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THE 
 
 ANATOMY 
 
 OF THE 
 
 HUmAM BODY. 
 
 BY J. CRUVEILHIER, 
 
 n07X8S0B OF ANATOMY TO THE FACULTY OF MEDICINE OF PARIS, PHYSICIAN TO THE HOSPITAL Of 
 8ALPETBIEBE, AND PRESIDENT OF THE ANATOMICAL SOCIETY OF PARIS. 
 
 THE FIRST AMERICAN, FROM THP USJ" .^ARIS EDITION. 
 
 Edited by 
 
 GRANVILLE SHARP PATTISON, M.D., 
 
 VK07ESSOR OF ANATOMY IN THE UNIVEItSITY OF NEW-YORK, MEMBER OF THE MEDIC0-CHIRUR0IC4I 
 
 SOCIETY OF LONDON, OF THE WARNF.RIAN SOCIETY OF NATURAL HISTORY OF EDINBURGH, OF 
 
 THE SOCIETE MEDICALS D'EMULATION, AND SOCIETE PHILOMATIQUE OF PARIS. 
 
 THIRD EDITION. 
 
 NEW-YORK: 
 
 HARPER & BROTHERS, PUBLISHERS 
 
 329 & 331 PEARL STREET, 
 FRANKLIN SQUARE. 
 
 1853. 
 1\ 
 
Entered, according to Act of Congress, in the year 1844, by 
 
 Harper & Brothers, 
 In the Clerk's Office of the Southern District of New-TC ork 
 
 » . 
 

 EDITOR'S PREFACE. 
 
 Numerous and excellent as the works on Anatomy are which have 
 lately been reprinted in this country, still they are, all of them, so de- 
 cidedly inferior to the " Svstem op Anatomy by Cruveilhier," that 
 the editor feels it unnecessary to offer any apology for having under- 
 taken its republication. Occupying, however, as he does the Chair of 
 Anatomy in the Metropolitan University of the United States, the pro- 
 fession may perhaps think that it would have been more becoming of 
 him to have published a System of Anatomy of his own, rather than to 
 have undertaken the humble office of editing the work of a European 
 anatomist. 
 
 The reasons which have influenced him in the course he has pur- 
 sued are the following : 
 
 The science of Anatomy, viewed abstractly, and without reference 
 to its connexion with Physiology, Pathology, and the Practice of Med- 
 icine and Surgery, is to the student just commencing a very dry and 
 uninteresting study. Yet in this way it is generally taught in the 
 schools, each system being demonstrated separately, without refer- 
 ence to the others, or to the Physiological and Pathological facts which 
 its demonstrations tend to illustrate. The course followed by the 
 editor, as a teacher of Anatomy, as his numerous students are aware, is 
 very difierent. His great object has always been to endeavour to give 
 interest to every lesson, by making it not a mere lecture on Anatomy, 
 but a discourse illustrating Physiological and Pathological science, and 
 elucidating the principles which should guide the practitioner in the 
 practice of his profession. 
 
 For the editor to have prepared a mere system of Anatomy would 
 have been, in fact, merely to have undertaken the work of a compiler ; 
 originality was out of the question, and no industry nor effort could 
 have enabled him to have produced, on this plan, a better work tha^ 
 the systems of Wilson, Quain, or the numerous other systematic trea- 
 tises on Anatomy which have already been published. The editor 
 having been a teacher of Anatomy for more than thirty years, from 
 his experience is fully aware of the vast importance to the successful 
 performance of his duties as an anatomical professor, of his being en- 
 abled to interest his pupils and to fix and enchain their attention, that he 
 is very unwilling to do anything which could have the effect of taking 
 from the intoi'(>Ht or diminishing the freshness of his lectures. To pub- 
 
 13430 
 
IV EDITOR 8 PREFACE. 
 
 lish a system of Anatomy on the same plan as that adopted in his lec- 
 tures, he would, of necessity, require to imbody in it the same Phys- 
 iological, Pathological, and practical views with which they are illus- 
 trated ; and to have done so> he cannot doubt but that the interest of 
 his lectures would have been diminished, and that he would in future 
 have found it much more difficult to fix the attention of his pupils. 
 This consideration has decided him never to publish, so long as he is 
 engaged in the duties of teaching, an original work on Anatomy. 
 
 The system of Anatomy of Cruveilhier has recommended itself to 
 the editor for publication : First, on account of its decided superiority 
 to any other work on Anatomy which has ever been published ; and, 
 secondly, from its being prepared, in some measure, in accordance 
 with the plan which he follows in his lectures, many of its details be- 
 ing illustrated by Physiological and Pathological references. 
 
 In republishing the work, the editor has so restricted himself in the 
 performance of liis task that he feels it can neither add to nor take 
 from his reputation. He has merely furnished to the members of the 
 profession in the United States The System of Anatomy op Cru- 
 veilhier. Several reasons have influenced him in being sparing in 
 the introduction of notes or additional matter. First. The work is in 
 itself so perfect as not to require them. Secondly. It is very volumi- 
 nous, and to have increased its size would have been to have diminish- 
 ed its value. Thirdly. The editor has ever thought that an inde- 
 pendent mind will shrink from mixing up and incorporating his 
 thoughts with those of another. If a man wishes to obtain reputation 
 as an author, let him publish an original work, and not attempt to gain 
 popularity by illustrating and enlarging the labours of another. 
 
 Since the English edition of Cruveilhier has been published in Lon- 
 don, the first and second volumes of a second edition of the work have 
 been published by the author in Paris. The editor has carefully com- 
 pared the second edition with the fi»st, so far as it has been published, 
 and has incorporated in the American edition whatever he thought 
 could increase its value. He has, however, only followed the second 
 edition when he thought that the changes introduced were improve- 
 ments. In many instances, with the view of keeping down the size o^ 
 the book, he has condensed into a few short paragraphs the substance 
 of several pages. In the department of Myology the author has in 
 his second edition made very numerous alterations from the first. As 
 these, in the opinion of the editor, have rather diminished than in- 
 creased the value of the work, he has only in a very few instances adopt- 
 ed them. The student, he feels satisfied, will find the description of the 
 muscles sufficiently minute. The subdivisions introduced, and the 
 minutiae which are added to their descriptions in the second edition. 
 
EDITOR :> l'Rt:rACF 
 
 would tend rather to embarrass than to piuiuure their improvement; 
 he has, therefore, very generally preferred to follow the first edition 
 in the description of the muscles. 
 
 In the original work there are no engravings ; this is a great desidera- 
 tum, which has been removed in the English edition by the introduc- 
 tion of numerous woodcuts, selected with care from the best anatomi- 
 cal engravings, and marked with letters of reference. This greatly 
 enhances the value of the work. The translation, which is an excel- 
 lent one, was made by Dr. Madden. 
 
 Systems of Anatomy generally offer little interest except to the 
 anatomical student. This cannot be said of the system of Anatomy of 
 Cruveilhier. It imbodies a fund of information, in connexion with 
 Physiology and Pathology, which will, in the opinion of the editor, pro- 
 cure for it a place in the library of every physician and surgeon who 
 feels any interest in his profession. If the members of the profession 
 only procure the book and peruse it, he cannot doubt but that the 
 cause of Anatomical science will be greatly promoted in the United 
 States ; and should this be the case, the editor will be amply repaid for 
 any trouble he may have had in undertaking the republication of Cru- 
 veilhier. 
 
 University of New-York, Sept. Ist, l^A^. 
 
k 
 
AUTHOR'S PREFACE. 
 
 The study of man offers three very different objects for contemplation ; viz., his or- 
 ganization, his vital functions, and his moral and intellectual faculties. 
 
 The organization or structure of man is the object of anatomy, a science which in- 
 vestigates every distinguishable material condition of the different parts that enter into 
 the construction of his frame. Anatomy is a science of observation, and is, in this re- 
 spect, susceptible of mathematical precision and physical certainty. 
 
 The vital functions of man are the objects of physiology, which reveals to us the ac- 
 tions of organs, with whose structure anatomy has previously made us acquainted. The 
 science of physiology inquires into the various motions that occur within the human 
 body, just as anatomy investigates the form of its component parts. All that we know, 
 in fact, concerning material objects, may be resolved into a knowledge of their motions 
 and their forms. 
 
 As a moral and intellectual being, man is the object of the science of psychology, 
 which contemplates him in the exercise of thought and volition, analyzes the operations 
 of his mind and will, and classifies them according to their supremacy. 
 
 A perfect acquaintance with man necessarily presupposes a combination of all that is 
 taught by these three sciences ; and it is because his anatomy, his physiology, and his 
 moral and intellectual endowments have not been studied by the same class of philoso- 
 phers, that in the sciences relating to himself so much yet remains to be desired. 
 
 Anatomy — the immediate object of this work — constitutes the foundation of medicine. 
 In order to discover the precise seat of a defect in some complicated machine, and the 
 means to be adopted for the reparation of its disordered mechanism, it is necessary to 
 be acquainted with the relative importance, and the particular action of all its constitu- 
 ent parts. " The human body," says Bacon, " may be compared, from its complex and 
 delicate organization, to a musical instrument of the most perfect construction, but ex- 
 ceedingly liable to derangement." And the whole science of medicine is therefore re- 
 duced to a knowledge of the means by which that harmonious instrument, the human 
 frame, may be so tuned and touched as to yield correct and pleasing sounds. 
 
 But since anatomy forms, as it were, the vestibule of medical science, it is of im- 
 portance that he who is entering upon its pursuit should fully understand the path he is 
 about to tread ; it is necessary, therefore, to assign, on the one hand, the rank which 
 medicine holds as a natural science, and, on the other, the position of anatomy among 
 the various sciences relating to medicine. 
 
 The term science, according to the admirable definition of the Roman orator, signifies 
 certain knowledge, deduced from certain principles — cognitio certa ex principiis certis ex- 
 orta. Sciences are divided into the metaphysical, the mathematical, and the natural ; but 
 since the two former are not connected with our present subject, we shall direct atten- 
 tion to the natural sciences only. 
 
 The object of the natural sciences, or of physics, taken in its widest signification, is a 
 knowledge of the materials of which the universe is composed, and of the laws by which 
 they are governed. They are subdivided into the physical, and the physiological or zoo- 
 logical. 
 
 The physical sciences take into consideration all the phenomena presented by inor- 
 ganic bodies; they comprise, 1. Astronomy, which studies the heavenly bodies as they 
 revolve in space, and estimates, by the aid of numbers, the laws by which their move- 
 ments are governed ; 2. Physics, properly so called, or the study of the properties of 
 matter in general ; in aid of which, experiments are performed in order to exhibit phe- 
 nomena in every possible light, and calculation is employed to render fruitful the results 
 of experiment ; 3. Geology, or that science which studies the surface of the globe, and 
 the successive strata which are met with in its interior ; which goes back far beyond all 
 historical traditions, brings to light, as it were, the very depths of the earth, and traces, 
 with a sure hand, the history of the globe, and the various revolutions it has undergone ; 
 4. Chemistry, which consists in the study of the reciprocal actions of bodies, when re- 
 duced to their atomic condition. 
 
 The zoological or physiological sciences embrace all the phenomena presented by living 
 bodies. The science of botany examines into the structure and functions of plants ; but 
 zoology, properly so called, investigates the organization and the life of animals. The 
 examination into structure or organization constitutes anatomy. Physiology embraces 
 the study of functions or of life. 
 
 The facts presented to us in the zoological are of a totally different character from 
 those comprised in the physical sciences, Inorganic bodies, in fact, are governed by 
 constant and immutable laws, acting in perfect harmony with each other ; but living 
 bodies are subject not only to physical, but also to vital laws, the latter of which are 
 constantly struggling against the former. This struggle constitutes life ; death is the 
 triumph of the physical over the vital laws. In consequence, however, of this continual 
 strife, derangements of structure and disordered functions very often occur ; and these 
 become more frequent and more complicated, in proportion as the organization is more 
 highly developed, and the animal more elevated in the scale of creation. 
 
 A knowledge of these derangements and of the proper means for restoring both or 
 
vui author's preface. 
 
 ganization and life to a healthy condition, constitutes the science of medicine ; and the 
 station which I have just assigned to this most important branch of zoological science 
 will prove, better than any arguments, that the study of the physiological or healthy 
 state of organization and of life should precede that of their pathological or diseased 
 conditions ; and that anatomy forms the first link in the chain of medical science. 
 
 Each science has its own methods of investigation, and its peculiar elements of cer- 
 tainty. Metaphysics and moral philosophy have a metaphysical and moral certainty. 
 The mathematical sciences set out from a small number of self-evident propositions or 
 axioms founded upon the nature of things, proceed gradually from the known to the un- 
 known, and trust to problems already demonstrated as to so many axioms, by means of 
 which, as steps, they again ascend towards new truths. The natural sciences, again, 
 are founded upon observation, and observation is merely the evidence of our senses ; 
 hence arises the necessity of exercising them, in order to increase their acuteness and 
 their activity. Facts, therefore, constitute the elements of the natural sciences ; and 
 then reasoning follows, founded upon those facts and upon analogy. It would be absurd 
 to study the natural sciences after the same method as metaphysics. 
 
 It may readily be understood, that as the purely physical sciences are based upon con- 
 stant phenomena, mathematics are directly applicable to them, and hence they are termed 
 physico-mathematical sciences; but in the zoological sciences, effects are continually 
 varying, according to their causes. Any attempts, therefore, to apply the art of numbers 
 to the elements of medicine, would be to imitate the philosopher, Condorcet, who enter- 
 tained the whimsical notion of subjecting moral probabilities to the test of mathematical 
 precision ; who was anxious to substitute a-\-b for either oral or written legal testimony ; 
 who admitted half proofs and fractional proofs, and then reduced them to equations, by 
 means of which he supposed he could arrive at arithmetical decisions, regarding the 
 lives, the fortunes, and the characters of his fellow-men. 
 
 It must, however, be reluctantly confessed, that we can acquire a knowledge only of 
 the surfaces of a body ; and that to say we are acquainted with its texture, is to state, 
 in other words, that we have a knowledge of the smallest surfaces comprised within its 
 general surface. Sight, touch, &c., the only means of investigation by which we can 
 appreciate the qualities of matter in general, can recognise nothing but surfaces, appear- 
 ances, and relative properties. Absolute properties they are unable to detect. With our 
 organization, we shall never know of what material objects essentially consist, but only 
 what they are in relation to ourselves. 
 
 This work being essentially of an elementary nature, and in some measure adapted 
 for the lecture-room, I have endeavoured to confine myself within narrow limits, and 
 strictly to avoid all considerations which are not inunediately connected with the anato- 
 my of organs. At the same time I have not forgotten that this work was intended for 
 the student of medicine, and not for the naturalist ; I have, therefore, been induced, in 
 the following pages, if not expressly to indicate, at least to direct attention to the more 
 immediate applications of anatomy to physiology, surgery, and medicine. 
 
 The objects which I have constantly had in view have been to exhibit the actual state 
 of the science of anatomy ; to present its numerous facts in their most natural order ; 
 to describe each fact clearly, precisely, and methodically ; to adopt such a method as 
 would form an easy guide to the student, and not involve him in confusion ; and, lastly, 
 to give to each detail its peculiar value, by invariably directing particular attention to 
 the more important points, instead of confounding them with matters of less consequence, 
 in an indigested and monotonous enumeration of facts. 
 
 The following is the order in which the principal divisions of the subject have been 
 treated. 
 
 The first division comprises Osteology, Arthrology or Syndesmology, and Odontology. 
 
 1. Osteology, which, notwithstanding the great number of works on the subject, seema 
 always to offer some new facts to those who study it with zeal, has been treated with 
 the attention it deserves, as forming the basis of anatomical knowledge. An account 
 of the development of the osseous system has appeared to me necessary for the comple- 
 tion of its history. I have therefore considered the following points in connexion with 
 the development of each bone : the number of ossific points ; the time of appearance of 
 the primitive and complementary ossific points ; the periods at which the several points 
 unite, and the changes occurring in the bone subsequently to its growth. By adopting 
 this method, the most complicated ossifications are reduced to a few propositions easily 
 retained in the memory. 
 
 The inconvenience arising from including in a description of the bones all the attach- 
 ments of the muscles, and nearly the whole anatomy of the part, is so totally at variance 
 with a methodical arrangement of facts, that it is unnecessary to offer an apology for the 
 changes made in this respect. Occasionally, however, I have mentioned those muscu- 
 lar attachments which might serve to characterize the osseous surfaces on which they 
 are situated. 
 
 2. Under the title of Syndesmology, or Arthrology, are united all the articulations of 
 the human body. Assummg as the only basis of classification the form of the articula- 
 ted surfaces, which is always in aocordanoc with the means of union and tlic movements 
 of tlie joint. I have bnen iu'liieofl tn mo lify thi- division.'^ nsuallv adopted. Tlic runilt'Li- 
 
AUTHOR S PREFACE. IX 
 
 throsis, or comyloid arliculaium, and the articulation by mutiial reception, form quite as 
 natural genera as the enarthrosis and the arthrodia. It will, perhaps, be found that the 
 characters of the different kinds of articulation, and in particular those of the anpxlar 
 ginglymus, which I have called the trochlear articulation, and those of the lateral gingly- 
 mus, or the trochoid articulation of the ancients, are more clearly defined than in other 
 anatomical works. 
 
 The mechanism, t. e., the movements of a joint, is so intimately connected with its 
 anatomy, that it was impossible to pass it over in silence ; on the other hand, it was 
 sometimes difficult to determine the limit which ought to distinguish an anatomical from 
 a physiological treatise. I have endeavoured to avoid both extremes, by confining my- 
 self strictly to the mechanism of each joint in particular, referring to works on physiol- 
 ogy for the principal movements of locomotion, and of animal statics, such as waUiing, 
 running, standing, &c. 
 
 3. Odontology, or the description of the teeth, concludes the first division. I have ta- 
 ken care to point out that this juxtaposition of the bones and the teeth was founded upon 
 their common indestructibility, and not upon the identity of their nature ; the bones be- 
 ing organs composed of living tissues, while the hard portion of the teeth, on the other 
 hand, is but the solidified product of secretion.* 
 
 The second division includes Myology, Aponeurology, and Splanchnology. 
 
 1. In treating of Myology, I have preferred the topographical to the physiological ar- 
 rangement of the muscles, for this reason only, that it admits of all of them being studied 
 upon the same subject. To unite, as far as was practicable, the undoubted advantages 
 possessed by both methods, I have given, at the conclusion of myology, a general sketch 
 of the muscles, arranged according to their physiological relations ; and by grouping 
 them, not after their order of super-imposition, but according to their several actions, I 
 have arranged them around the articulations to which they may belong, and have point- 
 ed out the extensors, the flexors, &c. 
 
 A muscle being known when its attachments are ascertained, I have thought it advi- 
 sable to commence the description of each by a brief announcement of its origin and in- 
 sertion, as a sort of definition or summary. The particular details concerning its mode 
 of insertion, whether it be aponeurotic or fleshy, and concerning the direction of its fibres, 
 complete the description of each muscle considered by itself ; the history of which is 
 concluded by an examination of its relations to neighbouring parts, and of its uses. The 
 individual or combined action of the muscles, for the production of simple movements, 
 follows so naturally after their description, and presupposes so correct and positive a 
 knowledge of their anatomy, that it can be treated of with propriety only in a work on 
 anatomy. The compound movements necessary for the consecutive or simultaneous 
 action of a great number of muscles come within the province of physiology. 
 
 2. The aponeuroses, those important appendages of the muscular system, are separ- 
 ately noticed, in connexion with the muscles to which they belong ; but I have also de- 
 scribed them together under the head of Aponeurology. This combination of analogous 
 parts possesses the twofold advantage of simplifying the science, by enabling one part 
 to elucidate the structure of another, and of permitting us to discover the general laws 
 according to which these structures are disposed. 
 
 3. With some modification, I have adopted that old division of anatomy, which treats 
 of the viscera and organs, and which is known by the name of Splanchnology. 
 
 The brain and the organs of the senses, which were included in this division in all 
 anatomical works preceding those of Soemmering and Bichat, have been removed from 
 it, and described with the other portions of the nervous system. The description of the 
 heart, in like manner, will be found with that of the other organs of circulation. In 
 short, the old classification of the viscera, according to their locality, that is, into those 
 of the head, the neck, the chest, &c., has been replaced by a more physiological arrange- 
 ment. Splanchnology will therefore comprehend a description of the organs of digestion 
 and their appendages, of the organs of respiration (among which is included the larynx, 
 or the organ of voice), and, lastly, the genito-urinary organs. 
 
 To the inquiry why I have departed from the usual custom of placing splanchnology 
 at the end of anatomy, I reply that, in order to study, with advantage, the vessels and 
 the nerves, it is necessary to have a previous acquaintance with the organs to which 
 they are distributed. 
 
 The importance of the parts described in this division, and the practical results which 
 flow from even the most superficial knowledge of their forms, connexions, and intimate 
 structure, are at once my reason and excuse for extending, to so great a length, this 
 portion of the work ; and, moreover, it is necessary to state, that there are many medi- 
 cal practitioners who learn anatomy only from elementary works. 
 
 The third and the last division treats of the organs of circulation, viz., the heart, arter- 
 ies, veins, and lymphatics ; and of the sensory apparatus, viz., the organs of the senses, 
 the brain, and the nerves. 
 
 1 . No part of anatomy, perhaps, has been better known than the arteries, since the 
 appearance of Haller's admirable works ; I could neither have followed a better guide 
 nor a more perfect model. 
 
 * See n.ilr. n. 1S3. 
 
 u 
 
X author's peeface. 
 
 2. The study of the vei?is has acquired an unexpected degree of importance, in conse- 
 quence of the works of various physicians on phlebitis ; and our knowledge of them has 
 been mucli extended by the researches of M. Dupuytren into the veins of the spine, and 
 the excellent plates of this order of vessels published by M. Breschet. 
 
 3. The study of the lymphatics has been almost abandoned since the very remarkable 
 publications of Mascagni : I have endeavoured to ascertain what credit was to be given 
 to the assertions of some modern writers concerning the frequent communication be- 
 tween the veins and the lyniphatics. 
 
 4. The work of Soemmering on the organs of the senses constitutes, perhaps, the high- 
 est title to fame possessed by that great anatomist ; and it might even be said that he 
 has left nothing for his successors to accomplish, did not the constant study of a science 
 of observation unceasingly proclaim this important truth, that it is in the power of no 
 man to declare, beyond this limit thou shalt not pass. 
 
 The brain and the nerves, to which so many able and laborious inquirers have lately 
 directed their attention, have been my favourite objects of investigation ; on account of 
 their importance, and perhaps, also, from the difficulties attending their study. Not sat- 
 isfied with simply tracing the nerves to the various organs in the body, I have studied 
 them in the interior of those organs, and have endeavoured to ascertain the precise 
 branches that are distributed to each particular part. 
 
 I may add, that, in order to facilitate the dissection of the nervous system, and, indeed, 
 of all the other parts of the body, I have presented, whenever it was necessary, a short 
 account of the best method of preparation. 
 
 With regard to the general spirit of this work, I have been anxious to render it clas- 
 sical ; and have avoided, most scrupulously, that species of induction and analogical rea- 
 soning, which, in a great measure, constitutes philosophical anatomy. To this kind of 
 anatomy I have never even introduced any allusions, except when its general ideas and 
 views (almost always ingenious, but usually bold and speculative) might elucidate our 
 own subjects. 
 
 All the descriptions have been made from actual dissections. It was only after hav- 
 ing completed from nature the account of each organ that I consulted writers, whose 
 imposing authority could then no longer confine my thoughts, but always excited me to 
 renewed investigations wherever any discrepancy existed. 
 
 Anatomy being, as already stated, the basis of medical science, we should greatly 
 misapprehend its nature did we not consider it the chief of the accessory sciences of 
 medicine. 
 
 Without it, the physiologist rears his structure upon sand ; for physiology is nothing 
 more than the interpretation of anatomy. It is anatomy that guides the eye and the 
 hand of the surgeon ; that inspires him with that ready confidence, which leads him to 
 search among structures, whose lesion would be dangerous or mortal, for some vessel 
 that must be tied, or for a tumour which must be extirpated. Nor is it less indispensa- 
 ble to the physician, to whom it reveals the seat of diseases, and the changes of form, 
 size, relation, and texture, which the affected organs have undergone. 
 
 Anatomy is, moreover, the science which, of all others, excites the greatest curiosity. 
 If the mineralogist and the botanist are so eager, the one to determine the nature of a 
 stone, the other to ascertain the characters of a flower ; if the love of their particular 
 science induces them to undertake the most dangerous voyages, in order to enrich it 
 with a new species, what ought to be our ardour in pursuing the study of man, that 
 masterpiece of creation, whose structure, possessed of both delicacy and strength, ex- 
 hibits so much harmony as a whole, and displays so much perfection in its parts ! 
 
 And while contemplating this marvellous organization, in which all has been provided 
 and prearranged with such intelligence and wisdom, that no single fibre can acquire the 
 slightest addition, or undergo the least diminution of power, without the equilibrium be- 
 ing destroyed and disorder being induced — what anatomist is there who would not feel 
 tempted to exclaim, with Galen, that a work on anatomy is the most beautiful hymn 
 which man can chant in honour of his Creator !* 
 
 May this work inspire among students an ever-increasing ardour for the study of the 
 organization of man, which, even if it were not the most eminently useful, would still 
 be the most interesting, and the most beautiful of all the sciences. And what more 
 powerful motive for emulation can present itself to a generous mind, than the idea, 
 "that every acquisition of knowledge is a conquest achieved for the relief of suffering 
 humanity !" Let it never be forgotten that, without anatomy, there is no physiology, no 
 surgery, no medicine ; that, in a word, all the medical sciences are grafted upon anato- 
 my as upon a stock ; and that the deeper its roots descend, the more vigorous will be 
 its branches, and the more abundantly laden with flowers and with fruit. 
 
 I must here express my acknowledgments to M. Chassaignac, the anatomical assist- 
 ant to the Faculty, who has distinguished himself in several concours, and who has as- 
 sisted me with the greatest zeal in the execution of this work. 
 
 * " Sacrum sermonem quem ego Conditoris nostri verum hyranum compono, existimoque in hoc veram esse 
 pietatem, non si tauroruni hecatombas ei sacrificaverim. et casias, aliaque sexcenta odoramenta ac unguenta 
 suffumigaverim, sod si noverini ipse primus, deiude ct aliis exposuerim quffinam sit ipsius sapicntia.quce virtus. 
 ciUii! bomtas."— (Galen, De usu part., lib iii.) 
 
CONTENTS. 
 
 INTRODUCTION. 
 Object and Division of Anatomy. — General View of the Human Frame. — Apparatus of Sensation— of lo- 
 comotion— of Nutrition— of Reproduction. — General Plan of tlie Worli Page 1 
 
 APPARATUS OF LOCOMOTION. 
 OSTEOLOGY. 
 Of the Bones in Oeneral. 
 The Bones— Importance of their Study.— General View of the Skeleton. — Number of the Bones.— Method 
 of Description.— Nomenclature.— Situation in general.— Direction.— Size, Weight, and Density of Bones. 
 — Figure. — Distinction into long, broad, and flat Bones. — Regions of Bones. — Eminences and Cavities. — 
 Internal Conformation. — Texture. — Development, or Osteogeny.— Nutrition 5 
 
 The Vertebral Column. 
 
 General Characters of the Vertebrse. — Characters peculiar to the Vertebrse of each Region. — Characters 
 
 proper to certain Vertebrae. — Vertebree of the Sacro-coccygeal Region. — The Vertebral Column in general. 
 
 — Development 18 
 
 The Scull. 
 
 Composed of the Cranium and Face. — Cranial Bones — Occipital — Frontal — Sphenoid — CEthmoid — Parietal 
 
 — Temporal. — The Cranium in general. — Development. — Bones of the Face— Superior Maxillary. — Palate. 
 
 — Malar. — Nasal. — Lachrymal — Inferior turbinated. — Vomer— Inferior Maxillary. — The Face in general. 
 
 — Cavities. — Development 33 
 
 The Thorax, or Chest. 
 
 The Sternum.— Ribs.— Costal Cartilages.— The Thorax in general.— Development 64 
 
 The Superior, or Thoracic Extremities. 
 The Shoulder.— Clavicle.— Scapula.— The Shoulder in general.— Development.— Humerus.— Ulna.— Radius. 
 —The Hand— The Carpus and Carpal Bones.— The Metacarpus and Metacarpal Bones.— The Fingers.— 
 General Development of the Superior Extremities 73 
 
 The Inferior, or .Abdominal Extremities. 
 
 The Haunch.— Os Coxse.— The Pelvis.— Development.— Femur.— Patella.— Tibia.— Fibula.— The Foot.— 
 The Tarsus and Tarsal Bones. — The Metatarsus and Metatarsal Bones.— The Toes. — Development of the 
 Lower ExUemities. — Comparison of the Upper and Lower Extremities. — Os Hyoides . . . .87 
 
 The .Articulations, or Arthrology. 
 
 General Observations. — Articular Cartilages. — Ligaments. — Synovial Membranes. — Classification of the 
 
 Joints,— Diarthroses. — Synarthroses. — Amphiarthroses, or Symphyses Ill 
 
 .Articulations of the Vertebral Column. 
 Articulations of the Vertebra with each other. — Those peculiar to certain Vertebra;. — Sacro-vertebral. Sa- 
 cro-coccygeal, and Coccygeal Articulations. — Articulations of the Cranium— of the Face — of the Tho- 
 rax 115 
 
 Articulations of the Superior or Thoracic Extremities. 
 Articulations of the Shoulder. — Scapulo-humeral. — Humero-cubital. — Radio-cubital. — Radio-carpal. — Of 
 the Carpus and Metacarpus. — Of the Fingers 135 
 
 Articulations of the Inferior or Abdominal Extremities. 
 
 Articulations of the Pelvis.— Coxo-femoral. — Knee-joint.— Peroneo-tibial. — Ankle-joint.— Of the Tarsus.— 
 
 Tarso-metatarsal. — Of the Toes 154 
 
 ODONTOLOGY. 
 Circumstances in which the Teeth differ from Bones. — Number. — Position.— External Conformation.— Gen- 
 eral Characters. — Classification— Incisor — Canine— Molar.— Structure. — Development . . . .177 
 
 MYOLOGY. 
 The Muscles in general. — Nomenclature. — Number. — Volume and Substance. — Figure. — Dissection. — Rela- 
 tions. — Attachments. — Structure. — Uses. — Preparation. — Order of Description . . . .190 
 
 Muscles of the Posterior Region of the TVunk. 
 The Trapezius.— Latissimus Dorsi and Teres Major.— Rhomboideus. — Levator Anguli Scapula.- Serrati , 
 
 Postici. — Splenius. — Posterior Spinal Muscles. — Complexus. — Inter-spinales Colli. — Recti Capitis Postici, | 
 
 Major et Minor. — Obliqui Capitis, Major et Minor. — General View and Action of the Posterior Spinal 
 Muscles 198 
 
 Muscles of the Anterior Abdominal Region. 
 The Obliquus Externus Abdominis. — Obliquuslntemus and Cremaster. — Transversalis Abdominis. — Rectus 
 Abdominis.— Pyramidalis 208 
 
 Diaphragmatic Region 212 
 
 Lumbar Region. 
 
 The Psoas and lUacus. — Psoas Parvus. — Ciuadratus Lumborum . . 214 ^ 
 
 Lateral Vertebral Region. 
 Tholnter-transversales and Rectus Capitis Lateralis.— Scaleni .217 
 
# 
 
 XU CONTENTS. 
 
 Deep Anterior Cervical, or Prevertebral, Region. 
 The Recti Capitis Antici, Major et Minor.— Longus Colli.— Action of these Muscles . . . Page 318 
 
 Thoracic Region. 
 The Pectoralis Major.— Pectoralis Minor.— Sub-clavius.—Serratus Magnus. — Intercostalei.— Supra-costales. 
 — Infra-costales. — Triangularis Sterni 220 
 
 Superficial Anterior Cervical Region. 
 
 The Platysma Myoides. — Sterno-cleido-itiastoideus 234 
 
 Muscles of the Infra-hyoid Region. 
 The Sterno-hyoideus. — Scapulo- or Omo-hyoideus. — Sterno-thyroideus. — Thyrohyoideus . . . 5^ 
 
 Muscles of the Supra-hyoid Region. 
 
 The Digastricus — Stylo-hyoideus. — Mylo-hyoideus. — Genio-hyoideus.— Their Action .... 228 
 
 Muscles of the Cranial Region. 
 
 Occipito-frontalis. — Auricular Muscles 230 
 
 Muscles of the Palpebral Region. 
 Orbicularis Palpebrarum. — Superciliaris. — Levator Palpebrae Superioris .... . . 231 
 
 JVasal Region. 
 The Pjramidalis Nasi.— Levator Labii Superioris Alaeque Nasi.— TransTersalis, or Triangularis Nasi^— De 
 pressor Alie Nasi. — N^so-labialis 233 
 
 Muscles of the Labial Region. 
 The Orbicularis Oris. — Buccinator. — Levator Labii Superioris. — Caninus. — Zygontatici, Major et Minor. 
 Triangularis. — Quadratus Menti. — Levator Labii Superioris. — Movements of the Lips and those of the 
 Face 234 
 
 Muscles of the Temporo-maxillary Region. 
 
 The Masseter and Temporalis 339 
 
 The Pterygo-maxillary Region. 
 
 The Pterygoideiu Intemus. — The Pterygoideus Kxternus 240 
 
 Muscles of the Shoulder. 
 The Deltoideus. — Supraspinatus. — Infra-spinatug and Teres Minor. — Sub-scapularis .... 341 
 
 Muscles of the Arm. 
 
 The Biceps. — Brachialis Anticus. — Coraco-brachialis. — ^Triceps Extensor Cubiti 244 
 
 Muscles of the Forearm 349 
 
 Muscles of the Hand. 
 The Abductor Brevis Pollicis. — Opponens Pollicis. — Flexor Brevis Pollicis. — Adductor PoIIicis. — Palmaris 
 Brevis. — Abductor Digit! Minimi. — Flexor Brevis Digiti Minimi. — Opponens Digiti Minimi. — ^The Interos- 
 seous Muscles, Dorsal and Palmar 260 
 
 Muscles of the Pelvis. 
 
 The GIutsBi Maximus, Medius, et Minimus. — Pyriformis. — Obturator Intemus. — Gemelli, Superior et Inferior. 
 
 ^^iuadratus Femoris. — Obturator Extern us. — Action of these Muscles 364 
 
 Muscles of the Thigh. 
 The Biceps Cruris. — Semi-tendinosus. — Semi-membranosus. — Tensor Vagina Femoris. — Sartorius. — Triceps 
 Extensor Cruris. — Gracilis. — Adductor Muscles of the Thigh 369 
 
 Muscles of the Leg. 
 The Tibialis Anticus. — The Extensor Communis Digitorum. — Extensor Proprius Pollicis. — Peronei Longus 
 et Brevis. — Gastrocnemius, Plantaris and Solaris. — Popliteus. — Tibialis Posticus. — Flexor Longus Pol- 
 licis 377 
 
 Muscles of the Fbot. 
 The Extensor Brevis Digitorum. — Abductor Pollicis Pedis. — Flexor Brevis Pollicis Pedis. — Adductor Pollicis 
 Pedis. — Transveisus Pollicis Pedis. — Abductor Digiti Minimi.— Flexor Brevis Digiti Minimi. — Flexor Bre- 
 vis Digitorum. — Flexor Accessorius. — Lumbricales. — Interossei 386 
 
 APONEUROLOGY. 
 
 Geaeral Observations on the Aponeuroses. — Structure. — Uses 294 
 
 Particular Aponeuroses. 
 Superficial Fascia. — Aponeuroses of the Cranium — of the Face — of the Neck — of the Thorax — of the Abdo- 
 men— of the Pelvis — of the Thigh, Leg, and Foot — of the Shoulder, Arm, Forearm, and Hand . . 397 
 
 SPLANCHNOLOGY. 
 
 General Observations on the Viscera.— External Conformation.- tructure.— Development.— Functions.— 
 Dissection 330 
 
 Tbk Qsgans of Digestion and theik Aitendages. 
 
 Alimentary or Digestive Canal. 
 General Observations. — Division. — Mouth and its Appendages. — Lips.— Cheeks. — Hard and soft Palate. — 
 Tonsils. — Tongue. — Salivary Glands. — Buccal Mucous Membrane. — Pharynx. — CEsophagus. — Stomach. — 
 Small Intestine. — Large Intestine. — Muscles of the Perineum. — Development of the Intestinal Canal . 333 
 
 Appendages of the Alimentary Canal. 
 Tlie Liver and its Excretory Apparatus.— The Pancreas. — ^The Spleen 384 
 
 The Organs of Respiration 
 General Observations.— The Lungs and Pleura;.— The Trachea and Bronchi.— Development of the Lungs. 
 —The Larynx— its Structure, Development, and Functions.— The Thyroid Gland .... 409 
 
CONTENTS. XUl 
 
 The Genito-Urinaey Organs. 
 
 Tlie Urinary Organs. 
 DiTiskw.— The Kidneys and Ureters.— The Bladder.— The Supra-renal Capsnles . . . Page 435 
 
 The Generative Organs. 
 The Oenerative Organs of the Male. 
 The Testicles and their Coverings.— The Epididymis, the Vasa Deferentia, and Vealcalsi Seminallte.— The 
 Penis.— The Urethra.— The Prostate and Cowper's Glands 446 
 
 The Generative Organs of the Female. 
 The Ovaries.- The FalloiMan Tubes.— The Uterus.— The Vagina.— The Urethra.— The Vulva . . 461 
 
 The Mammte. 
 Number.— Situation. — Size.— Form. — Structure.— Development 473 
 
 The Peritoneum. 
 The Sub-ombiUcal Portion. — The Supra-umbilical Portion.— General Description and Structure . . 479 
 
 ANGEIOLOGY. 
 
 Definition and Objects of Angeiology 479 
 
 The Heart. 
 General Description. — External and Internal Conformation. — Structure. — Development.— Functions. — The 
 Pericardium . 479 
 
 The Arteries. 
 Definition. — Nomenclature. — Origin. — Varieties. — Course. — Anastomoses. — Form and Relations. — Termina- 
 tion. — Structure. — Preparation 496 
 
 Description of the Arteries. 
 
 The Pulmonary Artery. 
 
 Preparation. — Description. — Relations. — Size. — Development 499 
 
 The Aorta. 
 Preparation.-Definition.— Situation. — Direction.— Size. — Division into the Arch of the Aorta, the Thoracic 
 
 Aorta, and the Abdominal Aorta 501 
 
 Collateral Branches of the Aorta. 
 Ehiumeration and Classification. — Arteries arising from the Aorta at its Origin, viz., the Coronary or Car- 
 diac.^Arteries arising from the Thoracic Aorta, viz., the Bronchial, the (Esophageal, the Intercostal.— 
 Arteries arising from the Abdominal Aorta, viz., the Lumbar, the Inferior Phrenic, the CcBliac Axis, in- 
 cluding the Coronary of the Stomach, the Hepatic, and the Splenic, the Superior Mesenteric, the Inferior 
 Mesenteric, the Spermatic, the Renal, and the Supra-renal or Capsular . . . . . .503 
 
 Arteries arising from the Arch of the Aorta. 
 Enumeration and Varieties. — The Common Carotids. — ^The External Carotid — the Superior Thyroid — the 
 Facial — the Lingual — the Occipital — the Posterior Auricular — the Parotid — the ascending Pharyngeal — 
 the Temporal — the Internal Maxillary. — ^The Internal Carotid— the Ophthalmic — the Cerebral Branches 
 of the Internal Carotid. — Summary of the Distribution of the Common Carotids. — Artery of the Upper 
 Extremity.— The Brachio-cephalic. — The Right and Left Sub-clavians— the Vertebral and its Cerebral 
 Branches, with Remarks on the Arteries of the Brain, Cerebellum, and Medulla — the Inferior Thyroid — 
 the Supra-scapular — the Posterior Scapular — the Internal Mammary — the deep Cervical — the Superior 
 Litercostal. — ^The Axillary — the Acromio-thoracic — the Long Thoracic — the Sub-scapular — the Posterior 
 Circumflex— the Anterior Circumflex. — ^The Brachial and its Collateral Branches. — The Radial, its Col- 
 lateral Branches, and the deep Palmar Arch. — The Ulnar, its Collateral Branches, and the Superficial 
 Palmar Arch. — General Remarks on the Arteries of the Upper Extremity 513 
 
 Arteries arising from the Termination of the Aorta. 
 Enumeration. — The Middle Sacral.— The Common Iliacs. — The Internal Iliac, or Hypogastric — ^the Umbil- 
 ical — the Vesical — the middle Haemorrhoidal — the Uterine — the Vaginal — the Obturator — the Ilio-lurabar 
 —the Lateral Sacral — the Glutsal — the Sciatic — the Internal Pudic. — Summary of the Distribution of 
 the Internal Iliac. — Artery of the Lower Extremity. — The External Iliac — the Epigastric— the Circumflex 
 Iliac. — The Femoral — the Superficial Epigastric — the External Pudic — the Muscular — the deep Femoral, 
 its Circumflex and Perforating Branches. — The Popliteal, and its Collateral Branches. — The Anterior 
 Tibial and the Dorsal Artery of the Foot. — The Tibio-peronenl — Peroneal — Posterior Tibial, and the In- 
 ternal and External Plantar. — Comparison between the Arteries of the Upper and Lower Extremities . 552 
 
 The Veins. 
 Definition.— The Venous System. — Origin of the Veins.— Course. — Anastomoses and Plexuses. — Varieties. 
 — Termiaation. — Valves. — Structure. — Preparation. — Method of Description 573 
 
 Description op the Veins. 
 
 The Pulmonary Veins 
 
 Preparation.— Description.— Relations.— Size.— Peculiarities 577 
 
 The Veins of the Heart. 
 The Great Coronaiy or Cardiac Vein.— The Small Cardiac Veins 577 
 
 The Superior, or Descending Vena Cava and its Branches, 
 The Superior Vena Cava. — The Brachio-cephalic Veins — the Inferior Thyroid — the Internal Mammary — 
 the Superior Phrenic, the Thymic, Pericardiac, and Mediastinal— the Vertebral. — ^The Jugular Veins, viz., 
 the External — the Anterior — and the Internal. — The Encephalic Veins, and the Sinuses of the Diuu 
 Mater, viz., the Lateral — the Superior Longitudinal — the Straight — the Superior and Inferior Petrosal — 
 the Cavernous — the Coronary — and the Anterior and Posterior Occipital Sinuses — the Conflux of the 
 Sinuses.— The Branches of Origin of the Jugular Veins— the Facial— tlie Temporo-maxiilarv- the Pos- 
 
k 
 
 XIT CONTENTS. 
 
 terior Auricular— the Occipital— the Lingual— the Pharyngeal— the Superior and Midcile ThsToid— the 
 Veins of the Dipioe. — Summary of the Distribution of the Veins of the Head. — The deep Veins of the 
 Upper Extremity — the Palmar, Radial, Ulnar, Brachial, and Axillary — the Sub-clavian. — The Superficial 
 Veins of the Upper Extremity — in the Hand — in the Forearm — at the Elbow— €uid in the Arm. — General 
 Remarks on these Superficial Veins Page 578 
 
 The Inferior, or Ascending Vena Cava and its Branches. 
 The Inferior Vena Cava — the Lumbar or Vertebro-lumbar Veins — the Renal — the Middle Supra-renal — the 
 Spermatic and Ovarian — the Inferior Phrenic. — The Portal System of Veins — the Branches of Origin of 
 tlie Vena Porta— the Vena Portae — the Hepatic Veins. — The Common liiacs — the Internal Iliac — the 
 Hemorrhoidal Veins and Plexuses — the Pelvic Veins and Plexuses in the Male and in the Female. — ^The 
 deep Veins of the Lower Extremity — the Plantar, Posterior Tibial, Peroneal, Dorsal, Anterior Tibial, and 
 Popliteal — the Femoral — the External Iliac. — The Superficial Veins of the Lower Extremity — the Inter- 
 nal Saphenous — the External Saphenous 596 
 
 The Veins of the Spine. 
 General Remarks. — The Superficial Veins of the Spine. — The Anterior Superficial Spinal Veins, viz., the 
 Greater Azygos — the Lesser Azygos — the Left Superior Vertebro-costals — the Right Vertebro-costals — 
 the Vertebro-lumbar — the Ilio-lurabar, and Middle and Lateral Sacral — the Anterior Superficial Spinal 
 Veins in the Neck. — The Posterior Superficial Spinal Veins. — The deep Spinal or Intra-spinal Veins — 
 the Anterior Longitudinal, and the Transverse Veins or Plexuses, and the Veins of the Vertebrte — the 
 Posterior and the Posterior and Lateral Transverse Veins or Plexuses — the Medullary Veins. — General 
 Remarks on the Veins of the Spine 605 
 
 The Lymphatic System. 
 Definition, History, and general View of the Lymphatic System. — Origin. — Course. — Termination and 
 Structure of the Lymphatic Vessels. — The Lymphatic Glands. — Preparation of the Lymphatic Vessels 
 and Glands 611 
 
 Description of the Lymphatic System. 
 
 The Thoracic Duct — the Right Thoracic Duct. — The Lymphatic System of the Lower Extremity — of t e 
 Pelvic and Lumbar Regions — of the Liver — of the Stomach, Spleen, and Pancreas— of the Intestines — of 
 the Thorax — of the Head — of the Cervical Regions — of the Upper Extremity and Upper Part of the 
 Trunk 620 
 
 NEUROLOGY. 
 The Organs of the Senses. 
 The Skin — its External Characters, Structure, and Appendages. — The Tongue considered as the Orgaa of 
 Taste. — The Organ of Smell — the Nose— the Pituitary Membrane. — The Organ of Sight — the Eyebrows 
 — the Eyelids — the Muscles of the Orbit — the Lachrymal Apparatus — the Globe of the Eye, its Mem- 
 branes and Humours — the Vessels and Nerves of the Eye. — The Organ of Hearing — the External Ear — 
 the Middle Ear or Tympanum — the Internal Ear or Labyrinth — the Nerves and Vessels of the Ear . 62fl 
 
 The Cerebro-spinal Axis. 
 
 General Observations 681 
 
 The Membranes of the Cerebro-spinal Axis. 
 General Remarks. — The Dura Mater — the Cranial Portion, its Structure and Uses— the Spinal Portion. — 
 The Arachnoid — its Cranial Portion — its Spinal Portion — the Sub-arachnoid Fluid — their Uses. — The Pia 
 Mater — its External Cerebral Portion 682 
 
 The Spinal Cord, and the Medulla Oblongata. 
 General View of the Cord — its Limits and Situation — the Ligamentum Denticulatum. — Size of the Spinal 
 Cord — Form, Directions, and Relations — the Cord in its Proper Membrane — the Proper Membrane, or 
 Neurilemma of the Cord — the Cord deprived of its Proper Membrane. — Internal Structure of the Cord — 
 Sections — Examination by means of Water, and when hardened in Alcohol — the Cavities or Ventricles 
 of the Cord. — ^The Medulla Oblongata — Situation — External Conformation — Anterior Surface, the Ante- 
 rior Pyramids and the Olivary Bodies — the Posterior Surface — the Lateral Surfaces — the Internal Struc- 
 ture — Sections — Examination by Dissection, and under Water. — Development of the Spinal Cord.— De- 
 velopment of the Medulla Oblongata. — Comparative Anatomy of the Spinal Cord. — Comparative Anatomy 
 of the Medulla Oblongata 693 
 
 The Isthmus of the Encephalon. 
 
 General Description and Division. — The Pons Varolii and Middle Peduncles of the Cerebellum — the Pedun- 
 cles of the Cerebrum — the Superior Peduncles of the Cerebellum and the Valve of Vieussens — the Cor- 
 pora Quadrigemina. — Internal Structure of the Isthmus, viz., of its Inferior, Middle, and Superior Strata. 
 — Sections. — Development. — Comparative Anatomy 710 
 
 The Cerebellum. 
 
 General Description. — External Characters and Conformation — Furrows, Lobules, Lamins, and Lamellte. 
 — Internal Conformation — the Fourth Ventricle, its Fibrous Layers, its Inferior Orifice, and its Choroid 
 Plexus. — Sections of the Cerebellum, Vertical and Horizontal. — Examination by Means of Water, and of 
 the hardened Cerebellum. — General Viev% nf the Organ. — Development. — Comparative Anatomy . 715 
 
 The Cerebrum, or Brain Proper. 
 
 Definition — Situation — Size and Weight — General Form. — The Superior or Convex Surtice. — 1 ne Inferior 
 Surface or Base — its Median Region, containing the Inter-peduncular Space, the Corpora Albicantia, the 
 Optic Tracts and Commissure, the Tuber Cinereum, Infundibuluni, and Pituitary Body, the Anterior Part 
 of the Floor of the Third Ventricle, the reflected Part of the Corpus Callosum, the Anterior Part of the 
 Longitudinal Fissure, the Posterior Part of the Longitudinal Fissure, the Posterior Extremity of the Corpus 
 Callosum and Median Portion of the Transverse Fissiu-e, and the Transverse Fissure. — The Lateral Re- 
 gions, including the Fissiu-e of Sylvius and the Lobes of the Brain. — The Convolutions and Anfractuosi- 
 ties of the Brain, upon its Inner Surface, its Base, and its Convex Surface — Uses of the Convolutions and 
 Anfractuosities. — The Internal Structure of the Brain — Examination by Sections — Horizontal Sections 
 showing the Corpus Callosum, the Septum Luciduni, the Fornix and Corpus Fimbriatum, the Velum In- 
 terpositum, the Middle or Third Ventricle, the Aqueduct of Sylvius, the Pineal Gland, the Lateral Ven- 
 tricle?, their Superior and Inferior Portions, the Choroid Plexus, and the Lining Membrane and the Fluid 
 of the Ventriclus — Mrdlan Vertical Section — Transverse Vertical Sections — Section of Willis. — General 
 
CONTENTS. XV 
 
 Remirks on this Method of examining the Brain.— Methods of Varolius, Vienssens, and Gall.— Gall and 
 Spurzheim's Views on the Structure of the Brain. — General Idea of the Brain.— Development. — Compar- 
 ative Anatomy ... Page 725 
 
 The Nerves, ob the Peripheral Portion of the Nervous System. 
 General Remarks. — History and Classification. — Origin, or Central Extremity. — Different Kinds. — Course, 
 Plexuses, and Anastomoses. — Direction, Relations, and Mode of Division. — Termination. — Nervous Gan- 
 glia, and the great Sympathetic System.— Conne.\ions of the Ganglia with each other, and with the Spi- 
 nal Nerves.— Structure of Nerves.— Structure of Ganglia.— Preparation of Nerves . . . .759 
 
 Description of the Nerves. 
 
 General Remarks.— Division into Spinal, Cranial, and Sympathetic Nerves 769 
 
 TVke Spinal JVerves. 
 Enumeration and Classification. — ^The Central Extremities, or Origins of the Spinal Nerves — Apparent Ori- 
 gins — Deep or real Origins. — The Posterior Branches of the Spinal Nerves — Common Characters — the 
 Posterior Branches of the Cervical Nerves, their Common and Proper Characters — the Posterior Branches 
 of the Dorsal, Lumbar, and Sacral Nerves. — The Anterior Branches of the Spinal Nerves — their General 
 Arrangement 770 
 
 The interior Branches of the Cervical JVerves. 
 Dissection. — Anterior Branch of the First, Second, Third, and Fourth Cervical Nerves. — The Cervical 
 Plexus— its Anterior Branch, the Superficial Cervical— its Ascending Branches, the great Auricular and 
 the External or Lesser Occipital— its Superficial Descending Branches, the Supra-clavicular— its deep De 
 scending Branches, the Nerve to the Descendens Noni and the Phrenic — its deep Posterior Branches. — 
 The Anterior Branches of the Fifth, Sixth, Seventh, and Eighth Cervical, and First Dorsal Nerves. — The 
 Brachial Plexus — its Collateral Branches above the Clavicle — its Muscular Branches, Posterior Thoracic, 
 Supra-scapular — opposite to the Clavicle the Thoracic, below the Clavicle the Circumflex — its Terminal 
 Branches, the Internal Cutaneous and its Accessory, the Musculo-cutaneous, the Median, the Ulnar, the 
 Musculo-spiral or Radial. — Summary of the Distribution of the Branches of the Brachial Plexus . 776 
 
 The interior Branches of the Dorsal JVerves, or the Intercostal JVerves. 
 
 Dissection. — Enumeration. — Common Characters. — Characters proper to each 794 
 
 The interior Branches of the Lumbar JVerves. 
 
 Enumeration.— The Lumbar Plexus.— Collateral Branches, Abdominal and Inguinal.— Terminal Branches 
 — the Obturator Nerve— the Crural Nerve and its Branches, viz., the Musculo-cutaneous— the Accessory 
 of the Internal Saphenous— the Branch to the Sheath of the Vessels— the Muscular Branches— the Inter- 
 nal Saphenous 796 
 
 The Anterior Branches of the Sacral M'erves. 
 
 Dissection. — Enumeration. — The Sacral Plexus. — Collateral Branches, viz., the Visceral Nerves — the Mus- 
 cular Nerves — the Inferior Hemorrhoidal — the Internal Pudic and its Branches — the Superior Gluteal 
 Nerve— the Inferior Gluteal, or Lesser Sciatic Nerve — the Nerves for the Pyramidalis, (iuadratus Fe- 
 moris, and Gemelli. — Terminal Branch of the Sacral Plexus, or the great Sciatic Nerve. — The External 
 Popliteal and its Branches — the Peroneal, Saphenous, Cutaneous, and Muscular Branches — the Musculo- 
 cutaneous — the Anterior Tibial. — The Internal Popliteal and its Branches — the Tibial or External Saphe- 
 nous — Muscular and Articular Branches — the Internal Plantar — the External Plantar. — Summary of the 
 Nerves of the Lower Extremity. — Comparison of the Nerves of the Upper with those of the Lower Ex- 
 tremity 804 
 
 T%e Cranial JVerves. 
 
 Definition and Classification. — ^The Central Extremities of the Cranial Nerves, viz., of the Olfactory— of 
 
 the Optic — of the Common Motor Oculi — of the Pathetic — of the Trigeminal — of the External Motor Oculi 
 
 — of the Portio Dura and Portio Mollis of the Seventh — of the Glosso-pharyngeal, Pneumogastric, and 
 
 Spinal Accessory Divisions of the Eighth — and of the Ninth Nerves 816 
 
 Distribution of the Cranial JVerves. 
 The First Pair, or Olfactory Nerves. — ^The Second, or Optic Nerves. — The Third, or Common Mdlor Nerves. 
 — The Fourth, or Pathetic Nerves. — The Fifth, or Trigeminal Nerves — the Ophthalmic Division of the 
 Fifth, and its Lachrymal, Frontal, and Nasal Branches — the Ophthalmic Ganglion — the Superior Maxil- 
 lary Division of the Fifth, and its Orbital Branch — the Spheno-palatine Ganglion, and its Palatine, Spheno- 
 palatine, and Vidian Branches — the Posterior and Anterior Dental, and the Terminal Branches of the Su- 
 perior Maxillary Nerve — the Inferior Maxillary Division of the Fifth — its Collateral Branches, viz., the 
 deep Temporal, the Masseteric, Buccal, and Internal Pterygoid, and Auriculo-temporal — its Terminal 
 Branches, viz., the Lingual and Inferior Dental — the Otic Ganglion. — The Sixth Pair, or External Motor 
 Nerves. — The Seventh Pair — the Portio Dura, or the Facial Nerve — its Collateral Branches — its Terminal 
 Branches, viz., the Temporo-facial and Cervico-facial — the Portio Mollis, or Auditory Nerve. — The Eighth 
 Pair — its First Portion, or the Glosso-pharyngeal' Nerve — its Second Portion, or the Pneumogastric Nerve, 
 divided into a Cranial, Cervical, Thoracic, and Abdominal Part— its Third Portion, or the Spinal Acces- 
 sory Nerve.— The Ninth Pair, or the Hypoglossal Nerves.— General View of the Cranial Nerves . 824 
 
 The Sympathetic System of JVerves. 
 €eneral Remarks.— The Cervical Portion of the Sympathetic. — The Superior Cervical Ganglion — its Supe- 
 rior Branch, Carotid Plexus, and Cavernous Plexus — its Anterior, External, Inferior, and Internal Branch- 
 es.— The Middle Cervical Ganglion. — The Inferior Cervical Ganglion. — The Vertebral Plexus. — The 
 Cardiac Nerves ; Right, Superior, Middle, and Inferior ; Left.— The Cardiac Ganglion and Plexuses.— The 
 Thoracic Portion of the Sympathetic- The External and Internal Branches.— The Splanchnic Nerves, 
 Great and Small.— The Visceral Ganglia and Plexuses in the Abdomen, viz., the Solar Plexus and Semi- 
 lunar Ganglia.— The Diaphragmatic and Supra-renal, the Coeliac, the Superior Mesenteric, the Inferior 
 Mesenteric, and the Renal, Spermatic, and Ovarian Plexuses.— The Lumbar Portion of the Sympathetic. 
 —The Communicating, External, and Internal Branches.— The Lumbar Splanchnic Nerves and Visceral 
 Plexuses in the Pelvis. — The Sacral Portion of the Sympathetic. — General View of the Sympathetic 
 System 854 
 
DESCRIPTIVE ANATOMY. 
 
 INTRODUCTION. 
 
 Object and Division of Anatomy. — General View of the Human Frame. — Apparatus of Sen- 
 sation — of Locomotion — of Nutrition — of Reproduction. — General Plan of the Work. 
 
 Considered in its most extended signification, Anatomy* is the science which has for 
 its object the structure of Uving beings. 
 
 Living beings are divided into two great classes, vegetables and animals ; there is, 
 therefore, a vegetable anatomy and an animal anatomy. When anatomy embraces, in one 
 general view, the whole series of animals, comparing the same organs as they exist in 
 ^he different species, it receives the name of zoological, or comparative anatomy. 
 
 Zoological anatomy is denominated philosophical or transcendental, when from the com- 
 bination and comparison of particular facts it deduces general results, and laws of orga- 
 nization. 
 
 When anatomy is confined to the examination of one species only, it receives the 
 name of special ; such as the anatomy of man, the anatomy of the horse, &c. Physio- 
 logical anatomy considers the organs in their healthy state. Pathological anatomy regards 
 them as altered by disease. 
 
 \Vhen physiological anatomy is confined to the examination of the external conforma- 
 tion of organs, that is to say, of aU their qualities which may be ascertained without di- 
 vision of their substance, it is called descriptive anatomy. If, on the contrary, it pene- 
 trates into the interior of organs, in order to determine their constituent or elementary 
 parts, it receives the name general anatomy, or of the anatomy of textures. 
 
 Descriptive anatomy informs us of the names of organs {anatomical nomenclature), 
 their number, situation, direction, size, colour, weight, consistence, figure, and relations ; 
 it traces, in fact, the topography of the hmnan body. In more than one respect, it is to 
 medicine what geography is to history. The anatomy used by painters and sculptors may 
 be regarded as one of its dependances, and may be defined to be the knowledge of the 
 external surface of the body, in the different attitudes of repose, and in its various move- 
 ments. On this subject it may be observed, that the precise determination of the ex- 
 ternal eminences and depressions may afford most important indications regarding the 
 situation and state of deeply-seated parts, and is therefore worthy the attention of the 
 physician. 
 
 Descriptive anatomy, in the sense here meant, has arrived at a high degree of perfec- 
 tion. It is to this branch that reference is made by those who affirm that nothing now 
 remains to be done in anatomy. But although descriptive anatomy may be all that the 
 surgeon requires to enable him to comprehend the lesions which most commonly fall 
 under his notice, and to perform operations, it will by no means suffice for the physician 
 or the physiologist. For their purposes, anatomical investigations must not be confined 
 to the surface, but penetrate into, and analyze the substance of organs. Now such is 
 the object of general or textural anatomy. By its means the different organs are re- 
 solved into their component tissues : these tissues, again, are reduced to their simple 
 elements, which are then studied by themselves, independently of the organs which they 
 form ; and subsequently, by considering the elementary constituents as combined in va- 
 rious proportions, the organization of even the most comphcated and dissimilar parts is 
 made manifest. 
 
 There is one species of anatomy which has of late been cultivated with the greatest 
 success. I mean the anatomy of the fatus. 
 
 The anatomy of the fatus, or the anatomy of the body at different periods of life, naiMcd 
 the anatomy of evolution, has for its object the study of the development of organs, their 
 successive modifications, and sometimes even the metamorphoses which they undergo, 
 from the time of their first appearance until they arrive at perfection. 
 
 Lastly, there is a species of anatomy to which the term of " applied anatomy''' may be 
 given, because it comprehends all the practical applications of the science to medicine 
 
 * The word Anatomy is derived from the Greek [ava, up, and rtuvai, I cut). It is, in fact, by means of 
 dissection principally that we are enabled to separate and study the different organs. But injections, desicca- 
 tion, the action of alcohol, concentrated acids, &c., are also means employed by the anatomist 
 
 A 
 
2 INTRODUCTION. 
 
 and surgery. With this view, the body is divided into regions or departments, and each 
 region into successive layers. The relation of the different layers is pointed out, and 
 in each layer the parts Avhich compose it. In a word, the constant object is the solution 
 of the following question : A region, or any part of the surface of the body being given, 
 to determine the subjacent parts which correspond to it at different depths, and their 
 order of superposition. This has generally been denominated the anatomy of regions, 
 topographical or surgical anatomy, because it has hitherto been studied only with refer- 
 ence to its uses in surgery. It may easily be shown, however, that with the exception of 
 the limbs or extremities, the anatomical knowledge of which has few applications to 
 medicine, properly so called, the study of regions is no less important to the physician 
 than to the surgeon. To give it, therefore, a name corresponding with its use, it should 
 be called medico-chirurgical topographical anatomy. 
 
 Such are the different aspects under which anatomy may be regarded. The following 
 work is essentially devoted to descriptive anatomy.* 
 
 General View of the Human Body. 
 
 Before entering on a detailed description of the munerous organs which enter into the 
 composition of the human body, it is advisable to present a rapid sketch of the whole. 
 Such general views, instead of embarrassing the mind, at once enlighten and satisfy it, 
 by exhibiting the objects of its research in their true relations, and showing the end to 
 be attained. 
 
 There is one general covering, which, like a garment, envelops the whole body, and 
 is moulded, at it were, round all its parts. This covering is the skin, of which the nails 
 and hair are dependances. The skin presents a certain number of apertures, by means 
 of which a communication is established between the exterior and the interior of the body. 
 These apertures, however, are not formed by a mere perforation or breach of continuity 
 in the skin ; on the contrary, this membrane passes inward at the circumference of 
 these openings, and having undergone certain important modifications in its structure, 
 forms the mucous membranes, a kind of internal tegument, which may be considered as 
 a prolongation of the external envelope. We might, therefore, strictly speaking, regard 
 the human body as essentially composed of a skin folded back upon itself This idea is, 
 indeed, realized in some of the inferior animals, which consist of a mere tube or canal. 
 In proportion, however, as we ascend in the scale, we find the layers which separate 
 these two teguments become more and more increased in thickness, and cavities are at 
 length formed between them. Nevertheless, however widely these membranes may be 
 separated from each other, and however different they may be in external aspect, there 
 are abundant analogies to establish unequivocally their common origin. 
 
 Under the skin there is a layer of adipose cellular tissue, which gently elevates it, fiUa 
 up the depressions, and contributes to impart that roundness of form which character- 
 izes all animals, and particularly the human species. In some parts, there are muscles 
 inserted into the skin, which are intended for its movement ; these are the cutaneoua 
 muscles. In man they are very inconsiderable, and are confined to the neck and face, 
 where they play an important part in giving expression to the physiognomy ; but in the 
 larger animals they line the whole skin, and in certain classes, of very simple organiza- 
 tion, they constitute the entire locomotive apparatus. 
 
 The superficial veins and lymphatics traverse the subcutaneous cellular tissue : tlie 
 latter, at various parts of their course, pass through enlargements denominated lymphatic 
 ganglions, or lymphatic glands, which are grouped together in certain regions. 
 
 Below the cellular tissue are the muscles, red, fleshy bundles, arranged in many layers. 
 
 In the centre of all these structures are placed the bones, inflexible columns, v/hich 
 serve for a support to all that surrounds them. The vessels and the nerves are in the 
 immediate neighbourhood of the bones, and, consequently, removed as much as possible 
 from external injury. Lastly, around the muscles and under the subcutaneous adipose 
 tissue are certain strong membranes, which bind the parts together, and which, by pro 
 longations detached from their internal surface, separate and retain in their situation 
 the different muscular layers, frequently each particular muscle : these envelopes are 
 the aponeuroses. 
 
 Such is the general structure of the limbs or extremities. 
 
 If next we examine the trunk, we find in its parietes a similar structure, but more in 
 ternally are cavities lined by thin transparent membranes, named serous, on account of 
 a liquid or serosity with which they are moistened. In these cavities are situated or- 
 gans of a complex structure, called viscera, of which we shall give a rapid enumeration 
 m an order conformable to the offices they perform in the animal economy. 
 
 The hmnan body, as well as that of other organized beings, is composed of certain 
 parts, denominated organs {bpyavov, an instrument), which differ from each other in 
 
 * Descriptive anatomy ought, in strictness, to be confined to the consideration of the external characters ol 
 organs, or what is understood by the term external conformation ; nevertheless, in order to present a complete 
 view of each organ, after having described its exterior, we shall give a short account of its texture and deveJ- 
 onment. 
 
GENERAL VIEV^'6'p¥kte' HUMAN BODY. 3 
 
 their structure and use, but are all combined, for the double purpose of the preservation 
 of the individual, and the continuance of the species. 
 
 To accomplish these purposes, the organs are distributed in a certain number of 
 groups or series, each of which has a definite end to fulfil. This end is denominated a 
 function : the series of organs receives the name of an apparatus. Of those necessary 
 for the preservation of the individual, some are designed to place him in relation with 
 external objects, and these constitute the apparatus of relation : the others are destined 
 to repair the loss which the parts of the body are constantly suffering ; they form the 
 apparatus of nutrition. 
 
 The apparatus of relation may be subdivided into two classes : 1. The apparaius of 
 sensation. 2. The apparatus of motion. 
 
 Apparatus of Sensation. — The apparatus of sensation consists, 1. Of the organs of 
 sense ; 2. Of the nerves ; 3. Of the brain and spinal cord. 
 
 The organs of the senses are, 1. The skin, which possesses sensibility, the exercise 
 of which constitutes tact. The skin being placed under the direction of the will, and 
 rendered mobile in consequence of the peculiar mechanism of the human hand, is called 
 the organ of touch. 2. The organ of taste, the seat of which is in the cavity of the 
 mouth, that is, at the entrance of the digestive canal. 3. The organ of smell, placed in 
 the nasal fossee, the commencement of the respiratory passages, by which we are en- 
 abled to recognise the odorous emanations of bodies. 4. The organ of hearing, con- 
 structed in accordance with the principles of acoustics, and placed in relation with the 
 vibrations of the air. 5. TTie organ of sight, which bears relation to the hght, and ex- 
 hibits a construction in harmony with the most important laws of dioptrics. 
 
 The organs of sense receive impressions from without. Four of them occupy the 
 face, and are, therefore, placed in the vicinity of the brain, to which they transmit im- 
 pressions with great rapidity and precision ; and that organ seems, in its turn, to extend 
 into them, so to speak, by means of the nerves. Indeed, the impressions received by 
 the external organs would be arrested in them, were it not for certain conductors of 
 such impressions : these conductors are the nerves — white, fasciculated cords, one ex- 
 tremity of which passes into the organs, while the other is connected to the spinal mar- 
 row and the brain, which are the central parts of the nervous system, the nerves con- 
 stituting the peripheral part. 
 
 Apparatus of Locomotion. — The apparatus of locomotion consists, 1. Of an active or 
 contractile portion, the muscles. These are terminated by tendons, organs of a pearly 
 white colour, which direct upon a single point the action of many forces ; 2. Of a pas- 
 sive portion, the bones, true levers, which constitute the framework of the body, and tlie 
 extremities of which, by their mutual contact, form the articulations : in the latter we 
 perceive (a) the cartilages, compressible, elastic substances, which deaden the violence 
 of shocks, and render the contact uniform ; (jb) an unctuous liquid, the synovia, secreted 
 by membranes denominated synovial : this liquid performs the office of the grease em- 
 ployed in the wheel- work of machinery ; (c) bands or ligaments, which maintain the con- 
 nexion of the bones. 
 
 Such is the apparatus designed to establish the relation between man and external 
 objects. 
 
 Apparatus of Nutrition. — The apparatus which performs in the human body the im- 
 portant office of nutrition consists of the following parts : 
 
 A. The digestive apparatus, which consists essentially of a continuous tube or canal, 
 denominated the alimentary canal. This canal has not the same form and structure 
 throughout the whole extent : on the contrary, it is composed of a series of vei7 dissim- 
 ilar organs, all, however, contributing to the formation of one common passage. These 
 organs are, 1. The mouth; 2. The pharynx; 3. The msophagus, or gullet; 4. The stom- 
 ach ; 5. The intestines ; which are farther subdivided into the small intestines, consisting 
 of the duodenum, jejunum, and ileum, and the large intestines, comprising the cacum, colon, 
 and rectum. 
 
 To this long tube, the greater part of which is contained in the abdomen, where it 
 forms numerous reduplications, are annexed, 1. The liver, a glandular organ, whose 
 office it is to secrete the bile, and which occupies the superior and right portion of the 
 abdomen ; 2. The spleen, whose functions are involved in great obscurity, but which 
 may, perhaps, be termed an appendix to the liver, on the left side ; 3. The pancreas, which 
 pours a fluid into the duodemmi, by an orifice common to it and the biliary duct. 
 
 B. On the internal surface of the digestive canal, and particularly that portion of it 
 which bears the name of the small intestine, certain vessels open by numerous orifices 
 or mouths,* and carry otfthe nutritive fluids prepared by the process of digestion : these 
 are the chyliferous or absorbent vessels, which are also called lacteal vessels, on account of 
 the white, milky aspect presented by their contents while absorption is going on. The 
 absorbent appai'atus consists, also, of another set of vessels denominated lymphatics, be- 
 cause they contain a colourless liquid named lymph, which they collect from a,H parts ol 
 
 * (This must not be understood literally. See account of the lacteals, infni.l 
 
4 INTRODUCTION. 
 
 the body. All the absorbent vessels, of whatever order they may be, traverse at differ^ 
 ent parts of their course certain grayish bodies, called lymphatic gangUmis or glands, and 
 finally terminate in the venous system. 
 
 C. The venous system arises from all parts of the body : it takes up, on the one hand, 
 all those matters which, having been employed a sufficient time as part of the body, must 
 be eliminated from it ; and, on the other hand, all those substances which are carried into 
 the system, to contribute to its reparation : it is composed of vessels denominated veins 
 which at various distances are provided with valves, and at last unite in forming two 
 large veins called vena cavce, of which one, the superior, receives the blood from the upper 
 part of the body ; the other, the inferior, brings back that which has circulated in the 
 lower portion. 
 
 These two venae cavae terminate in the central organ of the circalation, the heart, a 
 hollow muscle, containing four contractile cavities : two on the right side, the right au- 
 ricle and ventricle, and two on the left, the left auricle and ventricle. 
 
 D. Next to these in order of function is the respiratory apparatus, composed of two 
 spongy sacs, placed on each side of the heart, and occupying almost the whole of the 
 chest : these are the lungs. They receive the air from a common tube, the trachea, 
 which is surmounted by a vibratile organ, the larynx, which opens externally by the nose 
 and mouth, and constitutes the organ of voice. 
 
 E. From that cavity of the heart which is called the left ventricle, arises a large ves- 
 sel, the aorta : this forms the principal and primitive trunk of the whole class of vessels 
 named arteries, whose office it is to convey red blood to all parts of the body, to main- 
 tain their heat and life. 
 
 F. There still remains one other portion of the nutritive system, the urinary appara- 
 tus, consisting of, 1. The kidneys, organs which secrete the urine : 2. The ureters, by 
 means of which the urine, as soon as secreted, passes off into a spacious receptacle, the 
 bladder, from whence it is at intervals expelled along a passage which has received the 
 name of urethra. 
 
 Apparatus of Reproduction. — ^The apparatus above mentioned is destined for individual 
 preservation : the organs which secure the continuance of the species constitute the 
 generative or reproductive apparatus. They differ in the male and in the female. 
 
 In the male they are, 1 . The testicles, which prepare the spermatic or fecundating fluid , 
 2. The vasa deferentia, tubes which transmit this fluid from the testicle where it is se- 
 creted to the vesiculse seminales ; 3. The vesicula. seminales, or receptacles of semen ; 
 4. The cjaculatory ducts, through which the semmal fluid passes into the urethra ; 5. The 
 prostate and Cowpefs glands, glandular appendages of the organs for the transmission 
 of the semen ; 6. The penis, by means of which the fecundating fluid is conveyed into 
 the interior of the genital organs of the female. 
 
 The generative apparatus in the female is composed of the following organs : 1. The 
 ovaries, the function of which is to produce, or keep in readiness, the ovulum or germ ; 
 2. The uterine tubes, which transmit the germ, when fecundated, to the uterus ; 3. The 
 uterus or womb, in which the product of conception remains and is developed during the 
 period of gestation ; 4. The vagina, a canal which permits the passage of the foetus at its 
 final expulsion ; 5. As appertaining to the system should be mentioned the mammary 
 glands, which secrete the milk destined for the nourishment of the new-bom infant. 
 
 Genkral Plan of the Work. 
 
 There are two methods by which the numerous facts that come within the range of 
 anatomy may be explained. The different organs may be studied in their order of super- 
 position, or in the topographic order, a capite ad calcem ; in this way the most dissimilar 
 parts are brought together, while others are separated which have the greatest analogy ; 
 or they may be considered in a physiological order, i. e., an order founded upon the same 
 grounds as serve for the classification of functions. This is clearly the most rational, 
 because it has the incontestable advantage of preparing for the study of the functions by 
 that of the organs. It may be easily seen, however, that this physiological arrangement 
 should be modified according to the relative difficulty in the study of the different parts 
 of the body ; for the great aim in a work of instruction should be to conduct the mind, by 
 degrees, from simple and easy objects to those which are more complicated. It is for 
 this reason that the consideration of the nervous system, which, in strict accordance 
 with physiological arrangement, should be placed near to that of the locomotive appara- 
 tus, is deferred. The object proposed has been to adopt an arrangement which would, 
 as far as possible, reconcile both these views, and, at the same time, be compatible with 
 the greatest economy of subjects for dissection ; and this appears to be secured by the 
 method generally adopted, at least with a few slight modifications. 
 
 The following table presents a view of the general plan of this work : 
 
 f 1 . Of the bones— Osteology. 
 
 , • . , , ^ 1 2. Of the articulations — SyndeHHology. 
 
 1. Apparatus of locomotion S 3. Of the muscles-Myology. 
 
 14. Of the aponeuroses — Aponeurolog . 
 
GENERAL OBSERVATIONS. 
 
 B. Apparatus of digestion, apparams of respiration, ) Splanchnoloffv 
 genito-urinary apparatus ....)' 
 
 f Heart T 
 
 3. Apparatus of the circulation .... 'S Veins'*^ [ >Angeiology. 
 
 I Lymphatics J 
 
 f Organs of the senses'! 
 
 4, Apparatus of sensation and innervation . , < jj^^^ ""'^ ' ' > Neurology. 
 
 LNerves . . .J 
 
 APPARATUS OF LOCOMOTION. 
 
 OSTEOLOGY. 
 
 OF THE BONES IN GENER.4.L. 
 
 The Bones — Importance of their Study. — General View of the Skeleton. — Number of the 
 Bones. — Method of Description. — Nomenclature. — Situation in general. — Direction. — Size, 
 Weight, and Density of Bones. — Figure. — Distinction into Long, Broad, and Flat Banes. 
 — Regions of Bones. — Eminences and Cavities. — Internal Cofiformation. — Texture. — De- 
 velopment of Osteogeny. — Nutrition. 
 
 The bones are parts of a stony hardness, but yet organized and living. They serve 
 as a support to all other parts of the body, are a means of protection to many, and aiford 
 points of attachment to the muscles, in the midst of which they are situated. All the 
 hard parts of the body, however, are not bones. The fundamental character of a bone 
 consists in its being at once hard and organized. As the bones receive vessels for the 
 purpose of nutrition at every part of their surface, they are surrounded on all sides by a 
 membrane which is fibrous and vascular, named the Periosteum (nepl, around ; dareov, 
 a bone). 
 
 According to this definition, the teeth, horns, nails, and, in articulated animals, the ex- 
 terior skeleton, are not to be considered as bones, but merely ossiform concretions. We 
 may add, that true bones belong exclusively to vertebrated animals. 
 
 The study of the bones constitutes Osteology, which may be regarded as the basis of 
 anatomy, for without a knowledge of the bones it is impossible to become acquainted 
 with the muscular insertions, or the exact relations between the muscles, nerves, vis- 
 cera, and, above all, the vessels, for which the bones afford the anatomist invariable 
 points of reference. Osteology has, therefore, ever since the time of the Alexandrian 
 school, formed the commencement of the study of anatomy. 
 
 In the present day, the transcendental anatomists have particularly engaged in the 
 study of the osseous system, doubtless on account of the facility with which it may be 
 investigated ; and from their labours, though in many respects speculative, a more ac- 
 curate knowledge has been obtained of some of the nicer points of osteology, which had 
 scarce attracted notice from the older anatomists. 
 
 Lastly, from the admirable researches of Cuvier respecting fossil animals, osteology 
 has become one of the most important bases of comparative anatomy and geology. By 
 the study of bones the anatomist has been enabled to determine genera and species, no 
 longer existing on the face of the globe, and to give, as it were, new life to these old and 
 disjointed relics of the antediluvian animal kingdom. Thus the fossil bones, deposited 
 in an invariable order of superposition in the crust of the earth, have been transformed 
 into monuments more authentic than historical records. 
 
 General View of the Skeleton. — ^The bones form a system or whole, of which the different 
 parts are contiguous, and united to each other. The only exception to this rule is the 
 OS hyoides, and yet the ligaments by which it is connected with the rest of the system 
 are evidently the representatives of the osseous pieces, which in the lower animals con- 
 nect this bone with the temporal. 
 
 The assemblage of the bones constitutes the skeleton. It is called a natural skeleton 
 when its different parts are connected by their own ligaments ; an artificial skeleton, on 
 the other hand, is one of which the bones are joined together by artificial connexions, 
 such as metallic wires, &c. 
 
 The result of this union is a symmetrical and regular structure, essentially composed 
 of a central column, denominated the vertebral column or spine, which terminates superi- 
 orly in a considerable enlargement, the cranium, and inferiorly in certain immovably 
 united vertebrae, which constitute the sacrum and coccyx. To this column the following 
 appendages are attached : 1. In front of and below the cranium, a complicated osseous 
 structure, the face, divided into two maxillce, the superior and inferior. 2. On each side 
 twelve bony arches, flexible, elastic, and curved — the ribs, which are united in front to 
 another column, the sternum. These parts, taken together, form the thorax. 3. Four 
 prolongations, called limbs or extremities : two superior, or thoracic, as they are termed, 
 because they correspond with the chest or thorax ; and two inferior or pelvic, so named 
 
g 6 OSTEOLOGY. 
 
 on account of their connexion with the basin or pelvis, but better uamed^ abdominal a 
 tremities. The thoracic and abdominal extremities are evidently modifications of the 
 same fundamental type, and are essentially composed of the same number of analogous 
 parts, viz. : 1. An osseous girdle, the superior constituted by the bones of the shoulder, 
 the inferior by the pelvis. 2. A part Avhich may be in some measure regarded as the 
 body of the limb, viz., the humerus, in the thoracic extremity, the femur in the abdominal. 
 
 3. A manubrium or handle, to use an expression of Galen, above the forearm, below 
 the leg. 4. Lastly, digitated appendages which form the extremities, properly so called, 
 viz., the hand and the /oof. 
 
 Number of the Bones. — Authors do not agree respecting the number of the bones. 
 Some, for instance, describe the sphenoid and the occipital as forming only one bone, 
 while most anatomists consider them two distinct bones. Some admit three pieces in 
 the sternum, which they describe separately. Many, after the example of the older 
 writers, divide the haunch into three distinct bones — ^the pubes, the ischium, and the 
 ileum : others recognise five pelvic or sacral vertebrae ; three or five parts of the os 
 hyoides ; and, lastly, the ossa sesamoidea and the ossa wormiana- are omitted by some, 
 but by others are reckoned in the enumeration of the bones. 
 
 The ideas of certain modem authors with respect to the development of the bones, in- 
 stead of dispelling the uncertainty which attaches to the enumeration of the parts of the 
 skeleton, have tended not a little to increase the confusion, because many of them have 
 made no distinction between bones, properly so called, and pieces of ossification. All 
 doubt, however, in this respect will cease, provided we consider as distinct bones only 
 those portions of the skeleton which are separable at the time of complete development. 
 
 The time at which the osseous system arrives at its perfect development is between 
 the twenty-fifth and thirtieth year. 
 
 According to these views, we may count in the human body 198 bones, viz. : 
 
 Vertebral column, including the sacrum and coccyx .... 26 
 
 Cranium 8 
 
 Face 14 
 
 Os hyoides 1 
 
 Thorax (ribs, sternum) 25 
 
 Superior extremities, each 32, viz., shoulder, arm, forearm, and hand 64 
 
 Inferior extremities, each 30, viz., pelvis, thigh, leg, and foot . 60 
 
 198 
 This enumeration does not include the ossa wormiana, nor the ossa sesamoidea, among 
 which we include the patella. 
 
 Of these 198 bones, 34 only are single : all the others are in pairs, which reduces the 
 number to be studied to 116. 
 
 Before proceeding to examine each piece of the skeleton in particular, we shall state 
 the method we intend to pursue in the description. The chief points embraced by de- 
 tailed descriptions of a bone are, 1. Its name; 2. Its general situation; 3. Its direction ; 
 
 4. Its bulk and weight ; 5. Its figure ; 6. Its regions ; 7. Its relations ; 8. Its internal 
 conformation ; 9. Its intimate texture ; 10. Its development. 
 
 Nomenclature. — Osteological nomenclature has many imperfections. Persuaded of 
 the importance of a suitable choice of language in the study of all the sciences, some 
 anatomists have endeavoured to introduce reforms, but with little success, the old de- 
 nominations being still for the most part retained. From these modern systems of no- 
 menclature we shall adopt only such terms as Eire strikingly appropriate, or such as have 
 already been sanctioned by usage. We may here observe that the denominations of 
 bones have been derived, 1. From their situation ; as the frontal, which is so called be- 
 cause it is situated in the forehead : 2. From a resemblance, usually very obscure, to some 
 well-known object, as the bones named tibia, scaphoid, malleus, incus, stapes ; or to some 
 geometrical figure, as the cuboid : 3. From their size ; as the os magnum of the carpus, 
 and the small bones or ossicula of the ear : 4. From some circumstance of their external 
 conformation ; as the cribriform or ethmoid bone, the unciform or hooked bone : 5. From 
 the name of the author who first most carefully described them ; as the ossicles of Ber 
 tin, of Morgagni — swings of Jngrassias, &c. 
 
 General Situation of Bones. — The situation of a bone is determined by comparing the 
 place which it occupies with that occupied by other bones of the skeleton. In order to 
 make this comparison, the skeleton is supposed to be surrounded by certain planes, 
 which are thus denominated : 1 . A7i anterior plane, passing before the forehead, the 
 breast, and the feet ; 2. A posterior plane, passing behind the occiput and the heels ; 3. A 
 superior plane, placed horizontally above the head ; 4. An inferior plane, which passes be- 
 low the soles of the feet ; 5 and 6. The two lateral planes, which complete the sort of 
 case or parallelepiped with which we suppose the skeleton to be surrounded. Lastly, 
 the skeleton being symmetrical, i. e., exactly divisible into two similar halves, we admit 
 a seventh imaginary plane, the median or antero-posterior, separating these two halves. 
 By the term median line is understood an imaginary line traced so as to mark exteriorly 
 the division of all the symmetrical bone" of the skeleton into two similar halves. 
 
GENEEAL OBSERVATIONS. 7 
 
 These points being understood, nothing is more easy than to determine the position 
 of a bone. If it approach nearer to the anterior plane than others with which it is com- 
 pared, it is said to be anterior to them ; if it be nearer the posterior plane, it is said to be 
 posterior to them. Let us take, for example, the malar or cheek bones. With respect 
 to the whole face, they are placed at the anterior, superior, and in some degree the lateral 
 part; relatively to the neighbouring bones, they are situated, 1. Below the frontal; 2. 
 Above and a little external to the maxillary ; 3. Before the great wings of the sphenoid 
 and the zygomatic process of the temporal. 
 
 Direction of Bones. — The direction of a bone is absolute or relative. The absolute di- 
 rection is expressed by the terms straight, curved, angular, or twisted ; in a word, it is the 
 direction of a bone considered by itself, or independently of its situation in the skeleton. 
 The long bones are never quite straight : sometimes they present a shght degree of cur- 
 vature, as the femur ; sometimes their extremities are curved in opposite directions, 
 like the letter S, as the clavicle : sometimes, again, they are twisted upon their own 
 axes, as the humerus, the fibula, &c. 
 
 The relative direction is determined by reference to .the planes which circumscribe 
 the skeleton. Viewed in this manner, a bone is vertical, horizontal, or oblique. It is 
 needless to enter into any explanation of the terms vertical and horizontal ; but with re- 
 gard to the oblique direction, it may be stated that this is determined by the respective 
 situations of its two extremities. For example, a bone is oblique when one extremity 
 approximates the superior, the median, and the posterior planes, while the other ap- 
 proaches nearer to the inferior, lateral, and anterior planes ; such a bone is said to be 
 obhque from above downward, from within outward, and from behind forward. It is easy 
 to see that in this way the situation of a bone relatively to the different planes may be 
 determined with the greatest exactness. It should be observed, that in describing the 
 direction of a bone, we should always set out from the same point. Thus, if the direc- 
 tion of a bone from above downward is spoken of in determining its obhquity from be- 
 fore backward, and from vrithin outward, we should always commence with the supe 
 rior extremity. 
 \^ Size, Weight, and Density of Bones. — The size of a bone may be measured by the ex- 
 /* tent of its three dimensions ; but as an exact estimate is not in general required, it is 
 sufficient to indicate the voliftne of each bone relatively to others, whence has arisen 
 the division of bones into great, middle-sized, and small ; a distinction, however, altogeth- 
 er vague and futile, since from the largest to the smallest bones there is so regular a 
 gradation that the limits assigned must be quite arbitrary. 
 
 The weight, or the mass of the skeleton compared with the rest of the body, the weight 
 of each bone, and the comparative weight of different bones, are points of little inter- 
 est ; such, however, is not the case with the specific weight or density of bones. 
 
 In respect of density, viz., the number of molecules in a given volume, the bones are 
 the heaviest of all organs. The truth of this assertion is by no means contradicted by 
 the lightness of certain bones, which is only apparent, and which is caused by vacant 
 spaces or cells in their substance. This density varies in different kinds of bones, in 
 bones of the same kind, and even in different parts of the same bone. Thus, in the long 
 bones, the greatest density is in the middle : the extremities of the long bones and the 
 short bones have a much lower density. The broad or flat bones hold a middle place 
 between the shaft of long bones and the short bones. Of these broad bones, those of the 
 cranium are heavier than those of the pelvis. Age has a remarkable influence upon the 
 specific weight of bones. It has been said that the bones of the aged are specificcdly 
 more heavy than those of the adult, just as the bones of the adult are specifically heavi- 
 er than those of the infant ; and this assertion appears the more probable, from it being 
 generally admitted, as a law of organization, that the phosphate of lime increases in 
 bones with the progress of age ; and it is well known that the weight of bones depends, 
 in part, on the presence of this calcareous phosphate. But on this point, as on many 
 others, experience has refuted these preconceived opinions. Thus, it is certain that the 
 specific, as well as the absolute weight of bones, is much less considerable in the old 
 person than in the adult ; and this difference depends upon the loss of substance which 
 the bones undergo, in common with all other tissues, during the progress of age : thus, 
 in aged subjects, the walls of the cylinder of the long bones are remarkably diminished 
 in thickness, while the medullary cavity is proportionally increased. We rnay even af- 
 firm, with Chaussier, that the medullary cavity of the shaft of long bones has a greater 
 diameter, in proportion as the individual is advanced in age. In like manner, the cells 
 of the spongy tissue become much larger, and their w-alls acquire an extreme tenuity. 
 It may, nevertheless, be contended, that the weight of the osseous fibre, or, rather, of 
 the osseous molecules of the old people, is gieater, comparatively, than that of the same 
 parts in the adult ; and this presumption is ahnost converted into certainty by chemical 
 iinalysis, which shows an excess of phosphate of lime in the bones of the aged : to re- 
 move all doubts upon this point, it would he necessary to grind an adult bone and an old 
 one, and to weigh in the balance an equal bulk of each powder. In this way the contra- 
 dictory statements of certain authors might be reconciled. 
 
-K 
 
 8 OSTEOLOGY. 
 
 The increasing fragility of bones, and the consequent frequency of fractures in old age, 
 are CEisily explained, since along with the accumulation of phosphate of lime, which di- 
 minishes the elasticity while it increases the brittleness, there occurs a diminution of 
 bulk, and, consequently, there is less resistance. It is with respect to the quantity of 
 calcareous phosphate alone that the osseous system can be said to preponderate in old age. 
 
 Shape of Bones. — The shape of a bone is determined, 1. By comparison either with 
 different known objects, or with geometrical figures : thus the frontal bone has been 
 compared to the scallop-shells of pilgrims, the sphenoid to a bat with extended wings, 
 &c. It may be readily conceived that, notwithstanding its want of exactness, this meth- 
 od of comparison, so familiar to the ancients, cannot be altogether proscribed. The 
 comparison of bones whose forms are so irregular with the regular solid figures of which 
 geometry treats is no less inaccurate than the preceding ; nevertheless, we shall con- 
 tinue, like other anatomists, to speak of the short bones as cuboidal, the shafts of long 
 bones as being prismatic and triangular, the lower maxdlaj parabolic, &c. We shall 
 speak of spheres, of cones, of ovoids, of cylinders, &c. 
 
 2. The symmetry or want of synmietry of bones is a fundamental point in the deter- 
 mination of their figure : thus, some bones are divisible into two halves exactly resem- 
 bling each other ; these are the syimnetrical or azygos bones, also called median, be- 
 cause they always occupy the middle line. The others can not be divided into two sim- 
 ilar parts : these are the asymmetrical bones, called also lateral or corresponding, because 
 they are always in pairs, and situated on opposite sides of the median line. 
 
 3. The figure of a bone comprehends, also, the proportion which its three dimensions 
 bear to each other. When the three dimensions, length, breadth, and thickness, are 
 nearly equal, the bone is said to be short ; when the length and breadth are almost the 
 same, and both greater than the thickness, the bone is called broad or fiat. Lastly, the 
 predominance of one dimension over the two others constitutes the character of long 
 bones. The distinction here drawn, however, is not altogether exact, because there are 
 certain mixed bones which partake at the seime time of the character of the long and the 
 broad bones. 
 
 Some general observations upon the three great classes will not be out of place here, 
 as they will be applicable in the description of the individual bones. 
 
 Ge?ieral Characters of Long, Flat, and Short Bones. 
 
 Of Long Bones. — The long bones are situated in the extremities, in the centre of which 
 they form a set of pillars or levers placed upon each other. The bones of the abdominal 
 extremities are generally longer and larger than those of the thoracic. The longest 
 bones are in the upper part of the limbs ; it may be said, indeed, that the length of bones 
 is in the direct ratio of their proximity to the trunk. The diameter of the long bones is 
 smallest in their middle. From this part, as from a centre, they gradually increase in 
 volume, and at their extremities are much enlarged, so as to present a diameter doubld 
 or treble that of the shaft. Every long bone, therefore, presents a biconical form, i. e., 
 is shaped like two cones united by their summits. 
 
 A long bone consists of a shaft and extremities. The shaft of the long bones is almost 
 always prismatic and triangular ; so much so, that in this respect the bones seem to be 
 an exception to the general rule of organized bodies, which have usually a rounded form, 
 and to approach nearer that of the mineral kingdom, the characteristic shape of which 
 is angular. 
 
 The extremities of long bones are enlarged, that they may serve, 1. For articula- 
 tions ; 2. For the insertion of ligaments and muscles ; 3. For the reflection of tendons, 
 the direction of which they alter. Each extremity presents a smooth articular surface, 
 covered with cartilage in the fresh state, and not perforated by any foramina, and a 
 non-articular portion, rough, pierced with apertures, and covered with eminences and 
 depressions. 
 
 Of Broad or Flat Bones. — These bones, intended to form the parietes of cavities, are 
 more or less curved, and present for consideration a circumference and two surfaces ; 
 the internal concave, the external convex. No single broad bone constitutes a cavity ; 
 there are always a certain number united for this purpose. Some broad bones are alter- 
 nately concave and convex on the same surface, as the haunch bones. In flat or broad 
 bones there is no accurate correspondence between the inequalities, ridges, or depres- 
 sions of the two surfaces. Thus, the iliac portion of the haunch bones, instead of pre 
 senting a convexity on the inner surface, to correspond with the external iliac fossa, is 
 hoUowed out into another depression, the internal iliac fossa. In like manner, in the 
 cranium certain impressions and eminences exist on the internal surface, whUe the ex- 
 ternal is uniformly convex, and almost smooth. The parietal, and even the occipital 
 protuberances, would be twice or three times more prominent if the interior concavity 
 were faithfully represented by a corresponding external prominence, and if this concav- 
 ity were not in a great measure hollowed out from the substance of the bone. 
 
 The circumference of broad bones being intended either for articulations or for inser- 
 tions, is for this purpose greatly thickened. Thus the parietal bones, which are very 
 
GENERAL OBSERVAT[ONS. 9 
 
 thin at their centre, become considerably thicker at the circumterence. The broad 
 bones present at their circumference sometimes a simple enlargement, when it is in- 
 tended for muscular insertions only ; for example, the haunch bones : sometimes indent- 
 ations of various kinds, and sinuosities, when it is to serve the purpose of articulation ; 
 for instance, the bones of the cranium. 
 
 Of Short Bones. — These are principally met with in the vertebral column, the carpus, 
 and the tarsus ; in fact, wherever great solidity is required in connexion with slight mo- 
 bility : several of them are always grouped together ; their form is extremely irregular, 
 but generally cuboid ; they have also numerous facettes for articulation. The non-artic- 
 ular portion is rough, for the insertion of ligaments and tendons. 
 
 Regions of Bones. — There are so many objects to be considered on the surface of a 
 bone, that it is necessary, in order to prevent the omission of any essential detail in 
 the description, to divide the surface into a certain number of parts or regions, which 
 should be successively examined. These different parts or regions have been denom- 
 inated faces, borders, and angles. Thus, in the prismatic and triangular shafts of long 
 bones, there are three faces and three borders to be considered ; in the flat bones, two faces 
 and a circumference, which is again subdivided into borders and angles formed by the meet- 
 ing of these borders. There are six faces in the short bones. These faces and borders are 
 named sometimes, from their situation, superior, inferior, anterior, posterior, &c. ; some- 
 times from the parts which they contribute to form, such as the orbital and palatine fa- 
 ces of the superior maxillary bone ; sometimes from their relations to other parts, as 
 the cerebral and cutaneous face of the bones of the cranium, the frontal, occipital, and tem- 
 poral borders of the parietal bones. When the borders give insertion to a great number 
 of muscles, it has been deemed advisable to divide these into three parts or parallel 
 lines : the middle is then called the interstice, and the two lateral are named lips, the in- 
 ternal and external lip ; the superior border of the haunch bone, and the linea aspera of 
 the femur, are examples. 
 
 Eminences and Cavities of Bones. — ^The bones present certain eminences and cavities, 
 of which it is proper to take a general survey in this place. 
 
 Eminences of Bones. — The osseous eminences or processes were divided by the an- 
 cients into two great classes, apophyses and epiphyses, distinguished by the difference 
 of their mode of development. According to their view, some of these eminences arise 
 from the body of the bone, appearing to be nothing more than prolongations or vege- 
 tations of its substance : these they called apophyses ; others, on the contrary, are 
 formed by separate osseous centres or nuclei, which make their appearance at various 
 times during the process of the development of bone : to these they gave the name of 
 epiphyses. This distinction, however, founded upon incomplete observation, has been 
 totally rejected, since the researches of M. Serres on Osteogeny have rendered it evi- 
 dent that almost aU the osseous eminences are developed from isolated nodules ; so 
 that an eminence, which at one time is an epiphysis, becomes afterward an apophysis. 
 If, therefore, the majority of eminences are formed from separate osseous points, the dif- 
 ference between them can apply only to the relative periods at which they become uni- 
 ted to the body of the bone. 
 
 A far more important distinction is that by which the eminences are divided into 
 articular and non-articular. 
 
 The articular eminences have received different names. 1. They are called dentic- 
 ulations when they form angular eminences resembling the teeth of a saw ; these are 
 best seen in the bones of the cranium. This kind of eminence is employed only in im- 
 movable articulations. 
 
 The others belong to joints which admit of motion, and have received the folloMing 
 names : 1. They are called heads when they represent a portion of a sphere supported 
 by a more contracted portion, to which the name of neck is given ; for example, the head 
 and neck of the femur. 2. The term condyle is applied to them when they resemble an 
 elongated head, or a portion of an ovoid cut parallel to its greatest diameter ; for exsim- 
 ple, the condyles of the inferior maxilla. 
 
 The non-articular eminences are, for the most part, designed for muscular insertions. 
 Their appellations are in general derived from their shape. Thus, they are denominated, 
 
 1 . Prominences. When they are but slightly elevated, smooth, and almost equally ex- 
 tended in all directions ; as the parietal and frontal eminences. 
 
 2. Mamillary Processes. When they resemble papillas ; for instance, the mamillary 
 processes of the internal surface of the bones of the cranium. 
 
 3. Tuberosities. When they are of a larger size, round, but uneven ; for example, the 
 occipital protuberance, the bicipital tuberosity (or tubercle) of the radius. 
 
 4. Spines or Spinous Processes. When, from their acuminated, but generaUy rugged 
 form, they bear some resemblance to a thorn ; as the spine of the tibia, the spinous pro- 
 cesses of the vertebrae. 
 
 5. Lines. When their length greatly exceeds their breadth ; as the semicircular lines 
 of the occipital bone. When these lines are more prominent, and covered with asper- 
 ities, they receive the name of linear asperae ; as the hnea aspera of the femur. 
 
 B 
 
10 OSTEOLOGY. 
 
 6. Crests. When they are elevated, and have a sharp edge ; as the external and inter 
 nal crest of the occipital bone, the crest of the tibia. One of these eminences has been 
 denominated the crista galli, because it bears some resemblance to the comb of a cock. 
 
 7. The term apophyses (or processes) has been retained for those eminences which are 
 of a certain size, and appear to form, as it were, a little bone superadded to that from 
 which they spring ; they are distinguished, for the most part, by epithets derived from 
 their shape. Thus, the clinoid processes of the sphenoid are so called from their supposed 
 resemblance to the supporters of a bed {kMvjj, a bed ; ehhc, shape). Pterygoid processes 
 are those wliich are like wings (Trrcptf, a wing). Mastoid, such as resemble a nipple 
 (fiaardc, manrmia). Zygomatic, such as have the form of a yoke {Cvyoc, a yoke). Styloid, 
 such as are like a style. Coronoid, such as are shaped like one of the angular projec- 
 tirns of a diadem.* Odontoid, such as resemble a tooth ; as the odontoid process of the 
 second cervical vertebra. Coracoid, such as have the form of a raven's beak («dpaf, a 
 raven) ; as the coracoid process of the scapula. Malleoli, euch as are like a hammer 
 (malleus, a hammer). 
 
 Some processes have received names, 1 . From the parts they contribute to form — 
 orbitar processes, malar processes, olecranon {uTiivrj, the elbow ; Kpdvov, head) : 2. From 
 their direction ; as the ascending process of the superior maxilla : 3. From their uses ; 
 as the trochanters (jpoxau, to turn), because they serve for the insertion of muscles, 
 which rotate the leg on its own axis. 
 
 No part of the language of osteology, perhaps, is more faulty than the nomenclature of 
 the eminences. Thus, how unlike is the spine of the scapula to the spinous processes 
 of the vertebrae, or the styloid process of the temporal to the diminutive projection call- 
 ed styloid of the radius ! Many eminences which perform analogous offices have re- 
 ceived different names : thus, the eminences of the humerus, which give attachment to 
 its rotating muscles, are called the great and small tuberosities ; while the correspond- 
 ing parts of the femur have been denominated trochanters. While, therefore, we retain 
 the names consecrated by usage, we shall be careful to point out the more rational terms 
 substituted by modern anatomists, and particularly by Chaussier. 
 
 The size of the eminences of insertion is in general proportional to the number and 
 strength of the muscles and ligaments which are attached to them. To be convinced 
 of this fact, it is only necessary to compare the male and female skeleton, or that of a 
 man of sedentary habits and that of a person devoted to athletic exercises. This re- 
 markable correspondence between the size of osseous eminences and the strength of the 
 muscles which are inserted into them, has given rise to the opinion that these eminences 
 are formed by muscular traction. It is easy to refute this notion, and without entering 
 into details which belong to general anatomy, we shall prove, by facts, that the osseous 
 projections enter into the primordial plan of organization, so much so, that they would 
 have doubtless existed, even though the muscles had never exercised any traction upon 
 the bones. I have twee had occasion to dissect the thoracic extremities of individuals, 
 who, in consequence of convulsions during their earliest infancy, had suffered complete 
 paralysis of these parts. The limb affected had scarcely the proportions of that of a 
 child of eight or nine years, while the opposite hmb was perfectly developed. Never- 
 theless, in this atrophied limb, the smallest as well as the largest projections were per- 
 fectly marked. Moreover, very powerful muscles are often inserted into cavities, as, 
 for instance, the pterygoid cavity of the sphenoid. 
 
 Cavities of Bones. — Besides the great cavities of the skeleton, cavities in the formation 
 of which many bones concur, and which are destined to lodge and defend the organs 
 most important to Ufe, there are a great number of smaller excavations formed in the 
 substance of the bone itself. 
 
 These cavities, like the eminences, are divided into two great classes, articular and 
 non-articular. The articular cavities have received different names. 1. The term cotyloid 
 designates the articular cavity in the haunch bone, because it is deep and round, like a 
 vessel known by the ancients under the name of kotvIt]. 2. The name glenoid (from 
 y7ir)vr]) is applied to many articular cavities, which are more shallow ; for example, the 
 glenoid cavity of the scapula, the glenoid cavity of the temporal bone. 3. The term al- 
 veoli has been assigned to the cells or sockets in which the roots of the teeth are lodged. 
 It is not correct, however, to consider as an articulation the union of the teeth with the 
 jaws, because, as we shall afterward show, the teeth are not true bones. 
 
 The non-articular cavities are to be considered with reference both to their figure and 
 their uses. From their figure, they have received the following denominations : 1. Fossa, 
 or pits, are cavities largely excavated, wider at the margin than at the bottom ; e. g., the 
 parietal fossaj. 2. Sinuses are cavities with a narrow entrance ; as the sphenoidal sinus, 
 maxillary sinus, &c. 3. The term cells is applied when the cavities are small, but nu- 
 merous, and communicating with each other ; as the ethmoidal cells, &c. 4. Channels 
 {gutters) are cavities which resemble an open semi-cyhndrical canal ; as the channels for 
 the longitudinal and lateral sinuses of the scull. 5, These take the name of grooves 
 
 * [Also from Kopiivt], a wow — like a crow's beak.] 
 
GENERAL OBSERVATIONS. 11 
 
 (coulisses) when they are lined by a thin layer of cartilage, for the passage of tendons ; 
 as the bicipital groove of the humerus. The terra pulley or trochlea is applied to grooves 
 which have their two borders also covered with cartilage. 6. Furrows are superficial 
 impressions, long, but very narrow, and intended for the lodgment of vessels or nerves, 
 as the furrows for the middle meningeal artery. 7. When more deeply excavated than 
 the last, and angular at the bottom, they are named by the Frencli anatomists Rainures. 
 8. A notch {incisura) is a cavity cut in the edge of a bone.* 
 
 The cavities wliich we have described exist only on one surface of a bone ; those which 
 perforate its substance are usually denominated foramina or holes. 
 
 1. When a foramen has an irregular, and, as it were, lacerated orifice, it is named a 
 foramen lacerum. 2. When its orifice is very small and irregular, it is called hiatus ; 
 when the opening is long, narrow, and resembling a crack or slit, it is denominated a 
 fissure ; as the sphenoidal fissure, the glenoid fissure, &c. 3. If the perforation runs 
 some way through the substance of a bone, it is called a conduit or canal ; as the Vidian 
 canal, carotid canal, &c. 
 
 There are some canals which lodge the vessels intended for the nourishment of the 
 bone : these are called nutritious canals. They are divided into three kinds. 
 
 The first, which belong exclusively to the shafts of long bones, and to some broad bones, 
 penetrate the substance of the bone very obUquely. These are the nutritious canals prop- 
 erly so called. Anatomists carefully point out their situation, size, and direction, in de- 
 scribing each bone. 
 
 The second kind are seen on the extremities of long bones, on the borders, or adjoin- 
 ing the borders, of broad bones. Cansds of this kind are generally near the articular sur- 
 faces. Their number is always considerable. Bichat has counted 140 on the lower end 
 of the thigh bone, twenty upon a vertebra, and fifty upon the os calcis. 
 
 The third kind of nutritious canals are exceedingly small, and might be denominated 
 the capillary canals of bones. They are found in great numbers on the surfaces of all 
 bones. They may be easily seen by the aid of a good magnifying glass ; their presence 
 is also indicated by the drops of blood which appear upon the surface of a bone on tear- 
 ing off the periosteum ; for example, on the internal surface of the cranium, after sep- 
 arating the dura mater. The diameter of these little canals has been calculated to be 
 about the l-20th of a line. 
 
 The farther progress of the above-mentioned canals is as follows : those of the first 
 kind, which belong to the long bones, soon divide into two secondary canals, one ascend- 
 ing, the other descending, and communicating with the central or medullary cavity. 
 Tliose which are situated in the broad bones form winding passages, which run for a 
 considerable distance in the substance of the bone. 
 
 The canals of the second kind sometimes pass completely through the bone (as in the 
 bodies of the vertebrae), and they communicate with the spongy tissue. The canals of 
 the third kind terminate at a greater or less depth, in the compact substance of the long 
 bones, and in the spongy tissue of the short bones. Such are the forms and general ar- 
 rangement of all the cavities which exist on the surface of the bone ; the following are 
 their uses : 1. They serve for the reception and protection of certain organs ; ex., the 
 occipital fossa;, which receive a portion of the cerebellum. 2. For insertion or surfaces 
 of attachment, as those on which muscular fibres are implanted, as the temporal and 
 pterygoid foss£e. 3. For the transmission of certain organs, such as vessels and nerves 
 which have to pass into or out of an osseous cavity ; such are the fissures, canals, fora- 
 mina, &.C. 4. For increasing the extent of surface ; as the sinuses and cells connected 
 with the organ of smelling, the surface of which they greatly enlarge by their numerous 
 anfractuosities.t 5. For the easy passage of tendons, and sometimes for their reflec- 
 tion, so that the original direction of the force is changed. To this class belong the bi- 
 cipital groove of the humerus, that for the tendon of the obturator intemus, &c. They 
 are generally converted into canals by means of fibrous tissue, which lines and com- 
 pletes them. 6. For the nutrition of bones, such being the use of the three orders of 
 nutritious canals already described. We must mention, along with these osseous cavi- 
 ties, other markings or impressions seen on the surface of many bones ; for example, 
 the shallow depressions in the lower jaw bone for the sub-lingual and sub-maxillary 
 glands, the impressions named digital on the internal surface of the cranium. 
 
 As the eminences of bones have been attributed to the mechanical effect of muscular 
 traction, so the various impressions and VEiscular furrows upon the internal surface of 
 the cranium have been considered to be the result of pressure and pulsation ; but it 
 would be more correct to limit ourselves to the simple statement, that the impressions 
 and eminences on the inside of the cranial bones exactly correspond with the elevations 
 and depressions on the surface of the brain, and also that the osseous furrows for the 
 middle meningeal artery correctly represent the ramifications of that vessel. 
 
 * [There is great latitude amo!ig anatomical writers in the use of these terms.] 
 
 t [Whatever other purpose tliey may serve, such cells and sinuses are, in most instances, to be regard- 
 ed as a provision for increasing the bulk and strength of bones without a corresponding augmentation ol 
 weight.T 
 
\ 
 
 12 OSTEOLOGY. 
 
 We may here point out certain rules to be followed in describing the external confor- 
 mation of bones. 1 . In describing the surface of a bone, it should be so divided that the 
 description may comprehend but few objects at a time. Thus, a broad bone is to be di- 
 vided into two surfaces, into angles and borders, which are to be successively studied. 
 2. The bone being thus subdivided into regions, each of these is then examined, care 
 being taken regularly to proceed from one part to its opposite, i. e., to pass from the su- 
 perior to the inferior surface, and from the anterior to the posterior. This is the only 
 method which, in a long description, will guard against omissions and avoid tiresome 
 repetitions. 3. It is also of great importance, in considering the objects presented by 
 each region or surface, to follow an invariable and regularly progressive order. Thus, 
 after exposing the objects placed in front, the examination should be continued uninter- 
 ruptedly from this point backward. 4. In the symmetrical bones, it is advisable to de- 
 scribe, first, the objects situated in the median line, and afterward those placed lateraDy. 
 
 Internal Conformation of Bones. — The tissue of bones, like that of most other organs, 
 presents the appearance of fibres, whose properties are throughout identical, but which, 
 by certain differences in their mode of arrangement, give rise to two forms or modifica- 
 tions of structure. To one of these the name of compact substance has been given ; to 
 the other, that of sjioncry or cancellated substance. A subordinate modification of the lat- 
 ter has long been described under the name of reticular tissue. 
 
 The spongy or cellular substance has the appearance of cells and areola?, of an irregu- 
 lar shape and variable size, all of which communicate with each other, and their walls 
 are partly fibrous, partly lamellar. The compact substance seems to consist of fibres 
 strongly compressed, so as to form a close, firm tissue. It is both fibrous and areolar. 
 By means of careful inspection, softening the bone in nitric acid, and studying its devel- 
 opment, it has been clearly proved that it is fibrous, and that in long bones the fibres are 
 arranged longitudinally, v.hile in broad bones they seem to diverge like rays from the 
 centre to every part of the circumference ; and that in the short bones they are disposed 
 irregularly, so as to form a superficial layer or crust. The researches of Malpighi have 
 conclusively shown that it is also areolar or spongy. By examining a bone softened by 
 nitric acid, or studying it in the fcetal state, it may be seen that, in fkct, the compact tis- 
 sue is nothing more than an areolar substance, the meshes of which are extremely close 
 and much elongated. Accidental ossifications, and the diseases of bone which so fre- 
 quently exhibit the compact tissue converted into spongy, and the spongy changed into 
 compact, complete the demonstration.* 
 
 In strictness, therefore, but one form of osseous tissue can be admitted, namely, the 
 areolar, which presents itself under two aspects, sometimes being close, compact, and 
 fasciculated ; sometimes spongy and cellular. Having thus become acquainted with these 
 two forms of osseous tissue, their general arrangement in the different kinds of bones is 
 next to be examined. 
 
 Internal Structure of Long Bones. — A vertical section of a long bone presents, in the 
 body or shaft, a cylindrical cavity, which, in the fresh state, is filled with a soft, fatty 
 substance, named the marrow. This cavity, or medullary canal, is of greatest diameter 
 at the middle of the shaft ; and, as it recedes from this point, it is narrowed and inter- 
 sected at various parts by lamellae detached from the sides, and forming a sort of incom- 
 plete partitions. Sometimes, however, there is a complete partition ; thus, I have seen 
 the cylinder of a femur divided into two distinct halves by a horizontal partition situa- 
 ted precisely in the middle of the bone. The medullary canal is not regularly cylindri- 
 cal, nor does it correspond in figure with the external surface of the bone. It commu- 
 nicates with the exterior by means of the nutritious canals, which sometimes run, for a 
 considerable distance in the substance of the bone, parallel to the medullary cavity, with 
 which they communicate by numerous apertures, and transmit the vessels as far as the 
 extremities of the bone. Some have supposed that the cavity existed only in order to 
 receive the man-ow, while, on the other hand, it has been maintained that the marrow 
 existed only to fill up the cavity. Whatever be the uses of the marrow, it is certain 
 that the existence of a cavity in the centre of long bones is an advantageous provision 
 for strength ; for it is proved in physics, that, of two cylinders, composed of the same 
 material in equal quantity, the one which is hollow, and whose diameters are, conse- 
 quently, greater, will offer greater resistance than that which is solid. By the contri 
 vance, therefore, of the medullary canal, there is an increase of strength without aug- 
 
 * [The description in the text applies to the more obvious structure of bone ; but, when examined with the 
 microscope, the osseous substance, both compact and spongy, is seen to consist of exceedingly fine lamell» 
 laid on one another. In the compact external crust of bones, these lamellae run parallel with the surface ; 
 they also surround, concentrically, the small cavities of the compact substance aad the cells of the spongy 
 texture, the parietes of which they form. They are not to be confounded with the coarser layers and plates 
 described in the compact substance by Gagliardi, Monro, and others of the older writers. Along with the la- 
 mellce there are minute, opaque, white bodies, with extremely fine lines irregularly branching out from thera. 
 These bodies, which can be seen only with the aid of the microscope, are named the osseous corpuscules ; 
 they obviously contain ralcareous matter, and are, probably, minute ramified cavities lined with earthy salts. 
 The earthy matter of bone, however, is not confined to the corpuscules, for the intermediate substance is 
 »lfx) impregnated with it. For a representation of the minute structure of bone, see Mullefs Physiology, 
 translated by Baly, pkte 1.] 
 
GENERAL OBSERVATIONS. 13 
 
 mentation of weight. There is another advantage in this arrangement, viz., the in- 
 crease of volume without corresponding increase of weight ; for, since the bones are 
 intended to give insertion to numerous muscles, it is necessary that their surfaces 
 should not be reduced to too small dimensions ; but this must have been the result had 
 the walls of the hollow cylinder been compressed so as to form a solid rod. The mar- 
 row consists of two distinct parts : 1. The medullary membrane, which lines the walls 
 of the canal. 2. The fatty tissue, properly so called, or the medullary hquid. 
 
 The membrane, highly vascular, serves to nourish the internal layers of the bone : it 
 possesses great sensibility and a high degree of vitality. The fatty tissue, on the con- 
 trary, is altogether insensible. If a probe be introduced into the centre of the meduUa 
 of a long bone in a living animal, no sign of pain is evinced so long as the instrument does 
 not touch the walls of the cavity ; but whenever the walls are rubbed or scratched, the pain 
 becomes excessive, and is manifested by piercing cries and violent struggles. 
 
 The proportion between the thickness of the walls of the cylinder and the diameter ot 
 the medullary canal varies not only in different individuals, but in the same person at dif- 
 ferent periods of life. In the aged, the thickness of the walls is proportionally much less 
 than in the adult : this is one cause of the great fragility of the bones in old age. Some- 
 times in the adult the walls are so thin, that the bone breaks by the slightest force : in 
 such cases, there is in some sort hypertrophy of the medulla and atrophy of the bone. 
 It is in such cases that fractures occur from the simple effect of muscular contraction, 
 or even from moving in bed. 
 
 It is in the central canal of long bones that those very deUcate osseous filaments are 
 observed, which, interlacing with each other, and forming large meshes, give rise to that 
 variety of spongy tissue wliich has received the name of reticular, and which appears in- 
 tended to give support to the medulla. The compact tissue diminishes, and the cells 
 increase in number, the greater the distance from the centre of the bone, so that the ex- 
 tremities are entirely composed of spongy substance covered by a thin layer of compact 
 tissue. It appears that the compact tissue which fonns the shafts of the bones divides 
 and subdivides into lamellae, in order to form the cells of the extremities. It is easy to 
 perceive the advantage of a spongy structure in the usually voluminous extremities of the 
 long bones : they could not have been compact without a great increase of weight, while 
 the additional strength thus acquired would have been redundant, and altogether useless. 
 
 The cells of the spongy substance are filled by an adipose tissue, similar to that which 
 exists in the bodies of long bones : from its greater fluidity, it has been denominated 
 meiullary juice. 
 
 Internal Structure of Broad Bones. — If the surface of a broad bone be scraped, or if the 
 bone be sawn across perpendicularly or obliquely, it will be found to consist of two lamellcB 
 or tables, separated by a greater or less thickness of spongy tissue. Hence the two plates 
 are insulated, and one may be fissured or broken without injury to the other. The thick- 
 ness of the compact laminae and of the spongy tissue is not uniform throughout the whole 
 extent of a broad bone. At the centre, for example, there is scarcely any spongy tissue, 
 and hence the transparency of the bone at this part. Towards the circumference, on 
 the contrary, the spongy tissue forms a very thick layer. 
 
 In the bones which form the vault of the cranium, the spongy substance takes the 
 name of diplo'e {6in?.6og, double), because it occupies the interval between the two tables. 
 
 From what has been said regarding the internal structure of broad bones, it is evident 
 that their distinctive character depends as much upon their internal as their external 
 conformation, and therefore the ribs, which, according to their external characters, seem 
 rather to belong to the long bones, have been classed among the broad, because they 
 exhibit in their internal structure the characters of the latter kind of bones. 
 
 Internal Structure of Short Bones. — The extremity of a long bone, if separated from the 
 shaft, would represent a short bone, both in its external and internal conformation ; for 
 a short bone is a spongy mass, covered by a thin layer of compact tissue. To their spongy 
 structure the short bones, as well as the extremities of the long, owe their specific lightness. 
 
 It should be observed, that what has been said concerning the internal structure of 
 bones applies, in strictness, only to those of the adult, because the younger the subject, the 
 less are the cells of the spongy tissue developed. And, in like manner, as the walls of the 
 cylinder of long bones diminish in thickness, and the medullary cavity increases in diam- 
 eter in the aged, so by the progress of age the walls of the cells become extremely thin, 
 and the cells themselves very large. In some cases of disease, for example, after white 
 swelling of the ankle-joint, I have observed true medullary canals in the cuboid bone 
 and calcaneum ; and I have remarked in one case of cancer of the breast, that the ribs 
 adjoining the tumour were hollowed out by a sort of medullary canal. It is to this dimi- 
 nution of the osseous substance, this kind of atrophy of the bone, that I am disposed to 
 attribute the fragility so often observed in the whole osseous system in cancerous diseases. 
 
 Chemical Composition of Bones. — The bony tissue consists essentially of two distinct 
 elements, one inorganic, the other organized. When a bone is subjected to the action 
 of dUute nitric acid, the salts are removed ; it becomes flexible and elastic like cartilage, 
 and though retaining its original bulk and form, it is found to have lost a great part of 
 
T^ OSTEOLOGY. 
 
 its weight. By this process its saline ingredients have been dissolved, and nothing re- 
 mains but its organic constituents, which, being subjected to boiling, present all the 
 characters of gelatine. 
 
 On the other hand, if a bone be calcined, the whole of its organic matter is destroyed, 
 giving out during the process the odour of burned horn. A substance remains which 
 preserves exactly the shape and size of the original bone, but at the same time is very 
 light, porous, and so friable that it crumbles to powder under the slightest pressure. If 
 the calcination be complete, the bone is rendered perfectly white, but it is black when 
 the burning has not been carried sufficiently far ; it m^y even be vitrified by a more in- 
 tense heat applied for a longer time. Prolonged exposure to the action of air and moist- 
 ure in like manner remove the organized substance, and leave only a calcareous residue. 
 The two elements of bone do not bear the same proportion at different ages. Certain 
 diseases greatly affect the predominance of one or the other, producing almost the ssune 
 effects as chemical agents. 
 
 To the inorganic matter the bones owe their hardness and durability ; to the organized 
 substance they are indebted for their vitality and the slight degree of flexibility and elas- 
 ticity which they possess. 
 
 The following are the results furnished by the cKemical analysis of M. Berzelius : 
 
 1. Okganized Part \ ^ Animal matter reduced to gelatine by boiling . 32-17 
 12. Insoluble animal matter rlS 
 
 {Phosphate of lime 51'04 
 Carbonate of lime ....... ll'SO 
 Fluate of lime 2'0 
 Phosphate of magnesia ri6 
 Soda and chloride of sodium 1"20 
 
 The bones are furnished with vessels : by one set arterial blood is transmitted, by 
 another venous blood is returned. 
 
 1. The arteries are of three orders, corresponding with the osseous canals, which have 
 been described in speaking of the cavities of bones. 
 
 First Order, or Arteries of the Medullary Canal of Long Bones. — In each medullary canal 
 there is at least one principal artery which enters by the nutritious canal and divides 
 almost immediately into two branches, one ascending, the other descending. These 
 subdivide into an infinite number of small branches, the interlacements of which form 
 that vascular network called the medullary membrane. With this network the vessels 
 of the second order freely anastomose after their entrance at the extremities of the bone. 
 In consequence of this important communication, the vessels, notwithstanding the great 
 difference in the manner of their entering the bone, can reciprocally supply each other 
 with blood. In illustration of this, Bichat relates a singular case, in which the nutritious 
 foramen of a tibia was completely obliterated, and yet the nutrition of the bone was un- 
 impaired. The medullary artery gives off the twigs for those layers of compact tissue 
 which form the parietes of the medullary cavity. 
 
 The arteries of the second order, destined for the spongy tissue, enter the bones by the 
 nutritious foramina of the second order ; but their number by no means corresponds with 
 that of the foramina, which are for the most part destined for the transmission of veins. 
 These arteries communicate hoth with the medullary artery already mentioned and vdth 
 the arteries of the periosteum. 
 
 The arteries of the third order, or the periosteal arteries, are exceedingly numerous. This 
 class comprehends the innumerable httle arteries which, after ramifying in the perioste- 
 um, enter the bone by the minute canals of the third order. These small vessels, spe- 
 cially distributed to the exterior layers of compact substance, anastomose with the two 
 preceding orders of vessels. 
 
 2. The veins of bones follow the course of the arteries. But there are peculiar venous 
 canals in the interior of the broad and the short bones, and in the spongy extremities of 
 the long bones. These canals were first described by M. Dupuytren in the cranial bones, 
 where they are very obvious : they are perforated with lateral openings, by which they 
 receive blood from the adjoining parts ; their parietes are formed by a very thin plate of 
 compact tissue, and they are lined by a prolongation of the internal membrane of the 
 veins. We shall afterward see that there is a complete analogy between these venous 
 canals and the sinuses of the dura mater, the only difference being in the nature of their 
 parietes, which are fibrous in the sinuses, but bony in the canals in question. I have 
 remarked, that in the foetus and new-bom infants, the cells of the spongy tissue, which 
 subsequently contain adipose matter, are filled with venous blood. 
 
 Lymphatic vessels have not yet been actually demonstrated in the bony tissue ; but it 
 is probable that they really exist there ; at least, the process of nutrition in bones, and 
 certain morbid phenomena which they present, lead to the beUef of their existence. 
 
 The cellular tissue also enters into the composition of the bones : it contributes to form 
 their fibrous structure. 
 
 Nerves can be demonstrated in connexion with most of the bones of the skeleton. 
 But it is necessary to distinguish those nerves which merely pass through the bones 
 from those which are distributed on their substance. 
 
DEVELOPMENT OF BONES. J|^ 
 
 Development of Bones, or Osteogeny. 
 
 From the time of their first appearance in the foetus, to the period of their complete 
 development, the bones pass through a series of changes, which constitute one of the 
 most important circumstances in their history. The investigation of these changes, or 
 of the successive periods of development, is the object o{ osteogeny. 
 
 The development of the bones, considered generally, presents three phases or periods, 
 designated by the name mucous, cartilaginous, and osseous stage. 
 
 1. The mucous stage. The mucous condition, the cellular of some authors, has not 
 been well defined. Some apply the term to that period of formation in which the bonea 
 and the other organs of the body form but one homogeneous mass of a mucous aspect 
 others use the term to signify a more advanced stage, in which the bones, acquiring a 
 greater consistence than the surrounding parts, begin to show their development through 
 these more transparent tissues. In the latter sense, the mucous stage is obviously no- 
 thing but the commencement of the cartilaginous, and therefore the first acceptation is 
 the only one to be retained. 
 
 2. The cartilaginous stage succeeds the mucous, though the time of the transition from 
 the one to the other has not been precisely ascertained. Several anatomists are of opin- 
 ion, with Mr. Howship, that the cartilaginous state does not necessarily intervene be- 
 tween the mucous and osseous conditions ; that its occurrence is only satisfactorily de- 
 monstrated in such bones as are late in ossifying, and that it constitutes a sort of provis- 
 ional condition, in which the cartilage is employed to perform the office of bone. Bui 
 when we take into consideration, in the first place, the rapid transition from the cartila- 
 ginous to the osseous stage in certain bones, and, secondly, the translucency of newly- 
 formed cartilage when of inconsiderable thickness, as in the cranium, where the carti- 
 lage is scarcely to be distinguished from the two membranes between which it is placed, 
 we can conceive that the cartilaginous stage may easily have been overlooked. On the 
 other hand, the constant result of my observations proves that, in the natural process of 
 ossification, every bone passes through the state of cartilage. 
 
 When the different pieces of the skeleton assume the cartilaginous condition, the 
 change occurs throughout their whole substance at once. The notion of central points 
 of cartilaginification, corresponding with the points of ossification, is purely hypotheti- 
 cal : a bone becomes cartilaginous in all parts simultaneously, and never by insulated 
 points. The cartilage has the same figure as the future bone. 
 
 Bones which are to be permanently united by intermediate cartilage, are formed from 
 m ;. imitive piece of cartilage, as those of the cranium and face : those, on the other 
 haau, which are connected together only by ligaments, are distinct and separable while 
 in the cartilaginous -state. 
 
 3. The osseous stage. The cartilaginous condition of the skeleton is completed by 
 the end of the second month ;* but ossification conunences in several places long before 
 this period. The first point of ossification appears after the fourth week in the clavicle ; 
 the second, in the lower jaw. From the thirty-fifth to the fortieth day points of ossifica- 
 tion appear sometimes successively, in other cases simultaneously, in the thigh-bone, 
 the humerus, the tibia, and upper jaw-bone. From the fortieth to the fifty-fifth day, 
 points of ossification appear at short intervals in the annular portion of the uppermost 
 vertebrse, in the bodies of the dorsal vertebrae, in the ribs, the tabular bones of the scull, 
 the fibula, the scapula, the ilium, the nasal, palatine, and metacarpal bones, the phalan- 
 ges of the fingers and toes, the metatarsus, &c. Once commenced, the ossification pro- 
 ceeds with more or less rapidity in the different bones during the remainder of intra- 
 uterine hfe. 
 
 In the child at birth, the shafts of the long, as well as the broad bones, are far advan- 
 ced in development. As to the short bones, the vertebrae are scarcely less early in their 
 evolution than the long and broad bones ; the calcaneum, cuboid, and sometimes the as- 
 tragalus, have points of ossification, but only commencing. The extremities of the long 
 bones, with a single exception, the lower end of the femur, are as yet without ossifying 
 points. The remaining short bones and extremities of long bones ossify subsequently. 
 Of the tarsal bones, the scaphoid is the last to ossify ; the pisiform is the latest among 
 the carpal bones ; the patella is ossified at the age of three years. 
 
 In regard to the process of ossification, a question of the highest interest presents it- 
 self, viz.. Is the successive appearance of the centres of ossification governed by any general law? 
 
 The order of commencement of the points of ossification is in no way dependant on 
 the size of the bones. It is true that the smaller bones, excepting the ossicles of the 
 ear, are later in appearing ; but, at the same time, it is not the largest bones that are the 
 earliest ; thus, the bones of the pelvis appear long after the clavicle. 
 
 * [The relative time of ossification of the different bones, or, at least, the order in which it commences in 
 them, is easily determined ; but owing to the uncertainty respecting the age of the embryo in its early stages, 
 the absolute time of foetal life at which each bone begins to ossify is very uncertain, and, accordingly, the 
 statements of many anatomists differ from that given in the text : thus the seventh week is assigned by some 
 as the period when ossification commences in the clavicle. The age fixed by the author appears too early.] 
 
16 OSTEOLOGY. 
 
 Proximity to the heart or great vessels has no effect on the precocity of development. 
 Though the ribs vt'hich are near the heart ossify speedily, the breast-bone, on the other 
 hand, which is still nearer, is one of the bones latest in ossifying. Again, the anterior 
 and inferior angle of the parietal, which is close to the anterior branch of the middle 
 meningeal artery, is the part of the bone which last ossifies. The femoral artery lies on 
 the confines of the os pubis and ilium, which at that part long remain cartilaginous. 
 
 The true law which governs the order of appearance of the points of ossification is 
 this, viz., that the period of formation is earlier or later in the several bones according 
 to the period at which they are required to fulfil their oflice in the economy. Thus, the 
 jaws being required to act immediately after birth, are ossified before the other bones of 
 the head. In the same way, the ribs, destined for a function which must commence 
 from the moment of birth, are for this purpose completely ossified : the vertebrae and 
 bones of the cranium appear early, because of their use as protecting the spinal cord and 
 brain ; and it is thus that the pretended correspondence between the rapidity of ossifica- 
 tion and proximity to the nervous centres is explained. 
 
 Although several of the bones are completed solely by an extension of the primitive 
 nuclei of ossification, the greater number acquire, in addition to these principal or es- 
 sential pieces, complementary points of ossification named epiphyses. Thus, while in 
 the frontal the two original points of ossification suffice by their extension for the- com- 
 pletion of the bone, the vertebrse, on the other hand, have three primary osseous nuclei, 
 one for the body, and two for the laminae and processes ; and five complementary pieces 
 of ossification, namely, two for the body, and one each for the tips of the spinous and 
 transverse processes. 
 
 The transition from the state of cartilage to bone is attended with the following phenom- 
 ena : the cartilage becomes more dense ; its colour is at first a dull white, but subse- 
 quently changes to deep yellow ; small irregular cavities are formed in its substance ; 
 red vessels show themselves ; a bony point appears in the midst of these vessels, and 
 this bony nucleus is spongy and penetrated with blood. The ossification spreads by lit- 
 tle and little, always preceded by a great development of vessels ; so that, in attentively 
 examining an ossifying cartilage, we find first an osseous point, then a red zone, next 
 an opaque layer of cartilage which is permeated by canals, and, lastly, the remaining car- 
 tilage traversed only by a few vascular canals which run towards the point of ossifica- 
 tion. Moreover, it is always at some aepth within the substance of the cartilage that 
 the first osseous points appear, and never at the surface. It is only in cases of accident- 
 al or diseased ossification, as in the cartilages of the ribs, that it occasionally begins at 
 the surface. It is unnecessary to pursue farther the immediate process of ossification • 
 nor need we here discuss the purely speculative question, whether the bone is really a 
 new part essentially distinct from the cartilage, which is absorbed and gives place to it, 
 or merely a deposite of earthy phosphate in a cartilaginous tissue. 
 
 In admitting that ossification is always preceded and accompanied by a great devel- 
 opment of vessels, a fact proved incontestably by Haller and Bichat, I must, neverthe- 
 less, decidedly dissent from the opinion that the appearance of blood in a cartilage is a 
 constant indication of approaching ossification; for several cartilages have naturally 
 bloodvessels, as may be seen in the cartilages of the ribs and larynx. 
 
 Tlie study of the development of the bones does not consist merely in determining the 
 number and time of appearance of their points of ossification : it comprehends, also, the 
 ulterior changes which take place in the osseous system, viz., the union of the primitive 
 points of ossification, and the appearance and junction of the complementary points of ossifica- 
 tion. It is to be remarked, that the order of development and union of the points of os- 
 sification does not always correspond with that in which they originally appear ; nay, it 
 is often the reverse. Thus, the lower epiphysis of the femur is the earliest in appearing, 
 and it is the last in joining ; while, on the other hand, the upper end of the radius is one 
 of the latest of the epiphyses in appearing, but is joined to the bone before all, or nearly 
 all, the rest. The junction of the pieces of ossification is not complete till about the age 
 of twenty-five years, at which time the lower epiphysis of the femur unites with the body 
 of the bone. 
 
 General Mode of Ossification of Eminences and Cavities. — M. Serres, in a very remarka- 
 ble work, has given, under the title of General Laws of Osteogeny, the results of his ob- 
 servations concerning the development of azygos or median bones, and of eminences 
 and cavities ; and with a rapid notice of these, we shall conclude what is to be said on 
 the points of ossification. 
 
 1. By the law of symmetry, which, according to M. Serres, governs the development 
 of all bones situated on the median line, every such bone is originally double, that is, 
 composed of two separate halves, which, advancing to meet each other, are at last join- 
 ed. Thus there are originally two osseous halves of the spinal column, and two demi- 
 sterna. The basilar portion of the occipital, the body of the sphenoid, the cribriform 
 plate of the ethmoid, the vomer, and the spinous processes of the vertebrae, have, ac- 
 cording to this view, originally been double. But this law has many exceptions. Thus, 
 although some of the pieces of the sternum are conunonly formed from two lateral 
 
DEVELOPMENT OF BONES. iT 
 
 points, the first and the last are always, or almost always, developed from a single point 
 in their middle. The bodies of the vertebrae are most commonly formed from a single 
 primitive nucleus : the same is the case with the basilar portion of the occipital, the per- 
 pendicular plate of the ethmoid, the vomer, and the spinous processes of the vertebrae. 
 Instances of incomplete division of bones on the median Une must not be adduced in 
 proof of the existence of two primitive points of ossification. 
 
 2. Every eminence, according to M. Serres, is developed by a special point of ossifi- 
 cation. This is true generally : but how many eminences are formed merely by the ex- 
 tension of ossification from the piece which supports them ! Where, it may be asked, is 
 the special point of ossification for the articular processes of the vertebrae, the coronoid 
 process of the ulna, the external and internal protuberances of the occipital, &c. 1 There 
 are even double eminences developed from a single point, £is the condyles of the femur. 
 
 SPEvery cavity is formed by the union of at least two pieces of ossification ; so that, 
 when a bone furnished with a cavity consists of several pieces, the place of junction of 
 these pieces is at the cavity. Thus, the three pieces of the os innominatum meet together 
 at the cotyloid cavity. The same law, according to M. Serres, regulates the formation 
 of the foramina and osseous canals of every kind, as the medullary cavity of the long 
 bones, all the canals for vessels and nerves, as the carotid, vidian, &c. : according to 
 the same law, all the foramina in the bones of the scuU are formed originally of two 
 halves. But the facts are opposed to this doctrine when applied so universally. 
 
 Progress of Ossification in the three Kinds of Bones. — 1. In the loTig hones. Ossifica- 
 tion commences in their middle part. A small cylinder of bone appears, narrow in the 
 middle, expanded at the ends, tubular within, perforated already with the nutritious fo- 
 ramen, which is very obvious, and receives very large vessels. This Uttle cylinder grows 
 gradually thicker and longer, extending towards the extremities of the bone, which it 
 reaches about the time of birth ; while at this period the ossification is so far advanced 
 in the body of the long bones, their extremities are not yet osseous. It is only at later 
 periods, varying in different bones, that an osseous nucleus appears in the cartilaginous 
 extremities, increasing and encroaching upon the portion of cartilage which separates it 
 from the bony shaft, until that cartilaginous partition, gradually becoming thinner, is at 
 last itself invaded by the ossification. All the long bones have two essential or princi- 
 pal epiphyses, to which complementary epiphyses are sometimes added. The phalan- 
 ges* are an exception ; they have only one. It is this process which is named junction 
 of the epiphyses. The time of its completion is not confined to any very definite limits, 
 but it is over by twenty or twenty-five years. 
 
 Throughout the whole time of development the growth in length takes place, chiefly 
 by ossification of the intermediate cartilage, which separates the epiphyses from the 
 shaft, but partly, also, by longitudinal expansion of the ossified shaft itself The former 
 mode of increase has been satisfactorily established by Hunter ; the latter is proved by 
 the following experiment of Duhamel : Three needles being fixed in the shaft of a long 
 bone of a bird, at measured distances, it is found that after a certain time they become 
 farther separated, which proves that the osseous cylinder has undergone an elongation. 
 
 2. In the broad bones. 1. Among the broad bones, those which are symmetrical often 
 conmience by two points placed one on each side of the median line. 2. The asymmet- 
 rical bones are developed sometimes from a single point of ossification, as the parietal ; 
 sometimes by several, as the temporal. 
 
 One of the most remarkable circumstances in the development of broad bones is the 
 sort of radiation by which the deposition of calcareous phosphate extends, which spreads 
 from the centre where the first osseous point was deposited, and advances by divergent 
 rays to all points of the circumference, forming bony striae separated by intervals, which 
 are soon filled up by new osseous rays. As these rays are of unequal length, and are 
 separated at the circumference by intervals of greater or less extent, it follows that a 
 broad bone in the process of ossification must have at its circumference a scalloped or 
 jagged border, like the toothed edge of a comb. It is this form of ossification which 
 gives rise to the serratures of the sutures. 
 
 The broad bones are proportionally much thinner in the early periods of ossification 
 than subsequently, because at first the spongy texture is scarcely developed. At the 
 time of birth, the primary pieces of ossification not having united except in very few 
 places, and the ossification which spreads from the centre of the bones not having yet 
 reached the limits of their circumference, it follows that the constituent parts of bones, 
 and the edges of different bones which are destined in the end to meet together, are at 
 this period separated by cartilaginous, and, in some measure, membranous intervals, 
 which in the cranium constitute the fontanelles. After birth, ossification spreads more 
 and more in the broad bones ; at the same time they increase in hardness and thickness, 
 appearing as if to separate into two plates or tables, the interval between which be- 
 comes filled with spongy tissue. 
 
 The epiphysary or complementary points of ossification of some of the broad bones 
 
 * [Also the clavicle, the metatarsal, and usually the metacarpal bones.] 
 
 c 
 
1 8 OSTEOLOGY. 
 
 represent, in a certain degree, the epiphyses of the long bones. They occupy the cu- 
 cumference, and are thence named marginal epiphyses. Thus, in the cartilaginous bor- 
 der of the haunch-bone, which represents the crest of the ilium, a point of ossification 
 commences, and extending along its whole length, forms a marginal epiphysis, which 
 subsequently joins the rest of the bone, and in this respect is perfectly analogous to the 
 epiphyses at the extremities of the long bones. The epiphyses, then, are not an exclu- 
 sive attribute of the long bones, as Bichat maintained. They are found, also, in some of 
 the short bones. But it would be indulging in a false analogy to class the Wormian 
 bones, formed during the development of the cranium, with the epiphyses of the long 
 and the broad bones ; for they have peculiarities which are never found in true epiphy- 
 ses. Thus, 1. They are not joined by osseous union, as is the case with epiphyses, but 
 always by suture. 2. There is no constancy in their time of appearance, nor in ^eir 
 figure, which is irregular, nor in their size, which is, in general, greater the earlierlftey 
 have appeared, because they have then had longer time to extend themselves before 
 meeting the neighbouring bones. 
 
 From what has been said, we conclude that the broad bones have a twofold mode of 
 mcrease in breadth, namely, the successive addition of bony substance to their borders, 
 and the formation of marginal epiphyses. In every broad bone which is formed from 
 several pieces, and which has on its surface a part for articulation, this last becomes 
 the centre in which the different pieces meet, and are ultimately joined when the ossi 
 fication is completed. 
 
 3. In the short bones. These are the latest in being ossified ; a great number of them 
 are still cartilaginous at birth. The short bones are not destitute of epiphyses, as is 
 proved by the ossification of the vertebrae and calcaneum. Their ossification, in fine, 
 presents the same phases, and follows the same progress, as that of the extremities of 
 the long bones, which they resemble in so many respects. 
 
 Changes which take place in Bones after Maturity. 
 
 To obtain a complete notion of the development of the bones, we must not rest satis- 
 fied with ascertaining the number of points of ossification, their successive appearance, 
 and their mode of junction ; we must also study the changes which they undergo after 
 they have attained their full growth. 
 
 The increase of the bones in height teraiinates when their several pieces have become 
 united : the time when this is accomplished varies from the age of twenty to thirty 
 years ; but they continue to increase in thickness for a considerable time longer. In 
 proof of this, we need only compare the bones of a young man with those of an adult of 
 forty. In old age the bones still undergo important changes : the medullary canal of the 
 long bones augments in width, and the tliickness of its parietes diminishes in proportion ; 
 and something similar takes place in the broad and the short bones. 
 
 Another important fact to be here mentioned is, that the relative proportion of calca- 
 reous phosphate and animal matter undergoes continual changes in the course of life. 
 Thus, by an analysis of Dr. I. Davy, it was shown that the proportion of calcareious phos- 
 phate was a fifth less in a child of fifteen years than in the adult. The same chemist 
 found that the proportion of phosphate of lime in an adult occipital was to that in an 
 occipital bone of an aged person as sixty-four to sixty-nine. 
 
 JSTutrition of Bones. 
 
 The fact of the nutrition of bones, and the process of composition and decomposition 
 in which it consists, appear to me to be demonstrated by the experiment with madder. 
 If an animal is fed for some time with food impregnated with thfe juice of madder, its 
 bones soon become coloured red, as may be ascertained by ampirfttfang a limb ; but, by 
 suspending the use of that substance for some time, the bones recover their natural col- 
 our. In this experiment, there is no doubt that the calcareous phosphate is the vehicle 
 of the colouring matter, for the bones are the only parts that become coloured ; aU that 
 is cartilaginous remains free from colour. We may infer from this that a twofold move- 
 ment continually goes on in bones, by which new molecules are first deposited and then 
 removed, after they have for a longer or shorter period formed part of these organs.* 
 
 The administration of madder, moreover, demonstrates a fact, which was proved by 
 Duhamel du Monceau in a very curious set of experiments, namely, that the growth of 
 bones takes place by the successive deposition of new layers, formed by the undermost 
 or contiguous layers of the periosteum. Thus, let a pigeon be fed with food impregnated 
 with madder, suspend the use of the madder for a time, then renew it ; after this, the 
 bones, when cut through, exhibit a red layer next their surface, then a white layer, then 
 a red layer again. 
 
 Thus the bones grow in two ways, namely, by the interstitial mode of groAvth, or by 
 intussusception, which they have in common with the other tissues ; and, secondly, by 
 juxtaposition. 
 
 * A somewhat subtle objection would be the following : May not the colouring matter be deposited and 
 again carried off without the particles of phosphate of lime being necessarily subject to the same vicissitudes ! 
 
THE VERTEBRAL COLUMN. 
 
 19 
 
 THE VERTEBRAL COLUMN. 
 
 Gene-al Characters of the Vertehra. — Characters peculiar to the Vertehra of each Region. 
 — Characters proper to certain Vertcbree. — Vertebrae of the Sacro-Coccygeal Regvm. — Tht 
 Vertebral Column in general. — Development. 
 
 The vertebral column (from the Latin word vertere, to turn, because ^' *• 
 
 the body turns round this as an axis), spine, or rachis, is that long, flex- c _; <i 
 ible, hollow, bony stem, the principal lever of the body, which affords 
 support to almost the entire skeleton, and, at the same time, shields 
 and protects the spinal marrow. It is situated at the posterior and 
 median portion of the trunk, extending from the cranium to the pelvis, 
 where it terminates in two osseous pieces, tiie sacrum and coccyx, 
 which may, in fact, be regarded as a continuation of the column. The 
 sacrum and the coccyx have been separated from the vertebral column 
 merely on account of the osseous junction of the vertebrae of which 
 they are composed.* It is articulated with the base of the cranium 
 at the part where the posterior joins the two anterior thirds of this 
 cavity : it corresponds with the posterior portion of the pelvis, an ar- 
 rangement most favorable for maintaining the erect position. 
 
 The vertebral column is situated behind the alimentary canal in 
 man, above it in the lower animals. In front are suspended the or- 
 gans of respiration and circulation, to which it affords protection, and 
 which constantly tend to incline it forward : to its sides are attached 
 the ribs and the extremities, the thoracic having an indirect and 
 movable, the abdominal a fixed connexion. 
 
 From the limits here assigned to the vertebral column, it follows 
 that this part of the skeleton extends the whole length of the trunk, 
 forming the entire osseous support of the neck and loins, the poste- 
 rior column of the thorax, and even the posterior wall of the pelvis. 
 Hence it is divided into four regions, viz., a cervical, a dorsd or tho- 
 racic, an abdominal, and a pelvic or sacro-coccygeal region. 
 
 The vertebral column (fig. 1) is composed of twenty-six bones 
 piled above each other : the last two have received the names of 
 sacrum and coccyx, and the others, which constitute the vertebred col-- 
 umn, properly so called (a d), are denominated vertebra : they have 
 also been called true vertcbree, as distinguished from the false vertc- 
 bree, which, by their osseous union, form the sacrum {d e) and coccyx 
 (c/). The sacrum is composed of five of these false vertebrae, and 
 the coccyx of four, in a rudimentary state. The description of these 
 latter bones will be deferred, in the mean time. The first seven true 
 vertebrae form the cervical region (a b) ; the twelve which succeed 
 constitute the dorsal {b c) ; and the last five the lumbar region (c d). 
 
 There are occasionally, but very rarely, some variations in the 
 number of vertebrae. In a few cases only six cervical vertebrae have 
 been found ; and Morgagni, who first observed this anomaly, consid- 
 ers it to be a predisposing cause of apoplexy, on account of the ac- 
 companying shortness of the neck, and consequent approximation 
 of the heart and brain. There are sometimes thirteen dorsal ver- 
 tebrae : sometimes the fifth lumbar is united to the first sacral, and 
 there are then only four lumbar vertebra?. In other cases, the first 
 sacral vertebra is distinct from the rest, and the lumbar portion of the 
 column then consists of six. 
 
 The vertebrae present general characters, which distinguish them / 1^'*^ 
 from all other bones : they have also characters peculiar to each particular region ; and 
 in each group or region certain vertebrae have individual distinctive characters. 
 
 General Characters of the Vertcbree. 
 Every vertebra {figs. 2, 3, 4, 5, 6, 7) is essentially asymmet- 
 rical ring, a segment of the cylinder which protects the spinal 
 marrow, and is, consequently, perforated by a foramen, denom- 
 inated the vertebral or rachidian foramen {I, fig. 2). As it con- 
 curs also to form part of a supporting column, it presents a kind 
 of enlargement or solid cylinder, of which the posterior fifth 
 has been removed. I'his enlargement is the body of the ver- 
 tebra (2). Each vertebra gives attachment to numerous mus- 
 cles, by very marked eminences for insertion — the spinous (3) 
 and transverse processes (4 4). It is articulated with the other 
 
 * The same is true of anchylosis, as of certain differences of form and development, viz., that ihev lead t* 
 die establishment of varieties, but cannot form the ground of total separation. 
 
 Fig. 2. 
 
20 
 
 OSTEOLOGY. 
 
 vertebrae by four articular processes (5 5), two superior and two injeriar. Lastly, it pre- 
 sents two superior and two inferior notches {7, Jigs. 4, 5), which unite to form the inter- 
 vertebral foramiTia, through which the vessels and nerves are transmitted. 
 
 Fig. 3. A. The body of the vertebra (2) occupies the anterior portion of 
 
 / ,^, 5 the vertebral ring, and presents /owr surfaces. The superior and 
 
 "* ■'"' inferior surfaces are connected with the contiguous vertebra, and 
 
 are slightly hollowed for the reception of the intervertebral sub- 
 stance. This double excavation is the vestige of the deep bicon- 
 ical cavity, so remarkable in the vertebrae of fishes. The ante- 
 rior surface is convex transversely, and presents a horizontal 
 ^"*' groove (2, Jigs. 4 and 5), which is deeper laterally than in the me- 
 dian line, and in cases of abnormal curvature is greater on one side than on the other. This 
 groove is the rudiment of that circular constriction which exists in the vertebrae of reptUes 
 and fishes, and in the cervical vertebrae of birds : it has the double advantage of economy, 
 both as to the weight and the bulk of the bone. The posterior surface is concave, and 
 forms part of the vertebral canal. It is pierced by numerous foramina of considerable size, 
 which are the orifices of venous canals hollowed out in the substance of the vertebra. 
 Smaller foramina of the same nature exist also on the anterior surface. 
 
 B. The vertebral foramen {I, fig. 2) exhibits certain variations in form and dimensions 
 in the different regions of the spine ; but in nearly all the vertebrae it approaches more 
 or less to the triangular form. The differences which it presents in the extent of its 
 diameters bear reference partly to the size of the spinal marrow, and partly to the ex- 
 tent of motion in each region. 
 
 C. The spinous process {3, figs. 2, 3, 4, 5) is that eminence of considerable size which 
 arises in form of a spine from the posterior part of the vertebral arch. It forms a lever 
 for the extensor muscles of the trunk, and accordingly varies in length, shape, and di- 
 rection, in the different regions. It bifurcates, as it were, at its base, and passes into the 
 two lamina (6 b, fig. 2), which constitute the lateral and posterior portions of the arch. 
 
 D. The articular processes (5 5) arise from the lateral portions of the arch near its junc- 
 tion with the body of the vertebra : their direction is in general vertical, i. e., perpendicu- 
 lar to the direction of the articulating surfaces of the body, which are horizontal. They 
 are four in number, two superior or ascending, and two inferior or descending ; they are 
 placed symmetrically on each side of the median line, and are covered with cartilage in 
 the fresh state, to form a movable joint with the articular processes of the adjacent 
 vertebrae ; they project beyond the level of the bodies of the vertebrae, so that their artic- 
 ulations correspond with the intervertebrtd substances. Hence the vertebral column 
 presents two successive series of articulations : one constituted in front, by the union of 
 the bodies ; the other behind, by the articular processes. 
 
 E. The transverse processes (4 4) are lateral prolongations, which arise from each side 
 of the vertebral ring, pass horizontally outward, and vary in length and size in the dif- 
 ferent regions. 
 
 F. In front of the articular and transverse processes, immediately behind and at the 
 side of the body of the vertebra, are four notches cut in the lateral parts of the ring (7, 
 figs. 4 and 5) : the inferior are generally deeper than the superior, but their depth varies 
 considerably in the different regions. The part of the vertebral ring between the upper 
 and lower notches is reduced to a sort of pedicle ; it is the weakest part of the vertebra, 
 and, consequently, it is the principal seat of torsion in curvatures of the spine. The con- 
 stituent parts of a vertebra are, therefore, 1. In the median line, the body, the foramen, the 
 spinous process, and the lamina ; 2. On each side, the articular and transverse processes, the 
 notch, and the pedicle. 
 
 Characters peculiar to the Vertebra of each Region. 
 
 ^^s- 4. The characters distinctive of the vertebrae of each region 
 
 of the spine are most marked in those placed in the middle 
 of the respective region, for at its extremes the vertebrae 
 acquire intermediate or mixed characters belonging to the 
 two regions near the confines of which they are situated. It 
 may be remarked, that the vertebrae of each region may be 
 at once recognised by Fig. 5. 
 
 one single distinctive 
 character : thus, the cer- 
 vical vertebrae are al- 
 ways known by a fora- 
 men in the base of the 
 transverse processes (a, 
 fig. 2) ; the dorsal vertebrae by facettes hollowed out 
 on the sides of the bodies (6 6, fig. 4) ; and the lum- 
 bar {fig 5) by the absence of the two preceding 
 •Tnarks." The characters just mentioned might, then, suffice as mere distinctive marks, bu* 
 
THE VERTEBRAL, COLUMN. 
 
 M 
 
 they woiild not answer the purposes of exact anatomical description. Indeed, a vertebra 
 is cervical, dorsal, or lumbar, rather in virtue of its entire form and structure than by 
 reason of any single circumstance pertaining to it. 
 
 We shaU examine in regular order each part of a vertebra, as it exists in the different 
 regions. 
 
 Bodies of the Vertebrae in different Regions. \: 
 
 The first distinctive character is their size. This progressively increases from the cer- 
 vical to the lumbar region (a, 6, c, d,fig. 1) : taking the size of the bodies of the lumbiir 
 vertebrae as unity, that of the dorsal would be two thirds, and that of the cervical one half 
 
 The second distinctive character is the proportion of the diameters. In all vertebrae the 
 transverse diameter is the greatest, and the vertical the smallest. In the lumbar verte- 
 brae the height or vertical diameter is twelve lines (one inch), in the dorsal nine lines 
 (three quarters of-^ inch), and in the cervical six lines (half an inch). In the cervical 
 and lumbar regions, the vertical diameter of the body is less behind than before, which 
 inequality gives rise to the anterior convexity of these regions. In the dorsal region, on 
 the other hand, the vertical diameter is shortest anteriorly. In the lumbar region, the 
 transverse diameter does not exceed the vertical and the antero-posterior by more than 
 one third at most. In the dorsal region no one diameter is strikingly predominant ; but 
 in the cervical the transverse is almost double that of the antero-posterior and the ver- 
 tical diameters. 
 
 The third distinctive character is formed by the lateral ridges of the bodies of the cervi- 
 cal vertebra. From the two sides of tlip superior surface of the bodies of the cervical 
 vertebrae arise two small ridges {fig. 2, on each side of 2), which are received into 
 corresponding depressions on the inferior surface of the vertebra above. This mutual 
 fitting-in of the bodies of the cervical vertebrae compensates for the less secure connex- 
 ion of their articular processes, and which insecurity is, moreover, of less importance, 
 from the bodies being united by disks of intervertebral substance. 
 
 The fourth distinctive character consists in the two demi-facettes on each side of the 
 bodies of the dorsal vertebra. (6 6, fig. 4). These demi-facettes, when united with the cor- 
 responding parts of the neighbouring vertebrae, form angular excavations, in which the 
 posterior extremities of the ribs are received. This character belongs exclusively to the 
 dorsal vertebrae. 
 
 The fifth distinctive character is the excavation of the superior and inferior surfaces of 
 the bodies, which is less in the dorsal region than in the cervical or lumbar. From this dis- 
 position it results, that a lenticular space of a much greater size intervenes between 
 every two of the lumbar and cervical vertebrae than between the dorsal : the mobility is 
 consequently much increased, from the greater size of the intervertebral substance. 
 
 The specific characters, then, of the bodies of the vertebrae in the different regions are 
 the following : 1. Lateral ridges on the superior surface of the cervical vertebra. 2. Lateral 
 facettes on the dorsal vertebra. 3. TTie absence of these two characters, and the preponder- 
 ance of size in the lumbar vertebra. If the body of a vertebra be presented for our inspec- 
 tion, we can at once determine from these characters the region to which it belongs. 
 
 The Vertebral Foramen and the Jfotches in the different Regions of the Spine. 
 
 The vertebral foramen and the notches present certain marked distinctions in the ver- 
 tebrae of the three regions, by which they may be recognised by a practised eye. 
 
 1. In the cervical region, the transverse diameter of the foramen {I, fig. 2) considera 
 bly exceeds the antero-posterior. 2. In the dorsal region, the two diameters are almost 
 equal, but there is this much which is remarkable, that a very considerable depression 
 exists on the posterior surface of the body of the bone. 3. In the lumbar region, the 
 transverse diameter is the greater, but the difference is much less remarkable than in the 
 cervical. The following is a comparative table of the diameters in the three regions • 
 Transverse diameter. Antero-posterior diameter. 
 
 In the neck, 6 lines 
 back, 6 lines, 
 loins, 8 lines. 
 
 In the neck, 1 1 lines, 
 back, 7 lines, 
 loins, 10 lines. 
 
 It may be remarked here, that these differences correspond with the extent of motion 
 in each region. In the lumbar region, which is more movable than the dorsal, the fora- 
 men is larger ; and in the cervical region, where the lateral motions are more extended 
 than in the loins, the transverse diameter is still greater, in the proportion of eleven to 
 ten. It must be observed, however, that the diameters of the foramen bear reference 
 not only to the mobility of the part, but also to the size of the spinal marrow. 
 
 The notches present also certain differences in the different regions ; thus, in the dor- 
 sal and lumbar regions (7,figs. 4 and 5), the inferior are much deeper than the superior ; 
 in the cervical region they are of almost equal depth {fig. 3). It may also be remarked, 
 that the depth of the notches, and, consequently, the size of the intervertebral foramina. 
 
82 OSTEOLOGY. 
 
 are generally proportional, not only to the size of the spinal ganglions, but also to tlie 
 capacity of the venous canals, which establish a communication between the external 
 and internal veins of the spine. It is then possible, when only the vertebral foramen 
 and the notches are seen, to determine the region to which the bone belongs. 
 
 The Spinous Processes and Lamincs in the different Regions. 
 
 1. In the cervical region, the spinous processes are prismatic and triangular {3, figs. 2, 
 3), grooved inferiorly for the reception of the spinous process of the vertebra below du- 
 ring the movements of extension, and bifurcated at their summit, for the purpose of 
 muscular insertion. Their direction is horizontal, and, consequently, favourable to 
 extension. 
 
 2. In the dorsal region (3, fig. 4) they are prismatic and triangular, with a tubercle at 
 their summit ; their direction is extremely obhque, approaching to the vertical. This 
 direction, together with their great length, causes them to descen^tfonsiderably below 
 the inferior surface of the body of the vertebra. Hence a sort of injBncation, and to such 
 a degree that a very slight movement of extension causes them to touch each other. 
 
 3. In the lumbar region the spinous processes (3, fig. 5) are broad, thick, and quadrilat- 
 eral, presenting on their sides a large surface for muscular insertion ; their posterior 
 border is thick, tuberculated, and triangular. Their direction, being horizontal, presents 
 no obstacle to extension. 
 
 The two laminae {b b, fig. 2), which form the posterior arch of the vertebra, are con- 
 tinuous with the base of the spinous process. Their length is directly proportionate to 
 the dimensions of the part of the canal to which they correspond, and their thickness is 
 in proportion to the size of the spinous process'. 
 
 1. In the cervical region the laminae are thin, very long, and so inclined that when the 
 head is erect, i. e., in a position intermediate between flexion and extension, the inferior 
 edge of the superior laminae passes beyond the superior border of the vertebra below, so 
 that there is a true imbrication of these laminae, not less marked than that which we 
 have observed of the spinous processes in the dorsal region. There has been, conse- 
 quently, no case recorded of the entrance of any penetrating instrument into the spinal 
 canal, in the situation of the undermost five cervical vertebrae ; which fact is the more 
 easily conceivable when we reflect that the least impression upon the back of the neck 
 excites, instinctively, an extension of the head, and thus increases the imbrication of 
 the laminae. 2. In the dorsal region the thickness of the laminae is greater than in the 
 neck, but still inferior to that in the loins ; they are comparatively much shorter than in 
 the cervical region, and, instead of forming an elongated rectangle, they represent a 
 square — nay, their vertical dimension almost exceeds the transverse. 3. In the lumbar 
 region they are characterized by great thickness, by diminution of the transverse, and 
 marked increase of tlie vertical diameter. In general, it may be stated that the height 
 of the lamina corresponds with the thickness of the body of the vertebra to which it be- 
 longs ; hence they are so narrow in the cervical region. 
 
 To sum up, then, the characters of the spinous processes and the laminae : 
 
 1. Cervical Region. — Processes prismatic and triangular, grooved inferiorly, bifurcated 
 with two tubercles at their summit, horizontal, short, and continuous, with long, narrow, and 
 thin lamina,, inclined so as to become imbricated. 2. Dorsal Region. — Spinous processes 
 prismatic and triangular, long, oblique, and tuberculated at their summit, with short vertical 
 laminae. 3. Lumbar Region. — Spinous processes quadrilateral, strong, and horizontal, with 
 very sJiort, thick, and vertical lamina. It is possible, then, from the spinous process and 
 its laminae alone, to determine the region of any vertebra. 
 
 The Articular Processes in the different Regions. 
 
 In the cervical region (5 5, figs. 2 and 3) the articular processes form small columns, 
 and are so directed that their articular siu'face makes, with the horizon, an angle of 
 about 45° ; the superior look upward and backward, the inferior downward and forward. 
 It is important to remark this direction, because it permits the movements of flexion, 
 extension, and lateral inclination : it is owing to the same circumstance, also, that lux- 
 ations of the cervical vertebrae may occur without fracture of their articular processes. 
 It should be also observed that the articular surfaces of the right and left sides are in 
 the same plane. 
 
 2. In the dorsal region (5 5, fig. 4) the articular processes are simple laminae, the di 
 rection of which is vertical and the surface plane. The superior look backward and out- 
 ward, the inferior forward and inward. The articular facette of the right side is not on 
 the same plane as that of the left. 
 
 I should observe that, in certain cases, the dorsal articular processes are found, as it 
 were, locked together, the extremity of the superior process being received into a deep 
 notch on the surface of the inferior process of the vertebra above. 
 
 3. In the lumbar region (5 5, fig. 5) the articular processes are very strong, with curved 
 
THE VERTEBRAL COLUMN. 23 
 
 surfaces. The superior concave look backward and inward, the inferior convex forward 
 and outward. They both represent two segments of a cyhnder, one of which complete- 
 ly surrounds the other, or, rather, the inferior resemble half hinges, which are received 
 into the half rings formed by the superior processes. It should be observed here, that 
 the superior articular processes are prolonged by certain tubercles, to which the name 
 of ajpophysary may be correctly appUed, and which serve for the insertion of muscles. 
 To sum up, then, what has been said : The cervical articular processes are small columns, 
 cut with plane faces, at an inclijiation of 45°, those of both sides on the same plane ; the dor- 
 sal are thin lamina, plane and vertical, but not in the same plane ; the lunibar strong, vertical, 
 and tuicrculated lamincz, with a curved articular surface. The region of any given verte- 
 bra may be easily recognised from its articular processes alone. 
 
 The Transverse Processes in the different Regions of the Spine. 
 
 No part of the vertebrae presents more decided variations in the different regions than 
 the transverse processes. 
 
 1. In the cervical region (4 i,Jigs. 2 and 3) they are grooved superiorly for the lodg- 
 ment of the anterior branches of the cervical nerves ; their base is perforated {a, fig. 2) 
 for the passage of the vertebral artery ; they have two borders, an anterior and posterior, 
 to which the inter-transversal muscles are attached ; their free extremity is bifurcated 
 for the attachment of muscles. It should be added, that these transverse processes, be- 
 ing on the same plane with the bodies of the vertebrae, double their transverse diameter 
 in front, and enable them to afford support to a great number of parts. 
 
 2. In the dorsal region (4, fig. 4) they are large and horizontal, much stronger than in 
 the other regions, and twice or three times the size of the spinous processes ; they are 
 much incUned backward, and the anterior surface of their extremity has a depression 
 for articulation with the tubercle of the ribs. Some anatomists have attached great im- 
 portance to the direction of the articular facettes, making it the basis of their notions of 
 the mechanism of respiration. The important modifications which the transverse pro- 
 cesses of the dorsal vertebrae present are evidently connected vdth the nature of their 
 functions, which are not only that of affording points of insertion to muscles, but also of 
 supporting the ribs with which they are articulated. 
 
 3. In the lumbar region, the transverse processes (4, fig. 5) are thin, narrow laminae, 
 flattened from before backward. They are situated in a plane anterior to that which the 
 transverse processes of the dorsal vertebrae occupy, and almost correspond with that of 
 the ribs, with which, also, they have numerous other analogies : hence the name costi- 
 form processes given them by some anatomists.* The characteristics, then, of the three 
 kinds of transverse process are, in the cervical region, a grooved projection with a foramen 
 at the base ; in the dorsal region, a strong process inclined backward, tuberculated, and artic- 
 ular at the extremity ; in the lumbar region, a small, thin, blunted projection. It is, therefore, 
 extremely easy to determine the situation of a vertebra by the transverse process. 
 
 The truth of what we formerly remarked will be now evident, viz., that a vertebra is 
 distinguished as cervical, dorsal, or lumbar, by the form of all its constituent parts. Uni- 
 form in their fundamental type, these bones present, in each region, and in each part, 
 certain differences adapted to their respective uses. 
 
 Characters proper to certain Vertebras. 
 
 We have now noticed, 1 . The general characteristics of the vertebrae, by means of 
 which they may be recognised from all other bones ; 2. The peculiar distinguishing 
 chraracters of the vertebrae in each region. We have now to examine in each region 
 those vertebrae which are distinct from all the others of that part of the spine. The 
 place of each vertebra might, strictly speaking, be determined by comparing it with all 
 the other vertebrae of the same region : in this way, those who are accustomed to artic- 
 ulate skeletons acquire surprising readiness. But a few vertebrae only possess suffi- 
 ciently characteristic peculiarities to determine their situations without comparison with 
 the others. It is only in the vertebrae at the extremity of each region, and which, on 
 account of their position, have a mixed character, that such distinctive'and individual 
 attributes can be observed. 
 
 The first, second, and seventh cervical vertebrae, the first, eleventh, and twelfth dor- 
 sal, and the fifth lumbar, require special description. 
 
 First Cervical Vertebra, or Atlas (jig. 6). 
 In the first vertebra, or atlas, the place of the body is supplied by an arch (a g), flattened 
 
 * The description which we have given of the transverse processes is in accordance with that usually foniLd 
 m works on human anatomy. Several modern anatomists, however, do not admit of the arrangement which 
 we have adopted. From the existence of cervical and lumbar ribs in the skeletons of many vertebrated ani- 
 mals, they maintain that in man the anterior half of the cervical transverse processes, and the thin plates of the 
 lumbar transverse processes, represent the ribs of the dorsal region ; while the parts truly analogous to the 
 dorsal transverse processes are, 1. In the cervical region, the posterior half of the transverse process ; 2. lo 
 the lumbar region, those projections which we have called apophysary tubercles. 
 
^ . - OSTEOLOGY. 
 
 j^ g from before backward, the wtaerior arch of the first verU' 
 
 a ' Irra. Its convexity, turned forward, is marked by a tu- 
 
 bercle (a), the anterior tubercle of the atlas. Its concav- 
 ity, looking backward, presents an oval facette, slightly 
 hollowed for articulation with the odontoid process of 
 the second vertebra. The superior and inferior borders 
 afford attachment to ligaments. 
 
 The foramen of the first vertebra is much larger than 
 that of all the others. The antero-posterior diameter, 
 ^ which in the neck and back is six lines, and in the loins 
 
 eight, is here fourteen ; the transverse diameter, eleven lines in the neck, seven in the 
 back, and ten in the loins, is here thirteen. This remarkable extent of aU the diameters 
 is not simply owing to the size of the spinal marrow at this point, for the anterior por- 
 tion of the foramen (/, ^, /) gives lodgment to the odontoid process of the second verte- 
 bra, so that the antero-posterior diameter of the part which contains the spinal cord does 
 not greatly exceed that of the foramen in the succeeding vertebrae. The transverse di- 
 ameter alone is more considerable, whence the possibility of lateral displacements or 
 incomplete luxations of the first upon the second vertebra without any marked com- 
 pression of the cord. 
 
 The notches (A h) are situated on the posterior arch at its junction with the lateral 
 masses. They are posterior to the articular processes, while in aU the other vertebrae 
 they are anterior. The superior are very deep, often converted into foramina by a 
 bridge of bone, and seem to be continuous with the foramen in the base of the trans- 
 verse process, by means of a horizontal groove which winds round behind the articular 
 process. This groove is sometimes almost converted into a complete canal. From the 
 union of these parts, viz., the notch, groove, and foramen, a twisted canal results, verti- 
 cal at first, and afterward horizontal, along which the vertebral artery runs in its pas- 
 sage into the cranium. Through the superior notch, which almost forms by itself the 
 .first intervertebral foramen, the vertebral artery and vein and the first cervical nerve 
 pass. The inferior notches present nothing remarkable, excepting that they are sufi5- 
 ciently deep to form, by themselves, the intervertebral foramina between the first and 
 second vertebrae. 
 
 There is no spinous process : its place is supplied by a posterior tubercle (i) for muscu- 
 lar insertion, analogous to the anterior tubercle, or, more correctly, resembling a spinous 
 process truncated. Sometimes, instead of a tubercle, there are only some inequalities. 
 The posterior arch (A, i, h), which forms more than half the circumference of the verte- 
 bra, consists of two strong and long plates. 
 
 The articular processes or columns, which we have remarked throughout the whole cer- 
 vical region, are very large in the atlas, and bear the name of lateral masses. This struc- 
 ture is connected with the use of the bone, which is to support the occipital condyles, 
 and, consequently, the weight of the head. 
 
 Of the four articular processes, the superior (J b) are concave, slanting inward, oval, 
 and obliquely directed from behind forward, and from without inward. Their form ex- 
 actly corresponds with the convexity of the occipital condyles (7 7, fig. 10), which they 
 receive, and for this purpose their external borders and posterior extremities are con- 
 siderably elevated. Within and below the articular surface are certain inequalities 
 (//, fig. 6), which give attachment to the transverse ligament. The inferior articular 
 processes are circular and plain ; they look downward and a little inward. 
 
 The transverse processes (c c) are very large and triangular : they have only one tuber- 
 cle, into which are inserted the principal rotatory muscles of the head : they are per- 
 forated by a foramen (e) at the base, but are not grooved on their surface. 
 
 The characteristics, then, of the atlas are, a7i annular form ; great lateral dimensions, 
 so that it surmounts the vertebral column like a capital ; a very large vertebral foramen ; no 
 body, nor spinous process ; large lateral masses, supporting very strong transverse processes, 
 which are not grooved, and have only one tubercle. 
 
 Second Vertebra, ^xis, or Vertebra Dentata {Jig. 7, side view). 
 The body is surmounted by an eminence {g, a, I, fig. 7), "Which, in the connected skel- 
 pig_ 7_ eton, corresponds with the anterior arch of the atlas. This em- 
 
 inence has received the name odontoid process, or processus den- 
 tatus, from its tooth-like form. It constitutes a species of cylin- 
 drical pivot, about half an inch in length, round which the head 
 turns ; and hence the name axis given to the entire vertebra. 
 It is attached to the body of the bone by a broad basis, is then 
 constricted, and terminates superiorly in an enlargement called 
 the head, which is rough at its summit (a), and gives attachment 
 [^i to the odontoid ligaments. The contracted portion (l) is called 
 the neck ; it is the weakest part of the process, and is, conse- 
 quently, the invEiriable seat of its fractures. This circular cob- 
 
THE VERTEBRAL COLUMN. 25 
 
 striction of the inferior part of the odontoid process contributes to maintain it in the 
 semi-osseous, semi-ligamentous ring in which it turns. Two articular facettes are seen 
 on this process : one in front {g), corresponding with the anterior arch of the atlas ; the 
 other behind (at /), for the transverse Ugament. 
 
 The body (c) of the axis presents anteriorly a triangular vertical ridge, which separ- 
 ates two lateral depressions for the attachment of muscles. The posterior surface cor- 
 responds with the vertebral canal. The greatest diameter of the inferior surface is the 
 antero-posterior : it is obliquely sloped downward and forward, and slightly concave, for 
 the reception of the body of the third cervical vertebra. This mutual reception of the 
 two bones does not take place between any of the succeeding vertebrae. 
 
 The foramen is shaped like the figure of a heart on playing cards : its antero-posterior 
 diameter is eight lines, which is two lines more than in the other cervical vertebrae, and 
 its transverse diameter is the same. This great size of the foramen of the second ver- 
 tebra corresponds with the extent of the movements between it and the atlas. 
 
 There is no superior notch, the inferior notch of the atlas forming by itself the inter- 
 vertebral foramen. The inferior notch presents nothing peculiar. 
 
 The spinous process {k, m), though of great length, is even more remarkable for its 
 breadth and thickness, presenting, as it were, in an exeiggerated degree, the characters 
 of the cervical spinous processes : its form is prismatic and triangular ; it is grooved 
 inferiorly, and terminates by two tubercles for the attachment of powerful muscles. The 
 spinous process is for the axis that which the transverse process is for the atlas, both 
 giving insertion to powerful muscles, which move the head upon the vertebral column. 
 
 The lamina, which correspond, as usual, with the size of the spinous process, are re- 
 markably strong. 
 
 The superior articular processes {d) are placed on each side of the body. Their facettes 
 are broad, flat, and almost horizontal, being slightly inclined outward. This direction 
 permits the atlanto-axoidean articulation to be the centre of all the rotatory movements 
 of the head. 
 
 The inferior articular processes (e) resemble those of the other cervical vertebrae. 
 
 The transverse processes («) are small, with only one tubercle, triangular, bent down- 
 ward, and perforated at the base by a foramen (/), or, rather, a bent canal, which is hol- 
 lowed out on each side of the body of the bone ; and is verticed in the first part of its 
 course, then horizontal. This canal, and that which we have described upon the atlas, 
 mark the winding course of the vertebral artery before it enters the cranium. 
 
 The specific characteristics, then, of the second vertebra are, the odontoid process, the 
 great size of the spinous process and the lamince, the large size and horizontal direction of 
 the superior articular processes, which are placed on each side of the body, and the shortness 
 of the transverse processes, which are triangular, and have one tubercle. 
 
 Seventh Cervical Vertebra, or Vertebra Prominens (6, fig. 1). 
 
 The body has the ordinary characters observed in the cervical vertebrae, but in size it 
 resembles that of the dorsal vertebrae, and frequently presents laterally a small impres- 
 sion for articulation with the head of the first rib. The spinous process bears the greatest 
 resemblance to those of the dorsal vertebrae : it is pyramidal, terminates in a single tu- 
 bercle, and is of great length, projecting considerably beyond the level of the other cervi- 
 cal vertebras ; hence its name of vertebra prominens. The articular processes are almost 
 vertical, and are not supported by small columns. The transverse process, although groov- 
 ed and perforated at the beise, as in all the other cervical vertebra, closely approaches 
 to the characters of the dorsal. The posterior border of the groove, or posterior root of 
 the process, is thick, tub-^rcular, and exactly similar to a dorsal transverse process, while 
 the anterior is thin and idimentary, excepting in cases where it is separated from the 
 body of the bone, and fonns a supernumerary rib. * The foramen in the base of the trans- 
 verse process is very rarely absent, but is most commonly small : in one case only I have 
 found it double. It is never traversed by the vertebral artery. 
 
 First Dorsal Vertebra. 
 
 This vertebra resembles the cervical, in having its body surmounted laterally by two 
 hook-like processes or ridges, but, in all other respects, it is strictly analogous to the 
 other dorsal vertebrae. It should be also observed, that the body presents an entire 
 facette for the first rib, and a third or fourth part of another for the second. 
 
 Eleventh and Twelfth Dorsal Vertebrce. 
 
 The eleventh dorsal vertebra presents on each side of the body an entire facette for the 
 eleventh rib. Its body is very large, and the place of the transverse process is supplied 
 by a tubercle. 
 
 The twelfth dorsal vertebra (c, fig: 1) resembles the lumbar in its body, which is scarcely 
 
 * This circumstance is one of the facts appealed to with most success by those who make the distinction of 
 transverse and costiform processes. 
 
 D 
 
go OSTEOLOGY. 
 
 smaller than that of the lumbar vertebrae, and of which the transverse diameter begins 
 to predominate. The spinous process is horizontal, strong, and quadrilateral. The 
 transverse processes are represented by tubercles, which, like those of the preceding 
 bone, are evidently continued in the lumbar region by those tubercles which we have 
 denominated apophysary. Lastly, the body presents entire articular facettes. It ia 
 distinguished from the eleventh dorsal vertebra by the curved surface of the inferior 
 articular processes. 
 
 Fifth Lumbar Vertebra. 
 
 The inferior surface of the body slopes very obliquely dowTiward and forward. The 
 transverse processes vary in size, but are generally much larger than those of the other 
 lumbar vertebrae ; the inferior articular processes, which are farther separated fix)m each 
 other, have a flat surface, and look directly forward. 
 
 These are the only vertebrae which in each region present peculiarities. Excepting 
 the first and second cervical, which have many characters quite foreign to the vertebrae 
 of the region to which they belong, it might be said of those peculiar vertebrae which 
 have been specially described, that their peculiarities are comprehended in the general 
 statement that those vertebrae which are placed at the limits of any two regions possess 
 characters belonging to both regions. 
 
 Vertebra of the Sacro-coccygeal Region. 
 
 AU the vertebrae of this region, nine in number, are in the adult state united into two 
 bones : the five superior form the sacrum, the four inferior the coccyx. 
 
 The Sacrum (rf, e^figs. 1 and 8). 
 
 The scxrum has received its name from the alleged practice of the ancients of ofFering 
 this part of the victim in sacrifice. It occupies the posterior and median part of the 
 pelvis, behind the point where this cavity articulates with the thigh bone, an arrange- 
 ment advantageous for the erect position. It is inserted, like a wedge, between the two 
 haunch bones. Above, it corresponds with the true vertebral column ; below, with the 
 coccyx. It is directed obliquely backward and downward ; hence the column represent- 
 ed by the sacrum forms an obtuse angle with the lumbar column, the projection of which is 
 anterior. This angle is denominated the promontory, or the sacro-vertebral angle {d, fig. 1 ) : 
 it is an important object of study, both with reference to the mechanism of standing, and 
 in the practice of midwifery.* The sacrum is curved upon itself, from behind forward, 
 so as to present an anterior concavity. It is the largest of all the bones of the vertebral 
 column ; hence the name of great vertebra applied to it by Hippocrates. It is proportion- 
 ally more developed in man than in any other mammiferous animal, which is connected 
 with the erect bipedal attitude and the sitting attitude which belong to him in a special 
 manner, t The form of the sacrum is that of a quadrangular pyramid with a truncated 
 apex, the base looking upward. It is symmetrical, like all the median bones, and pre- 
 sents for consideration an anterior, a posterior, and two lateral surfaces, a base, and a summit. 
 The anterior, pelvic, or rectal surface {fig. 8) forms part of the cavity of the pelvis. Its 
 Pig_ 8. concavity varies much in different individuals, and in the two sex- 
 
 es : but on this latter point there is great diversity of opinion among 
 anatomists. Some believe that it is greater in the female, whence, 
 it is said, results the advantage of a larger capacity of the pelvis, 
 and, consequently, an increased facility for the passage of the head 
 of the fcetus during parturition. Others, on the contrary, contend 
 that the male sacrum is more curved, and that of the female al- 
 most straight ; and they argue that, had the opposite been the case, 
 the coccyx, which forms a continuation of the curve of the sacrum, 
 would have been directed forward, and thus diminished the ante- 
 ro-posterior diameter of the outlet of the pelvis ; whereas, with a 
 slight curve of the sacrum, the coccyx has no tendency to project, 
 but is easily bent backward during labour. J 
 
 In order to determine the validity of these opposing statements, 
 I have compared a great number of sacra from both sexes, but I 
 could never detect any difference sufficiently marked or constant to be considered as 
 characteristic of the sex. 
 
 * The sacro-vertebral angle is most remarkable in man, because he alone is destined for the erect posture. 
 By this angle the impetus of movement transmitted from the vertebral column to the sacrum is in part de- 
 stroyed. In midwifery it explains the rarity of median positions of the vertei 
 
 t Birds, -which, like man, are biped, are also remarkable for the size of their sacrum. 
 
 t A very great curvature of the sacrum diminishes not only the antero-posterior diameter of the inferior, 
 but also that of the superior aperture of the pelvis ; and it thus opposes the ascent of the uterus from the true 
 into the false pelvis. Accouclieurs cannot too carefully study the varieties presented by the curvature of this 
 bone. The sacrum is often affected by a species of rickets, vrhen the other bones of the pelvis are free from 
 deformity ; and this fact may be easily explained by a reference to the uses of this bone in suf Dorting the 
 whole weight of the trunk. 
 
THE VEETEBRAL COLUMN. 27 
 
 The anterior concavity of the sacrum is interrupted by four transverse projections (1 
 1 1 l,Jig. 8), which correspond vi^ith the points of union of the sacral vertebrae, and are 
 analogous to the intervertebral prominences. The first is sometimes so prominent, that 
 it might be mistaken for the sacro-vertebral angle in an examination per vaginam. 
 
 On each side of the median line are the anterior sacral foramina (2 2 2), four in number, 
 the two superior much greater than the two inferior. They give passage to the anteri- 
 or branches of the sacral nerves, to the sacral veins, and some small arteries. External 
 to these are grooves for the nerves, and the attachment of the pyramidalis muscle. The 
 anterior surface of the sacrum is contiguous to the rectum, which follows its curvature. 
 Posterior, spinal, or cutaneous surface. Its convexity is exactly proportioned to the an- 
 terior concavity. 1. In the median line it presents the sacral ridge, formed by a continu- 
 ation of the spinous processes of the vertebral column. This is often entire in its whole 
 length, but sometimes interrupted : it bifurcates inferiorly, and fonns the borders of the 
 groove which terminates the sacral canal. The sacral ridge is rarely found cleft through- 
 out its whole length. 
 
 2. On each side of the median line are two shallow grooves, named the sacral grooves : 
 they are continuations of the vertebral grooves ; they are pierced by four posterior saeral 
 foramina, smaller than the anterior foramina, and differing less from each other in di£un- 
 eter. These afford passage to the posterior branches of the sacral nerves, to some veins 
 and arteries. They are bordered by two ranges of unequal projections : the first row, 
 placed interior to the foramina, represent the articular processes united together ; the 
 second, external to the foramina, are more marked, and correspond with the transverse 
 processes also united. 
 
 The lateral surfaces {d, e,fig. 1) are triangular, broad above, narrow below, where they 
 constitute mere borders. They slope obliquely from before backward and from without 
 inward, so that the sacrum is wedged between the haunch bones in an antero-posterior 
 as well as in a vertical direction. In front is a demi-oval or crescentic surface (7, fig. 
 8), compared from its shape to the human ear, and hence denominated auricular surface. 
 In the fresh state it is covered with cartilage, and articulates with the os innominatum. 
 Behind it is a very rugged surface with irregular depressions, giving attachment to the 
 posterior sacro-ihac hgaments. The sinuous border which terminates each lateral sur- 
 face inferiorly gives attaclunent to the sacro-sciatic ligaments. 
 
 The hose presents, 1. In the middle an oval facette (3,^^. 8), in all respects similar to 
 the body of a lumbar vertebra, with the last of which bones it is articulated. Behind 
 this is a triangular aperture resembling the foramen of other vertebrae, and completed 
 posteriorly by two lamince, which unite, and form a spinous process,* the commencement 
 of the sacral ridge. 2. On each side two triangular surfaces (4 4), smooth, looking for- 
 ward and upward, and constituting part of the greater or false pelvis. They are separ- 
 ated from the anterior surface of the sacrum by a blunt edge, which forms, as we shall 
 afterward see, a portion of the superior aperture of the pelvis. Behind the oval surface 
 of the body are notches, which complete the last intervertebral foramina ; and behind these 
 notches are the articular processes (5 5), which resemble the superior articular processes 
 of the fifth lumbar vertebra, and receive the inferior processes of that bone. 
 
 The apex (6) is truncated, and presents a transverse elliptical surface, which articu- 
 lates with the base of the coccyx. Behind it is the termination of the sacral groove, 
 bounded by two small apophyses, intended to unite with two similar projections of the 
 coccjrx. These are the sthoII cornua of the sacrum. 
 
 The sacral canal. The termination of the vertebral canal is prismatic and triangular, 
 wide superiorly, contracted and flattened inferiorly, where it degenerates into ar groove, 
 which is converted into a canal by ligaments. This canal lodges the sacral nerves, and 
 communicates both with the anterior and posterior sacral foramina. 
 
 The Coccyx (8, 9, jig. 8). 
 
 This consists of four, rarely of five, pieces of bone : they are flattened from before 
 backward, and diminish successively in size from the first to the last : they are common- 
 ly united together, rarely separate, the largest corresponding with the apex of the sa 
 crum ; the smallest is a mere nodule of bone, generally unattached. The wh«le knot- 
 ted-like bone, thus constituted, has a triangular shape, and follows the direction of the 
 lower part of the sacrum. It may be regarded as the rudiment of the tails of the lower 
 animals. In some cases I have seen it form a right angle, or even an acute angle with 
 the sacrum. 
 
 1 . The posterior, spinal, or cutaneous surface, is rough, for the insertion of the aponeuro- 
 sis of the gluteus maximus. 
 
 2. The anterior surface resembles the same part of the sacrum in miniature, and, like 
 it, is in immediate proximity to the rectum. 
 
 3. The borders are narrow, sinuous, and tubercular, and give attachment to the sacro* 
 sciatic ligaments. 
 
 * I have seen this spinous process completely bifurcated. 
 
W8 '='■*■ OSTEOLOGY. 
 
 4. The base is often united by bone to the sacrum, even in young subjects ; it pre- 
 sents an elliptical articular surface, exactly corresponding with that on the lower end of 
 the sacrun . Behind are two processes directed upward (cornua of the cocc3rx, 8 8, fig. 
 8), which are sometimes continuous with the small cornua of the sacrum. ExternaUy 
 are two notches, which are converted into foramina by means of ligaments, and afford 
 passage to the fifth pair of sacral nerves. 
 
 5. The apex (9), which is sometimes enlarged and sometimes bifurcated, gives attach 
 ment to the levator ani muscle. It is not uncommon to find the last pieces of the coc- 
 cyx deviating from the median line. 
 
 Of the Vertebral Column in general. 
 
 Having already described the situation of the vertebral column, we shall now consid- 
 er its dimensions as an entire piece of the skeleton. 
 
 Dimensions of the Vertebral Column. 
 
 1. The length or height of the vertebral column does not correspond with the length ol 
 the spinal marrow, which does not extend below the first lumbar vertebra. It varies at 
 different ages : most commonly it increases up to the twenty-fifth year, but occasionally 
 its growth is completed before this period. In the adult it remains unaltered, but in old 
 age it becomes shortened by the incurvation of the trunk forward, and the yielding of 
 the bodies of the vertebrsB and the intervertebral substances. This latter cause is also 
 productive of a very appreciable shortening of the trunk, sometimes to the extent of half 
 an inch, after long walking or standing. 
 
 When measured along its curvatures, the length of the column is generally two feet 
 four inches ; in vertical height it is two feet two inches. These dimensions are not ex- 
 actly proportional to the height of the individual, which depends principally upon the 
 length of the lower extremities. In this respect I have never found any marked differ- 
 ence between tall and short persons. In an adult of medium stature, the cervical por- 
 tion measures five inches and a half, the dorsal nine inches and a half, the lumbar six 
 inches and a half, and the sacro-coccygeal six inches and a half 
 
 It may be easily conceived that, in cases of abnormal curvature, the vertical height 
 must present considerable differences, while the actual length of the column may remain 
 almost constant. In the skeleton of a female affected with rickets, a vertical line, 
 stretched from the tubercle of the atlas to the base of the sacrum, measured one foot, 
 six inches, and six lines ; while a line which followed the inflections of the column, meas- 
 ured two feet eighteen lines — giving a difference of seven inches. Hence the possibil- 
 ity of a rapid and considerable increase in length in those patients who are submitted to 
 continued extension. 
 
 2. Antero-posterior dimensions. The antero-posterior diameter, at the sacro-vertebral 
 angle and in the lumbar region, is three inches ; in the dorsal region, two inches, four 
 lines ; in the middle of the cervical region, one inch, six lines. 
 
 3. Trmisverse dimensions. The transverse diameter is eighteen lines in the lumbar 
 region, thirteen in the middle of the dorsal, and twenty-two in the cervical. It should, 
 however, be remarked, that the transverse processes are included in this measurement 
 of the cervical region, but not in the others. 
 
 Direction. 
 
 The general direction of the spinal column is vertical, but it presents certain alternate 
 curvatures. There are four antero-posterior curvatures, viz., in front, a convexity in the 
 neck (a, b,fig. 1), a concavity in the dorsal region (b, c), a convexity in the loins (c, d), 
 and a concavity in the sacro-coccygeal region {d, e, /). Behind, the opposite curvatures 
 are observed. The degree of each curvature is always proportioned to that of the oth- 
 ers ; thus, if there be a remarkable projection in the cervical region, there is a corre- 
 sponding degree of concavity in the dorsal, and a proportional convexity in the lumbar 
 regions. So great, indeed, is the mutual dependance of these curvatures, that the slight- 
 est modification of one produces corresponding alterations in all the others. 
 
 There are many individual varieties of these curvatures ; their effect appears to be 
 that of augmenting the power of resistance in the vertical direction, or, at least, of di- 
 minishing the effect of vertical pressure. It may be physically demonstrated, that of two 
 similar rods made of the same materifils, that which presents alternate curves will sup- 
 port a greater amount of pressure in the vertical direction than that which is straight, 
 on account of the decomposition of forces which occurs at each curvature.* 
 
 In addition to these antero-posterior curvatures, there is at the level of the third, 
 
 * Some physiologists have even gone so far as to express by figures what the difference of resistance of a 
 'ecto-lineal vertebral column would be, as compared to one formed with curves like the spine, and have made 
 It as 1 ; 16. It has also been asserted, that the curvatures of the spinal column were the result of muscular 
 action. This is certainly not the fact. These curves are too fixed and too important to be made to dopend 
 on an agent so variable as that of muscular contraction. They are produced by the general law which regu- 
 lates the organization of the body. 
 
THE VEETEBRAL COLUMN. 29- 
 
 fourth, and fifth dorsal vertebrae a lateral inclination, the concavity of which is on the lefl 
 side. This being the exact situation in which the aorta, the principal artery of the body, 
 makes a curve downward, the older anatomists have ascribed the concavity of which 
 we speak to the curvature of this vessel. Bichat imagined it to be owing to the ahnost 
 universal habit of employing the right hand, in which action the upper part of the trunk 
 is inclined to the left, so as to afford a point of support, and, as it were, a counterbalance 
 to the action of the right arm, which inclination, by frequent repetition, becomes perma- 
 nent. According to this hypothesis, left-handed individuals should present a curvature 
 in the opposite direction, and Beclard has shown that such is in reality the case. I may 
 add, that I have always found the deviation greatest in those who used their right arm 
 in the most laborious employments. Of late years it has been supposed that the lateral 
 curvature depended upon the position of the foetus in utero ; had this been the case, it 
 should exist at birth, which, as I can affirm, 'it never does. Notwithstanding the likeU- 
 hood of Bichat's opinion, yet, if we consider that in every case in which an artery is im- 
 mediately contiguous to a bone, that bone presents a corresponding depression, it may 
 be questioned whether the opinion of the older anatoinists has not more foundation than 
 is generally admitted.* However slight this lateral incurvation may be, it always pro- 
 duces a correspondent one in the lumbar region, though in the majority of cases this is 
 scarcely perceptible. ^ 
 
 The history of abnormal curvatures or deviations belongs to pathological anatomy. I 
 shall only observe, that they are all due to the following causes : 1. The wasting of the 
 vertebrae by caries or softening. 2. Want of equilibrium between the strength of the 
 vertebral column and the weight of the body, either alone or when loaded with burdens. 
 3. Muscular traction. 4. The frequent repetition of any attitude»in which the column 
 is curved. 
 
 Figure and Aspects. 
 
 Viewed in front, the vertebral column represents two pyramids united by their bases. 
 The inferior pyramid is constituted by the sacrum and coccyx: ; the superior pyramid is 
 the true spine ; its base rests on the former, and its summit is surmounted by the atlas. 
 
 The contraction which exists at the fourth and fifth dorsal vertebra; has led to the 
 subdivision of this superior pyramid into two others, united by their summits. Other 
 subdivisions have been instituted, which we shall not point out, since they are useless. 
 What it is important to know is, that the vertebral column increases progressively in size 
 from above downward, which satisfactorily proves that man was formed for the erect posi- 
 tion. There are partial enlargements in different parts, as, for instance, in the first two 
 cervical vertebrae, in the seventh cervical, and last dorsal, &c. 
 
 Upon the whole, it may be said that the vertebral column presents in front the appear- 
 ance of a knotted cylinder ; behind, that of a triangular pyramid, bristled with eminences 
 and perforated with holes. How irregular does the spine appear when cursorily exam- 
 ined ! Yet, when viewed as a whole, and when we examine its figure and processes in 
 reference to its uses, we are lost in admiration in perceiving that there is not the small- 
 est tubercle, nor the most minute hole, nor the most trifling circumstance in its configu- 
 ration, which is not of great importance in' securing the perfection of the entire colunm. 
 
 The vertebral column presents for coilsideration an anterior, a posterior, and two lat- 
 eral surfaces, a base, and a summit. 
 
 Anterior Surface. — Here are observed, 1. The curvatures already described ; 2. The 
 range of bodies of the vertebrae, having the form of small columns piled on each other 
 and separated in the fresh state by certain prominent disks of a white colour and fibrous 
 structure. 3. A range of transverse grooves on the bodies of the vertebrae, which are 
 deeper in the aged than in the young subject. This surface presents in its transverse 
 diameters those variations which we have already noticed. The parts placed in front 
 of the vertebral column are, 1. Immediately on its anterior surface a ligamentous layer, 
 which completely invests it, with the anterior recti muscles of the head, the longi colli, 
 the crura of the diaphragm, and the psoae muscles. 2. At a greater distance the aliment- 
 ary canal, which rests on the spine at its commencement and termination, and is attach- 
 ed to it by membranous connexions, even where it advances forward to form its numer- 
 ous convolutions. 3. The organs of circulation, viz., the heart, the aorta, in almost its 
 whole extent, the carotid, vertebral, and common iliac arteries, the venae cavae, the ju- 
 gular and common iliac veins, the vena azygos, and the thoracic duct. From this posi- 
 tion of parts arises the possibility of effectually compressing the arteries against the ver- 
 tebral column, a method which has been successfully adopted with the carotid arteries 
 and abdominal aorta. It also explains the marked pulsations in the abdominal region 
 frequently observed in emaciated subjects, and often giving rise to an erroneous suspi- 
 
 * This opinion seems to be still farther corroborated by a case lately reported to the Academy of Medicine 
 by Doctor Gery, of complete inversion of the viscera, where the aorta was placed on the right side of the ver- 
 tebral column, and where the concavity, or, rather, lateral depression, was situated on tlie right side. The 
 facts of the case are satisfactorily established by M. Bonamy, who examined the subject. Positive proof was 
 obtained that this individual was not left-handed. 
 
b 
 
 30 OSTEOLOGY. 
 
 cion of aneurism. 4. The trachea and the lungs. 5. The great sympathetic nerves are 
 connected with it in its entire extent, and the ganglionic enlargements of which corre- 
 spond in number to the number of its different pieces. 
 
 Posterior Surface. — This presents, 1. In the median line, the row of spinous processes, 
 the whole of which constitute a vertical crest or ridge denominated spine, and hence the 
 names spinal column and rachis {(iaxk, spine). This ridge is far from being regular, but 
 its irregularities are all perfectly adapted for the fulfilment of the movements of the dif- 
 ferent regions. It commences with the tubercle of the first vertebra, is suddenly en- 
 larged at the second, diminishes again at the third, fourth, and fifth cervical vertebrae, 
 and projects anew at the sixth, and more remarkably at the seventh ; thence named 
 vertebra prominens. Below this point the processes become oblique, prismatic, trian- 
 gular, and with one tubercle : their obliquity increases, but they become more slender 
 from the first to the tenth : in the tenth, eleventh, and twelfth dorsal, they become hor- 
 izontal, shorter, and stronger ; and they are broad, square, rectangular, and horizontal 
 in the lumbar region. Lastly, the ridge gradually sinks down in the sacro-coccygeal re- 
 gion, when it ends by dividing into two smaller ridges, leaving between them a furrow, 
 which is continued along the coccyx. We cannot fail to perceive the importance of the 
 most trifling circumstance in the conformation of the spinal ridge, whether examined in 
 reference to physiology or pathology. 1st. In reference to physiology. This ridge must 
 be viewed as the lever of those powers which produce extension. We know that the 
 movements of extension are greatest in the cervical portion, that they scarcely exist in 
 the dorsal, and are again considerable in the lumbar. The interval between the spinous 
 processes measures the extent of motion. The three enlargements above referred to, 
 viz., that of the second cervical vertebra, that of the seventh cervical and first dorsal, 
 and that of the twelfth dorsal and first lumbar, explain these movements. The first is 
 for the articulation of the particular movements of the head, the second for the move- 
 ments of the neck, and the third for the insertion of the extensor muscles of the loins. 
 2d. In reference to pathology. The spinal ridge being the only part of the vertebral 
 column which we can see or feel in the living subject, it is clearly of the greatest im- 
 portance to study the shghtest differences which it presents, because it is thus alone 
 that we are able to judge of the extent of deviation in the column ; and yet the indica- 
 tions it affords are not absolutely certain, because the pedicles of the vertebrae being 
 susceptible of torsion, a curvature may exist in the bodies of the vertebrae without any 
 corresponding alteration of the spinous processes. 
 
 2. On each side of this median ridge are two grooves, broad and shallow in the cervi- 
 cjil, broad and deep in the upper part of the dorsal region, contracted at the lower part of 
 the back, enlarged again in the loins and at the base of the sacrum, contracted, and final- 
 ly obliterated, at the lower part of this bone. These grooves are filled by a muscular 
 mass, which, in robust individuals, projects beyond the spine, while in those who are 
 emaciated the ridge forms the most prominent part. 
 
 Lateral Surfaces. — ^These present, 1. In front, the sides of the bodies of the vertebrae 
 and their transverse grooves, which are deeper at the sides than in front, also deeper in 
 the loins than in the neck and back ; 2. In the dorsal region, facettes for the costo-ver- 
 tebral articulations ; 3. Still more posteriorly, the intervertebral foramina, equal in number 
 to that of the vertebrae. The largest of these foramina is the one situated between the 
 fourth and fifth lumbar vertebrae : from this point they gradually diminish in size to the 
 upper part of the back : in the cervical region, again, they are somewhat larger ; and in 
 the sacro-coccygeal they are double, with an anterior and a posterior opening,* in con- 
 sequence of the later2il conjunction of the false vertebrae of the sacrum. In general, 
 their dimensions are in proportion to the size of the veins which communicate between 
 the intra and the extra vertebral venous system. Between these foramina are the 
 transverse processes, which contribute to form the sides of the posterior grooves, and, 
 between the transverse processes, the articulating processes are visible. 
 
 The base and the summit of the vertebral column have been already considered, in the 
 special description of the atlas and the fifth lumbar vertebra. 
 
 Vertebral Canal. — ^This canal, into which the intervertebral foramina open, follows all 
 the curves of the spinal column, but does not altogether correspond in shape with its 
 external figure. It may be even said that its dimensions, at different heights, bear an 
 inverse proportion to those of the column ; thus, while the canal is most capacious in 
 the neck, the column, on the other hand, is largest in the loins. It has been said that 
 the widest portions of the canal correspond with the enlargements of the spinal cord : 
 but this is not correct. The capacity of the canal is proportioned to the mobility of the 
 respective portion of the column, so that, in the most extensive movements, the spinal 
 marrow is effectually guarded from compression : thus it is largest in the neck and loins, 
 and smallest in the back and sacrum, t 
 
 * [The foramina which lead from the sacred canal are single at their internal orifices, though, for the rea- 
 son given in the text, they open externally by two orifices. It is the internal orifice which answers to the 
 intervertebral foramen of the other vertebrae.] 
 
 t In the Philos. Trans., 1822, Mr. Earl has published a paper to establish this fact from observatioa in 
 comparative anatomy. 
 
THE VERTEBRAL COLUMN. 31 
 
 The canal is almost equally well protected in front and behind : anterloily by the 
 bodies of the vertebrae, posteriorly by the spinous processes, which, as it were, ward off 
 mischief from the spinal canal. Laterally it is defended by the articular and transverse 
 processes. Behind, on each side of the median ridge, it is protected by the laminae, the 
 intervals of which are filled up by what are named the yellow ligaments. Any loss of se- 
 curity occasioned by the existence of these yellow ligaments is compensated by the fol- 
 •lowing circmnstances : 1. The ligaments are very short, so that the edges of the laminte 
 are almost contiguous. 2. In the neck, where the intervals are greatest, the laminae 
 are so inclined, that the inferior border of the one above overlaps the superior border of 
 the one below. 3. In the loins, where the intervals are nearly as great, the laminae are 
 small, and their place is in a great measure occupied by the lateral masses and the pedi- 
 cles, which are proportionally increased in development. It is impossible for an instru- 
 ment to penetrate into the canal in the lumbar region, excepting between the spinous 
 processes. The same difficulty exists in the cervical region during extension, on ac- 
 count of the imbrication of the laminae. During forcible flexion, however, an instrument 
 may enter between them, when directed from below upward. 
 
 Internal Structure of the Vertebrce. 
 
 Excepting the thin external layer of compact tissue, the bodies of the vertebrae arc 
 almost entirely composed of open, spongy texture. The different processes, on the 
 other hand, have a considerable quantity of compact tissue ; but, in all places where they 
 undergo any enlargement, they are cellular. The laminae are formed almost exclusively 
 of compact tissue. This abundance of the spongy tissue explains the fact of the weight 
 of the spinal column being so inconsiderable in proportion to its size. 
 
 The venous canals are larger in the vertebrae than in any other bones. They are, for the 
 most part, arranged within the body of the bone in the following manner : A single canal, 
 directed horizontally, and from behind forward, conunences at the posterior surface of 
 the body of the vertebra ; at the distance of a few lines from its commencement, it divides 
 into two, three, or four canals, which diverge from each other, and terminate partly upon 
 the anterior surface of the bone, partly in the cells in its interior ; all these canals are 
 lined by a thin layer of compact tissue, and perforated by foramina. 
 
 Development. 
 
 The development of the vertebral column comprises, 1. That of the vertebrae in gen 
 eral ; 2. That of certain vertebrae which differ from the rest ; and, 3. That of the column 
 considered as a whole. 
 
 Development of the Vertehrcz in general. — Each vertebra is developed at first from three 
 points of ossification,* viz., one median for the body, and two lateral for the rest of the 
 vertebral ring. To these primitive points are added, at different periods, five secondary 
 or epiphysary points, viz., one for the summit of each transverse process, one for the 
 siunmit of the spinous process, and two for the body, the one on the superior surface, 
 the other on the inferior surface, where they form two very thin plates, so that at one 
 time the body of every vertebra of the spine is, in fact, a triple disk. Lastly, there is a 
 complementary point for each apophysary tubercle of the lumbar vertebrae, which gives 
 to this class of vertebrae seven secondary points of ossification. 
 
 The first osseous points generally appear in the laminae ; they precede, by some days, 
 the deposition of bone in the bodies. This law, however, as Beclard has remarked, is 
 by no means general. 
 
 The first ossific points are visible from the fortieth to the fiftieth day ; that in the body 
 occupies the centre of the cartilage, under the form of an osseous granule, which ex- 
 tends horizontally, so as to present a lenticular aspect. The points of ossification of the 
 laminae appear in the situation of the future transverse and articular processes. 
 
 The complementary osseous points are not formed until the fifteenth or eighteenth 
 year. Sometimes, however, as Bichat has observed, the point for the summit of the 
 spinous process is included among the primitive nuclei, and in such cases it is situated 
 at the place where that process becomes continuous with the laminae. 
 
 The lateral osseous points are always united together before joining the body of the 
 bone : this union commences about a year after birth ; they are not united with that oi 
 the body until about four years and a half The lateral points are so joined to the cen- 
 tral one that they form the sides of the body, and in the cervical region, from their more 
 rapid increase, they constitute of themselves fully two fifths of the body of the vertebra. 
 It is, then, on the body of the vertebra, or on what is essentially the articular part of the 
 bone, that the three primitive points are united together. The epiphysary points of the 
 transverse and spinous processes are joined to the rest from the twentieth to the twen- 
 ty-fifth year ; the union of the epiphysary laminae of the bodies is not completed imtil 
 from the twenty-fifth to the thirtieth year. 
 
 * Some anatomists admit two primitive points for the body of the vertebra. It would •xceed our limitf to 
 give an account of the discussions to which this question of osteogeny has given rise. 
 
I 
 
 88t OSTEOLOGY. 
 
 Development of particular Vertebra. — Those vertebrae which present great differences 
 of form present striking differences, also, in their mode of development ; such are the 
 atlas, axis, seventh cervical vertebra, first lumbjir, and those which constitute the sa- 
 crum and coccyx. 
 
 Adas. — Modern anatomists admit five or six points of ossification for this bone ; one 
 or two for the anterior arch, two for the lateral masses, and two for the posterior arch. 
 I have never observed more than two lateral points, the same point belonging at once 
 to the lateral masses, and half of the arch on each side. They appear in the following 
 order : those for the posterior arch make their appearance from the fortieth to the fiftieth 
 day ; those for the anterior arch not until during the first year after birth. The two 
 osseous points of the posterior arch unite together, those of the anterior arch do the 
 same, and then the anterior is united to the posterior arch. 
 
 Axis. — There are often two osseous points for the body of this bone, and always two 
 lateral ones for the odontoid process : it has, therefore, in all, five or six points, viz., 
 two for the laminae or posterior arch, one or two for the body, and two for the odontoid 
 process. Meckel and Nesbit admit one other nucleus between the odontoid process and 
 the body, which appears in the course of the first year after birth. The points in the 
 laminae appear from the fortieth to the fiftieth day ; those in the body during the sixth 
 month ; and those in the odontoid process, a short time after. At birth the body of the 
 axis is proportionally more developed than that of the other vertebrae. The union of its 
 several parts takes place in the following order : the two laminae are joined together 
 shortly after birth ; the two points of the odontoid process remain distinct during the 
 whole of the first year ; the body and the odontoid process are united in the course of 
 the third year ; and the laminae and the body during the fourth or fifth year. 
 
 Seventh Cervical Vertebra. — Independently of the osseous points common to all the 
 vertebra;, this bone has two others situated on each side of the body in the cartilage 
 which forms the anterior half of the transverse process. The existence of this point, 
 which was described by Hunauld, but which does not appear to me to be constant, 
 establishes an analogy between the transverse processes of the cervical vertebrae and 
 the ribs ; it represents in a rudimentary state the permanent cervical ribs of some ani- 
 mals ; and explains an anomaly which is not very uncommon in the human subject, viz., 
 the existence of a supernumerary cervical rib. 
 
 First Luvibar Vertebra. — Its transverse process is sometimes developed by a point which 
 remains separate from the body of the bone, and forms a supernmnerary lumbar rib. 
 
 Development of the Sacrum and Coccyx. — The first three sacral vertebrae each present 
 five primitive points, viz., one for the body, two for the laminae, and two for the anterior 
 portion of the lateral masses. The last two sacral vertebrae have only three points. 
 
 Each of the coccygeal vertebrae is developed from one point only, but it is not uncom- 
 mon to see the first two formed by two lateral points, which subsequently unite in the 
 median line : there are, therefore, twenty-one primitive points in the sacrum, and four 
 in the coccyx. Subsequently two epiphysary laminae are formed for the body of each 
 sacral vertebra, making ten new complementary osseous points. At a still later period 
 two laminae are developed, one on each side of the sacrum, corresponding with the au- 
 ricular surface, so that the whole number of osseous points in the sacrum is thirty-three. 
 
 Ossification proceeds more slowly in the sacral and coccygeal vertebrae than in the 
 others : it commences in the body, the first points appearing from the second to the third 
 month in the first three sacral vertebrae, from the fifth to the sixth month in the fourth 
 and fifth vertebrae ; the laminae begin to ossify in the interval between the sixth and 
 ninth month : the first vertebra of the coccyx usually begins to ossify during the first 
 year after birth ; the second, from the fifth to the tenth ; the third, from the tenth to the 
 fifteenth ; and the fourth, from the fifteenth to the twentieth year. 
 
 The union of the osseous points takes place at different times ; the osseous pieces of 
 each vertebra are first joined together, and subsequently the vertebrae themselves. 
 
 1. Union of the Osseous Nuclei of each Vertebra. — The osseous points of the laminae are 
 first united ; these then join with the anterior lateral nuclei of the first three vertebrae : 
 at a much later period the lateral masses become connected with the body. 
 
 The union of the lateral masses with the body takes place much earlier in the fourth 
 and fifth sacral vertebrae than in the three others, though these latter first showed osse- 
 ous points. After the union of the lateral masses, the sacrum is composed of five pieces, 
 which remain separate until the fifteenth year. 
 
 2. Union of the Sacral Vertebra, with one another. — This process commences between 
 the fifteenth and eighteenth year, at which time the epiphysary laminae of the bodies of 
 the sacral vertebra; are developed. At the age of twenty-five the epiphysary laminae of 
 the iliac surface of the sacrum are developed. The union commences with the lower 
 vertebrae, and proceeds upward. The first is not completely joined to the others until 
 from the twenty-fifth to the thirtieth year. 
 
 The union of the body of each vertebra with its epiphysary laminae proceeds from the 
 circumference to the centre, so that, in a vertical section of a sacrum, which is com- 
 pletely ossified externally, we often find an intermediate lamina of cartilage. I have 
 
THE SCULL. 33 
 
 Observed this cartilage between the first and second sacral vertebrae in subjects of a 
 yery advanced age. 
 
 The union of the pieces of the coccyx takes place sooner than those of the sacrum. 
 It commences with the first two pieces ; the third and fourth then follow ; and, in the 
 last place, the second and third are united. Towards the fortieth or fiftieth, or some- 
 times the sixtieth year, the coccyx becomes united to the sacrum. This junction is 
 later in the female than in the male ; sometimes it never takes place. 
 
 Development of the Spine in general. — Up to the end of the first month of conception, 
 the length of the spine is commensurate with that of the body, the extremities as yet 
 only existing under the form of small tubercles. This disproportion between the spine 
 and members is gradually effaced by the elongation of the limbs, so that at birth the 
 vertebral column does not constitute more than three fifths of the height of the subject. 
 In the adult it forms only two fifths. / 
 
 All the parts which concur in forming the canal for the defence of the spinal cord are 
 developed prior to those which are specially devoted to locomotion, as is shown in the 
 development of the laminae, as compared with that of the body and processes. The os- 
 sification of the laminae proceeds in regular succession from above downward, from the 
 neck to the sacro-coccygeal region. The ossification of the bodies takes a different 
 course, commencing in the dorsal region as a centre, and proceeding to either extremity 
 of the column. The ossification of the bodies of the vertebrae commences in the centre 
 of the bone, and accordingly, if the spine of a foetus be dried, the cartilages shrink, and 
 the series of osseous nodules, which represent the bodies of the vertebrae, look like 
 grains of Indian corn strung together. 
 
 In the first periods of its development, the spinal column presents the following re- 
 markable differences from its subsequent condition. It is completely devoid of curva- 
 ture, and instead of resembling in shape a pyramid with the base below, it is precisely 
 the reverse, the base of the pyramid being uppermost. As the child grows up, the spine 
 gradually acquires those characters which it presents in the adult. In the old subject it 
 is always more or less bent forward. It is not uncommon to meet with several dorsal 
 or lumber vertebrae more or less completely united by a layer of bone, which forms a 
 sort of sheath or clasp. To this I have apphed the name of Emchylosis by invagination. 
 
 THE SCULL. 
 
 Composed of the Cranium and Face. — Cranial Bones. — Occipital. — Frontal. — Sphenoid.— 
 Ethmoid. — Pafielal. — Temporal. — The Cranium in general. — Development. — Bones of 
 the Face. — Superior Maxillary. — Palate. — Malar. — Nasal. — Lachrymal. — Inferior Tui 
 binated. — Vomer. — Inferior Maxillary. — The Face in general. — Cavities. — Development 
 
 The scull is the most complicated portion of the skeleton. It has been more minute- 
 ly investigated than any other part, probably on account of the difficulty of the study. It 
 is composed of two distinct portions : one, the cranium, designed to enclose and protect 
 the brain ; the other, the face, which affords lodgment to almost all the organs of the 
 senses, and, at the same time, is employed in the function of mastication. 
 
 The Cranium. 
 
 The cranium {Kpdvog, a helmet) is a round osseous case, composed of eight bones, 
 that is, of eight pieces, distinct and separable after the complete development of the 
 skeleton. Four of these are single, and placed on the median line, viz. (counting from 
 behind forward), the occipital, the sphenoid, the ethmoid, and the frontal ; the remaining 
 four are in pairs, and are situated laterally, viz., the two parietal and the two temporal. 
 To these must be added the two small supernumerary bones denominated ossa wormiana, 
 or triquctra. 
 
 The Occipital Bone (Jigs, 9 and 10). 
 
 The occipital bone occupies the posterior, inferior, and middle portion of the cranium, 
 a great part of the base of which it constitutes.* Below it is articulated with the ver- 
 tebral column ; in front with the sphenoid ; and it is, as it were, wedged in between the 
 parietal and temporal bones of the right and left sides. It is broad and symmetrical ; 
 in shape, an irregular segment of a spheroid, notched round the circumference. It has 
 an anterior and a posterior surface, and a circumference having four borders and four angles. 
 
 The posterior or cutaneous surface {fig. 9) is convex, and presents the inferior orifice of 
 the occipital foramen (1, fig. 9 ; d, fig. 21), (foramen magnum), the largest of all the fora- 
 mina in the skeleton, excepting the sub-pubic, or obturator foramen of the os innomina- 
 
 * It is the OS prora: of Fabricius of Aquapendente, who, following out the same metaphor, has given tb« 
 name of os puppis to the frontal, and os carinoe to the sphenoid. 
 
 E 
 
H. 
 
 OSTEOLOGY. 
 
 turn. It gives passage to the spinal marrow with its envelopes, the spinal accessory 
 
 Fig. 9. 
 
 nerves, and vertebral arteries. In front of the foramen is the 
 inferior surface of the basUar process (2, fig. 9 ; n, fig. 21), 
 which forms the bony roof of the pharynx ; it is placed hor- 
 izontally, is rough, and has a ridge in the median line, more 
 or less prominent in different subjects. Behind the foramen, 
 and in the median line, is the external occipital ridge {perpe-ndic' 
 ular spine) (3 4,^^. 9; c a, fig. 21), extending from the poste- 
 rior edge of the foramen to the external occipital protuberance. 
 This projection is wanting in some individuals, and in others 
 its place is occupied by a depression. On each side of the 
 ridge are unequal surfaces, bounded above by a line, with the 
 concavity looking downward. Thus, the siiperior semicirctdar 
 line (5 5, fig. 9 ; a b,fig. 21) commences at the occipital protu- 
 berance (4, fig. 9 ; a, fig. 20), and proceeds horizontally out 
 ward. The irregular surface included between this line and 
 the foramen is again divided by a line whose concavity is directed upward (6 6, fig. 9), 
 and which is called the inferior semicircular line. These lines and these inequalities 
 are destined to receive the insertion of a great number of muscles. 
 
 On each side of the occipital foramen, and towards the fore part, are the condyles (7 7, 
 fig. 9 ; e,fig. 21), two articular eminences, convex, elliptical, directed from behind for- 
 ward, and from without inward, their surfaces looking downward, and somewhat out- 
 ward. They articulate with the atlas. Behind these are two fossae : the posterior con- 
 dyloid, which are often perforated by an aperture ; the posterior cmidyloii foramen (8, figs. 
 9 and 21), giving passage to a vein. In front, and external to the condyles, are the an- 
 terior condyloid fosscz and foramina (9 9, fig. 9) ; the latter are really flexuous canals, 
 through which the hypoglossal nerves pass out of the scull. External to the condyles 
 is a rough surface, the jugular surface {i,fig. 21), which gives attachment to the recti 
 laterales muscles of the head. 
 
 The anterior internal or encephalic surface {fig. 10), in common with all the other bones 
 
 Fig. 10. 
 
 of the cranium, is lined by the dura mater. It presents, 1. 
 The internal orifice of the occipital foramen {I, fig- 10), which 
 is larger than the external. 2. Before the foramen the ba- 
 silar groove (2), sloping gently from above downward and 
 backward : the sides- of the groove are marked by other 
 very small grooves, which concur in forming the inferior 
 petrosal groove. 3. On each side of the occipital foramen, 
 and towards the fore part, is a projection (3 3) which corre- 
 sponds with the condyle, and particularly with the anterior 
 condyloid canal. 4. A little more external and posterior is 
 a small portion of a groove (4), which contributes to form 
 the termination of the lateral sinus. 5. Behind the foramen 
 are the four occipital fossce, two superior or cerebral (5 5), and 
 two inferior or cerebellar (6 6), separated frohi each other by 
 a crucial ridge. The vertical branch of this ridge {g a) joins 
 the termination of the sagittal groove above ; below it is 
 formed by the internal occipital crest (7). The horizontal 
 branches (_g b) correspond with the grooves for the lateral 
 sinuses of the dura mater. The internal occipital protuberance (g) is situated at the conflu- 
 ence of the four branches. The right and left lateral grooves are rarely of the sEime 
 size and depth ; the right is generally the larger, and forms by itself the continuation of 
 the sagittal or longitudinal groove. 
 
 The circumference presents four borders and four angles. The superior or parietal bor- 
 ders (a b, a b), which are remarkable for the length of their indentations, articulate with 
 the posterior borders of the parietal bones forming the lamdoidal suture. 
 
 The inferior or temporal borders (b c, b c) are divided into two equal portions by the jugu^ 
 lar eminence {d), which articulates with the temporal bone. This eminence, in most sub- 
 jects small, in some instances is largely developed, so as to form a true jugular process. 
 I have seen this process articulated to the transverse process of the atlas. The part 
 (J d) above this eminence is slightly denticulated, and united to the mastoid portion ot 
 the temporal bone ; the part {d c) below is thick, sinuous, but without indentations, and 
 articulates, by juxtaposition, with the petrous portion of the temporal. In front of the 
 jugular eminence is a deep notch, sometimes divided into two parts by a process of 
 bone, which contributes to form the foramen lacerum posterius. 
 
 The superior angle (a) is acute, and is received into the retreating angle formed by 
 the posterior borders of the parietal bones. Its place is sometimes supplied by a Wor- 
 mian bone. In the young subject, the posterior fontanelle is placed here. The inferior 
 angle (c) is truncated, and very thick ; it forms the basilar process, which presents a rough 
 articular surface for union with the body of the sphenoid. The connexion is estabUshed 
 
FRONTAL BONE. 35 
 
 by means of a cartilage, which becomes ossified at a very early period, so that many 
 anatomists describe the sphenoid and occipital as one bone.* 
 
 The lateral angles {b b) are very obtuse, and are received into the retiring angle formed 
 by the union of the parietal with the temporal bone. At these angles the latcreU and pos- 
 terior fmitanelles are situated. 
 
 Connexions. — The occipital articulates with six bones ; the two parietal, the two tem- 
 poral, the sphenoid, and the atlas. 
 
 Structure. — The part of this bone which forms the occipital fossae consists almost ex- 
 clusively of compact tissue. It is here extremely thin, especially at the inferior fossse. 
 In the rest of its extent there is spongy tissue between the two tables. The external 
 table is much thicker and less brittle than the internal, which is named vitreous, on ac- 
 count of its fragility. The spongy tissue is very abundant in the condyles and in the ba- 
 silar process. 
 
 Development. — The occipital bone is developed from four points : one for the squamous 
 portion, that is, the part of the bone behind the foramen magnum ; one for each lateral 
 condyloid portion of the occipital, and one for the anterior or basilar portion. These 
 four parts are considered by some anatomists as so many distinct bones, which they de- 
 scribe under the names of posterior or superior occipital, lateral occipitals, and anterior 
 occipital or basilar bone. The first point of ossification appears in the squamous or back 
 part of the bone, under the form of a small oblong plate, placed transversely in the situ 
 ation of the protuberances. I have never seen this piece formed by two lateral points. 
 The part of the bone of which we are speaking is always visible towards the middle of 
 the second month. The condyloid portions make their appearance next, and, lastly, the 
 basilar portion, which I have never seen developed from two lateral points. In a foetus 
 of two months and a half, the ossified part of this process presented the appearance of a 
 linear streak, situated exactly in the median line, and directed from before backward. 
 The four points of ossification are finally united at the foramen magnum. 
 
 Anatomists, however, are not at all agreed respecting the number of points of ossifi- 
 cation. Meckel admits eight for the posterior part of the bone, two for the condyles, and 
 one for the basilar process. Beclard, on the other hand, admits only four in the poste- 
 rior part of the bone. His opinion is founded upon the existence of four fissures or di- 
 visions at the circumference of this portion ; viz., one at the superior angle, which 
 sometimes gives to the posterior fontanelle the lozenge shape of the anterior ; one be- 
 low, which is nothing more than a slight notch in the back of the foramen magnum ; 
 and two on each side, corresponding to the posterior lateral fontanelles. The opinion 
 of Meckel is perhaps grounded upon certain abnormal cases, in which this part of the 
 bone is divided into a considerable number of pieces, resembhng so many Wormian 
 bones united by suture. 
 
 The Frontal or Coronal Bone {jigs. 11 and 12). 
 
 The frontal bone is situated at the anterior part of the scull, and above the face. It 
 is symmetrical, and represents a considerable segment of a hollow sphere. From its 
 shape it has been compared to a shell. The superior three fourths are curved, placed 
 vertically, but more or less inclined from above downward and forward ; the inferior 
 fourth is flat and horizontal. It has an anterior, a posterior, and an inferior surface, and 
 three borders. 
 
 The anterior cutaneous or frontal surface is smooth and convex ; there is a suture in 
 the median line in young subjects, which in the adult is ^ig. 11. 
 
 obhterated, leaving scarcely any trace of its existence, ex- 
 cepting at its termination below. At this spot there is a 
 prominence named nasal eminence or glabella (or middle 
 frontal eminence) {I, fig. 11). 
 
 On the sides of the median line, proceeding from above 
 downward, we observe two smooth surfaces ; then the 
 frontal eminences (2 2), two projections which are most 
 strongly developed in young subjects ; and below these, on 
 each side of the glabella, the superciliary ridge, an arched 
 elevation which forms the margin of the orbit, and is more 
 prominent towards the nose than externally. Quite at the outside of'the anterior sur- 
 face of the frontal, there is a small, depressed, triangular surface (4), which looks directly 
 outward, and is separated from the frontal eminence by a sort of crest, running upward 
 and backward (5) : it forms the anterior part of the temporal fossa. 
 
 The anterior surface of the frontal bone is separated from the skin by the frontal, or- 
 bicular, and corrugator supercilii muscles, and the anterior portion of the cranial apo- 
 neurosis. 
 
 The inferior or orbito-ethmoidal surface {fig. 12) presents in the middle a large rectan- 
 
 * A reference to comparative anatomy would seem to justify this view, for in some inferior animals the 
 basilar process and the sphenoid are but one piece. 
 
OSTEOLOGY. 
 
 '.W*!V't'^ ■ gular notch (6), which extends the whole length of this 
 surface from before backward. This notch, which is 
 named ethmoidal, because it receives the ethmoid bone, 
 has, 1. In front, and in the median line, a prolongation, 
 denominated the nasal spine (7) : this spine is rough in 
 front, for articulation with the proper nasal bones : be- 
 hind it is marked by two grooves, separated by a verti- 
 cal ridge ; the ridge joins the perpendicular lamella of the 
 ethmoid, and the two grooves form part of the vault of 
 the nasal fossae. 2. Farther back, and on each side, is 
 the large opening of the frontal sinuses. 3. The two 
 borders of the notch are marked with {b d, b d) incom- 
 plete cells, which join with those of the ethmoid. 4. On 
 the same borders there are two, or sometimes three 
 ^''a small grooves, which contribute to form the anterior and 
 
 posterior internal orhitary canals. 
 
 On each side of the notch is the orbital plate (9 9), triangular and concave, especially 
 towards the external margin, where there is an excavation for the lachrymal gland {fos- 
 sa glandula lachrymalis). At the internal margin there is a small depression for the at- 
 tachment of the cartilaginous pulley, in which the tendon of the superior oblique muscle 
 of the eye is reflected. 
 
 The posterior or cerebral surface is concave, and marked by eminences and depressions 
 corresponding to the sulci and convolutions of the brain, and by furrows for arterial 
 branches. In the median line is a longitudinal groove, the sides of which unite below, 
 and form the frontal ridge, which terminates in a foramen called foramen cacum. The 
 ridge is sometimes absent, and occasionally the place of the foramen is occupied by a 
 notch, completed by the ethmoid, as already described. On each side of the median line 
 are the frontal fossce, which are deeper than the corresponding eminences on the outside 
 seem to indicate : below are the orbital prominences, which look directly upward, and form 
 a retiring angle* with the frontal fossae ; they are covered with acuminated eminences, 
 which are received into the anfractuosities of the brain. 
 
 The superior or parietal border {b a b) is semicircular, denticulated, and cut obliquely at 
 the expense of its internal plate above, and of its external below, and at the sides. In 
 the middle, it forms a very obtuse angle (a), which is received into the retiring angle 
 formed by the parietal bones. In young subjects this angle is wanting ; in its situation 
 the anterior angle of the anterior fontanelle is placed. 
 
 The inferior or sphenoidal border {b b b) is very short, thin, and straight, interrupted by 
 the ethmoidal notch, and adapted to the smaller wings of the sphenoid. It terminates 
 externally at its junction with the superior border, by two triangular surfaces slightly in- 
 dented, which articulate with the greater wings of the sphenoid. 
 
 The anterior or orUto-nasal border (c c, fig. 11) presents in the centre the nasal notch {d d), 
 articulated in the middle with the nasal bones, and at the sides with the ascending pro- 
 cesses of the superior maxillae. At the bottom of this notch is the anterior surface of 
 the nasal spine. On each side we observe the orbital arch (c d), more sharp and thin to- 
 wards its outer end. At the junction of the internal with the two external thirds of this 
 arch is situated a foramen (c), or, more frequently, a notch converted into a foramen by 
 a ligament ; it is called the superciliary or supra-orbital foramen, and gives passage to the 
 frontal vessels and nerves. At the bottom of this notch there are generally one or more 
 vascular openings, which lead into the diploe, and are the terminations of venous canals, 
 which run for a considerable way within the bone. The orbital arch terminates on each 
 side by a process ; the inner one, internal angular process (d), is broad and thin, and artic- 
 ulates with the OS unguis ; the external (c) is thick, and unites with the malar bone. 
 
 Connexions. — The frontal is articulated with twelve bones : the two parietal, the 
 sphenoid, the ethmoid, the two nasal and two malar bones, the ossa unguis, and the 
 two superior maxillary. 
 
 Internal Structure. — The vertical portion and external orbital processes are very thick ; 
 the horizontal part is very thin, and hence the facility with which instruments can pen- 
 etrate the cranium through the roof of the orbit. It contains large c&xiiies, frontal sinu- 
 ses (a, figs. 23 and 24), which open in the ethmoidal notch, and add greatly to the thick- 
 ness of the bone at its lower part. They are separated by a septum, which is often bent 
 to one side, and is generally imperfect. The capacity of these sinuses is very variable ; 
 they often extend throughout the whole of the orbital plates, almost to the edge of the 
 sphenoid. The study of these sinuses, which are connected with the organ of smelling, 
 is of great importance in determining the facial angle. 
 
 Development. — The frontal bone is developed from two lateral points of ossification, 
 which appear about the middle of the second month, and conunence in the orbital arches. 
 At this time the edges are in approximation below, but above are separated by an angular 
 
 * This retiring angle measures pretty exactly the facial angle. 
 
SPHENOID BONE. 
 
 3f 
 
 interval, which forms the anterior angle of the anterior fontanelle. The two pieces are 
 united by suture during the first year ; it is gradually effaced afterward, being longest 
 visible at its inferior termination, though it is uncommon to find it permanent through 
 life. Independently of these general changes which the bone undergoes in the course 
 of its development, there are also certain peculiar alterations in which the sinuses are 
 concerned. These cavities make their appearance during the first year, and gradually 
 increase in size, not only up to the period of manhood, but even to old age. 
 
 The Sphenoid Bone {figs. 13 and 14). 
 
 This bone has received its name from the Greek word a^rjv [S. wedge,) because it is 
 inserted like a wedge between the other bones. It is situated at the anterior and mid- 
 dle part of the base of the cranium {fig. 23). Almost ^ j3 
 all anatomists agree in considering it as a separate 
 bone ; but Soemmering and Meckel describe it as united 
 with the occipital, under the name of basilar or spheno- 
 occipital bone. It is a single and symmetrical bone, con- 
 sisting of a bodi/ or central part, from which spring, on 
 each side, two horizontal portions, the greater and less- 
 er wings of the sphenoid ; and below two vertical col- 
 umns, the pterygoid processes. It has been compared to 
 a bat with extended wings. We shaU consider it as 
 divided into a body and lateral parts. 
 
 The body, or central part, is of a cubical form, and therefore presents six surfaces. 
 
 Superior or cerebral surface {of a d,fig. 13). Proceeding from before backward, we 
 observe, 1. A smooth plane surface (a), slightly depressed on each side, over which the 
 olfactory nerves pass. 2. A transverse groove, optic groove {b), on which the commis- 
 sure of the optic nerves rests, and which is continuous on each side with the optic fora- 
 men (1 1).* 3. A deep quadrilateral fossa (c), in which the pituitary gland is lodged, 
 called the sella turcica, supra-sphe7ioidal, or pituitary fossa. 4. On the sides of this fossa, 
 two grooves, named cavernous or carotid grooves, because they correspond to the carotid 
 arteries and cavernous sinuses. Anteriorly the cavernous groove gives attachment to 
 the ligament of Zinn, a tendon which gives origin to three muscles of the eye. Near its 
 anterior termination, and between it and the pituitary fossa, is the middle clinoid process,^ 
 generally nothing more than a simple tubercle, but sometimes sufficiently developed to 
 unite either with the anterior or with the posterior clinoid processes, the former case 
 being the more common. 5. Behind the pituitary fossa we observe a quadrilateral plate 
 {d), directed obliquely from above downward and backward ; its anterior surface 
 forms part of the fossa, its posterior surface is continuous with the basilar groove, its 
 lateral edges are notched for the fourth and sixth pair of nerves, and the superior border, 
 which separates the basilar groove and the pituitary fossa, presents, at each extremity, 
 an angular process (e), the posterior clinoid (from kIivt], a bed, from a supposed resem- 
 blance of the anterior and posterior clinoid processes to the four corners of a bed). 
 6. From the lateral and anterior parts of the body of the sphenoid arise two triangular pro- 
 cesses (n 0, n o), flattened above and below, extremely thin and fragile, and directed 
 transversely : these are denominated the orbital or lesser wings of the sphenoid {alee mi- 
 nores), or the wings of Ingrassius, from the anatomist who first gave a good description 
 of them. The superior surface of these processes is flat, and corresponds to the ante- 
 rior lobes of the brain ; the inferior surface forms part of the roof of the orbits ; the ante- 
 rior edge is bevelled below, and rests upon the posterior border of the frontal and the eth- 
 moid ; the posterior edge is thin and sharp externally, thicker internally, and divides the 
 anterior and middle fossae of the base of the cranium ; the summit (o) is pointed, and 
 hence the processes are sometimes called ensiform or xiphoid ; the base presents the in- 
 ternal orifice of the optic canal or foramen (1), which is directed outward and forward, 
 and gives passage to the optic nerve and the ophthalmic artery. The base of the lesser 
 wing terminates behind in a projecting angle (w), which forms the anterior clinoid process ; 
 and beneath this is a deep notch, sometimes a foramen, for the carotid artery. Occasion- 
 sdly the anterior are united to the posterior clinoid processes by a long bridge of bone. 
 
 AH the part of the sphenoid in front of the sella turcica, including the smaller wings, 
 forms the anterior sphenoid of some modern anatomists. In this portion of the bone the an- 
 terior fossae of the base of the cranium are situated. The remaining portion of the bone, 
 placed inferior to the former, constitutes the posterior sphenoid, and in this the middle 
 fossae are situated. The separation of these two parts, which is but temporary in man, 
 existing only during the early months of foetal Hfe, is permanent in quadrupeds. 
 
 The inferior or guttural surface of the body {fig. 14) presents, in the median hne, a 
 ridge or crest, called the beak of the sphenoid or rostrum {g) ; it is more prominent anteri- 
 orly than posteriorly, is received into a groove of the vomer, and is continuous with the 
 
 * [The groove is formed on an eminence named the olivary process.^ • j i, 
 
 f When the middle clinoid processes are united with the posterior, they are then also joined to the anterior. 
 
OSTEOLOGY 
 
 ' %nterior ridge of the body of the bone. On each 
 side is a deep furrow concealed by a lamella (on each 
 side of g), under which the edges of the vomer are 
 insinuated. At the bottom of this furrow is seen 
 the orifice of a temporary canal, which exists only in 
 young subjects, and which, passing obliquely through 
 the sides of the bone, opens in the sphenoidal fissure. 
 This canal is the trace of the still incomplete union 
 of the anterior and posterior sphenoid ; it disappears 
 as soon as the sinuses within the bone are developed. 
 More externally, and on the same surface, is situated 
 a small groove running from before backward, which 
 lorms part of the ptery go-palatine canal, along which an artery of the same name passes. 
 Still more externally are the pterygoid processes (6 m h) {Trrepv^, ala), two large projections 
 directed perpendicularly downward. In front their surface is broad above, where it forms 
 part of the pterygo-m2ixilIary fossa, and rough below, for articulation with the palate bone. 
 Behind is a deep fossa, into which the internal pterygoid muscle is inserted : it is named 
 the pterygoid fossa, and is formed by two laminae, named the external and internal ptery- 
 goid plates, of which the external (b) is the broader, and the internal (m) the longer. At 
 the upper part of the internal plate is an elliptical depression called the scaphoid fossa, 
 which gives attachment to the circumflexus palati muscle. The internal surface of the 
 pterygoid process contributes to form the external wall, and posterior opening of the na- 
 sal fossa {h i, fig. 25). The outer surface of the external plate is broad, forms part of 
 the zygomatic fossa, and gives attachment to the external pterygoid muscle. Tlie base 
 of the pterygoid process is pierced from before backward by the vidian or pterygoid canal 
 (6 6, Jig. 14) ; its summit is deeply bifurcated, to receive the tuberosity of the palate bone. 
 The internal branch of this bifurcation (internal pterygoid plate) is very delicate, and is 
 curved into a hook-like process (s) {hamular process), round which is reflected the tendon 
 of the circumflexus or tensor palati muscle. 
 
 The anterior or ethmoidal surface of the body of the sphenoid presents, 1. Above and 
 in the median line, a small horizontal projecting angle {f,figs. 13 and 14), which artic- 
 ulates with the posterior border of the cribriform plate of the ethmoid. 2. Below this, a 
 vertical ridge {f g,fig. 14), continuous with the septum of the sphenoidal sinuses, and 
 articulating with the perpendicular lamella of the ethmoid. 3. On each side the open- 
 ings of the sphenoidal sinuses (7 7). These are two in number ; they are separated 
 from each other by a septum, which inclines sometimes to the right side, sometimes to 
 the left, and are subdivided into a number of irregular cells. They are wanting in the 
 young subject, but acquire a great size in the adult, occupying the whole body of the 
 sphenoid, and extending into the base of the lesser wings, and even occasionally into the 
 substance of the palate bone. External to the irregular orifice of the sphenoidal sinuses 
 is a rough surface, which articulates above with the lateral masses of the ethmoid, and 
 below with the palate bone. The orifice of the sinus is in a great measure closed by a 
 lamina of very variable shape, curved upon itself, and designated sphenoidal turbinated, or 
 triangular hone {cornu sphenoidale, ossiculum Bertini) {t t, and fgs. 15 and 16, c c). This 
 plate, which remains separate for some time, appears as if it arose from the upper part 
 of the palate bone, and formed the anterior and part of the inferior wall of the sinus. It 
 is not unusual to find it united either to the palate bone or to the ethmoid. 
 
 The posterior or occipital surface {u,fig. 13) is quadrilateral, rugged, and irregular ; it 
 articulates with a corresponding surface on the basilar process of the occipital bone, by 
 means of a cartilage, which is very early ossified. On the posterior aspect of the bone is 
 situated the posterior orifice of the vidian canal. 
 
 The lateral surfaces of the body of the sphenoid pass into the base of the great icings, 
 which we shall next describe. 
 
 Great or temporal wings {y z). This portion of the bone consists of two large triangu- 
 lar prolongations, on which there are three surfaces : a superior, an anterior, and an in- 
 ferior ; two borders, an external and an internal ; and two extremities, an anterior and a 
 posterior. 
 
 Superior or cerebral surface (y 2 z). This surface, which forms part of the middle fossa 
 of the base of the cranium, is concave, quadrilateral, and marked by cerebral impressions 
 and vascular furrows. Towards its inner part, and proceeding from before backward, 
 we observe, 1. The superior maxillary forameii (3), or foramen rotundum, directed obliquely 
 forward and outward, which gives passage to the superior maxillary nerve. 2. The in- 
 ferior maxillary foramen, or foramen ovale (4), which perforates the bone directly from 
 above downward, and transmits the inferior maxillary nerve. 3. The foramen spinosum, 
 or spheno-spinosum (5), which is the smallest of the whole, and gives passage to the mid- 
 dle meningeal artery. 
 
 External or temporo-zygomatic surface. This surface is divided into two parts by a 
 transverse ridge ; the superior or temporal {l,Jig- 14) forms part of the fossa of the same 
 name, and gives attachment to the temporal muscle ; the inferior (p) fonns the upper 
 
SPHENOID BONE. ^ 
 
 part of the zygomatic fossa, and gives attachment to the external pterygoid muscle. On 
 this last part we perceive the inferior orifices of the oval and spinous foramina. 
 
 Anterior or Orbital Surface. — This surface {w w) is four-sided and smooth, and forms the 
 greater part of the external wall of the orbit. Its superior border unites with the frontal 
 bone ; the inferior forms part of the spheno-maxillary fissure. The internal border con- 
 tributes to form the sphenoidal fissure, and has a small tubercle near its inner termina- 
 tion. The external joins the malar bone. 
 
 Internal Border. — This border is convex, and commences in front by a triangular and 
 very rough surface (y y,fig. 13), which articulates with a corresponding surface on the 
 frontal bone ; it then forms part of the sphenoidal fissure (2), and finally bends outward 
 to join the petrous portion of the temporal bone : in this place it is grooved for the lodg- 
 ment of the cartilaginous portion of the Eustachian tube. The sphenoidal fissure, or 
 foramen lacerum superius (2 2, figs. 13 and 14), partly formed in the way we have described, 
 is completed by the lesser wing of the sphenoid. Wide at its internal extremity, it be- 
 comes narrow at its outer end, where it is closed by the frontal bone at o. It gives pas- 
 sage to the third, fourth, the ophthalmic branch of the fifth, and the sixth pair of nerves, 
 to the ophthalmic vein, and to a prolongation of the dura mater. At the internal extremity 
 of the fissure there is a furrow, which is occasionally converted into a foramen for the pas- 
 sage of a recurrent branch of the ophthalmic artery, which goes to the dura mater. 
 
 The external border is concave, bevelled on the outside superiorly, and on the inside 
 inferiorly, for articulation with the temporal bone. 
 
 The anterior extremity is very thin (behind y, fig. 13), and bevelled on the inner side for 
 articulation with the anterior and inferior angle of the parietal. 
 
 The posterior extremity presents a vertical process (z), the spine or spinous process of 
 the sphenoid, which is received into the angle formed by the union of the squamous and 
 petrous portions of the temporal bone, and gives attachment to the internal lateral liga- 
 ment of the inferior maxilla, and the external or anterior muscle of the maUeus. 
 
 Connexions. — The sphenoid articulates with all the bones of the cranium, and with 
 the palatine, vomer, and malar bones of the face. 
 
 Structure. — The most remarkable circumstance in the structure of the sphenoid is the 
 presence of the sinuses, which convert the body of the bone into two or more cells (5, 
 fig. 22). The compact tissue prevails in the lesser and the greater wings, and in the 
 pterygoid processes, the thick part only of these containing spongy substance. 
 
 Development. — In the foetus, as we have already mentioned, the sphenoid is divided 
 into two quite distinct parts: 1. An anterior sphenoid, consisting of the lesser wings 
 and the portion of the body which supports them ; and, 2. A posterior sphenoid, formed 
 of the great wings and the part of the body which corresponds to the sella turcica. 
 
 1. The anterior sphenoid is developed from four points of ossification; two for the 
 body, and two for the alae minores.* 
 
 2. The posterior sphenoid is also developed from four points ; two for the body, and 
 two for the great wings. 
 
 Besides these eight points, there are two others on each side ; one for the internal 
 plate of the pterygoid process, and one for the sphenoidal turbinated bone ; so that the 
 whole number of centres of ossification of the sphenoid is twelve. 
 
 The osseous points of the great wings are the first to appear ; they are visible from 
 the fortieth to the forty-fifth day ; a short time afterward, those of the lesser wings, 
 which are situated on the outside of the optic foramen. At the end of the second month 
 the osseous points of the body of the posterior sphenoid are distinct ; at the end of the 
 third month, those of the body of the anterior sphenoid, and the internal pterygoid plates : 
 the sphenoidal turbinated bones begin to ossify, according to Beclard, in the seventh 
 month of intra-uterine life ; according to Bertin, in the second year after birth. 
 
 The two points of the body of the posterior sphenoid are united from the third to the 
 fourth month ; the great wings are joined to the body in the course of five or six months 
 after birth. The two points of the body of the anterior sphenoid are joined to those of 
 the small wings about the third or fourth month ; they then unite together in the me- 
 dian plane from about the eighth to the ninth month. The union of ttie internal ptery- 
 goid plates takes place during the sixth month, t The anterior and posterior sphenoid 
 are united from the eighth to the ninth month. The sphenoidal turbinated bones are 
 not joined to the body of the bone until from the fifteenth to the eighteenth year. The other 
 changes which the sphenoid afterward undergoes are connected with the development of 
 the sinuses. It is united with the occipital bone from the eighteenth to the twenty-fifth year. 
 
 * According to Albinns, the anttnor spheaoid is formed exclusively by the union of tho osseous points of 
 the lesser wings in the median line. B6clard observes, that the process takes place sometimes as descnbed 
 by Albinus, but that occasionally there is a median point ; and that at other times there are two points for each 
 of the smaller wings, the internal of wliich forms the base of the process, and the inner half of the optic fora- 
 men; and the external forms, the remainder of the wing. These are the two points which I conceive to form 
 the body of the anterior sphenoid. The very numerous osseous points which some anatomists have described 
 are nothing more than irregular grains, which have been mistaken for constant centres of ossification. 
 
 t In the lower animals the two sphenoid bones remain separate during the whole ot life. The inner plate 
 of the pterygoid process is also a distinct bone. 
 
40 OSTEOLOGY. 
 
 The Ethmoid Bone (figs. 15 and 16). 
 
 The ethmoid is so named from the Greek word r/Ofibc, a sieve, because it is perfoj-ated 
 with a number of foramina ; it is placed in the anterior and middle part of the base of 
 the cranium, but belongs rather to the face and nasal fossse. It is included between the 
 median notch of the orbital part of the frontal and the sphenoid. It is a symmetrical 
 bone of a cuboidal figure, consisting of three parts— a middle part or cribrifmm plate, and 
 two lateral masses. 
 
 Cribriform Plate. — This is a lamina situated on the median line, horizon- 
 tal, quadrilateral, and pierced with numerous foramina. It has two surfa- 
 ces, and two borders. On the superior surface (« a, fig. 15) we observe in 
 the middle a vertical triangular process, the crista galli (i and n, fig. 22) ; 
 the summit of this eminence gives attachment to the fabc cerebri ; the an- 
 terior border terminates in front in two small processes {alee) (/), which 
 articulate with the frontal bone, and often complete the foramen caecum ; 
 the posterior border is very oblique, and is continued to the posterior edge 
 of the cribriform plate by a marked thickening. There are many varia- 
 tions in the size and direction of this process : it is frequently deflected to 
 one side.* On each side is the ethmoidal groove (a), deeper and narrower in front than 
 behind ; it is pierced throughout its whole extent with numerous foramina, which have 
 been very accurately described by Scarpa, and which form two rows ; the internal, sit- 
 uated along the base of the crista galli, being the largest. They all transmit filaments 
 of the olfactory nerves ; they are funnel-shaped, and are the orifices of canals, which 
 subdivide in traversing the cribriform plate, and terminate in grooves, either upon the 
 turbinated bones or the perpendicular plate of the ethmoid. Among these openings is 
 one which has the form of a longitudinal fissure by the side of the crista galli, and trans- 
 mits the ethmoidal or nasal branch of the ophthalmic nerve. 
 
 The inferior surface of the cribriform plate (fig. 16) forms part of the roof of the nasal 
 
 Fig. 16. fossa; ; it presents on the median line a vertical plate {g g,fig. 16), which 
 
 ' y' passes from before backward, and divides it into two equal parts. This 
 
 is the perpendicular plate of the ethmoid, continuous with the base of the 
 
 crista gaUi, quadrilateral, often deflected to one side, and forms part of the 
 
 septum narium (1, 2, 3, ^,fig. 22) : in front, it articulates with the nasal 
 
 spine of the frontal bone, and with the proper bones of the nose ; behind, 
 
 with the anterior crest of the sphenoid ; below, with the vomer, and the 
 
 cartilage of the septum ; and above it is united to the cribriform plate, 
 
 along the line of the crista galli, which appears to grow out of it. The 
 
 anterior border of the cribriform plate articulates with the frontal. The 
 
 posterior is usually notched for the reception of the spine, or process (/, 
 
 figs. 13 and 14), which surmounts the median ridge of the sphenoid. 
 
 The lateral masses are cuboid in figure, and formed of large irregular cells, which to- 
 gether are named the labyrinth. They have six surfaces : in the superior surface we ob- 
 serve several imperfect cells {d d,fig. 15), which, in the united state, are completed, and, 
 as it were, roofed in by those we have already described as existing on each side of the 
 ethmoidal notch of the frontal. We find, also, two or three grooves, which join with 
 similar grooves in the frontal bone, and form the internal orbitary canals. On the infe- 
 rior surface we perceive thin, irregularly-twisted laminae, which narrow the opening of 
 the maxillary sinuses. The most considerable of these has received the name of unci- 
 form or great process of the ethmoid : it is a curved plate which arises from the inferior 
 surface of the transverse septa, which close the anterior ethmoidal cells, and is placed 
 between the anterior extremity of the middle turbinated bone and the os planum or la- 
 mina papyracea, to be afterward described ; it sometimes articulates with the inferior 
 turbinated bone. The anterior surface presents half cells, which are covered by the os 
 unguis and the ascending process of the maxillary bone. On the posterior surface we see 
 the posterior extremities of the superior and middle turbinated bones, and of the superior 
 and middle meatus, and a convex, uneven surface, which corresponds with the posterior 
 ethmoidal cells. This surface articulates with the sphenoid above, and with the palate 
 bone below. The external surface is formed by a smooth, quadrilateral plate {e,fig. 15), 
 placed vertically and very thin, to which the ancients gave the name of lamina papyracea 
 or os planum. It has an elongated, rectangular form, is slightly curved upon itself, and 
 constitutes a great part of the internal wall of the orbit. The superior border articu- 
 lates with the frontal, and assists in forming the orifice of the internal orbital canals : 
 the inferior articulates with the maxiUary and palate bones, the anterior with the os un- 
 guis, and the posterior with the sphenoid and palate bones. 
 
 The internal surface of the lateral masses constitutes the greatest part of the external 
 wall of the nasal fossae : on it we observe, in front, a rough, quadrilateral surface, marked 
 
 * Morgagni mentions the case of an asthmatic subject, in whom the crista galli was so obliquely placed, 
 that the ethmoidal groove on one side was very much contracted, and considerably enlarged on the othet 
 There was a much greater number of foramina on one side than on the other. 
 
PARIETAL BONES. 41 
 
 by grooves and canals, which lodge the ramifications of the olfactory nerve ; behind, two 
 thin plates, twisted upon themselves like certain shells : they are the turbinated or spongy 
 bones of the ethmoid, or concha of the ethmoid. The superior {b, fig. 35) is the smaller, 
 and is sometimes named concha of Morgagni ; Bertin has seen it double. The inferior 
 {cfig. 37) is larger, and forms the middle concha ; it articulates by its posterior extremity 
 with the palate bone, and its superior border is continuous with a transverse septum, 
 which stretches across to the lower edge of the os planum, and partially closes the mid- 
 «lle or frontal cells. The superior and middle turbinated bones are separated by a hori- 
 zontal groove called the superior meaius of the nasal fossae (between b and c, fig. 37), at 
 the superior part pf which appears an opening of communication with the posterior eth- 
 moidal cells. Below the middle turbinated bone is a similar groove (between c and d, 
 fig. 37) running from before backward, and forming part of the middle meatus of the nose. 
 Anteriorly it leads into a cell, the lower part of which is broad and the upper narrow, 
 whence it has received the name of infundibulum. This cell communicates directly 
 with the frontal sinuses, and, by a small aperture, with the anterior ethmoidal cells. 
 
 Internal Structure. — ^The ethmoid is composed of extremely thin and fragile plates, ar- 
 ranged in more or less irregular cells, having a hexahedral, pentahedral, or tetrahedral 
 shape. They are disposed in distinct series, which have no communication with each 
 other. The anterior cells are the largest and most numerous ; they open into the mid- 
 dle meatus by the infundibulum ; the posterior'open into the superior meatus. There 
 is a little spongy substance in the crista galli, which is even sometimes hollowed into a 
 small sinus which communicates with the frontal sinuses. There is also spongy sub- 
 stance in the turbinated bones, and here, by a remarkable exception, it occupies the 
 surface. The specific lightness of the ethmoid is such that it floats in water, and its ex- 
 treme brittleness is readily explained by its spongy structure. 
 
 Connexions. — The ethmoid is connected with thirteen bones : the frontal, the sphe- 
 noid, the ossa unguis, the superior maxillary, the inferior turbinated, the nasal, the pal- 
 ate bones, and the vomer. 
 
 Development. — The ossification of the ethmoid does not conmience until the fifth 
 month. It begins in the lateral masses, and more particularly in the os planum ; shortly 
 afterward the spongy bones make their appearance. The middle portion is not ossified 
 until after birth. The crista galli and the contiguous part of the perpendicular plate, and 
 the cribriform plate, become bony between the sixth month and the first year. At the 
 end of the first year, the cribriform plate is united to the lateral masses. In the foetus, 
 at the full time, the lateral masses are so little developed, that their internal and exter- 
 nal walls are almost contiguous. The cells are completely formed about the fourth or 
 fifth year. 
 
 The Parietal Bones {figs. 17 and 18). 
 
 The parietal bones are so called because they form the greatest part of the s'aes oi 
 the head. They are two in number, the right and the 
 left ; but sometimes in the adult they are united so as 
 to form only one bone. They occupy the summit and 
 sides of the head. In shape they are quadrilateral, and 
 much thicker above than below, so that a force applied u^,^ 
 to the crown of the head often causes a fracture of the \i~^ 
 lower parts of these bones. The parietal bones have J' 
 two faces, four borders, and four angles. ^^^ 
 
 The external or cutaneous surface (fig. 17) is convex '- 
 and smooth, with a projection in the centre, the parietal 
 protuberance (j), which is more prominent in the child 
 than in the adult, and corresponds with the point where 
 the breadth of the cranium is greatest. Below this 
 there is a semicircular line (g), with the concavity looking downward, which forms the 
 superior boundary of the temporal fossas, and gives attachment to the temporal aponeu- 
 rosis ; the rest of the surface below this curved line gives attachment to the fibres of the 
 temporal muscle. The rest of this surface is covered only by the cranial aponeurosis 
 and the skin. 
 
 The internal or encephalic surface {fig. 18) is concave, and marked with mammillary 
 projections and digital impressions ; it is traversed by ramified ^ooves, resembling the 
 veins of a leaf {ff, fig. 18), which converge partly to the anterior inferior, and partly to 
 the posterior inferior angle of the bone, and correspond to the branches of the menin- 
 geal artery. The parietal fossa, a concavity corresponding to the prominence of the same 
 name, is situated in the middle of this surface. 
 
 The superior or sagittal border ( a b,fig. 17 and 18) is the longest : it is thick and den- 
 ticiUated, and, by its union with the opposite bone, forms the sagittal suture. On its in- 
 ternal surface there is a furrow along its whole extent, which, with that in the oppo- 
 site bone, forms the groove for the longitudinal sinus. Near this border is sometimes 
 
 F 
 
OSTEOLOGY. 
 
 found a foramen (c) {foramen parietalc), of very varia- 
 ble dimensions, which opens into the posterior part of 
 the groove, and transmits a vein which is sometimes 
 very large. We may farther state, that along this sur- 
 face the impressions made by the pacchionian glands 
 are to be observed. They are more remarkable in the 
 old than young subject. 
 
 The inferior or temporal border {d e) is the shortest : 
 it is concave, thin, and very obliquely cut on the out- 
 side, so as to resemble a scale with, radiated furrows ; 
 hence its name {margo squamosus) : it articulates with 
 the squamous portion of the temporal bone. 
 
 The anterior or frontal border {b e) is less thick and 
 less deeply indented than the occipital edge : it is bev- 
 elled externally above, and internally below, so as to articulate with the frontal bone, 
 which presents a precisely opposite arrangement. 
 
 The posterior or occipital border (a d) is very deeply indented, and articulates with the 
 superior border of the occipital by the lambdoid suture. Of the four angles, the two supe- 
 rior are right angles ; of the inferior, the anterior or sphenoidal (e) is acute, and rendered 
 very thin by the sloping of the anterior and inferior edges of the bone. Inside this angle 
 is situated the principal furrow, or sometimes canal, which lodges the middle meningeal 
 artery and veins : surgeons, therefore, recommend this angle to be avoided in perfonning 
 the operation of trepanning. The posterior or mastoid angle (d) is, as it were, truncated, 
 and is received mto the retreating angle formed by the union of the mastoid and squa- 
 mous portions of the temporal bone. Internally, it is grooved for the reception of part 
 of the lateral sinus (e, fig. 22). 
 
 Connexions. — Tlie parietal is articulated with five bones : the frontal, the occipital, the 
 temporal, the sphenoid, and the opposite parietal Above, it is separated from the skin 
 by the cranial aponeurosis only, and consequently it exposes a large extent of surface 
 to the action of external agents : hence fractures of this bone are very common, and 
 they are, more frequently than other fractures, accompanied by effusions of blood, on 
 account of the connexion with the middle meningeal artery and vein. 
 
 The internal structure is quite similar to that of the frontal. In that bone we find 
 venous canals traversing long tracts in the substance of the diploe. 
 
 Development. — The parietal bone is developed from one point of ossification alone, 
 which appears in the situation of the protuberance. Its firet traces are observed about 
 the forty-fifth day. The angles are the last parts of the bone which are developed : their 
 absence gives rise to the fontanelles of the cranium. 
 
 The Temporal Bones [jigs. 19 and 20). 
 
 The temporal bones are so called from being situated in the locality of the temples. 
 
 They are two in number, and occupy part of the sides and base of the cranium, below 
 
 the parietal bones, above the inferior maxillary, in front of the occipital, and behind the 
 
 sphenoid. The temporal bone contains the complicated apparatus of the organ of hearing. 
 
 Its figure is veiy irregular, and therefore, in order to facilitate the description, we shall 
 
 consider it as divided into three parts, the squamous, the mastoid, and the petrous portions. 
 
 Squamous portion. — The squamous portion has the form of a semicircular scale (a b c, 
 
 Jigs. 19 and 20), bearing a considerable resemblance to 
 
 one of the valves of certain shell-fish : it occupies the 
 
 anterior and superior part of the bone. It is by far the 
 
 thinnest part of the cranium ; and hence the common 
 
 but well-founded notion of the danger of blows upon 
 
 the temple, although this danger is much lessened by 
 
 the presence of the zygomatic arch and the temporal 
 
 ^^ muscle. 
 
 The external surface (/, fig. 19) forms part of the 
 temporal fossa : it is smooth, convex, and marked by 
 vascular furrows. At its lower portion is situated the 
 zygomatic process (m n) {^evyvvu, I join), so called be- 
 cause it unites the sides of the cranium to the face : it 
 is also named a-iisa capitis, and is one of the longest 
 processes of the skeleton. At its origin it is broad and directed outward ; it then grad- 
 ually diminishes in size, and bends so as to turn horizontally forward and a little out- 
 ward : it is flattened from without inward. The external surface is convex, and may 
 be easily traced under the skin ; the internal surface is concave ; the superior border, 
 which gives attachment to the aponeurosis of the temporal muscle, convex and thin ; 
 the inferior, which gives origin to the meisseter muscle, concave, thick, and much shorter ; 
 and the extremity (m) is cut from below upward and forward, and denticulated for attach 
 ment Avith a corresponding surface on the malar bone. The base of this process is 
 
TEMPORAL BONES. 43 
 
 grooved above, and serves as a julley for the reflection of piart of the temporal muscle. 
 Posteriorly, it separates into two portions or roots : the inferior (o) of these is the larger ; 
 it is transverse, covered with cartilage, and bounds the glenoid cavity in front, serving 
 also to increase the articular surface in the joint of the lower jaw. The superior (?i) is 
 longitudinal or antero-posterior in its direction : it also is bifurcated, one branch directed 
 upward, and forming part of the temporal semicircular line, the other passing between 
 the auditory meatus and the glenoid cavity. At the point of junction of the two roots 
 there is a tubercle, which gives insertion to the external lateraUigament of the lower jaw. 
 Between the two roots we observe the glenoid cavity (behind flitaivided into two portions ; 
 the anterior of which is articular, smoothjand in the fresh state covered with cartilage ; 
 the posterior (s) does not enter into the fOTfflation of the joint. The parts are separated 
 by a fissure, called glenoidal fissure, or fissure of Glasserius (before s), which transmits the 
 corda tyrapani nerve,* the laxator %mpani or external muscle of the malleus, the inter- 
 nal auditory vessels, and lodges the processus gracilis of the malleus {process of Raw). 
 
 The internal surface of the squamous portion (g, fig. 20) presents a concavity propor- 
 tionally greater than the convexity on the outside : it is 
 marked by the ordinary inequalities, and is generally trav- 
 ersed, towards the upper part, by a horizontal vascular fur- 
 row, running from before backward. 
 
 The circumference (a h c) forms about three fourths of a cir- 
 cle ; it is very obliquely cut internally in its two posterior 
 thirds, which unite with the parietal ; the anterior third is 
 thicker, and bevelled externally : it unites with the sphenoid. 
 
 Mastoid Portion (c e d,figs. 19 and 20). — ^The mastoid por- 
 tion is very prominent in adults, but only slightly developed 
 in young subjects : it occupies the posterior and inferior 
 part of the bone. 
 
 The external surface {fig. 19) is convex and rough, ter- 
 minating below and in front in a nipple-shaped process, the 
 mastoid process (e). Inside of this is a deep gi'oove called digastric (fossa digastrica), 
 because it gives origin to the muscle of that name. Behind the mastoid process we observe 
 the mastoid foramen, an opening which transmits the mastoid artery and vein, but which 
 is subject to numerous varieties in its size and position. Above the process is a rough 
 surface, for muscular attachments of the splenius and sterno-cleido mastoideus muscles. 
 
 The internal surface is concave, and forms part of the lateral and posterior fossae of the 
 cranium ; we observe on this surface a deep and broad semi-cylindrical groove {h i, fig. 
 20), which lodges the greater portion of the lateral sinus. At the bottom of this gi'oove 
 the mastoid foramen opens by one or more apertures. There is generally a considerable 
 difTerence in size between the grooves on the right and left side of the head. 
 
 The circumference, very thick and indented, unites in front with the circumference of 
 the squamous portion, forming a retiring angle (c), which is occupied by the posterior 
 inferior angle of the parietal bone, and then curves round in a semicircle to join the 
 occipital bone by means of a thick, uneven edge. 
 
 Petrous Portion ; Rocher or Pyramid {ci dv, fig. 20) Petrous Process. — This part of the 
 bone is placed between the squamous and mastoid portion, resembling a pyramid, pro- 
 jecting forward and inward into the cavity of the cranium. Its name sufficiently indi- 
 cates the extreme hardness of its osseous structure : a circumstance very important in 
 relation to its functions (for this part of the bone serves as the receptacle of the vibratory 
 apparatus of the ear), and at the same time is calculated to explain the frequency of frac- 
 tures in this situation. It has the form of a truncated pyramid with three faces, separated 
 by three borders. 
 
 The inferior surface, which is seen at the base of the cranium, is very irregular, and 
 presents the following objects, in an order from without inward: 1. A long, slender 
 process (k), generally from twelve to fifteen lines, sometimes two inches in length. 
 This process, which hcis been denominated styloid, is, in man, usually continuous with 
 the rest of the bone, but occasionally it is articulated by a movable joint, as in the lower 
 animals, where it is always separate, and is known by the name of styloid hone. 
 
 2. Behind this process, between it and the mastoid, is a sort of fossa, at the bottom 
 of which we find, besides one or two accessory foramina, the stylo-mastoid foramen (y, fig- 
 21), which forms the inferior aperture of a canal improperly called the aqueduct of Folio- 
 pius,i which transmits the facial nerve. 3. Inside of the styloid process and the stylo- 
 mastoid foramen is a triangular surface called the jugular, which joins with a correspond- 
 ing part of the occipital bone. 4. A little within and behind the styloid process is a deep 
 depression, which forms part of the jugular fossa, and lodges the enlarged commence- 
 ment or sinus of the jugular vein. 5. The inferior orifice of the carotid canal (», fig. 21), 
 Which is directed at first vertically, then horizontally, nmning forward and inward, and 
 
 * [The corda tympani, according to the author, passes through a special orifice by the side of the glenoid 
 fissure. See description of the ear, in/rd.] 
 i [Fallopius knew that this canal transmitted a nerve; he named it aqueduct merely on account of its direction.] 
 
44 OSTEOLOGY. 
 
 again vertically at its termination in the cavity of the cranium. 6. A rough surface, 
 which gives attachment to the levator palati muscle. Lastly, in front of the styloid 
 process is an osseous lamma, in the form of a vertical crest {s,fig. 19), a continuation of 
 the plate which forms both the inferior portion of the auditory canal, and the posterior 
 portion of the glenoid cavity, which it completes. This crest, which has been described 
 by authors under the name of vaginal process, because it surrounds the styloid process 
 without adhering to it, extends inward to form part of the carotid canal, and outward to 
 the mastoid process. 
 
 The other two surfaces^ the petrous portion, of which one is superior and the other 
 posterior, are in the interior of the cranium. 
 
 The superior surface, which looks forward, has a furrow running from before backward 
 and from below upward, terminating about llie middle of the surface in a small iiTcgular 
 opening, the hiatus Fallopii, which communicates "^jith the aqueduct of Fallopiu^. The 
 furrow and the hiatus contain the superior or cranial filament of the vidian nerve, and a 
 small artery. 
 
 The posterior surface shows a canal directed obliquely from within outward and for- 
 ward. This is the internal auditory meatus {I, fig. 20) ; it is shorter than the external, 
 and is terminated by a lamina divided into two parts by a transverse ridge ; in the supe- 
 rior of these parts there is a single orifice, the commencemnet of the aqueduct of Fallopius, 
 which receives the facial nerve ; the inferior is perforated by numerous openings, through 
 which the fibres of the auditory nerve pass ; it is the cribriform plate of the auditory 
 nerve. Behind the internal auditory meatus is a small opening, which is the orifice of 
 a canal named aqueductus vestibuli. 
 
 These surfaces of the petrous process are separated by three borders. 
 
 On the superior border (m v) we observe a furrow for the superior petrosal sinus ; cdso 
 a projection which corresponds with the superior semicircular canal of the internal ear, 
 and which is most prominent in the young subject ; inside of this projection, a cavity, 
 the depth of which is in the inverse ratio of the age, and is gradually obliterated in the 
 adult, and near the summit a depression, on which the fifth or trifacial nerve rests. 
 
 The anterior or sphenoidal border, in the external half of its extent, is connected with 
 the squamous portion of the bone ; at first by a suture which often remains perfect even 
 in adult life, and subsequently in a great measure disappears, but is never completely 
 obliterated. The internal half is free, and forms, by its union with the squamous portion, 
 a retiring angle, at the apex of which are the openings of two canals, placed parallel, 
 like the barrels of a double-barrelled gun, and separated by a small osseous lamina. The 
 superior canal, much the smaller, contains the internal muscle of the malleus ; the in- 
 ferior canal forms the osseous portion of the Eustachian tube. They both communicate 
 with the cavity of the tympanum ; the bony lamella, which separates them, is called the 
 cochleariform process. 
 
 The inferior, posterior, or occipital border, rough, but without indentations, is united to 
 the occipital bone by juxtaposition. It has a deep notch, which forms part of ihe fora- 
 men lacerum posterius. This notch, which is continuous with the jugular fossa, already 
 described, is frequently divided into two portions by a tongue of bone, one being anterior, 
 the other posterior. Immediately in front of the notch is a small triangular opening, 
 the inferior orifice of the aqueduct of the cochlea. 
 
 On the base (fig. 19), which is not distinct from the rest of the bone, the only part to 
 be noticed is the external auditory meatus {y), which is situated behind the glenoid cavity. 
 It is rough infeiiorly for the insertion of the cartilage of the ear ; and the canal, which 
 is more contracted in the middle than at either extremity, takes a curved direction, the 
 concavity looking downward and forward : it is chiefly formed by a curved plate, named 
 the auditory process, which constitutes the posterior half of the glenoid cavity. 
 
 The summit of the pars petrosa (», fig. 20) is very irregular and truncated : it presents 
 the superior orifice of a carotid canal,, and forms part of the foramen lacerum anterius. 
 
 Connexions. — The temporal articulates with five bones, viz., three of the cranium, the 
 parietal, occipital, and sphenoid ; and two of the face, the malar and the inferior maxil- 
 lary ; we might add, also, the os hyoides, which is attached by a ligament to the styloid 
 process. 
 
 Internal Structure. — The squamous portion is compact throughout, excepting towards 
 the circumference, where traces of diploe may be seen. The petrous portion is still 
 more compact and hard, resembling in density the teeth, or certain ivory-like exostoses. 
 The mastoid portion is hollowed out into large cells, and is very liable to be affected by 
 caries. In the description of the orga7i of hearing we shall notice the cavities which ex- 
 ist in the petrous portion ; the nervous and vascular canals will be described with the 
 nerves and vessels which traverse them. (For the aqueduct of Fallopius, see the de- 
 scription of the Facial Nerve.) 
 
 Development. — The temporal bone is developed from five points of ossification : the 
 squamous, petrous, and mastoid portions, the auditory canal, and the styloid process, 
 being each distinct. The first osseous point which appears is situated in the squamous 
 portion, and is visible towards the end of the second month. Immediately afterward 
 
THE CRANIUM IN GENERAL.. 45 
 
 tho petrous portion exhibits a bony nucleus, stretching from its base towards its apex. 
 The third point in order is that of the circle of the tympanum, a kind of ring channelled 
 all round for the membrana tympani. This circle, at first almost horizontal, becomes 
 gradually more and more oblique ; it is incomplete above, and the two extremities which 
 are applied to the squamous portion cross each other instead of uniting. In many ani- 
 mals the ring of the tympanum constitutes a distinct bone, named the lym-panic heme. 
 The fourth point of ossification appears in the mastoid portion during the fifth month. 
 The last which becomes visible is that of the styloid process : it also remains distinct 
 throughout life in the lower animals, and is called, the styloid lone. It is not uncommon 
 to find it in the same condition in the human subj'ect. 
 
 The development of these five pieces does not advance with equal rapidity. The 
 petrous portion is most quickly completed. The mastoid, squamous, and petrous por- 
 tions become united during the first year. The styloid process is attached to the rest 
 of the bone at the age of two or three years ; at birth, the glenoid cavity is almost flat, 
 on account of the absence of the auditory canal, and the slight development of the trans- 
 verse root of the zygomatic process. The ulterior changes which take place in the 
 temporal bone depend on the completion of the auditory canal and glenoid cavity, the 
 increasing size of the mastoid process, and the obliteration of the projections and filling 
 up of the hollows on the surface of the petrous portion. 
 
 It is worthy of remark, that traces of the union of the base of the petrous portion 
 with the squamous and mastoid portions, are visible in individuals of the most advan- 
 ced age. 
 
 The Cranium in general. 
 
 The different bones which we have described unite in forming the cranium, an osse- 
 ous cavity which encloses the brain, the cerebellum, and the annular protuberance. It 
 is situated above the face, is the most elevated portion of the skeleton, and forms a con- 
 tinuation of the vertebral column. "The form of the cranium is that of an ovoid, flatten- 
 ed below and at the sides, and with the large extremity turned backward. It is never 
 perfectly synametrical ; but a very great deviation has always appeared to me coincident 
 with disease of the brain. From attentive examination of a great number of sculls of 
 idiots and maniacs, I have observed that in these subjects there is a remarkable differ- 
 ence between the two sides. 
 
 The dimensions of the cranium have been very accurately determined by Bichat. The 
 antero-posterior diameter, measured from the foramen caecum to the occipital protuber- 
 ance, is about five inches ;* the transverse diameter, measured between the base of the 
 petrous portions of the temporal bones, is four inches and a half ; the vertical diameter, 
 extending from the anterior edge of the foramen magnum to the middle of the sagittal 
 suture, is rather less than the transverse. In front, and behind the spot where the 
 height and breadth of the cranium are measured, i. e., in front and behind the bases of 
 the petrous bones, the diameters progressively diminish. Hence it follows, that the 
 point where the cranium has the greatest capacity is the junction of the two anterior 
 thirds with the posterior third ; that is to say, at the place of meeting, or, if I may use 
 the expression, at the confluence of the brain, cerebellum, and spinal marrow. 
 
 The cranium, however, presents many varieties, both in regard to its dimensions and 
 shape. The varieties of form of the scull in different individuals appear generally to de- 
 pend upon the preponderance of one diameter over another ; and it may be remarked, 
 that in these cases, where one diameter is much increased, the others are almost in- 
 variably diminished in the same proportion, so that the absolute difference in size is by 
 no means considerable. 
 
 There are also variations in size and figure peculiar to the crania of different nations, 
 as has been shown by the researches of Blumenbach and Scemmerring. In the white, 
 or Caucasian race, the cranium is decidedly much larger than in the others, more es- 
 pecially than in the negro. Among certain tribes, the configuration of the cranium is 
 determined by the permanent or frequently-repeated compressions to which the sculls 
 of infants are subjected. It varies also according to age and sex, being proportionally 
 larger in the foetus than in the adult, and in the male than in the female. It should be 
 remarked that all these varieties are exclusively confined to the vault of the cavity. 
 Since the cranium is exactly moulded upon the brain, great interest has been attached 
 to the exact appreciation of its dimensions, and hence the different measurements which 
 have been adopted for this purpose. The oldest is the one proposed by Camper, under 
 the name of the facial angle. This angle is intended to measure the relative proportions 
 of the cranium and face. It is taken by drawing one line from the middle incisors of 
 the upper jaw along the front of the forehead, and another from the same point to the 
 auditory meatus. The angle included between these lines is in the European from 80" 
 -0 SS*, in the Mongolian race 75°, and in the negro, 70°. This anatomical fact had not 
 escaped the attention of the ancients. We observe that in the statues of their heroes 
 
 * [An old Paris inch is =1.065765 inch English ] 
 
40'- OSTEOLOGY. 
 
 and gods they have even exaggerated the facial angle, which is generally 90°, and even 
 more in the case of Jupiter Tonans. 
 
 The facial angle gives no information respecting the capacity of the posterior regions 
 of the cranium, and, consequently, Daubenton had this specially in view in his mode of 
 measurement, which bears the name of the occipital angle of Daubenton. This, however, 
 like the preceding, and, in fact, all linear measurements applied to the determination of 
 the capacity of the scull, is necessarily inexact. The variable thickness of the walls of 
 the cavity, the greater or less development of the sinuses, and the projection of the al- 
 veoh, or their obliteration after loss of the teeth, are all important elements in the esti- 
 mate, which have been entirely neglected ; and, moreover, the facial and the occipital 
 angle can only express the dimensions in one direction. The capacity of a cavity, hke 
 the volume of a solid, can only be determined by an estimate of its three dimensions. 
 Hence, measures of surface, and measurements taken in the interior of the cranium, 
 must be employed for this purpose. Tliis is the object proposed by Cuvier, in comparing 
 the area of the cranium and the area of the face, cut vertically from before backward. 
 
 A section of the cranium represents an oval, with the broad end backward : a section 
 of the face is triangular. In the European, the area of the cranium equals four times 
 that of the face, without the lower jaw ; in the negro, the area of the face is increased 
 one fifth. The most general result which can be deduced from a comparison of the cra- 
 nimn and face in man and in mammaUa, is that they are developed in an inverse ratio. 
 One appears to augment at the expense of the other. 
 
 Division of the Cranium, and Description of its different Regions. 
 The cranium, considered as one piece, presents an external surface, and an internal, or 
 encephalic surface. Many of the objects seen on these surfaces have been already de- 
 scribed with the particular bones to which they belong ; these we shall merely point 
 out : others, which result from the union of the bones in one conunon whole, will be ex- 
 amined more in detail. 
 
 External Surface of the Cranium. 
 The external surface of the cranium offers for consideration a superior region or 
 vault, an inferior, and two lateral regions. 
 
 The superior region or vault is bounded by a circular line, passing from the middle, 
 frontal, or nasal protuberance {glabella), along the temporal fossa, to the external occipi- 
 tal protuberance. It is principally covered by the occipito-frontalis muscle, and presents 
 in the median line, 1, the trace of the union of the two primitive halves of the frontal 
 bone ; 2, the bi-parietal or sagittal suture (sagitta, an arroic), which forms a right angle, 
 in front, with the fronto-parietal or coronal suture, and terminates behind at the superior 
 angle of the occipito-parietal or lambdoidal suture (from the Greek letter lambda). 
 
 On each side we observe three eminences, more or less prominent in different indi- 
 viduals, and always most marked in the young. These are the frontal, the parietal, and 
 the superior occipital protuberances. Between the frontal and parietal protuberances, 
 the coronal suture is situated ; and between the parietal and the occipital, we find the 
 lambdoid suture. Besides these, there are a great number of smaller projections, which 
 Gall has also denominated protuberances, and to which much importance is attached in 
 his system. 
 
 The inferior region or base of the cranium {fig. 21) is flattened and very irregular. It is 
 p- 21 bounded, behind, by the external occipital protuberance 
 
 (a) and superior semicircular line {a b) ; in front, by 
 the glabella, or nasal eminence ; laterally, by a line 
 passing over the mastoid and external orbital process- 
 es. I shall content myself by describing in this place 
 the posterior half of the base of the cranium ; the 
 other half wiU be included in the description of the 
 face, with the bones of which it concurs in forming 
 the orbital, nasal, and zygomatic fossaj. The ptery- 
 goid processes below, and the posterior edge of the 
 sphenoid above, define the limits of these two portions. 
 The posterior half of the base of the cranium pre- 
 sents, in the median line, and in an order from behind 
 forward, the external occipital protuberance {a), the 
 external occipital crest {a c), the foramen magnum 
 (d), and condyles (c), the basilar process («)> ^^^ the 
 transverse suture, which results from the articulation 
 of the body of the sphenoid with the truncated inferior 
 angle of the occipital bone, the spheno-occipital suture. 
 On each side we observe the inferior occipital pro- 
 tuberances, presenting certain variations in size in 
 different subjects, to which Gall has attached great 
 importance in his craniological system. These pro 
 
THE CRANIUM IN GENERAL. 47 
 
 tuberances are bounded above by the superior semicircular line of the occipital bone (J); 
 they are crossed in the middle by the inferior semicircular Une {g), which is separated 
 from the preceding by muscular impressions. Between the inferior semicircular line 
 and the occipital foramen are also a number of inequalities for the attachment of mus- 
 cular fibres. Still more anteriorly is the posterior condyloid fossa, and occasionally the 
 posterior condyloid foramen {g). Outside the condyles are the jugular surface (t), the 
 eminence of the same name, and the petro-occipital suture, running obliquely from behind 
 forward and inward (i k), without any indentations, or even complete juxtaposition of 
 the bones, and terminating behind in a large irregular opening (before i), the foramen 
 lacerum postcrius, which is divided into two parts by a tongue of bone : the anterior is 
 the smaller, and transmits the eighth pair of nerves ; the posterior is larger, and is call- 
 ed the jugular fossa, from its receiving the enlarged commencement {sinus or diverticu- 
 lum) of the jugular vein. The petro-occipital suture terminates in front in another irreg- 
 ularly triangular opening, the foramen lacerum. anterius (k), which is closed by cartilage, 
 and forms, in fact, a fontanelle between the edges of the occipital, temporal, and sphe- 
 noid bones. In front of the petro-occipital suture is the inferior surface of the petrous 
 bone, with its numerous asperities ; then, still proceeding from behind forward, we find 
 the mastoid process (Z), the digastric groove (m), the stylo-mastoid foramen (7), the sty- 
 loid and vaginal processes, the inferior orifice of the carotid canal (»), and the petro-sphe- 
 noidal suture, at the external termination of which the osseous portion of the Eustachian 
 tube opens by an orifice directed obliquely for\vard and downward. 
 
 Thus all the sutures of the posterior half of the base of the cranium meet in the fora- 
 men lacerum anterius. From its internal angle, the spheno-occipital suture stretches 
 across to the same part of the opposite foramen. The petro-sphenoidal suture sets out 
 from the external angle, and becomes continuous with the fissure of Glasserius ; and 
 the petro-occipital suture extends from the posterior angle to the occipito-mastoid suture, 
 which it joins at an obtuse angle : all these sutures are formed by juxtaposition, and not 
 by mutual reception, as those of the roof of the scull. 
 
 The lateral regions of the cranium are bounded, behind, by the lambdoid suture ; in front, 
 by the external orbital process ; and above, by the temporal ridge. This region, more or 
 less rounded in different subjects, is, nevertheless, the flattest part of the vault of the 
 scull. Proceeding from behind forward, we observe, 1, the mastoid region, comprehend- 
 ing the mastoid foramen (9, Jig. 21), the external auditory meatus, the glenoid cavity, 
 and the transverse root of the zygomatic process ; 2, the temporal region or fos&a, con- 
 cave in front, convex behind, bounded below by the zygomatic arch, which projects con- 
 siderably from the head, more especially in carnivorous animals, and by a ridge which 
 separates it from the zygomatic fossa. The temporal fossa is traversed by numerous 
 sutures, arranged in the following manner : The fronto-parietal or coronal suture (c b. Jig. 
 22) descends vertically ; from its inferior extremity two others proceed, one in front, the 
 sphe no-frontal, the other behind, the sphcno-parietal. Each of these soon divides into two 
 branches. From the spheno-parietal the spheno-temporal descends, and terminates in 
 the fissure of Glasserius ; the temporo-parietal (b i d) passes horizontally, and becomes 
 continuous with the lambdoidal suture {df). The spheno-temporal and temporo-parie- 
 tal sutures are, each, part of the squamous suturk. From the spheno-frontal suture the 
 two following proceed : the fronto-jugal,* running horizontally, and the spheno-jugal, 
 which passes downward ; the denominations of these sutures indicate at once the bones 
 by which they are formed. The explanation which we have given appears the most 
 Ukely to facilitate the recollection of these numerous sutures, by connecting them with 
 each other. The following table exliibits a summary of all that has been stated : 
 
 I^Spheno-frontaJ { gpheno-jugal. 
 
 All these sutures are remarkable, from the circumstance that the bones which enter 
 into their formation are cut obliquely like scales, and for the most part the edge of the 
 bone above is overlapped by the edge of the bone below, so that each inferior scale, like 
 the abutment of an arch, prevents the superior one which corresponds to it from being 
 forced outward. (Vide Mechanism of the Cranium. Sy\desmology.) 
 
 Internal Surface of the Cranium. 
 
 In order to examine the internal surface of the cranium, it is necessary to make two 
 sections, one horizontally from the occipital protuberance to the glabella {Jig. 23), the 
 other vertically along the median line from before backward {Jig. 22). 
 
 In the median line, proceeding from before backward, we observe the frontal crest or ridge, 
 and the longitudinal groove, stretching from the frontal crest, along the roof of the scull to 
 the internal occipital protuberance. In this groove, which is of no great depth, we find aline 
 which indicates the place of union of the two pieces of the frontal hone during the earJy 
 
 ♦ Tho malar bone is often called the jvigal bone, and hence the names of fronto-jugal and spheno-jugaL 
 
OSTEOLOGY. 
 
 Fig. 23. 
 
 Fig. 22. periods of life, and the internal surface of the 
 
 sagittal suture. It receives the superior longi- 
 tudinal sinus in its entire extent, and contains 
 the internal orifices of the parietal foramina. 
 
 On each side are the frontal fossae, correspond- 
 ing to the protuberances of the same name, 
 and the internal surface of the fronto-parietal 
 (coronal) suture {be, Jig. 22); the encephalic 
 surface of the parietal bone (^i dfc), and the 
 parietal fossa; the lambdoid suture {df), and 
 the superior occipital fossa. We may remark 
 that the fossce are deeper than would "seem to 
 be indicated by the external prominences, be 
 cause they are partly formed at the expense of 
 the bone itself; and that the sutures are less 
 deeply denticulated on their internal than on their external aspect. 
 
 Lastly, the whole internal surface of the vault of the cranium, but especially that of 
 the parietal bones, is traversed by ramified grooves (i i), partly for veins, partly for ar- 
 teries ; the venous grooves, which are not perceptible in all subjects, but which are very 
 large in some, are distinguished from the arterial, as M. Breschet has pointed out, by 
 their being perforated by numerous foramina. 
 
 The base of the cranium {fig. 23), presents three series of fossae, or three regions, ar- 
 ranged, as it were, in steps upon an inclined plane, from before backward, and from above 
 downward. They are described as the anterior, middle, and posterior regions. 
 
 Anteriw or cthmoido-frontal region. In this region we observe, in the middle, the eth- 
 moidal fossa, in which is the foramen caecum ; tl^e 
 crista gaUi (a) ; the ethmoidal grooves, and the for- 
 amina with which they are perforated ; the ethmoi 
 dal fissure, for the ethmoidal or nasal branch of the 
 ophthalmic nerve ; the ethmoido-frontal sutures, run- 
 ning from before backward ; the orifices of the inter- 
 nal orbitary foramina ; and the trace of the ethnw-sphe- 
 noidal suture, running transversely. Behind the eth- 
 moidal fossa, the surface of the sphenoid is slightly 
 impressed by the passage forward of the olfactory 
 nerves. 
 
 Laterally, we see the orbital plates {b), remarkable 
 for the prominence of their mammillary projections, 
 and traversed by small grooves for the ramifications 
 of the middle meningeal artery ; and the fronto-sfhe- 
 Twidal sutures (before c), which mark the union of the 
 lesser wings of the sphenoid (c), with the orbital por- 
 tion of the frontal bone {b). The orbital plates sup- 
 port the anterior lobes of the brain. 
 
 The middle region exhibits in the centre a fossa, in 
 which we observe the depression for the olfactory 
 nerves, the optic groove, and olivary process (before 
 d) ; the pituitary fossa (d), deeply excavated behind ; the quadrilateral plate (behind d) ; 
 the cavernous grooves ; and the anterior and posterior clinoid processes. On the sides 
 we find very deep fossae, which correspond with the middle lobes of the brain, called 
 middle lateral fossa of the base of the cranium; they are broad externally, narrow inter- 
 nally, and are bounded in front by the posterior edge of the lesser wings of the sphenoid (c), 
 and behind by the superior border of the petrous portion of the temporal bone (/«)• They 
 are formed by the superior surface of the petrous portion, the internal surface of the squa- 
 mous portion of the temporal, and the superior surface of the great wings of the sphe- 
 noid. They present, successively from before backward, the sphenoidal fissure (or for- 
 amen lacerum orbitale) ; the foramen rotundum, or superior maxillary '(2) ; the foramen 
 ovale (3) ; the foramen spinosum (4) ; the internal orifices of the foramen lacerum an- 
 terius and carotid canal (before 5), and the hiatus Fallopii. We see here, also, the union 
 of the sphenoid with the squamous and petrous portions of the temporal bone, forming 
 the sphcno-tcmporal {i and c) and pctro-sphe?ioidal sutures. This fossa is traversed from be- 
 hind forward and outward by a groove {i 4), which commences at the foramen spinosum, 
 passes along the external border of the sphenoid, or, rather, is hollowed out from the 
 spheno-temporal suture, and divides into two branches ; the anterior, the larger, pro- 
 ceeds to the anterior inferior angle of the parietal bone, with the anterior ramified groove 
 m which it becomes continuous ; the posterior is directed horizontally backward to the 
 posterior inferior angle of the parietal bone. In some cases, the portion of the groove 
 which extends from the foramen spinosum to the summit of the lesser wing of the sphe- 
 noid, almost equals in diameter the lateral grooves, and it is then almost always pierced 
 by foramina : it contains the middle meningeal artery, and a large vein 
 
THE CEANIUM IN GENERAL. 49 
 
 Posterior region of the base of the cranium. This region presents in the middle the ba- 
 silar groove (k) ; the spheno-occipital suture, the foramen magnum (m), the anterior con- 
 dyloid foramina (8) {Ji,fig. 22), the internal occipital ridge, and protuberance {o,fig. 21). 
 Laterally, the inferior oceipital fossa, the deepest in the scull, which are formed by the 
 posterior surface of the petrous portion of the temporal bone, almost the whole of the en- 
 cephalic surface of the occipital bone, and the posterior inferior angle of the parietal. 
 We find here the foramen lacerum posterius (7), the suture which unites the temporal to 
 the occipital bone, and along the petro-occipital suture, a smedl groove named inferior pe- 
 trosal (on each side of A:), 
 
 The inferior occipital fossa is bounded above by a broad and deep groove (n), intend- 
 ed to lodge the lateral sinus, and called the lateral groove. It commences at the internal 
 occipital protuberance (o), and proceeds horizontedly outward to the base of the petrous 
 portion, where it is again enlarged, and passes roimd, extending downward and inward 
 along the occipital fossa, until it arrives at the occipito-meistoid suture (r), where it rises 
 and terminates in the foramen lacerum posterius. The inferior occipital fossa is divi- 
 ded into two parts by this groove : an anterior, formed by the posterior face of the pars 
 petrosa, and a posterior, formed by the occipital bone. In this groove, the mastoid fora- 
 men, the posterior condyloid foramen, when it exists, and the superior and inferior petrosal 
 grooves open. 
 
 The dimensions of the lateral grooves are extremely variable ; inost commonly the 
 left is smaller and shallower than the right, especially in its horizontal portion. 
 
 Of the eminences and depressions on the internal surface of the cranium, the most 
 deeply marked are those situated upon the base. This is more especially the case with 
 regard to the orbital plates and the middle and lateral fossae. Since the publication of 
 the works of Gall and Spurzheim, anatomists have re-adopted the opinion of the an- 
 cients, who regarded these eminences and depressions as corresponding respectively 
 with the anfractuosities and the convolutions of the brain : the cranium, in fact, is mould- 
 ed upon the brain ; to be convinced of which, it is only necessary to repeat the following 
 experiment, which I have often made for this purpose. Remove the brain from the 
 cavity of the cranium, and supply its place by plaster of Paris ; when dry, this substance 
 will present a faithful model of the convolutions and anfractuosities of the brain. In 
 cases of chronic hydrocephalus, where the inequalities of the brain are effaced by the 
 accumulation of fluid, the internal surface of the cranium shows scarcely any vestiges 
 of eminences and depressions. The osseous tissue, notwithstanding its hardness, is 
 easily moidded around organs, and yields with facility to the compression which soft 
 parts exercise upon it. It is very uncommon to open the cranium of a subject, some- 
 what advanced in years, without observing in some points a more or less considerable 
 absorption of the parietes of the scull, occasioned either by clusters of certain smaU 
 white bodies, called glandulae Pacchioni, or by dilated veins. 
 
 One anatomical fact worthy of notice is the want of any configuration of the external 
 surface conformable in its details with that of the internal surface : compare, for in- 
 stance, the roof of the orbit with the cranial surface of the orbital plate of the frontal 
 bone. This difference is due to the circumstance that the digital impressions encroach 
 on the diploe, and are, in part, excavated from the space otherwise occupied by it. The 
 two compact laminag which form the bones of the cranium are in some measure inde- 
 pendent of each other ; the internal one belongs, so to speak, to the brain ; the exter- 
 nal to the locomotive system. The diploe is the limit of these two laminae. This ana- 
 tomical fact is at variance with the doctrine of Gall respecting the protuberances ; it proves 
 that the cerebral convolutions are not faithfully represented by external prominences. 
 
 In order to complete the anatomical history of the cranium, it yet remains to consider, 
 1. Its general development; 2. The connexion of its several parts. (For this latter 
 subject, see Syndesmology.) 
 
 As to the analogies which have been so ingeniously established between the cranium 
 and the vertebral column, a detailed analysis of them would be out of place in an ele- 
 mentarv work like the present. 
 
 Development of the Cranium. 
 
 The cranium is remarkable for the early period at which its development commences. 
 As soon as ihe embryo is sufficiently advanced in growth to exhibit any distinction oi 
 parts, the head, under the form of an ovoid vesicle, greatly exceeds the magnitude of 
 the whole body With regard to the order in which the different parts are ossified, we 
 may remark, that the bones of the roof precede those of the base, in like manner as in 
 the vertebrae the laminae are ossified before the bodies. In both cases the evolution is 
 most prompt in those parts which are especially destined to protect import£uit organs. 
 
 Cranial Bones at Birth. 
 The bones of the roof of the scull appear before those of the base, but at birth ossifi- 
 cation is less advanced in the roof than in the base ; accordingly, in a foetus at the full 
 time, the bones of the base form a solid whole, and are immovable, while those of the 
 
 G 
 
W OSTEOLGOY. 
 
 roof are separated by membranous intervals, which permit of pretty extensive move- 
 ments, so that at this period the roof of the cranium yields, in a great degree, to pressure. 
 At birth, there is nothing resembling the mode of union called suture. Nevertheless, 
 each bone presents denticulations like the teeth of a comb round the circumference. 
 The existence of these indentations before the period when the bones come into con- 
 tact, proves that they are not the result of any mechanical action produced by their 
 meeting; the only influence of this kind to which they are subjected during their forma 
 tion, is the deviation of opposing denticulations. The frontal suture is the first developed. 
 Another peculiarity of this stage of development is the existence of those membra- 
 nous intervals denominated fontanelles. They are produced in the following manner : 
 the process of ossification commences in the centre of the bone, and advances from that 
 point to the circumference, the most distant parts of the bone being, of course, the last 
 to be ossified. These points, in broad or flat bones, are the angles, and, consequently, 
 at the place where several angles of diflferent bones ultimately unite, there must exist 
 an unossified space at this time : these spaces are the fontanelles. They have all been 
 pointed out in the description of the cranial bones ; they are of especial importance to 
 the accoucheur, on account of the indications which they furnish for determining the 
 position of the child. All traces of the fontanelles are completely obliterated at the age 
 of four years. 
 
 The Wormian Bones. 
 
 The Wormian bones should be regarded as supplementary points or centres, developed 
 when the general ossification proceeds somewhat slowly ; and we therefore consider it 
 proper to include a description of them in the account of the development of the cranium. 
 
 The Wormian bones, so called because the first description of them has been assigned 
 to Wormius, a physician in Copenhagen, are also denominated exacted bones, ossa trique- 
 tra, or complimentary bones of the scull. They are extremely variable, both in situation, 
 number, and size ; but they are most common in the lambdoid suture, i. e., in the most 
 rugged of all the sutures, the asperities of which they tend to increase. This fact 
 should not be overlooked in examining fractures of the cranium. The most remarkable 
 of all the Wormian bones is the one which sometimes supplies the place of the superior 
 angle of the occipital, and which Blasius has called the triangular bone ; it is the epactal 
 bone properly so called. It is not uncommon to find a Wormian bone in the sagittal su- 
 ture, and this may be compared to the inter-parietal bone of some animals. Bertin has 
 described a quadrangular bone occupying the situation of the anterior fontanelle, and 
 resembling it in figure : I have myself met with such a fonnation. The anterior inferior 
 angle of the parietal is sometimes formed by a Wormian bone ; I have seen one in the 
 squamous suture. 
 
 In some sculls the whole of the occipital bone above the occipital protuberance is 
 formed by these bones. Generally both tables of the bone enter into the formation of 
 the Wormian bones ; but there are instances in which they are confined to the external, 
 and others to the internal table. 
 
 The Wormian bones are not always visible in the interior of the cranium : in some 
 cases they are, as it were, incrusted in the substance of the bone, at the circumference 
 of which they are observed. 
 
 Their mode of development resembles that of the broad bones, i. c., it proceeds by ra- 
 diation from the centre to the circumference. According to Beclard, they are not devel- 
 oped until five or six months after birth : at their junction with the surrounding bones 
 they form sutures, which are the first to become effaced in after life. 
 
 From all that has been said regarding this class of bones (which are in a manner acci- 
 dental, for they are neither constant in number nor in their existence), it is evident that 
 they can be only considered as supplementary points of ossification, and not as performing 
 an important office in contributing to the solidity of the cranium, as the name cles de 
 voiUe, given to them by some anatomists, would seem to indicate. 
 
 Progress of Development in the Adult and the Aged. 
 
 The cartilaginous lamina which separates the bones at first, gradually becomes ossi- 
 fied. The sutures become so serrated that it is almost impossible to separate the bones 
 without breaking some of their teeth. At the same time that the bones increase in 
 breadth, they augment in thickness ; the diploe, which at first did not exist, is developed 
 between the two plates. In the adult, several bones already begin to join by osseous 
 union ; of this we have an example in the sphenoid and occipital, which at an early pe- 
 riod form one bone. 
 
 In the aged, the traces of the sutures are in a great measure effaced, so that in cer- 
 tain cases the whole scull would seem to be composed of one entire piece. The con- 
 tinuity of some bones is occasionally such, that the venous canals of the one communi- 
 cate and open directly into those of the other. It is not uncommon to find the bones of 
 an old subject thin and translucent like horn, in a greater or less extent. This diminu- 
 tion of thickness, added to the increasing fragility of the osseous tissue, affords an ex- 
 
SUPERIOR MAXILLARY BONES. 51 
 
 planation of the ease with which the sculls of old people may be broken : and the con- 
 tinuity of the bones explains the possibility of the fracture being much extended. 
 
 The greatest variety exists as to the thickness and density of the bones of the scull in 
 old age, Generally they are as brittle as glass, but in some instances they are so soft 
 and spongy that, although easily depressed, they can scarcely be fractured by the blow 
 of a hammer. I have frequently, in old people, seen the teeth of the parietal and lamb- 
 doidal sutures soft, placed in juxtaposition, and merely joined by a soft fibrous sub- 
 stance, which admitted of their being separated without difficulty. The lambdoidal su- 
 ture is the one which the most frequently presents this disposition, and in all the in- 
 stances of this kind which I have met with, the superior borders of the occipital overlap 
 the corresponding borders of the parietal. 
 
 The F^ce. 
 
 The face is tnat very complicated osseous structure, which is situated at the anterior 
 and inferior part of the head, and is hollowed out into deep cavities for the reception of 
 the organs of sight, smell, and taste, and for the apparatus of mastication. 
 
 The face is divided into two portions, the upper and the lower jaw. The lower jaw is 
 formed by one bone only ; the upper jaw consists of thirteen bones. But, although this 
 circumstance tends to establish a great difference between the two, yet it must be re- 
 marked, that all the parts of the upper jaw are so immovably united, that in appearance 
 they form only one bone ; and, moreover, that it is essentially formed by one fundamental 
 piece, the superior maxillary bone, to which all the others are attached as accessory parts. 
 
 Of the fourteen bones which constitute the face, two only are median or single : viz., 
 the vomer, and the inferior maxilla. All the others are double, and form six pairs, viz., 
 the superior maxillary, the malar, palate, and proper nasal bones, the ossa unguis, and 
 the inferior turbinated bones. 
 
 The Superior Maxillary Bones {figs. 24 and 25, with the Palate Bones). 
 
 They are two in number, united, to a certain extent, in the median line, and form al- 
 most the whole of the upper jaw. Their figure is very irregular : they belong to the 
 class of short bones. They have three surfaces, an external, an internal, and a superi- 
 or ; and three borders, an anterior, a posterior, and an inferior. 
 
 External or Facial Surface {fig. 24). — Proceeding from before backward, we observe a 
 small fossa in which the myrtiform muscle {depressor labii supe- 
 rioris et alee nasi) is inserted, and which is bounded externally 
 by the ridge which forms the alveolus of the canine tooth ; a 
 deeper fossa, named fossa canina, or infra orhitalis, surmounted 
 by the orifice of the infra orbitary canal (o) ; and, more posteri- 
 orly, a vertical ridge, which separates the fossa canina from the 
 maxillary tuberosity (m). This protuberance, which is most 
 prominent before the appearance of the wisdom tooth, is trav- 
 ersed by small canals, the posterior and superior dental, which 
 transmit vessels and nerves of the same name. From the an- 
 terior part of this region, a long vertical process arises, the as- 
 cending or nasal process {a b) of the superior maxilla. It is of a pyramidal shape, and flat- 
 tened. Its external surface is smooth, and presents the openings of certain vascular ca- 
 nals which communicate with the interior of the nasal fossae, and some inequalities for 
 the insertion of the common elevator of the upper lip and ala of the nose. On the inter- 
 nal surface {fig. 25) we observe, in succession from above downward, a rough surface, 
 which assists in closing the anterior cells of the ethmoid ; a horizontal ridge, to which 
 the middle turbinated bone is attached ; a concave surface, which forms part of the mid- 
 dle meatus of the nose ; and another horizontal ridge for articulation with the inferior 
 turbinated bone : like the external, this surface also is perforated by foramina, and mark- 
 ed by arterial furrows. Its anteriw edge {a b,figs. 24, 25) thin, and bevelled internally, i& 
 applied to the nasal bone. The posterior edge is thick, and marked by the lachrymo-nasal 
 g'oove, which forms part of the lachrymal groove above, and of the nasal duct below. It 
 has two edges or lips : the internal, which is very thin, articulates with the os unguis 
 and the inferior turbinated bone ; the external, which is rounded, gives attachment to 
 the straight tendon and some fibres of the orbicularis palpebrarum muscle. The direc- 
 tion of the lachrymo-nasal groove is slightly curved ; the convexity being internal and 
 in front, the concavity external and behind. The summit of the nasal process is trun- 
 cated and serrated for articulation with the nasal notch of the frontal bone. 
 
 Superior or Orbital Surface {c,fig. 24). — This is the smallest of the three surfaces. It 
 forms almost the entire floor of the orbit : it is triangular, and slightly oblique from within 
 outward, and from above downward, and presents a groove behind, which is continuous 
 with the infra-orbitary canal. This last-named passage, at first a mere channel, after- 
 ward a complete canal, passes from behind forward and inward, bends down and opens 
 at the upper part of the canine fossa. Before its termination, it gives off a small canal, 
 the anterior and superior dental, which runs in the anterior wall of the maxiUary sinus, 
 
53 OSTEOLOGY. 
 
 and transmits the vessels and nerves which are distributed to the incisor and canine 
 teeth. Sometimes this branch of the canal opens into the maxillary sinus. In many 
 subjects I have seen it curve backward, and conduct a communicating branch between 
 the infra-orbitary and palatine nerves as far as the maxillary tuberosity. The orbiial 
 surface is bounded by an external edge, which forms part of the spheno-maxillary fissure ; 
 by an internal edge, which articulates with the os unguis, the os planum of the ethmoid, and 
 the palate bone ; and by an anterior edge, which forms part of the rim of the orbit. At 
 the external termination of this edge is a very irregular eminence, appearing as if part of 
 the bone had been broken off: this is the malar process, which corresponds with the sum- 
 mit of the maxillary sinus, and is articulated with the malar bone. At the internal ex- 
 tremity of the orbital edge, we find the ascending process already described. 
 
 Internal or Naso-palatine Surface {Jig. 25). — This surface is divided into two unequal 
 parts by a horizontal square plate, which intersects it at right 
 angles. This plate is the palatine process {t), the superior surface 
 of which, smooth and hollow, is broader posteriorly than anteri- 
 orly, and forms part of the floor of the nasal fossae : its inferior 
 surface is rough, and forms part of the roof of the palate : its 
 internal border (t) is very thick in front, and articulates with 
 the corresponding edge of the opposite bone. This border is 
 surmounted by a crest, which contributes to form the furrow 
 into which the vomer is received, and which presents, at the 
 junction of its anterior with the two posterior thirds, a groove 
 (r) running obliquely upward and backward. This groove, when 
 united with a similar one on the opposite bone, forms the anterior palatine or incisive ca- 
 nal, which is single below and double above. The anterior edge of the palatine process 
 is very narrow, and forms part of the anterior opening of the nasal fossae : the posterior 
 edge, bevelled at the expense of the superior table, supports the horizontal portion of the 
 palate bone. 
 
 That part (to) of the internal surface of the maxillary bone which is situated below 
 the palatine process, is of no great extent : it forms part of the arch of the palate. A 
 furrow more or less deep, and bounded by projecting edges, runs along the external bor- 
 der of the palatine process, and protects the posterior palatine vessels and nerves. The 
 raucous membrane of the palate covers this region of the bone. The part of the inter- 
 nal surface (n) of the superior maxillary bone which is above the palatine process, be- 
 longs to the nasal fossa : it is covered by the pituitary membrane. We observe here 
 from before backward, 1, the internal surface (c) of the ascending process (a) ; 2, below 
 the inferior ridge, a smooth surface which forms part of the inferior meatus of the nose ; 
 3, the inferior orifice (behind c) of the lachrymo-nasal groove, sometimes converted into 
 a complete canal by a bridge of bone ; 4, the opening of the maxillary sinus (s), which 
 appears wide in a detached bone, but in its natural connexion is contracted by prolonga- 
 tions of the palate bone, the ethmoid, the inferior turbinated bone, and the os unguis, all 
 of which are articulated with the circumference of this opening ; it is still farther dimin- 
 ished when the bones are covered by their pituitary membrane. At its lower part, this 
 orifice presents a fissure in which a lamina belonging to the palate bone is received : this 
 method of articulation has received the name of Schindylesis. At the upper part are 
 small cells, which unite with the ethmoid ; behind the orifice is a rough surface, which 
 articulates with the palate bone ; and, lastly, a groove, which forms part of the posterior 
 palatine canal. 
 
 The orifice which we have just described leads into the interior of a cavity denom- 
 inated maxillary sinus, or antrum of Highmore, although it had been before very accurate- 
 ly described by Vesalius. It is hollowed out from the substance of the maxillary bone, 
 and has the form of a pyramid, the base of which corresponds with the internal surface 
 of the bone ; the summit with the malar process ; the superior wall with the floor of the 
 ojbit ; the anterior wall with the fossa carina, and the posterior with the maxillary tuber- 
 osity. These two last-mentioned walls are traversed by linear projections or ridges, 
 which correspond with the anterior and posterior dental canals. There is also one ridge 
 upon the superior wall : it indicates the passage of the infra-orbitary canal. The ex- 
 treme tenuity of this superior or orbitary wall is an anatomical fact of great importance, 
 because it explains the influence which tumours developed in the sinus exert upon the 
 organs contained in the cavity of the orbit. The septum between the sinus and the bot- 
 tom of the alveoli is also so thin, that an instrument can easily penetrate into the sinus 
 in this situation. This remark applies particularly to the alveolus of the canine tooth. 
 
 The anterior harder {g a, figs. 24 and 25) of the superior maxilla presents, below, a ver- 
 tical portion (g- d), surmounted by a small eminence called the nasal spine (a) : it is then 
 hollowed out into a deep notch (a h), to form half the anterior orifice of the nasal fossae ; 
 and, lastly, becomes continuous with the anterior edge (h a) of the ascending process. 
 The posterior harder is vertical and very thick : it articulates below with the pterygoid 
 process, through the medium of the palate-bone : above, it forms part of the pteiygo- 
 maxillary fissure. • 
 
PALATE BONES. 53 
 
 The inferior or alveolar border {g k) is the thickest and strongest part, being, in some 
 respects, the base of the bone. It is hollowed into conical cavities separated by thin 
 septa. These cavities are the alveoli or sockets of the teeth : they are proportioned in 
 dimensions to the size of the fangs vi^hich they are intended to lodge, and in like man- 
 ner are subdivided into two, three, or four secondary cavities. The bottom of these al- 
 veoU is in apposition with the maxillary sinus, into which they occasionally open. This 
 border presents, especiaUy in front, flutings or projections which correspond with the 
 alveoli, and depressions which mark the inter-alveolar septa. 
 
 In young subjects we may observe, chiefly behind the incisor teeth, some very remark- 
 able foramina, to which much importance has been attached as connected with the phe- 
 nomena of dentition. 
 
 Internal Structure. — This bone is remarkably light for its size, on account of the larg« 
 cavity which it encloses. It is more compact than most of the short bones, and has spongy 
 tissue only in the alveolar border, the maxillary tuberosity, and the malar eminence. 
 
 Connexions. — The superior maxilla is articulated with two bones of the cranium, the 
 frontal and the ethmoid, and with all the bones of the face. It lodges eight of the teeth 
 of the upper jaw. 
 
 Development. — Anatomists are not at all agreed respecting the number and arrange- 
 ment of the osseous points which concur in forming the superior maxilla. 
 
 In the maxillary bone of the fcetus, and sometimes even in that of the adult, there are, 
 as I can attest from observation, two very remarkable fissures, which would seem to in- 
 dicate the primitive separation of the bone into three pieces. 
 
 1. The first fissure, which may be called the incisive fissure, is visible on each side of 
 the arch of the palate. It commences at the septum, which divides the alveoli of the 
 canine tooth and lateral incisor, is continued backward to the anterior palatine canal, 
 and is prolonged above on the internal surface of the ascending process. This fissure 
 is apparent only on the internal surface of the superior maxilla : it either does not exist 
 at all upon the external surface, or is so early obliterated that it can scarcely ever be 
 met with. The portion of the maxilla circumscribed by this fissure sustains the incisor 
 teeth, and represents the incisor or inter-maxillary bone of the lower animals. In hare- 
 lip, the solution of continuity is in the situation of this fissure. It is therefore probable 
 that this anterior portion of the maxillary bone is developed from a special point. Bertin 
 asserts this, and Meckel and Beclard admit it. I have not been able to observe such 
 independent development at any period of foetal life at which I have examined the max- 
 illary bone. 
 
 2. A second and equally constant fissure is visible in the situation of the infra-orbital 
 canal, and is prolonged from the edge of the orbit in the form of a small suture to the 
 anterior orifice of this canal : it may be called the orbital fissure. This fissure, like the 
 preceding, has always seemed to me incomplete, and not occasioned by the separation 
 of a distinct piece. 
 
 The superior maxillary bone is one of the earliest in making its appearance. Ossifi- 
 cation commences in it from the thirtieth to the thirty-fifth day, in the situation of the 
 alveolar arch. 
 
 At birth the superior maxilla has little height, but a considerable extent from before 
 backward. At this period it is chiefly formed by the alveolar border, which is almost con- 
 tiguous to the floor of the orbit. The maxillary sinus is already very apparent. In the 
 adult, the vertical dimensions increase by enlargement of the sinus. In the aged, the al- 
 veolar process becomes flattened, and diminished in height. 
 
 The Palate Bones (Jigs. 24, 25, 26, and 27). 
 
 The palate bones are situated at the posterior part of the nasal fossae and the palatine 
 arch ; they are two in number, sjrmmetrical, and each pig. 26. Fig. ar. 
 
 composed of two thin quadrilateral laminae, one of which 
 is horizontal, the other vertical, and which are joined to- 
 gether at right angles. 
 
 The horizcmtal plate {b c, figs. 26 and 27), the only one 
 known to the ancients, and named by them the as quad- 
 ratum, presents a superior surface (jif), smooth and con- 
 
 tinuous with the floor of the nasal fossae, of which it forms 
 the broadest part : an inferior surface {b c), which com- 
 pletes the arch of the palate : it is rough, slightly concave 
 in front, and presents behind and to the outside a trans- 
 verse ridge for the insertion of the tensor palati muscle ; 
 and in front of this ridge is the inferior orifice of the pos- 
 terior palatine canal. The anterior edge of this plate is cut obliquely, so as to rest upon 
 the posterior edge of the palatine process of the superior maxillary. The posterior edge 
 is concave, and very thin ; it gives attachment to the velum palati. The internal edge 
 is sunnounted by a crest, which forms one of the sides of the vomer, and terminates be 
 aind by a sharp process (d), which, when united to the corresponding part of the opposite 
 
M OSTEOLOGY. 
 
 bone, constitutes the posterior nasal spine, which gives attachment to the levator muscle 
 of the uvula (azygos uvulae). The external edge is united to the vertical portion of the bone. 
 
 The vertical portion, or lamina (a b), is slightly inclined inward, quadrilateral, longer, 
 broader, and thinner than the preceding. On it we observe, 1. An internal surface (mf 
 and 2, fig. 25), which contributes to form the external wall of the nasal fossae, and which 
 presents from above downward a horizontal ridge for articulation with the middle tur- 
 binated bone ; a groove belonging to the middle meatus ; another ridge for articulation 
 with the inferior turbinated bone (e and 2, fig. 25) ; and another groove which makes 
 part of the inferior meatus (e/and l,fig. 25). 2. An external surface (s b,fig. 26, and p 
 b, fig. 27), very irregular, which contributes to form the bottom of the zygomatic fossa 
 above, and which is rough in front for union with the superior maxillary. This surface 
 is traversed by a vertical groove, which, by itself, forms £dmost the entire extent of the 
 posterior palatine canal {g g, fig. 26). 3. An anterior or maxillary border {i, fig. 27), very 
 thin and irregular, which advances so far forward as to contract the entrance into the 
 maxillary sinus, and presents a tongue of bone, which is received into the fissure already 
 described as existing at this orifice. 4. A posterior or pterygoid border {I, fig. 26), which 
 is applied to the inner plate of the pterygoid process. There is below, at the angle form- 
 ed by its union with the posterior edge of the horizontal portion, a very considerable pro- 
 cess for the size of the bone : this has been called palatine process, or tuberosity of the os 
 palati (3, fig. 25 ; lb, fig. 26), but is better named pterygoid or pyramidal process : its base 
 is continuous with the test of the bone, and from this point passes downward, and is, as 
 it were, enclosed in the bifurcation of the pterygoid process of the sphenoid. Its upper 
 surface is traversed by three grooves, the middle of which forms part of the pterygoid 
 fossa, and the lateral ones are rough, and receive the simimits of the two pterygoid plates. 
 Below, the pyreunidal process exhibits the orifices of the accessory ducts of the posterior 
 palatine canal. Externally it presents a rough surface, which articulates above with the 
 tuberosity of the superior maxilla, and which is free in the rest of its extent, and forms 
 part of the zygomatic fossa. The middle of this process is grooved in a vertical direc- 
 tion, for the posterior palatine canal. 5. The inferior border of the vertical portion is 
 continuous with the external edge of the horizontal plate. 6. The superior or sphenmdal 
 border is connected with the sphenoid in almost the whole of its extent. It presents a 
 deep notch, forming three fourths or sometimes the entire spheno-palatine foramen {G,fig. 
 25 ; 0, figs. 26, 27 ; n, fig. 37), which corresponds with the spheno-palatine ganglion, and 
 gives passage to the vessels and nerves of the same name. This border is surmounted 
 by two processes, an anterior or orbital (4, fig. 25 ; a, figs. 26, 27), and a posterior or sphe- 
 noidal {5, fig. 25 ; m,figs. 26, 27). The sphenoidal process is the broader, particularly at 
 its base, but is not so elevated as the anterior : it presents three facettes — an internal, 
 which forms part of the nasal fossa ; an external, which is visible in the zygomatic fossa ; 
 and a superior, which articulates with the sphenoid, and presents a groove, which con- 
 tributes to form the ptcrygo-palatine canal. 
 
 The orbital process, inclined outward, and supported by a constricted portion or neck, has 
 five facettes. Three of these are articular, viz., the internal {n,fig. 27), which is concave, and 
 unites with the ethmoid, covering and completing its cells ; the anterior {p, fig. 27), which 
 joins the maxillary bone ; and the posterior (q, fig. 26), which is united to the sphenoid by 
 certain asperities surrounding a cell, which exists in the substance of the process, and com- 
 municates with the sphenoidal sinus. The other tico are non-articular, viz., the superior (r, 
 fig. 26), which forms the deepest part of the floor of the orbit, and the external (s, fig. 26), 
 which forms part of the zygomatic fossa, and is separated from the preceding by ,a small 
 edge, which constitutes a portion of the spheno-maxillary fissure. 
 
 Internal Structure. — The palate bone is compact throughout, excepting in the palatine 
 process, where it is thick and cellular. 
 
 Connexions. — The palate bone articulates with its fellow on the opposite side, with the 
 maxillary, the sphenoid, the ethmoid, the inferior turbinated bone, and the vomer. 
 
 Development. — This bone is developed from a single point of ossification, which ap- 
 pears from the fortieth to the fiftieth day, at the point of union of the vertical and hori- 
 zontal portions, and the pyramidal process. During its development, the bone appears 
 as it were crushed down, so that the vertical portion is shorter than the horizontal, and 
 there is a marked predominance in the antero-posterior diameter. This disposition is 
 in accordance with the shortness of the vertical diameter of the superior maxilla. 
 
 ^s-^- The Malar Bones {fig. 28). 
 
 The malar hones, called also cheek, jugal, or zygomatic bones, are 
 situated in the superior and lateral part of the face : their form is 
 that of a very irregular four-sided figure. They have thn e sur- 
 faces, an anterior, a posterior, and a superior ; four borders, and 
 four angles. 
 
 The anterior or cutaneous surface (a) looks outward, is convex 
 and smooth, and presents the openings of several foramina {h). 
 
NASAL BONES. 55 
 
 named malar, which are intended for nerves and vessels. This surface gives attach- 
 ment below to the zygomaticus major muscle. It forms the most prominent part of the 
 cheek, and is covered only by the skin and orbicularis palpebrarum muscle : it is, conse- 
 quently, much exposed to injury. 
 
 The superior or orbital surface (jb) is supported by a thick curved process, the orbital pro- 
 cess, which arises from the bone almost at a right angle. This surface is concave, and 
 of small extent : it forms part of the orbit, exhibits the internal openings of one or more 
 malar foramina, and terminates behind by a rough, serrated edge, which articulates 
 above with the frontal and sphenoid bone, and below with the superior maxillary. The 
 same maxiUary edge presents in the middle a retiring, smooth angle, which constitutes 
 the anterior extremity of the spheno maxillary fissure. 
 
 The posterior or temporal surface is concave, and presents a smooth surface Ijehind, which 
 contributes to form the temporal fossa, and on which one or more malar foramina open ; 
 and a rough surface in front, which unites with the malar process of the superior maxilla. 
 
 Of the /our borders, two are superior ; of these, the anterior or orbital {d e) is semi-lunar, 
 rounded and blunt, and forms the external third of the base of the orbit ; the posterior 
 or temporal {e f) is thin, and curved like the letter S, and bounds the temporal fossa in 
 front. Of the two inferior borders, the anterior or maxillary (d g) is very rough and 
 articulates with the maxillary bone ; the posterior or masseteric (gf) is horizontal, thick, 
 and tubercular, and gives attachment to the masseter muscle. 
 
 Of the/oMr angles, the superior ox frontal (e), which is much elongated, and vertical, is 
 the tliickest part of the bone, and articulates with the external angular process of the 
 frontal bone : the posterior or zygomatic (/), broader and thinner than the preceding, is 
 serrated, and slants downward and backward, for articulation with the zygomatic process 
 of the temporal bone, which rests upon it. The internal or orbital angle {d) looks in- 
 ward and forward, is very acute, and articulates with the superior maxillary near the 
 infra-orbitary canal. The inferior or malar angle {g) looks downward, is obtuse, and 
 unites with the outer part of the malar or jugal process of the superior maxillary. 
 
 Internal Structure. — Tlie malar bone is almost entirely compact, possessing spongy 
 tissue only in the anterior and inferior edge, and in the part where the orbital portion is 
 given off. It is constantly traversed by a canal called zygomatic. This passeige is gen- 
 erally simple, but sometimes double or even multiple, and opens by at least three orifices. 
 The superior or orbital orifice is visible on the surface of the same name ; the next or 
 external zygomatic foramen is on the cutaneous surface of the bone ; and the third or 
 internal zygomatic on the inner surface of the vertical portion. 
 
 Connexions. — The malar bone is articulated with the superior maxillary, the frontal, 
 the sphenoid, and the temporal. 
 
 Development. — It is developed from one point of ossification, which appears about the 
 fiftieth day of fcetal life. The ulterior changes which it undergoes do not require par- 
 ticular notice. 
 
 The Masai Bones {fgs. 29, 30). 
 
 The nasal bones are two in number, asymmetrical, and very small in the human sub- 
 Fig. 29. Fig. 30. ject ; they are closely contiguous to each other, sometimes united into 
 one piece superiorly. They are situated at the upper and middle part 
 of the face, and form, as their name indicates, the osseous part of the 
 nose, of which they constitute the root. They are directed obliquely 
 downward and forward, but with various degrees of inclination in dif- 
 ferent subjects ; and hence the varieties in the shape and prominence 
 of the middle or bridge of the nose. Their figure is rectangular and 
 oblong ; they are thick and narrow above, broad and thin below ; and 
 have two surfaces, an anterior and a posterior, and four edges. 
 The anterior or cutaneous surface {fig. 29) is covered only by the skin and pyramidalis 
 nasi muscle, and hence the ease with which these bones are fractured : it is concave 
 above, flat or even convex below : the orifice of a vascular canal is always very distinctly 
 seen, which is variable in its situation, sometimes single, but often accompanied by 
 others of smaller size. 
 
 The posterior or pituitary surface (fig. 30) is concave, and forms the anterior part of the 
 roof of the nostrils : it is marked by vascular and nervous furrows, and in the fresh state 
 is covered by the pituitary membrane. 
 
 Of the four edges, the superior (a, figs. 29, 30), short, thick, and serrated, articulates 
 with the nasal notch of the frontal bone. The inferior (d), very thin, and more elonga- 
 ted, has a slight notch in the centre for the passage of a nervous filament, and forms 
 part of the anterior orifice of the nasal fossae : it unites with the lateral cartilage of the 
 nose. The internal (b) edge is thick above, and bevelled, so that, when approximated to 
 the other bone, the two constitute a fiirrow, in which the nasal spine of the frontal and 
 the perpendicular lamella of the ethmoid bone are received. The external (c) edge is some- 
 what longer than the internal, is slightly bevelled on the outer table, and indented for 
 articulation with the ascending process of the superior maxilla, which rests upon it. 
 
66 . OSTEOLOGY. 
 
 Connexions. — The two bones are articulated together : they unite also with the frontal, 
 the ethmoid, and the superior maxiUa, and likewise with the lateral cartilages cf the 
 nose : they afford passage to the vessels which establish a communication between the 
 skin of the nose, and the mucous membrane of the nasal fossae. 
 
 Internal Structure. — The nasal bones are thick and cellular in their upper parts, thin 
 dnd entirely compact in their lower, and are traversed by nervous and vascular grooves. 
 
 Development. — The nasal bone is developed from one single osseous point, which ap- 
 pears before the end of the second month. 
 
 Ossa Unguis^ or Lachrymal Bones {figs. 31, 32). 
 
 These are the smallest bones of the face : they are thin, like paper, and have the trans 
 Fig. 31. Fig 32. parence, tenuity, and even the shape of a nail, from which circum- 
 stance one of their names has been derived. They are situated at 
 the internal and anterior part of the orbit : their figure is irregularly 
 . quadrilateral : they are two in number, and, therefore, asymmetri- 
 If '7r cal. They have two surfaces and four edges. 
 ' j,i#^ The external or orbital surface {fig. 32) is divided into two unequal 
 parts by a vertical ridge (a b), which terminates below in a sort of 
 '^ hook. The portion anterior to the ridge is narrow, and marked by 
 a porous groove (c), which, when joined to the channel on the ascending process of the 
 superior maxilla, forms the lachrymal groove (hence the name of lachrymal bone).* The 
 portion {d) of the os unguis, which is posterior to the ridge, completes the inner wall of 
 the orbit. 
 
 The internal or ethmoidal surface {fig. 31) presents a furrow (a' b), which corresponds 
 to the external ridge ; the portion {c') in front of the furrow forms part of the middle 
 meatus ; behind is a rough surface {d'), which covers the anterior cells of the ethmoid. 
 
 Of the four borders, the supcrior{a a) is rough, and articulates with the internal angu- 
 lar process of the frontal bone ; the inferior {b h') articulates with the inferior turbinated 
 bone by a small tongue which passes backward, and which contributes to form the nasal 
 canal, and with the internal edge of the orbital surface of the superior maxillary. The 
 anterior edge {e e') unites with the ascending process of the maxillary bone ; and the 
 ■posterior edge {f f), slightly denticulated, joins the orbital portion or lamina papyracea 
 ,^mhe ethmoid. 
 
 ^^ Connexions. — The os unguis articulates with the frontal, the ethmoid, the superior 
 maxillary, and the inferior turbinated bone : they assist in the formation of the lachrymal 
 sac, the nasal canal, and the internal wall of the orbit. 
 
 Structure. — The os unguis consists of a very thin layer of compact tissue, and is the 
 inost brittle of all the bones. It is of importance to note its tenuity and fragility, be- 
 , Hji^aase it is concerned in the operation for fistula lachrymalis. 
 
 Development. — The os unguis is ossified at the commencement of the third month, from 
 one single point. 
 
 The Inferior Turbinated or Inferior Spongy Bones (figs. 33, 34, and d, 
 
 fig- 37). 
 
 The inferior turbinated bones, so called on account of their curved figure, are situated 
 
 Figs 33 34. ^^ *^^ lower part of the external wall of the nasal fossae {d, 
 
 ' ' fig. 35), below the ethmoid, whence the name sub-ethmoidal 
 
 turbinated bones. They are two in number, asymmetrical, and 
 
 their greatest diameter is directed from before backward. 
 
 They have two surfaces, two edges, and two extremities. 
 
 The internal surface {fig. 34, and d,fig. 37) is convex, and 
 looks towards the nose, which it sometimes touches when 
 that part deviates from the straight direction ; the external sur- 
 face {fig. 33) is concave, and forms part of the middle meatus. 
 Both are rough, and, as it were, spongy, which has given rise 
 to the assertion that these bones form an exception to the general rule of the spongy 
 tissue being in the interior of bones : this appearance, however, is owing to the multi- 
 plicity of canals intended for nerves, and more particularly for the veins which expand 
 over the bone. The superior or articular edge {abed, figs. 33, 34) is very irregular, and 
 presents from before backward, 1. A thin edge {a b), which articulates with the ascend- 
 ing process df the superior maxilla. 2. A small eminence bearing the name of nasal or 
 lachrymal process (5), which articulates by its apex with the os unguis, and by its two 
 edges with the two lips of the ascending process of the superior maxillary, to complete the 
 nasal canal. 3. A curved pkte, called auricular process (e, fig. 33) by Bertin, who com- 
 pared it to the ear of a dog : this plate is directed downward, and applied partially upon 
 the orifice of the maxillary sinus, which it assists in closing. 4. Behind this process 
 
 * The existence of lachryma) bones is subordinate to that of the lachrymal secretion. The;r are not met 
 with in those animals -which bve in the water, and which have neither lachrymal glands nor ptjssages. 
 
VOMER. INFERIOR MAXILLA. 57 
 
 we find a thin edge (c d, figs. 33, 34), which articulates with a small ridge on the palate 
 bone. 5. Between the auricular and the lachrymal processes are small prominences 
 which unite with tlie ethmoid. 
 
 The inferior or free border (a d) is convex, and thicker in the middle than at its ex 
 tremities : it is separated from the floor of the nostrils by an interval (m o, fig. 37) of un- 
 certain extent, a circumstance to be remembered during the introduction of instruments 
 into the nasal fossae. 
 
 The anterior extremity (a) is a little less pointed than the posterior {d), which distin- 
 guishes the bone of the right from that of the left side. 
 
 Connexions. — The inferior turbinated bones articulate with the superior maxillary, the 
 palate bones, the ethmoid, and the ossa unguis : they have important relations with the 
 inferior orifice of the nasal canal, which they defend from the contact of foreign bodies. 
 
 Structure. — ^Their external spongy appearance depends upon the multitude of canals 
 with which their surface is furrowed, but they are almost exclusively formed of compact 
 tissue. 
 
 Development. — Their ossification commences about the fifth mftith of foetal life, by a 
 point situated in the centre. 
 
 The Vomer {jig. 35, and 10, fig. 22). 
 
 The vomer is so called from its supposed resemblance to a ploughshare. It is situated 
 in the median plane, and forms the posterior part of the sep- jVe'. 35. 
 
 tmn of the nostrils. It is thin, flat, and quadrilateral, and 
 has two surfaces and four edges. The surfaces are placed 
 laterally (as at a, fig. 35), and are generally plane, but they 
 are often bent to one side or the other, and are then convex 
 and concave in opposite directions : they are always smooth, 
 and covered by the pituitary membrane, and present small 
 vascular and nervous furrows. The superior or sphenoidal border {Jb, fig. 35, and 3, fig. 
 22) is the shortest and thickest : it is marked by a deep groove, which receives the in- 
 ferior crest of the sphenoid ; the two lips of the groove are bent outward, and received 
 into furrows on the inferior surface of the same bone, and thus complete a small chan- 
 nel for the passage of vessels and nervous filaments. The inferior or maxillary (c) bor- 
 der is the longest, and is received into the furrow which is formed by the union of the 
 two palate bones behind and of the two superior maxiUary in front : it sometimes termi- 
 nates by a more or less prominent process behind the anterior nasal spine. The anterior 
 or ethmoidal border {d, fig. 35, and 3 4, fig. 22) presents the continuation of the groove on 
 the superior edge, and receives the inferior bcujder of the perpendicular plate of the eth- 
 moid. There is no groove where it is attach" to the cartilaginous septum. The pos- 
 terior or guttural edge {e,fig. 35, and t, 10, fig. 22) is free : it is thin and sharp, and in- 
 clines downward and forward : it separates the posterior openings of the nasal fossae. 
 
 Connexions. — The vomer is articulated with the sphenoid, the ethmoid, the superior 
 maxillary, the palate bones, and the cartilage of the septum. 
 
 Internal Structure. — ^The vomer is composed of two very thin compact laminae, which 
 are distinct above, but united below. Some anatomists have called these plates alee of 
 the vomer. 
 
 Development. — It is developed from one point of ossification, which is situated at the 
 lower part of the bone, and appears before the end of the second month. It then pre- 
 sents the form of a deep groove, embracing the cartilage just as, at a future period, it 
 embraces the sphenoidal crest. At birth the vomer is still only a groove ; afterward 
 this condition is confined to the sphenoidal and ethmoidal edges of the bone. It is not 
 uninteresting to note the peculiar and uncommon manner in which the ossification pro- 
 ceeds from the surface to the interior of the cartilage. 
 
 Inferior Maxilla {fig. 36). 
 
 While, as w^ have before observed, a considerable nimiber of bones to enter into the 
 formation of the upper jaw, the lower jaw consists of one pig. 36, 
 
 bone only. The inferior maxilla occupies the lower part of 
 the face. From the number and importance of the practi- 
 cal points connected with this bone, too much attention 
 cannot be bestowed on the study of its form and connex- 
 ions. It has the shape of a parabolic curve, the two ex- 
 tremities of which, called rami, form a right angle with the 
 middle portion or body. 
 
 Of the body or middle portion (a). — The body represents a 
 curved plate, convex in front and concave behind. It of- 
 fers to our notice an anterior and a posterior surface, and a 
 superior and inferior border. The anterior surface has in 
 the middle a vertical line, called symphysis menti (c d) ; it 
 
 H 
 
9i OSTEOLOGY. 
 
 marks the place of union of the two pieces of \jfhich this bone is composed in young 
 subjects, and which, in a great number of animals, remain distinct through life.* 
 
 The mode in which the two halves of the body of the inferior maxilla are united, 
 forming an arch instead of an angle, as in other animals, constitutes one of the distinc 
 live characters of the human species ; and the vertical direction of the symphysis, com- 
 pared Avith its very oblique inclination downward and backward, or almost horizontal 
 position in the lower animals, is a no less characteristic mark of man, who alone can be 
 said to possess a chin.\ 
 
 In front the symphysis terminates by a triangular eminence called mental 'process (d). 
 Behind, it presents below four small tubercles, two superior and two inferior, known by 
 the collective appellation of genial processes {yivcLov, the chin), and give attachment to 
 the genio-hyoid and genio-glossal muscles. 
 
 On each side of the symphysis, we observe on the anterior or cutaneous surface of the 
 body of the inferior maxilla, 1. A small depression for the attachment of muscles, named 
 mental fossa (e c). 2. A line, which commences at the mental process, passes obliquely 
 upward, and becomes' continuous with the anterior edge of the ramus of the jaw : it is 
 named the external oblique, or external maxillary line (c/), and is also intended for muscu- 
 lar insertions. 3. Above this line, the mental foramen (_g), the orifice of the inferior dental 
 canal, which transmits the mental vessels and nerves. 4. The anterior surface of the 
 alveolar arch (c h), marked by a series of projections corresponding to the alveoli, and 
 separated by vertical depressions, which point out the situation of the inter-alveolar sep- 
 ta. 5. Below the external oblique line, a smooth surface (a), separated from the skin by 
 the platysma myoides muscle. 
 
 The posterior or lingual surface is in some measure moulded upon the tongue : it pre- 
 sents, 1. The mylo-hjoidcan line (k) (jivXog, dens molaris), called also internal oblique or in- 
 ternal tnaxillary, which commences at the genial processes, and passes upward and back- 
 ward, becoming more prominent opposite the last molar tooth. 2. Below this line, a 
 broad but superficial depression, which lodges the sub-maxillary gland. 3. Above the 
 oblique line, and near the symphysis, a fossa, which lodges the sub-lingual gland, and a 
 sracfoth surface covered by the mucous membrane of the mouth and gums. 
 
 These two lines, the external and internal oblique, divide the body of the inferior max- 
 illa into two parts, a superior or alveolar, and an inferior or basilar. The first named 
 constitutes almost the entire body of the bone in the foetus and the infant ; in the adult it 
 forms only two thirds of the depth of the bone, the other third being the basilar portion : last- 
 ly, in the aged, the alveolar portion almost entirely disappears, and the basilar only is left. 
 
 The superior or alveolar border describes a smaller curve than the corresponding alveo- 
 lar edge of the superior maxilla ; so that, in a regular conformation of the parts, the in- 
 ferior incisor teeth are overlapped by thgl, superior. This border is less tliick in front 
 than behind, where it projects inward : it is pierced by a series of sockets or alveoli, re- 
 sembling those of the superior maxilla, and, like them, variable according to the kind of 
 teeth which they are intended to receive. 
 
 The inferior border or base of the jaw {d m) is the thickest part of the bone ; it forms 
 part of a larger curve than the superior border, so that the jaw projects forward in some 
 measure at the lower part : this projection varies much in different subjects. 
 
 Rami of the iyiferior maxilla {b b). — These are quadrilateral, and present, 1. An external 
 surface (A) covered by the masseter muscle, which is inserted into it, especially below, 
 where we may observe depressions and ridges, and where the bone itself is more or 
 less bent outward ; in front of these ridges is a slight mark, which corresponds with the 
 situation of the facial artery. 2. An internal or pterygoid surface, also rough, for the at- 
 tachment of the internal pterygoid muscle, and on which is observed the superior orifice 
 (I) of the inferior dental canal, which is wide, and has a sort of spine, to which the in- 
 ternal lateral ligament of the temporo-maxillary articulation is attached : a small groove 
 passes from this orifice in the same direction as the canal, and bears the name of mylo- 
 hyoidean furrow, because it lodges the nerve of that name. 3. A posterior or parotid edge, 
 which is round, and gives attachment below to the stylo-maxillary ligament : it is era- 
 braced by the parotid gland. 4. An anterior edge (r), marked by a groovi^ which is the 
 continuation of the alveolar border ; the anterior and posterior lips of this groove being 
 formed by the external and internal oblique lines. 5. A superior edge, very thin, and hol- 
 lowed out into gi deep notch, called sigmoid notch (n o), on account of its shape, giving 
 peissage to nerves and vessels. 6. An inferior edge, which is nothing more than a con- 
 tinuation of the inferior border of the body of the bone. 
 
 The angle which the rami form with the body of the bone is named the angle of the 
 jaw (m). It is a right angle in the adult, but very obtuse in the infant, as also in the 
 
 * In serpents these pieces form a movable joint ; and as a similar arrangement obtains between the two 
 halves of the upper jaw, these reptiles are enabled to swallow an object much larger than their head, or even 
 than their body. 
 
 t It is interesting to remark the difference in the dissection of the symphysis in the Caucasian and Ethi- 
 opian varieties of the human family. In the former it is placed nearly vertically, slightly oblique from above 
 to below, and from behind to before. In the latter it is oblique from before to behind, and in this respect re- 
 sembles the conformation in the inferior animals, more especially in the Simiie. 
 
INFEBIOE MAXILLA. ^ 
 
 «iaruivora and some of the rodentia^ this disposition enabling its muscles to act with 
 ' greater power. 
 
 The rami of the inferior maxilla are terminated above by two processes : the anterior; 
 called the coronoid process (n) ; the posterior, named the condyle (p). 
 
 The coronoid process is triangular, and inclined forward ; broad at its base, and pointed 
 at its summit ; it gives attachment to the temporal muscle. The size of this process in 
 the different species of animals bears an exact and constant proportion, both to the depth 
 and extent of the temporal fossa, and to the strength and curvature of the zygomatic arch. 
 
 The condyle articulates with the glenoid cavity of the temporal bone ; it is an oblong 
 eminence, the greatest dizuneter of which is directed sUghtly inward and backward. It 
 is supported by a contracted portion, called the neck of the condyle {^cervix) (o). This neck 
 is turned inward in such a manner that the condyle, which it supports, does not project 
 beyond the external plane of the ramus of the jaw ; it is also pr§tty deeply excavated 
 internally, to afford attachment to the external pterygoid muscle. The neck of the con- 
 dyle is the weakest part of the inferior maxilla. 
 
 Connexions. — The inferior maxilla articidates with the temporal bone, and lodges the 
 lower range of teeth. 
 
 Structure. — The external surface of the inferior maxUla is composed of compact tis- 
 sue ; the interior of the bone assumes the form of diploe, and is traversed for a great 
 part of its extent by the dental or inferior maxillary canal, which transmits the vessels 
 and nerves that are distributed upon the teeth of this jaw. This canal commences at 
 the middle of the ramus, by a groove covered with a fibrous lamina, the only use of 
 which, as it appears to me, is to protect the vessels and nerves, and to separate them 
 from the internal pterygoid muscle. From this point it proceeds forward and inward be- 
 low the mylo-hyoidean line, the curvature of which it follows ; it gradually becomes con- 
 tracted in diameter ; and in the situation of the second smaU molar or bicuspid tooth, it 
 divides into two canals, the larger of which is very short, and opens upon the external 
 surface of the body of the bone at the mental foramen already described ; the other, very 
 minute, pursues the original track, and is lost near the middle incisor tooth. In its pas- 
 sage the inferior dental canal communicates with the alveoli, by one, and sometimes two 
 foramina, through which the vessels and nerves of the teeth are transmitted. The sit- 
 uation of the dental canal varies much in different periods of life. In the new-bom in- 
 fant, before the appearance of the teeth, it occupies the lowest portion of the jaw ; after 
 the second dentition, it corresponds pretty nearly with the mylo-hyoidean line ; and after 
 loss of the teeth, it runs along the alveolar border. In the inferior maxilla of the old 
 subject, the anterior orifice of the dental canal, or the mental foramen, is close to the su- 
 perior border of the bone. The dimensions of the dental canal are no less remarkable 
 for their variations ; it is very large in the foetus, and in the child before the appearance 
 of the second set of teeth ; it diminishes during adult age, and is much contracted in the 
 old subject. 
 
 Development. — The inferior maxilla is developed by two points of ossification, one for 
 each lateral half Antenrieth admits, in addition, three complementary points ; one for 
 the condyle, one for the coronoid process, and one for the angle ; but I have never ob- 
 served them. The case is different, however, with a point of ossification described and 
 figured by Spix, which forms the inner side of the alveolar border, or, rather, of the den- 
 tal canal. In a foetus of about fifty or sixty days, I have seen a kind of bony spiculum, 
 which passed along the internal surface of the body and ramus of the bone ; on the one 
 half of the maxillary bone this spiculum was entirely free ; but that of the other side ad- 
 hered by the internal third of its length. The spine which surmounts the dental canal 
 is nothing more than the extremity of this bony spiculum. It follows, therefore, that the 
 inferior maxilla is developed from four points of ossification. 
 
 The inferior maxilla takes precedence of all the bones of the head in its development, 
 and, indeed, of all the bones of the skeleton, excepting the clavicle. The inferior edge 
 of the body of the bone appears as early as the thirtieth or thirty-fifth day ; this extends 
 backward to form the ramus, and in front to form the portion which supports the incisor 
 teeth ; it is probable that the osseous point of the dental caned, mentioned above, appears 
 at the same time. From the fiftieth to the sixtieth day, each half of the bone appears 
 already marked by a groove common to the dental canal and the alveoli. At a later 
 period, the groove becomes very considerable, and is divided into alveoli by septa, which 
 at first are incomplete, but afterward become perfect ; the alveoli and their septa occupy 
 at this time the entire depth of the bone. 
 
 The point of ossification described by Spix is united to the rest of the bone from the 
 fiftieth to the sixtieth day. (Spix aflirms that it remains separate until the fourth 
 month.) The two halves of the maxilla are joined together during the first year after 
 birth. The traces of this union exist for some time, but are afterward effaced ; in the 
 lower animals the suture remains throughout life. 
 
 The changes which the inferior maxilla undergoes after birth, relate, 1- To the angle 
 which the ramus forms with the body of the bone, which is very obtuse at birth, and be- 
 oomes a right angle after devetopment is completed. 2. To the alterations effected in 
 
60 OSTEOLOGY. 
 
 the booy of the bone, by the first and second dentitions, the loss of teeth in liie aged, 
 and the subsequent absorption and disappearance of the alveoli. 
 
 The Face in general. 
 
 The fourteen bones which we have described, united to each other, and joined to the 
 bones of the cranium, form a piece of bony sculpture, symmetrical, extremely complica- 
 ted, destined to lodge the organs of smell, sight, and taste, and to be the instrument of 
 mastication. This bony sculpture forms the face, which is situated below the cranium, 
 above the neck, and in front of the vertebral column, from which it is separated by the 
 pharynx, and is bounded on each side by the zygomatic arches. 
 
 Dimensions of the Face. 
 
 In order to form a just idea of the dimensions of the face, it is necessary to examine 
 a scull cut vertically from before backward (as in fig. 22). We then perceive that the 
 face is comprised within a triangular space, which is bounded above by an irregular line 
 that separates it from the cranium ; in front by the face, properly so called ; and below, 
 by a line passing below the symphysis menti. If a line be drawn above the inferior 
 maxilla, and under the arch of the palate, when prolonged backward, it will be in the 
 plane of the foramen magnum ; for the cranium having much less depth in front than 
 behind, a horizontal line, which touches the cranium behind, is separated from it in front 
 by the entire height of the upper jaw. 
 
 The vertical diameter, which extends from the frontal protuberance to the chin, is the 
 longest of all the diameters of the face. It gradually diminishes from before backward. 
 The transverse diameter is of considerable extent in the situation of the cheeks, but di- 
 minishes above and below this point. The antero-posterior diameter stretches above from 
 the nasal spine to the basilar process ; below it is greatly contracted ; and at the level 
 of the chin only measures the thickness of the symphysis. 
 
 With regard to the dimensions of the face as a whole, we shall only refer to what has 
 been already stated concerning the inverse proportion of the area of the cranium, and 
 that of the face, in different species of animals.* 
 
 The face represents a triangular pyramid, and offers for consideration three surfaces 
 or regions : an anterior, a superior, and an inferior. 
 
 Anterior or Facial Region. 
 
 The numerous anatomical differences which this region presents form distinctive 
 characters, not only of different nations, but also of different individuals. 
 
 It is bounded above by the forehead, below by the base of the inferior maxilla, and 
 laterally by a line which passes along the external angular process, the malar bone, and 
 the ridge which separates the canine fossa from the tuberosity of the maxilla. In this 
 region we observe, in the median line, the nasal eminence ; a transverse suture, formed 
 by the union of the proper nasal bones with the os frontis, the fronto-nasal suture ; below 
 this suture, the nose, a pyramidal eminence, narrow above or at its root, broad below or 
 at its base, and formed by two bones, which are united together by juxtaposition in the 
 median hne, and externally to the ascending process of the superior maxilla. Below 
 this eminence is the anterior orifice of the nasal fossa, which has the form of a heart on 
 playing cards, and presents at the bottom the anterior nasal spine, and below this a ver- 
 tical suture, the maxillary, the interval which separates the middle incisor teeth, the 
 opening of the mouth, and the symphysis menti. On each side, we find the opening or 
 base of the orbit, directed obliquely outward, of an irregular square form, and presenting 
 above the supra-orlitary foramen ; below, the infra-orhitary foramen ; on the outside, the 
 fronto-jugal suture ; and, on the inside, the fronto-maxillary suture. Below the opening 
 of the orbit is the canine fossa, then the alveoli and teeth of the two jaws, the extemsd 
 oblique line, the mental foramen, and the base of the inferior maxilla. 
 
 Superior or Cranial Region. 
 This region is so united with the inferior surface of the cranium, that the scull and 
 the superior maxilla form only one piece, and cannot be removed from each other. It 
 presents, in the median line, counting from behind forward, the articulation of the vomer 
 with the sphenoid, in which articulation there is a mutual reception of parts, the sphe- 
 noidal crest being received between the laminae of the vomer, and these, in their turn, 
 being lodged in corresponding fissures in the sphenoid ; the articulation of the vomer 
 with the posterior edge of the perpendicular plate of the ethmoid ; the articulation of 
 this perpendicular plate with the nasal spine of the frontal bone ; and the articulation of 
 this spine with the proper bones of the nose. On each side, proceeding from within out- 
 ward, we observe, 1. The roof of the nasal fossae, formed behind by the inferior surface 
 of the body of the sphenoid ; in the middle by tlie cribriform plate of the ethmoid ; and 
 in front by the pusterior surface of the nasal bones. 2. More externally, the base of the 
 
 ' Vide of the cranium in general ; of the facial angle of Camper ; the occipital angle of Danbenton, and the 
 measurement of Cuvier, p. 45 
 
THE FACE IN GENERAL. 01 
 
 pterygoid processes, the articulation of the palate bone with the sphenom, the pterygo- 
 palatine canal, and the spheno-palatine foramen. 3. The articulation of the lateral mass- 
 es of the ethmoid with the sphenoid behind, and with the frontal bone in front. 4. The 
 articulation of the internal angular process of the frontal bone with the os unguis. 5. The 
 articulation of the nasal notch of the frontal bone with the ascending process of the su- 
 perior maxilla, and the proper bones of the nose. 6. More externally still, the roof of the 
 orbit, bounded externally by the articulation of the frontal with the malar bone and the 
 sphenoid, and by the sphenoidal fissure. 7. The anterior surface of the great wing of 
 ^ the sphenoid, which forms the largest portion of the external wall of the orbit ; 8. Out- 
 side the orbit, the zygomatic arch. 
 
 Inferior or Guttural Region. 
 
 This region forms part of the pharynx and cavity of the mouth. It presents from be- 
 hind forward, 1. A vertical portion; 2. A horizontal portion ; and, 3. Another vertical 
 portion. 
 
 The vertical portion {fig. 21) exhibits in the median line the posterior edge of the sep- 
 tum narium, formed by the vomer ; the posterior extremity of the articulation of the vo- 
 mer with the sphenoid (o, fig. 21) ; and the posterior nasal spine. On each side, the pos- 
 terior opening of the nasal fossa {k o, y), which is quadrilateral, longer in its vertical than 
 in its transverse diameter, and formed internally by the vomer, externally by the ptery- 
 goid process (r), above by the sphenoid united with the palate bone, and below by the 
 ualate bone. More externally is the pterygoid fossa (r), formed by the sphenoid, and a 
 small part of the palate bone. Still more externally, we find a deep fossa, or, rather, a 
 large space bounded internally by the external plate of the pterygoid process and th# tu- 
 berosity of the maxillary bone, and externally by the ramus of the inferior maxilla ; it is 
 known by the name of the zygomatic fossa. 
 
 The horizontal portion is the aixh of the palate {i x y, fig. 21). It is of a parabolic form, 
 extremely rough, and, in the fresh state, covered by the palatine mucous membrane. It 
 is constituted by the palatine processes of the maxillary bones (x), and by the horizontal 
 portions of the palate bones (y), and presents, in consequence, a crucial suture, at the cen- 
 tral point of which the vomer is attached : hence the piece of anatomical nicety which 
 consisted in Eisking at what part of the skeleton it is possible to touch five bones at once 
 with the point of a needle. The arch of the palate is pierced by several foramina ; we 
 find here the inferior opening of the anterior palatine canal (1), which is single below, but 
 double above, so as to open into each nostril separately ; the posterior palatine canals (2), 
 which open at the posterior and external part of the arch of the palate ; and a groove, 
 which runs along the external edge of the arch, and lodges the posterior palatine vessels 
 and ner\'es at their exit from their canals. 
 
 The third portion is also vertical : it presents, 1. In the median line, the suture of the 
 two superior maxillary bones, the interval between the middle incisor teeth of each jaw, 
 the symphysis menti, and the genial processes. 2. On each side, the posterior surface 
 of the alveolar border of the upper jaw, and the two rows of teeth which lie across each , 
 other like the blades of scissors in the middle, but meet posteriorly. 3. The posterior 
 surface of the inferior maxilla, the internal oblique line, the sub-lingual and sub-maxillary 
 fossae, and, lastly, the base of the inferior maxilla. 
 
 Zygomatic or Lateral Regions. 
 
 These regions are bounded above and on the outside by the zygomatic arch ; above 
 and on the inside by the transverse ridge which separates the temporal from the zygo- 
 matic fossa. They present first a plane surface, formed by the ramus of the inferior 
 maxilla ; when this part is removed, we observe the zygomatic fossa, the superior wall of 
 which is formed by the inferior surface of the great wing of the sphenoid, the anterior 
 by the maxillary tuberosity, the internal by the outer plate of the pterygoid process, and 
 the external by the ramus of the inferior maxilla. The posterior and inferior walls are 
 wanting. 
 
 At the bottom of this fossa, between the maxiUary bone and the anterior surface of 
 the pterygoid process, is a large vertical fissure, named by Bichat the pterygo-maxillary 
 fissure ; this opening leads into a sort of fossa, denominated by the older anatomists bot- 
 tom of the zygomatic fossa, and by Bichat spheno-maxillary fossa, which it is important to 
 study carefully, because five foramina or canals open into it, viz., three behind ; thefora' 
 men rotundum, the vidian or pterygoid, and the ptery go-palatine canals : a fourth on the in- 
 side, the spheno-palatine ; and a fifth below, the superior orifice o{the posterior palatine canal. 
 
 Lastly, the spheno-maxillary fossa presents, at the union of its superior with its ante- 
 rior wall, the spheno-maxillary fissure [fig. 21, before 3), which, on the one hand, makes 
 an acute angle with the sphenoidal fissure (or foramen lacerum orbitale), and, on the 
 other, a right angle with the pterygo-maxillary fissure. The spheno-maxillary fissure, 
 which is traversed solely by some nerves and vessels, is formed internally by the max- 
 illary and palate bones, externally by the sphenoid, and at its anterior extremity, which 
 is very broad, it is completed by the malar bone. 
 
62 OSTEOLOGY. 
 
 ■' Cavities of the Face. ---i. >*»..:•,. 
 
 TTie study of those bones which we have been engaged in examining has made us ac- 
 quainted with the existence of a great number of cavities, which considerably augment 
 the size of the face, and multiply its internal surfaces, without proportionally increasing 
 the weight. 
 
 All the cavities of the face may be reduced to three principal : viz., 1. The orbital cav- 
 ities ; 2. The nasal fossae, of which ail the sinuses are dependances ; and, 3. The buc- 
 cal cavitv, or mouth. 
 
 The Orbits. 
 
 These cavities, two in number, have the form of quadrangular pyramids, the axes of 
 which, prolonged backward, would intersect each other in the situation of the sella tur- 
 cica. It shoidd, at the same time, be remarked, that the internal wall of the orbit does 
 not participate in this obliquity, but is directed straight from before backward. We have 
 to consider in each orbit, a superior, an inferior, an external, and an internal wall ; four 
 angles which correspond to the intersection of these surfaces ; a base and an apex. 
 
 The superior wall, or roof of the orbit, formed by the frontal bone in front, and by the 
 orbital or lesser wing of the sphenoid behind, is concave, and presents from before back- 
 ward, 1 . Towards the outside, the lachrymal fossa. 2. On the inside, the slight depres- 
 sion in which the pulley for the superior oblique muscle is attached. 3. The suture be- 
 tween the lesser wing of the sphenoid and the orbital plate of the frontal.bone. 4. The 
 foramen opticum. 
 
 The inferior wall, or floor, forms a plane inclined outward and downward, and pre- 
 senll from before backward, 1. The infra-orbital canal. 2. A suture which marks the 
 union of the malar bone with the superior maxilla. 3. The orbital surface of the superior 
 maxilla. 4. A suture which marks the union of the superior maxilla with the palate bone. 
 5. The orbital facette of the palate bone. 
 
 The external wall, formed by the sphenoid and the malar bone, presents an almost ver- 
 tical suture, which indicates internally the spheno-jugal suture. 
 
 The internal wall, formed by the os unguis, the ethmoid, and the sphenoid, presents 
 two vertical sutures : in front, that which unites the os unguis to the ethmoid, and be- 
 hind, that which unites the ethmoid to the sphenoid. In front of these sutures is the 
 lachrymal groove, formed by the union of the os unguis and the ascending process of the 
 superior maxilla ; at the lower part of this groove we find the wide and very oblique ori- 
 fice of the nasal canal or duct, which opens into the middle meatus of the nose, and es- 
 tablishes a direct communication between the orbital and nasal cavities. 
 
 Of the four angles, two are superior and two infetior. Of the two superior, one is in- 
 ternal, the other external. The external superior angle presents the sphenoidal fissure 
 behind, and the inner aspect of the spheno-frontal and fronto-jugal sutures. 
 
 The internal superior angle presents the suture of union of the frontal bone with the 
 ethmoid behind, and with the os unguis in front. The orifices of the two internal orbital 
 foramina are seen in the situation of this suture. 
 
 Of the two inferior angles, the external presents the spheno-maxillary fissure, a portion 
 of the malar bone, and the opening of the jugal canal. The internul presents an uninter- 
 rupted horizontal suture, which unites in front the maxillary bone to the os unguis ; 
 more posteriorly, the maxillary bone, and then the palate bone, to the ethmoid. The 
 base of the orbit is cut obhquely from within outward, and from before backward ; its ver- 
 tical diameter is, for the most part, quite perpendicular to the horizon, but is sometimes 
 rendered slightly oblique by the projection of the frontal sinuses. At the apex of the or 
 bit is the union of the sphenoidal, the spheno-maxillary, and pterygo-maxillary fissures. 
 
 The Nasal Fossa. 
 
 These fossae are two in number, separated from each other by a vertical septum di- 
 rected from before backward ; they are situated in the middle of the face, and are pro- 
 longed into the interior of several of the bones of the face and cranium by means of the 
 cavities called sinuses. To describe their situation more exactly, we may say that they 
 are placed below the anterior and middle part of the base of the cranium, above the cav- 
 ity of the mouth, between the orbits, and the canine and zygomatic fossae of each side. 
 In order to have an exact idea, either of the dimensions or the shape of the nasal fossae, 
 it is necessary to have recourse to horizontal and vertical sections, of which the latter 
 should be made both from before backward and from side to side. 
 
 With regard to their dimensions, the nasal fossae (see figs. 22 and 37) present, 1. A 
 vertical diameter, larger in the middle than before or behind. 2. A transverse diameter 
 much shorter than the other two, and gradually contracted* from the lower to the upper 
 part, on account of the obliquity of the external wall. 3. An antero-posterior diameter, 
 which measures the whole of the interval between the anterior and posterior openings 
 of the nares. 
 
 * This pro^essivo contraction of the nasal fosss from below upward, and the obliquity of the externa! 
 wall, ought to be remembered during the introduction of instruments into the nose. 
 
THE FACE IN GENERAL. ^ 
 
 ■ The nasal fossae have a horizontal direction, but are nevertheless slightly inclined 
 backward and downward ; this is caused by the sloping of the inferior wall and the ob- 
 liquity of the body of the sphenoid, which fonns part of the superior wall. They are 
 irregular cavities, and have four walls ; a superior, an inferior, an internal, and an ex- 
 ternal ; and two orifices, an anterior and a posterior. 
 
 The superior wall or roof of the nasal fosses presents a concavity looking downward : it 
 o : :rraefl 1 In front by the proper bones of the nose, and in a small degree by the na- 
 sal spine of tne frontal bone. 2. In the middle, by the cribriform plate of the ethmoid. 
 3. Behind, by the body of the sphenoid. In this wall are two transverse sutures, name- 
 ly : before, the suture which indicates the union of the nasal and frontal bones, and be- 
 hind, that which marks the union of the ethmoid and sphenoid. At the back part of this 
 wall the opening of the sphenoidal sinus is seen. 
 
 The inferior wall or floor, much broader but shorter than the superior, presents a trans- 
 verse concavity ; it is directed from before backward, and slightly from above downward, 
 which arrangement concurs in determining the obliquity of the nasal fossae. It is form- 
 ed, in front by the superior maxilla ; behind, by the palate bone ; a transverse suture 
 marks the union of these bones. Near its anterior extremity, and at the side of the me- 
 dian line, the floor of the nasal fossa? shows the superior orifice of each branch of the an- 
 terior palatine canal {g, fig. 22, and o, fig. 37). 
 
 The internal wall (see fig. 22) formed by the septum is generally flat, but sometimes 
 concave or convex, according as it is bent to one or the other side.* 
 We find here the suture which indicates the union of the vomer with the perpendicu- 
 ' lar plate of the ethmoid (3 4, fig. 22) ; the septum in the skeleton is deeply notched in 
 front, and this notch (14 8), which is formed above by the perpendicular plate of the eth- 
 moid, and below by the vomer, is occupied in the fresh state by a cartilage, called the 
 cartilage of the septum. 
 
 The external wall {fig. 37), remarkable for its anfractuosities, is formed by the ethmoid 
 (,6 c), the OS unguis, the palate bone (m y), the superior maxillary p^ 37_ 
 
 (* ic o), and the inferior turbinated bone (d). It presents from 
 above downward, 1. The superior turbinated bone, superior concha, 
 or concha of Morgagni (i), in front of which is a rough square sur- 
 face. 2. The superior meatus (between b and c), at the back part 
 of which we find the spheno-palatine foramen (n), and the open- 
 ing of the posterior ethmoidal cells. 3. Below the superior mea- 
 tus, the middle turbinated bone, or middle concha (c). 4. Below, the 
 middle meatus (between c and d), at the back of which is the open- 
 ing of the maxillary sinus already described {s-ee maxillary bone, 
 Jig. 25) ; and in front, the infundibulum (s, fig. 37), which leads 
 into the anterior ethmoidal cells. 5. The inferior turbinated bone, 
 or inferior concha (d). 6. The inferior meatus (m o), in which we 
 find the inferior orifice of the nasal canal. 
 
 The anterior and posterior openings of the nasal fossae have been described with the 
 anterior and inferior regions of the face. 
 
 General DevelopTnent of the Face. 
 
 The development of the face is not effected solely by an equable increase of its dimen- 
 sions ; for certain regions are at one period of life predominant, at another period rela- 
 tively smaller, which circumstances give rise to very characteristic differences of form 
 at different ages. 
 
 State of the interior Region of the Face at different Periods of Life. 
 
 In the Foetus. — The upper part of the face shows a remarkable predominance, depend- 
 ant upon the early development of the frontal bone and the great capacity of the orbits. 
 
 The middle portion, or the superior maxilla, on the contrary, is very much contracted 
 by the absence of the maxillary sinus and canine fossa ; the vertical dimensions of the 
 superior maxilla and of the palate bone are so small, that the edge of the orbit and the 
 alveolar border are almost contiguous. We should mention here that the prominence 
 of the alveolar border, which still encloses all the germs of the teeth, is the principal 
 cause of the absence of the canine fossa. Lastly, the inferior maxilla is contracted in 
 its vertical diameter, like the superior, and, like it, presents a decided prominence in 
 front, by reason of its enclosing the germs of the teeth in the alveoli. The inclusion of 
 the dental germs also, by causing the alveolar border to project, produces a degree of 
 obliquity downward and backward of the symphysis ; to these causes of the small extent 
 of the vertical dimension of the face, we must add also the inconsiderable height of the 
 ethmoid at this period. 
 
 * Sometimes the deviation of the septum is so considerable that the internal touches the external wall, and, 
 consequently, there is great difficulty in th« passage of the air. This circumstance has given nse ir some 
 cases to a suspicion of the existence of polypus. 
 
 i 
 
64 OSTEOLOGV. 
 
 The transverse dimensions of the face are very considerable at the level of the orbits , 
 at the lower part of the face, on the contrary, they are proportionally much less than in 
 the adult. 
 
 The characteristics, then, of the face of the foetus are, 1. The smallness of its verti- 
 cal dimension. 2. The predominance in size of its upper over its lower part. 
 
 In the adult, the development of the maxillary sinus, the widening and vertical exten- 
 sion of the alveolar arches, give to the face the expression which characterizes it at that 
 period of life. 
 
 In the aged, the loss of the teeth, and the disappearance of the alveolar edge, partly 
 restore to the face the expression which it had in tlie foetus ; but the elongation and prom- 
 iuence of the chin, which, from the diminution of the vertical diameter, approaches the 
 nose, and the symphysis of which is now oblique from behind forward and downward, 
 impress upon it a peculiar character. The obliquity of the cliin, just mentioned, is pre- 
 cisely the reverse of that which exists in the foetus. 
 
 State of the Lateral Regions in different jjges. 
 These regions undergo the fewest changes of all ; for if, on the one hand, the devel- 
 opment of the maxillary sinus tends to increase the prominence of the maxillary tuber- 
 osity in the adult, on the other, the inclusion of the dental germs in the superior max- 
 illa, during foetal life, compensates for the want of the sinus. 
 
 State of the Posterior Region of the Face at different ^ges. 
 
 In the guttural portion, this region presents, in the foetus and the infant, the foUowmg 
 circumstances : the posterior borders of the rami of the jaw are very oblique, instead oi 
 being almost vertical, as in the adult ; the pterygoid processes, and the posterior nasal 
 openings, are also directed very obliquely downward and forward, instead of vertically, 
 on account of the absence as yet of the maxillary sinus, which, during its development, 
 carries them backward. From the obliquity of the posterior border of the ramus of the 
 jaw, it follows that the articular surface of the condyle which surmounts it looks back 
 ward instead of upward. 
 
 In the horizontal or palatine portion, the inferior region of the face has proportionally 
 less extent from before backward than in the adult, on account of the obliquity of the 
 pterygoid process, and the slight development of the maxillary sinus. We perceive, 
 then, how great an influence the varying conditions of these sinuses exercise over the 
 whole configuration of the face, at the different periods of life. 
 
 It may be easily conceived that the cavities of the face must undergo important chan 
 ges during these alterations in the shape of the face which we have been describing. 
 The most remarkable is the tardy development of the nasal fossae compared with that 
 of the orbits. It may even be said that they proceed in an inverse ratio. The orbital 
 cavity, intended to receive the globe of the eye, which is already highly developed at the 
 time of birth, is of great capacity. This magnitude it owes entirely to the rapid growth 
 of the frontal and sphenoid bones ; because the malar bone and the superior maxilla con- 
 tribute but little towards it, and the height of the ethmoid is so small, that the vertical 
 diameter of the orbit, which depends upon that of the ethmoid, is less considerable than 
 its transverse diameter. The nasal fossas, which are very small in the foetus, gradually 
 acquire an increased extent of surface, by the growth in height of the ethmoid, the pal- 
 ate bone, the superior maxillary, and the vomer, and by the augmented size of the turbi- 
 nated bones ; and their surface is still farther extended by the enlargement of the max- 
 illary, sphenoidal, and frontal sinuses, and the ethmoidal cells. The development of 
 the frontal sinus, it may be observed, is owing chiefly to the separation of the two tables 
 of the bone, the anterior of which is almost always thrown forward, the posterior remain- 
 ing stationary. There are, however, some examples on record, in which it was evident 
 that the sinus was formed almost exclusively by the retrocession of the posterior table. 
 
 THE THORAX, OR CHEST. 
 
 The Sternum. — Ribs. — Costal Cartilages. — The Thorax in general. — Development. 
 
 The thorax {■&upa^, the chest) is a sort of bony cage intended to contain and protect 
 the principal organs of respiration and circulation. The parts which enter into its com- 
 position are twelve dorsal vertebrae behind, the sternum in front, and twelve flexible 
 bones named ribs, on each side. We have already described the dorsal vertebrae, and 
 have now, therefore, only to notice the sternum and the ribs. 
 
 The Sternum (a b c,fig. 38). 
 The sternmn, so named from the Greek word arepvov, the breast, is a kind of flat- 
 tened, symmetrical, bony column, which occupies the anterior and middle part of the 
 thorax. It is situated between the ribs, which support it like props. The clavicles, 
 
6S 
 
 and through them the upper extremities, rest upon its upper part as a basis, during their 
 movements. The sternum is not immovably fixed in its place; it is raised and de- 
 pressed, as we shall point out in describing the mechanism of the thorax. 
 
 The length of the sternum, which is proportionally smaller in the female than in the 
 male, varies from 5^ to 7i inches. At its upper part its breadth is from IHo 2 inches ; 
 it then becomes contracted, then again expands, and terminates below in a very nar- 
 row extremity. Its thickness above is about 6 lines ; at its lower part it is much thin- 
 ner, never exceeding 3 hues. 
 
 With regard to figure, the sternum was compared by the ancients to the sword of a 
 gladiator, and from this have arisen the denominations given to its various parts. The 
 upper part {a), which is broadest, has been called the handle (manubrium) ; the middle 
 part (J), the body {mucro) ; and the lower extremity (c), the poini ; xipJioid appendix {pro- 
 cessus cnsiformis). This division of the bone into three parts has been retained by some 
 modern anatomists, who describe the three pieces of the sternum separately as so many 
 distinct bones. We shall adhere to it only, however, in speaking of the development of 
 the bone. 
 
 The sternum presents two surfaces, two borders, and two extremities. 
 
 1. The anterior or cutaneous surface is shghly convex, and forms an oblique plane down- 
 ward and forward ; it presents three or four projecting transverse lines, which are tra- 
 ces of the union of the original pieces of the bone, and divide it into surfaces of unequal 
 size. The line which marks the union of the first two pieces of the bone is the most 
 remarkable ; it causes a projection of variable size in different individuals, which has 
 been sometimes mistaken for a fracture or exostosis. At the lower part of this surface, 
 we find in some subjects a foramen which perforates the bone : sometimes, in place ot 
 this foramen, there is a considerable aperture, to which much importance has been 
 attached, as affording a proof of the primitive separation of the bone in the median hne. 
 The existence of this opening explains how purulent matter, deposited behind the ster- 
 num, may in certain cases make its way outward without any absorption of the bone. 
 The anterior surface of the sternum is covered by the skin, and an interlacement of 
 very numerous aponeurotic fibres. 
 
 2. The posterior, mediastinal, or cardiac surface (a b c), is slightly concave from above 
 downward, and presents, in young subjects, lines (e e) corresponding to those which 
 occupy the anterior ; but all which, excepting the one between the first and second pieces 
 of the bone, are effaced at a more advanced age. This surface is in relation with many 
 organs contained in the chest, and especially the heart, in front of which the sternum 
 forms a kind of shield.* At the lower part of this surface are several nutritious foramina. 
 
 3. The borders, very thick and sinuous, present seven articular cavities {d d, &c.), sep- 
 arated from each other by semilunar notclies, which are longer above than below, where 
 the facettes closely approach one another. The uppermost of these seven cavities is 
 shallow, triangular, and at an early age becomes ingrained with the cartilage of the first 
 rib ; those which follow are d^Sfttu angular, and situated at the extremities of each of 
 the lines (e e) above mentionfd:^J^ey are all intended to articulate with the cartilages 
 of the first seven ribs. WhenjgiSmined in a dried specimen, they appear more angiSar 
 and deeper in proportion to the^buth of the subject. 
 
 4. The superior or clavicular extremity is the broadest and thickest part of the whole 
 bone, presenting a notch, transversely concave, which bears the name of fourchette (/) 
 of the sternum (or semilunar notch) ; on each side {g g) is an oblong articular surface, 
 concave from without inward, convex from before backward, articulated with the clav- 
 icle, and surrounded with inequalities for the insertion of muscles and ligaments. It 
 frequently happens that the two clavicular facettes are not at the same height ; a fact 
 which was noticed by Morgagni, and which I have attributed to the unequal wearing of 
 the two articular surfaces. 
 
 5. The inferior or abdomj^nal extremity is formed by the xiphoid appendix (c) {^i^o^, a 
 sword), called also xiphoid'^ ensiform cartilage, because it often remains cartilaginous to 
 Hdult age. In length, shape, and direction, it presents numerous varieties ; it is fre- 
 quently bifid, sometimes pierced by a foramen, and is accasionally bent forward, or to 
 one side, and, in certain cases, much depressed : its summit gives attachment to an ap- 
 oneurotic structure, called the linea alba ; behind, it indirectly corresponds with the 
 stomach, which rests upon it when the body is placed in a prone position.! 
 
 * This use of the bone is eiemplified in many animals which are provided with a sternum, though they 
 hav« no ribs ; for example, the frog. 
 
 This bone has attracted much of the attention of the modem transcendentalists. By them it is regarded as 
 a vertebral column anterior to the intestinal canal in man, and inferior to it in the lower animals. Many of 
 them have conceived that they have found in it a cervical, a dorsal, and a lumbar regfion, &c., &c. 
 
 M. Cruveilhier, in the opinion of the editor, with much propriety, in the first edition of his work, took no 
 notice of the idle and fanciful speculations of the transcendentalists, either in reference to the sternum, or to 
 the analogy which exists between the bones of the cranium and the vertebrae. Although he lias, in the sec- 
 ond edition, introduced some notices in reference to the analogy which these gentlemen have attempted to 
 establish between the cranium and the vertebral column, believing that they only increase the size of the 
 book without adding to its value, we have excluded them. — Ed. 
 
 t In front this appendix is sub-cutaneous, and the skin which covers it is so sensible that the slightest con- 
 
 I 
 
66 OSTEOLOGY. 
 
 Connexions. — The sternum articulates with sixteen bones, viz., fourteen ribs through 
 the medium of their cartilages, and the two clavicles. 
 
 Structure. — It consists of two very thin compact laminae, with an intervening spongy 
 substance, the cells of which are very large, and have very delicate parietes ; it is one 
 of the most spongy bones of the body, and to this circumstance the frequency of its dis- 
 eases is doubtless attributable. 
 
 Development. — The sternum is one of the slowest bones in its ossification ; up tc the 
 sixth month of fcEtal life, the broad cartilage of which it is composed exhibits no bony 
 points. It is also, of aU the bones, the one in which the phenomena of ossification pro- 
 ceed with least regularity. For the sake of simplicity, we shall study in succession the 
 development of the three parts which we have indicated, under the names of manubrium, 
 body, and xiphoid appendix. 
 
 1. Ossification of the Manubrium. — This part of the bone sometimes presents a single 
 nucleus, rounded, and transversely oblong ; sometimes it presents two nuclei, and, in this 
 case, they may be either placed one above the other, or side by side. In the former 
 case, the uppermost nucleus is the larger ; in the latter, both may be symmetrical and 
 of equal size, or, what is far more common, they may be of unequal magnitude. Lastly, 
 the manubrium occasionally presents more than two osseous points. Albinus found three 
 in one subject and four in another. 
 
 It should be remarked, that in the case of plurality of osseous points, the largest are 
 generally situated above : the exceptions to this rule are very rare. The osseous points 
 make their appearance from the fifth to the sixth month of foetal life. 
 
 2. Of the Body. — The osseous nuclei which enter into the composition of the body of 
 the sternum have generally a rounded form when they are single, and are situated in the 
 median line ; when they exist in pairs, or are placed laterally, they are more elongated, 
 but smaller, and appear to represent only the half of one of the single nodules. These 
 different osseous points are always so arranged as to be situated between two costo- 
 sternal articulations, so that a portion of the sternum is developed in each of the inter- 
 vals comprised between two ribs. The last piece is the only exception, being common 
 to the articulation of the sixth and seventh ribs. 
 
 If there be more osseous points than one in an intercostal space, these, as Albinus has 
 remarked, are invariably placed laterally, not one above the other. 
 
 There are, therefore, four primitive pieces in the body of the sternum, and each of 
 these is sometimes formed by one point of ossification ; at other times, by two lateral 
 points. 
 
 The following is the order in which the ossification of the body of the sternum pro- 
 ceeds : the two upper pieces first appear from the fifth to the sixth month of foetal life ; 
 the third is visible at the sixth month ; the fourth most conunonly makes its appearance 
 after birth, but sometimes towards the end of gestation. 
 
 In the ossification of the body of the sternum, we more frequently find examples of 
 two symmetrical nodules placed on opposite sides of the median line, than in the develop- 
 ment of the manubrium, f^*^ 
 
 Union of the Points of Ossification of the Body. — In cqjteidering the union of the differ- 
 ent parts which compose the body of the sternum, it i?|i|Mpssary to make a distinction 
 between the lateral conjunction, that is, the union of the osseous points which are situated 
 on each side of the median line, and the vertical conjunction, or the union of the pieces of 
 the sternum properly so called. The lateral conjunction, or the union of those osseous 
 germs which form a pair in the same interval, always precedes the vertical conjunction. 
 The vertical conjunction, oj the union of the pieces of the body of the sternum together, 
 commences with the two inferior portions. After this union, the body of the bone con- 
 sists only of three parts. The second piece then unites with the lower ; the sternal 
 foramen is found sometimes at the junction of these last-mentioned parts, sometimes at 
 the place where the two lateral points of the fourth and of the third portion of the body 
 are united. The first piece of the body is not united to the two others until from the 
 twentieth to the twenty-fifth year. 
 
 It should be observed, that the union of the divisions of the body of the sternum takes 
 place precisely in the inverse order of their appearance. In fact, the appearance of the 
 osseous points proceeds from above downward, their union from below upward ; a fact 
 which verifies an assertion formerly made, viz., that the order of development of osseous 
 points is not always correlative to the order of conjunction. 
 
 3. Ossification of the Appendix. — This is generally accomplished by one nodule : some- 
 
 tusion produces, even in the most powerful men, syncope.* This fact may explain the importance which has 
 been«ttached to the configuration of this process, and to the names "pit of the stomach," " scrobiculus cordis," 
 " pracordittm," which have been given to the region which corresponds to it. Much has been said of the dis- 
 placement of the Kiphoid appendix, and of the accidents to which this has given place ; but, in reality, these 
 displacements hare never been observed, and the accidents which have been attributed to them have most cer- 
 tainly depended on&n injury inflicted on the parts situated behind it. 
 
 * We do not believe that the skin situated over this appendix is more sensible than the skin elsewhere. 
 The syncope which follows a blow here is, in our opinion, produced by the impression it produces on the in» 
 temal organs. — Ed. 
 
THE RIBS. 
 
 6¥' 
 
 tunes there are two, and then they are rarely symmetrical. The process commences in 
 the upper part of the cartilage, and very rarely extends through the whole. The time 
 of appearance of the osseous point is extremely variable ; sometimes it is visible to- 
 wards the third or fourth year ; sometimes not until the twelfth, or even the eigh- 
 teenth year. 
 
 In adult age, the sternum is composed of the three parts the development of which I 
 have just noticed, and which the ancients considered and described as distinct bones. 
 From the fortieth to the fiftieth year, and sometimes later, the appendix becomes united 
 to the body, which very rarely joins the manubrium ; when such is the case, the union 
 is more apparent than real ; for if the bone be cut verticdly, the articulation is apparent, 
 under a very thin layer of osseous matter. 
 
 From what has been said of the numerous varieties of ossification, it will be evident 
 that it is impossible to assign to this bone a limited number of osseous points. To those 
 which have been noticed I would add two others, described by Beclard under the name 
 of supra-sternal points, which I have seen once only in the sternum of an adult, in the 
 form of pisiform nodules, placed on each side of the semilunar notch of the stemiun. 
 
 The Ribs (1 to 12, Jig. 38). 
 
 The ribs (^costce, from custodes, as if, according to the explanation of Monro, they were 
 the guardians of the organs of the chest) ^^^^ 3g 
 
 are osseous arches stretched from the ver- 
 tebral column to the sternum. Their pos- 
 terior four fifths consist of bone ; the ante- 
 rior fifth is cartilaginous. The osseous 
 portion is the rib, properly so called ; the 
 cartilaginous portion is named the costal 
 cartilage. 
 
 The ribs are 24 in number, 12 (1 to 12) 
 on each side. Sometimes there are 26, 
 thirteen being on each side, and then these 
 supernumerary ribs are formed either from 
 a part of the transverse process of the sev- 
 enth cervical vertebra, or of the transverse 
 process of the first lumbar, which affords an 
 evident proof of the analogy existing be- 
 tween these parts. Sometimes, but more 
 rarely, there are only 22 ribs, an anomaly 
 pointed out by Galen. In this case, we 
 sometimes find two adjacent ribs united 
 throughout their entire length, sometimes 
 the first rib in a rudimentary state, being 
 properly formed posteriorly, but having its 
 anterior extremity lost in the>substance of 
 the scaleni muscles, or united to the second 
 rib, and through it joined to the sternum.* 
 
 The ribs are divided into two classes : 
 1. Those which extend from the vertebrae 
 to the sternum, the true ribs, sternal or ver- 
 tebrosternal ribs (1 to 7). 2. Those which 
 do not reach the sternum, the false, aster- 
 nal, or vertebral ribs (8 to 12). The last two 
 false ribs (11 12) are called floating, because their anterior extremity is movable in the 
 fleshy parietes of the abdomen. The ribs are designated numerically ;5rs^, second, &c., 
 counting from above downward. It should, however, be observed, that in many surgi- 
 cal works, the ribs are counted from below upward, which is the easiest method on the 
 living subject. 
 
 The ribs have certain general characters which distinguish them from all other bones 
 and certain proper characters, by which one is known from another. 
 
 General Characters of the Ribs. 
 The ribs resemble flattened bony arches of about six lines in breadth, and one in thick- 
 ness, and of lengths varying according to their situation. The first rib is almost hori- 
 lontal, and the others in succession slope gradually more obliquely from behind forward, 
 and from above downward, their anterior extremities being on a much lower plane than 
 the posterior. Considered with regard to their axes, i. e., their absolute direction, the 
 ribs represent portions of a circle which successively increase to the eighth, and dimin- 
 
 * la a subject prepared for my lectures, the transverse processes of the second, third, and fourth lumbar 
 vertebrae were elongated, so as to form supernumerary ribs, while the transverse process of the first was un- 
 changed. 
 
09}, OSTEOLOGY. 
 
 ish again to the twelfth ; their curvature is not regular, the posterior part representing 
 the segment of a much smaller circle than the anterior. They are generally tvnsted upon 
 themselves, so that their two extremities cannot rest at once upon the same horizontal 
 plane. The point where this torsion exists is marked on the convex surface by an ob- 
 lique projecting line, called the angle (Ji) of the rib ; but it is not correct to consider the 
 angle of the rib as resulting from this torsion ; it appears to me simply intended for mus- 
 cular insertions. 
 The ribs have a body and two extremities. The posterior or vertebral extremity is 
 Fig. 39. thicker than the rest of the bone, whence it has received 
 
 the name of head (i) {capitulum casta), and presents two half 
 surfaces (c c, fig. 39), of which the upper is smaller than the 
 lower, separated by a horizontal ridge. These two facettes 
 articulate with corresponding surfaces on the bodies of the 
 dorsal vertebrae {d rf, fig. 39). The head is supported by a 
 constricted portion, the neck (k, fig. 38), which is flattened 
 from before backward, and is the weakest part of the bone. 
 It presents behind some inequalities which correspond to the 
 _ transverse process of the dorsal- vertebra below. Externally 
 
 to the neck is an eminence known as the tubercle \l I) of the rib ; it is divided into two 
 parts, which are united at an angle, viz., an internal and inferior portion {I), smooth and 
 convex, which articulates with the transverse process of the vertebra below the particu- 
 lar rib examined ; and an external rough portion (Z), which gives attachment to liga- 
 ments. The tubercle is in general most prominent in the upper ribs. 
 
 That part of the rib which is included between the head and the tubercle {neck, cervix) 
 is directed from within outward, and slightly from above downward, so as to reach the 
 summit of the transverse process of the vertebra below. Beyond the tubercle, the rib 
 still follows the same direction for not more than fifteen lines ; it is then bent decidedly 
 forward. The situation of this curve, which corresponds with the torsion of the edges 
 above mentioned, is at the angle of the rib. The interval which separates the tuberosity 
 from the angle is the thickest and strongest part of the rib. 
 
 The rest of the rib which is before the angle becomes broader and thinner, and is di- 
 rected forward, so that, as Haller expresses it, the line which it describes represents in 
 some measure the tangent of the posterior curve. The anterior extremity (m) has a 
 hollowed oval facette for receiving the cartilage. Besides the objects we have already 
 described, we observe, near the anterior extremity of the rib, an oblique line, analogous 
 to that which forms the angle, but much less marked. This line may be considered as 
 forming the anterior angle of the ribs, and, like the posterior, it is intended for muscular 
 insertions. 
 
 From what has been said, we perceive that the ribs present, 1. A posterior extremity 
 or head, supported by a neck ; S. An anterior extremity united to the costal cartilage ; 3. A 
 body, having an external, or cutaneous surface, which is convex ; and an internal, or pul- 
 monary surface, which is smooth and concave ; a superior edge, which is curved, thick, 
 and rounded ; and an inferior edge, which has a greater dujprature than the superior, is 
 thin and sharp, and marked by a groove or furrow on the inner surface, called the groove 
 of the ribs {e, fig. 39), which receives and protects the intercostal vessels and nerves. 
 Lastly, the ribs have a double curvature, one of the surfaces, another of the edges ; this 
 last is the curvature of torsion. 
 
 Connexions. — The ribs are articulated, behind, with the dorsal vertebrae ; in front, with 
 the costal cartilages. 
 
 Structure. — The external aspect of a rib resembles a long bone ; but the internal con- 
 formation is analogous to that of flat bones. The compact and spongy substances are 
 so distributed that these bones enjoy a certain degree of flexibility, with great power of 
 resistance. In young subjects, the compact substance is in excess ; in the aged, and in 
 certain diseases, the opposite is the case ; hence the extreme fragility of these bones, 
 which are then broken by the least effort. 
 
 Development of the Ribs. — The ribs are among the earliest developed of the bones, the 
 'ossification of their bodies commencing from the fortieth to the fiftieth day after concep- 
 tion. They are developed by three osseous points : one primitive, and two epiphysary. 
 The primitive point by itself forms the body of the bone. Of the two epiphysary points, 
 one is intended to form the hccid of the rib, the other the tubercle. They appear from 
 the sixteenth to the twentieth year, and they unite with the rest of the bone about the 
 twenty-fifth year. These epiphysary points do not exist in the two lower ribs, which, 
 consequently, have only one point of ossification. 
 
 Special Characters of different Ribs. 
 The differential characters of the ribs have reference, first, to the length, which increas- 
 es gradually from the first to the seventh, and diminishes again to the twelfth ; secondly, 
 to the curvature, the four upper ribs being parts of much smaller circles than the rest, 
 and thus forming the summit of the cone of the chest, while the lower ribs constitute its 
 
COST'XL CAST ILAGES. 18^ 
 
 ISase ; and, lastly, to certain peculiarities of conformation in the first, second, third, elev 
 enth, and twelfth ribs, which require special description. 
 
 The first rib {\,fig. 38, and^. 40) is the shortest, and proportionally the broadest of 
 all the ribs, thus forming an imperfect hd to the bony case which p- ^q 
 
 constitutes the thorax. Its edges are curved, but its surfaces 
 are flat. The curve which it describes forms part of the circum- 
 ference of a much smaller circle than any of the other ribs. The 
 
 posterior extremity has a small head with a single convex facette r^M ^^^k 
 
 (a, fig. 40), supported by a long, thin, and cylindrical neck (b). 
 The tubercle (c) is very prominent ; it occupies the external bor- 
 der, and gives an angular appearance to this rib. The anterior 
 extremity {d) is broader than that of any other rib. Of the two surfaces, one is directed 
 upward and slightly outward, the other downward and a little inward. The superioi 
 surface {fi^. 40) has two depressions separated by a tuberosity (e). The anterior corre- 
 sponds to the subclavian vein ; the posterior to the artery of the same name. The tu- 
 berosity which separates them gives attachment to the anterior scalenus muscle. The 
 internal edge (a e d) is concave ; the external (a c d) is convex, and has no groove. The 
 first rib has neither a curvature of torsion, nor an angle ; so that the whole of it can rest 
 upon the same horizontal plane. The superior surface presents, also, near its anterior 
 -extremity, a depression, which appears to result from pressure by the clavicle, which I 
 have seen, in some cases, immediately articulated with this bone. 
 
 The second rib (2, fig- 38) preser\'es many of the characters of the preceding, but dif- 
 fers essentially in its length, which is at least double ; it belongs to a much larger circle : 
 it has no curvature of torsion, and can rest upon the same plane with its two ends ; the 
 angle is scarcely visible. The external surface is directed upward ; it presents in the 
 middle a very rough eminence for the attachment of the serratus magnus muscle. The 
 internal surface looks obliquely downward ; near the tubercle it has a very smtill groove. 
 
 The third rib (3, fig. 38) differs from the second by its great length, by the presence 
 of the angle, and by a curvature of torsion sufficient to prevent the two ends from rest- 
 ing at once upon the same horizontal plane. 
 
 The eleventh and twelfth ribs (11 l^,fig- 38) differ from all the others by the following 
 characters: 1. They form segments of much larger circles than any of the others; 2. 
 Their heads have only one articular facette, and this is flattened ; 3. They have no 
 neck, properly so called ; 4. They have no tubercle : 5. They have no groove ; 6. They 
 have a very thin and pointed anterior extremity. These two ribs differ from each other 
 only in length, the twelfth being the shorter. 
 
 The Costal Cartilages (T to \1\jig. 38). 
 The flexibility and elasticity of the ribs is partly owing to their structure, but more 
 ' especially to the costal cartilages which prolong them in front. There are twelve cos- 
 tal cartilages, distinguished niunerically as first, second, third, &c. ; they are separated 
 from each other by intervals, which are very considerable at the upper part of the tho- 
 rax, but gradually diminish as we proceed downward : it is not very uncommon to meet 
 with thirteen cartilages on one side ; at other times there are only eleven. We some- 
 times find two cartilages which are joined together, and articulated with the sides of 
 the sternum ; when there are thirteen cartilages, the supernumerary one generally exists 
 between the third and fourth ribs ; it is thin, and, as it were, rudimentary ; it does not 
 form the continuation of any rib, and terminates insensibly in the muscles. The first 
 seven cartilages (1 to 7) articulate immediately with the sternum ; and hence the name 
 of sternal given to the ribs with which they are connected. Of the other five cartilages, 
 the last two (11 12) have no connexion with those that precede them; and, from this 
 circumstance, the navae floating has been given to the last two ribs. 
 
 General Characters of the Costal Cartilages. 
 All the costal cartilages are flattened like the ribs, and precisely resemble, in breadth 
 and thickness, the bones to which they are attached. The external end is received into 
 a cavity hollowed out in the anterior extremity of the rib : their internal or sternal ex- 
 tremity, which is much narrower than the external, is angular, and articulates with the 
 corresponding angular facettes of the sternum. Their anterior or cutaneous surfaces 
 are slightly convex, and covered by the muscles of the anterior region of the trunk, to 
 many of which they give attachment. Their posterior or mediastinal surfaces are 
 slightly concave. Their superior and inferior edges bound the intercostal spaces, and 
 give attachment to the muscles of the same name. They are altogether distinct from 
 articular cartilages, and have a peculiar tendency to ossify, this process taking place 
 partly on the surface, and partly from within outward. 
 
 Differential Characters of the Costal Cartilages. 
 The costal cartilages increase in length from the first to the seventh, and sometimes 
 to the eighth, which in this case articulates with the sternum ; they diminish in length 
 
70 OSTEOLOGY. 
 
 from the seventh to the twelfth. This difference depends on the circumstance that the 
 osseous parts of the upper ribs terminate anteriorly in a line directed obhquely from 
 above downward, and from within outward, and that the sternum is only about half the 
 length of the lateral wall of the thorax, so that only the first four or five cartilages could 
 join this bone, did not the others bend upward, so as to reach its sides or join the lower 
 edge of the cartilage above ; the first three cartilages alone, therefore, follow the same 
 direction as the bony rib. The first cartilage differs from all the others by its shortness, 
 its thickness and breadth, and its tendency to ossify ; it is ahnost always bony in the 
 ■ adult ; it is often continuous with the sternum, but is sometimes only contiguous, in 
 which case its articulation to this bone presents a great difference as respects motion. 
 The second and third costal cartilages cannot be distinguished from each other, but they 
 differ from the rest in being joined at right angles with the sternum, in not being bent, 
 and in being as broad at their sternal as at their costal extremities. The fourth carti- 
 lage becomes bent upward, after having followed the direction of the rib for a little way. 
 The length and curvature of the cartilages of the fifth, sixth, and seventh ribs progres- 
 sively increase : the seventh is at least three inches long, whUe the fifth is not more 
 than thirteen or fourteen hues ; their inner ends become successively narrowed, so as 
 to correspond with the diminishing cavities on the edges of the sternum ; the borders 
 of the fifth, sixth, seventh, and eighth costal cartilages articulate together, and present, 
 for this purpose, articular facettes, supported by eminences. The cartilages of the 
 eighth, ninth, and tenth ribs gradually diminish in length ; externally they have the same 
 breadth as the rib, and decrease as they pass inward, so as to terminate by a pointed 
 extremity, which is applied to the lower edge of the rib above. The cartilages of the 
 eleventh and twelfth ribs are extremely short, especiaUy that of the twelfth, which is 
 only a few lines in length ; their internal free extremity loses itself, so to speak, in the 
 substance of the abdominal parietes, so that they are altogether unconnected with the 
 other cartilages. 
 
 The Thorax in genekal. 
 
 The sternum, the ribs, and the whole dorsal region of the vertebral column, form the 
 framework of a large visceral cavity, the thorax, intended to contain and protect the 
 chief organs of respiration and circulation. It occupies the upper part of the trunk, be- 
 tween the thoracic extremities ; its boundaries are very well defined above, but below 
 there is not any line of demarcation in the skeleton between the cavities of the thorax 
 and abdomen ; or, rather, the bony thorax is common to the thoracic and abdominal vis- 
 cera. We shall see afterward, that these two cavities are separated from each other 
 by a movable and muscular septum called the diaphragm. 
 
 With regard to capacity, the thorax holds a middle place between the cavity of the 
 cranium and that of the abdomen. In each individual, the capacity of the thor2ix is ex- 
 actly proportional to the volume of the lungs ; and as, in general, voluminous lungs co- 
 exist with a highly-developed muscular apparatus, it follows that the size of the thorax 
 is no equivocal sign of a vigorous constitution. The thorax differs much from the ab- 
 dominal cavity in regard to its extensibility, being only capable of very Umited alternate 
 movements of dilatation and contraction. In the structure of the thorax, we find the 
 twofold condition of solidity and mobility in so perfect a degree,, that the framework of 
 which it is composed is equally fitted to serve as a protecting structure and a respira- 
 tory apparatus. This limited dilatabihty contrasts, on the one hand, with the almost in- 
 definite extensibility of the abdominal cavity, and, on the other, with the absolute want 
 of extensibility in the cranium. 
 
 We should form a very incorrect idea of the dimensions and shape of the thorax, if 
 we were to judge of them by its external aspect while still covered by the soft parts, 
 and surrounded by that species of girdle which is formed by the shoulder round its upper 
 part ; for we should then conclude it to be a truncated cone, with the base above. On 
 the contrary, when the surrounding parts are removed, the thorax represents a cone, 
 the base of which is in precisely the opposite direction, that is, below. The height of 
 Ihe thorax cannot be measured with exactness, because it varies according to the de- 
 pression or elevation of the muscular septum, which intervenes between the thoracic 
 and the abdominal cavities. We can only say, that the bony framework should be di- 
 vided into two parts, a superior or supra-diaphragmatic, which belongs to the chest, prop- 
 erly so called, and contains the lungs and heart ; and an inferior, which forms part of 
 the cavity of the abdomen, and contains the liver, the spleen, the kidneys, the stomach, 
 the duodenum, and part of the colon. It should be also remarked, that the supra and 
 sub-diaphragmatic portions of the thorax constantly vary in their respective proportions ; 
 and that these variations of height principally take place at the sides, the middle remain- 
 ing always nearly the same. The transverse diameters increase rapidly from the upper 
 to the lower part of the thorax. The same is true of the antero-posterior diameters, and 
 these also sensibly increase opposite the concavity of the dorsal region of the spine. 
 The antero-posterior diameters are much greater laterally than in the median line, 
 where they are diminished by the considerable projection of the bodies of the dorsal ver- 
 
THE THORAX IN GENERAL. 71 
 
 tebrae. This shortness of the antero-posterior diameters between the sternum and the 
 vertebral column is in proportion to the small size of the heart, which is situated in 
 this region, as compared with that of the lungs, which occupy the sides. 
 
 Antero-posterior Flattening. — The cone represented by the thorax is flattened from be- 
 fore backward. This flattening appears to be connected with the existence of the clav- 
 icle, for we meet with it in all animals provided with this bone, while in those in which 
 it does not exist the flattening is lateral, i. e., from one side to the other. 
 
 The shape of the thorax is subject to many varieties, as respects different individuals, 
 age, sex, &c. Of the individual varieties, some are compatible with health, others are 
 pathological, and constitute malformations, the history of which belongs to the subject 
 of diseases of the chest. Sometimes they are congenital ; at other times they are the 
 result of accidental circumstances which have modified the primitive conformation. 
 
 In some subjects the lateral exceeds the antero-posterior flattening, and the sternum 
 is prominent, as we habitually see it in the thorax of phthisical patients. 
 
 Many individual varieties of conformation of the thorax are the effect of frequently 
 repeated, or permanent compressions exercised on the bony cavity. I have seen infants 
 in whom the thorax was perfectly well formed at birth, but had been deformed and flat- 
 tened on the sides by pressure from the hands of the nurse. If there be, in fact, a time 
 when the slightest external pressure may be productive of permanent deformity, it is 
 during the first years of life. The effects of a strong and permanent constriction are 
 also manifest in a very evident manner, in the alterations of the form of the thorax con- 
 sequent upon the use of stays. This species of constriction affects principally the lower 
 part of the chest ; so that the fifth, sixth, seventh, eighth, ninth, and tenth ribs are press- 
 ed forward and inward, because the length and flexibility of their cartilages allow them 
 to yield readily ; and all the viscera which correspond to this species of girdle undergo 
 very marked alterations in their direction, and even in their figure and position. Thus 
 the liver, the spleen, and the stomach are forced upward and compress the lungs, which, 
 in their turn, are pushed to the upper part of the chest, and have a tendency to pass con- 
 siderably beyond the level of the first rib ; 2. The stomach becomes more oblique ; 3. 
 The transverse arch of the colon is often forced downward ; the pregnant uterus acquires 
 an oblique direction. In an old female, whose thorax was so contracted below as to 
 present the appearance of a barrel, and bore witness to the use of a very tight corset, 
 the cartilage of the seventh rib, on the right side, was in contact with that of the oppo- 
 site rib ; the xiphoid appendix was strongly depressed, and pushed behind the cartilages 
 of the seventh and eighth ribs, which touched each otlier. Some varieties of conforma- 
 tion depend upon deviations of the vertebral column ; they evidently belong to patholo- 
 gic2il anatomy, and need not occupy our attention. In the female, the chest resembles 
 a cone, with a larger base, but of less height than in the male. 
 
 There are certain varieties at different ages, which will be noticed in the history of 
 the general development of the thorax. 
 
 As the thorax does not form a regular cone, when we speak of its axis being directed 
 obhquely from above downward, and from behind forward, we only refer to its anterior 
 wall, the posterior and latereil being altogether devoid of this obliquity. 
 
 We shall now consider in detail the external and the internal surface of the thorax ; 
 the inferior circumference or base, and the superior circumference or summit, resulting 
 from its conical form. 
 
 External Surface of the Thorax. 
 
 On this surface we find an anterior, a posterior, and two lateral regions. 
 
 The anterior or sternal region, much wider below than above, forms a plane inclined 
 from above downward, and from behind forward, and more or less projecting according 
 to the general conformation of the thorax. It presents, 1. In the middle, the cutaneous 
 surface of the sternum; 2. On the sides, the series of articulations of the cartilages of 
 the ribs with the sternum ; 3. The costal cartilages, those being the longest which ap- 
 pertain to the lower ribs ; 4. Between the cartilages, certain intervals named intercostal 
 spaces ; 5. Externally to the cartilages, an oblique line running from above downward, 
 and from within outward, and marking the series of articulations of the costal cartilages 
 with the ribs ; 6. Still more externally, another oblique line, wliich has not been pointed 
 out, and which is formed by the anterior angles of the ribs ; it corresponds in obhquity 
 with the chondro-stemal Hne, and forms the boundary of the anterior region. 
 
 The posterior or vertebral region presents, in the median line, the series of dorsal spi- 
 nous processes ; on the sides, 1. The vertebral grooves ; 2. The series of dorsal trans- 
 verse processes ; 3. Their articulation with the tubercles of the ribs ; 4. A series of 
 surfaces, of which the lower are the largest, and which are comprised between the angle 
 and the tubercle of each rib ; 5. Lastly, an oblique line, running from above downward, 
 and from within outward, formed by the posterior angles of the ribs. 
 
 The lateral or costal regions resemble a sort of curved grate, more convex behind than 
 in front, and showing the series of ribs and intercostal spaces in the same manner as 
 the anterior and posterior regions. They increase in width from above downward, and 
 
72 OSTEOLOGY, 
 
 form a sort of inclined plane, with a curved surface, and obliquely directed from above 
 downvi^ard, and from within outward. The first two intercostal spaces are both the 
 broadest and the shortest ; the third and fourth are broader in front than behind ; the 
 following are of almost uniform width through their whole extent : on the whole, tue 
 breadth of the spaces diminishes from above downward, or, as Bertin remarks, tlie edge? 
 of the lower ribs are almost in contact. The last two intercostal spaces form the onlj 
 exception, for they are nine lines in width, while those in the middle of the chest are 
 only about four. It should, moreover, be remarked, that the intercostal spaces are 
 broader in front than behind ; a fact which may be easily shown by comparing the dis- . 
 tance which separates the anterior extremities of the first and second ribs with that 
 which intervenes between their posterior terminations. The length of the intercostal 
 spaces increases from the first to the sixth ; it then diminishes to the last two, where it 
 is very small. 
 
 Internal Surface of the Thorax. 
 
 This surface, like the external, is divided into four regions. The anterior region ex- 
 actly resembles the anterior region of the external surface, with this difference only, 
 that it is concave instead of being convex. 
 
 • The -posterior region presents, 1. In the median line, the dorsal portion of the spinal 
 coliuntm, which, like an incomplete septum, forms a projection in the interior of the tho- 
 racic cavity, and divides it into two equal parts ; 2. On the sides, two deep grooves, 
 which are contracted above, but gradually enlarge towards the lower part. These 
 grooves, which lodge the posterior convex portions of the lungs, exist only in the human 
 subject ; they allow part of the weight of the body to be throwTi backward — an arrange- 
 ment which is very advantageous for preserving the equilibrium in standing, and is a 
 proof that man is destined to the erect posture. 
 
 The lateral regions form an inclined plane on the inside, resembling that which exists 
 on the outside, only they are concave instead of being convex. 
 
 Superior and Inferior Circumferences. 
 
 The superior circumference or summit is narrow in comparison with the inferior, and 
 slopes obliquely from above downward and forward ; it is wider transversely than in 
 the antero-posterior direction, and resembles the shape of a heart on playing cards. The 
 circumference of this opening is formed, in front, by the upper end of the sternum ; be- 
 hind, by the first dorsal vertebra ; on the sides, by the first ribs and their cartilages. 
 This opening, which is contracted in its dimensions by the clavicles, gives passage to 
 the following organs : the trachea, the oesophagus, the thoracic duct, the large arteries 
 and veins of the head, neck, and thoracic extremities, the apex of the lungs, and several 
 muscles of the neck. 
 
 The inferior circumference or hase is very wide, at least four times larger than the pre- 
 ceding, and, like it, broader transversely than from before backward. It presents, 1. In 
 front, a wide notch, the borders of which are formed by the cartilages of the seventh, 
 eighth, ninth, and tenth ribs, but are incomplete between the tenth and eleventh, as also 
 between the eleventh and twelfth ; at the apex of this notch is the ensiform cartilage. 
 2. Behind, we find on each side of the vertebral column a notch of much smaller dinien- 
 sions than that in front ; it is caused by the great obliquity of the twelfth rib, which 
 forms an acute angle with the spine. The inferior circumference of the thorax is con- 
 nected with muscles by numerous attachments. 
 
 The great mobility enjoyed by the lower aperture of the thorax, which, as we have seen, 
 is subjected to alternate movements of dilatation and contraction, contrasts remarkably 
 with the almost absolute immutability of the superior aperture. The lower opening pre- 
 sents certain varieties in dimension which are observed chiefly during inspiration, or are 
 occasioned by accidental causes of dilatation, such as pregnancy or the accumulation of 
 fluids in the abdominal cavity. This variability of its dimensions has reference to the 
 compressibility and dilatability of the abdominal viscera. Such an alteration at the upper 
 opening would have caused serious inconvenience by compressing the trachea and the 
 vessels. 
 
 General Development of the Thorax. 
 
 The shape and dimensions of the thorax vary considerably at different periods of Ufe ; 
 it is of great importance to be well acquainted with these, because they bear constant 
 relation to changes in the organs contained within the cavity. 
 
 One of the most remarkable characteristics of the fcetal thorax is the predominance of 
 the antero-posterior over the transverse diameter ; at this age we find the sternum very 
 far separated from the spine, and forming a considerable projection in front. This ar- 
 rangement coincides with the largely-developed state of the heart, and an organ denom- 
 inated the thymus gland, which are both situated in the middle of the thorax ; and also 
 with the small size of the lungs, which are situated laterally. Another marked feature 
 in the chest of the foetus is the absence, or, at least, the slight depth, of those grooves 
 which we have described as peculiar to man, and intended to lodge the posterior edge of 
 
THE LIMBS. 73 
 
 the lungs. The absence of these pulmonary grooves produces, as a necessary conse- 
 quence, a want of those external projections on the back of the thorax, which we find in 
 the adult corresponding with the grooves on the interior. These two characteristics, 
 viz., the predominance of the antero-posterior diameter, and the absence of the grooves, 
 both depend on the same cause, viz., the shght degree of curvature of the ribs in the foetus. 
 
 At a more advanced period the curvatures increase, the posterior grooves are gradu- 
 ally developed, the antero-posterior diameter is diminished, and the transverse propor- 
 tionally increased, so that there is less difference in the absolute capacity of the thorax 
 than would at first sight appear, for the differences we have noticed are in a great measure 
 referrible to the comparative predominance of one or other diameter. We should also 
 remark, that in the foetus, the vertical diameter, particularly at the sides, is much shorter^ 
 on account of the unexpanded state of the lungs, and the elevation of the diaphragm by 
 the abdomind viscera. 
 
 The two circumferences likewise present remarkable differences. In the foetus, the 
 superior opening has a greater extent from before backward than transversely, which is 
 precisely the opposite of what is observed in the adult. The inferior aperture is ex- 
 tremely wide in every direction ; and this accords with the large size of many of the 
 abdominal viscera at this age, and particularly of the Uver. 
 
 At birth there is a sudden enlargement of the chest, because the access of air increases 
 the lungs to a double or threefold extent, which, up to this period, were much contract- 
 ed. At puberty, the thorax participates in the great development which the respiratory 
 apparatus undergoes. It is at this time, eiIso, that malformations of this cavity most fre- 
 quently become obvious. In adult age, the thorax still grows, but in an sdmost insen- 
 sible manner. 
 
 In the aged, the different pieces of the sternum become united by osseous union : the 
 cartilages are ossified ; the thorax has a tendency, in some degree, to form only one 
 piece, which does not permit the different parts to move upon one another. 
 
 THE LIMBS. 
 
 The vertebral column alone, in many animals, is the organ of locomotion, and the jaws 
 the organ of prehension ; but all animals so constituted either live in water or crawl on 
 the earth. The vertebral column, however, in man, and in those animals which live in 
 the air, is not constructed in such a way as to allow of the performance of a complete 
 locomotion, and thence the necessity of limbs, which are only connected to the trunk by 
 their superior extremities, and which, along the rest of their length, are completely iso- 
 lated from the body. They are also denominated extremities, because they are the parts 
 which are most distant from the centre of the body. They are four in number : two supe- 
 rior, or thoracic, so called because they are directly connected with the thorax ; and two in- 
 ferior, or abdominal, because they are continuous with the abdominal cavity. These last 
 are intended to support the weight of the body like two pillars, and to transport it from 
 place to place : the thoracic hmbs are intended to seize objects or to repel them. The 
 extremities present in their structure certain general circumstances which are essen- 
 tially characteristic. We shaU particularly notice the following : 
 
 1. As regards their form. The bones of the extremities differ in many respects both 
 from those of the trunk and those of the head. They generally have the appearance of 
 cylindrical and elongated levers, superimposed so as to form a column, the parts of 
 which are movable upon each other. 
 
 2. The continuity of the extremities with the trunk is established by means of osseous 
 zones or girdles, viz., the shoulder for the thoracic limbs, the pelvis for the abdominal. 
 
 3. The bones of the extremities diminish in size and length from the proximal to the 
 distal, or free end. 
 
 4. The nimiber of the bones in the limbs augments as we proceed towards their free 
 extremity. 
 
 5. As a necessary consequence of the augmented number of bones, and of their pro- 
 gressively diminished size, the articulations become more numerous and smaller towards 
 the distal end of the limb. 
 
 The thoracic and abdominal extremities being constructed upon the same fundamental 
 type, we should never forget, in describing them, that they have numerous analogies, 
 while, at the same time, we notice the differences in each which are connected with its 
 peculiar ofiice. 
 
 THE SUPERIOR OR THORACIC EXTREMITIES. 
 
 The Shoulder. — Clavicle. — Scapula. — The Shoulder in general. — Development. — Humerm. 
 
 — Ulna. — Radius. — The Hand. — The Carpus and Carpal Bones. — The Metacarpus an4 
 
 Metacarpal Bones. — The Fingers. — General Development of the Superior Extremities. 
 
 ;, The thoracic extremities arQ divided into four parts, which, proceeding from the central 
 
 Dwards the distal end, are, 1. The shoulder ; 2. The arm ; 3. The fore-ann ; 4. The hand 
 
 K 
 
'i4 OSTEOLOGY. 
 
 ■;„*?r":t The Shoulder. ^mfiX- • ^^ .,» ..J ;..' 
 
 The shoulder, situated at the posterior and lateral part of the chest, is composed of 
 two bones, which form by their union a sort of angular lever with a horizontal and a ver- 
 <ical arm. The horizontal arm is represented by the clavicle ; the vertical, by the scapula. 
 
 The Clavicle {fig. 41). 
 
 The clavicle performs so important an office in the mechanism of the thoracic extrem- 
 Fig.M. ity, that, upon its presence in a certain number of an- 
 
 imals, and its absence in others, the extremely im- 
 portant distinction between claviculated and non-cla- 
 viculated animals has been founded. 
 
 The clavicle, so called from its supposed resem- 
 blance to a key, occupies the superior and anterior part of the thorax, and forms the an- 
 terior portion of the shoulder. It is placed horizontally between the sternum, which is 
 its fulcrum, and the scapula, the movements of which it follows. Its length varies in 
 different individuals, and more particularly in the different sexes ; in the female it is 
 generally longer than in the male. It is a long bone, and forms one of a pair, and is 
 consequently asymmetrical ; its inner end (,e,fig. 41), which is the larger, is rounded ; 
 its outer end (d) is flattened from above downward, and it enlarges progressively from 
 without inward like a cone. Its direction should be carefully studied. Proceeding 
 from its outer end, which is very thin, we find it describing a curve with the concavity 
 forward (d a) ; it then changes its direction, and describes a much larger curve with the 
 concavity looking backward {a c). The clavicle, therefore, has two alternate curvatures, 
 resembling an italic S, an arrangement which has the advantage of giving strength to 
 the bone, since each curve becomes the seat of a decomposition of forces, which greatly 
 diminishes the violence of shocks directed against it from without inward. 
 
 The clavicle may be divided into a body and extremities. 
 
 The body (a) presents two surfaces, one superior and one inferior ; and two borders, 
 an anterior and a posterior. 
 
 The superior surface (a) of the body is placed almost immediately under the skin, and 
 offers an extensive and ill-protected surface to the action of foreign bodies ; this is one 
 of the causes of the great frequency of fractures of this bone. This surface is covered 
 by the skin, the platysma myoides muscle, and numerous filaments of the cervical plexus 
 of nerves.* Hence, direct blows upon the clavicle are accompanied with severe pain, 
 on account of the compression of the nerves of this plexus. We find on this surface, 
 near its inner end, a tubercle for the insertion of the sterno-mastoid muscle ; it has also 
 some inequalities for muscular attachments on the outside. 
 
 The inferior surface, broad externally, and narrow internally, like the preceding, is 
 marked by a groove, running longitudinally, and lodges the subclavian muscle. Near the 
 inner extremity of this surface there is sometimes a facette, which articulates with the 
 first rib, and, on its inferior surface, inequalities for the insertion of the costo-clavicular 
 ligament. Near the outer end there is a very rough tuberosity, and an irregular hne, 
 directed obliquely from within outward and from behind forward : they are both intended 
 for the insertion of strong ligaments which unite the clavicle and the scapula, the coraco- 
 clavicular ligaments. The internal third of this surface corresponds to the first rib, 
 which it embraces and crosses at a very acute angle. The middle third corresponds to 
 the first intercostal space, from which it is separated by the brachial plexus and the ax- 
 illary vessels ; the external third is in relation to the coracoid process and the articula- 
 tion of the shoulder with the arm. 
 
 The anterior border (b), which is thin externally, becomes expanded into a surface to- 
 wards the inner end ; its external third is concave, the two internal thirds are convex. 
 This convexity dlows the clavicle to resist, like an arch, any violence applied directly 
 from before backward. The external third of this border, where it gives insertion to 
 the deltoid muscle, is rough, but the two internal thirds are less uneven. 
 
 The posterior border (c) is concave in its four inner fifths, and convex and rough in its 
 external fifth, for the insertion of the Trapezius muscle. Its relations are very impor- 
 tant ; the subclavian vein runs along it, and it also corresponds to the subclavian artery 
 and the brachial plexus. From this it may be conceived how dangerous fractures of 
 the clavicle might become, if the sharp end of the fragments should penetrate among 
 the nerves or the vessels ; it may also be imagined how depression of the clavicle, by 
 compressing the vessels which are distributed to the upper extremity, may suspend the 
 circulation there ; and, lastly, we can understand how it is easy to apply a hgature to 
 the subclavian artery, by cutting along the middle of the clavicle. There still remains 
 one important relation to be noticed, viz., the propinquity of the apex of the lungs, from 
 which circumstance it becomes possible to ascertain the sonorousness of this portion of 
 the lungs by percussion on the clavicle. 
 
 Extremities. — The external or acromial end (d) of the clavicle is thin, and flattened from 
 * It is uot uncommon to find the body of the clavicle itself traversed by a nerve of the cervical plexus. 
 
THE SCAPULA. 
 
 ire downward ; it presents a very narrow elliptical facette, whicli looks downward 
 and outward, and articulates with a corresponding surface on the scapula. This is the 
 weakest part of the bone ; it lies almost immediately below the skin, and is much expo- 
 sed to external violence, by which it is sometimes broken. 
 
 The internal or sternal end (e), on the contrary, is the thickest and strongest part of 
 the bone, and might with propriety be named the head of the clavicle ; it" articulates 
 - with the sternum, projecting beyond the concave articular surface of that bone in all di- 
 Tections, a circumstance which renders displacement much more difficult. 
 
 There are many varieties both of size and direction in the body and ends of the clav- 
 icle. By inspection of the inner or outer ends of the clavicle, even in the living body, 
 we may judge at once whether the individual has been engaged in a laborious manual 
 employment. I have been able, from the simple circumstance of a marked preponder- 
 ance of size in the inner end of the left clavicle, to declare a priori, and correctly, that 
 the individual on whom I observed it was left-handed. In some clavicles the inner half 
 resembles a quadrangular pyramid. In the female the clavicle is much more slender, 
 and the curvatures are less pronounced, than in the male : the strength and degree of 
 curvature of this bone are proportionate to the laborious and continued exercise of the 
 upper extremity. It may, therefore, be easily conceived how much importance should 
 be attached in forensic medicine to the characters of a bone, the examination of which 
 would of itself be sufficient to determine whether the body to which it belonged were 
 male or female, and whether the person had been engaged in a laborious manual occu- 
 "'pation, or the contrary. 
 
 ' Cannexions. — The clavicle articulates with three bones, the sternum, the scapula, and 
 often with the first rib. 
 
 Internal Structure. — With regard to its structure, the clavicle appears to hold a middle 
 place between the long bones and the ribs ; like the first, in fact, it possesses a medul- 
 lary canal ; but it approaches the structure of the ribs in the contracted dimensions of 
 this canal, and the spongy nature of its ends. In examining many clavicles belonging 
 to the collections of the Faculty of Medicine, I was never able to meet with one that had 
 traces of a medullary canal extending throughout its entire length. 
 
 Development. — The clavicle makes its appearance at a very early period, about the 
 thirtieth or thirty-fifth day ; its dimensions, compared with those of the other bones of 
 the thoracic extremities, present considerable variations at different ages. In the sec- 
 ond month of foetal life, the clavicle has already acquired nearly three lines in length ; at 
 this time it is at least four times the length of the humerus and femur. After the com- 
 mencement of the third month it is not more than half as long again as these bones. 
 At the end of the third month it is still longer than the humerus, which does not exceed 
 it until the fourth month. Lastly, in the foetus at the full period the humerus does not 
 exceed the clavicle in length by more than a fourth, while in the adult it becomes twice 
 as long. 
 
 The clavicle has only one primitive osseous point ; from the age of fifteen to twenty- 
 eight years, a complementary or epiphysary point is developed, under the form of a very 
 thin plate, at the anterior part of the sternal end. 
 
 The Scapula {Jig. 42). 
 
 The scapula, or shoulder blade, forms in man the back part of the shoulder ; in a great 
 number of animals it constitutes the entire shoulder. Placed pig. 42. 
 
 like a sort of shield upon the back part of the thorax, for which 
 it serves as a means of protection against extern2d violence, this 
 bone corresponds with the lateral part of the spine, which it ap- 
 proaches or quits according to the different movements of the 
 upper extremity, to which it affords a movable point of attach- 
 ment. 
 
 The scapula is proportionally larger in man than in the lower 
 animals. It is an asjonmetrical bone, broad, thin, and triangu- 
 lar, presenting two surfaces, three borders, and three angles. 
 
 The anterior or costal surface is moulded, as it were, upon 
 the thorax ; it is concave ; the concavity being named the sub- 
 scapular fossa, is occupied by the sub-scapular muscle. In this 
 we observe ridges directed obliquely from above downward, and 
 from without inward, which receive the insertion of those apo- 
 neurotic layers which divide the substance of the muscle.* In 
 a well-formed subject, this surface should be exactly fitted to 
 the surface of the thorax ; but when the chest is contracted, as 
 m phthisical patients, the scapula does not participate in an equal degree in this alter- 
 
 * The direction of these ridges is not parallel with that of the back part of the ribs, but crosses them at an 
 angle ; proving, in opposition to the opinion of some of the older anatomists, that the ridgres, and t^e depres- 
 sions which separate them, are not the result of pressure exercised bj; the ribs on the antenor surtace of tM 
 scapula. 
 
5^ OSTEOLOGY. 
 
 ation, and there is, consequently, a disproportion and change of relative position, to such 
 a degree that the scapulae fonn a projection behind, and are in some measure detached 
 from the ribs like wings : hence the expression of scapula data, applied to the external 
 aspect of the shoulder-blades in phthisical persons. 
 
 The posterior or superficial surface {fig. 42) is divided into two distinct parts by a tri- 
 angular eminence named the spine of the scapula (a). This spine, situated at the junc- 
 tion of the upper with the three lower fourths of the bone, arises from the posterior sur- 
 face by a thick edge, which traverses the entire breadth of the scapula ; the spine is 
 then directed horizontally backward, outward, and a little upward, and presents for our 
 notice an upper and a lower surface, which form part of the supra-spinous and the infra- 
 spinous fossae ; an external border (c), short, concave, thick, and smooth ; and a posterior 
 border (a), very thick and sinuous, which has at its inner end a triangular smooth sur- 
 face {d), over which the trapezius muscle glides. This border is placed almost imme- 
 diately under the skin, and may be easily traced in the living subject, even in very cor- 
 pulent individuals. It gives attachment below to the deltoid muscle, and above to the 
 trapezius, which is inserted into nearly the whole of its thickness. 
 
 Instead of uniting so as to form an angle, the external and the posterior borders of 
 the spine are continued into a process named acromion (c), (from aKpoQ, the summit, and 
 u^of ), because this process forms the highest point of the shoulder. The acromion then 
 forms a continuation of the spine, which appears to be its root. At the place where the 
 spine is continuous with the acromion, there is a contraction, a sort of pedicle, above 
 which the acromion enlarges, and becomes curved into a triangular arch presenting an 
 anterior and a posterior surface, a superior and an inferior edge, a base and a smiunit. 
 The posterior surface of the acromion is convex and rough, and is separated from the 
 skin by fibrous tissue and a synovial bursa. It gives attachment to the trapezius mus- 
 cle, and to acromio-clavicular Ugament. The anterior surface is concave and smooth, and 
 corresponds to the shoulder-joint. The upper edge has a facette, which articulates with 
 a corresponding surface on the clavicle ; the lower edge is convex and rough ; the sutrv- 
 mit forms the highest point of the shoulder; the base is continuous with the spine ; the 
 narrowness of this base or pedicle of the acromion explains the possibility of fractures 
 at this point. 
 
 The whole of the posterior surface of the scapula, above the scapular spine, forms the 
 supra-spinmis fossa (/), which is narrow at it its outer part, and a little enlarged and 
 shallower at the inner, and is filled by the supra-spinatus muscle. All that is below the 
 spine forms the infra-spinous fossa {g), which is occupied by the infra-spinatus muscle. 
 Towards the outer part, this fossa presents a vertical ridge, which marks off a narrow 
 surface, elongated from above downward, and itself divided by an obUque ridge into two 
 smaller surfaces, the superior (A) of which gives attacliment to the teres minor muscle, 
 and the inferior (i) to the teres major. 
 
 Of the three borders or costa of the scapula, the internal, which is also called the base, 
 posterior costa, vertebral or spinal border (k d I), is the longest of the three in the human 
 subject ; in the lower animals it is the shortest. It is thin, slopes from without inward 
 in the upper fourth of its extent, and from within outward in the three inferior fourths, 
 which gives it an angular form. The spine of the scapula meets the base at this angle {d). 
 
 The superior or cervical border, or superior costa (k r), the shortest and thinnest ; we 
 observe on it a notch (r) of variable size, which is converted into a foramen by means of 
 a ligament, and gives passage to the supra-scapular nerve ; rarely to the vessels of that 
 name. 
 
 The external or axillary border, or inferior costa {s I), is the thickest part of the scap- 
 ula. It is separated from the thorax by an interval, the extent of which determines the 
 depth of the cavity of the axiUa. Its thickness increases from the lower to the upper part, 
 where it terminates in the glenoid cavity. There is a depression (s) from which the 
 long head of the triceps muscle arises. 
 
 Angles. — Two of the three angles of the scapula are intended for the attaclmient of 
 the principal muscles belonging to this bone ; the third enters into the formation of the 
 shoulder-joint. , 
 
 The internal angle {k) is that which approaches most to a right angle. In robust subjects 
 it presents a marked impression for the insertion of the levator anguli scapulae muscle. 
 
 The inferior angle (JL) is very acute, and is marked internally by inequalities for the at- 
 tachment of the serratus magnus. This angle is only covered by the skin and the latis- 
 simus dorsi muscle, and is, consequently, more liable than the other two to fracture from 
 external violence. 
 
 The external or glenoid angle (m) is the thickest part of the scapula ; it is hollowed into 
 an oval cavity, the long diameter of which is vertical, and the small end of the oval up- 
 permost. This cavity, called the glenoid cavity (m) of the scapula, belongs to the shoul- 
 der-joint ; it is supported by a contracted portion (?0 called tlie neck of the scapula, and 
 is surmounted by a strong process (o) named coracoul, from a fancied resemblance to the 
 bill of a raven. This process is directed outward ami forward like a finger in a state of 
 semiflexion ; its lower surface, which looks oiitwanl, lo confmve and smooth,' and is 
 
THE SHOULDER IN GENERAL. 77 
 
 curved to correspond with the head of the humerus ; its upper surface is convex and 
 rough, and articulates with the clavicle. Its summit is rough, and affords attachment 
 to muscles. The coraco-acromial ligament is attached to its posterior border, the fecto- 
 ralis minor muscle and the anterior fibres of the coraco-clavicular ligaments to its ante- 
 rior, while the short head of the biceps and the coraco-brachialis muscles united arise 
 from its summit. 
 
 Connexions. — The scapula is articulated with the clavicle and the humerus. 
 
 Internal Structure. — There is very little spongy substance in the composition of the 
 scapula, as may be well observed in the supra and infra spinous fossae, where we can 
 scarcely make use of a file, without breaking through the very thin lamina of compact tis- 
 sue of which the bone is composed at these points. The spongy tissue occupies the ax- 
 illary border, the spine, the articular angle, the acromion, and the coracoid process. 
 
 Devclopimnt. — The scapula is developed from six points : one primitive for the body 
 of the bone, and five epiphysary or complementary, viz., one for the coracoid process, 
 two for the acromion, one for the posterior border, and one for the inferior angle. 
 
 The osseous point of the body appears towards the end of the second month of utero- 
 gestation, in the infra-spinous fossa, under the form of an irregularly quadrilateral plate 
 of bone, on the surface of which we cannot perceive any vestige of the scapular spine. 
 It is not until the third month that this process becomes apparent ; and at that period 
 the ossification has made so little progress towards the upper part of the bone, that the 
 spine, which subsequently is situated below the upper fourth of the scapula, is then suffi- 
 ciently elevated to project beyond the upper part of that bone. The spine is never devel- 
 oped from a separate point, but sprouts, as it were, from the posterior surface of the bone. 
 
 The osseous point of the coracoid process appears sometimes at birth, but generally 
 during the first year. 
 
 The osseous germ of the base of the acromion process, which has a rounded form, is 
 developed before the fifteenth year. That of the summit of the acromion does not be- 
 come visible until from the fifteenth to the sixteenth year ; that is the time at which the 
 coracoid process is united to the body of the bone. It is very variable in its shape, be- 
 ing sometimes like a narrow band, sometimes forming, by itself, the greatest part of the 
 process. 
 
 The osseous point of the inferior angle of the scapula is developed during the course 
 of the fifteenth year. 
 
 The osseous point of the vertebral border extends along the whole posterior costa as 
 a long marginal epiphysis, analogous to that which we shall afterward describe as exist- 
 ing on the haunch bone. It is not formed till the seventeenth or eighteenth year. 
 
 The union of these different osseous points does not commence until the fifteenth 
 year, at which time the coracoid process becomes joined to the body of the bone. The 
 other points unite at various periods, which have not yet been determined with much 
 exactness. The osseous point of the vertebral border remains the longest separate of 
 all. The union of all these points is not completed until the time when the growth of 
 the body is terminated. 
 
 The Shoulder in general. 
 
 Considered as forming only one piece, the shoulder represents a bony girdle intended 
 to serve as a fulcrum to the upper extremities. This girdle is incomplete in front oppo- 
 site the sternum, and behind in the region of the vertebral column. From this it follows, 
 that the two shoulders are independent in their motions, while the pelvis, which forms an 
 analogous structure for the lower extremities, is a continuous whole, the different parts 
 of which cannot move upon each other. The shoulders are fixed upon the upper part of 
 the thorax, and so greatly increase its apparent dimensions, that the chest, when they 
 are attached, resembles a cone with the base upward, while in its true shape it is a cone 
 with the base below. The shoulder is moulded exactly upon the thorax in front and be- 
 hind ; on the outside it is separated from it by an interval which forms the apex of the 
 axilla. 
 
 The circumstance which principally determines the transverse breadth of the shoul- 
 ders in the female is the length of the clavicle ; in the male, it is the breadth of the 
 scapula. The length of the clavicle and the width of the chest in front and at the upper 
 part, in the female, are evidently connected with the large size of the mammae ; and the 
 greater development of the scapulae in the male evidently corresponds with his greater 
 muscular power. 
 
 General Development of the Shoulder. 
 The development of the shoulder is remarkable for its precocity. For, on the one 
 hand, the considerable length, the well-defined form, and the double curvature of the 
 fcetal claAdcle, at a time when all the long bones are still straight, prove the rapidity with 
 which this part of the skeleton is developed. On the other hand, the size of the scapula, 
 which is already considerable, and the very advanced state of ossification of the part that 
 sustains the glenoid cavity, which enables it very soon to afford a sufficient resistance to 
 
OSTEOLOGY. 
 
 the movements of the humerus, equally concur in demonstrating the same fact. This 
 rapid development cannot be attributed to the near vicinity of the heart and great vessels, 
 because the sternum and the cervical vertebrae, which are still more closely approximated 
 to the centre of the circulation, are proportionally much slower in their ossification. 
 
 The Arm. 
 The Humerus {Jig. 43). 
 The humerus, or bone of the arm, is situated between the shoulder and the forearm, at 
 -^ ^ the side of the thorax. It is the longest and the strongest of all the 
 /*'■ ■ bones of the upper extremity. It is proportionally shorter in individuals 
 "'^^ ^ of the Caucasian or white races than in the Ethiopian, which in them, 
 ^t in this respect, presents some analogy to the ape tribes. Its direction 
 is vertical, that is, parallel to the axis of the trunk, but with some de- 
 gree of obhquity downward and inward. This obliquity is much great- 
 er in the femur, the bone of the lower extremity which corresponds 
 with the humerus. The distance between the humeri is much greater 
 in man than in quadrupeds, corresponding with the different shape of 
 the thorax, which, as we have before observed, is flattened from before 
 backward in the human subject, and laterally in quadrupeds. The hu- 
 merus is not, like the femur, curved as regards its axis, but it presents 
 a very marked curvature of torsion, which gives rise to a remarkable 
 groove, that lodges the deep artery and the radial nerve, as they turn 
 round the bone in a part of their course. 
 
 The humerus is a long, asymmetrical bone, presenting for examina- 
 tion a body (a) and two extremities {b c) ; the upper of these is rounded, 
 and is called the head (b). 
 
 The lower half of the body of the humerus is prismatic and triangular ; 
 the upper is cylindrical. It has three surfaces, an external, an internal, 
 and a posterior ; and three edges, an external, an internal, and an anterior. 
 The external surface {d e) presents, 1. A remarkable muscular impres- 
 sion, shaped like the letter V, with the point turned downward ; this is 
 the deltoid impression {d), and is generally situated below the upper third 
 of the bone, but sometimes at the middle ; 2. The groove of torsion (/), 
 directed obliquely downward and forward, the depth of which is always 
 proportional to the prominence of the deltoid impression, immediately 
 below which it is placed. Below the groove, the external surface (c) 
 looks forward, and is slightly concave, to allow of the origin of the 
 I { brachialis inter nus muscle. 
 
 The internal surface (a) is an oblique plane, looking forward and in- 
 ward ; the brachial artery runs along it, and therefore it is of impor- 
 tance to he well acquainted with the obliquity of the surface, in order that, when it is 
 necessary to compress the vessel, force may be applied in the proper direction. Its up- 
 per part, which looks forward, is broader than the lower, which is turned inward. On 
 this surface we observe, 1. The bicipital groove (g), which will be particularly noticed af- 
 terward ; 2. The principal nutritious foramen {v) of the humerus, which passes down- 
 ward into the interior ;* 3. An obscurely-marked impression for the coraco-brachialis 
 muscle. 
 
 The posterior surface is smooth, round, and much broader below than above ; it is cov- 
 ered by the triceps. 
 
 Of the three edges, the anterior (h i) is a rough ridge, round and blunt below, bifurcated 
 above, so as to form the two borders of the bicipital groove (g), which is one of the lar- 
 gest and deepest of all the tendinous grooves in the body, and lodges the tendon of the 
 long head of the biceps. The two borders of this groove, the external (h) and the inter- 
 nal {k), are very prominent and rough, and afford attachment to powerful muscles ; the 
 former to the peetoralis major, and the latter to the latissimus dorsi and teres major. It 
 should be remarked, that the anterior branch of the V represented by the deltoid impres- 
 sion is blended with the anterior edge of the bicipital groove, and greatly increases its 
 prominence. 
 
 The other two edges of the humerus, viz., the external {d I) and the internal (v r), are 
 olunt, and scarcely distinguishable in their upper two thirds, but sharp and prominent at 
 iheir lower parts, especially the external edge, which curves forward and gives attach- 
 ment to a great number of muscleig. This edge is also interrupted in its course by the 
 groove of torsion. 
 
 The lower or cubital extremity (c) of the humerus is flattened from before backward, 
 with a transverse diameter four times longer than the antero-posterior. It presents a 
 series of eminences and depressions arranged in the same transverse line, viz., counting 
 
 * There are some varieties in the situation of the nutritious foramen. I have seen it on the external, or 
 even posterior surface of the bone. 
 
THE ULNA. 7g^ 
 
 Irom without inward, 1. An exteriml tuberosity (I), called eptcondyle by Chaussier, which 
 forms a continuation of the outer border, and gives insertion to almost all the muscles 
 on the back of the forearm ; 2. The small head (m) of the humerus {humeral condyle of 
 Chaussier), a rounded eminence, bent forward and oblong from before backward. The 
 small head articulates with the radius, and is surmounted in front by a superficial de- 
 pression, intended to receive the rim of the shallow, cup-like cavity on the top of the 
 radius ; 3. An articular furrow (n), extending obliquely from behind forward, and from 
 without inward, and separating the small head from 4. The trochlea (c), or articulur pulley 
 of the humerus, which is also directed from behind forward, and from without inward, ia 
 excavated like the groove of a pulley in its long diameter, and the inner border of which 
 descends much lower than the outer. This trochlea articulates with a corresponding 
 surface on the ulna, and is surmounted in front by a small cavity named coronoid (o), and 
 behind by a much larger depression, the olecranoid cavity. These two cavities, the ante- 
 rior of which receives the coronoid process of the ulna during flexion of the forearm, and 
 the posterior, the olecranon, during its extension, are only separated from each other by 
 a very thin, translucent lamina of bone, which is sometimes perforated, so that they 
 communicate with each other ; 5. The internal tuberosity or epitrochlea (r),* which is bent 
 inward, is much more prominent than the external, forming a projection which can be 
 easily felt under the skin, and gives attachment to almost all the muscles situated on 
 the anterior aspect of the forearm. 
 
 The superior or scapular extremity of the humerus, much larger than the inferior, pre- 
 sents, 1. The head (i), a sphenoidzil eminence, forming about one third of a sphere. It 
 articulates with the glenoid cavity of the scapula, and is bounded in the two upper thirds 
 of its circumference by a circular furrow. The constriction resulting from this furrow 
 has been improperly called the anatomical neck of the humerus (*). The only part which 
 could possibly be considered as the neck, is a portion of the bone which projects on the 
 inner side, and appears to support the head. It is of importance not to confound the 
 circular constriction, which we have mentioned as being called the anatomical neck, 
 with what is denominated the surgical neck (at k), which is nothing more than that slight- 
 ly contracted portion of the bone which supports the whole of its upper extremity. The 
 presence of the anatomical neck of the humerus, and the inclination of the articular sur- 
 face, cause the axis of this surface to form an obtuse angle with the axis of the rest of 
 the bone. 2. Two other eminences, named greater {t) and lesser (u) tuberosities {trochiter 
 and trochin of Chaussier), and which might be called the great and small trochanters of the 
 humerus : they are separated by the bicipital groove. The smaller, which is in front, 
 gives attachment to the sub-scapular muscle ; the larger, which is external, presents 
 three surfaces, each of which gives attachment to a muscle, viz., to the supra spinatus, 
 infra spinatus, and teres minor. 
 
 Connexions. — The humerus articulates with the scapula, the radius, and the ulna. 
 
 Internal Structure. — The two extremities of the humerus are cellular ; the middle is 
 compact. It has a very large medullary canal. 
 
 Development. — The humerus is developed from seven points ; one for the body, two 
 for the upper end, and four for the lower. 
 
 The first osseous point appears in the middle of the bone from the thirtieth to the for- 
 tieth day, in form of a small solid cylinder, which progressively extends towards both 
 extremities. At birth, and during the course of the first year, the extremities are still 
 cartilaginous. The ossific point of the head of the humerus appears at the commence- 
 ment of the second year ; and that of the great tuberosity from the twenty-fourth to the 
 thirtieth month. It has not, in my opinion, been proved that there is any special point for 
 the lesser tuberosity. The ossification of the lower end of the bone commences after that 
 of the upper. At two years and a half, an osseous point is developed, corresponding to 
 the small head or condyle of the humerus ; at seven years, another nodule appears in the 
 epitrochlea ; at twelve years, a third point, which forms the inner edge of the trochlea ; 
 and, lastly, at sixteen years, a fourth point for the epicondyle. 
 
 The two points of ossification of the upper end of the bone unite from the eighth to 
 the ninth year. The four points of the lower end are joined together in the following 
 order : in the twelfth year, the two points of the trochlea ; in the sixteenth year, the troch- 
 lea, the epicondyle, and the small head. The two extremities are united to the shaft 
 from the eighteenth to the twentieth year. The union of the lower end always precedes 
 that of the upper by one year, although the latter first becomes ossified. 
 
 The Forearm. 
 
 The Ulna (jig. 44-). 
 The ulna, or cubitus, so called because it forms the elbow, is situated between the hu- 
 merus and the carpus, on the inner side of the radius, with which it articulates above 
 and below, but from which it is separated in the middle. It is the longer and the lar- 
 ger of the bones of the forearm. When the whole limb is in the vertical position, this 
 
 * Epitrochlea, from M, upon, and rpox'^'O) apuHey. Epicondyle, from ini, upon, and KivSv^oi, an eminence. 
 
OSTEOLOGY. 
 
 Fig 44. 
 
 H 
 
 bone slants a little from above downward and outward. It is a long and 
 asymmetrical bone, much larger above than below, prismatic, triangular, and 
 slightly twisted upon itself: it is divided into a shaft and extremities. 
 
 The body or shaft (o) of the bone is larger above than below, is slightly curv- 
 ed forward, and has three surfaces and three edges. 
 
 The anterior surface (a) is broad above, and becomes gradually narrower to- 
 wards the lower part. On it we observe the nutritious foramen (above a), 
 which penetrates from below upward, i. e., in precisely the opposite direction 
 of the nutritious canal in the humerus. This surface is slightly grooved, and 
 gives origin to the flexor profundus muscle. 
 
 The posterior surface {d) is slightly convex, and is divided longitudinally by 
 a prominent vertical line into two portions, the inner of which is the broader. 
 A second oblique line placed at the upper part forms a triangular space occu- 
 pied by the anconeus muscle. The internal surface is very broad above, and 
 much smaller at its lowef end, which is immediately subcutaneous. It is 
 smooth throughout its whole extent. Of the three edges, the external (e) is 
 the sharpest, especially in the middle ; it commences above, below a small ar- 
 ticular surface, the lesser sigmoid cavity, and is effaced at the lower part of the 
 bone. It gives attachment to the interosseous ligament, a sort of fibrous mem- 
 brane stretched between the radius and ulna. The anterior edge {n fm) is blunt, 
 and is intended for muscular insertions ; towards its lower part it bends slight- 
 ly forward, becomes rough, and terminates in front of a pointed eminence 
 called the styloid process (m) : it commences above by a very marked projec- 
 tion (w) on the inside of an eminence named the coronoid process of the ulna. 
 The posterior edge commences below the olecranon by a bifurcated extremity ; 
 it terminates insensibly towards the lower fourth of the bone ; this edge may be felt be- 
 neath the skin throughout its whole extent. 
 
 The superior or humeral extremity (J) of the ulna presents a considerable enlargement ; 
 it is hollowed in front into a hook-hke cavity, which articulates with the trochlea of the 
 humerus, to the shape of which it is adapted. This cavity, which forms almost half the 
 circumference of a circle, is called the great sigmoid cavity (fi g h) of the ulna, because it 
 has been compared to the letter sigma of the Greek alphabet. It has a vertical branch, 
 which forms the olecranon process (6), and a horizontal one named the coronoid process (/«). 
 There is a sort of constriction at the place (g) where these two branches meet ; this is 
 the weakest point of the upper end of the ulna, and is, consequently, the almost invariable 
 seat of fractures of the olecranon. The olecranon (i), so named from uMvrj, the elbow, 
 and Kpuvov, the head, because it constitutes the most prominent part, or head of the elbow, 
 presents, 1. A posterior surface, smooth above, and rough and irregular below, where it 
 gives insertion to the triceps ; 2. An anterior or articular surface, concave, divided by a 
 vertical ridge into two lateral parts of unequal magnitude ; this is articulated to the troch- 
 lear surface of the humerus ; 3. Two borders, more or less rough in different subjects, 
 which afford attachments to the triceps muscle ; 4. A base, with the constriction we have 
 before described ; 5. The summit, having the form of a curved beak, which is received into 
 the olecranal cavity of the humerus during extension of the forearm. 
 
 The horizontal branch of the sigmoid cavity, or the coronoid process Qi), presents, 1. A 
 rough inferior surface (i), on which the brachiahs anticus muscle is inserted ; 2. A supe- 
 rior surface divided into two unequal parts by a ridge, which is a continuation of that 
 which divides the articular surface of the olecranon ; 3. An internal rough edge (n), bent 
 inward, and giving insertion to the internal lateral ligament of the elbow-joint ; 4. An 
 external edge marked by a smaU cavity, which is oblong from before backward, and 
 slightly concave in the same direction, and is called the lesser sigmoid cavity (Jc) of the 
 ulna, to which the head of the radius is articulated ; below this small cavity is a rough, 
 triangular, and deeply excavated surface, to which the supinator brevis muscle is attach- 
 ed ; 5. An anterior sinuous edge, with a projection or beak, which is received into the 
 coronoid cavity of the humerus during flexion of the forearm. 
 
 The lower extremity of the ulna presents a small rounded enlargement (c), which has 
 been called the head of the ulna. We observe on the outside an articular facette (Z), con- 
 -vex, and elongated from before backward, which is received into a corresponding con- 
 cave surface on the lower extremity of the radius. On the inner side of this head a 
 vertical cylindrical process arises, called styloid process of the ulna (m), the point of which 
 gives attachment to the internal lateral ligament of the wrist-joint. The head of the 
 ulna presents below a smooth surface, which articulates with the cuneiform bone, a 
 movable fibro-cartilage being interposed ; it is separated from the styloid process behind 
 by a groove for the passage of a tendon, and on the inside by a sUght, irregular depres- 
 sion, to which the triangular fibro-cartilage is attached. 
 
 Connexions. — The ulna articulates with the humerus, the radius, and the cuneiform 
 bone. 
 
 Internal Structure. — The shaft of the ulna is compact ; the two extremities are cellu- 
 lar, especially the upper, the olecranon process of which resembles a short bone, both 
 
THE RADIUS. 81 
 
 in form and stmctuvo. Sometimes, even, as Rosenmullcr has observed, this process 
 constitutes really a short bone, entirely separated from the ulna. 
 
 Development. — The ulna is developed from three points ; one for the shaft, and one for 
 each extremity. The osseous point of the body appears first from the thirty-fifth to the 
 fortieth day, or a little later than that of the humeiiis. At birth, the extremities are 
 entirely cartilaginous ; they do not begin to ossify untQ the sixth year, the lower one 
 having the priority. The coronoid process is formed by extension of the ossific point 
 of the shaft. The nodule of the olecranon appears about the seventh or eighth year. 
 The upper extremity is united to the shaft from the fifteenth to the sixteenth year ; the 
 lower, from the eighteenth to the twentieth year. 
 
 The Radius {fig. 45). 
 
 The raiius, so named because it has been compared to the spoke of a wheel, is situa- 
 ted between the hiunerus and the carpus, on the outside of the ulna, to which ^^ ^j 
 it is contiguous above and below, and from which it is separated in the mid- ' „| 
 
 die by the interosseous space. It is somewhat smaller and shorter than the 
 ulna, and has a vertical direction. It is a long and asyiiunetrical bone, pris- 
 matic and triangular in its shape ; its lower end is the larger, and its shaft is 
 slightly curved ; it consists of a shaft and extremities. 
 
 The shaft (o), smaller above than below, presents a slight curvature with 
 the concavity looking inward : this circumstance increases the distance be- 
 tween the radius and ulna, i. e., the interosseous space. It has three surfa- 
 ces, an anterior, a posterior, and an external, and three edges. The anterior 
 surface (o), narrow above and broad below, presents (above o) the orifice of 
 the nutritious canal, which, like that of the ulna, runs upward, or in an oppo- 
 site direction to that of the humerus. It is somewhat grooved, and gives at- 
 tachment to the flexor longus pollicis, and below to the pronator quadratus mus- 
 cles. The posterior surface, also slightly hollowed, gives attachment to sev- 
 eral of the deep-seated muscles on the back of the forearm. The external 
 surface, convex and rounded, is of equal breadth in almost its whole extent, 
 and presents near the middle a rough surface for the insertion of the prona- 
 tor teres. 
 
 Of the three edges, one is anterior, the other posterior, and the third inter- 
 nal : the anterior edge (t r s) is blunt superiorly ; it commences below a marked 
 projection, named the bicipit£d tuberosity, or tubercle of the radius {t) ; from 
 this point it passes obliquely outward, and terminates below, in front of an- 
 other eminence c£dled the styloid process (s) of the radius. The posterior edge, less 
 prominent than the anterior, forms a scarcely perceptible demarcation between the two 
 surfaces which it separates ; it is pretty well marked in the middle of the bone, but 
 hardly distinguishable above and below. The internal edge {t g) is sharp, and has the 
 appearance of a ridge ; it commences below the bicipital tuberosity, and extends to a 
 small articular cavity (^), on the inner side of the lower end of the bone. This edge 
 gives attachment to the interosseous ligament in its whole extent. 
 
 The superior or humeral extremity (m), called also the head of the radius, expands in 
 form of a shallow but regularly-shaped cup, the cavity corresponding with the small head 
 of the humerus, which it partially receives. It is bounded by a circular border with a ver- 
 tical articular surface (»), varying in breadth in different points, being nearly three lines 
 broad on the inside, where it is in contact with the lesser sigmoid cavity of the ulna. The 
 head of the radius is supported by a constricted portion, or neck {w), of a cylindrical 
 form, and five or six lines in length, which is obhquely directed from above downward, 
 and from without inward. At the junction of the neck and body of the radius, on the 
 inside, we see a very marked process, called bicipital tuberosity (t). Its posterior half is 
 rough, where it gives attachment to the tendon of the biceps ; the anterior is smooth, 
 and the tendon of the biceps glides over it before reaching its point of insertion. 
 
 The inferior or carpal extremity {x), which is the largest part of the radius, is irregu- 
 larly quadrilateral. Its lower surface is articular, smooth, concave, irregularly triangu- 
 lar, and divided by a small antero-posterior ridge into two parts : an internal, which ar- 
 ticulates with the semilunar bone of the Avrist, and an external, which articulates with 
 the scaphoid. In the outside of this surface we observe a pyramidal, triangular pro- 
 cess, slightly bent outward ; this is the styloid process (s) of the radius, shorter and much 
 thicker than the styloid process of the ulna, and, like it, giving attachment to one of the 
 lateral ligaments of the wrist-joint. The circumference of this end of the bone exhibits 
 in front some inequcdities, to which the anterior ligament of the wrist is attached ; Se- 
 hind and on th« outside, it is marked by the following tendinous grooves, viz., proceed- 
 ing from without inward, 1. An oblique groove on the external surface of the styloid pro- 
 cess, which shows the trace of a longitudinal division marking out two secondary fur- 
 rows. 2. A groove bounded by projecting edges, and subdivided into two secondary 
 ones by a longitudinal ridge, less elevated than the lateral border. 3. A somewhat deep- 
 Li 
 
6s OSTEOLOGY. 
 
 er groove, also divided into two secondary furrows of unequal dimensions by a ver3f 
 prominent line.* 
 
 On the inside (g-), the lower end of the radius is slightly excavated, to articulate witii 
 the carpal extremity of the ulna. 
 
 Connexion. — ^The radius articulates with the humerus, the ulna, the scaphoid, and 
 semilunar bones. 
 
 Internal Structure. — The two extremities of the radius are cellular, and are covered by 
 a very brittle layer of compact tissue : this is more remarkably the case at the lowei 
 part of the bone, where fractures most usually occur. The shaft is almost entirely form- 
 ed of compact tissue, and has a very narrow medullary canal. 
 
 Development. — The radius is developed from three points, one for the body, and oi «j 
 for each extremity. The osseous point of the body appears some days before that of 
 the ulna : the lower extremity is developed about the second year ; the upper, at nine 
 years. The upper extremity, which is last in beginning to ossify, becomes united to the 
 body of the bone about the twelfth year, while the lower extremity is not joined until 
 from the eighteenth to the twentieth year. 
 
 The Hand {fig. 46). 
 
 The hand is the last part of the upper extremity. Accustomed as we are to admire 
 jvo- 46. the beautiful and perfect organization of the different parts 
 
 of the animal body, we are impressed with the most profound 
 admiration when examining the mechanism of the hand. 
 The organ of touch and prehension, perfoiining functions the 
 most opposite ; those demanding great force, and those re- 
 quiring the greatest delicacy. To enable it to fulfil at the 
 same time functions so different, great solidity and great mo- 
 bility were essential ; and to secure these conditions, it was 
 necessary that it should be formed of a great number of 
 bones. It is composed of twenty-seven bones, exclusive of 
 the sesamoid bones. The hand exists only in man and in 
 the ape ; and its importance is so great, that it has been con- 
 sidered by naturalists as establishing a fundamental charac- 
 ter of the species. Man alone constitutes the class of bima- 
 na ; the apes form the class quadrumana : but in the hand 
 of the ape, compared with that of man, we find great infe- 
 riority. Let us, then, study with the attention it merits this 
 chef-d'auvre of mechanism, which some of the philosophers 
 of antiquity regarded as the distinctive character of man, 
 and even as the source of his intellectual superiority. 
 "Fae hand, considered as part of the skeleton, is composed of five series of small col- 
 umns. Each series consists of four pieces, excepting the outer one, which has three 
 only. The five series of colmnns converge so as to unite with a bony mass, composed 
 of eight bones (a to i) articulated together, and forming by their junction the base of the 
 hand or the wrist. This bony mass is called the carpus. The five columns {k k), next 
 the carpus, have received the name of metacarpal bones ; by their union they form the 
 metacarpus, which corresponds with the palm of the hand : lastly, the columns which 
 succeed to the metacarpus form appendages which are entirely isolated and independent 
 of each other ; these are the fingers, which are distinguished by numerical names of 
 first, second, third, fourth, and fifth, counting from without inward, the hand being su- 
 pine, and the palm turned forward ; they are also known by the following appellations : 
 thumb, index or indicator, middle, ring, and auricular or little finger. Each finger is composed 
 of three small bones, called phalanges {I m n), distinguished also successively, from above 
 downward, by the numerical names of first, second, and third. The third bears also the 
 name of ungual, because it supports the nail ; the thumb has only two phalanges {I n) ; 
 it is also distinguished from the other fingers, by being on a plane anterior to them. 
 
 The form of the hand leads us to consider separately a dorsal, convex surface, the 
 haah of the hand ; an anterior or palmar surface, the palm {fig. 46) ; an external or radial 
 edge {a n), formed by the thumb ; an internal or ulnar edge (c n), formed by the little 
 finger ; a superior, carpal, or anti-brachial extremity ; and an inferior or digital extrem • 
 ity, composed by the ends of the fingers, which, from their unequal length, form a curve 
 wifcli the convexity downward. 
 
 The natural attitude of the hand is that of pronation, i. e., the attitude in which it is 
 placed when the bones of the forearm, instead of being parallel as in supination, are 
 crossed in. puch a manner that the lower part of the radius is in front of the ulna. The 
 
 * In.the descriptiqa of the muscles, we shall point out the tendon which occupies each of there primitive 
 and secondary grooves. All enumerations of this kind, the advantages of which we do not dispute, when the 
 bones and muscles are already known, will find a place in the table at the end of the part devoted to myology. 
 We have noticed liere the muscular insertions, because, instead of burdening the memory, they are useful in 
 fixing the attention uppn tie objects described. 
 
THE CARPUS. 83 
 
 hand is in this position when laying hold of anything, or exercising ihe sense of touch 
 It is only for the convenience of description that we shall suppose the hand to be in the 
 state of supination, and the palm turned forward. We shall be obliged to return to pro- 
 nation, when we draw a parallel between the hand and the foot. 
 The axis of the hand is ahnost the same as that of the fore2irm. 
 
 The Carpus {a to f, Jig. 46.) 
 
 The carpus (from Kapirdc, wrist, Kup-KSLv, to lay hold of) constitutes the bony structure 
 of the wrist ; it is of an oblong form, and almost elliptical transversely. The anterior 
 surface {fig. 46) is concave, and forms a deep groove, in which the tendons of the flexor 
 muscles are lodged. The posterior surface is convex, and in contact with the extensor 
 tendons. They are both traversed by waved lines, which indicate the numerous artic- 
 ulations of the component bones. The upper border is convex, and articulates with the 
 radius and ulna ; the lower is irregular and sinuous, and articulates with the metacarpal 
 hones. 
 
 At each of the two extremities of the ellipse represented by the carpus, we observe 
 two eminences, which form a projection on the anterior aspect, and contribute to aug- 
 ment the depth of the groove which it forms. The two which occupy the outer edge of 
 the wrist are much smaller than those which are situated on its inner border. 
 
 The structure of the carpus is remarkable in this respect ; that in proportion to its 
 size, it presents in a given space a much greater number of bones than any other part 
 of the skeleton. It consists, in fact, of eight bones, and is scarcely one inch in height, 
 and two inches and a half in breadth. These eight bones are arranged in two series, or 
 rows ; an upper proximal or anti-hrachial {ah c d), and a lotcer distal or metacarpal {e i g f). 
 Each of these ranges is composed of four bones ; counting from the external or radial 
 edge towards the internal or ulnar, they are, in the first row, the scaphoid {a), the semi- 
 lunar (i), the cuneiform (c), (or pyramidal), and the pisiform {d) ; in the second row, tra- 
 pezium (e), the trapezoid {i), the os magnum (g), and the unciforme (/). 
 
 I shall not occupy time in describing successively the six surfaces on each of these 
 bones. By simply explaining the law which regulates their configuration, I shall have 
 the double advantage of avoiding prolixity, and of enabhng the student to understand 
 more correctly both their forms and relations. 
 
 Bones of the first or Anti-brachial Range. 
 
 What I have just said of these bones does not apply to the pisiform, which is distin- 
 guished from all the others by particular characters, and merits a special notice. With 
 regard to the rest,* viz., the scaphoid {a), the semilunar {h), and the cuneiform (c), it may 
 be remarked, 1. That they articulate by their upper surfaces with the forearm, forming 
 a sort of interrupted condyle, i. e., one consisting of several pieces, which is received 
 into the cavity formed by the lower end of the radius and ulna. Each of the bones con- 
 tributes to form this condyle, by means of a convex surface ; consequently, the superior 
 surface of the bones of the first rank is articular and convex. 2. They articulate by their 
 lower surfaces with the bones of the second rank, which on the inside oppose to them a 
 large head formed by the os magnum and unciform, and on the outside a shallow con- 
 cavity, which corresponds to the trapezium and the trapezoid. In accordance with this, 
 the lower surface of the first row presents on the one hand a concavity, which receives 
 the head, and on the other a convexity, which corresponds to the cavity. 
 
 Three surfaces, belonging to the scaphoid, the semilunar, and the cuneiform, unite to 
 form the cavity, which receives the head belonging to the second row. There is, there- 
 fore, a broken cavity, i. e., one formed of several pieces. The scaphoid being the largest 
 of the bones of the first row, and corresponding by itself to the most convex part of the 
 head of the second row, is more deeply excavated than the two other bones ; this has 
 given it the form of a boat, whence the name of scaphoid (<7«a0^, a boat). The semilu- 
 nar, which corresponds to the summit of the head, presents from before backward a con- 
 cavity, which has given it its name ; the cuneiform, on the contrary, corresponds to the 
 least convex part of the articular head, and has an almost plane surface. » 
 
 One bone only, the scaphoid, answers to the concavity formed by the trapezium and 
 trapezoides, and it accordingly presents a convex surface at the point of union. There- 
 fore the lower surfaces of the bones of the first row are concave, and the lower surface of the 
 scaphoid is partly concave and partly convex. 
 
 3. The bones of the first row of the carpus unite with each other by plane surfaces ; 
 those of the scaphoid and semilunar, which join, are very small ; the contiguous surfa- 
 ces of the semilunar and the cuneiform are much larger. 
 
 The semilunar and the cuneiform, which occupy the middle of the row, articulate not 
 only with each other, but also with the scaphoid and the pisiform ; and each, therefore, has 
 two lateral surfaces, so that the two middle bones of the row have four artitular facettes. 
 
 * It is neces.sary, in order to follow this description, and obtain from it all the advantage wkich it can afford, 
 to study at the same time an articulated carpus, especially one in which the joints are exposed behind, soma 
 ligaments remaining in front. 
 
"^ 
 
 OSTEOLOGY. 
 
 The scaphoid, which is the outer bone of the first row, articulates internally witn th(6 
 semilunar, but externally it has a projecting process, which may be easily felt under the 
 skin, and which increases the depth of the anterior groove of the carpus. This eminence 
 constitutes the external superior process of the carpus. 4. The bones of the first row 
 forming part of the concavity in front, and of the convexity behind, have their anterior 
 surfaces much smaller than their posterior ; both are rough, and serve for the insertion 
 of ligaments. 
 
 The pisiform (d) is not in the same rank, and has only one articular surface, which 
 unites with the corresponding surface on the cuneiform. The whole of the rest of its 
 surface is intended for the insertion of ligaments and tendons. Its name is derived from 
 its irregularly rounded form. It is placed on a plane anterior to that of the other bones of 
 the first row, and forms the internal superior process, which is the most prominent and 
 the most superficial of aU the processes of the carpus. The pisiform receives above the 
 insertion of the flexor carpi ulnari^ and below allows of the origin of the abductor minimi 
 digiti. It might with propriety be considered as a sesamoid bone. 
 
 Bones of the Second or Metacarpal Row. 
 
 The bones of the second row are much larger than those of the first ; they form, in 
 fact, the support of the metacarpus. In the first row, the outer bone, namely, the sca- 
 phoid, is the larger ; in the second, the two inner bones, viz., the os magnum (g) and 
 unciform (f). 
 
 Superior Surfaces. — We have already stated, that the surface of the second row, which 
 articulates with the first, presents a head and a cavity. The head is formed almost en- 
 tirely by a spheroidal eminence, named head of the os magnum ; this is supported by a 
 (Constricted portion, or neck, below which is the body, the largest part of the bone ; this 
 head of the os magnum is truncated at its inner part, and appears to be completed by a 
 portion of the os unciforme. The concavity presented by the bones of the second row 
 is constituted by two bones, the trapezium (c), situated on the outside of the carpus, and 
 the trapezoid (i), placed between the trapezium and os magnum. 
 
 The inferior surfaces correspond to the bones of the metacarpus. Taken together, 
 these surfaces form a sinuous and angular line, which by itself would seem to prove the 
 impossibility of dislocation of the metacarpus. The trapezium supports the first meta- 
 carpal bone ; the trapezoid the second ; the os magnum the third ; and the os unciforme 
 the fourth and fifth metacarpal bones. 
 
 The posterior surfaces of the bones of the second row form part of the convexity of the 
 carpus ; the anterior surfaces are narrower, and correspond with its concavity. There 
 is a process on the anterior aspect at each extremity of the second row ; the internal be- 
 longs to the unciform bone, and resembles a hook, the concavity of which looks outward, 
 and corresponds with the flexor tendons ; the external belongs to the trapezium, and 
 forms a much less prominent hook than that of the unciform ; on its inside there is a 
 deep oblique groove for the passage of the tendon of the flexor carpi radialis, and it forms 
 the external inferior process of the carpus. 
 
 Lateral Surfaces. — The bones of the second row are joined together by broad plane 
 surfaces, partly articular and partly non-articular. The two middle bones, viz., the tra- 
 pezoid and the os magnum, have each two lateral articular surfaces, inasmuch as they 
 are articulated with each other, and since the os magnum is united to the unciform, and 
 the trapezoid to the trapezium. The extreme bones of this row have only one side ar- 
 ticular. Each of the middle bones, therefore, has four articular surfaces, a superior, an in- 
 ferior, and two lateral ; each of the extreme bones a superior, an inferior, and one lateral 
 
 Development of the Carpal Bones. 
 All the bones of the carpus, without exception, are developed from single points. The 
 ossific points appear very slowly ; all the bones are cartilaginous at birth. Towards the 
 end of the first year, the cartilages of the os magnum and the unciform show a bony 
 point in the centre. The osseous point of the cuneiform appears from the third to the 
 fourth year ; those of the trapezium and semilunar, from the fourth to the fifth ; and 
 those of the scaphoid and the trapezoid, from the eighth to the ninth year. The pisiform 
 does not become ossified until from the twelfth to the fifteenth year ; in fact, it is the 
 latest to ossify of all the bones of the skeleton. 
 
 The Metacarpus (k k\ Jig. 46). 
 
 The five bony columns which rest upon the carpus form the metacarpus ; they are long 
 bones placed parallel to each other, and constructed on the same model, with very slight 
 differences. Together they form a sort of square grating, the intervals of which are 
 larger, on account of the disproportion existing between the size of the middle part and 
 the ends of these bones. These intervals are denominated interosseous spaces, and are 
 occupied by muscles. 
 
 The metacarpal bones are five in number, distinguished by the names of first, second, 
 &c. They are not perfectly uniform, either in situation, length, or shape. The meta- 
 
GENERAL CHARACTERS OF THE METACARPAL BONES. 86 
 
 carpal bone of the thumb, for instance, is situated upon a plane anterior to that which 
 the others occupy ; instead of being parallel, it is directed obliquely outward and do\vn- 
 ward, and hence the interosseous space between it and the second metacarpal bone is 
 triangular. 
 
 This arrangement is connected with the movement of opposition, which is the char- 
 acteristic feature of the hand. The metacarpus presents a palmar or anterior surface. 
 concave transversely, and slightly so from above downward, which corresponds with the 
 falm. of the hand ; a dorsal convex surface, the hack of the hand ; an external or radial edo-e, 
 which is short, obliquely directed outward and downward, and corresponds to the thumb ; 
 an ulnar edge, short and straight, which corresponds with the little finger ; a superior'or 
 carpal extremity, which presents a very sinuous articular line, to fit the opposite surface of 
 the carpus ; and an inferior or digital extremity, formed by five heads, or, rather, condyles, 
 flattened on the sides, and intended to articulate with the corresponding fingers : this 
 lower d^tremity forms a broken articular line ; it is curved, with the convexity doAvn- 
 ward, and the first metacarpal bone does not appear to belong to it. 
 
 General Characters of the Metacarpal Bones. 
 
 The metacarpal bones belong to the class of long bones, having the same form and 
 structure ; each consists of a hody and two extremities. 
 
 The hody is prismatic and triangular, and slightly curved, so as to present a concavity 
 on the palmar, and a convexity on the dorsal aspect. Of the three surfaces of the body, 
 two are lateral, and correspond to the interosseous spaces ; the third is on the back of 
 the hand, and is covered by the tendons of the extensor muscles. Of the edges, two are 
 lateral ; the third is anterior, and corresponds with the palm of the hand. 
 
 The upper or carpal extremity is large, and has five surfaces, an anterior and a poste- 
 rior, for ligamentous insertions, and three articular ; of the three articular surfaces, one 
 is at the end of the bone, and unites with a corresponding surface on a carpal bone ; the 
 two others occupy the sides of the extremity, and unite with corresponding surfaces of 
 the adjoining metacarpal bones. In some metacarpal bones, the lateral facettes are 
 double on each side. It is necessary to distinguish such of these lateral facettes as are 
 intended to unite with bones of the carpus, between which one of the metacarpal bones 
 is, as it were, wedged, from those which are exclusively intended for the articulation of 
 the metacarpal bones with each other. 
 
 The lower or digital extremity resembles a head flattened on the sides, or a condyle ob- 
 long from before backward, with an articular surface of greater extent on the palmar 
 than on the dorsal aspect, i. c, admitting of greater flexion than extension ; it is marked 
 both internally and externally by a depression, behind which is a rough projection for 
 the attachment of lateral hgaments. 
 
 Are there any peculiar characters by which the different metacarpal bones may be 
 distinguished 1 This question we shall now examine. 
 
 Differential Characters of the Metacarpal Bones. 
 
 The first metacarpal bone (t) is distinguished from the others by the following char- 
 acters : it is the shortest and the largest ; its body is flattened in front and behind 
 like the phalanges ; so that at times it has been looked upon as one of those bones. 
 We shall regard it as belonging to the metacarpus, because it is not only united to the 
 other metacarpal bones by the interosseous muscles, but its inferior or digital extremity 
 also has an exact resemblance. At the same time, we must acknowledge that there is 
 a circumstance in its development which tends to establish its analogy with the pha- 
 fanges. The carpal extremity of the first metacarpal bone has a particular form ; it is 
 concave from before backward, and convex transversely, for articulation with the cor- 
 responding surface on the trapezium. The characteristic marks, then, by which the first 
 metacarpal bone may be recognised, are, its shortness, its greater size, the antero-postenor 
 flattening of the hody, the upper articular surface concave and convex in opposite directions. 
 and the absence of lateral articular facettes. 
 
 There are many distinguishing characters of the second, third, and fourth metacarpal 
 bones. I shall content myself with saying, that the second and third are known by 
 their greater length, for they exceed the fourth by the whole of their lower extremity ; 
 they are also about a third larger, and heavier. 
 
 The third metacarpal bone is distinguished from the second by its greater size, and, 
 accordingly, it gives attachment to one of the most powerful muscles of the hand, the 
 adductor pollicis ; it is also known by having two lateral facettes on its upper extremity, 
 while the second has only one. 
 
 The fifth metacarpal bone (k) is the shortest of all, excepting the first, from which it 
 is distinguished by its smaller size. It differs from the fourth, which it most resembles, 
 1. By its shortness. 2. By the presence of an articular facette only on one side of its 
 carpal extremity. 3. By the existence of a very projecting eminence on its inner side, 
 for the insertion of the extensor carpi ulnaris muscle. 
 
m 
 
 OSTEOLOGY. 
 
 Connexions. — The metacarpal bones articulate with each other, with the bones of the 
 carpus, and with the first phalanges of the corresponding fingers. 
 
 Internal Structure. — They have the same structure as other long bones : their extrem- 
 ities are cellular, and the shafts compact, with a small medullary canal. 
 
 Development. — Each metacarpal bone is developed from two points ; one for the body 
 and superior extremity, and one for the lower or distal extremity. The first metacarpal 
 bone, which in many respects resembles the phalanges, is similar also in its mode of 
 development. One of its two points appears in the shaft ; the other in the upper or 
 carpal extremity, which is the reverse of what takes place in the other bones of the 
 same denomination, and is analogous to that of the phjdanges. The ossific point of the 
 body of the metacarpal bone appears from the fortieth to the fiftieth day of fcetal life. 
 At birth the body is almost completely ossified, but the extremities are still cartilaginous. 
 The bony points of the lower ends of the last four metacarpal bones, and of the upper 
 end of the first, do not make their appearance until the third or fourth year. In general, 
 the upper ends of the last four bones, and the lower end of the first, are ossified by an 
 extension of the shaft ; but I have occasionally seen separate germs for each of these, 
 so that every metacarpal bone had three osseous nodules. The union of the lower ex- 
 tremities with the bodies of the four metacarpal bones does not take place until the 
 eighteenth or twentieth year ; and the same is the case with the ossific point of the up- 
 per end of the first metacarpal bone. In those cases where the lower end of the first 
 metacarpal, and the upper ends of the others, are formed from special points, their union 
 takes place at a much earlier period. 
 
 The Fingers {I m n, and I' n'yjig. 46). 
 
 The fingers are the essential organs of prehension, and for this purpose have a length 
 thickness, and mobility that are very remarkable, when we compare them with the toes, 
 which represent them in the lower extremity. Each finger forms a pyramid, composed 
 of three columns placed upon each other ; the base of the pyramid corresponds to the 
 metacarpus, and there are two enlargements or knots at the places where the columns 
 (named phalanges) unite together. The three columns which compose each finger suc- 
 cessively decrease in size, and are known by the numerical appellations of first, second, 
 and third. The first, which articulates with the metacarpus, is also called the metacarpal 
 phalanx (Z I') ; the second, the middle phalanx (m) ; and the third, which supports the nail, 
 the ungual phalanx {n n'). The thumb alone has only two phalanges, an ixngual and a 
 metacarpal. Chaussier has named the phalanges phalange, phalangine, and phalangette, 
 counting from the base to the ends of the fingers. These denominations he has found 
 very serviceable in the methodical designation of the muscles of the fingers. 
 
 The First Phalanx {I I'). 
 
 The first phalanx belongs to the class of long bones, and presents to our notice, 1. A 
 body resembling a half cylinder, cut along its axis, and slightly curved upon itself, so as 
 to present a concavity in front ; the dorsal surface is cylindrical, and covered by the 
 tendons of the extensor muscles ; the anterior surface is slightly channelled for the par- 
 tial lodgment of the tendons of the flexor muscles ; its edges are sharp, and give attach 
 ment to a tendinous sheath, which converts the channel above mentioned into an osteo- 
 fibrous canal for the flexor tendons of the fingers. 2. An upper or mxtacarpal end, trans 
 versely oblong, and presenting a small glenoid cavity for the head of the corresponding 
 metacarpal bone. 3. A lower end, forming an articular pulley. 
 
 Such are the general characters of the first phalanx, but they are modified in each 
 finger. Thus, the phalanx of the middle finger is the longest ; those of the index and 
 ring finger come next. The first phalanx of the thiunb is the largest in proportion to its 
 length ; the first phalanx of the little finger is the most slender ; it is also the shortest, 
 excepting that of the thumb. 
 
 The Second Phalanx (m). 
 
 The second phalanx differs from the first by its smaller size and the shape of its up 
 per end, which forms two concave articular facettes, separated from each other by a 
 projecting line, which runs from before backward ; these are fitted to the trochlea on the 
 lower end of the first phalanx. The edges of this phalanx are thick and rough above, 
 where they give insertion to the tendon of the superficial flexor of the fingers. 
 
 The thumb has no second phalanx. 
 
 The Third Phalanx (n «'). 
 This bone, to which so much importance has been attached in natural history,* sup- 
 ports the horny part with which the ends of the digits in animals are armed, and the 
 nails in man. It is shaped thus : the upper end is transversely oblong, exactly resem* 
 
 * See the interesting memoir of M. Dum6ril, entitled Dissertation sur la demiire Phalange dans Us Mam 
 ndfe.res ; the ungual phalanx presenting different forms, suited to the difterent instincts of the animal. Thi» 
 is BO remarkable, that, from its examination, the family to which the animal belonged may be ascertained. 
 
THE PELVIS. gP 
 
 bling the upper end of the second phalanx ; from this part it contracts like a cone ; sifter- 
 ward it becomes much enlarged and flattened from before backward, and ends with the 
 shape of a horse-shoe, rough in front, where it supports the pulp of the finger, smooth 
 behind, and indented on the edges. The ungual phalanx of the thumb is much larger 
 than that of the other fingers ; that of the middle one is the next in size ; those of the 
 index and ring finger are almost equal, and that of the little finger is the smallest. It is 
 very difficult to distinguish the phalanges of the right from those of the left hand. 
 
 Development of the Phalanges. 
 The phalanges are developed from two points : one for the body and lower end, and 
 one for the upper end. This mode of development is common to the first, second, and 
 third phalanges. The osseous point of the body appears successively in the first, sec- 
 ond, and third phalanges, from the fortieth to the fiftieth day. The order of succession 
 is not subjected to any certain rules. Bony points are found at the same time in the 
 ungual and metacarpal phalanges, and prior to those of the middle phalanges. The os- 
 sific points of the upper ends of the phalanges appear successively in the first, second, 
 and third phalanges some time after birth, from the third to the seventh year. The 
 epiphysary point of the third phalanx is generally developed before that of the second. 
 The epiphyses do not join the bodies of the bones until from the eighteenth to the twen- 
 tieth year. 
 
 General Development of the Superior Extremity. 
 
 The thoracic limb in the foetus and the infant is remarkable for its dimensions, which 
 are proportionally much greater than in the adult. This early development and size are 
 particularly evident when compared with the slow development of the lower limb ; the 
 resulting disproportion is in an inverse ratio of the age, that is, it is greatest in early life. 
 The thoracic limb of the foetus differs from that of the adult in many other respects be- 
 sides dimensions. Thus, the two extremities of the humerus are proportionally much 
 larger, and altogether cartilaginous, though the difference does not appear to me so great 
 as has been imagined. The lower end of the bone is especially remarkable for the size 
 of the small head, which forms a very marked protuberance in front, and projects con- 
 siderably beyond the pulley or trochlea. In the forearm, the upper end of the radius is 
 situated much farther forward than in the adult, which agrees with the position of the 
 small head of the humerus. This circumstance merits careful notice, because it is one 
 of the predisposing causes of dislocation of the head of the radius forward, the ligament 
 which keeps it back being scarcely able to overcome its tendency in that direction. For 
 the same reason, displacements of the head of the radius are much more frequent in the 
 infant than in the adult. 
 
 The carpus, almost completely unossified at birth, is composed of the same number 
 of cartilages as there are bones afterward. The metacarpus, on the contrary, is ossified 
 long before birth, but this rapid development, common to the whole thoracic extremity, 
 is most remarkable in the phalanges. 
 
 Bichat appears to me to have greatly exaggerated the changes which take place in 
 these bones during the progress of age. I am certain that the torsion of the humerus, 
 and the curvatures of the radius and ulna, and also the interosseous space, exist equally 
 in the new-born infant as in the adult, and in almost the same proportions. 
 
 THE INFERIOR OR ABDOMINAL EXTREMITIES. 
 
 The Haunch. — Os Coxce. — The Pelvis. — Development. — Femur. — Patella. — Tibia. — Fibula. 
 — The Foot. — The Tarsus and Tarsal Bones. — The Metatarsus and Metatarsal Bones. — 
 The Toes. — Development of the Lower Extremities. — Comparison of the Upper and Lower 
 Extremities. — Os Hyoides. 
 
 The inferior or abdominal extremity is divided, like the superior, into four parts, viz., 
 the haunch, the thigh, the leg, and the foot. 
 
 Of the Pelvis. 
 We have seen bony arches growing out from the sides of the dorsal portion of the ver- 
 tebral column, to form the thorax. In the same way there grows out from the sacral 
 portion of the column two large bones, which form the walls of the pelvic cavity. These 
 are the ossa innominata or haunch bones. The pelvis forms an appendix to the abdominal 
 cavity, and lodges and protects a number of important organs, viz., a portion of the or- 
 gans of digestion and of the urinary apparatus, and the whole of the internal organs of 
 generation, together with important vessels and nerves. The pelvis transmits to the 
 inferior extremities the weight it receives from the vertebral column. It is formed by 
 four bones, two of which placed behind on the median line, the sacrum and the coccyx, 
 we have already described ; the two placed on the sides, and extending forward to be 
 united on the median line before, the ossa innominata, we shall now examine. 
 
88 
 
 OSTEOLOGY. 
 
 The Os Coxce, or Os Innominatum {figs. 47 and 48). 
 The haunch hone, called also os coxce, from coxa, the haunch, occupies the lateral and 
 anterior parts of the pelvis. It is the largest of all the broad bones of the skeleton. It 
 is asymmetrical, very irregular in its figure, and twisted upon itself, so that it appears to 
 be composed of two portions ; one superior, triangular, shaped like a wing, and flattened 
 from without inward ; the other inferior, and flattened from before backward. These 
 two parts are united by a contracted portion. On this bone we have for consideration 
 an external or femoral surface, which corresponds with the thigh, an internal or pehic 
 surface, and a circumference. 
 
 On the femoral surface (fig. 47) we observe the following parts : On the contracted 
 Fig. 47. portion, which unites the upper and the lower 
 
 half of the os coxae, is the cotyloid cavity {a. Jigs. 
 47, 48) (from Korvlrj, a cup), or acetabulum, 
 which receives the head of the femur. This is 
 of a hemispherical shape, and is the deepest of 
 \v all the articular cavities ; it looks obliquely 
 downward, outward, and a little forward, and 
 has a considerable depression (b, fig. 47) at the 
 bottom, on its inner aspect. The margin (c) of 
 this cavity is sharp and sinuous, and presents 
 three notches, or, rather, one notch and two slight 
 depressions, one of which is superior, and the 
 other inferior, and somewhat external. The 
 notch (d) is situated below and on the inside ; it 
 is very deep, and converted into a foramen by a 
 ligament, and gives passage to the vessels which 
 penetrate into the cotyloid cavity. Above and 
 below the acetabulum are two horizontal 
 grooves ; the upper one is superficial, and gives attachment to a fibrous expansion, one 
 of the origins of the rectus femoris ; the lower is deeper, and gives passage to the tendon 
 of the obturator externus. Above the cotyloid cavity, the os coxse presents a broad tri- 
 angular surface, improperly called external iliac fossa (c). On it we observe, proceeding 
 from behind forward, 1. A convexity : 2. A concavity, occupying about two thirds of the 
 fossa, and on which the principal nutritious foramina are situated : 3. A second convex- 
 ity : 4. A slight concavity. 
 
 The external iliac fossa is traversed by two curved lines for muscular insertions ; one 
 posterior, called the superior semicircular line (/) ; the other anterior, and much more 
 extensive, the inferior semicircular line (g). All the whole surface behind the former 
 gives attachment to the gluteus maximus : the portion comprised between the two lines 
 gives attachment to the gluteus medius. 
 
 Below the acetabulum we observe proceeding from without inward, 1. The obturator 
 foramen (h, figs. 47 and 48), improperly so called ; it is placed more internally than the 
 acetabulum, and has an oval form in the male (hence its name, foramen ovale) : in the 
 female it is smaller, and triangular. Its longest diameter is vertical, and it slopes a lit- 
 tle downward and outward. At its upper part is the obturator groove {i,fig. 48), directed 
 obliquely from behind forward and inward. It gives passage to vessels and nerves, and 
 has two lips : an anterior, which is continuous with the outer half of the circumference 
 of the foramen ; and a posterior, which is continuous with the internal half; for the two 
 halves of the circumference of the obturator foramen, instead of being united in front, 
 pass in different directions, the internal backward, and the external forward, leaving be- 
 tween them an interval which constitutes the groove. 2. On the inside of the obturator 
 foramen is a square surface (k, figs. 47 and 48), broader above than below, oblong in a 
 vertical direction, and rough for the insertion of several muscles of the thigh. This is 
 continuous below with another surface (/, fig. 47), broader inferiorly than above, which 
 extends obliquely downward and outward, then curves upward, and terminates below 
 the cotyloid cavity. This surface, which bounds the obturator foramen below, is intend- 
 ed for muscular insertions. 
 
 The internal or pelvic surface (fig. 48) of the os coxse is concave. It is divided into 
 two parts : a superior, w^hich looks upward, and an inferior, which looks backward, by a 
 prominent horizontal ridge (m n o, fig. 48), which forms the lower boundary of the in- 
 ternal iliac fossa. Above this ridge, which we shall afterward see forms the greatest 
 part of the inlet of the pelvis, we find, proceeding from behind forward, 1. A very prom- 
 inent and rough tuberosity (r), intended for several ligamentous attachments. 2. An ir- 
 regular eirticuiar surface, broader above than below, and called the auricular surface (s) 
 of the OS coxae, from a supposed resemblance to the concha of the ear ; it looks down- 
 ward and inward, and articulates with a corresponding surface on the sacrum. 3. More 
 anteriorly, and on a higher plane, a deep and regular excavation, correctly denominated 
 tne internal iliac fossa (t). This fossa, which is broad and smooth, is occupied by the 
 
THE PELVIS. 89 
 
 iliacus muscle. At its lower part there is a nutritious foramen, which does not corre- 
 spond with that on the outside of the bone. 
 
 Below the horizontal ridge, which divides the internal surface of the os coxa; into two 
 halves, we observe, proceeding from without inward, and from behind forward, l.-A 
 smooth quadrilateral surface, broader above than below, slightly concave, and sloping 
 from above downward, inward, and forward : the front of this surface corresponds to the 
 depression at the bottom of the cotyloid cavity. 2. Behind this surface, a large notch, 
 which will be noticed when describing the circumference of the bone. 3. In front, the 
 inner opening of the obturator foramen, at the upper part of which is the commence- 
 ment of the groove already described. 4. Inside the foramen, a quadrilateral surface, 
 narrower below than above, where it forms a plane, sloping downward and backward, 
 which corresponds to the bladder. 5. Below the same foramen, a smooth surface. 
 
 The circumference of the os coxae is very irregular, and consists of a series of alter- 
 nate projections and notches. We shall describe four borders in this circumference ; a 
 superior, an inferior, an anterior, and a posterior. 
 
 The superior border or crest of the ilium {u v, figs. 47 and 48) is curved like the italic 
 letter iS ; it is directed from before backward, is rough, thick, and convex ; we shall de- 
 scribe it as having two lips and an interstice, that Ave may be able to point out with 
 precision the numerous muscular insertions of which it is the seat. It is not equally 
 thick in its whole extent ; the anterior extremity is thick, it is then contracted a little ; 
 about two inches behind this extremity it is considerably enlarged ; and still more pos- 
 teriorly there is a second enlargement even greater than the former. The inferior bar- 
 ber (w X y, fig. 47), which looks inward, is the shortest ; it commences at the most slo- 
 ping part of the os coxae by a large rough tuberosity, called tuberosity of the ischium (w x), 
 which gives attachment to almost all the muscles on the back of the thigh ; the weight 
 of the body rests upon it in the sitting posture. Proceeding from this tuberosity towards 
 the inner part of the os coxa3 (x y), tlie lower border becomes flexuous, irregular, and 
 shghtly twisted upon itself; it passes obliquely inward and upward, and contributes to 
 form the pubic arch (z y x, fig. 48). Above this oblique portion the border presents a 
 vertical elliptic surface, which unites with the corresponding surface on the opposite 
 bone, and forms the symphysis pubis (y y", figs. 47, 48). The lower border of tlie os coxae 
 consists, therefore, of two portions ; an oblique, which forms part of the arch, and a ver- 
 tical, which forms part of the symphysis. 
 
 The anterior border (u y', figs. 47, 48) commences at the anterior extremity of the crest 
 of the ilium by an eminence for muscular insertion, which can be always easily felt un- 
 der the skin ; it is the anterior superior spinous process of the ilium (m). Below is a notch 
 (m u'), which separates this process from another eminence for the insertion of the rec- 
 tus femoris ; it is caUed anterior inferior spinous process of the ilium {u'). Below this last 
 process is a notch or angular groove {uf n), over which the iliac muscle glides : on this 
 situation the anterior border changes its direction, and, from being vertical, becomes 
 horizontal. The horizontal portion of the anterior border presents then a smooth con- 
 cave surface inclined forward, and shaped like a triangle, with the base outward. This 
 triangular surface, which is covered by the pectineus muscle, presents, 1. An anterior 
 edge (*, fig. 48), continuous with the anterior lip of the obturator foramen. 2. A poste- 
 rior sharp edge, called crest of the pubes (**, figs. 47 and 48), a continuation of the hori- 
 zontal ridge, which we have described as forming the lower boundary of the internal 
 iliac fossa. 3. A base, presenting the cmincntia ileo-pectinea {n n), which corresponds to 
 the femoral artery, and upon which this vessel should be compressed, care being taken 
 to direct the force obliquely downward and backward, that is, perpendicularly to the sur- 
 face of the bone. 4. The summit of the triangle has a sharp eminence, which, in ema 
 ciated subjects, forms a marked projection under the skin. This eminence, called spine 
 of the pubes (o), gives attachment to the rectus abdominis, and must be distinguished 
 from the angle of the pubes (y'), which is a right angle formed by the meeting of the an- 
 terior and inferior borders. 
 
 The posterior border (v w, fig. 48) of the os coxaj commences at the posterior extremi- 
 ty of the crest of the ilium by a sharp eminence, named posterior and superior spinous 
 process of the ilium {v, figs. 47, 48) ; below is a notch, which separates it from another 
 eminence, the posterior inferior spinous process of the ilium {v'). Below this is a very 
 large notch, the sciatic notch of the coxa (v z, fig. 47), which contributes to form the great 
 sciatic notch, which we shall notice in the general description of the pelvis. This notch 
 is terminated below by a sharp ridge, called the sciatic spine (z) ; as this spine some- 
 times projects inward, can it, as some have imagined, press upon the foetal head when 
 it is clearing the lower outlet of the pelvis ] Between this spine and the tuberosity of 
 the ischium (r w ) is a small but well-marked groove, over which the tendon of the ob- 
 turator internus passes. 
 
 Internal Structure. — Like all broad bones, the haunch bone is composed of spongy sub- 
 stance contained between two laminae of compact tissue ; at the bottom of the acetabu- 
 lum, and in the double concavity of the iliac fossae, it is thin and semi-transparent ; it 
 is thick at the circumference, the crest of the ilium, the upper and back part of the ace» 
 
 M 
 
dP OSTEOLOGY. 
 
 tabulum, the articular portion of the pubes, and more particularly at the tuberosity of 
 the ischium. 
 
 Cminr.xions. — The OS coxae unites with its fellow of the opposite side, with the sa- 
 crum, and with the femiir. 
 
 Development. — The os coxae is developed from three primitive, and five secondary 
 points of ossification. The three primitive points remain distinct until a very advanced 
 period, and therefore botli ancient and modern anatomists have incorrectly described 
 them as separate bones, under the names of ilium, ischium, and pubes. The ilium (1, 
 /iff. 48) comprehends the upper part of the acetabulum, and the broad, curved, and trian- 
 gular surface above it. The pubes (2) comprises, 1. The inner part of the acetabulimi. 
 2. The horizontal, prismatic, and triangular column that bounds the obturator foramen 
 above, and which is called the body of the pubes (/). 3. The vertical descending branch, 
 flattened in front and behind, which bounds the same foramen on the inside, and is call- 
 ed the descending ramus of the pubes (k, jigs. 47, 48). 
 
 The ischium (3, fig. 48) comprises, 1. The lower part of the acetabulum. 2. A verti- 
 cal column, very thick, prismatic, and triangular, which forms the tuberosity below, and 
 bounds the obturator foramen on the outside : this is the body of the ischium (/, figs. 47 
 and 48). 3. An ascending branch, sloping inward, flattened in front and behind, which 
 bounds the foramen below and on the inside, and joins the descending ramus of the 
 pubes ; this is the ascending ramus of the ischium (e, fig. 48). The limits of these three 
 pieces are marked before complete development by three cartilaginous hnes, united like 
 the letter Y, at the bottom of the cotyloid cavity (see fig. 48), which is the place where 
 the three primitive osseous points meet ; and this fact has contributed, in no small de- 
 gree, to establish that law of osteogeny which we noticed in our general remarks, viz., 
 that when an articular cavity exists upon the surface of a bone which is developed from 
 several points, these points always unite in that cavity. 
 
 The following are the complementary points : 1. One at the bottom of the acetabulum, 
 pointed out by M. Serres,* and shaped like the letter Y ; 2. The marginal epiphysis, 
 which occupies and forms the entire length of the crest of the ilium ; 3. The epiphysis 
 of the tuberosity of the ischium, which stretches along the ascending ramus ; 4 and 5. 
 Two epiphyses, which do not seem constant ; one occupies the anterior and inferior spi- 
 nous process of the ilium ; the other, still more rare, occupies the angle of the pubes. 
 
 The ossification of the os coxae commences first in the ilium, in the ischium next, and 
 in the pubes last. The osseous germ of the ilium appears on the fiftieth day, that of the 
 iscliium at the end of the third month, and that of the pubes at the end of the fifth month. 
 At birth, the ossification of the os coxae is not far advanced ; the acetabulum is in a great 
 measure cartilaginous. The ascending ramus of the ischium, the descending ramus of 
 the pubes, and the entire circumference of the ilium, are also cartilaginous. These three 
 pieces are imited together from the thirteenth to the fifteenth year. At the same time, 
 the secondary points of ossification appear, and successively unite with the primitive. 
 This union is completed from the tenth to the twentieth year ; the epiphysis of the crest 
 of the ilium alone remains separate until the age of twenty-two, twenty-four, or even 
 twenty-five years. 
 
 The Pelvis in general. 
 
 The sacrum, the coccyx, and the haunch bones having now been described, we are 
 enabled to study the bony cavity which they concur in forming. It is called the pelvis 
 (fig. 48), and forms for the lower extremities an osseous girdle, analogous to that which 
 the shoulders form for the upper extremities. The pelvis or basin, so named because it 
 has been compared to a vase, is a large, irregular, bony cavity, open above and below, 
 which supports the vertebral column behind, and is itself supported by the thigh bones 
 on the sides and in front. In an adult of ordinary stature, tlie pelvis divides the body 
 into two equal parts. In the foetus the part of the body above the pelvis is much longer 
 than that below ; in adults of large stature, on the other hand, the part below is consid- 
 erably longer than that above. 
 
 The pelvis is symmetrical, but of a very irregular figure ; we may say, upon the whole, 
 that it forms a truncated cone, presenting, 1. An upper part or great pelvis, oval trans- 
 versely, much expanded on each side, and notched in front ; 2. A sort of contracted canal, 
 below this upper part, which is called the little pelvis. When the pelvis is examined in 
 the skeleton, it has not the horizontal position which it presents when resting on the 
 tuberosities of the ischium and the extremity of the coccyx. It is inclined with regard 
 to the axis of the body. The obliquity of the pelvis is not the same throughout, and we 
 have therefore to consider two axes, one for the great and one for the little pelvis. The 
 axis of the great pelvis is directed obliquely downward and backward, and is represented 
 by a line passing from the umbilicus towards the lower part of the curvature of the sa- 
 crum ; the axis of the little pelvis, on the contrary, is directed downward and forward, 
 
 * This point of ossification has been regarded as the vestige of a bone peculiar to marsupial animals, and 
 named marsupial bone ; but this view is incorrect, for, according to Cuvier, this fourth piece is found in mar- 
 supials themselves at the bottom of the cotyloid cavity, whereas the marsupial bone is a superadded portion 
 of the skeleton, which supports the pouch in these animals. 
 
THE PELVIS IN GENERAL. 9t 
 
 and is represented by a line passing from the upper part of the curvatuie of the sacrum 
 through the centre of the lower opening or outlet of the pelvis. From the direction of 
 these two axes, it follows that the line of direction of the pelvis is a curve with the con- 
 cavity forward, and which is pretty correctly represented by the curvature of the ante- 
 rior surface of the sacrum. This sort of incurvation of the pelvis is an anatomical fact 
 of the greatest consequence, not only on account of the important office which this part 
 of the skeleton performs in the mechanism of standing, but also because, without an ac- 
 quaintance with it, it is impossible to understand the mechanism of natural labour, the 
 curved canal of the pelvis being the path which the infant has to traverse in passing out 
 of the cavity. 
 
 The obliquity of the pelvis varies at different ages and in different individuals : it is 
 pretty exactly measured by the prominence of the sacro-vertebral angle. 
 
 In the infant the pelvis deviates greatly from the horizontal direction ; its upper aper- 
 ture looks almost directly forward : in the adult it looks much more upward ; and in the 
 aged it again looks forward, as in the infant, but from a very different cause. In the 
 foetus the superior aperture is turned forward, even when the body is upright : at this 
 age the obliquity of the pelvis is inherent in its form ; but in the aged the pelvis looks 
 forward, because the trunk is curved in the same direction, and tends towards a hori- 
 zontal position as in quadrupeds. Thus in the foetus the pelvis has an obliquity which 
 depends on form ; in the aged the obliquity depends upon attitude. 
 
 The human pelvis is much larger than that of any other animal ; and this larger size 
 is connected with the important office it performs in maintaining the erect posture of 
 the trunk. 
 
 There is no part of the skeleton the form and dimensions of which so readily discrim- 
 inate the sex of the individual ; in the male the height predominates ; in the female the 
 breadth. By comparing the distance between the crests and the anterior and the pos- 
 terior spinous processes of the ilia, and between the obturator foramina, in the two sex- 
 es, we find that the transverse dimensions are much greater in the female ; the same is 
 observed in the antero-posterior dimensions, which may be easily proved by measuring 
 the distance between the symphysis pubis and the sacro-vertebral angle, and the dis- 
 tance between each obturator foramen and the sacro-iliac symphysis on the opposite 
 side. We shoidd add that, in the female, 1. The iliac fossae are larger, and turned more 
 outward than in the male ; hence the prominence of the hips. 2. The crest of the ilium 
 is not so much twisted in form of the italic S. 3. The interval between the symphysis 
 pubis and the acetabulum is greater ; this is partly the cause of the great prominence of 
 the trochanters, and the separation of the femora, which gives the female a peculiar gait 
 in walking. 4. The superior strait or brim is wider in every direction. 5. The tuber- 
 osities of the ischia are more separated, and the symphysis pubis is not so deep. 6. The 
 obturator foramen is triangular. 7. The arch of the pubis is rounded, wider, and more 
 curved, while in the male it is triangular and narrower. 8. The inner edges of the ascend- 
 ing rami of the ischia are prominent, and look less directly downward than in the male. 
 Such are the differences of the pelvis as regards sex ; we see that, for the most part, 
 they may be comprehended in the following proposition : 
 
 The female pelvis exceeds the male in its horizontal diameters ; the male pelvis exceeds the 
 femxde in its vertical diameters. 
 
 Regions of the Pelvis. 
 
 Under this title we shall examine in succession the external and internal surface of 
 the pelvis, the upper circumference or base, and the lower circumference or summit. 
 
 The external surface of the pelvis must be examined in front, behind, and on the sides. 
 
 Anterior Region. — 1. In the median line we observe the symphysis pubis (y y,Jig. 48), 
 varying from fifteen to eighteen or twenty pig. 49. 
 
 lines in length, always longer in the male, 
 and resembling a vertical column. It is ob- 
 liquely directed downward and backward, 
 which direction is peculiar to man; in all 
 other animals, as Cuvier has remarked, it is 
 placed horizontally. 2. On each side we find 
 the descending ramus of the pubes (k), which 
 is irregularly quadrilateral, and gives attach- 
 ment to several muscles. 3. Outside the pu- 
 bic column there is, on each side, the obtu- 
 rator foramen (A). 
 
 Posterior Region. — On this we observe, 1, 
 the ridge of the sacnim in the median line ; 
 2, and on each side the sacral grooves into 
 which the posterior sacral foramina open ; they are much deepened above, because the 
 back part of the ilium projects behind the sacrum : we find here, also, two ranges of 
 eminences, corresponding to the articular and transverse processes, and likewise the 
 back of the sacro-iliac articulation. 
 
«g OSTEOLOGY. 
 
 Each lateral region is formed by the external iliac fossa, the acetabulum, and a con- 
 siderable portion of the body of the ischium below this cavity. 
 
 The internal surface of the pelvis is divided into two parts : an upper, which is much 
 expanded, and constitutes the great or false pelvis ; and a lower, more contracted, named 
 the small or true pelvis. These two portions of the same cavity are separated by a cir- 
 cular prominence, formed in a great measure by the horizontal ridge (m n o), which we 
 have described as constituting the lower boundary of the internal iliac fossae. The 
 whole space circumscribed by this line has been named the brim, superior orifice, or supe- 
 rior strait of the pelvis. 
 
 The great pelvis presents, 1. In front, an extensive notch (m y' u) ; 2. Behind, the sacro- 
 vertehral angle ox promontory of the sacrum (below d) ; 3. And on the sides, the internal iliac 
 fossae (1 and t), which form an inclined plane on each side, fitted to direct the weight 
 of the viscera which rest upon them, inward and forward. 
 
 The small pelvis is a cavity, the apertures of which are contracted, and therefore na- 
 med straits, and the middle portion is expanded, and called excavation. 
 
 We shall, therefore, examine separately its superior opening or upper strait, its infe- 
 rior opening or lower strait, and its middle portion or excavation. 
 
 The superior strait or brim is irregularly circular, and has been compared to an oval, 
 an ellipse, or a curvilinear triangle ; but none of these descriptions can give any correct 
 idea of its shape. The circumference, commencing behind, at the articulation between 
 the sacrum and the fifth lumbar vertebra, is formed by the projection of the anterior 
 edge {g d) of the base of the sacrum, by the horizontal ridge (m n),'on the inner surface 
 of the iliac bones, by the pectineal line (w o), and terminates in the spine of the pubes (o). 
 The superior strait has four diameters, an antero-posterior, a transverse, and two oblique. 
 The antero-posterior or sacro-pubic diameter (d y) is generally four inches in length ; the 
 transverse (m m), which is the longest, is five inches ; and the two oblique {n g), which 
 are measured from the eminentia ilio-pectinea on one side, to the sacro-iliac symphysis 
 on the other, are four inches and a half These measures are taken from a well-form- 
 ed female pelvis, and it is chiefly in the female that they are important, on account of 
 their reference to the process of parturition. In the male, all the diameters of the upper 
 strait are smaller. 
 
 The inferior or perineal strait, inferior orifice or outlet of the small pelvis, presents three 
 deep notches separated by three eminences, so that when the pelvis is placed upon a 
 horizontal plane, it appears to rest, as it were, upon three feet. Of these notches, one is 
 anterior, viz., the arch of the pubes {x y x); the others are lateral, and somewhat poste- 
 rior ; they are the ischiatic notches («' z, fig. 47). The arch of the pubes is angular in the 
 male, but rounded in the female, forming a true arch, which receives the occipital bone 
 of the foetus in the great majority of labours ; it is formed on each side by the ascend- 
 ing ramus of the ischium, the edge of which is somewhat everted, so that the head of 
 the foetus when passing under the arch glides over a sort of inclined plane, instead of 
 being in contact with the edge of the bone. The transverse diameter of the pubic arch 
 near the upper part has been calculated at one inch ; that of the lower part {x x, fig. 48), 
 at three inches. The two lateral notches are formed behind by the sacrum and the 
 cocc)rx ; in front, by the sciatic notch of the os innominatum ; they are therefore called 
 also the sacro-sciatic notches. They are very deep, and reach almost to the superior 
 strait of the small pelvis. Of the three emineiwes which separate the notches, the poste- 
 rior is formed by the coccyx, and the two anterior by the tuberosities of the ischia, which 
 are situated on a lower plane than the first ; from this peculiar arrangement, the whole 
 weight of the body, in the sitting posture, rests upon the tuberosities of the ischia, and 
 not at all upon the point of the coccyx. The diameters of the lower aperture of the 
 pelvis are, in reference to parturition, of equal importance with those of the upper, and 
 have been accurately determined. The antero-posterior diameter, or cocci-pubic, so called 
 because it extends from the symphysis pubis to the point of the coccyx, is four inches, 
 but may be increased to four inches and a half by depression of the coccyx. The trans- 
 verse or bisciatic diameter, which stretches between the tuberosities of the ischia, is four 
 inches, which is invariable ; and, lastly, the two oblique diameters, which extend from the 
 middle of the sacro-sciatic ligament on one side to the tuberosity of the ischium on the 
 other, are also four inches each. These dimensions, which are taken from a well-formed 
 female pelvis, are greater than in the male. 
 
 Excavation. — The excavation or cavity of the true pelvis is formed, 1 . Behind, by the 
 sacrum and coccyx, the concavity of which varies in different individuals, but is gener- 
 ally shallower in the female than in the male. The height of these two bones is four 
 inches and a half; the greatest depth of their concavity from ten to twelve lines. 2. In 
 front, by the symphysis and back part of the pubes, forming a plane inclined downward 
 and backward ; outside the pubes is the inner opening of the obturator foramen. 3. On 
 the sides, the excavation is formed by two smooth planes inclined downward and in- 
 ward ; they are about three inches and a half in height, and are bounded behind by the 
 sciatic notch. 
 
 It is of great consequence to notice these two inclined planes, because they perform 
 
THE FEMUR. ffj 
 
 an importcint part in the mechanism of parturition. The diameters of the excavation 
 being of little value in an anatomical point of view, the student is referred to works on 
 midwifery for an account of them. 
 
 The superior circumference or base of the pelvis looks forward, and is formed behind by 
 the sacro- vertebral angle ; on each side by the upper border of the ilium, and in front by 
 the anterior border of the same bone. It presents, 1 . In front, a vast notch {u u, fig. 48), 
 in which we observe in the median line the upper part of the symphysis pubis («') ; on 
 each side, proceeding from within outward, the spine of the pubes (o), the pectineal sur- 
 face (o n), the ilio-pectineal eminence (« w), and the angular groove for the psoas and 
 iliacus muscles (n u"). In all this extent the notch is horizontal, but beyond the groove 
 it slants obliquely upward and outward, to the anterior superior spinous process of the 
 ilium (u), where it terminates. 2. Behind, the great circumference of the pelvis presents 
 the sacro-vertebral angle, and on each side a small notch between the vertebral column 
 and the back of the crest of the ilium. 3. Laterally, we observe the crest of the ilium 
 (m v), bent much more outward in the female than in the male. 
 
 The dimensions of the upper circmnference of the pelvis, measured in a well-formea 
 female, are the following : 1. Between the anterior superior spines of the ilia, from eight 
 to nine inches. 2. From the middle of the crest of one ilium to that of the other, from 
 nine to ten inches. 
 
 The inferior circumference of the pelvis forms the lower strait, which has been already 
 described. 
 
 General Development of the Pelvis. 
 
 The pelvis in the first periods of life participates in the slow development of the lower 
 extremities. Its dimensions, especially in the foetus and in infancy, are so small, that 
 it is unable to receive into its cavity many of the organs which are afterward contained 
 in it ; this is one of the principal causes of the prominence of the abdomen of the foetus. 
 The smaller capacity of the pelvis results also from the absence of the iliac fossae, for 
 these bones are neither twisted nor excavated, but straight and flat. Nevertheless, the 
 upper or iliac portion of the pelvis is proportionally more developed than the lower or 
 cotyloid, doubtless because this latter part belongs especially to the lower extremities, 
 and also serves as a protection to the genital organs, both of which are in a rudimentary 
 state in the foetus. If we examine in detail the differences in size, considered only 
 with reference to the various diameters, we shall find that the transverse are very small, 
 because in front the cotyloid cavities are scarcely developed, and all the pubic region is 
 contracted ; and behind, the iliac bones are more closely approximated to each other, on 
 account of the small size of the sacrum. The antero-posterior diameters appear longer, 
 on account of the shortness of the transverse. But the most characteristic feature of 
 the pelvis in the early periods of life is its much greater inclination than in the adult. 
 In the latter, indeed, a horizontal line drawn from the upper part of the symphysis pubis 
 would fall only a few lines below the base of the sacrum, while in the foetus a similar 
 horizontal hue would fall nearer the lower than the upper part of the sacrum. This, as 
 well as the small capacity of the pelvis, is the cause of the forward position of the blad- 
 der, bringing the whole of its anterior surface to correspond with the parietes of the ab- 
 domen, and, consequently, rendering it more easily accessible to instruments introduced 
 above the pubes. 
 
 We have already remarked, that the obliquity of the pelvis in the aged is not of the 
 same kind as that in the foetus ; and we should add here, that there is no change in the 
 relative position of the bladder, which, as in the adult, corresponds to the back of the os 
 pubis. 
 
 The Thigh. 
 
 The Femur {fgs. 49 and 50). 
 
 The femur, or thigh bone, situated between the pelvis and the leg, is the longest and 
 largest bone of the skeleton. It is proportionally larger in man than in any other ani- 
 mal ; this is connected with the ofiice which it performs, of supporting, by itself alone, 
 the weight of the body in standing, and transmitting it to the leg. It is obliquely di- 
 rected downward and inward. This obliquity is greater in the female than in the male, 
 on account of the greater distance between the acetabula. Too great an obliquity is in- 
 jurious both in standing and walking, and constitutes a well-known deformity. 
 
 The femur describes a curve in front and behind, the convexity of which looks for- 
 ward, and leaves a sort of excavation behind, which is occupied by the numerous pow- 
 erful muscles which bend the leg upon the thigh. This curvature, of which the siun- 
 mit is in the middle of the bone, explains why fractures generally occur here. It is 
 generally very great in subjects affected with rickets. Independently of tliis antero- 
 posterior curvature, the femur is slightly twisted upon itself This curvature of torsion 
 seems to me to be connected with the course of the femoral artery, which passes round 
 the shaft of the bone from one surface to the other. Lastly, at its upper part it presents 
 an angular curve, which we shall notice presently. 
 
94 
 
 OSTEOLOGY. 
 
 Like all other long bones, the femur is divided into a body and extremities. 
 
 Of the Body. — ^The body or shaft is prismatic and triangular, with three surfaces and 
 three edges. 
 
 The anterior surface (a, fig. 50) is rounded, and has a cylindrical aspect ; it is broader 
 below than above. 
 
 The internal surface {h, fig. 49) is flat, it becomes much wider below, and then looks 
 backward. The femoral artery corresponds to this surface, and may be compressed 
 upon it towards the middle third of the thigh. 
 
 The external surface (c) is much narrower than the internal, and is slightly excavated 
 throughout its extent. 
 
 Of the three edges, the internal and the external are rounded, and scarcely distinguish- 
 
 Fig. 49. 
 
 Fig. 50. 
 
 able from the surfaces which they separate. 
 The posterior edge {e df), on the contrary, 
 is very rough and prominent, and has, there- 
 fore, been called the linca aspera : it is di- 
 vided into tico lips and an interspace, for the 
 sake of facilitating the description of the 
 numerous muscles to which it gives attach- 
 ment. It is more rough above than below, 
 and is bifurcated at both ends. Of the two 
 branches of the upper bifurcation, the exter- 
 nal (e), extremely rough, is occasionally sur- 
 mounted by a considerable eminence, and 
 prolonged to the large process called great 
 trochanter. The internal branch is less pro- 
 jecting, and terminates on the inside in a 
 smaller eminence called lesser trochanter. 
 The outer branch (/) of the lower bifurca- 
 tion runs towards the outside of the lower 
 extremity of the femur, and terminates in 
 an eminence, below which is a small de- 
 pression, to which the external head of 
 the gastrocnemius is attached. The in- 
 ner branch (g) is nearly effaced at the part 
 where the femoral artery passes over it : 
 below this it appears again, and, like the 
 outer branch, terminates in a well-marked 
 prominence, to which the adductor magnus 
 is attached, and, below it, the inner head 
 of the gastrocnemius. The triangular in- 
 terval, included between the two branches 
 of the bifurcation, corresponds to the popli- 
 teal artery and vein. The nutritious fora- 
 men (Ji) is situated in the linea aspera ; it passes from below upward. 
 
 The superior extremity of the femur forms an obtuse angle with the body, and presents 
 a head, a neck, and two unequal eminences, named trochanters, the greater and lesser. 
 
 The head (i, figs. 49 and 50) is the most regularly spheroidal of all the eminences in 
 the skeleton, and forms nearly two thirds of a sphere. In the middle of it we observe a 
 rough depression (k) of variable dimensions, which gives attachment to the round Uga- 
 ment. The neck (/), so called because it supports the head of the bone, is obliquely di- 
 rected upward and inward ; it forms an obtuse angle with the body of the femur {angle 
 of the femur), retiring on the inside and projecting on the outside, the degree of which 
 varies in different individuals, at different ages, and in the two sexes. In fact, it is 
 sometimes a very obtuse and sometimes a right angle : this last is most common in the 
 female, and is one of the causes of the prominence in her of the great trochanter. The 
 neck, which varies in length in different subjects, is flattened in fi-ont and behind, so 
 that its verticed diameter is double the antero-posterior ; hence it has more power in 
 resisting force applied from above downward than from before backward, which is a 
 great advantage, since the causes which would produce fractures are almost always ap- 
 plied in the former direction. The anterior surface of the neck is much shorter than 
 the posterior, which is also slightly concave. The upper edge is very short, and pre- 
 sents a great many nutritious foramina ; the lower edge is about double the length of 
 the upper. The base of the neck is marked by a number of nutritious foramina ; it is 
 bounded in front by some inequaUties ; behind by the great trochanter above, and the 
 lesser trochanter below ; and in the interval between these two, by a projecting ridge, 
 which unites them, and which is called the inter-trochanteric line. Behind, at the root 
 of the great trochanter, there is a deep pit, which weakens the neck of the bone in this 
 situation, fiom which circumstance fractures most generally occur at that point. 
 The great trochanter (m) is situated a little behind, at the outer and upper part of the 
 
THE FEMUR, THE PATELLA. TO 
 
 lemur. It is on a lower level than the head, and nearly in the same axis as the shaft, 
 which it prolongs upward. It is of considerable size, and forms a very marked promi- 
 nence under the skin. It should be carefully studied in its relations, 1. With the crest 
 of the ilium, beyond which it projects on the outside ; 2. With the external condyle of 
 the femur ; 3. With the external malleolus, because these relations constantly serve as 
 a guide, both in the diagnosis, and the reduction of dislocations of the femur, and of frac- 
 tures of the neck or shaft of that bone. The great trochanter, which is intended solely 
 for muscular insertions, is of a quadrilateral figure, flattened from without inward, and 
 presents, 1. An external surface, which is convex, and terminates below in a projecting 
 ridge for the vastus externus, and is traversed by an oblique line running downward and 
 backward, to which the gluteus medius is attached ; 2. An internal surface, on which we 
 find a depression called digital, or trochanteric cavity, where the tendon of the obturator 
 externus is inserted ; 3. A superior border, to which the gluteus minimus, the pyramidalis, 
 and obturator internus are inserted ; 4. An anterior border, which is often surmounted by 
 a large tubercle, gives attachment to the vastus externus ; and, 5. A posterior border, which 
 gives attachment to the quadratus femoris. 
 
 The lesser trochanter (n) is situated on the inside, behind, and below the base of the 
 neck of the femur ; it is a sort of conoid tubercle, and gives attachment to the common 
 tendon of the psoas and iliacus muscles. 
 
 The lower end of the shaft of the femur is of considerable size ; it is broad, transverse- 
 ly flattened in front and behind, and divided into two convex articular processes, called 
 internal (r) and external (*) condyles of the femur. The external condyle is in the same 
 line as the shaft of the femur. The internal condyle projects on the inside of the axis 
 of the bone, and below the external condyle, so that when both condyles rest on the 
 same horizontal plane, the femur is directed obliquely downward and inward. The two 
 condyles are separated behind by a deep notch, called inter-condyloid notch (o, fig. 49) ; in 
 front their union forms a sort of pulley, the femoral trochlea {t, fig. 50), on which the pa- 
 tella rests. That portion of the trochlea which belongs to the external condyle is larger, 
 more prominent, and higher than that which belongs to the internal. Each condyle has 
 three surfaces : 1. The lower surface, articular, convex, and rounder behind than in front, 
 is in contact with the tibia and the patella ; the lower surface of the internal condyle is 
 more prominent behind than that of the external. 2. The internal surface of the external 
 condyle, and the external surface of the internal condyle, are deeply excavated, and give 
 insertion to the crucial ligaments. 3. The internal surface of the internal condyle and the 
 external surface of the external condyle present two enlargements, called tuberosities of 
 the femur. 
 
 The internal tuberosity (v) is the larger, and has behind a depression situated above the 
 tubercle for the adductor magnus, already described. The external tuberosity {w) is less 
 prominent, and presents two depressions separated by a tubercle, which may be easily 
 felt under the skin in emaciated subjects. The inferior groove is distinctly marked, and 
 gives origin to the tendon of the popliteus muscle. 
 
 Connexions. — The femur articulates with the innominatum, which transmits to it the 
 weight of the body, and with the tibia upon which it rests, and is in contact with the 
 patella. 
 
 Internal Structure. — Like all long bones, the femur is compact in its shaft and spongy 
 at the extremities ; its medullary canal is the type of canals of that kind. 
 
 Development. — The femur is developed from five points : of these, three are primitive, 
 viz., one for the shaft, and one for each extremity ; two are epiphysary, one being for each 
 trochanter. A bony point first appears in the shaft, from the thirtieth to the fortieth day ; 
 the osseous germ of the lower extremity is visible in the centre of the cartilage, during 
 the last fifteen days of foetal life. The constancy of the appearance of this point is of 
 great importance in forensic medicine, because its existence proves at once that the 
 foetus has reached the full term. The third point is seen in the head of the femur, at the 
 end of the first year after birth. The neck has no separate osseous centre ; it is formed 
 by an extension of the shaft. The nodule of the great trochanter is developed from three 
 to four years after birth ; that of the lesser trochanter, from the thirteenth to the four- 
 teenth year. 
 
 The order of union of these parts does not coincide with that of their appearance ; it 
 commences after puberty, and does not terminate until after the growth of the body is 
 completed. The lesser trochanter, the great trochanter, and the head, are successively 
 attached to the bone about the eighteenth year. The lower extremity, which appeared 
 first, does not join the shaft until the twentieth year. In old age the spongy tissue is 
 frequently so delicate, that the interior of the neck becomes filled with an adipose tissae 
 Uke the body of the long bones. This explains the frequency of fractures in this situa- 
 tion in advanced age. 
 
 The Patella {jig. 51). 
 The patella or rotula, so named from its rounded shape, resembhng a wheel, is, both 
 from its size, and the functions which it performs, the most important of those bones 
 
96 OSTEOLOGY. 
 
 which have been called sesamoid (from aijadfiT]), on account of their resemblance to the 
 sesamum seed, and which are found in the neighbourhood of various articulations that 
 are subjected to much pressure. It is situated in front of the knee, and is movable 
 when the leg is extended ; but fixed and very prominent when the leg is flexed upon the 
 thigh. Its mobility allows it to escape the injurious effect of external blows, to which 
 it would be subject were it united to the tibia like the olecranon process to the ulna. 
 It is the most variable of all the bones, both in its absolute size, and in the proportion of 
 its different dimensions. It is flattened in front and behind, and presents an interior and 
 a posterior surface, and a circumference. 
 
 The anterior or subcutaneous surface {i,fig. 51) is convex, and covered by a very thick 
 layer of fibrous tissue, intimately adherent to the bone. 
 
 The -posterior ox femoral surface (2, fig.' 51) corresponds exactly to the pulley on the 
 lower extremity of the femur. We observe on it, 1. An articular ridge (x) sloping down- 
 ward and inward, and corresponding to the groove of the trochlea, which presents the 
 same obliquity. 2. On each side of this ridge, a concave articular surface, which is mould- 
 ed upon the corresponding condyle of the femur ; and as the external condyle of the 
 femur is the larger, the external articular surface (y) of the patella is much greater than 
 the internal. From this inequality, it is easy at once to distinguish the right from the 
 left patella. 
 
 The circumference of the patella resembles a curvilinear triangle ; its thick base, di- 
 rected upward, gives attachment to the tendon of the rectus femoris and to the tendons 
 of the extensor muscles of the leg ; and its apex (z), turned downward, and somewhat 
 pointed, gives attachment to the ligamentum patellae. Its sides are thin, and give at- 
 tachment to some aponeurotic fibres ; so that, excepting its posterior surface, wliich is 
 articular, the whole patella is enveloped in fibrous tissue ; a circumstance which is in ac- 
 cordance with its peculiar mode of development, and has an important influence over its 
 reunion when fractured. 
 
 Internal Structure. — Tlie patella is entirely composed of spongy tissue, covered in 
 front by a thin layer of compact substance, which renders it very liable to fracture, and 
 which forms a very remarkable exception to the generality of short bones, in presenting 
 well-marked parallel verticcd fibres. Between these fibres are numerous vascular open- 
 ings. 
 
 Development. — The patella is developed from one point only. In a few rare cases, as 
 Rudolphi has observed, there are several points. The ossification of the patella com- 
 mences about the age of two years and a half 
 
 The Leg. 
 
 The Tibia (fig. 52). 
 
 The tibia, the larger of the two bones of the leg, is situated between the femur, which 
 rests upon its upper end, and the foot on which it is supported. Next to the femur, it 
 is the largest and longest bone of the skeleton. Its upper extremity is expanded ; the 
 shaft is narrower, and of a triangular prismatic form. The lower extremity is also ex- 
 panded, but to a much less degree than the upper. The smallest part of the tibia does 
 not exactly correspond with the middle of the shaft as in the femur, but at the junction 
 of the lower with the two upper thirds ; and in this place fractures, produced by centre- 
 coup, are most frequent. The direction of the tibia is vertical, contrasting thus with the 
 femur, which, as we have seen, slants obliquely downward and inward. In individuals 
 whose thigh bones are very oblique, the tibife have a direction downward and outward. 
 In a well-formed skeleton, the two tibiae are parallel. 
 
 With regard to its axis, the tibia presents a double inflection, so that the upper end is 
 turned outward and the lower slightly inward. When this last inclination is excessive, 
 it gives rise to bowed legs. Lastly, it is slightly twisted at its lower part.* Like all 
 long bones, it is divided into a body and extremities. 
 
 The body or shaft has the figure of a triangular prism ; and this form, which is observ- 
 ed in ahnost all long bones, is in none so marked as in the tibia. We have, therefore, 
 to consider three surfaces and three edges. 
 
 The internal surface (a, fig. 53) is covered at the upper part by the internal lateral lig- 
 ament, and by an aponeurotic expansion (called patte d^oie,f or goose'' s foot) : in the rest 
 of its extent it is immediately under the skin. This superficial situation of the internal 
 surface partly explains the facility with which this bone may be broken by direct violence, 
 and also the frequency of caries, exostoses, and necrosis. It is broad above, and grad- 
 ually diminishes towards the lower part. Its three superior fourths look inward and 
 fo'^ward ; its lower fourth looks directly inward. 
 
 The external surface {b) presents in a great part of its extent, but especially above, a 
 longitudinal excavation, the depth of which corresponds to the size of the tibialis an- 
 
 * The absence of an antero-posterior curvature and the lateral curves in opposite directions, together with 
 its slight torsion, explains the great solidity of this bone. 
 
 t [This patte d'oie consists of the expansion formed by the tendons of the sartorius, gracilis, and semitendi- 
 nogus muscles.] 
 
THE TIBIA. 
 
 97 
 
 ticus, to which it gii'es attachment. Inferiorly, the external surface Fig.5i. Fig.sz. 
 
 of the tibia turns forward (d), and this deviation corresponds with the 
 
 altered direction of several tendons, which are placed at first on the 
 
 outside of the bone, and afterward pass in front of it. There is, in 
 
 fact, a constant reciprocity between alterations in the direction of 
 
 bones, and changes in the course of neighbouring tendons. 
 
 The posterior surface is also broad above, and progressively dimin- 
 ishes downward. On it we oh- 1 ve near the upper part, I. An irreg- 
 ular line, running obliquely downward and inward ; to this line many 
 of the deep-seated muscles on the back of the leg are attached. 2. 
 Above this line a triangular surface covered by the popliteus muscle, 
 which separates it from the popliteal artery. 3. Below the same 
 line, the orifice of the nutritious canal, which runs downward. Into 
 this nutritious canal, which is, perhaps, the largest of any in the long 
 bones, I have seen a nervous twig enter, accompanying the nutri- 
 tious artery. 4. From the oblique line to the lower end of the tibia, 
 the posterior surface of this bone is smooth, of almost uniform di- 
 ameter, and divided throughout its length by a more or less marked 
 vertical line. 
 
 The anterior edge (c c) is placed immediately under the skin, beneath 
 which it may be readily felt ;* its lower fourth is round and blunt, the 
 upper three fourths are sharp, and hence it has been called the crest of 
 the tibia. Its upper part inchnes somewhat outward, its lower part in- 
 ward. 
 
 The external edge (g k) gives attachment to the interosseous liga- 
 ment ; it is bifurcated below, and thus forms the two boundaries of an 
 articular cavity, which we shall notice in describing the lower end of the tibia. The «j- 
 ternal border {f I), much less sharp than the others, affords insertion to several muscles. 
 
 The upper or femoral extremity (/ g) of the tibia is at least double tlie size of the lower, 
 and is larger in a transverse direction than from before backward ; on it we observe 
 two concave articular surfaces, of an oval shape, with their long diameter directed from 
 behind forward. They have been improperly denominated condyles; a more correct 
 name would be glenoid cavities of the tibia. These surfaces, which articulate with the con- 
 dyles of the femur, are not perfectly alike ; the internal is longer, narrower, and deeper 
 than the external. They are separated by a pyramidal eminence surmounted by two 
 sharp tubercles. This eminence, which is called the spine of the tibia (e), is nearer the 
 posterior than the anterior part of the bone. In front and behind this spine are two 
 rough depressions, which give attachment to the crucial ligaments. The glenoid cavi- 
 ties are supported by two considerable enlargements, called tuberosities of the tibia. 
 
 The internal tuberosity (/), larger than the external, presents behind a horizontal 
 groove, into which one of the divisions of the tendon of the semi-membranosus is in- 
 serted. The external tuberosity (g), smaller, but more prominent behind than the internal, 
 presents at its back part a small, almost circular facette, which articulates with a corre- 
 sponding surface on the fibula. The two tuberosities of the tibia are separated behind by a 
 considerable excavation. In front they are separated by a triangular surface, pierced by 
 vascular foramina, and terminating below in an eminence, called anterior tuberosity of the 
 tibia (A). This tuberosity, below which the crest of the bone commences, is rough and 
 prominent below, where it gives attachment to the tendon of the extensor muscles of 
 the leg, ligamentum patellcB,i and smooth above, where it is separated from the same ten- 
 don by a synovial bursa. A projecting line runs outward from this tuberosity, and ter- 
 minates above in a tubercle, which is very prominent in some individuals, and may be 
 easily felt under the skin. It gives origin to part of the tibialis anticus. 
 
 The lower or tarsal extremity (Z k) of the tibia is almost square, having, like the upper, 
 its greatest diameter transversely. We observe on it a quadrilateral articular cavity (i), 
 transversely oblong, broader on the outside than on the inside, and divided by an antero- 
 posterior ridge, into two unequal parts. It articulates wth the astragalus. The circum- 
 ference of this extremity presents, 1. In front, a convex surface (rf), with some inequalities 
 for the insertion of ligaments ; it is in contact with the extensor tendons of the toes. 2. 
 Behind, an almost plane surface, having a shallow depression, which is hardly visible in 
 some subjects, forthe tendon of the long flexor of the great toe, and which must not be con- 
 founded with an oblique groove, situated on the inner side, and which will be described 
 with the internal malleolus. 3. On the outside, a triangular cavity (k), broad and smooth 
 below, narrow and rough in its two upper thirds, which articulates with the fibula. 4. On 
 
 * The superficial sitnation of the antenor edge of the tibia renders it a good guide to surgeons in the diagiuv 
 sis and coaptation of fractures of the leg. It also greatly exposes the bone to injury from external violence. 
 It is not uncommon to find it broken, or, as it were, notched, by a gun-shot. 
 
 t t have seen this tuberosity so large that several practitioners, not familiar in such anatomical variettM, 
 believed it to be an exostosis, and had placed the patient, a lad of 14 years of age, under a course of mercozial 
 frictions. 
 
 N 
 
90 OSTEOLOGY. 
 
 the inside, a thick quadrilateral process, flattened on the outside and the inside, and call- 
 ed the internal malleolus (I). This eminence, which bends inward, forms a marked prom- 
 inence at the lower and inner part of the tibia. When the posterior surface of the tibia 
 is laid upon a horizontal plane, the two tuberosities of the upper end of the bone rest 
 upon that plane, while the internal malleolus advances considerably forward ; it is there- 
 fore upon a plane anterior to that of the internal tuberosity of the tibia : this depends 
 upon the torsion of the lower part of the bone. The internal surface (l) of the malleolus 
 is convex, and is placed immediately under the skin : its external surface forms part of 
 the inferior articular cavity of the tibia. Its anterior edge is rough, and gives attachment 
 to ligamentous fibres ; its posterior edge, which is thicker than the anterior, presents a 
 groove running obliquely downward and inward, and sometimes double, along which the 
 tendons of the tibialis posticus and flexor longus digitorum pass. The base of the mal- 
 leolus, very thick, is united to the shaft of the bone. The summit, which is truncated 
 and slightly notched, gives attachment to the internal lateral ligament of the ankle-joint. 
 
 Connexions. — The tibia articulates with the femur, the astragalus, and the fibula ; it 
 articulates also with the patella, but indirectly by means of the ligamentum patellae. 
 
 Internal Structure. — The shaft consists of compact tissue, and has a large medullary 
 canal. The two extremities are spongy, and are pierced by a great number of vascular 
 foramina. 
 
 Development;. — The tibia is developed from three points ; one for the body, and two for 
 the extremities. Sometimes there are four. Beclard once saw the internal malleolus 
 developed firom a separate point. The ossific point of the shaft is the first to make its 
 appearance ; it commences between the thirty-fifth and fortieth day, almost at the same 
 time as that of the body of the femur ; sometimes it is even earlier, as in one case ob- 
 served by myself The bony germ of the upper extremity makes its appearance gen- 
 erally towards the end of the first year after birth. I have never seen it before birth. 
 The ossification of the lower extremity commences during the second year. The inter- 
 nal malleolus is formed by a prolongation of this extremity. The union of all the parts 
 of the bone is not finished until the period of complete development of the body, that is, 
 from the eighteenth to the twenty-fifth year ; it always commences with the lower ex- 
 tremity, which is the last to become bony. It is of importance to remark, that the su- 
 perior epiphysis of the tibia does not form the whole of the upper end of the bone, but 
 only a sort of horizontal plate which supports the articular cavities ; and the same is 
 true of almost all articular extremities. It should also be observed, that the anterior tu- 
 berosity of the tibia is formed by a vertical prolongation of the plate which forms the su- 
 perior epiphysis. It would oppear, that in some subjects this anterior tuberosity has a 
 distinct centre of development. 
 
 The Fibula (fig. 53). 
 
 The fibula or perone (from irepovri) is so named because, according to Sabatier, it has 
 been compared to a sort of clasp or brace in use among the ancients. 
 
 In order to understand the description of this bone, it is necessary to place it exactly 
 in the position which it occupies in the skeleton.* It is situated on the outside of the 
 tibia below, on the outside and to the back of the same bone above. It is as long as the 
 tibia, but is extremely slender ; it is> indeed, the most slender of all the long bones, and 
 may be at once recognised by this character. Its direction is vertical, with a slight in- 
 chnation outward at its lower part. It is the most twisted on itself of all the long bones, 
 and is a remarkable exemplification of that law of osteology, viz., that the torsion of 
 bones is always connected with the changes of direction of tendons, or vessels. It is divided 
 into a body and two extremities. 
 
 The body has the form of a triangular prism. In order rightly to comprehend its 
 shape, it is necessary to be aware that the muscles which are placed on its external 
 surface above turn round to the posterior aspect below, from which it is easy to under- 
 stand how the four upper fifths of the external surface look outward, and the lower fifth 
 backward. 
 
 The external surface (n) is marked by a deep groove which runs along it, and gives at- 
 tachment to the peroneus longus, and pcroneus brevis. The lower part, which is turned back- 
 ward, is smooth. The internal surface is divided into two unequal parts by a longitudi- 
 nal ridge, to which the interosseous ligament is attached. The portion of the surface in 
 front of the ridge is narrower than the other, being in some subjects not more than two 
 lines in breadth ; it gives attachment to the muscles on the fore part of the leg : the por- 
 tion beliind the ridge is larger, and gives attaclunent to the tibialis posticus. This sur- 
 face becomes anterior at its lower part (o). 
 
 * We have hitherto deemed it unnecessary to indicate the position in which each bone should be studied, 
 Decause a glance at an articulated skeleton would suffice to enable the student at once to place the bones 
 aright. The fibula, however, forms an exception, on account of its remarkable torsion. In order, then, to 
 8t:5y this bone conectly, it is necessary to place the flattened end (u ») downward, taking care that the artic- 
 ular surface on that part be turned inward, and that the thin edge (u) of the eminence which forms this Jow- 
 "r end should look forward. 
 
v >^^' • 
 
 THE FOOT. 
 
 99 
 
 The posterior surface of the fibula is narrow above, and expanded below, where it 
 looks inward, and terminates by a rough part, to which ligaments that unite it to the tibia 
 are attached. The whole of this surface gives attachment to muscles. We observe on 
 it the principal nutritious canal, which passes obliquely downward. This canal is some- 
 times placed on the internal surface of the bone. 
 
 The three edges participate in the deviations of the surfaces. Thus, the miter edge (r) 
 becomes posterior below ; the anterior edge (s) becomes external, and is bifurcated ; the 
 internal edge becomes anterior, and after being thus changed, forms the continuation of 
 the ridge for the interosseous ligament, which we noticed upon the inner surface. 
 
 All the edges give attachment to muscles and aponeurotic processes, and are remark- 
 able for their prominence. 
 
 The superior extremity or head (t) of the fibula presents an articular facette (near t\ 
 slightly concave, which unites with a corresponding surface on the tibia : on the outside 
 are some irregular impressions for the insertion of the biceps muscle, and the externa! 
 lateral Ugament of the knee. At the back part of this head we observe the styloid pro* 
 cess of the fibula (below t) for the tendon of the biceps. 
 
 The lower extremity or external malleolus (w v) passes much below the inferior articu- 
 lar surface of the tibia ; it is longer and thicker than the internal malleolus. It is flat- 
 tened on the outside and the inside, and presents, 1. An external surface (uv), convex 
 and sub-cutaneous. 2. An inlerTial surface, which articulates with the astragalus hy 
 means of a facette, which completes on the outside the sort of mortise fgrjneci by tha 
 union of the lower ends of the tibia and fibula ; below and behind this ^urfeioc is a, deep, 
 rough excavation, which gives attachment to a ligament. .3.^Aji aut^erion ^ige (u) for the 
 insertion of a Ugament. 4. A posterior edge (c), thicker, ■jrarlied by a superficial -groovG 
 for the passage of the tendons of the peronei muscles. t&. A summit, which gives airaclj 
 ment to one of the external lateral ligaments of the ankle-jciu*^. 
 
 Connexions. — The fibula forms the outer part of rh*? le?, and a^liculr.tes with the tibia 
 and the astragalus. ' - > ^ 
 
 Internal Structure. — The shaft is compact, and has a very small medullary canal, and 
 the extremities are spongy. 
 
 Development. — The fibiSa is developed from three points : one for the body, and one for 
 each extremity. The osseous point of the body appears a little after that of the shaft of 
 the tibia, from the fortieth to the fiftieth day. At birth, the two extremities are still car- 
 tilaginous. An osseous point appears in the lower end during the second year ; that of 
 the upper end about the fifth. The extremities are united to the shaft of the bone when 
 the development is completed, viz., from twenty to twenty-five years : the lower end is 
 the first to become joined. 
 
 The Foot {figs. 54, 55, and 56). 
 
 The foot is the part of the lower extremity which is analogous to the hand in the up 
 per. They are both but varieties of the same type of organization, with certain differ- 
 ences which have reference to their respective uses. In the foot, for example, which is 
 intended to support the body, the conditions necessary for solidity are principally mani- 
 fest, while the hand is chiefly remarkable for the mobility of its parts. 
 
 The foot is composed of twenty-six bones, which, by their imion, form three distinct 
 parts, viz., 1. The tarsus (c if, fig. 54), a bony 
 mass, consisting of seven pieces closely articu- 
 lated ; 2. The metatarsus, composed of five sep- 
 arate columns {m m", figs. 54 and 55) ; and, 3. 
 The toes, formed each of three columns (n o r), 
 excepting the first, or most internal, which has 
 only two {71" r"). 
 
 The size of the foot varies in different indi- 
 viduals. It exceeds the hand in thickness and 
 length, but is not so broad. Its direction is 
 horizontal from before backward, and it forms 
 a right angle with the leg, differing much in 
 this respect from the hand, which is in the 
 same line as the forearm. It is flattened from 
 above downward, is hollow below {fig. 56), nar- 
 row behind, where it is of considerable height, 
 and thinner and broader in front, at which part 
 jilso it is digitated. It presents, 1 . A superior 
 or dorsal surface, which is convex, dorsum pedis, 
 ( fig. 54) ; 2. An inferior or plantar surface, which 
 is concave transversely, and likewise in the an- 
 tero-posterior direction, sole of the foot {fig. 55) ; 
 
 3. An internal or tibial edge {fig. 56), which is 
 
 very thick, and corresponds to the great toe ; 4. An external or fibular edge, which corre- 
 
100 OSTEOLOGY. 
 
 sponds to the little toe ; 5. A ■posterior extremity or heel ; 6. An anterxar or digital exttemity. 
 We shall describe in succession the tarsus, the metatarsus, and the '.oes. 
 
 The Tarsus {figs. 54, 55, and 56). 
 The tarsus is an analogous structure to the carpus, but differs from it in forming the 
 Pig^ 56. posterior half of the foot, while the carpus 
 
 only constitutes about a sixth of the hand. 
 Its antero-posterior diameter surpasses by 
 more than double its transverse, precisely 
 the opposite of what obtains in the carpus. 
 It resembles a vaulted arch, the convexity 
 of which (c a j, fig. 56) looks upward, and 
 which is excavated below {d i) both trans- 
 versely and from before backward. The 
 weight of the leg falls upon the smnmit of this arch. This form of the foot is not de- 
 signed merely for securing the advantages derived from the mechanism of arches, but is 
 especially intended to afford a protecting excavation for the organs which could not with 
 impunity be compressed in standing and progression. The posterior and free extremity 
 of the tarsus is narrow, and progressively enlarges forward. 
 
 The tarsus is composed of seven bones, disposed in two rows. The/r«^ or tibial raw 
 iS formed b/'twp bones only, the os calcis (c) and the astragalus (a) ; the second or meta- 
 tarsal row cenoists Qffiv& bones, viz., the scaphoid (g), the cuboid (/), and the three cune- 
 iform bones (i j I). The bo|ies. of the first row, instead of being placed in the same trans- 
 verse line, like those of the, flust, row of the carpus, rest one upon the other. The astrag- 
 iilus'is the oniy JJipne /)f the tarsus which enters into the formation of the ankle-joint. 
 
 ' ' ' ■ " "'■'^o .Fiiist ,cri 'J!iJ)ial Row of the Tarsus. 
 " " ■ ♦ The Astragalus [a). 
 The astragalus is placed below the tibia, above the os calcis, on the inside of the mal- 
 leolar extremity of the fibula, and behind the scaphoid ; it is irregularly cuboid in its fig- 
 ure, is the second largest bone of the tarsus, and heis six surfaces : 1. The superior oi 
 tibial surface (a, fig. 54) is articular, and shaped like a trochlea or pulley, which fits ex- 
 actly to the lower surface of the tibia. In front and behind the trochlea are inequalities 
 for the attachment of ligaments. 2. The inferior or calcaneal surface (a, fig. 55) presents 
 two facettes, separated by a very deep furrow, running obliquely backward and inward, 
 and broadest in front, which gives insertion to a ligament. The facette behind the 
 groove is the larger ; it is concave and oblong in the same direction as the groove. The 
 facette in front is flat, and often divided into two smaller surfaces. Both articulate with 
 the OS calcis. 3. The internal lateral surface {fig. 56) is articular for a considerable por- 
 tion of its upper part, and corresponds to the internal malleolus ; below, there is a rough 
 depression, which gives attachment to the internal lateral ligament of the ankle-joint. 
 4. The exterTud lateral surface is triangular, like the corresponding surface of the external 
 malleolus, with which it articulates. It should be remarked, that both the lateral articu- 
 lar surfaces of the astragalus are continuous with the trochlea or upper surface, without 
 mterruption. 5. The anterior or scaphoid surface is convex, and has been called the head 
 of the astragalus ; it is articular, and continuous, below, with the anterior facette of the 
 lower surface of the bone already described. This head is supported by a contracted 
 portion, or neck (i, fig. 54 and 56), to which ligaments are attached. 6. The posterior 
 surface is very small ; it consists simply of a groove, slanting downward and inward, 
 along which the tendon of the flexor longus poUicis pedis glides. 
 
 The Os Calcis (c). 
 
 The OS calcis, or calcaneum, situated below the astragalus, and at the lower and back 
 part of the foot, is the largest bone of the tarsus. Its form is irregularly cuboid, with 
 the greatest diameter from before backward ; it is flattened transversely. Its size and 
 its length have reference to the double ofl5ce which it serves, of transmitting the weight 
 of the body to the ground, and of acting as a lever for the extensor muscles of the foot. 
 I should remark, that its large posterior extremity forms the heel (d, figs. 55, 56), the 
 horizontal direction of which, in man, is one of the most advantageous arrangements for 
 the vertical position of the body. 
 
 The OS calcis has six surfaces : 1. The superior surface {fig. 54) presents, in front, two, 
 or often three, articular facettes, which correspond with those on the lower surface ol 
 the astragalus. The posterior facette is the larger, convex, and separated from the an 
 terior by a groove, which is shallower than the corresponding one of the astragalus, but 
 follows the same direction backward and inward. The whole of the non-articular por- 
 tion of this surface projects behind the astragalus ; it is flattened on the sides, and slight- 
 ly concave from before backward. Its length varies in different individuals, and is tho 
 cause of the varieties in the projection of the heel. 2. Tlie lower oi plantar surface {fig 
 
THE CUBOID AND SCAPHOID BONES. 101 
 
 55) is rather an edge than a true surface ; it is directed obliquely upward and forward. 
 We observe here, at the back part, two tuberosities, the internal of which is much larger 
 than the external ; both serve as places of insertion for muscles, but their principal use 
 is to support the weight of the body behind, and they essentially constitute the heel (d. 
 Jig. 56) in the human subject. 3. The external surface is superficial, which accounts for 
 the frequency of injuries of this bone on its outside, and explains, also, the ])ossibility of 
 reaching it with surgical instruments. It is convex, and narrow in front, where it pre- 
 sents two superficial grooves separated by a tubercle (s, figs. 54 and 55). These grooves 
 afford a passage to the tendons of the peroneus longus and brevis. On the anterior and 
 superior part of this surface we find, also,'tinother tubercle, which is a guide to the sur- 
 geon in the partial amputation of the foot recommended by Chopart. 4. The internal sur- 
 face {fig. 56) is deeply grooved for the passage of several tendons, and also for the 
 nerves and vessels which are distributed to the sole of the foot. It presents, in front 
 and above, a projecting eminence, like a blunt hook, in a shallow groove, below which 
 the tendon of the flexor longus pollicis pedis glides. This eminence has been called 
 the small process of the os calcis (e, fig. 56), also sustentaculum tali, because the anterior 
 and internal articular surface, which supports the astragalus, is on its upper part. 5. 
 The anterior or cuboid surface is the smallest. It is concave from above downward, and 
 articulates with the cuboid. It is surmounted on the inside by a short projection, direct- 
 ed horizontally forward,* above which the third articular surface for the astragalus is 
 situated when it exists. The whole portion of the os calcis which supports the anterior 
 or cuboid surface bears the name of great process of the os calcis {t,figs. 54 and 55). 6. 
 The posterior surface is shaped like a triangle, with the base downward ; its lower part 
 is rough and irregular, and gives attachment to the tendo Achillis, the upper part, over 
 which the same tendon glides, being smooth and polished like ivory. 
 
 Second Row of the Tarsus. 
 The bones of the second row are five in number : on the outside it is formed by the 
 cuboid alone, but on the inside it is subdivided into two secondary rows ; a posterior, 
 formed by the scaphoid ; and an anterior, composed of the three cuneiform bones. This 
 subdivision of the inner portion of the tarsus, by multiplying the articulations, has the 
 effect of diminishing the violence of shocks, or of pressure upon the foot, especially on 
 the inner side, to which they are principally applied. 
 
 The Cuboid Bone [ffigs. 54 and 55). 
 Tho cuboid, which ranks £is the third bone of the tarsus in point of size, is situated at the 
 outside of the foot, and appears like-a continuation of the great process of the os calcis. It 
 is more regularly cuboid than any of the other tarsal bones, and has six surfaces : 1. The 
 upper or dorsal surface {fig. 54) is covered by the extensor brevis digitorum pedis, and 
 looks somewhat outward. 2. The lower or plantar surface {fig. 55) presents on its fore part 
 a deep groove (/), running obliquely inward and forward, for the tendon of the peroneous 
 longus. Behind this groove, the posterior lip of which is very prominent, are impres- 
 sions for the ligament which connects the cuboid and the os calcis. 3. The posterior or 
 calcaneal surface is sinuous, directed obliquely inward and backward, and adapted to the 
 OS calcis in such a way that there is a mutual reception of the surfaces of the two bones. 
 At the inside of this surface, we observe a process which is directed inward and back- 
 ward, and strengthens the union with the os calcis. It occasionally becomes an obstacle 
 to the disarticulation of the foot, after Chopart's method. 4. The anterior or metatarsal 
 surface looks obhquely inward and forward ; it articulates with the fourth and fifth meta 
 tarsal bones. 5. The internal surface articulates with the third cuneiform bone, and fre- 
 quently also with the scaphoid ; it presents, besides, some impressions for the insertiop. 
 of ligaments. 6. The external surface is rather an edge; its extent from before back- 
 ward scarcely equals half the length of the internal surface. We observe on it the com- 
 mencement of the groove for the tendon of the peroneus longus. 
 
 The Scaphoid {g,Jigs. 54, 55, and 56). 
 The scaphoid or navicular hone, so named from its supposed resemblance to a boat, is 
 situated on the inner side of the tarsus ; it is flattened from before backward, and is 
 thicker above than below, irregularly elliptical, with the long diameter placed transverse- 
 ly. It has two surfaces and a circumference : 1. The posterior surface is concave, and 
 receives, thougn incompletely, the head of the astragalus. 2. The anterior surface pre- 
 sents three articular facettes, which correspond to the three cuneiform bones. 3. The 
 circumference is convex above, inclined inward, and rough for ligamentous insertions. It 
 is much smaller below, where also it gives attachment to ligaments. On the i?iside it 
 presents, at its lower part, a large process, process of the scaphoid (at g), which may be 
 easily felt under the skin, and serves as a guide in performing Chopart's amputation. 
 This process gives attachment to the tendon of the tibialis posticus. It is frequently 
 
 * This small prolongation, which might be called imaZi anterior process of the os calcis, in contradistinction 
 to the one on the internal surface already mentioned, merits notice in the performance of Chopart's operation. 
 
102 OSTEOLOGY. 
 
 very large, and may, and, indeed, has been mistaken for an exostosis of the bone. On 
 the outside the circumference is irregular, gives attachment to some hgamentous fibres, 
 and often presents a small surface which articulates with the cuboid : this surface is 
 continuous with the facettes for the three cuneiform bones. 
 
 The Three Cuneiform Bones. 
 These bones, so named from their shape, are three in number: they are called ^rsf, 
 second, and third, counting from the inside of the foot. Tliey are also distinguished by 
 their size, into the great, middle-sized, and small.* 
 
 The First Cuneiform Bone (t, figs. 54, 55, and 56). 
 The first or internal cuneiform bone is the largest. It is placed on the inside of the 
 others, in front of the scaphoid, and behind the first metatarsal bone. It is shaped like 
 a wedge with the base below, which is precisely contrary to what obtains with the other 
 two. We observe oa it, 1. An internal surface {fig. 56), which is subcutaneous, and 
 forms part of the inner edge of the foot. 2. An external surface, which presents an an- 
 gular articular facette for union with the second cuneiform bone behind, and the second 
 metatarsal bone before ; the non-articular portion of the external surface of the first 
 cuneiform bone is rough, and gives attachment to ligaments. 3. A posterior surface, 
 which is concave, and articulates with the most internal and largest facette on the an- 
 terior surface of the scaphoid. 4. An anterior or metatarsal surface, which is plane, or, 
 rather, shghtly convex, of a semilunar form, the convexity being to the inside, and the 
 greatest diameter vertical ; it is broad below and narrow above, and articulates with 
 , the first metatarsal bone. 5. An inferior surface {fig. 55), which forms the base of the 
 wedge ; it is rough, with a tubercle behind for the attachment of the tibialis anticus. 6. 
 An upper part {fig. 54), which forms the point of the wedge ; it is an angular border, 
 running forward and upward, and thicker in front than behind, where it contributes to 
 form the convexity of the foot. 
 
 The Second or Middle Cuneiform Bone {j,fig. 54, 55, and 56). 
 The second coneiform bone is the smallest of the three : it ^ placed between the two 
 others, and corresponds to the scaphoid behind, and the second metatarsal bone in front. 
 The wedge wliich it represents has the base turned upward ; its length from behind for- 
 ward is very inconsiderable. It presents, 1. An internal surface, which is triangular, and 
 articulates with the first cuneiform bone : 2. An external surface, which articulates with 
 the third or external cuneiform bone : 3. A posterior or scaphoid surface, which is concave, 
 and articulates with the middle facette on the anterior surface of the scaphoid : 4. An 
 anterior or metatarsal surface, which is triangular, and nan'ower than the posterior ; it 
 articulates with the second metatarsal bone : 5. A superior surface {fig. 54), or lase of 
 the wedge, which is irregularly square, and rough for the attachment of ligamentous 
 fibres : 6. An apex {fig. 55), which is very thin, and gives attachment to some hgaments. 
 
 The Third or External Cuneiform Bone {I, figs. 64 and 55). 
 
 This bone, which is the third as regards position, and the second in point of size, has, 
 like the preceding, the form of a wedge with the base turned upward. Its internal sur- 
 face articulates behind with a corresponding surface on the preceding bone, and in front 
 with the second metatarsal. This last portion completes the kind of recess or mortise 
 into which the head of the second metatarsal bone is received ; its inner side being 
 formed by the first cuneiform bone, and the bottom by the second. The external surface 
 articulates with the cuboid : the posterior surface is continuous with the two lateral ones, 
 and articulates with the most external of the three facettes on the scaphoid : the ante- 
 rior surface is triangular, and articulates with the end of the third metatarsal bone : the 
 base {fig. 54) is rough, and forms part of the convexity of the foot : the apex {fig. 55) is 
 more obtuse than the same part of the second cuneiform bone, and passes considerably 
 below it. 
 
 Structure of the Banes of the Tarsus. — The bones of the tarsus present the structure 
 common to all short bones, viz., a mass of spongy tissue surrounded by a layer of com- 
 pact substance. I have remarked, that in some cases of white swelling of the ankle- 
 joint, the OS calcis contained in its interior a cavity analogous to the medullary canal of 
 long bones. This cavity, however, must be looked upon as Edtogether abnormal. 
 
 Development of the Tarsal Bones. — ^With the exception of the os calcis, which has two 
 osseous germs, all the bones of the tarsus are developed from single points. The os 
 calcis first becomes ossified. A bony nodule appears in the centre of its cartilage, about 
 the middle of the sixth month of foetal life, according to most osteogonists ; in the fifth, 
 or even the fourth month, according to others. It is placed much nearer the anterior 
 than the posterior extremity of the future bone. Another osseous germ is formed in the 
 posterior extremity of the os calcis, from the eighth to the tenth year, and is much 
 thicker at its lower than at its upper part. The astragalus is developed from one point, 
 
 * Also, by position, into internal, middle, and external. 
 
THE METATARSUS. 103 
 
 which appeara from the fifth to the sixth month of intra-uterine life. According to Bfe- 
 clard, the cuboid is not ossified until some months after birth ; I have observed the pro- 
 cess to be already commenced in a foetus at the full term. Meckel says that it begins 
 after the eighth month of foetal life. Blumenbach, on the contrary, makes the time of 
 its ossification a year and a half, or two years after birth ; and Albinus, who has been 
 followed in this respect by the generality of anatomists, affirms that in the foetus at the 
 full period, all the bones of the tarsus, excepting the os calcis and the astragalus, still re- 
 main cartilaginous. 
 
 The cuneiform bones are developed in the following order : The first is ossified to 
 wards the end of the first year ; the second and the third appear almost simultaneously 
 about the fourth year ; the os calcis being the only bone of the tarsus which has more 
 than one point of ossification, is also the only bone in which we have to examine the or 
 der of union. The two points which form it are not united until the fifteenth year. 
 
 The Metatarsus {m m'^figs. 54, 55, and 56). 
 
 The metatarsus forms the second portion of the foot. Like the metacarpus, its anal 
 ogous part in the hand, it consists of five long bones, parallel to each other, forming a 
 sort of quadrilateral grating, the intervals of which, called interosseous spaces, are in- 
 creased by the disproportion between the ends and the shafts of the bones. The meta- 
 tarsus presents, 1. An inferior or plantar surface {fig. 55), with a marked transverse con- 
 cavity ; 2. A superior or dorsal surface {fig. 54), which is convex^ and answers to the 
 back of the foot ; 3. An internal or tibial edge (m', fig. 56), which is very thick, and cor- 
 responds to the great toe ; 4. An external or fibular edge, which is thin, and corresponds 
 to the little toe ; 5. A posterior or tarsal extremity, which presents a waved articular line ; 
 6. An anterior or digital extremity, presenting five heads flattened on the sides, which as- 
 sist in forming five separate articulations. The bones of the metatarsus have certain 
 characters which distinguish them from all others, besides some peculiar marks by which 
 they may be known from each other, and from the metacarpal bones, with which they 
 have many analogies. 
 
 General Characters of the Metatarsal Bones. 
 The metatarsal bones belong to the class of long bones, both in shape and structure. 
 Each consists of a body and two extremities. The body is prismatic and triangular, and 
 sUghtly curved, with the concavity below. Two of its surfaces are lateral, and corre- 
 spond to the interosseous spaces ; the third, so narrow that it resembles an edge, is on 
 the dorsum of the foot. Two of the edges are lateral ; the third is below, on the plantar 
 aspect of the foot. 
 
 The posterior or tarsal extremity is much expanded, and presents five surfaces, two of 
 which are non-articular, and three articular. Of the two non-articular surfaces, one is su- 
 perior, and the other inferior ; both give attachment to ligaments. Of the three articu- 
 lar surfaces, one is posterior, that is, on the extremity of the bone ; in general it is tri- 
 angular, and articulates with a corresponding surface on one of the tarsal bones. The 
 other two are lateral, partly articular, and partly non-articular. The articular surfaces 
 are small, and often consist of more than one ; they join the contiguous metatarsal bones. 
 The tarsal extremity is wedge-shaped ; the upper or dorsal surface being very broad, 
 represents the base of the wedge ; the lower surface, being narrow, forms the point. 
 
 The anterior or digital extremity presents a head or condyle, flattened on the sides, and 
 oblong from above downward ; the articular surface extends much farther on the lower 
 aspect, or in the direction of flexion, than on the upper, or the direction of extension. 
 On the inside and outside of the condyle there is a depression, and a projection behind 
 it for the lateral ligament of the joint. 
 
 Characters of the different Metatarsal Bones. 
 
 The first or metatarsal bone of the great toe (m', figs. 54, 55, 56) is remarkable for its 
 great size. It is the only one which, in this respect, resembles the tarsus ; its body is 
 shaped like a triangular prism ; its digital extremity is marked on the plantar aspect by 
 a double furrow for two sesamoid bones (*, fig. 56). (Vide Articulation of the Foot.) Its 
 tarsaL extremity presents a semilunar concave surface, with its greatest diameter verti- 
 cal, which articulates with the internal cuneiform bone. There is no articular surface 
 on the circumference of the first metatarsal bone. In this point it resembles the first 
 metacarpal bone, and by this and its great size it is distinguished from all the others. 
 
 The fifth metatarsal bone (m, fig. 54, 55) is the shortest after the first ; it has only one 
 lateral articular face on its tarsal extremity. On the opposite side of this extremity, 
 viz., on the outside, we observe a large process, process of the fifth inetatarsal bone, shaped 
 like a triangular pyramid, and directed obliquely backward and outward, into which the 
 peroneus brevis is inserted. This process may be easily felt under the skin, and serves 
 as a guide in the partial amputation of the foot at the tarso-metatarsal articulation. 
 Another charact^iristic of the fifth metatarsal bone is the great obliquity outward and 
 backward of the %rticular face on its posterior extremity. 
 
104 OSTEOLOGY. 
 
 The second, third, and fourth metatarsal bones are distinguished from each other by 
 the following characters. 
 
 The second is the longest, and also the largest after the first ; it articulates with the 
 three cuneiform bones by its posterior extremity, which is dovetailed with them. The 
 third and the fourth metatarsal bones are of almost equal length ; their apparent difference 
 in an articulated foot depends chiefly on the fact that the articulation of the fourth with 
 the cuboid is on a plane posterior to that of the third with the external cuneiform bone. 
 Lastly, they may be known from each other by the presence of two surfaces, on the in- 
 side of the posterior extremity of the fourth metatarsal ; one being for the external cu- 
 neiform bone, and the other for the third metatarsal bone. 
 
 Development. — The metatarsal bones are developed from two points ; one for the body, 
 and one for the anterior or digital extremity. The first metatarsal bone is the only ex- 
 ception to this rule, for its epiphysary point is situated at the posterior extremity.* The 
 osseous point of the body appears first during the third month, according to the majority 
 of authors, but about the forty-fifth day, according to the observations of Blumenbach and 
 Beclard. It is completely developed in the foetus at the full period. The epiphysary 
 point makes its appearance during the second year. The union of these parts does not 
 take place until the eighteenth or nineteenth year, and is not simultaneous in all the 
 bones of the metatarsus. The epiphysis of the first metatarsal bone is the first to unite 
 with the body. An interval of a year sometimes intervenes between the union of this 
 epiphysis and those of the other four metatarsal bones. 
 
 The Toes [n o r, n r, Jigs. 54, 55). 
 
 The resemblance between the phalanges of the fingers and those of the toes is so com- 
 plete, that we cannot do better than refer to the description already given of the former 
 for details respecting the latter. At the same time, it should be remarked, that the pha- 
 langes of the toes appear, as it were, atrophied, or stinted in growth, when compared 
 with those of the fingers, excepting the great toe, which, in all its parts, preserves the 
 large dimensions of the inner side of the foot. 
 
 The first or metatarsal phalanx {n to n') resembles closely the metacarpal phalanx of 
 the fingers. The middle phalanx (o) is remarkably small and short ; it would almost ap- 
 pear to consist of the extremities alone, the body being absent. At first sight it might 
 be t£iken for a pisiform bone, or, rather, for one of the pieces of the coccyx ; but the 
 presence of anterior and posterior articular faces is sufficient to mark the distinction. 
 
 The ungual phalanges (r r') of the toes resemble in form, but are much smaller than 
 the corresponding parts of the fingers. This remark, however, only applies to the last 
 four, for the ungual phalanx of the great toe is in size at least double that of the thumb. 
 I cannot conclude this description without remarking, that the articular surface of the 
 posterior extremity of the metatarsal phalanges, as well as of the anterior extremity of 
 the metatarsal bones, is prolonged farther upward than the corresponding surfaces on 
 the metacarpal bones and phalanges of the fingers ; this arrangement allows a greater 
 extension of the toes, and is an important element in the mechanism of progression. 
 
 Development. — The first, second, and third phalanges are developed from two points 
 of ossification ; one for the body, and one for the metatarsal extremity. The epiphysary 
 points of the second and third phalanges are so small, that their existence has been 
 doubted by many anatomists. The osseous points of the bodies of the first phalanges 
 are much later in appearing than those of the metatarsal bones, not being visible, in 
 general, until from the second to the fourth month ; the first phalanx of the great toe is 
 an exception, its ossification concmiencihg from the fiftieth to the sixtieth day. The 
 epiphysary point of the first phalanges does not appear until the fourth year. The bodies 
 of the second phalanges are ossified almost at the same time as those of the first ; the 
 epiphysary point of their posterior extremity is not visible until from the sixth to the sev- 
 enth year. The bodies of the third phalanges are ossified before those of the second and 
 the first ; an osseous point appears in them about the forty-fifth day, excepting in the lit- 
 tle toe, where it is much later. The ungual phalanx of the great toe is remarkable as be- 
 ing ossified before all the other phalanges of the toes. It is developed from a point which 
 does not occupy the centre, but the summit of the phalanx. The epiphysary point of the 
 posterior extremity appears about the fifth year in the great toe, and about the sixth year 
 in the othei four. The epiphysary points of the phalanges are not united to the bodies 
 until the age of seventeen or eighteen years. 
 
 General Development of the Inferior Extremity. 
 The most characteristic feature of the lower extremity in the foetus is the comparative 
 Sateness of its development, which is most remarkable at the early periods. We have 
 
 * This exception corresponds entirely with that observed in the hand, and renders the analogy between the 
 metatarsal bone of the great toe and the metacarpal of the thumb extremely close ; for the same reason, both 
 of these bones resemble tke first phalanges of the fingers. I may add, that, in some subjects, it has appeared 
 to me that there was a very thin epiphysary point at the digital extremity of this bone, which soon united tn 
 the body 
 
COMPARISON Oi' THE EXTREMITIES. 106 
 
 already stated the periods at which each point of ossification appears in the diiferent 
 bones, and the times at which they are united, and it now only remains for us to point 
 out some peculiarities of development which have not been included in the description 
 of the bones. 
 
 From the observations of Bichat, it is generally admitted that the neck of the femur 
 in the foetus and the newly-born infant is proportionally shorter than in the adult, and 
 forms ahnost a right angle with the shaft of the bone ; that the body of the femur is al- 
 most straight ; and that its extremities are proportionally much larger than they become 
 subsequently. As we before observed with regard to the upper extremities, all these 
 assertions are at variance with the results of our observations. The same reflections 
 apply equally to the bones of the leg, the torsion of which we believe to exist to the same 
 degree in the foetus and in the new-bom infant as in the adult. 
 
 After birth, the development of the lower limbs proceeds more rapidly than that of the 
 upper, and the final proportions are not attained until the age of puberty. In the aged, 
 the phalanges of the toes are often anchylosed ; but this union, like the dislocations of 
 the toes, and some deformities of the tarsus and metatarsus, are the results of pressure 
 upon the foot occasioned by tight shoes, and the more or less complete immobility in 
 which the parts are maintained.* 
 
 Comparison of the Superior and Inferior Extremities. 
 
 We have hitherto omitted the applications of that species of comparative anatomy by 
 which different organs of the same animal are compared with one another. Those anal- 
 ogies which exist between the various parts that compose the trunk could not, with pro- 
 priety, be included in a work on descriptive anatomy. But we do not deem it proper to 
 apply the same rule to the parallel between the upper and lower extremities ; for that is 
 founded on such numerous and striking points of analogy, and has become so much a 
 subject of instruction, that we should consider it a serious omission did we here neglect 
 giving a brief notice of it. 
 
 The upper and the lower extremities are evidently constructed after the same type, 
 but present certain modifications corresponding to the difference of their functions. I 
 should remark in this place, that some of these analogies are very manifest and satis- 
 factory, and greatly facilitate the remembrance of important anatomical details ; while 
 others are far-fetched, and wholly destitute of useful application : these will be passed 
 over with a simple notice. We shall now compare in succession the shoulder and the 
 haunch, the humerus and the femur, the forearm and the leg, the hand and the foot. 
 
 Comparison of the Shoulder and the Pelvis. 
 Before the time of Vicq-d'Azyr, anatomists were in the habit of considermg the clavi- 
 cle and the scapula among the bones of the upper extremity, but regarded the os innom- 
 inatum or haunch as belonging to the trunk ; and yet the most simple reflection is suf- 
 ficient to establish the analogy between the shoulder and the haunch. In order the 
 more readily to appreciate the points of resemblance and difference between these parts, 
 it is advisable to follow the method adopted by Vicq-d'Azyr, of studying the shoulder 
 reversed ; or, what is the same thing, to compare the aspect of the shoulder which cor- 
 responds to the head, with that of the pelvis which answers to the coccyx ; remember- 
 ing, at the same time, that, for a long period after birth, the haimch bone is formed of 
 three distinct pieces, the ilium, the ischium, and the pubes. 
 
 1. The shoulders form an osseous girdle, intended to form a point of support for the 
 upper extremities, in the same manner as the haunch does for the lower extremities. 
 The girdle formed by the shoulders is interrupted in front in the situation of the sternum, 
 and behind, opposite the vertebral column ; hence there are two shoulders, while the 
 haunch bones constitute one united whole. The shoulder, therefore, and, consequently, 
 the arm of one side, are completely independent of those of the other, but the two lower 
 extremities have a sohd bond of union. 
 
 2. The second point of difference relates to the comparative dimensions of the pelvis 
 and the shoulder. The great size of the pelvis, the thickness of its edges, the depth of 
 its notches, and the prominence of its eminences, contrast strongly with the slender 
 construction of the shoulder, and the thin edges of the scapula, and are in harmony with 
 the uses of the lower extremities. 
 
 3. The broad portion of the scapula is analogous to the iliac portion of the os innom- 
 inatum ; the internal iliac fossa is analogous to the subscapular fossa. 
 
 4. The supra and infra-spinous fossae correspond to the external iliac fossa ; but the 
 iliimi has no part analogous to the spine of the scapula. 
 
 5. The axillary border of the scapula answers to the anterior edge of the os innomi- 
 natum. The spinal border is analogous to the crest of the ilium. The superior border 
 
 * On thi» subject the reader may consult a very curious memoir, by Camper, on the inconveniences arising 
 from tight shoes, to which he attributes, 1. The shortening of the second toe ; 2. The partial luxation of some 
 of the tarsal bones. To this vie may add the luxation, outward, of the first phalanx of the great toe ; and the 
 luxation, inward, of the first phalanx of the second, and sometimes of the third toe. 
 
 o 
 
106 OSTEOLOGY. 
 
 of the scapula corresponds to the posterior border of the os innominatuin ; and the cora^ 
 coid notch on this border, with the coracoid hgament which converts it into a foramen, 
 are analogous to the sciatic notch, and the sacro-sciatic ligaments. 
 
 6. The glenoid cavity is evidently analogous to the acetabulum ; according to Vicq- 
 d'Azyr, the coracoid and the acromion processes are represented by the tuberosity of 
 the ischium and the pubes, with this remarkable difference only, that the two processes 
 of the shoulder are separated from each other by the large acromio-coracoid notch, while 
 in the pelvis the iscliium and the pubes are united, and, instead of including a notch, 
 form the circumference of a foramen, the obturator. This analogy is not universally 
 admitted ; for the ischium, being intended to sustain the weight of the body when sit- 
 ting, bears no resemblance in this respect to the shoulder. One of the most striking 
 analogies between the shoulder and the pelvis is that of the clavicle and the horizontiS 
 portion of the pubes ; with this difference, that the clavicle is articulated with the scap- 
 ula, while the pubes is united by bone to the ilium. Without forcing an analogy, we 
 may trace a similitude between the symphysis pubis, and the union of the clavicles by 
 means of the interclavicular ligament. 
 
 Comparison of the Arm Bone and the Thigh. 
 
 In order to make the parallel exact, we must remember the relative situation of the&o 
 two bones, and compare the right femur with the left humerus ; and the side of flexion, 
 that is, the posterior aspect of the first, with the side of flexion, or the anterior aspect of 
 the second. This being determined, we must place the linea aspera of the femur in front, 
 and the himierus in its natural position. The humerus is much smaller than the femur, 
 being about a third shorter, and only half the weight and bulk. The humerus is placed 
 vertically, and almost parallel to the axis of the trunk ; in this it contrasts with the 
 marked obliquity of the thigh bones, which touch each other at their lower ends. The 
 humeri are separated from each other by a greater distance than the femora ; this differ- 
 ence depends on the conformation of the human thorax, which is flattened in front and 
 behind, while in quadrupeds it is flattened on the sides, and permits the approximation 
 of the humeri, which serve as pillars of support to the fore part of the trunk. 
 
 The humerus is not curved like the femur, but, on the other hand, it is much more 
 twisted, and presents an oblique groove, which does not exist in the femur. We shall 
 compare in succession the shafts and the extremities of these bones. 
 
 1. Comparison of the Shafts. — -The posterior surface of the humerus exactly corresponds 
 to the anterior surface of the femur, being, like it, smooth and rounded. The external 
 surface resembles the external plane of the femur, with some differences ; the impres- 
 sion for the gluteus maximus is evidently analogous to the deltoid impression. The in- 
 ternal surface is in contact with the brachial artery, as is the internal surface of the 
 femur with the femoral artery. The anterior edge is a sort of linea aspera, analogous 
 to that of the femur, and, like it, terminating by a bifurcation at its upper part. 
 
 2. Comparison of the Loicer Ends of the Bones. — Although the differences between 
 these parts are very marked, we can yet detect, in the one bone, traces of all the more 
 important points of structure observed in the other. Thus, the internal and external 
 tuberosities of the humerus evidently resemble those of the femur, and they are both 
 intended for the insertion of muscles and ligaments. The trochlea of the humerus re- 
 sembles that of the femur, with this difference, that, in the femur, the two borders of 
 the pulley diverge from each other behind, while in the humerus they are parallel through- 
 out. In front and behind the femoral trochlea, we find depressions, wliich are manifestly 
 analogous to the coronoid and olecranal fossae of the humeral trochlea. Lastly, without 
 admitting any fundamental difference, we may explain the existence of the small head 
 of the humerus, for which there is no representative in the femur, by a reference to the 
 fact, that both bones of the forearm unite with the humerus, while only one bone of the 
 leg articulates with the femur. 
 
 Comparison of the Upper Ends. — As in the femur, we find in the humerus a segment 
 of a spheroid, or a head, supported by a neck, of which, however, there is only a trace ; 
 and two tuberosities, which are analogous to the trochanters, and, like them, give at- 
 tachment to the rotator muscles of the Umb. In the humerus, however, the two pro- 
 cesses are much more closely approximated, being only separated by the bicipital groove. 
 Lastly, the great tuberosity of the humerus causes the prominence of the shoulder, in 
 the same manner as the great trochanter causes the prominence of the hip. 
 
 Comparison of the Leg and Forearm. 
 
 The forearm is that portion of the upper extremity which is represented by the leg in 
 the lower. Each is composed of two bones ; but while the leg is essentially constitu- 
 ted by the tibia, which alone enters into the formation of the knee-joint, and the greater 
 part of the ankle-joint, both the radius and the ulna contribute, almost in an equal degree, 
 to that of the forearm ; and although the ulna forms the greater part of the elbow-joint, 
 the radius, by a sort of compensation, is the chief bone of the wrist-joint. 
 
 Although the general analogy between the forearm and leg is sufficiently striking, it js 
 
COMPARISON OP THE EXTREMITIES. 107 
 
 not so easy to trace the corresponding parts in detail. Anatomists are much at variance 
 on this subject, particularly as to which bone of the forearm corresponds to the tibia. 
 
 Vicq-d'Azyr, from a consideration of the elbow and the knee joints, came to the con- 
 clusion that the ulna is analogous to the tibia, and the radius to the fibula. M. de Blain- 
 Tille, on the contrary, reflecting on the relations between the leg and foot, and the fore 
 arm and hand, and considering that the tibia is placed on the same line with the great toe, 
 and the radius with the thumb, and also that in the forearm the radius constitutes the 
 chief part of the wrist-joint, and that in the leg the tibia is most concerned in the ankle- 
 joint, is of opinion that the tibia and the radius are analogous parts. 
 
 We shall adopt what is true in either opinion, and reject what appears to us too un 
 conditionally stated or incorrect ; and, therefore, considering, 1. That neither of the bones 
 of the leg resembles, by itself, one of the bones of the foreann ; 2. That each bone of the 
 leg has some characters, both of the ulna and of the radius ; 3. That the natural position 
 of the forearm being that of pronation, and that the leg being in a state of constant pro- 
 nation, it is incorrect to compare the forearm when supinated with the leg when in the 
 opposite position ; 4. That comparative anatomy has shown, in ruminating animals, the 
 upper extremity of the ulna to be blended with the radius, and a slender process on the 
 external aspect of the forearm resembUng the fibula, we are inclined to believe that the 
 upper end of the tibia is represented by the upper lialf of the ulna, and the lower half of 
 the tibia by the lower half of the radius ; while the fibula is represented by the upper part 
 of the radius and the lower part of the ulna. If we enter into details, we shaU see how 
 plausible this comparison is in reality. 
 
 Comparison of the Upper Half of the Ulna and the Upper Half of the Tibia. 
 
 The horizontal portion of the great sigmoid cavity of the ulna is represented by the 
 upper end of the tibia, and the crest which separates the two surfaces of the cavity is 
 analogous to the spine of the tibia. The patella and the olecranon are constructed after 
 the same type ; the mobility of the first, and the fixture of the last, are not essential dif- 
 ferences. The body of the ulna is prismatic and triangular, like that of the tibia ; its in- 
 ternal surface is superficial and almost subcutaneous, like the anterior surface of the 
 tibia ; its posterior edge (crest of the ulna) is prominent, and represents the crest of the 
 tibia ; it is equally superficial, and serves as a guide in the diagnosis and coaptation of 
 fractures. As in the tibia, the crest of the ulna is continuous with a triangular tuberosity, 
 which may be called the posterior tuberosity of the ulna, and is analogous to the anterior 
 tuberosity of the tibia. 
 
 Comparison of the Lower Part of the Radius and the Lower Part of the Tibia. 
 
 The quadrangular lower end of the radius corresponds to the equally quadrangulai 
 lower extremity of the tibia. The inferior articular surface of both is divided into two 
 parts, by an antero-posterior ridge. The ulnar side of the lower end of the radius is 
 hollowed into an articular cavity, in the same way as the fibular side of the lower end 
 of the tibia. The styloid process of the radius answers to the internal malleolus of the 
 tibia. Both extremities exhibit furrows for the passage of tendons. 
 
 Comparison of the Hand and Foot. 
 The back of the foot corresponds with the back of the hand, the sole with the palm, the 
 tibial edge of the one with the radial edge of the other ; the fibular and the ulnar borders 
 are analogous ; the tarsal extremity of the foot corresponds with the carpal extremity of 
 the hand, and each has a digital extremity. But amid these features of resemblance, 
 which are sufficient to establish the old adage, pes altera manus, we find also great dif- 
 ferences. Thus the foot exceeds the hand both in size and weight, being longer and 
 thicker, though it is narrower : this excess of volume does not affect the toes, which are 
 mcomparably smaller than the fingers ; nor the metatarsus, but is confined to the tarsus, 
 of which the carpus seems little more than a vestige. A second characteristic differ- 
 ence is the absence of the power of opposition in the great toe. As far as regards func- 
 tion, indeed, it may be truly said, that the want of this power constitutes a foot, and the 
 Eossession of it a hand. A third difference results from the mode of articulation of the 
 jg with the foot, for the leg does not articulate with the posterior extremity of the tar- 
 sus, but Avith its upper surface, so that a part of the tarsus projects behind the joint, and 
 the axis of the foot forms a right angle with that of the leg. These remarks will suffice 
 to show the general differences between the hand and the foot. 
 
 Comparison of the Bones of the Carpus and Tarsus. 
 While the carpus scarcely forms the eighth part of the hand, the tarsus constitutes 
 half the foot. Its antero-posterior diameter, which is five or six inches, is three times 
 greater than the transverse diameter, precisely contrary to what is the case in the hand. 
 The tarsus resembles a vault, concave below, both in the antero-posterior and transverse 
 directions, and receives the leg upon its summit. The carpus is nothing more than a 
 groove for tendons. It is manifest that the carpus is only the rudiment of the tarsus, 
 which is not surprising, if we consider that the former is truly the fundamental part of 
 
lOS OSTEOLOGY. 
 
 the foot, and the basis of support to the whole body. We shall examine in detail the 
 analogies and the differences of these two constituent parts of the foot and the hand. 
 They differ in the following respects : 1. There are eight bones in the carpus : there are 
 only seven in the tarsus. 2. Each of the two rows of the carpus is composed of four 
 bones : the first row of the tarsus consists of two bones, and the second of five ; 3. The 
 bones of the first row of the tarsus are placed one above the other, not arranged side by 
 side as in the first row of the carpus. 4. One tarsal bone only enters into the formation 
 of the ankle-joint, while three of the carpal bones are concerned in the wrist-joint : last- 
 ly, the second row of the tarsus is subdivided into two secondary rows on the inside, a 
 posterior, formed by the scaphoid, and an interior, formed by the three cuneiform bones. 
 We shall now compare the bones of these two regions, and for the want of their re- 
 semblance in shape, we shall have recourse to that of their mode of connexion — a meth- 
 od which is, perhaps, more constant and important than that which is founded upon a 
 character so variable as figure. 
 
 Comparison of the Metatarsal Row of the Tarsus with the Metacarpal Row of the Carpus. 
 
 The metatarsal and the metacarpal rows are evidently more analogous to each other 
 than the first rows of each region, and have, therefore, been chosen for the purpose of 
 establishing the parallel. 
 
 1. The cuboid is manifestly analogous to the os unciforme ; their relative positions 
 are the same ; their forms are, in a great measure, similar ; and while the cuboid is at- 
 tached to the last two metatarsal bones, the os unciforme articulates with the last two 
 metacarpal. This analogy being admitted, we shall find in the three cuneiform bones 
 the representatives of the three other bones of the second row of the carpus, viz., the 
 trapezium, the trapezoid, and the os magnum. 
 
 2. We must admit here that the analogies now become much less evident. Never- 
 theless, the third cuneiform bone, which, from being in contact with the cuboid, should 
 represent the os magnum, which is contiguous to the os unciforme, does so far agree, 
 that it articulates with the third metatarsal bone, as the os magnum does with the third 
 metacarpal ; and, what is sufficiently remarkable, the third cuneiform has a slight con- 
 nexion with the second metatarsal, as the os magnum has with the second metacarpal. 
 Although, therefore, we do not find in the third cuneiform bone anything approaching 
 to the size of the os magnum, or resembling the remarkable head of that bone, we should 
 not, on that account, hastily conclude that they have no analogy. We shall explain af- 
 terward how this fact should be interpreted : we only wish it to be admitted in this 
 place, that the base or metacarpal portion of the os magnum is represented by the third 
 cuneiform bone. 
 
 3. The second cuneiform bone, which corresponds to the trapezoid, supports the sec- 
 ond metatarsal, as the trapezoid supports the second metacarpal. 
 
 4. The first cuneiform bone, which supports the first metatarsal, corresponds to the 
 trapezium, which supports the first bone of the metacarpus. All these analogies, it must 
 be confessed, are very imperfect, and founded rather upon the connexions than the forms 
 of the different bones. In fact, what resemblance is there between the three large cu- 
 neiform bones all cut into facette-like wedges, and all so like each other in shape, and 
 the bones of the carpus, to which we have compared them 1 Above all, what compari- 
 son can be established between the third cuneiform, which exactly resembles a wedge, 
 and the os magnum, which has a rounded head 1 There is nothing in the metatarsal 
 range of the tarsus which represents the rounded head which belongs to the metacarpal 
 row of the carpus ; but the following considerations, which did not escape the notice of 
 Vicq-d'Azyr, will serve to solve the difficulty. 
 
 1. It is an observation which apphes with sufficient generality to the whole skeleton, 
 that when two bones move upon each other, one being provided with a head, and the 
 other with a cavity, the head moves upon the cavity, not the cavity on the head. Thus, 
 the femur moves upon the os innominatum ; the humerus upon the scapula. 2. The hand, 
 in the performance of its functions, almost always moves upon the forearm. In the move- 
 ments of the hand, the metacarpal row of the carpus moves upon the first row, and 
 therefore the metacarpal row presents the head. On the contrary, in the movements of 
 the bones of the tarsus during progression, the bones of the first row always move upon 
 those of the second or metatarsal row ; and consequently, instead of finding a rounded 
 head in the second row, we meet with it in the first. 
 
 Proceeding thus by the method of exclusion, it now only remains for us to establish 
 the analogy between the bones of the first row of the carpus on the one hand, and the 
 scaphoid, the os calcis, and astragalus on the other. The analogies here are very equiv 
 ocal, and are not agreed upon among anatomists. 
 
 Comparison of the First Row of the Tarsus with the First Rmo of the Carpus. 
 
 As there are only three bones in the posterior row of Uie tarsus which correspond to 
 the antibrachial or superior row of the carpus, it might be supposed, d priori, that one of 
 these would correspond to two of the bones of the first row of the carpus. A verv slight 
 
COMPARISON OP THE EXTREMITIES. 109 
 
 examination of the tarsus and the carpus in a quadruped will show at once that the 
 pisiform bone is represented by that part of the os calcis which projects behind the as- 
 tragalus. The OS calcis is the only bone of the tarsus which is developed from two 
 points ; and this establishes a strong presumption in favour of the opinion that it repre- 
 sents two bones. If we admit the analogy of the back part of the os calcis with the pi- 
 siform bone, the anterior portion of this bone would represent the cuneiform or pyram- 
 idal bone of the carpus ; and as this last articulates with the os unciforme, so the an- 
 terior portion of the os calcis unites with its representative, the cuboid. The os calcis, 
 then, may be considered as representing the cuneiform and the pisiform bones blended 
 together, and much augmented in size. 
 
 It remains, then, to establish the analogy between the scaphoid and semilunar bones of 
 the hand, and the astragalus and scaphoid of the foot. 
 
 The scaphoid of the hand resembles the scaphoid of the foot, both in form and con- 
 nexions. The similarity of shape has led to the identity of name ; and, with regard to 
 connexions, we find that the scaphoid of the foot is attached to the three cuneiform 
 bones, and that of the hand to the trapezium, the trapezoid, and the os magnum, which 
 represent the three cuneiform bones ; and, lastly, we observe that the scaphoid bone of 
 the foot is placed on the same side as the great toe, and that the scaphoid bone of the 
 hand is placed on the same side as the thumb. There is, however, one remarkable dif- 
 ference between them, viz., that the scaphoid bone of the hand articulates with the fore- 
 arm, while that of the foot has no connexion with the leg. 
 
 "We have now only to discover in the tarsus the representative of the semilunar bone. 
 All the rest of the bones being now excluded, we can only conclude, with Vicq-d'Azyr, 
 that the astragalus is its counterpart, with the mere addition of a rounded head. 
 
 Comparison of the Metacarpus and the Metatarsus. 
 
 Five small long bones, arranged parallel to eacli other, form both the metacarpus and 
 the metatarsus. In both there are four interosseous spaces : these are larger in the 
 hand than in the foot, because there is a greater disproportion between tlie bulk of the 
 extremities and shafts of the metacarpal than of the metatarsal bones : the metacarpus, 
 from being shorter, appears broader than the metatarsus. The most distinguishing char- 
 acter of the metacarpus is the fact, that the metacarpal bone of the thumb is the short- 
 est of the whole, and is situated on a plane anterior to the others, and that its direction 
 is oblique, aU which circumstances bear reference to the movement of opposition, which 
 is peculiar to the hand. The characteristic mark of the inetatarsus is the size of the 
 first metatarsal bone, which greatly exceeds that of all the others. The great size of 
 the tarsus is continued in this bone and the great toe, on account of the important part 
 they perform in the mechanism of standing. There is so great a resemblance between 
 the other metacarpal and metatarsal bones, that some attention is necessary in order to 
 distinguish between them. 1. The metatarsal bones gradually diminish in size from 
 their tarsal to their digited extremities ; the metacarpal bones, on the contrary, are most 
 expanded at their digital ends. The metacarpal are shorter and thicker ; the metatar- 
 sal longer and more slender. The shaft of the metacarpal bones is pretty regularly pris- 
 matic and triangular ; that of the metatarsal, on the contrary, is compressed or flatten- 
 ed on the sides. 2. There are no well-marked differences between the carpal extremi- 
 ties of the metacarpal bones and the tarsal extremities of the metatarsal ; but the lat- 
 ter are larger than the former, which agrees with the greater dimensions of the tarsus. 
 3. The tarsal extremities are more regularly cuneiform than the corresponding ends of 
 the metacarpal bones. 
 
 The most characteristic differences, however, of these two series of bones are found 
 in the digital extremities, which are incomparably larger in the metacarpus than in the 
 metatarsus, the fingers being the chief part of the hand, while the tarsus is the principal 
 portion of the foot. We should also remark, that the convex articular surfaces of the 
 digital ends of the metatarsal bones are prolonged farther on the dorsal aspect than the 
 corresponding surfaces of the metacarpal bones. 
 
 Comparison of the Phalanges of the Fingers and Toes. 
 
 The fingers, being the essential organs of prehension and the fundamental part of the 
 hand, greatly exceed the toes both in length and thickness, and the latter may be looked 
 upon as representing in rudhnent the former, being precisely analogous in structure. 
 
 The phalanges of the toes may, therefore, be regarded as phalanges of the fingers in 
 a state of atrophy ; but the great toe forms a remarkable exception to this rule, for its 
 phalanges are much larger in proportion to the other toes than the phalanges of the 
 thumb are to the other fingers. This magnitude of the great toe corresponds to the size 
 of its metatarsal bone, and accords with its destination, as constituting the principal sup- 
 ■^rt for the weight of the body in front. The first phalanx of the toes exactly resembles 
 the first phalanx of the fingers in all things but volume. The middle phalanx of the toes 
 can scarcely be recognised, from its diminutive size : it may be said to want the shaft al- 
 together, the extremities being in contact. As we have already^remarked, it might at 
 
110 OSTEOLOGY. 
 
 first sight be confounded with a pisiform, or a sesamoid bone, or still more readily with 
 a piece of the coccyx. 
 
 Comparison of the Upper and Lower Extremities with regard to Development. 
 
 The development of the lower extremities is proportionally less rapid than that of the 
 upper. The clavicle and the scapula are ossified before the os innominatum. The os- 
 sification of the skeleton commences in the clavicle ; in this bone, the osseous nodule is 
 visible from the twenty-fifth to the thirtieth day ; it appears in the scapula about the for- 
 tieth day. The osseous point of the ilium is visible about the forty-fifth day, that of the 
 ischium in the third month, and that of the pubes in the fifth month. The scapula is 
 completely ossified at the age of twenty years ; the marginal process of the crest of the 
 ilium is scarcely united until the twenty-fifth year. The bony centres of the shafts of 
 the femur and humerus are almost simultaneous in their appearance. The germ of the 
 lower end of the femur always exists at birth ; that of the lower end of the humerus does 
 not appear until the end of the first year ; but this latter unites with the bone at eighteen 
 years, while the former is still separate at twenty years. The tibia is ossified a little be- 
 fore the bones of the forearm, the fibula a little after them. The ossification of the leg 
 and the forearm is completed almost about the same time. The ossification of the bones 
 of the tarsus precedes that of the carpus by a considerable period. Thus, at from foui 
 and a half to five months of foetal life, a bony point is visible in the os calcis, and some 
 days after in the astragalus ; the os magnum and os cuneiforme (which, however, ar« 
 not the representatives of the preceding) do not show ossific points until a year after 
 birth. The pisiform bone is not ossified until the twelfth year ; while the latest of the 
 tarsal bones, the scaphoid, is converted into bone at the fifth year. Nevertheless, the 
 epiphysary point of the os calcis (which we have shown to be analogous to the pisiform 
 bone) does not become visible until the tenth year ; this fact strengthens the analogy 
 between the pisiform bone and the epiphysary lamina of the os calcis. 
 
 The metatarsal bones are developed in exactly the same manner as the metacarpal, 
 only at a somewhat later period. The union of the epiphyses takes place a little earlier 
 in the metatarsus than in the metacarpus. The toes are ossified at a later period than 
 the fingers ; especicdly the ungual and the second phalanges, which are much later than 
 those of the fingers. 
 
 It is, no doubt, impossible to state the precise reason for these differences ; but it is 
 sufficient to find a positive relation between the rate of development of these parts, and 
 the offices they are intended to fulfil. 
 
 The Os Hyoides, or the Hyoid Apparatus* (fig. 57). 
 
 The OS hyoides has a parabolic form, resembling the upsilon of the Greeks, whence its 
 name. It is the only bone which is detached from the rest or 
 Fig. 57. ^ the skeleton ; it is connected only by ligaments and muscles, and 
 
 is situated between the base of the tongue and the larynx. It is 
 larger in the male than in the female. It is placed almost hori- 
 zontally, the concavity of its curve looking backward, and the 
 convexity forward. 
 
 This bone is divided into five parts ; viz., a body or middle 
 part (a), ani four cornua, two large (J) and two small (c). This 
 multiplicity of parts, which is much greater in some animals, es- 
 pecially fishes, justifies the name of " hyoid apparatus," which 
 we have adopted.! 
 
 The body of the os hyoides (a) is quadrilateral, elongated, and curved, with the cavity 
 behind. Its anterior surface looks upward, and presents a crucial projection, the vestige 
 of a process which in many animals is prolonged into the substance of the tongue. This 
 projection gives attachment to several muscles, the insertions of which are marked by 
 transverse lines, interrupted by tubercles. The posterior surface, more or less excavated 
 in different individucds, is sometimes connected with a yellow ceUular tissue, which sep- 
 arates it from the epiglottis, and is sometimes covered by a synovial membrane. Its ex- 
 cavation, which is never very great in man, is the vestige of the enormous cavity which 
 exists in the hyoid of the Howler monkey. The lower edge gives attachment to the thy- 
 ro-hyoid muscle only. The upper edge gives insertion to a yeUow membrane, a sort ol 
 ligament which stretches into the tongue ; and also to the yeUow thyro-hyoid ligament, 
 which has been incorrectly stated to be inserted into the lower edge of the bone. The 
 extremities of the body of the os hyoides are covered by cartilage for articulation with 
 the great cornua. 
 
 The great cornua or rami {b) are much longer than the body, and flattened above and 
 below, while the body is compressed from before backward. They are expanded at the 
 place where they articulate with the body, pass backward, and, after being contracted 
 
 * I have introduced the description of the os hyoides into this place, because, although chiefly belonging to 
 the tongue, it gives attachment to several muscles, and, therefore, should be previously knovfn to the student 
 t Vide M QeofFroy Saint-Hilaire, on the anterior bones of the chest. — {Philos. Anat., vol. i., p. 139.) 
 
THE ARTICULAR CARTILAGES. HI 
 
 and flattened, terminate in a rounded tubercle, which is sometimes surmounted by an 
 epiphysis. ♦ 
 
 The little comua (c) are called also styloid cornua, because they are connected with the 
 styloid process by means of a ligament. They are two pisiform nodules at the point of 
 junction of the great comua with the body of the hyoid {ossa pisiformia lingualia of 
 Soemmering). They surmount the upper edge of the bone, and are directed upward and 
 outward ; their length is very variable. In the lower animals, the prolongations which 
 correspond to these httle cornua are much longer than the great cornua in man. They 
 articulate by their lower end with the body and the great cornua. Their upper part gives 
 attachment to a ligament, which unites it with the styloid process. This ligament 
 which is sometimes ossified in man, is always a bony connexion in the lower animals.* 
 
 Internal Structure. — The hyoid bone is composed chiefly of compact tissue ; but there 
 is a small quantity of spongy tissue in the thick parts of the body and the great cornua. 
 
 Development. — The os hyoides is developed from five points ; one for the body, two for 
 the great comua, and two for the little cornua.. Some anatomists admit two points for 
 the body, and make the whole number six. 
 
 The ossification of the great cornua precedes that of the body, which becomes bony 
 soon afl;er birth ; the little cornua are not ossified until some months afl;er. All the pie- 
 ces are at first separated by considerable portions of cartilage, afterward by a very thin 
 layer, which sometimes remains during life, and gives the different parts of the bone a 
 great degree of mobility. 
 
 THE ARTICULATIONS, OR ARTHROLOGY. 
 
 General Observations. — Articular Cartilages. — Ligaments. — Synovial Membranes. — Classi- 
 fication of the Joints. — Diarthroses. — Synarthroses. — Amphiarthroses, or Symphyses. 
 
 The bones are united together by the joiTits or articulations. The study of these parts 
 is the object of syndesmology, or, more properly, of arthrology {apdpov, a joint). In exam- 
 ining each joint, it is necessary to consider, 1. The contiguous surfaces of the bones, or 
 the articular surfaces ; 2. The uniting medium, or the ligaments ; 3. The means or condi- 
 tions which facilitate the motion of the parts, the syiwvial membranes ; and, 4. The move- 
 ments of which the joint is capable, t 
 
 It is impossible to insist too much upon the importance of a careful study of the artic- 
 ulations. There is no part of anatomy a thorough knowledge of which is more indis- 
 pensable both to the physiologist and the surgeon ; without it the former cannot form a 
 correct idea of the animal mechanism, nor can the latter appreciate the nature of those 
 numerous injuries and diseases of which the articulations are the seat. 
 
 Before describing the forms and the motions of the different joints, it is necessary to 
 give a general idea of the articular cartilages, the synovial membranes, the hgaments, 
 &c. ; in short, of all the means which contribute to secure the solidity and mobility of 
 the articulations. 
 
 The Articular Cartilages. 
 
 It has been observed,t that when two osseous surfaces in immediate contact rub upon 
 each other, they are gradually absorbed in such a manner as to render the movements 
 between them diflicult and painful. In order to avoid these injurious effects in the joints, 
 the contiguous surfaces of the bones are covered by a layer of cartilage (the incrusting 
 or articular cartilage), a substance which unites in itself the qualities of solidity, pliability, 
 and elasticity in a high degree, yielding when compressed, and returning to its former 
 state when the pressure is removed. These articular cartilages exist in all the mova- 
 ble joints. The extent of surface which they cover is generally proportioned to the ex- 
 tent of motion in the joints. Their thickness is generally greatest when the bones 
 which they cover are most movable,' and most subjected to pressure. An articular car- 
 tilage is not of uniform thickness throughout. Thus, on convex surfaces, the cartilagi- 
 nous layer is thicker in the centre than at the circumference ; and, on the other hand, the 
 cartilages of articular cavities are thickest at the circumference. The most perfect co- 
 aptation results from this arrangement. It should also be remarked, that the most vio- 
 lent shocks are applied to the centre of the heads of the bones, and to the circumference 
 of the cavities. 
 
 The articular cartilages present, 1. A free surface, perfectly smooth and polished, which 
 is in the interior of the articulation ; 2. An adherent surface, which is so closely attached 
 
 * In the lower animals, the styloid process is detached from the cranium, and forms one of the hyoid chain 
 of bones, which is composed, 1. Of the five pieces of the os hyoides ; 2. Of the bones which supply the place 
 of the styloid ligaments ; 3. Of the styloid processes, or, rather, bones : nine pieces in all. 
 
 t Three of these, viz., the configuration of the articular surfaces, the ligaments, and the niovements of the 
 joint, are essentially related to each other; so that we may deduce, <i priori, the means of union, and the 
 movements of any joint, from the shape of the articular surfaces, and vice verscL. 
 
 % Absorption of the cartilages is a frequent disease of the joints, and obliges the individuals affected by h 
 to maintain constant rest 
 
112 ARTHROLOOy. 
 
 to the tissue of the bone, that it is impossible to separate it excepting in cases of disease. 
 In some cases of white swelling, I have been able to remove the articular cartilages with 
 great facility, and in these it appeared that the adherent surface of the cartilage was 
 very irregular, and that the fibres of the bone were implanted in it by innumerable small 
 prolongations. 
 
 Tliere is another kind of cartilage existing in certain joints, in the form of thin plates, 
 having both surfaces free, and being interposed between two articulating bones. These 
 are generally found in such joints as are exposed to the most violent shocks, and sub- 
 jected to the most frequent movements ; they are known by the name of inter-articular 
 cartilages. Their use is to adjust the contact of the surfaces on the bones, to moderate 
 the intensity of the shocks to which they may be submitted, to increase in some cases 
 the depth of the articular cavities, and to impart solidity to the joints. They are almost 
 always bi-concave, from which circumstance the name of meniscus is sometimes applied 
 to them (from iirjvrj, lund) ; they are thick at the circimiference, and very thin in the cen- 
 tre, which is sometimes perforated. 
 
 These two kinds of cartilage are found only in those joints the surfaces of which are 
 simply in contact. 
 
 The articulations of continuous surfaces are provided with cartilages very different 
 from the above, and which should be looked upon as non-ossified portions of the original 
 cartilage of ossification. The progress of ossification always encroaches upon them, 
 while the regular articular cartilages are never affected in this way. It will be seer 
 afterward that the articular cartilages are inorganic, like the enamel of the teeth, anc 
 the horny tissues, which are worn away by attrition, and are not susceptible of any le 
 sions, excepting such as arise from mechanical injury or chemical action.* 
 
 The Articular Ligaments.^ 
 
 The ligaments constitute a very important division of the fibrous tissue, which is met 
 with in all parts where great resistance and great flexibility are required, and in no part 
 of the body are these requisites more necessary than in the joints. They consist of 
 bundles of flexible and inextensible fibres of a pearly- white lustre, sometimes parallel 
 and sometimes interlaced. Sometimes tliey are placed between the osseous surfaces^ 
 and are then named interosseous ; sometimes, on the contrary, they occupy the circum- 
 ference of the surfaces, and are then called peripheral or capsular. The peripheral liga- 
 ments present two surfaces : a deep surface, lined by the synovial membrane, which is 
 intimately united to it, and which is so delicate that were it not from its development in 
 disease, its existence here might be doubted ; and a superficial, which is in contact with 
 the muscles, tendons, nerves, vessels, and cellular tissue, in a word, to all the structures 
 which surround the articulations ; and also tico extremities, which are attached to the 
 bones, at a greater or less distance from the cartilage. The adhesion of these parts is 
 so intimate, that it is easier to break either the ligament or the bone than to separate 
 them at the precise place of their union. 
 
 The ligaments may be classed under two very distinct heads : 1. The fasciculated, or 
 those which exist in bundles ; and, 2. The membranous or capsular. The ligaments, 
 properly so called, belong to the first class ; the fibrous capsules belong to the second. 
 We may admit a third form, which consists of scattered fibres, too far separated to 
 form fasciculated ligaments, and too few in number to constitute articular capsules. We 
 should include, also, in the class of articular ligaments, two very remarkable modifica- 
 tions of the fibrous tissue: 1. The articular borders; these are circlets of fibres which 
 sunnountthe margins of articular cavities, belonging to that class of joints denominated 
 enarthroses ; they augment the depth of the cavities, and act as a kind of pad to break 
 the force of impulsion of the articular head against the brim of the cavity, and prevent 
 this edge from breaking. 2. The yellow or elastic ligaments, which are characterized by 
 their yellow colour, extensibility, and elasticity ; hence the name of yellow elastic tissue 
 has been given to them, on account of their colour and chief property. 
 
 The Synovial Membranes^ or Capsules. 
 In every part of the body where fibres move, they are surrounded by cellular tissue, 
 which secretes a lubricating fluid to facilitate their motions ; and, where surfaces move 
 upon each other, they are covered by a membrane which exudes a fluid, varying in its 
 nature according as the motions are confined to simple gliding, or are accompanied by a 
 certain amount of friction. In the first case, the membranes secrete a watery or serous 
 fluid, and are, consequently, denominated serous membranes ; in the second, the liquid is 
 of an unctuous nature, resembling white of egg ; it is called synovia (avv, with, and u6v, 
 an egg), and the membrane synovial membrane. All the movable articulations are pra 
 
 * [Though the articular cartilages may be non-vascular, it is scarcely correct to say that they are unor- 
 ganized.] 
 
 t The word ligament, ovvlea/ios of the Greeks, copula or vinculum of the Latins, is applied, in anatomy, to 
 any structure which serves to unite different parts to each other. In this sense we speak of the broad and the 
 round ligaments of the uterus, the ligaments of the bladder and of the liver. Taken in its most limited aeamtt 
 this name applies exclusively to the articular ligaments. 
 
CLASSIFICATION OF THE JOINTS. 113 
 
 Tided with a synovial membrane or capsule, by means of which the parts are constantly 
 lubricated with a viscid, unctuous fluid, that favours the exact adaptation of the articular 
 surfaces, obviates the effects of friction, and maintains them in contact. This is the 
 cause of the noise or cracking which results from the sudden separation of the articulai 
 surfaces. 
 
 The synovial capsules, which have been well described by Monro, are thin, transparent 
 membranes, forming shut sacs, which cover the heads of the bones without admitting 
 them into the interior of the cavity. In fact, it is their external surface which adheres 
 more or less intimately to the ligaments and other parts which surround the joint, while 
 their internal surfaces are in contact with each other, and are constantly lubricated by 
 the synovia. It is a question among anatomists whether the synovial membrane covers 
 also the articular cartilages. It can only be traced by the knife as far as the circumfer- 
 ence of these cartilages, and if it exists on them, which analogy would lead us to be- 
 lieve, it is so completely modified as not to be recognisable. Without admitting or de- 
 nying the fact, for the sake of facility in description, we shall assume the continuity of 
 this membrane over the cartilages. In many joints the synovial membrane is raised 
 from the surface of the parts by a subjacent cushion of fat, which projects into the joint, 
 and which Clopton Havers imagined to be a gland for secreting the s)Tiovia. I believe 
 that this, which may be called synovial fatty tissue, is only intended to fill up the spaces 
 which would otherwise be formed in many articulations during the performance of cer- 
 tain movements. The synovial fringes, described by the same author as the excretory 
 ducts of these glands, are nothing more than folds of the membrane. 
 
 Classification of the Joints. 
 
 The multiphcity of the articulations, and the analogies and differences which they 
 present, have induced anatomists to arrange them in a determinate number of groups, 
 having well-marked characteristics. The shape of the articulating surfaces in each 
 joint, the arrangement of the uniting media, and the variety and extent of motions, being 
 necessarily correlative, either of these three circumstances may be taken as the basis of 
 classification. Most of the older anatomists, attending specially to the means of union, 
 divided the articulations into four classes : 1 . Synchondroses {avv, with, and x6v6po(, a car- 
 tilage), when the bones are united by means of cartilage ; 2. Syneuroses {avv, with, and 
 vtvpov, a nerve, the synonyme of ligament among the ancients), when the connexion is 
 established by ligaments ; 3. Syssarcoses {avv, with, and aup^, flesh or muscle), those 
 joints in which muscles form the uniting medium ; 4. Meningoscs {fi^viy^, a membrane), 
 when membranes serve as ligaments, as in the bones of the cranium in infants. This 
 classification can only be regarded as a rough sketch. 
 
 Bichat, fixing his attention entirely upon the movements, has divided the movable 
 joints according to the variety of motions of which they are capable. There are four 
 kinds of motion : 1 . Gliding ; 2. The movement of opposition, when a bone is alternately 
 moved in opposite directions, as in flexion and extension ; 3. The movement of circum- 
 duction, when the bone which is in motion describes a. cone, the apex of which is at the 
 joint, and the base is traced by the opposite end of the bone ;* 4. The movement ofrotor 
 tion, in which a bone rolls on its axis without changing its place. 
 
 Proceeding on this classification of the movements, Bichat arranged the articulations 
 in two great classes, the movable and the immovable. The latter he divided accord- 
 ing to the nature of the articular surfaces, the former according to the number of mo- 
 tions, in the following order : 1st class, those joints which are capable of every kind of 
 motion, viz., gliding, opposition, rotation, and circumduction ; 2d class, those joints which 
 are capable of all the motions, excepting rotation ; 3d class, those joints which are only 
 capable of opposition, or alternate motions in the same plane ; ith class, those joints 
 which admit only of rotation ; 5th class, those joints which are only capable of a gliding 
 motion. We should observe that gliding occurs in all the preceding forms of articulation. 
 
 This classification, which is almost exclusively founded upon a consideration of the 
 movements, is eminently physiological. For this reason we shall reject it, because, in 
 the study of anatomy, the consideration of functions is of secondary importance, com- 
 pared to that of structure. The motions of a joint are also evidently the consequence 
 of the shape of its articular surfaces. 
 
 The classification now genercilly adopted is that of Galen, with some modifications. 
 Taking the presence or absence of mobility as the primary ground of division, the artic- 
 ulations are divided into the movable or diarthroses, and the immovable or synarthroses. 
 To these two great divisions Winslow has added a third, under the name of mixed artic- 
 ulations, or amphiarthroses {uji^u, both), because they partake of the characters of both,, 
 viz., mobility, and continuity of surfaces. + 
 
 For the determination of the secondary divisions, regard h£is been had both to tha 
 shape of the articular surfaces, and to the movements of which the joint is capable. 
 
 * All the joints which possess the four movements of opposition necessarily possess those of etrcumcvuctton; 
 t This kind of articulation was known to Galen, and named by him neuter, or doubtful articulation 
 
 P 
 
1 14 ARTHROLOGY. 
 
 Thus, the diarthroses hare been subdivided iiito, 1. Enarthroses, when the head of one 
 bone is received into the cavity of another ; 2. Arthrodia, when the articular surfaces are 
 plane, or nearly so ; 3. Ginglymus, when the joint is only capable of opposition, that is, 
 of alternate movements in opposite directions in the same plane. This latter class is 
 again subdivided into (a) angular ginglymus or hinge-joints, when the movements are an- 
 gular, as in flexion or extension : the angular ginglymus is said to be perfect, when these 
 movements alone are possible, as in the elbow ; and imperfect, when a slight degree of 
 later2d motion may take place, as in the knee : (Jb) lateral ginglymus (or diarthrosis tro- 
 choides), when rotation is the only possible movement. It also is subdivided into simple^ 
 when the bones touch only by one point ; and double, when they have two points of contact. 
 
 The synarthroses, or immovable joints, have been divided, according to the nature ot 
 their articular surfaces, into, 1. Suture, when they are furnished with teeth, by means ol 
 which they are locked together, as in the squamous suture ; 2. Harmonia, when the sur- 
 faces are nearly smooth, and are merely in juxtaposition ; 3. Gomphosis, when one part 
 is implanted in another, as the teeth in the alveoli ; 4. Schindylesis, when a plate of one 
 bone is received into a groove of another : in this way the osseous projection of the an- 
 terior edge of the palate bone is attached to the opening of the maxillary sinus.* 
 
 There are many advantages in the abov& classification, but many imperfections also. 
 I would characterize, as especially objectionable, the class arthrodia, which comprises 
 the most dissimilar articulations, as the shoulder-joint, the articulations of the lower 
 jaw, of the wrist, of the bones of the carpus, and of those of the tarsus. We should als9 
 notice, as another cause of imperfection, the want of imity in the basis of the classifi- 
 cation, which is sometimes founded upon the shape of the surfaces, sometimes on the 
 motions. 
 
 By adopting the shape of the articular surfaces alone as a basis, we shall find the ar- 
 rangement of the ligaments and the motions to be in some measure dependant upon this. 
 On this principle, we shall divide all the joints into three classes : 1. The diarthroses 
 {diapdpovj), or those which are formed by bones the surfaces of which are contiguous, 
 but free ; 2. Synarthroses {avv, with), or all the joints whose surfaces are continuous ; 
 3. Amphiarthroses, or symphyses (an<pu, both), or those joints whose surfaces are partly 
 contiguous, and partly continuous by means of fibrous tissue. 
 
 I. Diarthroses. 
 
 Characters. — Contiguous or free articular surfaces, shaped so as to fit exactly upon 
 each other, and each provided, 1. With an incrusting layer of cartilage ; 2. With syno- 
 vial membranes ; 3. With peripheral ligaments ; joints always movable. This class is 
 divided into six subdivisions : 
 
 1. Enarthrosis. 
 
 Characters. — A head, or portion of a sphere, more or less completely received into a 
 cavity. Examples : hip and shoulder joints (fig. 76, and^«. 69 and 70). 
 
 Ligaments. — A fibrous capsule. 
 
 Motions. — In every direction ; viz., flexion, extension, abduction, adduction, circumr 
 duetion, and rotation. 
 
 2. Articulation by mutual Reception. 
 
 Characters. — Articular surfaces, concave in one direction, convex in the direction per- 
 pendicular to the first, and so fitted as to embrace each other reciprocally. Example ; 
 articulation of the trapezium with the first metacarpal bone {m,fig. 75). J 
 
 Ligaments. — Two or four ligaments, or, rather, an orbicular or capsular ligament. 
 
 Motions. — In all directions, like the enarthroses, excepting rotation. 
 
 3. Articulation by Condyles, or Condylarthrosis. 
 
 Characters. — An elongated head, or condyle, received into an elliptical cavity. Ex- 
 amples : articulation of the forearm and hand {fig. 75), of the lower jaw and the temporal 
 bone {fig. 65). 
 
 Ligaments. — Two or four ligaments. 
 
 Motions. — In four directions ; viz., flexion, extension, abduction, and circumduction, 
 but no rotation. There are always two principal movements in these joints, and, con- 
 sequently, two which are limited. 
 
 4. Trochlear Articulation, or Ginglymus. 
 Characters. — A mutual reception of the articular surfaces. The pulley or trochlea 
 belongs to this mode of articulation. Examples : the elbow {figs. 71 and 72), the knee 
 {fig. 78), the joints of the phalanges {figs. 73 and 74). 
 
 * [The rostrum of the sphenoid, and the descending plate of the ethmoid, are united in this manner to the 
 vomer, and afford, perhaps, a better example.] 
 
 + The particle Ita always signifies separation. 
 
 i The cervical vrrtebrae of the swan present a beautiful specimen of this kind of articulation. This girei 
 to the movements of the neck of these birds that elegance and grace for which they are so remarkable. 
 
ARTICULATIONS OF THE VERTEBRAL COLUMN. Il6 
 
 Ligaments. — ^Two lateral ligaments generally placed nearer the side of flexion than 
 that of extension. Sometimes there are likewise anterior and posterior ligaments, but 
 they are always weak, and are often replaced by tendons. 
 
 Motions. — Two motions in opposite directions. 
 
 5. Trochoid Articulations.* 
 
 Characters. — An axis received into a ring, which is partly osseous and partly fibrous. 
 Examples : articulation of the atlas and axis (c, fig. 64), of the radium and ulna {figs. 71 
 and 72). 
 
 Ligaments. — ^An annular hgament. 
 
 Motions. — Rotation. 
 
 6. Arthrodia. 
 
 Characters. — Articular surfaces, plane, or nearly so.t Examples: articulations of the 
 carpal and tarsal bones {figs. 75 and 84), and of the articular processes of the vertebrae {g,figs. 
 61 and 63). 
 
 Ligaments. — Fibres placed irregularly round the joint. 
 
 Motions. — Gliding. 
 
 II. Synarthroses. 
 
 Characters. — Articular surfaces armed with teeth or other inequalities, which are mu 
 tually dovetailed, and from which the name of suture is derived. Examples : articular 
 tions of the bones of the cranium {figs. 21, 22, and 23). 
 
 Means of Union. — Remnant of the cartilage of ossification, which is gradually en- 
 croached on during the progress of age.J 
 
 There are no incrusting cartUages, synovial membranes, ligaments, nor motions. 
 
 Monro enumerates seven kinds of sutures, and these might still be multiplied, if we 
 regarded all the varieties presented by the articular surfaces. Three kinds may be ad- 
 mitted with propriety: 1. Indented sutures; 2. Squamous sutures; and, 3. Harmonic sv^ 
 tares ; the distinctions depending upon the articular surfaces being provided with teeth, 
 or overlapping like scales, or being simply rough and in juxtaposition. These even are 
 only unimportant varieties. Monro added the schindylesis, or ploughshare articulation 
 of Keil. We shall content ourselves with simply mentioning it ; and we also omit the 
 division gomphosis {yofK^oQ, a nail), which is appropriated to the mode of implantation of 
 the teeth ; because the teeth are not bones, and are lodged in the jaw, not articulated 
 with it. 
 
 III. ^mphiarthroses, or Symphyses. 
 
 Characters. — Flat, or nearly flat, articular surfaces, which are partly in contact, and 
 are partly continuous, by means of fibrous tissue. Examples : articulation of the bodies 
 of the vertebra {b, fig. 58), symphysis pubis {e, fig. 77), sacro-iliac symphysis {b, fig. 76). 
 
 Means of Union. — Interosseous and peripheral ligaments. 
 
 Motion. — Very slight, gliding ; an arthrodia is a necessary element of an amphiarthro- 
 »is. Thus, in the symphysis pubis the bones are partly in contact, partly continuous. 
 
 ARTICULATIONS OF THE VERTEBRAL COLUMN. 
 
 Articulations of the Vertebrae with each other. — Those peculiar to certain Vertebra:. — Sacro- 
 vertebral, Sacro-coccygeal, and Coccygeal Articulations. — Articulations of the Cranium — 
 Of the Face — Of the Thorax. 
 
 The articulations of the vertebral column {figs. 58, 59, and 60) are divided into the 
 extrinsic and the intrinsic. The first comprise the articulations of the vertebral column 
 with the head, the ribs, and the ossa innominata. The intrinsic comprise the articula- 
 tions of the vertebrae with each other. These last are also divided into those which are 
 common to all the vertebrae, and those which are peculiar to some. We shall describe 
 each in succession. 
 
 Articulations of the Vertebrcs with each other. 
 Mode of Preparation. — Remove completely all the soft parts which surround the ver- 
 tebral column ; saw ofl!" vertic2illy all that part of the head which is in front of the column, 
 and separate the bodies of the vertebra from the posterior arches by dividing the pedi- 
 cles. When the section reaches the axis, carry the instrument behind the superior ar- 
 
 * The trochoid (rpfx<u, to turn), or pivot-joint, corresponds to the simple or double lateral ginglymu* of' 
 modem anatomists, or the rotatory diarthrosis of the ancients. 
 
 t These articular surfaces are very variable in the arthrodial articulations. Sometimes they are angular, 
 sometimes spheroidal. As respects the ligaments, they are sometimes loose, sometimes firm. 
 
 t Some anatomists have rejected this kind of articulation, adopting the opinion of Columbus, who affirms 
 that there can be no joint whe'e there is no motion. 
 
116 
 
 ARTHROLOGY. 
 
 licular processes of this vertebra, and of the atlas, and behind the condyles of the occipi- 
 tal cone : remove the spinal marrow^ and its membranes. In this way the vertebral col- 
 umn will be divided into two parts : an anterior, formed by the series of the bodies of the 
 vertebra;, on which we find the anterior and posterior common ligaments, and the interver- 
 tebral substances ; and a posterior, formed by the series of laminae, and the articular and 
 sj)inous processes. The intervertebral substances require a special preparation, which 
 consists in making vertical and horizontal sections of a portion of the column, or which 
 may be more simply effected by maceration in diluted nitric acid, which allows the 
 bodies of the vertebra; to be removed without injuring the intervertebral substance. 
 The vertebrae are united, 1 . By their bodies ; 2. By their articular processes ; 3. By their 
 laminae ; and, 4. By their spinous processes. 
 
 Articulation of the Bodies of the Vertebra. 
 The bodies of the vertebrae are united together by amphiarthrosis. The arthrodial por- 
 tion, or the contiguous surface, is represented by the articular processes. 
 
 The articular surfaces are the upper and under surfaces of the body of each vertebra. 
 It follows, from the concavity of these surfaces, that, instead of fitting each other exact- 
 ly, they leave considerable lenticular spaces between them ; these appear to berfhe ves- 
 tiges of the biconical cavity between the vertebrae of fishes. The depth of these spaces 
 is not the same throughout the entire column ; it exactly measures the thickness of the 
 intervertebral substance. By measurement, I have afecertained that the height of the in- 
 tervertebral substance in the loins is one half of that of the bodies of the vertebra, in the 
 back one third, and in the neck a little more than the half From the size of the bodies 
 of the vertebra, it follows that the interval between the bodies is largest in the lumbar re- 
 gion. The articular surfaces of the bodies of the vertebra are covered by a very thin 
 layer of cartilage intermediate between the bones and the fibrous tissues. 
 
 The means of union are of two kinds, as in all the amphiarthroses : 1. They surround 
 the joint ; 2. They proceed from one articular surface to the other : in one word, some 
 are peripheral, and the others interosseous. 
 
 1. Peripheral Ligaments. — The most general idea which can be formed of these liga- 
 ments is that of a fibrous sheath, surrounding the column formed by the bodies of the 
 vertebrae, and uniting in one whole the different pieces of which it is composed. The 
 part of the sheath which covers the anterior aspect of the bones is called the anterior 
 common ligament of the vertebra ; and that which covers the posterior surface is called 
 the posterior common ligament of the vertebra. 
 
 The anterior common vertebral ligament (a, figs. 58, 60) presents the appearance of a 
 Fig. 58. white pearly-looking membrane stretched from the axis to the 
 
 upper part of the sacrum. This ligament, which is thicker in the 
 dorsal region than in the neck or the loins, is composed of three 
 very distinct parts : a thick one in the middle, and two lateral, 
 which are separated from it by a series of openings that give pas- 
 sage to some vessels (see fig. 58). Its anterior surface is in con- 
 tact with the organs of the neck, the thorax, and the abdomen, 
 and united with them by very loose cellular tissue. The tendons 
 of the longi colli and anterior recti muscles, and the pillars of the 
 diaphragm, mix their fibres with this ligament. The psoae mus- 
 cles correspond to its lateral portions below. Its posterior surface 
 adheres more closely to the intervertebral substances, and to the 
 projecting rims of the bodies of the vertebrae, than to the trans- 
 verse grooves of the bodies. This ligament is composed of sev- 
 eral planes of fibres, of which the most superficial are the longest. 
 The deepest pass from one vertebra to the next, and are lost on 
 the periosteum. The superficial stretch over four or five vertebrae. 
 
 Posterior common vertebral ligament (a, fig. 59). This is thicker than the anterior, but 
 
 (Fig. 59.) 
 
 has the same white pearly appearance. It commences at the oc- 
 cipital bone, and terminates at the sacrum. It resembles a fibrous 
 band, which expands at the intervertebral substances, and is con- 
 tracted over the bodies of the vertebrae ; hence it has a regular fes- 
 tooned appearance. Its posterior surface is united to the dura mater 
 at its upper part, but is separated from it by a dehcate cellular tis- 
 sue throughout the rest of its extent. Its anterior surface adheres 
 intimately to the intervertebral substances ; it is separated from 
 the middle of the bodies of the vertebra by the veins, which pass 
 from the interior of the bone into the vertebral venous sinuses 
 which run along the edges of the ligament. Like the anterior com- 
 mon vertebral ligament, it is composed of several planes of fibres, 
 the posterior of which are the longest. It is formed of more com- 
 pact tissue than the anterior. 
 2. The intervertebral substance or interosseous hgament {b, figs. 58, 
 
ARTICULATIONS OP THE VERTEBRAL COLUMN. 117 
 
 59, 60, and 68) consists of a kind of disc, which fills up the lenticular space between the 
 bodies of the vertebrae, and might, with propriety, be called mtervertehrd. disc. 
 
 Each disc has the form of a double convex lens, and is so closely united by its upper 
 and under surfaces to the corresponding vertebra;, that it is easier to break the bones than 
 to destroy this connexion. Its circumference adheres to the anterior and posterior com- 
 mon ligaments, and contributes to form the intervertebral foramina. In the dorsal region 
 it also forms part of the angular facette which articulates with the ribs. The thickness 
 of the intervertebral substance is not the same in all the regions of the spinal column, be- 
 ing greatest at the lower parts. The proportion between the thickness of the discs and 
 the bodies of the vertebrae is exactly measured by that of the intervertebral space, and is 
 not the same in all the regions. In the lumbar region the thickness of the disc is half 
 that of the corresponding vertebrae ; in the dorsal region it is a third ; and in the cervi- 
 cal region it is a little more than a half* 
 
 The intervertebral substance is not equally thick throughout. From its lenticular form, 
 it must be thicker at the centre than at the circumference ; in the neck and in the loins 
 it is thicker in front than behind ; in the back the opposite prevails, and by this inequality 
 the discs concur in producing the alternate curves of the vertebral column. Abnormal 
 curvatures are in a great measure caused by unequal thickness of these dies, and I have 
 often had opportunities to convince myself that compression of this substance on the side 
 towards which the inclination takes place is the most common origin of the deformity. 
 The thickness of the discs varies in different circumstances. Thus, after prolonged 
 standing in the erect posture, the height of the body becomes diminished from eight to 
 ten lines, which is owing to compression of the intervertebral substances. 
 
 Each disc is composed of concentric layers (figs. 60 and 68) closely pressed together 
 at the circumference, but more separate towards the centre, where we find a soft spongy 
 substance, moistened by a viscid fluid resembling synovia. This soft substance is nearer 
 the posterior than the anterior aspect of the body of the vertebra ; it escapes, and forms, 
 as it were, a hernia, when the parts are cut either horizontally or vertically. It varies 
 much at different ages. It is moist, soft, spongy, and white in the infant and in youth, 
 which accords with the suppleness of the vertebral column at that period of life. Where 
 this substance is situated, we may inflate an irregular cellular cavity in it, which may be 
 regarded as the rudiment of the large synovial cavity which these parts exhibit in fishes. 
 M. Pailloux believes that this cavity is lined by a synovial membrane. In old age it be- 
 comes dry, friable, and yellowish, or brown. Monro attributes the elasticity of the ver- 
 tebral column to the displacement of this soft central substance in the different move- 
 ments ; for, according to his theory, the movements of the bodies of the vertebrae take 
 place upon it as upon a movable pivot or a Uquid fulcrum. 
 
 The intervertebral substance is called a cartilaginous ligament by Vesalius ; by others, 
 a cartilage ; and by Bichat, a Jibro-cartilage ; but they evidently belong to the fibrous tis- 
 sues. This may be shown by macerating a portion of the spinal column for some days, 
 or even by rubbing the surface with a rough cloth. It will then appear that this pretend- 
 ed fibro-cartilage is nothing more than a series of concentric fibrous layers, strongly com- 
 pressed together ; that each layer is formed of parallel fibres, directed very obliquely 
 from the lower surface of the vertebra above to the upper surface of the vertebra below, 
 and regularly crossing with the fibres of the next layer {¥, fig. 58). This regular cross- 
 ing, which we shall meet with in other parts, is evidently very conducive to solidity. 
 
 Union of the Articular Processes. 
 
 These articulations are arthrodice. 
 
 Articular Surfaces. — The corresponding surfaces are covered by a thin layer of cartilage. 
 The means of union consist of some irregular ligamentous fibres {d d, fig. 60), which sur- 
 round the outside of the joint, and are more numerous in the dorsal and cervical regions 
 than in the loins, the internal side of the articulation being occupied by the yellow liga- 
 ment. These articulations are provided with synovial membranes of greater extent in 
 the cervical than in the other regions. 
 
 Union of the LamincB. ^_ 60. 
 
 The spaces between the vertebral laminae are occupied by ligaments of 
 a particular description, which are called yellow ligaments, ligamenta suh- 
 flava, on account of their colour. They are composed of two halves uni- 
 ted at an angle like the laminae (c c,fig. 60). Their lower edge is implanted 
 upon the upper edge of the laminae below, and their upper edge is attached 
 to the anterior surf£ice of the corresponding laminae. From this it fol- 
 lows, that the height of the ligamenta subflava is much greater than would 
 be necessary to reach from one lamina to another ; it is almost equal 
 to that ol the corresponding vertebral lamina. 
 
 Their length is measured by that of the laminae, and is, consequently, 
 
 * A curious preparation may be made by taking away all the bodies of the vertebrae in a 
 spine softeced by nitric acid. A column then remains, formed by the series of discs, which 
 may be compared with a column formed by the bodies of the vertebra;. 
 
118 ARTHROLOGY. 
 
 greater in the neck than in the back and loins. They are of greater thickness in the 
 loins than in the back and the neck, and the thickest part corresponds to the base of the 
 spinous process. There are also some re-enforcing bundles, which constitute a sort of 
 median yeUow ligament. Their anterior surface is separated from the dura mater by cel- 
 lular tissue, and by veins. It is remarkable for its smooth and polished appearance. 
 Their posterior surfaces are in contact with the vertebral laminae, which cover them al- 
 most completely, except in the cervical region, where they may be seen between the lam- 
 inae, when the head is slightly inclined forward ; this circumstance renders it possible 
 lor a penetrating instrument to enter between the cervical laminae, while it is almost 
 impossible in the dorsal and lumbar regions. 
 
 Structure. — These ligaments are composed of parallel vertical fibres very closely ar- 
 ranged. They are extensible, and, when stretched, immediately recover themselves, and 
 are therefore very elastic. They are as strong as ordinary ligaments. Their extensi- 
 bility is brought into action during flexion of the vertebral column, and their elasticity 
 during extension. They have great effect in maintaining the erect posture, which would 
 otherwise have required a constant expenditure of muscular power. 
 
 Union of the Spinous Processes. 
 
 The spinous processes are united by the supra-spinous and the inter-spinous ligaments. 
 The supra-spinous ligament {d d, figs. 58 and 59) is a fibrous cord, which extends from the 
 seventh cervical vertebra to the sacrum, along the summit of the spinous processes of 
 the dorsal and lumbar vertebrae. This ligament can be only distinguished from the 
 aponeurotic fibres, which are inserted into the spinous processes, by the longitudinal di- 
 rection of its fibres. It is larger in the lumbar than in the dorsal region. It is expand- 
 ed, and becomes even sometimes cartilaginous in the interval between the processes. 
 It is inextensible. I regard a fibrous cord which extends from the seventh cervical ver- 
 tebra to the external occipital protuberance as a continuation of the supra-spinous liga- 
 ment ; it appears to be the vestige of the posterior cervical ligament of quadrupeds, and is 
 of considerable size in some subjects ; from its anterior surface, prolongations a\^ given 
 off to the spinous processes of all the cervical vertebrae, excepting the first.* 
 
 The inter-spinous ligaments (e e, Jig. 58) do not exist in the neck, where their place is 
 suppUed by small muscles ; they are very thin in the back, where each has the form of a 
 triangle with the base looking backward. They are thick and quadrilateral in the loins. 
 Their upper and lower edges are attached to the corresponding spinous processes. Their 
 surfaces are in contact with the muscles of the vertebral grooves. M. Mayer speaks of 
 synovial capsules, which he has met with between the lumbar spinous processes, and 
 especially between the third and the fourth in this region ; these membranes are by no 
 means constant. 
 
 Articulations peculiar to certain Vertebra (Jigs. 61 to 64). 
 
 Although the articulations of the atlas and of the axis, with the occipital bone, do not 
 properly belong to the articulations of the vertebral column, yet the connexion between 
 these articulations and that of the atlas with the axis is so intimate, that it is impossi- 
 ble to separate them. We shall describe these three articulations in succession ; first 
 noticing the articulation of the atlas with the occipital bone {occipito-atlantoid articulation). 
 
 Occipito-atlantoid Articulation. 
 
 Preparation. — Remove the part of the scull which is in front of the vertebral column, 
 taking care to leave the basilar process. The muscles which surround the joint, being 
 closely applied to the ligaments, should be very carefully detached. 
 
 The atlas unites with the occipital bone, 1 . By its anterior arch ; 2. By its posterior 
 arch ; 3. By the base of its transverse processes ; 4. By its two articular surfaces. 
 1. The anterior arch of the atlas is united to the circumference of the foramen mag- 
 „. g. num by two anterior occipito-atlantal ligaments. One 
 
 *^' ■ of these, the superficial (a, figs. 61 and 64), is a very 
 
 strong cylindrical cord situated in the median line, 
 where it forms a very marked projection, and stretches 
 from the basilar process of the occipital bone to the an- 
 terior tubercle of the atlas. The other (i, fig- 61), 
 which is deep-seated, is pretty thick, consists of several 
 layers, and extends from the upper edge of the anterior 
 arch of the atlas to the occipital bone. 
 
 2. Most anatomists admit the existence of a liga 
 ment stretching from the posterior part of the foramen 
 magnum to the upper edge of the posterior arch of the 
 atlas, the posterior occipito-atlantal ligament (b, figs. 62 
 
 * This ligament is the result of the intersection of the aponeuroses, of the trapezius, splenius, &c. I shall 
 »fer more particularly to this point in myology, when on the subject of the posterior cervical apoueiirosis 
 
ARTICULATIONS OF THE VERTEBRAL COLUMN. 
 
 119 
 
 and 64). But it can scarcely be distinguished, con- Fig. 62. 
 
 sisting only of a {ew ligamentous fibres among the 
 fat of this region. 
 
 3. Lateral Occipito-atlantal Ligaments (c, jig. 61). 
 — A fibrous cord passes from the base of the trans- 
 verse process of the atlas to the jugular process of 
 the occipital bone. In connexion with a similar bun- 
 dle from the pars petrosa, it forms a very remark- 
 able fibrous canal, which gives passage to the in- 
 ternal jugular vein, the internal carotid artery, the 
 hypoglossal, pneumogastric, glosso-pharyngeal, and 
 accessory nerves. 
 
 4. The union of the condyles of the occipital bone with the superior articular surfaces 
 of the atlas is a double candy laid articulation. The articular surfaces of the occipital bone 
 are the two condyles, convex, oblong, looking downward and outward, and directed for- 
 ward and inward, so that their axes, if prolonged, would meet in front of the basilar 
 process. The articular surfaces of the atlas are concave and oblong, and look upward 
 and a little inward, so as to fit exactly upon the convexity of the condyles. Both are 
 covered by a thin layer of cartilage. The ligaments are vertical fibres which surround the 
 joint, but are most numerous in front and on the outside, for they scarcely exist on the 
 mside and behind. There is also a very loose synovial membrane which passes beyond 
 ^he articular surfaces on all sides, but especially to the outside. 
 
 Atlanto-axoid Articulation. 
 
 Preparation. — After having studied the superficial ligaments, remove the laminae of the 
 axis, the posterior arch of the atlas, and the back part of the foramen magnum. Detach 
 with care that portion of the dura mater which corresponds to the first two vertebrae and 
 the foramen magnum, and turn it upward. Lastly, in order to obtain a good view of the 
 articulation of the odontoid process with the atlas, disarticulate the occipital bone. 
 
 This articulation is formed between, 1. The odontoid process of the axis, and the an- 
 terior arch of the atlas ; 2. Between the superior articulating processes of the axis and 
 the inferior articulating processes of the atlas ; 3. In addition, the anterior and posterior 
 arches of the atlas are united to the Jixis by two hgaments — the anterior and the poste- 
 rior atlanto-axoid ligaments. 
 
 The anterior atlanto-axoid ligament {b,figs. 61 and 64) is a thick vertical bundle com- 
 posed of several layers, which extends from the tubercle and the lower edge of the an- 
 terior arch of the atlas in front of the base of the odontoid process of the body of the axis. 
 It is continuous below with the anterior common ligament. 
 
 The posterior atlanto-axoid ligament (c,figs. 62 and 64) is a very loose and thin mem- 
 brane, extending from the posterior arch of the atlas to the upper edge of the laminae of 
 the axis ; it is a little thicker in the median hue than at the sides, and represents the 
 ligamenta subflava in a rudimentary state. 
 
 Articulation of the Odontoid Process with the Atlas. — This is aywof joint, the odontoid pro- 
 cess being received into a ring formed in front by the anterior arch of the atlas, on the 
 sides by the lateral masses of the same bone, and behind by the transverse ligament. 
 We have, therefore, to consider, 1. The articulation of the anterior arch of the atlas with 
 the odontoid process (atlanto-odontoid articulation) ; 2. The articulation of this same pro- 
 cess with the transverse ligament (syndesmo-odontoid articulation). 
 
 1. Atlanto-odontoid Articulation (e, fig. 64). — The articular surfaces are an oval and 
 slightly concave facette on the posterior surface of the anterior arch of the atlas (1); 
 and a slightly convex, vertically oblong facette, on the fore part of the odontoid process 
 (2). Both surfaces are incrusted with cartilage, and there is also a very loose synovial 
 membrane with subjacent adipose tissue. The joint is strengthened by some hgament- 
 ous fibres, arranged in the form of a capsule. 
 
 2. Syndesmo-odontoid Articulation. — ^This joint is formed by means of the transverse or 
 
 Fig. 63. 
 
 annular ligament (/, figs. 63 and 64), a very thick and 
 compact bundle of fibres, flattened before and behind, 
 and stretched transversely between the lateral masses 
 of the atlas, passing behind the odontoid process, and 
 closely embracing it like a half ring. The anterior sur- 
 face of this hgament is concave, and polished like car- 
 tilage ; it is in contact with the posterior surface of 
 the odontoid process (2, fig. 64), which is covered with 
 cartilage, and is almost always furrowed transversely, 
 i. e., in the direction of its movements. There is a very 
 loose synovial membrane in this joint, which is prolonged on the sides of the odontoid 
 process, as far as the odontoid ligaments. The posterior surface is covered by the pos- 
 terior occipito-axoid ligaments* (o, fig 64 ; see figs. 63 and 64). From its upper edge a 
 
 * If the student is only provided with one preparation for the examination of all these joints, it is necessary 
 «o study these ligament* before dividing them, in order to expose the transverse lig-aiuenls. 
 
120 ARTHROLOGY. 
 
 fibrous band is detached, which is fixed to the occipital bone, in front of the occipito-ax- 
 oid ligament, by a narrow extremity. Another fibrous band (see jigs. 63 and 64), of 
 greater length than breadth, proceeds from its lower edge, and is attached to the postenor 
 surface of the axis ; hence the name crucial has been given to the annular ligament by 
 some authors. The extremities are inserted into two tubercles on the inside of the 
 lateral masses of the atlas. 
 
 There is a very remarkable circumstance connected with this ligament, viz., that its 
 lower circumference belongs to a smaller circle than its iipper, so that the odontoid process 
 is very firmly retained in the ring which this ligament contributes to form, and this ar- 
 rangement accords with a sort of constriction at the base of the odontoid process. 
 
 Union of the Articular Processes of the Atla^ and the Axis. 
 This is a double arthrodia. The articular stirfaces of the atlas are plane, circular, and 
 horizontal, but looking slightly inward ; those of the axis are also plane and horizontal, 
 looking slightly outward, and of greater extent than the preceding. They are retained 
 in their place by a fibrous capsule ig,figs. 61 and 63), which is very strong, especially in 
 front, and sufficiently loose to permit the extensive motions which take place at this 
 joint : it is formed of vertical and parallel fibres. The synovial ca-psule is very loose, and 
 projects beyond the surfaces of the bones in every direction, but particularly in front. It 
 almost always communicates with the synovial membrane of the joint between the 
 transverse ligament and the odontoid process. 
 
 Union of the Occipital Bone and the Axis. 
 
 Although the occipital bone and the axis are nowhere contiguous, and are not, there- 
 fore, articulated, yet they are united very firmly by means of strong ligaments, extending 
 from the occipital bone to the body of the axis, and also to the odontoid process. 
 
 Preparation. — Remove with care that portion of the dura mater which corresponds to 
 the first two vertebrae ; the occipito-axoid ligaments lie under it. Then detach the 
 transverse ligaments, remove the anterior arch and lateral masses of the atlas, so that 
 nothing remains excepting the occipital bone and the axis. 
 
 1. The occipito-axoid ligaments are three in number, a middle and two lateral. The 
 Ftg. 64. middle occipito-axoid ligament (o, fig. 64) is thick, and forms 
 
 at its upper part a single band, the fibres of which are sep- 
 arated below into three very distinct layers. The most 
 posterior of these is continuous with the posterior common 
 ligament ; the second is attached to the posterior surface 
 of the body of the axis ; and the deepest, which is very 
 thin, and shaped like a tongue pointed above, is that which 
 we described with the transverse ligament. The lateral 
 occipito-axoid ligaments (r, fig. 64) arise from the sides of 
 the basilar groove by a broad extremity, and are attached 
 to the posterior surface of the axis by a pointed end. They 
 
 correspond in front with the odontoid and transverse ligaments, and behind with the 
 
 dura mater. 
 
 2. The odontoid ligaments are three in number, a middle and two lateral. The middle 
 (I, fig. 64) consists of ligamentous fibres, which extend from the apex of the odontoid 
 process to the fore part of the foramen magnum, between the condyles ; the two lateral 
 (I, fig. 63) are two bundles of fibres, very strong, short, and cylindrical, which stretch 
 between the sides of the apex of the odontoid process, and two small fossae on the inside 
 of the condyles ; their direction is horizontal, so that they represent the horizontal limbs 
 of the letter T, of which the odontoid process forms the vertical portion ; they are almost 
 always united by a bundle, which passes above the odontoid process without adhering to 
 it, so that, at first sight, they might be declared to be one and the same ligament. 
 
 Sacro'Vertebral, Sacro-coccygeal, and Coccygeal Articulations. 
 
 Sacro-vertebral Articulation. — This resembles in every point the articulations of the 
 other vertebra;. We shall only remark, 1 . The great thickness of the intervertebral sub- 
 stance, particularly in front, a vertical section of it resembling a hatchet with the broad 
 part turned forward ; 2. The sacro-vertebral ligament {a, fig. 76), which is proper to this 
 articulation, a very short, thick, and strong bundle stretched obliquely from the trans- 
 verse process of the fifth lumbar vertebra to the base of the sacrum, where it crosses 
 with some ligamentous fibres of the sacro-iliac articulation. 
 
 Sacro-coccygeal Articulation. — This is an amphiarthrosis, or symphysis, analogous in 
 every repect to that of the bodies of the vertebrae ; a fibrous disc resembling the inter- 
 vertebral substances, but of a more loose texture, unites the corresponding articular sur- 
 faces. In some subjects the coccjrx is very movable, and there is a synovial capsule in 
 the centre of the disc. The other means of union are, 1. The anterior sacro-coccygeal lig- 
 ament {a fig. 77), composed of parallel fibres extending from the anterior surface of the 
 sacrum to the anterior surface of the coccyx, and often divided into two lateral bundles ; 
 
MECHANISM OF THE VERTEBRAL COLUMN. 121 
 
 2. The posterior sacro-coccygeal ligament, which is fixed above to the edges of the notch 
 which terminates the sacral canal, and is prolonged upon the posterior surface of the 
 coccyx. This ligament, which completes the sacral canal, gives attachment to the glu- 
 taei maximi muscles by its posterior surface. It is composed of several layers, the most 
 superficial of which reach the apex of the coccyx, while the deepest extend only to the 
 first piece of that bone. 
 
 The coccygeal articulations are also amphiarthroses, which become synarthroses during 
 the progress of life. The articulation of the first with the second piece is the only one 
 . which remains to an advanced age. It is sometimes extremely movable.* 
 
 Mechanism of the Vertebral Column. 
 The vertebral column being at once an enclosing and protecting cylinder for the spi- 
 nal marrow, a column for transmitting the weight of the trunk and the upper extremi- 
 ties to the legs, and an organ of locomotion, its anatomical structure must be examined 
 in reference to these three uses. 
 
 The Vertebral Column considered as the Protecting Cylinder of the Spinal Cord. 
 The vertebral column performs the office of a protecting cylinder, by virtue of its so- 
 lidity, ensured by the bodies of the vertebrae in front, by the projection of the spinous 
 processes behind, which ward off, so to speak, all external objects, and by the promi- 
 nence of the transverse processes at the sides. By means of these arrangements, the 
 spinal cord is inaccessible, excepting by a sharp instrument, which might penetrate ei- 
 ther in front through the intervertebral substances, or on the sides through the interver- 
 tebral foramina, or, lastly, behind through the intervals between the spinous processes, 
 and between the laminae. Another condition of solidity, in so far as this can be obtain- 
 ed with mobility, is provided by the number of pieces of which the vertebral column is 
 formed. For, in all cases where the column is subjected to shocks, each articulation 
 becomes the seat of a decomposition of the force ; a part is employed in producing a 
 slight displacement of the articular surfaces, and is therefore entirely lost, as far as re- 
 gards the transmission of the shock. If, on the contrary, the vertebral column had been 
 formed of one single piece, the transmission of shocks would have been unbroken, and 
 thus the frequent cause of concussion and fracture. Lastly, the breadth of the articular 
 surfaces by which the bodies are united, the strength and pliability of the intervertebral 
 substances, the vertical direction of the articular processes, contrasted with the horizon- 
 tal direction of the articular surfaces of the body, and the species of dovetailing which 
 results from it, are also most favourable conditions for the protection of the spinal mar- 
 row. Indeed, I do not see how, in our system of organization, the protection to the spi- 
 nal cord could be increased. 
 
 • The Vertebral Column considered as an Organ for transmitting the Weight of the Trunk 
 The anatomical arrangements adapted to this purpose are the following : 
 
 1. The progressive increase in size of the vertebral column, from the apex to the base. 
 This disposition is particularly observable in the first two pieces of the sacrum, which 
 are proportionally much larger in man than in the lower animals. 
 
 2. The articulation of the vertebral column with the posterior part of the pelvis, by 
 which the centre of gravity of the trunk is carried backward, and the maintenance of 
 the equilibrium is aided, by counterbalancing the weight of the thoracic and abdominal 
 viscera, which, instead of uniformly surrounding the column, are all placed in front. 
 
 3. The alternate inflections of the vertebral column, which allow more extensive os- 
 cillations of the centre of gravity of the column than would have been practicable held 
 its direction been altogether rectilinear, and which also augment its power of resistance 
 in the vertical direction. 
 
 4. The length of the spinous processes, which thus afford a more favourable, because 
 a longer lever to the extensor muscles, which maintain the column erect. The absence 
 of these processes in infancy is one of the causes of the difficulty of standing at that period. 
 
 5. The existence of the soft matter in the centre of the intervertebral discs, which 
 prevents compression of the column by affording a liquid, and therefore almost incom- 
 pressible point d'appui, as Monro has remarked ; the truth of this may be proved by sub- 
 mitting a portion to powerful compression. We have before remarked that this soft 
 matter is not placed in the centre, between the bodies of the vertebra, but nearer to the 
 posterior border, and, consequently, it occupies the centre of their movements. It di- 
 minishes the violence of shocks, changes its position as we change our attitudes, and fills 
 up the vacancies resulting from the approach of the bodies on one side, and their separa- 
 tion on the other. It is generally believed, it is true, that the diminution of height which 
 follows upon prolonged standing or walking is the result of mechanical compression of 
 the intervertebral discs, and an absolute diminution of their thickness ; but it appears 
 
 * I have met with an instance in which this joint was very movable : there was a synovial membrane ana 
 a fibrous capsule. The extent of the motion was so great, that the two pieces could be made to form a, ngut 
 angle with the cavity looking backward. 
 
 Q 
 
122 ARTHROLOGY. 
 
 more conformable to the laws of physics to admit that the diminution in the height of 
 the vertebral column depends upon the increase of the curvatures, unless we admit Mon- 
 ro's hypothesis of the absorption of part of the hquid contained within the discs. 
 
 6. The presence of the yellow ligaments, which, by their elasticity, continually oppose 
 the causes which tend to bend the body forward, and which are for each of the vertebrae 
 what the posterior cervical ligament is for the head. 
 
 7. The existence of the vertebral canal, which has the same advantage as the cylinder 
 of long bones, of increasing the strength without increasing the weight. 
 
 8. The mode of articulation of the vertebral column with the head, which is doubly ad- 
 vantageous, both as regards the place occupied by the articular surfaces, and their di- 
 rection : 1. The articular surfaces correspond to the point of junction of the posterior 
 with the two anterior thirds of the head. The posterior third of the head contains a 
 large portion of the encephalic mass, while the two anterior thirds are chiefly formed by 
 the face, which, in comparison to its size, is of little weight. From this it follows, that 
 the weight of the posterior third almost counterbalances that of the two anterior thirds 
 of the head. 2. The almost horizontal direction of the condyles in the human subject 
 permits the head to rest upon the summit of the vertebral column, without having a 
 necessary tendency, or at least a very slight one, to incline forward, as invariably takes 
 place in animeds whose occipital condyles are vertical, and situated entirely on the back 
 of the head. Yet, notwithstanding these advantageous conditions of the atlantal artic- 
 ulation, the part in front of the condyles is somewhat heavier than that behind ; and this 
 difference, though slight, is sufficient to cause flexion of the head, when left to itself, 
 either during sleep or after death. Indeed, in spite of all the arrangements above re- 
 ferred to, considerable efforts are required to maintain the biped position ; and to secure 
 this, we have the vertebral grooves filled up with powerful muscles. In the human sub- 
 ject, the muscles which occupy the cervical portion of the column, and which are des- 
 tined to support the head, are not nearly so strong as the corresponding muscles in the 
 quadruped, while those of the loins are proportionally much stronger. Standing in the 
 erect position is, therefore, very far from being a state of rest, and requires a constant 
 muscular effort to sustain it. 
 
 The Vertebral Column considered as an Organ of Locomotion. 
 
 The vertebrae perform upon each other certain oscillatory or balancing movements in 
 all directions, by means of the pliability of the intervertebral substances ;* but they are 
 so obscure, that their existence can scarcely be recognised, or their character examined 
 on a small portion of the column. In order to understand them, the entire spine must 
 be examined. 
 
 Movements of the entire Column. — These are, 1. Flexion, or the movement forward. 2. 
 Extension. 3. Lateral inclination. 4. Circumduction, in which the column describes a 
 cone, of which the apex is below, and the base above. 5. Rotation on its axis, or tor- 
 sion of the vertebral column. 
 
 In the analysis of the motions of the column, it is necessary to distinguish carefully 
 between the actual and the apparent motions ; the first are much less extensive than 
 would be imagined at first sight, the greater part of the apparent movements taking place 
 at the articulations of the pelvis with the thighs. In these movements of the whole, the 
 column represents a lever of the third order, an elastic arch in which the resistance is at 
 the upper extremity, the fulcrum at the lower end, and the power applied in the middle. 
 Each vertebra, on the contrary, represents a lever of the first order, in which the pow- 
 er and the resistance are at the anterior and posterior extremities of the bone, and the 
 fulcrum in the middle. 
 
 1. In the movement of flexion, which is the most extensive of all, the anterior common 
 ligament is relaxed ; the anterior part of the intervertebral substances is compressed ; 
 the soft central portion is pushed backward ; the posterior fibres of the discs are shght- 
 ly stretched, as are also the posterior common ligament, the supra-spinous, inter-spi- 
 nous, and yellow ligaments. The inferior articular processes of each vertebra move up- 
 ward upon the superior articular processes of the vertebra below. The laminae are sep- 
 arated, so that the rachidian canal, especially in the cervical region, becomes accessible 
 to penetrating instruments. 
 
 2. In extension, the anterior common ligament and the anterior fibres of the intei ver- 
 tebral discs are stretched ; the posterior fibres of the disc are relaxed ; the soft central 
 matter is pushed forward ; the yellow, supra-spinous, and inter-spinous ligaments are 
 relaxed. The lower articular processes glide downward upon the superior articular pro. 
 cesses of the vertebra below. This motion is not extensive ; it is limited by the ante- 
 rior common ligament, and the meeting of the spinous processes. 
 
 3. In the movements of lateral inclination, the discs are compressed on the side to 
 which the inclination takes place, and the central pulp is forced to the other side. These 
 motions are limited, not only by the meeting of the transverse processes, but even be 
 
 * Tbns the uniting media of the vertebrse serve also as means of Icomotion. 
 
MECHANISM OF THE VERTEBRAL COLUMN. "HSl 
 
 fore these touch, by the resistance of the intervertebral substances, and of the lateral 
 bundles of the anterior common ligament. 
 
 4. Circumduction. — This motion, the centre of which is in the lumbar region, appears 
 at first sight very extensive, because a portion of the movement at the hip-joint is gen- 
 erally ascribed to it. In reahty, it is very limited, and results from a succession of the 
 preceding motions. 
 
 5. The movement of rotation is effected by the twisting of the intervertebral sub- 
 stances. Although the motion of each disc is very slight, yet the simultaneous twisting 
 of them all produces a general movement, by which the anterior surface of the column 
 is turned slightly to the sides. It is, however, upon the whole, very limited ; and al- 
 though in the erect posture the trunk of the body can describe a semicircle, the greater 
 part of this motion takes place at the hip-joint. 
 
 All the regions of the vertebral column do not equally participate in these general mo- 
 tions. They are most extensive in the cervical region, where we observe, 1. Flexion, 
 which may be carried so far as to make the chin touch the upper part of the sternum ; 
 2. Extension, so that the neck may be turned backward ; 3. Lateral inclination, until the 
 head nearly touches the shoulder ; 4. Rotation, which is greater here than in any of the 
 other regions, notwithstanding the presence of the lateral hook-like processes or ridges.* 
 Tliese motions may be to such an extent as to cause luxation, which can only take place, 
 without fracture, in the cervical region, on accoimt of the ahnost horizontal direction of 
 the articular processes. 
 
 The general movements are most limited in the dorsal region. 1. Flexion is rendered 
 impossible by the presence of the sternum. The presence of this bone in the different 
 species of animals attests the immobility of the dorsal portion of the column, in the same 
 manner as its absence is an indication of its mobility. 2. Extension is prevented by the 
 meeting of the spinous processes, which are longer and more closely imbricated in this 
 than in any other of the regions. 3. Lateral movements are rendered impossible by the 
 ribs, which would be forced against each other if this motion took place. 4. As aU the 
 preceding motions are the elements of circumduction, it may be easily conceived that 
 this can scarcely take place. 5. The same obstacles oppose the movement of rotation, 
 which is also prevented by the position of the articular processes, which are directed ver- 
 tically, and whose surfaces on the right and left sides are not upon the same plane. The 
 thinness of the intervertebral substances in the dorsal region accords with all these 
 arrangements in limiting mobility. 
 
 What has been said regarding the immobility of the dorsal region applies only to the 
 upper part of this region. The dispositions at the lower part are more favourable to mo- 
 bihty. We know that the last two dorsal vertebrae are remarkable for the shortness of 
 their spinous and transverse processes ; and that the ribs with which they articulate are 
 very movable, and could not oppose the motions of the vertebras in any degree. 
 
 The lumbar region participates much more in the general motions than the dorsal. 
 The articular processes in this region are much more advantageously adapted for rota- 
 tion than in either the dorsal or cervical, for the lower pair of each vertebra forms a solid 
 cylinder, which is received into the hollow surface of the superior articulating processes 
 of the vertebra below. This arrangement permits a motion resembhng that of the hinges 
 of a door. 
 
 It should be remarked, that in all the regions the lower articular processes of each 
 vertebra are placed behind the superior articular processes of the succeeding vertebra, 
 ftnd form a sort of imbrication. Each vertebra, then, is retained in its place by a species 
 of dovetailing, so that it cannot be dislocated forward without breaking the superior ar- 
 ticular processes of the vertebra below, nor backward, without breaking the inferior ar- 
 ticular processes of the vertebra above. This remark does not apply rigorously to the 
 cervical region, the articular processes of which are oblique, and can permit dislocation 
 ■without fracture. 
 
 Mechanism of the Articulations of the Vertebral Column and the Head. 
 The movements of the head upon the vertebral column are shared between two artic- 
 ulations : viz., 1. The occipito-atlantal, to which edl the motions of flexion, extension, 
 lateral inclination, and circumduction belong ; 2. The atlanto-axoid, which only performs 
 one movement, viz., rotation. 
 
 Mechanism of the Occipito-atlantal Articulation. 
 The movements of flexion and extension of the head upon the atlas are very limited ; 
 when the head is decidedly bent or inclined, the effect is produced by motion of the 
 whole cervical region. It is possible to distinguish flexion at the occipito-atlantal artic- 
 ulation from that which is produced by the entire cervical region. In the first case, the 
 chin approaches the vertebral column, and the skin on the upper part of the neck is 
 
 * We should form an incorrect notion of the obstacle resulting from the lateral ridges on the bodies of tne 
 Tcrtebrse, in the pcrfiinnanre of rotation, if we were to study them only on the disarticulated skeleton. In the 
 recent subject they scarcely (ouch the vertebra above, on account of the intervertebral disc. 
 
124 ARTHROLOGY. '''''^' 
 
 wrinkled transversely ; in the latter, the spine bends at the same time as the head, con- 
 sequently the interval between it and the chin remains the same, and there are no trans- 
 verse viTinkles of the skin. 
 
 During flexion the condyles glide backward ; the odontoid, the occipito-axoid, and the 
 posterior ligaments are stretched, but in extension the gliding takes place in an oppo- 
 site direction. 
 
 The occipito-atlantal articulation is deprived of the power of rotation by the direction 
 of the condyles, which mutually obstruct this movement. In birds, which have only one 
 condyle, the articulation of the head admits of very extensive rotation. In the human 
 subject there is a slight movement of rotation at this joint, when the head is previously 
 ioclined upon one of the condyles, which then serves as a pivot. 
 
 Mechanism of the Atlanto-axoid Articulation. 
 
 In the movements of this articulation, we should regard the atlas and the head as 
 forming only one piece. There are no movements either of flexion or extension. The 
 inclusion of the odontoid process in the syndesmo-atlantal ring prevents even the slight- 
 est motion of the atlas, either forward or backward ; for in the forward motion, or flex- 
 ion, the atlas is fixed by the transverse ligament, which presses upon the odontoid pro- 
 cess ; and in the backward motion, or extension, the atlas is fixed by its own anterior 
 arch, which is brought in contact with the same obstacle. There is, moreover, no lat- 
 eral inclination at this joint, for this is prevented by the odontoid ligaments. Rotation 
 is, therefore, the only movement which remains. In this motion, in which the head de- 
 scribes the arc of a large circle upon the vertebral column, the syndesmo-atlantal ring 
 turns upon the axis as a wheel upon its axle. Of the two plane surfaces of this joint, 
 one glides forward, and the other backward ; one of the odontoid ligaments is stretched, 
 and the other relaxed. These ligaments, it should be observed, limit the extent of rota- 
 tion, which explains the necessity for their great strength ; but, great as this is, their 
 resistance is occasionally insufficient, and the odontoid process breaking one of them, 
 slips below the transverse ligament, and occasions death by compressing the spinal cord, 
 Luxation, therefore, of this articulation is to be dreaded, not merely for the same rea- 
 sons as other dislocations, but as being a cause of compression of the spinal marrow. 
 
 The entire movement by which the face is turned to either side should not be attrib- 
 uted to this articulation alone, for it extends to the fourth of a circle on each side, and 
 such a degree of motion would dislocate the articular surfaces of the atlas and the axis. 
 
 Articulations of the Cranium. 
 
 All the bones of the cranium are united together by synarthroses. We have here to 
 examine, as in all other articulations, 1. The articular surfaces ; 2. The means of union. 
 As the bones of the cranium form a complete cavity, closed in every direction, they unite 
 by their entire circumferences or by their edges ; and as the solidity of joints is in a di- 
 rect ratio to the extent of the articular surfaces, the bones of the cranium, which are 
 only in contact by their edges, would have been very slightly connected, had it not been 
 for the following provisions : 1. The cranial bones are generally thicker at the circum- 
 ference than in the centre ; 2. They are almost all provided with marginal denticulations 
 that multiply three or four fold the points of contact; 3. The edges, instead of being cut 
 perpendicularly, are bevelled so as to overlap each other, and thereby present much more 
 extensive corresponding surfaces ; 4. We should observe, also, the number of projecting 
 and retreating angles that are formed by these bones ; and, 5. The sinuous arrangement 
 of their edges, all of which arrangements are most favourable to the increase of solidity. 
 
 We should remark, however, that these different modes of ensuring solidity are not 
 employed indiscriminately over the whole scull. In the vault of the cranium, for exam- 
 ple, firmness is attained by the mutual adaptation of the serrated margins of the bones 
 at the upper and at the back parts, and by their overlapping at the sides ; in the base, on 
 the contrary, the sohdity chiefly depends upon the breadth of the contiguous surfaces, 
 and upon the reception of projecting into corresponding retreating angles. Examples of 
 this double arrangement may be seen in the articulation of the occipital and sphenoid 
 bones, which is accomplished by means of broad surfaces, and in the articulation of the 
 projecting angle formed by the petrous portion of the temporal bone with the retreating 
 angle formed by the occipital bone behind and the sphenoid in front. 
 
 This description will suffice to give a general idea of the mode of union between the 
 bones of the cranium. It would evidently exceed the limits of this work to dilate upon 
 the form of each of the sutures, and to follow Monro in distinguishing fourteen or fifteen 
 different kinds. Nevertheless, we do not think a few words regarding the principal 
 forms of the indentations will be out of place. We would therefore observe, that the 
 tooth-like projections are sometimes four or five lines in length, and are themselves in- 
 dented on their edges, secondary denticulations being thus formed. They are generally 
 straight, but are sometimes alternately bent towards the external and the internal sur- 
 face. Some of the teeth are, as it were, pediculated, and are enclosed between the others, 
 thus holding a middle place between the Wormian bones and the ordinarj' denticulations 
 
MECHANISM OF THE CRANIUM. 125 
 
 We should remark that the name suture, piopurly speaking, belongs more especially 
 to those sutures in which the bones are dovetailed ; that those sutures, the uniting sur- 
 faces of which are broad and oblique, are generally called squamous ; and that the sutu 
 ra harmonia are those in which the indentations are scarcely perceptible. We must 
 also observe, 1. With regard to the sutures, that their indentations are much deeper on 
 the external than on the internal surface of the bones of the cranium ; 2. With regard to 
 those sutures which are bevelled, that they often present alternate oblique sections, hav- 
 ing opposite directions, so that of two bones, the one that overlaps the other at one part 
 of the suture is, at another part, itself overlapped : of this we have an example in the 
 fronto-parietal suture. 
 
 Means of Union of the Bones of the Cranium. 
 We have remarked, in speaking of the development of the bones, that those which 
 are subsequently united by immovable articulations are formed in a piece of cartilage 
 that is common to them all. Portions of this cartilage, not yet encroached upon by os- 
 sification, serve as the uniting media. It is evident, therefore, that these cartilages of 
 the sutures are broader when the amount of ossification is less, viz., in the earher periods 
 of life. The pericranium, on tlie outside, and the dura mater, on the inside, although 
 they adhere more firmly to the bones along the lines of the sutures, cannot to any con- 
 siderable extent contribute to strengthen the union of the bones of the cranium. 
 
 Mechanism of the Cranium. 
 
 While the vertebral column performs four offices, 1. A cylinder or canal of protection ; 
 3. A column of support ; 3. The central lever of locomotion ; and, 4. An organ movable 
 on itself in its different parts, the cranium only performs two : 1. An organ of locomotion ; 
 2. An organ of protection. As an organ of locomotion we have already fully studied it, 
 when examining the movements of the vertebral column, and, consequently, it only re- 
 mains for us to examine its mechanism as protecting the nervous mass which it encloses. 
 
 The cranium is nothing more than a bony envelope added to the fibrous one which en- 
 closes the brain, and is exactly moulded, on its inner surface, to the external surface of 
 the organ it encloses. Before its complete ossification, the cranium may experience an 
 enlargement or diminution in size in proportion as the organ it contains is enlarged or 
 diminished in volume ; but so soon as its ossification has been completed, its capacity is 
 independent of the volume of the brain. If that organ is atrophied, the vacancy is fiUed 
 up by serous fluid ; if hypertrophied, a fatal pressure is the consequence. The state- 
 ments which have been made by some, that the capacity of the interior of the cranium 
 increases in men of genius, and that the head of Napoleon increased wonderfully in size 
 during the progress of his reign, we consider as mere vagaries of the imagination. As 
 the cranium encloses the brain, it is evident that any motion between the bones which 
 form this case would be attended with fatal consequences. They are, therefore, im- 
 movably articulated to each other. It might be supposed that this solidity could have 
 been better secured, had the brain-case been formed of one instead of a number of bones. 
 But, independently of the other important objects obtained by its being made up of a 
 number of separate pieces, its power to resist fractures is increased by this arrangement, 
 seeing that forces applied to it, in being transmitted through its different articulations, 
 are weakened, and operate much less violently than they would have done without this 
 arrangement. 
 
 What has been said above of the immobility of the bones of the cranium is not equally 
 true at all periods of life. During foetal existence, and the first few years after birth, the 
 intervals between the bones of the cranium are occupied by a flexible, cartilaginous sub- 
 stance, which permits those of the roof to move pretty extensively upon each other. 
 Since, therefore, the conditions of solidity are not the same at this period as in the adult, 
 we must examine the mechanism of the cranium both in the foetus and in the adult. 
 
 1. In the foetus, the conditions of solidity must be studied both in the roof and in the 
 base of the cranium. 
 
 In the roof of the cranium, the incomplete ossification allows the bones to move upon 
 each other, and in this respect the encephalon is imperfectly protected. But, on the 
 other hand, the presence of these cartilaginous intervals diminishes the momentum of a 
 violent force applied to the cranium, and thus prevents, in some degree, both fractures 
 of the cranium and concussions of the brain. The mobility of the bones is principally 
 displayed at birth, in their overlapping, when the head of the foetus is passing through 
 the pelvis. The base of the cranium is incompressible at the same period, and the bones 
 are immovable, because ossification has so far advanced that they are only separated by 
 very thin layers of cartilage. Tliis arrangement is well adapted for the protection of the 
 most important parts of the encephalon, which are in the vicinity of the base of the cranium. 
 
 2. In the adult, the roof and the base of the cranium form one piece. The roof being 
 most exposed to violence, we shall examine the mechanism of resistance in the cranium 
 to blows directed vertically upon the top of the head ; and it will be easy to apply what 
 is said in explanation of the effects of a force so directed, to cases in which violence is 
 applied in other directions. 
 
tm 
 
 ARTHROLOGY. 
 
 The effects which may be presumed to follow a violent blow on the top of the scull, 
 are, 1. Concussion of its bony parietes, succeeded by their elastic reaction ; 2. Disjunc- 
 tion of the pieces entering into the formation of the scull ; and, 3. Fracture of those 
 pieces. We shall examine the method in which these results may be produced. 
 
 1. Concussion and Compression of the Cranium without Fracture. — The cranium may be 
 looked upon as a hollow sphere, endowed with a certain degree of elasticity, depending 
 partly upon the osseous tissue itself, and partly upon the cartilaginous laminae which 
 separate the bones ; and it cannot, therefore, be doubted that, from pressure, or violent 
 blows on the top of the head, the scuU may undergo a flattening, and then recover its 
 original condition, like a hollow baU of ivory when struck vertically. The truth of this 
 explanation may be shown at once by projecting a scull against a resisting surface, when 
 it wiU be found to rebound like an elastic ball. However sUght this flattening may be, 
 and the recovery which follows it, the known laws of physics will not aUow us to deny 
 its possibility. 
 
 2. Tendency to Disjunction of the Bones of the Cranium. — This separation has never been 
 observed as the consequence of external blows. The following is the manner in which 
 displacement is prevented in cases of blows on the top of the head. It is evident that 
 violence applied in this direction would have a tendency to depress the upper edge of 
 the parietal bones ; but this cannot take place without forcing the lower edge outward ; 
 and as, from the peculiar formation of the squamous suture, the parietal bones are over- 
 lapped by the temporal and the sphenoid, this edge cannot be driven outward without 
 giving the temporal bones such a motion as will tighten the articulations of the base of 
 the cranium. All these articulations are remarkable in this respect, that the projecting 
 angles of some of the bones are received into the retiring angles of others. This is ex- 
 emplified in the articulation of the petrous portion of the temporal bone with the sphenoid 
 and the occipital bone, and in the basilar process of the occipital bone with the two tem- 
 porals and the sphenoid. The residt of all these arrangements is, that blows upon the 
 top of the head, instead of separating the bones of the cranium, tend to render their union 
 still closer. 
 
 3. Another effect of blows on the top of the head may be fracture of the cranial bones ; 
 and it will be impossible to comprehend the nature of many of these fractures, without 
 a knowledge of the following points of structure : 1 . The cranium is of unequal thickness 
 in different parts. This circumstance explains how a round body, striking the cranium 
 in a spot of sufficient strength to resist the impulse, may cause a fracture of a more or 
 less distant part, where the parietes are thinner, and consequently weaker. It may be 
 conceived that this kind of fracture may take place either in the bone struck, or in other 
 bones, and that it may affect the internal table only, the external remaining uninjured. 
 2. The cranium is so constructed, that a shock impressed upon the top is concentrated at 
 the base, being propagated on the sides to the temporal bones and their petrous portions, 
 as well as to the great wings of the sphenoid and the body of that bone ; behind, by the 
 occipital bone to the basilar process and the body of the sphenoid ; and in front, by the 
 fiontal bone and the roof of the orbits, to the smaller wings and body of the sphenoid. 
 It will thus be seen how blows upon various parts of the scull may concentrate their ef- 
 fects upon the base of the cranium ; and this explains the production of fractures at the 
 base, in consequence of violence inflicted on the roof of the scull. 3. Most of the cranial 
 bones are bent and angular. This disposition, which is observed at the union of the or- 
 bital and frontal portions of the frontal bone, and at the junction of the squamous and 
 petrous portions of the temporal bone, explains how these bones may be broken by the 
 transmission of shocks from the roof For we may conceive, when violence is applied 
 to a bone which is bent at an angle, that this angle will be the seat of a decomposition 
 of the force, one portion of which is transmitted to the part of the bone below the angle, 
 while the remaining portion acts against the angle itself in the original direction, and 
 may thus determine a fracture of that part of the bone. 
 
 Although the roof of the cranium is most exposed to injury, yet some parts of the base 
 may be reached by penetrating weapons, as the roof of the orbits and the cribriform plate 
 of the ethmoid. It should be remarked, also, that these are the thinnest parts of the scull. 
 
 Articulations of the Face. 
 
 The articulations of the face comprise those of the upper and of the lower jaw. 
 Articulations of the Bones of the Superior Maxilla with each other, and with the Cranium. 
 
 All these articulations are sutures, but they have not such large indentations as the 
 bones of the cranium ; almost all are united by harmonia or juxtaposition. At the same 
 time, it should be remarked that a true dovetailing exists in these articulations, as may 
 be seen in the junction of the superior maxillary bones (the fundamental articulation of 
 the face), which is effected by means of thick furrowed surfaces, mutually and firmly 
 adapted to each other. 
 
 No suture in the whole scull is stronger than that between the malar and the maxil- 
 lary bones ; indented sutures are most common on the sides of the face. The manner 
 
ARTICULATIONS OF THE FACE. 127 
 
 in which the vertical portion of the palate bone is received into the furrow in the open- 
 ing of the maxillary sinus, afFords an illustration of the suture by reception. There are 
 some well-marked indentations in the articulations of the bones of the face with those 
 of the cranium ; as in the articulation of the nasal bones ; of the ascending processes of 
 the superior maxillae ; and of the malar bones with the frontal ; in that of the sphenoid 
 with the malar bones ; and of the latter with the zygomatic processes of the temporal 
 bones. Simple juxtaposition is met with in the junction of the ethmoid with the roof of 
 the orbit ; of the palate bone with the pterygoid processes ; and of the vomer with the eth- 
 moid ; but there is a mutual reception in the articulation of the vomer with the sphenoid. 
 With regard to the means of union, in addition to the firm union resulting from the 
 configuration of the articular surfaces, there is also a thin layer of cartilage, continuous 
 with that which formed the matrix of the bones, and which is itself afterward obhterated 
 during the progress of ossification. 
 
 Mechanism of the Articulations of the Upper Jaw. 
 
 As the mechanism of the face is adapted both to resist force applied from below through 
 the medium of the lower jaw, and also the effects of external violence, it is necessary to 
 analyze the conditions of solidity resulting from the configuration of the upper jaw ; and 
 in order to appreciate these correctly, we must analyze the framework of the face. 
 
 The upper jaw, considered as a whole, forms inferiorly a sort of parabola, circumscri 
 bed by the alveolar border, which is the strongest part of the bone, and receives the di- 
 rect impulse of the lower jaw ; it curves backward, and forms the roof of the palate, 
 which gradually diminishes in thickness ; and, not receiving the impulse of the lower jaw 
 directly, its construction is not so solid as the alveolar border. The upper jaw becomes 
 broader and flattened above, and separates into different parts or prolongations, which, 
 after enclosing certain openings, unite with the cranium by means of several processes, 
 that form, as it were, so many columns for resisting any impulses transmitted from below. 
 
 These columns are, 1. The fronto-nasal, constituted on each side by the ascending pro- 
 cess of the superior maxillary bone. These columns, which correspond to the canine 
 teeth, are remarkably strong in carnivorous tribes ; and to their great size may be attrib- 
 uted the lateral position of the orbits in these animals. The interval between these 
 columns is occupied above by the nasal bones ; but an opening is left between them, be- 
 low, shaped like a heart on playing cards. The whole of that portion of the alveolar 
 edge situated beneath this opening is weaker ; but it should be remarked, that it corre- 
 sponds to the incisor teeth, which, being adapted for cutting, divide instead of bruising 
 or tearing the food, and are, consequently, not subject to such powerful efforts as the 
 canine and molar teeth. 
 
 2. The second pair of columns is formed by the malar eminences, which are contin- 
 uous with the alveolar border, by the vertical ridge separating the canine from the zygo- 
 matic fossa. These columns, which correspond to the second great molar teeth, may 
 be called the zygomato-jugal, because they are subdivided into two other secondary col- 
 umns, the vertical, malar, or jugal, and the horizontal or zygomatic. The jugal columns 
 are much stronger than the fronto-nasal, and are continuous with the external orbital 
 processes of the frontal bone, and with the anterior thick and indented edges of the 
 great wings of the sphenoid : the second, or horizontal, articulate with the zygomatic 
 processes of the temporal bones, and with them constitute the zygomatic arches. From 
 this arrangement, it may be understood how effectually the bevelling of the end of the 
 zygomatic process that rests upon the malar bone is adapted for resisting impulses com- 
 municated from below. The zygomatic arches, also, form props that oppose all trans- 
 verse displacements. The mode of. articulation of the zygomatic processes with the 
 malar bones is such, that the zygomatic arches, although horizontal, are well C8dculated 
 to resist any force from below. In carnivora, where there are no jugal columns, the 
 zygomatic arches are enormously large. 
 
 The fourth pair of columns are the pterygoid,, intended to support the face in the antero- 
 posterior direction, being articulated with the maxillary bones through the medium of 
 the palate bor.es ; these also oppose any displacement upward, and, moreover, serve to 
 support the back part of the alveolar border. 
 
 There are, therefore, four pairs of columns, vi»., Vae fronto-nasal, the jugal, the zygo- 
 matic arches, and the pterygoid columns. They are almost entirely composed of compact 
 tissue. The principal columns are situated immediately above the first great molares, 
 where the jugal, zygomatic, and pterygoid columns are concentred, and where the most 
 violent impulses are received. The fronto-nasal columns correspond to the canine teeth ; 
 their strength is proportioned to that of these teeth, and hence, in carnivorous animals, 
 the ascending processes of the superior maxillae are very large and thick. The fronto- 
 nasal and jugal columns are near each other below, and only leave a small space be- 
 tween them, which is occupied by the two small molares ; but they are separated to a 
 considerable distance above, and enclose the orbital fossae. 
 
 In this manner the deep fossae in the face are formed without being prejudicial to its 
 strength. Even the maxillary sinus does not much diminish the solidity of the face. 
 
128 ARTHROLOGY. 
 
 because it is situated in the interval between the columns, and because only a small 
 portion of it corresponds to the alveolar border. 
 
 These details wiU suffice to show that the upper jaw has been framed to resist ex- 
 ternal impulses, but especially forces communicated from below by the lower jaw ; that 
 the alveolar border, being intended to receive the impulse directly, is most strongly con- 
 structed ; that the whole force applied to the upper jaw is transmitted by the fronto-nasal 
 columns to the internal orbital processes, by the malar columns, partly to the external 
 orbital processes, and partly to tlie zygomatic arches, and by the palate bone to the ptery- 
 goid columns of the sphenaid ; that the vomer transmits little or nothing either to the 
 ethmoid or the sphenoid ; and that the cranium, on its part, opposes very imyielding 
 structures to the sustaining pillars of the face. To forces directed from before back- 
 ward, the zygomatic arches and the pterygoid processes offer great resistance ; against 
 lateral violence each malar bone resists like an arch, and transmits the impulse it has 
 received to the superior maxillary bone, the frontal and the sphenoid. \ The greatest 
 part of the impulses communicated to the face are then ultimately tranbtiitted to the 
 cranium ; and were it not for the multiplicity of its constituent parts, and the great num- 
 ber of articulations which absort) part of the force, the brain contained within it would 
 be frequently exposed to dangerous violence. The upper jaw is concerned in the pro- 
 cess of mastication merely as a means of support ; for though it may be raised when the 
 mouth is opened, and depressed when the mouth is shut, these movements belong to 
 the entire head, and result from the action of its extensor muscles, which thus become 
 powerful auxiliaries of mastication in the carnivorous animals. 
 
 Temporo-maxillary Articulation (figs. 65, 66, and 67). 
 This joint, the centre of all the movements of the lower jaw, is a double condyloid ar- 
 ticulation. The articular surfaces are, 1. The two condyles of the lower jaw, transverse- 
 ly oblong, and directed somewhat obliquely inward and backward, so that their axis, if 
 prolonged, would intersect behind : 2. The glenoid cavity of each temporal bone, and the 
 transverse root of its zygomatic process. These surfaces are covered with cartilage. 
 The glenoid cavity is remarkable both for its depth and its capacity. Its depth is in- 
 creased by several eminences on its borders : viz., on the inside, by the spine of the 
 sphenoid ; and behind, by the styloid and the vaginal processes, the latter of which is 
 nothing more than the anterior lamina of the auditory meatus. The capacity of the 
 glenoid cavity is no less remarkable, being double or triple that which would be neces- 
 sary to receive the condyle ; moreover, the whole of this cavity is not articular, the part 
 situated behind the glenoidal fissure being extraneous to the joint. This disproportion 
 between thp cavity and the condyle is only observed in man and in ruminantia : in ro- 
 dentia and carnivora, the one is exactly proportioned to the other. The portion of the 
 glenoid cavity posterior to the fissure affords an example of those supplementary cavities 
 that, in certain circumstances, increase or replace the principal cavity. All that part of 
 the glenoid cavity situated anteriorly to the fissure belongs to the joint, and is, there- 
 fore, covered with cartilage.* 
 
 The transverse root of the zygoma, convex from before backward, and concave trans- 
 versely, is also articular, and covered by a cartilage, which is a continuation of that lining 
 the glenoid cavity. This articulation presents the only example in the body of two con- 
 vex surfaces moving upon each other. 
 
 The means by which motion is facilitated and union maintained in this articulation 
 are an inter-articular cartilage, an external lateral ligament, and two synovial mem- 
 branes ; the internal lateral ligament of some authors, and the stylo-maxillary ligament, 
 do not belong to this joint. 
 
 1. Inter-articular Cartilage {a, fig. 65). — This cartilage is interposed between the artic- 
 Pig, 65. ular surfaces ; it is thick at the circumference, and some- 
 
 times perforated at the centre, and resembles a bi-con- 
 cave lens, with this peculiarity, that its upper surface 
 is alternately convex and concave, to correspond with 
 the glenoid cavity and the transverse root of the zygoma ; 
 while the lower surface is concave, and adapted to the 
 condyle. Its circumference is free, excepting on the out- 
 side, whfere it adheres to the external lateral ligament, 
 and on the inside, where it gives attachment to some 
 fibres of the external pterygoid muscle. This circum- 
 stance is of great importance in regard to the mechanism 
 of the joint. The existence of an inter-articular cartilage in a joint which is subjected 
 to such considerable pressure, and is so often put in motion, agrees with the general 
 law already pointed out. (Vide The Akticulations in general). 
 
 * The study of the condyle and the glenoid cavity is of very great importance in comparative anatomy ; for 
 by the characters which they present, we may easily recognise the head of one of the rodentia, carnivora, or 
 ruminantia. 1. In carnivora, the condyles are transversely oblong, the long axes of both being in the same 
 line ; they are received into very deep cavities. 2. In rodentia, on the contrary, the long ditinietiy of the con- 
 dyles is directed from before backward. 3. In ruminantia, the glenoid cavity is flat, as well as the head of 
 the condyle, while the transverse root of the zygoma is scarcely discernible. 
 
ARTICULATIONS OF THE FACE. 
 
 129 
 
 Fig. 66. 
 
 2. External Lateral Ligament (J, fig. 66). — This ligament extends from the tubercle sit- 
 uated at the junction of the two roots of the zygoma to 
 the outside of the neck of the condyle : it is directed 
 obliquely downward and backward, and forms a thick 
 band covering the whole of the outside of the articu- 
 lation : it is in contact with the skin externally, and in- 
 ternally with the two synovial capsules, and the inter- 
 articular cartilage. 
 
 Anatomists have described, under the name of the 
 internal lateral or spheno-maxillary ligament (c, fig. 67), 
 an aponeurotic band, which, neither as regards its po- 
 sition or its use, can be considered as properly belong- 
 ing to the joint ; it is extended from the spinous process of the sphenoid to the spine sit- 
 uated on the inside of the orifice of the inferior dent2il canal. It is a very thin band, 
 which covers the inferior dental vessels and nerves, and pig^ 67. 
 
 separates them from the pterygoid muscles. Since the band 
 just described has no effect in giving strength to the joint, 
 
 it may be wondered that there is only one ligament for the ^g^^ TMHilllBUmK 
 
 articulation ; but it should be observed that, as the lower ^* VrnWiillilfri 
 
 jaw is articulated in the same manner at both its extrem- 
 ities, the external lateral ligament of the one exactly per- 
 forms the functions of an internal lateral ligament to the 
 other. 
 
 The stylo-maxillary ligament (d, figs. 65, 66, and 67) ap- 
 pears to me to hold the same place as the preceding ; it is a fibrous band extending from 
 the styloid process to the angle of the inferior maxUla. It has no relation to the union of 
 the articular surfaces. Its use appears to be that of giving attachment to the stylo- 
 glossus muscle. Meckel calls it the stylo-mylo-hyoid ligament. 
 
 3. There are two synovial capsules in this joint, one on the upper and the other on 
 the lower surface of the inter-articular cartilage (see fig. 65). Sometimes they commu- 
 nicate by an opening in the cartilage ; the superior is looser than the inferior ; and thus 
 the articular cartilage is more closely united to the condyle of the lower jaw than to the 
 glenoid cavity. 
 
 These two synovial capsules are in contact on the outside with the external lateral 
 ligament, and elsewhere with a thin layer of fibrous tissue. 
 
 Mechanism of the Temporo-maxillary Articulation. 
 
 In considering the action of this joint, the lower maxilla may be regarded as a ham- 
 mer which strikes against the anvil represented by the upper jaw ; it is a double angu- 
 lar lever, the axis of its motion being represented by a horizontal line that would pass 
 through the middle of the rami. This articulation, which belongs to the class of condy- 
 loid joints, has been ranged among the angular ginglymi, on account of the great extent 
 of its movements in two opposite directions, during its elevation and its depression ; but 
 it differs from them in being so constructed as to admit of slight lateral movements. It 
 can also be moved forward and backward. 
 
 1. Depression. — In this movement each condyle rolls forward in its glenoid cavity, and 
 then passes upon the transverse root of the zygoma, with a sudden jerk, which may be 
 easily felt by placing the finger on the condyle while the mouth is being opened ; at the 
 same time the angle of the jaw is moved backward. The condyle carries with it the 
 inter-articular cartilage ; for the union of these two parts is of such a nature that, even 
 in dislocation of the jaw, they are never separated. This depends not only upon the 
 comparative tightness of the lower synovial capsule, but also on the mode of insertion 
 of the external pterygoid muscle, which, being attached both to the neck of the condyle 
 and the inter-articular cartilage, acts simultaneously upon them. The other parts of the 
 joint are affected in the following manner : During depression of the lower jaw, the ex- 
 ternal lateral ligament is stretched ; the upper synovial capsule is distended behind, but 
 readily yields on account of its laxity. The spheno-maxillary band, or internal lateral 
 ligament, which is inserted at an almost equal distance from the condyle, which is car- 
 ried forward, and from the angle of the jaw, which is carried backward, remains unal- 
 tered, being neither stretched ner relaxed. 
 
 When the depression is carried too far, either from the effect of a blow upon the bone, 
 or during a convulsive yawn, the condyle is dislocated into the zygomatic fossa;, tearing 
 the superior synovial capsule, and carrying with it the inter-articular cartilage.* Thi^ 
 mode of displacement is impossible in the infant ; for, from the obliquity of the ascend- 
 ing ramus of tlie jaw, the upper part of the condyle looks backward, and, in order to be 
 
 * This luxalion-would be much more common were it not for the inter-articular cartilage, which, by al- 
 ways iiiri.mpji. ying the condyle, presents a smooth surface, oTer which the latter may glide in returning^ into 
 
 R 
 
130 ARTHROLOGY. 
 
 luxated forward, would have to traverse a much larger space than it does even when 
 the mouth is opened to the greatest possible extent. 
 
 2. In elevation, the condyle rolls backward, upon the transverse process, into the gle- 
 noid cavity. The external lateral ligament is relaxed. The obstacles to too great an 
 elevation are, 1. The meeting of the dental arches. 2. The presence of the vaginal 
 process and the anterior wall of the auditory meatus ; and it is very probable that the 
 extensive movements of the jaw in the old subject, when the teeth are lost, are permit- 
 ted by the size of the glenoid cavities. Without that portion of the glenoid cavity which 
 is behind the fissure of Glasserus, the toothless alveolar edges of the aged could never 
 be brought in contact. 
 
 The forward motion is not, like the preceding, the motion of a lever in which the jaw 
 turns upon its axis ; it is a horizontal movement, in which the condyle is brought under 
 the transverse root of the zygoma. A preliminary and indispensable condition to this 
 movement is a slight depression of the whole of the lower maxilla. In this movement 
 all the ligaments are stretched ; if it were carried too far, the coronoid process would 
 strike against the bone in the zygomatic fossa, and this circumstance would prevent the 
 possibility of luxation of the condyle. 
 
 The backward motion requires no special remark. 
 
 The lateral movements differ from the preceding in the mechanism by which they are 
 effected. In the first place, the whole bone does not move from its place. One of the 
 condyles alone escapes from its socket, while the other remains in the glenoid cavity. 
 The bone, therefore, turns upon one of the condyles as on a pivot. 
 
 The external lateral ligament of that articulation in which the condyle moves is much 
 stretched. 
 
 The lateral motions would have been much more extensive had not the two condyles 
 mutually obstructed each other in all movements but that of depression, by reason of 
 their opposite directions. This may be shown by sawing a maxilla through the middle, 
 and moving each of the halves. Moreover, the styloid and vaginal processes, and the 
 spine of the sphenoid, prevent displacement inward. 
 
 Articulations of the Thorax. 
 
 The articulations of the thorax comprehend, 1. The costo-verteDral articulations ; 2. 
 The chondro-sternal ; 3. The articulations of the cartilages of the ribs with each other ; 
 4. The junction of the cartilages and the ribs. 
 
 The Costo-vcrtebral Articulations {figs. 58 to 60, and 68). 
 
 Preparation. — Saw the ribs across at their posterior angles. Remove with care the 
 pleura and the subjacent cellular tissue in front, and the muscles of the vertebral grooves 
 behind. After having studied the superficial ligaments, expose, 1. The costo-transverse 
 interosseous ligament by a horizontal section of the rib, and the transverse process to 
 which it is attached ; 2. The costo-vertebral interosseous ligament by a similar horizon- 
 tal section, including one vertebra and one rib, and passing above the angular part of the 
 joint. This last ligament may be also exposed by a vertical section of the rib and the 
 two vertebrae with which it is connected. The costo-vertebral articulations have some 
 characters which are common to them all, and others that are peculiar to a few. 
 
 General Characters of the Costo-vertebral Articulations. 
 
 Articular Surfaces. — In this joint, the head of the rib is applied to the angular surface 
 formed by the two half facettes (//, fig. 58) upon the sides of the bodies of the dorsal 
 vertebraj, so that each rib is articulated with two vertebrae {costo-vertebral articulation, 
 properly so called) ; and, in addition, the tubercle of the rib is applied to the facette {g,figs. 
 58, 60, and 68) on the fore part of the transverse process {costo-transverse articulation). 
 
 With regard to the costo-vertebral articulation, it is to be remarked, 1 . That it affords 
 an example of a projecting angular facette received into a retreating angular facette, 
 which has giver, rise to the mistaken notion that this joint is an angular ginglymus ; and, 
 2. That in each articulation the lower hcdf facette is twice as large as the upper. 
 
 The surfaces of the costo-transverse articulation are, a convex facette belonging to the 
 tubercle of the rib, and a concave one belonging to the tranverse process. Sabatier af- 
 firms that the articular surfaces of the transverse processes look forward and upward in 
 the upper vertebrae, and forward and downward in the lower, and directly forward in 
 those which occupy the middle of the column. This arrangement has been referred to 
 in explanation of the mechanism of the dilatation of the thorax, by depression of the low- 
 er, and elevation of the upper ribs ; but this explanation is unfounded. 
 
 In addition to the costo-vertebral and costo-tran verse articulations, the neck of the rib 
 {c,fig. 68), without being in immediate contact with the tranverse process, is, in some 
 degree, united with it by symphysis. 
 
 Means of Union. — These joints are examples both of symphysis and arthrodia. Some 
 of the ligaments are external to the articulation, the remainder are interosseous. 
 
 The ligaments external to the articulation are, the anterior costo-vertebral or stellate lig- 
 
ARTICULATIONS OF THE THORAX. 131 
 
 ament, the superior and the inferior ligsiments, the posterior costo-transverse, and the 
 superior costo-transverse. 
 
 1. The anterior costo-vertebral, or stellate ligament {I, fig. 58), arises from the two verte- 
 brae with which the rib is connected, and from the corresponding intervertebral substance. 
 From these points its fibres converge, and are inserted in front of the extremity of the rib. 
 
 2 and 3. Besides the stellate ligament there are two small ligamentous bundles, a su- 
 perior and an inferior, which extend from each of the vertebrae, concurring to form the 
 articulation, to the extremity of the rib. 
 
 4. The posterior costo-transverse ligament {m,fig. 59 : transverse ligament of Boyer, poste- 
 rior costo-transverse ligament of Bichat) is a fibrous band stretched from the apex of the 
 transverse process, in an oblique direction, to the non-articular portion of the tubercle of 
 the rib. 
 
 5. The superior costo-transverse ligament (n, figs. 58, 59 : costo-transverse of Boyer, infe- 
 rior costo-transverse of Bichat) consists of a band, which arises from the lower edge of 
 each transverse process, passes obhquely, and is inserted, not into the rib, which articu- 
 lates with that process, but into the upper edge of the neck of the rib below. At the 
 place of this insertion, we always find a crest or spine. This ligament is sometimes di- 
 vided into two or three bundles ; it forms the continuation of a thin aponeurosis, which 
 covers the external intercostal muscle, and completes the externjd wall of the opening 
 through which the posterior branches of the intercostal vessels and nerves are transmit- 
 ted. This ligament is interposed between the anterior and posterior branches of these 
 vessels and nerves. 
 
 The interosseous ligaments are two in number. 1. A costo-vertebral interosseous ; 2. 
 A costo-transverse interosseous. 
 
 1. The costo-vertebral interosseous ligamervt (o,fig. 58) is a small bundle of fibres, very 
 short and very thin, extending horizontally from the projecting angle on the head of the 
 rib to the retreating angle of the vertebral facette, where it is continuous with the inter- 
 vertebral substance. 
 
 2. The costo-transverse interosseous ligament (a, fig. 68) is formed by some ligamentous 
 bundles intermixed with reddish adipose tissue, which stretch jYg-. 68. 
 from the anterior surface of the transverse process to the pos- 
 terior surface of the neck of the rib. An idea of the strength 
 of this ligament may be formed by attempting to separate the 
 rib from the transverse process, after the anterior costo-ver- 
 tebral and the posterior costo-transverse ligaments have been 
 divided. 
 
 There are three synovial capsules in the articulations of the 
 ribs with the vertebrae : one between the tuberosity and the 
 transverse process, and two small ones for the two surfaces which are separated by the 
 costo-vertebral interosseous ligament. 
 
 Characters peculiar to certain Costo-vertebral Articulations. 
 
 The articulations of the first, eleventh, and twelfth ribs alone present peculiarities. 
 
 1. Costo-vertebral Articulation of the First Rib. — The rounded head of the first rib is re- 
 ceived into a cavity on the side of the body of the first dorsal vertebra ; the articulation 
 is, therefore, a species of enarthrosis ; there is neither a costo-vertebral interosseous lig- 
 ament, nor a superior costo-transverse ligament ; the synovial membrane is much looser 
 than in the corresponding articulations. 
 
 2. The costo-vertebral articulations of the eleventh and twelfth ribs present the same char- 
 acters as the preceding in this respect, that the articular cavity for the head of the bone 
 is situated upon one vertebra alone. The head of the rib is flattened, or very slightly 
 convex, and there is no interosseous costo-vertebral ligament. The superior costo-trans- 
 verse ligament is much broader and stronger than in the other articulations. As the 
 eleventh and twelfth ribs have no tuberosities, and the transverse processes of the cor- 
 responding vertebrse are but little developed,* it follows that there is no costo-transverse 
 articulation ; but yet there is a costo-transverse interosseous ligament. All these liga- 
 ments are much more loose than in the other articulations. 
 
 Tlie Chondro-sternal Articulations (Jig. 69). 
 
 There are §even in number on each side, formed by the internal angular end of the 
 cartilages, which are received into the angular cavities on the side of the sternum. The 
 means of union are, 1. A radiated or anterior chondro-sternal ligament {a, fig. 69), which is 
 tolerably strong : it crosses in the median line with the corresponding ligament of the 
 opposite side, and is blended both with the periosteum and the aponeurotic insertions of 
 the greater pectoral muscles, in the thick fibrous layer which covers the sternum ; 2. 
 Two small ligaments, a superior and an inferior ; 3. A radiated or posterior chondro-sternal 
 ligament, much weaker than the anterior. The existence of a synovial membrane is 
 
 * Sometimes, however, the transverse process of the eleventh dorsal vertebra is enlarged, and articulated 
 to the eleventh rib. 
 
132 ARTHEOLOGY. 
 
 merely inferred from analogy, for it cannot be demonstrated. {Vide Articulations in 
 
 GBNERAL.) 
 
 The first, second, sixth, and seventh chondro-stemal articulations present some pe- 
 culiarities. 1. The cartilage of the first rib is sometimes continuous with the sternum, 
 and is sometimes articulated like the cartilages of the other ribs. I found in one sub- 
 ject the first rib excessively movable, because its cartilage, instead of being continuous 
 with the sternum, had its upper edge applied to the side of that bone to which it was 
 united by ligaments, and was ultimately articulated by a narrow extremity immediately 
 above the second rib. 2. The second cartilage (ft) is much more angular at its inner ex- 
 tremity than any of the others ; it is received into the retreating angle formed by the 
 union of the first two pieces of the sternum. Sometimes there is an interosseous liga- 
 ment in this joint, running from the angle of the cartilage to the bottom of the cavity, 
 and there are then two synovial capsules : in other cases there is only one (c), but it is 
 always more marked than in the other joints. 3. The articulations of the sixth and sev- 
 enth cartilages, besides the anterior ligaments, have also a chondro-xiphoid ligament more 
 or less strong, which crosses with the ligament of the opposite side in front of the ensi- 
 form cartilage and the lower end of the sternum. Sometimes this ligament only exists 
 for the seventh cartilage ; it is intended not only to strengthen the chondro-stemal ar- 
 ticulations, but also to maintain the xiphoid appendix in its place. 
 
 The Chondro-costal Articulations. 
 
 The cartilages are immovably united to the ribs ; the anterior extremity of the rib is 
 hollowed to receive the external end of the cartilage : there is no ligament. The perios- 
 teum is the only bond of union between the costal cartilage and the rib, as in the articu- 
 lations of the cranial bones. 
 
 The Artiadations of the Costal Cartilages. 
 
 The first, second, third, fourth, and fifth costal cartilages do not articulate together, 
 unless the aponeurotic laminae, sometimes very strong, which form the continuation of 
 the external intercostal muscles, and occupy the whole length of the cartilages, be con- 
 sidered as uniting media. 
 
 The sixth, seventh, and eighth cartilages, frequently the fifth, and sometimes the ninth, 
 present true articulations. Some cartilaginous processes arise from the neighbouring 
 edges, and come in contact with each other : there are sometimes two articular facettes 
 between the sixth and the seventh cartilages. The means of union are some vertical 
 fibres united in bundles so as to form two ligaments, the one anterior and thicker, the 
 other posterior and thinner. There is a much more distinct synovial membrane than in 
 the chondro-stemal articulations. The seventh, eighth, and tenth cartilages have not 
 always articular facettes, but are simply united by vertical ligaments. 
 
 Mechanism of the Thorax. 
 As the thorax performs the double oflice of protecting the organs which it encloses, and 
 el assisting by its movements in the function of respiration, we must consider its mecha- 
 nism with reference to both these ends. 
 
 Mechanism of the Thorax for the Protection of the contained Organs. 
 
 1. The following is the mechanism by which the thorax is enabled to resist pressure 
 or violent blows directed from before backward. The sternum is supported by the four- 
 teen ribs, which, like buttresses, oppose their united strength to any causes of displace- 
 ment or fracture ; it is therefore very rare to find the sternum driven backward, and all 
 the ribs broken, however great the violence may have been. The elasticity of the car- 
 tilages and of the ribs, and the number of articulations which exist in the thorax, are all 
 circumstances most favourable to strength, because they diminish the intensity of exter- 
 nal blows by neutralizing a certain amount of impulse : yet I have met with one case in 
 which all the sternal ribs were broken by a fall, as completely as if the anterior wall of 
 the thorax had been divided for an anatomical preparation. I should remark, also, that 
 the flexibility of the ribs and their cartilages permits great depression of the sternum 
 without fracture ; and this explains the possibility of contusion, and even rapture of the 
 heart, lungs, or great vessels, without fracture of the bones of the thorax. The degree 
 of resistance of the anterior wall of the thorax may be also considerably varied by the 
 state of relaxation or contraction of the muscles, which should be considered as active 
 and contractile supports to the arch, of which the stemum forms the key-stone. 
 
 2. In the case of lateral pressure or blows, the thorax resists, like an arch, the vault 
 of which is represented by the convexity of the twelve ribs, and its pillars by the ster- 
 num in front and the vertebrae behind. External violence cannot act upon the whole 
 side of the chest at once, as it does upon the front, and therefore the ribs ofltr a more 
 partial resistance laterally, and are accordingly much more easily broken by direct blows 
 In this case, also, as in the former, when the elevator muscles of the ribs are in action, 
 the resistance is considerably increased ; and individuals have been then able to beai 
 
ARTICULATIONS OF THE RIBS. 133 
 
 giiorttious •WTei^ts, which would, in all probability, have fractured the ribs, had the raus> 
 cles been relaxed. 
 
 What has been said above of the manner in which the ribs withstand violence is not 
 however, applicable to the false ribs, which, having no fixed point on the stemui.l are 
 depressed into the abdominal cavity. 
 
 Mechanism of the Thorax with reference to Mobility. 
 
 The thorax is not equally movable throughout. The middle portion, which corresponds 
 to the heart, and which is formed by the sternum and vertebral column, has a very limit- 
 ed degree of mobility, vvhile the sides which correspond to the lungs are endowed with 
 the power of extensive motion. 
 
 The movements of the thorax consist of alternate dilatations and contractions, from 
 which its mechanism has been compared to that of a pair of bellows. They result from 
 the motions which take place at the costo-vertebral and chondro-sternal articulations, 
 and at the articulations of the cartilages with each other. We cannot explain the move- 
 ments of each rib, and of the entire thorcix, without first analyzing the motions at each 
 of the above joints. 
 
 Movements of the Costo-vertebral Articulations. 
 
 These articulations permit only very limited gliding motions. In these movements, 
 each rib represents a lever, which moves upon the fulcrum afforded by the vertebral col- 
 umn. It may describe the movements, 1. Of elevation; 2. Of depression ; 3. It may be 
 carried inward ; 4. It may be carried outward ; 5. It may perform a revolving motion 
 around the cord of the arc which it represents. These different movements, which are 
 very obscure in the immediate neighbourhood of the joint, are more evident the gieater 
 the distance is from the posterior end of the rib. The means of union between the ribs 
 and vertebrae are so strong, that luxation of the ribs is impossible ; and the causes which 
 would tend to produce it would break the neck of the rib. 
 
 Each rib is capable of performing all these motions ; but, as they vary in degree in the 
 different ribs, we must examine them comparatively in the series of costo-vertebral ar- 
 ticulations. The eleventh and the twelfth ribs possess the most extensive power of 
 motion. They owe this, 1. To the circumstance of their being scarcely at aU united to 
 the very small transverse processes ; 2. To the loose state of their ligaments ; and, 3. 
 To the almost perfect flatness of their articulated surfaces. The extent of their move- 
 ments inward and outward should also be noticed. We shall find these movements 
 but less pronounced, in the eighth, ninth, and tenth ribs, they scarcely exist in the first 
 seven ribs. 
 
 The shape of the head of the first rib is undoubtedly favourable to mobility, and has 
 suggested the idea that it is the most movable of all the ribs ; but the articulation of 
 its tubercle with the transverse process of the first dorsal vertebra, and the tightness 
 of its ligaments, suflSiciently explain why this opinion is erroneous. 
 
 The movements which take place in the second, third, fourth, filth, sixth, and seventh 
 costo-vertebral articulations do not differ sufficiently to require any special mention. 
 
 Movements of the Chondro-sternal Articulations. 
 
 In these articulations there is even less gUding than in the preceding. The anterior 
 extremity of the first rib, or, rather, of the cartilage which forms its continuation, is the 
 least movable of all ; more commonly, it is completely fixed on account of its continu- 
 ity with the sternum, a circumstance which neutralizes the favourable conditions for 
 mobility presented by its posterior extremity. The eleventh and twelfth ribs, whose 
 anterior extremities are connected only to soft parts, are the most movable. The mo- 
 bility of the ribs in front decreases from the lower to the upper part of the thorax ; to 
 this rule the second rib is an exception, chiefly on account of tlie two synovial mem- 
 branes at its chondro-sternal articulation, which permit of greater motion. This, how- 
 ever, is variable, depending as it does on the absence or presence of an articulation be- 
 tween the first and second bones of the sternum, and upon the more or less variable 
 mode in which these two pieces are articulated. 
 
 Movements of the Cartilages upon each other. 
 
 The movements of this kind are restricted to the sixth, seventh, eighth, ninth, and 
 tenth ribs, the cartilages of which alone are articulated to each other. They are simple, 
 gliding motions, and this gliding is proportionate to the looseness of the ligaments. 
 Hence it follows, that the ribs wliich I have just mentioned are always moved simul- 
 taneously as they gUde slightly upon each other ; whereas the superior ribs are inde- 
 pendent in their movements. This independence, however, is not as great as it might 
 appear at first sight, on account of the interosseous aponeuroses, the interosseous mus- 
 cles, and the superior transverso-costal ligament, which is very narrow above, and forms 
 below large and shining aponeurotic laminae. 
 
 It results, from the facts above stated, that the most movable ribs are the twelfth 
 and the eleventh, which may be moved upward and downward, and, at the same time, 
 
134 ARTHROLOGY. 
 
 enjoy, in the highest degree, the movements of projection inward and outward ; that 
 the first rib is the least movable of all ; that the superior ribs may be moved isolatedly ; 
 that the inferior ribs are moved all together. 
 
 Movements of the entire Rib. 
 
 Since we now know all the elements of which the movement of the ribs is composed, 
 we shall easily comprehend the play of each of those bones isolatedly, and the play of 
 the whole thorax. 
 
 The movements of the entire rib are composed, 1. Of those which take place at the 
 sternal and vertebral articulations ; and, 2. Of those which result from its own flexibility 
 and elasticity. We shall endeavour to reduce the subject to its most simple elements. 
 Let us suppose, then, that the ribs are straight, inflexible levers : from their oblique po- 
 sition in reference to the vertical axis of the spinal column, their elevation will increase 
 the width of the intercostal spaces ; for it is a law of physics, that lines which are ob- 
 lique with regard to another line, and parallel to each other, become farther separated 
 when they are placed perpendicularly to that line. Hence it follows, that the contact or 
 the overlapping of the ribs is impossible during the movement upward of these bones. A 
 second effect of the elevation of this oblique lever is the advancement of the anterior 
 extremity of the rib, which movement increases proportionately to the length of the le- 
 ver ; hence results an increase of the antero-posterior diameter of the thorax. But as 
 the ribs are curved levers, and not rectilinear, in assuming the horizontal position, their 
 concavity must come to be directed perpendicularly to the median plane formed by the 
 mediastinum. It may be shown, geometrically, that the concavity of an arc which falls 
 perpendicularly upon a plane, includes a greater space than when it falls obliquely. From 
 the elevation of the ribs results, therefore, an increase of the transverse diameter of the 
 thorax.* 
 
 The arcs of the ribs, however, have not all the same curvature : each rib has its own 
 peculiar perimeter, and it may be proved that the more curved the rib, the greater is the 
 projection outward which it forms when elevated. Lastly, as in some ribs the upper 
 border forms the segment of a smaller circle than the lower, the movement of projection 
 outward is proportionally greater in these than in the other ribs. This assertion may 
 be experimentally proved by imitating the movements of elevation and depression on 
 the second rib. I- The greater the disproportion between the curvature of the superior 
 and that of the inferior border, the more marked will be the projection gjitward. This 
 is the reason why the elevation of the second and third ribs, when they are bent at once, 
 both by their faces and their borders, produce such a remarkable increase of the thoracic 
 capacity. 
 
 If the ribs and their cartilages were inflexit)le levers, the movements of elevation 
 would be much restrained ; but, by a mechanism, of which we find no instance elsewhere, 
 the flexibility of these levers introduces into the problem a power which is most impor- 
 tant and very variable, so that their movements are much more marked than would arise 
 from the mobility of the articular surfaces. These movements cannot be determined by 
 calculation. Now this flexibility, whence results a movement of torsion in the rib, or 
 of rotation round an axis, represented by the cord of the arc which the rib forms, is in a 
 direct ratio to the length of the ribs and their cartilages, and the flexibility of either. 
 Indeed, the movements of the ribs are much more considerable in children and women 
 than in old men ; and the deficiency of mechanical power in regard to breathing, which 
 corresponds to the smallness of the power of locomotion in old men, explains the sever- 
 ity which characterizes asthma and all the diseases of the lungs at this age. 
 
 We shall now examine the movements of the thorax in genercil. 
 
 Movements of the Thorax in general. 
 
 The general movements of the thorax, which result from those partial motions we 
 have been engaged in considering, are, 1. A movement of dilatation, corresponding with 
 the act of inspiration ; 2. A movement of contraction, corresponding with that of expi- 
 ration. 
 
 1 . The dilatation of the thorax is caused by the elevation of the ribs. By this move- 
 ment, the anterior extremity of each rib is carried forward, and the antero-posterior di- 
 ameter of the thorax is thus increased ; the most eccentric portion of the rib is carried 
 outward, and the transverse diameter of the thorax is thereby augmented. There is a 
 sort of antagonism between the upper and lower part of the thorax, with regard to the 
 direction in which the increase of its capacity is effected : in the upper part the trans- 
 verse diameter is most augmented ; in the lower, the antero-posterior diameter. 
 
 The most movable point in the superior ribs is at the centre of the curvature ; the 
 most movable point of the inferior ribs is at the junction of the ribs and the cartilages 
 But the columns to which the extremities of the ribs are attached are not equ£iUy mo- 
 
 * BoreUi, t. ii., p. 177. 
 
 t From measurements taken by Haller, it appears that the second rib is the most elevated during inspira- 
 tion ; and if this may be doubted, it cannot be denied that its eccentric movement is greater than that of ant 
 »f the other ribs. 
 
ARTICULATIONS OF THE SHOULDER. 135 
 
 vable : if the posterior extremity is fixed, the anterior extremity may be moved from its 
 place. This circimistance does not oppose the transverse enlargement being produced 
 by the elevation of the arcs of the ribs, though it introduces a new condition into the 
 problem, to wit, the elevation of the anterior column or the sternum. So long as the 
 movement of elevation of the ribs is limited to the costo-vertebrcd articulations and a 
 slight flexibility of the ribs and their cartilages, the sternum scarcely participates in the 
 motion ; but when the elevation is carried beyond a certain point, when all the powers 
 of inspiration are in activity, when there is an integral movement of the thorax, which 
 has not been sufficiently distinguished from the partijd movement, then the sternum is 
 carried upward with the ribs, then the first two ribs, which we have represented as the 
 essential props of the sternum, are themselves elevated, and this elevation must be the 
 Scune as that of all the other ribs, and must, therefore, be proportionately more consider- 
 able. Does the sternum perform an angular motion during its elevation, as Haller ima- 
 gined 1 On placing the thorax between two parallel planes, and on executing a forci- 
 ble movement of inspiration, we feel at the inferior portion a pressure, which seems to 
 indicate, in this inferior portion, a movement of projection forward. The lever formed 
 by the inferior ribs being longer, it seems, indeed, as though there ought to be an angular 
 motion ; but it will be observed that there is no pression tending to diminish the curve 
 which is described by the ribs ; that therefore the two halves of the arc which the curves 
 represent do not recede from each other, and that the powers of elevation simply draw 
 all the anterior extremities of the ribs upward ; indeed, the sternum is simply elevated 
 near the cervic£d region, retaining; its primitive direction, as Borelli had previously well 
 pointed out ; considering the flexibility of the cartilages, the angular motion is almost 
 impossible. 
 
 The enlargement of the thorax is effected by the elevation of the ribs, and takes place 
 either transversely forward or backward. The enlargement of the thorax in a vertical 
 direction is produced by a totally different mechanism, the contraction of the diaphragm, 
 of which we shall speak hereafter. 
 
 2. Let us now speak of the contraction of the thortix. This contraction is effected by 
 the depression of the ribs. In the first stage, the contraction is passive, because it re- 
 sults from the elasticity of the cartilages, which, on account of the relaxing of the eleva- 
 tor muscles, cease to be maintained in a state of torsion, and therefore react and restore 
 the rib to its primitive position, so that the rib and cartilage, according to the ingenious 
 remark of Haller, are alternately the cause of their respective movements. It ought to 
 be remarked, that the movement of depression is much more limited than the movement 
 of elevation ; and I may justly regard the superior transverso-costal hgament as being 
 destined to impose particular limits to that depression, during which the intercostal 
 spaces are narrowed. We may regard as a powerful auxiliary of the depression and the 
 contraction of the thorax the movement of projection inward, especially in the last five 
 ribs, which are in certain respects depending upon each other. This movement of pro- 
 jection inward is opposed to the transverse dilatation or the movement of projection out- 
 ward, which takes place especially at the superior portion, as has been seen above, and 
 as is shown every day by the use of the corsets. Afterward we shall see that the great 
 inspiratory powers, or powers of elevation, occupy the superior portion of the thorax, as 
 the great expiratory powers occupy the inferior portion. To the integral elevation of 
 the thorax, in the most considerable degree of contraction, corresponds an integral de- 
 pression, and this depression of the ribs is directly produced by muscles which bear the 
 name of expiratory muscles. 
 
 ARTICULATIONS OF THE SUPERIOR OR THORACIC EXTREMITIES. 
 
 Articvlaiions of the Shoulder. — Scapulo-humeral, — ■Humero-cuhital. — Radio-cubital. — Radio- 
 carpal. — Of the Carpus and Metacarpus. — Of the Fingers. 
 
 Articulations of the Shoulder. 
 The two bones of the shoulder are articulated together ; the clavicle is also united 
 with the sternum and the first rib. There are, therefore, two orders of articulations : 1 
 The intrinsic articulations of the shoulder, viz., the acromio- and coraco-clavicular artic- 
 ulations ; 2. The extrinsic, or the sterno- and costo-clavicular. 
 
 The Acromio- and Coraco-clavicular Articulations. 
 
 The clavicle is articulated, 1. With the acromion by its external extremity, the acro- 
 mio-clavicular articulation ; 2. With the coracoid process by its lower surface, the coraco- 
 clavicular articulation. 
 
 Preparation. — Remove the skin, the cellular tissue, and the muscles which surround 
 the joints ; separate the acromion from the spine of the scapula ; remove, in succession, 
 the different layers of the superior acromio-clavicular ligament, so as to be able to judge 
 of its thickness. Make a vertical section of the acromio-clavicular articulation, so as to 
 be able to observe the thickness of the ligaments and articular cartilages. 
 
136 ARTHROLOGY. 
 
 Aeromio-clavicular Articulation {fig- 69). 
 
 Articular Surfaces. — ^The clavicle and the acromion process oppose to each other a 
 plane, elliptical surface, with its greatest diameter directed from before backward. The 
 articular surface of the clavicle looks somewhat obliquely downward and outward, the 
 acromial facette looks obliquely upward and inward. The extent of these surfaces va- 
 ries greatly in individued cases, dependant on the degree of exercise to which the joint 
 is subjected.* 
 
 Means of Union and Promsion for facilitating Motion. — These are, 1. An intcr-articidar 
 cartilage, first pointed out by Weitbrecht ; it is by no means constant, and, when it does 
 exist, occupies only the upper half of the articulation. 2. An orbicular fibrous capsule {d, 
 fig. 69), which is very thick above and behind, and very thin below. It is composed of 
 distinct bundles, which are much longer behind than in front, and are strengthened by 
 some fibres belonging to the aponeurosis of the trapezius muscle ; it is not only attached 
 to the upper edge of the articular surface, but also to some inequalities upon the upper 
 surface of the acromion. It is composed of several layers, the deepest being the shortest. 
 3. A synovial membrane, of a very simple construction, supported below by adipose tissue. 
 
 Coraco-clavicular Articulation {fig. 69). 
 There can be no doubt concerning the existence of an articulation, where two surfaces 
 are contiguous, and capable of a gliding motion on each other ; one of them, the coracoid, 
 
 being almost always covered with carti- 
 lage and a synovial membrane ; and the 
 other, the clavicular, presenting some- 
 times a considerable process for this ar- 
 ticulation. 
 
 The means of union are two ligaments, 
 or, rather, two distinct ligamentous bun- 
 dles, a posterior and an anterior : they 
 are called coraco-clavicular. 
 
 1. The posterior ligament, named also 
 the conoid or radiated (c, fig. 69), is trian- 
 gular, and directed vertically ; it com- 
 mences by a narrow extremity, at the 
 base of the coracoid process, and is inserted into a series of tubercles on the posterior 
 edge of the clavicle, near its outer extremity. 
 
 2. The anterior ligament (/) {trapezoid ligament of Boyer) arises from the internal edge 
 of the coracoid process, and from the whole extent of the rough projection on the base 
 of this process ; from this it proceeds very obliquely to the ridge on the lower surface, 
 near the external end of the clavicle. 
 
 The two coraco-clavicular ligaments are continuous, and can only be distinguished by 
 the direction of their fibres. 
 
 We might with propriety range among the means of union of this joint an aponeurotic 
 lamina, to which much importance has been attached in surgical anatomy, and which is 
 known by the name of the costo-clavicular aponeurosis, or costo-coracoid ligament. It 
 may be easily felt under the pectoralis major in emaciated individuals : it extends from 
 the inner edge of the coracoid process to the lower surface of the clavicle, and converts 
 the groove for the subclavius muscle into a canal. 
 
 Mechanism of the Acromio- and Coraco-clavicular Articulations. 
 The acromio- and coraco-clavicular articulations perform well-marked gliding move- 
 ments ; and, in addition, the scapula rotates forward and backward upon the clavicle to a 
 considerable extent. In order to have a correct idea of these motions and their mecha- 
 nism, it is necessary to procure a shoulder with the ligaments still attached, and to ro- 
 tate the scapula backward and forward. It will be then seen that the scapula turns round 
 an imaginary axis passing through its middle. The looseness of the posterior half of the 
 orbicular and of the coraco-clavicular ligaments permits this rotatory motion ; of the two 
 coraco-clavicular ligaments, one limits the rotation forward, while the other, which, as 
 we have observed, runs in an opposite direction, hmits the rotation backward. Although 
 these motions are pretty extensive, they never give rise to dislocation, which can only 
 be produced by falls on the top of the shoulder, the coraco-clavicular ligaments being 
 lacerated if the luxation be complete. Incomplete luxations may, however, take place 
 without laceration of these ligaments. 
 
 The Sterno-clavicular Articulation {fig. 69). 
 
 The articulation of the inner end of the clavicle is composed of the sterna-clavicular 
 and the costo-clavicular articulations. 
 
 Preparation. — Saw through the clavicles vertically at their middle, and also the first 
 ribs at corresponding points ; and meet these two sections by a horizontal division of the 
 
 * In indiyiduals who have excrciscil the upper extremities very much, these surfaces are uneven, and 
 unequally incrusted '"•th np^lv-fonned cartilage. 
 
ARTICULATIONS OF THE SHOULDER. 1^7 
 
 Sternum. In order to see the interior of the sterno-clavicular joint, open the fibrous cap- 
 sule along the edge of the sternum above, or, rather, make a horizontal cut, which will 
 divide it into two parts, an upper and an under. 
 
 In order to examine the costo-clavicular articulation, open the synovial membrane be- 
 hind. 
 
 The sterno-clavicular articulation belongs to those which are formed by rmitual reception. 
 
 Articular Surfaces. — The articular surface of the sternum is transversely oblong con- 
 cave in the same direction, and convex from before backward ; it looks obliquely upward 
 and outward, and is situated on the side of the notch on the upper part of the sternum. 
 
 1. The articular surface of the clavicle is oblong from before backward, slightly concave 
 in the same direction, and convex transversely. From the respective configuration of 
 these surfaces a mutual jointing results, and the short diameter of the one corresponds to 
 the long diameter of the other ; so that the end of the clavicle overlaps the surface of the 
 sternum in front and behind, and the surface of the sternum projects beyond that of the 
 clavicle on the inside and the outside.* 
 
 2. There is an inter-articular lamina of cartilage (i. Jig. 69) between the articular sur- 
 faces, which is moulded upon them, and is very tliick, especially at the edges. It is 
 sometimes perforated in the centre. + It is so closely united by its circumference to the 
 orbicular Hgament that it is impossible to separate them : it adheres below to the carti- 
 lage of the first rib, and above and behind to the clavicle. 
 
 Means of Union. — These are, 1. The orbicular ligament {I, fig. 69). This name may be 
 given to the fibrous capsule which surrounds the joint in all directions. The fibres which 
 compose it have been regarded as forming two distinct bundles, known by the name of 
 anterior and posterior ligaments ; but it is impossible to distinguish between them. Fi- 
 bres proceed from all parts of the circumference of the articular surface of the clavicle, 
 obliquely downward and inward, to the circumference of the articular surface of the ster- 
 num. The capsule is not of equal thickness throughout ; it is thinner, and somewhat 
 looser, in front than behind, which may partly account for the more frequent luxations 
 of the clavicle forward than backward. 
 
 2. The inter-clavicular ligament (wi, Jig. 69), consisting of a very distinct bundle stretch 
 ing horizontally above the fourchette of the sternum, from the upper part of the innei 
 end of one clavicle to the inner end of the other. This ligament, which is much nearer 
 the posterior than the anterior part of the joint, establishes a sort of continuity between 
 the clavicles. It is the only direct means of union between the two shoulders. 
 
 3. There are two synovial capsules in this joint. That which is between the sternum 
 and the inter-articular cartilage is more loose than that between the cartilage and the 
 clavicle. 
 
 The Costo-clavicular Articulation {Jig. 69). 
 The articulation between the clavicle and the cartilage of the first rib is an arthrodia. 
 It is formed between an articular surface, which almost always exists on the lower sur- 
 face of the clavicle, and a corresponding facette on the upper surface of the inner end 
 of the first rib, at its junction with the cartilage. There is, in this articulation, a syno- 
 vial membrane, which is loose, especially behind. There is only one ligament, the cos- 
 to-clavicular {g, Jig. 66), a thick, strong bundle of fibres, quite distinct from the tendon of 
 the subclavius muscle, which is placed in front of it. It is fixed to the inner part of the 
 first costal cartilage, and is directed very obliquely upward and outward, to be inserted 
 into the under surface of the clavicle, to the inner side of the articular facette. 
 
 Mechanism of the Sterno-clavicular Articulation. 
 
 This articulation is the movable centre of the motions of the shoulder and of the 
 whole upper extremity ; and hence the utility of an inter-articular cartilage, to obviate 
 tte effects of blows or pressure : hence, also, the wearing away of this cartilage, the de- 
 formity and wasting of the articular surfaces, the depression of the right sternal facette, 
 and, lastly, the difference in the size of the sternal extremities of the right and left 
 clavicles. 
 
 This articuation, like all those effected by mutual reception, admits of motions in 
 every direction : viz., upward, downward, forward, backward ; and of circumduction, 
 resulting from the preceding, but not of rotation. 
 
 1. Movement of Elevation. — In this the sternal facette of the clavicle glides downward 
 upon the corresponding surface of the sternum ; the inter-clavicular ligament is relaxed ; 
 the cartilage of the first rib comes in contact with the inner extremity of the clavicle, 
 limits the degree of elevation, and prevents displacement. 
 
 2. Movement of Depression. — In this the sternal end of the clavicle glides in the oppo 
 site direction ; the articular surfaces of the costo-clavicular articulation press strongly 
 
 * Bichat considers that this arrangement of the articular surfaces predisposes to luxation ; it appears to ma 
 to have a precisely opposite effect, as it permits tho surfaces to move upon each other to a considerable extent 
 without being separated. i,- i, i, 
 
 t In a great number of cases this ligament is found partially wasted by the continued pressure to which the 
 joint is subjected. 
 
 s 
 
138 
 
 ARTHBOLOGY. 
 
 against each other, and limit the extent of this movement. It should be remarked, that 
 in this movement the subclavian artery is compressed betvi^een the clavicle and the first 
 rib, sometimes so completely as to arrest the circulation in the limb. 
 
 3. In the movement of the shoulder backward, the inner end of the clavicle glides for- 
 ward upon the surface of the sternum ; the anterior part of the orbicular capsule is 
 stretched ; and if the movement is carried beyond a certain point, the capsule is torn, 
 and the clavicle dislocated forward. 
 
 4. In the foricard movement of the shoulder, the inner end of the clavicle glides back- 
 ward. The anterior part of the orbicular ligament is relaxed, and the posterior part 
 stretched ; as, also, the inter-clavicular ligament, which, as we have seen, is nearer the 
 back than the front of the joint. In this motion luxation may take place backward. It 
 may be remarked that, of all the movements of the shoulder, the one described, in which 
 the clavicle is likely to be dislocated backward, is the most uncommon. 
 
 The movement of circumduction is more extensive forward and upward than backward. 
 The motions at the sterno-clavicular articulation are very circumscribed in themselves , 
 but when transmitted by the lever of the clavicle, they become very considerable at the 
 apex of the shoulder. 
 
 Mechanism of the Costo-clavicular Articulation. 
 
 This articulation, which may be regarded as a dependance of the sterno-clavicular, 
 admits of very limited motions, subordinate to those of the joint last described. 
 
 The Scapulo-humeeal Articulation {figs. 69 and 70). 
 Preparation. — Separate the upper extremity from the trunk, either by disarticulating 
 the clavicle at its sternal end, or by dividing it through the middle ; 2. Detach the del- 
 toid from its origin ; 3. Detach the supra and infra spinati muscles, the teres minor and 
 subscapularis, proceeding from the scapula to the humerus ; 4. Observe the adhesion of 
 the tendons of these muscles to the capsular ligament ; 5. Divide the capsule trans- 
 versely, after having studied its external aspect. 
 
 The scapulo-humeral articulation belongs to the class of enarthroses. 
 Articular Surfaces. — These are the glenoid cavity of the scapula, slightly concave, of 
 an oval form, with the large end downward, and looking directly outward ; and the head 
 of the humerus, consisting of about a third of a sphere, and presenting a surface three or 
 four times more extensive than the glenoid cavity. The axis of the head of the hume- 
 rus forms a very obtuse angle with that of the shaft of the bone.* 
 
 These two surfaces are covered by a layer of cartilage, which, on the head of the hu- 
 merus, is thicker at the centre than at the circumference ; while the reverse obtains in 
 the glenoid cavity. 
 
 Glenoid Ligament (a, fig. 70). — This is a fibrous circle, which surrounds the margin of 
 Fig. 70. the glenoid cavity, and appears to be formed by the bifur- 
 
 cation of the tendon of the long head of the biceps ; but it 
 is also partly composed of fibres proper to itself, which 
 stretch along the margin, arising from one point and ter- 
 minating in another. Notwithstanding this addition, the 
 head of the humerus is still too large to be received into 
 the cavity, so that a portion of it is always in contact with 
 the capsular ligament ; an inconvenience that is obviated, 
 in some measure, by the existence of a supplementary 
 cavity, as we shall presently see. The scapulo-humeral ar- 
 ticulation is therefore one formed by juxtaposition, and not 
 by reception ; from which arrangement it has lately been 
 classed among the arthrodial articulations. 
 
 Means of Union. — Like all enarthroses, there is here a fibrous capsule, or capsular lig- 
 ament (r, figs. 69 and 70), a sac with two openings, which extends from the margin of 
 the glenoid cavity to the anatomical neck of the humerus, t This capsule is remarkable 
 for its laxity. In fact, it is so capacious that it could lodge a head twice as large as that 
 of the humerus, and is so long that it will allow the articular surfaces to be separated 
 for more than an inch ; the only example of so great a separation without laceration of 
 the ligament.t 
 
 There is this peculiarity in the fibrous capsule of the shoulder-joint, that it is incom- 
 plete in one part, its place being there supplied by the tendons of the surrounding mus- 
 cles. In no joints, in fact, have the muscles and tendons more effect in strengthening 
 the articulation : they are, in a manner, identified with it. There are a great many varie- 
 .ies in this respect. The fibrous capsule is so much stronger, as it is less adherent to the 
 
 * Such is the shortness of the neck of the humerus, that its head, which looks upward and inward, would 
 6e almost entirely included between the prolonged planes of the body of the humerus. 
 
 t It should be remarked, however, that the fibrous capsule does not terminate directly at the anatomical 
 neck of the humerus, but is prolonged a little downward, and becomes blended with the insertions of the ten- 
 dons of the supra and infra spinati and subscapularis. 
 
 i In paralysis of the deltoid, the head of the humerus is so far separated from the glenoid cavity thai two 
 fingers may be inserted betweeu the articular surfaces. 
 
AKTICULATtONS OF THE SHOULDER. 189 
 
 surrounding tendons. The following are the relations of the capsule : 1. Below, in the 
 variable space between the subscapularis and teres minor, it corresponds to the cellular 
 tissue of the axilla, or, rather, to the thin edges of the muscles just mentioned : the head 
 of the humerus may, therefore, be easily felt by the fingers introduced deeply into the 
 axilla. 2. Above and on the outside, it is in contact with the tendon of the supra-spi- 
 natus, from which it is difficult to separate it, and is also in relation, though not immedi- 
 ately, with the arch formed by the acromion and clavicle with the deltoid muscle. 3. In 
 front, it corresponds to the subscapular muscle, from which it may be easily separated. 
 4. Behind, it corresponds to the tendons of the supra and infra spinatus, which are more 
 or less adherent to it, and the teres minor, which does not adhere to it. As to its struc- 
 ture, it is composed of fibres stretched irregularly from the neck of the humerus to the 
 circumference of the glenoid cavity. Its thickness is not great, nor is it equal through- 
 out, being most considerable below and in front ; but the capsule is strengthened above 
 by a considerable bundle of fibres (s, fig. 69), called the coracoid ligament, coraco-humeral 
 ligament, or accessory ligament of the fibrous capsule, which arises from the anterior edge 
 of the coracoid process, and spreads out on the capsule. This capsule always presents 
 an opening or an interruption above and before,* on a level with the superior border of 
 the subscapularis, which covers the opening in part ; or, rather, between this border 
 and the coracoid process. This opening is of an oval form ; its greatest diameter is 
 horizontal ; its large extremity is turned outward, and its small extremity inward. The 
 circumference of this opening, which is large enough to admit the point of the index fin- , 
 ger, is perfectly smooth, thick, and looks like mother-of-pearl, especially in its inferior 
 half. This opening is traversed by a considerable prolongation of the synovial mem- 
 brane, which reaches the basis of the coracoid process, and then extends between the 
 tendon of the subscapularis and the cavity which bears the same name. This cone- 
 shaped prolongation is variable with respect to its extent, and appears to have no other 
 object except to facilitate the gliding of the tendon of the subscapularis under the cora- 
 coid arch and against the border of the glenoid cavity. By distending the articular cap- 
 sule in several subjects, Mr. Bonamy has demonstrated this disposition to my perfect 
 satisfaction. I have been able to see that the synovial prolongation is sometimes divi- 
 ded into several cells by incomplete walls, by which this distended prolongation acquires 
 a crimpled aspect. Sometimes several of these cells are totally distinct from the syno- 
 vial membrane. 
 
 Inter-articular Ligament. — This name may, with propriety, be applied to the tendon (t, 
 fig. 70) of the long head of the biceps, which, arising from the upper part of the glenoid 
 cavity, turns like a cord over the head of the humerus, and passes along the bicipital 
 groove. It acts by keeping the head of the humerus applied to the glenoid cavity, and 
 forms a sort of arch that supports the bone when it is forced upward. In two subjects, 
 I found this tendon terminating by a strong adhesion in the bicipital groove, and thus 
 justifying the name of inter-articular ligament, which I have applied to it : the tendon 
 for the long head of the biceps took its origin from the same groove. I consider this 
 division of the tendon to have been accidental, for the bicipital groove was depressed, 
 and the inter-articular ligament flattened, and, as it were, lacerated. 
 
 The synovial capsule is the simplest of all in regard to its disposition. It lines the 
 fibrous capsule and the tendons which replace it, and is reflected, on one side, on the 
 neck of the humerus, and, on the other, upon the border of the glenoid cavity, to be lost 
 upon the circumference of the articular cartilages. It is remarkable, inasmuch as, 1. It 
 forms a fold round the tendon of the biceps, which is prolonged into the bicipital groove, 
 and terminates below by a cul-de-sac or circular fold, which prevents the effusion of the 
 synovia ; 2. It is open in one or two points,+ and presents two prolongations communi- 
 cating with the synovial bursse of the subscapularis and infra-spinatus. 
 
 Supplementary Cavity. — ^We may regard as a dependance of the scapulo-humeral artic- 
 ulation the vaulted arch formed by the coracoid and acromion processes, and the liga- 
 ment which unites them. In shape it corresponds to the head of the humerus, and is so 
 constructed that the coracoid process prevents displacement inward ; the acromion pre- 
 vents it upward and outward ; and the ligament between them opposes dislocation di- 
 rectly upward. This provision evidently compensates for the incomplete reception of 
 the head of the humerus in the glenoid cavity. A circumstance which proves the use 
 fulness of this vault, and the frequent contacts which it must have with the humerus, is 
 the presence of a synovial capsule, situated between the coraco-acromion vault on one 
 
 * I have seen this opening divided into two unequal portions by a fibrous bundle, strong, looking like mother- 
 of-pearl, and resemliling a little tendon. Often 1 have met a second interruption of the fibrous capsule on a 
 level with the concave border of the acromion process, which concave border acts as a real retum-puHey for 
 the infra-spinatus muscle, and is analogous to the return-pulley presented by the basis of the coracoid process 
 to the subscapularis muscle. When the capsule is perforated at this point, the synovial membrane gives oflf a 
 prolongation, which serves as a gliding capsule for the tendon of the infra-spinatus. 
 
 t [Although the synovial capsule of the shoulder-joint is thus occasionally prolonged into the bursoe mucosal 
 connected with the tendons of these muscles, it must not, therefore, be supposed that it is an exception to the 
 general rule that membranes of this nature always form shut sacs ; in such cases, the three structures consti- 
 tute one coiitiiiuuus cavity.] 
 
140 - " • . ARTHROLOGY. 
 
 side, and, on the other, the tendon of the infra-spinatus and the great trochanter of the 
 humerus. The study of the coraco-acromion vault cannot, therefore, be separated from 
 the study of the scapulo-humeral articulation, either under an anatomical and physiolo- 
 gical or surgical point of view. 
 
 The Coraco-acromial Ligament. 
 This ligament (m, figs. 69 and 70) forms part of the vault we have described : it is a 
 triangular bundle of radiating fibres, which extends from the apex of the acromion to the 
 A^hole length of the posterior edge of the coracoid process. Its external edge becomes 
 Ainner, and is continued into an aponeurotic lamina below the deltoid muscle, and sep- 
 arating that muscle from the joint. Its anterior and its posterior bundles are very thick, 
 folded upon each other, and look like mother-of-pearl ; its middle bundles are much less 
 thick. It is lined below by a synovial membrane, and is separated from the clavicle by 
 fatty tissue.* 
 
 Mechanism of the Scapulo-humeral Articulation. 
 
 The scapulo-humeral articulation admits of the most extensive movements of any 
 joint in the body : it is capable of every kind of motion, viz., forward and backward, and 
 also those of adduction, abduction, circumduction, and rotation. 
 
 Forward and Backward Motions. — In these the head of the humerus rolls upon the gle- 
 noid cavity, and moves round the axis of the neck of the humerus, while the lower extrem- 
 ity of the bone describes the arc of a circle, of which the centre is at the joint, the radius 
 being represented by the humerus.! The forward movement is very extensive, and may 
 be carried so far that the humerus may take a vertical direction exactly opposite to the 
 natural one. The motion backward is produced by the same mechanism ; the head of 
 the humerus turns upon its axis. This movement is limited by the contact of the head 
 of the humerus with the coracoid process, without which dislocation forward would be 
 very easily produced. It should be remarked that, in any considerable movement of the 
 humerus forward, the scapula is also moved, performing that sort of rotation which we 
 spoke of when considering the mechanism of the shoulder. And this combination of the 
 movement forward of the arm and the movement of rotation of the shoulder renders 
 every kind of displacement extremely difficult in exercising the movements of the arm 
 forward. 
 
 The movement outward, or abduction, is the most remarkable. It belongs exclusively 
 to animals possessed of a clavicle. In it the head of the humerus does not turn upon an 
 axis ; it glides downward upon the glenoid cavity, and presses upon the lower part of 
 the capsule. The shape of the glenoid cavity, which has its long diameter vertical, and 
 its broad part below, is advantageous as regards this motion. When abduction is car- 
 ried so far that the humerus forms a right angle with the axis of the trunk, a great part 
 of the head of the bone is below the glenoid cavity. If, while in this condition, the arm 
 be moved forward or backward, the great tuberosity of the humerus rubs against the 
 coraco-acromial arch, and forms with it a sort of supplementary articulation, lubricated 
 by the bursa situated between the coraco-acromion vault and this great trochanter.^ 
 The movement of abduction may be carried so far as to allow the arm to touch the head 
 without dislocation ; for the capsular ligament is sufficiently loose, especially below, to 
 receive almost the whole head of the bone without being torn. It should be remarked, 
 that during abduction the scapula is fixed, which explains the frequency of luxations of 
 the humerus downward. 
 
 Adduction is limited by the arm meeting with the thorax. When it is combined with 
 the forward motion, the upper and back part of the capsule, and the muscles which cover 
 it, are considerably stretched. The scapula does not participate in this movement, du- 
 ring which luxation can be occasioned only by a very strong impulse on the arm upward 
 and backward. 
 
 Circumduction is nothing more than the transition of the humerus from one to another 
 of these motions. The cone which it describes is much more extensive in front than 
 behind, a circumstance tending greatly to facilitate the prehension of external objects, 
 which is the chief purpose of the upper extremities. This predominance of the forward 
 motions has been already noticed in the sterno-clavicular articulation, and will be found 
 also in many others. 
 
 * [This is the ligamentum proprium anterius of authors ; but the author has taken no notice of another liga- 
 ment proper to the scapula, viz., the ligamentvm proprium posterius, a thin band of fibres stretched across the 
 notch at the base of the coracoid process, which it thus converts into a foramen. The supra-scapular nerve 
 generally passes below, and the artery above it.] 
 
 t It is through this ingenious and simple mechanism, of which we shall soon see another example in the 
 articulation of the femur with the os innominatnm, that the movement forward of the humerus maybe carried 
 far enough to describe a demi-circle, without the bone being displaced. 
 
 X If theory has led us to believe that the coraco-acromion vault contributed to luxation, by offering a point 
 of support to the lever represented by the humerus abducted from the body, a more careful observation, on the 
 contrary, has demonstrated that this supporting of the humerus was impossible, as the anterior border of the 
 coraco-acromion ligament is alone pressing against the humerus in the forcible abduction, and luxation is al- 
 ways produced in a middle abduction of the urni. 
 
ARTICULATIONS OF THE ELBOW. 
 
 141 
 
 Fig.n. 
 
 Fig. 72. 
 
 Rotation. — In this movement the humerus does not turn upon its own, but upon an 
 imaginary axis, directed from the head of the humerus to the epi-trochlea, parallel to the 
 bone. The manner in which the rotatory muscles embrace the head of the humerus is 
 highly favourable to this motion, by compensating for the shortness of the neck, which 
 serves as a lever for the rotatory movements. 
 
 The Humero-cubital Articulation, or Elbow-joint {figs. 71 and 72). 
 
 Preparation. — 1. Remove carefully the brachialis anticus muscle ; 2. Detach the ten- 
 don of the triceps from above downward, without opening the synovial capsule ; 3. Re- 
 move the muscles which are attached to the internal and external tuberosities, keeping 
 in mind that the lateral ligaments are intimately connected with the tendons of these 
 muscles. This articulation belongs to the class of trochlear joints (angular ginglymi). 
 
 Articular Surfaces. — On the humerus we find, 1. An almost perfect trochlea or puUey 
 presenting two edges, of which the internal is the more 
 prominent, so that, when the end of the bone rests upon 
 a horizontal plane, its shaft is directed very obliquely 
 from above downward and inward ; 2. The small head, 
 or articidar condyle, separated from the trochlea by a 
 furrow, which is also articular ; 3. Two cavities, a pos- 
 terior, which is very deep, and is intended to receive 
 the olecranon process, and an anterior, which is shal- 
 lower, and receives the coronoid. 
 
 The articular surfaces of the forearm are, 1. The 
 greater sigmoid cavity of the ulna, which exactly em- 
 braces the trochlea ;* 2. The glenoid cavity of the ra- 
 dius, which receives the small head of the humerus. 
 
 The means of union consist of four ligaments, two 
 lateral, an anterior, and a posterior. 1. The external 
 lateral ligament (a, Jigs. 71, 72) is blended with the ten- 
 don of the supinator brevis ; it is of a triangular form, 
 and stretches from the external tuberosity of the hu- 
 merus to the annular ligament, with which it becomes 
 continuous, and which seems to be in part formed by 
 it. Some fibres of this ligament are also inserted into 
 the outer part of the sigmoid cavity of the ulna. This 
 connexion of the lateral with the annular ligament is 
 of great importance with reference to the production 
 of luxations of the upper end of the radius, t 
 
 2. The internal lateral ligaments are two in number ; 
 one internal, properly so called, or humero-cormioidian ; 
 the other internal and posterior, humero-olecranian. 
 
 The former, or humero-coronoidian, which is partly 
 confounded with the aponeurotic tendon of the superficial flexor muscle of the fingers, 
 is a thick, rounded bundle, which arises below the internal tuberosity of the humerus, 
 and is inserted into the whole internal side of the coracoid process, and more especially 
 in its tubercle. 
 
 The second, or humero-olecranian, which might be described as a posterior ligament 
 of the articulation, is thin and radiating ; it arises from the posterior portion of the epi- 
 trochlea, and irradiates to be inserted into the whole extent of the internal border of the 
 olecranon ; the inferior bundles are the strongest, and come in part from the humero- 
 coronoidian ligament. The superior bundles are thin and slender, and reach beyond the 
 olecranon, in order to expand over the synovial membrane. 
 
 3. The anterior ligament (c) is a very thin layer, in which, however, three orders of 
 fibres can be recognised. The first, directed vertically, fonn a bundle which extends 
 from the upper part of the coronoid cavity to the lower part of the coronoid process ; the 
 second are transverse, and intersect the first at right angles ; and, lastly, the third are 
 obliquely directed downward and outward to the annular ligament, t We shall see, 
 hereafter, that the brachialis anticus renders an anterior resisting ligament entirely use- 
 less ; moreover, the most inferior and deepest fibres of this muscle are directly inserted 
 in this anterior hgament. 
 
 * Tbere is here, indeed, a hinge : it is the most remarkable example of a hin?e in the system ; it is the 
 most perfect angular ginglymoid. The two articular surfaces present a sinuous surface, wliich is alternately 
 concave and convex, a sort of catching which is seen nowhere else. 
 
 t These relations between the annular ligament and the external lateral ligament are so intimate that these 
 two ligaments are seldom torn independently of each other ; hence the consecutive dislocation "f the radius 
 .pon the cubitus in the luxations of the elbow ; hence, also, the luxations of the radius upon the humerus, 
 the ulna remaining in its place. (See an example of the luxation backward of the radius upon the humerus, 
 the ulna remaining in its place, Anat. Pathol., with plates, 8th number.) 
 
 t It should be remarked, that none of these ligaments of the elbow-joint are attached directly to the radius, 
 but that the fibres which are- directed towards this bone join the annular ligament. This arrangement allows 
 the radius to rotate with perfect freedom within its ring, which would have been impossible had the fibr>^ 
 been directly inserted into the bone. 
 
142 ARTHROLOGY. 
 
 4. The posterior ligament {d,fig. 72). The place of the posterior Hgament is occupied 
 by the olecranon and the tendon of the triceps. There are some fibres, however, which 
 sxtend from the external to the internal tuberosity of the humerus, which are in relation 
 with the synovial membrane in front, and the tendon of the triceps behind. The princi- 
 pal posterior ligamentous fibres are those which seem to arise from the humero-olecra- 
 nian hgament. 
 
 The synovial membrane covers the posterior surface of the anterior ligament ; from 
 this it is reflected upon the coronoid cavity, covers the olecranon cavity behind, and is 
 prolonged a little between the tendon of the triceps and the back of the humerus. In 
 this place it is widest and most loose. Below, it forms a prolongation, which extends 
 into the radio-cubital articulation, covering the whole inner surface of the annular liga- 
 ment, and forming a circular cul-de-sac below it, which prevents the effusion of the sy- 
 novia.* There is some synovial adipose tissue round the points of reflection, and also 
 at the margin of the coronoid and olecranon cavities. 
 
 Mechanism of the Humero-cuhital Articulation. 
 Extension and flexion, the only motions performed by this joint, are executed by it with 
 remarkable precision and rapidity. The precision of these movements depends, 1 . Upon 
 the exact fitting of the articular surfaces ; 2. Upon the great extent of the transverse di- 
 ameter, round which the movements of flexion and extension are performed as round an 
 axis ; 3. Upon the shortness of the antero-posterior diameter of the inferior extremity of 
 the humerus, and, consequently, on the smallness of the circle to which the curve of the 
 humeral trochlea belongs. 
 
 1. Flexion. — In this motion, which is very extensive, the radius and ulna move as a sin- 
 gle bone from behind forward, on the small head and trochlea of the humerus. It should 
 be observed that, in this movement, the obliquity of the trochlea from behind forward, and 
 from without inward, throws the forearm, when bent, in front of the thorax, and the hand 
 in front of the mouth. This motion is limited by the meeting of the coronoid process 
 with the coronoid cavity. When this motion is carried to the greatest extent, the upper 
 end of the olecranon descends to the level of the lowest part of the trochlea, and is, con- 
 sequently, below the line which passes through the two tuberosities, or condyles, of the 
 humerus. In this motion, the back part of the trochlea and the olecranal fossa are cov- 
 ered only by the tendon of the triceps, so that instruments can readily enter the joint at 
 this place. The flexion of the elbow, which constitutes a fundamental movement in pre- 
 hension of bodies, may be carried as far as possible, even so far as to cause the forearm 
 to meet the arm, without any risk of luxation, as any sort of dislocation here is impossi 
 ble, however extensive this movement may be. 
 
 2. Extension. — In this movement, the radius and ulna roll backward upon the humerus. 
 This motion can only be carried so far that the forearm and the arm form a right line, 
 for then the upper part of the olecranon comes in contact with the bottom of the olecra 
 nal fossa. The anterior ligament and the anterior and middle bundles of the internal lat- 
 eral hgament are put on the stretch, and thus concur in limiting the movement of exten- 
 sion, which is already limited by the olecranon coming in contact with the bottom of the 
 olecranon cavity. There is no appreciable lateral motion of this joint, the exact fitting 
 of the articular surfaces effectually preventing it.+ 
 
 The Radio-cubital Articulations {figs. 71 to 75). 
 In these articulations, the radius and the ulna are united, 1. By their upper ends {supe- 
 rior radio-cubital articulation) ; 2. By their lower ends {inferior radio-cubital articulation) ; 
 3. By the interosseous ligament through a great part of their extent. 
 
 Superior Radio-cubital Articulation. 
 
 Preparation. — Remove with care the anconeus and the supinator brevis, and separate 
 the forearm from the arm. 
 
 The articular surfaces are the edge of the head of the radius, which is of unequal height 
 in different parts, and the lesser sigmoid cavity of the ulna, which is oblong from before 
 backward, broader in the middle than at the ends, and which forms the bony portion of 
 the osteo-fibrous ring in which the head of the radius rolls. 
 
 The means of union consist of the annular ligament of the radius {e, figs. 71 and 72) 
 
 * [According to the common opinion, the articular surfaces of the radius and ulna are, of course, also cov- 
 ered by the synovial membrane.] 
 
 t A glance at the articulation of the elbow, surrounded by its ligaments, is sufficient to convince us of the 
 facility with which the dislocation of the humerus forward takes place, favoured as it is by the smallness of 
 the antero-posterior diameter of the articulation, and by the deficiency in the resistance of the anterior liga- 
 ment. This dislocation is, next to that of the humerus, the most frequent, notwithstanding the resistance of 
 the brachialis anticus, which, being an active ligament, supports the anterior portion of the articulation, with 
 which it is so closely identified, that, in this dislocation, it is always torn, at least incompletely. This dislo- 
 cation forward is, moreover, favoured in the movement of extension by the point of the olecranon meeting the 
 bottom of the olecranon cavity of the humerus. In a fall upon the wrist, the forearm being extended, the hu- 
 merus becomes a lever of the first kind, whose point of support is represented by the- olecranon cavity of the 
 humerus strongly pressed against by the point of the olecranon ; the lever of power is represented by the whole 
 length of the humerus ; the lever of resistance, by the short portion of the humerus below the olecranon cavity 
 
RADIO-CUBITAL ARTICULATIONS. 143 
 
 This ligament is a band forming three fourths of a ring, which is completed by the lesser 
 sigmoid cavity of the ulna ; it is attached, by its two ends, to the fore and back part of 
 this cavity. Its internal surface, which is smooth and shining like mother-of-pearl, is in 
 contact with the articular border of the head of the radius. The external lateral ligament 
 is attached to its outer surface, and evidently becomes continuous with its posterior half. 
 This arrangement has doubtless given rise to the assertion, that the external lateral lig- 
 ament is attached to the ulna. Those fibres of the anterior ligament which are directed 
 obliquely downward and outward are also inserted into the annular ligament. All these 
 ligamentous attachments retain the annular ligament in its proper position ; when they 
 are divided, it is manifestly retracted towards the neck of the radius, and exposes the ar- 
 ticular edge of the bone. The breadth of the annular ligament is from three to four lines, 
 and its upper circumference is wider than the lower, which construction tends to main- 
 tain the head of the radius in its situation more accurately. With regard to its structure, 
 I would observe, that it is much thicker behind, where it receives the insertion of the ex- 
 ternal lateral ligament, than in front, where it may be much more easily ruptured ; and 
 I am persuaded that, in luxation of the elbow, it is not the external lateral ligament 
 which is most commonly torn, but rather the anterior portion of the annular. 
 
 The synovial capsule is a sort of diverticulum from that of the elbow-joint, which is 
 prolonged upon the inner surface of the annular ligament, and is reflected upward from 
 its lower margin, so as to form a sort of cul-de-sac below it. 
 
 Inferior Radio-cubital Articulation. 
 
 Preparation. — 1. Remove the muscles on both aspects of the forearm. 2. Separate the 
 hand from the forearm so as to expose the lower surface of the triangular ligament, or 
 fibro-cartilage. 3. In order to examine the interior of the joint, saw through the middle 
 of the forearm ; divide the anterior and posterior ligaments ; separate the two bones of 
 the forearm ; cut through the triangular ligament at its insertion into the ulna. 
 
 The articular surfaces are a small sigmoid cavity on the radius, analogous to that which 
 we have described at the upper end of the ulna, and the external two thirds of the cir- 
 cumference of the head of the ulna. This articulation, therefore, is precisely the re- 
 verse of the upper, since in this the ulna furnishes tl\e head, and the radius the sigmoid 
 cavity, while a precisely opposite arrangement obtains in the upper joint. 
 
 The means of union are, 1. Some fibres stretched in front and behind the joint, and call- 
 ed anterior (/, Jigs. 71 and 75) and posterior (ff, Jigs. 72 and 74) ligaments. They form a 
 very imperfect annular ligament. They extend from the anterior and posterior margins 
 of the sigmoid cavity of the radius to the anterior and posterior surfaces of the little head 
 of the ulna, in the neighbourhood of its styloid process. 
 
 2. The triangular ligament, or, rather, cartilage* {i,Jigs. 7i and 73). This is a triangu- 
 lar lamina of cartilage, the apex of which is fixed into the angle formed by the head and 
 styloid process of the ulna, and its base into the lower edge of the sigmoid cavity of the 
 radius. It is thin at the base and the centre, and thick at the apex and the circumfer- 
 ence. It concurs in maintaining the union of the radius and ulna, and performs the office 
 of those inter-articular cartilages which we have noticed as peculiar to such joints as are 
 most exposed to shocks and friction ; and, above all, it restores the level of the inferior 
 radio-cubital surface by filling up the vacancy caused by the projection of the radius be- 
 low the ulna. 
 
 There is a separate synovial membrane for this joint (see above, i. Jig. 75), (often called 
 membrana sacciformis). It covers the upper surface of the triangular ligament, and the 
 sort of incomplete ring which circumscribes the head of the ulna. It forms very loose 
 folds at the places of reflection, which admit of very extensive rotation. This synovial 
 membrane is common to the articulation of the ulna with the radius, and to the articula- 
 tion of the ulna with the inter-articular cartilage ; it is entirely independent of the syno- 
 \ial membrane of the wrist-joint. 
 
 Middle Radio-cubital Articulation, or Interosseous Ligament. 
 The interosseous ligament {I, figs. 71, 72), improperly so called, is an aponeurosis which 
 occupies the interval between the radius and ulna, and which appears to serve princi- 
 pally for the insertion of muscles. It is broader in the middle than at the ends, and does 
 not reach the extremities of the interosseous space, for there is an interval above and 
 below, which serves the purpose of giving passage to nerves and vessels, and also per- 
 mits more free motion between the two bones. The fibres which compose it are direct- 
 ed obhquely downward and inward, i. e., from the radius to the ulna. We generally ob- 
 serve on its anterior aspect several bundles running downward and outward ; the supe- 
 
 * This is the only example in the system of an inter-articulary cartilage serving as a means of union be- 
 tween the bones. Can its principal use be to prevent the dislocation of the ulna in the movements of rotation 1 
 The following experiment will show that this cartilage does not oppose the forcible movements of pronation 
 and supination : Saw the bones of the forearm at their middle line, separate the forearm from the wrist, ro- 
 tate with the utmost force the radius upon the ulna, and it will be sedn that, during these movements, the in- 
 ter-articular cartilage remains unstrained in all its points. This cartilage is attached to the groove of the sty 
 loid process of the ulna by fibrous tissue ; what it called the summit of the triangular cartilage is, therefore 
 Dothing else than a very short and strong little ligament, by which the cartilage is attached to the ulna. 
 
144 ARTHEOLOGY. 
 
 rior and the strongest of these is called the round ligament, or the ligamentous cord of 
 Weitbrecht (m, Jig. 71). It extends obliquely downward and outward, from the outside 
 of the coronoid process of the ulna to the lower part of the bicipital tuberosity of the ra- 
 dius. Its direction is, therefore, precisely the inverse of that of the fibres of the inter- 
 osseous ligament. 
 
 Mechanism of the Radio-cubital Articulations. 
 These articulations, like all trochlear joints, only admit of one kind of motion, viz., 
 rotation, which is here called by a peculiar name. Rotation forward is denominated 
 ■pronation. ; rotation backward is called sjipination. We must examine these in both the 
 upper and the lower radio-cubital articulations. 
 
 Mechanism of the Superior Radio-cubital Articulations. 
 
 Pronation. — In this movement, the inner part of the head of the radius rolls backward 
 upon the lesser sigmoid cavity of the ulna, and may be carried so far that the radius may 
 describe half a circle upon its axis. Notwithstanding the obstacles to displacement re- 
 sulting from the strength of the back part of the annular ligaments, and the presence of 
 the two little hooks, one in front and the other behind the lesser sigmoid cavity of the 
 ulna, and, lastly, notwithstanding the advantage produced by the reception of the small 
 head of the humerus in the cup-like cavity of the upper end of the radius, in violent pro- 
 nation the head of the radius is frequently luxated backward. Perhaps no dislocation is 
 more common in infancy than the incomplete luxation backward of the upper end of the 
 radius, on account of the greater looseness of the annular ligament, and the less com- 
 plete reception of the small head of the humerus in the cupula of the radius. The cause 
 occasioning this displacement is forced pronation, so frequent when infants are held by 
 the hand, in attempting to save them from falling. 
 
 In supination, the head of the radius turns upon its axis in a different direction, i. e., 
 its inner part ghdes forward upon the lesser sigmoid cavity of the ulna. If it be carried 
 too far, dislocation forward may be the consequence.* 
 
 Mechanism of the Inferior Radio-cubital Articulations. 
 
 The movements of pronation and supination, at the lower radio-cubital articulation, 
 are produced by a mechanism which is precisely the inverse of the former ; for the ra- 
 dius, instead of rotating upon its own axis, turns round the head of the ulna by a move- 
 ment of circumduction. This difference results partly from the curvature of the radius, 
 and partly from the great transverse diameter of its lower end, which forms the radius 
 of the arc of the circle which it describes round the ulna. In pronation, the little sig- 
 moid cavity roUs forward on the articular edge of the head of the ulna ; in supination, it 
 glides in the opposite direction, that is, backward. We see, then, that in the lower ar- 
 ticulation, a concave surface moves upon a convex, while the contrary takes place at 
 the upper. • 
 
 Does the inter-articular cartilage limit these motions, as it has been asserted 1 The 
 experiment which I have indicated above shows that this cartilage is in the same con- 
 ditions in regard to the articular surfaces, both in pronation and supination, and that the 
 small ligament which attaches it to the groove of the styloid process of the ulna, expe- 
 riences neither tension nor relaxation. The anterior and posterior ligaments alone are 
 able to limit the movements of rotation by their resistance ; but, in forcible pronation, 
 these may be broken, and the head of the ulna dislocated backward ; in forcible supina- 
 tion, it may be dislocated forward. It should be remarked that, in cases of luxation of 
 the ulna, the head of this bone does not lacerate the capsule, but the capsule is torn upon 
 it ; for, as we shall afterward see, the ulna is immovable at the cubito-carpal joint, and 
 takes no share in the partial motions of the forearm. 
 
 Mechanism of the Radio-cubital Articulations, considered with reference to the Bodies of the 
 
 two Bones. 
 In the movement of pronation, the radius crosses the ulna at an acute angle, so that 
 its lower part is carried in front of the ulna, while the upper remains on the outside. 
 The movement of supination consists in the return of the radius to its state of parallel- 
 ism with the ulna. In pronation, the interosseous ligament is relaxed ; in supination, it 
 is stretched : its absence at the upper part of the forearm, where its place is supphed by 
 the ligament of Weitbrecht, allows more extensive rotatory movements, t 
 
 * This displacement is very uncommon, on account of the hook-like projection at the anterior extremity of 
 the sigmoid cavity, and doubtless, also, because forcible supination is very rjjre. Professor Dng^es informs me 
 that he has seen an instance of this dislocation of the radius, and proved its existence by inspection after 
 death. I have myself recMitly met with a case of an incomplete dislocation forward in a child ; a slight pres- 
 sure from before backward upon the superior extremity of the radius was sufficient to reduce the dislocation, 
 which took place on a sudden, while the child was being dressed. 
 
 t If the interosseous ligament, the fibres of which pass downward from the radius to the ulna, had besn 
 prolonged to the upper part of the interosseous space, it would have much impeded the motions of supination, 
 l)y limiting the movements of the bicipital tuberosity, into which one of the supinator muscles of the forearm, 
 viz., the biceps, is inserted ; but the round ligament being inserted below the bicipital tuberosity, and passing 
 dojwQward from the ulna to the radius, can have no effect in limiting the extent of rotation 
 
RADIO-CARPAL ARTICULATION. 145 
 
 The existence of the interosseous space is an indispensable condition for the peiform- 
 ance of pronation and supination ; and, therefore, every curative plan for the treatment 
 of fractures of the forearm which does not provide for the preservation of this space 
 should at once be rejected. 
 
 In the explanation we have given of the mechanism of the radio-cubital articulations 
 the ulna has been considered as an immovable axis, round which the radius executes 
 below certain movements of circumduction ; but many authors have maintained the 
 opinion that the ulna also takes part in these motions. Without discussing the different 
 theories which have been successively proposed on this subject, we shall mention an 
 experiment which is at once decisive of the question. If all the articulations of the arm 
 be exposed from the shoulder to the hand, and the humerus be immovably fixed in a 
 vice, it will be seen that, when the forearm is pronated or supinated, the radius moves 
 upon the ulna, which remains altogether imdisturbed ; and, also, that any lateral motion 
 of the ulna is absolutely impossible, from its perfect jointing with the humerus at the 
 elbow. When the humerus is not completely fixed, it also rotates in conjunction with 
 the bones of the forearm. 
 
 Lastly, it should be observed that, when the radius is rotated during semiflexion of 
 the forearm, the motion is accompanied by slight degrees of flexion and extension at the 
 elbow-joint. 
 
 Radio-carpal Articulation {figs. 73 to 75). 
 
 Preparation. — Divide the fibrous sheaths of the flexor and extensor tendons, and care- 
 fully remove those tendons ; bearing in mind the fact that the fibrous sheaths closely ad- 
 here to the ligaments, or, rather, are identified with them, and may be considered as an 
 appurtenance of the ligamentous apparatus of the joint. 
 
 This articulation belongs to the class of condylarthroses. 
 
 The articular surfaces (fig. 73) are those of the scaphoid, the semilunar, and the cunei- 
 form, which together form a condyle, oblong transversely, and covered by articular car- 
 tilages, which are prolonged farther on the posterior than on the anterior aspect of the 
 bones, and the transversely oblong concave, articular surface, formed by the lower ends 
 of the radius and ulna. The radius, which forms by itself two thirds of the surface, cor- 
 responds to the scaphoid and semilunar, and presents an antero-posterior ridge, and a 
 slight contraction from before backward, opposite the interval between these two bones. 
 The ulna corresponds to the cuneiform bone, with the intervention of an inter-articular 
 cartilage, viz., the triangular cartilage already described, which performs the part both of 
 a hgament and an inter-articular cartilage. The concave surface presented by the lower 
 part of the forearm is completed at the sides by the styloid processes of the radius and ulna. 
 
 Means of Union. — There are for this joint an external lateral hgament, an internal lat- 
 eral, two anterior, and one posterior hgament. 
 
 The external lateral ligament {a, figs. 73, 74, 75) stretches from the summit, and forms 
 the neighbouring parts of the styloid process of the radius to the outer part of the scapho- 
 id, where it is inserted by a broad attachment immediately on the outside of the radial ar- 
 ticular surface of that bone. This ligament, which is not very thick, is continuous with 
 the anterior and the posterior ligament, without any line of demarcation being perceived. 
 
 The internal lateral ligament. It is uncovered immediately after the tendinous sheath 
 of the extensor carpi ulnaris has been divided. It is lined by the synovial membrane of 
 this sheath. It is a cylindrical chord, commencing at the styloid process, of which it 
 seems to be a continuation, and dividing inferiorly into two fasciculi, one of which is at- 
 tached to the pisiform, the other, which is more considerable, to the posterior surface of 
 the cuneiform bone. This chord first appears very thick ; but, on dividing it, it is seen 
 perforated by a cavity communicating inferiorly with the radio-carpal articulation, and its 
 superior extremity is not attached to the summit of the styloid process of the ulna, but to 
 the middle point of this process, in the form of a demi-capsule. The summit of this pro- 
 cess is articular, and surrounded with a thick layer of cartilage ; it is farther contained 
 in the synovial membrane of the wrist, and is in direct relation with the cuneiform bone. 
 The styloid process of the ulna is therefore the only portion of this bone which enters di- 
 rectly into the wrist-joint. 
 
 The anterior ligaments are two in number, one radial, the other ulnar. 
 
 The radio-carpal hgament forms a broad layer resembling mother-of-pearl, which ap- 
 pears as soon as the flexor tendons have been removed. It is composed of bundles, which 
 are often separated by adipose cellular tissue and vessels, so that I considered it neces- 
 sary, in the former edition of this work, to describe three anterior radial bundles, an ex- 
 ternal, a middle, and an internal ; I have abandoned this distinction, because it does not 
 appear of any use. This ligament arises from the whole breadth of the anterior border of 
 the inferior extremity of the radius around the articular surface ; it also arises from the 
 anterior border of the styloid process of this bone. Hence its fibres stretch from above 
 downward, and from without inward, approximating to a horizontal position, in proportion 
 as they are more elevated. The most external fibres go to the os unciforme and the os 
 magnum ; those which come next are inserted into the scaphoid bone ; others, again, into 
 
 T 
 
146 ARTHEOLOGY. 
 
 the cuneiform and the pisiform bones. The most elevated fibres, which ire the most in- 
 ternal, seem to be continuous with the anterior ligament of the inferior "adio-cubital ar- 
 ticulation. The most external bundles of this ligament are tl e thickest. This ligament 
 is composed of several layers of fibres, the most superficial cf which are the longest. 
 
 The ulnar-carpal ligament has probably been conjfounded by authors with the internal 
 lateral Ugament ; or perhaps it may have escaped their notice altogether, on account of 
 its being deeply seated. This ligament arises, by a narrow extremity, from the groove 
 which separates the styloid process from the little head of the ulna, in front of the small 
 ligament which forms the summit of the inter-articular cartilage ; thence it goes down- 
 ward and outward, passes under a few fibres of the anterior radio-carpal ligament, and ■ 
 lost by irradiating. The horizontal superior fibres describe a curve beneath the head o- 
 the idna, and are inserted into the anterior border of the radius, where they are confound- 
 ed with the fibres of the radio-carpal ligament ; the inferior fibres descend almost verti- 
 cally downward, externally to the pisiform bone, and terminate in the os cuneiforme. 
 
 The posterior ligament cannot possibly be separated from the fibrous sheath of the ex- 
 tensor and radial tendons, with which it is continuous. There is but one posterior liga- 
 ment ; it is much weaker and narrower than the anterior radio-carpal ligament, and 
 stretches obhquely from the posterior border of the radius to the posterior faces of the 
 cuneiform and the semilunar bones. The bundle which goes to the cuneiform is the 
 stronger. This ligament covers about the third portion of the joint, while the radio-car- 
 pal ligament covers the whole of the anterior surface. It should be observed, that there 
 is a marked predominance of the anterior over the posterior ligaments, both in the artic- 
 ulation of the hand with the forearm, and in the articulations of the carpus. 
 
 With regard to the anterior and posterior ligaments of the radio-carpal articulation, I 
 shall make an observation which may be of some interest : it is, that all these ligaments, 
 with the exception of the cubito-carpal, come from the radius, and closely unite the inferior 
 extremity of that bone to the first range of the carpus, and, consequently, to the hand. 
 
 The synovial membrane (see Jig. 73) is loose behind, where it is only partially covered 
 by the ligaments we have described ; throughout the whole of the remaining circumfer- 
 ence of the joint it is strengthened by scattered ligamentous fibres, which some anato- 
 mists have described as a capsular ligament. This synovial membrane sometimes com- 
 municates with that of the lower radio-cubital articulation, by an opening at the place o 
 union of the triangular cartilage with the lower edge of the sigmoid cavity of the radius. 
 It also sometimes communicates with the general synovial membrane of the carpus, by 
 the interosseous spaces which separate the bones of the first carpal row. 
 
 Besides the means of union which we have described, the flexor tendons in front, and the 
 extensor tendons behind, should be noticed, as serving to increase the strength of the joint. 
 
 Mechanism of the Radio-carpal Articulation. 
 
 This articulation belongs to the condyloid class, and has, therefore, four motions, viz., 
 flexion, extension, abduction, and adduction, and by passing from one of these to the 
 other, it can perform circumduction. 
 
 1. Flexion. — In this motion, the condyle formed by the first row of the carpus glides 
 Ibackward upon the lower end of the forearm. The posterior ligaments and the exten- 
 :Sor tendons are put on the stretch. When the movement of flexion is carried too far, 
 luxation may take place by laceration of the posterior ligament, and then the lower end 
 of the two bones of the forearm pass in front of the articular surface of the bones of the 
 first row of the carpus. The possibility of dislocation of this joint has been doubted ; 
 but I have seen two instances of this kind of dislocation, which were incontestable. 
 
 2. In extension, the condyle formed by the carpus roUs forward upon the lower end of 
 the forearm ; and as the articular surface of the carpus reaches farther on the back than 
 in .front, it follows that extension may be carried farther than flexion: it is limited by 
 the strong anterior ligaments, and also by the lateral ligaments, which, as is generally 
 observed, are attached nearer to the side- of flexion than to that of extension. 
 
 It should also be remarked, that extension is the easiest motion of the hand upon the 
 forearm : this may be readily understood from the great power which the hand possess- 
 es when it forms a right angle behind with the forearm.* 
 
 3. In abduction, the condyle formed by the carpus rolls in the direction of its length, 
 t. c, transversely and from without inward, while the radial edge of the hand is inchned 
 towards the radial edge of the forearm : this motion is limited by the mutual meeting of 
 the styloid process of the radius, and the external process of the scaphoid. 
 
 4. In adduction, the ulnar edge of the hand is bent towards the ulnar edge of the fore- 
 ; arm ; the motion is limited by the meeting of the summit of the styloid process of the 
 
 ulna and the cuneiform bone, and also by the tension of the external lateral ligamsnt. 
 It may be easily conceived, that in the lateral movements, which are performed in 
 
 * We should observe that it is almost impossible to separate the mechanism of the carpal articulations 
 irom that of the radio-carpal joint ; the latter is noticed here by itself only in order to conform with the ana 
 toicical divisions. 
 
ARTICULATIONS OF THE CARPUS. 147 
 
 the direction of the long diameter of the articular surfaces, dislocation must be very dif 
 ficult, and that, when it does occur, it must be incomplete. 
 
 The movement of circumduction is nothing more than a succession of the different m» 
 tions which have been already pointed out. The hand describes a cone, of greater ex 
 tent behind, that is, in the direction of extension, than in front, or in the direction o» 
 flexion. It is also still more restricted in adduction and abduction. 
 
 Articulations of the Carpus (figs. 73 to 75). 
 These articulations comprise, 1. The articulations of the bones of each row together 
 and, 2. The articulations of the two rows. 
 
 Articulations of the Bones of each Row. 
 
 Preparation. — 1. Remove the extensor and the flexor tendons ; 2. Separate the hand 
 from the forearm, then the first row from the second, and, lastly, the bones of both rows 
 from each other, examining their means of union before completing the separation. 
 
 Articular Surfaces. — The articulations of the bones of each row are amphi-arthroses, 
 and, consequently, present one part continuous and another contiguous. The bones of 
 the first row correspond to each other by oblique surfaces, those of the second row by 
 vertical and more extensive surfaces. 
 
 Means of Union. — Two classes of ligaments belong to these joints : the one is extend- 
 ed between the corresponding surfaces, the interosseous ligaments; the other set are 
 peripheral, and are divided into palmar and dorsal. 
 
 The palmar and dorsal ligaments are fibrous bundles, stretched transversely or oblique- 
 ly from each of the bones of the carpus to those which are contiguous to it. The dorsal 
 are much thinner than the palmar. 
 
 The interosseous ligaments are not disposed in an exactly similar manner in the two 
 rows, and we shall, therefore, examine them separate- ^ 73 
 
 ly. 1 . The interosseous Ugaments of the first row (e e, 
 fig. 73) occupy only the upper part of the corresponding u 
 facettes ; they are nothing more than small fibrous bun- \' 
 dies, one extending from the scaphoid (1) to the semi- 
 lunar (2) ; the other from the semilunar to the cunei- 
 form (3) ; they are sometimes partially interrupted, and 
 present openings, which establish a communication be- 
 tween the general synovial membrane of the carpus 
 and that of the radio-carpal articulation. These inter- 
 osseous ligaments are reddish, scarcely fascicidated, 
 very loose, so as to admit of pretty extensive gliding 
 motions. 2. The interosseous ligaments {d d d) of the 
 second row are much thicker than those of the first ; 
 the whole non-articular portion of the corresponding 
 facettes gives insertion to these Ugaments, which are 
 very compact, and of a much more dry and close tex- 
 ture than the reddish tissue connecting together the bones of the fii-st row. It follows, 
 therefore, that the bones of the second row are more firmly united than those of the first, 
 whose interosseous ligaments are loose, and permit a certain degree of mobility. The 
 articulation of the pisiform bone with the cuneiform merits a special description. 
 
 Articulation of the Pisiform and Cuneiform Bodies. 
 
 For this articulation, the pisiform bone presents a single articular surface, which 
 unites with the auterior facette of the cuneiform bone. There are four ligaments in 
 this little joint, which is nothing else but a loose arthrodia : 1. Two inferior {e,fig. 75), 
 which are very strong, viz., an external, stretched obliquely from the pisiform to the 
 hook-like process of the unciform bone ; and an internal, vertical, which is inserted into 
 the upper end of the fifth metacarpal bone. These two ligaments appear partly to re- 
 sult from the bifurcation of the tendon of the flexor carpi ulnaris, this tendon being in 
 the place of the superior ligament, which is wanting. The internal lateral ligament of 
 the radio-carpal articulation may also be considered as entering into the structure of the 
 superior ligament. 2. An anterior and a posterior ligament, thin and radiating, which 
 strengthen the synovial capsule in front and behind. 
 
 The synovial capsule is, most commonly, a small isolated pouch ; and sometimes it is 
 a prolongation of the radio-carpal synovial membrane. This capsule is ver>' loose, and 
 the ligaments are not very tight ; hence the great mobility of the articulation. 
 
 Articulation of the two Rows of Carpus together. 
 
 The articulation of the two rows of the carpus together presents an enarthrosis in the 
 middle, and an arthrodia on each side. 
 
 The articular surfaces consist of a head or spherical eminence received into a cavity, 
 constituting the enarthrosis, and of plane surfaces on the inside and the outside, whick 
 form a double arthrodia. The head is formed by the os magnum (6<fig ^^^ ^"^ ^■he su- 
 
148 ARTHROLOGY. 
 
 perior process of the os unciforme (7) : the cavity is constituted by tne inferior surfaces 
 of the scaphoid (1), the semilunar (2), and the cuneiform (3) bones. This cavity, which 
 is deeply notched in front and behind, is completed in these situations by two ligaments, 
 an anterior and a posterior, which might be called glenoid ligaments, considering their po- 
 sition on the edge of a cavity, and their use in increasing its depth. 
 
 The posterior glenoid ligament is composed of transverse fibres, which are inserted into 
 the first row, closing up the posterior notch. 
 
 The anterior glenoid ligament, much stronger than the other, belongs to the second 
 row ; it is confounded with the anterior ligaments of the articulation, between the two 
 rows, and extends transversely from the os unciforme to the trapezium, passing in front 
 of the neck and the head of the os magnum. Besides these ligaments, we also find, 1 
 An anterior ligament (i, fig. 75), which is very thick, and stretches from the anterior sur- 
 face of the OS magnum, by diverging rays, to those three bones of the first row that form 
 the enarthrodial cavity, in which the head of the os magnum is received, viz., the sca- 
 phoid, the semilunar, and the cuneiform. 2. A posterior ligament (i, fig. 74), which con- 
 sists merely of some fibres extending obliquely from the bones of the first row to those 
 of the second. 
 
 On the inside and the outside of this carpal enarthrosis we find an arthrodia. On the 
 tnside is the articulation of the cuneiform (3, fig. 73) with the unciform (7) bone, consti- 
 tuted by plane surfaces, and strengthened by a very thin posterior ligament, an anterior 
 ligament, much thicker than the preceding, and an internal lateral ligament (c). On the 
 outside is the articulation of the scaphoid with the trapezium and the trapezoid. The ar- 
 ticular surface of the scaphoid (1) is a sort of head or elongated convexity, and those of 
 the trapezium (4) and the trapezoid (5) are two facettes, that unite in forming a concavity, 
 into which the convexity of the scaphoid is received. This small articulation is strength- 
 ened by two anterior ligaments, both of which proceed from the scaphoid, and are connected 
 one to the trapezium, and the other to the trapezoid ; and two posterior, arranged in a sim- 
 ilar manner with the preceding, but much thinner. 
 
 A single synovial capsule (see fig. 73), very loose, especially behind, covers the corre- 
 sponding articular surfaces of the two rows. But it is also provided with small culs-de- 
 sac, which penetrate into the intervals between the bones of each row, there being tliree 
 below and two above. 
 
 Mechanism of the Carpus. 
 
 The mechanism of the carpus must be considered as providing both for strength and 
 mobility. The conditions favourable to strength are, 1. The number of bones in the car- 
 pus ; 2. The reciprocal dovetailing of the two rows, the anti-brachial row joining in this 
 fashion the metacarpal, and vice versa ; 3. The numerous ligaments connecting the bones 
 of each row together. The carpus, therefore, has power to resist the most violent shocks, 
 chiefly on account of the expenditure offeree at each of its numerous articulations. With 
 regard to mobility, the movements between the bones of each row must be distinguished 
 from those which take place between the two rows. 1. The partial movement between 
 the component bones of each row is scarcely appreciable, and requires no consideration. 
 2. The mobility of the two rows upon each other is, however, more marked. The enar- 
 throdial articulation of the head of the Os magnum can only perform forward and backward 
 motions, for the arthrodial joints on each side prevent any lateral movements. 
 
 Mechanism of the Carpal Enarthrosis. — The movement of extension is very limited, on ac- 
 count of the resistance of the anterior ligaments. The movement of flexion, on the con- 
 trary, is much more considerable : it may be carried sufficiently far to cause luxation of 
 the head of the os magnum backward. The slight structure and the looseness of the pos- 
 terior hgaments, and also the looseness of the synovial membrane behind, explain the fa- 
 cility which this articulation enjoys in the movements of flexion. It is of importance to 
 remark, that the carpal enarthrosis performs a more active part in the flexion of the hand 
 than even the radio-carpal articulation ; a circumstance of the highest interest in relation 
 to the mechanism of the carpus. 
 
 Metacaep.vl Articulations. 
 The metacarpal bones are united at their extremities, but separated along their shafts. 
 We shall examine the articulations, 1. Of their carpal ; and, 2. Of their digital extremities. 
 
 1. Articulations of the Carpal Ends of the Metacarpal Bones. 
 
 These are symphyses or amphi-arthroses. The articular surfaces {see fig. 73) occupy the 
 sides of the carpal ends of the metacarpal bones, and are partly contiguous and partly con- 
 tinuous. The contiguous portion consists of a facette covered with cartilage, and is, in 
 fact, an extension of the surface that articulates with the carpus. The part intended to 
 become continuous is rough. 
 
 The means of union are the interosseous, the dorsal, and the palmar ligaments. The inter- 
 osseous ligaments (//, fig. 73) are short, close, and very strong bundles of fibres, interposed 
 between the rough portions of the lateral facettes of two neighbouring metacarpal bones. 
 They constitute the principal means of uniting these bones, as may be seen by attemptinfl 
 
METACARPAL ARTICULATIONS. 
 
 149 
 
 Fig 74. 
 
 to separate them after dividing the dorsal and pahnai 
 ligaments. 
 
 The dorsal {I, fig. 74) and palmar ligaments (m, fig. 75) 
 consist of fibrous bundles, stretched transversely from 
 one metacarpal bone to another. The palmar ligaments 
 are much larger than the dorsal. 
 
 2. Articulation of the Digital Ends of the Metacarpal 
 
 Bones. 
 Although the digital extremities of the metacarpal 
 bones are not, prop- 
 erly speaking, artic- 
 ulated together, yet 
 as they are contigu- 
 ous, and move upon 
 each other,their sur- 
 faces are covered 
 by a synovial mem- 
 brane, which facil- 
 itates their move- 
 ments ; moreover, a 
 palmar ligament (n. 
 Jigs. 74, 75) is stret- 
 ched transversely 
 in front of these ex- 
 tremities, and unites them loosely together. This lig- 
 ament (called also transverse) is common to the last 
 four metacarpal bones, but it does not reach the met- 
 acarpal bone of the thumb. It may be considered as 
 formed by the union of all the anterior ligaments ot 
 the metacarpo-phalangal articulations, and as being 
 destined to render these ligaments continuous. In 
 order to expose this ligament, and to study with atten- 
 tion its connexions with the anterior ligaments of the 
 metacarpo-phalangal articulation, it is sufficient to 
 open the fibrous sheaths of the flexor tendons of the fingers, and to remove the smalllura- 
 bricales muscles, together with the nerves and vessels of the fingers. 
 
 We may consider the interosseous palmar aponeurOsity as representing, in respect to 
 the shafts of the metacarpal bones, the aponeurosis called the interosseous ligament in 
 the forearm. Strictly speaking, the thickened inferior border of the dorsal interosseous 
 aponeurosis, which is continuous with the tendons of the extensor muscles, might be con- 
 sidered as a dorsal transverse ligament, much weaker than the preceding. 
 
 The interosseous muscles, as we shall afterward see, complete the means of union of 
 the metacarpal bones. 
 
 Carpo-metacarpal Articulations. 
 The articular surfaces are the inferior facettes on the bones of the second row of the 
 carpus, and the facettes on the upper ends of the metacarpal bones. We may consider 
 all the carpo-metacarpal articulations as forming only one joint with a broken surface. 
 The articulation of the trapezium with the metacarpal bone of the thumb, and that of the 
 fifth metacarpal bone with the os unciforme, require each a special description. 
 
 Articulations of the Second, Third, and Fourth Metacarpal Bones with the Carpus. 
 
 Articular Surfaces {see fig. 73). — ^The articulation of the second, third, and fourth met- 
 acarpal bones with the carpus presents a sinuous line, which might, perhaps, be sub- 
 jected to certain rules of disarticulation, if this disarticulation seemed to be of the least 
 use. It constitutes a tight arthrodia, with an angular surface. Proceeding from within 
 outward, the fourth and third metacarpal bones form a regular curve, with the concavity 
 looking upward ; but the second, which unites by three facettes with the trapezium, the 
 trapezoid, and os magnum, presents an angular surface. The second metacarpal bone 
 is jointed, by its transversely concave surface, Avith a facette on the trapezoid, which is 
 concave, but in the opposite direction, and by two lateral facettes, with the os magnum 
 and the trapezium, so that it enters, as it were, into the carpus by two angular projec- 
 tions, which are received into the intervals between the three bones with which it is 
 articulated. From this it follows, that the carpo-metacarpal articulations present not 
 only concave and convex surfaces, favourable to mobility, but also angular surfaces thai 
 evince the immobility of these joints. 
 
 Means of Union. — Some ligaments, distinguished as dorsal and palmar, both very 
 strong, short, and compact, retain the articular surfaces as immovably in contact as if 
 the joints we-e symphyses. 
 
150 ARTHEOLOGY. 
 
 The dorsal ligaments are much stronger than the palmar, and are composed of several 
 layers, the deepest being the shortest. There are three dorsal ligaments for the second 
 metacarpal bone : a median (o, fig. 74), stretched to it from the trapezoid bone ; an exter- 
 nal (p), which comes from the trapezium, and covers the insertion of the extensor carpi 
 radialis longior ; and an internal, arising from the os magnum : the first of these is ver- 
 tical, tlie last two are oblique. There are two dorsal ligaments in the articulation of the 
 third metacarpal bone : a vertical, which comes from the os magnum ; and an oblique (r), 
 from the OS unciforme. 
 
 In the articulation of the fourth metacarpal bone there is one dorsal ligament, longer 
 and looser than the preceding. 
 
 The palmar ligainents are much less marked than the preceding ; contrasting thus with 
 the palmar ligaments of the carpus. There is none for the second metacarpal bone ; the 
 tendon of the flexor carpi radialis appears to supply the place of this ligament. There 
 are three ligaments for the third metacarpal bone : an external, which comes from the 
 trapezium ; a middle, proceeding from the os magnum ; and an internal, from the os unci 
 forme. Lastly, for the articulation of the fourth metacarpal bone, there is one palmar 
 ligament from the os unciforme. 
 
 The synovial membrane (see fig. ""rQ) of the carpo-metacarpal articulations is a continu 
 ation of the synovial membrane of the carpus, and is prolonged between the upper ends 
 of the metacarpal bones ; and, as the synovial membrane of the carpus communicates 
 also with the radio-carpal joint, it can be conceived what ravages may be produced by 
 inflammation attacking any one of these parts. I must here point out an interosseous, or 
 lateral ligament (I, fig. 73), which arises from the os magnum, and slightly, also, from 
 the OS unciforme, and is attached to the inner side of the third metacarpal bone. It al- 
 most completely isolates the articulations of the last two metacarpal bones. This liga- 
 ment being attached to the third metacarpal bone, which is already provided with very 
 strong ligaments, increases in a remarkable manner the strength of the joint. 
 
 Carpo-metacarpal Articulation of the Thumb.- — This joint {m,fig. 73), which is very dis- 
 tinct and completely separated from all the others, is remarkable, also, for the arrange- 
 ment of the articular surfaces. There is a mutual jointing between the trapezium, which 
 is concave transversely, and convex from behind forward ; and the first metacarpal bone, 
 which is concave and convex in precisely opposite directions. It is the type of all ar- 
 ticulations by mutual reception. 
 
 The m£ans of union consist of a capsular ligament {s, figs. 74 and 75), imperfect on the 
 outside, where its place is occupied occasionally by the tendon of the abductor longus 
 pollicis (extensor ossis metacarpi poUicis) : it is much thicker behind than in front, and 
 is sufficiently loose to permit extensive motions in all directions. There is a separate 
 synovial membrane for this joint, which is remarkable in respect of its relations : viz., 1. 
 Behind, with the extensor muscles of the thumb ; 2. On the outside, with the expanded 
 tendon of the abductor pollicis ; 3. On the inside, with the interosseous muscles and the 
 radial artery, where that vessel penetrates into the palm of the hand, to form the deep 
 palmar arch ; and, 4. In front, with the muscles of the baU of the thumb. 
 
 Carpo-metacarpal Articulation of the fifth Metacarpal Bone {see fig- 73). — The articulation 
 of the fifth metacarpal bone with the os unciforme is, in many respects, analogous to the 
 preceding ; for there is here, also, a sort of mutual reception between their correspond- 
 ing articular surfaces. There is, also, a kind of capsular ligament {t, fig. 74), very strong 
 in front and thin behind, and incomplete on the outside, on account of the presence of 
 the fourth metacarpal bone : it is rather loose, and maintains the relation of the articular 
 surfaces. The tendon of the extensor carpi ulnaris strengthens this joint behind, in the 
 same manner as the tendon of the long abductor of the thumb strengthens the articula- 
 tion of the trapezium and the first metacarpal bone. 
 
 The synovial membrane of this joint belongs also to the fourth metacarpal bone. The 
 fourth and fifth metacarpal bones may, indeed, be strictly considered as forming only one 
 joint, and the lateral interosseous ligament as completing the capsular ligament. On 
 the other hand, the second and third metacarpal bones form a very distinct articulation 
 with the OS magnum, the trapezoid, and a small facette upon the trapezium ; lastly, there 
 is another joint peculiar to the first metacarpal bone and the trapezium. There are thus 
 three distinct joints (see fig. 73) in the carpo-metacarpal articulation, in one of which 
 the articular surfaces are simple, while in the two others they are broken. 
 
 Mechanism of the Carpo-metacarpal Articulations. 
 
 The mechanism of the carpo-metacarpal articulations should be studied, both as re- 
 gards strength and mobility. 
 
 I. With regard to strength, the metacarpal bones mutually support each other, and resist 
 in common the action of external agents : they can only be broken, therefore, by violence 
 suflicient to fracture several at the same time. In order that any one should be broken 
 alone, the violence must be applied directly to it. In this manner I have seen the third 
 metacarpal bone fractured by the stick of a rocket. 
 
 The great strength of the metacarpus depends not only on the simultaneous resistance 
 
ARTICULATIONS OP THE FINGERS. '1^1 
 
 ot its component parts, but also on the intervening articulations, each of which becomes 
 the seat of a certain expenditure of force ; for part of this being employed in moving the 
 articular surfaces upon each other, is necessarUy lost as far as its direct transmission is 
 concerned. 
 
 With regard to mobility, these articulations, which might be called tight angular arthro- 
 dias, are only possessed of slight gUding motions, on account of the angular disposition 
 of the articular facettes, the sinuosity of the common articular line, and the strength and 
 shortness of both the external and the interosseous ligaments. At the same time the 
 mobility of all the metacarpal bones is not equal. Thus, the articulation of the trape- 
 zium with the first metacarpal bone holds the first rank ; it is in some degree different 
 from the others in this respect as well as in position, and merits particular description. 
 The articulation of the fifth metacarpal bone holds the second place, and that of the 
 fourth the third. The articulations of the second and third metacarpal bones are as im- 
 movable as symphyses. 
 
 Mechanism of the Articulation of the Trapezium and the first Metacarpal Bone. — From the 
 mutual reception of the articular surfaces, this articulation permits four motions, viz., flex- 
 ion, extension, abduction, and adduction, and, as a consequence of these, circumduction. 
 
 Flexion is not performed directly, but obliquely inward and forward. This obhque mo- 
 tion produces the inovement of opposition, which characterizes the hand ; it is very exten- 
 sive, and, when carried too far, may produce luxation backward with the greater facility, 
 because the capsular hgament is very thin in that direction. Extension may be carried 
 so far that the first metacarpal bone may form a right angle with the radius. It is con- 
 ceivable that luxation forward might be produced by this motion ; but there are very few 
 causes that would tend to increase extension to such a degree, and, moreover, the ante- 
 rior part of the capsular ligament is extremely strong, so that no example of this luxa- 
 tion has ever been recorded. 
 
 Abduction is very extensive ; when carried beyond a certain point, it may give rise to 
 dislocation inward, for the trapezium, being situated on a plane anterior to the root of the 
 metacarpus, the neighbouring metacarpal bones offer no obstacle to such a displacement. 
 
 Lastly, direct adduction is limited by the meeting with the second metacarpal bone. 
 
 Mechanism of the Articulation of the fifth Metacarpal Bone with the Cuneiform. — This ar- 
 ticulation in some degree resembles the preceding, and, like the last, it would be liable 
 to dislocation, were it not for its intimate connexions with the other metacarpal bones, 
 so that the same cause that would tend to displace the fifth metacarpal bone would also 
 tend to displace the fourth. 
 
 Articulations of the Fingers (.figs. 74 and 75). 
 
 These comprise, 1. The articulations of the fingers with the metacarpal bones. 2. The 
 articulations of the phalanges together. 
 
 Metacarpo-phalangal Articulations. 
 
 These belong to the class of condyloid articulations. 
 
 The articular surfaces in each are formed by the head of the metacarpal bone, flattened 
 from side to side, increasing in breadth from the dorsal to the palmar aspect, and pro- 
 longed much farther in the latter direction, where it presents the trace of a division into 
 two condyles ; and by the shallow glenoid cavity of the first phalanx, which is trans- 
 versely oblong, and, consequently, has its long diameter at right angles to tliat of the head 
 of the metacarpal bone, which is oblong from before backward. We see, then, that an 
 articular head, elongated from before backward, is adapted to a transversely oblong cav- 
 ity. This arrangement favours the movements of flexion and extension, as well as the 
 lateral motions, which are as extensive as they would have been had all the diameters 
 of the articular surfaces been equal to those which are actually the longest. 
 
 It is on account of the lateral flattening of the heads of the metacarpal bones that, in 
 amputations at these joints, surgeons make choice of lateral, in preference to antero- 
 posterior flaps. 
 
 Means of Union. — On account of the disproportion just noticed as existing between 
 the articular surfaces of this joint, the glenoid cavity of the first phalanx not being equal 
 to more than one half of the articular surface on the metacarpal bone, this cavity is pro- 
 vided with a ligament called the anterior ligament {u,f.g. 75), which was confounded by 
 the older anatomists with the fibrous sheaths of the flexor tendons. This ligament I 
 have called the glenoid ligament, and its use is to complete the cavity of reception ol 
 the metacarpal condyle. It is situated on the palmer aspect of the joint, and is grooved 
 anteriorly, to correspond with the flexor tendons. It is concave, forming, so to say, a 
 demi-capsule behind, to correspond with the metacarpal condyle. By its edges it is con- 
 tinuous not only with the transverse metacarpal ligament, which is one ol' its appurte- 
 nances, but also with the sheath of the flexor tendons, and with the lateral ligaments of 
 the joint. By its superior border this ligament is continuous with the palmar interos- 
 seous aponeurosis, and with the digital bands of the palmar aponeurosis. By its lower 
 edge it is finnly fixed to the anterior part of the margin of the first phalangal articular 
 
152 ARTHROLOGY. 
 
 surface ; its upper edge is loosely connected by some ligamentous fibres to the contract 
 ed neck which supports the head of the metacarpus, and is accurately adapted to that 
 neck. The anterior or capsular ligament is very thick, unyielding, formed of fibres that 
 cross each other, and look like mother-of-pearl, and is as compact as cartilage. Several 
 times I have found a sesamoid bone in the substance of the anterior ligament of the in- 
 dex and the middle finger. The whole tendinous sheath of the tendons of the flexor 
 muscles may be considered as making part of this anterior ligament, and we ought not 
 to overlook these tendons in estimating the solidity of the joint with regard to flexion. 
 This joint has two lateral ligaments, which are extremely unyielding, an internal and an 
 external ; they are inserted into a marked tubercle existing posteriorly on each side of 
 the lower extremities of the metacarpal bones, and into a very remarkable depression 
 below and before this tubercle ; hence these ligaments extend very obliquely from be- 
 hind forward and from above downward, in the shape of a strong and flat band, looking 
 like mother-of-pearl, which continually expands and irradiates, and finally terminates, 1 . 
 In a tubercle existing anteriorly, and on each side of the margin of the upper end of the 
 first phalangal bone. 2. By its superior fibres into the borders of the anterior ligament. 
 
 These lateral ligaments extend, therefore, obUquely from the posterior tubercle of the 
 lower end of the metacarpus to the anterior tubercle of the upper end of the first phalan- 
 gal bone ; they are stretched by flexion, which cannot be extended beyond the right 
 angle without the ligaments being torn ; and they are relaxed by extension, except that 
 portion of these ligaments which goes to the anterior ligament, and which limits the ex- 
 tension by its resistance. It may be interesting to remark, that the external lateral lig- 
 ament is much stronger than the internal ; the former of these ligaments is inserted not 
 only into the tubercle, but also into the whole extent of the subjacent depression. 
 
 There is no dorsal ligament properly so called ; its place is evidently supplied by the 
 corresponding extensor tendon (lo, fig. 74). This extensor tendon, after having reach- 
 ed the level of the joint, becomes nan-ow, and contracts, as it were, upon itself, in order 
 to form a thick and extremely compact cord. From each edge of this ligament an apo- 
 neurotic expansion arises, which is inserted into the sides of the joint. 
 
 The synodal capsule is extremely loose, especially on the aspect of extension ; it does 
 not adhere to the tendon, but is folded upon itself during extension, and is stretched du- 
 ring flexion : it lines the inner surface of the lateral ligaments, and is reflected upon the 
 articular cartilages. 
 
 Metacarpal-phalangal Articulation of the Thumb. — Two sesamoid bones (x, figs. 73 and 
 75) are annexed to this articulation in front, and are constantly found in the glenoid lig- 
 ament ; they aflJbrd insertion to the lateral ligaments and to aU the short muscles of the 
 thmnb. 
 
 If we examine these articulations in connexion, we shall find that they are disposed 
 in a curved line, with the convexity looking downward. This curvature is slightly in- 
 terrupted at the articulation of the fourth metacarpal bone, which is not on a level with 
 those of the index and the middle fingers. 
 
 Mechanism of the Metacarpo-phalangal Articulations. 
 
 We shall take as an example the metacarpo-phalangal articulation of the middle fin- 
 ger. From the arrangement of the articular surfaces, it is evident that this articulation 
 can execute movements in four principal directions, and, consequently, those of circum- 
 duction also. From a simple inspection of the surfaces, it might be inferred that the 
 movement of flexion must be very extensive, while that of extension (or flexion back- 
 ward) and the lateral motions of abduction and adduction are exceedingly limited. The 
 arrangement of the ligaments amply confirms these suppositions. It should be noticed, 
 as a rare exception, that in the movements executed by this joint, it is not the head that 
 moves upon the cavity, but the cavity that moves upon the head. 
 
 In flexion, the first phalanx glides forward upon the head of the corresponding metacar- 
 pal bone ; the extensor tendon and the back of the synovial capsule are stretched by the 
 projecting head of this bone : the posterior fibres of the lateral ligaments are also stretch- 
 ed ; they limit the movement of flexion, allowing it only to proceed so far that the pha- 
 lanx forms a right angle with the metacarpal bone. Lastly, flexion can be carried some- 
 what farther by the thumb, the ring, and the little fingers, than by the others. In ex- 
 tension, the phalanx glides backward upon the head of the metacarpal bone supporting it : 
 this head corresponds almost entirely with the anterior ligament, which, as we have seen, 
 is disposed in the shape of a fibrous demi-capsule. The posterior fibres of the lateral 
 ligaments are relaxed, and the anterior stretched. The motion is evidently limited by 
 the anterior or capsular ligament, and by the anterior fibres of the lateral ligaments, 
 which are inserted into this anterior ligament. I may remark, that the upper border of 
 this anterior ligament forms a sort of ring or collar, which surrounds ahnost entirely the 
 neck of the corresponding metacarpal bone, without adhering to it. 
 
 According to the relative size of this ring, and the comparative looseness of the glenoid 
 ligament, will the movement of extension be more or loss considerable. In all persons 
 \t may be carried so far as to form *n obtuse angle behind ; in some, until a right anglo 
 
ARTICULATIONS OF THE FINGERS. 153 
 
 is formed ; and in a few, even so far as to produce an incomplete luxation, reducible by 
 the sliglitest muscular effort. If extension be carried beyond these limits (for which, 
 however, considerable violence is necessary), the head of the metacarpal bone will escape 
 from the kind of collar formed by the superior border of the capsular ligament and the 
 anterior fibres of the lateral ligaments, sometimes by extensively lacerating it, but at 
 others only by stretching it very much ; in both cases the first phalanx is dislocated back- 
 ward, or the metacarpal bone forward. When the collar is not torn, reduction is al- 
 most impossible, because the glenoid hgament is always interposed between the articular 
 surfaces. It should be remarked, that the metacarpo-phalangal articulation of the thumb 
 is the only one which is not capable of flexion backward. This is probably owing to 
 the want of looseness in its aaterior or capsular ligament. In this joint, the movement 
 of extension does not go beyond the straight line ; in this respect it resembles the ar- 
 ticulations which the phalanges form with each other.* 
 
 Adduction and abduction consist of simple latered glidings, limited by the meeting of 
 the other fingers. 
 
 Articulations of the Phalanges of the Fingers. 
 
 These are pulley-like joints, or perfect angular ginglymi. There are two articulations 
 of this kind in each finger, but only one in the thumb. 
 
 Articular Surfaces. — The lower end of the first phalanx, flattened from before back- 
 ward, presents a trochlea, broader on the pahnar than on the dorsal aspect, and prolonged 
 much farther in front than behind. The trochlea of the phalanx resembles the lower 
 end of the femur, with tjiis difference, that its two condyles are not separated from each 
 other. The upper end of the second phalanx, also flattened from before backward, pre- 
 sents two small glenoid cavities, separated by an antero-posterior ridge. The ridge cor- 
 responds to the groove of the pulley, and the glenoid cavities to the two condyles. 
 
 Means of Union. — 1. An anterior ligament {,y,fig. 74), grooved anteriorly, to serve the 
 tendon as a sheath, and exactly resembling what exists in the metacarpo-phalangal ar- 
 ticulations, and performing the same office of deepening the glenoid cavity, which by it- 
 self only imperfectly receives the pulley of the first phalanx. 2. Two lateral ligaments, 
 an internal {z) and an external {z'), arranged precisely in the same manner as the lateral 
 ligEiments of the metacarpo-phalangal articulations. They are attached to tubercles 
 situated behind the lateral depressions, on the lower end of the first phalanx, and pass 
 obliquely forward, to be inserted both into the glenoid ligament and the second phalanx. 
 There is no posterior ligament, its place being supplied by the extensor tendon. This 
 tendon is disposed in a peculiar manner : it gives off constantly a prolongation (w) from 
 its anterior aspect, which is inserted into the upper end of the second phalanx, so that 
 this bone presents a somewhat similar arrangement behind, as it does in front, with the 
 flexor tendon. This prolongation has a cartilaginous aspect. 
 
 The synovial capsule is precisely similar to that of the metacarpo-phalangal joints. 
 The foregoing description applies equally well to the articulation of the second with the 
 third phalanx. There is often a sesamoid bone in the substance of the glenoid ligament 
 of the two phalangal joints of the thumb. 
 
 Mechanism of the Phalanges. 
 The fingers are essentially the organs of prehension and of touch. In the mechanism 
 of touch, the fingers are moved over the surfaces of bodies, and are moulded upon even 
 their slightest inequalities, sometimes acting together, sometimes separately, seizing and 
 moving between them, as between the blades of sentient forceps, even the most delicate 
 objects. For the performance of this function, great mobility must be conjoined with 
 great precision of movement. On the other hand, for the purpose of seizing bodies, of 
 retaining, repulsing, or breaking them, as well as of acting as the means of attack and 
 defence, considerable power is required ; all which qualities are united in the mechanism 
 of the hand. Observe the number of the fingers and their complete isolation, so that 
 they can act either together or separately, and even in opposite directions. Notice the 
 number of the phalanges, their successive decrease in size, and the facility with which 
 they can be separated or made to approach each other, so as to be apphed around spher- 
 ical bodies. Note, also, the inequality of the fingers in length and power, enabling each 
 to act a determinate part in prehension ; and, above all, remark the shortness of the thumb, 
 which only reaches the base of the first phalanx of the index finger ; but which, placed 
 as it is upon a plane anterior to the rest, and endowed with a greater degree of mobili- 
 ty, can be opposed to all the fingers together, to each finger separately, and to every pha- 
 lanx of each, thus constituting the principal blade of the sentient forceps represented by 
 the hand ; for, being more strongly constructed, and provided with more powerful mus- 
 cles than the other fingers, it in some degree counterbalances them all. 
 
 * This is, I believe, the anatomical reason why a reduction of the dislocations forward of the n^tacarpo- 
 phalan^l articulations of the thumb and the other fingers is difficult, and sometimes impossible The most 
 skilful practitioners have sometimes failed in this reduction, and especially in dislocations of the thumb; ^n- 
 grene and death have often taken place in consequence of the violent attempts at reduction. I am certain that 
 the vertical section of the anterior ligament wotfld obviate the difficultj' at once. 
 
 u 
 
-'IM ARTHROLOGY. 
 
 .;' ... ^.rxbT^aXw^ Meckanism of the Phtdangal Articulations. 
 f^i From the shape of the articular surfaces, which form a miniatiire representation o£ 
 *the knee, it is evident that the only motions of which these joints are capable are flex- 
 ion and extension. The flexion of the second upon the first phalanx is as extensive as 
 it could possibly be, for it is only limited by the meeting of the anterior surfaces of these 
 bones. The amount oi flexion of the third phalanx upon the second is less considerable. 
 The extension of the second phalanx upon the first, and that of the third upon the second, 
 are limited, as in the metacarpo-phalangal joints, by the anterior glenoid and the lateral 
 ligaments. This motion of the phalanges is extremely slight ; I have never seen them 
 carried farther back than to form a straight line. 
 
 From what has been observed, it follows that, as regards its movements, each finger 
 'represents a shortened or miniature limb ; that, at its articulation with the metacarpus, 
 it is capable of motions in every direction, and also of circumduction ; that, from the 
 joints between the phalanges, it is endowed with the power of strong, extensive, and 
 accurate flexion ; and that, from the double bending of the second upon the first, and the 
 third upon the second phalanges, the fingers represent a true hook for seizing and cling 
 ing to external objects. 
 
 ARTICULATIONS OF THE INFERIOR OR ABDOMINAL EXTREMITIES. 
 
 Articulations of the Pelvis. — Coxo-femoral. — Knee-joint. — Peroneo-tibial. — Ankle-joint.— 
 Of the Tarsus. — Tarso-metatarsal. — Of the Toes. 
 
 Articulations of the Pelvis {figs. 76, 77). 
 The articulations of the pelvis are, 1. The sacro-iliac symphysis ; 2. The symphysis 
 pubis ; and, 3. The sacro-coccygeal articulation. The last has been already described with 
 the other articulations of the vertebral column. 
 
 Sacro-iliac Symphysis. 
 Preparation. — 1. Detach the pelvis from the rest of the trunk ; 2. Saw through the hor- 
 izontal ramus and arch of the pubes at the distance of about eighteen lines on each side 
 of the symphysis ; 3. Dislocate the os innominatum of one side ; 4. Dissect the anterior 
 ligaments of the sacro-iliac symphysis upon the other ; 5. Then make a horizontal section 
 of that articulation, dividing it into an upper and a lower half 
 The sacro-iliac articulation belongs to the class of symphyses or amphi-arthroses. 
 The articular surfaces are formed on the sacrum and os innominatum, and are partly 
 contiguous and partly continuous. The contiguous surfaces of these two boneS are an- 
 terior to the others, and are shaped like an ear, with the convex edge turned forward ; 
 hence they are called the auricular surfaces. The parts which are rendered continuous 
 by means of ligamentous fibres consist of the entire space comprised between the auric- 
 ular portion and the posterior border of the os innominatum, and of all the lateral sur- 
 face of the sacrum not occupied by the auricular facette. The continuous portions are 
 both marked with very rugged eminences and depressions. These articular surfaces are 
 also remarkable from being sinuous and alternately concave and convex, and from their 
 presenting a well-marked obliquity in two directions, viz., from above downward, and from 
 before backward and inward, so that the sacrum is, as it were, wedged between the ossa 
 innominata both in a vertical and an antero-posterior direction. 
 Means of Union. — The auricular surfaces are covered with cartilage, which is thicker 
 Fig. 76. upon the sacrum than on the os innominatum, 
 
 and is remarkable for the roughness of its 
 surface, which contrasts with the smooth ap- 
 pearance of other articular cartilages. There 
 is a distinct synovial membrane in this joint 
 in the infant and pregnant female, but it can 
 scarcely be detected in the adult and the 
 aged. The ligaments are, 1. An anterior sa- 
 cro-iliac ligament (b, figs. 76, 77), a very thin 
 layer which passes in front of this articula- 
 tion, and composed of fibres stretched trans- 
 versely from the sacrum to the ilium. 2. A 
 superior sacro-iliac ligament ii,fig- 52), a very 
 thick bundle, extending transversely from 
 the base of the sacrum to the contiguous 
 portion of the ilium. 3. An interosseous lig- 
 _^ ament, which forms the strongest bond of 
 
 onion in this joint, composed of a great number of ligamentous fibres, stretched horizon- 
 tally from the ilium to the sacrum, crossing each other, and filling up almost the whole of 
 the deep excavation comprised between the two bones ; these fibres leave small inter- 
 
ARTlCUL'A*'nroN^'^bF *rHE PELVIS. 155 
 
 vals between them, which are occupied by fat, and traversed by numerous small veins. 
 One of these bundles merits a special description : it consists of a long and strong band 
 extending almost vertically from the posterior superior spinous process of the ilium to a 
 thick tubercle on the third sacral vertebra ; it may be caUed the posterior vertical sacra-iliac 
 ligament. 4. The ilia-lumbar ligament {c,figs. 76, 77) maybe considered as belonging to 
 this joint ; it extends from the summit of the transverse process of the fifth lumbar ver- 
 tebra to the thickest part of the crest of the ilium, that is, to the enlargement situated 
 about two inches in front of the posterior superior iliac spine. It is a thick and very 
 strong triangular bundle. 
 
 Symphysis Pubis. 
 
 Preparatian. — This requires no special direction : only, in order to become acquainted 
 with the respective extent of the contiguous and continuous portions, it is necessary to 
 make two sections, a horizontal section, and also a vertical one from before backward. 
 
 The articular surfaces {e,fig. 77) are oval, having their longest diameters directed ver- 
 tically ; they are flat, and obliquely cut from behind forward and outward. Tliey are, 
 therefore, separated by a triangular interval, the base of which is directed forward, and 
 the apex backward. We should observe, concerning this articulation, that there are many 
 varieties in the respective extent of the contiguous and continuous portions of the artic- 
 ular surfaces. Sometimes they are almost wholly continuous ; at other times, on the 
 contrary, they are nearly altogether contiguous. I have observed this latter disposition 
 in a very remarkable degree in the symphysis of a young woman who died in the sixth 
 month of pregnancy. 
 
 The means ofuruon are the following : 1. Aii anterior pubic ligament {d,fig. 76), a very 
 thin fibrous layer, the posterior portion of which is blended with the interosseous liga- 
 , ment : it is composed of fibres extending from the spine of each os pubis obliquely to the 
 anterior surface of the opposite pubic bone ; those from the left side pass in front of those 
 from the right. 2. A posterior pubic ligament, extremely thin, and covering the prominence 
 formed by the ossa pubis behind, at the place of their articulation. This prominence, 
 which is very marked in old subjects, seems to be produced by a jutting out of the poste- 
 rior table of the bone backward, apparently caused by the pressure of one articular sur- 
 face upon the other ; these surfaces being, as we have described, in contact behind, but 
 separate in front. In a female who died of peritonitis soon after delivery, I found this 
 posterior prominence of the pubes fonning a sort of spine of some lines in diameter from 
 before backward. 3. A superior pubic ligament {e,fig. 76), very thick, and continuous on 
 each side, with a fibrous cord, that covers the upper edge of the os pubis, and effaces its 
 irregularities. 4. An inferior pubic or triangular ligament (/, fig. 76), which is exceed- 
 ingly strong ; it forms a continuation of the anterior and interosseous ligaments, and is 
 composed of interlacing fibres : this ligament renders the angle formed by the ossa pubis 
 obtuse, and gives to the arch of the pubes that regular curve presented by it to the head 
 of the foetus during labour. 5. An interosseous ligament (e, fig. 77), which occupies the 
 whole non-contiguous portion of the articular surfaces, and varies greatly in thickness in 
 different individuals. This hgament forms the principal means of union between the 
 bones of the pubes ; it fills up the vacant space of a line and a half to two lines, which 
 exists between the articular surfaces, and is composed of fibres, which cross each other 
 like those of the intervertebral substances.* 
 
 Of the Sub-pubic or Obturator Membrane, and the Sacro-sciatic Ligament. 
 We place the description of the obturator and sacro-sciatic ligaments next to that of 
 the articulations of the pelvis, simply remarking that they can scarcely be considered 
 true ligaments, but rather aponeuroses, which serve to complete the parietes of the pel- 
 vis, without contributing anything to the strength of the pelvic articijations. In trying 
 to account for the great obturator foramen and the great sciatic notch, I have asked my- 
 self the question whether these great openings, independently of their transmitting ves- 
 sels, nerves, and muscles, did not result from that law of osteology, by means of which 
 the bones, the levers of the muscular power, are formed with the least possible weight 
 and volume. How much heavier would the pelvis have been, if the obturator foramen 
 and the great sciatic notch had been filled with osseous tissue. It would have been use- 
 less, for the strength of the pelvis would not have been increased in any way by such an 
 arrangement. Perhaps these strong but flexible membranes are also useful during the 
 progress of labour, by diminishing the pressure of the soft parts of the mother between 
 the head of the child and the bones of the pelvis. 
 
 * From analogy, we may infer aa identical disjjosition in the pubic and vertebral symphysis. Thus it will be 
 seen that the articular surfaces in these two articulations are not fitted to each other. In the syniphyis pubis, 
 however, we discover an additional degree of mobility ; the articular surfaces are contiguous to a greater ex- 
 tent, and the synovial membrane is so perfect that no anatomist has yet doubted it. The symphysis pubis 
 might, therefore, be regarded as the transition between the movable aiticulations and the rai.ved or symphy- 
 ses. The obliquity in an inverse direction of the articular surfiices is the cause why the syraphysis pubis is 
 much larger in front than behind ; hence, in symphyseotomy or a section of the symphysis, the knife must be ap- 
 plied to the anterior portion of the symphysis, so tjiat the articulation may be entered into with more safety. 
 It is clear that a trocar could not be thrust into the bladder through the symphysis, on accojnt of Us bemj too 
 narrow behind to admit of its passage. 
 
166 ARTHROLOGY. 
 
 Sub-pubic or Obturator Membrane {g, figs. 76, 77). — This membrane closes the obtura- 
 tor (sub-pubic) foramen, excepting at its upper part, where we find a notch, by which the 
 groove for the obturator vessels and nerves is converted into a canal. The external 
 half of its circumference is attached to the corresponding margin of the obturator fora- 
 men, and the internal half to the posterior surface of the ascending ramus of the ischi- 
 um ; its two surfaces give attachment to the obturator muscles. The obturator mem- 
 brane is composed of aponeurotic bundles, which look like mother-of-pearl, and are in- 
 terlaced in every direction. An interesting point of its structure is its being formed of 
 several layers of fibres, and small bristle-shaped collections of fibres arising constantly 
 from the internal half of the margin of the obturator foramen, which expand upon the 
 anterior surface of the membrane, and afterward intermingle with the periosteum. 
 There is also to be found a very strong parcel arising from a sort of spine upon the mar- 
 gin of the obturator foramen, immediately above the level of the great cotylo d notch. 
 
 Sacro-sciatic Ligaments. — These are divided into the great and the S7nah . ^'e apply 
 the term ligaments to them rather on account of their fasciculated shape than fron» their 
 use, which scarcely has reference to the union of the bones of the pelvis. 
 
 The great sacro-sciatic ligament {I, figs. 76, 77) arises from a ridge situated on the in- 
 ternal hp of the tuberosity of the ischium, and also from the ascending ramus of the 
 same bone, by a curved margin of considerable extent, having its concavity directed up- 
 ward, which, with the inner surface of the tuberosity of the bone, forms a groove for the 
 protection of the internal pubic vessels and nerves. The most superficial fibres of this 
 ligament are partly continuous with the common tendon of the biceps and the semi-ten- 
 dinosus. Immediately after its origin, from its fibres being collected together, it be- 
 comes very narrow and thick, and is directed upward and inward ; it then expands con- 
 siderably, and is inserted into the edges of the sacrum and coccyx, and more slightly 
 into the posterior part of the crest of the ilium, as far as the posterior and superior spi- 
 nous process of this bone. Its upper edge, or, rather, its external, is vertical, and is 
 continuous with the aponeurosis, extending over the pyriformis muscle. Its internal 
 edge, which forms a curve, and which is almost horizontal, makes part of the inferior 
 circumference of the small pelvis ; it fines the small sacro-sciatic ligament, to which it 
 adheres at its insertion into the coccyx, and from which it is separated externally by a 
 triangular space, where it is in relation with the internal obturator muscle ; it is covered 
 by the gluteus maximus, to which it furnishes a great number of aponeurotic insertions. 
 This disposition increases the thickness of this ligament considerably, and gives to its 
 posterior surface the rugged, rough, and, as it were, lacerated aspect, which is a char- 
 acteristic of that surface. The great sacro-sciatic ligament is composed of bundles, sev- 
 eral of which, on a level with the narrowest portion of this ligament, are interlaced in 
 the shape of the letter X. Several of these ligaments, which are external at their sci- 
 atic insertion, become internal at their insertion into the coccyx, and vice versa. The 
 great sacro-sciatic ligament and the posterior and superior sacro-iliac ligaments consti- 
 tute a fibrous plane in the shape of bundles, arising from the superior posterior spinous 
 process of the ilium, and extending in various directions. 
 
 fVg.. 77, The small sacro-sciatic ligament {m,figs. 76, 77), placed in 
 
 front of the preceding, and extremely thin, arises from the 
 summit of the spine of the ischiimi, passes inward, and, 
 becoming thinner, is lost upon the anterior surface of the 
 great sacro-sciatic ligament. The two sacro-sciatic liga- 
 ments divide the great sacro-sciatic notch into two distinct 
 foramina : the upper (n, fig. 77) is very large, and shaped 
 like a triangle with the angles rounded off, and is in a great 
 measure filled up by the coccygeus and pyriformis muscles ; 
 it gives passage also to the great and small sciatic nerves, 
 to the ischiatic vessels, and to the gluteal and internal pu- 
 dic vessels and nerves, and to a large quantity of cellular 
 tissue. That form of hernia which is called sciatic takes 
 place through this foramen. The lower {o,fig. 77) is much 
 smaller ; it is situated between the spine and tuberosity of 
 the ischium, and gives passage to the obturator intemus 
 muscle, and to the internal pudic vessels and nerves. 
 
 Mechanism of the Pelvis. 
 
 The mechanism of the pelvis should be regarded in four distinct points of view : 1. 
 As affording protection to the contained viscera ; 2. In relation to the part which it per- 
 forms in the mechanism of standing and progression ; 3. In connexion with the phenom 
 ena of part mtion ; and, 4. In reference to the motions which take place at its articula 
 tions with other bones, and those between its own component parts. 
 
 I. Mechanism of the Pelvis considered as a Protecting Structure. — The following are the 
 conditions in the structure of the pelvis, having reference to its ofiice as a protector of 
 the contained viscera : 1. Behind ; the presence of the sacrum, which is itself pi-otected. 
 
ARTICULATIONS OP THE PELVIS. ISV 
 
 as well as the nerves that pass through it, by the great prominence of the posterior iliao 
 tuberosities, which project considerably beyond it ; 2. On the sides, by the crest of the 
 ilium, and the prominence of the trochanters, which so often preserve the pelvis from ex- 
 ternal violence. With regard to the large notch in front, which leaves the viscera situ- 
 ated on a level with it, unprotected, it may be remarked, that the viscera contained in the 
 small pelvis, being liable to considerable changes of volume, require to leave the osseous 
 and unyielding space which contains them when empty, in order that they may extend 
 into a cavity the walls of which are soft, and may be dilated almost indefinitely ; 3. In 
 front the means of protection are much less efficacious, in consequence of the vast notch 
 which is situated in this region. 
 
 The partial absence of the bony parietes in front has reference to the great variation? 
 in size which the viscera of the pelvis can undergo, and which would have been incom- 
 patible with the existence of an osseous cincture, incapable of dilatation. The absence 
 of bony walls in the situation of the three great notches, presented by the outlet of the 
 pelvis, is also unfavourable to its solidity ; but it has many other important uses, partic- 
 ularly in the mechanism of labour. The pelvis, especially at its upper part, where it is 
 most exposed to injury, is enabled to resist external violence by virtue of its vaulted con 
 struction. Part of the impulse, also, is lost in producing the slight degree of gliding mo 
 tion permitted at the symphysis pubis. "Where, however, the power of resistance pos- 
 sessed by the pelvis is overcome, it will be seen at once that the parts most liable to 
 fracture are the ascending rami of the ischia at their junction with the descending rami 
 of the ossa pubis. 
 
 2. Mechanism of the Pelvis with regard to Standing and Progression. — The part perform- 
 ed by the pelvis in standing is connected with the transmission of the weight of tlie trunk 
 to the lower extremities ; this is efFi>cted by means of "the sacrum, which rests upon the 
 ossa innominata. We should add, that a small portion of the weight is directly trans- 
 mitted to the femurs by the iliac bones, which support the viscera of the abdomen. 
 
 TQbe following arrangements should be noted, as being concerned in the transmission of 
 the weight by means of the sacrum : 1. The great size of that bone, affording evidence 
 of the destination of man for the erect posture. 2. The obtuse angle at which the sacrum 
 unites with the vertebral column, peculiar to the human species, and which becomes the 
 seat of a decomposition of the force transmitted by the spine. Part of the momentum 
 acting in the direction of the axis of the column has no other effect than that of increas- 
 ing the sacro- vertebral angle, at the expense of the flexibility of the inter-articular car- 
 tilage ; the rest is transmitted to the sacrum, and then to the lower extremities. 3. The 
 double wedge shape of the sacrum itself. In order to understand the advantage arising 
 from this form, it is necessary to remark, first, that the weight of the trunk is transmit- 
 ted in the axis of the upper half of the sacrum, and, consequently, in the direction of a 
 line sloping downward and backward ; from this it follows, that the sacrum must have 
 a tendency to be displaced either downward or backward, but the displacement downr 
 ward is prevented by the position of the ossa innominata, which are nearer to each other 
 below than above. The displacement backward is obviated by the oblique direction of 
 the articular surfaces of the same bones backward and inward, while the obliquity of the 
 sacrum itself is in the opposite direction, for it is broader in front than behind.* 4. The 
 distance intervening between the sacro-iliac and the coxo-femoral articulations. The 
 articulation of the vertebral column with the pelvis being situated at the back part of that 
 cavity, while those of the femurs are situated towards the front and the side, the distance 
 between them increases the space in which the centre of gravity can oscillate, without 
 being carried so far forward as to pass beyond the perpendicular let fall from the coxo- 
 femoral articulation to the base of support. In man alone is found a large pelvian basis 
 of support, and thus the erect posture has been rendered possible in him, without an ex- 
 cessive extension in front. 
 
 In quadrupeds, the antero-posterior diameter of the bones of the ilium is rather short, 
 and their haunch bones are elongated behind, and placed in almost the same plane as 
 the vertebral column. The foetus and new-born infant somewhat resemble the lower 
 animals in this respect, and, therefore, in the human subject there is a great tendency 
 to assume the attitude of a quadruped during the first year of existence. 
 
 The weight received by the sacrum and transmitted to the haunch bones is divided, 
 sometimes equally and sometimes unequally, between the sacro-iliac symphyses. One 
 portion of the impulse calls into action the mobility of the symphyses, and the remainder 
 is transmitted to the cotyloid cavities. It should be remarked, that this transmission is 
 effected along the triangular prismatic columns, which form the sides of the inlet of the 
 pelvis, and are the thickest and strongest parts of that structure. At the foot oi these 
 
 * Without admitting- that the influences to which the sacrum is subjected have a tendency to force it back- 
 ward as well as downward, it is impossible to explain either the use of its being- shaped like a wedge, with 
 the base turned forward, or of that powerful apparatus of posterior ligaments which can oidy resist its disloca- 
 tion backward. The idea that these forces tend to press it forward is manifestly at variance with the naturt 
 of the uniting media ; for the sacro-iliac symphyses are only maintained in front by a very thin ligamentous 
 layer, and the breadth of the space between the iliac bones is also greater in front than behind; ciicumstaa- 
 ces that ■\\ould evidently facilitate displacement forward. 
 
ARTHROLOGY. 
 
 columns, which form cmres, we find, dug, as it were, into their substances, the cotyloid 
 cavities, to which the weight of the trunk is transmitted. During the sitting posture, the 
 weight of the body is transmitted to the tuberosities of the ischia, which, from their great 
 size, are well fitted to support it. As these processes are a little anterior to the cotyloid 
 cavities, and, therefore, situated in a plane very near the front of the pelvis, the centre 
 of gravity of the trunk has a tendency to fall behind the basis of support represented by 
 them ; and, therefore, it is easy to push an individual backward when in the sitting pos- 
 ture, inasmuch as in front the basis for the support of the pelvis is increased by the length 
 of tlie femurs and the length of the foot while man is seated on a chair, and the whole 
 length of the abdominal extremity while he is seated on a horizontal plane. The mode 
 in which the pelvis resists violence appUed to the tuberosities of the ischia in falls, is some- 
 what connected with its mechanism as adapted to the sitting posture. The shock is, in 
 these cases, transmitted directly upward in the dh-ection of the acetabula, the lower hem- 
 ispheres of which offer resistance like two arches : from the acetabula the impulse is 
 communicated backward, by the thick columns extending from behind these cavities, to 
 the sacro-iliac symphyses ; and forward, to the symphysis pubis ; so that falls upon the 
 tuberosities are dmost always accompanied with painful concussion both of the sacro- 
 iliac and pubic symphyses. 
 
 In order to complete our account of the mechanism of the pelvis in standing, we must 
 examine its mode of resistance in falls upon the knees or soles of the feet. In this case, 
 the shock is communicated from below upward to the upper halves of the cotyloid cavi- 
 ties, wliich are supported by the prismatic columns already described. The anterior 
 part of each acetabulum presents a large notch, and is altogether unconcerned in the 
 transmission of these shocks ; so, also, is the very thin lamina constituting the bottom or 
 inner wall of the cavity, which can only suffer compression in falls upon the great tro- 
 chanter. The great difference existing between a fall upon the knees and the tuberosi- 
 ties of the ischia, and the fall upon the points of the feet, with regard to a commotion of 
 the brain and the spinal marrow, may be easily conceived. While standing on one 4»ot 
 the weight of the trunk is transmitted to the femur by the sacro-iliac symphyses, and by 
 the curve-shaped column of the side which bears upon the ground. In this position a 
 fall readily takes place, on account of the facihty with which the centre of gravity passes 
 the basis of support. 
 
 During progression, the pelvis affords to each thigh alternately a solid fulcrum, and re- 
 ceives itself a fixed point of support from the femur of that leg which rests upon the 
 ground. While onp side of the pelvis is thus supported upon one of the thigh bones, the 
 other side is projected forward. These alternate movements of projection of either side 
 of the pelvis take place at the coxo-femoral articulation of the extremity which rests 
 upon the ground. The alternate movements of projection increase in proportion to the 
 breadth of the pelvis. It is for this reason that women, in walking, move the hips more 
 than men. The remark of a witty author, that " running is the only thing which women 
 are unable to do gracefully," is an allusion to this rather awkward motion of the pelvis. 
 We may form a correct idea of the share which the pelvis takes in the act of walking by 
 studying the mode of progression of persons with wooden legs. In these unfortunate 
 beings the lateral inclinations of the pelvis are sufficient for progression by transporting 
 the centre of gravity alternately to the two inflexible columns substituted for the lower 
 extremities. 
 
 3. Mechanism of the Pelvis with regard to Parturition. — The art of midwifery depends, 
 in a great measure, upon the study of the pelvis ; it is impossible to form a true concep- 
 tion of the mechanism of natural labour without being acquainted with the axes of the 
 pelvis, its dimensions as compared with the size of the foetus, the sacro- vertebral angle, 
 the inclined planes of the true pelvis, the diameters of the brim and the outlet, and the 
 malformations to which it is liable. Any lengthened details upon these points would be 
 out of place here. I shall only remark, I. That the existence of the arch of the pubes 
 is pecidiar to the human species ; and, 2. That the sciatic notches and the obturator 
 foramina are not only useful from economizing weight, but also because, corresponding 
 as they do to the oblique diameters of the head of the foetus during parturition, they ren- 
 der less painful the pressure attendant upon that process ; 3. That the pyramidales, the 
 mtemal obturators, and the psoae and iliaci muscles perform, so to speak, the office of mat- 
 tresses in the pelvic cavity ; 4. That parturition, consisting in the expulsion of the foetus 
 along the line of the pelvis, natural parturition, provided the expulsive power exists in 
 its normal conditions, depends partly on a true conformation of the pelvis, and partly on 
 a true conformation and position of the foetus ; 5. That a general idea of all the defects 
 which may occur in the conformation of the pelvis may be expressed by stating, that 
 this cavity is liable to all the malformations which may result from a pressure upon its 
 whole brim or only a part of it, from above downward, from below upward, from before 
 backward, or from side to side. 
 
 4. Mechanism of the Pelvis with regard to its own Movements. — The intrinsic movements 
 of the pelvis are very obscure, being confined to mere gliding or swinging motions, the 
 production of which destroys part of the momentum from any external violence. By 
 
COXO-FEMOEAL AETICULATION. 159i 
 
 some admirable contrivance, the mobility of the intrinsic articulations of the pelvis is 
 considerably increased during the latter periods of pregnancy, so that the coccyx may be 
 pressed backward, causing an increase of five or six lines in the antero-posterior diam- 
 eter of the outlet ; wliile the symphysis pubis* becomes susceptible of a slight separa- 
 tion, which increases (in a very slight degree, it is true, but sufficiently to merit notice) 
 the dimensions of the brim of this cavity. This mobiUty, which is especially remarkable 
 in a narrow pelvis, favours the process of labour in a singular degree. The natural mobil- 
 ity of the symphysis pubis has suggested the operation of symphyseotomy, by which the 
 diameters of the pelvis, however, are but little increased, unless the severing of the 
 bones of the pubes should be carried far enough to result in a separation of the sacro- 
 iliac symphysis. A relaxation taking place in the symphysis of the pelvis may give rise 
 to strange errors in diagnosis. 
 
 The extrinsic movements of the pelvis are those of flexion, extension, lateral inclina- 
 tion, and rotation : these motions, which are all very hmited, have been indicated in 
 describing the mechanism of the vertebral column. The motions of the pelvis upon the 
 thighs are very considerable : they will be examined with the mechanism of the hip-joint. 
 
 CoxO-FEMOEAL ARTICULATION {fig. 76). 
 
 Preparation. — Remove with care all the muscles that surround the joint, preserving 
 the reflected tendon of the rectus femoris. The psoas and iliacus muscles, the synovial 
 capsule of which so often communicates with the articular synovial membrane, must be 
 removed with particular care. After the fibrous capsule has been studied upon its exter- 
 nal surface, a circular division should be made round its middle portion, for the purpose 
 of uncovering the deep-situated parts. This articulation is the type of the order enar- 
 throsis, being a true ball and socket joint. 
 
 The articular surfaces are the globular head of the femur, and the cotyloid cavity of the 
 OS innominatum. There is a striking difference between this joint and that of the shoul- 
 der, as far as regards the size of the articular head and the depth of the articular cavity. 
 While the head of the humerus and the glenoid cavity are simply in juxtaposition with- 
 out any reception of the former into the latter, so that the scapulo-humeral articulation 
 has for a long time been, and is now considered as an arthrodia, there is a deep and com- 
 plete fitting of the head of the femur into the cotyloid cavity, which we have pronoun- 
 ced to be the deepest articular cavity of the body. Both of the surfaces above named 
 are covered with cartilage, with the exception of two depressions, one of which is situa- 
 ted on the head of the femur, the other at the bottom of the cotyloid cavity : the latter 
 is filled with a reddish adipose tissue, improperly called the cotyloid gland. It is analo- 
 gous to the adipose tissue found in the neighbourhood of all the joints ; its use is not 
 well known. I have often asked myself the question, Why should there be this poste- 
 rior cotyloid cavity ! On submitting the joint to an antero-posterior vertical section, 
 shghtly encroaching on the margin of the posterior cotyloid cavity, it will be seen that 
 the object of this cavity is to protect the round ligament in all the possible positions of 
 the head of the femur ; and that, without this cavity, the round ligament could not have 
 existed \vithout its being compressed between the articular surfaces. Now, as the intra- 
 articular vessels enter this cavity, and go to the head of the femur along the round lig- 
 ament, it is not impossible but that the exclusive use of this posterior cotyloid cavity 
 should be to protect the vessels destined to the head of the femur, and that the round 
 hgament itself should have no other use than to support these vessels, and to transmit 
 them to the head of the femur. The cotyloid adipose tissue does not seem to have any 
 other object, except to fill the empty space of this posterior cavity. 
 
 It appears to me that the round ligament of the coxo-femoral articulation of the poste- 
 rior cotyloid cavity serves the same purpose as the space between the condyles of the 
 lower end of the femur and the crucial ligaments of the knee-joint. 
 
 Means of Union. — The cotyloid ligament {n, fig. 76). This band, improperly called co- 
 tyloid ligament, is attached to the margin of the acetabulum, which it, as it were, com- 
 pletes ; it augments the depth of the cavity, and renders smooth its sinuous and notched 
 circumference. It is of greater size at the notches than in any other part : by its means 
 the irregularities of the edge of the acetabulum are effaced, and the deep- notch in front 
 and below is converted into a foramen for the passage of vessels to the fatty tissue, the 
 inter-artiailar ligament, and the head of the femur. 
 
 The cotyloid band is much thicker above and behind than below and in front, and it 
 is precisely against the first two points that the head of the femur constantly presses. 
 It is also remarkable, in this respect, that the diameter of its free borders is smaller than 
 that by which it is attached ; and this circumstance assists, in some degree, in retaining 
 the head of the femur in the cotyloid cavity, t It consists of fibres which arise succes- 
 
 * In a female seventy-nine years of age, the mother of nineteen children, I found the symphysis pubis ex- 
 tremely movable : the two articular surfaces of the pubes were contiguous ; the interosseous ligament had 
 disappeared ; and a very thick, fibrous capsule, of recent formation, surrounded the articular surfaces in front, 
 above and below, being inserted at some distance from them. It was a symphysis changed to a loose arthrodia. 
 
 t I have never seen this disposition better exhibited than in a subject in which the cotyloid band was OSM- 
 fied in its whole extent, except at the place on a level with the anterior and inferior notch. The head of thfl 
 
160 ARTHROLOGY. 
 
 sively from all points of the circumference of the acetabulum, and interlace at very acute 
 angles. This interlacement is especially visible in the situation of tlie great anterior 
 notch, where the fibres may be seen arising from each side of the notch, and passing 
 across each other. 
 
 The orUcular ligament, or Jibrous capsule (p, Jig. 76). This represents a fibrous sac, 
 having two openings, by one of which it embraces the acetabulum, outside the cotyloid 
 ligament, while the other surrounds the neck of the femur. The femoral insertion of 
 the capsular ligament requires to be carefully studied, for the purpose of explaining the 
 difference between fractures within, and fractures beyond, the capsule. This insertion 
 is so arranged, that at the upper part and in front of the joint it corresponds with the 
 base of the neck of the femur, while beneath and behind it is situated at the junction of 
 the external wich the two internal thirds of the neck. The insertion of the capsule in 
 front takes place not only at the base of the neck of the femur, but also internally to this 
 base, to the extent of several lines, as may be ascertained by an incision being made 
 along this insertion in the direction of the axis of the neck. The length of tlie orbicular 
 ligament is exactly equal to the distance between its insertions, excepting at the inner 
 part, where it is much more loose. Hence the extent of the motion of abduction, which 
 is so remarkable in some jugglers, that they are able to separate their legs until they 
 form right angles with the body, without producing dislocation. 
 
 The thickness of this ligament is not equal throughout : it is greatest above and on 
 the outside, where the reflected tendon of the rectus muscle is situated ; it is yet very 
 considerable in front and above ; it is less thick behind, and still thinner on the inside. 
 In some subjects the thickness of the superior part of the capsule is to that of the inferi- 
 or as five to one. In front, the capsule is strengthened by a bundle of fibres stretched 
 Dbliquely, like a sling, from the anterior inferior spinous process of the ilium to the inside 
 of the base of the neck of the femur. It is called by Bertin the anterior and superior lig- 
 ament (r, fig. 76). This band, which serves as a re-enforcement to the capsule, lies un- 
 der that portion of the iliacus muscle which arises from the anterior spinous process of 
 the ilium, and follows the direction of this muscle ; it is composed of pardlel fibres, and 
 closely adheres to the capsule, without adhering in the least to the muscle. Within this 
 bundle the capsule is often imperfect, and permits a communication between the synovial 
 membrane of the joint and the bursa of the psoas and iliacus muscles. This last syno- 
 vial membrane may be considered as a prolongation of the articular synovial membrane ; 
 this prolongation is analogous to the one which we have described at the scapulo-hume- 
 ral articulation for the subscapularis muscle. In one subject that I dissected, the com- 
 municating orifice was so large, that the common tendon of these muscles was in imme- 
 diate contact with a considerable portion of the head ofthe femur ; the tendon itself be- 
 ing split into several bands, some of which had been lacerated, and, as it were, worn 
 away by friction. 
 
 The external surface of the capsular ligament is in relation with the psoas and iliacus 
 muscles in front, being separated from them by a bursa at the upper part, in those cases 
 where the fibrous capsule is not interrupted, and giving insertion to many of their fibres 
 below. On the inside, it is in relation with the obturator externus and the pectineus ; 
 on the outside, with the gluteus minimus ; behind, with the quadratus femoris, the ge- 
 melli, the pyi-iformis, and the obturator intemus. Several of these muscles send fortify- 
 ing bundles of fibres to the capsule. I may point out an aponeurotic expansion coming 
 from the gluteus minimus, which establishes a close connexion between this muscle and 
 the capsule ; a second expansion, furnished by the pyriformis and the gemelli ; and a third, 
 which is furnished to the capsule by the tendon of the vastus externus. The internal 
 surface is lined by the synovial membrane. 
 
 The orbicular ligament ofthe hip-joint differs from the generality of such structures 
 in being of a dull white instead of a pearly white colour, and in being composed of ir- 
 regularly interlaced fibres, except the superficial fibres, which are disposed in parallel 
 lines. I have also observed a very remarkable fact, apparently overlooked by anatomists, 
 viz., that it is extremely thin at its inferior orifice, but especially behind ; and that near 
 this insertion it is strengthened by some circular fibres which embrace the neck of the 
 bone like a collar, but without adhering to it ; and that in its different movements this 
 sort of collar rolls round the neck, but is retained in its place by small bundles of fibres, 
 reflected from the capsule upon the neck of the bone, which raise the synovial mem- 
 brane from the surface. 
 
 The intcr-articular, which is improperly called round ligament (t, fig. 76). This ligament 
 arises, under the form of a fibrous band, folded backward upon itself, from the depression 
 on the head of the femur, which depression is not entirely filled by it. It is twisted 
 around this head, and is divided into three bands, one of which, after having again been 
 subdivided, traverses the adipose tissue and is fixed into the bottom of the cotyloid cav- 
 ity, while the two others are attached to the two edges ofthe cotyloid notch, below the 
 cotyloid band, by which this insertion, with which it is often continuous, is concealed. 
 
 femur wis mechanically and solidly retained in the acetabulum, whose bottom, being partly worn out ani] 
 pressed inward, fonned a prominence in the interior face of the pelvis. 
 
COXO-FEMORAL ARTICULATION. 161 
 
 In one case a prolongation of this ligament traversed the cotyloid notch, and was at- 
 tached to the part nearest the capsule. The thickness and the strength of this inter-ar 
 ticular ligament are extremely variable : sometimes it is extremely strong, sometimes very 
 weak ; sometimes it adheres to one edge only of the notch ; sometimes it consists mere- 
 ly of a few ligamentous fibres, contained within the substance of the reflected synovial 
 membrane ; sometimes in its place is found a fold of that membrane, which may be torn 
 by the slightest force ; and, lastly, it is not uncommon to find that it is altogether wanting. 
 The synovial membrane lines the whole internal surface of the capsular ligament the 
 two non-adhering surfaces of the cotyloid ligament, and that part of the neck of the fe- 
 mur contained within the joint ; it embraces the round ligament, and sends off a pro- 
 longation from it to a quantity of fatty matter at the bottom of the acetabulum;* an ar- 
 rangement which led the older anatomists to believe that the round ligament was in- 
 serted into the bottom of the cotyloid cavity. 
 
 Mechanism, of the Coxo-femoral Articulation. 
 
 Like all enarthroses, the coxo-femoral articulation can execute movements of flexion, 
 extension, abduction, adduction, circumduction, and rotation. 
 
 1. Inflexion, the head of the femur roUs in the cotyloid cavity around an imaginary 
 axis corresponding with that of the neck of the bone, while the lower end of the femur 
 is carried from behind forward, and describes the segment of a circle, whose radius is 
 represented by the shaft of the bone. In the mechanism of this movement, the neck of 
 the femur has the effect of substituting a rotatory motion of the head of that bone upon 
 a fixed point, without changing the relation of the head with the acetabulum, and, con- 
 sequently, without any tendency to displacement, for a very extensive movement back- 
 ward and forward, which would otherwise have been necessary, and in which the sur- 
 faces would have been liable to separation from each other. We can, indeed, scarcely 
 believe that luxation would be possible during this motion, although it can be carried so 
 far that the front of the thigh and the fore part of the abdomen may be brought in contact 
 
 2. Extension is effected by the same mechanism, the head and the neck of the femur 
 rolling upon themselves from behind forward, while large arcs of a circle, from before 
 backward, are described by the body of the bone ; but such is the obliquity of the acetab- 
 ulum, which looks both forward, outward, and downward, that when the femur is in the 
 vertical direction, the head projects and carries forward the fibrous capsule. The anterior 
 re-enforcing bundle is stretched. The psoas and iliacus muscles perform the office of an 
 active ligament. Luxations of the femur forward are not common, for the movement of 
 extension is limited by the meeting of the edge of the acetabulum and the back part of the 
 neck of the femur ; and the ligament and muscles above named also tend to counteract it. 
 
 3 and 4. The mechanism of adduction and abduction is altogether different from that 
 of the preceding movements, where the articulation forms the centre of a circle descri- 
 bed by the femur, the radius of which is measured by a line stretched from the head of 
 the bone to the space between the condyles. In abduction, the head of the femur presses 
 against the inner part of the capsular ligament ; and, on account of the looseness of this 
 ligament, the obliquity of the acetabulum, and the arrangement of the inter-articular lig- 
 ament, this movement may be carried very far without displacement, and is only limited 
 by the meeting of the upper edge of the neck of the femur with the rim of the cotyloid 
 cavity. But this very niceting may itself become the cause of luxation, and then the 
 edge of the cotyloid cavity may be regarded as the fulcrum of a lever of the first order 
 with unequal arms, the whole length of the femur being the arm, to which the power is 
 applied, and the neck of the bone, that by which the resistance acts. 
 
 In adduction, the femur moves in precisely the opposite direction : this motion is lim- 
 ited by the mutual contact of the two thighs, but, by means of slight flexion, it may be 
 carried so far as to throw one over the other. The great depth of the upper and exter- 
 nal part of the cotyloid cavity, and the strength of the capsular ligament in the same di- 
 rections, would seem to oppose all displacement. But it should be observed, that falls 
 upon the knees almost always happen during adduction of the thighs, for this is an in- 
 stinctive movement of preservation. However slight the adduction may be, the inter- 
 articular ligament is of necessity stretched ; and from this it follows, as my colleague, 
 M. Gerdy, has ingeniously remarked, that the head of the femur is detached from the 
 bottom of the cavity by a kind of rolling of the round ligament upon it, and comes to 
 press against the fibrous capsule. The rupture of the inter-articular ligament is not al- 
 ways necessary in luxation. I have seen several instances of a so-called incomplete lux- 
 ation inward, without this hgament being torn. 
 
 5. Circumduction consists in the transition from one of these motions to another. The 
 
 * The synovial membrane is often seen, being interposed and descending- between the adipose substance 
 and the posterior cotyloid cavity. I may also point out semilunar folds, which are often formed by tne syno 
 rial membrane round the neck of the femur. These folds are supported by some detached fibres of the cap- 
 Bule, so that the neck, on a level with those fibres, is lined with synovial membrane only in the neighbour 
 hood of the head of the femur. The synovial folds appear to me destined to conduct vessels to the margin of 
 the head of the femur. Round the head of the femur, at its point of union with the neck, are constants 
 found very small adipose bundles. v • - • • 
 
 X 
 
162 ' "' ' ■ ARTHROLOGY. 
 
 femur circumscribes a cone, of which the apex is in the joint, while the base is described 
 by the lower end of that bone. The axis of the cone is represented by aline drawn 
 from the head of the femur to the interval between the condyles ; and the length of the 
 femur accounts for movements which are scarcely felt at the coxo-femoral articulation, 
 being so considerable at the lower end of the bone. 
 
 6. Independently of the movements above described, the coxo-femoral articulation per- 
 forms motions of rotation, arising by no means from its enarthrodial shape, but from the 
 presence of the neck of the femur. Generally no movement appears to require a greater 
 expenditure of power on the part of nature than the rotatory movements, and these move- 
 ments are not always regulated by the same mechanism. We have already seen an ex- 
 ample of this movement in the atlo-axoidian articulation, where a cylinder forme 1 by tho 
 odontoid process rolls in the partly osseous and partly fibrous ring of the atlas, as an axle 
 tree in a wheel. Here the arrangement is quite different ; the rotatory movement is ob 
 tained simply by the lever being bent like an elbow in such a manner as to make the rota 
 tory movements of the femur upon its axis result from the movements forward or backward 
 of the bent portion. This movement should be studied both at the upper and at the lower 
 part of the femur. At the upper part it is a motion of horizontal displacement, the radi- 
 us being represented by the head and neck of the bone ; at the lower part it is a rotatory 
 motion of the femur, not precisely upon itself, but upon an imaginary axis placed on the 
 inside of, and parallel to, the shaft. It follows that there can be no rotation in cases of 
 fracture of the neck of the bone, and this is one of the diagnostic signs of that accident 
 Lastly, it may be observed that rotation is perfonned from without inward, or from within 
 outward : the latter is the more extensive and more natural movement ; it is produced by 
 a great number of muscles, and, therefore, during repose, the point of the foot is slightly 
 inclined outward. 
 
 The Knee-joint (Jigs. 78 to 81). 
 Preparation. — 1. Make a crucied incision in front of the knee and dissect back the flaps. 
 
 2. Detach the aponeurosis of the thigh, preserving the fibrous band, which forms the con- 
 tinuation of the tensor vagina femoris, and which forms, as it were, a superficial ligament. 
 
 3. Remove the aponeurosis of the triceps on the sides of the patella, taking care to avoid 
 opening the synovial capsule. 4. Remove the tendon of the biceps, and turn downward 
 the tendons of the sartorius, gracilis, and semitendinosus. 5. Remove the popliteal ves- 
 sels and nerves behind, and also the gastrocnemii. 6. After having studied the ligaments 
 situated around the synovial capsule, isolate the latter as much as possible by dissecting 
 off the lateral ligaments, and the ligamentum patellae. 7. Open the synovial capsule 
 above the palate. 8. Make a horizontal section of the femur immediately above the con- 
 dyles, and a vertical section from before backward between the condyles These two 
 sections are intended to expose the crucial ligaments. 
 
 The articulation of the knee belongs to the class of angular ginglymi ; it is the largest 
 and most complicated joint in the human body ; it is, perhaps, the most important, both 
 in regard to the part which it plays in the mechanism of the animal economy, and the fre- 
 quency and the gravity of the maladies which it is liable to. 
 
 Articular Surfaces. — The lower end of the femur and the upper end of the tibia are the 
 essential constituents of this joint, which is completed in front by the patella. The ar- 
 ticular surface of the femur is formed in front by the trochlea, and behind by the two 
 condyles, separated by the intercondyloid fossa ; the articular surface of the tibia con- 
 sists of the glenoid cavities, separated by the spine of the til)ia, in front of and behind 
 which are some irregular projections. The patella presents two concave surfaces, sep- 
 arated from each other by a vertical ridge corresponding to the groove of the trochlea. 
 These surfaces are aU covered with a thick layer of cartilage. It should be remarked, 
 with regard to the knee-joint, 1. That the articular surfaces are rather placed in juxta- 
 position than jointed together ; 2. That the articulation is in some measure double, since 
 two very distinct condyles correspond to two equally distinct cavities. These two con- 
 dyles being turned in opposite directions, viz., the external backward and outward, the 
 internal backward and inward, they are opposed to each other ; like the articulation oi 
 the two condyles of the occipital bone with the atlas, which are opposed both to the lat- 
 eral and the rotatory motions, and, in regard to these motions, constitutes an angulai 
 ginglymus, so in the case in the knee, its two condyles constituting, as it were, a double 
 condylian articulation, transformed into an angular ginglymus. 
 
 Inter-articular Cartilages. — Like all joints that are exposed to much pressure, the knee 
 is provided with inter-articular cartilages. They are two in number, and are named, 
 from their figure, semilunar or falciform cartilages (a, b, fig. 78). Their upper surfaces, 
 corresponding to the convexity of the condyles, are concave ; their external circumfer- 
 ence is very thick, and the internal sharp and thin : they therefore assist in deepening 
 the concave surfaces of the tibia. The section of tlicse cartilages forms an elongated 
 isoscele triangle, with its base outward. The external inter-articular cartilage (a) gov 
 ers almost the whole of the external glenoid cavity of the tibia, fonning nearly a com- 
 plete circle ; while the internal cartilage (4), which is, indeed, semilunar, leaves a great 
 
ARTICULATIONS OP THE KNEE-JOINT. 
 
 '-.H^'UnMt* . 
 
 1^.78. 
 
 part of the corresponding cavity uncovered.* In this respect 
 the inter-articular cartilages of the knee differ from all others 
 of the S2uiie kind, for they do not establish a complete separ- 
 ation of the articular surfaces, between which they are placed. 
 « hese falciform cartilages are inserted into the tibia by means 
 of ligaments, which deserve a particular description. 
 
 Ligaments of the External Semilunar Cartilage. — These are 
 two : the one anterior, and the other posterior ; both of them 
 are very strong. The anterior is inserted in front of the spine 
 of the tibia, outside of the anterior crucial ligament, into a 
 deep depression situated near the external glenoid cavity of 
 the tibia. This anterior ligament of the external semilunar 
 cartilage sends off a bundle which intermingles with the ante- 
 rior crucial ligament. The posterior is inserted into the spine 
 of the tibia, in the unequally-divided interval situated between 
 the two prominences of the spine. The posterior ligament 
 sends off a considerable bundle of fibres to be inserted into the 
 posterior crucial ligament. The circular form of the external 
 semilunar cartilage is owing to the insertions of the two an- 
 teiior and posterior ligaments being separated from each other 
 only by a few lines. 
 
 Ligaments of the Internal Semilunar Cartilage. — These are much weaker than the foi- 
 mer. The anterior is inserted a good deal before its fellow, the anterior ligament of 
 the external semilunar cartilage, and the posterior is inserted a good deal behind the 
 corresponding ligament of the externed semilunar cartilage ; hence the semilunar shape 
 of the internal semilunar cartilage, which does not send off any fibrous prolongation to 
 the anterior or posterior crucial ligaments. The ligaments of the inter-articular cartila- 
 ges being inserted into the tibia, these cartilages follow the tibia throughout its course 
 Means of Union of the Knee-joint are two lateral hgaments, a posterior and an anterior, 
 two crucial ligaments, and a synovial capsule. 
 1. Lateral Ligaments. — The external lateral ligament {a, figs. 79 and 80) appears as a 
 
 rounded cord ; it is inserted into the exter- 
 nal tuberosity of the femur, at the point of 
 union of the five anterior sixths with the first 
 posterior, on the prolongation of the line of 
 the fibula ; the precise point of this insertion 
 is a small eminence surmounting a depression 
 which is destined to the tendon of the popli- 
 teus muscle, and is situated in front of an- al 
 other depression destined to the external ge- A 
 meUus ; thence this ligament descends, in a '^ 
 vertical line, to be inserted into the external 
 face of the head of the fibula. This ligament 
 has the appearance of a tendon ; it extends 
 along the anterior border of the tendon of the 
 biceps, with which it may be readily con- 
 founded. 
 
 We should have but an incomplete idea of 
 the means of union which the knee-joint pos- 
 sesses on the outside, if we did not add to the 
 number of its ligaments the tendon of the bi- 
 ceps, which unites in some sort its inferior 
 insertions with those of the external lateral 
 ligament, and the small band of the fascia 
 lata inserted into the anterior tubercle of the 
 tibia, and sending to the external edge of the 
 rotula an expansion, which unites with the 
 tendon of the vastus externus. 
 
 The internal lateral ligament (J c, figs. 79 
 and 80), which is much longer than the exter- 
 nal, has the shape of a broad, thin, pearly- 
 coloured band, arising from the posterior part 
 
 Fig. 79. 
 
 Fig. 80. 
 
 * On asking- myself the question why there should be 
 this difference between the two semilunar cartilages, I 
 have come to the conclusion that the external condyle of 
 the femur, pressing much more upon the tiliia than the 
 internal, on account of the external following the axis 
 
 of the femur, while the internal is turned away from it , t. »»■ l f ♦ 
 
 to the inside, the externa! inter-articular cartilage had to protect a greater portion of the articular «unace ol 
 thti tibia 
 
164 ARTHROLOGY. 
 
 of the internal tuberosity of the femur, on a level with the external lateral ligament, im- 
 mediately below the tubercle into which the third adductor muscle is inserted ; it is 
 turned downward, and a little outward ; it widens in its course, and is inserted, by a 
 broad surface, into the internal border and the anterior surface of the tibia : at this in- 
 sertion, which is at least an inch wide, it is covered by the tendons of the sartorius^ 
 gracilis, and semitendinosus muscles, which glide over this ligament by means of an in 
 tervening synovial bursa. 
 
 Its deep surface is applied to the anterior or reflected tendon of the semi-membrano 
 sus, to the internal semilunar cartilage, to which it intimately adheres, and to the inter 
 nal inferior articular vessels, which are protected by it. 
 
 When the layers of this ligament are removed in succession, it will be seen that the 
 deepest fibres are attached to the superior part of the internal tuberosity of the tibia, 
 and adhere to the synovial membrane. The lateral ligaments are situated much nearer 
 to the flexing or the back part, than to the extending or the fore part of the joint, so 
 that they are stretched during extension, and assist in limiting that motion, but are re- 
 laxed during flexion, to the performance of which they offer no obstacle. 
 
 The posterior ligament, or ligament of Winslow (c, figs. 79 and 81), is much complicated, 
 and is composed, 1. Of a fibrous capsule for each condyle ; 2. Of a median posterior hg- 
 ament, the only one which has been described by authors. 
 
 1. Fibrous Capsule of the Cmidyles. — Each condyle is enveloped with a fibrous husk , 
 that of the external condyle is covered by the external origin of the gemellus, and thai 
 of the internal condyle by the internal. The fibrous capsule of the internal condyle is 
 completed by the internal origin of the gemellus turning around the highest and most in- 
 ternal portion of this condyle. The semi-membranosus muscle sends a fibrous expansion 
 from above downward to this same internal capsule ; the external head of the gemellus 
 is still much more than the internal identified wath the corresponding fibrous capsule, 
 which furnishes a great number of insertions to that muscle. When there is a sesa- 
 moid bone in the external gemellus, it is found in the substance of the external capsule. 
 
 2. The Median Posterior Ligament. — It is composed of several sets of fibres : 1. Some 
 pass obliquely upward and outward, being formed by a considerable expansion of the 
 semi-membranosus ; 2. Others proceed from the tendons of the popliteus and the ge- 
 melli ; and, lastly, 3. Some fibrous bundles, partly vertical and partly oblique, arise from 
 above the condyles of the femur, and are attached to the tibia. Frotn this collection of 
 fibres running in different directions, there results an irregularly-interwoven ligament, 
 perforated by foramina that transmit the ramifications of tlie middle articular artery ; 
 several of the most deeply-seated ligamentous bundles are inserted into the edges of 
 the inter-articular cartilages. 
 
 3. Anterior Ligament, or Ligamentum Patellm {d,figs. 80 and 81). — This name is given 
 to that portion of the tendon of the extensor muscles which ex- 
 tends from the patella to the tibia. This ligament has the thape 
 of a very broad, thick, almost triangular band. Its fibres arise 
 by a broad insertion, of from five to six lines, from the apex of 
 the patella and from the anterior surface of this bone ; they are 
 parallel, pearly-white, and become nearer to each other as they 
 approach the most prominent and lower portion of the anterior 
 tuberosity of the tibia, to which tuberosity they are attached. It 
 should be remarked, tliat this ligament is by no means inserted 
 into the rugged projections which are found on the back part of 
 the apex of the patella. Behind this ligament is a considerable 
 mass of adipose tissue {e,fig. 81), which separates the hgament 
 from the articular synovial capsule , a synovial bursa if, fig. 81) 
 separates it from the anterior portion of the tuberosity over 
 which it glides. This synovial bursa sometimes communicates 
 with the articular synovial capsule, and sometimes is totally dis- 
 tinct from it.* 
 
 Crucial or Interosseous Ligaments. — In the interior of the knee- 
 
 * I should remark that this bursa extends partly over the ligament, which it covers from side to side, ana 
 partly over the anterior tuberosity of the tibia, vfhich is at this point completely deprived of inter-articular car. 
 tilage , so that the facility with which the synovial membrane of the tibia is removed contrasts with the diffi- 
 culty which is experienced in dissecting the synovial membrane which covers the inter-articular cartilages, 
 provided it exists there. The ligamentum patella; forms only a part of the anterior ligament of the knee-joint , 
 this anterior ligament is completed by the rotula and by the united tendons of the rectus femoris, the vastus 
 mtemus and extemus, of which united tendons the ligamentum patellae is evidently a continuation. We see 
 here a very remarkable application of this law, by mea>is of which the articular ligaments are fortified by ten 
 dons, and sometimes completely replaced by ftem ; and I have taken care to observe that it is generally the 
 trochlear joints which exhibit examples of this replacing of ligaments by tendons in regard to extension, be- 
 cause, in the movement of extension, a ligament, being a purely passive means of union, was not sufficient. 
 What would take place if an ordinary ligament were to be substituted for the tendon of the extensor muscles t 
 In the first place, this ligament would have to be extremely long to permit flexion ; but in case it should be 
 long enough for flexion, what would become of it in the movement of extension ? Unless it were endowed 
 witn the extensibility and the elasticity of the yellow ligaments, it would become folded, and would thrust 
 itself between the articular surfaces. It is for this reason that a ligament was required which might be short 
 
ARTICULATIONS OF THE KNEE-JOINT. Ifffe 
 
 joint there are two interosseous ligaments {g i,fig- 78), so arranged as to admit of the 
 most extensive flexion, but to limit the movement of extension. They are called cniciaU 
 because they cross each other like the letter X. They are situated in the deep inter- 
 condyloid fossa, whose sole destination appears to be that of protecting them. The an- 
 terior {g,Jigs. 78 and 81) arises from the external condyle, and passes to the fore part of 
 the spine of the tibia. The •posterior (t, fig. 78) arises from the internal condyle, and is 
 fixed to the back part of the spine. Both are continuous, by a distinct bundle, with the 
 external inter-articular cartilage ; never with the internal. The names anterior and 
 posterior have been given these ligaments, from their inferior insertion ; for superiorly 
 they arise on the same level. Here follows a more minute description of their inser- 
 tions above and below, and of their direction. 
 
 The anterior crucial ligament arises, as a little band flattened from side to side, from 
 the semilunar depression, which is concave superiorly, and is situated on the internal or 
 median surface of the external condyle ; thence it extends from above downward, from 
 without inward, and from behind forward, flattens from before backward, and is inserted 
 in front of the spine of the tibia, upon which spine it encroaches a little by means of some 
 insertions which it takes between the two articular projections constituting the spine. 
 From the external edge of this ligament a few fibres are given off, which extend into the 
 external part of the semilunar cartilage. 
 
 The posterior crucial ligament arises from the external or median surface of the inter- 
 nal condyle in a semilunar depression, entirely similar to the one which is destined to the 
 anterior crucial ligament ; like the latter, it presents a threefold obliquity from above down- 
 ward, from before backward, and from within outward ; it sends a considerable expan- 
 sion to the external inter-articular cartilage, and is inserted back of the spine of the tibia. 
 Thence it follows that the crucial ligaments present a double crossing : 1. A crossing 
 in an antero-posterior direction, and this alone has been observed with attention ; 2. A 
 crossing in a transverse direction ; when the tibia is rotated from within outward, the 
 crossing of these two ligaments increases to such an extent that these two ligaments, 
 strongly pressed against each other, limit the motion ; in the movement of rotation from 
 without inward, on the contrary, as the crossing diminishes, they become relaxed and 
 parallel ; both are stretched during extension, and relaxed during flexion ; there is an 
 exception for the most anterior fibres of the anterior crucial ligament, which are relaxed 
 in the middle state of extension, and stretched during flexion ; but when the extension 
 is considerable, the anterior crucial ligament is also stretched in its anterior fibres, which, 
 being pressed by the condyles, describe a curve anteriorly concave. 
 
 The synovial capsule of this joint is the largest and the most complicated of all that ex- 
 ist in the body. In tracing it from the upper edge of the patella, we find, behind the ten- 
 don of the extensor muscles, a large cul-de-sac {s,fig. 81), sometimes replaced by a dis- 
 tinct synovial capsule, interposed between that tendon and the surface of the femur. In 
 many subjects, this bursa communicates with the synovial capsule of the knee-joint by 
 a more or less considerable opening, and in such cases a circular constriction forms the 
 only trace of separation. On each side of the patella the synovial membrane extends 
 beneath the two vasti, and is sometimes elevated from one and a half to two inches 
 above the articular surfaces ; the prolongation under the vastus externus is much more 
 considerable than that under the vastus internus. The existence of these two prolonga- 
 tions affords an explanation of the sweUings observed at the sides of the knee in dropsy 
 of this joint ; and the greater extent of the external prolongation explains, also, the great- 
 er size of the prominence on the outside. In the inter-condyloid notch the synovial mem- 
 brane envelops the crucial ligaments ; then it is reflected upon the posterior ligament, 
 the lateral ligaments, the semilunar cartilages, the articular surfaces of the tibia, and, 
 lastly, the back of the ligamentum pateUae ; it next sends off a prolongation, containing 
 a few ligamentous fibres, and extending from the lower border of the patella to the front 
 of the inter-condyloid notch. This fold has been incorrectly termed the adipose ligament 
 
 ened or elongated as might be necessary, a tendon being the continuation of a muscle, that is, of an organ at 
 once capable of extension, contraction, and endowed with elasticity. Besides this, a bone was required that 
 might complete the articulation on the outside, that might fill the large space which, during the movement 
 of flexion, would have remained empty between the articular surfaces, and might glide without injury ovor 
 osseous surfaces, and facilitate, at the same time, standing upon the knees. This threefold object has been 
 attained by the patella, a sesamoid bone, which is developed in the substance of the tendon of the extensor 
 muscle of the leg, viz., of the triceps femoris, whose parallelism, at its insertion into the rotula, is destroyed 
 by this bone. 
 
 Independently of the anterior ligament, the knee-joint exhibits a large aponeurotic surface, formed by the 
 femoral aponeurosis, by an aponeurotic expansion of the. fascia lata, and by another aponeurotic expansion fur- 
 nished by the tendons of the sartorius, gracilis, and semi-tendinosus muscles ; to this latter expansion is joined 
 a fibrous lamina, given off by the tendon of the vastus externus and internus, which is attached to the libia. 
 This large anterior aponeurotic surface exhibits, on a level with the tendon of the triceps, a saltier-shaped in- 
 terlacing, which closely adheres to this tendon, and seems destined to serve it as a bridle ; on a level with the 
 patella it exhibits a thin layer, which is sometimes interrupt- 3, and, so to say, lacerated, in consequence of 
 the sub-cutaneous synovial capsule being present ; and on a level with the ligamentum patelte it exhibits 
 fibres running obliquely from above downward and from without inward. 
 
 Finally, I shall point out as appendages of the anterior ligament two proper ligaments of the patella, one m 
 temal, the other external, extending from the edges of the patella to the posterior part of each tuberosity 
 these ligaments are broad and thin, and strongly adliere to the synovial capsule. 
 
166 ARTHROLOGY. 
 
 (ligamentum mucosum, t,figs. 78 and 81). After having furnished this fold, the syno- 
 vial membrane lines the posterior surface of the patella, and becomes continuous with 
 the cul-de-sac behind the extensor tendon. Sometimes the prolongation, known as the 
 adipose ligament, does not exist ; at other times there is more than one. I have seen 
 a fold of the same nature extending from that part of the synovial membrane which lines 
 the extensor tendon to the surface of the femur above the trochlea. No other synovial 
 membrane in the body is provided with so large a number of villous prolongations, which, 
 in some subjects, may be said to give it a shaggy appearance ; they are especially met 
 with around the patella* and the semilunar cartilages. To these prolongations Clopton 
 Havers has given the name of synovial fringes. Some deep fibres of the triceps cruris 
 have been regarded as a special tensor muscle of the synovial capsule. (Vide Trice fs 
 Cruris, Myology.) 
 
 Sub-synovial Adipose Tissue. — From the abundance of this tissue in the knee-joint, its 
 disposition requires some special notice. It is chiefly met with behind the ligamentum 
 patellae {_e,fig. 81), where it forms a very thick layer, filling up the interval between the 
 patella and the synovial membrane. This adipose mass, which raises the ligamentum 
 patellae in the extension of the knee, and which, during flexion, fills the empty space 
 which the movement of flexion produces between the condyles of the femur and the tibia, 
 is situated to the outside of the joint, between the ligamentum patellae and the synovial 
 capsule, which is raised by the mtiss. This mass, on being examined on the side which 
 is contiguous to the joint, exhibits several prolongations, which are somewhat similar to 
 the fatty appendages of the epiploon. These appendages are all lined by a fold of the 
 synovial capsule ; one of these appendages, supported by a fibrous bundle, is attached 
 to the inter-condyloid space, under the name of ligamentum mucosum patellas, which hg- 
 ament is sometimes multiple, and has no other object except to draw to it the fatty mat- 
 ter between the tibia and the femur during flexion of the knee, and to keep that matter 
 in its place during the movement of extension. A large quantity of fatty matter is also 
 found behind the tendon of the triceps above the condyles, where that matter fills the in- 
 terval between this tendon and the corresponding part of the femur. Bundles of fatty 
 matter are, lastly, foimd all around the condyles, as well as in the inter-condyloid notch, 
 and around the insertions of the crucial ligaments. This fat, which may be observed 
 even in individuals in a state of marasmus, except that, under those circumstances, it is 
 more serous and infiltrated, is nowhere more evidently than in the knee-joint, destined to 
 fill the intervals produced between the articular surfaces by certain attitudes. 
 
 Mechanism of the Femoro-tibial Articulation. 
 
 1 . With regard to Strength. — The strength of articulations is generally in direct pro- 
 portion to the extent of the articular surfaces, and there is no joint more advantageously 
 constructed in this respect than the one we have been examining. The reception of the 
 spine of the tibia into the inter-condyloid fossa also tends greatly to increase the strength 
 of the joint, although it forms but an imperfect kind of dovetailing. A third and last con- 
 dition conducive to strength is, the multiplicity of the ligaments, and of the tendons, sup- 
 plying, in some respects, the deficiencies in the fitting. 
 
 2. With regard to Mobility. — The knee, being a hinge-joint, has two principal move- 
 ments, in opposite directions, \iz., flexion and extension; but, as the mutual reception of 
 the surfaces is very imperfect, it is also capable of some slight rotatory motions. 
 
 In flexion, the surfaces of the tibia, defended by their inter-articular cartilages, glide 
 backward upon the condyles of the femur ; and, from the great extent of the articular 
 surfaces of the last bone in that direction, the movement can be carried so far as to per- 
 mit the leg and thigh to touch. In this movement, the lateral, the posterior, and the cru- 
 cial ligaments are relaxed, except the anterior fibres of the crucial ligament, which are 
 stretched ; the ligamentum patellae is stretched ; the patella is firmly applied to the front 
 of the joint, and can neither be moved to the right nor to the left, as may be done during 
 extension. In the position of flexion, the patella fills up, as it were, the great hiatus then 
 existing at the front of the joint between the femur and the tibia. Luxation is impossible 
 during this movement, which is only limited by the mutual contact of the leg and the thigh. 
 
 In extension, the tibia and the inter-articular cartilages glide in the opposite direc- 
 tion. The movement is arrested when the leg is in the same line as the thigh, and 
 whatever muscular feffort be then made, the leg never will pass that limit, excepting 
 trom malformation of the parts. A greater amount of extension is rendered impossible, 
 both by the shape of the articular surfaces, and by the stretching of all the ligaments, ex- 
 cepting that of the patella, which is completely relaxed, and permits of a great mobility 
 of that bone in all directions. One circumstance in the shape of the articular surfaces, 
 which appears to be opposed to any extension beyond the straight line, is the small extent 
 of the trochlea in front ; for, could such extension take place, the glenoid cavities of the 
 tibia would then be applied to a portion of the trochlea, much smaller than themselves. 
 The crucial ligaments are especially intended to limit the movement of extension, as the 
 
 * [Two slight folds of the membrane formed at the sides of the patella have been particularly described 
 inder the very inappropriate name of the alar ligaments.^ 
 
PERONEO-TIBIAL ARTICULATIONS. J67 
 
 following experiment will at once demonstrate. Divide all the external ligaments of 
 the joint ; the crucial ligaments will then alone remain ; then endeavour to extend the 
 leg beyond the ordinary limits ; this wiU be found impossible until these ligaments are 
 divided. That both the crucial hgaments oppose the extension of the limb beyond a cer- 
 tain limit, is proven by dividing these ligaments separately. So long as one remains, no 
 matter which, the extension is limited. An analogous experiment, in which all the hga- 
 ments of the joint (even including the crucial) are divided, excepting the lateral, proves 
 that these are not only opposed to lateral movements, but also limit extension with much 
 force ; this they are enabled to do from being situated nearer to the back than to the 
 front of the joint. Complete luxation can only be effected after laceration of all the hga- 
 ments which hmit extension. An interesting remark, which has been suggested to me 
 by'M. Martin, is, that the crucial hgaments are not only destined to limit the movement 
 of extension, but also — and this is, perhaps, their principal object — to prevent the articu- 
 lar surfaces from leaving each other in the anterior posterior direction during a forcible 
 extension. Thus, the anterior crucial ligament will prevent, in a movement of exten- 
 sion, both the displacement of the tibia backward, and that of the femur forward, and the 
 posterior crucial ligament will prevent both the displacement of the tibia forward, and 
 that of the femur backward. It is also important to remark, that while standing upon the 
 feet, the ham-strings being stretched, these extensor muscles of the leg, which are situa- 
 ted upon the thigh, the rectus femoris, and the vastus externus and intemus, are entirely 
 inactive, as is prgved both by the extreme mobility of the patella and the relaxed state of 
 these muscles in a standing position, and by the absence of all sensation of lassitude in 
 these muscles after the vertical position upon the feet has been continued for a long 
 time. The extension of the knee, therefore, takes place without any co-operation on 
 the part of the muscles, simply through the articular surfaces being juxtaposed in all 
 their breadth, and by the tension of the lateral and crucial ligaments, which keeps the 
 articular surfaces mechanically upon each other.* 
 
 In all these motions the patella is fixed ; it is the femoral trochlea which glides upward 
 or downward upon the posterior surface of that bone. This almost invariable position 
 of the patella depends on the inextensibility of its ligament. The existence of the patella 
 has no effect in limiting the movements of extension ; its only uses, as far as the joint 
 is concerned, are to protect it in front, and to prevent painful pressure in the kneeling 
 posture. Its other and chief uses are connected with the functions of the triceps ex- 
 tensor muscle, in the tendon of which it is developed ; it removes the axis of the muscle 
 from the parallel direction of the lever which it is destined to move. It is movable and 
 depressed during extension of the leg, but during flexion it becomes prominent and fixed, t 
 
 Rotation. — When the leg is semi-flexed upon the thigh, it can be very slightly rotated 
 mward and outward. These movements are performed, not upon the external, but upon 
 the internal condyle as a pivot, so that the external part of the head of the tibia glides 
 forward during rotation inward, and backward during rotation outward. The difference 
 in the part performed by the two condyles in the movement of rotation does not depend 
 upon any peculiarity of structure in the joint, but exclusively upon the arrangement of 
 the acting forces, as we shall see when treating of the muscles. Rotation inward is limited 
 by the mutual contact of the crucial ligaments, whose decussation is increased during this 
 movement. Rotation outward is more extensive, because in this movement the liga- 
 ments are uncrossed, and become parallel. We shall see hereafter that the biceps is the 
 agent of rotation outward, and the popliteus of rotation inward. 
 
 Peeoneo-tibial Articulations {figs. 79 and 80). 
 
 Preparation. — 1. Remove carefully the muscles of the anterior and posterior regions 
 of the leg, which will expose the interosseous ligament, and the anterior and posterior 
 ligaments of these joints. 2. In order to see the interior of the articulations, saw through 
 the two bones in the middle, and then separate them. 3. To gain an idea of the interosseous 
 
 * M. Robert, one of our most distinguished young surgeons, has observed a fact which sustains these ideas, 
 ■which had already been demonstrated by the artificial legs of M. Martin. An individual in whom the patella 
 was fractured, had recovered with a distance of about ten centimeters. The movement of extension by mus- 
 cular contraction was impossible ; but when the limb was extended, it maintained itself in that position with 
 the same force as the limb upon the healthy side. The patient had succeeded, by a sort of artifice, in exe- 
 cuting spontaneously the movement of extension ; he brought the trunk and the pelvis forcibly forward : the 
 femur followed the pelvis, and extension being once effected, this inferior limb, being very strong and immo- 
 vable, assisted in the standing position just as much as the healthy limb. 
 
 t It is during flexion of the leg, and, consequently, when the patella is most immovable, that this bone 
 may be displaced in consequence of some external violence, and in this case, the displacement always takes 
 place to the outside. However, one should suppose that the external condyle of the femur, being much more 
 prominent than the internal, would be opposed to the luxation outward, and favour the luxation inward, "ut 
 we may remark, that the patella, when displaced inward, cannot remain in this position, in which nothing 
 maintains it, and from which the oblique direction of the triceps tends, on the contrary, to bring it back to its 
 natural place ; whereas, when the patella is displaced outward, the prominence of the extorual condyle op- 
 Tjoses the reduction of the patella, which can only be effected by artificial means. It should be remarked, that 
 ttie obliquity downward and inward of the femoral trochlea gives a tendency to the patella of being continuaUj 
 drawn outward by the tendon of the extensor muscles, which is slightly oblique in the same direction as the 
 trochlea. This is so true, that in white swellings of the knee-joiut, the spontaneous displacement of the pa- 
 tella always takes place outward. 
 
168 ARTHROLOGY. 
 
 ligament of the inferior articulation, saw perpendicularly through the lower endc of thp 
 bones of the leg, so as to divide them into an anterior and a posterior portion. 
 
 The tibia and the fibula, which are contiguous at their extremities, are separated iVoir 
 each other along their shafts, the interval being occupied by an aponeurosis, improperly 
 called the interosseous ligament. We have, then, a superior and an inferior peroneo-tibiai 
 articulation, and an interosseous ligament or aponeurosis. 
 
 1. Superior Peroneo-tibial Articulation. 
 
 Tliis articulation is an arthrodia. The articular facette of the tibia, looking downward 
 and outward, is situated behind its external tuberosity. I'he facette of the fibula looks 
 upward and inward ; it occupies the inner part of the upper end of the bone. The means 
 of union are two ligaments : an anterior {g, Jig. 80) and p. posterior {d, Jig. 79). They 
 are composed of parallel fibres, directed obliquely downward and outward from the exter- 
 nal condyle of the tibia to the heaji of the fibula. There is generally a distinct synovial 
 membrane for this joint, but sometimes it is a prolongation from the capsule of the knee. 
 This communication frequently existing between the synovial capsule of the knee and 
 the peroneo-tibial articulation, should condemn, in an amputation of the leg, the practice 
 of extirpating the superior extremity of the fibula. The formidable accidents which 
 might be consequent upon such an extirpation may readily be conceived, and should for- 
 bid the operation, although it has been accomplished without any accident. Its only ob- 
 ject is to prevent the fibula from pressing upon the soft parts. 
 
 2. Inferior Peroneo-tibial Articulation. 
 
 This articulation is an amphi-arthrosis, that is, it is formed between surfaces that are 
 partly contiguous and partly continuous. The former consists of two articular facettes, 
 narrow from above downward, and oblong from before backward ; of these, one is con- 
 vex, and situated upon the internal surface of the lower end of the fibula above the mal- 
 leolus ; the other is concave, and continuous with the inferior or tarsal articular surface 
 of the tibia. They are both covered with cartilage. The continuous surfaces are rough, 
 and much more extensive ; they are triangular in shape, having their bases directed down- 
 ward : the one situated upon the fibula is convex, that upon the tibia is slightly concave. 
 
 The means of union are, two ligaments external to the joint, and an interosseous liga- 
 ment connecting the two triangular surfaces just mentioned. Of the two external liga- 
 ments, one is anterior (i. Jig. 80) and the other posterior {e, Jig. 79). They are both very 
 strong, and composed of thick, shining, parallel fibres, which pass obliquely downward 
 and outward from the tibia to the fibula. They are almost always divided into two dis- 
 tinct bundles. They are both remarkable from descending beyond the articular surfa- 
 ces, so that they increase the depth of the cavity for the reception of the astragalus. 
 The sijnovial membrane of this articulation is a prolongation from that of the ankle-joint 
 The interosseous ligament consists of fibrous bundles, mixed with adipose tissue, which 
 unite the two triangular surfaces so firmly that the fibula is sometimes fractured in at- 
 tempting to rupture the ligaments. 
 
 3. Interosseous Aponeurosis. 
 The name of interosseous ligament is given to an aponeurotic septum {b,figs. 79 and 
 80) placed between the muscles of the anterior and those of the posterior aspect of the 
 leg ; it should rather be regarded as serving to multiply the points of insertion for fibres 
 of those muscles, than as a means of union between the bones of the leg. It is narrow- 
 er below than above, and is composed of fibres running obliquely downward and outward 
 from the outer edge of the tibia to the longitudinal crest on the inner surface of the 
 fibula. As in the interosseous ligament of the forearm, we find some other fibres cross- 
 ing the former at an acute angle. The septum thus formed is interrupted above and be- 
 low for the passage of the tibial vessels ; the peroneal artery and veins traverse the low- 
 er opening ; the anterior tibial artery and veins pass through the upper. 
 
 Mechanism of the Peroneo-tibial Articulations. 
 The fibula is only capable of almost imperceptible gliding movements upon the tibia. 
 This arrangement is directly connected with the mechanism of the ankle-joint. 
 
 Ankle, or Tibio-taksal Joint (Jigs. 79 and 80).* 
 Preparation. — Cut and turn back the tendons that are reflected round the joint, and 
 remove tl\e sheaths of those tendons by which most of the ligaments are covered. The 
 peroneo-calcanean ligament is seen after the tendons of the peroneal muscles have been 
 removed ; the synovial membrane of these tendons only covers it. The peroneo-astra- 
 galian ligament is the most difficult to uncover, on account of its being deeply seated, 
 and separated from the sheath of the muscles of the posterior region by a large quantity 
 of adipose tissue. The internal lateral ligament is seen immediately beneath the sheaths 
 of the tibialis posticus, the common flexor tendon of the toes, and the proper flexor of the 
 
 * We should remark th&t, in order to study this as well as all the other articulations efficiently, it is a great 
 ijvantage to be provided with two joints, of which one is opened, while the other has its ligaments untouched 
 
ARTICULATIONS OF THE ANKLE-JOINT. 169 
 
 great toe. In order to see the deep layer of this ligament, the superficial laj ers must 
 be removed one after the other. 
 
 The tibio-tarsal articulation belongs to the class of angular ginglymt. 
 
 Articular Surfaces. — Both bones of the leg participate in this joint, their 1 >wer extrem- 
 ities being united to form a transversely oblong socket, of which the tibia constitutes by 
 far the greater part. On this articular surface there is an antero-posterior ridge, corre- 
 sponding to the groove of the trochlea on the astragalus, and separating two shallow cav- 
 ities. The socket is bounded by the malleoli on each side. The internal or tibial mal- 
 leolus corresponds to the internal lateral articular surface of the astragalus ; and the ex- 
 ternal or fibular malleolus, to the external lateral facette of the same bone. The tibio- 
 peroneal cavity is completed forward and backward by the lower part of the anterior and 
 posterior peroneo-tibial ligaments. The superior articular surface of the astragalus is 
 a trochlea ; it is oblong from before backward, thus contrasting with the cavity on the 
 lower extremity of the leg,* which is transversely oblong. This trochlea presents a 
 shallow depression, running from before backward, and having an external and an internal 
 edge, the external being the more elevated of the two. The pulley of the astragalus is 
 continuous with its lateral articular surfaces, of which the external is by far the larger. 
 
 The means of union are three external lateral ligaments, two internal lateral ligaments, 
 an anterior {r,Jig. 80) and a posterior {s,fig. 79) ligament, and a synovial capsule. 
 
 The external lateral or. peroneo-tarsal ligaments are three in number; they all proceed 
 from the fibula, either to the astragalus or the os calcis. 
 
 1. The external lateral ligament, properly so called (ligamentum fibulae medium vel per- 
 pendiculare, m,.figs. 79 and 80), is situated beneath the sheath of the peroneus longus 
 and brevis. It arises from the summit of the external malleolus, is directed downward 
 and shghtly backward, to be attached to the outside of the os calcis. It is rounded, and 
 composed of parallel fibres. 
 
 2. The anterior external lateral ligament (ligamentum fibulae anterius, n, fig. 80) arises 
 from the anterior edge of the externed malleolus, and proceeding downward and forward, 
 is fixed to the astragalus in front of its external malleolar facette. It is very short, and 
 broader below than above : it forms one of the two anterior hgaments described by Bi- 
 chat in this joint. 
 
 3. The posterior lateral ligament (ligamentum fibulae posterius, o,fig. 79) is very deeply 
 seated behind ; it extends from the excavation on the inside and behind the external 
 malleolus to the posterior border of the astragalus, immediately above the pulley of this 
 bone. It is directed almost horizontally, or in a slight degree obliquely downward and 
 inward, and is almost parallel to the posterior ligament of the lower peroneo-tibial ar- 
 ticulation. It is composed of very distinct parallel fibres, which are arranged in several 
 layers, the deepest of which are attached to the astragalus behind the facette of the ex- 
 ternal malleolus. The posterior peroneo-astraglagean ligament is very strong. Bichat 
 calls it the posterior ligament of the joint. 
 
 The interTwl lateral ligament is much stronger than the three external ligaments taken 
 together. It is composed of two very distinct layers : 1. A superficial layer, consistiiig of 
 fibres stretched from the apex and the anterior and posterior borders of the internal mal- 
 leolus to the OS calcis, and the upper edge of the lower calcaneo-scaphoid ligament, which 
 it maintains in a state of constant tension. The fibres are long and slightly divergent, 
 but still sufficiently so to have given origin to its name of the deltoid ligament {p,figs. 79 
 and 80). The fibres which are most anterior pass directly forward to the neck of the 
 astragalus, and to the scaphoid ; they form a very thin layer, which has been improper- 
 ly called the anterior ligament of the ankle-joint. 2. Below the above is a deep layer of 
 much greater extent, composed of sliort and strong bundles, passing downward and out- 
 ward from the sununit and sides of the internal malleolus, to the inner surface of the as- 
 tragalus, below the articular facette. + 
 
 Synovial Capsule. — The external surface of this membrane is brought into view in 
 front and behind by removing the tendons and their sheaths ; and if the external and in- 
 ternal lateral ligaments be divided, it will be seen to extend into the inferior peroneo- 
 tibial articulation. It will also be observed that it is tense at the sides, but very loose 
 behind, and more particularly so in front. A great quantity of adipose tissue covers its 
 external surface in these situations. 
 
 Mechanism of the Ankle-joint. 
 This articulation not only constitutes the point at which the weight of the body is 
 
 * Hence, the longest diameter of the astraglagean cavity is from before backwaril ; the longest diametei 
 of the tibio-peroneal cavity is transversely. The extent of the movements of flexion and extension ol '"« '9°' 
 depends upon the disproportion between the antero-posterior diameter of the pulley of the astragalus ana me 
 socket of the leg. , „„„._„„, 
 
 t [The author has omitted, perhaps intentionally, to give a special description of the anterior anu posienor 
 ligaments of the ankle-joint, already alluded to by him. The former extends from the anterior margin oi tne 
 articular surface of the tibia to the corresponding border of the astragalus, a id is called the wno-iarsai itg- 
 ament ; it is very thin, and covered by the tendons of the extensor muscles. The posterior can scarcely De 
 said to exist as a distinct ligament.] 
 
15» 
 
 ARTHROLOGY. 
 
 transmitted to the foot, but also performs a very active part in the movements of pro- 
 gression ; it is therefore so constructed as to unite great strength with the capability of 
 tolerably extensive motion. 
 
 With regard to strength, the following arrangements should be noticed as especially ad- 
 vantageous : 1. The leg being articulated with the foot at a right angle, transmits the 
 weight of the body directly to it, and this transmission being effected in the perpendicular 
 direction, i. c, in a direction in which the articular surfaces mutually oppose each other, 
 has no tendency either to produce fatigue or to rupture the ligaments. The perpendic- 
 ular position of the leg upon the foot during standing is worthy of notice, because of it- 
 self it proves that man was intended for the erect posture, since in this attitude alone 
 does the entire inferior surface of the foot rest upon the ground. It should be also re- 
 marked, that there is no other articulation, excepting that of the head upon the verte- 
 bral column, in which the parts united are habitually perpendicular to each other. 2. 
 The dovetailing effected at this joint, by the reception of the astragalus into the socket, 
 formed by the bones of the leg, is also highly conducive to its strength. This dovetail- 
 ing results both from the pulley-like surface of the astragalus, and from the angular form 
 of the tibio-fibular socket ; and it should be observed, that this latter condition is, as it 
 were, peculiar to the ankle-joint, for in no other do we meet with such abrupt angles. 
 
 With regard to mobility, the tibio-tarsal articulation admits of flexion and extension. 
 There is no lateral motion, the movements of the foot in this direction being almost ex- 
 clusively performed at the tarsal joints. 
 
 Inflexion, the astragalus gUdes backward upon the tibia and fibula, and the back part 
 of the pulley projects behind. Luxation, from an excess of this movement, is almost 
 impossible, for it is limited by the meeting of the neck of the astragalus and the anterior 
 edge of the tibio-fibular sockets. In this movement, the posterior extern2d lateral liga- 
 ment, and the middle and posterior fibres of the internal lateral ligament, are put upon 
 the stretch. 
 
 In extension, on the contrary, the trochlea of the astragalus glides forward upon the 
 corresponding surface ; the synovial membrane is borne upward in front ; the anterior 
 external lateral ligament, and the anterior and middle fibres of the internal lateral liga- 
 ment, are stretched. Luxation is possible during this motion, but is very rare. 
 
 Lateral Movements. — Although the shape of the joint is opposed to movements of this 
 kind, yet it cannot be doubted that the elasticity of the fibula, by allowing the external 
 malleolus to yield a little, may permit them in a slight degree. Nevertheless, the fibula 
 must be fractured, if any force, exerted by the astragalus against the external malleolus, 
 be carried so far as to thrust it much outward. 
 
 Articulations of the Tarsus {figs. 80, 82, 83, 84). 
 
 The intrinsic articulations of the tarsus comprise, L The articulations of the compo-- 
 nent bones of each row. 2. The articulation of the tv/o rows together. 
 
 Preparation. — 1. Remove the tendons situated upon the dor- 
 sum of the foot, and also the extensor brevis digitorum mus- 
 cle. 2. Remove all the muscles of the plantar region. 3. Rub 
 off, by means of a rough cloth, the adipose tissue covering the 
 ligaments (a subject much infiltrated with serum is best adapted 
 for this purpose). 4. In order to gain a clear comprehension of 
 the articulation of the two rows together, remove the astrag- 
 alus from the sort of box in which it is contained, by divi- 
 ding the interosseous ligament which unites it to the os calcis. 
 5. For the examination of the interosseous ligaments, it is ne- 
 cessary to separate the bones by laceration or section of those 
 ligaments ; the resistance experienced in doing this, and the 
 portions of the ligaments remaining attached to the bones, will 
 give a good idea of their strength and situation. 6. In order 
 to obtain a correct notion of all the ligaments together, it is 
 necessary, while studying each, at the same time to examine 
 a foot in which all the joints have been opened above, while 
 the bones are still retained in their situations by means of the 
 plantar ligaments. 
 
 Articulation of the Component Bones of the First Row, or Articula- 
 tion of the Astragalus with the Os Calcis. 
 
 This is a double arthrodia, in which each of the bones pre- 
 sents two articular facettes, separated by a furrow deeper on 
 the outer than on the inner side. Tlie posterior surface of the 
 astragalus (1, fig. 84) is concave, that of tlie os calcis (2) is 
 convex ; in front (1) the opposite obtains, so that there is a mu- 
 tual reception of parts. The means of union, properly speak 
 ing, consist only of an extremely strong interosseous ligament (a, 
 
 Fig.SZ. 
 
ARTICULATIONS OF THE TARSUS. 
 
 171 
 
 /Jg'. 84) formed by ligamentous bundles, of which some are vertical, and others oblique , 
 they are mixed with fat, and occupy the considerable interval formed by the grooves of 
 the two bones, and which is larger towards the outer end. To form a complete idea of 
 this ligament, it is necessary to make a vertical section from before backward, through 
 the middle of the astragalus and os calcis (as in^^. 84). A loose synovial membrane 
 lines the posterior articulation, which is strengthened on the inside by the fibrous sheaths 
 of the tendons of the tibialis posticus, the flexor longus digitorum, and the flexor longus 
 poUicis. There are also about this joint two very small fibrous bundles, one of which 
 is posterior {t, fig. 80 ; a, fig. 83), and the other external {Jb, fig. 83) : some anatomists 
 have described them by the names of posterior and external ligaments. The anterior por- 
 tion of this articulation is often double, from the division of the anterior articular sur- 
 faces into two smaller facettes : it forms part of the astragalo-scaphoid articulation, with 
 which it will be described. 
 
 Articulations of the Component Bones of the Second Row. 
 
 All these joints are very compact, for the five bones which constitute this row act as 
 one only in the movements perfonned by the foot at its tarsal pig, 93. 
 
 articulations. They present for the most part angular facettes ; 
 they have also interosseous ligaments, and are true symphyses 
 or amphiarthroses. 
 
 Articulations of the Cuneiform Bones with each other. 
 
 Articular Surfaces. — The corresponding surfaces of the first 
 and second cuneiform bones present contiguous as well as con- 
 tinuous portions. The contiguous portions are square, and sit- 
 uated at the upper and back part of each surface. The con- 
 tinuous portions are placed in front of the preceding. The 
 corresponding articular surfaces of the second and third cunei- 
 form bones are smooth and contiguous behind, but rough and 
 irregular in front. 
 
 Means of Union. — 1. By dorsal ligaments {c c, fig. 83). This 
 name is given to some very compact fibrous bands stretching 
 transversely from one bone to the other. By their upper sur- 
 faces, on which the longest fibres may be seen, they are in re- 
 lation with the extensor brevis digitorum and with the tendons 
 of the other extensor muscles. Their lower surfaces, the 
 fibres of which are shorter, correspond to the articulations, and 
 to the periosteum of the cuneiform bones, with which they in- 
 terlace. 2. By plantar ligaments. This name may be given 
 to some of the fibres of the interosseous ligaments. 3. By in- 
 terosseous ligaments. These, which are very strong, consti- 
 tute the principal means of union of these joints, and occupy 
 all the rough portions of the corresponding facettes. They 
 so closely unite the bones, that, even when the dorsal liga- 
 ments are removed, it is not easy to open the joints. 
 
 The synovial membrane is merely a portion of the general sjrnovial membrane of the 
 tarsus. 
 
 Articulations of the Scaphoid vnth the Cuneiform Bones. 
 
 Articular Surfaces. — The scaphoid presents the only example in the body of a single 
 articular surface being divided into three facettes by well-marked ridges. Each of these 
 facettes is triangular, and corresponds to a surface of the same form on one of the cunei- 
 form bones. The base of the triangular facette for the first cuneiform bone is below ; 
 the bases of the other two are above (3, fig. 80). 
 
 Means of Union. — 1 . Dorsal ligaments. There are two for the first cuneiform bone, a 
 superior (d, fig. 83), and an internal (c, figs. 83 and 84) ; and only one for each of the oth- 
 ers (//, fig. 83). The dorsal ligaments of the first cuneiform bone pass directly back- 
 ward ; those of the other two are stretched obliquely for^vard and outward. 2. Plantar 
 ligaments. A very strong plantar ligament (a, fig. 82) extends from the tubercle of the 
 scaphoid to the corresponding tubercle of the first cuneiform bone ; it is blended with the 
 tendon of the tibialis posticus, which furnishes a considerable expansion that crosses the 
 direction of the tendon of the peroneus longus, and extends to the third cuneiform, and 
 the corresponding metatarsal bone ; it may be considered as an inferior ligament of the 
 tarsus. The name of plantar ligaments can scarcely be given to some irregular fibres 
 {h,fig. 82) passing from the lower surface of the scaphoid to the second and third cunei- 
 form bones. 
 
 A synovial membrane, common to the three articulations, is continuous with that of the 
 three cuneiform bones. 
 
)J|S ARTHROLOGY. 
 
 Articulation of the Third Cuneiform Bone with the Cuboid. 
 This articulation resembles in every respect those of the cuneiform bones. The means 
 of union are a dorsal ligament {g, fig. 83), consisting of a very strong transverse bundle ; 
 an interosseous ligament, which occupies the entire non-articular portion of the correspond- 
 ing surfaces ; and an ill-defined plantar ligament, consisting of some irregular transverse 
 fibres. The synovial membrane communicates with that of the cuneo-scaphoid articulations. 
 
 Articulation of the Scaphoid with the Cuboid. 
 
 The scaphoid and the cuboid often unite by a small facette. The means of union are 
 an oblique dorsal ligament {i, fig. 83), a very strong interosseous ligament, occupying the 
 whole of the corresponding surfaces of the bones, excepting the small portions which 
 are contiguous ; and a very thick transverse plantar ligament, extending somewhat ob- 
 liquely from the tuberosity of the scaphoid to the cuboid. These ligaments exist even 
 when there are no articular facettes. 
 
 Articulation between the two Rows of the Tarsal Bones. 
 The articulation between the two rows consists of the articulation of the astragalus 
 with the scaphoid and os calcis, the articulation of the os calcis with the cuboid, and, 
 lastly, the union of the os calcis to the scaphoid by means of several ligaments. 
 
 1 . Articulation of the Astragalus with the Scaphoid. 
 
 The articular surface on the head of the astragalus {.I, fig. 84), elongated from without 
 jPt^. 84. inward, and from above down- 
 
 ward, is larger than the glenoid 
 cavity of the scaphoid (3), and pro- 
 jects considerably below it, where 
 it articulates with the anterior fa- 
 cette, or the two anterior semi- 
 facettes of the os calcis. The 
 cavity of reception is completed 
 by a ligament called the inferior 
 calcaneo-scaphoid {b), which occu- 
 pies the triangular interval be- 
 tween the small tuberosity of the 
 os calcis and the scaphoid, and 
 y forms by itself the inner side of 
 
 the cavity of reception. In order to obtain a good view of this ligament, it is advisable 
 to remove the astragalus by cutting and tearing the interosseous ligament that unites it 
 to the OS calcis ; it will then be seen that the ligament we are describing is very strong 
 and triangular, and that it covers not only the lower, but the inner part also of the head 
 of the astragalus. It is often divided into two parts : one being external, narrow, and 
 shaped like a band ; the other internal, much broader and thicker, in relation below with 
 the sesamoid bone of the tendon of the tibialis posticus, and presenting a cartilaginous 
 thickening at the corresponding point. 
 
 Another ligament, called the superior calcaneo-scaphoid {I, fig. 83), must also be regard 
 ed as contributing to wedge in the astragalus ; it extends from the inside of the anterior 
 extremity of the os calcis to the outside of the scaphoid. It is situated upon the dorsum 
 of the foot, in the deep hollow occupied by fat, on the outer side of the astragalus. 
 These two ligaments (the inferior and superior calcaneo-scaphoid) constitute the means 
 of union between the os calcis and the scaphoid. These bones are in no part contigu- 
 ous ; but occasionally we find the os calcis continued into the scaphoid, through the me 
 dium of an osseous lamina, which replaces the lower calcaneo-scaphoid ligament.* 
 
 The OS calcis being very securely articulated with the astragalus, and at the same 
 time very firmly connected with the scaphoid, it follows that the articulation between the 
 scaphoid and astragalus possesses great strength, although the ligaments directly uniting 
 them are by no means powerful ; just as the atlas, which is but slightly connected with 
 the occipital bone by means of its own ligaments, is very firmly fixed by the ligaments 
 stretching from the occipital bone to the axis. Nevertheless, the absence of any very 
 strong and direct means of union between these bones renders it possible for the astrag- 
 alus to be forced by externeil violence out of the sort of osseo-fibrous socket in which 
 it is placed. 
 
 The superior astragalo-scaphoid ligament {s,fig. 80 ; m,figs. 83 and 84) is the only one 
 proper to this joint ; it is semicircular in form, and extends somewhat obliquely forward 
 and outward, from the neck of the astragalus to the margin of the facette on the sca- 
 phoid. It is thin in texture, and consists of parallel fibres ; it is covered by the ex 
 tensor brevis digitorum above, and is lined below by the synovial membrane of the articu- 
 lation between the scaphoid and the astragalus. 
 
 * I have represented a case of this nature (vide Anat. Pathol, avec Planches, liv. ii., pi. v.). 
 
ARTICULATIONS OF THE TARSUS. l73 
 
 2. Calcaneo-cuhoid Arliculahon. 
 
 This articulation is upon the same line as the astragalo-scaphoid ; an anatomical fact 
 which has suggested the ingenious idea of a partial amputation of the foot between the 
 two rows. It belongs to the class we have designated articulations by mutual reception, 
 and of which we have found examples in the sterno-clavicular joint, and the carpo-meta- 
 carpal articulation of the thumb. 
 
 Articular Surfaces (2, fig. 80). — The facette of the os calcis is concave from above 
 downward, while the surface of the cuboid is concave transversely, that is, in a direc- 
 tion at right angles to that of the former. At the lower part of the facette of the os cal- 
 cis there is a horizontal projection, which sometimes stops the knife during the disartic- 
 ulation of the two rows. 
 
 The means of union consist of three ligaments : an inferior or plantar, an internal, and 
 a superior. The inferior -plantar, or calcatieo-cuboid ligament (ligamentum longum plantae, 
 c d,figs. 82 and 84), is the strongest of all the tarsal ligaments, forming a broad band of 
 pearly- white fibres, directed from before backward. These fibres constitute a very thick 
 bundle, and extend from all the under surface of the os calcis, excepting the posterior 
 tuberosities, to the posterior margin of the groove of the cuboid. If the fibres of this 
 ligament be removed layer by layer, we soon arrive at a more deeply-seated ligament, 
 separated from the first by some fatty tissue : it extends obliquely inward, from a tuber- 
 osity at the forepart of the under surface of the os calcis, to all that portion of the infe- 
 rior surface of the cuboid, situated behind its groove. There are, therefore, two inferior 
 calcaneo-cuboid ligaments : a deep (c) and a superficial {d). 
 
 The internal calcaneo-cuhoid ligament {n, fig. 83) is short, narrow, quadrilateral, and 
 very strong ; it is placed at the side of the superior calcaneo-scaphoid ligament, in the 
 deep excavation between the astragalus and the os calcis. These two ligaments are 
 separated in front, but blended together behind, so as to resemble the letter Y. They 
 may be considered as in some measure forming the key of the articulation of the two 
 rows of tarsal bones ; for, during disarticulation, the articular surfaces are easily separ- 
 ated as soon as they are divided. 
 
 The superior calcaneo-cuboid ligament (o, fig 83) is only a very thin, small band of fibres, 
 extending directly forward, from the os calcis to the cuboid. 
 
 Mechanism of the Tarsal Articulations. 
 
 We should examine the mechanism of the tarsal articulations both as regards their 
 strength and their mobility. 
 
 With regard to Strength. — The tarsus forms the fiindamental part of the foot ; one 
 might, in fact, consider the metatarsus and the toes as superadded structures, for, even 
 when they are removed, the foot fulfils its office as a basis of support very efficiently. 
 Surgeons avail themselves of this fact in performing partial amputations of the foot at 
 the tarsal and tarso-metatarsal articulations. 
 
 The construction of the tarsus is, in every respect, adapted to ensure strength ; the 
 number of its pieces, the breadth of the articular surfaces, the strength of the interosse- 
 ous ligaments, and even the mobility of its component bones, all conduce to this end. 
 Suppose, for example, that a single bone had occupied the place of the seven bones in 
 the tarsus, how liable would this long and cancellated lever have been to fractures from 
 the violent shocks to which it is constantly exposed, or from the influence of muscular 
 contraction 1 The tarsus is narrow behind, but enlarged before, so as to increase the 
 transverse extent of the supporting base in that direction ; it is articulated with the leg 
 at a right angle, and, therefore, receives directly the weight of the body, and as directly 
 transmits it to the ground. In order to provide the arm of a lever for the power which 
 raises the weight of the body, it pirojects behind the leg ; indeed, the fitness of an indi- 
 vidual for running and leaping may be, in some degree, calculated from the length of his 
 heel, or, what is the same thing, from the prominence of the tendo Achilles. In stand- 
 ing upon the sole of the foot, the weight of the body is transmitted by the tibia to the 
 astragalus, and from thence to the os calcis. Part of the momentum is lost at the artic- 
 ulation between these bones, and it is easy to comprehend why they are super-imposed, 
 and not arranged in mere juxtaposition. But the astragalus is not placed horizontally 
 above the os calcis, for it inclines inward, downward, and forward ; and from this cir- 
 cumstance, even in standing upon the soles of the feet, the weight of the body is distrib- 
 uted between the os calcis and the anterior range of the tarsus, which is itself subdivi- 
 ded into two rows, but only on the inside, because it is there chiefly that the weight of 
 the body is transmitted by the astragalus. In one attitude, this weight is communicated 
 by the astralagus exclusively to the front row, viz., in standing upon the point of the 
 foot ; and it is then that the division of the tarsus into several bones is especially useful 
 in preventing the injurious effects of shocks transmitted from belOw. There is an im- 
 .nense difference, also, as regards their effects on the system, between falls upon the 
 heels and those upon the points of the feet. 
 
 The mechanism of the tarsal articulations with respect to mobility should be first studi 
 ed in the two ranges separately, and afterward in the articulation of the two rows to- 
 gether. 
 
tT4 ARTHROLOGY. 
 
 1. The bones of the first range, viz., the astragalus and the os calcis, glide upon each 
 other from before backward and from side to side. The lateral glidings assist in the 
 torsion of the foot, which, however, is chiefly performed at the articulation between the 
 two rows. The antero-posterior glidings take place under the following circumstances : 
 when the weight of the body presses upon the upper part of the astragalus this bone slips 
 a little forward, and the foot has a tendency to become elongated, or flattened from above 
 downward, as Camper has remarked. "WTien the pressure ceases, the astragalus returns 
 to its original position. The truth of the assertion, that the foot is an elastic arch, is 
 chiefly established by reference to the nature of the astragalo-calcanian joint. 
 
 2. The bones of the second row are capable of such very slight gliding movements, 
 that they may be considered as forming but a siilgle piece. However, the articulation 
 between the scaphoid and the cuneiform bones is somewhat more movable than those 
 of the cuneiform bones with each other-and with the cuboid. 
 
 3. The chief movements of the tarsus take place between the two rows, and the ar- 
 ticular surfaces are there very favourable to mobility ; for there is in one part a head re- 
 ceived into a cavity (at the astragalo-scaphoid articulation), and in another a mutual re- 
 ception (at the calcaneo-cuboid articulation). These movements consist of a sort of tor- 
 sion or rotation, by means of which the sole of the foot is carried either inward or out- 
 ward. Assisted by slight lateral motions of the astragalo-calcanian joint, they consti- 
 tute what is called adduction and abduction of the foot. They are generally attributed to 
 the ankle-joint ; but, as we have seen, that articulation is limited to flexion and exten- 
 sion ; the sprains, therefore, which result from too extensive movements, either outward 
 or inward, take place at the articulation of the two tarsal ranges, and not at the ankle- 
 joint. When the movement of torsion is carried too far, the external malleolus is forced 
 somewhat outward ; slight gliding motions occur at the tibio-fibular articulations ; the 
 elasticity of the fibula is called into play ; and, if the violence be immoderate, the fibula 
 is fractured. 
 
 Tarso-mktatarbal Articulations {Jigs. 82 to 84). 
 
 , In the formation of these joints, the wedge-shaped tarsal extremity of each metatarsal 
 bone is opposed to one of the bones of the tarsus, the corresponding surfaces being plane 
 and triangular. The first metatarsal bone articulates with the first cuneiform ; the sec- 
 ond metatarsal with the second, and shghtly with the first and the third cuneiform bones ; 
 the third metatarsal with the third cuneiform ; the fourth and fifth metatarsal with the 
 cuboid. From this there results an angular articular line, commencing on the outside, at 
 the projection formed by the tuberosity of the fifth metatarsal bone. This line is directed 
 obliquely forward and inward ; it forms an angle at the third, and again more particularly 
 at the second metatarsal bone, because the third cuneiform bone projects, and is wedged 
 in between the second and fourth metatarsal bones, while the second metatarsal bone 
 projects into the tarsus between the first and the third cuneiform bones. The articular 
 surfaces are held together by dorsal, plantar, and interosseous ligaments. We shall now 
 study each of these articulations separately. 
 
 Articulation of the First Metatarsal Bone with the Tarsus. — ^There are two semilunar 
 facettes in this articulation, one belonging to the first metatarsal, the other to the first 
 cuneiform bone ; the long diameter of these surfaces is directed vertically. The strength 
 of the joint is maintained by a very strong plantar {ffigs. 82 and 84), and a thinner dor- 
 sal {p,fig- 83, and e,fig. 84) ligament. Both these consist of bands directed from before 
 backward. There is a distinct synovial membrane for this joint. We may include 
 among the ligaments of this articulation the aponeurotic expansion given off by the pe- 
 roneus longus to the first cuneiform bone, and also that derived from the tibialis anticus, 
 and attached to the first metatarsal bone. 
 
 The articulation of the second metatarsal hone with the tarsus is effected by the reception 
 of the posterior extremity of that bone within the recess formed by the three cuneiform 
 bones. We met with a similar arrangement, though less perfectly developed, in the 
 carpo-metacarpal articulation of the second metacarpal bone. It is the strongest of all 
 the joints of this kind, and is provided with, 1. Three dorsal ligaments, as in the corre- 
 sponding articulation in the hand ; one median (r, fig. 83), broad, and constantly divided 
 into two bands, which proceed from the second cuneiform bone ; a very strong internal 
 ligament, extending from the first cuneiform bone, the third being external, thin, and at- 
 tached to the third cuneiform bone. 2. With two plantar ligaments, one of which {g, fig. 
 82) is very strong, extends obliquely from the first cuneiform to the second metatarsal 
 bone, and is prolonged upward, so as to become interosseous ; the other is very small, 
 and proceeds from the sharp edge of the second cuneiform to the second metatarsal bone. 
 3. With an interosseous or lateral ligament, extending from the external lateral surface of 
 the first cimeiform bone to the internal lateral surface of the second metatarsal bone. 
 
 The articulation of the third metatarsal hone with the tarsus is maintained by a dorsal liga- 
 ment {s, fig. 82) from the third cuneiform bone. There is no plantar ligament, properly 
 so called, unless an oblique bundle of fibres from the first cuneiform bone be considered 
 as such ; but the fibrous layer, which, after forming the sheath of the tendon of the pe- 
 
ARTICULATIONS OP THE METATARSUS. ITII 
 
 roneus longus, is prolonged to the third metatarsal bone, appears to me to act as a plantar 
 ligament. There is also an external lateral or interosseous ligament, which separates the 
 articulations of the third and fourth metatarsal bones. 
 
 The fourth and fifth metatarsal bones together present a slightly concave surface, which 
 articulates with the convex surface of the cuboid. The means of union consist of a 
 dorsal ligament (t, fig. 83) for the fourth, and an oblique ligament (u), running outward and 
 forward, for the fifth metatarsal bone : they are both loose, but especially the latter. 
 There is no plantar hgament, excepting the sheath of the tendon of the peroneus longus, 
 and a very strong tendinous expansion of the tibialis posticus. The tendon of the pe- 
 roneus brevis acts as an external lateral ligament ; and, besides this tendon, there ex- 
 ists a very strong fibrous band, derived from the external plantar aponeurosis, which 
 extends from the os caleis to the process of the fifth metatarsal bone ; and, moreover, 
 an expansion of the tendon of the peroneus longus, given off as it passes over the cuboid. 
 The articulation of the fifth metatarsal bone is very loose. There is a very strong in- 
 terossemis ligament, stretched from the external lateral facette of the third cuneiform 
 bone to the internal lateral facette of the fourth, and the external lateral facette of the 
 third metatarsal bones. This ligament is analogous to one that separates the articula- 
 tion of the fourth and fifth metacarpal bones from the other carpo-metacarpal articula- 
 tions, and it fulfils a similar purpose here ; so that there are three distinct articulations 
 between the tarsus and the metatarsus, and, therefore, three separate synovial mem- 
 branes ; one for the fourth and fifth metatarsal bones, one for the second and third, and 
 another for the first. 
 
 Articulations of the Tarsal Extremities of the Metatarsal Bones. — These are true amphi- 
 arthroses. The corresponding surfaces are partly contiguous and partly continuous. The 
 contiguous part is nearer to the tarsus ; it is flat, and presents on each bone two small 
 secondary facettes. Contrary to what obtains in the metacarpus, the continuous por- 
 tions are larger than the articular surfaces. There are interosseous, dorsal, and plantar 
 ligaments. The interosseous consist of very strong, short, and compact bundles of fibres, 
 which extend between the rough surfaces of two neighbouring metatarsal bones. The 
 dorsal {b, fig. 83) and plantar {i, fig. 82) pass transversely from one metatarsal bone to 
 another, the plantar being much the larger. 
 
 Articulations of the Digital Extremities of the Metatarsal Bones. — ^Although the digital 
 ends of these bones do not articulate together, yet, as they are in contact and move upon 
 each other, a synovial membrane covers the continuous surfaces and facilitates their 
 movements ; a ligament, also, the transverse ligament of the metatarsus (x, figs. 82 and 
 83), is stretched transversely in front, and unites them loosely together. This ligament 
 is conamon to the five metatarsal bones ; it is formed by the junction of all the anterior 
 ligaments of the metatarso-phalangal articulations, by means of small bundles passing 
 from one to another. It is exposed by opening the sheaths of the flexor tendons. 
 
 Mechanism of the Metatarsal Articulations. 
 
 With regard to Strength. — 1. The five component bones of the metatarsus are so strong- 
 ly united that it is very uncommon for one of them to be broken by itself; the metatar- 
 sus, therefore, can be only fractured by violence sufficient to crush it. 2. The slight 
 ■ mobility of the bones also concurs in increasing the strength of this part of the foot, by 
 permitting it to yield slightly to external impulse. 3. The metatarsus is not uniformly 
 strong throughout ; the first of its bones is the strongest, and upon it a great portion of 
 the weight of the body rests during standing. 
 
 The mobility possessed by the tarsal and the digital extremities of the metatarsal 
 bones requires to be separately noticed. 
 
 1. In the tarsal extremities, the a'ngular arrangement, the mutual wedging of the tar- 
 sus and the metatarsus, as well as the strength and shortness of the external and inter- 
 osseous ligaments, admit of only very obscure gliding movements ; a proof of which ex- 
 ists in the fact, that no example of the luxation of these bones upon the tarsus has, per- 
 haps, ever been recorded. 2. Obscure, however, as these movements may be, they give 
 rise to considerable motions in the digital ends of the bones, where the mobility is fa- 
 voured by the looseness of the transverse metatarsal ligament, and the presence of a sy- 
 novial membrane between the heads of the bones. The first metatarsal bone is not 
 more movable than the others, contrasting remarkably in this respect with the first met 
 acarpal bone. 
 
 Articulations op the Toes {figs. 82 to 84). 
 Metatarso-phalangal Articulations. 
 These articulations belong to the class condyloid, and offer a nearly perfect similarity 
 to the metacarpo-phalangal joints. 
 
 Articular Surfaces. — The head of each metatarsal bone is flattened on the sides, and 
 elongated from above downward, so that it forms a condyle. Each i)halanx presents 3 
 shallow cavity, the greatest diameter of which, contrary to that of the metatarsal surface 
 is transverse. 
 
J 76 ARTHROLOGY. 
 
 Means of Union. — 1. There is an inferior or glenoid ligament (I, Jig. 82), situated on the 
 plantar aspect of the joint ; it is very thick, of the density of cartilage, and consists of 
 interlacing fibres : its edges are continuous, partly with the sheath of the flexor tendons, 
 partly with the transverse metatarsal ligament, but especially with the lateral ligaments 
 of the joint. It is grooved below for the flexor tendons, concave above, to correspond 
 with the convexity of the head of the metatarsal bone, and completes the cavity in which 
 that head is received. Its anterior edge is very firmly fixed to the plantar border of the 
 cavity of the phalanx, of which it seems a continuation ; its posterior edge is free, or, 
 rather, is loosely connected by some ligamentous fibres to the inequalities behind the 
 head of the metatarsal bone, upon the contracted neck of which it is moulded very ex- 
 actly, so that, while protecting the lower part of the joint, it serves also to increase the 
 extent of the surfaces included in the articulation. 2. There are two very strong lateral 
 ligaments (y, figs. 82 and 83), an internal and an external, inserted, not into the depres- 
 sions on each side of the head of the metatarsal bone, but into tubercles situated behind 
 them ; from this origin they proceed very obliquely forward and downward, like flat 
 bands, spreading out as they advance, and terminating partly in the inferior ligament, 
 and partly on the sides of the phalanx. There is no dorsal ligament, properly so called, 
 but the corresponding extensor tendon evidently occupies its place. It is not uncommon 
 to observe a prolongation from the anterior surface of this tendon united to the metatar- 
 sal end of the first phalanx. 
 
 Synovial Capsule. — ^Under the extensor tendon we find a very loose synovial capsule ; 
 it covers the internal surface of the ligaments as well as the articular cartilages. 
 
 The metatarso-phalangal articulation of the first metatarsal bone presents some peculiar- 
 ities which merit special description. 1. The articular surfaces are much larger than in 
 the other similar joints. 2. The head of the first metatarsal bone presents two pulleys 
 on its plantar aspect, separated from each other by a prominent ridge directed from be- 
 fore backward. This construction is connected with the presence of two sesamoid bones 
 {g, fig. 84), developed in the substance of the inferior ligament, which is three or four 
 times thicker than in the other joints. The lateral ligaments are almost exclusively 
 fixed into these sesamoid bones. This joint has also a sort of fibrous ring surmounting 
 the border of the glenoid cavity of the phalanx. 
 
 Articulations of the Phalanges of the Toes. 
 
 These are perfect angular ginglymi. Each toe has two such joints, with the excep- 
 tion of the great toe, which has only one. 
 
 Articular Surfaces. — The anterior extremity of the first phalanx, flattened from above 
 downward, presents a trochlea, which is broader, and prolonged farther on the plantar 
 than on the dorsal surface. On the second phalanx there are two small glenoid cavities 
 separated by a ridge, the cavities corresponding to the sm£dl condyles, and the ridge to 
 the groove of the trochlea just described. 
 
 Ligaments. — 1. As the articular pulley of the first phalanx projects considerably below 
 the second, it is covered in this direction by an inferior or glenoid ligament (m, fig. 82), 
 exactly resembling those of the metatarso-phalangal joints, and perfoming the same 
 functions. 2. The two lateral ligaments (y, figs. 82 and 83) are fixed precisely like the 
 corresponding ligaments of the metatarso-phalangal joints, viz., into the tubercle above 
 the lateral hollow on the anterior extremity of the first phalanx ; and they extend ob- 
 liquely forward to the glenoid ligament and the second phalanx. 3. There is no superior 
 ligament, its place being supplied by the extensor tendon. This tendon is arranged in a 
 particular manner, for it frequently sends off a prolongation (z, fig. 83) from its anterior 
 surface, which is attached to the upper end of the second phalanx. 4. The synovial cap- 
 sule is arranged as in the metatarso-phalangal articulations. There is often a sesamoid 
 bone in the inferior ligament of the phalangal articulation of the great toe. 
 
 Mechanism of the Metatarso-phalangal Articulations. 
 Like all condyloid joints, these admit of movements in four principal directions, and, 
 therefore, are also capable of circumduction. Extension or flexion backward can be car- 
 ried much farther than in any other similar joints. The lateral movements of abduction 
 and adduction are very hmited. Let us examine what takes place during each of these 
 movements, in which the glenoid cavity of the first phalanx glides upon the head of the 
 corresponding metatarsal bone. Inflexion, the first phalanx glides downward upon the 
 head of the metatarsal bone ; the extensor tendon and the upper part of the synovial 
 capsule are stretched by the projecting head ; the upper fibres of the laterad ligaments 
 are also stretched ; these fibres then limit the motion, which, nevertheless, may be car- 
 ried so far that the phalanx may make a right angle with the metatarsal bones. In 
 extension, the phalanx glides upward upon the head of the corresponding metatarsal 
 bone ; the superior fibres of the lateral ligaments are relaxed, while the inferior are 
 stretched : these latter and the inferior ligament evidently limit the motion. In all sub- 
 jects it maybe carried so far as to make an obtuse angle behind ; in some so as even to 
 form a right angle. The movements of abduction and adduction are limited by the meet- 
 ing of the toes. 
 
ODONTOLOGY. 177 
 
 Mechanism of the Phdangal Articulations. 
 As the mechanism of these joints is in every respect identical with that of the fingers, 
 we shall refer to what has been said upon that subject, merely remarking that, eithei 
 from original construction, or from the continued confinement of the toes in tight shoes, 
 their movements, which consist exclusively of flexion and extension, are much more 
 limited than those of the fingers. 
 
 Note on Artkrology. — [It has been considered advisable to include in a single note the following observation* 
 on the general anatomy of the several tissues that enter into the construction of the articulations : 
 
 Cartilages (p. 111). — The substance of the articular cartilages, in many joints, appears to be arr'mged in 
 masses placed side by side, and perpendicularly to the surface of the bone ; and hence the fibrous character 
 presented by them alter slight maceration: nevertheless, they are composed of pure cartilage, unmixed with 
 fibrous tissue. When viewed under the microscope, cartilage is found to consist of a transparent substance, 
 in which are imbedded numerous corpuscles, either placed singly or aggregated in groups. The interme- 
 diate substance is homogeneous in youth, but becomes more or less laminated as age advances. The corpuscles, 
 which are, in fact, metamorphosed primitive cells, are of irregular forms, contain nuclei and nucleoli, and are 
 somewhat flattened near the surface of the cartilage. Occasionally, several are seen occupying a distinct 
 cavity in the intermediate substance. Their average size is tsVs*^ °^ '"^ '"'^'^ '" length, by^ iAj-jth in 
 breadth. Neither nerves, bloodvessels, nor lymphatics are found in the articular cartilages, which, al- 
 though non-vascular, can scarcely be considered unorganized. Cartilage contains 66 per cent, of water ; its 
 principal solid constituent is an animal matter, resolved by boiling into a peculiar variety of gelatin, called 
 chondrin ; it also contains salts of soda, lime, magnesia, and potash. 
 
 The inter-articular cartilages having free surfaces (as those of the knee-joint), are composed of true carti- 
 lage interwoven with fibrous tissue, which particularly abounds at their attached margins. The inter-verte- 
 bral substances, and all other interosseous cartilages, have a similar structure, but contain a greater propor- 
 tion of fibrous tissue. From the two anatomical elements of which these structures consist, they are called 
 ftbro-cartilages. 
 
 The articular borders surrounding the glenoid and cotyloid cavities, generally described with the ligaments, 
 are also composed of fibro-cartilaginous tissue. 
 
 Ligaments (p. 112). — The articular ligaments consist entirelyof fibrous tissue, the obvious component fibres 
 of which are divisible into parallel microscopic filaments, exactly similar to those of cellular tissue (see note 
 on Aponeurologt, infra). They are supplied with but very few vessels and nerves ; they contain 62 per 
 cent, of water, the remainder being almost entirely converted into gelatin by boiling. 
 
 The yellow elastic tissue, of which the ligamenta subflava are composed, differs in minute, as well as in ob- 
 vious characters, from the white fibrous tissue of ordinary ligaments, it consists chiefly of peculiar filaments, 
 intermixed with a few of those of cellular tissue. The proper elastic filaments, examined with the micro- 
 scope, are yellowish and transparent, have a bright aspect and dark outline (very unlike the delicate appesir- 
 ance of the cellular filaments), and are usually curved or bent at their torn extremities. The peculiar char- 
 acter of dividing and uniting again, often assigned to them, is thought to be rather apparent than real, and to 
 depend on an imperfect separation of the larger into their component filaments. The elastic is more vascular 
 than the fibrous tissue. It contains less water (only 29 per cent.), and yields much less gelatin when boiled ; 
 the insoluble residua somewhat resembles coagulated albumen. 
 
 Synovial Membranes (p. 112). — The basis of an articular synovial membrane is cellular tissue, which be- 
 comes more and more condensed towards the free surface of the membrane. The smoothness of this surface is 
 due to a covering of flattened scales (metamorphosed primitive cells) lying upon it, and constituting what is 
 termed an epithelium. The recent discovery of this epithelium upon the surface of the articular cartilages is 
 suflScient to establish the continuity of the synovial membrane over them; a fact which, though doubted by 
 many, is assumed by M. Cruveilhier upon ansilogical grounds. No nerves have been traced into these mem- 
 branes, and the vessels existing in the sub-synovial tissue cease at the margin of the cartilage. The synovia 
 secreted by these membranes is an aqueous solution of albumen and saline matters. It contains more albu- 
 men than the fluid of serous cavities, the lining membranes of which (as we shall hereafter notice) have a 
 similar structure to those just described. 
 
 Besides the articular synovial membranes, two other kinds are usually mentioned, viz., the bursal, including 
 the various bursae, erroneously called bursae mucosae ; and the vaginal, examples of which are met with in th« 
 sheaths of tendons. These two forms will be again referred to in the note on Aponeurology, infra. 
 
 Adipose Tissue. — The constant occurrence, especially in the larger articulations, of masses of fat beneath 
 the synovial membranes, affords an opportunity of jdluding in this place to the minute anatomy of the adipose 
 tissue generally. It may be briefly stated to consist of an aggregation of distinct spherical or oval vesicles, 
 containing the adipose substance, and having numerous vessels ramifying on their transparent and homoge 
 neous parietes. They are held together by the branches of those vessels, and by cellular tissue. In man, the 
 adipose substance is liquid during life, but separates, when obtained in any quantity, into an oily fluid caUed 
 •la'ine, and a solid residue, consisting of two fatty substances, stearine and margarine.] 
 
 ODONTOLOGY. 
 
 Circumstances in which the Teeth differ from Bones. — Number. — Position. — Exterrud Confot 
 mation. — General Characters. — Classification — Incisor — Canine — Molar. — Structure. — 
 Development. 
 
 The teeth, the immediate instruments of mastication, are those ossiform concretions 
 which surmount the edges, and are implanted in the substance of both jaws. The teeth 
 are not bones, though, from possessing an apparent analogy to them, they have long 
 been considered as such. They differ from bones in many respects. 
 
 1. With regard to position. The teeth are naked and visible at the surface, while the 
 bones, and tliis is one of their most important characters, are covered by periosteum. 
 
 2. In anatomical characters. The teeth consist of a bulb or thick papilla, surrounded 
 by a calcareous envelope, composed of two substances, the enamel and the ivory. This 
 calcareous envelope is not traversed by vessels, nor can any trace of cellular tissue be 
 discovered in it. 
 
 3. In regard to their mode of development. In the teeth, the formation of the hard or 
 ossiform matter takes place by successive depositions, from the circumference to the cen- 
 
 Z 
 
178 ODONTOLOGY. 
 
 Ire ; while bones are developed in a precisely opposite direction. No nutritive changes 
 are carried on in the teeth as in bones. Moreover, the teeth are renewed by means of 
 the second dentition ; but there is no analogous phenomenon in the development of bone. 
 
 4. In physiological relations. The teeth do not participate in the diseases of bone, 
 being susceptible only of chemical and physical alterations ; nor is the period of their 
 existence, like that of the bones, of equal duration with the life of the individual. 
 
 5. In regard to chemical composition. They contain a much larger proportion of saline 
 matters, and the enamel is entirely destitute of gelatine. 
 
 All these circumstances prove that the teeth are not bones. We shall now show that 
 they belong to the epidermoid system, and are analogous to the nails and hair. 
 
 1. When examined in the lower animals, they are found to present an uninterrupted 
 series, from such as closely resemble horns or nails to such as present the most perfect- 
 ly characteristic appearances of bone. 2. They have a lamellated structure, hke the nails 
 and hair : in some animals this is very manifest, but is rendered obscure in others from 
 the abundance of calcareous deposite. 3. They are developed in the same manner as 
 horns, nails, and hair. 4. Like them, they present no nutritive phenomena ; they are 
 formed layer after layer, and undergo no renewal of their constituent parts ; they are* 
 inorganic bodies, the products of transudation. 5. According to M. Geoffrey St. Hilaire, 
 the beak of birds, which is evidently a horny structure, belongs to the dental system. 
 
 Number. — In young subjects, at the period of the first dentition, there are twenty teeth, 
 ten in each jaw : in the adult there are thirty-two, sixteen in each jaw. Man, therefore, 
 during the course of his life, has fifty-two teeth, twenty temporary, and thirty-two per- 
 manent. 
 
 The varieties in the number of the teeth are either the result of a deficiency or an excess. 
 
 The varieties from deficiency consist, 1 . In the absence of all teeth, examples 6f which 
 have been recorded by Fox and Sabatier ; 2. In the absence of a great number of teeth, 
 as occurred in an individual who had only the four incisors in each jaw. These deficien- 
 cies are chiefly observed to affect the posterior molares, and frequently they are merely 
 apparent in them from the teeth remaining concealed within the alveoli for a much longer 
 period than usual. Besides, Fox remarks, that there is no tooth which has not occa- 
 sionally been observed to be wanting, either alone or in conjunction with others. 
 
 The varieties /rom excess are observed in the existence of supernumerary teeth, which 
 may or may not range wth the ordinary teeth. The supernumerary teeth either exist in 
 distinct alveoli, or are blended with some other teeth. There are two varieties of this 
 latter condition ; for the supernumerary tooth may either appear to grow upon a primitive 
 or parent tooth {^dens prolifcr of Bartholin), or several teeth may seem as if united into one. 
 
 Position. — The teeth are arranged in two parabolic curves, constituting the dental 
 arches, and corresponding to the alveolar arches, which support them. Into these arches 
 the teeth are fixed, not by articulation, but by the implantation of their roots into the al- 
 veoli, which are moulded exactly upon them. This arrangement induced those anato- 
 mists who regarded the teeth as true bones to admit a peculiar mode of articulation for 
 them, called gomphosis (yd/z^of, a nail). 
 
 The teeth are mechanically fixed in their alveoli ; but yet we must consider the gums 
 and the alveolo-dental periosteum as also forming uniting media. The importance of the 
 latter will be acknowledged, if we consider the effects of scurvy in loosening the teeth, 
 and the ease with which they drop out from the skeleton. 
 
 Each dental arch forms a regular, uninterrupted curve, an aiTangement peculiar to man, 
 for in the lower animals the teeth are of unequal length, and the dental arches have irreg- 
 ular edges ; moreover, instead of their teeth being uninterruptedly contiguous, very con- 
 siderable intervals, at some points at least, are left between them. Each dental arch 
 presents an anterior convex, and a posterior concave surface ; an adherent or alveolar bor- 
 der, which is regularly scalloped ; and a free edge, thin and cutting at the middle, thick 
 and tubercular at the sides ; in the latter situations it has two lips, of which the external 
 is sharper in the upper teeth, and the internal in the lower. The free edge is so arran- 
 ged that all the teeth are upon a level. 
 
 As the superior dental arch forms a greater curve than the inferior, it necessarily fol- 
 lows that the two arches meet hke the blades of a pair of scissors ; but the mode in 
 which they meet is not the same in the middle region, occupied by the incisor teeth, as 
 on the sides, where the molares are placed. Thus, the upper incisors pass in front of 
 the lower, while the external tubercles of the superior molares pass to the outside of the 
 external tubercles of the inferior molares, so that these latter tubercles are applied to the 
 furrow formed between the two rows of tubercles of the upper molares. 
 
 The teeth of the upper jaw, with the exception of the great molaies, are larger, in gen- 
 eral, than those of the lower. I should also remark, that no tooth is placed quite per- 
 pendicularly to its fellow in the other jaw ; for the summit of a tooth in one jaw always 
 corresponds to the interval between the summits of two in the other ; so that the two 
 rows of teeth are not simply in contact, but are really locked together. 
 
 * See note, p. 183. 
 
THE INCISOR TEETH. 179 
 
 External Conformation. — ^The teeth, considered in reference to their form or configura- 
 tion, present some general characters which distinguish them from all other organs of the 
 body ; and also certain specific characters, by which one tooth may be distinguished from 
 another. 
 
 General Characters {figs. 85 to 92). — Each tooth is composed of two very distinct 
 parts : a free portion, projecting beyond the alveolus, named the crown or body {a, figs. 
 85, &c.), and a portion implanted in the bone called the root ox fang (i), the constricted 
 portion between these two constituting the neck (c). The rim of the alveolus or socket 
 does not exactly correspond to the neck of the tooth, but rather to the root, at some dis- 
 tance from the neck, the intervening space being occupied by the gam. 
 
 The axis of the teeth is vertical. This direction is peculiar to the human species. The 
 projection of the teeth forward gives a disagreeable aspect to the countenance, and is al- 
 most invariably connected with a diminution of the facial angle. The axis of all the teeth 
 is slightly inchned, so as to converge somewhat towards the centre of the alveolar curve. 
 
 The length of the teeth (that is, of their crowns) is very nearly uniform. The advan- 
 tage of this arrangement, in preventing one tooth from projecting beyond another, is very 
 obvious. Wlien the teeth are not equal in length, mastication is evidently imperfect ; 
 and therefore the principal object, in cases of fracture of the lower jaw, is to prevent the 
 inconvenience that would arise from irregularity of the dental edge, and which is actu- 
 ally observed when the fragments unite in a wrong position. 
 
 The teeth are only separated from each other by very small triangular intervals, so 
 that they are almost contiguous. When the intervcds are very considerable, mastica- 
 tion is imperfect. 
 
 The general form of the teeth is that of a sUghtly elongated cone, flattened in opposite 
 directions, the base of which is formed by the crown and turned towards the free edge 
 of the dental arch, while the summit, formed by the simple or compound root, presents 
 an opening that penetrates into the cavity of the tooth. The conical form of the root, 
 and the accuracy with which the alveolus is moulded upon it, have a twofold result, viz., 
 that the effort of mastication is disseminated over all points of the socket, and that no 
 pressure is ever experienced at the extremity which receives the vessels and nerves. 
 
 The differences presented by the teetfi, more especially in the crown, have led to their 
 arrangement into three classes, viz., incisors, canine, and molars: the latter have been 
 subdivided into the great and small molars. 
 
 The crown of the incisor teeth {figs. 85, 86) resembles a wedge with the sharp border 
 shaped like a chisel ; as their name implies, they serve the purpose of cutting the food. 
 The crown of a canine tooth {figs. 87, 88) forms a cone with a free pointed apex ; these 
 teeth serve to tear the food, whence their name of laniaires : Hunter called them cu'spi- 
 dati, from their having only one point. The crown of a molar tooth {figs. 89 to 92) is 
 cuboidal, the free extremity being provided with tubercles or points, intended to bruise 
 the food as in a mill. The smjdl molars, which have only two tubercles, are called by 
 Hunter bicuspides {figs. 89 and 90). Man alone, of the entire animal series, is possessed 
 of the three kinds of teeth in an almost equal state of development. 
 
 The Incisor Teeth {jigs. 85 and 86). 
 
 These are eight in number, four in either jaw. They occupy the middle of the dental 
 arches, and, consequently, the anterior extremity of the lever of the third order, repre- 
 sented by each half of the jaw. Their position is unfavourable, and, consequently, they 
 are intended only to divide substances that offer but little resistance. This class of teeth 
 attain their utmost development in rodentia ; as in the rabbit, beaver, &c. 
 
 General Characters. — The crotcn (a) is wedge-shaped ; its anterior surface {fig. 85) is 
 convex, and the posterior concave ; its sides {fi,g. 86) are triangular ; its e-- 85 K 86 
 base is thick and continuous with the root, and its free edge sharp, some- '^' 
 what broader than the base, and cut obUquely upward and backward in , „r" 
 the upper teeth, and downward and forward in the lower. This obliqui- 
 ty of the surfaces, by which the incisors of the two jaws correspond, is 
 the result of their constant friction upon each other, for they cross like 
 the blades of scissors. The cutting edge of an incisor tooth, before it is 
 worn down, is marked by three small denticulations. The root {b) has 
 the form of a cone flattened on the sides ; the anterior border is thicker 
 than the posterior. A small vertical furrow (see fig. 86) occasionally ex- 
 ists on each side, appearing to indicate an original division ; and some- 
 times the point of the root is bifid. Two curved lines, having their concavities directed 
 downward, and united on the sides of the tooth, separate the root from the crown.* 
 
 Differential Characters. — The upper incisors are distinguished from the lowor by their 
 nmch greater size, the fonner being almost twice as large as the latter. In the upper 
 jaw, the middle are distinguished from the lateral incisors, also, by their well-marked su- 
 
 * [It maybe well to observe, that the illustrations arc all taken from teeth of the upper jaw, in which tha 
 general characters of each class are more strongly marked than in those of the lower.! 
 
ODONTOLOGY. 
 
 periority in size. In the lower jaw, on the contrary, the lateral incisors are the larger, 
 though the difference is but shght. 
 
 The Canine Teeth {fgs. 87, 88). 
 These are four in number, two in each jaw. They are situated on either side exter- 
 nally to the incisors, and therefore are nearer to the fulcrum, so that they can overcome 
 a greater resistance. These teeth are most completely developed in the camivora. The 
 tusks of the boar and of the elephant are also canine teeth. 
 
 General Characters. — They are the longest of all the teeth, both in the crown and in 
 Fig. 87. Fig. 88. the root ; they therefore project a little beyond the incisors, particu- 
 larly in the upper jaw. Their crown (a) is thick and irregularly conoid ; 
 it is somewhat enlarged immediately above the neck, and terminates 
 in a blunt point cut obliquely at the sides (see^^. 88), and grooved be- 
 hind. The anterior surface (fig. 87) is convex, the posterior concave. 
 The canine teeth have much longer and larger roots (ft) than any oth- 
 er, and their alveoli are remarkably prominent. The root is flattened 
 on the sides, each of which presents a vertical groove traversing its 
 entire length (see^^. 88). 
 
 Differential Characters. — The superior canine teeth are distinguished 
 from the inferior by their greater length and thickness. The roots cor- 
 respond to the ascending process of the superior maxilla, and in some 
 subjects are prolonged to the base of that process. The length of their root explains the 
 difficulty of extracting them, and the accidents by which this operation is sometimes fol- 
 lowed. There are several preparations in the museum of the Faculty of Medicine, in 
 which the canine teeth are seen developed in the substance of the ascending process, 
 and reversed, so that the crown is turned upward and the root downward. 
 
 The Molar Teeth {fgs. 89 to 92). 
 The molar teeth are twenty in number, ten in each jaw. They occupy the last five 
 alveoli on either side, and, consequently, are nearer to the fulcrum than all the other teeth : 
 they are, therefore, most advantageously placed for exercising a powerful pressure upon 
 any substances we may desire to break between the teeth. The instinctive motion by 
 which, in order to crush a very hard body, we place it between the molars, is evidently 
 connected with this arrangement. These teeth are most highly developed in herbivora. 
 The general characters which belong to all the molars are the following : 1. The great 
 extent of their grinding surfaces, which far exceed those of the incisors and canine ; 
 2. The absence of all obliquity at their summit, the anterior and posterior surfaces be- 
 ing parallel, instead of approaching each other, so as to form a cutting or angular bor- 
 der : this character is evidently connected with the preceding one ; 3. The inequalities 
 of their grinding surfaces, which are marked by eminences and depressions ; 4. The round 
 or even cubical form of the crown ; 5. The shortness of the vertical dimneter of the crown ; 
 6. The multiplicity of roots. 
 
 The molars are divided into two classes, according to their difference in size, and the 
 number of tubercles upon their grinding surfaces. The smaller are called small molars, 
 or bicuspides ; the larger, great molars, or multicuspides. It should be remarked, that in 
 the first dentition, all the molars, without exception, are multicuspides. 
 
 The small molars or biscuspides {figs. 89 and 90) are eight in number ; four in each 
 jaw, two on the right, and two on the left side. They are distinguished by the names 
 first, second, &,c. They are situated between the canine teeth and the great molars. 
 The small molars of the upper jaw correspond to the canine fossae. 
 
 General Characters. — The crown (a) is irregularly cyhndrical, flattened from before 
 Fig. 89. Fig. 90 backward, with its long diameter directed transversely. The anterior 
 and posterior surfaces, which correspond to the two neighbouring 
 teeth, are plain (see fig. 90). The internal and external {fig. 89) sur- 
 faces are convex ; the free or grinding surface is armed with two tu- 
 bercles or points, separated from each other by a furrow. Of the two 
 tubercles the external is the larger. The crown of the small molars 
 has been compared to that of two small canine teeth united. The root 
 (b) is generally simple, but sometimes double or bifid. When simple, 
 it has a deep vertical groove upon each side ; when it is bifid, the sep- 
 aration is never so deep as in the great molars. 
 Differential Characters. — The lower bicuspides are distinguished from the upper by 
 their smaller size, by a slight projection of the crown inward, and by the external tuber- 
 cle being worn down. In the upper bicuspides, the two tubercles are separated by a 
 deep furrow ; in the lower, on the contrary, the furrow is more shallow, and the tuber- 
 cles are sometimes united by a ridge. The second upper bicuspid has generally two 
 roots {figs. 89 and 90), by which it is distinguished from the others. Tlie first lower 
 bicuspid, somewhat smaller than the second, has most commonly but one tubercle, viz 
 the external. This gives it more resemblance to a canine tooth. 
 
STRUCTURE OF THE TEETH. 
 
 181 
 
 The great molars or multicuspides (figs. 91 and 92) are twelve in number ; six in each 
 jaw, three on one side, and three on the other. They are named pig_ gj, pig 93 
 
 nmnerically, proceeding from before backward, first, second, and ^ „ <' 
 third. The last is also called de-ns sapicntia, on account of its 
 tardy appearance. They occupy the most remote part of the 
 alveolar border. 
 
 General Characters. — The crown (a) is pretty regularly cuboid. 
 The anterior and posterior surfaces (see fig. 92), by which these 4 ] 
 teeth correspond, are flat ; the external and internal surfaces 
 (fi,g. 91) are rounded. The grinding surface is armed with four 
 tubercles (dcntes guadricuspides), separated by a crucial furrow, 
 which is occasionally replaced by small depressions. lu some teeth a fifth tubercle may 
 be found. In almost all the tubercles are of unequal size, and cut into facettes. The 
 crown of the great molars resembles two small molars united. The root (b) is always 
 compound ; it is most commonly double or triple, and, in this case, one of the roots has 
 a longitudinal furrow. Sometimes it is divided into four or five parts, variable both in 
 length and direction. The roots are either divergent or parallel ; and occasionally, after 
 separating, they approach each other again, curving like hooks, so as to embrace a more 
 or less considerable portion of the jaw bone. Such teeth (which are called dents harries) 
 it is impossible to extract without pulling away the included portion of the jaw also. 
 Each root of these teeth exactly resembles the single roots of the teeth already descri- 
 bed, with the exception of being smaller. 
 
 Differential Characters of the Upper compared with the Loicer Molars. — I . Contrary to 
 what was observed with regard to the other teeth, the crowns of the lower great molars 
 are a little larger than those of the upper. 2. They are slightly bent inward, while those 
 of the upper great molars are quite vertical. 3. The lower great molars have only two 
 roots, an anterior and a posterior. These roots are very strong and broad, flattened from 
 before backward, deeply grooved longitudinally, and bifurcated at the points. The upper 
 great molars have at least three roots {figs. 91 and 92), one internal and two external. 
 It is very easy, then, to distinguish between the molar teeth of the two jaws. 
 
 Individual Characters of the Great Molars. — 1 . The first great molar is distinguished 
 from the other two by its size, in which it generally exceeds them. 2. The third great 
 molar, or wisdom tooth, is distinguished from the first and second by its evidently 
 smaller size ; by its crown having only three tubercles, two external and one internal ; 
 by its shortness ; and by its roots being, in certain cases, more or less completely joined 
 together. However, even where the roots of these teeth are united, we always find the 
 trace of the characters proper to the series of molar teeth to which they belong ; i. e., 
 the vestige of three roots, an internal and two external for the upper wisdom teeth, and 
 of two roots, an interior and a posterior for the lower. 
 
 No teeth present so many varieties as the last molares, which occasionally even remain 
 buried in the substance of the maxillary tuberosity. 
 
 Structure of the Teeth. 
 
 The crown of each tooth contains a cavity {d, figs. 93, 94) corre^onding with it m 
 shape. This cavity is prolonged with contracted dimensions into ^^ gg y. g^_ 
 
 the centre of the root, and opens by an orifice of variable size at w- • 
 
 the apex of the simple or compound cone, represented by the fang. 
 The dimensions of this cavity are in an inverse proportion to the 
 age of the tooth ; so that it is largest at the earliest periods, but 
 during the progress of years it becomes entirely obliterated. It 
 contains a soft substance constituting the dental pulp. A tooth, i;|| 
 therefore, is composed of two substances, an external hard or c<w- 
 ftcai porhoTi, which is unorganized,* and an internal organized pulp. 
 
 The dental pulp, contained in tfte cavity of the tooth as in a 
 mould, has the same form as the tooth to which it belongs. This 
 pulp is cormected with the dental vessels and nerves by means of 
 a nervous and vascular pedicle, which, after penetrating the dental cavity through the 
 orifice in the apex of the root, and traversing the small canal, becomes continuous with 
 it. From analogies, the accuracy of which will be seen in studying the development of 
 the teeth, the pulp may be regarded as a bulb or large papilla, and appears to consist of 
 a nervous expansion traversed by a great number of vessels. Its arteries are derived 
 from the internal maxillary ; the nerves belong to the superior and inferior maxillary 
 branches of the fifth pair. A membrane, rather difficult of demonstration on account of 
 its tenuity, envelops the pulp, which is extremely sensitive, is the seat of toothache, 
 and to it alone must be referred all that has been said regarding the vitality and sensi- 
 bility of the teeth. 
 
 The hard or cortical portion is composed of two substances, one of which covers th«> 
 
 * Sfie note, p. 183. 
 
|S2 ODONTOLOGY. 
 
 crown, and has been called the enamel (e, figs. 93 and 94), from a comparison with the 
 vitreous layer or glaze of porcelain ; the other, constituting the entire root and the in- 
 terior of the crown, is the ivory (/), improperly designated the bony •portion of the tooth. 
 The enamel is thickest on the grinding surface of the tooth ; it diminishes in thickness 
 as it approaches the neck, at which part it terminates abruptly. The prominence of the 
 curved line, indicating the termination of the enamel, gives rise to the constriction call- 
 ed the neck. 
 
 By comparing, and, in some degree, contrasting the peculiar characters of the enamel 
 and the ivory, we shall be better able to assign to each their respective properties. 
 
 1. The enamel is of a bluish- white, milky colour, and semi-transparent ; the ivory is 
 yellowish-white, and has an appearance like satin. 
 
 2. The enamel, examined in fragments of the crown, exhibits fibres perpendicularly 
 implanted upon the ivory, and pressed closely to each other. The ivory, on the contra- 
 ry, is formed of concentric layers,* the fibres of which are generally parallel to the long 
 diameter of the tooth. 
 
 3. Both substances are excessively hard ; but in this respect the enamel is superior 
 to the ivory, for it will strike fire with steel, and is much less easily worn down by use ; 
 it can even turn the edge of a file. This excessive hardness, a principal element of im- 
 mutability, explains how the teeth are preserved uninjured as long as the enamel re- 
 mains entire, and, on the other hand, the facility with which they decay when once it 
 has been removed. The great brittleness of the enamel, which is one of its most char- 
 acteristic properties, is also owing to this extreme hardness. 
 
 4. In chemical composition, the enamel and ivory present important diflferences, indi- 
 cated in the following tables : 
 
 Ivory. 
 
 
 Enamel. 
 
 
 Phosphate of lime ... 
 
 61-95 
 
 Phosphate of lime ... 
 
 85-3 
 
 Fluate of lime .... 
 
 210 
 
 Fluate of lime .... 
 
 3-2 
 
 Carbonate of lime ... 
 
 5.30 
 
 Carbonate of lime 
 
 8-0 
 
 Phosphate of magnesia - - 
 
 1-25 
 
 Phosphate of magnesia 
 
 1-5 
 
 Soda and chloride of sodium 
 
 1-40 
 
 Membranes, soda and water 
 
 2-0 
 
 Cartilage and water ... 
 
 28-00 
 
 
 
 It follows, therefore, that the principal chemical distinction between these substances 
 depends on the existence of cartilage, that is, of an animal matter in the ivory, and on 
 its absence in the enamel. The presence of cartilage in ivory forms a trace of resem- 
 blance between this substance and bone ; and this is farther strengthened by the result 
 of the action of heat, by which both are similarly aifected. Between the true bones and 
 the ivory there is, however, all that diflference by which a living tissue is distinguished 
 from a solidified product of secretion. I admit, then, a complete want of vitality both in 
 the ivory and the enamel of the tooth ; nevertheless, there are some phenomena which 
 appear to contradict such an opinion. 
 
 1. The cortical substance of the tooth affords a much more perfect sensation of such 
 bodies as come in contact with it than either the nails or hair. 
 
 3. Weak acids, particularly vegetable acids, cause a peculiar sensation when they are 
 applied to the teeth, rendering the shghtest touch extremely painful ; a sensation gener- 
 ally expressed by saying that the teeth are set on edge. 
 
 But if, on the other hand, we reflect that the substance of the teeth is never affected 
 by inflammation, that it never becomes the seat of any tumour or diseased product, and 
 that it is worn away by rubbing and by the file, in the same way as an inorganic body, 
 without any attempt at reparation or any evidence of the existence of a nutritive pro- 
 cess, we must be led to admit the absence of vitality in these organs, and to explain the 
 foregoing facts as dependant simply upon transmission. 
 
 Lastly, the hardness, fragility, and mutability of the enamel and ivoiy vary in differ- 
 ent individuals ; hence the difference in the durability of the teeth, and their liability to 
 change. It must not be imagined that the ivory, when exposed, is susceptible of caries 
 or necrosis ; its changes are entirely of a chemical nature. The contrary opinion pre- 
 vailed only so long as the teeth were considered true bones, and yet it has exercised an 
 influence over the language of surgery which is not yet removed ; thus, we are in the 
 habit of speaking of a carious or necrosed tooth, and to describe them as affected with 
 exostosis, and even with spina ventosa. 
 
 It follows, from all that has been said, that the human teeth are simple, i. e., formed 
 by one centre of ivory covered with one layer of enamel. Compound teeth exist only in 
 herbivora, in which animals mastication consists of a most extensive grinding move- 
 ment ; nor are they met with except among the molar teeth. The characteristic feature 
 of a compound tooth is the division of the crown into a greater or smaller number of 
 lesser crowns, each of which consists of a centre of ivory covered by a layer of enamel. 
 All these crowns are united into one by a third substance, called the cement or crusta pe- 
 trosa, of which the tartar of the human teeth will afford a sufficiently good idea.t 
 
 * See not«, infra. 
 
 t tRecent researches into the structure of the teeth have brought so many interesting facts to light, that It 
 la necessary to notice the result of these discoveries. 
 
DEVELOPMENT OF THE TEETH. 
 
 183 
 
 Development of the Teeth, or Odontogeny. 
 
 The study of the development of the teeth is one of the most interesting parts ol 
 their history. It embraces the description of the phenomena that precede, accompany, 
 and follow the eruption of the first and second sets of teeth. 
 
 First, Temporary, or Provisional Teeth. 
 
 Phenomena which precede their Eruption* — If the jaws of a foetus of two or three 
 months be examined, it will be seen that they are marked by a broad and deep groove, 
 divided by very thin septa into so many distinct sockets for the reception of the dental 
 germs. The alveolar groove is closed at its free border by the membrane of the gum, 
 which is stretched over a sort of thin, and, as it were, indented crest. This crest is 
 formed by a tissue to which some anatomists have given the name of dental cartilage ; 
 it is a pale, very strong fibrous tissue, and does not extend either upon the anterior or 
 posterior surface of the bone, which are only covered by the mucous membrane, the gum 
 being as yet confined to the alveolar border. The gingivjd fibrous tissue sends a pro- 
 longation into each alveolus (alveola-dental periosteum), that forms a fibro-mucous sac upon 
 
 Three different structures at least enter into the formation of the human teeth, viz., the ivory, the enamel, 
 and the cortical substance. 
 
 The ivory {a. Jig. 95) consists of a hard, transparent substance, traversed by numerous tubes, about -r^-^th 
 of a hne in diameter, which commence by open orifices at the cavity of the pulp, and extend in an undulating, 
 but nearly parallel direction, towards the surface of the ivory. In this course the tubes fig. 95. 
 
 present secondary and smaller undulations, undergo a dichotomous division, diminish in 
 size, at first gradually, then rapidly, give off numerous lateral twigs, and, finally, divide 
 into extremely minute ramifications, of which some anastomose together, others commu- 
 nicate with small irregular dilatations called calcigerous cells, situated in the transparent 
 inter-tubular substance, while the remainder appear to be lost at or near the surface of the 
 ivory. The cells and tubes both contain calcareous matter, and seem to be analogous to 
 the corpuscles of bone and the ramified lines radiating from them. In human teeth the 
 cells are very minute ; but in those of many animals they are much more distinct, and 
 present a striking analogfy to the osseous corpuscles. 
 
 The hard inter-tubular substance is not homogeneous, but, as may be clearly seen in 
 young and growing teeth, is comjxjsed of fibres arranged parallel to the tubes, which ap- 
 pear to have distinct parietes. It consists of animal tissue, combined with a large 
 amount of calcareous salts ; and it is the scat of by far the greater proportion of the 
 earthy matter contained in tlie ivory of the tooth. 
 
 The enamel {b,fig. 95) is composed of hexagonal and transversely striated fibres, about 
 x^th of aline in diameter, arranged parallel to each other, and applied by their internal 
 extremities to numerous corresponding depressions on the surface of the ivory, a delicate 
 intervening membrane serving to connect the two structures. Near the neck of the 
 tooth, the enamel fibres rest almost perpendicularly, near the apex of the cro\vn, more 
 or less obliquely upon the surface of the ivory ; moreover, they are often slightly waved 
 or curved. Previously to the eruption of the tooth, each fibre contains an appreciable 
 quantity of organic matter, which, at later periods, almost entirely disappears. 
 
 The cortical substance (c,fig. 95) consists of a thin osseous layer developed on the ex- 
 ternal surface of the fangs, and, as life advances, extending even into their interior, and 
 encroaching upon the cavity of the pulp. It differs in no essential particular from true 
 bone, containing the characteristic corpuscles, and anastomosing tubuli of that tissue. 
 It has been found, also, on the fangs of the teeth of most mammalia, and of a few reptiles 
 and fishes ; in some instances, direct communications have been discovered between the tubes of the ivory 
 and the cells and tubuli of the cortical substance. The cement, or crusta petrosa, existing on the crowns of 
 the compound teeth of the lower animals, also contains corpuscles and tubuli like those of bone, and may, per- 
 haps, be regarded as an analogous deposite to the preceding, differing from it only in situation. 
 
 From a perusal of the preceding summary, it will be seen that not only has much additional knowledge 
 been acquired regarding the structure of the teeth, but that many of the statements of M. Cruveilhier must 
 now undergo considerable modification. Thus, 1. The crusta petrosa bears no resemblance to the tartar of the 
 teeth, which is merely a deposite from the saliva. 2. Even simple teeth contain a third element in their struc- 
 ture, besides the ivory and enamel. 3. Instead of being inorganic Iwdies, the teeth are possessed of a complex 
 organization, which, we may add, is uniform throughout each species, and often sufficiently characteristic to 
 be of the highest utility to the zoologist, &c. 4. A remarkable affinity has been established between the 
 teeth and bone, as far as regards the structure of the cortical substance and the ivory.] 
 
 * [The earliest stage in the development of the teeth, described in the text, is that in which the dental pulps 
 are situated at the bottom of closed sacs ; it has long been familiar to anatomists, and is now called the saccu- 
 lar stage. A. condition antecedent to this, in which the future sacs are as yet open follicles, was first described 
 by Arnold, but we are indebted to Mr. Goodsir (Edin. Med. and Surg. Journ., No. cxxxviii.) for the following 
 connected history of the origin of the pulps and sacs of the temporary and permanent teeth : 
 
 Origin of the Pulps and Sacs of the Temporary Teeth. — In the upper jaw of a foetus, about the sixth week, 
 between the lip and a semicircular lobe constituting the early condition of the palate, is situated a denression of 
 the form of a horseshoe. During the seventh week, this begins to be divided by a ridge (commencing from 
 behind) into two grooves, of which the outer forms the recess between the lip andithe future external alveolar 
 process, while the inner constitutes the primitive dental groove. The mucous membrane along the floor of this 
 groove is then thickened, and from it a single papiUa is developed, and subsequently four others arise from the 
 external lip of the groove, in either half of the jaw. In the mean time, membranous laminie projecting from the 
 external lip, and at first only partially surrounding the papills, unite with similar but smaller processes from 
 the internal lip, so that each papilla (p, 3, Jig. 97) becomes enclosed in a separate follicle {/, S,Jig. 97), com 
 municating with the cavity of the mouth, and lined by its mucous membrane. The papilla now increase in 
 size, and gradually assuming the form of the future temporary teeih, sink within the yet open follicles. At 
 this period, the edges of the latter appear to be developed into opercula (0, 4, Jig- 97), which differ in number 
 and arrangement according to the shape of the crowns of the different teeth, there being two for the incisors, 
 three lur the canine, and four or five for the molars. The formation of the bony alveoli, by the development 
 of an external and internal alveolar process, and of inter-alveolar septa, closely follows the jireceding changes 
 in the soft parts. 
 
 The order and time of appearance of these ten papil';K in the upper jaw are as follow : F rst, those of the 
 
184 
 
 ODONTOLOGY. 
 
 each follicle, perforated at the bottom of the socket for the passage of the dental vessels 
 and nerves. As these prolongations or sacs are intimately connected to the gingival 
 
 {Fig. 96, magnified three diameters.) 
 
 anterior temporary molars during the seventh week ; of the 
 canine teeth at the eighth ; of the central, and then of the lat- 
 eral incisors, about the ninth ; and in the tenth week those of 
 the posterior molars. The formation of the inter- follicular sep- 
 ta, and the other changes in the papillae, follicles, and alveolar 
 borders described above, proceed in the same order, and are 
 completed about the thirteenth week. The condition of the 
 tipper jaw at that period, constituting the end of the follicular 
 stage in the development of the temporary teeth, is seen in 
 Jig. 96, in which the follicles are shown as if held open ; the 
 diagrams 1 to 5 in_^g'. 97, representing perpendicular sections 
 across the jaw, may serve to illustrate the successive changes 
 in the mucous membrane, from the commencement of the 
 groove to the completion of the follicles. 
 
 During the fourteenth week, a small crescentic depression 
 (c, 5, Jig. 97) is formed immediately behind each of the folli- 
 cles, the mouths of which are now closed by their opercula, 
 but without adhesion ; the lips of the groove, -which at this time is called the secondary dental groove, are now 
 applied to each other (6, fig. 97). With the exception of the ten depressions just mentioned, and a small por- 
 tion situated beyond the posterior temporary molar follicle, adhesion of every part of the groove now takes 
 place, proceeding from before backward. The follicles are thus converted by the fifteenth week into shut 
 sacs is, T,fig. 97), while the enlarged papilla constitute the dental pulps (p, 7). The relation of the parts in 
 this, the saccular, stage in the development of the temporary teeth, is represented at 7, fig. 97. 
 
 Independently of a few subordinate differences, the changes in the lower jaw are similar, and occur in the 
 same order, each step in the process being somewhat later than the corresponding one in the upper. 
 
 Origin of the Pulps and Sacs of the Permanent Teeth.— It has been stated above, that during the general 
 adhesion of the dental groove occurring at the fifteenth week, the part posterior to the second temporary molar 
 follicle (in either half of the j-iw) still remains open ; in this situation, a papilla, sunk in an open follicle, ap- 
 pears 'during the sixteenth week. At the twentieth, the fundus of this follicle is converted into a sac, and 
 the papilla into the pulp of the anterior permanent molar tooth, which is thus the earhest to appear of those 
 of the second set, and is farther characterized by being developed (like the papillae of the temporary teeth) 
 from the primitive dental groove, and on the same level with them. At the end of this week the hitherto open 
 portion of the groove is entirely closed by adhesion of its lips, but its walls still remain disunited, and a cavity 
 is thus formed, situated between the sac of the anterior permanent molar and the surface of the gum ; this is 
 the posterior cavity of reserve, from which the pulps and sacs of the second and third molars are subsequently 
 developed. 
 The ten depressions (c, 6) formed behind the follicles of the temporary teeth during the secondary condi- 
 
 f^W 
 
 i^ 
 
 tion of the dental groove (6, fig. 97), in consequence of their escaping the general adhesion of its lips and sides, 
 Fig. 98. Fig. 98.* 
 
 
 are converted into as laany c#rities, called the anterior cav- 
 ities of reserve (c, 7), whfch gradually elongate and recede 
 into the substance of the gum. Pulps and folds (analogous 
 to the opercula of the temporary follicles) are developed 
 within them, appearing first in the anterior cavities ; and 
 they eventually become the sacs of the ten anterior perma- 
 nent teeth, assuming a position behind and above those of 
 the miUc teeth in the upper, and behind and below them in the lower jaw (see? to \%fig- 97 ; aXso fig. 98, and 
 a, figs. 101, 102), each occupying corresponding recesses {a, fig- 102) in the alveolar border. 
 
 At this time, owing to the great relative increase in the size of the dental sans, that of the anterior perma- 
 nent molar (a, i,fig- 98*) is forced backward and upward into the maxillary tuberosity of the upper, and intc 
 the coronoid process of the lower jaw (a 2) ; and the large posterior cavity of reserve (6 2) is drawn in the same 
 direction. At birth, the length of the alveolar border increases relatively, and this sac again sinks to a level 
 with those of the temporary teeth (o 3). The cavity of reserve (6 3), having now resumed its former poaitioc 
 
DEVELOPMENT OP THE TEETH. 185 
 
 membrane, by pulling gently upon the latter we can raise the follicles from their recep- 
 tacles, and completely lay bare the alveoli. 
 
 The follicle or dental germ consists essentially of a membraiie, containing a sort of pe- 
 diculated papilla, known as the bulb or dental pulp. 
 
 1. The membrane of the follicle, after having clothed the sac just described as lining the 
 alveolus, is reflected upon the vessels and nerves which form the pedicle of the bulb, and 
 appears to be prolonged upon the bulb itself : this, however, has not yet been demon- 
 strated. The membrane of the follicle, therefore, resembles the serous membranes in 
 forming a shut sac, the inner surface of which is free and smooth, and the outer adhe- 
 rent. A transparent viscid fluid occupies the space between the bulb and the alveolar 
 portion of the membrane. 
 
 The following is the order in which the follicles of the first set of teeth appear. To- 
 wards the middle of the third month of foetal life there are four distinct follicles in each 
 jaw ; at the end of the third month a third follicle appears in each h£ilf of the jaw, and 
 a fourth and a fifth towards the end of the fourth month. 
 
 2. Of the dental bulb. In the earliest stages the membrane of the dental follicle only 
 contains a fluid, which is at first reddish, and afterward yellowish-white ; but towards the 
 third month a small body makes its appearance, rising as a papilla from the bottom of 
 the alveolus.* This papilla is abundantly suppUed with vessels and nerves, and pro- 
 gressively increases in firmness and in size. A very thin pedicle, consisting of the den- 
 tal vessels and nerves, affords attachment to it, so that it is suspended like a grape. 
 This papilla, dental bulb, or pulp, gradually acquires the characteristic form of some par- 
 ticular tooth, of which it presents an exact model, constituting the nucleus around which 
 the tooth itself is deposited. The first part developed upon this papilla is the crown of 
 the tooth, on which we already find indications of the various eminences and depressions 
 subsequently exhibited by it. 
 
 The development of the hard portion commences towards the middle of pregnancy. 
 The production of the ossiform matter upon the surface of the bulb is eflfected by a pro- 
 cess of secretion ;+ it begins by the deposition of some small laminae, or very delicate 
 scales {I, Jig. 99), upon each projection of the pulp : they are at first pUable and elastic, 
 but gradually become more consistent. These laminae or scales constitute so many 
 formative points for the tooth, and have been compared to the points of ossification in 
 bones. The incisor and canine teeth have only one scale ; the bicuspides have two, 
 and the great molares as many as there are tubercles. These small scales so intimate- 
 ly embrace the pulp upon which they are moulded, that it requires some force to detach 
 them ; and yet their inner surface, as well as the outer, is very smooth. It should be 
 remarked, that the pulp has a much more vividly red colour at the points covered by the 
 scales. The scales are visible in the lower jaw at an earlier period than in the upper. 
 
 The following is the order in which they appear : the middle incisors are visible from 
 the fourth to the fifth month ; they are soon followed, 1 . By the lateral incisors. 2. By 
 the first or anterior molar, which appears from the fifth to the sixth month. 3. At a short 
 
 and shape, elongates backward, and a pulp is developed in its fundus, -whicli is converted before the fourth 
 year into the sac of the second permanent molar. About the sixth or seventh year, the remaining part of the 
 cavity once more elongates backward, and forms the pulp and sac of the third permanent molar, or wisdom 
 tooth. Each of these sacs undergoes changes in its relative position in the jaws, similar to those experienced 
 by the anterior permanent molar, at first receding backward and upward, and then descending behind, and on 
 a level with the sac immediately anterior to it. 
 
 From the preceding observations, it follows that the palps and sacs of both the temporary and permanent 
 teeth have a common origin from the gastro-intestinal mucous membrane ; that a papilla is first formed, after- 
 ward surrounded by and sunk into a follicle, which latter is then converted into a closed sac ; and hence the 
 origin of the terms papillary follicular, and saccular, applied to these several conditions. 
 
 It moreover appears that all the temporary teeth, and also the anterior permanent molar, originate from the 
 primitive dental groove ; and that all the permanent teeth, except the anterior molar, are developed from cav- 
 ities of resen-e commenced during its secondary condition. 
 
 For an account of the changes occurring in the pulps aud sacs of the two sets of teeth during the saccular 
 and eruptive stages, the reader may now refer to the text, remembering, however, that the term follicle is there 
 applied to the entire dental germ in its saccular condition, consisting of a closed sac and its contained pulp.] 
 
 * [The papilla of a temporary tooth appears even before the formation of the open follicle, and therefore 
 long prior to its conversion into a shut sac. (See note, p. 183.)] 
 
 t [The ivory is no longer regarded, by the best authorities, as a secretion from the surface of the dental 
 pulp, nor the enamel as a similar product from the parietal layer of the lining membrane of the sac. A micro- 
 scopic examination of these two structures in their perfect condition is, indeed, alone sufficient to throw con- 
 siderable doubt on the old opinion adopted in the text. The researches of Schwann into their mode of devel- 
 op-oient have again elucidated the subject. It has been observed that the globules in the centre of the dental 
 pulp are primitive nucleated cells, analogous to those found in the early condition of all organic tissues ; that 
 at the surface of the pulp these cells assuro« a cylindrical form and a perpendicular arrangement, but still con- 
 tain nuclei ; that they adhere in places to the ossified scales, and correspond in size (not to the tubuli) but, to 
 the fibres of the inter-tubular substance in a growing tooth. From these facts Schwann concludes that th« 
 formation of the ivory, likethat of all other organized tissues, is effected by a metamorphosis of primitive nu 
 cleated cells ; in other words, that it is developed by a progressive transformation and ossification of the superfi- 
 cial cells of the dental pulp — a theory which recent observations in Great Britain would seem to have confirmed. 
 
 Similar evidence is advanced by him to prove that the enamel is formed in a similar manner from the pulp^y 
 enamel membrane, occupying the upper portion of the sac. The hexagonal fibres, of which the surface of this 
 membrane consists, are, in fact, prismatic, nucleated cells, resting perpendicularly on a tissue, in which are 
 other cells of a vesicular form. The hexagonal fibres correspond, therefore, both in form and direction, with 
 those of the perfect enamel ; and, moreover, they are found to agree in size with the membranous remains of 
 the enamel fibres of a growing tooth, after the removal of their earthy matter by means of a dilute acid.] 
 
 Aa 
 
186 
 
 ODONTOLOGY. 
 
 interval from each other, by the canine and the second molar : the scales of all the teeth 
 of the first set have made their appearance by the seventh month, according to the ob- 
 servations of Meckel ; but at the eighth month, according to Blake. 
 
 As development advances the scales enlarge, and gradually uniting (2, fig. 99), form a 
 sheath or shell of ivory, which, during its growth, encloses the pulp, and, by degrees, ex- 
 tends to the vascular and nervous pedicle at the part where it penetrates the alveolus.* 
 The outermost sheath being formed, a second is deposited within it, then a third within 
 that, and so on. The external surface of the bulb secretes the ivory. The enamel is 
 formed from the parietal or alveolar layer of the follicular membrane : at the commence- 
 ment of its formation it is so soft that, in a foetus at the full time, it can be very easily 
 separated from the ivory. It has been asserted by some that the enamel, as well as the 
 ivory, is the product of a secretion from the bulb, from which it has transuded in a liquid 
 state through the different layers of the ivory, and has then solidified upon its surface ; 
 others affirm that the enamel is a sort of crystalline deposite from the fluid surrounding 
 the tooth ; but the greater number of anatomists admit, with Hunter, that the enamel is 
 a product of secretion from the parietal layer,! as the ivory is from the layer of the fol- 
 licular membrane, reflected upon the bulb. This opinion appears to me the more proba- 
 ble, because, on examining with attention the parietal layer, we find on its inner sur- 
 face, near the crown of the tooth, a sort of pulp, or very evident enlargement, particular- 
 ly in the follicles of the molar teeth. This external pulp becomes atrophied as soon as 
 the enamel is formed ; and hence the fang is not covered with enamel, although, after 
 the eruption of the tooth, that part occupies the former position of the crown. This ex- 
 ternal pulp does not exist in some of the dental follicles of certain animals, and we can- 
 not, therefore, be astonished that such teeth have no enamel. Lastly, when this ex- 
 ternal pulp remains after the eruption of the teeth, the secretion of the enamel also con- 
 tinues, like that of the ivory. This is the case with the incisors of the rabbit and the 
 beaver. In these animals the enamel occupies only the anterior surface of the tooth ; 
 consequently, the edge alw&ys remains sharp, from the unequal wearing of the anterior 
 and posterior surfaces. 
 
 From what has been said concerning the phenomena of the formation of the pro vision- 
 ary teeth before their eruption, we may draw the following conclusions : 1 . Of the two 
 constituent parts of a tooth, viz., the corticle or hard portion, and the medullary portion 
 or pulp, the latter is first developed ; and of the two distinct elements of the hard por- 
 tion, viz., the ivory and the enamel, the formation of the ivory is first commenced. 2. 
 The deposition of the cortical substance of the tooth begins at the crown ; the roots are 
 not formed until a subsequent period. 3. The bulb being enclosed within the solidified 
 products which it has furnished, diminishes gradually in size as these press upon it. 
 
 Phenomena which accompany the Eru-ption of the First or Temporary Teeth. — At the time 
 of birth all the teeth are still contained within their alveoli. Exceptions to this rule 
 have been met with in cases where infants have been born with one or two teeth. If 
 the anterior wall of the alveoli be removed at this time, the teeth will already be found 
 considerably, but unequally developed, none having yet reached the bottom of the socket. 
 But after birth, and at periods to be presently indicated, the extremity of the root having 
 reached the bottom of the alveolus, and the farther growth of the tooth in that direction 
 being impossible, it is effected in the direction of the gum, which is compressed, becomes 
 inflamed, and is perforated ; this perforation, however, is not exclusively the result of 
 distension, for the gum is but very slightly stretched when it opens ; and in other cases 
 where it is greatly distended, as by polypi or other tumours, it is not lacerated at all. 
 
 The tooth gradually rises, and the gum moulds itself successively upon the different 
 portions of the crown, and, lastly, upon the neck of the tooth. The division of the gum 
 is a severe process, but still it cannot altogether explain those serious symptoms which 
 frequently accompany the first dentition. 
 
 The eruption of the teeth does not take place simultaneously, but in succession, and 
 in a regular order that admits of but few exceptions. 1. The teeth of the same kind ap- 
 pear in pairs, one on the right side, the other on the left ; 2. The teeth of the lower jaw 
 
 * [The vascular pulp of either a temporary or permanent tooth having more than one fang is, after tho 
 formation of the crown, divided into as many processes by the advancement into it of the gray membrane of 
 the sac. The dental substance still continuing to be produced on every part of the surface of the divided pulp., 
 abridge of ivory is thus formed across the area of the cavity of the tooth between each process (3, 4,jf^. 99), 
 
 (Ft^. 99.) 
 
 around which separate fangs are subsequently developed (5, 6, 7), in the same mannpr ns that around the niK 
 divided pulp of an incisor tooth.] ■• See note, p. 184. 
 
DEVELOPMENT OF THE 'JEETH. 
 
 precede those of the upper in their appearance ;* 3. The middle incisors are cut before 
 the lateral, these before the first molars ; after these come the canine, and then the sec- 
 ond molars. The eruption of the first set of teeth commences towards the sixth month 
 after birth, and terminates at the end of the third or the commencement of the fourth 
 year. The middle lower incisors appear from the fourth to the tenth month, and, soon 
 afterward, the upper middle incisors ; the inferior lateral incisors appear from the eighth 
 to the sixteenth month, and then the superior lateral incisors. The first lower molars 
 are cut from the fifteenth to the twenty-fourth month ; the lower canine from the twen- 
 tieth to the thirtieth ; and the upper first molars and canine soon afterward. In some 
 cases the eruption of the canine and the first molar teeth takes place simultaneously ; 
 sometimes even the canine teeth take the precedence. The second great molars appear 
 from the twenty-eighth to the fortieth month, and thus complete the twenty teeth of the 
 first set. 
 
 Second or Permanent Teeth. 
 
 Phenomena which precede the Eruption.i — The second dentition consists of the eruption 
 of the teeth called permanent, to distinguish them from the temporary teeth. They are 
 thirty-two in number, so that there are twelve additional teeth in the second set. In 
 this dentition, as in the former, we have to study the phenomena which precede, ac- 
 company, and follow the eruption of the teeth. 
 
 The follicles or germs of the second set of teeth correspond to the row of teeth already 
 formed, bony septa intervening between them. They have the following relations with 
 the follicles of the provisionary teeth : 1. The follicles of the additional teeth in the sec- 
 ond set, viz., the last three molars, are situated in the same curve as the milk teeth, but 
 they occupy, of necessity, the lateral extremities of these curves {Jig. 100). 2. The fol- 
 licles of those teeth of the second set that replace others of the first are, on the contrary, 
 situated precisely behind the teeth to which they correspond {a, Jigs. 100, 101, 102). 
 
 These follicles are at first contained in the same alveoli as the temporary teeth ; but. 
 after a certain time, septa are grad- Fig. lOO. 
 
 ually formed between them, pro- _.^— -—f 
 
 ceeding from the bottom of each 
 alveolus towards its orifice (Jigs. 
 101, 102). Nevertheless, for a long 
 time after the formation of these 
 septa, the temporary (a"" a", Jig. 102) 
 and the permanent ("b ^b) alveoli 
 communicate by tolerably large or- 
 ifices (c' c',Jigs. 101, 102), through 
 which proceed the cords (c. Jig. 
 102) connecting the two teeth. The 
 follicles of the permanent teeth do not sensibly difier in their mode of development from 
 those of the provisionary teeth, only the increase of the vascular system of the former 
 coincides with the progressive atrophy of the vessels of the latter. 
 
 Phenomena which accompany their Eruption. — As long as the development of the per- 
 manent teeth can be efiected in a direction towards the bottom of their sockets, the tem- 
 porary teeth remain uninjured ; but when the growth of the permanent teeth influences 
 their upper edges, the alveoli of the first set are compressed, and afterward destroyed at 
 the parts corresponding to the crowns of the permanent teeth Fig. 101. 
 
 (see^^. 101). After this time the alveoli of the first and sec- 
 ond sets form common cavities : the roots of the milk teeth 
 being compressed by the crown of the permanent teeth, under- 
 go a loss of substance, become loosened, and may be detached 
 by the slightest effort, each tooth being retained in its place 
 only by the sort of ring formed by the gum around its neck. 
 
 The shedding of the milk teeth is not always effected in the 
 way we have described, viz., by a previous destruction of their 
 root. Sometimes, in fact, the permanent tooth does not pen- 
 etrate into the alveolus of the corresponding milk tooth ; but 
 this alveolus is gradually wasted away by the constantly in- 
 creasing development of the neighbouring permanent socket, 
 teeth may fall without destruction of their roots, which, however, are then almost always 
 slender, and, as it were, atrophied. Some compression, either exercised upon the pa- 
 rieties of the temporary sockets, or upon the roots of the milk teeth, is almost indispen- 
 sable for their expulsion. When, in fact, the permanent tooth deviates from its natural 
 direfction, and, consequently, does not press upon the milk tooth, this latter remains, and 
 forms a supernumerary tooth. We cannot, then, doubt the influence of this compression 
 upon the fall of the milk teeth ; but anatomists are not agreed as to the immediate cause 
 of the destruction of the temporary alveoli, and of the roots of the teeth contained within 
 
 * [Although the papillae, it wiU be rememliered, appear earlier in the upper jaw.] t See note, p. 183, 
 
 In this case, the milk 
 
188 
 
 ODONTOLOGY. 
 
 them. How does this compression act 1 Does it produce the fall of the milk teeth in a 
 purely mechanical manner, or does it effect this indirectly by the destruction of the den- 
 tal vessels and nerves 1 One author believes the latter to be the principal cause ; but 
 what we have already said regarding the want of vitality in the teeth will abundantly 
 prove that the wearing away of the alveolus and the milk tooth is the result of mechan- 
 ical pressure. 
 
 At the same time it should be observed, that, since the destruction of the roots of the 
 milk teeth leaves no debris, a process of absorption must, therefore, be performed, the ex- 
 citing cause of which is, undoubtedly, the compression above alluded to. It is not neces- 
 sary, as some authors have believed, to assume the existence of a peculiar absorbent ap- 
 paratus, appropriated to this office. 
 The teeth of the first dentition are shed in the space comprised between the sixth and 
 j^ JQ2 the eighth year, the fall of each tooth 
 
 taking place in the same order as its ap- 
 Kr'i^N ' ^1^ /\ pearance. Blake was the first to point 
 
 out the existence of a cord (c. Jig. 102) 
 passing from the follicle of the perma- 
 nent tooth, along a small, long canal (c' 
 c'), behind the alveolus of the milk tooth, 
 and becoming continuous with the gum. 
 It has been supposed that the canal, and 
 the cord placed within it, were intended 
 to direct the tooth during the progress 
 of its eruption. Hence the name of iter 
 dentis given to the canal, and guhernac- 
 ulum dentis applied to the cord, which 
 has been ingeniously compared by M. 
 Serres to the gubernaculum testis. This 
 cord appears to me to be solid,* not hollow ; it is very well marked in the incisor teeth, 
 but forms a mere thread in the molars. Upon the whole, the influence exerted by the 
 iter dentis and gubernaculum upon the direction of the permanent teeth during its erup- 
 tion is by no means constant. 
 
 Order of Eruption. — The first permanent teeth which appear are the first great molars ; 
 they precede the other permanent teeth by a considerable interval, and immediately suc- 
 ceed the milk teeth, coexisting with them for some time ; they have been, therefore, im- 
 properly classed among the first set of teeth in some anatomical treatises. The first 
 great molars are known by the vulgar name of seven years' teeth. The eruption of the 
 permanent teeth takes place in the same order as that of the milk teeth. Below are sta- 
 ted the periods at which each pair are protruded : 
 
 Middle lower incisors from 
 
 Middle upper incisors .... . . " 
 
 Lateral incisors . •. " 
 
 First small molar " 
 
 Canine teeth " 
 
 Second small molar " 
 
 Second great molar " 
 
 Third great molar " 
 
 The greatest irregularity exists in the eruption of this last molar tooth, which is often 
 wanting, and frequently remains, during the whole of life, either partially or entirely en- 
 closed within the substance of the jaw. 
 
 The incisor and canine teeth of the second set are much larger than the corresponding 
 milk teeth. The opposite is the case with regard to the first two permanent molars, viz., 
 the small molars, or bicuspides. It was ascertained by the inquiries of Hunter, that, in 
 this way, there is such a compensation, that the twenty teeth of the first set occupy pre- 
 cisely the same space as the twenty corresponding teeth of the second. This is not a 
 purely speculative question, but one of singular interest in relation to the practice of ex- 
 tracting the milk teeth. The truth of Hunter's assertion may be confirmed by measuring 
 with a thread the space occupied by the twenty temporary teeth, and comparing it with 
 the space occupied by the corresponding teeth of the second set. M. Delabarre has 
 done this upon the same individual at the period of the two dentitions. 
 
 Plienomena which follow the Eruption of the Permanent Teeth. — These relate, 1. To their 
 growth ; 2. To their decadence. 
 
 1. Growth of the Teeth. — ^The teeth of man are not, like those of some animals, the ro- 
 dentia in particular, susceptible of unlimited growth. The enamel of the crown wears 
 away without ever being reproduced. All the facts brought forward in support of the idea 
 of its reproduction are either erroneous observations, or may be interpreted in a different 
 manner. Nevertheless, some changes take place in the interior of the tooth which are 
 worthy of notice. New layers of ivory continue to be secreted; &nO the cavity of the 
 * [Arising from the adhesion of the sides of the elongated part of the cavity of resene.l 
 
 6 to 
 
 8 years 
 
 7 " 
 
 9 
 
 
 8 " 
 
 10 
 
 
 9 " 
 
 11 
 
 
 10 " 
 
 12 
 
 
 11 " 
 
 13 
 
 
 12 " 
 
 14 
 
 
 28 " 
 
 30 
 
 
DEVELOPMENT OF THE TEETH. 199 
 
 tooth is gradually encroached upon, and finally obliterated. Thus the teeth of the aged 
 have neither pulp nor dental cavity. 
 
 2. Decadence of the Teeth. — The fall of the teeth in aged persons is the effect of a con- 
 traction of the alveoli, produced in the following manner : The teeth are dependances of 
 the buccal mucous membrane, and are, as it were, only accidentally placed in the alveo- 
 lar borders, which, from the tonicity or elasticity of their bony tissue, have a constant ten- 
 dency to displace them. In one word, the tooth is to the alveolus like a foreign body, of 
 which it is incessantly tending to free itself This tendency to contract on the part of 
 the alveolus is effectually resisted, so long as the root of the tooth has a tendency to in- 
 crease towards the bottom of the socket ; but it acts with full force when this resistance 
 ceases in consequence of atrophy of the pulp. Then the alveolus, shrinking upon it- 
 self, expels the tooth by a mechanism similar to that by which, during the progress of 
 syphilitic affections, the most healthy-looking teeth are displaced, solely in consequence 
 of the vitality of the pulp being destroyed by the influence of the virus. 
 
 The fall of the teeth in the aged is regulated by no law, either as regards the time or 
 the order in which it is effected. 
 
 Differences between the First and Second Sets of Teeth. — The teeth of the first dentition 
 are distinguished from those of the second by the following characters : 1 . Their colour, 
 instead of being white, like ivory, or clear yellow, is of a bluish or azure white hue. 2. 
 The temporary incisor and canine teeth are always distinguished from the corresponding 
 permanent teeth by their smaller size and the shortness of their roots. 3. The two mo- 
 lars of the first set differ from the two small permanent molars or bicuspids which take 
 their place, and approach nearer in character to the great molars ; from these, however, 
 they are distinguished, by the shortness of their crowns, and by the number of tubercles 
 on them, viz., five ; three on the outside, and two on the inside. 4. Comparative chem- 
 ical analyses of the teeth of the two sets have shown that the milk teeth contain some- 
 what less phosphate of lime than the permanent, and to this circumstance their greater 
 susceptibility of change is due. 
 
 General Observations. — From the description we have given of the teeth, it will be seen 
 that these organs should be looked upon merely as large vascular and nervous papillae, 
 covered by an unorganized calcareous sheath, which is formed by a species of crystalli- 
 zation.* The diseases of the teeth offer nothing incompatible with this theory, for, with 
 the exception of toothache, and the sensation of being set on edge, which are evidently 
 seated in the pulp, the other alterations of which the teeth are susceptible are either me- 
 chanical lesions, such as splitting, cracking, wearing, &c., or chemical changes, as the 
 dry or moist caries, or, lastly, alterations appearing to have their seat in the hard sub- 
 stance of the tooth, but which are really situated elsewhere. Of this nature are the in- 
 crustations with tartar, the product of a vitiated secretion, attributed by several anato- 
 mists, and especially by M. Serres, to some small follicles, the function of which, before 
 the eruption of the teeth, is to produce a fluid to soften the gum preparatory to its perfo- 
 ration by the teeth. Again, exostosis and spina ventosa of the teeth evidently depend 
 upon irregular secretion of the enamel and ivory. The consolidation of fractures of the 
 teeth is explained by the formation of new layers, resembling those which have been 
 seen surrounding bullets in the substance of an elephant's tusk. Lastly, the coloration 
 of the teeth, from the action of madder, is only observed in the layers deposited during 
 its use, and therefore does not prove the existence of any nutritive process in these or- 
 gans, such as takes place in bone. 
 
 With regard to the evolution of the teeth in two distinct sets, it may be inquired what 
 is the object of such an arrangement. Without entering here into the discussion of final 
 causes, it cannot be denied that the second set of teeth would not accord with the com- 
 paratively small size of the jaws in the foetus. 
 
 Use. — 1. The teeth are the immediate agents of mastication. The incisors cut, the 
 canine tear, and the molars grind the food, the position of each being regulated by the 
 resistance they have to overcome. 2. The teeth form a kind of elevated border, which 
 prevents the constant escape of saliva from the mouth. 3. They assist in rendering 
 sounds articulate, by affording a fixed point to the tongue in the pronunciation of certain 
 consonants, called by grammarians dental. 4. The teeth furnish important characters 
 for zoological classifications. Indeed, as they bear a necessary relation to the mode of 
 feeding in different animals, a circumstance that exercises so great an influence over 
 their entire organization, it may easily be conceived that the fonn of the teeth is, to a 
 certain extent, one of the characters by which a summary idea is conveyed of the nature 
 of that organization. At the same time, it is necessary to guard against the evidently 
 erroneous conclusions which some philosophers have delighted in deducing from the ar- 
 rangement of the dental apparatus in man with regard to his fitness for a purely animal 
 or exclusively vegetable diet. Above all, it should be remembered that the mechanical 
 mgenuity of mankind must always form an indispensable element in the solution of every 
 problem of this nature. 
 
 * [It is necessary, in some degree, to modify this definition of the hard portion of the teeth, which, though 
 extra-vascular, and, on that account, probably subject neither to interstitial absorption nor nutrition, cannot 
 be regarded with propriety as unorganized or crystalline bodies. 
 
190 MYOLOGY. 
 
 MYOLOGY. 
 
 The Muscles in general. — Nomenclature. — Number. — Volume and Substance. — Figure. — Di- 
 rection. — Relations. — Attachments. — Structure. — Uses. — Preparation. — Order of Descrip- 
 tion. 
 
 The active organs of locomotion are called muscles.* They are composed of bundles 
 of red or reddish fibres, consisting of fibrin as their basis, and possessing the essential 
 property of contractility, that is, the power of contracting or shortening upon the applica- 
 tion of a stimulus, t 
 
 JVomenclature of Muscles 
 
 The names applied to the various muscles have not been founded upon uniform prin- 
 ciple. Before the time of Sylvius the muscles of any region (of the thigh, for example) 
 were designated numerically, first, second, &c., in the order of their super-position or of 
 their uses. Sylvius first gave particular names to the greater number of the muscles ; 
 and he was followed by almost all succeeding anatomists, especially by Riolanus. In 
 this nomenclature, which is still generally adopted, the names of the muscles are deri- 
 ved, 1. From their situation, as radialis, ulnaris, peroneus, &c. ; 2. From their size, as 
 glutaeus maximus, minimus ; palmaris longus, brevis, &c. ; 3. From their direction, £is 
 rectus abdominis, obliqui capitis ; 4. From their shape, which is generally an imperfect 
 representation, either of certain geometric figures, as rhomboideus, pyramidalis, and sca- 
 lenus, or of well-known objects, as deltoideus, lumbrici, and soleus (from solca, the sole 
 fish) ; 5. From their divisions or complications, as digastricus (from having two bellies), 
 triceps (from having three heads), biceps, complexus, &c. ; 6. From their insertions, as 
 stemo-hyoid, stemo-thyroid, &c. ; 7. From their uses, as flexors, abductors, &c. 
 
 In modem times many attempts have been made to substitute in the place of these 
 vague and generally arbitrary denominations, a uniform nomenclature, derived from the 
 most important consideration, viz., the attachment of the muscles. The nomenclature 
 of Chaussier, however, which is undoubtedly superior to all others, has not been adopt- 
 ed ; first, because a knowledge of the old names cannot be neglected, since they are the 
 only ones employed in a great number of works on medicine and surgery ; and, second- 
 ly, because even the most imperfect denominations, when they have been long in use, 
 are, from this circumstance edone, preferable to any new appellations. 
 
 JVumber of the Muscles. 
 Upon this point, likewise, authors are but little agreed. According to most, the num- 
 ber of muscles is four hundred. Chaussier reduced it to three hundred. These differ- 
 ences arise partly from the fact that the natural limits of the different muscles are not 
 so well marked as those of the bones, for example, and partly because the grounds of de- 
 marcation between the various muscles have not been sufficiently established. The fol- 
 lowing rules may be adopted with advantage : 1. When a number of fasciculi unite, and 
 form a mass, which is isolated both in its body and at its extremities, and fulfils distinct 
 and determinate uses, such a collection should be considered a separate muscle. 2. A 
 muscle should also be regarded as distinct when it is separated from others at one por- 
 tion only of its body, and at the most movable of its attachments. On the whole, what- 
 ever be the mode of demarcation adopted, it will be seen that the number of the muscles 
 greatly exceeds that of the bones ; the reason of this is, that each bone acts as a lever 
 in a great variety of movements, while each muscle acts only in a very limited number 
 of motions. 
 
 Volume and Substance of the Muscular System. 
 
 Of all the systems of organs in the body, the muscular is predominant both in substance 
 and in volume. This great mass of muscular apparatus is a necessary consequence of 
 the unfavourable position of most of the levers represented by the bones. There is very 
 great variety in different individuals, as regards both the volume and substance of the 
 muscular system. Compare, in this respect, the glutaeus maximus of a robust man, and 
 the same muscle in a thin, nervous individual, much emaciated, but yet in perfect health, 
 for still greater differences are produced by disease : size and strength of the muscular 
 system may also be natural or acquired, partial or general. Partial preponderance is 
 most usuEdly acquired, and is commonly the result of exercise. To be convinced of this, 
 it is only necessary to inspect the muscles of certain regions, in individuals whose em- 
 ployment requires the special exercise of those parts. The preponderance of the mus- 
 cles on the right side is produced solely by the habit of using this side more than the 
 other ; it is not, as has been alleged, the result of congenital difference. 
 
 Lastly, the size of one or the other region of the muscular system, in different anim£ils, 
 
 * From nvi)V, a muscle, or /itij, a mouse. 
 
 t It will be seen that, in constructing this definition, the only object has been to distinguish the muscles gen 
 erally from other orgaas, by pointing out their two characteristic properties, viz., their fibrinous comnosition 
 ■ad their contractility. 
 
FIGURE AND DIRECTION OF THE MUSCLES. 191 
 
 is in relation either with their instinctive propensities, their mode of feeding, or their 
 natural attitude, or with some other important peculiarity in their organization. Hence 
 we find, 1. In the lion, the tiger, and other carnivorous animals that tear their prey in 
 pieces, the muscles connected with the inferior maxiUa, the most highly developed ; 2. 
 In the bear, which is a climbing animal, the muscles of the back ; 3. In the hare, whose 
 mode of progression is by successive leaps, the muscles of the hind limbs ; 4. The mus 
 cles of the wing in birds ; and, 5. Those of the lower extremities and the vertebral grooves 
 in man, to whom the erect position is peculiar 
 
 Figure of the Muscles. 
 
 The figure of the muscles is determined upon the foUoviing data : 1. From a compari- 
 son of them with geometric figures or with famihar objects. 2. From the respective ar- 
 rangement of their surfaces, edges, and angles. 3. From their being symmetrical or 
 otherwise. In this latter respect there is a remarkable difference between the osseous 
 and the muscular systems : many bones are symmetrical, or azygos, while almost all the 
 muscles, on the contrary, are asymmetrical, and arranged in pairs. 4. From the relative 
 proportion between their three dimensions ; from this latter consideration, muscles have 
 been divided into three classes, viz., long, broad, and short, concerning each of which we 
 shall make some general remarks. 
 
 The long muscles are chiefly met with in the limbs. Their length is sometimes con- 
 siderable ; and the longest are always most superficial. Very long muscles generally 
 pass over several articulations, and can therefore assist in moving them all. This great 
 length of certain muscles has also another advantage, viz., that it enables them to obtain 
 a fixed point of attachment upon a less movable part, as the trunk, from which they can 
 then act upon the more mobile parts : such is the case with the muscles that move the 
 thigh or the leg. Long muscles are either simple or divided. Sometimes the division 
 occurs at the more movable attachment ; sometimes at that which is habitually fixed. 
 
 The broad muscles occupy the pjirietes of cavities ; they are quadrilateral when all their 
 points of attachment are on the trunk, and triangular when they extend from the trunk 
 to the extremities. When several broad muscles are super-imposed, the fibres of one 
 always cross those of another at an angle ; and this arrangement, by forming a sort of 
 interweaving, greatly augments the strength of the parietes which they assist in forming. 
 This is particularly well shown in the broad muscles of the abdomen. 
 
 The short muscles are generally met with in the same situations as the short bones. 
 It is not the shortness of its fibres, but of its fleshy body that characterizes a short mus- 
 cle. It is important to notice, with regard to these muscles, that a number of them are 
 often arranged in succession, so as to resemble a long muscle. Of this we shall find 
 many examples in the muscles of the vertebral grooves. 
 
 Direction of the Muscles. 
 
 The direction of the muscles is one of the most important points in their history, since, 
 without a knowledge of this, it is impossible to appreciate their uses. Each muscle has 
 an axis or middle line, in which the general action of its fibres takes effect. Few mus- 
 cles are altogether rectilinear ; most are angular or curved ; and almost all undergo cer- 
 tain deviations or reflections in passing round the joints : some, indeed, take a direction 
 at right angles to their primitive course, when they pass over pulleys or hook-like pro- 
 cesses. In muscles of this kind the action is in the direction of the reflected portion. 
 
 The direction of muscles must be studied with reference to the axis of the body, but 
 especially to the axis of the limb or lever, in relation to which they represent the moving 
 power. Many muscles are almost parallel to the axis of the lever upon which they act ; 
 but it should also be remarked that, in certain positions, these same muscles form great- 
 er or smaller angles with their corresponding levers, and may even become perpendicu- 
 lar to them. In this respect the direction of the muscles is not absolute, but is subordi- 
 nate to the position of the levers. 
 
 Some muscles are constantly perpendicular to the levers upon which they act. 
 
 The angles of incidence of the muscles upon their points of attachments are very va- 
 riable, but generally they are more nearly parallel than perpendicular to those points. 
 As the axis of a muscle is not the same as that of its component fibres, it is necessary to 
 study, in each muscle, not only the direction of the fleshy beUy, but that of the fibres also. 
 
 Relations or Connexions of the Muscles. 
 
 In reference to surgery, the relations or connexions of the muscles are among the 
 most important circumstances in their history. 
 
 Relations of the Muscles to the Skin. — Those muscles only which are called cutaneous 
 are immediately connected with the skin ; the remainder are separated from it by apo- 
 neuroses of greater or less density, so that the skin does not participate in the move- 
 ments of the m.uscles, and vice versa. Nevertheless, the changes produced in the form 
 and size of the muscles during their contraction are so decided, that those which lie 
 near the surface are more or less defined through the integuments ; but the projections 
 
192 MYOLOGY. 
 
 corresponding to the bodies of the muscles and the depressions at their attachments 
 are, in a measure, obliterated by adipose tissue, the quantity of which varies in the two 
 sexes and in different individuals. To this latter circumstance are due the differences 
 in the outward characters of the muscular system of the female, as compared with the 
 male ; and of a fat individual, as compared with the one who is emaciated. 
 
 Relations of the Muscles to the Bancs. — In the limbs where the muscles form several par- 
 allel layers around the bones, the belly or thickest part of the muscle always corresponds 
 with the shaft or most slender portion of the bone ; while the ends of the muscle, where 
 it is thinnest, correspond with the expanded extremities of the bone. The relations of 
 the bones with the muscles vary, according as the latter are deep-seated or superficial. 
 The superficial are only in contact with the bones by their extremities or their tendons 
 the deep-seated muscles alone correspond to the bones by their entire length. 
 
 Relations of the Muscles to each other. — The muscles are arranged upon each other in 
 successive layers ; each muscle is covered by a sort of fibro-cellular sheath ; and a loose 
 and moist cellular tissue is interposed between the different sheaths, so as to facilitate 
 the gliding movement and independent contraction of each muscle. This isolation of 
 the muscles does not exist throughout their entire length ; several are often blended 
 together in one conunon insertion, from which they proceed as from a centre, afterward 
 separating from each other. This community of attachment is principally observed in 
 those muscles that perform analogous offices, or that, usually at least, act simultaneously. 
 Most muscles are enclosed in a separate fibrous sheath, which isolates them in their 
 actions, and also in their diseases. Of this we shall find remarkable examples in the 
 rectus abdominis and sartorius. With regard to the relations of their edges, the muscles 
 are sometimes contiguous throughout their entire course, and sometimes separated by 
 intervals, generally of a triangular figure ; and principally important in surgical anatomy, 
 because incisions, for the exposure of vessels, are almost always made in such intervals. 
 
 Relations of Muscles to the Vessels and Nerves. — The muscles serve to protect the ves- 
 sels and nerves, not only in consequence of the thickness of the layers which they form 
 in front of them, but also by the resistance they oppose during their contraction to ex- 
 ternal violence. Near the centre of a limb there is generally a considerable cellular in- 
 terval between the muscular layers, which is intended for the principal vessels and nerves. 
 The existence of such spaces prevents the injury which these vital parts would sustain 
 from compression during the contraction of the muscles. It is also worthy of notice, 
 that whenever a vessel passes through the body of a muscle, we find an aponeurotic arch 
 or ring, which is non-contractile, and in some degree, therefore, obviates the danger of 
 compression during the action of the muscular fibres. I say in some degree, because, 
 in order to render compression of the vessels impossible, the muscular fibres attached to 
 these rings must have proceeded from them as from a centre, diverging in all directions. 
 In this case, the action 5f the muscles would not change the form of the rings, but would 
 tend to increase their diameters in every direction. It is found, however, that they are 
 invariably elongated in one direction and diminished in another, when the fibres of the 
 muscle contract. Bernouilli, indeed, has shown that it is impossible to change the form 
 of a circle, by making one of its diameters greater than the others, without, at the same 
 time, diminishing its capacity ; because, within a given periphery, the most regular fig- 
 ures have the greatest capacity, and the circle is more regular than either the oval or 
 the ellipse. On the whole, however, it must be understood that the contraction of the 
 fibrous rings does not, in any material degree, impede the circulation. 
 
 It should also be remarked, that a distinct fibrous sheath surrounds the vessels and 
 the nerves, serving to isolate and protect them amid the various muscles by which they 
 are surrounded. 
 
 Most of the arteries have accompanying muscles, which may be called their respective 
 satellites : thus, the sartorius is the satellite muscle of the femoral artery, the biceps of 
 the brachial, the stemo-mastoid of the carotid, &c. 
 
 Attachments or Insertions of Muscles. 
 
 The attachments or insertions of muscles constitute one of the most important points in 
 their history, and one which requires to be studied with the greatest care, because the 
 uses of a muscle can be determined from a knowledge of its insertions alone. These 
 insertions should be considered in two points of view : 1. As to the direct insertion of 
 the muscular fibres into the tendons, aponeuroses, or other structures ; 2. As to the in- 
 sertion of the tendons and aponeuroses into the levers represented by the osseous system. 
 
 The muscular fibres themselves are attached, 1. To the skin, of which mode there are 
 numerous examples in the muscles of the face ; 2. To other muscular fibres, as in many 
 muscles of the face and of the tongue ; 3. To cartilages, as in several of the muscles of 
 the chest and larynx ; 4. To aponeuroses, of which they act as tensors, and whose power 
 of resistance they thereby increase; lastly, to tendons or aponeuroses,* that are them- 
 selves attached to the bones. 
 
 The fleshy fibres are inserted into, or become continuous with, the tendons and apo- 
 
 * [The tendons afford examples of the fascicular form of fibrous tissue, for a notice of which see note, tn/jd.) 
 
ATTACHMENTS AND STRUCTURE OF MUSCLES. 193 
 
 neuroses in the following manner : Tlie tendon is prolonged under the form of a mem- 
 brane, either upon the surface or in the substance of the muscle. The results of this 
 arrangement are, 1 . An increase of surface for the attachment of the muscular fibres, 
 which the tendon gathers up, as it were, in order to concentrate their efforts upon one 
 point ; 2. An obliquity in the insertion of the fibres, in reference to the axis of the entire 
 muscle, by which the direction of the power is represented. It may easily be conceiv- 
 ed that this obliquity is of the greatest interest as regards the dynamic relations or ac- 
 tive property of the muscles.* 
 
 One of the most curious circumstances respecting the continuity of a tendon or an 
 aponeurosis with a muscle is the very intimate union between the muscular and fibrous 
 tissues, which is so complete that they are scarcely ever separated by external violence, 
 which, moreover, tends to lacerate the muscle rather than the tendinous fibres. 
 
 It is a fact worthy of notice, and one which we have already had frequent occasion to 
 remark, that the adhesion of any two organic tissues is stronger than the respective co- 
 hesion of each ; so that the tissues themselves will sooner break than admit of separa- 
 tion from one another. 
 
 Insertion of the Aponeuroses and Tendons into the Bones. — A tendon or an aponeurosis 
 forms a species of ligament, by means of which the action of a very large muscle is 
 transmitted to the lever intended to be moved, by a fibrous cord or aponeurotic lamina 
 of small size. A great advantage arises from this mode of economizing the extent of 
 bony surface required for muscular attachments ; for, notwithstanding the extent of 
 surface afforded by the expanded ends of the bones, and by the eminences and ridges 
 with which they are covered, it would be evidently insufficient, were the muscular fibres 
 to be directly attached. 
 
 The existence of tendons and aponeuroses produces also this remarkable result, viz., 
 that the muscular insertions are much stronger than they would otherwise have been. 
 The aponeurotic tissue acts as a transition structure, being in some points of its organi- 
 zation analogous to bone, and in others approaching that of muscle. The analogy be- 
 tween the bony and fibrous tissues is confirmed by the frequent occurrence of ossifica- 
 tion in the latter, even under normal conditions, as may be observed in the formation of 
 the sesamoid bones, and also in the mode by which tendons are attached. It has been 
 observed, in fact, that at the point of junction of the tendons with the bones there is a 
 sort of mutual fusion of the tissues, from which so intimate a connexion results, that the 
 proper substance of the tendons always gives way before they can be separated from the 
 bones, their attachments to which even maceration will scarcely destroy. 
 
 Of the different bones with which a muscle is connected, some remain immovable du- 
 ring its contraction, while others are put in motion ; hence the distinction between Jixed 
 and movable attachments. But this eminently useful distinction must not be taken in an 
 absolute sense ; it is only rigorously true of a very small number of muscles, which, like 
 some of those found in the face, being connected by one extremity with the skin, and 
 by the other with the bones, can give rise to movements only at their cutaneous at- 
 tachments. In the greater number of muscles, on the contrary, although one of the at- 
 taclunents is most commonly fixed and the other movable, yet their relative condition 
 may be changed, and they may become alternately fixed and movable ; it is therefore 
 necessary, in explaining the action of a muscle, carefully to notice the supposed mobility 
 or fixedness of the different attachments at the time. 
 
 In comparing such attachments as are habitually fixed with those that are constantly 
 movable, we shall observe that the former are either numerous or spread out by means 
 of aponeuroses, whereas the latter consist of very accurately-circumscribed tendons. 
 The figurative expressions of head and tail, given to the §nds of a muscle, refer to this 
 arrangement. The fixed attachment of a muscle is usually blended with those of several 
 others, while the movable one is distinct.! In order to facilitate our description, we 
 shall invariably designate the fixed attachment of a muscle, its origin, and the movable 
 attachment, its termination or insertion. 
 
 Structure of Muscles. 
 
 Muscles are composed of two kinds of fibres : 1. Of red or contractile fibres, wYiich form 
 the muscular tissue properly so called ; 2. Of white, strong, and non-contractile fibres, con- 
 stituting the tendons and aponeuroses. In speaking of the ligaments, we mentioned the 
 general properties of tendons and aponeuroses as belonging to the fibrous tissues ; we 
 shall now make a few remarks on the peculiar characters of muscular tissue. 
 
 1. Colour. — Muscular tissue is of a reddish colour, the intensity of which varies in dif- 
 ferent muscles and in different individuals. This colour is not an essential character 
 even in the human subject, for the contractile fibres of the intestinal canal are very 
 
 * In fact, as the tendon, and the aponeuroses by which it is continued into the muscle, represent the direc- 
 tion of the power, the fleshy fibres must necessarily be attached to it more or les.s obliquely. It is not our in- 
 tention to examine here the great loss of power which this arrangement involves. 
 
 t [This assertion must be taken with some limitation. We shall find many exceptions to this general rule, 
 (S we proceed in the description of the muscles.] 
 
 Bb 
 
194 MYOLOGY. 
 
 pale ;* still less is it so in the lower animals, some of which have the entire muscular 
 system perfectly colourless. The red colour of the muscular fibre is independent of the 
 blood contained within the vessels of the muscle. 
 
 2. Consistence. — The consistence of the muscular fibres varies in different subjects . 
 in some it is soft and easily torn ; in others it is firmer and more resisting, and retains 
 for some time after death a degree of rigidity which yields with difficulty to forcible ex- 
 tension. 
 
 Structure. — The muscles may be divided into bundles or fasciculi of different orders, 
 and these, again, into distinct fibres, which are visible to the naked eye, and rendered 
 more apparent, either by dissection, or by the action of alcohol, of diluted nitric acid, or 
 even of boiling water. They are of a variable shape, resembling prisms of three, four, 
 five, or six surfaces, but are never cylindrical. Their length also varies in different 
 muscles, in but a few of which do they extend parallel to each other tliroughout the en- 
 tire length of the fleshy belly. 
 
 Each muscle is surrounded by a sheath of cellular tissue, which also penetrates into 
 its substance, and surrounds both the fasciculi and fibres. This cellular tissue permits 
 the free motion of the different fasciculi upon one another, while it serves, at the same 
 time, to isolate each and combine the whole. + 
 
 The chemical analysis of muscular tissue shows that it is composed of a small quan- 
 tity of free lactic acid (Berzelius) ; gelatin ; some salts ; osmazome in greater or less 
 quantity, according to the more or less advanced age of the individual ; and leucine, a 
 substance extracted from this tissue by the process described by M. Braconnot. {Ann. 
 de Chim. et de Phys., tom. viii.)t 
 
 In addition to the tendinous and fleshy fibres, vessels, nerves, and cellular tissue also 
 enter into the composition of muscles. We have already described the disposition of 
 the cellular tissue contained in these organs ; the mode of distribution of their vessels and 
 nerves will be more appropriately alluded to in the description of the vascular and ner- 
 vous systems.^ 
 
 Uses of Muscles. 
 The muscles are the active organs of motion, constituting the source of the power 
 
 * [The involuntary muscular tissue, of which the above-named fibres afford examples, are, v»ith the excep- 
 tion of the heart, of a much paler colour than the voluntary muscles, to which this division of the present 
 work exclusively refers.] 
 
 t [In reference to the microscopic structure of the voluntary muscles, or those of animal life, it has been 
 ascertained that the smallest fasciculi (corresponding with the prismatic fibres of our author, and with the 
 secondary fasciculi of Miiller), the size of which varies in different muscles, are divisible into transversely-slri- 
 ated fibres (the primitive fasciculi of Miiller), having a uniform diameter in all muscles in the same species, 
 and being themselves composed of still smaller elementary parts named _/t?amcn<* (the primitive fibres of Miil- 
 ler). All these elements of the muscular tissue extend parallel to each other, from one tendinous attachment 
 to another, never having been seen to bifurcate or coalesce. 
 
 In man the fibres vary from y^o^th to -g-^Tfth of an inch in diameter ; the transverse striae upon them are 
 parallel, generally straight, but occasionally slightly waved or curved ; they are situated at intervals of from 
 
 The filaments are varicose or beaded, i. e., alternately enlarged and contracted ; their diameter is from 
 _ ' th to y-f^^nTr''^ °f *" inch. According to the general opinion, they are held together in each fibre by 
 means of a glutinous substance, which latter, according to Skey, constitutes the entire centre of the fibre, the 
 circumference alone being occupied by the filaments. In the larvae of insects, a delicate membranous sheath, 
 sometimes observed projecting beyond the filaments, has been described by Schwann as forming a proper in- 
 vestment of the fibre ; and, by analogy, this is also presumed to exist in man and the other vertebrata. Be this 
 as it may, it is certain that the fibres have no separate sheaths of cellular tissue derived from the common 
 sheath of the muscle, the prolongations of which appear to extend only so far as to enclose the smallest fasciculi. 
 The cause of the striated appearance has, perhaps, not been quite satisfactorily ascertained ; but since the 
 enlargements on the varicose filaments are darker than the constricted portions, and since they are situated 
 at intervals precisely similar to those between the transverse strios of the corresponding fibre, and from some 
 other additional considerations, it has been supposed, with great probability, to result from the enlarged and 
 dark portions of the filaments being arranged side by side. 
 
 For an account of the microscopic characters of the involuntary or organic muscular fibres, see the notes ot 
 the structure of the several viscera, &c., in which they are found, viz., the alimentary canal, trachea, genito- 
 urinary organs, and iris. We may remark here, that the muscular fibres of the heart and of the upper part 
 of the oesophagus are striated, and approach very closely in character to those of animal life.] 
 X [The following analysis of the muscles of the ox is on the authority of Berzelius ; 
 
 Water 77-17 
 
 Fibrin (with vessels and nerves) 15.8 
 
 Cellular tissue convertible into gelatin 1 '9 
 
 Albumen and colouring matter 2'2 
 
 Alcoholic extract, or ozmazome, with lactic acid and lactates 1 '8 
 
 Watery extract, with phosphate of soda 1'05 
 
 Phosphate of lime -08 
 
 100- 
 The inadvertent omission, on the part of M. Cruveilhier, oi fibrin as one of the proximate principles of mus- 
 cle, will serve to impress on the mind of the reader its importance as a constituent of that tissue, in which it 
 exists in greater abundance than in any other. 
 
 The substance called leucine, mentioned in the text, is a product resulting from the action of concentrated 
 sulphuric acid on muscular fibre, and therefore must not be regarded as previously existing in it.] 
 
 ^ As it is our intention to introduce, after Myology, an account of the Aponeuroses, we shall be content at 
 present with the general ideas that have been already stated regarding this important division of the fibrous 
 tissues. 
 
USES OF MUSCLES. 
 
 195 
 
 that is applied to the various levers represented by the component parts of the skeleton. 
 The movements produced are the result of that peculiar property possessed by the mus- 
 cles of shortening themselves, which is called muscular contractihiy {myotiliti). The 
 shortening of a muscle is termed its contraction, and the opposite state its relaxation. 
 
 Phenomena of Muscular Contraction. — During contraction the muscular fibres become 
 folded in a zigzag manner throughout their entire length ; the muscle itself becomes 
 hardened, and broader and thicker in proportion to the amount of shortening. There is 
 no oscillation in a muscular fibre during a normal contraction.* 
 
 The aponeuroses and the tendons take no part in the contraction ; they are entirely 
 passive. The degree of shortening of which the muscular fibre is susceptible cannot 
 be precisely determined ; as far as we know, the shortening, and, consequently, the ex- 
 tent of the resulting movement, is proportional to the length of the fibre. A distinction 
 should be drawn between the force and the velocity or rapidity of muscular contraction. 
 Again, the velocity is very different from the extent of motion : the latter depends upon 
 the length of the fibres ; the former has no connexion with it, but varies according to the 
 constitution of the individual, and is probably dependant on a more or less rapid influx 
 of nervous influence. 
 
 The muscular force is composed of a great number of elements. According to Borel- 
 li, an intrinsic and an effective farce may be distinguished in each muscle. The in- 
 trinsic force is that power which the muscular fibres would exert if they were in the 
 most favourable position for contraction : the effective force is measured by the result. 
 The estimation of the force of a muscle presupposes a knowledge, 1 . Of the number of 
 its fibres. 2. Of ther quality or constitution. 3. Of the nature of the lever upon which 
 it acts. 4. Of the angle of incidence of the muscle upon that lever ; and, 5. Of the angle 
 of incidence of the fibres with respect to the imaginary axis of the muscle. 
 
 1. Each muscular fibre, being distinct from those around it, may be considered as a 
 small power ; it may, therefore, be eeisily conceived that the greater the number of fibres 
 in any muscle, the more energetic will be its contraction. 
 
 2. The quality and constitution of the fibre, and the intensity of the stimulus, have no 
 less an influence upon the contractile force of a muscle than the number of its fibres. To 
 be convinced of this, it is sufficient to compare the energy of movement in an individual 
 excited by anger with that in one who is C2ilm. 
 
 3. The determination of the kind of levert represented by the bone upon which the 
 muscle acts, is a fundeimental point in studying muscular action. It is a law in mechan- 
 ics, that the power acts with greater effect in proportion as its arm of the lever exceeds 
 in length that of the resistance. The most common lever in the human body is that of 
 the third order, in which the power, being applied between the fulcrum and the weight, 
 is therefore most disadvantageously situated for action. 
 
 4. As far as regards energy of movement, the lever to which the power is applied is 
 as unfavourable as possible, because the muscles are generally inserted near the fulcrum. 
 
 * The observations of Rogerus tend to show that rapid contractions and relaxations are cotutantly takiiig 
 place in muscles, especially during their contraction. — (TV.) 
 
 " Be Peri)etua Fibrarum Muscularium Palpitatione," 1760. Fig. 103. 
 
 t A lever, in mechanics, signifies an inflexible rod capable of turning 
 round a point. The point upon which the lever turns is called the /ui- 
 crum if, figs- 103, 104, 105) ; the cause of motion is called the power (p) ; 
 and the obstacle to be surmounted is the resistance (r) ; the space be- 
 tween the fulcrum and the power is the power-arm of the lever ; the space 
 between the fulcrum and the weight is the resistance-arm of the lever. 
 There are three kinds of levers, distinguished by the respective arrange- 
 ment of the three parts : 1. A lever of the first order {fig. 103) has the ful- 
 crum between the power and the resistance. 2. A lever of the second or- 
 der (fig. 104) has the resistance between the fulcrum and the power. 3. 
 A lever of tlte third order {fig. 105) has the power between the resistance 
 and the fulcrum 
 
 Fig.lOi. 
 
196 MiULoGV, 
 
 But, as a sort of compensation, an advantage peculiar to animal mechanics, the motions 
 gain in velocity and extent what they lose in force, which, however, may still be obtain- 
 ed by an increase in the number of muscles, and of the fleshy fibres of each muscle. 
 Nevertheless, levers of the most favourable construction, and of the most advantageous 
 position, are met with in situations where considerable force is required ; as in the ar- 
 ticulation of the foot with the leg, presenting an example of a lever of the second order ; and 
 in the articulation of the head with the vertebral column, forming a lever of the first order. 
 
 The angle of incidence most favourable to the power is the right angle ; but in the hu- 
 man body, as the muscles are arranged in layers upon the bones which they are intend- 
 ed to move, they are for the most part inserted at very acute angles. Their incidence 
 would be still more unfavourable were it not for the enlargement of the articular ex- 
 tremities of the bones, which disturb the parallelism of the muscles. Besides, in certain 
 cases, the angle of incidence more or less approaches, or even attains to a right angle, 
 and is combined with an extremely advantageous lever, when such an arrangement is 
 required : a& in the articulation of the foot with the leg. 
 
 It is of importance to notice, in determining the action of a muscle, that its incidence 
 upon the bone varies at different periods during its action ; so that a muscle which is 
 eilmost parallel to the lever when it begins to contract, becomes perpendicular to it at a 
 given moment during that process. It maybe said that the momentum of a muscle occurs 
 at that period of its action when its perpendicular incidence gives it the utmost energy 
 of which it is capable : thus, the momentum of the action of the biceps femoris takes 
 place when the leg forms a right angle with the thigh. In a certain number of muscles 
 the momentum coincides with the commencement of action, such as the gastrocnemii 
 and the solei. In some muscles the angle of incidence remains the same throughout the 
 whole time of their action, and, consequently, they have no momentum : this is the case 
 with the deltoid. 
 
 The angle of incidence of the muscular fibres, with regard to the imaginary axis of 
 the muscle or the terminating tendon, involves a loss of power proportional to the amount 
 of the angle. In some muscles the aponeuroses form a continuation of the fleshy fibres ; 
 in others, the angle of incidence of the muscular fibre is so acute that it may be left out 
 of consideration. 
 
 Estimation of the Action or Uses of the Muscles. — Since the contraction of a muscle con- 
 sists in its shortening, it follows that its action may be determined, a priori, from a 
 knowledge merely of its attachments and direction. It may also be ascertained experi- 
 mentally, by placing a limb in such a position that the muscfe in question shall be per- 
 fectly relaxed. As the same muscle generally performs several uses, it is necessary to 
 place the limb in several different positions, so as to determine those in which the mus- 
 cle becomes relaxed. Let us take, for example, the glutaeus maximus. If we desire to 
 relax this muscle completely, it is necessary, 1. To extend the thigh upon the pelvis. 
 2. To abduct it. 3. To rotate it outward : hence it follows that the glutaeus maximus 
 is at once an extensor, an abductor, and a rotator outward of the thigh. As a counter- 
 proof, the limb must be placed in such a condition that the muscle becomes completely 
 stretched. The successive positions in which a muscle becomes stretched will be the 
 very reverse of those which the limb assumes during the contraction of the muscle. 
 Thus, the glutaeus maximus is slightly stretched by rotation inward, more so by adduc- 
 tion, and most completly by flexion of the thigh upon the pelvis. 
 
 In determining the action of a muscle that is reflected over any angle of a bone, it is 
 necessary to put out of consideration all that portion of the muscle intervening between 
 its origin and its angle of reflection, and to suppose the power to operate directly from 
 the latter points. 
 
 The action of sphincter muscles is to close the orifices around which they are placed. 
 A curvilinear muscle assumes a rectilinear direction at the very commencement of its 
 action. 
 
 The insertions of a muscle are neither equally fixed nor equally movable. The fixed 
 • point of a muscle is that extremity which remains immovable during contraction ; but, in 
 certain cases, the fixed may become the movable point : this must be taken into consider- 
 ation in determining the action of a muscle. The fixed point is most commonly that 
 which is nearest to the trunk. But, with few exceptions, it is never completely station- 
 ary ; and since a muscle would lose much of its power when acting between a movable 
 and an imperfectly fixed point, it is necessary that the latter should be kept as immova- 
 ble as possible by the contraction of other muscles. These consecutive contractions are 
 often very extensive, and should be familiar both to the physician and the physiologist. 
 
 When a muscle passes over several articulations, it moves them all in succession, 
 commencing with the one nearest to the movable insertion. 
 
 Those muscles which concur in producing the same motion are called congenerous ; 
 those which execute opposite movements are termed antagonists : thus all the flexor 
 muscles of any region are congenerous, and they are antagonists to the extensors. 
 
 Two muscles may be congenerous at one time, and act as antagonists at another : 
 when they contract simultaneously, their individual and opposite effects are destroyed. 
 
PREPARATION, ETC., OP MUSCLES. 197 
 
 and a common and intermediate effect results ; thus, when the flexor carpi ulnaris, which 
 is both an adductor and a flexor, acts in conjunction with the extensor carpi ulnaris, 
 which is an adductor and extensor, the hand is neither flexed nor extended, but is mere- 
 ly adducted. We shall constantly have occasion to notice this arrangement, which ap- 
 pears to me calculated to give much greater precision of motion than if two perfectly 
 congenerous muscles had been employed. 
 
 There are also certain compound motions, which are, as it were, the results of two 
 different movements ; thus, when the flexors and the adductors of the thigh act simul- 
 taneously, the femur passes in the intermediate direction. It is from this kind of com- 
 bination that the movement of circumduction is produced by the action of the four orders 
 of muscles situated at the extremities of the antero-posterior and transverse diameters 
 of the joint. These four orders of muscles are known by the names oijlexors, extensors, 
 adductors, and abductors. 
 
 Lastly, muscles may contract without producing any motions, as when antagonist 
 muscles act with equal energy. The result of such a simultaneous contraction is an 
 active immobility or tonic movement, as the older WTiters termed it, which is of very great 
 importance. 
 
 Preparation of Muscles. 
 
 Dissection. — The end to be attained in the dissection of a muscle is to isolate it accu- 
 rately from all the surrounding parts, leaving only those connexions which are compat- 
 ible with that object. Since, however, it is sometimes impossible to preserve the rela- 
 tions, and at the same time isolate the muscle, it then becomes necessary to be provided 
 with two preparations for the demonstration or study of the same muscle. 
 
 In order to isolate a muscle, the surrounding cellular tissue, which often forms a very 
 adherent sheath, must be removed ; and to do this completely, 1. Make a section of the 
 skin parallel to the fibres of the muscle, deep enough to reach the muscle through the 
 sheath; 2. As soon as the flap of skin can be grasped by the hand, stretch and separ- 
 ate it from the muscle by cutting with the scalpel in the angle formed by these two 
 parts ; 3. When the superficial surface is exposed, proceed to separate the deep surface, 
 preserving as much as possible all its important relations ; 4. Then dissect the extrem- 
 ities, marking out their limits with the greatest care. 
 
 In the study of the muscular system, great importance should be attached to the choice 
 of subjects. Robust and tolerably fat subjects are best adapted for this purpose. 
 
 Preservation of Muscles in Liquids. — Alcohol, oil of turpentine, a mixture of equal parts 
 of these, or solutions of the bichloride of mercury, or persulphate of iron, may be em- 
 ployed for the preservation of muscles, though they alter many of their properties, such 
 as their colour, consistence, &.c. 
 
 Preparations by Desiccation. — As this kind of preparation requires a peculiar method, 
 we refer to the special treatises upon anatomical preparations for an account of them. 
 (Vide the works of MM. Marjolin arid Louth.) 
 
 Order of Description of the Muscles. 
 Before passing to the description of the particular muscles, it is necessary to deter- 
 mine in what order they shall be studied. Galen divided the body for this purpose into 
 regions, and described the muscles of each in their order of super-imposition. In place 
 of this arrangement, which is purely topographical, Vesalius substituted a physiological 
 one, founded upon a consideration of the uses of the muscles. This order was adopted 
 by Winslow, who named the different muscular regions in the following manner : 3fus- 
 cles which move the shoulder upon the trunk ; muscles which move the arm upon the scapula, 
 &c. Albinus revived the method pursued by Galen, and divided the muscles into forty- 
 eight regions in the male and forty-six in the female. He was followed by Sabatier, and 
 by Vicq-d'Azyr, who brought the arrangement to perfection by establishing some sub- 
 divisions in the groups formed by Albinus. Thus modified, it has been adopted by most 
 modem anatomists. It is evidently preferable in many respects, since it is essentially 
 anatomical, and is best calculated to exhibit the relations of the different muscles and 
 regions. In regard, also, to economy of subjects and facility of dissection, it has many 
 advantages over the physiological order, with which, however, in many regions it may 
 be made to coincide. We shall, therefore, adopt this arrangement, modifying it so far 
 as to permit all the muscles to be dissected upon one subject ; and, aft;er having descri- 
 bed all the muscles according to their topographical relations, we shall give a table in 
 which they will be grouped in a physiological order. 
 
198 
 
 MYOLOGY. 
 
 MUSCLES OF THE POSTERIOR REGION OF THE TRUNK. 
 
 TTie Trapezius. — Latissimus Dorsi and Teres Major. — Rhomboideus. — Levator AnguR 
 Scapula. — Serrati Postici. — Splenius. — Posterior Spinal Muscles. — Complexus. — Iriter- 
 spinalis Colli. — Recti Capitis Postici, Major et Minor. — Obliqui Capitis, Major et Minor, 
 — General View and Action of the Posterior Spinal Muscles. 
 
 The muscles situated on the posterior region of the trunk form several layers, which, 
 proceeding from the skin to the bones, consist, on either side, of the trapezius, the latis- 
 simus dorsi and teres major, the rhomboideus and levator anguli scapulae, the serrati 
 postici, superior and inferior, the splenius, the long muscles of the back, viz., the sacro- 
 lumbalis and longissimus dorsi ; the transversalis colli and the complexus (which I re- 
 gard as two series of accessory fasciculi to the longissimus dorsi) ; the complexus ma- 
 jor, the inter-spinales colli, the recti capitis postici, major et minor, and the obliqui 
 .capitis, major et minor.* 
 
 The Trapezius. 
 Dissection. — 1. Render the muscle tense by placing a block under the chest ; 2. Make 
 an incision through the skin from the occipital protuberance to the twelfth dorsal verte- 
 bra, and another horizontally from the seventh cervical vertebra to the external end of 
 the clavicle ; 3. Reflect the two flaps, together with the cellular membrane adhering in- 
 timately to the muscle ; 4. Dissect very carefully the insertions into the occipital bone, 
 which consist of a very thin aponeurosis closely united to the skin. 
 The trapezius (cucuUaris, Alhinus, a, figs. 106, 113), the most superficial muscle on the 
 Fig. 106. posterior region of the trunk, covers 
 
 the nape of the neck and the back. 
 It is a broad triangular, rather than 
 trapezoid muscle, thick in the mid- 
 dle, thin and elongated at its supe- 
 rior and inferior angles. 
 
 Attachments. — It arises from the 
 spinous processes of all the dorsal 
 and the seventh cervical vertebrae, 
 from the corresponding supra-spi- 
 nous ligaments, from the posterior 
 cervical ligament (ligamentum nu- 
 chae;, and from the internal third of 
 the superior occipital line, and is in- 
 serted into the entire length of the 
 spine of the scapula, into the poste- 
 rior border of the acromion, and into 
 the external third of the posterior 
 border of the clavicle. The fixed 
 attachments or origins of this mus- 
 cle present, 1. A broad, semi-ellipti- 
 cal aponeurosis, which, when united 
 to the one on the opposite side, forms 
 an ellipse, occupying the space be- 
 tween the sixth cervical and the 
 third dorsal vertebrae ; 2. A very thin 
 fibrous lamina, not having the ordi- 
 nary shining appearance of an apo- 
 neurosis, which is firmly adherent to 
 the skin, and forms the truncated 
 occipital angle of the muscle ; 3. A 
 great number of tendinous fibres, 
 constituting all those attachments 
 to the vertebrae that are independ- 
 ent of the two preceding aponeuro- 
 ses. From these origins all the fleshy 
 fibres proceed outward, the inferior fibres from below upward, the superior from above 
 downward, and from behind forward, and the middle ones horizontally. They terminate 
 in the following manner : the lower or ascending fibres are collected together, and at- 
 tached to a triangular aponeurosis, which, gliding over the small facette at the internal 
 extremity of the spine of the scapula, is inserted into the tubercle immediately connect- 
 ed with it ; the middle or horizontal fibres terminate at the posterior border of the spine 
 of the scapula, by tendinous fibres which are very distinct, especially towards the acro- 
 
 * [The transverso-spinalis muscle includes the semi-spinalis colli, the semi-spinalis tlorsi, and the multifidiu 
 iminse of Alhinus.] 
 
THE LATISSIMUS DORSI AND TERES MAJOR. 189 
 
 mion ; the upper or descending fibres are inserted into the convex portion of the posterior 
 border of the clavicle, many of them being also attached to the upper surface of that bone. 
 
 Relations. — The trapezius is covered by the skin, from which it is separated by an 
 aponeurotic lamina, except at the upper part, where the muscle and integuments are 
 intimately adherent. It covers the complexus, splenius, rhomboideus, and levator an- 
 guli scapulae, in the neck ; and the serratus posticus superior, the supra-spinatus, the pos- 
 terior spinal muscles, and the latissimus dorsi, in the back. The most important rela- 
 tions of this muscle are those of its superior and external or occipito-clavicular margin : 
 tms forms the posterior boundary of the supra-clavicular triangle, which is limited in 
 front by the stemo-mastoid muscle, and below by the clavicle. It should be observed 
 in reference to the indications regarding the supra-clavicular space, furnished by this 
 margin of the trapezius, that it sometimes advances as far as the middle of the clavicle, and 
 has even been observed to become blended with the posterior edge of the stemo-mastoid. 
 
 Action. — 1. The upper or descending portion elevates the clavicle, and, consequently, 
 the apex of the shoulder ; but if the shoulder be fixed, this portion of the muscle inclines 
 the head to one side and extends it, and, moreover, rotates it, so that the face is turned 
 to the opposite side. 2. The middle or horizontal portion carries the shoulder back- 
 ward, but, from the obliquity of the spine of the scapula, it also rotates that bone, so that 
 the apex of the shoulder is carried upward. 3. The lower or ascending portion draws 
 the posterior costa of the scapula inward and downward ; and, by a species of rotation, 
 which was alluded to when treating of the scapulo-clavicular articulations, also elevates 
 the apex of the shoulder. 4. When the whole of the muscle contracts at once, the scap- 
 ula is drawn inward, and the apex of the shoulder is raised. 
 
 The Latissimus Dorsi and Teres Major. 
 
 Dissection. — 1. Render the latissimus dorsi tense by the same means as were employ- 
 ed for the trapezius, and also by withdrawing the arm from the side. 2. Make an incis>- 
 ion in the median line from the tenth dorsal vertebra to the sacrum, and another trans- 
 versely from the same vertebra to the posterior border of the axilla, dividing in the lat- 
 ter incision a fibro-cellular membrane, which adheres very firmly to the fleshy fibres. 
 3. Dissect the humeral insertion very carefully, and at the same time prepare the teres 
 major, which is very intimately related to this extremity. 
 
 The Latissimus Dorsi. 
 
 The latissimus dorsi (b,fig. 106, p,figs. 109, 110) occupies the lumbar and part of the 
 dorsal region, and the posterior border of the axilla. It is the broadest of aU the mus- 
 cles, and shaped like a triangle, having its inferior angle truncated, and its upper and 
 external angles considerably elongated. 
 
 Attachments. — It arises from the spinous processes of the last six or seven dorsal, of 
 all the lumbar, and of the sacred vertebrae, from the posterior third of the crest of the 
 ilium, and from the last four ribs, and is inserted into the bottom of the bicipital groove 
 of the humerus, not into its posterior border. 
 
 Its origin from the crest of the ilium and from the vertebrae is effected through the 
 medium of a triangular aponeurosis, narrow and thin above, broad and very strong be 
 low, where it is blended with the aponeuroses of the serratus posticus inferior and ob 
 liquus intemus abdominis, and with the posterior layer of the aponeurosis of the trans- 
 versus abdominis. This aponeurosis assists in forming the sheath of the sacro-lumbalis, 
 longissimus dorsi, and trans verso-spinalis. The costal origins consist of fleshy tongues 
 or digitations, which are interposed between similar processes of the external oblique. 
 From this threefold origin the fleshy fibres proceed in the following manner : the upper 
 pass horizontally, the middle are directed obliquely, and the lower vertically upward ; 
 they all converge, so as to form a thick fasciculus, directed towards the inferior angle 
 of the scapula, from which it often receives some accessory fibres. The muscle is then 
 twisted upon itself, so that the inferior or vertical fibres become first anterior and then 
 superior, while the superior or horizontal fibres become first posterior and then inferior. 
 This torsion may perhaps be intended to prevent displacement of the fibres. They all 
 terminate in a flat quadrilateral tendon, which is inserted into the bottom of the bicip- 
 ital groove, above the insertion of the tendon of the pectoralis major. This tendon fur- 
 nishes a fibrous expansion continuous with the fascia of the arm, and also a band which 
 extends to the lesser tuberosity of the humerus. 
 
 Relations. — This muscle is covered by the skin (from which it is separated by a close- 
 ly-adherent fibro-cellular sheath), and by the inferior angle of the trapezius. It covers 
 the posterior spinal muscles, the serratus posticus inferior, the external intercostals, the 
 serratus magnus, the lower angle of the scapula, the rhomboideus, and, lastly, the teres 
 major, by which muscle it is itself covered in its turn. Its external margin is in relation 
 with the posterior border of the external oblique, from which it is separated below by a 
 small triangular interval. The upper part of the external margin, together with the teres 
 major, forms the posterior border of the axilla ; and from the same margin a muscular fasci- 
 culus occasionally extends beneath the axilla to the lower edge of the pectoralis major. 
 
mtfO MYOLOGY. 
 
 The Teres Major. 
 
 This muscle (c c,Jig. 106), which, both in its uses and its anatomical arrangements, 
 should be considered an accessory to the latissimus dorsi, is situated behind the shoulder. 
 
 Attachments.— It arises from the quadrilateral surface, situated at the inferior angle of 
 the scapula, to the outer side of the infra-spinous fossa, and is inserted into the josterior 
 border of the bicipital groove. The scapular attachment consists of short tendinous 
 fibres, some of which are fixed directly to the bone, and some into the fasciae, which 
 separate this muscle from those of the infra-spinous and subscapular fossae. The fleshy 
 fibres arising from these different attachments form a thick fasciculus, flattened from be- 
 fore backward, not cylindrical, and about two or three fingers in bieadth, which is direct- 
 ed outward and upward, and becomes slightly twisted, so as to be inserted by a broad 
 and flat tendon into the posterior border of the bicipital groove. 
 
 Relations. — The latissimus dorsi at first covers its scapular extremity, and then, turn- 
 ing round its lower edge, becomes anterior to it. The tendon of the latissimus dorsi is, 
 therefore, applied to the anterior surface of the tendon of the teres major ; but since the 
 former is attached to the bottom, and sometimes even to the anterior border of the bi- 
 cipital groove, and the latter to the posterior border of the same groove, they are separ- 
 ated at their insertions by an interval, in which there is almost always a synovial mem- 
 brane, and which forms a true cul-de-sac below, for the lower margins of the two tendons 
 are blended together. 
 
 The posterior surface of the teres major is covered by the skin, from which it is sep 
 arated on the inside by the latissimus dorsi, and externally by the long head of the tri- 
 ceps. Its anterior surface is in relation with the subscapularis, the coraco-brachialis, 
 the short head of the biceps, the brachial plexus, the axillary vessels, and the cellular 
 tissue of the axilla. Its upper margin is at first in contact with the teres minor, from 
 which it is separated above by the long head of the triceps ; its lower margin forms, in 
 conjunction with the latissimus dorsi, the posterior border of the axilla. 
 
 Action of the Latissimus Dorsi and Teres Major. — The latissimus dorsi adducts the 
 arm, rotates it inward, and at the same time draws it backward (hence its name, ant 
 scalptor). When only the upper or horizontal fibres contract, the arm is carried inward 
 and backward ; when the lower fibres act alone, it is carried downward. 
 
 The uses of the teres major are precisely similar to those of the latissimus dorsi, to 
 which it is congenerous and accessory, and with which it is always associated in ac- 
 tion, drawing the humerus inward, backward, and downward. When the humerus is 
 the fixed point, the latissimus dorsi raises the trunk, and with the greater facility, be- 
 cause it is attached to the ribs, the spine, and the pelvis. In consequence of its costal 
 attachments, the latissimus dorsi is a muscle of inspiration ; and it should be observed, 
 that the direction of its fibres, which is almost perpendicular to the ribs, enables it to 
 act with great power. 
 
 The Rhomboideus. 
 
 Dissection. — Divide the trapezius by an incision extending from the third dorsal ver- 
 tebra to the lower angle of the scapula ; dissect back the flaps, taking care to remove a 
 fibro-cellular layer which adheres closely to the trapezius. 
 
 The rhomboideus {d d, fig. 106), situated in the dorsal region, on the posterior aspect 
 of the trunk, approaches closely to the form of a rhomboid or lozenge ; it is broad and 
 thin, but thicker below than above, and is almost always divided into two parts. 
 
 Attachments. — It arises from the bottom of the ligamentum nuchae, from the spinous 
 processes of the seventh cervical and five superior dorsal vertebrae, and from the corre- 
 sponding interspinous ligaments, and is inserted into all that part of the posterior costa 
 of the scapula situated below its spine. The spinal or internal attachments consist of 
 tendinous fibres, the most inferior of which are the longest. From these points the 
 fleshy fibres proceed, parallel to each other, downward and outward, to a very thin ten- 
 don, which runs along the posterior costa of the scapula, but only adheres to it above 
 and below : the greater number of fibres are inserted into the lower angle of the scapula 
 by a very strong tendon, which forms the principal attachment of the muscle, and to 
 wliich the tendon mentioned above is merely subordinate. The upper part of this mus- 
 cle {e,fig. 103), which arises from the hgamentum nuchae and the seventh cervical ver- 
 tebra, is inserted by itself opposite the spine of the scapula. It is distinct from the re- 
 mainder of the muscle, and from this fact Vesalius, Albinus, and Scemmering gave it 
 the name of rhomboideus minor or superior. 
 
 Relations. — This muscle is covered by the trapezius, the latissimus dorsi, and the 
 skin. It covers the serratus posticus superior, part of the posterior spinal muscles, the 
 ribs, and the intercostal muscles. 
 
 Action. — ^The rhomboid raises the scapula and draws it inward. As it acts principal- 
 ly upon the lower angle of that bone, it rotates it in such a manner that the anterior 
 angle, and, consequently, the apex of the shoulder, is depressed. It assists the trape- 
 zius in carrying the entire shoulder inward, and is also associated with the upper fibres 
 
THE SERRATI POSTICI. 201 
 
 of the same muscle in raising that part ; hut, on the other hand, it antagonizes the tra- 
 pezius by depressing the apex of the shoulder. 
 
 The Levator Anguli Scapulcs. 
 
 Dissection. — Detach the trapezius from the spine of the scapula with care ; divide the 
 upper part of the sterno-mastoid, so as to expose the transverse processes of the three 
 or four superior cervical vertebrae. 
 
 The levator anguli scapula (levator scapulae, Alhinus, f,figs. 106, 110, 113, 114), situ- 
 ated at the posterior and lateral part of the neck, is an elongated bundle, having its up- 
 per portion flattened from without inward, and divided into three or four fasciculi, while 
 the lower part is flattened from behind forward. 
 
 Attachments. — It arises from the posterior tubercles of the transverse processes of the 
 three or four superior cervical vertebrae, externally to the splenius, and behind the sca- 
 lenus posticus ; it is inserted into the superior angle of the scapula (whence its name), 
 and into all that portion of its internal costa situated above the spine. 
 
 The cervical attachments of this muscle consist of four tendons, to which succeed an 
 equal number of fleshy fasciculi, at first distinct, but afterward united into one bundle, 
 which proceeds downward, backward, and outward, and spreads out to be inserted into 
 the scapula by short aponeurotic fibres. 
 
 Relations. — It is covered by the trapezius, the sterno-mastoid, and the skin ; and it 
 lies superficially to the splenius, the sacro-lumbalis, the transversalis colli, and the ser- 
 ratis posticus superior. 
 
 Action. — When its upper attachment is fixed, this muscle carries the posterior angle 
 of the scapula upward and forward, and, consequently, rotates that bone, so as to depress 
 the apex of the shoulder. It conspires with the rhomboid and the trapezius in elevating 
 the entire shoulder, and with the rhomboid in depressing its apex, in this respect acting 
 as an antagonist to the trapezius. When the fixed point is below, which must be very 
 rarely, it inclines the neck backward and to its own side. 
 
 The Serrati Postici. 
 
 These are two in number, a superior and an inferior. 
 
 Dissection. — 1. To expose the superior muscle, divide and reflect the trapezius and the 
 rhomboid, and draw the scapula forward ; 2. To display the inferior, raise the latissimus 
 dorsi with great care, as its deep aponeurosis is blended with that of the serratus posticus 
 inferior ; 3. Preserve the thin aponeurosis extending between the two serrati muscles.* 
 
 1. The serratus posticus superior is situated at the upper and back part of the thorax, 
 and is of an irregularly-quadrilateral figure. 
 
 Attachments. — It arises from the ligamentum nuchae and the spinous processes of the 
 seventh cervical and of the two or three upper dorsal vertebrae, and is inserted into the 
 upper borders of the second, third, fourth, and fifth ribs. The vertebral attachment con- 
 sists of a very thin aponeurosis, the fibres of which are parallel, and inclined downward 
 and outward. From this aponeurosis, which constitutes at least the inner half of the 
 muscle, the fleshy fibres proceed in the same direction, and almost immediately divide 
 into four digitations, which are inserted into the ribs by means of short tendinous fibres. 
 The superior digitation is attached near the angle of the corresponding rib, and each of 
 the others at successively greater distances from it. 
 
 2. The serratus posticus inferior (lumbo-costalis, Chaussier, g, fig. 106) is also of an ir- 
 regularly-quadrilateral form, and is situated at the lower part of the back and the upper 
 part of the loins. It arises from the spinous processes of the two lower dorsal and three 
 upper lumbar vertebrae, and is inserted into the inferior borders of the last four ribs. The 
 vertebral or internal attachment consists of an aponeurosis similar to that of the prece- 
 ding muscle, but its fibres have an inverse direction, i. e., obliquely outward and upward. 
 From this aponeurosis, which forms the internal half of the muscle, the fleshy fibres pro- 
 ceed in the same direction, and divide into four flat digitations, progressively decreasing 
 in size from above downward, which are inserted into the ribs by means of tendinous 
 laminae, the superior digitation near the angle of its corresponding rib, and the others, 
 successively, farther beyond it. 
 
 Relations. — These two muscles have certain relations in common, and there am some 
 peculiar to each. They both cover the longissimus dorsi, the sacro-lumbalis, the trans- 
 verso-spinalis, the ribs, and the corresponding intercostal muscles. The superior is cov- 
 ered by the rhomboideus, the trapezius, and the serratus magnus, and covers the splenius 
 and transversalis colli. The inferior is covered by the latissimus dorsi, with the apo- 
 neurosis of which muscle its own aponeurotic lamina is so closely united that it is impos- 
 sible to separate them completely ; and it covers the posterior layer of the aponeurosis 
 of the transversalis. 
 
 Action. — Besides certain common uses, each muscle has its own peculiar action. One 
 
 * [This exceedingly thia and semi-transparent lamella has received the name of the vertebral aponewrotit 
 
 Sep A.P0NEUK0I.0OY.] 
 
 Cc 
 
202 MYOLOGY. 
 
 impoitant common use is, to retain in the vertebral groove those muscles of the back 
 which, from their extreme length, are the most liable to displacement. This effect is 
 produced by their fleshy portions rendering tense their aponeurotic expansions. 
 
 With regard to the actions proper to each, 1. The superior elevates those ribs into 
 which it is inserted, and is, consequently, a muscle of inspiration ; 2. The inferior, on 
 the other hand, is a depressor of the ribs, and, therefore, a muscle of expiration. 
 
 The Splenius. 
 
 Dissection. — Merely remove the trapezius, the rhomboid, and the serratus posticus su- 
 perior. 
 
 The splenius {i,Jigs. 106, 113, 114), so named because it has been compared to the 
 spleen {a■!T^v), is situated at the posterior part of the neck and upper part of the back. It 
 is a broad muscle, terminating in a point below, and dividing into two portions above. 
 
 Attachments. — It arises from the spinous processes of the four or five superior dorsal 
 and the seventh cervical vertebra, from the corresponding supra-spinous ligaments, and 
 also from the ligamentum nuchae, between the seventh and the third cervical vertebrae ; 
 it is inserted, 1. Into the transverse processes of the first, second, and often the third cer- 
 vical vertebrae ; 2. Into the external surface and posterior border of the mastoid process, 
 and the external third of the rough space beneath the superior semicircular line of the 
 occipital bone. The spinal attachments consist of tendinous fibres, the most inferior of 
 which are the longest. From these the fleshy fibres proceed obliquely upward and out- 
 ward, the lower being longer and more vertical, and form a broad, flat muscle, which is 
 much thicker externSly, and soon becomes divided into two portions : one smaller, infe- 
 rior and external ; the other much larger, superior and internal. The former is called 
 the splenius colli ; it is sometimes distinct, even from its origin, and soon subdivides 
 into two or three fasciculi, which terminate in as many tendinous processes, that are in- 
 serted into the atlas, the axis, and often into the third cervical vertebra. The fascicu- 
 lus proceeding to the atlas is usually the largest. The second, or the upper and internal 
 portion of the muscle, is connected with the head, and is called the splenius capitis. 
 
 Relations. — The splenius is covered by the trapezius (the rhomboid and the serratus 
 posticus superior intervening below), by the sterno-mastoid, and by the levator anguli 
 scapulae. It covers the complexus, the longissimus dorsi, the transversalis colli, and 
 the trachelo-mastoid. The levator anguli scapulae is in contact with its outer border, 
 and rests upon it above, the cervical insertions of the two muscles being blended togeth- 
 er ; below they are separated by the transversalis colli and sacro-lurabalis. The inter- 
 nal edge is very thin, and separated from the muscle of the opposite side by a triangu- 
 lar interval, in which the complexi are visible. 
 
 Actions. — The splenius extends the head, inclines it to its own side, and rotates it so 
 that the face is turned to the same*ide. This action of the splenius depends on its at- 
 tachments to the occipital bone, the mastoid process, and the atlas. By its insertions 
 into the second and third cervical vertebrae it tends to rotate these in the same direction. 
 When the two muscles act together, the head is drawn directly backward. The splenius 
 is therefore an extensor and rotator of the head and of the neck ; it assists in supporting 
 the head in the erect position, and prevents it from inclining forward in obedience to the 
 force of gravity. 
 
 The Posterior Spinal Muscles. 
 
 As these muscles are arranged in a peculiar manner, we shall adopt a method of de- 
 scription in some measure different from that which we have elsewhere employed. 
 
 The posterior spinal, or long muscles of the back (see Jig. 107), are three in number, 
 viz., the sacro-lumbalis, the longissimus dorsi, and the transverso-spinalis muscle. 
 
 These three muscles, which extend the entire length of the spine, form a very large 
 muscular mass, completely filling up the corresponding vertebral groove. This mass is 
 small at the lower part of the sacral groove, becomes much enlarged in the loins, then 
 diminishes in the back, and again acquires a considerable size in the neck. Chaussier 
 has given a description of them under the collective name of the sacrospinal muscle ; 
 and they have also been denominated the erector spina. 
 
 I shall describe the three muscles together ; but, in order to adopt some arrangement 
 in a matter so complicated, I shall divide them into three portions, viz., a lumbro-sacral, 
 a thoracic, and a cervical. 
 
 Ltimhro-sacral Portion of the Posterior Spinal Muscles. 
 Dissection. — 1. Render this portion of the muscle tense, by placing a block under the 
 abdomen. 2. Divide by a vertical incision the trapezius, splenius, rhomboideus, latis- 
 simus dorsi, and serrati postici ; reflect the divided portions inward and outward. A 
 young subject, from ten to twelve years of age, is best adapted for the study of these 
 muscles, from the facility with which the different fasciculi may be separated. For the 
 same reason, one that is much infiltrated with serum is preferable to one in which the 
 parts are dry. i - 
 
THE POSTERIOE SPINAL MUSCLES. 
 
 203 
 
 The lumbo-sacral portion is usually called the common m/iss of the sacro-lumbalis and 
 longissimus dorsi. It forms the fleshy part of the loins, and is called the fdlet in the low- 
 er animals : it is the most highly developed in man, in whom it exerts a constant and 
 powerful action during the erect posture : it appears to be the coimnon origin of the pos- 
 terior spinal muscles, whence the name of common mass : it fills up entirely the lumbo- 
 sacral groove, and even projects backward and laterally in robust subjects. 
 
 It is of small size in the sacral region, is much enlarged at the middle of the lumbar 
 region, at the upper part of which it again diminishes, so as to resemble two cones uni- 
 ted by their bases. 
 
 Attachments. — The common mass arises from the whole extent of the sacro-iliac 
 groove, and from the anterior surface and external border of an extremely strong apo- 
 neurosis, formed of parallel vertical fibres, and strengthened by a superficial layer direct- 
 ed obliquely. This aponeurosis of origin for the posterior spinal muscles {d,fig. 107) is in- 
 serted on the inside to the sacral ridge, to the summits of the spinous processes of the 
 lumbar and three lower dorsal vertebrae, and to the corresponding supra-spinous liga- 
 ments : on the outside, to the series of eminences representing the transverse processes 
 of the sacral vertebrae, and to the back part of the crest of the ilium : it gives attach- 
 ment to many of the fibres of the glutaeus maximus. It is short on the outside, and very 
 long on the inside, reaching in the latter direction to the middle of the dorsal region, un- 
 der the form of parallel and regular bands {d,fig. 107). 
 
 Arising from these different origins, the coiimion mass appears at first extremely sim 
 pie in its composition, consisting of fibres passing vertically upward. But if the aponeu- 
 rosis be detached from its spinal insertions, and turned outward, it will be seen that the 
 common mass is essentially composed of two portions : one internal and anterior, the 
 lumbosacral portion of the transverso-spinalis ; and the other external and posterior, the 
 lumio sacral portion of the sacro-lumbalis and longissimus dorsi. 
 
 1. The lumbosacral portion of the transverso-spinalis* occupies all the sacral groove, and 
 that part of the lumbar groove situated within the articular processes. It is perfectly 
 distinct in the loins, being separated from the common mass by loose cellular tissue trav- 
 ersed by vessels and nerves. It arises from the articular processes of the lumbar verte- 
 brae by flat tendons, directed obliquely inward and upward, and terminating upon the pos- 
 terior surface of the muscle : by the imion of their contiguous edges an aponeurosis is 
 formed, which is itself blended along one of its borders with the deep surface of the com- 
 mon aponeurosis of origin. From these tendons the 
 fleshy fibres arise, and having united into bundles, 
 terminate by other tendons at the spinous processes 
 of the vertebrae above. In the sacral region this 
 portion of the transverso-spinaUs is less distinct, but 
 it may be easily seen that it occupies the whole of 
 the sacral groove, and that the corresponding por- 
 tion of the aponeurosis of origin affords attachments 
 fo it alone. 
 
 2. The external and posterior portion of the com- 
 mon mass, or lumbosacral portion of the sacro-lumbalis 
 and longissimus dorsi, is entirely without the sacral 
 groove, but occupies that part of the lumbar groove 
 situated on the outer side of the articular processes. 
 
 It arises, 1. From all the lumbar portion of the com- 
 mon aponeurosis. 2. From an extremely strong ten- 
 don, which is attached to the posterior superior spi- 
 nous process of the ilium. 3. From the posterior s~ 
 fourth of the crest of the ilium, internally by tendi- 
 nous, and externally by muscular fibres. The thick 
 fleshy mass proceeding from these different origins 
 is disposed of in the following manner : the greater 
 part of the fibres pass directly upward to the dorsal 
 region, forming the proper commencement of the 
 sacro-lumbalis (a a, fig. 107). The remaining fibres 
 are directed forward, and are arranged into two sets 
 of bundles, one of which is inserted into the summits 
 of the transverse processes, forming the external or 
 transverse fasciculi ; and the other into the tubercles 
 of the articular processes, forming the internal or ar- 
 ticular fasciculi. These two sets of fibres constitute 
 the proper origin of the longissimus dorsi (d d, fig. 
 107). 
 
 Relations. — The common mass is covered behind 
 
 Fiff. 107. 
 
 [This corresponds to the inferior or lumbo-sacral fasciculi of the multifidus spinte,] 
 
204 MYOLOGY. 
 
 by the united aponeuroses of the latissimus dorsi and serratus posticus inferior, and by 
 the posterior layer of the aponeurosis of the transversalis ; in front, it corresponds to 
 the lumbar groove, the inter-transversales muscles of the loins, and the middle layer of 
 the aponeurosis of the transversalis, which separates it from the quadratus lumborum ; 
 on the inside, it corresponds to the spinous processes ; and on the outside, to the angle 
 of union between the posterior and middle layers of the aponeurosis of the transversalis. 
 In this way it is completely enclosed in an osteo-fibrous sheath. 
 
 Thoracic Portion of the Posterior Spinal Muscles. 
 
 The transverso-spinalis muscle may be completely isolated from the others in this 
 region. We have seen the distinction between the sacro-lumbalis and longissimus dorsi 
 commenced at the upper part of the lumbar region ; in the back they are completely sep- 
 arated by some loose cellular tissue and the posterior branches of the dorsal nerves and 
 vessels. 
 
 The thoracic portion of the sacro-lurnbalis (6 V, fig. 107) consists of a continuation of the 
 vertical or external fibres of the common mass ; as it proceeds upward it becomes more 
 and more slender, and is divided into a series of fasciculi, which are inserted succes.sive- 
 iy into the angles of the ribs, by means of tendinous prolongations, that extend for a 
 considerable distance upon the posterior surface of the muscle. It was the existence of 
 these aponeurotic processes, the contiguous edges of which are often united, that in- 
 duced Winslow to compare the muscle to a palm leaf In this manner the muscular 
 fasciculi are soon expended, terminating at about the sixth rib, but the muscle itself is 
 continued into the neck by means of accessory fibres, which may be exposed by turning 
 the muscle outward, sifter separating it from the longissimus dorsi (as at h') : twelve 
 long, thin tendons will then be seen to arise from the upper portion of the angles of the 
 twelve ribs, and to pass outward and upward : to these succeed fleshy fasciculi, which 
 terminate in aponeurotic processes, situated on their posterior surfaces, and having pre- 
 cisely the opposite direction. These accessory bundles (c c',Jig. 107; i,fig. 108) have 
 been very well described by Diemerbroek under the name ofcervicales descendens, and by 
 Steno under that of musculus accessorius ad sacro-lumbalem ; the four or five superior bun- 
 dles form the transversaire grele of Winslow, and the cervicalis descendens of Albinus. 
 
 The thoracic portion of the longissimus dorsi (e e', fig. 107) is larger than the preceding 
 muscle, to the inner side of which it is situated : it diminishes much less rapidly, because 
 the common aponeurosis {d) is extended in the form of bands upon its posterior aspect, 
 which afford attachment to additional fleshy fibres. This muscle is a continuation of the 
 internal or articular, and the external or transverse fasciculi, described as existing in 
 the lumbar region, and is itself divided into three orders of fasciculi, one external and two 
 internal. 1. The external or costal fasciculi form the continuation of the transverse bun- 
 dles of the lumbar portion of the muscle, and are inserted by very thin tendons into the 
 space between the angles of the ribs and the summits of the dorsal transverse processes 
 (e',fig. 107). 2. The first set of internal, or the spinous fasciculi, are inserted into the spi- 
 nous processes of the five or six superior dorsal vertebrae ; and as they arise from tendi- 
 nous bands attached to the summits of the spinous processes of the lower dorsal vertebrae, 
 and of that of the first lumbar vertebra, Winslow considered them as forming a separate 
 muscle, which he called le long epineux du dos (spinalis dorsi, /,^o'. 107). 3. The second 
 set of internal, or the transverse fasciculi, are a continuation of the articular fasciculi of the 
 lumbar region ; they constituie the principal termination of the longissimus dorsi, and 
 are attached by very long and thin tendons to the transverse processes of the dorsal 
 vertebrae. 
 
 The thoracic portion of the transverso-spinalis* (partly seen in^^. 108) is reduced to a 
 very narrow band, concealed by the longissimus dorsi : it arises by very long and delicate 
 tendons from the lower dors^ transverse processes, and is inserted by others equally 
 sinailar, long and slender, into the summits of the superior dorsal spinous processes, 
 some pale fleshy fibres connecting the two series of tendons. 
 
 Connexions. — The dorsal portion of the posterior spinal muscles entirely fills the dor- 
 sal groove, limited on the outer side of the angles of the ribs. They are covered by 
 several muscular layers, the nearest of which is formed by the two serrati postici and 
 their connecting aponeurosis, which completes the sheath enclosing the long muscles of 
 the back : they are, moreover, separated from the skin by the rhomboid, trapezius, and 
 latfssimus dorsi. 
 
 The Cervical Portion of the Posterior Spinal Muscles, the Transversalis Colli, and the 
 
 Trachelo-mastoidcus. 
 Cervical portion of the sacro-lumbalis, or cervicalis descendens. The sacro-lumbalis, 
 whose original fibres are found to terminate at and upon the sixth rib, is continued, by 
 means of its accessory fasciculi (c c',fig. 107), up to the transverse processes of the four 
 or five inferior cervical vertebrae (i,fig. 108), into the summits of which it is inserted by 
 very slender tendons. The number of these terminating fasciculi varies in a remarkable 
 
 * [This corresponds to the semi-spinalis do.rs-, and to the dorsal portion of the multifidus spinsn of Albinus ■• 
 
THE POSTERIOR SPINAL AND COMPI.EXUS MUSCLES. 205 
 
 manner. Indeed, the splenius, the transverscdis colli, the sacro-lumbalis, and even the 
 levator anguli scapulas, are so closely connected, that, upon examining their cervical in- 
 sertions only, these might all be ascribed to a single muscle. The cervical portion of 
 the sacro-lumbalis is covered by the levator anguli scapulae, and can only be exposed by 
 turning this muscle outward. 
 
 The cervical portion of the longissimus dorsi, or the transverscdis colli, and the tra- 
 chelo-mastoid. The extent of the longissimus dorsi is limited to the back ; its highest 
 internal or spinous fasciculus seldom reaches the spinous process of the first dorsal ver- 
 tebra : its highest external or costal fasciculus is attached to the second, sometimes even 
 to the fourth rib, and its highest transverse fasciculus is inserted into the transverse 
 process of the first dorsal vertebra. In some very rare cases, a few internal fasciculi 
 reach the cervical vertebrae : I have seen one of them terminate by becoming attached 
 both to the transverse process of the third cervical vertebra and to the complexus. The 
 longissimus dorsi is, however, prolonged by accessory fasciculi as far as the third cervi- 
 cal vertebra. These fasciculi can only be identified by their direction (for they can never 
 be completely separated from this muscle) : they form a distinct muscle, known as the 
 transverscdis colli (transversalis cervicis, Albinus, g g,fig. 107). 
 
 By reflecting outward the upper part of the longissimus dorsi, they may be exposed, 
 varying in number, and arising from the summits of the transverse processes of the third, 
 fourth, fifth, sixth, and sometimes seventh and eighth dorsal vertebrae, by long, thin ten- 
 dons, and inserted by other tendons into the posterior tubercles of the transverse pro- 
 cesses of the five inferior cervical vertebras {I, fig. 108) : the transversalis colli is covered 
 by the longissimus dorsi, the splenius, and levator anguli scapulae, and rests upon the 
 trachelo-mastoid and complexus. 
 
 The trachelo-vtastoideus (complexus minor, i i, fig. 107) may be regarded as another 
 accessory muscle to the longissimus dorsi, which it continues up to the head. In order 
 to expose its origin, the transversalis colli must be reflected outward (as in fig. 107). 
 It arises from the angles between the transverse and articular processes of the four in- 
 ferior cervical vertebrae, by four small tendons, or sometimes by a continuous aponeu- 
 rotic plane. From thence the fibres proceed upward, and form a small muscle, which is 
 inserted into the mastoid process, in a small furrow to the inside of the digastric groove. 
 This small muscle is almost always interrupted by a tendinous intersection near its 
 mastoid insertion. 
 
 The cervical portion of the transverso-spinalis.* While the preceding muscles present 
 only a few fasciculi in the neck, the transverso-spinalist undergoes an enlargement in 
 this region, so as to occupy the entire cervical groove (a and b,fig. 108). In camivora, 
 this portion of the muscle is enormously developed (much more so than in man), in con- 
 sequence of those animals using the head and neck in seizing or struggling with prey. 
 In mammalia, as in man, the dorsal portion of the transverso-spinalis is, as it were, but 
 a rudiment in the lumbo-sacral region ; the muscle is larger in man than in other animals, 
 on account of his erect posture. Albinus described the enlarged cervical portion as a 
 separate muscle, viz., the spinalis cervicis. 
 
 In the neck, as in the other regions, the transverso-spinalis is a collection of super- 
 imposed fasciculi, which arise from the transverse processes of the five or six upper 
 dorsal, and from the articular processes of the five lower cervical vertebrae, and are in- 
 serted into the spinous processes of the six lower cervical vertebrae : the highest and the 
 largest fasciculus is attached to the axis. This muscle, which would have been much 
 better named articvio-spinalis, is composed of several layers of fasciculi, placed one above 
 the other, and extending from the whole length of the articular processes and laminae 
 of the vertebrae below to the whole length of the spinous processes and laminae of the 
 vertebrae above. The length of these layers diminishes progressively from the more 
 superficial {a, fig. 108) to the deep-seated ones (6) ; the latter extend only from one ver- 
 tebral lamina to another, and might be considered as proper muscles of the laminae, and 
 not as a part of the transverso-spinalis muscle. The most superficial layer is composed 
 of radiating fasciculi, diverging from one articular process to the summits of several of 
 the spinous processes. 
 
 The Complexus. 
 
 Dissection. — ^Divide the splenius perpendicularly to the direction of its fibres, and re- 
 flect the two parts upward and downward ; turn outward the upper portions of the lon- 
 gissimus dorsi, the transversalis colli, and the trachelo-mastoid {see fig. 107). 
 
 The complexus {I, fig. 107) is situated beneath the splenius at the posterior part of the 
 neck and upper part of the back. It is a flat muscle, broad above, but terminating in a 
 point below. 
 
 Attachments. — It arises, 1. From the transverse processes of the five or six superior 
 
 * If we were to follow the order of super-imposition rigorously, the complexus should be described before 
 this muscle, which cannot be brought into view until the former is removed. 
 
 t [This portion of the transverso-spinalis corresponds to the semi-spinalis colli (a, fig. 108), and the cervj 
 cal fasciculi (6) of the niultifidus spins of Albinus. 1 
 
206 MYOLOGY. 
 
 dorsal vertebrae ; 2. From the articular tubercles and the angular depression formed be- 
 tween them and the transverse processes of the four inferior cervical vertebrae ; 3. Some- 
 times from the spinous processes of the seventh cervical and two upper dorsal vertebrae : 
 it is inserted upon the side of the external occipitd crest into the inner half of the rough 
 space comprised between the two semicircular lines. The origins of this muscle con- 
 sist of tendons, from which the inferior fleshy fibres pass vertically upward, the superior 
 ones obliquely inward and upward, becoming graduaUy shorter and more nearly horizon- 
 tal. The muscular fibres are interrupted by some very remarkable tendinous intersec- 
 tions. Thus, on the inside, the fleshy fasciculus arising from the sixth, fifth, and fourth 
 dorsal vertebrae, gives origin to a tendon, which proceeds along the inner edge of the 
 muscle, and, at the distance of an inch and a half or two inches, becomes the origin of 
 another fleshy fasciculus, which is attached to the side of the occipital crest ; hence the 
 name of biventer cervicis, given by Eustachius to the whole complexus, and by Albinus to 
 this inner portion only (m, fig. 107). More externally, there is another flat tendon ex- 
 tending along the posterior surface of the muscle, from the outer edge of which an apo- 
 neurotic intersection passes in a zigzag course obliquely outward and upward. It is not 
 uncommon to find another small digastric fasciculus with a separate tendon, on the an- 
 terior surface of the muscle. 
 
 Relations. — The complexus is covered by the trapezius, splenius, longissimus dorsi, 
 transversalis colli, and trachelo-mastoid, and covers the transverso-spinalis and the recti 
 and obliqui capitis. Its inner edge is separated from the muscle of the opposite side by 
 a considerable quantity of adipose tissue, and by a prolongation of the ligamentum nuchae. 
 
 The Inter-spinales Colli. 
 
 The inter-spinales muscles are distinct in the neck oidy. It is generally admitted that 
 there are five pairs, the first of which extends between the axis and the third cervical 
 vertebra, and the last between the seventh cervical and first dorsal vertebras. They are 
 small quadilateral muscles, extending from one of the borders of the groove in the spinous 
 process below to the corresponding lip of the next process above. Externally, they are 
 in relation with the transverso-spinalis, and are separated from each other internally by 
 cellular tissue and an aponeurotic lamina. 
 
 Fig. 108. The Recti Capitis Posticiy Major and Minor. 
 
 The rectus capitis posticus major {e,fi^. 108) may be regarded as an 
 axoido-occipital, and the rectus minor (d) as an atloido-occipital inter-spi- 
 ndis muscle. They both arise tendinous, the smaller from the tubercle 
 on the posterior arch of the atlas, and the greater from the superior 
 tubercle of the spinous process of the axis (2) ; and, increasing in size, 
 they both pass obliquely upward and outward. The rectus major, 
 ^h which is much the larger and more oblique, is inserted to the outer 
 side of the inequalities situated below the inferior semicircular line 
 of the occipital bone ; the rectus minor is inserted to their inner side. 
 The name of recti is not, therefore, very appropriate, for both of them 
 (but more especially the larger one) are directed obliquely ; but they 
 are so called in contradistinction to two neighbouring muscles which 
 are much more oblique. The obliquity of these muscles (by increas- 
 ing their length) allows of more extended movements, and, at the 
 same time, enables them to assist in rotating the head. 
 
 Tht Ohliquus Capitis Major or Inferior^ and Obliquus Minor or Superior. 
 
 The ohliquus major or inferior (/, fig. 108), as far as its insertions are concerned, may 
 be called the axoido-atloid spino-transversalis ; it resembles, in fact, a thick fasciculus of 
 the longissimus dorsi. The obliquus minor or superior {g) may, for the same reason, be 
 called the atloido-occipital transverso-spinalis, resembling a thick fasciculus of that mus- 
 cle. The ohliquus major arises from the apex of the spinous process of the axis, on the 
 outer side of the rectus major (c), and above the transverso-spinalis (i. c, the semi-spi- 
 nalis colli and multifidus spinas conjoined, a and h) ; it forms a thick, cyhndriccd bundle, 
 passes almost horizontally outward, and is inserted behind and below the transverse 
 process of the atlas, which is excavated for this purpose. It is the axoido-atloideus of 
 Chaussier. The ohliquus minor (atloido-sub-mastoideus) arises by some very long tendi- 
 nous fibres from the upper part of the transverse process of the atlas, proceeds at an 
 angle of about 45° towards the occipital bone, into which it is inserted not far from the 
 mastoid process, by some tendinous fibres, less distinctly marked than those of its origin. 
 
 From this difference of direction, it follows that the rectus major and the two obliqui 
 form on each side an equilateral triangle ; in the interval between the two triangles a 
 considerable part of the recti minores is seen. 
 
 Relations. — The recti and obliqui capitis are covered behind by the complexus, from 
 which they are separated by a very strong aponeurotic lamina and much cellular tissue ; 
 
THE POSTERIOR SPINAL MUSCLES. 20T 
 
 they cover tlie posterior arch of the atlas, with the posterior ligaments of the atloido-oc- 
 cipital and atloido-axoid articulations. 
 
 General View of the Posterior Spinal Muscles. 
 
 After the preceding description, it will now be easy to comprehend the general guiding 
 principles in the arrangement of the innumerable, and, at first sight, inextricable fasci- 
 cuh which constitute the fleshy mass known by the general name of the posterior spinal 
 muscles. We shall first recall to mind, that the levers to which all these muscles are 
 ultimately attached are, 1. The row of spinous processes ; 2. The row of articular pro- 
 cesses ; and, 3. The row formed by the transverse processes and the ribs, which, for 
 many reasons, may be regarded as extensions of those processes. 
 
 We shall suppose these three series of levers, and therefore the several points of in- 
 sertion, to be represented by three vertical lines. 
 
 We must remember, also, that the dorsal transverse processes are upon the same line 
 as the lumbar and cervical articular processes, and that the ribs are upon the same line 
 as the lumbar transverse processes and the anterior roots of the cervical transverse pro- 
 cesses. (See Osteology, p. 5.) These data being admitted, we can now reduce all 
 the posterior spinal muscles into the four following orders of fasciculi, two being vertical 
 and two oblique. 
 
 1. The internal vertical or spinous muscles, comprising the spinalis dorsi (i. e., the in- 
 ternal and superficial portion of the longissimus dorsi), the inter-spinalis of the neck, and 
 the recti postici of the head. 2. The external vertical lateral, or transverse muscles, con- 
 nected with the transverse or costiform processes. They comprise the sacro-lumbalis 
 and the inter-transversales, among which the quadratus lumborum may be included. 3. 
 The spino-transverse and spino-articular* oblique muscles, including the longissimus dorsi, 
 with its accessories, the transversalis colli and trachelo-mastoid, the splenius and th6 
 obliquus major. 4. The transverso-spinous and articulo- spinous* oblique muscles, viz., 
 the transverso-spinalis, the complexus, and the obliquus capitis minor. 
 
 Action of the Posterior Spinal Muscles. 
 Having once established the general principles according to which the posterior spinal 
 muscles are arranged, it is very easy to determine the mode of action of each, and to re- 
 duce to very simple elements a mechanism to all appearance so complicated. 
 
 1. The long and short spinous fasciculi being vertical, directly extend the vertebrcil 
 column ; such is the action of the spinalis dorsi and inter-spinalis colli ; the recti capitis, 
 at the same time that they extend the head, rotate it also to the side on which the mus- 
 cles are acting. When the recti muscles of both sides act simultaneously, the head is 
 drawn directly backward. 
 
 2. The fasciculi of the sacro-lumbalis being vertical and lateral, erect the vertebral 
 column, and incline it to one side, when only one set of muscles acts ; when both sets 
 act together, they extend it directly backward. 
 
 3. As the fasciculi of the longissimus dorsi, belonging to the spino-transverse and spi- 
 no-articular group, have their fulcra upon the spine, and are inserted into the articular 
 and the transverse processes or ribs, they conspire in erecting the vertebral column, and 
 keeping it in that position. But, from their obUquity, they produce a slight movement of 
 rotation, those fibres which are attached to the articular processes having less effect than 
 those connected with the transverse processes. In this movement, the front of the body 
 is turned to the side on which the muscles are situated. When the muscles of both 
 sides act together, the spine is extended directly backward. The splenius, which is the 
 representative of the longissimus dorsi for the neck and head, acts in the same way, but 
 with greater effect. Thus, by the contraction of the left splenius, the face is turned to 
 the left side, and the head is drawn backward and to the right side. The obliquus infe- 
 rior jilso acts in the sEune direction. When the two splenii and the two inferior oblique 
 act together, the head is inclined directly backward. 
 
 4. The fixed insertions of the transverso-spinalis being at the articular or transverse 
 processes, and their movable points at the spinous processes, besides the common effect 
 of erecting the vertebral column, they are also able to rotate it, so that the anterior re- 
 gion of the trunk is turned to the opposite side. From its obliquity, this muscle is the 
 principal rotator of the vertebral column. The complexus, which is its representative 
 in the neck, acts upon the head in the same manner, but in a more remarkable degree. 
 Thus, by the contraction of the complexus of the left side, the face is turned to the right 
 side, and the head is inclined backward upon the left side, so that, in rotation, it acts in 
 a precisely opposite direction to the splenius. When all these muscles act together, the 
 trunk is simply drawn erect. The superior oblique assists the complexus in the move- 
 ments of the head. 
 
 Lastly, we may now understand the successive actions which take place along the 
 
 * [The terms spino-transverse and spino-articular are applied to fasciculi passing upward from the spinous 
 to the transverse and articular processes ; transverso-spinous and articulo-spiuous, to such as proceed upward 
 from the transverse and articular to the spinous processes.] 
 
208 
 
 MYOLOGY. 
 
 whole extent of the posterior spinal muscles. The sacrum and the iliac bones furnish a 
 fulcrum for the fasciculi which move the lumbar region : this latter being fixed, then be- 
 comes the fulcrum for those that move the dorsal region, and so on to the head, which 
 alone has independent muscles. It is impossible to extend backward the dorsal region, 
 and the lower part of the cervical, without at the same time erecting the lumbar region; 
 but the head may be moved at will, independently of the vertebral column. 
 
 The posterior spinal muscles maintain in equilibrium the weight of the whole trunk ; 
 hence the lassitude experienced in the back, but especially in the loins, by long-contin- 
 ued standing, walking, or even sitting without a support to the back ; and hence the re- 
 lief afforded by the recumbent posture. 
 
 Rotation, we have seen, scarcely exists in the loins, the back, or the lower part of the 
 neck ; but at the upper part of the neck it is very extensive, and here the rotator mus- 
 cles are proportionally strong, and directed very obliquely. 
 
 MUSCLES OF THE ANTERIOR ABDOMINAL REGION. 
 
 The Obliquus Externus Abdominis. — Obliquus Internus and Cremaster. — Transversalis Ab- 
 dominis . — Rectus Abdominis. — Pyramidalis . 
 
 The muscles of the anterior abdominal region are, the external oblique, the internal 
 oblique, the transversalis, the rectus, and, occasionally, the pyramidalis ; being ten in the 
 whole, five on each side. 
 
 The Obliquus Externus Abdominis. 
 
 Dissection. — 1. Make an incision through the skin of the abdomen extending from the 
 cartilage of the eighth rib obliquely downward and inward, dividing, at the same time, 
 the very firm layer of cellular tissue which immediately covers the muscle. 2. During 
 the preparation of this, as well as 2ill the other abdominal muscles, place a block under 
 the loins, and in the dissection follow exactly the direction of the muscular fibres. 
 The great or external oblique muscle of the abdomen {o,fig. 106, and a, fig. 109), so call- 
 ed from the direction of its fibres (ob- 
 liquus descendens), forms the most su- 
 perficial muscular layer of the abdom- 
 inal parietes, on the sides and front of 
 which it is situated : it is very broad, 
 quadrilateral, and curved upon itself. 
 
 Attachments. — It arises from the ex- 
 ternal surfaces and lower borders of 
 the seven or eight inferior ribs, and is 
 inserted into the anterior half of the ex- 
 ternal lip of the crest of the ilium, into 
 the external edge of the anterior ab- 
 dominal aponeurosis, and by it into the 
 linea alba. The upper or costal attach- 
 ments consist of seven or eight angu- 
 lar tongues, or digitations, fleshy and 
 tendinous in their structure, and arran- 
 ged in an oblique line, running down- 
 ward and backward. 
 
 These digitations increase in size 
 from above downward, as far as the 
 eighth rib, and then diminish to the 
 twelfth. The four or five superior di- 
 gitations are interposed, like the fingers 
 of the two hands (whence the name), 
 between similar prolongations of the 
 serratus magnus. The three or foui 
 lower digitations between those of the 
 latissimus dorsi, by which they are 
 covered. This series of costal attach- 
 ments constituting the upper edge of 
 the muscle, represents a serrated curv- 
 ed line, the convexity of which is di- 
 rected upward and backward. 
 
 The first digitation is attached close 
 to the cartilage of the corresponding 
 rib, the succeeding ones are farther 
 and farther removed from the first, and the last is inserted into the apex of the cartilage 
 of the last rib. 
 
THE OBLiaUUS INTEENUS. 
 
 20d 
 
 From these attachments the fleshy fibres proceed in different directions : the poste- 
 rior pass nearly vertically downward, the middle obliquely downward and inward, and 
 the upper almost horizontally inward ; the posterior terminate by short tendinous fibres 
 at the crest of the ilium ; the anterior at the external concave edge of a broad aponeu- 
 rosis, which forms the superficial layer of the anterior abdominal aponeurosis, and, by 
 interlacing with the corresponding structure of the opposite side, concurs in forming the 
 linea alba, and is folded upon itself below, to form the crural arch, or Poupart's ligament. 
 (See Aponeurolggy.) 
 
 It should be remarked, that the fibres of the external oblique follow exactly the me 
 direction as those of the external intercostal muscles. 
 
 Relations. — The external oblique is covered by the skin, a considerable quantity o* 
 adipose tissue, and behind by a small portion of the latissimus dorsi. It covers the in- 
 ternal oblique, the anterior extremities, and the cartilages of the seven or eight inferior 
 rib's, together with the corresponding external intercostal muscles. The most remark- 
 able relation is that of its posterior border with the outer edge of the latissimus dorsi. 
 Most commonly this border is covered by the latissimus dorsi ; but sometimes a trian- 
 gular space exists between them, which has been much noticed since Petit described a 
 hernial protrusion in it, which he called lumbar hernia. 
 
 Action. — The external oblique performs a threefold action: 1. It compresses the ab- 
 dominal viscera during any exertion, or in expulsion of the faeces, in labour, &c. ; 2. It 
 depresses the ribs, and thus indirectly flexes the vertebral column ; 3. From its obliquity, 
 it rotates the vertebral column, through the medium of the ribs, so that the fore part of 
 the trunk is turned to the opposite side. When the two muscles act together, the tho- 
 rax is inclined directly forward. Hitherto we have supposed that the movable point of 
 the muscle is at the ribs ; if, on the contrary, the thorax be fixed, it then draws the pel- 
 vis upward, and rotates the vertebral column, so that the fore part of the pelvis is turn- 
 ed to the same side as the contracting muscle. 
 
 The Obliquus Internus, and the Cremaster. 
 
 Dissection. — Divide the external oblique across the direction of its fibres, i. e., down- 
 ward and backward. 
 
 The small or internal oblique of the abdomen (obliquus ascendens, p,Jig: 106, and a, Jig. 
 110) is a broad, irregularly-quadrilateral mus- Fig.llO. 
 
 cle, much broader in front than behind, and 
 smaller and thinner than the preceding. It 
 occupies the anterior, lateral, and posterior 
 parts of the abdomen. 
 
 Attachments. — It arises from the spinous 
 processes of the lumbar vertebrae, from the 
 anterior three fourths of the interval between 
 the borders of the iliac crest, and from the 
 crural arch (Poupart's ligaments). It is in- 
 serted into the lower edges of the cartilages 
 of the ninth, tenth, eleventh, and twelfth ribs, 
 and into the linea alba by means of the mid- 
 dle layer of the anterior abdominal aponeu- 
 rosis. The spinal fibres take their origin 
 through the medium of the posterior abdomi- 
 nal aponeurosis : they are few in nmnber. 
 The iliac portion of them arise by very short 
 tendinous fibres, and those which proceed 
 from the crural arch arise from the sort of 
 groove situated on its upper surface. From 
 this threefold origin the fibres proceed in dif- 
 ferent directions : the posterior almost verti- 
 cally upward ; those which arise from the 
 crest of the ilium obliquely upward and in- 
 ward, becoming longer and more oblique an- 
 teriorly ; those which proceed from near the 
 anterior superior spinous process of the ilium 
 are horizontal ; and, lastly, those which arise 
 from the crural arch pass obliquely downward 
 and inward. The posterior fibres terminate 
 at the lower edge of the cartilages of the four 
 inferior ribs, and are continuous with the in- 
 ternal intercostal muscles, in the intervals 
 between the tenth and eleventh and eleventh and twelfth ribs, indicating the analogy 
 between these muscles. I have often observed the insertion into the last rib to be 
 wanting. The middle fibres, which are the most numerous, terminate at the external 
 
 Dd 
 
210 MYOLOGY. 
 
 edge of the middle layer of the anterior abdominal aponeurosis. The fibres arising from 
 the crural arch are few in number, pale, and fasciculated ; some terminate at the pubes, 
 passing behind the inguinal or external abdominal ring ; others proceeding from the 
 ring, in the male, form the cremaster muscle. 
 
 Relations. — It is covered by the external oblique, and behind by a small portion of the 
 latissimus dorsi ; and it lies superficially to the transversalis. The most important re- 
 lations are those of its inferior edge with the inguinal ring of the external oblique, which 
 it partly closes on the inner side, as Scarpa and Bichat have well pointed out, and with 
 the spermatic cord, which passes beneath it, and, during the descent of the testicle, 
 draws with it some of the lower fibres of the muscles ; and hence the looped arrange- 
 ment they assume. 
 
 The cremaster. The loops so well described by M. Jules Cloquet are very variable, 
 and do not always appear to me to constitute the entire muscle. According to this 
 anatomist, the cremaster is nothing more than the lower fibres of the internal oblique, 
 that had been entangled with the testicle during its descent, forming loops in front of the 
 cord, the concavity of which is directed upward, and which may be traced to the bottom 
 of the scrotum. But I have often been convinced, from the examination of subjects in 
 which the cremaster was much developed, that this muscle {b, Jigs. 109, 137) consists 
 principally of a longitudinal fasciculus, partly derived, it is true, from the lower fibres of 
 the internal oblique, but consisting partly, also, of proper fibres arising from the crural 
 arch, near the external pillar of the ring ; and that this fasciculus is lost upon the proper 
 sheath of the cord, to which it is intimately united. The oflSce of this muscle is to 
 raise the entire testicle. The slow vermicular motion observed in the scrotum during 
 the venereal orgasm, or from the action of cold, is not at all connected with it. 
 
 The actions of the internal oblique are, 1. Compression of the abdominal viscera; 2. 
 Depression of the ribs, and, consequently, flexion of the trunk ; 3. Rotation of the trunk, 
 so that the fore part of the body is turned to the same side. The right internal oblique, 
 therefore, co-operates with the left external oblique ; when it acts with its fellow, the 
 thorax is drawn directly towards the pelvis ; but if the chest is fijced, they move the pel- 
 vis upon the loins. 
 
 The Transversalis Abdominis. 
 
 Dissection. — 1. Make a horizontal section of the internal oblique ; 2. Dissect with care 
 the two flaps of this nmscle, following the direction of the fibres of the transversalis ; 3. 
 In order to obtain a good view of the costal attachments, open the abdomen and exam- 
 ine them on the inner surface of the ribs ; this may be omitted until the diaphragm is to 
 be inspected. 
 
 The transversalis abdominis, so named from the direction of its fibres, is situated more 
 deeply than the two preceding muscles, and, like them, is irregularly quadrilateral (b, fig. 
 110). 
 
 Attachments. — It arises from the six lower ribs, from the anterior three fourths of the 
 internal lip of the crest of the ilium, and from the spinous and transverse processes of 
 the lumbar vertebrae. It is inserted into the linea alba by means of the deep layer of 
 the anterior abdominal aponeurosis. The costal attachments consist of fleshy digita- 
 tions interposed between those of the diaphragm, the two muscles being actually contin- 
 uous at the two inferior intercostal spaces ; the vertebral attachments are efiected by 
 means of the posterior abdominal aponeurosis ; and from the ilium it arises by very 
 short tendinous fibres internally to the small obliqije. From these three origins the fleshy 
 fibres proceed parallel to each other and horizontally inward ; the lower ones alone are 
 slightly inclined downward and inward ; the middle fibres are the longest. They are all 
 inserted into the external convex edge of a tendinous expansion, which constitutes the 
 posterior layer of the anterior abdominal aponeurosis. 
 
 Relations. — The transversalis is covered by the internal oblique, and rests upon the 
 peritoneum, from which it is separated by a fibrous lamina, which is very distinct in 
 front, where it is named the fascia transversalis. 
 
 Actions. — 1. It acts more powerfully upon the abdominal viscera than any of the pre- 
 ceding muscles, compressing them strongly, like a girth, against the vertebral column, 
 and assisting greatly in the process of defecation. 2. It draws inward the rib to which 
 it is attached, and thus materially assists in expiration. 
 
 The Rectus Abdominis. 
 
 Dissection. — 1. The subject being laid upon its back, place a block under the loins ; 2. 
 
 After having removed the skin, make a vertical incision through the strong aponeurosis, 
 
 at about two fingers' breadth from the linea alba ; 3. Dissect off the two flaps inward and 
 
 : outward. The adhesions between this aponeurosis and the muscle are, however, so in- 
 
 'timate at many points, that it is impossible to separate them. 
 
 The rectus abdominis (c, fig. 110) is situated at the anterior and middle part of the ab- 
 domen on each side of the linea alba, and occupies the sp.^ce between the pubes and the 
 . cartilage of the fifth rib. It is flattened like a riband in front and behind ; it is about 
 
THE RECTUS ABDOMINIS. 
 
 three or four fingers' breadth wide above, and only two below. Its breadth is generally 
 in an inverse proportion to its thickness. 
 
 Attdchmcnts. — It arises from the upper edge of the os pubis, in the space between the 
 spine and the symphysis ; and is inserted in front of and below the cartilage of the sev- 
 enth rib and costo-xiphoid ligament, to the cartilages of the fifth and sixth ribs, and 
 sometimes to the bone also. 
 
 The pubic attachment is a flat tendon, consisting of two very distinct portions, of 
 which the external is the larger. This tendon is continuous by its external border Avith 
 the fascia transversalis. It is separated from its fellow of the opposite side by a very 
 narrow and thick fibrous septum, which forms the lower part of the linea alba. Some- 
 times the internal tendinous fibres intersect with those of the opposite side in front of 
 the symphysis pubes ; and some fleshy fibres often arise from the sides of the linea alba. 
 The presence or absence of the pyramidalis affects the size of the lower part of this 
 muscle. From this tendinous origin the fleshy fibres proceed vertically upward (whence 
 the name oi rectus). At the upper part, where they are prolonged in an expanded form 
 upon the thorax, they are slightly oblique from within outv^ard, and divided into three 
 unequal portions : the internal, the smallest, is attached to the cartilage of the seventh 
 rib and to the costo-xiphoid ligament ; the middle, which is larger, is fixed to the carti- 
 lage of the sixth rib ; and the external, by far the largest, to the cartilage of the fifth rib. 
 Very often a small portion of the muscle is insertad into the base and edges of the xi- 
 phoid cartilage, thus justifying the name of stemo-puhien given to it by Chaussier. It is 
 not uncommon to find this muscle give off a fourth bundle to the fourth rib, and even an 
 aponeurotic expansion to the sterno-cleido-mastoid. The rectus is interrupted by two, 
 three, four, or five tendinous intersections, which pass transversely or obUquely across the 
 muscle in a flexuous or zigzag course, seldom occupying either the entire thickness or 
 width of the muscle, which they divide into so many smaller muscles. There are always 
 more intersections above than below the umbilicus. 
 
 Relations. — This muscle is contained in a very strong tendinous sheath, which is form- 
 ed by the anterior abdominal aponeurosis, is thicker in front than behind, much stronger 
 below than above, and completely isolates the muscle. Below and behind, this sheath 
 is deficient, in which situation the muscle (passing through the openings. Jig. 1 10, in the 
 aponeurosis of the transversalis) rests directly upon the peritoneum ; the upper and pos- 
 terior part of the sheath is also wanting, so that the muscle is in immediate contact 
 with the cartilages of the fifth, sixth, seventh, eighth, and ninth ribs, and with the cor- 
 responding intercostal muscles. The linea alba occupies the interval between the two 
 muscles, which is much larger above than below the umbilicus ; but the most important 
 of all the relations of the rectus is that of its posterior surface with the epigastric artery, 
 which we shall hereafter notice. 
 
 Actions. — This muscle, having its fixed point below, and its movable attachments di- 
 vided between the fifth, sixth, and seventh ribs, depresses the whole thorax, and, con- 
 sequently, the vertebral column. Few muscles are so favourably situated as the rectus, 
 which both acts upon a very long lever, and is inserted at right angles to the part to be 
 moved. 
 
 As the rectus forms a curve, the convexity of which is directed forward, and cannot 
 contract without becoming rectilinear, it follows that the first effect of its contraction is 
 the compression of the abdominal viscera; hence it assists in expelling the contents of 
 the bladder, rectum, and uterus ; it aids in expiration, by depressing the ribs, and, by 
 keeping them fixed when the thorax is dilated, it assists in the performance of any ef- 
 fort. \\Tien the fixed point is above, the rectus becomes a flexor of the pelvis. 
 
 What are the uses of the intersections 1 It is generally stated that their effect is to 
 increase the number of fibres, and thereby augment the force of the muscle ; and in sup- 
 port of this a principle is adduced, which is incontestable in itself, viz., that the power 
 of a muscle is in a direct ratio to the number of its fibres ; for if each fibre represent one 
 partial power, the more of these the greater must be the total power. But it has been 
 overlooked, that this law only applies to fibres arranged side by side, not to those which 
 are placed end to end. In fact, it may be experimentally shown that, when two equal 
 forces are applied to a lever, parallel to each other, they produce double the effect either 
 would have done separately ; but if one be made continuous with the other, and both are 
 then applied to the same lever, they only produce an effect equal to that of either per se. 
 These intersections, therefore, do not increase the power of the muscle ; nor do they 
 diminish the extent of motion, for the sum of the contractions of the small muscles into 
 which they divide the recti is equal to that of an undivided muscle. What, then, are 
 the uses of these intersections 1 Can it be intended, as Bertin has said, to associate 
 the obUque muscles with the recti by means of the intimate adhesions existing between 
 .them and the aponeuroses 1* 
 
 * Benin considers these adhesions as true points of attachment tor the muscles of the aiitlomeii, so that 
 when the rectus contracts, it acts :iot only upon tho pubes, but also upon the crests of tlie ilia, through the 
 medium of the abdominal aponeuroses. Professor Berard, who Irmgs forward this forgotten opinion of Ber- 
 tin iRipert. Gentr. dcs Sc. Med., art. Abdomen), correctly observes, that tho obliquus internus only adheres 
 to tho rectus. In the same aficle M. Biirard declares he is not satisfied that the intersections increMe the 
 , I \ver of the recti muscles. 
 
SICI^ 
 
 MYOLOGY. 
 
 ;, v'-.r; wV^jtU-TSia The Pyramidalis. •:^^^^>^.^At.::< 
 
 The pyramidalis {d, fig. 1 10), a small triangular muscle which is often deficient, occu- 
 pies the lower part of the abdomen on each side of the linea alba. It arises from the 
 pubis and the anterior ligament of the symphysis by tendinous fibres, from which the 
 fleshy portion proceeds upward, the internal fibres vertically, the external obliquely up- 
 ward and inward, and terminates by a pointed extremity, which is attached to the hnea 
 alba, and forms the apex of the muscle, the base being at the os pubis. It is covered 
 by the aponeuroses of the obliqui and transversalis muscles, and rests upon the rectus. 
 The lower part of the rectus and the pyramidalis are united together. When the latter 
 is wanting, the lower end of the rectus is proportionally increased in size, and vice versa- 
 There are sometimes two pyramidales on one side, and one on the other ; sometimes the 
 two are of unequal size. In a negro I found them extending beyond the middle of the 
 space between the pubis and the umbilicus. 
 Action. — It is a tensor of the linea alba. 
 
 DIAPHRAGMATIC REGION. 
 
 T^e Diaphragm. 
 
 Dissection. — Description. — Attachments. — Relations. — Action. 
 Dissection. — In order to expose this muscle, it is necessary to open the abdomen and 
 remove all the abdominal viscera, taking great care in detaching the liver, stomach, and 
 Kidneys. Tie the oesophagus and vena cava where they pass through the diaphragm, 
 and cut them below the ligature. Raise the peritoneum with the fingers or forceps, and 
 tear it gently away ; thus exposing the lower surface of the muscle without using the 
 scalpel. All the insertions of the diaphragm are well seen on this surface. In order to 
 study the convex surface of the muscle, another subject should be provided, and the tho- 
 rax opened before the abdomen. This is the only method by which a good idea of it can 
 be obtained ; for when the abdomen has been previously opened, the muscle becomes 
 relaxed as soon as the thorax is cut into, and affords no idea of its naturally vaulted form. 
 The diaphragm (septum transversum, a a, fig. Ill), which exists in mammalia only 
 p^ jlj is, according to the expression of Haller, with the 
 
 exception of the heart, the most important muscle. 
 I in '\ f f \U\ of the body. It is a muscular septum, sitotticd ob- 
 
 liquely at the junction of the upper with the two 
 lower thirds of the trunk. It separates the thorax 
 -a from the abdomen, constituting the floor of the for- 
 mer and the roof of the latter. All other muscles 
 ,^ are placed on the outside of, or around, the levers 
 which they are intended to move ; but the diaphragm 
 alone is situated within those levers, like the mus- 
 cles of animals having an external skeleton. 
 
 The diaphragm divides the body into two unequal 
 parts : an upper, or supra-diaphragjnatic ; and a lower, 
 or infra-diaphragmatic. It is placed on the median 
 line, but is not symmetrical. It is elliptical in form, 
 its longest diameter being from side to side, thin and 
 flattened, and resembles an arch, or, rather, a fan, 
 the broad and circular portion of which is horizon- 
 tal, while the narrow part is vertical, and at right 
 angles to the former. The older anatomists, there- 
 fore, divided it into two portions : the upper, or great 
 muscle of the diaphragm ; and the lower, or small m)is 
 cle of the diaphragm. 
 
 Attachments. — It arises partly from the lumbar re 
 gion of the vertebra, column, in front of the bodies and intervertebral substances of the 
 second, third, and fourth lumbar vertebra? ; partly from the posterior surface of the ster- 
 num and the base of the ensiform cartilage ; and partly from the posterior surface and 
 upper edge of the cartilages and contiguous bony portions of the seventh, eighth, ninth, 
 tenth, eleventh, and twelfth ribs. Sometimes it is attached also to the sixth rib. 
 
 The vertebral origin consists of two tendons, formed by several smaller vertical ten- 
 dons, situated in front of each other, which are blended with the anterior common liga- 
 ment of the spine. To these tendons two thick, fleshy bundles succeed, which pass ver- 
 tically upward, become gradually thicker and broader, give off" a fasciculus to each other, • 
 and are inserted into the posterior notch in the aponeurosis, having the form of a trefoil 
 leaf, which forms the centre of the muscle, and is therefore called the central aponeurosis 
 of the diaphragm {b, fig. 1 1 1), or cordiform tendon. These two fleshy bundles and their ten- 
 dons (c c) are named the pillars, crura, or appendices of the diaphragm. The right crus 
 
THE DIAPHRAGM. 213 
 
 IS anterior, larger, and descends lower down than the left. Each pillar is occasionally 
 divided into two very distinct secondary pillars, and the trace of this division is always 
 visible in the opening which gives passage to the great splanchnic nerve. The two pil- 
 lars of the diaphragm leave between them an interval, divided into two portions or rings 
 by the fleshy fasciculi which they mutually give to each other. The communicating fas- 
 ciculus from the right pillar is anterior, and larger than that from the left. Of the two 
 openings (ir rings between the pillars of the diaphragm, the loxcer or aortic {d) is parabolic, 
 and gives passage to the aorta, the vena azygos, the thoracic duct, and sometimes, also. 
 to the left great sympathetic nerve. Like all orifices through which arteries pass, it is 
 aponeurotic in its structure, being formed by the tendons of the pillars of the diaphragm 
 at the sides, and above by a fibrous prolongation of those tendons, which arches over 
 and completes the ring : the upper or (Esophageal opening (e) gives passage to the oesoph- 
 agus and the pneumo-gastric nerves; it is elliptical, and altogether muscular. In one 
 subject, however, I found the upper part tendinous ; and in another, a small muscular 
 fasciculus proceeded from the edge of the orifice, and was lost upon the coats of the 
 oesophagus. Haller has twice observed the same peculiarity. 
 
 A fibrous prolongation proceeds outward from the tendon of each crus, and is fixed to 
 the base of the corresponding transverse process of the first lumbar vertebra, so as to 
 form an arch on each side (fig. Ill), under which the upper end of the psoas muscle pass- 
 es (ligamentum arcuatum proprium). Another aponeurotic arch, which has been improp- 
 erly called ligamentum arcuatum {ligament cintre du diaphragme), for it is nothing more 
 than the upper edge of the anterior layer of the aponeurosis of the transversalis muscle 
 folded upon itself, extends from the outer extremity of the preceding arch to the lower 
 border and apex of the last rib ; under it passes the superior portion of the quadratus 
 lumborum muscle {fig. 111). From both these arches muscular fibres pass forward, and 
 are inserted into the corresponding part of the cordiform tendon. Indeed, the five ten- 
 dinous arches which we have just described, viz., the aortic in the middle, and the two 
 on each side for the psoas and quadratus lumborum muscles, give origin to all the fleshy 
 fibres which terminate at the posterior notch of the central tendon of the diaphragm 
 The existence of these arches led Haller and Scemmering to reckon three or four crura 
 on each side. The cordiform tendon in which the preceding muscular fibres are insert- 
 ed serves, in its turn, as the origin of other fibres, which constitute the vault of the dia 
 phragm. This central aponeurosis (i), to which so much importance was attached by 
 the ancients, under the name of the phrenic centre, and which some modern anatomists 
 regard as the central point of the entire aponeurotic system of the human body, occupies 
 the middle of the vault of the diaphragm, immediately below the pericardium, with which 
 its circiunference is blended in adults, but from which it may be easily separated in young 
 subjects : it is a sort of aponeurotic island, surrounded on all sides by muscular fibres, 
 and converting the diaphragm into a true digastric muscle. In form, it resembles a tre- 
 foil leaf, with a notch in the situation of the pedicle ; each division is called a wing or 
 leaflet ; the middle leaflet is the largest, the right the next, and the left the smallest. Be- 
 tween the right and the middle le^et is an opening (/), sometimes converted into a ca- 
 nal for the inferior vena cava. This orifice is entirely tendinous, and of a quadrangular 
 shape when the vena cava is removed. It is bounded by four tendinous fasciculi, which 
 meet at right angles. The cordiform tendon is itself composed of several planes of fibres ; 
 the principal of which consists of a diverging series, running forward, and uniting into ir- 
 regular, straight, or curved bundles, which intersect each other at various angles ; an 
 arrangement that gives great strength to the tendon. The fleshy fibres are attached to 
 all points of the circumference of this tendon, and radiate from it in all directions. The 
 anterior, very short, and sometimes aponeurotic, proceed to the base of the ensiform car- 
 tilage, describing a slight curve, with the concavity directed downward. A triangular 
 interval, or else several small spaces, are often left between these fibres, establishing a 
 communication between the cellular tissue of the thorax and that of the abdomen. 
 Hence, diaphragmatic hernias occasionally occur ; and pus, formed in the neck or medi- 
 astinum, may ultimately point at the epigastrium. It is not uncommon to find the ster- 
 nal attachment of the diaphragm partially or entirely deficient. ^ 
 The lateral muscular fibres, which are much longer than the anterior, describe very 
 well-marked curves, and form an arch, with the concavity downward, but more convex 
 and projecting on the right than the left side. They then divide into six or seven digi- 
 tations on each side, which are attached to the ribs, intersecting with the costal inser- 
 tions of the transversalis abdominis. It is not uncommon to find considerable intervals 
 between the digitations of this muscle, opposite which the pleura and peritoneum are in 
 contact ; this more especially occurs between the eleventh and twelfth ribs. The fas- 
 ciculus for the twelfth rib is sometimes deficient, its place being occupied by a tendon. 
 The direction of the fibres of the diaphragm is then radiated and curvilinear in the hori- 
 zontal portion, but radiated and rectilinear in the vertical portion. 
 
 Relations. — 1. The inferior or abdominal surface, concave in the middle, and much more 
 concave on the right side, where it corresponds to the convex upper surface of the liver, 
 than on the left, where it is in contact with the spleen and the large extremity of the 
 
214 MYOLOGY. 
 
 Stomach, is covered by the peritoneum throughout the greater part of its exteiit, except- 
 ing at the situation of the coronary ligament of the liver, and also behind, where it is in 
 relation with the third portion of the duodenum, the pancreas, the kidneys, the supra- 
 renal capsules, and the solar plexus. 
 
 2. Thoracic, or upper surface. The middle portion is convex, and covered by the pleu- 
 ra and pericardium ; it is flat, and serves as a floor to support the heart, the inferior sur- 
 face of which rests upon it ; hence the pulsations of the heart felt in the epigastrium. 
 The lateral portions are convex, and contiguous to the lungs. The convexity is greater 
 on the right than on the left side : the highest point to which the right side reaches, in 
 the natural condition, is the level of the fourth rib ; the highest point which the left side 
 attains is opposite the fifth rib. Hence the surgical rule of operating for empyema high- 
 er on the right than on the left side.* 
 
 The height to which the diaphragm is raised varies remarkably ; it reaches very much 
 higher in the foetus than in the adult. Should the muscle be only slightly vaulted, it is 
 considered by medical jurists as one of the presumptive proofs that the infant has respired. 
 
 3. Circumference. — ^With the exception of the crura, the diaphragm is connected by its 
 circumference only with one muscle, viz., the transversalis, which presents exactly cor- 
 responding attachments, so that, indeed, these two muscles may be considered as form- 
 ing one contractile sac, interrupted by the costal insertions. 
 
 Action. — The diaphragm forms an active septum between the thorax and abdomen, 
 which affects the viscera of both cavities. The two pillars act like the long muscles ; 
 the body of the diaphragm after the manner of the hollow muscles. When the pillars 
 contract, they take their fixed point upon the lumbar vertebrae, and their movable point 
 upon the notch at the back of the cordiforra tendon, which is carried backward and down- 
 ward. This aponeurosis, in its turn, becomes a fixed point for all the other curved ra- 
 diated fibres that are attached to the ribs. The first effect of the contraction of a curved 
 fibre is its becoming straight ; and, in this process, the highest part of the curve is drawn 
 down towards a level with its extremities : the vertical diameter of the thorax is, there- 
 fore, increased, and that of the abdomen proportionally diminished ; but, during contrac- 
 tion, the fibres act equally upon both their points of insertion, and, as the cordiform ten- 
 don is fixed, and the costal attachments are movable, the ribs are drawn inward, and the 
 transverse diameter of the thoracico-abdominal cavity thereby diminished. The antero- 
 posterior diameter would be equally diminished, were it not for the inclination of the di- 
 aphragm downward and backward, in consequence of which the abdominal viscera are 
 pressed downward and forward. Some experimentalists, among whom we may men- 
 tion Haller and Fontana, have asserted that the diaphragm may become convex below 
 during a forced contraction, but I beheve this can only take place when air has been ad- 
 mitted into the cavity of the pleura. 
 
 We shall now consider the effects of the contraction of the diaphragm upon the open- 
 ings by which it is perforated. 
 
 The elliptical, or, rather, oval opening for the oesophagus, being entirely muscular, is 
 contracted during the action of the diaphragm, in the same manner as the mouth by that 
 of the orbicularis muscle : hence the oesophagus is compressed. From this it has been 
 concluded that vomiting cannot take place during inspiration, but experience proves the 
 contrary, vomiting being favoured by this compression. 
 
 It is generally said that the orifice for the vena cava is not affected by the contraction 
 of the diaphragm ; but if we draw upon the muscular fibres in the neighbourhood of this 
 opening, we see at once that it is diminished in size ; HaUer has even witnessed this in 
 a living animal during inspiration. The arch, or, rather, the parabolic canal, which gives 
 passage to the aorta, is also contracted, and the vessel slightly compressed ; hence, 
 doubtless, arises the frequency of aneurisms of tliis artery, where it passes through the 
 pillars of the diaphragm. 
 
 LUMBAR REGION. 
 The Psoas and Illiacus. — Psoas Parvus. —Quadratus iMmborum. 
 The lumbar region includes the psoas and iliacus, the psoas parvus (when it exists), 
 and the quadratus lumborum. 
 
 7'he Psoas and Iliacus. 
 
 I consider that, since the psoas and iliacus muscles have a common insertion, they 
 should be described as a single muscle, having a double origin, which we shall term the 
 psoas-iliac muscle. 
 
 Dissection. — Having opened the abdomen, tear away with the fingers the peritoneum 
 covering the iliac fossae and the lumbar regions. Remove, at the same time, the intes- 
 
 * This rule should be disregarded : the object of it is to open the thorax at the lowest part, so as to give a 
 more easy exit to the liquid ; but the lowest portion would be behind, in the deep groove formed by the dia- 
 phragm with the parietes of the thorax. It is of little importance to find the most depending part ; it is suf- 
 ficient to establish an outlet ; the fluid will always flow to it. 
 
THE PSOAS ANDi,ILIACUS. 215 
 
 tines, the stomach, the pancreas, the kidney, the liver, and the spleen ; detach the iliac 
 fascia. In order to see the femoral insertion of this muscle, divide the crural arch 
 through the middle. Dissect with care the muscles at the anterior and superior part of 
 the thigh, especially the pectineus, with which this muscle is in immediate relation 
 Remove the adipose cellular tissue which surrounds the crural vessels and nerves. 
 
 The psoas-iliac muscle is deep-seated, and extends from the sides of the vertebral 
 column and front of the iliac fossa to the lesser trochanter of the femur. It arises above 
 by two very distinct muscular masses ; an internal, long, or lumbar portion '[lumbaris, 
 sive psoas, Riolanus), the great psoas of authors ; and an external, broad, or iliac portion, 
 constituting the iliacus (iliacus intemus, Albinus). 
 
 1, The lumbar portion (psoas magnus, from tpdai, the loins, g g, Jig. Ill) arises from 
 the sides of the bodies of the five lumbar and last dorsal vertebrae, and of the correspond- 
 ing inter- vertebral substances, and from the base of the transverse processes, by means 
 of aponeurotic fibres, united by tendinous arches, which correspond to the grooves on 
 the bodies of the lumbar vertebrae, so that the muscle is, in reality, only attached to the 
 upper and lower borders of the bodies of the vertebra, and to the inter-vertebral sub- 
 stances. From this double origin the fleshy fibres proceed in the form of a conoid bun- 
 dle, compressed on the sides, and directed obliquely downward and outward ; the sum- 
 mit of the cone is flattened, and embraced by the ligamentum arcuatum ; the body is 
 thicker and rounded, and diminishes in size inferiorly, as its constituent fibres are grad- 
 ually attached to a tendon, which, though at first concealed in its centre, afterward ad- 
 vances towards the anterior and external surface, receives the fibres of the iliacus, and 
 is inserted into the lesser trochanter of the femur. The great psoas, therefore, resem- 
 bles a double cone or spindle. 
 
 Its component fibres are not fasciculated, but are united by a very delicate cellular 
 tissue. The complete absence of fibrous tissue explains the weakness of this muscle, 
 which may be torn with the greatest facility, and perhaps, also, the frequency of its dis- 
 eases. Its tenderness in the ox causes it to be a favourite joint for the table, under the 
 name of short ribs (aloyau) : perhaps this delicacy of texture is connected with the pres- 
 ence of a large plexus of nerves in the substance of the muscle. 
 
 2. The iliac portion (iliacus muscle ; iliacus intemus, Alb., i i,fig. Ill) fills the internal 
 Uiac fossa. It arises from the whole of this fossa, from the crest of the ilium, the ilio- 
 lumbar ligament, and the base of the sacnun, and from the anterior superior iliac spine, 
 the notch below, the anterior inferior iliac spine, and even the capsular ligament of the 
 hip-joint. The fleshy fibres converge, and are immediately attached to the external 
 edge of the common tendon, which we have described as originating in the substance of 
 the psoas. This tendon, which receives on its inner side all the fibres of the psoas, and 
 even those fibres of the iliacus which arise from the brim of the pelvis, runs along the 
 side of the brim, diminishing its transverse diameter, and emerges from the pelvis under 
 the crur£d arch, passing through a remarkable groove between the anterior inferior spi- 
 nous process of the ilimn, and the eminentia ilio-pectinea. In this situation all the fibres 
 of the psoas terminate ; those that remain of the iliacus are successively attached to 
 the outside of the tendon, like the barbs of a feather to the shaft, and form a triangular 
 fleshy bundle, which inmiediately changes its direction, passes backward, inward, and 
 downward among the muscles of the thigh, turns slightly round, so that its anterior sur- 
 face looks somewhat inward, and its posterior surface outward, and is inserted into the 
 lesser trochanter, which it embraces on every side, even to its base. It is not uncom- 
 mon to find the fasciculus which comes from the anterior inferior spinous process of the 
 iUum and the capsular ligament forming a very distinct muscle, which has been often 
 described separately, under the name of the ilio-capsulo-trochantericus ; it is inserted 
 separately below the lesser trochanter into the oblique line which extends from this pro- 
 cess to the linea aspera. 
 
 Relations. — 1. The lumbar portion (psoas magnus) is in relation anteriorly with the 
 diaphragm, the kidney, the ascending colon on the right side, the descending colon on 
 the left, the peritoneum, and the psoas parvus, when it exists. The external Uiac artery 
 and vein run along the anterior surface. On the inside it corresponds to the bodies of 
 the lumbar vertebrae and the lumbar vessels ; behind, to the transverse processes of the 
 lumbar vertebrae and the quadratus lumborum. The lumbar plexus is situated posterior- 
 ly in the substance of the psoas magnus ; this explains the violent pain in the loins ex- 
 perienced during repeated contractions of this muscle, and, during pregnancy, from the 
 pressure of the gravid uterus. 2. The iliac portion lines the iliac fossa ; it is covered 
 by the peritoneum, the caecum, and the end of the small intestines on the right side, and 
 by the sigmoid flexure of the colon on the left. These two muscles form a projection on 
 the inside, which reduces the transverse diameter of the brim of the pelvis from five 
 inches to four and a half 3. The psoas and iliacus exactly fill that portion of the crural 
 arch in which they are placed, so that hernias never take place in this situation. 4. In 
 the thigh, the common tendon is separated anteriorly from the cellular tissue of the 
 groin by the deep femoral fascia ; it is in relation with the crural nerve, which passes 
 out of the pelvis in the same sheath as, but below, the psoas, in a groove between the 
 
iJ16 MYOLOGY. 
 
 latter and the iliacus, between which parts it forms the only separation. Behind, it is in 
 contact with the anterior border of the os coxae and the hip-joint, a large bursa inter- 
 vening, which often communicates with the synovial capsule of the joint, by an opening 
 of variable size.* The inner edge of the psoas-iliac muscle is in relation with the outer 
 edge of the pectineus, and with the femoral artery, which it sometimes covers. The 
 external edge is at first in relation with the sartorius, and afterward with the rectus 
 femoris. The psoas-iliac is also covered by the lumbo-iliac fascia {fascia iliaca), which 
 will be described hereafter. (Vide Aponeurology.) 
 
 Actions. — The psoas-iliac muscle flexes the thigh upon the pelvis ; this action is the 
 more energetic from the fact of the fixed points of insertion being both on the vertebral 
 column, and on the iliac fossa. The two portions of the muscle do not act in the same 
 direction ; but when they contract simultaneously, the opposite forces are destroyed, and 
 the traction upon the common tendon becomes direct. This muscle affords a remark- 
 able example of the reflection of a muscle over a pulley, which greatly increases the 
 power, by changing the direction of insertion nearly to the perpendicular. The action 
 of this muscle, therefore, must only be calculated from the point of reflection, i. e., the 
 anterior edge of the ilium. It is in semiflexion that the muscle becomes perpendicular 
 to the femur, and acts with the greatest power ; and, therefore, the Tnomentum of the 
 muscle occurs at that period. The psoas-iliac is at the same time a rotator outward of the 
 femur, on account of the obliquity of its insertion at the inner and back part of that bone. 
 When the femur is fixed, as in standing, it draws the lumbar portion of the spine and the 
 pelvis forward ; and its iliac portion rotates the pelvis so as to turn the front to the opposite 
 side. When the muscles of each side act together, the trunk is inclined directly forward. 
 
 The Psoas Parvus. 
 
 This muscle (Z I, fig. Ill) lies in front of the preceding ; it arises from the twelfth dor- 
 sal vertebra, the first and sometimes the second lumbar vertebrae, and the corresponding 
 inter-vertebral substances. It forms a small, flat bundle, at first appearing to be a de- 
 pendance of the psoas magnus, but soon becoming isolated ; it terminates in a broad, 
 shining tendon, which crosses the psoas magnus at a very acute angle, and is inserted 
 into the upper part of the ilio-pectineal eminence, and the corresponding portion of the 
 brim of the pelvis. This small muscle receives the lumbo-iliac aponeurosis (fascia ili- 
 aca) on its outer edge. It is often absent ; we have sometimes seen it double. Its use 
 is evidently to render the iliac fascia tense, and to tie down and prevent displacement 
 of the lumbar portion of the psoas magnus. It may assist in flexing the pelvis upon the 
 thorax, as in climbing ; in the recumbent and supine position, if one muscle acts alone, 
 it inclines the pelvis to its own side ; but if its fixed point be below, it inclines the trunk 
 to the same side. 
 
 The Quadratus Lumborum. 
 
 Dissection. — Expose the posterior surface, by carefully detaching the common mass Oi 
 the posterior spinal muscles ; and to view the anterior, open the abdomen and remove 
 the viscera. This muscle is enclosed in a sheath formed by the anterior and middle lay- 
 ers of the posterior aponeurosis of the transversalis abdominis ; divide this sheath, and 
 the muscle will be completely laid bare. 
 
 The quadratus lumborum (m m, fig. Ill) is quadrilateral in shape, and broader below 
 than above ; it is situated in the lumbar region, on the sides of the vertebral column, be- 
 tween the crest of the ilium and the last rib. 
 
 Attachments and Direction. — It arises from the ilio-lumbar ligament, and from about 
 two inches of the adjacent part of the iliac crest, by aponeurotic fibres, which, on the 
 outer side especially, are very long. These fibres are bound down by others, crossing 
 them at right angles, and give origin to the fleshy part of the muscles, which proceeds 
 upward and a little inward, in the following manner : 1 . Some of the fibres pass verti 
 cally upward, and are inserted into the last rib, to an extent wliich varies in different in 
 dividuals. 2. Others are directed very obliquely inward, and divide into four fleshy bun- 
 dles, inserted, by means of a similar number of tendons, into the summits of the transverse 
 processes of the four superior lumbar vertebrae. 3. There is most commonly a third 
 plane, anterior to the preceding, and consisting of fibres, which arise from the summits 
 of the transverse processes of the third, fourth, and fifth lumbar vertebrse, and are in- 
 serted into the lower edge of the last rib. 
 
 Connexions. — The quadratus lumborum somewhat resembles the rectus abdominis, in 
 being enclosed and bound down in a very strong tendinous sheath ; it has, therefore, no 
 direct relations. In front are the kidney, the colon, the psoas, and the diaphragm ; be- 
 hind is the common mass of the spinal muscles, beyond which its outer border some- 
 what projects, especially below. Its most important relations are with the kidney and 
 the colon. It is the guide for the necessary incisions in operations performed in this re- 
 gion, particularly in nephrotomy. 
 
 * See note. p. 296. 
 
INTEK-TRANSVERSALES, RECTUS CAPITIS LATERALIS, AND 8CALENI. 217 
 
 Action. — ^With its fixed point at the crest of the ilium, this muscle depresses the last 
 rib, by means of its costal insertions, thus acting as a muscle of expiration ; and it in- 
 clines the spine to its own side, through the medium of its vertebral attachment. With 
 its fixed point above, it inclines the pelvis to its ow^n side. 
 
 LATERAL VERTEBRAL REGION. 
 
 The Inter-traTisversales and Rectus Capitis Lateralis. — Scaleni. 
 
 The lateral muscles of the vertebral column are the inter-transversales of the neck 
 and loins, the rectus capitis lateralis, and the scaleni. The quadratus lumborum, already 
 described, belongs also to this region. 
 
 The Inter-transversales and Rectus Capitis Lateralis. 
 The inter-transversales muscles exist only in the neck and the loins ; in the back 
 they are represented by the intercostals, an additional proof of the analogy between the 
 ribs and the cervical and lumbar transverse processes. Many celebrated anatomists, how- 
 ever, admit the existence of inter-transverse muscles in the back, but they are nothing 
 more than deep-seated fasciculi of the transverso-spinalis. 
 
 1. Inter-transversales of the Neck {a to a, fig. 112). — There are two of these muscles in 
 each inter-transverse space, an interior and a posterior. They are small quadrilateral 
 muscles, one arising from the anterior, the other from the posterior margin of the groove 
 on the transverse process below : from these origins the fibres proceed vertically upward, 
 and are inserted into the transverse process of the vertebra above. 
 They are separated from each other by the anterior branches of 
 the cervical nerves and by the vertebral artery, the canal for 
 which they serve to complete. Behind, they are in relation Avith 
 the posterior spinal muscles, the splenius, the levator anguli 
 scapulas, the transversdis colli, and the cervicalis descendens ; 
 and in part with the rectus capitis anticus major. 
 
 2. Rectus Capitis Lateralis {h,fig. 112). — This muscle may be 
 regarded as the first posterior inter-transversalis of the neck, and 
 the rectus capitis anticus minor, which we shall presently de- 
 scribe as the first anterior inter-transversalis. The comparative 
 size of the rectus lateralis is not opposed to this view, for it is 
 connected with the increased development of the corresponding 
 cranial vertebra. It arises from the transverse process of the 
 atlas, and proceeds directly upward, to be inserted into the jugu- 
 lar surface of the occipital bone, immediately behind the fossa of that name. This mus- 
 cle separates the jugular vein, with which it is in contact in front, from the vertebral 
 artery, to which it is contiguous behind. 
 
 3. Inter-transversalis of the Loins. — The absence of any groove upon the lumbar trans- 
 verse processes would lead us at once to infer that in this region there must be only one 
 muscle in each inter-transverse space. There are, therefore, five on each side. The 
 first extends from the transverse process of the last dorsal to that of the first lumbar ver- 
 tebra ; and the last from the transverse process of the fourth to that of the fifth lumbar 
 vertebra. 
 
 Action. — These little muscles, by drawing the transverse processes towards each oth- 
 er, incline that portion of the vertebral column with which they are connected towards 
 their own side ; that is, the cervical muscles with the rectus lateralis incline the head 
 and neck, and those of the lumbar region act upon the loins. 
 
 The Scaleni. 
 
 Dissection. — These muscles are, in a great measure, displayed in the ordinary dissec- 
 tion of the anterior and posterior cervical regions. In order specially to expose them 
 upon an entire subject, it is sufficient to dissect off the skin on the sides of the neck, and 
 to remove the omo-hyoid, the nerves, the cellular tissue, and the sub-clavicular lymphat- 
 ic glands. But in order to demonstrate the inferior attachments of these muscles, the 
 upper limb must be scarified by disarticulating the clavicle at its sternal end, or, still bet- 
 ter, by sawing the clavicle through the middle, dividing the great and small pectoral mus- 
 cles, raising the stemo-cleido-mastoid, detaching the serratus magnus, and drawing the 
 apex of the shoulder forcibly backward. 
 
 The scaleni occupy the sides and lower part of the neck, extending from the two up- 
 per ribs to the six lower cervical vertebrae, sometimes to the atlas also. They are, there- 
 fore, fasciculated like all the other vertebral muscles. Anatomists are not agreed con- 
 cerning their number. Albinus enumerated five on each side ; Sabatier reduced these 
 to three •, but we agree with M. Boyer, and modern anatomists, in admitting the exist- 
 ence of two only, an anterior and a posterior. M. Chaussier has followed the example of ♦ 
 Riolanus, in describing only one, which he calls costo-trachelien. 
 
 E E 
 
•gJ8 MYOLOGY. 
 
 1. The scalenus anticus {c,figs. 112, 113, and 114) might be termed the anterior lorig in- 
 ter-transversalis colli. Its name sufficiently indicates its triangular shape, though it rathei 
 resembles a cone with the base below and the apex above. 
 
 Aitachments and Direction. — It arises from the inner margin and upper surface of the 
 first rib, near its middle, the point of attachment being indicated by a tubercle, with which 
 it is highly important that we should be acquainted, because it serves as a guide in pla- 
 cing a ligature upon the subclavian artery, which passes over the upper surface of the 
 first rib. It arises by means of a tendon that expands into an aponeurotic cone, from the 
 interior of which the fleshy fibres take their origin. These unite, form the body of the 
 muscle, and proceed upward and inward, to be inserted by so many separate tendons into 
 the anterior tubercles of the transverse processes of the sixth, fifth, fourth, and third cer- 
 vical vertebrae, and more especially into the notches between the two tubercles at the ex- 
 tremities of these processes. It is not unconmfion to find one or two fasciculi inserted 
 into the posterior tubercles. 
 
 Relations. — In front and on the outside, this muscle is in relation with the clavicle, from 
 which it is separated by the subclavian muscle and vein ; higher up, with the stemo- 
 mastoid, the omo-hyoid, the phrenic nerve, and the transverse and ascending cervical 
 arteries. Behind, it is separated from the posterior scalenus by a triangular space, which 
 is wide below to receive the subclavian artery, and narrow above, where it corresponds 
 to the brachial plexus of nerves, by the first two branches of which the muscle is some- 
 times perforated. On the inside, it is separated from the vertebral artery by the longus 
 colli. The relations of the scalenus anticus to the subclavian vein and artery are of the 
 highest importance to the surgeon, and, in order to impress them upon the memory, I 
 propose to designate it the muscle of the subclavian artery. I have seen both the artery 
 and vein placed in front of this muscle. 
 
 The scalenus posticus {d,figs. 112, 113, and 114) may be termed the posterior long inter- 
 transversalis colli. It is situated behind the preceding muscle, is of the same shape, but 
 somewhat larger. 
 
 Attachments and Direction. — It has two perfectly distinct origins : one, anterior and 
 larger, from all that part of the first rib intervening between the depression for the sub- 
 clavian artery and the tubercle ; and another, posterior, from the upper edge of the sec- 
 ond rib. The latter attachment is sometimes wanting. Proceeding from this double 
 origin, the fleshy fibres form two small muscular bodies, which either remain distinct, or 
 become blended together, and pass upward and inward, to be inserted by six separate 
 tendons into the posterior tubercles of the transverse processes of the six inferior cer- 
 vical vertebrae. It is not uncommon to find a fasciculus extending from the second rib 
 to the atlas. 
 
 Relations. — It is separated from the anterior scalenus by the subclavian artery and 
 brachial plexus ; and is in relation, behind, with the cervicaJis descendens, transversalis 
 colli, splenius, and levator anguli scapulae : on the outside, with the serratus magnus, 
 the transverse cervical artery, and the stemo-mastoideus : on the inside, with the first 
 intercostal, the first rib, the inter-transversales of the neck, and the cervical vertebrae. 
 
 Action. — The scaleni are powerful flexors of the neck, when their fixed points are be- 
 low ; but when their upper attachments are fixed, they tend to elevate the first rib, and 
 in a slight degree the second also. 
 
 DEEP ANTERIOR CERVICAL, OR PREVERTEBRAL REGION. 
 
 The Recti Capitis Antici, Major et Minor. — Longus Colli. — Action of these Muscles. 
 
 This region includes three pairs of muscles placed immediately in front of the cervical 
 and three superior dorsal vertebrae, viz., the rectus capitis anticus major, the rectus capi- 
 tis anticus minor, and the longus colli. Their arrangement is extremely complicated and 
 very difficult of elucidation, unless we consider them in the same general manner al- 
 ready adopted with regard to the disposition of the posterior spinal muscles. Let us 
 suppose, then, that there exists in the median line of the basilar process of the occipital 
 bone and the anterior surface of the bodies of the cervical vertebrae a series of spinous 
 processes (a supposition which is realized in some animals) ; then the rectus capitis an- 
 ticus major would be a transverso-spinalis, the rectus minor an anterior inter-transversalis 
 between the occipital bone and the atlas, and the longus colli would be a compound mus- 
 cle, its lower fibres forming a spino-transversalis, its upper fibres a transverso-spinalis, 
 and its internal fibres a spinalis. All this wiU be rendered apparent from the following 
 description. 
 
 Dissection. — Remove the face and all the parts which cover the cervical portion of the 
 spine by the vertical section, called the section of the pharynx, because it is also employed 
 in demonstrating that part. In order to separate the face from the cranium, remove the 
 roof of the scull by a horizontal section, and then make a vertical cut either from above 
 or from below ; if we cut from above, we may adopt the usual plan of directing the saw 
 transversely, so as to emerge immediately in front of the auditorj' meatus : in doing this, 
 
THE RECTUS CAPITIS ANTICUS MAJOR, ETC. "!?t1) 
 
 however, we are in danger of injuring the superior attachments of the recti, or of cutting 
 into the pharynx. We prefer, therefore, the following method : make two sections with 
 the saw obliquely forward and inward in the course of the occipito-mastoid and petro- 
 occipital sutures, and having arrived at the basilar process, cut it across with a chisel, 
 a little in front of the anterior condyloid foramina. In separating the face from the cra- 
 nium from below upward, a great number of muscles must be scarified : the preceding 
 section is therefore preferable, although it is somewhat more difficult. 
 
 The Rectus Capitis Anticus Major. 
 
 This muscle {e,figs. 112 and 114), the transverso-spinalis anterior (rectus capitis in- 
 temus major, Alb.), is the most external of those in the prevertebral region. 
 
 Attachments and Direction. — It arises from the anterior tubercles of the transverse pro- 
 cesses of the sixth, fifth, fourth, and third cervical vertebrae, by small tendons, to which 
 as many fleshy fasciculi succeed ; these pass obliquely upward and inward, overlying 
 and blending with each other, and terminate on the posterior surface and edges of a shi- 
 ning aponeurosis, that occupies almost entirely the anterior aspect of the muscle. This 
 aponeurosis itself becomes a surface of origin, dividing into two lamina;, from the bor- 
 ders of and interval between which a fleshy bundle ascends, to be inserted into the basi- 
 lar process in front of the foramen magnum. The fasciculus arising from the third cer- 
 vical vertebra does not join the common insertion, but is attached directly, and in a very 
 distinct manner, to the basilar process within and behind the common fasciculus. The 
 muscle must be turned outward in order to display this structure. 
 
 Relations. — It is covered by the pharynx, the internal carotid artery and jugular vein, 
 the superior cervical ganglion and trunk of the great sympathetic nerve, and the par va- 
 gum, being separated from all these parts by some loose cellular tissue and the preverte- 
 bral aponeurosis. It covers the corresponding vertebrae, the articulation of the occipital 
 bone with the atlas, and that of the atlas with the axis, a portion of the longus colli, and 
 also of the rectus minor. 
 
 The Rectus Capitis Anticus Minor. 
 
 This muscle {f,fig- 112), the inter-transversalis anterior (re^ctus capitis internus mi- 
 nor, Alh.), extends from the base of the transverse process and from the adjacent part 
 of the lateral mass of the atlas, to the basilar process of the occipital bone. It is partial- 
 ly covered by the rectus major, which is nearer the mesial plane : the superior cervical 
 ganglion of the sympathetic rests upon it, and it covers the atloido-occipital articulation. 
 It may be regarded as an anterior inter-transversalis between the occipitcd bone and the 
 atlas, the rectus laterahs constituting the posterior inter-transversalis. 
 
 The Longus Colli. 
 
 Attachments, Direction, and Relations. — The longus coUi {g,g,figs. 112 and 114), as be- 
 fore stated, is composed of three very distinct sets of fasciculi : 1. The transverso-spina- 
 lis, which, arising by flat tendons from the anterior tubercles of the transverse processes 
 of the fifth, fourth, and third cervical vertebra;, unite so as to form a considerable fleshy 
 bundle directed upward and inward, occupy the hollow on each side of the median line 
 of the axis, and are inserted into the anterior tubercle of the atlas, which may be regard- 
 ed as the representative of an anterior spinous process : 2. The anterior spino-transver- 
 salis, the least numerous of all, arise from the bodies of the three superior dorsal verte- 
 brae by very slight tendinous expansions, proceed upward and outward, and are inserted 
 into the anterior tubercles of the transverse processes of the fourth and third cervical 
 vertebrae : 3. The spinalis which arise, to the inner side of the preceding fasciculi, from 
 the bodies of the three upper dorsal and four lower cervical vertebrae, and from the in- 
 termediate ligaments, and having described a slight curve, are inserted into the crest of 
 the axis and into the third cervical vertebra. The longus colli is elongated and fusiform 
 in shape ; it supports the pharynx, the oesophagus, the internal carotid artery, the inter- 
 nal jugular vein, and the pneumogastric and great sympathetic nerves : it covers the 
 vertebrae to which it is attached. 
 
 Action of the Muscles of the deep Anterior Cervical Region. 
 
 When the head is thrown back, these muscles restore it to its original position. The 
 rectus anticus major tends to flex the head, and from its obliquity to rotate it, so as to 
 turn the face to its own side. The rectus minor inclines the head to its own side. The 
 longus colli flexes the atlas upon the axis, and rotates it so as to turn the face to its own 
 Bide. '^I'he same muscle also rotates the lower part of the neck, so as to turn the face 
 to the opposite side • and, lastly, it is a direct flexor of the cervical region. 
 
MYOLOGY. 
 
 THORACIC REGION 
 
 The Pectoralis Major. — Pectoralis Minor. — Subclavius. — Serratus Magnus. — Intcrcostales 
 — Supra-costales. — Infra-costales. — Triangularis Sterni. 
 
 The Pectoralis Major. 
 
 Dissection. — Separate the arm from the side. Make a horizontal incision from the top 
 of the sternum to the front of the arm on a level with the lower border of the axilla, in- 
 cluding in this incision a fascia which adheres closely to the fleshy fibres. Reflect one 
 of the flaps upward and the other downward, by dissecting parallel to the fibres, i. e., 
 transversely to the axis of the body. 
 
 The ■pectoralis major (c c, fig. 109) is a broad, thick, triangular muscle, situated at the 
 upper and fore part of the thorax and axilla. It arises from the anterior border of the 
 clavicle and anterior surface of the sternum, from the cartilages of the second, third, 
 fourth, and more particularly those of the fifth and sixth ribs, from the osseous portion 
 of the last-mentioned rib, and from the abdominal aponeurosis : it \s inserted into the an- 
 terior margin of the bicipital groove of the humerus. 
 
 The clavicular origin consists of short tendinous fibres attached to the entire breadth 
 of the anterior border of the clavicle, for about the inferior third, or half of its extent. 
 
 The sternal attachment consists of aponeurotic fibres, which, intersecting with those of 
 the opposite muscle, form, in front of the sternum, a very thick fibrous layer, sometimes 
 ahnost completely covered by the muscular fibres, which, in certain individuals, advance 
 nearly to the median line. 
 
 The costal origins consist of very thin tendinous laminae, and the attachment to the 
 abdominal aponeurosis is blended with that of the rectus abdominis. 
 
 From these different origins the fleshy fibres proceed outward in different directions ; 
 the upper fibres obliquely downward, the middle transversely, and the lower fibres oblique- 
 ly. These last are folded backward, so as to form a sort of groove, which embraces the 
 lower border of the pectoralis minor. It appears, then, that the pectoralis major is com- 
 posed of three very distinct portions, which are sometimes separated by a greater or 
 less quantity of cellular tissue. These three portions, in converging, are so disposed that 
 the upper overlaps the middle, and this, again, the lower portion, the fibres of which are 
 twisted upon themselves, so that the lowest in front become the highest behind, and vice 
 versa.* They are all inserted into the anterior lip of the bicipital groove by means of a 
 flat tendon, about fifteen lines in breadth, which is continuous with the anterior edge of 
 the tendon of the deltoid. The structure of this tendon commands particular attention, 
 and can only be examined after having divided the muscle across, and turned the exter- 
 nal half outward. It will then be seen that it is composed of two laminae, placed one be- 
 fore the other, sometimes blended together, but generally distinct, or united only by 
 their lower edges, so that they form a groove opening upward. The anterior lamina is 
 the thicker, and receives the clavicular and middle portions of the muscle ; the deep lay- 
 er affords attachment to the lower portion. It is not uncommon to find the two laminae 
 separated by the tendon of the long head of the biceps, the groove for which they then 
 contribute to form. The entire tendon is broader and thicker below than above, and 
 gives off, both forward and backward, an aponeurotic expansion, constituting one of the 
 chief origins of the fascia of the arm.t 
 
 Relations. — It is covered by the platysma myoides, the mammary gland, and the skin. 
 Its deep relations are of the greatest importance. On the thorax it covers the sternum, 
 the ribs and their cartilages, the pectoralis minor, the subclavius nauscle, the serratus 
 m£ignus, and the intercostals. It forms the anterior wall of the axilla, and is in relation 
 with the brachial plexus and axillary vessels, and with the cellular tissue and lymphatic 
 glands of that region. Its external border is nearly parallel to the anterior edge of the 
 deltoid, being separated from the latter by a linear or triangular cellular interval, in 
 which are situated the cephalic vein and acromial artery. Its lower border is thin towards 
 the median line, thick and tendinous externally ; it forms the anterior border of the ax- 
 illa, and gives rise to a projection under the skin, proportionate to the development of the 
 muscle. Its inner border intersects in the median line with the muscle of the opposite 
 side, and is continuous below with the linea alba. 
 
 Uses. — The pectoralis major is essentially an addTictor of the arm ; at the same time it 
 rotates it inward, and draws it forward. It is by the action of this muscle that the fore- 
 arms are crossed, and that one hand is placed on the opposite shoulder. Its upper or 
 clavicular portion conspires with the anterior fibres of the deltoid and with the coraco- 
 brachialis in elevating the humerus, and carrying it forward. 
 
 * I believe that this overlapping and folding of the muscular fibres tend, reciprocally, to prevent the dis- 
 placement of any individual portion of the muscle. 
 
 t I have once observed a very slender muscular fasciculus, arising' from the abdominal aponeurosis, proceed 
 along the inferior border of the pectoralis major, from which it was perfectly distinct, and terminate in a small 
 tendon opposite the humeral insertion of that muscle. This tendon was continued along- the inner side of the 
 arm, adhered to the aponeurotic inter-muscular septum, from which it received a small fleshy fasciculus, and 
 was ultimately inserted into the epitrochlea 
 
IHB FECTORALIS MINOR, SUBCLAVIUS, AND SERRATUS MAGNUS. 2l2t 
 
 If the arm be at a moderate distance from the side and its lower extremity be fixed, 
 as is the case in falling on the elbow when the arm is directed outward, this muscle acts 
 upon the humerus as upon a lever of the third order, of which the fulcrum is below, the pow- 
 er in the middle, and the resistance above ; and it then tends to dislocate the bead of the 
 humerus •with great force, because in this position its insertion is perpendicular to the lever. 
 
 When the humerus is fixed, the pectoralis major acts upon the ribs, the sternum, and 
 the clavicle, and raises the trunk upon the arm. It is, therefore, one of the chief agents 
 in climbing. Its action upon the ribs renders it an important auxiliary in cases of la- 
 borious inspiration. Hence the attitude of an asthmatic patient, who always nlaces him- 
 self so as to keep the humeri fixed. 
 
 The Pectoralis Minor. 
 
 Dissection. — Detach the clavicular insertion of the pectoralis major, and divide that 
 muscle in the middle by a verticle incision ; reflect the two flaps, taking care to remove, 
 at the same time, the loose cellular tissue which invests its deep surface. 
 
 The pectoralis minor {t,fi.g. 110) is a thin, flat, triangular muscle, having its internal 
 edge serrated (serratus anticus, Albinus), and occupying the anterior and upper part of 
 the thorax and shoulder. It arises from the third, fourth, and fifth ribs, by three delicate, 
 shining, tendinous prolongations, lying superficially to the intercostal muscles ; to these 
 succeed three fleshy fasciculi, which unite and converge, so as to be inserted by a flat 
 tendon into the anterior margin of the coracoid process, near its summit. 
 
 Relations. — It is covered by the pectoralis major, from which it is separated by the tho- 
 racic vessels and nerves : its posterior surface is in relation with the ribs, the intercos- 
 tal muscles, the serratus magnus, the cavity of the axilla, and, therefore, with the axillary 
 vessels and nerves. This last relation is of great importance, and sometimes renders 
 the section of this muscle necessary for the ligature of the axillary artery. Attention 
 should also be directed, 1 . To its upper border, which is separated from the clavicle by 
 a triangular interval, broad on the inside and narrow on the outside, in which the same 
 artery may be tied ; and, 2. The lower border of the muscle extends downward beyond 
 the pectoralis major. 
 
 Action. — Most commonly it acts upon the scapula (musculus qui scapulam antrorsum 
 agit, Vesalius). With its fixed point at the ribs, it evidently draws the scapula forward 
 and downward, and forcibly depresses the apex of the shoulder. As a depressor of the 
 shoulder, it acts in conjunction with the levator anguli scapulae and rhomboideus, but an- 
 tagonizes those muscles considered as elevators of the entire scapula : it is also opposed 
 to the rhomboideus when moving the scapula forward. With its fixed point at the scapu- 
 la, this muscle elevates the ribs to which it is attached. 
 
 The Subclavius. 
 
 Dissection. — Raise the clavicle by carrying the apex of the shoulder upward ; divide 
 the pectoralis minor, and remove the fibrous membrane, descending from the clavicle, 
 and immeidiately investing the muscle. In order to expose its external or clavicular in- 
 sertion, saw through the clavicle in the middle, divide the muscle at the same point, and 
 reflect the external half with the corresponding portion of the clavicle. 
 
 The subclavius (g,fig. 110) is a long, thin, fusiform muscle, applied to the lower sur- 
 face of the clavicle, by which it is concealed (musculus qui sub clavicula occultatur, Fa- 
 bricius Hildanus). It arises from the cartilage of the first rib, and is inserted into the in- 
 ferior and external surface of the clavicle. Its costal attachment consists of a cervical 
 tendon, from which the fleshy fibres proceed outward, backward, and upward, and are in- 
 serted into the clavicle by short, tendinous fibres. 
 
 Relations. — It is covered above by the clavicle, which is grooved beneath for its recep- 
 tion ; it is in relation below with the first rib, being separated from it by the axillary ves- 
 sels and the brachial flexus ; in front, it is enveloped by a very strong aponeurosis, com- 
 pleting the osteo-fibrous canal in which it is included. Its relation with the brachial 
 plexus and axillary vessels prevents the direct compression to which these parts would 
 have been otherwise exposed between the clavicle and the first rib. 
 
 Action. — ^When its fixed point is at the first rib, it depresses the clavicle, and is, there- 
 fore, a depressor of the shoulder ; it tends also to press the inner end of the clavicle for- 
 cibly against the sternum ; so, also, in fracture of the clavicle, it occasions the external 
 fragment to ride upon the internal. When its fixed point is at the clavicle, it assists in 
 elevating the first rib, and is, therefore, arranged among the muscles that act in impeded 
 inspiration. 
 
 The Serratus Magnus. 
 Dissection. — Having removed the two pectorals, saw through the clavicle at its mid- 
 dle ; press the scapula backward, directing its axillary edge outward ; remove with care 
 the cellular tissue occupying the axilla, especially that against the axillary vessels and 
 nerves, and near the intercostal attachments of the muscle itself, in order to see the in- 
 ternal surface of which the subject must be turned, and the vertebral eosta of the scap- 
 ula drawn outward. 
 
222 XM.i* - MYOLOGY. 
 
 The serratus magnus [u,fig. 106, d, 109, and I, 110), very broad, quadrilateral, and ser- 
 rated along one of its borders, occupies the side of the thorax, and extends, hke a mus- 
 cular girth, from the ten upper ribs to the vertebral costa of the scapula. Its costal at- 
 tachments consist of nine or ten digitations arranged in a curve, having its concavity di- 
 rected backward. The first digitation, which is very large, arises both from the first 
 and second ribs, and from an aponeurotic arch between them ; from thence tlie fibres 
 proceed upward, outward, and backward, and are inserted into the inner surface of the 
 posterior and superior angle of the scapula, near the levator anguli. This digitation is 
 the narrowest part of the muscle ; it differs in direction from the remainder, and is sep- 
 arated from them by a cellular interval ; hence it has been termed the superior portion 
 of the serratus magnus. The second, third, and fourth digitations arise in an oblique 
 line, running downward and forward from the second, third, and fourth ribs. These are 
 the largest and the thinnest of all the digitations ; they proceed horizontally backward, 
 and are inserted separately, by short tendinous fibres, into the entire length of the verte- 
 bral costa of the scapula, anterior to the rhomboid ; they are distinguished from the re- 
 maining digitations both by their direction and by an intervening cellular space ; they 
 form the middle portion of the serratus magnus. 
 
 The fifth, sixth, seventh, eighth, ninth, and tenth digitations arise from the outer sur- 
 face of the corresponding ribs along oblique lines, resembling the fingers crossed, and 
 are interposed between corresponding prolongations of the external oblique. These di- 
 gitations are at first tendinous ; they soon become fleshy, and, converging towards each 
 other, form a radiated fasciculus, which passes upward, outward, and backward, to be 
 inserted into the internal surface of the inferior angle of the scapula. This is the infe- 
 rior portion of the serratus magnus. 
 
 Relations. — The serratus rnagnus is partially covered by the two pectorals before, by 
 the subscapularis behind, and above by the axillary vessels and nerves ; its deep surface 
 rests upon the ribs and the intercostal spaces, all these parts being united by a quantity 
 of loose cellular tissue. A considerable portion of the lower part of the muscle is sub- 
 cutaneous, and, therefore, the inferior digitations are important studies for the painter 
 and the sculptor, and sometimes even for the surgeon, as indications of the arrangement 
 of the corresponding ribs. 
 
 Action. — From the disposition of its different fasciculi, the serratus magnus occasions 
 a compound movement of the scapula, which it will be well to analyze. The upper por- 
 tion depresses and brings forward the apex of the shoulder ; the middle portion draws 
 the entire scapula directly forward ; while the lower portion depresses it, and, more- 
 over, rotates it, so that the apex of the shoulder is carried upward. As the lower part 
 of the muscle is composed of six or seven of the converging fasciculi, which act with 
 greater energy than the others, it follows that their action predominates even when the 
 whole muscle contracts. The serratus magnus is, then, a depressor of the entire shoulder, 
 and an elevator of its apex. It is more especially concerned than any other muscle in 
 supporting a burden upon the shoulder. 
 
 In order that the action of the serratus may be directed upon the scapula, its costal 
 attachments must be fixed : this requires the simultaneous contraction of the oblique 
 muscles of the abdomen to maintain the ribs in a depressed position, and of the dia- 
 phragm and transversalis to prevent their projection outward. This simultaneous con- 
 traction occurs during all great efforts. 
 
 When the fixed point of the serratus magnus is at the scapula, its upper portion be 
 comes a muscle of inspiration, its middle one of expiration, and its lower one of inspira 
 tion. The greater power of the latter has been the cause of the antagonizing action of 
 the middle portion being overlooked ; and the serratus magnus is, with great justice, re 
 garded as the most powerful accessory muscle of inspiration : hence the various atti- 
 tudes of asthmatic persons, who instinctively take a position which fixes the scapula, 
 either by seizing a cord suspended from the top of the bed, or by bending forward, anc" 
 leaning on their elbows and forearms, or by resting their upper extremities on two lat 
 eral supports. 
 
 The Inter-costales, Externi and Interni ; the Supra-costdles and the Infra 
 
 costales. 
 
 Dissection. — In order to examine the extemeil intercostals and the supra-costales (le 
 vatores costarum), the scapula and all the muscles which cover the thorax must be re 
 moved ; to expose the internal inter-costales and the infra-costales, it is necessary to 
 saw through the middle of the dorsal vertebrae and the sternum in a vertical direction, 
 and to tear off the pleura from one side of the thorax, which may be very easily accom 
 plished by the fingers. 
 
 The intercostal muscles, as their name implies, occupy the intervals between the ribs 
 there are two in each intercostal space, and, therefore, as many pairs as there are spaces. 
 
 They are divided into external and internal. They represent two very tliin muscular 
 layers, of exactly the same width as the spaces to which they belong ; taken together. 
 
THE INTER-COSTALES, SUPRA-COSTALES, AND INFRA-COSTALES. 223 
 
 they also occupy the entire length of those spaces, but not separately, for the external 
 intercostals extend only from the costo-vertebral articulations to the commencement of 
 the cartilages of the ribs, while the internal intercostals commence at the angles of the 
 ribs behind, and extend forward to the sternum. A very thin aponeurosis is prolonged 
 from the free margin of the one forward and of the other backward to the end of the in- 
 tercostal space. The external muscles, which I have generally found thicker than the 
 internal, arise from the lip of the groove on the lower border of one rib, and the internal 
 from the inner hp of the same groove, as well as from the corresponding costal carti- 
 leige ; they are both inserted into the upper border of the rib below. The superior at 
 tachments consist of fleshy and tendinous fibres and lamellae, all of which proceed down- 
 ward to the rib below ; those of the external layer obliquely forward, and those of the 
 internal layer much l6ss obliquely backward. The inferior attachments are similar in 
 structure. The tendinous fibres of the intercostal muscles are very long, and much 
 more numerous than the fleshy fibres : hence the intercostal spaces possess consider- 
 able strength, to which the crossing of the two layers also contributes. 
 
 Relations. — The external intercostals are covered by the two pectorals, the serratus 
 magnus, the serrati postici, the latissimus dorsi, the sacro-lumbalis, and the external ob- 
 lique ; they are superficial to the internal intercostals, and are separated from them by the 
 intercostal vessels and nerves, and by a very thin fibrous layer. The internal intercostala 
 are covered by the external and by the aponeurotic layer continuous with them anterior- 
 ly. Internally they are in relation with the pleura, which, from the angles to the tuber- 
 osities of the ribs, is in apposition with the external muscles. 
 
 The infracostal muscles of Verheyen consist of small muscular and aponeurotic tongues, 
 variable in number and length, which extend from the inner surface of one rib to the in- 
 ner surface of the next, and sometimes, also, to the second or third rib below. They are 
 sometimes vertical, but often oblique, like the internal intercostals, of which they may 
 be regarded as portions. 
 
 Supra-costales (levatores breviores costarum of Alhinus, o to o,fig. 107). These are 
 small triangular muscles, situated at the back part of the intercostal spaces. They are 
 accessories of the external intercostals, resemble them in being half tendinous and half 
 fleshy, and appear to form a continuation of them. There are twelve on either side. 
 Each arises from the summit of the transverse process of a vertebra, and proceeds in a 
 radiated manner downward, to be inserted into the back part of the upper border and ex- 
 ternal surface of the rib below. 
 
 The fibres of these muscles have the same direction as those of the external intercos- 
 tals, but they are more obhque, especially on the outside. The first arises from the trans- 
 verse process of the seventh cervical vertebra, the last from that of the eleventh dorseil. 
 Some of these muscles have two digitations, one disposed in the ordinary manner, the 
 other attached to the next rib below. The latter, called the long supra-costals (levatores 
 longiores, Albinus and Haller), form a transition between the levatores breviores and the 
 serrati. Morgagni met with all the levatores united together, so as to form a very reg- 
 ular serrated muscle. They are covered by the longissimus dorsi and sacro-lumbaUs, 
 and they cover the external intercostals. 
 
 Action. — The contraction of the intercostal muscles tends to approximate the ribs ; 
 and, according as the upper or the lower ribs are fixed, they act as muscles of inspira- 
 tion or of expiration. It has never been denied that the external intercostals are mus- 
 cles of inspiration, but the crossing of the tAvo muscidar layers has given rise to the opin- 
 ion that they oppose each other in action ; and hence arose the celebrated dispute be- 
 tween Bamberger and Haller. It is easy to understand that the slight difference exist- 
 ing between their attachments, with regard to their distance from the fulcrum, could not 
 counterbalance the effect of a difference in the relative fixedness of the ribs, and that the 
 intercrossing of these muscles has no other object than to increase the strength of the 
 parietes of the thorax. 
 
 As the first rib is much more fixed than the last, it follows that it must serve as a fixed 
 point for the first intercostal muscle, which will consequently raise the second rib ; this 
 will then become the fixed point for the third rib, and so on. The scaleni off^en take their 
 fixed point upon the vertebrae, and then assist in elevating the first rib. The quadratus 
 lumborum depresses the last rib, which may then serve as a fixed point for the others 
 during expiration. 
 
 The levatores act very effectually in raising the ribs ; for, being attached so near to 
 the fulcrum, the slightest movement produced in the posterior extremity of the rib be- 
 comes very sensible at the other end. I agree with Borelli {De Motu Animal., torn, ii-, 
 p. 158), that the intercostals act even during the most easy respiration. This can be 
 observed upon our own persons, and also in individuals in deep sleep. The ribs will 
 be seen distinctly carried outward, and the sternum raised. 
 
 The Triangularis Sterni, or small Jlnterior Serratus. 
 Dissection. — Divide the ribs vertically at their junction with the cartilages, and tear 
 off" the plenra with the fingers. 
 
224 .i/.(K. :v -'^X- ^" MYOLOGY. '""^ 
 
 The triangularis sterni represents the levatores costarum in front, or, rather, the ser- 
 rati postici, with this difference, that it occupies the internal instead of the external sur- 
 face of the thorax. Like them, it is sen-ated. It arises from the sides of the posterior 
 surface of the sternum, from the ensiform cartilage and the inner ends of the cartilages 
 ■ of the ribs. From this origin the fleshy fibres proceed, dividing into three, four, five, and 
 sometimes six digitations, which are inserted by tendinous fibres into the posterior sur- 
 face and borders of the sixth, fifth, fourth, third, sometimes of the second, and even of 
 the first costal cartilages. The lower fibres pass horizontally and parallel to the upper 
 fibres of the transvcrsalis, with which they are continuous. The succeeding fibres are 
 directed upward and outward, proceeding more and more obliquely upward : hence the 
 triangular shape of the muscle, to which its name refers. 
 
 Relations. — It is covered by the sternum, the internal intercostal muscles, and the cos- 
 tal cartilages, from which it is separated by the manunary vessels and some lymphatic 
 glands ; it is lined internally by the pleura, and rests upon the diaphragm below. 
 
 Its use is evidently to depress the costal cartilages, into which it is inserted, or to op- 
 pose their elevation. 
 
 Remarks concerning the Intercostal Muscles. — The muscles we have just described, viz., 
 the intercostals and" their accessories, are essential elements in the construction of the 
 chest ; they are found in all animals possessed of a thorax. Their use is to dilate and 
 contract this cavity in its antero-posterior and transverse diameters. The first rib, be- 
 ing Itxed by the contraction of the scaleni, serves as a fulcrum for the agents of inspira- 
 tion ; and the last rib, when fixed by the quadratus lumborum, serves the same purpose 
 for those of expiration ; so that these muscles, whose most common action is to incline 
 to one side the neck and the loins, do not, on that account, act the less u^jon the ribs. 
 I cannot, by any means, agree with Winslow, who denies that the scaleni have any ac- 
 tion upon the ribs, and maintains that the articulation of the first rib with the first dor- 
 sal vertebra is intended for the movement of the vertebra on the rib, not for that of the 
 rib on the vertebra. (Winslow, Expos. Anat., t. ii., p. 360.) 
 
 SUPERFICIAL ANTERIOR CERVICAL REGION. 
 TAe Platysma Myoides. — Sterno-cleido-mastoideus. 
 
 The Platysma Myoides. 
 
 Dissection. — Stretch the muscle by inclining the head backward and placing a block 
 under the shoulders of the subject ; make a horizontal incision through the skin from the 
 angle of the jaw to the symphysis menti, another from the symphysis to the inner end 
 of the clavicle, and a third along the clavicle. These incisions should be very super- 
 ficial, scarcely dividing the entire thickness of the skin. The muscle must be very cau- 
 tiously dissected by taking care to commence at its upper part, to turn the edge of the 
 scalpel towards the skin, and to follow exactly the direction of the fleshy fibres which 
 pass obliquely downward and outward. 
 
 The platysma myoides (e, fig. 109), called le pcaucier by Winslow, latissimus colli by AI- 
 binus, is a broad, very thin, and irregularly-quadrilateral muscle lining the skin at the 
 fore part of the neck, and adhering to it like the cutaneous muscles of the lower animals. 
 It extends from the skin covering the anterior and upper part of the thorax to the side ' 
 of the face, where it terminates thus : at the base of the lower jaw, at the commissure 
 of the lips, upon the masseter muscle, and at the skin of the face. From its lower at- 
 tachment, which is almost always prolonged as far as the shoulder, and loses itself in 
 the subcutaneous cellular tissue, the fibres proceed obliquely upward and inward ; the 
 pale muscular fasciculi which they form are separated from each other, and sometimes 
 strengthened by additional fasciculi to the posterior border of the muscle : they terminate 
 in the following manner above : the posterior fibres are lost under the skin of the face 
 near the masseter muscle, the lower end of which they cover ; those next in front are 
 partly continuous with the triangularis oris, and partly with the quadratus menti ; the 
 anterior fibres terminate at the external oblique line of the lower jaw, and the most in- 
 ternal intersect with those of the opposite side. The posterior fibres, which are lost 
 upon the skin of the face, are the rudiments of a remarkable fasciculus, an accessory of 
 the platysma found in some subjects. It is directed obliquely downward, from the re- 
 gion of the parotid gland to the angle of the lips. Santorini described it under the name 
 ofrisorius novus. 
 
 Relations. — These two muscles occupy the whole anterior region of the neck, except- 
 ing the median line, where they leave a triangular interval, having its base below, and 
 occupied by a very dense fibrous tissue, forming a species of raph(5, which is found in the 
 median line throughout the body. This is the linea alba of the neck, from which the dif- 
 ferent component layers of the cervical fascia take their origin. 
 
 The platysma is intimately connected with the skin, but it does not adhere equally 
 throughout ; it is united closely below, but much more loosely above, where the inter 
 
THE STERNO-CLEIDO-MASTOIDEUS. 
 
 225 
 
 ▼enmg cellular tissue is always adipose, and capable of containing a large quantity of 
 fat, as we find in individuals who have what is called a double chin. There are no lym- 
 phatic glands between this muscle and the skin ; they are all situated beneath the mus- 
 cle. The relations of the deep surface of the platysma are very numerous. It covers 
 the supra and sub-hyoid, and the supra-clavicular regions, being separated from all the 
 structures beneath it by the cervical fascia, to which it is united by loose cellular tissue, 
 seldom containing any fat. If we examine these relations in detail, we find, proceeding 
 from below upward, that it covers, 1. The clavicle, the pectoralis major, and the deltoid ; 
 2. In the neck, the external jugular vein, and also the anterior jugulars where they ex- 
 ist, the superficial cervical plexus, the sterno-mastoid, the omo-hyoid, the sterno or cle- 
 ido hyoid, the digrastic, and the mylo-hyoid muscles, the sub-maxillary gland, and the 
 lymphatic glands at the base of the jaw. In front of the sterno-mastoid, it covers the 
 common carotid artery, the internal jugular vein, and the pneumogastric nerve ; behind 
 the sterno-mastoid, it covers the scaleni muscles, the nerves of the brachial plexus, and 
 some of the lower nerves of the cervical plexus. 3. In the face, it covers the external 
 maxillary or facial artery, the masseter and buccinator muscles, the parotid gland, &c. 
 
 Action. — The platysma is the most distinctly marked vestige in the human body of the 
 panniculus carnosus of animals ; and it can produce slight wrinkles in the skin of the 
 neck. Its anterior border, especially at its insertion near the symphysis menti, is the 
 thickest part of the muscle, and therefore projects slightly during its contraction. It is 
 one of the depressors of the lower jaw ; it also depresses the lower lip, and, slightly, the 
 commissure of the lips. It therefore assists in the expression of melancholy feelings, 
 but it is antagonized by the accessory portion, which draws the angle of the lips upward 
 and a little outward, and thus concurs in the expression of pleasurable emotions ; hence 
 its name, risorius. 
 
 The Sterno-cleido-mastoideus. 
 
 Dissection. — Divide the skin and the platysma from the mastoid process to thewtop of 
 the sternum, in an oblique line, running downward and forward ; reflect the two flaps, 
 one forward and the other backward, taking care to remove at the same time the strong 
 fascia which covers the muscle. In order to obtain a good view of the superior attach- 
 ments, make a horizontal incision along the superior semicircular line of the occipital bone. 
 
 The sterno-cleido-Tnastoid {b, Jig. 113) occupies the anterior and lateral regions of the 
 neck. It is a thick muscle, bifid below, and narrower in the middle than at either end. 
 It arises, by two very distinct masses, from the inner end of the clavicle, and from the 
 top of the sternum in front of the fourchette, and is inserted into the mastoid process 
 and the superior semicircular line of the occipital bone. The sternal origin consists of 
 a tendon prolonged for a considerable distance in front of the fleshy fibres. The clavic- 
 ular origin consists of very distinct parallel ten- pig. 113. 
 dinous fibres, attached to the^ inner side of the 
 anterior edge and upper surface of the clavicle, 
 to a very variable extent, an important fact in 
 surgical anatomy. There is often a considerable 
 cellular interval between these two origins ; 
 sometimes this interval scarcely exists, but, in 
 all cases, the two portions of the muscle can be 
 readily separated. From this double origin the 
 fleshy fibres proceed, forming two large bundles, 
 which rfimain distinct for some time. Many 
 anatomists, therefore, Albinus in particular, have 
 considered it as consisting of two separate mus- 
 cles, which they describe as the sterno-mastoid 
 and the cleido-mastoid ; a division that is sanc- 
 tioned by the comparative anatomy of this mus- 
 cle. The sternal portion of the muscle is the 
 larger, and passes upward and outward ; the cla- 
 vicular portion proceeds almost vertically upward, 
 behind the other, and is entirely concealed by it 
 at the middle of the neck ; the two portions still 
 remain separate, although approximated ; ulti- 
 mately they become united, and are inserted into 
 the apex and anterior surface of the mastoid pro- 
 cess by a very strong tendon, which runs for 
 some distance along the anterior border of the 
 muscle, and also into the two external thirds of 
 he superior semicircular line of the occipital bone, by a thin aponeurosis. The direction- 
 or axis of the sterno-mastoid passes obliquely upward, backward, and outward. 
 
 The relations of this muscle are very important. Its superficial or external surface is 
 covered bv the skin and platysma, from which it is separated by the external jugulai' 
 
 Fy 
 
226 MYOLOGY. 
 
 vein, and the branches of nerves, constituting what is improperly termed the superficial 
 cervical plexus. Its deep or internal surface covers, 1. The sterno-clavicular articulation ; 
 2. All the muscles of the sub-hyoid region, and also the splenius, the levator anguli scap- 
 ulae, the digastricus, and the scaleni ; 3. The accessory nerve of Willis, which crosses 
 beneath its superior third, the pneumo-gastric nerve, the great sympathetic, the loop of 
 the hypoglossal nerve, and the cervical nerves ; 4. The internal jugular vein ; 5. The 
 lower portion of the common carotid artery. Its anterior border produces a ridge under 
 the skin, which it is important to study, because the first incisions for hgature of the 
 common carotid, and for oesophagotomy, should be made along it. The parotid gland 
 rests upon the upper part of this border, which is separated from the corresponding bor- 
 der of the muscle of the opposite side by a triangular interval, of which the apex is be- 
 low and the base above. Its posterior border forms the anterior limits of the lateral tri- 
 angle of the neck, which is bounded behind by the external margin of the trapezius, and 
 below by the clavicle. 
 
 Action. — When the sterno-cleido-mastoid of one side acts alone, it flexes the head, in- 
 clines it to its own side, and rotates it so that the face is turned to the opposite side. It 
 is, therefore, both a flexor and a rotator of the head. When both muscles act together, 
 they flex the head directly upon the neck, and the neck upon the chest. Their action is 
 particularly manifested in an attempt to raise the head while lying upon the back. Still, 
 there is a position in which this muscle may become an extensor of the head, viz., when 
 it is thrown very far backward ; and this effect is owing to the nature of the upper inser- 
 tion, which is situated somewhat behind the fulcrum of the lever represented by the head. 
 
 This muscle affords one of the most remarkable examples of the co-operation or si- 
 multaneous action of several muscles, in order to give effect to the action of one. Thus, 
 in order that the sterno-cleido-mastoid may act most advantageously upon the head, it 
 becomes necessary that the sternum, being the fixed point, should be maintained as im- 
 movable as possible, and this can only be effected by the contraction of the recti muscles 
 of the abdomen. These latter, in their turn, require a fixed point at the pelvis, and this 
 renders necessary the contraction of the glutaei, the semi-tendinosus, the semi-mem- 
 branosus, and biceps femoris on either side ; and, lastly, for the action of these, the legs 
 require to be fixed by means of their extensor muscles. 
 
 This remarkable simultaneous contraction of so many muscles, necessary for the ac- 
 tion of but one, has been extremely well illustrated by Winslow. It has many impor- 
 tant results both in physiology and in pathology. 
 
 MUSCLES OF THE INFRA-HYOID REGION. 
 
 The Stcrno-hyoideus. — Scapula- or Omo-hyoideus. — Sterno-thyroideus. — Thyro-hyoideus. 
 
 The muscles of the infra-hyoid region are four in number«on each side, viz., the sterno, 
 or, rather, cleido-hyoid, the omo-hyoid, and the sterno-thyroid, which is continuous above 
 witli the fourth muscle, viz., the thyro-hyoid. 
 
 The Sterno-hyoideus. 
 
 Dissection. — This is extremely easy, and is the same for all the muscles of this region. 
 Tlie only caution necessary is, that the clavicular and sternal attachments of these mus- 
 cles should be studied from their posterior aspect only, and that the trapezius must be 
 removed in order to expose the scapular attachments of the omo-hyoid. 
 
 The sterno-hyoid [I, figs. 113 and 114) is a flat, thin, riband-like muscle, which is some- 
 times double on each side. It arises from the inner end of the clavicle, and is inserted 
 into the os hyoides. Its inferior attachment is liable to some variations ; most conmion- 
 ly it is connected with the back part of the inner extremity of the clavicle and with the 
 inter-articular cartilage ; sometimes with the outer side of that extremity ; and sometimes 
 with the circumference of the clavicular surface of the sternum. From this origin the 
 fleshy fibres proceed parallel to each other, upward and inward, to be inserted by short 
 tendinous fibres into the lower edge of the body of the os hyoides on the side of the 
 median line, and to the inside of the omo-hyoid, with which it is often blended. Imme- 
 diately above the clavicle this muscle is often divided by an aponeurotic intersection, 
 which is united to that of the opposite side, and forms, as it were, a transverse bridle. 
 
 Relations. — It is covered by the platysma, the stemo-mastoid, and the cervical fascia. 
 It covers the deep-seated muscles, the thyroid body, the crico-thyroid and thjTO-hyoid 
 membranes, from which it is often separated by a bursa mucosa, the crico-thyroid mus- 
 cle, and the superior thyroid artery. The inner edges of the two sterno-hyoid muscles 
 are generally separated by a fibrous raphe, but they are sometimes blended together, and 
 thus render the operation of tracheotomy more difficult. This impediment may, how- 
 ever, be overcome by keeping accurately in the median line. 
 
 The Scapulo- or Omo-hyoideua. 
 This muscle (coraco-hyoideus, Albinus, m m, figs. 113 and 114) is longer and more 
 
THE STERNO-THYROIDEUS AND THYRO-HYOIDEUS. 227 
 
 slender than the preceding ; it is a digastric reflected muscle, composed of two small 
 fleshy bellies, united by an intermediate tendon. It arises from the superior border of 
 the scapula behind the coracoid notch, over an extent varying from a few lines to an 
 inch, and is inserted into the lower part of the body of the os hyoides, externally to the 
 sterno-hyoid. From its origin, which is sometimes tendinous, it proceeds for a variable 
 distance behind and parallel to the clavicle, and is then reflected upward and inward, at 
 an obtuse angle. At the point of reflection it becomes entirely or partially tendinous, 
 and gives origin to another fleshy bundle larger than the former, which is inserted into 
 the OS hyoides. 
 
 The angular direction of this muscle is maintained by means of an aponeurosis, first 
 described by Soemmering, which extends between the inner borders of the two muscles, 
 and is fixed to the clavicle : it is one of the layers of the cervical fascia, an important 
 structure, to be again alluded to hereafter, and of which the omo-hyoid muscles are ten- 
 sors. These muscles eire occasionally wanting ; sometimes they are double. In one 
 case of this kind the accessory muscle was larger than the normal one, and arose from 
 the upper and internal angle of the scapula. 
 
 Relations. — This small muscle, before reaching the sub-hyoid region, traverses two 
 others, the supra-clavicular and the stemo-mastoid. It is covered by the trapezius, the 
 subclavius, the clavicle, the platysma, the stemo-mastoid, and the skin ; it covers the 
 scaleni, the brachial plexus, the internal jugular vein, and the common carotid artery, 
 and it is in contact with the outer border of the sterno-hyoid muscle. 
 
 The Sterno-thyroideus. 
 
 The sterno-thyroid (w. Jig. 1 14) closely corresponds with the sterno-hyoid, from which 
 it differs only in being shorter and broader. It extends from the posterior surface of the 
 sternum to the thyroid cartilage. It arises from the sternum opposite the first rib ; it is 
 often blended with its fellow, so that their origins form a line reaching the entire breadth of 
 the sternum, and often to the edges and posterior surface of the cartilage of the first rib. 
 
 From this origin the fleshy fibres proceed directly upward parallel to each other, and 
 are inserted into the thyroid cartilage by a tendinous arch running obliquely downward 
 and inward, which embraces the thyro-hyoid muscle, and is attached by its extremities 
 to two very prominent tubercles on the external surface of the cartilage. It is some- 
 times continued as far as the os hyoides by a small lateral prolongation, and at other 
 times it is continuous with the thyro-hyoid. The sterno-thyroid is interrupted by a ten- 
 dinous intersection analogous to those of the rectus abdominis. It is not uncommon to 
 find the two sterno-thyroid muscles united together by an intervening aponeurosis shaped 
 like the letter V, opening upward, and corresponding to the fourchette of the sternum. 
 
 Relations. — It is covered by the sterno-hyoid and omo-hyoid muscles, and it covers the 
 trachea, the lower part of the subclavian and internal jugular veins, the common carotid 
 artery, and the arteria innominata on the right side, the thyroid body and the thyroid 
 vessels. The middle thyroid vein runs along its inner border, an important relation in 
 regard to the operation of tracheotomy. 
 
 The Thyro-hyoideus. 
 
 This is a small quadrilateral muscle (hyo-thyroideus, Albinus), which may be consider- 
 ed a continuation of the stemo-thjToid (^o,figs. 113 and 114). It arises from the oblique 
 line, and the tubercles of the thyroid cartilage, where it is embraced by the tendinous 
 arch of the preceding muscle, passes vertically upward, and is inserted into the posterioi 
 surface of the body and part of the great cornu of the os hyoides. 
 
 Relations. — It is covered by the two muscles of the superficial layer, and covers the 
 thyroid cartilage, and the th3TO-hyoid membrane. 
 
 Action of the Muscles of the Sub-hyoid Region. — These muscles are the most simple, 
 both in structure and in action : they all concur in depressing the lower jaw ; but if the 
 lower jaw is ficxed, they produce flexion of the head. The fixed points of all are below, 
 viz., at the sternum on the inside, at the clavicle in the middle, and at the scapula on the 
 outside. This arrangement not only bestows particular uses upon each, but renders the 
 common action of all more certain. Thus, the omo-hyoid, at the same time that it de- 
 presses the 03 hyoides, carries it backward and towards its own side. Wliere the two 
 omo-hyoid muscles act together, the os hyoides is directly depressed, and forced back- 
 ward against the vertebral column. The sterno-hyoid and the sterno-thyroid, prolonged by 
 the thyro-hyoid, draw the os hyoides directly downward. The principal use of the thyro- 
 hyoid is, to move the os hyoides upon the thyroid cartilage, in which movements the upper 
 part of the cartilage is carried behind the os hyoides, the curve described by which is al- 
 ways greater than that formed by the cartilage. The muscles of the sub-hyoid region nev- 
 er eissume as their movable point 3 either their sternal, clavicular, or scapular attachments 
 
 ^'P^^^IP^'^F*^ 
 
228 
 
 MYOLOGY. 
 
 MUSCLES OF THE SUPRA-HYOID REGION. 
 
 The Digastricus. — Stylo-hyoideus. — Mylo-hyoideus. — Genio-hyoideus. — Their Action. 
 The muscles of this region, taken in the order of super-imposition, are the digastric, 
 the stylo-hyoid, the mylo-hyoid, and the genio-hyoid. 
 
 The Digastricus. 
 
 Distection. Remove the platysma, reflect the mastoid insertion of the stemo-mastoid ; 
 
 Pig^ 114. detach and raise the sub-maxillary 
 
 and the lower extremity of the pa- 
 rotid gland. 
 
 The digastric muscle (biventer 
 mjixillae inferioris, Albinus,p p,figs. 
 113 and 114), so named because it 
 consists of two fleshy bellies, united 
 by an intermediate tendon, reaches 
 the whole extent of the supra-hyoid 
 region, from behind forward. It is, 
 in some respects, the type of digas- 
 tric muscles. It is curved upon it- 
 self, forming the arc of a circle, with 
 the concavity directed upward. 
 
 It arises from the digastric groove 
 in the mastoid process, and from the 
 anterior edge of that process, in front 
 of the sterno-mastoid ; it it inserted 
 into the side of the symphysis menti, 
 below the sub-mental tubercles, into 
 the whole extent of the digastric fos- 
 sa. It is also attached to the os hy- 
 oides by means of an aponeurotic ex- 
 pansion. 
 
 Its origin from the mastoid pro- 
 cess is partly fleshy and partly ten- 
 dinous, the tendon being prolonged 
 for some distance upon the upper border of the muscle. The fusiform fleshy belly pro- 
 duced in this manner passes forward, inward, and downward, into the interior of a sort 
 of fibrous cone, forming the commencement of the intermediate tendon. This tendon, 
 which is about two inches in length, follows at first the direction of the muscle, almost 
 always perforates the stylo-hyoid muscle, and is then received into a fibrous ring attach- 
 ed to the OS hyoides, and lined by a synovial capsule. This fibrous ring is often wanting. 
 A broad aponeurotic expansion proceeds from the intermediate tendon, and is fixed to the 
 OS hyoides. When this is united to the corresponding structure on the opposite side, 
 they form a very strong, triangular aponeurosis, called the supra-hyoid aponeurosis, which 
 occupies the interval between the two muscles, and serves as a kind of floor for the other 
 muscles of the supra-hyoid region. After having passed through the fibrous ring, the ten- 
 don changes its direction, and is reflected at an obtuse angle upward and forward, to ter- 
 minate in another tendinous cone. From the interior of this cone the fleshy fibres of the 
 anterior belly take their origin. This belly is not so strong as the posterior, and is insert- 
 ed by separate tendons, sometimes intersecting those of the opposite side, into the whole 
 extent of the digastric fossa, below the sub-mental tubercles. Some fibres are often 
 blended with those of the mylo-hyoid. It is not uncommon to see a small fasciculus 
 arising from the os hyoides, and strengthening the anterior belly. The two anterior bel- 
 lies are sometimes united by a raphe, and by a small transverse fibrous bundle. 
 
 Relations. — It is covered by the platysma and sterno-mastoid, the parotid and the sub- 
 maxillary glands, the latter of which it embraces by the concavity of its upper border : it 
 covers the muscles which arise from the styloid process, the mylo-hyoid muscle, the in- 
 ternal jugular vein, the external carotid artery, and its labial and lingual branches, the 
 mternal carotid, and the hypo-glossal nerve, which lies parallel with, and beneath the 
 intermediate tendon of the muscle. 
 
 Its action is very complicated : when the posterior belly contracts alone, the os hyoides 
 is carried backward and upward ; the anterior belly carries it forward, and also upward. 
 When the two bodies of the muscle contract at the same time, these opposite effects are 
 destroyed, and the os hyoides is carried directly upward. In all these motions, the low- 
 er jaw must be fixed. If the os hyoides is fixed, the posterior belly becomes a depressoi 
 of the jaw, on account of the reflection of the muscle ; the anterior and the posterior bel- 
 lies can incline the head backward, but this inclination of the head backward during mas- 
 tication, and when the jaws are separated, depends on the action of the posterior exten- 
 
THE STYLO, MYLO, AND GENIO HYOIDES. 229 
 
 BOr muscles of the neck ; leistly, the anterior belly of the digastric is the tensor of the 
 supra-hyoid fascia. 
 
 The Stylo-hyoideus. 
 
 Dissection. — Detach the posterior belly of the digastric. This is a small and very thin 
 muscle {q,fig. 114 ; ^ q,fig^- ^^'^ ^^^ ^^'^), like all those which are attached to the sty- 
 loid process. 
 
 It arises from the back of the styloid process, at a short distance from the apex, and oppo- 
 site the insertion of the stylo-maxillary ligament. This origin consists of a small tendon, 
 which terminates in a fibrous cone, from the interior of which the fleshy fibres commence. 
 These proceed downward, forward, and inward, and form a bundle, which is almost al- 
 ways perforated by the tendon of the digastric. Occasionally the fibres pass only in front 
 of that tendon. They are iiiserted into the body of the os hyoides, at a short distance 
 from the median line. Sometimes the tendon of insertion is reflected upon itself, and 
 forms the pulley for the digastric. 
 
 Relations. — It is covered by the posterior belly of the digastric, and has the same re- 
 lations as that muscle. It is not uncommon to find a second stylo-hyoid muscle, ex- 
 tending from the styloid process to the little cornu of the os hyoides. This muscle takes 
 the place of the stylo-maxillary ligament ; it was described by Santorini under the name 
 of the stylo-hyoideus iwvus, and was noticed also by Albinus.* 
 
 The Mylo-hyoideus. 
 
 Dissection. — Detach the anterior belly of the digastric at its maxillary insertion ; dis- 
 sect the sub-maxillary gland, and turn it outward. 
 
 This muscle {r, figs. 113 and 114), situated immediately below, i. e., deeper (as re- 
 gards the surface) than the anterior belly of the digastric, is thin and quadrilateral. It 
 arises from the whole extent of the mylo-hyoid line, from opposite the last molar to the 
 symphysis menti, by short aponeurotic fibres. The fleshy fibres arising from these pass 
 in different directions : the internal (or anterior), very short, proceed inward to a median 
 fibrous raphe, which traverses the whole supra-hyoid region ; the external (or posterior) 
 pass much less obliquely to the upper part of the body of the os hyoides. The median 
 raphe is sometimes wanting, and the muscular fibres of the opposite sides are continuous 
 with each other. Some of the fibres are often lost in the digastric, and are even contin- 
 uous with the sterno-hyoid. The two mylo-hyoid muscles may, with great propriety, be 
 regarded as a single muscle, divided by a tendinous intersection in the median line. 
 
 Relations. — It is covered by the anterior belly of the digastric, the supra-hyoid fascia, 
 the platysma, and the sub-maxillary gland ; and it covers the genio-hyoid, the hyo-glos- 
 sus, and stylo-glossus muscles, the lingual and hypo-glossal nerves, the Whartonian 
 duct, the sublingual gland, and the buccal mucous membrane. 
 
 The Genio-hyoideus. 
 
 This muscle {s,fig. 114, 143, 147) is situated below, i. e., deeper than the preceding, 
 which must be divided very carefully, in order to avoid raising the two together. It is a 
 small, round, fleshy bundle, described by anatomists as consisting of two very minute 
 muscles, separated from each other by an extremely delicate cellular tissue. Sometimes 
 it is impossible to separate them; at other times the two bundles are very distinct 
 They arise from the inferior sub-mental tubercle, and proceed downward and backward, 
 to be inserted into the upper part of the os hyoides. 
 
 Relations. — ^They are covered by the mylo-hyoids, and cover the hyo-glossal muscles. 
 
 Actions of the Muscles of the Supra-hyoid Region. 
 
 These are of two kinds, relating to the depression of the lower jaw, and to the eleva- 
 tion of the OS hyoides. 
 
 The OS hyoides being fixed by the muscles of the sub-hyoid region, all the supra-hyoid 
 muscles, with the exception of the stylo-hyoids, depress the lower jaw ; and it should 
 be observed that they are situated in the most favourable manner for this purpose ; for, 
 on the one hand, they are almost perpendicular to the lever, and, on the other, they are 
 attached as far as possible from the fulcrum. The obliquity of their direction has also 
 this advantage, that the lower jaw is carried backward as well as depressed, and thus 
 the orifice of the mouth is greatly increased in size. 
 
 But the most important action of these muscles relates to the elevation of the os hy- 
 oides. This elevation is an indispensable element in the act of deglutition, and also in 
 the protrusion of the tongue. Thus, the os hyoides is carried upward and backward by 
 the stylo-hyoid muscles and by the posterior belly of the digastric, upward and forward 
 by the anterior belly of the digastric and by the mylo- and genio-hyoids, and directly up- 
 ward by the combined action of all these muscles. The base of the tongue, of which 
 the os hyoides constitutes, in some degree, the framework, is associated with it in all 
 
 * Albinus termed it stylo-hyoideus alter. 
 
MYOLOGY. 
 
 these movements, which take place at different periods of deglutition : thus, the move- 
 ment upward and forward is effected during the period when the alimentary mass is 
 driven from the cavity of the mouth into the pharynx, which enlarges for its reception. 
 The direct elevation takes place when the mass is passing, and the movement upward 
 and backward occurs after it has passed, so as to prevent its return into the mouth. 
 When the lower jaw is fixed against the upper, and the os hyoides is also fixed by the 
 sub-hyoid muscles, the muscles of the supra-hyoid region assist in flexing the head. 
 Lastly, the os hyoides is elevated during the production of acute, and depressed during 
 that of grave, vocal tones. 
 
 MUSCLES OF THE CRANIAL REGION. 
 Occipito-froTttalis . — A uricular Muscles . 
 The muscles of the cranial region are the occipito-frontalis and the auricular muscles. 
 
 The Occipito-frontalis. 
 
 Dissection. — Shave the head, and make a horizontal incision above the superciliary 
 arch ; make a second incision in a vertical direction from before backward, and reaching 
 from the former to the superior semicircular line of the occipital bone ; be very careful 
 not to dissect away the epicranial aponeurosis, nor the fibres of the muscle ; commence 
 the dissection at the fleshy fibres, which adhere less intimately to the skin than the 
 aponeurosis. 
 
 The occipito-frontalis (epicranius, Albinus, a' a', jig. 113) is sometimes regarded as one 
 muscle with two bellies ; sometimes as a combination of two separate muscles, the oc- 
 cipital and the frontal. It covers the roof of the scull. We shall describe the occipital and 
 frontal portions only ; the aponeurosis will be elsewhere noticed. (Vide Aponeurology.) 
 
 1. The occipital portion, or occipital muscle, covers a great part of the occipital bone, 
 and is situated over the superior occipital protuberance. It is thin and quadrilateral. 
 It arises from the two external thirds of the superior semicircular line, and from the 
 neighbouring part of the mastoid process of the temporal bone, and is inserted into the 
 posterior border of the cranial aponeurosis, of which it may be regarded as the tensor. 
 The occipital attachment is composed of tendinous fibres, the fleshy fibres proceeding 
 from which pass upward in a parallel direction, and, after a short course, terminate in 
 the aponeurosis. 
 
 2. The frontal portion, or frontal muscle, is placed at the front of the cranium ; it is 
 thin, and irregularly quadrilateral, like the preceding. It is attached above to the cranial 
 aponeurosis, and terminates below in the following manner : 1. The internal or median 
 fibres are prolonged into a fleshy band, which constitutes the pyramidalis nasi ; 2. The 
 fibres next on the outside are continuous with those of another muscle, viz., the levator 
 labii superioris alaeque nasi — ^to the outside of these fibres, the muscle is attached to the 
 internal orbital process ; 3. The greater number of the fibres are blended with those of 
 the orbicularis palpebrarum. The upper border of the muscle, which is attached to the 
 aponeurosis, forms a semicircular line, that, in many individu^^, causes a projection un- 
 der the skin. 
 
 Relations. — Tlie occipito-frontalis covers the roof of the scull ; hence the name of epi- 
 cranius (Albinus). It rests upon the pericranium (the periosteum of the cranial bones), 
 being separated from it by a quantity of moist cellular tissue, which admits of a consid- 
 erable degree of mobility of the integuments, and is so elastic that it returns to its origi- 
 nal situation after being displaced by any movements of the hairy scalp. The super- 
 ficial surface of this muscle is covered by the skin, and is united to it by a very dense, 
 almost fibrous cellular tissue, in which are ramified the numerous vessels and nerves of 
 the cranial integuments. 
 
 Action. — The occipital portion is a tensor of the epicranial aponeurosis, which, when 
 stretched, affords a fixed point for the frontal portion. This latter raises the upper half 
 of the orbicularis palpebrarum, elevates the eyebrows and the skin over the root of the 
 nose, and has a great effect in the expression of emotions of delight. This muscle pro- 
 duces the transverse wrinkles on the forehead, which give to the countenance of indi- 
 viduals who are habitually gay a peculiar expression, that is often imitated by painters. 
 These transverse wrinkles do not extend over the triangular interval, which separates 
 the two fleshy bellies of the muscle in the centre of the forehead. 
 
 The occipito-frontalis must be regarded as an elevator of the upper eyelids ; it is blend- 
 ed with the orbicularis palpebrarum in the same manner as the labial muscles with the 
 orbicularis oris. In this respect the occipito-frontalis is assisted by the levator palpe- 
 hrse superioris, and antagonized by the corrugator supercilii and orbicularis palpebrarum. 
 Can this muscle erect the hairs on the head 1 It is certain that it can move the entire 
 hairy scalp, for many individuals are able to do this at will ; but it appears to me that 
 the expression, the hairs stand on end, as regards man, is merely figurative, and is de- 
 rived from what occurs in the lower animals, in which this erection of the hair is very 
 
THE AURICULAR MUSCLES, ETC. 1281 
 
 manifest. Perhaps, however, the skin itself may produce this effect by the same mech- 
 anism as that which gives rise to goose skin. 
 
 The Auricular Muscles. 
 
 Dissection. — Be very careful in dissecting the superior and anterior auricular muscles, 
 which are extremely thin, and consist only of a few colourless fibres. To render them 
 as tense and prominent as possible, it is necessary to draw the ear away from the mus- 
 cle to De examined. 
 
 All these muscles are rudimentary in man, in whom the external ear is almost im- 
 movable. They may all be considered as dilators of the auditory meatus, to which there 
 is no constrictor or sphincter in the human subject : certain animals, however, possess- 
 ing a very delicate sense of hearing, have constrictor muscles, which draw together and 
 move the different pieces forming the cartilaginous portion of this canal. 
 
 The auricular muscles are three in number : a superior, an anterior, jmd a posterior. 
 
 The Auricularis Superior. 
 
 This muscle, which is extremely thin and of a triangular form (b',Jig. 1 13), oocupies the 
 temporal fossa. It arises from the external border of the epicranial aponeurosis, of which 
 it seems to be a dependance , from this origin its fibres converge, and are inserted into the 
 upper part of the concha. It is covered by the skin, and lies upon the temporal fascia. 
 
 Action. — To raise the ear (attollens auriculam, Albinus). 
 
 The Auricularis Anterior. 
 
 This muscle (c'. Jig. 1 13) is still thinner and less marked than the preceding, with 
 which it is continuous. It is also triangular, and arises from the outer edge of the oc- 
 cipito-frontalis and the cellular tissue covering the zygomatic region ; the fibres con- 
 verge from their origin, and are inserted into the front of the helix. It is covered by the 
 skin, and lies upon the temporal fascia, from which it is separated by the temporal artery 
 and vein. 
 
 Action. — To draw the auricle forward and upward (anterior auriculae, Albinus). 
 
 The Auricularis Posterior. 
 
 This muscle {d',fig. 113) is much more decidely marked than the preceding, and is 
 composed of two or three distinct fleshy fasciculi (tres retrahentes auriculam, Albinus), 
 which extend from the base of the mastoid process, and sometimes also from the occipi- 
 tal bone to the lower part of the concha. 
 
 Action. — To draw the aiu-icle backward. 
 
 MUSCLES OF THE FACE. 
 
 All the muscles of the face are arranged in groups around its several openings, and 
 may be classed either as dilators or constrictors. The nostrils alone have no constrictors. 
 
 The eyelids must be opened and closed entire, without the production of any folds ; 
 the nostrils must remain constantly open, for the skin around these orifices has within it 
 a corresponding lamina of cartilage, which gives it the necessary tension, strength, and 
 elasticity, and into which the muscles are inserted. There is no such arrangement at 
 the orifice of the mouth, the muscles being there inserted into other muscles. 
 
 From the three openings around which the muscles of the face are grouped, these may 
 be arranged into three distinct regions, viz., the palpebral, the nasal, and the buccal. 
 
 MCSCLES OF THE PALPEBRAL ReGION. 
 
 Orbicularis Palpebrarum. — Super ciliaris. — Levator Palpebra Superioris. 
 The muscles of the eyelids are divided into constrictors and dilators. There is one 
 constrictor, viz., the orbicularis palpebrarum, to which the corrugator supercilii is an ac- 
 cessory ; there is also one elevator, viz., the levator palpebrae superioris. 
 
 The Orbicularis Palpebrarum. 
 
 Dissection. — ^Make an elliptical incision through the skin round the base of the orbit ; 
 dissect successively the upper and lower half of the muscle, proceeding from the adhe- 
 rent towards the free border of each eyelid. It is of more importance here than in any 
 other situation to dissect the skin parallel to the fleshy fibres. When the external sur- 
 face of the muscle has been studied, detach it carefully from the subjacent parts, and re- 
 flect it inward. 
 
 The orbicularis palpebrarum {e',fig. 113) forms an elliptical zone of variable size round 
 the eyelids, and also an extremely thin layer upon them. It is a sphincter, and, like all 
 muscles of this kind, is composed of circular fibres ; but, as a special exception, it is also 
 provided with a remarkable tendon of origin, named the straight tendon of the orbicularis ; 
 this is about two hues in length and half a line in breadth, arises from the ascending pro- 
 cess of the superior maxilla, anteriorly to the lachrymal groove, and passes in front of 
 
2JK5 MYOLOGY. 
 
 the lachrymal sac, where it divides into two unequal parts, an upper and smaller, and a 
 lower more capacious ; sometimes it corresponds entirely to the upper part of the sac. 
 At first it is flattened from before backward, but is then twisted upon itself, so as to pre- 
 sent one surface upward and another downward. Opposite the inner angle of the eye- 
 lids, this tendon, which is also called the palpebral ligament, becomes bifurcated, and 
 each division is attached to the inner end of the corresponding tarsal cartilage ; from the 
 posterior surface of the tendon a very strong aponeurotic lamina is given off, and forms 
 the outer wall of the lachrymal sac : this is the reflected tendon of the orbicularis palpebra- 
 rum. Fleshy fibres proceed from the anterior and posterior surfaces, and from the bor- 
 ders of the straight tendon, and also from the anterior border of the reflected tendon ; 
 but the greater number arise by well-marked tendinous prolongations from the external 
 orbital process of the frontal bone, from the ascending process of the superior maxilla, 
 and from the internal and lower third of the base of the orbit. From these origins the 
 fleshy fibres pass outward, dividing into two halves, an upper, which describes concen- 
 tric curves with the concavity directed downward, and a lower, also describing concen- 
 tric curves, but with the concavity directed upward (duo palpebrarum musculi, Vcsalius). 
 Each of these halves is subdivided into two sets of fibres : an external set, surrounding 
 the base of the orbit ; and an internal or palpebral, belonging to each eyelid : hence the 
 distinction drawn by Riolanus between the orbicularis and the ciliaris or palpebralis mus- 
 cles. The external fibres (forming the orbicular portion) describe a complete ellipse. I 
 have never met with the fibrous intersection at the outer part of the eye, mentioned by 
 some anatomists. The palpebral or ciliary fibres, forming the proper palpebral portion, 
 arise from the bifurcation of the tendon, and describe concentric arcs, which are united 
 on the outside at an acute angle to a cellular raphe. 
 
 Relations. — The orbicular portion is closely united to the skin by means of a fibrous 
 and adipose tissue, which is very compact over the upper, and loose over the lower por- 
 tion of the muscle ; it is connected with the skin of the eyelids by a serous cellular tis- 
 sue, remarkably susceptible of infiltration. It covers the lachrymal sac, the corrugator 
 supercilii muscle, the orbited arch, the maxillary bone, the temporal muscle, and the su- 
 perior attachments of the zygomaticus major, of the levator labii superioris alaeque nasi, 
 and of the levator labii superioris. 
 
 It is separated from the conjunctiva by a fibrous membrane and the tarsal cartilages. 
 Its circumference is blended with the pyramidalis nasi on the inside, with the occipito- 
 frontalis and corrugator above, but is free below ; occasionally it gives off a few fibres 
 from its outer border, some of which form the zygomaticus minor, and others of a pailer 
 colour terminate in the skin. 
 
 Actions. — ^The orbicularis acts in the same manner as £ill other sphincters, that is to 
 say, the circular fibres of which it is composed contract towards the centre ; but, as the 
 fleshy fibres have their fixed point at the straight tendon, and still more at the internal 
 insertions, it follows that, during the contraction of this muscle, it is thrown in some 
 measure inward, and by it the integuments of the forehead, the temple, and the cheek 
 are drawn towards the inner angle of the eye. The intimate adhesion between the skin 
 and the upper half of the muscle explains why, during its contraction, that part is ren- 
 dered more apparent beneath the skin than the lower. The palpebral portion contracts 
 independently of the orbicular, a fact that confirms the distinction made by Riolanus. 
 Nor is this all : the contraction of this palpebral portion, or palpebralis muscle, properly so 
 called, is habitually involuntary, while the contraction of the orbicular portion is subject 
 to the will. The palpebral fibres are pale, and resemble the muscular fibres of the ali- 
 mentary organs ;* the orbicular fibres are red, like those of the muscles of animal life. 
 When the palpebral fibres contract, they do not produce the occlusion of the eye, by a 
 concentric approximation of the fibres, but by bringing together the free edges of the eye- 
 lids, the only method permitted by the tarsal cartilages. The curve described by the 
 rnuscular fibres of the lower being smaller than that formed by those of the upper eye- 
 lid, it follows that the closing of the eyes depends principally upon the latter. 
 
 The Super ciliaris. 
 
 Dissection. — Make a vertical incision in the median line between the frontal muscles ; 
 ttim back carefully the frontal and the orbicularis muscles from within outward. 
 
 The superciliaris (corrugator supercilii, Albinus, a', Jig. 114) is a narrow and tolerably 
 thick fasciculus, generally of a deeper red than the orbicularis, and situated along the 
 superciliary arch, with the direction of which it corresponds. It arises by one, often by 
 two or three portions, from the internal portion of this arch ; proceeds upward and out- 
 ward, describing a slight curve, having its concavity downward, and is blended with the 
 orbicularis palpebrarum at about the middle of the arch of the orbit. From this arrange- 
 ment, Albinus described it as a root of the orbicularis. According to some authors, it 
 terminates in the skin of the eyebrow (cutaneo-surcilier, Dumas) ; but I have always 
 found it attached to the deep layer of the orbicularis muscle. 
 
 * See note *, p. 238. 
 
THE LEVATOR PALPEBE^ SUPERIORIS, ETC. 2SSt 
 
 Relations. — It is covered by the pjrramidalis nasi, the orbicularis palpebrarum, and the 
 occipito-frontalis, and it covers the os frontis, the supra-orbital and frontal arteries, and 
 the frontal branch of tlie ophthalmic nerve. 
 
 Action. — This muscle corrugates the eyebrow, and dravrs it downward and inward. It 
 is, therefore, regarded as the principal agent in the expression of grief The repeated 
 contraction of these muscles in irascible individuals gives a character of severity to the 
 countenance, from the constant approximation of the eyebrows, and the permanence of 
 the vertical wrinkles formed between them. 
 
 The Levator Palpebrce Supreioris. 
 
 Dissection. — Remove the roof of the orbit by two cuts with a saw, meeting at an acute 
 angle opposite the foramen opticum ; detach the bone with care, so as to leave the peri- 
 osteum untouched ; cut the periosteum from before backward, and separate the frontal 
 nerve which passes above and parallel to the muscle, which may then be separated care- 
 fully from the superior rectus muscle of the eye. 
 
 The levator palpebro'. superioris (see description of the eyelids) is an elongated, flat, 
 triangular, and very thin muscle, placed in the orbital cavity, directed horizontally from 
 behind forward, and curved at its anterior extremity, sa as to form a concavity directed 
 downward. It arises from the inferior surface of the lesser wing of the sphenoid, im- 
 mediately above the optic foramen, and from the sheath of the optic nerve, and is insert- 
 ed into the upper border of the tarsal cartilage. Its sphenoidal origin consists of a small 
 tendon, and its attachment to the sheath of the optic nerve is a fibrous ring common to 
 aU the muscles of the eye. From these points the fleshy fibres proceed forward, form- 
 ing a broad, thin bundle, increasing in width and diminishing in thickness towards its 
 tarsal insertion, which is effected by means of a broad aponeurosis. 
 
 Relations. — Covered by the periosteum of the orbit, from which it is separated by the 
 frontal branch of the ophthalmic nerve ; covered, also, by some adipose tissue and by the 
 fibrous membrane of the upper eyelid, it covers the superior rectus of the eye and the 
 conjunctiva. 
 
 Action. — It raises the upper eyelid. Its reflection over the globe of the eye explains 
 that peculiar motion of the eyelid by which its upper edge is buried below the orbital 
 arch. The relaxation of this muscle suffices for the depression of the upper eyelid in 
 passive closure of the eyes, while the active occlusion depends on the contraction of the 
 orbicularis. 
 
 There is no analogous muscle for the lower eyelid, which scarcely concurs either in 
 opening or shutting the eyes. 
 
 NASAL REGION. 
 
 The Pyramidalis Nasi. — Levator Labii Superioris Alceque Nasi. — Tranaver salts, or Trian- 
 gularis Nasi. — Depressor Ala. Nasi. — Naso-labialis. 
 The muscles of this region are the pyramidalis nasi, the levator labii superioris alae- 
 que nasi, the transversalis or triangularis nasi, the depressor alae nasi, or myrtiformis, 
 and the naso-labialis of Albinus. 
 
 The Pyramidalis Jfasi. 
 
 Dissection. — ^Trace doiwn upon the dorsum of the nose the internal fibres of the occip- 
 ito-frontalis, directing the scalpel parallel to these fibres, which have a vertical course. 
 
 The pyramidalis nasi (/, fig. 113) is a prolongation of the internal fibres of the occipito- 
 frontalis, of which it may be regarded as a prolongation (frontahs pars per dorsum nasi 
 ducta, Eustachius). It lies upon the bridge of the nose on each side of the median line. 
 It is separated from the muscle of the opposite side by a thin layer of cellular tissue. It 
 is narrower at its origin than at its termination, which takes place in the aponeurosis of 
 the transverse muscle of the nose. 
 
 Relations. — It is covered by the skin, to which it closely adheres, especially below, and 
 it covers the nasal bones and lateral cartilages. 
 
 Action. — This small muscle has been regarded as an elevator of the ala. and, conse- 
 quently, a dilator of the nose ; but I believe it rather acts in depressing the inner angle 
 of the eyebrow, and the skin between the eyebrows. In this respect it has considerable 
 influence upon the expression of the countenance. 
 
 The Levator Labii Superioris AlcRque JSTasi. 
 Dissection. — Make a vertical or somewhat oblique incision from the ascending process 
 of the superior maxilla to the upper lip. Reflect outward the inner and lower part of the 
 orbicularis muscle. 
 
 This muscle (^, fig. 113) is thin, triangular, and divided into two portions below. It 
 extends from the ascending process of the superior maxilla to the ala of the nose and the 
 ^upper lip. It arises by a narrow extremity from the internal orbital process of the frontal 
 bone, immediately below the tendon of the orbicularis palpebrarum, passes obliquely 
 
 Go 
 
234 T ,? >7, MYOLOGY. 
 
 downward and outward, becomes much broader, and is inserted partly into the cartilage 
 of the ala of the nose, or, rather, into the very dense skin which covers it, and partly into 
 the orbicularis oris, or, rather, into the skin of the upper lip. The cutaneous portion of 
 this muscle is distinguished by its paleness, compared with the red colour of the rest. 
 
 Relations. — It is covered by the skin, and a small portion of the orbicularis palpebrarum ; 
 and it covers the ascending process of the superior maxilla, and the transverse muscle of 
 the nose. 
 
 Action. — It elevates both the ala of the nose and the upper lip. I consider it the most 
 important of all the muscles of the nose, because the elevation of the alae dilates the nos- 
 trils, and thus aids most essentially in cases of impeded respiration. It is a respiratory 
 muscle of the face, and has, also, great influence over the countenance, producing the 
 expression of contempt. Its action upon the upper lip is of much less importance than 
 that upon the nose. 
 
 The Transversalis, or Triangularis JVasi. 
 
 Dissection. — Remove with great care the skin covering the ala of the nose, and then fol- 
 low this muscle below the inner edge of the common elevator ; or, what is better, remove 
 all the soft parts covering the ala of the nose, and dissect the muscle from its deep surface. 
 
 The transversalis vusi (compressor narium, h',figs. 113, 114), which I regard as a de- 
 pendance of the muscle next to be described, is a small and very thin triangular muscle, 
 stretching from the inner part of the canine fossa to the bridge of the nose. It arises by 
 a narrow extremity from the canine fossa, passes forward, enlarging as it proceeds along 
 the ala of the nose, and terminates by a very thin aponeurosis, which is blended in the 
 median line with that of the opposite side, and with the pyramidalis. It is covered by 
 the skin, to which it closely adheres, and by the common elevator ; and it covers the car- 
 tilage of the ala, and a small part of the superior lateral cartilage of the nose. 
 
 Action. — The action of this small muscle is not yet weU determined. Some have 
 agreed with Riolanus in considering it a dilator (qui alam naris diktat sine elevatione 
 nasi, Riolanus) ; others think, with Spigelius and Albinus, that it is a constrictor of the 
 nose (primi paris constringentium alas, Spigelius ; compressor naris, Albinus). It is prob- 
 able that its action varies according to the shape of the ala : if this be concave outward, 
 it is a dilator ; if convex outward, it is a constrictor. Its action is very slight. 
 
 The Depressor Alee JVasi, or Myrtiformis. 
 
 Dissection. — Evert the upper lip, and remove the mucous membrane on each side of 
 the fraenum. The two myrtiformes may then be separated by a vertical incision in the 
 median line. It will be apparent that the myrtiformis and transversalis form only one 
 muscle, which arises from the alveolar border near the lateral incisor, the canine and the 
 anterior bicuspid teeth, and is distributed to the orbicularis oris, the alae, and the septum 
 of the nose. 
 
 This muscle {if, fig- 114) is short and radiated, and arises by a narrow extremity from 
 the incisive or myrtiform fossa of the superior maxilla, opposite the canine and two in- 
 cisor teeth (incisif moyen, Winslow). Its fibres diverge upward and outward, and are in- 
 serted thus : the lower, or descending, behind and in the substance of the orbicularis oris ; 
 and the upper or ascending, into the ala and septum of the nose. Its upper border is 
 not distinct from the lower border of the transversalis. Chaussier, on account of its 
 termination in the upper lip, regarded it as one of the origins of the orbicularis oris. 
 
 Relations. — It is covered by the buccal mucous membrane, by the orbicularis oris, and 
 the common elevator, and it lies upon the maxillary bone. It is continuous, without any 
 line of demarcation with the transversalis nasi. The inner border of the muscle of one 
 side is separated from that of the other by an interval, corresponding to the fraenum of 
 the upper lip. 
 
 Action. — It depresses the ala of the nose, and has also been considered a depressor of 
 the upper lip (depressor labii superioris,* Cowper). I regard it rather as an elevator of 
 that lip. 
 
 The J^aso-labialis of Albinus. 
 This consists of a fasciculus which it is difficult to demonstrate in many subjects. It 
 arises from the anterior extremity of the septum of the nose, passes horizontally back 
 ward, is then reflected downward, and terminates like the preceding in the orbicularis, 
 of which it may be considered a root. 
 
 MUSCLES OF THE LABIAL REGION. 
 rhe Orbicularis Oris. — Buccinator. — Levator Labii Superioris. — Caninus. — Zygomatict, 
 Major et Minor. — Triangularis. — Quadratus Menti. — Levator Labii Superioris. — Move- 
 ments of the Lips and those of the Face. 
 
 No region has so many muscles as the orifice of the mouth : seventeen, nineteen, and 
 * Depressor labii superioris aliBque nasi of other writers. 
 
THE ORBICULARIS ORIS AND THE BUCCINATOR. 4)85 
 
 often twenty-one muscles, are grouped round it, viz., the orbicularis oris, the common 
 elevators of the alae and lip already described, the proper elevators of the lip, the great zy- 
 gomatics, the canine, the buccinators, the triangulares,the quadrati or the levatores menti ; 
 and often two muscles on each side, viz., the risorius of Santorini, and the small zygomatic. 
 
 The Orbicularis Oris. 
 
 Dissection. — Make an elliptical incision round the opening of the mouth, and dissect 
 back the skin with great care, the mouth being previously distended by the introduction 
 of tow between the lips and alveolar borders. 
 
 The orbicularis oris (J,' I', figs. 113 and 114) is the sphincter of the orifice of the mouth ; 
 it is essentially the constituent muscle of the lips, occupying the entire space betweeii 
 the free edge of the upper lip and the nose, and the free edge of the lower lip and the 
 transverse furrow above the chin. 
 
 We shall consider, with Winslow, the orbicularis to be composed of two halves, each 
 constituted by a demi-zone, of semi-elliptical concentric fibres, terminating on either side 
 at the commissures of the lips. These fibres, which are all fleshy, do not become con- 
 tinuous opposite the commissures of the lips, but only intersect each other, those of the 
 upper half being continuous with the lower fibres of the buccinator, and those of the low- 
 er half with the upper fibres of the same muscle. 
 
 The thickness of the two halves varies in different individuals, particularly around the 
 free borders of the lips, where the fasciculi of the muscle are somewhat everted. In 
 the negro this is very remarkable. The thickness of the lips depending upon this cir- 
 cumstance must be distinguished from that which is the effect of a scrofulous habit. 
 
 Relations. — These muscles are covered by the skin, to which they adhere intimately, 
 and hence the facility of bringing together the entire depth of the surface of wounds in 
 the lips, by retentive applications to the skin only. They cover the mucous membrane 
 but are separated from it by the labial glands, the coronary vessels, and a great number 
 of nervous filaments. Their outer circumference receives all the extrinsic muscles of 
 the lips, which terminate in these as in a conmion centre. Their inner circumference 
 circumscribes the opening of the mouth. The differences in the dimensions of this open- 
 ing occasion the varieties observed in the size of the mouth, but the capacity of the buc- 
 cal cavity is in no way influenced by these variations. 
 
 Actions. — These are exceedingly various, and may be studied as connected with the 
 closing of the mouth, with the prehension of aliments by suction, with the playing upon 
 wind instruments, and with the expression of the countenance. I shall here only notice 
 the shutting of the mouth. 
 
 This may be accomplished simply by the approximation of the jaws, which is followed 
 by a corresponding motion of the lips. In active occlusion, or that dependant on the 
 orbicularis, two things may happen : either the lips may be closely drawn against the 
 teeth, and their free edges applied to each other, or they may be pushed forward and 
 puckered ; in the latter case, the buccal opening, which is usually represented by a trans- 
 verse line, resembles a circular, or, rather, a lozenge-shaped orifice. 
 
 The Buccinator. 
 
 Dissection. — Distend the cheeks by stuffing the mouth with tow ; make a transverse 
 incision through the skin, from the commissure of the lips to the masseter muscle, and 
 dissect back the flaps': in order to gain a good view of the posterior border of the mus- 
 cle, turn downward the zygomatic arch and the masseter, and then divide with the saw 
 the inferior maxilla in front of the ramus. 
 
 The buccinator (fig. 113, and b,figs. 114 and 147) is the proper muscle of the cheek; 
 it is broad, thin, and irregularly quadrilateral. It is attached above to the external sur- 
 face of the superior alveolar arch, along the space between the first great molar and the 
 tuberosity of the maxilla ; below, to the external surface of the inferior alveolar arch, 
 or, rather, to that part of the external oblique line of the lower jaw which corresponds 
 with the last two great molars ; and behind, to an aponeurosis existing between this 
 muscle and the superior constrictor of the pharynx (see fig. 147). This aponeurosis, to 
 which the name of buccinato-pharyngeal has been given {ptery go-maxillary ligament), ex- 
 tends from the apex of the internal pterygoid process to the posterior extremity of the 
 internal oblique line of the lower jaw. From these different origins the fleshy fibres 
 proceed forward, the upper somewhat obliquely downward, the lower obliquely upward, 
 and the middle fibres horizontally. In consequence of this arrangement, the fibres inter- 
 sect each other opposite the commissure of the lips, from which points the lower fibres 
 of the muscle proceed to terminate in the upper half of the orbicularis, while the upper 
 fibres end in the lower half of the same muscle. 
 
 Relations. — It is situated deeply behind, where it is covered by the ramus of the lower 
 jaw, the masseter, and a small part of the temporal muscle ; from all these parts, how- 
 ever, it is separated by a considerable quantity of adipose tissue, and by a mass of fat 
 
 which exists even in the most emaciated individuals. More anteriorly it is covered by 
 
 ■-■■'•.■"■~,Trrr"''" " 
 
236 MYOLOGY. 
 
 the zygomaticus major and the zygomaticus minor, and the risonus jf Santorini, where 
 the two latter exist ; and at the commissure it is covered by the canine muscle {levator 
 angnli oris) and the triangularis. The Stenonian duct runs along this muscle before 
 passing through it ; the buccal nerves and the branches of the transverse facial artery 
 lie parallel to its fibres; the external maxillary (i. e., the facial) artery and vein pass 
 perpenaicularly across it, near the commissure. A peculiar aponeurosis, called the buc- 
 cal fascia, is closely united to it, and intervenes between it and all these parts. It cov- 
 ers the mucous membrane of the cheek, from which it is separated by a dense layer of 
 the buccal mucous glands. 
 
 Action. — It is the most direct antagonist of the orbicularis. When the cheeks are not 
 distended, its contraction elongates the opening of the mouth transversely, and, conse- 
 quently, renders the hps tense, and produces a vertical fold upon the skin of the cheek. 
 This fold becomes permanent in the aged, and constitutes one of their most prominent 
 wrinkles. 
 
 When the cheeks are distended by air, or any other substance, the buccinator becomes 
 curved instead of flat, and acquires all the properties of the former class of nmscles. 
 Thus the first effect of its contraction is, that its fibres become straight, or have a ten- 
 dency to become so ; gaseous, liquid, or solid bodies, are then expelled from the mouth, 
 rapidly if the orbicularis offer no obstacle, and gradually should that muscle contract. 
 The buccinator, therefore, fulfils an important ofiice in performances upon wind instru- 
 ments, and hence its name {buccinare, to sound the trumpet). la mastication it is of no 
 less importance, since it pushes the food between the teeth, and expels it from the sort 
 of groove existing between the cheeks and the alveolar arches. 
 
 The Levator Labii Superioris. 
 
 Dissection. — Reflect the lower half of the orbicularis palpebrarum upward, and dissect 
 with care the lower extremity of the muscle about to be described, which adheres close- 
 ly to the skin. It can be best studied from the inner surface. 
 
 This muscle (c', fig. 1 14) is thin and quadrilateral. It is situated upon the same plane 
 as the common elevator, of which it appears to be a continuation, and extends from the 
 base of the orbit to the skin of the upper lip. 
 
 It arises from the inner half of the lower edge of the base of the orbit, on the outei 
 side of the common elevator : from this origin, which is sometimes bifid, the fibres con- 
 verge dovraward and inward, and are inserted successively into the skin, probably into 
 the bulbs of the hairs, as in animals which have mustaches ; so that this muscle would 
 deserve the name of mustachie, which is given by some anatomists to the naso-labial of 
 Albinus. 
 
 Relations. — Its two upper thirds are deeply seated ; its lower third adheres closely to 
 the skin. It is worthy of notice, that almost all the muscles of the face are deeply 
 seated at one of their extremities, and terminate by the other in the skin. It is covered 
 by the orbicularis palpebrarum and the skin, and it covers the infra-orbital vessels and 
 nerves, as they escape from the infra-orbital canal. It is also in relation with the ca- 
 nine muscle, from which it is separated by a quantity of adipose tissue, with the trans- 
 versalis nasi, and with the orbicularis oris, being interposed between the latter muscle 
 and the skin. 
 
 Action. — It raises the upper lip, and draws it a little outward. 
 
 The Caninus. 
 
 Dissection. — Merely reflect the levator labii superioris. 
 
 The canine muscle (levator anguli oris, Albinus, d,fig. 114), so named from its origin, 
 arises from the canine fossa by a broad attachment, from which it proceeds downward 
 and a little outward, diminishing in size, and becoming gradually more superficial, to 
 the commissure of the lips, where it terminates by uniting with the zygomaticus major, 
 and becoming continuous with the triangularis oris. We often find some accessory 
 fibres arising from this muscle, and attached to the skin opposite the commissure. 
 
 Relations. — Above, it is concealed by the levator labii superioris and the infra-orbitary 
 vessels and nerves ; below, it is quite superficial, being only covered by the skin. It 
 covers the superior maxilla, the buccinator, and the buccal mucous membrane. 
 
 Action. — It raises the angle of the mouth, and, from its oblique position, draws it inward. 
 
 The Zygomatici Major et Minor. 
 
 Dissection. — Make an oblique incision from the malar bone to the commissure of the 
 lip, and remove carefully, from the great zygomatic, the fatty tissue which surrounds it. 
 
 The Zygomaticus Major. 
 
 This muscle {m',fig. 113) is a cylindrical, fleshy fasciculus, extending from the malar 
 
 bone to the conunissure of the hp. It arises, by tendinous fibres, from the entire length 
 
 of a horizontal furrow, situated above the lower edge of the malar bone. The fleshy 
 
 fibres approach each other so as to form a fasciculus, which passes obliquely downward 
 
THE TRIANGULARIS, ETC. 237 
 
 and inward towards the commissure, where it is closely united to the canine muscle, 
 and, like it, is continuous with the triangularis or depressor anguli oris. 
 
 Relations. — It is covered by the skin, from which it is separated above by the orbicu- 
 laris palpebrarum, and below by a large quantity of adipose tissue ; it covers the malar 
 bone, the masseter and buccinator muscles, a great collection of fat, and the labial vein. 
 
 Action. — It draws the angle of the mouth upward and outward ; by carrying the com- 
 missure upward, it assists the canine muscle, but in drawing it outward, it antagonizes the 
 same. When the zygomatic and canine contract together, the commissure is drawn di- 
 rectly upward. 
 
 The Zygomaticus Minor. • 
 
 This small muscle {n',fig. 113), which is often wanting, maybe regarded as a depend- 
 ance of the proper elevator of the upper lip. It arises from the malar bone, above the 
 great zygomatic, passes downward and inward to the outer border of the levator labii su- 
 perioris, with which it is blended. It is not uncommon to find this muscle enlarged by 
 fasciculi given off from the outer and lower circumference of the orbicularis muscle of 
 the eyelids. It is covered by the skin and the orbicularis palpebrarum ; and it covers 
 the canine muscle and the labial vein. 
 
 Action. — It assists the common elevator in raising the upper lip and drawing it some- 
 what outward. 
 
 The Triangularis, or Depressor Anguli Oris. 
 
 Dissection. — Make a vertical incision of the skin, from the commissure of the lips to the 
 base of the jaw ; then follow the course of the muscidar fibres as they are successively 
 exposed. 
 
 This muscle {o',fig. 113) is of a triangular shape, as its name implies, and belongs to 
 the inferior maxillary region. It arises, by a broad base within, from the lower border of 
 the inferior maxilla on the side of the median line, and sometimes from the median line 
 itself; and without, from the external oblique line : from these points the fibres pass in 
 different directions, the external almost vertically upward, the internal obliquely upward 
 and outward (the obliquity increasing as we proceed inward), and describing a curve with 
 the concavity looking inward. All these fibres are concentrated into a narrow and thick 
 fasciculus, which terminates at the commissure, on a plane anterior to the fibres of the 
 buccinator and the orbicular oris, being evidently continuous with the canine and the 
 great zygomatic. 
 
 Relations. — It is covered by the skin, beneath which it is clearly discernible, and it cov- 
 ers the quadratus menti, the platysma, and the buccinator. Some colourless fibres, which 
 intersect those of the quadratus at a right angle, and, moreover, follow the same direc- 
 tion as those of the triangularis, may be regarded as a dependance of that muscle, to the 
 inside of which they are situated. They terminate in the skin, like those of the quadratus. 
 
 Action. — It depresses the angle of the mouth, thus antagonizing the canine muscle and 
 the great zygomatic, with which it is continuous. The continuity of these muscles is so 
 manifest, that they may be regarded as constituting a single muscle, broad and triangu- 
 lar below ; bifid above, to form the canine and zygomatic ; and narrow in the middle, 
 where it corresponds to the commissure. The internal fibres of the triangularis, from 
 their oblique direction, are directly opposed to those of the canine muscle ; but its exter- 
 nal fibres have not a similar relation to those of the zygomaticus major. 
 
 The Quadratus Menti, or Depressor Labii Inferioris. 
 
 Dissection. — Dissect back the skin covering this muscle, cutting obliquely downward 
 and outward. 
 
 The quadratus menti {-p'tfig. 113 ; q',fig. 114), situated to the inside of the preceding, is 
 of a square, or, rather, lozenge shape. It arises from the external oblique line of the low- 
 er jaw, and is in a great measure continuous with the platysma, the fibres of wliich pass 
 behind, and sometimes through the triangularis. From this origin it proceeds obliquely 
 upward and inward, therefore in an opposite direction to the triangularis, and is inserted 
 into the skin of the lower lip, on a plane anterior to the corresponding half of the orbicu- 
 laris oris. It is closely united to the skin, and covers the lower jaw, the mental nerve 
 and vessels, the lower half of the orbicularis oris, and the muscle next to be described, 
 with which it is intimately connected. It is separated from the muscle of the opposite 
 side by the prominence of the chin below, but is blended with it above. 
 
 Action. — It depresses the lower lip : from the obliquity of this muscle, it also draws out- 
 ward and downward each half of the lower lip, which is therefore stretched transversely. 
 
 The Levator Labii Inferioris. 
 Dissection. — Evert the lower lip ; divide the mucous membrane at its reflection upon 
 the lip from the lower jaw, so as to expose the origin of the muscle. In order to show 
 its cutaneous insertion, carefully dissect off the skin covering the chin. As the muscles 
 of each side are blended in the median line, it is necessary to make a vertical incision 
 from before backward, opposite the symphysis, in order to separate them. 
 
2^ MYOLOGY. 
 
 This muscle (levator menti, Alb., r',Jig. 114) is a small conoid fasciculus, which forma, 
 in a great measure, the prominence of the chin. It arises from the facette on the side of 
 the symphysis menti, opposite the incisor teeth, whence the name incisif inferieur, Wins- 
 low, which is also given to this muscle. From this point the fibres expand like a tuft, 
 downward and forward, to be inserted into the skin. It is red and fasciculated at its or- 
 igin above, but pale, intermixed with fat, and not fasciculated below, where it is blended 
 on the inside with the opposite muscle, and on the outside with the quadratus menti. 
 Its upper fibres form a concavity above, which partially embraces the great circumfer- 
 ence of the lower half of the orbicularis oris. 
 
 Action. — It raises and wrinktes the skin of the chin, and, consequently, raises the low- 
 er lip, and projects it forward. It appears somewhat singular at first that an elevator of 
 the lip should be situated below it. 
 
 General Considerations regai-ding the Movements of the Lips, and those of the 
 
 Face in general. 
 
 If we take a general view of the muscles of the face, we shall observe, 1. That no re- 
 gion is provided with so great a number of muscles ; 2. That all these muscles are at- 
 tached to a bone by one extremity, while the other is implanted into the skin, or into 
 other muscles ; 3. That the cutaneous portion of these muscles is colourless and non- 
 fjisciculated, presenting all the characteristics of involuntary muscles ;* 4. That those 
 portions which are attached either to the bone or to other muscles have, on the contrary, 
 aH the characters of the voluntary muscles. 
 
 All these muscles are arranged around the several openings of the face, and, conse- 
 quently, they are either constrictors or dilators ; the orifice of the mouth, however, is 
 peculiar! in having the greater number of the muscles of the face specially intended for 
 it. Indeed, the orbicularis oris, or sphincter of the mouth, is antagonized by the bucci- 
 nators or transverse dilators ; by the proper elevators of the upper lip, and the common 
 elevators of that and the alae of the nose ; by the depressors of the lower lip, or quadrati ; 
 by the elevators of the angle of the mouth, viz., the canine muscles, the zygomatici ma- 
 jores, and, where they exist, the zygomatici minores, and the two risorii of Santorini ; 
 and, lEistly, by the depressors of the commissure, or triangulares oris. 
 
 The lips fulfil a great number of uses, all requiring a considerable degree of mobility. • 
 They serve for the prehension of aliments, for suction, and for the articulation of soundsj *' 
 whence the name labial given to consonants specially produced by the action of the lips, ' 
 as b, p, m : they modify the state of the expired air so as to produce in it vibrations of a 
 peculiar character, constituting the act of whistling ; and, in this respect, they illustrate 
 the mechanism of the glottis : they assist in mastication, by retaining the food and con- 
 stantly forcing it between the teeth : they are also employed, during performances upon 
 wind instruments, in regulating the volume of the column of air which strikes upon the 
 body to be thrown into vibrations. The mechanism of their action varies according to 
 the kind of instrument : sometimes, for example, they assist in graduating the rapidity 
 of the column of air, by influencing the orifice through which it issues, as occurs in play- 
 ing upon the flute ; and sometimes they represent vibrating cords situated at the mouth 
 of an instrument, and determining the different tones by their various degrees of ten- 
 sion. In this case, the lips themselves become the vibrating bodies, and propagate their 
 oscillations to other bodies with which they are in contact, independently of the effect 
 produced in the instrument from the passage of a column of air. Examples of this are 
 observed in playing on the horn, trumpet, &c. 
 
 If we examine the muscles of the face in connexion with their influence in producing 
 emotional expressions, we shall find that they are often almost completely removed from 
 the influence of the will, as, for example, where those emotions are not simulated ; but 
 that sometimes, on the contrary, their contraction is altogether voluntary, as in those 
 individuals who, either by profession or habit, are accustomed to imitate feelings which 
 they do not really experience. Nevertheless, it should be remarked that, although the 
 outward expression of every passion may be produced at will upon the face, yet there is 
 always a great difference between the natural emotion and the fictitious representation. 
 
 On the whole, the general expressions of the countenance may be regarded as varie- 
 ties of two great types, viz., those of the cheerful and those of the melancholy emotions. 
 
 * This similarity is limited, however, to the colour and general aspect of the two kinds of muscles ; for 
 even the palest muscular fasciculi of the face are found to consist of striated fibres, precisely similar to those 
 of the other voluntary muscles ; but the fasciculi into which they are collected are neither so evident nor so large.- 
 
 t Man greatly exceeds all animals in the number of muscles attached to his lips. The ape, which is ni'"^ 
 markable for the great mobility of its physiognomy, has, properly speaking, only one muscle for the entire face, 
 which is a dependance of the platysma (or cutaneous muscle) ; therefore, the play of its countenance is con- 
 fined to a grimace, which is always the same, only differing in intensity, and which does not permit it to ex 
 press different and even opposite passions, such as are often depicted upon the human countenance.* 
 
 * £The platysma myoides in monkeys is certainly extended, as a single muscle, over the entire cheek, and 
 forms a muscular layer, covering the lateral pouches appended to the mouth in some of that tribe of animals. 
 In addition to this, however, monkeys have precisely the same number of muscles attached to their lips as in 
 the human subject : they possess, indeed, all the facial muscles found in man ; and, like him, they appear to 
 be capal)le of expressing, by changes in their features, a variety of internal emotions.] 
 
THE MASSETER. 239 
 
 The cheerful emotions are expressed by the expansion of the features, i. e., their retrac- 
 tion from the median line, a movement that is due to the occipito-frontalis, the levatores 
 palpebrarum, and especially to the great zygomatic muscles. The melancholy passions, 
 on the contrary, are expressed by the approach or concentration of the features towards 
 the median line, which is chiefly effected on either side of the face by the corrugator 
 supercilii, the depressor anguli oris, the common and proper elevators of the upper lip, 
 the levator labii inferioris, and the quadratus menti. 
 
 On account of the intimate connexion between the skin of the face and the facial mus- 
 cles, which, from the nature of their insertions, are in some measure identified with it, 
 the frequently-repeated contraction of one or more of these muscles occasions folds oi 
 wrinkles of the skin that remain during the intervals of those contractions, and aftei 
 they have entirely ceased. And thus the continual experience of grave or cheerful emo- 
 tions, with their characteristic expressions of countenance, at length impresses a pecu- 
 liar and permanent stamp upon the features, so that those who are in the habit of close 
 ly observing such circumstances may in some degree judge of the disposition of an indi 
 vidual from an examination of his physiognomy. This is the only foundation of the sys 
 tern of Lavater. 
 
 MUSCLES OF THE TEMPORO-MAXILLARY REGION. 
 The Masseter and Temporalis. 
 The muscles of this region are four in niunber ; two on each side, viz., the massetei 
 and the temporal. 
 
 The Masseter. 
 
 Dissection. — ^Make a horizontal incision along the zygoma, and a vertical one from the 
 middle of this to the base of the jaw ; dissect back the flaps, taking care not to divide 
 the Stenonian duct, which passes over the muscle. In order to see the deep surface, saw 
 through the zygoma in two places, and turn it outward. 
 
 The masseter {s,Jig. 113) is a short and very thick muscle, of an irregularly-quadrilat- 
 eral form, situated upon the side of the face. 
 
 Attachments. — It arises from the lower edge of the zygoma, and is inserted into the 
 outer surface of the angle and ramus of the lower jaw. Its origin from the zygoma 
 consists of a very thick aponeurosis, which embraces the anterior borders of the mus- 
 cles, and is composed of several planes of super-imposed fibres, which are prolonged 
 upon its surface and in its substance for a considerable distance. Tlie fleshy fibres pro- 
 ceed from the inferior surface and the borders of this aponeurosis, obliquely downward 
 and backward, and are inserted into the angle of the jaw either directly or by means of 
 very strong tendinous fibres. Not unfrequently a small triangular fasciculus is detached 
 forward to the inferior border of the body of the bone. The fleshy fibres arising from 
 the posterior portion of the zygoma constitute a short, small, and almost entirely fleshy 
 bundle, which passes vertically downward, and is inserted behind the preceding into the 
 external surface of the ramus of the jaw. Lastly, the zygomatic arch being reversed, 
 we see a still smaller fleshy fasciculus, arising directly from its internal surface, and 
 T^assmg forward, to be inserted into the outer surface of the coronoid process, and into 
 the tendon of the temporal muscle. 
 
 Relations. — It is covered by the skin, from which it is separated by a small fascia, and 
 sometimes by a prolongation of the platysma ; behind, it is covered by the parotid gland, 
 and by the orbicularis palpebrarum and zygomaticus major above. It is crossed at right 
 angles by the divisions of the facial nerve, the transverse artery of the face, and the 
 Stenonian duct. It covers the ramus of the jaw, the temporal and the buccinator mus- 
 cles, from the latter of which it is separated by a collection of fat. Its anterior edge, 
 which is prominent beneath the skin, has an important relation below to the facial ar- 
 tery, which may be compressed against the bone immediately in front of it. The parot- 
 id gland embraces its posterior border. 
 
 Action. — The action of this muscle is very powerful. Its strength in different animals 
 may be in some degree measured by the size of the zygomatic arclu and by the promi- 
 nence of tiie lines and projections on the angle of the jaw. 
 
 Its momentum, i. e., its period of most powerful action, occurs when the jaws are 
 slightly separated, because its angle of incidence with regard to the lever is then nearly 
 perpendicular. The general direction of the fibres of the masseter muscles, obliquely 
 downward and backward, is highly advantageous as regards the trituration of the food, 
 for during the contraction of the two muscles the lower jaw is moved upward and for- 
 ward. This same obliquity explains the action of the muscle in producing luxation of 
 the jaw ; for as its insertion is farther back than it would have been had the fibres been 
 vertical, it follows that, however slightly the jaws may be separated, the condyle is 
 placed in front of the axis, to which all the fibres of the masseter may be referred ; and 
 when this muscle contracts, it increases the peculiar movement performed by the con- 
 dyle in becoming dislocated forward. 
 
240 
 
 MYOIiOGY. 
 
 The Temporalis. 
 
 Dissection. — Having sawn through and turned back the zygoma, remove the fascia 
 covering the temporal region, and the fat surrounding the insertion of the muscle into 
 the coronoid process. In order to gain a view of the deep surface, detach the muscle, 
 either from above downward, by scraping the periosteum from the temporal fossa, or 
 from below upward, after having sawn through the base of the coronoid process. 
 
 The temporal muscle {e', fig. 114), or crotaphyte, so named because it occupies the 
 whole of the temporal fossa {Kporacjioc, the temple), is a broad, radiated muscle, resem- 
 bling a triangle with the base turned upward. 
 
 Attachments. — It arises from the whole extent of the temporal fossa, and from the in- 
 ner surface of the superficial temporal fascia, and is inserted into the edges and summit 
 of the coronoid process. The fleshy fibres all arise directly, either from the temporal 
 fossa, or from the inner surface of the fascia, which, being attached above to the entire 
 length of the temporal semicircular line, and below to the upper edge of the zygomatic 
 arch, is very tense, and thus affords a solid and very strong surface of origin. From 
 these two parts the fleshy fibres converge, and proceeding downward, the anterior ob- 
 liquely backward, the posterior obliquely forward, and the middle vertically, form a fleshy 
 mass, which gradually increases in thickness until its fibres are attached, partly to the 
 external, but chiefly to the internal surface and borders of the terminal aponeurosis. 
 The fibres of this aponeurosis, which are very strong, and radiated at its comm'ince - 
 ment, are collected into the form of a very thick tendon, inserted into the coronoid pro- 
 cess, and called the coronoid tendon. The temporal muscle, in its course from the tem- 
 poral fossa to the coronoid process, undergoes a sort of reflection over the groove at the 
 base of the zygoma. I have often seen a very strong muscular fasciculus arising from 
 the lower part of the temporal fossa and the ridge bounding it below, and inserted by a 
 separate tendon into the internal border of the anterior surface of the ramus of the jaw. 
 Relations. — It is covered by the skin, the aponeurosis of the occipito-frontalis, the an- 
 terior and superior auricular muscles, the superficial temporal arteries, veins, and nerves, 
 and more immediately by the superficial temporal aponeurosis, the zygomatic arch, and 
 the masseter. It covers the temporal fossa, the external pterygoid muscle, a small 
 part of the buccinator, the internal maxillary artery, and the deep temporal vessels. Its 
 thickness is in proportion to the depth of the temporal fossa and the strength of the 
 coronoid process. 
 
 Action. — The strength of the temporal muscle, therefore, may be in some degree 
 measured by the depth of the temporal fossa and the size of the coronoid process. This 
 fact may be demonstrated by an examination of these regions in the skeletons of carniv- 
 orous animals, in which the elevators of the lower jaw are most highly developed. The 
 use of the temporal muscle, like that of the masseter, is to elevate the lower jaw, but 
 the mechanism of its action is diflerent. In fact, the masseter raises the jaw by a direct 
 action ; the temporal muscle, on the contrary, raises it by a sort of swing motion, acting 
 principally upon the back part of the coronoid process. In a word, the temporal muscle 
 acts upon the vertical arm of the bent lever represented by the maxillary bone, while 
 the masseter, on the contrary, acts upon its horizontal arm, the movement depending on 
 the action of the temporal muscle : the lower jaw resembles the curved lever represent- 
 ed by the hammer of a beU. 
 
 THE PTERYGO-MAXILLARY REGION. 
 The Pterygoideus Internus. — The Plerygoideus Externus. 
 The muscles of this region are the external and the internal pterygoids. 
 
 Fig. 115 
 
 The Pterygoideus Internus vel Magnus 
 
 Dissection. — Separate the face and that part of 
 the cranium which is situated anterior to the ver- 
 tebral column from the remainder of the scull, 
 and divide the face into two lateral halves by an 
 antero-posterior section. 
 
 ' This muscle may also be dissected in the fol- 
 lowing manner : saw through the lower jaw ver- 
 tically at the junction of the body and ramus ; re- 
 move the zygomatic arch ; cut through the base 
 of the coronoid process and the neck of the con- 
 dyle, and then disarticulate the latter. 
 
 The internal pterygoid {a, fig. 115) is deeply 
 seated m the zygomatic fossa, along the inner 
 surface of the ramus of the jaw(tertius nmsculus 
 qui in ore latitat, Vesalius). It is thick and quad- 
 
THE PTERYGOIDEttS EXTERNUS, ETC. 
 
 iilateral, and in its form, structure, and direction, bears a remarkable reselrtBlarice to the 
 masseter ; hence Winslow called it the internal masseter. 
 
 Attachments. — It arises from the pterygoid fossa, from the hamular process, at the apex 
 of the internal pterygoid plate, and from the lower surface of the pyramidal process of 
 the palate bone ; and is inserted into the inner surface of the angle of the lower jaw 
 Its origin consists of a tendon resembling that of the msisseter, prolonged upon the in- 
 ternal surface, and into the substance of the muscle. From this the fleshy fibres pro- 
 ceed downward, outward, and backward, to be inserted, by very strong tendinous laminae, 
 into the lower jaw. 
 
 Relations. — On the inside it is in relation with the external peristaphyhne muscle 
 {tensor palcti), and with the pharynx, a triangular interval existing between it and the 
 latter, occupied by a considerable quantity of cellular tissue, vessels, nerves, and the 
 sub-maxillary gland : on the outside it corresponds with the ramus of the lower jaw, 
 from which it is separated above by the dental and lingual nerves, the inferior dental 
 vessels, and the so-called internal lateral ligament of the temporo-maxillary articulation. 
 
 Action. — As this muscle is inserted almost perpendicularly into the lever upon which 
 it acts, it has very great power. Most of the remarks already made concerning the mas- 
 setor apply to this muscle, which is a true internal masseter. It has only this peculiar- 
 ity, that as its origin is nearer the median line than that of the external masseter, it 
 assists in producing a slight lateral movement of the jaw, which is very useful in bruis- 
 ing the food. 
 
 The Pierygoideus Externus vet Parvus. 
 
 Dissection. — This, like the preceding muscle, may be exposed by two opposite methods. 
 
 The external pterygoid {b,fig. 115) is very short, thick, and conoid, smaller than the 
 preceding, and situated in the zygomatic fossa, extending horizontally from the outer 
 surface of the external pterygoid plate to the neck of the condyle of the lower jaw. It 
 arises from the whole outer surface of the external plate of the pterygoid process, and 
 from the facette of the palatine process, at which it terminates below, from the ridge 
 separating the temporal and zygomatic fossae, and from a spinous process at the extrem- 
 ity of this ridge, which appears to me worthy of notice. It is inserted into the fossa in 
 front of the neck of the condyle of the lower jaw, and into the border of the interarticu- 
 lar cartilage. Its origin consists of a strong tendon, prolonged into the substance of 
 the muscle. From this the fleshy fibres proceed horizontally outward and backward, 
 forming, at first, two distinct portions, between which the internal maxillary artery often 
 pjisses : these two portions then converge, are blended together, and terminate by some 
 small tendinous fibres, which form the truncated summit of the cone represented by the 
 muscle, and are attached to the neck of the condyle and to the inter-articular cartilage. 
 
 Relations. — This muscle is deeply situated, and is in relation on the outside with the 
 ramus of the lower jaw, the temporal muscle, and the internal mcixillary artery ; on the 
 inside with the internal pterygoid, and above with the upper wall of the zygomatic fossa. 
 
 Action. — The axis of the external pterygoid being directed outward and backward, 
 and its origin being at the pterygoid process, it may be readily imagined that its con- 
 traction will produce a horizontal motion in two directions, viz., forward and to the op- 
 posite side from that on which the muscle is acting. When the two external pterygoids 
 act together, the jaw is carried directly forward. From the insertion of this muscle into 
 the inter-articular cartilage, the latter is never separated from the condyle during these 
 several movements. It is principally this muscle which causes displacement of the con- 
 dyle in cases of fracture of the neck of the bone, and it is also the chief agent in bruis 
 ing the food. 
 
 MUSCLES OF THE UPPER EXTREMITIES 
 
 The muscles of the upper extremities may be divided into those of the shoulder, oi 
 the ann, of the forearm, and of the hand. 
 
 MUSCLES OF THE SHOULDER 
 
 The Deltoidexis. — Supra-spinatus. — Infraspinatus and Teres Minor. — Subscapularis. 
 
 The muscles of the shoulder are the deltoid, the supra-spinatus, the infra-spinatus 
 and teres minor (which I regard as only one muscle), and the subscapularis. The teres 
 major, generally arranged among the muscles of this region, has already been described 
 with the latissimus dorsi, of which it may be regarded as an accessory. 
 
 The Deltoideus. 
 Dissection. — Make a horizontal incision through the skin, round the summit of the 
 •houlder, extending from the external third of the clavicle to the most distant point of 
 the spine of the scapula : from the middle of this incision let another be made, descend- 
 
 Hh 
 
242 MYOLOGY. 
 
 mg vertically half way down the humerus ; dissect back the two flaps, taking care tc 
 raise at the same time a very thin aponeurosis, which is closely applied to the fibres. 
 
 The deltoid {I, figs. 106, 109), so named from its resemblance to the Greek delta, A, re- 
 versed, is a thick, radiated, triangular muscle, bent in such a way as to embrace the 
 scapulo-humeral articulation before, on the outer side and behind. It is the muscle of 
 the top of the shoulder. 
 
 Attachments. — It arises from the entire length of the posterior border of the spine of 
 the scapula, from the external border of the acromion, and from the external third, i. e., 
 from the concave part of the anterior border of the clavicle : it is inserted into the del- 
 toid impression on the humerus. The scapulo-clavicular origin of the deltoid corre- 
 sponds exactly to the inferior attachment or the insertion of the trapezius, so that these 
 two muscles, although separate and distinct in man, appear to form a single muscle di- 
 vided by an intersection : a view that is perfectly confirmed by a reference to compara- 
 tive anatomy. The origin consists of tendinous fibres ; of these the posterior are the 
 longest, and are blended with the infra-spinous aponeurosis, which also gives origin to 
 some of the fibres of the deltoid. Three or four principal tendinous laminae, attached at 
 regular intervals to the clavicle and the acromion, penetrate into the substance of the 
 muscle, and give origin to a great number of fleshy fibres. The largest of these laminae 
 extends from the summit of the acromion, and its situation is sometimes indicated by a 
 prominence of the skin, particularly during contraction of the muscle. From this very 
 extensive origin the fleshy fibres proceed downward, the middle vertically, the anterior 
 backward, and the posterior forward : they form a thick, broad mass, moulded over the 
 top of the shoulder, and, gradually converging, are at length inserted into the deltoid 
 impression of the humerus by three evry distinct tendons, the two principal of which, 
 the anterior and posterior, are attached to the bifurcations of that V-shaped impression. 
 Not unfrequently some fibres of the pectoralis major are connected with the front of this 
 tendon. 
 
 Relations. — It is covered by the skin, the platysma intervening between them, by 
 some supra-acromial nerves, and by a thin fascia extending from the infra-spinous apo- 
 neurosis, the spine of the scapula and the clavicle, and becoming continuous with the 
 fascia of the arm. It covers the shoulder-joint, from which it is separated by a tendi- 
 nous layer continued from the infra-spinous and coraco-acromial ligaments, and which 
 terminates on the sheaths of the coraco-brachialis and biceps muscles. Between this 
 lamina and the greater tuberosity of the humerus there is a quantity of filamentous cel- 
 lular tissue, and frequently a synovial bursa. The deltoid, therefore, is enclosed in a 
 proper fibrous sheath, and glides over the articulation. It also covers the upper third 
 of the humerus, the coracoid process, the tendons of the pectorales, coraco-brachialis, 
 biceps, supra-spinatus, infra-spinatus and teres minor, teres major, and biceps muscles, 
 also the circumflex vessels and nerves. The anterior border of the deltoid, directed ob- 
 liquely downward and outward, is separated from the external margin of the pectoralis 
 major by a cellular interval, but is frequently in contact with it. The cephalic vein and 
 a small artery define the limits of the two muscles. The posterior border is thin above, 
 where it is applied to the infra-spinatus muscle, and becomes thick and free below. The 
 inferior angle of the deltoid is embraced by the brachialis anticus. Issues are generally 
 established over this situation. 
 
 Remark. — The structure of this muscle has been patiently investigated by some anat- 
 omists, who have counted the exact number of its component fasciculi. Tliese are sep- 
 arated by fibro-cellular prolongations, like the fasciculi of the glutaeus maximus ; some- 
 times, even, the muscle is divided into three distinct portions above, viz., a clavicular, 
 an acromial, and a spinal. Eighteen or twenty small penniform fasciculi, the bases of 
 which are generally turned upward, are collected into a small space by mutually over- 
 lapping each other, and are united by their terminating tendons. Albinus admits ten 
 of these bundles, which he has described separately. 
 
 Action. — The deltoid elevates the shoulder (elevator, attollens humerum). From the 
 threefold direction of its fibres, it has a different action, according to the particular set of 
 fibres employed. The middle fibres raise the humerus directly, the anterior raise and 
 carry it forward, the posterior raise and carry it backward. When the arm is raised, 
 Bichat states that the anterior and posterior fibres can depress it ; but I do not think 
 this possible. There has been no example recorded of luxation from the over-action of 
 this muscle. When the arm is fixed, as in the act of climbing, the aJioulder is moved 
 upon the head of the humerus. The trapezius must be regarded as the most powerful 
 antagonist of the deltoid, since the scapulo-clavicular attachments of both muscles are 
 the same. Thus, we have seen that the diaphragm and the transversalis abdominis are 
 separated only by their costal insertions. The most complete antagonism follows from 
 such an arrangement, for then one fibre is, as it were, opposed to another, having ex- 
 actly an opposite direction. 
 
 The action of the deltoid is, however, less powerfnl than might have been supposed 
 from its size ; it is, in fact, parallel to the lever on which it acts. While almost all other 
 muscles have a mmnentum, occurring at the period when their fibres are inserted at the 
 
THE SUPRA AND INFRA S>ilJiATUS AND TERES MINOR. S48 
 
 most favourable angle, the deltoid, pioperly speaking, has none ; it is parallel to the lever 
 during the entire period of its action. This is the reason vthy the elevation of the arm 
 is so feeble a movement, and why contraction of the deltoid is always accompanied by 
 considerable fatigue. 
 
 The Supra-spinatus. 
 
 Dissectimi. — Take off the trapezius, and, in order to see the whole extent of the mus- 
 cle, remove the clavicle, and saw through the base of the acromion. 
 
 The supra-spinatus {r,fig. 106) is a thick, triangular muscle, broad on the inside, nar- 
 row without, occupying the supra-spinous fossa, and retained therein by a strong apo- 
 neurosis, which completes the osteo-fibrous sheath in which the muscle is enclosed. 
 
 Attachments. — It arises from the internal two thirds of the supra-spinous fossa, and is 
 inserted into the highest of the three facettes on the greater tuberosity of the humerus 
 Its origin from the supra-spinous fossa is partly tendinous and partly fleshy, and sora„ 
 fibres arise from its aponeurotic investments. From these points the fleshy fibres con- 
 verge to a tendon, which is found among them where the muscle reaches the upper part 
 of the joint, and which is slightly reflected over the head of the humerus before reaching 
 its insertion. This has not the shining appearance of other tendons, but has the dull 
 aspect of many ligaments ; it is blended with the fibrous articular capsule, from which 
 it cannot be separated near its insertion. It may even be regarded as forming the upper 
 part of the capsular ligament. 
 
 Relations. — It is covered by the trapezius, the clavicle, the coraco-acromion ligament, 
 and the deltoid ; and it covers the supra-spinous fossa, the supra-scapular vessels and 
 nerves,* and the upper part of the shoulder-joint. Its tendon is often blended with that 
 of the. infra-spinatus, and is separated from that of the sub-scapularis by the long head 
 of the biceps, and the accessory ligament of the capsule. 
 
 Action. — It raises the humerus, and therefore assists the deltoid. Notwithstanding 
 the nmnber of its fibres, and its perpendicular insertion into its lever, it has very little 
 power, on account of the proximity of that insertion to the fulcrum. Its principal action 
 appears to me to have reference to the joint, affording a support to it above, and forming 
 a sort of active arch, the resisting power of which is in proportion to the force tending 
 to thrust the humerus upward against the osteo-fibrous arch, composed of the acromion 
 and coracoid processes and their connecting ligament. There is no muscle, then, to 
 which the name of articular can be more correctly applied. The use of the deep fibres 
 in preventing the folding of the fibrous and synovial capsules, and their compression be- 
 tween the two articular surfaces, though much insisted on by Winslow, appears to me 
 very problematical. 
 
 The Infra-spinatus and Teres Minor. 
 
 Dissection. — ^Detach the scapular origin of the deltoid, and saw through the base of the 
 acromion. 
 
 The infraspinatus (s) and teres minor {t, Jig. 106) constitute a single, thick, triangular 
 aiuscle, broad on the inside and narrow externally, and occupying the infra-spinous fossa, 
 in •rt'hich it is retained by an aponeurosis, exactly resembling that of the supra-spinatus 
 uiuscle. 
 
 It aiises from the internal two thirds of the infra-spinous fossa, from a very strong 
 fascia interposed between it and the teres major and long head of the triceps, and by a 
 'ew fibres from the infra-spinous aponeurosis : it is inserted into the middle and inferior 
 'acettes on the greater tuberosity of the humerus, below the insertion of the supra-spi- 
 natus. It arises from the infra-spinous fossa, directly by fleshy fibres, and also by means 
 uf tendinous fibres attached along the ridges of that fossa. One of these laminae is con- 
 stantly found attached to the ridge situated on the outer side of the infra-spinous groove : 
 ihis has doubtless given rise to the division of the muscle into two parts, called the in- 
 fra-spinatus and the teres minor. From these origins the fleshy fibres proceed, the su- 
 perior horizontally, the next obliquely, and the inferior almost vertically outward : they 
 form a thick, triangular, fleshy body, and become attached to the anterior surface and 
 margins of a flat tendon, which glides upon the concave humeral border of the spine of 
 th,3 scapula, to be inserted into the humerus. Not unfrequently we find the lower fibres 
 of the portion called the teres minor, arising from the posterior surface of the tendon of 
 the triceps, becoming applied to the imder part of the capsular ligament, and inserted 
 into the humerus immediately below the great tuberosity. 
 
 Relations. — These two united muscles are covered by the deltoid, the trapezius, the. 
 Jatissimus dorsi, and the skin ; and they cover the infra-spinous fossa, from which they 
 are separated by the supra- scapular nerves and vessels ; they also cover the capsular 
 ligament of the joint, and a small portion of the long head of the triceps. Their lower 
 or external border corresponds internally or inferiorly with the teres major, an aponett- 
 rotic septum intervening between them, and externally or superiorly with the long head 
 
 jf the triceps. 
 
 * The supra-scapular nerve generally passes through the coracoid notch by itself, and the supra-scapulat 
 lery above the ligament. 
 
244 • ?:'.»,«r^ ' MYOLOGY 
 
 Action. — This muscle rotates the humerus t,atward and a little backward. When the 
 arm is raised, it assists in keeping it in this position, and carries it backward. But an 
 important use of this muscle is that of retainmg the head of the humerus in its place, pre- 
 venting its displacement backward, and protecting the posterior part of the articulation. 
 
 The Sub-scapularis. 
 
 Dissection. — Detach the upper extremity, including the shoulder, from the trunk of the 
 body ; remove from the inner surface of the muscle the cellular tissue, the lymphatic 
 glands, the brachial plexus, the axillary vessels, and the serratus magnus ; and dissect 
 off, with care, the thin fascia which invests it. 
 
 The sub-scapularis (a, figs. 110, 116) is a thick triangular muscle, occupying the whole 
 of the sub-scapular fossa, beneath the axillary border of which it passes : by itself it rep- 
 resents the supra and infra spinatus and teres minor, upon the posterior scapular region. 
 We not unfrequently meet with tendinous laminae dividing it into three parts, which cor- 
 respond to those three muscles. 
 
 Attachments. — It arises from the internal two thirds of the sub-scapular fossa, by ten- 
 dinous laminae attached to the oblique ridges already described as existing on that part 
 of the scapula ; also from the anterior lip of the axillary border of the scapula by an apo- 
 neurosis, which separates this muscle from the teres major and the long head of the tri- 
 ceps. Very frequently the lowest fibres arise from the anterior surface of this head of 
 the triceps, just as we have seen that the lower fibres of the teres minor take their ori- 
 gin from the posterior surface of the same head of that muscle. From these different 
 origins the fleshy fibres all proceed outward, the upper horizontally, and the lower ob- 
 liquely, gradually approaching more and more to the vertical direction. The muscle, 
 therefore, becomes progressively narrower and thicker, until its fibres are attached to 
 the two surfaces and borders of a tendon which is inserted into the entire surface of 
 the lesser tuberosity of the humerus. Some of the muscular fibres are inserted below 
 the tuberosity ; and I have seen the inferior fibres of the muscle attached for a certain 
 extent to a fibrous prolongation that completes the bicipital groove behind. 
 
 Relations. — The posterior surface of this muscle lines the sub-scapular fossa, which it 
 entirely fills, and from which it is separated at the outer third by some cellular tissue 
 and the sub-scapular vessels and nerves ; more externally, it covers the upper and anterior 
 part of the capsular ligament of the shoulder-joint, turning around it, and becoming iden- 
 tified with it at its insertion. Its anterior surface is in relation with the serratus magnus, 
 the sub-scapular fascia, and some very loose cellular tissue intervening between them ; 
 also with the axillary vessels and nerves, and with the coraco-brachialis and deltoid 
 muscles. The upper border of its tendon glides in the hollow of the coracoid process, 
 which serves as a pulley, and forms with the coraco-brachialis and the short head of the 
 biceps a sort of ring, partly bony and partly muscular, in which the tendon is retained. 
 Between this tendon and the coracoid process there is also a synovial bursa, which some- 
 times extends over the tendons of the biceps and coraco-brachialis, and always commu- 
 nicates with the synovial capsule of the shoulder-joint.* 
 
 Action. — It is essentially a rotator inward of the humerus. In proof of this, we find 
 that the muscie is stretched when the arm is rotated outward, and relaxed when it is ro- 
 tated inward. The movement of rotation is much more considerable than the length of 
 the neck of the humerus would lead us to imagine, and this arises from the muscle turn- 
 ing round the head of the bone. As a rotator muscle, then, it is congenerous with the 
 latissimus dorsi. When the humerus is raised, the sub-scapularis tends to draw it down- 
 ward. And farther, this muscle, as well as the supra-spinatus, infra-spinatus, and teres 
 minor, is essentially an articular muscle, and is sometimes completely identified with the 
 anterior part of the fibrous capsule : in all cases it offers an active resistance to displace- 
 ment forward, and is, therefore, always torn in this kind of dislocation. 
 
 MUSCLES OF THE ARM. 
 The Biceps. — Brachialis Anticus. — Coraco-brachialis. — Triceps Extensor Cubiti. 
 The muscles of the arm have been divided into those of the anterior region, viz., the 
 biceps, the coraco-brachialis, and the brachialis-anticus ; and those of the posterior region, 
 which constitute the single muscle called the triceps. 
 
 Anterior Brachial Region. 
 The Biceps. 
 Dissection. — Make a vertical incision through the skin from the middle of the clavicle 
 to the middle of the bend of the elbow ; dissect back the flaps, and divide longitudinally 
 the brachial fascia, which is united to the biceps by very loose cellular tissue ; preserve 
 the vessels and nerves which lie along the inner border of the muscle. Expose the up- 
 per part of the muscle by detaching the pectoralis major and deltoid from their clavicu- 
 
 * See note, p. 22. 
 
THE BICEPS. 
 
 Fig. 116. 
 
 tax origins, and turning them inward and outward. In order to trace the whole extent 
 of the long head of the biceps, open the capsular ligament above ; and to see the radial 
 insertion of the muscle, flex the forearm to a right angle upon the arm, and supinate it 
 forcibly ; it is better, however, to wait until the muscles of the anterior region of the fore- 
 arm are dissected. 
 
 The biceps flexor cubiti (a, flg. 116) is along muscle forming the superficial layer of the 
 anterior region of the arm ; it is divided above into a short and 
 long head ;* and hence its name biceps. 
 
 Attachmcjits. — It arises by its short head from the apex of the 
 coracoid process, and by its long head from the top of the glenoid 
 cavity ; and is inserted into the bicipital tuberosity of the radius. 
 
 The origin of the short or coracoid head {b,fig. 116) consists 
 of a flat and very thick tendon, common to it and the coraco- 
 brachialis, and terminating in front of this part of the muscle in 
 an aponeurosis, from which is given off a tendinous septum, be- 
 tween the biceps and the coraco-brachialis. The long, glenoid, 
 or reflected head arises by a tendon apparently forming a contin- 
 uation of the glenoid articular border, which penetrates into the 
 interior of the joint, turns over the head of the humerus, upon 
 which it is reflected, and thus reaches the bicipital groove. It 
 is retained in this groove by a sort of fibrous bridge or canal, 
 traverses the whole of its extent, and ends in a sort of tendinous 
 cone open behind, from the interior of which the fleshy fibres 
 take their origin. These fibres are collected into a rounded belly, 
 which, about the middle of the arm, is applied to the muscular 
 belly of the short portion, equally rounded and of variable size, 
 and ultimately becomes identified with it. The single muscle 
 (fl, fig. 116) thus formed is very thick, flattened from before 
 backward, and directed vertically like the two original fasciculi. 
 Its fibres are attached to the surfaces and edges of an aponeuro- 
 sis, which gradually becomes narrower and thicker, until it emerges in the form of a free 
 tendon opposite the lower end of the humerus, a little nearer to the outer than the inner 
 side. This flattened tendon sinks downward and backward into the triangular space be- 
 tween the supinator longus and the pronator teres, and is then so folded and twisted upon 
 itself that its anterior surface becomes posterior, its internal margin becomes anterior, 
 and its external margin at first posterior and then superior. This folding and torsion are 
 of extreme utility in preventing displacement of the muscle, which thus fastens down it- 
 self The tendon of insertion having given off from its anterior surface and external 
 margin a broad aponeurosis, constituting the principal origin of the fascia of the fore- 
 arm, glides over the bicipital tuberosity of the radius, from which it is separated by a 
 bursa, and is inserted into the posterior part of that process. 
 
 Relations. — The upper third of the two heads of the biceps, as well as the coraco-brach- 
 ialis, and the axillary vessels and nerves, are contained in the cavity of the axilla, be 
 tween the pectoralis major and the deltoid in front, and the latissimus dorsi and teres 
 major behind. In this part of its course, the short head of the biceps is in relation Witt 
 the coraco-brachialis on the inside, and behind with the sub-scapularis, which separates 
 it from the shoulder-joint ; a bursa intervenes between these two muscles. The tendon 
 of the long head is in contact with the head of the humerus, and surrounded by the sy- 
 novial membrane, which isolates it from the cavity of the joint, and accompanies it, for 
 a greater or less distance, along the bicipital groove. Below the axilla the biceps is sub- 
 cutaneous in front, the brachial fascia intervening between it and the skin, through which 
 it is very clearly defined ; behind, it is in relation with the musculo-cutaneous nerve, and 
 the coraco-brachialis and brachialis anticus muscles ; on the inside, with the brachial ar- 
 tery and its accompanying veins, and with the median nerve, all of which lie along its in- 
 ternal border, by the projection of which they are protected. The tendon is embraced at 
 its insertion by the supinator brevis, and it is separated from that of the brachialis anti- 
 cus by a bursa. Great attention should be paid to the relation of this muscle to the brach- 
 ial artery. I am accustomed, when speaking of the surgical anatomy of these parts, 
 to call the biceps the satellite muscle of the brachial artery. It is worthy of remark, that 
 the relative positions of the long and the short head are altered as the humerus is rota- 
 ted inward or outward ; in rotation inward, the long head is placed behind the other, or 
 even crosses to the inner side of it ; but in rotation outward, the interval between the 
 two heads is considerably increased. 
 
 Action. — The biceps flexes the forearm upon the arm, and at the same time supinates it. 
 This last effect results from the insertion of the muscle into the inner and back part of 
 the bicipital tubercle of the radius. The momentum of the biceps occurs during seini- 
 
 * Not unfrequently the biceps is trifid above. The supernumerary head is internal, and arises from the in- 
 ner border of the humerus, below the coraco-brachialis, which may be regarded as the continuation of this 
 head, for they correspond in size. This supernumerary portion is attached to the inner edge and posterior 
 surface of the lower tendon of the biceps. 1 have twice seen this disposition of parts. 
 
246 MYOLOGY. 
 
 flexion of the forearm • its insertion being at that period perpendicular to tiie lever, the 
 disadvantage arising from its proximity to the fulcrum is then counteracted. The length 
 of Its fibres explains the extent of the movement of flexion. By means of its scapular 
 attachments, the biceps acts upon the arm, either secondarily, after bending the forearm, 
 or primarily, when the forearm is extended. By means of both its heads, it carries the 
 arm forward, and thus co-operates with the anterior fibres of the deltoid and coraco-brach- 
 ialis. The two heads also assist in strengthening the shoulder-joint. The long head 
 forms a sort of fibrous arch, which supports the head of the humerus, and retains it in the 
 glenoid cavity. The short head, together with the coraco-brachialis, forms a continuation 
 of the hook of the coracoid process, and protects the anterior and inner part of the joint. 
 
 The biceps is, as Winslow first showed, one of the principal supinators of the forearm ; 
 and it is in this movement that the tendon glides over the bicipital tuberosity of the ra- 
 dius by means of the intervening bursa. This tuberosity is almost entirely intended for 
 the tendon to glide over ; it is, therefore, incrusted with cartilage. Dense and reddish 
 granulations, as pointed out by Haller, are found upon the synovial bursa of the tendon. 
 
 When the forearm is fixed, as in climbing, the biceps flexes the arm upon the fore- 
 arm, and the scapula upon the arm. Lastly, it is a tensor of the fascia of the forearm, 
 upon which the internal fibres of the muscle often terminate. 
 
 The Brachialis Anticus. 
 
 Dissection. — Cut the biceps across, opposite the insertion of the deltoid, and turn down 
 the lower part upon the forearm. 
 
 The brachialis anticus (brachialis internus, Alb., d d,fig. 116; d,fig. 117) is a thick, 
 prismatic, and triangular muscle, situated behind the preceding. It arises from the hu- 
 merus, below the insertion of the deltoid, which it embraces by a well-marked bifurca- 
 tion ; and since the point of insertion of the deltoid is not always the same, it follows that 
 this origin of the brachialis anticus is eilso variable ; it also arises from the internal and 
 external surfaces, and from the three borders of the humerus, and from the external and 
 internal inter-muscular septa. It is inserted into the rough surface on the fore part of the 
 coronoid process of the ulna. The different origins from the humerus are fleshy, the 
 fibres being of very various lengths, and proceeding in different directions ; the middle 
 pass vertically downward, the external somewhat obliquely inward, and the internal out- 
 ward ; they all terminate on the posterior surface of an aponeurosis, which is broad and 
 thin above, and thick below, especially on the outer side, where it turns round so as to 
 embrace the outer border of the muscle, and forms a deep aponeurotic lamina. The 
 fleshy fibres, therefore, are received into a semi-cone of tendinous substance, open on 
 Che inside, the fibres of which are collected together, and finally inserted into an oblique 
 line, running downward and outward, below the coronoid process of the ulna. 
 
 Relations. — The anterior surface of the brachialis anticus is in relation with the biceps, 
 the musculo-cutaneous nerve, the brachial fascia, the brachial artery and veins, and the 
 median nerve ; its internal surface, with the pronator teres muscle, the ulnar nerve, and 
 the triceps, from which it is only separated by the internal inter-muscular septum ; its 
 external surface, with the supinator longus and the extensor carpi radialis longior, which 
 are received into a sort of groove presented by it, the radial nerve establishing the limit 
 between these two muscles and the brachialis anticus. The posterior surface embraces 
 the internal and external surfaces of the humerus, to which it is attached ; below, it em- 
 braces, and effectually protects the front of the elbow-joint, into the anterior ligament of 
 which many of its fibres are inserted. 
 
 Action. — The brachialis anticus flexes the forearm upon the arm, and, reciprocally, the 
 arm upon the forearm. Its momentum takes place, like that of the biceps, during semi- 
 flexion. It is worthy of remark, that this muscle acts with greater precision than the bi- 
 ceps upon the forearm, because it arises from the humerus only, and, besides that, it be- 
 longs more especially than that muscle to the elbow-joint. I have already said that it 
 may be regarded as the active anterior ligament of this articulation. In fact, it so com- 
 pletely hmits the movement of extension, that we cannot imagine the possibility of lux- 
 ation of the forearm backward without rupture of this muscle. From the insertion of 
 the biceps into the radius, and of the brachialis anticus into the ulna, it follows that the 
 flexor muscles of the forearm are divided between the two bones, in the same manner 
 as those of the leg are distributed to the tibia and fibula Thus, the contraction of the 
 brachialis anticus has a tendency to carry the forearm outward as well as to flex it, 
 while that of the biceps tends to draw it inward. When the two muscles contract si- 
 multaneously, direct flexion is the result. 
 
 The Coraco-brachialis. 
 
 Dissection. — The upper part is exposed as soon as the deltoid is detached ; the middle 
 is situated between the pectoralis major and the latissimus dorsi ; and the lower part is 
 seen upon the mner surface of the humerus, near the tendon of the deltoid. 
 
 The coraco-brachialis {e,figs. 116, 117) is the smallest muscle of the arm. It is situa- 
 ted at the inner and upper part of the arm, and was confounded by most of the oldei 
 
THE TRICEPS EXTENSOR CUBITI. 
 
 «4T 
 
 anatomists with the short head of the biceps, with which, indeed, it is intimately united 
 at its upper part. 
 
 Attachments. — It arises from the apex of the coracoid process, and is inserted towards 
 the middle of the internal surface and border of the humerus. It arises from between 
 two tendinous layers, the most superficial of which is common to it and the short head 
 of the biceps, and also from the septum between these two muscles. From this origin 
 the fleshy fibres proceed, forming an elongated, thin, and flat bundle, the size of which is 
 always in an inverse ratio to that of the short head of the biceps ; this bundle passes 
 downward, backward, and a little outward, to be inserted into the humerus, between the 
 brachialis anticus and the triceps. Its insertion is effected by means of a flat tendon, 
 which receives the fleshy fibres successively upon its edges and external surface, and is 
 accompanied by them even to its attachment to the bone. The precise situation of the 
 attachment varies like that of the deltoid, and hence the different statements of authors 
 regarding this point. According to Winslow, the coraco-brachialis is inserted at the up- 
 per part of the middle third of the humerus ; according to M. Boyer, in the middle of the 
 bone ; and according to Bichat, a little above its middle. I have found it inserted at 
 the junction of the lower with the two upper thirds. 
 
 Relations. — It is covered by the deltoid, the pectoralis major, and the biceps, and it 
 covers the sub-scapularis, the latissimus dorsi, and the teres major. Its relations to the 
 axillary and brachial arteries, and the median and musculo-cutaneous nerves, are the 
 most important. Above, it covers these parts, and then it is in relation with the outer 
 side of the brachial artery and median nerve, so that its tendon alone separates the ves- 
 sel from the bone. The musculo-cutaneous nerve passes through it ; hence the name 
 of -perf mains Casserii has been given to this muscle. It is also very frequently perfora- 
 ted by one of the branches of origin or roots of the median nerve. 
 
 Action. — It cames the arm forward and inward, and, at the same time, elevates it 
 It co-operates with the anterior fibres of the deltoid, and the superior fibres of the pecto- 
 ralis major. If the arm be fixed, it depresses the top of the shoulder ; when the arm is 
 carried backward and turned inward, it draws it forward again, and rotates it outward.* 
 
 Posterior Brachial Region. 
 
 The Triceps Extensor Cubiti. 
 
 Dissection. — It is exposed by simply removing the skin and the fascia from the back 
 of the arm, by removing the deltoid, or turning it upward, and by tracing the long head 
 of the muscle between the teres major and minor to the axillary border of the scapula. 
 In order to render it tense, and thus facilitate the dissection, the forearm must be flexed 
 and the humerus abducted. 
 
 The triceps extensor cubiti {ifg,fig. 117) is a very large muscle, divided above into three 
 portions, named the external, internal, and middle, or 
 long heads. It constitutes by itself the entire muscular 
 apparatus of the posterior region of the arm. 
 
 Attachments. — It arises, 1. By its long head, from the low- 
 er part of the glenoid cavity of the scapula, and from a 
 rough, triangular depression existing on the contiguous 
 portion of its axillary border ; 2. By its external head 
 (vastus extemus), from all that portion of the posterior 
 surface of the humerus which is above the groove for the 
 radial nerve, from the external border of that bone, and 
 from the external inter-muscular septum ; 3. By its inter- 
 nal head (vastus intemus), from the whole of the poste- 
 rior surface of the humerus below the groove for the ra- 
 dial nerve, from the internal border of the bone, and from 
 the internal inter-muscular septum. It is inserted into 
 the back of the olecranon. 
 
 The origin of the middle or long head (which we shall 
 find to be analogous to the rectus cruris)t consists of a 
 tendon that is blended with the glenoid ligament, nearly 
 in the same manner as the long tendon of the biceps. 
 This tendon is flattened from before backward, and soon 
 splits into two layers, united by their outer edges, the 
 posterior of which is thin and short, while the anterior 
 is very thick, especially at its outer edge, and prolonged 
 to the middle of the muscle. The head of the humerus, 
 therefore, is bound by the long head of the triceps below, 
 in the same manner as by the long tendon of the biceps 
 
 * I have seen a small supernumerary coraco-brachialis extending from the base of the corait't ."v**.^ 
 below the lesser tuberosity of the humerus, immediately beneath the insertion of the sub-scapularis : the same 
 arrangement existed on both sides. This small muscle described a curve in front of the sub-soapularis. 
 
 t The older anatomists regarded this long portion as a separate muscle : longus [Riolanus Albirms), cubitum 
 Rxtendentium primus (Yesalius), le grand ancone (Winslow). 
 
248 a!Y'):,'|(;y. 
 
 above. The fleshy fibres arise from between the two layers above mea^.o.icu, and form 
 a bundle flattened in front and behind, which irnmediately turns upon itself, so that its 
 anterior surface becomes posterior, and vice versa. From this sort of torsion the strong- 
 est layer of the tendon, which was originally in front, eventually occupies the posterior 
 surface of the muscle. The fleshy fibres arising from between the two layers, and es- 
 pecially from the anterior surface and borders of the now posterior tendon, pass down- 
 ward and a little outward, to be inserted, some into the anterior, but the greater number 
 into the posterior surface of an aponeurotic expaosion, the external border of which is 
 continuous with a similar structure belonging to the external division of the muscle. 
 The aponeurotic fibres are collected together into a very thick tendon, which is folded 
 into a semi-cone, within which the fleshy fibres terminate ; the tendon itself is inserted 
 by a thick mass into the inner and back part of the olecranon, on the outer side of the 
 internal portion of the muscle, and closely united with the posterior aponeurosis of the 
 external portion. A synovial capsule intervenes between this tendon and the olecranon. 
 
 The origins of the external and internal portions from the humerus divide between 
 themselves, so to speak, the posterior surface of that bone, to which the long head has 
 no attachments. 
 
 The external head {f,figs. 116, 117), which is larger than the internal, and, from analo- 
 gy, may be termed the vastus externus of the triceps brachii (cubitum extendentium secun- 
 dus, Vesalius ; ancon6 externe, Winslow), arises partly by fleshy and partly by tendinous 
 fibres. They are bounded above by a rough line, which is very well marked in powerful 
 individuals, extending obliquely from the lower part of the head of the humerus to its 
 external border. From these different origins the fleshy fibres proceed dovnward and 
 inward, become partly blended with the internal head, and are almost all attached to the 
 anterior surface of the terminal aponeurosis of the long head, and to the anterior sur- 
 face and external edge of a very broad and strong tendon, which occupies the posterior 
 aspect of the muscle. This latter tendon is united internally with the tendon of the long 
 head, is folded upon itself, and receives the fleshy fibres as far as its insertion into the 
 olecranon, on the outside of the long head. The inferior fleshy fibres of this portion of 
 the muscle are very short and horizontal, and seem to be continued by the anconeus. 
 
 The internal head of the triceps (tertius cubitum extendentium, Vesalius ; ancone in- 
 terne, Winslow, g, figs. 116, 117), which we denominate the vastus internus of the triceps 
 brachii, might be called the deep and internal portion of this muscle, for, as we find with 
 regard to the vastus internus of the thigh, it is almost entirely covered by the other two 
 portions. Its origins are partly fleshy and partly tendinous. The fibres pass in differ- 
 ent directions, the external downward and inward, a few to the anterior surface of the 
 aponeurosis of the external head, by which they are concealed, but the greater number 
 directly to the olecranon, in front of the insertion of the other portions. The internal 
 pass downward and outward, and terminate, some upon the inner edge and anterior sur- 
 face of the tendon of the long head, but the greater number directly upon the olecranon, 
 to the inside of that tendon. The lowest of these fibres are almost horizontal. Somt 
 of the deepest fasciculi are generally given off from the body of the muscle, to be insert- 
 ed into the synovial capsule of the elbow-joint. 
 
 Relations. — It is covered through nearly its whole extent by the brachial fascia, and 
 separated by it from the skin, through which it is distinctly defined ; it covers the poste- 
 rior surface of the humerus, the back of the elbow-joint, the radial nerve, and the deep 
 humeral artery. It is separated from the muscles of the anterior region of the arm by 
 the external and internal inter-muscular septa. Its long or scapular portion is in relation 
 with the deltoid and the teres minor behind, and with the sub-scapularis, the teres major, 
 and the latissimus dorsi in front. 
 
 Action. — The triceps extends the forearm upon the arm, but in order that its long head 
 may act with effect, the scapula must be fixed by other muscles. The power of this 
 muscle is not so great as its size and the number of its fibres would indicate, on account 
 of its disadvantageous insertion near the fulcrum. It is true that here, as in the case 
 of the triceps femoris, nature has, as much as possible, counterbalanced this disadvan- 
 tage by inserting the muscle, not into the apex, but into the back part of the olecranon. 
 We even find, as we have said, a synovial bursa between the tendon and that part of the 
 olecranon with which it is in contact. It would appear, at first sight, that the momentum 
 of this muscle would occur during semi-flexion, but a little consideration would show 
 that, like the triceps femoris, it has, properly speaking, no momentum ; and that the ole- 
 cranon, which may be regarded as the ossified tendon of the muscle, always has the same 
 relation to the ulna, whatever be the position of the forearm. It should also be observ- 
 ed, that this muscle has not nearly so much power during semi-flexion as during exten- 
 sion, because, in the former case, it is opposed by the flexor muscles, which, in that po- 
 sition, act with the greatest possible effect ; while in the latter, when the arm and fore- 
 arm form an obtuse angle, the extensor muscle has the advantage. Lastly, the predom- 
 inance of the extensor over the flexors is less marked in the arm than in the thigh ; and 
 even supposing the extensor to possess more intrinsic power, it has less active force, 
 in consequence of the insertions of the flexors being much more favourable, both as 
 
THE PRONATOR TERES. 
 
 349 
 
 legards their distance from the fulcrum, and their nearer approach to a perpendicular 
 direction. Thus flexion evidently predominates at the elbow, and extension at the knee. 
 This, indeed, ought to be the case, for in the upper extremities the flexion of the elbow 
 is the movement of attraction and prehension ; while in the lower extremities, the ex- 
 tension of the knee is an essential position in standing, walking, running, and leaping. 
 
 We might suppose the possibility of rupture of the olecranon at its junction with the 
 coronoid process, during violent extension o{ the forearm, an accident that would be anal- 
 ogous to fracture of the patella, or rupture of its ligament. The long head of the tricepa 
 assists in drawing the humerus backward, and slightly adducts the arm. By means oi 
 its tendon of origin from the scapula, and especially by the outer edge of that tendon, 
 which is thick, and, £is it were, arched, so as to fit the head of the humerus, the long 
 head also forms a cord which supports the bone during abduction, and tends to prevent 
 its displacement ; but, as the glenoid cavity is directed forward, and as its inferior ex- 
 tremity is situated almost at the junction of the two anterior thirds with the posterior 
 third of the cavity, it follows that this tendon is well calculated to prevent dislocation 
 backward, but offers no resistance to displacement forward. Sometimes the lower ex 
 tremity of the triceps becomes its fixed point, and then it extends the arm upon the fore- 
 arm, and the shoulder upon the arm. 
 
 MUSCLES OF THE FOREARM. 
 
 Fig 118. 
 
 The Pronator Teres. — Flexor Carpi Radialis. — Palmaris Longus. — Flexor Carpi Ulnaris. 
 — Flexor Sublimis Digitorum. — Flexor Profundus Digitorum. — Lumbricalcs. — Flexor 
 Longus Poinds. — Pronator Quadratus. — Supinator Longus. — Extensores Carpi Radia- 
 lis, Longior et Brevior. — Supinator Brevis. — Extensor Communis Digitorum. — Extensor 
 Digiti Minimi. — Extensor Carpi Ulnaris. — Anconeus. — Abductor Longus Pollicis. — Ex- 
 tensor Brevis Pollicis. — Extensor Proprius Indicis. 
 
 The muscles of the forearm are divided into those of the anterior, the external, and 
 the posterior regions. 
 
 Muscles of the Anteeior Region. 
 These muscles form four very distinct layers. The first consists of the pronator teres, 
 the flexor carpi radialis, the palmaris longus, and the flexor carpi ulnaris ; the second is 
 formed by the flexor sublimis digitorum ; the third by the flexor profundus digitorum and 
 the flexor longus pollicis ; and the fourth by the pronator quadratus. 
 
 The Pronator Teres. 
 
 Dissection. — This muscle is exposed when the inner and anterior part of the fascia of 
 the forearm is removed. Its origin should be carefully studied. 
 
 The pronator teres, or rotundus {a, fig. 118), the most superficial mus- 
 cle on the anterior and inner aspect of the forearm, forms an oblique 
 ridge under the skin, upon the inner side of the bend of the elbow. 
 It is attached above to the inner condyle of the humerus, or epitroch- 
 lea (a, fig. 1 19), and is inserted below into the middle of the radius (a')- 
 It arises from the lower part of the inner border of the humerus, from 
 the inner condyle, from a large inter-muscular septum, separating it 
 from the flexor carpi radialis and the flexor sublimis, and from the 
 coronoid process of the ulna on the inner side of the brachialis anti- 
 cus, by means of a tendinous and fleshy bundle, which is separated 
 from the rest of the muscle by the median nerve. From these ori- 
 gins the fleshy fibres proceed obliquely downward and outward (pro- 
 nateur oblique, Winsl.), surrounding a flat tendon, which appears first 
 on the anterior surface of the muscle, and then turns over the ante- 
 rior and external surfaces of the radius, to be inserted at the middle 
 of that bone. The muscle, therefore, turns spirally around the radius, 
 but not so completely as the supinator brevis. Its insertion may take 
 place opposite any point in the middle third of the bone. 
 
 Relations. — It is covered by the fascia of the forearm, by the su- 
 pinator longus and extensor carpi radialis, and by the radial artery 
 and musculo-spiral nerve : it covers the brachialis anticus and flexor 
 sublimis, the median nerve by which it is first perforated, and the 
 ulnar artery. 
 
 Action. — The greater the amount of supination of the forearm, the 
 more effectual is the action of this muscle as a pronator, because 
 then it is much more completely rolled around the radius. I may 
 remark that, on account of its obliquity, it is inserted into the radius 
 at an angle of 45" ; and that, consequently, the direction in which it 
 operates is rather favourable. It acts with greater advantage in pro- 
 portion as it is mserted nearer to the upper end of the radius ; and, for this reason, it» 
 
 Ii 
 
250 MYOLOGY. 
 
 power must vary considerably in different individuals. When pronation is carried asj 
 as possible, the muscle then becomes a flexor of the forearm. After the preceding i 
 amination of this muscle, we need no longer be surprised at the great energy of the mo^ 
 ment of pronation, which is much more powerful than that of supination ; nor yet that 
 is the most natural position of the forearm, for the pronator teres can more than coui 
 teract the two supinators taken together. In fracture of the bones of the forearm, tb. 
 muscle tends to obliterate the interosseous space. 
 
 The Flexor Carpi Radialis. 
 
 Dissection. — It is sufficient to divide and dissect off the anterior part of the fsiscia o! 
 the forearm, in order to expose this muscle, which may be recognised by the followinj 
 description : 
 
 The flexor carpi radialis (radialis intemus, Albinus, I, fig. 118) is situated immediatelj 
 within the pronator teres, occupying the superficial layer of the anterior aspect of tht 
 forearm, and being, as far as its tendon is concerned, the most superficial of all these 
 muscles. It arises from the lower part of the internal border and from the inner con- 
 dyle of the humerus {b,fig. 119), and is inserted {h') into the second metacarpal bone. 
 Its origin consists of a tendon common to it and to the pronator quadratus, palmaris 
 longus, flexor sublimis, and flexor carpi ulnaris. The fleshy fibres immediately arise 
 from within a sort of pyramidal aponeurosis given off by this common tendon, and from 
 the body of the muscle, at first slender, then increasing in size, and again tapering to- 
 wards its attachment to the two surfaces and edges of a tendon, which forms the lower 
 two thirds of the muscle, and passes obliquely outward and downward to the level of the 
 OS scaphoides ; it there penetrates into a groove formed by the scaphoid and the trape 
 zium, is reflected inward along this oblique groove, and terminates upon the second met- 
 acarpal bone, spreading out so as to embrace its upper extremity ; it also gives off a ten- 
 dinous expansion to the trapezium, and sometimes one to the third metacarpal bone. 
 
 Relations. — It is covered by the fascia and the skin, through which it is very clearly de- 
 fined : it is in relation behind with the flexor sublimis ; on the outside, with the tendon 
 of the flexor pollicis, over which it passes at an acute angle, so as to bind it down ; and 
 lower down, with the wrist-joint. A very strong tendinous sheath, concealed by the ab- 
 ductor brevis and opponens pollicis, completes the groove formed by the scaphoid and 
 trapezium for its tendon, the movements of which are facilitated by a well-marked sy- 
 novial membrane.* Its most important relation is that of the external border of its ten- 
 don with the radial artery. The superficial position of the tendon prevents our feeling 
 the artery when the muscle is contracted. 
 
 Action. — It flexes the second row of the carpus upon the first, and this, again, upon the 
 forearm. Moreover, on account of its reflection, it is a pronator, and, according to 
 Winslow, it is a more powerful supinator than the supinator longus. Its obliquity down- 
 ward and outward explains why it inclines the hand to the radial border of the forearm, 
 and thus acts as an abductor. 
 
 The Palmaris Longus. 
 
 Although this small muscle is rather a tensor of the palmar fascia than a flexor of the 
 hand, I have yet judged it proper to describe it in this place, in connexion with the flexor 
 carpi radialis, which, in contradistinction to this muscle {le petit palmaire), has also been 
 called le grand palmaire {Bichat). It is a small fusiform, slender, fleshy bundle {c,fig. 
 118), of about four inches in length, arising {c,fig. 119) from the inner condyle of the 
 humerus to the inner side of the preceding muscle, and from a small tendinous cone, 
 which isolates it from that muscle, the flexor sublimis, and the flexor carpi ulnaris. The 
 fleshy fibres terminate around a flat tendon, which constitutes the lower two thirds of 
 the muscle (whence the name palmaris longus), proceeds vertically downward and a little 
 outward, and terminates by expanding in front of the anterior annular ligament {g, figs. 
 118, 119) of the wrist, and becoming continuous with the middle palmar fascia (c', fig. 118). 
 
 This muscle is subject to a great many varieties, and is often wanting ; its fleshy belly 
 is sometimes very long, and occasionally occupies the middle of the muscle. 
 
 Relations. — The same as those of the preceding muscle {flexor carpi radialis) ; its ten- 
 don is very superficial. It is separated from the neighbouring muscles by a very strong 
 sheath. 
 
 Action. — It is a tensor of the palmar fascia. When this effect has been produced, it 
 flexes the hand upon the forearm. According to Winslow, it would assist the flexor 
 carpi radialis in pronation. 
 
 The Flexor Carpi Ulnaris. 
 
 Dissection — Remove the superficial layer of the fascia covering the inside of the 'ire- 
 arm, taking care, in dissecting this as well as the other muscles of the forearm, to stop 
 at the points where that fascia adheres intimately to the fleshy fibres. 
 
 * See note, p. 296. 
 
THE FLEXOR SUBLIMIS DIGITORUM. 
 
 251 
 
 This is the most deep-seated of all the muscles of the superficial layer of the forearm 
 (ulnaris internus, Alhinus ; cubital interne, Winslow, d,figs. 118, 119, 121, 122). 
 
 It arises from the inner condyle of the humerus and from the inner edge of the ole- 
 cranon, these two origins forming an arch under which the ulnar nerve passes. It also 
 arises sometimes, though slightly, from the coronoid process of the ulna, from the upper 
 half of the posterior border of the ulna, through the medium of the fascia of the forearm, 
 and from the septum between itself and the flexor sublimis. It is inserted into the pisi- 
 form bone. The origin from the ridge on the ulna is remarkable ; it consists, indeed, of 
 the fascia of the forearm, which becomes thickened and divided into two layers, one 
 deep and very thin, the other superficial and very thick ; in the interval between these 
 the fleshy fibres arise. These fibres are attached to the surfaces and edges of a very strong 
 tendon, which then appears upon the anterior border of the muscle, and continues to re- 
 ceive the fleshy fibres on its posterior edge until its insertion into the pisiform bone. 
 This takes place upon the anterior surface of the bone, like those of the triceps muscles 
 of the arm and thigh into the olecranon and pateUa. The tendon then becomes continu- 
 ous with the inferior vertical ligament of the articulation between the pisiform and cunei- 
 form bones, so that the muscle may, in fact, be regarded as inserted into the fifth meta- 
 carpal bone. 
 
 Relations. — It is covered by the fascia, and is intimately united with it for a consider- 
 able extent : it covers the ulnar artery and nerve, the flexor sublimis, the flexor profun- 
 dus, and the pronator quadratus. The most important of all its relations is that with the 
 ulnar artery, which is at first under it, and then lies along the external edge of its ten- 
 don, which protects the artery, and serves as a guide in the application of a ligature to it. 
 I have, therefore, been in the habit of calling this muscle the satellite of the ulnar artery. 
 Action. — This muscle acts as if it were inserted into the upper extremity of the fifth 
 metacarpal bone. Were it not for the peculiar mode of its attachment to the pisiform 
 bone, it would have been inserted parallel to its lever ; whereas it is really inserted at 
 an angle of about 45°. It flexes the second row of the carpus upon the first, and this 
 upon the forearm ; at the same time it inchnes the hand towards its ulnar side. Its vio- 
 mentum, as well as that of the preceding muscle, occurs during semi-flexion of the hand 
 upon the forearm. 
 
 The Flexor Sublimis Digitorum. 
 
 Dissection. — ^The portion of this muscle, situated in the forearm, is exposed by cutting 
 across the middle, and turning aside the pronator teres, the flexor carpi radialis, and the 
 pahnaris longus, which form a superficial layer in front of it. With a little care, the ori- 
 gin of this muscle may be separated as far as the inner condyle of the humerus. In re- 
 moving the pronator teres, it is necessary to be extremely careful to avoid dividing the 
 radial origin of the flexor sublimis, which forms a very thin prolongation under the pro- 
 nator. The dissection of the palmar and digital portions of the mus- 
 cle is the same as that of the flexor profundus. 
 
 Divide the anterior annular ligament of the carpus vertically, and 
 remove the palmar fascia ; examine the disposition of this structure 
 opposite the heads of the metacarpal bones, and also the relations 
 of the tendons of the flexor sublimis and flexor profundus in the 
 palm of the hand ; then dissect the digital sheaths, which must be 
 divided in order to display the singular manner in which the ten- 
 dons of the flexor sublimis bifurcate and turn round, so as to em- 
 brace the corresponding tendons of the flexor profundus. 
 
 The flexor superficialis, sublimis, ox perforatus (e e,fig. 118 ; e,jig. 
 119), is a broad, flat, thick muscle, divided into four portions below. 
 It arises from the internal condyle or epitrochlea of the humerus, 
 and from the ulnar and radius, and is inserted into the second pha- 
 langes of the fingers. It arises from the epitrochlea by the common 
 tendon, from a rough surface on the fore part of the inner side of 
 the coronoid process of the ulna, and also from about two inches 
 of the radius. This latter origin consists of tendinous fibres attach- 
 ed to that obUque portion of the anterior border of the bone which 
 extends inward towards the bicipital tuberosity, and from which 
 arise the supinator brevis above, the flexor longus pollicis below, 
 and the muscle we are now describing in the middle. A great 
 number of fibres also arise from the broad aponeurotic septa which 
 divide this muscle from the flexor carpi ulnaris, and from the other 
 muscles of the superficial layer, viz., the pronator teres, the flexor 
 carpi radialis, and the palmaris longus. 
 
 From these diflferent origins the fleshy fibres proceed vertically 
 downward, forming a broad and thick belly, which is almost imme- 
 diately divided into four portions. These at first are in juxtaposi- 
 tion, but soon become arranged in two layers, like the tendons of 
 
 Fig. 119. 
 
252 
 
 MYOLOGY. 
 
 the extensor communis, viz., one anterior and larger, consisting of the divisions for the 
 median and ring fingers (the latter not being so strong as the former), and another pos- 
 terior, formed by the divisions for the index and little finger. Each division is, indeed, 
 a small muscle, having its own particular tendon, around which the fleshy fibres are ar- 
 ranged, at first regularly, and afterward on one side only : they are thus semi-penniform 
 muscles. The two posterior divisions are not so distinct as the anterior, and have a pe- 
 culiar arrangement : they generally constitute two small digastric muscles ; that is to 
 say, a fleshy belly terminates upon a flat tendon, which, becoming enlarged, gives origin, 
 in its turn, to a new fleshy belly. The four tendons, after emerging from the fleshy fibres, 
 pass together under the annular ligament {g) of the carpus, in conjunction with the me- 
 dian nerve, which lies on their outer side, and is often mistaken for a tendon, and with 
 the tendons of the flexor profundus digitorum and the flexor longus pollicis. This thick 
 bundle of tendons having reached the palm of the hand, is then distributed in a manner 
 to be noticed after the description of the flexor profundus, with the tendons of which 
 those of the flexor sublimis are intimately connected. 
 
 Relations. — It is covered by the pronator teres, the flexor carpi radialis, the palmaris 
 longus, the flexor carpi ulnaris, and the fascia of the forearm ; and it covers the flexor 
 profundus digitorum, from which it is separated by the ulnar vessels and nerves ; it also 
 covers the median nerve and the flexor longus pollicis, to- which it generally sends a 
 tendinous and fleshy prolongation. 
 
 The Flexor Profundus Digitorum. 
 
 Dissection. — This muscle is exposed by cutting across the flexor sublimis and the flex- 
 or carpi ulnaris. 
 The flexor profundus or perforans (i, fl.gs. 119, 120) is situated under the superficial flex- 
 Fig. 120. °^' which it exceeds in size, but resembles it in being divided below 
 
 into four portions. 
 
 Attachments. — It arises from the upper three fourths of the internal 
 and anterior surfaces of the ulna, from a well-marked cavity situated 
 on the inner side of the coronoid process behind the rough eminence 
 which gives attachment to the internal lateral ligament of the elbow, 
 from the inner two thirds of the interosseous ligament, from that part 
 of the fascia of the forearm which covers the inner surface of the ulna, 
 and, lastly, by a few fibres, from within and below the bicipital tuber- 
 osity of the radius. It is inserted into the front of the bases of the last 
 phalanges of the fingers ii,figs. 119, 120). 
 
 The fleshy fibres arise directly from these numerous origins, and 
 proceed vertically downward, the internal fibres alone being directed 
 somewhat obliquely forward and outward. The belly of the muscle 
 thus formed continues to increase in size, and is then divided into four 
 unequal portions, each constituting a semi-penniform muscle. These 
 four small muscles are in juxtaposition, and terminate in as many flat 
 tendons, which occupy the lower two thirds of the anterior surface of 
 the entire muscle, and are remarkable for being divided into very reg- 
 ular and closely-united parallel bands of a nearly white colour. The 
 four tendons emerging from the fleshy fibres at various heights, but 
 always above the anterior annular ligament of the carpus, pass under 
 this ligament conjointly with the tendons of the flexor sublimis, the 
 flexor pollicis longus, and the median nerve. In this situation they 
 are placed behind the tendons of the flexor sublimis, which are ar- 
 ranged in two layers, as we have already seen. The tendons of the 
 flexor profundus are always in juxtaposition, and, moreover, are united 
 together by means of dense cellular tissue and tendinous bands pass- 
 ing from one to the other : the fasciculus for the index finger alone remains distinct ; 
 and, therefore, the flexion of this finger is almost as independent of that of the others as 
 its extension, for which latter movement it receives a special muscle. Immediately below 
 the annular ligament the tendons separate from each other ; the two anterior tendons 
 of the flexor sublimis no longer cover the two posterior, but all four become situated in 
 front of the corresponding tendons of the flexor profundus, and arrive together at the 
 metacarpo-phalangal articulations : here they are received, at first, into a very strong 
 fibrous sheath, resulting from the division of the palmar fascia, and afterward into an- 
 other sheath {s,figs. 118, 119), which converts the groove in front of the phalanges into 
 a canal. If we divide any of these digital sheaths, we find the tendon of the superficial 
 flexor becoming flattened and hollowed underneath, as it were, into a groove, which is 
 exactly moulded upon the tendon of the deep flexor. About the middle of the first pha- 
 lanx the tendon of the sublimis ie,fl.g. 119) bifurcates, and gives passage to that of the 
 profundus, which it embraces by turning round it like the thread of a screw, and be- 
 coming posterior instead of anterior, as it was before. The two halves of the tendon 
 then reunite to form a groove having its concavity directed forward, and again separate 
 
THE LUMBEICALES AND THE FLEXOR LONGUS POLLICIS. '253 
 
 to be inserted into the rough edge of the groove on the second phalanx. The tendon of 
 the flexor profundus (i' i', figs. 119, 120), on the contrary, passes directly through the 
 sheath formed by that of the flexor sublimis, and is inserted into the third phalanx. The 
 tendons of the flexor profundus, moreover, present in their whole course very slightly 
 apparent traces of division. From the relation of the tendons of the two flexors to each 
 other, the superficial muscle has been called the perforatus, and the deep one the perforans. 
 
 Relations. — These should be examined in the forearm, in the palm of the hand, and 
 along the fingers. 
 
 In the forearm the flexor profundus is covered by the flexor sublimis, from which it is 
 separated by an incomplete tendinous septum, and by the median nerve. It covers the 
 ulna, the interosseous ligament, and the pronator quadratus ; it corresponds within to 
 the flexor carpi ulnaris, and without to the flexor longus pollicis. The ulnar vessels 
 and nerves are at first situated between this muscle and the flexor sublimis, and after- 
 ward separate it from the flexor carpi ulnaris. 
 
 In the palm its tendons are subjacent to those of the flexor sublimis, and cov^r the 
 interosseous muscles and the adductor pollicis. The lumbricales muscles take their 
 origin from them. 
 
 Along the fingers its tendons are in relation behind with the grooves of the phalanges, 
 and with the metacarpo-phalangal and phalangal articulations, and in front with the 
 tendons of the sublimis and the fibrous sheaths of the fingers. < 
 
 Action of the two Flexors. — These muscles flex the third phalanx upon the second, the 
 second on the first, this, again, upon the corresponding metacarpal bone, and, lastly, the 
 hand upon the forearm. The flexor sublimis has no action upon the third phalanges. 
 Its origin from the internal condyle of the humerus enables it to act upon the forearm, 
 and to assist in flexing it upon the arm. It is scarcely necessary to say that the bifur- 
 cation of the tendons of the flexor sublimis is intended to afford a sheath to, and bind 
 down, those of the flexor profundus. The flexor profundus flexes the third phalanx upon 
 the second, the second upon the first, the first upon the corresponding metacarpal bone, 
 and, lastly, the hand upon the forearm. 
 
 The Lumbricales. 
 
 The lumbricales (x,figs. 119, 120) are small fleshy tongues, which may be regarded as 
 accessories of the flexor profundus. They are four in number, distinguished as the first, 
 second, &c., counting from without inward. They extend from the tendons of the flexor 
 profundus to the first phalanges of three or four fingers. They arise from the tendons 
 after these have passed through the annular ligament : the first and the second in front 
 of the tendons for the index and middle fingers, the third in the interval between those 
 for the middle and ring fingers, and the fourth in the interval between those for the ring 
 and little fingers. From these origins they proceed, those near the median hue verti- 
 cally, and those at either side obliquely downward to the outer side of the metacarpo- 
 phalangal articulations of the corresponding fingers, where they terminate by a broad 
 tendinous expansion inserted into the edges of the extensor tendons, and completing the 
 sheath which those tendons form on the back of the first phalanges. The tendon of the 
 third lumbricalis appears to me to be almost always inserted, not into the outer side of 
 the ring finger, but into the inner side of the middle finger : an arrangement that cannot 
 well be accounted for. It is not uncommon to find this third lumbricalis bifurcated, and 
 attached, not only to the inner side of the middle, but to the outer side of the ring finger. 
 
 Relations. — They are placed between and upon the tendons of the flexor profundus, 
 and have, therefore, the same relations as those tendons in the palm of the hand ; they 
 are also in relation with the sides of the metacarpo-phalangal articulations, and the ten- 
 dons of the interosseous muscles. 
 
 Action. — It is difficult to determine their actions precisely. Vesalius has described 
 them as adductors, and Spigelius as flexors. I agree with Riolanus in regarding them 
 as specially intended to keep the extensor tendons closely applied to the phalanges, and 
 to serve instead of a proper sheath. They are of use also in binding together the ex- 
 tensor and flexor tendons, and preventing the displacement of either. 
 
 The Flexor Longus Pollicis. 
 
 Dissection. — ^The same as that of the flexor profundus. 
 
 The flexor longus pollicis {I, figs. 119, 120) is situated upon the same plane as the flex 
 or profundus digitorum, of which it may be considered a division ; it is thick, elongated, 
 and penniform. 
 
 Attachments. — It arises from the upper three fourths of the radius, from the contiguous 
 portion of the interosseous ligament, from the anterior border of the radius, and not un- 
 frequently by a prolongation, tendinous at its extremities and fleshy in the middle, from 
 the flexor sublimis digitorum. It is inserted into the upper end of the second phalanx 
 of the thumb. The fleshy fibres arise directly from these origins, pass vertically down- 
 ward, and are attached to the posterior surface of a flat tendon, which forms a continu- 
 ation of the series of tendons of the flexor profundus on the outside, and, like them, is 
 
254 MYOLOGY. 
 
 divided into bands. The fleshy fibres accompany the tendon as far as the anterior an- 
 nular hgament of the carpus ; it then passes beneath this ligament, is reflected over the 
 inside of the trapezium, and proceeds obhquely outward along the first metacarpal bone. 
 When it reaches the metacarpo-phalangal articulation of the thumb, it is received in an 
 osteo-fibrous sheath, resembling in every respect that of the tendons of the other fingers, 
 and, like them, is inserted in front of the upper extremity of the ungual phalanx of its 
 corresponding finger (Z, ^g-. 120). 
 
 Relations. — It is covered by the flexor sublimis, the flexor carpi radialis, the supinator 
 longus, and the radial artery ; it covers the radius and the interosseous ligament, from 
 which it is separated above by the interosseous vessels and nerves, and below by the 
 pronator quadratus. Its tendon is the most external of those which pass under the an- 
 terior annular ligament of the carpus, after leaving which it is received into a deep mus- 
 cular groove formed by the muscles of the ball of the thumb, and is ultimately enclosed 
 in its own osteo-fibrous sheath. 
 
 Action. — It flexes the last phalanx of the thumb upon the first, this upon the first met- 
 acarpal bone, and then the hand upon the forearm. In order to understand its action 
 precisely, we must suppose the muscular force to be concentrated upon the upper end of 
 the reflected portion ; it is then easy to see that it draws the phalanges inward, while 
 flexing them. It is, therefore, an opponens muscle. 
 
 The Pronator Quadratus. 
 
 Dissection. — Cut across all the tendons occupying the lower part of the anterior region 
 of the forearm, and this muscle will be exposed. 
 
 This small muscle (le petit pronateur, Bichat, m,figs. 119, 120) is situated at the low- 
 er part of the anterior region of the forearm, and forms the deepest layer of this region. 
 It is regularly quadrilateral, and thicker than at first sight it appears to be. 
 
 Attachments. — It arises firom the lower fourth of the internal border of the ulna, which 
 is directed so decidedly backward inferiorly, that the muscle is rolled round the bone ; 
 also, from an aponeurotic layer much thicker below than above, directed obliquely up- 
 ward and outward, and occupying the inner third of the muscle, upon which it terminates 
 in a number of elegant intersections ; lastly, from all that portion of the anterior surface 
 of the ulna upon which it lies. From these origins the fibres proceed horizontally out- 
 ward (le pronateur transverse, Winslow), becoming longer as they are more superficial, to 
 the lower fourth of the external border, anterior surface, and internal border of the radius. 
 
 Relations. — It is covered by the flexor profundus digitorum, the flexor longus poUicis, 
 the flexor carpi radialis, and the radial and ulnar arteries, and it partially covers the two 
 bones of the forearm and the interosseous ligament. 
 
 Action. — ^The pronator quadratus tends to approximate the two bones of the forearm ; 
 but as it is rolled around the ulna, which is immovable, it causes the radius to turn upon 
 that bone, and is therefore a pronator. Its action is much more energetic than would 
 at first sight appear : this depends on the number of its fleshy fibres, which are arranged 
 in several layers, the most superficial being the longest. 
 
 The Muscles of the External Region of the Forearm. 
 The muscles of this region are, the supinator longus, the extensores carpi radiales, 
 longior and brevior, and the supinator brevis. 
 
 The Supinator Longus. 
 
 Dissection. — The brachial portion of this muscle is exposed in the dissection of the 
 brachialis anticus and the triceps, and the portion situated in the forearm, by removing 
 the fascia from the outer and anterior aspect of the muscles of this region. 
 
 The 'supinator longus (/, Jigs. 118, 121), which is the most superficial muscle of the ex- 
 ternal and anterior aspect of the forearm, belongs both to the arm and the forearm (bra- 
 chio-radialis, Soemmering), and constitutes, in a great measure, the oblique ridge forming 
 the external boundary of the bend of the elbow. It is a long, flat muscle, fleshy in its 
 upper two thirds, and tendinous in its lower third. 
 
 Attachments. — It arises from the outer border of the humerus, and from the external 
 inter-muscular septum of the arm ; the extent of its humeral attachment varies from the 
 lower fourth to the lower third of that bone, and is limited above by the groove for the 
 musculo-spiral nerve. It is inserted into the base of the styloid process of the radius. 
 The fleshy fibres proceed from their origins downward, forward, and a little inward, to 
 form a fleshy belly, which is flattened from without inward, and is applied to the brachi- 
 alis anticus. After reaching the lower end of the humerus, the fleshy belly becomes 
 flattened from before backward, and passes vertically downward. At first it is thick, but, 
 during its progress, it expands, and becomes thin, until its fibres terminate successively 
 upon the anterior surface of an aponeurosis, which becomes entirely free from fleshy 
 fibres above the middle of the forearm, and is gradually contracted into a flat tendon, 
 that is inserted into the styloid process of the radius. 
 
 Relations. — It is covered bv the fascise of the arm and forearm : in the arm it is en- 
 
THE EXTENSORES CARPI EADIALES, LONGIOR ET BREVIOR. 255 
 
 closed in the same sheath with the brachialis anticus, from which it is separated by the 
 radial or musculo-spiral nerve ; in the forearm it has a sheath proper to itself: it is in 
 relation with the brachialis anticus, which is at first within, and afterward behind it ; 
 then with the extensor carpi radialis longior, the tendon of the biceps, the supinator bre- 
 vis, the pronator teres, the flexor carpi radialis, the flexor digitorum sublimis, the flexor 
 longus pollicis, the radial artery and veins, and the radial nerve. Its inner border limits 
 the bend of the elbow on the outside : the radial artery emerges from beneath this bor- 
 der, and then lies parallel to it. Its outer border is separated from the extensor carpi 
 radialis longior by cellular tissue, and, inferiorly, is in contact with the dorsal branch of 
 the radial nerve, which, at first, was situated beneath it. The most important of all 
 these relations is that with the radial artery, of which the long supinator may be consid- 
 ered the satellite muscle, and might be designated the muscle of the radial artery. 
 
 Action. — It might be asked, Why does the supinator longus form an exception to the 
 general rule, in being inserted into the lower end of the lever which it is intended to 
 move 1 for, while the forearm is in a state of supination, the axis of the muscle is verti- 
 cal, and its action appears limited to that of flexing the forearm ; but if the limb be pro- 
 nated, the direction of the muscle becomes oblique from without inward, and, therefore, 
 supination is the result of its contraction. After this effect has been produced, if the 
 muscle still continues to act, the forearm is flexed upon the arm. It is needless to state 
 that the distance of its insertion from the fulcrum gives the muscle great power, not- 
 withstanding its disadvantageous angle of incidence. 
 
 The Extensor Carpi Radialis Longior. 
 
 Dissection. — This muscle, as well as the succeeding one, will be exposed at the same 
 time as the supinator longus, beneath which it is placed. The lower end of its tendon 
 occupies the dorsum of the wrist, and should also be exposed. 
 
 The extensor carpi radialis longior (le premier ou long radial exteme ; radiahs externus 
 longior, Albinus, n,figs. 119, 121) is situated on the external and posterior aspect of the 
 forearm, below the supinator longus, of which it seems to be a continuation at its origin 
 from the humerus : like that muscle, it is flattened from within outward in the arm, and 
 from before backward in the forearm : it is fleshy in its upper third, and tendinous in its 
 lower two thirds. 
 
 Attachments. — It arises from the rough triangular impression terminating the external 
 border of the humerus, from the external inter-muscular septum, and from the anterior 
 surface of the common tendon. It is inserted into the back of the upper end of the sec- 
 ond metacarpal bone. The fleshy fibres arising directly from the parts mentioned con- 
 stitute a bundle, at first flattened on the sides, and forming a continuation of the supina- 
 tor longus, from which it is often difficult to separate it : it afterward becomes flattened 
 from before backward. The fibres pass vertically downward, and are attached to the 
 anterior surface of a tendon, a little beyond the upper third of the forearm. The tendon 
 then becomes narrower and thicker, proceeds along the outer border of the radius, pass- 
 es under the tendons of the abductor longus and extensor brevis pollicis, which cross it 
 obliquely, and turns a little outward, and then backward, to arrive at a groove common 
 to it and the extensor carpi radialis brevier ; it is then crossed at an acute angle by the 
 tendon of the extensor longus pollicis, and is finally inserted, by an expanded termina- 
 tion, into the second metacarpal bone {n',fig. 121). 
 
 Relations. — It is covered by the supinator longus and the fascia of the forearm ; on the 
 outside of the forearm, it is covered and crossed obliquely by the abductor longus and ex- 
 tensor brevis pollicis. and in the wrist by the tendon of the extensor longus pollicis. It 
 covers the elbow-joint, the extensor carpi radialis brevier, and the back of the wrist-joint. 
 
 The Extensor Carpi Radialis Brevior, 
 The extensor carpi radialis brevior (le second ou court radial exteme ; radialis externus 
 brevior, Albinus, o,figs. 119, 121, 122) is thicker, but shorter, than the preceding, below 
 which it is placed. It arises from the external condyle or epicondyle of the humerus, by 
 a tendon common to it and the extensor muscles of the fingers ; also, from a very strong 
 aponeurosis, situated upon its posterior surface ; and from another tendinous septum, 
 which divides it from the extensor communis digitorum. It is inserted into the back part 
 of the upper end of the third metacarpal bone. The fleshy fibres, thus arising from the 
 external condyle by means of an aponeurotic pyramid, are attached to the posterior sur- 
 face of a tendon, which becomes gradually narrower and thicker as it receives them. 
 The fibres themselves terminate about the middle of the forearm, and then the flat ten- 
 don passes backward into the same groove on the radius as that of the last-named mus- 
 cle, the two tendons being retained in it by the same fibrous sheath, and lubricated by 
 tne same synovial membranes, but separated from each other by a small vertical ridge 
 of bone. After leaving the common sheath, the tendon of the short separates from that 
 of the long radial extensor, passes still more posteriorly, and is inserted into the third 
 metacarpal bone (o', Tf^s. 121, 122). 
 
 RelatioDis. — It is covered by the preceding muscle, and, like it, is crossed obliquely on 
 
256 MYOLOGY. 
 
 the outside by the long abductor, the short, and then the long extensor muscles of the 
 thumb : it covers the external surface of the radius, from which it is separated by the 
 supinator brevis above, and the pronator teres in the middle. Its tendon covers and 
 protects the back of the wrist. In consequence of the different length of their fleshy 
 fibres, the supinator longus and the two radial extensors of the carpus are arranged one 
 above the other, the highest being the supinator longus, and the lowest the extensor 
 carpi radialis brevior. 
 
 Action of the two Radial Extensors. — These two muscles, which, from their insertions 
 might be called the posterior radials, extend the second row of the carpus upon the firs 
 and this upon the forearm ; they are also abductors of the hand, for they incline it to- 
 wards the radial side of the forearm. The extensor carpi radialis longior being attach- 
 ed to the humerus, can assist in flexing the forearm. 
 
 The Supinator Brevis. 
 
 Dissection. — Pronate the forearm forcibly. In order to expose this muscle completely, 
 divide the two radial extensors of the carpus, and even some of the muscles of the su- 
 perficial layer, on the back of the forearm. 
 
 The supinator brevis (p,figs. 119, 120, 122) is a broad muscle curved into the form of a 
 hollow cylinder, and rolled round the upper third of the radius : it forms by itself the deep 
 layer of the external region of the forearm. 
 
 Attachments. — It arises from the external lateral Ugament of the elbow, with which it 
 is blended, and by this means from the external condyle ; from the annular ligament of 
 the radius ; from the external border of the ulna, which is provided with a projecting 
 ridge for this purpose ; from a deep triangular excavation, in front of this ridge, arid below 
 the lesser sigmoid cavity of the ulna ; and, lastly, from the deep surface of an expansion of 
 its tendon of origin and the external lateral ligament, which covers the greater part of 
 the muscle. From these different origins {fig. 122) the fleshy fibres pass round the ra- 
 dius, into the posterior, external, and anterior surfaces of which bone they are inserted, 
 embracing in front the bicipital tubercle and the tendon of the biceps {figs. 119, 120). I 
 have seen a fleshy prolongation of this muscle, covering the anterior half of the annular 
 ligament of the radius, of which it might be regarded an extensor. 
 
 Relations. — The supinator brevis is covered by the radial extensors, the supinator lon- 
 gus, the pronator teres, the extensor communis digitorum, the extensor digiti minimi, 
 the extensor carpi ulnaris, the anconeus, and the radial artery and vein : it covers the 
 upper third of the radius, and also its annular ligament, the elbow-joint, and the inter- 
 osseous ligament. It is perforated by the deep branch of the radial nerve, which is dis- 
 tributed to all the muscles on the back of the forearm. 
 
 Action. — No muscle in the body is so completely rolled around the lever that it is in- 
 tended to move, for it forms five sixths of a cylinder ; it is, therefore, the chief agent in 
 supination, and the supinator longus can only be regarded as an accessory. 
 
 Muscles of the Posterior Region of the Forearm. 
 The muscles of the posterior region of the forearm constitute two very distinct layers : 
 one superficial, comprising the extensor communis digitorum, the extensor digiti minimi, 
 and the extensor carpi ulnaris ; the other deep, comprising the abductor pollicis longus, the 
 extensor brevis and extensor longus pollicis, and the extensor indicis 
 
 Muscles of the Superficial Layer. 
 
 One mode of dissection is common to all these muscles. Make a circular mcision 
 through the skin at the lower part of the arm ; pronate the arm, arifl make a perpendic- 
 ular incision from the external condyle of the humerus to the third metacarpal bone, 
 entirely dividing the sub-cutaneous cellular tissue down to the fascia ; remove this fascia 
 by careful dissection, except where it is very adherent. Trace the tendons of the ex- 
 tensor muscles along the back of the fingers. 
 
 The Extensor Communis Digitorum. 
 The extensor communis digitorum {b,fig. 121), situated at the back of the forearm, sim- 
 ple above and divided into four portions below, arises from the external condyle of the 
 humerus, and is inserted into the second and third phalanges of the four fingers. Its ori- 
 gin consists of a tendon common to it, and to the extensor carpi radialis brevior, exten- 
 sor digiti minimi, and extensor carpi ulnaris. This tendon consists of a four-sided pjrra- 
 raid, and is formed by the fascia of the forearm, by a lamina separating this muscle from 
 the extensor carpi radialis longior, by another lamina separating it from the extensor 
 digiti minimi and the extensor carpi ulnaris, and, lastly, by another situated between it 
 and the supinator brevis. The fleshy fibres arising from the interior of this pyramid form 
 at first a thin, but afterward a much larger muscle, which becomes flattened from before 
 backward, and soon divides into four fasciculi. The two middle fasciculi, intended for 
 the middle and the ring fingers, are stronger than those destined for the index and little 
 fingers, i. e., the two extreme fasciculi, which, lower down, become placed in front of 
 
THE EXTENSOR DIGITI MINIMI. 
 
 257 
 
 the middle fasciculi. In this manner they all pass under the dor- Fig. 191. 
 
 sal ligament (r,fig. 121) of the carpus in a proper sheath. After 
 leaving this sheath, in which they are provided with a synovial 
 capsule,* extending both above and below the dorsal ligament, the 
 four tendons become situated on the same plane, and diverge from 
 each other ; the two middle tendons proceed along the backs of the 
 corresponding metacarpal bones ; the external and internal ten- 
 dons {b' h',Jig. 121) correspond to the interosseous spaces, which 
 they cross obliquely, in order to assume a position behind the heads 
 of the metacarpal bones, to which they belong. Having reached 
 the metacarpo-phalangal articulations, the tendons become nar- 
 rower and thickened, and give oif on each side a fibrous expansion, 
 attached to the sides of the joint ; they then enlarge again so as to 
 cover the dorsal surface of the first phalanges, receive and are re- 
 enforced by the tendons of the lumbricales, and opposite the ar- 
 ticulation of the first with the second phalanx, they divide into 
 three portions, one median, which is implanted upon the upper end 
 of the second phalanx, and two lateral, which pass 2dong the sides 
 of the second phalanx, approach each other at the lower half of the 
 dorsal surface of the second phalanx, unite by their neighbouring 
 edges, and are inserted into the upper end of the third phalanx. 
 Opposite the metacarpal bones they sometimes split into two or 
 three small juxtaposed tendons, and at the lower end of these 
 bones the tendons for the little, ring, and middle fingers commu- 
 nicate with each other by expansions of variable size, and some- 
 times by a true bifurcation (see fig. 121). The tendon for the in- 
 dex finger is alone free. The communication of the tendon of the 
 little with that of the ring finger takes place opposite the metacar- 
 po-phalangal articulation, by means of a transverse band, which 
 forms a projection under the skin. Lastly, we not unconmionly 
 see a tendinous prolongation arising from the anterior surface of these tendons, and in- 
 serted into the upper end of the first phalanx. 
 
 Relations. — The extensor communis digitorum is covered by the fascia of the forearm, 
 from which a great number of its fibres arise superiorly, by the dorsal ligament of the 
 carpus and the dorsal fascia of the metacarpus, which separate it from the skin : it cov- 
 ers the supinator brevis, the three long muscles of the thumb, the extensor proprius in- 
 dicis, the lower radio-cubital articulation, the carpus, the metacarpus, and the fingers. 
 
 Action. — ^This muscle extends the third phalanx upon the second, the second upon the 
 first, the first upon the corresponding metcarpal bone, then the carpus, and, lastly, the 
 radio-cubital articulation. It is necessary for me to mention the independence of the 
 muscular fasciculi proceeding to each finger : this is peculiar to man, and is much more 
 remarkable in some individuals than in others. By continual exercise, the faculty of 
 extending one finger without the others may be acquired. The tendon for the index is 
 generally the only one not united to the others, and therefore the movements of this 
 finger are by far the most independent. 
 
 The Extensor Digiti Minimi. 
 
 This is a very slender muscle (extensor proprius auricularis, Albinus, c, fig. 121) placed 
 on the inner side of the common extensor, to which it appears to be an appendix. It is 
 difficult to trace its origin as far as the common tendon, with which it is connected only 
 by an aponeurotic prolongation. Its fleshy fibres arise from this prolongation, and from 
 a fibrous pyramid which separates it from the muscles of the deep layer, from the exten- 
 sor communis digitorum externally, and internally from the extensor carpi ulnaris, and 
 is completed superficially by the fascia of the forearm. The fibres constitute a small, 
 fusiform, fleshy belly, which accompanies the tendon (at least on one side) as far as the 
 head of the ulna ; there the tendon enters a special fibrous sheath formed behind the 
 head of that bone ; it is then reflected inward to the fifth metacarpal bone, behind which 
 it is retained in a thinner sheath, which, like the preceding, is lined by a synovial mem- 
 brane. t The tendon then spUts into two bands, of which the external (or radial) re- 
 ceives the inner bifurcation of the extensor communis. The three tendinous prolonga- 
 tions becoming united, envelop, as in a sheath, the dorsal aspect of the first phalanx of 
 this finger ; having reached the articulation of the first with the second phalanx, they 
 divide into three portions, which are attached precisely in the same manner as the ten- 
 dons of the extensor communis. 
 
 Action. — As its name indicates, this muscle extends the little finger. It might at first 
 sight be imagined that this finger might be moved independently, since it receives a sep- 
 arate muscle ; but the connexion of its tendon with that of the extensor communis ren- 
 
 See note, p. 296. 
 
 Kk 
 
 t See note, p. 296. 
 
t,58 MYOLOGY. 
 
 ders any such independent action as difficult as in the other fingers, and much more so 
 than in the index finger. 
 
 The Extensor Carpi Ulnaris. 
 
 The extensor carpi ulnaris (c, fig. 121), the most superficial and the most internal* of the 
 muscles on the back of the forearm, arises from the external tuberosity of the humerus ; 
 from the posterior surface of the ulna, which is a little excavated for this purpose ; from 
 the middle third of the posterior border of that bone ; and from the anterior surface of 
 an aponeurosis covering the muscle behind. It is inserted behind the upper end of the 
 fifth metacarpal bone. Its origin is effected by means of a fibrous pyramid, the apex of 
 which is attached to the outer tuberosity of the humerus. From the interior of this pyr- 
 amid, and from the other origins above mentioned, the fleshy fibres proceed to a tendon, 
 which, by a very uncommon arrangement, extends through the substance of the muscle, 
 even from its superior attachment, without commencing in the form of an aponeurosis. 
 At the lower third of the forearm, this tendon appears on the posterior border of the then 
 semi-penniform muscle, and continues to receive fleshy fibres on its anterior edge until 
 it enters the groove intended for it on the ulna. This oblique groove is continued as far 
 Fig. 182. as the insertion of the tendon into the metacarpal bone, by means of a 
 
 long, fibrous sheath, and is lined throughout by a synovial membrane. 
 Relations. — The extensor carpi ulnaris is covered by the fascia of 
 the forearm : it covers the ulna, the supinator brevis, and the mus- 
 cles of the deep layer. 
 
 Action. — It extends the second row of the carpus upon the first, and 
 this upon the forearm. It is, at the same time, an adductor of the 
 _g hand, which it inclines towards the ulnar border of the forearm. 
 
 The Anconeus. 
 
 The anconeus (brevis anconeus, Eustachius ; le petit ancone, Wins- 
 low, ff, figs. 121, 122) is a short, triangular muscle, so named from 
 its situation {uyKuv, the prominence of the elbow). It appears to be 
 a continuation of the external portion of the triceps, from which it is 
 only separated by a very slight cellular interval. 
 
 Attachments. — It arises from the back part of the outer tuberosity 
 of the humerus, and is inserted into the outer side of the olecranon, 
 and a triangular surface bounded internally by the posterior border of 
 the ulna. Its origin from the condyle consists of a tendon quite dis- 
 tinct from that common to the muscles on the back part of the fore- 
 arm. This tendon splits into two diverging bands. The fleshy fibres 
 arising from these proceed inward, the upper horizontally, the lower 
 obliquely downward, and are inserted directly into the outer side of 
 the olecranon, so as to be continuous with the triceps, and into the 
 surface of the ulna. 
 
 Relations. — It is covered by a prolongation from the fascia of the 
 triceps, and it covers the radio-humeral articulation, the annular lig- 
 ament of the radius, the ulna, and a small portion of the supinator 
 brevis. 
 
 Action. — ^It extends the forearm upon the arm, and vice versa ; from its oblique direc- 
 tion, it can also rotate it inward. 
 
 Muscles of the Deep Layer. 
 Dissection. — This is the same for all the muscles of the deep layer of the forearm, and 
 consists in removing the muscles of the superficial layer, especially the extensor com- 
 munis digitorum and the extensor digiti minimi. 
 
 The Mductor Longus Pollicis. 
 
 The abductor longus pollicis (extensor ossis metacarpi pollicis, i,figs. 121, 122) is the 
 broadest, thickest, and most external muscle of the deep layer (le grand abducteur, Bichat). 
 
 Attachments. — It arises from the ulna below the origin of the supinator brevis, from 
 the interosseous hgament, from the radius, and from a tendinous septum between it and 
 the extensor longus pollicis. It is inserted into the upper end of the first metacarpal 
 bone. From the above-mentioned origins the fleshy fibres proceed obUquely downward 
 and outward, constitute a flattened fusiform belly, and are successively attached to the 
 posterior surface of an aponeurosis, which becomes condensed into a flat tendon ; this 
 tendon turns round the radius, crossing over the radial extensors of the carpus, and, at 
 the same time, ceasing to receive any fleshy fibres ; it is then received into the outer 
 groove on the lower end of the radius, conjointly with the tendon of the extensor brevis 
 
 * It is needless to remark that this internal situation presupposes the supination of the forearm. In prona- 
 tion, this muscle may be correctly termed ulnaris externus, and le cubital externe, according to Albinus and 
 Witulow. 
 
THE EXTENSOR BREVIS POLMCIS, ETC. 254 
 
 pollicis, a small fibrous septum intervening between them, and, finally, is inserted into 
 the first metacarpal bone. This tendon is almost always divided longitudinally into two 
 equal parts, and not unfrequently the division extends up to the fleshy portion. Of these 
 two divisions, one is inserted into the first metacarpal bone, the other furnishes attach- 
 ments to the abductor brevis pollicis. 
 
 Relations. — It is covered by the extensor communis digitorum and extensor digiti min- 
 imi : it lies immediately under the fascia, from the outer side of the radius to its termi- 
 nation. It covers the interosseous ligament, the radius, the tendons of the radial exten- 
 sors of the carpus, and the outer side of the wrist-joint, where it may be easily distin- 
 guished under the skin. 
 
 Action. — It extends and abducts the first metacarpal bone : for a long time it was 
 called the extensor of the thumb ; but its chief use is, as Albinus first remarked, in ab- 
 duction. Winslow observes that, from its obliquity, it can act as a supinator ; lastly, it 
 assists in extending the hand. 
 
 The Extensor Brevis Pollicis. 
 
 This muscle (extensor primi intemodii pollicis, I, figs. 121, 122) is situated internally 
 to the preceding, which it exactly resembles- in figure and direction, and with which it 
 was for a long time confounded (partie du premier extenseur du pouce, Winslow). It is, 
 however, shorter and mpre slender (petit extenseur du pouce, Bichat). 
 
 It arises from the radius, occasionally from the ulna, and from the interosseous liga- 
 ment ; and is inserted into the upper end of the first phalanx of the thumb. Its origin 
 consists of short, tendinous fibres, the fleshy fibres proceeding from which constitute a 
 slender fasciculus, having a similar arrangement to that of the preceding muscle ; its 
 tendon is received into the same fibrous sheath, but is divided from the other by a small 
 septum, and passes on, to be inserted into the first phalanx. 
 
 Relations. — The same as those of the abductor longus. 
 
 Action. — It extends the first phalanx upon the first metacarpzil bone, and then becomes 
 an abductor and extensor of the metacarpal bone of the thumb. 
 
 The Extensor Longus Pollicis. 
 
 This muscle (extensor secundi internodii pollicis, m,figs. 121, 122) is much larger than 
 the extensor brevis, within and parallel to which it is situated. It arises from a consid- 
 erable extent of the ulna, from the interosseous ligament, and from the tendinous septa, 
 dividing it from the extensor carpi ulnaris, and the extensor proprius indicis : it is insert- 
 ed into the upper end of the second phalanx of the thumb. The fleshy fibres form a flat 
 fusiform bundle, directed obliquely like the preceding muscle ; they terminate in succes- 
 sion around a tendon, which emerges from them at the carpal extremity of the ulna, en- 
 ters a special osteo-fibrous sheath, and crosses obliquely over the tendons of the two ra- 
 dial extensors, being separated from the tendons of the abductor longus and extensor 
 brevis pollicis by an intervjil which may be readily distinguished through the integu- 
 ments, and gives rise to the hollow on the outer side of the wrist, commonly called the 
 salt-cellar. The tendon next crosses obliquely over the first interosseous space, gains the 
 inner edge of the first metacarpal bone, and then that of the first phalanx, upon which it is 
 expanded, and proceeds to be inserted into the second or ungual phalanx of the thumb. 
 
 Relations. — Its general relations are the same as those of the preceding muscle. 
 
 Action. — Its uses are also the same ; but it acts in a special manner upon the second 
 phalanx of the thumb, which it extends upon the first before exerting any influence upon 
 this last-mentioned bone. It has less power in abduction than the preceding muscles. 
 
 The Extensor Proprius Indicis. 
 
 This is an elongated fusiform muscle (indicator, Albinus, r, fig. 122) like the preceding, 
 below and parallel to which it is situated. It arises from the ulna, the interosseous liga 
 ment, and a septum intervening between it and the extensor longus pollicis : it is insert- 
 ed into the last two phalanges of the index finger. The fleshy fibres proceed obliquely 
 from their origins and terminate around a tendon, which they accompany as far as the 
 sheath of the extensor communis digitorum : into this sheath the tendOn enters, and. 
 having escaped from it, crosses obliquely over the carpus and the second interosseous 
 space, becomes situated on the inside of the tendon given off to the index finger by the 
 extensor conununis, unites intimately with that tendon opposite the lower end of the 
 metacarpus, and terminates with it in the manner already indicated. Its relations are 
 the same as those of the preceding muscles. 
 
 Action. — It enables the index finger to be extended independently of the others, and 
 hence, without doubt, arises the particular use of that finger. I should add, that the union 
 of its tendon with the one furnished by the common extensor is so intimate, that its in- 
 dependence of action would have been much less, had not the fleshy fasciculus of the 
 common extensor destined for it been itself almost isolated. 
 
260 MYOLOGY. 
 
 MUSCLES OF THE HAND. 
 
 Tlie AbdiMor Brevis Pollicis. — Opponejis Pollicis. — Flexor Brevis Pollicis. — Adductor Pol- 
 lids. — Palmaris Brevis. — Abductor Digiti Minimi. — Flexor Brevis Digiti Minimi. — Op- 
 ponens Digiti Minimi. — The Interosseous Muscles, Dorsal and Palmar. 
 
 The muscles of the hand occupy the entire palmar region. They are divided into 
 those situated on the outer side, viz., the muscles of the thenar eminence, or ball of the 
 thumb ; those on the inner side, viz., the muscles of the hypothenar eminence, or of the 
 little finger ; and those which occupy the interosseous spaces. 
 
 All the muscles of the thenar eminence belong to the thumb ; they are, in the order 
 of their superposition, the abductor brevis, the opponens, the flexor brevis, and the ad- 
 ductor pollicis. Those of the hypothenar eminence all belong to the little finger, and 
 are the abductor, the flexor brevis, and the opponens. The palmaris brevis may be in- 
 cluded in this region. 
 
 The interosseous muscles are seven in number — four dorsal and three palmar. The 
 lumbricales, vi^hich belong to this region, have been already described with the tendons 
 of the flexors of the fingers. 
 
 Muscles of the Thenar Eminence, or Muscles belonging to the Thumb 
 
 I divide these into three muscles inserted into the outer side of the first phalanx of 
 the thumb, or into the first metacarpal bone, and a single muscle inserted into the inner 
 side. The former are the abductor brevis, the opponens, and the flexor brevis ; the lat- 
 ter consists of the adductor, in which I include a part of the flexor brevis of authors 
 generally. 
 
 Muscles inserted into the Outer Side of the First Phalanx of the Thumb, or 
 into the First Metacarpal Bone. 
 
 Dissection. — Make an oblique incision from the middle of the annular ligament of the 
 carpus to the outer side of the first phalanx of the thumb, and a circular incision round 
 the wrist ; detach the flaps, raise the external and middle palmar fasciae, and then cau- 
 tiously separate the muscles of this region, which are recognised by the following char- 
 acters. 
 
 The Abductor Brevis Pollicis. 
 
 This is the most superficial of the muscles constituting the ball of the thumb {q, fig. 
 119). It arises by tendinous and fleshy fibres from the os scaphoides, from the upper, 
 anterior, and external part of the anterior annular ligament of the carpus, and almost 
 always from an expansion of the tendon of the abductor longus pollicis. It is a small, 
 •hin, flat muscle, passing outward and downward, and inserted by a flat tendon into the 
 outer side of the first phalanx of the thumb. A very narrow cellular line separates it on 
 the inside from the flexor brevis, which is situated on the same plane. It is covered by 
 the external palmar fascia, and it covers the opponens muscle, from which it is distin- 
 guished by the direction of its fibres, and by a thin intervening aponeurosis. 
 
 Action. — It draws the thumb forward and inward, and therefore might be termed the 
 superficial opponens. From its attachments, it might be called scaphoido-phalangal. 
 
 The Opponens Pollicis. 
 
 The opponens pollicis (r, figs. 119, 120), a small triangular muscle, arises from the trape- 
 zium, and the anterior and external part of the anterior annular ligament of the carpus, 
 in front of the sheath of the flexor carpi radialis. From these origins, which are partly 
 fleshy and partly tendinous, the fleshy fibres radiate downward and outward, the highest 
 being the shortest and the most horizontal. They are inserted into the entire length of 
 the outer border of the first metacarpal bone. 
 
 This muscle is covered by the abductor brevis, which projects a little beyond it on the 
 outside, and from which it is separated by a more or less distinct aponeurosis. It cov- 
 ers the first metacarpal bone, and its articulation with the trapezium. 
 
 Action. — It draws the first metacarpal bone inward and forward, thus opposing it to the 
 others, as its name indicates. From its attachments, it may be called trapezio-metacarpal. 
 
 The Flexor Brevis Pollicis. 
 It is difficult to point out the limits of this muscle, or, rather, they have hitherto been 
 quite arbitrary. Its inferior attachment has been usually divided between the external 
 and the internal sesamoid bones (Boyer, Traitl d' Anatomic, torn, ii., p. 307 ; Bichat, Ana- 
 tomic Descriptive, torn, ii., p. 272) ; but we shall consider that portion only whioli is at- 
 tached to the external sesamoid bone as belonging to this muscle, referring tlie entire 
 fleshy mass that is inserted into the internal sesamoid bone to the adductor pollicis.* 
 
 ' The arrangement I have adopted is founded upon the inferior attachments of the musr les, for at their 
 origins they are so blended that their division is more or less arbitrary. I divide the muscular fasciculi con- 
 nected witu the thumb, therefore, into two sets, viz., those proceeding from the carpus to tlie first metacan>al 
 
THE ADDUCTOR P0LLICI8, ETC. 26^1 
 
 This division is, moreover, established by the tendon (I, fig. 120) of the flexor longns 
 pollicis. Proceeding then from below upward, in the dissection of the flexor brevis {t. 
 iigs. 119, 120), we shall see that it is triangular, much larger than the preceding two 
 muscles, bifid above, and channelled in front. It arises by tendinous and fleshy fibres 
 from a process on the trapezium, from the lower edge of the annular ligament, from all 
 the reflected portion of that ligament forming the sheath of the flexor carpi radialis, and 
 extending as far as the os magnum, and from the os magnum itself by a portion which 
 is usually distinct. From these different origins the fleshy fibres proceed downward and 
 outward, the intem£d being the most oblique ; and, converging so as to form a thick fas- 
 ciculus, are inserted, through the medium of the external sesamoid bone, into the first 
 phalanx. 
 
 Relations. — It is covered by the external pahnar fascia, which is prolonged in front of it : 
 it covers the tendon of the flexor longus pollicis, and more internally those of the common 
 flexor. It also covers a small portion of the outer border of the adductor pollicis, and 
 the tendon of the flexor carpi radialis. Its outer border, or, rather, side, is in relation 
 with the short abductor, from which it is easily separated, and with the opponens, some- 
 times being continuous with it. Its inner border is distinct from the adductor below, 
 but is confounded with it at its origin. Its tendon of insertion into the phalanx is cov- 
 ered by that of the short abductor, which lies externally to it. From its attachments, it 
 might be called trapezio-phalangal, and, from its uses and position, the opponens internus. 
 
 Action. — It is evidently not a flexor pollicis, but, like the preceding muscles, it draws 
 the thumb forward and inward, and it acts more decidedly in producing the latter effect. 
 because it is inserted in a more favourable manner than the other muscles. This, there- 
 fore, is also an opponens muscle. 
 
 Muscle inserted into the Inner Side of the First Phalanx of the Thumb. 
 The Adductor Pollicis. 
 
 This is the largest of all the muscles of the thumb (m, figs. 119, 120) ; it is very ir- 
 regularly triangular, and arises from the entire extent of the anterior border of the third 
 metacarpal bone, from the anterior surface of the os magnum, from the anterior and up- 
 per part of the trapezoides, from the anterior part of the trapezium by a tendinous and 
 fleshy fasciculus, and from the palmar interosseous fascia, near the third metacarpal 
 bone. From these different origins the fleshy fibres proceed, the lower horizontally, the 
 rest more and more obliquely outward ; they all converge to form a thick fleshy bundle, 
 which is inserted through the medium of the internal sesamoid bone into the first pha- 
 lanx of the thumb. 
 
 Relations. — Its inner two thirds are deeply situated, and covered by the tendons of the 
 flexor profundus digitorum, by the lumhricales, and by an aponeurosis, which, becoming 
 continuous with the deep interosseous fascia, constitutes the sheath of the muscle. It 
 is sub-cutaneous near its lower border. It covers the first two interosseous spaces, from 
 which it is separated by a very strong aponeurosis. It is again sub-cutaneous behind, 
 also along its lower border, which may be easily felt under the fold of skin, extending 
 from the thimib to the index finger. 
 
 Action. — It is an adductor ; it draws the thumb towards the median line or axis of tho 
 hand, represented by the third metacarpal bone. 
 
 Muscles of the Hypothenar Eminence, or Muscles belonging to the Little Finger. 
 
 These muscles correspond exactly to those of the thumb : the reason that three only 
 are described is, that the one which represents the adductor of the thumb is situated in 
 the fourth interosseous space, and is, therefore, classed with the interosseous muscles, 
 to be hereafter described. All the muscles of the hypothenar eminence are inserted into 
 the inner side of the first phalairx of the little finger, or into the third metacarpal bone 
 We find also a cutaneous muscle in this region, viz., the palmaris brevis. 
 
 The Palmaris Brevis. 
 
 This is a very thin square muscle (caro quaedam quadrata, J, fig. 1 18), situated in the 
 adipose tissue covering the hypothenar eminence. It arises from the anterior annular 
 ligament of the carpus, and the inner edge of the middle palmar fascia, by very distinct 
 tendinous fasciculi, succeeded by equally distinct fleshy bundles, which pass horizontally 
 inward, and terminate in the skin. 
 
 Relations. — It is covered by the skin, to which it adheres intimately, especially by its 
 inner extremity (le pahnaire cutane, Winslow ) ; it covers the muscles of the hypothenar 
 
 bone and to the outer side of the first phalanx of the thumb, and those extending from the carpus to the inner 
 side of the same phalanx. The first set, which might be regarded as a single muscle, comprises the abductor 
 brevis, the opponens, and the flexor brevis ; the other constitutes the abductor pollicis, which I regard as the 
 first palmar interosseous muscle. The action of the first set is common, viz., to carry the thumb forward and 
 inward ; they are, therefore, all muscles of opposition (perhaps no muscles are so badly named as those of the 
 thenar eminence) ; the muscle formeJ !jy the second set is really an adductor, as its name implies, and so are 
 all the palmar interossci. ;im0Qg .., a :i it ^l (Uld be included. 
 
262 MYOLOGY. 
 
 eminence and the ulnar artery and nerve, from all of which it is separated by the inter- 
 nal palmar fascia. 
 Action. — It corrugates the skin over the hypothenar eminence. 
 
 The Abductor Digiti Minimi. 
 
 It arises from the pisiform bone, and from an expansion of the flexor carpi ulnans, 
 by tendinous fibres ; these are succeeded by a fusiform fleshy belly {v,fig. 119), which 
 passes vertically along the internal (or ulnar) surface of the fifth metacarpal bone, and is 
 inserted by a flat tendon into the inner side of the first phalanx of the little finger. 
 
 Relations. — It is covered by the external palmar fascia, and covers the opponens digiti 
 minimi. 
 
 Action. — As it name denotes, it abducts the little finger from the axis of the hand. 
 
 The Flexor Brevis Digiti Minimi. 
 
 This muscle {w,fig. 119) is situated on the outer or radial border of the precedmg, 
 from which it is distinguished by arising from the unciform bone. ■ The two muscles are 
 separated by the ulnar vessels and nerves, which pass between them, in order to penetrate 
 into the deep palmar region. In other respects, as in direction, insertions, and relations, 
 the muscles resemble each other ; they have accordingly been described by Chaussier as 
 a single muscle, under the name of Ze carpo-phalangien du petit doigt. This muscle is often 
 wanting, but the fleshy fibres which usuaUy constitute it are then always found in some 
 measure blended with the other muscles. 
 
 Action. — It produces slight flexion of the little finger. 
 
 The Opponens Digiti Minimi. 
 
 This muscle {y,fig. 119) is generally distinct from the preceding, and is the represent- 
 ative of the opponens pollicis. It arises from the hooklike process of the unciform bone, 
 and from the contiguous part of the annular ligament : from these points the fibres pro- 
 ceed downward and inward (i. e., towards the ulnar border of the hand), the highest be- 
 ing the shortest and the most horizontal : they are i-nserted into the whole length of the 
 inner or ulnar margin of the fifth metacarpal bone. 
 
 Relations. — It is covered by the preceding muscles and by the internal palmar fascia : 
 it covers the fifth metacarpal bone, the corresponding interosseous muscle, and the ten- 
 don of the superficial flexor proceeding to the little finger. 
 
 Action. — It opposes the little finger to the thumb by drawing it forward and outward. 
 
 The Interosseous Muscles. 
 
 Dissection. — Remove the tendons of the extensor muscles behind, and those of the flexor 
 muscles in front, together with the lumbricales, preserving, at the same time, the digital 
 inseiiions of these small muscles. Dissect and study the deep palmar fascia, a fibrous 
 layer covering the interosseous muscles in the palm of the hand, which sends prolonga- 
 tions between the two kinds of these muscles, and is inserted into the anterior borders 
 of the metacarpal bones, enclosing each interosseous muscle in a proper sheath. After 
 having studied the palmar and dorsal fascia, separate the bones of the metacarpus by 
 tearing their connecting ligaments, and the interossei will then be completely exposed. 
 
 The interossei, so named from their position, and distmguished from each other by the 
 numerical appellations first, second, third, &c., are divided into palmar (p p p, Jig. 123) 
 and dorsal {ddd d), according as they are situated nearer to the palm or to the back of 
 the hand. They are also distinguished into adductors and abductors of the fingers. 
 
 There are two in each interosseous space, one occupying its dorsal, the other its pal- 
 mar aspect ; and, as there are four interosseous spaces, it would seem that there should 
 be eight interosseous muscles ; nevertheless, seven only are admitted by modern anat- 
 omists, in consequence of the first palmar interosseous muscle, which belongs to the 
 thumb, being separately described as the adductor pollicis. This separation is founded 
 upon the peculiar arrangement presented by that muscle, which is not attached from the 
 first to the second, but extends from the first to the third metacarpal bone ; an importjuit 
 fact, that explains the great extent to which the thumb can be adducted. 
 
 A minute description of the interosseous muscles would be both useless and tedious. 
 I shall content myself with pointing out their genereil conformation, and the law which 
 regulates their arrangement. 
 
 In taking a general view of the interosseous muscles, they must be considered with 
 regard to the adduction or abduction of the fingers ; but these terms must not be under- 
 stood in reference to the axis of the skeleton, but to the axis of the hand, which is rep- 
 resented by a line passing through the third metacarpal bone and the middle finger. This 
 being admitted, all the dorsal interossei will be found to be abductors, and all the palmar 
 interossei adductors. 
 
 Thus, the first dorsal interosseous muscle proceeds from the first and second meta- 
 carpal bones to the outer or radial side of the first phalanx of the index finger : it is there- 
 fore an abductor of that finger. The second extends ft-om the second and third meta- 
 
THE DORSAL INTEROSSEI. 263 
 
 carpal bones to the outer or radial side of the first phalanx of the middle finger, and is an 
 abductor of that finger. The third extends from the third and fourth metacarpal bones 
 to the inner or ulnar side of the phalanx of the middle fingers, and is also 
 an abductor of the same, because it separates it firom the supposed axis of 
 the hand. The fourth extends from the fourth and fifth metacarpal bones 
 to the inner or ulnar side of the first phalanx of the fourth finger, and it again 
 is an abductor of that finger from the axis of the hand, although, as well as 
 the preceding muscle, it is an adductor as regards the axis of the body. In 
 order to render this view more intelligible, I have been accustomed to rep- 
 resent the five fingers by five lines (see diagram d), to prolong the middle 
 line for the axis of the hand, and then to draw other lines (the four fine lines) 
 representing the axes of the muscles ; the demonstration is thus rendered 
 complete. 
 
 In the same manner, all the palmar interossei are adductors as regards the axis of the 
 hand. Thus the first, which is represented by the adductor pollicis, and extends from 
 the third metacarpal bone to the inner or ulnar side of the first phalanx of the thumb, is 
 an adductor as regards the axis of the hand as well as that of the body ; the second, ex- 
 tending from the second metacarpal bone to the inner or ulnar side of the first phalanx 
 of the index finger, is an adductor both as regards the axis of the hand and that of the 
 body ; the third, extending from the fourth metacarpal bone to the outer or radial side 
 of the first phalanx of the ring finger, is an adductor as regards the axis of 
 the hand ; and, lastly, the fourth, extending from the fifth metacarpal bone to 
 the outer or radial side of the first phalanx of the little finger, is an adductor 
 as regards the axis of the hand, but an abductor in reference to the axis of 
 the body. A similarly-constructed figure, as that employed for the dorsal 
 interossei, wiU always keep this arrangement in the memory (see diagram 
 p ; the four fine lines represent the axes of the pahnar muscles). The gen- 
 eral disposition of the interossei may be summed up in the following very 
 simple law : All the dorsal interossei have their fixed attachments farther 
 from the axis of the hand than their movable one ; all the palmar interossei 
 have their fixed attaclmients nearer to the axis of the hand than their movable one. 
 
 We may now consider the general arrangement of these little muscles. 
 
 The Dorsal Interossei. 
 
 These are short, prismatic, and triangular muscles (d to d. Jig. 123), extending from 
 the two metacarpal bones, between which they are placed, to fHg. 123. 
 
 the first phalanx and the extensor tendon of one of the corre- 
 spending fingers. They arise by a double origin, between 
 which the perforating arteries pass. But while one of these 
 origins is limited to the back part of the lateral surface of one 
 of the metacarpal bones, the other occupies the whole length 
 of the corresponding lateral surface of the other metacarpEd 
 bone. From this double origin the fleshy fibres pass obliquely 
 forward round a tendon, which only emerges from them near 
 the metacarpo-phalangal articulation ; it then expands, and is 
 inserted partly to the upper end of the first phalanx and partly 
 to the outer edge of the corresponding extensor tendon. 
 
 Relations. — The dorsal interossei correspond behind with the 
 dorsal surface of the hand and the extensor tendons, from which they are separated by 
 a very thin aponeurosis ; in front, they are visible in the palm of the hand by the sides of 
 the palmar interossei, and, like the latter, are covered by the muscles and tendons of the 
 palmar region, being separated from those parts by the deep pahnar fascia. A distinct 
 cellular line, or, rather, an aponeurotic septum, intervenes between one of their lateral 
 surfaces and the corresponding palmar interosseous muscle ; the other lateral surface is 
 in relation, through its entire length, with the metacarpal bone on which it is implanted. 
 
 Action. — These muscles are evidently abductors of the first phalanges of the fingers, 
 the axis of the hand being taken as the point of departure. Their insertion into the ex- 
 tensor tendons explains why previous extension of the fingers is necessary to the move- 
 ment of abduction. 
 
 The first dorsal interosseous muscle merits a special description. It is larger than the 
 others, on account of the greater size of the space occupied by it ; it is flat and triangu- 
 lar, and arises by two origins, separated, not by a perforating branch, but by the radial 
 artery itself A fibrous arch completes the half ring formed by the interval between the 
 first two metacarpal bones for the passage of this artery. The external head of the 
 muscle arises from the upper half of the inner border of the first metacarpal bone ; the 
 internal from the entire length of the external surface of the second metacarpal bone, 
 and from the hgaments which unite it to the trapezium. From these points the fleshy 
 fibres proceed, forming two thick bundles, which are perfectly distinct above, and con- 
 verge to a tendon that is attached to the outer side of the first phalanx of the index finger. 
 
264 
 
 BIYOLOGY. 
 
 Relations. — It is covered behind by the skin ; it corresponds in front to the adductoi 
 and flexor brevis pollicis, excepting below, where it is sub-cutaneous. Its lower edge, 
 directed obliquely downward and inward, is immediately sub-cutaneous, and crosses the 
 corresponding edge of the adductor pollicis at a very acute angle. 
 
 The Palmar Interossei. 
 
 These, like the preceding, are short, prismatic, triangular, and penniform muscles. 
 They are three in number (p p p, fig. 123) according to most authors, but four if we in- 
 clude the adductor pollicis. They all occupy the palm of the hand, as their name indi- 
 cates, and extend from the entire length of one of the metacarpal bones bounding the 
 interosseous space in which they are situated to the first phalanx of one of the corre- 
 sponding fingers, and to its extensor tendon. 
 
 They arise from about the anterior two thirds of the lateral surface of only one meta- 
 carpal bone ; they are, therefore, covered behind by the dorsal interossei, wliich, being 
 attached to the entire lateral surface of the other metacarpal bone, project equally into 
 the palm. Lastly, their insertions into the phalanges and their extensor tendons corre- 
 spond precisely with those of the dorsal interossei. 
 
 Relations. — They are covered by the flexor tendons and by the muscles of the palmar 
 region : each is in relation behind with a dorsal interosseous muscle ; on one side with 
 the dorsal muscle of the corresponding finger, and on the other with the metacarpal bone 
 from which it arises. 
 
 Action. — They are evidently adductors, as regards the axis of the hand, and, like the 
 dorsal interossei, they bind down the extensor tendons ; they can only act effectuall) 
 when the fingers have been previously extended. 
 
 MUSCLES OF THE LOWER EXTREMITIES. 
 
 The muscles of the lower extremities may be arranged in four groups, viz., those ol 
 the pelvis, of the thigh, of the leg, and of the foot. 
 
 MUSCLES OF THE PELVIS. 
 
 The Glutcei, Maximus, Medius, et Minimus. — Pyriformis. — Obturator Internus. — Gcmelb, 
 Superior et Inferior. — Quadratus Femoris. — Obturator Externus. — Action of these Muscles 
 
 fig, 1S4, The muscles of the pelvis are divided into those occupy 
 
 ing the posterior and those occupying the anterior region. 
 The former are very numerous, consisting of the three glutaei, 
 maximus, medius, and minimus, the pyriformis, the obturatoi 
 internus, the gemelli, the quadratus femoris, and the obtura- 
 tor externus. 
 
 The iliacus, which may with propriety be considered as be- 
 longing to the pelvis, and as forming its anterior vregion, hsis 
 been already described, together with the psoas, under the 
 name of the psoas-iliac muscle. 
 
 The GlutcBUs Maximus. 
 
 Dissection. — Having placed the subject on its face, raise the 
 pelvis by a block, flex the leg forcibly, and rotate it inward ; 
 then make an oblique incision along the middle of the but- 
 tock, from the sacrum towards the great trochanter, dividing 
 both the skin and fascia covering the muscle : dissect up the 
 tw(( "aps, one from below upward, the other from above down- 
 wani, following the direction of the muscular fibres. 
 
 The idutaus maximus {a, fig. 124) is the most superficial of 
 the muscles on the posterior aspect of the pelvis ; it is broad, 
 thick, and pretty regidarly quadrilateral ; it is the largest mus- 
 cle of the human body, in this respect coinciding with the 
 great size of the pelvis and femur in man ; it causes the prom- 
 inence of the buttocks. Its great size is one of the most dis- 
 tinctive characters of the muscular system of man, and has 
 reference to his biped position. 
 
 Attachments (see a, fig. 125). — It arises from the posterior 
 semicircular line of the ilium, and the portion of the bone be- 
 hind that line ; from the vertical sacro-iliac ligament, and the 
 outer margin of the common aponeurosis of the posterior spi- 
 nal muscles ; from the crest of the sacrum, sometimes only 
 from the tubercles which form a continuation of the trans- 
 verse processes of the vertebrae on the outside of the posteiior 
 
THE GLUTiEUS MEDIUS. 265 
 
 sacral foramina ; from the edges of the coccyx, and the notch terminating the crest of the 
 sacrum below, this origin being often effected by means of a tendinous arch, under which 
 the last posterior sacral nerves pass ; from the posterior surface of the great sacro-sci- 
 atic ligament ; and, lastly, from the posterior surface of the aponeurosis of the glutseus 
 medius. It is inserted {a, fig. 125) into the rough line leading from the great trochanter 
 to the linea aspera of the femur. 
 
 The fleshy fibres arise either directly or by short tendinous fibres, and proceeding par- 
 allel to each other outward, and a little downward, unite into large distinct fasciculi, ca- 
 pable of being separated through their entire length, and constituting an extremely thick, 
 quadrilateral, and very regular muscle, which, having reached the outside of the thigh, 
 terminates by tendinous fibres. These are received between two layers of the fascia 
 lata, which is here very thick ; in passing downward they converge, escape from the 
 fascia lata, curve round the base of the great trochanter, or, rather, the tendon of the vas- 
 tus externus, from which they are separated by a synovial bursa, and are successively 
 inserted by so many large fasciculi into the series of tubercles and depressions, extend- 
 ing from the great trochanter to the linea aspera, and from the external bifurcation of 
 that line. The lower fleshy fibres are attached directly to the linea aspera, and a cer- 
 tain number are inserted merely into the fascia lata. In order to obtain a good view of 
 the femoral insertions of this muscle, its tendon must be separated from the fascia lata. 
 
 Relations. — It is covered by a large quantity of fat, being separated from it by an ex- 
 pansion from the aponeurosis of the glutaeus medius, from which are given off the cellu- 
 lar prolongations that divide the muscle into thick, parallel, and easily separable fasciculi. 
 
 It covers the glutaeus medius, the pyriformis, the gemelli, the obturator internus, the 
 quadratus femoris, the great sciatic notch, and the tuberosity of the ischium, together 
 with the muscles attached to it, viz., the semi-tendinosus, the semi-membranosus, and 
 the long head of the biceps. It covers also the great trochanter, the adductor magnus, 
 and the triceps femoris, the glutaeal, ischiatic, and internal pudic vessels and nerves, and 
 the great sciatic nerves. Its upper border is very thin, and rests upon the glutaeus me- 
 dius ; its lower border forms a very marked prominence beneath the skin, that affords 
 the surgeon very precise indications, both in the diagnosis of many diseases of the hip- 
 joint ; in operations performed for the purpose of reaching the tuberosity of the ischium, 
 when it is either carious or necrosed ; in those for the relief of sciatic hernia ; or, lastly, 
 in searching for the sciatic nerve, whenever it becomes necessary to operate upon it. 
 Several bursae mucosae, which have been well described by Monro, separate the glutaeus 
 maximus from the eminences which are covered by it. One of these separates it from 
 the great trochanter, and is almost always multi-locular : I have seen it filled with a san- 
 guineous synovia. A second exists over the tuberosity of the ischium, but is often want- 
 ing ; and a third between the tendon of this muscle and the vastus externus.* 
 
 Action. — The glutaeus maximus is an extensor, an abductor, and a rotator of the thigh 
 outward. When the femur is fixed, as in standing, it acts upon the pelvis, which it draws 
 backward and to its own side, and rotates so that the anterior surface of the trunk is 
 turned to the opposite side. Besides this, it is easy to see that the lower fibres can act 
 as adductors. By its connexions with the fascia lata, it is one of the principal tensors of 
 this structure ; by its attachment to the coccyx, it tends to prevent that bone from being 
 thrown backward, forward, or to one side. 
 
 The Glut (BUS Medius. 
 
 Dissection. — Make a vertical incision through the middle of the glutaeus maximus, or 
 detach that muscle from the pelvis ; remove the adipose tissue from the sub-cutaneous 
 portion of the muscle, and also the fascia lata ; dissect the tensor vaginae femoris, which 
 covers the anterior fibres of this muscle. 
 
 The glutaus medius (b,figs. 124 to 127) is intermediate to the other two glutaei, both as 
 regards size and position ; it is a broad, thick, radiated muscle, situated more deeply 
 than the preceding, beyond which it projects upward and forward (^fig. 124). The glu- 
 taeus maximus is attached to a small portion only of the iliac fossa : the glutaei medius 
 and minimus share almost the whole of it between them. 
 
 Attachments. — It arises from the whole extent of the curved triangular surface included 
 between the superior semicircular line behind, the anterior three fourths of the crest of 
 the ilium above, and the inferior semicircular line below ; from the anterior superior 
 spine of the ilium and the notch immediately below it ; from the deep surface of a dense 
 aponeurosis, which is inserted into the outer lip of the crest of the ilium, covers all the 
 upper portion of the muscle, and becomes continuous with the fascia lata : opposite the 
 junction of the anterior with the middle third of the crest of the ilium, at which point a 
 large tubercle exists upon the bone, this aponeurosis is so dense as to resemble a tendon. 
 The muscle also arises from a deep aponeurosis, extending from the anterior part of the 
 inferior semicircular line, and giving attachment, on its external surface, to a great num 
 her of fleshy fibres ; and, lastly, from the fascia lata internally to the tensor vaginae femo 
 ris. It is inserted into the external surface of the great trochanter {figs. 125, 127) 
 
 * See note, p. 296. 
 L L 
 
k 
 
 266 MYOLOGY. 
 
 From these numerous origins the fleshy fibres proceed in different directions ; the pos- 
 terior forward, the middle vertically, and the anterior backward, becoming more and more 
 horizontal in front. They all terminate upon the two surfaces and edges of a radiated 
 aponeurosis, the fibres of which are gradually concentrated, and folded upon themselves, 
 so as to form a flat tendon, inserted, not into the upper border, as it is generally said, but 
 into the external surface of the great trochanter, along an oblique line running downward 
 and forward, so that the anterior fibres of the muscle are inserted into the anterior ex- 
 tremity of the lower border of the great trochanter, and the posterior fibres into the back 
 part of the upper border ; at this latter point a well-marked projection sometimes exists, 
 the size of which generjdly indicates the power of the glutaeus medius. A synovial bursa 
 intervenes between the tendon and that part of the great trochanter over which it passes.* 
 
 Relations. — It is covered by the glutaeus maximus, the tensor vaginas femoris, and the 
 skin : it covers the glutaeus minimus, with which its outer border is blended, and the 
 glutaeal vessels and nerves. Its lower border is parallel with the pyriformis {fig. 125). 
 
 Action. — The glutaeus medius is both an extensor and an abductor of the thigh. More- 
 over, the anterior fibres rotate the femur inward, and the posterior outward ; but the for • 
 mer have the greater power, for they are more numerous, the muscle being twice or 
 thrice as thick in front as behind ; it is, therefore, an extensor, an abductor, and a rotator 
 inward of the thigh. Winslow denies that it is an extensor, and considers it only as an 
 abductor ; this is only true in the position of standing upon both feet. In the sitting pos- 
 ture, again, this muscle in some degree loses its power as an extensor and abductor, 
 and acts merely as a rotator. When the femur is fixed, as in standing, the glutaeus 
 medius extends the pelvis, draws it to its own side, and rotates it> so that the front of 
 the trunk is turned towards the same side. It co-operates with the glutaeus maxunus in 
 the first two motions, but antagonizes it in the last. Finally, its anterior fibres appear 
 to me calculated to flex the thigh upon the pelvis, especiaUy when the flexion has been 
 already contmienced by other muscles. 
 
 The Glutce.us Minimus. 
 
 The glutaus minimus (c,fig. 127) is exposed by simply cutting across the preceding 
 muscle, beneath which it lies ; it is thinner, and more regularly radiated. It arises from 
 the anterior part of the crest of the ilium, below the glutaeus medius, from the outside of 
 the sciatic notch, and from all that part of the external iliac fossa situated below the in- 
 ferior semicircular line : from these points the fibres converge, the middle passing ver- 
 tically, the posterior forward, and the anterior backward, to the deep surface of a radia- 
 ted aponeurosis, the fibres of which are collected together into bands, that are inserted 
 separately into the anterior border and anterior half of the upper border of the great tro- 
 chanter. Most commonly the posterior band is intimately attached to the tendon of the 
 pyriformis. 
 
 Relations. — It is covered by the glutaeus medius, with which its anterior fibres are 
 blended ; it covers the external iliac fossa, the reflected tendon of the rectus femoris, 
 and the upper part of the hip-joint, from which it is separated by some fatty cellular tissue. 
 
 Action. — It is much more directly an abductor than the preceding muscles. Its ante- 
 rior half rotates the thigh inward, and its posterior half outward. If the femur be fixed, 
 it extends the pelvis, inclines it to its own side, and turns the anterior aspect of the 
 trunk to the same side ; by its anterior fibres it assists slightly in producing flexion. 
 
 General Remarks upon the Action of the Glutcei. — The three muscles we have just ex- 
 amined generally have their fixed points upon the pelvis ; and, in this point of view, are 
 of the greatest importance in the standing posture. By their means the pelvis, firmly 
 held down from behind, is enabled to resist the effects of the weight of the trunk, which 
 tends to throw it forward : hence the enormous development of these muscles in man, 
 evidently proving his destination for the erect position. These same muscles are the 
 principal agents in the position of standing upon one foot, inclining the pelvis to their 
 own side, and balancing the entire weight of the opposite side of the trunk. They also 
 rotate the trunk when the individual is standing upon one foot. They are all extensors 
 and abductors ; the glutaeus maximus is a rotator outward ; the other two are rotators 
 inward. Hence we may understand how the thigh can be so powerfully rotated inward, 
 although there are no direct muscles for that purpose ; while a great number are spe- 
 cially intended to produce rotation outward, which movement, indeed, is performed 
 much more energetically than rotation inward. 
 
 The Pyriformis. 
 
 Dissection. — Detach the glutaeus maximus, and separate the pyriformis from the lowei 
 border of the glutaeus medius, to which it is parallel. In order to see the sacral attach- 
 ments of the muscle, make an antero-posterior section of the pelvis. 
 
 The pyriformis or pyramidalis {d, fig. 125) is sometimes double : it is a flat muscle, of 
 a p5Tifonn, or, rather, pyramidal shape, lying almost horizontally along the lower margin 
 of the glutaeus medius, with which it seems to be continuous, and is sometimes intimately 
 
 * See note, p. 296. 
 
THE OBTURATOR INTERNUS. 267 
 
 united : it is partly situated in the cavity of the pelvis, and assists in filling up the sciat- 
 ic notch. 
 
 Attachments. — It arises from the anterior surface of the sacrum (p,^. Ill), in the in- 
 tervals between the grooves forming the continuations of the anterior sacral foramina, 
 and also opposite those grooves, by three or four digitations, which are sometimes trav- 
 ersed by the great sciatic nerve : these origins are sometimes concentrated into a small 
 space around the second and third anterior sacral foramina. It also arises from the an- 
 terior surface of the great sacro-sciatic ligament, and from the upper part of the sciatic 
 notch. It is inserted into the back part of the upper edge of the great trochanter. The 
 fleshy fibres pass irom their origins almost horizontally outward and a little backward, 
 and form a muscle which fills up the upper part of the great sciatic notch, and, becoming 
 much narrower immediately after emerging from the pelvis, from the convergence of its 
 fibres, terminates on the posterior surface and edges of an aponeurosis, which is after- 
 ward converted into a round tendon, and is fixed to the upper border of the great tro- 
 chanter, behind the glutaeus minimus, and above the gemelU and obturator internus, with 
 which it is almost always intimately connected. 
 
 Relations. — Its anterior surface is in relation with the rectum, the sciatic plexus, and 
 the hypogastric vessels within the pelvis, and with the hip-joint outside that cavity ; its 
 posterior surface, with the sacrum and the glutaeus maximus ; its upper margin, with the 
 glutaeal vessels and nerves, which separate it from the glutaeus medius ; its lower mar- 
 gin, with the ischiatic vessels, and with the great and small sciatic nerves. Sciatic her- 
 niae take place between the upper margin of this muscle and the sciatic notch. Some- 
 times the muscle reaches the summit of the notch ; occasionally, a considerable interval 
 exists between them ; in such cases, there is a predisposition to this species of hemiae. 
 
 The Obturator Internus. 
 
 The oUurator internus {e,fig. 125) is a triangular reflected muscle, extending from the 
 inner surface of the margin of the obturator foramen to the digital cavity of the great 
 trochanter. Its course and direction are alike remarkable. 
 
 Attachments. — It arises from the posterior surface of the obturator ligament, from the 
 pelvic fascia lining the inner surface of this muscle, and from the tendinous arch which 
 converts the sub-jmbic groove into a canal ; also, from the entire circumference of the ob- 
 turator foramen, viz., from the internal surface of the descending ramus of the pubes and 
 the ascending ramus of the ischium, and from the whole extent of the quadrilateral sur- 
 face situated between the obturator foramen and the sciatic notch ; and, lastly, by a few 
 fibres from the brim of the pelvis. It is inserted into the digital cavity of the great tro- 
 chanter. The fleshy fibres arise directly from this extensive surface, and, converging 
 downward and outward, pass out of the pelvis through a triangular opening formed by the 
 spine of the ischium and lesser sacro-sciatic ligament above, by the great sacro-sciatic 
 ligament on the inside, and by the body of the ischium on the outside. At its exit from 
 the pelvis the muscle becomes much narrower, is reflected at a right angle over the body 
 of the ischium as over a pulley, is next received into a groove formed for it by the gemelli, 
 and proceeds horizontally outward, to be inserted into the digital cavity of the great tro- 
 chanter below the pyriformis. In order to obtain a good view of the structure of this 
 muscle, it must be detached from its insertion and turned inward. We shall then per- 
 ceive that the tendon divides into four or five diverging portions upon the deep surface 
 of the muscle, which are lost in its interior. A well-marked synovial membrane* inter- 
 venes between the tendon and the trochlear surface on the body of the ischium, which 
 is covered with cartilage that is streaked, as it were, in the direction of the movements. 
 Cowper and Douglas alluded to the presence of this bursa when they named the muscle 
 marsupialis vel bursalis. 
 
 Relations. — In the pelvis the obturator internus is in relation with the obturator liga- 
 ment and the circumference of the obturator foramen, by its anterior surface ; and with 
 the pelvic fascia and levator ani muscle, which separates it from the bladder, by its pos- 
 terior surface. During its passage through the orifice I have described, it is in relation 
 with the internal pudic vessels and nerves ; externally to the pelvis, it is covered by the 
 great sciatic nerve and the glutaeus maximus, and it covers the hip-joint. 
 
 From the great extent of the pelvic origins of this muscle, almost the whole of the an- 
 terior and lateral parietes of the pelvis are covered internally by a layer of muscular tis- 
 sue ; the posterior wall is also in a great measure covered by the pyriformis. 
 
 The origin' of the muscular fibres from the tendinous arch of the obturator ligament 
 are so arranged, that the contraction of the muscle can have no effect in diminishing the 
 size of the sub-pubic foramen intended for the passage of vessels and nerves. There 
 are sometimes two small tendinous arches ; one for the nerve, the other for the artery 
 and vein. 
 
 The Gemelli, Superior et Inferior. 
 The gemelli (gemini, Albinus ; les petits jumeaux, Winslaw, f and g, Jig. 135), two small 
 
 1 See note, p. 295. 
 
268 MYOLOGY. 
 
 fleshy fasciculi, accessories to the obturator intemus, are generally distinguished by anat- 
 omists into the superior (/) and the inferior (g) ; they are separated from each other by 
 the tendon of the obturator intemus, for the reception of which they form a groove. 
 Above and below this groove they take their origin ; the superior from the spine of the 
 ischium, and the inferior, which is the larger, from the tuberosity of that bone, immedi- 
 ately above the attachment of the great sacro-sciatic ligament, and even slightly from 
 the ligament itself They both pass horizontally outward, are sometimes united either 
 behind or in front of the tendon of the obturator intemus, which they then completely 
 embrace, and with which they are entirely or partially blended, being inserted with it into 
 the digital cavity of the great trochanter. 
 
 Their relations are the same as those of the reflected portion of the obturator intemus. 
 The gemellus superior is often wanting, and the inferior is frequently double. I have 
 several times seen the superior terminate in the tendon of the pyriformis, and the in- 
 ferior in the tendon of the obturator intemus. 
 
 Actimi. — They rotate the thigh outward. Their relations with the synovial capsule of 
 the obturator intemus led to their being designated marsupiales by Cowper, and by Portal, 
 le muscle capsulaire de la capsule du tendon de I'obturateur interne. 
 
 The Quadratus Femoris. 
 
 This muscle (i, fig. 125), shaped like a parallelogram, is situated immediately below 
 the gemellus inferior. It arises from the external border of the tuberosity of the ischium, 
 in front of the semi-membranosus, from which it is separated by adipose tissue. From 
 this point the fibres proceed horizontally outward, parallel to each other, and are inserted 
 into " an oblong ridge* projecting partly from the back of the root of the great trochan- 
 ter, and partly from the femur immediately below it ;" but above the attachment of the 
 adductor magnus, with which, at first, it appears to be continuous, but from which it is 
 always separated by the internal circumflex vessels. 
 
 This muscle is sometimes wanting ; but very frequently its pelvic attachments are pro- 
 longed as far as the ascending ramus of the ischium ; in which cases it is twisted inferi- 
 orly upon itself, so as to oppose a surface, not a border, to the adductor magnus. Its re- 
 lations behind are the same as those of the preceding muscles ; in front, it covers the 
 obturator externus and the lesser trochanter, from which it is often separated by a sy- 
 novial capsule. 
 
 The Obturator Externus. 
 
 Dissection. — The lower or horizontal portion of the obturator externus is exposed, by 
 dividing the quadratus femoris into two equal parts by a vertical incision. In order to 
 see the upper or pelvic portion, it is necessary to detach the gracilis, pectineus, psoas, ili- 
 acus, and adductor brevis. 
 
 This is a triangular, flat muscle (e, fig. 127), of the same shape, but thinner and smallei 
 than the obturator intemus, and, like it, reflected, though at an obtuse angle. It arises 
 from the circumference of the obturator foramen, from the obturator ligament, and from 
 the tendinous arch which completes the sub-pubic canal for the vessels and nerve. It 
 is inserted into the deepest and lowest part of the digital cavity of the great trochanter. 
 The fleshy fibres arise directly, the lower ones proceed horizontally outward, and the 
 upper obliquely downward, backward, and outward ; thus converging, they form a fleshy 
 belly, which turns round the neck of the femur, and terminates in a tendon that passes 
 horizontally outward, to be inserted into the digital cavity, below the gemelli and the ob- 
 turator intemus. 
 
 Relations. — Its outer and anterior surface is in relation with the pectineus, the adduc- 
 tors, the psoas and iliacus muscles, and more externally with the neck of the femur and 
 the lower part of the capsular ligament of the hip-joint. Its inner and posterior surface 
 is in contact with the obturator foramen and the quadratus muscle. 
 
 Action of the preceding Muscles. 
 
 The last six muscles are evidently rotators of the thigh outward. The pyriformis, the 
 gemelli, and the obturator internus, which are almost always united at their insertions, 
 would deserve the name of quadri-gemini, given by the older anatomists to the gemeUi, 
 the pyriformis, and the quadratus. When they take their fixed point upon the femur, as, 
 for example, in standing upon one foot, they become rotators of the pelvis, and turn the 
 anterior surface of the trunk to the opposite side. They are only rotators when tlie limb 
 is extended ; in the sitting posture, they become abductors. Winslow, who first demon- 
 strated their use in abduction in the semiflexed position, attached great importance to 
 the connexion of so many of these muscles with the capsular ligament, which he believed 
 prevented pinching of the capsule during the different movements of the joint. 
 
 The insertion of these muscles is exceedingly favourable. Moreover, we shall find, 
 that besides the glutaeus maximus and the posterior fibres of the glutaeus medius and 
 
 * [M. Cruveilhier states the insertion of the quadratus femoris to be into the inter-trochanteric line. Tba 
 description in the text, copied from Albinus, gives a more accurate idea of the insertion of this muscle.] 
 
THE BICEPS CRURIS. 
 
 minimus, they have many other muscles as accessories in rotation. The effects pro- 
 duced by the contraction of the two obturators can be easily understood, if we bear in 
 mind that the action of a reflected muscle is to be calculated from the point of reflection, 
 leaving the rest of the muscle out of consideration. Thus, with regard to the obturator 
 internus, the sciatic notch acts as a pulley, and may be regarded as the fixed point. 
 
 MUSCLES OF THE THIGH. 
 
 The Biceps Cruris. — Semi-tendinosus. — Semi-memhranosus. — Tensor Vagina. Femoris. — 
 Sartorius. — Triceps Extensor Cruris. — Gracilis. — Adductor Muscles of the Thigh. 
 
 The muscles of the thigh are divided into those of the posterior region, viz., the biceps, 
 the semi-tendinosus, and the semi-membranosus ; those of the external region, viz., the 
 tensor vaginae femoris and the vastus externus ; those of the anterior region, viz., the 
 sartorius, the rectus, and the triceps extensor cruris of authors ; and, lastly, those of the 
 internal region, viz., the gracilis, the pectineus, and the three adductors. 
 
 Posterior Region. 
 
 The Biceps Cruris. 
 
 Dissection. — This is the same for the biceps, the semi-tendinosus, and the semi-mem- 
 branosus. Place the subject upon its face, with a block under the pelvis, and allow the 
 leg to hang over one side of the table. Make an incision from the middle of the space 
 between the tuberosity of the ischium and the great trochanter to the interval between 
 the two condyles of the femur. Both the skin and the fascia of the thigh must be di- 
 vided in this incision. Cautiously remove the cellular and adipose tissue surrounding 
 the subjacent muscles, the relations of which with the popliteal vessels and nerves must 
 be carefully studied. In preparing the superior attachments of these muscles, the glu 
 iaeus maxiraus must be divided in the middle, perpendicularly to its fibres. 
 
 The biceps femoris (biceps cruris, Albinus, I, figs. 124, 125), so named because it con- 
 sists of two fleshy bodies or heads above, is a long, large muscle, situated on the poste- 
 rior and external aspect of the thigh. 
 
 Attachments. — It arises from the tuberosity of the ischium and the linea aspera of the 
 femur, and is inserted into the head of the fibula, and slightly jp^. 125. 
 
 into the external tuberosity of the tibia. Its origin from the 
 
 ischium {I, fig. 125) is common to it and the semi-tendinosus ; -;; ■; ^^f ; 
 
 it takes place, not from the tuberosity properly so called, but 
 from the highest and most external part of the tuberosity, 
 above and behind the adductor magnus, and immediately be- 
 low the gemellus inferior. It arises by a tendon which is sel- 
 dom completely free from muscular fibres. This tendon, at 
 first very thick, and separated from the tuberosity of the 
 ischium by a synovial bursa, expands into an aponeurosis, 
 which gives origin to the fleshy fibres of the biceps by its ex- 
 ternal edge and posterior surface, and to those of the semi- 
 tendinosus by its internal surface. Up to this point the biceps 
 and semi-tendinosus are blended together so as to form a single 
 fleshy belly, which, after extending from two to four inches, is 
 divided into two portions : one posterior and external, consti- 
 tuting the long head, or ischiatic portion of the biceps ; the other 
 anterior, forming the origin of the semi-tendinosus, which we 
 shall next describe. Arising thus in succession, the fleshy 
 fibres of the long head of the biceps form a fusiform belly 
 passing obliquely downward and a little outward, and termina- 
 ting on the anterior surface of an aponeurosis, which extends 
 for a considerable distance on the posterior surface of the 
 muscle, and which gradually becomes contracted, so as to 
 form the terminal tendon. Just where these fleshy fibres are 
 about to terminate {l,Jig. 125), the aponeurosis receives upon 
 its anterior surface and external edge the fleshy fibres of the 
 short head, or femoral porticm of the biceps. This portion of 
 the muscle {I', fig. 125) arises from the greater part of the in- 
 terval between the two margins of the linea aspera, and the 
 posterior surface of the external inter-muscular septum of the 
 thigh ; it passes downward, inward, and backward, to be at- 
 '.ached to the common tendon, almost as far as its insertion. 
 This insertion is not confined to the head of the fibula, but extends also to the external 
 tuberosity of the tibia by means of a strong division of the tendon, which, at the same 
 time, gives ofF^n expansion to the fascia of the leg. The insertion into the fibula is ef- 
 
2^0 MYOLOGY. 
 
 fected on the outer side, in front of and behind the extemzd lateral ligament of the knee- 
 joint, which ligament it embraces in a bifurcation. 
 
 Relations. — The biceps is covered by the glutaeus maximus and the femoral fascia. It 
 covers the semi-tendinosus, semi-membranosus, and vastus externus. It is in relation, 
 also, with the great sciatic nerve, which is placed at first externally, then in front, and, 
 lastly, on the inside of the muscle ; finally, its short head is in relation with the popliteal 
 vessels. 
 
 The biceps forms the external border of the popliteal space ; near its termination it 
 is in relation with the outer head of the gastrocnemius and with the plantaris longus 
 muscle. 
 
 Action. — The biceps flexes the leg upon the thigh. When this movement is com- 
 pleted, its long portion extends the thigh upon the pelvis. From its obliquity downward 
 and outward, it rotates the leg outward during semi-flexion ; but this rotation is impos- 
 sible when the leg is extended, in consequence of the tension of the crucial ligaments. 
 The fixed point of this muscle is as often below as above, and it then performs an im- 
 portant part in the mechanism of standing ; for it tends to prevent the individual from 
 ialhng forward, because it holds back the pelvis. When the pelvis is thrown quite back- 
 ward, this muscle can then flex the thigh upon the leg. 
 
 The Semi-tendinosus. 
 
 The semi-tendinosus {m,figs. 124, 125), so named on account of the great lengta of its 
 tendon, is situated on the posterior and internal aspect of the thigh. 
 
 AttcLchments. — It arises from the tuberosity of the ischium, and is inserted into the an- 
 terior tuberosity of the tibia. Its origin (m, fig. 125) consists of a tendon common to it 
 and the long head of the biceps, which is prolonged in the form of an aponeurosis, upon 
 the external (or popliteal) border of the muscle. Some of the fleshy fibres are attached 
 directly to the tuberosity of the ischium. Having arisen in this manner, it enlarges and 
 constitutes a fusiform bundle, which passes at first vertically downward, and then ob- 
 liquely inward. About four or five fingers' breadth above the knee-joint it terminates in 
 a long, thin tendon, which turns round the internal tuberosity of the tibia, describing a 
 curve having its concavity directed forward, and is then reflected horizontally forward, 
 to be inserted into the anterior teberosity of that bone, behind the tendon of the sarto- 
 rius, and parallel with the lower edge of that of the gracilis, to which it is united. The 
 union of these three tendons constitutes the patte d'oie (goose's foot). 
 
 The length of its tendon of insertion is the most characteristic feature of the muscle ; 
 and hence its name, semi-nervosus (Spigelius), and le demi-nerveux ( Winslow), for which 
 the term semi-tendinous has now been substituted. The structure oi this muscle is re- 
 markable. The fleshy fibres are interrupted across the middle by a tendinous intersec- 
 tion, analogous to that of the great complexus, which gives origin to new fleshy fibres. 
 
 Relations. — It is covered by the glutaeus maximus and the femoral fascia, and it cov- 
 ers the semi-membranosus and part of the upper portion of the adductor magnus. Its 
 tendon is first placed behind the semi-membranosus, and then, before it turns round the 
 internal tuberosity of the tibia, between the tendon of that muscle and the inner head of 
 the gastrocnemius. 
 
 Action. — ^The same as that of the biceps. It is a very powerful flexor, on account of 
 the reflection of its tendon. Its oblique direction enables it to rotate the tibia inward du 
 ring semi-flexion of the leg. It is, therefore, a congener of the popliteus. 
 
 The Semi-membranosus. 
 
 The semi-membranosus {n,figs. 124, 125) is situated upon the posterior aspect of the 
 thigh, thin and aponeurotic above, thick and fleshy below. 
 
 Attachments. — It arises from the upper and outermost part of the tuberosity of the is- 
 chium, in front of the biceps and semi-tendinosus ; and is inserted into the internal tuber 
 osity of the tibia, and also, by an expansion of its tendon, into the femur. It arises by 
 means of a very thick tendon, which becomes wider immediately after its origin. From 
 its inner border is given off" an aponeurotic lamina, that splits into two layers, from the in- 
 terval between which the superior fleshy fibres arise. Lower down, the muscular fibres 
 proceed directly from the tendon itself, which runs along the outer (or popliteal) border 
 of the muscle, as far as the lower fourth of the thigh, but is afterward buried in its sub- 
 stance. The union of all these fibres constitutes a very thick, four-sided, fleshy belly, 
 which is received into a tendinous semi-cone, open on its outer side, and soon becoming 
 converted into a thick tendon, which, after a passage of a few lines, separates into three 
 divisions, terminating in the following manner : the posterior division passes inward and 
 upward, forms the chief part of the posterior ligament of the knee-joint, and is inserted 
 into the femur ; the middle division is attached to the back of the internal tuberosity of 
 the tibia, below the articular surface ; the third is horizontal, and turns round the inter- 
 nal tuberosity of that bone in the horizontal furrow existing there, and is inserted on the 
 inner side of the tuberosity. A synovial bursa intervenes between it and the bone. 
 
 Relations. — The semi-membranosus is covered by the glutaeus maximus, the semi-ten- 
 
THE TENSOR VAGINA FEMORIS. THE SARTORIUS. 271 
 
 dinosus, the biceps, and the femoral fascia : it covers the quadratus femoris, the adduc- 
 tor niagnus, and the inner head of the gastrocnemius. A synovial membrane separates 
 it from the knee-joint. It also covers the popliteal artery and vein, which soon come 
 into relation with its outer or popliteal border. The sciatic nerve lies parallel with its 
 outer border through the whole of its extent ; the gracilis is in contact with its inner 
 border. I shall remark here, that the biceps on the outside, and the semi-membranosus 
 and semi-tendinosus on the inside, constitute the lateral boundaries of a cellular interval 
 which extends along the whole of the back of the thigh, and is continuous with the pop- 
 liteal space. This large cellular interval communicates above with the cellular tissue 
 of the pelvis at the sciatic notch, and below with the fossa of the ham. It is in this di- 
 rection that purulent matter so readily escapes from the pelvis. The greater part of 
 this interval is destined for the great sciatic nerve, which, however, is soon accompani- 
 ed by the popliteal vessels. 
 
 Action. — Precisely similar in nature to that of the preceding muscle, but much more 
 powerful. The momentum of all these flexor muscles occurs, on the one hand, during 
 semi-flexion of the leg upon the thigh ; and, on the other (i. e., when their lower attach- 
 ments are fixed), during semi-flexion of the thigh upon the pelvis. 
 
 External Region. 
 
 The Tensor Vagince Femoris. 
 
 Dissection. — In order to expose this muscle, it is sufficient to make a vertical incision 
 through the thick, tendinous layer given off from the anterior portion of the crest of the 
 ilimn, and to dissect back the two flaps of that aponeurosis. 
 
 The tensor vagina femoris (le muscle du fascia lata, o,fig. 126) is the largest of all the 
 extensor muscles of aponeuroses : it is a short, flat, quadrilateral muscle, contained within 
 the substance of the fascia lata, and occupying the upper third of the external region of 
 the thigh. It arises from the anterior part of the outer margin of the crest of the ilium, 
 and from the outer border of the anterior superior spinous process of the ilium, between 
 the sartorius and the glutasus medius, by means of a tendon, which also furnishes some 
 points of attachment to the anterior fibres of the last-named muscle. From these points 
 the fleshy fibres proceed downward and a little backward, and, at about the upper fourth 
 or third of the thigh, terminate in a series of small tendinous bundles, the anterior of 
 which become continuous with the fascia lata, while the posterior cross obliquely over 
 the vertical fibres of the fascia, with which they are very soon blended. 
 
 Relations. — It lies between two layers of the fascia lata, the external layer being much 
 thicker than the internal. It is covered by the skin, and it covers the glutaeus medius, 
 the rectus, and the vastus extemus. Its anterior border is in contact with the outer 
 edge of the sartorius, but is soon separated from it by a triangular space, in which the 
 rectus femoris may be seen. ' 
 
 Action. — It is a tensor, not only of the entire femoral fascia, but particularly of the very 
 dense portion or band of the fascia lata, which, being continuous with it, may be regard- 
 ed as an aponeurotic tendon to this muscle (muscle aponeurotique de la bande large, 
 Winslow), and which is inserted into the outer tubercle of the anterior tuberosity of the 
 tibia, and into the adjacent part of its external tuberosity. When the tensor vaginae is 
 in action, this band compresses the vastus extemus, which has so great a tendency to 
 displacement ; by means of this band, also, the muscle acts upon and extends the leg. 
 Lastly, on account of its slight obliquity downward and backward, it may be regarded as 
 a rotator of the thigh inward ; it is but little concerned, however, in the production of 
 this movement, which, as I have already said, is chiefly effected by the anterior fibres 
 of the glutaei medius and minimus. 
 
 Anterior Region. 
 
 The Sartorius. 
 
 Dissection. — This is common to all the muscles of the anterior and inner regions ol 
 the thigh. Make a horizontal incision along the fem.oral arch, and another perpendicu- 
 larly from the middle of that to the anterior tuberosity of the tibia. Dissect the fascia 
 of the thigh with care. As all the muscles of the anterior and inner region are separa- 
 ted from each other by distinct sheaths, their dissection consists simply in opening these 
 sheaths successively, and removing the cellular tissue that fills up the inter-muscular spa- 
 ces. It is necessary to preserve the vessels, in order to obtain a good view of their rela- 
 tions : avoid opening the vena saphena, as it generally contains a large quantity of blood, 
 the escape of which will impede the dissection. If the vein should be opened, it must be 
 tied above and below the orifice, and then cut across. When the superficial muscles 
 have been studied, they must be divided in the middle, in Order to expose the muscles 
 of the deep layers. 
 
 The sartorius {p, fig. 126), so named on account of its uses, crosses diagonally over the 
 anterior, and then the inner part of the thigh, to the top of the leg. It is the longest mus- 
 cle in the body, both as regards its total length, and more especially in reference to the 
 
«72 
 
 MYOLOGY. 
 
 Fig- 126. length of its fibres ; whence the name of longus, given to it by 
 
 Riolanus. This is the case even although it be nneasured by a 
 line stretched directly between its two extremities. 
 
 Attachments. — It arises from the anterior superior spinous pro- 
 cess of the ilium, from the upper half of the notch below that pro- 
 cess, and from a tendinous septum between the muscle and the 
 fascia lata. It is inserted into the inner margin of the crest of the 
 tibia, situated beneath the ligamentum patellae. Its origin con- 
 sists of some tendinous fibres, which are more marked beb md and 
 on the outer side than in front and within. The fleshy fibres 
 commence almost immediately, and form a flat, riband-like mus- 
 cle (fascialis, Spigelius), which in reality is prismatic and trian- 
 gular, as well as the tendinous sheath in which it is enclosed. 
 The muscle increases in breadth as far as the lower third of the 
 thigh, and passes obliquely downward, inward, and a little back- 
 ward ; it becomes internal and vertical at the lower third (p, Jigs. 
 124, 125), and reaches the back part of the inner condyle of the 
 femur, to turn round the knee-joint, tendinous fibres having al- 
 ready conmienced on the anterior edge of the muscle. The fleshy 
 fibres terminate precisely where the muscle changes its direction 
 to pass forward. The flat tendon by which they are succeeded is 
 at first narrow, but becomes considerably expanded, to be inserted 
 into the crest of the tibia, in front of the tendons of the semi-ten- 
 dinosus and gracilis muscles, with which it is united, so as to 
 form what is called the patte d'oie (goose's foot). A synovial 
 membrane separates it from the tendons of these muscles. A 
 considerable tendinous expansion is given off from its lower edge, 
 and contributes to form the inner part of the fascia of the leg. 
 
 Relations. — ^The sartorius is the most superficial muscle in the 
 anterior aspect of the thigh ; it lies beneath the femoral fascia, 
 and covers the psoas and iliacus, the rectus, the vastus internus, 
 the adductor longus, the gracilis, the adductor magnus, and the 
 internal lateral ligament of the knee-joint. The borders of this 
 muscle deserve particular attention, because incisions for ligature 
 of the femoral artery must be made along them. Its most important relation, indeed, is 
 with the femoral artery and vein ; it is the satellite muscle of the femoral artery. Thus, 
 in the upper third of the thigh, it forms, with the adductor longus and femoral arch, an 
 isosceles triangle, having its base turned upward, and the femoral artery represents a 
 perpendicular drawn from the apex to the base of the triangle. In the middle third of 
 the thigh, the artery is in relation, first, with the inner border, then with the posterior 
 surface, and, lastly, with the outer border of the muscle. In the lower third, the sarto- 
 rius occupies a deep groove, formed by the gracilis and vastus internus ; from the latter 
 muscle it is separated below by an interval containing adipose tissue, of which circum- 
 stance advantage may be taken in the application of issues. It also covers the saphenus 
 nerve (a deep branch of the anterior crured), which emerges from beneath its anterior bor- 
 der, opposite the lowermost point of insertion of the adductor magnus. Near the knee- 
 joint, the saphena vein is in relation with the posterior border of the muscle. 
 
 The structure of the sartorius is very simple. The fleshy and tendinous fibres are all 
 parallel, and the former correspond exactly with the length of the muscle. 
 
 Action. — The sartorius flexes the leg upon the thigh, which it draws inward, so as to 
 cross one leg over the other. When this movement is produced, it flexes the thigh upon 
 the pelvis. If the fixed point of the muscle be at the leg, it then flexes the pelvis upon 
 the thigh, and rotates it, so that the anterior surface of the trunk is directed to the op- 
 posite side. 
 
 The Rectus Femoris and Triceps Extensor Cruris, or the Triceps Femoralis. 
 
 I have included under the name triceps femoralis the two muscles, or, rather, the two 
 parts of the same muscle, which are described separately in most anatomical works. 
 The reasons for this arrangement will be understood after the following description of 
 the muscle : 
 
 I shall consider the triceps femoralis as composed of three portions, viz., a middle or 
 long portion, the rectus femoris of authors ; an external and an internal portion, which 
 constitute together the triceps cruris of authors ; for these I shall retain the names of 
 vastus internus and externus, including in the former the middle portion or crureus, prop- 
 erly so called, of most anatomists. 
 
 The long portion of the triceps femoralis, or the rectus femoris (r, fig. 126), is situated in 
 the anterior region of the thigh, extending from the anterior inferior spinous process of 
 the ilium to the patella : it is vertical in its direction, thick and broad in the middle, and 
 narrowei at its extremities in..-;-r 
 
THE RECTUS FEMORIS AND TRICEPS EXTENSOR CRURIS. 273 
 
 It arises by a very strong tendon (r, fig. 127), which embraces the anterior inferior 
 spinous process of the ihum, and is proportioned to the power of the muscle. This ten- 
 don receives on its outer side another flat tendon, arising from a groove upon the rim 
 of the cotyloid cavity, and following its curvature ; this is the rejected tendon, which is 
 blended with and strengthens the straight tendon. It then expands into a broad aponeu- 
 rosis, the outer portion of which is very thin and prolonged over the anterior surface of 
 the muscle as far as the middle, while the inner portion is very thick, and penetrates 
 into its substance nearly as far as its insertion. The fleshy fibres arise from the poste- 
 rior surface and edges, and also from the anterior surface of the inner portion of this 
 aponeurosis ; they all pass downward and backward, the internal inward and the exter- 
 nal outward, and form a fleshy belly, which increases as it proceeds downward, and then 
 terminates on the anterior surface of a broad, thick, and shining aponeurosis, occupying 
 the lower two thirds of the posterior surface of the muscle, and soon becoming contract- 
 ed into a flat tendon, which receives upon its inner edge the superficial fibres of the 
 vastus intemus, again expands, and is finally blended with the common tendon of the 
 two vasti. 
 
 Triceps Femoris of Authors, or Vastus Internus and, Externus. — This is a voluminous 
 mass of muscular tissue, situated behind the preceding muscle, and extending from the 
 three surfaces of the shaft of the femur to the patella and tibia. It is commonly but er- 
 roneously considered to be divided above into three heads, which are described under 
 the names of vastus internus, vastus externus, and crureus. I have searched in vain for 
 the middle portion, but have never been able to find more than two separate parts : one 
 external, very large and superficial, viz., the vastus externus; the other internal, anteri- 
 or, and even external, viz., the vastus internus ; it is much smaller than the vastus ex- 
 ternus, and is partly covered by it and by the rectus. 
 
 The external portion, or vastus externus {s, figs. 124 to 127). This is the largest portion 
 of the triceps femoralis. It arises from a projecting border or horizontal crest, situated 
 at the base of the great trochanter, and from a vertical edge in front of that trochanter, 
 which forms a continuation of its anterior border, and sometimes presents a very prom- 
 inent tubercle : in the angle formed by these two attachments is situated tlie tendon of 
 the glutseus medius. It also arises along a line running from the great trochanter to the 
 linea aspera, and from the whole extent of the external lip of the linea aspera itself 
 All the preceding origins are effected by means of a broad aponeurosis which covers the 
 superior three fourths of the muscle, and from the deep surface of which almost all the 
 fleshy fibres proceed. Lastly, some of these arise from the tendon of the gluta?us max- 
 imus, and from the tendinous septum intervening between the vastus externus and the 
 short head of the biceps. From these origins the fleshy fibres proceed, some vertically 
 downward, the others somewhat obliquely downward and forward, the lowest being the 
 shortest and the most oblique ; they form a large bundle, which partially covers the an- 
 terior portion of the vastus intemus, but is separated from it by vessels, nerves, and cel- 
 lular tissue. After a course of variable length, some of the fleshy fibres are attached to 
 the deep, but the greater number to the superficial surface of another equally strong apo- 
 neurosis : this becomes thickened and contracted into a flat tendon, which is sometimes 
 divided into thick parallel bands, emerges from the fleshy fibres at the external margin 
 of the rectus, and is inserted into the outer half of the upper border of the patella, being 
 blended on the inner side with the rectus and the vastus intemus. The lower fleshy 
 fibres which arise from the inter-muscular septum are attached directly to the outer bor- 
 der of the patella.* 
 
 The internal or anterior portion, vastus internus {t and u,fig. 127), is much smaller than 
 the external, and surrounds the femur. Its inner portion lies immediately under the fas- 
 cia, and is the only part which is generally described as the vastus internus {t,figs. 126, 127). 
 Its anterior portion is covered by the rectus, or long portion, and is usually called the 
 crureus (cmralis, Alb., u,fig. 127). Its outer portion is covered by the vastus externus, 
 with which many of its fibres are blended ; but they may always be separated by cutting 
 along the outer margin' of the middle aponeurosis. Thus defined, the vastus internus 
 arises from a rough oblique line, extending from the front of the neck of the femur to the 
 linea aspera, and from the internal lip of the linea aspera itself, in front of the adductor 
 muscles : both of these origins are effected by means of an aponeurosis, which is weaker 
 and smaller than that of the vastus externus, and is blended with that of the adductors, 
 concurring w ith it in the formation of a canal for the femoral artery. It also arises from 
 almost the whole of the internal, anterior, and external surfaces, and from the two ante- 
 rior borders of the femur ; lastly, the lower fibres arise from the internal inter-muscular 
 septum. From these different origins the fleshy fibres pass in various directions ; the 
 external inward, the middle vertically, and the internal, which are the most numerous, 
 downward, forward, and outward ; they thus form a fleshy belly, thicker below and with- 
 in than above and without, and are successively attached to both surfaces, and espe- 
 cially to the posterior surface of a broad aponeurosis, which is covered by the tendon of 
 
 * Tke anterior border of this tendon is free, and perfectly distinct from the tendon of the rectus, which is 
 lined by it ; and also from the expanded tendon of the vastus internus. 
 
 Mm 
 
2T4 MYOLOGY. 
 
 the vastus externus, but can be easily separated from it. The uiner fibres are attached 
 to the anterior surface of the aponeurosis, and terminate very regularly opposite a verti- 
 cal line, running parallel to the inner margin of the rectus femoris. 
 
 The aponeurosis extends over the anterior surface of the middle portion of the mus- 
 cle, which lies behind the rectus : this fact has, doubtless, given rise to its division into 
 two parts, viz., a middle, or the crureus, and an internal, called the vastus internus. The 
 superficial layer of the interna! fleshy fibres is attached below to the inner margin of the 
 rectus, or long portion of the triceps femoralis : the lowest of these fibres, which arise 
 from the inner and inferior bifurcation of the linea aspera, and from the corresponding 
 inter-muscular septum, are almost horizontal, and accompany the tendon as far as its in- 
 sertion into the inner border of the patella. Lastly, the terminating aponeurosis is pro- 
 longed inward to the internal tuberosity of the tibia, below which it is inserted, being 
 covered by the tendons of the semi-tendinosus, semi-membranosus, and gracilis muscles, 
 on the inner side of the internal lateral ligament of the knee. This very strong aponeu- 
 rotic insertion represents the fascia lata on this aspect of the limb, and forms an acces- 
 sory internal lateral ligament. 
 
 From the above description, it follows that the triceps femoralis is composed of three 
 muscles and three tendons, super-imposed upon each other, viz., the rectus femoris, the 
 vastus externus, and the vastus internus. 
 
 Relations. — The long portion of the triceps, or the rectus femoris, is covered by the 
 fascia lata in its lower three fourths. Its upper part is covered by the sartorius, by the 
 anterior fibres of the glutajus medius, and by the psoas and iliacus. It covers the hip- 
 joint, the anterior circumflex vessels, and the two vasti muscles. The vasti surround 
 the femur as in a muscular sheath, and have relations with all the muscles of the thigh. 
 They are superficial in a great part of their extent : in front, they are in relation with 
 the psoas and iliacus, the rectus femoris, and the sartorius, and they lie immediately 
 under the fascia, in the triangular spaces left between these muscles : behind, they are 
 in relation with the biceps and semi-membranosus ; on the inside, with the adductors, 
 with the femoral artery, the sheath of which the vastus internus contributes to form, 
 and with the sartorius ; on the outside, with the glutaeus maximus, which glides over 
 the upper end of the vastus externus, and is separated from it by a synovial bursa ; and, 
 lastly, with the tensor vaginae femoris, and the fascia lata. It is necessary to allude 
 here to a small fleshy bundle, formed by the deepest and lowest fibres of the vastus in- 
 ternus, which is always distinct from the rest of the muscle, and is inserted into the up- 
 per part of the synovial membrane of the knee. This bundle has been regarded by Wins- 
 low as an articular muscle, intended to prevent the synovial membrane from being 
 pinched between the surfaces of the joint. 
 
 Action. — This muscle extends the leg upon the thigh ; its action is facilitated by the 
 existence of the patella, which serves to increase the angle of insertion, and which we 
 have described as a sesamoid bone, developed in the substance of the tendon. We must, 
 therefore, regard the triceps as inserted into the anterior tuberosity of the tibia, or, rath- 
 er, into tiie lower part of that tuberosity. It should be observed, that the tendon is in- 
 serted into the patella, in front of its base, and not into the base itself, in the same man- 
 ner as the ligameutum patellae is attached to the anterior surface of that bone, and not 
 to the rough mark on its posterior surface : this important arrangement increases the 
 angle at which the moving power operates. The triceps femoralis is the most powerful 
 muscle in the body, no other having such large surfaces of origin, and, consequently, so 
 great a number of fibres. By itself it supports, in a state of equilibrium, tlie entire 
 weight of the body in standing, and may be adduced as a striking example of the pre- 
 dominance of the extensors over the flexors ; it is also this muscle which raises the 
 whole trunk in progression and in the act of leaping. We cannot, therefore, be astonish- 
 ed at rupture of the patella, of its ligament, or of the common tendon, during a violent 
 contraction of this muscle, notwithstanding its disadvantageous insertion so near to the 
 fulcrum. The rectus necessarily acts with the two vasti, but it can also flex the thigh 
 upon the pelvis. The somewhat oblique direction of the tendon of the triceps down- 
 ward and iawar^, and of the ligameutum patelljff downward and outward, so that Siey 
 form an obtuse angle, open to the outside {see Jig. 126), and more especially Jliejjjfedom- 
 inance of the vastus externus over the vastus internus, sufficiently account for the oc- 
 currence of luxation of the patella>Qulw.aj:d,taiid (dr the impossibility of its beiifig dislo- 
 cated inward. 
 
 When the patella is forced inward by external violence, the contraction of the vastus 
 externus draws it back into its original position : on the other hand, the action of this 
 muscle has a tendency to displace it outward ; and when this is accomplished, the same 
 muscle keeps it in its abnormal position. Luxations of the patella, therefore, if not al- 
 together irreducible, can only be temporarily replaced ; whenever the hand ceases to re- 
 tain tlie bone in its proper place, the contraction of this muscle again dislocates it. Pro- 
 fessor Ant. Dubois has informed me of an individual whose knees were bent very much 
 inward, who could not contract the triceps femoralis with any force without dislocating 
 the patella outward. 
 
THK GRACILIS, ETC. 
 
 iM 
 
 Internal Region of the Thigh. 
 
 The muscles of the internal region of the thigh are the gracilis and the adductors, 
 among which I include the pectineus. 
 
 The Gracilis. 
 
 The gracilis (le grele interne, ou droit interne, Winslow, v,figs. 124, 125, 126) is a long, 
 straight, and slender muscle, and the most superficial of those situated on the inside of 
 .he thigh. 
 
 Attachments. — It arises from the symphysis pubis, between the pubic spine and the 
 ascending ramus of the ischium, and is inserted into the spine of the tibia. It arises by 
 some long, shining, and parallel tendinous fibres, which bind down a perpendicular fibrous 
 bundle that lies on the inner side of the line of attachment. The fleshy fibres succeed- 
 ing to these are at first parallel, and "form a broad, thin bundle ; they then converge to- 
 wards each other, so that the entire muscle resembles a much elongated isosceles tri- 
 angle. It is rounded below, and terminates in a long, thin tendon, which runs for a con- 
 siderable distance upon its posterior border, and receives all the fleshy fibres in succes- 
 sion. This tendon becomes free immediately above the knee-joint, is then situated be- 
 hind the internal condyle of the femur, turns round this process and the corresponding 
 tuberosity of the tibia, and is inserted into the spine of the last-mentioned bone, behind 
 the tendon of the sartorius, and above that of the semi-tendinosus, with both of which it 
 is united so as to form the trifid aponeurotic interlacement, denominated la patte d'aie 
 (goose's foot). 
 
 Relations. — The gracilis is covered by the femoral fascia, and slightly by the sartorius 
 at its lower part : it covers the three adductors, the inside of the knee-joint, and the in- 
 ternal lateral ligament, from which it is separated by a synovial bursa common to it and 
 the semi-tendinosus : the vena saphena interna crosses the inner surface of this muscle 
 obliquely, near its lower extremity. 
 
 Action. — It flexes the leg, and carries it slightly inward, at the same time, by means of 
 its reflection round the knee ; in this part of its action it assists the sartorius ; it also ad- 
 ducts the thigh. In the position of standing, its movable point is at the pelvis. 
 
 The Mductor Muscles of the Thigh. 
 
 There are three muscles on the inner aspect of the thigh which are called adductors ; 
 with these the older anatomists were acquainted under the collective name of the triceps 
 adductor. Modern viTiters, however, describe them either in the order of their super- 
 imposition, as the fo-st, seco7id, and third (Boyer) ; or in the order of their size, as the mid- 
 dle, small, and great adductors (Bichat). These vague denominations are the source of 
 much confusion, for the one which occupies the middle place as regards size is the first 
 as regards its position. I have therefore thought it right to modify these names, and 
 have, at the same time, included the pectineus among the adductor muscles. I consider, 
 therefore, that there are four adductors, which I shall divide into superficial and deep ; 
 the two superficial are the pectineus and the first or long adductor ; these I shall term 
 the first and second. 
 
 Superficial Adductors. — The two deep are the short and the great adductors, which I 
 shall denominate the small deep adductor and the great deep adductor. Strictly speaking, we 
 could only admit the existence of two adductors, one superficial, the other deep ; and this 
 mode of division would perhaps be preferable. 
 
 Dissection. — This is common to all the adductors. Abduct the thigh so as to render 
 these muscles tense. Make an incision through the integuments from the middle of the 
 femoral arch to the patella, and a semicircular incision at either end of this ; preserve 
 the vessels and nerves, in order to examine their relations ; tie and cut across the vena 
 sephena where it enters the femoral vein ; divide the fascia lata, and dissect the mus- 
 cles, which will then be brought into view. 
 
 The First Superficial Adductor, or Pectineus. 
 
 Tiie pectineus {pecten, the pubes) is a square muscle {w, fig. 126) situated at the upper 
 anterior and inner aspect of the thigh, on the inner side of the psoas and iliacus (c). 
 
 Attachments. — It arises (w, fig. 127) from the spine and crest of the pubes, from the trian- 
 gular surface in front of this crest, and from the lower surface of a very strong tendinous 
 and arched prolongation of Gimbernat's ligament, which is attached to the crest of the pu- 
 bes, and is continuous with the fascia covering the muscle. It is inserted (w, fig- 127) 
 below the lesser trochanter, into the ridge extending from that process to the linea as- 
 pera. With the exception of the spine of the pubes, where there are always some well- 
 marked tendinous attachments, the fleshy fibres commence directly from the several ori- 
 gins : they proceed downward, backward, and outward, and constitute a bundle, which is 
 at first flattened from before backward, and afterward from without inward .- the fibres of 
 this after a short course converge, and are inserted into the internal bifurcation of the 
 linea aspera, in part directly, and partly through the medium of an aponeurosis which oc- 
 cupies the anterior surface of the muscle. 
 
MYOLOGY. 
 
 Tig. 127. 
 
 Relations. — The pectineus is covered by the deep layer of 
 the femoral fascia, and by the femoral vessels. It covers the 
 capsular ligament of the joint, the small deep adductor, and 
 the obturator externus, from which it is separated by the ob- 
 turator vessels and nerves. Its outer border is parallel with 
 the inner border of the conjoined portions of the psoas and 
 iliacus, and is separated from them by a cellular interval, over 
 which the femoral artery passes ; so that, were it not for the 
 projection of this outer border, this vessel would be in imme- 
 diate contact with the bone. Its inner border is in relation 
 with the second superficial adductor, and is sometimes blend- 
 ed with it, except below, where it is separated by an interval 
 in which the small deep adductor may be seen. It has an im- 
 portant relation with the anterior orifice of the sub-pubic canal, 
 which corresponds with the posterior surface of the muscle. 
 When hernial protrusions, therefore, take place at the fora- 
 men ovale, the displaced parts are always covered by the pec- 
 tineus muscle. 
 
 The Second Superficial Adductor^ or Mductor 
 Longus. 
 The adductor longus of Albinus (le premier adducteur, Ba- 
 yer; le moyen adducteur, Bichat, x,fig. 126) is a flat, triangu- 
 lar muscle, situated on the same plane as the pectineus, of 
 which it seems to be a continuation, and with which it is often 
 blended above. For this reason, Vesalius made of these two 
 muscles his eighth pair of muscles of the thigh, under the 
 name of pars octava femur moventium. It is certain that there 
 is a sort of consolidation between these two muscles, and that 
 a small pectineus is always observed in conjunction with a 
 large adductor longus. 
 
 Attachments. — It arises {x, Jig. 127) from the spine of the 
 pubes, and is inserted {x) into the middle third of the linea as- 
 pera of the femur. Its origin consists of a narrow, flat ten- 
 don, which expands anteriorly, and gives origin to a thick and 
 broad fleshy belly ; this passes downward, backward, and out- 
 ward, and is inserted into the middle third of the linea aspera 
 of the femur, between the triceps femoralis in front, and the great deep adductor behind : 
 with the latter of these muscles it becomes blended at its insertions. It is attached to 
 the bone by means of two tendinous layers, between which the fleshy fibres are receiv- 
 ed. A number of foramina, intended for the perforating arteries, are observed in the neigh- 
 bourhood of this attachment. 
 
 Relations. — Its upper part lies immediately under the fascia, and it becomes gradually 
 deeper as it passes downward. It is in relation with the sartorius, from which it is sep- 
 arated by the femoral artery and veins. This relation is one of great importance, as I 
 shall hereafter have occasion to point out. 
 
 The Small Deep Adductor, or Adductor Brevis. 
 
 The adductor brevis o{ Albinus (le seconde of Boyer ; le petit of Bichat, y,fig. 127) is 
 of the same form as the preceding muscle, and is the second in the order of super-im- 
 position, but the smallest in size. It arises below the spine of the pubes on the outer 
 side of the gracilis and the inner side of the obturator externus, from a variable extent 
 of surface. The fibres proceed outward, downward, and a little backward, and form a 
 thick bundle, at first flattened from within outward, and then from before backward, 
 which increases in breadth, and terminates at the middle of the linea aspera of the femur, 
 in front of the great deep adductor, and behind the two superficial adductors, with which 
 it is blended at its insertion. 
 
 Relations. — It is covered by the superficial adductors, and it covers the great deep ad- 
 ductor, or adductor magnus. Its outer border has a relation with the obturator externus, 
 and the conjoined psoas and iliacus muscles ; its inner border is at first in contact with 
 the gracilis, and is then applied to the adductor magnus, from which it is sometimes 
 difficult to separate it. 
 
 The Great Deep Adductor, or Adductor Magnus. 
 Dissection. — In order to obtain a good view of this muscle, it is not suflicient to study 
 its anterior surface only, which is exposed after the preceding muscles have been divi- 
 ded ; its posterior surface must also be examined ; and for this purpose it is necessary 
 to remove the three muscles of the posterior region of the thigh, viz., the biceps, the 
 semi-tendinosus, and the semi-membranosus. 
 
THE ADDUCTOR MAGNUS, ETC. 277 
 
 The adductor magnus of Alhimis (le troisi^me of Boyer ; le grand of Bir.hat, z, z', figs. 
 124 to 127) is a very large, triangular muscle, extremely thick internally, where it con- 
 stitutes almost the entire substance of the inside of the thigh {fig. 127). It arises from 
 the whole extent of the ascending ramus of the ischium, from a small part of the de- 
 scending ramus of the pubes, and from the apex, i. c, the lowest portion, of the tuberos- 
 ity of the ischium. It is inserted into the whole extent of the interval between the two 
 lips of the linea aspera, and into a very prominent tubercle upon the inner condyle of the 
 femur, above the depression for the insertion of the tendon of the inner head of the gas- 
 trocnemius. Its origins, especially those from the ischium, which are the principal, can 
 only be seen on the posterior surface of the muscle (see fig. 125). They consist of ten- 
 dinous bundles, giving origin immediately to fleshy fibres, which form an extremely thick 
 mass, directed downward and outward, and presenting coarse bundles, almost as large 
 and as easily separable as those of the glutasus maximus. The muscle soon divides 
 into two portions, or, rather, into two distinct muscles, an internal and an external. 
 
 The internal portion {z,figs. 125, 127) forms the inner border of the adductor magnus, 
 the original course of which it follows. About the lower third of the thigh, its fibres 
 are received into a tendinous semi-cone, open on the outside, and terminating in a shi- 
 ning tendon, which is inserted into a well-marked tubercle on the upper and back part of 
 the internal condyle of the femur. Throughout its whole course, this tendon lies close 
 to the aponeurosis of the vastus internus. 
 
 The external portion (z',^^. 125), abandoning the primitive direction of the muscle, is 
 directed outward, and separates into thick bundles, which are inserted into the whole 
 extent of the interval between the lips of the linea aspera by means of a very large 
 aponeurosis, which is intimately united to the tendons of the other adductors, and forms 
 a series of arches (see fig. 125) for the passage of the perforating arteries. 
 
 These two divisions of the adductor magnus are separated below by the femoral ar- 
 tery and veins and their sheath, and are generally distinct for a considerable extent, and 
 sometimes entirely so. I have met with a case of this kind. That portion of the mus- 
 cle which was inserted into the internal condyle arose entirely from the apex of the tu- 
 berosity of the ischium ; while the origin of that portion which was attached to the linea 
 aspera took place from a prominence situated on the external side of that tuberosity, 
 and projecting outward from it, and also from the ascending ramus of the ischium, and 
 the descending ramus of the pubes, externally to the gracilis muscle. The superior 
 fibres {fig. 125) are horizontal, and, forming a distinct, and, as it were, a radiated bundle, 
 turn in front of the succeeding fibres, and are inserted into the line leading from the 
 great trochanter to the linea aspera, internally to the glutaeus maximus. 
 
 Relations. — The adductor magnus is covered by the superficial adductors and by the 
 small deep adductor : it covers the semi-tendinosus, the biceps, the semi-membranosus, 
 and the glutaeus maximus. Its inner border is bounded by the gracilis above, and by the 
 sartorius below: its upper border is in contact with the obturator externus ie,fig. 127) 
 on the inside, and with the quadratus femoris (i, fig. 125) more externally. Its most 
 important relation is that with the femoral artery and vein, which pass through it before 
 reaching the popliteal space. At the place where this periforation occurs we observe a 
 tendinous arch, or, rather, canal, into which the fleshy fibres are inserted ; and so, also, 
 where the perforating arteries pass through this muscle. 
 
 Action of the Adductor Muscles. — ^The muscles we have just described are both flexors 
 and rotators outward ; but their principal office, as their name indicates, is to perform 
 adduction, a very energetic movement, as might be anticipated from the strength of the 
 muscles concerned in its production. We have seen, indeed, that the line of origin ex- 
 tends from the ilio-pectineal eminence as far as and including the tuberosity of the ischi- 
 um, and that the insertions occupy the entire length of the linea aspera, the two branch- 
 es of its superior bifurcation, and the inner condyle of the femur. These muscles are 
 powerfully exerted during equestrian exercise ; it is by their means that the horse is 
 firmly grasped between the knees. The two superficial adductors and the adductor bre- 
 vis are also flexors, because their insertions are posterior to their origins. All the ad- 
 ductors are, as it were, rolled around the femur during rotation inward. 
 
 MUSCLES OF THE LEG. 
 
 The Tibialis Anticus. — Extensor Communis Digitorum. — Extensor Proprius Pollicis. — Pe- 
 roneus Longus and Brevis. — Gastrocnemius, Plantarus, and Soleus. — Popliteus. — Titia- 
 lis Posticus. — Flexor Longus Pollicis. 
 
 The muscles of the leg may be divided into those of the anterior, those of the exter- 
 nal, and those of the posterior regions. 
 
 Muscles of the Anterior Region of the Leg. 
 The muscles of the anterior region of the leg are the tibialis, the extensor communis 
 digitorum. and the extensor proprius pollicis pedis. The anterior peroneus, or peroneus 
 
ms 
 
 MYOLOGY. 
 
 tertius, wlien it exists, is nothing more than an accessory fasciculus of the extensor 
 communis. 
 
 The Tibialis Anticus. 
 Dissection. — ^Make a vertical incision through the skin from the anterior tuberosity of 
 
 Fig.l^ 
 
 the tibia to the middle of the inner border of the foot ; dissect 
 back the two flaps of skin, and expose the fascia of the leg ; di- 
 vide this fascia vertically, commencing from the middle of the 
 leg, and terminating at the lower end of the tibia, taking care to 
 preserve the annular ligament ; prolong the dissection and sep- 
 aration of the fascia as far upward as possible ; lastly, remove 
 the fascia on the dorsum of the foot, which covers inferiorly the 
 tendon of the tibialis anticus. 
 
 The tibialis anticus {a, fig. 128) is a long, thick, prismatic, and 
 triangular muscle, placed superficially along the outer side of the 
 tibia. 
 
 Attachments. — It arises from the crest which bounds the ante- 
 rior tuberosity of the tibia on the outside, and from the tubercle 
 terminating this crest above ; from the external tuberosity of the 
 tibia, and the superior two thirds of its external surface, which 
 presents a depression proportioned to the strength of the muscle ; 
 from all that portion of the interosseous ligament situated to the 
 inner side of the anterior tibial vessels and nerves ; from the 
 deep surface of the fascia of the leg ; and, lastly, from a tendi- 
 nous septum intervening between this muscle and the extensor 
 communis digitorum. It is inserted into the tubercle on the first 
 or internal cuneiform bone, and sends oflT a tendinous expansion 
 to the first metatarsal bone. 
 
 It arises from the internal surface of an osteo-fibrous quadran- 
 gular pyramid formed by the tibia, the fascia of the leg, the inter- 
 osseous ligament, and the inter-muscular septum ; from these 
 points the fleshy fibres proceed vertically downward, and termi- 
 nate around a tendon which commences in the substance of the 
 muscle above its middle third ; the anterior fibres cease at the 
 lower third of the muscle, the posterior accompany the tendon 
 to the point where it passes under the dorsal ligament of tlie in- 
 step (seen in fig. 128). As soon as the tendon appears on the 
 anterior border of the muscle, it is deflected forward in a similar 
 manner to the external surface of the tibia, and follows the same 
 oblique course, after having left the common sheath of all the 
 muscles of the anterior region of the leg. Another sheath, which 
 is nothing more than the condensed dorsal fascia of the foot, re- 
 ceives the tendon at the point where it passes vertically downward, to be inserted into 
 the tubercle of the first cuneiform bone. 
 
 Relations. — The tibialis anticus is covered by the fascia of the leg asad the dorsal fascia 
 of the foot ; on the inside it is in relation with the external surface of the tibia ; on the 
 outside, at first with the extensor communis digitorum, and then with the extensor pro- 
 prius pollicis, from which it is separated behind by the anterior tibial vessels and nerves. 
 Action. — It flexes the foot upon the leg ; and, from tlie obliquity of its tendon, it raises 
 the internal border of the foot, and, consequently, produces that sort of rotation inward 
 at the articulation of the two rows of the tarsus which we have already alluded to. It 
 tends, also, to adduct the ankle-joint, and is, consequently, opposed to dislocation out- 
 ward. The absence of a proper sheath for this muscle explains the considerable pro- 
 jection formed by its tendon during contraction, which may serve as a guide to the pre- 
 liminary incisions in ligature of the dorsal artery of the foot. Spigelius called this mus- 
 cle the musculus catencE, because fetters applied around the ankles of criminals press 
 chiefly upon the projection formed by its tendon. 
 
 The Extensor Longus Digitorum Pedis, and the Peroneus Tertius vel Anticus. 
 
 Dissection. — Remove the fascia of the leg and the dorsal fascia of the foot. 
 
 This is an elongated, semi-penniforra, and reflected muscle {b c, fig. 128), flattened 
 from within outward, single above, and divided into four or five tendons below. 
 
 Attachments. — It arises from the external tuberosity of the tibia, on the outer side of 
 the tibialis anticus ; from the whole of the internal surface of the fibula in front of the 
 interosseous ligament, and slightly from that ligament ; from the upper part of the fascia 
 of the leg, and from the tendinous septa interposed between this muscle and the tibialis 
 anticus within, and the peroneus longus and brevis without. It is inserted into the sec- 
 ond and third phalanges of the last four toes. 
 
 From these numerous origins the fleshy fibres proceed in different directions ; the su- 
 
THE EXTENSOR PEOPRIUS POLLICIS. "^9 
 
 perior vertically downward, the rest obliquely downward and forward, the lowest being 
 the most oblique ; they all terminate around a tendon, which appears upon the anterior 
 border of the muscle below the upper third of the leg. This tendon soon divides into 
 two portions : one internal, and itself subdivided into three tendons for the second, third, 
 and fourth toes ; the other external, and generally split into two tendons, one of which 
 is intended for the fifth toe, while the other is fixed to the posterior extremity of the cor- 
 responding metatarsal bone. This last subdivision is often wanting : it is but imperfect- 
 ly separated from the fasciculus belonging to the fifth toe, to which it almost edways 
 sends off an accessory tendon : it has been generally described as a separate muscle, 
 under the name of the peroneus tertius or anticus {c,Jig. 128). I have thought it right, 
 however, to connect this muscle with the extensor longus digitorum (i), from which it 
 can be so imperfectly separated that it has been designated by Cowper, pars extensoris 
 digitorum pedis longi ; and by Morgagni, quintus tendo extensoris longi digitormn pedis. 
 
 The extensor communis is directed vertically as far as the ankle-joint, where it enters 
 a sheath conmion to it and the flexor proprius poUicis, is next reflected under this sheath, 
 becomes horizontal, passes obliquely inward and opposite the tarsus, is received into a 
 much stronger proper sheath, after leaving which the five tendons separate so as to cov- 
 er the dorsd surface of the metatarsal bone of the toes, to which they correspond. In 
 this course they cross the extensor brevis digitorum at a very acute angle, reach the 
 dorsal surface of the metatarsal phalangal articulations, apply themselves to the inner 
 edges of the corresponding tendons of the extensor brevis, receive some expansions from 
 the interossei and lumbricales, and are arranged in precisely the same manner as the ex- 
 tensor tendons of the fingers, forming a fibrous sheath on the dorsal surface of the first 
 phalanx of the toes ; and like these, having arrived at the articulations of the first with 
 the second phalanges, each divides into three portions : one median, attached to the pos- 
 terior extremity of the second phalanx ; and two lateral, which unite upon the dorsal sur- 
 face of the second phalanx, to be inserted into the posterior extremity of the third. 
 
 Relations. — Internally this muscle is in relation with the tibialis anticus, from which 
 it is soon separated by the extensor proprius pollicis, and externally with the peroneus 
 longus and brevis. It is covered by the fascia of the leg and foot, and it covers the fibula, 
 the interosseous ligament, the ankle-joint, the extensor brevis digitorum, which separ- 
 ates it from the tarsus and metatarsus ; lastly, it covers the toes. 
 
 Action. — As in all reflected muscles, we must suppose the power to be exerted imrne- 
 diately after its reflection, and in the direction of the reflected portion : in this way, it will 
 be seen that it extends the third phalanges upon the second, and the second upon the 
 first ; and having produced this effect, it flexes the foot upon the leg. From its obliqui- 
 ty, it also draws the toes outward, and turns the sole of the foot inward. 
 
 The Extensor Proprius Pollicis. 
 
 The extensor proprius pollicis {d,fig. 128) is an elongated, thin, flat muscle, placed in 
 front of the leg, betwisen the extensor longus digitorum and the tibialis anticus. 
 
 Attachments. — It arises from the interned surface of the fibula, and slightly from the 
 adjacent part of the interosseous ligament, within and behind the extensor communis 
 This origin is situated at variable heights, but commonly not above the middle third 
 of the leg. It is inserted into the posterior extremity of the second phalanx of the great 
 toe. The fleshy fibres arise directly from the fibula and the interosseous ligeiment, and 
 proceed at first vertically around, and then obliquely behind a tendon, which occupies the 
 anterior border of the muscle, and to which the fleshy fibres are all attached in a sloping 
 manner, like the barbs of a feather, as far down as below the proper sheath formed for 
 it at the tarsus. From thence the tendon is reflected at a right angle, proceeds oblique- 
 ly and horizontally forward and inward upon the dorsum of the foot, passes along the 
 dorsal surface of the first metatarsal bone and first phalanx of the great toe, to the latter 
 of which it gives off a prolongation on each side, and is then inserted into the second 
 phalanx. 
 
 Relations. — Internally, it is in relation with the tibialis anticus, from which it is sep 
 arated behind by the anterior tibial nerve and vessels ; and externally, with the extensor 
 longus digitorum. Its anterior border, at first concealed between the preceding muscles, 
 is soon situated immediately beneath the fascia, and during its contraction forms a pro- 
 jection, which it is important to know, because it serves as a guide in searching for the 
 dorsal artery of the foot, which will always be found on the outer margin of the tendon : 
 it may be called the muscle of the arteria dorsalis pedis. In the foot it crosses superfi- 
 cially to the extensor brevis digitorum. 
 
 Action. — It extends the second phalanx of the great toe upon the first, and that upon 
 the metatarsus ; when this is accomplished, it flexes the foot upon the leg. In conse- 
 quence of its obliquity, it tends, like the preceding muscle, to turn the toes outward, and 
 slightly to elevate the inner border of the foot. 
 
 External Region of the Leg. 
 In this region are found the peroneus longus and peroneus brevis muscles. 
 
9^ MYOLOGY. 
 
 The Peroneus Longus. «k-«.'i 
 
 Dissection. — This is common to both muscles. Remove the skin on the outer side of 
 the leg ; make a vertical incision through the fascia ; reflect the two flaps, in order to ar- 
 rive at the tendinous septa dividing the peronei from the muscles of both the anterior 
 and posterior regions of the leg. To expose these muscles in the foot, remove the outer 
 portion of its dorsal fascia, and divide obliquely inward and forward all the muscles of 
 the pkntar region, from the groove of the cuboid to the posterior extremity of the first 
 metatarsal bone. 
 
 The peroneus longus {e,figs. 128 to 130) is a long, thick muscle, prismatic and trian- 
 gular at its upper part, and superficially situated on the outer side of the leg (peroneus 
 primus, Spigelius). 
 
 Attachments. — It arises externally from the outer and anterior part of the head of the 
 fibula ; from a small portion of the contiguous part of the external tuberosity of the tibia ; 
 from the upper third of the external surface of the fibula ; and from the anterior and pos- 
 terior borders of that bone, by means of very strong tendinous septa, interposed between 
 it and the anterior and posterior muscles of the leg ; lastly, from the fascia of the leg 
 superiorly. It is imerted into the posterior extremity of the first metatarsal bone, on the 
 outer side of which a process exists for this purpose. 
 
 From these very numerous origins, the fleshy fibres proceed vertically and form a bun- 
 dle {e,fig. 130), thick above, thin and flat below, and terminating in a tendon which is at 
 first concealed in the substance of the muscle, but appears in the form of a band on its 
 outer side, a little above the middle of the fibula, and becomes narrower and thicker as it 
 proceeds. Tlie tendon soon leaves the fleshy fibres, and accompanies the external sur- 
 face of the fibula as it turns backward (peroneus posticus, Riol), then passes behind the 
 external malleolus in a groove common to it and to the peroneus brevis, and is reflected 
 forward and downward to the outer side of the os calcis, upon which it is held by a sep- 
 arate sheath. Having reached the outer side of the cuboid bone, it is again reflected, 
 enters a groove running obliquely inward and forward upon the lower surface of that 
 bone {e,figs. 132, 133), where it is retained by a very strong and compact sheath, and 
 continues its oblique course, without any deviation, along the lower surface of the tarsal 
 bones ; as far as the posterior extremity of the first metatarsal bone. In this way the 
 tendon of the peroneus longus undergoes a double reflection : first, behind the external 
 malleolus, in which situation a thickening or knot is often seen ; and, secondly, at the 
 cuboid bone, opposite which a sesamoid bone almost always exists. There are also 
 three? fibrous sheaths, and three synovial membranes belonging to this tendon, one be- 
 hind the external malleolus, one upon the outside of the os calcis, and a third under the 
 cuboid bone. 
 
 Relatioiis. — In the leg, the peroneus longus is covered by the skin and the fascia of the 
 leg : it covers the peroneus brevis. In front, a tendinous septum intervenes between it 
 and the extensor longus digitorum : behind, another inter-muscular septum exists between 
 it and the soleus above, and the flexor proprius below. On the outside of the foot, its 
 tendon corresponds to the skin externally, and to the os calcis internally. In the plantar 
 region, it is covered below by the entire thickness of the soft parts, and corresponds 
 above to the inferior tarsal ligaments. 
 
 Action. — As we have already so frequently observed, a reflected muscle acts as if the 
 power were applied at the point of reflection. In this way, by transferring the power to 
 the outer end of the groove on the cuboid bone, we shall find that the foot is abducted, 
 or, rather, rotated outward by this muscle ; by next supposing the power to act from the 
 other point of reflection, i. e., from behind the external malleolus, we may observe that 
 the foot is extended upon the leg, and its outer border turned upward. In this move- 
 ment, the lower end of the external articular surface of the astragalus tends to carry the 
 external malleolus outward, and to increase the curvature of the fibula, which is some- 
 times fractured in consequence. It may be easily conceived that if the fibula be frac- 
 tured, the contraction of this muscle will no longer be counteracted, and accordingly 
 will turn the sole of the foot outward, and may luxate the astragalus inward. This is 
 the mechanism of luxation of the foot occurring after fracture of the fibula, the only 
 species of lateral dislocation of this part which has ever been observed.* 
 
 The Peroneus Brevis. 
 
 The peroneus brevis o{ Albinus (peroneus secundus, Spigel ; le petit peronier, Wins- 
 tmB,f,figs. 129, 130) is a flat, penniform, and reflected muscle, smaller and shorter than 
 the preceding, beneath which it lies. 
 
 Attachments. — It arises from the lower half, sometimes from the lower two thirds of 
 the external surface of the fibula, which is more or less excavated for this purpose ; from 
 the anterior and posterior borders of the same bone, and from the tendinous septa exist- 
 ing between this muscle and those of the anterior and posterior regions of the leg. 
 
 It is inserted into the posterior extremity of the fifth metatarsal bone, and sometimes 
 
 * See the admirable memoir by M. Dupuytren, on fracture of the fibula. 
 
THE GASTROCNEMIUS. 
 
 2B1 
 
 CYcn, by a tendinous expansion, into the fourth metatarsal bone ; it often gives off a pro- 
 longation to the extensor tendon of the httle toe. 
 
 The fleshy fibres proceed successively from their different origins to the internal sur- 
 face and edges of a tendon, situated upon the outer surface of the muscle ; the bundle 
 which they form gradually increases in size, and then diminishes, is at first penniform, 
 and afterward semi-penniform, and accompanies the tendon as far as the fibrous sheath 
 behind the external malleolus : after leaving the sheath, the tendon enters another, prop- 
 er to itself, upon the outer side of the os calcis, above that for the tendon of the peroneus 
 longus, and passes somewhat obliquely downward and forward, to be inserted into the 
 base of the fifth metatarsal bone. 
 
 Relations. — It is covered by the peroneus longus, and covers the fibula and the outer 
 side of the os calcis. It is, therefore, only in comparison with the peroneus longus that 
 Riolanus and others have called this muscle the anterior peroneus. 
 
 Action. — The same as that of the peroneus longus, with the exception of that of its 
 subtarsal portion. Thus, supposing the power to be applied at the external malleolus, 
 we have extension of the fifth metatarsal bone upon the cuboid ; extension and rotation 
 inward of the second row of the tarsus upon the first ; rotation of the calcaneum upon 
 the astragalus ; extension, and a tendency to abduction of the entire foot, which is 
 therefore considerably everted when the fibula is fractured. 
 
 PosTEKioK Region. 
 There are two layers in this region : one superficial, formed by the gastrocnemius and 
 soleus (or triceps suralis) and the plantaris ; the other deep, consisting of the popliteus, 
 the tibialis posticus, the flexor longus digitorum, and the flexor longus pollicis. 
 
 The Gastrocnemius and Soleus, or Triceps Suralis, and the Plantaris. 
 Dissection. — Make a vertical incision from the upper part of the popliteal space to the 
 heel ; at right angles to this, above, make another horizontal and semicircular incision, 
 embracing the back part of the thigh ; divide and dissect the fascia of the leg. The gas- 
 trocnemii will then be exposed, and must be dissected very carefully at their origins. In 
 order to study the structure and attachments of these muscles properly, they must be 
 cut transversely in the middle, and the superior half turned upward. In dividing the 
 outer head of the gastrocnemius, be careful not to cut the plantaris, which seems to be 
 merely a small fasciculus detached from that muscle. The soleus is exposed by simply 
 removing the gastrocnemius ; but, in order to study its structure and attachments, it 
 
 must be divided vertically from behind forward at the side of a 
 median tendinous raph^, and the fibres which conceal this median 
 aponeurotic lamina of the muscle must be scraped away. From 
 this division we have a fibular and a tibial portion of the soleus. 
 
 The gastrocnemius (g g) and the soleus (i i',Jig. 129) together 
 constitute a very powerful triceps muscle (musculus surae. Seem.), 
 which, by itself, forms the fleshy part of the leg, commonly called 
 the calf The great development of these muscles is one of the most 
 marked characteristics of the muscular apparatus of the human sub- 
 ject, and is connected with his destination for the erect position. 
 The three portions of the triceps suralis are united together below 
 in a common tendinous insertion, constituting the tendo Achillis {t, 
 Jig. 129), but are divided above into two very distinct planes : one, 
 anterior or deep, formed by the soleus ; the other, posterior or su- 
 perficial, consisting of the two heads of the gastrocnemius. We 
 shall describe these in succession. 
 
 Gastrocnemius. 
 
 The gastrocnemius, from yaarrip, a belly, and Kv^firj, the leg (ge- 
 mellus, Albinus ; primus pedem moventium, cum secundo, Vcsalt- 
 us), is the most superficial muscle on the back of the leg : it con- 
 sists of two heads above {g g',fig. 129), but forms a single fleshy 
 belly, which is thick and flattened from before backward. 
 
 It arises from the condyle of the femur by two perfectly distinct 
 but similar heads, viz., an outer or smaller, called the gemellus ex- 
 ternus {g), and an inner or larger, named the gemellus internus (g-')- 
 They take their origin from the bone, by two very strong and flat 
 tendons, which are attached on the outer side, and behind the con- 
 dyle of the femur, to two well-marked digital impressions, that for 
 the outer head being situated above a much deeper impression foi 
 the popliteus muscle, and that for the inner head inmiediately be 
 hind the tubercle into which the adductor magnus is inserted, so 
 that the inner head is situated upon a plane a little posterior to that 
 of the outer head. They also arise, by tendinous fasciculi, from 
 
 Nn 
 
 Fig. 139. 
 
S82 MYOLOGY. 
 
 the rough triangular surfaces surrounding the digital impression, and terminating at the 
 inferior bifurcation of the linea aspera. Each tendon of origin (that for the inner being 
 much larger than that for the outer head) expands into an aponeurosis upon the posteri- 
 or surface of that portion of the muscle to which it belongs. The aponeurotic expansion 
 of the inner head is, moreover, thicker and longer than the other, and embraces the inner 
 border of that part of the muscle, like a tendinous semi-cone. The fleshy fibres arise 
 from the anterior surface of these tendinous expansions, and are disposed in the follow- 
 ing manner : those in the middle, which are few in number, are strengthened by fleshy 
 fibres proceeding from the rough projections of the bifurcation of the linea aspera, pass 
 inward and downward, and are united together like the limbs of the letter V opening up- 
 ward, upon a median raphe, which consists either of a simple thickening of the termina- 
 ting aponeurosis, or of a small tendinous septum : the other fibres, constituting almost 
 the entire muscle, arise from the anterior surface of the tendons of origin, and from the 
 aponeurosis in which they terminate, and proceed vertically downward to the back of an- 
 other very dense aponeurotic expansion, which covers the whole anterior surface of the 
 muscle. This last aponeurosis commences above by two very distinct portions ; at first 
 it is of equal breadth with the muscle, then becomes narrower and thickened, and, finally, 
 closely united with the terminal tendon of the soleus. At the lower part of the calf the 
 fleshy fibres terminate suddenly upon the posterior surface of this aponeurosis, forming 
 a V opening downward. Although the two portions of the gastrocnemius become inti- 
 mately united shortly after their origin, they are not confounded together, and the inter- 
 nal portion forms on the inside of the tibia the greatest part of the fleshy mass called the 
 calf of the leg. 
 
 Relations. — The gastrocnemius is covered by the fascia of the leg, and it covers and 
 adheres intimately to the capsular ligament, which envelops the back part of the con- 
 dyles of the femur. It is also in relation with the popliteus and the soleus. 
 
 The tendon of the inner head corresponds to the posterior surface of the internal con- 
 dyle ; that of the outer head to the outer side of the external condyle. We often find 
 at the upper part of the tendon of each head, but most commonly in the substance of 
 that of the outer head, a sesamoid bone, that glides upon the back of the condyle, and 
 belongs to the sort of fibrous capsule or hood by which the back of each condyle is cov- 
 ered. (Vide Syndesmology, Articulation of the Knee.) 
 
 The Plantaris. 
 
 This little muscle (le plantaire grele, 1 1', Jig. 129) should be regarded as an accessory 
 of the outer head of the gastrocnemius, or, rather, as a rudimentary muscle in the hu- 
 man subject. Its small fusiform, fleshy belly, varying much in size, is found beneath the 
 outer head of the gastrocnemius. 
 
 It arises {I) from the fibrous capsule covering the external condyle, and sometimes from 
 the lower part of the external bifurcation of the linea aspera. From these points, it pass- 
 es obUquely downward and inward, and after a course of from two inches and a half to 
 three inches, ends in a long, flat, and slender tendon, which is at first situated between 
 the gastrocnemius and soleus, and afterward (/') lies parallel with the inner edge of the 
 tendo Achillis, and is inserted into the os calcis, either at the side, or in front of that ten- 
 don. Sometimes, however, it is lost in the sub-cutaneous adipose tissue. This muscle, 
 which is often wanting, is occasionally double.* 
 
 The Soleus. 
 
 The soleus (partly seen at i i',fig. 129) is so called because it has been compared to 
 the fish called a sole, or to the sole of a shoe. 
 
 Attachments. — It arises from the fibula and tibia, and is inserted into the os calcis. Its 
 fibular origins (i) consist, first, of a tendon attached behind, and on the inner side of the 
 head of that bone ; this tendon is extremely strong, especially on the inside, opposite a 
 process existing on the fibula for its attachment ; it is prolonged within the substance, 
 Snd along the anterior surface of the muscle : and, secondly, of some tendinous fibres 
 attached to the upper half of the external border of the fibula, and the upper third of the 
 posterior surface of the same bone. 
 
 The tibial origins {i') take place from the oblique line on the posterior surface of the 
 tibia below the popliteus, and from the contiguous portion of the aponeurotic expansion 
 of that muscle ; from an aponeurosis which arises from the middle third of the inner 
 border of the tibia, and is prolonged upon the anterior surface, within the substance of 
 the muscle ; and, lastly, by a few fleshy fibres from a tendinous arch extending between 
 the head of the fibula and the oblique line on the posterior surface of the tibia. From 
 these diflferent origins, the fleshy fibres pass in different directions to the anterior sur- 
 face and edge of an aponeurosis, which covers the posterior surface of the muscle, be- 
 comes narrower and thickened as it proceeds downward, unites with the terminal ten- 
 don of the gastrocnemius about the middle third of the leg, and is soon blended with it 
 to form the tendo Achiljis. 
 
 * Fourcroy, in his sixth memoir upon the liursce mucosa;, states that the plantaris, whose tendon, according 
 to Albinus, is received into a groove along^ the inner border of the tendo Achillis, is the tensor muscle of the 
 synovial capsule of that tendon. This is an error. 
 
THE POPHTEUS. 
 
 In order to study accurately the structure of the soleus, divide it longitudinally at the 
 aide of tlie raphes or tendinous septum existing in the middle of the lower half of this 
 muscle, and then, by scraping off some of the fleshy fibres, it will be seen that a dense, 
 fibrous septum given off by the terminal aponeurosis, separates the muscle into two equal 
 halves, and forms with that aponeurosis two tendinous semi-cones, in the interior of 
 which the fleshy fibres are received. It will now be understood why Douglas, who had 
 designated the gastrocnemius the two external and superficial heads of the great extensor 
 of the tarsus, should call the soleus the two internal and deep heads of the same muscle 
 There are, in fact, two principal aponeuroses of origin, and two hollow tendons of insei- 
 tion ; each aponeurosis of origin covers almost the entire anterior surface of tlie corre- 
 sponding half of the muscle. 
 
 Relations. — It is covered by the gastrocnemius, which projects beyond it on both sides, 
 but especially on the inner side, and from which it is separated by the plantaris. It is 
 thickest immediately below the largest part or belly of the inner portion of the gastroc- 
 nemius, and, consequently, it prolongs the swelling of the calf downward. It covers the 
 muscles of the deep layer, viz., the flexor communis digitorum, the flexor proprius polli- 
 cis, and the tibialis posticus ; it also covers the posterior tibial and the fibular vessels 
 and nerves. 
 
 The Tendo Achillis. — ^The tendo Achillis {I, figs. 129, 130) results from the union of the 
 tendons of the gastrocnemius, plantaris, and soleus. It is formed in the following man- 
 ner : the terminal aponeurosis of the gastrocnemius, shortly after leaving the Ik f<liy 
 fibres, is intimately united to that of the soleus, which still continues to receive fleshy 
 fibres upon its anterior surface and its edges, and gradually becoming narrower, is soon 
 joined by the antero-posterior septum of this muscle. All these tendinous fibres are col- 
 lected together to form the strongest and largest tendon in the body, known by the name 
 of the tendo Achillis, which, after a course of about an inch and a half or two inches, 
 glides over the smooth surface presented by the superior two thirds of the back of the 
 OS calcis, with the intervention of a synovial bursa, and is expanded a little, in order to 
 be inserted into the rough surface on the lower part of the same bone. 
 
 Action of the Gacirocnemius and Soleus. — These muscles extend the foot upon the leg. 
 In no other part of the body do we find so advantageous an arrangement for an immense 
 development of power. 1. These muscles are very large, and particularly remarkable for 
 the number of their fleshy fibres, in which respect they exceed all other muscles in the 
 body. 2. The mode of insertion is nowhere else so favourable, for it is absolutely per- 
 pendicular. 3. We have here a lever of the second order, in which the fulcrum is at the 
 ball of the toes, the resistance in the middle of the foot, being represented by the weight 
 of the body resting upon the ankle-joint, and the _power at the extremity of the heel (see 
 fig. 104). The length of that portion of the lever which projects behind the joint varies 
 much in different individuals ; it scarcely exists in the peculiar malformation denominated 
 flat-foot. These muscles are the principal agents in walking and leaping ; they raise 
 the weight of the whole body, even when loaded with heavy burdens. Hence it is not 
 surprising, that occasionally an energetic contraction of these muscles may rupture the 
 tendo Achillis, or fracture the os calcis. Frequent exercise appears to be necessary for 
 these muscles ; for when they remain inactive, they become atrophied, and are speedily 
 affected with fatty degeneration. The action of the soleus, which reaches only from the 
 leg to the heel, is limited to extension of the foot ; but the gastrocnemius, which is at- 
 tached to the femur, after having extended the foot, can flex the leg upon the thigh ; but, 
 from its proximity to the fulcrum, this last action is very slight. When the foot is fixed, 
 as, for example, in standing, the soleus acts upon the leg, and tends to prevent one from 
 falling forward, to which there is a constant tendency from the weight of the body ; the 
 action of the gastrocnemius, on the contrary, is to flex the thigh, and in this respect it 
 is altogether independent of the soleus. 
 
 The plantaris can only be regarded as rudimentary in man ; in the lower animals it 
 is a tensor of the plantar fascia ; it has been, as it were, cut short in man, in conse- 
 quence of his destination for the erect position. Sometimes, as we have already stated, 
 it is lost upon the fatty tissue covering the os calcis. 
 
 The Popliteus. 
 
 This is a small, triangular, and very thin muscle {m,fig. 130), situated in the poplitea? 
 space. 
 
 It arises from a deep fossa, resembling a groove running from behind forward, on the 
 back of the external condyle of the femur, below the origin of the outer head of the gas- 
 trocnemius. It is inserted into the entire extent of the triangular surface, on the upper 
 part of the posterior aspect of the tibia. 
 
 It arises by a very strong tendon, which bears no proportion to the diminutive size 
 of the muscle. This tendon, at first concealed by the external lateral ligament, contain- 
 ed, as it were, in the cavity of the joint, and completely enveloped by the synovial mem- 
 brane, passes obliquely behind the articulation, and, after extending for about one inch, 
 
284 
 
 MYOLOGY. 
 
 divides, like the tendon of the obturator internus, into four or five small diverging bun- 
 IHg. 130. dl^s, which soon surround the fleshy fibres on all sides. The lat- 
 
 ter then become attached in succession to the triangular surface 
 of the tibia, the lowest being the longest and the most oblique. 
 The superficial fibres are inserted into a tendinous expansion from 
 the semi-membranosus, which covers the posterior surface of the 
 popliteus muscle, and forms a very strong sheath for it. 
 
 Relations. — It is covered by the gastrocnemius and the plantaris, 
 from which it is separated by the popliteal vessels, and the inter- 
 nal popliteal branch of the sciatic nerve. It covers the tibio-fibu- 
 lar articulations and the back of the tibia. 
 
 Action. — It flexes the leg upon the thigh, and, at the same time, 
 rotates it inward (oblique movens tibiam, Spigelius). In this last 
 respect it antagonizes the biceps. 
 
 The Tibialis Posticus. 
 
 Dissection. — Remove the gastrocnemius and soleus ; separate 
 the tibialis posticus from the flexor longus digitorum, which par- 
 tially covers it ; carefully remove from the posterior surface of the 
 tibialis posticus a very broad aponeurosis, together with a portion 
 of the long flexor of the toes, which arises from the posterior sur- 
 face of that aponeurosis ; completely separate the tibialis posticus 
 from the interosseous ligament, and the adjacent portions of the 
 tibia and fibula ; lastly, be careful to preserve the tendinous expan- 
 sions always given oflT by this muscle to the fourth and fifth meta- 
 tarsal bones. 
 
 The tibialis jposticus {n,fig. 130) is the most deeply seated of all 
 the muscles on the back of the leg ; it is very thick, and occupies 
 the whole depth of the excavation between the tibia, fibula, and 
 interosseous ligament. 
 
 Attachments. — It arises from the tibia, the fibula, and the interos- 
 seous ligament, and is inserted into the scaphoid bone. Its tibial 
 and fibular origins form a bifurcation for the passage of the poste- 
 rior tibicd artery. Its tibial attachment takes place on the oblique 
 line situated below the popliteus, soieus, and flexor longus digitorum. Its fibular origin 
 is from the inner border of that bone, below the soleus, and from all that portion of its 
 inner surface which is behind the interosseous ligament. It also arises from the entire 
 posterior surface of this ligament. Lastly, a few fibres take their origin from the deep 
 surface of an aponeurosis which separates the deep from the superficial layer of muscles, 
 and from the tendinous septa interposed between this muscle itself and the flexor lon- 
 gus digitorum on the inside, and the flexor proprius pollicis on the outside. From these 
 numerous origins the fleshy fibres proceed vertically downward, around a tendon which 
 may be distinguished near the upper extremity of the muscle, under the form of a ten- 
 dinous sheaf, which afterward appears along its posterior border, and receives the fleshy 
 fibres on its anterior surface, like the barbs of a feather upon the shaft. This tendon, 
 however, is nothing more than the thickened posterior edge of an aponeurosis occupy- 
 ing the entire substance of the muscle from before backward, and receiving the fleshy 
 fibres upon its two lateral surfaces as far down as opposite the internal malleolus. The 
 thick tendon resulting from the union of these aponeurotic fibres then becomes free, and 
 enters a proper sheath on the outer side of that belonging to the tendon of the flexor longus 
 digitorum, in front of which it then passes behind the internal malleolus, where it is also 
 enclosed in a separate sheath {n,fig. 129). On the inner side of the internal lateral lig- 
 ament of the ankle, and below the lower calcaneo-scaphoid ligament, it enters another 
 sheath, and is finally inserted {n,fig. 133) into the tubercle of the scaphoid bone, a very 
 thick sesamoid bone existing near its insertion. In some subjects this sesamoid bone 
 is found at the point of insertion ; in others it is situated opposite the calcaneo-scaphoid 
 ligament. Besides this, the tendon of the tibialis posticus gives off a very strong ex- 
 pansion to the first cuneiform bone, and on the outside an oblique expansion to the sec- 
 ond and third cuneiform bones, and even to the third or fourth metatarsal bones. 
 
 Relations. — It is covered by the flexor longus digitorum, slightly by the flexor proprius 
 pollicis, and entirely by the soleus : it covers the interosseous ligament and the adjacent 
 parts of the tibia and fibula. 
 
 Action. — The tibialis posticus extends the foot upon the leg. As it is a reflected mus- 
 cle, all the fibres must be considered as acting from the point of reflection that is be- 
 hind the inner ankle. It is evident, then, that this muscle extends the foot, both by its 
 action upon the astragalo-scaphoid articulation, and also by that upon the ankle-joint. 
 It also tends to turn the sole of the foot inward ; and, consequently, it co-operates with 
 the tibialis anticus in this respect, and antagonizes the peroneus longus and brevis. It 
 may also be understood why some persons, in whom the tendo Achillis has been cut oi 
 
THE FLEXOR LONGUS POLLICIS. 2l8^' 
 
 ruptured, are yet capable of walking, and why the foot can in all cases be extended after 
 this accident ; but under these circumstances the lever formed by the foot is changed, 
 and the power represented by the tibialis posticus is applied between the fulcrum and 
 the resistance ; so that we have, then, a lever of the third, not of the second order, as 
 when the tendo Achillis is uninjured. 
 
 The Flexor Longus Digitorum Pedis. 
 
 This is a penniform, elongated, and reflected muscle {o,figs. 130, 132), situated along 
 the posterior surface of the tibia and in the sole of the foot ; it is the most internal mus- 
 cle of the deep layer, is flattened from before backward, and terminates below in four 
 tendons. 
 
 Attachments. — It arises from the tibia, and is inserted into the last phalanges of the last 
 four toes. It arises from the oblique line of the tibia, below the popliteus and the sole- 
 us, and from the middle three fifths of the posterior surface of the same bone. Some 
 fibres also proceed from the tendinous septum intervening between it and the tibialis 
 posticus. From these different origins the fleshy fibres proceed obliquely backward 
 and downward, to the anterior surface and edges of a tendon which commences near 
 the upper end of the muscle, and gradually disengages itself from the fleshy fibres, being 
 accompanied by them anteriorly as far as the internal malleolus. It passes behind this 
 projection in the same sheath as the tendon of the tibialis posticus, from which it is sep- 
 arated by a fibrous septum ; it soon leaves that tendon, passing to its outer or fibular 
 side (o, fig. 129), and is then reflected at an obtuse angle upon the internal malleolus. 
 It now becomes horizontal, and is buried under the astragalus and the small anterior 
 tubercle of the os calcis, where it is contained in a proper sheath. Having thus reached 
 the sole of the foot (o, figs. 131, 132), it passes obliquely outward and forward, crosses 
 under the tendon of the flexor longus pollicis at a very acute angle, receives from it a 
 strong tendinous communication, and at the same time becoming expanded, is joined by 
 its accessory muscle, and finally divides into four tendons for the last four toes. The 
 tendon for the second toe proceeds directly forward. The tendons for the other toes in 
 succession pass more and more obliquely. Having reached the metatarso-phalangal ar- 
 ticulations, these tendons are received, together with those of the flexor brevis digitorum, 
 into the sheaths upon the first and second phalanges ; and they have precisely the same 
 relations to the tendons of the last-mentioned muscle as the flexor profundus is observed 
 to have with regard to the flexor sublimis digitorum in the hand ; and hence the name 
 of jperforans given by Spigelius to the long flexor of the toes. The tendons are finally 
 inserted into the posterior extremities of the third phalanges. The tendinous parts of 
 this muscle are lubricated by synovial membranes where they pass through the different 
 sheaths. 
 
 Relations. — It is covered by the soleus, the posterior tibial vessels and nerves, and it 
 covers the tibia and the tibialis posticus. In the foot, it is covered below by the flexor 
 brevis digitorum and the adductor pollicis. 
 
 Action. — It flexes the third phalanges upon the second, the second upon the first, and 
 the first upon the corresponding metatarsal bones. When these movements have heen 
 accomplished, it extends the foot upon the leg. From the obliquity of its reflected por- 
 tion, it would turn the toes and the sole of tue foot slightly inward, if the accessory mus- 
 cle did not, as it were, rectify its action, as well as co-operate with it. In standing, it op- 
 poses flexion of the leg forward. 
 
 The Flexor Longus Pollicis. 
 
 The flexor longus pollicis is the most external and the largest muscle in the deep re- 
 gion of the leg : it is prismatic and quadrangular, vertical and fleshy in the leg {p, figs. 
 129, 130), tendinous and horizontal in the foot {p,figs. 131, 132). 
 
 Attachments. — It arises from the fibula, and is inserted into the last phalanx of the great 
 toe. Some of the fibres arise directly from the inferior two thirds, and from the internal 
 and external borders of the fibula ; others arise from the fascia covering the tibialis pos- 
 ticus (its origin from the fibula, and that from the fascia of the tibialis muscle, are sep- 
 arated from each other by the peroneal vessels) ; from a tendinous septum between it 
 and the peroneus longus and brevis ; and from a small portion of the lower part of the 
 interosseous ligament. From these numerous points of origin the fleshy fibres pass ob- 
 fiquely downward and backward, around a tendon which occupies the entire length of 
 the muscle, and may be seen at the lower part of the leg, through a thin layer of muscu- 
 lar fibres. These fibres terminate abruptly behind the ankle-joint, at the oblique groove 
 on the astragalus, in which the tendon is lodged ; it then turns into a groove on the os 
 cedcis, forming a continuation of the preceding (^fig. 133), and situated below that for the 
 tendon of the flexor longus digitorum, and dips into the sole of the foot. It is retained 
 in these two grooves, which run obliquely downward, inward, and forward, by a very 
 strong and continuous sheath (fig. 132). In the sole of the foot, the tendon is deeply 
 situated (p, fig. 131), passes forward, and crosses (p, fig. 132) at an acute angle above 
 the tendon of the flexor longus digitorum, to which it gives off" a considerable fibrous 
 
^relf MYOLOGY. 
 
 prolongation. It is then received in a groove formed between the flexor brevis digito- 
 rum and the oblique adductor of the great toe, passes below the anterior glenoid liga- 
 ment of the metatarso-phalangal articulation of that toe, between the two sesamoid 
 bones, and is received into the osteo-fibrous sheath of the first phalanx, to be inserted 
 into the posterior extremity of the second. 
 
 Relations. — It is covered by the soleus, being separated from it by a fascia, which in- 
 creases in thickness as it passes downward ; it is also covered by the tendo Achillis ; it 
 covers the fibula, the tibialis posticus, the peroneal artery, and the lower part of the in- 
 terosseous ligament. Externally, it is in relation with the peroneus longus and brevis ; 
 internally, with the flexor longus digitorum. 
 
 Action. — It flexes the second phalanx of the great toe upon the first, and this upon the 
 first metatarsal bone ; having produced these movements, it then extends the foot upon 
 he leg. From the obliquity of its fleshy belly, it has a tendency to turn the great toe 
 and the foot outward. In this respect it antagonizes the flexor longus digitorum and the 
 tibialis posticus. The very strong tendinous expansion which unites it to the long flexor, 
 of the toes consolidates the two muscles ; in fact, it is very uncommon to find either of 
 them acting independently. 
 
 MUSCLES OF THE FOOT. 
 
 The Extensor Brevis Digitorum. — Abductor Pollicis Pedis. — Flexor Brevis Pollicis Pedis. — 
 
 Adductor Pollicis Pedis. — Transversus Pollicis Pedis. — Abductor Minimi Digiti. — Flexor 
 
 Brevis Minimi Digiti. — Flexor Brevis Digitorum. — Flexor Accessorius. — Lumbricales. — 
 
 Interossei. 
 
 The muscles of the foot are divided into those of the dorsal and plantar aspects and 
 the interossei. The muscles of the plantar aspect may be again subdivided into three 
 regions, viz., those of the middle plantar region, those of the internal plantar region, and 
 those of the external plantar region. A single muscle occupies the dorsum of the foot, 
 viz., the extensor brevis digitorum. The muscles of the internal plantar region are four 
 in number, viz., the abductor, the flexor brevis, and the oblique and transverse adduc- 
 tors of the great toe. The last two muscles may be regarded as forming part of the 
 middle plantar region. 
 
 The muscles of the external plantar region are the abductor and the flexor brevis of 
 the little toe. 
 
 The muscles of the middle region are the flexor brevis digitorum, the flexor accesso- 
 rms, and the lumbricales. 
 
 The interosseous muscles are seven in number, and are divided into the dorsal and 
 plantar. 
 
 Dorsal Region. 
 
 The Extensor Brevis Digitorum. 
 
 DissectKm. — ^Remove the dorsal fascia of the foot, and the tendons of the muscles of 
 the anterior region of the leg. 
 
 The extensor brevis digitorum (q, fig. 128) is a thin, flat, quadrilateral muscle, situated 
 on the dorsum of the foot ; it is divided into four portions anteriorly, and is an accessor}' 
 of the extensor longus digitorum. It arises from the os calcis, and is inserted into the 
 first four toes. 
 
 It arises, by a rounded extremity, from a small excavation on the outside of the foot, 
 formed by the os calcis and the astragalus {the astragalo-calcanean fossa), and from the os 
 calcis, in front of that excavation. Its origin from these parts is both fleshy and tendi- 
 nous. The muscle then passes forward and inward, and soon divides into four fleshy 
 fascicuh, each representing a little penniform muscle, and terminating quickly in a small 
 tendon, the size of which is proportioned to the strength of the fasciculus. The inter- 
 nal tendon is the largest, because it is intended for the great toe ; it is situated below 
 the tendon of the extensor proprius pollicis, which it crosses at a very acute angle, and 
 is inserted into the dorsal surface of the proximal end of the last phalanx. The second, 
 third, and fourth tendons, intended for the second, third, and fourth toes, are subjacent 
 to the corresponding tendons of the extensor longus digitorum, which they cross at a 
 very acute angle. Having reached the metatarso-phalangal articulations, the tendons of 
 the short extensor are situated to the outside of those of the extensor longus, and are 
 blended with them, so as to complete the fibrous sheath on the dorsal surface of the first- 
 phalanx, and to terminate in a similar manner. 
 
 Relations. — It is covered by the dorsal fascia of the foot, by the tendons of the exten- 
 sor longus digitorum and extensor proprius pollicis ; it covers the second row of the tar- 
 sal bones, the metatarsus, and a small portion of the interosseous muscles and the pha- 
 langes. The arteria dorsalis pedis runs at first along the inner border of this muscle, 
 which overlaps the artery, where the latter perforates the first interosseous space, in 
 order to reach the sole of the foot. 
 
THE FLEXOR BREVIS POLLICIS PEDIS. 
 
 28T 
 
 Action. — It extends the first four toes ; it acts upon the first phalanx only of the great 
 toe. Its obliquity enables it to correct the contrary oblique movement communicated to 
 the toes by the contraction of the extensor longus digitorum ; so that the opposite ac- 
 tions of these two muscles are mutually destroyed, and the foot is extended directly. 
 Not uncommonly, the extensor brevis presents a fifth fasciculus, which is lost upon 
 some one of the metatarso-phalangal articulations. 
 
 Internal Plantar Region. 
 The muscles of the ball of the great toe may be divided, like those of the thumb, into 
 two orders, viz., those which pass from the tarsus to the inner side of the first phalanx, 
 and those which pass from the tarsus to the outer side of the same phalanx. Here, as 
 wifli the muscles of the thumb, the tendon of the flexor longus divides the flexor brevis 
 poUicis pedes of authors into two parts : one internal, forming the flexor brevis of the 
 great toe, properly so called ; the other external, which is found to be connected with 
 the oblique adductor of this toe. 
 
 Muscles inserted into the Inner Side of the First Phalanx of the Great Toe. 
 
 Dissection. — In order to expose the abductor brevis, it is sufficient to remove the in- 
 ternal plantar fascia ; the flexor brevis will be found under, i. e., deeper than the tendon 
 of the abductor brevis. 
 
 The muscles inserted into the inner side of the first phalanx of the great toe are the 
 abductor brevis and the flexor brevis. They are distinct at their origins, but are often 
 blended at their insertions ; so that Winslow united them together under the name of 
 le thenar du pied. 
 
 The Abductor PoUicis Pedis. 
 
 This muscle (le court adducteur,* Cruveilhier, r,fig. 131) is 
 the most superficial in the internal plantar region ; it arises 
 on the inside, from the internal posterior tuberosity of the os 
 calcis ; from the internal annular ligament under which the 
 posterior tibial vessels and nerves pass ; from the upper sur- 
 face of the internal plantar fascia ; and from the lower sur- 
 face of a tendinous expansion, which occupies the entire ex- 
 tent of the deep or superior surface of the muscle. From 
 these points the fleshy fibres proceed to the circumference of 
 a tendon (r, figs. 132, 133), which emerges from them infe- 
 riorly near the first cuneiform bone, but is often accompanied 
 by them superiorly as far as its insertion into the internal ses- 
 amoid bone, opposite the first phalanx of the great toe. 
 
 Relafio7is. — It is covered below by the internal plantar fas- 
 cia, and is divided from the muscles of the middle plantar re- 
 gion by a tendinous septum, which gives attachment to some 
 of its fleshy fibres. It is superficial to the flexor brevis poUi- 
 cis, the flexor accessorius, the tendons of the flexor longus 
 digitorum, and that of the flexor longus poUicis, the tarsal in- 
 sertions of the tibialis anticus and posticus, the plantar vessels 
 and nerves, and the internal articulations of the tarsus. 
 
 Action. — It is, properly speaking, a flexor of the great toe. 
 
 The Flexor Brevis PoUicis Pedis. 
 
 Adopting a similar plan in the definition of this muscle as in that of the short flexor 
 of the thumb, I shaU describe as the short flexor of the great toe that portion {s,fig. 133) 
 only of the flexor brevis of authors which extends from the second row of the tarsus to 
 the internal sesamoid bone of the metatarso-phalangal articulation of the great toe, and 
 sliall refer to the oblique adductor that portion (t) which is attached to the external ses- 
 imoid bone. This change appears to be warranted by the rule already laid down for the 
 distinction of muscles. Community of tlje fixed points of origin is not sufficient to es- 
 tablish the unity of two muscles, provided their movable insertions are distinct. A cel- 
 lular interval and the tendon of the flexor longus poUicis establish anteriorly the line of 
 demarcation between the flexor brevis and the adductor obliquus poUicis. 
 
 According to this view, the flexor brevis poUicis (s, figs. 131, 132, 133) arises from 
 the second row of the tarsus, particularly from the cuboid and the third cuneiform bones, 
 by some tendinous fibres which are formed by a continuation of the inferior ligaments of 
 the tarsus, and are common to this muscle and the internal portion (t) of the obliqne ad- 
 ductor of the great toe. The tendon of the tibialis posticus {n,fig. 133), or, rather, the 
 prolongation which this tendon gives off to the fourth metatarsal bone, also furnishes 
 Bome points of origin. The fleshy fibres proceeding from these different attachments 
 form a bundle that gradually increases in size, becomes separated from the oblique ad- 
 
 * See note, next page. 
 
MYOLOGY. 
 
 ductor, and terminates in a tendon which is inserted into the external sesamoid bone, 
 and also into the glenoid ligament of the metatarso-phalangal articulation. Not unfre- 
 quently the greater number of the fleshy fibres are attached to the tendon of the abduc- 
 tor brevis, and thus constitute the short head of a biceps muscle. 
 
 Relations. — The flexor brevis pollicis is in relation below with the internal plantar fas- 
 cia, and with the tendon of the abductor brevis pollicis, being moulded upon it, and usu- 
 ally separated from it by a tendinous sheath, except in those cases where the two mus- 
 cles are blended together. Observe that, at the point where the fleshy belly of the ab- 
 ductor terminates, the flexor brevis is in relation above with the tendon of the peroneus 
 longus {e,fig. 133) and the first metatarsal bone. ^ 
 
 Action. — The same as that of the preceding muscle, but it is much less powerful, ajid 
 less extensive. 
 
 Muscles inserted into the External Side of the First Phalanx of the Great Toe. 
 
 These are the oblique and transverse adductors.* 
 
 Dissection. — They are exposed by cutting across, and turning forward the flexor brevis 
 digitorum, the tendons of the flexor longus digitorum, and the flexor accessorius : par- 
 ticular care should be taken, when the dissection has extended as far as the heads of the 
 metatarsal bones, to avoid cutting the small transverse adductor. 
 
 The jJdductor Pollicis Pedis. 
 
 This (I'abducteur oblique, Cruveilhier, tt',fig. 133) is the largest of all the plantar mus- 
 cles ; it is prismatic and triangular, and occupies the great hollow formed by the last four 
 metatarsal bones, and is bounded by the first metatarsal bone on the inner side. It ex- 
 tends from the second row of the tarsus to the external sesamoid bone of the great toe. 
 It arises by two very distinct portions : the smaller {t,figs. 131, 132, 133), common to it 
 and to the flexor brevis, proceeds from the cuboid bone ; the other (f ) is mucli larger, 
 and arises Irom the slieath of the tendon of the peroneus longus (e), from the posterior 
 extremities of the tiiird, foiu-th, and fifth metatarsal bones, and from the transverse lig- 
 aments by which they are united. From these different origins the fleshy fibres pass 
 more or less obli<juely inward, and are inserted by a tendinous bundle into the external 
 sr-yaiiHiid bone of the metatarso-phalangal articulation of the great toe, and into the pos- 
 terior edge of the glenoid ligament of the same joint. 
 
 Relations. — Its inferior surface is in relation with the long and short flexors of the toes, 
 with tlie flexor accessorius, the lumbricales, and the plantar fascia ; its superior surface, 
 with the interosseous muscles and the external plantar artery ; audits inner surface, with 
 the first metatarsal bone, the tendon of the peroneus longus, and with the flexor brevis 
 pollicis. 
 
 Action. — It is a powerful adductor and flexor of the great toe. 
 
 The Transversus Pollicis Pedis. 
 
 This small transverse bundle (I'abducteur transverse, Cruveilhier, u, fig. 133) forms an 
 appendage of the preceding muscle, and is represented in the hand by the transverse 
 fibres of the adductor pollicis ; it extends from the fifth metatarsal bone to the external 
 sesamoid bone of the metatarso-phalangal articulation of the great toe. 
 
 This muscle, which is of variable size, arises externally from beneath the head of the 
 fifth metatarsal bone, by a tendinous and fleshy tongue, which is directed transversely 
 inward, is strengthened by other fibres arising from the anterior transverse ligament of 
 the metatarsus, and from the interosseous aponeurosis, and is inserted into the outer side 
 of the first phalanx of the great toe, where it is often blended with the attachment of the 
 oblique adductor. 
 
 Relations. — It is in relation below with the tendons of the long and short flexors of the 
 toes and with the lumbricalis, and above with the interosseous muscles. It is lodged ia 
 the anterior part of the deep concavity of the metatarsus, and is provided with a proper 
 sheath. 
 
 Actions. — It adducts the great toe, and draws the head of the metatarsal bones towards 
 each other. 
 
 * [The terms adductor and abductor arc applied by M. Cruveilhier to the muscles of the great toe, from their 
 respective actions upon it, in reference to the axis of the body ; the muscle attached to the inner side of that toe 
 being called its adductor, and those to the outer side its abductors. In the translation, however, the nomen- 
 clature of Albinus has been adopted, in which the terms adductor and abductor have reference to the axis of 
 the limb : first, because it is followed by the majority of authors ; and, secondly, because it is in accordance 
 with the principle observed by M. Cruveilhier himself, in describing not only all the muscles of the hand, but 
 some even of those of the foot, viz., the interossei, which are classed by him as abductors or adductors, accord 
 iug as they draw the several toes from or towards an imaginary axis passing through the second toe. By this 
 change much risk of perplexity will be avoided, and a uniform principle of nomenclature preserved as regards 
 all the muscles of the hand and foot. 
 
 In the description of each muscle of the great toe, the synonymes of Cruveilhier are given between brack 
 ets ; but in all instances, both here and hereafter, where these muscles have incidentally to be mentioned, the 
 names adopted from Albinus will be strictly adhered to. 
 
 It is vcarccly necessary to observe that the abductor of the little toe will still retain its name, j 
 
THE ABDUCTOR DIGITI MINIMI, ETC. 
 
 m 
 
 External Plantar Region. 
 The Abductor Digiti Minimi. 
 
 Dissection. — This is common to the abductor and the flexor brevis. The first is ex- 
 posed by simply removing the external plantar fascia, and the second by removing or re- 
 flecting down the first. 
 
 The abductor digiti minimi (,v,fig. 131) is of the same form, the saune structure, and al- 
 most the same size as the abductor pollicis, and extends from the os calcis to the first 
 phalanx of the little toe. It arises by tendinous and fleshy fibres from the external pos- 
 terior tuberosity of the os calcis, from the outer side of the internal posterior tuberosity, 
 and from an aponeurosis occupying the upper surface of the muscle. The fleshy fibres 
 having arisen in succession from these different points, proceed obliquely round a tendon, 
 from which they emerge, opposite the posterior extremity of the fifth metatarsal bone. 
 The fleshy belly of the muscle appears to end at this point, but it is continued by other 
 fibres, arising from the upper surface of the externd plantar fascia, and inserted either 
 into the common tendon, or separately, by the side of this tendon, into the outer part of 
 the first phalanx of the little toe. A small fleshy bundle is frequently detached from the 
 body of the muscle, and implanted into the posterior extremity of the fifth metatarsal 
 bone, together with a prolongation of the external plantar fascia, which serves as a ten- 
 don for it. 
 
 Action. — It is an abductor and flexor of the little toe. 
 
 The Flexor Brevis Digiti Minimi. ^s- 133. 
 
 This is a small fleshy fasciculus {x,figs. 131, 132, 133), situ- 
 ated along the external border of the fifth metatarsal bone, and 
 forming a continuation of the series of interosseous muscles, 
 with which it was for a long time confounded (interosseus, 
 Spigelius) : it extends from the second row of the tarsus, and 
 from the fifth metatarsal bone, to the first phalanx of the little 
 toe. It arises from the ligamentous layer covering the plantai 
 surface of the metatarsal row of the tarsal bones, and from the 
 posterior extremity of the fifth metatarsal bone ; it is inserted 
 into the outer side of the first phalanx of the little toe, or, more 
 correctly, into the posterior edge of the glenoid ligament of the 
 metatarso-phalangal articulation of that toe. Some of the 
 fleshy fibres will be found attached to the entire length of the 
 externjd border of the fifth metatarsal bone ; and these some- 
 times form a small and very distinct muscle, representing the 
 opponens digiti minimi of the hand. 
 
 Relations. — It is covered below by the plantar fascia, which 
 is here very thin, and also by the tendon of the abductor digiti 
 minimi ; it is in relation above with the fifth metatarsal bone 
 and the first plantar interosseous muscle. 
 
 Action. — The same as that of the preceding muscle with re- 
 gard to flexion, but its action is less powerful and less exten- 
 sive. 
 
 Middle Plantar Region. 
 The Flexor Brevis Digitorum. 
 
 Dissection. — Remove the plantar fascia, which is intimately united to this muscle pos- 
 teriorly. 
 
 The flexor brevis digitorum {y,fig. 131) is a short, thick muscle, narrow behind, and' 
 divided into four tendons in front. It arises from the inside of the external tuberosity 
 of the OS calcis, from the upper surface of the middle plantar fascia, from a special ten- 
 dinous expansion occupying the lower surface of the muscle, and appearing to be a de- 
 pendance of the plantar fascia ; and, lastly, from an aponeurotic septum, situated between 
 Ti. and the muscles of the external plantar region. It forms a fleshy belly, which is nar- 
 row and thick behind, passes directly forward, increases in breadth, and soon divides 
 into four, sometimes only into three fasciculi, constituting as many small and perfectly 
 distinct penniform muscles, the long and delicate tendons of which emerge from the 
 fleshy fibres before reaching the metatarso-phalangal articulations, become flattened, and 
 are then situated below and in the same sheath with the tendons of the flexor longus. 
 Opposite the first phalanx each tendon of the short flexor bifurcates, to allow the passage 
 of the corresponding tendon of the flexor longus, is formed into a groove, becomes re- 
 united above the latter tendon, and once more bifurcates, in order to be inserted along 
 the borders of the second phalanx (hence it was named perforatus by Spigelius, and le 
 perfore du pied by Winslow). The short flexor of the toes is, therefore, analogous to the 
 superficial flexor of the fingers. 
 
 Relations. — It is covered below by the plantar fascia and the skin ; it is in relation 
 
 Oo 
 
;20O MYOLOGY. 
 
 above with the plantar vessels and nprves, with the tendon of the flexor longus digitorum, 
 and with the flexor accessorius and the lumbricales, from which it is separated by a tendi- 
 nous lamina. On its outer and inner side it is completely isolated from all the adjacent 
 muscles by prolongations of the plantar fascia. 
 
 Action. — It flexes the second phalanges of the last four toes upon the first phalanges, 
 and these upon the corresponding metatarsal bones. 
 
 The Flexor Accessorius. 
 
 This is a flat, quadrilateral muscle, forming a considerable fleshy mass (massa carnea, 
 Jacobi Sylvii, z,fig. 132) ; it arises, by a bifurcated extremity, from the lower part of the 
 groove of the os calcis, and a small part of the calcaneo-scaphoid ligament by fleshy 
 fibres, and by means of a tendon from the lower surface of the same bone, this tendon 
 sometimes extending as far as the external posterior tuberosity of the os calcis. From 
 these points the fleshy fibres pass directly forward, and terminate in the following man- 
 ner : the lower fibres become inserted into the outer margin, and a small portion of the 
 inferior surface of the tendon of the flexor longus digitorum ; while the upper are inserted 
 into several small fibrous bundles, which unite together, receive a considerable expan- 
 sion from the tendon of the flexor longus poUicis, and are ultimately blended with, and 
 increase the size of the divided tendon of the flexor longus digitorum. 
 
 Relations. — This muscle is in relation below with the flexor longus digitorum and the 
 plantar vessels and nerves, and abme with the os calcis and the inferior calcaneo-cuboid 
 ligaments. 
 
 Action. — It is a muscle of re-enforcement, and assists in flexing the toes ; from its obli- 
 quity, it rectifies the oblique action of the flexor longus digitorum in the opposite direction. 
 
 The Lumbricales. 
 
 The lumbricales Q, I, figs. 131, 132), which form a second class of accessory muscles 
 belonging to the flexor longus digitorum, exactly resemble the lumbricales of the fingers ; 
 they consist of four small fleshy tongues, decreasing in size from within outward, the two 
 outer of which are not unfrequently atrophied ; they extend from the angles formed by 
 the division of the tendons of the flexor longus to the inner or tibial borders of the first 
 phalanges of the last four toes, and to the corresponding margins of the extensor tendons. 
 They are distinguished by the numerical names of first, second, third, and fourth. The 
 first is situated parallel with the flexor tendon of the second toe. 
 
 Relations. — They are covered below by the flexor brevis digitorum ; they emerge from 
 beneath the plantar fascia, in the interval between the sheaths furnished by it to the 
 flexor tendons, gain the inner side of the corresponding metatarso-phalangal articulation, 
 and terminate upon the first phalanx and inner margin of the tendons of the extensor 
 longus digitorum. They have the same action as the lumbricales of the hand. 
 
 Interosseous Region. 
 The Interossei. 
 The interosseous muscles of the foot correspond exactly with those of the hand, and 
 require the same consideration. 
 
 They arise from the lateral surfaces of the interosseous spaces in which they are 
 placed ; and are inserted into the sides of the first phalanges and the corresponding mar- 
 j^. 133. gins of the tendons of the extensor muscles. They are seven in 
 
 number, viz., four dorsal (three of which are seen at d d d, fig. 
 133), and three plantar {p j) p); to the latter, however, the ob- 
 lique adductor of the great toe may be added, for it is nothing 
 more than a very large plantar interosseous muscle. 
 
 As in the hand, the dorsal interossei are abductors, their origins 
 being situated externally to the axis of the foot ; the plantar inter- 
 ossei, again, are adductors ; but the axis of the foot must be suppo- 
 sed to extend through the second, and not through the middle toe. 
 As we observed in the hand, the dorsal interossei project into the 
 plantar region, by the side of the plantar muscles ; and so narrow 
 are the interosseous spaces in the foot, that these dorsal muscles 
 are much more completely situated in tlie plantar than those of the 
 hand in the palmar region. The palmar interossei correspond- 
 ing to the fourth and fifth toes, arise not only from the lower two 
 thirds of the internal or tibial side of the corresponding metatar- 
 7" sal bone, but also from the lower surface of the posterior extrem- 
 ity of the same bone. It follows, therefore, that the interosseous 
 muscles, viewed from below, appear one continuous muscle, in 
 which it would be difficult to separate the muscles of each space, 
 if the interosseous plantar fascia did not give off prolongations 
 between them ; elsewhere, a cellular line defines the limit be- 
 tween each plantar and dorsal muscle. 
 
PHYSIOLOGICAL ARRANGEMENT OF THE MUSCLES. 
 
 Again, as in the hand, the dorsal interossei arise from two corresponding metatarsal 
 bi)nes at once, but more especially from the lateral surface of that metatarsal bone which 
 is directed/rota the axis of the foot : as in the hand, also, their posterior extremities are 
 perforated by the posterior perforating arteries, the first being perforated by the arteria 
 dorsalis pedis. The plantar interossei arise from only one of the metatarsal bofnes, and 
 from the lateral surface that is directed towards the imaginary axis of the foot ; moreover, 
 they do not arise from the entire thickness of the bone, but only from its inferior two 
 thirds, since the upper third is covered by the dorsal muscle. 
 
 The following are the general relations of the interossei : they are separated above 
 from the tendons of the extensors by a layer of fibrous tissue, and by the dorsal inter- 
 osseous fascia ; and below from the proper muscles of the foot, by the deep plantar in- 
 terosseous fascia, which is much stronger than the corresponding structure in the hand, 
 and gives off septa between the different pairs of interosseous muscles. 
 
 PHYSIOLOGICAL ARRANGEMENT OF THE MUSCLES. 
 
 However important it may be to become acquainted with the order of super-imposi- 
 tion, or the topographical arrangement of the muscles, it is no less necessary to study 
 the retrospective uses, in other words, the physiological arrangement of these organs* 
 In order to obtain, as much as possible, the advantages of each of these two methods, 
 having already described each muscle in its topographical order, I shall now give a table 
 of the muscles, arranged according to their physiological relations. It is important to 
 observe that the terms muscles of the arm, of the thigh, <fc., have not the same accepta- 
 tion in the two arrangements. Thus, by the term muscles of the £irm, in the topographi 
 ical order, we mean the muscles which occupy the region of the arm, as the deltoid, bi- 
 ceps, &c. ; but, in the physiological arrangement, the same term is applied to the mus- 
 cles which move the arm, viz., the pectoralis major, latissimus dorsi, &c. 
 
 Muscles of the Vertebro-cranial Column. 
 
 These are divided into the extensors, the flexors, and the lateral muscles or lateral 
 flexors, which incline the vertebral column to one side or the other. There are no rota- 
 tors, for rotation is performed by the extensor muscles. 
 
 Extensors. — These occupy the posterior region of the vertebral column. They con- 
 sist, on each side, of, 1. The posterior spinal, or long muscles of the back, divided into 
 the sacro-lumbalis, longissimus dorsi, and transverso-spinalis ; 2. Of the transversalis 
 colli and the trachelo-mastoideus, which may be regarded as accessory fasciculi to the 
 longissimus dorsi ; 3. Of the splenius, or representative of the longissimus dorsi of the 
 neck and head ; 4. Of the complexus, or transverso-spinalis of the head ; 5. Of the m- 
 ter-spinales, in which the two recti postici of the head may be included ; 6. Of the ob- 
 liquus major, or spino-transversalis of the atlas ; 7. Of the obliquus minor, or transverse 
 spinalis of the head. 
 
 Flexors. — These are situated on the anterior region of the vertebro-cranial column. 
 The most important of these muscles are carried forward, and attached to the sternum, 
 and to those long transverse processes called the ribs. They are on each side, 1. The 
 rectus abdominis ; 2. The stemo-cleido-mastoideus. The other muscles that co-operate 
 in flexion occupy the deep anterior cervical region, viz., 1. The rectus capitis auticus 
 major ; 2. The rectus capitis anticus minor ; 3. The longus colli. 
 
 Lateral Muscles. — These are, 1. The inter-transversales oCthe neck and loins, among 
 which I include the rectus capitis lateralis ; 2. The scaleni anticus et posticus ; 3. The 
 quadratus lumborum. 
 
 Muscles of the Ribs, or of the Thoracico-abdominal Parietes. 
 These are, 1. The inter-costales, externi and intemi, which are both elevators and 
 depressors; 2. The small accessory muscles, viz., the infra-costales of Verheyen and 
 the supra-costales, or levatores costarum, the latter being always elevators ; 3. The ser- 
 rati postici superiores, which are elevators ; 4. The serrati postici inferiores, depressors ; 
 5. The triangularis stemi, or small anterior serratus, also a depressor ; 6. The diaphragm, 
 a muscular septum, the contraction of which increases the vertical diameter of the tho- 
 riix, and draws the ribs inward. Tlie muscles of the abdominal parietes are so intimate- 
 ly connected in action with those of the thorax, that the description of the former nat- 
 urally follows that of the latter. The abdominal muscles, then, may be regarded as mus- 
 cles of expiration, and are all depressors of the ribs. There are, 1. The obliqims exter- 
 
 * Custom, rather thtn conviction, has induced me to prefer the topographical to the physiological arrange- 
 ment. The only objection which can be nrped against the latter is, that it does not permit all the muscles 
 to be dissected upon the same subject ; but this objection applies only to a few regions ; and as these regions 
 exist in pairs, the superficial muscles on one side might surely be sacrificed. Moreover, there is no reason 
 why the examination of the deep-seated muscles should not be postponed until the superficial ones have been 
 studied. I therefore direct students to dissect these parts sometimes according- to their topographical, and 
 at others after their physiological order 
 
fSffSt MYOLOGY. 
 
 nus, which is nothing more than a large external intercostal muscle, extending between 
 the ribs and the pelvis ; 2. The obliquus internus, which may be regarded as a large 
 internal intercostal muscle, of which the cremaster is a dependance ; 3. The trai sversa- 
 lis, which we may consider as forming with the diaphragm a single muscle, intermpted 
 by its costal attachments. 
 
 Muscles which move the Lower Jaw. 
 As the bones of the upper jaw are immovably articulated together and to the cranium, 
 they have no proper muscles. The muscles of the face do not belong to them, but are 
 true cutaneous muscles, attached to the different bones only for the purpose of having 
 fixed origins. The lower jaw, on the contrary, is provided with two principal orders of 
 muscles, elevators and depressors, to which are added diductors (from diduco, to draw aside). 
 The elevators and diductors preponderate ; the only office of the depressors is to bring 
 down the jaw into a position from which it may then be raised. 
 
 1. Elevators. — These are the masseters, the temporales, and the pterygoidei interni. 
 
 2. Diductors, viz., the pterygoidei extemi. 
 
 3. Depressors, consisting of the muscles of the supra- and infra-hyoid regions, and 
 more particularly of the two digastrici. 
 
 Muscles which move the Os Hyoides. 
 
 These are divined into elevators and depressors. 
 
 All the elevators belong to the supra-hyoid region, and are, 1. The stylo-hyoidei ; 2. 
 The mylo-hyoidei ; 3. The genio-hyoidei. 
 
 The depressors consist of the muscles of the infra-hyoid region, viz., 1. The sterno- 
 hyoidei ; 2. The stemo-thyroidei ; 3. The thyro-hyoidei ; 4. The omo-hyoidei. 
 
 Muscles which move the Pelvis. 
 There are no muscles proper to the pelvis. The ischio-coccygeus is the only intrinsic 
 muscle. The extrinsic muscles attached to the pelvis do not belong to its cavity, but 
 merely take their fixed points from its parietes. It is only under particular circumstan- 
 ces that the pelvis changes its usual office, and becomes the movable point ; for exam- 
 ple, in the horizontal position, in the action of climbing, and in the reversed attitude of 
 a tumbler, the pelvis is moved upon the vertebral column on the one hand, and upon the 
 femur on the other. 
 
 Muscles which move the Shoulder. 
 Tlie muscles of each shoulder are divided into elevators and depressors, both of which 
 are also rotators. The elevators are, 1. The trapezius ; 2. The rhomboideus ; 3. The 
 levator anguli scapulae. The depressors are, 1. The pectoralis minor ; 2. The subclavius ; 
 3. The serratus magnus. The elevators and depressors of the entire shoulder must be 
 carefully distinguished from those which raise' or depress its apex. 
 
 Muscles which move the Thigh upon the Pelvis. 
 
 Tliese muscles are divided into extensors, flexors, adductors, abductors, and rotators 
 
 The extensors and abductors are the same, viz., the three glutaei. 
 
 The conjoined psoas magnus, iliacus, and psoas parvus constitute the only_^xor. 
 
 Adduction is performed by four muscles, viz., the pectineus and the three adductors. 
 
 Rotation outward is performed by six muscles, viz., the pyriformis, the two gemelli, the 
 obturator internus, the quaflratus femoris, and the obturator externus. 
 
 Rotation inward is performed by the tensor vaginae femoris, and especially by the an 
 terior fibres of the glutaei, medius et minimus. 
 
 Muscles which move the .Mrm upon the Shoulder. 
 
 These muscles are divided into abductors, which are at the same iivae flexors, and into 
 adductors and rotators. There are no proper muscles for the movement forward or flexion, 
 nor for the movement backward or extension, both of which motions are effected by the 
 adductors and abductors. 
 
 The abductors are, 1. The deltoideus ; 2. The coraco-brachialis ; 3. The supra-spi- 
 natus. 
 
 The adductors are, 1. The pectoralis major ; 2. The latissimus dorsi ; 3. The teres 
 major. 
 
 The rotators are, 1. The external, viz., the infra-spinatus and the teres minor ; 2. The 
 internal, viz., the sub-scapularis. 
 
 Muscles which move the Leg upon the Thigh. 
 
 These are divided into flexors and extensors. The flexors are, 1. The biceps femoris ; 
 2. The semi-tendinosus ; 3. The semi-membranosus ; 4. The popliteus ; 5. The sarto- 
 rius ; 6. The gracihs. 
 
 Extension is performed by one muscle only, viz., the triceps femoralis, the long head 
 
PHYSIOLOGICAL ARRANGEMENT OF THE MUSCLES. 
 
 of which is fonned by the rectus femoris, and the other two heads by the triceps cruris 
 of authors, viz., the vastus externus and vastus internus, including the crureus. 
 
 I should remark, that all these muscles which arise from the pelvis perform the double 
 function of moving the leg upon the thigh, and the thigh upon the pelvis. 
 
 Muscles which move the Forearm upon the Arm. 
 These are divided into flexors and extensors. The flexors are the biceps and the 
 brachialis anticus. The extensors are, 1. The triceps (of which the long head resembles 
 the rectus femoris) ; 2. The anconeus. 
 
 Muscles which move the Radius upon the Ulna. 
 These are rotators inward, or pronators, viz., 1. The pronator teres ; 2. The pronator 
 quadratus; and rotators outward, or supinators, viz., 1. The supinator longus ; 2. The 
 supinator brevis. The pronators occupy the anterior region, the supinators the poste- 
 rior region of the forearm. 
 
 Muscles which move the Hand upon the Forearm. 
 
 These are divided into flexors and extensors. The flexors are, 1. The flexor carpi 
 radialis ; 2. The palmaris longus ; 3. The flexor carpi ulnaris. The extensors are, 1. 
 The extensores carpi radiales, longior et brevior ; 2. The extensor carpi ulnaris. 
 
 Adduction and abduction are also performed by these muscles. 
 
 Muscles which move the Fingers. 
 
 These are divided into extensors, flexors, adductors, and abductors. The extensors 
 are, 1. The extensor communis digitorum; 2. The extensor digiti minimi; 3. The ab- 
 ductor longus pollicis ; 4 and 5. The extensor brevis and extensor longus pollicis ; 6. 
 The extensor proprius indicis. 
 
 The flexors are, 1. The flexor sublimis digitorum ; 2. The flexor profundus digitorum, 
 and its accessories, the lumbricales ; 3. The flexor longus pollicis. 
 
 The extensors and the flexors of the fingers are all situated in the forearm ; the ad- 
 ductors and abductors belong to the hand : they consist of the interossei, which are seven 
 in number, four dorsal, constituting the abductors, and three palmar, which are adductors. 
 
 Other muscles are also superadded to the thumb and the little finger; The muscles 
 superadded to the thumb are, 1. Those which constitute the thenar eminence (ball of 
 the thumb), viz., the abductor brevis, the opponens, and the flexor brevis ; 2. The ad- 
 ductor pollicis, which is nothing more than a palmar interosseous muscle. The mus- 
 cles su|)eradded to the little finger constitute the hypothenar eminence (ball of the little 
 finger), and form, as it were, a repetition of those of the thenar eminence, viz., the ab- 
 ductor brevis, the flexor brevis, and opponens. But although three only are thus de- 
 scribed, it is because the palmar interosseous muscle of the little finger, which repre- 
 sents the adductor poUicia, presents no peculiarities, and is, therefore, classed with the 
 other palmar interossei. 
 
 Muscles which move the Foot upon the Leg. 
 
 These are divided into flexors and extensors : the same muscles also produce, at the 
 articulation of the two rows of the tarsal bones, movements of rotation, which corre- 
 spond to adduction and abduction. 
 
 The extensors are, 1. The gastrocnemius and soleus, or the triceps suralis, with which 
 we describe a small rudimentary muscle, the plantaris. 2. The tibialis posticus. 3. The 
 peroneus longus et brevis. 
 
 There is only one flexor, viz., the tibialis anticus. The peroneus tertius, when it ex- 
 ists, is merely a dependance of the extensor longus digitorum. 
 
 There are no muscles in the leg analogous to the pronators and supinators of the fore- 
 arm. 
 
 Muscles which move the Toes. 
 
 These are divided into extensors and flexors. 
 
 The extensors are, 1. The conjoined extensor longus digitorum and peroneus tertius. 
 2. The extensor proprius pollicis. 3. The extensor brevis digitorum. The flexors are, 1. 
 The flexor longus digitorum, and its accessories, the lumbricales. 2. The flexor brevis 
 digitorum ; the flexor longus pollicis. 
 
 Contrary to what we have seen with regard to the fingers, many of the flexors and ex- 
 tensors of the toes form part of the intrinsic muscles of the foot. As in the hand, the ad- 
 ductors and abductors of the toes occupy the thenar, hypothenar, and interosseous regions. 
 
 The interosseous muscles are adductors and abductors of the toes ; they are seven in 
 number, four dorsal, being the abductors, and three plantar, acting as adductors. 
 
 The superadded muscles of the great toe are, 1. The muscles of the thenar eminence, 
 viz., the abductor brevis and the flexor brevis. 2. The adductor obliquus, and the ad- 
 ductor transversus. The muscles superadded to the little toe are the muscles of the hy- 
 pothenar eminence, viz., the abductor and the flexor brevis. 
 
APONEUROLOGY. 
 
 Cutaneous Muscles, 
 
 These muscles, which are inserted into the skin by one of their ecxtremities at least, 
 are in the human subject concentrated round the openings in the face, with a single ex- 
 ception, viz., the palmaris brevis. 
 
 The cutaneous muscles of the ear belong to the orifice of the external auditory meatus, 
 and are £ill rudimentary in man. They form the three auricular muscles. 
 
 The muscles of the eyelids, on either side of the face, are divided into constrictors and 
 dilators. There is only one constrictor, the orbicularis palpebrarum, of which the comi- 
 gator supercihi may be considered an accessory. 
 
 There are two dilators, viz., the levator palpebrae superioris and the occipito-frontalis. 
 
 The cutaneous muscles of the nose consist of four or five pairs, i. e., on each side of the 
 face, of the pyramidalis nasi, the levator labii superioris alaeque nasi, the transversalis 
 nasi, the depressor alae nasi or myrtiformis, and the naso-labialis of Albinus. 
 
 The cutaneous muscles of the lips are, 1. A constrictor, viz., the orbicularis oris. 2. 
 Nine pairs of dilators, consisting, on each side, of the levator labii superioris alaeque nasi 
 already mentioned, the levator labii superioris, the zygomaticus major, the caninus, the 
 buccinator, the triangularis oris, the quadratus menti, the levator labii inferioris, the pla 
 tysma myoides ; and often of two accessory muscles, viz., the risorius of Santorini, and 
 the zygomaticus minor. 
 
 APONEUROLOGY. 
 
 General Observations on the Aponeuroses. — Structure. — Uses. 
 
 The aponeuroses are fibrous membranes, arranged in the form of inextensible textures, 
 which constitute sheaths for the muscles, and, at the same time, afford them broad sur- 
 faces for attachment. The aponeuroses are generally known, at the present day, by the 
 name oi fascia {fascia, a band), an expression which was at first appUed exclusively to 
 the strong, broad aponeurotic band, forming the termination of the tensor vaginae femoris, 
 and part of the fascia lata of the thigh. 
 
 The aponeuroses constitute important adjuncts to the system of locomotion. They 
 were for a long time neglected, or, rather, studied independently of each other, and then 
 only partially, until Bichat gave a general view of them, in his division of the fibrous sys- 
 tem, including the membranous forms of that tissue, of which the aponeuroses form the 
 greatest part. 
 
 As the aponeuroses have now become the object of numerous researches, and even 
 the subject of some special treatises,* I have considered that it would be useful to offer 
 a description of all the aponeuroses of the human body under the head of Aponeurology. 
 This grouping together of analogous parts will have the double advantage of simplifying 
 the description of the particular aponeuroses, by making them elucidate each other, and 
 of bringing into prominent notice a system of organs, the study of which is generally neg- 
 lected in anatomical lectures. 
 
 General Observations. — The aponeuroses are divided by Bichat into two distinct class- 
 es, one serving for the insertion of muscles, viz., the aponeuroses of insertion ; the other 
 for investing or containing the muscles, called the investing or confining aponeuroses. 
 Many aponeuroses serve both these purposes at the same time ; but, in general, one or 
 the other function predominates in each. 
 
 The aponeuroses of insertion^ are subdivided into those formed by the expanded con- 
 tinuations of tendons, and those which do not originate in tendons. The aponeuroses 
 of the gastrocnemius and soleus belong to the first class ; those of the broad muscles of 
 the abdomen are examples of the second : in the latter case, the aponeuroses serve both 
 for the insertion and investment of the muscles. Sometimes the aponeurosis occupies 
 the middle of a muscle ; as, for example, the cordiform tendon of the diaphragm, and the 
 aponeuroses of the occipito-frontalis. The use of the aponeuroses of insertion evident- 
 ly has reference to the great number of muscular fibres, all of which could not have been 
 attached to the limited superficies of the skeleton. 
 
 The investing aponeuroses occasionally form a sheath for the entire limb, sometimes 
 for only a single muscle, and at others for several muscles. The first set are called gen- 
 eral, the other two partial aponeuroses. 
 
 The aponeuroses are found not only in the extremities where they perform such im- 
 portant offices, but also in the trunk. As a general rule, wherever there exists a muscle 
 fulfilling any special purpose, and susceptible of displacement during its contraction, we 
 find an aponeurosis, or, rather, an aponeurotic sheath ; and the thickness of this sheath 
 is proportioned to the length and strength of the muscle, and especially to its tendency 
 to displacement. 
 
 * Godman, of Philadelphia, published in 1824 a special work upon the fascise ; and Paillard a treatise upOB 
 the aponeuroses of the human body in 1827. t See note, p. 296. 
 
GENERAL REMARKS UPON THE APONEUROSES. 295 
 
 Each aponeurosis presents for our consideration an external and an iTitemal surface, a 
 superior border or circumference, sometimes termed its origin, and an inferior border or 
 circumference, sometimes called its termination. 
 
 1. The external surface of the general investing aponeuroses is in contact with the sub- 
 cutaneous cellular tissue, from which it is separated by the superficial veins, lymphatics, 
 and nerves. The skin is therefore movable upon these aponeuroses, excepting in some 
 situations, as in the palms of the hands and soles of the feet, where it is intimately uni- 
 ted to the fasciae by prolongations from the inner surface of the cutis. What, indeed, 
 would be the consequences with regard to the sense of touch, or in the attitude of stand- 
 ing, if the skin over those regions were as movable as it is upon the thigh 1 The same 
 adhesion is also observed between the hairy sc£dp and the subjacent aponeurosis. 
 
 The mobility of the skin upon the aponeuroses depends upon the following contrivance : 
 From the inner surface of the skin are given off a great number of prolongations, which, 
 having intercepted the areolae containing the adipose tissue, unite together, and expand 
 into a membrane, which glides over the aponeuroses and the superficial vessels and 
 nerves : the sub-cutaneous membrane thus formed bears, the name of the fascia superfici- 
 alis : it is only distinctly seen in regions that are traversed by superficial vessels and 
 nerves, as in the lower part of the abdomen, and on the extremities. 
 
 2. The deep surface of a general investing aponeurosis presents fibrous prolongations 
 passing between the different layers of muscles, and even between the muscles of which 
 these layers are composed. Moreover, this surface and its several prolongations some- 
 times afford attachments to the superficial muscles, and sometimes it glides over the mus- 
 cles and their tendons by means of a very loose filamentous cellular tissue — an arrange- 
 ment that prevails throughout the greater part of the extent of this surface. Lastly, 
 amid aU these sheaths for the muscles, there exists a proper sheath for the principal 
 vessels of the extremities. 
 
 These aponeurotic sheaths are not so exactly moulded upon the muscles as not to ad- 
 mit of the accumulation of a certain quantity of fat in their interior ; nevertheless, their 
 capacity is so far proportioned to the size of the muscles, that the latter, during their 
 contraction, experience a degree of pressure from them which is highly favourable to 
 their action, at the same time that it prevents all displacement. 
 
 In emaciated individuals, these sheaths are no longer filled by their respective mus- 
 cles ; and, without doubt, the want of a due compression upon the muscles has some in- 
 fluence in producing the weakness experienced by convalescents, or by those wasted by 
 some chronic disease. 
 
 3. The borders or circumferences of aponeuroses, incorrectly named their origin and ter- 
 mination, are either continuous with the aponeuroses of the adjacent regions, or are at- 
 tached to the processes on the articular extremities of the bones, or result, in part, from 
 the expansion of tendons. 
 
 The aponeuroses are perforated by vessels and nerves, which, in such cases, are gui- 
 ded and protected by arches, rings, or canals of fibrous tissue : of this nature are the 
 sheaths of the femoral artery and vein, and of the brachial artery and veins, the femoral 
 arch, the canal and arch of the adductor muscles of the thigh, the arch of the obturator 
 foramen, and the aortic arch of the diaphragm ; these canals and arches tend to prevent 
 any injury to the vessels and nerves by which they are traversed during the contraction 
 of the muscles. We must not suppose, however, that the vessels are exempt from all 
 pressure ; for experience has proved that arteries are particularly liable to become affect- 
 ed with aneurism in the neighbourhood of such arches ; as, for example, the popliteal and 
 femoral arteries and the aorta. The muscular fibres, in fact, are not attached to these 
 arches in such a manner as to dilate them in all directions during their contraction, but 
 rather in such a way as to elongate them in one direction and contract them in another. 
 
 All the aponeuroses, whether of insertion or investment, have their tensor muscle. 
 With regard to the aponeuroses of insertion, this requires no proof; for the action of the 
 muscle or muscles to which they afford attachment must necessarily render them tense. 
 It is no less true, however, of the investing aponeuroses, some of which have even a sep- 
 arate muscle for this purpose. Thus, the occipital and frontal muscles are tensors of the 
 occipito-frontal aponeurosis. The fascia lata is rendered tense by the tensor vaginae fe- 
 moris, the palmar fascia by the palmaris longus, &c. 
 
 The aponeuroses of both kinds are inextensible, resisting, and insensible membranes, 
 their thickness and strength being exactly proportioned to the resisting power and strength 
 of the muscles which are invested by them, or to which they afford the means of inser 
 tion. Thus, the fascia of the thigh is very much stronger than that of the arm : the thick- 
 ness of the aponeuroses increases from the upper to the lower part of the limbs ; and, 
 again, the powerful vastus externus is provided with a much stronger sheath than the 
 muscles of the posterior, or of the internal region of the thigh. We may, then, consider 
 it as a general law, without exception, that the aponeurotic system invariably presents a 
 corresponding degree of development to that of the muscular system. "VVe should, there 
 fore, study the aponeuroses, as well as the muscles, upon robust subjects ; their pearly 
 aspect is destroyed in individuals wasted by chronic diseases. The aponeurotic and 
 
296 APONEUROLOGY. 
 
 muscular systems are both most fully developed in carnivora, in which class of animals 
 the pearly appearance is peculiarly well marked, and the cellular tissue is often replaced 
 by a fibrous texture ; a transformation which proves the analogy of the cellular and fibrous 
 tissues in organization, vitality, and function.* 
 
 The thinner fasciae are composed of a single layer of parallel fibres, which have be- 
 tween them intervals of different sizes : stronger aponeuroses are composed of several 
 planes, the fibres of which intersect each other at various angles. The vessels and 
 nerves of the aponeuroses are little known ; but I believe that I have traced nerves into 
 them. I have certainly done so with regard to the dura mater.* 
 
 I shall include among the aponeuroses the fibrous sheaths of tendons,* which are some- 
 times presented under the form of imperfect rings, or canals of different lengths, which 
 retain the tendons in contact with the bones. They serve to confine the tendons, to 
 keep them applied against the bones, and to favour their reflection. 
 
 The periosteum* must also be annexed to the aponeurotic system ; it is a tnie aponeu- 
 rosis, covering every part of the bones, and constituting a fibrous sheath for them. We 
 may consider the periosteum as the central point of the aponeurotic system, proceeding 
 from which, we find either tendons expanding upon the surface or in the substance of 
 muscles, and constituting the aponeuroses of insertion ; or else those fibrous cones or pyr- 
 amids, from the interior of which the fleshy fibres take their origin. From the perioste- 
 um, or, rather, from the ridges or clefts by which the surfaces of bones are marked, both 
 the partial and general investing aponeuroses arise. In this way the muscles of the ex- 
 tremities are situated between two fibrous layers ; the deep layer consisting of the peri- 
 osteum, the superficial layer of the general investing fascia : numerous septa pass from 
 one to the other, and divide the limb into a number of compartments, intended to isolate, 
 confine, and protect the different muscles. 
 
 Use of the Aponeuroses. — Forming, as they do, an important division of the fibrous tex- 
 tures, they partake of the physical, chemical, anatomical, physiological, and pathological 
 properties of that tissue. 
 
 1. From their great strength, they are enabled to resist the powerful traction and dis- 
 tension exercised upon them by the muscular fibres. Their division or destruction is 
 accompanied by displacement of the parts which they are intended to bind down. Be- 
 tween the different layers of the regions of the body they establish very precise limits, a 
 knowledge of which is of the greatest importance, in enabling us accurately to accoxmt 
 for many morbid phenomena, and in guiding us in the performance of surgical operations. 
 
 2. They are inextensible ; hence the resistance which they oppose to the development 
 of subjacent parts, and the tension produced by inflammation of organs situated beneath 
 them. They yield to gradual distension, but then become thinner and weaker, and can 
 only imperfectly fulfil their proper offices. 
 
 3. They are totally inelastic, and, therefore, when distended beyond a certain point, 
 never return to their original dimensions. Of this we have an example in the condition 
 of the abdominal parietes after utero-gestation, or ascites. 
 
 4. The low degree of vitality they possess explains why they are so slightly involved 
 in inflammation or other morbid conditions of the adjacent structures, and also the fact 
 of their establishing limits beyond which these diseases seldom pass. They are insen- 
 sible to all ordinary stimuli, but become painful when they are violently overstretched 
 The plantar fascia, under such circumstances, becomes extremely sensitive. 
 
 Having made these general remarks, we shaU now describe, in succession, the prin- 
 cipal aponeuroses of the human body.f 
 
 • See note, infra. 
 
 t Note on Aponeurology. — [The analogy existing' between the cellular and aponeurotic investments of various 
 organs renders it advantageous to consider in this place the general a.n-Atomy of the cellular and fibrous tissues. 
 
 The ultimate elements of both these kinds of tissue are precisely similar, though somewhat differently ar- 
 ranged in each ; they consist of delicate transparent filaments, varying in diameter from ^^j-^ ^^^ th to yj^Tj-g^th 
 of an inch, and having a peculiar sinuous or undulating direction ; they are insoluble in cold water, but by 
 long-continued boiling are almost entirely converted into gelatine. 
 
 In cellular tissue these undulating filaments are arranged side by side, either into larger compound and flei- 
 uous fasciculi, or into thin, transparent lamina, which cross and intersect one another in all directions, so as 
 to lesve interstitial cavities or areolie, freely communicating with each other, and moistened by an albuminous 
 fluid. The tissue thus formed, more properly called areolar, or filamentous, is of a grayish aspect, and highly 
 elastic ; the latter property depending not on any innate elasticity in the ultimate filaments, but on the sinuous 
 disposition of those filaments, and of the fasciculi into which they are collected. But few vessels, and still 
 fewer nerves, are believed to terminate in this tissue. It is continuous over the whole body ; hence the great 
 extent to which it may be affected with diffuse inflammation; it also invests and isolates parts, forms the ma- 
 trix of nearly all organs, and the basis of many membrane* ; and is called, according to its position, investing, 
 intermediate, penetrating, parenchymatous, or sub-membranous. The characters above described are most 
 strongly marked in the loose cellular tissue, examples of which are met with in the axilla, under the sub-scap- 
 ular muscle, between the free surfaces of muscles and their sheaths, behind the kidneys, &c. In other situ- 
 ations it is more condensed, as in the sub-serous, sub-mucous, and snb-cutaneoiis cellular tissues ; in the latter 
 of these, or the superficial fascia, and also in the cutis itself, it approaches to the fibrous tissue both in density 
 and in the mode of arrangement of its elementary filaments, and is therefore termed fibro-cellular tissue. 
 From this variety the transition is natural to the fibrous tissues, properly so called. 
 
 \n fibrous tissue the undulating primitive filaments are also arranged side by side into fasciculi, which diflTer 
 from those of cellular tissue in being much larger, more dense and more opaque, and in being straight in- 
 stead of flezuous. They are white, shining, strong, and almost inelastic, qualities depending on the compact 
 
SUPERFICIAL FASCIA. 297 
 
 PARTICULAR APONEUROSES. 
 Superficial Fascia. — Aponeuroses of the Cranium — of the Face — of the Neck — of the Thorax 
 — of the Abdomen — of the Pelvis — of the Thigh, Leg, and. Foot — of the Shoulder, Arm, 
 Forearm, and Hand. 
 
 The Superficial Aponeurosis, or Superficial Fascia. 
 
 From every point of the deep surface of the skin fibrous cellular lamellae arise, which 
 intersect each other in various directions, so as to form meshes or areolae, containing 
 adipose tissue in ordinary circumstances, and a serous fluid in cedema.* The cutaneous 
 muscle (panniculus carnosus) of the lower animals is developed in these laminae ; and 
 among them are situated the sub-cutaneous vessels and nerves, and the l)TTiphatic glands. 
 The name oi fascia superficialis has been of late applied to this assemblage of lamellae. 
 
 It was pointed out in a particular manner by Ghsson, who described it under the name 
 of the general investment of the muscles, proceeding from the spine, and covering the 
 whole body; Camper, Cowper, Scarpa, Hesselbach, Lawrence, J. Cloquet, &c., have 
 described it upon the abdomen, in its relation with herniae ; Godman has spoken of its 
 existence over the entire surface of the body : M. Paillard, in his inaugural dissertation, 
 traced it with still greater exactness ; MM. Velpeau and Blandin, in their Traites d^Ana- 
 tomie Chirurgicale, consider it as existing in almost all regions of the body. 
 
 But if the word aponeurosis be employed in its ordinary acceptation, it will be found 
 that a fascia superficifilis, consisting of a fibrous texture capable of anatomical demon- 
 stration, exists only in two kinds of situations, viz., in those where the skin is extreme- 
 ly movable, and in those where there is a layer of sub-cutaneous vessels and nerves : in 
 both these cases the fibrous prolongations from the skin are expanded into a thin lamina, 
 constituting a superficial covering for these vessels and nerves, and separated from the 
 fibrous investment of the muscles by a layer of cellular and adipose tissue, of variable 
 thickness. In all other parts, the fibro-cellular prolongations of the skin become contin- 
 uous either with the investing aponeuroses, or with the proper fibro-cellular sheaths of 
 the muscles, or are lost in the sub-cutaneous cellular tissue. So true is this, that this 
 thin areolar layer, which can with difficulty be separated from the skin in emaciated 
 persons, disappears altogether in those whose cellular tissue is distended by fat or se- 
 rous effusion. 
 
 Having made these remarks, I shall describe the superficial fascia in those regions 
 only where it can be easily demonstrated, viz., in the lower part of the abdomen, and in 
 the extremities. « 
 
 The Superficial Fascia of the Abdomen. 
 
 This aponeurosis, from its constituting the first sub-cutaneous covering of herniae, has 
 particularly engaged the attention of authors who have specially treated of the patho- 
 logical anatomy of those diseases. 
 
 It becomes evident in the neighbourhood of the umbilical region, but is much more dis- 
 tinct at the fold of the groin, where it divides into two layers, one of which is attached 
 to the femoral arch, and the other is prolonged upon the lower extremity. It is bound- 
 ed on the inside by the median line, and on the outside by another line, extending per- 
 pendicularly upward from the anterior superior spinous process of the ilium. It is pro- 
 longed over the inguinal ring, and over the spermatic cord in the male subject. 
 
 parallel disposition of the component filaments, and the slight amount of elasticily in particular on the ab- 
 sence of sinuosity in the compound fasciculi. According to the manner in which tliese fasciculi or fibres (as 
 they are termed) are arranged and combined, wo have either the membranous or the fascicular form of fibrous 
 tissues. 
 
 In the membranous form there are some which closely resemble the fibro-cellular memliranes already allu- 
 ded to, and consist of the shining fibres crossing each other in all directions (without anastomosis), and inter-* 
 mixed with more or less condensed cellular tissue ; for example, the thinner investing aponeurosis, the capsu- 
 lar ligaments, the pericardium, tunica albuginea, periosteum, and dura mater. In others, again, the fibres are 
 more parallel, though still intersected, and combined with cellular tissue, as in the fascia lata of the thigh, 
 and in other strong investing aponeuroses. In the aponeuroses of insertion of the broad muscles, and in the 
 expanded terminations of tendons, there is scarcely any cellular tissue, while the parallel arrangement is yet 
 more perfect ; and, finally, the latter attains its utmost perfection in the round ligaments, and in tendons, 
 which constitute the fascicular form of fibrous tissue, and the type of the tissue itself. 
 
 These textures contain but few nenes and vessels. The distribution of a branch of the fourth cranial nerve 
 to the dura mater, alluded to in the text, has been confirmed by other anatomists. Bloodvessels abound in the 
 periosteum, but they merely divide in that membrane, so as to enter the bone at a great numlier of points. 
 
 The sheaths of tendons (classed among the fibrous tissues by M. Cruveilhier) display a tendency to become 
 fibro-cartilaginous, especially at and near their attachments to the bones. They have fiitherto been described 
 (ex. gr., p. 250, 257) as if lined by vaginal synovial membranes (note, p. 177). According to Dr. Ifenl6, how- 
 ever, their interior is not covered by an epithelium. The bursa, or so-called bursal synovial membranes, formed 
 between the tendons of muscles (p. 265), between tendons and bones (p. 265, 266, 267), and between the skin 
 and projecting parts of bones, as over the patella, the olecranon, <&c., according to the same authority, are also 
 destitute of epithelium. It would appear, therefore, that although these cavities resemble in function the 
 true synovial membranes, they differ anatomically from them, and consist merely of shut sacs formed in the 
 Bfeneral cellular texture of the liody. Such bursie, however, as communicate with the synovial capsules of 
 oints (p. 216. 244), are probably lined by an epithelium.] 
 
 * [AdipoKc tissue is never deposited m the suli-cutaneous tissue of the eyelids, nor in the male onjan of tfcn- 
 «raliou. These lart", however, m-'V liecoine much distended from serous infiltration.] 
 
 Pp 
 
APONEUROLOGY. 
 
 It has been said that in the foetus, before the descent of the testicle, the superficial fas 
 cia dips into the inguinal canal, and forms an infundibuliform prolongation, reaching up 
 to the lower part of that gland ; and the dartos has been supposed to result from the ex- 
 pansion of this fascia — a description which can be regarded only as an ingenious specu- 
 lation, which has not been confirmed by actual dissection. 
 
 Lastly, the external surface of the superficial fascia of the abdomen is in relation with 
 the skin, separated from it, however, by a layer of adipose tissue of variable thickness, 
 in which the sub-cutaneous vessels and nerves are situated. Its deep surface corre- 
 sponds with the aponeurosis of the external oblique muscle, and with a portion of its 
 fleshy fibres : from these parts it is separated by a layer of serous cellular tissue, which 
 enables it to be moved easily upon this muscle and the sub-cutaneous vessels and nerves. 
 
 The Superficial Fascia of the Upper and Lower Extremities. 
 
 These are thin fibrous sheaths, separated from the skin by a greater or less quantity 
 
 of adipose tissue, and from the investing aooneurosis of the muscles by the sub-cutaneous 
 
 vessels and nerves. It does not exist around the joints, nor in the palms of the hands 
 
 and soles of the feet, for in these places the skin adheres to the subjacent aponeuroses 
 
 The Aponeuroses of the Cranium. 
 
 The Occipito-frorUal or Epi-cranial Aponeurosis. 
 
 This is a sort of tendinous or cutaneous cap {galea capitis), stretched between the two 
 frontal and two occipital muscles. Its superficial surface is intimately adherent to the 
 skin by means of very short and strong fibrous prolongations, between which the fatty 
 matter is deposited : the frontal, occipital, temporal, and auricular vessels and nerves 
 traverse this adipose tissue. Its deep surface glides upon the periosteum of the scull 
 (pericranium) by the intervention of a very delicate cellular tissue, in which fat is never 
 found. Its anterior margin receives the fibres of the frontal muscles, forming a trian- 
 gular point between them ; its posterior margin receives the fibres of the occipital mus- 
 cles, and also occupies the interval between them. These two muscles act as tensors 
 of the aponeurosis. Its outer margin gives attachment to the superior and anterior- 
 auricular muscles. It is composed behind of shining fibres, which seem to form a ten- 
 don of insertion to the occipitalis muscle, but it soon loses its pearly appearance, and 
 becomes more adherent to the skin : it is thick and strong at the upper part of the head, 
 but thin and almost cellular at the sides : it may be regarded as a dependance of the su- 
 perficial fascia. It gives rise to the tension which is so common and so dangerous in 
 inflammations of this region. Its adhesion to the skin explains the shallow character 
 of ulcers, and the flatness of the small abscesses occurring in these parts. 
 
 The Temporal Aponeurosis. 
 
 Besides the tendinous origin of the temporal muscle, which has been already descri- 
 bed, there is also a very strong investing aponeurosis, arising from the upper border of 
 the zygomatic arch, and inserted into the curved line bounding the temporal fossa above. 
 This aponeurosis completes the sort of case in which the muscle is contained ; and the 
 space between it and the temporal fossa corresponds with the thickness of the muscle. 
 
 It differs from the epicranial aponeurosis, which is more superficial and covers it su- 
 periorly, in not adhering to the skin, which glides very easily upon it. Its deep surface 
 adheres to the upper part of the muscle, and furnishes it with numerous points of at- 
 tachment ; below it becomes free, and is separated from the fleshy fibres by a consider- 
 able quantity of fat ; hence the depression formed in this situation in emaciated persons. 
 
 It increases in thickness from above downward ; it divides below into two layers : one 
 superficial and thinner, inserted into the outer edge of the upper border of the zj^goma ; 
 .the other deep and thicker, attached to the inner surface of that process. In tolerably 
 stout persons, a considerable quantity of fat is situated between these two layers, and a 
 remarkable branch of the temporal artery also occupies the same situation. This fat 
 must not be confounded with the larger mass which lies beneath the aponeuroses. The 
 resistance of this fascia explains the reason why abscesses in the temporal fossa never 
 point outward, but rather tend downward into the zygomatic fossa. 
 
 The Aponeuroses of the Face. 
 
 The Parotid Aponeurosis. 
 This is a sheath of great thickness, especially that part which covers the outer surface 
 of the gland ; it is continuous below with the cervical fascia. It belongs especially to 
 the gland, for which it forms a framework by means of fibrous prolongations from its 
 deep surface. The density of this sheath explains both the pain caused by inflammation of 
 the gland, and the difliculty with which pus makes its way from within it to the surface. 
 
 The Masseteric Aponeurosis. 
 This is a thin tendinous layer covering the masseter muscle, and continuous below 
 with the cervical fascia ; it appears to divide behind into two layers, one of which con- 
 
THE CERVICAJ. FASCIA, ETC. ^99^ 
 
 Stitntes the parotid fascia, and the other penetrates between that gland and the tiasse- 
 ter ; above and anteriorly, it becomes merged into the cellular tissue. Purulent matter 
 situated beneath this fascia tends downward into the neck, but when situated superfi- 
 cially to it, points towards the skin. 
 
 The Buccinator Aponeurosis. 
 The buccinator is covered by a closely adherent fibrous layer, which is regarded as tne 
 expansion of the fibrous sheath of the Stenonian duct ; it is thickest behind, where it is 
 termed the buccinato-pharyngeal aponeurosis, because it gives attachment behind to the 
 superior constrictor of the pharynx, and to the buccinator in front. This aponeurosis 
 prevents superficial abscesses from opening into the mouth, and is also opposed to the 
 extension outward of diseases attacking the mucous membrane. 
 
 The Cervical Aponeurosis, or Cervical Fascia. 
 In the cervical region we find, 1. The cervical fascia ; 2. The prevertebral aponeurosis 
 
 The Cervical Fascia. 
 
 The cervical aponeurosis covers the whole anterior region of the neck ; it extends 
 from the base of the lower jaw to the sternum and clavicles, and is insensibly lost on 
 either side in the sub-cutaneous cellular tissue. It is thick in the median line, and forms 
 a sort of cervical lima alba. From this linea alba two layers proceed in the supra-hyoid 
 region, and four in the infra-hyoid region, which are arranged in the following manner 
 
 1. The superficial layer, or the superficial cervical fascia, covers the whole anterior and 
 lateral regions of the neck, is prolonged downward in front of the clavicle, to become 
 continuous with the proper aponeurosis of the pectoralis major, is attached above to the 
 masseteric and parotid fasciae, and, internally to the masseter muscle, is fixed to the 
 base of the lower jaw. 
 
 It fills up the interval between the two platysmata, and is prolonged behind these mus- 
 cles to form the anterior layer of the sheath of the stemo-mastoid. The external jugu- 
 lar vein is superficial to this layer in the sub-hyoid, and lies beneath it in the supra-hyoid 
 region. 
 
 2. The deep layer passes beneath the stemo-mastoid, on the outer border of which it 
 unites with the preceding layer, and completes the sheath for that muscle. It covers 
 the internal jugular vein, the common carotid artery, the pneumogastric nerve, the great 
 sympathetic, and its cervical ganglia. Its upper margin is attached to the base of the 
 lower jaw ; its lower margin to the posterior surface of the clavicle, and to the posterior 
 edge of the fourchette of the sternum. It is necessary to examine this deep layer, both 
 in the supra and sub hyoid region. 
 
 In the supra-hyoid region its middle portion is very strong, and occupies the triangu- 
 lar space between the anterior bellies of the digastric muscles ; it is fixed by its lower 
 margin to the os hyoides, and on each side to the tendon of the digastricus. The lat- 
 eral portions of this aponeurosis pass beneath the sub-maxillary glands, and are attached 
 to the rami of the lower jaw. Externally to these glands they join the parotid aponeu- 
 roses, and form a tolerably thick septum between the sub-maxillary and parotid glands of 
 either side. 
 
 In the sub-hyoid region this deep layer is divided into three very distinct parts, a mid- 
 dle and two lateral. The middle is the stronger ; it occupies the triangular space be- 
 tween the two omo-hyoid muscles, and becomes continuous with their median tendons : 
 the muscles may, therefore, be regarded as the tensors of this facia. It binds down the 
 muscles of the infra-hyoid region : its arrangement explains why abscesses situated in 
 front of it discharge their contents through the skin, and not into the thorax, as those do 
 that are subjacent to it. The lateral parts of the aponeurosis constitute the supra-clavic- 
 ular fascia, a very strong layer, in which the superficial layer already described, and the 
 two which yet remain to be noticed, all terminate. It occupies the whole triangular 
 space between the trapezius and the stemo-mastoid, is continuous with the fibro-cellular 
 sheath of the former muscle, and adheres below to the clavicle. The latter circumstance 
 is of great importance in relation to surgical anatomy. 
 
 The superficial and deep layers which we have now described are common to both 
 the supra and sub hyoid regions. In the sub-hyoid region there are two other aponeurotic 
 layers : one, very thin, separating the superficial from the deep muscles, i. c, the omo 
 and sterno hyoidei from the sterno-thyroidei and thyro-hyoidei ; the other, thicker, pass- 
 ing between the sterno-thyroidei and the trachea. The latter is the fourth layer, which 
 Godman incorrectly describes as continuous with the pericardium. 
 
 The Prevertebral Aponeurosis. 
 
 This aponeurosis covers the muscles of the prevertebral region, viz., the longi colli, 
 
 and the great and small anterior recti : it is prolonged on each side upon the scaleni, the 
 
 levator anguli scapula;, and the brachial plexus ; and is attached to the upper border of 
 
 the scapula, and to the outer half of the posterior border of the clavicle. It completely 
 
^&b APONEUROLOGY. 
 
 separates the axilla from the neck, and is perforated by several vessels. It prevents 
 large abscesses of the neck from opening into the axilla ; and, in caries of the cervical 
 vertebrae, it retains the pus poured out against it, so as to form abscesses by accumulation. 
 
 The Thoracic Aponeuroses. 
 The Intercostal Aponeurosis. 
 Independently of the semi-tendinous structure of the intercostal muscles, we find sev- 
 eral fibrous layers in each intercostal space : one layer in front, continuous with the ex- 
 ternal intercostal muscle ; another behind, continuous with the internal intercostal mus- 
 cles ; and, situated within these muscles, a third layer, which lines them and separates 
 them from the pleura. The existence of this sub-serous aponeurosis accounts for the 
 rare occurrence of the bursting of an external abscess of the chest into the cavity of the 
 pleura ; and, on the other hand, of the escape of collections in the pleura by external 
 openings. 
 
 The Aponeurosis of the Serrati Postici. 
 In the dorsal region of the trunk, we find a very thin fibrous layer (sometiriies called 
 the vertebral aponeurosis), extending between the two serrati postici. It is of a quadri- 
 lateral form ; its inner margin is attached to the summits of the dorsal spinous process- 
 es ; its outer margin to the angles of the ribs, and its lower margin to the upper border 
 of the serratus posticus inferior ; it seldom terminates at the lower border of the serratus 
 posticus superior, but generally passes beneath it, and becomes the investing aponeuro- 
 sis of the splenius. The use of this aponeurosis is evidently to confine the posterior spi- 
 nal or long muscles of the back. 
 
 The Abdomistal Aponeuroses. 
 The parietes of the abdomen are partly muscular and partly aponeurotic : the muscu- 
 lar portions are situated at the sides of the abdomen. The aponeurotic portions occupy 
 the anterior and posterior regions, and form the anterior and posterior abdominal aponeu- 
 roses. The extensibility, elasticity, and, above all, the contractility of the abdominal pa- 
 rietes, depend on the three intersecting muscular layers ; while to the aponeuroses must 
 be attributed their capability of resistance and want of extensibility. 
 
 The Anterior Abdominal Aponeurosis. 
 
 The anterior abdominal aponeurosis forms the greater part of the anterior wall of the 
 abdomen. It consists, 1. Of a fibrous column, which is continuous with the osseous col- 
 umn of the sternum ; and, 2. Of two perfectly corresponding halves, one right, the other 
 left. These two halves are united in the linea alba, which may be regarded as their com- 
 mon origin. 
 
 The Linea Alba. 
 
 The linea alba {i,figs. 109, 110) is a tendinous raphe, extending from the ensiform 
 cartilage to the symphysis pubis ; it constitutes the anterior median line of the abdomen. 
 In a theoretical point of view it may be regarded as a continuation of the sternum, which, 
 in some animals, is prolonged as far as the pubes.* 
 
 Anatomists are not agreed as to the acceptation of the term linea alba. According 
 to some, it is a mathematical line produced by the intersection of the aponeuroses of 
 one side with those of the other : according to others — and this njeaning appears to me 
 preferable — it consists of the tendinous band comprised between the inner borders of the 
 recti. 
 
 Thus defined, the breadth of the linea alba corresponds to the interval between these 
 muscles, and, as they are directed somewhat obliquely upward and outward, it follows 
 that the upper or supra-umbilical portion of the linea alba is broader than that portion 
 which is below the umbilicus. This remarkable arrangement, by which the strength of 
 the lower part of the abdomen is secured, affords an explanation of the uniform occur- 
 rence of hernias through the linea alba above, not below, the umbilicus. It should also 
 be observed that, during exertion, the viscera are chiefly forced against the lower part of 
 the abdominal parietes, and also that the gravid uterus rests upon it. 
 
 The sub-umbihcal portion of the linea alba forms a mere line, while the supra-umbili- 
 cal is about a quarter of an inch in breadth. Its transverse dimensions are much in- 
 creased in persons whose abdomen has been greatly distended. Thus, during and after 
 pregnancy and certain dropsies, it in some cases acquires a considerable breadth, and 
 does not return to its original size, even after the distension has ceased to exist. In a 
 female who died a short time after delivery, I found the linea alba three inches across 
 at the umbilicus, and fifteen lines in the narrowest part. In cases of this kind, the linea 
 alba forms a sort of long pouch, which receives the intestines, and becomes very prom- 
 inent during the contraction of the recti. 
 
 The linea alba presents several elliptical openings for the passage of nerves and ves- 
 
 * The anal.ip.v has pveu bpen cnrried so far, that the tendinous intersections of the recti have been C«a» 
 JtarecJ to the ri'.is, Tt tht>y seeiii to ciime off from the linea alba like abdominal ribs. 
 
THE ANTERIOR ABDOMINAL APONEUROSIS. 301 
 
 sels. In these foramina, round masses of fat are developed, which dilate them, and draw 
 down the peritoneum into them, or are absorbed in consequence of emaciation, and thus 
 open an easy way for the production of hernia of the linea alba. Of all these orifices, 
 the most remarkable is the umbikcal ring, which gives passage to the umbilical vessels in 
 the foetus, but becomes cicatrized after birth, at least in the majority of subjects.* 
 
 The situation of the umbilicus varies at different ages. The middle point of the length 
 of the body is situated above the umbilicus before the sixth month of foetal existence, 
 and corresponds with it after that period. In the adult it is situated below the umbil- 
 icus. Its situation with regard to the abdomen varies in different individuals. Thus, 
 the umbilical cicatrix, which is generally a little below the middle of the abdomen, is 
 sometimes exactly in the middle. I have even seen it at the/ point of junction of the 
 lower with the upper two thirds. 
 
 This cicatrix, moreover, is much stronger than the neighbouring parts. Thus, an 
 umbilical hernia, which, in a new-born infant, always occupies the navel itself, in an 
 adult is almost invariably situated a little above the umbilicus. Still it occasionally 
 yields, either in cases of dropsy or of hernia ; and I have records of several instances of 
 hernia in the adult, that have occurred through the umbilical ring. 
 
 The linea alba is in relation, in front, with the skin, which adheres more closely to it 
 than to the neighbouring parts, especially opposite the umbilicus. In the, male, it is sep- 
 arated from the skin below by th,e suspensory ligament of the penis, which sometimes 
 extends as far as the middle of the space between the pubes and the umbilicus : behind, 
 it is in relation with the peritoneum, separated from it, however, by the remains of the 
 urachus, and by the bladder itself, when that viscus is distended. It is, then, through 
 the linea alba that the bladder is punctured in cases of retention of urine, and that the 
 incision is made in the high operation of lithotomy. The peritoneum does not adhere 
 more closely to the umbilicus than to the other parts of the abdomen, and therefore um- 
 bilical hemiae, like all others, are invariably provided with a proper sac. 
 
 The upper extremity of the linea alba is attached to the ensiform appendix, a flexible, 
 elastic, cartilaginous body, constituting, as it were, a transitional structure between the 
 sternum and the part we are now describing. 
 
 The lower extremity corresponds to the symphysis pubis. 
 
 If we examine the structure of the linea alba, we shall see that it is formed by the in- 
 tersection of the layers of the anterior abdominal aponeuroses. One remarkable circum- 
 stance is, that the intersecting fibres do not stop at the median line, but pass from one 
 side to the other ; so that the tendinous fibres of the external oblique of the right side 
 become the tendinous fibres of the internal oblique of the left ; and, again, that the inter- 
 section occurs not only from side to side, but also from before backward. Below the 
 umbilicus the point of intersection is elevated by some longitudinal fibres, constituting 
 a small and very distinct cord, which appears to form a septum between the recti mus- 
 cles ; it increases in thickness as it proceeds downward from the umbilicus to the sym- 
 physis, and may be easily felt under the skin in emaciated individuals. We may add, 
 that the fibres of the linea alba have no resemblance to the yellow elastic tissue ; they 
 are neither extensible nor elastic, at least in the human subject. Its uses entirely re- 
 fer to its capability of offering resistance. 
 
 The pyramidales are its tensor muscles. 
 
 The Four Layers of the Anterior Abdominal Aponeurosis. 
 
 From each side of the linea alba {a, Jig. 134, a diagram representing a horizontal sec- 
 tion of the abdominal parietes) two fibrous layers proceed Fig. 134. 
 out'vard, one anteriorly, the other posteriorly, to the rec- 
 tus muscle (r). 
 
 The anterior layer (b), having arrived near the outer bor- 
 der of the muscle, subdivides into two other layers : one 
 superficial, constituting the aponeurosis of the external ob- 
 lique (d) ; the other deep, forming the anterior layer of the 
 aponeurosis of the internal oblique (e). The posterior lay- 
 er (c) is also simple as far as the outer border of the rec- 
 tus, and then separates likewise into two layers : one an- 
 terior, which becomes united with the aponeurosis of the 
 internal oblique (e), and is regarded as the posterior layer 
 of that aponeurosis ; the other posterior, which continues 
 its course outward from the rectus, and forms the aponeu- 
 rosis of the transversaUs muscle (/). We shall describe 
 these different parts in succession. 
 
 The Aponeurosis of the External Oblique. — This is the most superficial layer, and is 
 )f a quadrilateral figure {a, fig. 109) ; it is broad below, where it corresponds to the in- 
 
 * Some cases are on record of the persistence of the umbilical vein, and, consequently, of the umbilical ring. 
 I have nariated a case where a sub-cutaneous abdominal vein, prodigiously developed, became continuous with 
 the vena cava, which was also very large. — {Anat. Path., 1. xvi., pi. 6.) 
 
APONEUROLOGY. 
 
 terval between the anterior superior spinous process of the ilium and the linea alba, be- 
 comes narrower immediately above, and again expands at the upper part, but to a less 
 extent than below. 
 
 It is covered by the skin and the superficial fascia, and it covers the aponeurosis and 
 the anterior portion of the fleshy fibres of the internal oblique. It adheres intimately to 
 the aponeurosis of the internal oblique, as far as the vicinity of the outer border of the 
 rectus, excepting below, where the two fasciae are perfectly distinct, and can be easily 
 separated throughout their entire extent. 
 
 Its external margin, slightly concave and denticulated, presents irregular prolongations, 
 with which the fleshy fibres become continuous. A line extending from the anterior 
 superior spinous process of the ilium to the extremity of the cartilage of the eighth rib, 
 will indicate with tolerable accuracy the direction of this margin, which appears to be 
 divided into two layers, one superficial, very thin, and continuous with the proper cel- 
 lulo-fibrous sheath of the muscle ; the other deep, and giving origin to fleshy fibres. 
 
 Its upper margin is narrow, and cannot be exactly defined ; it often gives attachment 
 to some fibres of the pectoralis major. 
 
 Its lower margin consists of two very distinct portions : one, extending from the ante- 
 rior superior spinous process of the ilium to the spine of the os pubis, is called the fem- 
 oral arch (p p',figs. 136, 137) ; the other, stretching between the spine and the symphy- 
 sis pubis, offers for consideration the pillars and the cutaneous orifice of the inguinal 
 canal (m, figs. 109, 136, 137). 
 
 The aponeurosis of the external oblique is composed of tendinous fasciculi, directed 
 obliquely downward and inward, like the fleshy fibres with which they are continuous. 
 It is also perforated, especially in the neighbourhood of the linea alba, by a considerable 
 number of bloodvessels and nerves. Not unfrequently the component fasciculi have 
 between them, especially near the femoral arch, linear or triangular spaces of variable 
 size, through which the fibres of the internal oblique are visible. The component fas- 
 ciculi are also intersected at right angles, and, as it were, bound down by other tendi- 
 nous fibres, which are more or less developed in different individuals, and are most usu- 
 ally situated in the neighbourhood of the femoral arch. 
 
 Having made these preliminary observations, we shall now describe in detail, 1. The 
 lower margin of the aponeurosis of the external oblique, or the femoral arch; and, 2. The 
 inguinal ring and canal. 
 
 Th& Femoral or Crural Arch. — ^When the aponeurosis of the external oblique has ar- 
 Fig. 136. rived opposite a line extending from 
 
 the anterior superior spinous pro- 
 cess of the ilium to the spine of the 
 pubes, it suddenly terminates, be- 
 comes thickened, and is reflected 
 (a a', fig. 137) from before back- 
 ward upon itself The reflected 
 border {pp',figs. 136, 137) has been 
 variously denominated the femoral 
 or crural arch, the reflected margin 
 of the teiidon of the external oblique, 
 PouparVs ligament, and the ligament 
 of Fallopius. , This arch, which is 
 stretched like a cord, corresponds 
 to the fold of the groin, and defines 
 the limits of the abdomen and the 
 lower extremity : it forms the ar 
 terior border of a considerable tri- 
 angular space, which is completed 
 by the ilium (I, fig. 136) on the out- 
 side, and by the os pubis (2) behind. 
 This space establishes a communi- 
 cation between the lower extremi- 
 ty and the abdomen, and is occupied (proceeding from without inward) by the psoas and 
 aiacus muscle (» to i), the crural nerve (n), the femoral artery (a) and vein {v), and the 
 pectineus muscle.* 
 
 The crural arch is directed somewhat obliquely downward and inward ; and as its out- 
 er third is more oblique than the inner two thirds, it describes externally a slight curve, 
 having its concavity directed upward. Its lower or reflected border is continuous with 
 the fascia of the thigh. This adhesion occasions the tension of the arch, as may be 
 shown by cutting the femoral fascia at the point of its junction with the arch : hence 
 the precept of Scarpa, who recommended incisions to be made in this situation, in order 
 to relieve the constriction in femoral hernise. 
 The free margin of the reflected portion of the aponeurosis, of which the femoral arch 
 
 * This is not represented in the woodcut. 
 
 
 ^^ 
 
THE CRURAL ARCH. 303 
 
 consists, is continued backward into the iliac fascia («') externally ; and internally, into 
 the fascia transversalis (t). 
 
 Externally near the psoas and iliacus (beyond a', fig. 137), the posterior or reflected 
 portion of the arch is closely blended with its anterior or direct portion, as well as with 
 the iliac fascia and the fascia of the thigh, so that, in this situation, there is a thickening 
 rather than an actual reflection of the aponeurosis. Internally to the psoas and iliacus, 
 however (at a), the direct and reflected portions are perfectly distinct, and form a groove 
 with its concavity upward, which we shall find to assist in the formation of the inguinal 
 canal. These two separate portions of the inner part of the femoral arch require a spe- 
 cial description. 
 
 The direct portion (part of which is shown turned downward at d, fig. 137) passes on 
 to be attached to the spine of the pubes (p,figs. 136, 137), becoming more and more 
 prominent, so that it can be easily felt under the skin, especially when the thigh is ex- 
 tended upon the pelvis. The reflected portion, externally, is narrow, and, as it were, 
 folded ; but internally it becomes expanded, from its fibres slightly changing their direc- 
 tion, and diverging, so as to be inserted into the spine of the pubes behind the direct 
 portion, and also into the pecten or crest of the pubes. 
 
 This reflected and expanded portion, described even in the oldest anatomical works, 
 has become celebrated in recent times under the improper name of Gimbernat's ligament 
 {g,fig. 136), from a Spanish surgeon, who pointed out its importance as the seat of stric- 
 ture in femoral hernia. It is triangular in shape ; its anterior margin corresponds to the 
 crural arch ; its posterior margin to the crest of the pubes ; its outer margin is free, con- 
 cave, tense, and sharp, and forms the inner part of the circumference of the crural ring 
 (r). This concavity, against which the protruded intestine becomes strangulated, has 
 obtained for the ligament the name of the falciform ligament or fold.* Its strength is 
 very considerable ; but, occasionally, intervfds are left between its fibres, through which 
 hernial protrusions may take placet 
 
 From the lower surface of Gimbernat's ligament a fibrous prolongation is given off, 
 which sometimes represents a second arch below the femoral arch, and assists in form- 
 ing the superficial layer of the fascia lata of the thigh. This tendinous expansion has a 
 great effect in rendering the arch tense. We may add, that there is considerable vari- 
 ation in different subjects, both in the strength and development of Gimbernat's liga- 
 ment ; varieties that must have great influence on the position of crural herniae, and on 
 the seat of strangulation in that disease. Behind the femoral arch, on the outer side of 
 Gimbernat's Ugament, is an opening (a to r,fig. 136) or rkig, intended to give passage to 
 the femoral artery (a) and vein (v), and to a great number of lymphatic vessels and glands : 
 this is the crurcU ring.X The sub-peritoneal cellular tissue sometimes acquires great 
 strength opposite this ring, and constitutes what is called the crural septum (situated at r). 
 The form of the crural ring is that of an isosceles triangle, the base of which is very 
 long, and formed by the cniral arch, the inner border by the pectineus, and the outer by 
 the psoas and iliacus muscles. Of the three angles, the internal is rounded, and corre- 
 sponds to the concave margin of Gimbernat's ligament ; the external angle, opposite 
 which the epigastric artery is situated, is very acute, and corresponds to the point at 
 which the femoral arch separates from the iliac fascia ; the posterior angle is very ob- 
 tuse, and corresponds to the ilio-pectineal eminence {d). 
 
 The femoral vein is in relation with the inner or pectineal border of this triangular 
 space ; the femoral artery with the ilio-pectineal eminence and the outer border. The 
 crural nerve («) lies behind and externally to the artery, being separated from it only by 
 the iliac fascia («')• Crural herniae descend through the inner portion of the crural ring.^ 
 
 The femoral arch is formed by proper fibres, arising from the anterior superior spinous 
 process of the ilium ; and also by those fibres of the aponeurosis of the external oblique, 
 which, after having arrived at the arch, change their direction, become reflected inward, 
 and are collected together, so as to form a strong and tense cord. 
 
 The Inguinal Ring and Canal. — On the inner side of the spine of the os pubis, between 
 the spine and the symphysis, the aponeurosis of the external oblique divides into two 
 almost parallel, or at least very slightly diverging, bands, which leave between them an 
 opening for the passage of the spermatic cord in the male, and of the round ligament in 
 the female. This opening is the inguinal ring {m,figs. 109, 136, 137), and the bands 
 which form its limits are called the pillars (o p, figs. 136, 137). The inguinal ring is oval 
 or triangular ; its greatest diameter has the same direction as the fibres of the external 
 obUque, viz., obliquely downward and inward. Its base corresponds to the interval be- 
 
 * tTnis term is now generally applied (after Bums) to the external margin of the saphenous opening {n,Jig. 
 137) in the fascia lata.] 
 
 t M. Laugier has lately recorded a case of hernia through the fibres of Gimbernat's ligament. I have since 
 had an opportunity of seeing, in an old woman at the Salptr^iere, two hernial sacs near each other, one of 
 which protruded through the crural ring, and the other internally to the ring; the necks of these sacs wer« 
 separated by a fibrous band, which appeared to me to be formed by the external fibres of Gimbernat's ligament. 
 
 X [The term " crural ring," it must be remembered, is limited by British anatomists and surgeons to the 
 small space (r), bounded internally by the free margin of Gimbernat's ligament, and externally by the femora] 
 vein. It is through this space, and therefore through the internal portion only of the " crural ring" of M 
 CrUTcilhier, that crural hemiEB descend.] I) See note, supa. 
 
304 
 
 APONEUftOLOGY. 
 
 Fig. IS". tween the spine and 
 
 symphysis pubis. Its 
 apex is not always 
 well defined, and is 
 generally truncated 
 by fibres which pass 
 at right angles to its 
 pillars. From the up- 
 per part of the margin 
 of the ring a tendi- 
 nous prolongation is 
 given off, which ac- 
 companies the sper- 
 matic cord in the 
 male, and the round 
 ligament in the fe- 
 male. 
 
 Of the pillars, one 
 is external or inferior, 
 the other internal or 
 superior. The external 
 pillar (p) is attached, 
 not to the spine of the 
 
 OS pubis, but into the fore part of the symphysis : this pillar is nothing more than the in- 
 ternal extremity of the direct portion of the femoral arch. Moreover, some anatomists 
 consider Gimbemat's ligament as the reflected portion of the external pillar. The internal 
 pillar (o) is broader than the external, and intersects the corresponding structure of the 
 opposite side in front of the symphysis, not unfrequently some fibres of the right internal 
 pillar intersecting those of the left external pillar. 
 
 Inguinal Canal or Passage. — The inguinal ring^ {m) is the anterior or cutaneous orifice 
 of an oblique passage, formed in the substance of the lower edge of the inferior parietes 
 of the abdomen opposite the crural arch, and destined to transmit the cord (s) of the 
 spermatic vessels in the male, and the round ligament of the uterus in the female. This 
 passage, which modern writers only have correctly described, has been styled by them 
 the inguinal canal (i c wi). Its length varies from an inch and a half to two inches and a 
 half; it is directed obliquely downward, forward, and inward. 
 
 The inguinal canal is formed, in reality, by the groove resulting from the reflection 
 backward of the aponeurosis of the external oblique (at a), the posterior border of which 
 groove is continuous with the fascia transversalis, and its anterior border with the apo- 
 neurosis of the external oblique itself We may, then, consider this passage as having 
 an inferior concave wall (at a) formed by the groove of reflection ; an anterior wall, formed 
 by the aponeurosis of the external oblique (shown turned downward at d) ; and a posterior 
 wall, formed by the fascia transversalis (c). There is no superior wall, or, rather, it is sup- 
 plied by the lower margins of the internal oblique (c) and transversalis (/) muscles, 
 which occupy the groove of the crural arch, and receive from it externally numerous 
 points of attachment. Internally the margins of these muscles are separated from the 
 groove by the spermatic cord, or the round ligament. It has been supposed that this 
 canal is lined by a funnel-shaped prolongation of the fascia transversalis. The peritoneal 
 or interrml orifice (t, figs. 110, 137) of the inguinal canal is much less accurately defined 
 than the external, or, rather, its inner border alone is well defined, consisting of a concave 
 fibrous edge fonned by the fascia transversalis, and somewhat analogous to the concave 
 edge of Gimbemat's ligament. The strangulation of the intestine in inguinal hernia 
 sometimes occurs against this edge. The peritoneal orifice of the inguinal canal is closed 
 by the peritoneum, and the epigastric artery runs aloug its inner border. 
 
 The testicle, which is originally situated within the abdomen, descends through the 
 inguinal canal ; so, also, do those herniae, commonly called oblique inguinal hemis, in 
 order to distinguish them from the direct or internal inguinal herniae. 
 
 The Anterior Aponeurosis of the Obliquus Internus and Transversalis. — The aponeurosis 
 of the internal oblique commences at the linea alba, and immediately divides in its upper 
 three fourths into two layers, one of which passes in front, and the other behind the rectus 
 (r, fig. 1 34). The lower fourth passes entirely in front of the same muscle without division 
 (as shown in^^. 135). The anterior layer is very closely united with the aponeurosis of 
 the external oblique (at b), from which it can be distinguished only by the direction of 
 its fibres. In some parts there is even a true interlacement between the tendinous fibres 
 of these two muscles ; the lower or undivided portion of the aponeurosis of the internal 
 oblique may, on the contrary, be easily separated from that of the external oblique. The 
 posterior layer of the aponeurosis of the internal oblique is no less intimately blended with 
 that of the transversalis (at c), from which, also, it is to be distinguished by the direction 
 of its fibres only. At the outer border of the rectus muscle the anterior layer of the apo- 
 
THE FASCIA TRANSVERSALIS, ETC. 305 
 
 aeuroFis of the internal oblique separates from that of the external oblique, and the pos- 
 terior .ayer from that of the transversalis, and then immediately unite together, and give 
 origin to the fleshy fibres. The outer margin, therefore, of the aponeurosis of the internal 
 oblique exactly corresponds to the outer border of the rectus, and is directed vertically. 
 The aponeurosis of the transversalis (/, Jigs. 134, 135) is the deepest layer of the an- 
 terior abdominal aponeurosis : it is very narrow above, increases in breadth as far down 
 as opposite the crest of the ilium, and then progressively diminishes towards its lower 
 portion. It commences at the linea alba, and is divided into two portions : one inferior 
 (below s,Jig. 110), consisting only of the lower fourth of the aponeuroses, and passing in 
 front of the rectus (as in Jig. 135) ; the other superior (above s, Jig. 110), which passes 
 behind the rectus (as in^^. 134), and is formed by the upper three fourths of the apo- 
 neurosis. Its external margin is convex, and gives origin to the fleshy fibres of the 
 muscle. Its anterior surface is closely united to the aponeurosis of the internal oblique, 
 beyond which it passes on the outside : its posterior surface is loosely connected with 
 the peritoneum, excepting in its lower fourth, which, as already stated, passes in front 
 of the rectus muscle. The tendinous fibres of the transversalis, which have the same 
 direction as its fleshy fibres, are occasionally found not to terminate abruptly behind the 
 lower part of the rectus ; but the aponeurosis merely becomes thinner, and its fasciculi 
 separated from each other. 
 
 The Fascia Transversalis and Sub-peritoneal Aponeurosis, 
 
 In order to complete the description of t"he anterior abdominal aponeurosis, it only re 
 mains for me to describe the fascia transversalis, which I regard as a thickened portion 
 of the sub-peritoneal fascia. 
 
 The fascia transversalis (seen at a' and c,Jig. 137) was first pointed out by Sir Astley 
 Cooper, but has been more correctly described by Lawrence and J. Cloquet : it com- 
 mences below at the reflected border (a a') of the crural arch, so that it may be regard- 
 ed as a thin prolongation of the reflected portion of the tendon of the external oblique. 
 It also frequently arises from the brim of the pelvis, as well as from the crural arch. 
 From these points it passes upward, becoming more and more attenuated as it approach 
 es the umbilicus, at which point it cannot be distinguished from the sub-peritoneal apo- 
 neurosis. 
 
 The fascia transversalis is situated between the abdominal muscles and the peri- 
 toneum. Its internal margin is continuous with the outer border of the rectus muscle ; 
 and its external margin, which gradually becomes thinner, is blended with the sub-peri- 
 toneal aponeurosis. The only part deserving a special description is that portion which 
 lies between the outer border of the rectus muscle and the abdominal opening of the in- 
 guinal canal. In this situation it assists in strengthening the parietes of the abdomen, 
 which are here remarkably weak ; and it is to the existence of this fascia that we may 
 attribute the extreme rarity of direct inguinal hemiae*, which, in fact, can only result 
 from a congenital weakness, or a relaxation of this fascia. 
 
 A very interesting portion of the fascia transversalis is an infundibuliform prolonga- 
 tion, given off from it to the spermatic cord. It is impossible, indeed, to conceive the 
 descent of the testicle to occur without its pushing before it a portion of the fascia, 
 which then constitutes the immediate investment of the cord upon which the cremaster 
 muscle {b,Jig. 137) is spread out. The peritoneal orifice of the inguinal canal is, there- 
 fore, the superior opening of the infundibuliform process, furnished by the fascia trans- 
 versalis to the testicle and its cord. 
 
 The Sub-peritoneal Aponeurosis. 
 The peritoneum, throughout the whole extent of the abdominal parietes, is strength- 
 ened on its outer surface by a very thin tendinous layer, the existence of which may 
 serve to explain why abscesses, formed in the parietes of the abdomen, so seldom open 
 into the cavity of the peritoneimi ; and, on the other hand, why collections within the 
 peritoneal cavity so seldom open externally. 
 
 The Posterior Abdominal Aponeurosis. 
 The posterior abdominal aponeurosis is much smaller and of less importance than the 
 anterior : it consists of three layers, one anterior (Ji, in diagram,/^. 134), and very thin, 
 which commences at the base of the transverse processes of the lumbar vertebrae, and 
 passes in front of the quadratus lumborum {q) ; another, middle («), and much stronger, 
 commencing at the summits of the same transverse processes, and passing behind the 
 quadratus lumborum ; and a third, posterior (k), which arises from the summits of the 
 lumbar spinous processes, and passes behind the sacro-lumbalis, longissimus dorsi, and 
 transverso-spinalis muscles («). This last-mentioned layer is connected both with the 
 internal oblique (e) and with the transversalis muscle (/), and is blended with the apo- 
 neuroses of the serratus posticus inferior, and of the latissimus dorsi (/). The two an- 
 
 * [/. e., herniiE occurring directty downward and forward throagh the inguinal ring {.rn,jig. J 37), and not 
 descending along the inguinal canal.l 
 
 Qq 
 
306 APONEUROLOGY. 
 
 terior layers are connected with the transversalis only. The posterior abdominal apo- 
 neurosis has, therefore, nearly the same relation to the quadratus lumborum and the 
 common mass of the sacro-lumbalis, longissimus dorsi, and transverso-spinalis muscles, 
 that the anterior aponeurosis has to the rectus muscle. 
 
 The Lumho-iliac Aponeurosis. 
 
 The lumbo-iliac aponeurosis, or fascia iliaca of modem authors, forms the tendinous 
 sheaths of the abdominal portion of the psoas and ihacus muscles, and is, therefore, bi- 
 furcated at its upper part. That portion which invests the psoas commences at the ten 
 dinous arch of the diaphragm, already described as embracing the upper end of this mus- 
 cle. The iliac portion arises from the whole extent of the inner border of the crest of the 
 ilium. The circumflex ilii artery is situated in the substance of this iliac portion, at its 
 origin. The internal margin of the fascia iliaca is attached to the sides of the lumbar 
 vertebrae, and, lower down, to the brim of the pelvis ; it is arranged in arches, which 
 give passage to the lumbar vessels and to the nervous cords, establishing a communica- 
 tion between the lumbar plexus and the lumbar ganglia of the sympathetic nerve. The 
 centre of each arch is opposite to the groove on one of the bodies of the lumbar verte- 
 brae, the intervals between the arches corresponding with the intervertebral substance. 
 The largest arch extends from the last lumbar vertebra to the brim of the pelvis, and is 
 opposite to the base of the sacrum. The obturator and lumbo-sacral nerves pass under it. 
 
 Opposite the femoral arch, the fascia iliaca adheres intimately to the outer part of 
 Poupart's ligament ; but towards the median line it separates from that ligament, passes 
 behind the femoral vessels, and forms the posterior half {s,Jig. 136) of the crural ring. 
 
 Below the femoral arch, the fascia is prolonged upon the thigh ; on the outside («') it 
 completes the sheath of the psoas and iliacus, accompanies them as far as the lessei 
 trochanter, and becomes continuous with the iliac portion {g, fig. 137) of the femoral 
 fascia ; on the inside, it forms the posterior wall (s, fig. 136) of the canal for the femoral 
 vessels, and forms the deep layer or pubic portion {h,fig. 137) of the femoral fascia. 
 
 Relations. — It lies beneath the peritoneum, to which it is united by a very loose cellu- 
 lar tissue ; it covers the psoas and iliacus, but is not adherent to them, in consequence 
 of the interposition of some equally delicate cellular tissue. All the nerves from the 
 lumbar plexus are subjacent to this fascia, excepting one very small cord, which perfo- 
 rates it at the side of the sacrum, and becomes situated in the sub-peritoneal cellulai 
 tissue. The femoral vessels are situated on the inner side of the fascia, and are separ- 
 ated by it from the crural nerve, which lies on its outer side, and underneath it. 
 
 Structure. — The upper part of the fascia is extremely thin, but it increases in thick- 
 ness as it approaches the femoral arch. It is formed of well-marked transverse fasci- 
 culi, intersected perpendicularly by the tendon of the psoas parvus, when that muscle 
 exists. This tendon is blended with the fascia, and is distinguished from it only by the 
 different direction of its fibres ; it is inserted by spreading out, at the side of the pelvic 
 brim, into a tendinous arch which lines this brim, and with which the psoas parvus and 
 the iliac fascia are continuous above, and the pelvic fascia below. 
 
 Few aponeuroses are more deserving the attention of anatomists than this, on account 
 of the practical consequences resulting from its arrangement. In fact, notwithstanding 
 its tenuity, it forms a boundary between the sub-peritoneal and sub-aponeurotic cellular 
 tissue, which is very rarely passed by inflammatory action. When inflammation termi- 
 nates in suppuration, the pus, whether it be beneath the peritoneum or beneath this fas- 
 cia, descends towards the femoral arch ; but if the inflammation be sub-peritoneal, the 
 femoral vessels lie behind the purulent collection ; and should it be sub-aponeurotic, the 
 vessels will be in front of it. The latter is especially the case in abscesses following 
 caries of the vertebrae. 
 
 The Aponeuroses of the Pelvis. 
 
 The aponeuroses of the pelvis should be distinguished into the pelvic, properly so called, 
 and the perineal : the former constitute essential parts of the pelvis, and are deeply seat- 
 ed. The others belong to that part of the floor of the pelvis which is called the perineum. 
 I shall commence with the description of the latter. 
 
 The Aponeuroses of the Perineum. 
 
 These are two in number ; one superficial, the other deep. 
 The Superficial Perineal Fascia.* 
 
 Dissection. — Remove tne sub-cutaneous adipose tissue very cautiously, layer by layer, 
 commencing the dissection along the edges of the pubic arch. 
 
 This aponeurosis (which is very distinct from the fibrous laminae, intercepting spaces 
 filled by fat, and forming what is called the fascia superficialis) is of a triangular shape, 
 and consists of well-marked transverse fibres. The outer margin of each half of the fas- 
 cia is attached to the descending ramus of the os pubis and the ascending ramus of the 
 ischium : its inner margin is lost at the raphe, along the median line : its posterior maX' 
 
 * M Bouvier, in his thesis, and M. Blandin, in his Traiie d'Anaiomie Chirurgicale, first described this fascia 
 
THE DEEP PERINEAL APONEUROSIS. 
 
 807 
 
 Fig. 138. 
 
 ^a IS bounded by a line extending from the tuberosity of the ischium to the anus ; it cor- 
 responds with the posterior edge of the transversus perinei muscle, and appears to be 
 reflected behind it, so as to line the corresponding perineal or ischio-rectal fossa.* 
 
 Relations. — It is covered by a prolongation of the dartos, to a greater extent in the me- 
 dian line than on each side ; also by the sub-cutaneous adipose tissue, which is thicker 
 behind than in front, and by the sphincter ani, above which it terminates in the median 
 line : it covers the transversus, the bulbo-cavernosus, and the ischio-cavernosus mus- 
 cles, the fibrous sheaths of which may even be regarded a^ a prolongation of this aponeu- 
 rosis. It also covers the superficial perineal vessels and nerves, which are sometimes 
 lodged within its substance. The existence of this membrane explains why, in cases 
 of perforation of the urethra, the urine is infiltrated forward, and very rarely backward. 
 The Deep Perineal Aponeurosis. 
 
 Dissection. — Remove with great care the ischio- and bulbo-cavernosus and the trans- 
 versus perinei muscles. 
 
 This aponeurosis, which was well described by M. Carcassone under the name ofpe. 
 rineal ligament, and called by 
 modern writers the middle pe- 
 rineal fascia, appears to me 
 perfectly distinct from the 
 aponeuroses of the pelvis. It 
 is an extremely strong trian- 
 gular layer {b a, fig. 138t), oc- 
 cupying the pubic arch, and 
 apparently forming a continu- 
 ation of the sub-pubic ligament 
 (jb). It is vertical near the 
 arch, as far as the ball of the 
 urethra, below which it be- 
 comes horizontal, or, rather, 
 oblique, from before back- 
 ward. Its lateral margins are 
 attached to the descending ra- 
 mi of the ossa pubis, and the 
 ascending rami of the ischia 
 {d, d), above the attachment of 
 the ischio-cavernosi muscles. Its posterior margin becomes blended with the posterior 
 margin of the superficial perineal fascia, behind the transversi muscles, in front of the 
 perineal fossse, of which it forms the anterior boundary. 
 
 Relations. — Its lower surface is in relation with the ischio- and bulbo-cavernosus mus- 
 cles, and gives off, in the median line, a fibrous septum, which passes between these 
 muscles, and affords them points of attachment. Its upper surface is in relation with 
 the artery or arteries (e e) of the bulb, which are sometimes contained within its sub- 
 stance : it is also in contact with a very remarkable plexus of large veins, with which it 
 is very closely united, so that, when divided, they remain open : these veins are also fre- 
 quently enclosed within its substance. It is also in relation with the levator ani. 
 
 There constantly exists another transverse muscle, very distinct from the transversus 
 perinei generally described, which is situated farther behind. This muscle (transversus 
 perinei alter. Alb.) is applied to the lower surface of the perineal fascia, and passes trans- 
 versely inward to the bulbous portion of the urethra. 
 
 The deep fascia of the perineum is perforated (at c) by the posterior part of the bulb 
 of the urethra, or, rather, by the point of union (c, fig. 181) between its bulbous and 
 membranous portions : it gives off prolongations upon the sides of the bulb, and serves 
 to support the membranous portion of the urethra : whence the name, triangular liga- 
 ment of the urethra, given to it by CoUes. It is also perforated, beneath the arch of the 
 pubes, by a great number of veins, and by some arteries. 
 
 Uses. — This remarkable aponeurosis evidently supports the canal of the urethra. It 
 has been correctly regarded as an obstacle to the introduction of the catheter, the point 
 of which strikes against it, however slightly it may deviate from the direction of the ca- 
 nal. The prostate gland is situated above it. 
 
 The Pelvic Jlponeuroses. 
 From the sides of the pelvis, and from the entire circumference of the brim (which, as 
 
 * Sec note, p. 309. 
 
 t [The triangular liganfient consists of two layers, which approach each other more ne.irly above tliati below . 
 m^g- 138, the anterior layer has been removed. Between the two layers are situated the sub-pubic ligamoa 
 (A), perforated by the vena dorsales penis, the pudic arteries (//), the arteries of the bulb (e e), the g^eat 
 part of the membranous portion of the urethra, with its comjjressor muscle, to be described hertaftiir, an. 
 lastly, Cowper's glands (g g). In the female, the triingular ligament is perforated by the vagina, as wel 
 bv the urethra.] 
 
308 APONEUROLOGY. 
 
 we have seen, is covered and rendered smooth by a thick layer of fibrous tissue, that 
 forms a hmit to the lumbo-iliac aponeurosis), a tendinous lamina is given off, which pass- 
 es into and lines the pelvis, and is soon divided into two distinct layers : one external, 
 the lateral pelvic or obturator fascia, which continues to line the sides of the pelvis, and 
 covers the obturator intemus muscle ; the other internal, or superior, which passes in- 
 ward upon the side of the prostate gland, bladder, and rectum, in the male, and of the 
 bladder, vagina, and rectum, in the female, in order to form the floor of the pelvis. This 
 IS the superior pelvic aponeurosis, with the description of which we shall commence. 
 
 The Superior Pelvic Aponeurosis, or Recto-vesical Fascia. 
 
 Dissection. — This aponeurosis must be studied both from the cavity of the pelvis and 
 from the perineum. It is exposed in the pelvis by removing the peritoneum, and the 
 loose cellular tissue beneath that membrane : this should be done without any cutting 
 instiument. To view this fascia from the perineum, it is necessary to take away the 
 adipose tissue that occupies the perineal fossae, and also the levator ani muscle. 
 
 The superior pelvic aponeurosis forms a complete floor for the pelvis. Anteriorly it is 
 remarkable for its strength and shortness ; in fact, it does not reach the inlet in this sit- 
 uation, but arises on each side from the symphysis pubis, presenting the appearance of 
 bands or columns, which are more or less separated from each other, and become at- 
 tached to the front of the neck of the bladder, whence the name of anterior ligament of 
 the bladder, which the older anatomists gave to this part of the aponeurosis. More exter- 
 nally, it forms a strong arch (the sub-pubic arch), which completes the posterior orifice of 
 the obturator or sub-pubic canal (i, fig. 48). This arch is not unfrequently double, and 
 then one of the foramina gives passage to vessels, and the other to nerves. 
 
 Still more externally, it is attached to the brim of the pelvis, in the manner I have al- 
 ready pointed out. 
 
 Posteriorly it is extremely thin, passes in front of the sciatic plexus, and is lost upon 
 the sacrum. Sometimes it appears to be divided into two lamina, the posterior of which 
 passes in front of the sciatic plexus, and the anterior in front of the internal ihac vessels, 
 to which it would seem to furnish sheaths. 
 
 Relations. — Its upper surface is concave, and connected with the peritoneum by loose 
 cellular tissue, containing more or less fat. Its lower surface is convex, and covered by 
 the levator ani : it forms part of the great perineal excavation, and is in relation with 
 the pjTiformis and obturator intemus mucles, with the sacral plexus, &c. 
 
 This aponeurosis is perforated by a great number of openings : in the male it is pierced 
 by the prostate {i,fiff. 181) and the bladder (h), on the sides of which it is prolonged, and 
 reflected on to the rectum, whence the name of the recto-vesical aponeurosis, given to it by 
 M. Carcassone. In the female it is also perforated by the vagina. On each side of the 
 bladder and prostate it is strengthened by two tendinous bands, which run from before 
 backward. These are sometimes very strong ; they extend from the symphysis pubis 
 (6) to the spine of the ischium (e), pass along the bladder and the prostate, and are re- 
 flected upon their sides. 
 
 In front, it has some openings for the vesical and prostatic vessels. 
 
 Behind it presents a considerable opening, which corresponds to the outlet of the pel- 
 vis, and gives passage to the lumbo-sacral nerve and the gluteal vessels. The extrem- 
 ity of the arch formed by it corresponds to the anterior border of the sciatic notch. It 
 is through this opening that sciatic herniae protrude. 
 
 We not uncommonly find larger or smaller openings in this fascia, of an oblong or cir- 
 cular shape, leading into conical culs-de-sac, which are filled with fat. Lastly, it is per- 
 forated behind by the ischiatic and internal pudic vessels. It does not appear to be in- 
 tended for the passage of the vessels which are distributed in the interior of the pelvis, 
 for it seems to invest these in fibrous sheaths. 
 
 Uses. — The superior pelvic aponeurosis forms the floor of the pelvis ; it is pushed 
 downward by the action of the diaphragm and abdominal muscles, and tends to prevent 
 the occurrence of perineal herniae, which otherwise would be extremely common : it 
 forms a boundary between the sub-peritoneal and the perineal cellular tissue, and also 
 limits the progress of inflammation and infiltrations. Infiltration of urine above the fas- 
 cia can only be caused by rupture of the bladder itself The prostate {i,fig. 181) is al- 
 most entirely below the fascia, and therefore, in the lateral operation for stone, in which 
 this gland is the principal structure to be divided, inflammation and infiltration of the 
 cellular tissue are extremely rare. When they do occur, the section or laceration must 
 have been prolonged into the body of the bladder. 
 
 The Lateral Pelvic Aponeurosis, or Fascia of the Obturator Muscle. 
 
 Dissection. — ^This aponeurosis is more advantageously studied, at least in its most impor- 
 tant part, from the perineum, than from the cavity of the pelvis : it is exposed on either 
 side by removing the adipose tissue, which fills up the perineal fossa. This aponeurosis, 
 which is quite distinct from the obturator ligament, commences at the upper part of the 
 circumference of the obturator foramen, and at the brim of the pelvis, in connexion with 
 
THE FEMORAL APONEUROSIS. 30P 
 
 the superior pelvic aponeurosis, which it soon leaves, and is applied to the obturator in- 
 temus muscle : it then unites below with the reflected portion of the great sacro-sciatic 
 ligament, and is prolonged upon that portion of the anterior surface of the glutaeus max- 
 imus which projects beyond the ligament, and also upon the coccygeus muscle. 
 
 Relations. — On the inner side and above, it is only separated from the superior pelvic 
 aponeurosis by the levator ani, which is applied to that aponeurosis ; lower down, the 
 two aponeuroses are separated by a considerable interval, which is occupied by fat : this 
 interval forms the perineal fossa. On the outside it is in contact with the obturator in- 
 ternus, and lower down with the internal pudic vessels and nerves. 
 
 Uses. — It binds down the obturator internus muscle, and protects the internal pudic 
 vessels and nerves, which are, therefore, rarely cut in operations in the perineum. It 
 forms the external boundary of the perineal fossa. 
 
 TTie Perineal Fosscb. — Situated between the superior pelvic aponeurosis (which is lined 
 below by the levator ani) and the lateral pelvic aponeurosis, there is found on each side 
 of the anus a conical space, the base of which is directed downward, and corresponds 
 to the skin : it is formed behind by the lower border of the glutaeus maximus ; in front, 
 by the transversus perinei muscle ; on the inside, by the levator ani and the superior pel- 
 vic aponeurosis ; and on the outside, by the tuberosity of the ischium.* Each of these 
 fossae is filled by a large quantity of fat, and traversed by fibrous laminae, some of which 
 extend vertically from the apex to the base, and divide the contained adipose ceUular 
 tissue into several distinct portions. When an abscess occurs in either of these fossae, 
 it may be easily conceived how difficult it is for the inner surface of its parietes to come 
 into opposition : hence the pathology of fistulae, and the modes of cure which are adopted. 
 
 The Aponeuroses of the Lower Extremity. 
 The aponeuroses of the lower extremity comprise the femoral fascia ; the fascia of the 
 leg ; the annular ligaments, which bind down the tendons of the muscles of the leg, as 
 they are passing upon the dorsal or plantar surface of the foot ; the plantar and dorsal 
 fascia of the foot ; and, lastly, the fibrous sheaths, which maintain the tendons in con- 
 tact with the phalanges of the toes. We shall describe these in succession. 
 
 The Femoral Aponeurosis, or Fascia Lata. 
 
 After the remarks which we have already made upon the aponeuroses generally, it 
 may be easily conceived that the muscles of the thigh, which are so numerous, of such 
 great length, and so loOsely united together, and almost all of which are reflected to a 
 greater or less amount over the knee, require to be kept in close contact with each oth- 
 er and with the bones ; hence the necessity for the femoral' aponeurosis, consisting of a 
 large fibrous sheath, that confines without compressing the muscles, and the strength of 
 which is directly proportioned to the force of the muscles, and their tendency to dis- 
 placement. Its superficial or sub-cutaneous surface {g h,fig. 137) is separated from the 
 skin by a very thin fibrous layer, the fascia superficialis (not shown in fig. 137), which 
 can be more easily demonstrated immediately below the femoral arch, and along the sa- 
 phenous vein. Between the femoral aponeurosis or fascia lata and this superficial fas- 
 cia, which results from the union of the fibrous prolongations given off by the deep sur- 
 face of the skin, the sub-cutaneous vessels and nerves take their course, and communi- 
 cate with the deep vessels and nerves, either by simple openings or by fibrous canals, of 
 variable length. Under this fascia, also, are situated the superficial lymphatic vessels 
 and glands of the groin. 
 
 A great number of the superficial nerves of the thigh have special sheaths, which are 
 hollowed out, as it were, in the substance of this aponeurosis. 
 
 The femoral aponeurosis is perforated with a great number of foramina opposite the 
 femoral vessels, from Poupart's ligament to the entrance of the vena saphena {x) into 
 the femoral vein (y). These foramina, which occupy a triangular space, of which the 
 base is above and the apex below, are intended for the ' passage of a great number of 
 lymphatic vessels, which pass through it to join the deep set. This has been called the 
 sieve-like portion of the fascia lata, or the fascia cribriformis (v) : it has been said by some, 
 that the aponeurosis is altogether wanting in this situation.! We not unfrequently find 
 a lymphatic gland occupying one of the foramina. 
 
 * [These spaces are the ischio-recial fossie of Velpeau ; they are described by him as if lined by an aponeu- 
 rosis (the ischio-rectal) composed of two layers, one external or ischiatic, corresponding to the lateral pelvic 
 aponeurosis of M. Cruveilhier, and another internal or rectal, which covers the lower surface of the levator 
 ani from the coccyx to the posterior border of the transversus perinei, and unites with the other layer before, 
 above, and behind. This latter layer is very thin, and continuous with the united margins of the superficial 
 perineal fascia and the triangular ligament, behind the transverse muscle, and is alluded to by M. Cruveilhier 
 (p. 307) as a reflection of the superficial fascia. 1 
 
 t [And then the cribriform fascia is regarded, not as belonging to the fascia lata, but as formed by a deep 
 layer of the superficial fascia, situated beneath the sub-cutaneous vessels, adherent to the borders of the saphe- 
 nous opening in the fascia lata, and perforated by those vessels. The saphenous opening is, according to this 
 view, not the foramen (t) through which that vein passes, but the aperture (n) left between the iliac (g) and 
 pubic (A) portions of the fascia lata, and is bounded externally by the crescentic margin of the iliac portion 
 or the falciform process of Bums (see the left side of Jiff. 137, where the cribriform fascia has been enlirelj 
 removed).] 
 
310 APONEUROLOGY. 
 
 The most remarkable of all these openings is undoubtedly that (i) for the vena saphena 
 interna, where that vessel enters the femoral vein, at the upper part of the thigh, eight 
 or ten lines below Poupart's ligament. The margin of this opening, which has been 
 improperly called the inferior orifice of the crural canal, can only be demonstrated in its low- 
 er half, on account of the almost complete absence of the aponeurosis above it : this is 
 the reason of the semilunar form of the portion of the fascia over which the vein passes. 
 
 The deep surface of the fascia lata gives off a great number of prolongations, which 
 pass between the muscles, and form their proper investments or sheaths. 
 
 The largest of these prolongations form two lateral septa, called the inter-muscular sep- 
 ta, which extend from the fascia to the linea aspera ; each has the form of a triangle, 
 having its base directed downward and its apex upward ; they are extremely thick, es- 
 pecially below. 
 
 The Inter-muscular Septa of the Femoral Aponeurosis. 
 
 Of these there are two, one internal and the other external. 
 
 The Internal Inter-muscular Septum. — This serves at once as a septum, an aponeurosis 
 of insertion, and a sheath for the vastus intemus : it extends from the anterior inter- 
 trochanteric line to the inner condyle of the femur. 
 
 Its anterior surface affords attachments to the vastus intemus throughout its whole 
 extent : its posterior surface is in opposition with the adductors, and is intimately uni- 
 ted to their aponeuroses. Its outer margin is attached to the Unea aspera : its inner 
 margin is very thick, and prominent below, where it is strengthened by the inferior ten- 
 don of the adductor magnus, and may be felt under the skin like a cord. It appears to 
 become continuous below with the internal later£il ligament of the knee. 
 
 It is composed of very strong vertical fasciculi, passing somewhat obliquely down- 
 ward and inward. These fasciculi are bound together above the inner condyle by oth- 
 ers passing transversely, and are crossed almost at right angles by the tendinous fibres 
 of the adductors. 
 
 Lastly, the internal septimi is perforated, near the linea aspera, by a number of orifices 
 destined for the passage of vessels, and forming communications between the anterior 
 and the internal sheath of the muscles of the thigh. 
 
 The External Inter-muscular Septum. — This serves as a septum, an aponeurosis of in 
 sertion, and as a sheath for the vastus extemus. 
 
 It extends from the great trochanter to the external condyle, above which it forms a 
 projecting cord : it affords attachments to the vastus extemus in front, and to the short 
 head of the biceps behind. . Its inner margin is attached to the linea aspera : its outer 
 margin forms a prominent cord, especially below. 
 
 It consists of fibres directed vertically, or somewhat obliquely outward, and strength- 
 ened by transverse fibres above the condyle. Like the internal septum, it is perforated, 
 especially above and below : above, for the passage of the circumflex vessels ; below, 
 for the passage of the articular vessels of the knee. 
 
 We shall now examine the different sheaths fiirnished by the femoral aponeurosis. 
 One of the most important of these is, as it were, hollowed out of the sides of the others, 
 and belongs to the femoral vessels. 
 
 The Sheath of the Femoral Vessels. 
 
 The femoral artery (z,fig. 137) and vein (y) are enclosed in a prismatic and triangular 
 tendinous canal, which protects them in their course amid the muscles of the thigh. 
 The portion of the canal (laid open in fig. 137) included between the femoral arch and 
 the point where the vena saphena opens into the femoral vein, has received the name 
 of the crural canal, a term to which I have always objected, since it was first introduced 
 into anatomical nomenclature, because it establishes a false analogy between the ingui- 
 nal canal and this upper portion of the sheath of the femoral vessels ; for, while an 
 oblique inguinal hernia traverses the entire length of the inguinal canal, crural herniae, 
 as far, at least, as my own observation extends, never protrude through the saphenous 
 opening, but escape inunediately below the femoral arch, and lift up the cribriform por- 
 tion of the fascia lata.* 
 
 The anterior wall of the sheath of the femoral vessels is formed above by the cribri- 
 form portion of the femoral fascia (g',fig. 137), then by the fascia itself, and, lastly, by 
 the posterior layer of the sheath of the sartorius, in which place it is thin and transparent. 
 
 Tlie internal wall is formed above by the very strong layer covering the pectineus ; be- 
 low, by the weaker layer investing the adductors. 
 
 The external wall consists of the very strong sheath {s',fig: 136) of the psoas and ilia- 
 cus : externally to this wall is situated the crural nerve, a branch of which perforates 
 
 * [The tenn "crural ring" is, in this country, commonly limited to the space (r,fig. 136) situated internal- 
 ly to the femoral vein. By the term " crural canal" is generally understood that portion only of the canal de- 
 scribed by M. Cruveilhier as the " craral canal," which is situated on the inner side of the femoral vein, and 
 is occupied by cellular tissue, lymphatic vessels, and sometimes by a lymphatic gland. If the term crural ca- 
 nal be thus defined, if the cribriform fascia be regarded as a part of the superficial fascia, and the saphenous 
 aperture as the space between the iliac and pubic portions of the fascia lata (see note, p. 309), the analogy be- 
 tween the crural and inguinal canals will not be so very remote.] 
 
THE FEMORAL APONEUROSIS. 81 J 
 
 the sheath and joins the vessels. Lower down, the external wall is formed by the apo 
 neurosis of the vastus internus. 
 
 The three great Muscular Sheaths of the Femoral Aponeurosis. 
 
 By means of the internal and external inter-muscular septa, the muscles of the ante- 
 rior region of the thigh are separated from those of the posterior and internal regions ; 
 a weaker septum than the preceding intervenes between the muscles of the internal 
 and posterior regions. It foUows, then, that the femoral aponeurosis presents three 
 great tendinous sheaths : an anterior, an internal, and a posterior. 
 
 The great posterior sheath is undivided : it is common to the biceps, the semi-tendino- 
 sus, and the semi-membranosus. 
 
 The great anterior and internal sheaths are subdivided into a number of secondary 
 uheaths, in most cases corresponding with the number of the muscles. 
 
 The great Anterior Sheath. — The sartorius has a proper sheath, remarkable for its pris- 
 matic and triangular form. The rectus femoris, or long head of the triceps, is separated 
 from the two vasti by a tendinous layer, very thin below, but strong above, and com- 
 posed of vertical fibres. 
 
 The tensor vaginae femoris is contained in the strongest sheath in the human body, 
 for it is formed by the fascia lata itself The deep layer of this sheath is much thinner 
 than the superficial ; it commences at the anterior inferior spinous process of the ilium, 
 below the rectus, and may be regarded eis the deep origin of the ^road band in which 
 the tensor vaginae femoris terminates : it is composed of verticed fibres, prolonged be- 
 tween the rectus and the vastus externus. Lastly, above and on the outside, we find 
 the sheath of the psoas and iliacus {s',fig. 136), which forms a continuation of the lum- 
 bo-iliac aponeurosis, or fascia iliaca. 
 
 The great internal sheath furnishes a number of tendinous lamellae, which separate the 
 different muscles of this region. Thus, there is a proper sheath for the gracilis, a com- 
 mon one for the pectineus and the adductor longus, one for the adductor brevis, and an- 
 other for the adductor magnus. The sheath of the obturator externus is continuous 
 with that of the adductor brevis ; it commences by a very strong fibrous lamina or arch, 
 which arises from the anterior edge of the pubes, and is directed obhquely outward to 
 the fibrous capsule of the hip-joint. This arch conceals the anterior orifice of the obtu- 
 rator canal, and protects the obturator vessels and nerves. 
 
 Lastly, the two vasti, which extend into all the regions of the thigh, have sheaths 
 formed by the femoral fascia, where they are superficial, and by the internal and exter- 
 nal inter-muscular septa, and the posterior laminae of the other sheaths in their more 
 deeply-situated portions. 
 
 In the midst of the sheaths of the anterior and internal regions we find the sheath of 
 the femoral vessels already described. 
 
 The Superior Circumference of the Femxiral Aponeurosis. 
 
 In front the femoral aponeurosis arises from the femoral arch, with which it is so pei- 
 fectly continuous as to render the arch tense : hence the plan, already mentioned as 
 proposed by Scarpa, of endeavouring to remove the constriction in cases of strangulated 
 crural hernia, by puncturing the femoral aponeurosis. 
 
 But the mode of origin and continuity of this fascia with the femoral arch is not the 
 same on the inner and outer sides. On the outside, the iliac portion of the femoral apo 
 neurosis (g, fig. 137) arises by a single very thick layer ; more internally, in the situation 
 of the femoral vessels, it arises by two layers, one superficial, thin, and perforated by 
 foramina (the cribriform portion, v) ; the other deep, called its pubic portion (A), which is 
 continuous with the fascia iUaca (s,fig. 136), covers the pectineus, and sends off a pro- 
 longation between that muscle and the psoas. This deep layer forms the posterior wall 
 of the canal of the femoral vessels. 
 
 On the inside of the thigh, the femoral aponeurosis arises from the body of the os pu- 
 bis and the ascending ramus of the ischium. 
 
 On the outside and behind, it arises from the crest of the ilium by very numerous ver- 
 tical fibres, which are strengthened, especially behind, by other horizontal fibres. Be- 
 tween the posterior superior spine of the ilium and the crest of the sacrum there is a 
 tendinous arch, which is common to the femoral fascia and the aponeurosis of the long 
 muscles of the back. 
 
 The Glutceal Aponeurosis. 
 The glutaeal aponeurosis forms the upper and back part of the femoral fascia. It cov- 
 ers the glutaeus medius, in which situation it is extremely thick, and is continuous with 
 the broad band of the tensor vaginae femoris. Having reached the upper border of the 
 glutaeus maximus, it is divided into two layers : one superficial and very thin, which 
 covers the outer surface of the gluta;us maximus, becomes thinner below, and continu- 
 ous with the femoral fascia ; the other deep and thicker, especially above and behind, 
 where it affords attachment to the glutaeus maximus, and is blended with the great sa- 
 cro-sciatic ligament. It becomes ver}' thin whe: e it separates the gluta3us maxirau? 
 
312 APONEUROLOGY. 
 
 from the deep-seated muscles. A synovial capsule intervenes between this fascia and 
 the great trochanter, and another between it and the tuberosity of the ischium. 
 
 It presents a very remarkable opening called the glutaal arch, for the passage of the 
 glutseal vessels and nerves. Lastly, over that portion of the glutaeus maximus which 
 enters into the formation of the corresponding perineal fossa, it acquires a great degree 
 of thickness, and, at the lower border of the muscle, is blended with the superficial layer 
 of the gluteal fascia. 
 
 The Inferior Circumference of the Femoral Aponeurosis. 
 
 The femoral aponeurosis terminates below, around the knee-joint, where it becomes 
 continuous, partly with the fascia of the leg, and partly with the fibrous structures cov- 
 ering this articulation. Concerning the arrangement of these fibrous laminae we shall 
 offer a few remarks. 
 
 Behind, the femoral aponeurosis passes over the popliteal space, and is continuous 
 with the fascia of the leg. 
 
 In front, it is prolonged over the patella, from which it is separated by a synovial bur- 
 sa; it is very thin, and is continued in front of the ligament of the patella, upon which 
 it forms a thin layer of transverse fibres. 
 
 071 the inside, it is at first blended with the sheath of the sartorius, and then with the 
 horizontal portion of the tendon of this muscle ; it crosses the fibres of that portion per- 
 pendicularly, and becomes continuous with the fascia of the leg. 
 
 Under this layer of fibrous tissue we find, on the inside of the knee, another very dense 
 layer, formed by vertical tendinous fibres derived from the vastus internus, and inserted 
 into the upper part of the inner surface of the tibia, beneath the tendon of the sartorius. 
 This fibrous layer, which may be regarded as the lower or tibial insertion of the vastus 
 extemus, occupies the interval between the internal lateral ligament of the knee-joint 
 and the patella. Its vertical fibres are crossed by others at right angles, extending from 
 tne internal tuberosity of the femur to the corresponding margin of the patella. 
 
 Lastly, under this we find another very thin layer, belonging to the synovial capsule. 
 
 On the outside, the femoral aponeurosis is blended with the broad band of the tensor 
 vaginae femoris, from which it can be distinguished only by the horizontal direction of 
 its fibres. 
 
 Beneath this very thick layer we find a thin one, composed of fibres stretching from 
 the external tuberosity of the femur to the patella ; and, lastly, another thin layer be- 
 longing to the synovial membrane. 
 
 Structure of the Femoral Aponeurosis. 
 
 It is thin behind and on the inside, thicker in front, and extremely thick on the out- 
 side of the thigh, where, indeed, it may be said to exceed all other fibrous membranes in 
 thickness and in strength. This thickened portion is bounded in front by a line extend- 
 ing vertically downward from the anterior superior spinous process of the ilium. Its lim- 
 its behind are no less distinctly defined ; hence the name given to it of the broad hand 
 {fascia lata). 
 
 This great density is owing to some very strong vertical fibres, arising from the front 
 of the crest of the ilium. It is connected with the great force and tendency to displace- 
 ment of the vastus externus. 
 
 We may add, that the femoral aponeurosis is composed of horizontal fibres, sometimes 
 regularly parallel, as in its thinnest portions, and sometimes intersecting each other. 
 These horizontal fibres are even seen opposite the broad band on the outer side, from 
 which they are distinguished by their direction. 
 
 There is a very beautiful preparation of this aponeurosis in the Museum of the Facul- 
 ty of Medicine : similar preparations should be made by those who wish to obtain a good 
 idea of the tendinous sheaths, and the shape of the muscles of the thigh. It is to be 
 made by removing all the muscles from their sheaths by means of longitudinal incisions, 
 and substituting for them a quantity of tow, which must be taken out when the aponeu- 
 roses are completely dried. The form of the sheaths exactly represents that of the cor- 
 responding muscles. A tolerably accurate idea of these sheaths may also be obtained 
 by cutting across each sheath and the muscle which it contains, in a fresh subject. The 
 circumference of the section of the portion of the sheath that becomes visible after the 
 retraction of the muscle will give an excellent idea of the figure of the different sheaths, 
 which are all angular and polyhedral like the muscles, but never rounded : during health 
 they are completely filled by the muscles, which in emaciated persons, on the contrary, 
 do not occupy more than a half, a third, or a sixth of the area of their sheaths. 
 
 Such is the femoral fascia. Its tensor muscles consist of the tensor vaginae femoris and 
 the glutaeus maximus, the tendon of which is received between two layers of this fascia. 
 
 Aponeuroses of the Leg and Foot. 
 Aponeurosis of the Leg. 
 The aponeurosis of the leg forms a strong general investment for the whole leg, except- 
 
ANNULAR LIGAMENTS OF THE TARSUS. 313 
 
 mg the internal surface of the tibia, which is covered by it only at its lower part, a little 
 above the malleoli. 
 
 Its external surface is separated from the skin by the superficial vessels and nerves, 
 several of which perforate it, either directly, or after having run for a short distance in its 
 substance. The external saphenous vein and nerve receive from it a complete sheath. 
 
 Its internal surface covers all the muscles of the leg, and does not adhere to them ex- 
 cepting above and in front, where it gives attachment to the tibialis anticus and the ex- 
 tensor communis digitorum. From the internal surface there proceeds on the outer side 
 of the leg two principal tendinous septa, one situated between the muscles of the ante- 
 rior tibial region and the peronei, the otlier between the peronei and the muscles of the 
 posterior region of the leg. There are, therefore, three principal sheaths in the leg, an 
 anterior, an internal, and a posterior. The latter is subdivided into two other sheaths 
 by a very strong transverse lamina, becoming still stronger below, which separates the 
 muscles of the deep posterior layer and the posterior tibial and peroneal vessels and 
 nerves from the superficial layer of muscles, or the triceps suralis. Lastly, some tendi- 
 nous laminae, more or less complete, are interposed between the different muscles of 
 each region. Thus, a tendinous layer separates the tibialis anticus, at first from the ex- 
 tensor communis digitorum, and then from the extensor proprius pollicis : this layer dis- 
 appears in the middle of the leg. Another very strong tendinous lamina separates the 
 tibialis posticus from the flexor longus digitorum on the one hand, and from the flexor 
 longus pollicis on the other. 
 
 Superior Circumference. — If we now examine the manner in which the aponeurosis 
 of the leg becomes continuous with that of the thigh, we shall find that, posteriorly, the 
 femoral fascia is prolonged directly upon the leg, in order to form the posterior part 
 of its aponeurosis, which, in this situation, also receives an expansion from the ten- 
 dons of the biceps, sartorius, gracilis, and semi-tendinosus, and from the broad band of 
 the fascia of the thigh. Anteriorly the fascia of the leg is continous with that of the 
 thigh over the patella, and appears also to arise directly from the outer edge of the ante- 
 rior tuberosity of the tibia, from the head of the fibula, and from the tendon of the biceps, 
 which, as we have already seen, gives off an aponeurotic expansion backward. 
 
 By its lower circumference this fascia is continuous with the annular ligaments of the 
 ankle, which we shall presently describe. 
 
 Structure. — On examining the direction of the fibres and the thickness of the fascia of 
 the leg, it is found that it is much thicker in front than on the outer side of the leg, and 
 still more so than behind ; that, in the first situation, in the ujpper three fourths of its ex- 
 tent, it is composed of obliquely interlaced fibres, some of which descend from the spine 
 of the tibia, and others from the anterior angular surface of the fibula ; and that in the 
 lower fourth of the anterior region of the leg, and in the whole extent of the posterior re- 
 gion, it is composed of circular fibres. 
 
 At the point where the muscles of the leg become tendinous, and are reflected over 
 the ankle, they require very strong sheaths to keep them in contact with the joint ; the 
 fascia of the leg, therefore, forms, opposite this part, the anterior, internal, and external 
 annular ligaments. 
 
 The Annular Ligaments of the Tarsus. 
 
 The annular ligaments of the tarsus are three in number : an anterior or dorsal, an in- 
 ternal, and an external. 
 
 The dorsal annular ligament of the tarsus. The aponeurosis of the leg is thicker at the 
 lower and anterior part of the leg, and binds down the corresponding portion of the mus- 
 cles in that region. But there is, in addition to this, a dorsal annular ligament of the 
 tarsus (see fig. 128), which arises, by a narrow but thick extremity, in front of the as- 
 tragalo-calcanean fossa, becomes broader as it extends inward, and is divided into two 
 bands. The superior band passes upward and inward above the internal malleolus, and 
 is split into two layers, in such a way as to form two complete sheaths : one internal, 
 for the tibialis anticus ; the other external, for the extensor longus digitorum and the 
 peroneus tertius. Between these two complete sheaths, which are separated from the 
 synovial capsule of the joint by a layer of cellular tissue, we find an incomplete sheath 
 (for the annular ligament is not split into two layers in this situation), intended for the 
 extensor proprius pollicis and the anterior tibial vessels and nerves : the internal sheath is 
 the higher, and situated opposite the lower extremity of the tibia ; the external sheath 
 is lower, and corresponds to the ankle-joint. The inferior band, or the lower bifurcation 
 of the annular ligament, passes forward and inward to the front of the tarsus, and be- 
 comes continuous with the internal plantar aponeurosis. This lower band forms a sec- 
 ond annular ligament, which furnishes to each of the three preceding muscles, upon the 
 dorsum of the foot, a less powerful sheath than that afforded by the upper band : it keeps 
 the tendons closely applied to the bones. 
 
 The external and internal annular ligaments of the tarsus are two fibrous bands, contin- 
 uous with the fascia of the leg on the one hand, and with the plantar aponeurosis on the 
 other. 
 
 Rr 
 
i 
 
 314 APONEUROLOGY. 
 
 The internal annular ugament arises from the borders and summit of the internal mal- 
 leolus, and proceeds in a radiating manner to the inner side of the os calcis, and the in- 
 ner margin of the internal plantar aponeurosis. Beneath this sheath, which is thick- 
 er below than above, and closes in the concavity on the inner surface of the os cal- 
 cis, proceed the posterior tibial vessels and nerves, and also the tendons of the tibialis 
 posticus, the flexor longus digitorum, and the flexor longus poUicis. For these several 
 parts there are four very distinct sheaths : the most superficial is that for the vessels 
 and the nerves ; two sheaths, placed one over the other (see Jig. 130), and behind the 
 internal malleolus, belong, the anterior to the tibialis posticus (w), and the posterior or 
 more superficial to the flexor longus digitorum (o). These two sheaths soon separate 
 as the two tendons diverge from each other towards their insertions : as the sheath of 
 the tibialis posticus is continued as far as the insertion of that muscle, the sheath of the 
 flexor longus digitorum accompanies it to where it gets beneath {i. e., deeper from the 
 surface than) the plantar fascia. The sheath of the flexor longus pollicis {p) is lower 
 than the preceding, and extends obliquely along the astragalus and os calcis, to be cov- 
 ered by the internal plantar fascia. 
 
 The external annular ligament forms a common sheath for the two peronei, longus et 
 brevis : it extends from the border of the external malleolus to the os calcis, and is 
 completed on the inside by the external lateral ligaments. It is at first single, but soon 
 becomes subdivided into two other sheaths, one of which is destined for the tendon of 
 the peroneus brevis, and the other for that of the peroneus longus. 
 
 The Aponeuroses of the Foot. 
 
 These are divided into the dorsal and plantar. 
 
 The Dorsal Aponeuroses of the Foot. 
 
 These comprise the dorsal aponeurosis, properly so called, the pedal aponeurosis (Vapo- 
 neurose pidieuse), and the dorsal interosseous aponeuroses. 
 
 Dorsal Aponeurosis of the Foot. — While the upper margin of the annular ligament is 
 blended with the fascia of the leg, which appears to be inserted upon it, the anterior 
 margin of the same ligament becomes continuous with the dorsal aponeurosis of the foot. 
 This dorsal aponeurosis is a thin layer, which forms a general sheath for all the tendons 
 situated upon the dorsum of the foot : it gradually disappears in front, opposite the an- 
 terior extremities of the metatarsal bones, and is attached at the sides to the borders 
 of the foot, becoming continuous with the plantar fascia. These tendons, again, are sep- 
 arated from the extensor brevis digitorum by another and still thinner layer, which in- 
 vests that muscle : this is the pedal aponeurosis ; lastly, upon the same surface of the 
 foot we find the four dorsal interosseous aponeuroses, viz., one for each interosseous space. 
 The Plantar Aponeuroses. 
 
 The plantar aponeuroses or fasciae are three in number : one middle, the other two 
 lateral. 
 
 The middle plantar aponeurosis is very strong, is attached to the inner of the posterior 
 tubercles of the calcaneum, becomes suddenly contracted, and afterward gradually ex- 
 pands without diminishing perceptibly in thickness. Opposite the anterior extremities 
 of the metatarsal bones, it divides into four bands, which are themselves bifurcated al- 
 most immediately, so as to embrace the flexor tendons of the four outer toes. Becom- 
 ing moulded on the sides of these tendons, they furnish those of each toe with an almost 
 complete sheath, which is attached to the upper and lateral borders of the anterior gle- 
 noid ligament of the corresponding metatarso-phalangal articulation, and becomes con- 
 tinuous with the tendinous sheath of the corresponding toe. These four sheaths are 
 separated by three arched openings, through which proceed the lumbricales and interos- 
 seous muscles, and the plantar vessels and nerves. There is a perfect analogy between 
 the middle plantar and the middle palmar aponeurosis ; but the former is by far the 
 stronger. It constitutes, indeed, a true ligament for the foot, offers a powerful resist- 
 ance to the forced extension of the phalanges upon the bones of the metatarsus, and sup- 
 ports the antero-posterior arch of the sole of the foot. I have known exceedingly vio- 
 lent pain to be produced by distension, and, probably, laceration of some of the fibres of 
 this aponeurosis. The margins of the middle plantar aponeurosis are curved upward, 
 so as to embrace the flexor brevis digitorum on each side ; they become continuous 
 with the external and internal plantar aponeuroses, and form septa between the muscles 
 of the middle and those of the external and internal plantar regions : in front these septa 
 are complete, but only partial behind. The upper surface of this fascia gives attach- 
 ment, posteriorly, to the short flexor of the toes : the proper tendinous expansion of this 
 muscle appears to be given otf from the upper surface of the plantar aponeurosis. 
 
 Some transverse fibres strengthen this fascia in front, and I shall also notice some 
 other transverse fibres, perfectly distinct from the preceding, which form a true trans- 
 verse ligament for the four outer toes : it is situated opposite the middle of the lower 
 surface of the first phalanges, and is admirably adapted for opposing their dislocation. 
 
 The External and Internal Plantar Aponeuroses. — The external plantar aponeurosis, very 
 
THE APONEUROSES OF THE SHOULDER. 315 
 
 thick behind and thin in front, gives attachment by its upper surface to the abductor 
 muscle of the Httle toe, and is bifurcated at the posterior extremity of the fifth metatar- 
 sal bone. The external division of this bifurcation is very strong, is inserted into the 
 enlarged posterior extremity of the fifth metatarsfd bone, and may be regarded as a pow- 
 erful medium of connexion between that bone and the cuboid. The internal plantar apo- 
 neurosis is thin in comparison with the external ; it commences behind by an arch, ex- 
 tending from the inner malleolus to the os calcis ; its inner margin is attached to the 
 corresponding border of the tarsus, and is continuous with the dorsal annular ligament 
 and with the dorsal fascia of the foot ; its outer margin is blended with the middle plan- 
 tar fascia, or, rather, is reflected upward, to complete the sheath for the internal mus- 
 cles of the foot. 
 
 These three plantar fasciae just described form three sheaths, which are quite distinct 
 in their anterior five sixths, but communicate with each other behind. 
 
 The internal plantar sheath includes the abductor and the short flexor* of the great 
 toe, which are separated from each other by a layer of fibrous tissue ; it also contains 
 the internal plantar artery and nerves. 
 
 The external plantar sheath includes the abductor and the flexor of the little toe, Avhich 
 are also separated by a tendinous layer. Lastly, the middle plantar sheath includes the 
 short flexor of the toes, the tendon of the flexor longus digitorum, the flexor accesso- 
 rius, the lumbricales, the tendon of the flexor longus poUicis, the oblique adductor,! the 
 transversus pedis, and the external plantar vessels and nerves. The sheath of the 
 flexor brevis digitorum is completed above by an aponeurotic layer, which separates it 
 from the tendons of the long flexor and from the accessorius. A prope\' sheath exists 
 for the oblique adductor,+ and a subdivision of the same sheath for the transverse ad- 
 ductor. It is formed above by the interosseous aponeuroses, and below by a thin layer 
 attached to the circumference of the deep hollow in which the adductors are lodged. 
 Lastly, the inferior interosseous aponeurosis is remarkable for its thickness, and for the 
 septa which it gives off between the interosseous muscles. 
 
 The sheaths into which the flexor tendons of the toes are received opposite the pha- 
 langes resemble so exactly those of the fingers, that I shaU not anticipate what will be 
 said hereafter regarding the latter. We find the same system of synovial membranes, 
 and the same loose, membranous, and extensible cellular tissue for the flexor tendons 
 of the toes as for those of the fingers. In all sheaths that are partly osseous and partly 
 tendinous, we find a synovial membrane ;t but, on the other hand, there is nothing more 
 than a loose cellular tissue in situations where a tendon or muscle ghdes in the interior 
 of a confining aponeurosis. 
 
 The Aponeuroses of the Upper Extremity. 
 
 Tliese comprise the aponeuroses of the shoulder ; the brachial aponeurosis ; the apo- 
 neurosis of the forearm ; the dorsal and anterior annular ligaments of the carpus ; the 
 palmar aponeurosis ; and, lastly, the sheaths for the tendons of the flexor muscles of the 
 fingers. 
 
 The Aponeuroses of the Shoulder. 
 
 These are the supraspinous, the infror spinous, the sub-scapular, and the deltoid aponeu- 
 roses. 
 
 The supraspinous aponeurosis is a thick layer of fibrous tissue, attached to the entire 
 circumference of the supra-spinous fossa, and converting it into a sort of osteo-fibrous 
 case, that serves as a sheath for the supra-spinatus muscle, to which it also affords sev- 
 eral points of attachment. This tendinous layer is gradually lost, externally, under the 
 acromio-coracoid arch. 
 
 The infra-spinous aponeurosis is an equally dense and strong fibrous lamina, attached 
 to the entire margin of the infra-spinous fossa, and completing the osteo-fibrous sheath 
 of the infra-spinatus muscle : it is continuous on the outside with the brachial fascia, and 
 gives off from its anterior surface a thick septum intervening between the scapular at- 
 tachments of the teres major and those of the teres minor, and also some thinner septa 
 interposed between the teres minor and the infra-spinatus, and between the different 
 portions of the infra-spinatus muscle itself 
 
 The deltoid aponeurosis. The infra-spinous aponeurosis having reached the posterior 
 border of the deltoid muscle, splits into two layers : of these, the superficial layer invests 
 the deltoid, and terminates in the brachial aponeurosis ; the deep layer continues to cover 
 the tendon of the infra-spinatus, and becomes attached to the tendon of the short head 
 of the biceps. Some very loose cellular tissue, or even a synovial bursa, separates this 
 aponeurosis from the head of the humerus, and the tendons inserted around it. 
 
 The subscapular apo7icurosis is a very thin membrane, which completes the sheath of 
 the sub-scapularis, and gives the muscle some points of attachment. It is fixed to the 
 entire margin of the sub-scapular fossa. 
 
 * [/. e., the inner half of the flexor brevis pollicis of anatomists generally.] 
 t [Including the outer portion of the flexor brevis pollicis of most anatomists.] 
 t See note on ApoNE urology, p. 296. 
 
I 
 
 APONEUROLOGY. 
 
 The Brachial Aponeurosis. 
 
 The brachial aponeurosis commences above at the clavicle, the acromion, and the spine 
 of the scapula, and is continuous with the infra-spinous aponeurosis : on the inner side 
 it arises from the tendons of the pectoralis major and the latissimus dorsi ; and, in the 
 interval between them, from the cellular tissue of the axilla ; it envelops the arm as far 
 down as the elbow, where it becomes continuous with the fascia of the forearm, and is 
 attached to the different bony projections presented by the surface of that joint. Its su- 
 ■perficiaJ, surface is separated from the skin by vessels and nerves, to which it furnishes 
 sheaths of greater or less extent. We may admit the existence of a superficial fascia 
 between the vessels and the skin. 
 
 Its deep surface presents various septa, dividing its interior into a certain number of thin 
 sheaths for the several muscles. It is composed almost entirely of circular fibres, some 
 of which have a somewhat spiral direction : these fibres are intersected at right angles 
 by others passing vertically downward to the fascia of the forearm. 
 
 The brachial aponeurosis is so loose as to permit the free exercise of the muscles con- 
 tained within it, yet sufficiently tense to prevent their displacement. 
 
 It is slightly thickened on either side, along the outer and inner borders of the humerus, 
 and gives off in those situations two very strong inter-muscular septa : one external, the 
 other internal. These septa are in every respect analogous to those of the femoral 
 fascia, and divide the brachial sheath into two great compartments : an interior, contain- 
 ing the muscles on the anterior aspect of the arm, viz., the biceps, the brachialis anti- 
 cus, and the coraco-brachialis, also the upper or brachial portion of the supinator longus, 
 and the extensor carpi radialis longior ; the posterior compartment belongs to the triceps. 
 
 The external inter-muscular septum arises from the anterior border of the bicipital 
 groove, by a narrow and very thick extremity, blended with the posterior margin of the 
 tendon of the deltoid ; it reaches the outer border of the humerus, expands and becomes 
 somewhat thinner, and separates the anterior from the posterior muscles, more espe- 
 cially the triceps from the brachialis anticus, affording attachments to them both. It is 
 perforated very obliquely by the musculo-spiral or radial nerve, and the superior profunda 
 artery, which at first lie behind, but are afterward in front of it. The sheath of this 
 nerve and artery establish a free communication between the anterior and posterior com- 
 partments already alluded to. 
 
 The internal inter-muscular septum, broader and thicker than the preceding, but, like it, 
 of a triangular form, arises from the posterior border of the bicipital groove, below the 
 teres major, is continuous with the tendon of the coraco-brachialis, crossing it at a very 
 acute angle, and becoming partially united to and blended with it, proceeds along and 
 adheres closely to the inner border of the humerus, and terminates at the inner condyle 
 or epitrochlea of that bone. Both of these septa are formed by bands and fibres given 
 off in succession from the corresponding borders of the humerus, and they both afford 
 attachments to the brachialis anticus in front, and to the triceps behind. The ulnar 
 nerve is anterior to the internal septum in the upper part of the arm, but perforates it, 
 and remains in contact with its posterior surface, passing between the attachments ot 
 the triceps. 
 
 From these two great sheaths the proper sheaths of the muscles proceed. First, the 
 deltoid has its proper sheath : another thin aponeurotic layer, gradually becoming thicke? 
 from above downward, consisting almost entirely of vertical fibres, and forming one of 
 the origins of the aponeurosis of the forearm, separates the biceps from the brachialis 
 anticus ; again, the brachial vessels and the median nerve have a special sheath, which 
 also receives at its upper part the basilic vein, and the ulnar and internal cutaneou* 
 nerves ; this is the brachial canal, the counterpart of the femoral canal ; it establishes a 
 communication between the cellular tissue of the axilla, and that in the bend of the 
 elbow ; lastly, a tendinous layer separates the upper half of the long head of the triceps 
 from the other portions of that muscle : the sheath of the coraco-brachialis is given ofl 
 from the inner edge of the biceps. 
 
 We must consider as dependances of the common brachial investment the several 
 sheaths furnished by it to the cephalic, basilic, and median veins, to the branches of the 
 internal cutaneous nerve, and to the superficial ramifications of the musculo-cutaneous 
 nerve. When an artery or a vein previously situated under an aponeurosis becomes 
 sub-cutaneous, the perforation in the aponeurosis is almost always of an arched form. 
 
 The brachial aponeurosis has no muscle analogous to the tensor vaginae femoris ; the 
 pectoralis major and the latissimus dorsi are sufficient to effect its tension. 
 
 The Aponeurosis of the Fokeakm and Hand. 
 
 The Aponeurosis of the Forearm. 
 
 Dissection. — ^Make a circular incision through the skin, immediately above the elbow, 
 
 and from this let two vertical incisions be carried downward to the wrist, one in front 
 
 and the other behind ; let the incisions extend through to the fascia, without dividing it ; 
 
 then cautiously remove the skin, being careful to take Math it the sub-cutaneous adipose 
 
THE APONEUROSIS OF THE FOREARM. 31*3 
 
 tissue ; the superficial veins and nerves may be preserved. The external surface of the 
 fascia may be studied first, and its several sheaths afterward opened in succession. 
 
 The aponeurosis, or fascia of the forearm, ■^orms a general sheath, entirely surrounding 
 or embracing that portion of the upper extremity, with the exception of the posterior 
 border of the ulna. It is semi-transparent, and hence can be seen to be traversed by 
 white lines, generally vertical in their direction, which indicate a corresponding number 
 of thickenings of the sheath, and inter-muscular septa given off from them. 
 
 It is separated from the skin by the superficial veins and nerves ; by its upper part it 
 gives numerous attachments to the subjacent muscles, and this renders the dissection 
 very difficult. By making a vertical incision, however, along the separate sheath which 
 it furnishes to each of the muscles, and then carefully removing the latter, a good idea 
 may be formed of the numerous angular compartments into which the common cavity 
 of the fascia is subdivided. In the first place, it will be seen that this fascia, like all 
 other investing aponeuroses, is composed of proper and superadded fibres ; that the 
 proper fibres are nearly or quite circular, are more or less oblique, and more or less in- 
 terlaced, but the superadded fibres are vertical. It will be found that it is twice as thick 
 upon the dorsal as upon the palmar surface of the forearm ; that its thickness and its 
 strength increase from above dowTiward ; and that it is strengthened by a great number 
 of superadded fasciculi, consisting of aponeurotic expansions from the tendons of the 
 adjacent muscles. Thus, the brachialis anticus on the outside, the biceps on the inside 
 and in front, and the triceps behind, give off tendinous expansions to this aponeurosis : 
 of these the most remarkable is, without doubt, that given off from the biceps, which 
 muscle may be regarded, indeed, as the tensor of the anterior portion of the fascia. 
 This expansion constitutes, in fact, one of the terminations of the biceps, with the ex- 
 ternal fasciculi of which it is continuous, and, moreover, arises from the outer edge and 
 the anterior surface of its tendon. This expansion, so important in consequence of its 
 relations with the brachial artery, passes obliquely inward and downward, and, as it ex- 
 pands, intersects at right angles the vertical fasciculi proceeding from the epithrochlea 
 and epicondyle of the humerus. These last-mentioned fasciculi also appear to me to be 
 supplementary ; they are continuous with the common tendons of origin of the external 
 and internal muscles of the forearm, and constitute the anterior walls of those two mul- 
 tilocular pyramids, of which one is on the inner, the other on the outer side of the fore- 
 arm, or of that series of trumpet-shaped cavities (cornets), as M. Gerdy calls them, from 
 each of which the muscles of these regions take their origin. I must not omit to men- 
 tion the thick tendinous band, which arises from the entire length of the posterior border 
 of the ulna, divides into two layers to give origin to the flexor carpi ulnaris, and by its 
 internal or deep surface affords attachment to the flexor sublimis. 
 
 In the fascia of the forearm there are numerous foramina for the passage of vessels 
 and nerves, but I shall direct attention to one very large orifice existing in front, at the 
 bend of the elbow, and bounded on the inside by the outer margin of the tendinous ex- 
 pansion of the biceps. This opening establishes a free communication between the sub- 
 cutaneous and the sub-aponeurotic cellular tissue at the bend of the elbow, and leads 
 into a sort of fossa, in which are found the tendon of the biceps, the brachial artery, the 
 commencement of the radial artery, and the median nerve. This fossa is lined by apo- 
 neurotic laminae : on the outside, by the layer which covers the inner surface of the supi- 
 nator longus, the radial extensors, and the flexor sublimis ; on the inside, by the layer 
 which completes the sheath of the pronator teres : it communicates above with the canal 
 of the brachial artery, and below with the canals through which the radial, ulnar, and 
 interosseous arteries and the median nerve proceed downward to the forearm. 
 
 From the internal surface of this fascia a number of laminaj are given off, to form the 
 following muscular sheaths : 
 
 In the anterior region of the forearm, a transverse septum, thicker below than above, 
 divides the superficial layer of muscles from the middle layer, consisting of the flexor 
 sublimis, and also from the deep layer, composed of the flexor profundus digitorum and 
 the flexor longus pollicis. Other septa, passing from before backward, divide the mus- 
 cles of the superficial layer from each other. Lower down the sheaths of the flexor carpi 
 radialis and palmaris longus, which are perfectly distinct from each other, are situated 
 in front of the remainder of the fascia ; and this has led to the statement of some anat- 
 omists, that the fascia is perforated by the tendons of these muscles, especially by that 
 of the palmaris longus. The radial artery has a special sheath throughout its whole ex- 
 tent ; the ulnar artery and nerve have a proper sheath only in the lower part of the forearm. 
 
 In the posterior region of the forearm, the fascia is much stronger than in the anterior. 
 A transverse layer separates the muscles of the superficial from those of the deep layer; 
 and septa, passing from behind forward, subdivide these common sheaths into several 
 smaller ones, corresponding in number to that of the muscles. Thus, we find a sheath 
 for the extensor communis digitorum, a second for the extensor digiti minimi, a third 
 for the extensor carpi ulnaris, and a fourth for the anconeus. The supinator longus and 
 the two radial extensors of the wrist appear to be in the same sheath ; but a more or 
 less distinct membrane surrounds the first of these muscles : the supinator brevis has 
 
318 APONEUROLOGY. 
 
 also a proper sheath. We find a common sheath for the extensor longus poUicis and the 
 extensor proprius indicis. The abductor longus and the extensor brevis poUicis, which, 
 properly speaking, constitute but one muscle, have also a common sheath accompanying 
 them as far as the dorsal annular ligament of the wrist. 
 
 The Dorsal Annular Ligament of the Wrist, and the Dorsal Aponeurosis of 
 
 the Metacarpus. 
 
 The dorsal annular ligament of the wrist (r, Jig. 121) may be considered as a depend- 
 ence of the fascia of the forearm, which in this situation is strengthened by a great 
 number of fibres. It is a band of six or eight lines in width, passing obhquely inward 
 and downward over the extensor tendons of the hand, perforated by a number of open- 
 ings for the passage of vessels, and distinguishable from the fascia of the forearm 
 only by its somewhat greater thickness and by the parallel arrangement of its fascicuU. 
 It arises internally from the pisiform bone and the palmar fascia, passes first over the 
 ulnar side, and then the posterior surface of the carpus, is interrupted by the outer mar- 
 gin of the groove for the two radi2d extensor muscles, takes a fresh origin from that mar- 
 gin, covers the radial side of the wrist, and is inserted partly into the radius, and partly 
 into the fascia of the forearm. From the anterior surface of this thick fibrous band 
 arise several small prolongations, which are interposed between the numerous tendons 
 passing over the dorsal and radial aspects of the carpus, and convert the grooves upon 
 the lower extremities of the radius and ulna into canals. Thus, proceeding from with- 
 out inward, and from before backward, we find, 1 . A sheath for the united tendons of the 
 abductor longus and extensor brevis pollicis ; 2 and 3. Two distinct sheaths opposite 
 the radius : one for the two radial extensors of the carpus, the other for the extensor 
 longus pollicis, which sheaths become blended together lower down into a single com- 
 pletely fibrous sheath ; 4. A fourth sheath, stronger than the preceding, for the extensor 
 communis digitorum and the extensor proprius indicis ; 5. An entirely fibrous sheath for 
 the extensor digiti minimi ; 6. A very strong sheath for the extensor carpi ulnaris, 
 which is prolonged below the ulna, and accompanies the tendon as far as the fifth meta- 
 carpal bone. All these sheaths are lined by synovial membranes,* which extend some 
 distance above the dorsal annular ligament, and, on the other hand, accompany the ten- 
 dons very far down, sometimes even to their insertions. 
 
 The dorsal aponeurosis of the metacarpus is a continuation of the dorsal annular liga- 
 ment : it is composed of a very thin layer of transverse fibres, and separates the exten- 
 sor tendons from the sub-cutaneous vessels and nerves. A very loose, extensible, and 
 elastic cellular tissue takes the place of the synovial membranes over these tendons, and 
 greatly facilitates their movements. 
 
 The Anterior Annular Ligament of the Carpus. 
 
 The deep groove upon the anterior surface of the carpus is converted into a canal by 
 a very thick fibrous band, viz., the anterior ligament of the carpus {g,fig. 118). It com- 
 mences internally by two well-marked origins, separated from each other by the ulnar 
 nerve, one being from the pisiform bone and the tendon of the flexor carpi ulnaris, the 
 other from the unciform bone. The first bundle passes downward, the second trans- 
 versely, and their united fibres, some of which are transverse and others interlaced, ter- 
 minate at the trapezium and the scaphoid, giving off an expansion to the fascia cover- 
 ing the ball of the thumb, with which they are continuous. This ligament is continuous 
 above with the fascia of the forearm, which is much thickened in this situation : it re- 
 ceives in front the expanded tendon of the palmaris longus, and terminates below in the 
 palmar fascia. Its anterior surface gives attachment to most of the muscles of the the- 
 nar and hypothenar eminences. A small portion only of this ligament is generally seen 
 and described, viz., the free portion. If it is wished to obtain a perfect conception of it, 
 the muscles attached to its anterior surface should be carefully removed ; it will then be 
 seen that, on the outside, it describes a curve having its concavity, directed inward, in 
 order to be attached to the scaphoid and the trapezium, and that the sheath of the flexor 
 carpi radiahs is contained in its substance : this sheath is entirely fibrous above, and 
 partly fibrous and partly osseous below, where it converts into a canal the groove on the 
 trapezium. 
 
 While there are almost as many synovial membranes as there are sheaths under the 
 dorsal ligaments of the carpus, on the palmar aspect nine tendons with the median nerve 
 form but a single bundle, which is lubricated by one or two synovial membranes. This 
 synovial membrane* presents a curious arrangement, subject, moreover, to numerous 
 varieties. It lines the posterior surface of the anterior annular ligament of the carpus 
 is prolonged above and below that ligament, and is reflected (without passing between 
 the different tendons) upon the anterior surface of the bundle formed by them and by the 
 median nerve, which is to their outer side. In order to obtain an accurate idea of the 
 termination of this synovial membrane, cut across the tendons at the lower part of the 
 forearm, and turn them forward upon the palm of the hand : it will then be seen that the 
 
 * See note, p. 296. 
 
THE PALMAR APONEUROSIS, ETC. 319 
 
 synovial membrane is reflected upon the ulnar border of the bundle of tendons ; that it 
 lines the posterior surface of this bundle, passing more or less between the tendons, and 
 separating them from each other in a rather irregular manner ; that it is reflected upon 
 the groove of the carpus, prolonged upward and downward much farther than it was in 
 front, and divided below into four small prolongations corresponding to the flexor ten- 
 dons of each finger. Nor is this all, for there is a special synovial membrane for the 
 flexor longus poUicis. In order to expose this, the synovial membrane must be cut 
 through where it is reflected, on its radial side, from the annular ligament on to the me- 
 dian nerve and the anterior surface of the bundle of tendons : a special and very exten- 
 sive synovial membrane will then be seen to pass high up along the tendon of the flexor 
 longus pollicis, and to be prolonged downward as far as the last phalanx of the thumb. 
 
 The Palmar Aponeurosis. 
 
 The palmar fascia (,c,fig. 118) forms a common sheath for all the muscles of the palm 
 of the hand, and is divided into three portions, a middle and two lateral. 
 
 The middle portion. This is the only part generally described as the palmar fascia ; 
 it is triangular and strong, but of variable thickness : it binds down the numerous sub- 
 jacent tendons. It arises from the anterior surface and lower margin of the anterior 
 annular Ugament of the carpus, and from the tendon of the palmaris longus, which may 
 be regarded as its tensor muscle. Between these two origins the ulnar artery pene- 
 trates into the palm of the hand. Not unfrequently the expanded tendon of the palma- 
 ris longus forms a fibrous layer in front of the proper palmar fascia. This fascia is nar- 
 row and thick at its origin, but expands as it proceeds from above downward, and, op- 
 posite the heads of the metacarpal bones, divides into eight prolongations for the four 
 inner fingers. At the seat of this division we find very strong transverse fibres binding 
 the prolongations together, and preventing disjunction of the fingers and laceration of 
 the fascia. By this arrangement four arches are formed, under which the tendons of 
 the flexor muscles pass : between these four arches there are three smaller ones, giving 
 passage to the collater£il vessels and nerves of the fingers, and to the lumbricales, so that al- 
 together there are seven arches. These arches are true fibrous canals. In order perfect- 
 ly to understand their structure, make a vertical incision through the palmar fascia ; it will 
 then be seen that, opposite the arches, tendinous prolongations or tongues are detached 
 from the deep surface of the fascia : these prolongations turn round the sides of the ten- 
 dons so as to embrace them, and become continuous with the anterior or glenoid liga- 
 ment of the metacarpo-phalangal articulations : the same arrangement obtains with re- 
 gard to the three small arches for the vessels and nerves situated between the four prin- 
 cipal tendinous arches. The palmar fascia is, moreover, intimately united to the skin 
 by very numerous prolongations : its deep surface covers the superficial palmar arch of 
 the arteries of the hand, the median and ulnar nerves, and the flexor tendons ; a very 
 loose and extensible cellular tissue separates it from these parts, and facilitates the move- 
 ments of the tendons. From its inner margin is given off a very strong layer, which 
 becomes continuous with the interosseous aponeurosis, and separates the middle from 
 the internal palmar region ; a thinner layer proceeds from its outer margin, and passes 
 down between the muscles of the thenar eminence and the first lumbricalis muscle. 
 This small muscle, called the palmaris brevis (Jb,fig. 118), arises from the inner margin of 
 the middle palmar fascia, and is merely a cutaneous muscle. 
 
 The external and internal palmar fascia, or the thenar and hypothenar aponeuroses. 
 These consist of two rather thin fibrous layers, forming the sheaths of the muscles of 
 the ball of the thumb and those of the little finger : they are both continuous with the 
 middle palmar fascia : the external appears to consist, in a great measure, of an expan- 
 sion from the tendon of the abductor longus pollicis ; and the internal, of an expansion 
 from that of the flexor carpi ulnaris. At the limits between these aponeuroses and the 
 middle fascia are formed two septa, passing from before backward, and dividing the palm 
 of the hand into three distinct sheaths : one median, completed by the interosseous apo- 
 neurosis, and intended for all the flexor tendons and the principal vessels and nerves of 
 the hand ; the other two placed on either side, and binding down the muscles of the the 
 nar and hypothenar eminences. 
 
 The Sheaths of the Flexor Tendons of the Fingers, and their Synovial Mem- 
 branes. 
 After leaving the arches, or, rather, the curious sheaths, formed by the palmar fascia 
 immediately above the corresponding metacarpo-phalangal articulation, each pair of flex 
 or tendons is received into a special sheath, by which they are accompanied down to 
 the last phalanx. It will be remembered that the anterior surfaces of the first and sec- 
 ond phalanges are marked by a longitudinal groove ; to the two borders of this groove is 
 attached a very regular semi-canal of fibrous tissue, which is exactly large enough to 
 contain the two flexor tendons. This very strong sheath preserves its shape when the 
 tendons have been removed ; and a correct idea of its importance may be obtained by 
 observing the effects of contraction of the flexor muscles after it has been divided. This 
 
320 SPLANCHNOLOGY. 
 
 sheath is formed of parallel semicircular laminae, placed one above the other, densely ag- 
 gregated over the bodies of the phalanges, and, for the most part, forming a continuous 
 sheath, but becoming more and more separated, and sometimes even completely disap- 
 pearing opposite the articulations and the articulating extremities of the bones. It ap- 
 pears to me that, in the movements of flexion, these articular rings are pushed into each 
 other. The sheath ceases altogether above the articulation of the second with the ter- 
 minal phalanx. 
 
 A very remarkable synovial membrane,* which is prolonged upward beyond the arch- 
 es formed by the palmar fascia, lines the whole lenth of each osteo-fibrous sheath on the 
 one hand, and on the other is reflected upon the two flexor tendons, affording each of them 
 a sheath, and forms two, often three or four triangular folds, having their bases directed 
 upward, and being perfectly analogous to the so-called adipose ligament of the knee- 
 joint. Of these folds, the superior is situated opposite the upper extremity of the first 
 phalanx, and extends from the tendon of the flexor sublimus to that of the flexor pro- 
 fundus ; the inferior fold passes from the bifurcation of the superficial tendon to the deep 
 tendon ; the others are intermediate, and proceed from the phalanx to the two tendons. 
 These synovial folds can be very well seen by raising and separating the flexor tendons 
 from the phalanges. Not unfrequently the synovial membrane forms a hernia between 
 two of these tendinous rings, either opposite the body of a phalanx, or, still more com- 
 monly, over one of the articulations. We may add, that these synovial folds are proba- 
 bly intended to support the nutritious vessels of the tendons, and not to connect these 
 tendons together. 
 
 SPLANCHNOLOGY. 
 
 General Observations on the Viscera. — External Conformation. — Structure. — Development. 
 — Functions. — Dissection. 
 
 Splanchnology (from crcTMyxvov, viscus) is that division of anatomy which treats of 
 organs more or less compound in their structure. Some of these are contained within 
 the three great visceral cavities (_the viscera), while others are situated without these 
 cavities {organs, properly so called), t 
 
 The brain, the spinal cord, the heart, and the organs of the senses, are generally in- 
 cluded in this division. I have thought it advisable, however, to confine myself here to 
 the description of the digestive, respiratory, and genito-urinary apparatus. The organs 
 of the senses, the brain, and the spinal cord will be studied more advantageously in con- 
 nexion with the rest of the nervous system, and the heart with the other organs of the 
 circulation. 
 
 As the organs we are about to examine have few relations with each other, they do 
 not admit of such extended and important general remarks as those which preceded the 
 osteological and myological divisions. I shall content myself with explaining briefly the 
 method in which the description of each organ should be pursued. 
 
 Every organ presents for consideration its external conformation, its internal confor- 
 mation or its structure, its development, and its functions. 
 
 The External Conformation of Organs. 
 
 The description of the external conformation of organs includes that of their nomen- 
 clature, number, situation, direction, size, shape, and relations. 
 
 Nomenclature. — The nomenclature of organs has not been subjected to so many chan- 
 ges as that of the bones and muscles : the names adopted by the oldest authors have 
 been retained in modern science, and are even used in common language. 
 
 The names of organs are derived, 1. From their uses, as the asophagus (from olu, I 
 convey, and (^ayo), I eat) ; also, the lachrymal and the salivary glands. 2. From their 
 length, as the duodenum. 3. From their direction, as the rectum. 4. From their shape, 
 as the amygdala (the tonsils). 5. From their structure, as the ovaries. 6. From the 
 name of the authors who have best described them, as the Schneiderian membrane, the 
 FaUopian tubes. Lastly, they are conventional words ; for example,the tongue, the liver, &c. 
 
 Number. — Some organs are single ; others exist in pairs. Varieties in number are 
 very common, both by excess and by defect. Thus, three kidneys have been found in 
 the same individual, and there is often only one. Examples have been recorded of in- 
 dividuals having three testicles ; one is uncommon. Lastly, varieties by excess almost 
 always result from the division, and those by defect, from the union or fusion of organs. 
 
 Situation. — This must be considered with regard to the region of the body occupied by 
 an organ, i. e., its general or absolute situation; and also with regard to its relations with 
 neighbouring organs, i. e., its relative situation. Thus, when it is stated that the stom- 
 
 * See note, p. 298. 
 
 t All the viscera are organs, but all the organs are not viscera. The word viscus is probably derived from 
 veacor, I eat, because a great number of the viscera are eng:aged in the functions of nutritioi . 
 
STRUCTURE AND DEVELOPMENT OF ORGANS. 321 
 
 ach occupies the left hypochondrium and the epigastrium, its absolute or general situa- 
 tion is indicated ; but when it is added that this viscus is situated between the oesopha- 
 gus and duodenum, below the diaphragm, and above the transverse mesocolon, its relative 
 situation is implied. 
 
 Many of the organs are subject to varieties of position ; and this constitutes an im- 
 portant point in their history. These varieties of position depend upon congenital oi 
 upon accidental displacement, either affecting the particular organ only, or consequent 
 upon displacement of the neighbouring organs ; or they may result from a change in the 
 size of the organ itself 
 
 Size. — The absolute size of an organ is determined by linear measurements, by the 
 quantity of water which it displaces, and by its weight ; its relative size, by comparison 
 with bodies of a known size, or with other organs. 
 
 The size of organs is subject to a great number of varieties. These depend either on 
 age, as in the liver, testicles, and thymus gland ; on sex, temperament, or on individual 
 peculiarities ; also on the state in which an organ is found : for example, the uterus, pe- 
 nis, and spleen. Lastly, there are some pathological variations, which shoxild not be 
 omitted in a treatise upon descriptive anatomy. 
 
 Figure. — The figure of the organs treated of in splanchnology appears to follow these 
 rules. The double organs do not exactly resemble each other on the right and left sides 
 of the body. The single organs, occupying the median line, are symmetrical ; but most 
 of those which are removed from that line are not symmetrical. Nevertheless, symme- 
 try is not so completely wanting in the viscera belonging to nutritive life, as stated by Bi- 
 chat, for the stomach and the small and great intestines may be divided into two equal 
 halves. 
 
 In regard to their forms, organs are compared, in general, either with familiar objects, 
 or with geometric figures. Thus, a kidney is said to resemble a kidney-bean, and either 
 lung, a cone. In very irregular organs, we merely describe the surfaces and the borders. 
 We shall not find in the viscera the same constancy of form as exists in the organs of 
 relation. 
 
 Direction. — The direction of an organ is determined in the same manner as that of the 
 bones and muscles, viz., by its relations with the imaginary planes surrounding the body, 
 or with the mesial plane. 
 
 Relations. — The figure of an organ being determined, its surface is then divided into 
 regions, the relations of which are accurately ascertained. These regions are generally 
 termed surfaces and borders. As the situation of many organs is subject to great varie- 
 ties, their relations must also vary. Too much cannot be said of the value of an accu- 
 rate knowledge of these relations, from which a number of the most important practical 
 inferences may be derived. 
 
 The Internal Conformation &r Structure of Organs. 
 
 The surface of an organ being well understood, we next proceed to the study of its 
 structure, comprising its colour, its consistence, and its anatomical elements. 
 
 Colour. — The colour both of the surface and the substance of an organ requires to be 
 studied. All variations of colour should be very carefully noted. Age and disease have 
 much influence over it ; and it is often difficult to distinguish positively between its 
 physiological and pathological condition. 
 
 Consistence. — The consistence, density, and fragility of organs are connected with their 
 structure. The specific gravity or density of a single organ only, the lung, has been ac- 
 curately studied, and that in a medico-legal pomt of view. In estimating the con^^isience 
 and fragility of organs, we can only approximate the truth. It is desirable that some more 
 methodical and accurate means should be devised for the estimation of these qualities. 
 
 Anatomical Elements. — The determination of the immediate anatomical elements, or 
 tissues, which enter into the composition of an organ, together with their proportions 
 and their arrangement, constitutes the knowledge of its structure. Every organ has 
 either a cellular, fibrous, cartilaginous, or bony framework. Some organs are provided 
 with muscular fibres, or even with distinct muscles ; they all contain the several kinds 
 of vessels, viz., arteries, veins, and lymphatics ; and they edl possess nerves. The glan- 
 dular organs have excretory ducts. 
 
 In explaining the structure of organs, we shall, generally, confine ourselves to a brief 
 enumemtion of their constituent parts, referring to works on the anatomy of textures for 
 details which would be misplaced in an elementary treatise. 
 
 Tkt Devdopment of Organs. 
 
 The study of the development of organs, and the changes which they undergo at the 
 different periods of intra- and extra-uterine life, is of the greatest interest, at least as re- 
 gards some among them. The formation of the soft parts, however, is not nearly so weL 
 understood as that of the hard tissues, because the most important phenomena of devel- 
 opment occur during the first weeks after conception. The remarks upon this subject 
 will, therefore, generally point out some hiatus to be filled up. 
 
 Ss 
 
822 SPLANCHNOLOGY. 
 
 The Functions of Organs. 
 The functions or uses of organs flow so naturally from their anatomical description, 
 that we shall follow the example of the greater number of anatomists, in adding to such 
 description a short account of the functions of an organ. We shall only notice particu- 
 larly those uses of organs which depend immediately upon their structure, referring to 
 physiological works for the details and discussions of yet disputed points in the science 
 of functions. No part of anatomy excites so much curiosity and interest as splanchnol- 
 ogy, in consequence of the importance of the organs of which it treats. Without a 
 knowledge of this department of anatomy, it is impossible to understand the mechanism 
 of functions the most indispensable to life ; and as the organs themselves are the seat 
 of the greater part of the lesions which are assigned to the physician, as well as of many 
 of those which fall under the care of the surgeon, most of the fundamental questions of 
 the heeding art require a profound knowledge of these organs. 
 
 The Dissection of the Viscera. 
 
 The dissection of organs does not consist in merely isolating them from surrounding 
 parts, which, as far as regards those contained in the visceral cavities, is done by sim- 
 ply laying open the latter, but in the separation of their anatomical elements or tissues. 
 For this purpose, injections of the most delicate kind, maceration, boiling, preservation 
 in alcohol, desiccation, the action of acids, in short, aS\. the resources of his art, are em- 
 ployed by the anatomist. 
 
 Having made these preliminary observations, we shall now describe in succession the 
 organs of digestion, the organs of respiration, and the genito-urinary apparatus. 
 
 THE ORGANS OF DIGESTION AND THEIR APPENDAGES, 
 
 ALIMENTARY OR DIGESTIVE CANAL. 
 General Observations. — Division. — Mouth and its Appendages. — Lips. — Cheeks. — Hard and 
 Soft Palate. — Tonsils. — Tongue. — Salivary Glands. — Buccal Mucous Membrane. — Pha- 
 rynx. — (Esophagus. — Stomach. — Small Intestine. — Large Intestine. — Muscles of the Pe- 
 rineum. — Development of the Intestinal Canal. 
 
 The organs of digestion form a long canal, the alimentary or digestive canal, extending 
 from the mouth to the anus, which receives alimentary substances, induces in them a 
 series of changes, by which they are rendered fit to repair the losses incurred by the 
 body, and, moreover, presents a vast absorbent surface for the action of the lacteal ves- 
 sels. The entire series of these organs constitutes the digestive apparatus. 
 
 Tlie existence of an alimentary canal is one of the essential characters of an animal. 
 In consequence of possessing it, animals may be detached from the soil, so as to move 
 from place to place. In the lowest species, the entire animal is nothing more than an 
 alimentary sac, having a single opening, and formed by a reflection of the skin ; so that, 
 according to the beautiful observation of Trembley, when polypes are turned inside out, 
 the digestive process is performed as well by their external as by their internal surface. 
 Ascending in the scale of animals, the canal soon presents two openings, acquires larger 
 dimensions, becomes more or less convoluted, and is distinct from other systems of or- 
 gans. A skeleton clothed by muscles is interposed between it and the skin. It becomes 
 more and more voluminous, in proportion as the nutritive materials and the textures of 
 the body differ more widely in their chemical composition. What a difference there is, 
 in this respect, between certain fishes, in which the alimentary canal is not nearly so 
 long as the animal, and some herbivora ; the ram, for example, in which it is twenty- 
 seven times the length of the body. Carnivorous animals, again, have a short and nar- 
 row alimentary canal. Man, being destined to live both upon animal and vegetable sub- 
 stances, occupies, as it were, a middle station between the herbivora and carnivora. 
 
 General Situation. — The digestive canal is situated in front of the vertebral column, 
 with the direction of which the straight portion of the canal accurately corresponds, 
 while its tortuous part is distant from, though invariably connected with it by means of 
 membranous attachments. It commences at the lower part of the face, traverses the 
 neck and the thorax, penetrates into the abdominal cavity, which is almost exclusively 
 intended for it, and the dimensions and mechanism of which bear strict relation to the 
 functions of the alimentary canal ; and it terminates at the outlet of the pelvis, anterior 
 to the coccyx, by the anal orifice. Its upper part is in immediate relation with the or 
 gans of respiration ; its lower, with the genito-urinary apparatus. 
 
 Dimensions. — The length of the digestive canal has been calculated to be seven oi 
 eight times that of the body of the individual. Its diameter is not equal through its 
 whole extent ; and its alternate expansions and contractions establish very distinct lim- 
 its between its several portions. The largest portion is, undoubtedly, that which re- 
 ceives the name of the stomach ; the narrowest parts are the cervical portion of the 
 oesophagus, the pyloric opening of the stomac-h, and the ileo-caecal orifice. It is impor- 
 
GENERAL REMARKS. 
 
 tant to remark, that the transverse dimensions of an alimentary canal have, to a certain 
 extent, an inverse ratio to its length. Thus, a very wide intestinal canal is generally 
 less remarkable for length. This remark is illustrated by comparative anatomy in the 
 fact that, in the horse, an herbivorous animal, the intestinal canal is shorter, but, at the 
 same time, of a much greater calibre than in the ruminantia, which are also herbivorous. 
 
 Direction. — The upper or supra-diaphragmatic portion of the alimentary canal, through 
 which the food merely passes, is straight ; the sub-diaphrjigmatic portion is very much 
 convoluted upon itself, but again becomes straight before its termination. 
 
 General Form. — The digestive apparatus forms a cylindrical continuous canal, in which 
 we have to consider an external and generally free serous surface, and an internal mu- 
 cous surface. 
 
 Struclure. — The digestive canal is composed of four membranes or tunics : 1 . The 
 most external is the serous or peritoneal coat, also named the common tunic, because it is 
 conunon to almost all the organs in the abdominal cavity. This membrane, which may 
 be regarded as an accessory tunic, is often incomplete, and even entirely wanting through- 
 out the supra-diaphragmatic portion of the digestive canal. At the same time that it 
 constitutes the external covering of this canal, it separates it from the neighbouring parts, 
 facilitates its movements, and forms certain bands, which maintain the several portions 
 of the canal more or less fixedly in their proper situations. The serous membranes, of 
 which this external tunic is only a dependance, are shut sacs, which, on the one hand, 
 line the walls of the cavities to which they belong, and, on the other, are reflected upon 
 the organs contained therein,* without, however, including them within their ovm prop- 
 er cavity. 
 
 A serous membrane may be compared to a balloon, or, rather, to a double nightcap ; 
 its internal surface is free, smooth, always moistened with serosity, and its parietal and 
 visceral portions are in contact with each other : its external surface is adherent, t 
 
 2. Beneath the serous coat is situated the muscular coat, consisting of two layers : one su- 
 perficial, composed of longitudineil fibres ; the other deep, and composed of circular fibres. 
 
 These fibres are colourless, like almost all the muscles of nutritive or organic life. J 
 
 3. The fibrous coat, interposed between the muscular and mucous coats, may be regard- 
 ed as constituting the framework of the alimentary canal. It consists of dense areolar 
 cellular tissue.^ 
 
 4. The mucous coat or membrane forms the internal lining of the digestive canal. Ev- 
 ery cavity having a communication with the exterior is hned by a mucous membrane, 
 so called on account of the mucus with which it is constantly lubricated. 
 
 In mucous membranes generally, we find, 1. A dermis or chorion, 2. Papilla or villosi- 
 ties, which give them a velvety appearance ; hence the designation papillary, villous, or 
 velvety membrane frequently given to them. 3. On the outer surface of the dermis we 
 find a very dense network of capillary vessels, which may be completely injected from the 
 veins, but less easily and less completely from the arteries. 4. Either follicles or small 
 closed sacs are seen here and there in the substance of mucous membranes ; but they 
 are not essential, as the name follicular, given to these membranes by Chaussier and 
 some other anatomists, would seem to indicate. 
 
 * [Hence the terms parietal and visceral, applied to these two portions of a serous membrane (see Jig, of 
 the testis, letters p and v). 
 
 In consequence of the existence of an aperture in the free extremity of each Fallopian tube, the peritoneal 
 cavity in the female is an exception to the general rule, that serous membranes form shut sacs, not communi- 
 cating with the external medium.] 
 
 t [Serous membranes are transparent, colourless, extremely thin, and highly distensible and elastic. They 
 are composed of a basis of cellular tissue, loose and connected to the adjacent tissues externally, more or less 
 condensed towards the inner and free surface of the membrane, and covered with an extra- vascular epithelium, 
 consisting of a single layer of nucleated cells, Ilattened into the form of scales, and arranged parallel to that 
 surface. Cilia have been detected on many serous membranes, as on the peritoneum and pericardium of the 
 frog ; on the same parts, and also on the pleura and lining membrane of the ventricles of the brain in certain 
 mammalia ; and in the latter situation in man. Bloodvessels ramify in the sub-serous cellular tissue, but do 
 not penetrate far towards the free surface, where they are entirely wanting. Lymphatics also exist in the 
 sub-serous tissues, but have not been found in the membranes themselves ; nor have nerves been traced into 
 them. The fluid secretion found in serous cavities appears to be of an albuminous nature.] 
 
 t [The involuntary muscular fibres of the alimentary canal (according to Dr. VV. Baly) consist of bands, va- 
 rying from o^j'g-jjth to , A ^ th of an inch in diameter, apparently formed of flattened tubes, in the parietes of 
 which are seen, at irregular intervals, numerous transparent oval or linear bodies, sometimes very difiicult of 
 detection : they are believed to be the nuclei of the primitive cells, from which the fibre itself is developed. 
 These fibres contain no varicose filaments, nor do they present any transverse striK, like those of animal life 
 (see p. 194). Moreover, although they have a parallel arrangement in the fasciculi into which they are col- 
 lected, the fasciculi themselves are irregularly interlaced, at the same time that they all pursue a common 
 direction. 
 
 The muscular coat of nearly the entire alimentary canal consists essentially of these involuntary or organic 
 muscular fibres ; but at the commencement and termination of the canal, where the muscular systems of ani- 
 mal and organic life come into relation with each other, this tunic appears also to consist of fibres resembling 
 those of the voluntary muscles. Thus, at the upper part of the (Esophagus, fibres containing varicose filaments, 
 and possessing the cross stri<e, were detected by Schwann ; and it has been shown by Valentin and Ficinns, 
 that these exist all along the oesophagus, and that indistinctly striated fibres are found even at the cardiac end 
 of the stomachs of many mammalia, and of man. Similar fibres were observed by Ficinus in the rectum, near 
 the sphincter ani.] 
 
 I) [It is frequently called the cellular coat ; and, from its white appearance, has been termed (like all othei 
 white textures) the nervous tunic] 
 

 SPLANCHNOLOGY. 
 
 All mucous membranes are covered by an extremely delicate pellicle, which may be 
 readily detected by means of a simple lens. Injections made by the arteries and veins 
 never penetrate it, nor is it reddened by inflammation. I have accidentally injected it, 
 hovirever, by means of a tube containing mercury, used for injecting the lymphatics by 
 pricking the mucous membrane in different places as superficially as possible. The vas- 
 cular network, thus injected, is exceedingly delicate ; the small globules of mercury 
 traversing it in all directions, so as to form rapidly a silvery areolar layer. I have seen 
 this in the mucous membrane of the nose ; on the conjunctiva, both over the sclerotic 
 and over the cornea ; on the mucous membrane of the vagina, of the tongue, and of the 
 cheeks. It is very remarkable that the mercury never passes from this network ei- 
 ther into the veins or the arteries ; and, moreover, that if the tube pierces a little too 
 deeply, the veins are injected, but not the epidermic capillary network. It is evident, 
 therefore, that this network has no communication either with the arteries or the veins. 
 It probably belongs to the lymphatic system, although I have never observed the lymphat- 
 ic vessels filled from it.* 
 
 Vessels and Nerves. — Vessels and nerves also enter into the formation of the aliment- 
 Fig. 139. ary canal : for example, we find a very abundant supply of 
 
 branches from the adjacent arterial trunks ; an immense num- 
 ber of veins, of which those from the sub-diaphragmatic por- 
 tion of the canal terminate in the vena portae ; absorbent ves- 
 sels, divided into lymphatics and lacteals ; and, lastly, nerves, 
 almost all of which proceed from the ganglionic system, ex- 
 cepting the pneumogastric and glosso-pharyngeal nerves. 
 
 Division of the Digestive Canal. — The digestive canal has 
 been divided into several parts, from differences both in their 
 anatomical characters and their functions. One principal di- 
 vision, which deserves to be retained, is into a supra-diaphrag- 
 matic and a sub-diaphragmatic portion. The supra-diaphragmat- 
 ic portion comprehends the mouth, the pharynx, and the asoph- 
 agus. The infra-diaphragmatic portion includes the stomach 
 (a h, fig. 139), the small intesti7ie, subdivided into the duodenum 
 (b c), and the jejunum and ileum (c d) ; and the large intestine, 
 somewhat arbitrarily divided into the ceecum {d e), the colon {d 
 h), and the rectum (h i). The appendages of the digestive ca- 
 nal consist of the salivary glands, connected with the mouth ; 
 of the liver and the pancreas, connected with the duodenum ; 
 and of the spleen, which may be regards'^ .^s an appendage of the liver. 
 
 The Mouth and its Appendages. 
 
 The mouthy is a cavity situated at the entrance of the digestive passages. It occu- 
 pies the lower part of the face, and is situated between the two jaws, below the nasal 
 
 * [The lining membrane of the digestive apparatus, forming part of the gastro-pulmonary system of the 
 mncou.s membranes, extends not only throughout the entire alimentary canal, but also along the ducts of the 
 various glands which pour their secretions into it. 
 
 Structure m general. — Mucous membranes are usually soft, pulpy, incapable of great distension, easily la- 
 cerated, soraevfhat opaque, and when free from blood, of a pale grayish or ashy hue. The dermis or chorion 
 (analogous to that of the skin) is a basis of cellular tissue, of very variable thickness ; its attached surface is 
 connected to the subjacent textures, either immovably, as in the nasal cavities and on the tongue, or loosely, 
 as in the gullet and stomach. The pellicle or epithehum with which its surface is always covered (correspond- 
 ing to the epidermis of the skin) adso varies much in thickness in different situations ; it consists of transpa- 
 rent nurJeated cells, according to the form and arrangement of which it receives its name. Thus, in the 
 squamous epithelium, there are generally (as in the mouth and gullet) several layers of cells ; of these the 
 deepest are vesicular, and contain a comparatively large nucleus ; those im the surface are flattened out into 
 polygonal scales, from the centrj of which the nucleus has nearly disappeared, while the intermediate cells 
 present intermediate transitional forms. The nucleated cells of the columnar epithelium (found, for example, 
 in the stomach and intestines) are developed into oblong cylinders, arranged in a single scries, like basaltic 
 columns, perpendicularly to the surface of the dermis. In some situations, as in the nasal cavities and air 
 passages, cilia are attached to the free extremities of the cylinders of the columnar epithelium, but no cilia 
 have been detected in any part of the alimentary canal of man, or the warm-blooded animals : the superficial 
 cells of the epithelium of mucous membranes are continually being thrown off by a process of desquamation. 
 The different mucous membranes differ in vascularity ; the network of capillary vessels in the dermis becomes 
 closer or denser near its surface ; the lymphatic vessels also form a network in the same situation; but the 
 epithelium, though organized, is, as stated in the text, perfectly extra-vascular. 
 
 Mucous membranes are also more or less abundantly supplied with nerves. 
 
 When boiled they yield no gelatine, or, rather, only as much as would proceed from the cellular tissue and 
 vessels they contain. The fluid secreted by them, or mucus, is viscid, transparent, and colourless, miscible 
 with, but not soluble in water, and not coagulated by heat. It contains, besides the desquamated epithelium 
 scales, proper granular globules, yjg-ff '"•''^ '" diameter, and having a very close resemblance to the globules 
 of pus. According to Berzelius, mucus consists of water, a few salts, albumen, and a peculiar animal sub- 
 stance, which he calls mucous matter. This latter, when dried, swells on being placed in water, but, like- 
 fresh mucus, is insoluble in that fluid, either hot or cold; it is shghtly soluble in dilute acetic and nitric acids, 
 and in caustic alkalies. 
 
 The peculiarities presented by particular portions of the mucous membranes, and the structure of the pa- 
 pillae, villi, follicles, &c., found in some parts of them, will be separately noticed, as ojiportunity offers.) 
 
 t The meaning of the word mouth, in anatomy, differs from the ordinary acceptation of the term, which is 
 •sually applied, not to the buccal cavity, but to its orifice. 
 
THE LIPS. 32d 
 
 fossffi, between the cheeks, behind the lips, and in front of the pharynx. It constitutes 
 a very complicated apparatus, in which are per- p^g j4q 
 
 formed the several acts of mastication, tasting, 
 and insalivation, the commencement of the act of 
 deglutition, and the articulation of sounds. 
 
 The dimensions of the buccal cavity are great- 
 er than those of the succeeding portion of the ali- 
 mentary canal ; hence bodies may be introduced 
 into it which are too large to pass through the 
 constricted parts of that canal.* The size of the 
 mouth presents every intermediate degree be- 
 tween complete closure with the jaws in contact 
 and leaving no interval between them, and ex- 
 treme expansion, when the buccal cavity repre- 
 sents a quadrangular pyramid, the base of which 
 is directed forward, and the apex backward. Au 
 increase in the capacity of the mouth may also 
 be effected in the transverse direction by the dis- 
 tension of the cheeks, and in the antero-posterior 
 direction by a projection of the lips fiJrward. 
 
 In studying the relative proportions of the sev- 
 eral diameters of the buccal cavity, it is found 
 that none of them predominates in man, while, 
 in the lower animals, the antero-posterior is by 
 far the longest : this depends partly on the great size of their nasal cavities, and partly 
 on the length of their jaws. In connexion with this subject, we may remark, that in 
 the animal series there is an inverse ratio between the size of the cavity of the cranium 
 and that of the gustatory and olfactory cavities. 
 
 In man, the direction or axis of the mouth is horizontal — an arrangement which is con- 
 nected with his destination for the biped position. If man assumed the attitude of a 
 quadruped, the axis of his mouth would be vertical ; whereas, in the lower animals, it is 
 directed obliquely to the horizon. 
 
 Form. — The mouth {Jig. 140) represents a perfectly symmetrical oval cavity, the great 
 extremity of which is in front. It has an upper wall, viz., the arch of the palate (a) ; a 
 lower wall, consisting principally of the tongue (i) ; a posterior icall, formed by the velum 
 palati (c) ; an anterior wall, composed of the lips {d) on one plane, and of the alveolar 
 arches and the teeth (e) on another ; and two lateral walls, formed by the same arches, 
 by the teeth, and by the cheeks. It lias two openings : one anterior (m), constituting the 
 orifice of the mouth ; the other posterior {2, Jigs. 140, 141), establishing a communication 
 between the buccal cavity and the pharynx, and, on account of its narrowness, called the 
 isthmus of the fauces . 
 
 We shall now describe these parts in succession, excepting the maxillary bones and 
 the teeth, which have been already treated of The salivary glands, which pour their 
 secretions into the buccal cavity, will be described as appendages to it. 
 
 The Lips. 
 
 The lips, forming the anterior wall of the mouth, are two movable, extensible, and 
 contractile curtains, which circumscribe its orifice. They are distinguished into upper 
 and lower. Their direction is vertical, like that of the alveolar and dental arches, upon 
 which they are applied. This direction is peculiar to the human species, and is more 
 marked in the Caucasian race; lips projecting forward, like those of the lower animals, 
 and not placed upon the same vertical plane, give a mean expression to the physiogno- 
 my. The depth of the lips is measured by that of the alveolar and dental arches. The 
 upper is deeper than the lower lip. 
 
 The two lips offer for our consideration an anterior or cutaneous surface, a posterior 
 or mucous surface, an attached and a free border, and two commissures. 
 
 The Anterior Surface. — In the upper lip this surface presents along the median line a ver- 
 tical furrow, the sub-nasal groove, commencing at the septum of the nose, and termina- 
 ting belovi^ in a tubercle, which is more or less prominent in different individuals. This 
 furrow is the vestige of a division in the lip, natural to many mammalia. The malfor- 
 mation, termed single hare-lip, always occupies one of the edges of this groove ; in double 
 hare-lip both of them are affected. On each side, the upper lip is convex, and covered 
 with a slight down in the female, and before puberty in the male, but after that period 
 with long and stiff hairs directed obliquely outward. The aspect of the anterior surface 
 of the lower lip is inclined a little downward ; the middle portion only of this lip, which 
 presents no median depression, is covered with hairs. 
 
 * As a peneral rule, the proportion between the different parts of the alimentary canal is such, that the up- 
 per portion will not admit bodies too Urge for the lower ; and though the buccal cavity forms an exception to 
 the rule, it is because the food, while it remains in that situation, is under the influence ot the will. 
 
326 SPLANCHNOLOGY. 
 
 The Posterior Surface. — Each lip is free behind, excepting in the median h'ne, where 
 we find a small fold of mucous membrane called the frcenum labii : it is more marked m 
 the upper than in the lower lip. This surface is always moist, and is in contact -with 
 the alveolar and dental arches. The complete independence of the lips, as regards the 
 maxillary bones, explains the extreme mobility of these membranous organs.* 
 
 Adherent Borders of the Lips. — The lips are bounded at their posterior surface by the 
 reflection of the mucous membrane upon the jaw, so that there is a deep and very re- 
 markable furrow between the lips and the maxillary bones, which may be regarded as 
 an anterior buccal cavity, or the vestibule of the mouth. The upper lip is bounded in front 
 by the base of the nose ; on each side it is separated from the cheeks by the projection 
 of the inner margin of the levator labii superioris alaeque nasi ; the lower lip is bounded 
 in the median line by a transverse depression situated between it and the chin, called 
 the mento-labial furrow, which is remarkable for the perpendicular direction of the hairs 
 growing upon it ; on each side it is separated from the cheeks by the projecting inner 
 margin of the triangularis oris. 
 
 The hue or furrow which separates cm either side the lips from the cheek commences 
 at the ala of the nose, and is c£illed the naso-labial line .•+ it would be more appropriately 
 named the bucco-laJnal line or furrow. 
 
 The boundaries between the lips and the cheeks are, then, entirely artificial ; the two 
 lips, taken together, represent an ellipse, the longest diameter of which is transverse. 
 
 The Free Borders of the Lips. — ^The free borders of the lips are rounded, are covered 
 by a red integument, intermediate in character between skin and mucous membrane, and 
 are marked by folds or wrinkles directed at right angles to the length of the lips, and 
 produced by the contraction of the orbicularis oris muscle. These free borders, which 
 are, as it were, everted, especially that of the lower lip, present anteriorly a well-marked 
 line of separation between the skin and the mucous membrane ; they describe an undu- 
 lating line, which attracts the attention of the painter more than that of the anatomist. 
 
 The chief characters of the free margin of the upper lip are, a slight projection in the 
 middle hne, and a slight depression on either side : those of the free border of the lower 
 lip are a median depression and two lateral projections ; on meeting together, these bor- 
 ders come into accurate contact, and completely close the opening of the mouth. The 
 free margins of the lips are, moreover, their thickest part, and they are thicker in the 
 middle than at each extremity ; their thickness also varies greatly in different individ- 
 uals. In general, thick lips are regarded as indicating a scrofulous diathesis ; but in 
 forming an opinion upon this subject, it is necessary to distinguish carefully between 
 size resulting from hypertrophy of the muscular layer, and that which is caused by an 
 excess of skin and cellular tissue. In the Ethiopian race, the size of the lips is entirely 
 due to the great development of the muscles. 
 
 The Commissures. — The lateral extremities of the free margins of the lips are thin, and 
 by their union form the angles or commissures of the lips (from committo, to join together). 
 
 The Anterior Orifice of the Mouth. — The free edges of the lips intercept a transverse 
 fissure, viz., the anterior opening of the mouth. The variable size of this orifice in man 
 has given rise to the distinctions of middle-sized, large, and small mouths : the difference, 
 however, is confined to the opening, and does not at all affect the buccal cavity properly 
 so called. The anterior opening of the lips is also exceedingly dilatable, and, accord- 
 ingly, admits the introduction of very large bodies, and renders the exploration of every 
 part of the cavity of the mouth comparatively easy. 
 
 Structure of the Lips. — The lips are composed of two tegumentary layers, one cutane- 
 ous, the other mucous ; of a muscular layer ; of a series of glands ; and of vessels, 
 nerves, and cellular tissue. 
 
 The Cutaneous Layer. — This is remarkable for its density and thickness, for the size 
 of the hair follicles, which are partially situated beneath it, and for its intimate adhesion 
 to the muscular layer ; so that it is impossible to separate them by dissection without 
 encroaching upon one or the other. This layer may be regarded as the framework of 
 the lips. It is endowed with an exquisite sensibility, and, in many animals, possesses 
 so delicate a sense of touch, that the slightest movement of the extremities of the long 
 hairs with which it is provided at once warns the animal of the presence of approach- 
 ing objects. 
 
 The Mucous Layer. — This is remarkable from the existence of an epithelium upon it, 
 which can be very easily demonstrated. It covers the free edge of the hps, so that, by 
 a rare exception, a portion of this mucous membrane is habitually exposed to the exter- 
 nal air. It adheres more firmly at the free edge of the lip than elsewhere.t 
 
 The Glandular Layer. — This is a thick layer, situated between the mucous and the 
 
 * Mammalia alone have lips that are movable, independently of the jaws ; but this independence is still 
 more marked in man. 
 
 t Much importance is attached to this furrow in semeiology. It is termed the abdominal line, because it 
 becomes remarkably distinct in diseases of the abdomen. 
 
 t [The mucous membrane upon the free borders of the lip is provided with papillse. Its epithelium, and, 
 indeed, that of the entire mouth, is sqiuanous.l 
 
THE LIPS. 327 
 
 ..muscular layers, and causing an elevation of the former. It consists of small spheroida. 
 
 i^glands of unequal size, placed close to each other, but perfectly distinct ; when examined 
 
 with a lens, they resemble small salivary glands, each being provided with an excretory 
 
 duct, opening by a separate orifice upon the posterior siurface of the mucous membrane.* 
 
 These are true labial salivary glands, and not muciparous follicles. 
 
 The Muscular Layer. — This is composed essentially of a single proper muscle, the or- 
 bicularis oris, into which almost all the muscles of the face are inserted, viz., the levator 
 labii superioris alaeque nasi, the levator labii superioris, the depressor alae nasi, the naso- 
 labialis, and the zygomaticus minor (where it exists) for the upper lip ; the quadratus 
 menti and the levator labii inferioris for the lower lip ; the buccinator (which we have 
 regarded as forming the orbicularis by its bifurcation extending to both lips), and the 
 zygomaticus major, the triangularis oris, the levator anguli oris, and the risorius of San 
 torini (where it exists) to the commissures. Including the orbicularis oris, there are 
 twenty-five muscles. The differences presented by the free edges of the lips in differ- 
 ent individuals depend upon variations in the thiclcness of the corresponding portion of 
 the orbicularis. 
 
 No fibrous tissue enters into the composition of the lips and their commissures, which 
 are exclusively formed of fleshy fibres : hence they are extremely extensible, a circum- 
 stance of which the surgeon avails himself in operating upon parts situated in the buc- 
 cal cavity and pharynx. 
 
 Vessels, Nerves, and Cellular Tissue. — Few parts are so abundantly provided with vessels 
 and nerves as the Jips. The arteries of the lips are derived from two principal sources : 
 the coronary arteries arise from the facial ; the buccal, infra-orbital, and alveolar arteries 
 destined for the upper lip, and the mental artery for the lower lip, arise from the internal 
 maxillary. The sub-mental artery, a branch of the facial, and the transversalis faciei, a 
 branch of the temporal, also give off some ramifications to the lips. The veins bear the 
 same names, and follow the same direction as the arteries ; the lymphatic vessels, which 
 are little known, terminate in the glands at the base of the jaw. The nerves are derived 
 from two distinct sources, viz., from the fifth and the seventh pairs of cranial nerves. 
 
 The cellular tissue contained in the substance of the lips is essentially of a serous 
 nature. It is liable to a considerable amount of serous infiltration ; but even in the fat- 
 test individuals it contains only a very small quantity of adipose tissue. 
 
 Development. — According to Blumenbach and most modem anatomists, the upper lip 
 is originally developed from three points or three distinct parts : one median and two 
 lateral. Some have even gone farther, and have maintained that the median point itself 
 is originally formed of two lateral halves, which become united at a very early period. 
 This hypothesis is founded partly upon the nature of the divisions in simple and double 
 hare-lip, each of which has been assumed to be nothing more than an arrest of develop- 
 ment ; also, upon the mode of development of the superior maxillary bones, the alveolar 
 border of which, it is said, is composed of four pieces : two median or incisor, and two 
 lateral ; and, lastly, upon the permanent existence of these divisions in some animals. 
 In opposition to this view, however, we may state, first, the absence in the human foetus 
 of distinct bony pieces, corresponding to the ossa incisiva of the lower animals, for all 
 that can be distinguished is a fissure, the mere trace of a separation (see Development of 
 the Superior Maxilla, p. 51) ; and, secondly, that at no period of foetal life can we demon- 
 strate the existence of any division in the upper lip. This lip has always appeared to 
 me to consist of a single piece from the earliest period of its formation. The same 
 may be said of the lower lip, which, according to authors, is developed from two lateral 
 halves. At no period of foetal life can any such division be detected. + I do not even 
 know an example of malformation in which such an arrangement existed. 
 
 The length of the lips of the new-bom infant is well adapted for the act of sucking, and 
 depends upon the absence of the teeth. To the same cause, and to the wasting of the 
 alveolar borders, the length of the hps in advanced age must be referred. 
 
 Uses. — The lips, constituting the anterior wall of the mouth, form a sort of barrier in 
 front of the teeth and alveolar arches, by which the saliva is retained within that cavity. 
 So great is the importance of the lips in preventing a continual escape of the saliva, that 
 in cases where they have been destroyed, the constant draining away of that fluid may 
 become a cause of exhaustion, and even of death.J 
 
 They are employed, also, in drinking, sucking, and blowing ; in playing upon wind-in- 
 struments, and in uttering articulate sounds. They are also of great importance in the 
 expression of the passions, which, as we have seen, influence all the muscles of the face. 
 Pride, contempt, joy, grief, anger, and every possible gradation Of feeling, are depicted 
 in a striking manner upon the outline of the lips. The mouth is more particularly the 
 
 * When these orifices are obliterated, the dilated excretory ducts are transformed into salivary cysts, which 
 may acquire a very large size. 
 
 t The admirable researches of M. Velpeau upon embryology fully confirm the results at which 1 have ar- 
 rived. 
 
 t This use is principally confined to the lower lip, and it is remarkable that this lip is never affected by con- 
 genital fissure. Another singular, and also totally inexplicable fact, is, that cancer, which is so common a dis 
 ease, never affects the upper, but invariably the lower lip 
 
 \ 
 
328 SPLANCHNOLOGY. 
 
 seat of grimaces, which are nothing more than the expression of passions ridiculously 
 exaggerated. 
 
 The Cheeks. 
 
 The cheeks form the lateral walls of the mouth and the sides of the face. They are 
 bounded internally by the reflection of the mucous membrane upon the maxillary bones ; 
 externally their limits are much less defined, and are thus determined on each side of 
 the face ; in front, by the bucco-labial furrow, which separates them from the lips ; behind, 
 by the posterior border of the ramus of the lower jaw ; above, by the base of the orbit ; 
 and below, by the base of the lower jaw. The cheeks, then, comprise three very distinct 
 regions : the malar, the masseteric, and the buccal, properly so called. Each cheek is 
 quadrilateral in form, and presents, 1. An external or cutaneous surface, on which is ob- 
 served, above, tl)e projection of the cheek, called the malar eminence, and lower down, a 
 surface, which is convex and smooth in stout persons, but hollow and wrinkled in the 
 emaciated ; 2. An internal or mucous surface, free, and corresponding to the alveolar and 
 dental arches. On this surface is situated the orifice of the Stenonian duct, opposite the 
 interval which separates the first from the second upper large molar tooth. 
 
 Structure. — Each cheek, properly so called, is composed of the following parts : the 
 malar bone and the ramus of the lower jaw ; a cutaneous layer, increased in thickness 
 by a great quantity of fat ; a mucous, a glandular, a muscular, and an aponeurotic layer ; 
 some vessels and nerves, and an excretory duct. We shedl make a few remarks upon 
 these different layers, commencing with the skin. 
 
 The skin is remarkable for its firmness and vascularity over the cheek bone, and also 
 for the facility with which it is injected, or becomes pale under the influence of the moral 
 feelings ; it is covered with hair on the lower and back part in the adult male 
 
 The mucous membrane is a continuation of that of the lips, and presents the same char- 
 acters. 
 
 The glandular layer is formed by the buccal salivary glands, which exactly resemble the 
 labial glands, but are smaller, and, like them, cause projections of the mucous membrane, 
 upon which they open by distinct orifices. Two of these glands have obtained a partic- 
 ular appellation, because they are not subjacent to the mucous membrane, but are situ- 
 ated between the buccinator and the masseter muscles : they are called the molar glands. 
 Their excretory ducts open opposite the last molar tooth. 
 
 The muscular layer is formed, in the masseteric region, by the masseter and a part of 
 the platysma ; in the malar region, by the orbicularis palpebrarum ; in the buccal region, 
 properly so called, by the buccinator, and the two zygomatici. 
 
 The aponeurotic layer is formed by the aponeurosis of the buccinator muscle. 
 
 The adipose layer is thin in the malar and masseteric regions, and very thick in the 
 buccal region, properly so called. Bichat has, moreover, pointed out a mass of fat in the 
 substance of the cheek, between the buccinator and the masseter. It is highly devel- 
 oped in the infant, and vestiges of it are found even in the most emaciated individuals, 
 and in extreme old age. 
 
 The arteries of the cheeks come partly from the facial and the transverse artery of 
 the face, and partly from the internal maxillary : the branches from the internal maxil- 
 lary belong to the infra-orbital, the inferior dental, the buccal, the masseteric, and the 
 edveolar arteries. 
 
 The veins bear the same name, and follow the same course, as the arteries. 
 
 The lymphatic vessels pass into the cervical and parotid lymphatic glands. 
 
 The nerves of the cheeks, like those of the lips, are derived from two sources, viz., 
 the buccal and malar nerves, from the portio dura of the seventh pair, and the buccal, 
 masseteric, infra-orbital, and mental branches of the fifth pair. 
 
 The cheek is perforated by the duct of Steno {s, fig. 144), which runs horizontally for- 
 ward, below the malar bone. 
 
 Development. — The absence of the teeth, the presence of a large quantity of fat (more 
 especially the great size of the mass above noticed), the want of height in the superior 
 maxilla from the non-development of the sinus, and, lastly, the obtuse angle of the lower 
 jaw, give to the cheek of the infant its characteristic fulness. The loss of the teeth, 
 and the wasting of the alveolar borders in the aged, diminish the inter-maxillary space ; 
 so that their emaciated cheeks become disproportionately long, and, consequently, dis- 
 play a looseness which forms one of the chief peculiarities in their physiognomy. At 
 puberty, the cheeks of the male are covered with hair. 
 
 Uses. — The cheeks form lateral active walls of the mouth, which, closely applying 
 themselves against the alveolar arches and teeth, force the food between the latter, and 
 thus assist in mastication. They are employed, also, in suction, in the articulation of 
 sounds, and in plapng upon wind-instruments. In the expression of the passions, they 
 assist rather by changes in their colour than by any distinct movements. 
 
 The cheeks and the lips constitute the outer wall of a supernumerary buccal cavity, 
 of which the inner wall is formed by the alveolar borders and the teeth. This cavity, a 
 sort of vestibule to the buccal cavity, properly so called, is very dilatable. It mav be 
 
THE PALATINE ARCH AND THE GUMS. 329 
 
 tfuusidered as a kind of reservoir, in which the food is deposited, in Older to be submitted 
 in successive portions to the action of the masticatory organs. This vestibular buccal 
 cavity is provided with labial and buccal salivary glands. It is also interesting to find 
 that the parotid glands, the largest of all the salivary glands, pour their secretion into 
 this cavity. 
 
 The Palatine Arch and the Gums. 
 The palatine arch, or the hard palate (a, fig, 140), constitutes the Tipper wall of the buc- 
 cal cavity. It has the form of a parabolic arch, bounded in front and on either side by 
 the teeth, and behind by the velum palati, into which it is continued without any dis- 
 tinct line of demarcation. Upon it we observe, in the median line, an antero-posterior 
 raphe, at the anterior extremity of which is a tubercle corresponding to the lower orifice 
 of the anterior palatine canal. This tubercle has been incorrectly stated by physiolo- 
 gists to be endowed with a peculiar sensibility ; on each side and in front there are trans- 
 verse ridges, more or less marked in different individuals, which represent the still more 
 highly-developed ridges, bars, or calcareous concretions, which render the surface of the 
 roof of the palate in some animals so rugged. Posteriorly, the roof of the palate is per- 
 fectly smooth. 
 
 Structure. — The constituent parts of the palatine arch are an osseous framework, a 
 fibro-mucous membrane, a layer of glands, with vessels and nerves. 
 
 The framework consists of the bony palate already described : it is thicker in front 
 than behind, and is held up in the middle by the sort of column formed by the vomer and 
 the perpendicular plate of the ethmoid, and behind and on each side by the vertical por- 
 tions of the palate bones, and by the pterygoid processes. We have already noticed the 
 asperities which it presents, and which appear to have no other object than to secure 
 the intimate adhesion of the fibro-mucous membrane to the bones. 
 
 The Palatine and Gingival Membrane. — This mucous membrane is remarkable for its 
 whitish colour ; for the thickness of its epithelium, especially in front ; for the thickness 
 and density of its chorion, which even approaches to that of the corresponding tissue in 
 the skin ; for its close adhesion to the bones, into which the chorion sends off well-mark- 
 ed fibro-cellular prolongations ; and, lastly, for the great number of orifices with which 
 it is perforated, especially behind. This excessive thickness of the palatine membrane, 
 however, is observed only anteriorly, and most particularly so behind the incisor teeth. 
 The Glandular Layer. — In the median line the palatine membrane is blended with the 
 periosteum of the bones, but on each side it is separated from it by a very thick layer of 
 glands, which are sometimes arranged in regular rows along the antero-posterior groove 
 presented by the palatine arch. These palatine salivary glands are exactly similar to the 
 labial and buccal glands already described ; they are much more numerous behind than 
 in front, and open upon the membrane by a number of orifices visible to the naked eye. 
 There are often two openings mud more distinctly marked than the rest, situated one 
 on either side of the posterior extiemity of the median raphe. 
 
 The Gums. — The description of the peculiar tissue of the gums, to which some allusion 
 has been made in speaking of the teeth, naturally follows that of the palatine membrane. 
 The term gums {ovXa) is applied to those portions of the buccal mucous membrane which 
 surround the teeth. They are distinguished from the rest of that membrane by their 
 intimate adhesion to the periosteum, by their thickness, and especially by their almost 
 cartilaginous density, which enables them to resist the shocks of hard bodies during mas- 
 tication. In this latter respect, and in regard to their want of sensibility, the gums 
 closely resemble the contiguous portions of the palatine membrane. They commence 
 about a line from the base of the alveoli, their limits being marked by a scalloped ridge. 
 Having reached the free margins, i. e., the base of the alveoli, the gums continue their 
 course for the space of about a line beyond that point, as far as the neck of the teeth, 
 where they become reflected upon themselves. The point of reflection is a free border 
 of a semilunar shape, corresponding to the indented, and, as it were, festooned border 
 of each alveolus. The denticulations or longest portions of the gums correspond to the 
 intervals between the teeth, in which situation the processes of the gum, covering the 
 anterior and posterior surfaces of the alveoli, communicate with each other. 
 
 The reflected portion of the gum, though not adhering to, is in contact with, all that 
 portion of the root of the tooth which projects above the alveolus ; it then dips into the 
 cavity of the latter, so as to form the alveola-dental periosteum, which, as we have already 
 seen, is a powerful means of connecting the fang of the tooth to its socket. The tissue 
 of the gums appears to be provided with particular follicles for the secretion of the tar- 
 tar.* It varies much in different individuals, both in colour and in density. One of its 
 most peculiar characters is the singular effect produced on it by scurvy and by mercury, 
 under the influence of which agents it becomes softened and fungous, easily bleeds, and 
 furnishes a large quantity of tartar.* Another, but purely anatomical character, conbists 
 •'n its largely-developed openings or pores, which, in a particular light, an even vii^ible 
 
 * [These are nuutMis follicles : the tartar is now known to be merely a deposite from the saliva ; its inert ascc 
 amount during- 1..1 i\t.ri:il salivation is, therefore, readily accounted tor.l 
 
 Tt 
 
3iro SPLANCHNOLOGY. 
 
 to the naked eye. The gums are almost insensible when divided by cutting instruments ; 
 but the pressure exerted upon them by the teeth, during the eruption of the latter, often 
 gives rise to the most serious affections. 
 
 Vessels and Nerves of the Roof of the Palate and the Gums. — The arteries arise, seme 
 from the internal maxillary, viz., the posterior palatine, the alveolar, the infra-orbital, 
 and the mental branches ; others from the facial, viz., the superior coronary for the 
 gums of the upper, and the sub-mental branches for those of the lower jaw ; the sub-lingual 
 artery also supplies the latter. The veins bear the same name. All the nerves proceed 
 from the fifth pair, viz., the palatine and the superior and inferior dental branches. The 
 naso-palatine nerve sends ramifications to the small median tubercle upon the roof of 
 the palate. Few parts have so little cellular tissue as the gums. 
 
 Development. — According to the best authorities, the bony and membranous portions 
 of the hard palate are developed from two lateral points, which unite along the me- 
 dian line, so that the malformation known by the name of harelip with cleft palate, is 
 said to be an arrest of development. The fissure may be either single or double in front. 
 If the cleft be double, that portion of the upper jaw which supports the incisor teeth is 
 separated on both sides from the rest of the bone. Such divisions always seem to me 
 to be absolutely departures from nature,* for at no period of its growth can such separa- 
 tions or clefts be detected in a naturally-formed foetus. 
 
 Uses of the Gums and Hard Palate. — The hard palate separates the buccal cavity from 
 the nasal fossa. It serves as a fulcrum for the tongue in the act of tasting, in mastica- 
 tio'n, deglutition, and the articulation of sounds. Before the eruption of the teeth, the 
 gums completely close the alveoli, and serve as the immediate instruments of mastication ; 
 and they become hard, and supply the place of the teeth after the loss of those organs. 
 The gums have great influence in fixing the teeth within their sockets, and hence the 
 loosening of the former from scurvy or from the abuse of mercury. We may consider the 
 gums as that portion of the mucous membrane in which the dental follicles are situated. 
 
 The Velum Palati and Isthmus Faucium. 
 
 Dissection. — The lower surface of the velum palati may be seen by forcibly depressing 
 the lower jaw, or still better by sawing it across in the median line, and separating the 
 two halves. In order to see its upper surface, the pharynx must be removed entire, and 
 its posterior wall divided vertically (as in_^^. 141). The dissection of the different lay- 
 ers which enter into the formation of the velum palati, and of its extrinsic and intrinsic 
 muscles, will be understood from the following descriptions : 
 
 External Conformation. — The velum palati, or soft palate (c, fig. 140), is a muscular and 
 membranous valve, which prolongs the palatine arch backward, and, therefore, might be 
 called the membranous palatine arch. It is a sort of incomplete septum (septum staphylin, 
 Chauss.), dividing the buccal cavity from the nasal fossae and the pharynx. 
 
 Its direction is curved : its upper portion is horizontal, but it soon becomes curved, 
 and passes almost directly downward (velum pendulum palati). In the act of degluti- 
 tion, the velum becomes horizontal during the passage of the alimentary mass, but im- 
 mediately afterward returns to its oblique and pendulous position, and thus tends to pre- 
 vent the return of the food into the mouth. In several pathological conditions the velum 
 is thrown backward and upward, and adheres to the posterior orifices of the nasal fossae. 
 AH these changes of direction affect the oblique, and not the horizontal portion of the 
 velum. The velum palati is broad, quadrilateral, and perfectly symmetrical. Its in- 
 ferior or buccal surface is concave, and continuous with the hard palate, without any line 
 of demarcation. This surface is very well seen when the mouth is opened, and is, there- 
 fore, easily accessible to the surgeon. In the median line it presents a white raphe, 
 which is a continuation of the median raphe of the hard palate ; it is formed by a small 
 fibrous cord, causing a projection under the mucous membrane. 
 
 The superior or nasal surface of the velum {fig. 141) is convex : it prolongs the floor 
 of the nasal fossae, and, from its obliquity, directs the mucus into the pharynx. This 
 surface presents a median projection produced above by the palato-staphylin muscles 
 (azygos uvulse, a), and below by a mass of glands. Congenital division of the velum is 
 always situated in the median line, and is followed by so great a retraction of its two 
 halves, that, in some cases, the entire absence of the velum has been suspected. 
 
 Its upper border is thick, and firmly united to the posterior border of the hard palate. 
 
 Its lower border is free, extremely thin and concave, and forms the upper boundary of 
 the isthmus {t,fig. 141) of the fauces : it presents, in the middle line, a sort of appendix 
 or prolongation, called the uvula (u,fig. 140) : this is of a conical shape, and of very va- 
 riable size and length ; it is capable of considerable elongation, and may then reach the 
 base of the tongue, but not, as has been supposed, the upper orifice of the larynx.t It 
 is not very uncommon to find it bifid, and sometimes it is entirely wanting. 
 
 * [/. c, not mere arrests of development.] 
 
 + In consultation upon a case of chronic laryngitis, I was much surprised to hear the medical attendant 
 state that the disease was the result of irritation produced by the UTula upon the superior orifice of the 1* 
 rfnx. The position of the uvula is always a few lines in advance of the epiglottis. 
 
THE VELUM PALATI. 331 
 
 The two lateral borders of the velum limit it on each side, and separate it from the 
 cheek. This boundary is indicated (on each side) by a prominent ridge (before /, fi^. 
 140), extending from the posterior extremity of the upper to the corresponding part of 
 the lower alveolar border. This prominence corresponds to the anterior margin of the 
 internal pterygoid muscle, and is formed, in a great measure, by a series of small, glan- 
 dular structures, which are collected behind the last great molar tooth of the lower jaw 
 into a considerable mass resembling a small gland. 
 
 The pillars of the velum palati. These are two lateral columns or pillars, having an 
 arched form, and distinguished into anteriw (behind /, fig. 140) and posterior {g), which 
 pass down on either side from the uvula. Each of the anterior pillars (the two forming 
 together the anterior arch of the fauces) proceeds from the base of the uvula outward, 
 and then vertically downward, describing a curve with its concavity directed inward, 
 and terminates at the sides of the tongue, opposite the anterior extremities of the V- 
 shaped series of papillae vallatae found upon that organ. Each of the posterior pillars 
 (which together form the posterior arch of the fauces) commences at the apex of the 
 uvula, and immediately curves into an arch, having a smaller diameter than that repre- 
 sented by the anterior pillar, and then passes obliquely downward, backward, and out- 
 ward, to its termination on the sides of the pharynx. The two posterior pillars consti- 
 tute the free margin of the velum. They project much farther inward than the anterior 
 pillars, so that when the base of the tongue is depressed in the living subject, both sets 
 of pillars can be seen at the same time, like double curtains, placed on different planes. 
 Each of these pillars represents a triangle, having its base below and its apex above. 
 
 ITie Amygdaloid Fossa. — From the direction of the anterior and posterior pillars, they 
 approach each other above, and are separated by a considerable interval below. This 
 interval, which is partly occupied by the tonsil (w), may be called the amygdaloid excava- 
 tion. In order to have a good idea of it, it is necessary to make a vertical section of the 
 head from before backward. A sort of recess will then be observed, narrow and shallow 
 above, but very broad and deep below, especially when the tonsil (n) is small. The base 
 of this fossa corresponds anteriorly to the base of the tongue (J), then to the epiglottis 
 (i), the larynx, and the walls of the pharynx : the bottom of the fossa corresponds to the 
 angle of the lower jaw and the lateral portion of the supra-hyoid region, where it is sep- 
 arated from the skin only by a thin layer of soft tissues. The dimensions of this fossa 
 always remain the same above, but are very variable below, according as the tongue is 
 retained in the mouth or protruded. 
 
 The Isthmus Faucium. — The posterior orifice of the buccal cavity is called the isthmus 
 faucium (2, figs. 140, 141). It is a sort of passage between the buccal and the pharyn- 
 geal cavities, bounded below by the base of the tongue, above by the free margin of the 
 velum palati, divided into two arches by the uvula in the middle, and the two pillars on 
 each side. This posterior orifice of the mouth, though very dilatable, is less so than the an- 
 terior opening of the same cavity. It may be contracted, and even completely closed, not 
 only from inflammation of the tonsils and arches of the fauces, but also from the contraction 
 of the muscles which enter into the formation of the velum and its pillars. This may be 
 seen by watching the movements of the isthmus of the fauces in a person who will sub- 
 mit to such an examination. These differences in the dimensions of the isthmus are con- 
 cerned not only in deglutition, but also in the modulations or articulations of the voice. 
 
 Structure. — In the velum palati we find an aponeurotic framework ; also certain mus- 
 cles by which it is moved, which are either extrinsic or intrinsic. The intrinsic mus- 
 cles are those constituting the azygos uvulae, viz., the palato-staphylini ; and the extrin- 
 sic muscles are four on each side, two descending, viz., the levator palati, and the cir- 
 ciunflexus or tensor palati, and two ascending, viz., the palato-glossus, and the palato- 
 pharyngeus. We also find in the soft palate a thick layer of glands, vessels, nerves, and 
 cellular tissue ; and, lastly, a covering of mucous membrane. 
 
 The Aponeurotic Portion. — The aponeurotic portion, or, rather, the principal aponeuro- 
 sis, is extremely dense, and continues the hard palate backward : it is generally regarded 
 as an expansion of the reflected tendons of the tensores palati, but it is, in a great measure, 
 formed of proper fibres continuous with the fibrous tissue, which prolongs backward the 
 septum narium, the outer borders of the posterior orifices of the nasal fossae, and the 
 fibrous portion of the Eustachian tube. Below this aponeurotic membrane there is an- 
 other fibrous lamella, continuous with the fibrous tissue found in the hard palate. The 
 framework of the upper half of the velum palati may, therefore, be said to be formed of 
 two fibrous layers, one superior, the other inferior, between which the glandular layer is 
 situated. Lastly, a small fibrous band extends from the nasal spine to the uvula, along 
 the median raphe, upon the lower surface of the velum, producing a slight elevation of 
 the mucous membrane. This little band sends off a prolongation between the glands of 
 the velum, which separates the right half of the soft palate from the left. 
 
 The Muscles of the Velum Palati. 
 Dissection. — This is common to all the muscles of the soft palate. It is merely neces- 
 sary to remove the mucous membranes and the subjacent glands, in order to study the 
 
SPLANCHNOLOGY. 
 
 arrangement of these muscles, and to follow the ascending and descending fibres which 
 emerge from or enter into the velum. 
 
 The Azygos Uvidcs, or Palato-staphylini. 
 The palato-staphylini (a, fig. 141) are two small, fleshy, cylindrical bands placed in 
 Fig. 14L contact, one on each side of the median line, and extending 
 
 from the posterior nasal spine, or, rather, from the aponeuro- 
 sis continuous with it, to the base of the uvula. They are 
 covered by the mucous membrane of the nose, under which 
 they form a projection, and they cover the levatores palati. 
 The two muscles, from their juxtaposition, appear, at first 
 sight, to form a single rounded muscle, to which the names 
 azygos uvulcz, columellcB musculus teres, have been given. 
 Action. — To raise the uvula. 
 
 The Levator Palati, or Peristaphylinus Internus. 
 
 Dissection. — Remove the mucous membrane from a verti- 
 cal ridge which exists along the outer border of the posterior 
 orifice of one of the nasal fossae, behind the Eustachian tube ; 
 then remove the mucous membrane covering the upper sur- 
 face of the soft palate. 
 
 The vertical portion of the levator palati (le petro-salpin- 
 go staphylin, Winslow ; petro-staphylin, Chauss., c,figs. 141, 
 146) is situated upon the outer side of the posterior orifice of the corresponding nasal 
 fossa ; its horizontal portion is in the substance of the velum ; it is thick, narrow, and 
 rounded above, expanded and triangular below. It arises by short tendinous fibres from 
 the lower surface of the petrous portion of the temporal bone, near its apex, and from 
 the contiguous part of the cartilage of the Eustachian tube. From these points its fibres 
 pass obliquely downward and inward, turning round the outer side of the tube. At the 
 outer border of the velum palati the muscle becomes horizontal, and its fasciculated fibres 
 diverge, so as to cover the whole extent of the antero-posterior diameter of the velum. 
 
 The anterior fleshy fasciculi are inserted by short tendinous fibres into the posterior 
 border of the aponeurosis of the soft palate. The others also terminate by very short 
 tendinous fibres, which are blended in the median line with those of the opposite side, 
 immediately below the azygos uvulae. 
 
 Relations. — It is covered by the mucous membrane of the pharynx and soft palate ; its 
 vertical portion is in relation, on the outside, with the circumflexus palati and the supe- 
 rior constrictor muscles, and its horizontal portion with the palato-pharyngeus. It forms 
 the uppermost muscular layer of the soft palate. 
 
 Action. — It raises the velum (elevator palati mollis, Albin., Samm.). The length of its 
 fibres, its direction, and its shape, render it well fitted for this purpose. It should be re- 
 marked, that the tendinous portion of the velum scarcely participates in the movement 
 of elevation. 
 
 The Circumflexus or Tensor Palati, or the Peristaphylinus Externus. 
 
 This is a thin, flat, and reflected muscle (le pterygo or spheno salpingo staphylin, 
 Winsl. ; pterygo-staphylin, Chauss.), and is tendinous for a considerable part of its ex- 
 tent ; its vertical portion {d, fig. 141, 146) is situated* along the internal plate of the ptery- 
 goid process, to the inner side of the internal pterygoid muscle (b), and its horizontal 
 portion {d) in the substance of the velum. 
 
 Attachments. — It arises from the fossa navicularis, at the base of the internal pterygoid 
 plate, from the contiguous part of the great wing of the sphenoid, and from a small por- 
 tion of the cartilage of the Eustachian tube. From these points the muscle, which forms 
 a thin fasciculus, flattened at the side, passes vertically downward : near the hamular 
 process of the internal pterygoid plate it becomes a shining tendon, which changes its 
 direction, and is reflected at a right angle under that process : it is retained in this situ- 
 ation by a small ligament, and its motions are facilitated by a synovial membrane. The 
 tendon then passes horizontally inward, expands, and becomes blended with the aponeu- 
 rotic membrane. 
 
 Relations. — Its vertical portion is in relation on the outside with the internal pterygoid, 
 and on the inside with the levator palati, from which it is separated by the superior con- 
 strictor of the pharynx (g,fig. 141) and by the internal pterygoid plate. Its horizontal 
 or aponeurotic portion is anterior to the levator palati, and has the same relation as thp 
 aponeurotic portion of the velum. 
 
 Action. — It is a tensor of the aponeurotic portion (tensor palati), but does not otherwise 
 move the velum. As Haller has remarked, when its fixed point is below, it can dilate 
 the Eustachian tube. 
 
 The Palato-pharyngeus, or Pharyngo-staphylinus. 
 This muscle (thyro-staphylinus, Douglas, e e,fig. 141) is narrow and fasciculated in the 
 
THE PALATO-GLOSSUa. 333 
 
 middle, where it is situated in the posterior pillar of the fauces, broad and membranous 
 at its extremities, one of which is in the velum and the other in the pharynx. 
 
 Attachments. — It arises from the whole extent of the posterior border of the thyroid 
 cartilage. From this point it passes vertically upward, and forms a broad and thin mus- 
 cular layer, the fibres of which are first collected into a fasciculus or muscular column, 
 which enters the posterior pillar of the fauces, and then, again expanding, ocaipy the 
 whole extent of the antero-posterior diameter of the velum, and unite in the median line 
 with the muscle of the opposite side, so as to form an arch. The anterior fibres are in- 
 serted into the posterior border of the aponeurosis of the velum. 
 
 RclatioTis. — It forms the lowest muscular stratum of the velum : it is separated from 
 the mucous membrane below by the layer of glands : it is in relation above with the 
 muscular layer formed by the expansion of the levator palati. In the posterior pillar it 
 is in relation with the mucous membrane, which covers it in all directions, excepting on 
 the outside. In the pharynx it forms the innermost muscular layer, i. c., it lies between 
 the constrictors and the mucous membrane. 
 
 Action. — The two palato-pharyngei draw the velum downward, and press it strongly 
 against the alimentary mass during deglutition ; they therefore form a constrictor of the 
 isthmus of the fauces. When they take their fixed points above, they raise the poste- 
 rior wall of the pharynx. They are important agents in deglutition. 
 
 The Palato-glossus, or Olosso-staphylinus. 
 
 This is a small fleshy bundle {o,jig. 141) situated in the anterior pillar of the fauces, 
 narrow in the middle, and broad at the extremities. Its lower extremity is expanded 
 upon the side of the tongue, and is united with the stylo-glossus. Its upper extremity 
 spreads out in the velum palati, and becomes blended with that of the palato-pharyngeus. 
 Its middle portion is very slender ; it forms the anterior pillar, and is visible through the 
 thin mucous membrane by which it is covered. 
 
 Action. — The two muscles depress the velum palati, and raise the edges of the base 
 of the tongue ; they consequently constrict the isthmus faucium. 
 
 The Glandular Layer of the Velum Palati. — Under the mucous membrane covering the 
 upper surface of the velum palati, there are some scattered glands, M'hich are more nu- 
 merous on the sides than along the middle ; but on the lower surface of the velum there 
 is a much more obvious collection of glands, particularly dense, opposite the aponeurotic 
 portion of the velum, and forming a contiouation of the glandular layer of the hard pal- 
 ate. Similar glands are found in the uvula, the size, and, in some measure, the form of 
 which they determine. These small glands in the velum exactly resemble the salivary 
 glands already described as existing in the lips, the cheeks, and the roof of the palate. 
 
 The Mucous Membrane. — Both surfaces of the velum are covered by mucous mem- 
 brane, which constitutes, as it were, its integuments. These two mucous layers are 
 remarkable, inasmuch as each presents the peculiar characters of the cavity to which it 
 belongs. Thus, the lower layer preserves the characters of the buccal mucous mem- 
 brane, and the upper layer those of the nasal.* The two layers are continuous with 
 each other along the free margin of the velum palati ; the fold of mucous membrane 
 forming this margin passes beyond' the other constituent tissues, so that, for the space 
 of half a line or a hne, the two mucous layers are in contact. The same occurs in the 
 uvula, the apex, and sometimes the lower half of which consists of a duplicature of mu- 
 cous membrane, containing some loose cellular tissue, which is very susceptible of infil- 
 tration. Either serous or sanguineous infiltration of the uvula produces an elongation of 
 this part, called relaxation of the uvula. I should not omit to mention the great differ- 
 ence, in regard to sensibility and liability to inflammation, that exists between the mu- 
 cous membrane of the free and adherent borders of the velum palati. 
 
 Vessels and Nerves. — These are very numerous in proportion to the size of the part. 
 The arteries arise from the palatine and the superior and in/erior pharyngeal. The veins 
 are similarly named, and follow the same course. The lymphatic vessels, which have 
 been little studied, enter the lymphatic glands at the angle of the jaw. The nerves are 
 derived from the palatine branches given off by Meckel's ganglion, and from the glosso 
 pharyngeus. 
 
 Development. — ^We have here again the question, whether the velum is formed origi- 
 nally from two halves, which afterward become united in the median line ; in favour of 
 this view we may adduce those cases in which the uvula and the velum are bifid, either 
 with or without fissure of the hard palate and lip. In the youngest embryos which I 
 have examined, I have always found the velum undivided. 
 
 Uses. — The velum palati is a contractile valve, which fulfils very important functions 
 in deglutition, in the utterance of articulate sounds, and in the modulation of the voice ; 
 it is capable of being elevated and depressed Elevation affects its muscular, but not its 
 
 * [According to the recent researches of Dr. IIenl6, the ciliated cohimnar epithelium (like that of the nasal 
 mucous membrane) is found upon the upper surface of the velum, only in the neighbourhood of, and a short 
 distance below, the expanded orifice of the Eustachian tube ; the remaininsr portion of the upper surface, as 
 well as the free border, and the whole of the lower surface, are covered with the squamous epithelium, simi 
 lar to that of the buccal mucous membrane.] 
 
334 SPLANCHNOLOGY. 
 
 aponeurotic portion : this movement cannot be carried so far as to revert the velum up- 
 ward. Depression may be carried to such an extent as to close the isthmus faucium by 
 the approximation of the velum and the base of the tongue. The contraction of the pa- 
 lato-pharyngei, which are curved muscles, may be so complete as to bring the posterior 
 pillars of the fauces into contact, and thus close the isthmus in a transverse direction. 
 The uvula moves independently of the velum. When the aponeurosis of the velum pa- 
 lati is rendered tense, the velum itself is enabled to resist both elevation and depression. 
 
 The Tonsils, or Amygdal.*:. 
 
 The terms amygdala. (ufivySaMa, an almond), or tonsils, are applied to a group of mu- 
 cous follicles (n, fig. 140) which occupy the interval between the pillars of the fauces on 
 each side. They are placed there on account of the necessity of lubricating the isthmus 
 during the passage of the alimentary mass. Their form pretty nearly resembles that of 
 an almond ; they are directed obliquely downward and forward, and their size is exceed- 
 ingly subject to either congenital or accidental variation. In some subjects they can 
 scarcely be said to exist ; in others they fill up the whole amygdaloid fossa, and project 
 more or less into the isthmus of the fauces, so as to impede deglutition, o^ fcv^en respiration. 
 
 The compound tonsil results from its component follicles being collected into several 
 distinct masses. 
 
 The internal surface is free, and may be seen when the base of the tongue is depress- 
 ed ; it is perforated by foramina, like the ligneous shell of an almond. These foramina, 
 which vary in number and size, have been frequently mistaken for syphilitic ulcerations. 
 They lead into small cells, in which mucus sometimes collects, and is then ejected in 
 hard fetid lumps, which have been erroneously supposed to be pulmonary tubercles. Its 
 external surface is covered immediately by the aponeurosis of the pharynx,* and then by 
 the superior constrictor. 
 
 The tonsil corresponds to the angle of the lower jaw. Compression behind this an- 
 gle, therefore, affects it at once, and causes pain in cases where it is inflamed. It has an 
 important relation with the internal carotid artery, especially when that vessel, descri- 
 bing a curve with the convexity directed inward, touches the tonsil. In front the tonsil 
 is in relation with the anterior pillar of the fauces, and, therefore, with the palato-glossus 
 muscle ; behind, with the posterior pillar, and, accordingly, with the palato-pharyngeus 
 muscle. 
 
 Structure. — In structure the tonsils are intermediate between mucous follicles and 
 glands ; they consist of an agglomeration of follicles, continuous with those at the base 
 ot the tongue. Groups of these follicles open into small cells or lacunae, which again 
 open upon the internal surface of the tonsil by the foramina already described. The 
 mucous membrane covers the inner surface of the tonsil, and, penetrating through the 
 foramina, lines the interior of all the cells. 
 
 The arteries are very large, considering the size of the organ. They are derived from 
 the labial, the inferior pharyngeal, the lingual, and the superior and inferior palatine. 
 The veins form a plexus round this organ, called the tonsillar plexus ; it is a dependance 
 of the pharyngeal plexus. The lymphatic vessels terminate in the glands found near the 
 angle of the jaw ; hence the inflammation or enlargement of those glands in conse- 
 quence of inflammation of the tonsil. The lingual and glosso-pharyngeal nerves form a 
 plexus outside the tonsil, which gives off some branches to it. 
 
 The Tongue. 
 
 The tongue, the principal organ of taste, is situated within the buccal cavity, and, con- 
 sequently, at the commencement of the digestive passages (J, fig. 140) behind the lips, 
 which in many animals are organs of prehension ; also behind the teeth, the organs of 
 mastication, and below the organ of smell, which possesses the sense of taste in the 
 lower tribes, and is necessary in all animals for the perception of flavours. It is a mus- 
 cular organ, free and movable above, before, and on the sides. It is retained in its po- 
 sition by ligaments which attach it to the os hyoides ; and, by muscles connecting it to 
 the same bone, to the styloid processes and to the lower jaw ; so that it appears to me 
 anatomically impossible for persons to have been destroyed by swallowing their tongues, 
 as some historians have related. Nor do I believe, notwithstanding the authority of J 
 L. Petit, that division of the fraenum in infants may be followed by a similar accident. 
 
 The size of the tongue, though variable in different individuals, is always proportional 
 to the curve described by the lower jaw ; it is not large enough to fill the buccal cavity 
 completely when the jaws are closed. It has not been satisfactorily proved that too 
 large a tongue is the cause of certain defects in speech. However, a natural size is not 
 absolutely necessary for the exercise of its functions, for these are performed even when 
 considerable portions have been removed from its apex and sides. 
 
 Direction. — Its anterior portion is horizorttal ; behind, it slopes downward and back- 
 ward, and curves abruptly, so as to become vertical and reach the os hyoides, which in 
 some measure constitutes its base. This direction, which is maintained so long as the 
 
 ♦ The existence of this aponeurosis explains why the tonsil always becomes enlarged internally, and also 
 why abscesses of this part never open externally. 
 
THE TONGUE. 
 
 335 
 
 tongue is within the mouth, is somewhat altered when it is protruded, the tongue then 
 becoming horizontal, and the os hyoides raised. 
 
 Figure. — Examined without any anatomical preparation, the tongue appears of an oval 
 figure, having its great end behind. Its form is determined, and, as it were, measured, 
 by the parabolic curve of the lower jaw, by which it is circumscribed. When separated 
 from the neighbouring parts, it represents an ellipse, with its long diameter from before 
 backward. It is perfectly symmetrical, flattened above and below, narrow and thin in 
 front, and increasing in thickness and in breadth from before backward. Its figure, 
 which has itself become a term of comparison, does not appear to be essential for the 
 articulation of sounds, a function that would at first appear to be peculiarly connected 
 with this form. 
 
 The tongue presents for our consideration an upper and a 
 lower surface, two edges, a base, and an apex. 
 
 The Upper Surface or Dorsum of the Tongue. — This is free 
 in the whole of its extent, corresponds to the roof of the pal- 
 ate, and is divided into two lateral halves by a median furrow, 
 which often limits the progress of disease. It is covered by 
 innumerable eminences, which render it very rough ; these 
 should be distinguished into such as are perforated, viz., the 
 glandular eminences, and such as are entire, and have no ori- 
 fice, viz., the papilla {papilla, a nipple). 
 
 The perforated eminences, or lingual glands, improperly class- 
 ed among the papillae, and known under different names,, may 
 be distinguished by their circular openings, which are perfect- ,| 
 ly visible to the naked eye ; by their being situated only at the 
 base of the tongue ; by their rounded form, and their having 
 no pedicle ; by the arrangement of the mucous membrane, 
 which passes over without adhering to them ;* and, lastly, by 
 dissection, which most distinctly reveals their glandular na- 
 ture. These lingual glands, moreover, are not follicles, but 
 true glandular organs, analogous to the labial and buccal 
 glands. They form a V-shaped ridge, strongly marked in 
 some subjects, and bounded in front by the ridge (a a, fig. 
 142) of the same shape, formed by the caliciform papillae. 
 
 All the other eminences of the tongue are papillae, which we may describe as the large 
 and the small. 
 
 The large papillce are called caliciform : they are arranged in two lines (a a, fig. 142), 
 united like the limbs of a V, open in front. Their number varies from sixteen to twen- 
 ty, some of which are placed irregularly. Haller has seen them forming two rows on 
 each side. Their size is also variable, but they are larger than all the other papillae. 
 Each papilla forms a truncated and inverted cone, the base of which is free, and the 
 truncated apex adherent (papillae truncate, Haller ; papilles boutonnees ou a tete, Boyer). 
 They are placed in a sort of calyx or cup, or surrounded by a circular trench : hence the 
 name of papillae circumvallatae (papilles cahciformes, Cuvier). The border or rim of this 
 cup is itself a circular papilla, t 
 
 At the angle of union of the two rows of these glands is a blind opening (b), which is 
 frequently wanting, and generally known as the foramen caecum of Morgagni (lacune de 
 la langue, Chaussier). Several anatomists of the last century affirmed that certain sup- 
 posed salivary ducts, which were afterward shown to be merely veins, had their termi- 
 nation in this foramen ; it is now generally considered to be a cul-de-sac for the recep- 
 tion of the secretion from several follicles ; but it appears to me to be only the cavity 
 of a calyx, the papilla corresponding to which is very imperfectly developed. When the 
 papilla is more developed, or the calyx less deep than usual, the foramen caecum is said 
 to be wanting. 
 
 The Smull Papilla. — These occupy all that part of the dorsal surface of the tongue 
 which is in front of the V-shaped ridge, formed by the papilla circumvallatae ; they pre- 
 sent many varieties. Some of them are conical, others filiform ; some are pointed like 
 a reed, and others are lenticular or fungiform, that is, flattened at the top, and supported 
 by a narrow pedicle ; but the conical or filiform are evidently the most numerous, for 
 they occupy of themselves the anterior portion and the apex of the tongue, while all the 
 other varieties are disseminated between them. They are directed obliquely backward, 
 
 * ll. e., without being closely united to their outer surface, as it is to that of the papillse. The mucous 
 membrane, as in all glands, is really prolonged into their interior.] 
 
 t The want of a uniform nomenclature for the papilla: of the tongue has occasioned great obscurity. I do 
 not know two authors who agree in this respect. M. Boyer calls the lingual glands papilles lenticulaires ; the 
 caliciform papillse, papilles boutonnees ou a tile ; and applies the term papilles coniques to the papillse generally 
 known by that name. Gavard called the glands papilles muqueuses ; and the caliciform p.ipillffl, papilles fungi- 
 formes. M. H. Cloquet appears to have confounded both the glands and the caliciform papilla; under the name 
 of papilles lenticulaires ; the papilles fungiformes, according to him, are irregularly disseminated over the edges 
 and apex cfthe tongue. The use cif tile tenn conical papillse is the only point in which they are all agreed. 
 
 4 
 
SPLANCHNOLOGY. 
 
 SO that, by rubbing the tongue sUghtly from behind forward, they may be brushed up, 
 and their exact sliape and length ascertained. This oblique direction is much more 
 marked in the lower animals than in man. 
 
 The conical papillae are sometimes arranged in regular or irregular lines, so as to give 
 the tongue a fissured appearance. Sometimes even several papillae are united in a line, 
 so as to form a jagged ridge. We may add, that there is very great variety both in the 
 shape and arrangement of the lingual papillae.* 
 
 The lower surface of the tongue is free only in its anterior third, the muscles which con- 
 nect the tongue to the neighbouring parts being attached to the posterior two thirds. On 
 the free portion, which we shall alone notice here, is observed a median furrow, more 
 distinct than that on the upper surface. At the posterior part of this furrow is a fold of 
 mucous membrane, called the franum lingua, which is sometimes prolonged to the apex 
 of the tongue, and prevents the movements of that organ, both in the act of sucking and 
 during articulation : hence the necessity for the operation known as the division of the 
 fracnum. On each side of this furrow are seen the ranine veins, on which the ancients 
 performed venesection ; also an antero-posterior projection formed by the lingual muscle. 
 
 The edges of the tongue are thick behind and thinner towards the point. The papiUae 
 are prolonged in a regular manner upon their upper half in a series of vertical and par- 
 allel lines. 
 
 The actual base is fixed to the os hyoides : the apparent base, which is seen at the 
 back of the dorsal surface, presents three glosso-epiglottid folds, of which the median 
 (above b,fig. 142) is much larger than the other two. 
 
 The apex is situated immediately behind the incisor teeth ; the median furrows of both 
 surfaces are prolonged upon it. 
 
 Having thus examined the peculiarities offered by the external surface of the tongue 
 without the aid of dissection, we shall now examine its structure. 
 
 Structure of the Tongue. — The tongue being the organ of one of the senses, and being, 
 also, capable of various movements, we must examine its structure with reference to 
 both these objects. But, after the example of Haller,+ we shall be principally occupied 
 here with its structure as a movable organ. 
 
 The tongue is essentially composed of muscular fibres, and, in this respect, the heart 
 is the only organ which can be compared to it. Its framework consists of the os hy- 
 oides, of a median cartilaginous lamina, and of its papillary membrane. 
 
 Framework of the Tongue. — The os hyoides, already described (seen in^^. 143), is tru- 
 ly the bone of the tongue : hence it has been called the lingual bone by some anatomists. 
 In man it is not prolonged by a process into the substance of the tongue, as in the lower 
 animals, but is united to it by the hyo-glossal membrane, which commences at the pos- 
 terior lip of the body of this bone ; and, again, since the os hyoides is united to the thy- 
 roid cartilage {t) by ligaments, it follows that all the movements of this bone are commu- 
 nicated both to the tongue and to the larynx, between which parts it is situated. From 
 the middle of this fibrous membrane, the median cartilaginous lamina of the tongue, de- 
 scribed by M. Blandin, proceeds. This lamina, which is perfectly distinct from the car- 
 tilage described by M. JBaur in the dog and the wolf,t is situated in the median line ; it 
 is directed vertically, and gives attachment to some muscular fibres by its two lateral 
 surfaces ; its upper edge is thin, and reaches the middle of the dorsal region of the tongue , 
 its lower edge is seen between the genio-hyo-glossi, where it is either free or covered 
 by a few muscular fibres which interlace below it. It is thick behind, but thin in front, 
 where its fibres have a number of intervals between them, like those in the septum of 
 the corpora cavernosa penis. 
 
 I regard the papillary membrane as part of the framework of the tongue, on account of 
 Its density, which is so great that it is with difficulty cut by the scalpel. Moreover, a 
 great number of the muscular fibres terminate in it. 
 
 The Muscles of the Tongue. 
 
 These are either intrinsic or extrinsic. 
 
 The Intrinsic Muscles. — The ancients regarded the tongue as a single muscle, t*" 
 structure of which they did not attempt to unravel. Columbus was the first to conside? 
 this organ as composed of two juxtaposed muscles. If the texture of the tongue be ex- 
 amined by means of sections made in different directions, it will be found to be compo- 
 sed of an interlacement of muscular fibres, which will, indeed, appear to be inextricable. 
 Among these different sections, I would principally call attention to a vertical section, 
 made at right angles to the axis of the tongue. This section presents a pale muscular 
 
 * [All these kinds of papillae are extensions of the mucous membrane, and are, therefore, composed of simi- 
 lar elements. The papillae vallatae contain many loops of vessels, the papillae conicae, in general, only a few ; 
 all are abundantly supplied with nerves.] 
 
 t Hallcr treats of the muscles of the tongue when describing the organ of voice (lib. ix., sect, ii., p. 421), 
 and of the papillary membrane with the organs of the senses (lib. xiii., sect. )., p. 99). 
 
 t Ihe cartilage described by Baur is a fibrous cord, subjacent to the mucous membrane, and occnpying the 
 median line on the lower surface of the tongue. It extends from the apex of the latter, where it is very wel 
 marked, to \Ui: l^ise. where it terminates in a cellular rapht. 
 
THE MUSCLES OF THE TONGUE. 337 
 
 tissue in the centre, in which successive layers of vertical and transverse fibres may be 
 distinguished. A soft, fatty substance, the lingual adipose tissue, is interposed between 
 these muscular fibres ; it is analogous to the fat formed at the base, or, sometimes, among 
 the fibres of the ventricles of the heart ; it increases in quantity towards the base of the 
 tongue, but is entirely wanting at the apex. Around this central part of the tongue, 
 whicli may with propriety be called, after M. Baur, the lingual nucleus (noyau lingual), we 
 find a very thin layer of red fibres situated above, a somewhat thicker layer on each side, 
 and a much thicker layer below ; the lateral and inferior layers belong to the extrinsic 
 muscles. 
 
 A transverse vertical section, therefore, demonstrates the presence of vertical and trans- 
 verse fibres in the tongue : an antero-posterior vertical section shows that there are fibres 
 running from one end of the organ to the other, and will also display the vertical fibres 
 already mentioned. Thus, by means of simple sections, we can demonstrate the exist- 
 ence of longitudinal fibres running from the base to the apex of the tongue ; of vertical 
 fibres passing from the upper to the lower suarface ; and of transverse fibres extending 
 from one side to the other ; and other dissections will confirm this statement. Though 
 Malpighi,* in a memoir of great interest, had very exactly described and figured the ar- 
 rangement of the three orders of fibres in the tongue of the calf ; though Steven proved 
 their existence in the human tongue, and Bidloo had carried his observations still far- 
 ther ; and although Massa had recommended that, to facilitate this investigation, the 
 tongue should be previously boiled, or should be examined after putrefaction had com- 
 menced ; still, almost all anatomists, including Haller, neglected this subject, until MM. 
 Baur, Gerdy, and Blandin directed attention to it almost at the same time. From the 
 examination of the boiled tongues of the ox, the sheep, and man, I have observed the 
 following facts : 
 
 1. Under the papillary membrane, which, as I have said before, has almost the density 
 of cartilage, there is a series of fibres running from before backward. These fibres ap- 
 pear to rise in succession from the papiUary membrane, and form a layer, which is thicker 
 in front, where the fibres are collected into a small space, than it is behind, where they are 
 scattered and pale. In the ox they traverse the yellowish glandular-looking substance 
 found at the base of the tongue. This thin layer is described by Malpighi, and has been 
 called the superior or superficial lingualis muscle. 
 
 2. On the lower surface of the tongue, between the genio-hyo-glossus and the hyo- 
 glossus, we find a longitudinal bundle, reaching from the base to the apex. This thick 
 bundle was first described by Douglas under the name of the lingualis muscle ; it might be 
 called the inferior lingualis. The lingual muscle of authors generallyt is a small mus- 
 cular fasciculus, situated on the lower surface of the tongue, between the stylo-glossus 
 (m, fig. 143) and the genio-hyo-glossus (a). It arises from the base of the tongue, in an 
 indistinct manner, amid an intricate mass of muscular fibres ; from thence it passes for- 
 ward, and terminates at the apex of the tongue, where it unites with the fibres of the 
 stylo-glossus. It shortens the tongue, and depresses its point. 
 
 3. On either side of the tongue we find two layers of oblique and very thin fibres, cross- 
 ing each other. The superficial layer consists of fibres passing forward and downward, 
 the deep layer of fibres running obliquely forward and upward. These two layers can 
 only be seen towards the base. They are more easily shown in the ox than in man. 
 We also find along each side some antero-posterior fibres, continuous both with the stylo- 
 glossus and the palato-glossus. 
 
 4. Lastly, the dissection of the lingual nucleus of a boiled tongue enables us most dis- 
 tinctly to separate the vertical and transverse fibres already noticed as being seen in the 
 different sections of the tongue. The transverse fibres form a slight concavity above : 
 the vertical fibres converge a little from above downward. In the substance of the lin- 
 gual nucleus, near the base of the tongue, a soft, liquid, adipose Fig. 143. 
 matter is interposed between the muscular fibres. 
 
 The Extrinsic Muscles. — The extrinsic muscles are three on 
 each side, viz., the stylo-glossus, the hyo-glossus, and the genio- 
 hyo-glossus. 
 
 The Stylo-glossus. 
 The stylo-glossus {u,figs. 114, 143, 146) is a small, slender mus- 
 cle, cylindrical above, thin, triangular, and bifid below. It arises 
 from the styloid process by some tendinous fibres surrounding the 
 lower half of that process, and slightly also from the stylo-maxil- 
 lary ligament. The fleshy fibres proceeding from these points 
 form a rounded fasciculus, which passes downward, inward, and 
 forward. At the margin of the tongue, opposite the anterior pillar 
 of the fauces, the muscle becomes flattened, expanded, and trian- 
 
 * It is notunwoithy of notice, that Malpighi commenced upon the tongue that series of researches into the 
 structure of organs which has made him, as it were, the founder of textural anatomy. 
 
 t [From this statement Albinus must be excepted ; the lingualis of that anatomist corresponds exactly witb- 
 Sie muscle described by Douglas.] 
 
 Ua 
 
338 SPLANCHNOLOGY. 
 
 gular, and divides into two parts : one external, which runs along the corresponding 
 margin of the tongue, from the base to the apex ; the other internal, which passes be- 
 tween the two portions of the hyo-glossus, assumes a transverse direction, and is blend- 
 ed with the transverse fibres of the tongue. 
 
 Relations. — On the outside it is in relation, successively, with the parotid gland, the in- 
 ternal pterygoid muscle, the sub-lingual gland, the lingual branch of the fifth nerve, and 
 the mucous membrane of the tongue. On the inside it has relations with the stylo- 
 hyoid ligament, the tonsil, the superior constrictor of the pharynx, and the hyo-glossus 
 muscle. 
 
 Action. — ^The stylo-glossus draws the corresponding edge of the tongue, and, conse- 
 quently, the entire organ, upward, and to its own side. When the two stylo-glossi act 
 together, the tongue is increased in breadth, and carried upward and backward : it there- 
 fore assists in retraction of the tongue. 
 
 The Hyo-glossus. 
 
 This is a thin, quadrilateral muscle {t,figs. 113, 114, 146), arising from the os hyoides 
 by two very distinct origins : one from the body of the bone, near the great cornu ; the 
 other from the whole extent of the anterior border of the great cornu, and also from its 
 point. 
 
 From this double origin the fleshy fibres pass upward parallel to each other, forming 
 a quadrilateral muscle, which expands a little, in order to terminate upon the sides of the 
 tongue, between the stylo-glossus and the lingualis. There is an evident continuity be- 
 tween this muscle and the vertical fasciculi of the tongue. 
 
 The direction of this muscle varies according to the positions of the tongue. It is 
 vertical when the organ is contained in the buccal cavity, and is directed obliquely up- 
 ward and forward when the tongue is protruded. 
 
 The hyo-glossus is almost always divided into two portions corresponding to its double 
 origin, which are separated below by a cellular interval, and above by the posterior fas- 
 ciculus of the stylo-glossus. Albinus described them as two distinct muscles : the por- 
 tion arising from the body of the os hyoides, as the hasio-glossus ; and under the name of 
 the cerato-glossus, the portion arising from the great cornu. He also admitted a third 
 portion, under the name of the chondro-glossus, described as proceeding from the small 
 cornu. Haller, who considered this latter fasciculus a distinct muscle, states that he has 
 always been able to find it. 
 
 Relations. — On the outside it is in relation with the stylo-glossus, the mylo-hyoideus, 
 the digastricus, the sub-lingual gland, the hypo-glossal nerve, and lingual branch of the 
 fifth. On the inside, it corresponds to the lingual artery, which never passes between 
 the two portions of the muscle, to the genio-hyo-glossus, and to the middle constrictor of 
 the pharynx. 
 
 Action. — It depresses the corresponding edge of the tongue, and draws it towards the 
 OS hyoides. When the tongue has been protruded from the mouth, it assists in drawing 
 it backward. When the two muscles act together, the tongue is depressed and con- 
 tracted in its transverse diameter. 
 
 The Genio-hyo-glossus. 
 
 This is the largest of the extrinsic muscles of the tongue : it is thick, triangular, and, 
 as it were, radiated {a, Jig. 143). It arises from the superior genial process of the infe- 
 rior maxilla by a sort of tendinous tuft, from which the fleshy fibres immediately proceed 
 as from a centre, radiating backward in different directions. The posterior fibres are 
 attached to the os hyoides, either directly or through the medium of a membrane. They 
 constitute the superior genio-hyoideus of Ferrein. The more anterior fibres expand upon 
 the sides of the pharynx, occupy the interval between the os hyoides and the stylo-glos- 
 sus, and immediately cover the corresponding portion of the pharynx, or, rather, the 
 amygdaloid excavation. These fibres, which are very distinct (I was acquainted with 
 them before I was aware that they had been described by others), constitute the genio- 
 pharyngiens of Winslow. The fibres which are next in order, proceeding forward, all 
 belong to the tongue, and traverse the whole length of that organ. The most anterior 
 fibres, which are the shortest of all, having reached the lower surface of the tongue, 
 curve forward, and terminate near its point. All the others pass perpendicularly upward 
 and turn a little outward, so as to terminate in the papillary mucous membrane at the 
 side of the median line. 
 
 Relations. — On the inside it corresponds to its fellow, being separated from it by cel- 
 lular tissue frequently loaded with fat. The two muscles are perfectly distinct, and sep- 
 arable until they enter the substance of the tongue, beyond which point they cannot be 
 separated from each other. On the outside it is in relation with the sub-lingual gland, 
 the mylo-hyoideus, hyo-glossus, stylo-glossus, and lingualis muscle. The hypo-glossal 
 nerve perforates this muscle between its genio-pharyngeal and lingual portions. Its 
 lower margin corresponds to the genio-hyoideus, from which it is separated by a very 
 delicate layer of cellular tissue. Its upper margin is subjacent to the mucous membrane, 
 of which it occasions a prominence on each side of the fraenum. 
 
THE MUSCLES OF THE TONGUE. 339 
 
 Action. — By its hyoid fibres it raises the os hyoides and carries it forward ; by it:. 
 pharyngeal fibres it draws the pharynx forward and compresses its sides ; by its poste- 
 rior lingual fibres, as well as the hyoid, it carries the base of the tongue, and, conse- 
 quently, the whole organ, forward. This is the muscle by which we are enabled to pro- 
 trude the tongue from the mouth. By means of its anterior or reflected fibres, the tongue, 
 when protruded, is drawn back into the mouth ; lastly, by its median lingual fibres, the 
 tongue is made into a groove ; when one muscle acts alone, it is protruded to the oppo- 
 site side. 
 
 Such, including the palato-glossus, already described, are the extrinsic muscles of the 
 tongue : I shall not include among them the mylo-glossus of the older anatomists, and 
 described, also, by Heister and Winslow, because it appears to be nothing more than 
 that portion of the superior constrictor of the pharynx which is inserted into the mylo- 
 hyoid ridge ; nor yet the glosso-epiglottideus, a very large muscle existing in the lower 
 animals, which has been described by Albinus in the human subject as a dependance of 
 the genio-hyo-glossus. After the most careful examinations, I have never been able to 
 meet with it. 
 
 Vessels, Nerves, and Cellular Tissue. — The cellular tissue of the tongue receives arter- 
 ies and veins, and from it issue both veins and lymphatics. 
 
 The arteries consist of the proper lingual, which are very large in comparison to the 
 size of the organ, the palatine, and the inferior pharyngeal. 
 
 The veins form two sets, as in the limbs, and for the same reason : a superficial set, 
 independent of the arteries ; and a deep set, accompanying those vessels. 
 ^ The lymphatics enter the deep lymphatic glands of the supra-hyoid region. 
 
 The nerves are very large, and are derived from three sources, viz., from the ninth 
 pair, or hypo-glossal ; from the lingual branch of the fifth pair ; and from the glosso-pha- 
 ryngeal division of the eighth pair.* 
 
 The cellular tissue of the tongue is partly serous and partly adipose ; the serous por- 
 tion is chiefly situated in front, the other is more abundant behind. 
 
 The Tegumentary Membrane and Glands. — ^The tegumentary membrane of the tongue is 
 a continuation of the mucous membrane of the mouth. It is thin and slightly adherent 
 in almost all its non-papillary portion, and becomes very thick and strongly adherent 
 wherever the papillae exist. The edges of the tongue are occupied by numerous small 
 glands, continuous with the sub-lingual glands, and opening upon the lower wall of the 
 mouth by small excretory ducts. 
 
 Development. — The tongue is visible in the youngest embryos. Its early development 
 has reference to its functions, for it is an essential agent in suction, and is, consequently, 
 brought into use immediately after birth. The tongue is not double or bifid at first ; in 
 the earliest embryos it presents the appearance of a single tubercle. 
 
 Uses of the Tongue. — The tongue has two very distinct uses. It is the organ of taste, 
 and it is also a movable organ. In this place we shall consider it in the latter capacity 
 only. The movements of the tongue are concerned in the prehension of food, in suction, 
 in mastication, in tasting, in deglutition, in articulation, and in playing upon wind- 
 instnmients. 
 
 In order to fulfil such a variety of uses, it is organized so as to be capable of moving 
 in every direction. Its movements are either extrinsic or intrinsic. The extrinsic move- 
 ments, or those of the whole tongue, may be ascertained from our knowledge of the sin- 
 gle or combined actions of its extrinsic muscles. Thus, it may be protruded from the 
 mouth, drawn back into that cavity, inclined to the right or to the left side, directed up- 
 ward or downward, or carried into any intermediate position. In its intrinsic move- 
 ments it may be contracted transversely by the transverse fibres, diminished in length 
 by its longitudinal fibres, and contracted vertically and rendered concave by its vertical 
 fibres ; lastly, its apex can be carried upward by the superior, and downward by the 
 inferior longitudinal fibres. 
 
 By far the most varied, precise, and rapid motions of this organ are required in the ar- 
 ticulation of sounds, in which it is one of the chief agents. In consequence of this use, 
 which is by no means the result of a special conformation (for, by constant practice, an- 
 imals, whose tongues are very different from ours, may be taught to articulate), the 
 tongue is associated with, and becomes one of the principjd instruments of the mind. It 
 is the organ by which thought is most conamonly expressed. This use is peculiar to 
 man. 
 
 * The ninth nerve is distributed to the muscles, the lingual nerve to the mucous membrane of the anterior 
 part and sides, and the glosso-pharyngeal to that of the base of the tongue. (See Organ of Taste.) 
 
 I have lately seen a considerable branch of the facial nerve terminating in the tongue ; it was given oft 
 from the facial nerve at its exit from the stylo-mastoid foramen, crossed obliquely in front of the styloid pro- 
 cess with which it was in contact, passed in front of the stylo-pharyngeus muscle externally to the tonsil and 
 parallel to the glosso-pharyngeal nerve, which was situated behind it, communicated with that nerve by sev- 
 eral arches, and divided into two branches at the base of the tongue, one of which ran along the edge or that 
 organ, and the other anastomosed by a loop with the glosso-pharyngeal : from this loop some filaments passed 
 off, to be distributed in the usual manner. 
 
 The opposite side did not exhibit a corresponding arrangement. 
 
SPLANCHNOLOGY. 
 
 . . - .ziki... - The Salivary Glands. 
 
 Besides the labial, buccal, and palatine glands found in the cavity of the mouth, which, 
 by most anatomists, have been confounded with the follicles or muciparous crypts, there 
 exists around this cavity a particular glandular apparatus, forming a sort of chain or col- 
 lar, symmetrically extended along the rami and body of the lower jaw. This chain is 
 interrupted so as to form six glandular masses, three on each side, named, from their sit- 
 uation, the parotid, sub-maxillary, and sub-lingual glands.* 
 
 The Parotid Gland. 
 
 The parotid gland {p, fig. 144), so called from being situated below and in front of 
 Fig. 144. the external auditory meatus {napa, near, ovc, wrof, the 
 
 ear), fills the parotid excavation. It is bounded in front 
 by the posterior edge of the ramus of the lower jaw ; 
 behind, by the external auditory meatus and the mas- 
 toid process ; above, by the zygomatic arch ; below, by 
 the angle of the lower jaw ; and on the inside, by the 
 styloid process and the muscles which proceed from 
 it. This gland has given its name to the region occu- 
 pied by it. 
 
 It is the largest of all the salivary glands, and even 
 exceeds all the rest put together. Its form is irregular, 
 and is determined by that of the surrounding parts, upon 
 which it is moulded like a piece of soft wax. Its su- 
 perficial portion is broad, but it suddenly becomes con- 
 tracted when it dips behind the ramus of the jaw. 
 
 In order to obtain a good idea of the size and shape 
 of this gland, it must be removed entire from the irreg- 
 ular mould in which it is lodged. It has been compared 
 to a pjTamid, of which the base is directed outward, and the apex inward. 
 
 Relations. — Its external surface, or base, is broad, oblong from above downward, irreg 
 tilarly quadrilateral, and lobulated at the edges ; it is sub-cutaneous, being separated from 
 the skin, however, by the parotid fascia and the risorius of Santorini, when that muscle 
 exists. + 
 
 Its anterior surface is grooved so as to embrace the posterior edge of the ramus of the low- 
 er jaw. A bursa, or some loose cellular tissue, facilitates the movements of these parts. 
 This surface is also in relation with the internal pterygoid muscle, the stylo-maxillary 
 ligament, and the masseter muscle, on the external surface of which it is prolonged to a 
 greater or less extent (see fig. 144) in different individuals, and is separated from it an- 
 teriorly by the ramifications of the facial nerve, by some loose cellular tissue, and by the 
 transverse artery of the face. 
 
 Its posterior surface is in relation %vith the cartilaginous portion of the external audito 
 ry canal, being moulded upon its convexity, and adhering to it by very dense cellular 
 tissue : it corresponds also to the mastoid process, the stemo-cleido-mastoid and digas- 
 tric muscles, and indirectly to the transverse process of the atlas. This surface is ex 
 tremely irregular, adheres by means of dense cellular tissue, and is dissected off with 
 great diflieulty in an attempt to remove the entire gland. 
 
 On the inside it is reduced to a mere border, which corresponds to the styloid process, 
 and the muscles and ligament connected with it. It sends off a considerable prolonga- 
 tion into the space which separates the styloid process and its muscles from the inter- 
 nal pterygoid : but the most important relation of this border is with the external carot- 
 id artery, for which it furnishes a groove, and sometimes, even, a complete canal. 
 
 Its upper extremity corresponds to the zygomatic arch and the temporo-maxillary ar- 
 ticulation. 
 
 Its lower extremity fills up the interval between the angle of the jaw and the sterno- 
 mastoid, and is separated from the sub-maxillary gland (m) by a very thick fibrous septum. 
 Besides the relations already indicated, the parotid has others with the vessels and 
 nerves which traverse it at different depths : these may be called its intrinsic or deep re- 
 lations. Thus, the external carotid artery almost always perforates the gland near its in- 
 ner side ; the temporal artery {see fig. 144), the transversalis faciei, and the anterior au- 
 ricular, which commence in the substance of the gland, also traverse it in various direc- 
 tions. We also find within it the temporal vein, which is a communicating branch be- 
 tween the external and internal jugulars ; the trunk of the facial nerve is at first placed 
 behind the gland, then penetrates it, and divides into two or three branches, which again 
 subdivide and traverse it in all directions. The auricular nerve, a branch of the cervi 
 
 * The continuity of this glandular chain, admitted by some anatomists, is only apparent. A fibrous septum 
 always intervenes between the sub-maxillary and the parotid glands. 
 
 t In a female in whom I dissected the parotid gland, the risorius arose from the superior semicircular 
 line of the occipital bone by two distinct fasciculi, which, passing downward and forward, united opposite the 
 apex of the mastoid process, and then proceeding horizontally, expanded upon the parotid gland. Some of the 
 fibres reached the commissure of the lips, but the greater number were lost upon the parotid fascia. 
 
THE PAROTID GLAND. 341 
 
 cal plexus, also passes through it very superficially.* The parotid gland, by a remark- 
 able exception, always contains in its substance, a little below the surface, several lym- 
 phatic glands, which may be readily distinguished by their red colour from the proper 
 tissue of the gland. It may be imagined that a morbid development of these glands may 
 have often been mistaken for disease of the parotid itself 
 
 Structure. — A thick fibrous membrane covers the parotid glands, and sends prolonga- 
 tions into it which divide it into lobes, and these, again, into glandular lobules. The ac- 
 tual structure of the gland, therefore, depends upon the nature of these lobules ; and, 
 without entering into details which belong more properly to general anatomy, it may be 
 stated that it has been shown, by the aid of the simple microscope, that each lobule is a 
 porous, spongy body, something like the pith of the rush, and provided with afferent ves- 
 sels, viz., the arteries ; and efferent vessels, i. e., the veins and excretory ducts.^ The re- 
 lations of the nerves and lymphatic vessels with these granules have not been accurate- 
 ly determined. 
 
 The parotid arteries are very numerous ; some of them arise directly from the exter- 
 nal carotid ; others from its branches, more particularly from the superficial temporal, 
 the transversalis faciei, and the anterior and posterior auricular. 
 
 The veins have similar names, and follow the same direction as the arteries. There 
 is a parotid venous plexus. 
 
 The lymphatic vessels are little known : they terminate partly in the glands at the an- 
 gle of the jaw, and partly in those which lie in front of the auditory meatus. I have 
 already said that one or more lymphatic glands are always situated in the parotid gland, 
 a few hues below its surface. 
 
 The nerves are derived from the anterior auricular (a branch of the cervical plexus) 
 and from the facial nerve : they seem to be lost in the substance of the gland. 
 
 The Parotid Duct. — A small excretory duct (resulting from the union of its terminating 
 vesicles) proceeds from each lobule, and unites almost immediately, at a very acute an- 
 gle, with the ducts of the adjacent lobules. From the successive union of all these ducts 
 a single canal results, which emerges from about the middle of the anterior margin of 
 the gland : this is the parotid duct (s, fig. 144), called also the du^t of Steno, although it had 
 been previously described by Casserius. It passes horizontally forward, about five or 
 six lines beneath the zygomatic arch, across the masseter, and at right angles to its 
 fibres. At the anterior border of the masseter it changes its direction, curves in front 
 of a mass of fat situated there, dips perpendicularly into the fat of the cheek, perforates 
 the buccinator in the same direction, and glides obhquely, for the space of several lines, 
 between that muscle and the mucous membrane of the mouth, which it pierces opposite 
 the intervEd between the first and the second upper great molar teeth, almost on a level 
 with the middle of their crown. 
 
 The mode in which the Stenonian duct opens into the buccal cavity does not appear 
 to me to have been sufficiently well understood. It exactly resembles the manner in 
 which the ureters enter the bladder. Thus, it glides obliquely for a certain distance be- 
 neath the mucous membrane, a fact that may be easily determined by perforating the 
 cheek at the point where the duct passes through the buccinator, and then measuring 
 the interval between this perforation and the buccal orifice of the canal : this interval 
 varies from two to three lines in extent. Again, the buccal orifice is oblique, like the 
 vesical opening of the ureter, so that it is extremely easy to pass a fine probe into it. 
 
 The duct of Steno is often accompanied by an accessory glandt (glandula socia paroti- 
 dis, see fig. 144), situated between it and the zygomatic arch. The duct of this little 
 gland opens into the main canal. I have seen two small accessory glands situated above 
 the canal, one at the middle and the other at the anterior part of the masseter. Lastly, 
 as the parotid duct is passing through the buccinator, it is surrounded by a series of 
 glands continuous with those of the cheeks, called molar glands, the ducts of some of 
 which appear to open into the canal, and those of others directly into the mouth. Al- 
 though it is not flexuous, the canal, when separated from the surrounding parts, will be 
 found much longer than it appears at first sight. 
 
 Fig. 145. 
 
 * These relations prove the almost absolute impossibility of extirpating this gland 
 by a cutting instrument, and of compression after Desault's method, for the cure 
 of salivary fistulae. Compression, which is extremely painful, on acxjount of the 
 number of nerves passing through it, can only affect its superficial portion. 
 
 t [Weber has succeeded in distending with mercury the ducts {d,fig. 145) of the 
 parotid gland in the infant, and has shown that they terminate in closed vesicular 
 extremities (c) about - A ^j of an inch in diameter, three times that of the capillary 
 vessels ramifying upon them. See Mullet's Physiology, translated by Baly, p. 447 ; 
 and MuIUt on the Glands, translated by Solly, p. 69.— (Tr.) 
 
 In the early embryo of the sheep, this gland consists of a canal which opens into 
 the mouth by one extremity, but is closed at the other, and has numerous short 
 hollow branches projecting from it into a granular blastema : as development ad- 
 vances, the blastema is absorbed, and the ramified canal, increasing in length, be- 
 comes iitill more ramified, so as to form the ducts with their closed vesicular termi- 
 nations.] * Magnified fifty timcf. 
 
 t Desault found this gland very large in a subject where the corresponding parotid was atropmed. 
 
m 
 
 SPLANCHNOLOGY. 
 
 Relations. — The Stenonian duct is sub-cutaneous and superficial where it passes orer 
 the masseter ; it is protected by a large quantity of fat, and, in front of the maisseter, by 
 the zygomaticus major. A considerable branch of the facial nerve, and some arteries 
 derived from the transversalis faciei, run along this canal. 
 
 Structure. — An exaggerated idea is generally entertained of the thickness of the duct 
 of Steno ; it is only thick at its anterior part, where it is strengthene(^ by an expansion 
 of the aponeurosis of the buccinator muscle. When freed from the surrounding fat, it 
 is not thicker than most other ducts, the ureters, for example. The notion that it is in- 
 extensible is also incorrect. It is true, however, that the diameter of its canal is not 
 in proportion to the size of the gland. It is formed by two membranes : one external, 
 the nature of which is not well known ; the other internal, consisting of a prolongation 
 of the mucous membrane of the mouth. Its arteries and veins are very large. 
 
 The Sub-maxillary Gland. 
 
 The sub-maxillary gland {m,fig. 144) is situated in the supra-hyoid region, and part- 
 ly behind the body of the lower jaw ; it is bounded by the reflected tendon of the digas- 
 tricus, below which it ahnost always projects. 
 
 Size and Figure. — It is much smaller than the parotid, but larger than the sub-lingual. 
 It is oblong from before backward, elliptical, irregular, and divided into two or three 
 lobes by some deep fissures. 
 
 Relati(ms. — On the outside and below, it corresponds to a depression on the inferior 
 maxillary bone, in which it is completely lodged when the jaw is depressed. When, 
 on the other hand, the head is bent backward upon the neck, the gland appears almost 
 entirely in the supra-hyoid region, and is in relation with the platysma, being separated 
 from it by the cervical fascia, to which it is united by cellular tissue of so loose a tex- 
 ture, that it may be called a synovial bursa. This surface of the gland is also in rela- 
 tion with the internal pterygoid muscle and the numerous lymphatic glands situated 
 £dong the base of the jaw. On the inside and above, it corresponds to the digastric, my- 
 lo-hyoid, and hyo-glossus muscles, and to the hypo-glossal and lingual nerves. 
 
 The sub-maxillary gland almost always forms a prolongation of variable size and shape 
 above the mylo-hyoideus. Sometimes the lobules of which it is composed are situated 
 in lines, so as to appear like the Whartonian duct, or, rather, a second canal running 
 parallel to it. Most commonly, this prolongation is of considerable size and irregular, 
 and forms, as it were, a second sub-maxillary gland. 
 
 The most important relation of the gland is to the facial artery (a), which runs in a 
 groove on its posterior border, and upon the contiguous part of its external surface. 
 Sometimes this groove is prolonged forward, and divides the gland into two unequal 
 parts. We cannot avoid seeing the great analogy between this arrangement and that 
 of the external carotid artery, with regard to the parotid gland. 
 
 Structure. — This is identical with that of the parotid. Its investing fibrous membrane 
 is weaker, and stiU more diflicult of demonstration. The arteries are numerous, and 
 arise from the facial and the lingual. The veins correspond to them. The b/mpkatic 
 vessels are little knovra, and enter the neighbouring glands. The nerves are derived 
 from the lingual and the myloid branch of the dental. I should remark, that all the nerves 
 proceeding from the sub-maxillary ganglion are destined for this gland. 
 
 The excretory duct of the sub-maxillary gland is called the Whartonian duct, although 
 it was really discovered by Van Home. It is formed by the successive union of all the 
 small ducts proceeding from the lobules ; it leaves the gland at the upper bifurcation of 
 its anterior extremity, and, consequently, above the mylo-hyoideus, and is directed ob- 
 liquely upward and inward, parallel to the great hypo-glossaJ and lingual nerves. It is 
 at first placed between the mylo-hyoid and hyo-glossus muscles, and then ghdes between 
 the genio-hyo-glossus and the sub-hngud gland, to the inner surface of which it is at- 
 tached.* I have never succeeded in determining whether it receives any excretory 
 duct or ducts from this gland. Having reached the side of the fraenum linguae, the duct, 
 which is sub-mucous in the whole of the portion corresponding to the sub-lingual gland, 
 changes its direction, passes forward, and opens by an extremely narrow orifice upon 
 the simimit of a prominent and movable papilla found behind the incisor teeth. This 
 orifice, which can scarcely be seen by the naked eye, was found to admit a hog's bristle 
 in a particular case presented to the Anatomical Society by M. Robert.t Bordeu has 
 correctly described the appearance of this orifice by the term ostiolum umbilicale. 
 
 The duct of Wharton is remarkable for the thinness of its coats, which are not thick- 
 er than those of a vein ; for its great calibre, which exceeds that of Steno's duct ; for 
 the extensibility of its coats, the canal sometimes acquiring an enormous size ; and, last- 
 ly, for its proximity to the mucous membrane of the mouth, which causes it, when much 
 dilated, to project into the buccal cavity. 
 
 * [See_^^. 146, in which the gland itself (m) hangs down, jesting upon the hyo-glossus ; the digastric and 
 mylo-hyoid muscles and half the lower jaw have been removed.] 
 
 t This was observed in a shoemaker ; the bristle had become the nucleus of a salivary calculus. 
 
THE SUB-LINGUAL GLAND. 343 
 
 ..-.^^.., .; ^^^^i . The Sub-lingual Gland. 
 
 The sub-lingual gland {I, fig. 146), which may be regarded as an agglomeration of small- 
 . cr glands analogous to those of the lips and palate, is sit- 
 . uated in the sub-lingual fossa of the lower jaw, at the side J^g. 146^ 
 
 , of the symphysis menti : it is much smaller than the pre- 
 ceding gland, with which it is sometimes continuous. Its 
 shape 8 oblong, like that of an olive flattened at the sides. 
 The following are its relations : It is subjacent to the 
 mucous membrane, beneath which its upper edge forms 
 j^a prominent ridge, running from before backward along 
 ,the sides of the fraenum ; its lower edge rests upon the 
 mylo-hyoid muscle ; its external surface corresponds 
 partly to the mucous membrane and partly to the sub-lin- 
 gued fossa ; its internal surface is in relation with the 
 mucous membrane, with the genio-hyo-glossus (from 
 which it is separated by the lingual nerve), with the Whar- 
 tonian duct (which, we have seen, closely adheres to it), 
 and with the ranine vein. Its anterior extremity touches 
 the gland of the opposite side. Its posterior extremity and its lower edge are embraced 
 by the lingual nerve, which gives numerous filaments to it. A small glandular prolonga- 
 tion also proceeds from its posterior extremity, and runs along the edge of the tongue. 
 
 Structure. — Precisely similar to that of the other salivary glands. Its arteries arise 
 .from the sub-mental and sub-lingual. Its veins bear the same name. Its nerves are 
 niunerous, and are derived from the lingual. 
 
 Its excretory ducts, called also the ducts of Rivinus, from their discoverer, are seven 
 or eight in number. They open along the sub-lingual crest : their orifices may be shown 
 by placing a coloured fluid in the mouth. Most anatomists state, that several of the 
 ducts of this gland open into the Whartonian duct. 
 
 General Characters of the Salivary Glands. — The salivary glands present the following 
 general characters : 
 
 1. They are situated around the lower jaw, extending along its body and rami, from 
 the condyles to the symphysis ; they are in relation, on the one hand, with the maxilla- 
 ry bone, and on the other with numerous muscles, so that they are subjected to consid- 
 erable compression during the movements of the lower jaw. 2. They all have direct 
 relations with large arteries, which communicate their pulsations to them. 3. They re- 
 ceive vessels from a great number of points, and the vessels themselves are very numer- 
 ous. 4. They are penetrated by many of the cerebro-spinal nerves, of which some only 
 pass through, but a certain number terminate in them. 5. In structure they resemble 
 the pancreas and the lachrymal glands ; they have no special fibrous investment to isolate 
 them completely from the surrounding parts ; they have no precise form, and they are 
 subdivided into lobes and lobules. 6. Their excretory ducts pour their secretion into the 
 mouth, i. e., the parotids between the cheeks and the teeth, the sub-maxillary and the 
 sub-lingual glands behind the lower incisors, on each side of the apex of the tongue. 
 This distribution of the means of insalivation between the two cavities into which the 
 mouth is divided deserves the attention of physiologists. 
 
 The Buccal Muccnis Membrane. 
 
 The buccal mucous membrane is continuous with the skin at the free edges of the lips ; 
 it lines their posterior surface, and is reflected from them upon each of the maxillary 
 bones, forming a cul-de-sac or trench, and in the median line a small fold, called the frae- 
 niun of the Ups. About a -line and a half or two lines from the free border of the lips, 
 it changes its character, and constitutes the gums, which are reflected upon themselves, 
 so as to become continuous with the fibro-mucous membrane, called the alveolo-dental 
 periosteum. 
 
 In the lower jaw the mucous membrane passes from the alveolar border to the lower 
 wall of the mouth, and from it to the under surface of the tongue. At the point of re- 
 flection in the median line, it forms the fraenum hnguae. From the under surface of the 
 tongue, the raucous membrane passes over its edges and upper surface, where it pre- 
 sents the peculiarities already described ; and in being reflected from the base of the 
 tongue to the epiglottis, it forms three folds, the glosso-epiglottid, so as to become con- 
 tinuous on the one hand with the mucous membrane of the larynx, and on the other with 
 that of the pharynx. 
 
 In the upper jaw it is extended from the upper alveolar border upon the roof of the pal- 
 ate, passing over the anterior and posterior palatine canals, which it closes, but does not 
 enter. From the roof of the palate it passes upon the velum, and is continuous with the 
 nasal mucous membrane at its free edge. On the sides it forms two large folds for the 
 pillars of the fauces, lines the amygdaloid excavation, covers the tonsil, and becomes 
 continuous with the mucous membrane of the base of the tongue and of the pharynx. 
 
#44 SPLANCHNOLOGY. 
 
 At the sides of the buccal cavity the mucous membrane is reflected from both the alveo- 
 lar borders upon the inner surface of the cheeks, and thus forms two trenches. At the 
 anterior edge of the ramus of the jaw, behind the molar teeth, it is elevated by a saliva- 
 ry gland, which marks the limit between the cheeks and the pillars of the fauces. Inside 
 this prominence it forms a cul-de-sac. 
 
 The buccal mucous membrane sends off prolongations into the numerous canals which 
 open into the mouth. Thus, on the floor of the mouth there are two for the Whartonian 
 ducts, and several for the small ducts of the sub-lingual glands. Two others are seen on 
 the inner sides of the cheeks for the ducts of Steno ; and it is also clear that it must pen- 
 etrate into the thousands of other orifices with which the mouth is studded (those of the 
 buccal, labial, palatine, and other glands). But in all these prolongations its structure 
 is modified, and it becomes exceedingly thin. It has been proved that it lines not only 
 the larger ducts, but even their minutest subdivisions. Thus, there is a kind of parotitis, 
 which consists in inflanunation of the lining membrane of the excretory ducts of that 
 gland ; and then all the canals are filled with muco-puriform secretion, which escapes 
 by the buccal orifice when the gland is compressed. The numerous openings on the 
 surface of the tonsil are formed by the prolongations of this membrane into the cavities 
 situated in its interior. 
 
 Although the different parts of the buccal mucous membrane are continuous, they do 
 not all possess the same characters. Compare, for instance, in regard to their density, 
 thickness, and closeness of adhesion to the subjacent tissues, the mucous membrane of 
 the gums and palate with that of the lips and cheeks, or the membrane covering the low- 
 er with that upon the upper surface of the tongue, or the mucous membrane of the free 
 edge of the velum palati with that of the arches and the amygdaloid excavation. 
 
 The two principal characters of the buccal mucous membrane are the following : 1 . 
 The presence of an epidermis or epithelium* (as it is called in mucous membranes). 
 This can be distinctly demonstrated by maceration, or by the action of boiling water or 
 some acid ; by any of these means a pellicle is raised, having all the characters of an ep- 
 idermis. It is very thick upon the gums, the roof of the palate, and upon the tongue, 
 where it forms a horny sheath to each papilla. To the existence of this membrane, and 
 of the fluid with which it is constantly kept moist, we must attribute the possibility of 
 applying, or, rather, running, a red-hot iron over the surface of the tongue without burn- 
 ing the part. 2. The multiplicity of small subjacent glands, so near to each other in some 
 parts as to form a continuous layer. These glands should be carefully distinguished 
 from the muciparous follicles or crypts, with which many modern anatomists have 
 conunonly confounded them. To these two characteristics a third may be added, pe- 
 culiar to some portions of the buccal mucous membrane, viz., that it is supported by a 
 very dense fibrous tissue, with which it is completely united. This fibrous layer is per- 
 fectly distinct from the periosteum, and from its presence the mucous membrane should 
 be arranged among the fibro-mucous membranes. 
 
 The Pharynx. 
 
 The pharynx (^opvyf, the throat,t 1, 2, ^,fig. 140), long confounded with the cesopha- 
 gus, under the common name of gula or oesophagus, is a muscular and membranous semi- 
 canal, perfectly symmetrical, and situated in the median line : it is a sort of vestibule, 
 common to the digestive and the respiratory passages, intermediate between tlie buccal 
 and nasal cavities on the one hand, and between the cesophagus and larynx on the other. 
 It is situated deeply in front of the vertebtral column, extending from the basilar process 
 of the occipital bone to opposite the fourth or fifth cervical vertebra and the cricoid 
 cartilage. It therefore corresponds to the parotid, and partly to the supra-hyoid regions. 
 
 Its dimensions deserve particular attention. It is smaller than the mouth, but larger 
 than the oesophagus, which, compared to it, resembles the tube of a funnel. Hence it 
 follows, that foreign bodies, which have been able to pass along the mouth and pharynx, 
 may be arrested in the oesophagus. 
 
 In length it is from 4 to 4^ inches, which may be increased to 5^, or even 6^, by dis- 
 tension, and reduced to 2^ by the greatest possible contraction, which is limited only by 
 the contact of the base of the tongue with the velum palati rendered horizontal. The 
 length of the pharynx, therefore, may be made to vary about 4 inches. 
 
 The pharynx undergoes these extreme variations both in deglutition and in modula- 
 ting the voice ; in effecting which latter purpose, it acts in the same way as the tube of 
 a clarinet or flute. Thus considered, the entire length of the pharynx may be divided 
 into three parts, a nasal (1,/^. 140), a buccal or guttural (2), and a laryngeal (3) portion. 
 It may be easily seen that the variations in length affect almost exclusively the buccal 
 portion, into which the air is received after escaping from the larynx. Now these vari- 
 ations in the length of the pharynx have the same influence over the compass of the hu- 
 
 * [The existence of an epithelium is common to all mucous membranes ; that of the buccal cavity is of the 
 squamous variety.] 
 
 t The term pharynx had no well-defined meaning among the ancients : they sometimps used it to designate 
 •he phftrynz, properly so called ; sometimes the larynx. 
 
THE PHARYNX. 345 
 
 man voice as the differences in the lengths of the tubes of wind-instruments h.iif ii.ori 
 the sounds produced by them. 
 
 The breadth of the upper or nasal portion of the pharynx is measured by the interval 
 between the posterior margins of the internal pterygoid plates : it is about one inch, and 
 is invariable. In the buccal portion the same diameter is measured by the interval be- 
 tween the posterior extremities of the alveolar borders, and is about two inches : it may 
 be diminished to one inch by the contraction of the constrictor muscles. The breadth 
 of the larj-ngeal portion is measured, first, by the interval between the summits of the 
 great cornua of the os hyoides, where it is about one inch and near two lines ; then by 
 the interval between the superior cornua of the thyroid cartilage, which is an inch and 
 two or three lines ; and, lastly, by the interval between the inferior cornua of the same 
 cartilage, about eleven or twelve lines. The contraction of this laryngeal portion may 
 be carried to complete obliteration of the cavity. 
 
 Both the buccal and laryngeal portions, therefore, are capable of contraction, and this 
 always takes place in deglutition, in order to force down and compress the alimentary 
 m£iss. Contraction of the buccal portion also takes place in the modulation of sounds : 
 it exerts the same influence over the compass of the human voice as the contraction of 
 the tubes of the flute or clarinet does over the notes of those instruments. 
 
 The antero-'posterior dimensions of the pharynx are not subject to the same variations as 
 the transverse and vertical, on account of the presence of the vertebral column. Its en- 
 largement in this direction is produced during that period in the act of deglutition when 
 the leuynx and os hyoides are carried forward and upward, and its diminution at the time 
 when the same parts are carried upward and backward. The antero-posterior diameter 
 of the pharynx depends upon the length of the basilar process of the occipital bone. 
 
 Figure. — The pharynx does not form a complete cavity with distinct and separate 
 walls, but, rather, hsdf or two thirds of a canal, which is completed in part by several or- 
 gans otherwise not belonging to it. Moreover, the pharynx, from its commencement 
 down to the larynx, is habitually open, and in a state of tension ; its walls are never in 
 apposition : an important circumstance in reference to the continual passage of air 
 through its nasal and buccal portions. This tension depends on its attachment to the 
 basilar process, and to the fixed points at its sides, and also upon the tendinous struc- 
 ture of its upper portion. Opposite the larynx the tension ceases to exist. 
 
 The pharynx, as well as all other hollow organs, presents an external and an internal 
 surface. 
 
 The External Surface. — ^This is in relation behind, by a plane surface, with the verte- 
 bral column (see fig. 140), from which it is separated by the long muscles of the neck 
 and the anterior recti of the head. It glides, by means of some very loose cellular tissue, 
 upon the fascia covering the muscles of that region ; and when, from the effect of in- 
 flammation, this cellular tissue becomes dense, the movements of deglutition cannot be 
 performed, and dysphagia is the result. The relation of the pharynx to the vertebral col- 
 lunn accounts for congestive abscesses of the neck sometimes opening into the pharynx. 
 
 At the sides the pharynx is separated from the internal pterygoid muscle by a triangular 
 space, broad below and narrow above, occupied by the internal carotid artery, the inter- 
 nal jugular vein, and the pneumogastric, glosso-pharyngeal, hypo-glossal, and spinal ac- 
 cessory nerves, all being surrounded by very loose cellular tissue. The sides of the 
 pharynx are also indirectly in relation with the parotid gland and the styloid muscles. 
 Lower down, the pharynx corresponds to a great number of lymphatic glands, and to the 
 external carotid artery and its branches. 
 
 The Internal Surface. — In order to examine this surface, it is necessary to open the 
 pharynx from behind by a vertical incision. We shall then perceive that this structure 
 only exists behind and at the sides, but that in front it presents a great number of open- 
 ings {see figs. 140, 141), the arrangement of which is of great interest. 
 
 Proceeding from above downward, we find, 1. The two posterior openings of the na- 
 sal fossa (I), quadrilateral in form, having their longest diameter vertical, and separated 
 from each other by the posterior edge of the septum. On looking into them, we see the 
 posterior extremities of the turbinated bones and the terminations of the several mea- 
 tuses. 2. The upper surface of the velum palati (c a), forming an inclined plane, which 
 directs the mucous secretions into the throat. 3. The isthmus of the fauces (2), of a sem- 
 icircular form, divided into two arches, and exhibiting the pillars, the amygdaloid ex- 
 cavation, and the prominence of the tonsils. 4. The superior opening of the larynx (3), 
 the plane of which is directed obliquely upward and forward {see fig. 140) ; the epiglottis 
 {i,fig. 140), which is ordinarily erect, closes this opening by becoming depressed like a 
 valve. 5. The posterior surface of the larynx, with its two lateral and triangular grooves, 
 broad above and narrow below, which have been regarded as specially intended for the 
 swallowing of liquids, which thus pass on each side of the laryngeal opening. 
 
 It is extremely curious and highly important to study all the objects displayed in the 
 complicated mechanism of the pharynx : by so doing, we learn how the air passes from 
 the nasal fossa and mouth into the pharynx, and thence into the larynx, into which it is 
 drawn by the active expansion of the thorax, without ever entering the (esophagus ; 
 
 Xx 
 
 1 
 
a^ SPLANCHNOLOGY. 
 
 how the mucous secretions of the nose, or blood, can pass from the nose down into the 
 mouth and throat ; how instruments may be introduced from the nasal fossae and buccal 
 cavity into the oesophagus and larynx, or drawn from the nose into the mouth ; and, 
 lastly, how solids and liquids can pass into the oesophagus without entering the air-pas- 
 sages, or why they sometimes take this irregular course. 
 
 The posterior wall of the ■pharynx is broader in the buccal region than either above or 
 below : it may be partially seen through the isthmus of the fauces in the living subject. 
 There is no folding of the membrane upon any part of this wall : we only find a few 
 glands forming projections beneath the lining membrane. 
 
 On each lateral wall is seen the expanded orifice of the corresponding Eustachian tube 
 {A, fig. 140), and a groove leading from it downward and inward. This orifice corre- 
 sponds precisely to the posterior extremity of the lower turbinated bone : an important 
 relation, because it serves as a guide in the now common operation of introducing a 
 catheter into the Eustachian tube. 
 
 The roof of the pharynx corresponds to the basilar process : it may be reached by the 
 finger introduced into the mouth, if it be curved directly upward. 
 
 There is no very distinct line of demarcation, either internally or externally, between 
 the pharynx and the oesophagus (y, fig. 140). Their limits are established by a sudden 
 narrowing of the tube,* by a change of colour in the lining membrane, and by a change 
 in the direction and colour of the muscular fibres, which are red in the pharynx and 
 much paler in the oesophagus. 
 
 Structure of the Pharynx. — The pharynx is composed of an aponeurotic portion, of 
 muscles, of vessels and nerves, and of a lining mucous membrane. 
 
 The aponeurotic portion, or framework of the pharynx, is composed of the cephalo-pha- 
 ryngeal aponeurosis and of the petro-pharyngeal aponeurosis. 
 
 The cephalo-pharyngeal, or posterior aponeurosis of the pharynx, arises from the lower 
 surface of the basilar process, from the Eustachian tubes, and from the contiguous parts 
 of the petrous portions of each temporal bone : it is continuous above with the thick pe- 
 riosteum which covers the basilar process, is prolonged vertically downward, and, grad- 
 ually diminishing in thickness, is lost after extending about an inch and a half or two 
 inches. On this membrane the constrictor muscles of the pharynx terminate. 
 
 The petro-pharyngeal, or lateral aponeurosis of the pharynx, arises from the petrous 
 portion of the' temporal bone, internally to the inferior orifice of the carotid canal, by a 
 very thick tendinous bundle, continuous, at a right angle, with the cephedo-pharyngeal 
 aponeurosis ;i it then descends along the sides of the pharynx, and splits into bundles, 
 which are inserted into the pterygoid fossa between the internal pterygoid muscle and 
 the circumflexus palati, separating these muscles from each other. From thence it 
 gives off to the posterior extremity of the inferior alveolar border a fibrous prolongation, 
 to the front of which the buccinator muscle is attached. This aponeurosis covers the 
 tonsil, to which it is closely united. It is prolonged downward as far as the upper bor- 
 der of the OS hyoides, in order to form the framework of the side and lower part of the 
 pharynx. 
 
 Muscles of the Pharynx. 
 The muscles of the pharynx are divided into intrinsic and extrinsic. 
 
 The Intrinsic Muscles. 
 The intrinsic muscles have a membranous form, and are arranged in three successive 
 imbricated layers. Santorini described a great many muscles in the pharj'nx, on ac- 
 count of their numerous attachments ; but Albinus has reduced them to three on each 
 side, named constrictors, distinguished into an inferior, a middle, and a superior. Chaus- 
 sier united all the muscles which enter into the composition of the pharynx under the 
 collective name of les stylo-pharyngiena. The division of Albinus has been generally and 
 justly preferred. 
 
 ^' !*'• The Inferior Constrictor. 
 
 This is a membranous muscle (w,figs. 141, 147), of a lozenge, 
 or, rather, a trapezoid shape, the most superficial and the thick- 
 est of all the muscles of the pharynx, and is situated at the low- 
 er part of that cavity. It is attached, on the one hand, to the cri- 
 coid and the thyroid cartilages, and, on the other, to the fibro- 
 cellular raphe, along the posterior median line of the pharynx 
 (crico-pharyngien and thyro-pharyngien, Valsalva, Winslow, and 
 Santorini). It might be called the crico-thyro-pharyngeus. It 
 -m arises upon the side of the cricoid cartilage, from a triangu- 
 lar space bounded in front by the crico-thyroideus (a, fig. 147), 
 
 * [This occurs exactly opposite the cricoid cartilage.] 
 
 + The superior cervical ganglion of the sympathetic nerve lies upon the angle 
 formed by these two aponeuroses, 
 
MUSCLES OP THE PHARYNX. 347 
 
 from which it often receives some fibres, and behind by the crico-arytenoideus posticus 
 (i,fig. 141). 
 
 Its thyroid origins are much more extensive, and take place from an imaginary ob- 
 lique line on the outer surface of that cartilage, from the two tubercles at the extremi- 
 ties of that line, and from the entire surface behind it ; also from the upper and poste- 
 rior borders, and from the corresponding inferior comu of the same cartilage. Having 
 thus arisen by two very distinct digitations, the fleshy fibres pass in different direc- 
 tions : the inferior fibres, short and horizontal, proceed directly inward ; the superior be- 
 come longer, and are directed more obliquely upward, in proportion as they approach 
 the upper part of the muscle : they terminate by an expanded border of much greater 
 extent than the outer border, and the upper extremity of which rarely extends above 
 the middle of the pharynx. The transverse direction and the shortness of the inferior 
 fibres have obtained for them the name of the (Esophageal muscle ( Wiiislow, Santorini). 
 
 Relations. — Covered by a dense cellular membrane, which surrounds the entire pha- 
 rynx, and which might be regarded as the proper sheath of its muscles, the inferior con- 
 strictor has the same relations posteriorly as the pharynx itself Externally it is cov- 
 ered by the sterno-thyroid muscle and the thyroid body. It covers the middle constric- 
 tor, the stylo-pharjmgeus, and palato-pharyngeus, and, for a great part of its extent, it is 
 in contact with the mucous membrane of the pharynx (see figs. 141, 147). The recur- 
 rent larjTigeal nerve passes undSr the lower margin of this muscle, near its cricoid at- 
 tachment, in order to enter the larynx. Its ufper margin is well defined from the other 
 constrictors by a tolerably distinct ridge, and by the passage of the superior laryngeal 
 nerve beneath it. Winslow states that he has seen some fibres of the muscle arise from 
 the thyroid body ; and Morgagni, that he has traced some from the first ring of the 
 trachea. 
 
 Action. — It is simply a constrictor in its lower portion : its upper fibres act as a con- 
 strictor, a depressor, and a tensor of the posterior wall of the pharynx ; it can also raise 
 the larynx, and carry it backward. 
 
 The Middle Constrictor. 
 
 This is a membranous triangular muscle {v, figs. 141, 147), situated in the middle of 
 the pharynx, upon a plane anterior to the preceding. 
 
 It arises from the os hyoides, and is inserted into the posterior median raphe {hyo-pha- 
 ryngeus). It arises from the os hyoides in the following manner : 1. From the whole ex- 
 tent of the upper surface of the great comu below the hyo-glossus {t), from which it is 
 separated by the lingual artery ; a great many fibres arise by a tendinous origin from the 
 apex of this comu. 2. From the lesser comu and the contiguous part of the stylo-hyoid 
 ligament. From these difTerent origins, which form the external truncated angle of the 
 muscle, the fleshy fibres diverge in various directions ; the inferior passing downward, 
 the middle transversely, and the superior upward : the latter are much more oblique and 
 more numerous than the others, and terminate in a pointed extremity, which never reach- 
 es as high as the basilar process. 
 
 Relations. — Its external surface is in a great measure superficial, and is in relation with 
 the muscles of the prae-vertebral region, through the medium of the cellular investment 
 of the pharynx. It is covered, in the rest of its extent, by the inferior constrictor and 
 the hyo-glossus. It covers the mucous membrane of the pharynx, the superior constric- 
 tor, the stylo-pharyngeus, and the palato-pharyngeus. Its upper margin may be dis- 
 tinguished from the superior constrictor by its projecting slightly behind that muscle, and 
 by the stylo-pharyngeus (r), which lifts up this border in penetrating into the pharynx. 
 
 Action. — It is a constrictor of the pharynx, and can draw the os hyoides upward and 
 backward. 
 
 The Superior Constrictor. 
 
 This is a quadrilateral muscle {g,figs. 141, 147), occupying the upper part of the pha- 
 rynx ; it arises from the pterygoid process, the mylo-hyoid ridge, and the base of the 
 tongue, and is inserted into the posterior median raphe {pterygo-pharyngeus, buccinato- 
 pharyngeus, mylo-pharyngeus, and glosso-pharyngeus, Santorini). 
 
 It arises, 1. By tendinous fibres, from the lower third of the margin of the internal 
 pterygoid plate and its hamular process. 2. From the contiguous portion of the palate 
 bone, and the reflected tendon of the circumflexus palati. 3. From the buccinato-pha- 
 ryngeal aponeurosis, which extends from the pterygoid process to the posterior extrem- 
 ity of the inferior alveolar arch.* 4. From the posterior extremity of the mylo-hyoid 
 line. 5. The fibres which are said to arise from the base of the tongue are nothing 
 more than those fibres of the genio-hyo-glossus, which Winslow has described as le ge- 
 nio-pharyngien. These are the same fibres, so difficult to demonstrate, which Valsalva 
 and Santorini have regarded as forming a particular muscle, denominated by them the 
 glosso-pharyngeus. 
 
 From these different origins the fleshy fibres curve backward, and then pass trans- 
 
 * As this same aponeurosis gives attachment to the buccinator, it may be conceived that the contruction ot 
 that muscle cannot be altogether without effect upon the pharynx. 
 
^Ml SPLANCHXOLOGT. 
 
 versely inward ; the superior form a sort of arch, having its concavity directed upward 
 {see Jigs. 141, 147), and are inserted into the cephalo-pharyngeal aponeurosis : they form 
 the ccphalo-pharyngeus muscle of some authors, which is said to be continued from one 
 side to the other without any intermediate raphe. This muscle forms a very thin layer, 
 the fibres of which are paler and less distinct than those of the other constrictors. 
 
 Relations. — Its external surface is partly covered by the preceding muscle, and has be- 
 hind, and on the sides, the same relations as the pharynx. This muscle forms the inner 
 side of a triangular space already described (p. 345) (the maxillo-pharyngeal), the outer 
 side of which is formed by the ramus of the lower jaw and the internal pterygoid mus- 
 cle {b,fig. 141), and which is occupied by the internal carotid artery, the internal jugu- 
 lar vein, and the pneumogastric, h)T)0-glossal, and spinal accessory nerves. 
 
 Its internal surface (fig. 141) is in relation with the pharyngeal mucous membrane, 
 with the levator palati (c), which it separates from the circumflexus palati (d), and with 
 the palato-pharyngeus (c). 
 
 Action. — It is a constrictor. 
 
 Remarks. — From the preceding description, it follows, 1. That the constrictors of the 
 pharynx form three super-imposed or, rather, imbricated muscular layers. This imbrica- 
 tion, or overlapping, is so arranged that the projections (very slight, it is true) formed 
 by the upper margins of the constrictors are on the outer, not on the inner surface of 
 the pharynx ; and this has, perhaps, some relation to^he downward course of the ali- 
 mentary mass.* 2. That the thickest part of the muscular layer formed by the constric- 
 tors is opposite the buccal portion of the pharynx, where the lower and middle constric- 
 tors overlap ; and that the thinnest part is in the nasal portion, which is formed by the 
 superior constrictor alone. 3. That the pharyngeal insertions of all the constrictors are 
 upon a single line, the median raphe, while their points of origin are exceedingly nu- 
 merous, viz., commencing from below, the cricoid cartilage, the thyroid cartilage, the great 
 and lesser cornua of the os hyoides, the base of the tongue, the mylo-hyoid line, the buc- 
 cinato-pharyngeal aponeurosis, and, lastly, the pterygoid process. 
 
 The Extrinsic Muscles. 
 
 The extrinsic muscles of the pharynx are generally two in number, the stylo-pharyn- 
 geus and the palato-pharyngeus. The latter has been already described among the mus- 
 cles of the velum palati. It is by no means uncommon to find several supernumerary 
 muscles 
 
 The Stylo-pharyngeus. 
 
 This muscle (r, figs. 143, 147), which is round above and broad and thin below, arises 
 by tendinous and fleshy fibres from the inner side of the base of the styloid process, or, 
 rather, from the vaginal process surrounding that base. From this point it passes down- 
 ward and inward, becomes wider and flattened as it enters the pharynx between the 
 middle and superior constrictors, to spread out beneath the mucous membrane. Its up- 
 per fibres ascend, the middle are transverse, and the lower fibres descend to terminate 
 along the posterior border of the thyroid cartilage! (see jig. 143). These fibres, togeth- 
 er with those of the palato-pharyngeus, form the fourth muscular layer of the pharynx. 
 
 Relations. — Before entering the pharynx, the stylo-pharyngeus is in relation on the out- 
 side with the stylo-glossus muscle (u), the external carotid artery, and the parotid gland ; 
 on the inside, with the internal carotid and the internal jugular vein. Its most interest- 
 ing relation is with the glosso-pharyngeal nerve, which runs along its outer side. Some 
 branches of the nerve often pass through it. In the pharynx it is covered by the middle 
 constrictor, and it lies outside the superior constrictor, the palato-pharyngeus, and the 
 mucous membrane. 
 
 Actimi. — It raises the larynx and the pharynx. 
 
 Supernumerary Muscles of the Pharynx. 
 Among the supernumerary extrinsic muscles of the pharynx, I shall notice, 1. A fascicu- 
 lus pointed out by Albinus, which I have often met with : it arises from the petrous portion 
 of the temporal bone, and passes into the walls of the pharynx ; it is the petro-pharyn- 
 geus of some authors. 2. A very strong fasciculus, arising from the basilar process in 
 front of the foramen magnum, passing downward and inward, and interlacing with its 
 fellow of the opposite side in the median line : it may be called the occipito-pharyngeus. 
 3. A small muscle, which I have seen arising by well-marked tendinous fibres from the 
 summit of the hamular process of the internal pterygoid plate, passing obhquely inward 
 and downward, and expanding on the walls of the pharynx ; it may be called the extrin- 
 sic pterygo-pharyngeus. 4. Riolanus has described a spheno-pharyngeus arising from the 
 spinous process of the sphenoid, and Santorini and Winslow have noticed a salpingo-pha- 
 ryngeus arising from the cartilaginous portion of the Eustachian tube and the contiguous 
 bone, and blended in the pharynx with the palato-pharyngeus. » 
 
 * In the construction of pipes or tunnels for the conveyance of water, &c., each piece is received into that 
 below it ; an opposite arrangement would facilitate the blocking up of the pipe. 
 
 + Some anatomists affirm that they have seen fibres from this muscle reaching the base of the tongue, the 
 epiglottis, and the os hyoides. 
 
SUPERNUMERARY MUSCLES OF THE PHARYNX. 349 
 
 Such, then, are the muscles of the pharynx. They are all, as we have seen, constric- 
 tors, and at the same time elevators, in consequence of their fibres rising to a greater 
 height internally upon the median line than they do externally ; the stylo-pharyngeus 
 alone can be regarded as a dilator. Indeed, dilatation is chiefly effected by the muscles 
 of the OS hyoides, by the action of which the larynx is carried upward and forward ; we 
 may, therefore, with Haller, consider them as extrinsic muscles of the pharynx. 
 
 Pharyngeal Mucous Membrane. — The muscular semi-canal of the pharynx is lined by a 
 mucous membrane continuous with the buccal and nasal mucous membranes on the one 
 hand, and with those of the larynx and oesophagus on the other. This membrane, which 
 is of a reddish colour, presents some peculiarities at different parts of its extent. Above, 
 near the basilar process, it is thick, and, as it were, fungous, and closely united to the 
 periosteum, from which, indeed, it cannot be separated ; in this region it is very liable 
 to become the seat of fibrous polypi. Near the posterior orifices of the nasal fossae and 
 the openings of the Eustachian tubes, it is, in some respects, similar to the pituitary 
 membrane.* It forms a sort of rim around the trumpet-shaped orifice of the Eustachian 
 tube, into which it is prolonged in a remarkable manner, gradually becoming thinner, 
 and at length continuous with the lining membrane of the cavity of the tympanum. This 
 continuity of the mucous membrane of the pharynx and Eustachian tube explains the 
 close sympathy between these parts, and also the deafness which so frequently follows 
 chronic sore throats and coryzae, in consequence of the obstruction of these tubes. 
 
 In its buccal portion it exactly resembles the mucous membrane, upon the lower sur- 
 face of the velum palati : the part covering the posterior surface of the larynx is pale, 
 and forms several folds. 
 
 The mucous membrane of the pharynx adheres to the subjacent muscles only through 
 the medium of very loose cellular tissue, which is never loaded with fat, nor infiltrated 
 with serosity. It is ■still less intimately adherent to the posterior surface of the larynx. 
 
 Its surface is raised by a great number of small glands, chiefly occupying the upper 
 part of the pharynx, near the posterior nares : we shall divide them into agglomerated 
 and solitary. Two agglomerated glands are always situated around the orifices of the 
 Eustachian tube ; they open upon the mucous membrane, either separately or together. 
 These glands are sometimes arranged in a line, sometimes in several parallel rows. 
 Haller believes that the salpingo-pharyngeus of Santorini and Winslow is nothing more 
 than a series of these glands united together by fibrous tissue. The solitary glands are 
 scattered over the whole extent of the pharynx. Lastly, the pharyngeal mucous mem- 
 brane is provided with a thin epithelium,! which can be easily demonstrated by macer- 
 ation and the action of acids. 
 
 Vessels and Nerves. — The pharynx receives a principal artery on each side, viz., the 
 inferior pharyngeal, a branch of the internal carotid. The superior pharyngeal branch 
 of the internal maxillary, and some small twigs from the palatine and the superior thy- 
 roid, complete its arterial system. 
 
 Its veins form a very considerable plexus around it (the pharyngeal venous plexus), and 
 terminate in the internal jugular and superior thyroid. The lymphatiXhessels are little 
 known ; they pass into the glands lying along the internal jugular vein. Its nerves are 
 very numerous, and form a remarkable plexus — the pharyngeal, which I regard as one 
 of the largest in the body. They are derived from two sources : 1 . From the cerebro- 
 spinal axis, viz., the pharyngeal nerve, a branch of the pneumogastric, which appears to 
 be principally distributed to the muscular layer ; the glosso-pharyngeal, which appears to 
 be chiefly destined for the mucous membrane ; and, lastly, some branches of the supe- 
 rior laryngeal and the spinal accessory. 2. From the ganglionic system, several large, 
 gray, and soft branches being distributed to it from the superior cervical ganglion. 
 
 This abundance of nerves, and also the sources from which they are derived, will 
 serve to explain, 1. The great sensibility of the pharynx, to which part we refer the 
 feeling of thirst, which some have, therefore, proposed to term the pharyngeal sense ; 
 2. The part which it performs in the perception of certain flavours, for example, those 
 of acids ; 3. The sympathy between the pharynx, the base of the tongue, and the stom- 
 ach ; 4. The feeUngs of constriction and strangulation, so common in the pharynx ; 5 
 The spasms with which it is affected in tetanus and hydrophobia ; and, 6. The nature 
 of the globus hystericus, &c.t 
 
 Development. — The development of the pharynx offers no remarkable phenomena •, 
 still, it is an exception to the general law of bilateral development, laid down by some 
 anatomists. 
 
 Uses of the Pharynx. — ^The pharynx is one of the principal organs of deglutition. It 
 
 * See note, infra. . 
 
 t [According to Dr. Henl6, the upper part of the mucous membrane of the pharynx is covered with a <^U** 
 *ed columnar epithelium, as far down as a horizontal line extending from the lowei border of the atlas to the 
 floor of the nasal fossa ; below that line the epithelium assumes the squamous form, and is not cihated. In 
 the Eustachian tube it is also columnar, and provided with cilia ; but in the cavity of the tympanum it is 
 squamous, and destitute of those organs.] , 
 
 i We cannot explain why the syphilitic virus has so serious a predilection for the mucous membrane ot the 
 pharynx. 
 
SPLANCHNOLOGY. 
 
 serves also for the passage of air in respiration, and as a tube for modulating the voice. 
 The importance of the pharynx in this last point of view, and the influence which its dif- 
 ferent degrees of shortening and constriction exercise upon the compass of the voice, 
 do not appear to me to have sufficiently engaged the attention of physiologists. 
 
 The CEsophagus. 
 
 Tlie (esophagus {olau, I will convey, and ^ayw, I eat) is a musculo-membranous canal, 
 an organ of deglutition, intended to convey the food from the pharynx into the stomach. 
 It occupies the lower part of the cervical region and all the thoracic region, and perfo- 
 rates the diaphragm, in order to terminate in the stomach. 
 
 Directions. — It is situated in the median line, resting against the vertebral column ; 
 its general direction is straight, for the food does not remain in it ; nevertheless, it pre- 
 sents several slight curves ; at its commencement it is exactly in the middle line, but 
 inclines somewhat to the left side in the neck ; in the upper part of the thorax it deviates 
 slightly to the right side, then again becomes median, and, lastly, inclines to the left, 
 where it passes through the diaphragm. The general direction of the oesophagus per- 
 mits the introduction of straight probangs into the stomach. The inflection which it 
 undergoes at its entrance into the thorax explains the reason why these instruments 
 are sometimes arrested opposite the first rib. 
 
 Dimensions. — The length of the oesophagus corresponds to the interval between the 
 pharynx and the stomach, i. e., the space between the fifth cervical vertebra, or the cri- 
 coid cartilage, and the tenth dorsal vertebra. In regard to its calibre, or diameter, the 
 oesophagus is the narrowest part of the alimentary canal. Its diameter is not uniform 
 throughout, the cervical portion* being certainly the narrowest ; and, therefore, foreign 
 bodies which are too large to pass through the alimentary canal, are generally arrested 
 in the neck. The widest portion of the oesophagus is its lower end. 
 
 The oesophagus is capable of a certain degree of dilatation, as is proved by the passage 
 of large foreign bodies for a considerable distance through it (Mim. d'Hivin, Acad. Roy. 
 de Chirurgie), sometimes even aa far as the stomach. That this dilatability, however, 
 is very limited, may be inferred from the pain caused by swallowing too large a morsel, 
 and also from the stoppage of foreign bodies in the gullet. Nevertheless, in some CEises, 
 from external pressure upon, or from stricture of, some part of this canal, it becomes 
 greatly enlarged above the seat of obstruction, and forms a sort of ampulla or dilatation 
 resembling the crop in gedlinaceous birds. In one case I found a sort of pouch, or di- 
 verticulum, of the mucous membrane, of considerable size, protruding between the sep- 
 arated muscular fibres, and at first sight resembling the crop of gallinaceous birds. An 
 example has been recorded of dangerous suffocation occasioned by the pressure of ali- 
 mentary matters in a cavity of that kind. 
 
 Figure. — The oesophagus is cylindrical, and differs from the rest of the alimentary 
 canal in never containing any air, so that (when at rest) its parietes are always in con- 
 tact. It is somewhat flattened, and, as it were, compressed, at its upper part ; but be- 
 low it always pre|pnts the appearance of a solid cylinder, or a dense firm cord. This 
 appearance exists through its whole extent in some animals, the horse, for example. 
 
 Like all hollow organs, the oesophagus presents two surfaces, an external and an in- 
 ternal. 
 
 The external surface. In its long course the oesophagus has many relations, all ol 
 which are of great importance, and must be examined in the neck, in the thorax, and in 
 the abdomen. 
 
 In its cervical portion (y. Jigs. 1 14, 140), the oesophagus is in relation in front with the 
 membranous portion of the trachea {x), beyond which it projects a little on the left side. 
 The cellular tissue uniting these two canals is most condensed above. All that portion 
 which projects beyond the trachea comes into relation with the left sterno-thyroid muscle 
 (71, fig. 1 14), the thyroid body {z), the left recurrent laryngeal nerve, and the inferior thy- 
 roid vessels, which cross it at right angles. The relation of the oesophagus to the tra- 
 chea explains how foreign bodies arrested in the former passage may compress the tra- 
 chea, and impede or even prevent respiration. The deviation of the oesophagus to the 
 left is the reason for selecting that side for the performance of oesophagotomy. Behind, 
 it corresponds to the longi colli muscles and to the vertebral column, being united to 
 them by loose cellular tissue, so that it is enabled to execute those movements which 
 are necessary for the performance of its functions. Laterally, it corresponds to the thy- 
 roid body, the common carotid artery, and the internal jugular vein ; but these relations 
 are somewhat modified on each side, in consequence of the deviation of the oesophagus. 
 Thus, the relations of the oesophagus with the left common carotid are much more im- 
 mediate than those with the right. The left recurrent nerve lies in front of the oesopha- 
 gus, the right nerve a Uttle behind it. 
 
 Its thoracic portion (o, fig. 161) is situated in the posterior mediastinum, and is in rela- 
 tion in front, commencing from above, with the trachea, then with its bifurcation, and 
 slightly also with the left bronchus, which crosses it obliquely, and which may be com- 
 
 * [Opposite the cricoid cartilage.l 
 
THE OESOPHAGUS. 351 
 
 pressed by it during the retention of a foreign body (an example of this accident has been 
 recorded by Habicot) ; lastly, it is situated opposite and behind the ascending portion of 
 the arch of the aorta, and the base and posterior surface of the heart, from which parts 
 it is separated by the pericardium. Behind, it is in relation with the longus colli and the 
 vertebral column, to which, however, it is not so closely applied as in the neck ; nor does 
 it follow the curvature of the spine in the dorsal region, but is separated from it by a 
 space filled with cellular tissue, lymphatic glands, the vena azygos, and the thoracic duct, 
 the latter being placed to its right side, at the lower part of the thorax, but passing be- 
 hind it above, so as to reach the left side. Below, at the point where the oesophagus 
 deviates to the left side, in order to gain the opening of the diaphragm, it lies in front of 
 the aorta. On each side it forms a projection along the wall of the mediastinum, which 
 is thus brought into relation with the corresponding lung ; it is much more prominent on 
 the right than on the left side. On the left side it is also in contact, in its entire extent, 
 with the thoracic aorta (h,fig. 161), which is situated a little behind it. Above, it has 
 immediate relations with the arch of the aorta, as that vessel is passing backward and 
 to the left side of the vertebral column. It is commonly, at this point, that aneurisms 
 of the aorta open into the oesophagus. 
 
 In all this region the oesophagus is enveloped by a serous cellular tissue, extremely 
 loose and very abundant ; it is surrounded by a great number ofljrmphatic glands, which 
 have been improperly named oesophageal. These glands, when enlarged, sometimes 
 compress the gullet so much as completely to arrest deglutition. Lastly, the two pneu- 
 mogastric nerves run along each side of the oesophagus ; inferiorly the left comes in front, 
 and the right retires behind the canal : they communicate with each other throughout 
 their course by loops or arches, which, perhaps, explains the pain caused by swallowing 
 too large a mass of food. 
 
 In its abdominal portion (if such can be said to exist), the oesophagus is in relation with 
 the oesophageal opening of the diaphragm, below which it is entirely covered by the 
 peritoneum. On the right side and in front it is embraced by the left extremity of the 
 liver ; behind, by the lobulus Spigelii. In some subjects the abdominal portion of the 
 oesophagus is an inch in length, but this, I think, is occasioned by descent of the stomach. 
 
 The internal surface is remarkable for its pale colour, which contrasts strongly with the 
 rosy hue of the stomach and the upper part of the pharynx, for the vsTinkling of its pa- 
 rietes and their contact with each other, and, lastly, for its longitudinal folds, which 
 seem to have reference to the necessity for its momentary distension during the mere 
 passage of the food through it. 
 
 Structure. — The oesophagus is essentially composed of two cyhndrical membranes, one 
 internal or mucous, the other external or muscular. 
 
 The muscular coat is remarkable for its thickness, which greatly exceeds that of any 
 other part of the alimentary canal, and is connected with the necessity for the rapid pas- 
 sage of the alimentary mass from the pharynx into the stomach. It is susceptible of hy- 
 pertrophy, as we find in cases of stricture of the lower part of the gullet. I have seen 
 it five or six lines thick. In all herbivorous animals in which the oesophagus is almost 
 incessantly in action, in those in which the food is carried upward in opposition to grav- 
 ity during the act of deglutition, in the horse and in ruminants, the muscular coat is still 
 more developed than in man. 
 
 The muscular coat is of a red colour immediately below the pharynx, and rosy through 
 the rest of its extent, but of a darker tint than in the succeeding portion of the aliment- 
 ary canal. It is of a vivid red in herbivora.* 
 
 This coat is composed of two very distinct layers, the external consisting of longitu- 
 dinal fibres regularly disposed upon all sides of the oesophagus ; the internal, of circular 
 fibres, in which we shall in vain seek for the spiral arrangement described by some anat- 
 omists as existing in animals and in man.t The longitudinal fibres seem to arise, at 
 least in part, from the posterior surface of the cricoid cartilage, in the median line, be- 
 tween the two posterior crico-arytenoid muscles ; they evidently become continuous be- 
 low with the longitudinal muscular fibres of the stomach. The first muscular ring of the 
 oesophagus appears to arise from the cricoid cartilage ; it has been designated the crico- 
 msophageus. There is no sphincter, as some anatomists have affirmed, round the lower 
 extremity of the oesophagus. 
 
 The Mucous Membrane. — As Bichat has remarked, the mucous membrane of the oesoph- 
 agus is, perhaps, next to the buccal, the thickest in the alimentary canal. By a remark- 
 able exception (also observed in the rectum), its outer surface is united to the adjacent 
 membrane by a very loose cellular tissue ; so that the whole mucous cylinder may be 
 removed entire from the sort of muscular sheath in which it is contained. It has even 
 been said that the muscular coat can force the mucous membrane downward by its con- 
 traction, so as to produce a projecting rim around the cardiac orifice of the stomach, 
 jmalogous to that which is formed at the anus in prolapsus. The longitudinal folds of 
 
 * [It consists of involuntary muscular fibres (note, p. 323), intermixed with fibres possessing transverse stnte.] 
 i [These fibres are obviously spiral in the ruminant, and many other mammalia ] 
 
352 
 
 SPLANCHNOLOGY. 
 
 the mucous membrane are not caused by the contraction and elasticity of the circular 
 fibres of the muscular coat, but depend upon a peculiarity of structure. If the first hy- 
 pothesis be correct, why should not the mucous membrane also present transverse folds 
 from the action of the longitudinal fibres \ for the extremities of the oesophagus are not so 
 fixed, nor is its tension so great that it could not be shortened by the action of these fibres. 
 
 Besides the longitudinal folds, there are also in the oesophagus a number of wrinkles 
 analogous to those of the skin, and, therefore, irregular ; they appear to me to be caused 
 by the elasticity of the muscular fibres. 
 
 The mucous membrane of the oesophagus has a thick epithelium, which may be easily 
 shown by maceration and the action of acids, or even without preparation, and which 
 terminates at the cardiac orifice of the stomach by an irregularly fringed or festooned 
 border.* 
 
 When examined by the microscope, the free surface of the mucous membrane pre- 
 sents a number of small linear ridges, running vertically, and united together by other 
 oblique ridges, so that the whole surface has a reticulated aspect. These ridges are 
 formed by papillae or villosities, the arteries and veins of which have been accurately 
 figured by Bleuland. 
 
 The surface of the mucous membrane is raised in various places by small, oblong, and 
 flat glands found here and there over the entire oesophagus. They were first described 
 by Steno, and should be carefully distinguished from the oesophageal lymphatic glands : 
 the latter are external to the oesophagus, and, in certain animals, frequently contain small 
 entozoa : they have been supposed to open into the oesophagus, and to deposite within it 
 a fluid containing these animalcules, which some physiologists have regarded as the 
 chief agent in digestion. Any communication, however, between these lymphatic glands 
 and the cavity of the gullet is purely accidental. The true oesophageal glands are very 
 numerous.! 
 
 In the oesophagus, there is only a trace of the fibrous membrane, which forms the frame- 
 work of the alimentary canal ; it adheres to the muscular coat, and is, therefore, but 
 loosely attached to the mucous membrane. 
 
 There is no external serous membrane ; it would not have yielded to the instantane- 
 ous dilatation required in the cesophagus. The two laminse of the posterior mediasti. 
 num corresponding to its sides may be regarded as forming the rudiment of a serous coat. 
 
 Vessels and Nerves. — The (esophageal arteries are numerous, and arise from several 
 sources. They may be distinguished into the cervical, proceeding from the inferior thy- 
 roid ; the thoracic, given off either directly from the aorta or from the bronchial and in- 
 tercostal arteries, and sometimes from the internal manmiary ; and, lastly, the abdominal, 
 arising from the coronary artery of the stomach, and the inferior phrenic. 
 
 The vei7is terminate in the inferior thyroid, the superior cava, the azygos, the internal 
 manunary, the bronchial, the phrenic, and the coronary of the stomach. 
 
 The lymphatic vessels enter the numerous glands which surround the oesophagus. 
 
 The 7ierves are very numerous, and are derived from the pneumogastrics, which sur- 
 round the oesophagus with a series of loops ; these are joined by some branches from the 
 thoracic ganglia oi the sympathetic. 
 
 The development of the cesophagus presents nothing worthy of notice. 
 
 Functions. — The cesophagus is intended to convey the food rapidly from the pharynx 
 to the stomach. This function is performed by its longitudinal fibres shortening the pas- 
 sage, and by its circular fibres contracting it successively from above downward during 
 deglutition ; in vomiting or regurgitation, the contraction proceeds from below upward. 
 
 Fig. 148. 
 
 The Stomach. 
 
 The stomach {yaarfip, ventriculus), one of the princi- 
 pal organs of digestion, is that wide dilatation {s, fig. 
 139) of the ahmentary canal, intervening between the 
 cesophagus (a) and the duodenum (i c), in which the 
 food is collected and converted into chyme. 
 
 Situation. — It is situated at the junction of the upper 
 tenth with the lower nine tenths of the alimentary ca- 
 nal, between the organs of deglutition and those of 
 chylification. It occupies the upper part of the abdom- 
 inal cavity («, figs. 155, 161), almost entirely fills the 
 left hypochondrium, and advances into the epigastri- 
 um, as far as the limits of the right hypochondrium.i: 
 
 * [The epithelium is, in fact, continued on through the rest of 
 the alimentary canal, but becomes thinner, and assumes a different 
 character : in the cesophagus it is squamous.] 
 
 t [Especially around the lower extremity of the gullet.] 
 t [In order to facilitate the description of the viscera contained 
 in the abdominal cavity, anatomists have adopted the following ar- 
 tificial division of that cavity into several regions : The abdomen 
 is first divided into three zones by two horizontal lines, one (o a 
 
THE STOMACH. 353 
 
 It is maintained in its place by the oesophagus and duodenum, and also by some folds 
 of the peritoneum, which connect it with the diaphragm, the hver, and the spleen. The 
 stomach is, therefore, less subject to displacement than most of the abdominal viscera. 
 It may even be generally stated, that almost all the changes in the relative situation ol 
 this organ are the results of displacements or alterations in the size of those organs 
 which are connected with it. I do not here refer to examples of complete transposition 
 of the viscera, nor to those cases of malformation of the diaphragm, in which the stom- 
 ach has been found in the thorax. 
 
 Direction. — The stomach is directed obliquely downward to the right side, and a little 
 forward ; this direction affords some explanation of the almost constant habit of lying 
 on the right side during sleep, and why the rest is disturbed and digestion rendered diffi- 
 cult in those who lie upon the left side. Changes in direction of the stomach depend 
 upon the same causes as changes in its situation. Thus, dragging produced by displace- 
 ment of the small intestine or the omentum, enlargements of the liver or spleen, or the 
 use of too tight stays,* must necessarily affect the direction of this organ. We not un- 
 frequently find stomachs having a vertical direction. 
 
 Number. — The stomach is single in the human subject as well as in the greater num- 
 ber of animals. The examples of double or triple stomachs in the human subject are 
 merely cases of single stomachs having one or more circular constrictions. t The es- 
 sential character of a double stomach is not an accidental or even a congenital contrac- 
 tion, but a difference in structure. Bilocular stomachs, indeed, are very common ; but 
 this form (resembling that of some kinds of calabash-gourds), though sometimes extreme- 
 ly well marked when the stomach is empty, disappears ahnost entirely when it is much 
 distended by inflation. 
 
 Size. — In all animals, the stomach is the most capacious part of the alimentary canal ; 
 so that, in many species, where its limits are not so clearly defined as in man, the ex- 
 istence of a stomach is determined only by the presence of a dilatation. It is of consid- 
 erable size in herbivora, but comparatively much smaller in camivora. The human 
 stomach is intermediate between these extremes — a fact which affords evidence of its 
 adaptation to both vegetable and aliment diet. The human stomach, however, presents 
 innumerable varieties in size, from a state of extreme contraction, in which it scarcely 
 exceeds the duodenum, to such an enormous degree of dilatation that it occupies a third, 
 a half, or even almost the whole, of the abdominal cavity. These differences depend 
 less upon original variations, than upon its peculiarly dilatable and elastic structure, 
 which enables it to contain a large quantity of food, and to contract more or less com- 
 pletely upon itself when empty. Thus, the stomach has a much greater capacity in those 
 who adopt the bad habit of eating only one very full meal in the twenty-four hours, than 
 in those who eat more frequently, but less abundantly. In some cases of stricture at the 
 pylorus, it becomes enormously distended. Long-continued abstinence occasions such 
 an amount of contraction, that it has even been asserted, that pain resulting from the 
 rubbing of its parietes together gives rise to the feeling of hunger ; but this completely 
 mechanical hypothesis should be rejected. In a great number of cholera patients, the 
 stomach was found to be exceedingly small. In a female, who died a month after hav- 
 ing voluntarily swallowed a small quantity of sulphuric acid, the contracted stomach was 
 not larger than a moderately-sized gall-bladder. 
 
 Figure. — The stomach resembles a flattened cone, curved upon itself backward and 
 upward, and having a rounded base ; it has been compared to the bladder of a bagpipe. 
 Sections made at right angles to its axis represent circles gradually decreasing in size 
 from the entrance of the oesophagus to the pylorus. We have to examine its external 
 and its internal surface. 
 
 The external surface. From the peculiar form of the stomach, we are enabled to con- 
 sider an anterior and a posterior surface, a convex border or great curvature, and a con- 
 cave border or lesser curvature, a great cul-de-sac or tuberosity, an oesophagal extremi- 
 ty, cuid a pyloric extremity. 
 
 The anterior surface (upper surface of some anatomists, s,Jig. 155) is directed forward, 
 and a little upward. When inflated in the dead body with the abdomen open, it is turn- 
 ed directly upward ; but such cannot take place, either in the living or dead subject, 
 
 fig. 148) extending between the most prominent points of the cartilages of the ribs, and the other {f> b) be- 
 tween the crests of the iliac bones. The superior zone is called the epigastric ; the middle, the umbilical ; 
 and the inferior, the hypogastric. These three zones are then subdivided by two vertical parallel lines drawn 
 from the cartilages of the eighth rib down to the centre of Poupart's ligament. The epigastric zone is thus 
 divided into two hypochondriac (1 Ij^and a middle epigastric region (2) ; the umbilical into two lumbar (3 3), 
 and a middle umbilical region (4) ; and the hypogastric into two iliac (5 5), and a middle hypogastric region (6).] 
 
 * It is impossible to insist too strongly upon the influence of too tight stays on the situation, and even the 
 form, of the viscera occupying the base of the thorax. Thus, changes in the situation and direction of the 
 stomach are much more frequent in females than in males. Soemmering observed, but without stating the 
 cause, that the stomach is more rounded in the male, and more oblong in the female. 
 
 t It may, strictly speaking, be stated that ruminants have only one stomach, the rennet or obomasum; and 
 that the iirst three, viz., the paunch, the reticulum, and the manypHes or omasum, are nothing more than dila- 
 tations of the oesophagus, in which the food undergoes a preparatory elaboration. The same observation ap- 
 plies to birds, in which the crop and the gizzard are not organs of chymification, the first being merely an or- 
 ?ar of insalivation, the second one of trituration. 
 
 Yy 
 
364 SPLANCHNOLOGY. 
 
 when the abdominal parietes are entire ; in which case the distended stomach passes in 
 the direction of the least resistance, i. e., forward and downward, and its anterior sur- 
 face cannot then be completely turned up. 
 
 This surface is in relation with the diaphragm, and is separated by it from the heart ; 
 with the liver, which is prolonged upon it to a greater or less extent ;* with the last six 
 ribs, being separated from them by the diaphragm ; and with the abdominal parietes in 
 the epigastrium : hence the name given to that region. It is not uncommon to find the 
 great omentum turned upward between the stomach and the liver. When distended, 
 the stomach has much more extensive relations with the epigastrium, or, rather, with 
 the abdominal parietes, both in a vertical and transverse direction. 
 
 All these relations are of the greatest importance ; and, with the exception of those 
 which concern the epigastrium, they are constant. In fact, it rarely happens that the 
 stomach precisely corresponds to the sub-sternal or xiphoid depression, which has been 
 called the pit of the stomach, or the scrobiculus cordis, but which belongs neither to the 
 heart nor the stomach. In exploring this depression, it is almost always the liver wliich 
 is felt ; the stomach lies lower down, and is generally below the ensiform appendix. 
 
 The posterior surface {inferior surface of some anatomists, seen turned up at s,fig. 154) 
 is directed downward and backwjurd, and is seen in the sac of the omentum, of which 
 it forms the anterior wall. 
 
 It has relations with the transverse mesocolon, which serves as a floor for it, and sep- 
 arates it from the convolutions of the small intestines ; with the third portion of the duo- 
 denum (e' to b), by some of the older anatomists called the pillow of the stomach {ven- 
 triculi pulvinar) ; and, lastly, with the pancreas (o). The duodenum, the pancreas, the 
 aorta (a), and the pillars of the diaphragm {d d), separate it from the vertebral column, 
 upon which it rests obUquely. These relations are modified by the emptiness or fulness 
 of the stomach. 
 
 The great curvature (the inferior or anterior border of some anatomists, cad, fig. 149) 
 Fig. 149. is convex, and directed almost vertically downward 
 
 in the empty condition of the organ, and almost di- 
 rectly forward when it is full ; it gives attachment 
 to the two anterior layers of the great omentum. It 
 is in relation with the abdominal parietes and the 
 cartilages of the lower ribs, and lies along the trans- 
 1^ verse arch of the colon (,t,Jlg. 155), in front of which 
 it advances when considerably distended ; hence it 
 was termed the colic border by Chaussier. In the 
 distended state its relations with the abdominal pa- 
 rietes become much more extensive ; but even then I 
 can scarcely believe the assertions of some, that the 
 pulsations of the gastro-epiploic arteries can be felt by the finger in emaciated individuals. 
 The lesser curvature (the superior or posterior border of some anatomists, o b p, fig. 149) 
 is concave, and extends from the oesophageal orifice to the pylorus ; it gives attachment 
 to the small or gastro-hepatic omentum ; it is directed upward when the viscus is empty, 
 upward and backward when it is full ; and it then embraces the vertebral column in its 
 curvature, being separated from it by the aorta and the pillars of the diaphragm (see^^. 
 154) ; it also embraces the small lobe of the liver or the lobulus Spigehi, the coeliac axis 
 (f), and the solar plexus of nerves. 
 
 The great extremity or great cul-de-sac of the stomach (the bottom or great tuberosity, from 
 c to the dotted line, fig. 149) comprises all that portion which is to the left of the car- 
 diac or cEsophageal opening ; it is a sort of semi-spheroid, applied to the base of the cone 
 formed by the rest of the stomach ; it is the highest and the largest portion of that or- 
 gan ; it is almost entirely absent in carnivora ; it is very large in herbivora, and of a 
 medium size in man. There are also many individual varieties in the size of this por- 
 tion of the stomach ; I have met with some instances in which it W2is not larger than it 
 is in carnivora. 
 
 It is in contact with the spleen {k, fig. 154) (hence it is called the splenic extremity by 
 Chaussier), with which it is connected by a fold of the peritoneum, called the gastro- 
 splenic omentum, and by the vasa brevia. When the stomach is distended it comes into 
 close contact with, and is, as it were, moulded upon, the spleen (see fig. 161). From this 
 relation a great number of physiological inferences may be deduced. t The great cul- 
 de-sac occupies the left hypochondrium, and corresponds also, in the greater part of its 
 
 * The relations of the anterior surface of the stomach with the liver are very variable in extent ; it some- 
 times reaches even to the gall-bladder. I have seen a case in vphich the gall-bladder adhered to the anterior 
 surface of the stomach, and, therefore, to the left of the pylorus, and communicated with it by an orifice, through 
 ■which bile and biliary calculi were discharged. 
 
 t The great end of the stomach is so closely connected with the spleen, that it necessarily follows all dis- 
 placements of that organ. I have met with a case in which the spleen, three or four times its natural size, 
 ■was situated in the umbilical region, and had dragged down the great end of the stomach with it. The left 
 extremity of the transverse colon, and the upper part of the descending colon, occupied the place of the great 
 extremity of the stomach. The patient had long suffered from indigestion, which had been attributed to chron- 
 ic gastritis. 
 
THE STOMACH. 355 
 
 extent, to the left half of the diaphragm, which is in accurate contact with it, and separ- 
 ates it from the lungs above and from the last six ribs in front. It is more or less ele- 
 vated, according to the degree of distension of the stomach ; and from this we can easi- 
 ly understand that difficult respiration may be caused by too large a meal. 
 
 Lastly, it may be stated that the great extremity of the stomach has relations behind 
 with the pancreas, and with the left kidney and supra-renal capsule. 
 
 The (Esophageal extremity (o, Jig. 149). The oesophagus opens into the stomach at 
 different angles, according to the emptiness or fulness of that organ. The situation of 
 this opening, which is improperly denominated the cardia {cor, heart), is at the left ex- 
 tremity of the lesser curvature, to the right of the great cul-de-sac, and opposite the 
 (Esophageal opening in the diaphragm. It is embraced (c. Jig. 154) in front by the left 
 extremity of the liver, which sometimes forms a half circle round it, and behind by the 
 lobulus Spigelii. It is surrounded by a circle of vessels and some nerves. Examined 
 externally, the lower end of the oesophagus is continuous with the stomach, without any 
 other line of demarcation than that depending upon a difference in size and direction. 
 The peritoneum is directly reflected from the diaphragm upon the oesophagus and the 
 stomach, and forms the gastro-diaphragmatic fold (ligamentum phrenico-gastricum. 
 ScBJnmerifig).* 
 
 The pyloric extremity {pylorus, from ttCIt], a gate, and o^pof, a keeper, p,figs. 149, &c.) 
 iS situated at the right extremity of the stomach. It forms the apex of the cone, and 
 presents a circular constriction or strangulation, which exactly defines the limits between 
 the stomach and duodenum. About an inch from this constriction the stomach is much 
 curved, so as to form a decided bend, and presents a dilatation, on the side of the great 
 curvature corresponding to an internal excavation, called by Willis the antrum pylori, and 
 by others the srnall cul-de-sac of the stomach (from d to the dotted line e). Not uncom- 
 monly we find a second dilatation near the first, and a third, still smaller, on the side of 
 the lesser curvature, resulting from the bend formed by the stomach. The pyloric ex- 
 tremity of the stomach is directed to the right side, backward and upward, and some- 
 times even a little to the left, when the stomach is much distended. 
 
 The relations of the pyloric extremity with the abdominal parietes are very variable, for 
 the changes in the situation of the stomach chiefly affect this extremity. It corresponds 
 to the liaiit between the epigastrium and the right hypochondrium ; sometimes it is in 
 relation with the gall-bladder, and hence may become stained ; in some cases it passes 
 to the right of the gall-bladder, to the extent of an inch or an inch and a half. I have 
 seen it occupying the horizontal fissure of the hver, the edges of which were separated 
 for its reception. Very commonly we find the pylorus in the umbilical region. I have 
 seen it in the hypogastrium in a female who was affected vdth schirrus of the pylorus, 
 and I have also found it in the right iliac fossa. It is, therefore, extremely difficult to 
 determine the seat of an organic lesion of the pylorus from external examination. 
 
 The relations of the pylorus with the abdominal viscera are more constant : above, it 
 corresponds to the liver and the lesser omentum ; below, to the great omentum ; in front, 
 to the abdominal parietes ; and behind, to the pancreas. It is not uncommon to find it 
 adhering to the gall-bladder. # 
 
 The Internal Surface. — This presents the same regions as the external surface ; all its 
 peculiarities may be referred to the raucous membrane, which will be noticed when the 
 structure of the stomach is described. Besides these, however, we observe here the 
 two orifices of the stomach. 
 
 The oesophageal orifice (cardiac, left, or superior orifice, ostium iiitroitus, o, Jig. 150) is 
 remarkable for its radiated folds (ad steUae similitudi- pj UO 
 
 nem. Holler), which are effaced by distension ; for the ^, 
 
 irregularly fringed border and the change in colour ^ ,• , ? \ 
 
 which mark the limits between the mucous membrane 
 of the oesophagus and of the stomach ; for its size and 
 its capabihty of dilatation ; and, lastly, for the total ab- 
 sence of any valve or sphincter. 
 
 The duodenal or pyloric orifice (right or anterior ori- 
 fice, janitor, sphinctor, ostium, exitus, p) is remarkable 
 for an internal rim, or circular valve, which in a distend- 
 ed and dried stomach forms a sort of diaphragm (in 
 speciem diaphragmatis, quedia sunt in tubis telescopicis, Morgagni) ; for the narrowness 
 of the passage, which, with difficulty, admits the little finger in most subjects ; for its slight 
 dilatability ; and, lastly, for the existence of a muscular ring, which may be regarded as 
 a true sphincter. It is of importance to remark, that this orifice, independently of ajiy 
 disease, presents a great number of varieties in its dimensions, and it is probable that 
 these congenital or acquired variations may have some influence upon its diseases. 
 
 The relative position of these two orifices is an important anatomical point. Upon 
 this we should observe, 1. That they are but little apart from each other, considering 
 
 * [Hence this extremity is comparatively fixed.] 
 
356 
 
 SPLANCHNOLOGY. 
 
 the size of the stomach, and that the interval between them does not increase in propor- 
 tion to that size ; 2. That the oesophageal orifice is directed upward, the pyloric open- 
 ing backward and a little upward ; 3. That the two openings are not upon the same plane, 
 the oesophageal being higher and more posterior than the pyloric. 
 
 The Structure of the Stomach. — In order to study the structure of the stomach, it is 
 necessary, in the first place, to distend it. Two stomachs are indispensable for this pur- 
 pose, one to be dissected from without inward, and the other from within outward. 
 One of the stomachs should be everted, and then inflated. 
 
 The parietes of the stomach are formed by the super-position of four membranes or 
 coats, differing in texture and properties. These, proceeding from without inward, are 
 the serous, the muscular, the fibrous, and the mucous coats. We must also examine the 
 vessels, nerves, and cellular tissue, which enter into the composition of these parietes. 
 
 1. The serous or ■peritoneal coat. Like almost all the movable viscera of the abdomen, 
 the stomach receives a complete covering from the 'peritoneum {membrana communis of 
 the ancients ; la membrane capsulaire, Chauss.). It is formed in the following manner : 
 Two layers of the''peritoneum, in contact with each other, pass from the transverse fis- 
 sure of the liver to the lesser curvature of the stomach : there they separate, so as to 
 leave between them a triangular space, the base of which corresponds to the lesser curva- 
 ture ; the anterior layer then passes over the anterior surface of the stomach, and the pos- 
 terior covers it behind ; they again approach each other at the great curvature, along which 
 they form another triangular space, exactly resembling that which we have already de- 
 scribed as existing at the lesser curvature, and then unite so as to form the two ante- 
 rior layers of the great omentum (see description of Peritoneum). The same airange- 
 ment takes place at the great extremity of the stomach. Bloodvessels pass round the 
 stomach, along the line where the two layers of the peritoneum are applied to each oth- 
 er at its two curvatures. 
 
 The peritoneum, therefore, forms a complete covering for the stomach, excepting at 
 the curvatures, where we find triangular spaces, into which the stomach is forced during 
 its distension. I doubt whether these triangular spaces can afibrd sufficient space for 
 the stomach when greatly distended, and I believe that, in such cases, the two anterior 
 layers of the great omentum separate, and are applied upon that organ. It is evident, 
 besides, that distension of the stomach chiefly affects its great curvature. 
 
 The peritoneal coat does not adhere firmly to the subjacent tissues of the stomach, in 
 the neighbourhood of either curvature ; but it is closely united to them at the middle points 
 of both surfaces. The imperfect extensibility of the peritoneal coat requires such an ar- 
 rangement as exists along the curvatures. I have observed some small fibrous bands 
 in the sub-serous cellular tissue along the lesser curvature, which must be intended to 
 maintain the shape of that part. The uses of the peritoneal coat, in reference to the 
 stomach itself, are merely mechanical ; it strengthens, preserves the shape, and facili- 
 tates the movements of this organ. 
 
 The Muscular Coat. — This coat has engaged much of the attention of anatomists since 
 the time of Fallopius, who was the first to give a correct description of it ; and to whom 
 Morgagni {Advers. Anat., iii., p. 6) has^ttributed the honour of discovering it, in opposi- 
 tion to the claims of Willis. Helvetius made it the subject of a special work {Hist. 
 Acad. Roy. des Sciences, 1719). 
 
 We shall describe, in accordance with Haller (Elem. Phys., tom. vi., lib. xix., sect, i., 
 
 Fig. 161. 
 
 p. 126), and the majority of anatomists, three layers of muscu- 
 lar fibres. 
 
 The superficial or longitudinal layer (1, fig: 151) is formed by a 
 continuation of the longitudinal fibres of the oesophagus, whioh 
 spread out in a radiated manner from the cardiac orifice of the 
 stomach. They are scattered thinly over its surfaces, the great 
 curvature, and the great extremity, but are collected into a band 
 along the lesser curvature, the shape of which they assist in 
 preserving. On account of this arrangement, they have re- 
 ceived the name of cravatc de Suisse. 
 
 These fibres form a continuous plane of considerable thick- 
 ness over the contracted portion of the stomach, near the pylo- 
 rus. In this situation they are stronger, and fasciculated, and 
 appear partly to terminate in the pyloric constriction, and part- 
 ly to be continued upon the duodenum. 
 
 The second or circular layer (2, fig. 151) is composed of fibres 
 which cross the axis of the stomach at right angles, so as to 
 form a succession of rings from the oesophagus to the pylorus. 
 They are few in number at the great extremity of the stomach, 
 but become much more numerous towards the pylorus, through- 
 out all the contracted portion of the stomach. At the pylorus 
 itself they form a thick ring, which forms a sort of rim, project- 
 ing in the interior. I have always found this more developed 
 
THE STOMACH. 357 
 
 in old age than at any other period of life. It is a true sphincter, which, by its contrac- 
 tion, effectually opposes the passage of food and gas from the stomach into the duode- 
 num. It is not uncommon to find the whole of this ring, or a half, or two thirds of it, in- 
 creased to the thickness of three or four lines, independently of any organic lesion. 
 
 The older anatomists admitted also an oesophageal ring (or (esophageal sphincter), simi- 
 lar to that at the pylorus, and having the power of closing the oesophageal orifice. This, 
 however, does not exist ; the last circular fibres of the oesophagus do not form a thicker 
 layer than the others. 
 
 Lastly, the different rings formed by the circular fibres of the stomach intersect each 
 other obliquely at very acute angles. The spired arrangement admitted by Santorini 
 cannot be demonstrated. 
 
 The third muscular layer (3, fig. 151), which I have only been able to see distinctly upon 
 hypertrophied stomachs, is composed of looped or parabolic fibres, the middle portions of 
 which embrace the great end of the stomach, extending from the left side of the cardiac 
 orifice obliquely downward towards the great curvature, while their anterior and posterior 
 extremities are situated upon the corresponding surfaces of this viscus. The superior 
 loops reach the lesser curvature, the inferior the great curvature, and the intermediate 
 loops seem to be lost upon either surface, or, rather, to become blended with the circu- 
 lar fibres. This layer of fibres appears intended to compress the great extremity of the 
 stomach, and to push the food into the body of the organ, towards the pylorus. 
 
 From what has been stated, it follows that, excepting in the vicinity of the pylorus, 
 the muscular layers of the stomach do not form a continuous plane, but have an areolar 
 disposition : the areolae, or spaces between the different fibres, are of considerable size ; 
 hence the necessity for a strong membrane, like the fibrous coat, which, as we shall 
 find, constitutes the framework of the stomach. 
 
 The muscular fibres of the several layers are much paler than those of the oesopha- 
 gus.* They have a pearly appearance when seen through the peritoneal coat, which 
 has led to the supposition that they are tendinous. Hence the error of Helvetius, Wins- 
 low, and others, who regarded the two white lines running along the two surfaces of the 
 stomach, between the curvatures, as ligaments of the pylorus ; they are nothing more 
 than longitudinal muscular fibres. Other authors have merely admitted some tendinous 
 intersections of these fibres. 
 
 The muscular coat is not uniformly thick at all points. It is very thin at the great 
 cul-de-sac, and becomes much thicker towards the pylorus. It also presents many va- 
 rieties in different subjects ; it is but slightly developed in large stomachs, and much more 
 so when this organ is contracted. There is a physiological as well as a pathological hy- 
 pertrophy of the muscular coat. In the latter it has been found seven or eight lines thick. 
 
 The Fibrous Coat. — This coat, the existence of which has been alternately admitted 
 and denied, is situated between the muscular and the mucous coats, and is quite distinct 
 from both. It was known by the ancients as the membrana nervosa ,•+ it constitutes, 
 properly speaking, the frcmiework of the organ. In order to demonstrate this coat, it is 
 sufficient to remove the peritoneal and muscular tunics, and then to evert the stomach 
 and remove the mucous membrane. This experiment will also very clearly show the 
 great strength of the fibrous coat, which, even thus unsupported, can bear considerable 
 distension ; while, on the other hand, when this coat has been divided, the remaining 
 membrane or membranes burst through the opening thus made. 
 
 This coat should not be confounded with the dermis of the mucous membrane, for it 
 adheres much more strongly to the muscular coat, into which it sends numerous pro- 
 longations, than to the mucous membrane, with which it is connected only by loose cel- 
 lular tissue. 
 
 The fibres of this coat have not a parallel arrangement like those of aponeuroses and 
 fibrous sheaths, but they form a very dense network, the filaments or lamellae of which 
 can be separated by inflation or infiltration. It is concerned in a very important man- 
 ner in chronic diseases of the stomach ; it is very liable to hypertrophy ; and, in certain 
 cases, acquires a thickness of several lines. 
 
 The Mticous Membrane. — The history of this membrane is curious. It was for a long 
 time confounded with the mucus by which it is covered, being regarded as merely a dried 
 layer of that secretion.J It was pointed out by Fallopius, who applied to it the very ap- 
 propriate appellation of the velvet-like tunic ; but it was first described as a separate mem- 
 brane by Willis, under the title of the glandular tunic. The discovery was confirmed by 
 the beautiful injections of Ruysch, who gave it the name of epithelium ; to which term, 
 however, he did not attach the same meaning as modern authors. It was afterward re- 
 garded as an epidermic membrane, analogous to the epidermis of the skin,^ and capable 
 
 * [Thejr are principally of the involuntary class, but have a few striated fibres among- them (see note, p. 3 JJ 
 
 t [So called from its white appearance.] 
 
 X Riolanus states positively {Anthropol, 1. ii., c. xii., p. 171) that the stomach, like the intestines, is com- 
 posed of three coats, viz., a common external membrane, a nervous, and a muscular coat; and that a closely 
 adherent mucus, consisting of the thickest part of the chyle, lines it on the inside. 
 
 t) Such was the opinion of Ilaller, lib. xix. p. 132. 
 
358 SPLANCHNOLOGY. 
 
 of being thrown off and renewed. In recent times it has been supposed to be concerned 
 tanquam omnium lerna malorum, and has become in the present day the object of a great 
 number of most interesting researches. 
 
 The mucous membrane of the stomach presents an adherent and a free surface. The 
 adherent surface is united to the fibrous coat by cellular tissue, so loose as to permit very 
 free motions. The free surface has the following characters : When the stomach is 
 strongly contracted, it forms a number of folds (see^^. 150), the principal of which are 
 longitudinal ; these folds disappear when the organ is distended, as may be shown in an 
 everted stomach. Their only use is to allow of the rapid distension of this organ, a con- 
 dition that could not have been attained in any other mode, in consequence of the slight 
 elasticity of the mucous coat. 
 
 These longitudinal and temporary folds, which are perfectly distinct from the perma- 
 nent folds observed in other parts of the alimentary canal, are most strongly marked 
 near the pyloris ; they are extremely regular, sometimes straight and sometimes flexu- 
 ous ; and they proceed parallel to each other from the cardiac towards the pyloric orifice 
 They are intersected more or less obliquely by other winding folds of different degrees, 
 which often give an areolar appearance to the internal surface of the stomach. 
 
 From this arrangement, it follows that dilatation of the stomach occurs principally in 
 a direction across its long axis ; the resources for dilatation in the direction of its axis 
 are much less numerous. Of all the folds of the mucous membrane, the most important 
 is undoubtedly that called the pyloric valve, which is often nothing more than a mere 
 elevation of the membrane by the sphincter muscle.* This cellular fold is equally op- 
 posed to the regurgitation of food from the duodenum into the stomach, and to its 
 passage from the stomach into the duodenum ; it is completely effaced by distension, 
 and it belongs as much to the duodenum as to the stomach. Its upper half has the 
 characters of the gastric ; the lower half offers those of the duodenal mucous membrane. 
 Diseases are sometimes observed to stop at the line of separation. We may add, that 
 the folds upon the internal surface of the stomach are formed by the mucous membrane 
 alone ; the fibrous coat does not enter into them. 
 
 Besides these folds, the mucous membrane presents numerous slight and tortuous 
 furrows, dividing it into small spaces or compartments, which are either lozenge-shaped, 
 hexagonal, polygonal, circular, oblong, or irregular. 
 
 Examined by the naked eye, the mucous membrane has a soft, spongy, tomentose, or 
 velvety appearance ; hence the name of villous or velvet-like membrane, by which it is still 
 generally known. It is covered by a layer of mucus of variable thickness, which may 
 be detached by friction with a coarse cloth. In order to avoid the inconveniences arising 
 from this method, which is more or less injurious to the texture of the membrane, I have 
 been accustomed to use a gentle stream of water, which, at the same time that it com- 
 pletely washes away the mucus, clearly displays the papillary structure of the surface 
 of the membrane. 
 
 There are some stomachs which might be called granular or glandjtlar, because the 
 mucous membrane has a granular appearance, so that at first sight it might be imagined 
 that some small glandular bodies (like the salivary glands) were scattered over the in- 
 ternal surface of the stomach ; but this glandular aspect is merely apparent, depending 
 upon the circular or semicircular direction of the furrows in the mucous membrane, 
 which give a spheroidal character to the kind of islets that are intercepted between them. 
 This gi'anular appearance is seldom observed over the entire stomach ; it rarely exists 
 at the great extremity. I have found it limited to the great curvature ; most frequently 
 it occurs in the vicinity of the pylorus ; sometimes it is observed over all that part of the 
 stomach which is to the right of the oesophagus. These granulations are particularly 
 developed in the stomach of the pig. 
 
 There is one remark upon which too much importance cannot be placed ; and that is, 
 the difference in the appearance of the mucous membrane of the great extremity of the 
 stomach, and of the part situated to the right of the oesophagus. Sometimes the line of 
 separation forms a perfect circle ; and this is a very remarkable fact, because in man, 
 who has a single stomach, it may be considered as a rudiment of the division into the 
 compound stomachs found in the lower animals ; for a multiple stomach results rather 
 from some difference in the structure of the mucous membrane, than from the existence 
 of different compartments or distinct cavities. It will not be uninteresting to connect 
 this remark with what has been already stated regarding bilocular stomachs. 
 
 We shall now examine the characters of the mucous membrane in the oesophageal and 
 in the pyloric portion of the stomach. 
 
 In the oesophageal portion it is thinner, softer, and more vascular, and can only be 
 separated in flakes from the subjacent parts. When the stomach contains any liquid 
 after death, this part is converted into a sort of pulp, which becomes of a blackish colour, 
 from the action of the acids in the gastric fluid upon the blood contained in the vessels 
 of the stomach. This is the pultaceous softening, which I regard as a post-mortem change, 
 
 * [It usually consists of the mucous membraue, the cellular coat, and the circular muscular fibres.] 
 
THE STOMACH. 359 
 
 but which has been erroneously confounded with the gelatiniform softening. I'his second 
 portion of the mucous membrane, i. e., the part situated to the right of the oesophagus, 
 is thicker, stronger, and whiter, and may be separated entire from the other coats. Dis- 
 eases often observe the line of separation between the right and the left portions of the 
 stomach. 
 
 Modern pathologists having attached great importance to the condition of the gastric 
 mucous membrane, it has become highly interesting to determine its characters in the 
 healthy state ; these characters relate to its colour, its consistence, and its thickness. 
 
 Colour. — It is extremely difficult to determine what is the natural colour of this mucous 
 membrane. The opinion generally maintained by the best authorities, that it is either 
 primarily or secondarily affected in the majority of diseases, compels us to reject all ob- 
 servations made upon persons who have died from acute or chronic diseases, or even 
 from wounds or injuries of long standing. We are, therefore, obliged to have recourse 
 to cases of accidental death in persons previously in health. In such cases, for example, 
 in criminals who are executed while the stomach is empty, the mucous membrane is 
 found of a grayish-white colour, with a slight tint of yellow and pink.* When death has 
 occurred during digestion, the mucous membrane is found to vary from a delicate pink 
 to the most vivid red. After putrefaction has made some little progress, we find a red 
 or port wine colour, or a brownish black tint prevailing over the great extremity of the 
 stomach, and at the free edges of the folds or wrinkles to which the vessels correspond ; 
 again, it is often found marked with blackish patches, or marbled ; but these discolora- 
 tions are the result of post-mortem transudation. 
 
 In the pultaceous and blackish softening of the mucous membrane, the colour is owing 
 to the action of the acids in the gastric juice. Wlien the stomach contains bile, the mu- 
 cous membrane is tinged with yellow or green, and the stain sometimes remains after 
 the longest maceration. 
 
 If the mucous membrane be rubbed with a rough cloth, so long as the vessels contain 
 blood, we may produce a red punctuated appearance, which has been often mistaken for 
 a sign of inflammation. Lastly, in the aged we not unfrequently observe a slate gray 
 colour, either in points or in patches, or diffused over the surface. This colour occupies 
 the papillae, and may afford proof of some former irritation, but is certainly not due to any 
 diseased action during the later periods of life. These different discolorations of the 
 stomach must not be confounded with the alterations in its colour resulting from disease. 
 
 Thickness. — It is difficult to estimate the exact thickness of the gastric mucous mem- 
 brane. Like the muscular coat, it varies in different individuals ; in chronic inflamma- 
 tion it is twice or three times its natural thickness. In determining the thickness of this 
 membrane, it is important to bear in mind the difference in this particular between the 
 oesophageal and pyloric portions ; the former being extremely thin, and the latter twice 
 or three times as thick as that. 
 
 Consistence. — The same remarks apply to its consistence, for there are many individ- 
 ual varieties in this respect. The oesophageal portion may be torn with great ease ; but 
 the pyloric portion is so dense, that the back, and even the edge of a scalpel, may be 
 drawn over it with considerable force without wounding it. If there has been any liquid, 
 or even food in the stomach, in however small quantity, the mucous membrane of the 
 oesophageal portion, when macerated, is converted into a pulp ; moderate distension will 
 then rupture the weills of the stomach, which may be broken through by the point of the 
 finger. 
 
 From want of sufficient reflection upon this subject, men of great merit have commit- 
 ted serious errors in the appreciation of morbid lesions. In the gelatiniform softening, 
 the gastric mucous membrane, as well as the other coats of the stomach, become dis- 
 solved, and resemble a solution of gelatine. In many old people, and in some adults, I 
 have found the mucous membrane so thick and so strong, that it could be dissected off 
 entire, and removed in one piece. This condition coexisted with the slate colour, either 
 accompanied or not with chronic inflammation. 
 
 The PapillcB. — If we examine the mucous membrane of the stomach, placed under wa- 
 ter, and exposed to the direct rays of the sun by the aid of a powerful lens, we shall find 
 that its surface is very irregular, mammillated. Fig. 152. Fig. 153. 
 and furrowed, so as to present an appearance very 
 like the convolutions of the small intestine. The 
 eminences, which are much more distinct to- 
 wards the pylorus than near the oesophagus, are 
 studded with holes, or, rather, with small pits 
 resembling the cells of a honeycomb (figs. 152, 
 153). These alveolar depressions are well de- 
 scribed by Home, who states that they exist only r-i m -tj^an— « 
 
 in the great cul-de-sac, while the viUi occupy the ""'il^fi J32 a.aB.rt^!' ^^S^S^toT 
 
 * In a great number of individuals who have died from acute or chronic diseases, the gastric mucous mem- 
 brane is found in the same state as in those who have died accidentally ; it is, therefore, not always affectedi 
 either primarily or secondarily, in disease 
 
360 SPLANCHNOLOGY. 
 
 rest of the stomach. The truth is, that a precisely similar stmcture is observed ovei 
 the whole stomach. The alveoli, or pits, are separated from each other by small pro- 
 jections, or papilla {fig. 153), of vi^hich the papillae of the tongue convey an excellent idea.* 
 
 Should these papillae be distinguished from other projections that have been termed 
 villi, by Ruysch, for example, who called the entire membrane villoso-papillaris ? Aftei 
 the most minute examination, I have only detected one order of eminences,! viz., the 
 papilla, the existence of which I regard as the essential character of all tegumentary 
 membranes, whether mucous or cutaneous, which might all, therefore, be designated 
 papillary membranes. We shall return again to the structure of the papillse. 
 
 If we examine with a lens or simple microscope a perpendicular or oblique section 
 of the mucous membrane of the stomach, we shall perceive that it consists essentially of 
 a strong membrane, the mucous dermis, from which arise an immense number of small 
 eminences closely pressed together, and of unequal lengths, like the pile of velvet. 
 These eminences are the papillae ; they are liable to great enlargement in cases of hy- 
 pertrophy, and then the structure just described becomes very apparent. 
 
 The Follicles. — The follicles of the stomach can be very easily demonstrated in the 
 pigt and in the horse. In the last-mentioned animal, entozoa are frequently found in 
 the centre of these follicles, which then become developed into hard, and sometimes 
 very large tumours. It is so difficult to demonstrate them in the human subject, that, 
 with most anatomists, I, for a long time, doubted their existence. Haller only saw them 
 once or twice ;^ but in some individuals they are very distinct. I found them well 
 marked in a great number of cholera patients. II They are not situated in the sub-mucous 
 cellular tissue, as is generally stated, but in the substance of the membrane itself, so as 
 to form a projection on the inside of the stomach, but not on the outer surface. They 
 are rounded, flattened, and perforated by a central foramen, which is usually visible to 
 the naked eye. I have observed them upon all points of the mucous membrane, but they 
 appear to be most numerous near the oesophageal orifice, and along the lesser curvature. IT 
 
 The Vessels and Nerves of the Stomach. — The arteries are very large and numerous in 
 proportion to the size of the stomach ; they must, therefore, assist in the performance 
 of some function besides the mere nutrition of the organ ; this function is the secretion 
 of the gastric juice. They all arise from the cceliac axis, and are the coronary, the su- 
 perior pyloric and right gastro-epiploic branches of the hepatic, and the left gastro-epi- 
 ploic and vasa brevia, which are branches of the splenic artery. These arteries anas- 
 tomose, so as to form around the stomach a vascular zone, which is in close contact 
 with that organ during distension, but at some distance from it when empty. From this 
 arterial circle branches are given off, which at first lie between the peritoneal and the 
 muscular coats, but, after a certain number of divisions and anastomoses, perforate the 
 muscular and fibrous coats, and again subdivide and anastomose a great number of times 
 in the loose sub-mucous cellular tissue, until, having become capillary, they penetrate the 
 mucous membrane. 
 
 The veins bear the same name, and follow the same direction as the arteries ; they 
 contribute to form the vena portae. Schmiedel (Variet. Vasorum, No. xix., p. 26) has 
 seen the coronary vein of the stomach anastomose with the renal vein, the pyloric with 
 the vena azygos, and one of the venae breves with the phrenic vein. 
 
 The lymphatic vessels are very numerous, and terminate in the lymphatic glands, situ- 
 ated along the two curvatures of the stomach. The peculiar ducts, said to proceed from 
 the spleen to the stomach, and supposed by the ancients to be passages for the atra bilis, 
 are purely imaginary. 
 
 The nerves are of two kinds, some being derived from the eighth pair, and others from 
 the solar plexus. 
 
 The nerves of the eighth pair form a plexus around the cardiac orifice, the left nerve 
 being distributed upon the anterior, and the right upon the posterior surface of the stom- 
 
 * [The alveoli are from t^tt'^ '■° oTo*^ °^ ^^ inch, and, near the pylorus, y^n^th of an inch in diameter. 
 At the bottom of each alveolus is seen a group of minute apertures (fig. 152), which are the open mouths of 
 small tubes placed perpendicularly to the surface of the membrane, and closed at the other end. In a vertical 
 section of the membrane, these tubes, which average about -jijyth of an inch in diameter, are seen to rest upon 
 the sub-mucous tissue by their closed extremities. In the cardiac portion of the stomach they are short and 
 stiuight ; near the pyloric end they are longer, and convoluted, or irregularly dilated, and are sometimes bifur- 
 cated. Bloodvessels pass up between these tubes, and form a capillary network round the borders of the al- 
 veoli. The membranous projections sometimes found between the alveoli {fig. 153) form irregular fringes, 
 broader than the lingual papillae, and seem rather to be imperfectly developed villi (see note, p. 361), and are 
 usually so called. The epithelium covering the entire mucous membrane of the stomach consists of a single 
 layer of minute columnar cells ; it is very delicate, and invisible, except by a high magnifying power ; hence 
 its existence was formerly denied.] 
 
 t Upon this subject see the Memoir of Helvetius.— (/Tj'ii. Acad. Roy. des Sciences, 1720.) 
 
 t [In the pig these follicles appear to be nothing more than prolongations of the mucous membrane, or 
 small diverticula; so that, after having detached the mucous membrane, they may, by slight pressure, be 
 turned inside out.] 
 
 t> " Neque rejici debent, etsi non semper possint ostendi." — (Haller, 1. vi., lib. xix., p. 140.) 
 
 II Vide Anat. Path, avec planches, liv. xiv., pi. 1. 
 
 IT [In the neighbourhood of the (esophageal orifice there are also several small cgmpound glands, analogous 
 to Brunner's glands in the duodenum. — (W. S.)] 
 
THE INTESTINES. 36] 
 
 ach. They may be followed as far as the muscular coat, where they seem to be lost , 
 division of them paralyzes this coat. By means of the nerves of the eighth pair, the 
 stomach is connected with the oesophagus, the lungs, the pharynx, the larynx, and' the 
 heart. Through the nerves derived from the central epigastric plexus, and named after 
 the arteries that support them, the stomach is connected with the ganglionic system 
 and is brought into relation with the numerous viscera of the abdomen. 
 
 Lastly, a very delicate serous cellular tissue unites the different coats of the stomach. 
 There are three layers of this tissue, viz., one between the peritoneal and the muscular 
 coats, another between the muscular and the fibrous, and a third between the fibrous 
 and the mucous coats. The last of these is the most distinct ; it is liable to both serous 
 and sanguineous effusions, and may become the seat of diffuse inflammation. I have 
 lately seen it infiltrated with pus to a considerable extent, the mucous and the fibrous 
 coats being both perfectly healthy. 
 
 Develcypment of the Stomach. — The stomach of the foetus is remarkable on account of 
 its vertical position, which is due to the great development of the liver, especially of its 
 left lobe. An unnatural development of that lobe will also occasion a similar position 
 of the stomach in the adult. The relative smallness of the stomach, and the slight de- 
 velopment of its tuberosity, are also characteristic of its foetal condition.* Nevertheless, 
 from the first moment of its appearance, it is distinguished from the rest of the aliment- 
 ary canal by its greater size. The changes which the adult stomach undergoes, and 
 the variations in size which it presents, are, perhaps, less dependant upon congenital 
 differences than upon particular habits. The differences in the two sexes are manifest- 
 ly due to the pressure to which the stomach of the female is subject, either from the use 
 of stays or from the gravid uterus. I may here advert to the development of the mus- 
 cular ring of the pylorus, and of the neighbouring part of the stomach in aged persons. 
 
 Function. — The stomach is the organ of chymification, or of that process by which the 
 food is converted into a homogeneous gray pulp, called chyme. For that purpose it is 
 evidently necessary that the food should remain for some time in this organ, and the 
 elasticity of the muscular coat of the oesophagus and of the ring at the pylorus are suffi- 
 cient to prevent its regurgitation into the gullet, or its passage into the duodenum. 
 When the process is completed, however, the peristaltic contraction of the muscular 
 fibres of the stomach overcomes the resistance of the pylorus ; in eructation, regurgita- 
 tion, and vomiting, the same peristaltic movements are assisted by the contraction of 
 the diaphragm and the abdominal muscles. 
 
 Chymification is a chemical, or, at least, a molecular action, and is effected by means 
 of the gastric juice, mixed with the salivary and oesophageal secretions. These fluids 
 are acid.t 
 
 The influence of the nerves upon digestion has been ascertained by ingenious experi- 
 ments, the results of which, however, have been interpreted in various ways. 
 
 The Intestines in general. 
 The term intestine, in its widest signification, is applied to the whole alimentary ca- 
 nal ; but, in a more limited sense, it means that long and frequently-convoluted tube, 
 extending from the pylorus to the anus, and occupying almost the whole of the abdomi- 
 nal cavity. The intestines have been divided, according to their calibre, into the small 
 {b to d,Jig. 139) and the large (c to i) ; this distinction, which is applicable to most ani- 
 mals, is anatomically established in man by a difference in size, by the sacculated char- 
 acter of the large intestine, by a difference in direction, by the presence of a valve, by 
 the existence of a caecum and of a vermiform appendix, and, lastly, by a difference in 
 structure, especially in the muscular and mucous coats. Tlie same distinction is recog 
 nised in physiology, and upon equally good grounds, for the small intestine is essentid- 
 ly concerned in the formation and absorption of the chyle, while the large intestine is the 
 organ of defsecation.J These differences will be rendered more apparent from the de 
 scription of these two important parts of the alimentary canal. 
 
 The Small Intestine. 
 The small intestine includes all that part which is situated between the stomach and 
 the large intestine (i to d,fig. 139). According to Haller, Bichat, and their followers, 
 the upper portion, called the duodenum (b to c), should be abstracted from the small in- 
 testine, which, according to them, would commence at the termination of the duodenum. 
 It appears to me that the former definition should be adhered to, on account both of the 
 
 * [At early periods of foetal life, villi are found on the mucous membrane of the stomach g-enerally, after- 
 ward on the pyloric portion only ; and, subsequently to birth, the only traces of these are the irregular frmgcB 
 observed here and there between the alveoli.] 
 
 t [The saliva, though sometimes acid, is usually alkaline.] 
 
 i The division into a small and large intestine exists among all vertebrated animals ; but no animals, ex- 
 cepting the ourangs and the wombat, have both a ciecum and an appendix vermiformis. In some we find one 
 caecum, or several caeca ; in others, one or more vermiform appendices ; others have neither csecum nor appen- 
 dix, but a valvular fola arit a well-marked change in diameter indicate the limit between the small ana larf« 
 intestines. In some, again, the only difference consists in a change of diameter. 
 
 Zz 
 
9m 
 
 SPLANCHNOLOGY. 
 
 absence of any real line of separation between the duodenum and the rest of the small 
 intestine, and of their similarity in structure and function. 
 
 The small intestine is divided into three parts, the duodenum, the jejunum, and the 
 ileum. The division between the duodenum and the rest of the small intestine is defi- 
 nite, but that between the jejunum and the ileum is altogether arbitrary ; so that we 
 shall follow the example of Haller, Scemmering, and others, in describing the jejunum 
 and ileum together (c to d), under the name of the small intestine, properly so called. 
 
 The Duodenum. 
 Dissection. — ^When the abdomen is opened, the first portion only of this intestine is 
 visible ; the second is hid by the ascending colon ; the third is seen in the cavity of the 
 omentum. The second is brought into view by turning aside the colon. The third por- 
 tion, which is the most difficult to demonstrate, may be exposed in two ways : either by 
 cutting through the inferior layer of the transverse mesocolon, or by turning the stomach 
 upward, after having divided the lavers of the grest omentum, which are attached along 
 its greater curvature. 
 
 Fig- 154. The duodenum {dudsKa 
 
 6uKTvXov, p b, Jig. 154), so 
 called by Herophilus (Ga- 
 len, Administr. Ariat., lib. 
 vi., c. 9) on account of its 
 being about equal in length 
 to the breadth of twelve fin- 
 gers, commences at the py- 
 lorus, and terminates, with- 
 out any precise line of de- 
 marcation, to the left of the 
 second lumbar vertebra, at 
 the point where the small 
 intestine enters into the 
 mesentery, or, rather, op- 
 posite the superior mesen- 
 teric artery (m) and vein, 
 which pass in front of it. 
 Its fixed position, its struc- 
 ture, and its curvatures, 
 have led to its being de- 
 scribed separately.* 
 
 It is difficult to determine its precise situation with regard to the abdominal parietes. 
 It is not exclusively confined to any one region, but occupies in succession the adjacent 
 borders of the right hypochondrium and the epigastrium, of the right lumbar and the um- 
 bilical regions, and of the epigastric and umbilical regions. 
 
 The duodenum is found more deeply situated in proportion as we recede from the py- 
 lorus, and hence the difficulty of exploring it through the parietes of the abdomen. It 
 is fixed firmly in its place by the peritoneum, by the mesenteric vessels and nerves, 
 which bind it down, and by the pancreas. This fixedness is one of its principal peculi- 
 arities, and is indispensable in consequence of its relations with the ductus communis 
 choledochus ; for had it been movable like the rest of the small intestine, incessant ob- 
 structions to the flow of the bile would have occurred. It follows, also, that the duode- 
 num can never form part of a hernia ; its first portion may, indeed, be displaced, for it 
 is less firmly fixed than the remainder, and is sometimes dragged out of its proper situ- 
 ation by the pyloric extremity of the stomach. 
 
 Dimensions. — It is eight or nine inches in length ; its calibre is somewhat greater than 
 that of the rest of the small intestine, but the difference is not so decided as to war- 
 rant the names of second stomach, or ventriculus sUccenturiatus, which have been given to 
 it. I have even met with subjects in whom the duodenum, when moderately distended, 
 was five inches, while the succeeding portion of small intestine was six inches in cir- 
 cumference. It has been supposed that this part is more dilatable than the rest of the 
 small intestine ; this has been attributed to the absence of the peritoneum. The fact 
 and the explanation are equally without foundation. It is the fibrous membrane, and 
 not the peritoneal coat, which is opposed to dilatation of the intestines. 
 
 Direction. — This is very remarkable. Commencing at the pylorus, the duodenum 
 passes upward to the right side and backward ; having reached the neck of the gall- 
 bladder, it suddenly changes its direction, and becomes vertical, forming an acute angle 
 ■with the former portion ; this is its first curvature (e) : then, after proceeding vertically 
 through a variable space, it passes transversely from the right to the left side, and be- 
 comes continuous with the rest of the small intestine. This change in its direction 
 takes place at a right angle, and is, therefore, less abrupt than the former ; the point at 
 which it occurs is called the second curvatare (e'). 
 * Glisson considered the insertion of the ductus communis chnlfidochm! "■••'"' ".-er limit of the duodtJiiuni. 
 
THE INTESTINES. 
 
 363 
 
 It follows, then, that the duodenum describes a double curve, or, rather, one single 
 curve, of which the concavity is directed towards the left, and the convexity to the right 
 side. Haller has ingeniously- compared the course of the duodenum to two parallel 
 lines, intersected by a perpendicular. This double change in the direction of the duode- 
 num, which is probably intended to retard the passage of the food, enables us to consider 
 it as composed of three portions, distinguished as the first (p e), second (e e'), and third (e' d). 
 
 Relations. — These should be studied in each of the three portions. 
 
 Relations of the First Portion. — Above, with the liver (/', fig. 154*) and the gall-bladder 
 (g), to the neck of which it is united by a fold of the peritoneum. It is not uncommon 
 to see the gall-bladder and the duodenum closely adherent to each other, and to find an 
 opening through which biliary calculi have passed into the gut. Li front, with the gas- 
 tro-colic omentum and the abdominal parietes. Behind, with the hepatic vessels, and 
 the gastro-hepatic omentum. This portion of the duodenum, which may be denomi- 
 nated the hepatic, is about two inches in length. 
 
 Relations of the Second Portion. — In front, with the right extremity of the arch of the 
 colon (t,fig. 161, e being the duodenum), which crosses it at a right angle. Behind, with 
 the concave border of the right kidney, along which it descends to a greater or less dis- 
 tance, together with the vena cava inferior and the ductus communis choledochus. Some- 
 times this portion is not in relation with the kidney, but rather with the vertebral col- 
 umn. The ductus communis choledochus {c,fig. 169) and the pancreatic duct (m) enter 
 the intestine at the posterior and inner surface, and below the middle of this portion of 
 the duodenum. The relations of the duodenum behind are direct, i. c., without the in- 
 tervention of the peritoneum. On the right, this portion of the duodenum is in relation 
 with the ascending colon {a, fig. 161). On the left, with the pancreas {o,fig. 154), which 
 is closely united to it, and embraces it in a sort of half groove. This second portion is 
 two or three inches in length ; it may be called the renal portion. 
 
 Relations of the Third Portion. — The third portion is situated in the substance of the 
 adherent border of the transverse mesocolon. Below, it rests upon the lower border of 
 that fold. Above, it is bounded by the pancreas, which adheres closely to it. In front, 
 it corresponds to the stomach, from which it is separated by the layer of peritoneum 
 which lines the sac of the great omentum. Behind, it corresponds to the vertebral col- 
 lunn, from which it is separated by the aorta (a), the vena cava, and the pillars of the 
 diaphragm {d d).i 
 
 As the internal surface and the structure of the duodenum are very analogous to those 
 of the jejunum and ileum, I shall postpone the description until I have noticed the exter- 
 nal conformation of the rest of the small intestine. 
 
 Fig. 155. 
 The Small Intestine, or the Jejunnm and 
 
 Ileum. 
 The small intestine, properly so call- 
 ed (c d,fig. 139 ; i i i,fig. 155), or the 
 jejunum and ileum, consists of that por- 
 tion of the alimentary canal which fills 
 almost the whole of the abdomen, oc- 
 cupies the mnbilical, hypogastric, iliac, 
 and lumbar regions, and is surround- 
 ed, as it were, more or less complete- 
 ly, by the large intestine {efgh, fig. 
 139 ; a t d, fig. 155). Its upper ex- 
 tremity (/ fig. 161) is continuous, 
 without any hne of separation, with 
 the duodenum. The distinction be- 
 tween the two parts is established by 
 the angle which the mesentery forms 
 with the mesocolon, or, rather, by the 
 point where the superior mesenteric 
 vessels cross over the small intestine. 
 Its lower extremity {d,fig. 139 ; i,fig. 
 161) enters at a right angle into the 
 large intestine. The old division of 
 the small intestine into the jejunum 
 and ileum should be banished with oth- 
 er anatomical niceties, for it is found- 
 ed only upon trivial distinctions ; and 
 although the upper part of this intes- 
 tine differs in many respects from the 
 
 * In which figure the liver and stomach are turned upward. 
 
 t In one subject I found a fourth portion which passed upward, and was ahmit one inch ir len!?th, so that 
 the duodenum described a third curve, with its conc.avitv directed to the right. 
 
364 SPLANCHNOLOGY. 
 
 lower, still the alteration takes place by imperceptible gradations.* So that Winslow, 
 unable to find any real difference, established a purely conventional distinction, by pro- 
 posing to call the upper two fifths the jejunum, and the lower three fifths the ileum. 
 
 No portion of the alimentary canal is so movable as the small intestine, properly so 
 called. It is exceedingly loosely attached, or, as it were, suspended from the vertebral 
 column, by a large fold of the peritoneum, called the mesentery (the attached portion of 
 which is seen at m,fig. 161), which, being broader in the middle than at either extrem- 
 ity, gives an unequal mobility to the different parts supported by it. The small intes- 
 tine is displaced with great facility. 
 
 The circular boundary described around it by the large intestine is only exact above, 
 where the mesocolon and the arch of the colon («, fig. 155) completely separate it from the 
 stomach («), the liver (Z), the spleen (k), and the duodenum. But below, between the 
 caecum {c,fig- 161) and the sigmoid flexure of the colon (/), it descends into the pelvis, 
 and, extending laterally, passes in front of the colon in both the right and left lumbar re- 
 gions. 
 
 This excessive mobility is one of the most characteristic and important facts regarding 
 the small intestine, which, in some measure, floats in the abdominal cavity, yielding to 
 the slightest impulse or concussion. Of all the viscera, it is the most frequently involv- 
 ed in hernia. It is liable to invagination, i. e., one portion may be received, as into a 
 sheath, into that immediately succeeding it. When any organ in the abdomen becomes 
 enlarged, the small intestine yields, and passes in the direction where there is least re- 
 sistance. It appears to partake of the mobility of fluids. It collects together, or spreads 
 out ; it moulds itself upon the adjacent parts, and fills up every space, so as to elude aU 
 causes of compression ; and, by means of this admirable contrivance, the abdomen ac- 
 commodates itself without inconvenience to the occasional enormous development, either 
 natural or diseased, of the organs contained within it. 
 
 Direction. — We have seen that the upper or supra-diaphragmatic portion of the diges- 
 tive canal is straight. The stomach presents one slight curve. The duodenum has two 
 decided curves, and the rest of the small intestine pursues a not less flexuous course. 
 The following is the direction of this intestine: commencing at the duodenum {j,fig- 
 161), it passes forward and to the left side ; it is then folded a great number of times 
 upon itself, and, at its lower part, it passes transversely from the left to the right side, 
 and a little upward, in order to enter at a right angle (i) into the great intestine. 
 
 The numerous foldings or turnings (gyri) of the small intestine upon itself have re- 
 ceived the name of convolutions ; they are moulded upon each other, without intermixing 
 or becoming entangled, so as to form a mass, which so closely resembles the surface of 
 the brain, that the term convolutions has also been applied to the winding eminences of 
 that organ. 
 
 Each convolution represents an almost complete circle. In the complexity presented 
 by the numerous windings of the small intestine, it appears to be very difficult to assign 
 to it any general direction ; nevertheless, if we consider that the small intestine com- 
 mences to the left of the second lumbar vertebra, and terminates in the right iliac fossa, 
 it will be seen that its general direction coincides with that of the membranous fold (m, 
 Jig. 161) which supports it ; that is, it may be expressed by an oblique line ruiming 
 downward from the left to the right side. If, however, we examine the particular di- 
 rection of the convolutions, we shall find that they all present a concavity towards the 
 mesentery, and a convexity towards the parietes of the abdomen, so that each resem- 
 bles the half of the figure 8. In consequence of this arrangement, the intestine may be- 
 come folded without much change in its position, either in advance or otherwise ; and 
 hence the great number of folds which can be placed between two points so near each 
 other as the left side of the second lumbar vertebra and the right iliac fossa, the distance 
 between which is not more than four inches. 
 
 Dimensions. — The determination of the length of the small intestine, properly so called, 
 has at all times been a subject of interest. Meckel says that it varies from thirteen to 
 twenty-seven feet, including the duodenum. According to my observations, it varies 
 from ten to twenty-five feet in the adult, t The length of the small intestine, compared 
 to that of the large intestine, is generally as five to one. The different results which 
 have been obtained by various authors may be explained partly by individual varieties 
 and partly by the mode in which the measurements were made. Thus, a more or less 
 perfect separation of the gut from the membranous folds which support it would lead to 
 different results. But another, and less understood cause of difference, is the influence 
 of the caliber of the intestine upon its length. The caliber and the length have always 
 an inverse ratio to each other. Of this we may be easily convinced, by strongly infla- 
 ting a portion of gut which has been previously measured. I have often been struck 
 
 * The upper part of the intestine is caWed jejunum, because it is generally found empty ; the second, ileum, 
 either because it has been supposed chiefly to occupy the iliac regions, or on account of its convoluted disposi- 
 tion, which, however, is common to it with the other (tiXtti', to turn, to twist). 
 
 t The average length of the small intestine, including the duodenum, is 20 feet. I have lately measured 
 several : in a female affected with chronic peritonitis, it was only 7 feet long ; in another, 14 ; in a third, 18 ; 
 in a fourth, 20 ; and in a fifth, 22. 
 
THE INTESTINES. 365 
 
 with the shortness of the small intestine in cases of hernia, accompanied with retention 
 of the contents of the gut above the strangulation. 
 
 Some authors have attempted to establish a relation between the length of the intes- 
 tine and the stature of the individual ; and it has been affirmed that the former is four 
 or five times the height of the body. But differences in stature have not a uniform rela- 
 tion to the length of the alimentary canal. 
 
 Lastly, individual varieties in the length of the small intestine do not appear to h8T6 
 any influence upon the activity of the digestive process. 
 
 Caliber. — The cahber of the small intestine, properly so called, is not the same through- 
 out. It is greater at the commencement than at the termination of the intestine. When 
 moderately distended by inflation, I have found it six inches and four hnes in circum- 
 ference at its commencement, four inches and two lines at the middle, and three inches 
 and a half a little above its entrance into the large intestine ; but at the point of entrance 
 itself it is dilated to about four inches and a half 
 
 The small intestine, therefore, is funnel-shaped, a form which must facilitate the rapid 
 passage of its contents, by causing them to proceed from a wider into a narrower space. 
 
 Lastly, the caliber of the small intestine presents many varieties. When any obstruc- 
 tion occurs to the passage of its contents, it may attain the caliber of the large intestine. 
 In certain cases of marasmus, when it contains no gases, it becomes so contracted that 
 the tube is completely obliterated. 
 
 Figure and Relations. — The smaU intestine is cylindrical ; a section of it is almost cir- 
 cular. Its posterior harder, to which the mesentery is attached, is concave ; it is thrown 
 into shght folds, as every straight cylinder must be when it is bent into a curve. Its 
 anterior border is convex, free, and corresponds to the abdominal parietes, being separa- 
 ted from them by the great omentum,* which seems intended to contain the whole mass 
 of the intestinal convolutions. When the omentum is wanting, as in the foetus, or in 
 cases of displacement from its being rolled up into a cord, the small intestine is in im- 
 mediate contact with the parietes of the abdomen. 
 
 The lateral surfaces of the different convolutions of the small intestine are in contact 
 with each other. As these surfaces are convex, they intercept triangular spaces before 
 and after them, in which either effused blood, or serum, or pus, or false membranes, are 
 sometimes collected. 
 
 The small intestine corresponds to all the regions of the abdomen, excepting those of 
 the upper zone. Not uncommonly, we find it escaped from under the omentum, and sit- 
 uated between the hver and the abdominal parietes, or reaching into the left hypochon- 
 drium. It is immediately forced, as it were, in any direction in which there may be an 
 opening, t 
 
 More or less of the small intestine is always found in the pelvis ; in the male, between 
 the bladder and the rectum ; in the female, between the bladder and the uterus, and be- 
 tween the uterus and the rectum. In several persons who were emaciated from chronic 
 diseases, and in whom the vertebral column could be plainly felt through the parietes of 
 the abdomen, I have found almost the whole, and, in some cases, even the whole, of the 
 small intestine within the pelvis, contracted, and almost entirely void of air. When one 
 portion only of the small intestine is in the pelvis, it is invariably the lower part. 
 
 WTien any large mass is developed in the abdomen, as in pregnancy, or in encysted 
 dropsy of the ovarium, the small intestine passes upward and laterally, becomes diffu- 
 sed, fills up every space, and almost always escapes compression in the most remarka- 
 ble manner. 
 
 It is not uncommon to find, in the small intestine, appendices or diverticula, like the 
 fingers of a glove, which are sometimes two or three inches in length, and have been 
 found in the sacs of herniae. These diverticula are usually much nearer the lower than 
 the upper part of the small intestine. They are formed by all the coats of the bowel, 
 and are very different from mere protrusion of the mucous membrane through the mus- 
 cular coat, of which I have seen one example in the duodenum, and which I have often 
 met with in other parts of the small intestine. In a subject which I recently examined, 
 the small intestine presented about fifty spheroidal tumours of unequal size, all situated 
 along the mesenteric side of the gut, and formed by protrusions of the mucous membrane 
 through the muscular fibres. 
 
 Structure of the Small Iritesttne. 
 Dissection. — This structure must be studied upon a distended and moist portion of in- 
 testine, upon a distended and dried specimen, and also upon one inverted and distended. 
 It is also of importance to study the mucous membrane under water, with the assistance 
 of a strong lens. Injections thrown in first by the veins, and then by the arteries, are 
 also useful in developing its structure. t 
 
 * [Injig. 155, the great omentum has been removed.] . . 
 
 t The small intestine is found in diaphragmatic hernicc ; it constitutes perineal hernia ; and it is this por 
 ion of the bowels which escapes from the pelvis when the lower wall of that cavity is divided. 
 t The internal surface of the small intestine will be noticed with the mucous membrane. 
 
 1 
 
 i 
 
366 SPLANCHNOLOGY. 
 
 The small intestine, as well as the stomach, is formed of four coats or membranes, 
 which, proceeding from without inward, are the serous, muscular, fibrous, and mucous coats. 
 
 The Serous Coat. — The arrangement of this coat upon the duodenum differs from that 
 upon the rest of the small intestine. 
 
 The peritoneum is apphed to the first portion of the duodenum in the same way as 
 upon the stomach, i. e., it covers it entirely, excepting in front and behind, where there 
 is a triangular space devoid of this coat. Like the stomach, this first portion gives at- 
 tachment to the great omentum in front, and to the small omentum behind. The fold 
 of peritoneum which passes from the liver to the duodenum has been improperly called 
 the hepatic ligament of the duodenum. The peritoneum merely passes over the front of 
 the second and third portions of the duodenum, so that the posterior surface of the in- 
 testine is in immediate contact with the parts with which it is in relation, and is very 
 perfectly fixed. 
 
 The peritoneum forms a complete sheath for the small intestine, properly so called, ex- 
 cepting along its concave border, where the two layers which constitute the mesentery 
 separate from each other, so as to include the bowel. In this situation we find a trian- 
 gular cellular space, exactly resembling those which we have already described along the 
 curvatures of the stomach, and performing a similar office, viz., that of remedying the 
 slight extensibility of the peritoneum, and permitting the intestine to undergo sudden 
 dilatation to a great extent. We should have a very incorrect notion of the dilatability 
 of the intestine if we imagined that it is limited by the triangular space along its con 
 cavity, for when the bowel is much distended, the mesentery itself becomes separatee 
 into its two layers to allow of such distension. Of this I am convinced from having 
 measured the antero-posterior diameter of the mesentery both before and after inflation 
 of the bowels. 
 
 The cellular tissue which unites the peritoneal to the muscular coat is extremely del- 
 icate, and its adhesion to the latter coat increases in proceeding from the concave to the 
 convex border of the intestine. Although the peritoneal coat is very thin, and so trans- 
 parent that the muscular fibres may be seen through it, yet it has considerable strength. 
 
 The muscular coat is composed of two layers of involuntary muscular fibres, one su- 
 perficial, the other deep. The superficial layer is the thinner ; it consists of longitudinal 
 fibres placed around the bowel in a very regular manner, and forming a continuous plane. 
 I have never found these fibres more numerous at the mesenteric than at the convex 
 border. This layer of fibres is almost always removed with the peritoneal coat, to which 
 it adheres very intimately. From their white colour and shining appearance under the 
 serous membrane, they have been supposed to be of a tendinous nature. 
 
 It is difficult, though by no means important, to determine exactly whether the same 
 fibres reach the whole length of the intestine, or whether they are interrupted at inter- 
 vals. It is generally admitted that they are interrupted, and that their extremities are 
 received in the spaces between other fibres. 
 
 The deep layer of muscular fibres is thicker than the preceding, and consists of circu- 
 lar fibres, either parallel or crossing each other at very acute angles. They appear to 
 me to describe complete circles, and to have their ends united. They have no tendinous 
 intersections. 
 
 The fibrous coat is intermediate between the muscular and mucous tunics, and presents 
 the same characters as in the stomach. 
 
 The Mucous or Papillary Membrane. — Its external surface adheres to the fibrous membrane 
 by a loose cellular tissue, which is liable to serous, sanguineous, and purulent infiltra- 
 tion. The emphysematous or cedematous condition may be imitated in the dead body, 
 by everting a portion of bowel and distending it either with air or water. The tenuity 
 of the mucous membrane displayed in these experiments has led to the opinion that this 
 coat is nothing more than an epithelium, a continuation of the epidermis of the skin, and 
 that the fibrous coat represents the cutaneous dermis. Its internal surface is free, and 
 is covered with more or less mucus ; it is remarkable for its duphcatures or valves, call- 
 ed valvules conniventes ; for its highly-developed papillee, and for the arrangement of its 
 follicles. 
 
 The ValvulcB Conniventes {Valvulce Intestinales). 
 
 Dissection. — Evert the small intestine, so that its external surface becomes internal, and 
 then plunge it in water ; or, what is better, lay open the bowel, and examine its internal 
 surface under water. Also study a portion of intestine inflated and dried. 
 
 Hitherto the mucous membrane of the alimentary canal has only presented to our no 
 tice certain folds which are intended to facilitate the dilatation of that canal, as in the 
 cesophagus and stomach, and which are completely effaced by distension. The folds of 
 the mucous membrane of the small intestine fulfil another purpose ; and although they 
 must, undoubtedly, in some measure assist in the elongation and dilatation of the bowel, 
 yet they are never entirely effaced, however far this extension in length or width maj 
 be carried. These folds deserve a special description. They are called valvulce conni- 
 ventes or the valves of Kerkringius, although Fallopius had given a complete description 
 
THE INTESTINES. 367 
 
 of them before that anatomist. Kerkringius gave them the name of conniventes {con 
 niveo, to close partially). They commence in the duodenmn (see fig. 169), an inch, oi 
 sometimes two inches, from the pylorus ; and it is not unconunon to find them preceded 
 by some vertical folds. They are few and small at first, but become very numerous and 
 very large towards the end of the duodenum and the commencement of the small intestine, 
 properly so called. From the upper two fifths of that intestine they gradually diminish 
 in number, and become less regular and less marked towards the lower part of the small 
 intestine ; sometimes they are altogether wanting in the last two or three feet of the 
 bowel. In some rare cases, I have seen valvulae conniventes as far down as the ileo- 
 caecal valve ; in no part are they sufficiently numerous to have a true imbricated arrange- 
 ment. These valves are placed perpendicularly to the axis of the intestine, and describe 
 one half, two thirds, or three fourths of a circle ; but they seldom form a complete ring. 
 They are broader in the middle, being from two or three lines in width, than at their ex- 
 tremities, which are slender. In order to ascertain their dimensions, they must be 
 placed under water, or studied upon a fresh portion of intestine. They are generally 
 parallel, incline towards each other by their extremities, bifurcate, and send off smdj 
 verticular oblique prolongations. Sometimes we find small valves placed between the 
 larger ones. Some of them are suddenly interrupted, so that they might be supposed, at 
 first sight, to have undergone some loss of substance. Several of them are alternate, 
 and seem to be disposed in a spiral manner ; but there is no general rule in this respect ; 
 their free edge is sometimes directed towards the pylorus, and sometimes towards the 
 ileo-cffical valve. Their direction is very irregular ; they yield to any impulse that may 
 be conamunicated to them, and their free edge passes either upward or downward, ac- 
 cording to circumstances. When examined upon a dried specimen, they resemble very 
 much the diaphragms in optical instruments. 
 
 The valvulae conniventes are formed by folds of mucous membrane, within which we 
 find some loose cellular tissue, different kinds of vessels and nerves. Inflation, by rais- 
 ing the mucous membrane, completely effaces them. The fibrous coat presents a slight 
 thickening opposite the bases of these valves. The valves, notwithstanding the ease 
 with which they are moved, must in some manner retard the passage of the food, with- 
 out offering any decided resistance to it, for that would become a cause of obstruction, 
 and give rise to serious accidents. Their chief use, perhaps, is to increase the extent 
 of surface ; according to Fabricius, they double the surface of the intestine ; Fallopius 
 says they increase it three times, and Kew six times. Soemmering has given the some- 
 what conjectural opinion, that the surface of the intestinal mucous membrane is greater 
 than that of the entire skin (Corpor. Hum. Fabrica, t. vi., p. 295). Although not peculiar 
 to the human species, they are much more developed in man than in the lower animals. 
 
 Besides the valvulag conniventes, the mucous membrane of the small intestine presents 
 some irregular folds, which are effaced by distension. 
 
 The PapilloR, or Villi. 
 
 Preparation. — 1. Place the opened intestine in water, exposing it to a strong light, and 
 agitate the fluid. A stream of water previously received upon the membrane will re- 
 move the mucus, which sometimes forms a tenacious sheath around each papilla.* 2. 
 Roll up a portion of the detached mucous membrane, taking care to turn the adherent 
 surface inward. 3. Evert a loop of intestine, so that the peritoneal coat may be on the 
 inside : stretch it upon a cylinder, and then agitate it in a cylindrical vessel, so as to 
 float out the valves. 
 
 The papilla, or villi, are much more developed in the small intestine than in any other 
 part of the alimentary canal, with the exception of the tongue. Fallopius has the honour 
 of having discovered them. They were T,vell described by Helvetius, Hewson, and Lie- 
 berkuhn, but still more accurately of late by Albert Meckel. When examined by the 
 naked eye and under the microscope, the internal surface of the intestine appears to be 
 roughened by an inunense number of prominences or vilh {figs. 157, 159), resembling 
 very close, short grass, or a very hairy caterpillar. In some animals, as in the dog, and 
 especially in the bear, the villi are so numerous and so long, that they in some degree 
 resemble the filzmientous roots of plants. They are found through the whole length of 
 the small intestine, and cover the valvulae conniventes, as well as the intervals between 
 them. They vary in length : according to Lieberkuhn, they are one fifth of a line ; their 
 maximum length appears to be about four fifths of a line : and I have even found some 
 in the duodenum, which, when extended, were a line in length ; their number is very con- 
 siderable, and attempts havQ been made to determine it. Lieberkuhn computed them at 
 500,000. Several Germans have taken up the subject ; allowing 4000 to every square 
 inch, by a calculation, the exactness of which I have not verified, there would be a mill- 
 ion altogether. I have not observed any well-marked difference as regards the number 
 of the vilh, between the commencement and the termination of the small intestine. It 
 
 * A. Meckel recommends that the mucus should be removed by plunging the intestine first in an arsenical 
 solution, and then in water impregnated with sulphuretted hydrogen ; but the continued action of a stream of 
 water is far preferable. 
 
368 
 
 SPLANCHNOLOGY. 
 
 appears to me that the number and length of the villi are much greater in carnivora than 
 in herbivora. The otter has been said to have the largest vilU of any animal. Their 
 form varies much. In the majority of animals which I have examined, as the dog, cat, 
 calf, and bear, they are fUiform. In the human subject they are all lamellar or foliaceous, 
 but with many varieties. In the duodenum they are curved upon themselves, presenting 
 the appearance of a calyx or corolla, and sometimes adhering to each other by their ex- 
 tremities. In the small intestine, properly so called {figs. 157, 159), they are rectilinear, 
 floating, cylindrical, conical, clubbed at the end, constricted, and sometimes bent in the 
 middle. In the neighbourhood of ulcerations, they are, as it were, cut oiF close or trun- 
 cated, without presenting any alteration in their structure. 
 
 Structure. — Brunner calls them membranous tubes ; Leeuwenhoek regarded them as 
 muscular organs ; Helvetius and Hewson considered them to be small valves, an idea 
 which has been revived and carried out more lately by Albert Meckel. This anatomist, 
 who has given representations of the villi in a great number of animals {Journ. Comple- 
 ment, t. vii., p. 209), regards them as formed of small Icunellae, sometimes twisted upon 
 their axes, like the first leaf of a germinating grain of wheat, and sometimes folded into 
 a semi-canal or groove ; but he considers that all these varieties m^y be referred to that 
 of a lamella, broad at the base and narrow at the apex ; a fundamental form, which may 
 always be demonstrated with the aid of a needle.* 
 
 Lieberkuhn states, that at the base of each villus there is an ampulla, which opens 
 upon the summit of the villus by a single orifice ; and he considers that both the ampul- 
 la and the orifice belong to the commencement of the lacteal vessels ; arteries and veins 
 ramify round the ampuUa ; and each villus has an afferent artery and an efferent vein. 
 According to Mascagni, the villi are composed of an interlacement of bloodvessels and 
 smEill lymphatics, and are covered by an extremely thin membrane, composed of lym- 
 phatics. The following are the results of my own observations : Having had occasion 
 to examine a subject in which the lymphatic vessels were filled with tubercular matter, 
 I was able to trace a lymphatic trunk into each villus (vide Anat. Path, avec planches, 
 liv. 2), which traversed its entire length. This perfectly agrees with Lieberkuhn's ac- 
 count. In another subject I injected mercury into one of the mesenteric veins, and then 
 above the mercury I forced in a coarse black injection. The mercury and a part of the 
 black injection passed into the cavity of the intestine, and a globule of mercury appear- 
 ed upon the summits of the villi, which were blackened from the injection. From this 
 I have concluded that the villi are perforated at their summits. I shall return to this 
 subject again. t 
 
 The Duodenal Glands and Follicles. Preparation. — Some intestines are not well adapt- 
 ed for the study of the follicles, which, indeed, seem to be entirely wanting in them. 
 Others, again, are very favourable for that purpose. The folhcles are rendered more 
 apparent by plunging the intestine into acidulated water. They must be examined from 
 the internal surface of the mucous membrane, and also from its external surface, by re- 
 moving the serous, muscular, and fibrous coats by which they are covered. In the study 
 of the duodenal glands, this last method of investigation is absolutely necessary. 
 
 The follicles are generally divided into two kinds, the simple or solitary, and the ag- 
 minated ; to these we shall add the duodenal glands. 
 
 The Duodenal Glands. — These, properly speaking, are the glands of Brunner. This anat- 
 omist, who had already made some curious experiments upon the pancreas, says that, 
 having partially boiled the duodenum, he observed upon its internal membrane some 
 granular bodies, which he has had figured, resembling the solitary follicles in the neigh- 
 bouring portion of intestine. To this collection of granules he gave the name of the sec- 
 ond pancreas. Farther observations have shown, that in the upper half, or upper two 
 
 * [Many of the villi are certainly cylindrical, and, therefore, not referrible to the fundamental form described 
 by Albert Meckel. In the fostus and young subject they are comparatively broader and flatter, and are con- 
 nected at their bases so as to form folds having irregular margins. In this stage of their development they re- 
 semble the rugiB in the intestines of birds and reptiles.] 
 
 t [The villi contain all the elements of the intestinal mucous membrane ; no nerves, however, have been ao- 
 toally demonstrated in them. 
 
 Fig. 156. 
 
 The bloodvessels are numerous, and form a very 
 Deautiful capillary network in each \';llu8 (3, Jig. 
 156). 
 
 Great differences of opinion have existed, and still 
 exist, as to the mode of origin of the lacteals in the in- 
 testinal villi ; the best authorities, however, agree in 
 stating that they do not commence by open orifices. 
 Rudolphi and A. Meckel considered that they arose by 
 a closed network. Dr. Ilenle found a single dilated 
 but closed lacteal in each viUosity ; and more recent- 
 ly, Krause observed that in each villus the lacteal 
 arose by several branches, some of which ended in 
 free but closed extremities, while others anastomosed 
 together (i,fig. 156). The villi, and, it may be ob- 
 served here, every portion of the intestinal mucous 
 membrane, are covered by a transparent, columnar epithelium, consisting of elongated prismatic nucleated cor- 
 puscules. The perpendicular arrangement of these upon the surface of a villus is shown in the diagram (1, 
 %. 156).] 
 
THE INTESTINES. 
 
 thirds of the duodenum, there is a layer of flattened granular bodies, perfectly distinct 
 from each other, however close they may be. This layer must not be confounded with 
 the glanduliform arrangement of the duodenal villi ; it can only be well seen after hav- 
 ing removed the three outer coats. These granular bodies are nothing more than small 
 (compound) glands, which, when examined with a powerful lens, present all the charac 
 ters of the salivary glands. These glands do not cease abruptly, but become few and 
 scattered towards the lower end of the duodenum ; so that it is by no means inconsist- 
 ent to admit that the solitary folhcles of the rest of the intestinal canal may be of a simi- 
 lar nature.* 
 
 The solitary follicles, or glandula solitaries, are generally known in the present day ao 
 the glands of Brunner {Disput. de Gland Duoden., Heidelberg, 1687, 1715), although that 
 anatomist only described the glands or follicles of the duodenum, which he said dimin- 
 ished in number below that portion of the intestine, and disappeared adtogether in the je- 
 junum. It is, therefore, by an extension of the author's meaning that we speak of the 
 glands of Brunner as occupying the termination of the small intestine, the stomach, and 
 even the large intestine. 
 
 The glandulae solitariae present the appearance of small rounded granulations, like mil- 
 let seeds, projecting upon the internal surface of the mucous membrane, without any 
 distinct orifice, and covered with villi (fig. 157) ; they are found upon the valvulae con- 
 niventes, as well as in the spaces between them. Their number is very considerable ; 
 so that in certain diseases, where they become more prominent than usual, they might 
 be mistaken for a confluent eruption. It is a mistake to say that they diminish in num- 
 ber from the upper towards the lower part of the small intestine, the contrary being 
 nearer to the truth. When examined with the simple microscope, they have appeared 
 to me to be hollow, and filled with mucus. t 
 
 The agminated follicles, or glandular plexuses, are more generally knov^n as the glands 
 of Peyer, although both the solitary and agminated glands were described by that anato- 
 mist. Pechlin noticed them under the name of vesicularum agmina. Willis, Glisson, 
 Malpighi, Duvemey, and Wepfer have given more or less complete descriptions of them: 
 but Peyer (De Glandulis Intestinorum, J. C. Peyer, 1667, 1673), when still a young man, 
 and without any knowledge of the work of Pechlin, described and figured them under 
 the title oi glandula agminatce so accurately as to leave nothing to be desired. 
 
 These agminated glands are arranged in elliptical patches {fig. 158), the long diameter 
 of which corresponds with the direction of the intestine : —g.. 153. 
 
 they are pierced with holes, or small depressions, so that 
 they have a honeycombed appearance ; and hence has 
 arisen the name of plaques gaufries, under which I believe 
 I was the first to describe them : they are all situated on 
 the border opposite to that by which the mesentery is at- 
 tached to the intestine ; that is, along the convex border 
 of the intestine, and never along the concave border, nor 
 even upon either side. They are chiefly found towards the 
 end of the small intestine ; they become more and more 
 scattered as we approach the duodenum, in which, how- 
 ever, Peyer once met with a single patch. Their nuniber 
 varies considerably, twenty, thirty, and even more having 
 been counted. Are they ever entirely wanting 1 The dif- 
 ficulty of detecting them in some subjects has led to their 
 being rejected altogether, or considered as the results of 
 a pathological condition ; but this opinion is clearly at va- 
 riance with observation. Again, these patches are not 
 constant either in situation, form, or dimensions. Some- 
 times they assume the appearance of bands two or three 
 inches in length {fig. 158), and sometimes they form cir- 
 cular or irregular clusters. The largest are found near 
 the ileo-cffical valve. It is not rare to find the termina- 
 tion of the small intestine surrounded by a circular patch ; 
 in other cases, the patches termi- 
 nate some inches above the ileo- 
 ■f!3cal valve, and their place is sup- 
 jjlied by simple follicles. 
 
 * [According to Dr. Boehra (He Gland. Intestm. Struct, penitiori), this is not tte 
 case, the compound glands of Brunner not existing below the commencement of the 
 jejunum.] 
 
 t iFig. 157 is a solitary gland magnified ; it is represented, after Boehm, as a 
 closed vesicle, filled with whitish matter, which contains granules smaller than 
 those of mucus. Villi are seen upon the free surface of its capsule, and it is sur- 
 rounded by the crypts of Lieberkuhn (the mouths of which are indicated by the ^aj^e' 
 spots), which have no communication with the vesicle itself (see also note, p 370J.1 
 A A A 
 
 Fig. 157. 
 
370 SPLANCHNOLOGY. 
 
 These patches are generally contained in the substance of the mucous membrane, to 
 _p. j.g which they give a much greater density, so that, in 
 
 _ ■ ■ these situations, it will bear to be scraped. In some 
 
 f- < ^ ftases they appear to be imbedded in the fibrous coat. 
 
 pi; V,. They should be examined both from the external and 
 
 f' : rwmMfi m internal surfaces of the mucous membrane.* When 
 
 y '.^millll they are filled with their secreted fluid, and are exam- 
 
 ined by transmitted light, they may be compared to the 
 vesicles in the skin of an orange : this observation may 
 be easily made in the day. They evidently consist of 
 collections of glands, exactly resembhng the solitary 
 glands {fig. 159). Each depression appears to be the 
 orifice of one of the follicles, which are quite independ- 
 ent of each other ; so that we sometimes find two or 
 three altered in the middle of a patch, which is other- 
 wise perfectly healthy. Lastly, viUi are found upon the 
 patches of the glandulse agminatae : they occupy the in- 
 tervals between the depressions.! 
 The Follicles or Corjruscules of Lieberkuhn. — Lieberkuhn speaks, also, of innumerable, 
 rounded, whitish foUicles, which are seen between the villi, and of corpuscules which are 
 visible between these follicles. He calculates that there are eighty follicles for eighteen 
 villi, and eight corpuscules for each follicle. I am disposed to think that these follicles 
 and corpuscules, which have never been seen excepting by the microscope, should be refer- 
 red to those globules which are reveededin all the tissues by the aid of a magnifying power. | 
 The Vessels and Nerves. — ^All the arteries of the small intestine, properly so called, are 
 branches of the superior mesenteric. They are very numerous. Those of the duodenum 
 arise from the hepatic. The branches from the superior mesenteric are remarkable for 
 the numerous anastomotic loops which they form before reaching the intestine, for their 
 flexuous course within its coats, and for the series of vascular layers formed by them 
 between the peritoneal and muscular, the muscular and fibrous, and the fibrous and mu- 
 cous coats. The last layer forms a very complicated network, from which the vessels 
 of the mucous membrane are derived. The veins are much larger than the arteries, and 
 present a similar arrangement, except in regard to the flexuous course, which is peculiar 
 to the arteries ; they constitute the superior mesenteric vein, which is one of the prin- 
 cipal branches that contribute to form the vena portae. 
 
 The lymphatic vessels are of two kinds, viz., lacteals and lymphatics, properly so called ; 
 they both enter the numerous lymphatic glands, situated in the mesentery ; those which 
 belong to the duodenum enter the glands above the pancreas. 
 The nerves are derived from the solar plexus. 
 
 The development of the small intestine will be noticed in conjunction with that of the 
 large intestine. 
 
 Uses. — Chylification, i. e., the transformation of the chyme into chyle, is effected in the 
 duodenal portion of the small intestine. The essential agents of this process are the 
 bile and the pancreatic fluid. In the remainder of the small intestine (the jejunum and 
 ileum), the absorption of the chyle takes place. The numerous convolutions, the valvu- 
 lae conniventes, and the villi, all tend to increase the extent of the absorbing surface. 
 The products of exhalation and of follicular secretion serve to complete the digestive 
 process. The contents of the bowels are forced along by the shortening of the longitu- 
 dinal, and the contraction of the circular fibres, the latter producing the vermicular mo- 
 tion of the intestines. 
 
 The Large Intestine. 
 
 The large intestine is that part of the alimentary canal which extends from the end oi 
 the small intestine {d,fig. 139) to the anus (i). It commences in the right iliac region 
 {c,fig. 161), and passes upward (a) as far as the right hypochondrium ; then, having 
 reached the liver, it makes a sharp flexure (the right or hepatic flexure), and proceeds 
 
 * [Their contents are sometimes transparent, and tliey are then very difficult of detection.] 
 
 filn fig. 169, representing part of a patch of Peyer's glands magnified, are seen some of the elevated white 
 bodies described by Boehra as resembling the solitary glands, except in not generally having any villi situated 
 directly upon them. Each is surrounded by a zone of dark points, the elongated openings of the crypts of 
 Lieberkuhn. Many of these crypts are also seen scattered irregularly between the numerous villi ; none of 
 them communicate vpith the interior of the whitish bodies, in which, whether solitary or agminated, Boehm 
 could discover no opening, at least, not in a healthy human intestine. He considers them, therefore, to be closed 
 vesicles, not follicles. 
 
 More recently, however, Krause has observed that, in the pig's intestine, they are occasionally open, independ- 
 ently of disease ; and Dr. Allen Thomson has lately made a similar obsen'ation in reference both to the pig 
 and to the human subject.] 
 
 i [The follicles or crypts of Lieberkuhn are tubes placed more or less perpendicularly to the surface of the 
 mucous membrane, like those in the stomach, but situated more widely apart ; their open mouths are seen 
 scattered over the whole surface of the membrane, or collected around the solitary and agminated glands (figt 
 157, 159). The corpuscules {corpora albicantia), described by the same observer as being situated in the bot- 
 tom of the crypts, are probably collections of desquamated epithelium within them.] 
 
THE INTESTINES. 371 
 
 iransTersely (t) from the right to the left side {transverse arch of the colon) ; in the left 
 h3T)Ochondrium, below the spleen, it again makes a sharp bend and becomes vertical (d), 
 (left or splenic flexure). In the left iliac region (/) it is twice bent upon itself, hke the Ro- 
 man letter S {iliac or sigmoid flexure), and it then dips into the pelvis (r), and terminates 
 at the anus. 
 
 The large intestine, therefore, describes within the abdomen a nearly complete circle, 
 which surrounds the mass of convolutions of the small intestine ; and it occupies the 
 right and left iliac regions, the right and left lumbar, the base of each hypochondriac, 
 and the adjacent borders of the epigastric and umbilical regions. Although it is much 
 more firmly fixed in its place than the small intestine, and is, therefore, less liable to 
 displacement, yet it presents some varieties in length and curvature which have a con- 
 siderable influence over its position. The large intestine is more deeply situated than 
 the small in one part of its extent, but in another is at least quite as superficial. 
 
 From its long course, and from the different relations piesented by its diflferent parts, 
 it has been divided into the ccecum, the colon, which is itself subdivided into several 
 parts, and the rectum. 
 
 Dimensions. — The IcTigth of the large intestine is four or five feet, and, compared with 
 the small intestine, is as one to four ; but it varies considerably, rather, it would seem 
 to me, from the eflfects of repeated distension, than from any original conformation ; for 
 it may be easUy imagined that the bowel cannot be distended transversely without lo- 
 sing somewhat in length, and that, on returning to its former diameter, it must be elon- 
 gated in proportion to the distension it had previously undergone. The large intestine 
 has also generally appeared to me longer in persons advanced in age than in adults. 
 
 Its caliber or diameter usually exceeds that of the small intestine, but may become so 
 reduced that the gut resembles a hard cord, about the size of the little finger. In other 
 cases it is so large that it occupies the greatest part of the abdominal cavity : this is ob- 
 served in tympanitic distension of the large intestine. It is not of uniform caliber 
 throughout, as the following measurements will show. The circumference of the caecum, 
 moderately distended, and taken immediately below the ileo-caecal valve, was found to 
 be eleven inches and three lines in one subject, and nine inches and a half in another ; 
 the right colon in the loins and the right half of the arch were eight inches and nine 
 lines in the first, and five inches some lines in the second subject. The circumference 
 of the left half of the arch of the colon, and of the left lumbar colon, was six inches in 
 the first and five inches and a half in the second. The circumference of the sigmoid 
 flexure was five inches and a quarter ; that of the rectum was three inches until near 
 its termination, where it presented a dilatation four inches in circumference in one, and 
 five inches in the other subject. 
 
 It follows, therefore, that the large intestine, like the small, has an infiindibuliform 
 shape ; it resembles, indeed, two ftmnels, the base of the one corresponding to the 
 caecum, and its apex to the sigmoid flexure, while the base of the other is at the dilated 
 portion of the rectum, and its apex is apphed to that of the first. It is probable that this 
 infundibuliform arrangement has some reference to the passage of the faecal matters. 
 
 It also follows that there is no uniform relation between the diameters of the different 
 portions of the large intestine : thus, a very large caecum and ascending colon may co- 
 exist with a small descending colon In some cases we find in the large intestine con- 
 siderable dilatations, separated from each other by such constrictions that the caliber 
 of the corresponding part of the gut is obliterated. These strangulations from a con- 
 traction of the circular fibres are very different from those produced by organic diseases : 
 they probably take place during life, and may account for the affection known as the 
 windy colic. In some chronic diseases, accompanied with diarrhcea, the large intestine, 
 contracted and containing no gases, is not as large as the small intestine. 
 
 The CcEcum. — The caecum (e, fig. 139), so named because it resembles a cul-de-sac, is 
 the first part of the large intestine The existence of a caecum is one of the numerous 
 indications of the line of separation between the large and the small intestine. Its up- 
 per boundary is altogether arbitrary ; it is determined by a horizontal plane intersecting 
 it immediately above the insertion of the small intestine. It is single in the human sub- 
 ject, but is double in some species of animals. It is situated {c,fig. 161) in the right iliac 
 fossa, and occupies it almost entirely. It is one of the most fixed portions of the ali- 
 mentary canal, for the peritonemn merely passes in front of it, and binds it down into 
 the iliac fossa. It is not, however, so firmly fixed in all subjects ; it is often enveloped 
 by the peritoneum on all sides, and floats, as it were, in the region which it occupies, its 
 capability of motion depending on the looseness of the right lumbar mesocolon. This 
 arrangement of the peritoneum is not necessary, however, to explain the great amoun 
 of displacement which the caecum undergoes in certain cases. It is not uncommon to 
 find it in the cavity of the pelvis : it occasionally enters into the formation of herniae 
 and, what is somewhat remarkable, it has been at least as frequently found in hernia 
 upon the left as upon the right side. 
 
 Its direction, which is in general the same as that of the ascending colon, is not alway 
 vertical a.s may be seen by examining a moderately-distended intestine, but it pass* 
 
379" SPLANCHNOLOGY. 
 
 obliquely upward and to the right side, so that it forms with the colon an obtuse angle 
 projecting on the right side ; and I have even seen it form a right angle with the colon. 
 This arrangement, connected with the obliquity of the plane of the iliac fossa, explains 
 why, when its attachments are relaxed, it has less tendency to be displaced towards the 
 right inguinal ring and femoral arch than to the same parts on the left side. In some 
 subjects, the caecum and its vermiform appendix are applied to the lower part of the 
 small intestine, so that the caecum and the neighbouring part of the colon describe a 
 curve, the concavity of which embraces the lower end of the ileum. 
 
 In size it is generally larger than the portion of the intestine which succeeds it : this, 
 perliaps, depends less upon its primitive conformation than upon the accumulation of 
 faecal matters resulting from the inclined position of this intestine, and from the direc- 
 tion in which its contents are moved. It may be said, as a general rule, that, next to 
 the stomach, the caecum is the largest part of the alimentary canal. There are many 
 individual varieties in the length and capacity of this intestine, in which the faecal mat- 
 ters are liable to be retained. These accumulations occasion great pain ; they have 
 been much studied lately, and have been often mistaken for inflammations. The caecum 
 is very shghtly developed in carnivora, but, on the other hand, it is very large in her- 
 bivora. 
 
 Figure. — ^The caecimi is a sort of rounded ampulla, all the diameters of which arc 
 nearly equal ; it is also sacculated like the rest of the large intestine. Upon it we ob- 
 serve the conamencement of the three longitudinal bands, which I have already noticed : 
 of these, the anterior is, in the caecum, twice as broad as either of the two posterior ; 
 some folds of peritoneum, loaded with fat, which are called fatty appendages {appendices 
 epiploica) ; and, lastly, some protuberances, separated by parallel depressions, an ar- 
 rangement which exists in the colon also, and is produced by the longitudinal bands. 
 
 Relations. — In front, the caecum is in relation with the abdominal parietes, through 
 which it can be felt when it is distended with gases or faecal matters. When the cae- 
 cum is collapsed, the small intestine is often interposed between it and the parietes of 
 the abdomen. 
 
 Behind, it rests upon the iliacus muscle, from which it is separated by the lumbo-iliac 
 fascia. The cellular tissue uniting it to this aponeurosis is extremely loose, and, there- 
 fore, offers no opposition to displacement of the intestine. When the peritoneum forms 
 a complete covering for the caecum, that intestine is, of course, in indirect relation with 
 the iliacus. The vermiform appendix is often turned back behind the caecum. On the 
 inside, the caecum receives the small intestine ; the angle at which they unite (the ileo- 
 csecal angle) varies much. Sometimes the small intestine is inserted at a right angle ; 
 most commonly the angle of incidence is obtuse above and acute below {fig. 160). Some- 
 times the ileum, instead of passing upward, is directed downward, and then the angle 
 of incidence is changed. A circular depression indicates the limit between the two in- 
 testines. Below, upon the free extremity or cul-de-sac of the caecum, is seen the \^r- 
 miform appendix {v), situated behind and on the left side, a few lines below the ileo- 
 caecal angle. 
 
 The arrangement of the internal or mucous surface of the caecum is in accordance with 
 that of its external surface : thus, three projecting ridges correspond with the three lon- 
 gitudinal bands ; some cavities or pouches with the protuberances ; and some transverse 
 projecting folds, forming incomplete septa, which are easily seen in a dried specimen, 
 correspond with the parallel depressions. Upon this surface, to the left and a little be- 
 hind, we also find the ileo-caecal valve (a b,fig. 160), and the orifice (o) of the vermiform 
 appendix (»). 
 
 The Ileo-caecal Valve. — This is also called the valve of Bauhin, from the name of the anat- 
 omist to whom its discovery is attributed, although it had been described before his time. 
 To obtain a perfect knowledge of it, it should be examined upon a fresh specimen under 
 water, and also upon an inflated and dried intestine. 
 
 In a fresh specimen, when viewed from the caecum, it presents the appearance of a 
 projecting cushion, oblong from before backward, and fissured in the same direction. It 
 is a membranous and movable cushion, and was incorrectly compared by Riolanus to the 
 pyloric ring. It has two lips and two commissures ; the two lips are in contact, except 
 during the passage of the contents of the bowels. Two folds, proceeding from the two 
 commissures, one of which is anterior and the other posterior, are lost upon the corre- 
 sponding surfaces of the intestine. The posterior fold is much longer than the anterior ; 
 Morgagni called them ihefrana of the valve. When viewed from the ileum, it presents 
 the appearance of a funnel-shaped cavity, directed upward and to the right side. 
 
 In a dried intestine, the ileo-caecal valve is seen to consist of two prominent valvular 
 segments, projecting into the caecum, so as to form an angular ridge. The upper, or ileo- 
 colic segment {b,fig. 160), is horizontal ; the lower, or ilco-ccecal (a), forms an inclined plane 
 of about 45°, and both are parabolic. The upper segment is fixe J by its adherent convex 
 border to the semicircular line, along which the upper part of the tube of the ileum is 
 united with the colon ; the adherent border of the lower segment, \^ hich is also convex, 
 is continuous with the semicircular hue of junction between the lower half of the ileum 
 
THE INTESTINES. 373 
 
 and the caecum. The free borders of the segments are directed to- 
 wards the right side, and are semilunar ; they are united at their ex- 
 tremities, but in the middle leave between them (between a and h) 
 an opening like a buttonhole, which becomes narrower as the intes- 
 tine is more distended. The diameter of this opening is in proportion 
 to that of the small intestine. The free border of the lower segment 
 is more concave than that of the upper. When examined from the 
 ileum, the valve presents an angular excavation exactly correspond- 
 ing to the projecting edge found in the cavity of the large intestine. 
 The lower surface of the upper valvular segment is slightly concave ; 
 the corresponding surface of the lower segment is slightly convex. 
 
 This double ileo-caecal valve differs widely from the ring of the py- 
 lorus ; it offers no obstruction to the passage of the contents of the 
 small into the large intestine ; but in ordinary cases, it will not per- " 
 
 mit their regurgitation from the latter into the former. The lower or ileo-caecal segment 
 is elevated so as to prevent reflux from the caecum, and the ileo-colic segment becomes 
 depressed, and opposes any return of the contents of the colon. Still, from a great num- 
 ber of experiments which I have performed on this subject, I am satisfied that both wa- 
 ter and air injected into the large intestine most frequently overcome the resistance offer- 
 ed by this valve, though with different degrees of facility in different subjects. This re- 
 gurgitation, however, only takes place with gaseous or liquid matters ; such as have a 
 greater degree of consistence cannot pass back, and therefore the reflux of faecal matter 
 is impossible.* 
 
 Structure. — ^The structure of the ileo-caecal valve was perfectly demonstrated by Albi- 
 nus. If we follow his example, and remove the peritoneal coat from a distended intes- 
 tine, at the point where the ileum enters the large bowel, we shall at once perceive most 
 distinctly that the small intestine seems to sink in there ; and if, by means of careful and 
 gradual force, we attempt to disengage it from the large intestine, it may be drawn out, 
 as it were, from the colon to the length of an inch or an inch and a half; and then, on 
 inspecting the inside of the large intestine, we shall find that the valve has altogether 
 disappeared, and that the ileum communicates with the caecum and colon by a large ap- 
 erture. 
 
 The precise structure of the valve is as follows : it is composed of the circular muscu- 
 lar fibres of the ileum, which are prolonged as far as its free edge ;t of the fibrous coat, 
 and of the mucous membrane. A similar fact has been observed regarding this mucous 
 membrane to one we have already several times noticed in describing the alimentary ca- 
 nal, viz., a sudden change in its character opposite the free margin of the valve. That 
 portion of the membrane which lines the surface turned towards the large intestine has 
 all the characters of the mucous membrane of that bowel, while that lining the surface 
 directed towards the ileum has those of the mucous membrane of the small intestine. 
 The limit between them is generally observed in diseases. 
 
 The Appendix Vermiformis. — The appendix vermiformis {v,figs. 139, 160, 161), so na- 
 med from its resemblance to an earth-worm, commences at the posterior lower and left 
 portion of the caecum, of which it may be considered an appendage {the cacal appendix) ; 
 it resembles a small, hollow, and very narrow cord {duodecies jiascente colo angustior, says 
 Haller). In length and in direction, it presents much variation : its length is from one to 
 six inches. It is somewhat wider at its point of junction with the cascum than in any 
 other part, and is in general about the diameter of a goose-quill. 
 
 Its direction is sometimes vertically downward, sometimes upward, and often tortuous. 
 I have found it spiral, and at other times contained in the substance of the mesentery, 
 parallel to the ileum, and only free at its extremity. In some subjects it is funnel-sha- 
 ped, widening out to become continuous with the caecum, which, in such cases, is very 
 narrow. Its situation and relations are equally variable. Thus, most conmionly, it oc- 
 cupies the right iliac fossa, near the brim of the pelvis : it is attached to the caecum and 
 to the iliac fossa by a triangular or falciform fold of the peritoneum, which extends only 
 to one half of its length, and allows it a greater or less capability of movement. It is still 
 more movable when it is entirely surrounded by the peritoneum, and has no mesentery. 
 From this it may be conceived that it may enter into the formation of herniae, and may 
 be twisted around a knuckle of the small intestine, so as to cause strangulation. It is 
 
 * Nevertheless, if we consider that the large intestine must always be very much distended in order to pro- 
 duce a reflux of gases and liquids, it may be questioned whether the passage of gaseous or liquid matters from 
 the large to the small intestine can take place during life. I have been able to determine the mechani.sm of 
 the resistance oflfered by the valve from the effects of distension. The two segments are turned back, the 
 lower one upward, and the upper one downward ; their corresponding surfaces become convex, and they are 
 pressed together the more and more forcibly in proportion to the amount of distension. In some subjects dis- 
 tension may be carried so far as to rupture the longitudinal bands, and yet not overcome the obstacle. In 
 most cases, the free edge of the lower segment glides from right to left under the upper one, which remaina 
 immovable ; and the gas and liquids escape with more or less facility according to the degree of disturbance 
 in the parts. 
 
 t I The longitudinal muscular fibres and the peritoneal coat pass directly from the small to the large intes- 
 tine, without entering into the formation of the valve.] 
 
374 
 
 SPLANCHNOLOGY. 
 
 often turned back behind the ascending colon between that intestine and the kidney : in 
 one case of this kind, I found the free extremity of the appendix in contact with the lower 
 surface of the liver. I have also once seen it turned up behind the lower end of the 
 -amall intestine, and, at another time, embracing that bowel in front. None of these dif- 
 * ferences, however, depend on the situation of its point of attachment to the csecum, 
 which is always on the left side, below and behind the cul-de-sac, at a short distance 
 from the ileo-caecal valve. 
 
 When divided lengthwise, the cavity within it is seen to be so narrow that the walls 
 are always in contact. A small quantity of mucus is found in it, and it often contains 
 small scybala ; cherry-stones and shot have also been found in it. The whole of its 
 internal surface has a honeycomb appearance, like that at the lower end of the small 
 intestine.* A valve of different size in different subjects, but never sufficiently large to 
 cover the orifice entirely, is found at the point (o. Jig. 160) where the appendix commu- 
 nicates with the caecum. The cavity of the appendix, like the caecum, terminates be- 
 low in a cul-de-sac ; and in this, which is extremely narrow, foreign bodies may be 
 lodged, and may then sometimes become the cause of those spontaneous perforations 
 which are occasionedly seen. The uses of this appendix are edtogether unknown ; in the 
 human subject, it is merely a vestige of an important part in many animals. Haller says 
 that he has twice seen the vermiform appendix obliterated, i. e., without any cavity. I 
 presume that this was the effect of morbid adhesion. Lastly, I once found this appendix 
 as large as the index finger, and two inches in length ; its cavity contained some thick, 
 transparent mucus. The orifice by which it should have conununicated with the caecum 
 was obliterated. 
 
 The Colon. — The colon {kuXvu, to impede, dfg h,fig. 139) constitutes almost the whole 
 of the large intestine. It extends from the caecum to the rectum, and, as we have al- 
 ready seen, there is no line of demarcation between these different parts. In the first 
 part of its course it ascends vertically, then becomes transverse, next descends vertical- 
 ly, and is then curved like the Roman letter S, and becomes continuous with the rectum. 
 From this long course, and also from its direction and numerous relations, the colon has 
 been divided into four portions, viz., the ascending or right lumbar colon, the transverse colon, 
 or arch of the colon, the descending or left lumbar colon, and the iliac colon, or sigmoid flexure. 
 Each of these parts requires a separate description, at least with regard to its relations. 
 Let us first point out the general form of the colon. 
 
 The colon presents a sacculated appearance throughout, which gives it some resem- 
 blance to a chemical apparatus, consisting of a long series of aludels. The sacculi of 
 the colon are arranged in three longitudinal rows, separated by three muscular bands. 
 Each of these rows presents a succession of enlargements and constrictions, or deep 
 grooves, placed across the length of the intestine. These enlargements and grooves 
 are produced by the longitudinal bands, which, bemg much shorter than the intestine, 
 
 cause it to be folded inward upon itself 
 at intervals. It follows, therefore, that 
 division of these bands by means of a 
 bistoury, or, rather, their rupture, from 
 great distension of the gut, should de- 
 stroy this sacculated appearance, and 
 such, indeed, is the result of the exper- 
 iment ; at the same time, the large in- 
 testine becomes twice or three times 
 as long as it was before, and forms a 
 regular cylinder, hke the small intes- 
 tine. An incontestable proof of the 
 relation between the cells of the colon 
 and the muscular bands, is the con- 
 current absence of both in a great num- 
 ber of animals. Lastly, the three rows 
 of sacculi vary much in different sub- 
 jects, and also in different parts of the 
 great intestine. The descending colon 
 and the sigmoid flexure have only two 
 rows of sacculi, and, consequently, two 
 intermediate bands. The sacculi al- 
 most entirely disappear in the sigmoid 
 flexure. 
 
 The Ascending or Right Lumbar Colon 
 (a, figs. 135, 161). — This portion of the 
 colon is bounded below by the caecmn, 
 
 * [Nevertheless, the structure of the mucouf 
 membrane in the two situations is very different 
 (see notes, p. 3T0, 379).] 
 
.THE INTESTINES. 375 
 
 and above by the transverse arch, with which it forms a right angle, near the gall-blad- 
 der. It is more or less firmly held in its place by the peritoneum, which in some sub- 
 jects merely passes in front of it, and in others forms a fold or lumbar mesocolon. The 
 ascending and descending colon may be included among the most fixed portions of the 
 alimentary canal. In front of it are the parietes of the abdomen, from which, excepting 
 when greatly distended, it is separated by the convolutions of the small intestine. Be- 
 hind, it is in immediate relation with the quadratus lumborum and the right kidney, no 
 layer of peritoneum intervening. It is united to these parts externally by loose cellular 
 tissue. This relation accounts for the bursting of abscesses of the kidney into the colon, 
 and explains the possibility of reaching the colon in the lumbar region without wound- 
 ing the peritoneum. On the left side, advantage has been taken of this fact in attempt- 
 ing to form an artificial anus. 
 
 On the inside and on the outside it is in relation with the convolutions of the small intes- 
 tine ; and on the inside also with the psoas muscle, and with the second portion of the 
 duodenum. 
 
 The Transverse Colon, or Arch of the Colon. — This (<) is the longest portion of the large 
 intestine ; it extends from the ascending to the descending colon, from the right to the 
 left hypochondrium, and generally occupies the adjacent borders of the epigastric and 
 umbilical regions. It is not unfrequently found opposite the umbilicus, and even in the 
 hypogastrimn. Its right extremity corresponds to the gall-bladder {g), its left is below 
 the spleen {k). It describes a curve having its convexity directed forward, and its con- 
 cavity backward ; hence the name, arch of the colon. In some subjects it is two or three 
 times its ordinary length, and hence it presents various inflections. I have seen its 
 middle portion descending as low eis the umbilical or hypogastric region, and even reach- 
 ing the brim of the pelvis ; in other cases it descends parallel to, and on the inner side 
 of, the ascending colon, and then passes upward again, or it describes curves of different 
 extent. The arch of the colon is supported by a very remarkable fold of peritoneum, 
 called the transverse mesocolon, which forms a horizontal septum between the small in- 
 testine below, and the stomach, the liver, and the spleen above. The extent of this fold, 
 which is one of the largest of all those formed by the peritoneum, explains the great 
 freedom of the movements of the transverse colon, which, next to the small intestine, 
 is the part of the alimentary canal most frequently found in hernia. 
 
 Relations. — Above, it has relations with the liver (Z), which generally presents a shght 
 depression, corresponding to the angle formed by the ascending and transverse colon ; 
 with the gall-bladder (£), whence the discoloration of the right extremity of the arch 
 from the bile ; it is not rare to find the gall-bladder opening into the colon ; with the 
 stomach («), which projects in front of it when distended, but is separated from it by a 
 considerable interval when empty ; and, lastly, with the lower extremity of the spleen 
 {k). The two anterior layers of the great omentum, which proceed from the greater 
 curvature of the stomach, pass over the arch of the colon without adhering to it. I have 
 seen a large loop of the arch of the colon interposed between the liver and the diaphragm. 
 Below, the arch of the colon corresponds to the convolutions of the small intestine {fig. 
 155). In front, it corresponds to the parietes of the abdomen, beneath which it may 
 sometimes be felt when distended with gas. It is separated from them by the two an- 
 terior layers of the great omentum. The two posterior layers of the great omentum are 
 given off from the middle of its anterior border. Behind, it gives attachment to the 
 transverse mesocolon. 
 
 The Descending or Left Lumbar Colon. — The descending colon {d,figs. 155, 161) so close- 
 ly resembles the ascending portion, both in situation and relations, that we can only re- 
 fer to what has been already stated. We must observe, however, that it is more deeply 
 situated above than the ascending colon, and that it is of less size. Advantage has been 
 taken of its immediate relations behind, with the quadratus lumborum, in the operation 
 for artificial anus in cases of imperforate rectum. It is preferred, for this purpose, to 
 the ascending colon, simply from its proximity to the anus. 
 
 The Iliac Portion, or Sigmoid Flexure, of the Colon. — The sigmoid flexure of the co- 
 lon {f,Jlgs. 155, 161) is situated in the left iliac fossa, and is continuous below with the 
 rectum. The line of demarcation between it and the descending colon is determined by 
 the commencement of a fold of peritoneum, called the iliac mesocolon, or, rather, by the 
 change in the direction of the large intestine, as it appears to detach itself from the pa- 
 rietes of the abdomen, opposite the crest of the ilium. It is continuous with the rectum 
 at the point where it dips into the pelvis, opposite the left sacro-iliac symphysis. But, as 
 it often happens that the lower portion, or even the whole of the sigmoid flexure, is con- 
 tained in the cavity of the pelvis, it may be understood that such a definition is not precise. 
 
 It is retained in its place by a very loose fold of peritoneum, called the iliac mesocolon, 
 and therefore, in some measure, partakes of the mobility of the small intestine. It has 
 been found in almost all the regions of the abdomen, but especially in the sub-umbilical 
 zone. It has been seen in the umbilical region, its first curvature reaching even to the 
 liver. I have met with a case in which the sigmoid flexure extended upward, and the 
 arch of the colon downward to the umbilicus, so that they came in contact with each oth. 
 
376 SPLANCHNOLOGY. 
 
 er ; the large intestine, therefore, corresponded with the whole anterior region of the 
 abdomen, the sigmoid flexure alone occupying the umbilical, the hypogastric, and the 
 left iliac region. 
 
 Should the following disposition, which I have met with several times, be regarded as 
 accidental or congenital 1 Commencing from the descending colon, the sigmoid flexure 
 passed transversely from the left to the right side, on a level with the brim of the pelvis 
 as far as the right iliac fossa, below the caecum, which it turned upward in one case, and 
 pushed in front of itself in another ; the sigmoid flexure then described its two curves 
 either in the right iliac fossa or in the pelvis. These cases, in which the sigmoid flex- 
 ure of the colon alone is transposed, must be carefully distinguished from general trans- 
 position of the viscera. 
 
 The most peculiar character of the sigmoid flexure is its direction. It passes at first 
 upward, in an opposite direction to the descending colon, then descends vertically, and 
 then, curving again, passes to the right or to the left, forward or backward, and becomes 
 continuous with the rectum (r), (the iliac flexure). These several flexures, however, vai7 
 exceedingly : I have seen them very shght ; but then the upper or free portion of the 
 rectum was found decidedly flexuous ; and, indeed, it is difficult to ascertain whether 
 such flexures belong to the rectum or to the displaced sigmoid flexure. • There can be 
 no doubt that this double curve of the colon is connected with its uses as a receptacle 
 for fajcal matters. 
 
 The size of the sigmoid flexure varies considerably. In a case of imperforate anus in 
 an infant, which lived twenty days, it became enormously distended. Retention of the 
 faeces in the adult seldom causes so proportionally great an accumulation in the sigmoid 
 flexure : the rectum is almost entirely the seat of the accumulation. 
 
 Relations. — The sigmoid flexure corresponds to the abdominal parietes in front. When 
 empty, its relations with the latter are indirect, in consequence of the interposition of 
 some convolutions of the small intestine ; when it is distended, they are inmiediate ; 
 and hence we are recommended to make an artificial anus in the sigmoid flexure of the 
 colon, in cases where the rectum is imperforate. It is in contact behind with the iliac 
 fossa, to which it is fiLxed by the mesocolon : hence it can be easily compressed and ex- 
 plored by the fingers, for the purpose of detecting hardened masses of faeces. In the 
 rest of its circumference it is in relation with the convolutions of the small intestine. 
 
 The Internal Surface of the Colon. — On the internal surface of the colon are seen three 
 longitudinal ridges, corresponding to the three muscular bands on its external surface ; 
 three intermediate rows of sacculi, the concavities of which agree exactly with the pro- 
 tuberances on the external surface ; and, lastly, numerous ridges or incomplete septa, 
 dividing the cells of each row from one another, and improperly called valves ; they cor- 
 respond to the grooves or depressions on the external surface. In order to comprehend 
 the arrangement of the cells and the intervening septa, we must examine the large in- 
 testine when moderately distended and dried. If the muscular bands have been previ- 
 ously divided, the cells and septa disappear. 
 
 The internal sacculi, as well as the external protuberances, vary much in different in- 
 dividuals, and even in diflerent parts of the same colon. Thus, there are generally only 
 two rows in the descending colon and the sigmoid flexure, because there are only two 
 muscular bands in those parts. Sometimes, indeed, there are no cells in the sigmoid 
 flexure. Lastly, the internal surface of the large intestine presents some irregular folds, 
 which are completely effaced by distension. 
 
 The Rectum. — The rectum (A i,fig. 139), so called from its direction, which is gener- 
 ally less flexuous than that of the rest of the intestinal canal, is the last portion of the 
 large intestine, and, consequently, of the digestive tube. It commences at the base of 
 the sacrum, and terminates at the anus. It is situated, in the true pelvis, in front of the 
 sacrum and coccyx {r,fig. 161 ; a o',fig. 181). 
 
 We see, then, that the alimentary canal, after having abandoned the vertebral column 
 in order to describe its numerous convolutions, is situated at its termination in front of 
 the lower part of that column, just as, at its commencement, it is applied to the upper 
 part of the same. It is firmly fixed, especially below, where it. is surrounded on all sides 
 by cellular tissue, and is also bound down by the superior pelvic fascia. This part of it 
 cannot, therefore, suffer such displacements as occur in hernia ; but, from its functions 
 as an organ of expulsion, the whole effort of the abdominal inusoles is concentrated upon 
 it, and it is, therefore, liable to displacements of a different kind, viz., to invagination 
 and eversion. 
 
 Its situation, which is in some degree constant, within a bony cavity, having unyield- 
 ing walls, and its relations with the pelvic fascia, place it in conditions altogether pecu- 
 liar to itself; for while the bladder and the uterus, which are also contained in the same 
 cavity, ascend into the abdomen when they are distended, the rectum, in which the fajces 
 are accumulated, dilates entirely within the pelvis, and undi^rfoes no change of position. 
 
 From this fixed condition of the rectum along the miildle of the pelvic cavity, it also 
 follows that, in cases where the gut is denuded by destmrtion of the surrounding cellu- 
 lar tissue, it remains separate from the walls of the pelvis : such is the nature of fistu- 
 
f 
 
 THE INTESTINES. 377 
 
 lae ; and hence the necessity of cutting the rectum, in order to bring it in contact with 
 the walls of the pelvis. 
 
 Direction. — Particular attention should be paid to the direction of this bowel, as an 
 anatomical fact from which practicEd inductions of the greatest interest may be derived. 
 It is not straight, but is curved both in the antero-posterior and lateral directions. 
 
 In the antero-posterior direction it follows the curve of the sacrum and coccyx, to which 
 it is closely applied ; it is, therefore, concave in front and convex behind {see fig. 181). 
 Opposite the apex of the coccyx it bends slightly backward, so as to terminate about an 
 inch in front of that bone. By this very remarkable inflection, it is separated from the 
 ragina in the female, and from the urethra in the male. 
 
 T?ie Lateral Inclination. — On the left side of the base of the sacrum, and opposite the 
 sacro-iliac symphysis, the rectum passes downward, and to the right side, until it reaches 
 the median line opposite the third piece of the sacrum. It then passes forward, still in 
 the median line, and forms a slight curve with the preceding portion. It has been fre- 
 quently said that the lower part of the rectum does not occupy exactly the median hne, 
 but deviates a little to the right : this is not unfrequently the case at the lower part of 
 the sacrum, but it always regains its original position before its termination. 
 
 There are, however, some important varieties in the curvature described by the rec- 
 tum. Thus, it is not uncommon to see the upper part of the gut twisted like an italic <S 
 before reaching the median line ; and in this case, it is difficult to determine whether the 
 twisted portion belongs to the rectum or to the sigmoid flexure of the colon. In several 
 of the cases of unnatural position of the sigmoid flexure, which I have already mention- 
 ed, the rectum commenced on the right side of the base of the sacrum, and passed down- 
 ward, and towards the left side. In one case, where the sigmoid flexure was in its 
 natural position, the rectum passed almost transversely to the right side, as far as the 
 right sacro-iliac symphysis, and then proceeded very obliquely to the left side. The sit- 
 uation of the upper part of the rectum on the left of the median line has been often 
 quoted in explanation of the relative frequency of inclinations of the uterus to the right 
 side, and also of the greater or less amount of difficulty in parturition, according as the 
 occiput of the foetus is turned towards the right or the left. 
 
 Form and Size. — The rectum is cylindrical, not sacculated, and has no bands like those 
 observed in the other portions of the large intestine. Its external surface is covered 
 with a uniform layer of well-marked, fasciculated, longitudinal fibres, which give it some 
 resemblance to the oesophagus. At its commencement, its caliber is somewhat smaller 
 than that of the sigmoid flexure, but it gradually increases towards the lower end. Im- 
 mediately before its termination at the contracted orifice, called the anus, the rectum 
 presents a considerable dilatation, or ampulla, capable of acquiring an enormous size ; so 
 that, in certain cases of retention of the faeces, it has been found occupying the entire 
 cavity of the pelvis. 
 
 Relations. — Behind, the rectum corresponds with the left sacro-iliac sjmiphysis and the 
 curve of the sacrum and coccyx ; it is attached to the sacrum above by means of a fold 
 of peritoneum, called the meso-rectum, and is separated from the sacrum and the sacro- 
 iliac symphysis by the pyriformis muscle, the sacral plexus of nerves, and the hypogas- 
 tric vessels. Those portions of the rectum which project laterally beyond the coccyx 
 are in relation with the levator ani muscles, which form a sort of floor for it. 
 
 In front, the rectum is free in its upper portion, but is adherent below ; its relations 
 vary in the two sexes, and are of the greatest importance in a surgical point of view. 
 
 In the male its upper or free portion {o,fig. 181) corresponds to the posterior surface 
 of the bladder (A), from which it is separated, excepting in cases of retention of urine, or 
 of considerable dilatation of the rectum by convolutions of the small intestines. Its lower 
 or adherent portion is in immediate relation, in the middle line, with the inferior fundus 
 (bas-fond) of the bladder, at the triangular space intercepted between the vesicula; semi- 
 nales (s) ; on each side, it is separated from the bladder by these vesicles. The extent 
 to which it is in contact with this part of the bladder varies in different subjects, and ac- 
 cording as the bladder and rectum are full or empty. 
 
 We shall see in another place that the peritoneum {u u) forms a cul-de-sac of variable 
 depth between them. In some subjects the cul-de-sac extends as far as the prostate, so 
 that the whole of the inferior fundus of the bladder is covered by it. 
 
 In front of the inferior fundus of the bladder the rectum is intimately united to the 
 prostate {i). In some cases the prostate projects beyond the rectum, on one or both 
 sides ; in other cases the rectum projects beyond the prostate, on one or other, or both 
 sides, and receives the gland, as it were, in a groove. 
 
 The rectum has also relations with the membranous portion of the urethra (c), but, on 
 account of its inflection backward, it is separated from it by a triangular space, the base 
 of which is directed downward and forward, and the apex upward and backward. 
 
 The practical inferences to be drawn from these relations are these : that the bladder 
 projects into the rectum in cases of retention of urine ; that the bladder can be explored 
 from the rectum, and may be punctured and cut for the extraction of stone ; that the 
 finger passed into the rectum can assist in the introduction of the catheter, and in ex- 
 
 Bb B 
 
378 SPLANCHNOLOGY. 
 
 amination of the prostate ; that the rectum must be emptied before performing the lateral 
 operation for stone ; and, lastly, that the membranous portion of the urethra may be 
 opened without injuring this bowel. 
 
 In the female, the free portion of the rectum corresponds with the broad ligament, the 
 left ovary and Fallopian tube, the uterus, and the vagina. The peritoneum forms a cul- 
 de-sac between the vagina and the rectum, analogous to that already described between 
 the bladder and the rectum in the male, and subject to the same varieties. When the 
 uterus and the rectum are empty, a certain number of convolutions of the small intestine 
 are always interposed between the rectum and the vagina ; and, therefore, in lacerations 
 of the posterior wall of the vagina, the small intestines escape through the wound. 
 
 The uterus and vagina are not unfrequently found deviating to the left side, while the 
 rectum deviates to the right, and then the free portion of the latter corresponds to the 
 right broad ligament and ovary. Lastly, in retroversion of the uterus, which is so com- 
 mon, the fundus of that organ rests upon the rectum. 
 
 The inferior or adherent portion of the rectum is intimately united to the vagina : hence 
 vaginal cancer frequently extends into the rectum ; below, on account of its inflection 
 backward, it is separated from the vagina in the same way as from the urethra in the 
 male, by a triangular space, the base of which is directed downward, and forms the 
 perineum of the female. 
 
 On the sides, the free portion of the rectum corresponds to the convolutions of the in- 
 testines ; the adherent portion is surrounded by adipose cellular tissue, which is nowhere 
 more clearly intended to fill up intermediate spaces ; the absorption or destruction of 
 this tissue is an important circumstance in diseases of the anus. 
 
 The internal surface of the rectum is remarkable for some longitudined folds, which are 
 obliterated by distension, and somewhat resemble the longitudinal folds of the cesophagus. 
 These folds, which have been inappropriately termed the columns of the rectum, are in- 
 tersected by other semicircular folds, also effaced by distension. This internal surface 
 presents, moreover, a dilatation corresponding to the enlargement seen from without, 
 immediately above the anus. 
 
 Structure of the Large Intestine. — The same number of coats exist in the large as in the 
 small intestine, but they present certain peculiarities in arrangement, of which some are 
 common to the whole bowel, while others exist only in particular parts. 
 
 The Peritoneal Coat. — The peritoneum does not, in general, form so complete a cover- 
 ing for the large as for the small intestine. Moreover, it forms a great number of dupli- 
 catures on the surface of the bowel, which usually contain fat, and are called the fatty 
 appendices {appendices epiploica). They are not constant, either in number, size, or 
 length, but are sometimes arranged in regular series. Some of them are so long that 
 they may form the contents of a hernial sac, or may even occasion strsmgulation, by 
 forming a ring around the intestines ;' they are seldom entirely absent. They become less- 
 ened when the gut is distended, and are elongated by its contraction. They are sometimes 
 loaded with an immense quantity of fat, of which they may be considered reservoirs. They 
 are found along the whole of the large intestine, including the free portion of the rectum. 
 
 The peritoneum often envelops the whole of the caecum ; at other times it does not 
 cover it behind. Most commonly it forms a fold, or mesentery, for the vermiform ap- 
 pendix. It only passes in front of the ascending and descending colon, which are al- 
 ways uncovered behind. It invests the whole of the transverse arch, excepting a trian- 
 gular space behind corresponding to the transverse mesocolon, and in another triangu- 
 lar space in front corresponding to the great omentum. It completely surrounds the sig- 
 moid flexure, excepting in a small space behind, corresponding to the iliac mesocolon. 
 Lastly, at the upper part of the rectum, it is arranged in a similar manner, and then 
 merely passes in front of that bowel, the lowest portion of which is entirely devoid of a 
 peritoneal covering, and is surrounded by a large quantity of adipose tissue. 
 
 From the arrangement of the peritoneum upon the large intestine, it follows that the 
 latter is more favourably circumstanced than the small intestine for assuming a large 
 size ; and, also, that it may be penetrated in many places without injuring the peritoneum. 
 
 The Muscular Coat. — As in the small intestine, this coat consists of a circular and a 
 longitudinal set of fibres. 
 
 The circular fibres form the deep layer, and are arranged as in the small intestine ; the 
 longitudinal fibres, which constitute the superficial layer, are not disposed equally around 
 the bowel, but are collected into three bands, which we have already noticed. These 
 bands have the pearly appearance of ligaments when seen through the peritoneal cover- 
 ing ;* they are continuous with the longitudinal fibres of the appendix vermiformis. The 
 anterior is the largest ; it becomes inferior along the arch of the colon, and again ante- 
 rior upon the descending colon and sigmoid flexure, spreading out upon the latter. Of 
 the posterior bands, which are narrower, one is external and the other internal ; they 
 become superior on the arch of the colon, and again posterior upon the descending colon 
 and sigmoid flexure, upon the latter of which they are often blended into one. I have 
 
 * [They are involuntary muscular fibres ; in the lower part of the rectum some transversely striated fibres 
 are found.] 
 
THE INTESTINES. 379 
 
 already said that these bands, being not more than one third, or, at most, one half the 
 length of the large intestine, occasion its puckering, and arrangement into sacculi and 
 intervening depressions. 
 
 The muscular coat is remarkably modified in the rectum. In the sigmoid flexure the 
 longitudinal fibres become scattered, and at its termination surround the whole intestine ; 
 but this arrangement exists more particularly in the rectum, where they present the ap- 
 pearance of thick fasciculi, forming an uninterrupted covering (r,Jig. 161). The deep or 
 circular layer of the rectum is much thicker than that of any other part of the alimenta- 
 ry caucil, excepting the ossophagus ; it may be separated into distinct rings, the lowest 
 of which is so distinct that it has been described as a particular muscle, under the name 
 of the sphincter internus. It is arranged in precisely the same way as the corresponding 
 coat of the oesophagus, but is not so thick : this difference depends upon the uses of the 
 two canals, the oesophagus being intended to convey the food rapidly downward, while 
 the rectum is assisted by the abdominal muscles. When the rectum is empty, it contracts 
 upon itself like the oesophagus, and its walls are in contact. 
 
 The fibrous coat of the large intestine offers no peculiar characters. 
 
 The mucous coat of the large intestine has no valves : the semilunar crests, or ridges 
 which separate the cells of the colon, are formed by all the coats. The irregular folds 
 or wrinkles observed on this membrane are completely effaced by distension. The mu- 
 cous membrane is not unfrequently protruded through the muscular fibres, so as to form 
 small sacs having narrow necks, and containing masses of indurated faces. At first 
 sight such sacs resemble a varix. They are very conmion in the aged, and are probably 
 the result of habitual constipation. 
 
 When examined with the microscope and under water, in the same manner as the 
 mucous membrane of the small intestine, the inner surface of the large intestine is seen 
 to have no villi, but we find exactly the same appearance as in the mucous membrane 
 of the stomach, viz., an alveolar or honeycomb arrangement.* The openings or pores 
 of this mucous membrane are innumerable ; and, supposing that they assist both in ex- 
 halation and absorption, it may be conceived with what rapidity these processes must 
 be carried on in the large intestine. It is also studded with a number of follicles (tan- 
 quam stellae firmamenti, Peyer), which are depressed and perforated in the centre,* and 
 in a great number of subjects, especially in the old, have a black colour. These follicles 
 are never collected into patches, as in the smaU intestine, but are always solitary. They 
 are often inflamed, though the rest of the membrane is healthy. 
 
 It is easy, then, to distinguish the large from the small intestine, simply from the char- 
 acters of its mucous membrane. The hmit between the two is at the free margin of the 
 ileo-caecal valve ; aU preceding this has the characters of the mucous lining of the small, 
 all that comes after, of that of the large intestine. 
 
 We find dense patches of follicles in the vermiform appendix, the whole of which is 
 sometimes Mned with them. 
 
 The mucous membrane is more loosely united to the fibrous coat in the rectum than 
 in any other part of the large intestine. This looseness is most marked at its lower 
 part, and hence a protrusion of this membrane only may occur, as in the oesophagus ; 
 and this must be carefully distinguished from prolapsus of the entire rectum. I should 
 also remark, that the capillary veins are much developed at the lower part of the rectum, 
 and, when much larger than usual, constitute what are called hemorrhoidal tumours. 
 
 Vessels and Nerves. — The arteries of the caecum, the vermiform appendix, the ascend- 
 ing colon, and the right half of the arch, are supplied by the superior mesenteric ; the 
 rest of the colon and the rectum receive blood from the inferior mesenteric. The rec- 
 tum also receives a branch from the internal iliac, called the middle hemorrhoidal, and 
 a branch from the internal pudic, called the inferior hemorrhoidal. Some small ramifi- 
 cations are also furnished to the great intestine by the gastro-epiploic, splenic, capsular, 
 and spermatic arteries. The rectum exceeds all other parts of the large intestine in the 
 number and size of its arteries, and, therefore, operations upon the lower part of that 
 bowel are often followed by serious hemorrhage. 
 
 The veins, which bear the same name and follow the same course as the arteries, concur 
 in the formation of the great and small mesenteric or mesaraic veins, which terminate 
 in the vena portae. p. jgg 
 
 The lympliatic vessels are very numerous, and terminate in the 
 
 * [In the stomach this character is due to the presence of the alveoli, in the bot- 
 tom of which the perpendicular tubuli open. In the large intestine, however, 
 there are no pits ; but the alveolar appearance is produced by the openings of nu- 
 merous tubes, analogous in form and direction to the tubuli of the stomach, and to 
 the crypts of Lieburkuhn in the small intestine. 
 
 The follicles of the large intestine diifer from the solitary glands of the jejunum 
 and ileum, in being always open. Each follicle is much dilated below, but has a 
 narrow oriiice. lu Jig. 162, the upper drawing represents a vertical section of a 
 follicle (magnified), surrounded by the perpendicular tubes ; the lower is a magni- 
 fied superficial view, showing the depression and opening in the centre, and the _=__ 
 orifices of the surrounding tubes. Magnified. 
 
 The epithelium of this mucous membrane is cylindrical or columnar.] r- ■■ 
 
380 
 
 SPLANCHNOLOGY. 
 
 glands situated along the attached border of the intestine ; the large intestine is also 
 possessed of lacteals, but they are less evident than in the small intestine. 
 
 The nerves are derived from the solar plexus, and form plexuses along the arteries ; 
 they all belong to the ganglionic system. The rectum alone receives additional nerves 
 from the cerebro-spinal system, viz., from the hypogastric and sacral plexuses. The 
 presence of these two sets of nerves has reference to the functions of the bowel, which 
 are partly involuntary and partly subject to the influence of the will. 
 
 The Anus. — The word anus, borrowed from the Latin, signifies the lower orifice of the 
 alimentary canal (the anal orifice) ; it is a narrow but dilatable opening, through which 
 the faeces are expelled. 
 
 It is situated in the median line, about an inch in front of the point of the coccyx, at 
 the back part of the perineum, between the tuberosities of the ischium, and at the bot- 
 tom of the fissure between the buttocks. The skin around the borders of this orifice, 
 wfiich is constantly closed, contains a great number of sebaceous follicles, and is cover- 
 ed with hair in the male ; it passes deeply into the orifice, to become continuous with 
 the mucous membrane, and presents a great number of radiated folds, which are effaced 
 during dilatation. The point at which it becomes continuous with the mucous mem- 
 brane is deserving of notice : it is within the rectum, at the distance of some lines from 
 the anus properly so called, and is marked by a waved line, which forms a series of 
 arches or festoons, having their concavities directed upward. Sometimes there are 
 small pouches in the situation of these arches, opening upward. From the angles at 
 which the arches unite, some mucous folds proceed, and small foreign bodies, detached 
 from the faeces, are often retained in the culs-de-sac, and become the causes of fistulae. 
 
 Structure of the Anus. — The anus, intended as it is to prevent the revolting inconve- 
 nience of a constant and involuntary escape of the faeces, consists essentially of a sphinc- 
 ter muscle, which is antagonized, not only by the proper dilator, viz., the levator ani, with 
 which I connect the ischio-coccygeus, but also by the diaphragm and the abdominal mus- 
 cles. The absence of a sphincter is the great evil of every artificial anus. A fourth 
 muscle, the transversalis perinei, must also be included among the muscles of the anus. 
 
 The skin and the mucous membrane which cover these muscles are remarkable for the 
 great development of the erectile tissue, which forms the basis of all tegumentary mem- 
 branes. The terminal branches of the hemorrhoidal arteries are extended upon this 
 portion of the skin and mucous membrane. From this erectile, and, therefore, vascular 
 tissue, arise a great number of winding, twisted, and plexiform veins, which form the 
 lowest roots of the vena portae. A considerable number of cerebro-spinal and ganglionic 
 nerves, derived from the sacral plexus and the hypogastric nervous centre, are distribu- 
 ted around this orifice. Lastly, there are mucous crypts, or, rather, glands, a vestige 
 of the highly-developed glandular organ found in some animals. 
 
 Muscles of the Anus. — We now proceed to the description of the muscles of the anus, 
 which are six in number, viz., two single muscles, the sphincter and the transversalis pe- 
 rinei ; and two pairs, the levatores ani and the ischio-coccygei, which, in fact, form but 
 one muscle. The sphincter intcmus of authors is nothing more than the last ring of the 
 circular fibres of the rectiun. 
 
 The Sphincter Ani. 
 Dissection. — Remove carefully the corrugated skin which covers the anal region ; pro- 
 long the dissection backward as far as the coccyx, and forward to the scrotum in the 
 male, and the vulva in the female. It is not sufficient to expose the lower ring of the 
 sphincter ; the adipose tissue, which surrounds the lower part of the rectum, should be 
 removed on each side. It is well to stuff the lower part of the rectum preparatory to 
 this dissection, as well as that of the muscles of the perineum. 
 
 The sphincter ani {a, fig. 163) is an orbicular muscle, situated around the lower end of 
 j^^. 163. the rectum. It is not a simple ring, but 
 
 a muscular zone of nearly an inch in 
 width. Its form is an ellipse, much elon- 
 gated from before backward, and tenni- 
 nating in a point in front and behind. 
 The fibres which constitute the lower- 
 most ring of the muscle arise from the 
 sub-cutaneous cellular tissue in front of 
 the coccyx, in the same manner as other 
 cutaneous muscles ; those which fonn 
 the upper rings arise from a sort of 
 fibrous tissue given off from the point 
 of the coccyx. From these points the 
 fleshy fibres proceed forward, and fonn 
 a semi-ellipse on each side, composed 
 of pa'rllel and superimposed muscular 
 rings, which terminate in front of the anus in the folldwing manner : The lower rings 
 
THE INTESTINES. 381 
 
 in the sub-cutaneous cellular tissue, the upper rings in the sort of fibrous raph^, which 
 gives origin to the bulbo-cavemosus. 
 
 Relations. — The internal surface of the sphincter embraces the lower part of the rec- 
 tum, the lowest circular fibres of which are seen within the sphincter, and are distin- 
 guished from it by their paleness. They constitute the internal sphincter. Its external 
 surface is in relation with the adipose tissue of the pelvis. Its upper border is continu- 
 ous with the antero-posterior fibres of the levaotr ani ; so that it is very difficult to es- 
 tablish the limit between them. 
 
 Its inferior border projects a little below the lowest annular fibres of the rectum, and 
 only adheres to the skin by loose cellular tissue, which is continuous with the dartos. 
 
 Action. — It is a constrictor of the anus. The contraction of the body of the muscle 
 closes the lower part of the rectum ; the constriction produced by the inferior ring oc- 
 curs below that bowel. 
 
 The Transversus Perinei. 
 
 Dissection. — Remove with care the sub-cutaneous cellular tissue in front and upon the 
 sides of the anus. 
 
 The transversus perinei (b) is situated almost transversely in front of the anus. It 
 arises from the internal lip of the tuberosity of the ischium, immediately above the ischio- 
 cavemosus {erector penis), by a broad and thin tendon, which is soon succeeded by fleshy 
 fibres. These pass inward and a little forward, on to the anterior surface of the rectum, 
 where they are usually described as becoming blended with those of the opposite side 
 in a fibrous raphe, common both to the transversi, the sphincter, and the bulbo-cavernosi 
 {acceleratores urinoe). This does not appear to me to be the exact termination. I have 
 seen this muscle evidently continuous with that of the opposite side, after having trav- 
 ersed the anterior extremity of the sphincter. According to this, the two transversi 
 would constitute a single muscle, forming a half ring, the concavity of which, being di- 
 rected backward, would embrace the anterior part of the rectum, an arrangement well 
 calculated to assist in expulsion of the faeces. 
 
 Relations. — This muscle is placed at the boundary between the anal and perineal re- 
 gions. It forms the posterior side of a triangle, of which the outer side is formed by 
 the ischio-cavernosus (c), and the inner by the bulbo-cavemosus (d). It is sub-cutaneous, 
 excepting in the median line, and is in relation above with the levator ani. 
 
 Action. — It tends to compress and force the anterior against the posterior surface of 
 the rectum, which we shall see is pushed forward by the levator ani. It therefore as- 
 sists powerfully in defsDcation. 
 
 The Ischio-coccygeus and Levator Ani 
 
 Dissection. — These muscles must be studied both from the perineum and from the in- 
 terior of the pelvis. In the perineum : remove the adipose tissue, which occupies the 
 interval between the rectum and the obturator internus ; in order to expose the whole 
 of the ischio-coccygeus, cut the lower edge of the glutaeus maximus, and carefully divide 
 the great and small sacro-sciatic ligaments. In the pelvis : remove the peritoneum li- 
 ning the sides of that cavity ; remove the superior pelvic fascia which covers these mus- 
 cles, and trace them very carefully backward and upon the sides of the rectum, the blad- 
 der, and the prostate gland. 
 
 The ischio-coccygeus and the levator ani constitute the floor of the pelvis. They form 
 an uninterrupted muscular plane, from the lower border of the pyriformis muscle to the 
 arch of the pubes. The ischio-coccygeus includes that portion which is inserted into the 
 sides of the coccyx: the remainder is the levator ani. 
 
 The Ischio-coccygeus, or Coccygeus. 
 
 This is a flat, triangular, or, rather, a radiated muscle (o), situated at the lower part 
 of the pelvis, in front of the sacro-sciatic ligaments. It arises from the sides and sum- 
 mit of the spine of the ischium, from the anterior surface of the lesser sacro-sciatic lig- 
 ament, and often from the posterior part of the pelvic feiscia ; it passes in a radiated 
 manner to the border of the coccyx and the lower part of the border of the sacrum. All 
 these attachments are eflfected by aponeurotic fibres, to which the fleshy fibres succeed. 
 In this respect its structure has considerable analogy with that of the intercostal mus- 
 cles, the tendinous portion exceeding the muscular. 
 
 Relations. — Its upper surface {o,fig. Ill) is slightly concave, and corresponds to the 
 rectum ; its Zoicer surface {fig. 163) is slightly convex, and is in relation with the sacro- 
 sciatic ligaments and the glutaeus maximus ; its posterior margin is applied to the lower 
 border of the pyriformis ; its anterior margin is continuous, without any line of demar 
 cation, with the posterior margin of the levator ani (n), from which muscle it can be dis- 
 tinguished merely by its tendinous structure. 
 
 Action. — It assists in forming the floor of the pelvis. It tends to draw the coccyx to 
 its own side : when the muscles of both sides act together, the coccyx is fixed, and can- 
 not be thrown backward. It acts, therefore, in defalcation. The name levator coccygis, 
 which was given to it by Morgagni, is altogether inapolicable. 
 
SS2 SPLANCHNOLOGY. 
 
 The Levator Ani. ' "''*•' 
 
 This muscle («), so called from one of its chief uses, is situated in the cavity of the 
 pelvis, and with its fellow forms a sort of muscular floor, which, in many respects, re- 
 sembles that formed by the diaphragm. It is thin, curved, and quadrilateral, narrow in 
 front, and broad behind. 
 
 It arises, by its fixed or upper attachments, in front, from the pubis, at the side of, and 
 sometimes even from the symphysis ; behind, from the anterior border of the spine of the 
 ischium, and in the interval between these extreme points from the upper part of the ob- 
 turator foramen, and from the brim of the pelvis. 
 
 Its movable attachments are to the side of the prostate, the bladder, and the rectum, to 
 the point of the coccyx, and to the fibrous raphe extending from that point to the sphinc- 
 ter. The fibres arising from the symphysis pubis are concealed by the pubio-prostatic 
 ligament ;* they are few in number, short, and directed inward, backward, and down- 
 ward, to form a bundle (the prostatic), which was described by Santorini as the levator 
 prostatcB, and by Winslow as le prostatique supirieur. The fibres arising from the spine 
 of the ischium are blended at their origin with those of the coccygeus, and pass trans- 
 versely inward to the point of the coccyx. The origins from the upper pai-t of the obtu- 
 rator foramen and from the brim of the pelvis take place by means of the pelvic apo- 
 neurosis, which divides and receives the muscle between its two layers (i. e., the supe- 
 rior pelvic and the obturator fasciae). These fibres, the hindermost of which are the 
 longest, all pass inward, describe a curve having its concavity directed upward, and are 
 divided into the vesical, anal, and pnz-coccygeal. The vesical fibres pass upon the sides 
 of the inferior fundus (bos-fond) of the bladder. I have never seen them terminate on 
 the vesiculae seminales. The anal fibres having reached the sides of the rectum, above 
 the sphincter, pass backward, and meet behind the bowel. They constitute a half ring 
 on each side, prolonging the sphincter upward, without any distinct line of demarcation. 
 The pra-coccygeal fibres are directed backward, and form a thick fleshy layer, occupying 
 the interval between the coccyx and the sphincter, and completing the lower wall or floor 
 of the pelvis. In the female there are also vaginal fibres. 
 
 Relations. — Its upper or internal surface is covered by the superior pelvic fascia, which 
 separates it from the peritoneum and the organs contained in the pelvis. The obturator 
 fascia intervenes between its lower or external surface and the internal obturator mus- 
 cle, from which it is separated below by a large triangular space, narrow above and broad 
 below, and filled with adipose tissue. Its posterior part is in relation with the glutaeus. 
 
 Action. — It serves as a muscular floor for the pelvis. It raises the prostate, the infe- 
 rior fundus of the bladder and the anus, and counteracts the effect of the diaphragm and 
 abdominal muscles during violent exertions. It assists powerfully in the expulsion of 
 the urine, the seminal fluid, and the faeces. 
 
 As the largest portion of the muscle occupies the sides and the back of the rectum, its 
 especial use is to expel the contents of that bowel : this is effected by the pree-coccygeal 
 fibres of both muscles elevating the rectum, and by their anal fibres drawing it forward 
 and upward, and compressing it on the sides. 
 
 Functions of the Large Intestine. — In the large intestine, the alimentary substances ac- 
 quire the odour and all the other characters of the faeces ; any remaining nutritious mat- 
 ter or chyle which they may contain is absorbed, and they become hardened and mould- 
 ed in the cells of the colon. Absorption is sufficiently active in the large intestine to 
 enable life to be supported for a considerable period by means of nutritive enemata, in 
 persons who cannot receive food into the stomach. The large intestine acts also as a 
 reservoir ; its long course, its curvatures, and its easily yielding character, enable it to 
 contain a great quantity of matter, and prevent the inconvenience of constant defaecation. 
 
 The appendix vermiformis has no use in man ; it is merely the trace of a largely-de- 
 veloped intestine in herbivorous animals. 
 
 The rectum is the final reservoir, and one of the agents in the expulsion of the faeces, 
 the presence of which gives rise to a sensation that informs us of the necessity for evac- 
 uating them. The sphincter, in general, opposes this evacuation, until it is determined 
 upon by the will. The expulsion is effected by the action of the rectum, assisted by the 
 diaphragm and the abdominal muscles. 
 
 Development of the Intestinal Canal. 
 
 The development of the intestinal canal offers two subjects for consideration, viz., the 
 relations existing between it and that portion of the foetal membranes called the vesicula 
 umbilicalis; and the development of the canal itself, independently of that vesicle. 
 
 In reference to the first point, the anatomy of the human foetus is still involved in much 
 obscurity, authorities being divided in opinion on the subject. Without entering here 
 into a discussion which belongs to a higher department of anatomy, I would observe, that 
 
 * [/. e., by the anterior folds of the Teeto-vesical fascia, from which the fibres in question partly arise, and 
 by which they are separated from the levator ani : the posterior layer of the triangular ligament is in relation 
 ■with them in front.] 
 
THE INTESTINES. 
 
 the principal arguments adduced by those who admit the communication between the 
 intestinal canal and the vesicula umbilicalis are drawn from analogy, and especially from 
 what occurs in oviparous animals, whose viteUine membrane is regarded as analogous 
 to the umbihcal vesicle, and in which the most evident communication exists at all sta- 
 ges of foetal existence. 
 
 I would observe, also, that these same anatomists are not agreed respecting the point 
 at which this communication occurs. According to Oken, it is at the junction of the 
 small with the large intestine :* according to Meckel, it is at the lower part of the small 
 intestine, and the diverticula so frequently observed in this place are vestiges of the ca- 
 nal of communication. The last-named anatomist, after having discussed all the argu- 
 ments on either side of the question, concludes thus : "I think, then, that we must at 
 present admit a continuity of substance between the umbilical vesicle and the intestinal 
 canal, without pretending to decide whether the cavities of these two organs open into 
 each other" {Manual d'Anatomie, torn, iii., p. 416, trad, par MM. jourdan et Breschet; 
 But the communication of the cavities is evidently the entire question. 
 
 The arguments of those who deny the existence of a communication in the human foetus 
 and mammalia are founded upon direct observation. I must say, with Emmert, Cuvier, 
 and others, that I have never detected this communication ; and though I am far from 
 denying it altogether, yet I consider that facts are still wanting to prove its existence.! 
 
 The development of the intestinal canal itself presents, besides some questions yet un- 
 determined, certain positive facts, concerning which there can be no dispute. One of 
 the undetermined questions relates to the mode in which the intestine is formed. Is the 
 digestive tube originally an oblong vesicle, which becomes elongated, at the same time, 
 at both its cephaUc and its coccygeal extremities, both being at first imperforate, but af- 
 terward opening so as to form the mouth and anus ] Does it at first resemble a groove 
 open in front, as Wolf has shown to be the case in birds ; or is it developed from two 
 lateral halves, subsequently united together, according to the opinion of M. SerresT Is 
 the intestinal caned formed from one, or from several centres of development 1 Is it de- 
 veloped from several pieces, which afterward meet each other, so to speak 1 and are any 
 grounds for this opinion afforded by the absence of different portions of the canal in 
 acephalous monsters, or the occasional existence of septa in different parts of its extent ] 
 I think not. 
 
 Upon the whole, these microscopical investigations into the first traces of the devel- 
 opment of organs are still involved in great obscurity ; and I must say that, whenever I 
 have been able to discern the intestinal canal, it has appeared to me to form a complete 
 cylinder, t Another question, which yet remains undetermined, relates to the situation 
 of the intestine in the early periods of intra-uterine existence. It is at first situated, as 
 some authors believe, in front of the vertebral column ; or, rather, as others imagine, in 
 that portion of the cord which is next the umbilicus. 
 
 Embryologists agree in stating that, in the earliest periods of its development, the in- 
 testinal canal is not contained in the abdominal cavity, but only its two extremities ; all 
 the intermediate part, i. e., almost the whole of the canal, is situated within the umbili- 
 cal cord, which at that time is very considerably enlarged. The whole intestinal canal is 
 not included in the cavity of the abdomen until towards the middle of the third month. 
 
 This fact is quoted in explanation of congenital umbilical hernia, which would be con- 
 sidered merely an arrest of development. I must here remark, that this situation of the 
 intestines, in a cavity formed within the umbiUcal cord, does not seem to me to have 
 been clearly established ; that there are a great number of cases where no such arrange- 
 ment exists ; that in other cases there is only a loop of the intestine in the substance of 
 the cord ; and, lastly, that the cases in which such an arrangement has been observed, 
 if not examples of actual disease, may at least be regarded as instances in which the de- 
 velopment of the anterior wall of the abdomen had been retarded.<J 
 
 Dimensions of the Intestinal Canal. — The earlier the period of development, the shorter 
 and narrower is the intestinal canal. Its length at first appears to correspond to that of 
 the vertebral column, a relation which is natural and permanent in a great number of the 
 lower animals. The canal soon becomes flexuous, and its windings become more nu- 
 merous in proportion as it increases in length. From the third to the fourth month, its 
 curves are analogous to those which it subsequently describes : at the sixth month, the 
 due proportion between the different parts of the canal is established. At the earlier 
 periods, the small intestine has a much greater caliber in proportion to the large intes- 
 tine than it afterward presents ; and, on the other hand, the large intestine is relatively 
 longer than at subsequent periods. 
 
 The division into the large and the small intestines does not exist at first. There is 
 
 * The Termiform appendix and the caecum are the remains of this communication, according to Oken. 
 
 t [The communication has been distinctly seen and described by Dr. Allen Thomson. — (Edin. Med. and 
 Surg. Journ., cxl., p. 132.)] 
 
 } [In the ovum, No. II., described by Dr. A. Thomson {loc. cit.), the future alimentary canal has the forn 
 of a groove.] 
 
 If [The presence of a portion of the intestinal canal within the umbilical cord, at some period of development 
 is constant not only in man, but in several quadrupeds, and cannot be merely accidental.] 
 
SPLANCHNOLOGY. 
 
 no ileo-caecal valve, no caecum, and no appendix vermiformis ; but these three means of 
 distinction appear simultaneously from the second to the third month.* The caecum and 
 the vermiform appendix are not distinct from each other, but present the appearance of 
 a sort of funnel. The appendix, though at first small, is gradually developed, and be- 
 comes proportionally greater than it is afterward ; its caliber is nearly one half that of 
 the small intestine. If it be not quite correct to say, with Hallcr, that the caecum does 
 not exist in the foetus, yet it must be admitted that, at this period of existence, it is no- 
 thing more than the expanded base of the vermiform appendix ; and the development 
 which it acquires after birth may, to a certain degree, be regarded as the mechanical ef 
 feet of the weight of the faecal matters in dilating its cells. The anterior cells of the 
 ceecum, on account of its vertical position, undergo a relatively greater amount of dilata- 
 tion ; and from this the vermiform appendix, which corresponded at first to the centre 
 of the lower end of the caecum, is turned backward, inward, and to the left side, towards 
 the ileum. The caecum and the appendix do not occupy the right iliac fossa until the 
 fourth or fifth month ; before that time they are situated in the neighbourhood of the um- 
 bilicus. For the first four or five months of intra-uterine life, the large intestine is not 
 sacculated ; so that its external surface is exactly similar to that of the small intestine, 
 the only means of distinguishing one from the other being the situation of the vermiform 
 appendix. About the fifth month, according to Morgagni, the three longitudinal depres- 
 sions, and the transverse folds or depressions and intermediate protuberances, make 
 their appearance simultaneously. These characters are first observed in the transverse 
 arch of the colon. 
 
 The valvulae conniventes of the small intestine do not appear until about the seventh 
 month, and they are very slightly developed at birth. It is not uninteresting to remark, 
 that the condition of the foetus, in this respect, resembles that of animals, which never 
 have valvulae conniventes. The villi, however, can be observed as early as the third 
 month. Meckel considers that they are developed from folds of the mucous membrane, 
 the surfaces of which become notched. At the same period, according to that author, 
 villi are very apparent in the large intestine ; but, after the seventh month, they diminish 
 in number and size, while those of the small intestine remain, even if they do not increase. 
 
 At first it is impossible to distinguish the several coats of the intestine ; the serous and 
 the mucous membrane can alone be recognised. The intestine is perfectly transparent. 
 
 The great omentum first appears during the third month, along the convex edge of the 
 stomach, like a small and very thin border. Fat is never found within it before birth ; 
 nor are the appendices epiploicae developed until after that event. 
 
 At birth, the intestinal canal presents the same characters as it afterward possesses. 
 The small intestine is already provided with rudimentary valvulae conniventes, with well- 
 marked villi, and with very evident solitary and agminated glands. The large intestine, 
 which is much developed, is distended with meconium ; the caecum is shorter than it 
 afterward becomes, the vermiform appendix is larger, and the ileo-caecal valve has the 
 same appearance as in the adult. The mucous membrane of the large intestine is al- 
 ready characterized by its solitary follicles and alveolar appearance. 
 
 In the large intestine of the foetus, we find, instead of faecal matter, a thick, viscid in- 
 odorous, and dark-green substance, which fills the bowel more or less completely. This 
 is the meconium, so called from the Greek word /i^kuv, a poppy, because it bears some 
 resemblance in colour and consistence to the juice of that plant. Its quantity increases 
 towards the period of birth. The time at which it first appears has not been ascertained : 
 I have found it in foetuses of four or four and a half months, but then it only occupied the 
 rectum. From the seventh to the ninth month it is accumulated in the sigmoid flexure, 
 and diminishes in quantity towards the ileo-caecal valve. The vermiform appendix is 
 not unfrequently found distended with this matter. The small intestine also contains 
 a mucous substance ; but it is less abundant and less viscid, sometimes colourless, and 
 sometimes yellowish or greenish. 
 
 The changes which take place in the intestinal canal after birth, affecting its caliber, 
 its situation, and its length, appear to me to depend upon its being more or less distended 
 with gas and faecal matters, and on its being displaced in consequence of adhesions, in- 
 crease of size, or displacement of other organs. I have proved that in females who have 
 had children, the intestines present more varieties in situation than in males. We may 
 add, that these differences in position are much more frequently observed in the large 
 than in the small intestine. 
 
 APPENDAGES OF THE ALIMENTARY CANAL. 
 The Liver and its Excretory Apparatus. — The Pancreas. — The Spleen. 
 The appendages of the sub-diaphragmatic portion of the alimentary canal are the liver 
 and pancreas, two glandular organs which pour their secretions into the duodenum, and 
 the spleen, which may be regarded as an appendage of the liver. 
 
 * Haller, who, in this and many other passages, seems to have foreseen the law of unity of organization, 
 says, " Eadem primordialis hominis fere fabrica est quae quadrupedum." — (Lib. xxiv., D. 116.) 
 
. THE LIVER. 
 
 •»i>j'> -A ■ ■ . . The Livee. 
 
 The liver {I I', figs. 155, 161) is a glandular organ, intended for the secretion of bile. 
 Moreover, it is to this organ that the blood of the abdominal venous system is carried in 
 the adult, and that of two systems of veins in the foetus. 
 
 It is situated near the duodenum, i. e., the portion of the intestinal canal into which the 
 bile is poured ; it occupies the whole of the right hjT)ochondrium, advances into the epi- 
 gastrium, and even slightly into the left hypochondrium. It is protected by the seven or 
 eight lower ribs on the right side, which defend it from external violence ; and it is separ- 
 ated from the thoracic organs by the diaphragm. It is supported by folds of the peri- 
 toneum connecting it with the diaphragm, and regarded as suspensory ligaments ; by 
 the stomach and intestines, which form a sort of elastic cushion for it ; and by the vena 
 cava, which is intimately adherent to it. These me^ns of support and attachment allow 
 of slight movements to and fro, and even of certain changes of position, not amounting 
 to displacement. Thus, it is depressed during inspiration, and projects a little below the 
 edges of the costdi cartilages ; it is raised during expiration ; it sinks slightly downward 
 during the erect posture, and backward, or in the direction in which its own weight 
 would drag it, according to the way in which the body lies during the horizontal posi- 
 tion ; it is pushed upward by tumours in the abdomen, and dovraward by effusions in the 
 chest. The disturbed sleep to which many individuals are subject when lying upon the 
 left side, is attributed to the pressure of the liver upon the stomach ; and to the dragging 
 of the liver upon the diaphragm has been eiscribed the sensation of hunger, as well as 
 the relief of that feeling produced by tying something tight around the abdomen. These 
 notions are, however, purely hypothetical ; and generally, in solving such questions, the 
 exact state of fulness of the abdomen, and of the mutual action and reaction of the ab- 
 dominal parietes and viscera, has not been sufficiently taken into account. True dis- 
 Dlacements of the liver are very rare, and hepatocele (hernia of the liver) is the result of 
 an imperfect development of the walls of the abdomen. 
 
 Size. — The liver is the largest and heaviest of all the organs of the body ; and, indeed, 
 in the human subject, it exceeds in weight and in size all the other glands together. It 
 is not true, as the ancients declared, that the liver is larger in man than in any other 
 animal. But the opinion maintained by many naturalists, that there is, in the animal 
 series, an inverse ratio between the size of the liver and the development of the respira- 
 tory organs, so that this organ is much larger in reptiles and fishes, whose respiration is 
 slight, than in birds and mammalia, which respire vigorously, is not altogether devoid of 
 loundation. 
 
 The liver weighs from three to four pounds, thus forming one thirty-sixth of the whole 
 weight of the body according to Bartholin, and one twenty-fifth according to others. Its 
 longest diameter, the transverse, is from ten to twelve inches ; its antero-posterior di- 
 ameter is from six to seven inches ; and its vertical diameter in the thickest part, from 
 four to five. These dimensions are extremely variable, but are always inversely pro- 
 portional to each other. In a great many livers the transverse diameter is the shorter, 
 and the vertical the longer. 
 
 Few organs present a greater variation in size and form in different individuals than 
 the liver. I am certain that the relative proportion between different livers may be as 
 much as one to three, in the absence of all disease. It is pretty generally believed that 
 a large liver occasions such modifications in the whole system as will give rise to a par- 
 ticular temperament. But it may be doubted whether there is any proof that the bilious 
 and melancholic temperaments are specially accompanied by a large liver, or that hypo- 
 chondriasis in particular is the result of a predominance of that organ.* AnatomicEil 
 evidence affords but little support to such ideas, which are rather the result of precon- 
 ceived notions respecting the functions of the liver and the influence of the bile, than the 
 fruit of positive observations. 
 
 It varies much in size according to the state of its circulation ; when its vessels, and 
 especially the ramifications of the vena portae, are empty, the tissue of the liver shrinks, 
 and its surface becomes, as it were, wrinkled. When, on the other hand, the hepatic 
 vessels are injected, the organ is in a state of turgescence. I have often been struck 
 with the increase in the size of the liver produced by an injection pushed forcibly and 
 continuously into the vena portffi. 
 
 The size of the liver, as influenced by age and disease, deserves particular attention. 
 I shall point out the influence of age under the head of development. We shall then 
 see that the liver is largest during intra-uterine life, and that it is proportionally larger 
 at periods nearer to that of conception : hence it arises that the greatest relative size 
 of the liver is coincident with the least amount of biliary secretion ; and we may there- 
 fore conclude that this organ has some other use besides that of secreting bile. 
 
 When diseased, the liver has been found to weigh from thirty to forty pounds ; but 
 the enormous size in these cases is almost invariably owing to the development of acci- 
 
 * Hippocrates sometimes gave the name of hypochondria to the liver, and hence, no doubt, the term hypo- 
 chondriac. 
 
 Ccc 
 
386 SPLANCHNOLOGY. 
 
 dental tissues. Some cases, however, have been recorded of simple hypertrophe of the 
 liver without any organic disease, in which the size acquired was prodigious. In oppo- 
 sition to this, we must notice the state of atrophy* in which the liver is shrivelled, and 
 not more than a third, fourth, or even a sixth of the natural size. In one subject, in 
 which the umbihcal vein remained pervious, and the sub-cutaneous abdominal veins were 
 dilated and varicose, the liver weighed only about half a pound. 
 The specific gravity of the liver is, to that of water, as fifteen to ten 
 Figure. — The liver is a single and asymmetrictd organ, of such an irregular form as to 
 defy description. We shall compare it, with Glisson, to a segment of an ovoid, cut ob- 
 liquely lengthwise, thick at its right extremity, and progressively diminishing towards 
 the left, which terminates in a tongue. Its shape is represented by the sort of mould 
 formed by the right half of the diaphragm, and bounded below by an oblique plane di- 
 rected upward and to the left side {fig. 161). 
 
 No organ is more exactly moulded upon the surrounding parts, nor undergoes changes 
 in form with greater impunity, either from external pressure or from that exercised upon 
 it by other viscera ; it may even be said to be, as it were, ductile or malleable under the 
 influence of a slowly-exerted pressure. The injurious effects of very tight lacing are 
 chiefly experienced by the liver. A circular constriction and a fibrous thickening of this 
 organ opposite the base of the thorax sometimes afford evidence of this compression ; 
 its transverse and antero-posterior diameters become diminished, and its vertical diam- 
 eter is increased ; it projects more or less below the base of the thorax, descends as low 
 down as the right iliac fossa, and may even touch the brim of the pelvis without any 
 structural lesion. In these cases, its upper surface becomes anterior, and its lower sur- 
 face posterior. 
 
 There are but few female subjects without some deformity of the liver, and, therefore, 
 the type of the organ must be sought for in the male.t No practical conclusions, then, 
 can be derived from the shape of the liver ; and I am almost inclined to agree with Ve- 
 salius, in saying that it has no determinate form, but accommodates itself to the sur- 
 rounding parts. In a few rare exceptions, we find the human liver divided into lobules 
 by deep fissures, as it is in a great number of animals. The errors which have for a 
 long time existed upon this subject, even since the time of Vesalius, arise from a blind 
 respect for the assertions of older anatomists, who, having dissected few human sub- 
 jects, were accustomed to confound, in their descriptions, the structure found in animals 
 with that observed in man. ^ 
 
 The liver presents for consideration a superior or convex surface, an inferior or plane 
 surface, an anterior and a posterior border, a base, and a summit. 
 
 The superior surface (pars gibba) is convex and smooth, and in contact with the dia- 
 phragm, which is moulded exactly upon it : this convexity is not regular, but much 
 greater on the right than on the left side, where the surface is almost flat {fig. 161). 
 This surface is divided into two unequal parts {I I') by a falciform fold of peritoneum (1 
 to 2), called the falciform or suspensory ligament of the liver, which seems to be principal- 
 ly intended to protect the umbilical vein, and which is never put upon the stretch during 
 the natural state of fulness of the abdomen. One or more fissures are not unfrequently 
 found running from before backward upon the upper surface of the liver ; and I am sure 
 that these fissures, in explanation of which Glisson and Fernel have advanced some 
 very singular opinions, are due, at least in some cases, to the pressure of projecting folds 
 of the diaphragm. The falciform ligament forms the line of separation between the 
 right {I') and the left (/) lobes, a purely nominal distinction, which results from the old 
 habit of admitting several lobes in the liver, and is retained here only for the sake of 
 conformity to custom. The portion of the liver situated to the left of the suspensory 
 ligament is always smaller than that upon the right. 
 
 The convex surface of the liver is bounded behind by the reflection of the peritoneum 
 upon it from the diaphragm. It is separated by the diaphragm from the heait, the ribs, 
 and the base of the right lung. Its relations with the base of the right lung are very ex- 
 tensive : the base of the lung and the convexity of the liver are exactly fitted to each 
 other ; this may be shown by making a vertical section from before backward, upon the 
 right side of the trunk, when the liver will be seen to be received, as it were, into a 
 deep excavation in the base of the lung. This relation explains why abscesses and 
 cysts of the liver may burst into the lung, and why abscesses of the lung point towards 
 the liver ; why the liver may increase in size in the direction of the thorax, and push up 
 the lung as far as the third or even the second rib ; and why effusions into the pleura 
 may force the liver downward in the abdomen ; and also why peritonitis, confined to the 
 region of the liver, is sometimes mistaken for pleurisy at the base of the thorax. The 
 relations of the liver with the seven or eight inferior ribs account for the impressions 
 which are often seen upon its surface ; and also explain the facts, that violent blows 
 upon the ribs may bruise this viscus ; that pointed instruments thrust into the intercos- 
 
 * We cannot admit the proposition of Soemmering, " Quo sanior homo, eo minus ejus hepar est." 
 + Soemmering, without giving any reason, says, " In sexH masculo magit, minus in femineo coatis istit ter. 
 . turn latet."—(Corpor. Hum. Fabric, t. vi., p. 163.) 
 
 m 
 
THE LIVER. 
 
 ^ spaces on the right side may wound it ; and that abscesses of the liver point and 
 open between the ribs. 
 
 The relations of the convex surface of the liver Avith the abdominal parietes, which 
 are so extensive in the new-bom infant, and stiU more so in the foetus, are generally 
 confined in the adult to a variable extent of the epigastrium, and to a small space below 
 the edges of the ribs on the right side {fig. 155). In certain conformations of the liver 
 (almost always acquired), and in such diseases as are attended with an increased size 
 of the organ, these relations become much more extended; and, even in the absence of 
 any disease, the liver is not unfrequently found to extend into the neighbourhood of the 
 umbihcus, or even into the right iliac region. In the erect posture, the liver has a ten- 
 dency to project below the ribs ; and, therefore, the sitting posture, with the upper part 
 of the body inclining forward, and resting upon some object, is the most favourable one 
 for exploring this organ.* It is by no means rare to meet with accidental adhesions 
 between the liver and the diaphragm, consisting either of cellular filaments in the form 
 of bands, or of cellular tissue of a greater or less density. 
 
 The inferior or plane surface {pars sima, 1 1, fig. 154 and fig. 164). This is much more 
 complfeated than the upper surface, and upon it the hepatic vessels enter and make their 
 exit from the liver. Certain eminences and depressions, or fissures of variable depth, 
 are met with here, which have led to the division of the liver into several lobes ; but 
 that kind of division, which in animals appears to enable the organ to adapt itself to the 
 form of the viscera of the abdomen, and has probably some relation with the conforma- 
 tion of the heart, cannot be said to exist in man.t This lower surface is directed down- 
 ward and backward, and sometimes directly backward : it presents for our consideration, 
 in the first place, an antero-posterior fissure, or fissure of the umbilical vein, called also the 
 
 Fig. 16i. 
 
 longitudinal or horizontal fissure 
 (uh,fig. 164), which extends from 
 the anterior to the posterior bor- 
 der of the liver, and is divided by 
 the transverse fissure {dp), meet- 
 ing it at a right angle, into two 
 halves, one anterior, the other 
 posterior. The anterior half lodg- 
 es the umbilical vein in the foe- 
 tus,t or the fibrous cord {u), to 
 which it is reduced in the adult : 
 the posterior half lodges the duc- 
 tus venosus in the fcetus, or the 
 fibrous band {v), by which it is re- 
 placed after birth. The anterior 
 half of the longitudinal fissure is 
 much deeper than the posterior, 
 and is often converted into a com- 
 plete canal by a sort of bridge 
 formed by a prolongation of the substance of the liver : when incomplete, this bridge is 
 always situated near the transverse fissure : it often consists of a band of fibrous tissue. 
 Even when quite complete, it invariably presents a notch near the anterior border of the 
 liver. ^ The posterior half of the longitudinal fissure inclines more or less obliquely to 
 the left of the lobulus Spigelii (3), gives attachment, like the transverse fissure, to the gas- 
 tro-hepatic omentum, and communicates with the fissure for the vena cava superior (c), 
 behind the lobulus Spigelii. 
 
 The existence of this fissure has been the chief cause of the division of the liver into 
 the right or great lobe (1), and the left lobe (2), also termed the middle-sized lobe by those 
 anatomists who admit as a third lobe the small lobe, the lobule or the lobulus Spigelii (3). 
 This division of the liver into two lobes is also marked on the upper surface, as we have 
 already seen, by the suspensory ligament. Of these lobes, the right is much larger than 
 the left ; the former occupies the right hypochondrium, the latter the epigastrium and 
 left hypochondrium {fig. 161). The proportion between the right and the left lobe can- 
 not be precisely determined. The left lobe is sometimes reduced to a thin tongue, while, 
 at other times, it is almost half the size of the right lobe. Generally, the relative pro- 
 portion between them is as six to one. This, however, is of but little consequence ; for 
 as the distinction between the two lobes is quite imaginary, the substance of the left 
 
 * In an old woman, whose liver was deformed but healthy, and projected below the ribs, I was able to diag- 
 nosticate, by mediate percussion, the existence of a knuckle of intestine between the liver and the parietei 
 of the abdomen. Very lately I found a large loop of the transverse arch of the colon between the right lobe 
 and the abdominal parietes, and a loop of the small intestine between the left lobe and those parietes. 
 
 t The ancients admitted four lobes in the liver, which they distinguished by the singular names of mensa, 
 porta, gladius, and unguis. 
 
 t [The term umbilictil fissure is often restricted to this part of the longitudinal fissure ; the posterior half it 
 then called the fossa of the ductus venosus.] 
 
 [This bridge was purposely divided in the liver from which Jig. 164 was drawn.] 
 
SPLANCHNOLOGY. 
 
 may, without any inconvenience, be included in the right, and vice versa. TKe transverie 
 fissure, or fissure of the vena ■porta {d p), is the true hilus of the liver, for through it the 
 hepatic vessels enter and pass out. It is a very broad, transverse fissure, from fifteen 
 to eighteen lines in length, occupying ahnost the middle of the lower surface of the liver, 
 a little nearer to the posterior than to the anterior border, and to the left than to the right 
 extremity. It is bounded on the left by the longitudinal fissure, with which it commu- 
 nicates ; to the right of the gall-bladder {g), it is prolonged obliquely forward by a deep 
 and narrow cleft. In the transverse fissure we find the vena portae, or the sinus (p) of 
 the vena portae, the hepatic artery (a), the roots of the hepatic duct (d), a great number 
 of lymphatic vessels and nerves, and a considerable quantity of cellular tissue. The 
 gastro-hepatic omentum is given off from this fissure. The transverse fissure is situa- 
 ted between two eminences, called by the ancients the pillars of the gate {portal eminen- 
 ces). All the peculiarities of the inferior surface of the liver may be referred to these 
 two fissures. 
 
 Thus, to the left of the longitudinal fissure we observe the inferior surface of the left 
 lobe, slightly concave behind, where it is applied to the lobulus Spigelii, from which it is 
 separated by the gastro-hepatic omentum ; concave in front, so as to be adapted to the 
 convexity of the stomach, upon which it is prolonged to a greater or less extent. This 
 relation of the liver with the stomach is of the utmost importance. Thus, when the 
 stomach is distended, it pushes the liver upward and backward in such a manner that 
 its lower surface is directed somewhat forward. In cases of chronic ulceration of the 
 stomach, the tissue of the liver is not unfrequently found supplying the place of the de- 
 stroyed coats of the stomach, and this to a considerable extent. The lower surface of 
 the left lobe is often in relation with the spleen, which it occasionally covers like a helmet. 
 
 To the right of the longitudinal fissure, and in front of the transverse fissure, we find, 
 upon the lower surface o'f the right lobe, the fossa for the gall-bladder, which is more or 
 less deep, oblong, and directed from before backward, upward, and to the left side, like 
 the gall-bladder (g) itself, for the reception of which it is intended. This fossa is not al- 
 ways prolonged as far as the anterior border of the liver. Between the fossa of the gall- 
 bladder and the longitudinal fissure is a square surface, the lobulus quadratus, anterior 
 portal eminence, or anterior lobule (4). This surface sometimes terminates behind in a dis- 
 tinct rounded prominence, which justifies the name of eminence applied to it ; at other 
 times, on the contrary, this portion of the liver is flattened. 
 
 Behind the transverse fissure we find the posterior portal eminence, or small lobe (pos- 
 terior lobule or lobule), also called the lobulus Spigelii (3), from the name of the anatomist 
 to whom its discovery has been attributed, although it was described, and even figured 
 before his time by Vesalius, Sylvius, and Eustachius. It varies much, both in size and 
 shape, and is situated between the transverse fissure and the posterior border of the liver, 
 and between the fissure of the ductus venosus (») on the left, and the fissure of the vena 
 cava inferior (c) on the right. It is situated to the right of the oesophageal orifice of the 
 stomach, opposite its lesser curvature, by which it is embraced ; its form is that of a 
 flattened semilunar tongue, convex upon its lower and free surface, which corresponds 
 to the upper border of the pancreas, and has a projection in the centre, surrounded by 
 an arterial circle, formed by the coronary artery of the stomach with the splenic and 
 hepatic arteries. This projection (above 3) is called by Haller major colliculus in magna 
 papilla similitudinem; and by Winslovv, r eminence triangulaire. From its posterior ex- 
 tremity a prolongation is given off opposite the posterior border of the liver, which con- 
 verts the fissure for the vena cava inferior into a canal that is sometimes complete.* A 
 prolongation or ridge (5) {the right prolongaiion of the lobule) passes from its anterior ex- 
 tremity to the right of the transverse fissure, and, proceeding obliquely forward, separ- 
 ates the renal (r) from the colic (o) depression. This prolongation was minutely descri- 
 bed by the older anatomists, and has been termed by Haller the colliculus caudatus.j At 
 its junction with the lobule, this prolongation is marked in front by a groove (the groove 
 of the vena porta), sufficiently deep to lodge the vena portae (p) and the hepatic artery (a) ; 
 and it is still more deeply excavated behind for the vena cava inferior (c) {the groove of 
 the vena cava inferior). Sometimes the right margin of the first-mentioned groove has a 
 papilla similar to that of the lobulus Spigelii ; and in this case it might be Sciid that there 
 are two lobes of Spigelius ; opposite this groove, the vena portae is separated from the 
 vena cava only by a very thin lamina. 
 
 The lobulus Spigelii presents much variety in its size ; but not such as to enable it to 
 be felt through the abdominal parietes, unless the enlargement is the consequence of 
 disease. Physicians who pretend to recognis.e by the touch obstruction or adhesion of 
 the lobulus Spigelii,t are certainly not anatomists. 
 
 To the right of the longitudinal fissure, the lower surface of the liver presents, behind, 
 
 * [This prolong-ation did not exist in the liver represented in fig. 1G4.] 
 
 + [Now termed the lobulus caudatus.] 
 
 ; Meckel and others consider that there is a right antero-posterior, or longitudinal fissure, formed by the 
 tossa for the gall-bladder and the groove of the vena cava inferior ; the latter groove being partly hollowed 
 t ut af the loCulus Spigelii, and partly out of the continguous portion of the right lobe, and then prolonged 
 upon the lower surface of the liver 
 
THE LIVER. 
 
 au excavation of variable depth and extent in different subjects ; this is the renal im- 
 pression (r) : it corresponds to the kidney, upon which it is exactly moulded, and with 
 which it is loosely united, and also, though more loosely, with the supra-renal capsule. 
 Sometimes the impression for the capsule is distinct from that for the kidney. It may 
 be conceived that this impression must vary according as the liver corresponds to the 
 uj^er third, to the upper half, or to the whole of the right kidney. This impression is 
 always directed backward. 
 
 In front of the renal impression is a slight one, termed the colic depression (o), which 
 corresponds with the angle formed by the ascending and transverse colon with part of 
 the transverse colon itself, and sometimes, also, with the first portion of the duodenum. 
 
 Behind is the groove for the vena cava inferior (c), which advances slightly upon the 
 lower surface of the liver, on the inner side of the renal and capsular impression. 
 
 The accidental fissures sometimes observed upon the lower surface of the liver are 
 traces of the divisions which exist in a great number of mammalia. 
 
 To recapitulate the numerous objects seen upon the lower surface of the liver, we find 
 as follows : the antero-posterior or longitudinal fissure, intersected at right angles by the 
 transverse fissure ; on the left of the antero-posterior fissure is the lower surface of the 
 left lobe, presenting the depression for the lobulus Spigelii, the gastric impression, and 
 sometimes the splenic ; on the right and in front of the transverse fissure, are the fossa 
 of the gall-bladder, and the anterior portal eminence, or lobulus quadratus ; behind the 
 transverse fissure is the posterior portal eminence, or lobulus Spigelii, with its right 
 prolongation or lobulus caudatus, and the groove for the vena portae ; and still more to 
 the right are the renal and colic impressions, and the groove for the inferior vena cava. 
 
 The Circumference of the Liver. — The anterior border of the liver presents a very thin, 
 and, as it were, sharp edge, which is directed obliquely upward and to the *ft side, cor- 
 responding to the base of the thorax on the right side, and projecting below it, opposite 
 the sub-sternal notch (Jig. 155). Upon this edge there is invariably found a deep notch 
 (below 2, Jig. 161) for the umbilical vein ; and more to the right another notch, which is 
 often larger than the preceding, and corresponds to the base (g) of the gall-bladder. 
 Sometimes there is merely a trace of this notch, and sometimes it is altogether wanting. 
 In some subjects there is only one great notch, common to the gall-bladder and the um- 
 bilical vein, and the borders of it are sinuous, or cut into small notches. It is almost 
 always possible, when the parietes of the abdomen are relaxed, to insinuate the fingers 
 between the ribs and the liver. 
 
 The posterior border of the liver is very thick in all that part which corresponds to the 
 right side, and becomes gradually thinner as it approaches the left extremity. This 
 border, which is short, rounded, and curved, so as to fit the convexity of the vertebral 
 column, adheres intimately to the diaphragm by rather dense cellular tissue. The peri- 
 toneum is reflected, both above and below this border, from the diaphragm to the liver, 
 to form what is called the coronary ligament. The cellular interved between these two 
 layers of peritoneum is of irregular form, and taries in size. This border is divided into 
 two parts by a deep notch, which forms two thirds or three fourths of a canal for the re- 
 ception of the inferior vena cava {c,Jig. 164). This notch is converted into a complete 
 canal, sometimes by a sort of fibrous bridge, and sometimes by a prolongation fi-om the 
 posterior extremity of the lobulus Spigelii. In order to comprehend the arrangement of 
 the liver opposite this notch for the vena cava, that vein should be slit open, and we then 
 see at the bottom of a deep notch a large cavity, into which all the hepatic veins (Ji h) 
 open. We observe, also, that the antero-posterior fissure is continuous with the fissure 
 of the vena cava, behind the lobulus Spigelii. This lobule, viewed from behind, appears 
 like a tongue detached from the rest of the liver, by circumscribing fissures and grooves. 
 
 On the right side, the liver terminates in a thick, smooth extremity, forming the base 
 of the pyramid, to which this organ has been compared. A triangular fold of peritone- 
 um, caUed the right triangular ligament (/), is stretched from the middle of this thick ex- 
 tremity to the diaphragm. 
 
 On the left side, the liver terminates in an angular or obtuse tongue, more or less elon 
 gated, and sometimes reaching as far as the spleen, to which I have seen it adherent 
 This prolongation, which is attached to the diaphragm byatriangular fold of peritoneum, 
 called the left triangular ligament (3, fig. 161 ; I, fig. 164), is slightly notched behind for 
 the lower end of the oesophagus, which is bordered by it upon the left side. In one sub- 
 ject I saw this tongue completely separated from the rest of the liver, with the excep- 
 tion of a veiscular pedicle about four lines in length. This peculiarity was probably ow- 
 ing to traction exercised by the spleen, to which the prolongation from the Uver was in- 
 timately adherent. 
 
 Colour. — The liver is of a reddish-brown colour, the depth of which varies in different 
 individuals. Its surface, and also sections of it, resemble in appearance a granite com- 
 posed of two kinds of grains, the one deep brown, the other yellowish ; and hence has 
 arisen the distinction between the two substances of the Uver. In no tissue in the body 
 is there greater variety in colour than in that of the liver. Independently of the differ- 
 ent shades, which it is imoossible to describe, the liver is sometimes of a yellowish or 
 
390 SPLANCHNOLOGY. 
 
 canary-yellow, or a chamois-yellow (hence the name cirrhosis given to a particular dis- 
 .ease of the liver) ; or it may be of a more or less deep olive-green hue, or of a slate 
 colour. These differences in colour, which have not, perhaps, been sufficiently investi- 
 gated, are connected with more or less decided alterations of texture. The chamois- 
 yellow colour almost always indicates the existence of fatty degeneration. 
 
 Fragility. — ^The fragility of the liver is one of the most important particulars in its de- 
 scription. It is compact and fragile, and cannot, therefore, be forcibly compressed with- 
 out suffering laceration ; hence the danger of contusions in the region of the liver, and 
 the rules laid down by accoucheurs for avoiding all compression of the abdomen of the 
 feet us during the manipulations required in protracted labours. The fragility and the 
 weight of the liver explain the occurrence of injuries of that organ by contre-coup, after 
 falls from an elevated height. In fatty degeneration of this organ, the liver retains the 
 impression of the finger, and its fragility is in a great measure lost. Olive-green and 
 slate-coloured livers are dense, their molecules are much more closely united, and they 
 are lacerated with difficulty. 
 
 Texture. — Before the admirable works of Glisson and Malpighi, anatomists were in the 
 habit of saying, with Erasistratus, that the liver, like all other organs of a complicated 
 structure, was a parenchyma ; a vague term, intended to imply the effusion of a particular 
 juice around a series of vessels. Malpighi showed, in opposition to the assertion of 
 Warthen, that the liver is a conglomerate gland : he examined the glandular granules 
 (the lobules of Kiernan), which Ruysch subsequently, by means of his beautiful injec- 
 tions, appeared to convert into vessels. Anatomists are still divided between the opin- 
 ions of these two eminent observers concerning the intimate structure of the liver, as 
 well as of all other glands, some believing it to be granular, others that it is vascular. 
 We have to' consider the coverings, and then the proper tissue of the liver. 
 
 The Coverings of the Liver. — These are two in number, viz., a peritoneal coat, and a 
 proper fibrous membrane. 
 
 The peritoneal coat forms an almost complete covering for the liver ; the posterior bor- 
 der, the transverse fissure, the groove for the vena cava, and the fossa for the gall-blad- 
 der, are the only parts that are destitute of this coat. The peritoneum, from being re- 
 flected upon the liver from the diaphragm, constitutes the several folds called the falci- 
 form, coronary, and triangular ligaments, of which we have already spoken. By means 
 of this membrane, which is always moist, the liver is enabled to glide upon the adjacent 
 parts without friction. We frequently find cellular adhesions between the liver and sur- 
 rounding structures, which do not positively impair its functions. The peritoneal coat 
 adheres intimately to the proper membrane. 
 
 The proper or fibrous membrane is very well seen over such portions of the liver as are not 
 covered by the peritoneum, and from these points it can be easily traced over the whole 
 of the remainder of the organ. It constitutes the immediate investment of the liver ; its 
 outer surface is adherent to the peritoneal coat, and its inner surface is connected with 
 the tissue of the liver by means of fibrous prolongations interposed between the granules 
 (lobules), affording to each a distinct covering. 
 
 It passes into and lines the transverse fissure, and is prolonged around the correspond- 
 ing divisions of the vena portae, the hepatic artery, and the biUary ducts, so as to form 
 cylindrical sheaths for those groups of vessels, and for all their farther divisions and sub- 
 divisions. These sheaths constitute the capsule of Glisson, which we must therefore re- 
 gard as a dependance of the proper fibrous coat. The internal surface of these sheaths 
 is united to the vessels only by a very loose cellular tissue. Their external surface ad- 
 heres intimately to the tissue of the liver by fibrous prolongations, which interlace in 
 every direction, and form distinct coverings for the deep-seated granules, analogous to 
 those which we have already stated are produced from the proper coat. The liver, 
 therefore, is traversed in all directions by very delicate fibro-cellular prolongations, form- 
 ing a vast network, in which the granules are contained. This proper coat, moreover, 
 is fibrous,* not muscular, as Glisson believed. 
 
 It may be said, with truth, to constitute the skeleton or framework of the liver, for it 
 affords a general covering for the organ ; it is prolonged around the vena portae, the he- 
 patic artery, and the biliary ducts, and it furnishes a fibrous or cellular covering for each 
 of the granules composing the proper tissue of the liver. The fibrous cells thus fonned 
 become very distinct in certain cases of hepatic disease. In fact, this fibrous tissue not 
 unfrequently becomes so much hypertrophied, that some of the glandular granules are 
 compressed and atrophied ; and then larger or smaller portions of the liver appear to be 
 converted into a reticulated fibrous tissue. The arrangement of the fibrous tissue is also 
 very manifest in cases of softening of the granules, which may then be easily scraped 
 out of their cells, and the surface of the section thus treated presents the appearance of 
 the cells in a honeycomb. 
 
 The Proper Tissue of the Liver. — The first thing that strikes an observer in examining 
 the structure of the liver, is the smoothness of its external surface, which does not pre- 
 sent any of the lobulated appearance of most other glands. If we attentively examine 
 
 * [It is composed of dense cellular or fibro-cellular tissue : for its use, see note, p. 393.1 
 
THE LIVER. 391 
 
 this surface, either before or after the removal of its coverings, we find that it is most 
 distinctly composed of granules (lobules, Kieman) : the same is also rendered evident by 
 making sections of the organ, or by tearing it : the granular arrangement has, it is true, 
 been supposed to be the result of laceration. 
 
 From the mottled appearance of the liver (like granite), already noticed, anatomists 
 have admitted the existence of two substances, or, rather, two kinds of granules in this 
 organ, viz., reddish brown and yellow granules. This distinction was first made by Fer- 
 rein (Hist. Acad, des Sciences, 1735) ; it is now generally recognised, and has even served 
 as the basis of several more or less ingenious explanations. This anatomist called the 
 brown substance medullary, and the yellow cortical, names evidently derived from a rude 
 analogy between them and the medullary and cortical substances of the brain. Others 
 have reversed the meaning of these two words ; but that is of little consequence. 
 
 " These two substances," says Meckel, " are not arranged as in the brain, one exter- 
 nal and the other internal ; but alternately throughout the whole liver, the yellow sub- 
 stance forming the mass of the organ, and the brown substance occupying the intervals." 
 This distinction into two substances does not appear to me to be well founded. The 
 error has arisen from assuming as constant the existence of two colours, which, how- 
 ever, are far from being distinguishable in all subjects. The two colours, yellow and 
 brown, when they do exist, do not belong to two distinct granules, but rather to the same 
 granule, which is yellow in the centre, where the bile is found, and reddish brown at the 
 circumference, where the blood is collected.* 
 
 The granules of the human liver are so small, that, excepting when they become con- 
 siderably enlarged, it is not well adapted for examination. The liver of the pig, in which 
 the granules are naturally very large, appears to me the best suited for this purpose. I 
 have been accustomed to divide the liver in different directions, to slit up and remove 
 the veins which have been cut across, and afterward to examine the granules in the 
 semi-canals {g g,fig. 165 ; c c,fig. 166) which they then form. The granules (/ 1 1) may 
 thus be separated with the greatest facility ; they are small, ovoid, elliptical, or, rather, 
 polyhedral bodies, having five or six surfaces, and shaped so as to be moulded upon the 
 surface of the adjacent granules, without leaving any interval. It is evident, therefore, 
 that there is only one order of granules ; that these granules are not arranged in lobules, 
 as stated by Malpighi,+ but are merely in juxtaposition ; and that each has its proper cap- 
 sule, formed by prolongations of the fibrous coat. And as these granules can be isolated, 
 and detached from the capsules in which they are merely lodged, without adhering to 
 them, except at the points by which they receive and emit their vessels, it follows that 
 they are independent of each other, and that the most complete alteration of one or more 
 of them may take place, without the adjacent or intermediate granules being in any 
 way affected, or, at least, that such alteration would not be propagated by continuity of 
 tissue. 
 
 The size of the granules varies much in different individuals, and is quite independent 
 of the size of the liver itself Physicians who have paid much attention to pathological 
 anatomy have often mentioned their increased development, by the name of hepar aci- 
 nosum. This disease is characterized by the simultaneous occurrence of atrophy of the 
 entire organ, which is reduced to one half or one third its original size, and of hyper- 
 trophy of the granules themselves. In what is called cirrhosis, the greater number of the 
 granules are atrophied, t 
 
 The investigation of the structure of the liver is, then, reduced to the determination of 
 the arrangement of the granules with respect to each other, of the mode in which the 
 vessels are arranged, and of the structure of each granule. 
 
 1. The arrangement of the granules, with regard to each other, is revealed by the fol- 
 lowing fact : In the disease of the liver called ramollisement {Diet, de Med. et Chir. Pratiq., 
 art. Maladies du Foie), in which that organ is reduced to a sort of pulp, as soon as the 
 investing membranes are torn, the tissue of the liver escapes like a brownish-yellow 
 pulp, which, as it is not fetid, cannot be supposed to be the result of gangrene. If this 
 pulp be placed in water, myriads of small and very distinct yellow granules will be seen, 
 resembling small raisin stones, and appended to the ramifications of the different kinds 
 of vessels by vascular pedicles. 
 
 This fact, which I have several times observed, is confirmed by the observations of 
 Harvey, who, in his work upon the generation of animals, says, that the tissue of the 
 liver is formed along the umbilical vessels like a grape on its footstalk, a bud on the end 
 of a twig, or an ear of corn springing from its stalk ; and also by reference to compara- 
 
 * See note, p. 395. 
 
 t [This statement illustrates the confusion that has prevailed from the terms lobule and acinus having' been 
 employed by anatomical writers in different senses to those attached to them by Malpighi ; the lobule of Mal- 
 pighi is, in fact, equivalent to the granule of M. Cruveilhier, and was described by him as consisting of a col- 
 lection of acini {see note, p. 395).] 
 
 t The ingenious explanation which has been given of cirrhosis is, then, destitute of foundation. In cirrhosis, 
 as I have shown in another place, there is neither atrophy of the red substance, nor hypertrophy of the yellow, 
 but rather atrophy of the greater number of granules, with hypertrophy and yellow discoloration of the re- 
 mainder. 
 
392 SPLANCHNOLOGY, 
 
 tive anatomy, for M. Blainville has informed me that, in certain species of animals, the 
 liver is formed by rows of glandular granules attached aJong the vessels.* 
 
 2. The Vessels of the Liver. — The study of the vessels of the liver is one of the most 
 important points in the history of that organ. Besides the arteries and veins correspond- 
 ing to those of other parts of the body, the liver receives also a special system of veins, 
 viz., the system of the vena porta, which is distributed in its interior like an artery. It 
 presents also, in the adult, the remains of a venous system peculiar to the foetus, the sys- 
 tem of the umbilical vein ; and, lastly, it contains canals intended for the conveyance of 
 the bile, named the biliary ducts. 
 
 The special venous system of the liver, or the system of the vena porta, will be described 
 more particularly in another place. I shall only now observe, that the branches of ori- 
 gin of this system commence in all the abdominal organs concerned in the function of 
 digestion ; that the ventral venaportae, resulting from the union of these branches, reaches 
 the transverse fissure of the liver, and divides there into a right and left branch, which 
 constitute the hepatic vena portae {p, fig. 164) ; and that these branches subdivide and 
 spread into all parts of the liver, some forward and others backward, but all following a 
 transverse direction. The capsule of Glisson, as we have seen, is developed around this 
 vein ; so that, in sections of the liver, the branches of the vena portae can always be rec- 
 ognised by these two characters : a transverse direction, and the presence of the capsule. 
 Remmtis of the Umbilical Vein. — We can easily conceive the arrangement of these re- 
 Fig. 164.t mains, if we consider that, in the foetus, the umbilical 
 
 vein (m, fig. 164t), proceeds from the placenta to the 
 longitudinal fissure of the liver ; and at the point where 
 this is intersected by the transverse fissure, divides into 
 two branches, one of which, under the name of the duc- 
 tus venosus (d), passes directly to the vena cava (c), at 
 the point where it traverses the posterior border of the 
 liver ; while the other is continuous with the hepatic 
 vena portae (jf), which, as we have seen, occupies the 
 transverse fissure. The portion common to the umbil- 
 ical and portal veins remains pervious in the adult ; but 
 it then belongs exclusively to the vena portae. The ductus venosus then becomes a mere 
 fibrous cord {v, fig. 164t), as well as the trunk of the umbilical vein itself (m). It is not 
 rare to find the trunk of the umbilical vein persistent in the adult, from an abnormal com- 
 munication between it and the veins of the abdominal parietes. (See Anat. Path, avec 
 planches, liv. xvii., pi. 6.) No example has been recorded of a persistent ductus venosus. 
 Arteries. — The hepatic artery is a branch of the coeliac axis {t,fig. 154), which also 
 furnishes branches to the spleen and the stomach ; and although a difference in the ori- 
 gin of an artery dose not occasion any difference in the blood within it, yet this com- 
 munity of origin is not the less remarkable, for it seems to denote a community, a coinci- 
 dence, or a connexion of function. Moreover, as the nervous plexuses are supported 
 upon the arteries, it follows that the nerves of the spleen, stomach, and liver, are de- 
 rived from a common plexus, the cceMac. We frequently find a second hepatic artery 
 arising from the superior mesenteric. 
 
 I must not omit to mention the smaUness of the hepatic artery in comparison with the 
 size and mass of the liver. In this respect few organs present so great a disproportion : 
 compare, for example, the kidney and the renal artery, look at the muscles, and I may 
 almost say at the bones. The small caliber of the hepatic artery enables us to determine 
 d priori, that it cannot serve both for the nutrition of the organ and for the secretion of 
 the bile. Lastly, it exactly follows the r2unifications of the vena portae and the biliary 
 ducts, and the capsule of Glisson is common to it and to those two sets of vessels. 
 
 The Hepatic Veins. — The hepatic veins, the efferent vessels of the liver, are not pro 
 portion al to the size of the hepatic artery, but to that of the vena portae. Proceeding 
 from all points of the liver, and converging towards the fissure of the vena cava, the 
 hepatic veins {h h',fig. 164) empty themselves into that vein (c), especially near the pos- 
 terior border of the liver. It follows, therefore, that the direction of the hepatic veins 
 and of their divisions is from before backward, while that of the divisions of the vena 
 portae is transverse. t This direction, and the absence of the capsule of Glisson, on ac- 
 
 * Arrangement of the ioiuZe^.— [According to M. Kieman, from whose paper in the Phil Trans, for 1833 
 this and the succeeding notes on the structure of the liver are derived, the lobules (g^ranules, Cruveilhier) of 
 the human liver are many sided bodies, flattened on one surface, called the base, and forming- processes in 
 every other direction ; hence, in a longitudinal section they present a foliated, and in a transverse section a 
 polyhedral form. The bases of all the lobules (c c,fig. 166) rest on certain branches of the hepatic vein, call- 
 ed «u4-lobular veins (A h) ; while their other surfaces, surrounded by the capsular investments, are either in 
 contact with those of the adjacent lobules, or appear on the outer surface of the liver, or in the portal canals 
 ^g gifig- '65). which contain the \4ka. portae, hepatic artery, and hep.atic duct, or in those fur the lars^er trunks 
 (h,fig. 166) of the hepatic vein. The intervals between the sides of the lobules are the inter-l(>bular/«s«r««, 
 and the points at which two or more of ihese meet are the inter-lobular spaces. The superficial lobules are 
 imperfect, or more or less flattened on their exposed side.] 
 
 t At least in the principal t'orVs ; for there are a great number of ramifications of the hepatic veins which 
 pass transversely. 
 
THE LIVEE. 
 
 393 
 
 count of which the walls of these veins are directly adherent to the tissue of the liver, 
 so that the veins themselves remain patent, while the sections of the vena portae collapse, 
 are the two characters by which the divisions of the hepatic veins may be distinguished 
 from those of the vena portae, on simply inspecting a section of the liver. Do these 
 anatomical differences between the two kinds of veins produce any difference in the 
 mechanism of the circulation through them ] And is the want of immediate connexion 
 of the divisions of the vena portae to the tissue of the liver intended to permit them to 
 contract so as to propel the blood ] If we consider that the blood of the vena portae pro- 
 ceeds from the trunk towards the branches, as in the arteries, we may conceive the ad- 
 vantages which must result from an anatomical arrangement that would allow these 
 vessels to exert a direct pressure upon the blood. 
 
 Another point of difference between the branches of the hepatic vein and of the vena 
 portae is, that the walls of the former are perforated by a multitude of extremely small 
 openings or pores, which are the orifices of very small veins. 
 
 The Lymphatic Vessels. — The lymphatics of the liver are so numerous that these ves- 
 sels were first discovered in that organ ; indeed, it was for a long time regarded as the 
 origin of the lymphatic system, just as it had been originally considered the origin of the 
 veins. The lymphatics of the liver form a superjicicd and a deej> set. The superficial 
 lymphatics are arranged in an extremely close network under the peritoneal coat. Tlie 
 deep set, which are very large and numerous, pass out of the transverse fissure of the 
 liver, and terminate partly in lymphatic glands situated along the hepatic vessels, and 
 partly in the lumbar glands. They communicate directly and freely with the thoracic 
 duct, so that one of the best methods of injecting this duct consists in throwing the in- 
 jection into the lymphatics of the liver. 
 
 The Nerves. — These are very small, considering the size of the liver. They are deri- 
 ved from two sources, the cerebro-spinal and the ganglionic gystems. The former are 
 branches of the pneumogastric nerves ; the latter constitute the hepatic plexus, which 
 is an offset from the solar plexus. They are interlaced around the hepatic artery : some 
 of these nerves, however, by a special exception, accompany the vena portae. It is gen- 
 eredly admitted that a few filaments of the phrenic nerve are given to the liver. 
 
 The Biliary Ducts. — Wiiatever may be the origin of the biliary ducts, their radicles, 
 however small they may be, are always found in the capsule of Glisson, together with 
 the corresponding branches of the vena portae and hepatic artery. These radicles are 
 united like veins into smaller, and these into larger branches, which, at length, consti- 
 tute the hepatic duct (d,fig. 164). They can be readily distinguished from the other vas- 
 cular canals of the liver by their yellowish colour, by the fluid which they contain, and 
 by the appearance of their parietes.* 
 
 * Vessels. — [The first divisions ef the vena portae, hepatic artery, and hepat- 
 ic duct, are situated in the portal canals, which are tubular passages formed 
 in the tissue of the liver, commencing at the transverse fissure, and branching 
 through the Substance of the organ. The smallest divisions of the portal ca- 
 nals contain one principal branch of each of these vessels (P a d,fig. 165) : 
 from these proceed smaller branches, called vaginal, from their situation with- 
 in the capsule of Glisson. jf 
 
 In the larger canals, the vaginal veins (p" form a plexus in the substance 
 ■p of the capsule, and then give off the tn(er-lobular veins (p p), which pass be- 
 tween the lobules opposite the inter-lobular spaces, ramify in the inter-lobular 
 fissures (p p,fig. 167), and, after freely anastomosing upon the capsular surfa- 
 ces of the lobules, divide into branches, which penetrate the lobules them- 
 selves. In the smaller portal canals, the vaginal venous plexuses are less ap- 
 parent, for many of the inter-lobular veins (i) arise at once from the principal 
 branch of the vena portae : where Fig. 166^ 
 
 this occurs, the capsule of Glis- 
 son is very thin ; and, indeed, the 
 chief use of this structure, in oth- 
 er situations, appears to be to form a web, on which the vessels 
 may ramify, so as to enter the liver at a great number of points, 
 a use analogous to that of the pia mater and periosteum, in refer- 
 ence to the brain and bones. 
 
 The hepatic artery also forms vaginal plexuses in the portal 
 canals, wiiich give off inter-lobular hranches ; from these vessels 
 the proper capsule of the liver, the capsule of Glisson, the cap- 
 sules of the lobules, and the coats of the different vessels, derive 
 their nutrier.'. aT*«ries, which terminate in veins that enter the 
 vena portse. But few arterial branches enter the lobules them- 
 selves. 
 
 The hepatic duct, also, has its vaginal branches, but it is doubt- 
 ful whether they anastomose ; they are formed by the union of 
 the inter-lobular branches (d d,fig. 168), which do appear to anas- 
 tomose, and are derived from the biliary ducts, which pass out at 
 the surface of the lobules. 
 
 The several divisions of the hepatic veins are termed the he- 
 patic venous trunks, the su6-lobular veins, and the infra-lobular 
 veins. The inira-lobular veins (i,fig. 166 ; h,fig. 167), of which , 
 but one, independent of the rest, emerges from the centre of the * 
 
 base of each lobule, open into the sub-lobular veins (A A), through - . •/ ■< r v 
 
 the thin walls of which can be seen the polyhedral bases of the lobules, and the central orifices (t t ) of Ul0 
 
 D n D 
 
394 SPLANCHNOLOGY. 
 
 3. What is the structure of the gramdcs ? In examining a section of the liver of a pig 
 with the simple microscope, I have seen most distinctly that each granule has a porous 
 and spongy appearance, like the pith of the rush or elder, so that the proper tissue of the 
 liver resembles a sort of filter. This appearance was much more distinct in livers which 
 I had injected with walnut oil, either pure or coloured blue. The colouring matter thrown 
 into the vena portae was, as it were, infiltrated into the spongy tissue of the liver. 
 
 If we endeavour to ascertain the structure of the liver by means of injections, we shall 
 see what was observed by Soemmering, that whichever vessel be injected, whether the 
 hepatic artery, the duct, the vena portae, or the hepatic vein (provided only the injection 
 be thin, as, for example, coloured glue, size, or spirits of turpentine, or, better still, a 
 strong aqueous solution of gamboge), there will not be a single granule into which the 
 injection will not have penetrated ; and, moreover, that the liquid throvra into one ves- 
 sel will pass either into one, two, or all three of the others ; and the facility with which 
 this takes place proves that the different orders of vessels communicate with each other 
 directly, and not through the medium of cells or small cavities.* 
 
 In a foetus, or an infant that has died immediately after birth, an injection through the 
 umbilical vein gives similar results. I have never been able to force the liquid into the 
 l)Tnphatic vessels, at least without rupturing the tissue of the liver. Air driven into the 
 vessels penetrates more easily than liquids into the lymphatics, no doubt on account of 
 its greater subtilty. 
 
 It follows, then, that in each granule there is an arterial radicle, a radicle of the vena 
 portae, one of the hepatic vein, and one of the duct, probably some lymphatic vessels, and 
 a nervous filament. The aggregate has been represented by Soemmering as having 
 some resemblance to the arrangement of a Damask rose.f All the different vessels 
 communicate freely with each other.t 
 
 The manner in which these different vessels are arranged in each granule can only 
 be discovered by injecting them simultaneously, or, rather, successively, for it is nearly 
 impossible to inject all the vessels of the liver at the same time. I have accordingly in- 
 jected the vessels in the following order : the vena cava, and, consequently, the hepatic 
 veins, with wax coloured with Prussian blue — a certain quantity of walnut oil, also con- 
 taining Prussian blue, had been previously thrown into the same vein ; the vena portee 
 with a red injection ; the hepatic artery with the same ; and then the hepatic duct with 
 a yellow injection. These injections were made in the liver of a pig, the liver being 
 placed in warm water, and the injections pushed in with a gradually-increasing force. 
 During the injection of the vena cava and vena portae, the wrinkles of the liver disap- 
 peared, and the central depressions of the superficial granules became, on the contrary, 
 slightly prominent. It was therefore evident that each granule was hollow, and that 
 the space had been filled by the injected matter. 
 
 The liver thus injected and submitted to different chemical agents gave the following 
 results : The blue injection, or that which had been thrown into the vena cava, had pen- 
 etrated into the central part of each granule, which is generally called the yellow suh 
 stance of the liver. In the middle of the central part was the yellow injection from the 
 hepatic duct. Around tl\^ blue injection was found that coloured red, which had been 
 forced into the vena port* and the hepatic artery, and which occupied all the so-called 
 red substance of the liver. It follows, therefore, that each granule had a vascular appa- 
 ratus thus arranged : in the centre, a biliary duct ; farther removed from the centre, a 
 vascular circle formed by the ramifications of the hepatic vein ; and external to this 
 another vascular circle, formed by ramifications of the vena portae and hepatic artery. 
 As to the manner in which the vena portae and hepatic artery are arranged in relation to 
 each other, we shall find, if we trace them into the substance of the liver, that the ram- 
 ifications of the hepatic artery correspond exactly to those of the vena portae and biliary 
 duct, which, as we have already said, are all contained in the same sheath ; and that 
 they ramify and are lost upon the parietes of the vein and duct, almost in the same 
 manner as the bronchial arteries are distributed upon the divisions of the air tubes. I 
 must, therefore, conclude that the hepatic artery furnishes for the liver the nutritious 
 vessels (vasa vasorum) of the vena portae and hepatic ducts ; and this will explain the 
 disproportion between its cahber and the size of the Uver. 
 
 The subdivisions of the hepatic veins, which follow a separate course, present a sim 
 ^ilar peculiarity to that observed in the splenic vein, viz., a multitude of pores or holes 
 
 inter-lobular veins. This appearance is peculiar to the sub-lobular veins, the canals for vehich alone are form- 
 ed by the bases (c c) of the lobules. The portal canals (g,fig- 165) are formed by their capsular surfaces, and 
 the openings (d), seen in the interior of the small divisions of the vena portae, correspond to the inter-lobular 
 spaces, not to the centres of the lobules. The sub-lobular veins anastomose with each other (this the divis- 
 ions of the vena portae never do), and unite to form the hepatic venous trunks (H,fig. 166), into which no in- 
 tra-lobular veins open, nor do tlie bases of any lobules rest upon them.] 
 
 * [From this statement the ducts must be excepted ; they do not communicate with the bloodvessels. — (See 
 note, p. 395.)] « 
 
 t " Quilibet acinus hepatis e glomeroso constat, vel e particulis arteriE, venae portarum, venie hepaticae, duc- 
 tus biliferi et vasorum absorbentium, cujus formam rosie sic dictie Damascenae imaginem pingere nobis licet," 
 —(Corp. Hum. Fab., t. vi., p. 180.) t See note, p. 395. 
 
THE LIVER. g§5 
 
 by which very small veins open directly into them. Their ramifications are much less 
 numerous than those of the vena portae. 
 
 The result of the injections described above also explains the difference in colour be- 
 tween the centre and the circumference of each granule ; it shows, moreover, that one 
 part of the granule is impermeable to injections ; and its spongy nature, resembhng that 
 of the pith of the rush or elder, is apparent even to the naked eye, in a section of a liver 
 thus injected, when viewed by a strong light. 
 
 To resume, then, it may be said that the liver is composed of ovoid, elliptical, or, rath- 
 er, polyhedral granules, moulded closely upon each other. Each granule has its proper 
 fibrous capsule ; and all the capsules are united together by prolongations, which also 
 connect them with the general cellular investment of the liver, and with that extension 
 of it called the capsule of GUsson. The granules are independent of each other. Each 
 of them consists of a spongy tissue, impermeable to injections ; of a biliary duct proceed- 
 ing from its centre ; of a venous network foimed by the hepatic veins ; of another ve- 
 nous network belonging to the vena portae ; and of a very delicate arterial network deri- 
 ved from the hepatic artery, which is ramified upon the parietes of the vena portae and 
 biliary ducts. Such is the structure of the hver.* It remains for me now to examine its 
 excretory apparatus. 
 
 The Excretory Apparatus of the Liver. 
 
 The excretory apparatus of the liver consists of the hepatic duct, of the cystic duct, 
 of the gall-bladder, and of the ductus communis choledochus. 
 
 The hepato-cystic canals, t admitted by some authors as constant or occasional in man, 
 can be easily shown in the lower animals, but do not exist in the human species. 
 
 TTie Hepatic Duct. — The hepatic duct arises in the granules of the liver by hepatic radr 
 KleSjt which, by uniting successively like veins, constitute small and then larger branch- 
 es. These latter all converge towards the transverse fissure of the liver, where they 
 terminate ultimately in two trunks of almost equal size, which join each other at a very 
 obtuse angle, and form the hepatic duct {d,fig. 164). The condition of the branches of 
 the hepatic duct in the transverse fissure is extremely variable : thus, sometimes the 
 trunk of the right side is larger than that of the left, and sometimes the opposite is the 
 case. Frequently several branches join the trunks late in the transverse fissure ; but, 
 whatever be the nature of these variations, the right trunk never corresponds exactly to 
 the right lobe of the liver, nor the left to the left lobe. 
 
 All the divisions and subdivisions of the hepatic duct^ are contained in the capsule of 
 Glisson, together with the ramifications of the vena portaj and hepatic artery, to which 
 
 * Structure of the Lobules. — [It appears from the preceding note, that while several branches of the vena 
 portae and hepatic artery enter, and several of those of the hepatic duct pass out at the capsular surface of 
 each lobule, only a single branch of the hepatic vein emerges from its base ; within the lobules, the following 
 is the arrangement of these vessels : 
 
 The branches from the inter-lobular (portal) veins Cp p p,Jig. 167) form in the outer portion of each lobule 
 a venous plexus {I I), consisting of branches radiating towards the centre, rv jg~ 
 
 connected by others passing transversely ; these veins become capillary, e • ' • 
 
 ramify upon the biliary ducts, and terminating in the branches of the intra- 
 lobular (hepatic) vein (h), which correspond in number with the processes 
 
 on the surface of the lobule, ultimately unite to form the central vein that «:;>^^^Ji^^^/^}^^'^i^'^ 
 passes out at its base. 
 
 The lobular arteries are few in number, and, according to Kieman, end in 
 branches of the vena portse, and not directly in those of the hepatic vein. 
 Miiller inclines to the more commonly received opinion, that the three kinds 
 of bloodvessels communicate with each other. No communication, how- 
 ever, exists, as stated by M. Cruveilhier, between the bloodvessels and the 
 biliary ducts, which, like the ducts of other glands, are an independent system of vessels. According to Mr. 
 Kieman, the ducts form a reticulated plexus, occupying principally the outer portion of each lobule (as shown 
 at 6 b, jig. 168, which is a diagram copied from Mr. Kieman's paper). 
 MUUer expresses doubts as to the anastomosis of the ducts, and thinks it 
 probable, from analogical observation, that they terminate in tufts of tubes 
 having blind extremities. 
 
 The islets formed between the radiating and transverse branches of the 
 lobular (portal) veins (I, fig. 167) correspond to the acini of Malpighi, and 
 contain the biliary ducts with their capillary bloodvessels, and also a pecu- 
 liar tissue, which occupies all the intervals between the several kinds of 
 vessels, and consists, according to Krause, of hexagonal, nucleated cells, 
 having several bright points in them, like globules of oily matter. 
 
 The appearance of two substances in the liver can now be explained ; it 
 does not depend on the biliary ducts being situated in the centre, and the '' ' ' 
 
 veins nearer to the circumference of each lobule (sec p. 391, 394), but in a 
 partial congestion of either the portal or hepatic system of veins. 
 
 In portal congestion, the margins of the lobules are dark, and their centres pale ; it is very rare, and has 
 been seen only in children. 
 
 Of hepatic venous congestion there are two stages : in the first, the centre of each lobule is dark, and the 
 margin pale (fig. 166) ; it constitutes passive congestion, and is the common state of the liver after death : in 
 the second, the congestion extends to the portal veins in the iuter-lobular_/isiures, but not to those in the inter- 
 lobular spaces, or points at which those fissures meet, which spaces are then seen to occupy the centre of each 
 pale isolated spot : this is active congestion of the liver ; it occurs in diseases of the heart, and in acute dis- 
 eases of the lungs and pleura.] 
 
 + [/. c, canals passing directly from the liver into the gall-bladder.] t See note, suprA 
 
 <) [Excepting those within the" lobules.] 
 
396 SPLANCHNOLOGY. 
 
 they are connected by loose cellular tissue. The trunks of the hepatic duct lie at the 
 bottom of the transverse fissure, and are hid by the trunk of the vena portse and the 
 branches of the hepatic artery. The hepatic duct {t, fig. 169), thus formed by the union 
 of the two trunks which occupy the transverse fissure, passes downward and to the right 
 side for about an inch and a half, and then unites at a very acute angle with the cystic 
 duct (s), to form the ductus communis choledochus (c ; and x, fig. 154). In this course 
 the duct is contained in the gastro-hepatic omentum, together with the vena portas, which 
 is behind it, and the right branch of the hepatic artery, which is in front of it. A great 
 quantity of loose cellular tissue unites the duct to these vessels. 
 
 The Gail-Bladder. Dissection. — ^A gall-bladder filled with bile may be studied without 
 any preparation : if it is empty it must be distended, either with a fluid or vpith air. A 
 beautiful preparation of the gall-bladder may be made for preservation by drying it after 
 inflation, or by filling it with fat, which is afterward removed by oil of turpentine. 
 
 The gall-bladder {cystis fellea, g,fig. 164) is the reservoir of the bile. It is situated at 
 the lower surface of the right lobe of the liver, occupying a particular fossa (the fossa of 
 the gall-bladder) on the right of the longitudinal fissure, from which it is separated by the 
 lobulus quadratus. It is held in this place by the peritoneum, which, in the majority of 
 instances, merely passes below it, but, in others, almost entirely invests it, and thus at- 
 taches it to the liver by a sort of mesentery. In this latter case it is at some distance 
 from the liver, as in certain animals. 
 
 Its fcrrm. is that of a pear, or of a cone with a rounded base ; it is directed obliquely, 
 so that its great extremity (g,figs. 155, 161) looks forward, downward, and to the right ; 
 and its small extremity, backward, upward, and to the left side. 
 
 Size. — The small size of the gall-bladder corresponds with that of the rest of the ex- 
 cretory apparatus of the bile, and is strongly contrasted with the great bulk of the liver. 
 This difference becomes still more striking if we compare, on the one hand, the kidney 
 with the liver, and, on the other, the urinary bladder with the gall-bladder. It is true, 
 however, that all the urine must pass through the former, while a part only of the bile is 
 deposited in the latter. 
 
 The size of the gall-bladder, however, is subject to considerable variety ; it sometimes 
 acquires three, four, or even ten times its usual size from retention of the bile, in conse- 
 quence of obstruction in the ductus choledochus.* Cases have been recorded in which 
 it contained six, eight, or ten pounds of bile, but this I can scarcely credit. On the oth- 
 er hand, it is sometimes closely contracted round a small calculus, while the cystic duct 
 is completely obliterated, and reduced to a fibrous cord. It must undoubtedly have been 
 such cases as these that have been regarded as examples of congenital absence of the 
 gall-bladder. 
 
 Relations. — In order to facilitate our description, we shall consider the gall-bladder as 
 consisting of a body, a fundus, and a neck. 
 
 The body is conical, and has the following relations : below, where it is covered by the 
 peritoneum, it is in relation with the first portion of the duodenum, and the right extrem- 
 ity of the arch of the colon. It is not unfrequently found in contact with the pylorus, or 
 even with the pyloric end of the stomach. Sometimes it is united by accidental or nor- 
 mal adhesions to the duodenum and arch of the colon. These relations account for the 
 yellow or green discoloration which always takes place after death in those parts of the 
 alimentary canal that are in contact with the gall-bladder ; and also for the passage of 
 biliary calculi into the duodenum, the colon, and the stomach. It is not very rai-e to find 
 the gall-bladder applied by its whole length to the right kidney : this relation can only 
 occur after descent of the duodenum and transverse colon. Above, the body of the gall- 
 bladder adheres to the cystic fossa by a more or less loose cellular tissue,! and by ar- 
 teries and veins, but never in the human subject by biliary, i. e., hepato-cystic, ducts. 
 
 The fundus of the gall-bladder {g,fig. 161), entirely covered by the peritoneum, gen- 
 erally projects beyond the anterior margin of the liver, and comes into relation with the 
 abdominal parietes, opposite the outer border of the right rectus muscle, immediately 
 below the costal cartilages near the anterior extremity of the tenth rib. When distend- 
 ed with bile or calculi, the fundus of the gall-bladder becomes prominent, so as to raise 
 the abdominal parietes, through which it has been felt in emaciated individuals. It has 
 even been stated that the noise made by the calculi may be heard on percussion. This 
 relation explains the possibility of the occurrence of abdominal biliary fistulae, and why 
 calculi may escape through such openings : on it, also, is founded the scheme for ex- 
 tracting the calculi by an operation analogous to that performed for stone in the urinary 
 b adder, and which I should not have mentioned had it not been proposed by J. L. Petit. 
 
 The relations, as well as the size of the fundus of the gaU-bladder, present many vari- 
 
 * Anrf.her cause of enlargement of the gall-bladder is the obstruction of its neck by a calculus : but, in- 
 stead of bile, it then contains a limpid serum, and, in fact, is converted into a serous cyst. The tumour thus 
 formed may t)e compared to the lachrymal tumour in cases of obstruction of the lachrymal puncta or canals. 
 
 t This cellular tissue may become inflamed, and, if pus be formed, it may pass into the gall-bladder, while 
 the bile escapes into the cellular tissue, and hence death may ensue. I have observed, in a very short space 
 of time, three examples of this lesion, which, perhaps, has not been thoroughly examined ; and several cases 
 have been shown me under the name of gangrene of the gall-bladder. 
 
THE LIVER. 3g7 
 
 eties. The fundus, or that part which projects beyond the Uver, is sometimes as large 
 as the body. I have seen this part of the gall-bladder turned back at a right angle upon 
 its body, and reaching the umbilicus. It may be conceived, that the differences in the 
 form and situation of the liver must greatly influence the situation of the fundus of the 
 gall-bladder, which I have found in the hypogastrium and in the right iliac fossa, either 
 with or without adhesion to the neighbouring parts. 
 
 The neck or apex of the gall-bladder is twice bent suddenly upon itself, like an italic S, 
 having its three portions in contact. It would appear, in some cases, that these two 
 curves resemble the thread of a screw. This double curvature may be easily elTaced by 
 removing the peritoneum with the subjacent cellular tissue. The limits between the 
 neck and the body of the gall-bladder on the one hand, and between the neck and the 
 cystic duct on the other, are marked externally by a constriction. 
 
 The internal surface of the gall-bladder is tinged either green or yellow, according to 
 the colour of the bile ; but this staining is the effect of transudation after death ; its nat- 
 ural colour is a whitish gray. Moreover, the internal surface is irregular, like shagreen, 
 and has some crests or prominences arranged upon it in polygons, and again subdivided 
 by smaller crests, like the reticulum in the stomach of ruminantia ; so that, when ex- 
 amined by a strong lens, it appears divided into a number of small and very distinct al- 
 veoli : some highly-developed papillae or villi, of a very irregular shape, are also found 
 upon it. As to the object of either the crests or the papillae, or whether they favour ab- 
 sorption by multiplying the surface, we are altogether unable to decide. 
 
 Opposite each of the two curves of the S, described by the neck of the gall-bladder,, 
 we find a very large valve. The two valves, which are in opposite directions, as well 
 as the curves, result from the alternate inflection of the neck itself, and are efl^aced by 
 straightening that part. The portion of the neck between the two valves is not unfre- 
 quently dilated into an ampulla. A calculus is often formed in this intermediate portion, 
 where it remains, as it were, encysted, and intercepts the course of the bile ; and that 
 the more easily, because the valves greatly contract the openings from the neck into the 
 body of the bladder, and into the cystic duct. Moreover, these valves are opposed nei- 
 ther to the entrance of the bile into, nor to its exit from, the bladder. 
 
 Structure. — Proceeding from without inward, we find that the gall-bladder is composed 
 of, 1. A peritoneal coat, which is reflected from the lower surface of the liver upon the 
 bladder, completely invests its fundus, forms a more or less incomplete covering for its 
 body and neck, and is continuous with the anterior layer of the gastro-hepatic omentum. 
 2. An areolar fibrous coat, which forms, as it were, the framework of the bladder, and pre- 
 vents its sudden distension, though it will yield to a long-continued distending force ; 
 but I have not been able to see the muscular fibres admitted by some authors, and which 
 can be so easily detaonstrated in the larger animals, the ox in particular. 3. An interned 
 mucous membrane, the principal characters of which I have noticed when speaking of the 
 internal surface of the gall-bladder : it presents some folds, which may be easily distin- 
 guished from the borders of the alveoh, because they are readily effaced by distension. Af- 
 ter the most attentive examination, I have been unable to recognise any crypts or follicles. 
 
 The gall-bladder receives one very considerable artery, the cystic branch of the hepatic. 
 The cystic vein terminates in the vena portae. The lymphatic vessels are very numerous, 
 and easily demonstrated ; they are sometimes tinged by the colouring matter of the bile. 
 Its nerves are derived from the hepatic plexus. 
 
 The Cystic Duct. — The cystic duct {,s,fig. 169), or excretory duct for the bile, is the 
 smallest of all the biliary canals : it is not unconunon, however, to find it of an equal or 
 even larger size than the others, in which case there has always been some obstacle to 
 the flow of the bile through the ductus communis choledochus (c). It conm[iences at the 
 neck of the gall-bladder, passes downward and to the left side for about an inch, and 
 unites at a very acute angle with the hepatic duct (t). 
 
 It is not straight, but inflected, and, as it were, sinuous. 
 
 Relatio-ns. — It is situated in the substance of the gastro-hepatic omentum, in front of 
 the vena cava, the cystic artery being on its left side. Its internal surface is remarkable 
 for its valves, which are indefinite in number ; according to Soemmering, there are from 
 nine to twenty, but this appears to me to be an exaggeration : I have counted from five 
 to twelve. These valves are concave at their free margins, irregular, alternate, oblique, 
 transverse, sometimes even vertical, and united together by small oblique valves. In 
 order to understand their structure, a cystic duct must be examined under water, or, rath- 
 er, an inflated and dried specimen. This alternate arrangement of the valves some- 
 times gives a spiral appearance to the inner surface of the cystic duct.* These valves, 
 which only exist in man, perhaps on account of the erect position peculiar to him, are 
 not effaced, like the valves in the neck of the gall-bladder, by such dissection as will al- 
 low of straightening of the duct. Small calculi are occasionally met with in the inter- 
 vals between the valves, giving to the cystic duct a nodulated appearance, and intercept- 
 ing the flow of the bile. Moreover, the valves of the cystic duct are not more opposed 
 to the descent than to the ascent of the bile. It is even probable that they facilitate the 
 
 * " Quae possint aliquam spiralis fabricse imagincm ferre." — {Holler, torn, vi., liv. xxiii., p. 530.) 
 
398 SPLANCHNOLOGY. 
 
 ascent of the bile into the gall-bladder by supporting the column of liquid, like the valves 
 of the veins. Perhaps they are also intended to retard the course of the bile from the 
 gall-bladder towards the ductus choledochus. From their appearing sometimes to have 
 a spiral arrangement, M. Amussat has advanced a very ingenious opinion : that the as- 
 cent of the bile is effected by a contrivance like an Archimedes' screw. But an Archi- 
 medes' screw only causes the ascent of a liquid when a rotatory movement is communi- 
 cated to it, and how can such a movement be performed by the cystic duct 1* 
 
 The Ductus Communis Choledochus. — The ductus communis choledochus ( xo^, bile, 
 doxo^, containing ; c, c. Jig. 169), the last excretory canal of the bile, seems to be formed 
 Fig. 169. by the union of the hepatic (0 and the cystic 
 
 ducts («). Another, and, perhaps, more simple 
 manner of viewing the excretory cansils of the 
 liver, would be to consider the hepatic duct as 
 giving off to the right, after a certain course, the 
 cystic duct, which, after passing backward, di- 
 lates into an oval ampulla to form the gall-blad- 
 der ; and the ductus choledochus as nothing 
 more than the continuation of the hepatic duct. 
 The direction of the ductus choledochus is, in 
 fact, the same as that of the hepatic duct, i. e., 
 obliquely downward, a little to the right, and 
 backward : there is no line of demarcation be- 
 tween these two ducts : in the natural state 
 there is no marked difference in their diame- 
 ters : the ductus choledochus, when collapsed, is 
 about as large as a moderately-sized goosequill. 
 't The same causes give rise to dilatation of the 
 
 ductus choledochus and of the hepatic duct. I have seen the former as large as the duo- 
 denum. {Anat. Pathol, avec planches.) Its length is from two to two inches and a half 
 Relations. — In the first part of its course, before it reaches the duodenum, the ductus 
 choledechus is included in the gastro-hepatic omentum, in front of the vena portae, and 
 below the hepatic artery, having the right gastro-epiploic artery along its left side, and 
 surrounded by loose cellular tissue, a great number of lymphatic vessels, and several 
 lymphatic glands. Having reached the duodenum, opposite the first flexure of that in- 
 testine, it passes behind and to the inner side of its second portion, and is there received 
 into a groove, or, more commonly, into a complete canal, formed for it by the pancreas. 
 Lastly, it penetrates very obliquely into the substance of the duodenum, about the mid- 
 dle of its second or vertical portion, perforates the muscular coat, passes between that 
 and the fibrous coat, then between the fibrous coat and the mucous membrane, elevating 
 the latter when distended with bile or by a probe, and after a course of about seven or 
 eight lines between the coats, opens into the duodenum, about the lower part of the sec- 
 ond portion, at the summit of a nipple-like eminence (above c), which is more or less 
 prominent in different subjects. 
 
 In this third portion of its course the ductus choledochus is in relation with the pan- 
 creatic duct (m), which is situated on its left. Opposite the base of the eminence above- 
 mentioned, the two ducts unite, or, rather, the pancreatic duct opens into the ductus 
 choledochus ; so that, at its termination, the latter may be regarded as a canal having a 
 triple origin, viz., an hepatic, a cystic, and a pancreatict 
 
 Internal Surface of the Ductus Hepaticus and Ductus Choledochus. — ^The internal surface 
 of both the hepatic duct and the ductus choledochus is characterized by the absence of 
 valves, though traces of valves are occasionally met with in the ductus choledochus ; 
 by the absence of the alveolar structure observed in the gall-bladder ; and by having a 
 niultitude of openings or well-marked pores, which are considered as belonging to mu- 
 ciparous follicles, and are apparently formed by an interlacement of fasciculi, having a 
 fibrous character, and intersecting each other at very acute angles. The ductus chole- 
 dochus and the hepatic duct are of uniform caliber throughout their whole length. The 
 ductus choledochus is contracted a little in its third or duodenal portion ; it dilates into 
 an olive-shaped ampulla, opposite the base of the papilla in the duodenum, and opens by 
 an extremely small orifice or mouth : hence the reason why biliary calculi are so fre- 
 quently arrested in the ampulla of the ductus choledochus. 
 From the narrowness of the duodenal orifice of the ductus choledochus, from the mo- 
 
 * Another opinion, founded upon the existence of the valves, is that of Bachius, who, believing that he had 
 shown that the valves prevent the ascent of the bile from the hepatic duct into the gaU-i)ladder, has advanced 
 very singular views concerning the formation and uses of the bile. The bile, according to him, is formed in 
 the gall-bladder, and carried l)y the cystic duct into the hepatic duct and the ductus choledochus. By his 
 theory, the bile which reaches the liver through the hepatic duct assists greatly in sanguification. This opin- 
 ion, altogether erroneous as it is, has perhaps exercised a great influence in science, by contributing to eradi- 
 cate the idea of the bile being an acrid, corrosive, and essentially injurious excrementitial fluid. 
 
 t Hence the definition of SoDminering : " Ductus choledochus, id est, ductus hepaticus, cysticus, et pancreatir 
 cus, in unum conflati," — ICorpor. Hum. Fabric, tom.\i., p. 186.) 
 
THE LIVER. 
 
 ▼able or yielding nature of the eminence upon which it opens, and from the oblique course 
 of the duct through the substance of the walls of the duodenum, it follows that the bile 
 and the pancreatic fluid may pass freely from the ductus choledochus into the duodenum, 
 but cannot regurgitate from the duodenum into the duct. On this subject I have made 
 several experiments. I have forcibly injected both water and air into the duodenum, 
 included between two ligatures, but nothing entered into the biliary canals : on the other 
 hand, I have injected the same fluids from the gall-bladder into the duodenum, which I 
 was thus able to distend at pleasure. But then, on compressing the bowel thus distend- 
 ed with great force, I have never been able to cause the slightest reflux into the biliary 
 caneils.* 
 
 At the union of the cystic and hepatic ducts there is a very long spur-shaped process, 
 formed by the hning membrane reflected upon itself At the junction of the ductus cho- 
 ledochus and the pancreatic duct there is also a similar process, which I have seen ex- 
 tending down to the duodenal orifice. In neither situation do these processes prevent 
 the fluid of one canal from passing into the other. Thus, the cystic bile might flow back 
 into the hepatic duct, the pancreatic fluid might regurgitate into the ductus choledochus, 
 and, on the other hand, the bile might enter the pancreatic duct, if these canals were not 
 habitually full. Moreover, the spur-shaped process between the ductus choledochus and 
 the pancreatic canal cannot arrest the flow, either of the bile or the pancreatic fluid, by 
 being applied to the orifice of the one or other duct. 
 
 Structure of the Biliary Ducts. — ^AU the biliary ducts have a similar structure : they 
 have an internal mucous membrane, continuous on the one hand with the lining mem- 
 brane of the gall-bladder, and on the other with that of the duodenum ; it is thin, and 
 provided with slightly-developed papillae ;t a. proper membrane, composed of a dense are- 
 olar tissue, generally regarded as fibrous, but which appears to me analogous to the tis- 
 sue of the dartos condensed ; a cellular layer connecting these canals to the surrounding 
 parts ; and, lastly, the peritoneimi, which forms a very incomplete accessory tunic for 
 them. 
 
 Thus constituted, the biliary ducts have very thin walls, so that they collapse like 
 veins, and are extremely dilatable. In certain cases of retention of the bile we find the 
 ductus choledochus and the hepatic duct as large as the duodenum, the divisions of the 
 hepatic duct dilated in proportion, and the tissue of the liver more or less atrophied by 
 the compression to which it has been subjected. 
 
 Development of the Liver. — The development of the liver is one of the most important 
 subjects in its history. Under this head we have several points to consider : 
 
 1. The time of its appearance is anterior to that of any other organ :t in the first days 
 of intra-uterine life it may be distinguished by its colour in the midst of the ceUular mass 
 which represents the foetus. 
 
 2. In size the liver is relatively larger as it is examined at an earlier period of devel- 
 opment. Thus, according to Walter, in the embryo of three weeks it forms one half the 
 weight of the whole body. This enormous proportion is maintained during the first half 
 of intra-uterine life. After this period its growth is slower, while that of the other or- 
 gans is proportionally increased, so that at birth the weight of the liver is one eighteenth 
 that of the whole body.ij After birth the liver undergoes an absolute diminution ; some 
 authors have even affirmed that a comparison of the weight of the liver in new-bom in- 
 fants and in children of nine or ten months old, gives a difference of one fourth in favour 
 of the former. It is generally said that the difference in size affects the left rather than 
 the right lobe ; but this has not appeared evident to me. Towards the age of puberty 
 the liver has the same relative bulk as at later periods. Attempts have been made to 
 ascertain the proportion between the weight of this organ and that of the body, and it 
 has been said that it forms one thirty-sixth part of the whole body. But what relation 
 can be established between two terms, one of which, viz., the weight of the body, is 
 subject to continual variations 1 In old age the liver is smaller than in the Eidult, a dim- 
 inution apparently in unison with that which occurs in all the other organs. 
 
 3. The differences in the situation of the liver are connected with its variations in size : 
 thus, in the first half of intra-uterine life, the liver occupies the greatest part of the ab- 
 domen, and is in relation with certain regions in which it is not found at more advanced 
 stages. In the earUest periods it descends as low as the crest of the ilium, and when 
 the abdomen is opened it presents the appearance of a red mass, beneath which are 
 
 * How can this fact be reconciled with another no less incontestable, viz., the passage of lumbrici into the 
 biliary ducts 1 The reason is, that the lumbricus is a foreign body, which has a power of selection, and is able 
 to overcome an obstaCie, to seek for the orifice of the ductus choledochus, and to introduce itself within it. 
 
 t [Numerous follicles are found in the ductus communis and in the hepatic duct, and all its subdivisions ; 
 according to Mr. Kiernan, even in the smallest that can be examined. In the larger branches they are ar- 
 ranged irregularly; in the smaller ones, in two longitudinal rows, along opposite sides of the duct.] 
 
 t [In the embryo of the bird the liver is developed by a conical protrusion of the walls of the intestinal ca- 
 nal into a granular mass or blastema. — (See Milller^s Phys. by Baly, p. 448.) The rudiments of the cerebro- 
 gpinal axis, of the heart, and of the intestinal canal, appear previously to the liver.] 
 
 f) I have had occasion to notice, at the Matemite, the very great differences in the size of the liver in in- 
 fants at birth, for which I have been unable to find any sufficient reason. There ai'.' some well-formed in 
 fauts in whom the liver at birth is not relatively larger than that of adults 
 
400 SPLANCHNOLOGY. 
 
 placed the other abdominal viscera. During the second half of intra-uterine life, and at 
 birth, it occupies only a part of the abdomen ; but it still corresponds to a considerable 
 extent of the abdominal parietes : hence the ease with which it is ruptured by pressure 
 upon the abdomen of a new-born infant. One fact on record seemed to me to prove, 
 that in a first labour, where the feet presented, the pressure of the genital organs of the 
 mother was S'ufficient to produce this result. — (Vide Proces-verbal de la Distribution des 
 Prix de la Maternite, 1832.) 
 
 In the eariiest periods the falciform ligament of the liver corresponds to the median 
 line of the body ; at birth it is a little to the right of that line, and is afterward removed 
 still farther in the same direction. 
 
 4. The great size of the liver during intra-uterine life is connected with the existence 
 of the umbilical vein, by which the foetus receives the blood returned from the placenta, 
 that is to say, all the blood necessary for its nutrition. The rapid diminution of the 
 liver after birth is probably owing to the obliteration of this vein. It is a very remark- 
 able fact, that the persistence of this vein in the adult is not accompanied by an unusu- 
 ally large liver. In one particular case of persistence of the umbilical vein the liver was 
 of a very small size. — {Anat. Path, avec planches, liv. xvii.) 
 
 5. The tissue of the liver of the foetus is of a pale red colour in the early periods, and 
 of a deep brown near the full term of pregnancy ; its colour becomes lighter after birth. 
 The liver contains a greater quantity of blood before than after birth. Its tissue is the 
 less consistent the earlier the stage of development at which we examine it, and its soft- 
 ness is accompanied with great fragility. 
 
 6. The distinction between what are called the two substances of the liver is not ap- 
 preciable during intra-uterine life. It only becomes apparent after birth. 
 
 Functions. — The liver is the secreting organ of the bile. The bile is secreted in the 
 glandular granules by an unknown process. Doubts are stiU entertained as to whether 
 the materials from which the secretion is formed are conveyed by the hepatic artery or 
 the vena portae.* The opinion advanced by some modern authors, that the yellow sub- 
 stance of the liver is the only part concerned in the secretion of the bile, and that the 
 brown substance has other uses, is a purely gratuitous hypothesis. 
 
 The bile traverses the several ramifications of the hepatic duct, and, having arrived in 
 the principal duct, it may either enter directly into the duodenum by the ductus chole- 
 dochus, or it may pass into the gall-bladder by the cystic duct. This retrograde move- 
 ment towards the gall-bladder has much occupied the attention of physiologists : perhaps 
 it may be explained by the narrowness of the duodenal orifice of the ductus choledochus, 
 by the elasticity of that canal, and especially by the pressure exercised on its duodenal 
 portion by the circular fibres of the duodenum. The gall-bladder and the cystic duct are 
 not indispensable to the elimination of the bile. Nothing is more common than to find 
 the excretory apparatus of the liver in old subjects reduced to the hepatic duct and the 
 ductus choledochus. 
 
 Has the liver any other function besides that of secreting bile 1 The disproportion ex- 
 isting between the size of that organ and of its excretory apparatus, and also the enor- 
 mous bulk of the liver during foetal life, i. e., at a time when the secretion of bile is at 
 its minimum of activity, are both in favour of the opinion that the liver has some addi- 
 tional function ; and if, again, we consider that, in the adult, a very important system of 
 veins is distributed to the liver, and that in the foetus it receives the blood from the veins 
 of the foetal portion of the placenta, we shall be led to presmne that the unknown func- 
 tions of this organ are in some way connected with the process of sanguification. 
 
 The Pancreas. 
 
 Dissection. — The pancreas may be seen through the gastro-hepatic omentum, after 
 drawing down the stomach, without any dissection. In order to expose it, turn the 
 stomach upward (see fig. 154) after having divided the two layers of peritoneum which 
 proceed from its greater curvature to form the great omentum. It may also be ex- 
 posed by turning the arch of the colon upward, and dividing the inferior layer of the 
 transverse mesocolon. The excretory duct is situated in the interior of the organ. In 
 order to dissect it, the glandular substance which covers it must be very carefully re- 
 moved towards tlie middle and the right extremity of the gland. It may be injected from 
 the ductus choledochus, after the vertical portion of the duodenum has been included be- 
 tween two ligatures : when the duodenum is filled with the injection, the pancreatic duct 
 becomes filled in its turn. It may also be injected from the ductus choledochus after hav- 
 ing passed a ligature round the projection or ampulla which is common to the two ducts. 
 
 The -pancreas {Trdv-Kpeag, all flesh) is a glandular organ annexed to the duodenum, with 
 which it has immediate relations : it is situated transversely and deeply behind the stom- 
 ach, and in front of the lumbar vertebrae. 
 
 * [From the researches of Mr. Kiernan (see note p. 395), it would appear that the blood of the vena ports is 
 directly concerned in the secretion of the l)ile, while that of the hepatic artery is only indirectly concerned, 
 i. e., after it has afforded nutrition to the tissue and vessels of the liver, and has entered the branches of the 
 ■'•ena portae, and thus become portal blood.] 
 
THE PANCREAS. 401 
 
 Form and Size. — In form, the pancreas resembles no other gland ; it is transversely 
 oblong, flattened from before backward, large at its right extremity, where it presents a 
 sort of angular expansion like a hammer, and gradually tapering towards its left extrem- 
 ity : hence the division of this organ into a head, body, and tail. Its long or transverse 
 diameter is measured by the interval between the concavity of the duodenmn (e e) and 
 the spleen (A). The size and weight of the pancreas present many varieties. Its weight 
 is generally from two to two and a half ounces, but may reach six ounces. The pan- 
 creas is sometimes found atrophied, and in one case of this kind it did not exceed an 
 ounce in weight. 
 
 Relations. — Its anterior surface, convex and covered by the peritoneum, is in relation 
 with the stomach, which moves freely upon it. In certain cases of disease, adhesion 
 between the pancreas and the stomach takes place, so that in chronic ulceration of the 
 latter we find the pancreas supplying the place of large portions of the walls of the stom- 
 ach which had been destroyed. When the stomach is situated lower down than usual, 
 the pancreas has relations either with the liver or with the anterior walls of the abdo- 
 men, from which it is separated only by the gastro-hepatic omentum, so that it may be 
 felt with the greatest ease through the abdominal parietes.* In such cases, even expe- 
 rienced practitioners have not unfrequently been led to infer the presence of scirrhus of 
 the pylorus. The pancreas is also in relation, in front, with the first portion of the duo- 
 denum, and with the angle formed by the ascending and transverse colon. 
 
 Its posterior surface is concave, and corresponds to the vertebral column, opposite the 
 first lumbar vertebra ; it is separated from the spine, however, by the splenic and the 
 superior mesenteric veins, and by the commencement of the vena portae. The two last- 
 mentioned veins are lodged in a deep groove, or, rather, almost complete canal, formed in 
 the pancreas, which also includes the superior mesenteric artery and its surrounding 
 plexus of nerves. A great number of lymphatic vessels and glands, the pillars of the 
 diaphragm (d d), the vena cava on the right side, and the aorta on the left, also separate 
 the pancreas from the vertebral column. To the left of the spine it is in relation vrith 
 the left supra-renal capsule and kidney, and the corresponding renal vessels. The rela- 
 tion of the pancreas to the aorta is important ; it is through the pancreas that the pulsa- 
 tions of that vessel are felt in the epigastrium in emaciated individuals, and it is here 
 that the vessel may be compressed. 
 
 Its upper border is thick, and is grooved for the reception of the splenic artery, which 
 often runs in a sort of hollow canal formed in the substance of the gland through its en- 
 tire length. It also has relations with the first portion of the duodenum (e), with the 
 lobulus Spigelii, and with the coeUac axis (<). The thickness of this border has led some 
 anatomists to say that the pancreas is prismatic and triangular. 
 
 Its lower border is much tliinner than the upper, and is bounded by the third portion of 
 the duodenum, from which it is separated on the left by the superior mesenteric vessels 
 {rOf the artery). 
 
 Its right, or duodenal, or great extremity is in contact with the duodenum and the duc- 
 tus choledochus. This extremity presents a very remarkable arrangement ; it is curv- 
 ed upon itself from above downward, like the duodenum, by the concavity of which it is 
 circumscribed ; then, having reached the third portion of the bowel, it passes transverse- 
 ly to the left, behind the superior mesenteric vessels, and forms the posterior wall of 
 the canal in which they are situated. This reflected portion, arranged in the form of 
 a whorl, is sometimes detached from the rest of the gland, on which account it has been 
 called the lesser pancreas. By its great extremity the pancreas is, as it were, attached 
 to the duodenum, beyond which it projects in front, but especially behind : it accompa- 
 nies this intestine in all its displacements, so that when the duodenum is situated lower 
 down than usual, which happens in displacements of the stomach downward, the head 
 of the pancreas is always removed in the same direction. 
 
 Its left, or splenic, or small extremity is narrow, and touches the spleen, upon which it 
 is flattened and blunted, and sometimes slightly enlarged. It is seen, then, that in its 
 relations to other parts, the pancreas has a great analogy with the salivary glands. Thus, 
 large vessels are situated near and penetrate this gland, which forms a sort of covered 
 passage for them, and is moved by their pulsations. The diaphragm, the duodenum, and 
 the stomach, also tend to disturb and press upon the pancreas. 
 
 Structure. — The analogies in structure between the pancreas and the salivary glands 
 are no less numerous, and fully justify the name of abdominal salivary gland given to it 
 by Siebold : it has the same whitish colour, the same density, t and the same arrange- 
 ment into lobes, which are themselves divisible into lobules. The identity is such that 
 it would be impossible to distinguish a portion of the pancreas from a part of a salivary 
 
 * This condition may be foretold : it occurs whenever the vertebral column can be felt immediately behind 
 the parietes of the abdomen. I have never met with it excepting in emaciated individuals, where a great 
 part of the small intestine occupied the cavity of the pelvis. It is probably the traction exercised by the small 
 intestine contained in the pelvis that occasions the low position of the stomach. 
 
 t The pancreas sometimes assumes an extreme density, strongly resembling that of scirrhus. In such a 
 case it is necessary to make sections of it, to be assured of the perfect soundness of the glandular tissue. This 
 stony hardness generally occurs along with atrophy of the organ 
 
 Ee E 
 
ii402 Sl'LANCHNOLOCfY. 
 
 gland. Wlicn boiled, they both have the same aspect and the same taste. There is no 
 fibrous capsule, properly so called, but some fibrous lamellae, which separate the lobes 
 and lobules. Cellular tissue is tolerably abundant. Fat is not uncommonly met with, 
 either on the surface or in tlie substance of the pancreas ; I have even seen cases of atro- 
 phy of the gland, in which fat appeared to have been substituted for the glandular substance. 
 
 The determination of the structure of the pancreas, like that of all glands, involves two 
 considerations, viz., the texture of each lobule, and the arrangement of the vessels and 
 nerves in the substance of the gland. With regard to the first point, I shall merely re- 
 fer to what has been already stated respecting the salivary glands.* The arrangement 
 of the vessels is perfectly well known. 
 
 As in the salivary glands, the arteries enter the pancreas at a great number of points. 
 They are very numerous and very large, considering the small size of the organ : they 
 arise from the hepatic, the splenic, and the superior mesenteric. The principal arterj" 
 is called the pancreatico-duodenalis. 
 
 The veins terminate in the superior mesenteric and the splenic. The lymphatic vessels 
 are not well known ; it is probable that they enter the numerous glands which are in the 
 neighbourhood. The nerves of the pancreas are derived from the solar plexus. 
 
 The excretory duct {u,fig. 169) is called the canal of Wirsung, from the name of its dis- 
 coverer, a young anatomist, who was too soon lost to science. By an arrangement, of 
 which we have no other example in the body, this excretory duct is contained entirely 
 in the substance, we might even say, in the centre of the gland ; so that, in order to ex- 
 pose it, the superficial portion of the organ must be carefully divided. It is generally 
 single, but sometimes double, and then there is a principal duct belonging to the body of 
 the pancreas, and a small duct for the reflected portion, or lesser pancreas. The pan- 
 creatic duct measures the entire length of the gland ; it is narrow at the splenic extrem- 
 ity, which may be regarded as its origin, and gradually increases in size as it approach- 
 es the duodenal extremity ; there it bends downward, to reach the ductus choledochus, 
 to the left of which it is placed ; it runs along the side of that duct, then perforates it ob- 
 liquely, and opens, as I have already described when speaking of the liver, in the olive- 
 shaped ampulla immediately preceding the duodenal orifice of the ductus choledochus. 
 It follows, therefore, that the pancreatic duct and the ductus choledochus open by a com- 
 mon orifice in the human subject. This arrangement is constant, and, when we find a 
 pancreatic duct perforating the duodenum separately, we may be certain that there is 
 another duct presenting the regular arrangement ; at least, I have never observed to the 
 contrary. As to the precise situation of the separate opening of the supernumerary pan- 
 creatic duct, it may be either in front of, behind, below, or above, the orifice of the duc- 
 tus choledochus. Tiedemann, who has collected all the known cases of double pancre- 
 atic duct, and all the varieties of insertion found in the human subject, has arrived at the 
 curious result, that these varieties have their analogies in the different species of animals. 
 
 The mode in which the divisions of the pancreatic duct are inserted into the principal 
 trunk deserves to be noticed. The ultimate ducts of the pancreas do not, in fact, unite 
 into larger and larger branches, like the veins, but the small branches coming from each 
 lobule cpen directly, and in succession, into the general duct : an arrangement which 
 gives to the excretory apparatus of the pancreas the appearance of those insects called 
 centipedes. 
 
 As to the structure of the pancreatic duct, its walls are very thin ; it is collapsed, and 
 of a milk-white colour, very distinct from the grayish- white hue of the proper tissue of 
 the gland. Its internal surface is extremely smooth, like a serous membrane ; t its thin- 
 ness renders the determination of its texture very difficult ; it is very extensible. 
 
 Development. — The development of the pancreas presents no peculiarities excepting 
 such as relate to its size, which is relatively greater in the foetus and the new-born in- 
 fant than in the adult. Examples have occurred of disease of the pancreas during intra- 
 uterine life ; and I have found a scirrhous pancreas in a foetus at the full term. 
 
 Function. — The pancreas is the secreting organ of a particular fluid called the pancre- 
 atic fluid, the physical and chemical characters of which have not been well known until 
 very lately. I have met with two cases of retention of the pancreatic fluid. The dila- 
 ted canal resembled a transparent serous cyst ; the contained liquid was extremely vis- 
 cid and transparent, but of a whitish hue, like a solution of gum-arabic ; it had a slight- 
 ly saline taste ; the collateral ducts were extremely dilated. There were some white 
 patches, resembling plaster, in the centre of many of the lobules. This substance was 
 more abundant in some of the lobules, and, when removed, presented the appearance of 
 small lumps of plaster or chalk. The pancreatic fluid submitted to chemical analysis by 
 M. Barruel proved to be an extremely pure mucus. M. Barruel even stated to me that 
 it was the purest mucus he had ever examined. It possesses in the highest degree the 
 
 * [The only obsen'able difference between the lobules of the pancreas and salivary glands is, that the closed 
 tenninatiou of the ducts are cylindrical in the former, and slightly dilated in the latter (see note, p. 341).] 
 
 t lit is a mucous membrane, continuous with that of the duodenum, and covered with epithelium. In some 
 subjects, Mr. Kiernan found mucous follicles in it, similar to those in tlie biliary ducts ; in others, no traces of 
 them could be discovered. None were seen in the salivary ducts.] 
 
THE SPLEEN. 460 
 
 property of rendering water viscyi, either by dissolving, or by being diffused in it. This 
 mucus contains free soda, a trace of chloride of sodium, and a very slight trace of phos- 
 phate of lime. There is, therefore, an analogy belvi^een the pancreatic and salivary fluids, 
 as the anatomical investigation of these glands had previously led us to suppose.* 
 
 The Spleen. 
 
 The spleen {aizTiriv, lien ; k,fig. 154) is a spongy and vascular organ, the functions of 
 which, though little known, appear to be connected with those of the abdominal venous 
 system. 
 
 It is deeply situated {k,figs. 155, 161) in the left hypochondrium, behind and to the 
 left of the great end of the stomach, to which it is united by a fold of peritoneum, called 
 the gastro-splenic omentum. It is also retained in its place by the peritoneum, which is 
 reflected upon it from the diaphragm,! and by the vessels which enter and pass out from 
 it. Being suspended rather than fixed to certain movable parts, the spleen necessarily 
 participates in their movements ; and the contraction or relaxation of the diaphragm, as 
 well as the alternate distension and collapse of the stomach, exert an undoubted influ- 
 ence upon it ; but these slight and temporary changes of position do not constitute a 
 true displacement. 
 
 It may even be said that displacements of the spleen, which are very rare, are almost 
 always congenital. Thus, Haller has seen this organ situated at the left side of the 
 bladder, in an infant one year old ; Desault has found it in the right cavity of the thorax 
 in a foetus at the full time. I do not here allude to cases of complete transposition of 
 the viscera, nor to cases where the change of situation depends on enlargement of the 
 spleen, or on displacement of the stomach, t I have mentioned elsewhere that I have 
 found the spleen in the umbilical region. 
 
 Accidental adhesions of the spleen are so frequent that they deserve to be mentioned. 
 They are sometimes filamentous, and sometimes cellular, and they render painful the 
 slightest changes of position in this organ, from violent contractions of the diaphragm, 
 or from great distension of the stomach : these adhesions are almost always the sequelae 
 of intermittent fevers. 
 
 Number. — ^The spleen is single in the human subject. The supernumerary spleens oc- 
 casionally met with near it are nothing more than small ovoid or spheroidal fragments 
 of the spleen, which at first sight might be taken for lymphatic glands. I have never 
 seen more than two supernumerary spleens in man. It is said that they are more fre- 
 quent in the fcetus than in the adult : this opinion is erroneous. § It has been said that 
 ten, twelve, and even twenty-three supernumerary spleens have been observed. With- 
 out denying the possibility of the fact, I am inclined to doubt its occurrence. As the 
 spleen is always multiple in a great number of animals, supernumerary spleens in man 
 may be regarded as the last trace of such an arrangement. 
 
 With regard to the examples of congenital or accidental absence of the spleen men- 
 tioned by some authors, it should be remarked, that they were accompanied with se- 
 rious diseases of the abdomen, and that small adherent spleens, lost in some measure 
 among the surrounding organs, may easily have escaped notice in a not very close ex- 
 amination. 
 
 Size and Weight. — There is no organ which varies more than the spleen in regard to 
 size and weight. These differences may be referred to the following heads : 
 
 Individual Differences. — It is in vain to attempt to establish a relation between the 
 size of the spleen and that of the liver, or between the size of the spleen and the stature, 
 weight, constitution, and habits of the individual.il 
 
 Differences from Physiological Conditions. — The spleen is often found small, wrinkled, 
 shrunk, or, as it were, withered and collapsed ; a state that certainly supposes the op- 
 posite condition of distension. In other cases the spleen is large, and looks as if it 
 were stretched. Ought we, then, to admit, with Lieutaud,1F that the pressure from the 
 
 * [According to the best analyses, the pancreatic fluid differs from saliva in containinsr a greater amount 
 of solid matter, and also in the character of its constituents : saliva is usually alkaline, and, besides other sub- 
 stances, contains salivine, mucus, and sidpho-cyanate of potassa ; the pancreatic fluid contains albumen, ca- 
 sein, but little salivine and mucus, and no sulpho-cyanate ; in other respects the two fluids agree.] 
 
 t [This reflection is called the ligamentum phrenico-lienale. The spleen is also connected by the peritic 
 Ileum to the arch of the colon.] 
 
 i The great end of the stomach is the most fixed part of that viscus, on account of its connexion with the 
 CBSophagus. Changes of position in this organ affect partly the portion between the pylorus and the cardia, 
 and partly the pylorus itself. 
 
 () It is true that a greater number of cases of supernumerary spleens in the fcetus have been recorded than 
 in adults; but the fact is easily explained, if we consider that in the fcetus supernumerary spleens cannot 
 escape notice, while they are often diflicult to be seen in the adult, on account of the fat with whicli the 
 omenta are loaded. 
 
 II The spleen is proportionally larger in man than in the lower animals. It has been said, as if it were pos- 
 sible to establish a relation between two such variable terms as the weight of the spleen and the body, that 
 the former is i^^ th of the latter. 
 
 % Lieutaudasserts that he has constantly found the spleen larger when death has occurred while digestion 
 was going on in the stomach than when it has happened after that process had been completed ; but the 
 spleen varies so much in size that we cannot compare the spleen of one subject with that of another. An in- 
 genious experiment has been made, the re.sult of which is opposed to Lieutaud's opinion : out of four newly- 
 
404 SPLANCHNOLOGY. 
 
 distended state of the stomach during digestion diminishes the size of the spleen, which, 
 on the other hand, becomes the seat of an afflux of blood in the intervals between the 
 occurrence of that process. This idea is, perhaps, erroneous as far as regards the pe- 
 riods of collapse and turgescence ; but it is correct as to the principal fact, viz., the al- 
 ternation of those two opposite conditions. 
 
 Differences from Age. — The spleen is proportionally smaller in the foetus than in the 
 adult, and in the adult than in the aged. 
 
 Differetices from Disease. — The morbid differences in the size of the spleen suggest 
 most important considerations. In a great number of patients suffering with intermit 
 tent fevers, more especially when this organ is already enlarged from previous attacks, 
 it is manifestly swollen during each access. Hypertrophy of the spleen may proceed to 
 an extraordinary extent ; so that this organ, which, in the natural condition, is with- 
 drawn so deeply into the left hypochondrium as not to be seen on opening the abdomen, 
 in certain cases fills almost the whole of the abdominal cavity ; while its weight, which 
 varies from two to eight ounces in the healthy condition, may be as much as ten, twen- 
 ty, or thirty pounds ; one case, indeed, has been recorded where the spleen weighed 
 forty-three pounds. 
 
 Atrophy of the spleen is very rare. I have seen it reduced to the weight of two 
 drachms. 
 
 The specific gravity of the spleen is, to that of water, as 1160 to 1000. 
 
 The spleen, both upon the surface and in the interior, most commonly resembles in 
 colour the dark lees of wine. This colour, however, presents many varieties from a 
 deep-brown red to a pale gray. When the surface has been some time exposed to the 
 air, it becomes bright red, like the surface of venous blood soon after its abstraction. 
 Age, the kind of death, and diseases, have much effect on the colour of this organ, the 
 different parts of which are not always of a uniform tint. I have seen a spleen of a 
 deep chestnut-brown hue. 
 
 Consistence. — One character of the tissue of the spleen is its extreme friability. In 
 general it may be lacerated by the pressure of the finger, to which it communicates a 
 feeling of crepitation, and emits a sound like the crackling produced by bending tin. 
 The spleen may be regarded as the most friable of all organs excepting the brain. Thus, 
 examples have been recorded of its laceration from blows, or falls upon the abdomen, 
 and even from a general concussion, or from the contraction of the diaphragm and ab- 
 dominal muscles during violent exertion, &c. 
 
 The consistence of the spleen also varies much in different individuals, and in dis- 
 eases ; indeed, the most important alterations of this organ may be referred to either 
 increased or diminished consistence. In induration, which is generally accompanied 
 with hypertrophy, the tissue of the spleen is compact, brittle, and dry, and breaks like a 
 piece of compact resin. In softening, carried to its highest degree, the spleen is con- 
 verted into an inorganic pulp, exactly resembling a healthy spleen broken down by the 
 fingers, and containing a greater quantity of fluid than natural. This state is often ob- 
 served after malignant fevers,* and when the membranes are torn, the substance of the 
 spleen escapes spontaneously. 
 
 Figure. — The spleen has a crescentic form ; its long diameter is vertical, its concavity 
 directed to the right, and its convexity to the left side. It may be compared, as was 
 done by Haller, to a segment of an ellipse cut longitudinally. 
 
 It presents for consideration an external and an internal surface, and a circumference. 
 
 The external or costal surface is convex, smooth, and in relation with the diaphragm, 
 which separates it from the ninth, tenth, and eleventh ribs ;t hence arises the influence 
 of contractions of the diaphragm upon the spleen, and the possibility of its being rup- 
 tured during a violent effort. This relation also accounts for tlie pain felt in the region 
 of the spleen after quick running, and the difficulty and pain attendant on a strong inspi- 
 ration made while running by persons in whom the spleen is hypertrophied. 
 
 We frequently find a prolongation of the liver almost completely covering the external 
 surface of the spleen. 
 
 The internal or gastric surface is concave in all directions, and presents, at the junc- 
 tion of the two anterior thirds with the posterior, a somewhat irregular series of open- 
 ings, which are themselves irregular in form and number, are situated at greater or less 
 intervals, and arranged longitudinally. This row of openings is called XYve fissure, or hi- 
 lus {h,fig. 154) of the spleen. The gastro-splenic omentum is attached near this fissure. 
 Some varieties are observed in the arrangement of the internal surface of the spleen. 
 Thus, it sometimes presents a uniform concavity, and sometimes there is a sort of 
 projecting ridge opposite the hilus, which divides it into two unequal parts, one anterior 
 
 bom puppies, belonging to the same litter, two were kept witbout food, while to the other two milk was 
 given ; on killing them, their spleens were all found of the same size. 
 
 * Vide Anat. Path, avec Planches, liv. ii., art. Maladies de la Rate. I have been able to collect tho 
 splenic fluid in a medicine vial, and to submit it to different experiments. 
 
 t It is said that the ribs produce marks upon the spleen from the pressure exercised by them upon it during 
 life. 1 have never observed this appearance, and can only conceive it to exist in cases of hypertrophy of the 
 spleen. 
 
THE SPLEEN. 405 
 
 and larger, the other posterior and smaller : in the latter case, which is common, the 
 spleen is of a prismatic and triangular form. 
 
 The following are the relations of the internal surface : the part situated in front of 
 the hilus has relations with the great cul-de-sac of the stomach, and, on the right and 
 behind this cul-de-sac, with the gastro-splenic omentum and the vasa brevia situated 
 within it : the left extremity of the liver, which, as we have seen occasionally, covers 
 the external surface of the spleen, is more frequently in relation with the internal sur- 
 face of that organ. Behind the hilus the spleen corresponds with the left kidney, supra 
 renal capsule, and pillar of the diaphragm, which separate it from the spine, and with the 
 small extremity of the pancreas. 
 
 The circumferenc is elliptical ; its posterior border is thicker above than below, and is 
 in relation with the kidney, which it sometimes covers through its entire length ; its an- 
 terior border is thinner, and is applied to the stomach ; its upper extremity is thick, often 
 bent upon itself, and in contact with the diaphragm, from which, however, it is occasion- 
 ally separated by the liver ; its inferior extremity is pointed, and rests upon the angle 
 formed by the transverse and descending colon, or upon the portion of transverse meso- 
 colon which supports that angle. The circumference of the spleen is notched, and 
 sometimes marked more or less deeply by fissures, which are prolonged upon both its 
 surfaces, particularly upon the external surface, and which divide it into a greater or less 
 number of distinct lobules. This lobular arrangement is the last indication of the mul- 
 tiple spleens, of which we have already spoken. The description of the relations just 
 given applies when the stomach is empty ; when that viscus is distended, they are some- 
 what different. The spleen, which before was separated from the stomach by the gas- 
 tro-splenic omentum, is then applied directly to it, and is moulded upon it, so, as it were, 
 to cover its walls. It has no longer any relations with the kidney and the vertebral column, 
 but is situated below and behind the great cul-de-sac of the stomach, and not to the left 
 of it ; and it becomes horizontal instead of being vertical, as when the stomach is empty. 
 
 Structure. — Besides two investing membranes, one serous, the other fibrous,* the 
 spleen consists of cells having fibrous parietes, and filled with a grumous fluid,t of the 
 colour of port wine dregs, of certain corpuscules not very distinct in the hirnian subject, 
 of a very large artery and still larger vein, and of lymphatic vessels and nerves. 
 
 The serous or peritoneal coat invests the whole spleen, with the exception of the hilus, 
 which corresponds to the gastro-splenic omentum. It gives a smooth appearance to the 
 spleen, lubricates its surface, and, at the same time, fixes it to the neighbouring parts by 
 the bands which it forms. Its internal surface adheres closely to the fibrous membrane. 
 
 The proper coat of the spleen forms a sort of fibrous shell, which is strong, notwith- 
 standing its tenuity and transparency. This membrane is the seat of those cartilaginous 
 plates which are so often found upon its surface, and which conceal its true colour. It 
 is intimately united to the peritoneal membrane by its outer surface, and adheres still 
 more closely by its inner surface to the tissue of the spleen by means of exceedingly nu- 
 merous and dense fibrous prolongations, which penetrate it in all directions, and inter- 
 lace in every way, so as to form areolae or cells, the arrangement of which \fre shall here- 
 after examine. Farther, the proper coat is not perforated at the hilus for the passage of 
 the vessels, but by an arrangement similar to that already noticed in the liver, it is re- 
 flected around the vessels opposite the hilus, like the capsule of Glisson, and is prolong- 
 ed upon both the arteries and veins, forming sheaths which divide and subdivide like the 
 vessels themselves, and receive the prolongations given off" from the inner surface of the 
 proper coat. 
 
 This arrangement has been very well described by Delasonne {Mim. Acad, des Scien- 
 ces, 1754), and especially by Dupuytren (Thise de M. Assolant). It follows, therefore, 
 that the basis of the spleen is composed of a fibrous structure, consisting of an investing 
 fibrous membrane, of fibrous sheaths which accompany the vessels in their divisions and 
 subdivisions, even to their terminations, and of prolongations arising from the inner sur- 
 face of the membrane, interlacing in all directions, and attached to the outer surface of 
 the sheaths.J 
 
 The internal framework of the spleen is therefore an areolar tissue, which may be 
 very well displayed by washing away the pulpy matter of this viscus by means of a stream 
 of water ; there will then remain a whitish areolar and spongy tissue. This is also very 
 clearly shown by injecting it either with mercury or some coloured liquid, or even by in- 
 flating it with air blown through a puncture. The coats are then raised in different pla- 
 ces, and after desiccation, the areolar structure becomes evident. This experiment also 
 shows that the spleen is divided into a number of compartments, for, without rupture, 
 only a small portion of the organ can be injected in this way. 
 
 It appears, then, that the proper tissue of the spleen is composed of an areolar fibrous 
 
 * See note, infra. t See Bote, p. 406. 
 
 t [This basis or framework is more or less developed in the different species of animals : it is much stronger 
 in the horse than in the ox. The proper coat of the spleen, together with the sheaths for the vessels, and the 
 prolongations or trabcculae given off from it, are highly elastic, and are generally »tated to consist of yellow 
 elastic tissue, not of ordinary fibrous tissue.] 
 
^6 SPLAI^dHNOLOGY. 
 
 network, and of a pultaeeous matter, gf the colour of port wine lees — ^the splenic juice or 
 matter, regarded by the anciepts as one of the fundamental humours of the body, called 
 atra bills, and which modern Aemists have not yet sufficiently examined. 
 
 We have now to determine the arrangement of the cells, and the relation between 
 these cells and the arteries, veins, and nerves. 
 
 The Splenic Artery. — No organ of so small a size receives so large an artery. The 
 splenic artery is, in fact, the largest branch of the cceliac axis, and, on this account, rup- 
 tures or wounds of the spleen are almost always followed by fatal hemorrhage. It is 
 also remarkable for its tortuous course ; when reduced to half its original size, from hav- 
 ing given off several branches, it enters the spleen by four or five branches at greater or 
 less distances from each other. These branches divide in the usual manner in the sub- 
 stance of the organ, and preserve their tortuous character even to their terminations. 
 One peculiarity well worthy of attention is, that the arteries constantly divide in a ra- 
 diating manner, so that air, or water, or tallow, thrown into one arterial division, does 
 not pass into the branches of the others. This mode of division is observed not only in 
 the larger, but also in the smaller arteries,* so that the spleen may be considered as an 
 aggregate of a considerable number of small spleens, united together by a common in- 
 vestment ; and accordingly, if in a living animal one division of the splenic artery be tied, 
 the portion of the spleen to which it is distributed becomes blighted, while the rest re- 
 mains in the natural state. This arrangement of the arteries may be shown in a very 
 striking manner by injecting their several divisions with differently-coloured substances. 
 The injected matters will not mix, and the line of demarcation between the lobes will 
 become evident. 
 
 This structure explains how multiple spleens may occur in man and the lower animals, 
 and why there are so many varieties in this respect in the animal series. 
 
 Some branches from the splenic, lumbar, and spermatic arteries enter the spleen 
 through the folds of the peritoneum. 
 
 The splenic vein is four or five times larger than the artery : it forms one of the prin- 
 cipal roots of the vena portae, and is almost equal to the other root formed by the supe- 
 rior mesenteric vein. The venous communication between the spleen and the liver has, 
 in a great measure, given rise to the opinion that they are connected in function. The 
 spleen is filled by the numberless and large divisions of this vein ; it might even be said 
 that the texture of the spleen is essentially venous, that it is composed of a venous 
 plexus or an erectile tissue, and that it bears the same relation to the veins that the 
 lymphatic glands do to the lymphatic vessels. All the splenic cells communicate with 
 the veins, or, rather, they are nothing more than these veins themselves, supported by the 
 fibrous columns and sheaths already described : this is shown by the following consider- 
 ations and experiments : 
 
 1. If, according to the example of Delasonne,t we examine the spleen of the ox by lay- 
 ing open the splenic veins and their divisions by means of a grooved director, we shall 
 find that these veins are almost immediately reduced to their lining membrane, and per- 
 forated with very distinctly formed foramina, through which the dark reddish-brown sple- 
 nic matter is visible. These foramina soon become so numerous, that the veins are con- 
 verted into cavities or cells, the walls of which are perforated with openings of various 
 sizes, filled with the splenic pulp. This arrangement, which is most manifest under 
 water, proves that the tissue of the spleen is composed of venous cells,t like the corpo- 
 ra cavernosa of the penis. In man, the horse, and the dog, the great veins are not per- 
 forated with foramina, but the cellular and areolar arrangement of the splenic v^ins, at 
 a certain depth, is not less manifest. 
 
 2. If we inject the splenic artery, the spleen will become very slightly increased in 
 bulk at first, i. c, as long as the injected matter does not pass into the venous system ; 
 but as soon as this occurs, and it does so readily, the increase in size becomes rapid : it 
 follows, therefore, that the communication between the artery and the splenic cells is 
 indirect."^ On the other hand, if we inject the vein, the cells are immediately dilated, 
 and the spleen becomes prodigiously increased in bulk : it is easy to perceive that the 
 communication is direct, and that the venous system, in some measure, forms the basis 
 of this organ. 
 
 We can very seldom meet with a human spleen sufl5ciently healthy for the following 
 experiment. It will succeed perfectly with the spleen of a horse, which is of a much 
 denser structure. The spleen ought, in the first place, to be freed from the liquid which 
 it contains ; this must be accomplished by forcing water into the splenic artery. The 
 
 * [The minute arteries ramify in tufts orpenicilli.] 
 
 t Delasonne has described the structure of the spleen in the ox as belonging to the human subject. 
 
 t [According to Mr. Kiernan, these venous cells are lateral dilatations, which communicate with the venous 
 trunk by small branches. They contain only blood, however, for the red pulpy matter of the spleen is said by 
 Miiller to be external to, and not within them. This red substance consists principally of red granules, about 
 the size of the blood-globules, but spherical, not flattened.] ■ 
 
 t) It has been erroneously asserted that the communication between the artery and vein is more direct 
 in the .spleen than in any other organ. The great anastamoses, visible to the naked eye, between the splenic 
 artery and vein, admitted by Spigelius, Diemerbroeck, Bartholin, and others, are purely imaginary. The pre- 
 cise mode of communication is still unknown. 
 
THE SPLEEN. 407 
 
 water will return by the veins, at first turbid, then merely tinged, and at last limpid and 
 pure.* I have in vain attempted to force the injection from the veins into the arteries. 
 After the water, air should be blown into the artery, so as to empty the spleen as much 
 as possible of any liquid which it may contain. 
 
 If we examine a spleen thus freed of its contained matter, we observe that it is wrin- 
 kled, and, as it were, shrivelled on the surface, and remarkably diminished in bulk ; and, 
 on making a section of it, we find a white, spongy tissue, composed of laminae or fibres, 
 interlacing in every direction. 
 
 The following preparationt exhibits this structure most fully : The spleen of a horse, 
 prepared in the way I have indicated above, and weighing one pound, could receive ten 
 pounds of tallow. Tlie injection was thrown in by the veins : at each stroke of the pis- 
 ton, the spleen swelled up readily, an evident proof that the splenic cells communicate 
 directly with the veins ; while, in order to obtain the same effect by injecting through 
 the arteries, very considerable force was required. The injection of the spleen by the 
 veins did not take place in a uniform manner, but successively ; in one injection, the 
 upper part was injected before the lower, and the anterior border before the posterior. 
 The independence of different portions of the spleen on each other exists in regard to 
 their veins as well as their arteries. I have been enabled to observe the resistance of- 
 fered by the tissue of the spleen to the distending power ; a resistance which caused 
 the injection to flow back whenever the impelhng force was discontinued. The cells 
 are extensible to a certain degree, beyond which they resist very powerfully ; it does 
 not appear that they possess any elasticity.J 
 
 After some days, when desiccation was complete, the spleen thus injected was divided 
 into several portions, which were then immersed in spirits of turpentine moderately heat- 
 ed. The tallow, by which all the cells were distended, and which had taken the place 
 of their contents, having been dissolved out, the sections presented a spongy, areolar 
 structure, like that of erectile tissue, as found in the corpora cavernosa, or the substance 
 of the placenta : and this cannot be considered, as Meckel would have it, as the artificial 
 result of the insufflation and injection, which lacerate, as he believes, a part of the ves- 
 sels and fibrous tissue. — (Manuel d' Anatomic, t. iii., p. 479.) This spongy cellular struc- 
 ture explains why the spleen, as well as the corpora cavernosa, is susceptible of such 
 great variations in bulk ; and why it is sometimes found collapsed and wrinkled, and 
 sometimes distended, and, as it were, swollen. Are the splenic cells lined by the inter- 
 nal membrane of the veins T if so, the membrane is so thin as to be incapable of dem- 
 onstration. 
 
 Corpuscles of the Spleen. — Malpighi described, as existing in the spleen, certain cor- 
 puscles, regarded by him as the principal elements in this organ, and believed by him to 
 effect some important changes in the splenic bloodt These corpuscles, which Ruysch 
 considered to be essentially vascular, have been again brought into notice by Dela- 
 sonne, who demonstrated them by maceration. Haller denied their glandular nature, 
 because, as he said, there can be no glands where there is no secretion and no ex- 
 cretory ducts. The question is not, however, whether these corpuscles are glands or 
 not, but rather whether they exist at all. It is certain that, in many animals, in the dog 
 and the cat, for example, a great number of granules may be seen scattered through the 
 spleen, and which, according to a calculation, the accuracy of which I do not guarantee, 
 would seem to form two fifths of the weight of the organ. These corpuscles are soft, 
 whitish or reddish, and vary in diameter from a fourth of a line to a line. They do not 
 appear to me to exist in man.^ 
 
 The lymphatic vessels of t^e spleen are divided into the superficial and deep. The su- 
 perficial only are well known ; a certain number pass from the spleen to the stomach ; 
 they all terminate in lymphatic glands situated opposite the hilus, within the layers of 
 the gastro-splenic omentum. 
 
 * This injection, which requires considerable force, continued without interruption for a long time, occa- 
 sions an exudation of a perfectly transparent fluid upon the surface of the spleen, even when water returned 
 by the vein is stiU turbid. Here we have an imitation of an exhalant process. And, as this transudation takes 
 place without Tupture, it is evident that there are a set of vessels by which it is effected.* Instead of making 
 an injection, which is always troublesome, we may attach the splenic artery to a tube, which is itself adapted 
 to another tube, running from the bottom of a cistern ; the column of water will overcome the resistance offered 
 to its passage from the arteries into the veins, and in twenty-four hours it will pass through perfectly limpid. 
 
 t This mode of preparation was suggested to me by the plan adopted with the corpora cavernosa by Bogros, 
 prosector to the Faculty, who died a victim to his zeal for science. 
 
 t [The lining membrane of these venous cells is not veiy eitensible, but the trabecuUe, between which they 
 lie, are highly extensible and elastic also.] 
 
 ^ [The corpuscles here described are not those discovered by Malpighi, but large, soft, grayish bodies, rare- 
 ly found in the human spleen, and the nature of which is not understood. The Malpighian corpuscles are 
 much smaller ; they are very evident in the ox, sheep, and pig ; they lie in the red pulpy matter externally 
 to the venous cells, and are attached by short pedicles, or without pedicles, to the minute arteries, which, 
 however, have not otherwise any special relation to them ; they contain grayish granules, similar in size and 
 form to those of the red pulpy matter. In the human spleen they are very difficult to distinguish. 
 
 The extremities of the divided trabeculse may be mistaken for white corpuscles.] 
 
 *■ [This transudation evidently depends on the porosity or permeability of animal tissues, and not on the ex- 
 istence of any special vessels.] 
 
408 SPLANCHNOLOGY. 
 
 Nerves. — The nerves are derived from the solar plexus, and are termed the splenic 
 plexus. It has been stated that some terminal divisions of the pneumogastric have been 
 seen distributed upon the spleen. Several of the nerves are remarkable for their size, 
 which enables us to examine in them the peculiar structure of the ganglionic nerves, 
 and also to trace the splenic nerves themselves deeply into the substance of the organ.* 
 We are completely ignorant of their mode of termination. 
 
 As to the proper ducts of the spleen, said to pass directly from that organ to the great 
 cul-de-sac of the stomach, or even to the duodenum, and to pour into these parts a pecu- 
 liar liquid, it may be confidently stated that they are purely imaginary. And again, the 
 three kinds of vascular conununication between the spleen and the stomach cannot in 
 any way explain the afflux of liquids from the spleen to the stomach ; in fact, the arte- 
 rial vasa brevia of the stomach are given off from the splenic artery before it reaches 
 the spleen ; nor do the venous vasa brevia enter the splenic vein until after it has left 
 the hilus of the spleen ; the lymphatic vessels alone pass directly from the spleen to the 
 stomach, but they are superficial, and have no connexion with the splenic cells. 
 
 There is no cellular tissue, properly so called, in the spleen, which, nevertheless, is 
 liable to inflammation. 
 
 Development. — In opposition to the liver, the spleen is smaller in proportion as it is ex- 
 amined nearer the period of conception. It appears late ; it begins to be distinguisha- 
 ble towards the end of the second month, and it then resembles a clot of blood. I hav^e 
 never seen it developed from separate lobules, which were afterward to be united by a 
 common investment. At birth, its proportions are almost the same as at subsequent pe- 
 riods. The spleen is hard, and, as it were, tense, in most infants who die during birth : 
 this is probably owing to impeded circulation. 
 
 The changes which the spleen undergoes during growth, both in density and in size, are 
 partly physiological, which are not very remarkable, and partly pathological ; these are very 
 considerable, but they are foreign to my subject. In the aged, the spleen decreases, like 
 all other organs ; and atrophy of this organ, which may proceed so far that it only weighs 
 a few drachms, is often accompanied by the development of a cartilaginous shell. 
 
 Functions. — The functions of the spleen appear to me to be referrible to its structure 
 and its vascular connexions. The quantity of blood which passes through it, its entire- 
 ly vascular structure, and the physical qualities of the splenic pulp prove, on the one 
 hand, that the blood sent to the spleen serves other purposes besides that of nutrition ; 
 and, on the other, that it undergoes some important changes, of which we are complete- 
 ly ignorant, because the means of analysis are wanting ; but, whatever they may be, they 
 have undoubtedly some connexion with the functions of the liver, t for in all animals 
 possessing a spleen, even though its arterial blood does not come to it from the same 
 trunk as the hepatic artery, the veins of the spleen terminate in the venous system of 
 the liver. It is, therefore, extremely probable that the spleen performs an important 
 office in the abdominal venous system ; but what this office is we do not know ; and 
 what tends to confound all our calculations is, that extirpation of this organ in animals 
 does not seem to have any marked effect upon their health, that the most complete atro- 
 phy of the spleen is consistent with the most regular performance of all the functions, 
 and that hypertrophy, even to such a degree that the organ occupies almost the whole 
 of the abdomen, merely produces a discoloration of the skin, diminished nutrition, and, 
 in young subjects, an arrest of growth. 
 
 The spongy and vascular texture of the spleen, and the absence of valves, which al- 
 lows the venous blood to regurgitate into the spleen when there is any obstacle to the 
 circulation, has led to the opinion that the spleen is nothing more than a diverticulum 
 intended to restore the equilibrium of the abdominal venous system whenever it is de- 
 ranged ; and this opinion, which we owe to Haller, is pretty generally admitted.^ A 
 modification of this opinion is, that the spleen fulfils, with regard to the circulation in 
 general, and especially to the abdominal circulation, the office of the safety-tube of Wolf 
 in chemical apparatus. It is certain that compression of the splenic vein in a living an- 
 imal causes tumefaction of the spleen, which gives place to a quick collapse, as if by 
 elastic contraction, when the pressure on the vein is removed : it is certain that the 
 whole structure of the spleen indicates that this organ may undergo alterations of ex- 
 pansion and turgescence, and of collapse and flaccidity ; and it is known that, during in- 
 termittent fever, the spleen may be felt below the false ribs, &c. But all this leads to 
 presumptions, and not to certainty. 
 
 From the preceding considerations, it would follow that the spleen is only an accesso- 
 ry organ. 
 
 * The sensibility of the spleen is very important. In a living animal it may be cat or torn without an> 
 apparent signs of pain. Dogs have been seen devouring their own spleens, which had been drawn out of the 
 abdomen'. What a diiference, in this respect, between the spleen and the intestine! and yet they derive 
 their nerves from the same source. 
 
 t We cannot state, with Malpighi, that the spleen is the preparatory organ of the bile, because we have 
 seen that it is extremely probable that the liver is concerned in the process of sanguification. 
 
 t May we not quote, in support of tliis view, the pain felt in the region of the spleen after violent running, 
 which can only be referred to extreme di&teusiou of this organ ' 
 
THE LUNGS. 40& 
 
 THE ORGANS OF RESPIRATION. 
 
 General Observations. — The Lungs and Pleura. — The Trachea and Bronchi. — Development 
 of the Lungs. — The Larynx — its Structure, Development, and Functions. — The Thyroid 
 Gland. 
 
 After describing the digestive apparatus, the object of which is to elaborate soHd and 
 liquid materials for the reparation of the waste that occurs in the body, and, at the same 
 time, to present a vast surface for the absorption of those materials, we naturally turn 
 to the consideration of the apparatus of respiration, the object of which is to renew the 
 Tital properties of the blood by the action of atmospheric air in the lungs. 
 
 This latter apparatus, whicli is much less complex than the former, is composed, 1. Of 
 the lungs, the essential organs of respiration ; 2. Of the thorax, a cavity forming a sort 
 of bellows, and having walls capable of alternately expanding and contracting ; 3. Of a 
 tubular apparatus, by which the lungs communicate with the external air, and which 
 consists of the bronchi, trachea, larynx, pharynx, and nasal fossce; for it is only accidental- 
 ly, so to speak, and in order to render respiration more certain, that air is allowed to 
 pass through the mouth. 
 
 The thorax has been already described (see Osteologt and Myology), and also the 
 pharynx, which is common to both the respiratory and digestive passages. 
 
 The nasal fossae, situated at the entrance of the respiratory passages, form the natu- 
 ral passages for the introduction of the air, and, at the same time, serve for the reception 
 of the organ of smell, by which sense we may consider the qualities of the air are exam- 
 ined. Their bony framework has been already described under osteology. The pitui- 
 tary membrane which covers the irregular surfaces of these fossae will be described in 
 the article devoted to the organs of the senses ; we shall only consider, in this place, 
 the lungs, the trachea, and the larynx. 
 
 The Lungs. 
 
 The lungs (pulmoncs ; mevfiuv, from Trviu, to breathe, p p,figs. 155, 170, 171) are the 
 essential organs of respiration. While the presence of an alimentary canal is the attri- 
 bute of all animals, that of lungs is limited to those vertebrata which live in the air, dif- 
 ferent modes of respiration prevailing in the other classes. 
 
 Number. — The lungs are two in number ; but, as the air which penetrates them is re- 
 ceived from one tube, and the blood circulating through them is derived from one vascu- 
 lar trunk, they must be regarded as separated parts of a single organ ; by this arrange- 
 ment, respiration is rendered certain, and its unity maintained. 
 
 Situation. — The lungs are situated {p p, fig. 155) in the thoracic cavity, which is, in a 
 great measure, occupied by them, and effectually protects them from the action of exter- 
 nal agents ; they are placed on each side of the heart {h,figs. 155, 170, 171), with which, 
 physiologically, they are so directly connected ; they are separated from each other by 
 the mediastinum (m) ; hence the independence of the two cavities in which they are 
 contained. Being separated by the diaphragm from the stomach, the liver, and all the 
 other abdominal organs, they are so enclosed in all directions as not to be liable to dis- 
 placements, or, rather, such displacements are only partial, and due to a loss of substance 
 in the walls of the cavity in which they are placed. 
 
 Size. — The size of the lungs necessarily corresponds exactly with the capacity of the 
 thorax, and therefore, like it, is subject to variations ; and as, on the one hand, the size 
 of the lung is generally a measure of the energy of respiration, and, on the other, the en 
 ergy of respiration is a measure of the muscular strength, one cannot be astonished that 
 a capacious chest, coinciding with broad shoulders, should be the characteristic of a san- 
 guine temperament and athletic constitution. 
 
 In the natural state there is neither air nor watery fluid between the parietes of the 
 thorsix and the surface of the lung. The absence of air or other fluid may be shown af 
 ter death as well as upon a Uving animal, by raising the inter-costal muscle from the 
 costal pleura, so as to preserve the latter,* or by removing the muscular fibres of the dia- 
 phragm. It is then seen that the lung is always in contact with the parietes of the chest ; 
 in some subjects it even appears as if ready to escape ; but scarcely is the thorax opened 
 when the lungs instantaneously collapse, in consequence of the expulsion of the air from 
 their interior. It is very common to find a small quantity of serum in the cavity of the 
 pleura, but it is probable that this fluid did not exist during life. There is no space to 
 be filled up here as in the cranium. 
 
 The differences in the size of the lungs depend, 1. On the state of inspiration or expi- 
 ration. Attempts have been made to determine the difference from this cause by esti- 
 mating the volume of air inspired or expired ; it is about thirty cubic inches, and may be 
 increased to forty in forced inspiration or expiration. 2. On age ; thus, in the foetus, the 
 lungs are relatively much smaller than after birth. 3. On some morbid condition. The 
 
 * In order to demonstrate the absence of air, we may also repeat another experiment performed by Haller, 
 ■which consists in opening the thorax of a dead body under water. 
 
 F F F 
 
410 SPLANCHNOLOGY. 
 
 lungs diminish in size when the abdominal viscera encroach upon the thorax, either m 
 ascites, in pregnancy, or in diseases of the liver, vv'hich organ has been found in some 
 cases to become enlarged entirely by encroaching on the chest, and to extend as high 
 up as the second rib. They diminish, also, when the heart is enlarged in aneurism, or 
 when a large quantity of fluid is accumulated in the pericardium. In effusions into the 
 thorax, the fluid takes the place of the lung ; the latter gradually wastes, and is reduced 
 to such a thin lamina, or to so small a mass, that it has sometimes been overlooked in 
 a superficial examination ; but if, in such cases, air be blown into the trachea, the organ 
 appears of its full size, and gradually fills the remainder of the cavity. This extreme 
 diminution of the lung, without any alteration of its substance, proves that the size of the 
 organ is essentially dependant upon the air within it. Attempts have been made to cal- 
 culate exactly the quantity of air contained in the cavity of the lungs, or, in other words, 
 the capacity of these organs : according to one estimate, which can only be regarded as 
 an approximation to the truth, it would seem to be about 1 10 cubic inches after expira- 
 tion, and 140 inches after an ordinary inspiration. 
 
 When an effusion in the thorax has been very slowly absorbed, the lung of the affect- 
 ed side remains atrophied, and the thoracic cavity contracted, while the other lung ac- 
 quires a very considerable size, so that the mediastinum is pushed to one side, and the 
 healthy lung passes beyond the median line.* In certain cases of acute pneumonia, and 
 in rickets affecting the thorax, we often see one of the lungs reduced to very small di- 
 mensions, whUe the other is very much enlarged.! 
 
 The size of the two lungs is not absolutely the same. In consequence of the heart 
 projecting into the left cavity of the thorax, the transverse diameter of the left lung is 
 not equal to that of the right ; and on account of the projection of the liver into the right 
 cavity, the vertical diameter of the right lung is less than that of the left. After edlow- 
 ing for these facts, the difference is in favour of the right lung. In determining the size 
 of the lungs, we must bear in mind, that the lung eis well as the thoracic cavity gains in 
 one direction what it loses in another : elongated lungs, which are regarded as particu- 
 larly liable to phthisis, have not seemed to me to be smaller than the lungs of a person 
 of similar stature, but having a broad chest. 
 
 The weight of the lungs must be examined with reference to their specific gravity and 
 to their absolute weight. The specific gravity of the lungs is less than that of any other 
 organ, and even much less than that of water. Their lightness depends on the great 
 quantity of air which penetrates them in every direction, so that the lungs rise to the 
 surface of the fluid in which they are immersed. The specific gravity of the lungs pre- 
 sents some important differences depending on age. Thus, before birth, and in an in- 
 fant that has died during birth, without having respired, the lungs sink in water ; on the 
 contrary, they swim when the infant has breathed ; not because any change has taken 
 place in the intrinsic nature of the organ, but because the air has insinuated itself into 
 the cells. The estimation of the specific weight of the lungs constitutes what is called 
 in legal medicine the hydrostatic test. In the adult, the lung always floats, notwithstand- 
 ing any efforts which may be made to expel the air contained in the pulmonary cells ; it 
 seems as if the air enters in some way into the composition of the lung, and even in 
 vacuo it cannot be completely extracted. The specific gravity of the lungs varies also 
 from disease. Thus, lungs infiltrated with serum, or indurated by inflammation, being 
 completely or partially deprived of air, on the presence of which their lightness depends, 
 assume, in a greater or less degree, the appearance of compact organs, such as the liver 
 or the spleen. 
 
 The absolute weight of the lung varies from similar causes. From age : thus, although 
 the specific gravity of the foetal lung is much greater than that of the adult, yet its abso- 
 lute weight is considerably less. In infants that have not breathed, the weight of the 
 body is to that of the lungs as 60 to 1, on an average, while in those that have breathed 
 the proportion is as 30 to 1, so that the changes in the lungs resulting from respiration 
 are such as to double their weight. We may easily conceive the great importance of 
 this fact in legal medicine. This method of estimating the weight of the lungs is known 
 by the name of the static test. 
 
 The absolute weight of the lungs varies much in disease. Healthy lungs are very 
 light ; diseased lungs may become eight or ten times heavier than natural, without in- 
 creasing in size. The lungs ahnost always becoming engorged at their posterior bor- 
 der during the last moments of life, their weight must not be estimated from an ordinary 
 corpse. It must undoubtedly have been from the examination of engorged lungs that 
 authors have stated their average weight to be four pounds. 
 
 Colour. — The colour of the lungs varies according to age and disease. In the fcetus 
 they are reddish-brown ; after birth, rosy-white ; in the adult and in the aged they are 
 
 * In a case of chronic induration of the left lung, the deviation of the mediastinum was so great, that the 
 nght lung was in relation with the left costal cartilages. 
 
 t The lungs become less increased in size from inflammation than most other organs ; and this peculiarity 
 is explained by the vesicular structure of the lung, the increase in size being effected at the exp«ase of the 
 cavity of the air-vesicles. 
 
♦ffiE LUNGS. 411 
 
 gra>\sh-blue, and almost always marked by black spots, forming points, lines, or patches, 
 and describing polygons more or less regular in figure. These black patches, which be- 
 come much more numerous in advanced age, coexist with the black deposites in the 
 bronchial glands, and probably depend upon the same cause ; they lie below the serous 
 covering of the lungs, and are very superficial, excepting in disease. The posterior part 
 of the lung is usually of a reddish-brown colour, because it is distended with blood and 
 serum. It has not been shown that this is altogether a post mortem condition, and the 
 necessary consequence of the position of the corpse upon its back ; many facts woidd, 
 on the contrary, induce us to admit that it occurs antecedently to death. 
 
 Density, Crepitation, and Cohesion. — The lung, a spongy or aerial organ, so to speak, 
 is the least dense of all the organs in the body ; it yields to the pressure of the hand, 
 and, if no cause prevents the escape of the air, it loses very much of its original size. 
 I have remarked, when speaking of the spleen, that, under pressure, that organ emitted 
 a peculiar noise, or, rather, gave rise to a sensation which might be compared to the 
 crackling of tin, and that this sound was the result of rupture of the fibrous prolongations 
 which traverse its tissue. Pressure of the lung causes a sensation and a sound some- 
 what analogous to the preceding ; this sound is called crepitation. It may, in fact, be 
 compared to the sound produced by the decrepitation of salt or the rattling of paper. 
 This crepitation is only observed under a moderate pressure, and if the sensation com- 
 municated be strictly noted, we shall find that it is the feeling of a resistance overcome. 
 On careful examination of the portion of the lung which has thus crepitated, bubbles of 
 air are found under the pleura ; in fact, emphysema is produced. Notwithstanding its 
 slight density, the tissue of the lungs possesses tolerable strength ; it resists laceration 
 to a certain point ; and all its parts are pretty firmly bound together. 
 
 Resistance to Distension. — The lung, though it yields to the finger without recovering 
 itself at all, or only very imperfectly, is yet possessed of great elasticity, but such an 
 elasticity as is in harmony with its functions. It also offers powerful resistance to any 
 distending force. Thus, if a stopcock be adapted to the trachea of a dead body, and the 
 lungs be inflated by means of bellows having double valves, the pulmonary tissue becomes 
 extremely tense and hard ; the effort necessary to rupture some of the air-cells, and pro- 
 duce emphysema, is surprising. In opposition to those authors who speak of the dan- 
 gers of artificial insufflation of the lungs of asphyxiated persons, I have in vain endeav- 
 oured, with aU the force I could employ in expiration, to produce a laceration of some of 
 the pulmonary cells : and how, it may be asked, without great means of opposing every 
 attempt to dilate them beyond measure, could the lungs resist the force to which they 
 are subjected during violent exertions 1 
 
 Elasticity. — The lungs are very elastic, i. e., they have a constant tendency to tol- 
 lapse, and to free themselves of part of the air contained in their cells. It is this elasti- 
 city which maintains the vaulted form of the diaphragm after the abdomen has been 
 opened, and occasions the lung to collapse suddenly, when an opening is made in 
 the parietes of the thorax : before the chest is opened, the atmospheric pressure, opera- 
 ting through the trachea, prevents the elasticity of the lungs from being brought into ac- 
 tion. * This elasticity is also shown by the quick collapse of inflated lungs. I have been 
 accustomed to demonstrate, in my lectures, perfectly healthy lungs, preserved in alco- 
 hol. After having shown how far the inflation of the lungs may be carried, I open the 
 stopcock used in the experiment, and the lungs instantly collapse, driving out the air 
 with considerable force. 
 
 Shape and Relations. — The lungs are shaped like an irregular cone, deeply excavated 
 on the inner side, with the base below and the apex above ; they present for consideration 
 an external and an internal surface, an anterior and a posterior border, a base, and an apex. 
 
 Outer or Costal Surface. — This surface is irregularly convex, corresponding to the con- 
 cavity of the thoracic parietes, with which it is in contact, and on which it is exactly 
 moulded ; it is in relation with the costal pleura, which separates it from the ribs and 
 the intercostal muscles. It presents a deep fissure, the inter-lobular fissure, which pen- 
 etrates the entire thickness of the lung as far as the root. This fissure conunences be- 
 low the apex of the lung {v',Jig. 171), passes downward and forward {v',fig. 170) as fair 
 as the anterior part of the base, upon which it encroaches a little at its termination. It 
 is simple in the left lung («'), but is bifurcated in front in the right ; the lower division 
 of this bifurcation continues in the original direction ; the upper division (ic) passes up- 
 ward and forward. The left lung, therefore, is divided into two portions or lobes, dis- 
 tinguished as the superior («') and the inferior {u') ; while the right is divided into three 
 lohes, the superior (s), the inferior (m), and the middle {t). Of these lobes, the inferior, 
 comprising the base of the lung, is larger than the superior, which forms the apex ; the 
 middle lobe is the smallest. Tlie contiguous surfaces of these lobes are plane, and cov- 
 ered by the pleura : they are often Eidherent, and sometimes purulent matter collects be- 
 
 * [The longs Jo not collapse nntil the chest is opened, because the atmospheric pressure is exerted only on 
 the inner surface of the lungs, their outer surface being- protected from it by the unyielding parietes of the 
 thorax. When this protection is removed, the pressure on both surfaces is equal, and the elasticity of the 
 pulmonary tissue is tlien enabled to act.] 
 
412 
 
 SPLANCHNOLOGY. 
 
 Fig. 170. tween them, and, being sm- 
 
 rounded on all sides by adhe- 
 sions, it hollows out, as it 
 were, a cavity for itself, at the 
 expense of the corresponding 
 surfaces of the lobes, and thus 
 simulates an abscess of the 
 lung. 
 
 There are many varieties 
 in the arrangement of these 
 lobes. Thus, sometimes, the 
 fissures, and more especially 
 those which bound the middle 
 lobe, do not reach as far as 
 the root of the lungs, but are 
 only slightly indicated. Three 
 lobes are not unfrequently 
 found in the left lung, or four 
 in the right ; there were four 
 lobes in the lung of a negro 
 lately presented to the ana- 
 tomical society. 
 
 Examples are on record of 
 lungs with five, six, and even 
 seven lobes, but in general this 
 multiplicity of lobes is only 
 rudimentary, and represents 
 the normal condition in the 
 majority of animals. The dog, 
 the sheep, and the ox have 
 seven lobes in their lungs 
 Inner or Mediastinal Surface. — This corresponds to the mediastinum (p p). On it we 
 observe the root (r) of the lungs, that is, the part at which they communicate with the 
 trachea, through the bronchi, and receive and emit their bloodvessels. This root oc- 
 cupies a very limited space upon the inner surface, one inch in height, and half an inch 
 in breadth ; it is situated at the junction of the posterior with the two anterior thirds of 
 this surface, at an almost equal distance from the apex and the base. 
 
 That part of the inner surface of the Jung which is behind the root corresponds to the 
 vertebral column and the posterior mediastinum, in which are found, on the left side, the 
 descending aorta and the upper part of the thoracic duct ; and on the right side, the vena 
 azygos, the oesophagus, and the lower part of tlie thoracic duct. 
 
 All that portion of the inner surface which is in front of the root corresponds with 
 the anterior mediastinum, and is excavated to receive the heart (l) ; and as the heart 
 projects more to the left than to the right side, it follows that the left lung, which cor- 
 responds to the left border and apex of the heart, and higher up to the arch of the aorta 
 ig), is more deeply excavated than the right lung, which corresponds to the right auricle 
 (m) and the vena cava superior {see Jig. 170). We can obtain an accurate idea of the 
 manner in which the lungs are excavated for the reception of the heart only by ex- 
 amining them when inflated ; we are then struck with the propriety of the expression of 
 Avicenna, who called the lung the bed of the heart. We can also understand how diseases 
 accompanied with enlargement of the heart may directly influence the respiration, by 
 reducing the size of the lungs. These organs, it may be remarked, are here in apposi- 
 tion with the heart through the medium of the pericardium and the pleura. I should not 
 omit to mention their relation with the phrenic nerve, which is affixed closely to the 
 pericardium by the pleura. In the foetus, the lungs are in relation anteriorly with the 
 thjTnus gland, which presses them backward. 
 
 The anterior border is thin and sinuous, presenting on the left side two notches, one 
 inferior and very large, corresponding to the apex of the heart ; the other superior and 
 small, for the subclavian artery. On the right side there are also two notches, but 
 smaller than those on the left ; an inferior for the right auricle, and a superior for the 
 vena cava superior. 
 
 The posterior border (fig. 171) is the thickest part of the lung. It fills the deep costo- 
 vertebral groove situated at each side of the dorsal portion of the spine. 
 
 The base is concave, and exactly moulded upon the convexity of the diaphragm (x, 
 fig. 170); it is, therefore, a little more excavated on the right than on the left side. 
 Its circumference is very thin, and slightly sinuous. Like the diaphragm, the base of 
 the lung forms an inclined plane from before backward and downward ; and it occupies 
 the deep angular groove formed behind, between the diaphragm and the parietes of the 
 thorax. On account of this obliquity of its base, the vertical diameter of the lung is much 
 
THE LUNGS. 413 
 
 greater behind than in front ; and as the posteiior border is the largest part of the organ, 
 it may be conceived that an examination of the lung should be directed chiefly to this 
 part. It is of importance to form a correct idea of the manner in which the base of the 
 right lung and the convexity of the hver are arranged with regard to each other. The 
 liver is, as it were, received into the concavity of the base of the lung so completely, that 
 the posterior part of this base is almost on a level with the lower surface of the liver. 
 The relation of the hver with the base of the lung, which is only separated from it by the 
 diaphragm, explains how abscesses and cysts of the liver may Jjurst into the lung. 
 
 The apex is obtuse, and projects above the first rib, a very strongly-marked impression 
 of which is found on its anterior surface. I have observed that the height of the portion 
 which passes above the first rib varies in different subjects. In severed I found it from 
 an inch to an inch and a half In an aged female, in whom the base of the thorax was 
 extremely constricted, the apex of the lung (i. e., the part bounded below by the depres- 
 sion corresponding to the first rib) was two inches in height. May not the mechanical 
 pressure of the inner edge of the first rib upon the apex of the lung exercise some influ- 
 ence in the very frequent development of tubercles in that region 1 In order to form a 
 correct idea of the apex of the lung, that organ must be previously inflated. 
 
 The whole surface of the lung is free, smooth, and moistened with serum ; it is con- 
 nected with the rest of the body only by its root, which attaches it to the bronchi and the 
 heart, and by a fold of the pleura. It is very rare to meet with lungs free from adhe- 
 sions upon their surface, so that the older anatomists regarded these adhesions, whether 
 filamentous or otherwise, as natural formations. 
 
 Structure of the Lungs. 
 
 On examining the structure of the lungs, we find in each an investing membrane oi 
 serous sac, formed by the pleura, and a proper tissue. We shall conmxence with the 
 pleiira. 
 
 The Pleura. 
 
 Dissection. — In order to obtain a view of the costal pleura, saw through the six or 
 seven upper ribs behind, near their angles ; cut through the cartilages of the same ribs, 
 at a distance of some lines from their sternal articulations ; remove the intermediate 
 portions of ribs and intercostal muscles with great care, so as to leave the costal pleura 
 imtouched. The cavity of the pleura may be inflated. 
 
 In order to see the mediastinal and pulmonary portions, the costal pleura must be 
 opened, and its continuity traced. 
 
 The -pleura {nXevpu, the side) is a serous membrane, and, therefore, a shut sac, which 
 is extended partly over the parietes of the thorax, and partly over the lungs. There are 
 two pleurae, one for the right and the other for the left lung. The following is their gen- 
 eral arrangement : 
 
 The pleura lines the parietes of the thorax, the ribs, and the diaphragm, forming the 
 pleura costalis (p p,fig. 151) and pleura diaphragmatica ; it invests the entire surface of 
 the lung, constituting a sort of integument for it, and forming the pleura pulmonalis ; 
 lastly, it is applied to the pleura of the opposite side, so as to form a septum between 
 the two lungs ; this part is the mediastinal pleura. 
 
 In order to facilitate the description of the pleura, we shall suppose it to commence 
 at a certain point ; and then, following its course without interruption, shaU trace it 
 back to the point from which we started. If we thus commence at the sternum, we 
 shall find that it lines the internal surface of the thorax, being apphed to the ribs and 
 the intercostal muscles, and covering the mammary vessels and lymphatic glands in 
 front, the intercostal vessels and nerves behind, and the ganglia of the great sympa- 
 thetic opposite the heads of the ribs : below, it is reflected upon the diaphragm, and 
 covers the whole of its upper surface : above, it is reflected beneath the first rib, and 
 terminates in a cul-de-sao, intended for the reception of the apex of the lung, and pro- 
 jecting more or less above that rib. 
 
 Having reached the sides of the vertebral column, the two pleurae are reflected for- 
 ward as far as the root of the corresponding lung, and form, by their approximation, a 
 septum, which is called the posterior mediastinum. This septum contains within it the 
 aorta, the oesophagus, the pneumogastric nerves, the thoracic duct, the vena azygos, a 
 considerable quantity of cellular tissue, a great number of lymphatic glands, and the 
 trachea. We see, then, that the two pleurae are by no means in immediate contact. 
 
 Arrested, as it were, by the root of the lungs, the pleura is reflected outward behind 
 that pedicle, passes over a small portion of the pericardium, covers all that part of the 
 inner surface of the lungs which is behind its root, and also its posterior border and its 
 outer surface, dips into the inter-lobular fissure, so as completely to invest the contigu- 
 ous surfaces of the lobes, is reflected over their anterior margin upon their inner surface, 
 reaches the root of the lung, and covers its anterior surface, is then reflected forward 
 upon the side of the oericardium, in front of which it is applied to the pleura of the op- 
 
414 SPLANCHNOLOGY. 
 
 posite side, and at length arrives at the border of the sternum, from which we had sup- 
 posed it to commence.* 
 
 The antero-posterior septum formed by the two plurae, between the sternum and the 
 root of the lung, is called the anterior mediastinum {m,fig. 155).t This septum is not 
 vertical nor median, Uke the posterior mediastinum, but is directed downward and to 
 the left side, an arrangement that is connected with the oblique position of the heart, 
 which encroaches more upon the left than the right cavity of the thorax. It follows, 
 from this, that the uppej part of the anterior mediastinum {p p,fig. 170) is behind the 
 sternum, while its lower portion is behind the left costal cartilages, and hence the in- 
 terior of this mediastinum may be reached without opening the cavity of the pleura, by 
 Introducing an instrument close to the left border of the sternum, opposite the fifth rib. 
 The anterior mediastinum is narrow in the middle, and expanded above and below, Uke 
 an hour-glass. The upper cone or expansion is very much developed in the fcetus, and 
 Is occupied by the thymus gland, which is afterward replaced by cellular tissue : the 
 lower cone or expansion is much larger, and contains the heart and pericardium, the 
 phrenic nerves, and in front of the heart a large quantity of cellular tissue. 
 
 This latter, which is so abundant in the anterior mediastinum, communicates freely 
 above with the cellular tissue in front of the neck, and below with that of the abdominal 
 parietes, through a triangular interval existing in the diaphragm behind the sternum. 
 
 This double communication explams how the pus of an abscess formed in the neck 
 or in the mediastinum may reach the surface in the epigastric region. 
 
 The pleura has two surfaces, one an external, the other internal. 
 
 External or Adherent Surface. — ^This does not adhere with equal firmness to all the 
 parts which it covers. The pleura costalis is but slightly adherent, and may be separa- 
 ted from the ribs and the intercostal muscles with the greatest ease. It is sometimes 
 raised in the situation of these muscles by subjacent adipose tissue. It is strengthened 
 by a layer of fibrous tissue, which, notwithstanding its tenuity, performs an important 
 part in diseases of the chest ; it explains why abscesses formed in the parietes of the 
 thorax so seldom open into the cavity of the pleura, and why effusions into the pleura 
 are so rarely discharged externally. The diaphragmatic pleura is more adherent than 
 the costal. We sometimes find here, especially round the pericardium, some large fat- 
 ty appendages, resembling the appendices epiploicae of the great intestine. The pleura 
 is extremely thin upon the lungs {pleura pulmonalis), where it is not strengthened by 
 any fibrous tissue ; and although it is more adherent here than the parietal pleura, still 
 it can be easily demonstrated. The mediastinal pleura is united to the parts contained 
 within the mediastinum by very loose cellular tissue, but it adheres more firmly to the 
 Bides of the pericardium, to which the phrenic nerves are closely applied. 
 
 The internal or free surface is smooth,t moistened with serum, and in contact with 
 itself throughout its entire extent, as is the case in all serous membranes. The adhe- 
 sions so commonly met with here are altogether accidental. The structure of the pleura 
 is cellular.^ It is doubtful whether it receives any arteries and veins. The vascular 
 network, which is sometimes so highly developed after pleurisy, does not belong to it, 
 but is situated upon its external surface. No nerves have been traced into this mem- 
 brane. 
 
 Uses. — Each pleura forms an investment for the corresponding lung, separates it from 
 the parietes of the thorax and from the other viscera, and, at the same time, facilitates 
 its movements upon the walls of the thoracic cavity by means of the serosity, which is 
 constantly exhaled and absorbed at its internal surface. 
 
 The Proper Tissue of the Lungs. 
 
 The pulmonary tissue appears like a spongy or vesicular texture, the cells of which 
 are filled with air. This is rendered apparent by the most simple inspection of the sur- 
 face of an inflated lung, either with the naked eye or with a lens. A microscopical ex- 
 amination of sections of a dried lung shows the existence of this cellular or vesicular tex- 
 ture in the most evident manner throughout the entire organ. The different shapes of 
 the cells and their unequal size may also be distinguished. 
 
 But what are the relations of the cells with each other 1 Do they communicate 
 throughout the whole extent of the lung, or only within a determinate space, or are they 
 independent of each other 1 In order to resolve these questions, it is necessary to ex- 
 amine the lung of a large animal, of the ox, for example, the structure of which is simi- 
 lar to that of the human lung, on which the same observations may be subsequently re- 
 
 * [A fold of the pleura reaching' from the lower edge of the root of the lung downward to the diaphragm, 
 is called the ligamentum latum pulmonis. It is triangular ; its base is attached to the diaphragm, one side to 
 the lung, and the other to the mediastinum.] 
 
 t According to Meckel, the anterior mediastinum is the portion of the septum situated in front of the heart, 
 just as the posterior mediastinum is the part situated behind that organ. 
 
 X [It is covered with a squamous epithelium, and cilia have been observed upon it in some of the mam- 
 malia.] 
 
 ^ [Beneath the pleura another cellular layer may be demonstrated ; and in the lung of the seal and leopard 
 an elastic coat is said to exist. 1 
 
THE LUN38. 415 
 
 peated. We then observe that the surface of the lung is traversed by lines, dividing it 
 into lozenge-shaped compartments ; and if the lung be previously inflated, it will be seen 
 that the surface is slightly depressed opposite these lines, but that it bulges out between 
 them. If, by means of a dehcate tube, air be blown under the pleura, or if the lung be 
 forcibly inflated through the trachea, so as to rupture some of the vesicles and produce 
 emphysema, we then perceive that the lines bounding the lozenge-shaped intervals cor- 
 respond to thin layers of very delicate, but tolerably loose cellular tissue, which divide the 
 lung into a large number of groups or cells, which may be completely separated from 
 each other by dissection, until at last we arrive at the pedicles by which they are united 
 into a common mass. 
 
 These groups of cells are the lobules of the lung; the cellular tissue uniting them is the 
 interlobular cellular tissue, which is extremely delicate, never loaded with fat, but oft,en 
 infiltrated with serosity, and is subject to emphysema. A great number of lymphatic 
 vessels traverse this cellular tissue : they are often visible to the naked eye, and are 
 always easily injected ; they pass deeply into the substance of the lung. 
 
 The pulmonary lobules do not communicate with each other, but each is perfectly in- 
 dependent of the rest. This fact is shown by inflation ; it is most distinctly proved by 
 dissection ; and an examination of the lungs of the foetus will remove all doubts con- 
 cerning it. The pleura and the interlobular cellular tissue having but little strength in 
 the fcEtus, the lobules become separated without dissection, resemble grapes attached to 
 their footstalks, and hang from a common stem, formed by the divisions of the bronchi 
 and the pulmonary vessels. 
 
 This independence of the lobules is also proved by pathological anatomy : thus, we con- 
 tinually find one lobule infiltrated with serum, with pus, or with tubercular matter, in the 
 midst of perfectly healthy lobules. 
 
 Each lobule, then, is a small lung, and may act independently of those by which it is 
 surrounded. I have satisfied myself, by a great number of experiments, that the lobules 
 are not all equally permeable to the air, and that a moderate inflation of the lungs, made 
 as much as possible within the limits of an ordinary inspiration, does not, perhaps, dilate 
 one third of the pulmonary lobules. I have observed, and this fact appears to me of 
 great importance, that the most permeable lobules are those of the apex of the lung ; and 
 this, perhaps, will explain the greater frequency of tubercles in that situation.* There 
 are some lobules in the lung which are kept, as it were, in reserve, and only act in forced 
 inspirations.! 
 
 The puhnonary lobules vary much in shape ; all the superficial ones resemble a pyra- 
 mid, the base of which is at the surface of the lung ; the deep lobules lie along the bron- 
 chial tubes, have numerous facettes, and are exactly fitted to each other, like the frag- 
 ments of mosaic work ; but they are so irregular in form, that it would be equally diffi- 
 cult and useless to give a description of them. 
 
 The lung, then, is a collection of an immense number of lobules, placed along the bron- 
 chial tubes and pulmonary vessels, which serve as a support and framework for them, and 
 to which they are appended by pedicles ; they are united to each other by serous cellu- 
 lar tissue, and are all covered by one great cell formed by the pleura, which merely 
 unites together this great number of parts. 
 
 The problem of the texture of the lungs reduces itself, therefore, to the determination 
 of the structure of a single lobule ; but the difficulty is rather postponed than got rid of, 
 for each lobule is a little lung, receiving an air-tube and an artery, and giving out several 
 veins and lymphatics. 
 
 Before describing the arrangement of the air-tube, and the vessels in each lobule, we 
 shall say a few words upon the structure of the lobule itself 
 
 Each lobule is an agglomeration of cells and of vesicles, all of which communicate 
 with each other.J These cells are always full of air. Their size is not always the same. 
 M. Magendie has already shown that the pulmonary cells are smaller in the infant than 
 in the adult, and smaller in the adult than in the aged.§ Nor is the size of the different 
 cells in the saime lobule constantly uniform. All the cells of the same lobule communi- 
 cate, but they are not all equally permeable. t Thus, in a given degree of inspiration, 
 some cells only are distended, while others require a greater degree of dilatation. The 
 septa between the cells of a lobule are incomplete,^ and consist of filaments or lamellae ; 
 and the reticulated arrangement of the cells, which is so evident to the naked eye in the 
 lung of the frog, seems to me to represent with tolerable accuracy the appearance of the 
 human lung under the simple microscope. 
 
 * It is rather too much to say that pneumonia almost always attacks the base of the lungs ; this disease has 
 no special locality ; it perhaps as often affects the apex as the base. 
 
 t In ordinary respiration, perhaps not more than one third of the lung is in action ; exercise and yawning 
 are probably required, from the necessity for bringing the whole lung into action. Thus, a great number of tu- 
 bercles may exist in the lung without manifesting their presence by impeding ordinary respiration. It is in 
 Tiolent inajnration, in exercise, in efforts of the voice, and in all movements during which the whole of the 
 lungs is called into play, that we detect the existence of a lesion in the central organ of respiration. 
 
 { See note, p. 419. 
 
 ^ Diseases have a remarkable influence upon their size ; in chronic catarrh, and in some varieties of asthma, 
 we find the pulmonary cells excessively dilated. Laennechas called this dilatation pulmonary emiihysemo. 
 
416 SPLANCHNOLOGY. 
 
 With regard to the structure of the cells,* we cannot admit the existence of muscular 
 fibres round them ; the anatomist is unable to demonstrate them, and physiology rejects 
 them. Tlie most probable opinion is, that they are formed of dense cellular tissue, or of 
 an elastic fibrous tissue, and that the bloodvessels are ranrified upon their parietes. 
 
 The Air-tubes. 
 
 The air-tubes of the lungs consist of the trachea, the bronchi, and their divisioris. 
 
 The Trachea. 
 
 The trachea (from rpaxvg, rough), or aspcria arteria ib,fiffs. 170, 171), is the common 
 trunk of the air-tubes of the lungs ; it is situated between the larynx {a,Jig. 171), of which 
 it is a continuation, and the bronchi (p p'), which are nothing more than its bifurcation in 
 front of the vertebral column, extending from the fifth cervical to the third dorsal verte- 
 bra, t In this situation, however, it is movable, and may easily be pushed to the right 
 or left side. This mobility has occasioned serious accidents in tracheotomy, and has led 
 to the invention of an instrument for fixing the trachea.^ Its direction is vertical ; it 
 occupies the median line above, but appears to be slightly deflected to the right side be- 
 low. I have often seen it somewhat flexuous, but these slight deviations only existed 
 when the neck was bent upon the thorax ; they disappeared during extension. 
 
 Dimensions. — The length of the trachea equals that of the space between the fifth cer- 
 vical and the third dorsal vertebrae, and is, therefore, from four to five inches ; but it 
 varies according as the larynx is raised or depressed, and as the neck is flexed or ex- 
 tended. The difference produced in its length, by the utmost elongation and shortening, 
 may be about half its entire length, i. e., from two inches to two inches and a half; its 
 shortening is limited by the contact of its cartilaginous rings. ^ 
 
 The diameter of the trachea is determined by that of the cricoid cartilage of the larynx ; 
 it is much wider in the male than in the female, and after than before puberty. Indi- 
 viduals who have been many years labouring under chronic catarrh have the air-passages 
 remarkably large, especially the trachea. The mean diameter of the trachea is from 
 ten to twelve lines in the male, and from nine to ten in the female. The trachea is not 
 of equal diameter throughout ; it is almost always dilated at its lower extremity, Avhere 
 it bifurcates. In some subjects it gradually increases in size from above downward, 
 and resembles a sort of truncated cone, with the base below. 
 
 External Surface, Form, and Relations. — In front and on the sides the trachea is cylin- 
 drical {fig. 170), but is flattened behind {fig. 171), so that it resembles a cylinder, the 
 posterior fourth or third of which has been removed. The external surface is rough, 
 and, as it were, interrupted by circular ridges, which correspond to the cartilaginous rings. 
 The relations of its external surface must be examined in the neck and in the thorax. 
 
 Relations of the Cervical Portion (x,fig. 140). — In front the trachea is in relation with 
 the thyroid body, the isthmus of which being sometimes very narrow and sometimes 
 very largely developed, covers a greater or less number of the rings of the trachea. In 
 general, the first ring of the trachea is above the isthmus of the thyroid. Below the 
 thyroid body the trachea is in relation with the stemo-thyroid muscles, the edges of 
 which are separated only by the linea alba of the neck ; also with the cerviced fascia, the 
 thyroid plexus of veins, a considerable quantity of cellular tissue, the thyroid artery of 
 Neubauer, when it exists, and the brachio-cephalic artery, which always passes a little 
 above the supra-sternal notch. All these relations are of the greatest importance in ref- 
 erence to the operation of tracheotomy. On the sides the trachea is embraced by the 
 lateral portions of the thyroid body, and, therefore, in diseases of that organ, the corre- 
 sponding part of the trachea is deformed, flattened on the sides, and elliptical, or even 
 triangular. The compression of this canal may be carried so far as to produce suffoca- 
 tion. The common carotid artery and the pneumo-gastric nerve are in contact with it 
 on either side ; and hence the possibility of wounding that artery in the operation of 
 tracheotomy. A great number of lymphatic glands are situated upon the sides of the 
 trachea, and may become so large as to prevent the passage of the air. Lastly, all the 
 relations of the trachea, excepting those with the thyroid body, take place through the 
 medium of a very loose cellular tissue in which this canal is imbedded. 
 
 Behind, the trachea is flat and membranous, and is in relation with the oesophagus, 
 which projects a little beyond it on the left side, and separates it from the vertebral col- 
 
 * See note, p. 419. 
 
 t The terai trachea is derived from the roughness produced by the projection of the cartilages of the wind- 
 pipe. The application of the term arteria, by the ancients, to the vessels which carry red blood, arose from 
 a serious anatomical mistake. These vessels being habitually empty in the dead body, it was supposed that 
 they contained air during life ; and hence the name artery, which tliey still retain. 
 
 t By a surgeon of the name of Buchot. The mobility of the trachea is an obstacle to its puncture in the 
 operation of tracheotomy. 
 
 ^ The elongation and shortening of the trachea is much more limited in man than in birds, in which the 
 rings of the trachea are moved by longitudinal muscles, and can be drawn within each other ; in the greatest 
 possible degree of shortening three rings overlap each other, so as to equal only one in height ; and, therefore, 
 the trachea of a bird may be diminished by two thirds. These peculiarities of structure are connected with 
 the different uses of the parts ; the trachea in man and other mammalia merely conveying the air (unporte-verU), 
 while tlie trachea of birds conveys the voice (vn porte-voix). 
 
THE LUNGS. 
 
 417 
 
 omn. The left recurrent nenre is situated in the groove formed between the trachea and 
 the oesophagus in this direction ; the right recurrent nerve lies behind the trachea. 
 
 The inunediate relation of the trachea with the oesophagus explains why foreign bodies 
 arrested in the gullet may produce suffocation, and require the perfonnance of trache- 
 otomy. 
 
 The softness and flexibility of the trachea opposite the oesophagus have appeared to 
 some physiologists to be intended merely to facilitate the dilatation of the latter during 
 the passing of the food ; but we shall see that the air-tubes continue to be membranous 
 behind, even where they have no relation with the oesophagus, and comparative anatomy, 
 which shows the trachea to be cylindrical in the bird, and angular behind in the ox, the 
 sheep, &c., most completely refutes this opinion. 
 
 Rdaiions of the Thoracic Portion of the Trachea. — In the thorax, the trachea occupies 
 the posterior mediastinum. It corresponds in. front, proceeding from above downward, 
 with the sternum and the sterno-thyroid muscles ; with the left brachio-cephalic vein (c, 
 fig. 170) ; with the brachio-cephalic artery (A), an aneurism of which may open into the 
 trachea ; its left side is, as it were, embraced between the brachio-cephalic artery (A) 
 and the left common carotid (;) ; with the back part of the arch of the aorta {g), which 
 rests immediately upon it, and hence the dyspnoea which so generfdly accompanies aneu- 
 rism of the aorta, and the frequency of its bursting into the windpipe ; and, lastly, lower 
 down, with the bifurcation of the pulmonary artery, which corresponds with that of the 
 trachea. 
 
 The trachea is in relation behind with the oesophagus, which separates it from the spinal 
 column ; and on the sides with those portions of the pleurae which form the mediastinum, 
 with the pneumogastric nerves, and with the upper part of the recurrent nerves. 
 
 In all its thoracic portion the trachea is surrounded by numerous lymphatic vessels and 
 glands, and by a loose and very abundant cullular tissue, which communicates with that 
 of the cervical region. These lymphatic vessels and glands with the loose cellular tissue 
 are the parts immediately adjoining the trachea ; and it may readily be conceived that 
 enlargement of the glands may be productive of serious consequences. 
 
 Internal Sarface. — The internal surface of the trachea is of a rosy colour, and presents 
 the same circular ridges as the external surface, but they are more distinct. It is also 
 remarkable in its membranous portion for the projection of certain vertical fasciculi, to 
 which we shall again refer when speaking of the structure of these parts. 
 
 The Bronchi. 
 
 The bronchi {(JpSyxoc, gutter, p p,Jig. 171) are the two branches formed by the bifiirca- 
 tion of the trachea, which Ft^. 171. 
 
 spread out from each other at 
 a right or a slightly obtuse 
 angle ; one {p) is intended for 
 the right, the other for the 
 left (p') lung. A tolerably 
 strong triangular ligament 
 exists at the angle of the bi- 
 furcation, and seems intend- 
 ed to prevent too great sep- 
 aration of the bronchi. 
 
 The bronchi differ from 
 each other in many respects ; 
 first, in width. The right 
 bronchus is much wider than 
 the left, and its diameter is 
 not much less than that of 
 the trachea. In a female 
 whose trachea w£is ten lines 
 in diameter, the right bron- 
 chus was eight, and the left 
 five. This difference in width 
 corresponds with the differ- 
 ence in the size of the two 
 lungs, and may afford a toler- 
 ably correct measure of that 
 size ; they differ also in length, 
 the right bronchus being one inch in length, the left two ; also in direction, the right 
 bronchus passing less obhquely than the left, probably because it enters the correspond- 
 ing lung sooner than the latter ; and, lastly, in their relations. Thus, the right bronchus 
 is embraced by the vena azygos, which forms a loop immediately above it, in order to 
 terminate in the vena cava superior. The left bronchus is embraced above by the arch 
 of the aorta {g), and has an important relation with the oesophagus behind, which it 
 
 Ggg 
 
4ih SPLANCHNOLOGY. 
 
 crosses obliquely. Both are connected with the pulmonary plexus of nerves ; both are 
 surrounded with lymphatic glands, remarkable for their black colour, and for being fre- 
 quently diseased, and which in some measure fill up the angle formed by the bifurcation 
 of the trachea ; and, lastly, both have the following relations with the pulmonary artery 
 and veins. Each pulmonary artery {k k') is situated in front of the corresponding bron- 
 chus, then passes above, and finally behind it. The two puhnonary veins on each side {I I, 
 mm) are situated upon the same vertical plane as the corresponding artery ; they pass up- 
 ward in front ofthe artery and the bronchus, which is, therefore, behind the bloodvessels.* 
 
 The shape of the bronchi exactly resembles that of the trachea, i. e, they represent 
 cylinders, the posterior fourth of which has been removed, and which are formed by par- 
 allel rings. The area of the two bronchi is greater than that of the trachea, in the same 
 way as the area of the bronchial ramifications is greater than that of the bronchi them- 
 selves, so that the velocity of the expired air increases as it approaches the exterior. 
 
 At the root of the lungs the bronchi divide into two equal branches, but in a some- 
 what different manner. The upper branch of the bifurcation of the right bronchus is the 
 smaller, and is intended for the upper lobe of the lung, in order to reach which it is bent 
 slightly upward. The lower branch, which is larger, follows the original direction, and 
 after passing about an inch, divides into two unequal branches, a small one for the mid- 
 dle lobe, and a larger one for the lower lobe. I have once seen a small bronchus pro- 
 ceeding from the lower part of the trachea directly to the apex of the right lung ; the 
 vena azygos passed between it and the regular bronchus.t 
 
 The secondary divisions are precisely the same in the two lungs ; each branch of a 
 bifurcation becomes bifurcated in its turn. All these ramifications pursue a diverging 
 course, some ascending, others descending, and, after proceeding for a variable distance, 
 they again bifurcate ; so that, by separating a small portion of the pulmonary substance, 
 we can see that several diverging series of tubes proceed in succession from a bronchial 
 trunk, and pass outward into the tissue of the lung. The prevailing mode of division of 
 the air-tubes in the lungs is that called dichotomous, viz., a division into two equal branch- 
 es, which we shall afterward find to be the most favourable to the rapid transmission of 
 the contents of any vessel. (See Aeteries.) The two branches of a bifurcation sep- 
 arate at an acute angle, and a spur-shaped process, situated within the tube at the an- 
 gle of division, cuts and divides the column of air. However, some small bronchial 
 tubes are not unfrequently found arising directly from a principal division, to be distrib- 
 uted to the nearest pulmonary lobules. The number of subdivisions, which always cor- 
 responds with that of the pulmonary veins, is not so great as might at first be supposed ; 
 there are not many more than fifteen. 
 
 The form of the bronchial ramifications (bronchia) differs essentially from that of the 
 bronchi themselves and of the trachea. They represent, indeed, a complete cylinder, 
 which is not truncated behind ; and the cartilages, instead of forming rings, have another 
 arrangement, which I shall point out when speaking of their structure. 
 
 Relations. — The first divisions ofthe bronchi are surrounded, even in the substance of 
 the lung, by very numerous and dark-coloured bronchial lymphatic glands, enlargement 
 of which is a very frequent result of chronic bronchitis, and may cause suffocation. 
 
 The bronchial ramifications, as I have said, support the pulmonary lobules, which are 
 applied to and moulded upon them, and are united to them by very loose cellular tissue. 
 
 The following are their relations with the branches of the pulmonary artery and veins : 
 the artery always accompanies the bronchial ramification, and is situated behind it ; the 
 vein is often separated from it ; the artery and vein are not unfrequently found interla- 
 ced around the corresponding bronchial tube. 
 
 Relations of the Bronchial Ramifications with the Pulmonary Lobules. — ^Each pulmonary 
 lobule has its bronchial tube. This tube is cylindrical, of uniform diameter throughout, 
 and entirely membranous ; having entered the lobule, it dilates into a small ampulla, and 
 disappears. There can be little doubt that these small ampullae have deceived Malpighi, 
 Reisseisen, and others, who have stated that the bronchial tubes terminate in culs-de- 
 sac ; so that, according to these authors, each pulmonary cell is the termination of a par- 
 ticular bronchicd tube. But it is evident that such cannot be the case, for, on the one 
 hand, the bronchial tubes are not sufficiently numerous, and, on the other, it can be shown 
 that only a single bronchial tube enters into each group of cells or each lobule. If we 
 inject with tallow a lung which has previously been deprived of air, either by an effu- 
 sion in the chest during life, or by an artificial one after death, it wiU be seen that the 
 injection is divided into small globules or rounded tubercles, which correspond to so 
 many pulmonary ceUs, and that these globules are all connected with a common pedicle, 
 corresponding to the bronchial tube. 
 
 Reisseisen, who has made this injection, thinks that the granular appearance of the 
 injected matter represents the culs-de-sac, into which it had penetrated.^ 
 
 * [In consequence of the oblique direction of the left bronchus towards the root of the lung, the correspond- 
 ing pulmonary artery is placed somewhat above it, and the pulmonary veins below it ; on the right side, the 
 pulmonary artery is in the middle, the bronchus above, and the veins below.] 
 
 t This appears to be the natural arrangement iu the sheep and the ox. 
 
 t [According to Reisseisen, each small bronchial tube, on entering its corresponding lobule, divides and sub- 
 
THE LUNGS. 419 
 
 * ^ Structure of the Trachea, Bronchi, and Bronchial Ramijicattons. 
 
 Structure of the Trachea. — The trachea is composed of a series of imperfect cartilagi- 
 nous rings, separated by an equal number of fibrous rings, and hence it has a knotted ap- 
 pearance ; these cartilages keep the canal permanently open. Had the trachea been en- 
 tirely membranous, it would have collapsed during inspiration, which tends to produce 
 a vacuum in the thorax, and this collapse would have prevented the entrance of the air. 
 The number of the cartilaginous rings varies from fifteen to twenty. They are more 
 prominent on the internal than on the external surface of the trachea. In some subjects 
 they form two thirds, in others three fourths or four fifths of a circle. Each ring has 
 two surfaces, one anterior and convex, the other posterior and concave ; an upper and 
 a lower edge, both of which are thin, and give attachment to the fibrous rings ; and two 
 extremities, which terminate abruptly, without being inflected or thickened. In general, 
 there is but little regularity in the arrangement of these rings ; they are not exactly par- 
 allel, nor are they of equal depth, which varies from a line to a line and a half, two, or 
 even two lines and a half; and the same ring is often of unequal depth at different pakits. 
 Two rings are often united for a certain extent, and sometimes a ring is found birarca- 
 ted ; indeed, it is probable that differences in the number of the rings depend upon their 
 thus uniting or dividing. They are sufliciently thin to £illow of being compressed, so 
 that the opposite surfaces may touch without breaking. Their eljisticity enables them 
 to recover their original position immediately, and thus permit free access to the air. 
 They can only be broken when ossified, which is frequently the case in the aged. 
 
 The first ring and the two lower rings present some peculiarities. The first is broad- 
 er than any of the others, especially in the middle line, and it is often continuous with 
 the cricoid cartilage.* 
 
 The last ring of the trachea, which forms the. transition between it and the bronchi, 
 has the following characters : the middle part is prolonged considerably dowmward, and 
 curved backward, forming a very acute angle, and is developed into a spur-shaped pro- 
 jection within the trachea, which separates the two bronchi. The two half rings result- 
 ing from this arrangement/ constitute the two first rings of the bronchi. The last ring 
 but one of the trachea presents an angular inflection in the middle, less marked, howev- 
 er, than that observed in the lowest ring. 
 
 The Fibrous Tissue of the Trachea. — This is arranged in the following manner : a 
 fibrous cylinder commences at the lower edge of the cricoid cartilage ; the cartilaginous 
 rings are situated within the substance of this cylinder in such a manner, that the thick- 
 er layer of fibrous tissue lies on their exterior, so that, at first sight, their internal sur- 
 faces would appear to be in immediate contact with the mucous membrane. In the pos- 
 terior part of the trachea, where the cartilaginous rings are wanting, the fibrous tissue 
 alone forms its basis or framework. 
 
 The Muscular Fibres of the Trachea. — If we carefully remove the fibrous tissue from 
 the back of the trachea, opposite its membranous portion, we arrive at certain transverse 
 muscular fibres, extending from one end of each ring to the other, and also occupying 
 the intervals between the rings. The existence of these muscular fibres, which I have 
 seen forming a layer half a line tliick in certain cases of chronic catarrh, cannot be doubt- 
 ed. It is evident that their contraction must draw the ends of the rings towards each 
 other, and therefore narrow the trachea, the diminution in the width of which is limited 
 by the contact of the ends of the rings. 
 
 The Longitudinal Yellow Fasciculi. — In the membranous portion of the trachea, be- 
 
 divides in a certain uniform order into numerous tv„ i-rn 
 
 twigs (<,_/r^. 172), which, extending towards tbe °' 
 
 surface of the lobule, gradually decrease in di- 
 ameter, but increase in number, and at length ter- 
 minate in clusters of short, free, closed and round- 
 ed extremities (c c) ; these are the pulmonary 
 cells, which vary from ij^ to -g^ of an inch in 
 diameter. Not only are the several lobules in- 
 dependent of each other, but the cells of each 
 lobule have no communication with one another 
 except indirectly through the twig or twigs from 
 which they proceed. 
 
 This view of the minute structure of the lung, 
 which is opposed to the opinion of M. Cruveil- 
 hier, receives support from what is known con- 
 cerning the development of the lungs, and from 
 the analogy between these organs and the com- 
 I)onnd glands. ^___^__ 
 
 In_^g'. 172, after Reisseisen, a shows the nat- "*^^ici^ h 
 
 ural size of the portion represented, magnified 
 
 about nine diameters in 6. The bronchial twigs Minute itmcture of the lung, 
 
 and pulmonary cells are seen distended with air ; the knots or projections (i) on the sides of some of the ^ga 
 indicate the commencement of other twigs, into which no air has passed.] 
 
 * I have met with one case in which the thin upper rings of the trachea and the cricoid cartilage were 
 joined together, l)ut only on one side ; the crico-thyroid muscle and the inferior constrictor of the pharynx ev- 
 idently arose from the first ring of the trachea. This continuity of the cricoid cartilage with the trachea 
 manifestly proves that the rings of the latter arc cartilages, and not fihro-cartilag-es. 
 
420 SPLANCHNOLOGY. 
 
 tween the muscular anS'ttie mucous layer, are situated a great number of parallel, lon- 
 gitudinal, yellow fasciculi, which, at first sight, resemble longitudinal folds, but are not 
 at all effaced by distension ; these fasciculi adhere to, and produce an elevation of, the 
 mucous membrane, and opposite the bifurcation of the trachea they also divide, and are 
 continued into the bronchi. 
 
 The nature of this tissue is not well known ; it can only belong to the muscular or to 
 the yellow elastic tissue, though I would rather incline to the latter opinion. According 
 to either supposition, its use is to prevent too great an elongation of the trachea and the 
 bronchi ; actively in the one case, and by virtue of its elasticity in the other. Not un- 
 frequently some longitudinal fasciculi are found behind the cartilaginous rings. 
 
 The Tracheal Glands. — If we carefully examine the posterior surface of the trachea, 
 we find a certain number of ovoid flattened glands (see^^. 171), placed upon the outer 
 surface of the fibrous membrane ; and, by removing this membrane, we see a tolerably 
 thick, but not continuous, layer of similar glands between the fibrous and the muscular 
 coate ; and, moreover, if either the inner or the outer layer of the fibrous tissue, situated 
 between the cartilaginous rings, be removed, a series of much smaller glands will be 
 found between these layers, occupying the intervals between the rings, and even ex- 
 tending behind them. 
 
 The Mucous Membrane. — This is a continuation of the mucous membrane of the larynx , 
 it is remarkable for its tenuity, which permits the colour of the subjacent parts to be 
 seen through it, and for its intimate adhesion to the structures covered by it. The lon- 
 gitudinal folds of which some authors speak do not exist ; the yellow longitudinal fas- 
 ciculi have been mistaken for them. Lastly, it presents a great number of openings, 
 from which mucus can be expressed. These openings are nothing more than the orii- 
 ces of the excretory ducts of the tracheeil glands.* 
 
 The Vessels and Nerves. — The arteries Of the trachea are derived from the superior and 
 inferior thyroid. The veins are generally arranged thus : some venous trunks running 
 along the inner surface of the trachea, beneath the mucous membrane, receive on each 
 side, in the same manner as the vena azygos, small veins corresponding to the intervals 
 between the cartilaginous rings, and then terminate in the neighbouring veins. The 
 lymphatic vessels are very numerous ; they enter the surrounding glands, which are of 
 considerable size. The nerves are derived from the pneumogastrics. 
 Structure of the Bronchi. 
 
 The structure of the bronchi is exactly the same as that of the trachea. The lett 
 bronchus has ten or twelve cartilaginous rings ; the right has five or six. They both 
 possess transverse muscular fibres, longitudinal yellow fasciculi, glands, &c. Their arter- 
 ies generally arise directly from the aorta, and are named bronchial. The veins of the right 
 bronchus enter the vena azygos ; those of the left terminate in the superior intercostal. 
 
 Structure of the Bronchial Ramifications {Bronchia). — The fibrous cylinder of the trachea 
 and the bronchi is prolonged into the bronchial ramifications. The cartilaginous rings 
 are remarkably modified beyond the first division of the bronchi ; they become divided 
 into segments, which together form a complete ring, so that there is no longer any mem- 
 branous portion, properly so called, and the bronchial tubes become perfectly cylindrical. 
 The segments above mentioned are oblong, curved, terminated by very elongated angles, 
 and so arranged that they can overlap and be mutually received between each other. 
 They are also united together by fibrous tissue. This arrangement of curved and angu- 
 lar segments exists as far as the last bifurcations of the bronchial tubes ; but the size 
 of the segments gradually diminishes, so that they soon form only narrow lines, and ul- 
 timately mere cartilaginous points. The fibrous and membranous constituents of the 
 cylinder preponderate more and more over the cartilaginous laminae, which disappear be- 
 yond the ultimate bifurcations of the bronchial tubes, being found last at the several an- 
 gles of bifurcation : the ultimate bronchial ramifications are altogether membranous. 
 
 The mucous membrane is prolonged to the very last ramifications, where it becomes 
 extremely thin. The longitudinal elastic fasciculi, which were limited to the membra 
 nous portion of the bronchi, are expanded over the entire surface of the bronchial tubes 
 beyond their first subdivision. The muscular fibres, which are confined to the mem 
 branous portion in the trachea and bronchi, become circular on the inner side of th» 
 bronchial ramifications, and form an uninterrupted but very thin layer, precisely resem 
 bling the circular fibres of the intestinal canal, t When we consider, on the one hand. 
 
 * structure of the Trachea.— iTtin muscular fibres of the trachea are of the involuntary class (see p. 323), 
 and are attached to the internal surface of the ends of the rings : the longitudinal fibres exist all round tht 
 trachea, but are collected into bundles on its membranous portion only ; they are believed to consist of elastif 
 tissue. 
 
 The glands of the trachea and bronchi are compound ; its mucous membrane is covered vfith a columnar 
 epithelium, and is provided with cilia, which urge the secretions upward towards the larynx.] 
 
 t Structure of the Bronchi and their Branches. — [According to Reisseisen, the fibrous cylinder gradually de- 
 generates, in the smallest bronchial tubes, into cellular tissue ; according to the same author, the longitudinal 
 elastic and the circular fibres can be traced as far as the tubes can be opened. The contractility of the pul- 
 monary tissue on the application of galvanism, recently observed by Dr. C. J. B. Williams, establishes the 
 muscularity of the circular fibres of the bronchial tubes. The mucous membrane, as in the trachea, has a co- 
 lumnar and ciliated epithelium ; it of course enters into and lines the pulmonary cells.] 
 
THE LUNGS. 421 
 
 the arrangement of the cartilaginous segments, which appear, as it were, shaped ex- 
 pressly for the purpose of fitting between each other at their extremities, and of consti- 
 tuting an apparatus capable of being moved, and, on the other, the existence of circular 
 contractile fibres on the inner surface of these segments, we cannot doubt that they are 
 moved upon each other, the extent of such motion being measured by the space they 
 have to traverse in order to come into contact. When this is effected, the canals must 
 be almost completely obliterated.* 
 
 The Pulmonary Vessels and Nerves. 
 
 Besides the trachea, the bronchi and the bronchial ramifications, which may be re- 
 garded as forming the framework of the lungs, these organs receive two sets of arteries, 
 viz., the pulmonary and the bronchial, and give out two sets of veins, also called _p?<i[wio- 
 nary and bronchial. A very great number of lymphatics arise from their interior, and 
 from their surfaces, and they are penetrated by important nerves. 
 
 The size of the pulmonary artery is equal to, if not greater than that of the aorta ; J:he 
 bronchial arteries appear to be distributed upon the bronchi and their ramifications, which 
 they exactly follow. 
 
 The pulmonary veins correspond with the pulmonary artery : they are two in number 
 for each lung. The bronchial veins correspond with the bronchial arteries, and terminate 
 in the vena azygos on the right side, and in the superior intercostal vein on the left. 
 
 Within the lung, as well as at its root, the pulmonary arteries and veins always ac- 
 company the bronchial tubes. The three vessels may be distinguished from each other 
 upon sections of the organ by the following characters : the artery remains open, or 
 rather so, and is of a white colour ; the bronchus is also open, but of a more or less rosy 
 colour, and contains a frothy mucus, which may be pressed out of it ; the vein is collap- 
 sed, and much more difficult to be seen than the artery. The relations of these three 
 kinds of vessels have not appeared to me to be constant. Notwithstanding the investi- 
 gations of Haller, the arrangement of the bronchial with regard to the pulmonary arter- 
 ies and veins is not well known, t 
 
 I ought to notice the easy communication between the arteries and the pulmonary 
 veins and bronchial ramifications. The coarsest injection pushed with moderate force 
 passes with the greatest facility from the arteries into the pulmonary veins and the 
 bronchial tubes ;t only infljmied portions of the lung have appeared to me to be imper- 
 meable. 
 
 The lymphatic vessels, both superficial and deep, are very numerous ; they terminate 
 in the bronchial and tracheal glands, the number and size of which sufficiently declare 
 their importance. The black colour of these glands only begins to appear from the tenth 
 to the twentieth year. 
 
 The iierves of the lungs are principally derived from the pneumogastrics, but they re- 
 ceive some branches from the ganglionic system. They form a large plexus behind the 
 bronchi, with the divisions of which they penetrate into the substance of the lung. I 
 should observe that there is only one great pulmonary plexus common to the two lungs ; 
 and on this circumstance the sympathy between the two is without doubt partially de- 
 pendant. 
 
 Development. — According to Meckel, the lungs are among the latest organs to appear 
 in the foetus ; they can only be distinctly recognised amid the other contents of the tho- 
 rax, towards the end of the second month of intra-uterine existence.^ 
 
 * These anatomical facts explain, in a remarkable manner, all the phenomena of nervous asthma, nervous 
 cuffocation, &c. 
 
 t [The following are the results of Reisseisen's observations on this subject : the branches of the pulmonary 
 artery accompany the bronchial tubes, and do not anastomose until their termination in a dense network of 
 capillaries npon the walls of the air-cells. These capillarie» have very thin coats ; they are about one twen- 
 tieth the diameter of a pulmonary cell, and the meshes which they form are scarcely so wide as the vessels 
 themselves. From this network arise tlie branches of the pulmonary veins, which unite into larger and larger 
 trunks, so as to correspond with the divisions of the pulmonary artery ; these veins have no valves, and their 
 caliber is not greater, perhaps less, than that of the artery. 
 > Such is the chief mcxie of distribution of the pulmonary artery and veins ; but both vessels, as indicated be- 
 low, also communicate with the bronchial arteries. 
 
 The bronchial arteries are the nutrient vessels of the lung ; some of their branches are distributed upon the 
 air-tubes and to their lining membrane, even as far as the air-cells, upon all the pulmonary vessels and nerves, 
 and to the bronchial lymphatic glands ; while others, passing between the lobules, or upon the surface of the 
 lung, anastomose with twigs from the pulmonary artery, and form, with the branches of the pulmonary vein, 
 a vascular network in those situations, but more particularly beneath the pleura. The branches distributed 
 to the lirger bronchia and vessels, and to the lymphatic glands, and also some of the vessels composing the 
 superficial network, terminate in the bronchial veins, which, however, cannot be traced very deeply into the 
 substance of the lung. But by far the greater number of the bronchial arteries end in the pulmonary veins ; 
 for example, those distributed deeply to the smaller air-tubes and pulmonary vessels, and to the air-cells, and 
 nearly all the vessels which enter into the formation of the interlobular and superficial network.] 
 
 i [This is due to rupture of the pulmonary vessels, which have exceedingly delicate coats, and are, perhaps, 
 less supported by surrounding tissue than the vessels of other organs.] 
 
 I> [The development of the lungs has been traced by various recent observers in frogs, birds, and mammalia, 
 including man ; according to Rathke and Miiller, it closely resembles, in its early stages, that of the compound 
 glands. In mammaUa, the lungs appear at first as a protuberance upon the anterior part of the (Esophagus, 
 consisting of a soft mass, like the primitive blastema of a gland : within this substance a more opaque portion 
 is formed, from which white lines extend, dividing and subdividing, and terminating in enlarged extremities 
 
422 SPLANCHNOLOGY. 
 
 The lung is smallest at the earliest period of its development. Its place appears then 
 to be occupied by the thymus, which is the only organ that is seen when the thorax is 
 opened, the lungs being situated behind it, upon each side of the vertebral column. The 
 development of the lung takes place in an inverse ratio to that of the thymus, the lung 
 increasing in proportion as the thymus diminishes. In the last two months of pregnancy 
 the lung is completely developed, and fit for performing respiration. 
 
 Tlie weight of the lung in the foetus and in the adult presents some differences, which 
 are well worthy of attention. During the whole period of intra-uterine life, the foetal 
 lung is specifically heavier than water ; but as soon as the infant respires, it become? 
 much lighter, and floats in water. 
 
 Yet the absolute weight of the lung is sensibly increased, because it receives a much 
 greater quantity of blood than it did previously. Before birth, the absolute weight of 
 the lung to that of the whole body is as 1 to 60 ; after birth, it is as 1 to 30. It follows, 
 therefore, that lungs which float in water, and which have acquired a much greater ab- 
 solute weight than they would have had in the foetus, must belong to an infant that has 
 respired. 
 
 After birth, the lung participates in the development of the rest of the body. At the 
 tmie of puberty it acquires the proportions which it subsequently presents. I have not 
 observed that the lungs are smaller and lighter in the aged than in the adult. 
 
 The colour of the lungs varies considerably at different periods. In the earlier periods 
 ot development, the lung of the foetus is of a delicate pink colour ; subsequently it be- 
 comes of a deep red, like lees of wine, and remains so until the time of birth. After 
 birth, it again becomes of a pink colour. Still later, from the tenth to the twentieth 
 year, black spots become visible at different points along the lines which form the loz- 
 enge-shaped intervals on its surface. These spots subsequently unite into lines or 
 patches, which give to the grayish surface of the organ a mottled appearance. The de- 
 velopment of the black matter is so clearly the effect of age, that it is very rare not to 
 find small masses of it in the apex or some other part of the lungs in the old subject. It 
 is worthy of notice, that the black matter appears simultaneously on the surface of the 
 lung, and in the lymphatic glands situated at its root and along the bronchi. 
 
 With regard to structure, it may be observed, that during the four or five earlier months 
 of gestation, the pulmonary lobules are perfectly distinct from each other ; they may be 
 separated by very gentle traction, on account of the weakness of the pleura and cellular 
 tissue which unites them, as compared with the pulmonary tissue itself. The cartila- 
 ginous rings begin to be visible after the third month. 
 
 Functions. — The lungs are the essential organs of respiration, that process by means 
 of which the blood, though dark and unfit for supporting life before entering these or- 
 gans, becomes red and vivifying. For the accomplishment of this function, the lungs 
 receive, on the one hand, the atmospheric air, and, on the other, the venous blood, the 
 whole of which, in the human subject, passes through the lungs. The air is not drawn 
 in by any power resident in the pulmonary tissue itself, but by the muscular action of 
 the parietes of the thorax ; the blood is propelled into it by the right ventricle of the 
 heart. While the blood undergoes the changes above mentioned, the atmospheric air 
 loses a portion of its oxygen, which is replaced by carbonic acid gas. The manner in 
 which these changes in the blood are effected is not yet weU known. 
 
 The Larynx.* 
 
 It is necessary to have several specimens, from subjects of different ages and sexes, 
 so as to be able to examine the genpred relations of the larynx in its natural situation ; 
 its cartilages separated from each other, its ligaments and muscles, its vessels and 
 nerves, and its mucous membrane. 
 
 The larynx is a sort of box (jnxis cava) or cartilaginous passage, consisting of several 
 movable pieces, which form a complex apparatus intended for the organ of the voice. 
 It is situated {v, fig. 140) in the median line, in the course of the air-passages, opening 
 into the pharynx (3) above, and being continuous with the trachea (x) below : it occu- , 
 pies the anterior and upper part of the neck, below the os hyoides, the movements of 
 which it follows, and in front of the vertebral column, being separated from it by the 
 pharynx : it is covered by the muscles of the sub-hyoid region, which intervene between 
 it and the skin, and it is, therefore, veiy liable to woimds, and may easily be reached by 
 the surgeon. Its mobility allows of its being raised, depressed, and carried forward or 
 backward, all of which movements are concerned both in deglutition and in the produc- 
 tion of different tones of the voice. It may also be carried to the right or left side ; but 
 these lateral displacements are most commonly produced by external violence, or by the 
 growth of tumours. 
 
 these are accompanied by bloodvessels, and are at first solid, but soon become hollowed ont, into the trachea, 
 bronchi, bronchial tubes, and air-cells.] 
 
 * The voice belongs essentially to the functions of relation, and, therefore, Bichat describes its organ after 
 the apparatus of locomotion ; but the anatomical connexions between the larynx and ihe respiratory organs 
 are such that all animals provided with lungs have a larynx also, while the larynx disappears where the lungs 
 oease to exist. 
 
THE LARYNX. 45J3 
 
 Dimensions. — The larynx appears like an expansion of the trachea, and has, therefore, 
 been denominated its head, caput asperez arteria. The exact determination of its dimen- 
 sions, according to age and sex, or in different individuals, and their relations to the 
 various qualities of the voice, would be extremely interesting in a physiological point of 
 view. Its greater size in the male than in the female, and the development it under- 
 goes in both sexes, but especially in the male, at the period of puberty, are among the 
 most remarkable phenomena in the human economy. 
 
 Form. — It is cyhndrical below, like the trachea, but is expanded above, and becomes 
 prismatic and triangular. It may, therefore, be compared to a three-sided pyramid, the 
 truncated apex of which is directed downward and the base upward ; it is perfectly sym- 
 metrical. 
 
 As the larynx is a very complicated organ, I shall describe, in succession, the numer- 
 ous parts which enter into its composition. Being intended to admit of the continual 
 passage of the air in the act of r-espiration, it must, therefore, present a constantly per- 
 vious cavity, having strong and elastic wedls ; but as it is also the organ of the voice, it 
 requires to be provided with a movable apparatus, subject to the wiU. We accordingly 
 find in it a cartilaginous skeleton or framework, much stronger than that of the trachea ; 
 certain articulations and ligaments, and a vocal apparatus, composed of four fibrous 
 bands, or vocal cords ; muscles, which move the different pieces of the cartilaginous 
 skeleton, and produce certain changes in the vocal apparatus indispensable for the pro- 
 duction of sounds ; a mucous membrane, lining its inner surface ; glands, which pour 
 out their fluid upon that surface ; and, lastly, certain vessels and nerves. 
 
 We cannot enter upon a general description of the organ untU we have studied sep- 
 arately its constituent parts. 
 
 The Cartilages of the Larynx. — ^These are five in number, of which three are median, 
 single, and symmetrical, viz., the cricoid, the thyroid, and the epiglottis ; and two are lat- 
 eral, viz., the arytenoid, of which the cornicula laryngis are merely appendages. The car- 
 tilaginous nodules, described by some authors under the name of the cune^orm cartilages, 
 and situated in the membranous fold extending from the arytenoid cartilages to the epi- 
 glottis, do not exist in the human subject. 
 
 The Cricoid Cartilage. — The cricoid or annular cartilage (c c', figs. 173 to 177) forms 
 the base of the larynx ; it is much thicker and stronger than any j^^ j73 
 
 of the others. Its form is that of a ring, whence its name («pi«of , 
 a ring); it is narrow in front (c,fig. 173), where it resembles a 
 ring of the trachea ; it is three or four times broader or deeper 
 behind (c'and c,fig. 175), where it forms by itself alone the great- 
 er part of the larynx, being there about an inch in height. Li 
 front, its external surface is sub-cutaneous in the median line ; on 
 each side it gives attachment to the crico-thyroid muscle, and 
 presents a smooth process (m, fig. 177) for articulating with the 
 thyroid cartilage. Behind, where it is covered by the mucous 
 membrane of the pharynx, it presents in the median line a verti- 
 cal projection, which gives attachment to some of the longitudi- 
 nal fibres of the oesophagus, and on each side a depression for 
 the posterior crico-arytenoid muscle. 
 
 Its internal surface is covered by the laryngeal mucous mem- 
 brane. 
 
 Its lower border is perfectly circular and slightly waved, and is 
 connected by a membrane with the first ring of the trachea ; 
 sometimes it is even united with it, and can only be distinguished by its greater thickness. 
 
 Its upper border is not exactly circular, but is oblong from before backward, as if the 
 ring had been flattened laterally. It is cut very obUquely forward and downward, or, 
 rather, it is deeply notched in front, where it is concave, and gives attachment to the 
 crico-thyroid membrane in the median line, and laterally by its inner lip to & fibrous 
 membrane, which is continuous veith the inferior vocal cord, and in the rest of its thick- 
 ness with the lateral crico-arytenoid muscle. 
 
 Behind, and on each side, is an oblong, articular facette, the arytenoid facettes (h h,fig. 
 173), which are directed outward and upward, and articulate with the arytenoid carti- 
 lages. Between these two facettes, the upper border of the cricoid is horizontal, and 
 very slightly notched, and gives attachment to the arytenoid muscle. The upper bor- 
 der of the cricoid cartilage is, therefore, horizontal behind, oblique at the sides, and hor- 
 izontal and slightly concave in front. The arytenoid facettes are situated upon the ob- 
 lique portion. 
 
 The Thyroid Cartilage. — The thyroid or scutiform cartilage (t,figs. 173 to 177), so na- 
 med because it has been compared to a shield (i^upcdf, a shield),* occupies the upper 
 and fore part of the larynx. It is formed by two quadrilateral plates (or alee), united at 
 an acute angle in the median line, and embracing the cricoid cartilage behind. Its aia- 
 
 * The name may also have been derived from its use. 
 
424 SPLANCHNOLOGY. 
 
 teriar or cutaneous surface presents in the median line an angular projection (below c, 
 fig. 173), more marked and deeply notched above, and completely effaced below; much 
 less distinct in the female, in whom it forms only a rounded surface, than in the male, 
 in whom it has received the special appellation of the pomum Adami. This angular pro- 
 jection does not appear until puberty ; it presents certain individual varieties, but these 
 do not appear to me to have any relation with the qualities of the voice. 
 
 On each side the surface {t, Jigs. 173, 174) is smooth and quadrilateral, and has two 
 tubercles behind ; one of which is superior (b), and the other inferior {d). The latter, 
 or larger, is prolonged upon the inferior border of the cartilage. The two tubercles are 
 united by an aponeurotic arch, but there is no oblique intermediate line, as has been gen- 
 erally alfirmed. These tubercles, and the imaginary line between them, separate the 
 anterior three fourths of the surface, which are covered by the thyro-hyoid muscle, from 
 the posterior fourth, which is covered by the inferior constrictor of the pharynx and the 
 sterno-thyroid muscle. The tubercles give attachment to these three muscles. 
 
 The posterior surface {fig. 175) presents, in the median line, a retreating angle, which 
 gives attachment to the thyro-arytenoid ligaments, or vocal cords, and to the thyro-ary- 
 tenoid muscles. This angle is sometimes so acute that the cartilage has the appear- 
 ance of having been subjected to strong lateral pressure. 
 
 On each side {t t) the posterior surface projects beyond the cricoid cartilage, and forms 
 part of the lateral groove of the larynx. It is lined by the pharyngeal mucous membrane, 
 and corresponds in part to the thyro- and crico-arytenoid muscles. 
 
 Its upper border is horizontal and sinuous, and gives attachment to the hyo-thyroid 
 membrane in its whole extent. It presents a notch (e, fig. 173) in the median line, which 
 is shallower, but broader and more rounded in the female than in the male. On the 
 sides there is a small prominence, which forms a continuation of the superior tubercle, and 
 is often wanting. More posteriorly, we find on each side a slight notch, bounded by cer- 
 tain processes called the great or superior comua {s, figs. 173, 174) of the thyroid cartilage. 
 
 The lower border is sinuous, and shorter than the upper, and hence the pyramidal shape 
 of the larynx. It presents a slight median projection, to which the crico-thyroid liga- 
 ment is attached ; in the rest of its extent, it gives insertion to the crico-thyroid muscle, 
 and presents a rough eminence, which forms a continuation of the inferior tubercle ; and 
 more posteriorly, on each side, a slight notch, bounded by the lesser or inferior comua {I, 
 Jigs. 173, 175) of the thyroid cartilage. 
 
 Its posterior borders (s r, fig. 174) are slightly sinuous, give attachment to the stylo- 
 pharyngei and palato-pharyngei, and rest upon the vertebral column. As the thyroid 
 cartilage projects behind the upper portion of the larynx, it may be regarded as protect- 
 ing the larynx by its posterior borders resting upon the vertebral column. 
 
 The comua of the thyroid cartilage are four in number, two superior and two inferior, and 
 appear to be prolongations of the posterior borders of the cartilage. They are all round- 
 ed, and are bent inward and backward ; the upper or great comua (s) are generally the 
 larger, and are united by ligaments to the os hyoides ; the lower or lesser comua (J) are 
 usually smaller, and articulate with the cricoid cartilage. 
 
 The Arytenoid Cartilages. — The arytenoid cartilages {a, figs. 173, 175 to 177) are two 
 in number,* are situated at the upper and back part of the larynx, and have a pyramidal 
 and triangular form ; they are directed vertically, and bent backward like the lip of an 
 ewer, whence their name {dptraiua, a funnel). Their posterior surface (fig. 175) is trian- 
 gular, broad, and concave, and receives the arytenoid muscle ; their internal surface is 
 fined by the mucous membrane of the larynx ; their anterior surface (fig. 173) is convex, 
 narrow, rough, and furrowed, and corresponds to the series of glands called tlie aryte- 
 noid glands, and to the superior vocal cord ; their base is very deeply notched, articulates 
 with the cricoid cartilage, and is terminated by two processes : one posterior and exter- 
 nal (/), which gives attachment to the lateral and posterior crico-arytenoid muscles ; the 
 other is anterior (a), pyramidal, and more or less elongated, has the inferior vocal cord 
 attached to its point, and it forms a fourth, or almost a third, of the antero-posterior di- 
 ameter of the glottis ; their apex is surmounted, or rather formed, by two very small and 
 delicate cartilaginous nodules (g), which are bent inward and backward, and iiicurvated 
 so that they almost touch ; they are called the cornicula. They were very correctly descri- 
 bed by Santorini, under the name of the sixth and seventh cartilages of the larynx. They 
 are now generally known as the tubercles of Santorini, the capitula or cornicula laryngis. 
 They appear to me constantly to exist, sometimes closely united with the arytenoid carti- 
 lages, and not moving at all upon them, and sometimes perfectly distinct and very movable. 
 
 The Epiglottis. — The epiglottis (em, upon, and yluTrlg, the glottis, i,figs. 174 to 178), 
 or lingula, forming a movable and highly elastic valve, is a fibro-cartilaginous lamina, 
 situated (i, fig. 140) behind the base of the tongue, and in front of the superior opening 
 of the larynx, not upon the glottis, as its name would seem to indicate. 
 
 * It was for a long time believed that there existed only one arytenoid cartilage, because the larynx was al- 
 ways examined when covered by its membranes ; so that the word arytenoid, in the works of Galen, is always 
 applied to the two united, Galen only admitted three cartilages in the larynx— the thyroid, the cricoid, and 
 the arytenoid, . 
 
^^r 
 
 THE LARYNX. 42^ 
 
 Its direction is vertical, excepting at the moment of deglutition, when it becomes hori- 
 zontal, so as to protect the opening of the larynx like a lid {laryngis operculum). Its tri- 
 angular shape has been well compared to that of a leaf of purslaine. It must be separa- 
 ted from the neighbouring parts to be properly studied. 
 
 It varies much in size in different subjects, but always appears to me to bear some re- 
 lation to the dimensions of the upper orifice of the larynx, beyond which it almost al- 
 ways projects when depressed. 
 
 Its anterior or lingual surface presents a free and an adherent portion. The free por- 
 tion surmounts the base of the tongue ; it may be felt by the finger, and even seen by 
 strongly depressing the tongue.* Three folds of mucous membrane, one in the middle 
 and one on each side, pass from the epiglottis to the base of the tongue. 
 
 The adherent portion corresponds in front with the base of the tongue, the os hyoides, 
 and the thyroid cartilage. In order to expose it, it is necessary to have recourse to dis- 
 section. We then find a median glosso-epiglottid ligament, which is very strong, and com- 
 posed of yellow elastic tissue, and which, I beheve, assists in drawing back the depress- 
 ed epiglottis ; its place is occupied by muscular fibres in the larger animals ; also a hyo- 
 epiglottid ligament, extending from the epiglottis to the posterior surface of the os hy- 
 oides ; and, lastly, beneath this ligament, a yellow fatty tissue, improperly called the 
 epiglottid gland, occupying the interval between the epiglottis and the concavity of the 
 thryoid cartilage. 
 
 Moreover, the anterior surface of the epiglottis, examined in the vertical direction, is 
 concave above, convex in the middle, and again concave below ; it is convex in the trans- 
 verse direction. The posterior or laryngeal surface {figs. 175, 178), the curvatures of 
 which are the reverse of those on the anterior surface, is free in the whole of its extent, 
 and covered by the laryngeal mucous membrane. 
 
 Circumference. — Its upper margin, or the base of the triangle which it represents, is 
 free, bent forward, slightly notched, and continuous, by two rounded angles, with its lat- 
 eral margins, from each of which proceed two folds, viz., the aryteno-epiglottid {h,fig. 
 178), extending from the epiglottis to the arytenoid cartilage, and enclosing a ligament 
 (b,fig. 176), and the pharyngeo-epiglottid, situated anterior to the preceding, passing al- 
 most transversely outward, and lost upon the sides of the pharynx. 
 
 The epiglottis terminates below in a sort of pedicle, which is extremely slender, and 
 is fixed {fig. 176) into the retreating angle of the thyroid cartilage, immediately above 
 the attachment of the vocal cords. This attachment is effected by means of a ligament, 
 called the thyro-epiglottid. 
 
 The epiglottis is remarkable for the great number of perforations found in it, which 
 give it an appearance very much resembling that of the leaves of several of the lauracece. 
 In these foramina we find small glands, which, for the most part, open on the laryngeal 
 surface of the epiglottis. The so-called epiglottid gland has no relation with these orifices. 
 
 It is also remarkable for its flexibility and elasticity ; on account of which it is classed 
 by Bichat among the fibro-cartilages, a sort of tissue which we have stated does not ex- 
 ist. Its yellow colour gives it an appearance like the yellow elastic tissue. It is brittle, 
 and may be crushed between the fingers ; this depends partly upon the nature of its tis- 
 sue, and partly upon the numerous foramina with which it is perforated, and which ne- 
 cessarily diminish its strength. 
 
 The Artictdations and Ligaments of the Larynx. 
 
 The articulations of the larynx may be divided into the extrinsic and the intrinsic. 
 
 The Extrinsic Articulations. — The thyro-hyoid articulation consists of three ligaments, 
 which unite the thyroid cartilage to the os hyoides. The middle jy.. 174. 
 
 thyro-hyoid ligament {n, fig. 174) is a loose yellowish membrane, ex- 
 tending from the upper border of the thyroid cartilage {t) to the os 
 hyoides (m). Its vertical dimensions are much greater at the sides 
 than in the middle ; and, therefore, the comua of the os hyoides 
 can be raised higher than its body, and hence the sides of the tongue 
 can be elevated so as to form a groove, along which the food glides. 
 This membrane is thick in the middle, and thin, and, as it were, 
 cellular on each side. 
 
 Relations. — It is sub-cutaneous in the middle, but is covered on 
 each side by the thyro-hyoid muscle. It corresponds behind with 
 the epiglottis, from which it is separated by some adipose tissue, 
 and with the mucous membrane covering the posterior surface of 
 the tongue. It is attached to the posterior lip of the upper edge 
 of the OS hyoides, not to the lower edge, as is frequently asserted. 
 It therefore passes behind the os hyoides. 
 
 The lateral thyro-hyoid ligaments (0) may be considered as the margins of the thyro- 
 hyoid membrane. They are small cords, extending from the great comua of the thyroid 
 
 * I attach groat importance to inspection of the epiglottis in diseases of the larynx. 
 Hb H 
 
^88 8PLANCHN0L0GT. 
 
 cartflage to the tubercular extremities of the great comua of the os hyoidea. We often 
 find a cartilaginous or bony nodule in these ligaments. 
 
 There is a very distinct synovial capsule between the posterior surface of the body of 
 the OS hyoides and the upper part of the thyroid cartilage. Its presence attests the fre- 
 quent movements which take place between these parts, and during which the middle 
 and upper part of the cartilage is placed behind the os hyoides. 
 
 The Tracheo-cricoid Articulation. — The first ring of the trachea is connected with the 
 lower border of the cricoid cartilage by a fibrous membrane of the same nature as that 
 between the rings of the trachea. A small vertical fibrous cord is added to it in the 
 median line in front. This membrane permits some movements between the cricoid 
 cartilage and the first ring of the trachea, and in these the sides of the ring are buried 
 behind the cricoid cartilage. 
 
 The intrinsic articulations are the crico-thyroid and the crico-arytenoid. I need merely 
 remind the reader of the articulation between the arytenoid cartilages and the comicula 
 larjTigis. 
 
 Tlie Crico-thyroid Articulations. — ^These are arthrodial. Each of the lesser comua of 
 the thyroid cartilage terminate in a plane surface, directed downward and inward, which 
 rests upon a similar plane surface {m,fig. 177) on the cricoid cartilage, directed upward 
 and outward. An orbicular or capsular ligament (r,figs. 174, 175), composed of shining, 
 fasciculated, and parallel fibres, surrounds the articulation, which is provided with a 
 synovial membrane. The posterior fasciculus is remarkable for its length and shape, 
 and extends nearly to the crico-arytenoid articulation. In some subjects the orbicular 
 ligament is very loose, in others the articulation is exceedingly close. 
 
 The movements are limited to simple gliding, combined with a forward and backward 
 movement of the th3Toid cartilage. The direction of the facettes upon the cricoid car- 
 tilage renders them fitted to support the thyroid. 
 
 The Crico-thyroid Membrane, or Middle Crico-thyroid Ligament. — Besides the preceding 
 articulations, the lower border of the thyroid cartilage is connected with the upper border 
 of the cricoid by a thick triangular membrane, the pyramidal or conoid ligament (v, Jig. 
 174), which is attached in the median line to the lower border of the thyroid cartilage, 
 and the base of which is fixed to the upper border of the cricoid cartilage. This mem- 
 brane is fibrous, thick, very strong, perforated with foramina for vessels, and is yellow 
 and elastic. 
 
 The Lateral Crico-thyroid Ligament. — This ligament {d,fig. 176) can be well seen 
 only from the inner surface of the larjoix. It consists of very strong fibres, which arise 
 from the inner lip of the upper border of the cricoid cartilage, in front of the crico-ary- 
 tenoid articulation, and pass horizontally inward to the retreating angle of the thyroid 
 cartilage, below the insertion of the inferior vocal cord (r). This ligament, which is very 
 strong, appears to be continuous above with the inferior vocal cord. It is covered on 
 the inside by the mucous membrane of the larynx, and it corresponds on the outside {d, 
 fig. 177) to the thyro- (e) and crico-arytenoid (/) muscles, which separate it from the 
 thyroid cartilage. 
 The Crico-arytenotd Articulations. — These articulations are effected by mutual reception. 
 The articular swr/ace, upon the cricoid cartilage, is an eUiptical facette {h,fig. 173), di- 
 rected obliquely downward and forward, and oblong and slightly concave in the same di- 
 rection. The base of the arytenoid cartilage presents an oblong articular facette, deeply 
 concave from without inward, i. c, in an opposite direction to the former, which it accu- 
 rately receives. 
 Means of Union. — Properly speaking, there is only one ligsunent, the internal and poste- 
 j^. ,.- rior (e, fig. 175). It arises from the cricoid cartilage, and is insert- 
 
 ^' ' • ed in a radiated manner into the inner and back part of the base of 
 
 the arytenoid cartilage, and to the inner side of its anterior process, 
 behind the inferior vocal cord. This ligament is very strong, but 
 yet suiEciently loose to allow of certain extensive movements. 
 There is also a very loose synovial capsule, which can be easily 
 demonstrated. 
 
 The movements of this articulation, like those of all similar joints, 
 take place in every direction ; but the movements inward and out- 
 ward are much more extensive than those which are performed 
 forward and backward. On account of the mode of insertion of its 
 muscles, the arytenoid cartilage is not moved in a direct line, but 
 undergoes a partial rotatory movement, the centre of which is in 
 the articulation. In the movement, which is oblique, on account 
 of the obliquity of the articular surfaces, the apex of the arytenoid 
 cartilage is carried either outward and backward or inward and for- 
 ward. These motions should be studied with the greater care, because they afford an ex- 
 planation of the changes which take place in the glottis during the production of the voice. 
 The Aryteno-epiglottid Ligament. — This ligament {b, figs. 176, 177) is constituted by 
 some radiated ligamentous fibres contained within the aryteno-epiglottid fold of mucous 
 
THE LARYNX. 427 
 
 membrane, and which pass from the anterior surface of the arytenoid cartilage to the 
 corresponding margin of the epiglottis. In some animals, this ligament is replaced by 
 muscular fibres. 
 
 The Thyro-arytenoid Ligaments, or Chorda Vocales. — Although there is no immediate 
 relation between the thyroid and the arytenoid cartilages, they are united by four very 
 important ligaments, named the chorda vocales, which require a special description. 
 
 The chorda vocales are also called the vocal bands, the ligaments of Ferrein, or the thy- 
 ro-arytenoid ligaments, because tliey have a ligamentous appearance, and extend from 
 the retreating angle of the thyroid cartilage to the arytenoid cartilages. 
 
 There are two vocal cords on each side, a superior (s, Jigs. 176, 178) and an inferior (r) , 
 the space between them is called the ventricle of the larynx (v), and the interval between 
 the cords of the right and left sides is called the glottis {o,Jig. 178).* I shall speak of 
 these parts again presently. 
 
 The inferior vocal cord (r, Jig. 176) is much stronger than the superior, and has the form 
 of a rounded fibrous cord, stretched horizontally from the retreating y. j^g 
 
 angle of the thjToid cartilage to the anterior process of the arytenoid 
 cartilage. It is free in all directions, excepting on the outside, where 
 it is in contact with the thyro-arytenoid muscle. Its free portion is 
 covered by the mucous membrane of the larynx, which adheres inti- 
 mately to it, and is so thin that the white colour of the cord can be 
 seen through it. This vocal cord is thinner than it appears at first 
 sight, the projection which it forms being, in a great measure, due 
 to the thyro-arytenoid muscle. Its structure is entirely ligamentous, 
 and consists of parallel fibres, running from before backward, and not 
 at all elastic, t 
 
 It is continuous below with the lateral thjrro-cricoid ligament (d). 
 
 The superior vocal cord (s) is smaller, and situated farther from the 
 axis of the larynx than the inferior one (see Jig. 178), and extends 
 from the middle of the retreating angle of the thyroid cartilage to the 
 middle of the anterior surface of the arytenoid cartilage : like the inferior cord, it has a 
 fasciculated and fibrous appearance ; but the fasciculi are few in number, and are inter- 
 mixed with a series of glandular masses. The superior vocal cord can only be distin- 
 guished from the rest of the parietes of the laiynx from the reflection of the mucous 
 membrane below it, so as to form the ventricle. It is continuous with the aryteno-epi- 
 glottid ligament (Jb, Jig. 176) above, without any line of demarcation. 
 
 Muscles of the Larynx. 
 
 These are divided into the extrinsic and the intrinsic : the former, which move the en- 
 tire larynx, have been already described, viz., the sterno-hyoid, omo-hyoid, stemo-th)Toid, 
 and thyro-hyoid ; to which we might add all the muscles of the supra-hyoid region, and 
 those muscles of the pharynx which have attachments to the cricoid and thyroid cartilages. 
 
 The intrinsic muscles are nine in number, viz., four pairs and one single muscle. 
 Those which exist in pairs are the crico-thyroidei, the crico-arytenoidei postici, the cri- 
 co-arytenoidei laterales, and the thyro-arytenoidei. The single muscle is the arjrtenoideus. 
 
 The Crico-thyroideus. 
 
 . Dissection. — This muscle is completely exposed by separating the larynx from the 
 muscles by which it is covered. In order to gain a good view of the deep portion of the 
 muscle, the lower part of the thyroid cartilage must be removed. 
 
 The crico-thyroideus {a, figs. 147, 170) is a short, thick, triangular muscle, situated on 
 the anterior part of the larynx, on each side of the crico-thyroid membrane, and divided 
 into two distinct bundles. It is attached below to the cricoid cartilage on each side of 
 the median line, to the whole of the anterior surface, and even to part of the lower bor- 
 der of the cartilage. From these points the fleshy fibres radiate in different directions : 
 the internal fibres pass somewhat obliquely upward and outward ; the middle ones very 
 obliquely, and the lower fibres horizontally outward, to the lower border of the thyroid 
 cartilage (excepting to its middle portion), and to the lower margin of the corresponding 
 lesser cornu. The greatest number of fibres are inserted into the posterior surface of 
 the thyroid cartilage ; some of them are continuous with the inferior constrictor of the 
 pharynx (w, Jig. 147). 
 
 It is covered by the sterno-thyroid muscle and the thyroid gland, and it covers the lat- 
 eral crico-arytenoid and the thyro-arytenoid muscles. The inner borders of the crico- 
 thyroid muscles are separated from each other by a triangular space, broad above and 
 narrow below, in which the crico-thyroid membrane is visible. 
 
 * [In consequence of the voice being essentially produced opposite the inferior cords, they are termed the 
 true vocal cords ; the superior being- called the false vocal cords.] 
 
 t [The inferior vocal cords are certainly composed of elastic tissue, so, also, are the thyro-hyoid and crico- 
 thyroid ligaments ; and, according to M. I.auth (M'm. de VAcad. Roy. de Med., 1835), the lateral crico-thyroid 
 membranes, the superior vocal cords, and the aryteno-epiglottid ligaments are also composed of this tissue, 
 which, he says, exists even in the thyro-epiglottid, hyo-epiglottid, and glosso-epiglottid ligaments.] 
 
428 SPLANCHNOLOGY. 
 
 Their action is not yet well determined. By taking theif'feed'pmnfuponthe' cricoid 
 
 cartilage, it appears to me that they would move the thyroid cartilage in such a way as 
 to increase the antero-posterior diameter of the glottis, and thus act as tensors of the 
 vocal cords. 
 
 The Crico-arytenoideus Posticus. 
 
 Dissection. — This muscle is exposed by removing the mucous membrane from the 
 posterior surface of the larynx. 
 
 It is a triangular muscle {g,figs. 171, 177), situated at the back of the cricoid carti- 
 lage. Its fibres arise from the lateral depression, which we have described on tlie pos- 
 terior surface of the cartilage, and pass in different directions ; the upper fibres are the 
 shortest, and are almost horizontal ; the middle are oblique, and the lower are nearly 
 vertical ; they £dl converge towards the posterior and external process on the base of 
 the arytenoid cartilage, behind the crico-arytenoideus lateralis. 
 
 Relations. — It is covered by the mucous membrane of the pharynx, to which it is very 
 loosely united, and it covers the cricoid cartilage. 
 
 Action. — It is a dilator of the glottis. It carries the base of the arytenoid cartilage 
 backward, outward, and downward, and thus renders the inferior vocal cord tense 
 
 The Crico-arytenoideus Lateralis. 
 Fig. 177. Dissection. — Remove with care one of the lateral halves of the 
 
 thyroid cartilage (as in fig. 177). It is impossible to separate this 
 muscle from the thyro-arytenoideus. 
 
 This is an oblong muscle (/), situated deeply under the thyroid 
 cartilage. Its fibres arise from the side of the upper border of the 
 cricoid cartilage, in front of the crico-arytenoid articulation ; from 
 this point they proceed obliquely upward and backward, to be insert 
 ed into the posterior and external process of the arytenoid cartilage, 
 by a tendon common to them, and to the thyro-arytenoideus. It is 
 covered by the thyroid cartilage and by the crico-thyroid muscle, and 
 it covers the lateral crico-thyroid membrane (d). 
 
 The Thyro-arytenoideus. 
 Dissection. — The same as for the preceding. This muscle may be 
 dissected from the interior of the larynx, by removing the vocal cords. 
 
 I describe the thyro-arytenoideus and the crico-arytenoideus lateralis separately, 
 merely in accordance with custom, for in no instance, not even in large animals, such 
 as the ox, have I ever been able to separate them completely. They have the same 
 arytenoid insertion ; their fibres are situated upon the same plane, without any line of 
 demarcation, and they fulfil the same uses. We naight, therefore, imite them under the 
 name of the thyro-crico-arytenoideus. 
 
 The thyro-arytenoideus (e) is a broad muscle, very thin above and very thick be- 
 low. It arises on each side from about the lower two thirds of the retreating angle of 
 the thyroid cartilage. The greater number of its fibres arise from the lower part of the 
 angle, and form a very thick fasciculus. From these points they pass horizontally back- 
 ward and outward, and terminate in the following manner : The thick fasciculus above 
 mentioned is inserted into the outer surface of the anterior process of the arytenoid car- 
 tilage, and into a depression on the outer side of the base of that cartilage, between the 
 two processes. The upper fibres are attached to the outer border of the arytenoid car- 
 tilage. In the larger animals, the upper fibres of the muscle evidently proceed to the 
 epiglottis, and form the thyro-epiglottideus of some authors. 
 
 Relations. — On the outside it corresponds with the thyroid cartilage, from which it is 
 separated by loose and sometimes adipose cellular tissue ; on the inside it is in contact 
 with the vocal cords and the ventricle of the larynx. The thickest part of the muscle 
 corresponds with the inferior vocal cord, and is almost the only cause of its projecting 
 into the interior of the larynx. This fasciculus may even be considered as contained 
 within the substance of the inferior vocal cord, and the two structures are so closely 
 adherent that great care is required to separate them. Many anatomists, indeed, have 
 thought that the fibres of the thyro-arytenoideus terminate in the vocal cord, which they 
 therefore regarded as the tendon of the muscle ; but the cord and muscle may always be 
 completely separated. 
 
 Action. — It carries the arytenoid cartilage forward, and would thus seem to relax the 
 inferior vocal cord, as Haller believed : " Cartilagines guttales (the arytenoid) antrosum 
 ducunt, glottidem dilatant, ligamentorum glottidis tensionem minuunt." {Elemcnta Physiol., 
 t. iii., liv. ix., p. 387.) But if we consider the mechanism of the crico-arytenoid articula- 
 tions, and the mode of insertion of the thyro-arytenoid muscles into the outer side of 
 the bases of the arytenoid cartilages, we shall perceive that, at the same time that these 
 cartilages are carried forward, they undergo a partial rotatory movement, by which their 
 anterior processes are turned inward. The ligaments of the glottis are, therefore, ren- 
 
THE LARYNX. 429 
 
 dered tense, and approximated towards each other. This movement may be carried to 
 such an extent that the anterior processes may touch, and the antero-posterior diameter 
 of the glottis be diminished accordingly.* 
 
 The thyro-arytenoideus is, then, both a tensor and a constrictor of the glottis. This, 
 moreover, was the opinion of both Cowper and Albinus, but Hedler attempted to re- 
 fute it.t 
 
 The sudden action of the thyro-arytenoid muscle, pressing upon the ventricle of the 
 larynx, may expel any mucus collected within it. 
 
 The Arytenoideus. 
 
 Dissection. — Remove the mucous membrane and glandular masses which cover it be- 
 hind. Detach it along one of its borders, so as to be enabled to examine its thickness. 
 
 The arytenoideus {a, fig. 171) is a single, short, thick, trapezoid muscle, situated be- 
 hind the arytenoid cartilages, and filling up the concavity on their posterior surfaces, as 
 well as the interval between them. It arises from the whole length of the outer border 
 of the right arytenoid cartilage, and is inserted into the corresponding part of the left. 
 Some of the fibres arise from the upper border of the cricoid cartilage. The fibres have 
 a triple direction, and form three layers, which have been regarded as so many distinct 
 muscles. 
 
 The two more superficial layers are oblique, and cross each other, one passing from 
 the base of the right arytenoid cartilage to the apex of the left, and the other following 
 the opposite direction ; they constitute the arytenoideus ohliquus of Albinus : both of these 
 layers are thin. 
 
 The third and deepest layer is very thick ; it is composed of transverse fibres, and 
 forms the arytenoideus transversus of Albinus. 
 
 None of the fibres reach the comicula. Under the name of the aryteno-epiglottideus, 
 muscular fibres have been described, extending from the arytenoid muscle to the mar- 
 gins of the epiglottis. Some fibres of the arytenoideus are also said to be continuous 
 with the thyro-arytenoideus. 
 
 Relations. — Behind, with the mucous membrane and some glandular masses, which ad- 
 here to the muscle by means of loose cellular tissue ; in front it is in relation with the 
 posterior surface of the arytenoid cartilages, and in the interval between them with a 
 thin fibrous membrane, extending from the upper border of the cricoid cartilage to the 
 whole extent of the inner borders of the arytenoid cartilages. 
 
 Action. — It would appear, at first sight, that this muscle must forcibly approximate the 
 two arytenoid cartilages, and therefore constrict the glottis ;t but if we remember that 
 it is attached to the outer borders of these cartilages, we shall understand that, besides 
 drawing them together, it must produce in them such a movement as will carry their an- 
 terior processes outward, and stretch the vocal cords, but, at the same time, separate them 
 from each other. And if we call to mind that the th3TO-arytenoideus occasions an ex- 
 actly opposite movement, it will be understood that the simultaneous action of the two 
 muscles must produce tension of the cords, and, at the same time, fix the processes. 
 
 Having thus obtained a knowledge of the cartilages of the larynx, the articulations by 
 which they are united, and the muscles which move them, we shall now proceed to give 
 a general description of this organ. 
 
 The Larynx in general. 
 
 The larynx, the general position of which has been already described, presents certain 
 diflferences in its dimensions, depending either upon the individual, upon sex, or upon age. 
 These differences affect both the whole of the larynx and its constituent parts. Thus, 
 the larynx of the female may always be distinguished from that of the male by being 
 smaller, i. e., about two thirds the size of the male larynx ; and by the angles and pro- 
 cesses of its cartilages being less prominent, and their depressions less marked. These 
 differences are connected with the characters of the voice, and affect principally the di- 
 mensions of the glottis. 
 
 The individual differences in the size of the larynx have not been thoroughly examined. 
 The differences depending on age will be noticed when speaking of its development. 
 
 The larynx presents for our consideration an external and an internal surface. 
 
 The External Surface of the Larynx — Anterior Region {fig. 170). — In the median line we 
 observe a vertical ridge, formed by the angle of the thyroid cartilage ; beneath this the 
 crico-thyroid membrane, and still lower the convexity of the cricoid cartilage. 
 
 On the sides we find the oblique leuninae of the thyroid cartilage, a portion of the cri- 
 coid covered by the crico-thyroid muscle, and the thyro-cricoid articulation. 
 
 Sub-cutaneous in the median line, where it is only separated from the skin by the linea 
 alba of the neck, the external surface of the larynx is covered on each side by the mus- 
 cles of the sub-hyoid region, the inferior constrictor of the pharynx, and the thyroid gland. 
 
 * [The effect of this will be, as stated by Haller, to relax the vocal cords, which is considered by the latest 
 observers to be the action of these muscles.] 
 
 ■t Loc. cit. " Cum magui viri glottidem dixerint ab istis musculis arctari, experimento facto diducere didici. 
 Neque potest ille ad latus cartilaginis arytsenoidse musculus terminari xjuin earn rimam diducat." 
 
 t [When acting together with the lateral crico-thyroid muscles, this is certainly their action.] 
 
430 SPLANCHNOLOGY. 
 
 The superficial position of the surface enables us to examine its different parts through 
 the integuments, and renders it liable to wounds. Its still greater proximity to the skin 
 in the median line has suggested the operation of laiyngotomy. 
 
 Posterior Region {figs. 141, 171). — In the median line we observe a prominence like a 
 small barrel, on either side of which the thyroid cartilage projects. This prominence is 
 formed by the back of the cricoid, and by the arytenoid cartilages, the expanded portion 
 corresponding with the bases of the latter, which are covered by folds of a pale mucous 
 membrane. Under this membrane we find, proceeding from above downward, the ary- 
 tenoideus muscle, the vertical ridge of the cricoid cartilage, the crico-arytenoidei posti- 
 ci, and the crico-arytenoid articulations. 
 
 On each side of the barrel-shaped prominence is a deep angular groove, formed by the 
 meeting of two flat surfaces, which are separated above, but approximated below ; along 
 these grooves it is supposed that liquids flow during deglutition. The external wall of 
 each groove is formed by the posterior surface of the thyroid cartilage, the os hyoides, 
 and the thyro-hyoid membrane. The internal wall is formed by the upper and lateral part 
 of the barrel-shaped prominence. The grooves are lined by a closely-adherent nmcous 
 membrane ; and it should be observed, that they exist only on a level with the aryte- 
 noid cartilages, and, consequently, in this region alone is the larynx protected by the 
 thyroid cartSage, the posterior borders of which rest upon the vertebral column. The 
 back of the cricoid cartilage is on a level with the posterior borders of the thyroid {fig. 
 174), and, like them, rests upon the vertebral colunm. 
 
 The Internal Surface of the Larynx. — The internal surface of the larynx does not cor- 
 respond, either in shape or dimensions, with its outer surface ; and this depends princi- 
 pally on the fact that the retreating angle of the th)T:oid is the only part of that cartilage 
 which enters into the formation of the laryngeal cavity, the lateral laminae being alto- 
 gether unconcerned in it. 
 
 Cylindrical below, where it is formed by the cricoid cartilage, the cavity of the larynx 
 is prismatic and triangular above, where it is constituted by the epiglottis in front, the 
 arytenoid cartilages and the arjrtenoid muscle behind, and on the sides by the two mu- 
 cous folds which extend from the margins of the epiglottis to the arytenoid cartilages. 
 The dimensions of the lower of these two portions of the laryngeal cavity undergo no 
 change, always remaining the same as those of the cricoid cartilage ; while the upper, 
 on the contrary, which is broadest in front, varies much in size, in consequence of the 
 mobility of the epiglottis and the arytenoid cartilages. Between these two portions, and 
 about the middle of the larynx, a fissure exists, which is narrower than the rest of the 
 cavity, and oblong from before backward ; this is the glottis, or vocal apparatus, properly 
 so called. It can be seen without any dissection by looking down into the larynx {fig. 
 178), and requires a very particular description. 
 
 The Glottis, or Vocal Apparatus. — The glottis (yXwrrif, from y^uaaT), the tongue), fre- 
 quently confounded with the superior orifice of the larynx,* is a trian- 
 gular opening or fissure {o,fig. 178) {rima), elongated from before 
 backward, and included between the vocal cords of the right and 
 left sides. It represents two isosceles triangles, placed one above 
 the other, and having perfectly equal borders, the base of each being 
 directed backward, and its apex forward. The lower isosceles tri- 
 angle is formed by the inferior vocal cords (r), and the upper one by 
 the superior vocal cords (s). The inferior vocal cords are situated 
 nearer to the axis of the larynx than the superior, so that a vertical 
 plane let fall from the latter would leave the inferior vocal cords on 
 its inner side. Many authors limit the term glottis to the lower tri- 
 angle. This view is supported by the absence of the superior vo- 
 cal cords in a great number of animals, the ox in particular. 
 
 Dimensions of the Glottis. — The glottis is the narrowest part of the larynx, and hence 
 the danger from the introduction of a foreign body into it, and from the formation of false 
 membranes in this situation. The only action of the intrinsic muscles of the larynx is 
 to dilate or contract the opening of the glottis. We have seen that, with the exception 
 of the crico-thyroidei, they are all, in some measure, collected round the crico-arytenoid 
 articulation, the movements of which determine the dimensions of the glottis. 
 
 The individual differences which constitute the tenour, baritone, or bass voices in sing- 
 ing, depend upon the size of the glottis ; to which, also, must be attributed the difference 
 between the male and female voice, and the change produced in its tone at the time of 
 puberty. A deep voice coincides with a large glottis, and a shrill voice with a small one. 
 In the adult male the antero-posterior diameter of the glottis is from ten to eleven lines, 
 in the female it is only eight lines ; in the male, the greatest transverse diameter is from 
 three to four lines ; in the female, from two to three lines. t 
 
 * This error is, perhaps, to be attributed to the use of the word epiglottis, so much do words influence our 
 ideas. It was committed even in Haller's time, who says, " Etiam hoc (laryngis) ostktm non bene pro glottide 
 sumilur." 
 
 t Tliese measurements are taken at the level of the inferior vocal cords ; the transverse diameter is rather 
 l(!i:L'er opposite the superior vocal cords 
 
THE LARYNX. 431 
 
 From these dimensions, it may be understood how a Louis d'or might pass edgewise 
 through the glottis, and thus fall into the trachea. In a case of this kind, most of those 
 ■who were called in consultation rejected the idea of the presence of the coin in the wind- 
 pipe, because, said they, the glottis cannot admit it. The patient died in about a year, 
 and the Louis d'or was found in the trachea. 
 
 Ventricle of the Larynx. — Between the superior and inferior vocal cords of each siile 
 there is a cavity, called the ventricle or simis of the larynx {v,figs. 176, 178) ; it is oblong 
 from before backward, and of the same length as the cords ; its depth is determined by 
 the interval separating the cords from the thjToid cartilage, or, rather, from the thyro- 
 arytenoid muscle, which forms the bottom of the corresponding ventricle. The opening 
 of the ventricle is somewhat narrower than the bottom, is elliptical in its longest diame- 
 ter, and has admitted the introduction of a foreign body. To each ventricle there is a 
 supplementary cavity, which is accurately described and figured in the works of Mor- 
 gagni.* This cavity resembles in shape a Phrygian cap ; it has a broad base, opening 
 into the ventricle, and a narrow apex ; it is found at the anterior part of the ventricle, 
 and is prolonged on the outer side of the superior vocal cord, between it and the thyroid 
 cartilage, upon the side of the epiglottis. Its dimensions vary much. In one case its ver- 
 tical diameter was six lines, and it was divided into two parts by a transverse band. 
 
 The Circumferences of the Larynx. — The superior circumference of the larynx {fg. 178) 
 is much wider than the inferior, and presents the following objects : the superior angu- 
 lar border of the thyroid cartilage, and the great cornua, in which it terminates ; behind 
 the thjToid cartilage, the epiglottis (i) ; and between the cartilage and the epiglottis, a 
 small triangular space, filled by a compact fatty mass, which has been incorrectly descri- 
 bed as the epiglottid gland. I have already said that this fatty mass is bounded above by a 
 fibrous membrane, extending from the epiglottis to the posterior surface of the os hyoides. 
 
 Behind the epiglottis, we find the upper orifice of the larynx, which must not be con- 
 founded with the glottis ; it slopes obliquely from before backward and from above down- 
 ward, having the form of a triangle, with its base directed forward and its apex back- 
 ward, consequently in the opposite direction to the glottis. This orifice is formed in 
 front by the free margin of the epiglottis, which is slightly notched ; on each side, by the 
 upper part of the lateral margin of the epiglottis, and by the free edge of the aryteno- 
 epiglottid fold (b) ; and behind, by the cornicula laryngis, and by the summits of the ary- 
 tenoid cartilages (a), and the deep notch between them. 
 
 The superior orifice is the widest part of the larynx, and admits foreign bodies which 
 cannot pass through its lower portion. The epiglottis, when depressed, generally cov- 
 ers it completely, and may even overlap it at the sides. 
 
 The inferior circumference of the larynx is perfectly circular, is formed by the cricoid 
 cartilage, and is continuous with the trachea. 
 
 The Mucous Membrane and Glands of the Larynx. — The mucous membrane of the la- 
 rynx is a continuation of that of the mouth and pharynx. The larynx presents the only 
 example in the body of an organ, part of whose external surface, namely, the posterior, 
 is covered with mucous membrane ; and this depends upon the circiunstance of its form- 
 ing part of the parietes of the pharynx. 
 
 The mucous membrane is disposed in the following manner : From the base of the 
 tongue it i& reflected upon the anterior surface of the epiglottis, forming the three glos- 
 so-epiglottid folds already described, one in the middle and one on each side ; it adheres 
 pretty closely to the epiglottis, is reflected over its free margin, covers its posterior s«r- 
 face, and penetrates into the larynx : on each side it passes from the epiglottis to the 
 •arytenoid cartilages, and becomes continuous with the pharyngeal mucous membrane, 
 which covers the back of the larynx. At the superior orifice of the larynx, it is reflect- 
 ed upon itself, to form the aryteno-epiglottid folds, which constitute the sides of the su- 
 pra-glottid region of the larynx ; it then covers the superior vocal cord, and lines the ven- 
 tricle, sending a prolongation into its supplementary cavity. In the ventricle it is re- 
 markable for its slight adhesion to the subjacent parts. It is reflected from the ventri- 
 cle upon the inferior vocal cord ; there, as well as opposite the superior cord, it is so 
 thin that it does not conceal the pearly appearance of the ligament beneath, to which it 
 adheres so closely that it is difficult to separate them. Lastly, it covers the internal sur- 
 face of the cricoid cartilage, and the middle and lateral crico-th)Toid membranes. 
 
 The laryngeal mucous membrane is characterized by its tenuity, its adhesion to the 
 parts heneath it, and by its pale pink colour.! It is perforated by the openings of a num- 
 ber of mucous glands. Its extreme sensibility, especially at the upper orifice and in the 
 
 * I first saw this cavity in a patient affected with laryngeal phthisis, in whom it was very much developed. 
 I then examined the larynx in other individuals, and found it to be constant. I did not then know that Mor 
 gagni had pointed it out and figured it (Advers. i., Epist. Anat., viii.). 
 
 t [The epithelium of the laryngeal mucous membrane is, in the greater part of its extent, columnar and cil 
 iated. The cilia urge the secretion upward ; according to Dr. Henle, they extend higher up in front than on 
 each side and behind ; on the sides, for example, as high as the border of the superior vocal cords, or about 
 two lines above them, and in front upon the posterior surface of the epiglottis, as high as its base or widest por- 
 tion. Above these points the epithelium gradually assumes the laminated form, like that in the mouth and 
 pharynx.] 
 
432 SPLANCHNOLOGY. 
 
 supra-glottid portion of the larynx, is well known.* The aryteno-epiglottid folds, which 
 include the ligaments of the same name, and some muscular fibres in the larger animals, 
 aie remarkable for the great quantity of very loose cellular tissue which they contain : 
 this fact explains their liability to a serous infiltration, called oedema of the glottis, which 
 proves rapidly fatal. 
 
 The Glands of the Larynx. — The glands of the larynx are the epiglottid and the aryte- 
 noid. The thyroid gland, or body, cannot be considered as belonging to the larynx ; if 
 it belongs to any organ, it must be to the trachea. 
 
 The Epiglottid Glands. — The name of epiglottid glands is generally given to the fatty 
 mass already described as being situated between the thyroid cartilage and the epiglot- 
 tis ; and it has even been asserted that it opens by special ducts on the posterior surface 
 of the epiglottis. But there is no other epiglottid gland besides those situated in the sub- 
 stance of the epiglottis, which is perforated with innumerable holes for their reception : 
 these small glands are so numerous, that Morgagni (^Advers., i., 2 ; v., 68) regarded them 
 as forming a single gland ; they all open upon the laryngeal surface of the epiglottis by 
 very distuict orifices, from which a considerable quantity of mucus can be pressed. 
 
 The Arytenoid Glands. — These were well described by Morgagni, who very properly 
 considered them as forming a single glandular mass, situated in the substance of the ary- 
 teno-epiglottid fold. They are arranged in two lines, united at an angle, like the letter 
 L;t the vertical line runs along the anterior surface of the arytenoid cartilage and its 
 comiculum, and produces a slight prominence, perfectly distinct from that made by the 
 cartilages ; the liorizontal line is less prominent, and is situated in the superior vocal 
 cord. The arytenoid glands open separately upon the internal surface of the larynx. 
 
 Vessels and Nerves. — The arteries are derived from the superior thyroid, a branch of 
 the external carotid, and from the inferior thyroid, a branch of the subclavian. The veins 
 enter the corresponding venous trunks. The lymphatic vessels, which are little known, 
 terminate principally in the glands of the supra-hyoid region, if we may judge from the 
 frequency of their inflammation in cases of acute laryngitis, &c. 
 
 The nerves are branches of the pneumogastric, viz., the superior and the inferior, or 
 recurrent laryngeal. The superior laryngeal nerves are not exclusively distributed to the 
 muscles called constrictors of the glottis (thearytenoideus and the crico-thyroidei) ; nor 
 do the inferior laryngeals belong exclusively to those called dilators (the crico-arytenoi- 
 dei postici and laterales, and the thyro-arytenoidei), as a celebrated physiologist has af- 
 firmed. (See Nkukology. ) The peculiar rotatory movement of the arytenoid cartilages 
 somewhat interferes with any classification of these muscles into dilators and constrictors. 
 Development. — The evolution of the larynx is remarkable in this respect, that, after hav- 
 ing attained a certain size, it undergoes no appreciable change until the time of puberty. 
 The ventricles are as yet so slightly developed that their existence has been denied. The 
 prominence of the os hyoides in some measure conceals that of the larynx. M. Rich- 
 erand {Mem. de la Societe Med. d' Emulation, torn, iii.) has proved that there is no very 
 remarkable difference between the larynx of a child at three years of age and of one at 
 twelve. Up to the age of puberty the larynx presents no trace of the sexual differences 
 which afterward become so evident ; and to these anatomical conditions are owing the 
 shrillness and uniformity of the voice in the youth of both sexes. 
 
 At the period of puberty, at the same time as the genital organs, the larynx increases 
 so rapidly as to attain its full development in the space of one year ; the voice then loses 
 ilj uniformity, and acquires its pecidiar timbre and quality, and then also the sexual dif- 
 ferences in the vocal apparatus become manifest. 
 
 Is it from an unequal development of the different parts of the larynx, or from want 
 of a certain degree of education, that the voice at this period is so discordant, especial- 
 ly in singing, or breaks, as it is said 1 
 
 The simultaneous development of the genital organs and the larynx has led to the opin- 
 ion that they stand to each other in the relation of cause and effect ; and observation 
 has established that the vocal apparatus is in some measure under the influence of the 
 generative organs ; for in eunuchs the larynx remains as small as it is in the female. 
 (M. Dupuytren, Mem de la Soc. Phil., tom. ii.), 
 
 At the age of puberty the size of the glottis is increased by one third in the female, 
 and is nearly doubled in the male. After puberty, any changes which the larynx may 
 undergo are the result of exercise, not of development, properly so called. 
 
 Ossification of the cartilages of the larynx is not always the effect of age. I have seen 
 it at the thirtieth year quite independently of disease. Chronic inflammation of the la- 
 rynx induces a premature ossification of the cartilages. The th)Toid has the greatest 
 tendency to this change, then the cricoid, and, lastly, the arytenoid cartilages : I have 
 never observed it in the epiglottis. 
 
 Functions. — The larynx is the organ of voice. Numerous experiments upon living 
 animals, and many surgical facts, show that the vocal sound is produced exclusively in 
 
 * It has been observed, in experiments upon animals, and in introducing the canula after the operation of 
 laryngotomy, that the sensibility of the mucous membrane beyond the glottis is much less acute, 
 t " Gnomonis, sed obtusanguli figuram utervis acervns habet." — (Haller.) 
 
THE THYROID GLAND. 433 
 
 the larynx. The lungs, the bronchi, and the trachea perform, with regard to the voice, 
 the office of an elastic conductor of air capable of contraction and dilatation, of shorten- 
 ing and elongation. The thorax acts like a pair of bellows, by which the air is driven 
 into the larynx with any wished-for degree of force ; and hence the quantity of air pass- 
 ing through the larynx, and the rapidity with which it moves, may vary to a very great 
 extent. 
 
 What, then, is the mechanism of the voice 1 Is it the same as that of a horn {Dodart), 
 of a stringed instrument {Fcrrein), of a flute ( Cuvier), of a reed instrument {Biot and Mw- 
 gendic), or of a bird-call* (Savart) 1 Is it produced by the vibration of the tense vocal 
 cords, or merely by the vibration of the air while passing through a narrow opening, 
 which is itself incapable of vibrating 1 We shall leave these questions to the decision 
 of physiologists. It is sufficient for our purpose to know that the action of the muscles 
 of the larynx and the arrangement of the vocal apparatus are perfectly fitted to produce 
 either dilatation or contraction of the glottis ; and such is the mechanism of this part, 
 that, from the rotatory movement of the arytenoid cartilages, the vocal cords are always 
 rendered tense, whatever may be the other actions of the muscles. 
 
 The voice as it issues from the larynx is simple, for the larynx is, with regard to the 
 voice, what the mouth-piece is in the flute, or the reed in the bassoon ; but during its pas- 
 sage througli the vocal tube, composed of the epiglottis, the pharynx, the isthmus of the 
 fauces, the mouth, and the nasal fossae, the voice becomes modified. 
 
 According to a very ingenious theory of M. Magendie, the epiglottis resembles those 
 soft; and movable valves which M. Grenie places in the pipes of an organ to enable the 
 sound to be increased without modifying the tone. 
 
 The isthmus of the fauces resembles the superior larynx of birds, which consists of a 
 contractile orifice that can be diminished, and even closed at pleasure ; and it is princi- 
 pally owing to this mechanism that the small glottis of birds can execute such an exten- 
 sive range of notes. We know, in fact, that the tone of a wind instrument is reduced 
 an octave lower by completely closing the lower orifice of the tube, and that, when it is 
 only partially closed, the tone is depressed in proportion. Now the isthmus of the fau- 
 ces acts exactly like the superior larynx of birds. On watching a person who wishes 
 to utter a very low note, we see that he depresses and flexes the head slightly upon the 
 neck, so as to approximate the chin to the thorax : by this means the vertical diameter 
 of the isthmus of the fauces is diminished, the larynx being carried upward, while the 
 velum palati is depressed ; and from this we may judge of the important part performed 
 by the velum in producing modulations of the voice. 
 
 If to this we add the changes which may be effected in the length and diameter of the 
 pharynx (see Pharynx), and if we remember that, by diminishing by one half the length 
 or diameter of the tube or body of a wind instrument, its tone is raised one octave, we 
 shall be able to understand how the human voice can execute so extensive a scale of 
 notes, although the glottis is so small. The voice is also modified while traversing the 
 buccal and nasal cavities. 
 
 Do the nasal fosscr. favour the resonance of the voice 1 or does the air, when passing 
 through them, merely give rise to certain sounds denominated nasal 1 The latter opin- 
 ion, which is supported by Mr. Gerdy, appears to me the most consistent with facts. 
 MM. Biot and Magendie had already correctly observed that the voice becomes nasal 
 only when it traverses these passages. 
 
 The voice becomes articulate in passing through the mouth, i. e., the vocal sound is 
 interrupted, and modified by the more or less rapid percussion of the lips and tongue 
 against the teeth and the palate. 
 
 Articulate voice is very distinct from speech. Animals which differ much from man 
 in the conformation of their vocal organs, the parrot, for example, may be made to artic- 
 ulate ; but speech is the peculiar attribute of man, because he alone is possessed of in- 
 telligence. 
 
 The Thyroid Gland. 
 
 The thyroid gland, or thyroid body, is a glanduliform organ, the uses of wnich are un- 
 known : it is situated like a crescent with its concavity directed upward, in front of the 
 first rings of the trachea, and upon the sides of the larynx. 
 
 In describing this organ in connexion with the larynx, I follow the usual custom, 
 which has arisen not from any direct relation between their functions, but from their 
 contiguity to each other. 
 
 The thyroid body varies much in size in different individuals ; there are few organs 
 which present greater varieties in this respect. 
 
 ^ The sexual differences in the size of this organ, like all those relating to the vocal ap- 
 paratus, are very well marked, but in an inverse manner, that is to say, the thyroid body 
 is larger in the female, in whom it forms a rounded projection, which assists in making 
 the thyroid cartilage in that sex apj)ear still less prominent. 
 
 * A bird-call is a cavity with elastic walls, perforated upon the two opposite sides. Tlie cavity is repre- 
 ■ented by the ventricles, and the openings by the intervals between the vocal cords. If a tube capable of 
 contracting and dilating be fitted to such an instrument, an infinite variety of sounds may be produced. 
 
 I I I 
 
484 SPLANCHNOLOGY. 
 
 Climate, and more especially certain qualities in the water used as drink, have a re- 
 markable influence upon its size, which, in many cases of goitre, is enormous. 
 
 These differences in size affect either the whole of the gland equally, or only one lobe, 
 or occasionally the middle portion alone. 
 
 The iveight of the thyroid body, which is about an ounce, may be increased to a pound 
 and a half, or even more. 
 
 Form. — The thyroid body is generally composed of two lateral lobes or cornua, united 
 by a contracted portion, flattened from before backward, and called the isthmus. Tlie 
 varieties in shape principally affect the isthmus, which may be very narrow, long or 
 short, regular or irregular, or entirely absent, or it may be as thick and as long from 
 above downward as the lobes themselves. I have seen one case in which the thickest 
 part of the thyroid gland was in the middle, and the lobes terminated above in a very 
 narrow point. 
 
 The opinion of the ancients, and which is also met with in Vesalius, that the human 
 subject has two thyroid glands, no doubt arose from the narrowness or absence of the 
 isthmus, or, rather, from the separation and complete independence of the two lobes in 
 a great number of animals. The surface of the thyroid body is smooth and well defined, 
 and sometimes divided into lobules by superficial furrows. 
 
 We shall examine in succession the relations of the middle and lateral portions : 
 
 The middle portion or isthmus is convex in froTit, and is separated from the skin by all 
 the muscles of the sub-hyoid region. Behind, where it is concave, it is in contact with 
 the first rings of the trachea. Moreover, this middle portion descends to a greater or 
 less distance in different subjects, and sometimes so low, that there is not room to per- 
 form tracheotomy between it and the sternum. 
 
 Each lateral lobe is convex in front, and corresponds with the muscles of the sub-hyoid 
 region : in particular, I ought to mention the sterno-thyroid, by which it is directly cov- 
 ered, and the breadth of which seems to be proportioned to the size of the lobe ; in many 
 cases of goitre I have seen this muscle twice or three times as broad as in the natural 
 state. 0)1 the inside, each lateral lobe is concave, so as to be applied to the side of the 
 trachea and cricoid cartilage, to the lower and latter part of the thyroid cartilage, to the 
 lower part of the pharynx, and to the upper part of the CESophagus. The two lobes, to- 
 gether with the middle portion or isthmus, form a half or sometimes three fourths of a 
 canal, which embraces all those parts ; an extremely important relation, which explains 
 how, in certain goitres, the trachea is flattened on the sides, deglutition is impeded, and 
 true asphyxia by strangulation is the final result. Behind, each lateral lobe corresponds 
 with the vertebral column, from which it is separated, on the outside, by the common 
 carotid artery, the internal jugular vein, and the pneumogastric and great sympathetic 
 nerves, which, according to the size of the gland, are either covered by it, or are merely 
 in relation with its outer surface. 
 
 The upper extremity of each lateral lobe terminates in a point, and hence the two- 
 homed figure assigned to the thyroid body. It is situated on the inside of the carotid 
 artery, in contact with the lateral and back part of the thyroid cartilage, and sometimes 
 extends nearly to its upper border. Its lower extremity is thick and rounded, descends 
 to a greater or less distance in different individuals, and corresponds to the fifth, sixth, 
 or seventh rings of the trachea : it is situated between the trachea and the common ca- 
 rotid. The inferior thyroid artery enters the gland at its lower extremity. 
 
 Its upper border is concave and notched in the middle ; the superior thyroid arteries 
 run along it. A prolongation extends from this border, which has been correctly repre- 
 sented by Bidloo, and named the pyramid by Lalouette. It almost always exists ; it 
 passes perpendicularly upward, either on the right or left side of the median line, and 
 presents numerous varieties in several respects. Thus it varies in its origin, sometimes 
 arising from the isthmus, and sometimes from one of the lobes at one side of the isth- 
 mus ; also in its termination, sometimes ending opposite the notch in the upper border 
 of the thyroid cartilage, sometimes opposite the thyro-hyoid membrane, and at other 
 times even on a level with the body of the os hyoides ; but always firmly adherent eithei 
 to the membrane or the bone. It also varies in its structure : sometimes it is a fibrous 
 cord, and sometimes a reddish linear band, which has all the appearances of a muscular 
 fasciculus, and has even been described as a muscle ; it often consists of a series of 
 gremules arranged in a line ; sometimes, again, we find, in the middle, or at one end of 
 the cord, a glanduliform enlargement, exactly resembling the tissue of the thjroid gland ; 
 lastly, it may be double, or bifurcated, or even completely wanting ; in which case, how- 
 ever, there exists a glanduliform mass of a certain height. This prolongation, in which 
 I and many others have in vain attempted to find an excretory duct, is evidently of a 
 compact nature. Is it the remains of a fcetal structure, or the trace of a normal dispo- 
 sition in some animals 1 
 
 The lower border of the thyroid body is convex, more or less deeply notched in the cen- 
 tre, and is in contact with the inferior thyroid arteries. 
 
 Structure. — The proper tissue of the thyroid gland is of a variable colour, sometimes 
 resembling the lees of Port wine, and sometimes of a yellowish hue. It is of tolerably 
 
THE UEINARY ORGANS. 435 
 
 nrm consistence, and feels granular. This organ presents all the anatomical characters of 
 glands, and, like them, may be separated by dissection into glandular grains ; but with 
 this difference, that these grains communicate with each other, while, in ordinary glands, 
 they are independent. The communication of the glandular grains may be shown in the 
 following manner : if the tube of a mercurial injecting apparatus be inserted into the 
 thyroid gland, the mercury will enter into and distend the cells, and after a certain time 
 all the grains will be injected ; it is easy to satisfy the mind that the mercury is not in- 
 filtrated into the cellular tissue, but is contained in the tissue of the gland itself, in the 
 centre of the granulations. The right and left lobes do not conununicate, but all the 
 granulations of each lobe communicate with each other. 
 
 The thyroid gland has, therefore, a vesicular structure ; and we have seen that the 
 glandular grains of all glands are spongy and porous, and that the products of their secre- 
 tion may be accumulated in these pores. 
 
 The glandular nature of the thyroid body is also shown by the viscid, Umpid, yellowish 
 fluid which pervades it in certain subjects, and which may be collected in sufficient 
 quantity for chemical analysis ; and also by the retention of this matter within a greater 
 or less number of the vesicles when their orifices of communication with the neighbour- 
 ing vesicles become obliterated. 
 
 But, in connexion with this view regarding its glandular nature, we seek in vain for an 
 excretory duct. If we examine the trachea and the larynx, or lay open the oesophagus, 
 and then press the thyroid gland, we shall see that no fluid escapes into those canals. 
 It has been asserted, indeed, that the excretory duct of the thyroid gland terminated in 
 the foramen ccecum of the tongue, in the ventricles of the larynx, or in the trachea opposite 
 its first ring ; but, after the example of Santorini, we are compelled to reject these fancied 
 and too hastily announced discoveries. 
 
 I may here notice the intimate adhesion of the side of the thyroid gland to the first ring 
 of the trachea. This can be very well shown by detaching the gland from behind for- 
 ward ; it is of a fibrous nature, and I have sometimes thought that I saw a duct in the 
 centre of it, passing through the membrane which connects the trachea with the cricoid 
 cartilage, though I have never been able satisfactorily to demonstrate it. 
 
 Still, I do not think that the absence of an excretory duct should remove the thyroid 
 from among the glandular organs ; for I believe that there exist in the body glands with- 
 out excretory ducts, as the thymus, the supra-renal capsules, and the thyroid body. The 
 secretion of the gland is entirely absorbed, and fulfils certain unknown uses. 
 
 Arteries. — The size and the number of the arteries distributed to the thyroid gland in- 
 dicate that something more than a mere nutritive process must be carried on in it. The 
 arteries are sometimes four, sometimes five in number ; two superior arise from the ex- 
 ternal carotid ; two inferior from the subclavian, and the fifth, or the thyroid artery of 
 Neubauer, where it exists, arises from the arch of the aorta. 
 
 The veiTis are proportionally as large as the arteries, and form so considerable a plexus 
 in front of the trachea, as, in certain cases, to have prevented the completion of the 
 operation of tracheotomy. 
 
 The lymphatic vessels terminate in the cervical lymphatic glands. 
 
 The nerves are derived from the pneumogastrics, and the cervical ganglia of the sym- 
 pathetic. 
 
 A thin cellular membrane envelops the gland, and sends very delicate prolongations 
 into its substance, where we find a very firm cellular tissue, always destitute of fat. 
 
 Development. — The thyroid gland is developed in two lateral halves, which are after- 
 ward united by a median portion. It is not uninteresting to remark, that this dispo- 
 sition, which is transitory in the foetus, represents the permanent condition of the gland 
 in a great number of animals. During intra-uterine life and infancy it is relatively larger 
 than at subsequent periods. Nevertheless, the changes which it afterward undergoes 
 are not to be compared with those that occur in the thymus ; and we cannot say, as of 
 the latter structure, that the existence of the thyroid body has any peculiar relations 
 with foetal life. 
 
 Functions. — It is a secreting organ, but the uses of its fluid are not known. 
 
 THE GENITO-URINARY ORGANS. 
 
 I HAVE thought it proper to describe the genital and the urinary organs together, because, 
 although their functions are very distinct, yet they have the most intimate anatomical, 
 physiological, and pathological connexions. 
 
 THE URINARY ORGANS. 
 Division. — The Kidneys and Ureters. — The Bladder. — The Supra-renal Capsules 
 The urinary organs form a very complex secretory apparatus, consisting of two secre- 
 ting organs, the kidneys ; of two provisional reservoirs, the calyces and the pelvis of each 
 kidney ; of two excretory ducts, the ureters ; of a second and final reservoir, the bladder ; 
 
436 SPLANCHNOLOGY. 
 
 and, lastly, of a second and final excretory canal, which, in the male, is common to both 
 the genital and the urinary organs, viz., the canal of the urethra. 
 
 The Kidneys. 
 
 The kidneys {ve^pol) are glandular organs, intended to secrete the urine. 
 
 They are deeply situated {k k,fig. 199) in the lumbar region, hence called the region of 
 the kidneys, on each side of the vertebral column, externally to the peritoneum, which 
 merely passes in front of them ; they are surrounded by a great quantity of fat, and, as 
 it were, suspended by the vessels which pass into and emerge from them. 
 
 Fixed firmly in this situation, they are but little liable to displacement. Most of the 
 changes in their position are congenital. The right kidney generally descends a little 
 lower than the left, doubtless on account of the presence of the liver. One of the kid- 
 neys may not uncommonly be found in front of the vertebral column, or even in the. 
 cavity of the pelvis ; and this unusual arrangement may, in certain cases, render diag- 
 nosis very obscure.* I have frequently found the right kidney in the corresponding iliac 
 fossa in females who had been in the habit of wearing very tight stays. This displace- 
 ment happens when the pressure of the stays upon the liver forces the kidney out of the 
 depression in which it is lodged in the lower surface of that organ. 
 
 Number. — The kidneys are two in number. It is not very uncommon to find only one, 
 which, is almost always formed by the union of the two, by means of a transverse portion 
 crossing in front of the vertebral column, and having its concave border directed upward. 
 
 Sometimes the two united kidneys are situated in the right or left lumbar region, or 
 ija the cavity of the true pelvis. Cases of union of the two kidneys should be distinguish- 
 ed from those in which one of them is atrophied. 
 
 Again, Blasius, Fallopius, Gavard, &c., relate examples of individuals having three 
 kidneys ; in some of these cases, two were situated upon the same side, in others the 
 supernumary kidney was placed in front of the vertebral column. 
 
 Size. — The kidney is not subject to such great variations in size as most other organs. 
 Its ordinary dimensions are from three and a half to four inches in length, two inches in 
 breadth, and one inch in thickness. Its weight is from two to four ounces, t I have 
 found them more than three times their ordinary size in a diabetic patient. When one 
 kidney is atrophied, the other becomes proportionally enlarged, sometimes even to twice 
 the usual dimensions. Atrophy of the kidney may be so extreme as to reduce it to a 
 drachm and a half or two drachms in weight, and make it appear to be lost among the 
 surrounding fat ; but the presence of this fat distinguishes such a case from one of con- 
 genital absence of the kidney.t 
 
 Density and Colour. — The tissue of the kidney is harder than that of other glands. 
 Its fragility accounts for its laceration by direct violence, or by a concussion produced 
 by a fall from a great height. 
 
 Its colour is that of the lees of red wine, somewhat analogous to that of the muscular 
 tissue, but offers several different shades. 
 
 Figure. — The shape of the kidney may be well compared to a bean, with the hilua 
 turned inward. This form enables us to consider its two surfaces and its circumference. 
 
 Relations. — The anterior surface of the kidney is directed slightly outward ; it is con- 
 vex,^ and is covered by the lumbar colon, but sometimes only by the peritoneum, the gut 
 lying to its inner side ; on the left side it is also in relation with the spleen and the great 
 tuberosity of the stomach, and on the right side with the liver and the second portion of 
 the duodenum. 
 
 The relations of the right kidney with the liver are more or less extensive ; sometimes 
 it is entirely covered by the liver ; in other instances it is inclined downward, and has 
 no relation with that organ. The gall-bladder sometimes lies upon the anterior surface 
 of the right kidney through the whole of its extent. Lastly, I have seen the kidney in 
 immediate relation with the parietes of the abdomen, through which it could be easily felt. 
 
 As practical inferences from these relations, we would notice the difficulty of explo- 
 ring the kidneys from the anterior surface of the abdomen, on account of their deep sit- 
 uation ; also, the possibility of an abscess of the kidney opening into the colon. 
 
 The posterior surface is less convex than the anterior, and is turned inward ; it corre- 
 sponds with the quadratus lumborum, from which it is separated by the anterior layer of 
 the fascia of the transversalis muscle ; with the diaphragm, which separates it from the 
 
 * 1 latplyhad in my warJs a female labouring under hectic fever, of which I could detect no cause, either in 
 the thorax or the abdomen. Upon opening the body after death, I found the two kidneys united, situated in 
 the true pelvis, behind the rectum, and projecting a little above the brim. They contained a large quantity of 
 pus, which escaped by the rectum. 
 
 + [According to M. Raver, the average weight of the kidney in the male is 4i ounces, in the female 3^ 
 ounces ; he also states that the left kidney is almost always larger and heavier than the right.] 
 
 t 1 do not speak here of enlargement of the kidneys from disease. Many examples of extreme enlargement 
 wall be found in my work on Pathological Anatomy, liv. i., xviii. 
 
 () Not unfrequently the fissure of the kidney is found on the anterior surface of this organ. In one case of 
 this kind, the right kidney occupied the right iliac fossa; it had two arteries, a superior, which proceeded di- 
 rectly to the fissure, and an inferior, arising from the angle of the bifurcation of the aorta, in front of the mid' 
 1 He sacral artery, and terminating at the lower extremity of the kidney. 
 
THE KIDNEYS. 
 
 437 
 
 (w6 or three lower ribs ; and with the psoas, which intervenes between it and the ver- 
 tebral column. These relations explain the possibility of exploring the kidney in the 
 lumbar region through the quadratus lumborum, account for abscesses of the kidney 
 opening in the lumbar region, and for the escape of renal calculi in the same direction, 
 and form the grounds on which the operation of nephrotomy has been proposed. It is 
 of importance to remark, that the relations of the kidneys with the ribs are variable in 
 extent, and that sometimes they do not pass beyond the last rib. 
 
 The circumference of the kidney presents an external border, convex, semi-elliptical, 
 and directed backward ; an internal border, directed forward, and deeply notched in the 
 middle, to form ih.e fissure of the kidney (hilus renalis, k,fig. 179). This notch is more 
 marked behind, where it corresponds with the pelvis of the kidney, than in front, where 
 it corresponds with the renal vein ; it is from fifteen to eighteen lines in depth. 
 
 If we separate the edges of this fissure, we expose a deep cavity containing fat, and 
 called the sinus ; in which are seen the pelvis of the kidney (p), the calices (c c c'), and 
 the divisions of the renal artery and vein. 
 
 The upper end of the kidney is directed inward, and is more or less completely em- 
 braced by the supra-renal capsule ; it is generally larger than the lower end, which is di- 
 rected slightly outward, and projects beyond the last rib. 
 
 Structure. — Make a vertical section of the kidney from its convex to its concave bor- 
 der. Detach the proper capsule in the same direction. Inject the arteries, veins, and 
 ureter, in different kidneys, and also in the same kidney. Inject also the uriniferous ducts. 
 
 The Proper Coat. — The kidney has no peritoneal covering. The remarkable fatty mass 
 in which it is imbedded is called the fatty capsule of the kidney. Besides this, it is pro- 
 vided with a proper fibrous coat, the external surface of which adheres to the fatty tis- 
 sue, by means of fibrous lamellae passing through it ; its internal surface is adherent to 
 the tissue of the kidney, through the medium of a number of small prolongations, which 
 are very easily lacerated. 
 
 The Tissue of the Kidney. — The kidney differs from other glands, all of which present 
 a homogeneous and granular texture, in being Fig. 179. 
 
 composed of two substances : one of these is ex- 
 ternal, cortical, or glandular {a a) ; the other inter- 
 nal, medullary, or tubular {b b b). Some anato- 
 mists have described a third substance, the mam- 
 millated ; but the papillas {d d) of which it is com- 
 posed belong to the tubular substance. 
 
 The following is the respective arrangement 
 of these two substances : 
 
 The cortical sabstance forms a soft, reddish, 
 sometimes yellow layer, of a granular appear- 
 ance, and about two lines in thickness, which 
 occupies the surface of the kidney, and sends 
 prolongations, in the form of pillars or septa, 
 from one to three lines thick, between the cones 
 of the tubular substance. 
 
 The tubular or medullary substance is redder, 
 and presents the appearance of striated cones or 
 pyramids (the pyramids of Malpighi), the bases 
 of which adhere to the cortical substance, while 
 their free apices are turned towards the sinus, 
 where they appear like papillae. Bellini, and, 
 before him, Berenger di Carpi, considered the 
 fibres or striae of the medullary substance as so many uriniferous tubes (the tubes of Bel- 
 lini), and hence the term tubular substance. 
 
 It follows, then, that the kidney is divided into a number of compartments, correspond- 
 ing to the number of cones of tubular substance ; there are from ten to twenty of these 
 compartments, which represent the temporary lobules of the human foetal kidney, and 
 the permanent lobules in the kidneys of the greater number of animals, t 
 
 The kidney, therefore, is formed by the union of a greater or less number of small kid- 
 neys, applied together, and connected within a common investment. We shall see, pres- 
 ently, that, in reference to the circulation, these small kidneys are entirely independent 
 of each other. Although the distinction between the two substances is well marked, it 
 is easy to see that some of the fibres or striae of the tubular structure penetrate the cor- 
 tical substance in a flexuous course, and reach the surface of the organ. This fact was 
 clearly shown by Ferrein, who considered the stri^ to be the excretory ducts of the gran- 
 ules. These cortical and flexuous portions of the tubes, which become straight as soon 
 as they reach the medullary substance, are termed the cortical ducts, or the convoluted 
 tubes of Ferrein. 
 
 * This figure is a plan, not an actual representation of the structure of the kidney. 
 + In some animals the kidney resembles a bunch of grapes. 
 
 SectioDafkidoey.* 
 
438 
 
 SPLANCHNOLOGY. 
 
 Ferrein having examined the tubes of Bellini under the microscope, believed that each 
 
 of them formed a pyramid analogous to those of the tubular substance, and that each of 
 
 these secondary pyramids consisted of about a hundred ducts ; hence the tubes of the 
 
 tubular substance have been named the pyramids of Ferrein,* in contradisl inction to the 
 
 pyramids of Malpighi. 
 
 We shall now examine the structure of the tubular and the cortical substance. 
 
 Structure of the Tubular Substance. — The tubular substance, which, at first sight, looKs 
 
 like muscular tissue, from its red colour and arrangement in lines, evidently consists of 
 
 tubes or ducts. 
 
 In fact, an examination under the simple microscope of a section made perpendicu- 
 
 Fig. 180. larly to the axis of the tubes, demonstrates the existence 
 
 6 \ of a number of small openings, each corresponding to a 
 
 tube ; and if, while the eye is fixed upon the section, the 
 
 kidney be compressed, urine will be seen to exude from all 
 
 points of the cut surface. Direct injection of the ducts, by 
 
 means of a tube containing mercury, introduced at hazard 
 
 into the tubular substance, will fill all the tubes, in whatever 
 
 direction the instrument may be directed. The ingenious 
 
 experiment performed by Galvani, who tied the ureters of 
 
 birds, and by this means obtained an injection of the tubes 
 
 with the white matter of their urine, leaves no doubt of the 
 
 existence of these tubes. Lastly, the tubes themselves are 
 
 collected together in the papillae, and open either over their 
 
 entire surface, or in a small depression which sometimes 
 
 exists at their summits. 
 
 Structure of the Cortical Substance. — The cortical sub- 
 stance is tubular and granular. The granules are regularly 
 disposed around the convoluted tubes of Ferrein. t 
 
 On examining a thin slice of uninjected kidney by the 
 simple microscope, we perceive a great number of oval and 
 spheroidal granules {c",fig. 180), the acini of Malpighi, which 
 may be separated from each other by maceration ; and 
 those granules which have been cut through present that 
 spongy appearance, resembling the pith of the rush, which 
 seems to belong to all glands. When the section is verti- 
 cal, these corpuscles are seen appended to the tubes of 
 Ferrein, like grapes upon their stalk. <J 
 
 Vessels and Nerves. — The renal artery is remarkable for 
 its enormous size, in proportion to that of the kidney, for its origin from the aorta being 
 at a right angle, and for its shortness. There are sometimes two or three renal arteries, 
 and two are not unfrequently found twisted spirally around each other. 
 
 When the kidney is situated in the iliac fossa or in the pelvis, the renal artery or ar- 
 teries generally arise from the common iliac. 
 
 The re7ial vein is as large in proportion as the artery, and passes in front of it into the 
 vena cava. 
 The lymphatic vessels are but little known. 
 
 The nerves are very numerous, and are derived from the solar plexus ; besides which, 
 the lesser splanchnic nerve is distributed directly to the kidney. 
 
 The spermatic nervous plexus is formed by branches from the renal plexus, and this 
 may explain the close sympathy between the testicle and the kidney. The great num- 
 ber of ganglionic nerves distributed to the kidney may account for the peculiar charac- 
 ter of the pain experienced in this organ. 
 
 Injection of the Renal Vessels. — A very coarse injection thrown into the artery will re- 
 turn by the veins. One thrown into the vein will return by the ureter, and not by the 
 
 * See note, infra. 
 
 t According to Ferrein, these convoluted tubes form, by their numerous anastomoses, a network, in the 
 meshes of which the granules arc contained. 
 
 t This is a plan, rather than an actual representation. 
 
 t> [The urinifcrous tubes, commencing at their orifices upon the surface of the papillae, pass up into the tu- 
 bular portion of the kidney, dividing and subdividing dichotomously several times {a, fig. 180), so as to consti- 
 tute fasciculi of straight and radiating tubes : these are the pyramids of Ferrein, a considerable number of 
 which are united to form one of the pyramids of Malpighi (b,fig. 179). At the base of the latter the fasciculi 
 spread out, and the straight tubes become the convoluted tubes of the cortical substance (fig. 180). 
 
 In the human kidney, the tubuli uriniferi are said by Weber to be of a nearly uniform diameter throughout 
 their entire course (averaging ^^ th of an inch) ; and all appeared to him to end in loops (b b), none in free 
 and closed extremities (as at b') : according to Krause, they terminate in both ways. In either case, however, 
 they form a closed system of tubes, independent of the bloodvessels, which merely ramify on their parietes. 
 They are lined with a mucous membrane, continuous with that on the papillae, and having a columnar epi- 
 thelium. 
 
 The acini of Malpighi, or granules of M. Cruveilhier (c"), are not of a glandular nature ; they consist en- 
 tirely of minute convoluted arteries, which terminate in the veins, but have no direct communication, as wai 
 formerly supposed, with the uriniferous tubes ; they are called the glomeruli.'] 
 
 Ma^ified sixty timu.t 
 
THE KIDNEYS. .^^ 
 
 artery.* Having filled the artery with red injection, the vein with blue, and the ureter 
 with yellow, I observed the following facts : 
 
 The renal artery divides into several branches within the sinus, where it is surround- 
 ed with fat ; these branches pass between the calyces, and then between the cones of 
 the tubular substance, proceeding as far as the conunencement of the cortical substance 
 without giving off any smaller branches : at that point, however, they divide and subdi- 
 vide, so as to form a vascular network, the meshes of which are quadrilateral and of 
 different sizes, inscribed within each other. The largest of these meshes embrace the 
 entire base of each pyramid ; the smaller pass in different directions through the sub- 
 stance of the bases. 
 
 In order to obtain a good view of this arrangement, it is necessary to divide an inject- 
 ed kidney along its convex border, and scrape away the tubular substance, which is so 
 soft as to be easily removed. We shall then perceive that the arterial and venous net- 
 work, corresponding to the base of each cone, is surrounded by a very thick fibrous sheath, 
 apparently prolonged from the fibrous coat, which passes into the hilus. All the tubular 
 substance being thus removed, the remaining cortical portion of the kidney presents the 
 appearance of a series of perfectly distinct alveoli, each of which corresponds to a cone 
 of the tubular substance. A very beautiful preparation may thus be made. 
 
 It remains for us to inquire how the arteries terminate. A number of vessels pro- 
 ceed from the convexity of the vascular network above described, traverse the cortical 
 substance, become twisted like tendrils of the vine, and appear to terminate in small red 
 masses, regularly arranged along the convoluted tubes of Ferrein. These small red 
 masses are formed by the penetration of the injection into the cavity of each granule, as 
 may be seen by examining a section of the kidney with a lens.f If both the artery and 
 the vein be injected in the same kidney (and it is of importance that the vein should be 
 injected before the artery, in order to prevent a mixture of the two injections), we shall 
 see that the matter injected by the vein circumscribes that injected by the artery. 
 
 Almost all the vessels are destined for the cortical substance, the tubular substance 
 scarcely receiving any branches :$ the vessels of any one lobule do not communicate 
 with those of the adjacent lobules. 
 
 Injection thrown into the ureter does not enter the uriniferous ducts, or, at leeist, very 
 incompletely. 
 
 Development. — The surface of the kidney in the foetus, as in the lower animals, is fur- 
 rowed and lobulated. Each lobule is fonned by the medullary substance, covered by a 
 layer of the cortical substance. After birth the furrows are effaced, and the surface of 
 the kidney becomes plane and smooth. 
 
 This change takes place during the first three years after birth ; nevertheless, the lo- 
 bular arrangement not unfrequently continues for nine or ten years, and even during the 
 whole periwi of life. When the kidney is the seat of disease, and more particularly 
 when it is distended from an accumulation of urine within the calyces and pelvis, the lob- 
 ular arrangement reappears. Each lobule is then converted into a pouch, which is 
 perfectly distinct from those in contact with it. The kidney is proportionally larger in the 
 foetus than in the adult. 
 
 Functicms. — The kidneys are the secreting organs of the urine. The urine is secreted 
 by the cortical substance, and, as it were, filtered by the tubular substance ; for perfect- 
 ly-formed urine is found in the former situation. The mechanism of this is not better 
 known than that of other secretions ; its rapidity is explained by the great quantity of 
 blood received by the kidneys. 
 
 The Calyces, Pelvis, and Ureter. 
 
 Dissection. — Remove the fat from the sinus, and study the arrangement of the pelvis 
 and calyces externally. Divide the kidney from the convex border towards the hilus. 
 
 The calyces (c c c', fig. 179) are funnels (infundibula), or, rather, small membranous 
 cylinders, embracing the bases of the papillae by one of their extremities, almost in the 
 same manner as the corolla of a flower embraces the stamina and pistil, and uniting at 
 their other extremity with the adjacent calyces, to form the pelvis of the kidney. They 
 vary in number like the papillae, or even more so, for two or three papillae frequently 
 open into the same calyx. Whatever their number may be, they generally unite into 
 three trunks, a superior, a middle, and an inferior, which correspond to the three groups 
 of lobules, into which the kidney may be divided. These three trunks unite to form the 
 pelvis. The external surface of the calyces is in relation with a great quantity of fat, 
 and with the divisions of the renal artery and vein. 
 
 The pelvis (p) is a small membranous pouch, situated behind the renal artery and vein, 
 opposite the deep notch in the posterior border of the hilus, so that, when seen from be- 
 hind, it projects completely beyond that fissure. It is elongated from above downward, 
 
 * [This is the result of rupture.] t See note, suprd. 
 
 t [The vessels (c,fig. 180) of the tubular portion nm parallel with the tubuli from the cortical substance 
 to the papillae ; they were mistaken by Ruysch fur the tubub themselves, which were, therefore, supposed by 
 him to communicate with the arteries in the glomeruli.] 
 
440 SPLANCHNOLOGY. 
 
 and flattened from before backward, and may become greatly dilated from retention of 
 the urine, or from renal calculi : almost immediately after its commencement it becomes 
 smaller, and takes the name of the ureter. In certain cases it would appear that there is 
 no pelvis, and that the ureter succeeds immediately to the two or three trunks formed 
 by the union of the calyces. The pelvis is, therefore, nothing more than the expanded 
 or infundibuliform commencement of the ureter. 
 
 The ureter {ovpov, urine, u, Jigs. 179, 181, 199) is the excretory duct of the kidney, 
 and ex ends obliquely from the pelvis of that organ to the inferior fundus {bos fond) of 
 the bladder. It is generally single on each side, but sometimes double, and that under 
 two very different circumstances : for example, where the two kidneys are united into 
 one, a double ureter is almost invariably found ; and, secondly, when, there being two 
 kidneys, one of them is divided into two very distinct portions. In the latter case the 
 two ureters are often united into one, after a course of a few inches. There is, then, no 
 pelvis properly so called, and the two ureters may be regarded as the prolongation of the 
 two trunks of the calyces, which remain separate longer than usual. 
 
 The ureter is a cylindrical tube, having whitish, thin, and extensible parietes, and va- 
 rying in size from that of a crow's to that of a goose's quill. The most contracted por- 
 tion of the canal is that situated in the substance of the parietes of the bladder. Occa- 
 sionally it presents, at various parts of its extent, some circumscribed dilatations, which 
 seem to indicate that the course of the urine had been for a time arrested. Tiiis canal 
 is liable to extreme dilatation, when any obstacle occurs to the passage of the urine : I 
 have seen it as large as the small intestine. 
 
 Each ureter is directed obliquely downward and inward, as far as the side of the base 
 of the sacrum : from this point {fig. 181) it passes downward, forward, and then inward 
 (Uffig. 186), to the lateral part of the inferior fundus (a) of the bladder, where it enters 
 between the muscular and mucous coats, and passes obliquely for about ten lines within 
 the substance of that organ, to one of the posterior angles of the trigone, at which point 
 it opens by an orifice narrower than the canal itself, and having the form of a parabolic 
 curve, with its concavity directed inward. 
 
 Relations. — In proceeding from the pelvis of the kidney to the base of the sacrum, the 
 ureter passes edong the anterior margin of the psoas, and is covered by the peritoneum 
 and by the spermatic vessels, which cross it very obliquely. The right ureter is in rela- 
 tion with the vena cava inferior, being situated on its outer side. Opposite the base of 
 the sacrum, each ureter crosses the common iliac, and then the external iliac artery and 
 vein of its own side. In the pelvis, the ureter is applied to the parietes of that cavity, 
 is covered by the peritoneum, and crosses in succession the umbilical artery, or the cord 
 by which it is replaced, the obturator vessels, the vas deferens (,t,fig. 181) in the male,* 
 and the upper and lateral part of the vagina in the female. That portion of it which is 
 contained within the substance of the walls of the bladder corresponds indirectly with 
 the neck of the uterus ; and this important relation explains why carcinoma of the neck 
 of the womb is so frequently accompanied with retention of urine. I have also observ- 
 ed that the ureters of all females who have died after delivery, or during the last months 
 of pregnancy, are remarkably dilated. 
 
 Internal Surface. — The internal surface of the calyces, pelvis, and ureters is white, 
 smooth, and has longitudinal folds, which are effaced by distension. There are no 
 valves, either at the opening of the calyces into the pelvis, or of the pelvis into the ure- 
 ter, or in any part of that canal. 
 
 Structure. — ^The calyces, the pelvis, and the ureter have all the same structure : they 
 are formed by two membranes ; an internal membrane, continuous with the vesical mu- 
 cous membrane, very thin, and even having the appearance of a serous membrane ; it is 
 reflected from the calyces upon the papillas, and is prolonged into the uriniferous tubes : 
 an external membrane, which is very thick, and supposed to be a continuation of the ex- 
 ternal coat of the kidney, and therefore to be fibrous. Others regard it as muscular ;t I 
 believe that it is formed of a tissue analogous to the dartos. Some arteries and veins, 
 probably, also, some lymphatics and nerves, are distributed upon the calyces, the pelvis, 
 and the ureters, but do not require any special description. 
 
 The Bladder. 
 
 The Madder {h,Jig. 181) is a musculo-membranous sack, which serves as a reservoir 
 for the urine. 
 
 It is situated in the cavity of the pelvis, upon the median line, behind the pubes (6), 
 and is retained in that position by the peritoneum (m), which only partially covers it, 
 and by the urachus, a sort of ligament connecting it with the umbilicus. These means 
 of attachment are in accordance with the great enlargement of which the organ is ca- 
 pable ; but they cannot prevent certain partial displacements, known as hcrnice of the 
 llcdde'' When collapsed, it is completely protected from external injury ; but when 
 
 * Passing to its outer side. 
 
 ^ [lu some quadrupeds the ureter distinctly contracts on applying a stimulus.! 
 
THE BLADDER. 
 
 441 
 
 filled, it passes above the osseous girdle in which it is contained, and enters the dilatable 
 cavity of the abdomen, where it can be distended to the utmost without inconvenience. 
 
 Number. — The bladder Fig. 181. 
 
 is always single ; the ex- 
 amples of double bladder 
 which have been recorded 
 are cases of protrusion of 
 the mucous membrane 
 through the separated 
 muscular fibres. But, 
 whatever may be the size 
 of these accidental blad- 
 ders (and I have seen 
 them twdce as large as the 
 true bladder to which they 
 were attached), they may 
 always be distinguished 
 by their having no muscu- 
 lar coat. The cases of de- 
 ficiency of the bladder are 
 generally examples of that 
 species of malformation, 
 in which the viscus is open 
 anteriorly, and is everted, 
 80 as to resemble a fungous mass. 
 
 Dimensions. — The bladder is the largest of all the reservoirs of secretion ; but its ca- 
 pacity varies, from a number of circumstances : from hahit — in persons who are accus- 
 tomed to retain their urine for a considerable period, the bladder is more capacious than 
 in those who immediately attend to the desire to pass urine ; from sex — thus, in the fe- 
 male the bladder is generally larger than in the male, because she is more influenced by 
 the customs of society ; from age — ^the bladder appears to be relatively larger before 
 than after birth ; from disease — in consequence of which it presents every variety be 
 tween a morbid state of contraction, in which, from the contact of its parietes, it scarce 
 ly permits the accumulation of a spoonful of urine, and an extreme state of dilatation, in 
 which it can hold several pints of that fluid. 
 
 Direction. — The direction of the bladder is determined by that of the anterior wall of 
 the pelvis, so that its axis is oblique from above downward and backward. On account 
 of this obliquity, a slight inclination of the trunk forward makes the neck of the bladder 
 the most dependent part of the organ. The obliquity becomes still greater when the 
 distended bladder has escaped from the pelvis and entered the cavity of the abdomen : 
 its axis then exactly corresponds with that of the brim of the pelvis, i. c, it is directed 
 from the umbilicus to the lower part of the curvature of the sacrum. It has been said, 
 since the time of Celsus, that the upper part of the bladder is a little inclined to the left 
 side, but I have not observed this. 
 
 Shape. — The bladder is ovoid, the great end being directed downward and the smaller 
 upward. Its shape differs according to age and sex, and in different individuals. The 
 sexual differences are not congenital ; they seem to result from the pressure to which 
 the female bladder is subjected during pregnancy ; but the transverse enlargement and 
 the vertical shortening of the bladder in a female who has borne children are not so 
 well marked as is generally said. 
 
 Relations. — In determining these, the bladder is divided into the fundus, which is the 
 highest and the narrowest part ; the body, or middle portion ; and the base, which is the 
 lowest and the broadest portion. It has, moreover, like all hollow organs, an external 
 and an internal surface. 
 
 The external surface of the bladder is convex, and presents six regions for our con- 
 sideration, the relations of which we shall now study, both in the collapsed and distend- 
 ed condition of the viscus. The anterior region, not covered by the peritoneum, is in 
 relation with the symphysis and bodies of the ossa pubis, and with the internal obtura- 
 tor muscles, with which parts it is connected by a very loose serous cellular tissue, in 
 stout persons more or less loaded with fat. Some fibrous bundles pass from the lower 
 part of this region, and are attached to the sides of the symphysis ; they are called the 
 anterior ligaments of the bladder, and are traversed by numerous veins ; they are a de- 
 pendance of the superior pelvic aponeurosis (q,fig. 181). (Vide Aponeurologv.) In 
 the female, on account of the absence of the prostate, the anterior region of the bladder 
 passes below the symphysis, and advantage may be taken of this circumstance in the 
 extraction of calculi. When the bladder is full, its anterior region corresponds imme- 
 diately with the parietes of the abdomen, and sometimes rises as high as the umbilicus. 
 The practical conclusions to be derived from these relations refer to the examination 
 of the bladder in the hypogastrium, to puncture of this organ in the same situation, to 
 
 Kkk 
 
i 
 
 442 SPLANCHNOLdGT. 
 
 the high operation for stone, to the operation of dividing the symphysis, and, lastly, to 
 ruptures of the bladder in consequence of fracture of the pubes.* 
 
 The posterior region of the bladder is covered by the peritoneum (u) throughout the 
 whole of its extent ; in the male it corresponds with the rectum (o), and in the female 
 with the uterus. Some convolutions of the small intestine almost always intervene be- 
 tween the bladder and those parts. 
 
 The lateral regimis are also covered by the peritoneum ; and passing upon each of 
 them are found the umbilical artery in the foetus, and subsequently the hgament by which 
 it is replaced, and also the vas deferens (0 in the male. When the bladder is perfectly 
 contracted, there is some distance between it and that vessel and duct on either side. 
 
 The relations of the hwer region or base of the bladder, which are all very important, 
 differ in the two sexes. 
 
 In the male it corresponds to the rectum, from which it is separated on either side in 
 front by the vesicula seminalis («) and the vas deferens {t). The only part in direct re- 
 lation with the rectum is, therefore, the triangular space {fig. 186) comprised between 
 the vesiculae (s s') and the vaisa deferentia (J, I') of the two sides. It is of importance to 
 remark, that the peritoneum, where it is reflected from the rectum upon the posterior 
 region of the bladder, forms a more or less deep cul-de-sac in the middle, and two small 
 folds on the sides, which have been improperly named the posterior ligaments of the blad- 
 der. When the bladder is much contracted, the peritoneum covers the whole of the 
 space between the vesiculae and the vasa deferentia ; so that, properly speaking, there 
 is no immediate relation between that organ and the rectum. On the other hand, when 
 it is distended, it becomes much enlarged posteriorly, and has much more extensive re- 
 lations with the rectum, t It is important, also, to remark, that the peritoneum is very 
 loosely united to the base of the bladder, so that they can be easily separated whenever 
 it is desirable to reach the bladder from the rectum. On each side of the rectum the 
 base of the bladder corresponds with the cellular tissue of the pelvis. The superior pel- 
 vic fascia and the levatores ani are attached to and embrace the sides of the base. 
 
 In the female, the base of the bladder corresponds not only with the vagina, but with 
 the lower half of the neck of the uterus ; it adheres very intimately to the former, but 
 loosely to the latter. 
 
 As practical consequences of these relations, I would point out the following : In the 
 male, the occurrence of recto-vesical fistulae, the possibility of exploring the bladder by 
 the rectum, and of operating upon it in the same situation. In the female, the capability 
 of examining the bladder by the vagina, of puncturing it, and of performing lithotomy 
 through the same part ; the occurrence of vesico- vaginal fistulae, and the frequency with 
 which carcinoma of the bladder follows the same affection of the cervix uteri. 
 
 Summit, or Fundus. — This part of the bladder is directed forward and upward, and is 
 covered by peritoneum. The urachus is a sort of cord, having a muscular appearance, 
 and stretching from the summit of the bladder to the umbilicus, into which it appears to 
 enter. This cord adheres tolerably firmly to the peritoneum,^ which forms a falciform 
 fold over it, and may be drawn down with it when it is displaced. In a case of hyper- 
 trophy of the bladder, I found the cord it^lf hypertrophied, and continuous with the longi- 
 tudinal muscular fibres of the bladder, almost in the same way as the round ligament of the 
 uterus with the fibres of that organ. The urachus is merely the vestige of a canal which ex- 
 ists in the foetus of quadrupeds, and, according to several authors, in the human foetus also. 
 
 There have been many discussions upon this subject, some stating that the cord is 
 hollow, others that it is solid. I have always found it solid, both in the adult and in the 
 foetus. In one case I found a small concretion in it, which I regret not having submit- 
 ted to chemical analysis. It is very common to find the urachus large at its origin, and 
 becoming narrower after a course of two or three inches, and then blending with the 
 cord, which takes the place of the left umbilical artery ; at other times it expands into 
 cellular tissue, and the filaments resulting from its division proceed, some to the umbili- 
 cus, and others to the cords which represent the obliterated umbihcal arteries. 
 
 In the erect posture, the weight of the intestines presses on the summit of the bladder, 
 which is thus pushed downward ; and hence the necessity for placing the patient, during 
 certain operations, especially that of lithotrity, in the horizontal position, or even on an 
 inclined plane, so arranged that the pelvis is more elevated than the shoulders. 
 
 The internal surface of the bladder is covered by a mucous membrane, hke all cavities 
 which conununicate with the exterior ; and is remarkable for certain folds or wrinkles, 
 which are effaced by distension, and for the reticular ridges formed by the fasciculi of 
 its muscular coat ; these are sometimes very highly developed, and, in certain cases, 
 
 * It has even been proposed to puncture the bladder through the symphysis, by means of a flattened tro- 
 car ; but the difficulty of coming exactly upon the symphysis will probably prereut the execution of this plan. 
 
 t The varieties in the depth of the cul-de-sac formed by the reflected peritoneum, pointed out by modern 
 •nrgeons, appear to me to be explicable by the difference in size of the bladders examined. The arrange- 
 ment of the peritoneum seems to me to be exactly the same in all subjects. 
 
 t It would appear, from a fact which I have observed, that the bladder cannot be dragged into either inter- 
 nal abdominal rin^, excepting after the urachus ; this being itself drawn down by the peritoneum, with whick 
 it is closely united. 
 
THE BLADDER. 
 
 443 
 
 are so large, that they form pillars, which project into the interior of the bladder. The 
 mucous membrane not unfrequently becomes insinuated between these columns, so as 
 to form cells, or what is termed sacculated bladder. The base of the bladder presents 
 three openings, viz., the orifices of the two ureters (r r,fig. 182), and the opening into 
 the urethra. These three openings occupy the angles of an equilateral triangle (" coUi- 
 cula ab ureteribus ad urethram producta," Holler), the sur- pig. 182. 
 
 face of which is smooth and white, and is always devoid of 
 wrinkles or columns. This is the trigone of the bladder, or 
 trigone of Lieutaud, which has been supposed to possess a 
 pecuhar degree of sensibihty. The posterior border (r r) of 
 this trigone is more or less prominent in different individ- 
 uals, and is formed by a line stretching between the orifices 
 of the two ureters ; this prominence is prolonged outward 
 on each side by the portion of the ureter which lies in tl>e 
 parietes of the bladder. It has been stated incorrectly, that 
 the trigone is formed by the projection of the prostate, for it 
 exists in females as well as in males, though it is less prom- 
 inent than in the former. All that part of the base of the 
 bladder which is behind the trigone is generally called the 
 las fond, ot inferior fundus.* 
 
 Most anatomists follow Lieutaud in describing, under the 
 name of uvula vesica, a tubercle which arises from the low- 
 er part of the orifice of the urethra, and partially fills up that 
 opening ; but it exists only in cases of disease, being the re- 
 sult of hypertrophy of the middle portion of the prostate, de- 
 scribed by Home as the middle lobe. 
 
 The orifices of the ureters are so constructed as to per- 
 mit the easy passage of the urine into the bladder, but com- 
 pletely to oppose its reflux. Their long oblique course be- 
 neath the mucous membrane before opening into the blad- 
 der explains this arrangement. The raised and reflected 
 portion of the membrane might be called the valve of the ureter. 
 
 The opening of the urethra, which is also called the neck of 
 the bladder, is habitually closed, and, as it were, corrugated. 
 Some force is required in order to overcome the resistance 
 offered by it ; the crescentic form which has been attributed to it is not very evident. 
 
 Structure. — The bladder has three coats : a peritoneal, which is incomplete, a muscu- 
 lar, and a mucous coat ; these are connected by layers of cellular tissue : it has also ves- 
 sels and nerves. 
 
 The peritoneal coat covers the posterior and laterjil regions, and the inferior fundus of 
 the bladder. The anterior region, and that part of the base which is in front of the infe- 
 rior fundus, are not covered by it. It is united to the muscular coat by very loose cellu- 
 lar tissue. 
 
 The muscular coat is formed of interlacing fibres, the direction of which it is, at first 
 sight, very diiScult to determine. + This coat is very thin, and does not form a continu- 
 ous layer in enlarged bladders ; but in small and contracted bladders it is continuous, 
 and consists of several layers, and may even acquire a thickness of eight or ten lines 
 from hypertrophy. It is, then, very easy to determine the direction of the fleshy fibres, 
 which seem to form a number of layers. The external layer consists of longitudinal 
 fibres, all of which proceed from the neck of the bladder, and expand over the whole sur- 
 face of the organ ; the next layer is formed of circular fibres, some of which are irregu- 
 larly interlaced, while the others are parallel. The regular circular fibres are most nu- 
 merous opposite the inferior fundus of the bladder, and are continuous with the annular 
 fibres of the neck. 
 
 The irregular circular fibres are most common in the posterior region of the organ. In 
 the situation of the trigone, the muscular layer consists of transverse parallel fibres, pla- 
 ced near each other, and forming a perfectly regular plane. The transverse thick bun- 
 dle stretching between the orifices of the ureters has been regarded by Sir C. Bell as the 
 muscle of the ureters. Its contraction, by enlarging their orifices, will facilitate the 
 entrance of the urine into the bladder. 
 
 The term sphincter of the bladder is applied to a muscular ring, which is continuous 
 with the circular fibres of the body of the bladder, and is situated at the opening of the 
 urethra. The vagueness and disagreement in the descriptions of this sphincter suffi- 
 ciently prove that no very distinct structure of the kind exists at the neck of the blad- 
 der. Winslow describes some fibres arising from the ossa pubis, and embracing tie 
 
 * It is not uncommon to find the bladder forming behind the trigone a deep cul-de-sac, which I have seen 
 insinuated between that part and the rectum. _ 
 
 t [These fibres belong to the involuntary class, the microscopic characters of which are described in the 
 note, p. 32.-?.] 
 
444 SPLANCHNOLOGY. 
 
 sides of the vesical orifice, as the sphincter muscle, but they evidently belong to the le- 
 vator ani. It is certain, however, that, in the neck of the bladder, there is a thin exter- 
 nal layer of longitudinal muscular fibres, and also a deep and very thick layer formed of 
 circular fibres ; both layers seem to be continued into the prostatic portion of the urethra 
 
 The mucous coat is extremely thin,* of a whitish colour, and presents some small papil 
 lae. It is so difficult to demonstrate its follicles, that their existence has been denied ; 
 but, with a little attention, they may always be found in the neighbourhood of the neck 
 of the bladder, and upon the trigone. I have seen them in all parts of the bladder, under 
 the form of vesicles, in certain cases of disease. The mucous membrane is moulded 
 upon all the ridges of the muscular coat : it sometimes dips between the muscular bun- 
 dles, and forms cells, in which calculi are often lodged. Bladders of this kind are call- 
 ed sacculated, and, moreover, are almost ,a\vf?iys fasciculated ; i. e., the muscular fibres 
 are so highly developed as to raise up the mucous membrane into ridges. The cellular 
 tissue uniting the muscular and the mucous coats is tolerably loose, serous, and extreme- 
 ly delicate. 
 
 Vessels and Nerves. — The vesical arteries arise either directly from the hypogastrics, or 
 from their branches. They are variable in number. The veins form a very remarkable 
 plexus around the neck of the bladder, which is prolonged upon the sides of the inferior 
 fundus, and terminates in the hypogastric veins. The lymphatic vessels are, for the most 
 part, situated between the muscular and the peritoneal coats, and terminate in the hypo- 
 gastric lymphatic glands. The nerves are derived from the hypogastric plexus, which is 
 composed both of ganglionic and spinal nerves ; and hence the bladder is partly subject 
 to, and partly beyond the influence of the will. 
 
 Development. — The bladder of the foetus is remarkable for the predominance of its ver- 
 tical over its transverse diameters, the latter being very short. This fact, added to the 
 imperfect development of the pelvis, explains why the entire bladder projects above the 
 brim of the pelvis at this period of life. The inferior fundus does not exist. The sum- 
 mit is gradually continued into the urachus, which is then much larger than at subse- 
 quent periods, and of which the bladder appears to be merely an expansion. According 
 to some authors, the bladder is relatively larger, and, according to others, smaller before 
 than after birth. 
 
 In the early periods of infancy, the bladder retains tht characters which it had in the 
 foetus, and many important surgical inferences may, therefore, be drawn from its more 
 extensive relations with the abdominal parietes. In proportion as the pelvis is devel- 
 oped, and also, perhaps, in proportion as the frequently-accumulated urine dilates the 
 bladder in its transverse and antero-posterior diameters, this organ sinks into the pelvic 
 cavity, and, when completely developed, presents the characters already assigned to it. 
 
 The urachus, which, we have seen, is converted into a muscular cord in the adult, and 
 is sometimes lost before reaching the umbilicus, is much more developed in the foetus : it 
 may then be traced as far as the umbilicus, and even, according to some anatomists, 
 through the whole extent of the umbilical cord. Analogy, and some observations upon 
 the human subject, would seem to show that the urachus is hollow in the foetus. In the 
 lower animals the cavity of the urachus may be traced into a bag called the allantois, 
 which is situated between the membranes of the ovum ; and it is stated by several au- 
 thors, that they have caused mercury injected into the bladder to pass some distance 
 (half an inch, one inch, or one inch and a half) into the urachus, and even for a greater 
 or less extent into the umbilical cord. 
 
 Moreover, in new-born infants, and even in adults, the urine has been seen to escape 
 through the umbilicus ; but, in these cases, the urethra is always obliterated. I have 
 already said that I have met with a calculous concretion within the substance of the 
 urachus, and I find that Haller and Harder have made a similar observation {arenuliB in 
 uracho visa,). M. Boyer {Traiti d" Anatomic, p. 477, Splanchnoi ogie) says that he has 
 dissected the bladder of a man twenty-six years of age, whose urachus formed a canal 
 an inch and a half long, and contained twelve urinary calculi as large as millet-seeds ; 
 one of them was larger, and resembled a grain of barley. He convinced himself that the 
 canal which contained these calculi was not formed by a prolongation of the internal 
 membrane of the bladder through the other coats. On the other hand, a number of ob- 
 servers (myself among them) have found the urachus solid in the foetus. New facts are, 
 therefore, necessary to settle this anatomical question ; although it is very probable that 
 the urachus of the human subject is of the same nature as that of animals, but becomes 
 obliterated at a much earlier period. 
 
 Functions. — The bladder is intended as a reservoir for the urine, and is also the prin- 
 cipal agent in its expulsion. The urine constantly trickles, drop by drop, into the blad- 
 der, but cannot flow back by the ureters, on account of the mechanism already described. 
 Wlien the bladder is distended, it occasions a desire to evacuate its contents, and the 
 urine is then expelled by the combined action of the bladder itself and the abdominal 
 muscles. I have said that the bladder is the chief agent in this expulsion, for, in cases 
 
 * [This and all the other portions of the genito-urinary mucous membrane have <in epithelium, which ap- 
 •roaches to the columnar in character.] 
 
THE SUPRA-RENAL CAPSULES. 445 
 
 of retention of urine from paralysis, or excessive distension of the bladder, the most 
 powerful contractions of the abdominal muscles are not sufficient to expel it. 
 The Supra-renal Capsules. 
 
 The supra-rend capsules (c c,Jig^. 199) are organs whose use is unknown ; they are situ- 
 ated near the upper end of the kidneys, and, hke them, are outside of the peritoneum. 
 
 The proximity of the kidneys and supra-renal capsules has led to the supposition that 
 there is some mutual relation between their functions ; and hence they are generally de- 
 scribed together, though not on perfectly just grounds.* The name renes succenturiati 
 ( Casserius) is sufficient evidence of the relation which has been supposed to exist be- 
 tween these organs. Nevertheless, this connexion of situation, which constitutes the 
 most important and characteristic feature in the history of the supra-renal capsules, is 
 not constant ; and, in the numerous cases in which the kidneys occupy some unusual 
 position, the supra-renal capsules do not accompany those organs in their displacement. 
 Thus, when the kidneys are situated higher than usual, the capsules are placed on their 
 inner side, and correspond vsith the renal fissure ; when the kidneys occupy the pelvic 
 region, the capsules undergo not the slightest change in their position, and no longer 
 have any connexion with them. 
 
 Number. — There are two supra-renal capsules ; it is said that two have been found on 
 each side. 
 
 Size. — They vary much in size in different individuals : sometimes they are so small 
 that they can scarcely be distinguished from the fat by which the kidney is surrounded ; 
 at other times they are very large. In a case where the two kidneys were very small, 
 I found the supra-renal capsules much larger than usual. It has been said that they are 
 larger in the negro than in the Caucasian race. I have examined two negroes, and did 
 not find them unusually large. In the foetus they are proportionally larger than in the 
 adult. I have found them very large in several females far advanced in years. 
 
 The two capsules are not of the same size. Eustachius affirms that the right is 
 larger than the left ; but I have generally found the reverse. Their weight is about one 
 drachm. 
 
 Form. — I shall follow the example of M . Boyer, in comparing these supra-renal capsules 
 to a helmet, flattened on its anterior and posterior surfaces, and embracing the upper 
 end of the kidney by a narrow and concave surface. The relations of its anterior surface 
 are different on the right and the left side. 
 
 On the right side it is in relation with the liver, to which it adheres by a tolerably dense 
 cellular tissue, so that the capsule is always removed in connexion with that organ. 
 This relation between the liver and the capsule is much more constant and intimate than 
 that between the capsule and the kidney. A small depression, already described as ex- 
 isting on the lower surface of the liver, to the right of the vena cava ascendens, is in- 
 tended for the reception of the capsule. 
 
 On the left side the capsule is in immediate relation with the pancreas, and is indirect- 
 ly connected with the spleen and the great end of the stomach. 
 
 The posterior surface is in contact with the highest part of the pillars of the diaphragm, 
 opposite the tenth dorsal vertebra. The great splanchnic nerves and the semilunar 
 ganglia are situated behind, and on the inner side of the capsules, to which they send off 
 so many branches, that Duvernoy regarded these organs as the ganglia of the renal nerves. 
 
 Their convex, thin, and slightly sinuous border, is directed inward and upward. Their 
 concave border is thick, and almost always deeply grooved. The surface of the capsules 
 is invested by a thin layer of fat, which it is extremely difficult to remove, on account 
 of the numerous fibrous and vascular prolongations that pass into it from the capsule ; 
 certain furrows, either containing vessels or not, and varying in depth and extent, trav- 
 erse the surface of this organ, especially in front. 
 
 Cavity. — It is still doubtful whether the supra-renal capsules have a cavity in their in- 
 terior, as their name would seen to indicate. It is certain that in the greater number 
 of subjects, on dividing them in different directions, they are found to consist of two 
 laminae applied to each other, and united as by an adhesive substance, a sort of dark- 
 coloured, false membrane ; and that these laminaj are reflected inward opposite the con- 
 cave border, so as to form a projection like a cock's comb in the interior of the capsule. 
 The colour of the external surface is yellowish, or, rather, mottled with large yellow and 
 brown spots. The internal surface, or, rather, of the parts which are in contact, is chest- 
 nut brown, or bistre colour of different shades, so that I am induced to compare its ap- 
 pearance with that of an apoplectic cyst. It seems as if in this, as in the other case, 
 blood had been effused, and then absorbed. 
 
 The internal surface is also rough, and, as it were, lacerated ; a sort of yellowish or 
 chestnut-coloured pulp may be scraped off it. I have seen roundish, pulpy vegetations 
 jpringing from several parts of this surface, sections of which presented a yellowish 
 colour, mottled with brovra. 
 
 The name of atrabiliary capsules, given to them by Barthohn, is undoubtedly derived 
 
 * Eustachius, who first described them, called them glanduUt qua renibus incumbunt. 
 
446 SPLANCHNOLOGY. 
 
 from the deep brovm colour of their internal surface. That anatomist regarded them as 
 small pouches or capsules, and thought that they were the reservoirs of the blackish 
 fluid (sanguis niger, Bartholin; succus atrabiliaris, atramentum glandulosum, Lecat.) to 
 which the ancients gave the name of atrabilis. 
 
 Structure. — The supra-renal capsules consist of two substances : one external or cor- 
 tical, yellowish, and striated, which forms almost the whole thickness of the capsule ; 
 and an internal or central portion, presenting the appearance of a soft layer of a deep 
 chestnut brown colour, and traversed by numerous vessels. The striated arrangement 
 of the cortical layer, which is so easily seen in large animals, is frequently effaced in the 
 human subject, where the capsule appears reduced to a thin yellowish lamella, folded 
 back upon itself The lobular character of the surface is only apparent, and depends 
 upon the furrows formed in it for the vessels. The granular structure, admitted by most 
 of the authors who have called these organs glands, has not been clearly demonstrated. 
 
 A fibrous membrane, anedogous to the proper coat of the kidney, covers the supra-renal 
 capsules. 
 
 The capsular arteries are very numerous and very large, in proportion to the size of the 
 organ ; they are divided into the superior, arising from the phrenic, the middle, proceed- 
 ing directly from the aorta, and the inferior, furnished by the renal arteries. The ■veins 
 are very large, and soon pass into the vena cava ; the anterior furrow is chiefly intend- 
 ed for them. It h^ls been supposed that they open directly into the cavity of the capsule, 
 on account of the faciUty with which this latter may be distended by injecting air or any 
 fluid into the veins. But it is probable that in such cases laceration has occurred. The 
 veins of the right capsule enter the vena cava inferior directly ; those of the left enter 
 the renal vein of the same side. The lymphatic vessels are little known. The veins are 
 very numerous ; they are derived directly from the semilunar ganglia and solar plexus, 
 and also from the renal plexus. It is in vain to search for the excretory duct, admitted 
 by several anatomists ; and described by some as entering the pelvis of the kidney, and 
 by others as terminating in the testicle in the male, and in the ovary in the female. 
 
 Development. — The supra-renal capsules are relatively much larger in the foetus than 
 in the adult, and they are remarkable in this respect, that their size is inversely propor- 
 tioned to that of the kidneys. They are distinct as early as the second month of intra- 
 uterine life, and at that time exceed the kidney both in weight and size. This predom- 
 inance continues during the whole of the third month ; at the fourth, the kidneys and 
 the supra-renal capsules are of equal size ; at the sixth month, the capsules are not more 
 than half as large as the kidneys ; at birth, not more than one third. Tlie existence of 
 a cavity is not more evident in the foetus than in the adult. 
 
 In the aged, the supra-renal capsules are sometimes very large, and their colour is al- 
 ways yellow at this period of life. 
 
 Uses. — The uses of the supra-renal capsules are unknown ; we are even ignorant 
 whether they should be classed lunong the glands. The great number of vessels with 
 which they are supplied, and the numerous nerves distributed upon them, suiEciently 
 prove that something more than mere nutritive changes must occur within these organs. 
 Their pathological anatomy, which still remains to be investigated, may perhaps throw 
 some light upon this obscure point of physiology. 
 
 THE GENERATIVE ORGANS. 
 
 The generative apparatus presents this remarkable peculiarity, that the organs of 
 which it is composed are divided between two individuals of the same species ; and from 
 this division results the difference of sex. 
 
 The male sex is chiefly characterized by the faculty of producing a fecundating fluid, 
 the spermatic fluid, or semen. The female sex is characterized by the faculty of produ- 
 cing certain ovules, which become fitted for the reproduction of an individual of the same 
 species, as soon as they have been submitted to the fecundating influence of the fluid 
 secreted by the male. The female sex is also characterized, in the human species, and 
 in all mammalia, by the possession of a gland (the mamma), which is intended to provide 
 nutriment for the newly-born creature. 
 
 The genital organs occupy the lower extremity of the trunk ; they are situated in con- 
 tact with the termination of the digestive canal on the one hand, and of the urinary organs 
 on the other, with the latter of which they have the most intimate connexions, especial- 
 ly in the male. 
 
 THE GENERATIVE ORGANS OF THE MALE. 
 
 The Testicles and their Coverings. — The Epididymis, the Vasa Deferentia, and VesiculeB 
 Seminales. — The Penis. — The Urethra. — The Prostate and Cowper^s Glands. 
 The genital organs of the male consist of a secreting and an excretory apparatus, com- 
 posed of the following parts : two glands, called the testicles ; two provisional excretory 
 canals, the vasa deferentia ; two reservoirs for the spermatic fluid during the longer or 
 
THE TESTICLES. -447 
 
 shorter intervals between the periods of its expulsion, named the vestcula seminales ; 
 and certain ultimate excretory canals, the ejaculatory ducts and the urethra. To this lat- 
 ter canal is annexed an erectile structure, which enables it to assume the condition ne- 
 cessary for the ejection of the fecundating fluid ; together, they form the pe7iis. The 
 prostate gland and Cmcper's glands yield secretions, the use of which is connected with 
 the generative functions : they may be regarded as appendages of the urethra. 
 
 The Testicles and their Coverings. 
 
 The Coverings of the Testicle. 
 
 The coverings of the testicle consist of several layers, which, reckoning from without 
 inward, are the scrotum, the dartos, the tunica erythroides, the fibrous coat, and the tu- 
 nica vagin£ilis. There is a sixth testicular covering, named the tunica albuginea ; but, 
 as it forms an integral part of the testis, we shall describe it with that organ. 
 
 The scrotum,* or cutaneous covering of the testicles, is a sort of pouch or bag common to 
 both of those organs ; the skin of which it is composed exhibits the following peculiarities : 
 
 It is of a browner colour than that of other parts of the body, so that, in some individ- 
 uals, a layer of colouring matter, similar to that existing in the negro, may be demonstra- 
 ted beneath it ; like the skin of the penis and the eyelids, it is very thin, on account of 
 the tenuity of its chorion ; it is much larger than is needed for containing the testicle ; 
 it is provided with scattered and obliquely inserted hairs, the follicles of which are large, 
 and project upon the surface ; and, lastly, its external aspect presents many varieties : 
 thus, it becomes flaccid and elongated under the influence of warmth, and in old and en- 
 feebled persons, while, during youth, in the robust, and under the influence of cold, it 
 becomes contracted, wrinkled, and closely applied to the testicle. 
 
 The scrotum is divided into two equal halves, by a sort of median line or ridge, caUed 
 the raphe, from the Greek word fidnru, to sew ; because the two halves of the skin ap- 
 pear to be united at this part, as it were, by a seam. 
 
 The object of the great extent of the skin of the scrotum is, perhaps, to enable it to 
 cover the penis when in a state of erection. 
 
 The dartos is a reddish filcunentous tissue, traversed by a great number of vessels, 
 which can be easily seen through the skin of the scrotum. This tissue envelops both 
 testicles, and furnishes a prolongation interposed between them, and forming the septum 
 of the dartos. Upon the sides, and opposite the spermatic cord, the dartos terminates 
 abruptly, and is replaced by adipose cellular tissue. In front it is continued around the 
 penis ; behind, it is prolonged upon the median line, by an angular extremity, as far as 
 the sphincter ani. 
 
 It follows, therefore, that there is only a single dartos, within which are contained 
 both testicles, a septum alone intervening between them. This separation in the mid- 
 dle line has led some to follow Ruysch, in describing a distinct dartos for each testicle. 
 The dartos is closely united to the skin of the scrotum by its external surface, and it is 
 very loosely connected by extremely delicate cellular tissue, with the subjacent cover- 
 ings, upon which it glides with the greatest freedom. 
 
 With regard to its structure, the dartos, at first sight, presents some analogy to cellu- 
 lar tissue, but it differs from it essentially in its aspect ; for in no situation does ceUular 
 tissue exliibit distinct reddish nodulated filaments, like those of the dartos. It is true 
 that these filaments are irregularly interlaced, but the majority of them peiss in a verti- 
 cal direction ; and when a single fibre is examined, we are struck with its analogy to 
 muscular tissue. t It also differs in its vital properties : thus, the dartos possesses the 
 property of active contractility, as is seen in the contraction of the scrotum, and the ver- 
 micular motions observed in persons exposed to cold, or under the influence of great 
 dread, or of the venereal orgasm, and also in the much more evident contraction of the 
 scrotum after an irritating injection has been thrown into the cavity of the tunica vaginalis. 
 
 It is, therefore, intermediate between cellular and muscular tissue, and might be call- 
 ed the dartoid tissue. It was, for a long time, supposed to be confined to the scrotum, 
 but it is met with in many other parts, viz., the vagina, the substance of the nipple, and 
 the parietes of the veins, of which it seems to me to form the external coat. 
 
 Some anatomists regard the dartos as nothing more than the remains of the guhcrnac- 
 tdum testis ; but, in the first place, the dartos is found in the foetus, before the descent 
 of the testicle ; and in an adult whose testicle had not escaped from the external ab- 
 dominal ring, I satisfied myself that the gubernaculum and the dartos existed separately 
 and independently of each other, t 
 
 * From the Latin word scrotum, a sac, or purse of leather. The Greek term for the same part is S/rxM") 
 and hence the word oscheocele, which serves to designate every tumour developed in the scrotum. 
 
 t [According to M. Jordan (Miiller's Archives, 1834), the tissue of the dartos is composed of uniform cylin- 
 drical filaments, which resemble those of cellular tissue in diameter, but are larger than the varicose fila- 
 ments of voluntary muscular fibre, and smaller than the involuntary muscular fibres, excepting those compo- 
 sing the iris. They resemble cellular tissue, and not muscle, in their chemical characters, and difT^r from the 
 fonner only in presenting a reddish aspect, and in being arranged into longitudinal fasciculi, instead of inter- 
 lacing in all directions.] 
 
 t The specimen from which this statement is taken has been presented to the anatomical society hy M. Manec 
 
448 SPLANCHNOLOGY. 
 
 The dartos has also been incorrectly regarded as a continuation of the superficial Jascta 
 (see Aponeukology). 
 
 The Tunica Erythroides. — This name (derived from the Greek word kpvdph^, red) is 
 given to a thin membrane, formed by an expansion of the fibres of the cremaster. It is 
 very well marked in the young and vigorous, but becomes partially atrophied in the aged.* 
 
 We have already seen (vide Obliquus Internus Abdominis, Myology) that the cremas- 
 ter is essentially formed of fibres arising directly from the groove of the crural arch, on 
 the outer side of the inguinal canal. The loops formed by the lower portions of the ob- 
 liquus internus and transversalis are, where they exist, completely distinct from it. The 
 cremaster and the tunica erj^hroides, which is an expansion of it, are the agents of the 
 sudden upward movement of the testicle, which is very distinct from the slow vermicu- 
 lar motion resulting from the action of the dartos. In a patient whose urethra was ex- 
 tremely irritable, I found that the introduction of a bougie was followed by a sudden and 
 long-continued elevation of the testicles, with a separation of their lower ends. This 
 movement was entirely independent of the dartos and scrotum, which remained flaccid 
 and pendent in front of the thighs. 
 
 Wlien the cremaster reaches the testicles, it expands into a number of fasciculi, dis- 
 tributed over the surface of the fibrous coat, and inserted, in the lower animals, by well- 
 marked tendinous fibres, which, however, I have never been able to discover in man. 
 In hydrocele, these fibrous bundles resemble small cords, which, as Sir A. Cooper ju- 
 diciously remarks, may be mistaken for veins. 
 
 The Common Fibrous Coat. — This membrane is very distinct from the tunica vagina- 
 lis, which lines its inner surface ; it forms a common covering for the testicle and the 
 spermatic cord ; it is thin and transparent, narrow along the cord, and expanded below, 
 so as to cover the testicle. At the inguinal ring it divides into two laminae, one of 
 which, almost always incomplete, is attached to the circumference of the ring, while the 
 other seems to be prolonged within the canal, where it is, however, very difficult to fol- 
 low it. Modern anatomists regard this fibrous tunic as a prolongation of the fascia trans- 
 versalis, which would be dragged down with the testicle during its descent. 
 
 The Tunica Vaginalis, or Serous Coat. — The tunica vaginalis is a shut sac, and pre- 
 sents two portions : one, parietal (p, fig. 183), lining the fibrous coat ; the other, reflected 
 or testicular {v), which covers the testicle, without that organ being contained within 
 the sac. 
 
 The intimate union of the serous and fibrous coats of the testicle affords an example 
 of a fibro-serous membrane, analogous to the dura mater and the pericardium. As the 
 reflection of the tunica vaginalis upon the testicle takes place at a variable height, it 
 follows that a greater or less portion of the cord is covered by this coat. 
 
 The arrangement of the tunica vaginalis on one side of the epididymis differs from 
 that on the other. On the outer side it immediately invests the epididymis, is then re- 
 flected from it, becoming applied to the part reflected from the opposite side of the epi- 
 didymis, and forms a cul-de-sac, by which the middle of that body is completely separa- 
 ted from the upper border of the testicle. At the bottom of this cul-de-sac are some 
 small openings, leading into a back cavity. It forms, therefore, a fold like the mesen- 
 tery, at the middle of the epididymis, the two ends of which, however, are closely ap- 
 plied to the testicle. On the inner side it rises higher upon the cord than on the outer 
 side, and is separated from the epididymis by the vas deferens and the spermatic ves- 
 sels. It is easy to detach it from the fibrous coat, where it is reflected upon the testi- 
 cle, but it adheres closely to the epididymis and to the tunica albuginea. 
 
 Its internal surface, free and smooth, exhales a serous fluid, the morbid accumulation 
 of which constitutes the disease called hydrocele. In most animals the tunica vaginalis 
 communicates with the peritoneum at aU ages ; but in man this communication exists 
 normally only during intra-uterine life. After birth the two cavities are perfectly dis- 
 tinct. If, from any cause, this separation is not completed, the tunica vaginalis may 
 form either a hernial sac, containing displaced intestines, or a cyst containing serous fluid 
 effused from the abdomen. In the former case, the disease is called congenital hernia, 
 in the latter congenital hydrocele. 
 
 The Testicles. 
 
 The testicles (testes) are two glandular organs, intended to secrete the spermatic fluid. 
 They are situated in the scrotum, at the sides of and below the penis, and are, there- 
 fore, exposed to external violence. They are supported by their coverings, and by the 
 cord formed by the spermatic vessels, and are at a greater or less distance from the in- 
 guinal ring, according as the dartos and cremaster are in a state of relaxation or con- 
 traction. 
 
 The testicles are not situated at exactly the same height, the left descending a little 
 lower than the right. This arrangement, which has not escaped the observation of 
 
 * The cremaster is extremely well developed in the stallion ; in which animal it is easy to establish the 
 distinction between this muscle and the lower fibres of the internal oblique, the loops of which do not exist in 
 all subjects. 
 
THE TESTICLES. 449 
 
 painters and sculptors, assists in protecting them from injury by enabling them to glide 
 one above the other when the thighs are closely approximated, and thus to avoid com- 
 pression. Their situation is not the same at all periods of life. In the foetus, they are 
 contained within the abdominal cavity. Sometimes they remain permanently, or much 
 longer than usual in that situation, which, in the natural state, is merely temporary. 
 
 Number. — The varieties in the number of the testicles are most of them only appEirent. 
 Thus, for example, in almost all monorchides (persons having but one testis : from fiovog, 
 single, and bpxi-u a testicle), that testicle which is absent from the scrotum is situated 
 in the abdomen. Nevertheless, I have had occasion to dissect an individual who had 
 only one testicle ; there was an atrophied vesicula seminalis on the side where the tes- 
 ticle was wanting ; the vas deferens commenced at this vesicle, and was lost upon the 
 side of the bladder. I was not able to examine the spermatic vessels. The examples 
 of three, four, or five testicles are not well attested.* An epiploic, or fatty tumour, or 
 a cyst, may have been mistaken for a testicle. 
 
 Size. — The testicles vary in size in different individuals, and still more at different 
 ages. At the period of puberty, the testicle, which up to that time had been, as it were, 
 in a state of atrophy in comparison with the rest of the body, increases greatly in size. 
 This atrophy, which is normal before puberty, may continue to a more advanced age. 
 In a subject about twenty years of age, in which the penis and larynx were highly de- 
 veloped, I found the two testicles atrophied : they weighed less than a drachm ; the 
 epididymis, although it was atrophied, was larger than the body of the testicle. 
 
 The two testicles are not exactly of the same size : the left is generally larger than 
 the right ; but this difference is so slight and inconstant, that some anatomists have 
 even thought that a shght predominance may be observed in the right. 
 
 The following are the average dimensions of the testicle : Length, two inches ; breadth, 
 one inch ; thickness, eight lines. 
 
 Weight. — According to Meckel, the weight of the testicle is four drachms ; according 
 to Sir Astley Cooper, one ounce. 
 
 Consistence. — It is extremely important, especially in a practical point of view, to 
 judge of the natural consistence of the testicle. The character of this consistence is 
 determined less by the proper substance of the testicle than by the degree of tension of 
 its immediate covering ; and in this respect the consistence of the testicle very much 
 resembles that of the eye. In the aged, the seminiferous ducts being empty, the testi- 
 cle becomes soft, and, as it were, atrophied. It would be still less consistent, if it were 
 not for the serous fluid with which the cellular tissue between these ducts becomes in- 
 filtrated. 
 
 Figure, Direction, and Relations. — The testicle is oval, but flattened at the sides. This 
 form, added to the polished and slippery character of its surface, enables it easily to 
 avoid compression. The long diameter or axis of the testicle is directed obliquely down- 
 ward and backward ; its lateral surfaces and its lower borderf are convex, free, smooth, 
 and constantly lubricated by the serosity of the tunica vaginalis. The upper Border is 
 straight ; it is directed backward, is embraced by the epididymis, which surmounts it 
 like the crest of a helmet, and is covered by the tunica vaginalis in a small portion only 
 of its extent. The spermatic vessels enter at the inner part of this border, and behind 
 the head of the epididymis. The anterior extremity of the oval is the larger, and is di- 
 rected upward and forward ; the posterior extremity is turned backward and downward. 
 The white colour of the surface of the testicle is owing to its proper fibrous covering, 
 which, on account of its whiteness, is called the tunica albuginea. 
 
 Structure. — The constituent parts of the testicle are a fibrous membrane, a proper tis- 
 sue, and certain vessels and nerves. 
 
 The fibrous membrane, tunica propria sive albuginea, is white, strong, and inextensible ; 
 it is analogous to the sclerotic coat of the eye, and, like it, forms the most external coat 
 or shell of the organ which it covers. 
 
 The tunica vaginalis invests the outer surface of the tunica albuginea, excepting op- 
 posite the epididymis, where the fibrous coat is destitute of the serous membrane for a 
 considerable extent. The serous and fibrous layers adhere closely to each other. 
 
 Within the substance of the tunica albuginea, but nearer the internal than the exter- 
 nal surface, are a great number of tortuous vessels, which may be seen through the 
 semi-transparent fibrous layer by which they are covered. These vessels project on the 
 internal surface of the tunica albuginea, so that at first it might be thought that they 
 vvere simply in contact with the membrane, and not within its substance. t 
 
 * 1 have been consulted concerning a child, who appeared to me to have two testicles upon one side, each 
 of which was as large as that of the opposite side ; but it is impossible to decide with certainty upon such a 
 matter until dissection has shown the true nature of pretended supernumerary testicles. Nevertheless, tli« 
 kind of pain felt upon pressing the body imagined to be a testicle may afford tolerably satisfactory indications 
 during life. 
 
 t [M. Cruveilhier differs from mos^ other anatomists in applying the terms upper and lower to the opposite 
 borders of the testicle, instead of posterior and anterior ; on the contrary, he describes the two extremities of 
 this organ as anterior and posterior, instead of upper and lower, as is usually the case.] 
 
 i The existence of numerous vessels within tlie substance of the tunica albuginea has led Sir Astley Coojh 
 
 Ti L L 
 
450 
 
 SPLANCHNOLOGY 
 
 The internal surface of the tunica albuginea is in immediate relation with the proper 
 Fig. 183. substance of the testicle, and is connected with it by a great num- 
 
 / . ber of vascular filaments, which traverse it in all directions, and 
 
 divide it into small masses or lobules, and also by the extension of 
 the substance of the gland itself into oblique culs-de-sac, or cells 
 formed by the tunica albuginea, several of which are a line and a 
 half or two lines deep. When the tunica albuginea is carefully re- 
 moved, filaments of the glandular substance are seen escaping from 
 these small cells, which are most numerous at the upper borders 
 of the testicle. The strength of the vascular filaments which trav- 
 erse the testicle has led to the opinion that they are all enveloped 
 by a fibrous sheath derived from the tunica albuginea, but I have 
 never been satisfied of the existence of these sheaths.* 
 
 At the upper border of the testicle, the tunica albuginea becomes 
 remarkably thickened, and forms the corpus Highmori, or medias- 
 tinum testis ( Cooper). In order to obtain a correct notion of this 
 structure, it is necessary to make a vertical section of the testicle 
 at right angles with its long diameter : we then observe a nucleus (i, fig. 183), or fibrous 
 thickening of a triangular shape, perforated by bloodvessels, but do not at first sight dis- 
 cover any canals in it ; so that we might be inclined to agree with Winslow (who called 
 it the nucleus of the testis) in denying that it contains any canals ; or, rather, with Swam- 
 merdam, in regarding those canals that do exist in it as destined exclusively for the ar- 
 teries and veins. 
 
 If, after dividing the testicle along its convex border, we reflect the tunica albuginea, 
 we shall see that near the upper border the filaments (a a, fig. 184) which constitute the 
 substance of the testicle enter {b b) numerous spaces existing in the tunica albuginea at 
 this part, pass towards the thickening (»') of the upper border, traverse it (c) from its pos- 
 terior to its anterior extremity, and then, uniting together into a greater or less number 
 of tubes, perforate (d) the tunica albuginea opposite the head of the epididymis (e). 
 
 The corpus Highmorianum, moreover, exists only in the anterior half of the upper 
 border of the testicle (see i, fig. 184). All the bloodvessels reach the testicle at this 
 point, and, having entered it there, divide into two sets ; one of these is situated in the 
 substance of the fibrous coat, so as to form its sinuses (the tunica vasculosa), and fur- 
 nishes a multitude of vessels, which are given off from it in succession, and are distrib- 
 uted to the substance of the gland.t Among these vessels, I would particularly notice 
 one tortuous artery which passes from before backward along the upper border of the 
 testicle. The other set of vessels perforate the corpus Highmorianum directly, and pass 
 from the upper to the lower border of the testicle. The corpus Highmorianum, then, is 
 a thickening of the tunica albuginea, which occupies the anterior half of the upper bor- 
 der of the testicle, and is perforated by the filaments composing the proper tissue of the 
 testicle, and also by a great number of bloodvessels. 
 Proper Tissue. — The proper substance of the testicle resembles a soft yellowish pulp, 
 grooved by a multitude of small tense and strong columns, 
 which divide it into a great number of masses or lobules (a a, 
 fig. 184). These small columns are nothing more than the 
 vessels given off from the tunica albuginea.t Each lobule rep- 
 resents a pyramid, the apex of which is directed towards the 
 upper border of the gland, and the base towards its lower bor- 
 der. The lobules consist of a collection of extremely delicate 
 filaments, folded a very gi-eat number of times upon themselves, 
 so as to resemble the granules of glands, and have, in fact, been 
 described as such by some anatomists.^ These filaments are 
 the seminiferous tubes, which were injected by Haller and Mon 
 
 Fig. 184. 
 
 er to describe two layers in it ; an external, which he compared to the dura 
 mater, and an internal (the tunica vasculosa), which he likened to the pia 
 mater, I cannot admit this analog-y. The vessels contained in the tunica al- 
 buginea rather resemble the sinuses of the dura mater than the vascular net 
 work of the pia mater. * See note, p. 421 
 
 t [According to Sir Astley Cooper, many of the arterial vessels pass along 
 the septa, extending from the inner surface of the tunica albuginea to the 
 mediastinum, and then turn back and are distributed upon the lobes. The 
 principal veins arise upon the larger ends of the lobes, pass up to the mediasti- 
 num, and perforate it.] 
 
 t [Sir Astley Cooper has described fibrous columns which extend from the 
 inner surface of the tunica albuginea, and unite with similar prolongations given off from the mediastinum 
 testis, and forming the sides of the cells described by M. Cruveilhier (p. 449). From these columns lateral 
 membranes proceed, so as to form septa between the larger masses of glandular structure, while other finer 
 membranous extensions enclose the small lobes in separate pouches. The larger bloodvessels are supported 
 by the columns, and the smaller ones ramify upon the membranous septa and pouches.] 
 
 4 Riolanus described a fibrous thickening'of the proper coat of the testicle. The description given by High- 
 more is very confused ; he describes a body obscure aut omnid non cavum, which appears to perforate the tu- 
 nica albuginea, and to convey the semen to the epididymis ; he has also represented as opening into this canal 
 • certain parallel vessels, which he considered to be an artery and a vein. 
 
THE TESTECLES. 461 
 
 ro from the vas deferens. I have in vain attempted to perform the same experiment ; 
 the mercury never passed beyond the epididymis. It has been said that each lobule is 
 formed by one or two tubuh, and the number of these tubes has been calculated at 300. 
 Each tubulus is said to be 16 feet long, and -^^o of an inch in diameter. According to 
 Monro's calculation, there would be 5000 feet of tubuli seminiferi in the small space oc- 
 cupied by one testicle. 
 
 If we take hold of the substance of the testicle with a pair of pincers, and then draw 
 it out slowly, we shall raise a number of apparently knotted filaments from the common 
 mass, some of which will break immediately, while others may be drawn out to a foot, 
 a foot and a half, or two feet, without breaking. It is particularly easy to pull out the 
 filaments when the tissue of the testicle is very moist. The little knots disappear du- 
 ring this process, and the tubuli then assume the character of straight and almost trans- 
 parent filaments.* 
 
 The proper tissue of the testicle adheres to the tunica albuginea by the bloodvessels 
 only, excepting near the upper border of the testicle. In this situation the tubuli are 
 lodged in the cells or spaces, already described, in the substance of the tunica albuginea ; 
 they all pass towards the corpus Highmori, traverse it from behind forward, and form 
 within its substance what Haller described as the rete vasculosum testis {,c,figs. 184, 185), 
 because he supposed that the seminiferous tubes in this situation communicated with 
 each other. + 
 
 Lastly, the tubes composing the rete unite into an indeterminate niunber of efferent 
 ducts {d), estimated at from ten to thirty, which perforate the tunica albuginea, opposite 
 the head of the epididymis. 
 
 Vessels and Nerves. — ^The testicular artery, the principal division of the spermatic, di- 
 vides, before entering the testis, into several branches, which pass into the tunica albu- 
 ginea along the upper border of the gland, and are distributed as I have already pointed 
 out when speaking of the corpus Highmori. The veins are very numerous, are arranged 
 in an analogous manner, and form the spermatic veins. The lymphatics are very numer- 
 ous, and are divided into the superficial and deep. 
 
 The nerves are derived both from the ganglionic and the cerebro-spinal system. They 
 have not been traced mto the interior of the testicle, and yet the sensibility of that organ 
 is sufficient evidence of their existence there. 
 
 The serous cellular tissue, by which the seminiferous ducts are united, is so delicate, 
 that it can only be shown bv the aid of a very favourable light 
 
 The Epididymis. 
 
 The epididymis (e /, Jigs. 184, 185) is the vermiform appendage which lies along the 
 superior border of the testicle, like the crest upon a helmet. Its name is derived from 
 its position (enl, upon, 6i6vfiog, the testicle). 
 
 It is so situated that it does not precisely occupy the superior border of the testicle, 
 but encroaches a little upon its outer face (see Jig. 182, a section of the right testis), so 
 that when the tunica vaginalis is opened, and the inner side of the testicle examined, 
 we cannot see the epididymis. It is closely connected with the testicle by its anterior 
 extremity, which is remarkably enlarged, and is called the head, or globus majm- (e) ; its 
 middle portion or body (/) is separated from the testis ; and it again adheres by its pos- 
 terior extremity, called the tail, or globus minor (g) ; which, after being prolonged as far 
 as the posterior extremity of the testis, turns upward, by being reflected upon itself, £md 
 gives origin to the vas deferens (<)• It is flattened from above downward, concave be- 
 low, and slightly flexuous ; its two extremities are covered by the tunica vaginalis only 
 above and on the outside, but its body is completely enclosed by that membrane, which 
 forms a fold for it hke the mesentery. (See Tunica Vaginalis.) 
 
 Structure. — When the tunica vaginalis, which gives the epididymis a smooth appear- 
 ance, is removed (as in^. 185), the latter resembles a cord, so twisted upon itself that 
 it would appear impossible at first sight to disentangle it. This cord is hollow, as may 
 be shown by injecting mercury or a coloured liquid into it through the vas deferens. 
 The canal or duct which forms the epididymis is not unfrequently found distended with 
 semen ; and then we may ascertain by simple inspection, as weU as by injecting it, that 
 it is of a determinate size, and that its parietes are thin and semi-transparent. 
 
 The epididymis is intimately connected with the body of the testicle by its head only ; 
 the other means of attachment between the two parts consisting exclusively of rather 
 dense cellular tissue, and a fold of the tunica vaginahs. The head of the epididymis is 
 united to the testicle by several ducts, the number of which varies from ten to thirty. 
 
 * [The seminiferous tubes are of the same diameter throughout. According to Lauth, they most commonly 
 terminate in loops, and by numerous anastomoses ; in one instance oniy did he observe a free closed extrem- 
 ity. In some animals, Miillcr found the seminal tubes ending in free extremities ; and the same mode of ter- 
 mination was frequently seen by Krause in the human testis. Like the uriniferous tubes, the tubuli seminif- 
 eri terminate, therefore, in two ways.] 
 
 t [Immediately before the tubuli pass into the corpus Highmori to form the rete, they become rather larger 
 xad straight, and are hence called the tubuli recti (d d,fig. 184) : the tubuli composing the rete are stated by 
 Lauth to vary from seven to thirteen ; ihey are tortuous, and, as supposed by Haller, anaston-ose.] 
 
452 SPLANCHNOLOGY. 
 
 rhey form several groups, which emerge from the corpus Highmori, and immediately 
 Fig. 185. afterward become convoluted, so as to form the head or glohun major 
 
 of the epididymis. These vessels, which are called the vasa efferentia, 
 or coni vasculosi (d), are perfectly distinct at their exit from the 
 corpus Highmori ; but, after a short course in the globus major, they 
 unite into a single canal, the numerous convolutions of which consti 
 tute the vermiform body called the epididymis. It is possible, by 
 careful and minute dissection, to unravel this duct, the folds of 
 which, shaped like the figure 8, are united by very dense cellular tis- 
 sue. Monro, who even counted the number of its inflections, has 
 calculated its length to be about thirty-two feet.* 
 
 It is supplied with arteries, and some veins and numerous lymphatics 
 issue from it. Its nerves are derived from the testicular, and accom- 
 pany a small branch of the hypogastric artery, which has been named 
 the deferential artery by Sir Astley Cooper. 
 
 Not unfrequently a dense cord, having the same structure as the 
 vas deferens, is found proceeding from the epididymis ; this cord is 
 the vas aberrans. — {Holler.) 
 
 The supernumerary ducts of this nature, injected with mercury by 
 Haller, extended for a few inches into the cellular tissue of the sper- 
 matic cord. 
 
 The Vas Deferens. 
 
 The vas deferens {t, figs. 181, 184, 186), the excretory duct of the testicle, extends 
 from the epididymis to the ejaculatory duct {fig. 186), which may be regarded as a con- 
 tinuation of it. It conunences at the point where the caudal extremity of the epididymis 
 becomes separated from the testicle. 
 
 The following is a description of its very complicated course : in its first or testicular 
 portion it passes from behind forward and upward along the upper border of the testicle, 
 almost parallel with the epididymis, from the inner edge of which it is separated only 
 by the spermatic arteries and veins. In this first portion of its course the vas deferens 
 pretty closely resembles a braided cord, and is, moreover, folded a great number of 
 times, like the canal of the epididymis. 
 
 The seconA, funicular or ascending portion of the vas deferens, forms part of the sper- 
 matic cord, and passes directly upward towards the inguinal ring. There it is in rela- 
 tion with the spermatic artery and veins, which are placed in front of it, and from which 
 it is perfectly distinct, being surrounded by an independent sheath of filamentous cellular 
 tissue. It is convoluted, at its lower part, for the space of an inch or an inch and a half, 
 but is straight in the rest of its extent. The third or inguinal portion of the vas defer- 
 ens passes through the inguinal canal to enter into tlie abdomen. Like that canal, it is 
 directed obliquely upward, outward, and backward, and is from an inch and a half to two 
 inches and a half in length. The lower margins of the obliquus internus and transver- 
 salis seem to curve over it ; it crosses the epigastric artery at right angles, a little above 
 the bend formed by that artery, where it changes its direction from horizontal to verti- 
 cal; in this portion of its course, as- well as in the preceding, the vas deferens forms 
 part of the spermatic cord. The fourth or vesical portion. — Having arrived within the 
 abdomen, the vas deferens leaves the vessels and nerves, proceeds vertically dovraward 
 into the pelvis, passes along the side {fig. 181) and then the posterior surface {fig. 186) 
 of the bladder, in which position it is retained by the peritoneum, crosses very obliquely 
 the fibrous cord formed by the remains of the umbilical artery, and is then directed in- 
 ward and downward to the inferior fundus of the bladder. Having arrived opposite and 
 internally to the entrance of the ureter into the bladder, it is directed horizontally in- 
 ward and a little forward like the vesicula seminalis {s, figs. 181, 186), internally to 
 which it is situated, and gradually approaches nearer and nearer to its fellow of the op- 
 posite side, with which it seems to be joined. At the anterior extremity of the vesicula 
 seminalis it unites at an acute angle with the efferent duct {c,fig. 186) of the latter, the 
 union of the two forming the ejaculatory duct {d). In its vesical portion, for about two 
 inches above the vesiculae seminales, the vas deferens is considerably dilated, and, at 
 the same time, its parietes become thinner. 
 
 On the inner side of the vesicula seminalis the canal still continues dilated, and is 
 sometimes sacculated, and has a flexuous appearance. Each sacculus is formed by a 
 small ampulla, which opens into the cavity of the canal. 
 
 The vas deferens forms, therefore, in this situation, a sort of provisional reservoir, re- 
 sembling, in its internal aspect and structure, the vesiculae seminales. 
 
 The spermatic cord, or cord of the spermatic vessels, is formed by the spennatic arteryt 
 
 * [The average length of the vasa efferentia is stated by Lauth to be eight inches ; they diminish in size 
 as they approach the canal forming the epididymis, which they enter at intervals of about three and a quajter 
 nches from each other. The length of that canal is, according to the same author, about twenty-one feet.] 
 t [Also the deferential artery, and the cremasteric branch of the epigastric artery.] 
 
THE TESTICLES. 453 
 
 and veins, the lymphatic vessels, the spermatic plexus of nerves, a branch of the genito- 
 crural nerve, and the vas deferens, all being surrounded by the cremaster muscle and 
 the common fibrous coat. 
 
 Structure. — The following are the principal points concerning the structure of the vas 
 deferens : It is harder than any other excretory duct, and it can be recognised by the 
 touch among the other constituent parts of the cord, both in the healthy and in the dis- 
 eased state, in which latter condition it may become considerably enlarged It is per- 
 fectly cylindrical. Its bore is so small that it is almost capillary, and will scarcely admit 
 Mejan's probe. Its parietes are thick, and contrast singularly with the fineness of its bore. 
 
 Several anatomists admit the existence of circular and longitudinal muscular fibres in 
 this duct. Leuwenhoek demonstrated longitudinal fibres, with circular fibres beneath 
 them. All that I have been able to discover in the human vas deferens, even by the aid 
 of the glass, are circular. In their appearance, and kind of cohesion, they present much 
 analogy to muscular fibres ; but it is in the larger animals only, in the horse, for exam- 
 ple, that their muscularity can be clearly ascertained, and that we find distinctly a very 
 thin longitudinal and superficial layer of fibres, with very thick and strong circular fibres 
 beneath. The internal surface of the vas deferens is white, rough, and alveolar ; its 
 roughness is due to small and very white fibrous fasciculi, some of which are directed 
 longitudinally, while others are circular, and which are either regularly or irregularly ar- 
 ranged. 
 
 The mucous membrane lining the vas deferens is so thin that it is difficult to demoQ- 
 strate it. 
 
 The Vesicula Seminales. 
 
 The vesiculae seminales are two membranous pouches, which serve as reservoirs for 
 the semen.* 
 
 They are sitimted {s,fig. 181) between the rectum and the bladder, on the outer side 
 of, and parallel to, the vasa deferentia. As they are di- p. jgg 
 
 rected obliquely inward and forward (s, fig. 186), their an- 
 terior extremities are closely approximated, being separa- 
 ted from each other merely by the width of the vasa defer- 
 entia, while their posterior extremities are very far asun- 
 der ; they thus form two sides of an isosceles triangle, 
 within the area of which the bladder (a) is in immediate 
 relation with the rectum. They are flattened and oblong, 
 and are expanded at their posterior extremities, which 
 sometimes project beyond the inferior fundus of the dis- 
 tended bladder, and always do so when that organ is con- 
 tracted. Their anterior extremities are narrowed, and 
 surrounded by the prostate, and their surface has a saccu- 
 lated appearance. They vary in size, which is not always 
 equal on the two sides ; and they are much larger in the 
 adult than in youth or old age. Their size also varies ac- 
 cording to whether they are empty or full. They are from two inches to two inches 
 and a half long, and abou^ six lines broad, and two or three lines thick. 
 
 Their relations with the bladder and the rectum are not direct ; for they are surround- 
 ed with a filamentous tissue, consisting of transverse fibres, which separates them from 
 the neighbouring parts, and appears to me to be analogous to the tissue of the dartos. 
 
 When divided in various directions, the vesiculae seminales exhibit a collection of 
 cells, communicating with each other, and filled with a yellowish brown, thick, viscid 
 fluid, very different in appearance from semen as ejaculated during life. The sacculi of 
 the external surface, and the cells and septa of the interior of the vesiculae, are formed 
 by the extremely complicated convolution of a sort of intestinal tube, or narrow oblong 
 sac, on which I have never been able to find any appendages, ramifications, or divertic- 
 ula. When unravelled (as at s), its length varies from six to eight inches ; its convo- 
 lutions are attached to each other by fibrous tissue, but they may always be separated, 
 either with or without maceration. I have seen an unfolded vesicle a foot in length ; in 
 other subjects I have seen two distinct pouches on each side, one of which was extreme- 
 ly small. Lastly, the internal surface of the seminal vesicles has the same rough and 
 alveolar appearance as that of the vasa deferentia. 
 
 * [The semen, considered anatomically, consists, according to Wagner, of liquor seminis, seminal granules, 
 and seminal animalcules ; the latter were discovered by Ham, and described by Leuwenhoek. In the human 
 subject, the seminal granules are round granulated bodies, about ^-^Vo'^ '" TbVu'^ °^ ^"^ '"'^^ '"^ diameter ; 
 the seminal animalcules, or spermatozoa, have an elliptical body, about ^.^^^ th to > A ^ th of an inch in di- 
 ameter, and a long caudal filament : their total length is from ^J^th to j-^-^th of an inch : their organization 
 is yet unknown ; but in the spermatozoa of the bear, Valentin has lately observed evidences of a definite in- 
 ternal structure ; they perform very rapid movements, which continue some hours after evacuation or removal 
 from the body. They are not found before puberty, and then only in the vesicuIiE seminales, vas deferens, 
 and epididymis. The semen of the testis contains, besides the seminal granules, certain vesicles or cysts, in 
 which, as shown by Wagner, the future spermatozoa are developed. i 
 
454 SPLANCHNOLOGY. 
 
 The structure of the parietes of the vesicles is also precisely the same as that of the 
 deferent vessels, excepting that the external coat is thinner ; in the larger animals this 
 coat is evidently muscular, and it appears to me to be so in the human subject also. I 
 have in vain attempted to find the glands described by Winslovsr in the substance of the 
 walls of the seminal vesicles. 
 
 Efferent Ducts of the Vesiculcs Seminales. — From the anterior extremity or neck of each 
 vesicle, which we have said is situated in the substance of the prostate, arises a very 
 delicate duct, the efferent duct (c) of the vesicula seminalis : this duct almost immediately 
 unites with the vas deferens, the walls of which are thin and very dilatable in this situa- 
 tion. By the junction of the two, which occurs at a very acute angle, the ejaculatory duct 
 (d) is formed ; this passes through the prostate (which is shown divided in the figure), 
 upward and forward, parallel to and in contact with its fellow of the opposite side, but 
 without communicating with it. The ejaculatory ducts have very thin parietes, but they 
 are tolerably wide, and very dilatable ; closely apphed to each other, they open separately 
 on the enlarged extremity of the verumontanum, one on the right, the other on the left 
 (Jg. 182). 
 
 The Penis. 
 
 The penis, the organ of copulation, is situated in front of the symphysis pubis. When 
 collapsed, it is flaccid, and forms a curve with the concavity looking downward ; but du- 
 ring erection, it is large and hard, and forms a curve with its concavity turned upward. 
 
 It is cylindrical when collapsed, but has a triangular prismatic form, with blunt edges, 
 when in the opposite condition. Two of these edges are lateral, and are formed by the 
 projection of the corpus cavemosum ; the other is anterior, and corresponds with the 
 canal of the urethra. Its posterior extremity is attached to the pubis ; its anterior ex- 
 tremity forms a conical enlargement, called the glans, on which is seen the orifice of the 
 urethra. 
 
 Structure. — The penis consists essentially of the corpus cavemosum and the canal of 
 the urethra, the expanded extremity of which forms the glans penis. Some proper mus- 
 cles are attached to it ; it receives large vessels and nerves, and it is covered by integu- 
 ment. 
 
 The Skin of the Penis and Prepuce. — The skin of the penis has several peculiarities : 
 thus, it is very thin, although not so thin as that of the scrotum and the eyehds. In this 
 respect it contrasts remarkably with the thick hairy skin which covers the- cushion of 
 adipose tissue situated over the symphysis ; it is generally of a browner colour than that 
 of the rest of the skin ; it has no hair bulbs visible to the naked eye ; it is extremely 
 movable, being capable of gliding forward upon the corpus cavemosum, of forming a 
 covering for tumours in the scrotvun, and also of folding upon itself when the penis is re- 
 duced to its smallest dimensions. This great mobility of the skin is owing to the loose- 
 ness of the sub-cutaneous cellular tissue, which is continuous with the dartos, and ap- 
 pears to me to be of the same nature ; like that structure, it never contains fat, but may 
 become infiltrated with serum. 
 
 The Prepuce. — The skin of the penis forms a non-adherent sheath for the glans, upon 
 Avhich it advances, and either projects beyond it or not, according as that part is flaccid 
 or distended. At the free border of this sheath the skin does not terminate abruptly, but 
 is reflected upon itself, assumes the characters of a mucous membrane, and passes back- 
 ward as far as the base of the glans, so as to hne the inner surface of the cutaneous layer. 
 Opposite the constriction or neck surrounding the glans, the mucous membrane or re- 
 flected skin again becomes reflected over the glans, to which it forms a closely adherent 
 covering, and at the margin of the orifice of the urethra becomes continuous with the 
 mucous membrane hning that canal. The non-adherent sheath which covers the glans 
 is called the prepuce.* 
 
 Sometimes the orifice of this sheath is so narrow as to prevent its being easily drawn 
 backward, especiedly during erection. This constitutes what is called phymosis.i Cir- 
 cumcision, an operation which consists in removing an annular portion of the prepuce, 
 was, as we know, a general custom among the Jews, and is now recognised among the 
 operations of surgery. 
 
 The length of the prepuce varies in difierent individuals ; in some it is very short, and 
 only covers one half of the posterior third of the glans. 
 
 The term franum praputii is applied to a triangular fold of mucous membrane, which 
 is reflected from the prepuce upon the furrow on the lower surface of the glans, below 
 the urethral orifice. Sometimes the prolongation of the fraenum as far as the orifice 
 renders erection painful, and requires a slight operation, called section of the fraenum. 
 
 The cellular tissue, between the cutaneous and mucous layers of the prepuce, par- 
 takes of the characters of the sub-cutaneous cellular tissue of the penis ; its looseness 
 
 * [Beneath the mncous membrane covering the constriction behind the corona glandis are situated clusters 
 of small sebaceous glands, named glandule Tysoni, or odorifera.'] 
 
 t When this malformation exists, if the prepuce he drawn back over the base of the glans, it cannot be re 
 turned ; this comlition of the parts, and the sort of strangulation resulting from it, constitutes what is known 
 by the name of para-phymosis. 
 
THE PENIS. 456 
 
 enables the prepuce to be unfolded, and this takes place more or less completely during 
 erection. 
 
 The Corpus Cavemosum. — The corpus cavemosmn, so named on account of its struc- 
 ture, forms the greater portion of the penis ; it commences behind by a bifurcated ex- 
 tremity, forming its roots, or crura. Each root arises immediately on the inside, and 
 above the tuberosity of the ischium, by a very slender extremity, and gradually increas- 
 ing in size, passes forward and inward along the ascending ramus of the ischium and 
 the descending ramus of the pubes, to both of which it adheres intimately. At the sjrm- 
 physis the two roots unite. The triangular interval between them is occupied by the 
 canal of the urethra. 
 
 The corpus cavemosum results, therefore, from the union of two distinct conical 
 roots ; and on this account the older anatomists distinguished two corpora cavernosa ; but 
 the communications existing between its two halves are opposed to any such distinction. 
 
 The corpus cavemosum is cylindrical, and presents a longitudinal groove above, in 
 which are lodged the dorsal vessels and nerves of the penis, and a broad and deep groove 
 below, in which the urethra is situated. The anterior extremity is obtuse, and is em- 
 braced by the base of the glans, with which it does not appear to have any vascular 
 communication. 
 
 Structure. — The corpus cavemosum is composed of a very strong fibrous cylinder, 
 filled with a spongy or erectile tissue. 
 
 The Fibrous Cylinder. — The external coat is of a fibrous nature, and is remarkable for 
 its thickness, which is one or two lines ; for its strength, which is such that the corpus 
 cavemosum will bear the whole weight of the body without breaking, as may be proved 
 experimentally upon the dead body ; and for its extensibility and elasticity, properties which 
 do not belong intrinsically to the tissue itself, but depend upon the areolar disposition of 
 its fibres.* 
 
 Septum of the Corpus Cavemosum. — The interior of the cavernous body is divided into 
 two lateral halves by an incomplete septum, formed of very strong vertical fibrous col- 
 umns, which are much thicker and more numerous behind than in front. This median 
 septum (septum pectiniforme, h, fig. 187), between the two halves of the corpus caver- 
 nosum, is not complete ; it appears to be intended to prevent too great a distension of 
 this part during erection. - 
 
 The Spongy or Erectile Tissue. — An areolar tissue (a a), the meshes of which contain 
 a greater or less quantity of blood, occupies the interior of the fibrous cylinder of the 
 corpus cavemosum. This tissue, which is the chief agent in erection, consists of an 
 interlacement of veins, supported by prolongations or trabecule, given off from the inner 
 surface of the fibrous membrane. 
 
 If air or any fluid be injected into the crura of the corpus cavemosum, the penis will 
 acquire the same size as it has during erection, and the injection will pass readily into 
 the veins ; we may therefore conclude that all the cells of the corpus cavemosum com- 
 municate with each other, and, farther, that they communicate freely with the veins 
 If the corpus cavemosum be distended with tallow, and then, after being allowed to dry, 
 if the injection be dissolved out by hot oil of turpentine, we shall find that the cavernous 
 body presents a spongy stmcture, analogous to that of the spleen. The several grada- 
 tions from tme veins to spongy tissue may be traced in the venous plexus, situated at 
 the root of the penis. At first we find veins communicating with each other laterally, as 
 it were, by perforations ; then the communications become more and more numerous ; 
 and, lastly, in the corpus cavemosum all traces of distinct vessels are lost, and nothing 
 can be detected but a mass of cells, apparently resulting from the anastomoses of veins. 
 The structure of the spongy tissue of the corpus cavemosum is, therefore, essentially 
 venous. 
 
 A transverse section of the corpus cavemosum (^. 187), after it has been prepared 
 in the manner above indicated, exhibits an appearance of cells, 
 somewhat resembling that seen on a section of the body of a ver- 
 tebra ; these cells are bounded by laminae, which appear to be 
 chiefly derived from the lower wall of the corpus cavemosum, on 
 the inner surface of which is found a convexity, corresponding 
 with the groove for the urethra {d). These laminae radiate, as 
 from a centre, to the entire internal surface of the cyhnder, repre- 
 sented by the corpus cavemosum. 
 
 Vessels. — The veins of the corpus cavemosum are extremely 
 large, and are divided into the dorsal veins of the penis and the o'/ 
 proper veins of the cavemous body ; they all pass beneath the 
 symphysis, and are received into fibrous canals, through which 
 they are transmitted into the pelvis. These veins are provided with a great number of 
 valves, so that injections thrown into the trunks cannot pass into the branches. 
 
 * [The outer coat of the corpus cavemosum and the trabecule, in its interior, consist of tendinous fibres, 
 mixed with some elastic tissue. In the penis of the horse there are pale red fibres, differiu? from cellular 
 tendinous, and elastic tissue, but which, according to Miiller, do not possess muscular contractility.] 
 
456 SPLANCHNOLOGY. 
 
 The arteries arise from the internal pudic, and enter the substance of the corpus ca 
 vemosum. Injection of these arteries does not produce erection until the fluid has pass- 
 ed from them into the veins.* 
 
 The lymphatic vessels are little known. 
 
 No nerves have been traced into the interior of the corpus cavemosum.t 
 
 The Triangular Suspensory Ligament of the Penis. — This ligament is composed of yel- 
 low elastic tissue, and extends in the median hne from the symphysis pubis to the cor- 
 pus cavemosum. Muscular fibres have been described as existing in it ; but it is prob- 
 able some fibres prolonged from the bulbo-cavernosus, and now known as the muscle 
 of Houston, have been regarded as forming part of this ligament. I have seen the sus- 
 pensory ligament reach along the linea alba, half way up to the umbilicus. 
 
 Muscles of the Penis. 
 These are eight in number, four on each side, viz., the ischio-cavernosus, the bulbo-ca- 
 vernosus, the pubio-urethralis, and the ischio-bulbosus. 
 
 The Ischio-cavernosus, or the Erector Penis. 
 
 The ischio-cavernosus {c,Jig. 163) is an elongated muscle, situated upon the corre- 
 sponding root of the corpus cavemosum ; it is curved upon itself, and is aponeurotic in 
 part of its extent. 
 
 It arise* from the inner lip of the tuberosity of the ischium, below the transversus pe- 
 rinaei, by tendinous and fleshy fibres, and also from the surface of the root of the corpus 
 cavemosum. From these points its fibres pass inward, and are inserted, after a short 
 course, into the edges of the upper surface of a very strong, shining, and fasciculated 
 aponeurosis, having its fibres directed from behind forward, which covers the correspond- 
 ing root of the cavernous body, upon which it is then prolonged. The fleshy fibres, ter- 
 minating at the edges of the aponeurosis, form two bundles ; one internal, and extend- 
 ing upon the inner side of the root, the other extemal, which passes on the outer side 
 of the same, and is prolonged, much farther than the internal fasciculus, upon the cav- 
 ernous body. In order to see the structure of this muscle, it is necessary to make a 
 longitudinal incision into the aponeurosis, which entirely covers its lower surface ; we 
 then observe a muscular layer, which is tolerabjy thick behind, but thin in front, and is 
 formed partly by the original fibres, and pertly by others arising from the root of the 
 corpus cavemosum itself 
 
 Relations. — Below, with the cellular tissue and the dartos ; above, with the root of the 
 corpus cavemosum, upon which it is closely applied ; on the inside, with the bulbo-cav- 
 ernosus, being separated from it by a triangular space, the base of which is directed 
 backward. 
 
 Uses. — It acts solely upon the corpus cavemosum, drawing the root of the penis down- 
 ward and backward • instead of compressing the root of the corpus cavemosum by the 
 contraction of its fibres, it tends, on the contrary, to dilate its cavity, by separating the 
 wer from the upper wall, and, in this manner, facilitates erection. 
 
 The Bulbo-cavernosus, or Accelerator Urince. 
 
 This muscle {d,fig. 163) is much larger than the preceding ; it is situated in front of 
 the anus, extending along the lower surface of the bulb and the spongy portion of the 
 urethra, upon which it seems to be moulded. 
 
 It arises in front of the sphincter ani by a median fibrous raphe, which is common to 
 the two muscles of this name, and which appears to arise from the bulb, to which it ad 
 heres closely ; while the exteraed fibres arise from the posterior margin of the triangu- 
 lar ligament, or deep perineal fascia, and frequently from the rami of the ossa pubis, op- 
 posite that margin. From this double origin the fibres pass forward, and terminate in 
 the following manner : the outermost fibres form a thin layer upon the lower surface of 
 the triangular ligament, and are inserted by short, tendinous fibres to the inner side of the 
 root of the corpus cavemosum ; the middle fibres, which are larger, are directed oblique- 
 ly inward, and are inserted by very distinct tendinous fibres immediately in front of the 
 jtoint of junction of the roots of the corpus cavemosum, in the sort of groove between 
 that body and the urethra ; the innermost fibres are the longest ; they pass directly for- 
 
 * [Miiller has described, besides the nutritious arteries of the corpus cavemosum, which terminate, as usual, 
 ill the veins, a peculiar set of vessels, called the arterite helicina. They are short, curled branches, much 
 larger than capillaries, and ending abruptly in free rounded extremities ; they project either singly, or in tufts 
 arising ii-om one stem, into the venous cells,by the lining membrane of which they are supported and invested. 
 They are found principally in the posterior portions of the cavernous and spongy bodies, and are more marked 
 in man than in animals. In the horse they are very indistinct ; in the elephant they do not exist at all. Miil- 
 ler believes that the blood, during erection, is poured out directly from these vessels into the venous cells ; 
 but no openings through which the blood could escape have been detected, either in their sides o-- at their ex 
 tremities, nor is analogy in favour of their existence. 
 
 According to Valentin, the so-called helicine arteries are the divided branches of common arteries curled up 
 (after having been injected), in consequence of the retraction of the elastic trabeculie on which they are sup- 
 ported ; to this it is replied, by Miiller, that these vessels may be seen in cells deeper than the surface o; the 
 lection. Valentin farther maintains that the arteries terminate in the veins by wide, funnel-shaped orifices.] 
 
 t [Numerous nerves enter the corpus cavemosum; they arc derived from the internal pudic and sympatheV 
 ic nerves, and have been carefully traced by Mtiller.l 
 
THE URETHRA. 45^ 
 
 ward, and, at the point where the penis is bent in front of the pubis, are inflected out- 
 ward ie,fig. 163), pass upon the sides of the penis, and terminate on its dorsal surface, 
 becoming continuous with the suspensory ligament. Tlie last-named termination ap- 
 pears to me to constitute the muscle described by Houston, which, according to that 
 anatomist, is intended to compress the dorsal veins of the penis* in man and other ani- 
 mals ; but it is evident, on the one hand, that it cannot compress the veins of the penis ; 
 and, on the other, as M. Lenoir has pointed out, that the dorsal veins of the penis are 
 cutaneous veins, which do not communicate with those of the corpus cavemosum.t 
 
 Relations. — I3elow, the bulbo-cavernosus corresponds with the dartos, from which it is 
 separated by the superficial perineal fascia by a very thin layer of fat, and by a proper 
 fibrous sheath. Above, it is in relation with the bulb of the urethra, which it embraces, 
 like a contractile sheath, resembling the sheath around the stems of grasses. The inner 
 border is continuous with the muscle of the opposite side ; so that, at first sight, it might 
 be thought that there is but one bulbo-cavernosus. 
 
 Uses. — Its attachment to the inner side of the corpus cavemosum enables it to separ- 
 ate the lower wall of that body from the upper, and, consequently, to induce the entrance 
 of the blood. It therefore contributes powerfully to erection. On the other hand, by 
 compressing the urethra, it accelerates the expulsion of the urine and semen. 
 
 The Puhio-urethralis. 
 This muscle, known also as the muscle of Wilson, because it was described by that anat- 
 omist, may be regawied as the continuation of the levator ani. The two nmscles arise 
 from the middle of the sub-pubic arch, and descend first upon the sides and then on the 
 lower surface of the membranous portion of the urethra, which they surround as in a 
 ring. They are situated behind the triangular ligament, or deep perineal fascia.t When 
 spasmodically contracted, it is said that they may arrest the point of a catheter. 
 
 The Ischio-bulbosus. 
 We may describe under this name a small muscle situated below the deep perineal 
 fascia. It is stronger than the transversus perinaei ; it arises from the ascending ramus 
 of the ischium and the descending ramus of the pubis, and terminates on the sides of the 
 bulb. This muscle, which is of a triangular shape, is separated from the one last de- 
 scribed by the deep perineal" fascia, so that it cannot be regarded as a dependance of the 
 levator ani.<J 
 
 The Urethra. 
 
 The urethra is the excretory passage for the urine, and in the male it serves the same 
 purpose in regard to the semen. 
 
 Its direction has been particularly studied. Commencing at the neck of the bladder, 
 it passes forward and downward ; having arrived beneath the s3Tnphysis pubis, it de- 
 scribes a slight curve, with the concavity directed upward, embraces the symphysis, ri- 
 ses a little in front of it, and then enters the groove on the lower surface of the corpus 
 cavemosum. Beyond this point its direction is determined by that of the penis ; and it 
 
 * [The compressores venae dorsalis penis, according to Houston (Dublin Hasp. Reports, vol. v.), arise from 
 the rami of the pubes above the erectores penis and the crura of the corpus cavemosum, expand into a thin 
 layer, pass upward, inward, and forward, and unite in a common tendinous band over the dorsal vein. They 
 ftre separated by the crura from the erectores penis, of which muscles, he says, they might otherwise be re- 
 garded as portions : the anterior layer of the triangular ligament and the pudic artery are interposed between 
 them and the muscles of Wilson.] 
 
 t Dissertation sur quelques Points d'Anatomie, de Physiologic, et de Pathologic, No. cccxv., 1833. 
 
 [The dorsal veins return the greater part of the blood from the glans penis and corpus spongiosum, as well 
 as the skin, and are also joined by branches from the corpus cavemosum. (See M. Cruveilhier's own descrip- 
 tion of these veins, Anoeiologt).] 
 
 t [In the description of the muscles given by Wilson himself (Med. Chir. Trans., vol. i., p. 176, 177), it is 
 ■tated, that " the line of tendon connecting the two bellies of these muscles is, in general, very distinctly seen 
 running from the apex of the prostate gland, along the under surface of the membranous portion of the ure- 
 thra, until it enters the corpus spongiosum penis." From this it would appear that the muscles discovered by 
 him are placed between the two layers of the ligament, not behind its posterior layer. 
 
 On the same plane with Wilson's muscles, i. e., between the layers of the ligament, are situated two small 
 transverse muscles, which arise, one on each side, by broad thin tendons, from the rami of the ischia, near 
 their junction with those of the ossa pubis, immediately above the crura penis and their erector muscles ; from 
 thence the fleshy fibres pass transversely inward and upward, and are inserted along the median line of the 
 upper and under surface of the membranous portion of the urethra by means of two tendinous structures, 
 which extend, one above the urethra, from the fascia covering the prostate to the union of the crura penis in 
 frjnt; of the triangular ligament, and the other below that canal, from the fascia on the prostate to the central 
 poirt, of the perineum : to this tendinous structure the vertical muscles of Wilson are also attached. The pu 
 die a'.teries run either above or below these transverse muscles, the lower fibres of which pass below Cow- 
 per's glands, i. e., more superficially, when viewed from the perineum. 
 
 These transverse muscles are described and figured by Santorini (Observ. Anat., c x., I) viii., t. 3, fig. 5, 
 also, Septemdecim Tabula, t. 16, fig. 1), who states, however, that Ihey are attached only to the lower surface 
 of tlie urethra, behind the bulb ; he named them elevatores urethrue, or ejaculatores. It has been recently 
 shown by Mr. Guthrie (Land. Med. and Surg. Journ., 1833, p. 491, 492 ; also, On the Anatomy and Diseases 
 of the Neck of the Bladder and of the Urethra, 1834, p. 34, &c.) that the transverse muscles of Santorini 
 are inserted, as already described, both above and below the urethra ; and that the vertical muscles of Wilson 
 are blended with them at their insertions : he therefore proposes to regard them as one muscle, which has 
 been termed the compressor urethra:.'] 
 
 ^ [The description of this muscle corresponds exactly with that of the transversus perinmi alter of Albinus.l 
 
 M M M 
 
458 SPLANCHNOLOGY. 
 
 describes, with that organ, a second curve, much more marked than the preceding, hav- 
 ing its concavity directed downward, but only in the state of relaxation, for the curve no 
 longer exists when the penis becomes elongated, either from erection, or from direct 
 traction. 
 
 It follows, therefore, that, except during erection, the urethra describes two curves, 
 like the letter S ;* but when the penis is elongated, it forms only a single curve, which 
 is permanent. 
 
 Although the curvature of the urethra is not so rigid as to prevent the introduction of 
 a straight instrument into the bladder, it would be wrong to conclude that the canal it- 
 self is straight. It must be remembered that organic membranous ducts are sufficiently 
 pUable to accommodate themselves to the direction of instruments introduced into them ; 
 but the effacing, or the artificial removal of the curves, is very different from their non- 
 existence. Moreover, the curvature of the urethra is demonstrated by the impossibility 
 of drawing a straight line from the neck of the bladder, and passing a short distance be- 
 low the symphysis to the point where the urethra joins the corpus cavernosum ; also by 
 the curve acquired by bougies after remaining for some time in the urethra ; and, lastly, 
 by the curvature presented by a mould obtained by injecting the bladder and urethra 
 with any substance capable of becoming solid. 
 
 Dimensions. — The length of the urethra is from eight to nine inches ; it is sometimes 
 less than eight. The extreme dimensions noticed by Whately,t in measurements taken 
 from forty-eight subjects, are nine inches six lines and seven inches six lines. It is dif- 
 ficult to estimate the width of the urethra. According to Home, it is four lines, except 
 at the orifice, where it is only three. It is quite impossible to judge of its width exter- 
 nally, on account of the thickness of its walls, and especially on account of their being 
 unequal. The extreme dilatability of the canal allows the introduction of instnmients 
 of considerable caliber, as in the operation of lithotrity. 
 
 The urethra is considered as divided into three portions, as different in their structure 
 as in their relations ; these are the prostatic, the membranous, and the spongy portions. 
 
 The Prostatic Portion. — This part of the urethra, which forms, as it were, a continua- 
 tion of the bladder, and the commencement of the urethra, is called prostatic, because it 
 appears to be hollowed out of the glandular body called the prostate, the description of 
 which must be inserted here, on account of its intimate connexion with the urethra. 
 
 The prostate {i,fig. 181), a whitish glandular body, is situated in front of the neck of 
 the bladder, and embraces it ; it is behind the symphysis pubis, and in front of the rec- 
 tum. It is shaped like a cone, with its base turned backward, and its truncated apex 
 forward. Its axis or long diameter is horizontal, but slopes a little from behind down- 
 ward and forward. It has often a bi-lobed appearance in man, but it is never truly 
 double, as in a great number of animals. 
 
 The size of the prostate varies greatly in different subjects. The following dimen- 
 sions have been taken from the measurements of the prostates of adults : Vertical di- 
 ameter, twelve lines ; transverse, eighteen ; antero-posterior, or length, fifteen. Some- 
 times it acquires three or four times its nominal size ; the increase may affect either the 
 whole gland or one half, or the middle lobe only. 
 
 Relatione. — We shall examine the relations of the prostate with the parts correspond- 
 ing to its outer surface, and with those which are situated within it. 
 
 Relations of the Outer Surface of the Prostate. — The lower surface corresponds with the 
 rectum, adhering to it by tolerably dense celluleir tissue, in which there is never any fat 
 or serum ; and hence"^he rule of examining the prostate by the rectum. In consequence 
 of alterations in the condition of the rectum, that intestine sometimes projects on each 
 side beyond the prostate, as during distension ; and sometimes, as when it is contract- 
 ed, the prostate projects beyond it laterally. The lower surface of the gland is smooth, 
 and is traversed in the median line by an antero-posterior furrow, which is well marked 
 in some subjects, and divides it into two equal portions. 
 
 The upper surface is in relation with the recto-vesical fascia {q,fig- 1^1)> <""' rather, 
 with some very strong ligamentous bundles, which extend from the pubes to the blad- 
 der, and are called the ligaments of the bladder. This surface has no immediate rela- 
 tions with the arch of the pubes, behind which it is placed ; it is always some lines dis- 
 tant from it. Nevertheless, by means of a silver catheter or sound, introduced into the 
 bladder, we may draw the prostate under the pubes, and make it project in the perineum. 
 
 The sides are embraced by the levator ani and the levator prostatae. When the prostate 
 is pushed downward by the catheter, its sides are embraced by the circumference of 
 the arch of the pubes, and they then approach very near the trunk of the internal pudic 
 artery. 
 
 The base of the prostate embraces the neck of the bladder, and is prolonged a little 
 upon that organ, so as to surround the vas deferens and the neck of the vesiculffi semi- 
 nales. 
 
 * It was this direction of the canal which suggested to J. L. Petit the idea of making silver bougies, shaped 
 like the letter S, to remain in the passage. 
 t An Improved Method of treating Stricture of the Urethra, 1816. 
 
THE URETHRA. 43^ 
 
 The apex terminates behind the membranous portion of the urethra. 
 
 Relations of the Prostate vsith the Parts situated in its Interior. — The prostate is perfo- 
 rated by the urethra, by the ejaculatory ducts, and by its own excretory ducts. 
 
 The relations of the urethra with the prostate vary in different subjects : thus, sometimes 
 its lower three fourths only are surrounded by the gland, which is accordingly wanting 
 above, and is merely grooved, not perforated by a canal ; sometimes the prostate forms 
 a complete hollow cylinder around the urethra. The portion of the prostate situated 
 above the urethra is scarcely ever thicker than the part beneath it. In some cases, 
 however, the urethra has been found occupying the lower part of the prostate, and only 
 separated from the rectum by a very thin layer of glandular substance. When such is 
 the case, the rectum is very liable to be wounded in the different steps of the operation 
 of lithotomy.* 
 
 In the natural state the prostate does not project into the urethra ; but not unfrequent- 
 ly we find a prominence, of greater or less size, rising from the lower part of the urethra, 
 opposite the base of the prostate, and obstructing more or less completely the com- 
 mencement of that canal : this tubercle was named by Lieutaud la luette visicale {uvula 
 vesica) ; by Sir Everard Home, an enlargement of the middle lobe of the prostate. But, 
 in the first place, this prominence only exists in disease ; and, secondly, there is no 
 middle lobe, unless that term be applied to the slightly-grooved, and, therefore, thinner 
 portion by which the two lateral halves of the prostate are united. 
 
 Relations of the Ejaculatory Ducts with the Prostate. — The ejaculatory ducts (d,fig. 
 186), which lie close to each other, are received into a sort of conical canal, formed in 
 the prostate. Some loose cellular tissue separates them from the substance of the gland, 
 of which they are altogether independent ; it was chiefly to the portion of the prostate 
 which is situated above this canal that the name middle lobe was given by Home. 
 
 Density. — The density of the prostate is considerable, and yet the tissue of this gland 
 is friable, and can be very easily torn after having been once divided. It is of the greatest 
 importance to remember this friability in performing the operation of lithotomy. The 
 prostate, in fact, is the only obstacle to the extraction of the calculus ; and when this 
 gland has been divided in its antero-posterior diameter, the bladder itself may be torn 
 with the greatest facility. 
 
 Structure. — The structure of the prostate can only be properly studied in the adult. 
 In certain cases of hypertrophy without alteration of tissue, its characters are, as it 
 were, exaggerated. It consists of a collection of glandular lobules, which may be subdi- 
 vided into granules pressed close to each other in the midst of a tissue that appears to 
 me to be muscular, for it is continuous with the muscular coat of the bladder, and bears 
 the most perfect resemblance to it in cases of hypertrophy. From these granules, which 
 are generally of unequal size, small excretory ducts proceed, and unite into an irregular 
 number of prostatic ducts that open, not upon the verumontanwn itself, but upon its sides 
 {see fig. 182), in the whole extent of the lower wall of the prostatic portion of the ure- 
 thra, or prostatic sinus. I have assured myself of the existence of these ducts and their 
 orifices in many cases where I have found them filled with innumerable small calculi, 
 resembling grains of brownish sand. The orifices of the prostatic ducts may be easily 
 detected by pressing the gland, when the fluid secreted by it will be observed to exude 
 at several points. 
 
 The Membranous Portion. — The membranous portion of the urethra (c,fig. 181) ex- 
 tends from the prostatic portion to the bulb, and passes upward and forward.! It is in 
 relation above and laterally with the arch of the pubes, from which it is separated by 
 some considerable veins, or, rather, by a sort of erectile tissue ; below it corresponds 
 with the rectum, but is separated from it by a triangular space, having its base directed 
 forward and downward, and its apex backward and upward. It is generally in this tri- 
 angular space that the urethra is divided in the operation of lithotomy. 
 
 Its upper concave surface is about an inch long ; its lower surface is from four to six 
 lines. This difference in length is caused by the bulb projecting backward upon the 
 lower surface of the membranous portion of the urethra. 
 
 This part of the canal is embraced laterally and below by the two muscular bundles 
 which have been already described as the muscles of Wilson ; and also by the transverse 
 muscular fasciculi described by Santorini and Guthrie. 
 
 The Spongy Portion. — The spongy portion {I) constitutes the greatest part of the length 
 of the urethra ; it commences opposite the symphysis pubis by a very considerable ex- 
 pansion, called the bulb (below I), and terminates at the extremity of the penis by an- 
 other and still larger expansion, which constitutes the glans penis. 
 
 * The varieties in the situation of the urethra, in relation to the prostate, were yreU pointed out by M. 
 Senn, in an inaugural dissertation in 1825. According to his observations, the portion of the prostate situ- 
 ated below the canal is seven or eight lines thick in the middle, and ten or eleveu lines when measured down- 
 ward and outward. 
 
 t [The membranous portion perforates both layers of the triangular ligament, about an inch below the arch 
 of the pubes {see Jig. 138) ; but as the two layers are separated from each other below, the greater part of 
 this portion of the urethra is included between them ; a very small part is situated behind the posterior laver 
 both layers are prolonged over the urethra, one forward and tlie other backward.] 
 
400 ' SPLANCHNOLOGY. 
 
 The hdb occupies the highest part of the pilbic arch, and fills the interval between the 
 crura of the corpus cavemosum. Its size varies in different individuals, and according 
 to the state of the penis ; it projects several lines below the level of the membranous 
 portion, which is partially covered by it in this direction, and seems to open into its up- 
 per part. 
 
 As the bulb is directed very obliquely upward and forward, we might be inclined to 
 consider the urethra to be much more curved than it actually is, if we judged of it only 
 by the external appearance of the canal. 
 
 The bulb is embraced below and upon the sides by the bulbo-cavernosi muscles, which 
 have numerous points of insertion upon it. Between these muscles and the bulb we 
 find Cowper's glands. The bulb terminates insensibly in front, becoming continuous 
 with the spongy portion : the angle of union of the crura of the corpus cavernosum may 
 be assigned as its anterior boundary. 
 
 The Glands of Cowper. — These are two small, rounded bodies (g g,figs. 168, 181, 182) 
 (so called after the anatomist who has given the best description of them), situated 
 against the bulb, in contact with which they are retained by a tolerably dense layer of 
 fibrous tissue.* From each of these glands, which are of variable dimensions, an excre- 
 tory duct proceeds, and after a course of an inch and a half or two inches, opens into 
 the canal of the urethra upon the sides of the spongy portion (c, fig. 182), passing ob- 
 liquely through its parietes.t 
 
 In front of the bulb, the spongy portion of the urethra enters the groove on the lower 
 surface of the corpus cavernosum, and is in relation below, in the first part of its course, 
 with the bulbo-cavernosi muscles, which separate it from the cellular tissue of the scro- 
 tum, and more anteriorly with the skin of the penis. 
 
 The glans, so called from its shape, is the conical enlargement which forms the ex- 
 tremity of the penis. It is covered by the prepuce, which is united to it below by means 
 of the fraenum ; its base projects considerably beyond the end of the corpus cavernosum, 
 and forms what is called the corona glandis. This circular projection is grooved perpen- 
 dicularly throughout its entire extent by some large nervous papillae, which are visible 
 to the naked eye. The base of the glans is cut very obliquely, so that its upper surface 
 is twice as long as its lower. Below, and in the median line, the corona glandis pre- 
 sents a groove, in which the fraenum is received. 
 
 At the extremity of the glans is situated the orifice of the urethra, meatus urinarius, 
 a vertical fissure, three or four lines in extent, and placed in the same line as the frae- 
 num, from which it is separated by a very short interval. Sometimes this orifice is 
 placed exactly opposite the fraenum, and, like it, is directed downward : this malforma- 
 tion constitutes what is called hypospadias. 
 
 Internal Surface of the Urethra. — Upon this surface (see fig. 182) we find no trace of 
 the distinction established between the different portions of the urethra, considered from 
 without, except that the prostatic portion of the canal is of a white colour, while all the 
 rest of it is of a more or less deep violet hue. 
 
 Dimensions. — Opposite the prostate the urethra becomes dilated, sometimes to a con- 
 siderable extent (sinus prostaticus) ; at the commencement of the membranous portion 
 it suddenly contracts, and then continues cylindrical as far as the glans, where it again 
 dilates so as to form the fossa navicularis (o), and terminates by an orifice, which is the 
 narrowest part of the entire canal.J 
 
 In order to obtain more exact ideas of the comparative dimensions of the different 
 portions of the urethra, M. Amussat inflated this canal, and then carefully removed all 
 the structures superadded to its proper parietes, so as to reduce the latter to the mu- 
 cous membrane only, and thus leave them of almost unifonn thickness, instead of being 
 very unequal. According to this mode of appreciation, which, however, is not free from 
 objection, he has shown that the narrowest part of the canal is the bulbous, not the 
 membranous portion ; that the canal, after being contracted opposite the bulb, again ex- 
 pands at the spongy portion, and then gradually contracts as it proceeds forward. He 
 denies the existence of a dilatation opposite the fossa navicularis ; and attributes the 
 dilated appearance of that part to the fact of the tissue of the glans being very dense, 
 and closely adherent to the mucous membrane of the urethra, so as not to allow it to 
 collapse, like that of the other parts of the canal. 
 
 However, the extreme dilatability of the walls of the urethra render an exact deter- 
 mination of its dimensions less important than might be imagined. 
 
 Besides the extensibility of the tissues, there is another anatomical condition which 
 favours the extreme dilatabihty of the urethra, viz., the existence of longitudinal folds 
 on the inner surface of the canal, which are effaced by distension. These folds must 
 
 * [They are placed between the two layers of the triangular ligament : the transverse musrles of Santorini 
 cover them below, am Jhe arteries of the bulb (e e,Jig. 168) cross above them : they are compound glands.] 
 
 t I have never seen the gland called, by Litre, the anti-prostatic ; nor have I seen the third gland of Cow- 
 per, which is said to be situated below the arch of the pubes. 
 
 i [Three dilatations in the urethra are usually described, viz., the prostatic sinus, the sinus of the bulb, and 
 the fossa navicularis. The first and the third of these are described above ; the second is at the commenco 
 ment of the soongy portion, in the inferior wall of the urethra.! 
 
THE OVARIES. 461 
 
 not be confounded with certain small longitudinal fasciculi which lie beneath the mu- 
 cous membrane throughout the whole extent of the canal, and appear to me to be of a 
 muscular nature. The whole of the inner surface of the urethra presents a nmnber of 
 oblique orifices, which lead into culs-de-sac of variable depths. These sinuses, the ori- 
 fices of which are always directed forward, are sometimes large enough to receive the 
 extremities of bougies ; they were very well described by Morgagni, and, therefore, they 
 are generally called the sinuses of Morgagni. I have seen them more than an inch long. 
 No glands open into them.* 
 
 The Verumontanum, or Crest of the Urethra. — The lower wall of the membranous por- 
 tion of the urethra presents, in the median line, a crest, which has been named the ve- 
 rumontanum, caput gallinaginis, or urethral crest {a to d). This crest commences in front 
 by a very delicate extremity ; is directed backward along the median line, and termi- 
 nates at the anterior part of the prostatic portion by an enlarged extremity (a), upon 
 which the ejaculatory ducts open by two distinct orifices. From this posterior extrem 
 ity several radiated folds proceed on either side, called the frcena of the verumontanum, 
 which are lost in the opening of the neck of the bladder ; they were carefully described 
 by Langenbeck. The prostatic ducts open at the sides of the verumontanum. 
 
 Structure of the Urethra. — ^A very fine transparent mucous membrane, of an epidermic 
 character, lines the inner surface of the urethra ; and is continuous, on the one hand, 
 with the mucous membrane of the bladder, and, on the other, with that covering the 
 glans. It is also continued through the ejaculatory ducts, into the vasa deferentia and 
 the vesiculae seminales.f 
 
 The structure of the urethra, as regards the coats external to the mucous membrane, 
 is not the same in the different portions of the canal. 
 
 In the prostatic portion, we find the same elements as in the bladder, which seems as 
 if it were continued into the cavity of the prostate. The deepest layer of the muscular 
 coat of the bladder is prolonged between the mucous membrane and the prostate, while 
 the other layers form different planes which penetrate into the substance of the gland. 
 
 The membranous portion would be more correctly denominated the muscular part of 
 the canal, for it is surrounded by a layer of muscular fibres. A plexus of veins sur- 
 rounds these muscular fibres. 
 
 The spongy portion Q f,fig. 182; c,fig. 187) has a similar appearance to that of the 
 cavernous body ; it is an erectile structure, composed of a fibrous framework, formed by 
 numerous prolongations interlaced in all directions, so as to resemble areolar tissue. It 
 is probable that the internal coat of the veins lines all the cells, which contain more or 
 less blood, according to the state of the penis. 
 
 In the tissue of the corpus spongiosum, as well as in that of the corpus cavernosum, 
 are found longitudinal muscular fibres, very evident to the naked eye in the larger ani- 
 mals, and the existence of which appears to be shown by the microscope in the human 
 subject. The structure of the glans (//) is exactly the same as that of the bulb, only 
 its tissue is more dense. The corpus spongiosum urethrae does not communicate with 
 the corpus cavernosum, although at first sight it appears to be nothing more than a con- 
 tinuation of it. The blunt extremity of the corpus cavernosum is evidently embraced 
 by the base of the glans, but no communication exists between the erectile tissue com- 
 posing these two bodies, so that it is possible to inject them separately. 
 
 THE GENERATIVE ORGANS OF THE FEMALE. 
 
 The Ovaries. — The Fallopian Tubes. — The Uterus. — The Vagina. — The Urethra. — The 
 
 Vulva. 
 The genital organs of the female consist of the ovaries, the Fallopian tubes, the uterus, 
 the vagina, and the several parts forming the vulva. With these we may include the 
 mammae, as appendages to the generative apparatus. 
 
 The Ovaries. 
 
 The ovaries {ovaria), so called on account of the small vesicular ova which they con- 
 tain, are the representatives of the testicles in the male ; the product secreted by both 
 the one and the other is absolutely indispensable for reproduction. From this analogy 
 between the ovaries and testes the ancients called them testes muliebres (Galen). 
 
 The ovaries (a a, fig. 188) are two in number, and are situated one on each side of the 
 uterus, in that portion of the broad ligament {d d') termed the posterior ala (J), and be- 
 hind the Fallopion tube. They are retained in this position by the broad ligament, and 
 by a proper ligament called the ligament of the ovary (c). 
 
 * [One of these sinuses or lacunae, larger than the rest, and situated on the upper surface of the fossa na- 
 vicularis, is called the lacuna magna ; they appear to be mucous crypts.] 
 
 t [It is prolonged into the ducts of Cowper's glands and the prostate, into the vesiculiE seminales, vasa def- 
 erentia, and tubuh seminiferi, and through the ureters into the uriniferous ducts ; in the female it also linei 
 the vagina, uterus, and Fallopian tubes ; the whole forms the genito-urinary system of mucous membranes ; it 
 is covered throughout with an epithelium, which, in the male generative apparatus, approaches the columnar 
 form.] 
 
462 SPLANCHNOLOGV. 
 
 Then situation varies at different ages, and also according to the state of the uterus. 
 In the foetus, they are placed in the lumbar regions, like the testicles. During pregnan- 
 cy they are carried up into the abdomen with the uterus, upon the sides of which they 
 are applied. Immediately after delivery, they occupy the iliac fossae, where they some- 
 times remain during the whole period of life, being retained there by accidental adhe- 
 sions. It is extremely common to find them thrown backward,* and adhering to the pos- 
 terior surface of the uterus. 
 
 The ovary has sometimes been found in inguinal or femoral hernise : by descending 
 into the labia majora, they have simulated the appearance of testicles. 
 
 The size of the ovaries varies according to age, and according as the uterus is gravid 
 or unimpregnated, healthy or diseased. They are relatively larger in the foetus than in 
 the adult ; they diminish in size after birth, again increase at the period of puberty, and 
 become atrophied in old age. During the latter periods of pregnancy, they sometimes 
 acquire double or triple their ordinary size. 
 
 The ovaries are of an oval shape, a little flattened from before backward ; they are of 
 a whitish colour ; their surface is rough, and, as it were, cracked, and is often covered 
 with very dark-coloured cicatrices, which have been incorrectly regarded as remains of 
 ruptures in their external coat, to allow of the escape of the fecundated ovum. 
 
 The ovary is free in front, behind, and above, but is attached by its lower border to the 
 broad hgament, by its outer end to the trumpet-shaped extremity of the Fallopian tube, 
 and by its inner end to the corresponding side of the uterus, some lines below the upper 
 angle of that organ, by means of a ligamentous cord, called the ligament of the ovary (c) ; 
 which was for a long time regarded as a canal {ductus ejaculans), intended to convey an 
 ovarian fluid into the uterus. The tissue of this ligament strongly resembles that of the 
 uterus, and seems to be a prolongation from it. I 
 
 Structure. — The ovary is composed externally of a dense fibrous coat, covered by the 
 peritoneum, which adheres so closely to it that it cannot be detached ; and, internally, 
 of a spongy and vascular tissue, the areolae of which seem to be formed by very dehcate 
 prolongations from the external coat ; in the midst of this tissue (the stroma, from arpufia, 
 a bed) the Graafian vesicles are deposited. These vesicles vary in number, from three or 
 four to fifty. The structure of the ovary is most evident in the recently-delivered fe- 
 male. At that time its tissue, expanded, and, as it were, spongy, appears to me to re- 
 semble that of the dartos, and is traversed by a great number of vessels. I have also 
 seen, in recently-delivered females, the ovaries from twelve to fifteen times larger than 
 usual, and converted into a sac, having very thin parietes, which were easily torn ; the 
 ovary itself was of a spongy, vascular, and diffluent texture, in the midst of which the 
 vesicles were seen unaltered. 
 
 The vesicles are nothing more than small cysts of variable size, with very thin trans- 
 parent walls, adhering to the tissue of the ovary, and containing a hmpid serosity, either 
 colourless, or of a citron yellow. According to Von Baer, the most superficial vesicles 
 which approach the expanded extremity of the Fallopian tube, contain a floating body, 
 which was imperfectly seen by Malpighi, and constitutes the germ or ovum. J 
 
 I have often metvdth ovaries destitute of vesicles ; but then they had undergone some 
 change, that of induration, for excunple. May the absence of these vesicles be regarded 
 as a cause of sterility 1 
 
 The corpora lutea, according to the observations of Haller, consist of the remains of 
 vesicles that have been ruptured in consequence of the act of impregnation ; they are 
 brownish-yellow masses, of a tolerably firm consistence, and which I have found as large 
 as a cherry-stone in females recently delivered. These bodies have been ascertained to 
 exist in females who have never borne children, and this anomaly has been explained by 
 supposing that they may be produced in consequence of masturbation. We would re- 
 mark, however, that there is no constant relation between the existence of these bodies 
 and the occurrence of fecundation. In some females who have had many children, no 
 corpora lutea can be detected, and, on the other hand, a corpus luteum has been found 
 in a girl of five years of age. 
 
 The bloodvessels and veins of the ovary correspond exactly with those of the testicles. 
 
 * The situation of the ovaries, behind the Fallopian tabes, prevents their displacement forward. 
 
 t It has even been stated that this so-called efferent duct of the ovary divides into two branches, one of 
 which opens directly into the uterus, while the other runs along its border, and opens near the os uteri. 
 
 t [The vesicles of De Graaf vary from the size of a pea to that of a pin's head ; they have two tunics, ono 
 external and vascular, the other called the ovi-capsule, which, according to Schwann, is lined internally with 
 epithelium (membrana granulosa, Bair). In each vesicle there is usually but one ovum, which at first occu- 
 pies its centre, but in the mature condition approaches the inner surface of its internal coat, and, sunounded 
 by a granular covering (tunica granulosa, Barry), is held there by retinacula (Barry). The ovum is a perfect- 
 ly spherical body, of uniform size (about y^th of an inch in diameter) ; it consists of a thick but very trans- 
 parent coat (zona pellucida, Valentiri ; chorion, Wagrier), which surrounds the sul)stance of the yolk ; within 
 the yolk is situated the germinal vesicle of Purkinj6 (about yg-jrth of an inch in diameter), and within that 
 the germinal spot of Wagner (about-g-^^th or g-rWth of an inch). The changes incidental to impregnation, 
 according to Dr. Barry, commence in tlie germinal spot and vesicle. For farther information, and for a list of 
 works upon this subject, see Milller''s Physiology, translated by Dr Baly, and Wagner's Physitlogy, trausla- 
 tpd by Dr. Willis.] 
 
THE FALLOPIAN TUBES. 
 
 463 
 
 Uses. — Without precisely determining the part performed by the ovaries in reproduc- 
 tion, it may be said that they are indispensable to that function. Extirpation of these 
 bodies is followed by sterility. And, again, ovarian foetation proves that fecundation 
 may occur within the ovary. The use of the Graafian vesicles in generation is not well 
 known.* 
 
 The Fallopian Tubes. 
 The tula uterina {ff,fig- 188) are two ducts, situated in the substance of the upper 
 margin of the broad ... ,„ 
 
 Ugament. They are t^-vsa. 
 
 also called the tubae 
 rallopianae,+ the Fal- 
 lopian tubes, after 
 Fallopius, who first 
 gave a good descrip- 
 tion of them ; they ex- 
 tend from the upper 
 angle of the uterus to 
 the sides of the cavity 
 of the true pelvis. 
 
 Situation and Di- 
 rection. — Floating, as 
 it were, in the cavity 
 of the pelvis, between 
 
 the ovaries behind, and the round ligaments (^ g) in front, they pass transversely out- 
 ward, and at the point where they terminate, bend backward and inward, in order to 
 approach the outer end of the ovary, to which they are attached by a small ligament. 
 Each Fallopian tube is straight in the inner half of its course, but describes certain wind- 
 ings in the remaining outer portion, which are so considerable in certain cases, and 
 especially when the tube has been the seat of chronic inilammation or of dropsy, as to 
 resemble in some degree the windings of the vas deferens. Moreover, accidental adhe- 
 sions of the expanded extremity very frequently give it an entirely different direction 
 from the one it usually takes. The tubes may be drawn down with the ovaries into a 
 hernial sac, as I have several times observed. 
 
 The length of the Fallopian tube is four or five inches, but it sometimes varies on the 
 two sides. The canal in their interior is very narrow along their inner half, but gradu- 
 ally enlarges as it proceeds outward to their termination, which is expanded and divided 
 into irregular fringes, like the calyces of certain flowers ; this expanded end constitutes 
 the mouth of the trumpet, or the fimbriated extremity (e) of the Fallopian tube. In order 
 to obtain a good view of this structure, it is necessary to place the tube in water, and 
 then a number of fringes or small shreds of unequal length will be seen floating in the 
 liquid, and consisting of folds divided unequally, and sometimes forming two or three 
 concentric circles. It is generally said that one of these fringes, longer than the rest, is 
 attached to the outer end of the ovary ; but this connexion appears to me to be effected 
 by means of a small ligament. All these folded fringes terminate around a circle some- 
 what narrower than the adjoining portion of the tube ; this circle constitutes the free 
 orifi.ce, or ostium abdominale of the tube. 
 
 The outer portion of the tube will admit the end of a moderate-sized catheter, while 
 the inner portion will scarcely admit a bristle. The diameter of that portion of the tube 
 which traverses the uterine walls is capillary, and it is very difficult to detect with the 
 naked eye its uterine orifice, or ostium uterinum (o o, fig. 189). As the canal of the tube 
 opens into the uterine cavity on the one hand, and into the cavity of the peritoneum on 
 the other, it forms a direct communication between the two ; and hence certain cases of 
 peritonitis have been supposed to depend upon the passage of a fluid from the uterus 
 into the peritoneal sac. Not very unfrequently the fimbriated orifice of the tube is ob- 
 literated ; in this case the tube becomes dilated like a cone, having its base directed out- 
 ward, and it also becomes much more flexuous. 
 
 When opened longitudinally, and placed under water, the outer or wide portion of the 
 tube presents longitudinal folds of unequal breadth, and touching by their free edges. 
 
 There is no valve, either in the course or at the orifices of the tube. Its narrow jior- 
 tion is hard to the touch, inextensible, and closely resembles in appearance the vas def- 
 erens ; its wide portion is collapsed, and its walls are thin and extensible. 
 
 Structure. — The peritonium adheres closely to it, and forms its outer coat ; it is lined 
 by a mucous membrane, which can be easily shown in the whole extent of the broad and 
 folded portion, and appears to form of itself the longitudinal folds already described. 
 This lining membrane is continuous, on the one hand, with the uterine mucous mem- 
 brane, and on the other, with the peritoneum, at the fimbriated extremity of the tube ; 
 it thus presents the only example in the human body of the direct continuity of a serous 
 
 * See note, p. 462. t [Literally, the Fallopian tnimpeU, from their expanded abdominal extremities.! 
 
464 SPLANCHNOLOGY. 
 
 and mucous membrane. Between the peritoneal and the mucous coats is found a proper 
 membrane, which appears to be a prolongation of the tissue of the uterus, and is proba- 
 bly muscular.* 
 
 Uses. — The Fallopian tubes, which represent in the female the vasa deferentia in the 
 male, serve not only to transmit the fecundating principle of the male, but also to con- 
 duct the fecundated ovum into the uterus. These uses are proved by the sterility of 
 females in whom the tubes have been tied ; and by the occurrence of tubal fcEtations, in 
 which the fecundated ovum is arrested in the cavity of the tube, and thei'e passes 
 through the several stages of development. 
 
 The fimbriated extremity of the tube is intended to embrace the ovary during the act 
 of fecundation, and to apply itself to the spot from which the ovxun is to be detached ; it 
 follows, therefore, that any adhesion of the ovary or of the tube which prevents this, 
 acts as a cause of sterility. 
 
 The Uterus. 
 
 The uterus (uter, a leather-bottle), matrix (mater), or womb, is the organ of gestation. 
 
 It is situated {u,fig. 190) in the cavity of the pelvis, in the median line, between the 
 bladder and the rectum, and is retained in that position by the round and broad ligament 
 on each side, and by the upper end of the vagina below. 
 
 The looseness and extensibility of its connexions enable it to float, as it were, in the 
 cavity of the pelvis, and to be moved to a greater or less extent. The facility with 
 which it can be drawn towards the vulva in certain surgical operations, and its displace- 
 ment during pregnancy, when it rises into the abdomen, are proofs of its great mobility. 
 
 Direction. — Its long axis is directed obliquely downward and backward, i. e., it coin- 
 cides with the axis of the brim of the pelvis. Its direction is liable to frequent varia- 
 tions, the history of which belongs to midwifery ; but one of them, viz., the obliquity 
 downward, and from the right to the left side, is so frequent that it has been regarded 
 as natural, and, according to some anatomists, appears to be connected with the posi- 
 tion of the rectum on the left side of the pelvis. In pregnancy, this inclination is almost 
 constant, and has some relation with the most usual position of the child, viz., that in 
 which the occiput is turned towards the left acetabulum of the mother. 
 
 Number. — The uterus is single in the human species ; it is double in most animals. 
 The cases of double uterus observed in the human subject are nothing more than bifid 
 uteri, or such as are divided by a septum : this state may exist either in the body of the 
 uterus alone, or at the same time in the body and neck, and even in the vagina. 
 
 Size. — The size of the uterus varies according to age, and certain physiological con- 
 ditions peculiar to this organ. It is very small until puberty, and then acquires the size 
 which it subsequently presents. In females who have borne children it never returns 
 to its original size. It becomes enormously enlarged during pregnancy, or from the de- 
 velopment of certain tumours. In old age it becomes atrophied, and is sometimes as 
 small as it is in newborn infants. The following are the measurements of the uterus 
 after puberty : length, two and a half to three inches ; breadth, at the fundus, sixteen to 
 eighteen lines, at the neck six lines ; antero-posterior diameter, or thickness, six lines.t 
 
 Weight. — The weight of the uterus is from six to ten drachms at puberty, an ounce 
 and a half or two ounces in females who have had children. I have seen it from one to 
 two drachms in aged females, in whom it had become atrophied. At the end of preg- 
 nancy the weight of the uterus is from a pound and a half to three pounds. 
 
 Form. — The uterus is shaped like a small gourd, or a pear flattened from before back- 
 ward. It is divided into a body (m), and cervix or neck (A) ; the distinction between these 
 two parts being established by a more or less marked constriction. 
 
 Relations. — These must be studied in front, behind, on the sides, at the upper border 
 or fundus, and at the lower or vaginal extremity. 
 
 The anterior surface is covered by the peritoneum in its upper three fourths, and is in- 
 directly in relation with the posterior surface of the bladder, from which it is often sep- 
 arated by some convolutions of the small intestine ; in its lower fourth it is in imme- 
 diate contact with the inferior fundus of the bladder, and is united to it by rather loose 
 cellular tissue. The latter relation explains why cancerous affections of the uterus so 
 often extend to the base of the bladder. 
 
 The posterior surface is entirely covered by the peritoneum, and is in relation with the 
 anterior surface of the rectum, from which it is often separated by some convolutions 
 of the small intestine. This surface is much more convex than the anterior ; it may be 
 examined from the rectiun. 
 
 Its sides are slightly concave, and give attachment to the broad ligaments (d d', d d'), 
 which are two quadrilateral folds of peritoneum, extended transversely from the lateral 
 
 * [Muscular fibres have not yet been demonstrated in the human subject, though in some animals circular 
 and longitudinal contractile fibres have been found. The epithelium of the mucous membrane is columnar and 
 ciliated : by the action of the cilia the contents of the tubes are urged towards the uterus : Dr. Heul6 has 
 found cilia on both surfaces of the fimbrise.] 
 
 t [The body of the uterus, at its thickest part, viz., immediately below the fundus, is from eight to twelTe 
 lines thick.] 
 
THE UTERUS. 465 
 
 borders of the uterus to the sides of the pelvis. Their upper margin is divided on each 
 side into three folds or ridges, formed in the following manner : a posterior fold formed 
 by the ovary (a) and its ligament (c), an anterior one by the round ligament (g), and a 
 middle fold by the Fallopian tubes (/). Hence some anatomists have described threr 
 wings {alee vespertilionis) in each of the broad ligaments. 
 
 The broad ligaments may be regarded as forming across the cavity of the pelvis a 
 transverse septum, within which the uterus and its appendages are contained. This 
 septum divides the cavity into two portions : one anterior, containing the bladder, the 
 other posterior, in which are situated the rectum, and almost always some intestinal 
 convolutions. 
 
 Besides the broad ligaments, there are also the ligaments of the ovary and the round 
 ligaments, proceeding from the sides of the uterus. 
 
 The round ligaments {g g) have a fibrous appearance, but are evidently continuous 
 with the tissue of the uterus. They arise from the side of the uterus, below and in 
 front of the Fallopian tubes, pass upward and outward in the anterior fold of the broad 
 ligament to the abdominal orifice of the inguinal canal, into which they enter, being ac- 
 companied by a prolongation of the peritoneum, which forms around them a cylindrical 
 sheath called the canal of Nuck. In females far advanced in life, this sheath may be 
 traced as far as the external orifice of the inguinal canal. 
 
 Besides the uterine fibres which enter into its composition, the round ligament also 
 contains a great number of veins, which may become varicose, especially near the ex- 
 ternal orifice of the inguinal canal, where they sometimes simulate a hernia. 
 
 The upper border or fundus (i) of the uterus is convex, and is directed upward and for- 
 ward ; it is covered by convolutions of the small intestine ; when not distended, it never 
 reaches as high as the brim of the pelvis, and cannot, therefore, be felt by the fingers in 
 the hypogastric region. 
 
 The lower or vaginal extremity of the uterus, called also the os tincce, from its shape, is 
 directed downward and backward ; it is embraced by the vagina, into which it projects, 
 and is divided by a transverse fissure into two lips, one anterior, the other posterior. 
 The OS tinccR is small, and perforated by an almost circular opening {n) in females who 
 have not borne children ; but in those who have been mothers it forms a more consid- 
 erable projection, and its fissure is more marked and longer transversely.* In some 
 females the os tinea; is of considerable length, and, as it were, hypertrophied, although 
 the uterus is healthy. 
 
 The anterior lip is thicker than the posterior, which is a little longer than the other. 
 It frequently happens that in old females every trace of the lips of the os tincae disap- 
 pears ; the orifice alone remains, and in some cases even that is obliterated. In such a 
 case the vagina terminates in a cul-de-sac, at the bottom of which a round and yielding 
 point may be felt. This disappearance of the two lips is much more common than the 
 elongation of the neck of the uterus, which was pointed out by my venerable colleague, 
 M. Lallemand. 
 
 Cavity of the Uterus. — The cavity of the uterus is extremely smeill in comparison with 
 the size of the organ ; its figure is that of a curvilinear triangle ; its walls are in con- 
 tact, and are smooth, and covered with a layer of mucus. We shall examine it in the 
 body and neck of the uterus. 
 
 The cavity of the body of the uterus (w, fig. 189) is of a triangular form, and has an 
 opening at each angle. The inferior opening {ostium internum, k) Fig. 189. 
 establishes a free communication between the cavities of the body 
 and neck ; it is often obliterated in old women, t The other two 
 orifices (o o) are those of the Fallopian tubes ; they are scarcely 
 visible to the naked eye, and are situated at the bottom of two 
 fiuinel-shaped cavities formed at the superior angles of the uterus, 
 and constituting the remains of the division of the body of the ute- 
 rus into two halves or comua. This division, which is normal in 
 many animals, is sometimes met with in the human female. 
 
 Congenital deficiency of the cavity of the uterus is very rare. My colleague. Profes- 
 sor Rostan, kindly sent me a specimen, in which there was no trace of a cavity in the 
 body of the uterus, although the cavity of the neck remained. The female to whom it 
 belonged had never menstruated. It is unnecessary to say that she was barren. 
 
 The cavity of the neck {h to n) represents a cyUnder flattened from before backward, 
 and has upon its anterior and posterior walls certain ridges, which form upon each wall 
 along the whole length of the neck a tolerably regular median column, from which pro- 
 ceed, at more or less acute angles, a certain number of smaller columns,^ which pro- 
 ject to a greater or less degree. The whole appearance resembles that of a fern-leaf, 
 
 * I have seen the os tincse lacerated and fissured in different directions, in consequence of parturition. 
 
 + This obliteration, which causes retention of mucus and blood, and, consequently, distension and ramol- 
 lisa'inent of the body of the uterus, is so common that M. .Mayer regards it as normal. 
 
 t These rugae, which vary considerably in their arrangement. havfi-JlBfin described in detail by Haller, Bo- 
 yer, and others. v»^^-«^ 
 
 N N N 
 
 # 
 
466 SPLANCHNOLOGY. 
 
 and has been called the arbor vita. It generally disappears after the tirst latGtlr, at least 
 only traces of it are left. Nevertheless, it is not unfrequently found perfect, even after 
 several accouchements — a circumstance of some importance in legal medicine. 
 
 The internal surface of the body of the uterus is much more vascular than the neck. 
 This difference is particularly observed in females who have died during a menstrual 
 period, in whom the vessels of the body of the womb are much developed, and that or- 
 gan itself is swollen and softened, while the cervix retains its accustomed whiteness and 
 consistence. 
 
 Another character of the uterine cavity is the existence of a greater or less number 
 of transparent vesicles, which were mistaken by Naboth for ova {ova of Naboth), but are 
 only muciferous follicles. They exist both in the body and neck of the uterus, but are 
 more numerous in the neck, near the vaginal orifice, and only become apparent when 
 the mucus accumulates in them from obliteration of their orifices. They are sometimes 
 much enlarged, and have then given rise to the opinion that some more serious disease 
 has existed. 
 
 The orifices of the uterine sinuses, described by the older anatomists at the fundus of 
 the uterus, cannot be detected. They are only to be seen after delivery in the situa- 
 tion where the placenta had been attached. 
 
 The parietes of the unimpregnated uterus are from four to six lines in thickness. The 
 thinnest part is at the entrance of the Fallopian tubes, where they are not more than 
 two lines thick. The parietes of the cervix are thinner than those of the body. 
 
 Structure of the Uterus. — The constituent parts of the uterus are, a proper tissue, an 
 external peritoneal coat, an internal mucous membrane, and some vessels and nerves. 
 
 The proper tissue is of a grayish colour, very dense and strong, and creaks under the 
 knife like cartilage. The body appears less consistent than the neck, but this depends 
 upon the fact of its being more frequently the seat of sanguineous congestion. It is com- 
 posed of fibres, i. e., it has a linear arrangement. It may be asked, with regard to the 
 nature of these fibres. Do they consist of fibrous tissue 1 are they muscular, or are they 
 analogous to tlie yellow tissue of the arteries 1 The following considerations will de- 
 termine this question : 
 
 The walls of the unimpregnated uterus appear to be composed of a fibrous tissue, trav- 
 ersed by a great number of vessels. During pregnancy, or in consequence of the devel- 
 opment of tumours, or the accumulation of fluid in the cavity of the uterus, its proper 
 tissue acquires all the properties of the muscular tissue, as it exists in the viscera of 
 organic life, and, like it, is endowed with contractility. Can, therefore, the presence 
 of a foetus or a foreign body in the uterus cause a transformation in the tissue of that 
 organ 1* Assuredly not ; but the great influx of blood into the uterus, and the conse- 
 quent distension and development of its fibres, reveals a structure which before was con- 
 cealed by the state of condensation and atrophy kept up by inactivity. 
 
 This view is fully confirmed by the microscopical observations of Rtederer, and the 
 chemical experiments of Schwilgue ; and also by the results furnished by comparative 
 anatomy, which has shown circular and longitudinal muscular fibres in the uteri of some 
 animals, even when not in a gravid condition, t 
 
 The nature of the fibres of the uterus being determined, we may now examine their 
 direction. Some anatomists agree with Malpighi and Monro, that they have no regu- 
 larity in their disposition, but are interlaced in an inextricable manner. It must be con- 
 fessed that, in the unimpregnated uterus, such is the case ; but during gestation, the ar- 
 rangement of the greater number of fibres can be traced. J 
 
 In the body the external thin layer is composed of two median vertical fasciculi, one 
 on each surface of the uterus ; of another fasciculus occupying the fundus, and of some 
 oblique ascending and descending fibres, which converge towards the Fallopian tubes, 
 the round ligaments, and the ligaments of the ovaries, which contain prolongations of 
 these fibres.^ This first, or superficial layer, belongs exclusively to the body of the ute- 
 rus. The deep layer of the body consists of two series of circular fibres ; each series 
 forming a cone, the apex of which corresponds to the Fallopian tube, while the base is 
 directed towards the median hne, and is there blended with that of the opposite side. 
 
 The neck is composed entirely of circular fibres, which intersect each other at very 
 acute angles. 
 
 The facts furnished by comparative anatomy perfectly accord with the preceding de- 
 scription Thus, in the uterus of a sow, which had httered, I found that the cervix was 
 composed exclusively of circular fibres ; and that the cornua (aduterum of M. Geoffrey 
 
 * I conceive that I have proved by facts, that only three tissues, viz., the muscular, the nervous, and the 
 glandular, are never the products of organic transformations. — (Vide Essai sur VAnalomie Pathol., 1816.) 
 
 t CThe muscular fibres of the gravid uterus have been described by Dr. Baly (translation of MUller's Phys- 
 iology). Like other inorganic muscular fibres, they have no transverse striae ; they arc much broader than 
 those of the alimentary canal, and taper very much at their extremities, which are sometimes split into two 
 or three points : the corpuscles upon them are comparatively small.] 
 
 X Hunter, Analomia uteri. Rosemberger in Schlegel, ^yllog. Oper. Minor, ad Arlem Obstetric. Lipsis, 
 \om. ii., p. 290. M6moire pnisentt i 1' Academic de M6decine, par Mmc. Boivin. Oct., 1821. 
 
 ft I. c, in the i,'ravid state. 
 
THE UTERUS. 467 
 
 St. Hilaire), which represent the body of the uterus of the human female, were formed 
 by two layers of fibres, one external and longitudinal, the other deep and circular. From 
 this arrangement, we may therefore conclude that the human uterus results from the union 
 of two comua, which communicate directly with each other, instead of opening separ- 
 ately into the cavity of the cervix. 
 
 When examined in the state of pregnancy, the tissue of the uterus is found to be trav 
 ersed by venous canals, or uterine sinuses, which are of very considerable size, especial- 
 ly opposite the attachment of the placenta. This great number of vessels gives to the 
 tissue of the uterus the appearance of an erectile or cavernous structure, having muscu- 
 lar parietes.* 
 
 The External or Peritoneal Coat. — ^The peritoneum, after covering the posterior surface 
 of the bladder, is reflected upon the anterior surface of the uterus, of which it covers 
 only the upper three fourths, the lower fourth being in immediate contact with the blad- 
 der. At the fundus of the uterus, it passes to the posterior surface, which it covers en- 
 tirely, is prolonged a short distance upon the vagina, and is then reflected upon the rec- 
 tum. The broad ligaments are formed by a transverse duplicature of this coat. Two 
 falciform folds, formed by this membrane between the bladder and the uterus, are called 
 the vesico-uterine ligaments, and two others, between the uterus and the rectum, are na- 
 med the recto-uterine ligaments. 
 
 The peritoneum adheres very loosely to the borders of the uterus, but much more 
 closely as it approaches the median line. When enlarged during pregnancy, the uterus 
 becomes covered with the peritoneum of the broad ligament, a species of mesentery, the 
 folds of which become separated, and yield to the increasing size of the organ. 
 
 The Internal or Mucous Membrane. — The existence of a mucous membrane upon the 
 internal surface of the uterus has been denied by those anatomists who have examined 
 it after parturition, especially by Morgagni and Chaussier, and so, also, by those who do 
 not admit the presence of a mucous membrane unless it can be demonstrated over a 
 certain space. But the existence of a mucous membrane on the internal surface of the 
 uterus appears to me incontestably proved by the following considerations : 
 
 First, every organized cavity which communicates with the exterior is hned by a mu- 
 cous membrane ; why, therefore, should the uterus form an exception to this rule ! Sec 
 ondly, by dissection it is shown that the mucous membrane of the vagina is continued 
 into the neck of the uterus, and then into the body ; but in this latter situation it is des- 
 titute of epithelium.! Notwithstanding the difficulty of dissecting this membrane, on 
 account of its tenuity, and its close adhesion to the tissue of the uterus, its presence is 
 demonstrated by the following observations : Under the microscope, the internal surface 
 of the uterus presents a papillary appearance, but the papillae are very small ; it is pro- 
 vided with follicles or crypts, from which mucus may be expressed by a number of 
 points, and which form small vesicles w^jen distended with mucus, in consequence of 
 obstruction or obliteration of their orifices. Thirdly, it is extremely vascular, and pre- 
 sents a capillary network of the same appearance as that of the other mucous mem- 
 branes ; and, lastly, it is constantly lubricated with mucus. Pathological observations 
 Eilso show that the internal surface of the uterus, like all raucous membranes, is liable to 
 spontaneous hemorrhages from exh2dation, without breach of continuity, to catarrhic 
 secretions, and to those growths which are denominated mucous, vesicular, and fibrous 
 polypi : and it is generally admitted that, where there is an identity of disease, there is 
 also identity of structure. 
 
 During pregnancy, the elements of the mucous membrane are separated; the vessels 
 become penicillate, and greatly increased in size ; but in proportion as the uterus returns 
 to its original dimensions, the mucous membrane regains its primitive form, and its dis- 
 sociated elements approach each other. It seems as if this membrane was destroyed 
 by a true exfoliation, and then entirely reproduced. 
 
 The arteries of the uterus are derived from two sources : the principal, called the ute- 
 rine, arise from the hypogastric ; the others proceed from the spermatic or ovarian ar- 
 teries to the borders of the uterus, and are distributed upon it : both sets are very tor- 
 tuous. 
 
 The veins are remarkable for their enormous size during pregnancy and after parturi- 
 tion. The term uterine sinuses has been given to the large veins which are then found 
 in the substance of the organ ; and this term is not altogether without foundation, for 
 these venous canals are formed by the lining membrane of the veins which adheres to 
 the proper tissue of the uterus, just as, in the sinuses of the dura mater, it adheres to 
 the fibrous tissue of that membrane. 
 
 The lymphatics, which have been well examined only during pregnancy and after par- 
 
 * This combination of the erectile and muscular tissues is found in the penis of the horse, and perhaps, 
 also, in that of man. 
 
 t [The mucous membrane of the uterus contains numerous tubular glands, or crypts, resembling, in form 
 and direction, the tubuli of the stomach, and the crypts of Lieberkuehn, found in the intestinal canal. The 
 epithelium of this mucous membrane is, according to Henl6, columnar, and also ciliated from the fundus to 
 the middle of the cervix uteri ; below that point it passes into the squamous form of epithelium found in the 
 ragina and on the labia.] 
 
4§8 SPLANCHNOLOGY. 
 
 turition, at which time I have often seen them full of pus, are, like the veins, extremely 
 large (see Anat. Path., avec planches, liv. xiv.) ; they form several layers in the sub- 
 stance of the uterus, ^^e most superficial of which is the most developed. They termi- 
 nate in the pelvic and lumbar lymphatic glands ; some accompany the ovarian veins. 
 
 The nerves, as seen in the pregnant condition, have been well described and figured by 
 Tiedemann. Some of them are derived from the renal plexus, and surround the ovarian 
 arteries ; others proceed from the hypogastric plexus, and are formed by some of the 
 anterior branches of the sacral nerves, and by branches from the lumbar ganglia of the 
 sympathetic. 
 
 Development. — It is generally agreed that the body of the uterus is always bifid, or two- 
 horned, in the embryo, up to the end of the third month ; and that, towards the end of 
 the fourth month, the two halves are united to form a single cavity. I have not observed 
 tliis in the earliest periods of intra-uterine life. 
 
 During fcetal life, the uterus, instead of presenting the same form as it subsequently 
 possesses, is decidedly larger at the neck than in the body : at this period the broadest 
 part of the uterus is its vaginal extremity. 
 
 After birth, and up to the time of puberty, the development of the uterus is almost 
 stationary ; so that, according to the observations of Roederer, which are confirmed by 
 Professor Duges, it is from twelve to fourteen lines long in the new-born infant, and only 
 an inch and a half at ten years of age. 
 
 At puberty, the uterus rapidly acquires its full dimensions, and at the same time be- 
 comes the seat of a periodic and sanguineous exhalation, the occurrence of which con- 
 stitutes menstruation. 
 
 In old age, the uterus becomes atrophied, and altered in shape ; the cervix and body 
 are separated by a much more decided constriction. These two parts of the uterus 
 seem to become more independent of each other. The lips of the os tincae are general- 
 ly effaced in old women. The tissue of the body preserves its softness, while that of 
 the neck acquires an extreme density. 
 
 The situation of the uterus is very different at different ages. In the foetus it projects 
 beyond the brim of the pelvis, and is in the abdominal cavity ; after birth, and in conse.- 
 quence of the development of the pelvis, it seems gradually to sink into that cavity. At 
 the age of ten years, the fundus of the uterus is on a level with the brim ; afterward it 
 is lower down. In old women it is generally inclined to one side, or reversed upon the, 
 rectum. 
 
 Functions. — The uterus is the organ of gestation ; the fecundated ovum is deposited 
 in its cavity, and there meets with the most favourable conditions for its development. 
 The uterus is also the principal agent in the expulsion of the foetus. 
 
 The Vagina. 
 
 The vagina is a membranous canal, extending from the vulva to the uterus ; it is the 
 female organ of copulation, and also forms the passage for the menstrual blood, and the 
 product of conception. 
 
 It is situated in the cavity of the pelvis between the bladder and the rectum, and is 
 held in that situation by tolerably close adhesions to the neighbouring parts, but still is 
 so loose that it can be everted like the finger of a glove. 
 
 Direction. — It is directed obliquely forward and downward, i. e., it coincides with the 
 axis of the outlet of the pelvis ; and as the direction of the uterus corresponds with the 
 axis of the brim, these two parts form an angle or curvature with each other, having its 
 concavity directed forward. 
 
 Shape and Dimensions. — The vagina is shaped like a cylinder, flattened from before 
 backward, and having its walls in contact, as may be seen upon applying the speculum. 
 It is from four to five inches long ;* sometimes it is much shorter : I have seen it as 
 short as an inch and a half This congenital shortness must be distinguished from the 
 apparent shortness produced by prolapsus uteri. 
 
 The vagina is not of the same diameter throughout. Its lower orifice is the narrow- 
 est part, while its upper extremity is the widest. In females who have borne children, 
 the bottom of the vagina forms a large ampulla, in which the speculum may be moved 
 about extensively, and in Avhich, also, a considerable quantity of blood may accumulate 
 during hemorrhage. It is, moreover, a dilatable canal, as is proved during parturition ; 
 and is, at the same time, elastic, and contracts after delivery, so as almost to return to 
 its original dimensions. It would appear, also, to be capable of a vermicular contraction. 
 
 Relations. — In front, where it is slightly concave, it corresponds to the inferior fundus 
 of the bladder, to which it is united by very dense filamentous cellular tissue, resembling 
 the dartos ; it cannot be separated from the urethra, which appears to be hollowed out 
 of the substance of its walls. The close adhesion of the vagina to the bladder and ure- 
 tlua accounts for these latter organs always following the uterus in its displacements. 
 Behind, the vagina corresponds with the rectum, through the medium of the peritoneum 
 in its upper fourth, and immediately in its lower three fourths. It adheres to the rec- 
 
 * LFrom the nature of the cune formed by the vagina, its anterior wall is shorter than the posterior.] 
 
THE VAGINA. 4^ 
 
 turn by cellular tissue resembling the dartos, and analogous to that existing between it 
 and the bladder, but much looser, so that the rectum does not follow the vagina in its 
 displacement. The sides of the vagina give attachment to the broad ligaments above, 
 and to the superior pelvic fascia and the levatores ani below, and they are in relation 
 with the cellular tissue of the pelvis and with some venous plexuses. 
 
 Internal Surface. — The internal surface of the vagina is covered with an epithelium, 
 which can be very easily demonstrated, and which is prolonged as far as the os uteri, 
 where it terminates by a sort of indented margin, in the same manner as the epithelium 
 of the oesophagus ceases at the stomach.* This surface presents on both walls, but es- 
 pecially in front and near the orifice of the vulva, some transverse rugae, or, rather, 
 prominences, which very nearly resemble the irregular ridges upon the palate ; they all 
 pass from a median prominent line, which is often prolonged like a median raphd along 
 the whole anterior wall of the vagina ; the raphe on the posterior wall is not so well 
 marked. These two median raphes are called the columns of the vagina. They are 
 the remains of the median septum, which generally coexists with a bifid uterus, but ex- 
 ists sometimes independently of it. 
 
 The transverse rugae of the vagina are very numerous in the new-bora infant and in 
 virgins ; they are partially effaced after the first labour, at the upper part of the vagina, 
 but always remain at the lower part. These rugae are not folds, and do not appear to 
 assist in the enlargement of the vagina. 
 
 The upper extremity of the vagina embraces the neck of the uterus, upon which it is 
 prolonged without any line of demarcation, and forms a circular trench around the os 
 tincae, which is deeper behind than in front. 
 
 The lower extremity, or opening into the vulva, presents a corrugated transverse pro- 
 jection in front, which is exposed by separating the labia and nymphae ; it narrows, and 
 seems even to close the entrance of the vagina. 
 
 In virgins, the orifice of the vulva is provided with a membrane, concerning the form 
 and existence of which there have been numerous disputes ; it is called the hymen, and 
 is a sort of diaphragm interposed between the internal genitals on the one hand, and the 
 external genitals and urinary passages on the other. This membrane is of a crescentic 
 shape, having its concavity directed forward, and closing up the posterior and lateral 
 parts of the vagina: it sometimes forms a complete circle, perforated in the centre. Its 
 free margin is fringed ; it varies in breadth in different individuals, and thus regulates 
 the dimensions of the vaginal orifice. The hymen sometimes forms a complete mem- 
 brane, constituting what is called imperforate vagina. 
 
 The hymen is composed of a duplicature of mucous membrane, varying in strength, 
 and containing within it some cellular tissue and vessels. The debris remaining after 
 its laceration constitute the carunculce myrtiformes, which vary in number from two to five. 
 
 Structure. — The walls of the vagina consist of an erectile spongy tissue interposed be- 
 tween two very strong fibrous layers, of which the external is the thicker. Around this 
 erectile tissue we find a tolerably thick layer resembling the tissue of the dartos con- 
 densed. I cannot agree with sonie anatomists in admitting an identity of structure in 
 the walls of the vagina and uterus, for in no case does the vagina assume a muscular 
 character hke the latter organ. From the presence of the dartoid tissue an obscure ver- 
 micular movement may take place, and assist the elasticity of the walls of the vagina. 
 
 The posterior wall and the upper part of the anterior wall are thin ; the vagina is veiy 
 much thicker opposite the urethra, which seems to be hollowed out of its substance, and 
 terminates by a rugous enlargement, which forms, at the entrance of the vagina, the pto- 
 jection already mentioned, and which is only a very dense spongy tissue. 
 
 The mucous membrane of the vagina is remarkable for the thickness of its epitheli- 
 um,t for its close adhesion to the proper membrane, and for its highly developed papillae, 
 especially at the entrance of the passage, where the rugae are nothing more than papillae 
 in an exaggerated form. The mucous follicles can be easily demonstrated. 
 
 The Bulb of the Vagina. — Besides the spongy expansion at the orifice of the vagina, 
 there is in front and on each side of this orifice an enlargement or cavernous body, occu- 
 pying the interval between the entrance of the vagina and the roots of the clitoris. It 
 is not very thick in the middle, where it is placed between the meatus urinarius and the 
 union of the roots of the clitoris, but gradually enlarges from this point, and terminates 
 below, upon each side of the vagina, by an enlarged extremity. The posterior wall of 
 the vagina is the only part in which it does not exist. In position, as well as shape, it 
 resembles the bulb of the urethra in the male. J 
 
 The Constrictor Vagina. — ^This consists of two muscles, one on each side of the ori- 
 fice of the vagina, the arrangement of which very nearly resembles that of the bulbo- 
 
 * tin both of these situations the epithelium does not cease, but is merely changed in its character (see 
 note, p. 467).] 
 
 t [The epithelium in the vagina, and also in the vulva, is squamous.] 
 
 t In one subject, on the outer side of this vaginal bulb, I found a smooth sero-fibrous pouch, containing' a 
 transparent mucous fluid. A narrow canal, proceeding from this pouch, passed directly towards the entrance 
 of the vagina. I could not find the orifice of this caual, which was probably obliterated. The same dispoai- 
 tion existed on both sides. 
 
470 SPLANCHNOLOGY. 
 
 cavernosus in the male. Each muscle commences in front of the rectum, by an inter- 
 lacement of fibres common to it, to its fellow of the opposite side, and to the sphincter 
 ani, passes forward under the fonxi of a flattened band, and terminates upon the sides 
 of the clitoris, a portion being continued above it, and blended with the suspensory liga- 
 ment of that body. 
 
 Relations. — It is covered on the outside by the skin and the fatty cellular tissue of the 
 labia majora ; it corresponds on the inside with the bulb of the vagina, which it must 
 strongly compress. 
 
 The proper vaginal arteries arise from the hypogastric. The uterine arteries also 
 send numerous branches to the vagina. 
 
 The veiiis are very niunerous, form plexuses, and terminate in the hypogastric veins. 
 
 The turves are derived from the hypogastric plexus. 
 
 Development. — The rugae of the vagina are not visible until about the end of the fifth 
 month of intra-uterine life ; from the sixth to the eighth they become much more devel- 
 oped than they are subsequently. The transverse rugae are visible in the whole length 
 of the vagina, and are placed closely to each other. The hymen does not make its ap- 
 pearance until about the middle of fcetal life ; it is directed forward, and is rough and 
 jagged. It is always present. 
 
 The Urethra in. the Female. 
 
 This canal, which is, as it were, hollowed out of the anterior wall of the vagina, dif- 
 fers considerably from the male urethra, of which it represents the membranous portion 
 only. It is about one inch in length. 
 
 It is very difficult to determine its diameter, on account of its dilatability ; but it is 
 about three or four lines when quite undilated. Its lower end is somewhat contracted. 
 
 It is directed obliquely downward and forward, and is slightly concave in front. 
 
 Relations. — Anteriorly, while behind the symphysis, it is in contact with the cellular' 
 tissue of the pelvis ; opposite the symphysis, it is in relation with the angle of union of 
 the two crura of the clitoris. The pelvic fascia, or, rather, the anterior ligaments of the 
 bladder, form a half sheath for it above, but are separated from it by numerous venous 
 plexuses. Posteriorly, the canal is so closely united to the vagina, that it is impossible 
 to separate them. 
 
 The vesical orifice of the female urethra is similar to that of the male, only there is no 
 prostate gland. 
 
 The internal surface is of a deep colour, and is remarkable for certain longitudinal folds 
 or parallel ridges, the majority of which are not effaced by distension ; one of these folds 
 is in the median line of the lower wall of the canal. We also find the orifices of mucous 
 crypts or lacunae, and some parallel longitudinal veins. 
 
 Structure. — It is muscular and erectile, like the membranous portion of the male ure- 
 thra. It is surrounded by a thick layer of circular muscular fibres, which seem to be 
 continuous with the fibres of the bladder, some of the longitudinal fibres of that organ 
 being prolonged upon the outside of these.* A thin layer of spongy or erectile tissue lies 
 subjacent to the mucous membrane, which is very thin. 
 
 The Vulva. 
 
 Under the term vulva we include all the external genitals of the female, viz., the mons 
 Veneris, the labia majora and minora, the clitoris, and the meatus urinarius, to which 
 we may add the orifice of the vagina already described. 
 
 The mons Veneris is a rounded eminence, more or less prominent in different individ- 
 uals, situated in front of the pubes, and surmounting the vulva ; the prominence of this 
 part is owing partly to the bones, and partly to a collection of fatty tissue beneath the 
 skin ; it is covered with hair at the time of puberty. 
 
 The labia majora are two prominent cutaneous folds, which form the limits of an an- 
 tero-posterior opening, by most anatomists named the vulva. They are flattened trans- 
 versely, and are thicker in front than behind ; their external surfaces are covered with 
 hairs ; their internal surfaces are moist and smooth, and in contact with each other ; 
 their free borders are convex, and provided with hair ; their anterior extremities are con- 
 tinuous with the mons Veneris ; their posterior extremities unite to form a commissure 
 called the fourchette, which is almost always lacerated in the first labour. The interval 
 between the fourchette and the anus constitutes the perineum, which is generally from 
 
 * [The female urethra perforates the triangular ligament precisely in the same way as the membranous por- 
 tion of the urethra in the male ; and, moreover, between the two layers of the ligament it is surrounded by mus- 
 cular fibres corresponding exactly with the compressor urethra in the male sex. The vertical fibres, or Wil- 
 son's muscles, were noticed by him (loc. cit.), descending from the symphysis, separating on the urethra, and 
 passing around it ; the transverse fasciculi, which are often very large, form together the depressor urethra Of 
 Santorini, and were described and figured by that author (Obs. Anat.) as arising by a broad tendou from the 
 lower part of the rami of the pubes, above the erectores clitoridis, passing obliquely upward and inward, and 
 uniting with each other dijove the urethra. Mr. Guthrie has shown {loc. cit.) that the relations of the verti- 
 cal and transverse fasciculi to each other, to the urethra, and to the layers of the Uiaugular ligament, are pre- 
 cisely the same as in the male.] ' .,-j4J-i 
 
THE VULVA. 471 
 
 eight to ten lines long. The interval between the fonrchette and the entrance of the 
 vagina is called the fossa navicularis. 
 
 The constituent parts of the labia majora are, a cutaneous layer, a mucous layer, both 
 provided with numerous sebaceous follicles.* In fat persons, a great quantity of adipose 
 tissue, a layer of dartoid tissue next the mucous membrane, and some arteries, veins, 
 lymphatics, and nerves. They are therefore very analogous to the scrotum in the male, 
 and, Uke it, are liable to serous infiltration in anasarca. 
 
 The labia minora, or nymphcB, are seen after separating the labia majora, under the 
 form of two layers of mucous membrane ; they are narrow behind, where they commence 
 upon the inner surface of the labia majora, and they enlarge gradually as they converge 
 towards each other in front. At the chtoris they become slightly contracted, and bifur- 
 cate before their termination. The lower division of the bifiircation is attached to and 
 continuous with the glans of the clitoris ; the upper division unites with that of the op- 
 posite side, and forms a hood-like fold above that body, called the preputium clitoridis. 
 
 Tlie nymphae are provided with very large crypts, wliich are visible to the naked eye, 
 and secrete an abundance of sebaceous matter. They vary much in size, according to 
 age : thus, in new-bom infants, they project beyond the labia majora, principally on ac- 
 count of the imperfect development of the latter. They also vary in different individ- 
 ujds : in some females being extremely small, and in others always projecting beyond 
 the labia majora ; and, lastly, in different countries ; for in certain African nations, among 
 the Hottentots, for example, they are of a disproportionate length, and constitute what 
 is called in females of that race the apron. 
 
 The clitoris is an erectile apparatus, forming a miniature representation of the corpus 
 cavernosum of the penis. Its free extremity is seen in the anterior part of the vulva, 
 about six lines behind the anterior commissure of the labia majora, and resembles a tu- 
 bercle situated in the median line, covered, as by a hood, with the upper divisions of the 
 bifurcated nymphae, and continuous with the lower divisions of the same. This tuber- 
 cle, which, though imperforate, has been compared to the glans penis {glans clitoridis), is 
 generally very small. Sometimes, however, it is very long, so as to have excited a sus- 
 picion of the existence of hermaphrodism. In one instance that came under my obser- 
 vation, the free part of the clitoris was two inches long, and extremely slender. 
 
 Like the corpus cavernosum in the male, the clitoris arises from the ascending rami 
 of the ischia by two roots, which expand and converge until they arrive opposite the 
 symphysis, where they unite and form a single corpus cavernosum, flattened on each 
 side ; this, after passing for some lines in front of the symphysis, separates from it, and 
 forming a curve with the convexity directed forward and upward, and the concavity 
 downward and backward, gradually becomes smaller towards its free extremity. 
 
 It has a suspensory ligament precisely resembling that of the penis, and ischio-cavei- 
 nosi muscles, similar to, but smaller than those of the male. We have already said that 
 the constrictor vaginae, which represents the bulbo-cavemosi of the penis, has a similar 
 arrangement to those muscles, t. c, it passes upon the sides of the clitoris, and then be- 
 comes continued on to its suspensory ligament. 
 
 The last circumstance which completes the analogy between the clitoris and the corpus 
 cavernosum of the penis, is the reception of the canal of the urethra into the V-shaped 
 interval formed by the union of the two crura of the clitoris. 
 
 The corpus cavernosum of the clitoris forms a longitudinal ridge between the labia ma- 
 jora, extending from the anterior commissure to the glans of the clitoris. 
 
 The Meatus Urinarius. — About an inch below and behind the clitoris, we find in the 
 median line, immediately above the projecting margin of the opening of the vagina, tfce 
 meatus urinarius, or the orifice of the urethra, which constantly appears closed. 
 
 The Mucous Membrane of the Vulva. — The mucous membrane lining the vulva is con- 
 tinuous, on the one hand, with the skin at the intemad surface of the labia majora, and 
 with the mucous membrane of the vagina on the other ; upon the labia majora and nym- 
 phae it has a great number of sebaceous follicles visible to the naked eye, and yielding a 
 cheesy, odorous secretion ; and also mucous follicles, which are most numerous near the 
 meatus urinarius, and open into culs-de-sac, the orifices of which are visible to the na- 
 ked eye, and are often large enough to admit the blunt extremity of a probe. 
 
 Development. — In the foetus the labia majora are small, and separated from each other 
 by the nymphae, which are much larger in proportion, and also by the clitoris, which pro- 
 jects beyond them to a greater extent in the earlier periods of development. This pre- 
 dominance of the clitoris is still so decided at birth, that it has occasioned mistakes con- 
 cerning the sex of the infant. 
 
 THE MAMM^. 
 Number. — Situation. — Size. — Form. — Structure. — Development. 
 The mavima or breasts (jiadrbg, from fidu, to seek eagerly, because the infant seeks^ 
 
 * It is not rare to see small and very short hairs growing from the sebaceous follicles on the inner surface 
 of the labia majora ; they are analogous to '.hose of the carunculse lachrymales. 
 
472 SPLANCHNOLOGY. 
 
 them for the milk) are glandular appendages of the generative system, which secrete 
 the milk, and even after birth establish intimate relations betvireen the mother and the 
 infant. 
 
 The important office performed by the mammje has led zoologists to arrange in the 
 same class, under the term mammalia, all animals having an apparatus for lactation. We 
 may mention here another character peculiar to this class of animals, because it is in- 
 timately connected with the existence of mammae, viz., that all mammalia are vivip- 
 arous that is to say, give birth to their young freed from all their foetal envelopes. 
 
 The mammsE exist in both sexes, but are rudimentary and atrophied in the male, and 
 belong essentially to the female. 
 
 Number. — They are two in number in the human species, which is uniparous ; in the 
 lower animals they are generally double the number of the young. Examples of three 
 or four mammae in the human subject are very rare, and the supernumerary mammae 
 are generally nothing more than simple nipples, or, rather, masses of fat. 
 
 Situation. — They are situated on the anterior and upper part of the chest, the trans- 
 verse enlargement of which in the human subject is so favourable to their development. 
 In the lower animals they occupy the abdominal region. 
 
 They are situated on each side of the median line, over the interval between the third 
 and the seventh ribs. They are therefore placed at the same height as the arms, and 
 occupy this region, says Plutarch, in order that the mother may be able to embrace and 
 support her infant while she is suckling it. 
 
 Size. — In the male they are rudimentary during the whole of life ; in the female until 
 the period of puberty only, when they become much enlarged as the generative appara- 
 tus is developed more completely. They again increase in size during pregnancy, and 
 especially after delivery ; they become atrophied in old age. In some females who are 
 still young, the size of the mammas by no means corresponds to their statm-e, strength, 
 and soundness of constitution ; while, on the other hand, it is not uncommon to see thin, 
 phthisical individuals with very large breasts. In judging of the size of the mammae, we 
 must not confound that depending upon the gland itself with that due to fat. The lar- 
 gest breasts are not always those which furnish the most milk, because their extreme 
 size often depends on an accumulation of fat, the gland itself being small. The left mam- 
 ma is almost always a little larger than the right. 
 
 Form. — The mammae represent a semi-sphere surmounted by a large papilla called the 
 nipple. 
 
 The skin covering the mamma is remarkably delicate. Surrounding the nipple is an 
 areola or aureola of a pinkish hue in young girls, but of a brownish colour in most females 
 who have borne children ; it has also a rough appearance, owing to a number of sebace- 
 ous glands, which yield a kind of waxy secretion that prevents the irritating action of 
 the saliva of the infant. Morgagni, Winslow, and Meckel state that they have observed 
 milk to escape from them ; but if there was no error in their observations, it must be 
 admitted that, by some unusual anomaly, a lactiferous duct opened at the side of one of 
 these little glands. 
 
 The mammilla or nipple is of a pinkish or brown colour, rough, and, as it were, crack- 
 ed at the summit, and capable of undergoing a sort of erection ; it varies in form and 
 size in different subjects ; it is either cylindrical or conical, and sometimes so short that 
 the lips of the infant cannot lay hold of it ; in certain cases it is even depressed. In the 
 centre of the nipple we observe one or more depressions, in which the lactiferous ducts 
 open by a variable number of orifices. 
 
 The papilla is provided also with a great number of sebaceous glands having the ap- 
 pearance of tubercles, and secreting a substance which prevents the nipple from being 
 chapped by the act of sucking and the saliva of the infant.* 
 
 Structure. — The breasts consist of the mammary glandular tissue and of fat. 
 
 The Mammary Gland. — ^When freed from the fat by which it is surrounded, the mam- 
 mary gland appears like a mass flattened from before backward, and thicker in the cen- 
 tre than at its circumference, which is irregular, but less so on the inside than on the 
 outside. Its base, which is plane, and even slightly concave, rests upon the pectoralis 
 major, and sometimes beyond it upon the serratus magnus ; a continuation of the fascia 
 superficialis separates it from these muscles, to which it adheres by very loose serous 
 cellular tissue only, and hence it is very movable. 
 
 The cutaneous surface of the mammary gland is very unequal, and forms alveoli filled 
 by fat, by which means the inequalities are concealed. 
 
 The proper tissue of the gland is considerably denser than that of most glandular or- 
 gans. It should be examined both during lactation, and when that function is not being 
 performed. 
 
 In the absence of lactation, the gland has the appearance of a very compact, whitish, 
 
 * [Sir A. Cooper has described numerous cutaneous papillae upon the nipple and areola ; they are highly 
 *wascular and nervous. He has also shown that the glands found in the areola and at the base of the nipple 
 nave branched ducts, ending in blind extremities : in the female, from one to five open on each tubercle.— 
 (Anatomy of the Breast, 1840.)] 
 
THE MAMMiE. 473 
 
 fibrous tissue, divided into unequal lobes, which cannot be compared to anything bettei 
 than to certain fibrous tumours of the uterus. The granular structure proper to the tis- 
 sue of glands is not visible during this state. 
 
 During lactation, the granular structure becomes very evident. The following are 
 the results of my observations respecting it at this period : The glandular granules or 
 lobules are united into small clusters, forming flattened lobes, placed one upon another. 
 From each little lobe proceeds an excretory duct, which may be recognised by its white 
 colour, is easily injected, and is formed by the union of a number of smaller ducts cor- 
 responding to the number of lobules. Having had an opportunity of dissecting the mam- 
 ma of a female recently delivered, in which the cellular tissue between the lobules was 
 infiltrated with serum, the lobules themselves, as it were, dissected, and the lactiferous 
 ducts injected with yellowish coagulated milk, I found that some of the lobules were iso- 
 lated, and, as it were, pediculated, while others were collected into regular or irregular 
 clusters. In one of these clusters the lobules had a circular arrangement, small ducts 
 proceeded from each lobule, and, passing from the circumference towards the centre of 
 the circle like radii, opened into a common efferent duct, which issued from the central 
 point. Another cluster was elongated and swollen at intervals, and in the centre was 
 a duct which received the smaller ducts from the several lobules. Each lobule had a 
 central cavity, from which a worm-shaped mass of coagulated caseous matter could be 
 expressed. When examined by the simple microscope, the parietes of these cavities 
 had a spongy aspect like the pith of the rush, a character which I have already noticed 
 as belonging to all glandular organs.* 
 
 The Fibrous Tissue of the Mamma. — Besides the lobules, a large quantity of fibrous tis- 
 sue also enters into the structure of the gland, forms a complete investment for it, and 
 then sends more or less loose prolongations into its substance, and unites the lobes to- 
 gether. It is to the great quantity of fibrous tissue that the hardness of the mammary 
 gland is to be ascribed. Sometimes the enlargement of the mamma at the time of pu- 
 berty is confined entirely to the fibrous tissue ; in such a case, the organ may acquire an 
 enormous size, the glandular tissue disappears, and the mamma is transformed into a 
 many-lobed fibrous mass, wliich has been sometimes mistaken for a degenerated lipoma. 
 The Adipose Tissue. — The alveoli on the outer surface of the mamma are filled with 
 masses of fatty tissue, which are separated by fibrous laminae extending from the gland 
 to the skin. The cells in which these masses are contained do not communicate with 
 each other, and hence the frequency of circumscribed abscesses in the mamma. The 
 relative quantities of fat and glandular tissue have an inverse ratio to each other. The 
 great size of the mammae in some men is owing to development of the fatty tissue. 
 Haller says that it is an essential element in the structure of the gland, and that he has 
 several times seen lactiferous ducts arise from it. 
 
 The Lactiferous Ducts. — If the mamma of a female who has died during lactation be 
 divided, the milk will be seen to exude from a number of points, as from the pores of a 
 sponge ; these points correspond to sections of the thin, whitish, semi-transparent ex- 
 cretory ducts of the mammary glands, which are called lactiferous, or galactophorous ducts. 
 They arise from the lobules, and perhaps, also, from the fatty tissue, as was thought by 
 Haller ;t they unite successively like the veins, converge from the circumference to the 
 centre, traverse the substance of the gland, and at length form a variable number of 
 ducts, which reach the centre of the gland, opposite the areola. In that situatioa they 
 acquire their utmost size, and form considerable ampullae or dilatations, between which 
 scarcely any intervals are left. According to some anatomists, the number of these am- 
 pullae is not less than twenty ; I have never counted more than ten. They are of un- 
 equal size. At the base of the nipple they become contracted, straight, and parallel, and 
 open upon its summit by orifices, which are much narrower than the ducts themselves. 
 Thus, then, although there is no reservoir properly so called in the mammary gland, the 
 ampullae above described may be regarded as such ; with this difference only, that in- 
 stead of one reservoir there are several. 
 
 The lactiferous ducts, moreover, are surrounded, both in the mammilla and opposite 
 the areola, with a dartoid tissue, the existence of which explains the state of orgasm 
 and erection of the nipple, as well as the expulsion of the milk in a jet when the gland 
 is excited. There is no trace of the cavernous structure described by some anatomists 
 as existing in the nipple. The lactiferous ducts do not communicate with each other in 
 any part of their course ; neither in their terminating canals, nor in their ampullae, nor 
 in their smaller ducts ; this may be proved by mercurial injections, or by filling each 
 duct with a differently-coloured injection. The mammary gland, like most others, is 
 therefore divided into a certain number of distinct compartments, which may perform 
 their functions independently of each other. 
 
 Injections also show that the lactiferous ducts have no valves. Tlieir structure is little 
 
 * tThe ultimate structure of the mammary gland consists of the terminations of the lactiferous ducts in 
 clusters of microscopic cells within each lobule ; these cells are round, and have a diameter twenty times as 
 great as that of the capillaries which ramify upon them. 
 
 + (Our present knowledge of the minute structure of glands has proved the inaccuracy of this supposition ol 
 HaUerJ 
 
 o 
 
474 
 
 SPLANCHNOLOGY. 
 
 known. It is generally admitted that they consist of an internal membrane continuoQs 
 with the skin, and which must be analogous to the mucous membranes, and of an exter- 
 nal fibrous coat, which I am inclined to regard as analogous to the tissue of the dartos. 
 
 The arteries of the manuna arise from the thoracic, especially that which is called the 
 external mammary, also from the intercostals and the internal mammary. 
 
 The veins are very large, and of two kinds, sub-cutaneous and deep ; the latter accom- 
 pany the arteries, the former are visible through the skin. 
 
 The lymphatics are very numerous, and enter the axillary glands. The older anato- 
 mists admitted a direct communication between the thoracic duct and the glandular tis- 
 sue of the breast ; but this opinion, suggested by the resemblance in colour between the 
 chyle and milk, is altogether erroneous. 
 
 The nerves are derived from the intercostals and the thoracic branches of the brachial 
 plexus. 
 
 Development. — The mammae become visible after the third month of intra-uterine life. 
 At birth they are more developed than at a subsequent period, and contain a certain 
 quantity of miUcy viscid fluid. Until puberty the mammae of the two sexes differ only in 
 the nipple being larger, and the gland somewhat larger in the female than in the male. 
 
 In the female, at puberty, they gradually acquire the size which they subsequently re- 
 tain, their development coinciding with that of the genital organs. Most commonly the 
 change precedes, but sometimes it follows, the appearance of the menses. 
 
 The mammae of the male also participate in the development of the generative appara- 
 tus at the time of puberty, and in some subjects even a milky secretion is formed.* 
 
 The manunae become atrophied in old age, and are sometimes replaced by fibrous tis 
 sue ; in several old women I have found the lactiferous ducts distended with a dark, in- 
 spissated mucus, of a gelatinous consistence which has enabled me to trace the ducts 
 even to their most delicate radicles. 
 
 THE PERITONEUM. 
 
 The Suh-umhilical Portion. — The Supra-umbilical Portion. — General Description and 
 
 Structure. 
 The peritoneum (nepl, around, and teIvu, to extend) is a serous membrane, which, on 
 the one hand, lines the abdominal parietes, and, on the other, invests nearly all the vis- 
 cera contained in the cavity of the abdomen. 
 As it enters into the formation of almost all the abdominal viscera, it has been already 
 Fig, 190. partially examined while describing them. It remains 
 
 for us to demonstrate these parts as a whole, and for 
 this purpose, we shall suppose the membrane to com- 
 mence at one particular point, and shall trace it with- 
 out interruption in a circular course until we again ar- 
 rive at the point from which we started. 
 
 The peritoneum is the largest and most complica- 
 ted of the serous membranes ; it forms, like all of 
 them, a shut sac, the external surface of which ad- 
 heres to the parts over which it is reflected, while its 
 internal surface is free and smooth. 
 
 Taking the umbilical region as a point of departure, 
 we shall divide the peritoneum into two portions, a 
 superior, epigastric or supra-umbilical, and an inferior 
 or sub-umbilical portion. 
 
 The Inferior or Sub-umbilical Portion of the Peritone- 
 um.. — The inferior or sub-umbilical portion, supposed 
 to commence at the umbilicus, lines the whole of the 
 parietes of the abdomen (a, ^^. 190) below that point. 
 In so doing, it is raised up by the urachus and the two 
 umbilical arteries, or, rather, by the ligaments repla- 
 cing those arteries, so as to form three falciform folds, 
 one median and two lateral, which converge towards 
 their termination at the umbilicus, but diverge in the 
 direction of the bladder ; the peritoneum then dips 
 into the pelvis, and covers the fundus, the sides, and 
 the posterior surface of the bladder (J), but to a varia- 
 ble extent, according as that organ is distended oi 
 empty. When the bladder is contracted, the perito- 
 neum descends behind the symphysis ; when, on the 
 
 * [It has been shown by Sir A. Cooper, that the mammary gland 
 of the male has a system of ducts and cells like those of the fejnals 
 gland, but very much smaller.] 
 
THE PERITONEUM. 475 
 
 Other hand, it is distended and rises into the abdomen, the peritoneum retires before ii, 
 and the bladder then comes into direct contact with the anterior wall of the abdomen, 
 so that it can be reached by the surgeon without wounding the peritoneum. 
 
 From the posterior surface of the bladder the peritoneum is reflected upon the other 
 pelvic organs, being arranged differently in the two sexes. In the male it is reflected 
 from the bladder upon the rectum, forming- two lateral semilunar folds, called the pos- 
 terior ligaments of the bladder, and a cul-de-sac between them of variable depth, which 
 sometimes reaches as low as the prostate.* In the female it is reflected from the pos- 
 terior surface of the bladder upon the neck of the uterus (m), forming a cul-do-sac between 
 the two, so that the inferior fundus of the bladder is entirely uncovered by it. It then 
 covers the two surfaces and the superior border of the uterus, and forms two lateral, 
 broad, transverse folds (the ligamenta lata), each of which is subdivided superiorly into 
 three smaller folds, the ala vespertilionis or ala of the broad ligament, the anterior fold 
 corresponding with the round ligament, the middle one to the Fallopian tube, and the 
 posterior fold to the ovary. 
 
 The peritoneum has no relation with the front of the vagina (b), but it covers the up- 
 per third of that canal behind ; from thence it is reflected upon the rectum (r), and has 
 then the same arrangement in both sexes. Inferiorly it is limited to the anterior sur- 
 face of the gut, but superiorly it entirely surrounds it, excepting behind, where it forms 
 a duplicature known as the mesorectum. 
 
 After leaving the cavity of the pelvis, the peritoneum continues to ascend, so as to 
 cover the posterior wall of the abdomen ; in this situation we shall examine it in the 
 middle and at the sides. 
 
 In the middle it passes in front of the sacro- vertebral angle, then in front of the lumbar 
 vertebrae, and having arrived opposite an oblique line, extending from the left side of the 
 second lumbar vertebra to the right iliac fossa, it is reflected forward to constitute the 
 left layer (m) of the mesentery {neaoq, middle, evrepov, an intestine) ; it immediately ex- 
 pands, so as to correspond to the whole length of the small intestine (i), lines the left 
 lateral half, the convex borders, and the right lateral half of that intestine, and then pass- 
 ing from before backward (m'), is applied to the back of the layer just described, and in 
 this manner forms the mesentery (m m'), the largest of all the duplicatures of the peri- 
 toneum, and remarkable for its resemblance to a plaited ruffle. 
 
 On the left side, the peritoneum, after having formed the mesorectum, then forms the 
 iliac Tnesocolon, a considerable fold, which allows great mobility to the sigmoid flexure of 
 the colon. From the sigmoid flexure it is prolonged upon the left lumbar colon, cover- 
 ing the anterior five sixths of that part of the intestine, and applying it against the kidney, 
 but without forming any duplicature for it ; so that the kidney and the colon are in im- 
 mediate relation. Still, the left lumbar colon is not unfrequently entirely surrounded by 
 the peritoneum, so as to have a duplicature behind it, called the left lunibar mesocolon. 
 
 Along the whole course of the great intestine, the peritoneum usually forms a number 
 of small folds containing fat, and named the appendices epiploica. 
 
 On the right side the peritoneum arrives at the caecum, and may be arranged in one of 
 two modes : it either entirely invests that portion of intestine, which is then very mo- 
 vable ; or else, and this is the most common arrangement, it passes iimnediately in front 
 of the cascum, which is thus applied against the right iliac fossa, and is attached there 
 by rather loose cellular tissue. The peritoneum sometimes forms a small mesentery 
 for the vermiform appendix, sometimes fixes it against the posterior surface of the 
 caecum, or against the ileum, or, lastly, against the lower portion of the mesentery. Above 
 the caecum the peritoneum covers the right lumbar colon, and has the same arrange- 
 ments as on the left side. 
 
 Such is the course of the sub-umbilical portion of the peritoneum. 
 
 The Superior or Supra-umblical Portion of the Peritoneum. — We shall trace the superior 
 or supra-umbilical portion from the umbilicus to the posterior wall of the abdomen, op- 
 posite to the mesentery and the lumbar mesocolon, to which points we have already 
 traced the lower portion. 
 
 Commencing at the umbilicus and proceeding upward, the peritoneum (e) lines the an- 
 terior abdominal parietes ; on the right side it meets with the umbilical vein, or the 
 fibrous cord to which that vein is reduced in the adult, covers it, and forms a falciform 
 duplicature, named the suspensory ligament of the liver, or falx of the umbilical vein ; this 
 fold is of a triangular shape, its apex corresponds with the umbdicus, and its base with 
 the upper surface of the liver, which is divided by it into two lateral portions or lobes, t 
 From the umbilicus, then, as from a centre, proceed four peritoneal folds : one superior 
 or ascending, for the umbilical vein ; and three descending, one for the urachus and two 
 for the umbilical arteries. 
 
 From the anterior wall of the abdomen, the peritoneum is continued upon the Idwer 
 
 * The peritoneum, forming the cul-de-sac between tlie bladder and the rectum, sometime.s has a fissured ap- 
 pearance, like that seen upon the parietes of the abdomen in women who have had many children. 
 
 t [Its lower free margin encloses the umbilical vein, and its upper or interior border is attached to the ab- 
 dominal parietes.] 
 
476 SPLANCHNOLOGY. 
 
 surface of the diaphragm (/), and is arranged differently on the right and left sides and 
 in the middle. 
 
 The Right or Splenic Portion. — The peritoneum, after having lined the lower surface 
 of the diaphragm as far as the vertebral column, is reflected upon the posterior surface 
 of the vascular pedicle of the spleen, covers the posterior half of the internal surface of 
 that organ, its posterior border, the whole of its external surface, the anterior half of 
 its internal surface, and the anterior surface of its vascular pedicle, from which it is pro- 
 longed upon the great end of the stomach, and becomes continuous with the anterior 
 layer of the great omentum. The two layers which are applied to each other, one in 
 front of and the other behind the vessels of the spleen, constitute the gastro-splenic omen- 
 tum. Below the spleen, the peritoneum forms a horizontal fold, or septum, by which 
 that organ is separated from the viscera below it. 
 
 The Middle or Gastro-epiploic Portion. — In the middle the peritoneum lines the lower 
 surface of the diaphragm, as far back as the cardiac extremity of the oesophagus, is re- 
 flected over the anterior surface of the stomach (s), and descends into the abdomen in 
 front of the arch of the colon and the convolutions of the small intestine, to form the an- 
 terior layer (w) of the great omentum. 
 
 After descending towards the lower part of the abdomen for a distance, which varies 
 in different individuals and at different ages, it is folded backward upon itself, and passes 
 upward to form the posterior layer (o) of the great omentum. Having arrived at the con- 
 vex border of the arch of the colon (c), it covers the lower surface of that intestine, and 
 passes horizontally backward (q) to the anterior surface of the vertebral column, in front 
 of which it is again reflected, and becomes continuous with the right layer {m') of the 
 mesentery. The horizontal portion, which extends from the arch of the colon to the 
 vertebral column, forms the inferior layer {q) of the transverse mesocolon. 
 
 It follows, then, that the portion of the peritoneum which is continuous with that upon 
 the anterior surface of the stomach, forms below that organ a kind of bag, which has a 
 direct or descending layer, and a reflected or ascending layer, in the interval between 
 which are placed the stomach (s), the pancreas (p), the duodenum (d), and the arch of 
 the colon (e). We shall afterward find that each of these layers is lined internally by 
 another layer of peritoneum, so that the great omentum consists of four layers of serous 
 membrane. 
 
 The Right or Hepatic Portion. — On the right side the peritoneum is reflected from the 
 diaphragm upon the convex surface of the liver (/), and forms the coronary ligament of 
 the liver (at g), being continuous with the suspensory ligament, the direction of which 
 is at right angles to its ovm. 
 
 From the convex surface of the liver, the peritoneum is reflected over its anterior 
 margin, and then upon its concave surface, investing the gall-bladder, sometimes almost 
 entirely, but generally on its lower surface only. At the transverse fissure it is reflect- 
 ed downward in front of the vessels of the liver, and to the left of those vessels reaches 
 the lesser curvature of the stomach, and is continued upon the anterior surface of that 
 organ. That portion of the peritoneum which extends from the transverse fissure to 
 the lesser curvature of the stomach, constitutes the anterior layer (A) of the gastro-hcpatic 
 or lesser omentum. To the right of the vessels of the liver and to the right of the gall- 
 bladder, the peritoneum covers the lower surface of this viscus, and becomes directly 
 continuous with the portion which covers the right lumbar colon. 
 
 As the peritoneum is reflected from the diaphragm upon the right and left extremities 
 of the liver, it forms two folds, one on each side, called the triangular ligaments of the 
 liver. 
 
 The Foramen of Winslow and Sac of the Omentum. — Behind the vessels of the liver, 
 and under the anterior root of the lobulus Spigelii, is an opening which leads into a cav- 
 ity situated behind the stomach and the gastro-hepatic omentum. This opening is the 
 orifice of the omental sac, or the foramen of Winslow (in which a probe is placed in the 
 figure) ; the cavity is called the posterior cavity of the peritoneum, or the sac of the omen- 
 tum (i). The foramen of Winslow is semicircular, sometimes triangular in shape, and 
 about one inch in its longest diameter. It is bounded in front by the vessels of the liver, 
 behind by the vena cava inferior, below by the duodenum, and above by the neck of the 
 gall-bladder, or, rather, by the lobulus caudatus, or anterior root of the lobulus Spigelii, 
 these several parts being covered with peritoneum. Through this opening the perito- 
 neum enters the sort of pouch formed between the two layers of the great omentum. 
 
 In tracing the course of the reflected portion of the peritoneum, we shall commence 
 at this opening, and shall return without interruption to the same point. The perito- 
 neum is first applied to the posterior surface of the anterior layer of the gastro-hepatic 
 omentum already described, and forms the posterior layer (t) of that omentum ; it then 
 covers the posterior surface of the stomach ; below that organ it is applied (iv) to the 
 descending or anterior layer of the great omentum, behind and parallel to which it passes 
 down ; having arrived at the point where the anterior layer of the great omentum is re- 
 flected, the layer we are now describing is itself reflected (x) in the same manner, and 
 becomes applied to the anterior surface of the posterior layer of that omentum ; con- 
 
THE PERITONEUM. 477 
 
 tinuing to ascend, it gains the convex border of the transverse colon, covers the upper 
 surface of that intestine, and, farther back, is applied to that layer of the great omentum 
 which is continued over the lower surface of the colon ; it thus forms the upper {y) of 
 the two layers of which the traiisverse mesocolon is composed. Having reached the 
 front of the vertebral column, it leaves the inferior layer of the transverse mesocolon, 
 covers the anterior surface of the third portion of the duodenum (d), the anterior surface 
 of the pancreas (f>), the lobulus Spigelii and the anterior part of the vena cava, and ar- 
 rives at the transverse fissure of the liver, opposite the foramen from which we began 
 to trace it. 
 
 It follows, therefore, that the great omentum, notwithstanding its thinness and trans- 
 parency, consists of four perfectly distinct layers, two of which, united together in front, 
 and two behind, constitute the parietes of a cavity called the posterior cavity of the peri- 
 toneum, or the sac of the omentum. 
 
 We may, however, describe the omentum in a different mode, as follows : Two lay- 
 ers of peritoneum applied to each other pass off from the transverse fissure of the liver, 
 separate along the lesser curvature of the stomach, in order to enclose that organ, again 
 unite along its greater curvature, then pass downward, and, opposite the brim of the 
 pelvis, are reflected backward upon themselves, and proceed upward. Having reached 
 the convex border of the colon, they separate to receive that intestine between them, 
 become reunited at its concave border to form the transverse mesocolon, and then sep- 
 arate finally. The inferior layer is reflected downward, to become continuous with the 
 right layer of the mesentery ; the superior is reflected upward, to cover the third portion 
 of the duodenum, the pancreas, and the lobulus Spigelii, and then becomes continuous 
 with the rest of the peritoneum at the foramen of Winslow.* 
 
 General Description of the Peritoneum. — From the preceding description, it follows that 
 the peritoneum forms a continuous membrane, so that, if it were possible to unfold all 
 its duplicatures, and to detach it entire from the surface of all the organs covered by it, 
 it would form a large membranous sac without an opening. Nevertheless, in the fe- 
 male there is a remarkable interruption at the point corresponding to the free extremity 
 of the Fallopian tube, in which situation we find the only example in the body of a serous 
 and mucous membrane being continuous with each other. 
 
 The peritoneum has two surfaces, an external and an internal. The internal surface 
 is free, smooth, and moist, and is the seat of an exhalant and absorbent process, which, 
 in the natural condition, exactly counterbalance one another. 
 
 The external or adherent surface lines the parietes of the abdominal cavity, covers most 
 of the abdominal viscera, of which it forms the external or common coat, and is in con- 
 tact with itself in the different folds formed by the peritoneum. The attachment of this 
 surface is effected by means of cellular tissue, the character of which varies in different 
 situations. 
 
 We shall examine the external surface of the portion of the peritoneum applied to the 
 abdominal parietes, or the parietal peritoneum ; of that upon the viscera, or the visceral 
 peritoneum ; and also of that forming the different folds. 
 
 The Parietal Portion of the Peritoneum. — ^Upon the diaphragm it is attached by a very 
 dense cellular tissue ; nevertheless, it may be torn off in dissecting that part. Upon the 
 anterior wall of the abdomen it adheres most strongly opposite the linea alba and the 
 sheath of the rectus muscle, and more loosely opposite the crural arches than in any 
 other part. Still, it is not very difficult to separate the whole of the membrane correspond- 
 ing to the parietes of the abdomen. In the lumbar region the adhesion is extremely 
 loose, and also in the iliac fossae on the front of the vertebral column : the same is the 
 case in the cavity of the pelvis. 
 
 The cellular tissue on the outside of the peritoneum, which most anatomists have re- 
 garded as forming the external tissue of that membrane, sends prolongations through 
 the numerous openings with which the walls of the abdomen are perforated. These 
 prolongations connect the sub-peritoneal cellular tissue with that of the lower extremi- 
 ties on the one hand, and with the cellular tissue external to the pleura on the other. 
 The peritoneum is supported throughout by a fibrous layer, and this accounts for the dif- 
 ficulty with which abscesses of the abdominal parietes open into the cavity of the peri- 
 toneum. 
 
 The Visceral Portion of the Peritoneum. — Among the viscera of the abdomen some re- 
 ceive a complete investment from the peritoneum, always excepting the point at which 
 their vessels reach them ; to this class belong the spleen, the stomach, and the small 
 intestines. Others have a less complete covering, so that a portion of their surface is 
 in immediate relation with surrounding parts : of this number are the ascending and de- 
 scending colon and the caecum. Lastly, others have only very slight relations with the 
 peritoneum, which merely pass over them, and do not appear to enter into their forma- 
 
 * In many subjects the existence of the sac of the omentum may be demonstrated by introducing a large 
 catheter into the foramen of Winslow, and by blowing carefully through it ; the air will enter between the 
 two anterior and the two posterior layers of the great omentum, and form a large and more or less regular 
 'iladder. For this experiment to succeed, the omentum must be parfectlv uninjured, and free from adhesions. 
 
478 SPLANCHNOLOGY. 
 
 tion : to this class belong the bladder, the lower part of the rectum, the pancreas, the 
 two lower portions of the duodenum, and the kidneys. To the last-named organs the 
 peritoneum is connected only by very loose cellular tissue. 
 
 The visceral portion of the peritoneum is not strengthened by the fibrous layer met 
 with in its parietal portion, and, therefore, perforation of the serous coat of the viscera 
 is much more common than perforation of the parietal portion of the serous membrane. 
 
 The Folds of the Peritoneum. — Among the folds of the peritoneum, most of which have 
 been already described, and which need be only recapitulated here, some bear the name 
 of ligaments, viz., the triangular, coronary, and falciform ligaments of the liver, the pos- 
 terior ligaments of the bladder, and the broad ligaments of the uterus. 
 
 Others are called mesenteries, viz., the mesentery, properly so called, or the mesentery 
 of the small intestine, the transverse mesocolon, the right and left lumbar mesocolon 
 when they exist, the ihac mesocolon, and the mesorectum. With these we should in- 
 clude the duplicature extending from the transverse fissure of the liver to the lower cur- 
 vature of the stomach, and known as the lesser omentum ; it really constitutes the me- 
 sogastrium. 
 
 Lastly, there are certain folds, named omenta or epiploa {em, upon, n?Ju, to float), viz., 
 the great, or gastro-colic, small, or gastro-hepatic, gastro-splenic, and colic omenta.* 
 With this class we may connect the appendices epiploicae. It may be well to make a 
 few observations upon the great and lesser omenta. 
 
 The Great Omentum. — The great or gastro-colic omentum, so called because it is at- 
 tached, on the one hand, to the stomach, and on the other to the colon, scarcely exists 
 in the new-born infant ; it is gradually developed as age advances, and about the period 
 of the termination of growth it reaches to the brim of the pelvis. It has been remarked 
 that it descends a little lower on the left than on the right side. 
 
 When the stomach and the colon are distended, this omentum is reduced to a more or 
 less narrow border extending along the arch of the colon. 
 
 It presents also a number of individual varieties : sometimes it is very regularly sus- 
 pended in front of the intestinal convolutions ; sometimes it is folded upon itself, and 
 carried to one side or the other ; occasionally it adheres at some point, becomes stretch- 
 ed hke a cord, and may then give rise to strangulation ; and, lastly, it is not very rare to 
 find it turned upward and backward between the diaphragm above and the stomach and 
 liver below. 
 
 It is so transparent and thin that it is difficult to conceive it to be formed of four lay- 
 ers. In some individuals it is even perforated with holes like a piece of lace. The 
 great omentum is found, in very fat persons, to be loaded with an immense quantity of 
 adipose tissue, deposited chiefly along the vessels ; so that it may acquire a very con- 
 siderable size, and a weight of several pounds. 
 
 The great omentum has an anterior and posterior surface, both of which are free, an 
 upper adherent border, a lower border, free, convex, and more or less sinuous, which cor- 
 responds with the crural arches, and the internal openings of the inguinal canals ; it is, 
 therefore, very often found in hernial sacs. 
 
 The lower border is more liable to adhesions than any other part of the omentum. 
 The lateral borders have nothing remarkable ; they proceed parallel to the ascending and 
 descending portions of the colon, which are sometimes covered by them. 
 
 The arteries of the great omentum are furnished by the right and left gastro-epiploic 
 arteries ; they descend vertically between its two anterior layers, scarcely diminishing 
 in caliber. At its lower border they turn upward, and ascend between the two posterior 
 layers as far as the arch of the colon, where they communicate with the arteries of that 
 intestine. 
 
 The veitis follow the same course as the arteries, and assist in forming the vena portee. 
 
 Some lymphatic glands are found in the great omentum along the curvatures of the 
 stomach and the arch of the colon. 
 
 Nerves. — Some nervous filaments from the solar plexus can be traced upon the arter- 
 ies of the omentirai ; it is doubtless from them that the epiploon derives its peculiar sen- 
 sibility, and on them that the phenomena of strangulation depend when it is constricted 
 in a hernia. 
 
 The uses of the omentum are not known. 
 
 The Lesser Omentum. — The lesser omentum, a true mesentery, the mesogastrium, pre- 
 sents a lower concave border, attached to the lesser curvature of the stomach, and an 
 upper border, attached to the transverse fissure of the liver, to that part of the antero- 
 posterior fissure which is behind the transverse fissure, and also to the oesophagus and 
 the diaphragm ; its right border contains the ducts and vessels of the liver, and behind 
 the border thus formed is seen the foramen of Winslow ; on the left it is bounded by the 
 cesophagus.t 
 
 ' [The colic omentum consists of two layers of peritoneum, with intermediate vessels and fat, which de- 
 scend, behind the great omentum, from the upper part of the ascending colon.] 
 
 t [The cellular tissue surrounding the vessels, ducts, and nerves, contained between the layers of this small 
 omentum, has been described as giving origin to Glisson's capsule.] 
 
THE HEART. 479 
 
 IStruetin-e of the Peritoneum. — ^The peritoneum, like all other serous membranes, has 
 neither arteries, veins, nor nerves. Those which are contained within the omenta and 
 the mesentery do not properly belong to this membrane. The finest capillary injections, 
 either natural or artificieil, form an extremely delicate network below the peritoneum, 
 but never penetrate it.* 
 
 ANGEIOLOGY. 
 
 Definition and Objects of Angeiology. 
 
 Angeiologt {ayyelov, a vessel) is that division of anatomy which treats of the orgauL 
 of the circulation. 
 
 The circulating system consists of a central organ, the heart, the agent for propelling 
 the blood ; of the arteries, vessels through which the blood is conveyed from the heart 
 to all parts of the body ; of the veins, through which the blood is returned from all parts 
 of the body to the heart again ; and, lastly, of the lymphatic vessels, appendages of the 
 venous system, into which their contents are ultimately poured. 
 
 THE HEART. 
 
 General Description. — External and Internal Conformation. — Structure. — Development. — 
 Functions. — The Pericardium. 
 
 Dissection. — In order to study the external conformation of the heart, inject the cavi- 
 ties of the right side of that organ by the pulmonary artery, or by one of the venae cavae, 
 taking care to tie the other ; the cavities of the left side may be filled from the aorta, or 
 one of the pulmonary veins. 
 
 Tallow, wax, and glue-size are the most suitable materials for this purpose. 
 
 The heart {Kapdia), the central part of the circulating apparatus, is a hollow muscular 
 organ, divided into several compartments, and intended for propelling through the arter- 
 ies into all parts of the body the blood which is poured into it from the veins. 
 
 The heart is one of the most important organs in the body. In a zoological point of 
 view, the presence or absence of a heart, and the complexity or simplicity of its struc- 
 ture, deserve particular attention, because such variations in regard to the central organ 
 of the circulation are accompanied by very great modifications in the entire organism.! 
 
 Congenital absence of the heart is extremely rare, and is always accompanied with 
 other malformations, more especially with absence of the brain. These deficiencies are 
 incompatible with life. 
 
 Number. — Man and vertebrated animals have only one heart ; in moUusca it is double, 
 or even triple. This plurality of hearts, instead of being an index of perfection, should 
 be regarded as a subdivision, and less perfect condition of the organ. We shall see that 
 man, as well as mammalia and birds, has, in reality, two hearts united into one. 
 
 Situation. — The heart is situated at the junction of the upper third with the lower two 
 thirds of the body ; hence the upper parts of the system are more immediately under the 
 influence of this important organ, t 
 
 The heart (/, fig. 170 ; o,fig. 171) occupies the middle of the thoracic cavity ; it is sit- 
 uated in the mediastinum, in front of the vertebral column, behind the sternum, which 
 forms a kind of shield for it, and beyond which it projects on the left side ; it is placed 
 between the lungs, and above the diaphragm, by which it is separated from the abdom- 
 inal viscera. 
 
 It is retained in this situation by the pericardium (p p,fig. 170), a fibro-serous cover- 
 ing, which is itself closely adherent to the diaphragm (x) ; by the pleurae {q q), which are 
 reflected on each side of it, to form the parietes of the mediastinum ; and, lastly, by the 
 great vessels which pass out or enter at its base. 
 
 * [The basis of the peritoneum is cellular tissue ; its smooth surface is covered with a squamous epithelium.] 
 t Vertebrata and mollusca are the only animals which are provided with a heart. Mammalia and birds 
 
 alone possess a double heart, i. e., a heart with two auricles and two ventricles. Fishes and reptiles have a 
 simple heart, t. e., a heart with only one auricle and one ventricle, this ventricle being pulmonary in fishes, 
 and both systemic and pulmonary in reptiles.* 
 
 t The distance from the heart to the brain varies in different individuals, according to the length of the tho- 
 rax and the neck. This difference may amount to two inches, and may exercise some influence upon the cere- 
 bral circulation. In consequence of this observation, extreme shortness of the neck has been regarded as a 
 predisposing cause of apoplexy. 
 
 * [A central pulsating vessel is found in some of the higher radiata, and in the articulata ; in some of the 
 latter it constitutes a strong muscular ventricle, but the addition of a systemic auricle to this ventricle is first 
 observed in the mollusca ; in the invertebrata, generally, the ventricle is entirely systemic : in the higher ce- 
 phalopods there are two branchial hearts. In fishes the heart consists of a systemic auricle and a pulmonary 
 ventricle, and is preceded by a sinus venosus, and followed by a bulbus arteriosus. In the early condition of 
 the batrachia the same conformation exists ; but in their adult state, and also in all reptilia, there are two 
 auricles and one ventricle, the additional auricle being pulmonary, i. e., receiving the blood from the lungs. 
 In the higher reptilia, the single ventricle, which is both systemic and pulmonary, is divided by an imperfect 
 leptura ascending from the apex of the heart. In the crocodilus lucius, as well as in birds and mammalia, 
 this interventricular septum is complete, so that in them the heart is divided into two auricles and two ventri- 
 cles, the cavities of one side being systemic, and of the other pulmonary.] 
 
ANGEIOLOGY. 
 
 These means of attachment are not such as to prevent the heart from undergoing re 
 markable changes of position, depending upon peculiar attitudes, upon shocks acting on 
 the body, or upon diseases of the surrounding organs. Thus, in a case of hydrothorax 
 on the left side, the apex of the heart struck against the right side, and gave rise to the 
 suspicion that the viscera were transposed. 
 
 Size and Weight. — Neither the size nor the weight of the heart can be estimated with 
 exactness, on account of the numerous individual varieties in both. It is very difficult to 
 determine the limits, in either the one or the other, between a healthy and a morbid con- 
 dition ; and a heart which would be considered normal in one individual would be re- 
 garded as hypertrophied in another. 
 
 The defects of the method proposed by Laennec for obtaining an approximative esti- 
 mate of the size of the heart, by comparing it with that of the closed hand of the samo 
 subject, afford sufficient evidence of the difficulty of arriving at an accurate result in this 
 matter.* 
 
 No organ in the body is more subject to enlargement than the heart ; when caused by 
 dilatation of the cavities, it constitutes aneurism of the heart {dilatation) ; when due to 
 thickening of the parietes, it is termed hypertrophy. When enlargement occurs from 
 both these causes, the heart acquires an enormous size, and has been called bullock's 
 heart (hypertrophy with dilatation). 
 
 The size of the heart may be estimated directly by ascertaining the quantity of water 
 displaced by it, and by admeasurement ; it may also be determined, in an approximate 
 manner, by its weight, which bears a certain relation to the size. 
 
 In making these estimates, it is necessary to distinguish the size and weight depend- 
 ant upon thickness of the parietes of the heart, from the increase occasioned by blood 
 contained in its cavities. In order to obtain comparative results upon this point, the 
 heart must be weighed and measured both in its empty and its distended state. The 
 average weight of the empty heart is from seven to eight ounces. Some atrophied hearts 
 do not weigh more than two ounces : dilated and hypertrophied hearts, when empty, 
 may weigh twenty-two ounces. The ordinary weight of the heart distended with tal 
 low is twenty-four ounces. I have seen dilated hearts, also, filled with tallow, which 
 weighed three pounds. 
 
 As to the admeasurement, we shall apply it in succession to the ventricles and to the 
 auricles. 
 
 Form, Direction, and Divisions. — The heart has the form of a flattened cone, the axis 
 of which is directed obliquely from above downward, from the right to the left side, and 
 from behind forward. This direction, which is peculiar to the human species (for in the 
 lower animals the heart is vertical), appears to have some relation to the erect position. 
 The heart is not symmetrical in reference to the median line of the body, nor yet in re- 
 gard to its own axis. 
 
 The general relations of the heart will be indicated when we describe the pericardium. 
 I shall here simply state that the heart is in relation with the left lobe of the lungs, which 
 is deeply notched to receive it ; that that portion of the heart which is uncovered in front 
 between the lungs, after the sternum and the ribs have been removed, is extremely vari- 
 able in different subjects ; that independently of the volume of the heart, the adhesions 
 of the lungs exercise a very great influence upon the extent of these direct relations of 
 the heart with the anterior part of the sternum. In an old woman, whose lungs were 
 closely adhering to the walls of the thorax, the anterior face of the heart was almost en- 
 tirely bare behind the sternum and the cartilages of the ribs on the left side.t That the 
 posterior face of the heart deserves the name of vertebral surface just as well as that 
 of diaphragmatic surface ; that this surface occasions a marked impression upon the liv- 
 er ; that the relations of the posterior surface of the heart with the oesophagus are such 
 as will cause the distended oesophagus to raise the corresponding portion of the pericar- 
 dium, and that the posterior surface of the heart is not only separated from the vertebral 
 column by the oesophagus, but also by the aorta, which is situated between the oesopha- 
 gus and the bodies of the dorsal vertebrae. 
 
 The heart is divided into ventricles and auricles. The ventricles (Jt o,figs. 191, 192) 
 constitute the chief part, in some measure the body of the organ, the conical form of 
 which is determined by them ; the auricles (m n) are a kind of appendices, which can be 
 well seen only when the heart is raised ; they occupy the base of the organ ; the limit 
 between the auricles and the ventricles is indicated by a circular furrow. 
 
 External Conformation of the Heart. 
 The External Surface of the Ventricles. 
 The external surface of the ventricles, or the ventricular portion of the heart, called also 
 
 * The large hand of a workman does not imply the existence of a larger heart than the small hand of a fe- 
 male, or of a man exempt from manual labour. 
 
 t The heart descends as far as the middle portion of the xiphoid appendix. The upper half of this appendix 
 is, therefore, in direct relation with the heart, and the inferior half in direct relation with the liver. Should 
 not this circumstance be of some weight in explaining the acute pains by which a pressure upon this appendix 
 u accompanied ? 
 
THE HEART. 48'! 
 
 by the ancients the arterial portion, because the arteries arise from it, presents for our 
 consideration an anterior and an inferior surface, a right and a left border, a base and an 
 apex. 
 
 The anterior or sternal surface {Jig. 191) is convex, and is divided into two unequal 
 parts, a larger on the right, and a smaller on the left side, ^^ 191_ 
 
 by the anterior furrow of the heart (e b), which passes verti- 
 cally from the base towards the apex, is occupied by the an- 
 terior coronary artery, and is often obscured by fat. All 
 that part of the organ which is to the right of the furrow be- 
 longs to the right ventricle (I), all on the left belongs to the 
 left ventricle (o). The furrow itself corresponds to the sep- 
 tum between the ventricles. 
 
 This surface, or, rather, the pericardium which covers it, 
 is in relation with the sternum, more especiedly in that part 
 which hes to the right of the furrow ; also with the fourth, 
 fifth, and sixth costal cartilages of the left side, and with the 
 lungs, which cover it more or less completely. It should 
 be remarked that, in large hearts, this surface, or its peri- 
 cardium, corresponds immediately to the sternum, while in 
 the natural state it is situated at some distance from that 
 bone. The relations of the heart with the anterior wall of 
 the thorax enable us to examine its condition by means of 
 percussion and auscultation. 
 
 The inferior or diaphragmatic surface {fig. 192) is plane and horizontal ; it rests upon 
 the diaphragm, which forms a sort of floor for it, and separates it from the hver and the 
 stomach. Like the anterior surface, it is marked by a longitudinal furrow, the posterior 
 furrow of the heart {e i), which is traversed by vessels and concealed by fat. It differs 
 from the anterior furrow in running parallel to the axis of the heart, and dividing its 
 diaphragmatic surface into two nearly equal parts, excepting near the apex. In conse- 
 quence of the relations of this surface, pidsations are observed in the epigastrium, which 
 are sometimes much more distinct than those felt upon the anterior wall of the thorax. 
 Another result of these relations is, that the same meaning is attached to the terms 
 scrobiculus cordis and pit of the stomach, and also to the expressions pain at the heart, pain 
 at the stomach, 4-c. 
 
 The right or lower border is thin and horizontal, and rests upon the diaphragm ; it is 
 straight near tlft apex, but becomes convex towards the base. The left border (o b, fig. 
 191) is very thick, convex, and almost vertical; it resembles a surface rather than a 
 border, and corresponds to the left lung, which is deeply notched to receive it. 
 
 The base of the ventricular portion of the heart is turned upward, backward, and to the 
 right side. From it arises, upon an anterior plane, an artery, which immediately passes 
 from the right to the left ; this is the pulmonary artery {k) ; the portion of the ventricle 
 from which it proceeds forms a prominence on the right side of the anterior furrow of 
 the heart, and is prolonged towards the left, becoming narrower at the same time, so as 
 to form a funnel-shaped projection {infundibulum, conus arteriosus) {a), extending a little 
 beyond the base of the ventricles. Upon a second plane we find the aorta (/), the origin 
 of which, from the left ventricle, is concealed by the funnel-shaped prolongation of which 
 we have just spoken. On a third plane we find a circular furrow (o u, fig. 195), separa- 
 ting the auricles from the ventricles. Its posterior half is occupied by the coronary ar- 
 teries and veins, and the anterior and posterior furrows of the heart terminate in it at 
 right angles. 
 
 This circular furrow at first sight appears to be superficial, but is very deep in its pos- 
 terior half If we dissect carefiiUy down to the bottom of this furrow, it is found that 
 the base of each ventricle is, as it were, turned inward, so as to be in contact by a broad 
 surface with the base of the auricle. We find, also, that the base of the ventricles is cut 
 obUquely, and hence the anterior surface of the heart is longer than the posterior surface. 
 The difference in length between these two surfaces is about fifteen lines upon the right, 
 and from nine to ten Unes upon the left ventricle. Thus, in a heart of the ordinary size, 
 the length of the ventricles in front was three inches three lines, and behind two inches 
 three lines. In a very large heart the length in front was four inches, and behind only 
 three. The circumference of the base of an injected heart, of the average size, measured 
 ten inches ; that of a large heart was thirteen inches six lines. 
 
 The apex {h) or point of the heart is slightly curved backward in the majority of sub- 
 jects, and is notched opposite the junction of the two longitudinal furrows. This notch, 
 which is partially concealed by vessels and adipose tissue, divides the apex of the heart 
 into two unequal portions ; a right and a smaller, belonging to the right ventricle, and a 
 left and larger portion, belonging to the left ventricle. The relative size of the two por- 
 tions of the apex of the heart is not constant. In some cases of hypertrophy of the left 
 ventricle, the apex of the heart is entirely formed by it ; in other cases, on the contrary 
 the apex of the heart is nearly equally subdivided. 
 
 Ppp 
 
482 ANOEIOLOGY. 
 
 The apex of the heart is directed forward, downward, and to the left, and corresponds 
 to the cartilages of the fifth and sixth ribs of the left side, and therefore to the region of 
 the corresponding mamma ; the left lung is notched opposite the apex of the heart, so 
 that the latter strikes directly against the parietes of the thorax. 
 
 The External Surface of the Auricles. 
 The attricles (m n,figs. 191, 192), forming the auricular portion of the heart, are saccular 
 cavities in which the veins terminate ; they may, in fact, be regarded as dilatations of 
 those vessels, and hence this portion of the heart is called the venous portion, in contra- 
 distinction to the ventricles. They are situated upon the hindermost portion of the 
 base of the heart (fig. 192). 
 
 Their size varies in different individuals ; in an injected heart, the average height of 
 the auricular portion is two inches ; its antero-posterior diameter is nearly the same ; 
 and when the auricles are distended, its transverse diameter extends beyond the tcl 
 tricles on each side. 
 
 The shape of the auricular portion of the heart, which can only be accurately deter 
 mined by means of injection, is irregularly cuboid. It therefore presents several sur 
 faces ; its anterior surface is situated on a plane much farther back than that of the front 
 of the ventricles {fig. 191). It is concave, and describes three fourths of a circle, so as 
 to embrace the aorta and the pulmonary artery, being moulded upon those vessels, and 
 completely concealed by them. The anterior surface of the auricular portion has no 
 anterior furrow along the middle line. 
 The posterior surface (fig. 192) is convex, and is continuous with the inferior surface 
 of the ventricles ; it presents a vertical furrow, which is 
 prolonged upward from the posterior furrow of the ventri- 
 cles, then deviates to the left side, and forms a curve, the 
 concavity of which is directed towards the right ; it corre- 
 sponds to the septum of the auricles. Immediately to the 
 right of this furrow we find the termination of the vena cava 
 inferior (r), and lower down, that of the great coronary vein. 
 The posterior surface of the auricles is turned towards the 
 vertebral column, from which it is separated by the oesopha- 
 gus and the aorta. 
 
 The superior surface of the auricular portion forms the 
 highest part of the heart, and is directed backward and to- 
 wards the right side. It is divided by a furrow, which is 
 convex on the right side, is continuous with the furrow upon 
 the posterior surface, and, like it, corresponds to the inter- 
 auricular septum. Upon this surface we find the termina- 
 tions of five different veins ; one only of these is to the right 
 of the furrow, viz., that of the vena cava superior (d,fig. 191) ; the other four are on 
 the left of the furrow, and are those of the four pulmonary veins, which are arranged in 
 pairs (c c,fig. 192), two at the extreme left of the auricles belonging to the left pulmona- 
 ry veins, and two immediately in the neighbourhood of the posterior furrow belonging to 
 the right pulmonary veins. This surface corresponds to the bifurcation of the trachea, 
 which, as it were, rides upon it. 
 
 The extremities of the auricles, or the aurievJee, are free, and somewhat resemble the 
 pendulous portion of a dog's ear ; hence the term auricles. They are indented like a 
 cock's comb ; the right auricula is anterior, the left posterior. 
 
 The right auricula {c,fig. 191) is broader and shorter than the left ; it is triangular and 
 concave, so as to embrace the aorta, in front of which it projects ; the left auricula (i) is 
 narrower and longer, it is sinuous, and curved twice upon itself like an italic S ; it em- 
 braces the pulmonary artery, and terminates opposite the highest part of the anterior fur- 
 row of the ventricles. 
 
 The right auricula is continuous with the rest of the corresponding auricle, vdthout 
 any well-marked line of separation ; but the left auricula is very distinct from its auricle ; 
 and upon this latter side, the distinction pointed out by Boerhaave, between the sinuses 
 and the auricles properly so called, may be particularly observed : according to him, the 
 sinus constitutes the body of the auricle, and may be regarded as a dilatation of the veins, 
 while the auricular appendix forms the proper auricle. 
 
 The Internal Conformation of the Heart. 
 
 The heart is divided internally into four cavities, which are separated from each oth- 
 er by complete or incomplete septa ; two of these cavities belong to the auricles, and two 
 to the ventricles. There are a right ventricle and auricle, and a left ventricle and auri- 
 cle. The auricle and ventricle of the same side are separated by incomplete septa or 
 valves, and communicate with each other. The cavities of the opposite sides are sep- 
 arated by complete septa, and do not communicate. Tlie heart is therefore, in this lat- 
 ter respect, truly double. The right ventricle and auricle constitute the right heart, also 
 
THE HEART. 4^ 
 
 named the cmur d. sang noir, from the colour of the blood which it contains ; and the pul- 
 monary heart, because it propels the blood into the lungs. The left ventricle and auricle 
 constitute the left heart, called also the caur a sang rouge, or the aortic heart, because it 
 throws the blood into the aorta. 
 
 The Internal Conformation of the Ventricles. 
 
 Dissection. — In order to obtain a general idea of the internal conformation of the heart, 
 make a series of sections at right angles to its length, or else make an incision along its 
 borders parallel to its long axis. 
 
 To obtain a more exact notion of the ventricles, make a V-shaped incision in the right 
 ventricle, letting one branch of the incision extend along the anterior furrow, and tte 
 other along the right border, while the angle at which they meet should correspond to 
 the apex of the ventricle. 
 
 The best method of opening the left ventricle consists in making a vertical section 
 through the septum ; but in doing this, the right ventricle must be sacrificed. 
 
 In order to obtain a general view of the appearance of these cavities, they may be pre- 
 pared in the dried state. For this purpose, the heart is to be injected with tallow, and 
 then, after being dried sufficiently, to be opened in the manner above described, and im- 
 mersed in warm turpentine, which will dissolve the tallow,and leave the ventricles dilated. 
 
 Interior of the Right Ventricle. 
 
 The right ventricle occupies the right anterior and inferior portion of the heart, and has, 
 therefore, been called the anterior or the inferior Fig. 193. 
 
 ventricle. Its cavity (Jig. 193) has a three-sided 
 pyrjunidal form. Its inner wall (6) is convex, and 
 is formed by the septum of the ventricles ; in its 
 lower half it has a well-marked reticulated appear- 
 ance, which is almost entirely absent in the upper 
 half (a). The anterior and inferior walls (partly re- 
 moved in^. 193) are both concave, and are re- 
 markable for their thinness, so that they are al- 
 ways collapsed when the ventricle is empty. The 
 base of this ventricle presents two openings, which 
 are separated from each other by a projecting part, 
 and which may be compared to the wide circular 
 end, and the narrow mouthpiece of a huntsman's 
 horn. The opening into the auricle (in which a 
 bristle is placed) corresponds to the wide end of 
 the horn, and the infundibulum (a) to the narrower 
 end. The transverse diameter of the base of this 
 ventricle is nearly equal to its height. The sum- 
 rait (Z) is turned towards the apex of the heart. 
 
 The walls of the right ventricle are very remark- 
 able for their reticulated or areolar character ; this 
 areolar portion might be termed the corpus cavernosum of the heart, for it presents the 
 spongy structure of the erectile tissues. The fleshy columns which form the areolae are 
 observed not only upon each of the walls of the ventricle, but they also pass across the 
 cavity of the ventricle near its summit, extending from one wall to the other ; in conse- 
 quence of which the capacity of the ventricle is singularly diminished. 
 
 The cylindrical fleshy columns {columnce carnece, teretes lacerti), which separate the 
 meshes or areolae, are of three kinds. Some (c) are attached to the parietes of the heart 
 by one of their extremities, and are free in the rest of their extent ; they terminate by a 
 kind of simple or double meimmillated projection, from which proceed small tendinous 
 cords {chorda tendinem), that are inserted into the auriculo-ventricular valves (c). They 
 are very few in number, and have been named the muscles of the heart {musculi papillares). 
 The fleshy columns of the second kind are free throughout the whole of their extent, ex- 
 cepting at their extremities, which are attached to the walls of the ventricle. These col- 
 umns, which are the most numerous, are divided and subdivided to form the areolae. The 
 third kind of columnae carneae adhere to the walls of the ventricle by one of their sides ; 
 they are therefore sculptured like pilasters upon the walls of the ventricle. 
 
 Most of the colmnnae carneae pass from the apex towards the base of the heart. In 
 all their free portion, the columns of the two first kinds are attached to each other or to 
 the walls of the ventricle, by means of small tendinous cords, which are much more deli- 
 cate than those proceeding to the valves. The areolar muscular structure just described 
 is the essential constituent of the walls of the ventricle ; but in addition to it there is a 
 rather thin, compact, and non-reticulated layer of superficial fibres, on which depends 
 the smooth appearance of the external surface of the ventricle. 
 
 The Orifices of the Right Ventricle. — At the base of the right ventricle there are two 
 orifices, one auricular, which establishes a communication between the ventricle and the 
 
ANGEIOLOGY. 
 
 auricle ; the other arterial, which leads into the pulmonary artery. They are both fur- 
 nished with valves. 
 
 The right auricular or auriculo-ventricular orifice (through which the bristle is inserted, 
 Fig. 194. fig. 193) is placed at the posterior and right part of the base of 
 
 the ventricle ; it is elliptical, and is provided with a mem- 
 branous structure, called the tricuspid or triglochin valve (c), 
 which projects into the interior of the ventricle. This valve 
 is of an annular form (annulus valvulosus). Its ventricular sur- 
 face {t 1 1, fig. 194) is directed towards the parietes of the ven- 
 tricle, and receives a great number of small tendinous cords, 
 which, being attached to it at different points, give it an ir- 
 ^ regular aspect. Its auricular surface {t t t,fig. 195), which is 
 turned towards the axis of the ventricle, is smooth. The ad- 
 herent border is fixed to the margin of the auricular orifice. 
 The free border or margin forms a ring, the diameter of which is equal to that of the 
 .gg adherent border : this margin is irregularly divided, so that, in- 
 
 ''^' ■ stead of the three segments {t 1 1) generally described, and from 
 
 which the name of the valve has been derived {rpelc, tres, three, 
 and y^uxk, cuspis, a point), some authors admit four, or even 
 six segments. 
 
 The construction of the tricuspid valve can be understood 
 only by regarding it as composed of two parts, an anterior, cor- 
 responding to the anterior half of the elliptical auriculo-ventric- 
 ular orifice, and a posterior, corresponding to the posterior 
 half of the same. The tricuspid valve is not unfrequently in- 
 terrupted on the left side opposite the junction of these two 
 valves. This valve might, with as much propriety, be termed mitral, as that which is 
 attached to the lefl auriculo-ventricular opening. 
 
 To the free margin of the valve, upon which some small nodules are occasionally 
 found, are attached a number of tendinous cords of a nacreous aspect, which are ex- 
 tremely strong considering their tenuity. These small cords, or, rather, tendinous fila- 
 ments, always arise in greater or less number from the summits of the columnae car- 
 nese ; diverging from thence, often bifurcating during their course, and sometimes be- 
 coming united together, they terminate, some at the free margin, others at the ventric- 
 ular surface of the valve, and others, again, at its adherent border. 
 
 All the smalll tendinous cords do not arise from the columnae cameas of the first kind ; 
 many of them proceed directly from the parietes of the heart. We constantly find a 
 fasciculus of diverging cords arising from the septum. 
 
 These cords are so arranged, that, by drawing upon them, the valve is depressed and 
 stretched. We find, in fact, that both in the anterior and posterior part of the tricuspid 
 valve, those cords which arise from the free margin on one side converge towards those 
 of the opposite side, some even crossing each other in the form of the letter X. 
 
 The arterial or pulmonary orifice {ostium arteriosum, d,fig. 194) is placed at the anterior 
 
 Fig. 196. 
 
 part of the left side of the base of the right ventricle. It is sep- 
 arated from the auricular orifice by a tolerably prominent mus- 
 cular band, which is concave on its lower surface, and divides 
 the right ventricle into two portions, an auricular and a puhno- 
 nary portion or infundibulum. This orifice is circular, and is 
 provided with three very distinct valves, which are named sig- 
 moid or semilunar {f,fig. 195 ; a a a, fig. 196).* Although thin 
 and semi-transparent, they are very strong. They are directed 
 vertically as the blood is passing from the ventricle into the 
 artery, and become horizontal when it tends to flow back from 
 the artery into the ventricle. Of their two surfaces, the ven- 
 tricular corresponds to the .cavity of the ventricle ; the other, or 
 arterial surface, includes between it and the walls of the artery 
 a small cul-de-sac, which has been compared to a pigeon's nest. 
 The adherent border of each valve is convex, and directed to- 
 wards the ventricle ; its free margin presents in the middle a 
 small nodule, by which it is divided into two semilunar halves. 
 When depressed, the valves completely close the vessel, the 
 three nodules filling up the triangular interval left between the approximated free mar- 
 gins. These valves must, therefore, oppose the reflux of the blood into the ventricle ; 
 but the resistance offered by them is easily overcome by an injection thrown into the 
 pulmonary artery. 
 
 Interior of the Left Ventricle. 
 The left ventricle occupies the left upper and back part of the heart ; it is evidently 
 
 * It is extremely rare to find any anomaly in the number of these valves, either by an increase or a dinu 
 BUtion of them. 
 
THE HEART. 485 
 
 constructed upon the same fundamental type as the right ventricle, but difFers from il 
 in many respects, as we shall now proceed to show. 
 
 Difference in Situation. — The different positions of the two ventricles are sufficient- 
 ly known from what has already been stated ; but it is important to remark, that the 
 left ventricle projects beyond the other at the apex of the heart {fig. 197), while the 
 right is more prominent at the base, in consequence of the existence of the infundibulum. 
 
 Difference in Shape. — The right ventricle is pyramidal, and becomes collapsed when 
 not distended ; the left is conical and convex, not only on its free surface (6), but even 
 at the septum (a, fig. 194), where it seems to project into the interior of the right ven- 
 tricle. 
 
 Difference in Size. — It is generally stated, in accordance with Senac, Winslow, and 
 Haller, that the right ventricle is more capacious than the left : this statement is found- 
 ed upon direct observation, which proves that the right ventricle gains more at the base 
 than the left does at the apex ; also upon deductions made by comparing the right auri- 
 cle and the pulmonary artery with the left auricle and the aorta ; and, lastly, upon the 
 results obtained by injecting the cavities of the heart. No two observers agree as to 
 the exact numbers which would represent the capacities of the two ventricles, as the 
 following different estimates will show. The capacity of the left ventricle to that of the 
 right has been stated as 31 to 33, as 10 to 11, as 5 to 6, as 2 to 3, and as 1 to 2. — {Hol- 
 ler, t. i., 1. iv., sect. 3, p. 327 ) 
 
 Now the discrepancies in these estimates prove either the deficiency of the methods 
 of observation, or the existence of real differences resulting from a greater or less amount 
 of accidental obstruction to the pulmonary circulation occurring shortly before death. 
 In the great majority of subjects, the right ventricle is proved to be more capacious than 
 the left, and this, according to the judicious remark of Sabatier, depends upon the state 
 of the circulation through the heart during the last moments of life, at which time the 
 blood flows back from the lungs into the right ventricle, while the left ventricle, not ex- 
 periencing a similar obstruction, and, moreover, acting with greater vigour, empties it- 
 self, more or less completely, of the blood contained within it. After death by decapita- 
 tion, the right ventricle is as much contracted as the left ; also, in individuals that 
 have died without any agony or exhaustion, the cavity of the left ventricle has been com- 
 pletely contracted.* 
 
 The condition of the heart, then, in the dead body, in which that organ is found as it 
 was at the moment of death, affords us no means of judging of the relative capacity of 
 its cavities during life. If, by tying the aorta in a living animal, we cause stagnation of 
 the blood in the left ventricle, while the exit of that fluid from the right cavities through 
 the pulmonary artery remains unimpeded, the relative capacity of the two ventricles will 
 be found to be exactly the reverse of what is generally indicated. 
 
 The gradual injection of the heart with wax or tallow, so as to distend the ventricles 
 without producing laceration, enables us to determine the size and the weight of the 
 mass of injection contained within each cavity of the heart, and also to measure these 
 cavities under similar conditions, that is to say, in a state of distension. From obser- 
 vations which I have made in this way, it appeared that the left ventricle was rather 
 more capacious than the right. 
 
 Difference in the Appearance of the Cavity and in the Structure of its Parietes. — In the 
 left ventricle we find the three kinds of columnas carneae. Of 
 the columns of the first kind there are only two (i i,fig. 197), 
 which are remarkable for their great size. Their summits are 
 almost always bifurcated, and sometimes they are divided into 
 three parts ; not unfrequently each of these columnae results 
 from the apposition of two or three others, which are united 
 by small fibrous cords or filaments. 
 
 The fleshy columns of the second kind are smaller in the 
 left than in the right ventricle. The areolar arrangement is 
 less strongly marked, and is observed only in the innermost 
 layer, excepting always at the apex, the whole thickness of 
 which, with the exception of the most superficial layer, pre- 
 sents the cavernous arrangement. Moreover, the areolae are 
 remarkable for their small size, and for the slenderness and 
 jiumber of the columnae by which they are surrounded. These 
 muscular areolae are often completed by fibrous cords. 
 
 Difference in Thickness. — The walls of the left ventricle are 
 much thicker than those of the right {figs. 193, 194, 197). The proportion of one to two, 
 arrived at by Laennec#is too slight ; it is one to four, or even one to five. It is gener- 
 ally said that the muscular tissue of the heart is more compact on the left than on the 
 right side. 
 
 * The concentric hypertrophy mentioned by authors appears to apply to ordinary hearts, or to hearts in « 
 state of hypertrophy, with their cavities closed, in conseqaence of the eontraction continuing to the last mo- 
 ment. I, therefore, am opposed to admitting concentric liypertrophy as a pathologioal state. 
 
486 ANGEIOLOGY. 
 
 Difference in the Orifices. — The left auriculo-ventricular orifice (through which a bristle 
 is inserted, ^o'. 197) exactly resembles the right one, and, like it, is provided with a 
 valve {g) analogous to the tricuspid, and named by Vesalius the mitral valve, from its 
 being regularly divided into two opposite segments {mm, figs. 194, 195). The mitral 
 valve is stronger than the tricuspid, it is thick<|- and longer, and receives stronger and 
 more numerous chordae tendineae. These differences are more particularly observed in 
 the right segment of the mitral valve, which projects, like an incomplete septum, into 
 the cavity of the ventricle, and appears to divide it into an aortic and an auricular por- 
 tion ; the left segment of the valve {g,fig. 196), on the contrary, is applied against the 
 walls of the ventricle. 
 
 The aortic orifice {e,fig. 194) exactly resembles the pulmonary orifice of the right ven- 
 tricle ; like that opening, it is also provided with three sigmoid valves (e, fig. 195), which 
 differ from those of the pulmonary artery merely in being stronger, and in having larger 
 nodules or globules upon their free borders ; and, as Arantius admitted their existence 
 only in these valves, they are therefore called globuli, noduli or corpora Arantii.* 
 
 The right auriculo-ventricular and arterial orifices are placed at a" distance from each 
 other, but the corresponding orifices of the left side are contiguous, so that the adherent 
 border of the right half of the mitral valve is continuous with the adherent border of the 
 corresponding sigmoid valve ; and hence it follows, that when these valves are removed, 
 the base of the ventricle presents only one orifice. 
 
 Interior of the Jiuricles. 
 
 Dissection of the Right Auricle. — Make a horizontal incision from the auricula to the 
 inferior vena cava, and then a vertical one from the vena cava superior perpendicularly 
 to the first. 
 
 Of the Left Auricle. — ^Make a vertical incision from before backward, between the 
 right and left pulmonary veins, including the entire posterior wall of the auricle. In or- 
 der to have an accurate idea of the shape of the interior of the auricles, inject a heart 
 with tallow or wax, and then examine the cast thus taken of their cavities. 
 
 Interior of the Right Auricle. 
 
 The shape of the right auricle, when distended, may be compared to the segment of 
 an irregular oval, the long diameter of which is directed from before backward. It has 
 three walls : an anterior, which is convex ; an internal, which is slightly concave, and 
 corresponds to the septum ; and a posterior, also concave, which forms the greatest part 
 of the auricle, and is remarkable for the existence upon it of fleshy columns. The right 
 auricle has four orifices. in the adult, and five in the foetus, viz., the auriculo-ventricular 
 orifice, the opening of the vena cava superior, that of the vena cava inferior, that of the 
 coronary vein, and, in the foetus, the foramen ovale (trou de Botal), the situation of which 
 is occupied in the adult by the fossa ovalis. 
 
 The auriculo-ventricular wifice {see fig. 195), the largest of all, is of an elliptical form, 
 from sixteen to eighteen lines in its longest diameter, which is from before backward, 
 and about twelve lines in its shortest diameter. It is surrounded by a whitish zone 
 (a q), to which is attached the adherent border of the tricuspid valve {t 1 1). The cavity 
 of the auricle presents a sort of constriction opposite the auriculo-ventricular orifice. 
 
 The orifi.ce {h,fig. 193) of the vena cava superior {d) is circular, and is directed down- 
 ward and a little backward ; it has no valves ; it is bounded on the left by a projecting 
 muscular band, which separates it from the auricle, and on the right by a less prominent 
 band intervening between it and the vena cava inferior. The former of these two bands, 
 which are distinctly marked upon the cast of wax, separates the fasciculated portion of 
 the auricle from the non-fasciculated portion, which seems to be formed by an expansion 
 of the venae cavae. 
 
 The orifice (?) of the vena cava inferior (r) opens into the auricle, near the septum, not 
 perpendicularly upward, but horizontally, and at right angles to the original direction of 
 the vein, which is vertical. The orifice is circular, and larger than that of the superior 
 cava ; the inferior cava sometimes forms an ampulla or dilatation before it enters the 
 auricle ; us orince, unlike that of the superior cava, is provided with a remarkable semi- 
 lunar valve, the valvula Eustachii (n), which surrounds the anterior half, and sometimes 
 two thirds of this opening. Its free margin is concave, and directed upward ; its adhe- 
 rent border is convex, and directed downward : one of its surfaces is turned forward to- 
 wards ihe auricle, the other backward towards the vessel ; one of its extremities ap- 
 pears to be continuous with the margin of the fossa ovalis (*), and the other is lost upon 
 the margin of the opening of the inferior cava. 
 
 The valve of Eustachius closes the orifice of that vein very imperfectly. In its upper 
 two thirds it is extremely thin, and resembles the valves of the veins ; its lower third 
 contains a muscular fasciculus. 
 
 * The three sigmoid valves of the aorta are generally very similar in form ; in one case, however, which I 
 examined, one of these valves had twice the size of the others. I have lately observed, in a man of sixty, who 
 died of a disease of the heart, the rare sight of an aorta provided with only two sigmoid valves ; these two 
 mlves were very large, and ia relation with the diameter of the aortic orifice, which they covered completely 
 
THE HEART. 487 
 
 The orifice of the coronary vein is placed immediately in front of the preceding, from 
 which it is separated by the Eustachian valve. It is sometimes situated at the bottom 
 of a small cavity or vestibule. It is provided with a very thin semilunar valve {valvula 
 Thebesii, below and behind the bristle), which exactly resembles the valves of the veins, 
 and completely covers the mouth of the vessel. The upper extremity of this valve is 
 continuous with the lower end of the Eustachian valve. 
 
 The Inter-auricular Orifice. — In the foetus, the inter-auricular septum is perforated be- 
 hind and below by an opening improperly called the foramen of Botal, for it was known to 
 Galen, who described a free communication between the auricles. After birth, we find 
 in the situation of the foramen ovale a fossa {fossa ovalis, vestigium foramims ovalis), or, 
 rather, a plane surface, which is generally smooth, but occasionally uneven, and, as it 
 were, reticulated ; it is bounded in front and above by a semicircular ridge or border (s), 
 which is improperly called the isthmus or annulusVieussenii, and may be regarded as a more 
 or less perfect sphincter. Behind, the fossa ovalis is continuous with the vena cava in- 
 ferior ; the semicircular ridge or border of the fossa ovalis is formed by a curved mus- 
 cular fasciculus, sometimes very thick, the concavity of which is directed backward ; 
 the inferior extremity of the fasciculus is continuous with the Eustachian valve. 
 
 The fossa ovalis is frequently found to be prolonged beneath the semicircular border 
 or annulus, so as to form a sort of cul-de-sac, the bottom of which is often perforated, 
 and the handle of a scalpel may not unfrequently be introduced through this opening 
 into the left auricle, although no morbid phenomenon may have been observed during 
 life. 
 
 The Fasciculated and Reticulated Portion of the Auricle. — Upon the internal surface of 
 the auricle, to the right of the vena cava, are observed certain muscular fasciculi or 
 fleshy columns (musculi pectinati auricula,), which are directed vertically from the auric- 
 ula towards the auriculo-ventricular orifice. These fasciculi adhere to the auricle on 
 one side only ; they are intersected by other oblique and smaller bundles, which give a 
 reticulated aspect to the inner surface of the auricle. 
 
 Cavity of the Auricula. — The auricula, or that portion of the auricle which extends 
 from the vena cava superior to the bottom of the appendix, consists of an areolar or cav- 
 ernous structure, exactly resembling that which has been described in the ventricles. 
 The same cavernous structure is found in other parts of the auricle, and in particulai 
 near the orifice of the coronary vein. 
 
 I agree with Haller* and Boyer, in denying the existence of the tubercle of Lower, 
 described by that anatomist as situated (at m) between the openings of the venae cavse. 
 
 It is generally admitted that a certain number of small veins open into the right auri- 
 cle by minute orifices without valves. We find, in fact, some openings resembling vas- 
 cular orifices, and known under the name of the foramina Thebesii ; they are constantly 
 found below the orifice of the vena cava superior, but most of them only lead into small 
 groups of areolae, and injections do not demonstrate the existence of any corresponding 
 vessels. The only true vascular orifices are those for the anterior coronary veins. 
 
 Interior of the Left Auricle. 
 
 The cavity of the left auricle (fig. 197) differs from that of the right in the following 
 circumstances : in being less capacious than the right auricle, the proportion between 
 them being four to five ; in its form, which is irregularly cuboid ; in the number of its 
 orifices, of which there are five after birth, and six in the fcetus ; in the character of 
 those orifices : thus the left auriculo-ventricular orifice (see fig. 195) is smaller than the 
 right ; its long diameter, which is transverse, is from thirteen to fourteen lines, its short 
 diameter is from nine to ten lines ; the four other openings belong to the pulmonary veins, 
 two (c) on the right, and two (c c) on the left side, and all are without valves ;t in the 
 structure of its auricula, which is perfectly distinct from the rest of the auricle, and con- 
 tains a central conical cavity, leading into the auricle by a well-defined circular open- 
 ing ; in the left auricle, nothing is seen on the septum corresponding to the fossa ovalis,t 
 at least we perceive neither band nor ring by which it is circumscribed. When the two 
 auricles communicate by an oblique passage, we find a very thin fibrous band, beneath 
 which the scalpel may be introduced into the right auricle. 
 
 Structure op the Heart. 
 
 The heart is essentially a muscular organ, and has a framework consisting of certain 
 fibrous rings or zones ; it is covered by a layer of serous membrane ; the left cavities 
 are lined by a membrane continuous with the internal coat of the arteries, and the right 
 
 * " Id tuberculum cupide receptum est, ut fere fit, ab iis scriptoribug quibus occasio ad propria experimenta 
 nulla est,deinde etiam abiis qui tandem omnin(Jiu corporibus humanis dissecandis se exercuerunt." — (Ualler 
 Elem. Phys., t. i., lib. iv., sect. 2, p. 314.) 
 
 t It is not uncommon to meet with five openings, three on the right and two on the left side ; in other cases, 
 the two left pulmonary veins open by a common orifice. 
 
 t [The situation of the foetal opening {a. Jig. 197) is very commonly indicated by a recess of variable depth 
 opening between the left surface of the septum and the (still free) crescentic border ofhbe valve of the fora- 
 men ovale.] 
 
488 ANGEIOLOGY. 
 
 cavities by one continuous with the lining membrane of the veins.* Some nerves, prop- 
 er vessels, and cellular tissue, also enter into its structure. 
 
 The Framework of the Heart. 
 
 This term may be applied to foxxx fibrous zones (the tendinous circles of Lower), which 
 may be regarded as affording both origin and insertion to all the muscular fibres of the 
 heart. These zones are situated at the four orifices of the ventricles, viz., the two au- 
 riculo-ventricular and the two arterial orifices. 
 
 Dissection. — Remove with care the adipose tissue, and the vessels which occupy the 
 furrows of the heart. Examine the fibrous zones from the internal surface of the heart 
 In order to study the relations of the orifices with each other, remove the auricles, the 
 aorta, and the pulmonary artery, a little above those orifices. 
 
 The Auriculo-ventricular Zones. — Each auriculo-ventricular zone is a tolerably regular 
 fibrous circle, which surrounds the opening between the auricle and ventricle, and de- 
 termines its form and dimensions. These fibrous circles give off expansions of a sim- 
 ilar nature, which enter into the formation of the tricuspid and mitral valves, and thus 
 add to their strength. The chordae tendineae of the heart also terminate in these zones, 
 either directly or through the medium of the valves. 
 
 The left auriculo-ventricular zone is stronger than the right. 
 
 The Arterial Zones. — These are two circular rings, the diameter of each of which is 
 somewhat less than that of its corresponding artery, so that there are some very distinct 
 folds or wrinkles produced. These two zones are exactly alike in form, but differ some- 
 what in strength, the aortic being stronger than the pulmonary. From these zones are 
 given off three very thin but very strong prolongations, which occupy the angular inter- 
 vals formed by the indented border by which the aorta and pulmonary artery commence ; 
 and three other prolongations extend into the substance of the sigmoid valves. These 
 prolongations form very distinct fibrous bundles in the sigmoid valve of the aorta.t 
 
 Relative Position of t'he Orifices of the Ventricles (see fig. 195). — The two auriculo-ven- 
 tricular orifices are situated upon the same plane, posterior to the other orifices, and ap- 
 proach each other at their middle. 
 
 The long diameters of these two orifices are at right angles to each other : thus, the 
 long diameter of the right auriculo-ventricular orifice is directed from before backward, 
 while that of the left orifice is directed transversely. 
 
 In the angular interval left between these two orifices in front, the aortic opening (f) 
 is closely united to them both ; so that the posterior half of the circumference of the aor- 
 tic zone is blended with both auriculo-ventricular zones. At the point of junction be- 
 tween them, we find a cartilaginous, and in the larger animals a bony, arch, which was 
 described by the ancients under the name of the bone of the heart : in this situation, also, 
 we frequently find the ossiform concretions of the orifices. 
 
 Lastly, upon a plane in front and on the left of the aortic opening, and about five or 
 six lines above it, is situated the orifice (/) of the pulmonary artery. 
 
 The orifice of the aorta is directed towards the right side, that of the pulmonary ai- 
 tery towards the left, so that these two vessels cross each other, so as to represent the 
 letter X. It follows, therefore, that the pulmonary orifice is separated from the right 
 auriculo-ventricular opening by the orifice of the aor a. 
 
 In examining these openings, we observe that the plane of the auriculo-ventricular or- 
 ifices is directed obliquely backward and downward : this explains the difference in the 
 heights of the ventricles before and behind. We also notice the reflection or turning in- 
 ward of the base of each ventricle (q a, p b) upon itself, so as to form a circular groove 
 or trench on the inner surface of its cavity, running entirely round the margin of the cor- 
 responding auriculo-ventricular orifice. 
 
 The Muscular Fibres of the Heart. 
 
 The Muscular Fibres of the Ventricles. 
 
 Dissection. — The muscular fibres of the heart may sometimes be traced without any 
 
 preparation ; but, generally speaking, either commencing putrefaction, maceration in 
 
 vinegar, or, still better, hardening and separation of the fibres by means of alcohol, and 
 
 especially by boiling, are necessary for this purpose. This being done, remove first the 
 
 * [The muscular fibres of the heart, though involuntary, very closely resemble in structure those of the 
 voluntary muscles (see note, p. 194), but the transverse striae upon them are less distinct. 
 
 The lining membranes of the two sides of the heart are covered by epithelium, and form what is termed 
 the endocardium.'] , 
 
 t I for a long time believed that the sigmoid valves, both the aortic and the pulmonary, were formed by 
 two prolongations of the internal membrane of the heart reflected upon itself ; but I have from pathological 
 facts lately the positive demonstration that each sigmoid valve was formed, 1st, by a prolongation of the in- 
 ternal membrane of the aorta ; 2d, by a prolongation of the internal membrane of the ventricle ; 3d, by an in- 
 termediate lamella occupying only the half of the height of the valve on the side of its adhering borde.i ; this 
 lamella is fibrous, and comes from the arterial zone. The half of the valve which is near the free border is 
 not furnished with this intermediate lamella. Now the arterial lamella may be affected independently of the 
 ventricular, and both Ijie arterial and ventricular lamellis may be injured independently of the intermediate 
 fibrous lamella which constitutes the foundation of these valves, since it gives them chiefly their power of re- 
 sistance. 
 
THE HEART. 489 
 
 oater membrane, and then the different muscular layers one by one, taking care to fol- 
 low the fibres from their origin to their termination. 
 
 The most general formula which can be given respecting the structure of the ventri- 
 cles is, that this portion of the heart is composed of two muscular sacs, co7itained within a 
 third, which is commjon to both ventricles. We should add, that, when the superficial or 
 common fibres arrive at the apex of the heart, they turn up so as to pass into the interi- 
 or of the ventricles at that point, and form the deep fibres of these two cavities, so that 
 the proper fibres of each ventricle are situated between the direct and the reflected por- 
 tion of the common fibres. 
 
 We shall now enter into some details regarding these fibres. 
 
 All the muscular fibres arise from the fibrous zones, and they all terminate upon them, 
 as was clearly pointed out by Lower.* They do not consist of short fibres placed end 
 to end, but are of considerable length, descending in one part of their course, and as- 
 cending in the other. The muscular fibres are ranged in successive layers, which pass, 
 as it were, into each other. The muscular fasciculi of each layer are not distinct from 
 one another, but they mutually send off fibres, by which they are bound together like the 
 pillars of the diaphragm ; or it may be said that they intersect each other at very acute 
 angles ; it is, therefore, impossible to calculate the number of layers, which, according 
 to Wolff, are about three in the right ventricle and six in the left. All that we are able 
 to determine is, the different sets of fibres which enter into the formation of the heart, 
 and of these we find that there are two sets, one common, the other _pro^er fibres. 
 
 The Superficial Common Fibres. — All the superficial fibres are common to the two ven- 
 tncles, and all are oblique and curved ; they commence at the base of the heart, and 
 pass obliquely, in a spiral manner, towards the apex. All the superficial fibres of the an- 
 terior region of the heart pass from the right to the left side ; all those of the posterior 
 region from the left to the right side. There are neither vertical nor horizontal fibres in 
 the heart, as some authors have stated. The arrangement of the fibres at the apex of 
 the heart forms, as it were, a key to the stnicture of the entire organ. The anterior 
 and the posterior superficial common fibres both converge towards that point. Each of 
 these sets of fibres forms a very distinct fasciculus or band, and the two bands mutually 
 turn round each other in a semi-spiral direction, so that the anterior band is embraced 
 on the left side by the posterior, which is, in its turn, embraced by the anterior band on 
 the right side ; from the apex of the heart the fibres change their course, and instead 
 of descending, they ascend ; and instead of being superficial, they become deep-seated. 
 Having entered the heart at its apex, they continue to be reflected upward, and present an 
 arrangement which I shall describe after having explained the course of the proper fibres. 
 
 The Proper Fibres. — ^These are situated between the superficial or descending, and the 
 deep or ascending portion of the common fibres. They form in each ventricle a sort of 
 small barrel or truncated cone, which is applied to that of the opposite ventricle ; the su- 
 perior openings of these cones correspond to the auriculo- ventricular orifices ; while the 
 inferior, which are smaller, leave opposite the apex of the heart two considerable inter- 
 vals, which are filled up by the common fibres. Do these proper fibres turn round and 
 round without end, hke an uninterrupted spiral, as Senac was inclined to believe 1 It 
 appears to me that their extremities are attached to the auriculo-ventricular zones, and 
 that they describe more or less complete circles, which intersect each other at very 
 acute angles. 
 
 The Reflected or Deep Common Fibres. — The superficial common fibres are reflected at 
 the apex of the heart, and penetrate into its interior through the lower orifices of the 
 small barrels or cones, formed by the proper fibres. In this situation the anterior and 
 posterior bands, by being reflected upward, and mutually turned round each other, form, 
 at the apex of the heart, a sort of star with curved rays. 
 
 Nothing can be more evident than the reflection or turning up of the fibres ; it was 
 pointed out, thougn vaguely, by Vesalius, but has been most explicitly described by Ste- 
 no, who stated expressly that the external fibres enter the heart at the apex, and, assu- 
 ming an opposite direction to their former one, become the innermost layers, and who 
 compared the apex of the heart to a star. It was also described by Lower, who has ac- 
 curately figured a radiated structure at the summit of each ventricle ; by Winslow, who 
 says that the superficial fibres enter the heart at its apex ; and by Wolff and Gerdy, who 
 state that the fibres of the heart are twisted into a whorl or vortex. 
 
 From the turning back and the lateral twisting of the anterior and posterior bands, it 
 follows that, by removing the serous membrane which covers the apex of the heart, we 
 may, without injuring the fibres, penetrate into its interior at two points, one to the 
 right, and the other to the left of the anterior band. 
 
 The deep reflected fibres having thus reached the interior of the ventricles, pass on 
 the inner side of the proper fibres, and are arranged in three perfectly different modes : 
 thus, some form simple loops with the superficial portion ; others are arranged like the 
 thread of a screw, or the figure 8. and others constitute the columnae carneae. 
 
 * The same arTangement occurs in regard to the fibres of the auricles ; it follows, therefore, that the nxii» 
 cular fibres of the ventricles are not directly continuous with those of the auricles. 
 
 Qqq 
 
490 ANGEIOLOGY. 
 
 The looped fibres, noticed by Winslow under the name of the bent or arched fibres, and 
 so well described by Gerdy, form, by their superficial and their deep portions, the opposite 
 walls of the ventricle : thus, the anterior superficial fibres constitute by their reflection 
 the deep layer of the posterior wall, while the posterior superficial fibres, after being re- 
 flected, form the deep layer of the anterior waU. 
 
 The fibres, arranged like the thread of a screw, or like the figure 8, with its lower ring ex- 
 tremely narrow, have been accurately described and even figured by Lower, and were 
 improperly rejected by Winslow, Senac, and others. The superficial portion of these 
 fibres exactly resembles that of the looped fibres, and are always twisted after their re- 
 flection, so that their deep portion belongs to the same wall as their superficial. Thus, 
 those fibres whose superficial portion belongs to the anterior wall of the ventricle, assist 
 in forming the same wall by their deep portion. 
 
 The columnce, carnea of the heart are formed by a certain number of fibres reflected in 
 loops, or like the figure 8. 
 
 Such is the arrangement of the muscular fibres of the ventricles.* 
 
 The Muscular Fibres of the Auricles. 
 
 The auricles, like the ventricles, have common and proper muscular fibres. There is only 
 one fasciculus of common fibres ; it occupies the anterior surface of both auricles, and 
 extends transversely from the right to the left auricula. The proper fibres constitute a 
 very thia muscular layer for each auricle ; they all commence and terminate at the cor- 
 responding ventricular zone. 
 
 The Proper Fibres of the Left Auricle. — The muscular layer in this auricle is continuous 
 and uniform, and not areolar. It consists of circular fibres, which occupy the neighbour- 
 hood of the auriculo- ventricular orifice, and all the anterior region of the auricle ; and of 
 oblique fibres, also arising from the auriculo-ventricular orifice, and divided into several 
 very distinct loops. One circular loop passes between the auricula and the left pulmo- 
 nary veins ; a second forms a vertical zone, interposed between the right and left pulmo- 
 nary veins ; it is very broad, and occupies the entire interval between the veins of the 
 right and left side ; a third and a fourth, very small, are interposed between the two pul- 
 monary veins of each side. These fasciculi, by changes in their direction, become adapt- 
 ed to the circular form of the orifices, and constitute true sphincters. It would appear 
 that, besides these bundles, there are some proper circular fibres around each orifice. 
 
 The Proper Fibres of the Right Auricle. — In the right auricle the fleshy fibres do not 
 form a continuous layer. This auricle may be regarded as consisting, in the first place, 
 of a non-muscular portion, which may be called the confluence of the vence cavce {sinus ve- 
 nosus) ; in it there is only one small muscular bundle, situated immediately to the right 
 of the orifice of the vena cava superior ; and, secondly, of a muscular portion, which re- 
 sembles a sort of grating, and is comprised between two fasciculi, one a circular bun- 
 dle, surrounding the auriculo-ventricular orifice ; the other a very prominent semilunar 
 bundle, interposed between the vena cava inferior and the auricula, and forming a ver- 
 tical, or, rather, an oblique arch, which terminates to the right of the inferior cava. 
 
 Muscular Fibres of the Auricula. — The walls of the left auricula present a cavernous 
 or areolar structure, in the middle of which we see a central canal, which opens into the 
 anterior of the auricle by a distinct orifice. There is not, in general, any central canal in 
 the right auricula, but only an areolar or cavernous structure. 
 
 The muscular fibres of the inter-auricular septum form a muscular ring for the border 
 of the fossa ovalis (so incorrectly termed the isthmus or annulus of Vieussens), which 
 must be regarded as a true sphincter, consisting of two thirds, three fourths, or even an 
 entire circle. The fibres of which it is formed arise from the auriculo-ventricular ori- 
 fice, near the septum. Some muscular fibres are often found in the substance of the floor 
 of the fossa ovalis. The other muscular fibres of the septum are continuous with the 
 circular fibres of the auricles. 
 
 Separation of the Two Hearts. 
 
 Dissection. — Divide the anterior fibres of the ventricles carefully, layer by layer, paral- 
 lel to the anterior furrow. Then separate the two ventricles, by means of the finger or 
 the handle of the scalpel. In order to separate the auricles, carry the scalpel along the 
 posterior inter-auricular furrow, being particularly careful upon arriving at the fossa ova- 
 lis. It is often possible to separate the auricles completely without opening either of them. 
 
 The division of the heart into the right and the left heart is not merely imaginary or 
 theoretical, but is capable of actual demonstration. After making the beautiful prepara- 
 tion described above, we find that the left convex ventricle is received into a correspond- 
 ing concavity in the right ventricle ; the two are therefore adapted to each other, and 
 
 * The arrangement described above is common to both ventricles. In the ri^ht ventricle almost all the re- 
 flected fibres enter into the columnve cameae. There is no interlacing, or indigitation of the fleshy fibres along 
 the anterior and posterior furrows, as has been stated ; still less do we find a raph6 in the situation of these 
 furrows. The splitting and separation of the muscular fibres, caused by the entrance of the bloodvessels oppo- 
 site the furrows, and the condensation of the fibres between the openings for the vessels, have occasioned thes« 
 •rroneous views. 
 
THE HEART. 4#1 
 
 their mutual reception is rendered complete by means of the infiindibuliform prolonga- 
 tion of the right ventricle. 
 
 On the other hand, the right auricle is convex, and is received into a corresponding 
 concavity in the left auricle. 
 
 By placing the two halves of the heart together, we see clearly the position of the aor- 
 tic opening behind and to the right side of the pulmonary, the crossing of the aorta and 
 the pulmonary artery in the form of the letter X ; the relation of the aorta with the base 
 of the right ventricle, and its situation between the right auriculo-ventricular orifice, 
 which is behind, and the infundibuliform prolongation of the right ventricle, which is in 
 front of it. This last relation explains how a communication may take place between 
 the aorta and the right ventricle. 
 
 The separation of the two sides of the heart also enables us to judge accurately of the 
 shape and the relative size of the two ventricles, the regular conical form of the left 
 ventricle, and the prismatic and triangular form of the right ventricle, the left wall of 
 which is, as it were, pushed inward by the corresponding projection of the left ventricle. 
 We can also ascertain the shape and relative size of the two auricles. 
 
 Vessels, JVerves, and Cellular Tissue. 
 
 Arteries. — The heart receives certain proper arteries, called cardiac or coronary, from 
 their being arranged in the form of a circle or crown. They are two in number, and are 
 the first branches given off by the aorta. They form two arterial circles placed at right 
 angles to each other ; that is to say, one circle follows the auriculo-ventricular furrow, 
 and the other occupies the inter- ventricular furrow. 
 
 Veins. — Corresponding to these two arteries there is one vein, named the great car- 
 diac or coronary vein, and a few small ones, called the anterior coronary veins. I do not 
 think that the existence of those accessory veins described by Thebesius as terminating 
 directly in the right auricle and the other cavities of the heart has been clearly demon- 
 strated. I have already said that the common openings of several groups of areolae have 
 been often mistaken for the orifices of veins. There is always an opening resembling 
 the orifice of a vein below the vena cava superior, but injection does not show any ves- 
 sel there. 
 
 Lymphatics. — These terminate in the numerous lymphatic glands which surround the 
 bronchi and the lower part of the trachea. 
 
 Nerves. — The cardiac nerves are small when compared with the nerves received by 
 other muscular organs, with those of the tongue, for example, and especially with those 
 of the muscles of the orbit. Some are derived from the cervical ganglia of the sympa- 
 thetic nerves, the others from the cerebro-spinal system, viz., the cardiac branches of 
 the pneumogastric. 
 
 These nerves, which are placed near the arteries, follow them at first, but soon sep- 
 arate from them, and are lost in the muscular substance. We cannot, therefore, admit 
 the opinion of Behrends, who attempted to prove that the nerves are intended only for 
 the vessels of the heart, and not for its proper tissue. 
 
 Cellular Tissue. — The serous cellular tissue which unites the muscular fasciculi of the 
 heart is so delicate, that it is extremely difficult to demonstrate it. In certain cases of 
 disease it may become loaded with fat. • 
 
 We always find a greater or less amount of fat upon the surface of the heart beneath 
 the serous membrane ; it abounds in the circular furrow between the auricles and ven- 
 tricles, in the furrow of the ventricles, at the apex and right border of the heart, in the 
 furrow between the pulmonary artery and the aorta, and between the small digital ap- 
 pendages upon the top of the left auricle. 
 
 ' Development. 
 
 In Size. — The heart is larger in proportion to the rest of the body in the earlier stages 
 of its development. 
 
 In the foetus, at the full term and after birth, the weight of the heart is to that of the 
 body as 1 to 120 ; before the end of the third month of intra-uterine life it is as 1 to 50. 
 It should be renoembered that, at the fourth or fifth week, the heart of the foetus occu- 
 pies the entire cavity of the thorax. In old age, the heart does not undergo atrophy like 
 most of the other organs ; and, in many subjects far advanced in years, it is even hyper- 
 trophied. 
 
 In Direction. — During the first three months the heart of the foetus is directed verti- 
 cally, as in other mammalia ; it does not begin to deviate to the left side and forward, as 
 in the adult, until the fourth month. 
 
 In Shape.* — The heart, at an early period, forms a rounded and symmetrical mass, of 
 which the auricles constitute the greatest part ; the ventricles appear at this time to be 
 only appendages of the heart, and the right auricle alone is equal in size to all the rest 
 of the organ. The ventricles are gradually enlarged, while the auricles diminish, and 
 towards the fifth month the due proportion between the auricles and ventricles is estab- 
 
 ■ "^ ^ * See note, p. 492. 
 
4^ ANGEIOLOGY. 
 
 lished ; the left ventricle is, at this period, more capacious than the right. The walls of 
 the heart are thicker than they are afterward, and the heart is firmer, and does not col- 
 lapse when empty. The thickness of the parietes of both ventricles is almost the same. 
 
 In Interned Conformation. — It is in reference to its internal structure that the principal 
 changes occur during the development of the heart. The right and left sides of the 
 heart communicate freely during the whole period of intra-uterine existence. The in- 
 ter-auricular septum does not exist, or, at least, only in a rudimentary state, during the 
 earlier months of foetal life. 
 
 Is there any period of fcetal existence during which the inter- ventricular septum is 
 entirely wanting 1 and does the development of the human heart, which would then re- 
 semble the heart of reptiles, coincide with the general law by which the organs of man, 
 before acquiring their perfect form, pass successively through the several conditions rep- 
 resented by the corresponding organs in the lower animals'! The observations of Meck- 
 el, which extend as far back as the fourth week, prove that the inter-ventricular septum 
 always exists at that period, but that it is imperfect at the upper part, where it is perfo 
 rated or notched.* 
 
 Cases of malformation, in which the septum of the ventricles is absent, cannot be quo 
 ted in support of the opinion that the septum is wanting in the early periods of life ; foi 
 it would be necessary to prove that such a malformation is an arrest of development. 
 
 The opening between the two auricles becomes contracted, and forms the foramen 
 ovale (or foramen ofBotal), which is found at the posterior and inferior part of the septum. 
 
 The valve of Eustachius is sufficiently broad to separate the orifice of the vena cava 
 inferior from the cavity of the right auricle, so that the blood of that vein is carried di- 
 rectly into the left auricle. 
 
 Towards the end of the third month, the valve of the foramen ovale, which afterward 
 forms the bottom of the fossa ovalis, begins to appear ; it arises from the posterior half 
 of the opening of the vena cava inferior. About the same period the Eustachian valve 
 decreases in size, and from this time the development of these two valves proceeds in- 
 versely, that is to say, the Eustachian valve diminishes, while that of the foramen ovale 
 becomes larger. In consequence of this change, the vena cava inferior no longer opens 
 into the left auricle, but into the right. 
 
 At the fifth month the foramen ovale is almost entirely closed by the valve which 
 grows from below upward, and from behind forward ; at a later period it projects into 
 the left auricle, beyond the margin of the foramen ovale, so that there is an oblique pas- 
 sage from one auricle to the other. After birth, adhesion takes place between these 
 parts ; but even when this does not occur, the obliquity of the passage is such, that the 
 want of adhesion does not necessarily allow of any admixture of the blood of the two 
 auricles. 
 
 Function. 
 
 The heart is the agent by which the blood is impelled tlirough the vessels. The ve- 
 nous blood is poured into the auricles, which then contract ; part of the blood flows back 
 into the veins, but the greater portion passes into the ventricles, which contract in their 
 turn. The auriculo- ventricular valves meet, and prevent the reflux of the blood into the 
 auricles, and it is, therefore, propelled intg the arteries. The sigmoid valves at first lie 
 in contact with the walls of the arteries, so as to permit the blood to pass from the ven- 
 tricles ; they then fall down at the moment when the distended arteries react upon their 
 contents, and thus prevent the reflux of the blood into the ventricles. The contraction 
 and dilatation of the heart have been termed its systole and its diastole. 
 
 The two auricles contract simultaneously ; so also do the two ventricles. The dila- 
 tation of the auricles occurs during the contraction of the ventricles, and vice versa. 
 Dilatation is not an active phenomenon, for the fibres of the heart are so arranged that 
 they can produce shortening and contraction of this organ, but can neither elongate nor 
 dilate it. 
 
 The spiral direction of the fibres of the heart induced the ancients to conjecture that 
 the contractions of the ventricles took place in a spiral fashion ; and, in the first edition 
 of this work, looking only at the anatomical arrangement, I said that this view of the 
 subject was not so devoid of foundation as at first sight it might be imagined. But, 
 
 * [The researches of modern emhryologists have shown that the heart, in its simplest condition, consists of 
 a straight tube, which is placed vertically in the body, receives the veins at its inferior extremity, and gives 
 off the arteries from its superior extremity. The lower or venous end soon turns upward, so that the tube be- 
 comes bent into a loop, which for a time projects through a cleft on the anterior aspect of the body. The tube 
 then becomes divided into an auricular and a ventricular portion, and into a bulbus arteriosus, all enclosed in 
 a pericardium; and in this state the heart of the human ftstus corresponds with the permanent condition of 
 this organ in fishes. Each of these three portions becomes again subdivided : the auricular portion by a de- 
 scending septum into the two auricles, the ventricular by an ascending septum into the two ventricles, and 
 the bulbus arteriosus into the aorta and pulmonary artery. For a certain period, the right and left auricles 
 and the right and left ventricles communicate with each other. When the septum between the ventricles ii 
 yet imperfect (a condition which is permanent in reptiles generally), the common ventricular cavity gives ori- 
 gin to both the aorta and the pulmonary artery. Before the middle of fcetal life this septum is completed, and 
 then the two vessels arise each separately from its proper ventricle. The septum between the auricles re- 
 mains imperfect until after birth, when the foramen ovale at length becomes closed.] 
 
THE HEART. 
 
 from the opportunities I have lately had of observing the movements of the heart in a 
 new-born child, full of life and vigour, whose heart, deprived of the pericardium, had 
 passed entirely outside of the chest, through a circular perforation in the upper part of 
 the sternum, I have been enabled to establish the following facts in reference to this in- 
 teresting subject (see Gazette de Paris, August 7th, 1841) : 
 
 First, the contraction of the right ventricle and the contraction of the left ventricle 
 are simultaneous, or synchronous ; this is also the case with the contraction of the au- 
 ricles. 
 
 Second, the contraction of the ventricles coincides with the dilatation of the auricles 
 and the projection of the blood into the arteries. The dilatation of the ventricles coin- 
 cides with the contraction of the auricles and that of the arteries. 
 
 Third, there are but two conditions in the movements of the heart : those of its con- 
 tractions and those of its dilatations ; the state of rest which is spoken of by authors is 
 completely wanting. Dilatation is immediately followed by contraction, and contraction 
 by dilatation. 
 
 Fourth, in observing the heart in the case referred to, the question about the order of 
 succession in the movements of the heart, viz., whether the contraction of the auricles 
 precedes that of the ventricles, as most observers assert, or whether the contraction of 
 the ventricles precedes that of the auricles, is found to have no foundation to rest on : 
 it seems that the contraction and the dilatation of the ventricles and that of the auricles 
 result from two opposite forces, continually active, which alternately, and, as it were, 
 necessarily conquer each other in an invariable order, in the fashion of the two alternate 
 movements of a pendulum, or a perfectly-balanced balance-pole. 
 
 Fifth, the duration of the contraction of the ventricles continues twice as long as that 
 of their dilatation. On dividing into three equal periods the whole duration of the sys- 
 tole and diastole of the ventricles, we will have two for the contraction and one for the 
 dilatation. The period of repose mentioned by authors has been taken from the first 
 period of the contraction. In regard to the auricles, on dividing into three equal parts 
 the whole duration of their contraction and dilatation, we wiU have two for dilatation 
 and one for contraction. 
 
 Sixth, during the time of their contraction or systole, the ventricles grow pale, their 
 surface becomes rugged, strongly folded, and, as it were, shrivelled. The superficial 
 veins swell ; the columnse carneae of the ventricles are marked off; the twisted fibres 
 of the summit of the left ventricle, which of itself constitutes the apex of the heart, be- 
 come more manifest. 
 
 Seventh, during their contraction the ventricles contract in all their diameters ; and 
 if the phenomenon of their shortening is the most sensible, this is attributable to the 
 greater dimension of the vertical diameter. During the systole of the ventricles, the 
 summit of the left ventricle, or, what is the same, the summit of the heart, describes a 
 spiral movement from right to left and from behind forward. 
 
 Eighth, it is this spiral contraction, which is slow, gradual, and successive, as it 
 were, which produces the movement forward of the summit of the heart, and, conse- 
 quently, the striking of the apex against the walls of the thorax. The systole of the 
 ventricles is not accompanied, as I had before beheved, with a movement of projection 
 of the heart forward : it is the spiral contraction which determines exclusively the ap- 
 proximation to, and even the striking of the apex of the heart against the walls of the 
 thorax. 
 
 Ninth, the dilatation or diastole of the ventricles takes place in a sudden, instanta- 
 neous manner : at first sight one would say that it constituted the active movement of 
 the heart, it is so rapid and energetic. No one can have any idea, without having ex- 
 perienced it, of the force with which the dilatation overcomes pressure made upon this 
 organ. The hand which firmly grasps the heart is forcibly opened by its diastole. 
 
 Tenth, the dilatation or diastole of the ventricles is accompanied with a movement 
 of projection of the heart downward. This movement of projection was carried to its 
 maximum when the child was placed in the vertical position ; it was so marked, that at 
 first I was induced to believe that it was during the diastole of the ventricles that the 
 percussion of the heart against the walls of the thorax took place. This idea I still en- 
 tertained, rom an experiment which I had made at a former period upon the hearts of 
 frogs ; but a more accurate examination of the phenomenon has shown me that it was, 
 indeed, during the systole of the ventricles, and towards the end of this systole, that the 
 percussion of the apex of the heart against the walls of the thorax took place. 
 
 Eleventh, the dilatation of the auricles takes place as suddenly as the dilatation of the 
 ventricles, but it lasts as long as the systole of the ventricles : the contraction of the auri- 
 cles, on the contrary, lasts no longer than the diastole of the ventricles. 
 
 Twelfth, during its dilatation, the right auricle seems on the point of bursting, so 
 great is its distension and so thin are its walls. The left auricle, which is narrower, 
 more elongated, and thicker, does not exhibit the same phenomenon, at least not in the 
 same degree. I have not been able to judge of what takes place in the auricular pro- 
 cesses except from the movements of the auricles. 
 
494 ANGEIOLOGY. 
 
 In regard to the sounds of the heart, it results, from the experiments which I have 
 made upon the heart of this child {Medical Gazette, loco citato), that the two sounds of 
 the heart have their seat at the origin of the pulmonary and aortic arteries, and that 
 they originate in the clashing of the sigmoid valves ; that the first sound, which coin- 
 cides with the systole of the ventricles and the dilatation of the arteries, results from 
 the rising of the sigmoid valves, which were previously lowered ; that the second sound, 
 which coincides with the diastole of the ventricles and with the contraction of the ar- 
 teries, results from the lowering of the sigmoid valves pressed down again by the gush 
 of the returning blood. The simplicity of this theory, the easy and natureil explanation 
 which it affords of all the facts that have come to my knowledge, may, perhaps, be con- 
 sidered as a proof of its truth. 
 
 THE PERICARDIUM. 
 
 The pericardium {pp,fig- 170) is a fibro-serous sac, which surrounds and protects the 
 heart. 
 
 Congenital absence of the pericardium is extremely rare ; complete adhesion of the 
 pericardium to the heart, or cellular transformation of this membrane, have been most 
 commonly mistaken for such malformation. Nevertheless, I have seen the heart of an 
 adult to which there was no pericardium : this anomaly has been figured by M. Breschet. 
 The heart was free from any adhesion, and occupied the cavity of the left pleura. 
 
 The older anatomists, and particularly Senac, attempted to determine exactly how 
 much larger the cavity of the pericardium is than the heart. Having injected water into 
 the pericardium in different subjects, this observer found that the quantity of liquid con- 
 tained between the heart and its covering varied from six to twenty-four ounces. I have 
 satisfied myself that in the healthy state, the capacity of the pericardium exactly corre- 
 sponds to the size of the heart when that organ is dilated to the utmost. In certain 
 cases of hydrops pericardii, this sac becomes enormously enlarged ; on the other hand, 
 its inextensibility explains the syncope which immediately follows rupture of the heart,* 
 and which is produced by the accumulation of a small quantity of blood in the pericar- 
 dium. The syncope which accompanies the effusion from acute pericarditis probably 
 depends upon a similar cause. 
 
 Form. — The pericardium is shaped like a cone, with its base downward and its apex 
 upward. It has an external and an internal surface. 
 
 External Surface. — The pericardium is situated in the mediastinum, and has the fol- 
 lowing relations : 
 
 In front it corresponds to the sternum and the cartilages of the fifth, sixth, and seventh 
 ribs on the left side, from which it is separated by the pleura and the lungs ; in the mid- 
 dle it is separated from the sternum by some cellular tissue only. The pericardium is 
 in more or less immediate relation with the sternum, according to the size of the heart, 
 or the quantity of fluid in the pericardium. Behind, it corresponds to the vertebral col- 
 umn, from which it is separated by the posterior mediastinum and the organs contained 
 in it, viz., the oesophagus, the aorta, the thoracic duct, &c. On the sides, it is in imme- 
 diate relation with the pleurae, and indirectly with the lungs. The phrenic nerves and 
 the superior phrenic arteries are applied along the sides of the pericardium. The base 
 corresponds to the cordiform tendon of the diaphragm, and to the muscular fibres on the 
 left side of it. It adheres closely to the diaphragm only in the anterior half of its cir- 
 cumference ; in every other part the base of the pericardium may be easily detached. 
 The apex is prolonged upon the great vessels which enter and pass out at the base of 
 the heart. 
 
 The pericardium is covered by the pleurae in the greatest part of its extent, and is 
 united to them by cellular tissue, which is tolerably dense at the sides, and very abun- 
 dant in front and behind. The cellular tissue of the anterior mediastinum is often load- 
 ed with fat, as well as that which surrounds the base of the pericardium, where it 
 sometimes forms prolongations resembling the appendices epiploicas upon the large in- 
 testine. 
 
 The internal surface of the pericardiimi is free and lubricated by serosity, like the inner 
 surface of allfserous cavities. t 
 
 Structure. — The pericardium is a fibro-serous membrane analogous to the dura mater, 
 and, like it, is composed of two very distinct layers, one externd and fibrous, the other 
 internal and serous. 
 
 The fibrous layer consists of fasciculi mterlacing in all directions. It is extremely 
 thin, and from its adhesions to the cordiform tendon of the diaphragm, it has been re- 
 garded as a prolongation of that structure, but it adheres closely to the diaphragm only 
 
 * Death from rupture of the heart is not produced by hemorrhag'e, for often we do not find more than seven 
 or eight ounces of blood escaped ; but it is caused by compression of the heart, in consequence of the inexten- 
 sibility of the pericardium. 
 
 t On opening the thorax of dead bodies, the internal surface of the pericardium is, as it were, dried up ; 
 this drying up is owing to the air contained in the lungs. 
 
THE ARTERIES. 495 
 
 in front, and much less intimately in the foetus and the new-bom infant. In conse- 
 quence of this adhesion, the pericardium follows all the motions of the diaphragm. 
 
 The fibrous layer is prolonged upon the surface of the great vessels which open into 
 the cavities of the heart, and furnishes for each of them an indistinct sheath, which is 
 soon lost upon them. 
 
 The scratis layer of the pericardium, like the serous membranes generally, forms a shut 
 sac, adherent by its outer surface, but free and smooth internally.* After having lined 
 the fibrous layer, it is reflected upon the great vessels at the base of the heart, and then 
 covers the heart itself, of which it forms the external membrane. We shall consider it 
 as consisting of a parietal, and a visceral or reflected portion. 
 
 The Parietal Portion. — The fibrous and the serous layer of the pericardium are so 
 closely adherent, that it is very difficult to separate them. We shall find the same to be 
 the case with the dura mater. 
 
 The Reflected w Visceral Portion. — The existence of this portion of the serous mem- 
 brane can be shown most readily at the points where it is reflected from the fibrous mem- 
 brane upon the great vessels. It forms one complete sheath, which is coirunon to the 
 aorta and pulmonary artery ; some fat is often found in the furrow between these two 
 vessels ; it also forms two semi-sheaths for the venae cavae and the four pulmonary veins, 
 which are thereby rendered smooth only in the anterior half of their circumference. The 
 heart is entirely covered by the serous membrane, which is here extremely thin. In fat 
 hearts it is raised from the muscular fibres by some flakes of adipose tissue, like the ap- 
 pendices epiploicae of the great intestine. 
 
 Vessels and Nerves. — The arteries of the pericardium are very small ; they are derived 
 from the surrounding arterial branches, viz., the superior phrenic, the anterior mediasti- 
 nal, and the bronchial. The veins accompany the arteries, and open into the brachio- 
 cephalic veins. Several of them are also said to terminate in the coronary veins. The 
 lymphatic vessels enter the lymphatic glands, which surround the vena cava superior. 
 
 No nerves have yet been demonstrated in the pericardium, though possibly they may 
 exist. 
 
 THE ARTERIES. 
 
 Definition. — Nomenclature. — Origin. — Varieties. — Course. — Anastomoses. — Form and Re- 
 lation. — Termination. — Structure. — Preparation. 
 
 The term arteriesf is applied to the vessels which arise from the ventricles of the 
 heart, and to their several divisions. 
 
 There are two systems of arteries, one of which commences at the right ventricle, 
 while the other commences at the left. The primitive trunk of the first is the pulmona- 
 ry artery, that of the second is the aorta. 
 
 These two arterial systems are perfectly distinct in the adult, but communicate fi-eely, 
 and form only one system in the foetus. 
 
 The following general remarks apply more particularly to the aorta and its divisions : 
 
 The arteries form an uninterrupted succession of decreasing canals, all arising from a 
 common trunk. In this respect we may compare the entire arterial system to a tree, the 
 trunk of which is the aorta, while the larger and smaller branches and the twigs are rep- 
 re^sented by the divisions which arise in succession from that vessel, as from their com- 
 mon origin. 
 
 Again, since the total area or capacity of all the arterial divisions greatly exceeds that 
 of the aorta, we may also regard the arterial system as a cone, the base of which is sit- 
 uated in the entire body, and the apex at the aorta.t 
 
 The study of the arteries includes that of their nomenclature, origin, course, direction, 
 relations, anastomoses, termination, and structure. 
 
 Nomenclature. 
 
 The nomenclature of the arteries leaves little to be desired in regard to precision ; the 
 names of these vessels are derived either from those of the parts to which they are dis- 
 tributed, as the thyroid, lingual, and pharyngeal arteries, &c. ; or from their situation, as 
 the femoral and radial arteries ; or from their direction, as the circumflex and coronary 
 arteries. ' 
 
 The limits by which one artery is distinguished from another immediately succeeding 
 to it, may be either natural or artificial. 
 
 We may regard as natural limits the point of origin on the one hand, the point of divis- 
 ion on the other, as in the common iliac and conmion carotid arteries. 
 
 * Its inner surface is covered with epithelium. 
 
 t From anp, air, and Trjpclv, to keep. The etymology of this term affords us evidence of the error of the 
 ancients, who, because they always found these vessels empty and patent after death, imagined that they con- 
 tained air during life. 
 
 X Haller has collected all the comparative estimates that have been made between the area of the priacipa] 
 trunks and that of their respective divisions collectively. — {Elem. Phys., t. i., p. 151-163.) 
 
406 ANGEIOLOGY. 
 
 The object oi artificial limits is to enable us to establish certain divisions of the same 
 arterial trunk, by which means we can describe its relations with greater accuracy. 
 Thus we shall find successive portions of the artery of the upper extremity named the 
 subclavian, the axillary, and the brachial artery. 
 
 Origin of the Arteries. 
 
 The common origin* of the arterial system is the aorta, which arises from the left ven- 
 tricle of the heart in the manner already indicated (see The Heart) ;t but the origins of 
 the other arteries take place according to certain very general laws : thus, two arteries 
 of equal size may arise from the extremity of a larger artery, and appear to result from 
 the bifurcation of that vessel ; arteries arising in this manner might be called terminal 
 arteries. Other arteries arise from some point in the circumference of a larger vessel ; 
 these may be termed collateral arteries. 
 
 The terminal arteries almost always arise so as to form a bifurcation at an acute an- 
 gle ; the dichotomous division or bifurcation is the most common mode of division. The 
 acute angle is evidently favourable to the passage of the blood, which, in the first place, 
 maintains nearly the primitive direction in which it was impelled, and, secondly, is easi- 
 ly divided into two columns by the projecting crest at the angle of division. 
 
 The collateral arteries very often arise at an acute angle, but sometimes at a right, or 
 even at an obtuse angle. The two latter modes, especially the last, are unfavourable to 
 the flow of the blood. It must, however, be remarked, that many of the arteries which 
 follow a retrograde course in reference to the trunk from which they are derived, never- 
 theless arise at an acute angle. The caliber of the terminal arteries is very nearly pro- 
 portional to that of the artery from which they are given oft", but the collateral arteries 
 bear no proportion to the caliber of their trunks. We shall see a remarkable example 
 of this in the spermatic arteries, as compared with the aorta from which they arise. 
 
 It should also be observed, that the caliber of a principal trunk does not diminish in 
 proportion to the branches which it supplies : in proof of this, observe the aorta as it en- 
 ters the abdomen, and just before its division into the common iliac. 
 
 Anatomical Varieties of the Arteries. 
 
 No system of organs is more subject to anatomical varieties than the arteries. These 
 varieties sometimes affect their origin only, sometimes their course, but hardly ever 
 their termination.^ The study of these varieties is of great importance in surgery, both 
 in reference to the ligature of arteries, and also to operations performed in their vicinity.^ 
 
 Course of the Arteries. 
 
 The principal arteries generally follow the direction of the axis of the limbs. The sec- 
 ondary, tertiary, and farther divisions pursue the most varied courses, subject to no par- 
 ticular rule. 
 
 The principal arteries are usually straight ; but they present slight curves, which ren- 
 der the artery longer than the corresponding limb, and hence tend to prevent laceration 
 during the movement of extension, when the curves merely become obliterated and the 
 vessel undergoes no injurious stretching. The use of these curves in the arteries may 
 be proved by comparing the opposite conditions of the vessels during extension and flex- 
 ion of the upper and lower extremities. 
 
 A great number of the arteries pursue a very distinctly tortuous course, which, as 
 Haller remarks, is preserved by the surrounding cellular tissue, and which is connected 
 with certain particular conditions of the organs to which they are distributed. Thus, 
 we meet with very tortuous arteries in parts which are alternately subject to considera- 
 ble dilatation and contraction ; as, for example, the coronary arteries of the heart and 
 of the lips. 
 
 Again, the serpentine course of an artery, by increasing its length in a given space, 
 adds to the extent of surface from which collateral branches may arise. The curvatures 
 of the internal maxillary and of the ophthalmic arteries evidently have this advantage ; 
 and it is highly probable that the arch of the aorta may serve a similar purpose. 
 
 The arteries are tortuous in certain parts also, in which this arrangement would seem 
 to diminish the force and rapidity of the current of blood ; it cannot fail to be perceived 
 
 * The word origin must not be taken here in its exactly literal sense, for it has by no means been shown that 
 the arteries are developed from the heart towards the extremities. A very ingenious theory tends, on the con- 
 trary, to prove that development proceeds from the extremities towards the heart. 
 
 t I should add that the proper tissue of the aorta only touches the fibrous arterial zone opposite the angle, 
 or at the summit of the three festoons which the origin of the aorta exhibits. The arterial zone may be con- 
 sidered as the tangent of the three festoons. 
 
 t While the origin of the nerves exercises a great influence on their functions, the place from whence the 
 arteries originate appears to be of but little consequence, and is, at all events, very secondary. We cannot 
 agree in the opinion of Walther, that the origin of the arteries of an organ are intimately connected with the 
 mode of its existence, and with the functions which it performs. 
 
 ^ [For special information on the varieties in the distribution of the arteries, the reader is referred to Hal- 
 ler, Icones Anatomicce, 1756; Murray, Descriptio Arteriarum, &c., 1783-98; Barclay, Description of the Ar- 
 teries, <fec., 1818 ; Tiedemann, Tabula; Arteriarum, &c., !822 ; and to R. Quain's Anatomy of the Arteries, &c., 
 with drawings by J. Maclise, 1840, 1841.1 
 
THE ARTERIES. 497 
 
 that such is the intention of the curvatures described by the internal carotid and the 
 vertebral arteries. Bichat, it is true, has objected to this, that, in a system of commu- 
 nicating and permanently distended canals, the curvature can have no influence upon 
 the rapidity of the fluid circulating through them. But I would answer, that this prin- 
 ciple, though true in reference to a system of inextensible tubes, is not so when applied 
 to a system of dilatable canals like the arteries. In the latter case, in fact, part of the 
 momentum acts against the curvature itself, and straightens it in a certain degree, and 
 in this way there is a loss of some portion of the original momentum. 
 
 In some arteries this tortuous condition is acquired, in others it results from the prog- 
 ress of age. It proceeds from elongation of tne arteries, which is itself produced in the 
 following manner : At each ventricular systole, the arteries tend to become elongated 
 a« well as dilated. In the aged, and especially in those whose heart is very powerful, 
 this tendency to become elongated produces an actual and permanent elongation, as 
 may be seen in the abdominal aorta and in the conunon iliac, the humeral, and the radial 
 arteries, which, in almost aU old subjects, present alternate curvatures, that are never 
 met with in the infant and the adult. It has been incorrectly stated, that at each sys- 
 tole of the heart the curves were diminished, or manifested a tendency to be dimin- 
 ished : on the contrary, the curves increase. This increase of curve is evidently per- 
 ceived in observing the tempered artery during the systole of the ventricles. If an ar- 
 tery is injected, its branches, at each stroke of the piston, become more flexuous. If 
 the arteries were straightened, the dilatations and the calcareous deposites would not be 
 constantly observed on the side of the convexity of the curves. 
 
 Let us remark, that the dilatation of the arteries is, just as much ^ls their elongation, 
 a cause of the increase of their flexuosity. 
 
 The flexuosities of the arteries are of a twofold order, zigzag and spiral. The former 
 are more frequent ; the latter are especially noticed in the ovarian or testicular, uterine, 
 and sometimes facial arteries. 
 
 We may also consider as acquired the tortuous condition assumed by collateral arte- 
 rial branches, after the obliteration of the main trunk.* 
 
 Anastomoses of the Arteries. 
 
 During their course, the arteries communicate with each other by certain branches, 
 which sometimes unite two different trunks, and sometimes form a connexion between 
 two parts of the same trunk. This mode of communication is called anastomosis {ava, 
 by. and arofia, a mouth). There are several kinds of anastomoses. 
 
 Anastomosis by inosculation, or by loops, in which two vessels running in opposite di- 
 rections open into each other by their extremities and form a loop. 
 
 Attastomosis by transverse communication, as when two parallel trunks are united by 
 means of a branch at right angles to their own direction : for example, the anterior com- 
 municating artery of the brain. 
 
 Anastomosis by convergence, in which two arterial branches unite at an acute angle to 
 form a larger artery, as in the union of the vertebral arteries to form the basilar trunk. 
 
 By means of the anastomosis by inosculation or by loops, which is the most common 
 method of communication, uninterrupted collateral channels are established along the 
 great arterial trunks, the place of which they may even supply. The existence of these 
 anastomoses, and the power possessed by arteries of becoming enlarged to an almost 
 indefinite extent, originated the bold idea of attempting to tie even the largest arte- 
 rial trunks. 
 
 Anastomoses by inosculation are sometimes useful in regulating the distribution of 
 blood,+ and spreading out the origins of arteries over a more extended space. Thus, by 
 means of several series of arches, the superior mesenteric artery gives off branches which 
 proceed at right angles to the small intestine throughout its whole length. 
 
 Forms and Relations. 
 
 The arteries represent regular cylinders when they give off no branch, and cones, or, 
 rather, a series of decreasing cylinders, when they gradually diminish by giving off a 
 certain number of branches. Their cylindrical form, together with the looseness of the 
 surrounding cellular tissue, preserves them from a number of accidents. Thus, the hu- 
 meral and the femoral arteries glide over the head of the humerus and femur in disloca- 
 tions of these bones ; and so the carotid arteries, contrary to all apparent probability, 
 sometimes escape uninjured in incised wounds of the neck. 
 
 The arteries have relations with many other parts. With the bones, being supported 
 by them, and more 'or less closely approximated to them. Thus, the aorta is applied to 
 the vertebral column, and the arteries of the limbs, after escaping from the trunk, become 
 
 * There are flexuosities originating in malformation, by deviation or by fracture. In a case of fracture of 
 the neck of the femur, the femoral artery described very marked inflections at the hip. This was also the case 
 in a luxation of the femur with considerable shortening. The aorta becomes very flexuous in cases cf hunch 
 backs. 
 
 t [The retia mirabilia of arterial vessels, found in some animals, are examples of the repeated subdmsioD, 
 and anastomosis of arteries.] 
 
 R R R 
 
498 ANGEIOLOGY. 
 
 ^pliea to the corresponding bones, their course along which is marked by a depression 
 and against which they may easily be compressed (see Osteology). 
 
 From the relations of the arteries with the articulations, some important practical in- 
 ferences are derived. The arteries always occupy the aspect of flexion ; and as flexion 
 is performed in the larger articulations of a limb alternately in opposite directions, the 
 arteries are observed to alter their relative position, as it were, to regain the aspect ot 
 flexion. This is seen in the femoral artery as it becomes popliteal, and also in the 
 brachial, which at first lies in the cavity of the axilla, and then turns forward at the 
 bend of the elbow. In consequence of this arrangement, the arteries are protected by 
 the habitual, and, as it were, instinctive, position of the Umbs. 
 
 On the other hand, the proximity of certain arteries to articulations, and the absence 
 of any curvatures in such situations, may explain the occurrence of rupture of these 
 vessels in dislocation, and often, also, in immoderate attempts at reduction. 
 
 With the Muscles. — The muscles are the essential protectors of the arteries, which 
 they separate from the skin. There are large cellular spaces in the centre of the limbs 
 for the reception of the principal arteries, which are thus removed from the influence of 
 external violence. 
 
 Most arteries have a special muscle, which may be termed their satellite muscle. Thus, 
 the sartorius is the satellite muscle of the femoral artery ; the sterno-cleido-mastoideus 
 of the common carotid ; the biceps of the brachial artery, &c. 
 
 With the Skin. — Some arteries are sub-cutaneous, or, rather, sub-aponeurotic, in a 
 certain part of their extent ; and in large arteries, this is almost always at the point 
 where they emerge from the trunk, as in the femoral artery. The arteries of the cra- 
 nium are situated between the skin and the epicranial aponeurosis in the whole of their 
 extent. The importance of these relations in reference to compression of the vessels 
 may be easily conceived. 
 
 With the Veins. — The arteries are always in relation with certain veins, which are ap- 
 plied to them. When there are two satellite veins {vence comites) for one artery, the lat- 
 ter vessel is constantly placed between the two veins. 
 
 With the Nerves. — ^The arteries support the plexuses of nerves distributed to the or- 
 gans of nutritive life. We may even regard their plexuses as forming an accessory coat 
 to this set of vessels. Other nerves, though not so immediately in contact with the ar- 
 teries, have a constant relation with them. This it is of importance to know, so that 
 the nerves may be avoided, or that they may direct the operator in applying a ligature to 
 the vessels themselves. For each artery it may be said there is one satellite nerve. 
 
 With the Aponeurotic Sheaths. — ^The principal artery of a limb is provided with a fibrous 
 sheath, which belongs to it in common with its veins, and often with its accompanying 
 nerve. When an artery perforates a muscle, it is protected in its passage by a sheath 
 or aponeurotic arch, which prevents, or at least moderates, the compression during the 
 contraction of the muscle. 
 
 Lastly, the arteries are surrounded by a loose cellular sheath, which allows of their 
 dilatation and their alterations in position. The looseness of this cellular tisssue favours 
 the displacement of arteries during the infliction of wounds, and enables us to isolate 
 these vessels by blunt instruments, which cannot injure them.* As the nutritious ves- 
 sels reach the coat of the arteries through this sheath, we can easily understand the im- 
 propriety of separating the vessel from it too extensively in tying the arteries, t 
 
 Termination of the Arteries. 
 
 The divisions of the arteries are not so numerous as would at first sight appear. The 
 number of successive divisions, commencing at the aorta, is not more than twenty. 
 
 The arteries terminate in the substance of organs. The number of arteries distrib- 
 uted to each organ is in proportion to the activity of its functions ; secreting organs are 
 much more plentifully supplied with vessels than those in which the function of nutri- 
 tion only is performed. Soemmering, Prochaska, and others, have observed that the 
 actual termination of the arteries is different in different organs. Referring for farther 
 details upon this subject to textural anatomy, I shall content myself with stating here, 
 1st, that the arteries terminate in the capillary system, through the medium of which 
 they become continuous with the veins, as is demonstrated even by the coarsest in- 
 jections ; 2d, that the arteries enter only in a very slight degree into the composition 
 of the capillary system, which is essentially venous ; this may be ascertained by in- 
 jecting the arteries of an organ, the venous capillary system of the same having been 
 previously injected by the veins ; it will then be perceived that the arteries enter but 
 very little into the formation of the capillary system, and that they cease to exist as 
 soon as they have communicated with it. If it were objected that, through this prep- 
 aration, the injected liquid might have passed over from the venous capillary system into 
 
 * [Another ii^portant result of this is, that a divided artery is enabled to retract within its sheath. In the 
 abdomen and head this slieath scarcely exists.] 
 
 t I have seen a ligature of the primitive carotid which had been laid b»re to too great an extent followed 
 by a consecutive hemorrhage and death. 
 
A 
 
 V. 
 
 \ THE ARTERIES. 4^ 
 
 ffie arterial, I would remark, that the impossibility of this reflux is one of the most clear- 
 ly demonstrated facts in anatomy. 
 
 Structure of Arteries. 
 
 The walls of an artery are composed of three coats : an external, a middle, and an in- 
 ternal.* 
 
 The External Coat. — This is generally called the cellular coat, because it is in some 
 measure continuous with the surrounding cellular tissue. Scarpa erroneously regarded 
 it as not forming an integrant part of the arteries. It consists of a filamentous, areolar, 
 and, as it were, felted tissue, which is never charged with fat or infiltrated with se- 
 rum, and which appears to me to present all the characters of the dartoid tissue. I 
 believe that the contractility which has been attributed to the middle coat is altogether 
 dependant upon this.t It is the only coat which remains undivided after the appUca- 
 tion of a ligature. 
 
 The Proper or Middle Coat. — The characteristic properties of arteries are chiefly de- 
 pendant upon this coat. It is composed of circular fibres, which interlace at very acute 
 angles, but which do not present the spiral arrangement admitted by some authors. From 
 its yellow colour and its elasticity, it has been called the yellow or elastic coat. It is ex- 
 tensible longitudinally and transversely. It is very fragile, is easily torn by longitudinal 
 extension, and is cut by a ligature. It is proportionally thinner in the great than in the 
 small arteries. This coat is of the same nature as the yellow elastic ligaments, and is 
 therefore not muscular. Moreover, chemical analysis shows that it contains no fibrine ; 
 direct irritation develops no contractility in it ; and the supposed phenomena of irrita- 
 bihty pointed out by Haller may be entirely attributed to elasticity. It should be re- 
 marked that the middle coat may be separated in several distinct layers, which are, how- 
 ever, not independent of each other ; while the most external layers present a strongly- 
 marked fibrous linear disposition, the most internal exliibit an equally marked lamellar 
 one ; indeed, to such extent, that authors have considered as a dependance of the inter- 
 nal coat the layer of yellow tissue which is in contact with the internal membrane, 
 properly so called. 
 
 The Internal Coat. — It is a transparent pellicle of extreme tenuity ; it must be care- 
 fully distinguished from the subjacent layer, which is almost always dissected off with 
 it. It is of a pale pink colour, and is lubricated with serosity. It appears to be of the 
 nature of serous membranes, of which it presents the chief characteristics, viz., tenuity 
 and non- vascularity. t It may even be said that, like the serous membranes, it is ex- 
 clusively formed by a lymphatic net. I do not think that this internal coat of the arter- 
 ies, which may have been considered as a sort of inorganic glue, is extensible or elas- 
 tic ; on the contrary, in arteries in a non-distended state, this coat exhibits the appear- 
 ance of folds which disappear by distension. 
 
 Vessels and Nerves. — The arteries and veins distributed to the coats of the arteries are 
 called vasa vasorum. In regard to the question whether the arteries receive any nerves, 
 or whether the nervous plexuses which accompany them are only intended for the or- 
 gan to which the vessels are distributed, I would observe, that it has appeared to me 
 that several filaments of the great sympathetic nerve were lost in the thickness of the 
 aorta, and it is probable that the same disposition exists in regard to the less consid- 
 erable arteries. As to the vasa vasorum, some believe they arise from the neighbour- 
 ing vessels, while others are of opinion that they are derived from the vessels them- 
 selves to which they belong. I adopt the latter opinion, and believe that they mostly 
 arise from the arteries to which they are attached. The venous vasa vasorum of the 
 arterial coats join the nearest veins. 
 
 Preparation. 
 The preparation of an artery consists in separating it from the neighbouring parts, at 
 the same time preserving its relations. Most of the arteries may be studied without 
 any other preparation than a careful dissection ; but injections are necessary in order to 
 follow the smaller branches. The most convenient injection with which I am acquaint- 
 ed is the following :^ Tallow, nine parts ; Venice turpentine, one part ; ivory black, mix 
 ed with spirits of turpentine or varnish, two parts. 
 
 * All the vessels, and all the tubes of the body, are formed of different layers. 
 
 t All experimenters have observed that, in an animal which dies of hemorrhage, the arteries, during the 
 last moments of its life, lose a considerable part of their caliber, -which is restored to them immediately after 
 death. This phenomenon, which appears at first sight to be in opposition to the absence of the contractility, 
 properly so called, of the middle coat, may be easily accounted for by the tonic contractility of the dartoid 
 tissue. The presence of this tissue may also account for the smallness or the contraction of the pulse, in op- 
 position with its fulness, a double character which is sometimes met in the same individual, and in the same 
 diseases, at short intervals. 
 
 t [It consists of longitudinal fibres, which are slightly interlaced, and are covered with a squamous epithe- 
 lium. The longitudinal wrinkles observed in arteries contracted after death are produced in this coat.] 
 
 6 [The paint or cold injection is one of the most useful ; it consists of either red or white lead, mixed a» a 
 paint, with a small quantity of boiled linseed oil, with spirits of turpentine, and also with some driers, viz., 
 sugar of lead and litharge.J , 
 
500 ~^' ANGEIOLOGY. 
 
 The best injection for preparations intended to be preserved is wax, one part ; tallow, 
 three parts ; vermilion, indigo, or Prussian blue, first mixed with spirits of turpentine. 
 
 It is advantageous, before making the general injection, to throw in some turpentine 
 or spirit varnish, coloured with the substances mentioned above. 
 
 For a very fine injection it is necessary to use glue-size, coloured either Avith lamp- 
 black or vermilion ; but this mode of injection is not suitable where the preparation is to 
 be preserved. 
 
 In order to place a tube in the aorta, saw through the sternum longitudinally ; keep 
 tlie two halves apart by means of a small piece of wood ; open the pericardium ; be care- 
 ful not to mistake the pulmonary artery for the aorta ; raise up the aorta by a ligature ; 
 make an incision in it anteriorly, and introduce the pipe. Injections of the whole body 
 may also be made by introducing the tube into a large artery, such as the primitive ca- 
 rotid ; this mode of injection permits of injecting the heart and the cardiac arteries, and 
 of avoiding the mutilation of the arch of the aorta. The partial injections in a whole 
 subject are preferable to the general injections, especially when such substances as tal- 
 low are used, which are easily solidified. Of course, an indispensable condition for the 
 success of these partial injections is the previous isolation of the arterial system that 
 you wish to prepare. This isolation is effected by ligatures which are put upon the large 
 arteries communicating with the small arteries that are to be injected. 
 
 In injecting the coronary arteries, the pipe must be introduced into one of the carotids. 
 
 DESCRIPTION OF THE ARTERIES. 
 
 THE PULMONARY ARTERY. 
 
 Preparation. — Description. — Relations. — Size. — Development. 
 
 Preparation. — In order to inject the pulmonary artery, the injecting pipe must be in- 
 troduced into one of the venae cavse. 
 
 The pulmonary artery, called vena arteriosa by the older writers, because having all 
 the external characters of an artery ; it nevertheless contains black blood, extends from 
 the right ventricle to the two lungs. It arises {k, fig. 191) from the infundibuliform pro- 
 longation of the right ventricle, and then passes upward and to the left side, crossing in 
 front of the aorta, which is embraced by its concavity ; having reached the left side of 
 this artery, after a course of about fourteen or fifteen lines, it divides into two trunks 
 (k k, fig. 192), which proceed transversely, one to the right, the other to the left lung 
 (kk, fig. 171), where they terminate by dividing into branches. From the point of di- 
 vision into the right and left branches* a fibrous cord, the remains of the ductus arteri- 
 osus, proceeds in the original direction of the artery, and is attached to the concavity of 
 the arch of the aorta opposite the left subclavian artery. 
 
 At its origin the pulmonary artery is covered externally by the highest fibres of the 
 infundibulum ; internally it is provided with three sigmoid movable valves (a a a, fig. 
 196), which, when depressed, completely close the mouth of the vessel. By careful dis- 
 section, it is found that the pulmonary artery is cut at its origin into three festoons, cor- 
 responding to the sigmoid valves, and that it is connected to the tissue of the heart by 
 its intern5 coat, which is contiguous with the lining membrane of the right cavities of 
 the heart ; and also by prolongations given off from the fibrous zone, and attached to the 
 convex borders of the three festoons, and to the angular intervals between them. 
 
 Relations. — In front and on the left side the pulmonary artery is convex, and covered 
 by the serous layer of the pericardium, which is often separated from it by some fat ; be- 
 hind and on the right side it is concave, and is in relation with the aorta, which it em- 
 braces. The right and left auricles are in contact with its corresponding sides. 
 
 Size. — The left branch of the pulmonary artery is about one inch in length ; it is in 
 relation behind with the left bronchus, one of the bronchial arteries often passing between 
 them ; it is in direct relation with the aorta. In front, it is covered by the serous layer 
 of the pericardium, excepting near the lungs, where the pulmonary veins are placed in 
 front of the arterial branches. 
 
 The right division of the pulmonary artery is from sixteen to eighteen lines in length ; 
 it is in relation in front with the vena cava superior, and with the ascending portion of 
 the aorta, but not immediately, for the serous layer of the pericardium covers both the 
 aorta and the corresponding part of the pulmonary artery. Behind, it is in relation with 
 the right bronchus, and passes above the right auricle. 
 
 Development. — In the foetus, instead of the fibrous cord, which we have described as 
 proceeding from the point at which the pulmonary artery divides into its two branches,! 
 there is a canal called the ductus arteriosus, almost equal in diameter to the pulmonary 
 
 * See note, infrd. 
 
 t [It was noticed by Haller and Senac, that the ductus arteriosus in the foetus, and the cord to which it is 
 reduced after birth, arise, not from the angle of division into the right and left pulmonary arteries, but from 
 the left pulmonary artery itself : this is an interesting and important fact in reference to the development of 
 th« great vessels issuing from the heart.] 
 
THE AOETA. 
 
 d9l 
 
 artery itself, the course of which vessel it pursues ; at this time the right and left branch- 
 es of the pulmonary artery are very small. At birth the whole of the venous blood pro- 
 ceeds to the lungs, none of it passing through the ductus arteriosus, which then becomes 
 obliterated. 
 
 Fig. 198. 
 
 THE AORTA. 
 
 Preparation. — Definition. — Situation. — Direction. — Size. — Division into the Arch of the Am- 
 ta, the Thoracic Aorta, and the Abdominal Aorta. 
 Preparation. — The aorta may be studied without having been injected.* In order to 
 study it in an injected subject, the median incision made for the purpose of introducing 
 the injection must be prolonged down to the pubes. Then disarticulate the clavicles, 
 separate the two sides of the thorax, even so far as to break some of the ribs, and keep 
 them separate by introducing a piece of wood ; cut through the abdominal parietes, and 
 turn the left lung over to the right side. 
 
 The aorlo {aoprri, arteria magna, arteriamm omnium mater, ah c d,fig. 198), the com- 
 mon origin of all the arteries of the human body, commences at the left ventricle, and 
 terminates by bifurcating (at d) opposite the fourth lumbar vertebra. 
 
 Situation. — It is situated deeply in the thoracic and abdominal cavities, along the ver- 
 tebral column, which affords it both support and protection. In those animals in which 
 the aorta is prolonged beyond the trunk, the vertebral column accompanies the vessel, 
 and forms a bony canal or sheath for it, distinct from the canal for the spinal cord. 
 
 Direction. — Immediately after its origin, the aorta advances towards the right side (a, 
 fig. 198), and almost directly afterward pro- 
 ceeds upward, describing a slight curve, the con- 
 vexity of which is turned forward and to the 
 right, and the concavity backward and to the left. 
 After leaving the pericardium, it changes its 
 direction, becomes suddenly curved, and passes 
 almost horizontally from the right to the left, 
 and from before backward, to reach the left side 
 of the vertebral column, on a level with the third 
 dorsal vertebra, at which point (6) it makes a 
 third curve, and becomes vertical and descend- 
 ing. Having reached the diaphragm (at c), it 
 incUnes a little to the right side, in order to gain 
 the median line, and to pass through the ring, 
 or, rather, the canal, formed for it by the pillars 
 of the diaphragm. From this point to its ter- 
 mination, it rests upon the middle of the anteri- 
 or surface of the vertebral column. 
 
 Varieties in its Direction. — It is not a very 
 rare occurrence to find the aorta curving over 
 to the right instead of the left side — a disposi- 
 tion which may either be accompanied with a 
 complete transposition of the thoracic and ab- 
 dominal viscera, or may be independent of it. 
 
 Size. — The several portions of the aorta have 
 not a uniform caliber ;t but its gradual decrease, 
 in this respect, bears no direct proportion to 
 the number and size of the branches given off" 
 from it. 
 
 At its origin it always presents three ampul- 
 lae, which correspond to the sigmoid valves ; 
 they are called the sinuses of the aorta, or sinuses 
 of Valsalva. They exist originally, and must, 
 therefore, be distinguished from a dilatation 
 found on the convex side of the arch of the aor- 
 ta in old subjects, and called the great sinus of 
 the aorta. This dilatation results entirely from the impulse of the current of the blood. 
 
 The caliber of the aorta, moreover, differs exceedingly in different subjects, even 
 when there is no appreciable organic lesion :t it should be remarked, however, that the 
 thickness of its coats is not at all in proportion with its caliber. 
 
 * It will be advantageous to study the aorta in the same subject in which the viscera have already been ex- 
 amined. 
 
 t Thus, the caliber of the commencement of the aorta, compared with that of its termination, is generally 
 as five to three ; hence the diminution is not by any means proportionate to the number of branches arising 
 from It, for the united calibers of its collateral braiiches would much exceed that of the main vessels. 
 
 t Thus, I have seen a case in which the aorta was 4 inches 8 lines in circumference opposite the arch, and 
 2 inches 6 lines at its lower end : the latter is the usual size of the vessel. 
 
502 ANGEIOLOGY. 
 
 The aorta is generally divided into three portions, viz., the arch of the aorta, the tho- 
 racic aorta, and the abdominal aorta. The two latter portions form together the aorta de- 
 acendens. 
 
 The Arch of the Aorta. 
 
 I shall give this name to all that part of the aorta (a I, fig. 198^ which is comprised 
 between its origin from the left ventricle and the point where it is crossed by the left 
 bronchus.* 
 
 The direction of the arch of the aorta is neither transverse nor antero-posterior, but 
 oblique from the right to the left side, and from before backward ; so that it is anterior, 
 median, and substernal in its first portion, and posterior at its termination, and in rela- 
 tion with the left side of the vertebral column. In consequence of these relations, aneu- 
 risms of the anterior part of the arch of the aorta frequently affect the sternum, while 
 aneurisms of the posterior portion affect the vertebral column. 
 
 Relations. — We shall examine the relations of the arch of the aorta, first in its pericar- 
 diac or ascending portion, and then in its horizontal and descending portions taken to- 
 gether. 
 
 The Pericardiac Portion (/, fig. 191). — Concealed, as it were, in the substance of the 
 heart at its origin, it is in relation in front with the infundibulum of the right ventricle, 
 and behind with the concavity of the auricles, which are moulded upon it. On the right, 
 it rests upon the groove between the infundibulum and the right auriculo-ventricular or- 
 ifice ; on the left, it is in relation with the puhnonary artery. It is important to note 
 the practical consequences of these relations. I have recently seen a communication 
 between the aorta and the infundibulum. Again, aneurisms of the origin of the aorta 
 may burst into the auricles. 
 
 After leaving: the heart, this portion of the aorta is surrounded on all sides, but to a 
 greater extent in front than behind, by the serous layer of the pericardium, which forms 
 a sort of additional coat for it, excepting in front, below, and on the left side, where it is 
 in immediate contact with the pulmonary arteiy, as that vessel turns round it. Behind, 
 this portion of the aorta is in relation with the right division of the pulmonary artery ; 
 on the right, with ttie vena cava superior. It follows, therefore, that the pulmonary ar- 
 tery on the one hand, and the aorta on the other, form two half-rings, like the branches 
 of the letter x, which embrace each other by their concavities. The pericardiac portion 
 of the aorta is situated oeneath the sternum, from which it is separated by the pericar- 
 dium and the anterior mediastinum 
 
 The Second Portion, comprising the Horizontal and Descending Portions of the Arch. — 
 On the outside of the pericardium, the aorta is in relation, in front and on the left side, 
 with the left pleura, and is separated by it from the corresponding lung, which is exca- 
 vated at that point. The phrenic and pneumogastric nerves are also in immediate con- 
 tact with it. Behind, and on the right side (/, fig. 171), it is in direct relation with the tra- 
 chea, the commencement of the left bronchus, the oesophagus, the thoracic duct, the re- 
 current nerve, the vertebral column,t and a great nmnber of lymphatic glands. 
 
 By its convexity, which is directed upward, it gives origin to three large arterial trunks, 
 viz., proceeding from the right to the left side, the brachio-cephalic (e,fig. 198) or innom- 
 inate, the left common carotid (f), and the left subclavian {g) arteries. The highest point 
 of the arch is opposite the origin of the brachio-cephalic artery in the infant, and that of 
 the left subclavian in old subjects. The distance between the fourchette of the sternum 
 and the highest point of the aortic arch varies in different ages and individuals : it is 
 generally from ten to twelve lines in the adult ; it is much less in the aged and in the 
 newborn infant, but for very different reasons ; in the infant it is owing to the undevel- 
 oped condition of the sternum, but in advanced age it depends upon dilatation of the arch 
 of the aorta ; in some adults, also, we find the distance very inconsiderable, and this is 
 important in reference to the operation of tracheotomy. 
 
 By its concavity, which is directed downw^ard, the arch of the aorta is in relation with 
 the left recurrent nerve, which embraces it, as it were, in a loop, having its concavity 
 turned upward; with the left bronchus (p,fig. 171 ; also,^"'. 198), which is placed be- 
 hind the horizontal portion of the arch, and then becomes situated in front of its descend 
 ing portions, so that the aorta, during its curvature, has two different relations with this 
 air-tube ; and, lastly, with a very great number of lymphatic glands, which in some 
 measure fill up the concavity of the aortic arch. 
 
 Anomalies of the Arch of the Aorta.— A very remarkable anomaly of the arch of the 
 aorta has been observed, in which the vessel, being simple at its origin, divides into two 
 trunks, which pass, one in front and the other behind the trachea, and then reunite to 
 form the descending aorta. The aorta sometimes presents traces of a subdivision into 
 
 * The limits of the arcn of the aorta are not weJ defined : most authors exclude the first curve of the ar- 
 tery The lower boundary is marked by the origin of the left subclavian, according to some ; by the left bron- 
 chus, according to others ; and. lastly, according to a great many, by the articulation of the fourth with the 
 fifth dorsal verteora, 
 
 t I have, I believe, satisfactorily demonstrated, in another part of this work, that the left lateral concaviti 
 »f the vertebral column was owing to the presence of the arch of the aorta 
 
BRANCHES OF THE AORTA. Mg 
 
 two from its origin ; such a case appears to indicate a fusion of two aortas into one, for 
 we then find five sigmoid valves. 
 
 The Thoracic Aorta. 
 
 The thoracic aorta {b c, Jig. 198) is situated in the posterior mediastinum, along the lelt 
 side of the vertebral column, and it projects into, and encroaches upon, the left cavity 
 of the chest. 
 
 Relations. — It corresponds, on the left side, with the lung, from which it is separated 
 by the left wall of the posterior mediastinum ; on the right, it is in relation with the 
 oesophagus, the vena azygos, and the thoracic duct ; in front, with the left pulmonary m- 
 teries and veins above ; with the oesophagus (h) below, which canal becomes anterior to 
 it before passing through the oesophageal opening in the diaphragm, and with the peri- 
 cardium in the middle, by which it is separated from the posterior surface of the heart ; 
 behind, it is in relation with the vertebral column, the thoracic duct passing between 
 them above. 
 
 The thoracic aorta is surrounded by an abundance of cellular tissue, and by a number 
 of lymphatic glands. 
 
 Diaphragmatic Portion of the Thoracic Aorta. — The diaphragm does not form a simple 
 orifice or an aponeurotic arch for the aorta, but its crura (« s,fig. 199) are arranged into 
 a muscular semi-canal, from fifteen to eighteen lines in length, and terminating below 
 by a tendinous arch. The aorta is accompanied, while passing through this canal, by 
 the thoracic duct* and the vena azygos, and it inclines a little to the right side, in order 
 to become anterior to the vertebral column. 
 
 The Abdominal Aorta. 
 
 The abdominal aorta (c d,Jig. 198) occupies the middle part of the anterior surface ot 
 the vertebral column, and is in relation on the right side with the vena cava inferior, and 
 in front with the pancreas and the third portion of the duodenum, which rests immedi- 
 ately upon it ; in the rest of its extent it corresponds with the adherent borders of the 
 mesentery, and with the peritoneum covering the lumbar region of the vertebral column. 
 The stomach and the convolutions of the small intestine separate the aorta from the an- 
 terior parietes of the abdomen. When the small intestine fdi&s down into the pelvis, the 
 abdominal aorta may be felt immediately behind the wall of the abdomen, and may be 
 easily compressed there, so as completely to intercept the passage of the blood, t 
 
 BRANCHES FURNISHED BY THE AORTA IN ITS COURSE. 
 
 Enumeration and Classification. — Arteries arising from the Aorta at its Origin, viz., the Car- 
 onary or Cardiac. — Arteries arising from the Thoracic Aorta, viz., the Bronchial, tie 
 (Esophageal, the Intercostal. — Arteries arising from the Abdominal Aorta, viz., the Lum- 
 bar, the Inferior Phrenic, the Caliac Axis, including the Coronary of the Stomach, the He- 
 patic and the Splenic, the Superior Mesenteric, the Inferior Mesenteric, the Spermatic, the 
 Renal, and the Supra-renal or Capsular. 
 
 The aorta is the common trunk of all the branches and twigs given off by the arterial 
 tree. It alone furnishes, therefore, all the arteries of the human body. The branches 
 which come from it I shall divide into terminal and collateral branches. 
 
 The terminal branches of the aorta consist of the middle sacral and the two commcm 
 iliac arteries. The collateral branches are very numerous : they may be divided into 
 those arising from the pericardiac portion of the aorta, viz., the coronary or cardiac ar- 
 teries; those arising from the aortic arch, viz., the brachio-cephalie, the left common 
 carotid, and the left subclavian : these we may consider as terminal arteries, which, ta- 
 ken together, have been termed the ascending aorta in opposition to the descending 
 aorta ; those arising from the thoracic aorta, which may be subdivided into the parietal 
 branches, viz., the intercostals and the visceral, viz., the bronchial, oesophageal, and 
 mediastinal arteries ; and, lastly, those arising from the abdominal aorta, which may 
 also be distinguished as the parietal, viz., the lumbar and inferior phrenic arteries, and 
 the visceral, viz., the cceliac axis, the superior and inferior mesenteric, the supra-renal, 
 the renal, and the spermatic arteries. 
 
 Artekies ari^no from the Aorta at its Origin. 
 The Coronary or Cardiac Arteries. 
 Dissection. — Take off the serous membrane from the heart, and also the fat which oo- 
 
 * It is a mistake to say that the right azygos vein passes through the same opening as the thoracic duct. 
 The ar.ygos vein traverses the evening which is destined to tVie passage of the great splanchnic branch of the 
 sympathetic nerve. 
 
 t This compression is very easily applied in women immediately after parturition, both in consequence of 
 the relaxed state of the abdominal parietes allowing them to be readily depressed, and also from the facility 
 with which the small intestines are moved aside. 
 
504 ANGEIOLOGY. 
 
 cupies the furrows ; in order to see distinctly the origin of these arteries, remove the 
 pulmonary artery and the infundibulum of the right ventricle. 
 
 The cardiac or coronary arteries {see figs. 191, 192), the nutritious vessels of the heart, 
 or, as it were, its rasa vasorum, are two in number, and are named right and left on ac- 
 count of their origin, and also anterior and posterior from their distribution. Their 
 number is not constant. Thus the two coronary arteries sometimes arise by a common 
 trunk, to the left of the pulmonary artery.* Sometimes there arc three coronary arter- 
 ies ; Meckel has seen four ; but these varieties in number do not affect their distribu- 
 tion, for the supernumerary arteries merely represent branches, which, instead of arising 
 from the coronary arteries themselves, proceed directly from the aorta. I have recently 
 seen the right coronary artery arise from the aorta by three branches in juxtaposition, 
 one of which was of considerable size : the others were small. 
 
 Origin. — They arise from the anterior part of the circumference of the aorta, imme- 
 diately above the free margin of the sigmoid valves, at the highest points of the two 
 corresponding sinuses. The origins of these vessels are so situated, that their orifices 
 are not covered by the valves when these latter are applied to the walls of the aorta, so 
 that the heart receives its arterial blood at the same time as all the other organs. The 
 angle at which the coronary arteries arise is extremely obtuse, so that the course of the 
 blood in them is completely retrograde. 
 
 The coronary arteries differ from each other in caliber, the right being larger than the 
 left, and also in their course, so that a special description is requisite for each. 
 
 The left or anterior coronary artery is destined principally for the anterior furrow of the 
 heart ; it is concealed, at its origin, by the infundibulum, from between which and the 
 left auricula it then escapes, and entering {e, fig. 191) the anterior furrow of the heart, 
 traverses it in a very tortuous manner, and anastomoses, at the apex, with the right or 
 posterior coronary artery. Not unfrequently this artery divides into two branches, one 
 of which runs along the anterior furrow, while the other passes upon the anterior sur- 
 face of the left ventricle. In this course, opposite the base of the ventricles, the artery 
 gives off an auriculo- ventricular branch, which, arising at a right angle, enters the left 
 auriculo-ventricular furrow, and, passing along it, turns round the base of the left ven- 
 tricle, as far as the posterior inter- ventricular furrow {e,fig. 192), where it anastomoses 
 with the right coronary artery. 
 
 The right or posterior coronary arteiy is larger than the left ; it arises to the right of 
 the infundibulum, between that part and the right auricle. Immediately after its origin 
 it is surrounded with a large quantity of fat, and turns directly, so as to gain the right 
 auriculo-ventricular furrow. At the upper end of the posterior inter-ventricular furrow 
 (e, fig. 192) it bends at a right angle, and entering the furrow, runs along it to the apex 
 of the heart, where it anastomoses with the left coronary artery. At the point where it 
 changes its direction, the right coronary artery gives off a branch, which anastomoses 
 with the auriculo-ventricular branch of the left artery. 
 
 From this description, it follows that the cardiac arteries and their principal divisions 
 occupy the furrows of the heart ; that they form two vascular circles, which are placed 
 at right angles to each other like the furrows themselves ; that the auriculo-ventricular 
 circle is formed on the right by the trunk of the right cardiac, and on the left by a branch 
 of the left cardiac artery ; that the vessels forming these two circles are tortuous, but 
 especieilly those on the ventricles, because that part of the heart is subject to greater 
 variations in its dimensions than the part with which the auriculo-ventricular circle is 
 in relation; and, lastly, that both coronary arteries anastomose by inosculation, and 
 therefore can easily supply each other. 
 
 All the arteries of the heart proceed from these two circles. The auriculo-ventricular 
 circle gives off some ascending or auricular branches, an aortico-pulmonary branch to the 
 origins of the aorta and pulmonary artery, and an adipose branch, all of which were 
 pointed out by Vieussens ; also some descending or ventricular branches, the two prin- 
 cipal of which run somewhat obliquely along the right and left borders of the heart. 
 
 The ventricular circle gives off branches which penetrate the fleshy fibres at right an- 
 gles. A large artery, which has been described as the artery of the septtim, appears to be 
 one of the terminal branches of the left coronary artery ; it dips into and is lost in the 
 substance of the septum. 
 
 Lastly, the coronary arteries communicate with the bronchial. They are very liable 
 to calcareous deposites.f 
 
 Arteries abising from the Thoracic Aorta. 
 These may be divided into visceral branches, all of which arise from the front of the 
 
 * The coronary arteries were denominated by the older anatomists, and especially by Bartholin, coronaria 
 ntedo simplex, modo gemina. Meckel, Harrison, and others have described cases in which there was but on« 
 coronary artery. According to the descriptions of writers on comparative anatomy, that disposition is natural 
 with the elephant. 
 
 t It is not uncommon from such deposites to find cardiac arteries which are extremely narrowed, and even 
 obliterated. Several pathologists have considered this ossification of the cardiac arteries as the cause of those 
 phenomena which are designated by the name of angina vecions ; but tliis opinion is a mere hypothesis. 
 
THE AORTIC INTERCOSTAL ARTERIES. 505 
 
 aorta, viz., the bronchial and the oesophageal, and parietal branches, which arise from the 
 back of the aorta, viz., the aortic intercostals. 
 
 The Bronchial Arteries. 
 
 Dissection. — Carefully take away the heart and pericardium, dissect the bronchi, and 
 trace these arteries both to their origin and towards their termination. 
 
 Number and Origin. — The bronchial arteries {see fig. 198) vary much both in number 
 and origin. There are generally two on each side ; but sometimes there are three, or 
 even four, arising either at different heights or by a common trunk. Occasionally, one 
 of them arises from the subclavian, or from the internal mammary, or, rather, from the 
 first intercostal, or, lastly, from the second, or even the third intercostal artery. 
 
 I have seen the inferior thyroid artery give off a bronchial artery, which, after run- 
 ning along the trachea, passed in front of the right bronchus, and anastomosed freely 
 with the right bronchial furnished by the aorta. The right bronchial artery is always 
 larger than the left. 
 
 Whatever be their origin, the bronchial arteries pursue a tortuous course to the cor- 
 responding bronchus, and are usually situated on its posterior surface. When the right 
 bronchial artery arises from the aorta, it crosses obliquely over the lower part of the tra- 
 chea. The bronchial arteries always give some branches to the oesophagus ; a very 
 great number to the bronchial glands ; also several to the left auricle : they anastomose 
 with the coronary arteries on the one hand, and with the inferior thyroid and the supe- 
 rior intercostal arteries on the other. 
 
 Haller believes that the terminations of the bronchial arteries anastomose with the di- 
 visions of the puhnonary artery, and says that he has seen free and evident communica- 
 tions between them.* 
 
 The (Esophageal Arteries. 
 
 The oesophageal arteries {h,fig. 198) vary in number from three to seven, and are re- 
 markable for their slenderness and length. They arise in succession from the front of 
 the aorta, which they leave at right angles, and inamediately curve downward to reach 
 the front of the oesophagus, where they divide into extremely slender ascending, and 
 into very long descending branches, from which are given off a numerous series of twigs. 
 The superior oesophageal artery almost always anastomoses with the bronchial arteries, 
 and the oesophageal branches of the inferior thyroid. The inferior oesophageal artery 
 anastomoses with the oesophageal branches derived from the left inferior phrenic, and 
 from the coronary artery of the stomach. 
 
 The branches from the oesophageal arteries perforate the muscular coat of the oesoph- 
 agus, ramify in the sub-mucous cellular tissue, and terminate in a network in the sub- 
 stance of the mucous membrane. 
 
 The Aortic Intercostal Arteries. 
 
 Dissection. — In order to see the posterior branches, dissect the posterior spinal mus- 
 cles, and open the vertebral canal. To see the anterior branches or the intercostals, 
 properly so called, expose these vessels on the inside of the parietes of the chest in the 
 first half of their course, and then on the outside of the chest to their termination. 
 
 The aortic or inferior intercostals (i i i' i'.fig. 198), so named to distinguish them from 
 the superior intercostal, a branch of the subclavian, and from the anterior intercostals, 
 derived from the internal mammary, are generally eight or nine in number, the upper 
 two or three intercostEil spaces being supplied by the superior intercostal branch of the 
 subclavian. 
 
 The varieties in their number depend upon the number of intercostal spaces which are 
 supplied with branches from the subclavian, and also upon the number of intercostal ar- 
 teries which arise by a common trunk. 
 
 Origin. — ^They arise at various angles from the back of the aorta ; the superior gen- 
 erally at an obtuse angle to gain the spaces situated above them ; the succeeding ones 
 at different angles, which are less and less obtuse, and sometimes right angles, or even 
 acute angles. In the latter case, the vessel immediately ascends to reach the intercostal 
 space for which it is intended. The right and left intercostals are of equal size, and there 
 is little difference in this respect between the superior and the inferior intercostals. 
 
 In consequence of the aorta being situated towards the left side, the right intercostals 
 (i' i') are longer than the left. They turn over the body of each dorsal vertebra, passing 
 Dchind the oesophagus, the thoracic duct, and the vena azygos, and reach the correspond- 
 ing intercostal space. The left intercostals enter their proper spaces at once. Bot h are 
 in relation with the costal pleura and the thoracic ganglia of the great sympathetic nerve, 
 behind which they are situated. The lower intercostals on the left side are covered by 
 the vena azygos minor. The two lower intercostals on both sides are covered by the 
 pillars of the diaphragm. In their course over the bodies of the vertebras, the intercos- 
 tals give off numerous nutritious branches, which enter the foramina on the anterior sur- 
 face of these bones. 
 
 See note, p. 421. 
 S 8 3 
 
ANGEIOLOGY. 
 
 On reaching the intercostal space, each artery immediately divides into an anterior 
 and a posterior branch. 
 
 The anterior or intercostal branches are larger than the posterior, and may be regarded 
 as the continuation of the arteries themselves in their original course. They are at first 
 situated in the middle of the intercostal spaces, between the pleura and external inter- 
 costal muscles ; they then pass between the external and the internal intercostals, reach 
 the lower border of the rib above them, and are lodged in the grooves found in that sit- 
 uation ; having reached tlie anterior third of the intercostal spaces, where they have be- 
 come extremely small, they quit the grooves, and again become placed in the middle of 
 the spaces ; the superior intercostals then terminate by anastomosing with the intercostal 
 branches of the internal mammary, and the inferior intercostals with the epigastric, the 
 phrenic, the lumbar, and the circumflex iliac arteries 
 
 During its whole course, each intercostal branch is in relation with the corresponding 
 intercostal vein and nerve. The inferior intercostal arteries, commencing at the fifth, 
 after leaving the intercostal spaces, are lost in the external and internal oblique muscles 
 of the abdomen, which, as we have seen, form, as it were, continuations of the intercostal 
 muscles (see Myology). 
 
 The intercostal branch furnishes numerous ramusculi to the intercostal muscles, the 
 ribs, the sab-pleural cellular tissue, the muscles which cover the thorax, and even to the 
 integuments. A very small, but tolerably constant branch, is given off at an acute angle 
 from the artery, at the moment where it dips between the two sets of intercostals, gains 
 the upper border of the rib below, and is lost in the periosteum and the muscles, after 
 running a variable distance. 
 
 The posterior or dorsi-spinal branches pass directly backward between the transverse 
 processes of the vertebrae, on the inner side of the superior costo-transverse ligaments, 
 and each of them immediately divides into two branches : one, the spinal, which enters 
 the inter-vertebral foramen, and again divides into a vertebral branch for the bodies of the 
 vertebrae, and a medullary branch for the coverings of the spinal cord, and for the cord it- 
 self, to the distribution of which we shall hereafter return. The second, or dorsal branch, 
 is larger than the spinal, and forms a continuation of the dorso-spinal ttunk ; it escapes 
 behind between the transverso-spinalis and longissimus dorsi, sends some ramifications 
 between the longissimus dorsi and sacro-lumbalis, and terminates in the muscles and the 
 skin. 
 
 Artkkies arising fkom the Abdominal Aorta. 
 
 The branches furnished by the abdominal aorta are parietal, viz., the lumbar and the 
 inferior phrenic arteries; and the visceral branches, viz., the cxliacaxis, the superior and 
 inferior mesenteric, the spermatic, the renal, and the middle supra-renal arteries. In refer- 
 ence to their place of origin, these arteries may be divided into those which arise from 
 the anterior aspect of the aorta, viz., the coeliac axis, the superior and inferior mesenter- 
 ic, and tne- spermatic arteries ; and those which arise from its sides, viz., the renal, the 
 middle supra-renal, and the lumbar arteries. The lumbar arteries might be regarded as 
 arising from the back of the aorta. 
 
 The Lumbar Arteries. 
 
 ?%r. 199. 
 
 Dissection. — Remove the pillars of tlie diaphragm 
 and the psoas muscles. In order to expose the 
 dorsi-spinal branches, dissect the posterior spinal 
 muscles, and open the vertebral canal. To ex- 
 pose the anterior branches, dissect the abdominal 
 muscles carefully. 
 
 The lumbar arteries {I I, fig. 199) continue the 
 series of intercostals, with which they present nu- 
 merous analogies in reference to their origin, 
 course, and termination. They vary in num- 
 ber from three to five, but there are usually four. 
 These varieties depend either upon the greater or 
 less size of the ilio-lumbar artery, which bears the 
 same relation to the lumbar arteries as the superior 
 intercostal does to the aortic intercostals, and 
 which sometimes takes the place of the last, some- 
 times of the last two lumbar arteries ; or the va- 
 rieties may depend on several lumbar arteries ari- 
 sing from a common trunk. 
 
 Origin. — The lumbar arteries are given off at 
 right angles from the back of the aorta. Very 
 rarely the right lumbar arteries arise by a common 
 trunk with the left. 
 
 Course. — They proceed transversely in the 
 grooves on the bodies of the vertebrae, and pass 
 
THE INFERIOR PHRENIC ARTERIES, ETC. 507 
 
 under the tendinous arches of the psoas, by which muscle they are covered. They send 
 a great number of branches to the bodies of the vertebrae ; and having reached the base 
 of the transverse processes, each of them divides into tvt^o branches, a posterior or dar- 
 n-spinal, and an anterior or abdominal branch. 
 
 The posterior branch, which is analogous to the dorsi-spinal of an intercostal artery, di- 
 vides into two branches : one, the spinal, which enters the spinal canal through the in- 
 ter-vertebral foramen, and subdivides into a vertebral branch for the body of the vertebra, 
 and a medullary branch for the cord and its coverings ; the other branch is the dorsal, 
 which terminates in the muscles and integuments of the lumbar region. 
 
 The antericrr branch is smaller, and analogous to the anterior branch of an intercostal 
 artery : it is situated between the quadratus lumborum and the middle layer of the apo- 
 neurosis of the transversalis, and ramifies in the substance of the abdominal muscles. 
 The anterior branch of the first lumbar artery runs along the lower border of the twelfth 
 rib, passes obUquely downward and forward, and divides into two ramuscuU, one of which 
 continues in the same course, while the other turns downward to the crest of the ihum. 
 The anterior branches of the second and third pair of lumbar arteries are generally small : 
 not unfrequently the third artery is wanting. The anterior branch of the fourth lumbar 
 artery runs along the crest of the ilium, and sends branches to the muscles of the abdo- 
 men and to the iUacus and glutaei muscles. 
 
 The Inferior Phrenic Arteries. 
 
 Dissection. — Careful.y detach the peritoneum from the lower surface of the diaphragm. 
 
 The inferior phrenic or diaphragmatic, or the sub-diaphragmatic arteries {d d. Jig. 199), so 
 named in contradistinction to the superior phrenic, which are branches of the internal 
 mammary, are so frequently derived from the coeliac axis, that some anatomists, Meckel 
 among others, describe them as branches of that trunk. They are two in number, a 
 right and a left. They arise from the aorta, immediately below the cordiform tendon of 
 the diaphragm, either side by side, or by a common trunk. Sometimes they arise from 
 the coeliac axis itself, or, rather, from the coronary artery of the stomach, from the renalj 
 or from the first lumbar artery ; in some subjects we find as many as three or four. 
 
 Each artery passes upward and outward in front of the corresponding pillar of the dia- 
 phragm, gives some twigs to this pillar, and one to the supra-renal capsule, and then di- 
 vides into two branches, an internal and an external. The internal branch passes direct- 
 ly forward, ramifies and anastomoses by loops with the vessel of the opposite side around 
 the oesophageal opening, behind the cordiform tendon of the diaphragm. The exteriial 
 branch is larger and more tortuous than the preceding ; it proceeds obliquely outward, 
 between the peritoneum and the diaphragm, and divides into a great number of branches, 
 which extend as far as the attachments of this muscle, where they anastomose with the 
 intercostal and the internal mammary arteries. 
 
 The right inferior phrenic artery, moreover, sends some branches into the coronary 
 ligament of the liver ; the left artery gives off a branch to the oesophagus, which enters 
 through the oesophageal opening in the diaphragm, and joins the oesophageal branches 
 derived from the coronary artery of the stomach and from the aorta. 
 
 The Cceliac Axis, 
 
 Dissection. — Elevate the liver by means of hooks, or by a ligature fixed to the right 
 side of the chest ; depress the stomach ; divide the fold of peritoneum by which these 
 two viscera are united ; and search for the coeliac axis between the pillars of the dia- 
 phragm, by removing the solar plexus of nerves, which forms a thick layer in front of it. 
 
 The caliac axis or artery (from KoiXia, the belly or stomach, y, fig. 199), le tronc opis- 
 thogastrique, Chauss. {oTTiadev, behind, yaarrip, the stomach), supplies the stomach, the 
 liver, the spleen, the pancreas, and the great omentum. It is remarkable for its size, 
 being larger than any of the other branches of the abdominal aorta, not excepting the 
 superior mesenteric ; for arising at a right angle from the front of the aorta, immediate- 
 ly below the phrenic arteries ; for its horizontal course, which is rarely more than five 
 or six lines in extent, and for its very early division into three branches, ad modum tri- 
 dentis. These three branches are of unequal size : they are the coronary artery of the 
 stomach {b, fig. 200), the hepatic (c), and the splenic (d), which, together, are called the 
 caliac tripos, or the tripos of Holler. 
 
 In its short course the coeliac axis is in relation with the lesser curvature of the stom- 
 ach, or, rather, with the gastro-hepatic omentum, behind which it is situated ; on the 
 left side, it is in relation with the cardia ; below, with the upper border of the pancreas, 
 upon which it rests ; above, with the left side of the lobulus Spigelii. It is surrounded 
 by so large a plexus of nerves, that it cannot be exposed until the plexus is removed. 
 
 The Coronary Artery of the Stomach. 
 The coronary artery of the stomach, or the superior gastric {b,figs. 200, 201), is the small- 
 est branch of the coeliac axis. It is directed upward and to the left side, to reach the 
 (Esophageal orifice of the stomach ; it then turns suddenly to the right side, pursues a 
 
90i 
 
 ANGEIOLOGY. 
 
 Fig. 200. 
 
 semicircular course along the lesser curvature 
 (arteria coronaria ventriculi), and terminates by in 
 osculating with the pyloric artery (e), a branch 
 from the hepatic. 
 
 In this course it gives off from its convex bor- 
 der ascending (esophageal branches, which peiss 
 through the (Esophageal opening of the dia- 
 phragm, ascend upon the oesophagus, and are 
 there distributed like the aortic oesophageal 
 branches, with which they anastomose ; also car- 
 diac branches, which form a vascular network 
 around the oesophageal opening of the stomach, 
 and pass transversely upon its great tuberosity ; 
 and a series o( gastric branches, which arise along 
 the lesser curvature, and are divided into two 
 sets, an anterior set for the front, and a posterior 
 set for the back of the stomach. No branch ari- 
 ses from the concavity of the curve formed by 
 this artery. 
 
 Not unfrequently the coronary artery of the 
 stomach gives off an hepatic branch, and hence 
 the first branch of the coeliac axis has been called 
 the gastro-hepatic by some anatomists. In such 
 cases, as may be conceived, this artery is very 
 large. It is also not uncommon to find the left 
 inferior phrenic arising from it. 
 
 The Hepatic Artery. 
 
 The hepatic artery (c, Jigs. 200, 201) is larger than the preceding. It passes trans- 
 versely from the left to the right side, describing a curve, having its concavity directed 
 upward, and moulded, as it were, upon the lobulus Spigelii. Near the pylorus it chan- 
 ges its direction, and passes upward to the transverse fissure of the liver, where it di- 
 vides into two branches. In the latter part of its course it is contained within the gas- 
 tro-hepatic omentum, in front of the foramen of Winslow, and is in relation with the 
 ductus choledochus and the vena portse, the vein being placed behind both the artery 
 and duct. 
 
 It is not uncommon to find two hepatic arteries, one derived from the coronary of the 
 stomach, and the other from the superior mesenteric. Sometimes there are even three 
 hepatic arteries, one from the coronary of the stomach, a second from the superior mes- 
 snteric, and a third from the coeliac axis. 
 
 Collateral Branches. — The hepatic artery gives off three collateral braiiihes, the pylo- 
 ric, the right gastro-epiploic, and the cystic. 
 
 The pyloric artery, also named the small right gastric artery, to distinguish it from the 
 coronary artery of the stomach, which was called the left gastric (c), is a small vessel 
 which arises from the hepatic, near the pylorus : it runs from right to left along the 
 pylorus and the lesser curvature of the stomach, and inosculates with the coronary ar- 
 tery (6) of that viscus. Two sets of branches, an anterior and a posterior, arise from 
 its convex border, and are distributed to the stomach and the first part of the duodenum, 
 in the same manner as those from the coronaria ventriculi itself Not unfrequently the 
 pyloric artery terminates near the pylorus, without anastomosing with the coronary. 
 
 T\ie right gastro-epiploic artery (f,figs. 200, 201) is remarkable for its size and for its 
 length. It passes vertically downward, behind the first portion of the duodenum, near 
 the pylorus. Having reached below the duodenum, it changes its direction, passes from 
 right to left (Z) along the great curvature of the stomach, where it inosculates with the 
 left gastro-epiploic {h, fig. 201). In one case, where the hepatic artery was given off 
 by the superior mesenteric, the right gastro-epiploic arose directly from the coeliac axis. 
 
 The first portion of this vessel, usually called the gastro-duodenal artery, furnishes sev- 
 eral branches to the pylorus, which may be called the inferior pyloric ; it then gives a 
 branch to the duodenum and the head of the pancreas, named the pamreatico-duodena- 
 lis (k), and remarkable for its anastomosing with the superior mesenteric ; an arrange- 
 ment that leads, as it were, to the cases in which the hepatic itself is derived from the 
 last-mentioned artery ; it is also remarkable for its size, which is sometimes such that 
 the continuation of the vessel, the right gastro-epiploic artery proper, is only half the 
 size of the trunk from which it is given off (the gastro-duodenal). 
 
 In its horizontal portion along the great curvature of the stomach, the right gastro- 
 epiploic sends both ascending and descending branches : the former, or gastric branches, 
 divide into two sets ; one for the anterior, and one for the posterior surface of the stom- 
 ach The latter, or epiploic branches (g g, fig. 200J, are extremely long and slender ; 
 
THE SPLENIC AND SUPERIOR MESENTERIC ARTERIES. 509 
 
 they pass downward parallel to each other, without any windings, in the substance of 
 the two anterior layers of the great omentum, are reflected upward at its lower border, 
 just as the two layers are themselves, and accompany them as far as the transverse 
 colon, to which they are distributed. 
 
 The cystic artery (i, fig. 200) is a small vessel which almost always arises from the 
 right of the terminal divisions of the hepatic artery, reaches the neck of the gall-blad- 
 der, and divides into two branches ; one superior, running between the liver and the 
 vesicula, the other inferior, which pursues a tortuous course between the peritoneum 
 and the proper coat of the gall-bladder, divides and subdivides, and is finally distributed 
 to the mucous membrane. 
 
 Termhial Branches. — Of the two terminal branches of the hepatic artery, one dips into 
 the right extremity of the transverse fissure of the liver, and the other into the left ex- 
 tremity of the same fissure : in these situations they become applied to the correspond- 
 ing branches of the vena portae and hepatic duct, are enclosed with them in the capsule 
 of Glisson, and closely accompany the corresponding ramifications of those vessels 
 through all their divisions and subdivisions. 
 
 The Splenic Artery. 
 
 The sflenic artery {d, figs. 200, 201) is larger Fig. ZOi. 
 
 than either of the other divisions of the cceliac 
 axis. Immediately after its origin it is received 
 into a shght groove formed along the whole of the 
 upper border of the pancreas (i). It passes from 
 the right to the left side, and is exceedingly tor- 
 tuous in its course :* having reached the hilus 
 of the spleen, it divides into a great number of 
 terminal branches (w, fig. 201), which enter that 
 organ separately. It is not rare to find one of 
 these branches detached from the others, to be 
 distributed either to the upper or the lower end 
 of the spleen. 
 
 Near the spleen, the splenic artery and its di- 
 visions are enclosed within the gastro-splenic omentum. 
 
 The relations of the splenic artery to the posterior surface of the stomach explains 
 how, in certain cases of ulceration of the stomach opposite the pancreas, this artery 
 may become the source of haematemesis. 
 
 The splenic artery gives off several collateral branches : 
 
 The pancreatic arteries (i i), which are variable in number, and are very large, consid- 
 ering the size of the organ to which they are distributed. 
 
 The left gastro-epiploic artery (h), which often arises from one of the divisions of the 
 splenic, passes vertically downward, behind the great end of the stomach, gains the 
 great curvature, along which it runs from left to right, and anastomoses with a branch 
 of the hepatic, viz., the right gastro-epiploic (l) ; like which artery, it sends off ascending 
 or gastric, and descending or epiploic branches. The size of the gastro-epiploica sinistra 
 varies much, and has an inverse proportion to that of the gastro-epiploica dextra. 
 
 The vasa brevia (o o), which are remarkable for their number and shortness, generally 
 arise from one or several of the terminal branches of the splenic artery, just as these 
 are entering the spleen ; they pass directly, by a retrograde course, from that organ to 
 the great cul-de-sac of the stomach, as far as the cardia, where they anastomose with 
 the cardiac branches of the coronary artery of the stomach. 
 
 From the preceding description of the branches of the cceliac axis, we perceive that 
 the stomach is surrounded by an uninterrupted arterial circle, formed by the right and 
 left gastro-epiploic, by the pyloric, and by the coronary arteries ; and that, secondly, the 
 branches derived from this circle constitute an anastomotic network upon the anterior 
 and posterior surfaces of the stomach. 
 
 The Superior Mesenteric Artery. 
 
 Dissection. — Look for the origin of the artery between the pancreas and the third por- 
 tion of the duodenum ; turn the whole of the small intestines to the left side ; remove 
 with care the right layer of the mesentery, the left layer of the right lumbar mesocolon, 
 the inferior layer of the transverse mesocolon, and the numerous lymphatic glands which 
 conceal the artery and its divisions. 
 
 The superior mesenteric artery (below y,fig. 199) is the artery of the small intestine, 
 and of the right half of the large intestine. It arises from the front of the aorta, imme- 
 
 * I have seen some splenic arteries not at all tortuous ; and at other times I hare found the curvatures so 
 decided that the lower part only of the curves came in contact with the pancreas. Why do these curvatures 
 exist ? It cannot be to accommodate the variations in the size of the spleen ; but is it to retard the now ol 
 the blood ? There is no proof of it ; indeed, the law which governs the existence of a tortuous condition ol 
 certain arteries is yet to he discovered. The caliber of the splenic artery is strictly proportioned to the size 
 of the spleen. Where it is strophied the artery is small ■ where hypertrophied, it becomes enormously enlarged 
 
ANGEIOLOGY. 
 
 diately below the coeliac axis, and very rarely from a common trunk with it. It is at 
 first situated behind the pancreas, and then passes vertically downward, between that 
 gland and the third portion of the duodenum, which is crossed at right angles by it, 
 and of which it forms the lower boundary {vide Duodenum) ; it at length reaches the 
 
 mesentery, opposite the point (a, fig. 202) 
 where that fold meets the transverse meso- 
 colon. Continuing its course within the sub 
 stance of the mesentery, and following its ad- 
 herent border, it describes a slight curve, with 
 the convexity directed to the left and the con- 
 cavity to the right side : gradually diminish- 
 ing in size as it advances, it proceeds to oppo- 
 site the ileo-caecal valve (i), and then becomes 
 so small that it can no longer be distinguished 
 from the branches given off from it. It fol- 
 lows, therefore, that the trunk (a b) of the su- 
 perior mesenteric artery corresponds with the 
 adherent border of the mesentery, with the 
 length of which it, as it were, agrees. 
 
 Collateral Branches. — While behind the pan- 
 creas, the superior mesenteric sends off pan- 
 creatic branches {k), which anastomose with 
 those derived from the hepatic and the splenic 
 arteries ; it rather frequently gives off the he- 
 patic, and it is then larger than the coeliac 
 axis. 
 
 In the mesentery, the superior mesenteric 
 gives off two sets of branches : one set ari 
 sing from its convexity, and forming the arter- 
 ies of the small intestine ; the other set from its 
 concavity, viz., the arteries of the great intestine, called the right colic arteries. 
 
 The arteries of the small intestine have received no particular name ; they are large 
 branches, directed obliquely downward and forward, all of which proceed parallel to 
 each other in the substance of the mesentery, towards the concave border of the small 
 intestine. Their number is irregular, and their size unequal : seven or eight of them 
 are at least equal in size to the radial artery, others are smaller ; the superior branches 
 are generally the largest. Their number is calculated at from fifteen to twenty. 
 
 After a course of about two or three inches, each of them bifurcates ; the branches 
 of the bifurcation separate from each other, and, curving into arches, inosculate with 
 the neighbouring branches. From the convexity of this series of arches, which is turn- 
 ed towards the intestine, a multitude of branches arise, which soon bifurcate, and form 
 anastomotic arches {d d d), which, as they are nearer the small intestine, describe a 
 curve of much greater extent in the mesentery than the first series. From the con- 
 vexity of this second series of arches a great many more branches arise than were given 
 off from the first series. Lastly, from the division of these branches a third series of 
 anastomotic arches is formed, which is still nearer the concave border of the intestine 
 than the second. 
 
 There are only three series of arches at the commencement and the termination of 
 the small intestine ; but in the middle there is a fourth, sometimes even a fifth. 
 
 From the convexity of the arches nearest to the small intestine arise two sets of ves- 
 sels, intended for the two halves of the cylindrical gut. Each of these sets of vessels 
 divides into superficial branches, which, ramifying beneath the peritoneum, form a super- 
 ficial network, and anastomose upon the convex border of the intestine ; and into deep 
 branches, which perforate in succession the muscular and cellular coats, and terminate 
 in an inextricable network in the mucous membrane. 
 
 The series of anastomotic arches formed by the divisions of the superior mesenteric 
 artery, not only regulate the current of the blood, but also enable a small number of 
 branches, occupying a very Umited space at the root of the mesentery, to supply branches 
 to so great an extent of surface as the entire length of the small intestine, which is from 
 fifteen to twenty-one feet. This spreading out of the vessels over a large surface will 
 be still better seen in the arrangement of the arteries of the great intestine. 
 
 The arteries for the great intestine, or the right colic arteries, are two or three in num- 
 ber, and are distinguished into the superior (e), middle (/), and inferior (A). They arise 
 from the concavity of the curve formed by the superior mesenteric artery, and pass from 
 the mesentery, in which they are enclosed at their origin, into the right lumbar meso- 
 colon. The superior is ascending, the middle horizontal, and the inferior descending ; 
 near the great intestine they bifurcate. The branches of the bifurcation anastomose, 
 and form very large arches, with their convexities turned towards the great intestine. 
 From these arches the intestinal branches take their origin directly, and divide into two 
 
 m 
 
THE INFERIOR MESENTERIC ARTERY, ETC. 
 
 511 
 
 Fig. 203. 
 
 sets of parallel ramifications, an anterior and a posterior, which, like those of the small 
 intestine, subdivide into the sub-peritoneal and the deep branches, and terminate in the 
 different coats of the intestine. Where the primary anastomotic arches are situated at 
 a certain distance from the intestine, for example, opposite the angles of bifurcation of 
 the arteries, or opposite the angles formed by the ileum with the caecum, and by the as 
 cending with the transverse colon, we find one, or even two, small arches filling up the 
 angular interval. 
 
 The upper branch (g) of the right superior colic artery (e, figs. 202, 203), which sup- 
 plies the right half of the arch of the colon, anastomoses with the upper branch of the 
 left colic artery Cf^fig- 203), which is derived from the inferior mesenteric (c). This re- 
 markable anastomosis between the superior and inferior mesenteric arteries has been 
 pointed out by anatomists as the most important anastomosis in the body. 
 
 The lowest branch of the right inferior colic artery (A, fig. 202) anastomoses with the 
 termination (J) of the superior mesenteric, which becomes exceedingly slender. This 
 right inferior colic, or ileo-colic artery (h), supplies the caecum, the ileo-caecal angle, and 
 the appendix vermiformis. 
 
 The Omphalo-mcsenteric Artery. — In the early periods of intra-uterine life, the superior 
 mesenteric artery gives off a branch, called the omphalo-mesentenc, which reaches the 
 umbilicus, passes out of the abdomen, traverses the entire length of the cord, and is dis- 
 tributed upon the umbilical vesicle. I have found this artery perfectly distinct in an 
 anencephalous fcEtus at the full term ; it is generally obliterated towards the end of the 
 second month of intra-uterine life. 
 
 The Inferior Mesenteric .Artery. 
 
 Dissection. — Turn the small intestines to the right side ; spread out the arch of the 
 colon, the right lumbar colon, and the sigmoid flexure ; remove the peritoneum, which 
 forms the inferior layer of the transverse mesocolon, and the right layer belonging to the 
 descending colon and sigmoid flexure. 
 
 The inferior mesenteric artery (m,fig. 199 ; c,fig. 203) is much smaller than the supe- 
 rior. It arises from the front" of the aorta, about 
 two inches above the bifurcation of that vessel. 
 It descends vertically in front of, and in contact 
 with the aorta, and then in front of the left com- 
 mon iliac artery. It is at first enclosed in the ili- 
 ac mesocolon, but afterward enters the meso-rec- 
 tum, where it divides into two branches, which 
 are named the superior hemorrhoidal {h, fig. 203). 
 In this course, the inferior mesenteric gives off 
 no branch on the right side ; on the left it gives 
 two, more frequently three branches, called the 
 left colic arteries (/), which are distributed in pre- 
 cisely the same manner as the right colic arteries. 
 I have already said that the upper division of the 
 left superior colic artery (/) inosculates with the 
 upper division (g) of the right superior colic (c). 
 Near the sigmoid flexure we find two, and some- 
 times three series of arches from the sigmoid 
 branch, so arranged that the last may reach the 
 intestine. 
 
 The superior hemorrhoidal arteries are distribu- 
 ted to the rectum, in the same manner as the other 
 intestinal arteries ; near the sphincter, they anas- 
 tomose with the middle hemorrhoidals, which 
 are derived from the internal iliac arteries. 
 
 The Spermatic Arteries — the Arteries of the Testicles in Man, and the Utero- 
 
 ovarien in Woman. 
 
 Dissection. — Remove carefully the mesentery and the peritoneum. Follow these ar- 
 teries, in man, through the inguinal passages imbedded in the substance of the sper- 
 matic cord, down to the testicle and the epididymis ; and in woman, follow them into the 
 substance of the broad ligament as far as the ovaries on one side, and on the other, as 
 far as the bottom and the body of the uterus. To inject perfectly these arteries to their 
 termination, recourse must be had to very penetrating liquids, or, what is better, to par- 
 tial injections. 
 
 The spermatic arteries (o o,fig. 198 ; ff,fig. 199) are distributed to the testicles in the 
 male, and to the ovaries in the female. 
 
 They are two in number, and are as variable in their origin as they are regular in their 
 course and distribution. 
 
 Their origin is remarkably distant from their termination ; an unsatisfactory attempt 
 
 ® 
 
612 ANGEIOLOGY. 
 
 has been made to explain this circumstance by referring to the situation of the testicle in 
 the foetus. 
 
 Varieties of Origin. — These arteries generally arise from the front, sometimes from 
 the side of the aorta, below the corresponding renal artery, rarely above it, and still 
 more rarely from the renal itself It is rather rare for the right and left spermatics to 
 come off at the same heights. I have seen the right spermatic artery arise below the 
 renal, and the left by the side of the inferior mesenteric* 
 
 Whatever may be their origin, these arteries pass directly downward. Sometimes 
 they come off at a riglit angle, and then curve downward, so as to descend almost ver- 
 tically upon the sides of the spine, behind the peritoneum, in front of the corresponding 
 psoas muscle and ureter, and on the inner side of the spermatic veins. The right sper- 
 matic artery is in relation with the vena cava inferior, and almost always passes in front, 
 but sometimes behind it ; the artery of the left side is situated behind the sigmoid flex- 
 ure of the colon. On both sides, having reached the side of the pelvis, the artery is sit- 
 uated on the inner side of the psoas, in front of the external iliac artery, and is then dif- 
 ferently distributed in the two sexes. 
 
 Li the male {f, fig- 199), it enters the abdominal orifice of the inguinal canal, along 
 which it proceeds, and, together with the vas deferens and the spermatic veins, forms the 
 spermatic cord ; it escapes from the canal, and, at a greater or less distance from the 
 ring, divides into two branches, one of which enters the head of the epididymis, while 
 the other, the testicular, penetrates the testicle at its upper border, and is then distribu- 
 ted as already described (see Testicles). 
 
 In the female, the ovarian arteries (o o,fig. 198), which are much shorter than the 
 spermatics of the male, dip into the pelvis, reach the upper border of the ovaries, supply 
 them, and also the Fallopian tubes, with a great number of branches, and terminate 
 upon the sides of the uterus, by anastomosing freely with the uterine arteries (« w').+ 
 
 The ovarian arteries are distributed more to the uterus than to the ovary, as may be 
 proved by the post mortem examination of the body of a pregnant or puerperal female ; 
 for it is then seen that the ovarian arteries also become largely developed as well as the 
 uterine, and that the branches sent to the uterus are enormous in comparison with those 
 given off to the ovaries. 
 
 The ovarian arteries are very tortuous, especially opposite the brim of the pelvis ; 
 they are quite as much convoluted as the uterine arteries. 
 
 The Renal or Emulgent Arteries. 
 
 Dissection. — The renal arteries are prepared after the intestines, the peritoneum, the 
 renal adipose tissue, and the numerous nervous filaments by which the arteries are sur- 
 rounded, have been removed. 
 
 The renal or emulgent arteries {,e e,fig. 199) arise at right angles from the side of the 
 aorta, above the inferior mesenteric : the left renal artery often arises a little higher 
 than the right, doubtless on account of the size of the liver. These arteries are very 
 large in comparison to the kidney, for they are nearly equal in size to the cceliac axis, 
 or the superior mesenteric ; they are remarkable for their transverse, and, generally, 
 straight direction ; for their shortness ; and, lastly, for their numerous varieties. These 
 we shall now mention. 
 
 Varieties as to Number. — There is generally one for each kidney, but frequently there 
 are two, three, or four. Varieties as to Origin. — Not uncommonly the renal arteries arise 
 from the aorta lower down than usual, or even from the common iliac or the internal 
 iliac. The two latter modes of origin are scarcely observed, excepting when the kidney 
 is displaced, and occupies either the ihac fossa or the cavity of the pelvis. In a case 
 which I recently examined, the kidney occupied the cavity of the pelvis, and there were 
 two renal arteries, one of which arose from the aorta at its bifurcation, and the other 
 near the inferior mesenteric. Lastly, I should add that Meckel has seen the two renal 
 arteries arise by a common trunk from the front of the aorta. Varieties in Direction.— 
 When two renal arteries arise from the same side, or when one divides into two branch- 
 es, I have found them, in several cases, twisted spirally round each other, like the um- 
 bilical arteries. Varieties as to Division. — The renal artery sometimes divides immedi- 
 ately after its origin ; and then one of the branches, separating itself from the others, 
 proceeds to one or other extremity of the kidney. Such a mode of division leads to 
 those cases in which there is more than one artery. 
 
 Relations. — The renal arteries are covered by the peritoneum and the corresponding 
 renal veins ; they are surrounded by a quantity of adipose cellular tissue, and they rest 
 behind upon the bodies of the vertebrae. The right renal artery is also covered by the 
 inferior vena cava. In one case, where there were two renal arteries on the right side, 
 one of these was in front, and the other behind the vena cava. 
 
 * It IS not micommon to meet witn two spermatic artenes on one siae 
 
 t We know that the development of the uterus, (luring the first five months a& pregnancy, takes place al- 
 most exclusively at the expense of the body, and that the neck of the uterus be^ns to be developed from the 
 fifth to the sixtii month. I have seen some diseases of the uterus in which a sort of independence might have 
 been traced between the neck and the body of the womb. 
 
THE CAPSULAR ARTERIES, ETC. 618 
 
 Collateral Branches. — The renal arteries give off some small twigs to the supra-renal 
 capsules, which are called the inferior capsular or supra-renal, and also some small branch- 
 es to the adipose tissue which covers the kidney, and to its proper cellular coat. 
 
 Terminal Branches. — At the hilus of the kidney, the renal artery divides into three or 
 tour branches, all of which enter the hilus, between the pelvis of the ureter, which is 
 behind, and the branches of the renal vein, which are in front. The arteries subdivide 
 in the kidney so as to form a network at the Umits between the tubular and cortical sub- 
 stances. (See Kidney.) A very few of the branches from this network proceed to the 
 tubular substance, almost all of them being distributed to the cortical substance. Most 
 anatomists have remarked the facility with which even coarse injections pass from the 
 renal arteries into the veins and ureters. 
 
 The Middle Supra-renal, or Capsular Arteries. 
 
 The middle supra-renal arteries {s s,fig. 199), so named in contradistinction to the supe- 
 rior vessels of the same name, derived from the diaphragmatic and the inferior, pro- 
 ceeding from the renal, are of large size in comparison with the organ to which they are 
 distributed. They arise from the sides of the aorta, above the renal, supply twigs to the 
 surrounding fat, and to the pillar of the diaphragm, run along the concave border of the 
 corresponding supra-renal capsule, give off anterior and posterior branches, which enter 
 the furrows on the surface of that organ, and penetrate and ramify in its interior. 
 
 ARTERIES ARISING FROM THE ARCH OF THE AORTA. 
 Enumeration and Varieties. — The Common Carotids. — The External Carotid — the Superior 
 Thyroid — the Facial — the Lingual — the Occipital — the Posterior Auricular — the Parotid 
 — the Ascending Pharyngeal — the Temporal — the Internal Maxillary. — The Internal Ca- 
 rotid — the Ophthalmic — the Cerebral Branches of the Internal Carotid. — Summary of the 
 Distribution of the Common Carotids. — Artery of the Upper Extremity. — The Brachio-Ce- 
 phalic. — The Right and Left Subclavian^ — the Vertebra} and its Cerebral Branches, with 
 Remarks on the Arteries of the Brain, Cerebellum, and Medulla — the Inferior Thyroid — 
 the Supra-scapular — the Posterior Scapular — the Internal Mammary — the Deep Cervical 
 — the Superior Intercostal. — The Axillary — the Acromio-thoracic — the Long Thoracic — the 
 Sub-scapular — the Posterior Circumflex — the Anterior Circumflex. — The Brachial and its 
 Collateral Branches. — The Radial, its Collateral Branches, and the Deep Palmar Arch. — 
 The Ulnar, its Collateral Branches, and the Superficial Palmar Arch. — General Remarks 
 on the Arteries of the Upper Extremity. 
 
 Three arterial trunks, intended to supply the head and the upper extremities, take 
 their origin from the arch of the aorta. Proceeding in the order in which they arise, i. e., 
 from right to left, they are the innominate or brachio-cephalic {e,fig. 198), which soon sub- 
 divides into the right common carotid (/) and right subclavian (g), the left common carotid (f) 
 and the left subclavian (g). 
 
 The direction of that portion of the arch of the aorta which gives origin to these arter- 
 ies is such, that they are arranged one after the other upon a plane which slopes down- 
 ward, backward, and to the left ; so that the trunk of the innominate artery lies almost 
 immediately behind the sternum, while the left subclavian is near the vertebral column. 
 Varieties. — These three arteries present numerous varieties in their origin, all of which 
 appear to me to be referrible to the three following heads : varieties by approximation or 
 fusion, varieties by multiplication, and varieties by transposition of their origins. In 
 many cases, several of these kinds of varieties may coexist.* 
 
 Varieties by Approximation or Fusion of Origins. — Sometimes the left common carotid 
 becomes closely approximated to the brachio-cephalic trunk ; and this condition leads us 
 to the not very uncommon variety in which these two vessels arise by a common trunk, t 
 Again, two brachio-cephalic trunJjs may be given off from the arch of the aorta, one on 
 the right, the other on the left side.t Of these two trunks which arise from the aorta, 
 the first, which is the most voluminous, gives origin to the two carotid arteries, and to 
 the right subclavian ; the second, which is the smallest, gives origin to the left subcla- 
 vian. The greatest amount of variety of this kind is observed in the case where the 
 three branches which usually arise from the arch are united into one common trunk, 
 which forms an ascending aorta. In this case, there is no arch of the aorta ; the aorta, 
 
 * [A variety, affecting merely the situation of the three primary vessels upon the arch, is noticed by Pro- 
 fessor R. Quain {Operacit.). It consists in those vessels arising to the riglit of their usual position, t. e., near- 
 er to the origin of the aorta.] 
 
 t I have often seen these three branches, viz., the brachio-cephalic trunk, the left primitive carotid, and the 
 left subclavian, arising by tlie side of each other, so that their three orifices were only separated, as it were, 
 by a spur. 
 
 i This variety, which, together with the preceding, constitutes the normal state of some animals, seems, 
 moreover, th& reproduction of the normal disposition of the venous system, in which there are two cephalic 
 venous trunks, one right, the other left, which unite for the purpose of forming the superior vena cava. Meck- 
 el, I believe, was the first to remark that certain anomalies of the arterial system might be attributed to the 
 normal disposition of the venous system. — (See the excellent article of Dr. Rendu, Memoir on the History of 
 Arterial Anomalies, Gazette Medicate, 1842, vol. x., p. 129.) 
 
 Ttt 
 
514 ANGEIOLOOY. 
 
 immediately after its origin, is divided into ascending and descending. This arrange- 
 ment is normal in the ox, the horse, the sheep, the goat, and some other animals.* 
 
 Varieties by Multiplication of Origin. — Sometimes the two common carotids arise sep- 
 arately in the interval between a right and a left subclavian, a condition that leads us to 
 the case in which the two carotids arise by a common trunk between the separated sub- 
 clavians. Again, the left vertebral artery may arise directly from the aorta, between 
 the left carotid and subclavian ; this is very common : or the two vertebrals, the two 
 carotids, and the two subclavians may all arise separately ; or the inferior thyroid, or the 
 thyroid of Neubauer, from the name of the anatomist who first described this variety, 
 may arise directly from the curvature of the aorta ; lastly, the right internal mammary 
 and the left vertebral may arise directly from the arch of the aorta. 
 
 Varieties by Transposition or Inversion of Origin. — The brachio-cephalic trunk is some- 
 times found on the left side instead of the right ; still more frequently the right subcla- 
 vian arises separately below the left subclavian, and then passes upward and to the 
 right side, most commonly behind the trachea and oesophagus, but sometimes between 
 these two canals. Again, the trunks arising from the arch of the aorta have been seen 
 to be given off in the following order : a single trunk for both common carotids ; then 
 the left subclavian ; and, lastly, the right subclavian, which arose from behind the arch 
 of the aorta, and passed as in the preceding case. A fifth variety consists in a combi- 
 nation of the variety by transposition either with the variety by fusion or with the vari- 
 ety by multiplication. 
 
 The Common Carotid Arteries. 
 
 Dissection. — Dissect the anterior cervical region, preserving all the parts in relation 
 to the vessels. In order to see the tlioracic portion of these arteries, remove the upper 
 part of the sternum. 
 
 The primitive or common carotid arteries {ff, jig. 198 ; a, fig. 204) are the arteries of 
 the head. Their limit above is marked by the upper border of the thyroid cartilage, op- 
 posite which they divide into the external and internal carotids. + 
 
 They are two in number, distinguished as the right and left : they differ as to their 
 origin, their length, and their directions ; thus, on the left side, the common carotid ari- 
 ses directly from the aorta ; on the right, it arises from a trunk common to it and to the 
 subclavian, viz., the innominate, or brachio-cephalic artery {e,fig. 198). As the brachio- 
 cephalic and the left common carotid are given off from the aorta nearly at the same 
 level, it follows that the left common carotid is longer than the right by the entire length 
 of the brachio-cephalic. 
 
 It follows, also, from the obliquity of the arch of the aorta, that the left common ca- 
 rotid is placed much deeper than the right at its origin ; but, in the cervical region, the 
 two carotids are upon the same plane. 
 
 They pass somewhat obliquely upward and outward immediately after their origin, 
 but they are directed vertically and parallel to each other in the cervical region. t The 
 interval between them is occupied by the trachea and the oesophagus below, and by the 
 larynx and phaiynx above. Their course is straight, and without any winding. Their 
 diameter is uniform throughout, a circumstance which is connected with the absence 
 of any collateral branches. The caliber of these arteries is relatively larger in man than 
 in other animals ; and this has reference to the greater size of his brain. I have not ob- 
 served any difference in diameter between the right and left common carotids. 
 
 As about one inch in length of the left common carotid lies in the thorax, its relations 
 must be separately studied in that situation. 
 
 Relatians of the Thoracic Portion. — In front, with the left subclavian vein, and the ster- 
 no-hyoid and sterno-thyroid muscles, which separate it from the sternum ; behind, with 
 the trachea and oesophagus, and with the left subclavian and left vertebral arteries ; on 
 the outside, with the pleura or the left wall of the mediastinum ; on the inside, with the 
 brachio-cephalic trunk, from which it is separated by a triangular interval, in which the 
 trachea is visible. 
 
 Relations of the Cervical Portion. — These are the same for both arteries. In front, 
 each common carotid is covered below by the stemo-mastoid, and more immediately by 
 the sterno-hyoid, sterno-thyroid, and omo-hyoid muscles, the latter of which crosses 
 the artery obliquely.^ In its upper half it corresponds to the platysma myoides, which 
 separates it from the skin. The cervical fascia, the superior thyroid vein, and the de- 
 scendens noni, a branch of the hypoglossal nerve, are in more immediate relation with 
 
 * Some anomalies of the arterial system of man may be in some measure explained from the normal state 
 of the arterial system of certain animals ; but the number of such cases is extremely limited. I do not know 
 whether any one hai ever thought of applying- to these anomahes the rule of the arrest of development, wliich 
 some have lately made to play such an exaggerated part in the theory of the vices of conformation. 
 
 t [The common carotid has been seen to divide above the os hyoidos, also opposite the thyroid cartilage, 
 and even low down in the neck.] 
 
 t [In consequence of the larynx being wider than the trachea, the common carotids arc not quite parallel 
 in the neck, but are somewhat farther apart above than below.] 
 
 I) In order to omit nothing, I should say that the common carotid is crossed obliquely by a branch which i» 
 given off from the superior thyroid artery to the stemo-niastoid muscle. 
 
THE EXTERNAL CAKOTID ARTERY. 
 
 515 
 
 It. The most important of these relations is that with the sterno-mastoid, which, in a 
 surgical point of view, may be regarded as its satellite muscle. Behind, the common 
 carotid is the vertebral column, from which it is separated by the pre- vertebral muscles, 
 the great sympathetic nerve, and below by the recurrent nerve and inferior thyroid 
 artery.* On the itiside, it is in relation with the trachea, oesophagus, larynx, and thy- 
 roid gland, which passes in front of the artery when larger than usual ; on the outside 
 of the artery is the internal jugular vein. The pneumogastric nerve lies at the back, 
 between the artery and vein. The common carotids are also surrounded by much loose 
 cellular tissue, and by some lymphatic glands. 
 
 The left common carotid is in more direct relation with the oesophagus than the ar- 
 tery of the right side. 
 
 The common carotids give off no branch during their course : nevertheless, it is not 
 very rare for this artery to give off the inferior thyroid artery, or a supernumerary branch 
 known as the middle thyrmdA Neabauer has seen the common carotid give off a thy- 
 roid artery, and the internal mammary of the right side. 
 
 Terminal Branches. — Having reached the upper border of the thyroid cartilage, at a 
 variable height, according to the subject, the common carotid divides into two branches, 
 called the external and internal carotids, which, by no means a common arrangement, do 
 not leave each other at an acute angle, but remain in contact, and even frequently be- 
 come crossed before they separate. The point of division is also remarkable for a sort 
 of ampulla or dilatation, which the primitive carotid exhibits. Sometimes the primitive 
 carotid bifurcates much sooner than usually. Morgagni relates a case in which the 
 bifurcation took place at the distance of an inch and a half from the origin of the ar- 
 tery. Sometimes the primitive carotid does not terminate in a bifurcation. In such a 
 case, all the branches given off by the external carotid arise successively from the prim- 
 itive carotid, which penetrates the cranium and terminates as the internal carotid. 
 
 The External Cakotid Artery. 
 
 Dissection. — Prolong the incision made for exposing the conmion carotid as far as th,e 
 neck of the condyle of the lower jaw. Dissect carefully the styloid muscles and the diga!s- 
 tricus, and cautiously separate the artery from the surrounding tissue of the parotid gland . 
 
 The external or superficial carotid artery {h,fig. 204) is, in a great measure, intitw ! 
 
 Fig. 204. 
 
 for the face, and has, therefore, been 
 called the facial carotid by Chaussier. 
 It arises from the conunon carotid, 
 forming one of its two divisions, and 
 extends as far as the neck of the con- 
 dyle of the lower jaw, where it termi- 
 nates by dividing into the temporal and 
 internal maxillary arteries. 
 
 The origin of this artery is remark- 
 able for being situated on the inner 
 side of the internal carotid. It as- 
 cends vertically as high as the digas- 
 tricus, and passes under that muscle ; 
 it is then directed a little backward 
 and outward, leaves the vertebral col- 
 umn, reaches the angle of the lower 
 jaw, and again becomes vertical as it 
 proceeds upward to the neck of the 
 condyle, opposite to which it termi- 
 nates. It is very slightly tortuous in 
 the adult, and in the infant is almost 
 straight. In the adult it is nearly equal 
 in size to the internal carotid, but it is 
 
 much smaller in young subjects. It diminishes rapidly in diameter, on account of thn 
 number of branches given off from it, so that at its termination it is scarcely one tliird 
 Its origmal size. Sometimes it divides immediately into a sort of bunch of arterial ves- 
 sels ;in other cases its branches arise in succession from the common carotid, which is 
 then directly continuous with the internal carotid. ± 
 
 J\.^ l^^^^J °^ relations which it is important to know m a surgical point of view is the relation which often 
 exists behind, between the right primitive carotid and the trachea. Where this anomaly eiists, the brachio- 
 cephalic trunk arises a Lttle more to the left side than usually «:»J»t», 
 
 t This supernumerai7 artery arises at different elevations, 'in a case which has been communicated to me 
 .IJa ^Tv't i '^^ '^'^'^^^ °l s"P?"iumerary thyroid artery was given off by the right primitive ca- 
 
 rotid at the distance of a centrmeter from the innominata. It passed up in a straight line into the gland, where 
 nfT.i? i ,1' a"|=""'5t°'n°s'='i freely with the superior and inferior thyroidian arteries on each side. The right 
 inferior thyjoidian artery was not half as voluminous as usual. Mr. Dubreuil, who teaches anatomy with so 
 much talent at Montpelier, has communicated to me several arterial anomalies, which are to be inserted in a 
 professional work that he is prnparing on that subject in a surgical point of view 
 
 » It IS doubtless on account of the numerous branches given off by the external carotid that several ancient 
 
516 ANGEIOLOGY. 
 
 Relations. — It is superficial at its origin, like the upper part of the common carotid, 
 and, like it, is merely separated from the skin by the platysma myoides ; but it then 
 dips into the supra-hyoid region, below the digastricus, the stylo-hyoideus, and the hypo- 
 glossal nerve.* Higher up it is situated deeply in the parotid excavation, surrounded 
 on all sides by the tissue of the parotid gland, which, on this account, cannot be entire- 
 ly extirpated without wounding the vessel. 
 
 Collateral Branches. — These are six in number, and are arranged into three sets, viz., 
 an anterior set, consisting of the superior thyroid, the facial, and the lingiud ; a posterior, 
 including the occipital and the auricular ; and an internal set, formed by one vessel, the 
 inferior, or ascending pharyngeal. 
 
 The terminal branches are two in number, the superficial temporal and the internal max- 
 
 The Superior Thyroid Artery. 
 
 The superior thyroid artery (d. Jig. 204) belongs both to the larynx and the thyroid 
 gland. It is the first branch given off from the external carotid ; it rather frequently 
 arises opposite the bifurcation of the common carotid, which in this case would seem to 
 divide into three branches. In some cases it arises directly from the common carotid ; 
 at other times it has been seen to come off by a conmion trunk with the lingual. It is 
 always of considerable size, but varies in this respect, maintaining either a direct rela- 
 tion to the size of the thyroid body, or an inverse proportion to that of the other thyroid 
 arteries. 
 
 Direction. — It is at first airected horizontally forward and inward ; but it almost im- 
 mediately bends, and proceeds vertically to the upper end of the corresponding lobe of 
 the thyroid gland, in which it terminates. 
 
 Relations. — It is superficial at its origin, where it is covered only by the skin and the 
 platysma ; it then dips under the omo-hyoid, sterno-hyoid, and sterno-thyroid muscles, 
 and it is also covered by the cervical fascia and the superior thyroid veins. This artery 
 furnishes several collateral branches, viz., the superier laryngeal, the inferior laryngeal or 
 crico-thyroid, and the sterno-mastoid branch, t 
 
 The Superior Laryngeal Branch. — This (c) comes off from the thyroid, at the point 
 where the latter changes its direction ; sometimes it arises from the external carotid. 
 In certain cases it is so large that it may be regarded as formed by a bifurcation of the 
 thyroid. In one case where it was wanting on the left side, I found it replaced by the 
 right superior thjnroid, which was almost double its usual size. This artery passes 
 transversely inward between the thyro-hyoid muscle and the membrane of the same 
 name, which it perforates along with the superior laryngeal nerve ; having reached the 
 cellular tissue behind this membrane, it divides into two branches, an ascending, or epi- 
 glottid branch, which passes upon the side, then in front of the epiglottis, and ramifies 
 upon it ; and a descending, or laryngeal branch, properly so called, which passes behind 
 the thyroid cartilage, between it and the thyro-arytenoid muscle, and is distributed upon 
 the muscles and mucous membrane of the lar)Tix. Not unfrequently the superior laryn- 
 geal branch enters the larynx through a foramen existing in the thyroid cartilage in 
 some subjects. 
 
 The Inferior Laryngeal or Crico-thyroid Branch. — This arises from the internal termina- 
 ting branch of the superior thyroid artery ; it is more remarkable for its constant presence 
 than for its size. It is sometimes wanting on one side, but it is then replaced by the 
 superior thyroid artery of the other side. It passes transversely inward, in front of the 
 crico-thyroid membrane, along the lower border of the thyroid cartilage, and inosculates 
 with the branch of the opposite side. From the arch thus formed twigs proceed, which 
 perforate the crico-thyroid membrane, and ramify in the muscles and the mucous mem- 
 brane of the larynx. 
 
 It is not uncommon to find the inferior laryngeal artery dividing into two branches : 
 one superficial and transverse, the other ascending, which passes up behind the thyroid 
 cartilage. 
 
 M. Chassaignac has exhibited, at the Anatomical Society, a preparation, in which the 
 trunk of the superior thyroid artery, instead of giving off the inferior laryngeal branch, 
 passed itself transversely over the crico-thyroid ligament. 
 
 I'.ie Sterno-mastoid Branch. — This is constant, but of variable size. It comes off from 
 the superior thyroid, a little below the superior laryngeal, and passes downward to reach 
 the deep surface of the sterno-mastoid muscle, to which it is distributed. 
 
 Terminal Branches. — Having reached the gland, the thyroid artery divides into three 
 branches, viz., one which passes between the gland and the trachea ; another, which 
 
 authors have not described this vessel as a particular artery, but have contented themselves with describing 
 the branches which it gives off. 
 
 * [It crosses over the styloid process, the stylo-glossus and pharjmgeus muscles, and the glosso-pharyngeal 
 nerve, which lie between it and the internal carotid.] 
 
 t [The first branch is usually a small one, named the hyoid, which arises opposite the great comu of the 
 OS hyoides, passes inward on the thyro-hyoid membrane, and anastomoses with the vessel of the opposite 
 side.} 
 
THE FACIAL AHTERY. 5X7 
 
 proceeds along the outer border of the corresponding lobe ; and a third, which runs 
 along the inner border, and anastomoses in the median line with the corresponding 
 branch of the opposite side. It is this vessel which sometimes gives off the inferior 
 laryngeal.* 
 
 The Facial, the Labial, or External Maxillary Artery. 
 
 Dissection. — Let the head fall backward by means of a billet placed under the neck, 
 and incline it towards the side opposite to that on which the artery is to be laid bare ; 
 dissect carefully the digastricus and stylo-hyoid muscles, which must be cut superiorly 
 at their origin from the styloid process ; dissect the sub-maxillary gland, then the mus- 
 cles of the ia.ce, avoid injuring the numerous branches which may come under the scalpel. 
 
 The facial artery (/, figs. 204, 206), so called from its distribution, is given off from 
 the front of the external carotid, a little above the os hyoides : it is so large in some 
 subjects that it seems to be formed by a bifurcation of the extemcil carotid. It pro- 
 ceeds in a tortuous course from below upward, and then from behind forward, along 
 a groove formed in the sub-maxillary gland. After leaving this groove, it passes verti- 
 cally upward, crosses the body of the lower jaw at right angles in front of the masseter 
 muscle, becomes oblique, arrives near the conunissure of the lips, reaches the furrow 
 between the ala nasi and the cheek, and terminates near the inner angle of the eye, by 
 anastomosing with one of the branches of the ophthalmic, and with the infra-orbital ar- 
 tery. The termination of the facial artery is subject to numerous individual varieties. 
 The vessel is also remarkable for being extremely tortuous, a condition which is con- 
 nected with the mobility of the parts supplied by this artery, which runs in succession 
 over the supra-hyoid, the inferior maxillary, the buccal, and the nasal regions. 
 
 Relations. — In the supra-hyoid region the facial artery is covered by the digastric and 
 stylo-hyoid muscles ; then, along the base of the jaw, it is in relation with the outer sur- 
 face of the sub-maxillary gland, and is separated from the skin by the platysma and a 
 great number of lymphatic glands. In the facial region, the artery is covered below by 
 the platysma, higher up by the triangularis oris and the zygomaticus major, and in all the 
 rest of its extent by a greater or less quantity of fat, which separates it from the skin ; 
 it lies upon the inferior maxilla, against which it may be compressed in front of the 
 masseter, also upon the buccinator, the orbicularis oris, the levator communis, and the 
 levator proprius. 
 
 Collateral Branches. — The following branches are given off by the facial artery in the 
 supra-hyoid region. The inferior palatine, a small branch which is sometimes derived 
 from the external carotid, or from the ascending pharyngeal artery, passes up behind 
 [or between] the stylo-glossus and stylo-pharyngeus muscles, to which it furnishes some 
 branches, gains the side of the pharynx, and is distributed to the tonsil, which it covers 
 with its ramifications, and also to the velum palati and the pillars of the fauces, oppo 
 site which it anastomoses with several branches of the ascending pharyngeal artery. 1 
 have seen the palatine branch of the facial extremely large, and taking the place of the 
 tonsillar and palatine branches of the ascending pharyngeal artery. 
 
 The sub-mental branch (g,fig. 204) runs along the inner side of the lower border of the 
 ramus of the jaw, between the digastricus and mylo-hyoideus, passes upward in front of 
 the bone, on the outer side of the anterior attachment of the digastricus, and ramifies in 
 the skin and muscles of the chin, anastomosing with the ramifications of the inferior 
 dental artery. Sometimes the sub-mental divides into two or three branches, all of which 
 terminate in the same manner, after perforating the digastric muscle. 
 
 Branches for the Sub-maxillary Gland. — These are three or four in number, and are 
 large in proportion to the organ which they supply. 
 
 The Pterygoid Branch. — This is a small branch which passes into the internal ptery- 
 goid muscle. 
 
 The collateral branches of the /aciaZ region are divided into external and internal. The 
 external branches ramify in all the muscles and integuments of the cheek, and anastomose 
 freely with the transverscdis faciei, a branch of the superficial temporal : the most re- 
 markable of these branches are the two given to the masseter and buccinator muscles. 
 
 Among the internal branches, besides a number of small twigs which have received no 
 names, we remark the following . 
 
 The inferior coronary or labial artery (h), which is given off from the facial, a little be- 
 low the commissure of the lips ; it pursues a serpentine course in the substance of the 
 lower lip, between the muscular and glandular layers, at a greater or less distance from 
 the free border of the lip, and anastomoses, in the median line, with the corresponding 
 vessel of the opposite side. I have seen this artery occupy the lower or adherent border 
 of the lower lip until it reached the median line, when it ascended vertically to the free 
 border, wh'ere it divided into two equal branches, which passed, horizontally, one to the 
 
 * I have seen the branch winch runs along^ tlie inner border of the thyroid gland pass transversely to the 
 left side, above and at a certain distance from this border ; having reached the median line, it proceeded ver- 
 tically downward, in front of the crico-thyroid ligament, to the middle of the thyroid gland, where it gave off 
 the right and left inferior laryngeal branches. The left thyroid was very small, and only furnished the ex- 
 ternal branch for the thyroid gland. 
 
5f8 
 
 ANGEIOLOGY. 
 
 right and the other to the left, in order to form a second coronary artery, smaller than 
 the first. 
 
 The superior coronary, or labial, arises opposite the commissure, passes in the upper 
 lip between the muscular and glandular layers, and inosculates, in the median line, with 
 the vessel on the opposite side. Branches are given off from this arch to the mucous 
 membrane, the gums, the muscles, and the skin. One branch only of this artery requires 
 a special description ; it is known by the name of the artery of the septum nasi (z). It 
 comes off, in the median line, by one, two, and sometimes three branches, which pass 
 vertically upward, and then horizontally beneath the skin, covering the under surface of 
 the septum as far as the tip of the nose, where they anastomose with the artery of the ala. 
 
 The artery of the ala nasi, or lateral artery of the nose (/), which is very often the ter- 
 mination of the facial, divides into two branches : a small one, that runs along the lower 
 border of the cartilage of the ala, and anastomoses with the anery of the septum ; and a 
 larger one, that runs along the upper convex border of that cartilage. A small branch pen- 
 etrates into the interior of the nares, between the cartilage and the opening of the nostril. 
 
 Termination of (he Facial Artery. — The facial artery having become extremely slender, 
 sometimes terminates, under the name of the angular branch (m), upon the side of the 
 nose, by anastomosing with the nasal branch of the ophthalmic, and with the infra-orbit- 
 al. At other times its termmation is formed by the artery of the ala of the nose, or by 
 the superior coronary of the lip, or even by the inferior coronary. I have seen i'l termi- 
 nate in the artery of the septum. We seldom find the facial arteries of both sides ahke. 
 Sometimes there is merely a trace of one, while the other is very much developed, and 
 supplies by itself alone all the nasal and labial branches. No artery varies more thai? 
 the facial, both in size and extent of distribution. 
 
 Its anastomoses with the inferior dental and infra-orbital arteries, branches of the in 
 ternal maxillary, as well as those with the ophthalmic, a branch of the internal carotid, 
 should be particularly noticed. 
 
 The Lingtial Artery. 
 Dissection. — Cut the hyoidian insertions of the mylo-hyoid muscle, which is to be 
 turned up from below upward ; saw the inferior maxillary bone, either at the symphysis 
 or on each side of it. Hook the tongue and draw it out of the mouth, and maintain it in 
 that position while you follow the artery as situated at its inferior surface. 
 
 The lingual artery {n, figs. 204, 205), which is very large considering the size of the 
 Fig. 205. organ to which it is distributed, comes off from the front of the ex- 
 
 ternal carotid, between the facial and the superior thyroid, and often 
 by a common trunk with the facial ; it passes at first obliquely up- 
 ward, and then transversely inward and forward, along the upper 
 margin of the corresponding great cornu of the os hyoides : oppo- 
 site the lesser cornu of that bone it changes its direction, and runs 
 in a serpentine course from behind forward, in the substance of the 
 tongue as far as the apex, where it terminates by anastomosing 
 with the artery of the opposite side ; in the latter part of its course 
 it is named, we know not why, the ranine artery Q, fig. 205 ; rana, 
 a frog). Its remarkably tortuous course is connected with the lia 
 bility of the tongue to undergo great changes in its relative dimen- 
 sions. 
 
 Relations. — It is deeply seated, at its origin, under the digastric 
 '* and stylo-hyoid muscles and the hypo-glossal nerve ; opposite the 
 OS hyoides (at n. fig. 205) it is situated between the hyo-glossus (the nerve passing over 
 that muscle) and the middle constrictor of the pharynx : in the substance of the tongue 
 it is placed between the genio-hyo-glossus and the lingaalis, and is accompanied by the 
 lingual branch of the fifth nerve ; consequently, it occupies the inferior surface Of the 
 tongue. 
 
 Collateral Branches. — A small transverse branch, the hyoid (e), forms an anastomotic 
 «irch with the vessel of the opposite side, upon the body of the os hyoides, between the 
 genio-hyo-glossus and the genio-hyoideus. 
 
 The dorsal artery of the tongue (/), generally small and diflicult to demonstrate; it 
 arises opposite the great cornu of the os hyoides, ascends upon the lateral border of the 
 tongue, near the anterior pillar of the fauces, to which it gives branches, then passes 
 forward and inward, and giving several epiglottid branches, which anastomose with 
 those of the opposite side, is finally distributed to the caliciform papillae. In the whole 
 of its course, this artery lies immediately beneath the mucous membrane. 
 
 The sub-lingual artery (i) is large enough to be regarded by some as resulting from the 
 bifurcation of the lingual, which, according to them, takes the name of raninal only after 
 it has furnished the sub-lingual branch. It arises as often from the facial, by a common 
 trunk with the sub-mental, as from the lingual itself It passes horizontally forward be- 
 tween the mylo-hyoideus, which separates it from the sub-mental, and the genio-hyo- 
 glossus, and, in company with the Warthonian duct, runs along the lower border of the 
 
THE OCCIPITAL ABTERY, ETC. 519 
 
 •Qb-Iingual gland, to which it furnishes numerous twigs, and then divides into two 
 branches : the larger, or the artery of the franum, anastomoses, in an arch, with the ves- 
 sel of tlie opposite side above thefraenum ; while the smaller, or ascending branch, pass- 
 es upon the sides of the symphysis menti, and sends twigs into the several incisor fora- 
 mina, situated behind the teeth of the same name. It is this artery of the fraenum, not 
 the ranine artery, which is liable to be wounded in division of the fraenum. Not unfre- 
 quently the sub-lingual artery gives off a superficial branch, which passes through the an- 
 terior belly of the digastricus, and ramifies upon the region of the chin, like the analo- 
 gous branches of the sub-mental. 
 
 Lastly, in the substance of the tongue, the lingual artery gives off superior, internal, and 
 external branches, which supply the muscles and the papillary membrane oif that organ. 
 
 The Occipital Artery. 
 
 Dissection. — Detach the sterno-mastoideus and the splenius at their superior inser- 
 tions. To uncover more completely this artery, which is deeply situated between the 
 mastoid process and the transverse process of the atlas, cut with a chisel or saw the 
 mastoid process at its base, turning it from above downward with the muscles which are 
 inserted into it ; cut the styloid process at its base, and turn the styloid muscles down. 
 Remove carefully the skin of the occipital region, so as to enable you to follow the sub- 
 cutaneous branches. 
 
 The occipital artery (o o, fig. 204), which is distributed to the posterior region of the 
 head, is smaller than the three branches of the external carotid already described. It 
 arises from the back of the external carotid, on a level with the lingual or the facial, 
 sometimes immediately below the parotid gland : it passes obliquely upward and back- 
 ward, as high as the apex of the mastoid process ; it then passes horizontally backward, 
 and on the inner side of the splenius muscle, divides into two ascending branches : one 
 external, which immediately bends upward ; the other internal, which is continued hori- 
 zontally, and is then reflected vertically upward on the side of the occipital protuber- 
 ance. These two branches, which are very tortuous, cover the occipital region with 
 their numerous ramifications, and reach as high as the vertex, anastomosing with each 
 other, and with the superficial temporal arteries. 
 
 It is situated deeply at its origin, and is covered by the digastric muscle and the hypo- 
 glossal nerve ; it is still more deeply situated as it passes between the mastoid process 
 and the atlas, where it is covered by the digastric and the sterno-mastoid ; its horizon- 
 tal portion is situated between the obhquus capitis superior and the splenius muscle, then 
 between the complexus and the splenius, running along the occipital insertion of the lat- 
 ter muscle, on the inner side of which it becomes sub-cutaneous. The two branches 
 into which this artery divides, and all its succeeding ramifications, are situated between 
 the skin on the one hand, and the occipital muscle and the oceipito-frontal aponeurosis 
 on the other. 
 
 Collateral Branches. — Among a great number of small and unnamed ramusculi, we 
 shall distinguish the following branches : a superior sterno-mastoid artery, which constant- 
 ly exists, but is sometimes given off from the external carotid itself: it forms a curve, 
 with its concavity directed downward, under which the hypo-glossal nerve turns ; it then 
 penetrates the deep surface of the upper portion of the stemo-raastoid : a stylo-mastoid 
 branch, which is often derived from the posterior auricular artery : a meningeal artery, or 
 posterior mastoid, which enters the cranium, either by the foramen mastoideum, the fo- 
 ramen lacerum posterius, or even the foramen magnum, and is distributed to the dura 
 mater : & cervical artery {princeps cervicis), which descends between the splenius and com- 
 plexus muscles, and may be followed down to the lower part of the neck ; this branch is 
 sometimes of considerable size ; lastly, very often, a terminal branch, the parietal, which 
 enters the cranium by the parietal foramen, and ramifies in that portion of the dura ma- 
 ter which forms the superior longitudinal sinus. 
 
 The Posterior Auricular Artery^ 
 
 Dissection. — ^Avoid cutting this artery at its origin in preparing the trunk of the exter- 
 nal carotid ; turn the pinna of the ear forward ; seek for the trurdc of the artery between 
 the meatus auditorius extemus and the mastoid process ; follow up the dissection on 
 one side towards the origin, on the other towards the termination of this artery, being 
 guided by the description. 
 
 The posterior auricular artery {,s,fig. 204) is intended for the pinna, the internal ear, and 
 the neighbouring parts of the cranium : it is usually smaller than the occipital, but is 
 sometimes as large ; it arises from the back of the external carotid, a little above the 
 occipital,' and rather often by a common trunk with that artery. It passes vertically up- 
 ward, being deeply seated under the digastricus ; it is then covered by the parotid gland, 
 which it perforates to gain the posterior border of the mastoid process, upon which it di- 
 vides into two branches, a mastoid, and an auricular. 
 
 In this course it gives off several parotid and muscular branches, and the stylo-mastoid 
 artery, which is sometimes derived from the occipital. The stylo-mastoid artery, so re- 
 
520 ANGEIOLOGY. 
 
 markable for the length of its course, dips into the stylo-mastoid foramen, runs the whole 
 length of the aqueduct of Fallopius, giving off, as it proceeds, some twigs to the internal 
 ear, and terminates by anastomosing with a branch of the middle meningeal artery, which 
 enters by the aqueduct of Fallopius. 
 
 The terminal mastoid branch of the posterior auricular passes upward and backward be- 
 tween the mastoid process and the skin, and subdivides into two sub-cutaneous ramus- 
 culi : one horizontal, which passes inward along the occipital attachment of the sterno- 
 mastoid and splenius ; the other ascending, which continues in the original course of 
 the vessel, and is lost in the skin upon the outer margin of the occipitalis muscle. 
 
 The terminal auricular branch almost always divides into two : a superior and an infe- 
 rior. The superior branch runs along the anterior border of the mastoid process, rami- 
 ■ fies upon the upper half of the internal surface of the pinna, and turns round its free mar- 
 gin, so as to reach the external surface. The inferior branch passes behind the auditory 
 meatus, supplies the lobule of the ear, insinuates itself into the fissure in the cartilage, 
 between the helix and concha, and thus gains the external surface of the pinna, upon 
 which it passes upward in the furrow between the helix and antihelix. It terminates by 
 anastomosing with the superior branch. 
 
 I have seen the auricular artery of great size, to supply the place of the posterior 
 branch of the superficial temporal. 
 
 The Parotid Arteries. 
 While passmg through the parotid gland, the external carotid gives ofl^ four or five 
 large branches to that organ, which deserve special description. They arise from the 
 carotid at right angles, cross the ramus of the lower jaw also at right angles, and divide 
 into a great number of ramifications, most of which are lost in the substance of the 
 gland ; the remainder are distributed to the skin and muscles. One or more of these 
 branches pass between the parotid gland and the masseter muscle, parallel to the trans- 
 versalis faciei artery, and reach as far as the zygomaticus major ; others gain the angle 
 of the jaw, and are lost in the supra-hyoid region. 
 
 The Inferior or Ascending Pharyngeal, or Pharyngo-meningeal Artery. 
 
 Dissection. — Make the section necessary for examining the pharynx, as described in 
 d former part of this work when on the Anatomy of the Pharynx. The steps required 
 for this purpose render it advisable that the study of this artery should be postponed until 
 after that of the internal maxillary. 
 
 The ascending pharyngeal is the smallest branch of the external carotid : it arises from 
 the inner side of that artery opposite the lingual. I have seen it arise from the occipital. 
 Not unfrequently it is given off either from the angle of bifurcation of the common caro- 
 tid, or from the internal carotid ; and in this last case, there is almost always a very 
 small pharyngeal branch arising from the external carotid, and passing transversely in- 
 ward to the pharynx. 
 
 It varies in size to a certain degree, and, as it appears to me, in an inverse ratio to 
 that of the palatine branch of the facial. I have seen it almost as large as the occipital. 
 
 Inunediately after its commencement the ascending pharyngeal passes vertically up- 
 ward, at first between the external and internal carotid, and then behind the internal ca- 
 rotid, with which latter vessel it is found in the triangular interval between the pharynx 
 and the internal pterygoid muscle ; it then almost immediately divides into two branch 
 es, a meningeal and a pharyngeal. 
 
 Before dividing, it gives off an inferior pharyngeal branch, which passes transversely 
 inward, and subdivides into ascending and descending branches, the latter of which an- 
 astomose on the pharynx with some twigs of the superior thyroid. 
 
 The meningeal branch, which is situated behind the internal carotid, passes vertically 
 upward, gives off twigs to the superior cervical ganglion of the sjTnpathetic nerve, to the 
 pneumogastric, glosso-pharyngeal, and hypo-glossal nerves, and to the accessory nerve 
 of Willis, enters the cranium through the foramen lacerum posterius, and ramifies upon 
 that portion of the dura mater which lines the inferior occipital fossa. I have seen this 
 vessel divide into a great number of branches, one of which entered the cranium by the 
 carotid canal, and another by the foramen lacerum anterius. 
 
 The meningeal branch, and sometimes even the trunk of the pharyngeal, gives off a 
 prcBvertebral branch, which passes upward in front of the longus colli and the recti antici 
 major et minor, supplying these muscles, and anastomosing with the cervicalis ascen- 
 dens. I have traced a branch into the cranium through the first intervertebral foramen 
 (i. e., along the superior notch of the atlas), and another which entered the vertebral ca- 
 nal between the atlas and axis. I regard this praevertebral branch as supplementary to the 
 cervicalis ascendens (a branch of the inferior thyroid), for it has a similar distribution. 
 
 The pharyngeal branch passes in front of the internal carotid, and having reached the 
 base of the cranium, divides into numerous branches, which ramify in the very dense 
 fibrous tissue found at the occipital attachment of the pharynx : they are all reflected 
 downward, and are distributed upon the Eustachian tube and the muscles of the pharynx. 
 
THE TEMPORAL ARTERY. S^f 
 
 In a case in which the palatine branch of the facial artery was absent, this pharyngea. 
 branch was very large and supplied the tonsil, and, finally, ramified in the velum palati. 
 
 The Temporal Artery. 
 
 Dissectton. — ^Tum bacK the parotid gland ; seek for the artery under the skin of the 
 temporal region ; follow its different collateral and terminal branches upon the cranium 
 as far as the vertex, on the face, and on the ear. 
 
 The temporal or superficial temporal artery (p, fig. 204) appears, by its direction, to form 
 the continuation of the external carotid. It commences opposite the neck of the con- 
 dyle of the lower jaw, between it and the external auditory meatus, which is behind ; it 
 passes vertically upward, immediately behind the zygomatic arch, reaches the temporal 
 region, where it describes some curves, still continuing its vertical course, and termi 
 nates by bifurcating at the middle, or sometimes the upper part of that region. 
 
 Relations. — It is covered at its origin by the parotid gland ; it becomes subcutaneous 
 as soon as it passes beyond the zygomatic arch, and then rests upon the temporal fziscia 
 at first, and upon the epicranial aponeurosis afterward. Its superficisd position, added 
 to its proximity to a bony surface, render it easily compressible, and explain why this 
 artery, and especially its anterior or frontal branch, is generally chosen for arteriotomy. 
 
 Collateral Branches. — These are divided into anterior, posterior, and interned. 
 
 The Anterior Branches. — The most remarkable of these is the transversalis faciei (u), 
 which arises from the temporal immediately after its origin, opposite the neck of the 
 condyle of the lower jaw. and, consequently, in the substance of the parotid gland : it 
 very often comes directly from the external carotid. It varies much in its size, which 
 is generally in an inverse proportion to that of the facial artery. It proceeds horizon 
 tally forward, across the direction of the neck of the condyle and the masseter muscle, 
 about six lines below the zygoma, above the Stenonian duct, which runs parallel to it. 
 Tlie transversalis faciei gives an articular branch to the temporo-maxillary articulation, 
 and several deep masseteric branches, of which one of considerable size penetrates the 
 back part of the muscle, and anastomoses with the masseteric branch of the internal 
 maxillary. It also gives a small twig, which runs along the Stenonian duct. At the 
 anterior margin of the masseter the transverse facial artery subdivides into a great num- 
 ber of cutaneous, muscular, and anastomotic branches. Among the first we should notice 
 a maiar cutaneous branch ; and among the muscular branches, those which are distributed 
 to the great zygomatic muscle. The muscular branches of the transversalis faciei may 
 be traced in one direction as far as the orbicularis palpebrarum, and in another into the 
 levator proprms fibii superioris. The anastomotic branches establish an intimate com- 
 munication between the temporal artery and the buccal, infra-orbital, and facial arteries. 
 
 A second anterior branch of the temporal artery also requires special notice, viz., the 
 orbital, which is given off above the zygomatic arch, passes from behind forward, be- 
 tween the superficial and deep layers of the temporal fascia, then behind the orbicularis 
 muscle, which it supplies, as well as the corresponding skin, and anastomoses with the 
 superior palpebral branch of the ophthalmic. This artery is very variable in regard to 
 size. I have seen it very large and reflected upward, between the frontalis muscle and 
 the skin, parallel to the supra-orbital branch of the ophthalmic, and capable of being fol- 
 lowed as far as the parietal region. From the bend which it forms by turning upward, 
 it gives off a palpebral branch, which completes the superior palpebral arch, and also a 
 branch which anastomoses with the supra-orbital. This orbital branch of the tempered 
 does not exist in all subjects ; the branches which it furnishes are then given off direct- 
 ly from the temporal. 
 
 The posterior branches consist of the anterior auriculars (v), which are irregular as to 
 number : the lower branches are distributed to the lobule, the middle ones to the exter- 
 nal auditory meatus, and the upper branches to the highest part of the pinna. 
 
 The internal branch is the middle deep or sub-aponeurotic temporal artery ; it arises from 
 the temporal above, sometimes on a level with the zygoma, perforates the fascia, and is 
 distributed to the temporal muscle, anastomosing with the anterior and posterior deep 
 temporal branches derived from the internal maxillary. 
 
 Terminal Branches. — Of the two branches into which the temporal artery divides, the 
 anterior or frontal {q) passes forward and upward towards the frontal region, upon which 
 it ramifies, anastomosing with the branches of the frontal and supra-orbital arteries, and 
 with the temporal of the opposite side. This branch is divided in the operation of arte- 
 riotomy. The posterior or parietal branch (y) is larger than the anterior : it passes up- 
 ward and ramifies upon the parietal bone, anastomosing with the auricular and occipital 
 arteries, with the frontal branch of the temporal, and with the temporal of the opposite 
 side. It is 'sometimes derived from the auricular artery. 
 
 The Internal Maxillary Artery. 
 Dissection. — Saw through the zygomatic arch in two places, and turn it downward to- 
 gether with the masseter muscle, taking care not to tear the masseteric artery. 
 Dissect the temporal muscle, and saw through the coronoid process of the inferior 
 
 Uuu 
 
SS2 ANGEIOLOGY. 
 
 maxilla. Saw through the cranium circularly, and remoTc the brain, which may be put 
 into diluted nitric acid or alcohol, to be hardened for the subsequent dissection of the 
 cerebral arteries. The artery may then be exposed in two ways, either from the outer 
 or else from the upper wall of the zygomatic fossa. 
 
 It may be reached from the outer wall of the zygomatic fossa by sawing through the 
 lower jaw in front of the masseter, by disarticulating the condyle, or, rather, by sawing 
 it across its neck, and by carefully dissecting the pterygoid muscles 
 
 The artery can be reached from the upper wall by making two sections in this part of 
 
 the bone, which will meet at an acute angle in the foramen spinosum of the sphenoid bone. 
 
 The branches of this artery, especially those which are e"hclosed in bony canals, such 
 
 as the dental, the pterygo-palatine. the vidian, dec, must be dissected by carving out 
 
 their courses in the bone. 
 
 A vertical section, made from oefore backward through the middle of the face, facili- 
 tates the examination of this artery, and enables us to see the terminations of its nasal, 
 palatine, and pharyngeal branches. 
 
 The internal maxillary artery (e, fig. 206), little known to the older anatomists, but ac- 
 Fig. 206. curately described by Haller, is the continuation of the 
 
 external carotid, at least as far as size is concerned. 
 Immediately after its origin, it forms a curve, and 
 passes deeply to the inner side of the neck of the con- 
 dyle of the lower jaw. 
 
 Tortuous and horizontal in the first part of its course, 
 it traverses the zygomato-maxillary fossa diagonally, 
 passes forward, inward, and a little upward, to reach 
 the highest part of the tuberosity of the superior max- 
 illary bone, upon which tuberosity it describes a very 
 considerable curve with the convexity turned for- 
 ward, and then dips into the bottom of the zygomat- 
 ic fossa, i. e., the spheno-maxillary fossa, where it ter- 
 minates by one or several branches, called the sphe- 
 no-palatine. The tortuous course of the internal max- 
 illary is connected with the great number of branches 
 given off from it. 
 
 Relations. — Opposite the neck of the condyle, it is situated between the condyle, to 
 which it is applied, and the styloid process — an important relation in a surgical point of 
 view. Its relations in the zygomato-maxillary fossa are not very definite. Some anat- 
 omists, with Bichat and Meckel, state that it is situated between the internal and exter- 
 nal pterygoid muscles ; others, with Haller, that it is placed in front of the external pte- 
 rygoid, i. e., between that muscle and the temporal. Both modes of distribution are 
 equally common, and I have even seen one existing on the right, and the other on the 
 left side in the same subject. If the internal maxillary is situated betwt en the ptery- 
 goids, it passes directly forward, on the outside of the dental and lingual nerves ; when 
 it has to get between the external pterygoid and the temporal, it bends downward and 
 then upward, so as to embrace the lower half of the circumference of the external pte- 
 rygoid : in this manner it gains the outer surface of that muscle, appears opposite the 
 sigmoid notch of the lower jaw, and passes from behind forward, between the external 
 pterygoid and temporal muscles ; in both cases it passes between the two origins of the 
 external pterygoid, in order to reach the pterygo-maxillary fissure. 
 
 Collateral Branches. — These are thirteen in number, and are divided into those arising 
 on the inner side, and near the neck of the condyle, viz., the tympanic, the middle menin- 
 geal, and inferior dental, the posterior deep temporal, the masseteric, the pterygoids, and the 
 small meningeal arteries ; those arising near the maxillary tuberosity, viz., the buccal, the 
 anterior deep temporal, the alveolar, and the infra-orhital arteries ; and those arising with- 
 in the spheno-maxillary fossa, viz., the vidian ot pterygoid, the pterygo-palatine, and the 
 guperior palatine arteries. 
 
 Branches arising near the Neck of the Condyle. 
 
 The tympanic artery is a very small branch, which sometimes arises from the tempo- 
 ral, and sometimes from the inferior dental ; it is distributed to the external auditory 
 meatus and the temporo-maxillary articulation, and penetrates through the Glasserian 
 fissure into the cavity of the tympanum, to the muscles and walls of which it sends its 
 ramifications. 
 
 The middle or great meningeal artery, or spheno-spinous artery, is destined for the dura 
 mater and the bones of the cranium ; it almost always arises from the internal maxilla- 
 ry before the dental, but sometimes in the same situation ; it passes vertically upward, 
 behind the neck of the condyle, and gains the foramen spinosum in the sphenoid bone, 
 through which it enters into the interior of the cranium ; it is then reflected upon the 
 anterior margin of this foramen, becomes horizontal, and divides into two branches, an 
 interior and a posterior. The anterior branch is the larger ; it runs upon the outer ex- 
 
THE INTERNAL MAXILLARY ARTERY. "iSfe 
 
 tremity of the lesser wing of the sphenoid, and reaches the anterior angle of tho parietal 
 bone, where it is received into an imperfect, and sometimes even into a complete bony 
 canal, and then divides and subdivides in the ramified grooves upon the internal surface 
 of the parietal bone. Its branches may be traced even into the walls of the longitudinal 
 sinus. 
 
 The posterior branch is smaller, and passes backward and upward upon the squamous 
 portion of the temporal bone, and upon the internal surface of the parietal bone, enters 
 into the ramified grooves upon that surface, and terminates in the dura mater and the 
 bones of the cranium. The ultimate twigs of the middle meningeal artery anastomose 
 with those of the opposite side, and with the branches of the anterior and posterior me- 
 ningeal arteries. 
 
 Relations. — In the first part of its course, it is very deeply situated, and is in relation 
 in front with the condyloid attachments of the external pterygoid muscle ; in the crani- 
 um it is situated on the outer surface of the dura mater, between that membrane and the 
 bones, into the substance of which it sends a number of extremely fine ramusculi. The 
 relation of the two divisions of this artery with the two inferior angles of the parietal 
 bone deserves notice in a surgical point of view. In consequence of its sending branch- 
 es into the bones, separation of the dura mater is always followed by effusion of blood. 
 
 The middle meningeal artery also gives off some collateral branches. On the outside 
 of the cranium it furnishes some unnamed twigs. Within the cranium it gives a small 
 branch, named the vidian, which enters the aqueduct of Fallopius through the hiatus Fal- 
 lopii, and supplies the facial nerve, ramifying in its neurilemma, and anastomosing with 
 the stylo-mastoid branch of the occipital artery ; some small branches, which supply the 
 fifth or trigeminal nerve, and evidently anastomose with the meningeal branches of the 
 internal carotid ; a small twig, which enters the canal for the internal muscle of the 
 malleus, and is distributed upon that muscle ; opposite the sphenoidal fissure, several 
 orbital branches, which enter the orbit at the narrowest part of that fissure, or even by 
 proper canals in its neighbourhood ; and, lastly, some rather large temporal branches, 
 which pass into the great alae of the sphenoid at their orbital surface, and anastomose in 
 the temporal fossa with the deep temporal arteries : not unfrequently the lachrymal ar- 
 tery, or a small supplementary lachrymal artery, is furnished by the middle meningeal. 
 
 The inferior dental artery (d) is the artery of the lower jaw : it generally arises on a 
 level with the middle meningeal, but sometimes before and sometimes after that vessel ; 
 it passes downward, along the inner surface of the ramus of the jaw, between the bone 
 and the internal pterygoid, sending off branches to that muscle, but being separated 
 from it by the fibrous band called the spheno-maxillary ligament ; it thus reaches the 
 superior orifice of the dental canal, before entering which it gives off a small branch 
 that passes downward and forward in a groove on the inner surface of the jaw, and ter- 
 minates in the mylo-hyoid muscle. 
 
 The inferior dental artery traverses the entire length of the dental canal, accompanied 
 by the nerve of the same name. Opposite the bicuspid teeth it divides into two branch- 
 es : a menial branch, the larger, which escapes through the mental foramen, and anasto- 
 moses with the submental artery and the inferior coronary artery of the lip ; and an in- 
 cisor branch, which continues in the original course of the artery, passes beneath the 
 canine and incisor teeth, and is lost in the diploe opposite the symphysis. 
 
 During its course, the dental artery, as well as its incisor branch, gives off a great 
 number of twigs, which are lost in the diploe of the bone ; and a series of dental branches, 
 which correspond in number with the roots of the teeth, penetrate into the alveoli, and 
 from thence into the teeth through the foramen observed at the apex of each fang. 
 
 The posterior deep temporal artery (g) arises opposite the sigmoid notch, passes verti- 
 cally upward between the external pterygoid and the temporal muscles, gains the pos- 
 terior border of the latter muscle, gets between that border and the temporal fossa, re- 
 mains in contact with the periosteum, and then divides and subdivides so as to termi- 
 nate partly in the temporal muscle and partly upon the periosteum, anastomosing with 
 the middle and anterior deep temporal arteries. It often gives off the masseteric, and 
 sometimes the buccal artery. 
 
 The masseteric artery is a small branch, the size of which is inversely proportioned to 
 that of the masseteric branch of the transversalis faciei. It often arises by a common 
 trunk with the posterior deep temporal, passes outward in front of the condyle, and, tliere- 
 fore, in the notch between the condyle and the coronoid process, and enters the internal 
 surface of the masseter, in which muscle it anastomoses with the masseteric branches 
 given off by the transversalis faciei and facial arteries. 
 
 The pterygoid arteries are irregular in number ; some of them arise directly from the 
 internal maxillary, others from the posterior deep temporal and the middle meningeal. 
 
 The small meningeal artery is not constant, but I have seen it in one case as large as ■ 
 the middle meningeal ; it arises at the same height as the inferior dental, passes between 
 the pterygoid muscles, and divides into two branches, one of which turns round the ori- 
 gin of the internal pterygoid, and terminates in the velum palati and the nasal fossae ; 
 and another, which passes vertically upward, between the external pterygoid and the 
 
m 
 
 ANGEIOLOGY. 
 
 upper wall of the zygomatic fossa, enters the cranium by the foramen ovale, and sup- 
 plies the trip^eminal nerve and the dura mater, anastomosing with small branches given 
 off from the internal carotifl. 
 
 Branches arising near the Tuberosity of the Superior Maxillary Bone. 
 
 The buccal artery (h) is a small branch of variable size, and sometimes exists only in 
 a rudimentary state. It rather frequently arises by a common trunk with the superior 
 dental artery, passes in a tortuous course from behind forward, between the ramus of 
 the lower jaw and the internal pterygoid muscle, emerges in front of the ramus, and is 
 lost in the buccinator muscle, anastomosing with the buccal branches of the facial and 
 transversalis faciei. 
 
 The anterior deep temporal artery (i) is of considerable size : it passes vertically up- 
 ward, along the anterior border of the temporal muscle, with which it is in contact, is 
 lost in that muscle, anastomosing with the posterior deep temporal and the middle tem- 
 poral. It gives off some extremely delicate orbital branches, which traverse the canals 
 in the malar bone, and are lost in the adipose tissue of the orbit. 
 
 The alveolar or superior dental (Z) often arises by a common trunk with the infra-or- 
 bital, passes in a very tortuous manner forward and downward upon the tuberosity of 
 the superior maxilla, and divides into several branches ; some of these, having reached 
 the alveolar border, are reflected upon the margins of the alveoli, pass into their cavities, 
 and ramify in the alveolo-dental periosteum ; other branches enter the small posterior 
 dental canals, penetrate into the alveoli of the molars and bicuspids, and divide into as 
 many ramusculi as there are roots to each of those teeth. Several of these branches 
 penetrate into the maxillary sinus. I have seen one which ran along this sinus from 
 behind forward near its lower wall, was reflected upward on the anterior wall of the 
 same cavity, and entered the base of the ascending process of the superior maxilla, at 
 which point I could no longer follow it. This branch was situated between the lining 
 membrane of the sinus and the bones. All the divisions of the alveolar artery furnish 
 branches to the superior maxillary bone, and, at the same time, supply them to the cor- 
 responding teeth. Lastly, some very delicate twigs of the superior dental artery enter 
 the buccinator muscle. 
 
 The infra-orbital artery arises from the internal maxillary opposite the spheno-mEixil- 
 lary fissure, sometimes alone, sometimes by a common trunk with the superior dental, 
 immediately enters and then traverses the infra-orbital canal, emerges at the infra-or- 
 bital foramen, and divides into a great number of branches (m), which are distributed to 
 the skin and mucous membrane of the cheek, anastomosing with the facial artery, the 
 transversalis faciei, and the alveolar and buccal branches just described. Several branch- 
 es enter the alveoli of the canine and incisor teeth at their borders : others penetrate 
 into the nasal fossae at the nostril. 
 
 During its course, the infra-orbital artery furnishes a very remarkable branch, which 
 enters the cavity of the orbits, where it divides into two branches, one of which passes 
 directly forward, and is lost in the lower eyelid, while the other, which is larger, turns 
 inward, and inosculates with the inferior palpebral branch of the ophthalmic artery ; an- 
 other branch of the infra-orbital artery enters the anterior dental canal, to supply the 
 canine and incisor teeth, penetrating into the foramina at the points of their fangs, in 
 the same way as in the other teeth. 
 
 Branches arising in the Pterygo-maxillary Fossa. 
 
 The vidian or pterygoid artery is a very small vessel, which, immediately after its com- 
 mencement, enters the vidian canal, traverses its whole length, and then ramifies in the 
 pharynx and around the Eustachian tube. 
 
 I'he pterygo-palatine artery is as small as the preceding, below and to the inner side 
 of which it is situated : it traverses the pterygo-palatine canal, and terminates in the 
 pharynx and on the Eustachian tube. It sometimes arises from the spheno-palatine artery. 
 
 The superior palatine artery is larger than the preceding branches, and pursues a down- 
 ward course : it arises opposite the pterygo-maxillary fissure, passes vertically down- 
 ward, enters the posterior palatine canal, and, having emerged from its inferior orifice, 
 is reflected from behind forward, advances in a tortuous manner (r, fig. 205) between 
 the hard palate and the mucous membrane, in the groove which runs along the alveolar 
 border, and forms an anastomotic arch in the median line, with the palatine artery of 
 the opposite side. Before entering the posterior palatine canal, it gives off some branch- 
 es, which run through the accessory palatine canals, and ramify upon the velum palati. 
 While upon the hard palate, it sends off branches, which are distributed to the glands 
 of the mucous membrane ; others, which are distributed to the gums, and enter at the 
 margins of the alveoli, and supply the alveolo-dental periosteum ; and, lastly, a small 
 nasal branch {t, fig. 205), which enters the anterior palatine canal, bifurcates above like 
 that canal itself, so as to penetrate into each of the nasal fossae, and anastomoses with 
 the spheno-palatine artery of both sides.* 
 
 * There are, in the interior of the bones of the face, as in all spongy bones, true arterial canals, the study of 
 which is not less important than that of the venous canals found in similar situations. 
 
THE INTERNAL CAROTID. 525 
 
 Terminal Branch of the Internal Maxillary Artery. 
 
 This is named the spheno-palatine ; it is a large vessel, often multiple, and is intended 
 exclusively for the pituitary membrane ; it passes from below upward, in a tortuous man- 
 ner, to penetrate the corresponding nasal fossa, by the spheno-palatine foramen, that is, 
 at the back part of the superior meatus, where it immediately divides into two branches : 
 one internal {s, fig. 205), which passes obliquely downward and forward, covers the sep- 
 tum with a complicated network, and anastomoses in front with the nasal branch of the 
 superior palatine ; the other external, which divides into three ramusculi for the three 
 meatuses, and ramifies in them and upon the turbinated bones. Some of the twigs en- 
 ter the sphenoidal and maxillary sinuses, the posterior and the anterior ethmoidal cella^ 
 the frontal sinus, and the lachrymal canal 
 
 All these arteries form areolae of different sizes in the pituitary membrane, and give t, 
 in successful injections, a reticulated aspect ; they are situated between the periosteum 
 and the pituitary membrane, properly so called. The arteries of the turbinated bones 
 are lodged in the areolar cells on the surface of those bones, and in the arterial canals 
 which are hollowed out of them 
 
 Summary of the Distribution of the IrUernal Maxillary Artery 
 
 The internal maxillary sends branches to the organs of mastication and deglutition, to 
 the nasal fossae, to the bones and fibrous membranes of the cranium, to the face, and to 
 the organ of hearing. Its different branches are distributed in the following manner : 
 
 To the passive instruments of mastication, viz., the jaws and teeth, the inferior dental, 
 the superior dental, and the infra-orbital arteries ; to the active organs concerned in that 
 process, the masseteric, the anterior and posterior deep temporal, and the pterygoid arteries. 
 
 To the organs of deglutition, viz., the hard and soft palate and the pharynx, the supe- 
 rior palatine, the small meningeal, the vidian, and the pterygo-palatine arteries. 
 
 To the nasal fossae, some branches of the infra-orbital, and the whole of the spheno- 
 palatine artery ; the latter vessel, and, consequently, the internal maxillary artery also, 
 are very large in those animals which have a highly-developed olfactory apparatus. 
 
 To the organ of hearing, the tympanic artery, those branches of the middle meningeal 
 which enter the hiatus Fallopii, and also those which enter the canal of the internal 
 muscle of the malleus. 
 
 To the face, viz., to the muscles and integuments, the buccal, the infra-orbital, and the 
 merUal arteries. The region of the eye is the only part not supplied by the internal max- 
 illary. 
 
 To the bones of the cranium, and to the dura mater, the middle and the small meningeal 
 arteries. ^ 
 
 The Internal Carotid. 
 
 Dissection. — The simplest method of exposmg this vessel is to make the section for 
 examining the pharynx. The carotid canal must be opened with a chisel, and the outer 
 wall of the cavernous sinus removed. 
 
 The internal carotid is distributed to the anterior part of the brain, and to the eye and 
 its appendages. 
 
 It is one of the two branches into which the common carotid divides : situated, at its 
 origin, on the outside of the external carotid, it passes sometimes vertically upward, par- 
 allel to, and in contact with, that artery, and sometimes behind it, by crossing it at an 
 acute angle opposite the digastric muscle ; it then leaves ine external carotid to pass 
 deeply into the triangular space between the pharynx and the ramus of the lower jaw, 
 and reaches the base of the cranium, into which it penetrates by the carotid canal. After 
 emerging from this canal, it is situated in the cavernous sinus, upon the sides of the 
 sella turcica, is reflected upward on the inner side of the anterior clinoid process, and 
 terminates by dividing into three branches. 
 
 The size of this artery, which is always exactly proportioned to that of the brain, is, 
 in the adult, equal to that of the external carotid ; in the infant it is much larger (ramus 
 grandior carotidis, Vesal.). In man, cis in the whole series of animjds, the relative size 
 of the internal and external carotids is determined by the relative development of the 
 brain and the face. The internal carotid is remarkable for retaining the Same diameter 
 from its commencement to its termination. 
 
 Its direction is generally straight until it reaches the base of the cranium, but some- 
 times it describes a single curve immediately after its commencement, sometimes sev- 
 eral curves having opposite directions. At the base of the cranium, before entering the 
 carotid canaU it becomes horizontal, and then vertical and ascending. 
 
 In traversing the carotid canal, it follows the angular course of that passage ; in the 
 cavernous sinus, it passes directly forward and upward, like the carotid groove ; at oth- 
 er times it describes two distinct curves ; lastly, on the inside of the anterior clinoid 
 process, it is reflected directly upward and a little backward. The double curvature 
 which it describes in traversing the carotid canal and the cavernous sinus has been weU 
 compared to the Roman letter S. The numerous inflections of the internal carotid form 
 
536 ANGEIOL06Y. 
 
 one of the most decided arguments in favour of the opinion that the use of these wind- 
 ings is to retard the passage of the blood. 
 
 Relations : from its Origin to the Base of the Cranium. — At its origin, the internal carot- 
 id is situated as superficially as the termination of the common carotid, and is crossed 
 by the hypoglossal nerve and the occipital artery ; it soon passes behind the external 
 carotid, and becomes deeper and deeper Protected by its position m the triangular 
 space, which is bounded on the inside by the pharynx, and on the outside by the ramus 
 of the lower jaw, it rests behind upon the vertebral column, from which it is separated 
 by the praevertebral muscles and aponeurosis ; it is in relation in front and to the outer 
 side with the stylo-glossus and stylo-pnaryngeus muscles, which pass between it and 
 the external carotid ; on the inside, with the pharynx ; and on the outside and behind, 
 with the internal jugular vein The ascending pharyngeal artery is, moreover, in rela- 
 tion with it behind, and the great sympathetic nerve on the inside : the pneumogastric, 
 glosso-pharyngeal, and h3rpoglossal nerves are situated behind the internal carotid at 
 their exit from the cranium, but soon get to its outer side, between it and the internal 
 jugular vein. 
 
 The relation of the artery with the external surface of the pharynx explains how this 
 vessel may be wounded from the interior of that cavit)'. Sometimes one of its curves 
 approaches the region of the tonsil ; and this may, perhaps, have been the case when 
 the artery has been wounded by an instrument directed transversely outward and car- 
 ried into the tonsil, either to open an abscess or to excise the gland. 
 
 In the carotid canal, tae artery is in relation with the nervous filaments ascending 
 from the superior cervical ganglioa A very thin fibrous lamina, a prolongation of the 
 dura mater, separates the vessel from the bony walls of the canal. Its proximity to the 
 internal ear while traversing the petrous portion of the temporal bone, is probably the 
 cause of the arterial pulsations which are heard in certain cases. 
 
 In the cavernous sinus, the artery is applied against the inner wall of that cavity, and 
 IS, therefore, placed on the inner side of the nerves which pass through the sinus, and 
 more particularly of the sixth pair ; it is said that the artery is not bathed in the blood 
 contained in the sinus, but is protected from it by a very thin layer of membrane, con- 
 tinuous with the internal coat of the veins. However careful I may have been, I have 
 never succeeded in separating this membrane. 
 
 On the inner side of the anterior clinoid process, the artery is upon the outer side of 
 the optic nerve ; and at the point where it emerges from the dura mater, above the an- 
 terior clinoid process, it is received in a sheath formed by the arachnoid. 
 
 Branches of the Internal Carotid. — On the outside of the cranium it gives offno branch, 
 excepting in a few cases where it furnishes the ascending pharyngeal, or, rather, only 
 a supplementary pharyngeal brancl? ; and, lastly, when it gives off the occipital. In the 
 carotid canal, it sends a twig into the cavity of the tympanum by a special opening. In 
 the cavernous sinus, it furnishes several small branches {arterice reccptaculi), some of 
 which are reticulated, and distributed to that portion of the dura mater which lines the 
 basilar surface of the occipital bone, and to the walls of the inferior petrosal sinus ; 
 while others ramify upon the pituitary body, the fifth pair of nerves, and the adjacent 
 portion of the dura mater : a larger branch anastomoses with the middle meningeal ar- 
 tery. 
 
 Lastly, on the inner side of the anterior clinoid process, just as it passes above that 
 process, the internal carotid gives off in front a remarkable artery, named the ophthalmic. 
 
 The Ophthalmic Artery. 
 
 Dissection. — Make a partial injection, either from the common or internal carotid. 
 Remove the roof of the orbit, after having carefully detached the integuments and peri- 
 osteum of the frontal region ; leave a small bridge of bone on the inner part of the 
 margin of the orbit for the supra-orbital artery, or, rather, open the supra-orbital fora- 
 men and disengage the artery from it. Dissect the muscles of the eye with great care, 
 preserving all the vessels which present themselves. The study of the branches of the 
 ophthalmic artery, which are distributed to the ball of the eye, requires a perfect knowl- 
 edge of that organ. 
 
 This artery is principally destined for the eye and its appendages, and is less remark- 
 able for its size, which is inconsiderable, than for the number of its branches. Imme- 
 diately after its origin, it enters the optic foramen {b, fig. 207), on the outer side of and 
 below the optic nerve.* The artery is at first contained in the same sheath as the 
 nerve, but, soon escaping from it, penetrates into the orbit between the abducens oculi 
 nerve and the external rectus muscle of the eye, turns inward and crosses the optic 
 
 ' A very remarkable variety in the origin of the ophthalmic artery is that m which this artery arises by a 
 common trunk with the middle meningeal or arteria media dura matris, which is a branch of the intenial 
 maxillary. In a case of this kind, which has been communicated to me by M. Dubreuil, the ophthalmic ar- 
 tery arose from the anterior branch of the meningeal ; when this branch reached the canal at the anterior in 
 ferior angle of the parietal bone, it entered the orbit by the external extremity of the foramen lacerum or- 
 bitale, and successively gave off the branches furnished by the ophthalmic artery. 
 
THE OPHTHALMIC ARTERY. 527 
 
 nerre, sometimes at right angles and sometimes obliquely, and is then placed above the 
 nerve. Having reached the inner wall of the orbit, it again changes p.. ^^^ 
 
 its direction, passes horizontally and in a slightly tortuous manner ^' 
 
 along the lower border of the superior oblique muscle of the eye, 
 and terminates by bifurcating at the margin of the orbit. Not un- 
 frequently, the ophthalmic artery, immediately after its origin, is 
 placed on the inner side of and below the optic nerve, and then pass- 
 es directly forward along the inner side of that nerve ; so that, in 
 these cases, the nerve and artery do not cross each other. 
 
 The ophthalmic artery gives off a great number of branches, 
 which, according to their origin,* may be divided into those ari- 
 sing on the outside of the optic nerve, viz., the lachrymal artery 
 and the central artery of the retina ; those arising above the nerve, 
 viz., the supra-orbital, the short ciliary, the middle or anterior ciliary, 
 the superior and the inferior muscular arteries ; those arising on the ^5^ ' 
 inner side of the optic nerve, viz., the posterior and anterior eth- 
 moidal and the inferior and superior palpebral arteries ; in all, eleven branches, to which may 
 be added the terminal branches, viz., the nasal and the frontal arteries. It is well to remark, 
 that the origins of most of the above-named branches are subject to extreme variety. 
 
 Branches arising on the Outer Side of the Optic Nerve. — The lachrymal artery {c,Jig. 
 207), one of the largest branches of the ophthahnic, arises immediately before the en- 
 trance of the latter into the orbit. Not unfrequently it is given off from the middle me- 
 ningeal artery. 
 
 The lachrymal artery passes from behind forward along the outer wall of the orbit, 
 between the periosteum and the external rectus muscle, and enters the lachrjTnal gland 
 (/), supplying it with a great number of branches. Emerging from the gland very much 
 reduced in size, it terminates partly in the conjunctiva, and partly in the structures com- 
 posing the upper eyelid. 
 
 In its course it sometimes gives off a small meningeal branch, which passes back- 
 ward through the sphenoidal fissure, and enters the dura mater, in which it anastomoses 
 with the middle meningeal artery. This branch may be considered, in some subjects, 
 as one origin of the lachrymal artery ; a condition that leads to those cases in which 
 the lachrymal artery arises from the middle meningeal. It often gives off a long cihary 
 artery, and always some twigs to the neurilemma of the optic nerve, and muscular 
 branches to the levator palpebrse superioris and the superior rectus ; lastly, it furnishes 
 a muscular branch, the malar, which perforates the malar bone, and anastomoses in the 
 temporal fossa with the anterior deep temporal artery, and upon the malar bone itself 
 with the transversalis faciei. 
 
 The central artery of the retina {artena centralis renna, t), quite distinct from the twigs 
 supplied to the neurilemma of the optic nerve, is an extremely delicate vessel : it arises 
 either from the ophthalmic, or from one of the ciliary arteries, penetrates obliquely into 
 the substance of the nerve, runs along its centre from behind forward, enters into the 
 globe of the eye, and expands in diverging ramifications, which are applied to the inter- 
 nal surface of the retina, and accompany it as far as the ciliary processes. A branch 
 very distinct from those just mentioned traverses the vitreous body from behind forward, 
 in the axis of the eye, and reaches the capsule of the crystalline lens, after having fur 
 nished some extremely fine twigs to the hyaloid membrane. 
 
 Branches arising above the Optic Nerve. — The supra-orbital or superciliary artery (d) 
 arises from the ophthalmic as that vessel is crossing the optic nerve ; it is sometimes 
 given off from the lachrymal. It is very variable in size, and appears in certain cases 
 to be partially replaced by the orbital branch of the temporal, or by the frontal branch 
 of the ophthalmic. It passes horizontally between the periosteum of the roof of the or- 
 bit and the levator palpebrae superioris, accompanied by the frontal nerve ; it escapes 
 from the orbit at the superciliary notch, is reflected over it as over a pulley, ascends 
 vertically, and divides into two branches, one of which passes upward between the skin 
 and the orbicularis and occipito-frontalis muscles, and the other is situated between the 
 muscles and the periosteum, and ramifies in that membrane. The sub-cutaneous branch 
 often divides into an internal and an external twig. It is also said constantly to furnish 
 a branch to the diploe of the frontal bone, as it is passing through the superciliary notch. 
 It appears to me that this branch is often wanting. 
 
 The ciliary arteries may be divided into the posterior or short, the mjiddle or long, and 
 the anterior. 
 
 The posterior cuiary arteries (r) distributed to the choroid coat and the ciliary processes 
 (arteres uveales, Chauss.) are irregular in number which is stated to be thirty, or even 
 
 * The branches given off by the ophthalmic artery might be more philosophically divided as follows : Ist. 
 Those -which are destined to the globe of the eye, viz., the arteries of the retina, the short cihary or choroi- 
 dian, the middle or long ciliary, and the anterior ciliary ; 2d. Those which are distributed to the parts con- 
 tained in the orbital cavity, lachrymal and muscular arteries ; 3d. Those which are on the outside of tha 
 orbital cavity, the palpebral, sub-orbital, ethmoidal, frontal, and nasal artenes. 
 
628 ANGEIOLOGY. 
 
 forty; they arise from two trunks : one inferior, which is given off from the ophthalmic 
 artery on the outer side of the optic nerve ; the other is superior, and arises above that 
 nerve. Not unfrequently the lachrymal artery gives off the inferior long ciliary trunk. 
 They run in a very tortuous course along the optic nerve, and, having reached the ball 
 of the eye, twist spirally and immediately expand into a tuft of tortuous ramusculi, 
 which surround the optic nerve, perforate the sclerotic coat around the entrance of the 
 nerve, and then ramify, as will be elsewhere stated, in the choroid coat and ciliary pro- 
 cesses. 
 
 The middle or long ciliary arteries (arteres iriennes, Chauss.), which are distributed to 
 the iris, are two in number, an internal and an external ; they perforate the sclerotic at 
 some distance from the optic nerve, and pass between the sclerotic and the choroid 
 membrane on the sides of the eyeball. Having reached the ciliary ring, each of them 
 divides into two branches, which anastomose together, and form the great vascular circle 
 of the iris. Numerous radiating branches proceed from all points of the inner border of 
 this circle towards the free margin of the iris, where they subdivide and anastomose to 
 form the lesser vascular circle of that membrane. 
 
 The anterior ciliary arteries are irregular in number, and are derived from the muscu- 
 lar branches, and sometimes from the lachrymal and infra-orbital ; they give some 
 branches to the conjunctiva, penetrate the sclerotic at a short distance from the cornea, 
 and terminate in the great circle of the iris. 
 
 The muscular arteries are two, viz., the superior and the inferior. The superior is the 
 smaller : it is often wanting, and is then replaced by branches from the lachrymal, infra- 
 orbital, or ciliary arteries. It is distributed to the levator palpebrae superioris, the supe- 
 rior rectus, and the obliquus superior. The inferior, which always exists, passes from 
 behind forward between the optic nerve and the inferior rectus, gives off most of the 
 anterior ciliary arteries, and is distributed to the external and inferior recti, and to the 
 obliquus inferior. Sometimes the inferior muscular is not entirely distributed to the mus- 
 cles, but forms an anastomotic arch with the infra-orbital branch of the internal maxillary. 
 
 Branches arising on the inner Side of the Optic Nerve. — The ethmoidal arteries are two, 
 viz., the anterior and the posterior. The posterior ethmoidal (e) is given off the first 
 from the ophthalmic, and is sometimes as large as the continuation of that artery : at oth- 
 er times merely a trace of it exists. It runs from without inward, passes through the 
 posterior internal orbital canal to reach the ethmoidal groove within the cranium, and 
 then divides into a meningeal and a nasal branch. The meningeal ramifies in the dura 
 mater, particularly in the falx cerebri ; the nasal branch enters the nasal fossa, through 
 the foramina of the cribriform plate, and anastomoses with the ultimate divisions of the 
 spheno-palatine artery. 
 
 The anterior ethmoidal (/) is mversely proportioned, as regards size, lo the posterior 
 artery, which is sometimes replaced by it ; it enters the cranium through the anterior 
 internal orbital canal, and divides into a meningeal branch, distributed upon the fabc cer- 
 ebri, and a nasal branch, which penetrates the olfactory cavities by the foramina of the 
 cribiform plate. The branches to the falx are remarkably tortuous. 
 
 The palpebral arteries are divided into the superior and the inferior. Both arise from 
 the ophthalmic, opposite the cartilaginous pulley of the superior oblique. Sometimes 
 they arise by a common trunk. Most commonly the inferior palpebral is given off a lit- 
 tle before the superior. Sometimes the superior is so large that it appears to result 
 from a division of the ophthalmic itself into two equal branches. 
 
 The inferior palpebral passes vertically downward, behind the tendon of the orbicularis 
 muscle, proceeds outward to reach the lower eyelid, along the whole length of which it 
 runs in the form of an arch without any winding, and is gradually lost at the external 
 canthus or angle of the eyelids. 
 
 The vascular arch thus formed, the inferior palpebral, is situated between the muscular 
 fibres of the eyehd and the tarsal cartilage, immediately below the free border of that 
 cartilage. 
 
 At the point where it enters the eyelid, it gives off a very remarkahle branch, which 
 anastomoses with the orbital branch of the infra-orbital artery. From the arch of anas- 
 tomosis a branch arises, which enters the nasal duct (branch of the nasal duct), and ram- 
 ifies in the mucous membrane of that passage, as far as the inferior meatus. 
 
 The superior palpebral passes downward behind the orbicularis palpebrarum, and, having 
 reached the superior punctum lachrymale, is reflected outward, between the muscular 
 fibres and the tarsal cartilage, immediately above its free border, along which it forms 
 an arch, and terminates by anastomosing with a palpebral branch derived from the su- 
 perficial temporal. 
 
 Terminal Branches of the Ophthalmic. — At the anterior extremity of the angle formed 
 by the upper and internal walls of the orbit, the ophthalmic artery terminates by divi- 
 ding into a nasal and a frontal branch. 
 
 The 7iasal branch varies in size, and is often larger than the ophthalmic artery itself, 
 so that some anatomists have regarded it as a branch of the facial, with which it always 
 anastomoses. It emerges from the orbit above the tendon of the orbicularis, and hav' 
 
UEttEBRAL BRANCHES OF THE INTERNAL CAROTID. 
 
 
 (ng given off a small branch, which afterward enters the groove in the os unguis, to be 
 distributed to the mucous membrane of the lachrymal sac, it divides into two branches : 
 one, named the angular artery, runs in the groove formed by the nose and cheek, be- 
 tween the pyramidalis nasi and the levator labii superioris alaeque nasi ; it is accompa- 
 nied by the vein, which lies to its outer side, and it is continuous with the facial artery, 
 without any line of demarcation, the two vessels inosculating so completely, that it is 
 impossible to define their respective limits : the other branch, the dorsal artery of the 
 nose, runs along the dorsum of the nose, and terminates opposite each ala by anastomo- 
 sing with its corresponding artery. These two divisions of the nasal branch of the oph- 
 thalmic are sub-cutaneous, and give off numerous ramifications, which cover the whole 
 surface of the nose. 
 
 The frontal branch is smaller than the nasal, and generally smaller than the supra- 
 orbital or superciliary ; it passes upward upon the forehead, parallel to the supra-orbital, 
 with which it communicates above by a transverse branch ; it divides into sub-cutaneous 
 twigs, situated between the skin and the muscles, and into muscular and periosteal t\yigs. 
 
 Summary of the Distribution of the Ophthalmic Artery, — The ophthalmic sends branches 
 to the ball of the eye, to its appendages, viz., the muscles, eyelids, and lachrymal appa- 
 ratus, to the frontal region, and to the nose and nasal fossae. 
 
 To the ball of the eye it gives the arteria centralis retinae, which supplies the retina, 
 the hyaloid membrane, and the capsule of the crystalline lens ; the posterior, middle, 
 and anterior ciliary arteries, which are distributed to the choroid membrane, the ciliary 
 processes, and the iris. 
 
 It supplies proper muscular branches, and also twigs from its other branches, to the 
 muscles of the eye. 
 
 To the eyelids it gives off the palpebral arteries. To the lachrymal apparatus it sup- 
 plies the lachrymal artery for the gland, and the two branches for the lachrymal sac and 
 the nasal duct. 
 
 The frontal region receives its frontal and supra-orbital branches ; the nose, the nasal 
 branch, and the nasal fossae, the anterior and posterior ethmoidal arteries. 
 
 The Cerebral Branches of the Internal Carotid Artery. 
 When the internal carotid has given off the ophthalmic artery, it enters (c, fig, 208> a 
 
 Fig. 208. 
 
 deep fossa seen on the base of the brain at the inner 
 end of the fissure of Sylvius, and immediately divides 
 into three branches, which spread out from each other. 
 
 Of these three branches, the anterior is called the 
 anterior cerebral, or artery of the corpus callosum ; the 
 external is named the middle cerebral, or artery of the 
 fissure of Sylvius ; and the third, or posterior, is the 
 posterior communicating artery. 
 
 Not unfrequently the carotid gives origin to the pos- 
 terior cerebral artery, from which, in that case, the 
 posterior communicating artery is then given off, and 
 immediately joins the anterior extremity of the basi- |^/ 
 lar artery. 
 
 The Anterior Cerebral Artery. Dissection. — The 
 study of these arteries requires no preparation ; it is 
 sufficient to overturn the brain in a manner which 
 will bring its base into view. Each artery will be 
 recognised by the following description : This vessel 
 {d d, fig. 208), also called the artery of the corpus cal- 
 losum, passes, immediately after its origin, forward 
 and inward, towards the median line, and thus reaches the longitudinal fissure between 
 the right and left anterior lobes of the brain. There it approaches its fellow of the op- 
 posite side, and communicates with it by a transverse branch, which passes at right an- 
 gles between them. This anastomotic branch (a), so remarkable for its size, shortness. 
 and direction, is called the anterior communicating artery ; instead of one, there are some- 
 times two smaller branches ; sometimes it is so short that the two anterior cerebral ar- 
 teries may be said to be applied to each other, and blended together at this point : most 
 commonly it is from one to two lines in length, and it then gives off some small twigs. 
 which penetrate into the third ventricle. 
 
 ^Lfter communicating in this manner, the anterior cerebral arteries become parallel, 
 run from behind forward, turn upward in front of the anterior extremity of the corpus 
 callosum, and then run backward upon its upper surface, as far as its posterior extremity, 
 describing a curve, which exactly corresponds with that of the corpus callosum itself 
 
 Before turning over the anterior border of the corpus callosum, the anterior cere 
 bral arteries give off some ramuscuh to the optic and olfactory nerves, to the third ven- 
 tricle, and the adjacent part of the anterior lobe of the brain,"and also a series of large 
 branches, which are distributed to the inferior surface of the samr lobe. At the poin* 
 
 X X X 
 
530 ANGEIOLOGY. 
 
 where the arteries are reflected, and also along the upper surface of the corpus callosum, 
 large branches arise from the convexity of the curve described by these vessels, and 
 ramify upon the inner surface of the two hemispheres : the anterior branches run from 
 behind forward, and the others from before backward, and from below upward ; most of 
 them reach the convex surface of the brain. Some capillary twigs proceed from the con- 
 cavity of the curve, and penetrate the substance of the corpus callosum. 
 
 We may regard as the termination of each anterior cerebral artery a very small branch 
 which continues in the same course, reaches the posterior extremity of the corpus callo- 
 sum, is there reflected downward, and terminates in the adjacent convolutions of the 
 brain. 
 
 The Middle Cerebral Artery. — This is larger than the preceding vessel ; it passes (/, 
 Jig. 208) outward and backward to enter the hssure of Sylvius, having previously given 
 off a great number of rather large branches, which run perpendicularly upward into the 
 very thin layer of cerebral substance situated at the junction of the longitudinal fissure 
 of the brain with the fissure of Sylvius.* 
 
 As soon as the middle cerebral artery has entered the fissure of Sylvius, it divides into 
 three branches : an anterior, which is applied to the anterior lobe ; a posterior, which 
 lies upon the middle lobe ; and a median branch, which corresponds to the small lobe 
 that is concealed within the fissure : they all follow the direction of this fissure, and are 
 concealed within it, but soon emerge so as to ramify upon the convolutions and anfrac- 
 tuosities of the brain, anastomosing with each other, and with the branches of the ante- 
 rior and posterior cerebral arteries. 
 
 It is of importance to remark, and this observation applies to all the cerebral arteries, 
 that the arterial ramifications destined for the surface of the brain are extremely tortuous, 
 that they dip into the anfractuosities, and cover the free borders and the two surfaces of 
 the convolutions, between which they are situated ; that they ramify very freely, and run 
 a very extensive course ; and that they do not divide gradually into smaller and smaller 
 branches, but that bundles of very fine capillary vessels arise from every part of the cir- 
 cumference of vessels of a certain size, and immediately penetrate the cerebral substance. 
 
 The Posterior Communicating Artery, or Communicating Artery of Willis. — This artery 
 varies exceedingly in size, being generally small, but sometimes forming the largest di- 
 vision of the internal carotid. It arises from the back of the carotid, runs from before 
 backward (?), and terminates in the posterior cerebral branch of the basilar artery. In 
 certain cases, the communicating artery of Willis may be regarded as the chief origin 
 of the posterior cerebral, which then seems to result from the union of this communica- 
 ting artery with the anterior bifurcation of the basilar. 
 
 The Choroid Artery. — A very small but constant branch (s) arises from the back of the 
 internal carotid, on the outer side of the communicating artery of Willis. This is the 
 artery of the choroid plexus, which passes backward and outward, along the optic tract, 
 and, consequently, along the eras cerebri, to both of which it sends branches, and then en- 
 ters the lateral ventricle at the anterior extremity of the great transverse fissure of the 
 brain, gives twigs to the hippocampus major and corpus fimbriatum, and terminates in 
 the choroid plexus, t 
 
 Summary of the Distribution of the Common Carotid Arteries. 
 
 The common carotids are distributed to the head, and to the organs which occupy the 
 front of the neck. 
 
 The internal carotid belongs exclusively to the brain, and to the organs of vision ; and 
 hence, doubtless, at least in part, arises that intimate relation between the condition of 
 the brain and of the eye, which is expressed by the common saying, that the eye is the 
 mirror of the soul. 
 
 Although the size of the internal carotid is almost always in proportion to that of the 
 brain, yet this artery is not the only one by which that organ is supplied with blood. The 
 vertebral artery, a large branch of the subclavian, completes the arterial system of the 
 brain ; and the fact of an artery, principally destined for the upper extremity, also send- 
 ing a branch to the brain, proves that there is nothing peculiar in the quality of the blood 
 transmitted to the encephalon. 
 
 We have already seen that the ophthalmic artery communicates by its nasal branch 
 with the facial artery, and by its inferior palpebral branch with the infra-orbital branch 
 of the internal maxilleury. But the internal carotid has no direct communication with the 
 external, unless when it gives origin to the ascending pharyngeal and the occipital arter- 
 ies. I may remark, however, that some meningeal branches are given off by the inter- 
 nal carotid within the cavernous sinus. 
 
 The external carotid differs from the internal, in giving origin to a very great number 
 of branches, which are distributed to the face, to the parietes of the cranium, to the or- 
 gans of respiration, and, lastly, to the organs of digestion. 
 
 The facial branches may be divided into the superficial and the deep-seated. 
 
 * We shall see hereafter that this region of the brain belongs to the corpus striatum. 
 .- ^ f See vertebral artery (p. 533), for the completion of the arterial system of the enceohalon. 
 
ARTERY OF THE UPPER EXTREEITY. 531 
 
 The superficial arteries of the face are derived from many sources. The principal one 
 is furnished by the facial or external maxillary ; the others are the transverse artery, or 
 transverse arteries of the face, coming from the temporal ; the nasal, a descending branch 
 of the ophthalmic ; the buccal, masseteric, infra-orbital, and mental— all derived from 
 the internal maxillary. The arteries of the right side communicate very freely and fully 
 with those of the left ; and on each side, branches from the different sources communi 
 cate as freely with each other ; so that, in hemorrhage from any of them, the injured 
 vessel must be tied on both sides of the wound. I may call attention to the abundance 
 of arterial vessels in the face, and to the number and size of the muscular and cutaneous 
 branches ; this is evidently connected with the extreme susceptibility of the skin of tliis 
 region, the existence of the hair-bulbs, and the action of the muscles in giving expression 
 to the features. 
 
 The deep arteries of the face are principally derived from the internal maxillary. Thus, 
 the spheno-palatine supplies the nasal fossae : some branches of the infra-orbital enter 
 the orbit. We shall afterward allude to the branches which are furnished to the buccal 
 cavity and the zygomatic and spheno-maxillary fossae. Lastly, the superficial and deep 
 arteries of the face are united by numerous anastomoses. 
 
 The first set of cranial branches, derived from the external carotid, are the arteries of 
 the hairy scalp, viz., the occipital, temporal, posterior auricular, supra-orbital, and frontal. 
 With regard to these arteries, it is important to notice their large size, which is connect- 
 ed with the great vitality of the skin of the head, and with the existence of the bulbs of 
 the hair ; also, that they are extremely tortuous, which appears to me to be in corre- 
 spondence with the great number of branches which they give off; and, lastly, that they 
 are situated in the dense cellular tissue which connects the skin with the muscles and 
 the epicranial aponeurosis. 
 
 Besides these, small branches are found upon the pericranium, under the muscles and 
 epicranial aponeurosis : they are seen on the forehead, where they arise from the fron- 
 tal and infra-orbital arteries, and also in the temporal region, where they axe C2illed the 
 deep temporals ; these branches are both periosteal and muscidar. 
 
 The second set of branches to the cranial parietes are arteries of the interior of the cra- 
 nium, viz., the meningeal, the chief of which is the middle meningeal, a branch of the in- 
 ternal maxillary : the others, or small meningeals, enter through most of the foramina 
 at the base of the cranium. Among these latter we would mention the meningeal 
 branches of the ascending pharyngeal artery, and meningeal branches from the ethmoidal 
 arteries, to which may be added some small twigs given off from the internal carotid, 
 while enclosed in the cavernous sinus. 
 
 We may also refer the arteries of the organ of hearing to those of the cranial pirietes. 
 They are the posterior auricular and the anterior auricular, which are distributed to the 
 pinna and to the external meatus ; the tympanic, which passes through the fissure of 
 Glasserus, and a small branch of the middle meningeal, which enters through the hiatus 
 Fallopii. 
 
 The branches of the external carotid distributed to the orguns of digestion belong to the 
 following parts : 
 
 To the organs of mastication, viz., the alveolar, the infra-orbital, and the inferior den- 
 tal arteries, which go to the teeth and the jaws ; the superior palatine, which supplies 
 the roof of the palate ; and, lastly, the deep temporal, the masseteric, and the pterygoid, 
 which are distributed to the muscles of mastication. To the salivary organs : thus, the 
 parotid receives its branches from the external carotid and the temporal ; the sub-max- 
 illary gland from the facial ; and the sub-lingual gland from the sub-lingual branch of the 
 lingual artery. To the velum pdati and the tonsils we find the ascending or inferior 
 palatine branch of the facial artery, the superior palatine branch of the internal maxillary, 
 and the ascending pharyngeal. To the pharynx, the pharyngeal twigs from the superior 
 thyroid, the ascending pharyngeal, the pterygo-palatine or superior pharyngeal, and the 
 vidian from the internal maxillary, and the inferior palatine branch of the facial. To 
 the oesophagus there are the descending oesophageal branches of the superior thjToid. 
 
 The branches given by the external carotid to the air-passages are the superior and infe- 
 rior laryngeal, from the superior thyroid artery, which is essentially distributed to the 
 thyroid gland. 
 
 Aeteet of the Uppee Extremity. 
 
 A aiagle arterial trunk, called the brachial trunk ( Chaussier), is destmed for the upper 
 extremity. On the left side it arises directly from the arch of the aorta, and on the 
 right side from the innominate artery ; it emerges from the thorax, between the first rib 
 and the clavicle, traverses the axilla, runs along the inner side of the arm, passes in front 
 of the elbow-joint, and divides into two branches, which supply the forearm and the hand. 
 
 As the brachial trunk has some highly important relations during its course, and, 
 moreover, furnishes a very great number of branches, it has been artificially divided, in 
 order to facilitate its study : each of the divisions has received a particular name, ac- 
 cording to the region through which it passes : thus, the arterv of the upper extremity 
 
532 ANGEIOLOGY. 
 
 is called successively the sub-clavian, the axillary, and the hwneral artery , and its termi- 
 nal divisions are named the radial and ulnar arteries. 
 
 The Brachio-cephalic Artery. 
 
 The brachio-cephalic or innominate artery {arteria anonyma of many authors, e,fig. 198) 
 is the common trunk of the right sub-clavian and right common carotid arteries, and has 
 in turns been regarded as a portion of the carotid, and as a part of the sub-clavian. It 
 arises from the aorta, at the point where that vessel changes its direction from vertical 
 to horizontal. It is situated in front and to the right of the other arteries given off from 
 the arch of the aorta. It is from one inch to fifteen lines in length. It is directed ob- 
 liquely upward and outward. 
 
 Relations- — In front of the mnommate artery is the sternum, beyond the upper end of 
 which the artery almost always projects, and from which it is separated by the left 
 brachio-cephalic vein, by the remains of the thymus, and by the sternal attachments of 
 the stemo-hyoid and sterno-thyroid muscles. Behind, it is in relation with the trachea, 
 which it crosses obliquely ; on the outer side, with the pleura and mediastinum, which 
 separate it from the lungs ; on its inner side is the left common carotid, from which it is 
 separated by a triangular interval, in which the trachea is seen. 
 
 From a knowledge of these relations, modem surgeons have succeeded in applying a 
 ligature to the innominate artery. Its relations, however, vary in different individuals. 
 In some cases almost the whole length of the vessel projects beyond the sternum ; and 
 it is then extremely accessible, either to accidental wounds, or to the surgeon in the ap 
 plication of a ligature. It has been thought that the presence of the innominate artery 
 explains the predominance of the right over the left upper extremity ; but this opinion 
 is entirely unfounded. 
 
 The arteria innominata gives off no collateral branch, except in those cases in which 
 it affords origin to the thyroid artery of Neubauer, so named from the anatomist who 
 called attention to this anatomical variety.* The same anatomist has seen the right in- 
 ternal mammary artery arise from the brachio-cephahc trunk 
 
 The Right and Left Sub-clavian Arteries. 
 
 The right sub-clavian artery {g, fig. 198 ; f,fig. 204) arises from the innominate (c) ; 
 the left sub-clavian {g"), from the arch of the aorta. 
 
 Varieties of Origin. — One very common variety is that in which the right sub-clavian 
 arises below the left, from the posterior and inferior part of the arch of the aorta, from 
 which it passes upward and to the right side, generally behind the trachea and oesopha- 
 gus, sometimes between the two, and rarely in front of the trachea, t 
 
 The precise termination of this artery is not well defined. By some authors it is said 
 to end, and the vessel to take the name of axillary artery as it passes between the sca- 
 leni.t It appears to me more convenient to take the clavicle as indicating the respect- 
 ive limits of the two vessels. All above the clavicle, then, belongs to the sub-clavian, 
 and all below it to the axillary artery.^ 
 
 From the difference, as to origin, between the right and left sub-clavians, they diffei 
 from each other remarkably in length, direction, and relations. 
 
 Differences in Length. — The right sub-clavian is shorter than the left by the length of 
 the innominate artery ; and we should, moreover, bear in mind the slight difference in 
 the height between the origin of the innominate and the left sub-clavian. The difference 
 in the size of the two sub-clavian arteries requires no special notice. 
 
 Differences in Direction. — The right sub-clavian passes at first obliquely outward and a 
 little upward, and then bends over the apex of the lung, describing a curve with the con- 
 cavity looking downward. The left sub-clavian passes vertically upward before curving 
 over the apex of the lung, opposite which it changes its direction abruptly, and becomes 
 horizontal. 
 
 Differences in Relations. — In describing these, we shall divide the sub-clavian artery 
 into three portions : the^rs^, extending from the origin of the artery to the scaleni mus- 
 cles ; the second, situated between the scaleni ; and the third, extending from the scale- 
 ni to the clavicle. The relations of the right and left sub-clavians differ from each other 
 only in the first of these portions. 
 
 The first portion {I, fig- 204) of the right sub-clavian is in relation in front with the inner 
 end of the clavicle, the sterno-clavicular articulation, the platysma, and the clavicular 
 attachment of the sterno-mastoid muscle, with the stemo-hyoid and sterno-thyroid mus- 
 cles, with the termination of the internal jugular and vertebral veins in the sub-clavian 
 
 * This inferior thyroidean artery arises, perhaps, more frequently from the arch of the aorta, between the 
 brachio-cephalic trunk and the left primitive carotid. 
 
 t [It rarely passes between the trachea and o;sophagTis ; and it appears there is no record of its having been 
 actually seen in front of the trachea (see Quain on the Arteries).'^ 
 
 X According to some authoi-s, the artery changes its name as it emerges from between the scaleni ; accord- 
 ing to others, while it is yet between those muscles. 
 
 ^ We are in the habit of dividing this artery into three portions : a cardiac, a middle, and an axillary por- 
 lion. The first, that part between its origin and the scaleni ; the second, the portion embraced between tho 
 Bcaloni ; and the third, the remaining part of the artery. — Ed. 
 
THE VERTEBRAL ARTERY. 533 
 
 Tein, and with the right pneumogastric and phrenic nerves ; behind, with the recurrent 
 laryngeal nerve and the transverse process of the seventh cervical vertebra ; on the out- 
 er side, with the mediastinal pleura, which separates it from the lung. On the inner 
 side, it is separated from the conmion carotid by a triangular interval.* It is surround- 
 ed by loose cellular tissue, a great number of lymphatic glands, and nervous loops formed 
 by the great sympathetic. 
 
 The first portion of the left sub-clavian is in relation with the same parts, though to a 
 somewhat different extent : thus, its relations with the left mediastinal pleura and lung 
 are much more extensive. The sub-clavian vein crosses it at right angles, instead of 
 being parallel to it ; but the left pneumogastric and phrenic nerves run parallel to, in- 
 stead of crossing it. It is parallel to the left common carotid, instead of forming an an- 
 gle with it ; and, instead of being near the clavicle, the left sub-clavian is close to the 
 vertebral column, and rests on the longus colli, the inferior cervical ganglion of the sym- 
 pathetic nerve, and the thoracic duct, which is there to its inner side. 
 
 The second portion of both the right and left sub-clavian arteries, situated between the 
 scaleni, is in close relation below with the middle of the upper surface of the first rib, on 
 which there is a corresponding depression behind the tubercle for the attachment of the 
 anterior scalenus ; above, with the two scaleni, which are in contact with each other 
 above the vessel ; behind, with the brachial plexus ; in front, with the scalenus anticus, 
 which separates the subclavian artery from the sub-clavian vein. This separation of the 
 artery from the vein is one of the most important points in its history. + 
 
 The third portion of the sub-clavian, or that extending from the scaleni to the clavicle, 
 corresponds to a triangular space, bounded in front by the stemo-mastoid and anterior 
 scalenus, above by the omo-hyoid, and below by the clavicle : this space is named the 
 lower or clavicular portion of the posterior triangle of the neck, which is bounded in front 
 by the stemo-mastoid, behind by the trapezius, below by the clavicle. In front of, but 
 somewhat lower than the artery, is the clavicle, that bone being separated from the ves- 
 sel by the sub-clavian vein, which is here below and in contact with the artery, and by 
 the sub-clavius muscle ; behind and to the outside of the artery is the brachial plexus 
 of nerves, which surrounds the vessel in the axilla ; it is covered by the deep cervical 
 fascia, the platysma, the superficial fascia, and the skin, and is crossed by the descend- 
 ing cutaneous branches of the cervical plexus, and obliquely by the supra-scapular ar- 
 tery and vein ; below, it rests upon the first rib. 
 
 In consequence of these relations, the sub-clavian artery may be compressed, and the 
 circulation of the upper extremity stopped by forcible depression of the clavicle ; the 
 sub-clavian may be easily felt, compressed, and tied above the clavicle ; and, lastly, it 
 follows that the sharp fragments of a broken clavicle can wound the coats of the artery 
 only after having transfixed the sub-clavius muscle and the sub-clavian vein. 
 
 This artery, moreover, presents individual varieties both in regard to its direction and 
 relations ; it usually rises slightly above the clavicle, but in persons with short necks 
 and high shoulders it is situated deeply under the clavicle, while in those who have long 
 necks and low shoulders it may even slightly raise up the platysma and the skin. But 
 the most important variety is that in which the relations of the sub-clavian with the sca- 
 leni muscles are changed. It is not uncommont to see the sub-clavian artery situated 
 in front of the scalenus anticus, forming immediate relations with the sub-clavian 
 ▼ein.ij 
 
 Collateral Branches. — The sub-clavian artery gives off certain collateral branches, 
 which may be divided into the superior, inferior, and external. The superior are the rer- 
 tebral and the inferior thyroid ; the inferior are the internal mammary and the superior in- 
 tercostal ; the external are the supror scapular, the posterior scapular or transversalis colli, 
 and the deep cervical. 
 
 Besides these, the sub-clavian arteries sometimes give off, near their origin, pericar- 
 diac, thymic, and oesophageal branches ; not unfrequently the left sub-clavian gives ori- 
 gin to the bronchial artery of that side. 
 
 The Vertebral Artery. 
 
 TTie vertebral artery, destined for the cerebro-spinal nervous centre, supplies more 
 particularly the spinal cord, the pons Varolii, the cerebellum, and the posterior portion 
 of the cerebrum. It is the first and largest branch of the sub-clavian, and in some 
 subjects is about equal in size to the continuation of that vessel. A very great inequal- 
 ity in the size of the two vertebrals is rather frequently met with. Morgagni states 
 
 * [It has been observed by Professor R. Quain (Joe. cit.) that the origin of the right sub-clavian is sometimes 
 partially or completely covered by the right carotid, a process of the cervical fascia separating the two vessels.] 
 
 t [Professor Quain has seen, in a few cases, the artery perforating the anterior scalenus ; and it has even 
 been found, by himself and others, anterior to that muscle, and therefore in contact with the vein.] 
 t According to our observation, this is a most rare variety. — Ed. 
 
 ♦ In a case of this kind, which has been communicated to me by M. Demeaux, adjunct of anatomy to the 
 Faculty, there was no brachio-cephalic trunk, but a bi-carotid trunk : the right sub-clavian arose from the de- 
 scending aorta, and went behind the trachea and the oesophagus. (This preparation has been deposited in the 
 museum of the Faculty.) 
 
h^ 
 
 ANGEIOLOGT 
 
 that he has seen the right vertebral four times as large as the left ; I have seen the left 
 vertebral represented by a very small twig. 
 
 The vertebral artery arises (2, fig. 204) from the upper and back part of the sub-clavi- 
 an, at the point where it curves over the apex of the lung ; the left vertebral often ari- 
 ses directly from the arch of the aorta, between the common carotid and sub-clavian of 
 the same side. The right vertebral has been found arising from the point at which the 
 innominate divides into the right common carotid and right sub-clavian. It has also 
 been seen arising by two trunks, both of which sometimes come from the sub-clavian ; 
 and at others, one proceeds from that artery, and the other from the arch of the aorta.* 
 
 Immediately after leaving the sub-clavian, the vertebral artery passes vertically up- 
 ward and a little backward, enters between the transverse processes of the sixth and 
 seventh cervical vertebrae, in order to reach the foramen in the base of the transverse 
 process of the sixth, ascends through the foramina in the transverse processes of the 
 succeeding cervical vertebrae, describing some slight curves in passing from one to an- 
 other. In order to gain the foramen in the axis, it forms a considerable vertical curve 
 between the atlas and that bone ; it then forms a second horizontal curve between the 
 atlas and the occipital bone.t perforates the posterior occipito-atloid ligament and dura 
 mater, and enters the cranium by the foramen magnum. The right and left vertebral 
 arteries turn round the sides of the medulla oblongata, between the hypoglossal and sub- 
 occipital nerves, converge {i i, fig. 208) in front of the medulla, and near the furrow 
 which separates it from the pons Varolii, unite at an acute angle to form the basilar ar- 
 tery {b). The two remarkable curves described by the vertebral artery before it enters 
 the cranium are in accordance with those formed by the internal carotid within the ca- 
 rotid canal and cavernous sinus. I have seen the vertebral very tortuous at the lower 
 part of the neck, before it entered the covered way formed for it by the cervical trans- 
 verse processes. 
 
 Not unfrequently the vertebral artery enters the canal of the transverse processes at 
 the fifth cervical vertebra ; it has occasionally been seen to enter at the fourth, third, and 
 even at the second. It very rarely enters the foramen of the seventh cervical vertebra. 
 
 Relations. — Before entering the foramen of the sixth cervical vertebra, the vertebral 
 artery is situated deeply upon the spine, between the longus colli and the anterior scale- 
 nus, and behind the inferior thyroid artery. The thoracic duct is at first on the inner 
 side, and then in front of the left vertebral artery. From the sixth cervical vertebra to 
 the atlas, it is protected by the canal formed by the series of foramina in the transverse 
 processes, and in the intervals between them by the inter-transversales muscles ; it lies 
 in front of the cervical nerves, but the sub-occipital nerve lies between it and the groove 
 in the atlas. In the intervals between the axis and atlas, and between the atlas and oc- 
 cipital bone, it is in relation with the complexus and trachelo-mastoideus, and with the 
 rectus capitis posticus major and obliquus superior. In those cases where the vertebral 
 artery does not enter the vertebral foramina until it has passed up to the third or second 
 cervical vertebra, it goes upward along the side of the internal carotid artery. In the 
 cranium, it is situated between the basilar surface of ti^e occipital bone and the anterior 
 surface of the medulla oblongata. 
 
 Collateral Branches. — In its course along the canal of the transverse processes, the ver- 
 tebral artery gives off spinal branches, which enter the vertebral canal through the in- 
 ter-vertebral foramina, and are distributed in the same manner as the spinal branches of 
 the intercostal and lumbar arteries. Several of these branches, however, are derived 
 from the ascending cervical artery, and from the praevertebral branches of the ascending 
 pharyngeal. From the two curves formed by the vertebral artery arise a great number 
 of small muscular branches, which are distributed to the deep muscles of the cervical re- 
 gion, and anastomose with branches of the occipital and deep cervical arteries. Among 
 these there is one, sometimes two, which enters the cranium through the foramen mag- 
 num, and is distributed to the dura mater lining the inferior occipital fossa:, and to the 
 falx cerebelli : it is the posterior meningeal artery (rami meninges posteriores, Holler). 
 Soemmering has pointed out a small meningeal branch, which enters the cranium with 
 the first cervical or sub-occipital nerve, and which appears to me to be constant. 
 
 In the cranium, before uniting to form the basilar, the vertebral arteries give off the 
 posterior and anterior spinal arteries, and the inferior cerebellar. 
 
 Spinal Arteries. — These are small branches, remarkable for being extremely slender, 
 and for arising at an obtuse angle, so that they descend in a precisely opposite direction 
 
 * One of the most remarkable varieties of origin of the vertebral artery is the followring, which has been 
 communicated to me by Professor Dubreuil : 
 
 In a woman of forty- five years, the left vertebral arteries arose neither on the right nor on the left side from the 
 corresponding sub-clavian arteries. The left Tertebral took its origin directly from the arch of the aorta, be- 
 tween the left sub-clavian and the left primitive carotid. The right vertebral arose from the right primitive 
 carotid, at the distance of four millimeters from its origin. Both arteries passed upward, in parallel lines, 
 along the vertebral column, as far as the third cervical vertebra, when they entered the vertebral foramina of 
 the transverse processes of this vertebra, having previously given off several small supplementary branches of 
 the ascending cervical arteries. The sub-clavian artery gave here origin only to five collateral branches. 
 
 t Have the curvatures of the vertebral artery any relation to the motions of the head upon the vertebnkl 
 (tolumn ? 
 
THE VERTEBRAL ARTERY. 635 
 
 to the vertebral arteries, which ascend vertically ; they are distinguished into the anterior 
 and the posterior spinal artery. It is incorrect to regard them as continued down to the 
 lower part of the spinal cord : they are so slender, that they can only supply a very small 
 portion of the cord ; in reality, they are nothing more than the commencement of the spi- 
 nal arteries, which are continued through the whole extent of the cord by means of 
 branches given off from the cervical, dorsal, and lumbar arteries. 
 
 The posterior spinal artery arises from the vertebral while that vessel lies upon the 
 side of the medulla oblongata, and sometimes from the inferior cerebellar artery ; it pass- 
 es in a tortuous manner inward, and divides into an ascending branch, which terminates 
 upon the sides of the fourth ventricle, and a descending tortuous branch, which winds 
 along the sides of the posterior surface of the cord, and divides into two twigs, a small 
 one situated before, and a larger one placed behind the posterior roots of the spinal 
 nerves ; around each of these roots they form a network, and, by means of transverse 
 branches, which are twisted on themselves and much interlaced, they communicate with 
 the corresponding branches of the opposite side. Chaussier was therefore incorrect in 
 giving the name of the posterior median artery of the spine to the two posterior spinal ar- 
 teries. Tliese small branches of the vertebral are soon exhausted ; they are continued 
 on each side by branches of the cervical, dorsal, and lumbar spinal arteries, which run 
 upward along the posterior roots of the nerves, and having reached the sides of the cord, 
 divide into ascending and descending branches, which anastomose witli the neighbour- 
 ing vessels, form a network around each pair of nerves, and communicate by tortuous 
 transverse branches with the arteries of the opposite side. 
 
 The anterior spinal artery (m, Jig. 208), which is somewhat larger than the posterior, 
 arises from the vertebral near the basilar, sometimes even from the basilar itself, or from 
 the inferior cerebellar, passes almost vertically inward and downward, in front of the 
 medulla oblongata, and anastomoses in the same manner as the vertebral with its fellow 
 of the opposite side, so as to constitute a median trunk, which is correctly named the 
 anterior median artery of the spine ; it is situated beneath the pearly fibrous band found 
 along the anterior median furrow, and is continued by branches from the cervical, dorsal, 
 and lumbar arteries. 
 
 The anterior, or median spinal artery, therefore, results from the anastomoses of the 
 two anterior spinal branches of the vertebral. In one case there was no artery on the 
 left side, but the right was twice as large as usual. The vessel is of considerable size, 
 until it has passed below the cervical enlargement of the cord, from which point down 
 nearly to the dorsal enlargement it becomes exceedingly delicate ; a little above the last- 
 named enlargement it suddenly increases in size, again gradually diminishes as it ap- 
 proaches the lower end of the spinal cord, and becoming capillary, is prolonged down to 
 the sacrum, together with the fibrous string in which the spinal cord tenninates. 
 
 During its course, this artery receives lateral branches from the ascending cervical 
 and the vertebral in the neck, and from the spinal branches of the intercostal and lum- 
 bar arteries in the back and loins. These branches penetrate the fibrous canal formed 
 by the dura mater around each of the spinal nerves ; become applied to the nervous 
 ganglia, to which they supply branches ; get intermixed with, and follow the course of, 
 the corresponding nerves ; send small twigs backward to the posterior spinal arteries, 
 and terminate in the anterior spinal trunk, at variable angles, similar to those at which 
 the nerves are attached to the spinal cord. 
 
 The re-enforcing spinal branches are not nearly so numerous as the nerves. If the con- 
 dition which I have observed in three subjects be constant, there are three in the cervi- 
 cal region, one or two in the contracted portion of the cord, and one only at the inferior 
 enlargement. This last, which in one case was as large as the ophthalmic artery, reach- 
 ed the cord at a very acute angle ; opposite the median line, it divided into two branch- 
 es, one ascending and very small, the other descending, of considerable size, and form- 
 ing the true continuation of the trunk. 
 
 From the anterior spinal arteries there proceed a great number of twigs, which pass 
 backward into the anterior median furrow, and from thence into the substance of each 
 half of the corresponding portion of the cord ; also some lateral branches, which ramify 
 on the sides of the cord in the pia mater. 
 
 The Inferior and Posterior Cerebellar Arteries. — These (A h) arise from the outer side of 
 the vertebral, and sometimes from the basilar ; they are of considerable size, and often 
 differ in this respect on the two sides. Each of them soon turns round the medulla ob- 
 longata, pursuing a tortuous course, passes between the filaments of origin of the hypo- 
 glossal nerve, runs in front of the roots of the pneiunogastric and glosso-pharyngeal nerves, 
 crosses the restiform body, and reaches the back of the medulla oblongata on one side of 
 the opening of the fourth ventricle ; it then passes backward, between the inferior ver- 
 miform process and lateral lobe of the cerebellum, and divides into two branches : one 
 internal, which continues along the furrow between the vermiform process and lateral 
 lobe, supplies the former, and turns upward into the notch in the posterior margin of the 
 cerebellum ; the other branch is external, and passes outward upon the lower surface of 
 the cerebellum, and divides into a great number of twigs, which may be traced as far as 
 
536 ANGEIOLOGY. 
 
 the circumference of the cerebellum, and which anastomose with those of the superior 
 cerebellar artery. 
 
 The Basilar Trunk. — The basilar trunk (^>) results from the junction or confluence of 
 the two vertebral arteries. It is larger than either of them singly, but its area is not 
 equal to the sum of their areas ; so that, by this arrangement, the passage of the blood 
 is accelerated. It commences opposite the furrow between the medulla oblongata and 
 the pons Varolii, and terminates by bifurcating in front of the anterior border of the pons ; 
 its length, therefore, corresponds to the antero-posterior diameter of the pons, on the 
 median furrow of which it is situated. When the vertebral arteries are displaced to- 
 wards the right side (a very common condition), the basilar trunk passes horizontally or 
 obliquely to the left, so as to reach the median furrow. 
 
 It gives off no branch from its lower surface, which rests upon the basilar groove of 
 the occipital bone. A great number of capillary twigs are detached from its upper sur- 
 face, and enter the pons Varolii. From its sides proceed the anterior inferior cerebellar 
 and the superior cerebellar. 
 
 The anterior and inferior cerebellar arteries {I I) vary much in size in different subjects, 
 and are rarely equal in this respect on the right and left sides : each of them arises from 
 about the middle of the basilar, and occasionally from the vertebral itself, passes out- 
 ward and backward, sometimes behind, and sometimes in front of the sixth nerve, l^lns 
 along the cms crebelli, passes in front of the facial and auditory nerves, and terminates 
 upon the anterior portion of the hemisphere of the cerebellum. 
 
 The superior cerebellar arteries (t t) arise one from each side of the basilar, immedi- 
 ately before it divides into its two terminal branches ; they might, therefore, also be re- 
 garded as terminal branches of that artery, which would thus end by dividing into four 
 branches. Having arisen at a right angle behind the third, or motor oculi nerve, each 
 superior cerebellar artery, accompanied by the fourth or trochlear nerve, turns round the 
 crus cerebri in the groove between it and the pons Varolii, and, having reached the up- 
 per surface of the corresponding crus cerebelli, divides into two branches : one external, 
 which passes outward on the upper surface of the cerebellum, along the anterior half of 
 its circumference ; the other internal, which is directed inward upon the sides of the su- 
 perior vermiform process, or median lobule of the cerebellum, and then subdivides into 
 an antero-posterior branch, which passes from before backward upon the sides of the 
 vemiiform process, as far as the circumference of the cerebellum, upon which it ramifies ; 
 and a transverse branch, which continues the original course of the vessel towards the 
 median line, running between the superior vermiform process and the valve of Vieussens, 
 and being distributed to both. 
 
 The terminal branches of the basilar trunk are the posterior cerebral arteries (n n) ; they 
 arise at variable angles, are directed forward and outward, and then curve backward, so 
 as to turn round the crus cerebri, parallel to the superior cerebellar arteries, from which 
 they are separated by the third or motor oculi nerve. They follow the concave bordei 
 of tiie great transverse fissure of the brain, and, having reached the posterior extrem- 
 ity of the corpus callosum, leave this fissure to pass backward upon the lower surface 
 of the posterior lobe of the cerebrum, where they may be traced as far as the occipital 
 region. Each of the posterior cerebral arteries gives off, immediately after its origin, an 
 immense number of small parallel twigs, which enter the substance of the brain between 
 the anterior crura, whence the name of perforated spot given to that portion of the brain. 
 Just as each posterior cerebral artery curves backward, it receives the communicating 
 artery of Willis (r), which is sometimes very large, and at other times very small. When 
 large, it evidently assists in the formation of the posterior cerebral, which, after its junc- 
 tion with the communicating artery, sometimes becomes doubled or trebled in size. The 
 part performed by the internal carotid in the formation of the posterior cerebral is, there- 
 fore, subject to variety. In certain cases, as I have already stated,, the posterior cere- 
 bral is exclusively derived from it. 
 
 The posterior choroid artery arises from the back part of the posterior cerebral, imme- 
 diately after the junction of that vessel with the communicating artery ; it turns round 
 the crus cerebri, passes above and supplies the tubercula quadrigemina, and terminates 
 in the velum interpositum and choroid plexus. 
 
 As the posterior cerebral artery quits the crus cerebri, it gives off a branch which 
 passes outward and backward, crosses obliquely the long convolution which forms the 
 lateral boundary of the great fissure of the brain, and ramifies upon the lower surface of 
 the cerebrum. Lastly, the posterior cerebral gives off a small constant branch, which 
 may be called the artery of the fascia dentata, to which it is distributed. 
 
 Remarks on the Arteries of the Brain, Cerebellum, and MeduU-a Oblongata. 
 
 The arteries of the encephalon, i. e., of the brain, cerebellum, and medulla, are deri 
 ved from four principal trunks, tw^o anterior, viz., the internal carotids, which arise from 
 the common carotids, and two posterior, viz., the vertebrals, which are branches of the 
 sub-clavian arteries. There are several circumstances to be remarked concerning these 
 vessels, viz., their great size, which is dependant on that of the brain ; their depth from 
 
THE INFERIOR THYROID ARTERY. 637 
 
 the surface before they enter the cranium ; the numerous curves formed by them as they 
 are entering the cranial cavity, the use of vphich is evidently to retard the course of the 
 blood ; the absence of any large collateral branches, the only exception being the oph- 
 thalmic branch of the internal carotid, by the existence of which the circulation in the 
 eye is connected with that in the brain. Another remarkable point concerning these 
 vessels is their anastomoses at the base of the cranium, viz., the anastomosis, or, rath- 
 er, the confluence of the right and left vertebral so as to form the basilar artery ; the 
 anastomosis of the right and left internal carotids by means of the anterior communica- 
 ting artery, which unites the anterior cerebrals, and the anastomosis of the internal ca- 
 rotids with the vertebrals by the communicating arteries of Willis. By these anasto- 
 moses an arterial hexagon (the circle of Willis) is formed, the anterior margins of which 
 correspond with the anterior cerebral arteries, the posterior with the posterior cerebrals, ' 
 and the lateral with the communicating arteries of Willis.* 
 
 From this hexagon, as from a centre, proceed all the arteries of the brain, viz., from 
 the anterior angle, the anterior cerebral arteries ; from the posterior angle, the basilar 
 artery ; from the anterior lateral angle on each side, the middle cerebral ; and from the 
 posterior lateral angle on each side, the posterior cerebral artery 
 
 Owing to the existence of these large anastomotic communications, any one of the 
 four arterial trunks would be sufficient to carry on the circulation in the brain, if the 
 other three were wanting or obliterated The situation of this arterial hexagon between 
 the bones of the cranium and the brain is remarkable, because it explains the alternate 
 movements of elevation and depression seen in the brain when that organ is exposed 
 during life 
 
 It should also be observed, that the arteries of the cerebellum, pons Varolii, and me- 
 dulla oblongata, are derived from the same sources as those of the brain. 
 
 Lastly, as to the mode of distribution of these vessels, it may be remarked, that the 
 arteries of the brain pass over the free surface of one or more convolutions, dip into the 
 sulci between the convolutions, are reflected from one side of them to the other, give 
 off a great number of very small branches, emerge from a given sulcus to regain the 
 surface of the adjacent convolutions, and so on until they are exhausted. The princi- 
 pal arteries of the cerebellum run upon its surface without passing into the sulci, be- 
 tween the laminae, into which they send only very small branches. With some excep- 
 tions, the arteries are reduced to capillary dimensions before they enter the nervous 
 substance. 
 
 The Inferior Thyroid Artery. 
 
 Dissection. — Dissect the muscles of the sub-hyoid region ; follow the branches of the 
 thyroid ; trace the divisions of the ascending cervical artery into the grooves upon the 
 transverse processes of the cervical vertebrae, and into the vertebral canal. 
 
 The inferior thyroid artery. (3, fig. 204) arises from the front of the sub-clavian on a 
 plane anterior to the vertebral, which often comes off exactly opposite to it. It varies 
 remarkably in size and origin, as well as in the branches which it furnishes. It fre- 
 quently arises from the common carotid ; sometimes from the arch of the aorta, between 
 the brachio-cephalic and the left common carotid ; at other times from the brachio-ce 
 phalic itself Lastly, it is occasionally replaced by the thyroid of Neubauer. 
 
 It often commences by a common trunk with the supra-scapular, less frequently with 
 the posterior scapular, and rarely with the internal mammary. 
 
 Its size bears an inverse proportion to that of the superior thyroid of the same side 
 and depends, also, on the presence or absence of a third thyroid. It is larger in infancy 
 than at any other period. In certain cases of goitre it becomes prodigiously developed. 
 Sometimes there is merely a trace of its existence, or it is even altogether wanting. 
 
 Immediately after its origin it passes vertically upward, then descends so as to de- 
 scribe a curve with its concavity directed downward, and again forms another curve 
 with its concavity turned upward, to reach the lower end of the lateral lobe of the thy 
 roid gland, in the interior of which it ramifies. 
 
 Relations. — Behind, it is in relation with the trachea, the oesophagus, and the verte- 
 bral column, being separated from the latter by the praevertebral muscles and the ver- 
 tebral artery. Its relation with the oesophagus is more marked on the left than on the 
 right side, and it is important to bear this fact in mind in performing thq operation of 
 oesophogotomy. In front, its first curve embraces the common carotid, the internal 
 jugular vein, the pneiuntiogeistric, and the great sympathetic nerves. The middle cervi- 
 cal ganglion, when it exists, rests upon it. The second curve embraces the recurrent 
 laryngeal nerve, and is also in relation with the muscles of the sub-hyoid region. It 
 may be remarked, that there is one point in the neck where three arteries come into 
 contact, viz., the common carotid, the inferior thyroid, and the vertebral. 
 
 Collateral Branches. — The inferior thyroid gives off, downward, an oesophageal branch, 
 
 " In a person who died ol apoplexy, Morgagni found a want of communication between the vertebrals and 
 carotids ; and he attributed the apoplexy partly to this circumstance, and partly to the fact that the left ver- 
 tebral arose directly from the arcli of the aorta. 
 
 Yyy 
 
^4|P ANGEIOLO&Y. 
 
 some tracheal branches, and a small brojichial twig. I have seen the right bronchial ar- 
 tery derived from it. It also gives off several muscular branches to the scalenus anti- 
 cus and the praevertebral muscles. The most remarkable of all these is the ascending 
 cervical artery (4), which is of variable size, and is sometimes so large that it may be 
 regarded as resulting from the bifurcation of the inferior thyroid. It passes vertically 
 upward, in front of the scalenus anticus, then in the groove between it and the rectus 
 capitis anticus major, to both of which, as well as to the attachments of the levator an- 
 guli scapulae, it gives some small branches. The most remarkable of its branches, call- 
 ed the cervicorspitial, enter the grooves by which the cervical nerves emerge, run in 
 front of these nerves, and anastomose with the branches of the vertebral artery. I have 
 seen these branches divide into two ramusculi : the one anterior, very small, which 
 passed in front of the vertebral artery, and emerged upon the sides of the body of the 
 vertebra ; the other posterior, which passed between the corresponding nerve and the 
 artery, entered the spinal canal through the intervertebral foramen, and was distributed 
 to the vertebrae, and to the spinal cord and its membranes, in the same manner as the 
 dorsal and lumbar spinal arteries. The praevertebral branch of the ascending pharyn- 
 geal artery sometimes supphes the cervico-spinal branch of the first two intervertebrcd 
 spaces in the cervical region. 
 
 Terminal Branches. — Opposite the lower extremity of the lateral lobe of the thyroid 
 gland, the inferior thyroid artery divides into three branches : of these, one follows the 
 lower border of the gland, another passes to the posterior surface of its lateral lobe, 
 while the third dips between the gland and the trachea, runs along the lower border of 
 the cricoid cartilage, sometimes becomes superficial opposite the isthmus of the thyroid 
 body, and forms an anastomotic arch with its feUow of the opposite side, along the upper 
 margin of that isthmus. 
 
 The Supra-scapular Artery. 
 
 The superior or supra-scapular artery {transversus humeri, 5, fig. 204), destined for the 
 supra- and infra-spinous fossae, and which might also be denominated the cleido-supra- 
 scapular from its course, arises from the front of the sub-clavian below the inferior thy- 
 roid, and often by a common tmnk, either with the posterior scapular, or with the in- 
 ferior thyroid and posterior scapular united, forming what is then called the thyroid axis. 
 It is at first directed vertically downward, then bends horizontally outward, to run along 
 behind the clavicle and gain the upper border of the scapula, where it passes over, very 
 rarely under, the ligament, which converts the coracoid or supra-scapular notch into a 
 foramen, and, being reflected over that ligament, dips into the supra-spinous fossa, and 
 crossing the concave border of the spine of the scapula, enters the infra-spinous fossa, 
 in which situation it terminates {5', fig. 209). 
 
 Relations. — It is concealed at its origin by the stemo-mastoid muscle, and is then sit- 
 uated along the base of the supra-clavicular triangle ; it is in relation in front with the 
 clavicle, following the direction of that bone ; behind, with the sub-clavian artery and 
 the brachial plexus of nerves, which it crosses at right angles ; above, with the deep 
 fascia and the platysma myoides, which separate it from the skin ; and below, with the 
 sub-clavian vein : more externally, it dips under the trapezius, and comes in contact 
 with the supra-scapular nerve, is separated from it at the coracoid notch, and again be- 
 comes applied to it in the supra- and infra-spinous fossae, where it is situated between 
 the muscles of the bone. 
 
 Collateral Branches. — Among a great number of unnamed muscular and cutaneous 
 branches, I would particularly notice, 1. A small thoracic branch, which passes verti- 
 cally downward behind the clavicle, perforates the sub-clavius, and anastomoses with 
 the thoracic arteries. 2. A branch for the trapezius, which is so large that it appears to 
 result from the bifurcation of the artery. It generally arises at the point where the ves- 
 sel dips into the supra-spinous fossa ; at other times it comes off very near the origin of 
 the artery, passes from before backward, turns round the scaleni muscles parallel with 
 the posterior scapular artery, with which one might confound it, and ramifies in the tra- 
 pezius and the supra-spinatus muscles, entering the former at its under, and the latter at 
 its upper surface : some of the branches are distributed to the periosteum of the acromion 
 and to the corresponding integuments. 
 
 Again, in the supra- and infra-spinous fossae it gives off a great number of periosteal, 
 osseous, muscular, and articular branches. In the infra-spinous fossa (5, fig. 209), it 
 forms a free arched anastomosis with the sub-scapular artery, and gives off a branch 
 which runs along the axillary border of the scapula, and anastomoses with the posterior 
 scapular artery at the lower angle of that bone. 
 
 The Posterior Scapular Artery. 
 
 The posterior scapular {transversus cervicis, transvcrsalis colli, 6, fig. 204, 209) is larger 
 than the preceding, and extends from the sub-clavian to the vertebral border of the scap- 
 ula ; it arises from the front of the sub-clavian, sometimes to the inner side of the sea- 
 
THE INTERNAL MAMMARY ARTERY. 639 
 
 leni, sometimes between them, but most commonly on the outer side of those muscles ;* 
 in the first case it often comes off by a common trunk with the inferior thyroid, and in 
 the two other cases by a common trunk with the supra-scapular. It passes transversely 
 and in a slightly tortuous manner outward, through the nerves of the brachial plexus, 
 and sometimes through the scalenus posticus, and curves backward towards the poste- 
 rior superior angle of the scapula. Then, opposite the levator anguli scapulae, it divides 
 into an ascending and a descending- branch. The ascending or cervical branch, the super- 
 Jicial cervical artery of authors, passes beneath the trapezius, and divides into a great 
 number of twigs, which ramify in that muscle, in the levator anguli scapulae, and in the 
 splenius. The descending branch forms the posterior scapular artery, properly so called 
 (a. Jig. 209), and may be regarded as the continuation of the vessel ; it turns round the 
 posterior superior angle of the scapula, beneath the levator Fig. 209. 
 
 anguli,. passes vertically downward along the vertebral bor- ^ 
 
 der of that bone, and terminates at the inferior angle by an- , ^\ 
 astomosing with the sub-scapular artery, a branch of the ax- , ^A 
 illary, and with the supra-scapular, already described. '^^^jS^^»— ^.^^ 
 
 Relations. — It is superficial in the first part of its course, ••',:^^^^^^~^^^ 
 during which it traverses the supra-clavicular triangle hor- -V>^^^^^^^ 
 izontally, being merely covered by the cervical fascia, the '^^^^ib^W^tk 
 platysma myoides, and the omo-hyoid ; and hence, doubt- ^^^-■C/Wt^^^>\ 
 less, the name superficial cervical, which has been given to -' v~T^^^^^^\ 
 it by some authors. + It is but rarely that the posterior ' /-^•^^'P^^^^^w 
 scapular turns round the posterior scalenus and the brach- , ' / -s5^y^;J^W^w//^ 
 ial plexus, without passing between the nerves of the plex- .^j!^yj/^ fms^mWli^w 
 us, which it traverses at variable heights. As it proceeds \ ' v^ it0^i^MJMj]r' 
 backward, it is protected by the trapezius ; and, lastly, ^- it'^^^^^^^oi-.JssJ 
 
 along the vertebral border of the scapula, it lies between the rhomboideus and the serra- 
 tus magnus 
 
 Its collateral branches are destined for the following muscles : the trapezius, sc£ilenus 
 posticus, levator anguU scapulae, splenius, supra- and infra-spinati, sub-scapularis, rhom- 
 boideus, and serratus magnus. 
 
 The Internal Mammary Artery. 
 
 The internal mammary, or internal thoracic artery, not so remarkable for its size, 
 which is less than that of the vertebral, as for its length and the number of its branches, 
 arises (7, fig. 204) from the sub-clavian opposite the inferior thyroid, and behind the supra- 
 scapular. Few arteries are less variable in their origin. The only varieties which have 
 been observed are those in which it arises from the brachio-cephalic, from the arch of 
 the aorta, or from a common trunk with the inferior thyroid. Immediately after its ori- 
 gin, it passes vertically doAvnward behind the inner end of the clavicle, enters the thorax, 
 crosses obliquely behind the cartilage of the first rib, and bends a little inward to run 
 along the first portion of the sternum, below which it resumes its vertical direction, par- 
 allel to the border of that bone, as low down as the sixth rib, where it divides into an 
 internal and an external branch. 
 
 Relations. — It is situated in front of the scalenus anticus, and is covered at its origin 
 by the phrenic nerve, which crosses it very obliquely, in order to reach its inner side ; it 
 corresponds to the inner end of the clavicle, from which it ie separated by the brachio- 
 cephalic vein ; it is then placed behind the costal cartilages and the intercostal muscles, 
 in front of the pleura, from which it is separated by the triangularis sterni. It is situa- 
 ted about two lines to the outer side of the margin of the sternum, so that a cutting in- 
 strument may be carried into the thorax along that bone without injuring the internal 
 mammary ; the name sub-sternal is, therefore, not at all appUcable to this artery, which 
 would be better named sub-chondro-costal. 
 
 Collateral Branches. — These are very numerous ; they may be divided into the poste- 
 rior, anterior, and external. The posterior branches are, the thymic or anterior mediastinals, 
 and, lower down, the superior phrenic, an extremely small artery, which runs along the 
 phrenic nerve, is situated, like it, between the pericardium and the corresponding layer 
 of the mediastinum, and reaches and is ramified in the diaphragm. Bichat has seen the 
 superior phrenic artery as large as the internal mammary itself. 
 
 The external branches are the anterior intercostals. Their number corresponds with 
 that of the intercostal spaces : they are small in the first two, and gradually increase or 
 diminish according to the length of the corresponding spaces. I have seen the common 
 trunk for the third intercostal space so large, that it appeared like a bifurcation of the 
 mammary. There are generally two branches for each intercostal space : one, which 
 runs along the lower margin of the rib above, and the other along the upper margin of 
 the rib below. These two branches sometimes arise separately from the mammary, 
 
 * In the last case, those authors who describe the sub-clavian as terminating between the scaleni, say that 
 the posterior scapular arises from the axillary artery, 
 t [It is the ascending- or cervical branch only that is named superficial cervical.] 
 
540 ANGEIOLOGY. 
 
 sometimes by a common trunk ; as they arise above the level of the space for which 
 they are intended, it follows that they pass obliquely behind the costal cartilages. The 
 anterior intercostals inosculate with the aortic or posterior intercostals, so that it is 
 sometimes impossible to determine the limits between these two sets of vessels. In 
 some subjects they form a communicating arch of uniform caliber, extending between 
 the internal mammary and the thoracic aorta. 
 
 The anterior branches are superficial, and correspond in number to the intercostal spa- 
 ces ; they arise from the internal mammary, pass directly from behind forward, through 
 the corresponding intercostal space, and divide into cutaneous and muscular branches, 
 both of which sets curve outward, the muscular branches beneath the pectoralis major, 
 in which they ramify, and the cutaneous branches beneath the skin. Tlie anterior 
 branches of the first three spaces are distributed to the mammary gland. In females re- 
 cently delivered, and in nurses, these branches become extremely large, especially the 
 second, which I have seen as large as the radial artery, and very tortuous. Before per- 
 forating the intercostal muscles, the anterior branches send some periosteal twigs be- 
 hind the sternum, some of which penetrate the bone directly, while others ramify on 
 the periosteum. 
 
 Terminal Branches. — Of the two terminal branches, the internal, and smaller, contin- 
 ues the original course of the artery, passes behind the rectus abdominis muscle, enters 
 its sheath, and then divides into a great number of branches ; some of these are lost in 
 this muscle by anastomosing with the capillary divisions of the epigastric, while the oth- 
 ers emerge from the sheath of the rectus by special openings, and are distributed to the 
 broad muscles of the abdomen, and to the integuments. Before leaving the cartilage of 
 the seventh rib, it gives off a small twig, which passes inward upon the side of the en- 
 siform cartilage, and forms an anastomotic arch with its fellow of the opposite side, in 
 front of that cartilage. The anastomosis of this artery with the epigastric, which has 
 been known from the very earliest periods, and afforded the ancients an explanation of 
 the intimate physiological connexions between the genital organs and mammary glands, 
 is accomplished in the usual manner of capillary communication. 
 
 The external terminal branch, as far as distribution is concerned, is the continuation of 
 the internal mammary. It is directed downward and outward, behind the cartilages of 
 the seventh, eighth, ninth, tenth, and eleventh ribs, which it crosses obhquely, and ter- 
 minates opposite the last intercostal space. During its course, it gives off the anterior 
 intercostals of the corresponding spaces, two for each space, sometimes only one, which 
 immediately subdivides. These intercostals diminish gradually in size as the spaces 
 decrease in length, and are distributed precisely as the anterior intercostal branches of 
 the internal mammary itself The external terminal branch, and also the internal, while 
 passing through the diaphragm near its costal attachments, give off a great number of 
 branches to that muscle, and hence the name musculo-phrenic, given by Haller to the 
 external division, which, indeed, furnishes many more branches to the diaphragm than 
 the internal. 
 
 The Deep Cervical Artery. 
 
 Dissection. — Seek at first for the artery behind the scalenus anticus, between the 
 transverse process of the seventh cervical vertebra and the first rib ; trace it, both to its 
 termination, between the complexus and semi-spinalis colli, and towards its origin, with- 
 in the scaleni. 
 
 The posterior, or deep cervical, comes off deeply from the upper and back part of the 
 sub-clavian, on the same plane as the vertebral, to the outside of which it is situated. 
 Very often it arises by a common trunk with the first intercostal. It passes at first up- 
 ward and backward, then bends outward behind the scalenus anticus to dip between the 
 transverse process of the seventh cervical vertebra and the first rib. I have never seen 
 it pass between the transverse processes of the sixth and seventh cervical vertebrae, 
 though for this purpose I have examined forty subjects.* 
 
 After leaving the inter-transverse space, the deep cervical artery divides into two 
 branches : one descending, which I have been able to trace as far as the middle of the 
 dorsal region, between the long muscles of the back ; the other ascending, which passes 
 up between the complexus and the semi-spinalis colli, in which it terminates, and anas- 
 tomoses with the occipital and vertebral arteries. 
 
 The Superior Intercostal Arteries. 
 Dissection. — This artery can only be dissected from the internal surface of the thorax. 
 For this purpose it is necessary to saw through the thorax vertically. The artery must 
 be exposed by removing the pleura from the two upper ribs and intercostal muscles. 
 
 * This relation is so constant, that, even in cases where there is a supernumerary cervical rib, the deep 
 cervical artery passes betwreen this supernumerary rib and the first dorsal rib. Some students having called 
 me to examine a subject in which this artery was wanting, I sought in vain for it between the first rib and 
 the transverse process of the last cervical vertebra, and then perceived that there was a cervical rib, between 
 which and the first dorsal rib the artery was found. 
 
 [In 264 observations, Professor Quain met with this variety in the course of the artery four times, and also 
 other peculiarities.] 
 
THE AXILLABY ARTERY. 
 
 The superior intercostal artery, intended for the two or three superior intercostal spa- 
 ces, sometimes only for the first, varies in size according to the extent of its distribu- 
 tion. It comes off from the lower and back part of the sub-clavian, near the deep cer- 
 vical, and sometimes by a common trunK with it. It descends, m a tortuous manner, m 
 front of the neck of the first, and then of t'ne second rib, on the outside of the first dorsal 
 ganglion of the sympathetic nerve, and terminates in the second intercostal space, like 
 an aortic intercostal artery ; sometimes it anastomoses freely with the first of the aortic 
 intercostals. It gives off in each space a dorso-spirud branch, and an intercostal branch, 
 properly so called. It is not rare to find the intercostal branch wanting in the first space : 
 in all cases it is extremely small. 
 
 The Axillaky Artery. 
 
 Dissection. — In order to prepare the axillary, as well as all the other arteries of the 
 upper extremity, it is sufficient to dissect the muscles 
 carefully, at the same time preserving aU the branches 
 which are met with, and tracing them to their origin. 
 
 The axillary artery {a a', fig. 210) is that part of the 
 artery of the upper extremity which intervenes be- 
 tween the sub-clavian and the brachial. Its limits, 
 which are entirely artificial, are the clavicle,* on the 
 onp hand, and the lower border of the pectoralis major 
 on the other. It traverses the axilla diagonally, and 
 bends opposite the neck of the humerus, so as to be- 
 come continuous with the brachial artery. Its upper 
 part rests upon the thorax, and its lower upon the hu- 
 merus ; it is not very tortuous, so that in forcible ab- 
 duction of the arm it may be stretched even to lacera- 
 tion. Its direction corresponds pretty nearly with the 
 cellular interval so generally existing between the 
 sternal and the clavicular portions of the pectoralis 
 major, or, rather, with an imaginary line, extending 
 from the junction of the outer with the two inner thirds 
 of the clavicle to the inner side of the neck of the hu- 
 merus. 
 
 Relations. — From the importance necessarily attach- 
 ed to an accurate knowledge of the relations of this ar- 
 tery, we shall consider them in the four aspects of the 
 vessel. 
 
 In front, the axillary artery is in relation from above 
 downward with the sub-clavius muscle, a process of 
 the deep cervical fascia intervening between them ; 
 then with the costo-coracoid ligament and the pecto- 
 ralis major ; next with the pectoralis minor ; below 
 this muscle, with the pectoralis major again ; and, last- 
 ly, with the coraco-brachialis. In a subject where the 
 pectoralis major had no clavicular insertions, that por- 
 tion of the axillary artery which is intermediate be- 
 tween the clavicle and the superior border of the pec- 
 toralis minor, was separated from the skin only by the 
 platysma myoides. Behind, it is in relation with the 
 cellular interval between the sub-scapularis and serra- 
 tus magnus ; lower down, with the teres major and 
 latissimus dorsi. On the inside, it rests at first upon 
 the first rib and the first intercostal space ; it next 
 leaves the thorax, from which it is separated by the 
 hollow of the armpit, and its inner side is then in re- 
 lation with the skin which forms the outer wall of the 
 armpit, and with the subjacent fascia. On the outside, 
 it is at first embraced by the concave surface of the 
 coracoid process, and it is then placed opposite the head of the humerus, from which it 
 is separated by the sub-scapularis muscle 
 
 Relations with the Axillary Vein and Nerves. — Immediately below the clavicle, tne axdlary 
 vein is situated on the inner side of, and at some distance from, the artery ; lower down, 
 the vein lies upon the artery. The cephahc and acromial veins pass in front of the artery. 
 
 Immediately below the clavicle, the entire brachial plexus is situated on the outer side 
 
 * Those authors who consider the sub-clavian as terminating between the scaleni, describe the axillary aa 
 commencing at the same point 
 
 [The axillary artery is commonly said, in this country, to commence at the lower border of the first rib (a), 
 and to terminate at the lower border of the conjoined tendons (a') of the latissimus dorsi and teres major 
 muscles.] 
 
542 ' ^ ANGEIOLOGY. 
 
 of the artery, only one thoracic nerve crossing in front of it. Under the pectoralis minor 
 the artery is surrounded by the plexus ; it is at first embraced by the external and inter- 
 nal roots of the median nerve, which meet in the form of a V opening upward ; lower 
 down, it is placed between the external cutaneous nerve on the outer side, the median 
 in front, the internal cutaneous and the ulnar on its inner side, and the radial, or muscu- 
 lo-spiral, and the circumflex behind. In order to expose the artery in the axilla, the ves- 
 sel may be sought for between the median and ulnar nerves. 
 
 In consequence of these relations, wounds of the axilla may be very serious ; com- 
 pression may be applied to the axillary artery, either by forcibly depressing the clavicle 
 against the first intercostal space and second rib, or by placing the finger upon the ves- 
 sel in the axilla, and pressing it against the head of the humerus ; a ligature may be ap- 
 plied to this artery, either under the clavicle above the pectoralis minor, or in the axilla ; 
 lastly, the artery may be torn from extreme violence in attempting to reduce a dislocation.* 
 
 Collateral Branches. — The axillary gives off five branches, viz., the acromio-thoracic, 
 alpove the pectoralis minor ; the inferior thoracic, or external mammary, below the pecto- 
 ralis minor ; the inferior scapular, and the anterior and posterior circumflex arteries, op- 
 posite the neck of the humerus. 
 
 The Acromial and Superior Thoracic Arteries. 
 
 Under the name of acromio-thoracic I include two arteries, the acromial and the supe- 
 rior thoracic, which almost always arise by a common trunk, which is detached at right 
 angles from the inner side of the axillary artery immediately above the pectoralis minor, 
 then crosses the upper border of that muscle at right angles, and immediately divides 
 into the two above-named branches. 
 
 The thoracic branch passes downward and inward, and subdivides {b b) between the two 
 pectoral muscles, both of which it supplies, but especially the lesser. Some branches 
 perforate the pectoralis major, and are distributed to the skin and the mamma. 
 
 The acromial branch subdivides into two others : a descending or deltoid branch (c), 
 which enters the cellular interval between the pectoralis major and the deltoid, traverses 
 it throughout, and is distributed to these two muscles, but especially to the deltoid ; it 
 is accompanied by the cephalic vein : the second is a transverse or acromial branch {d), 
 which runs horizontally outward, passes over the apex, and sometimes over the base of 
 the coracoid process, then upon the coraco-acromial ligament, and runs along the outer 
 third of the anterior border of the clavicle. It is covered in the whole of its course by 
 the deltoid, to which it is in a great measure distributed. Some twigs terminate in the 
 skin over the acromion. This acromial branch terminates near the acromio-claviculax 
 articulation : sometimes one of its divisions closely follows the anterior border of the 
 clavicle. 
 
 The Inferior or Long Thoracic Artery. 
 
 The inferior thoracic, long thoracic, or external mammary artery (e, fig. 210), is much lar- 
 ger than the acromial thoracic, and sometimes arises by a common trunk with it or with 
 the sub-scapular ; it is given off from the axillary below the pectoralis minor, passes 
 downward and forward upon the side of the thorax, between the pectoralis major and 
 serratus magnus, then between the serratus and the skin, and terminates at about the 
 sixth intercostal space. During this course it gives off a great number of branchest to 
 the lymphatic glands in the axilla, to the sub-scapularis, pectoralis major, and serratus 
 magnus muscles, to the second, third, fourth, fifth, and sixth 'intercostal spaces, to the 
 mamma, and to the skin. Not unfrequently the inferior thoracic partially supplies the 
 place of the sub-scapular artery, in which case it is as large as that vessel. 
 
 The Sub-scapular Artery. 
 The inferior, common, or sub-scapular artery (/), the largest branch of the axillary, 
 arises near the lower part of the head of the humerus opposite the lower border of the 
 sub-scapular muscle, sometimes by itself, sometimes by a common trunk with the poste- 
 rior circumflex, the long thoracic, or the deep humeral artery ; in the last case it is as 
 large as, perhaps even larger than, the brachial. At its origin, which is from the outer 
 aspect of the axillary, it has the musculo-spiral nerve to its inner side, and the principal 
 orig;in of the median on its outer side ; it passes in a tortuous manner downward and out- 
 ward along the lower border of the sub-scapularis muscle, parallel with the teres major, 
 and beneath the head of the humerus,^ furnishes large branches to all these muscles, 
 and having arrived below the insertion of the sub-scapularis, divides into two branches, 
 a descending or thoracic, and a scapular, properly so called. 
 
 * I hare seen two cases of rupture of the axillary artery from attempts to reduce old dislocations. 
 
 t [These branches represent the alar thoracic artery, and sometimes arise directly from the axillary, behind 
 the pectoralis minor, or from the sub-scapular.] 
 
 t The relation of the sub-scapular artery to the head of the humerus appears to me to be important. In 
 abduction thi« artery is much stretched, and I am surprised that it has not been torn in same cases of luxation ; 
 on the contrary, the circumflex artery, and, therefore, the circumflex nerve, appear to me to be much less lia 
 ble to be stretched during abduction. Nevertheless, it is certain that the circumflex nerve has been lacerated 
 in some dislocations of the humerus, because they have been followed by paralysis of the deltoid muscle. 
 
THE BRACHIAL ARTERY. 543 
 
 The descending or thoracic branch (g), which is often given off by the inferior or long 
 thoracic, passes downward and forward near the axillary border of the scapula, parallel 
 with and behind the long thoracic, and divides into a great number of large branches, 
 some of which enter the latissimus dorsi, several penetrate the serratus magnuseven as 
 far as the lowest portion of that muscle, while others turn round the lower angle of the 
 scapula, and anastomose with the following or scapular branch, and with the posterior 
 scapular derived from the sub-clavian. 
 
 The scapular branch (i), properly so called, proceeds along the lower border of the sub- 
 scapularis muscle, in front of the long head of the triceps, and having reached below the 
 scapular attachment of the triceps, divides into three branches : an anterior or sub-scapu- 
 lar branch, which dips into the sub-scapular fossa below the muscle, and expands into a 
 great number of branches, the highest of which are distributed to the capsule of the 
 shoulder-joint ; an infra-spinous branch (Jb,fig. 209), which turns round the axillary border 
 of the scapula, runs between the muscle and the infra-spinous fossa, and anastomoses, 
 by a considerable branch, with the termination of the supra-scapular artery ; a median 
 branch (c,fig. 209), which continues in the original course of the vessel, runs along the 
 axillary border of the scapula, between the teres major and minor, then becomes poste- 
 rior, and terminates by anastomosing again upon the lower angle of the scapula with the 
 thoracic branch of this artery, and with the infra-spinous branches of the supra-scapular. 
 
 The Posterior Circumflex Artery. 
 
 The posterior circumflex artery (Z, fig. 210) arises from the back of the axillary opposite 
 the sub-scapular, which it sometimes equals in size. It passes horizontally backward, 
 between the sub-scapularis above and the teres major below, turns inward round the 
 surgical neck of the humerus, passing first between the internal head of the triceps and 
 the teres minor, then between the long head of the triceps and the bone, and finally (Jl,fig. 
 209) under the deltoid, to the deep surface of which it is applied ; it always turns round 
 so as to describe three fourths of a circle, and thus reaches the anterior and outer aspect 
 of the humerus, and is lost in the deltoid by anastomosing with the deltoid branches of 
 the acromio-thoracic artery. In the whole of its course it is accompanied by the cir- 
 cumflex vein and the circumflex nerve. As it turns round the bone, the posterior cir- 
 cumflex gives off some articular and periosteal branches, which pass to the capsular lig- 
 ament of the shoulder-joint, and to the periosteum of the humerus. 
 
 The Anterior Circumjlex Artery. 
 The anterior circumflex, a small artery {n,fig. 210), sometimes represented by several 
 branches, arises from the axillary in front of the posterior circumflex, and often by a 
 common trunk with it. It passes horizontally outward above the conjoined tendons of 
 the latissimus dorsi and teres major, covered by the coraco-brachialis and the short head 
 of the biceps, runs beneath the tendon of the long head of the biceps, turns round the 
 neck of the humerus, crosses the bicipital groove at right angles, being held down by 
 the synovial membrane, and divides into an ascending and a descending branch. The 
 Jatter presents nothing remarkable ; but the ascending branch, having reached the up- 
 per part of the groove, anastomoses with the osseous branch of the acromial artery, 
 and is lost in the head of the humerus, which it penetrates at one or more points. The 
 anterior circumflex is, therefore, intended for the humerus, its periosteum, and the syno- 
 vial membrane of the groove. Sometimes there are several anterior circumflex arteries, 
 which enter the substance of the deltoid muscle. 
 
 The Brachial Akteky. 
 
 The brachial or humeral artery (a' h,fig. 210) is that portion of the artery of the upper 
 extremity which extends from the lower border of the axilla to the point of its bifurca- 
 tion at the upper part of the forearm. It passes downward, and a little forward and 
 outward, so that it is situated on the inner side of the humerus above, and in front of it 
 below. The absence of any bendings in this artery explains the possibility of its being 
 torn from extreme extension of the forearm in dislocations of the elbow, &c.* 
 
 The relations of the brachial artery require to be examined separately along the arm, 
 and in front of the elbow-joint. 
 
 Along the arm, the artery is in relation, in front, with the coraco-brachialis and the in- 
 ner margin of the biceps, which may be regarded as the satellite muscle of the artery : 
 in emaciated subjects the biceps does not cover the artery, which is then situated im- 
 mediately under the fascia ; behind, it is in relation with the triceps, and then with the 
 brachialis anticus ; on the inner side, with the fascia of the arm, which separates it from 
 the skin ; on the outer side, with the coraco-brachialis, then with the inner side of the hu- 
 merus, from which it is separated by the tendon of the coraco-brachialis, and in the rest 
 of its extent with the cellular interval between the biceps and the brachialis anticus. 
 The brachial artery is enclosed in a fibrous sheath, which is common to it and the me- 
 
 * In old subjects, the humeral artery is almost always tortuous, and sometimes these windings are so re- 
 markable that the artery is sub-aponeurotic during a portion of its course. 
 
6)44 ANGEIOLOGY. 
 
 dian nerve. The following are its relations with the veins and nerves : the principal 
 brachial vein is situated on its inner side ; another smaller vein is on its outer side : 
 both are in contact with the artery, which they separate from the nerves, and they are 
 connected by several transverse branches, which embrace the artery. 
 
 The median nerve is situated in front of the artery, excepting above, where it is on 
 its outer side, and below, near the elbow, where it passes to its inner side ; the median 
 nerve sometimes crosses behind the artery.* The ulnar nerve is placed on the inner 
 side of the artery above, then passes behind it, and is lodged in a separate sheath. The 
 musculo-spiral nerve is situated, together with the deep humeral artery, at first behind 
 the brachial, but soon leaves it to turn round the humerus ; lastly, the internal cutane- 
 ous follows the same course as the vessel, crossing it slightly from before backward. 
 
 From these relations, it follows that the vessel may be most eificaciously compressed 
 from within outward, against the inner surface of the humerus, and also that it may be 
 tied in any part of its course. 
 
 At the bend of the elbow, the brachial artery occupies the middle of the articulation ; it 
 is superficial in front, where it is only separated from the skin by the fascia and tendi- 
 nous expansion of the biceps, and by the median basilic vein, which crosses it at a very 
 acute angle ; behind, it rests upon the brachialis anticus, by which it is separated from 
 the elbow-joint ; on its inner side is the median nerve and pronator teres muscle, and, 
 on its outside, the tendon of the biceps, over which it soon crosses, and, farther outward, 
 the supinator longus. 
 
 In consequence of the superficial position of the brachial artery at the bend of the el- 
 bow, and from its relations with the median basilic vein and the elbow-joint, it follows 
 that this artery may be easily compressed, may be wounded in the operation of vene- 
 section, and may be lacerated in dislocations of the joint, t 
 
 Collateral Branches. — These may be divided into the external and anterior, and the inter- 
 nal and posterior. 
 
 The external and anterior are very numerous, and are intended for the coraco-brachia- 
 lis and biceps, which they penetrate at different heights, and also for the brachialis an- 
 ticus. A very remarkable branch, which appears to me to be constant, viz., the deltoid, 
 passes transversely in front of the humerus, beneath the coraco-brachialis and the biceps, 
 and terminates partly in the deltoid at its humeral insertion, and partly in the brachialis 
 anticus. The internal and posterior branches are small, excepting those which enter the 
 brachialis anticus directly : I have seen them all arise from the axillary by a large branch 
 given off from a common trunk with the sub-scapular and the posterior circumflex arteries. 
 
 Whatever may be their mode of origin, four of these collateral branches are remark- 
 able for their regular distribution, viz., the deep humeral, the internal collateral, the super- 
 ficial branch for the internal portion of the triceps, and the superficial branch for the brachi- 
 alis anticus. The two former only have received particular names. 
 
 The deep humeral artery {profunda superior, k, fig. 210), called aJso the external collateral, 
 from its terminating on the outer side of the articulation of the elbow, arises from the 
 brachial, opposite the lower border of the teres major. It occasionally comes off by 
 a common trunk with the posterior circumflex, which, in that case, arises from the 
 brachial instead of the axillary artery. It passes downward and backward, gains the 
 groove for the musculo-spiral nerve, and traverses the whole extent of that groove to- 
 gether with the nerve. In this part of its course it is situated between the triceps mus- 
 cle and the humerus, as it turns round the posterior surface of that bone ; below the in- 
 sertion of the deltoid it emerges from the groove, between the brachialis anticus and the 
 triceps, and divides into a deep branch, which continues with the nerve, and a superficial 
 branch. The former is distributed essentially to the triceps muscle, and sometimes 
 comes off directly from the brachied ; it passes vertically downward in the substance 
 of the triceps, supplies its internal and external portions, and terminates in them by 
 anastomosing freely with the collateral branches situated around the elbow-joint. The 
 superficial branch perforates the external head of the triceps, and the external inter-mus- 
 cular septum, along which it descends vertically to the back of the epicondyle, or external 
 condyle of the humerus, where it anastomoses with the interosseous recurrent artery. 
 
 The internal or ulnar collateral artery {profunda inferior, m, figs. 210, 211) is much 
 smaller than the external collateral, from which it is sometimes derived ; it is often 
 double. It usually arises at a variable height from the lower part of the brachial, some- 
 times passes transversely inward, and sometimes proceeds in a tortuous manner down- 
 ward before becoming transverse, and then divides into two branches : one anterior, which 
 is distributed to the brachialis anticus, the muscles attached to the epitrochlea or internal 
 condyle of the humerus, and the periosteum upon that process ; the other posterior, which 
 perforates the internal intermuscular septum, and divides into muscular branches for the 
 
 * Dubreuil has seen that arrangement in three cases ; and M. Chassignac has met with it twice last winter. 
 
 t I have seen this artery lacerated in a case of luxation forward of the humerus on the forearm, in conse- 
 quence of a fall from a horse upon the wrist. The lower extremity of the humerus had torn the brachialis 
 anticus, the artery and the skin through which it had passed. A hemorrhage, followed by syncope, took 
 place at the moment of the accident. The patient having been carried to her residence in this swoon, the 
 reduction was accomjdished, the hemorrhage did not return, and the cure was as perfect as possible. 
 
THE BRACHIAL AATEEY. 545 
 
 triceps ; into periosteal and osseous branches, which pass transversely in front of the 
 triceps, and anastomose with the interosseous recurrent ; and into a descending branch, 
 which accompanies the ulnar nerve, and anastomoses with the posterior ulnar recurrent. 
 
 The superficial branch for the internal portion of the triceps is remarkable for its size and 
 length ; it arises from the brachial, inunediately below the profunda superior, from which 
 also it is rather frequently derived, and passes vertically downward applied to the idnar 
 nerve. It is at first situated in front of the internal intermuscular septum, then perfo- 
 rates it, accompanied by the idnar nerve, and, passing backward between the epitrochlea 
 and the olecranon, aneistomoses with the posterior ulnar recurrent. 
 
 The superficial branch for the braehialis anticus arises from the brachial artery at the 
 same height as the preceding, runs along the inner side of the braehialis anticus, grad- 
 ually diminishing in size down to the lower part of the arm, where it anastomoses with 
 the internal collateral artery.* 
 
 The terminal branches of the brachial are the radial (jp,figs. 210, 211) and ulnar (g) ar- 
 teries. The bifurcation of the brachial artery into the radial and ulnar usually takes 
 place below the bend of the elbow, sometimes on a level with it, but rather frequently 
 above the articular line ; in the latter case, the bifurcation has been observed to occur 
 sometimes at the lower third or at the middle of the arm, sometimes at the junction of 
 the upper with the two lower thirds, and sometimes in the axilla itself, the radial and 
 ulnar arteries immediately succeeding to the axillary. In these cases, one division of 
 the artery, generally the radial, is sub-cutaneous, while the ulnar assumes the ordinary 
 relations of the brachial ; but the reverse of this may take place ; and, lastly, the radial 
 and the ulnar have both been found sub-cutaneous. Not unfrequently, the radial artery, 
 at its origin, is the inner branch of the bifurcation, and then crosses the ulnar at a very 
 acute angle, in order to reach the radius. Besides these anomalies resulting from va- 
 rieties in the point of bifurcation, there is yet another, in which a premature division takes 
 place into two branches, one of which forms the interosseous artery, and the other the 
 brachial, which has its usual arrangements ; at other times, instead of a bifurcation, 
 only a very slender branch is given off, and terminates in the ulnar, which in that case 
 arises by two roots. 
 
 The frequency of high divisions of the humeral artery require that the practical con- 
 siderations to which these give rise should be taught. If, therefore, a hemorrhage by 
 the arteries of the forearm should not yield to a ligature of the humeral artery, we should, 
 with M. Danyau, suspect the high division of the humeral artery, and search for the 
 other branch. 
 
 Here follows the minute description of three rare varieties which I have exhibited at 
 the Anatomical Society. From the inferior part of the axillary artery arose a slender ar- 
 tery, which first coursed all along the humeral artery, on the inside of which it was situ- 
 ated ; it then crossed this vessel by passing before it at the union of the two superior with 
 the inferior third of the arm, and finally joined the radial artery opposite the bicipital tu- 
 berosity of the radius. 
 
 At the bend of the elbow, this artery, which might be considered as a slender branch 
 of origin of the radial artery, occupied the same relations as the humeral artery, and 
 was situated below the aponeurotic expansion of the biceps, while the trunk of the hu- 
 meral artery was not placed under this expansion, but below the tendon of the biceps. 
 It was behind this tendon, a little above its insertion into the radius, that the humeral 
 artery was divided into radial and ulnar ; the radial, instead of coursing directly down- 
 ward, described a curve with the concavity inward ; and it was with the lower part of 
 this curve that the long and feeble branch coming from the axillary artery united. 
 
 I have met, again, a similar anomaly, with this difference, that the long and slender 
 arterial branch, instead of going to the radial, anastomosed with the ulnar. This variety 
 may be considered as a mode of anastomosis between the upper and the lower part of 
 an arterial trunk, a mode of anastomosis by a collateral canal, unusual in the arterial, but 
 very frequent in the venous system. 
 
 In a case where one of the branches of the high division was the interosseous artery, 
 and the other the common trunk of the radial and ulnar arteries, the respective relations 
 of these vessels were as follows : 
 
 The humeral dichotomic division took place below the hollow of the axilla. One of 
 the branches was the common trunk of the interosseous arteries, which first followed 
 the usual course of the humeral artery, then crossed, at a very acute angle, the other 
 branch by passing behind it, coursed obliquely downward and outward, and finally reach- 
 ed the external border of the tendon of the biceps. Having been sub-aponeurotic so far, 
 it now dipped under the pronator teres, gave off the radial and ulnar recurrent branches. 
 iQd terminated as the interosseous arteries terminate. 
 
 ITie other branch constituted the common trunk of the radial and cubital arteries ; 
 
 * [These two superficial braaches are frequently represented in their distributioo by a sing-le branch, nailed 
 the anastomotic artery (u,figs. 210, 211), which arises from the brachial, about two inches above the elbow. 
 
 The nutritious artery of the humerus is small, but constant : it as-ises from the outer side of the brachial, or 
 one of its collateral branches, passes downward, perforates the insertion of the coraco-lwachialis muscle, and 
 enters the oblique foramen in the inner side of the humerus, to ramify in the aicduilary c«nal of that bone 1 
 
 Z 2 Z 
 
546 AN6EI0L06T. 
 
 sub- aponeurotic, like the preceding, it reached the anterior side of the epitrochlea, and 
 divided into two secondary branches : one internal, which was the ulnar, a little tortu- 
 ous, coursed downward as far as the annular carpal ligament ; the other external, which 
 was the radial, passed obliquely downward and outward as far as the radial insertion of 
 the pronator teres, when it became vertical. During their whole course, the radial and 
 ulnar arteries were sub-aponeurotic. 
 
 I have been on the point of opening the radial artery at the bend of the arm, in a 
 case where it lay over the superficial tendon of the biceps.* 
 
 A knowledge of these anomahes, both in reference to the point of bifurcation and to 
 the new relations of the parts, is extremely important to the surgeon. 
 
 The Radial Artery and its Branches. 
 
 Dissection. — The radial artery in the forearm is completely exposed by dissecting the 
 supinator longus ; the carpal portion of the artery by dissecting the tendons of the 
 thumb opposite the vnrist ; the palmar portion by dividing all the flexor tendons in the 
 palm. It is, therefore, advisable to postpone the examination of the palmar portion of 
 the artery until the ulnar has been studied. 
 
 The raAial artery (j),figs. 210, 211), the outer of the two branches into which the brach 
 ial divides, is more superficial and smaller than the ulnar ; it extends from the point 
 of bifurcation of the brachial down to the peilm of the hand. Sometimes the radial turns 
 backward, after having reached the lower third of the forearm, and remains sub-cutane- 
 ous until it dips between the first and second metacarpal bones ; its place in front of the 
 lower part of the radius is then supplied by the radio-palmar artery or superficialis volaj, 
 which is extremely small. It is very common to find the radial artery of one arm larger 
 than that of the other ; in one case I found both radials wanting in front of the lower 
 part of the radius. 
 
 Tlie radial artery is at first directed downward, and somewhat obliquely outward, like 
 the brachial, with the direction of which it corresponds ; it then descends vertically as 
 far as the lower end of the radius, turns round the anterior surface and apex of the sty- 
 loid process, to gain the outer side of the carpus, and passes obliquely downward and 
 backward, to reach the upper part of the first interosseous space ; there it turns abrupt- 
 ly forward, between the upper extremities of the first and second metacarpal bones, 
 passing between the two origins of the first dorsal interosseous muscle, enters the palm 
 of the hand, and runs almost transversely inward, to form the deep palmar arch {b, Jig. 
 211). The radial artery is frequently tortuous at the lower part of the forearm. From 
 the long course and the direction of the radied, it may be divided into three portions, 
 corresponding to the forearm, the wrist, and the palm of the hand. 
 
 The first jiortion of the radial artery, viz., that situated in the forearm, has the following re- 
 lations : In front, with the inner border of the supinator longus, which overlaps it, especial- 
 ly above ; in the rest of its extent it lies beneath the fascia. In emaciated subjects the su- 
 pinator longus is narrow, and this part of the artery is sub-aponeurotic in its whole extent. 
 
 Behind, it corresponds to the anterior surface of the radius, from which it is separated 
 above by the supinator brevis ; lower down by the pronator teres, and by the radial ori- 
 gins of the flexor sublimis and flexor longus poUicis ; still lower by the pronator quadra- 
 tus, below which it rests directly upon the inferior portion of the radius. The superficial 
 position of the radial artery, and the support afforded it by the bone, are the reasons 
 why it is chosen for examining the pulse. 
 
 On the inner side, it is in relation with the pronator teres, then with the tendon of the 
 flexor carpi radialis, along which it runs, and which is on a plane anterior to it ; so that 
 the contraction of this muscle, by causing its tendon to project, renders the pulsations 
 of the vessel more difficult to be felt. 
 
 On the outer side, it is in relation with the supinator longus, and in the middle part of 
 its course with the radial nerve (the continuation of the musculo-spiral), which is situ- 
 ated at some distance from it, both above and below, and has a separate fibrous sheath. 
 
 Of the collateral branches of the radial artery in the forearm, only three require a special 
 description, viz., the anterior radial recurrent, the anterior carpal branch, and the radio- 
 palmar artery. 
 
 The anterior radial recurrent artery {r,figs. 210, 211) is given off from the back part, 
 and immediately below the origin of the radial. It is very large in some subjects, in- 
 deed as large as the radial itself : it descends a little, and then turning upward, so as to 
 describe a curve with its convexity directed downward, it ascends between the supina- 
 tor longus and the brachialis anticus, in order to anastomose with that part of the pro- 
 
 * The editor, engaged as he has been, for thirty years, in teaching anatomy, has had very extensive oppor- 
 tunities of observing varieties in the origins of the radial and ulnar arteries ; and as the result of these, he 
 would state as a general rule, liable to very few exceptions, 1st. When the radial arises prematurely, it pass- 
 es, like the humeral, under the aponeurotic expansion of the biceps muscle. 
 
 2d. When the ulnar arises above the elbow, it passes superficially above this aponeurosis, being placed sub- 
 cutaneous in connexion with th« veins. 
 
 The editor believes, that in the majority of cases where an artery is wounded in performing the operation of 
 jloodletting at the bend of the arm, the vessel injured is the ulnar, which has arisen prematurely. In several 
 cases where he has been called on to operate for aneurism produced by this accident, he has found this to he 
 the case. 
 
THE RADIAL ARTERY. 549 
 
 fimda superior which forms the external collateral branch of the elbow. I have seen 
 this recurrent artery arise from the ulnar. 
 
 From the convexity of the arch described by the radial recurrent, a great number of 
 branches proceed obliquely downward and outward, and are distributed to all the raus 
 cles on the external aspect of the forearm, viz., the long and short supinators, and the 
 two radial extensors. One of these branches passes transversely between the long supi- 
 nator and the long radial extensor, to anastomose on the outer condyle with the profun- 
 da artery ; others pass between the radius and the muscles attached to it, ramifying in 
 the extensor muscles of the forearm, and anastomose with the posterior interosseous 
 artery derived from the ulnar. 
 
 The anterior carpal branch of the radial artery is a small branch {a, fig. 211) which 
 passes transversely inward at the lower margin of the pronator quadratus muscle, and 
 anastomoses with a similar branch from the ulnar artery. 
 
 The radio-palmar or superficial palmar artery {superficialis voIcf,, s, fig. 210) arises at an 
 acute angle from the inner side of the radial, at the point where that vessel turns out- 
 ward to pass over the carpus. Sometimes its origin is situated at the junction of the 
 lower with the two upper thirds of the forearm. It varies much in its size and distribu- 
 tion ; most commonly it passes vertically downward, on a level with the anterior liga- 
 ment of the carpus, perforates the origin of the short abductor of the thumb, and anasto- 
 moses with the extremity of the superficial palmar arch {t) of the ulnar (g). Several 
 branches arise from its convexity, and are distributed to the muscles and integuments 
 of the ball of the thumb. The radio-palmar branch is frequently very small, is entirely 
 lost in those muscles, and does not assist in the formation of the superficial palmar arch. 
 On the contrary, it is often so large that it may be regarded as formed by the bifurcation 
 of the radial, and then assists as much as the ulnar in forming the superficial palmar 
 arch. In some cases in which the superficial palmar arch did not exist, I have seen the 
 radio-palmar give origin to the internal collateral artery of the thumb, both collateral ar- 
 teries of the index, and the external collateral of the middle finger, the ulnar artery fur- 
 nishing the collaterals of the other fingers. In one case, a transverse branch, resembling 
 the anterior communicating artery of the brain, formed the anastomosis between the ra- 
 dio-palmar and the ulnar arteries. 
 
 The second or carpal portion of the radial artery extends from the styloid process of the 
 radius to the upper part of the first interosseous space. Closely applied to the ligaments 
 and bones of the carpus, it passes at first obliquely downward and inward, and then be- 
 comes vertical as it dips into the interosseous space, to pass between the two heads of 
 the first dorsal interosseous muscle. It is well protected on the outer side of the carpus 
 by the projecting tendons of the two extensors and the long abductor of the thumb, edl 
 of which cross it obliquely, and separate it from the skin ; but between the tendons of 
 the long abductor of the thumb and the long radial extensor it becomes sub-aponeurotic, 
 and therefore very superficial. In this short course it gives off several branches. 
 
 The dorsal carpal branch of the radial artery, more remarkable for its constancy and 
 the mode of its distribution than for its size, which is inconsiderable, arises opposite the 
 articulation of the two rows of carpal bones, passes transversely inward, and terminates 
 either by being lost in the adjacent parts, or by anastomosing with the corresponding 
 branch of the ulnar artery. From the arch thus formed proceed certain ascending branch- 
 es, which anastomose with twigs from the anterior interosseous artery, sometimes ap- 
 pearing to form the termination of that vessel, which, as we shall presently describe, be- 
 comes posterior at the lower part of the forearm ; and also some descending branches, of 
 very variable size, which, having reached the upper part of the third and fourth interos- 
 seous spaces in peirticular, anastomose with the perforating branches of the deep palmar 
 arch, and form ope of the origins of the small twigs, which are named the dorsal interos- 
 seous arteries of those spaces. 
 
 The dorsal interosseous branch for the second space, known also as the dorsal metacarpal 
 branch of the radial artery, is sometimes so large that it seems to be a continuation of 
 the radial, and at other times very small, and, as it were, a mere vestige. It often ari- 
 ses by a common trunk with the dorsal carpal branch just described ; it runs along the 
 dorsal surface of the second interosseous space, and, having reached the lower part of 
 it, gives superficial dorsal arteries to the index and middle fingers, and then bends for 
 ward between the heads of the second and third metacarpal bones, to anastomose witli 
 that digital branch of the superficial palmar arch which gives off the internal collateral 
 artery of the index, and the external collateral artery of the middle finger.* 
 
 The interosseous artery of the first space is so large that it is described as formed by the 
 bifurcation of the radial : it arises from that artery between the first and second meta- 
 carpal bonesj and sometimes runs along the dorsal aspect of the first interosseous space, 
 and at others between the first dorsal interosseous muscle and the adductor poUicis ; in 
 
 * [Three small branches, two of which usually arise by a common trunk, are given off from the radial ar- 
 tery near the dorsal aspect of the head of the first metacarpal bone ; two of them form the superficial dorsal 
 arteries of the two sides of the thumb {dorsales pollids), while the other is the dorsal artery of the radial side 
 •f the indtx finger {dorsahs indicis).'i 
 
$4^ AN6ET0LO6Y. 
 
 «ther case, when it reaches the lower part of the space, it divides into two branches, 
 which may arise separately from the carpal portion of the radial artery, as in^^. 211, 
 and which constitute the internal collateral artery of the thumb and the external collateral 
 artery of the index finger (x). The external collateral artery of the thumb, sometimes deri- 
 ved from the preceding, or even from the extremity of the superficial palmar arch, cross- 
 es the muscles of the ball of the thumb obliquely, to reach the outer side of its metacar- 
 po-phalangal articulation (v,fig. 210), and runs along the outer border of the thumb.* 
 
 The Deep Palmar Arch. 
 
 The third or 'palmar portion of the radial artery constitutes the dee'p palmar arch (i, fig. 
 211), which is completed by inosculating with a branch of the ulnar, in the same man- 
 ner as we have seen the superficial palmar arch of the ulnar artery completed by a branch 
 of the radial. This arch is situated deeply across the front of the metacarpal bones, im- 
 mediately below their upper extremities ; it rests immediately upon them and the inter- 
 osseous muscles, and is therefore subjacent to all the nerves, tendons, and muscles (ex- 
 cept the interosseous) in the palm of the hand. The deep palmar arch describes a slight 
 curve, the convexity of which is directed downward. I have seen the palmar arch form- 
 ed by the dorsal artery of the second interosseous space, which then dipped between the 
 upper ends of the second and third metacarpal bones. 
 
 The deep palmar arch gives off very short superior or ascending branches {recurrentes), 
 which are lost in front of the carpus, anastomosing with the anterior carpal branches of 
 the radial and ulnar arteries ; also some descending or palmar interosseous arteries (d d, 
 interosseae volares, Holler), three or four in number, which descend vertically along the 
 interosseous spaces, and anastomose with the descending digital branches (cut across in 
 fig. 211) of the superficial palmar arch, either opposite or above their bifurcation into 
 the collateral arteries of the fingers. The size of the palmar interosseous arteries is ex- 
 tremely variable, as well as that of the deep palmar arch itself; it bears an inverse pro- 
 portion to that of the superficial palmar arch and its branches. The relative size of the 
 difierent palmar interosseous arteries, also, varies much ; most generally the first is the 
 largest, at other times the second, and occasionally the third. 
 
 The deep palmar arch also gives off the posterior or perforating branches (c c). These 
 are three in number, and form for the second, third, and fourth interosseous spaces what 
 the radial itself is for the first, with this difference, that the radial perforates the first 
 space from behind forward, while these perforating branches traverse the corresponding 
 spaces from before backward. They arise from behind the deep palmar arch, and imme- 
 diately perforate the upper part of the interosseous spaces in a straight line, and having 
 reached the dorsal aspect of the hand, generally anastomose with the corresponding dor- 
 sal interosseous arteries, which, in a great number of cases, are formed entirely by these 
 perforating branches. In some subjects, the dorsal interosseous arteries result from the 
 anastomoses of the perforating arteries with the interosseous arteries derived from the 
 dorsal carpal arch formed by the dorsal carpal branches of the radial and ulnar arteries ; 
 they pass vertically downward on the dorsal surface of the interosseous spaces, and hav- 
 ing reached their lower parts, anastomose with the descending digital branches of the 
 superficial palmar arch, and thus assist in the formation of the collateral arteries of thp 
 fingers. 
 
 The Ulnar Artery and its Branches. 
 
 The ulnar artery {g,figs. 210, 211), which is larger than the radial, leaves that vessel 
 at a very acute angle, passes at first downward, inward, and backward, in front of the 
 ulna, describing a slight curve, the convexity of which is directed upward and inward, and 
 then descends vertically. Having arrived at the wrist, it is placed on the outer or radi- 
 al side of the pisiform bone, in front of the annular ligament of the carpus, and then 
 enters the pahn of the hand,'where it describes beneath the palmar fascia an arch, which 
 has its convexity turned downward, and is named the superficial palmar arch {t,fig. 210 ; 
 removed in^^. 211). 
 
 The relations of the ulnar artery must be separately examined in the forearm and in 
 the hand. 
 
 In the forearm, it is at first covered by the thick bundle of muscles which are attached 
 to the inner condyle of the humerus, and also by the median nerve, from which it is sep- 
 arated by that part of the pronator teres which arises from the coronoid process ; it is 
 then covered by the flexor sublimis, and finally by the fascia and skin ; the tendon of the 
 flexor carpi ulnaris is upon its inner side, and that of the flexor sublimis on its outer : 
 these two tendons, by their projection, occasion an interval between the artery and the 
 skin. It is in relation behind with the brachialis anticus, the flexor profundus digitorum, 
 and the pronator quadratus. The ulnar nerve is applied to the inner side of the artery 
 
 * [The two collateral arteries of the thumb, and the external collateral of the index finger, frequently arise 
 in a different manner from that described above : thus, the two arteries for the thumb may take origin from a 
 common trunk, which is then named the great or principal artery of the thumb (magna vel princeps pollicis) , 
 while the artery for the index finger arises separately, and is named the radial collateral artery of the index 
 Unger (radialis indicis).1 
 
THE ULNAR ARTERY. 
 
 mi 
 
 I!^. 211. 
 
 at the point where the vessel becomes vertical, and accompanies it as 
 far as the hand. The median nerve is situated on its inner side at the 
 bend of the elbow, but afterward becomes anterior, and then external 
 to it. In some cases of high division of the humeral artery, the ulnar 
 has been found immediately under the fascia in its whole length. 
 
 In the hand, it is at first situated on the outer or radial side of the 
 pisiform bone, and then in front of the hook-like process of the unci- 
 form bone ; finally, where it forms the superficial palmar arch, it is 
 entirely sub-aponeurotic. 
 
 In the forearm, the ulnar artery gives off a great number of un- 
 named collateral branches, which are divided into internal, external, 
 anterior, and posterior, and are distributed to the muscles and integ- 
 uments. Four branches, however, require special notice, viz., in 
 the forearm, the common trunk of the ulnar recurrents, the interosseous 
 artery, the branch for the median nerve, and the anterior artery of the 
 carpus; in the palm of the hand, the ulnar artery gives off the collet- 
 erai arteries of the fingers. 
 
 The anterior arid posterior ulnar recurrent arteries generally arise 
 by a common trunk, which is given off from the back of the highest 
 portion of the ulnar artery, passes transversely inward, and divides 
 into two branches — an anterior and a posterior. The former, or an- 
 terior ulnar recurrent artery {e,fig. 211), passes between the brachialis 
 anticus and pronator teres, gives branches to all the muscles attach- 
 ed to the inner condyle, and anastomoses with the internal collateral 
 branch from the brachial. The other branch, the posterior ulnar re- 
 current, is larger than the anterior, runs behind the muscles arising 
 from the inner condyle, is then situated between that condyle and 
 the olecranon, passes between the two origins of the flexor carpi 
 ulnaris in front of the ulnar nerve, anastomoses freely with the in- 
 ternal collateral branch of the brachial artery and with the interosseous recurrent, and 
 contributes to form an arterial network upon the back of the elbow-joint. The branch 
 given off by the posterior ulnar recurrent to the ulnar nerve deserves to be pointed out ; 
 it may be traced from below upward, along that nerve, and anastomoses with the other 
 branches given off to the same nerve from the brachial artery. 
 
 The interosseous artery is so large that it appears to be the result of a bifurcation of the 
 ulnar, and is described as such by many anatomists ; it comes off from the back of the 
 ulnar, immediately below the trunk of the recurrents, on a level with the bicipital tuber- 
 osity of the radius ; it not unfrequently arises from the radial. Lastly, in several cases 
 of high division, either of the brachial or of the axillary artery, the interosseous has been 
 found to constitute one of the branches of the bifurcation, the other branch being the 
 common trunk of the radial and ulnar arteries. 
 
 Immediately after its origin, the interosseous passes directly backward, and divides 
 into two branches of almost equal size, which are named, from their distribution, the an- 
 terior and posterior interosseous. 
 
 The anterior interosseous if fig- 211) descends vertically in front of the interosseous 
 ligament, and is held down to it by a layer of fibrous tissue ;* it is placed behind the 
 flexor profundus digitorum and the flexor longus pollicis, in the cellular interval between 
 these muscles. Having reached the upper borders of the pronator quadratus, it passes 
 between that muscle and the interosseous ligament, rests upon the latter, and perforates 
 it towards its lower part ; having thus reached the back of the forearm, the anterior in- 
 terosseous descends upon the dorsal surface of the carpus, and terminates by anastomo- 
 sing with the dorsal carpal branches of the radial and ulnar. While perforating the in- 
 terosseous ligament behind the pronator quadratus, the artery almost always gives off a 
 small twig, which descends perpendicularly to join the arch formed by the anterior ar- 
 teries of the carpus. 
 
 In one case where the radial artery was exceedingly small, indeed in a rudimentary 
 state, its place was supplied by the anterior interosseous ; which, after having passed 
 behind the pronator quadratus, escaped forward under the lower border of that muscle, 
 and passed transversely outward, to anastomose with the rudimentary radial artery, 
 which, thus re-enforced, immediately assumed its usual size. 
 
 During its course, the interosseous artery only gives off some small branches to the 
 front of the forearm, among which the artery of the median nerve deserves special notice ; 
 but several large branches are detached in succession from its posterior aspect, and im- 
 mediately perforate the interosseous ligament : they are called the perforating arteries of 
 the forearm, and are distributed to the deep layer of muscles on the back of the forearna. 
 I have seen one of these run along the posterior surface of the interosseous ligament, in 
 the same manner as the anterior interosseous artery. 
 
 * After amputation of the forearm, the interosseous artery becomes retracted between thi« fibrous layer and 
 the interosseous ligament ; and it is hence so difficult in some cases to place a ligature upon it, that it haa 
 been recommended to divide the inte"-=«^"~ '■ -•nent for a short distance. 
 
ANGEIOLOGY. 
 
 The artery of the median nerve is remarkable for its constancy and its length ; it comes 
 , off from the front of the anterior interosseous artery, reaches the posterior surface of the 
 median nerve, penetrates it, and then runs downward along its inner side. I have seen 
 the artery of the median nerve very large, and anast9mosing with the superficial pahnar 
 ar<3h. It has also been found continuous with the brachial artery, and supplying the 
 place of both the radial and ulnar, which were in a rudimentary state. 
 
 The posterior interosseous artery is generally smaller than the anterior ; it perforates 
 the interosseous ligament opposite the lower border of the supinator brevis, and imme- 
 diately gives off an ascending branch, the interosseous recurrent ; it then descends be- 
 tween the deep and superficial layer of muscles on the back of the forearm, and divides 
 into a number of branches, which are distributed to those muscles, but especially to the 
 superficial layer.* 
 
 The interosseous recurrent is a branch of the posterior interosseous, of such size that it 
 may be regarded as resulting from the bifurcation of that artery : it passes vertically up- 
 ward, having the anconeous and the extensor carpi ulnaris behind it, and the supinator 
 brevis in front of it ; it runs behind the inner condyle, and anastomoses on the outer side 
 of the elbow-joint with the cutaneous, muscular, and periosteal divisions of the superior 
 profunda artery, the external collateral branch of the brachial 
 
 The anterior carpal branch of the ulnar artery is a small twig, which arises opposite the 
 lower borders of the pronator quadratus, passes between the tendon of the flexor carpi 
 ulnaris and the ulna, and anastomoses with a similar branch from the radial, to form the 
 anterior carpal arch, from which several branches descend to reach the interosseous 
 muscles, and those of the ball of the thumb - 
 
 The Superficial Palmar Arch. 
 
 Opposite the articulation between the two rows of carpal bones, and before it forms 
 the superficial palmar arch, the ulnar artery gives off a deep branch backward, called the 
 radio-cubital, or communicating artery {y,fig- 210), which dips between the short abduc- 
 tor and short flexor of the little finger, then passes outward between the short flexor and 
 opponens, to anastomose with and complete the deep palmar arch. This artery is some- 
 times so large that it may be regarded as formed by the bifurcation of the ulnar 
 
 The superficial palmar arch (t,fig. 210), which constitutes the termination of the ulnar, 
 gives off no important branch from its upper or concave side. Four or five diverging digi- 
 tal branches pass from its lower or convex side, and constitute the collateral arteries ol 
 the fingers. 
 
 The digital branches (w u u) are distinguished as the first, second, third, and fourth, 
 proceeding from within outward. The first reaches the inner or ulnar border of the lit- 
 tle finger, and constitutes its internal collateral artery ; the second runs along the fourth 
 interosseous space, and divides into the external collateral artery of the little finger, and the 
 internal collateral artery of the ring finger ; the third runs along the third interosseous space, 
 and supplies the external collateral artery of the ring finger and the internal collateral artery 
 of the middle finger ; the fourth runs in the second interosseous space, and gives the ex- 
 ternal collateral artery of the middle finger and the internal collateral artery of the index fin- 
 ger. It is very rare to find the external collateral artery of the index finger (x), and the 
 internal collateral of the thumb derived from the superficial palmar arch ; and still more 
 rare to see the external collateral artery of the thumb (r) given off by that arch. 
 
 Whatever varieties there may be in the arteries of the palm of the hand,J in reference 
 to the share which the radial and ulnar respectively take in the formation of the collat- 
 eral arteries of the fingers, the following general facts are apparent in their distribution : 
 The size of the superficial and deep palmar arches respectively are always inversely pro- 
 portioned to each other ; the communication between the two arches takes place not 
 only directly between the arches themselves, but also indirectly in a great number of 
 points by their branches ; all the descending branches of the deep palmar arch anasto- 
 mose with the angle of bifurcation of the descending branches of the superficial palmar 
 arch : those from the deep arch are sometimes smaller, sometimes larger than those 
 
 * Some branches may oe traced as far aa the carpus. 
 
 t [There are usually two other branches given from the ulnar in the vrrist : the first is a dorsal metacarpal 
 branch, which arises above the anterior carpal, runs under the tendon of the flexor ulnaris, turns round the 
 ulna to reach the back of the carpus, anastomoses with the dorsal metacarpal branch of the radial, and sends 
 a twig along the fifth metacarpal bone, to form the superficial dorsal artery of the little finger. The second 
 branch of the ulnar in this situation may arise with the one just described ; it is a posterior or dorsal carpal 
 branch, which passes backward, and anastomoses beneath the extensor tendons with the dorsal carpal branch 
 of the radial artery.] 
 
 i In one case the superficial palmar arch was formed in the most regular manner by the radial and the ul- 
 nar arteries, which concurred in its formation by two perfectly equal trunks, and gave off the collateral branch- 
 es to all the fingers except the external collateral of the thumb, the internal collateral of the index, and the 
 external collateral of the middle finger. 
 
 The deep palmar arch, very small in comparison with the superficial palmar arch, which was very consider- 
 able, was formed as usual. It gave off the external collateral of the thumb and the common trunk of the in- 
 ternal collateral of the index, and the external collateral of the middle finger. This common trunk was the 
 continuation of the non-flexed portion of the radial artery. The radial artery in this case was much larger 
 than the ulnar. 
 
REMARKS ON THE ARTERIES OF THE UPPER EXTREMITY. 551 
 
 trom the superficial arch ; they are rarely of the same size, but always bear an inverse 
 ratio to them ; the bifurcation of each digital branch of the superficial pahnar arch takes 
 place two or three lines below the metacarpo-phalangal articulation, opposite the junc- 
 tion of the body with the upper end of the first phalanx ; the collateral arteries of the 
 fingers are situated upon the anterior aspect of the phalanges, on each side of the sheath 
 of the flexor tendons ; they give off dorsal and palmar branches, and anastomose with 
 each other in front of the body of the phalanges by small transverse branches ; having 
 reached the middle of the last phalanx, they anastomose in an arch, from the convexity 
 of which a great number of anterior branches pass to the skin, over the last phalanx, and 
 some dorsal branches to the matrix of the nail ; one of these branches runs along the 
 curved adherent border of the nail. 
 
 The termination of the superficial palmar arch is subject to variety: thus, it terminates 
 either by anastomosing with the radio-palmar or superficialis volae, of the same size as 
 itself, or by receiving a very small radio-palmar branch, and being prolonged so as to con- 
 stitute the common trunk of the internal collateral artery of the thumb, and the external 
 collateral artery of the index finger ; or else it terminates in the external collateral of 
 that finger ; or, lastly, after having given off the internal collateral of the thumb and the 
 external collateral of the fore-finger, it ends in the external collateral of the thumb. At 
 other times, again, there is no superficial palmar arch properly so called, and the ulnar 
 artery terminates by furnishing the collaterals of the little and ring fingers, and the in- 
 ternal collateral of the middle finger, the other collaterals being derived from the radio- 
 palmar, which is then very large. In certain cases, a very small transverse branch forms 
 the communication between the radial and the ulnar arteries. 
 
 General Remarks on the Arteries of the Upper Extremity. 
 
 A single trunk, which may be called the brachial trunk, supplies the whole of the up- 
 per extremity ; it forms, in succession, the sub-clavian, the axillary, and the brachial ar- 
 tery, which latter bifurcates near the bend of the elbow into the radial and ulnar arteries : 
 these form the palmar arteries, from which the arteries of the fingers take their origin. 
 
 The difference in the origin of the right and left brachial trunks has been considered 
 to account for the difference in strength between the two arms ; and the different size 
 of the two vessels has also been supposed to be connected with the same fact, which, 
 however, in reality, depends upon the more frequent exercise of the right than of the 
 left arm. 
 
 The brachial trunk is not exclusively distributed to the upper extremity, but supplies 
 the most dissimilar parts ; a fact which shows that the conditions of origin, which have 
 so great an influence in regard to nerves, are altogether without importance in reference 
 to the arteries. Thus, the brachial trunk sends branches to the following parts : the ver- 
 tebral artery to the brain, the cerebellum, the pons varolii, the medulla oblongata, and 
 the spinal cord ; the inferior thyroid artery, to the thyroid gland, the larynx, the trachea, 
 the oesophagus, and sometimes the bronchi ; the internal mammary and thoracic arteries, 
 to the corresponding manrnia ; and the same arteries, together with the superior inter- 
 costal, to the parietes of the thorax and abdomen ; the ascending cervical, to the praever- 
 tebral muscles and the spine ; and, lastly, the deep cervical, sub-scapular, and posterior 
 scapular arteries, to the superficial and deep muscles of the back of the neck. 
 
 Setting aside those branches which do not belong to the upper extremity properly so 
 c^ed, we find that, during its course along the limb, the artery always occupies the as- 
 pect of flexion, which is at the same time the position where it can be best protected ; 
 and that, for this purpose, it is directed from the axilla to the bend of the elbow : we 
 find, also, that it gives off a great number of anastomotic branches around the articula- 
 tions, and thus establishes a collateral circulation, through which the blood can pass 
 when the principal artery is obliterated. This anastomosis, and, consequently, the col- 
 lateral circulation, is effected by the cutaneous, muscular, and periosteal branches, and 
 even by those distributed to the nerves. Thus, along the clavicle, we find the acromio- 
 thoracic in front, and the supra-scapular or transversus humeri behind ; around the scap- 
 ula there are the supra-scapular on the upper border, the posterior scapular on the ver- 
 tebral border, and the sub-scapular on the axillary border ; so that that bone is complete- 
 ly surrounded by an anastomotictriangle. 
 
 Around the elbow-joint are the external and internal collateral branches of the brach- 
 ial artery, and the radial, ulnar, and interosseous recurrents. 
 
 Around the wrist we find the anterior and posterior carpal arteries, and also anasto- 
 motic arches around the metacarpo-phalangal and phalangal articulations. 
 
 On comparing the size and number of the arteries of the arm and forearm with the 
 size and number of the arteries of the hand, it will be seen that the latter has greatly 
 the advantage : indeed, in this part of the body, there is an unusual distribution of the 
 arterial system into a deep and a superficial set of vessels, precisely as is the case with 
 the veins. Why is this \ Is it not extremely probable that, as the deep veins are in- 
 tended to supply the place of the superficial, when the circulation in the latter is for a 
 time impeded, so in the hand the arteries are arranged in a similar manner, because the 
 
bS2 ANGEIOLOGY. 
 
 superficial circulation is liable to be interrupted by pressure from grasping hard bodies 
 firmly in the hand for a longer or shorter period 1 and is it not for the same reason that 
 the superficial system derived from the ulnar artery has so many communications with 
 the deep system given off from the radial 1 
 
 It is virorthy of remark that the radial, which is the superficial eirtery of the forearm, 
 becomes deep-seated in the hand ; and that the ulnar, which is deep-seated in the fore- 
 arm, becomes superficial in the hand. 
 
 The great quantity of blood circulated through the hand is connected with the active 
 use of that part, in the ahnost constant exercise of the sense of touch, and in prehension 
 
 ARTERIES ARISING FROM THE TERMINATION OF THE AORTA 
 
 Enumeration. — The Middle Sacral. — The Common Iliacs. — The Internal Iliac, or Hypogas- 
 tric — the Umbilical — the Vesical — the Middle Hemorrhoidal — the Uterine — the Vaginal — 
 the Obturator — the Uio-lumbar — the Lateral Sacral — the Glutceal — the Sciatic — the Inter- 
 nal Pudic. — Summary of the Distribution of the Internal Iliac. — Artery of the Lower Ex- 
 tremity. — The External Iliac — the Epigastric — the Circumflex Iliac. — The Femoral — the 
 Superficial Epigastric — the External Pudic — the Muscular — the Deep Femoral, its Cir- 
 cumflex and Perforating Branches. — The Popliteal and its Collateral Branches. — The An- 
 terior Tibial and the Dorsal Artery of the Foot. — The Tibio-peroneal — Peroneal — Poste- 
 rior Tibial, and the Internal and External Plantar. — Comparison between the Arteries of 
 the Upper and Lower Extremities. 
 
 The arteries arising from the termination of the aorta are the middle sacral and the 
 two common iliac arteries. 
 
 The Middle Sacral Artery. 
 
 The middle or anterior sacral artery {n,fig. 199), the small median artery of the sacrum, 
 arises from the lower and back part of the aorta, a little above its termination. Like 
 the aorta, it is a single vessel, and seems to be the continuation of it, as far as direction 
 is concerned ; which, indeed, is really the case in such animals as are provided with a 
 tail. Sometimes, but rarely, it arises from the left common iliac, or the last lumbar ar- 
 tery. I have seen it arise by a common trunk with the two lower lumbar arteries.* It 
 passes vertically downward in front of the fifth lumbar vertebra, the sacrum and the 
 coccyx being closely applied to them all. It is situated in the median line at its origin, 
 but sometimes deviates to one side or the other. In size it is scarcely equal to one of 
 the lumbar arteries, and it gradually diminishes from its origin to the first bone of the 
 coccyx, towards the apex of which it terminates in a very variable manner. 
 
 The size of the middle sacral is generally inversely proportioned to that of the lowest 
 lumbar arteries. When the aorta divides higher than ordinarily, and the last lumbar is 
 given off from the middle sacral, the last-named artery is of course unusually large. 
 
 During its course, the middle sacral gives off, opposite the fifth lumbar and each of 
 the sacral vertebrae, a right and left lateral branch, which correspond with the series of 
 intercostal and lumbar arteries. The two lumbar branches are generally small, but are 
 very large when the fifth lumbar arteries are neither furnished by the aorta, nor by the 
 fourth lumbar, nor by the ilio-lumbar. The lateral branches given off upon the sacrum 
 pass transversely outward, supply twigs to the periosteum and bone, and anastomose 
 with the lateral sacral, the place of which they sometimes supply within the interior of 
 the sacral canal. 
 
 The middle sacral having become very slender near the base of the coccyx, bifurcates 
 in order to form an anastomotic arch with the right and left lateral sacral arteries. I 
 have seen its lower end divided into three branches, of which the median was prolonged 
 as far as the tip of the coccyx, while the lateral branches anastomosed with the lateral 
 sacral arteries. 
 
 The Common Iliac Aeteeies. 
 The primitive or common iliac arteries (i i, figs. 199, 212), the two branches into which 
 the aorta subdivides, commence opposite the lower margin of the fourth lumbar vertebra, 
 and terminate by bifurcating opposite the base of the sacrum ; they separate from each 
 other at an acute angle, pass obliquely downward and outward, and form the two sides 
 of an isosceles triangle, the base of which corresponds with the transverse diameter of 
 the fifth lumbar vertebra. These arteries are generally straight, but not unfrequently 
 they are tortuous in aged persons. In the adult they are about two inches long, the 
 right being rather longer than the left, from the position of the aorta ; but they are often 
 much shorter, on account of their bifurcating higher than usual. Meckel has remarked 
 that this premature bifurcation is more common on the left than on the right side. In 
 a specimen deposited in the museum of the Ecole de Medecine, the right common iliac 
 
 * 1 have geen the middle sacral artery arise from the renal artery. In this case, the renal artery came frtau 
 the angle of bifurcation of tke aorta. 
 
THE INTERNAL ILIAC ARTERY. 553 
 
 is entirely wanting ; the aorta dividing into three branches, two on the right, viz., the in- 
 ternal and external iliacs, and one on the left, viz., the common iliac, which is distributed 
 in the usual manner. In this case the descending aorta resembled, to a certain extent, 
 the ascending aorta, and, like it, gave off three trunks 
 
 Relations. — They are covered by, and loosely connected with, the peritoneum ; they 
 are crossed by the ureters and the spermatic vessels, besides which, the left common il- 
 iac is crossed by the inferior mesenteric artery ; they are surrounded by a great number 
 of lymphatic glands, and rest above upon the vertebral column, and on the outside and 
 below upon the inner side of the psoas muscle. 
 
 It is of great importance to comprehend their relations with the common iliac veins. 
 The veins are situated behind the arteries ; but as the right and left vein unite on the 
 right side of the vertebral column, the left common iliac vein comes into relation with 
 both common iliac arteries. 
 
 The common iliac artery gives off no collateral branch ; it merely supplies some twigs 
 to the cellular tissue, the lymphatic glands, and the coats of the common iliac veins. It 
 occasionally gives off one of the renal arteries ; and it has been seen to supply the sper- 
 matic and the ilio-lumbar arteries. 
 
 Terminal Branches. — The common iliac artery terminates by dividing into two branch- 
 es, which remain in contact with each other for a short distance : the internal branch 
 dips into the pelvis, and is called the internal iliac or hypogastric artery ; tlie external 
 branch continues in the original course of the common iliac, and is termed the external 
 iliac artery. 
 
 Thk Internal Iliac or Hypogastric Artery. 
 
 The internal iliac or hypogastric artery {t,figs. 199, 212) is distributed to all the organs 
 contained in the cavity of the pelvis ; to the muscles pig, 212. 
 
 which line it within and cover it without ; to the exter- 
 nal and internal organs of generation, and to the integ- 
 uments. 
 
 It passes at first obliquely downward and forward, 
 and, as it were, in contact with the external iliac ; it 
 then dips vertically into the pelvis in front of the sacro- 
 iliac synchondrosis, describing a short curve ; and, after 
 a course of about one inch or one inch and a half in length, 
 divides opposite the upper part of the sacro-sciatic notch 
 into a greater or less number of branches, which do not 
 always arise in the same way from the principal trunk, 
 but whose ultimate distribution is constant. It is cov- 
 ered by peritoneum, and is crossed by the ureter ; it rests 
 behind on the lumbo-sacral nerve and pyriformis muscle*; 
 and the internal iliac vein is behind and to its outer side. 
 
 Its branches, all of which sometimes arise from two 
 principal trunks, one anterior and the other posterior, may be divided into an antenar 
 set, consisting of the umbilical, vesical, obturator, middle hemorrhoidal, uterine, vaginal, aei- 
 atic, and internal pudic arteries ; and a posterior set, including the ilio-lumbar, lateral, *a- 
 cral, and gluteal arteries. Altogether, there are nine in the male and eleven in the female. 
 
 The Umbilical Artery. 
 
 The umbilical artery, which is so large in the foetus, is converted into an impermeable 
 cord {xt;fig. 212) in the adult, excepting near its origin {a), where it gives off some ves- 
 ical branches : the examination of the umbilical arteries belongs, therefore, more espe- 
 cially to the anatomy of the foetus. They are intended to convey the blood of the foetus 
 to the placenta, and are then the continuations of the common iliac arteries. The ex- 
 ternal and internal iliacs, being very small at that period, in correspondence with the 
 small size of the abdominal extremities, appear to be nothing more than divisions of the 
 umbilical. 
 
 The umbilical arteries pass downward, forward, and outward, and, having arrived at 
 the sides of the bladder, run along them, in order to reach the umbilical ring, through 
 which they emerge from the abdomen, and, having traversed the whole length of the 
 umbilical cord in a spiral and tortuous manner, are at length distributed to the placenta.* 
 
 The vesical, middle hemorrhoil.il, uterine, vaginal, and obturator arteries are given 
 off in succession from the apparently ligamentous cord formed by the umbilical artery 
 near its origin. 
 
 The Vesical Arteries. 
 These are variable in number : the principal of them on each side are given off from 
 
 * It is curious to study the variable manner in which the umbilical arteries are converted, after Ijirth, into 
 a fibrous tissue. Sometimes these arteries are converted into two regular cords, which converge towards the 
 umbilicus. At other times each of these cords is subdivided into irregular bundles which it is difficult to 
 trace to their true origin. 
 
 4A 
 
654 ANGEIOLOGY. 
 
 the umbilical artery (a), which seems to be converted into a ligamentous cord (u) at the 
 place where the vesical arteries arise, but which is in reality pervious. This ligament- 
 ous appearance of the umbilical arteries depends upon the narrowness of their canal, as 
 compared with the thickness of their coats. Other vesical branches arise from the mid- 
 dle hemorrhoidal and obturator arteries, and in the female from the uterine and vaginal. 
 We shall divide the vesical arteries into the posterior, the anterior, and the inferior. 
 
 The posterier vesical artery {b,fig. 212) frequently arises, in the female, by a common 
 trunk with the uterine. It reaches the base of the bladder, on the outer side of the ure- 
 ter, passes inward and upward upon the posterior surface, as far even as the summit of 
 that viscus. I have seen the right posterior vesical artery, of large size, running along 
 the posterior surface of the bladder in the median line, and prolonged upon the urachus ; 
 the left posterior vesical was very small, and, in fact, rudimentary. 
 
 The anterior vesical (c) arises from the umbilical, from the obturator, and sometimes 
 from the internal pudic artery. When it arises from the umbilical, it is given off from 
 that artery opposite the sides of the bladder, and passes downward and inward along its 
 anterior surface. I have seen it given off near the summit of that organ. When it ari- 
 ses from the obturator or the internal pudic, it traverses the anterior lig2iment of the blad- 
 der, and passes upward upon the front of that organ. 
 
 I have seen a very large vesical artery given off from the obturator, which, in that 
 case, arose from the epigastric, and farther the vesical artery arose by a common trunk 
 with the artery of the corpus cavernosum. 
 
 The inferior vesical {d), which often arises direct from the internal iliac, reaches the 
 inferior fundus of the bladder, and ramifies abundantly upon it and the commencement 
 of the urethra : in the male it also supplies the corresponding vesicula seminalis and vas 
 deferens, the branch to which is called the deferential artery, and the prostatic portion 
 of the urethra. I have seen the dorsal artery of the penis arise from the inferior vesical. 
 
 The Middle Hemorrhoidal Artery. 
 This is a small artery (e), which is sometimes wanting, its place being then supplied 
 by branches from different sources, but especially from the sciatic or the internal pudic ; 
 it passes upon the sides of the anterior surface of the rectum, where it terminates by 
 anastomosing with the superior and inferior hemorrhoidal arteries. 
 
 The Uterine Artery. 
 
 The uterine artery {n n,jig. 198) arises from the umbilica., near the posterior vesical, 
 and frequently by a common trunk with it ; passes transversely inward to the corre- 
 sponding lateral border of the uterus, a little above the os tincae ; is reflected upward 
 along the uterus, and terminates by expanding into several ascending branches, of which 
 the anterior reach the front, the posterior the back, and the middle the upper border of 
 the viscus, and inosculate either with their fellows of the opposite side, or with the uter- 
 ine branches of the ovarian artery. The uterine arteries are remarkable for the great 
 size which they acquire during pregnancy, and also for their tortuous and spiral course, 
 even to their smallest branches : a disposition which no other artery presents in the 
 same degree. These tortuosities, instead of diminishing, appear to increase during 
 pregnancy : a fact which seems opposed to the view generally adopted regarding the 
 use of arterial flexuosities in organs liable to variations in their size. 
 
 Collateral Branches. — At the point of its reflection, each uterine artery gives off one or 
 more descending branches between the vagina and the bladder to supply both parts ; in 
 their course along the borders of the uterus, they furnish a series of anterior and poste- 
 rior ascending branches, which are distributed in the same way as the terminal ascending 
 branches ; they all anastomose in the median line with their fellows of the opposite side. 
 
 Relations. — The trunks of the uterine arteries are beneath the peritoneum ; the prin- 
 cipal branches are situated under a thin layer of the substance of the uterus, and the ul- 
 timate divisions and subdivisions enter its tissue. 
 
 The Vaginal Artery. 
 The vaginal artery arises from the umbilical, sometimes before, sometimes after the 
 origin of the uterine, which is sometimes given off from a conunon trunk with it. It is 
 as large as the uterine in young subjects, but is smaller than it after puberty. It de- 
 scends directly upon the sides of the vagina, to which it gives off a numerous series of 
 branches, supplies a considerable branch to the neck of the bladder and the urethra, 
 gives an equally large one to the bulb of the vagina, and then passes backward between 
 the orifice of the vagina and the rectum, and anastomoses with its fellow of the oppo- 
 site side. 
 
 The Obturator Artery. 
 The obturator artery {f,fig. 212) is remarkable for the varieties of its origin, and for 
 the important consequences which result from those varieties, in reference to the oper- 
 ation for femoral hernia. 
 
THE ILIO-LUMBAR ARTERY. SS5 
 
 It generally arises from the internal iliac by the side of the umbilical, but sometimes 
 above the gluteal ; it is almost as frequently given off from the external iliac, either di- 
 rectly,* which is rare, or by a common trunk with the epigastric. Lastly, and much 
 - more rarely, it arises from the femoral artery. 
 
 The course of the obturator artery is modified by these differences of origin, which, 
 notwithstanding the assertion of some anatomists, are as common in the male as the fe- 
 male, and which may occur on one side only, or on both sides of the same subject. 
 Thus, when the obturator comes from the femoral, it passes upward on the inner side 
 of the femoral vein, enters the pelvis through the crural ring, is reflected upon the upper 
 surface of the body of the os pubis, then passes behind it and gains the internal opening 
 of the sub-pubic canal. When it arises by a common trunk with the epigastric, it dips 
 vertically behind the os pubis to the same opening. In its ordinary mode of origin, it 
 passes horizontally forward upon the sides of the brim of the pelvis, being bound down 
 by the peritoneum, runs parallel with the obturator nerve (n), which is placed above i 
 gains with it the internal orifice of the sub-pubic canal, and, having traversed this pas- 
 sage, divides into an internal and an external terminal branch. 
 
 Collateral Branches. — Near its origin, the obturator artery gives off a tolerably large 
 branch, the iliac, which perforates the iliac fascia, dips between the iliacus muscle and 
 the ihac fossa, and anastomoses with a branch of the circumflex iliac artery, t 
 
 As it enters the sub-pubic canal it gives off a small branch, which passes transversely 
 behind the body of the pubis, and ramifies upon the side of the symphysis, anastomo- 
 sing with its fellow of the opposite side ; also a small ascending branch (s), which anas- 
 tomoses with the epigastric artery, and which may be regarded, according to Meckel, as 
 one of the origins of the obturator ; so that the variety in which the obturator arises 
 from the epigastric is often nothing more than an unusual development of this commu- 
 nicating branch. In support of this view, we may quote the very rare case, in which 
 the obturator arises by two roots of almost equal size, one coming from the epigastric, 
 and the other from the interned iliac. 
 
 Terminal Branches. — The interned branch passes between the obturator extemus mus- 
 cle and the conjoined rami of the pubes and ischium, so as to describe a semicircle 
 around the inner half of the obturator foramen, gives branches to the periosteum of the 
 OS pubis, muscular branches to the two obturator and to the adductor muscles, some 
 genital branches to the coverings of the testis in the male and to the labia majora in 
 the female, and, lastly, some very important anastomotic branches, which join those of 
 the internal circumflex. 
 
 The external branch runs along the outer half of the obturator foramen ; it is placed, 
 like the preceding, between the two obturator muscles, and terminates between the 
 neck of the femur and the quadratus femoris muscle by anastomosing with the sciatic 
 artery. This anastomosis is very remarkable. During its course, the external branch 
 supplies the obturator muscles and the hip-joint ; the articular branch enters by the 
 notch of the cotyloid cavity, and is lost in the reddish, fatty tissue situated at the bottom 
 of it. The distribution of the obturator artery is much more limited than that of the ob- 
 turator nerve. 
 
 The Ilio-lumbar Artery. 
 
 The ilio-lumbar artery (A) arises from the back of the internal iliac, and, tolerably fre- 
 quently, from the gluteal. There are often two ilio-lumbar arteries. This vessel bears 
 the same relation to the lumbar arteries that the superior intercostal does to the aortic 
 intercostals ; its size and distribution vary according to the presence or absence of the 
 fifth lumbar artery. 
 
 It has a retrograde course, running upward and backward in front of the lumbo-sacral 
 nerve, and behind the psoas muscle, and soon divides into two branches : an ascending 
 or lumbar, and a transverse or iliac. The ascending or lumbar branch passes vertically 
 upward along the bodies of the lumbar vertebrae, hidden by the psoas, and subdivides 
 into a muscular branch, which corresponds to the abdominal branches of the lumbar ar- 
 teries, and is distributed to the psoas and to the quadratus lumborum ; and a spinal 
 branch, which enters the vertebral canal by the foramen between the fifth lumbar verte- 
 bra and the sacrum, and is distributed in the same manner £is the other spinal arteries. 
 
 * The cases where th*' obturator artery arises separately from the external iliac are not unfrequeut. The 
 following description may serve as an example. In one case, the obturator artery arose separately from the 
 external iliac artery, at the distance of one inch above the femoral arch, and above the origin of the epigastric 
 artery ; it went downward and inward to reach the lateral wall of the pelvis, crossed the obturator nerve, and 
 entered the sub-pubic canal. In this subject, the obturator vein joined also the external iliac vein. The same 
 disposition existed on both sides. 
 
 t The obturator artery sometimes gives off the artery to the bulb of the urethra. In a preparation which 
 was exhibited by M. Dcnonvilliers, now chef des travaux anatomiques, at the concours for the office of prosec- 
 tor, I have seen a voluminous branch whicli had arisen from the obturator artery, extending all along the in- 
 ternal part of the obturator foramen, cross perpendicularly the posterior surface of the descending branch of 
 the pubis, reach the bulb transversely by crossing the internal pudic artery, above which it was placed. This 
 was on the left side. On the right side the arrangement was normal. This arrangement is not as rare as 
 might be believed : it is evident that the ligature of ihe internal pudic artery would be useless in a case of 
 this kind, in arresting a hemorrhage consequent upon nii operation for the stone. 
 
ANGEIOLOGT. 
 
 The transverse or iliac branch passes horizontally outward, opposite the brim of the 
 pelvis, and divides into a superficial branch, which passes under the iliac fascia, ramifies 
 upon the iliacus muscle, and anastomoses with the circumflex iliac artery ; and into a 
 deep and much larger branch, which passes between the ihacus muscle and the ihac 
 fossa, and divides into muscular and periosteal twigs. The principal nutritious artery 
 of the ilium is derived from this branch. 
 
 When there are two ilio-lumbar arteries, the superior represents the lumbar branch, 
 and the inferior the iliac branch : in such a case the latter branch always arises from the 
 gluteal artery. 
 
 The Lateral Sacral Arteries. 
 
 Most'commonly there are two lateral sacral arteries on each side ; they belong rather 
 to the interior of the sacral canal than to the cavity of the pelvis, and form a continuation 
 of the spinal branches of the lumbar arteries ; they almost as frequently arise from the 
 gluteal as from the internal iliac ; sometimes they are derived from the sciatic or the 
 Sio-lumbar arteries. 
 
 The superior lateral sacral is generally of considerable size. It passes almost horizon- 
 tally inward, and after having given off some small transverse branches, which anasto- 
 mose with the middle sacral, enters the first anterior sacral foramen, and divides into 
 two branches : one intended for the nerves and their coverings, and another which emer- 
 ges from the sacral canal by the corresponding posterior sacral foramen, and is distribu- 
 ted to the spinal muscles and to the skin. 
 
 The inferior lateral sacral (Ji,fig. 212) is situated at first under the digitations of the 
 pyriformis muscle, afterward passes in front of that muscle, and is directed inward and 
 downward on the inner side of the sacral foramina, and along the borders of the coccyx, 
 where it anastomoses with the middle sacral. In this course it gives off a series of very 
 small internal branches, which correspond to the several sacral vertebrae, and anastomose 
 with the middle sacral ; also some posterior or spinal branches, each of which enters the 
 sacral canal through the corresponding sacral foramen, and subdivides into two small 
 branches : one intended for the nerves and their coverings, while the other emerges from 
 the sacral canal by the corresponding posterior sacral foramen, and is distributed to the 
 muscles and the skin. "When the superior lateral sacral is small, the posterior or spinal 
 branch of the inferior lateral sacral is very large. The inferior lateral sacral artery often 
 terminates by a spinal branch, which enters at the lowest anterior sacral foramen. 
 
 The Gluteal Artery. 
 
 The gluteal artery (rn,fig. 212), called also the posterior iliac, is the largest branch of 
 the internal iliac, of which it might be considered the continuation. It might be called 
 superior gluteal, in contradistinction to the sciatic, which is, in reality, an inferior gluteal. 
 It passes downward and backward between the lumbosacral nerve and the first sacral 
 nerve, escapes from the pelvis at the upper part of the great sacro-sciatic notch, above 
 the pyriformis muscle {m,fig. 45), is reflected upon the border of that notch, and divides 
 into a superficial and a deep branch. The superficial branch (a) passes horizontally for- 
 ward, between the glutaeus maximus and medius, and is almost entirely distributed to the 
 upper part of the first-named muscle and to the adjacent part of the skin ; the deep branch 
 {b) passes between the glutaeus medius and minimus, and subdivides into two branches ; 
 the lower of these runs horizontally, and may be traced as far as the anterior border of 
 the glutaeus medius, while the other very nearly follows the curve described by the origin 
 of the glutaeus minimus. This branch gives off some muscular arteries, several nutri- 
 tious arteries to the bone, and severtd articular branches. 
 
 One circumstance regarding the gluteal artery worthy of remark is the fact that, in 
 common with all arteries of a certain size, it is liable to aneurism, and that for the cure 
 of this aneurism (which has always been the result of external violence), the common 
 iliac artery has in two cases been tied in America, and the gluteal artery itself recently 
 by an English surgeon. 
 
 The Sciatic Artery. 
 The sciatic artery (o, fig. 212), from its distribution, might be called the inferior gluteal. 
 It often arises by a common trunk, either with the gluteal or with the internal pudic, be- 
 hind and internal to which it is situated ; it descends in front of the sacral plexus and the 
 pyriformis muscle, traverses the sacral plexus, emerges from the pelvis (o, fig. 215) be- 
 tween the pyriformis and the lesser sacro-sciatic ligament, accompanied on its inner side 
 by the great sciatic nerve, and behind by the internal pudic artery (p). Outside the pel- 
 vis, the sciatic artery gives off iniernal or transverse branches, some of which pass trans- 
 versely inward between the gluteus maximus and the great sacro-sciatic ligament, while 
 others (c) perforate that ligament, and ramify in the internal attachments of the glutaeus 
 maximus. Several of these branches ramify upon the skin of the coccygeal region ; its 
 other branches are descending, the largest of which {d) gains the deep surface of the 
 glutaeus maximus, and enters that muscle by numerous branches, which become cuta- 
 
INTERNAL PUDIC ARTERY. 
 
 657 
 
 Fig. 213. 
 
 neous at their termination ; one and often two or three branches (c) of the sciatic artery 
 attach themselves to the deep surface of the great sciatic nerve, and accompany it to the 
 lower part of the thigh. A great number of twigs are given off from the several branches 
 of the sciatic artery, which are distributed to the small rotator muscles, or to the origins 
 of the muscles attached to the tuberosity of the ischium, while others anastomose with 
 the circumflex (/) and perforating arteries («) derived from the femoral. Among these 
 anastomoses, I would point out one very considerable anastomotic loop, formed behind 
 the neck of the femur by the sciatic and internal circumflex arteries, and constituting one 
 of the principal communications between the internal iliac and femoral arteries. 
 
 The hitemal Pudic Artery. 
 
 The internal pudic (jp,fig. 212), the terminal branch of the internal iliac, is, practically 
 speaking, the most important of all the pelvic arteries. It is smaller than the sciatic, 
 from which it is sometimes given off, either shortly after the origin of that vessel, or as 
 it is passing out from the pelvis. The internal pudic runs in a tortuous manner down- 
 ward, in front of the sacral plexus and the pyriformis muscle, parallel to the sciatic ar- 
 tery (o), which is behind it ; escapes from the pelvis, together with that vessel {p, o,fig. 
 215), between the pyriformis muscle and the spine of the ischium ; is reflected upon 
 that process, turning round it from behind forward, so as to embrace in succession its 
 posterior, its external, and its anterior surfaces, and then enters the pelvis again between 
 the two sacro-sciatic ligaments. The artery, af- 
 ter descending a short distance, then becomes as- 
 cending, and is situated in the ischio-rectal fossa 
 {a, Jig. 213), and is applied to the internal surface 
 of the tuberosity of the ischium, or, rather, of the 
 obturator internus muscle, with which it is kept 
 in contact by a layer of fascia : it is separated 
 from the levator ani by a considerable quantity of 
 fat, and having reached the posterior border of ^ 
 the transversus perinei muscle, it divides into an 
 inferior, superficial, or perineal branch (c), and a 
 stiperior or deep branch (e), w^hich is distributed to 
 the penis in the male and to the clitoris in the fe- 
 male. An important variety in the course of this 
 artery has been pointed out by Bums, who, in a 
 male subject, saw the trunk of the internal pudic, instead of passing out of the pelvis, run 
 upon the sides of the inferior fundus of the bladder, perforate the upper part of the pros- 
 tate, and then terminate in the usual manner. 
 
 Collateral Branches. — During its course within the pelvis, the internal pudic supplies 
 branches to the bladder, rectum, vesiculae seminales, and prostate in the male, and to 
 the vagina in the female ; it also rather frequently gives off the middle hemorrhoidal. 
 As it turns round the spine of the ischium, it gives some branches to the rotator mus- 
 cles of the thigh. Opposite the internal surface of the tuberosity of the ischium, it gives 
 origin to one or more branches, named the external or inferior hemorrhoidal (b,jig. 213), 
 which run inward to be distributed to the lower end of the rectum, to the sphincter, 
 the levator ani, and the skin ; also some branches which proceed outward, some to sup- 
 ply the periosteum of the tuberosity, while others ramify in the muscles attached to that 
 process ; lastly, a very important communicating branch passes between the tuberosity 
 of the ischium and the great trochanter, and anastomoses with the sciatic and internal 
 circumflex arteries. 
 
 Terminal branches. — These differ in the two sexes. We shall first describe them in 
 the male : 
 
 The inferior branch, the superficial artery of the perineum, or the perineal artery (c), is 
 smaller than the superior branch : it passes forward and inward, in the cellular interval 
 between the ischio-cavernosus and the bulbo-cavernosus ; above, i. e., deeper than the 
 superficial fascia of the perineum, which separates it from the skin ; and below, i. e., 
 superficial to the transversus perinei muscle, it thus reaches the dartos at the side of the 
 median line, where it is named the artery of the septum, and is distributed to the scrotum 
 and the skin of the penis. 
 
 During its course the superficial perineal artery gives internal and external branches. 
 Some of the internal branches run along the posterior border of the transversus perinei 
 muscle, and are sometimes so large as to bleed very profusely when they are divided in 
 the operation of lithotomy ; from its situation, one of them is named the transverse ar- 
 tery of the perineum (d). 
 
 The deep superior or deep branch (e), or the artery of the penis (in the male), is the con- 
 tinuation of the trunk of the internal pudic, both in regard to size and direction : it runs 
 along the ascending ramus of the ischium, between the layers of the triangular ligament ; 
 above, i. e., deeper than the transverse muscle, which it sometimes perforates, also above 
 the ischio-cavernosus and the corresponding crus of the corpus cavernosum ; and oppo- 
 
ANGEIOLOGY. 
 
 site the point at which the two crura unite, it subdivides into two branches, viz., the 
 dorsal artery of the penis (g) and the artery of the corpus cavernosum Qi). 
 
 During its course, the artery of the penis gives off a very important collateral branch, 
 named the artery of the bulb (/), which is as large as the superficial perineal artery, is 
 sometimes double, and generally arises near the bulb, passes transversely inward, above 
 the middle perineal fascia or triangular ligament, or, rather, in the substance of that 
 ligament, and is distributed to the bulb of the urethra and to the spongy portion of this 
 canal.* 
 
 The dorsal artery of the penis (g) is sometimes the only terminal branch of the internal 
 pudic, and then a very delicate twig supplies the place of the artery of the corpus cav- 
 ernosum, which, in this case, is supplied from another source. This artery reaches the 
 dorsal surface of the penis by passing between the symphysis pubis and the crura of the 
 corpus cavernosum, and perforating the suspensory ligament of the penis, and then runs 
 in a very tortuous manner along, beneath the skin, upon the dorsal aspect of that organ, 
 on one side of the median line, being retained in its position by a layer of fibrous mem- 
 brane : it terminates by ramifying in the prepuce and in the glans, around the base of 
 which it forms a corona. I have seen the dorsal artery of the penis given off by one of 
 the external pubic arteries, from which it arose immediately above the entrance of the 
 saphenous vein into the femoral ; it then formed a curve in the groin, with its concav- 
 ity directed downward, and passed upon the sides of the dorsal surface of the penis ; in 
 another instance, the dorsal artery of the penis was derived from the obturator, or, rath- 
 er, it had two roots : a very small one, which had the usual origin, and a large one, 
 which arose from the obturator and passed under the symphysis. The right and left 
 dorsal arteries of the penis sometimes anastomose by a transverse branch, like the an- 
 terior cerebral arteries. 
 
 The artery of the corpus cavernosum (h) is also sometimes the only terminal branch of 
 the internal pudic artery, the dorsal artery of the penis, in such cases, being derived from 
 some other source. I have seen the cavernous artery arise from the obturator. In all 
 cases it enters the corpus cavernosum by the corresponding crus, runs along its median 
 septum, and ramifies in its areolar structure. 
 
 I have seen the dorsal arteries of the penis and the cavernous artery arise by a com- 
 mon trunk from the hypogastric ; this trunk passed directly from behind forward to be 
 divided immediately. The same disposition existed on both sides. The internal pudic 
 artery gave off a small cavernous artery. 
 
 In the female, the terminal branches of the internal pudic are arranged as follows : 
 the inferior or superficial perineal branch is larger than the superior, and might be named 
 the artery of the labia majora, to which it is distributed ; the superior or deep branch, or the 
 artery of the clitoris, runs along in contact with the tuberosity of the ischium, and then 
 with its ascending ramus, and having given off a branch, which runs inward to the bulb 
 of the vagina, terminates in the dorsal artery and cavernous artery of the clitoris, these ves- 
 sels being very small in consequence of the diminutive size of that organ. 
 
 Summary of the Distribution of the Internal Iliac Jlrtery. 
 
 The internal iliac artery, which is so deeply situated as to be inaccessible to the sur- 
 geon, sends branches to all the organs contained in the cavity of the pelvis ; to the bony 
 parietes of the pelvis and the sacral canal ; to the muscles which line the pelvis within 
 and cover it without ; and to the skin and the external genital organs. 
 
 Its several branches may be divided into parietal and visceral. The visceral branches 
 are the vesical, middle hemorrhoidal, vaginal, and uterine arteries, and the deep branch 
 of the internal pudic. The sympathy existing between all the organs to which the above- 
 named vessels are distributed, depends less upon those vessels having a common source 
 than upon the community of origin of the several nerves which those vessels serve to 
 support. 
 
 The parietal branches are the ilio-lumbar and lateral sacral arteries, which, with the^ 
 middle sacral, continue the series of intercostal and lumbar arteries into the sacral re-* 
 gion, and supply the sacrum, the spinal nerves and their coverings, and also the muscles 
 of the vertebral grooves and the skin of the sacral region ; the glutaeal and the sciatic ar- 
 teries intended for the muscles of the glutaeal region ; the superficial branch of the internal 
 pudic artery, which supplies the perineum ; and, lastly, the obturator artery, which forms 
 an arterial circle around the obturator foramen, and supplies the obturator muscles. 
 
 Several branches of the internal iliac artery establish anastomoses between that ves- 
 sel and the femoral artery ; these are more especially the sciatic, the internal pudic, the 
 gluteal, and the obturator arteries. 
 
 Artery of the Lower Extremity, or Crural Trunk. 
 The arterial trunk of the lower extremity, or the crural trunk (Chaussier), corresponds 
 
 * The artery of the bulb, after having traversed the bulb, is directed from behind forward in the substance 
 of the spongy portion of the urethra, and may be followed up to about its middle part. When the artery of ths 
 bulb comes from the obturator artery, the inferior pudic sends a rudimentary branch to the bulb. It is the 
 pudic artery which supplies Cowper's glands. 
 
THE EXTERNAL ILIAC ARTERY. 559 
 
 With the brachial trunk of the upper extremity. This vessel, which is the direct con- 
 tinuation of the common iliac artery, passes downward and outward, emerges from the 
 pelvis beneath the crural arch, and thus reaches the anterior region of the thigh. Op- 
 posite the junction of the two upper thirds with the lower third of the femur, it traverses 
 the fibrous canal formed for it by the tendon of the great adductor muscle, and thus 
 gains the popliteal space, at the lower part of which it terminates by dividing into two 
 branches. The numerous and important relations of this vessel, and the great number 
 of branches arising from it, have led to its division by anatomists into three portions, 
 which are named the external iliac artery, the femoral or crural artery, and the popliteal ar- 
 tery. The two terminal branches are the anterior tibial, which, in the foot, is termed the 
 dorsal artery of the foot, and the tibio-peroneal trunk, which divides into the peroneal and 
 posterior tibial arteries, the latter of which terminates in the sole of the foot by subdivi- 
 ding into the internal and external plantar arteries. 
 
 The External Iliac Arteky. 
 
 The external iliac artery (r, figs. 199, 212), the outer of the two branches into which the 
 common iliac divides, is analogous to the subclavian artery in the upper extremity. It 
 extends from the highest part of the sacro-iliac symphysis to the lower border of the fem- 
 oral arch or Poupart's ligament, below which it takes the name of femoral artery. It is 
 directed obliquely downward and outward, in a line extending from the sacro-iliac sym- 
 physis to the crural ring, and is almost always straight, but sometimes tortuous. It has 
 the following relations : in front and on the inner side, it is covered by the peritoneum, 
 which is very loosely attached to it : an important fact, which enables the surgeon to 
 separate that membrane from it in applying a ligature to the vessel ; on the outer side, it 
 rests against the psoas muscle, from which it is separated by the iUac fascia ; behind, the 
 artery of the right side is in relation with the corresponding external iliac vein, which 
 is placed to its inner side below ; on the left side the vein is below, and on the inner side 
 of the artery ; lastly, the genito-crural nerve, just as it is about to enter the inguinal ca- 
 nal, crosses in front of this artery, and so also do the spermatic vessels ; the circumflex 
 iliac vein crosses it at right angles behind the femoral arch, in order to terminate in the 
 external iliac vein ; besides this, it is covered immediately behind the arch by several 
 lymphatic glands ; higher up, the ureter crosses obliquely in front of it, and the artery of 
 the right side is covered by the termination of the ileum, and that of the left side by the 
 sigmoid flexure of the colon. 
 
 Collateral Branches. — The external iliac artery furnishes no branches, excepting at its 
 lower part, near the femoral arch, where it gives off the epigastric and circumflex iliac 
 arteries. 
 
 The Epigastric Artery. 
 
 The epigastric artery is, practically speaking, one of the most important to be well un- 
 derstood, on account of its relations with the crural ring and inguinal canal, that is to 
 say, with the parts through which the viscera generally descend in herniae. 
 
 This artery (v,figs. 199, 212) arises from the inner side of the external iliac, two or 
 three lines above the femoral arch. Its origin, however, is subject to some varieties : 
 sometimes it takes place half an inch, one, or even two inches above the crural arch : an 
 important fact in reference to the application of a ligature to the external iliac. Hessel- 
 bach and several others state that they have seen the epigastric arise from the obtura- 
 tor artery ; but their descriptions appear to me to prove nothing more than that the epi- 
 gastric and obturator arteries may arise by a common trunk. It is worthy of remark 
 that the obturator is often observed to arise from the epigastric, while there is, perhaps, 
 no example of the epigastric being derived from the obturator. The obturator so fre- 
 quently arises by a common trunk with the epigastric,* that many anatomists have 
 thought that the obturator is derived from the epigastric more frequently than from the 
 internal iUac artery. In 250 subjects examined for this purpose by M. Jules Cloquet, 
 the obturator arose 150 times from the epigastric on both sides, 28 times on one side 
 only, and 6 times from the femoral artery. Althoug:h it is a very common occurrence to 
 have the obturator artery arising from the epigastric, it is very rare to find the epigas- 
 tric taking its origin from the obturator. This anatomical variety has only been report- 
 ed as having occurred in two cases. One can easily understand how dangerous it would 
 be to operate for the relief of a strangulated hernia in such a case. 
 
 The epigastric artery, whether it gives off the obturator or not, passes transversely 
 or obliquely inward, and, having arrived below the spermatic cord in the male, and the 
 round ligament in the female, is reflected upward, so as to describe a curve having its 
 concavity directed upward, and corresponding to the loop formed by the spermatic cord 
 o' round ligament, the concavity of which is directed downward. When the cbturator 
 arises by a common trunk with the epigastric, it is given oflf at the point where the lat- 
 ter is reflected upward, and from the convexity of the curve. After being reflected, the 
 
 * It would be very difficult to explain why the epigastric and the obturator arteries are so intimately cott 
 nected at their origins. 
 
9Bfk ANGEI0L06Y. 
 
 epigastric artery ascends obliquely inward, soon reaches the outer border, and next the 
 posterior surface of the rectus abdominis muscle, and then passes vertically upward. 
 Having reached the umbilicus, it penetrates into the substance of the rectus, and termi- 
 nates by anastomosing with the internal mammary artery. 
 
 Relations. — The relations of the transverse, oblique, and vertical portions of the epi- 
 gastric artery should be examined separately. The transverse portion varies in length 
 in different subjects ; sometimes it is almost entirely wanting, the artery running im- 
 mediately upward ; at other times it is an inch and a half in length. This difference in 
 length, which is of no consequence when the obturator artery arises from the internal 
 iliac, becomes highly important when that vessel is given off from the epigastric* 
 
 This transverse portion of the artery is directed obliquely downward, when the ej - 
 gastric arises at a certain distance above the ring. 
 
 The oblique portion of the epigastric artery forms the outer side of a triangle, the in- 
 ner side of which is formed by the outer border of the rectus abdominis muscle, and the 
 base by the crural arch : the epigastric constitutes the true boundary between the inter- 
 nal inguinal fossa, which comprises all the triangular space situated on the inner side 
 of the vessel, and the external inguinal fossa, which comprises the space upon its outer 
 side. The abdominal orifice of the inguinal canal is situated in the external inguinal 
 fossa, and, consequently, to the outer side of the epigastric artery. Those inguinal her- 
 nise which pass through the internal fossa are called internal or direct inguinal herniae ; 
 those which take place on the outer side of the artery are called external or oblique in- 
 guinal. 
 
 In its horizontal and oblique portions, the epigastric artery is placed between the per- 
 itoneum and the fascia transversalis. I should observe that the spermatic cord in the 
 male, and the round ligament in the female, do not cross the epigastric artery precisely 
 in the situation of the loop which this vessel describes, but a little above it. The axis 
 of the inguinal canal being directed obliquely downward and inward, intersects at right 
 angles the oblique portion of the artery, which slopes in the opposite direction. 
 
 In its vertical portion, the epigastric artery is situated between the rectus and the pos- 
 terior wall of the sheath of that muscle until near the umbilicus, where it dips into the 
 fleshy fibres. 
 
 Collateral Branches. — Near its origin, or, rather, opposite the bend which it takes, the 
 epigastric artery sometimes gives off the internal circumflex, which, as we shall here- 
 after see, generally arises from the deep femoral. It always gives off the following 
 branches : a cremasteric branch {I, Jig- 214), which enters the inguinal canal, runs along 
 the fibrous sheath of the cord in the male, and the round ligament in the female, and 
 passes in the one to the coverings of the testicles, and in the other to the labia majora ; 
 a second branch, which runs along the inner portion of the femoral arch, and anasto- 
 moses with its fellow of the opposite side behind the symphysis ; and, lastly, a branch 
 which crosses the horizontal ramus of the pubes at right angles, and anastomoses with 
 the obturator. I have already stated that this small branch may be regarded as forming 
 the trunk of the obturator when that artery arises from the epigastric. In its oblique 
 and vertical portions, the epigastric gives off a number of internal and external ascending 
 branches, which pass very obliquely through the rectus abdominis, partially supply that 
 muscle, and then pierce the anterior wall of its sheath, the internal branches near the 
 linea alba, and the external branches near the outer border of the sheath, to ramify upon 
 the skin. These branches anastomose with the internal mammary and with the lumbar 
 arteries. 
 
 The anastomosis of the epigastric with the internal mammary takes place only in the 
 substance of the rectus, and by very small vessels. 
 
 The Circumflex Iliac Artery. 
 
 The circumflex or posterior iliac artery {x, figs. 199, 212), smaller than the epigastric, 
 arises from the outer part of the external iliac, either opposite the epigastric or a little 
 below it. It sometimes arises from the upper part of the femoral artery : it is generally 
 single, but occasionally double, which may be regarded as resulting from a premature 
 division of the vessel. 
 
 It passes obUquely upward and outward, behind the crural arch, with which it is held 
 in contact by a fibrous layer interposed between it and the peritoneum. Opposite the 
 anterior superior spinous process of the ihum it divides into two branches : one is an 
 ascending or abdominal branch, which passes upward, in the substance of the abdominal 
 parietes, between the transversalis and obUquus intemus muscles, parallel with the ep- 
 igastric artery, and terminates by anastomosing with the inferior intercostal and the 
 lumbar arteries ; the other is the circumflex ihac artery properly so called, which is the 
 
 * [If the obturator arises high up from the epigastric, it describes, before it euters the pelvis, a semicircle 
 extending along the upper, and then the inner border of the crural ring ; and, consequently, has such rela- 
 tions with the neck of the sac in femoral hernia, that render it almost impossible to avoid wounding the ar- 
 tery in dividing the stricture upward and inward. But if, as is much more frequently the case, it arises from 
 near the commencement of the epigastric, or by a common trunk with it, it then descends at once into the pel 
 vis obliquely along the outer border of the crural ring, and will have the same relation with a femoral henua.J 
 
THE FEMORAL ARTERY. 
 
 56« 
 
 continuation of the vessel in direction and sometimes in size ; it runs along the crest 
 of the ilium, is at first sub-aponeurotic, or, rather, is contained between two layers of 
 fascia in the cellular interval separating the transversalis from the obliquus internus, 
 and terminates by anastomosing with the fourth lumbar artery upon the crest of the ilium. 
 During its course, the circumflex iliac artery gives off ascending branches, which ram- 
 ify in the muscles and integuments of the abdominal parietes ; and descending branches, 
 which ramify in the iliac fossa, and anastomose with the iliac branches of the obturator 
 artery. 
 
 The Femoral Artery. 
 
 The femoral or crurcu artery (a a', fig. 214) is that portion of the artery of the Icn'er ex- 
 tremity which intervenes between the external iliac and pop- Fig. 214. 
 liteal arteries ; it is bounded above by the crural arch, and 
 below by the junction of the two upper thirds with the lower 
 third of the thigh, or, rather, by the place where the artery 
 passes through the tendinous ring formed by the adductor 
 magnus. 
 
 It has been proposed to take as the lower boundary of the 
 femoral artery the origin of the deep femoral or profunda ar- 
 tery, which has been correctly regarded as a terminal branch 
 resulting from the bifurcation of the femoral artery, rather 
 than as a collateral branch. According to this view, which 
 has not been generally adopted, the femoral would not be more 
 than from an inch and a half to two inches in length, and 
 would divide into a superficial and deep femoral. 
 
 The femoral artery is directed vertically, and somewhat 
 obliquely backward, so that it forms a slight angle with the 
 external iliac, on account of the oblique inclination forward 
 of that vessel ; and, farther, although it is in front of the fe- 
 mur above, it is placed on the inner side of it below, prepara- 
 tory to becoming posterior to it in the popliteal space. A line 
 drawn from the middle of the space between the anterior su- 
 perior spinous process of the ilium and the symphysis pubis, 
 down to the inner side of the femur, below the middle of that 
 bone, would exactly represent its direction. The direction 
 of the femoral artery, in respect to the femur, is such, that 
 immediately below the femoral arch it is situated over the 
 point of junction of the inner with the two outer thirds of the 
 head of that bone, while lower down it is in relation with the 
 inner aspect of the bone ; the artery, therefore, forms an acute 
 angle, opening upward, with the shaft of the femur, and there 
 is an interval of an inch to eighteen lines between the vessel 
 and the upper part of the bone, into which instruments may 
 be passed without wounding the artery. Advantage is taken 
 of this fact in disarticulating the head of the femur in amputation at the hip-joint. 
 
 The femoral artery, which is slightly tortuous when the thigh is flexed upon the pelvis, 
 becomes straight when the limb is extended, and it is much stretched during forcible ex- 
 tension. 
 
 Relations. — In front, the femoral artery lies beneath the fascia in the triangular space 
 which is bounded on the inside by the inner border of the adductor longus ; on the out- 
 side, by the sartorius ; and above, by the femoral arch. Lower down, the sartorius is 
 placed between the fascia and the artery, which is in relation, first, with the inner bor- 
 der, then with the posterior surface, lastly, with the outer border of that muscle : besides 
 the fascia, a number of lymphatic glands lie between the upper part of the artery and 
 the skin. Enlargement of one or more of these glands has been mistaken for an aneu- 
 rism, and an aneurism for an enlarged gland. From these relations of the front of the 
 femoral artery, it foUoivs that its anterior aspect may be exposed in the whole of its ex- 
 tent, but that it is more superficial in the neighbourhood of the crural arch. 
 
 Behind, the femoral artery rests, first, upon the body of the pubes, or the ilio-pectineal 
 eminence, with which it is in immediate contact in emaciated subjects, but from which 
 it is generally separated by the contiguous borders of the psoas-iliac and the pectineus 
 muscles. The iliac fascia separates it from the psoas-iliac muscle, so that, in cases of 
 simple psoas abscess, or congestive abscess from caries of the lumbar vertebrae, the fem- 
 oral artery is situated in front of the sac of the abscess. The femoral artery is also in 
 relation, behind, with the head of the femur ; lower down, with the pectineus, and then 
 with the adductor longus. It follows, therefore, that the femoral artery may be very 
 eflfectually compressed at its upper part, since it is superficially situated, and rests upon 
 hard parts. 
 
 On Ike outer «ie, it is in relation, first, with the psoas-iliac, then with the inner border 
 
 4B 
 
562 ANGEIOLOGY. 
 
 of the sartorius, and, lastly, with the vastus internus, which separates it from the inner 
 surface of the femur. 
 
 In consequence of this relation to the bone, and also of the slight thickness of the sar- 
 torius, which separates it from the skin, the femoral artery may be compressed against 
 the femur from within outward in the middle third of the thigh. 
 
 On its inner side, it is in relation with the pectineus, the adductor longus, and afterward 
 with the outer border of the sartorius. 
 
 Relations of the Artery with the Vein and Nerves. — The femoral vein is situated on the 
 inner side of the artery above, but it soon passes behind it, and, still lower down, is on 
 its outer side. The crural nerve lies on the outer side of tlie artery, from which it is 
 separated by a fibrous layer belonging to the sheath of the psoas and iliaeus. The artery 
 and nerve, therefore, have no immediate relation with each other ; but the internal or 
 long saphenous nerve soon runs upon the sheath of the femoral vessels, and is situated 
 on the outside of the artery ; but as the vessel is passing through the tendon of the ad- 
 ductor magnus, the nerve leaves it, and, lower down, escapes from under the tendon of 
 the sartorius. The short saphenous nerve, or nerve of the internal vastus, is in relation 
 with the outer side of the artery for a short distance, and the vessel is also crossed by 
 another small nerve. 
 
 The Sheath of the Femoral Vessels. — ^The femoral artery and vein are enclosed in a proper 
 fibrous sheath, which is constructed, as it were, in the midst of the muscles of the thigh 
 (see Aponeurology). It is, therefore, necessary to open this sheath, and not that of 
 any of the surrounding muscles, in order to expose the artery. 
 
 Anatomical Varieties. — Independently of the very frequent and remarkable anatomical 
 varieties in the origin of the deep femoral artery, which is often given off opposite, and 
 sometimes above the femoral arch — varieties to which I shall immediately refer in speak- 
 ing of the deep femoral artery — ^the common femoral artery itself offers some varieties 
 which are not less interesting. The most important is the following, found in a prep- 
 aration deposited by M. Manec in the museum of Clamard : In this preparation, the fem- 
 oral artery presents behind the Fallopian ligament a caliber which is not larger than that 
 of the radial artery, and is lost in the anterior muscles of the thigh. The ischiatic ar- 
 tery, which is a branch of the hypogastric, presents, on the contrary, the caliber of the 
 femoral artery, descends backward along the great sciatic nerve, and is continuous with 
 the popliteal artery. During its course along the thigh, the ischiatic artery gives off the 
 muscular branches which generally come from the deep femoral artery. 
 
 Collateral Branches. — The collateral branches of the femoral are, the superficial epigas- 
 tric artery, the two external pudic arteries, a great number of muscular branches, and the 
 deep femoral artery. 
 
 The Superficial Epigastric Artery. 
 The superficial epigastric or sub-cutaneous abdominal artery (cut across at b,fig. 214) 
 is a very small, but remarkably constant branch, which arises from the front of the 
 femoral, and sometimes from the external pudic, immediately below the crural arch, 
 passes vertically upward, between the integuments and the superficial fascia, gives some 
 branches to the inguinal lymphatic glands, and terminates in the skin, near the umbili- 
 cus (arteria ad cutem abdominis, Haller). 
 
 The External Pudic Arteries. 
 
 The external pudic or genital arteries, also named scrotal in the male, and vulvar in the 
 female, arise from the inner side of the femoral : they are two in number (c c, fig. 214), 
 and are named the superior or sub-cutaneous, and the inferior or sub-aponeurotic. 
 
 The superior or sub-cutaneous arises immediately below the crural arch, passes trans 
 versely inward in the sub-cutaneous cellular tissue, and divides into two branches : a 
 superior, which passes to the pubic eminence, and an inferior, which is distributed to 
 the skin of the penis and scrotum in the male, and to the corresponding external labium 
 in the female. I have seen the dorsal artery of the penis arise from this vessel. 
 
 The inferior or sub-aponeurotic branch arises a little below the preceding, and some- 
 times even from the deep femoral ; it passes transversely inward, crosses the femoral 
 vein at right angles immediately below the point where it is joined by the saphenous 
 vein, so that this artery is generally received in the loop described by the upper end of 
 the saphenous vein : it soon perforates the fascia and becomes sub-cutaneous, and then 
 ramifies in the scrotum in the male, and in the external labium in the female. The 
 anastomoses of the superior and inferior external pudics, both with each other and with 
 those of the opposite side, are so free and large, that when one of them is cut across, it 
 becomes necessary to tie both of the cut ends of the vessel. These arteries are re- 
 Tnarkable on account of their relations with hernial tumours. 
 
 The Muscular Arteries. 
 The femoral gives off a great number of muscular and cutaneous branches, which have 
 received no particulai names. One, however, is usually described as the superficial m 
 
THE DEEP FEMORAL ARTERY. 563 
 
 greax muscular artery, which frequently arises from the deep femoral ; it passes trans- 
 versely between the sartorius and the rectus femoris, and immediately divides into as- 
 cending branches, which proceed to the iliacus, sartorius, and tensor vaginee femoris, and 
 into very large descending bra?iches, some of which are distributed to the rectus fem- 
 oris, passing in at its posterior surface, while others penetrate the vastus internus and 
 vastus externus. The last-mentioned branches can be traced as far as the lower part 
 of the triceps muscle ; and, indeed, the great muscular artery might be named the mus- 
 cular artery of the triceps extensor femoris, which ig,fig. 214) may arise from the deep 
 femoral artery. 
 
 The Deep Femoral Artery. 
 
 The deep femoral artery {profunda femoris ; d d', fig. 214.) is intended to supply the 
 muscles and integuments of the internal and posterior regions of the thigh.* 
 
 It arises from the back of the femoral, generally about one and a half or two inches 
 below the crural arch, about half way between the pubes and the lesser trochanter, very 
 rarely below this point, but more commonly above it. Thus the femoral often divides, 
 either about six lines below the crural arch, or immediately beneath and on a level with 
 it, into two equal and parallel branches, of which the external is the deep femoral, and 
 the internal the femoral properly so called. I have seen this subdivision, which bears a 
 rather close analogy to the bifurcation of the humeral artery into the radial and ulnar 
 in the axilla, take place above the crural arch, that is to say, in the external iliac artery. 
 Immediately after its origin, the deep femoral passes backward and outward, and then 
 vertically downward, gradually approaching the femur ; it is situated deeply behind the 
 femoral artery, but is separated from it by the femoral and deep femoral veins ; it runs 
 parallel to th'fe femoral artery, in front of the pectineus, and on the outer side of the vastus 
 internus ; having reached the upper border of the long adductor, it passes behind that 
 muscle to arrive between it and the short and great adductors, perforates the latter mus- 
 cle a little below the tendinous opening for the proper femoral artery, and terminates by 
 ramifying in the biceps and semi-membranosus. Sometimes the deep femoral perforates 
 the adductor magnus almost immediately, and at once becomes posterior to it. 
 
 Varieties of Origin. — In the history of the deep femoral artery, the varieties in its origin 
 are most important, considered in a surgical point of view. 
 
 The common femoral artery is very often divided prematurely into two equal and 
 parallel branches, the external of which is the deep femoral, and the internal the true or 
 superficial femoral artery, t This premature division may take place at a distance of 
 six lines below the crural arch, opposite this arch, or even beneath it. I have seen this 
 division, which bears a resemblance to the high division of the humeral artery into the 
 radial and ulnar arteries in the hollow of the axilla, to take place above the femoral arch, 
 consequently at the expense of the external iliac artery. Bums has seen this division 
 taking place in the pelvis three times ; Tiedemann, who has observed it on both sides, 
 thinks that it is only met with in small-sized individuals. In a case which Professor 
 Dubreuil has communicated to me, where the right femoral artery was divided higher 
 than usual, the epigastric artery, instead of being given off by the external iliac, came 
 from the deep femoral, and the anterior circumflex iliac artery came from the superficial 
 femoral artery. 
 
 In another case which has been furnished to me by the same observer, the external 
 iliac or femoral artery, in its passage below the crural arch, was divided into three branch- 
 es : the external branch was the superficial muscular, the internal branch was the deep 
 muscular, which, immediately after its origin, dipped between the muscles ; the middle 
 branch, which was of a larger size than the two others, was the true femoral artery. 
 The only anomalies in this case were in the origin of the branches ; in their distribution 
 they were as usual. 
 
 During its course, the deep femoral gives off a great number of collateral branches, 
 which are soon expended in the adjacent muscles, and most of which are unnamed. 
 Those that are named are the internal and external circumflex, and the several f erf orating 
 arteries. 
 
 The internal circumflex artery (e) is larger than the external, and is the first branch 
 given off from the deep femoral ; not unfrequently it arises from the femoral. I have 
 observed, however, that this only takes place when the deep femoral artery arose a lit- 
 tle lower down than usual. In a case of this kind, the origin of the deep artery took place 
 
 * It is the proper artery of the thigh, while the femoral itself may be regarded as the artery of the leg and 
 foot. 
 
 t This relation is the one which always exists when the deep femoral artery arises opposite or above the 
 femoral arch ; the deep femoral passes down close by the external side of the superficial femoral ; this latter 
 covers the vein : if, in a case of this kind, the femoral artery were to be tied, and the ligature were applied 
 only to one vessel, it would be to the deep artery, which holds the relations that generally belong to the trunk 
 of the femoral artery itself. 
 
 Tn a case exhibited at the Anatomical Society by M. Mercier, the deep femoral, which arose from the ante- 
 rior side of the common femoral six lines below the arch, descended downward before the feiii ral vein, which 
 it crossed opposite the opening for the scaphena vein, turned round this vessel to become the c<;f\i artery, and 
 coursed along as usual. In this case, the deep femoral gave off the external pudic iirteries 
 
564 ANGEIOLOGY. 
 
 more than two inches below the femoral arch. Sometimes the internal circamflex comes 
 from the external iliac artery. Whatever may be its origin, it almost immediately dips 
 backward, between the pectineus and the neck of the femur, round which it turns in the 
 same manner as the posterior humeral circumflex artery, so that it may be ruptured in 
 luxation of the femur inward : it escapes backward beneath the quadratus femoris, and 
 terminates by dividing into ascending branches, and into internal and external descend- 
 ing branches. 
 
 Opposite the pectineus, it gives off the following collateral branches : cae very re- 
 markable articular branch ascends along the capsular ligament, enters the hip-joint, passes 
 under the ligament which converts the cotyloid notch into a canal, and is distributed to 
 the synovial membrane, the adipose tissue, and the fibrous capsule of the joint : one or 
 more anastomotic branches communicate freely with the ramifications of the obturator 
 artery ; lastly, a great number of muscular branches, some of which are very small, and 
 pass in front of, while others, which are larger, run behind, the pectineus, and are distrib- 
 uted to the obturator externus, the pectineus, and the adductors : the largest is intended 
 for the adductor magnus. 
 
 The terminal branches are as follows : Ascending muscular branches, some of which are 
 external, and ramify in the glutaeus maximus, while others are internal, and are dis- 
 tributed to the ischiatic attachments of the biceps, semi-tendinosus, and semi-membra- 
 nosus muscles ; descending muscular branches, which ramify upon the anterior surface 
 of the biceps, semi-tendinosus, and semi-membranosus, upon the great sciatic nerve, 
 and also in the small muscles situated between the pelvis and the trochanter major ; 
 periosteal branches, of which some ramify upon the periosteum of the trochanter, other& 
 upon the posterior surface of the neck of the femur ; and, lastly, anastomotic branches, 
 which pass upon the obturator, gemelli, and pyriformis muscles, and anastomose freely 
 with the sciatic, glutaeal, internal pudic, and obturator arteries, but especially with the 
 sciatic and the obturator. 
 
 It follows, then, that the internal circumflex is an important means of communication 
 between the internal Uiac, and, consequently, the common iliac and the femoral ; for, 
 independently of the direct anastomoses above mentioned, there are a great number of 
 indirect communications in the substance of the muscles and upon the periosteum. 
 
 The external or anterior circumflex (/), smaller than the internal, sometimes arises di- 
 rectly from the femoral ; it is often given off from the profunda by a common trunk with 
 the great muscular artery of the triceps, and it may then be regarded as fonned by the 
 bifurcation of the profunda : it passes horizontally behind the rectus femoris, crossing 
 in front of the psoas and iliacus, to which it gives a rather large vessel, and then divides 
 into two branches : an ascending muscular, Avliich is distributed to the glutaeus minimus 
 and to the tensor vaginse femoris ; and a circumflex branch, properly so called, which 
 turns round the base of the great trochanter {f,flg. 215), dips into the substance of the 
 triceps, and expands into a great number of ascending branches, which anastomose w ith 
 the internal circumflex upon the outer surface of the great trochanter. Not unfrequent- 
 ly, an anastomosis is formed in front by a transverse branch between the internal and ex- 
 ternal circumflex arteries, by which the arterial circle of the hip-joint is completed. 
 
 The perforating arteries (r r,fig. 214) are both muscular and cutaneous, and are intend- 
 ed for the posterior region of the thigh : they vary in number from one to four, and are 
 all distributed in a similar manner. They perforate the tendinous attachments of the 
 adductor muscles to the femur, and, having reached the back of the thigh, they turn 
 horizontally round the bone, and divide into ascending and descending branches, which 
 form a series of loops or anastomotic arches in the substance of the muscles ; these 
 loops acquire a great size in cases where the femoral has been tied after Hunter's meth- 
 od, i. e., in the middle third of the thigh. 
 
 The first perforating artery {r,fig. 215), which is the largest, and sometimes repre- 
 sents two, or even the whole of the perforating arteries, passes through the great ad- 
 ductor about one inch below the lesser trochanter, between the horizontal and oblique 
 fibres of the muscle ; its ascending branch («) turns round the great trochanter, and anas- 
 tomoses with the internal circumflex and sciatic in the substance of the glutaeus maxi- 
 mus ; its descending branch (Z) is distributed to the vastus externus, the semi-tendinosus, 
 semi-membranosus, biceps, and adductor magnus muscles. Some branches ramify upon 
 the great sciatic nerve.* 
 
 I have seen an inferior perforating artery arise from the femoral, just where it passed 
 through the tendon of the adductor magnus. 
 
 The terminal branch (d',flg. 214) of the deep femoral constitutes the last perforating 
 artery, which is distributed in the same manner as the other arteries of that name. 
 
 The Popliteal Arteky. 
 When the femoral artery has perforated the tendinous portion of the adductor magnus, 
 it takes the name of the popliteal artery, which extends down to its division into the an- 
 terior tibial and tibio-peroneal arteries. 
 
 * The principal nutritious artery of the femur arises from the first or second perforating artery. 
 
THE POPLITEAL ARTERY. 
 
 ffe 
 
 The popliteal artery {o,figs. 215, 217) is the artery of the ham or popliteal space ; it 
 
 Fig. 215. 
 
 is bounded above (p,fig- 215) by the tendinous ring formed 
 in the adductor niagnus, and below (p, fig. 217) by the low- 
 er border of the popliteus muscle, at which place it is sit- 
 uated opposite the lower end of the upper fourth of the 
 leg.* Its length in an adult subject is about seven inches. 
 
 It passes vertically, or somewhat obliquely outward and 
 downward, the direction of the artery being represented 
 by a line extending from the inner surface of the femur to 
 the space between its two condyles. It is tortuous when 
 the leg is flexed upon the thigh, but it becomes straight 
 when the leg is extended, and may be ruptured by very 
 forcible extension. It has been proved by experiment, 
 that extension may be carried as far as to cause lacera- 
 tion of the ligaments of the joint, without rupturing the ar- 
 tery, t 
 
 Relations. — It is situated deeply in the whole of its 
 course, and it is in relation, behind, with the semi-mem- 
 branosus above ; lower down, with the popliteal fascia, 
 from which it is separated by a layer of fat of greater or 
 less thickness, according to the prominence of the ham- 
 string muscles ; below this, with the gastrocnemius and 
 plantaris muscles ; and still lower, with the soleus. The 
 popliteal vein lies behind and slightly to the outer side of 
 the artery, and then behind it, adhering rather firmly to 
 it. The internal popliteal nerve also lies upon it behind, 
 but is separated from it by a very thick layer of fat. The 
 veins and nerves both cross the artery beneath the gas- 
 trocnemius, so as to get to the inner side of the lower 
 portion of the vessel. 
 
 From these relations, it follows that the popliteal artery 
 may be exposed from behind in the whole of its extent, 
 but that it is deeper seated below than above. 
 
 hi front, it is in relation, from above downward, with 
 the adductor magnus ; with the internal surface of the fe- 
 mur, which appears to be expanded and become posterior, 
 so as to support the vessel ; with the knee-joint, with 
 which it is in direct contact ; and, lastly, with the popli- 
 teus muscle. The direct relation of the popliteal artery with the joint explains the fa- 
 cihty with which it may be lacerated when its tissue has been rendered fragile from or- 
 ganic change, and accounts for the frequency of aneurism in this region. 
 
 On the inner side, this artery is in relation with the semi-membranosus, the inner con- 
 dyle of the femur, and the inner head of the gastrocnemius. 
 
 On its outer side, it has the biceps, the outer condyle, the outer head of the gastroc- 
 nemius, and also the plantaris and soleus muscles. 
 
 Collateral Branches. — The popliteal artery gives off- from its posterior aspect several 
 small branches, which pass into the muscles of the ham ; most of them are not named ; 
 but there are some which are distinguished as the sural arteries : in front it gives sev- 
 eral arteries, named articular, because they surround the knee, like the collateral arter- 
 ies of the elbow-joint. The articular arteries are divided into superior, middle, and in- 
 ferior ; the superior and inferior would have been better named the collateral arteries of 
 the knee. 
 
 The sural arteries {g g,fig*- 215, 217) are two in number: one internal, for the innei 
 head of the gastrocnemius, and the other external, for the outer head of the same muscle. 
 Arising from the back of the popliteal artery, they pass downward and backward, are 
 separated from each other by the internal popliteal nerve, enter the anterior and inter- 
 nal surface of each head of the gastrocnemius a little before the two heads meet, and 
 may be traced down to the lower part of the fleshy belly of that muscle. Generally one 
 of their branches accompanies the external saphenous nerve from the popliteal space to 
 the upper part of the tendo Achillis. 
 
 The superior articular or collateral arteries of the knee are divided into internal and 
 external. 
 
 The internal superior articular arteries are sometimes three, but most commonly two 
 in number, one of which arises higher than the other ; their origin is subject to variety, 
 
 * The divisioa of the popliteal artery takes place sowetiraes higher, sometimes lower than usual. In a case 
 ■where its bifurcation was premature, the anterior tibial has been seen passing between the popliteus muscle 
 and the posterior face of the til)ia. 
 
 t I have had an opportunity of observing a case of luxation of the knee, with complete laceration of the 
 crucial ligaments, where the popliteal artery was left entire. 
 
566 ANGEIOLOGY. 
 
 but they are constant in their distribution. We sheill distinguish them as the first and 
 second. 
 
 The first internal superior articular artery, usually called the great anastomotic artery 
 of the knee, is the largest of the whole : it arises opposite the point where the femoral 
 becomes the popliteal artery, and sometimes even from the lower part of the femoral it- 
 self; it perforates the adductor magnus from behind forward, and immediately divides 
 into four descending branches: the first is a muscular branch {i,fig. 214), which enters 
 the substance of the vastus internus, passes inward and downward to reach the inner 
 border of the tendon of the triceps, and, opposite the base or upper border of the patella, 
 perforates the fibres of the muscle, becomes superficial, and runs transversely outward 
 along the base of the patella, and forms an anastomotic arch with the external superior 
 articular artery. The second and third branches are periosteal ; one of them passes be- 
 tween the triceps and the femur, with which it is in contact, and terminates above the 
 trochlea of that bone by anastomosing (at s) with the external superior and the second 
 internal superior articular arteries ; while the other runs along the adductor magnus, 
 being held down against it by a layer of fibrous tissue, and anastomoses with tlie second 
 internal superior articular artery, supplying its place when that vessel is only in a rudi- 
 mentary state. The fourth branch (A) accompanies and supplies branches to the inter- 
 nal saphenous nerve : it appears to be constant ; it is placed under the sartorius, along 
 which it runs, together with the internal saphenous nerve, continuing with it below that 
 muscle. 
 
 The second internal superior articular artery {h,figs. 215, 217) arises immediately above 
 the inner condyle of the femur, turns round it horizontally, and divides into condyloid 
 branches, which cover the condyles with their ramifications, and communicate partly 
 with the first internal superior articular artery, and partly with the external superior ar- 
 ticular artery coming from the opposite side. It also gives off a patellar branch, which 
 runs upon the borders of that bone, supplies the skin and the synovial membrane of the 
 knee-joint, and anastomoses with the internal inferior articular artery. 
 
 The external superior articular artery {i,figs. 215, 217) arises opposite the second in- 
 ternal superior, turns horizontally round the outer condyle of the femur, gives off some 
 ascending muscular branches, which ramify in the vastus externus, and then terminates 
 in three periosteal branches. One, which is superior and transverse, turns round the 
 lower end of the femur, and anastomoses with the corresponding branch of the second 
 internal superior articular ; another and inferior branch ramifies upon the inner condyle, 
 and anastomoses freely by a great number of branches with the external inferior articu- 
 lar ; the third is a more superficial branch for the patella, on the side of which bone it 
 runs, and near its upper border gives off a transverse twig, which anastomoses on the 
 upper border of the patella with a similar one from the internal superior articular arter- 
 ies, and a descending twig, which runs along the outer border of the bone, and anasto- 
 moses with the external inferior articular artery. 
 
 The inferior articular or collateral arteries of the knee are also divided into the internal 
 and the external. They both arise from the front of the popliteal artery, opposite the 
 middle of the knee-joint. 
 
 The internal inferior articular artery {c,fig. 217) runs downward and inward, and, hav- 
 ing reached the internal tuberosity of the tibia, turns horizontally forward, passes be- 
 neath the tendons of the semi-teHdinosus, semi-membranosus, and gracilis muscles, and 
 also beneath the internal lateral ligament of the knee, turns upward upon the inner side 
 of the anterior tuberosity of the tibia and ligamentum patellaj, describing a curve with 
 its concavity directed upward, and anastomoses either with the superior articular arter- 
 ies or with the anterior tibial recurrent. During its course it gives off ascending and 
 descending periosteal and osseous branches.* 
 
 The external inferior articular artery {b,fig. 217) arises opposite the internal vessel, 
 turns horizontally forward, not upon the external tuberosity of the tibia (for this is pre- 
 vented by the tibio-fibular articulation), but upon the convex borders of the external 
 semilunar cartilage, passes beneath the tendon of the biceps and the external lateral 
 ligament of the knee-joint, and terminates by dividing into an ascending branch, which 
 runs upward along the outer border of the patella, a descending branch, which anasto- 
 moses with the anterior tibial recurrent, and a transverse branch, which passes behind 
 the ligamentum patellae below the patella, and anastomoses with a similar branch from 
 the internal inferior articular. The inferior articular arteries complete the arterial circle 
 which surrounds the patella, and from which numerous branches are given off, some 
 covering the patella by their anastomoses, and others entering the bone directly through 
 the numerous foramina which exist upon its surface. 
 
 The middle articular arteries (*, fig. 215) consist of several small branches, which arise 
 directly from the front of the popliteal artery, or from the external inferior articular, run 
 from behind forward into the interior of the knee-joint, and are distributed in the inter- 
 condyloid notch to the crucial ligaments, the adipose tissue, the synovial membrane, and 
 
 * By osseous branches I mean those which enter the bone directly through the foramina, on the internal 
 and external tuberosities of the tibia. 
 
THE ANTERIOR TIBIAL ARTERY. 
 
 567 
 
 especiaDy to the lower extremity of the femur, which they penetrate through the large 
 foramina on the adjacent surface of each condyle. The middle articular artery or arter- 
 ies belong, therefore, to the knee-joint exclusively, and do not assist in the restoration 
 of an impeded circulation : in this respect they differ entirely from the other articular 
 arteries, which acquire a very considerable size when the principal trunk has been tied. 
 
 The Anterior Tibial Artery. 
 
 Opposite the lower border of the popliteus muscle, the pophteal artery divides into 
 two branches : an anterior, named the anterior tibial {a, Jig. 217) ; and a posterior, which 
 forms the continuation of the popliteal, and may be denominated the tibio-peraneal trunk 
 (/). This trunk soon subdivides into the posterior tibial (t) and the peroneal {k) arteries. 
 
 The anterior tibial artery {a, Jigs. 216, 217), the anterior branch of the bifurcation of 
 the popliteal, terminates opposite the dorsal annular ligament of the Fig. 216. 
 
 tarsus (J), Jig. 216), below which the vessel is named the dorsal artery 
 oj the foot (/). Immedidtely after its origin, it passes horizontally 
 forward, perforates the upper part of the interosseous ligament, is re- 
 flected over it, and descends vertically in front of it ; having reached 
 the lower fourth of the leg, it is directed somewhat obliquely inward, 
 following the direction of the external surface of the tibia, and then 
 passes under the annular ligament, at the lower border of which, as 
 stated, it terminates. 
 
 A line stretched from that process of the tibia, which has been de- 
 scribed as the tubercle of the tibialis anticus (Osteology, p. 278), to 
 the middle of the tibio-tarsal articulation, will indicate its direction 
 and course. 
 
 Relations. — The anterior tibial artery is situated very deeply, and 
 yet it can be exposed at any point ; it is in relation, behind, with the | f 
 interosseous ligament in its three upper fourths, and with the tibia in 
 its lower fourth ; it lies in contact with the interosseous ligament, 
 and is retained in its place by a layer of fibrous tissue, so that, after 
 amputation of the leg, it retracts between these two fibrous layers, 
 and is sometimes seized and tied with difficulty. 
 
 In front, it is covered successively by the tibialis anticus, the ex- 
 tensor longus digitorum, and the extensor proprius poUicis, the ten- 
 don of which crosses over it ; it is placed exactly along the cellular 
 interval between the tibijdis anticus and the extensor muscles ; and 
 the incision should, therefore, be made along the line corresponding 
 to that interval, in order to expose the artery when it is to be tied ; 
 lower down it is only separated from the skin by the fascia of the leg 
 and the projecting tendon of the extensor proprius pollicis, and hence 
 it may be compressed in this situation. UiPS?iiif <i 
 
 On the inner side, it is in relation with the tibialis anticus, then with 
 the tibia, and, lastly, with the tendon of the extensor pollicis, being 
 lodged in the same sheath- 
 
 On its outer side, it has the extensor longus digitorum, then the ex- 
 tensor pollicis, both of which afterward cross over it ; and, lastly, it 
 has only the fascia of the leg : the anterior tibial nerve runs along the 
 outer side of the artery in its whole extent. 
 
 Its collateral branches are very small and numerous, and are distrib- 
 uted to the muscles and the skin. Among them, the anterior tibial 
 recurrent, and the external and internal malleolar, require special notice. 
 
 The anterior tibial recurrent artery (c,Jig. 216) is sometimes of considerable size ; it 
 arises from the tibial, after that vessel is disengaged from the interosseous ligament, 
 passes obhquely upward and inward between the tibialis anticus and the external tuber- 
 osity of the tibia, with which it is in contact, and expands into diverging, periosteal, and 
 articular branches, some of which ascend and anastomose with the external inferior ar- 
 ticular of the knee, while others pass transversely, and anastomose with the internal in- 
 ferior articular. I have seen the anterior tibial recurrent, of large size, run transversely 
 below the patella, and terminate upon the internal tuberosity of the tibia. 
 
 The malleolar, which would be more correctly named articular arteries, are divided 
 into the internal and external. 
 
 The internal malleolar or articular artery (d) arises opposite the dorsal annular ligament 
 of the tarsus, passes transversely inward under the tendon of the tibialis anticus, and di- 
 vides into two branches : a deep, or articular, which dips perpendicularly into the ankle- 
 joint, and is distributed to that articulation; and a superjicial, or malleolar, properly so 
 called, which passes above the malleolus, and is distributed upon it, on the inner side 
 of the tarsus, as far as the internal plantar region, where it anastomoses with the branch- 
 es of the internal plantar artery. 
 
 The external malleolar or articular artery (I), larger than the preceding, vart-s much in 
 
568 ANGEIOLOGY. 
 
 its origin. Thus, it sometimes arises under the dorsal ligament of the tarsus, opposite 
 the internal malleolar ; it often arises from the tibial, about two or three inches above 
 the annular ligament. Sometimes it is derived from the posterior peroneal artery, and 
 perforates the lower part of the interosseous ligament. Lastly, and most commonly, 
 it arises by two roots ; one of which is small, but variable in size, and is derived from the 
 peroneal, while the other is larger, and is given off from the anterior tibial. 
 
 These differences of origin affect the course of the artery. When it arises under the 
 Ugament of the tarsus, it passes transversely outward, and then turns in front of the ex- 
 ternal malleolus to run forward, resting upon the tarsus. It receives the branch from 
 the posterior peroneal at the point where it changes its direction. In those cases where 
 it arises higher, it passes obliquely downward, in front of the external malleolus, and 
 then upon the outer side of the astragalus. In all cases, the external malleolar artery 
 runs forward on the outer side of the cuboid bone, and forms an anastomotic arch with 
 the dorsjd artery of the tarsus. It is in contact with the booes througliout its course, 
 and is crossed by the tendon of the extensor longus digitonim : it gives off malleolar 
 branches, which ramify upon the outer surface of the external malleolus ; very large ar- 
 ticular branches, which dip into the tibio-tarsal articulation ; and one, which I would es- 
 pecially notice, that enters the deep fossa between the astragalus and os calcis ; and, 
 lastly, external calcaneal branches, which pass under the tendons of the peroneus longus 
 and peroneus brevis, and ramify upon the outer side of the os calcis, where they termi- 
 nate by anastomosing with the peroneal artery, and with some branches of the external 
 plantar. Several of these branches are reflected upon the upper surface of the os calcis in 
 front of the tendo Achillis, and anastomose with branches from the posterior tibial artery. 
 
 The Dorsal Artery of the Foot. 
 
 The dorsal artery of the foot {dorsalis pedis, f,Jig. 216) is the continuation of the an- 
 terior tibial, which takes this name after emerging from below the dorsal annular liga- 
 ment of the tarsus ; it terminates in the sole of the foot, by becoming continuous with 
 the plantar arch. Not unfrequently this artery arises by two roots, one of them being 
 formed by the anterior tibial, which is much smaller than usual, and is, as it were, ex- 
 hausted near the ankle, and the other by the peroneal, which is then very large, and per- 
 forates the lower part of the interosseous ligament. In a few rare cases, the anterior 
 tibial is entirely wanting, and is represented by some small perforating branches from 
 the posterior tibial or the peroneal ; the dorsal artery of the foot is then wholly derived 
 from the peroneal. 
 
 The size of the dorsal artery of the foot is also subject to variety; it generally bears 
 a direct proportion to that of the anterior tibial, which I have seen as large as the poste- 
 rior tibial and peroneal arteries together, while it has an inverse ratio to that of the two 
 last-mentioned vessels combined. 
 
 The dorsal artery runs horizontally and directly forward upon the dorsum of the foot, 
 as far as the posterior extremity of the first interosseous space, at which point it bends 
 downward at a right angle, perforates that space like a perforating artery, and termi- 
 nates by becoming continuous with the plantar arch. 
 
 The direction of the dorsal portion of this artery is marked by a line extending from 
 the middle of the tibio-tarsal articulation to the posterior extremity of the first interos- 
 seous space. 
 
 Relations. — It lies in contact with the bones of the tarsus, in which position it is re- 
 tained by a layer of fibrous tissue. It is separated from the skin by the fascia of the 
 foot, and also anteriorly by the inner portion of the extensor brevis digitorum. It runs 
 along the outer side of the tendon of the extensor proprius pollicis, which projects so as 
 to raise the integuments from the vessel ; it may be exposed in its entire length by cut- 
 ting along the outer border of that tendon. It is not uninteresting to remark that, un- 
 der the dorsal ligament of the tarsus, this artery is situated in the same sheath as the 
 tendon of the extensor proprius pollicis. 
 
 Its collateral branches are internal and external. 
 
 The internal branches are numerous, but are not named ; they ramify upon the inner 
 side of the tarsus, and anastomose upon the inner border of the foot, either with each 
 other, with the internal malleolar arteries, or with the internal plantar artery. One of 
 them may be described under the name of the internal tarsal artery, a branch which 
 has a remarkable course : it passes obliquely forward and inward as far as the posterior 
 extremity of the first metatarsal bone, and is sometimes continued along the inner side 
 of that bone to form the internal collateral artery of the great toe ; at other times it is 
 reflected under the first metatarsal bone, and anostomoses directly with the internal 
 plantar artery, after having given off a great number of branches to the inner side of the 
 metatarso-phalangal articulation of the great toe. 
 
 Among the external branches there are two which require particular description, viz., 
 the dorsal artery of the tarsus, or the external tarsal, and the dorsal artery of the metatarsus 
 or the metatarsal artery. 
 
 The external tarsal artery {g) varies in its size, which almost always bears an inverse 
 
THE TIBIO-PERONEAL ARTERY. 
 
 569 
 
 proportion to that of the external malleolar and metatarsal arteries. I have seen it as 
 large as the dorsal artery of the foot, by the bifurcation of which vessel it appeared to be 
 formed. 
 
 It passes transversely outward under the extensor brevis digitorum, anastomoses 
 freely with the external malleolar artery, and gives off the following branches : some 
 which ramify upon the outer side of the os calcis, and anastomose with the peroneal ; a 
 branch which runs upon the cuboid bone, sometimes being so large as to be regarded 
 the continuation of the artery, and then passes under the sole of the foot to anastomose 
 with the external plantar ; and, lastly, some branches in front, which anastomose with 
 the metatarsal artery, the place of which vessel it sometimes partially supplies, by giv- 
 ing off the dorsal interosseous arteries. In one case, where the external tarsus artery 
 was very large, it passed transversely outward as far as the outer surface of the cuboid 
 bone, was reflected backward on the outer surface of the calcaneum, and there anasto- 
 mosed very freely with the external malleolar and the peroneal arteries. In another 
 case, the external tarsal artery divided into two branches, one of which ran transversely 
 outward and reached below the sole of the foot, while the other formed the dorsal inter- 
 osseous artery of the fourth interosseous space. 
 
 The metatarsal artery (h) generally arises from the front of the dorsal artery of the 
 foot, opposite the posterior extremity of the first interosseous space, sometimes by a 
 common trunk with the external tarsal just described. According to the most regular 
 distribution, it passes transversely outward, opposite the posterior extremities of the 
 several metatarsal bones, and constitutes the dorsal arch of the metatarsus (?). 
 
 Three branches given off from the convexity of this arch, which is directed forward, 
 are named the dorsal interosseoas arteries {I I). They run along the dorsal surface of the 
 second, third, and fourth interosseous spaces, and having arrived opposite the metatarso- 
 phalangal articulations, divide into two collateral branches for the corresponding toes. 
 During its course along its own interosseous space, each dorsal interosseous artery re- 
 ceives two perforating branches, viz., a posterior perforating artery, opposite the posterior 
 extremity of the interosseous space, and an anterior perforating, opposite the anterior ex- 
 tremity of the same space. This explains the otherwise sin- 
 gular fact, that the dorsal interosseous arteries are increased 
 in size opposite the posterior and anterior extremities of their 
 respective spaces. In some subjects, the dorsal interosseous 
 arteries are derived exclusively from the perforating arteries. 
 
 It is not very rare to find the metatarsal and the dorsal inter- 
 osseous arteries wanting ; their places are then supphed by the 
 plantar interosseous arteries. 
 
 The dorsal interosseous artery of the first interosseous space (n) 
 is given off directly from the dorsal artery of the foot, at the 
 point where that artery dips into the first interosseous space ; 
 it is larger than the other dorsal interosseous arteries, but is 
 distributed in a similar manner. 
 
 The dorsal interosseous artery of the second space is also 
 rather frequently derived directly from the dorsalis pedis. 
 
 The Tibio-peroneal Artery. 
 
 '* The tihio-peroneal artery or trunk (^f,fig- 217), the posterior 
 branch of the bifurcation of the popliteal artery, is bounded 
 above by the origin of the anterior tibial, and below by its sub- 
 division into two branches, viz., the posterior tibial (Z) and the 
 peroneal (^■). It is from one inch to eighteen lines in length, 
 sometimes it is not more than six lines, and it may be two or 
 even three inches ; I have seen it extend as low as the inner 
 part of the os calcis, where it divided into the internal and ex- 
 ternal plantar arteries.* ' 
 
 It forms the continuation of the popliteal in regard to direc- 
 tion, and is in relation with the soleus behind and the muscles 
 of the deep layer in front ; the posterior tibial nerve crosses 
 behind to get to its outer side below. 
 
 The collateral branches of the tibio-peroneal artery are, first, 
 an internal recurrent branch, which perforates the soleus from 
 behind forward, turns round upon the inner border of the tibia, 
 is reflected upward, and anastomoses with the internal inferior 
 articular artery upon the internal tuberosity of that bone ; sec- 
 ondly, the nutritious artery of the tibia (s) ; and, lastly, a single 
 large branch, or several branches, to the soleus muscle, which 
 
 * M. Dubreuil has communicated to me n case in which the tibio-peroneal trunk continued undivided al' 
 along the posterior face of the peroneus, and gave off the posterior tibial artery only at the lower part of the leg 
 
 4 
 
';:StO .'/J?.-.' ANGEIOLOGY. 
 
 they enter near its peroneal attachments, and then anastomose with the anterior tibial 
 and the external inferior articular. When the tibio-peroneal artery is short, the branch 
 to the soleus is derived from the peroneal artery. 
 
 The Peroneal Artery. 
 
 The peroneal artery (i) extends from the bifurcation of the tibio-peroneal trunk to the 
 OS calcis. It is generally smaller than the posterior tibial, and even than the anterior 
 tibial, and bears an inverse proportion to the size of the two, more particularly to that 
 of the anterior tibial, the place of which it often partially supplies. In some cases it is 
 itself replaced by some small branches derived from the posterior tibial.* 
 
 It descends vertically along the posterior surface of the fibula, from which it is separ- 
 ated by the flexor longus pollicis ; it is covered by the soleus, and dips below between 
 the flexor longus pollicis and the tibialis posticus, to reach the interosseous ligament, at 
 the lower part of which it divides into a posterior and an anterior branch. 
 
 Its collateral branches are, first, posterior ones, which are very numerous, and supply 
 the soleus ; the highest of these are of considerable size, and often arise from the tibio- 
 peroneal artery. Secondly, there are internal and external branches, which pass to the 
 deep-seated muscles of the leg : among the external branches is the nutritious artery of 
 the fibula ; and among the internal branches a transverse or oblique anastomotic twig 
 may be specially noted, which extends from the peroneal to the posterior tibial. Some- 
 times this anastomotic branch is very large, and, in that case, the posterior tibial is more 
 slender than usual up to that point, but increases in size after receiving this addition, 
 and afterward gives off the plantar arteries. 
 
 Terminal Branches. — The anterior terminal branch, named the peroneal perforating, oi 
 the anterior peroneal artery {g,fig. 216), perforates the lower part of the interosseous lig- 
 ament, descends upon the lower end of the tibia, and anastomoses with the external 
 malleolar artery, which is sometimes formed by it. This peroneal perforating branch, 
 which is generally very small, is sometimes as large, or even larger, than the posterior 
 branch, and then supplies the place of the lower part of the anterior tibial, and forms the 
 dorsal artery of the foot ; the anterior tibial is then very small. There almost always 
 exists a trace of this distribution in the presence of a small branch, which anastomoses 
 with the anterior tibial. 
 
 The posterior terminal branch (I, Jig. 217) of the peroneal artery, which might be called 
 the external calcaneal, forms the continuation of that vessel, and gains the posterior as- 
 pect of the external malleolus, to which it is applied, after running along the outer bor- 
 der of the tendo Achillis, being separated from the skin by the fascia of the leg and an- 
 other layer of fibrous tissue. It gives off to its inner side, opposite the posterior border 
 of the lower end of the tibia, a transverse branch, which anastomoses with the posterior 
 tibial artery. It then ramifies upon the outer surface of the os calcis, supplies the cal- 
 caneal attachments of the muscles of the sole of the foot, and also the skin of the heel, 
 and anastomoses with the external malleolar, and also with the external plantar artery. 
 Some small ascending branches pass above the os calcis, and anastomose in front of the 
 tendo Achillis with corresponding branches of the posterior tibial. I have seen the ev 
 ternal calcaneal artery derived from the posterior tibial. 
 
 The Pbsterior Tibial Jlrtery. 
 
 The posterior tibial artery (t, Jig. 217) is the internal branch of the bifurcation of the 
 tibio-peroneal artery or trunk, and having entered a groove on the os calcis, beneath the 
 internal annular ligament of the tarsus {t,Jig. 218), terminates by dividing into the inter- 
 nal (a) and the external {b) plantar arteries. It is larger than the other arteries of the leg, 
 and is generally inversely proportioned to the anterior tibial and the peroneal. Thus, in 
 a subject in which the anterior tibial and the dorsal artery of the foot were very large, 
 the posterior tibial and the internal plantar were scarcely one third of their ordinary size. 
 
 The posterior tibial artery is at first directed obliquely inward, and then vertically 
 downward ; and it is in relation, in front, with the tibialis posticus ; lower down, with the 
 flexor communis digitorum, which separates it from the tibia ; below that, with the pos- 
 terior border of the internal malleolus, from which it is separatad by the tendons of the 
 tibialis posticus and flexor longus digitorum ; still lower, with the ankle-joint ; and, last- 
 ly, while under the arch of the os calcis, with the groove for the tibialis posticus. Be- 
 hind, it is at first covered by the gastrocnemius and soleus ; and in the lower third of the 
 leg, where these muscles are wanting, it is in relation with the inner border of the tendo 
 Achillis, and is separated from the skin by two fibrous layers. The internal popliteal 
 nerve runs along the outer side of this artery. 
 
 It follows, then, that the posterior tibial artery may be compressed and exposed in the 
 whole of the lower third of the leg. 
 
 * In a case where the anterior tibial, being very small, disappeared at the union of the two superior with 
 the inferior third of the leg, the peroneal artery, which was twice as large as the posterior tibial, arose on 
 the inside of this latter artery, which it crossed at a very acute angle, to become external. When it had 
 reached the lower third of the leg, it passed down close to the posterior surface of the interosseous ligament 
 which it traversed at its inferior portion, and then formed the artery of the foot. 
 
THE INTERNAL AND EXTERNAL PLANTAR ARTERIES. 
 
 571 
 
 The collateral branches of the posterior tibial artery are very ermall, and do not require 
 any particular description : some of them are posterior, and pass to the soleus and gas- 
 trocnemius ; others are anterior, and supply the deep-seated muscles, and the perios- 
 teum of the tibia. The principal nutritious artery of the tibia, which we have stated to 
 arise from the tibio-peroneal trunk, is often given off by the posterior tibial. Most of the 
 lower internal branches perforate the flexor longus digitorum, turn round over the inter- 
 nal border of the tibia, and ramify in the periosteum and integuments. Lastly, opposite 
 the .posterior border of the lower end of the tibia, we find a small transverse branch, 
 which anastomoses with a corresponding branch, already mentioned as arising from the 
 peroneal artery. 
 
 Beneath the concavity on the under surface of the os calcis, the posterior tibial gives 
 off before its subdivision several calcaneal branches, some of which ramify upon the in- 
 ternal surface of the os calcis, while others mount up above that bone, apd anastomose 
 with twigs from the peroneal ; also, some articular branches for the tibio-tarsal and as- 
 tragalo-calcaneal articulations ; and, lastly, some branches which pass up upon the inner 
 boixler of the tarsus, to anastomose with the internal malleolar artery. 
 
 The Internal and External Plantar Arteries. 
 
 The internal and external plantar arteries, the terminal branches of the posterior tib- 
 ial, conunence in the concavity beneath the os calcis, under the internal annular ligament 
 of the tarsus. 
 
 The internal plantar artery ( a, fig. 218) is generally much smaller than the external ; it 
 passes horizontally forward, along the inner side of the sole of the j^g. 218. 
 
 foot, between the abductor poUicis and the tendons of the flexor 
 longus digitorum ; more anteriorly, it is subjacent to, i. e., farther 
 from the skin, than the flexor brevis digitorum ; it supplies the 
 muscles ]n question, gives off several ascending and oblique branch- 
 es to the numerous articulations of the tarsus, anastomoses freely 
 by some internal branches with the internal malleolar and internal 
 tarsal arteries, and ends in different ways. The following is its most 
 common mode of termination : having reached the posterior extrem- 
 ity of the first metatarsal bone, it divides into two branches ; one of 
 which is internal, and runs along the outer side of the abductor pol- 
 licis, and deviates a little, so as to form the internal collateral artery 
 (i) of the great toe : the other is external, varies much in size, and 
 anastomoses (at g) with the common trunk of the collateral arteries 
 of the first and second toe. We may regard as its terminating branch 
 a cutaneous artery, which perforates the plantar fascia, and is distrib- 
 uted to the skin and sub-cutaneous cellular tissue on the inner side 
 of the foot. I have seen the internal plantar artery very small, and 
 terminating in the flexor brevis pollicis. 
 
 The external plantar artery (6) forms the continuation of the pos- 
 terior tibial in reference to its size ; but in certain cases, howev- 
 er, it is not larger than the internal plantar arteiy. It passes 
 obliquely downward, outward, and forward, accompanied by the 
 external plantar nerve, under the os calcis, between the flexor brevis digitorum, which 
 is below or superficial to it, and the flexor accessorius, which is above or deeper : as 
 soon as it gains the outer border of the flexor brevis digitorum, upon the aponeurotic 
 septum between this muscle and the abductor of the little toe, it turns directly forward, 
 and having reached the under surface of the posterior extremity of the fifth metatarsal 
 bone, it changes its direction, leaves the nerve, and curves inward and forward, towards 
 the posterior extremity of the first interosseous space (at g), where it inosculates with 
 the dorsal artery of the foot : this curved portion of the artery, extending from the fourth 
 to the first interosseous space, constitutes the plantar arch, which is formed by tlie junc- 
 tion of the dorsal artery of the foot with the external plantar artery ; it runs obliquely 
 below the posterior extremities, or sometimes the middle of the metatarsal bones, be- 
 tween them and the adductor of the great toe, by which, and all the other muscles of 
 the middle plantar region, it is covered in below ; and it establishes a free and uninter- 
 rupted communication between the anterior and posterior tibial arteries. I have seen 
 the plantar arch formed exclusively by the dorsal artery of the foot, the external plantar 
 being very small, and losing itself in the abductor and flexor brevis minimi digiti ; at 
 other times, the external plantar artery only communicates with the plantar arch by 
 means of some small branches. 
 
 Before it constitutes the plantar arch, the external plantar artery gives off an inferior 
 calcaneal branch (c), which passes transversely outward, in front of the tubercles on the 
 lower surface of the os calcis, above the flexor brevis digitorum, and terminates in the 
 muscles of the external plantar region ; also, some muscular branches to the muscles of 
 the external plantar region, the flexor brevis digitorum, and the flexor accessorius ; and, 
 lastly, some periosteal, osseous, and articular branches, to Jhe bones and to the corre- 
 sponding articulations of the tarsus. 
 
Wffi ANGEIOLOOY. 
 
 The plantar arch itself gives off superior and anterior branches. The superior branch- 
 es, or the posterior perforating arteries, pass perpendicularly upward, through the poste- 
 rior extremities of the interosseous spaces, and anastomose with the dorsal interosse- 
 ous arteries. There are only three posterior perforating arteries, which belong to the 
 second, third, and fourth (d) interosseous spaces : the dorsal artery of the foot repre- 
 sents the perforating artery of the first interosseous space. 
 
 The anterior branches are five in number ; of these, four are plantar interosseous or 
 digital arteries, and are distinguished by the numerical names of first, second, and third, 
 proceeding from within outward ; the fifth anterior branch is the external collateral ar- 
 tery of the little toe. 
 
 All the plantar interosseous or digital arteries (e) run forward in the corresponding in- 
 terosseous spaces, and then between two of the metatarso-phalangal articulations ; op- 
 posite the anterior extremity of the metatarsal bone, each digital artery gives off a small 
 anterior perforating branch (as at s), which anastomoses with the corresponding dorsal 
 interosseous artery ; having reached beyond the posterior extremity of the first phalan- 
 ges of the toes on either side, each digital artery divides into two branches, which con- 
 stitute the internal and external eoUateral arteries (/) of the corresponding toes, and are 
 distributed in precisely the same manner as the collateral arteries of the fingers ; that 
 is to say, the internal and external collaterals of each toe anastomose by a small trans- 
 verse branch opposite the second phalanx, anastomose again opposite the middle of the 
 last phalanx, and are almost entirely distributed to the skin. 
 
 The first plantar interosseous or digital artery (arteria magna poUicis pedis) recjuires a 
 special description. It is very large, and arises precisely at the point {g) where the dor- 
 sal artery of the foot terminates in the plantar arch, so that it appears to result from the 
 bifurcation of the dorsal artery of the foot ; it passes under the first metatarsal bone, 
 and, having arrived behind the anterior extremity of that bone, it gives off a branch from 
 its inner side, which sometimes forms the internal collateral artery of the great toe ; it 
 then passes outward to reach the space between the metatarso-phalangal articulations 
 of the first and second toes, and divides into the external collateral artery of the great toe 
 {h) and the internal collateral artery of the second toe (/). Opposite the middle of the first 
 phalanx of the great toe, its external collateral artery gives off a branch inward, which 
 anastomoses with the internal collateral artery, and sometimes even constitutes that 
 artery. 
 
 The external collateral artery of the little toe (l), which may almost be regarded indiffer- 
 ently as arising from the external plantar artery, or from the plantar arch, passes for- 
 ward under the flexor brevis of the little toe, and terminates along the outer border of 
 that toe, by anastomosing with the tarsal and metatarsal arteries derived from the dor- 
 sal artery of the foot. I have seen this branch give origin to both the external and in 
 temal collateral arteries of the little toe. 
 
 Comparison between the Arteries of the Upper and Lower Extremities. 
 
 All the arteries of the lower extremities are derived from two primitive trunks, viz., 
 the right and left common iliac arteries, each of which soon subdivides into an internal 
 and external iliac. The arteries for the upper extremities and head arise from three 
 primitive trunks, the first being the brachio-cephalic, or innominate artery, which soon 
 subdivides into the right common carotid and right sub-clavian ; the second is the left 
 common carotid, and the third the left sub-clavian, which may justly be regarded as 
 forming together a single primitive trunk. There are, then, ultimately, four trunks for 
 the upper as well as the lower parts of the body. 
 
 The common carotid arteries, distributed as they are to the head, cannot be compared 
 to the internal iliacs, which are given to the pelvis and the organs contained in the pel- 
 vic cavity ; but as the pelvis corresponds to the shoulder, we may find some analogy, if 
 not in origin, at least in distribution, between the arteries of the one and of the other. 
 
 The external iliac corresponds to the sub-clavian ; the more numerous collateral 
 branches of the latter are in part represented by the branches of the internal iliac to the 
 walls of the pelvis. Thus, the os coxae, as well as the scapula, is, as it were, girdled by 
 an arterial circle. The posterior scapular artery, which runs along the vertebral border 
 of the scapula, represents the circumflex iliac, which turns round the crest of the ilium, 
 and is distributed to the muscles of the abdominal parietes in the same manner as the 
 posterior scapula is distributed to the serratus magnus and the rhomboideus. I will not 
 carry the analogy farther, by comparing the supra-scapular, sub-scapular, and internal 
 mammary arteries with the sciatic, gluteal, obturator, and internal pudic. 
 
 The axillary and brachial arteries correspond to the femoral and popliteal. 
 
 The deep humeral artery represents the deep femoral ; the circumflex branches of the 
 femoral correspond to the circumflex and sub-scapular branches of the axillary : the anas- 
 tomoses of the femoral circumflex arteries with the obturator, gluteal, and sciatic, cor- 
 respond to the anastomoses of the circumflex and sub-scapular branches of the axillary 
 with the supra-scapular and posterior scapular branches of the sub-clavian. 
 
 The popliteal portion of the femoral represents that part of the brachial which is sit- 
 
THE VEINS. 573 
 
 uated opposite the bend of the elbow ; the internal and external collateral arteries deri- 
 ved from the brachial, together with the radial, ulnar, and interosseous recurrents, form 
 anastomotic circles around the elbow, which are exactly analogous to those formed by 
 the superior articular arteries given off from the popliteal with the inferior articular ar- 
 teries and the anterior tibial recurrent artery. 
 
 The bifurcation of the pophteal into the anterior tibial and the tibio-peroneal trunk 
 represents the bifurcation of the brachial into the radial and ulnar : the anterior tibial 
 corresponds to the portion of the radial situated in the forearm ; the dorsal artery of the 
 foot to the carpal portion of the radial ; and the plantar arch, which is continuous with 
 the dorsal artery of the foot, represents the deep palmar arch, which is the continuation 
 of the radial in the hand. 
 
 The tibio-peroneal trunk corresponds to the commencement of the ulnar artery, the 
 posterior tibial artery to the trunk of the ulnar, and the peroneal artery to the interos- 
 seous artery of the forearm. Just as the peroneal often gives origin to the dorsal ar 
 tery of the foot, so does the interosseous sometimes give off the carpal portion of the 
 radial. 
 
 The plantar arch is represented by the deep p^dmar arch ; the plantar interosseous and 
 the collateral arteries of the toes, by the palmar interosseous and the collateral eirteries 
 of the fingers. 
 
 If it be asked why there is no superficial plantar arch corresponding to the superficial 
 palmar arch, it may be said, first, that the arteries of the dorsum of the foot are much 
 larger than those on the back of the hand ; and, secondly, that the hollow, vaulted form 
 of the sole of the foot preserves the plantar arch from the compression to which the pal- 
 mar arch is liable in consequence of the flattened form of the hand.* 
 
 THE VEINS. 
 
 Definition. — The Venous System. — Origin of the Veins. — Course. — Anastomoses and Fiex- 
 uses. — Varieties. — Termination. — Valves. — Structure. — Preparation. — Method of Descrip- 
 tion. 
 
 The veins (0^ei/') are those vessels which convey the blood back from the extremitie& 
 to the heart. They are also called les vaisseaux a sang noir, in opposition to the arteries, 
 which are then named les vaisseaux d sang rouge ; but these terms are incorrectly appli- 
 ed, for the pulmonary veins convey red, and the pulmonary artery black blood. 
 
 There are two venous systems, corresponding to the two arterial systems, viz., the 
 pulmonary venous system, through which the blood returns from the lungs to the left au- 
 ricle, and the general venous system, which conveys the blood from all parts of the body 
 to the right auricle. There is also a third venous system, the system of the vena porta, 
 which is an appendage of the general venous system, and, as we shall see, forms by it- 
 self a perfect circulatory apparatus. In the foetus there is a fourth venous system na- 
 med the umbilical. 
 
 General View of the Venous System. 
 
 Both the general venous system and the pulmonary venous system, regarded as a 
 whole, resemble the roots of a tree, the trunk of which, in the former case, would cor- 
 respond to the right auricle, and, in the latter, to the left auricle. While a single arte- 
 rial trunk, the aorta, gives origin to the general arterial system, the corresponding veins 
 terminate in three venous trunks, viz., the superior and inferior venae cavae and the coro- 
 nary vein ; and so in the pulmonary venous system there is a single arterial trunk, the 
 pulmonary artery, to four veins, two for each lung. 
 
 Each artery has generally two accompanying veins, which are called its satellite veins 
 {vena comites), and bear the same name as the artery ; besides these, there exist in some 
 parts certain superficial or sub-cutaneous veins, which form a system totally apart from the 
 arteries, and may be regarded as supplementary veins. 
 
 The number of the veins is, therefore, much greater than that of the arteries. This 
 rule, however, has some exceptions ; in fact, there is only one accompanying vein for 
 the great arterial trunks, and even for some arteries of moderate size ; lastly, in some 
 few instances, there is but one vein to two arteries. Thus, there is only one superior 
 and one inferior mesenteric, one renal, and one external iliac vein, each of which cor- 
 responds to the artery of the same name ; but there is but one umbilical vein to two um- 
 bilical arteries, and there are several supra-renal arteries, but only one supra-renal vein. 
 
 It is impossible to estimate the size of the veins with accuracy, in consequence of the 
 variations to which they are liable from their extreme dilatability. Hence the very dif- 
 ferent results obtained by authors in this respect. According to Haller, the capacity of 
 
 * [For farther information concerning varieties in the distribution of arteries, the reader is referred to the 
 " Anatomy of the Arteries, with its Applications to Pathology and Operative Sursery," by Professor R. Qaain, 
 with drawings by J. Maclise, 1841, 1842.] 
 
ANGEIOLOGY. 
 
 the veins is to that of the arteries as two to one ; according to Borelh, as four to one 
 according to Sauvages, as nine to four. 
 
 The entire venous system represents a truncated cone, the apex of which corresponds 
 to the heart, and the base to the origins of the veins. From this disproportion between 
 the total area of the smaller veins, and the area of the trunks in which they terminate, 
 it follows that, in the course of the circulation, the blood passes from a wider to a nar- 
 rower space ; an arrangement which tends to accelerate the progress of the fluid. 
 
 The study of the veins includes the consideration of their origin, course, anastomoses, 
 relations, termination, and structure. 
 
 Origin of the Veins. 
 
 The veins are continuous with the arteries ; a fact that is proved by the facility with 
 which even very coarse injections will pass from the arteries to the veins, and is also 
 most satisfactorily shown by examining the circulation in the mesentery of the frog. In 
 some parts, instead of the communication between the arteries and veins being direct, 
 it is established by means of an intermediate vascular network or spongy tissue, which 
 is entirely venous : of this we have an example in the corpus cavernosum penis. Last- 
 ly, the facihty with which injections forced into the veins from the trunks towards the ex- 
 tremities escape upon the surface of the mucous membranes, would seem to establish 
 the fact of these vessels arising by open mouths at the surface of those membranes. 
 HaUer admitted the existence of absorbent veins arising from all the free surfaces.* 
 
 Course. 
 
 Immediately after their origin, the veins form networks, from which small branches 
 are given off to anastomose together and form larger and larger networks : from these, 
 again, proceed larger branches, which become successively united, just as the arteries 
 are successively divided ; that is to say, the smaller branches unite to form larger ones, 
 and these still larger branches, which are at length united into the venous trunks. In 
 the limbs, the veins are divided into the superficial and the deep. The deep veins, which 
 accompany the arteries, have similar relations with the bones, muscles, nerves, fasciae, 
 and skin, as those vessels. The deep veins are always in contact with the arteries, 
 and are contained in the same fibrous sheaths. All attempts to ascertain any law by 
 which the relations of the veins with the arteries are regulated have been unsuccessful. 
 Indeed, the relative position of the two kinds of vessels, although constant, does not 
 seem to follow any general rule. The close relations between the arteries and veins, 
 interesting as they are to the surgeon, who is required to separate the veins carefully 
 from an artery before tying the latter, are no less so to the physiologist. The shock 
 communicated to the blood in the venae comites by the pulsations of their correspond- 
 ing artery, must assist the circulation of that fluid. In some cases of hypertrophy of the 
 heart, I have seen the blood issue in jets from a vein as if it were from an artery. 
 
 When, as it in some places happens, the deep veins do not accompany the arteries, 
 there is always some special roason which observation may determine. For example, 
 the cerebral sinuses, which are really veins, do not accompany the arteries ; nor are the 
 hepatic veins, the ophthahnic vein, and the vena azygos, satellites of their correspond- 
 ing arteries. 
 
 The superficial veins exist only in parts where the circulation in the deep veins is liable 
 to be obstructed during the exercise of those parts. In fact, as the venous blood does 
 not circulate like the arterial, under the influence of an impelling agent directly connected 
 with them, it is retarded by the slightest cause, and hence, therefore, the necessity foi 
 additional means of circulation. 
 
 The superficial veins, therefore, constitute, in reference to the deep veins, a collateral 
 route for the venous blood, especially during the contraction of the muscles of the uppei 
 and lower extremities, as we find in persons who exercise their limbs much. I have 
 shown that the tongue, as well as the extremities, is provided with a superficial and a 
 deep set of veins. The superficial veins are situated between the investing aponeuroses 
 of the muscles and the skin, from which they are separated by a very thin layer of fascia : 
 they are accompanied by the sub-cutaneous nerves and lymphatics. 
 
 From this description it follows, that such of the deep veins as accompany the arteries 
 do not require any special description, because they have the same distribution and the 
 general relations as the arteries : the description of the venous system will therefore be 
 confined to an examination of such veins as pursue a course independent of that of the 
 arteries. 
 
 Anastomoses and Plexuses. 
 The anastomoses of the veins are more numerous than those of the arteries, and they 
 take place by means of much larger vessels ; an arrangement which compensates for 
 the want of an impelling organ directly connected with them. Thus, anastomoses by 
 
 * [The eseapfi of injections upon mucous membranes is due to rupture or transudation ; the existence oJ 
 veins having open mouths tipon these or other free surfaces is now denied by the best authorities.! 
 
THE VEINS. 575 
 
 direct inosculation, by lateral, transverse, or oblique communications, and anastomoses 
 by convergence, are found in every situation, and with all conceivable varieties. The 
 branches of the veins form lozenge-shaped meshes ; and both the trunks and the branches 
 communicate freely with each other ; that is to say, the superficial with the deep set, the 
 veins of the superficial set and those of the deep set among each other, and the vena 
 cava superior with the vena cava inferior ; so that we may say that the whole venous 
 system forms one vascular network, and it is by these free communications that such 
 obstacles as impede, or even completely intercept the course of the blood in a given part, 
 are rendered incapable of stopping it altogether. In order to intercept the course of the 
 venous blood completely, it would, in fact, be necessary to obliterate, not only the prin- 
 cipal trunk, but also all the collateral channels. One remaAable mode of anastomosis 
 is the following : a collateral vein arises from some point of a particular vein, and termi- 
 nates at a greater or less distance in the same vein, like a canal intended to unite two 
 distant points of the same stream ; this collateral channel is intended to receive a num- 
 ber of veins, which would otherwise have terminated in the principal vessel. The fol- 
 lowing is a variety of this kind of anastomosis : one vein divides into two of equal size, 
 which diverge from each other at a very acute angle, or, rather, run parallel, and reunite 
 at a greater or less distance. The saphenous vein often presents this arrangement. 
 
 A venous plexus, which consists of a complicated network of vessels, is nothing more 
 than the highest development of an anastomosis : venus plexuses are found in parts 
 where the circulation is liable to be retarded, or in organs whose functions require a large 
 aflJux of blood ; example, the vesical, uterine, and spermatic plexuses. 
 
 The veins are rarely tortuous, like the arteries, but are generally straight ; a circum- 
 stance which also helps to lessen the effects of the deficiency of a direct impelling organ ; 
 for tortuosities, by multiplying the points of friction, would evidently retard the flow of 
 blood in the veins. The great veins are not at all tortuous, but the smallest veins, and 
 those forming the plexuses, are distinctly so. The tortuosities of veins are generally 
 regarded as the result of their too great development. Thus, hypertrophied veins, 
 whether varicose or not, always pursue a distinctly zigzag course. 
 
 Varieties. 
 
 The varieties in the size, the anastomoses, and the terminations of the veins are so 
 numerous, that it is impossible to include them in any general description ; it would seem 
 that, for the due performance of its function, it matters not whether a vein terminates in 
 one or another part of the venous system. It may be readily conceived that as the an- 
 astomoses of the veins are very numerous, and take place by very large branches, it can 
 be of little consequence which of those anastomotic branches predominates. 
 
 Terminaiion. 
 The veins of all the supra-diaphragmatic portion of the body terminate in the vena 
 cava superior ; the veins of the sub-diaphragmatic portion terminate in the vena cava 
 inferior ; the veins of the heart terminate separately in the auricle ; the two venae cavae 
 communicate with each other through the vena azygos, and especially through the veins 
 of the spinal canal, so that when either of them is obliterated the other supplies its place. 
 
 Valves. 
 
 The existence of membranous folds, or valves (a a. Jig. 218*), in the interior of the 
 veins is one of the most characteristic features in their structure. p^ 218 * 
 
 The existence of these valves is shown externally in injected veins 
 by a more or less distinct knotted appearance. 
 
 If we open, under water, a vein provided with valves, we perceive 
 attEiched to its interior surface certain membranous folds, or mem- 
 branous processes, as they were named by Charles Etienne, who 
 appears to have discovered them ; there are generally two, placed one 
 opposite the other ; they are rarely solitary even in the smallest ves- 
 sels, and still less commonly are three found together, as Haller and 
 Morgagni say they have observed. They all have a semilunar form, 
 like the sigmoid valves of the aorta and pulmonary artery ; their ad- 
 herent border is convex, and directed towards the extremities ; their 
 free border is straight, and is directed towards the heart. 
 
 Both surfaces are free ; the inferior is turned towards the centre 
 of the vessel, while the superior corresponds to its sides, which al- 
 ways present a dilatation or sinus (i) opposite the valves, that gives 
 a knotted appearance to the vein when distended ; the constricted 
 part of the vein corresponds to the adherent border of the valve, and 
 the dilated portion to the valve itself 
 
 As a necessary consequence of their direction, the valves permit the blood to flow 
 from the extremities towards the heart, but prevent its course in the opposite direction ; 
 it was this anatomical fact which led Harvey to the discovery of the course of the venous 
 
SW ANGEIOLOGY. 
 
 blood. The valves are so long, that when tvv'o opposite ones are depressed, they almost 
 completely close the channel of the vessel. 
 
 Notwithstanding their tenuity, the valves are extremely strong : a fact of which we 
 may be easily convinced by endeavouring to inject the veins in the opposite direction to 
 that in which the blood flows through them. The perforations and notches sometimes 
 observed in the valves of veins appear to me to be accidental. 
 
 The office of the valves is to prevent that retrograde movement in the course of the 
 blood which would otherwise occur from so many causes. 
 
 All veins are not provided with valves, and those which have them are very unequally 
 so. It may be said that their presence and their number, their proximity, and their dis- 
 tance from each other, are directly influenced by the degree of opposition to the onward 
 progress of the blood in any set of veins : thus, the v^ves are more numerous in the 
 veins of the limbs where the blood flows against its own gravity than in those parts 
 where it follows the direction of gravitation. There are no vedves in the system of the 
 vena portaj. They are generally more numerous in the deep than in the superficial veins. 
 
 We always find a pair of valves at the termination of a vein in a larger trunk. Very 
 small veins have no valves. I shall take care to describe the number and arrangement 
 of the valves in the principal veins. 
 
 The number of the valves is subject to many varieties. Some valves completely, and 
 others but imperfectly intercept the course of the blood. 
 
 Structure. 
 
 In structure, a vein appears to me to resemble an artery, without its middle coat.* In 
 fact, even by the most careful examination, we can only distinguish two coats in a vein ; 
 an external, called the cellular coat, but which I believe to be of the same nature as the 
 dartos, and an internal coat, very thin, which is analogous to the lining membrane of the 
 arteries, and, therefore, resembles the serous membranes. The internal membrane is 
 the essential constituent of a vein ; for the external coat may be wanting, or its place 
 may be supplied by some other tissue : thus, in the sinuses of the dura mater, in the cells 
 of the corpora cavernosa penis, in the substance of the walls of the uterus, and in the 
 venous canals of bones, the place of the external membrane is supplied by the dura mater, 
 by the fibrous parietes of the cells of the corpora cavernosa, by the tissue of the uterus 
 itself, and by the proper substance of the bones. 
 
 The valves are formed by a fold of the internal membrane, containing some fibrous 
 filaments, which are found especially along their adherent border. 
 
 The existence of a middle coat in the veins is admitted by authors, some of whom 
 say it is composed of longitudinal fibres, while others think it consists of circular fibres ; 
 but such fibres do not, in reality, exist. Vesalius relates that, wishing to show them at 
 one of his lectures, he was obliged to confess that he had never seen them, and could 
 not find them.t 
 
 The walls of the veins are themselves supplied with small arteries and veins {vasa, vaso- 
 rum). No nerves have been demonstrated in them, nor do either mechanical or chem- 
 ical stimuli applied to the inner membrane of the veins occasion pain. 
 
 It is rather a remarkable fact, in reference to the relations of the veins with the nerves, 
 that nervous plexuses are never supported by veins, but, on the contrary, seem always 
 to be separated from them. The trunk of the vena portas is the only exception. 
 
 Pr ^oration. 
 
 Most of the veins above a certain size may be examined without being previously in- 
 jected ; but injections are necessary for their minute investigation. The arrangement 
 of the valves, which, in general, oppose the transmission of liquids from the heart to- 
 wards the extremities, renders it necessary to inject a great number of veins from their 
 extremities towards the heart. In general, in order to obtain as perfect an injection as 
 possible, it is necessary to throw in the fluid simultaneously at several points and in sev- 
 eral directions. Thus, a pipe may be placed in the vena cava superior, into which the 
 injection should be pushed from the heart towards the extremities ; another in the upper 
 part of the cephalic or basilic vein of the right side ; a third in the dorsal vein of the left 
 thumb ; a fourth in the right femoral vein ; and, lastly, one in the left internal saphenous 
 vein. In all these vessels, excepting in the vena cava, the injection should be thrown 
 from the extremities towards the heart. 
 
 The injection of the veins from the arteries, which was proposed by Jankius, is doubly 
 
 ♦ [The walls of a vein are thinner than those of an artery ; and hence the former, when cut across, docs not 
 remain patent, like the latter kind of vessel. The coats of tlie superficial veins are thicker than those of the 
 deep-seated ones, especially in the lower limbs.] 
 
 t [Nevertheless, the veins have an intermediate set of fibres, constituting a thin middle coat. The external 
 coat is thinner than that of the arteries, and consists of interlaced cellular filaments. The middle coat, differ- 
 ing from that of an artery, is composed of pale red filaments, like those of cellular tissue, miied with others 
 resembling elastic tissue ; the bundles into which these filaments are collected pursue a very irregular course 
 around the vein. The internal coat is more distinct, less brittle, and more readily detached than the corre- 
 sponding- arterial tissue : it consists of fine longitudinal interlacing filaments, covered with an epithelium ; it 
 is continuous with the lining membrane of the auricles.] 
 
THE PULMONARY VEINS. 15*S^ 
 
 inconvenient ; first, because both veins and arteries would be coloured alike, which would 
 make it difficult to distinguish between them ; and, secondly, because we must use a 
 very thin liquid, which would not become firm. 
 
 The most convenient injection mass is a coloured glue-size, because it sets slowly. 
 If tallow be used, the subject must be placed in warm water. 
 
 The dissection of the veins, as well as that of the arteries, consists in separating them 
 from surrounding parts, and preserving their relations as much as possible. 
 
 Method of Description, 
 In describing the veins, we may either follow the course of the blood, ana trace the 
 veins from the extremities to the heart, or we may pursue an opposite direction, and 
 trace them from the heart to the extremities. I shall adopt a combination of the two 
 methods ; that is to say, I shall commence with the trunks, and pass in succession to 
 the larger and then to the smaller branches ; but in the particular description of each 
 vein, I shall consider it as originating at the point most remote from, and terminating at 
 the point nearest to, the heart. 
 
 DESCRIPTION OF THE VEINS. 
 
 THE PULMONARY VEINS. 
 Preparation. — Description. — Relations. — Size. — Peculianttes. 
 
 Preparation. — These veins may be traced from the heart towards their terminations 
 The facility with which injections pass from the pulmonary arteries into the pulmonary 
 veins should be borne in mind. 
 
 There are four pulmonary veins (I l,m m,fig. 171), two for each lung, which open sep- 
 arately into the left auricle. Not unfrequently, however, there are five ; three for the 
 right, and two for the left lung. Sometimes the two left puhnonary veins seem to unite 
 immediately before opening into this auricle. 
 
 The trunks of these veins, each of which corresponds to a lobe of the lung, pass out 
 of that organ in front of the corresponding pulmonary artery. The two upper veins of 
 the right lung generally unite into a single trunk, which descends towards the root of 
 the lung, while the inferior trunk runs horizontally. In the interior of each lobule, the 
 pulmonary veins coimnence from the ultimate ramifications of the pulmonary artery, and 
 unite into a single branch, which emerges from the lobule in contact with the corre- 
 sponding artery. These venous branches successively unite, so as to form a single 
 trunk for each lobe of the lung. There are, therefore, three trunks for the right lung 
 and two for the left ; but the trunk from the middle lobe of the right lung soon unites to 
 that from the upper lobe. The pulmonary trunk belonging to the upper lobe lies in front 
 of that belonging to the lower lobe ; it also passes obliquely downward and outward, 
 while that which belongs to the lower lobe runs horizontally. These four trunks open 
 into the four angles of the left auricle (n), after having perforated the pericardium, with- 
 in the cavity of which their course is exceedingly short. 
 
 Relations. — In the substance of the lungs the branches of the veins are behind, those 
 of the arteries are in front, and the bronchia are in the middle. The larger branches of 
 these three kinds of vessels cross each other at acute angles, but their extreme ramifi- 
 cations are parallel. At the root of the lung, the veins are in front, the artery is in the 
 middle, and the bronchus behind. 
 
 In the pericardium, the anterior surface of the veins is invested by the serous layer 
 of the pericardium. The right pulmonary veins are in relation, in front, with the vena 
 cava superior, which crosses them at right angles : the left puhnonary veins are in re 
 lation with the left pulmonary artery. 
 
 It is generally said that the pulmonary artery is larger than the pulmonary veins ; but 
 it has appeared to me that the pulmonary veins are no exception to the general rule that 
 the veins are larger than their corresponding arteries. 
 
 Moreover, although there are two pulmonary venous trunks for each lung, by a re- 
 markable exception only a single vein accompanies each branch of the artery. 
 
 The pulmonary veins have no valves, even at their openings into the auricle ; they 
 carry red blood like the arteries, and hence the name arteria. venosce, by which they were 
 designated by the ancients. Distinctly circular muscular fibres can be traced upon the 
 portion of the pulmonary veins situated within the pericardium. The serous layer only 
 partially invests these veins, and it is doubtful whether the fibrous layer is prolonged. 
 upon them at all. 
 
 THE VEINS OF THE HEART. 
 
 The Great Coronary or Cardiac Vein. — The Small Cardiac Veins. 
 The cardiac veins are divided into the great coronary vein and the small coronary 
 veins of the heart. 
 
 4D 
 
S78 ANGEIOLOGY. 
 
 The great coronary vein commences near the apex of the heart, at the lower part of 
 the anterior inter-ventricular furrow, up which it runs (e, fig. 191), gradually increasing 
 in size ; having arrived at the base of the ventricle, it turns to the left, so as to leave the 
 anterior coronary artery, and, changing its direction, it runs along the left auriculo- ven- 
 tricular furrow, becoming larger as it proceeds, and at length opens (e,fig. 192) into the 
 posterior and inferior part of the right auricle, near the inter-auricular septum. 
 
 The very great size of that portion of the vein which embraces the left auriculo-ven- 
 tricular furrow has obtained for it the name of the coronary venous sinus. It almost always 
 presents a very remarkable dilatation, or ampulla, before it enters the auricle. During 
 its course it receives a great number of branches. 
 
 Thus, its vertical or ascending portion receives both superficial and deep veins, which 
 emerge from the adjacent parts of the ventricles and their intervening septum. 
 
 Its circular portion receives some small descending or auricular branches from the left 
 auricle, and also larger ascending or ventricular branches, which enter it at right angles ; 
 among the latter, we find the vein of the left border of the heart, which commences near 
 the apex of the left ventricle, runs backward, crossing obliquely over the corresponding 
 artery, and opens, almost at a right angle, into the great coronary vein, behind the left 
 border of the heart ; secondly, two or three branches from the posterior surface of the 
 left ventricle ; and, lastly, a posterior inter-ventricular branch, which traverses the poste- 
 rior inter-ventricular furrow, and terminates in the ampulla, at the opening of the coro- 
 nary vein into the right auricle. I have seen this branch terminate at once in the auri- 
 cle by a distinct opening, covered or protected by the valve of the coronary vein. A 
 small vein which runs along the posterior half of the right auriculo-ventricular furrow 
 opens directly into the right auricle, near the ampulla of the great coronary vein : I do 
 not know whether this small vein is constant. The great coronary vein has no valves, 
 excepting at its entrance into the right auricle, where the valve, however, cannot 
 completely oppose the reflux of the blood, for the great coronary vein is always filled 
 when an injection is thrown into the vena cava superior. 
 
 The small or anterior coronary veins of the heart, or small cardiac veins {vence innomi- 
 nate of Vieussens), consist of three or four small veins, which run upon the anterior 
 surface of the right ventricle, and open at the lower part of the right auricle. Among 
 them we may point out one which runs along the right border of the heart, and has been 
 CEdled the vein of Galen ; and also another very small one, which commences upon the 
 infundibuliform prolongation of the right ventricle, enters the right auriculo-ventricular 
 furrow, and opens directly into the right auricle. 
 
 It follows, then, that the small cardiac veins belong to the front of the right ventricle 
 and auricle, or, we might even say, to the greater part of the right side of the heart; 
 while the great coronary vein belongs to the left side of the heart, and to the remaining 
 part of the right side. 
 
 I have already said that the veins of Thebesius, or vena minima, which are described 
 by Vieussens, Thebesius, and Lancisi, and which are said to pour their contents into all 
 the cavities of the heart, do not exist at aU, and that their supposed orifices are nothing 
 more than culs-de-sac, formed by intervals between the muscular fasciculi of the heart, 
 and at the bottom of which an areolar structure is seen. I agree with Senac in admit- 
 ting the existence of venous openings in the right auricle only (of course excepting those 
 of the pulmonary veins) 
 
 THE SUPERIOR, OR DESCENDING VENA CAVA AND ITS BRANCHES. 
 
 The Superior Vena Cava. — The Brachio-cephalic Veins — the Inferior Thyroid — the Internal 
 Mammary — the Superior Phrenic, the Thymic, Pericardiac, and Mediastinal — the Verte- 
 bral. — The Jugular Veins, viz., the External — the Anterior — and the Internal. — The En- 
 cephalic Veins, and the Sinuses of the Dura Mater, viz., the Lateral — the Superior Lon- 
 gitudinal — the Straight — the Superior and Inferior Petiosal — the Cavernous — the Coro- 
 nary — and the Anterior and Posterior Occipital Sinuses — the Conflux of the Sinuses. — 
 jyie Branches of Origin of the Jugular Veins — the Facial — the Temporo-maxillary — the 
 Posterior Auricular — the Occipital — the Lingual — the Pharyngeal — the Superior and Mid- 
 dle Thyroid — the Veins of the Diplo'e. — Summary of the Distribution of the Veins of the 
 Head. — The Deep Veins of the Upper Extremity — the Palmar, Radial, Ulnar, Brachial, 
 and Axillary — the Sub-clavian. — The Superficial Veins of the Upper Extremity — in the 
 Hand — in the Forearm — at the Elbow — aiid in the Arm. — General Remarks en these Su- 
 perficial Veins. 
 
 The vena cava superior, descenden^, is the common trunk of all the veins of the upper 
 naif of the body, and very nearly corresponds to the ascending aorta in the parts to 
 which it is distributed. It is situated to the right of the sternum, within the thorax, and 
 hence has been named the thoracic vena cava ; it commences immediately below the car- 
 tilage of the first rib on the right side, where it is formed by the junction of the two 
 brachio-cephahc veins (c c', fig. 1 701. which return the blood from the whole supra-dia* 
 
679 
 
 pbragmatic portion of the body : from the point above mentioned it descends vertically, 
 describing a slight curve, the concavity of which is turned to the left, and the convexity ■ 
 to the right side ; it enters the pericardium, and (d,figs. 191, 193) opens into the upper 
 part of the right auricle (m h, Jig. 193) behind the auricula ; its posterior half appears to 
 be continuous with the corresponding part of the vena cava inferior: hence, doubtless, 
 arose the opinion of Vesalius, that there is but one vena cava. 
 
 Its relations, while without and within the pericardium, require to be separately ex- 
 amined. Externally to the pericardium, the vena cava superior is in relation with the 
 right lung, being separated from it, however, by the right wall of the mediastinum, and 
 by the phrenic nerve, which is at first on the outer side, and then passes in front of the 
 vein ; on the left side, it is in relation with the arch of the aorta ; in front, with the re- 
 mains of the thymus gland and the cellular tissue of the mediastinum, by which it is 
 separated from the sternum ; behind, with the trachea, a great number of lymphatic 
 glands intervening between them. 
 
 Within the pericardium the vena cava is covered by the serous layer of that membrane 
 in its anterior three fourths : it is in immediate contact behind with the right pulmonary 
 artery and right superior pulmonary vein ; on the left side, it is merely in contact with 
 the aorta. 
 
 The superior vena cava has no valves, either in its course or at its opening : it follows, 
 therefore, that each contraction of the auricle is accompanied by a regurgitation of blood 
 into the vena cava and into the branches immediately opening into it. Upon this regm- 
 gitation depends the phenomenon of venous pulsation. 
 
 The vena cava presents certain conditions in its structure which require special notice. 
 It has been said that the muscular fibres of the auricle are prolonged upon it ; I can state 
 that such is not the case. The serous layer of the pericardium covers the pericardial 
 portion of this vein, and the fibrous layer is prolonged upon that part of the vessel which 
 is external to the pericardium. 
 
 Lastly, the relative length of the intra- and extra-pericardial portions of the vena cava 
 is subject to much variety : sometimes the vein enters the pericardium at about the mid- 
 dle of its course ; sometimes only a few lines from its termination in the auricle. 
 
 The caliber of the vena cava superior is less than that of both the brachio-cephalic 
 trunks taken together, and also less than that of the vena cava inferior. Its length va- 
 ries from two and a half to three inches. 
 
 Sometimes this vein is double : I once found in an adult two superior cavae, opening 
 into the right auricle, a variety which evidently depended upon the two brachio-cephalic 
 veins not having united. This condition is normal in several animals. 
 
 Collateral Veins. — The vena cava superior receives no branch while within the pericar- 
 dium, immediately before entering which it receives the vena, azygos. The right inferior 
 thyroid and internal mammary veins, and the small veins called thymic, pericardiac, medias- 
 tinal, and right superior phrenic, generally enter opposite the junction of the two brachio- 
 cephalic trunks, and not into the vena cava itself 
 
 As the vena azygos forms part of the system of spinal veins, it will be described with 
 them. 
 
 As the other veins have a similar distribution on both sides, the description of those 
 on the left side will apply to those of the right also. 
 
 The Brachio-cephalic Veins. 
 
 The brachio-cephalic veins, or vencE innominatts of Meckel {cc',jig. 170), which are gen- 
 erally included in the description of the sub-clavian vein, correspond exactly to the bra- 
 chio-cephalic or innominate artery, being fonned by the union of the internal jugular 
 vein {d) and the sub-clavian vein (e), properly so called, which correspond to the common 
 carotid and the sub-clavian arteries. 
 
 There are two brachio-cephalic veins, one for the right (c') and one for the left side 
 (c) ; so that the arrangement of the veins of the upper half of the body is more sym- 
 metrical than that of the arteries. 
 
 The right and left venous trunks differ from each other in length ; for as they both 
 commence at the junction of the corresponding internal jugular and sub-clavian veins, 
 opposite the sternal end of the clavicle of their own side, and terminate on the right of 
 the median hue, to form the commencement of the vena cava superior, it follows, therefore, 
 that the right brachio-cephalic vein must be much the shorter ; it is, in fact, only from 
 twelve to fourteen lines in length, while that of the left side is twice as long. 
 
 They differ also in caliber, the left brachio-cephahc trunk being much larger than the 
 right, in consequence of receiving the internal mammary and inferior thyroid veins of its 
 own side. 
 
 Also in direction, the right being almost vertical, and sloping only slightly to the left 
 side as it descends, like the superior vena cava, which follows the very same direction ; 
 the left vein, on the contrary, is almost horizontal, and describes a curve with its con- 
 cavity directed backward ; the two brachio-cephahc veins, therefore, unite at a right 
 angle to form the vena cava. 
 
580 ANGEIOLOGY. 
 
 Lastly, they have different relations. Tlie concavity of the left vein embraces the 
 front of the highest part of the aortic arch, and the three great arteries arising from it. 
 It coiTesponds anteriorly veith the sternal extremity of the left clavicle and the sterno- 
 clavicular articulation, and runs along the upper border of the sternum. The right vein 
 is situated in the right cavity of the thorax ; it is parallel with, and on the outer side of, 
 the brachio-cephalic artery, and it is in contact behind and on the right side with the right 
 wall of the mediastinum and with the pneumogastric nerve, which are interposed be- 
 tween it and the apex of the lung. 
 
 The relations of the left brachio-cephalic vein with the arch of the aorta account for 
 its obliteration in aneurism of that vessel, and its relation to the upper part of the ster- 
 num explains the venous pulse, seen so distinctly opposite the fourchette of the sternum 
 in severe attacks of dyspnoea. 
 
 There are no valves in the interior of these veins, and hence considerable regurgita- 
 tion may occur. 
 
 Collateral Branches. — The right brachio-cephalic vein, in some cases, receives only the 
 vertebral brain ; but most commonly the right inferior thyroid and right internal mam- 
 mary veins terminate in it. The left brachio-cephalic vein always receives the above- 
 mentioned veins of its own side, and also the superior phrenic, the thymic, and pericardiac 
 veins, and often the superior intercostal vein. As this last forms part of the system of the 
 vena azygos, it will be described in another place. 
 
 The Inferior Thyroid Veins. 
 
 There are two o tnese, viz., a right and a left inferior thyroid vein : not unfrequently 
 there are three, and even four. 
 
 The course of the inferior thyroid veins corresponds exactly with that of the inferior 
 thyroid artery of Neubauer, when it exists. They arise from the thyroid venous plex- 
 uses, and sometimes directly from the superior thyroid vein by an anastomotic arch ; 
 they descend vertically between the trachea and the muscles of the sub-hyoid region, 
 and terminate differently on the right and left sides, the right inferior thyroid vein ter- 
 minating at the junction of the two brachio-cephalic veins, and sometimes even in the 
 upper and anterior part of the superior vena cava, while the vein of the left side enters 
 the corresponding brachio-cephalic vein. 
 
 In one case in which there were thi-ee inferior thyroid veins, the middle one ended in 
 the superior cava, and the two lateral veins in the corresponding brachio-cephalic trunks. 
 
 These veins, moreover, present innmnerable varieties in their number, course, anas- 
 tomoses, and termination. One of the most curious and frequent of these varieties is 
 that in which the right and left veins form an arch, which receives four or five parallel 
 branches that issue from the thyroid gland. 
 
 The inferior thyroid veins are joined by the tracheal and inferior laryngeal veins, so 
 that Winslow named them guttural or tracheal. They form, in front of the trachea, a 
 large plexus, which it is impossible to avoid in performing tracheotomy. 
 
 The Internal Mammary Veins. 
 
 The internal mammary veins follow the same course as the arteries of that name, and 
 receive a series of branches corresponding to those given off by the arteries, excepting 
 in one instance, viz., the superior phrenic veins, neither of which, in general, terminates 
 in the corresponding internal mammary. 
 
 Usually, there are two veins of unequal size for each internal mammary artery, which 
 is placed between them. The two almost always unite into a single trunk, which ter- 
 minates on the right side at the junction of the two brachio-cephalic veins, or in the up- 
 per and front part of the superior cava, and on the left in the corresponding brachio- 
 cephalic vein. 
 
 Among the veins which open into the internal mammary, I should mention the proper 
 veins of the sternum, which form a very remarkable venous network in front of and be- 
 hind each piece of that bone beneath the periosteum. 
 
 The Superior Phrenic, and the Thymic, Pericardiac, and Mediastinal Veins. 
 
 These are small veins which unite into two groups, one for the right side, terminating 
 at the junction of the two brachio-cephalic veins, or at the upper and anterior part of the 
 superior vena cava ; the other for the left, and teraiinating in the left brachio-cephalic 
 veni. The pericardiac and mediastinal veins commence upon the pericardium and the 
 anterior mediastinum. 
 
 The thymic veins, which are very large in the fcetus, may still be seen in the adult and 
 the aged, for the th)nnus gland is never completely absorbed. 
 
 The superior phrenic veins are remarkable for their length as well as for their small 
 size ; they accompany the phrenic nerve and the superior phrenic arteiy : the left supe- 
 rior phrenic vein often enters the corresponding superior intercostal vein, and frequent- 
 ly the internal mammary vein 
 
THE JUGULAR VEINS. 
 
 Fig. 219. 
 
 The Vertebral Veins. 
 
 The vertebral vein corresponds to the cervical portion of the artery of the same name, 
 and, like it, is contained in the canal formed by the series of foramina at the base of the 
 transverse processes of the cervical vertebra ; it opens into the braehio-cephalic vein im- 
 mediately behind the internal jugular ; and it is said to open occasionally into the last- 
 mentioned vein. Not unfrequently, as Eustachius remarks, this vein divides into two 
 branches near its termination, one of which emerges with the artery, between the fifth 
 and sixth vertebrae, while the other, either alone or accompanied by a small arterial twig, 
 escapes by the foramen of the seventh cervical vertebra. I have seen these two branch- 
 es emerge, one at the foramen of the fifth, the other at that of the sixth cervical vertebra. 
 
 This vein commences in the deep muscles at the back of the neck, communicates by 
 a large branch with the occipital vein, and sometimes receives a small branch, which 
 passes out at the posterior condyloid foramen ; it enters the canal of the transverse pro- 
 cesses, between the occipital bone and the atlas ; and while within this canal, it receives 
 anterior muscular branches from the praevertebral region, posterior branches from the 
 external spinal veins, and vertebro-spinal branches from the interior of the spinal canal. 
 At the point where it opens into the braehio-cephalic vein, it receives a large branch, 
 which corresponds in its course to the ascending cervical artery ; it also receives the 
 deep cervical vein, which has the same distribution as the artery of that name. 
 
 The Jugular Veins. 
 The jugular veins (from jugulum, the throat) are three in number on each side, viz., 
 the internal or deep jugular {n,Jig. 219), the external jugular (A), and the anterior jugular 
 (m). The two latter veins form part of the superficial or sub-cutaneous venous system ; 
 but the internal jugular is the satellite vein of the common carotid artery and its branch- 
 es. I shall describe these three veins in succession, but shall not notice the veins with 
 which they are directly continuous, nor yet their branches of origin, until I have described 
 all three of them, because those branches terminate almost indifferently in either of them. 
 
 The External Jugular Vein. 
 
 The external jugular (h), one of the supplementary veins of the internal jugular, is a 
 6ub-cutaneous vein of the neck, on the lateral and 
 anterior aspect of which it is situated. It is bound- 
 ed above by the angle of the lower jaw according to 
 some authors, by the neck of the condyle of that bone 
 according to others : the former mode of limitation 
 seems to me to be preferable. It is bounded below 
 by the clavicle, behind which it ends in the sub-cla- 
 vian vein (o), immediately to the outer side of the 
 internal jugular, and sometimes even opposite that 
 vein, but upon a plane anterior to it. 
 
 The external jugular is generally single, but is 
 sometimes double ; and this depends either upon 
 some of its branches of origin not joining it until 
 they reach the lower part of the neck, or else upon 
 the existence of a small collateral branch, which ari- 
 ses from the upper part of the external jugular, runs 
 along its outer side, and opens into it below, imme- 
 diately before its termination ; at other times the 
 external jugular bifurcates before it ends in the sub- 
 clavian. 
 
 The external jugular varies extremely in size, 
 which frequently differs on the two sides, and is not 
 uniform throughout its whole length. Thus, it al- 
 most always presents an ampulla, or ovoid dilatation 
 of variable dimensions, near its termination. In size 
 it is inversely as that of the other jugular veins of the same and the opposite side, and 
 its differences are either congenital or acquired ; the former depending upon the fact of 
 its receiving more or fewer branches, while acquired alterations in size are occasioned 
 either by some occupation requiring violent respiratory efforts, or by the venous circula- 
 tion being impeded by disease. 
 
 Direction.. — The external jugular vein passes obliquely downward and backward in the 
 opposite direction to the sterno-cleido-mastoideus, which it crosses at a very acute an- 
 gle, and then runs parallel to the posterior border of that muscle. A line drawn from 
 the angle of the jaw to the middle of the clavicle will exactly indicate its direction. Op- 
 posite the clavicle, the external jugular vein turns forward and opens into the sub-clavi- 
 an, either directly, or after running horizontally for some lines. 
 
 Relations. — The external jugular vein runs first across the stemo-mastoid, and then 
 the supra- clavicular region of the neck. In the whole of its extent it is covered and 
 
582 ANGEIOLOGY. 
 
 separated from the skin by the platysma ; hence the rule to open this vein across the 
 fibres of the platysma, when it is desirable that the orifice should be free, and favourably 
 disposed for the flow of blood. By its deeji surface it is in relation with the stemo- 
 mastoid, which it crosses obliquely, so that it rests above upon the anterior border of 
 that muscle, and below upon its external surface, and parallel with its outer border. 
 In the supra-clavicular region it is in relation behind with the omo-hyoid and scalenus 
 anticus muscles and with the brachial plexus. It is always separated from these differ- 
 ent parts by the cervical fascia, which is perforated by it as it curves forward to entei 
 the sub-clavian vein. 
 
 The external jugular vein is surrounded by the superficial nerves of the cervical plex- 
 us, some of which pass in front, and others behind it. The auricular nerve runs behind 
 its upper portion. 
 
 This vein has generally two valves, one in the middle, the other near its termination ; 
 sometimes only the latter exists. These valves do not appear, in general, to oppose any 
 great obstacle to an injection thrown from the heart towards the extremity of the vein. 
 
 Collateral Branches. — The external jugular vein receives, in front, branches of variable 
 size and number, which communicate with the anterior jugular vein, and others which 
 pass directly out of the sterno-mastoid muscle ; behind, it receives the superficial occip- 
 ital veins (k), and several superficial branches from the posterior and lateral regions of the 
 neck ; lower down, it also receives the supra-scapular and posterior scapular veins (1), 
 which exactly correspond to the arteries of the same names. A constant branch passes 
 beneath the clavicle, and establishes a communication between the external jugular vein 
 and the upper part of the veins of the arm. 
 
 Branches of Origin. — These are extremely variable ; most commonly the external jug- 
 ular is formed by the junction of the temporal (/) and the internal maxillary veins. Some- 
 times it is formed by a branch resulting from the bifurcation of a trunk common to those 
 two veins ; at other times, by the successive juction of the temporal, internal maxillary, 
 facial, lingual, and superior laryngeal veins. 
 
 In all cases the external communicates either directly or indirectly with the internal 
 jugular vein in the substance of the parotid gland by means of a communicating branch, 
 which may be regarded as a branch of origin, and which sometimes is the only branch of 
 origin. 
 
 The interior Jttgular Vein. 
 
 The anterior jugular is a sub-cutaneous vein {m,fig. 219), supplementary to the exter- 
 nal and even to the internal jugular, and collects the blood from the parts situated in the 
 middle of the anterior region of the neck. 
 
 It varies in size in different individuals, is almost always inversely proportioned to the 
 external jugular, and is often larger than that vein. We frequently find both a right and 
 a left anterior jugular vein ; but then they are rarely of equal size. Rather frequently, 
 however, there is only one, scarcely a trace of the other existing. Lastly, instead of 
 these veins, there are occasionally only some small branches, which scarcely deserve 
 notice. 
 
 Direction. — From the supra-hyoid region, where it commences, this vein passes verti- 
 cally downward, between the median line and the inner border of the sterno-mastoid mus- 
 cle ; opposite the fourchette of the sternum it bends abruptly, passes horizontally out- 
 ward behind the two lower fasciculi of the sterno-mastoid, and enters the sub-clavian 
 vein on the inner side of the external jugular, sometimes opposite to, but in front of the 
 internal jugular ; lastly, in other cases, it terminates by a common orifice with the ex 
 temal jugular. 
 
 During its course it runs in the substance of that median layer of fibrous tissue which 
 we have called the cervical linea alba, and it receives several collateral branches. 
 
 Collateral Branches. — The anterior jugular veins communicate with the external by 
 one or two branches of variable size ; they also communicate freely with the internal 
 jugular veins ; the communicating branches often form the origins of this vein. The an- 
 terior jugular receives some laryngeal branches, and sometimes an inferior thyroid vein. At 
 the point where it bends at the lower part of the neck it receives a sub-cutaneous vein, 
 which comes from the upper part of the thorax, and passes above the fourchette of the 
 stemiun. At the same point, also, the right and left anterior jugular veins communicate 
 with each other by a transverse branch {r,fig. 223), into which branches derived from 
 the inferior thyroid vein, or even some branches communicating directly with the left 
 brachio-cephalic vein, pour their contents. 
 
 Branches of Origin. — The anterior jugular vein often commences by sub-cutaneous 
 and muscular branches, derived from the supra-hyoid region, and corresponding in their 
 several courses to the branches of the sub-mental artery. I have seen it arise from one 
 end of a loop, the other end of which was continuous with the external jugular vein ; at 
 other times it commences by a common trunk with the facial and lingual veins. Lastly, 
 I have seen the anterior jugular form the continuation of the facial vein. 
 
THE INTERNAL JUGULAR VEIN, ETC. 
 
 The Internal Jugular Vein. 
 
 The internal jugular vein (n,fig. 219), the principal vein of the head, collects the blood 
 from the interior of the cranium and from the greater part of the face and neck ; it com- 
 mences at the posterior lacerated foramen, and terminates in the brachio-cephalic vein 
 (r), which is formed by the junction of the internal jugular with the sub-clavian vein (o). 
 Its direction is vertical, without any deviation or bending. 
 
 It is of considerable size, but varies in different individuals ; it is seldom of equal size 
 on both sides, and is inversely proportioned to the external and anterior jugular veins ; 
 it becomes extremely large in such chronic diseases as impede the entrance of blood 
 into the cavities of the heart. I have sometimes seen the internal jugular vein of the 
 left side very small, its place being then supplied, as in the lower animals, by a very large 
 external jugular. 
 
 Moreover, the internal jugular is not of uniform size throughout its whole length. It 
 commences at the posterior lacerated foramen by a dilatation, which is called the gulf of 
 the internal jugular vein ; it continues of the same size until opposite the larynx, where 
 it becomes greatly enlarged in consequence of receiving several branches ; it terminates 
 below in an oblong dilatation, and is again slightly contracted as it opens into the brachio- 
 cephalic vein. This oblong dilatation in some asthmatic persons is very large, and might 
 be called the sinus of the internal jugular vein. 
 
 That part of the internal jugular vein which extends from the os hyoides to the brachio- 
 cephalic vein represents the common carotid artery ; the part included between the os 
 hyoides and the posterior lacerated foramen represents the internal carotid ; and the se- 
 ries of branches which terminate in it represent the external carotid and the ramifica- 
 tions of that artery. These branches of the internal jugular, however, do not unite into 
 a common trunk corresponding to the trunk of the external carotid arteiy, so that the 
 distribution of this vein represents very nearly that variety in the distribution of the ar- 
 teries of the neck, in which there is no external carotid artery ; the branches usually 
 given from it arising from the common carotid artery, which then terminates in the in- 
 ternal carotid. 
 
 Relations. — In that portion of its course which corresponds to the internal carotid ar- 
 tery, the internal jugular vein has almost the same relations as that vessel : thus, it is 
 situated in the triangular interval between the pharynx and the ramus of the lower jaw ; 
 the artery, together with the pneumogastric, hypo-glossal, glosso-pharyngeal, and spinal 
 accessory nerves, lie to the irmer side and in front of it ; the styloid and vaginal pro- 
 cesses, and the styloid muscles, are also anterior to the internal jugular vein. That por- 
 tion of the vein which represents the common carotid artery lies on the outer side of 
 that vessel and in contact with it, excepting below, where the carotid is directed some- 
 what inward to reach the arch of the aorta, while the vein continues to be vertical, and 
 is therefore separated from the artery. During its course it has the same relations as 
 the artery, only on account of being situated to the outer side of that vessel, it follows 
 that it is not covered by the platysma myoides to so great an extent as the artery, and, 
 therefore, that it is covered for a greater length by the stemo-mastoid ; and, indeed, its 
 lower end is inclined to project beyond the outer border of that muscle, so that in asth- 
 matic persons the skin covering the anterior part of the supra-clavicular triangle be- 
 comes elevated when the enlarged part of the vein is dilated. The pneumogastric nerve 
 is situated behind, between the artery and the vein. A very important relation of the 
 internal jugular vein is that which it has with the sub-clavian artery, which is situated 
 between it and the vertebral vein, the internal jugular being in front, and the vertebral 
 vein behind the artery. 
 
 The internal jugular vein returns all the blood from the interior of the cranium, re- 
 ceiving it from the lateral sinus, which may be regarded as the origin of this vein, and 
 as the common trunk of all the veins within the cranium. Its collateral branches, several 
 of which belong sometimes to the internal, and at others to the external jugular, are the 
 facial (c), lingual, inferior pharyngeal, superior thyroid (all which open by a common trunk), 
 and middle thyroid veins, sometimes also the temporal (f), internal maxillary, and deep oc- 
 cipital veins. "We shall describe in succession the branches of origin, and then the col- 
 lateral branches of the internal jugular vein. 
 
 The Encephalic Veins and thb Sinuses of the Dura Mater. 
 
 The commencing twigs and the branches of the cerebral veins are like all other veins, 
 but their trunks are essentially different, for they consist of fibrous canals, formed, as it 
 were, in the substance of the dura mater ; the lining membrane of these canals is the 
 only part in which they correspond in structure with the rest of the venous system, the 
 dura mater forming their outer coat. These canals are called the sinuses of the dura 
 mater. They receive the blood from the brain, cerebellum, and medulla, from the eye. 
 and from the bones of the cranium. 
 
 All the sinuses of the dura mater have a similar situation ; they all occupy grooves form- 
 ed for them upon the internal surface of the bones of the cranium, and which we have 
 already described. They are, for the most part, situated opposite the intervals between 
 
ANGEIOLOGY. 
 
 the great divisions of the encephalon : thus, the superior longitudinal sinus occupies the 
 fissure between the two hemispheres of the brain ; the lateral sinuses are situated op- 
 posite the great fissure which separates the cerebrum from, the cerebellum. All the 
 sinuses communicate with each other, and form an uninterrupted series of canals ; they 
 all open into the later£il sinuses, which are to the other sinuses what venous trunks are 
 to their branches. 
 
 There are twelve sinuses in all, not including the inferior longitudinal sinus, which may- 
 be regarded as a vein. Eight of the sinuses exist in pairs, the remaining four are sin- 
 gle, and occupy the median line. The single sinuses are the superior longitudinal sinus, 
 the straight sinus, the coronary sinus, and the transverse occipital sinuses. The eight 
 sinuses which exist in pairs are placed four on each side of the cranium ; they are the 
 two superior and two inferior petrosal, the two occipital, and the two lateral sinuses. 
 
 As the lateral sinuses form, as it were, the common trunks of all the others, I shall 
 oescribe them first. 
 
 The Lateral Sinuses. 
 
 The lateral or transverse sinuses (a a. Jig. 221) are situated in the lateral grooves {vide 
 Osteology, p. 80) ; each of them commences, like those grooves, at the internal occip- 
 ital protuberance, and passes horizontally outward as far as the base of the petrous por- 
 tion of the corresponding temporal bone, at which point it dips obliquely downward 
 and inward into the inferior occipital fossa, turns round the base of the pars petrosa, and 
 again ascends to reach the posterior lacerated foramen of its own side (s s,fig. 221), 
 where it terminates in the internal jugular vein. Like the corresponding grooves, the 
 right and left lateral sinuses are of unequal size, the right being almost always the lar- 
 ger. Both of them gradually increase in size from their posterior extremity, which may 
 be regarded as their origin, to their anterior extremity. 
 
 A section of the horizontal portion of each lateral sinus, which is situated in the outer 
 margin of the tentorium cerebelli, is triangular, while that of its vertical or curved por- 
 tion is semi-cylindrical. In the first part of its course it projects beyond the correspond- 
 ing groove in the occipital bone, so as to occupy the fissure between the cerebrum and 
 cerebellum. In the remamder of its course it does not project into the interior of the 
 cranium, or pass beyond the groove, which is exactly suited to its dimensions. 
 
 The internal surface of each lateral sinus is smooth, and it is not traversed by bands 
 like those found in the other sinuses. However, I once found in the horizontal portion 
 of this sinus some of the white bodies called glandulse Pacchioni. 
 
 One of the lateral sinuses has been found divided, in front, into two equal parts, a su- 
 perior and inferior, by a perfect horizontal septum ; it is very common to find a fibrous 
 lamina indicating a trace of this subdivision. 
 
 The anterior extremity of each lateral sinus is continuous with the gulf of the corre- 
 sponding internal jugular vein, and the inferior petrosal sinus of its own side opens into 
 it at the same point. During its course it receives some inferior cerebral veiris, some cere- 
 bellar veins, and the superior petrosal sinus (/), which enters it at the point where it chan- 
 ges its direction from horizontal to oblique, i. e., opposite the base of the petrous portion 
 of the temporal bone. 
 
 The lateral and inferior cerebral veins commence partly on the lateral and inferior parts 
 of the convex surface of the. cerebrum, and partly on the base of the brain ; they unite 
 so as to form a group of three, four, or five veins, which open into the horizontal por- 
 tion of the lateral sinus. They enter from before backward, that is to say, in an oppo- 
 site direction to the course of the blood in the sinus. One of these veins is sometimes 
 observed to run along the tentorium cerebelli, with which it is maintained in contact by 
 the parietal layer of the arachnoid for about an inch before it opens into the lateral sinus 
 
 The lateral and inferior cerebellar veins are very large ; they commence upon the lower 
 surface of the cerebellum, and terminate in two or three trunks, which are found upon 
 the circumference of the cerebellum, and open into the horizontal portion of the lateral 
 sinus by perforating its lower wall. 
 
 A large mastoid vein, which may be regarded as one of the principal origins of the oc- 
 cipital, also opens into the lateral sinus, and thus establishes a free and direct commu- 
 nication between the venous system within and that outside the cranium. 
 
 The Superior Longitudinal Sinus. 
 
 The superior longitudinal sinus {b b,fig. 220) is a single and median sinus, which occu- 
 pies the longitudinal groove, and accordingly extends from the crista galli to the inter- 
 nal occipital protuberance ; it is formed within the substance of the convex border of the 
 falx cerebri, and is three-sided; a section of it represents an isosceles triangle {I, Jig. 
 221), with its base turned upward and its apex downward. It is small at its anterior 
 extremity, but gradually increases in size as it approaches the confluence of the sinuses 
 («, Jig. 221), in which it terminates. It not unfrequently bifurcates near its posterior ex- 
 tremity ; sometimes it is directly continuous with the right lateral sinus. 
 
 The internal surface of this sinus is remarkable for the transverse bands found in it. 
 
THE SUPERIOR LONGITUDINAL SINUS, ETC. 6S5 
 
 especially along its inferior angle. These bands Fi^. S20. 
 
 consist of fibrous tissue covered by the lining mem- 
 brane of the sinus, and they conceal the orifices 
 of the veins which open into it ; in some points 
 they are so numerous as to form an areolar tissue. 
 Lastly, we ahnost always find on the internal sur- 
 face of the sinus some small white projecting bod- 
 ies, the glandulce Pacchioni. 
 
 The following veins open into the superior lon- 
 gitudinal sinus : some from the internal or flat sur- 
 face of each cerebral hemisphere, called the inter- 
 nal cerebral veins ; others from the upper half of the 
 convex surface of the brain, or the external cere- 
 bral ; and, lastly, several veins from the dura mater 
 and the bones of the cranium. 
 
 The internal cerebral veins, three or four in number on each side, return the blood from 
 all the convolutions of the flat surface of the corresponding hemisphere of the brain, and 
 enter the superior cerebral veins at the point where these are applied to the surface of 
 the falx. 
 
 The superior cerebral veins vary in number, but are generally seven or eight on each side. 
 The anterior of these veins are very small ; the posterior are much larger. There is al- 
 most always one of greater size than the rest, which may be named the great superior 
 cerebral vein : it appears to commence in and run along the fissure of Sylvius, is then 
 prolonged obliquely backward, and turning forward upon the convex surface of the brain, 
 so as to describe a curve having its concavity directed forward, it becomes applied to 
 the falx cerebri, and opens into the longitudinal sinus, after having run for about one inch 
 in the substance of its walls. During its course this vein receives a great number of 
 branches, some anterior and others posterior, which, although corresponding to the arter- 
 ies in their origin and in a part of their course, are completely separated from those ves- 
 sels at their termination. The common trunks pass inward towards the great median 
 fissure of the brain ; near the sinus they become attached to the dura mater, being held 
 down by the arachnoid membrane, which is reflected from the brain upon the dura ma- 
 ter; they then change their direction, turn forward in the substance of the falx cerebri, 
 beneath a very thin layer of the dura mater, and after a course of from six to ten lines in 
 length, terminate in the longitudinal sinus by one or more openings. The manner in 
 which the cerebral veins open into the sinus varies : for some there are lateral openings, 
 as if made by a punch ; others open by means of an areola fibrous tissue, which, as I have 
 already stated, is found in certain parts of the walls of the sinuses. All the venous ori- 
 fices are concealed by fibrous areolae, none of the veins opening directly into the sinus. 
 Most of them run for a certain distance from behind forward, i. e., in an opposite direction 
 to the course of the blood, before they open into the sinus ; the most anterior veins, 
 which run from before backward, are the only exceptions to this rule. Moreover, the fold 
 or bands which are formed in this and other sinuses do not perform the functions of 
 valves, for they permit fluids to pass from the sinus into the veins. The inferences drawn 
 by physiologists from the direction in which the cerebral veins open into the sinuses ap- 
 pear to me to be erroneous, for that direction facilitates instead of opposing the reflux 
 of the blood. I have satisfied myself that the cerebral veins have no valves in any part 
 of their extent. 
 
 The superior longitudinal sinus also receives proper veins from the dura mater, some 
 venous or diploic veins, and several veins which conmience in the pericranium, and es- 
 tablish a communication between the external and internal veins of the cranium. Among 
 the communicating veins are those which traverse the parietal foramina, and are called 
 the veins of Santorini. A very great number of veins penetrate through the longitudinal 
 suture, to open into the corresponding sinus in young subjects ; the communication of the 
 diploic veins with those of the dura mater, and with the sinuses and cerebral veins, may 
 be shown by perforating with a pin, in a young subject, the very thin and brittle external 
 bony table which covers one of the numerous veins of the diploe, and then inserting into 
 the orifice the fine point of a mercurial injecting apparatus : the mercury will fill the diplo- 
 ic veins, and will pass into the sinuses, the veins of the dura mater, and the cerebral veins 
 
 The Straight Sinus. 
 
 The straight sinus (,c,Jig. 220) occupies the base of the falx cerebri, corresponding with 
 the line of junction of the falx with the tentorium cerebelli. 
 
 The straight sinus is therefore single, and situated in the median line ; it is directed 
 somewhat obliquely backward and downward, and it opens into the confluence of the si- 
 nuses or torcular Herophili (n), by one or sometimes two orifices, according to the pres- 
 ence or absence of a vertical band across its termination. It is three-sided, and a sec- 
 tion of it represents an isosceles triangle {c,fig. 221), having its base turned downward. 
 
 This sinus increases in size as it proceeds backward. 
 
 4 £ 
 
<S86 ANGEIOLOGY. 
 
 The straight sinus receives by its anterior extremity the inferior loTigitudinal vein or 
 sinus, the two great vc7itricular veins or vena Galeni, the inferior median cerebral veins, and 
 the superior median cerebellar vein. 
 
 The inferior longitudinal vein (rf), which is generally but incorrectly described as the 
 inferior longitudinal sinus, may be regarded as an ordinary vein enclosed within the pos- 
 terior half of the free margin of the falx cerebri. This vein increases in size from be- 
 fore backward, and enters directly into the straight sinus. It sometimes bifurcates be- 
 fore its termination, and then the lower branch of the bifurcation opens into the anterior 
 extremity of the straight sinus, and the upper describes a decided curve, and enters at 
 the middle of that sinus. 
 
 The inferior longitudinal vein receives the proper veins of the falx cerebri. It seldom 
 receives any vein belonging to the brain itself. 
 
 The ventricular veins, or vena Galeni (c), are two in number, one proceeding from the 
 left, and one from the right lateral ventricle. Each of them is formed by the union of two 
 branches, viz., the choroid vein, and the vein of the corpus striatum. 
 
 The choroid vein runs along the whole length of the outer border of the choroid plexus, 
 m a direction from behind forward. During this course it receives the vein from the 
 hippocampus major, one from the fornix, and one from the corpus callosum, and having 
 reached the anterior extremity of the choroid plexus, it turns back again within the sub- 
 stance of the plexus, and unites with the vein of the corpus striatum. 
 
 The vein of the corpus striatum is much smaller than the preceding ; it commences be- 
 hind in the furrow between the corpus striatum and the thalamus opticus, traverses the 
 whole length of that furrow, covered by the taenia semicircularis, receives, during its 
 course, a great nmnber of small veins from the corpus striatum and thalamus opticus, 
 and having arrived behind the anterior pillow of the fornix, unites with the choroid vein 
 to form one of the venae Galeni. 
 
 The two vena Galeni proceed parallel with each other, and horizontally backward be- 
 neath the velum interpositum, pass out from the brain beneath the corpus callosum, and 
 immediately enter the straight sinus below the opening of the inferior longitudinal vein 
 without crossing each other, as is stated by some anatomists. 
 
 Not unfrequently we find an anterior and superior cerebellar vein opening into the ve- 
 nae Galeni, as the latter enter the straight sinus. 
 
 The inferior median cerebral veins are very large. One is anterior, and commences 
 upon the fore part of the lower surface of the cerebrum, and turns round its correspond- 
 ing crus ; while the other, which is posterior, arises upon the posterior convolutions ; 
 they both enter the anterior extremity of the straight sinus, behind the venas Galeni. 
 
 The superior mediaii cerebellar vein passes upward between the valve of Vieussens and 
 the superior vermiform process, and opens into the anterior extremity of the straight 
 sinus. 
 
 The Superior Petrosal Sinuses. 
 
 The superior petrosal sinuses {fffg- 221) are situated along the upper border of the 
 Pig, 221. petrous portion of the temporal bones, and are partly lodged 
 
 in the small corresponding grooves ; they are continuous as 
 regards their direction with the horizontal portion of each 
 lateral sinus, and occupy the anterior half of the lateral or 
 adherent borders of the tentorium, the lateral sinuses occu- 
 pying the posterior half They are very small, and, hke the 
 part of the lateral sinus with which they are continuous, 
 they are three-sided. The anterior extremity of each su- 
 perior petrosal sinus communicates with the corresponding 
 cavernous sinus {h h) ; and its posterior extremity opens 
 into the corresponding lateral sinus at the point where the 
 latter leaves the tentorium cerebeUi to turn round the base 
 of the petrous portion of the temporal bone. 
 
 The superior petrosal sinuses, therefore, establish a di- 
 rect communication between the cavernous and the lateral 
 sinuses ; they sometimes receive an inferior lateral cerebral 
 vein, but always an anterior lateral cerebellar vein, which 
 passes upward under the free margin of the tentorium cerebeUi, behind the fifth pair of 
 nerves. The veins which come from the sides of the pons Varolii also enter the an- 
 terior extremity of this sinus. 
 
 The Inferior Petrosal Sinuses. 
 
 The inferior petrosal sinuses (g g) are situated, one on each side, upon the petro-occip- 
 ital sutures, and lie in corresponding grooves ; each of them extends from the anterior 
 to the posterior lacerated foramen of- its own side. They are larger than the superior 
 petrosal sinuses, and are semi-cylindrical, like the anterior part of the lateral sinuses, 
 with which they are continuous. The anterior extremity of each opens into the anterior 
 
THE CAVERNOUS SINUSES, ETC. 
 
 occipital sinus (r) and into the cavernous sinus of its own side ; while its posterior ex- 
 tremity opens into the anterior end of the corresponding lateral sinus, opposite the com- 
 mencement of the internal jugular vein (s). These sinuses establish a free anastomosis 
 between the anterior and posterior sinuses found at the base of the cranium. 
 
 Excepting one vein which comes from the base of the cranium through the foramen 
 lacerum anticus, the inferior petrosal sinus receives no vein of importance. 
 
 The Cavernous Sinuses. 
 
 The cavernous sinuses (h h), so named from their reticulated, and, as it were, spongy 
 structure, occupy the sides of the sella turcica and the grooves on the body of the sphe- 
 noid bone. Each cavernous sinus is bounded in front by the inner part of the sphenoidal 
 fissure, and behind by the apex of the petrous portion of the temporal bone : its cavity 
 (shown on the right side in the figure) is larger than it at first sight appears to be, but is 
 encroached upon by the internal carotid artery, which curves twice upon itself during its 
 passage through the sinus, and also by the abducens oculi, or sixth cranial nerve. The 
 motor oculi or third nerve, the trochlearis or fourth, and the ophthalmic branch of the 
 fifth cranial nerve, are situated in the substance of tlie outer wall of the sinus. It is 
 traversed by reddish reticulated filaments, the nature of which is unknown. The older 
 anatomists said that the internal carotid artery and the sixth nerve were bathed in the 
 blood of the sinus ; but it is now generally believed, in accordance with the opinion of 
 Bichat, that they are protected by the lining membrane of the veins ; it is difficult to 
 prove the accuracy of this opinion, although analogy is in its favour. Bichat also thought 
 that the reticulated filaments mentioned above were folds of the lining membrane of the 
 vein. The anterior extremity of each cavernous sinus has been named the ophthalmic 
 sinus, doubtless on account of its being prolonged outward. Its posterior extremity opens 
 into the corresponding superior and inferior petrosal sinuses, and into the transverse oc- 
 cipital sinus. On the inner side it receives t)ie coronary sinus, which establishes a di- 
 rect communication between the right and left cavernous sinuses. Lastly, each cavern- 
 ous sinus receives below several branches, which connect the veins within with those 
 outside the base of the cranium, more particularly with the pterygoid venous plexuses. 
 
 The cavernous sinuses receive in front the inferior and anterior cerebral veins, which 
 commence upon the lower surface of the anterior lobe of the cerebrum. The largest of 
 these veins on each side reaches the sphenoidal fissure, turns backward over the lateral 
 and middle fossa of the base of the cranium, and enters the middle meningeal vein. 
 Several anatomists state that they have seen the middle meningeal veins open into the 
 cavernous sinuses. 
 
 Lastly, the anterior extremity of each of these sinuses receives the ophthalmic vein. 
 
 The ophthalmic vein is a very large vessel, which commences on the inner side of the 
 orbit as a continuation of the frontal vein, and terminates by opening into the anterior 
 extremity of the corresponding cavernous sinus ; and it thus establishes a very free com- 
 munication between the veins of the interior and exterior of the cranium. It pursues 
 the same course as the ophthalmic artery, but without any windings, and receives venous 
 branches corresponding to the ramifications of that artery. Among them, I shall men- 
 tion particularly the ciliary veins, which commence in the choroid membrane of the eye, 
 where they are called vasa vorticosa, on account of being arranged in whirls. 
 
 The Coronary Sinus. 
 
 The coronary sinus, or circular sinus of Ridley (i), runs round the margin of the pituitary 
 fossa, and completely surrounds the pituitary body. Its posterior is much larger than 
 its anterior half. In old subjects it is not rare to find the quadrilateral plate of the sphe- 
 noid bone behind the pituitary fossa worn away, as if corroded by the blood of the sinus, 
 so that it may easily be broken. At this period of life, the coronary sinus is larger than 
 in young subjects, and extends under the pituitary body itself 
 
 The coronary sinus only receives osseous veins from the sphenoid, some veins from 
 the dura mater, and those from the pituitary body. It opens freely on each side into the 
 cavernous sinuses, which thus communicate with each other. 
 
 The Anterior Occipital, or the Basilar Sinus. 
 
 The anterior or transverse occipital sinus (r) is median and single ; it extends trans- 
 versely across the basilar groove from the foramen lacerum posticus of one side to that 
 of the other ; it is of an irregular form, much larger in the aged than in adult and young 
 snbjects, and connects the superior and inferior petrosal sinuses and the ca\ ernous sinus 
 of one side with the corresponding sinuses of the opposite side. In old subjects, the 
 basUar surface not unfrequently appears as if corroded opposite this sinus, the cavity ol" 
 which often presents a cellular or spongy structure. 
 
 The Posterior Occipital Sinuses. 
 These {k k) are the smallest of all the sinuses of the dura mater ; they commence one 
 at each foramen lacerum posticus, pass from thence upon each side of the foramen 
 
688 ANGEIOLOGY. 
 
 magnum, converge towards the falx cerebelli, enter its substance, and open separately 
 into the confluence of the sinuses : they receive some small veins from the bones of the 
 cranium and from the dura mater : the posterior occipital sinuses may be said to repre- 
 sent the chord of the arc formed by the lateral sinuses.* 
 
 The Confluences of the Sinuses. 
 
 From what has been stated above, it appears that there are three central points in 
 which all the sinuses meet : one situated behind and in the middle line, and one on each 
 side of the middle line in front. The term confluence of the sinuses might be applied to 
 all three points, but it has hitherto been confined to the posterior and median central 
 point, or occipital confluence. All the sinuses open directly into one of these three 
 points, the inferior longitudinal, if it be considered a sinus, forming the only exception. 
 
 The Posterior or Occipital Confluence, or Torcular Herophili. — If that portion of the dura 
 mater which corresponds to the occipital protuberance be opened from behind, six ori- 
 fices will be exposed to view, viz., a superior, which belongs to the superior longitudinal 
 sinus ; an anterior, sometimes divided into two by a vertical band, which belongs to the 
 straight sinus ; two lateral orifices, which belong to the two lateral sinuses ; and two in- 
 ferior, which belong to the posterior occipital sinuses. The point at which these sinuses 
 meet is named the torcular Herophili (n n,figs. 220, 221), because it is supposed that the 
 columns of blood flowing from the different sinuses must, in some degree, press against 
 each other. 
 
 The Anterior or Petro- sphenoidal Confluence. — Between the apex of the petrous portion 
 of the temporal bone and the sphenoid bone, there is on each side another confluence, 
 at which a great number of sinuses meet, viz., in front, the cavernous sinus and the cor- 
 onary sinus ; on the inside, the transverse occipital sinus ; and behind, the superior and 
 inferior petrosal sinuses. 
 
 The Branches op Origin of the Jugular Veins. 
 
 The Facial Vein. 
 
 The facial, or external maxillary vein (e, fig. 219), represents the artery of the same 
 name ; also the terminal divisions of the ophthalmic artery ; and, lastly, some of the 
 branches of the internal maxillary artery. 
 
 It commences in the frontal region, where it is called the frontal vein ; at the inner 
 angle of the eye it is named the angular vein ; and afterward the facial vein until its ter- 
 mination. 
 
 The frontal vein (la vein preparate, a, fig. 219) is a sub-cutaneous vein, which was se- 
 lected by the ancients for phlebotomy : it is sometimes single, and is then placed in the 
 median line ; but there are generally two frontal veins united by a transverse anasto- 
 mosis. Among the numerous varieties which this vein presents, I shall point out one 
 in which the two frontal veins are united into a single trunk, which bifurcates above the 
 root of the nose. These veins do not exactly follow the course of the frontal arteries ; 
 they descend from the vertex, where, by their numerous anastomoses, either with each 
 other or with the temporal veins, they form a venous plexus large enough to cover the 
 whole frontal region. They open into a transverse venous arch, having its concavity 
 directed downward ; it is sometimes tortuous : it is situated at the root of the nose, and 
 is named the nasal arch (t). This arch is also joined by the supra-orbital vein, a deep- 
 seated vessel (indicated by the dotted lines c), which runs transversely along the upper 
 part of the orbit, receives the superior internal palpebral vein, and opens into the ex- 
 tremity of the arch, on the outer side of the frontal vein : the ophthalmic vein also termi- 
 nates in the nasal arch of the vein, between which and the cavernous sinus it establishes 
 a free communication. Thus the upper parts of the face, more particularly the eye and 
 its appendages, are intimately connected with the brain through the medium of the veins 
 as well as of the arteries. Moreover, the dorsal veins of the nose, which run on each side 
 of the ridge of that organ, open into the concavity of the nasal arch. 
 
 The angular veins are given off from the right and left extremities of the nasal arch, 
 and may be regarded as the continuations of the frontal veins ; like the corresponding 
 arteries, each of them (d) is situated in the furrow between the nose and the cheek. 
 The inferior palpebral vein and the vein of the lachrymal sac and nasal duct enter the outer 
 side of each angular vein, which is joined on its inner side by the veins of the corre- 
 sponding ala of the nose. 
 
 The veins qf the ala nasi form a very dense network between the cartilage and the skin, 
 and also between the cartilage and the mucous membrane ; from these networks two 
 branches are given off: a superior, which runs along the convex border ; and an infe- 
 rior, which runs along the lower border of the inferior lateral cartilage, or the cartilage 
 of the ala. These two branches unite into a very large common trunk, which passes 
 upward, often very obliquely, into the angular vein. 
 
 The facial vein (e) commences in the angular vein, at the point where the latter is 
 
 * [They sometimes join the lateral sinuses in front, as shown in the figure.] 
 
THE TEMPORO-MAXILLARY VEIN. 58^ 
 
 joiaed by the veins of the nose ; it proceeds very obhquely dovi^nward and outward, 
 passes under the great zygomatic muscle, reaches and then runs along the anterior bor- 
 der of the masseter, crosses at right angles over the base of the jaw, is received into a 
 groove in the sub-maxillary gland, and terminates in several different modes. 
 
 Most commonly, it unites with the lingual to form a common trunk, which enters the 
 internal jugular ; it is into this common trunk of the facial and lingual veins that the su- 
 perior thyroid and the pharyngeal vein, and the common trunk of the temporal and inter- 
 nal maxillary veins, sometimes open. In other cases the facial vein passes obliquely 
 across the outer surface of the sterno-mastoideus, and enters at some point of the exter- 
 nal jugular vein. I have seen it directly continuous with the anterior jugular, also with 
 the external jugular of the same or of the opposite side, or it may enter the convexity 
 of an arch of conununication between the external and anterior jugular veins. 
 
 Collateral Branches. — During its course the facial vein in joined on its outer side by the 
 alveolar venous trunk, which is very large, and may be regarded as the deep branch of 
 origin of the facial vein, which, in fact, becomes much larger, sometimes even twice as 
 large, after its reception. This alveolar trunk commences in a very remarkable venous 
 plexus, named the alveolar plexus, in which the alveolar veins ■properly so called, together 
 with the infra-orbital, superior palatine, vidian, and spheno-palatine veins terminate, and 
 which communicates with the pterygoid plexus. All these veins accompany the branches 
 of the internal maxillary artery having the same names. From the alveolar plexus the 
 alveolar trunk runs forward and downward below the malar bone, and unites obliquely 
 with the facial vein. The facial is also joined on its inner side by the superior and infe- 
 rior coronary veins of the lip, which are distributed like the arteries, but are not tortu- 
 ous ; by the buccal vein or veins ; and by the anterior masseteric veins. 
 
 Below the base of the jaw, the facial vein is joined by the sub-mental vein ; by the in- 
 ferior palatine, which is remarkable for the plexus around the tonsils, which is formed al 
 most entirely by it ; also by the vein or veins from the sub-maxillary gland, and some- 
 times by the ranine vein. 
 
 During its course the facial vein is, in general, more superficial than the facial artery, 
 and does not accompany it on the face, but is situated more to the outside, and is not 
 tortuous. 
 
 The Temporo-maxillary Vein. 
 
 The temporo-maxillary vein, or venous trunk, represents the temporal artery, a part of 
 the internal maxillary, and the upper part of the external carotid : many authors follow 
 Walther in naming it the posterior facial vein, in contradistinction to the facial vein prop- 
 erly so called, which they name the anterior facial. The temporo-maxillary is formed 
 by the junction of the temporal and internal maxillary veins : it most frequently termi- 
 nates in the external jugular vein. 
 
 The Temporal Vein. — This vein commences above by superficial, middle, and deep 
 branches. 
 
 The superficial temporal veins (f,fig. 219) commence upon the crown of the head by 
 anterior or frontal branches, which communicate freely with the origin of the frontal vein, 
 by middle or parietal branches, which communicate with the corresponding branches of 
 the opposite side, and by posterior or occipital branches, which communicate with the 
 branches of the occipital vein. These form a very open network over the greater part 
 of the cranium. From this network anterior and posterior branches arise, and unite 
 with each other above or opposite to the zygomatic arch. During this course the veins 
 do not exactly follow the direction of the corresponding arteries. It might be said that 
 the veins of the scalp partake of the characters both of the venae comites and the sub- 
 cutaneous veins. These venous networks are, moreover, situated in the substance of 
 the hairy scalp, and, like the arteries, are placed between the skin and the occipito- 
 frontalis muscle. 
 
 The middle temporal vein is a very large vessel, often much larger than the common 
 trunk of the superficial veins. It is situated (as indicated by the dotted lines, g,fig. 219) 
 beneath the temporal fascia, between it and the temporal muscle. It is sometimes 
 formed principally by the junction of the palpebral with the external orbital veins, which, 
 corresponding in their distribution to the arteries of the same name, unite into a common 
 trunk that runs backward at first between the two layers of the temporal fascia, then be- 
 tween the muscle and the fascia, is directed backward and downward, again perforates 
 the fascia from within outward above the antero-posterior root of the zygomatic process, 
 and unites with the superficial temporal vein in front of the external auditory meatus. 
 
 The trunk resulting from the junction of the superficial temporal and middle temporal 
 veins passes vertically downward, between the external auditory meatus and the tem- 
 poro-maxillary articulation, dips into the substance of the parotid gland, and, having ar- 
 rived behind the neck of the condyle, receives the internal maxillary vein, wliich consti- 
 tutes the deep origin of the temporo-maxillary trunk. 
 
 The Internal Maxillary Vein. — This vein, the deep origin of the temporo-maxillary trunk, 
 is called by Meckel the internal and posterior maxillary, in opposition to the alveolar branch 
 
600 «*> ANGEIOLOGY. 
 
 of the facial vem/wRicIi^lie calls the internal and anterior maxillary: it corresponds to all 
 the branches given off from the internal maxillary artery behind the neck of the condyle, 
 in the zygomato-maxillary fossa ; while the alveolar vein, the deep branch of the facial, 
 corresponds to all the branches given off by the internal maxillary artery upon the tuber- 
 osity of the superior maxilla and in the pterygo-maxillary fossa. 
 
 Thus it is joined by the middle meningeal veins. The venae comites of the middle me- 
 ningeal artery, the existence of which has been erroneously denied, are two in number, 
 and are situated, one in front, the other behind the artery. These veins often receive 
 some inferior and anterior cerebral veins, which enter them near the foramen spinosum 
 of the sphenoid ; they always receive veins from the bones of the cranium and from the 
 dura mater, and communicate with the superior longitudinal sinus ; they are sometimes 
 so large, especially the anterior branch, that they have deep grooves formed for them 
 upon the sphenoidal fossa, reaching from the foramen spinosum to the point of the great 
 ala of the sphenoid bone. Lastly, the distribution of the middle meningeal veins is sim- 
 ilar to that of the corresponding artery. 
 
 The internal meixillary vein is also joined by the inferior dental, by the deep temporal, 
 by the pterygoid, and by the posterior masseteric veins. All of these veins communicate 
 with a very large and important venous plexus, the pterygoid plexus, situated between 
 the temporal and external pterygoid muscles, and between the two pterygoid muscles. 
 In this plexus, which communicates freely with the alveolar plexus, so freely, indeed, 
 that they may be regarded as forming but a single plexus, the internal maxillary vein 
 commences and joins the temporal vein, behind the neck of the condyle of the lower jaw. 
 
 The temporo-maxillary trunk, thus formed by the junction of the temporal with the 
 internal maxillary vein, is much larger than the former vein, and continues its course 
 through the substance of the parotid gland ; it is joined directly by some parotid veins, 
 by the posterior and anterior auricular veins, and, lastly, by the transverse veins of the face. 
 The last-named veins form, between the parotid gland and the masseter muscle (j, fig. 
 219), between that muscle and the ramus of the lower jaw, and around the temporo-max- 
 illary articulation, a very large plexus, named the masseteric plexus, which communicates 
 freely with the pterygoid plexus through the sigmoid notch. 
 
 Termination of the Temporo-maxillary Trunk. — Most commonly the temporo-maxillary 
 vein or trunk terminates directly in the external jugular vein (h) ; at other times it enters 
 the internal jugular, and then there is merely a trace of the external jugular, which is 
 formed principally by the superficial branches of the occipital vein, and by some commu- 
 nicating branches from the anterior jugular. In some cases, the temporo-maxillary vein 
 is almost equally divided between the internal and external jugulars ; lastly, it is some- 
 times united to the lingual and the facial vein : when it ends in the external jugular, it 
 sends to the internal jugular a large conmiunicating branch which passes above the di- 
 gastric muscle. 
 
 The Posterior Auricular Vein. 
 The posterior auricular vein follows the distribution of the artery of that name ; it re- 
 ceives the stylo-mastoid vein, and enters the external jugular, or, rather, the temporo- 
 maxillary vein, which does not take the name of external jugular until after it is joined 
 by this vein. 
 
 The Occipital Vein. 
 
 The occipital vein is distributed in the same manner as the occipital artery ; it com- 
 mences at the back of the cranium, passes beneath the splenius muscle, and is joined 
 opposite the mastoid process by one or more large mastoid veins, which come from the 
 corresponding lateral sinus, establishing a direct and free communication between the 
 venous circulation in the interior and exterior of the cranium. It was this that led Mor- 
 gagni to prefer the occipital veins for the purpose of bloodletting in apoplexy. The oc- 
 cipital vein ends in the internal, and sometimes in the external jugular. 
 
 The Lingual Veins. 
 
 The lingual veins, being intended for a contractile organ, the circulation in which is on 
 that account liable to be much interfered with, are divided, hke the veins of the limbs, 
 into the superficial or suh-mucous, and the deep veins. 
 
 The superficial veins of the dorsum of the tongue, which are generally named the lingual 
 veins, occupy the dorsal region of the tongue, ramifying in a remarkable manner between 
 the mucous membrane and the muscular fibres of that organ : all these veins open into 
 a dorsal or superior lingual plexus, which is situated at the base of the tongue, and is 
 joined by a great number of veins from the tonsils and epiglottis. 
 
 The satellite vein of the lingual nerve emanates from this plexus, accompanies the lin- 
 gual nerve, receives some branches from the sub-lingual glands and the tissue of the 
 tongue, and enters the facial or the pharyngeal vein, or terminates directly in the exter- 
 nal jugular, communicating freely with the ranine veins. 
 
 The ranine veins are the superficial veins of the lower surface of the tongue. They 
 
THE PHARYNGEAL VEIN, ETC. 991 
 
 are seen one upon each side of the fraenum, where they form a ridge beneath the mucous 
 membrane. Each of them accompanies the corresponding hypoglossal nerve, between 
 the genio-hyoglossus and hyoglossus muscles, and terminates either in the common 
 trunk of the lingual and facial veins, or directly in the facial vein. 
 
 The ranine veins communicate upon the sides of the tongue with a very large plexus, 
 the vessels composing which are sometimes provided with valves, so that it is impossi- 
 ble to inject it in a direction from the heart towards the extremities of the veins, which, 
 in other cases, may be done with the greatest facility. 
 
 Lastly, the lingual veins, properly so called, are extremely small; they are two in 
 number, and accompany the lingual artery throughout the whole of its course. Not un- 
 frequently the veins of the tongue terminate directly in the internal jugular : I have seen 
 them open into the anterior jugular. 
 
 The Pharyngeal Vein and Pharyngeal Plexus. 
 
 The Pharyngeal Plexus. — In making the section already described for examining the 
 pharynx, we observe round the back of that organ a considerable venous plexus, which 
 forms loops or rings for embracing the pharynx ; several meningeal branches, and some 
 derived from the vidian and spheno-palatine veins, open into this plexus ; from which a 
 variable number of pharyngeal branches arise, and terminate by a common trunk, or by 
 several distinct branches, in the lingual vein, sometimes in the facial or the inferior thy- 
 roid, and frequently in the internal jugular. 
 
 Besides this plexus, which may be called the superficial pharjTigeal plexus, an ex- 
 tremely dense network is found beneath the mucous membrane, from which branches 
 proceed to join with those that arise from the superficial plexus just described 
 
 The Superior and the Middle Thyroid Veins. 
 
 The superior thyroid, or thyro-laryngeal vein, commences upon the thyroid gland by 
 branches corresponding to the thyroid arteries, and upon the larynx by branches corre- 
 sponding to the ramifications of the superior laryngeal artery. The thyroid and laryn- 
 geal branches unite and end in the internal jugular vein, opposite the upper part of the 
 larynx ; they perhaps end more frequently in the common trunk of the facial and lingual 
 veins. It is not uncommon to find the superior laryngeal branch terminating directly 
 either in one or the other of these veins, or in the anterior jugular. 
 
 The middle thyroid vein arises from the lower part of the lateral lobe of the thyroid 
 gland, and is joined by some branches from the larynx and the trachea. By their union 
 they form a trunk, which ends in the lower part of the internal jugular vein. The con- 
 stant existence of this vein explains in some degree a rather frequent variety in the ar- 
 teries of the thyroid gland, viz., the existence of a middle thyroid artery given off by the 
 common carotid. Not unfrequently there are two middle thyroid veins on each side 
 These, as well as all the other thyroid veins, are much enlarged in goitre 
 
 The Veins of the Diplo'e. 
 
 To complete the description of the vessels of the head, it only remains for me to no- 
 tice the diploic veins, or the proper veins of the bones of the cranium. They were first 
 described by M. Dupuytren, in his inaugural thesis, under the name of venous canals of 
 the bones : they were afterward figured by M. Chaussier (Traite de V Encephale), and, to- 
 gether with their principal varieties, they have lately been represented with uncommon 
 accuracy by M. Breschet, in his admirable work upon the veins. 
 
 In the substance of the cranial bones there are found ramified venous canals, which 
 are occupied by veins, having only their internal membrane, the bony canals themselves 
 serving for an external coat. These venous canals are not exclusively confined to the 
 bones of the cranium : they exist in all spongy bones, and even in compact bones ; but, 
 while the canals are found in the entire substance of spongy bones, in the compact part 
 of the long bones they are situated near the medullary canal. 
 
 The venous canals of the bones of the cranium vary much in their size, and in the 
 extent to which they are distributed : they are independent of each other as long as the 
 cranial bones remain distinct and separable ; but they almost always communicate when, 
 in the progress of age, those bones become united together. They get larger and larger 
 as life advances, and their size is indirectly proportioned to the number of their ramifi- 
 cations : they sometimes present ampullae or dilatations, and at other times are suddenly 
 interrupted, and terminate in culs-de-sac, reappearing again farther on, or ceasing alto- 
 gether : these peculiarities depend upon the venous canal opening at different points 
 into the middle meningeal veins. Moreover, these venous canals communicate by a 
 number of orifices of different sizes, either in the interior of the cranium with the me- 
 ningeal veins, and with the sinuses of the dura mater, or on the exterior with the veins 
 which lie in contact with the bones of the scull. 
 
 In some heads of old subjects, these canals are found blended with the furrows for 
 the branches of the meningeal arteries ; those furrows- themselves present some large 
 foramina, which open into the cranium in various nlaces. 
 
69^ ANGEIOLOGY. 
 
 In new-born infants there are no venous canals, properly so called ; but the whole 
 substance of the bones is traversed by a venous network, which may be seen when its 
 constituent veins are naturally injected with blood, or when they have been filled with 
 mercury, by which as delicate a network of vessels can be shown in the diploe as in in- 
 jections of the soft parts. At this period all the cells of the bones are filled with venous 
 blood. 
 
 On the roof of the cranium the canals of the diploe are divided into the frontal, tempo- 
 ral, parietal, and occipital. 
 
 The frontal diploic canals are two in number, one on the right, the other on the left 
 side : they commence by numerous ramifications upon the upper part of the frontal 
 bones, increase in size as they approach the lower part of the roof of the scull, commu- 
 nicate with each other by transverse branches, and also with the periosteal or the me- 
 ningeal veins, open externally by vascular foramina, and then enter the supra-orbital 
 and frontal veins. 
 
 The temporo-parietal diploic canals are divided into anterior and posterior : they corre- 
 spond to the furrows which contain the ramifications of the meningeal artery, and open 
 into those furrows by a great number of foramina, which become very distinct in advanced 
 life : they also communicate with the deep temporal veins on the exterior of the scull. 
 
 The occipital diploic canals, two in number, a right and a left, communicnte with each 
 other by a great number of branches, and open below into the occipital veins. 
 
 Summary of the Distribution of the Veins of the Head. 
 
 Circulation in the Brain. — Corresponding to two of the arterial trunks, the common 
 carotids, which convey blood to the head and neck, there are six veins, to return it back 
 to the heart from the same parts, viz., the two internal, the two external, and the two 
 anterior jugulars. This arrangement tends to prevent interruption of the venous circu- 
 lation in the head, which, from so many causes, is liable to be disturbed. The external 
 and anterior jugular veins belong to the sub-cutaneous venous system, and may be re- 
 garded as supplementary veins which have no corresponding arteries, and which would 
 be sufficient of themselves to carry on the venous circulation ; and as the veins of the 
 right and left sides communicate very freely with each other, it follows that one of them 
 would suffice to return the blood from the head. It will be seen hereafter, when de- 
 scribing the veins of the spine, that the obliteration of all the six jugular veins would 
 not of necessity be followed by interruption of the venous circulation in the cranium. 
 Lastly, it is important to observe, that the external and anterior jugulars open into the 
 sub-clavian vein, while the internal jugular joins the inner end of the sub-clavian, to 
 form the brachio-cephalic vein. 
 
 We have seen that the lower part of the internal jugular vein represents the common 
 carotid, and the upper part of it the internal carotid ; and that the external carotid is 
 represented by all the veins of the face and neck, which open into the internal jugular 
 either by a common trunk, or by several distinct branches. 
 
 The cerebral venous system is remarkable for the extreme thinness of the parietes 
 of the veins upon the brain, and for the existence of the sinuses, which take the place 
 of the venous trunks, and differ so much in their distribution from the arteries. The 
 cerebral veins are divided into the ventricular veins, which go to form the venae Galeni, 
 and the superficial veins of the brain. All of them run towards the sinuses, in which they 
 terminate in succession like the barbs of a feather upon the common shaft, but do not 
 acquire a great size. From the absence of valves at their orifices into the sinuses, the 
 blood may regurgitate into them. The presence of the spongy areolar tissue at the or- 
 ifices of these veins, together with their oblique course through the walls of the sinus, 
 must diminish this regurgitation : the communication of the cerebral veins with each 
 other, and the continuity of the several sinuses, explain the varied means contrived for 
 carrying on the cerebral circulation, which can only be interrupted by obliteration of the 
 lateral sinuses. 
 
 Lastly, the position of the principal sinuses opposite the fissures between the great di- 
 visions of the encephalon, and the resisting nature of the walls of the sinuses themselves, 
 prevent the fatal effects which might otherwise ensue from compression produced by 
 obstruction of the venous circulation. 
 
 Circulation in the Parietes of the Cranium. — In the parietes of the cranium we find the 
 veins of the dura mater, the veins of the diploe, the periosteal veins, and the veins of 
 the hairy scalp. The numerous communications existing between these four systems 
 of veins, and the direct communications established between the sinuses of the dura 
 mater and the veins on the exterior of the scull, are worthy of particular attention. I 
 would observe that the principal veins of the scalp, like the arteries of the same part, 
 are situated between the skin and the epicranial aponeurosis. I have ascertained the 
 existence of free and frequent anastomoses among these veins. As at the back of the 
 cranium there is a very free communication between the occipital vein and the lateral 
 sinus by means of a large vein, so, also, along the superior longitudinal groove, and op 
 posite the sutures upon the base of the scull (through most of the foramina found in that 
 
THE DEEP VEINS OP THE UPPER EXTKEMITY. 593 
 
 ntoation), an uninterrupted communication is established between the veins within and 
 ^ose outside the cranium. 
 
 Venous Circulation of the Face. — ^All the veins of the face and of the parietes of the 
 cranium end in two principal trunks, the facial and the temporal. The facial vein cor« 
 responds to a part of the internal maxillary artery, to a part of the ophthalmic artery, 
 and to the facial artery properly so called. One of the most remarkable circumstances 
 connected with the distribution of the facial vein is the communication between it and 
 the cavernous sinus, established at the inner angle of the orbit by means of the ophthal- 
 mic vein, so that the veins on the inside and on the outside of the cranium are most in 
 timately connected.* 
 
 The temporal vein represents the temporal artery, a part of the internal maxillary ar- 
 tery, and the upper part of the external carotid, and returns the blood from the entire 
 side of the head. 
 
 With regard to the veins of the tongue, we should remark the existence of two sub- 
 mucous veins, corresponding to the sub-cutaneous veins in the limbs, and intended to 
 return the blood, instead of the deep veins of the tongue, during the contractions of that 
 organ. 
 
 The size of the superior middle thyroid veins, their number, which exceeds that of 
 the arteries, and their free anastomoses with the inferior thyroid veins, render them an 
 important medium of circulation when the passage of the blood from the head is obstruct 
 ed, and, at the same time, a diverticulum in great impediments to the circulation. 
 
 The irregularity which exists in the relative size of the internal, external, and ante- 
 rior jugular veins, and also in the distribution of the veins of the head between these 
 three trunks, proves that, in the venous as well as in the arterial system, the origin or 
 termination of the vessels is of little importance, and that, after the venous system of 
 any part is once formed, it matters but little with which of the great vascular trunks it 
 is connected. 
 
 Lastly, the free communications which exist between all the preceding veins afford 
 sufficient evidence that but little interest need be attached to their termination in one 
 or another of the principal venous trunks. 
 
 The Deep Veins of the Upper Extremity. 
 The veiTts of the upper extremity are divided into the deep and the superficial or sub- 
 cutaneous. 
 
 The Palmar^ Radial, Ulnar, Brachial, and Axillary Veins. 
 
 The deep veins of the upper extremity exactly follow the course of the arteries, form 
 their venae comites, and take the same names : there are almost always two to each ar- 
 tery. The large venous trunks alone form exceptions to this rule. Thus, there are two 
 superficial and two deep palmar veins ; two deep radial and two deep ulriar veins ; we also 
 find two brachial veins ; but there is only one axillary and one suh-clavian vein. All these 
 venae comites receive branches formed by the union of still smaller ones, which are them- 
 selves the vense comites of the ramifications of the arteries, there being two veins with 
 each small artery. The sub-clavian vein, however, is an exception to this, for it does 
 not receive all the veins which correspond to the branches of the sub-clavian artery ; 
 while, on the other hand, it receives other veins that are totally unconnected with the 
 distribution of that artery. I ought to allude, in this place, to a mode of termination of 
 the collateral veins, which is frequently observed, especially in the brachial vein. The 
 circumflex veins, for example, instead of entering the brachial vein directly, terminate 
 in a collateral branch, which runs parallel to the brachial vein, like a canal running along- 
 side a river, and communicates with that vein above and below. Several large veins 
 have these collateral caneils, which establish a communication between different points 
 of their length. Thus, I have seen a venous trunk proceed from the external jugular, de- 
 scend through the brachial plexus of nerves, and enter the lower part of the axillary vein. 
 
 The deep veins, moreover, communicate freely and frequently with the superficial 
 veins. They are also provided with valves, like the superficial veins, and, it appears, 
 even with a greater number : an injection thrown from the heart towards the extrem- 
 ities will not enter more readily into one than into the other set. We always find two 
 valves at the mouth of a small vein where it opens into the larger trunk ; and it is a re- 
 markable fact that, while the valves situated in the course of the veins are sometimes 
 passed by the injection, those which are placed at the mouths of the small veins are 
 scarcely ever overcome. 
 
 The Sub-clavian Vein. 
 The term suh-clavian is generally given to all that portion of the brachial venous trunk 
 
 * The study of these anastomoses ought to lead us again to have recourse to those local venesections which 
 have fallen into disuse since the discovery of the circulation ; and it will enable us to determine, on anatomi- 
 cal grounds, the proper places at which they should be performed. Thus, it appears to me that we might ad- 
 vantageously introduce into jiractice bleeding from the angular vein in diseases of the eye ; from over the mas- 
 toid region, and the point wl'.ch corresponds to the junction of the longitudinal with the lambdoidal suture, in 
 cerebral affections; and bleeding from the ranine vein in diseases of the pharynx. 
 
 4 F 
 
694 ANGEIOLOGY. 
 
 which extends from the vena cava superior to the scaleni muscles ; but this vein may 
 be described more naturally, as being limited internally by the brachio-cephalic vein, or, 
 rather, by the junction of the internal jugular vein with the venous trunk of the upper 
 extremity, and externally by the clavicle, or, rather, by the costo-coracoid, or sub-cla- 
 vian aponeurosis. If the sub-clavian veins be thus defined, they will be of equal length 
 on both sides ; and the left vein, and even the right vein also, will be shorter than the 
 corresponding artery. 
 
 The direction of the sub-clavian veins differs much from that of the arteries : we have 
 Seen that the sub-clavian arteries describe a curve over the apex of the lung, with its 
 concavity turned downward ; the sub-clavian veins, on the contrary, proceed directly 
 outward as far as the first rib, over which they bend, so that they resemble the cord of 
 the arc described by the sub-clavian artery. We have seen, also, that the inferior thy- 
 roid vein, the internal mammary, the vertebral, the supra-scapular, the posterior scapu- 
 lar, the deep cervical, and the left superior intercostal veins, enter not into the sub-cla- 
 vian, but either into the superior vena cava, or into the brachio-cephalic vein. The right 
 superior intercostal vein, when it exists, that is to say, when the branches which should 
 form it do not terminate separately in the vena azygos, is the only one of the veins cor- 
 responding to the branches of the sub-clavian artery which opens into the sub-clavian vein 
 
 The external jugular, the anterior jugular, and a small branch from the cephalic vein 
 of the arm, also terminate in the sub-clavian vein. It would therefore, in some respects, 
 be proper to describe the external and anterior jugulars in connexion with the sub-cla- 
 vian vein, instead of with the internal jugular. I would remark, that the external and 
 anterior jugulars frequently terminate, not in the sub-clavian vein, but at the point where 
 it ends in the brachio-cephaUc vein, in front of the internal jugular. 
 
 Relations. — In front of the sub-clavian vein is situated the clavicle, which is separated 
 from the vein only by the sub-clavian muscle, so that this vessel may be wounded in 
 fractures of the clavicle : a very dense fibrous sheath binds it down to the sub-clavius 
 muscle ; and it perforates the costo-coracoid or sub-clavian aponeurosis, which adheres 
 to it, and keeps it open when cut across ; behind the vein is the sub-clavian artery, from 
 which it is separated, towards the inner part, by the scalenus anticus ; below, it is in re- 
 lation with the pleura and with the first rib, on which there is a corresponding but slight 
 depression ; above, it is covered by the cervical fascia, which separates it from the skin : 
 a considerable swelling is often seen in this region when the venous circulation is ob- 
 structed. 
 
 The Superficial or Sub-cutaneous Veins of the Upper Extremity. 
 The sub-cutaneous veins of the upper extremity belong essentially to the skin and to the 
 subjacent adipose tissue, since all the branches from the muscles enter the deep veins. 
 The superficial are larger than the deep veins, with which they communicate freely at a 
 great number of points ; and it may be remarked, that the size of the one set of vessels 
 is always inversely proportioned to that of the other set. We proceed to describe them 
 in succession in the hand, the forearm, and the arm. 
 
 The Superficial Veins of the Hand. 
 
 All the largest veins of the hand are situated upon its dorsal aspect ; and it is worthy 
 of notice, that the largest arteries, on the contrary, occupy the palm of the hand. If the 
 superficial veins had existed on the palmar aspect, the venous circulation would have 
 been impeded whenever the hand was used in prehension. Entering into the large sub- 
 cutaneous network of veins situated upon the back of the hand are several branches, 
 which constitute the superficial, external, and internal collateral veins of each fingei , they 
 occupy the outer and inner borders of the dorsal surface of the fingers, and comnmni- 
 cate frequently on the dorsal surface of each phalanx and around the phalangeal artic- 
 xilations, but not upon the articulations themselves. 
 
 Opposite the lower part of each interosseous space, these collateral veins unite at an 
 acute angle, just as the digital arteries bifurcate at the same point. All the superficial 
 digital veins ascend vertically between the metacarpo-phalangeal articulations, which 
 they seem to avoid, and then enter into the convexity of a very irregular venous arch, 
 ■which is formed by a series of loops, at each of the junctions of which one of the digital 
 veins is seen to terminate. 
 
 From the concavity of this irregular arch, which is turned upward, are given off a 
 /greater or less number of ascending branches, which are sometimes formed directly by 
 ■ the junction of the digital veins, without the intervention of an arch. Among these 
 branches, we should especially notice the external branch, which is situated nearest to 
 the first metacarpal bone, and is called the cephalic vein of the thumb; also the innermost 
 branch, which corresponds to the fifth metacarpal bone, and, for some reason not very 
 '.well known, has been named the vena salvatella. 
 
 The Superficial Veins of the Forearm. 
 "The superficial veins are much more numerous on the anterior than on the posterior 
 
THE SUPERFICIAL VEINS AT THE ELBOW, ETC. 595 
 
 aspect of the foreann. We find there the radial vein or veins, the ulnar vein, and the 
 median vein. 
 
 The superficial radial vein (r, in the representation of the superficial nerves of the arm) 
 is the continuation of the cephalic vein of the thumb ; it is situated along the outer side 
 of the carpus and of the radius, and it soon unites with some branches from the vena 
 salvatella, or vi^ith the salvatella itself The superficial radial vein often divides into 
 several branches, which are joined by others from the venous arch at the back of the 
 hand. There are sometimes two superficial radial veins. The vein or veins having 
 reached the middle of the forearm, turn forward upon the outer border of the radius, and 
 then continue to ascend vertically along the outer side of the anterior surface of the fore- 
 arm, up to the bend of the elbow. 
 
 The ulnar vein {u) commences partly from the vena salvatella, and another vein on the 
 dorsal region of the forearm, and partly from some branches which arise from the lower 
 part of the back of the forearm, and even from some small veins proceeding from the 
 thenar and hypothenar eminences. 
 
 The branches which arise from the vena salvatella and the back of the wrist pass for- 
 ward ; the other branches run backward ; the common trunk or trunks resulting from 
 their union are directed at first vertically upward, parallel with the superficial radial 
 vein, then somewhat obliquely forward, to anastomose with the median basilic vein, 
 above the bend of the elbow. When there is a second or posterior ulnar vein, it ends in 
 the basilic higher up, or else it anastomoses with the anterior ulnar vein. 
 
 Between the anterior radial and ulnar veins we find the common median or median vein 
 (m), formed by the anterior veins of the carpus and forearm. There may be more than 
 one median vein, and it is not unfrequently wanting, in which case its place is supplied 
 by a venous network, the branches from which enter separately into the radial and ulnar 
 veins. In some cases its place is supplied by an additional radial vein, and at other 
 times by the deep veins. 
 
 The Stiperficial Veins at the Elbow. 
 
 At the elbow all the veins are on the anterior aspect. The most common arrangement 
 is the following : on the outer side we find the upper portion of the radial vein or veins ; 
 on the inner sMe, the upper portion of the ulnar vein or veins, which pass in front of the 
 internal condyle of the humerus ; between the radial and ulnar veins is the median, 
 which divides into two branches : one external (a), which unites with the radial to form 
 the cephalic vein (c), and is called the median cephalic ; the other internal (e), generally 
 smaller, but more superficied than the preceding, which unites with the ulnar to form the 
 basilic vein {b), and is called the median basilic. 
 
 Several varieties are observed in the arrangement of the veins of the elbow ; some- 
 times the common median vein is wanting ; but then its cephalic and basilic branches 
 are given off by the radial, and the cephalic vein is almost always very small. In other 
 cases we only find two veins at the bend of the elbow, viz., the radial and the ulnar, 
 which are directly continuous with the cephalic and basilic. I once saw the common 
 median vein replaced by the anterior radial, and by a branch from one of the deep ulnar 
 veins. 
 
 The Superficial Veins in the Arm. 
 
 In the arm there are only two superficial veins, an external, named the cephalic vein, 
 and an internal or basilic. 
 
 The cephalic vein (c) is formed by the junction of the radial with the median cephalic 
 vein, which junction may occur at very different heights. It ascends vertically along 
 the outer border of the biceps ; then, running a Uttle inward, it gains the furrow be- 
 tween the deltoid and pectoralis major, passes over the summit of the coracoid process, 
 above or in front of which it curves backward, so as to enter the axillary vein immedi- 
 ately below the clavicle. From this curve the cephalic vein gives off a branch, which 
 passes in front of the clavicle, crosses at right angles over the middle of that bone, and 
 enters the sub-clavian vein. Not unfrequently the cephalic vein is replaced by a very 
 small branch. 
 
 The internal vein of the arm, which is called the basilic vein (i), is generally larger 
 than the cephalic. It is formed by the junction of the ulnar with the median basilic vein, 
 passes at first obliquely backward, and then vertically upward, in front of the internal 
 intermuscular septum, and enters either the brachial or the axillary vein. 
 
 General Remarks upon the Superficial Veins of the Upper Extremity. 
 From the preceding description, it follows that the cephalic vein forms the continua- 
 tion of the radial, which is itself the continuation of the cephalic vein of the thumb, and 
 that the basilic is a prolongation of the ulnar, which is a continuation of the vena salva- 
 tella. The median vein, placed as it is between the radial and ulnar veins, bifurcates 
 so as to tei-minate equally in the two latter veins, and estabhshes a free anastomosis be- 
 tween them. • , 
 
998 ANGEIOLOGY. 
 
 The anastomoses of the several sub-cutaneous veins together are very numeroois, and 
 enable them mutually to supply the place of each other. The anastomoses betvireen the 
 sub-cutaneous and deep veins are not less numerous. 
 
 Thus, the superficial collateral veins of the fingers communicate with the deep collat- 
 eral veins : communications exist between the superficial and deep veins of the carpus ; 
 very large communications exist between the two sets of vessels at the bend of the el- 
 bow, so that, in fact, they are continuous with each other ; thus, the superficial radial 
 vein is sometimes continuous with one of the deep radials, and the median, as it divides 
 into the median basilic and median cephalic, occasionally sends a very large branch to 
 the brachial. In one case, where the median vein was wanting, I found that the ulnar, 
 the deep interosseous, and the deep radial veins, formed a plexus, which gave oflT two 
 branches, an external to the cephalic, and an internal, which formed the deep brachial 
 vein. The superficial ulnar veins often communicate freely with the deep ulnar, beneath 
 the muscles attached to the internal condyle. 
 
 Along the arm, the basilic vein communicates with one of the brachial veins by several 
 transverse branches. Not unfrequently the basilic vein communicates with the brachial 
 by a very delicate branch, which forms a lateral canal. 
 
 Valves. — ^The valves are more numerous in the deep than in the superficial veins ; 
 they increase in number as we approach the upper part of the arm, and are much more 
 numerous in the basilic than in the cephalic vein. There are three in that part of the 
 cephalic which corresponds to the furrow between the deltoid and the pectoralis major. 
 There is one at the opening of the cephalic into the axillary ; another at the opening of 
 the basilic into the brachial ; all the small veins which enter the cephalic and basilic, as 
 well as those which terminate in the deep veins, are also provided at their openings 
 with valves, which prevent the regurgitation of the blood during life, and the passage of 
 an injection from the heart towards the extremities. 
 
 General Relations. — The sub-cutaneous veins are separated from the skin by the super- 
 ficial fascia, and by the layer of fat above it. The median basilic is the only exception, 
 for it is in contact with the skin, at least in the majority of subjects. 
 
 The sub-cutaneous veins must be carefully distinguished from the cutaneous veins, prop- 
 erly so called, which are in contact with the true skin, or even ramify in its substance, 
 and which are sometimes of considerable size, especially in the neighbourhood of certain 
 tumours. 
 
 From the relation of the median basilic vein with the brachial artery, over which it 
 crosses at a very acute angle, and from which it is separated only by the fibrous expan- 
 sion from the tendon of the biceps, it follows, that in emaciated persons the vein is al- 
 most in contact with the artery ; so that, in bleeding from the median basilic, if the vein 
 be perforated quite through, the artery may be wounded. The practical rules to be de- 
 rived from this anatomical fact are, in the first place, to avoid bleeding in the median 
 basilic as much as possible, and whenever it must be chosen, to open it either below 
 or above the point where it crosses over the artery. 
 
 In the description of the lymphatics and nerves of the arm, I shall point out their re- 
 lations with the superficial veins. I may now state, however, that the musculo-cutane- 
 ous nerve passes behind the median cephalic vein, and that the internal cutaneous di- 
 vides into several branches, some of which pass in front, and others behind the median 
 basilic vein. 
 
 THE INFERIOR OR ASCENDING VENA CAVA AND ITS BRANCHES. 
 
 The Inferior Vena Cava — the Lumbar or Vertebro-lumbar Veins — the Renal — the Middle 
 Supra-renal — the Spermatic and Ovarian — the Inferior Phrenic. — TVie Portal System of 
 Veins — the Branches of Origin of the Vena Porta — the Vena Porta — the Hepatic Veins. 
 — The Common Iliacs — the Internal Iliac — the Hemorrhoidal VeiTis and Plexuses — the 
 Pelvic Veins and Plexuses in the Male and in the Female. — The Deep Veins of the Lower 
 Extremity — the Plantar, Posterior, Tibial, Peroneal, Dorsal, Anterior Tibial, and Pop- 
 liteal — the Femoral — the External Iliac. — The Superficial Veins of the Lower Extremity 
 — the Internal Saphenous — the External Saphenous. 
 
 The vcTia cava inferior or ascendens, or the abdominal vena cava {I, fig. 222), is the large 
 venous trunk which returns the blood from all the parts below the diaphragm to the 
 heart. 
 
 It is formed below by the junction of the two common iliac veins (n n), opposite the 
 mtervertebral substance between the fourth and fifth lumbar vertebras ; it passes verti- 
 cally upward, and, having reached the lower surface of the liver, inclines a little towards 
 the right side, to gain the groove formed for it in the posterior border of that organ. At 
 the upper end of that groove the vena cava inferior perforates the tendinous opening in 
 the diaphragm, and also the fibrous layer of the pericardium, which is, as it were, blend 
 ed with the cordiform tendon at this point ; the vein then curves suddenly to the left, 
 and opens (r, fig. 192) horizontally into the posterior inferior part of the right auricle. 
 
THE VERTEBRO-liUMBAU VEINS, ETC. 597 
 
 It is larger than the vena cava superior, but is not of uniform caliber throughout ; for 
 example, it increases in size in a marked degree immediately above the renal veins. 
 The vena cava inferior presents also a second still larger dilatation opposite the liver, 
 vphere it is joined by the hepatic veins ; in comparison w^ith its diameter at that point, 
 the vena cava inferior appears to be slightly contracted as it passes through the dia- 
 phragm. 
 
 Relations. — The inferior cava is in contact with the anterior surface of the vertebral 
 column, and runs throughout the whole of its extent along the right side of the aorta ; it 
 inclines somewhat obliquely to the right as it is about to pass into the groove on the 
 liver. In front it is covered by the peritoneum, the third portion of the duodenum, the 
 pancreas, the vena portse, which crosses it at a very acute angle, and at its upper part 
 by the liver, which forms a semi-canal, or a complete canal for it. 
 
 It adheres closely to the margins of the tendinous opening in the diaphragm, and to 
 the fibrous layer of the pericardium, as if its outer coat were blended with those struc- 
 tures. 
 
 The serous layer of the pericardium covers the vein, but the fibrous layer does not 
 form a sheath for it. The relations of the inferior cava with the liver account for the 
 erroneous notion of some old anatomists, that this organ was the centre from which all 
 the veins of the body proceeded. 
 
 There is no valve in the inferior cava ; but at its termination we find the Eustachian 
 valve, which has been already described with the heart. 
 
 Branches of Origin. — We have stated that the junction of the common iliac veins con- 
 stitutes the origin of the inferior cava. It is very rare to find these veins uniting above 
 the intervertebral disc between the fourth and fifth lumbar vertebrae ; but in some few 
 cases the junction has been observed to take place opposite the renal veins. 
 
 Collateral Branches. — The vena cava inferior receives all the veins corresponding to 
 the branches of the abdominal aorta, excepting the veins from the alimentary canal and 
 its appendages, of which it only receives those from the liver, viz., the hepatic veins. 
 All the abdominal veins which do not open directly into the inferior cava unite to form 
 a large venous trunk, called the vena porta. Thus, the vena cava inferior receives the 
 renal, the spermatic or ovarian, the lumbar, the supra-renal, and the inferior phrenic 
 veins ; while the superior and inferior mesenteric, the splenic, the pancreatic, and the 
 gastric veins open into the vena portae. It may still be said, however, that the vena 
 cava inferior receives all the abdominal veins ; for, in fact, the veins of the portal sys- 
 tem terminate in the vena cava through the medium of the hepatic veins. The portal 
 system is, therefore, an appendage to the inferior cava. For this reason, and also for 
 the sake of economizing subjects, I shall not describe the vena portae and its branches 
 until I have noticed the collateral veins of the vena cava inferior. 
 
 The Lumbar or Vertebro-lumbar Veins. 
 
 The vertebro-lumbar veins are three or four on each side, and correspond to the arteries 
 of the same name ; they have two branches of origin : an external or abdominal branch, 
 which represents the intercostal veins, and a posterior or dorso-spinal branch, which is 
 itself formed by the union of two other branches ; one muscular or cutaneous, which com- 
 mences in the muscles and integuments, and the other a proper spinal branch, which 
 forms part of the rachidiau venous system, to be hereafter described. 
 
 By the junction of these two branches a lumbar vein is formed, which runs forward 
 and inward in the groove on the body of the corresponding lumbar vertebra, and enters 
 the vena cava at a right angle. The left lumbar veins are longer than the right, in con- 
 sequence of the vena cava being situated towards the right side of the vertebral column • 
 they pass under the aorta. 
 
 The Renal Veins. 
 
 The renal veins are remarkable for their size, and occasion a great increase in the 
 diameter of the inferior cava, above the point where they open into it ; they are of un- 
 equal size on the two sides, and are unequal in length, on account of the vena cava be- 
 ing placed towards the right side of the vertebral column, and, therefore, nearer the right 
 than the left kidney : they also run more obliquely on the right side, on account of the 
 right kidney being generally situated lower down than the left. 
 
 These veins commence in the substance of the kidney by a number of minute divisions, 
 which unite into small, and then into larger branches, gain the surface of the organ, and 
 are collected into a single trunk, either in the hilus or at some distance from it. The 
 trunk of each renal vein is always placed in front of the corresponding artery. The left 
 renal vein passes in front of the aorta. We sometimes find one division of the left renal 
 vein in front of the aorta, and another behind it. 
 
 Plurality of the renal vein appears to me less common than an excess in the number 
 of the arteries. 
 
 The renal veins receive the inferior supra-renal and several veins from the surrounding 
 
598 ANGEIOLOGY. 
 
 adipose tissue. The left renal vein is almost always joined by the spermatic or ovarian 
 vein of that side. 
 
 In some cases we find several communicating branches between the left renal vein 
 and the superior mesenteric, which is one of the branches of the portal system. 
 
 The Middle Supra-renal Veins. 
 The middle supra-renal or capsular veins, which are often numerous and very large, are 
 found on the surface of the supra-renal capsules, while the arteries enter into their sub- 
 stance from every point. The venous trunks run in the grooves seen upon the surface 
 of the organ. The left middle supra-renal vein almost always enters the renal vein of 
 the same side ; the right vein generally opens into the vena cava inferior. 
 
 The Spermatic or Ovarian Veins. 
 
 The spermatic veins commence in the interior of the testicle, where they form a great 
 number of those filaments which traverse the proper substance of the gland : they aU 
 terminate in branches, which are applied to the inner surface of the tunica albuginea, and 
 are bound down to it by a thin layer of fibrous tissue, a disposition somewhat resembling 
 that of the sinuses of the dura mater. The spermatic veins perforate the tunica albu- 
 ginea on the inner side of the epididymis, not opposite that body. They are soon joined 
 by the veins of the epididymis, so as to form a plexus, which communicates with the dor- 
 sal veins of the penis, and with the external and internal pudic veins. The spermatic 
 veins soon unite into five or six trunks, which pass upward in front of the vas deferens, 
 and, together with that caneil and the spermatic artery, enter into the formation of the 
 spermatic cord. These veins are tortuous ; they divide, and anastomose so as to form 
 the spermatic venous plexus, which is often tlie seat of varicose dilatations. The veins 
 ascend through the inguinal ring and canal, and having reached the interior of the pel- 
 vis, they leave the vas deferens, accompany the corresponding spermatic artery along 
 the psoas muscle, and terminate either in the renal vein, or in the inferior vena cava of 
 their own side. 
 
 In some cases the right spermatic vein opens both into the renal vein and the inferior 
 cava. When there are two veins on one side, they communicate with each other by a 
 great number of transverse branches, and, before terminating, unite into a single trunk. 
 
 The name plexus pampiniformis is given to a plexus generally formed by the spermatic 
 veins before their termination : this plexus is more frequently found on the left than on 
 the right side, according to the observations of Meckel. 
 
 The spermatic veins sometimes communicate with some branches of the portal system. 
 
 The left spermatic vein passes under the sigmoid flexure of the colon, which may per- 
 haps account for the greater frequency of varicocele on the left side. 
 
 The ovarian veins accompany the arteries of the same name : they commence by sev- 
 eral sets of branches, viz., uterine branches, which communicate very freely with the 
 uterine sinuses ; ovarian branches, properly so called ; branches from the round ligaments ; 
 and, lastly, some from the Fallopian tubes. All these unite within the substance of the 
 broad ligaments, and pass vertically upward, without being at all tortuous : in some ca- 
 ses they form a plexus pampiniformis. 
 
 The ovarian veins, like the uterine veins, become much enlarged during pregnancy. 
 
 The Inferior Phrenic Veins. 
 
 These exactly follow the course of the inferior phrenic arteries, to each of which there 
 are two veins. 
 
 The hepatic veins do not in any way correspond to the artery of that name ; they form 
 a separate system, or, rather, they are connected with the portal venous system, of which 
 they may be regarded as an appendage. 
 
 The Poktal Ststem of Veins. 
 
 The system of the vena porta {vena portarum), or the portal system, constitutes a spe- 
 cial venous apparatus, appended to the general venous system, and representing by it- 
 self a complete circulatory tree, having its roots, trunk, and branches. The first, or ve- 
 nous portion of this system of veins, is arranged like the veins of the other parts of the 
 body, and has its roots of origin in the spleen and pancreas, and in the sub-diaphragmatic 
 portion of the alimentary canal ; while the second, or arterial portion, sends its branches, 
 like those of an artery, into the interior of the liver. 
 
 The hepatic veins, which perform the functions of ordinary veins in reference to the 
 second or arterial portion of the vena portae, connect the system of the vena portae with 
 the general venous system. 
 
 The Branches of Origin of the Vena PortcB. 
 
 The branches of origin of the vena portae {i, fig. 222) consist of all the veins which 
 return the blood from the sub-diaphragmatic portion of the alimentary canal, and also 
 from the spleen and pancreas. They correspond to the branches of the coeliac axis, 
 
THE VENA PORTiE. 
 
 M9 
 
 with the exception of the hepatic artery ; they unite FigL a». ' 
 
 into three trunks, the great mesenteric (a), small mes- 
 enteric (b), and splenic (c) veins. 
 
 These veins are arranged like venae coraites to 
 the corresponding arteries. 
 
 The Great and Small Mesenteric Veins. — The intes- 
 tinal or mesenteric veins commence just as the ar- 
 teries terminate, by two layers of vessels, viz., a 
 sub-serous layer, the vessels of which ramify be- 
 neath the peritoneum, and a deep layer, formed by 
 the vessels of the coats of the intestinal canal. These 
 small vessels unite into anastomotic meshes, which 
 always lie subjacent to the arterial network, and 
 which terminate in larger branches, and thus con- 
 stitute a series of veins corresponding to the arter- 
 ies of the intestine. The right colic veins {d d) and 
 the veins of the small intestine (shown cut short at 
 e) terminate, the one in the right and the other in 
 the left side of the superior mesenteric or great mes- 
 araic vein (a) : this vein, in the early periods of in- 
 tra-uterine life, receives the omphalo-mesenteric vein, 
 a branch which corresponds to the omphalo-mesen- 
 teric artery, and commences upon the vesicula um- i 
 bilicalis ; the artery and the vein disappear about 
 the third month of utero-gestation, but the vesicle remains for a longer period. On the 
 other hand, the left colic veins (/) enter the inferior mesenteric or small mesaraic vein (J) : 
 this vessel forms the continuation of the superior hemorrhoidal veins {g), which commu- 
 nicate very freely with the middle and inferior hemorrhoidal branches of the internal 
 iliac vein. 
 
 The splenic vein (c), which is proportionally larger than the artery, arises in the cells 
 of the spleen by a great number of roots, which gradually unite in the hilus of that organ, 
 and form the same number of branches as there are arteries, each coming from a dis- 
 tinct compartment of the organ. All these branches soon unite into a single trunk, 
 which passes across to the right side behind the pancreas, and, therefore, behind the 
 splenic artery, which it accompanies without being tortuous : it is one of the branches 
 immediately concerned in forming the trunk of the vena portae. During its course, the 
 splenic vein receives the venous vasa brevia {h h) from the stomach. 
 
 The inferior mesenteric vein opens into the splenic ; so that there are only two venous 
 trunks, the union of which constitutes the vena portae, viz., the splenic and the great or 
 superior mesenteric. 
 
 The Vena Portce. 
 
 The trunk of the vena porta (i) is formed by the union of the splenic and superior mes- 
 enteric veins at an acute angle, behind the right extremity of the pancreas, in front of the 
 Tertebral column, and to the left of the vena cava inferior. The vena portae is larger 
 than either of its two branches of origin, but is smaller than the two taken together. It 
 passes obliquely upward and to the right side ; and, after running for about four inches, 
 reaches the left extremity of the transverse fissure of the liver, where it terminates by 
 bifurcating. The following are its relations during its course : anteriorly it is covered 
 by the head of the pancreas, the second portion of the duodenum, the hepatic artery, the 
 biliary ducts, and the lymphatics of the liver, and also by some branches from the hepatic 
 plexus of nerves ; posteriorly it is covered by that portion of peritoneum which dips be- 
 hind the vessels of the liver into the foramen of Winslow, to line the sac of the great 
 omentum. By this foramen it is separated from the inferior vena cava, the direction of 
 which it crosses at a very acute angle. 
 
 The two branches into which the vena porta? divides in the transverse fissure of the 
 liver separate so widely from each other, that they seem to form a trunk, at right angles 
 to which the vena portae itself is attached. Some anatomists apply the term sinus of the 
 vena porta to that portion of the vein which is situated in the transverse fissure ; that part 
 of the vein which adheres to the liver is more commonly called the hepatic portion of the 
 vena portae, to distinguish it from the free and floating part, which is named the abdom- 
 inal portion. 
 
 The two divisions of the vena portae pass horizontally each towards the correspond- 
 ing lobe of the hver ; they soon divide and subdivide into diverging branches, which sup- 
 ply all the granules or lobules of the liver. The branches of the vena portae are accom- 
 panied by the ramifications of the hepatic artery and biliary ducts. The capsule of Glis- 
 son, or the fibrous coat of the liver, is reflected upon them, and forms a common sheath 
 for them. (See Liver.) 
 
 Before birth, the hepatic portion {p, fig. 164) of the vena portae receives, besides the 
 
v|690 ANGEIOLOGY. 
 
 abdominal portion of the same vein, the umbilical vein (u), which is obliterated soon after 
 birth. Nevertheless, I once found it perfectly permeable in an adult.* 
 
 Before birth the ductus venosus (d) extends from the hepatic portion of the portal vein 
 to the vena cava inferior, between which and the vena portae it establishes a direct com- 
 munication. This hepatic portion might> therefore, be named the confluence of the veins 
 of the liver. 
 
 The Hepatic Veins. 
 
 The capillary radicles of the hepatic or supra-hepatic veins commence in the capillary 
 divisions of the vena portae, and, gradually uniting into larger and larger branches, con- 
 verge towards the posterior border of the liver, or, rather, towards the fissure for the 
 vena cava inferior, at which point they terminate by an indefinite number of small 
 branches, named the small hepatic veins, which open all along the fissure ; and also by two 
 principal trunks, the great hepatic veins, which end in the vena cava immediately before 
 It passes into the opening in the diaphragm. One of these great hepatic veins comes from 
 the right lobe, and the other from the left lobe of the liver. 
 
 The vein of the left side often receives a great number of branches from the right lobe 
 of the liver, and is larger than the vein of the right side. 
 
 The vena cava inferior is always dilated into a large ampulla opposite the openings of 
 the hepatic veins. 
 
 It follows, from the previous description, that, in the liver, the branches of the hepatic 
 veins and those of the vena portae run directly across each other, since the latter diverge 
 from the centre of the organ towards its right and left extremities, while the former con- 
 verge from the anterior towards the posterior border. 
 
 Moreover, the branches of the hepatic veins are unaccompanied by other vessels, and 
 are in direct contact with the tissue of the liver ; while those of the vena porta; are sep- 
 arated from it by the capsule of Glisson, and are accompanied by the ramifications of the 
 artery, the nerves, and the hepatic ducts. 
 
 I shall farther remark, that although the hepatic veins gradually unite, like other veins, 
 into branches, which decrease in number, but increase in size, they most of them receive 
 besides, during their course, a multitude of capillary vessels, the inter-lobular hepatic 
 veins, from the neighbouring lobules ; so that their internal surface is perforated with in- 
 numerable foramina. 
 
 The cribriform structure of their internal surface is therefore a peculiar characteristic 
 of all the hepatic veins [except the very large ones], and enables us always to distinguish 
 them from the branches of the vena portae. 
 
 Lastly, the capillary communication between the extremities of the vena portse and 
 hepatic veins is extremely free, as may be shown even by very coarse injections. 
 
 AH the veins of the portal system are without valves,t and they can therefore be in- 
 jected with the greatest ease from the trunks towards the extremities. An injection 
 thrown in towards the intestine penetrates very readily into the interior of the alimentary 
 canal, so that the minute branches of the vena portae appear to open at the apex of each 
 villus. This can be made evident by throwing mercury into the vena portae, and then 
 forcing it on by an ordinary injection ; drops of the mercury will then be seen in the 
 open mouth of each villus.J 
 
 The system of the vena portas is not so completely isolated from the general venous 
 system as is commonly stated. It always communicates with branches of the iirtemal 
 iliac veins by means of the middle hemorrhoidal veins, and communicating branches 
 with the renal veins have also been noticed ; and hence injections of the vena cava in- 
 ferior always enter in a greater or less degree into the veins of the portal system. 
 
 The Common Iliac Veins. 
 
 The common iliac veins (n n, fig. 222) correspond exactly to the arteries of the same 
 name ; they commence opposite the sacro-vertebral articulation by the junction of the 
 internal and external iliac veins, and terminate by uniting at an acute angle to form the 
 vena cava inferior or ascendens, the point of union being opposite the articulation of the 
 fourth and fifth lumbar vertebrae, to the right side of, and a little below, the bifurcation 
 of the aorta. 
 
 The common iliac veins hare the same relation to the lower extremities that the 
 brachio-cephalic veins bear to the upper ; and as the right brachio-cephalic vein is shorter 
 and more vertical than the left, so also is the right common iliac vein shorter and mere 
 vertical than the left. 
 
 The relations of the common iliac veins with the corresponding arteries are remarkable, 
 inasmuch as they are placed between these vessels and the vertebral column. The 
 right common iliac vein is situated to the outer side of and behind the corresponding ar- 
 
 * Anat. Pathol., livraison 17. 
 
 t M. Bauer says that he has seen valves in the venous vasa brevia of the stomach ; I have never been able 
 to discover them. 
 
 t [The escape of the mercury is due to rupture of the bloodvessels. In tlie villi, the minute branches of 
 the vena portae commence la t!',t ciijiillary network described and figured at page 36!).] 
 
THE INTERNAL ILIAC VEIN, ETC. %9i 
 
 leiy, and is parallel to it ; while the left common iliac is situated on the inner side, and 
 behind the corresponding artery, and is covered by its lower part. At the point where 
 the left common iliac vein joins the vena cava inferior, it is also crossed obliquely by ihe 
 right common iliac artery. It follows, therefore, that the left common illiac vein is 
 covered, and may be compressed by both common iliac arteries, while the right common 
 iliac vein cannot be compressed by either of them, and probably this is partly the reason 
 why anasarca of the left lower extremity is more common than in the right extremity 
 m atonic diseases. 
 
 The right common iliac vein receives no collateral branch ; the left common iliac (n, 
 fig. 223) is joined by the middle sacral vein (h). 
 
 The middle sacrai vein is situated in the median line, and its size depends upon that of 
 the artery of the same name ; it belongs to the rachidian veins, with which it will be 
 described 
 
 The Internal Iliac Vein. 
 
 The internal iliac or hypogastric vein exactly represents the internal iliac artery, on the 
 inner side of which it is situated, separated from it, however, by a very thin fibrous 
 layer, which holds it down against the walls of the pelvis. 
 
 The internal iliac vein receives the venae comites of the branches of the internal iliac 
 artery, the umbilical arteries in the foetus alone being excepted ; for their satellite vein, 
 the umbihcal vein, which is £dso peculiar to the foetus, terminates in the hepatic portion 
 of the vena portae, as we have already seen. 
 
 The internal iliac vein, therefore, receives the blood returned from the parietes of the 
 pelvis, from the organs contained within the cavity of the pelvis, and from the external 
 genitals. There are always two veins for each artery ; but the two unite into a single 
 vein at their point of termination in the principal trunk. 
 
 The veins belonging to the parietes of the pelvis, viz., the gluteal, obturator, and sciatic 
 veins, are arranged precisely like the corresponding arteries. The ilio-lumbar and lateral 
 sacral veins {i,fig. 223) form part of the rachidian system, which will be specially described. 
 
 The veins belonging to the genito-urinary organs present a plexiform arrangement 
 both in their trunks and in their roots, which deserves particular attention. 
 
 Some of the venous plexuses of the pelvis are found both in the male and female, as 
 the hemorrhoidal, while some are peculiar to one or the other sex, as the vesico-prostatic 
 and the plexuses of the penis to the male, and the vaginal and uterine plexuses to the 
 female. 
 
 The Hemorrhoidal Veins and Plexuses. 
 The hemorrhoidal veins and plexus form a venous network, surrounding the lower end 
 of the rectum. They are formed by the superior hemorrhoidal veins, which form the com- 
 mencement of the inferior mesenteric, and by the middle and inferior hemorrhoidal veins, 
 which are branches of the internal iUac. We ought to notice in particular the sub-mu- 
 cous venous network near the anus. The plexus formed by it is analogous to that found 
 in all other mucous membranes ; its vessels are liable to become varicose, a condition 
 which constitutes the greater number of hemorrhoidal tumours. 
 
 The Pelvic Veins and Plexuses in the Male. 
 
 Preparation. — Introduce one injection-pipe into the corpus cavernosum, and another into 
 the glans penis, and then push an injection simultaneously into both of them, and also 
 into the crural vein. 
 
 The superficial scrotal veins tenninate partly in the superficial veins of the perinseum, 
 and partly in the external pudic branches of the femoral vein ; they communicate with 
 the superficial veins of the under surface of the penis. 
 
 The Vesical Veins, or Vesico-prostatic Plexus. — The prostate gland and the neck ol the 
 bladder are covered by a very complicated plexus of veins, which become exceedingly 
 developed in chronic inflammation of the bladder ; it receives the superficial veins of the 
 penis, and gives off the vesical veins. 
 
 This plexus, which communicates with the hemorrhoidal plexus behind, is supported 
 by a very thick fibrous layer, which is continuous with the pelvic fascia, and which lim- 
 its the degree of dilatation of the veins of the plexus in the same way as the dura mater 
 limits the dilatation of the sinuses contained between its layers. 
 
 The Veins and Plexuses of the Penis. — The veins of the penis are divided into a superfir 
 cial and deep set, the former representing the sub-cutaneous veins of the limbs. They 
 commence in the skin of the prepuce, and run backward along the upper and lower sur- 
 faces of that organ. The superior are called the dorsal veins of the penis ; they commu- 
 nicate freely with each other by large branches ; most of them run beneath the arch of 
 the pubes, between it and the corpus cavernosum, passing through some openings or 
 fibrous canals in the sub-pudic ligament, which have the effect of keeping the veins al- 
 ways open ; they end by assisting in the formation of the prostatic plexus. These veins 
 communicate freely with the deep veins, especially opposite the junction of the two crura 
 
 4 G 
 
602 ANGEIOLOGY. 
 
 of tHfe corpus cavemosum : this communication is proved by the fact that the superficial 
 vessels are always filled when the injection is thrown into the deep veins. 
 
 The areolar tissue of the corpus cavemosum and that of the corpus spongiosum may 
 be regarded as composed of a venous network or plexus at its maximum of development. 
 Branches proceed from this plexus, which correspond to the divisions of the internal 
 pudic artery, and follow the same course. 
 
 These veins, and the vesico-prostatic plexuses, are liable to become varicose ; hard 
 earthy concretions, called phlebolites, are also frequently found in them. 
 
 The Pelvic Veins and Plexuses in the Female. 
 
 The vesical, or vesico-urethral plexus of the female, is less developed than that of the 
 male, on account of the absence of veins corresponding to the superficial veins of the pe- 
 nis, which are represented by a few branches from the labia majora. This plexus commu- 
 nicates with the veins of the clitoris, and also very freely with the vaginal plexus behind 
 
 The vaginal plexus is a vascular network, extremely well developed, especially oppo- 
 site the orifice of the vulva, which is entirely surrounded by it with several series of cir 
 cular anastomosing veins : it communicates with the vesical plexus in front, and with 
 the hemorrhoidal plexus behind ; so that all the plexuses in the pelvis are involved in 
 the state of turgescence, which a.ccompanies the phenomenon of erection in the female. 
 The radicles of this vaginal plexus commence in the mucous membrane of the vagina, 
 and especially in the erectile tissue surrounding the orifice of that canal ; some large 
 veins arise, in particular, from the bulb of the vagina, forming a true erectile apparatus, 
 which we have already described. (See Splanchnology, p. 320.) 
 
 The Uterine Plexus. — The veins contained in the substance of the walls of the uterus 
 do not present any trace of the tortuous arrangement of the corresponding arteries. In 
 order to obtain a satisfactory idea of them, they should be studied in a gravid uterus. 
 The uterine veins, like the uterine arteries, are then found along the sides and upper an- 
 gles of the organ ; opening into these veins are found larger venous canals, which run from 
 side to side through the substance of the uterus, and anastomose frequently with each 
 other. These venous canals are called the uterine sinuses, on account of their great 
 size during gestation, and from the dilatations presented by them at the confluence of sev- 
 eral secondary veins : they are also entitled to be so named from their structure, which 
 has some analogy with that of the sinuses of the dura mater, inasmuch as only the lining 
 membrane of the veins is prolonged into them ; their outer coat is formed by the proper 
 tissue of the uterus, and hence the walls of these veins are contractile. I have stated 
 elsewhere that, in reference to its veins, we may consider the uterus as consisting of an 
 erectile tissue with muscular walls ; it is scarcely necessary to add, that these sinuses 
 are unequally developed in different parts of the uterus, and that the point to which the 
 placenta has been attached may be recognised by the greater size of the adjacent ute- 
 rine sinuses. 
 
 The veins contained within the substance of the walls of the uterus do not open into 
 the uterine veins alone ; several of them terminate in the ovarian veins, which commu- 
 nicate freely with the uterine, and may, if necessary, supply their place. 
 
 The great size acquired by the uterine veins, both in the substance and on the surface 
 of the uterus, proves that the venous apparatus plays an important part in the intersti- 
 tial development of this organ. 
 
 Moreover, the size of the veins and venous plexuses belonging to all the genito-urinary 
 organs, and the essentially venous structure of such organs as are capable of being erect- 
 ed, prove that the venous system performs an essential part in the truly active phenom- 
 ena of erection. It is partly upon these anatomical and physiological arguments that I 
 have endeavoured to show the active part performed by the veins in all the great phe- 
 nomena of the economy, such as nutrition, secretion, inflammation, &c. 
 
 The pelvic veins are provided with a great number of valves, which prevent injections 
 from passing from the heart towards their extremities ; it ought to be remembered, that 
 the venous plexuses of the pelvis establish a very important and verv free communica- 
 tion between the veins of the right and left sides of the body. 
 
 The Deep Veins of the Lower Extremity. 
 The veins of the lower extremities, like those of the upper, are divided into the deep 
 veins or venae comites of the arteries, and the superficial veins. 
 
 The Plantar, Posterior Tibial, Peroneal, Dorsal, interior Tibial, and Pop 
 
 liteal Veins. 
 The external and internal plantar veins unite to form the posterior tibial, which accom- 
 panies the artery of that name, and soon joins the peroneal vein, to constitute the tibio- 
 peroneal vein : again, the anterior tibial vein, which commences by the vena dorsalis pedis, 
 perforates the upper part of the interosseous ligament, joins the tibio-peroneal vein, and 
 in this way forms the popliteal vein Up to this point there are two venae comites for 
 each artery, one of the veins being placed on each side of the artery, across which thev 
 
THE FEMORAL VEIN, ETC. 608 
 
 very frequently send communicating branches. The peroneal veins are generally larger 
 than the posterior tibial, and receive all the muscular veins from the posterior and out«»- 
 tegions of the leg. 
 
 Commencing with the popliteal, there is only one vein for the main artery of the 
 limb ; but the arteries of the second and third order always have two veins. 
 
 The popliteal vein is situated in the popliteal space, behind and in contact with the ar- 
 tery. Its coats are remarkably thick, so that when cut across it remains open, and in 
 the dead body has been sometimes mistaken for the artery. Below, and opposite the 
 articulation of the knee, the vein is situated immediately behind the artery ; above the 
 joint it is behind, and a little to the outer side. 
 
 The popUteal vein receives the large bundles of veins, the sural veins, from the gas 
 trocnemius muscle : they are remarkable ft)r the number of their valves ; also the articu- 
 lar veins, and generally the external saphenous vein. I have seen a small vein having 
 very numerous valves, and being analogous to the collateral venous canals of which I 
 have already spoken, extend from the upper part of the anterior tibial to the middle of 
 the popliteal vein. 
 
 The Femoral Vein. 
 
 The femoral vein, like the artery of that name, is bounded below by the ring in the 
 tendon of the adductor magnus, and above by the crural arch ; it has different relations 
 with the femoral artery in various parts of its course : thus, below, it is on the outer 
 side of the artery ; higher up, it is situated behind that vessel ; lastly, from the entrance 
 of the vena saphena interna to the crural arch, it is placed to the inner side of the artery, 
 and is in close contact with the posterior part of the opening for the femoral vessels ; so 
 that femoral hemiae descend in front of the vein, but not of the artery. The femoral vein 
 is single, like the artery ; nevertheless, there are one or two collateral venous canals, 
 which run parallel with the lower half, or lower two thirds of that vein ; some commu- 
 nicating branches from the internal saphenous vein, and some muscular branches, open 
 into these venous cauEds, which are always abundantly supplied with valves. 
 
 The femoral vein receives all the branches corresponding to the divisions of the fem 
 oral artery, excepting the external pudic veins and the cutaneous veins of the abdomen, 
 which terminate in the internal saphenous vein. 
 
 The great deep vein (profunda) opens into the femoral about ten or twelve lines be- 
 low the crural arch. 
 
 The External Iliac Vein. 
 
 The external iliac vein is bounded below by the femoral arch, and terminates at the up- 
 per part of the sacro-iliac symphysis by uniting with the internal iliac vein ; it has the 
 same relations as the artery, and is placed behind and to the inner side of that vessel, 
 excepting over the os pubis, where it is exactly to the inner side of the artery. In one 
 case I found the left common iliac receiving the right internal iliac, so that the right ex- 
 ternal iliac was prolonged into the vena cava. 
 
 The external iliac receives the epigastric and the circumflex iliac veins. These two 
 veins are double, but each pair unites into a single trunk, as it is on the point of open- 
 ing into the external iliac vein. 
 
 All the deep veins of the lower extremity, excepting the external iliac, are provided 
 with valves. There are four in the deep femoral, the same number in the popliteal, and 
 many more in the tibial and peroneal veins ; the mouths of all the small veins which 
 open into them are provided with a pair of valves. 
 
 The Superficial Veins of the Lower Extremity. 
 
 The superficial veins of the lower extremity are much less numerous than those of 
 the upper, and all terminate in two trunks, viz., the internal saphenous vein and the exter- 
 nal saphenous vein. 
 
 As in the hand, they are all situated upon the dorsal region of the foot. All the col- 
 lateral veins of the toes enter the convexity of a venous arch, which is more regular and 
 constant than that in the hand, and which is placed on the fore part of the metatarsus. 
 From the inner end of this arch is given off a large branch, named the internal dorsal 
 veir of the foot, which is the origin of the internal saphenous vein ; the outer extremity 
 also gives off a somewhat smaller branch, called the external dorsal vein of the foot, which 
 forms the commencement of the external saphenous vein. 
 
 The Internal Saphenous Vein. 
 The internal or great saphenous vein (saphena interna, s, in the representation of the 
 superficial nerves of the leg) is a collateral vein gf the femoral venous trunk, and is con- 
 tinuous with the internal dorsal vein of the foot. The last-mentioned vein commences 
 at the inner extremity of the dorsal venous arch of the foot, into which the collateral 
 veins of the great toe open ; it runs along the dorsal surface of the first metatarsal bone 
 and the corresponding part of the tarsus, and receives, during its course, a deep branch 
 from the internal plantar vein and all the superficial veins of the internal olantar region, 
 
604 ANGEIOLOGY. 
 
 and particularly the internal calcaneal vein, which is sometimes large, and which, in cer- 
 tain cases, does not terminate in the saphenous vein until it has reached above the in- 
 ternal malleolus, around the posterior border of which it turns. The internal saphe- 
 nous vein succeeds to the one just described ; it is reflected upward in front of the 
 internal malleolus, and continues to ascend upon the inner surface, then along the pos- 
 terior border of the tibia, and upon the back of the internal tuberosity of that bone and 
 the internal condyle of the femur. In this place it is situated on the inner side of the 
 tendons of the semi-tendinosus, gracilis, and sartorius ; it then inclines forward, descri- 
 bing a slight curve, with its concavity directed forward ; ascends along the anterior bor- 
 der of tfie sartorius, and crosses obliquely over the adductor longus ; having arrived at 
 the saphenous opening in the fascia lata, about eight or ten inches below Poupart's lig- 
 ament, it immediately curves backward, passes through that opening, and enters into 
 the femoral vein, just as the vena azygos enters into the superior vena cava, that is to 
 say, it describes a loop having its convexity directed downward. Several lymphatic 
 glands are found near this curve. 
 
 Relations. — The internal saphenous vein is separated from the skin by a very thin 
 fibrous layer, the superficial fascia, and is in relation with the internal malleolus, the 
 tibia, the tibial origin of the soleus, the tendons of the semi-tendinosus, gracilis, and sar- 
 torius, with the last-named muscle itself, and with the adductor longus. It is accompa- 
 nied by the internal saphenous nerve, from the knee down to the internal malleolus. 
 
 During its course it receives all the sub-cutaneous veins of the thigh, most of the sub- 
 cutaneous veins of the leg, the sub-cutaneous veins of the abdomen, the external pudic 
 veins, and several communicating branches from the deep veins. 
 
 The sub-cutaneous femoral veins of the back of the thigh sometimes unite into one rath- 
 er large trunk, which appears like a second internal saphenous vein ; it runs parallel with 
 the regular vein, and enters it at a greater or less distance from its termination. I have 
 met with an anterior superficial vein which commenced around the patella, ascended 
 vertically along the anterior region of the thigh, and might be regarded as a third.saphe- 
 nous vein. In one case of this kind, these three saphenous veins, viz., the anterior, 
 posterior, and internal, entered separately into the femoral vein, or, rather, into a dilata- 
 tion in which the internal saphenous vein terminated. 
 
 The internal saphenous vein often presents the following arrangement : opposite the 
 lower part of the leg, or at the lower end of the thigh, it divides into two equal branches 
 which pass upward, communicate with each other by transverse branches, and unite af- 
 ter running a variable distance ; in these cases the two branches represent a very elon- 
 gated ellipse. I have even seen this arrangement in both the thigh and leg of the same 
 subject, that is to say, the saphenous vein divided into two branches in the leg, which 
 united opposite the internal tuberosity of the tibia, and again divided in the thigh. 
 
 It is not uncommon to find a venous network supplying the place of the internal saphe- 
 nous vein in the thigh. 
 
 The sub-cutaneous abdominal veins should be arranged among the superficial and sup- 
 plementary veins, although there is a small artery, the superficial epigastric, which cor- 
 responds to them. There are three or four of these veins, which are joined by one from 
 the gluteal region ; they open sometimes by a common trunk, sometimes by three or 
 four distinct trunks, into the internal saphenous, just as that vein is passing through the 
 fascia lata. In a case of obliteration of the vena cava I found these veins very large, 
 and prolonged over the thorax into the axilla, where they anastomosed with the cuta- 
 neous branches of the intercostal and thoracic veins. In a case in which the umbilical 
 vein was persistent, the right and left internal saphenous veins were tortuous, and as 
 large as the little finger.* 
 
 The internal saphenous also receives the external pudic veins ; and I have seen it joined 
 by the obturator vein, which commenced by a common trunk with the epigastric. 
 
 The communicating branches of the internal saphenous with the deep veins are very nu- 
 merous, and should be studied in the foot, the leg, and the thigh. The origin of the in- 
 ternal saphenous vein gives off a branch, which communicates with the internal plan- 
 tar vein. 
 
 Along the leg several other branches exist, which establish a communication between 
 the internal saphenous and the posterior tibial veins ; these branches perforate the tib- 
 ial origins of the soleus muscle. 
 
 There is a very remarkable communication between the anterior tibial and internal 
 saphenous veins in the middle third of the leg, by means of a branch which proceeds 
 from the anterior tibial vein in front of the fibula, becomes sub-cutaneous, is reflected 
 inward and upward between the fascia of the leg and the skin, and terminates in the in- 
 ternal saphenous. 
 
 Again, an inferior, internal, articular vein enters the internal saphenous. 
 
 Lastly, the anastomoses in the thigh, between the deep and the superficial veins, aiu 
 less numerous than those in the leg ; at most we only find two such describing loops, with 
 the concavity directed upward. 
 
 * Anat. Path., liv. xviii. 
 
 1 
 
THE VEINS OF THE SPINE. #11$ 
 
 Valves. — The number of the valves appears to me variable : I have counted six along 
 the internal saphenous, but at other times I have not found more than two or four. 
 There is a greater number of valves in this vein in the thigh than in the leg. 
 
 The External or Posterior Saphenous Vein. 
 
 The external saphenous vein (la peroneo-malleolaire, Chauss. ; see figure of nerves ot 
 .eg), smaller and much shorter than the internal saphenous, is a branch of the popliteal 
 vein ; it forms a continuation of the external dorsal vein of the foot, vi'hich commences 
 from the outer extremity of the dorsal venous arch ; it passes behind the peroneo-tibial 
 articulation, crossing it from before backward ; it receives, as it runs outward, a grea< 
 number of branches, the chief of which come from the external plantar region ; also an 
 external calcaneal vein, which is sometimes of considerable size, and comes from thr 
 outer side of the os calcis ; the vein then runs along the outer border of the tendo Achil- 
 lis, and crosses it at a very acute angle, to reach the middle line of the posterior aspect 
 of the leg : conmiencing at this point, it passes directly upward, crosses the internal 
 popliteal nerve, and terminates in the popliteal vein between the internal and external 
 popliteal nerves, between the two heads of the gastrocnemius, and by the side of the in- 
 ternal inferior articular vein. 
 
 In some subjects the external saphenous, at the moment when it bends to dip into 
 the pophteal space, gives off an ascending vein, which runs along the posterior border 
 of the semi-membranosus muscle, as high as the upper third of the thigh, where it then 
 turns forward to open into the internal saphenous, or one of the branches of that vein, 
 immediately below its opening into the femoral. 
 
 Relations. — The external saphenous vein is covered by the superficial fascia, which 
 separates it from the skin, and it covers the externeil saphenous nerve, from which it is 
 separated by a layer of fascia ; it crosses this nerve twice, being at first situated to the 
 inner side, then to the outer side, and again on the inner side of the nerve. 
 
 The external saphenous vein communicates with the deep veins only, behind the ex- 
 ternal malleolus, and upon the dorsum of the foot. 
 
 This vein has only two valves, one of which is situated immediately before its open- 
 ing into the popliteal vein. 
 
 Such are the veins of the lower extremity. The analogy which exists between the in- 
 ternal dorsal branch of the foot and the cephalic vein of the thumb ; between the exter- 
 n£il dorsal branch and the vena salvatella ; between the external saphenous and the ra- 
 dial and cephalic veins ; between the internal saphenous and the ulnar and basilic veins, 
 cannot be doubted. There is no branch in the lower extremity analogous to the median 
 vein. 
 
 THE VEINS OF THE SPINE. 
 General Remarks. — The Superficial Veins of the Spine. — The Anterior Superficial Spinal 
 Veins, viz., the Cheater Azygos — the Lesser Azygos — the Left Superior Vertehro-costals 
 — the Right Vertebro-costals — the Vertebro-lumbar — the Ilio-lumbar, and Middle and Lat- 
 eral Sacral — the Anterior Superficial Spinal Veins in the Neck. — The Posterior Superfi- 
 cial Spinal Veins. — The Deep Spinal or Intraspinal Veins — the Anterior Longitudinal, 
 and the Transverse Veins or Plexuses, and the Vein^ of the Vertebra — the Posterior and 
 the Posterior and Lateral Transverse Veins or Plexuses — the Medullary Veins. — General 
 Remarks on the Veins of the Spine. 
 
 The spinal or rachidian veins constitute a very important part of the venous system, 
 which has only recently been specially studied. 
 
 These veins differ, in many respects, from the spinal arteries, so that the description 
 of the one does not afford much assistance in the study of the other ; nevertheless, I 
 shall frequently have occasion to point out some remarkable analogies between these two 
 sets of vessels. 
 
 The spinal veins are arranged most distinctly as venae comites and supplementary veins. 
 
 We shall divide them into the veins exterior to the spine or the superficial veins, and 
 the wms in the interior of the spinal canal, or the deep veins. 
 
 The Superficial Veins of the Spine. 
 The superficial veins of the spine may be subdivided into the anterior and posterior. 
 
 The Anterior Superficial Rachidian Veins. 
 The anterior superficial rachidian or spinal veins (see fig. 223) comprise the vena azy- 
 gos major, the vena azygos minor, the common trunk of the right superior intercostals, 
 that of the left superior intercostals, the vertebro-lumbar and ilio-lumbar veins, and the 
 lateral and middle sacral veins ; in the neck, the ascending cervical and the vertebral 
 veins. 
 
 The Greater Azygos Vein. 
 The vena azygos major (a «',^^.223) is a large single vein (dC^rof' without a rellow), 
 
606 
 
 ANGEIOLOGY. 
 
 Fig. 223. 
 
 situated along the vertebral column ; it commences {a') in the lumbar region, and termi- 
 nates at the upper part of the thorax by opening into the vena cava superior. 
 
 Its origin is subject to much variety. It very rarely arises from the trunk of the inle 
 rior vena cava itself, with which, however, it almost always communicates by small 
 branches. It generally forms the continuation of a series of anastomoses, which sur- 
 round the bases of the right transverse processes of the lumbar vertebrae, and which may 
 be called after some authors the ascending lumbar vein {b, on the right side) ; sometimes 
 it arises from the trunk of the last vertebro-costal, or the first vertebro-lumbar vein : we 
 rarely find a branch of origin from the renal or supra-renal veins. It often has two ori- 
 gins, one from the ascending lumbar, and the other from the first vertebro-lumbar, or 
 last vertebro-costal vein. The vena azygos, almost immediately after its origin, passes 
 from the abdominal into the thoracic cavity, through the aortic opening in the diaphragm, 
 ascends upon the right side of the bodies of the thoracic vertebrae, as high as the third 
 intercostal space, i. e., between the third and fourth ribs, 
 where it curves forward, forming, like the aorta, an arch, 
 which passes over and embraces the right bronchus, and opens 
 into the back of the vena cava superior, as that vein is enter- 
 ing the pericardium. 
 
 During its course the vena azygos is in contact with the 
 vertebred column, and is situated in the posterior mediasti- 
 num, on the right side of the aorta and of the thoracic duct 
 {t t), which runs parallel to it ; it lies in front of the right in- 
 tercostal arteries, and crosses them at right angles. It va- 
 ries in size, according to the number of branches which it re- 
 ceives, but gradually increases from below upward. 
 
 The question of the existence of valves in the vena azy 
 gos has given rise to much discussion. It appears to me to 
 be settled in the negative. 
 
 The vena azygos is joined in front by the right bronchial 
 vein and some oesophageal and mediastinal veins ; on the right 
 side by the eight inferior vertebro-costal veins (c c) of that side ; 
 and on the left by the lesser azygos (d) and the common trunk 
 (e) of the left superior intercostal veins. 
 
 Before opening into the superior vena cava, opposite the 
 third intercostal space, the azygos vein receives at its curve, 
 either by a common trunk, or by two or three separate branch- 
 es, the three superior right vertebro-costal veins, which some- 
 times enter the right brachio-cephalic vein, and sometimes 
 the vena cava superior, above where it is joined by the vena 
 azygos. In the last case they pass vertically upward ; in the 
 second they are directed almost vertically downward. 
 
 The Semi-azygos, or Lesser Jlzygos Vein. 
 
 The lesser azygos vein {d d,' azygos minor, semi-azygos) 
 may be regarded as the common trunk of the three, four, or 
 five inferior vertebro-costal veins (c' c') of the left side : it 
 opens into the great azygos vein. 
 
 It commences below {d') in as many different ways as the 
 great azygos vein, but it communicates with the renal vein 
 much more frequently. It runs upward upon the left of the 
 vertebral coliunn, approaches the median line, and opens into 
 the great azygos at a different height in different subjects. It 
 joins the great azygos either at right angles or obliquely, 
 passing behind the thoracic duct. The lesser azygos vein 
 may be regarded as the left branch of origin of the greater azy- 
 gos : sometimes it is extremely large ; in that case the great- 
 er azygos is directly continuous with it, and the right branch 
 is very small. 
 
 The lesser azygos vein is joined by the four or five inferior 
 vertebro-costal veins (c' c') of the left side. It also frequent- 
 ly receives the common trunk of the superior vertebro-costal 
 veins, which might be said to form a superior lesser azygos 
 vein. 
 
 The Left Superior Vertebro-costal Veins 
 The common trunk (e) of the left superior intercostal veins (//) might be called the 
 left superior lesser azygos, for it has the same relation to these veins that the lesser azy- 
 gos has to the inferior intercostals of the same side. It runs downward upon the left 
 of the vertebral column, increasing in size as it approaches its termination, which is 
 
THE INTERCOSTAL VEINS, ETC. 60T 
 
 either near the end of the lesser azygos, or in the greater azygos. Not unfrequently the 
 common trunk of the left superior intercostals bifurcates and opens both into the lesser 
 azygos and into the left brachio-cephaUc vein. In some cases it terminates entirely 
 in the left brachio-cephalic vein : I have myself met with this disposition. I have seen 
 the left superior phrenic and the mediastinal veins enter the trunk of the lesser vena 
 azygos immediately before its termination. 
 
 The number of the left vertebro-costal veins which unite to form the lesser azygos 
 vein varies from three to seven ; when only three or four of the highest of these verte- 
 bro-costal veins end in it, the two or three lower ones enter directly into the greater 
 azygos vein. 
 
 General Remarks on the Vena Azygos Major. — This vein returns the blood of the right and 
 left vertebro-costal vems to the heart ; its presence is rendered necessary, first, in con- 
 sequence of the inferior vena cava not being able to receive any veins from the point 
 where it enters the groove in the liver to its termination in the right auricle ; and, sec- 
 ondly, because the superior vena cava is also unable to receive any veins while it is 
 within the pericardium. The greater azygos is, therefore, a supplementary vein, a true 
 collateral canal which supplies the place of the venae cavae, and receives all the veins 
 corresponding to the branches given off" by the aorta during this long course. These ob- 
 servations are, for the most part, applicable to all the azygos veins. 
 
 Anatomical Varieties of the Azygos Veins. — It would be both useless and tedious to no- 
 tice here all the varieties that have been observed in the distribution of the azygos veins. 
 M. Breschet has described six, but there are many more. The following is a very cu- 
 rious variety : the greater azygos occupies the median line of the dorsal portion of the 
 vertebral column, and is divided below into two equal branches, a right and a left, each 
 of which receives the three inferior vertebro-costal veins of its own sides ; all the other 
 vertebro-costal veins end directly in the greater azygos. 
 
 Another not less curious variety is the following : there are two equal and parallel 
 azygos veins, a right, which receives all the right intercostal veins, and a left, which re- 
 ceives till the left intercostals : the two main trunks communicate with each other oppo- 
 site the seventh or eighth dorsal vertebra by a very large transverse branch. 
 
 The Intercostal or Vertebro-costal Veins. 
 The intercostal or vertebro-costal veins of both sides (c c, c' c',ff) correspond to the in- 
 tercostal or vertebro-costal arteries, the distribution of which it is important to caU to 
 mind. We have seen that each of these arteries divides into two branches : an intercos- 
 tal branch, properly so called, intended for the intercostal spaces ; and a spinal branch, 
 the dorsal division of which terminates in the spinal muscles and the skin, while its ver- 
 tebral, or intra-spinal division, is distributed to the vertebrae, to the spinal cord, and to 
 its coverings. In like manner, the vertebro-costal vebis are formed by the junction of the 
 spinal branch, to which we shall presently return, and the intercostal branch. These 
 two sets of branches unite into a common trunk, the vertebro-costal vein, which passes 
 transversely along the groove on the body of each vertebra, receives some veins from 
 the bone in that situation, and enters at a right angle into the corresponding axygos vein. 
 
 The Lumbar or Vertebro-lumbar Veins. 
 
 In the lumbar region there are no azygos veins, and each vertebro-lumbar vein en- 
 ters separately, or by a common trunk, with its fellow of the opposite side, into the back 
 of the vena cava inferior. Not unfrequently two of the vertebro-lumbar veins of the 
 same side open by a common trunk ; and it is not rare to find the left superior vertebro- 
 lumbar vein enter the renal vein. 
 
 The vertebro-lumbar veins {g) are distributed very differently from the corresponding 
 arteries. Opposite the bases of the transverse processes there are a series of anasto- 
 motic arches, wliich together constitute, on each side, an ascending branch, called the 
 ascending lumbar vein {b b), which communicates above with the corresponding azygos 
 vein, and below with the ilio-lumbar veins, and which might be regarded as a lumbar 
 azygos vein. The trunks of the vertebro-lumbar veins proceed from this series of arches 
 to the vena cava ; and all the intra-spinal and dorsi-spinal veins terminate in it. 
 
 The Ilio-lumbar, Middle Sacral, and Lateral Sacral Veins. 
 
 The ilio-lumbar vein, which opens into the common iliac, is distributed like the artery 
 of that name ; it sometimes receives the last vertebro-lumbar vein : it is joined by the 
 great veins which emerge from the lower inter- vertebral foramina of the lumbar verte- 
 brae ; by the branch which is continuous in front of the fifth lumbar vertebra, with the 
 series of arches forming what may be called the lumbar azygos ; and, lastly, by a com- 
 municating branch from the lateral sacral veins. 
 
 The middle sacral and lateral sacral veins represent the azygos veins in the sacral re- 
 gion ; they are joined by all the dorsi-spinal branches passing out from the inter-vertebral 
 foramina, and end in the common iliac veins. 
 
 The middle sacral vein (A) often conmiences below by three branches, a median in 
 
ANGEIOLOGY. 
 
 front of the coccyx, and two lateral and anterior branches. One of these joins the ves- 
 ical plexus, while the other communicates with the hemorrhoidal veins, and establishes 
 a remarkable communication between the general venous system and the system of the 
 vena portae. 
 
 The middle sacral vein passes vertically upward, somewhere near the middle line, and 
 opens into the left common iliac vein {71) at a greater or less distance from its junction 
 with the right common iliac. I have seen it bifurcate above to enter both common iliacs. 
 
 During its course it is joined opposite each vertebra by some transverse, plexiform 
 branches, which establish a free communication between it and the lateral sacral veins, 
 and which receive some large branches from the bodies of the sacral vertebrae. These 
 transverse branches represent the vertebro-costal and vejrtebro-lumbar veins, which also 
 receive the veins which issue from the bodies of the vertebrae, through the foramina, 
 upon the inner surface of those bones. 
 
 The lateral sacral veins (i), of which there are always more than one on each side, are 
 continuous with the dorsi-spinal veins, which emerge from the anterior sacral foramina ; 
 there are generally two, a superior, which enters the common iliac vein, and an inferior, 
 which forms a very remarkable plexus, opposite the great sciatic notch, and ends in the 
 internal iliac vein, or in its gluteal and sciatic branches. 
 
 The Jlnterior Superficial Spinal Veins in the J^eck. 
 
 In the anterior cervical region we lind transverse plexiform branches (A) opposite each 
 vertebra, more particularly opposite the first and second ; these plexuses open partly 
 into the ascending cervical vein, which corresponds to the ascending cervical artery, 
 but principally into the vertebral vein, which is contained within the canal formed by 
 the series of foramina at the base of the transverse processes of the cervical vertebrae. 
 These plexiform branches, which cover the sides of the bodies of all the vertebrae, are 
 joined by the veins from the praevertebral muscles, by the articular veins, and by the 
 anterior osseous veins from the bodies of the corresponding vertebrae. 
 
 The vertebral veins and the ascending cervical veins may therefore be said to repre- 
 sent the azygos veins in the cervical region. 
 
 The Posterior Superficial Spinal Veins. 
 
 The posterior superficial spinal veins commence in the skin, and in the muscles of the 
 vertebral grooves : some of them closely accompany the arteries ; for example, those 
 that pass between the muscles of the vertebral grooves ; the others have a peculiar dis- 
 tribution, and require a special description. 
 
 These veins, which are called dorsi-spinales by MM. Dupuytren and Breschet, form 
 an exceedingly complicated network, the meshes of which surround the spinous process- 
 es and laminae, and the transverse and articular processes of all the vertebrae : these 
 meshes are more numerous in proportion as the injection is more perfect. 
 
 After a successful injection, we sometimes find along the summits of the spinous pro- 
 cesses, especially in the dorsal and cervical regions, certain median longitudinal veins, 
 from which the interosseous branches proceed. These latter run forward, on each side 
 of, and in contact with, the inter-spinous ligaments. Having reached the base of the 
 corresponding spinous process, they pass outward, opposite the intervals between the 
 laminae of the vertebrae, as far as the bases of the transverse processes, and then divide 
 into two branches : one of these ascends, and anastomoses with the descending branch 
 from the vein above ; while the other branch descends, and anastomoses with the as- 
 cending branch of the vein below. It follows, therefore, that around the transverse pro- 
 cesses and the laminae of the vertebrae there is a series of venous circles, which com- 
 municate, opposite each inter- vertebral foramen, with the veins contained in the interior 
 of the spine. 
 
 The posterior superficial spinal veins in the neck have a much more complicated ar- 
 rangement, and, indeed, form a plexus. Moreover, we generally find, between the com- 
 plexus and the semi-spinalis colli, two longitudinal veins, which appear to me to deserve 
 a jiarticular description, under the name of the posterior jugular veins. 
 
 The posterior jugular veins commence between the occipital bone and the atlas, pass 
 tortuously out from the interval between these bones, run downward and inward, and, 
 opposite the spinous process of the axis, the veins of the two sides anastomose by a 
 transverse branch. They then change their direction, pass downward and outward, and 
 having reached the lower part of the neck, turn forward, between the seventh cervical 
 vertebra and the first rib, and open into the back of the brachio-cephalic vein behind the 
 vertebral vein. The two posterior jugular veins are therefore arranged in the form of 
 the letter X. 
 
 The posterior jugular vein, which does not always exist, for its branches of origin 
 sometimes remain separate, seems to be inversely proportioned to the vertebral vein, 
 with which it communicates opposite each inter-transverse space. It has appeared to 
 me to communicate above with the deep occipital and the mastoid veins, with the veins 
 situated in the spinal caned, and with the interned jugular vein. Throughout the whole 
 
THE INTRA-SPINAL VEINS. OOII 
 
 01 Its course, it communicates freely, opposite each inter-vertebral foramen, with the 
 veins contained in the interior of the spinal canal, and with the vertebral vein. 
 
 The Deep Spinal or Intra-spinal Veins. 
 
 The veins in the interior of the spine comprise the proper veins of the spinal cord, and 
 the veins situated between the bones and the dura mater, which are subdivided into the 
 anterior and the posterior longitudinal veins or plexuses, and the transverse veins or plexus- 
 es ; the latter establishing a free communication between all four of the longitudinal 
 veins or plexuses, opposite each vertebra. 
 
 Before describing the veins situated between the bones and the dura mater, I must 
 state, in a few words, what is the arrangement of the proper arteries of the vertebras. 
 
 The spinal branches which are given off on each side of the body by the vertebral ar- 
 tery in the neck, by the intercostal arteries in the back, by the lumbar arteries in the 
 loins, and by the lateral sacral arteries in the pelvis, enter the spinal canal through the 
 several inter- vertebral foramina, and then each of them divides into an ascending and a 
 descending branch ; the ascending branch runs upward upon the lateral part of the body 
 of the vertebra above, and anastomoses with the descending branch of the spinal artery 
 above it, while the descending branch anastomoses with the ascending branch of the 
 artery below. Each of the anastomotic arches thus formed has its concavity directed 
 outward ; so that there is a series of arterial arches, united at their extremities, situ- 
 ated upon each side of the posterior surface of the bodies of all the vertebra. From the 
 convexity of each arch two transverse branches are given off, one running above and 
 the other below the small foramina upon the posterior surface of the body of the corre- 
 sponding vertebra. The cribriform portion of the bone is thus surrounded by the arte- 
 rial arches with their transverse branches ; and from all points of the polygon which 
 they form small arteries are given off, which penetrate into the substance of each ver- 
 tebra, and anastomose with the arterial twigs that enter the anterior surface of the body 
 of the vertebra. 
 
 The arrangement of these arteries gives a perfect idea of that of the veins known as 
 the anterior longitudiruU veins or plexuses, and of the transverse plexuses, which pass from 
 one to the other. 
 
 The ^Interior Longitudinal Intra-spinal Veins or Plexuses, the Transverse 
 PlexuseSy and the Proper Veins of the Bodies of the Vertebra. 
 
 Dissection. — Remove the arches of the vertebrae, and the spinal cord and its coverings. 
 The plexus may also be viewed from the front, by carefully sawing through the pedicles 
 and then removing the bodies of the vertebrae. 
 
 The anterior longitudinal plexuses, described by Chaussier, but still more correctly by 
 Breschet, form two venous trunks, named the great anterior longitudinal veins, extending 
 from the foramen magnum to the base of the coccyx, one on each side of the posterior 
 common vertebral ligament, and therefore upon the sides of the posterior surface of the 
 bodies of the vertebrae, and on the inner side of their pedicles. These veins, improperly 
 called vertebral sinuses, communicate together opposite each vertebra by a transverse 
 plexus, situated between the body of the vertebra and the posterior common ligament. 
 These longitudinal plexuses are less developed in the cervical and sacral regions. It is 
 probable that in the neck their place is supplied by the vertebral veins. 
 
 It would be in vain to consider these plexuses as having a distinct origin, course, and 
 termination ; the description given above of the distribution of the arteries is applicable 
 to the veins in every respect : thus, the venous plexuses are formed by a series of plex- 
 iform arches, which embrace the pedicles of each vertebra, have their concavity directed 
 outward and their convexity inward, and the extremities of which anastomose together 
 opposite the inter- vertebral foramina, where they communicate with the branches on the 
 outside of the spine, and assist in the formation of the vertebro-lumbar and vertebro- 
 costal veins, and, consequently, of the azygos veins. From the convexity of each arch 
 proceeds a transverse plexus, which goes to join with its fellow of the opposite side ; 
 and, just as we have seen that the transverse arteries extending from one arterial arch 
 to another give off branches to the bodies of the vertebrae, so, in like manner, the trans- 
 verse venous plexuses receive the veins which emerge from the body of each vertebra. 
 
 The arrangement of the veins or plexuses just described explains the alternate en- 
 largements and contractions observed in different parts of the anterior longitudinal plex- 
 uses. The rare interruptions described by M. Bresche( I believe to depend upon im- 
 perfect injections, which succeed so differently in different subjects. 
 
 The anterior longitudinal veins or plexuses cannot be regarded as sinuses, for they are 
 not contained in a fibrous sheath, like the veins of the dura mater, nor are they reduced* 
 merely to the lining membrane of the veins. Notwithstanding their extreme tenuity, 
 we can recognise an external coat, and the posterior common ligament does not covet 
 them behind. Nor is the term sinus more applicable to the transverse plexuses, although 
 they are situated between the bodies of the vertebrae and the posterior common ligament,. 
 for the ligament merely covers them without forming a sheath for them. 
 
 4H 
 
610 ANGEIOLOGY. 
 
 The Proper Veins of the Bodies of the Vertebra. — The foramina upon the posterior sux- 
 face of the body of each vertebra, which are generally proportioned to the size of the ver- 
 tebra, are principally intended for the proper veins of the bodies of their bones : the ar- 
 teries are much smaller, and though they enter by the same openings, they occupy but a 
 small part of their areas. These veins belong to that system of venous canals found in 
 the substance of bones, which we have already noticed as existing in the bones of the 
 cranium. Their chief varieties have been correctly described and delineated by M. Bres- 
 chet. These venous canals, which are more developed in the old than in young sub- 
 jects, occupy the centre of the body of the vertebra, and always run parallel to the up- 
 per and lower surfaces of the bone : they arise from all parts of the circumference of the 
 vertebra, communicating with the veins which enter by the foramina on its anterior sur- 
 face, and converge towards the principal foramen, or foramina, upon its posterior eis- 
 pect. They frequently enter a semicircular canal, which has its convexity directed for- 
 ward, and gives off from its concavity a venous canal, which opens directly into the 
 transverse plexus : the lateral veins of the body of the vertebra open into the extremities 
 of this semicircular canal ; while within the venous canals of the vertebrae, the veins are 
 reduced to their lining membrane, like the veins in the canals of the cranial bones. 
 
 The transverse plexuses, therefore, collect the blood from the bodies of the vertebra), 
 and transmit it to the anterior longitudinal plexuses. 
 
 The Posterior IntrU'Spinal Veins or Plexuses, and the Posterior and Lateral 
 Transverse Plexuses. 
 
 The posterior intraspinal plexuses, much smaller than the anterior, are situated one on 
 each side between the vertebral laminae and ligamenta subflava behind, and the dura 
 mater in front. These veins are rarely injected along the whole length of the spine, and 
 hence they sometimes appear to exist only in the dorsal region. They communicate op- 
 posite each vertebra, by means of posterior transverse plexuses, or by transverse veins. 
 They communicate with the anterior longitudinal plexuses by small lateral transverse 
 plexuses, which pass from behind forward. It follows, therefore, that the veins within 
 the spine, but external to the coverings of the cord, consist of four longitudinal plexuses, 
 all of which are connected by a transverse circular plexus opposite each vertebra. A 
 strict analogy may be said to exist between the sinuses of the cranium and the intra-spi- 
 nal plexuses ; an analogy which did not escape the notice of the ancients, as the com- 
 mon application of the term sinus by them to the veins of the cranium and to those of the 
 spine would seem to indicate. Thus, in the cranium we find certain longitudinal sinus- 
 es, that is, those which run from before backward, viz., the superior longitudinal sinus, 
 the straight sinus, and the posterior occipital sinuses ; also, the superior and inferior pe- 
 trosal sinuses, the cavernous sinuses, and the right and left lateral sinuses. The former 
 set represent the posterior intra-spinal plexuses ; the latter correspond to the anterior in- 
 tra-spinal plexuses. 
 
 In the cranium we also find certain transverse sinuses, viz., the basilar or transverse 
 occipital sinuses and canals, and the coronary sinus, which exactly correspond to the 
 transverse plexuses, extending from one anterior intra-spinal plexus to the other. We 
 sometimes find two or three transverse venous plexuses in the basilar groove of the oc- 
 cipital bone. 
 
 Lastly, may we not compare the veins on the outer surfaces of the spine to the occipital, 
 frontal, and temporal veins ; and do not the veins passing through the posterior lacerated 
 foramen and the sphenoidal fissure, which we have regarded as representing the inter- 
 vertebral foramina (see Osteology), establish a communication between the veins on 
 the inside and those on the outside of the cranium, just as the veins which escape through 
 the inter-vertebral foramina connect together the superficial and the intra-spinal veins 1 
 
 The anterior and posterior deep spinal veins communicate with the superficial veins 
 of the spine at the inter-vertebral foramina so freely, that the circulation would not be 
 interfered with even if a considerable amount of obstruction existed. I have already 
 stated (see VERTEBRiE) that the diameter of the inter-vertebral foramina is in relation, 
 not with the size of the nervous ganglia, but rather with that of the veins, which estab- 
 lish a communication between the superficial and intra-spinal venous systems. 
 
 The Proper Veins of the Spinal Cord, or the Medullary Veins. 
 
 If we examine the pia mater of the spinal cord, even without having injected it, in the 
 body of a person who has died suddenly, as in that of a new-born infant after death from 
 asphyxia or apoplexy, the surface of the pia mater will be found covered by very tortu- 
 ous veins, which emerge from the posterior median furrow of the spinal cord. This ve- 
 nous network, which is spread over the whole surface of the cord, gives off opposite the 
 roots of each nerve a small vein, which runs directly between those roots, enters the 
 corresponding inter-vertebral foramen, is enclosed with the nerve in the sheath formed 
 by the dura mater, and having emerged from that sheath, opens into the large vein sit- 
 uated in the inter-vertebral foramen. 
 
 There is, therefore, this difference between the proper veins and arteries of the spinal 
 
THE LYMPHATIC SYSTEM. 811 
 
 cord, that the number of veins is equal to that of the nerves ; while the arteries are less 
 numerous, and enter the fibrous sheaths of the nerves only at intervals, and in propor- 
 tion as the preceding arteries are exhausted. Moreover, the anterior and posterior spi- 
 nal veins, like their corresponding arteries, may be regarded as belonging only to the up- 
 per part of the cord, and not as being intended to traverse its whole length. 
 
 General Remarks on the Veins of the Spine. 
 
 The veins of the spine maybe regarded, in reference to the general circulation, as es- 
 tablishing an unbroken communication between the veins of all parts of the trunk ; so 
 that we can suppose one of the venae cavae to be obliterated, without the venous circu- 
 lation being interrupted. The greater azygos itself, which is generally regarded as the 
 principal means of communication between the two venae cavae, is not, however, neces- 
 sary, when we consider the arrangement of the anterior and posterior spinal plexuses. 
 Thus, I have sometimes seen the inferior, and sometimes the superior vena cava oblit- 
 erated without any apparent increase in the diameter of the vena azygos, and, what will 
 perhaps be thought surprising, without oedema, either of the upper or lower extremities. 
 
 Supposing the vena cava ascendens to be obstructed from the entrance of the hepatic 
 veins down to the renal veins, the blood would then flow back by the vertebro-lumbar 
 veins into the plexuses contained within the spinal canal ; through these plexuses, it 
 would ascend to the vertebro-costal veins, from thence to the azygos veins, and through 
 them into the superior vena cava. 
 
 If all the jugular veins were obliterated, the venous circulation in the head would still 
 continue, and would be carried on through the spinal veins. I have tied the two exter- 
 nal jugular veins in a dog. The animal showed no sign of cerebral congestion : after 
 opening the body, I did not find any increase of size in the small veins which accom- 
 pany the carotid arteries, and which in those animals are naturally very smalL In this 
 case, the circulation was evidently carried on by means of the spinal veins. 
 
 THE LYMPHATIC SYSTEM. 
 
 Definition, History, and general View of the Lymphatic System. — Origin. — Course. — Tcrim- 
 nation and Structure of the Lymphatic Vessels. — The Lymphatic Glands. — Preparation oj 
 the Lymphatic Vessels and Glands. 
 
 The term lymphatic vessels is applied to certain transparent tubes provided with valves, 
 and conveying either lymph or chyle, which pass through small, rounded, glanduliform 
 bodies called lymphatic glands, and in all cases empty themselves into the venous sys- 
 tem, to which, indeed, they may be said to form an appendage. 
 
 From their tenuity and transparence, these vessels for a long time escaped the notice 
 of anatomists. The thoracic duct was discovered by Eustachius in 1565. The lac- 
 teals were discovered in 1622 by Gaspard Asellius, who, by a lucky chance, while seek- 
 ing quite another object, discovered certain vessels filled with chyle. In 1641, Pecquet 
 discovered the receptaculum chyli, and showed that the lacteals entered the thoracic 
 duct, and not the liver, as Asellius and all his contemporaries believed. 
 
 Rudbeck, Thomas Bartholin, and JolyfF dispute the honour of having discovered the 
 l)Tnphatic vessels, properly so called, in contradistinction to the lacteals or chyliferous 
 vessels. 
 
 Mascagni devoted a great part of his life to the study of the lymphatic system ; and 
 his work, ornamented by magnificent plates, is a monument of science, which should be 
 taken for a model by all who are engaged in anatomical inquiries. Lastly, within the 
 last few years, MM. Fohmann, Lauth, Lippi, Panizza, and Rossi have thrown light upon 
 some most important points in the anatomy of this system. 
 
 In describing this system of vessels, the lacteals, or the Ijntnphatics containing chyle, 
 have commonly been separated from the lymphatics, properly so called, or the vessels 
 containing lymph. This distinction, however, is not warranted by anatomy, for the two 
 sets of vessels are perfectly identical in structure. 
 
 The IjTnphatic system offers many analogies with the venous system ; but there ar 
 also no less remarkable differences between the two. 
 
 Like the venous system, it consists, as a whole, of afferent or converging vessels 
 which arise from all parts of the body, and run from the periphery towards the centre. 
 
 Like the veins, the lymphatics are divided into two sets : a srib-cutaneous set, which, 
 in general, accompanies the superficial veins of the limbs ; and a deep set, which follows 
 the course of the deep arteries and veins ; and, lastly, the lymphatics resemble the veins 
 in being provided with valves. 
 
 The lymphatics differ from the veins in passing through certain bodies improperly 
 called glands, which, at intervals, intercept their course. They differ from the veins, 
 also, in their arrangement ; for they do not successively unite into larger and larger 
 branches, and these into trunks, but they scarcely increase in size from their origin to 
 their termination ; and, though they communicate with each other by numerous anasto- 
 
6t$ ANGEIOLOGY. 
 
 moses, each of them follows, as it were, an independent course : lastly, the blood which 
 circulates in the veins is still, though indirectly, under the influence of the heart's ac- 
 tion, while the onward movement of the lymph is exclusively dependant upon the pari- 
 etes of the vessels. 
 
 Before proceeding to the special description of the lymphatics, we shall make some 
 general remarks upon the origin, course, and termination of these vessels. 
 
 Origin of the Lymphatics. 
 
 Tlie origin of the lymphatics, hke every point connected with the minute structure of 
 the tissues, is yet a new subject for inquiry.* 
 
 It has been said that the Ijmnphatics are continuous with the arteries, so that, accord- 
 ing to this hypothesis, the arteries are continuous with two kinds of vessels, viz., with 
 the lymphatics, which carry off the serum, and with the veins, which transmit the col- 
 oured part of the blood. The continuity of the arteries with the lymphatics has been 
 admitted, in consequence of its having been observed that injections thrown into the 
 arteries passed into the lymphatics. I have frequently seen this in injecting the spleen 
 and the liver ; but it was only when the injection was pushed in with great and contin- 
 ued force : so that it is possible, as thought by Hunter, Monro, and Meckel, that, in these 
 cases, some of the vessels had been ruptured, and the injection extravasated ; or, what 
 is still more probable, there may have been transudation through the pores of the tis- 
 sues. Microscopical observations show most distinctly that the arteries are continuous 
 with the veins ; but there is no fact to demonstrate the continuity of the arteries with 
 the lymphatics. 
 
 The origin of the lymphatics can be actually shovra only upon free surfaces, such as 
 the mucous membranes, the skin, the serous and synovial membranes, and the lining 
 membranes of arteries and veins ; so that, in the actual state of our knowledge, it might 
 be maintained that the lymphatic vessels arise exclusively from all the free surfaces. 
 
 All the lymphatics arise by a network of such tenuity that, when .injected with mer- 
 cury, the whole surface appears changed into a metallic layer. 
 
 About eight years since, having introduced at random a tube filled with mercury for 
 injecting the lymphatics into the pituitary membrane in a calf, I was astonished to find 
 the surface covered by a metallic pellicle : I repeated the experiment frequently, and 
 constantly found that the pellicle was not caused by extravasation, for the mercury ran 
 in determinate lines, forming plexuses of different kinds ; also that, to succeed in this 
 experiment, it was necessary to puncture the membrane very superficially, or the mer- 
 cury would run into the subjacent plexus of veins; and, lastly, that there was no com- 
 munication between that plexus of veins and the more superficial network, which I sus- 
 pected to consist of lymphatic vessels, for it exactly resembled the network of those 
 vessels in the peritoneum covering the liver. I ascertained that the same structure ex- 
 isted in the skin ; in the lingual, buccal, and vaginal mucous membranes ; in the con- 
 junctiva ; and, lastly, in the uterine mucous membrane of a sow which had lately lit- 
 tered. I showed this lymphatic network of the pituitary membrane in several of my 
 lectures ; and lately, having again examined the subject for the purposes of the present 
 work, I have ascertained that this network exists upon all the free surfaces, that it com- 
 municates with the lymphatics, and that it is possible to inject those vessels and the 
 lymphatic glands by introducing the pipe very superficially into the surfaces of these 
 membranes.! I may be permitted to observe, that it is only a few months since I be- 
 came acquainted with the splendid work of M. Panizza, of Pavia, upon the lymphatic ves- 
 sels of the testicles {Osservazioni Antropo-zootomico Fisiologiche, 1830) ; and with M. Foh- 
 mann's last very important memoir {Mimoire sur les Vaisseaux Lymphatiques de la Peau, 
 des Membranes Muqueuses, Sereuses, du Tissu Nerveux, ct des Muscles, 1833). 
 
 Origin of the Lymphatics from the Mucous Membranes. — The villi found upon the mu- 
 cous membrane of the small intestines contain, in their centre, a cavity, named the am- 
 pulla of lAeberkuhn, which I have seen in one instance filled with tuberculous matter. 
 {Anat. Pathol, \w. ii.) Still, I have never been able to discover any open orifice on the 
 summit of that villus.J Independently of these cavities within the villi, which are proper 
 to the system of lacteal vessels, the thin pellicle of the mucous membranes which can- 
 not be injected from the arteries or veins {vide p. 370), when carefully and very super- 
 ficially punctured by the pipe of a mercurial injecting apparatus, is covered by a metallic 
 pellicle. Panizza and Fohmann have proved that the membrane which covers the glans 
 penis has two sets of lymphatics : a superficial and a deep. M. Fohmann has figured, in 
 some very beautiful plates, the lymphatic network of the mucous membranes of the glans 
 penis, bladder, urethra, trachea, bronchi, oesophagus, stomach, ileum, and colon. This 
 network is so superficial, that the mercury appears almost uncovered ; it does not com- 
 
 * Do lymphatics commence in all parts of the body ? It is true that absorption is carried on in every part, 
 for absorption is one element of the process of nutrition ; but, as it can be effected by other vessels besides the 
 lymphatics, its occurrence in any part does not necessarily involve the presence of this peculiar class of vessels. 
 
 T These preparations were made by M. Bonami, my prosector, under my direction, with extreme skill, and 
 a zeal above all praise. 
 
 ', [For what is known conceming^ the structure of the villi, see note, p. 369] 
 
ORIGIN OF THE LYMPHATICS. 613 
 
 municate either with the arteries or the veins, but communicates freely with the lym- 
 phatic vessels. It was correctly delineated by Mascagni : according to that anatomist, 
 it covers all the intestinal villi, as with a sheath, and does not appear to have any open- 
 ings on the exterior. 
 
 Origin of the Lymphatics from the Skin. — Are the openings or pores so evident upon the 
 skin when viewed through a lens, and from which drops of sweat maybe seen to exude, 
 intended to serve the purpose both of exudation and absorption 1 or are there rather two 
 distinct kinds of orifices for these two functions 1 or, lastly, are these orifices altogether 
 unconnected with the absorbent vessels 1* 
 
 If we puncture the skin very superficially, so that the injecting pipe may enter imme- 
 diately below the epidermis, the mercury will be seen to run with great rapidity into 
 some very small vessels, and to form a metallic network, precisely like that already de- 
 scribed as existing in the mucous membranes ; from this layer proceed sub-cutaneous 
 lymphatics, which may be traced filled with mercury as far as the adjacent lymphatic 
 glands, or even beyond them. In order that this experiment may succeed, it is neces- 
 sary that the skin to be injected should be plunged into hot water. 
 
 I made the following experiment in order to detect, if possible, in the lymphatics of 
 the skin, the mercury absorbed during mercurial frictions. I caused two dogs to be 
 rubbed with mercurial ointment night and morning ; and, that the absorption might be 
 more complete, I enveloped their bodies in a frock made of skin. These animals died in 
 about eight days with gangrene of the gums ; but I could not find in any part the slight- 
 est trace of mercury, although the frictions were continued up to the period of their 
 death. 
 
 Origin of the Lymphatics from the Serous and Synovial Membranes. — The same results 
 as those above stated are obtained by injecting the serous and synovial membranes. 
 The portion of peritoneum covering the liver is generally chosen for injecting the l>Tn- 
 phatic network of serous membranes, because the tension and adhesion of the perito- 
 neum over the liver renders it more easy to inject. The same results may be obtained 
 by injecting the costal or pulmonary pleura, the tunica vaginalis, or the parietal and vis- 
 ceral portions of the arachnoid. 
 
 The synovial membranes may be injected with the greatest facility, either near the 
 cartilages, where they are more tense than in other parts, or upon the ligaments, to 
 which they adhere. 
 
 Origin of the Lymphatics from the Lining Membrane of the Veins and, Arteries. — ^The 
 lymphatic plexuses upon the lining membrane of veins and arteries have hitherto been 
 only partially displayed, but the analogy between these and serous membranes is so 
 close, that I have no doubt of their identity in this respect. I have, moreover, found the 
 lymphatic vessels of the aorta filled with blood in several cases of degeneration of the 
 coats of that vessel. 
 
 Origin of the Lymphatics in the Free Cellular Tissue. — In order to exhibit the origin of 
 the lymphatics in this situation, I injected coloured liquids, such as ink, into the sub- 
 cutaneous and inter-muscular cellular tissue in several animals, and I found the lym- 
 phatic vessels and the corresponding lymphatic glands of a jet-black colour. I made a 
 great number of experiments to induce absorption of mercury, by injecting it either into 
 the cellular tissue, or into a serous cavity ; but the metallic mercury always acted like 
 a foreign body, the mechanical effect of which produced more or less inflanunation, but 
 it was never absorbed. 
 
 I have found pus in both the superficial and deep lymphatics, and in the lymphatic 
 glands of the groin, after phlegmonous erysipelas and acute abscesses of the leg ; but it 
 is not proved that the presence of this pus was the result of absorption. It is more 
 probable that it had been produced by inflammation of the lymphatics themselves. 
 
 Although it is impossible to demonstrate, anatomically, the presence of lymphatics in 
 the free cellular tissue, it is most probable that that tissue, as well as the serous mem- 
 branes, with which it heis so many anedogies, is formed by this kind of vessels. Mas- 
 cagni stated that all the white tissues consist of lymphatic vessels, and that the lym- 
 phatic system forms the basis of the whole body. 
 
 From the preceding observations, it may be stated that, with the exception of the 
 lacteals which open upon the summits of the villi, + all the lymphatic vessels of free sur- 
 faces arise by an exceedingly delicate network ; M. Fohmann believes that all the lym- 
 phatics commence by a network of closed vessels.t 
 
 I have never been able to discover the l)Tnphatic networks, either in the nervous sub- 
 stance, in muscles, glands, or in the fibrous, cartilaginous, and osseous tissues. 
 
 * [These pores are the orifices of the ducts of the sudoriferous glands, which are imbedded in the true skin, 
 or the sub-cutaneous cellular membrane, and have no direct connexion with the lymphatics.] 
 
 + [Whether the lacteals commence in each villus by a network, or by free closed extremities, is not yet de- 
 termined ; but they form no exception to the rule that the absorbent vessels arise by closed extremities, and 
 not by open mouths. See p. 370.] 
 
 t [These networks are arranged in layers, the most superficial of which is formed by the finest vessels, and 
 has the smallest meshes.] 
 
m4 
 
 ANGEIOLOGY. 
 
 Course of the Lymphatics. 
 
 From the networks above described, the lymphatics themselves arise, and, in aD the 
 organs, are divided into a deep and a superficial set. The former set accompany the deep 
 vessels of the organ, while the others follow the superficial veins in such parts of the 
 body as are provided with them. In those organs which are covered with a serous coat, 
 they appear to be contained within the substance of that membrane. The lymphatics 
 run parallel with each other, and communicate pretty frequently by bifurcating, and then 
 joining the neighbouring vessels ; but they do not converge towards each other, nor do 
 they, like the veins, unite successively into a smaller and smaller number of larger and 
 larger branches ; thus, their increase in size is not progressive ; and it might even be 
 said that, throughout their whole course, they undergo no decided increase nor dimi- 
 nution. 
 
 Their direction is slightly tortuous. (In^^. 224 are shown short portions of lymphat- 
 ics of different sizes.) 
 
 Anastomoses. — ^We do not find in the lymphatics those numerous and important anas- 
 tomoses which form such characteristic points in the history of the arteries and veins. 
 These vessels present only one kind of anastomosis, which is accomplished in the fol- 
 lowing manner : A Ijonphatic, after a certain course, divides into two equal branches, 
 which diverge at a very acute angle ; these two branches anastomose with two other 
 lymphatics, each of which communicates either by bifurcation or directly with the neigh- 
 bouring lymphatic vessel. This explains how, by injecting a single lymphatic, a certain 
 group of these vessels may be filled. Not unfrequently, a lymphatic divides into two 
 branches, which, after a certain distance, again unite. 
 
 During their course, the lymphatic vessels meet certain small giandulifm-m ladies, the 
 conglobate glands of the ancients, but which are also called lymphatic ganglia, on account 
 of the analogy pointed out by Soemmerring between them and the ganglia of nerves ; the 
 lymphatic glands form centres, to which a number of lymphatic vessels proceed, and are 
 lost in them for a time, but from which they afterward emerge. 
 
 The name of afferent lymphatics (vasa afferentia, a a a, fig. 225) is applied to those 
 which enter a gland, and those which emerge from it are called efferent lymphatics (vasa 
 efferentia, b h). 
 
 Do all the lymphatics necessarily traverse one or more of these glands t Mascagni 
 has successfully maintained the affirmative in opposition to Hewson and others, who as- 
 sert that they have seen lymphatics entering directly into the thoracic duct. Mascagni 
 states that he invariably found that these vessels passed through one or more glands. 
 As to the argument derived from the absence of dropsy in oases of obstruction in the 
 lymphatic glands, Mascagni explains this by the frequent anastomoses of the lymphatic 
 vessels, the result of which is, that they communicate with several series of glands, 
 some of which are situated at very great distances. 
 
 The most numerous anastomoses of the lymphatics take place within the lymphatic 
 glands ; thus, if we inject the afferent vessels of a lymphatic gland, the mercury escapes 
 by its efferent vessels. In injecting a gland, it frequently happens that the mercury 
 passes not only into the efferent, but also into some of the afferent vessels. 
 
 Size of the Lymphatics. — The lymphatics are generally so small as to escape the no- 
 tice of the observer ; but they may become enlarged to a remarkable degree. Thus, I 
 have seen the lymphatics of the groin and of the uterus as large as the thumb. 
 
 An attempt has been made to draw some comparison between the toted capacities of 
 the lymphatic, venous, and arterial systems ; but all that has been said respecting this 
 is founded upon no positive data. I would, moreover, observe, that in all probability we 
 are acquainted with but a portion of the lymphatic system. 
 
 Termination of the Lymphatics. 
 
 According to the most generally received opinion, all the lymphatics terminate in two 
 trunks, the thoracic duct and the great right lymphatic duct; the latter vessel receives the 
 lymph from the right upper extremity, and from the right half of the head, neck, and tho- 
 rax ; the lymphatic vessels of all the other parts of the body end in the thoracic duct ; 
 the lymphatic vessels enter successively into these two trunks, as the plumes of a feath- 
 er are attached to its shaft. The two trunks themselves end as follows ; the thoracic 
 duct enters the left sub-clavian vein, at the junction of that vein with the internal jugu- 
 lar ; the great right lymphatic duct terminates in the right sub-clavian vein ; hence it is 
 that the lymphatic system may be regarded as an appendage of the venous system. 
 
 Are the thoracic and the great right lymphatic ducts, notwithstanding their small size, 
 the only terminations of the lymphatic system] With this question may be connected 
 another : Are the lymphatics the exclusive agents of absorption, or do they share this 
 function with the veins 1 
 
 Mascagni appeared to have established, beyond dispute, that absorption was performed 
 by the lymphatics to the exclusion of the veins ; when Magendie* and Delille in France, 
 
 * It is established, says M. Magendie, that the lacteals absorb the chyle, and that the intestinal veins ab- 
 
TERMINATION OF THE LYMPHATICS. 615 
 
 Tiedemann and Gmelin in Germany, and Flandrin and Emmert in England, relying upon 
 some ingenious experiments, again attributed a power of absorption to the veins, and 
 hence led other anatomists to undertake still farther researches. 
 
 The inquiry was soon entered upon by M. Fohmann in 1820 and 1821, by M. Lauth in 
 1824, and by M. Lippi in 1825, all of whom again referred the phenomena of absorption 
 exclusively to the lymphatics, and supported that opinion both by arguments and facts. 
 
 MM. Fohmann and Lauth admit two other modes of termination of the lymphatic sys- 
 tem in the veins besides the one already indicated : first, a direct termination of the 
 lymphatic radicles in the radicles of the veins, which is supposed to occur in the sub- 
 stance of organs ; and, secondly, a communication between the lymphatics and veins 
 within the lymphatic glands. This opinion, which seems reconcilable with the fact that 
 the area of the thoracic and right Ijonphatic ducts is very small as compared with that 
 of all the IjTnphatic vessels, appears, k priori, to be exceedingly probable. 
 
 But an anatomical fact must be shown anatomically before it can be admitted. Now 
 there is no proof of the communication of the lymphatic and venous radicles. M. Foh- 
 mann relies upon certain more or less ingenious inductions, but not upon direct ana- 
 tomical facts. I am, therefore, still compelled to doubt the existence of these commu- 
 nications, and to class them with the vasa serosa, or serous veins of Haller. 
 
 Again, a communication between the lymphatics and the veins in the substance of the 
 lymphatic glands had been conjectured by many anatomists ; the elder Meckel had seen 
 mercury, when thrown into the lumbar lymphatics, pass into the abdominal veins ; but 
 this fact was attributed to rupture in the interior of the glands. — {Hewson, Cruickskank.) 
 This apparent communication had also frequently been observed by Mascagni, and was 
 attributed by him to rupture. 
 
 M. Fohmann urges in reply, that this communication takes place under too slight a 
 pressure to be referred to rupture, that actual extravasations may be easily recognised, 
 and that the mercury is then infiltrated into the cellular tissue with much greater facility 
 than it can enter the veins. " Why," he asks, " supposing the existence of rupture, 
 does the mercury never pass from the lymphatics into the arteries 1" He also adduces 
 in support of his opinion a considerable number of facts, which show that injections 
 thrown into the lymphatic glands sometimes escape by the lymphatics alone, sometimes 
 by the veins alone, and sometimes by both the lymphatics and the veins. He states 
 that, having emptied the veins passing out from a mesenteric gland in a horse which had 
 been killed while digestion was going on, and having replaced the intestines in the ab- 
 domen, he found some streaks of chyle in the veins. Lastly, he has seen, in birds, the 
 renal lymphatic vessels, which represent the l)Tmphatic glands in those animals, opening 
 directly into the renal and sacral veins. M. Lauth has repeated these experiments, and 
 obtained the same results. But, however imposing the authority of the authors just ci- 
 ted may be, I must confess that I am far from being convinced, and that the facts stated 
 by them do not appear to me to be conclusive. I have made a great number of injec- 
 tions of lymphatics, and in by far the greater number of cases the mercury passed from 
 the afferent into the efferent lymphatic vessels, and not at all into the veins. In some 
 cases, it passed from the glands into the veins ; but it appeared to me that the glands 
 had then undergone a change in their texture, more particularly a red softening. 
 
 It does not seem to me, then, to be shown that there is any direct conununication be- 
 tween the lymphatics and the veins within the substance of the lymphatic glands. 
 
 Lippi (of Florence) denies the communication of the lymphatics with the veins within 
 the lymphatic glands ; but believes that, besides the terminations of the lymphatics in 
 the venous system through the thoracic duct and the great right lymphatic trunk, there 
 are a great number of direct communications between the lymphatics and the vena por- 
 tae, the internal pudic and the renal veins, and the vena cava ascendens and vena azygos. 
 
 Several anatomists, indeed, had already met with lymphatic vessels opening directly 
 into the venous system ; among whom were Walceus, Wepfer, Abraham Kaw, Heben- 
 streit, the elder Meckel, Galdani, and Vrolyk ; but the isolated facts recorded by them 
 were regarded by Haller, Mascagni, and Soemmering as anomalies, or as the results of 
 rupture. 
 
 The memoir published by Lippi excited new investigations on all sides. I was the 
 more inclined to subscribe to the opinions of that observer, because, in 1825, I had most 
 distinctly seen a large lymphatic trunk opening directly into the external iliac vein ; be- 
 cause it appeared to me rational to admit that the communications between the lymphatic 
 and venous systems would not be restricted to the internal jugular and sub-clavian veins ; 
 because the communications supposed to exist by Fohmann and Lauth had not been de- 
 monstrated ; because ligature of the thoracic duct does not prove fatal to all anunals 
 subjected to that experiment, even when the duct is single ; and, lastly, because the 
 thoracic duct has been found obliterated in many individuals. There seemed, besides, a 
 difliculty in admitting that the thoracic and right lymphatic ducts formed the termination 
 
 Borb other substances. It is shown that the veins are the absorbing- agents in other parts of the body, but tt 
 is not shown that the lymphatics absorb. Some authors have stated that the veins absorb only when the lym- 
 phatic; system is diseased. 
 
616 ANOEIOIiOGT. 
 
 of the whole of the lymphatic vessels. It appeared, moreover, at variance with the gen- 
 eral laws of the animal economy to suppose that two sets of organs should be devoted to 
 the same functions ; fbr, if the veins absorb, the lymphatic system would seem to have 
 no special use. 
 
 Nevertheless, truth compels me to state that, after the most minute and frequent re- 
 searches which I have been able to make, I have not obtained a single result confirma- 
 tory of the statements of M. Lippi ; and that, with his plates before me, I have searched 
 for the communications in all the points which he has indicated, and have never found 
 any. I am, therefore, obliged to conclude, with MM. Rossi, Fohmann, and others, that 
 the vessels which M. Lippi has described as lymphatics opening into different parts of 
 the venous system are nothing more than veins. 
 
 Structure of the Lymphatics. 
 
 The lymphatics, as well as the veins, have two coats. This structure can be readUy 
 shown in the thoracic duct of the human subject, and still better in that of the horse : the 
 existence of these two coats may also be shown by a method suggested by Cruickshank, 
 which consists in turning the thoracic duct inside out, and forcibly introducing a tube 
 into it ; the lining membrane, which is then on the outside, being less extensible than 
 the external coat, becomes lacerated. 
 
 The external coat is considered to be fibrous by some, and muscular by others. Shel- 
 don says that he has distinctly seen muscular fibres arranged circularly around the tho- 
 racic duct of the horse. It appears to me that this external coat resembles the dartoid 
 tissue, like the outer coat of the veins. It is not uninteresting to remark, that the outer 
 surface of the lymphatics is often covered by a thin layer of fat, which has deceived sev- 
 eral anatomists. 
 
 The internal coat of the lymphatic vessels appears to be of a serous nature, like that of 
 the veins. Some arterial and venous twigs ramify in their parietes ; but no nerves have 
 yet been traced into them. Minute lymphatics probably arise from the coats of the larger 
 ones. Mascagni believes that their lining membrane is entirely lymphatic. 
 
 Notwithstanding their excessive tenuity, the lymphatics are tolerably strong ; less so, 
 however, than is generally stated, for they are often lacerated by the weight of a small 
 column of mercury. They do not appear to me to be stronger than the veins. They are 
 much less extensible. When the thoracic duct, or any other lymphatic vessel, is punc- 
 tured, it immediately collapses, and forces out its fluid contents sometimes in a jet. Some 
 admit the existence of muscular contractility in them. The vemiicular motion caused 
 by contraction of their external coat is sufficient to explain the above-named fact.* 
 The lymphatics are much more abundantly supplied with valves than the veins. The 
 Fig. 224. valves {a a, Jig. 224) are parabolic, and are arranged in pairs ; they 
 
 have an adherent border turned towards the commencement, and a free 
 border towards the termination of the vessel ; they are generally sit- 
 uated at very short intervals apart, as is shown by the knotted ap- 
 pearance of the vessels (see fig. 224), and occasionally they present 
 a circular or annular arrangement, from which they have been re- 
 garded as true sphincters. 
 
 In general, these valves are strong enough to prevent the retrograde 
 course of the lymph, and, consequently, of injections also. Never- 
 theless, Hunter inflated all the lacteals from the thoracic duct ; Hal- 
 ler filled all the lymphatics of the lung from the upper part of the same 
 canal, and Marchettis says that he has injected the whole of the lym- 
 phatics from the reservoir of Pecquet. The valves are extremely 
 numerous in the lymphatics ; they have sometimes appeared to me 
 to be wanting in the thoracic duct. Like those of the veins, the 
 valves of the lymphatic vessels appear to be formed by a fold of the 
 internal membrane. 
 
 The Lymphatic Glands. 
 
 Sylvius was the first to distinguish the lymphatic glands under the term conglobate 
 glands, from the glands properly so called, which he named conglomerate. Chaussier 
 called these little bodies lymphatic ganglia, following Soemmering, who first pointed out 
 the analogy between them and the venous ganglia. 
 
 The lymphatic glands are situated along the course of the lymphatic vessels, in refer- 
 ence to which they may be regarded as centres in which a certain number of the ves- 
 sels open ; those of the extremities are chiefly found at the upper part of the limbs on 
 the aspect of flexion ; those of the thorax, the abdomen, the head, and the neck are pla- 
 ced along the vertebral column and the great vessels ; they are found also in tlie sub- 
 stance of the mesentery, in the mediastina, at the roots of the lungs, &c. 
 
 * [The lacteal vessels have been seen to underijo a slow contractility on exposure to air. or to the action of 
 any other stimulus ; but there is no evidence of the muscularity of any part of the lymphatic system of mam 
 malia. In certain reptilia and amphibia there are pulsating muscular sacs connected with the lymphatic syi 
 tern, v?hich are called lymphatic hearts.'^ 
 
PREPARATION OF THE LYMPHATIC VESSELS AND GLANDS. 617 
 
 Their size varies from that of a millet seed to that of a large filbert. The smallest are 
 situated in the epiploon, the largest at the roots of the lungs. They are often greatly 
 enlarged by disease. They are generally of a reddish-gray colour, excepting at the root 
 of the lungs, when they are black. Their form is irregularly spheroidal ; and they have 
 been distinctly shown by Malpighi to have a cellular structure.* If we examine with a 
 lens a lymphatic gland distended with fluid, we observe that it contains cells ; the same 
 fact is clearly demonstrated by injecting it with mercury, which shows, moreover, that 
 the cells communicate freely with each other. It is, nevertheless, doubtful whether all 
 the cells communicate. The researches which I have made upon this subject appear 
 to show that each lymphatic vessel is connected with a distinct portion of the lymphatic 
 gland ; and diseases of the glands establish the same fact, by attacking one part only of 
 a gland, the rest continuing unaffected. 
 
 Several l)rmphat?ic vessels enter each gland, and several emerge from it. Each affer- 
 ent vessel (a a a, fig. 225), as it reaches the circumference of the pig. 225. 
 gland, divides into a considerable number of branches, which diverge 
 and run for a short distance upon the surface of the gland, and then 
 dip into its substance.! The efferent lymphatics (i b) commence in 
 precisely the same manner as the afferent vessels terminate. 
 
 The study of these vessels in the larger animals appears calcula- 
 ted to clear up all doubts as to the structure of the lymphatic glands. 
 Abernethy having injected the mesenteric arteries and veins of a 
 whale, saw the fluid run into pouches about the size of an orange ; 
 he then injected mercury into the lacteals, and found that it flowed 
 into the same cavities ; he therefore concluded that the arteries, 
 veins, and lacteals all opened into the same cavities. This fact ap- 
 pears to confirm the observations quoted by MM. Fohmann and Lauth, 
 relative to the communications of the lymphatics with the veins 
 within the substance of the glands ; but the objections already urged 
 against those observations will apply to this one also. 
 
 The lymphatic glands are enclosed in a fibrous membrane ; I have 
 in vain attempted to find the fleshy coat described by Malpighi, and which he imagined 
 sent prolongations into the substance of these glands. 
 
 The lymphatic glands are supplied with very large arteries for their size, and they 
 give off still larger veins : a proper tissue {d) appears to enter into their composition. 
 
 The lymphatic glands may be said to consist essentially of an inextricable interlace- 
 ment of lymphatic vessels, their structure having some analogy to that of the corpus 
 cavernosum penis, and to that of the spleen. This opinion is confirmed by reference to 
 the anatomy of birds, in which lymphatic glands exist only in the neck, their place being 
 supplied by plexuses in all other parts. 
 
 Preparation of the Lymphatic Vessels and Glands. 
 
 I have already said, that in order to inject the network of lymphatics, the pipe should 
 be very superficially introduced into the free cutaneous, serous, or mucous surfaces. 
 When the injection is successful, the mercury passes from this network into the vessels 
 which emerge from it, reaches as far as the l3anphatic glands, and even penetrates through 
 several series of them. 
 
 The great number and peculiar arrangement of the valves prevents the injection of the 
 lymphatics from the centre towards the extremities ; I have attempted to do this several 
 times, without success, by introducing the tube into the thoracic duct. 
 
 From the small caliber of the lymphatics, it is necessary to use a capillary tube for 
 these injections. Mercury, notwithstanding the inconvenience of its fluidity, and in- 
 capability of being made solid, is the most convenient material for the purpose ; the 
 weight of a column of mercury about fifteen or eighteen inches in height aflJbrds suffi- 
 cient power for the injection. Anel's syringe is well adapted for injecting the thoracic 
 duct, which may be filled with a solution of isinglass, or, still better, with milk, which be- 
 comes coagulated by the alcohol. The best apparatus for injecting the lymphatics is a 
 glass cylinder, to the lower end of which is adapted a flexible tube, which is terminated 
 by a metal pipe, provided with a stopcock, and supporting a capillary tube of glass, which 
 is better than one made of steel or platinum, like those generally used in Germany. A 
 ring is attached to the upper end of the glass tube, by means of which the apparatus may 
 be suspended : this greatly facilitates the employment of the apparatus. 
 
 In order to inject the lymphatics, one of these vessels should be exposed at a greater 
 or less distance from the centre ; for example, in the lower extremity, upon either the 
 internal or external malleolus, or, what is still better, over the metatarso-phalangal artic- 
 ulations, in the way practised by Mascagni ; the vessel must then be punctured, and 
 the tube introduced into its interior ; the stopcock is then opened, and the mercury run? 
 
 * See note, infra. 
 
 t [Within the gland the lymphatics form a dense network (c) ; when the vessels of which this network ia 
 composed are distended, they give the cellular appearance to a section of the g-land noticed by Malpighi. 
 Cruickshank, <&c.] 
 
 41 
 
'IBI'8 ANGEIOLOGY. 
 
 as far as the gland into which the vessels opens, and at the same time enters all the 
 vessels which anastomose either directly or indirectly with the one into which the tube 
 IS introduced. The vasa efferentia are also soon injected, and if the experiment be con- 
 tinued long enough, the mercury will, in all probability, reach the thoracic duct if no 
 rupture should occur. The internal jugular, sub-clavian, and brachio-cephalic veins of 
 both sides of the body may be previously injected, in order to prevent the mercury enter- 
 ing these vessels by the thoracic duct and its supplemental canals. 
 
 We may also have recourse to the following method, on account of its greater facility . 
 Puncture a lymphatic gland with a capillary tube ; all the efferent vessels which com- 
 municate with the cells thus punctured, and all the other portions of the lymphatic sys- 
 tem which communicate with those vessels, will thus be injected. But this method is 
 manifestly defective. 
 
 With regard to the choice of subjects, it may be remarked that the lymphatics are 
 much more easily seen when the cellular tissue is moderately infiltrated than when there 
 is extreme emaciation. Fat subjects are the worst of all : adults are preferable to chil- 
 dren and old subjects. 
 
 In describing the lymphatics, I shall follow the same arrangement as Mascagni, with 
 some slight modifications. Thus, after having described the thoracic duct and the great 
 right lymphatic trunk, I shall notice in succession all the lymphatic vessels which enter 
 it, beginning with those of the lower extremities. I shall not describe the vessels and 
 glands separately, but I shall group the vessels around the glands, as around central 
 points towards which they all converge. 
 
 DESCRIPTION OF THE LYMPHATIC SYSTEM. 
 The Thoracic Duct — the Right Thoracic Duct. — The Lymphatic System of the Lower Ex- 
 tremity — of the Pelvic and, Lumbar Regions — of the Liver — of the Stomach, Spleen, and 
 Pancreas — of the Intestines — of the Thorax — of the Head — of the Cervical Regions — of the 
 Upper Extremity and Upper Part of the Trunk. 
 
 The Thohacic Duct. 
 
 Dissection. — The thoracic duct may be examined, when distended with chyle, in an 
 animal killed during the process of digestion. If it is to be injected in the human sub- 
 ject, turn the intestines to the left and the liver to the right ; seek for the reservoir of 
 Pecquet (receptaculum chyli) between the aorta and the right crus of the diaphragm ; fol- 
 low one of the lymphatic trunks leading from this reservoir to the lumbar glands, and 
 puncture it with the injecting tube. Care must be taken to tie the left sub-clavian vein 
 both on the inside and on the outside of the termination of the internal jugular vein ; or, 
 still better, first fill the sub-clavian and internal jugular veins with a solid injection. If 
 we wish to make a preparation to be preserved, it is much better to inject the thoracic 
 duct with isinglass size by an Anel's syringe than to use mercury. 
 
 The thoracic duct {s 1 1 u, fig. 223), so called from its situation, is the common trunk 
 of all the lymphatics of the human body, excepting those of the right side of the head, 
 neck, and thorax, and of the right upper extremity. 
 
 It commences opposite the second lumbar vertebra, by the junction of a variable num- 
 ber of branches : Meckel says there are three, but I have generally found five or six. 
 These vessels, which are usually of large size, pass out from the abdominal lymphatic 
 glands ; they all converge towards a dilatation or ampulla of a triangular shape, which 
 is called the reservoir or cistern of Pecquet (cisterna, receptaculum chyli, s, fig. 223), after 
 the anatomist who showed that the lacteals did not pass to the liver, as was generally be- 
 lieved, in accordance with the opinion of Aselli, but that they entered the thoracic duct. 
 
 This ampulla, which is often nothing more than the point at which the lymphatic ves- 
 sels meet, and presents no dilatation, is situated to the right of and behind the aorta, 
 immediately below the aortic opening in the diaphragm, and by the side of the right eras 
 of that muscle. 
 
 Having commenced thus, the thoracic duct passes verticaUy upward, enters the tho- 
 rax through the aortic opening in the diaphragm, and becomes situated in the posterior 
 mediastinum {t t), in front of the vertebral coliunn, a little to the right of the median 
 Jine, and has the vena azygos (a a') on its right side, and the aorta on its left. Having 
 reached the front of the fourth dorsal vertebra, it inclines towards the left, still continu- 
 ing to ascend, passes behind the aorta, gains the left side of the oesophagus, runs along 
 oehind and on the inner side of the left sub-clavian artery, and escapes through the su- 
 perior opening of the thorax ; having arrived behind the left internal jugular vein, and 
 in front of the seventh cervical vertebra, it immediately bends forward, so as to form an 
 arch (m) like that of the aorta, and finally opens into the angle formed by the junction of 
 the left internal jugular and sub-clavian veins, or sometimes into the sub-clavian vein 
 externally to that angle. The direction of the thoracic duct is not straight, but flexu- 
 ous : its windings are sometimes very mmierous. 
 
 From the relations of the thoracic duct while within the posterior mediastinum, it fol- 
 
THE RIGHT THORACIC DUCT, ETC. ^'Wfe 
 
 lows that, in order to expose its lower portion, it must be sought for on the right side 
 of that cavity, and that we must look for its upper portion on the left side, and must di- 
 vide the left layer of the mediastinum in order to expose it. 
 
 The thoracic duct terminates in many different ways : thus, it not unfrequently opens 
 by several trunks into the left internal jugular and sub-clavian veins. A still more fre- 
 quent method of termination, and one which it is extremely important to know, is that 
 in which the duct, at its upper part, is divided into two branches, the left one of which 
 (m) is distributed in the usual manner, while the right (indicated by a smaller letter «) 
 opens into the right sub-clavian vein in connexion with the great lymphatic duct of the 
 right side. 
 
 The caliber of the thoracic duct is not at all proportioned to the number and size of 
 the lymphatics which terminate in it. Sometimes, in fact, lymphatics are found which, 
 when distended, are as large as a goose-quill. Still less is it proportioned to all the 
 lymphatics of the body, of which it is regarded as the common trunk. Its caliber is even 
 smaller than that acquired by some lymphatics under many circumstances ; for exam- 
 ple, by those of the uterus during pregnancy : this is a powerful argument in favour of 
 those who regard the thoracic duct as by no means corresponding to all the lymphatics 
 of the human body. 
 
 The thoracic duct is not of uniform caliber in its entire length. It commences by a 
 dilatation of two or three lines in diameter ; in the middle of the thorax it becomes con- 
 tracted to less than two lines in diameter, and it is again dilated a little at the arch 
 which it forms before its termination. 
 
 The thoracic duct not unfrequently divides, during its course, into several branches, 
 which form a sort of network ; it often subdivides into two branches of unequal size, 
 which unite again after a variable distance. 
 
 The thoracic duct receives, while in the thorax, a very large trunk, which is derived 
 from the liver, and perforates the diaphragm through a special opening. I have seen this 
 trunk cross and continue in front of the thoracic duct, being equal to it in size, and at 
 last enter it opposite the fifth dorsal vertebra. 
 
 The thoracic duct has been observed to end on the right side, and then the lymphat- 
 ics of the left side of the head, left upper extremity, left lung, and left side of the heart, 
 entered separately into the sub-clavian vein of the corresponding side. Meckel has cor- 
 rectly observed, that such a disposition is a first trace of the lateral transposition of the 
 viscera. 
 
 Valves. — Of all parts of the lymphatic system, the thoracic duct has the fewest and 
 the smallest valves. The most remarkable are those situated at its termination in the 
 sub-clavian vein ; their free borders are turned towards the vein, so that they oppose 
 any influx of the venous blood into the thoracic duct. The free borders of the other 
 valves, when they exist, are turned upward, their convex borders being directed down- 
 ward : the course of the fluid within the duct is, therefore, from below upward. 
 
 The Right Thoracic Duct. 
 
 The great right lymphaiic duct, or right thoracic duct, is a large vessel, the common 
 trunk of all the lymphatics derived from the right half of the head and neck, the right 
 upper extremity, the right lung, the right side of the heart, and often, also, of those from 
 the right half of the diaphragm and of the liver. This trunk (v, fig. 223), which is not 
 more than an inch long, resembles the curved portion of the thoracic duct ; it opens at 
 the angle formed by the junction of the right internal jugular and sub-clavian veins. 
 
 Sometimes this common trunk does not exist, and then the lymphatics, by the junc- 
 tion of which it is usually formed, enter the veins separately. Anastomoses always ex- 
 ist, moreover, between the left and right thoracic ducts. 
 
 The Lymphatic System of the Lower Extremity. 
 
 The Lymphatic Glands of the Lower Extremity. 
 
 Tlie lymphatic glands of the lower extremity are the anterior tibial gland, the popliteal 
 gland, and the inguinal glands. 
 
 The anterior tibial gland is situated at a variable height in front of the interosseous 
 ligament, generally at its upper part. Hewson has seen it below the middle : Meckel 
 has found two glands here ; but the existence even of one gland is not constant. 
 
 The popliteal glands are four in number ; one of them is situated immediately beneath 
 the fascia ; the other three are placed deeply at variable heights along the vessels of the 
 popliteal space : they are rather small. 
 
 The inguinal glands are the most numerous and important ; they are situated in the 
 fold of the groin, below Poupart's ligament, and are generally grouped around the en- 
 trance of the internal saphenous into the femoral vein, in a sort of depression formed 
 between the adductor longus and pectineus on the inside, and the psoas and iliacus on 
 the outside. They are not unfrequently continued along the internal saphenous vein as 
 low down as the middle of the thigh. They are divided into superficial and deep. The 
 latter are very variable in size and number, and are often wanting : they are sometimes 
 
620 ANGEIOLOGY. 
 
 continuous with the superficial, through the saphenous opening in the fascia lata. Thff 
 number of the superficial glands also varies much : it is nearly always inversely propor- 
 tioned to the size of the glands, which is also subject to great variety in diflferent indi- 
 viduals and at different ages. There can be no doubt that these differences in number 
 and in size depend, ceteris paribus, no less upon actual differences than upon the subdivis- 
 ion of one gland into several, or, rather, upon the union of a certain number of glands 
 into one. Sometimes we find a large circular gland situated around the termination of 
 the saphenous vein. The inguinal glands, moreover, are placed at different depths in 
 the substance of the fibrous layers which constitute the superficial fascia. Several of 
 these glands are frequently united to each other, not only by lymphatic vessels, but also 
 by prolongations of their proper substance. 
 
 The Lymphatic Vessels which enter the Lymphatic Glands of the Lower Ex- 
 tremity. 
 
 Preparation. — Introduce the pipe into some of the lymphatic vessels between the toes, 
 over the metatarso-phalangal articulations. Mascagni employed this method, which is 
 as easy as introducing the pipe into the vessels which run between the internal malleo- 
 lus and the skin. A still better method of injection, when it proves successful, is to fill 
 the lymphatic network in the skin by introducing the pipe into the dermis at any point 
 beneath the cuticle. But the limb requires to be warmed for this injection to succeed. 
 I have made a very beautiful preparation by injecting the cutaneous network of lymphat- 
 ics upon the sole of the foot in a new-born infant. The mercury ran as far as the glands 
 situated along the iliac vessels. 
 
 If the pipe be inserted into the skin upon the scrotum, or into the mucous membrane 
 covering the glans penis in the male, or into the skin of the labia majora in the female, 
 the mercury will reach the lymphatic glands of the groin. 
 
 The lymphatics which ramify in the gluteal region, and those situated in the sub-cu- 
 taneous cellular tissue of the abdominal parietes, may be injected in the same manner. 
 
 The deep lymphatics of the leg open into the anterior tibial gland and popliteal glands. 
 All the superficial lymphatics of the lower extremity, and also those of the gluteal re- 
 gion, perineum, external genital organs, and sub-umbilical portion of the parietes of the 
 abdomen, terminate in the inguinal glands. 
 
 Lymphatics of the Lower Extremities. — The lymphatics of the lower extremities, like 
 the veins, are divided into superficial and deep. 
 
 The deep-seated lymphatics are fewer in number and less accurately known than the 
 superficial ; they accompany the deep-seated bloodvessels. It is probable that every ar- 
 terial and venous branch has its corresponding lymphatics ; but those only which ac- 
 company the great vessels have been as yet discovered. They are divided into the pe- 
 roneal, the anterior and posterior tibial, and the femoral. 
 
 Of the anterior tibial lymphatics, two only have been demonstrated, although their num 
 ber must certainly be greater. One of these accompanies the plantar arch, the dorsal 
 artery and vein of the foot, and the anterior tibial vessels ; it communicates with the 
 posterior tibial and the peroneal lymphatics, opposite the upper part of the interosseous 
 ligament, and enters the anterior tibial gland, or more frequently perforates the interos- 
 seous ligament, and enters the popliteal glands. 
 
 The other anterior tibial lymphatic arises deeply from the outer side of the foot, and 
 joins the preceding. 
 
 The posterior tibial lymphatics, two or three in number, and likewise the peroneal lymphat- 
 ics, sometimes unite into a single trunk, and enter the popliteal glands. 
 
 The branches which emerge from the popliteal glands, five or six in number, traverse 
 the opening in the adductor muscle, ascend along the femoral vein, and open into the 
 deep inguinal glands. 
 
 The superficial lymphatics, which can be very easily shown to arise from a network in 
 the skin, run upward and inward, to reach the inner side of the leg, and then pass be- 
 hind the internal condyle of the femur : those which arise from the outer side of the foot 
 and leg, after ascending vertically in front of the muscles of the anterior region of the 
 leg, cross over the upper part of the tibia obliquely from without inward, so that all the 
 superficial lymphatics at last gain the inner and back part of the internal condyle of the 
 femur : from this point they incline forward like the sartorius, upon which they are pla- 
 ced, and then pass vertically upward, and are distributed to the different lymphatic glands 
 of the groin. 
 
 A certain number of lymphatic vessels which commence upon the outer border of 
 the foot (there are not more than two or three) pass over the external malleolus tc 
 reach the external saphenous vein, become sub-aponeurotic like that vein, and enter the 
 most superficial of the popliteal glands. These lymphatics, which accompany the exter- 
 nal saphenous vein, are regarded by some authors as forming part of the deep set o* 
 vessels. 
 
 Superficial Lymphatics of the External Genital Organs, Gluteal Region, Perineum, and 
 
THE PELVIC AND LUMBAR LYMPHATIC GLARDS. 621 
 
 Lower Part of the Abdomen. — The superficial lymphatic vessels from these parts also en- 
 ter the inguinal glands. 
 
 The superficial lymphatics of the external genital organs of the male are divided into those 
 of the scrotum and those of the penis. If the skin of the scrotum be injected, several 
 8ub-cutaneous branches will be seen to pass from the network beneath the epidermis 
 upward along the sides of the penis, and then, after describing a curve with the concav- 
 ity directed downward, to open into the inguinal glands, generally into those which are 
 nearest the middle line, but I have seen them pass to the glands surrounding the saphe- 
 nous opening. If we inject the skin of the penis, and more especially the membrane 
 covering the glans, the mercury penetrates into the dorsal lymphatics of the penis, and 
 reaches the innermost and highest of the inguinal glands. The injection from the skin 
 of the penis enters the superficial lymphatics ; the injection from the membrane cover- 
 ing the glans enters only those superficial lymphatics which accompany the dorsal blood- 
 vessels of the penis. 
 
 In the female, injections of the skin of the labia majora, and of the mucous membrane 
 of the labia majora, labia minora, and clitoris, yield similar results as the injection of 
 the scrotum and penis in the male. We know that diseases of the labia, nymphai, and 
 clitoris, like those of the prepuce, penis, and scrotum, occasion enlargement of the in- 
 guinal lymphatic glands. 
 
 The lymphatics of the perineum unite with the preceding, and with the lymphatics of the 
 lower extremities. 
 
 The superficial lymphatics of the gluteal region turn horizontally round the glutaeus max- 
 imus and medius, and enter the external and middle lymphatic glands of the groin. This 
 is the reason why furunculi or other diseases of the skin upon the nates may give rise 
 to enlargement of the inguinal glands. 
 
 The superficial lumbar lymphatics, as well as those of the sub-umiilical portion of the 
 abdominal parietes, have a descending course : those of the loins run forward and down- 
 ward, those of the abdomen vertically downward ; they both terminate in the outermost 
 and highest of the inguinal glands ; and hence diseases of the skin covering the lumbar 
 and sub-umbilical regions may occasion swelling of the inguinal glands. 
 
 The lymphatic vessels which accompany the epigastric and circumflex iliac veins also 
 enter the glands of the groin. 
 
 The Lymphatic System of the Pelvic and Lumbar Regions. 
 The Pelvic and Lumbar Lymphatic Glands. 
 
 The lymphatic glands of the pelvis are divided into the external iliac, the internal iliac, 
 and the sacral. 
 
 The external iliac lymphatic glands, irregular in number, are situated along the artery 
 of that name. Three of them require to be particularly noticed ; they are situated im- 
 mediately behind the femoral arch, one of them on the outer side, another in front, and 
 the third on the inner side of the external iliac vessels. It is important, in reference to 
 the ligature of the external iliac artery, to know that these lymphatic glands are subject 
 to enlargement. 
 
 The internal iliac lymphatic glands occupy the space between the external and internal 
 iliac vessels. The bladder has proper lymphatic glands situated upon its posterior sur- 
 face, and near its summit. In the female, some of the pelvic lymphatic glands may be 
 regarded as belonging to the vagina and uterus. One tolerably large gland, which may 
 be said to be constant, occupies the internal orifice of the obturator canal, and I have 
 often found it inflamed or indurated in diseases of the uterus. 
 
 The sacral lymphatic glands occupy the sides of the anterior surface of the sacrum : 
 several of them are situated within the folds of the meso-rectum, and belong to the rec- 
 tum itself 
 
 The lumbar or aortic lymphatic glands are very numerous, and form a continuous chain 
 with the pelvic glands ; they occupy the angular interval between the conunon iliac ar- 
 teries, being placed along those arteries themselves, and also surround the aorta and the 
 ascending vena cava, but more particularly the aorta. It is important to note the rela- 
 tion of these lymphatic glands with the aorta, for that vessel is sometimes found much 
 compressed and narrowed from enlargements of these glands by tubercular or cancerous 
 deposite. 
 
 There is also a lymphatic gland in each intef-transverse space on both sides of the 
 lumbar region ; so that the lumbar lymphatic glands may be divided into the median and 
 the lateral. 
 
 The Lymphatic Vessels which enter the Pelvic and Lumbar Lymphatic Glands. 
 The different lymphatic vessels which proceed from the inguinal glands enter the pel- 
 vis behind the femoral arch, and near the femoral vein. The foramina through which 
 they pass are so numerous, that the fascia which is perforated by them is named the 
 cribriform fascia. Having arrived beneath the peritoneum, they are divided into two 
 
633' ANGEIOLOGY. 
 
 sets, one of which descends into the cavity of the pelvis, and tenninates in the several 
 internal iliac lymphatic glands ; while the other enters the external iliac glands, and 
 more particularly those situated behind the femoral arch. These external iliac glands, 
 moreover, are joined by the epigastric lymphatics, some of which enter the inguinal glands, 
 and by the ilio-lumbar lymphatics. 
 
 The lymphatic glands of the pelvis also receive the deep lymphatics of the nates, which 
 accompany the gluteal and sciatic arteries ; the lymphatics corresponding with the ob- 
 turator vessels ; the lymphatics of the bladder and lower end of the rectum, those of the 
 prostate and vesiculse seminales, and the deep lymphatics of the penis in the male, and 
 those of the vagina, clitoris, and neck of the uterus, in the female. The lymphatics of 
 the bladder, before entering the pelvic glands, traverse the glands proper to itself : the 
 greater number of the lymphatics of the bladder run beneath the peritoneum upon its 
 posterior surface. I have seen the vesical lymphatics filled with pus. Some other 
 lymphatics emerging from the internal iliac glands accompany the external and internal 
 iliac arteries and veins, ascend in front of the sacrum, pass through other lymphatic 
 glands, and arrive at the brim of the pelvis. At this point, the lymphatics of the right and 
 left sides unite together. These vessels pass through one or several series of lumbar 
 lymphatic glands, and at last open into the thoracic duct. This collection of lymphatic 
 vessels and glands forms the internal and external iliac lymphatic plexuses. The inter- 
 nal iliac lymphatic plexus is placed in the cavity of the pelvis, and surrounds the inter- 
 nal iliac vessels : the external iliac lymphatic plexus is situated along the vessels of that 
 name. 
 
 All the lymphatics of the lower extremities, after having passed through a greater oj 
 less number of glands, open at last into these lumbar glands, so that the vessels and 
 glands together may be said to form an uninterrupted chain. Thus, passing from plex- 
 us to plexus, and from gland to gland, the lymphatics of even the most distant parts ar- 
 rive, at length, at the thoracic duct. 
 
 The lateral lumbar lymphatic glands, viz., those which occupy the spaces between the 
 transverse processes of the lumbar vertebrae, receive the lumbar lymphatics, properly so 
 called, which correspond to the bloodvessels of that name. From these glands, commu- 
 nicating vessels pass to the aortic lumbar glands. The collection of lymphatic vessels 
 and glands occupying the lumbar region is called the lumbar lymphatic plexus. The 
 following lymphatic vessels also enter directly into the lumbar glands : the lymphatics 
 of the testicles in the male ; the lymphatics of the ovaries and Fallopion tubes, and also 
 of the body and upper part of the neck of the uterus, in the female ; and the lymphatics 
 of the kidneys in both sexes. 
 
 The Lymphatics of the Testicle. — It has been already stated that the lymphatics of the 
 covering of the testicle enter the superficial inguinal glands ; those which belong to the 
 gland itself are divided into the superficial and deep. The superficial lymphatics may be 
 injected with the greatest facility by puncturing the serous membrane covering the tu- 
 nica albuginea ; the tunica vaginalis will then appear as if covered with a coat of silver. 
 (See the beautiful plates of Panizza.) These superficial vessels have numerous commu- 
 nications with the deep-seated lymphatics, so that both sets are injected at the same 
 time. All the lymphatics from the epididymus and the body of the testicle, which are 
 very numerous and large, ascend with and assist in forming the spermatic cord, pass 
 through the inguinal canal, follow the course of the spermatic vessels, and enter the 
 lumbar lymphatic glands. 
 
 The Lymphatics of the Uterus. — Having, in diseases of the uterus incidental to the pu- 
 erperal state, frequently detected pus in the lymphatics of the uterus (vide Anat. Path., 
 liv. xiii., pi. 1, 2, 3), I have been able to trace the exact distribution of these vessels, and 
 would divide them into superficial and deep. The superficial lymphatics are situated im- 
 mediately under the peritoneum ; the deep lymphatics form several successive layers, 
 which occupy different planes within the substance of the uterus. The IjTnphatics near 
 the neck of this organ enter the pelvic and sacral lymphatic glands. A certain number 
 of the uterine lymphatics enter a lymphatic gland situated at the internal orifice of the 
 obturator canal. 
 
 All the uterine IjTnphatics, excepting those near the neck of that organ, pass towards 
 the sides and upper border of the uterus ; some run within the substance of the broad lig- 
 aments, and they all reach the upper or tubal angles of the viscus. They are joined by 
 the lymphatics of the ovaries, broad ligaments, and Fallopian tubes, and then ascend in 
 front of the corresponding ovarian artery and veins. Having arrived in front of the lower 
 part of the kidneys, they incline towards the middle line, and enter the glands which are 
 situated in front of the vena cava and aorta. Without having witnessed it, it is impos- 
 sible to form any idea of the enormous size which the uterine lymphatics may acquire 
 during pregnancy : several of these vessels, when filled with pus, become so dilated that 
 one would at first sight believe that an abscess had been formed. 
 
 The Lymphatics of the Kidneys and Supra-renal Capsules. — These are divided into super- 
 ficial and deep. The superficial lymphatics have never been injected directly ; but if a 
 fine injection be thrown into the renal arteries and veins, the injection, freed from col- 
 
THE LYMPHATICS Of THE LIVER. 623 
 
 ouring matter, passes into the lymphatics. This was the only way in which Mascagni 
 could inject the superficial lymphatics of the kidney, which he has represented in his 
 beautiful plates. 
 
 The deep lymphatics, which are very numerous, pass out of the fissure of the kidney, 
 and enter the glands in front of and behind the aorta and vena cava. 
 
 The lymphatics of the supra-renal capsules are remarkable for their size and number ; 
 they unite with those of the kidneys, and terminate in the same manner. 
 
 The Lymphatic System of the Liver. 
 Preparation. — Of all the lymphatic vessels, those of the liver are the most easily de- 
 monstrated. Before they are injected, they may be rendered more apparent, and even 
 be filled, by throwing water either into the hepatic arteries, the vena ports, the hepatic 
 veins, or the hepatic ducts. In order to inject them, it is sufficient to make a superfi- 
 cial puncture in any part of the peritoneum covering the liver ; but it is most convenient 
 to operate upon one of the lymphatic trunks which run upon the surface of that organ. 
 It is of importance that the tube should be introduced between the peritoneal covering 
 and the fibrous coat, without perforating the latter. It is sufficient to inject from a sin- 
 gle vessel in order to fill all the others. The mercury generally runs as far as the near- 
 est lymphatic gland, the resistance in which causes the fluid to flow back into the sur- 
 rounding branches, even as far as their most delicate ramifications, so that, in successful 
 injections, the whole surface of the liver has a silvery aspect ; the possibility of injecting 
 the lymphatics of the liver, from the trunks towards the branches, must lead us to sup- 
 pose that there are fewer valves in them than in the lymphatics of other pjirts of the body. 
 
 The Lymphatic Glands of the Liver. 
 These are situated along the hepatic vessels, behind the pylorus, and are continuous 
 with the cceliac lymphatic glands. I have seen them of a jet-black colour ; a liquid may 
 be expressed from them, resembling that contained in the bronchial lymphatic glands. 
 
 The Lymphatic Vessels of the Liver. 
 
 The lymphatics of the liver may be divided into the superficial and the deep. 
 
 The Superficial Lymphatics. — These are subdivided into those of the convex and those 
 of the concave surface. 
 
 The lymphatics of the convex surface of the liver consist of a certain number of trunks, 
 some of which belong to the right and the others to the left lobe. Some of them run 
 from behind forward, others from before backward, towards the posterior border of the 
 organ. 
 
 The first set, or those which run from behind forward, reach the suspensory ligament 
 of the liver, and unite into several trunks, some of which perforate the diaphragm, enter 
 the anterior mediastinum, behind the xiphoid cartilage, and tenninate in the mediastinal 
 lymphatic glands ; while others are reflected over the anterior margin of the liver, to 
 gain the longitudinal fissure, along which they run as far as the gastro-hepatic omentum, 
 by which they are conducted to the lymphatic glands placed round the pylorus, to tbose 
 around the cardiac orifice of the stomach, and to those which lie along the lesser curva- 
 ture of that organ, and near the lobulus Spigelii. 
 
 The second set of the lymphatics of the convex surface of the liver, or those which 
 run from before backward, having reached the posterior border of the liver, divide into 
 three distinct groups of vessels : those on the left enter the substance of the left triangu- 
 lar ligament of the liver ; those on the right pass into the right triangular ligament ; while 
 the remainder, which occupy the middle, enter the substance of the coronary ligament. 
 
 Those lymphatics of the second set that do not perforate the diaphragm enter the 
 lymphatic glands along the vena cava, and from thence reach the thoracic duct. Some 
 of them run along the lower border of the twelfth rib, and open into the glands situated 
 near its posterior extremity, and into another gland which rests upon the twelfth dorsal 
 vertebra. 
 
 Those lymphatics of the second set which do perforate the diaphragm pass through 
 its crura, and proceed, some to the intercostal lymphatic glands, or into those which lie 
 along the vena azygos and the aorta, and thence into the thoracic duct ; while others 
 enter that duct directly. I have seen a veiy large lymphatic trunk open directly into 
 the thoracic duct, opposite the fifth dorsal vertebra. Mascagni pointed out some lym- 
 phatic vessels which, after having perforated the fleshy fibres of the diaphragm, ran be- 
 tween the pleura and that muscle, re-entered the abdomen through the aortic opening in 
 the diaphragm, and then passed into the glands surrounding the aorta and vena cava, or 
 entered the thoracic duct at no great distance from the reservoir of Pecquet, without 
 passing through any lymphatic glands. 
 
 The lymphatics of the concave surface of the liver consist of several tninks, which are all 
 directed from before backward, and are divided into three sets : those which are situ- 
 ated to the right side of the gall-bladder ; those which surround it ; and those which are 
 situated to its left side. 
 
ANGEIOLOGY. 
 
 Those situated on the right of the gall-bladder partly enter the lumbar glands, and 
 partly terminate in the glands around the vena cava and aorta. 
 
 Those which surround the gall-bladder lorm a remarkable plexus, vphich accompanies 
 the hepatic vessels, and terminates in the lymphatic glands which lie along those ves- 
 sels, and in the glands situated in the substance of the gastro-hepatic omentum. Among 
 this set of lymphatics I would point out one considerable trunk, which runs in the cellu- 
 lar tissue connecting the gall-bladder to the liver. 
 
 The lymphatic trunks on the left of the gall-bladder end in the oesophageal lymphatic 
 glands, and in those which occupy the lesser curvature of the stomach. 
 
 The Deep-seated, Lymphatics of the Liver. — These vessels accompany the hepatic ducts 
 and the vena portae, and are contained with them in the capsule of Glisson ; they emerge 
 from the transverse fissure of the liver, penetrate the substance of the gastro-hepatic 
 omentum, and enter the lymphatic glands situated along the lesser curvature of the 
 stomach and behind the pancreas. 
 
 Those lymphatics of the liver which accompany the hepatic artery and duct and the 
 vena ports are extremely large, and are often filled with yellow lymph : they are some- 
 times found distended with gas in cases of commencing putrefaction. They were known 
 long before the lacteals ; indeed, they were the first lymphatic vessels that were dis- 
 covered. 
 
 The Lymphatic System of the Stomach, Spleen, and Pancreas. 
 The Lymphatic Glands of the Stomach,, Spleen,, and Pancreas. 
 
 Those of the stomach accompany the coronary vessels along the great and lesser cur- 
 vatures of the stomach ; some of them are situated within the gastro-splenic omentum, 
 and a great number surround the pyloric and cardiac orifices. 
 
 The lymphatic glands of the spleen occupy the hilus of that organ. 
 
 The pancreatic lymphatic glands are ranged along the splenic artery, and, consequently, 
 along the upper border of the pancreas ; several of them are grouped around the coeliac 
 axis. They receive a very great number of lymphatic vessels. 
 
 The Lymphatic Vessels of the Stomach, Spleen, and Pancreas. 
 
 The lymphatic vessels of the stomach are divided into the superficial and deep. 
 
 The sxiperficial lymphatics form a network beneath the peritoneum ; the deep lyni 
 phatics arise from an equally complex network situated in the mucous membrane. They 
 follow difl'erent directions : a great number of them pass to the great curvature, and enter 
 the glands situated there ; others proceed to the lesser curvature, and pass through the 
 glands in that situation. Several run towards the spleen, and enter the splenic lymphat- 
 ic glands ; and, lastly, others go to the lymphatic glands around the pylorus. 
 
 It has been stated that the lymphatics of the stomach have been seen filled with chyle : 
 this is at least doubtful. 
 
 The Lymphatics of the Spleen. — The superficial lymphatics of this organ cannot be seen 
 unless the splenic bloodvessels have been previously injected with size injection : the 
 size freed from the colouring matter will pass into them. I have seen tallow, thrown 
 into either the arteries or veins of the spleen, pass into the superficial lymphatics. It is 
 true that the injection was made forcibly, and kept up for some time. The deep lym- 
 phatics of the spleen are not known. 
 
 The proper lymphatics of the pancreas are little known. 
 
 The Lymphatic System of the Intestines. 
 The Lymphatic Glands of the Intestines. 
 
 The lymphatic glands of the small intestine, or the mesenteric glands, are extremely nu- 
 merous. Several anatomists, who have had the patience to count them, have arrived at 
 very different results, partly on account of individual varieties, and partly because sev- 
 eral, having chosen tuberculated subjects for the purpose, have mistaken the tubercles 
 for Ijnnphatic glands. 
 
 The mesenteric glands are situated between the folds of the mesentery, in the meshes of 
 the network formed by the arteries and veins. Those which are nearest to the intestine 
 are found in the intervals observed between the vessels of the mesentery close to the in- 
 testine. Those which are most distant from the intestine are situated near the adherent 
 border of the mesentery, along the trunk of the superior mesenteric artery. The largest 
 of these glands are found near the origin and termination of that artery. Thus we find, 
 below, a group of large lymphatic glands, the ileo-colic, opposite the termination of the il- 
 eum in the colon. Another cluster, named the duodenal, is situated above, in front of the du- 
 odenum : they are extremely large. We generally find one larger than the rest ; it is repre- 
 sented in the oldest works on anatomy, and has been sometimes mistaken for the pancreas. 
 
 The group of ileo-colic lymphatic glands is remarkable for frequently becoming inflamed 
 in follicular enteritis. 
 
 The lymphatic glands of the great intestine, or m^so-colic glands, much less numerous 
 than those of the mesentery, generally lie along the vascular arches formed by the colic 
 art(iries and veins : several of them are situated near the posterior border of the intes- 
 
THE LYMPHATICS OF THE INTESTINES, ETC. -fHI 
 
 tine ; and some are even found upon the intestine, accompanying those bloodvessels 
 which run for a short distance beneath the peritoneal coat, and then penetrate the mus- 
 cular coat. The meso-colic lymphatic glands are not nearly so numerous along the 
 transverse colon as along either the ascending or descending colon. Those situated in 
 the transverse meso-colon form an uninterrupted chain with the mesenteric glands. 
 
 The. Lymphcaic Vessels of the Intestines. 
 
 The Lymphatics of the Small Intestine.— These vessels are divided into two sets, the 
 lymphatics, properly so called, and the lacteals. 
 
 The lymphatics, properly so called, like those of the stomach and great intestine, arise 
 from two sets of networks ; one in the serous, the other in the mucous coats. The ves- 
 sels which pass out from these networks have a remarkable character, which was well 
 described by Mascagni ; instead of passing directly into the mesentery, they first proceed 
 for a short distance along the intestine, and then curve and enter the mesenteric glands. 
 
 The lacteals, or lacteal vessels of the small intestine, can be easily seen in an animal that 
 has been killed while the absorption of chyle is going on in the intestine ; and they have 
 occasionally been observed in the human subject, in cases of accidental death. They 
 then appear as white, nodulated, and slightly flexuous lines, which communicate occa- 
 sionally with each other, pass from one mesenteric gland to another, enter the lymphat- 
 ic glands situated in front of the aorta and vena cava, and terminate in the thoracic duct 
 by a variable number of trunks : the lymphatic plexuses of the left side pass behind the 
 aorta. 
 
 The lacteals commence, according to Lieberkuhn, upon the summit of each of the villi 
 «)f the small intestines, run down to its base, and then enter at right angles mto the sub- 
 mucous lacteal vessels, which invariably perforate the other coats of the intestine, on its 
 concave border. This arrangement was very evident in a case in which the lacteals were 
 filled with tuberculous matter. — {Anath. Pathol., liv. ii., pi. 2.)* 
 
 The Lymphatics of the Great Intestine. — We may, with Mascagni, divide these l)Tnphatics 
 into two sets, according to the glands in which they terminate, viz., those of the coecum 
 and of the ascending and transverse colon, which pass through the meso-colic lymphatic 
 glands, and then terminate in the mesenteric glands ; and those of the descending colon 
 and rectum, which enter the lumbar lymphatic glands together with the lymphatics of 
 the genital organs, and of the lower extremities. 
 
 The Lymphatic System of the Thorax. 
 
 The Lymphatic Glands of the Thorax. 
 
 The thoracic lymphatic glands are divided into those of the parietes of the thorax, 
 those of the mediastinum, and the bronchial or pulmonary glands. 
 
 The lymphatic glands of the parietes of the thorax are very small, and are thus arranged : 
 t>ie intercostal glands are situated on each side of the spine near the costo- vertebral ar- 
 ticulations ; some are placed between the two layers of the intercostal muscles : they 
 are very smaU, and irregular in number. The sub-sternal or mammary glands are found 
 at the anterior extremity of the intercostal spaces near the internal mammary vessels, 
 and applied along the borders of the sternum ; there is one for each intercostal space. 
 
 The mediastinal lymphatic glands are divided into those of the posterior mediastinum, which 
 are arranged along the cEsophagus and aorta, and form a continuation of the intercostal 
 glands : they have been known to become enlarged and press upon the oesophagus, so as 
 to cause dysphagia ; and into those of the anterior mediastinum, the principal of which lie 
 upon the diaphragm in front of the pericardium, and around the great vessels connected 
 with the base of the heart. 
 
 The bronchial or pulmonary glands were noticed by the oldest anatomists, and espe- 
 cially by Vesalius, whence the name of glandula Vcsdiance, by which they are still known : 
 they are remarkable for their situation, number, size, and colour. They are situated 
 along the bronchi and their first divisions. The largest are generally placed opposite 
 the bifurcation of the trachea. The smallest lie within the substance of the lungs, around 
 the first divisions of the bronchi ; some of them are seen in the inter-lobular fissures. 
 
 Their number is very considerable. 
 
 In disease, they may acquire such a size as to compress and narrow the bronchi, and 
 thus prevent the passage of the air through those tubes. 
 
 In infancy they do not differ in colour from the other lymphatic glands, but they are 
 black in the adult, and especially in the aged. They are also liable to become the seat 
 of depositions of phosphate of lime. 
 
 Senac considers them to be secreting glands quite distinct from the lymphatic glands. 
 Portal divided them into true glands and lymphatic glands ; but no one has been able to 
 demonstrate the excretory ducts, which, according to Portal, proceed from the lymphat- 
 ic glands upon the trachea. The communications between these and the trachea, ob- 
 served in some cases of disease, are altogether accidental. 
 
 * See also note, p. 368. 
 
 4K 
 
ANGEIOLOGY. 
 
 - The Lymphatic Vessels of the Thorax, 
 
 The lymphatic vessels of the thorax are divided into those of the parietes and those 
 of the organs contained in the thoracic cavity. 
 
 The Lymphatics of the Thoracic Parietes. — We shall here merely notice the deep-seat- 
 ed lymphatics. They are divided into the intercostal, the sub-sternal or internal mam- 
 mary, and the diaphragmatic. 
 
 The intercostal lymphatics accompany the arteries and veins of that name ; they re- 
 ceive the lymphatic vessels of the intercostal muscles and costal pleura, run along the 
 grooves of the ribs, pass through the intercostal lymphatic glands, reach the sides of the 
 vertebrae, unite with other lymphatics from the back of the thorax and from the spinal 
 canal, enter the lymphatic glands on the sides of the vertebral column, and are for the 
 most part directed downward to terminate in the thoracic duct. 
 
 The sub-sternal or internal mammary lymphatics arise from the supra-umbilical portion 
 of the anterior walls of the abdomen : they pass into the thorax, behind the ensiform 
 cartilage, and form two bundles, which run upon the sides of the sternum, unite with the 
 anterior intercostal and external mammary lymphatics, and enter the internal mammary 
 lymphatic glands. From the lowest of these glands other lymphatics proceed, and as- 
 cend in succession from one gland to another up to the inferior cervical lymphatic 
 glands ; on the left side they enter the thoracic duct, and on the right, the great lym- 
 phatic trunk. Sometimes, but rarely, the mjimmary lymphatics open directly into the 
 internal jugular and sub-clavian veins. 
 
 The lymphatics of the diaphragm for the most part unite with the intercostal and he- 
 patic lymphatics ; the others run forward between the pleura and the fleshy fibres of the 
 diaphragm ; some of them enter the inferior mediastinal glands, and the others, the in- 
 ternal mammary lymphatic glands. 
 
 The Lymphatics of the Thoracic Viscera. — The lymphatics of the lungs are divided into 
 superficial and deep : the superficial lymphatics may be injected in the same manner as 
 those of the liver ; they form an extremely close network beneath the pleura pulmonalis, 
 and frequently present a number of, as it were, varicose enlargements : these were no- 
 ticed and figured by Mascagni ; and the frequency of their occurrence led him to inquire 
 whether such was not the natural structure of lymphatics. Some of the vessels which 
 proceed from this network run in the inter-lobular fissures, and enter the lymphatic glands 
 situated at the bottom of these fissures ; while the others reach the internal surface of 
 the lung, and terminate in the bronchial glands. 
 
 These superficial lymphatics also communicate with the deep lym^phatics in the cel- 
 lular intervals between the lobules of the lung. 
 
 The deep lymphatics of the lung are very numerous : the manner in which they com- 
 mence in the lobules is not well known : they run in the inter-lobular cellular tissue, and 
 all proceed towards the root of the lung, in order to terminate in the glands situated 
 around the bronchi, and in several which lie along the oesophagus. It is doubtful wheth- 
 er a single pulmonary lymphatic vessel enters directly into another lymphatic gland 
 without first going through a bronchial gland. 
 
 Other lymphatics proceed from these bronchial glands ; some of which pass in front 
 of the trachea to enter the tracheal lymphatic glands, while the others proceed to the 
 lymphatic glands upon the oesophagus. On the left side both sets enter the thoracic 
 duct, at a short distance before its termination ; these are more numerous than those on 
 the right side, which enter the right lymphatic duct. Some of them terminate in the 
 thoracic duct, before it emerges from the thorax ; severeil of these vessels are sdso seen 
 to enter the internal jugular and sub-clavian veins. 
 
 I should observe that, in consequence of the above-mentioned anatomical fact, the 
 cervical lymphatic glands sometimes become enlarged in diseases of the lungs. 
 
 The Lymphatics of the Heart, Pericardium, and Thymus. — The lymphatics of the heart 
 are divided into superficial and deep ; the superficial vessels commence by a sub-serous 
 network, and, for the most part, run along the right border of that organ ; the deep lym- 
 phatics arise from the internal membrane of the heart, in which I have never been able 
 to inject a perfect network : they all accompany the coronary vessels, and all pass out 
 of the pericardium ; some of them unite with the lymphatics of the lung ; the others en- 
 ter the glands in front of the arch of the aorta and puhnonary artery, and from thence 
 pass to the thoracic duct. 
 
 The lymphatics of the pericardium and thymus enter the internal mammary, anterior 
 mediastinal, and bronchial lymphatic glands. 
 
 The Lymphatic System of the Head. 
 
 The Lymphatic Glands of the Head. 
 
 There are more lymphatic glands in the face than in the cranium. 
 
 All the lymphatic glands of the cranium are found upon its posterior region : some of 
 ■"them are situated behind the ear, along the attachments of the occipito-frontalis ; several 
 .are placed beneath the upper end of the sterno-mastoid ; they are very small, and often 
 
THt; I.YvIPHATICS OF THE HEAD, ETC. 627 
 
 escape notice in a hasty dissection : they become veiy distinct in diseases of the 
 scalp. 
 
 Are there any deep lymphatics of the cranium ? The pituitary body, the pineal gland, 
 and the white bodies known as the glandulae Pacchioni, have been regarded as belong- 
 ing to the lymphatic system. Some authors have even considered the tubercles, so 
 frequently found in the brains of infants, and which are evidently accidental formations, 
 to be of the same nature. Certain bodies found in the carotid canal, and which are 
 evidently enlargements of the ganglionic nerves, have also been described as lymphatic 
 glands ; but this opinion is now completely rejected. 
 
 Of the lymphatic glands of the face, the largest occupy the base of the lower jaw, and 
 are called the sub-maxillary l5Tnphatic glands : several of them are situated upon the 
 outer surface of the maxillary bone, along the facial vessels, in front of the masseter 
 muscle. 
 
 We find, also, in the face, the parotid lymphatic glands, some of which are superficial 
 and others deep, the latter being situated in the substance of the gland : we find some, 
 also, between this gland and the masseter : lastly, there are the zygomatic glands, situ- 
 ated imder the zygoma, and the buccinator lymphatic glands. 
 
 TJie Lymphatic Vessels of the Head. 
 
 These belong either to the cranium or to the face. 
 
 The Lymphatics of the Cranium. — The superficial or sub-cutaneous cranial lymphatics 
 are divided into two sets : the temporal lymphatics, which run along the superficial tem- 
 poral artery, and pass through the parotid lymphatic glands, from which vessels proceed 
 to the glands in the anterior region of the neck ; and the occipital lymphatics, which fol- 
 low the occipital artery, and terminate in the mastoid and the occipital lymphatic glands. 
 
 The deep lymphatics of the cranium, the lymphatics of the dura mater, or the meningeal 
 lymphatics, accompany the meningeal vessels, escape through the foramen spinale of the 
 sphenoid bone, and enter the jugular lymphatic glands. 
 
 Ruysch appears to have been the first who noticed lymphatics in the brain ; he has 
 named them vasa pseudo-lymphatica. Mascagni could only show the presence of the su- 
 perficial lymphatics of the brain by injecting coloured size into the carotid arteries. The 
 size freed from the colouring material passed into the lymphatics. 
 
 The lymphatics of the brain are but little known. M. Fohmann has described and 
 figured a lymphatic plexus situated between the arachnoid and pia mater, and precisely 
 resembling those found in other parts of the body. This network dips into the sulci, 
 and appears to be continued into the substance of the brain, where it is no longer possi- 
 ble to follow it. From this network some small lymphatic trunks proceed, and accom- 
 pany the arteries and veins as far as the foramina, in the base of the cranium, beyond 
 which M. Fohmann was never able to trace them ; so that he inquires whether these 
 vessels do not form an exception to the general rule from their want of connexion with 
 the absorbent system generally, and whether they do not enter directly with the veins 
 upon which they are- placed. On the other hand, Mascagni has figured some lymphatics 
 around the internal carotid, within the carotid canal, and also around the vertebral ar- 
 teries and internal jugular vein. The existence of these trunks leads us to suppose 
 that there must be cerebral lymphatics. 
 
 M. Fohmann has also found lymphatics in the choroid plexuses of the lateral ventri- 
 cles of the brain : these vessels were remarkably dilated, so as to present ampullae. 
 
 The Lymphatic Vessels of the Face. — These are divided into the superficial and deep. 
 
 The superficial lymphatics are much more numerous than those of the cranium. They 
 commence upon all parts of the face ; those from the frontal region accompany the 
 frontal vessels : the others accompany the adjacent bloodvessels ; several of them pass 
 through the buccinator glands, and they all finally enter the sub-maxillary lymphatic 
 glands. The lymphatics of the face are to be injected by introducing the pipe into the 
 plexus contained in the skin. 
 
 The deep lymphatics of the face accompany the bloodvessels. They are divided into 
 those of the temporal fossae, those of the zygomatic and pterygo-maxillary fossae, and 
 those of the nasal fossae. The lymphatics of the pharynx, velum palati, mouth, tongue, 
 and larynx, enter the deep parotid and the cervical lymphatic glands. The lymphatic 
 plexuses of the pituitary membrane, and of the lingual, buccal, and pharyngeal mucous 
 membranes, may be perfectly injected. Indeed, it is only in that way that we can 
 demonstrate the lymphatic vessels which emerge from these diflTerent parts 
 
 The Lymphatic System of the Cervical Regions. 
 The Cervical Lymphatic Glands. 
 The lymphatic glands of the neck are concentrated in the anterior region of the neck. 
 They are divided into the superficial and deep. 
 
 The superficial lymphatic glands of the neck are found principally along the external 
 jugular vein ; they are therefore situated between the platysma and the stemo-mastoid ; 
 and in the supra-clavicular triangle, that is to say, in the triangulfr interval between the 
 
6!^ ANGEIOLOGY. 
 
 «>- 
 clavicle, the sterno-mastoid, and the trapezius. We also find several very small supei- 
 ficial glands between the os hyoides and the thyroid cartilage, and upon the sides of the 
 larynx. 
 
 The deep lymphatic glands of the neck are very numerous, and form an uninterrupted 
 chain around the internal jugular vein and the carotid artery, from the mastoid process 
 to the superior opening of the thorax, in front of the vertebral column, and upon the 
 sides of the pharynx and oesophagus. 
 
 The tracheal lymphatic glands are also continuous with the deep cervical glands. 
 
 The cervical glands form a continued series with the facial and sub-maxillary lym- 
 phatic glands on the one hand, and with the lymphatic glands of the thorax and axilla 
 on the other. 
 
 The Cervical Lymphatic Vessels. 
 
 The cervical lymphatics consist of those which have passed through the sub-maxillary 
 and facial lymphatic glands, and which afterward traverse the chain of glands along the 
 jugular veins. They are joined by those of the pharynx, oesophagus, larynx, trachea, 
 and thyroid gland. They then proceed from one lymphatic gland to another, and from 
 one plexus to another, down to the lower part of the neck, where they are joined by 
 some lymphatics from the lung, which also pass through some of the cervical glands : 
 they terminate on the left side in the thoracic duct, and on the right side in the right 
 lymphatic duct. 
 
 The Lymphatic System of the Upper Extremity. 
 
 The Lymphatic Glands of the Upper Extremity and of the Upper Part of the 
 
 Trunk. 
 
 There are generally no lymphatic glands in the hand or forearm, but Meckel found 
 several very small ones along the ulnar and radial bloodvessels. There are two or three 
 which are sub-cutaneous in the front of the bend of the elbow, and one or two above the 
 internal condyle of the humerus, behind the basilic vein ; in the arm we also find a se 
 ries of small lymphatic glands, which are never numerous, along the inner side of the 
 humeral artery. 
 
 The axillary lymphatic glands are situated deeply in the axilla, and are very numerous , 
 some lie along the great vessels, others are scattered through the axilla : they are often 
 of a very large size. 
 
 The following may be regarded as appendages of the axillary glands : a small sub-cla- 
 vicular gland, situated deeply beneath the costo-coracoid membrane, opposite the trian- 
 gular interval between the pectoralis major and the deltoid, and two or three small glands 
 situated along the attachments of the pectoralis major, as far as the mammary gland. 
 
 Mascagni has figured a small lymphatic gland near the umbilicus. 
 
 The Lymphatic Vessels of the Upper Extremity and of the Upper Half of the 
 
 Trunk. 
 
 The Lymphatics of the Upper Extremity. — The superficial set of these vessels arise 
 from the skin of the hand, and run parallel to the fingers : they are, for the most part, sit- 
 uated upon the back of the hand ; they cross obliquely over the metacarpal bones, pass 
 over the carpus, and thus reach the forearm. 
 
 In the /orcarm they are distributed almost equally upon its anterior and posterior aspects. 
 
 The anterior lymphatics are collected upon the inner and outer sides of the forearm ; 
 having reached the elbow, some pass in front of the epitrochlea and its muscles ; others 
 in front of the epicondyle. In this place they are re-enforced by the lymphatics from 
 the posterior aspect of the forearm, which are also collected into an outer and innei' 
 group. Not unfrequently a certain number of the posterior lymphatics, which arise from 
 the outer side of the hand and forearm, after ascending almost vertically for some dis- 
 tance, pass obliquely, or cross transversely inward, above and below the olecranon, and 
 unite with the inner group. 
 
 In the arm some of the inner group of lymphatics pass to the lymphatic glands above 
 the epitrochlea ; the others run along the inner border of the biceps muscle and basilic 
 vein, and then pass backward and upward to reach the axillary glands. 
 
 The external lymphatics cross very obliquely over the anterior aspect of the arm, to 
 terminate, like the preceding, in the axillary glands. One of them has a remarkable 
 course ; it runs along the cephalic vein, gains the cellular interval between the pectoral- 
 is major and the deltoid, dips down over the upper edge of the pectorahs minor and be- 
 low the costo-coracoid membrane, and describes a curve so as to enter the sub-clavicu- 
 lar lymphatic ganglion. 
 
 The deep lymphatics of the upper extremity exactly follow the course of the bloodves- 
 sels ; they often communicate with the superficial lymphatics, and terminate in the ax- 
 illary glands. I have seen some of the deep lymphatics of the forearm communicate at 
 the bend of the elbow with the superficial lymphatics on the outer part of the back of the 
 arm, and enter the glands above the epitrochlea. 
 
THE SKIN. 010111^ 
 
 The Lymphatic Vessels of the Upper Half of the Trunk. — We have seen that all the lym- 
 phatics of the sub-umbilical portion of the trunk enter the inguinal glands ; and so all the 
 lymphatic vessels of the supra-umbilical portion terminate in the axilla. 
 
 The anterior and lateral lymphatics pass upward upon the pectoralis major and the ser- 
 ratus magnus, to gain the axilla. 
 
 The posterior lymphatics are divided into those of the neck and those of the back ; the 
 posterior cervical lymphatics descend upon the trapezius and the deltoid, and are reflected 
 over the posterior border of the leist-named muscle, in order to reach the cavity of the 
 axilla ; the posterior dorsal lymphatics run in different directions ; some horizontally, the 
 others from below upward, to be reflected into the axilla below the tendons of the la- 
 tissimus dorsi and teres major. 
 
 NEUROLOGY. 
 
 Neuroloot is that part of anatomy which treats of the apparatus of sensation and in- 
 nervation : this apparatus consists of the organs of the senses, of the cerebrospinal axis, 
 or central portion of the nervous system, and of the nerves, or peripheral portion of that 
 system. 
 
 THE ORGANS OF THE SENSES. 
 The Skin — its External Characters, Structure, and Appendages. — The Tongue considered as 
 the Organ of Taste. — The Organ of Smell — the Nose — the Pituitary Membrane. — The Or- 
 gan of Sight — the Eyebrows — the Eyelids — the Muscles of the Orbit — the Lachrymal Ap- 
 paratus — the Globe of the Eye, its Membranes and Humours — the Vessels and Nerves of the 
 Eye. — The Organ of Hearing — the External Ear — the Middle Ear or Tympanum — the 
 Internal Ear or Labyrinth — the Nerves and Vessels of the Ear. 
 
 The organs of the senses are certain parts of our bodies which are intended, by means 
 <n the sensibility they possess, to establish relations between us and external objects. 
 The organs of the senses, to use a strong figurative expression, are, as i« were, the 
 bridges which connect the individual with the world around him. — (^Meckel's Anatomy, by 
 Jourdan, p. 471.) 
 
 The organs of the senses, being placed between the brain and surrounding objects, 
 have the following characters in common : they occupy the surface of the body ; they 
 communicate with the brain by means of nerves of greater or less size ; and, lastly, each 
 of them has a peculiar structure in harmony with that particular quality of matter, the 
 perception of which it is intended to convey to us. 
 
 Anatomists generally admit five organs of sense, which we shall name, and then de- 
 scribe in the following order : the skin, or the organ of tact and touch, the organ of taste 
 the organ of smell, the organ of sight, and the organ of hearing. 
 
 The Skin. 
 General Remarks on the Skin. 
 The skin, the proper organ of tact and of touch, is a membrane which serves as a cov- 
 ering or integument to the body, and is so accurately moulded upon it as to preserve the 
 form, and yet conceal the inequalities, of its entire surface. It may be regarded as form- 
 ing an external surface or limit, endowed at the same time with sensibility and a poicer 
 of resistance ; enabling us by the one to perceive such qualities of bodies as are distin- 
 guishable by the touch, and by the other preserving us, to a certain extent from their ac- 
 tion. It forms, moreover, an exhalant surface, or sudorific organ, by which the system 
 is freed from noxious substances, and also an inhalant surface, by which fluids may be 
 absorbed.* 
 
 External Characters. 
 
 Examined in reference to its external characters, the skin presents an external or free 
 surface, and an internal or adherent surface. 
 
 The Free Surface. — Upon the/r«e surface of the skin the following objects require at- 
 tention : its folds, or wrinkles, and its furrows ; a peculiar colour, which is subject to 
 
 * Some ancient authors, Marcus Aurelius Severinus among others, adhering closely to the order of super- 
 imposition, which is sometimes called the anatomical order, commenced the description of the human body 
 with the skin ; and the same part, though for a very different reason, is described first by M. de Blainville, in 
 his Anatomic Comparie : that celebrated naturalist, carrying out analogical induction to its utmost limit», 
 makes the skin the fundamental organ of the body, connecting with it all the organs of the senses, which he 
 regards as analogous to hairs, and names phanerac (a word constructed by M. Blainville in opposition to the 
 term crypto:, hidden, and derived from ipapcfiog, evident, manifest, apparent). He considers that the appa- 
 ratus of locomotion is a development of the elastic element of the skin, which becomes endowed with contractili- 
 ty ; the digestive and respiratory organs he regards as modifications of the absorbent apparatus of tlie skin ; 
 and the organs of secretion and generation as developments of its e.xhalant structure. The circulatory appa- 
 ratus alone is not derived by him immediately from the external integuments ; yet he almost believes that it 
 is an extension or prolongation of the meshes of the cutaneous cellular tissue 
 
'6S0 NEUROLOGY. 
 
 variety in different races of men, and in different individuals ; certain horny growths, as 
 the nails and hairs, which are appendages of the skin ; and, lastly, numerous orifices for 
 the escape of the cutaneous secretions, some of them being the orifices of the sebaceous 
 foUicles, others of the sudorific glands, while others, again, are the foramina, or depres- 
 sions through which the hairs protrude. The horny growths of the skin will be noticed 
 presently ; and its colour and orifices, or pores, will be examined under the head of its 
 structure. 
 
 We shall here make a few remarks upon the different folds or wrinkles found in the 
 surface of the skin : they are of several kinds. 
 
 Some of them may be termed folds of locomotion ; they are permanent, and are inhe- 
 rent, as it were, in the skin itself, and have distinct relations to the various movements 
 of the body. They are of two kinds : the larger folds are observed around the joints, both 
 on the aspect of flexion, and that of extension ; for example, over the knuckles and in 
 the palms of the hands ; the small folds are found over the whole surface of the skin, 
 which is divided by them into irregular lozenge-shaped intervals ; it is to these folds that 
 the skin owes its extensibility. 
 
 Other folds, called wrinkles, are produced by the contraction of sub-cutaneous muscles ; 
 such as the transverse wrinkles produced by the action of the occipito-frontalis, the ver- 
 tical wrinkles by that of the corrugatores supercilii, and the radiated folds caused by the 
 contractions of the orbicularis palpebrarum, the orbicularis oris, and the sphincter ani. 
 These wrinkles, like the contraction of the muscles by which they are produced, are only 
 transitory ; but they become permanent when their causes are frequently repeated. In 
 the same class as these we must include the corrugations of the skin of the scrotum, 
 from contraction of the dartos. 
 
 The folds or wrinkles resulting from age and from emaciation depend upon the skin be 
 coming, after more or less distension, too much stretched, and, therefore, too loose to fit 
 closely to the parts beneath. Hence, emaciation in young subjects does not produce the 
 same effects as in the aged ; for in the latter, the wrinkles are caused by the want of 
 elasticity in the skin, and they are more distinct in proportion as that property is lost. 
 In cases of extreme distension, when the skin has been altered in its texture, the wrinkles 
 are more marked, and are permanent ; as, for example, those observed on the abdomen 
 of females after pregnancy, and of either sex after dropsy. 
 
 Furrows between the Papilla. — It is necessary carefully to distinguish from the folds or 
 wrinkles of the skin those more or less regular but slight furrows which exist between 
 the linear ridges or eminences formed by the cutaneous papillae in the palm of the hand 
 and the sole of the foot, and which are also found, though in a less marked degree, in all 
 other parts of the body. 
 
 Adherent Surface of the Skin. — In mammiferous animals the skin is lined throughout 
 the greater part of its extent by a layer of muscular fibres, which are intended to act 
 upon it, and constitute the cutaneous muscle or panniculus carnosus ; but in man the only 
 traces of this structure are the platysma myoides and the palmaris brevis. 
 
 The sub-cutaneous muscles of the human subject are concentrated in the face. It 
 follows, therefore, that, although in animals the passions can be expressed by move- 
 ments of the entire surface of the body, in man their expression is limited to the face. 
 It has been erroneously supposed that the phenomenon termed cutis anserina, or goose- 
 skin, a corrugated condition of the skin, in which the bulbs of the hairs are rendered 
 prominent by being forced outward, depends upon the contraction of a layer of muscular 
 fibres situated beneath the integument. But the most careful examination has demon- 
 strated no muscular fibres there ; we do not even find a dartoid tissue, such as is ob- 
 served wherever there exists a certain kind of active contractility independent of the will. 
 
 Beneath the skin of the human subject we find a layer of adipose tissue, panniculus 
 adiposus ; it varies in thickness, and is contained in the meshes formed by the fibrous 
 lamellae, which extend from the internal surface of the skin, and are then either attached 
 to the investing aponeuroses where the skin is said to be adherent, or become expanded 
 into a very thin aponeurotic membrane, called the fascia superficialis, in which case the 
 skin is movable. The quantity of sub-cutaneous adipose tissue, and the fixed or mo- 
 vable condition of the skin, have a constant and necessary relation with the functions of 
 each particular region. Thus, while adipose tissue is very abundant in the palm of the 
 hand and sole of the foot, where we always find a cushion of fat, it is never present in 
 the skin of the eyelids and penis. 
 
 When the skin over any bony eminence is required to be very movable, and at the 
 same time is exposed to continual friction, we find beneath it a sort of synovial capsule, 
 or bursa, as it is called ; some of these bursse exist at birth, and belong to the original 
 organization ; while others are accidental, and result from friction. 
 
 We must regard the sub-cutaneous adipose tissue as a dependance, or even as a con- 
 stituent part, of the integument, for it is impossible to separate one completely from the 
 other. The adipose tissue, in fact, penetrates into, and entirely fills the areolar spaces 
 in the skin. 
 
 The cutaneous vessels enter or pass out, and the cutaneous nerves penetrate at the 
 
STRUCTURE OP THE SKIN. 631 
 
 adherent surface of the skin, and more particularly opposite the areolas observed on that 
 surface ; so that whenever the skin is stripped off for a certain extent, it either sloughs 
 off, or its vitality is so greatly impaired as to be incapable of completing the process of 
 cicatrization. An accurate idea is, perhaps, not generally entertained of the enormous 
 quantity of nervous filaments and of the immense number of arteries which enter the 
 skin, or of the number of veins which issue from it. Its importance, both in a healthy and 
 in a diseased condition, is sufficiently explained by these anatomical facts regarding it. 
 
 Structure of the Skin. 
 
 The skin consists essentially of the cutis, dermis, or true skin (a, fig. 226) ; of the pa- 
 pillcR, which project upon its external surface ; of the pigmentum, or colouring matter (i') ; 
 of the lymphatic network ; and of the epidermis, or cuticle (b) ; as accessory parts, it edso 
 contains the sebaceous follicles, as well as arteries, veins, lymphatics, and nerves ; and has 
 connected to it the hairs and the nails. 
 
 The Cutis or Chorion. — The dermis, chorion, or cutis vera (a, fig. 226 ; e, fig. 227), is the 
 fundamental part or the basis of the skin ; and to it the skin owes ^ 226 
 
 its strength, extensibility, and elasticity. If the skin be regarded 
 as formed of several distinct layers, the dermis constitutes the 
 deepest of these. 
 
 The thickness of the dermis varies in different parts, but is always 
 in proportion to the amount of resistance which it is required to 
 offer. Thus, in the cranium, it is very thick and dense ; on the face, 
 generally, it is thinner than on the cranium, but not in every part 
 of the face. Compare, for example, its density and thickness in 
 the skin upon the lips with its tenuity and delicacy in that of the 
 eyelids. On the trunk it is almost twice as thick behind as in front ; 
 and upon the penis, scrotum, and mamma it is much thinner and 
 finer than upon any other part of the anterior aspect of the body. skJnofNesro. 
 
 In the limbs the dermis is much thinner on the surfaces which are turned towards the 
 median line and on the aspect of flexion, than it is on the outer side of the limbs and on 
 the aspect of extension, which are more exposed to the action of external objects. On 
 the palms of the hands and soles of the feet, which are almost incessantly in contact 
 with external objects, the dermis is very thick. 
 
 The thickness of the dermis varies in different individuals, and also according to sex 
 and age. In old persons it participates in the general atrophy of the tissues, and be- 
 comes so thin as to be somewhat translucent, and enables us in certain regions to dis- 
 tinguish beneath it the pearly aspect of the tendons, and the reddish colour of the muscles. 
 
 The dermis has a deep surface, and an epidermic or papillary surface. 
 
 The deep surface presents a number of conical depressions, the base of each of which 
 corresponds to the sub-cutaneous layer of adipose tissue, while its summit is directed 
 towards the outer surface of the skin, and is pierced with very fine openings. These 
 depressions or alveoli, which are most strongly developed in the soles of the feet and 
 palms of the hands, are filled with conical prolongations or masses of fat, which, when 
 inflamed, give rise to boils, and in a state of gangrene, constitute the slough from such 
 sores. 
 
 When examined in reference to its structure, the dermis is found to be composed of 
 bundles of ceUulo-fibrous tissue, interlaced with each other, and becoming closer and 
 closer towards its external surface : this fibrous tissue is scarcely extensible or eleistic, 
 so that the extensibility and elasticity of the skin are due, not to the nature of the der- 
 moid tissue, but to the arrangement of its component bundles.* The elasticity of a tis- 
 sue may depend, like that of caoutchouc, upon the nature of its material, or, like that of 
 a spiral piece of brass wire, may result from the arrangement of that material. The elas- 
 ticity of the skin appears to be of the latter kind. 
 
 The PapUlm. — Upon the external or epidermic surface of the cutis are found a multi- 
 tude of small eminences, which are either arranged side by side, in rows or ridges {d, 
 fig. 227), as in the palms of the hands and soles of the feet, or are irregularly scattered 
 over the surface. These eminences are called the cutaneous papilla ; together, they con- 
 stitute the papillary body {corpus papillare). To understand them properly, we must ex- 
 ami le a section of a portion of skin from the palm of the hand or the sole of the foot, 
 which section should be made transversely to the direction of the papillary ridges (see 
 fig. 227) : nimierous small eminences are then seen projecting from the dermis into the 
 substance of the epidermis, which may be distinguished from these projections by its 
 transparency and its horny appearance. The papillae are still more distinctly seen by re- 
 moving the epidermis from a piece of skin, and then examining the latter under a thin 
 layer of fluid. 
 
 The papillae consist of a spongy erectile tissue,i- containing nervous filaments, arter- 
 ies, and veins. 
 
 * The dermoid, like other cellular and fibrous tissues, is resolved into gelatine by boiling. It acquires great 
 density and strength in the process of tanning, by which it is converted into leather. 
 
 t It is impossible to doubt the analosv of the papilla; of the skin to those of the tongue, and even to the in- 
 
632 NEUROLOGY. 
 
 Tl:e nerves of the papillae are very numerous. In reference to this point, it is observed 
 that the number of nervous filaments distributed to the skin is always in a direct ratio 
 with the number and size of the cutaneous papiUae ; and hence the nerves of the skin 
 covering the palm of the hand are exceedingly numerous. 
 
 Several anatomists state that they have seen the nerves spreading out like pencils in 
 the papillae themselves.* 
 
 The papillae receive both arteries and veins ; in successful injections with mercury, 
 or with glue-size, spirit-varnish, or turpentine, coloured with vermilion, all the papillae 
 are penetrated by the injection, and exhibit, both in their interior and on their surface, a 
 vascular network, which might be called an erectile tissue. + 
 
 Lymphatics of the Skin. — If we introduce the pipe of the mercurial injecting apparatus 
 very obliquely beneath the epidermis, the mercury, if the process is successful, will run 
 into a sub-epidermic network of vessels, and will soon cover the skin with a metallic lay- 
 er. These vessels are most evidently lymphatics, for the mercury soon passes from 
 them into the sub-cutaneous lymphatic vessels, and from them into the adjacent lym- 
 phatic glands : in no case does it enter the bloodvegsels. 
 
 Mascagni, who has given so many representations of the vessels of the skin in his 
 beautiful plates, has delineated in several of them this lymphatic network, lying super- 
 ficially to the layer of bloodvessels. 
 
 The universal prejudice against microscopical observations had very improperly 
 thrown some discredit upon the positive results obtained by this great anatomist, when 
 an accidentally successful injection enabled Haase to trace and delineate the cutaneous 
 lymphatics of the groin from the skin to the inguinal glands. t M. Lauth, also, by acci- 
 dent, injected the lymphatic network of the same region. Panizza, in 1830, clearly de- 
 monstrated the arrangement of the superficial lymphatic network upon the glans penis 
 and the prepuce, in his beautiful injections of that organ in the human subject and in an- 
 imals. Lastly, M. Fohmann {Essai sur les Vaisseaux Lymphatiques do divers Ordrcs, 1833) 
 has made some special researches upon this subject, viz., upon the lymphatic network 
 in the skin and in other parts. Two beautiful plates, one representing the skin of the 
 mamma, and the other that of the scrotum, glans penis, and prepuce, give a perfect idea 
 of the arrangement of this network, which, when filled with mercury, forms a silvery 
 layer beneath the epidermis. From this network branches are given off which perforate 
 the dermis in all directions, and enter the sub-cutaneous lymphatic vessels proceeding 
 from its internal surface. We have succeeded perfectly in injecting the sub-cutaneous 
 lymphatic vessels in the entire lower extremity of a new-born infant, merely by introdu- 
 cing the pipe into the sole of the foot. 
 
 This lymphatic network is remarkable for being situated superficially to the bloodves- 
 sels, as Mascagni had correctly observed, and for being completely independent of any 
 other system of vessels ; also, for its vessels being dilated into ampullae at various pla- 
 ces, for being destitute of valves, and for not opening anywhere upon the surface of the 
 skin ; so that, excepting from laceration, the mercury does not escape through the pores 
 of the epidermis. Lastly, the network generally consists of two very distinct layers, sit- 
 uated between the epidermis and the dermis ; one extremely delicate and superficial, 
 the other lying immediately upon the dermis, and belonging to deeper vessels.^ 
 
 The Pigmentum. — All the different shades of colour observed in the skin of the sev- 
 eral races of mankind belong to either the white, the black, or the copper-coloured va- 
 riety : they depend upon the presence of a colouring matter called the pigmentum, which 
 exists in the European as well as in the negro, though in a less marked degree, and 
 which is deposited beneath the epidermis. 
 
 This colouring matter, or pigmentum (b', fig. 226 ; c, fi^. 227), may be demonstrated in 
 the skin of the negro (represented in fig. 226) with the greatest facility by means of 
 maceration. It is tlien found not to be contained in special vessels, as Bichat supposed, 
 but to be deposited beneath the epidermis, where it constitutes a uniform layer, that 
 either comes off with the epidermis or remains attached to the dermis, but is independ- 
 ent of either. II The epidermis, the papillae, and the chorion are of precisely the same 
 colour in the negro as in the white races. The pigmentum of the skin is identical in 
 
 testinal villi. Although we are unacquainted with their precise structure, it is enough to know that they are 
 composed of an erectile spong-y tissue, in which both nerves and vessels terminate. The nervous lilaraentscan 
 be traced by dissection as far as the bottom of the alveolar depressions in the dermis. 
 
 * Analysis of a former Memoir upon the Structure and Functions of the Skin, by MM. Breschet and Rous- 
 sel de Vauzfime. These authors state that they have ascertained that the nerves of the skin terminate in loops 
 or arches, as had been pointed out by MM. Prevost and Dumas, in regard to the nerves of the muscles. We 
 shall elsewhere see what is to be thought concerning the existence of thesu terminal loops of the nerves in 
 muscles, and the theory of muscular contraction founded upon it. 
 
 t [The papillae are prolongations of the vascular and nervous chorion.] 
 
 X De Vasis Cutis et Intestinorum Absorbentibus, LipsiiK, 1789. In the plate given iu this work, the lym- 
 phatic plexus is very badly represented. 
 
 ^ According to M. Fohmann, the skin is composed of the following parts proceeding from within outward : 
 1. The panniculus adiposus. 2. The internal layer of the dermis, characterized by its fibrous moshes. 3. A 
 vascular layer composed of lymphatics, and the terminations of the bloodvessels and veins, united by a small 
 quantity of animal matter. 4. A vascular network, formed exclusively by the ultimate rami ficatious of ' le lym- 
 phatics, 5. The rete mucosum of Malpighi. 0. The epidermis. !i See not« . 635. 
 
THE PIGMENTUM. 63S 
 
 every respect with the choroid pigment in the eye, and is formed of black molecules in- 
 soluble in water. Blumenbach conjectured that this black matter was nothing more 
 than carbon : several experiments appeared to confirm this opinion, but it is now gen- 
 erally believed to be formed by the colouring matter of the blood.* In the European it 
 escapes observation, because it does not differ much in colour from the epidermis and 
 dermis. 
 
 The colour of the skin, which is a matter of such interest in the natural history of 
 mankind, and which forms one of the principal characters of the several human races, 
 has a tolerably constant relation to the colour of the hair : thus, individufds with light 
 hair have generally fairer skins than such as have dark hair ; and thus, also, red hair is 
 accompanied with a somewhat analogous colour of the skin. In albinoes the colouring 
 matter is deficient in the skin, as it is in the hair, and in the interior of the eye. More- 
 over, the transition, in regard to the colour of the skin, from the white to the black races 
 of mankind, occurs through a succession of intermediate shades : thus, I have found a 
 colouring matter precisely similar to that of the negro's skin beneath the epidermis of 
 several Europeans, particularly upon the scrotum, and upon the tanned faces of those 
 who have lived exposed to a strong solar heat. In the disease called black or green 
 jaundice, the skin of white persons becomes black or olive-coloured. A superficial 
 chronic irritation produced by blisters, or certain skin diseases, or by an adjacent wound, 
 will also sometimes cause a black discoloration of the skin. 
 
 • As to the source of the pigment of the skin, it is thought by M. Gauthier that it is 
 yielded by the bulbs of the hairs. M. Breschet describes a series of glandular organs for 
 secreting this pigment, which, according to him, are situated in deep furrows in the 
 outer portion of the dermis, and are surmounted by a great number of excretory tubes, 
 from which the globules of pigment are poured out beneath the epidermis. I have never 
 been fortunate enough to ascertain the existence of these glandular organs and their ex- 
 cretory tubes. It is generally supposed that the vessels of the cutaneous papillae are the 
 source whence the pigment is derived ; the mechanism of its formation must be the 
 same as that of the formation of the choroid pigment in the eye, and it is quite as little 
 understood.* 
 
 The Epidermis. — The epidermis, or cuticle (J, fig. 226 ; a b, fig. 227), is the outermost 
 of the several layers of the skin ; it is a semi-transparent, homy layer, which is moulded 
 upon the surface of the dermis and its papillae like a coat of varnish, and protects them 
 from the action of external agents. Its internal surface is, in fact, marked by a multi- 
 tude of little pits, into each of which a papilla is received ; so that this surface of the 
 epidermis may be said to form a mould of the papillary surface of the skin. In the skin 
 of the negro, the colouring matter occupies the little pits in the epidermis, and is found 
 in greater abundance between the papillae than upon them. 
 
 In order to obtain a good view of the structure of the internal surface of the epidermis, 
 various sections may be made of the skin upon the palms of the hands and soles of the 
 feet. It will then be seen that the papillas dip, as it were, into the epidermis, which fur- 
 nishes a kind of sheath for each of them. This arrangement is exceedingly distinct in 
 the skin upon the lower surface of the bear's foot. I have alluded to this structure in 
 vay Anatomie Pathologique (-'Diseases of the Lymphatics," liv. ii.). M. Breschet has 
 recently observed it in the skin of the whale, in which animal the epidermis forms a 
 complete tube for each of the papillae. These sheaths, or tubes, are united by a gluti 
 nous matter, and may be separated, at least in the bear, with the greatest facility. 
 
 The internal surface of the epidermis is intimately adherent to the external surface oi 
 the dermis ; but this adhesion may be destroyed in the living subject by the application 
 of a blister, and after death by maceration. If in a piece of macerated skin the epider- 
 mis be carefully separated from the true skin, it will be seen that the adhesion of one to 
 the other is in part effected by a number of very delicate transparent filaments, which 
 may be stretched to the extent of several lines without breaking. On examining the in- 
 ternal surface of the epidermis imder water, these filaments are seen floated out. 
 
 What, then, is their nature 1 Are we to regard them, with Cruickshank, as prolonga- 
 tions of the epidermis which dip into the areolae of the true skin"! or, with Beclard, as 
 strings of mucus formed by the stretching out of the viscid mucous matter situated be- 
 tween the dermis and the epidermis 1 or, on the other hand, are they canals 1 and if so, 
 are they to be regarded as exhalant vessels, as Kaaw, Boerhaave, and W. Hunter be- 
 lieved'? are they exhalant and absorbent vessels too, as Chaussier and Bichat imagined? 
 or are they not, rather, special vessels, the vasa sudoris of Bidloo, and the vasa sudatoria 
 of Eichhorn, the latter of whom attributed to them both an exhalant and an absorbent 
 function 1 These questions are not yet satisfactorily solved. The very great activity, 
 both of exhalation and absorption of the skin, necessarily supposes the existence of some 
 special apparatus for these processes. 
 
 Steno, Malpighi, and others admitted the existence of certain sudoriferous glands, sit- 
 uated in the adipose cellular tissue, and consisting of tubes which opened on the exte- 
 
 * See note, p. 635 
 
 4L 
 
634 NEUROLOGY. 
 
 rior by means of an orifice provided with a valve. (Vide Holler, t. v., lib. xii., p. 42.) 
 Fig. 227. Th.\s description, when somewhat modified, agrees with the 
 
 statements recently made by M. Breschet, who has described 
 sudoriferous glands {g g, figs. 227, 228) having a saccular form, 
 and situated in the substance of the dermis. A spiral canal* 
 (h, fig. 227), proceeding from each of these sacs, traverses the 
 dermis and epidermis, and, after having made several turns, 
 opens upon the external surface of the skin (at i).t 
 
 Besides these filaments, the deep surface of the epidermis 
 presents certain irregularities, which may be felt by the finger, 
 and which, under the microscope, appear pointed like thorns ; 
 they seem to be prolongations of the epidermis, but I have not 
 been able to detennine their precise nature. 
 
 The external surface of the epidermis presents corresponding 
 folds and furrows to those already described upon the free sur- 
 face of the skin. It also has numerous orifices or pores, visi- 
 ble to the naked eye on the palms of the hands and soles of 
 the feet, and very distinctly seen by the aid of a lens. Along 
 each of the ridges formed by the rows of papillae are found a 
 series of orifices, arranged in a regular manner, and resem- 
 bling in appearance the puncta lachrymalia in the eyelids. If 
 the skin be examined with a lens during life, while the person 
 is perspiring, drops of the excreted fluid are seen to exude, 
 and form into a small globule, which is soon lost by evaporation, 
 and, after a few seconds, another globule makes its appearance. 
 It is impossible to conceive how several celebrated anatomists could have denied the 
 existence of pores in the skin. J 
 
 Delia Torre, Fontana, and Mascagni believed that the epidermis was organized, and 
 that it consisted of a network of lymphatic vessels. But as Panizza has clearly proved 
 (Osservazioni Antropo-zootomico Fisiologiche, 1830, p. 83), the lymphatic network always 
 lies beneath the epidermis, which may, by maceration, be raised up from it. After the 
 example of Panizza, I have endeavoured to inject the epidermis upon the soles of the 
 feet, and upon other parts of the body, but without being able to find a single vessel. 
 As for the opinion that the epidermis contains arterial and venous capillaries, it is so at 
 variance with the results of observation that it does not require refutation. The epi- 
 dermis, then, is unorganized [non-vascular]. 
 
 It is a product of secretion, a layer of concrete, transparent, and very hygrometric 
 mucus ; a sort of horny matter, of variable thickness, capable of reproduction after hav- 
 ing been destroyed, and the morbid alterations of which result, not from any proper vital 
 action in itself, but from a diseased condition of those living parts of the skin by which 
 it seems to be produced. 
 
 As to the structure of the epidermis, it has been repeatedly stated to consist of imbri- 
 cated scales ; but the most careful examination discloses nothing more than a layer ol 
 uniform structure, into which the papillae enter ; so that it may be decomposed, hypo- 
 thetically and even actually, by the aid of the scalpel, in some animals, into a number of 
 agglutinated tubes or sheaths, each of which belongs to a single papilla. The different 
 forms of the fragments of epidermis, detached either spontaneously or in consequence of 
 disease, depend upon accidental circumstances, and show the continuity of this mem- 
 brane in the human subject.^ I shall presently describe the relations of the epidermis to 
 the hair, the nails, and the sebaceous follicles. 
 
 * Fontana had previously spoken of serpentine vessels, which he had seen beneath the epidermis by meaua 
 of the microscope. 
 
 + [The sudoriferous glands, discovered by Breschet, Purldnj6, and Wendt, may be seen best by examining 
 under the microscope a thin perpendicular section of a piece of skin taken from the palm of the hand (as ia 
 fig. 227), and hardened in a solution of carbonate of potash. They are situated in the sub-cutaneous adipose 
 cellular tissue (/) ; they consist of a long convoluted tube (or of two tubes which unite together), ending in an 
 efferent duct (A), which opens (i) upon the free surface of the epidermis, and is lined by flattened epidermic 
 corpuscules. Where the epidermis is thin, these ducts are nearly straight, as in the scalp (see Jig. 228), and 
 their orifices are scattered irregularly over the surface ; where it is thick, they have a spiral course, as in the 
 palm and sole (fig. 227), where their orifices are arranged in single rows on the papillary ridges. These spi- 
 ral ducts are turned in opposite directions on the right and left extremities ; the average number of their ori- 
 fices is fifty in the square line ; the filaments described in the text as connecting the epidermis to the dermis 
 are the epidermic linings drawn out of these ducts, and out of the sebaceous and piliferous follicles.] 
 
 i See note, p. supra. 
 
 [^ The epideiTuic portion of the skin has been so long supposed to consist of several distinct structures, that 
 it is still convenient to describe separately an epidermis, a pigmentum, and a rete mucosuni ; but modern re- 
 search has shown that these are merely different layers of the same structure, in different stages of develop- 
 ment. The most superficial and hardest of these layers, which is separated from the skin in vesication during 
 life, and by maceration after death, is the epidermis described in the text, and by authors generally ; the 
 deeper, more recently formed, and softer portions, which may be displayed and subdivided into several layers 
 by maceration and dissection, constitute the pigmentum and the rete mucosum : together, these insensible, 
 extra-vascular, but not inorganic layers, form what is now called the epidermis. 
 
 Thus defined, the epidermis exactly resembles the epithelium of mucous membranes, in consisting of a 
 number of adherent nucleated corpuscules, each of which undergoes an independent development. Ininiedi 
 
APPENDAGES OF THE SKIN. '"635 
 
 According to M. Breschet, certain minute reddish glands are situated among the sub- 
 cutaneous adipose vesicles, and constitute the secreting apparatus of the epidermis. Ex- 
 cretory ducts are said by him to proceed from the summits of these small glands, to trav- 
 erse the dermis, and to open at the bottom of the furrows found upon its external sur- 
 face. According to the same observer, these ducts generally resemble rows of regular- 
 ly-arranged columns, and the glands are sometimes situated at unequal depths from the 
 surface, and communicate with each other by intermediate ducts. I have never suc- 
 ceeded in verifying these observations ; and I have equally failed in attempting to decom- 
 pose the epidermis into a series of layers, becoming less and less compact in proportion 
 to their distance from the surface. 
 
 The Corpus Mucosum, or Corpus Reticulaire of Malpighi. — Malpighi applied the term 
 reticulum, and others, following that great anatomist, have given the names corpus retic- 
 ulaire, corpus mucosum, and rete mucosum, to a gelatiniform layer {d, fig. 227) of what is 
 regarded as a concrete mucus, situated beneath the epidermis and perforated by the pa- 
 pillae, which thus give it a reticulated appearance. This inorganic [non-vascular] layer, 
 which Malpighi first demonstrated beneath the thick epithelium of the tongue of the ox, 
 after it had been boiled, and which he then supposed to exist also in the skin, cannot be 
 demonstrated anatomically ; so that the expressions corpus mucosum, corpus reticulaire, 
 have lost their original signification, and have been interpreted in a different sense. 
 Haller, and several anatomists quoted by him, regarded the corpus mucosum as a deep 
 layer of the epidermis, some of them confounding it with the pigmentum, and others dis- 
 tinguishing it from that body. Bichat considered the corpus mucosum to be an extreme- 
 ly delicate network of vessels, or system of capillaries, which formed, with the papillae, 
 an intermediate layer between the chorion and epidermis, and was partly intended to 
 convey the blood, and partly the colouring matter of the skin. 
 
 M. Gauthier, in examining the skin of the heel in the negro, recognised four distinct 
 layers in the corpus mucosum, arranged in the following manner, from within outward : 
 1. Vascular processes containing red blood {bourgeons sanguins), which are situated upon 
 and adhere to the papillae ; 2. A deep white layer, composed of serous vessels, and 
 moulded upon the vascular processes and papillae ; 3. A layer of gemmules, forming a 
 kind of coloured membrane, excavated upon its deep surface, and separated from the 
 vascular processes and papillae by the deep white layer ; 4. A superficial white layer, 
 which he regards as formed of serous vessels, as well as the deep white layer. Exter- 
 nally to this is the epidermis. M. Dutrochet, founding his opinion upon the examination 
 of the skins of quadrupeds, admits the different layers of M. Gauthier, excepting the vas- 
 cular processes, which he very properly regards as forming parts of the papillfe : he 
 calls the deep white layer of M. Gauthier the epidermic inembrane, the gemmules he terms 
 the coloured layer, and the superficial white layer he names the horny layer. 
 
 Lastly, Gall regarded the corpus mucosum as a layer of gray nervous matter, precisely 
 similar to that of the gray substance of the brain and of the nervous ganglia. 
 
 I agree with Chaussier that we ought altogether to reject the corpus mucosum, in 
 whatever sense that term may be understood ; and I believe there are good grounds for 
 supposing that the different layers described as forming this body belong, in reality, some 
 to the papillae, and others to the epidermis.* 
 
 Appendages of the Skin. 
 
 Under this title may be included the sebaceous follicles and the homy growths, viz., 
 the nails and hairs. 
 
 The Sebaceous Follicles. — The skin contains within its substance certain sebaceous fol- 
 licles {i i, fig. 228) ; these consist of small pouches, or bags, about the size of a millet 
 seed, which form projections beyond the epidermis, but are lodged in the substance of the 
 dermis, and open externally by very small orifices, which are visible under a lens, and, 
 in some persons, even to the naked eye. From these orifices an unctuous matter is con- 
 stantly poured out upon the surface of the skin, and assists in preserving its pliability ; 
 in some individuals this unctuous matter may be expressed from the follicles upon the 
 
 ately upon the surface of the true skin, these corpuscules are soft, roundish vesicles, containing a distinct nu- 
 cleus and peculiar pigment granules, and adhering together by a viscid matter, the cytoblastema, in which 
 they are first developed. In approaching the surface of the cuticle, they become larger and more compressed, 
 their walls become thicker and denser, their nuclei less distinct, and their pigment paler, until, at length, they 
 form thethin, flattened, horny, nucleated, colourless discs, whicli, adhering to each other firmly in an imbricated 
 manner, constitute the upper and horny portion of the epidermis, from the free surface of which they are con- 
 stantly being thrown off as minute scales, to be continually replaced by others having a similar origin, and un- 
 dergoing the same changes : these imbricated scales were described by Leuwenhoek and Baker. 
 
 The epidermis is insoluble, even in boiling water ; but it swells and becomes softened and transparent, in 
 these respects resembling mucus and epithelium ; it consists of a substance called keratin. 
 
 The pigment granules contained in the deeper epidermic corpuscules are the cause of the colour in the 
 skin ; they are black in the negro, &c., of lighter hues in other dark races, and fawn-coloured in the Euro- 
 pean ; in all cases they are darlcest in the deeper and newly-formed corpuscules, and fade as these approach 
 the surface : in albinoes they are either absent or colourless. The pigment contains iron and carbon, both in 
 a combined state, phosphate of lime, and animal matter ; but as it is bleached by chlorine, it contains no free 
 carbon, as supposed by some.] 
 
 * See note, p. 634. 
 
636 
 
 NEUROLOGY. 
 
 Section of skin from the head, 
 magnified 14 times. 
 
 Fig. 228. alae of the nose, in masses which look like small worms. 
 
 These sebaceous follicles are somewhat analogous to 
 the follicles of the mucous membranes ; they are not 
 found in the palms of the hands and soles of the feet ; 
 but, in all probability, they exist in every part of the 
 body : they are especially observed in the axilla, on the 
 hairy scalp, and around the margins of the anus and 
 vulva, and the openings of the nose and mouth : they 
 are very much developed in the new-bom infant. The 
 sebaceous follicles appear to me to have a glaiidular 
 structure ; and this is particularly evident in those of 
 the axilla, the organization of which seems to me to be 
 more complex than that of those found in other parts 
 The supposition that these follicles are formed by the 
 reflection of the thin portion of the skin is altogether 
 fanciful.* 
 
 The Nails and the Hair. — In man the horny growths 
 of the skin are less developed than in any animal expo- 
 sed to similar atmospheric conditions ; and in man, also, 
 we find the highest development of the sense of touch. 
 The nails of the human subject are hard, yet flexible 
 and elastic, semi-transparent scales, and present the ap- 
 pearance of laminae of horn : they are situated upon the dorsal surface of the last phalan- 
 ges, which are therefore called the ungual phalanges ; and they appear rather to be in- 
 tended for the support and protection of the pulpy extremities of the*ngers. than as weap- 
 ons of attack, or instruments of defence and prehension. In a state of civilization it is 
 customary, therefore, to cut ofl!'that part of the nail which projects beyond the end of the 
 finger. The ingenuity of man enables him to provide himself with oflfensive M^eapons 
 amply sufficient to compensate for the weakness of those provided by nature, which, in- 
 deed, are quite rudimentary in him, and if more fiilly developed, would greatly interfere 
 with the delicacy of his sense of touch. 
 
 The peculiarity of the human nail consists in its only covering the dorsal surface of the 
 last phalanx, and in its being of considerable breadth, corresponding, in this respect, with 
 the horseshoe-like enlargement at the end of the phalanx. It follows from this, that the 
 whole of the pulp of the finger is concerned in the exercise of the sense of touch, t 
 
 The nail is divided into the root, the body, and the free portion : the root is that part of 
 the nail which is covered on both surfaces ; the body is that part which has one sur- 
 face free ; while the third, or entirely /rec portion, projects beyond the end of the finger, 
 and has a tendency to become incurvated when left to grow naturally. 
 
 In order to obtain a correct idea of the anatomy of the nails, we should, by a longitu 
 dinal incision, make a vertical section of the ungual portion of one of the fingers (see fig. 
 229). We shall then perceive that the root is about one fourth of the length of the body 
 of the nail (J) ; that it is also the thinnest part of the nail ; that it diminishes in thick- 
 ness towards its posterior edge, which is slightly indented, and that it increases towards 
 the body of the nail ; that it is flexible, and is received into a duplicature of the skin (c 
 c), to which it is attached by both surfaces ; that the posterior edge and lower surface of 
 the root adhere so slightly to the skin, that they may be said to be merely applied to it ; 
 that the upper surface of the root, though it adheres more closely to the skin than the 
 lower surface, is yet much less firmly attached to it than the under surface of the body 
 of the nail, which cannot be torn off without great violence ; that the nail is separated 
 from the phalanx by a very thick dermis (c') ; that this skin is of a white colour at the 
 root of the nail, and for some distance in front of it, where it occasions a semilunar 
 white mark, visible through the transparent nail, and called the lunule (lunula) ; and, lastly, 
 that the dermis, which corresponds to the body of the nail, is extremely vascular, and 
 hence the nail has a rosy hue, because its semi-transparency enables us to perceive the 
 colour of the subjacent tissue. 
 
 One of the most important points in the anatomy of the nail is the nature of its con- 
 nexion with the dermis. The fold of the skin, which is called the matrix of the nail, is 
 Ibrmed in the following manner : the skin (c, fig. 229, being the dermis) is prolonged 
 
 * [The sebaceous glands (t't, _/5^. 228) are mtiltilocular follicles; their ducts are lined by epi.lennic cor- 
 puscules, and open upon the surface of the skin in parts without hairs ; where hairs exist, they open into the 
 hair follicles (c), to each of which two sebaceous glands (it) are generally attached. On the face, very nii- 
 B^ite hairs have been found around the orifices of the ducts of these glands : their secretion is albuminous as 
 well as fatty.] 
 
 t The hoof, of which a very perfect example is met in the horse, is nothing more than a nail which enclo- 
 ses the united phalanges on all sides, like the wooden shoes sometimes worn ; the claw of carnivorous animals 
 is a nail which covers two thirds of the slender ungual phalanx, is compressed at the sides, and terminates in 
 a pointed hook. The nail, properly so called, is found only in man and in quadrumana, and in the latter it 
 approaches in ch.aracter to the claw. The division of mammalia into ungulatcd and unsrniciila'pd is exceed- 
 ingly natural, and is, in some measure, represented by certain correlative and constant differences in all other 
 Darts of the system. — (See Anatomic Comparee de M. de Jilainville.) 
 
THE APPENDAGES OF THE SKIN. $^ 
 
 from the finger on to the dorsal suiface of the nail, as far 
 as the curved line that marks the posterior boundary o! 
 the body of the nail ; from thence it is reflected b;ick- 
 ward, folded upon itself, as far as the posterior bonlrr 
 of the root of the nail. At this point it is again reflected 
 forward upon itself by passing behind that border, and 
 then (c' c') between the under surface of the nail and th'i 
 dorsal aspect of the phalanx : in consequence of this two- 
 fold reflection, it follows that it is always the epidennic ^"''°" "'"'='" "^ *"»'• 
 surface of the true skin that is in contact with the nail : at the anterior extremity of the 
 nail the skin again meets, as it were, the epidermis (a'), and becomes continuous with 
 the integument upon the tip of the finger. But what is the arrangement of the epider- 
 mis at the point where the skin is first reflected backward 1 It is prolonged forward 
 (a), slightly beyond the curved line formed by the reflection of the dermis, and forms a 
 semicircular zone or band, which terminates by a smooth border, and jidheres intimately 
 to the nail. As to its arrangement beyond this point authors are not agreed. Some are 
 of opinion that it would be prolonged upon the free surface of the nail, if it were not de- 
 stroyed by friction ; but they overlook an objection to this view to be derived from the 
 accustomed regularity of the epidermic border : others, again, believe that the epidermis 
 is reflected backward like the dermis, but differ among themselves cis to its ultimate dis 
 position ; some, for example, conceiving, with Bichat, that tlie epidermis is continuous 
 with the posterior border of the nail, and some supposing that it is again reflected for 
 ward beneath the nail, together with the dermis (see dotted line), which, according to 
 this hypothesis, it never quits.* 
 
 A very simple experiment most clearly demonstrates the nature of the connexion be- 
 tween the epidermis and the nail : it consists in submitting a finger to the process of 
 maceration, by means of which the nail and epidermis come off together in the form of 
 a partly epidermic and partly horny sheath. In this the epidermis (a) is found to be re- 
 flected backward upon the dorsal surface of the root of the nail, and to become blended 
 with it (see fig. 229) without ever passing beyond its posterior border ; while in front, at 
 the limits between the body and the free portion of the nail, the epidermis (a') is mani- 
 festly continuous with the deepest layer of the homy lamina ; so that it cannot be doubt- 
 ed that there is an identity of nature between the nail and epidermis. 
 
 Structure and Growth of the Nail. — On examining the two surfaces of the nail, and es- 
 pecially its deep surface and posterior border, it is found that they are marked by very 
 distinct longitudinal lines or striae, which appear to indicate a corresponding linear tex- 
 ture. It would seem, accordingly, that the nail was formed by the agglutination into 
 laminae of a number of longitudinal fibres ; but, if we examine the free surface of the nail 
 attentively, we find that it is marked by curved striae, which intersect the longitudinal 
 ones. These curved striae are particularly distinct in the not uncommon cases in which 
 the nail of the great toe is much hypertrophied, and becomes incurvated upon the plantar 
 surface of the toe : the enlarged nail is found to consist of imbricated laminae, received 
 one into the other like the several laminae in the hoof of an animal. We may even sep- 
 arate these different layers by aid of maceration, and find that they are fitted one into 
 the other, the deepest being that which was last secreted. The nails, therefore, are 
 developed by a method very analogous to that by which we have already stated the teeth 
 are formed. (See p. 179.) 
 
 The nails, then, like the hoofs of animals, and like the epidermis, are products of se- 
 cretion : they receive neither vessels nor nerves : alterations in their texture are not de- 
 pendant upon diseases inherent in themselves, but result from some morbid condition of 
 their formative organ. The fold of the dermis, which is called the matrix of the nail, is 
 not the only part by which the substance of the nail is secreted, but the whole papillary 
 surface of the dermis, to which the nail adheres, is concerned in its formation. The 
 papillae are ananged in longitudinal rows, and hence the substance of the nail is depos- 
 ited in longitudinal striae. -f 
 
 The nail grows continually in length ; it does not increase sensibly in thickness, ex- 
 cepting during disease. The layers that have been deposited the longest time are the 
 most superficial, and occupy the free extremity of the nail, in precisely the same manner 
 as the oldest-formed ivory in the tooth is nearest to the enamel.t 
 
 * See note t, below. 
 
 f The arrangement of the papillary dermoid layer which covers the dorsal surface ot the ungual phalanx 
 IS worthy of notice : it adheres intimately to the periosteum, and forms an extremely dense, grayish stratum, 
 penetrated by vessels and nerves ; so that, if the mode of termination of the nerves in the papillse c.an ever be as- 
 certained, it is, without doubt, beneath the nail, where these papillae present their highest state of development. 
 
 t [The nails are found by Schwann to consist of nucleated corpuscles, which, like those of the epidermis, 
 are formed upon the surface of the dermis, where they are soft and vesicular, and afterward become hard, 
 flattened, and firmly agglutinated together, as in the substance of the nail. These corpuscles are developed, 
 not only opposite the matrix of the nail, but beneath the whole of its attached surface ; the nail is thus elon- 
 gated, and, at the same time, its thickness is maintained, notwithstanding the flattening of the corpuscles 
 formed at the root as they approach the surface. The thin layer of epidermis, described by Weber, Lauth, 
 and Gurlt, as continued under the whole attached surface of the nail, is nothing more than the soft stratum 
 of growing corpuscles, which pass insensibly into those of the true epidermis. 
 
 Like the epidermis, the nails consist of keratin.} 
 
638 NEUROLOGY. 
 
 The Hairs. — The hairs are filiform productions of tiie epidermis, generally flexible, va- 
 riable in length, size, and colour, and bearing different names, according to the region on 
 which they are situated.* 
 
 The surface of the human body, with the exception of the palms of the hands and the 
 soles of the feet, is covered by very fine and short hairs, which form a light down, as it 
 is named ; but the hairs, properly so called, are collected upon particular parts of the sur- 
 face of the body, where they serve some special purpose. Thus, they exist in great 
 abundance upon the cranium, where they are called the hair ; on the face, where they 
 form the whiskers and beard ; the hairs upon the margins of the eyelids are called the eye- 
 lashes ; the arched row over each orbit is called the eyebrow ; the hairs upon the lips con- 
 stitute the mustache. 
 
 On the trunk the hairs are collected, in more or less abundance, around the genital or- 
 gans : they exist, also, in the axillae of both sexes ; and on the chest, between the breasts, 
 in the male. The hairs present well-marked differences, according to sex, age, and the 
 peculiar race to which the individual belongs. The pilous system is most developed in 
 the Caucasian race, and least so in the negro. 
 
 The hair, eyelashes, and eyebrows exist before birth : before birth, also, the whole 
 body is clothed with a very thick down, which is shed during the first few months after- 
 ward. At the period of puberty, hairs are developed upon the pubic region, and in the 
 axillae of both sexes, upon the labia majora of the female, and upon the scrotum and 
 around the anal orifice in the male : the beard also appears in the male, and the ante- 
 rior aspect of the trunk, and the limbs are covered with hairs of variable length in dif- 
 ferent persons. I should observe, that the development of the hairs is not always in 
 proportion to the personal strength, as is asserted by certain authors, who regard an 
 abundance of hair as an attribute of strength and virility. But, although some men with 
 hairy skins have robust constitutions, a great number are delicate, and are even affected 
 with tubercular phthisis. 
 
 In mammalia, the hairs upon the posterior or dorsal region of the trunk are more de- 
 veloped than those upon the anterior or abdominal aspect, a proof that they are destined 
 to the quadruped attitude : in some animals, which turn upon their backs to protect them- 
 selves, the hairs upon the abdominal surface are most highly developed. 
 
 The hair of the head may grow to a very considerable length : it has been seen to reach 
 as low down as the middle of the leg, and, when thrown around the trunk, sufficiently 
 abundant to cover it like a garment. The length and the direction of the hair upon the 
 head evidently prove that man is destined for the erect posture ; for, if he assumed the 
 attitude of a quadruped, it would trail upon the ground, and fall over the face. 
 
 The hair also presents peculiarities, or differences, in many respects ; for example, in 
 direction, some hair being long and smooth, some crisped and woolly ; this latter kind is 
 peculiar to the negro race, and it never grows to a very great length : also in diameter, 
 some hair being excessively fine, and some large and coarse. t It differs, again, as to 
 quantity, for, in general, the hair of the head is more abundant in the female than in the 
 male, as if the activity of the pilous system was principally confined to the hairy scalp 
 in the former sex ; and, lastly, in its colour, from which certain very important distinc- 
 tions among men are established. 
 
 Every different shade in the colour of the hair may be referred to three principal va- 
 rieties, the black, the flaxen, and the red. The flaxen hair belongs particularly to the 
 inhabitants of the north, and to persons of lymphatic and sanguineous temperaments ; 
 the black is characteristic of the inhabitants of the south, and of those of a bilious and 
 sanguineous temperament ; the red belongs to no particular temperament ; and in our 
 ideas of beauty, this coloured hair, which is usually accompanied with a disagreeable 
 odour of the perspiration, is regarded as a natural misfortune. 
 
 The beard and whiskers are peculiar to the male sex ; they occupy the lower part of 
 the face, and, consequently, leave uncovered all those parts which are principally con- 
 cerned in giving expression to the physiognomy, viz., the ocular, nasal, and frontal re- 
 gions. We cannot insist too strongly on the connexion existing between the develop- 
 ment of the genital organs and that of the beard. The eunuch is almost destitute of 
 that appendage. 
 
 The great attention rendered necessary by wearing a long beard and long hair has led 
 to the custom of cutting the hair and shaving. It is remarkable that the most effemi- 
 nate nations, the Orientals, for example, are those among whom long beards are in high- 
 est estimation. The influence of these different customs upon the health are deservedly 
 subjects of examination for those who study Hygiene. 
 
 Structure and Growth of Hairs. — The only method of obtaining an accurate knowledge 
 of the structure of hairs is to study their growth. The extremity of the hair which is 
 inserted into the skin is contained in a sort of follicle, very analogous to the dental folli- 
 
 * The spines of the hedgehog, the bristles of the boar, the hair of horses, the wool of sheep, and the fur of 
 most mammalia, are different kinds of hair. 
 
 t [The hair of the head also varies in its form; a section being a more or less flattened oval, or even reni 
 form, from the hair being excavated along one side. On the face, the hairs are still more flattened.] 
 
THE ORGAN OF TASTE. 639 
 
 '.les. Tliis hair-follicle (e,fig. 230), which is the formative organ of 
 -lie hair, is imbedded in the sub-cutaneous cellular tissue (g), and is 
 prolonged to the surface of the skin by a sort of meinbranous canal, 
 which was well described by Bichat. The hair-follicles consist es- 
 sentially of a pouch or sac, and a papilla. 
 
 The membranous pouch or sac (c c), called the bursal membrane 
 by Heusinger, forms a sort of cul-de-sac, having a narrow neck, and 
 opening externally by a contracted orifice, through which the hair 
 (A) passes without adhering to it at all. Its walls are sufficiently 
 transparent to allow the hair contained in its cavity to be seen. If 
 this cavity or sac, which, according to M. Dutrochet, is formed 
 merely by the inversion of a portion of the skin, be laid open, its in- 
 ternal surface (c) is found to be smooth, not adherent to the hair, but 
 separated from it by a reddish liquid, first pointed out by Heusinger. Magnmrf." 
 
 From the bottom of this sac, i. e., from the part farthest from the orifice through which 
 the hair protrudes, a papilla (a), called the pulp of the hair, arises : this papilla is of a 
 conical form, its base being adherent, while its apex is free ; it reaches nearly to the 
 orifice of the sac, and even projects beyond it in the disease called plica polonica. 
 Bloodvessels and nerves pass to the bottom of the hair-follicle, and are probably distrib- 
 uted upon the papilla. 
 
 It is upon the papilla that the hair is formed. At its commencement it resembles a 
 conical horny sheath, which is exactly moulded upon the apex of the papilla. On the in- 
 ner side of this horny cone another is formed, which raises up the preceding one, and 
 so on in succession, the entire hair constantly maintaining a conical form. According 
 to the experiments of Heusinger, who plucked out at intervals the hairs from the whis- 
 kers of a dog, and afterward killed the animal, so as to observe the successive changes 
 which took place in the hair-follicles during the development of the new hairs, a rather 
 long period elapses before the hair projects beyond the epidermis ; but, when once it has 
 overcome that obstruction, its growth proceeds rapidly. 
 
 What is the arrangement of the epidermis at the point where the hair emerges beyond 
 its surface 1 According to some, it is prolonged upon the hair, and forms its outer coat ; 
 according to others, it dips into the cavity of the hair-follicle, and is reflected upon the 
 base of the hair, so as to form upon it an epidermic tube, which falls off in scales as the 
 hair is prolonged outward ; according to others, again, the epidermis has no connexion 
 with the hair ; and I am the more inclined to subscribe to such an opinion, because the 
 hair is of the same size both before and after it has left the follicle.* 
 
 The hair is the product of a secretion, and, therefore, destitute of vitality, being form- 
 ed by a series of small horny cones fitted one into the other. It is generally admitted 
 that it is composed of a homy, colourless, transparent, epidermoid sheath, containing a 
 sort of coloured pith in its interior. Bichat presumed that this central substance was 
 formed of certain bloodvessels which contained the colouring matter ; but the mode in 
 wiiich the hair is developed proves that it is not tubular, and also that the colouring 
 matter itself is produced by the papilla at the same time as the epidermoid sheath. The 
 white hairs of old people are merely deprived of colouring matter. + 
 
 The Organ of Taste. 
 
 The structure of the tongue, the organ of taste, which has already been described (see 
 j). 332), presents a greater analogy to that of the skin than any other of the organs of 
 liio senses. 
 
 Tlie sense of taste resides essentially in the papillary membrane which covers the up- 
 i>or surface of the tongue. t It has already been stated that the perforated eminences 
 found at the base of the tongue are not papillae, but glands ; and the true papillae have 
 been divided into the large or cahciform papillae, which are arranged in the shape of the 
 lettov V at the base of the tongue, and the small papillae ; which may be again subdivided 
 iiiro the conical, the filiform, and the lenticular or fungiform, according to their respect- 
 iv shapes. 
 
 i>ery special sense, by which term is understood ail such as receive sensations dif- 
 ftrent from that of touch, properly so called, presents for our consideration a special ap- 
 
 *■ rThe root of some hairs is larger than the shaft, and is named the bulb ; this, however, does not depend 
 (.u thu hair being covered by the epidermis, a thin layer of which (d d,fig. 230) lines the follicles, and is be- 
 liiivdd to terminate at the root of the hair. Into each hair-foUicle one or more sebaceous glands (i i,fig' 227) 
 ;i.n;r tlieir secretion.] 
 
 t Lllairs, like the nails, consist, according to recent researches, of nucleated corpuscles, which differ in 
 U.xm, density, and arrangement, in different parts of the hair. At the root, upon the surface of the papilla, 
 »h: re they are first developed, they are soft and vesicular ; in the central medullary part of the shaft they are 
 b:inkr, compressed, and polyhedral ; in the cortical part they form an immense number of very long and fine 
 liiirrs, and, on the outside of these, a layer of short, hard scales. 
 
 The hairs consist principally of keratin and an oily matter ; besides which, they yield sulphur, phosphorus, 
 iron, salts of lime, and traces of manganese, silica, and magnesia.] 
 
 X [The mucous membrane on the under surface of the tongue, and that covering the buccal surface of the 
 soft palate and the immediately adjacent parts of the fauces, also possess the sense of taste.] 
 
649 NEUROLOGY. 
 
 paratus, on which the impressions act, and a special nerve or nerves, adapted to receive 
 those impressions and transmit them to the brain. 
 
 The nmscular structure of the tongue, which at first sight appears to be useful only in 
 mastication, deglutition, and the articulation of sounds, is intimately connected with the 
 sense of taste, which would have been exceedingly imperfect, had not the gustatory 
 membrane been capable of being moved over the bodies to be tasted. The gustatory 
 apparatus of the tongue consists, then, of a papillary membrane stretched over a muscu- 
 lar surface, and united so closely to it that it is impossible to separate one from the oth- 
 er. Moreover, this membrane is constantly kept in a state of humidity, and occupies 
 the first cavity presented by the digestive apparatus. 
 
 The Gustatory Papillary Membrane. — All the elements of the skin are found in the gus- 
 tatory membrane. 
 
 The chorion is as dense as the densest part of the chorion of the skin : a very great 
 number of muscular fibres are inserted into it, so that the gustatory membrane can be 
 moved not only as a whole, but each part of it has its own separate movements. 
 
 The papilla, by which the surface of the tongue is rendered so rough, may be said to 
 represent the papillary body of the skin in a very highly-developed state.* 
 
 The lingual papilla are supplied with nerves, which can be more easily shown than 
 those in the cutaneous papillee. Haller has traced them into the papilla; ; and I have suc- 
 ceeded in doing the same, but without being able to ascertain their mode of termination. 
 
 The papillae also receive bloodvessels, which are so abundant that, in successful injec- 
 tions, the papillary body appears to be altogether vascular. 
 
 The Lymphatic Network. — By making a superficial puncture into any part of the mem- 
 brane which covers the dorsum or the borders of the tongue, we may inject a lymphatic 
 network upon it, precisely similar to that found in the skin. 
 
 The mucous body, or rete mucosum, does not exist as a distinct membrane upon the 
 tongue any more than in the skin. I have already stated that it was while examining 
 the boiled tongue of the ox that Malpighi discovered a glutinous stratum situated be- 
 tween the epidermis and the papillae, and perforated by a number of openings, corre- 
 sponding to that of the papillae themselves ; hence the name of reticulum which he gave 
 it ;t but it is as impossible to demonstrate it upon the tongue as in the skin. 
 
 The Pigmentum. — There is never any black colouring matter in the tongue of the hu- 
 man subject ; but it is distinct upon the tongue of some animals, as the ox, and can be 
 easily demonstrated between the papillae and the epithelium.t 
 
 The Epithelium. — Each papilla is covered with a sort of epidermic sheath, which, ac- 
 cording to Haller, was discovered by Mery and Cowper, and which has been perfectly 
 described by Albinus under the name of the periglottis. This epidermis, or epithelium, 
 so easy of demonstration in the lower animals, in which it has the consistence of horn, 
 may be also readily shown in the human subject, although, in accordance with the great- 
 er perfection of the sense of taste in man, the epithelium is comparatively thin. If the 
 upper surface of the tongue be examined with a lens, especially after maceration, the 
 lingual epithelium will be seen to be arranged in precisely the same manner as the epi- 
 dermis of the skin, and to form a protecting sheath for each papilla. In persons who 
 have sunk after long abstinence, the epithelial covering forms several imbricated layers, 
 which can be rubbed off; the fur which adheres to the tongue is in a great measure 
 formed by this debris of the epithelium somewhat dried. The epithelium of the tongue 
 can be removed by friction ; and, in certain inflammatory diseases, the tongue is denuded 
 of it. When one of the lingual papillae is thus exposed, it becomes excessively painful. 
 
 The Nerves of the Tongue. — No other organ, perhaps, of equal size, receives so many 
 nerves as the tongue : one pair, the ninth or hypoglossal, is exclusively appropriated to 
 it ; and it also receives, on each side, the glosso-pharyngeal branch of the eighth, and 
 the lingual branch of the fifth of the cerebral nerves. Which of these nerves must be 
 regarded as the nerve of taste in the tongue 1 Evidently the one that is distributed to 
 the papillae. On this account, since the time of Galen, the lingual branch of the fifth 
 pair, or the lingual nerve, as it is called, has been regarded as the gustatory nerve ; 
 though it would seem more natural to admit, with Boerhaave, that the hypoglossal nerve, 
 which is distributed exclusively to the tongue, should, as it were, preside over the spe- 
 cial sense situated in this organ. But the lingual nerve is found to enter the tongue at 
 its corresponding border, and to spread out into branches which pass vertically upward, 
 and are exclusively distributed to the papillary membrane of the anterior, or free portion 
 of the tongue. 
 
 The ninth or hypoglossal nerve of each side runs from behind forward, between the ge- 
 nio-glossus and stylo-glossus muscles, and communicates with the lingual nerve, so as 
 to form the lingual plexus. It is not certain that some of the filaments of the hypoglos- 
 
 * If the epidennic tubes, which are so remarkably distinct on the foot of the bear, be removed from the pa- 
 pillae, the latter, when exposed, exactly resemble those of the tongue.] 
 
 t " Hanc fabricam a Malpighio inventam, et a Bellino libenter acceptam, scriptores anatomicorum, et phys- 
 iologicorum operum iconibus etiam pictis expresserunt." — {Haller, t. v., lib. xiii., p. 107.) 
 
 t [The pigment in these cases, and the lingual rete mucosum also, are the lowermost layers of the ectra 
 vascular squamous epithelium.] 
 
THE NOSE» 641 
 
 sal nerve do not reach the papillae ; but there is no doubt but that almost all of them are 
 
 lost in the intrinsic muscles of the tongue. 
 
 The right and left glosso-pharyngeal nerves supply the base of the tongue, and are ex- 
 clusively distributed to the mucous membrane covering that part. No filament of the 
 glosso-pharyngeal nerve is intended for the muscular fibres ; and it is a remarkable fact, 
 that in one case in which the facial nerve sent a branch to the tongue supplementary to 
 the glosso-pharyngejd, that branch was distributed precisely in the same manner as the 
 glosso-pharyngeal itself; that is, it was exclusively distributed to the mucous membrane 
 at the base of the tongue. From what is stated above, then, it is anatomically shown 
 that the lingual branch of the fifth nerve and the glosso-pharyngeal nerve are the specijil 
 nerves of the tongue.* 
 
 The following case is no less demonstrative of the same fact ; Anf individual had com- 
 plete paralysis of the right half of the tongue. That side of the tongue became atrophied, 
 and had scarcely one third of its natural thickness. Both its tactile and gustative sen- 
 sibiUty were equally acute on the two sides of the organ. After the death of the person 
 thus afflicted, an acephalo-cyst was found in the right posterior condyloid foramen, which 
 had caused a complete atrophy of the right hypoglossal nerve. The corresponding half 
 of the tongue had undergone the fatty degeneration. 
 
 The Organ of Smell. 
 
 The organ of smell is situated in a cavity formed within the bones of the face, as, in- 
 deed, are most of the other senses ; it is placed at the entrance of the respiratory pas- 
 sages, and above the organ of taste, with which it has many points of relation. Although 
 situated in the median line, it is a double organ. It consists of an external apparatus, 
 which serves to protect the organ, to keep it in the necessary state of moisture for the 
 proper exercise of its functions, and to direct the air towards that part of it which is en- 
 dowed with the greatest olfactory sensibility : this is the nose, properly so called. 
 
 And, secondly, of two complicated and winding cavities, the nasal fossa, lined by a 
 mucous membrane, cedled the pituitary membrane, which is the essential seat of the sense 
 of smell. 
 
 The J^ose. 
 
 The nose resembles in form a three-sided pyramid, directed vertically, and projecting 
 from the middle of the face, so that the olfactory organ is the most anterior of all the or- 
 gans of the special senses. 
 
 Its numerous varieties in shape and size fall under the consideration of painters rather 
 than anatomists ; for these varieties have greater effect upon the physiognomy than upon 
 the exercise of its functions. 
 
 On each side of the nose, at its lower part, is observed a semicircular furrow, having 
 its concavity directed downward, and forming the upper border of the alse nasi ; from 
 this furrow, on either side, the naso-labial furrow of the semeiologists commences. The 
 lateral surfaces of the nose form, by their union, the dorsum, which is either straight, 
 convex, or concave, according to the subject ; differences which, in a great measure, 
 determine the national or individual forms of this part of the face. The term lobe of the 
 nose is applied to the rounded eminence in which the dorsum nasi terminates below. 
 
 The summit, or root of the nose, is separated from the nasal protuberance by a trans- 
 verse furrow. The base of the nose presents two elliptical or semilunar orifices, called 
 the nostrils (jiares) : the long diameters of these two orifices are directed horizontally 
 backward and outward, and they are separated from each other by an antero-posterior 
 septum ; they are provided with stiff" hairs, or vibrissce, which serve to arrest any small 
 particles floating in the air.t 
 
 The direction of the nostrils is a proof that the erect position is natural to man ; for, 
 if he were to assume the attitude of a quadruped, only the dorsum of the nose would be 
 directed towards odoriferous bodies. The situation of the nostrils above the orifice of 
 the mouth explains how no ^llimentary substance can be introduced into that cavity 
 without having been previously examined by the sense of smell. 
 
 The nose consists of a skeleton or basis, and of certain muscles ; it is covered by the 
 skin externally, and by a mucous membrane internally ; and it receives both vessels and 
 nerves. 
 
 The Structure of the Nose. 
 The basis or framework of the nose is composed of bone, cartilage, and fibrous tissue. 
 
 * [The result of the vast number of experiments and observations made upon this subject, by persons of op- 
 posite opinions, would appear to be, that the lingual nerve (a branch of the fifth), and the lingual portion of 
 the glosso-pharyngeal nerves, are both of them gustatory nerves, and also nerves of ordinary sensibility to the 
 tongue. The portion of the palate and fauces endowed with the sense of taste derives its power from the pal- 
 atine nerves, which are given off from a gangUon (Meckel's) connected with the second division of the fifth 
 nerve.] 
 
 t This use of the vibrissse becomes very evident in serious diseases ; when, in consequence of the humed 
 respiration, dry particles floating in the air become attached like a fine powder to these hairs. The coUectioo 
 of particles of dust around the nostrils often warns the practitioner of the serious nature of a disease 
 
 4M 
 
642 NEUROLOGY. 
 
 The osseous portion occupies the upper part of the organ, and consists of the proper 
 nasal bones, and of the ciscending processes of the superior maxillary bones. 
 
 The cartilaginous part consists of the two lateral cartilages of the nose, to which we may 
 add the cartilage of the septum, although it rather forms part of the nasal fossae than of 
 the nose properly so called ; and, secondly, of the two alar cartilages, or cartilages of the 
 nostrils, making five in all. To this we must add certain cartilaginous nod^iles, situated 
 between the lower part of the cartilages of the alae and that of the septum. Santorini 
 described eleven cartilages in the nose, doubtless because he reckoned certain cartila- 
 ginous nodules, which are sometimes accidentally developed in the substance of the 
 fibrous tissue.* 
 
 The fibrous portion of the nose consists of a fibrous layer, which occupies the interval 
 between the lateral 'cartilages of the nose and the cartilages of the alae. 
 
 From this structure, it follows that the nose is inflexible above, flexible in the middle, 
 and extremely movable below. This arrangement has the threefold advantage of pro- 
 viding against fractures of the most prominent part of the nose, of permitting the dilata- 
 tion of the nostrils, and, lastly, in consequence of the solidity of the highest and narrow- 
 est part of the n2isal fossae, of ensuring a free passage to the air. 
 The lateral cartilages of the nose (a a, fig. 231) are of a triangular form ; and they are 
 Fig. 231. united together along their anterior margins, which are thick above, so 
 as to form a sharp ridge, which constitutes the dorsum of the nose. 
 Along the line of union there is a sort of furrow or groove, which can 
 be felt even through the skin. By their upper and posterior margins, 
 they are articulated with the nasal bones ; I say articulated, because 
 there is no continuity of substance, but the parts are connected by 
 fibrous tissue, which allows a considerable degree of motion. Their 
 lower margins are convex, and correspond in front to the cartilages of 
 the alae of the nose, and behind to the fibrous tissue which occupies the 
 intervals between the cartilages. The lateral cartilages are intimately 
 united with the cartilage of the septum, along the dorsum of the nose ; 
 so that we might regard these three pieces as forming a single cartilage. 
 The thickest part of each lateral cartilage is above and in front. 
 The cartilages of the nostrils are generally called, after Bichat, the filro-cartilages of 
 the alcR of the nose ; but we have already seen that some of the fibro-cartilages of Bichat 
 are thin layers of ordinary cartilage, while others consist merely of condensed fibrous 
 tissue. The so-called fibro-cartilages of the nostrils belong to the former kind. There 
 is but a single cartilage on each side {b b,fig. 231) for the ala nasi, the lobe, and the in- 
 ferior portion of the septum ; it consists of an irregular lamina folded upon itself into a 
 semi-ellipse or parabola, opening behind. We shall examine its external and internal 
 portions. 
 
 The external portion (b) is extremely thin, and corresponds to the ala of the nose ; it is 
 not situated in the substance of the ala, but is placed above it, so that its lower margin 
 corresponds to the curved furrow which forms the upper boundary of the ala.t 
 
 The internal portion (b,fig. 232) is thicker than the external, and is situated upon a 
 lower plane than it : it corresponds, on the inside, to the internal portion of the cartilage 
 of the opposite side, from which it is separated above by the cartilage of the septum. 
 The internal portions of the two alar cartilages are separated from each other by some 
 rather loose cellular tissue, which allows them to move upon each other, and also per- 
 mits the cartilage of the septum to extend between them, without interfering with them 
 at all. The internal portions of the cartilages of the alae do not reach the anterior nasal 
 spine, but terminate abruptly at a certain distance from it, by forming a projection, which 
 is very distinct, especially in some individuals, and which sensibly elevates the mucous 
 membrane at the entrance of the nostrils. At the point of union between the internal 
 and external portions of each alar cartilage, that is to say, at the summit of the parabola, 
 the cartilage itself becomes wider and excavated behind, and assists in forming the lobe 
 of the nose. The margins of these cartilages are irregularly notched or scolloped. The 
 upper margins are united to the other cartilages by means of a fibrous tissue, which al- 
 lows them to move frgely, both upon the cartilage of the septum and upon the lateral 
 cartilages of the nose. 
 
 A small cartilaginous nodule is found on either side, between the lobe of the nose and 
 the cartilage of the septum ; the only use of these nodules is to facilitate the movements 
 of the lobe upon the septum. 
 
 The cartilage of the septum nasi (c,fig. 232) occupies the triangular interval between 
 
 the perpendicular plate of the ethmoid bone and the vomer. It consists of two parts : 
 
 one, wide and free, which is that generally described ; the other, which is narrow, and 
 
 may be called the caudal prolongation of the cartilage, is received into the bony portion 
 
 • of the septum, between the two lamellae of the vomer 
 
 * See note, infra. 
 
 t [Two or three cartilaginous nodules (e e,fig. 231) are generally found appended in a curved line to the 
 posterior extremity of this portion of the cartilage of the ala.l 
 
THE PITUITARY MEMBRANE. 643 
 
 The fret portion of the cartilage is thick and triangular ; it has 
 the same direction as the bony septum, and presents two lateral 
 surfaces, covered by the pituitary membrane ; an anterior margin, 
 of which the upper half (c, fg. 231) is blended with the lateral 
 cartilages along the dorsum of the nose, while its lower half is 
 free, convex, directed downward, and received between the two 
 cartilages of the nostrils ; a superior and posterir margin, which is 
 extremely thick and rough, and is intimately united to the corre- 
 sponding margin of the perpendicular plate of the ethmoid bone 
 (e, Jig. 232) : the mode in which this union is effected is not by 
 articulation, but by a continuity of tissue, like that between the 
 costal cartilages and the ribs ; lastly, an inferior margin, which is 
 received between the two plates of the vomer (»). The groove 
 into which it is received is very deep ; and as the two plates of 
 the vomer become more and more separated in extending forward, so does the corre- 
 sponding margin of the cartileige increase in thickness ; hence the lower extremity of 
 the septum frequently projects considerably into one or other of the nostrils. 
 
 The caudal prolongation of the cartilage of the septum may be seen by carefully exani 
 ining the retreating angle formed by the perpendicular plate of the ethmoid and the vo- 
 mer ; in which situation the cartilage of the septum gives off a considerable prolonga- 
 tion, in the form of a band, which occupies the interval between the two plates of the 
 vomer, and is attached to the rostrum of the sphenoid bone. This cartilaginous band is 
 contained entirely within the substance of the middle portion of the bony septum : its 
 upper margin is thin, and, as it were, toothed ; the lower margin is thick and rounded. 
 The two naso-palatine nerves are situated in the same canal as the cartilage, and are 
 placed one on each side of it. 
 
 The muscles of the nose are the pyTamid2ilis nasi, the levator labii superioris alaeque 
 nasi, and the transversalis nasi, or compressor narium, which we have described as a 
 dependance of the depressor alae nasi, or rayrtiformis : an accurate description of these 
 muscles is still to be desired. 
 
 The skin covering the nasal bones and the lateral cartilages of the nose has no par- 
 ticular character : it is thin and movable. That which covers the alae and the lobe of 
 the nose is very thick and extremely dense ; it crepitates under the knife, to such a de- 
 gree, that cartilages have been supposed to exist in the substance of the alae. We have 
 seen, however, that the cartilages of the nostrils are not prolonged into the alae, which 
 are composed essentially of the dense integument just described, and which is reflected 
 inward upon itself around the margins of the nostrils. 
 
 I should remark, that the antero-posterior diameter of the opening of each nostril is 
 much less than that of the corresponding cartilage ; this depends upon the fact that the 
 skin is prolonged anteriorly, and is reflected for some lines below and behind the lower 
 margin of the cartilage. 
 
 The skin of the nose is remarkable for the great development of its sebaceous follicles. 
 The orifices of these follicles are shown in many individuals by certain black points, 
 which are nothing more than the sebaceous matter discoloured. When forced out of 
 the follicles by lateral pressure, the masses of sebaceous matter resemble in form small 
 worms. 
 
 The skin, which is reflected upon itself around the margins of the nostrils, preserves 
 the character of integument as far as where it is provided with hairs, and then suddenly 
 assumes the characters of mucous membranes. 
 
 The Pituitary Membrane. 
 
 The pituitary or Schneiderian* membrane, the immediate seat of smell, is a fibro-mucous 
 membrane, which lines the whole extent of the nasal fossae, and is prolonged, with some 
 modifications of texture, into the different cells and sinuses which open into those fossae. 
 
 When covered with this membrane, the nasal fossae present a configuration differing 
 in many respects from that which they have in the skeleton. Many of the foramina and 
 canals are closed, and several are contracted in their dimensions. The irregularities 
 of the surface of the turbinated bones are, in some measure, concealed. Besides this, 
 the mucous membrane, where it is reflected upon itself, forms a number of folds, some 
 of which prolong the turns of the turbinated bones ; while others, more or less, contract 
 the orifices of communication between the various cells and sinuses and the nasal fossae. 
 
 The pituitary membrane, originating, then, on the one hand, from the skin, which is 
 reflected at the margins of the nares, and provided with hairs {h,Jig. 233), is, on the other 
 hand, continuous, without any line of demarcation, with the mucous membranes of the 
 pharynx and velum palati (at t s), of the Eustachian tubes (at m), and of the nasal ducts 
 (at r). In the roof of each nasal fossa {u v) it closes the foramina of the cribriform plate 
 
 * Conrad Victor Schneider (de Caiarrho) gave his name to this membrane, because he was the first to refute 
 •nccessfuUy the erroneous notion of the ancients, that the secretion of the nasal fossae descended from llie ven 
 tricles of the brain ; the common term cold in the head still remains as a vestig-e of this error 
 
644 
 
 NEUROLOGY. 
 
 Fig. 233. 
 
 of the ethmoid bone, and those of the nasal bones, so that all the vessels and nerves 
 which pass through these foramina enter the mucous membrane by its external surface ; 
 before it enters into the sphenoidal sinus, it forms a fold around the orifice of that sinus, 
 by which the opening is narrowed, so as to have the form of a vertical fissure (see the 
 bristle marked d). 
 Upon the external wall of each nasal fossa (see Jig. 233)* it covers a great number of 
 
 parts, counting from below upward, viz., the 
 inferior meatus, at the upper and anterior part 
 of which it meets with the lower orifice of 
 the nasal duct {r,figs. 233, 234) ; around this 
 opening it forms a semilunar valvular fold, 
 the free margin of which is directed down- 
 ward, and which prolongs the canal of the 
 ducts to a greater or less distance in differ- 
 ent subjects ; in passing a probe into the na- 
 sal duct from the inferior meatus, this valve 
 must, almost of necessity, be torn. 
 
 From the inferior meatus the pituitary 
 ttiembrane is reflected upon the inferior tux' 
 hinated bone (c c,figs. 233, 234), which appears 
 longer in the recent state, in consequence 
 of a fold of the mucous membrane being con- 
 tkiued in front, and another still more marked behind the bone : this is the thickest part 
 of the nasal mucous membrane. 
 
 In the middle meatus (t) the pituitary membrane covers the infundibulum, at tlie lower 
 extremity of which is an ampulla or dilatation, where the orifice of the maxillary sinus is 
 generally found. This orifice (see bristle a, fig. 234) has a very different appearance 
 from that which it presents in the dried scull : it is extremely narrow, scarcely admit- 
 ting the blunt end of a common probe. It sometimes appears as if it were wanting ; 
 but it will then be found opposite the middle of the infundibulum ; in this case, the max- 
 illary sinus might be said to communicate directly with the frontal sinus. Not unfre- 
 quently the maxillary sinus opens both into the middle meatus and the infundibulum 
 The pituitary membrane is prolonged from the infundibulum into the anterior ethmoidal 
 cells (c e, fig. 234), and into the frontal and maxillary (m m) sinuses. If we remove the 
 middle turbinated bone, we find a considerable projection, which bounds the infundibu- 
 lum above (n, fig. 233), and corresponds to a large ethmoidal cell. Upon, the back part 
 of this projection, on which the middle turbinated bone is moulded, an opening (see bris- 
 tle) is often found leading into this great cell, and on its fore part (at e), one or more or- 
 ifices leading into the anterior and superior ethmoidal cells. 
 
 From the middle turbinated bone {b, figs. 233, 234), which is continued backward hy 
 
 a fold of the membrane, the pituitary membrane 
 passes into the superior meatus, where I have fre- 
 quently met with four or five openings leading into 
 as many of the posterior ethmoidal cells, which, in 
 this case, did not communicate with each other : I 
 have even seen the orifice of an ethmoidal cell upon 
 the superior turbinated bone (a). 
 
 The pituitary membrane dips into all the etlimoid- 
 al cells, and into the frontal sinuses, either directly 
 or indirectly, but it does not enter the spheno-pala- 
 tine foramen, which, on the contrary, is completely 
 closed by it. 
 
 Upon the septum the pituitary membrane is remark- 
 able for its thickness, being exceeded in this respect 
 only by the membrane covering the inferior turbinated bone. We do not find in man 
 that prolongation or cul-de-sac, which is so very distinct in some animals, in front of 
 the lower border of the septum ; but at this point the pituitary membrane closes the 
 two superior orifices of the anterior palatine canal. 
 
 Structure. — The pituitary membrane is a mucous membrane, and its peculiarity con- 
 sists in its being extended over osseous and cartilaginous surfaces. Its free surface is 
 smooth, red, and scattered over with foramina, from which a great quantity of mucus 
 maybe expressed. + Its adherent surface is intimately united to the periosteum and 
 perichondrium of the bones and cartilages of the nasal fossee, so that it is classed among 
 the fibro-mucous membranes. 
 
 * [In this figure, portions of the middle and inferior conchse are represented as cut away, to show the parts 
 m the middle and inferior meatuses.] 
 
 t [In the nasal fossa; the epithelium of the pituitary membrane is columnar and ciliated ; in the sinuses it 
 approaches the squamous in character, but yet it is provided with cilia, the movements of which have been 
 obserTed in the lower animals to produce currents towards the openings of the respective sinuses.] 
 
 Fig. 234. 
 
THE ORGANS OF SIGHT. 645 
 
 The pituitary membrane is generally thicker than the other mucous membranes, so 
 that it is very easy to determine the highly vascular and truly erectile structure of this 
 membrane. If it be punctured, and the tube of a mercurial injecting apparatus intro- 
 duced, the mercury w^ill immediately enter the cells of the erectile tissue, and from 
 thence pass into the veins arising from those cells. If a more superficial puncture be 
 made, a lymphatic network will be injected, situated so superficially, that the mercury 
 exhibits all its metallic lustre. This lymphatic network has no communication with the 
 venous cells just mentioned.* 
 
 This lymphatic network, which is common to all the mucous membranes, gives to the 
 non-vascular layer by which they are covered the appearance of a serous membrane. 
 
 The pituitary membrane receives a great number of arteries, which penetrate it by sev- 
 eral points, and which are almost all derived from the same source, viz., the internal 
 maxillary artery ; as, for example, the spheno-palatine, the infra-orbital, the superior al- 
 veolar, the palatine, and the pterygo-palatine. Some arise from the ophthalmic arterj', 
 viz., the supra-orbital and the ethmoidal ; and others from the facial artery, viz., the dor- 
 salis nasi, the artery of the alae, and the artery of the septum. 
 
 The capillary veins are so numerous, that they in a great measure form the basis of 
 the pituitary membrane ; the larger veins which proceed from them follow the course of 
 the arteries, and enter, by very large trunks, into the internal maxillary, the facial, and 
 the ophthalmic veins. There are numerous communications between these last-named 
 veins and those of the ethmoidal region of the base of the cranium. 
 
 The spongy character of the internal surface of the nasal fossae, and more particularly 
 of the surface of the turbinated bones, is due to certain grooves and foramina intended 
 for the reception and transmission of bloodvessels. 
 
 I am only acquainted with the superficial lymphatic network already noticed. In order 
 to inject it, it is necessary to scratch the membrane with the injecting pipe. 
 
 Are there any glands or follicles in the pituitary membrane 1 Steno has described cer- 
 tain glands which I have not been able to find. The follicles in this membrane are rather 
 difficult to be shown. 
 
 Like all the organs of the special senses, the pituitary membrane is provided vdth a 
 special nerve, called the olfactory, the nerves of the two sides constituting the first pair 
 of cerebral nerves. Comparative anatomy shows that the development of the olfactory 
 nerves is in relation with the development of the sense of smell, and thus establishes, in 
 a most positive manner, the generally-received opinion regarding the function of this pair 
 of nerves. Without entering here into the description of the olfactory nerves, which 
 will be given hereafter, I would observe, that they pass through the foramina and canals 
 of the cribriform plate of the ethmoid bone, at the same time becoming enveloped in 
 fibrous sheaths ; that they enter the pituitary membrane by its external surface ; and 
 that they expand into a plexus in its substance. The branches of these nerves cannot 
 be traced lovi-er than the middle turbinated bones on the one hand, and the middle of the 
 septum on the other. Thus, while the upper and extremely narrow part of each nasal 
 fossa {s,fig. 234) is the essential seat of the sense of smell, the lower and much wider 
 part only gives passage to the air during the act of respiration. 
 
 Besides the special nerve of smell, the pituitary membrane receives other nervous fil- 
 aments, all of which are derived from branches of the fifth nerve, viz., from the internal 
 nasal and the frontal branches of the ophthalmic division of that nerve, and from the 
 spheno-palatine, the great palatine, the vidian, and the anterior dental branches of its 
 second or superior maxillary division. The experiments of modern physiologists have 
 shown that the integrity of these different branches of the fifth pair is necessary for the 
 perfect possession of the olfactory sense. This, however, is very different from saying 
 that the seat of that sense is in the branches of the fifth pair. 
 
 The membrane which lines the several sinuses, although it is continuous with the pi- 
 tuitary membrane, does not resemble it in character ; it is exceedingly thin and trans- 
 parent, and appears like a serous rather than a mucous membrane ; that it is a mucous 
 membrane, is satisfactorily established only by certain pathological f3,cts. The mucous 
 membrane of the sinuses has a very close resemblance to the conjunctiva.t 
 
 The Organs of Sight. . 
 
 The eyes, or the organs of sight, are situated at the highest part of the face, so that 
 they are enabled to explore objects at a distance. 
 
 They are two in number ; but they co-operate in their function so as to act like a sin- 
 gle organ. The result of this is, that vision is rendered more certain, and its field of 
 operation more extensive, at the same time that, from the unity of action of both eyes, 
 it is single. 
 
 The eyes are protected by the orbital cavities in which they are contained ; they are 
 covered by the eyelids, and these are surmounted by the eyebrows. They are surround- 
 ed by six muscles, by which they can be moved in all directions ; they are divided into 
 
 * It was in the pituitary membrane of the calf that, about ei jht vears ago, I first accidentally injected th*- 
 tuperficial lymphatic network. ' " t See note, p. 648. 
 
646 NEUROLOGY. 
 
 the straight and the oblique muscles. There is also a secreting a{5paratus,tKeapparafti# 
 of the lachrymal passages, the secretion from which lubricates the anterior surface of the 
 ball of the eye, and facilitates the exercise of its functions. 
 
 The study of the organ of sight, therefore, is not limited to that of the eyes alone, 
 but includes that of the means of protection, viz., the orbital cavities (see Osteology), 
 the eyelids, and the eyebrows ; that of the muscles, or moving organs ; and that of the 
 lachrymal passages, or lubricating apparatus. These accessory parts, or appendages of 
 the organ of vision, have been collectively named by Haller the tutamina oculi. We shall 
 commence our description with them. 
 
 The Eyebrows. 
 
 The eyebrmjos are two arched ridges, which are covered with short stiff hairs, that are 
 directed from within outward, and overlap each other ; the eyebrows are situated at 
 the lower part of the forehead, and form the boundary of the upper eyelid. Their direc- 
 tion corresponds precisely with that of the orbital arch. The hairs upon them are more 
 numerous, and longer at the inner extremity, which is called the head, than at the outer, 
 which is denominated the tail of the eyebrow. The heads of the two eyebrows are sep- 
 arated from each other by an interval which corresponds to the root of the nose ; some- 
 times, however, they are blended together. 
 
 Structure. — The skin in which the hairs of the eyebrow are implanted is thick, and 
 very closely united beneath to a muscular layer formed by the frontalis, the orbicularis 
 palpebrarum, and the corrugator supercilii, the last-named muscle being situated beneath 
 the other two. The orbital and superciliary arches serve as a basis to support the eye- 
 brows ; the nerves of these parts are very numerous, and are derived from the facial and 
 the fifth nerves ; their vessels arise from the ophthalmic and temporal arteries. 
 
 Uses. — The eyebrows, which give a peculiar character to the human countenance, pro- 
 tect the eye, and, when depressed in front of it, intercept a great number of the rays of 
 light ; they assist in a remarkable degree in giving expression to the face. 
 
 The Eyelids. 
 
 The eyelids are two movable and protecting curtains, placed in front of the ball of each 
 eye, which they conceal or leave uncovered, according as they are in a state of approx- 
 imation or separation. 
 
 The eyelids are two in number — a superior and an inferior. In a great number of ani- 
 mals there is a third eyelid, of which merely a trace exists in man. The eyelids are 
 large enough to close the base of the orbit completely, and to intercept entirely the pas- 
 sage of light. 
 
 Each of the eyelids presents for our consideration a cutaneous surface, which is con- 
 vex, and marked with concentric semilunar folds that become effaced when the lids are 
 closed ; an ocular surface {fig. 235), which is concave, is accurately moulded upon the 
 ball of the eye, and presents a series of yellowish vertical lines, formed, as we shall see, 
 by the Meibomian glands ; an adherent border, which is indicated by the orbital arch in 
 the upper eyelid, but is less clearly defined in the lower lid, in which it is continuous 
 with the cheek ; lastly, a free border, or margin, which, in both eyelids, is straight when 
 the lids are closed, and curved when they are open : in the latter position they enclose 
 an elliptical space {rima palpebrarum), the dimensions of which vary in different persons, 
 and hence give rise to the expressions large eyes and small eyes, which have no refer- 
 ence to the actual size of the globe of the eye, but merely to the size of that part which 
 is exposed to view. The free margins of the eyelids are not cut obliquely from before 
 backward, so as to intercept, when they are closed, a three-sided interval or channel, 
 which is completed behind by the globe of the eye, and which is supposed to become 
 larger from without inward, in order to conduct the tears towards the larchrymal punc- 
 ta. On the contrary, these margins are cut horizontally from before backward (see sec- 
 tion,^^. 240) ; and when approximated, they leave a narrow fissure between them, which 
 may serve as a channel for the tears during sleep, quite as well as the three-sided canal 
 which is generally supposed to exist. 
 
 The margins of the eyelids, moreover, are tolerably thick, and are ftirnished at their 
 anterior hp with three or four rows of hard, stiff, and curved hairs, which are more nu- 
 merous and longer on the upper than on the lower eyelid, and at the middle than at either 
 end of each : these are the eyelashes. Their direction is worthy of notice : in the upper 
 eyelid they are at first directed downward, and are then curved upward, so as to de- 
 scribe an arc having its concavity turned upward ; the eyelashes of the lower lid have 
 just the opposite arrangement. From this it follows, that the convexities of the eye- 
 lashes of the two lids are turned towards each other ; and thus, when the eye is shut, 
 they touch each other without being able to interlace. Serious inconvenience is pro- 
 duced when the eyelashes deviate from their proper course, and are turned inward ; 
 When the eyelashes are wanting, the free margins of the lids are attacked with chronic 
 inflammation. Along the posterior lip of the free margin of each eyelid, or, rather, along 
 the angular ridge formed by the union of that margin with the posterior surface of the 
 
THE EYELIDS. Q47 
 
 lid, are placed a very regular series of foramina {figs. 235, 236), from which the sebace 
 ous matter secreted by the Meibomian glands may be expressed in masses having the 
 form of small worms. 
 
 At the junction of the external five sixths with the internal sixth of the free margins 
 of the two eyelids are found two very remarkable tubercles, the lachrymal papillcB or tu- 
 bercles {a,fi^. 239 ; also seen in/^«. 235, 236), each of which is perforated by an open- 
 ing, visible to the naked eye ; these openings are the puncta lachrymalia, the orifices 
 of the corresponding lachrymal canals. That part of the free margin of each eyelid 
 which is on the inner side of the corresponding lachrymal papilla is straight, rounded, 
 and destitute of hairs or follicular orifices : in the space enclosed between this part of 
 the eyelids, and called lacv^ lachrytnalis, is situated the caruncula lachrymalis (*, fig. 239). 
 The upper eyelid, moreover, is twice as deep as the lower ; so that, when depressed, 
 it descends below the transverse diameter, or equator of the eye, to use an expression 
 invented by Haller. • 
 
 The terms angles of the eye, or commissures of the eyelids, are applied to the angles 
 formed by the junction of the extremities of the free margins of the eyelids. The ex- 
 ternal angle, external or temporal commissure (b, fig. 239), is also named the little angle 
 (canthus minor).* 
 
 The internal angle, internal or nasal commissure (e), improperly cedled the great angle 
 of the eye {canthus major), corresponds to the posterior border of the ascending process ol 
 the superior maxillary bone. 
 
 Structure of the Eyelids. — ^The constituent parts of the eyelids are, the tarsal cartilages, 
 a fibrous membrane, a muscular layer, two integumentary layers, one mucous and the 
 other cutaneous, and certain follicles, with vessels, nerves, and cellular tissue. 
 
 The tarsal cartilages, which resemble in their use the cylinders of wood attached to 
 the bottom of a map or diagram, to prevent it from hanging in folds, are two in number, 
 one for each eyelid ; they are cartilaginous plates, situated within the free margin and 
 the contiguous portion of the lids. The tarsal cartilage of the upper eyelid (a, figs. 235, 
 236) is semilunar ; that of the lower eyelid {h) has the form of a small, narrow band ; 
 neither of them occupies the entire length of the corresponding lid. Their anterior sur- 
 face is convex, and is covered by the fibres of the orbicularis palpebrarum muscle. Their 
 posterior surface {fig. 235) corresponds to the conjunctiva, and is closely adherent to it. 
 The Meibomian glands are situated between the conjunctiva and the cartilage, or, rath- 
 er, in the substance of the cartilage. 
 
 The adherent border of each tarsal cartilage is thin, and affords attachment to the 
 fibrous membrane of the lids ; the adherent border of the cartilage of the upper eyelid, 
 which is convex, also gives attachment to the levator palpebrae superioris muscle. The 
 free margins of these cartilages are their thickest parts, and occasion the thickness of 
 the free margins of the eyelids, t 
 
 The cutaneous layer is remarkable for its excessive tenuity and semi-transparency : 
 the eyelashes are appendages of this part of the integument. 
 
 The cellular layer is no less remarkable for the absence of fat than for its extreme 
 delicacy : it is the type, indeed, of serous cellular tissue, and is frequently the seat of 
 serous infiltrations. 
 
 The muscular layer is formed by the palpebral portion of the, orbicularis muscle, the 
 pale colour of which, as I have already noticed, contrasts with the dark-red hue of the 
 orbital portion of the same muscle. Besides this, the upper eyelid has an extrinsic mus- 
 cle, the levator palpebrce superioris {a, fig. 237), the tendon of which, however, is alone 
 concerned in the formation of that eyelid, by being attached to the upper border of the 
 corresponding tarsal cartilage. 
 
 The fibrous layer consists of a fibrous membrane, which arises from the margin of the 
 orbit, and is attached to the corresponding borders of the tarsal cartilages. This mem- 
 brane is very strong and unyielding in the outer half of the base of the orbit, but dimin- 
 ishes in thickness towards the inner half of that base, especially on the inner portion of 
 the upper eyelid, where it degenerates into cellular tissue. 
 
 The term ligament of the external canthus might be applied to a fibrous raphe, which 
 extends horizontally from that angle to the base of the orbit. This raphe bifurcates op- 
 posite the outer canthus, so as to become attached to the outer end of each tarsal car- 
 tilage, and it exactly corresponds to the tendon of the orbicularis palpebrarum, which is 
 situated at the inner canthus, and which is also bifurcated, to join the inner ends of the 
 same cartilages. 
 
 (hi cutting through this raphe, some very strong fibrous bundles are exposed, which 
 arise from the external wall of the orbit, and spread out into the substance of the upper 
 eyelid. 
 
 * The external commissure does not correspond to the outer extremity of the transverse diameter of th* 
 base of the orbit, but is situated about three lines nearer to the nose ; hence the necessity of dividing this 
 commissure in extirpation of the eye. 
 
 t [The substance of the tarsal cartilages differs from that of ordinary cartilage in being more opaque, and 
 also in having a few microscopic filaments scattered through it ; in this respect approaching in character to 
 fibro-cartilage.] 
 
648 NEUROLOGY. 
 
 The expanded tendon of the levator palpebrae superioris, which is subjacent to the 
 fibrous layer, completes the fibrous structure of the upper eyelid. The tarsal cartilages 
 and the fibrous layer are situated upon the same plane. 
 
 The mucous layer, or palpebral conjunctiva, consists of a membrane which lines the 
 posterior surface {fig. 235) of the eyelids, and is, moreover, extended over the globe of 
 tig. 235. the eye. This membrane is called the conjunctiva, or tunica 
 
 adnata, because it connects the eyelids with the ball of the eye. 
 In order to facilitate our description, we shall suppose it to 
 commence at the free margin of the upper eyelid (a', fig. 240), 
 where it is continuous with the skin : having covered the whole 
 thickness of this margin, it then lines the posterior surface of 
 the tarsal cartilage (c'), to which it is intimately adherent, and 
 continues in the same direction as far as beneath the orbital 
 arch. At this point it is refldfcted upon the anterior surface of 
 the globe of the eye, so as to form a cul-de-sac between that organ and the eyelid : upon 
 the eyeball, where it is called the ocular conjunctiva, it adheres to the sclerotic coat by 
 means of cellular tissue, which is at first loose, but gradually becomes closer and closer as 
 it approaches the transparent cornea. Upon the cornea (d') its adhesion is so intimate 
 that some anatomists have denied its existence in that situation. In fact, it can only be 
 anatomically demonstrated in the healthy state upon the margin of the cornea, but its ex- 
 istence over the whole of that part of the eye is shown in some diseases. After having 
 covered the anterior and inferior part of the sclerotic (c"), the conjunctiva is reflected 
 upon the posterior surface of the lower eyelid (b'), lines its tarsal cartilage, covers its 
 free margin, and then becomes continuous with the skin. On the inner side of the ball 
 of the eye the conjunctiva forms a small semilunar fold, the plica semilunaris (e, figs. 
 235, 239), which has its concavity turned outward, and which may be regarded as the 
 vestige of the third eyelid found in animals : it is misnamed the membrana nictitans (la 
 membrane clignotante). On the outer side, the conjunctiva dips between the eyelids 
 and the ball of the eye, and forms a deep cul-de-sac. Opposite the lachrymal papillae 
 the conjunctiva passes into the puncta, and Hues the lachrymal passages. 
 
 From what has been stated above, it will be seen that the conjunctiva would form a 
 shut sac, like the serous membranes, if the eyelids were supposed to be united. Like 
 the serous membranes, it covers two surfaces that rub one upon the other. Its tenuity, 
 its transparency, and the filamentous adhesions which are sometimes observed between 
 its contiguous surfaces, have induced some anatomists to place this membrane among 
 the serous rather than the mucous membranes ; but its continuity with the skin, its ex- 
 treme vascularity, and its uses, which require it to be in contact with the air, prove that 
 it should be retained among the latter class of membranes.* 
 
 The glands found in the eyelids consist of an appendage of the lachrymal gland, which 
 will be described with it, of the Meibomian glands, and of the caruncula lachrymalis. 
 The Meibomian glands (m m, fig. 236) are situated upon the posterior surface of both 
 Fig. 236. eyelids, opposite the tarsal cartilages ; they resemble yellowish 
 
 vertical and parallel lines, sometimes straight and sometimes 
 curved ; their length is proportioned to the depth of the cartilages, 
 and they never project upon the inner surface of the eyelids. Each 
 of these lines, of which there are from thirty to forty in each eye- 
 lid, consists of a tortuous canal, folded upon itself a great number 
 of times, and having a considerable number of small follicles open- 
 ing into it on each side. All these canals open very regularly upon 
 the posterior lip of the free margin of the lid by a row of orifices 
 arranged in a single line. I have never seen two rows of openings, as Zinn states he 
 has observed. If the eyelids be compressed over the tarsal cartilages by a pair of pin- 
 cers, masses of a waxy substance exude from these orifices, having the form of small 
 worms twisted frequently upon themselves. Sometimes these small linear canals com- 
 municate with each other opposite the adherent border of the tarsal cartilage ; at other 
 times they bifurcate. It is the waxy sercetion from the Meibomian glands which pre- 
 vents the tears from trickling in front of the eyehds. These glands are lodged in the 
 deep grooves in the tarsal cartilages ; they are, therefore, as visible upon the external 
 as the internal surface of the cartilages. 
 
 The Meibomian glands belong to the class of sebaceous follicles, and form a transition, 
 as it were, from follicles to glands. 
 
 The caruncula lachrymalis {c,fig. 235,* fig. 239) consists of a small, oblong group of 
 follicles, situated at the inner angle of the eyelids, and on the inner side of that semilu- 
 nar fold of the conjunctiva, which we have spoken of as the trace of a third eyelid. It 
 is about the size of a grain of wheat. It is interposed between the free margins of 
 
 * The absence of villi has been stated as characteristic of the conjunctiva ; but villi or papillae are found 
 ■pon that portion which lines the superior tarsal cartilage. 
 
 [The epithelium of the conjunctiva is squamous, and consists of several layers : according to Henl6, it i* 
 ciliated upon the inner surface of the eyelid ; but cilia have not been observed upon the eyeball.] 
 
THE MUSCLES OF THE EYE. 6^ 
 
 tiie eyelids, in that part of those margins which extends between the lachrymal tuber- 
 cles and the internal commissure ; but it is upon a plane posterior to these margins, so 
 that it does not prevent their mutual contact. It is covered by a fold of the conjunctiva, 
 which gives it a reddish aspect ; it presents a great number of openings, through which 
 a waxy secretion exudes, and projecting from it are several small hairs, which may be- 
 come so long as to produce ophthalmia. The caruncula lachrymalis is composed of se- 
 baceous follicular glands, of the same nature as the Meibomian glands. It was for a 
 long time considered to be a second lachrymal gland. In order to obtain a good view 
 of the orifices, and of the light-coloured and sometimes very numerous hairs of the carun- 
 cula lachrymalis, that body should be covered with ink or a solution of carmine, and 
 then examined with a lens. 
 
 Vessels and. Nerves of the Eyelids. — The arteries are the internal and external palpe- 
 bral branches of the ophthalmic, and the palpebral branches of the temporal, infra-orbital, 
 and facial arteries. I have already said that the palpebral arteries form two arches, one 
 for each eyelid. 
 
 The veins have the same name, follow the same direction, and open into the corre- 
 sponding venous trunks. 
 
 The nerves are derived from two sources, viz., the facial and the fifth nerve. 
 
 Uses. — The eyelids protect the eye from the action of light and air, and of any parti- 
 cles floating in the latter ; by a sweeping movement, they clean the surface of the or- 
 gan, over which they also spread the lachrymal fluid, which serves as a protection to the 
 eyeball against the action of the air. The eyelids, from their capability of being inter- 
 posed between the eye and external objects, place the exercise of vision under the con- 
 trol of the will. 
 
 The Muscles of the Eye, and the Levator Palpebrce Superioris. 
 
 The muscles of the eye are six in number, and are distinguished into the straight and 
 the oblique. There are four straight and two oblique muscles. With these we shall 
 also describe the levator palpebrae superioris. 
 
 Dissection. — Remove the roof of the orbit by two cuts with the saw, meeting each oth- 
 er at an acute angle opposite the optic foramen ; be careful that the inner cut does not 
 injure the cartilaginous pulley of the superior oblique muscle. Dissect the origins of 
 these several muscles from the deepest part of the orbit with the greatest care. They 
 are arranged completely round the optic nerve (o, figs. 237, 238) and the motor oculi 
 nerves. Those which arise above the optic nerve are attached to the dura mater and 
 periosteum, but not to the bone ; but those which arise below the nerve adhere more 
 closely to the bone. The inferior or small oblique muscle is the only one which does 
 not arise from the bottom of the orbital cavity. 
 
 The Levator Palpehra Superioris. 
 
 The levator paipebra superioris (a, figs. 237, 238), much thinner and narrower than the 
 rectus superior, which is subjacent to it, arises from ^^ 237. 
 
 the bottom of the orbit, at the upper part of the mar- 
 gin of the optic foramen, or, rather, from the fibrous 
 sheath given oflT from the dura mater around the op- 
 tic nerve. It arises by short and radiated tendinous 
 fibres, to which the fleshy fibres succeed, in the form 
 of a thin, flat muscle, that passes outward in a line 
 parallel with the axis of the orbit, is reflected upon 
 the globe of the eye, and ends in an aponeirrotic ex- 
 pansion, which is inserted in the upper border of the 
 tarsal cartilage of the upper eyelid 
 
 Relations. — It is covered by the periosteum of the 
 roof of the orbit, it is covered obliquely at its origin 
 by the ophthalmic nerve, and it covers the superior rectus muscle. 
 
 Action. — ^This muscle raises the upper eyelid, and draws it backward, so that the up- 
 per border of the eyelid is concealed under the orbital arch. 
 
 The Rectus Superior, or Levator Oculi. 
 
 The superior rectus (5) has two very distinct origins. The first resembles that of the 
 levator palpebrae superioris in being from the upper part of the fibrous sheath of the optic 
 nerve, but it is on a lower plane than that muscle ; the second is from the inner margin 
 of the sphenoidal fissure, i. e., between that fissure and the optic foramen. The latter 
 origin, which is continuous with those of the external rectus, appears to take place from 
 the sheath furnished by the dura mater to the third cranial or motor oculi nerve. 
 
 The fleshy fibres arising from this radiated tendon form a flat bundle, which passes for- 
 ward and outward in the direction of the axis of the orbit, and is reflected upon the eye- 
 ball, where it becomes converted into a broad and thin aponeurosis, and is inserted into 
 the sclerotic coat, at a short distance from the cornea. 
 
 This muscle, like all the other recti, is in relation with the periosteum of the orbit, 
 
 4N 
 
 «iv 
 
650 NEUROLOGY. 
 
 from which it is separated towards the inner side by the levator palpebrae superioris ; it 
 covers the optic nerve and the eyeball. 
 
 The Rectus Inferior, or Depressor Oculi. 
 The inferior rectus (c) arises, together with the internal and external recti, by a common 
 tendon, called the tendon or ligament of Zinn, which is attached to the lower half of the 
 optic foramen, and more particularly to a depression which is seen to the inner side of 
 the sphenoidal fissure. Almost immediately after its commencement this tendon divides 
 into three branches, from the middle one of which the inferior rectus muscle arises, and 
 then passing horizontally forward and outward, is reflected upon the globe of the eye, 
 and terminates in a similar manner to the preceding muscle. 
 
 The Rectus Internus, or Adductor Oculi. 
 The internal rectus {d) has two very distinct origins : one from the tendon of Zinn, the 
 other from the inner side of the fibrous sheath of the optic nerve ; the latter origin is 
 contmuous with those of the superior rectus. From these points it passes forward along 
 the internal wall of the orbit, is reflected upon the globe of the eye, and terminates like 
 the preceding muscles. 
 
 The Rectus Externus, or Abductor Oculi. 
 The external rectus (e) also has a double origin : one inferior, derived from the liga- 
 ment of Zinn ; the other superior, from the fibrous sheath of the sixth cranial or abdu- 
 cens oculi nerve, and continuous with the external origin of the superior rectus. A 
 fibrous arch, under which certain veins pass, unites these two origins, and also serves 
 as a point of attachment to the muscular fibres. From these points the muscle passes 
 obhquely forward and outward along the external wall of the orbit, is reflected upon the 
 eyebaU, and terminates like the other recti muscles. 
 
 General Description and Action of the Recti Muscles. 
 
 The four straight muscles of the eye arise from the bottom of the orbit, and terminate 
 upon the eyeball, a few lines from the cornea. 
 
 They all have the same form, viz., that of a long isosceles triangle, having its base 
 turned forward and its apex backward. Their relations are also similar : tlius, they cor- 
 respond, on the one hand, to the periosteum of the orbit, and on the other to the optic 
 nerve and the globe of the eye, from which they are separated by some fat and vessels. 
 
 In consequence of their being inserted in front of the transverse diameter of the eye, 
 they are all reflected upon the eyeball ; this fact is rendered much more evident when 
 the eye is drawn in an opposite direction to that in which the particular muscle under 
 examination would act. Their tendons are surrounded with a whitish, and, as it were., 
 elastic cellular tissue, by which the movements of these muscles are facilitated.* 
 
 The recti differ from each other, both in length and thickness. Thus, the internal 
 rectus is the shortest and thickest, the external rectus is the longest, and the superior 
 rectus is the smallest. 
 
 Action. — If these muscles were not reflected upon the globe of the eye, their action 
 would be simply to draw it forcibly backward towards the bottom of the orbit ; but, in 
 consequence of this reflection, they can give it a rotatory motion. Thus, the superior 
 and inferior recti rotate the eyeball upon its transverse axis, while the internal and ex- 
 ternal recti rotate it upon its vertical axis. After either of these effects is produced, the 
 eye is then drawn backward. The direct movement backward is produced by the si- 
 multaneous contraction of the four muscles. 
 
 When any two adjacent recti act together, the eye is moved in the diagonal of the two 
 forces exerted by those muscles ; and hence the eye, and therefore the pupil, can pass 
 over all the radii of the circle represented by the base of the orbit ; this arrangement is 
 not only highly favourable to the exploratory power of the eye, but also assists in placing 
 the function of vision under the control of the will, since it enables us to turn away the 
 eyes from any offensive object. The straight muscles of the eye, as well as the oblique 
 muscles, also aid in expressing the passions ; and hence the following names have been 
 given to them by the ancients. The superior rectus is called superbus (mirator, Haller) ; 
 the inferior rectus, humilis ; the external rectus, indignatorius ; the internal rectus, amor 
 torius seu bibitorius. 
 
 Lastly, it has been supposed that the muscles of the eye, by compressing that organ, 
 can alter the distance between the retina and the crystalline lens ; and a theory to ex- 
 plain the power we possess of adapting the eye for distinct vision at different distances 
 has even been constructed on the supposed possibility of this compression. 
 
 The necessarily simultaneous and co-ordinate action sometimes of the same muscle, 
 and sometimes of different muscles in the two eyes, is a remarkable physiological fact. 
 Thus, the contraction of the superior rectus of the right eye is of necessity accompanied 
 by contraction of the corresponding muscle of the left eye ; while the contraction of the 
 external rectus of one eye is accompanied by contraction of the internal rectus of the 
 
 * [Small synovial bursa have been described as existing between tbese tendons and the globe of the eye.] 
 
THE OBLiaUE MUSCLES OF THE EYE. 
 
 651 
 
 other eye, and vice versa : the will can neither prevent nor disarrange these co-ordinate 
 contractions. However, even without much practice, it is possible to overcome them, 
 so far as to squint by endeavouring to look at the nose. 
 
 It is not uninteresting to remark, that the sixth cranial nerve, or the abducens oculi, 
 is destined exclusively for the external rectus muscle ; and that the third cranial nerve, 
 or motor oculi, supplies the three other recti, the levator palpebrae superioris, and the 
 obliquus minor. No other muscles in the body receive such large nerves in proportion 
 to their size as those of the eye. 
 
 Tke Oblique Muscles of the Eye. 
 
 These are two in number, the superior or great oblique, and the inferior or lesser oblique. 
 The Obliquus Superior. 
 
 Tke superior or great oblique muscle of the eye (/, fig. 238) is a long filiform muscle, 
 which is reflected over a pulley or trochlea, and hence has been jv^. 238. 
 
 termed the trocklearis muscle ; it arises from the fibrous sheath of the 
 optic nerve, between the superior and internal recti, in the same 
 manner and upon the same plane as those muscles ; from this point 
 it passes forward along the i^ngle formed by the junction of the roof 
 with the inner wall of the orbi, and forms a rounded muscular fas- 
 ciculus, which ends in a rounded tendon near the cartilaginous pulley 
 intended for its reception ; the tendon passes through this pulley, is i| 
 reflected upon itself at an acute angle, so as to be directed down- " 
 ward, outward, and somewhat backward ; gets beneath the superior 
 rectus, where it spreads out, and is then inserted into the sclerotic 
 coat on a level with the longest transverse diameter of the eyebsil], 
 and, consequently, farther back than the insertion of the recti. The 
 superior oblique is the longest muscle of the eye 
 
 The trochlea, or pulley of the superior oblique, is a small cartilage, 
 which forms five sixths of a short cylinder or ring ; the edges of this 
 imperfect cylinder are attached to the slight bony ridges which 
 bound a depression upon the superior wall of the orbit. Its attach- 
 ment is effected by means of loose ligamentous fibres, so that the 
 pulley itself has a certain degree of mobility. The gliding of the 
 parts is facilitated by a synovial membrane, which is reflected from the tendon upon the 
 pulley, and is prolonged in front of and behind the latter. Beyond the pulley, a whitish 
 filamentous tissue takes the place of the synovial membrane. 
 
 The relations of the superior oblique are similar to those of the superior rectus. 
 
 Action. — Like aU reflected muscles, the superior oblique must act from the point of its 
 reflection. It follows, therefore, that this muscle rotates the eye upon itself from with- 
 out inward, that is, around its antero-posterior axis. From the oblique direction of its 
 t^don from before backward, after it is reflected, it can draw the eye forward, and 
 tends to bring it out beyond the orbit. This muscle is believed to assist in the expres- 
 sion of the tender passions (jnusculus patheticus). The fourth cranial nerve, also called 
 the trochlear or pathetic nerve, is destined exclusively for this muscle. 
 
 The Obliquus Inferior. 
 
 The inferior or lesser oblique (g, fig. 237, 238) is the shortest muscle of the eye, and 
 the only one which does not arise from the bottom of the orbit ; it arises from the inner 
 and anterior part of the floor of that cavity, and, therefore, from the orbital surface of the 
 superior maxillary bone, immediately behind the margin of the orbit, and often even 
 from the lachrjnnal sac. From this origin it passes backward, in the form of a flat bun- 
 dle, which turns round the lower surface of the globe of the eye, situated at first between 
 the eyeball and the inferior rectus, then between it and the external rectus, and at 
 length ends in an aponeurotic expansion, which is blended with the sclerotic, near the 
 outer border of the superior rectus. 
 
 Its insertion into the sclerotic is farther back than that of the superior oblique, and, 
 therefore, much farther back than those of the recti. 
 
 Action. — It rotates the eye in the opposite direction to the superior oblique. Its turn- 
 ing round the lower surface of the eyeball renders its action extremely effective. From 
 its oblique course from before backward, it can draw the eye slightly forward. 
 
 The Lachrymal Passages. 
 
 The term lachrymal passages includes both the apparatus for secreting and that for con- 
 veying away the tears, consisting of a secreting organ, named the lachrymal gland ; of 
 excretory ducts, which pour out the tears upon the conjunctiva ; and of a second set of 
 ducts, intended to absorb the tears and convey them into the nasal fossae, comprising 
 the puncta lachrymalia, the lachrymal canals, the lachrymal sac, and the nasal ducts. Such 
 is the order in which we shall describe this apparatus. 
 
6S2 NEUROLOGY. 
 
 The Lachrymal Gland. . , ^ 
 
 The lachrymal gland (glandula innominata of the ancients) consists of two very distinct 
 parts : an orbital portion, situated in the fossa on the roof of the orbit ; and a. palpebral por- 
 tion, which is enclosed in the substance of the upper eyehd. 
 
 The first or orbital portion (I, fig. 207), the only part generally described, is of an irreg- 
 ular semi-ovoid form, having its long diameter placed transversely. It varies in size in 
 different subjects, but is generally about as large as a filbert.* Its upper surface is con- 
 vex, and corresponds to the fossa in the frontal bone, to which it adheres, especially in 
 front, by very distinct fibrous bands : its interior surface is concave, and is in relation 
 with the external rectus, and with a small part of the superior rectus. Its anterior bor- 
 der corresponds to the orbital arch, or, rather, to the fibrous membrane of the eyelid, im- 
 mediately behind which it is situated ; hence it maybe exposed by an incision along this 
 arch. By its posterior edge it receives its vessels and nerves. 
 
 The second or palpebral portion, though continuous with the first, is separated from it 
 by several fibrous bands. It forms a thin granular layer, which is covered and concealed 
 by a very dense lamina of fibrous tissue that appears to be prolonged into its interior. 
 This palpebral portion occupies the outer portion of the upper eyelid, and extends almost 
 as far as the upper border of the tarsal cartilage. 
 
 The Excretory Ducts of the Lachrymal Gland. — Before the discovery of these excretory 
 ducts, it was only by inference that the so-called glandula in7iominata was regarded as 
 the secreting organ of the tears. In 1661 Steno discovered these ducts in the sheep, m 
 which animal they are large enough to admit bristles. He described thirteen or fourteen 
 ducts. The difficulty of detecting these ducts in the human subject is sufficiently proved 
 by the fact that neither Morgagni, Zinn, nor Haller could ever find them ; the second 
 Monro, however, succeeded in filling them with mercury, and described them accurate- 
 ly. They are from ten to twelve in number ; they run parallel to each other beneath the 
 palpebral conjunctiva, and open upon the inner surface of the eyelid by a corresponding 
 number of orifices {d,fig. 235), placed very regularly about a line from the tarsal cartilage, 
 along its outer half. MM. Chaussier and Ribes have succeeded in filling them with mer- 
 cury, by injecting them from the gland towards the eyelids. Having sought in vain, 
 both with the naked eye and with a lens, for the orifices of the excretory ducts of the 
 lachrymal gland in the human subject, I thought of dipping the eye and eyelids in a so- 
 lution of carmine or slightly-diluted ink ; and I then saw distinctly a dozen openings ar- 
 ranged in a line along the point of reflection of the palpebral conjunctiva upon the eye- 
 ball, and occupying the outer half of the eyelid, t 
 
 The Lachrymal Puncta and Canals. 
 The puncta lachrymalia {a, fig. 239), two in number, one for each eyelid, are those small 
 Fig 239. orifices or foramina which are visible to the naked eye in the centre 
 
 of the lachrjonal papillae : they are perfectly circular, are always 
 open, and are directed backward, the upper one being turned do*n- 
 ward, and the lower one upward. These openings, which are ia^t 
 apart from each other by the caruncula lachrymalis, are the cjq)il- 
 lary orifices of two small canals, called the lachrymal canals. 
 
 The lachrymal canals {I I) are small tubes, extending from the 
 puncta lachrymalia to the lachrymal sac. They are two in num- 
 ber, a superior and an inferior, each being somewhat larger than 
 the corresponding lachrymal punctum. Their angular course is very remarkable. They 
 pass at first vertically, the superior duct upward, and the inferior duct downward, and 
 after a short course they bend abruptly at right angles, run inward, and open by separate 
 orifices, never together, into the anterior and external part of the lachrymal sac. The 
 direction of the second portion of each of the lachrymal canals varies according as the 
 eyelids are closed or open : the duct of the lower eyelid is directed somewhat obliquely 
 upward, that of the upper eyelid downward, even when the lids are completely closed ; 
 but they are both very oblique when the eyelids are separated ; and as this separation 
 is principally due to the elevation of the upper eyelid, it follows that the obliquity of the 
 upper lachrjrmal canal must be very well marked. 
 
 The coats of the lachrymal canals are dense and elastic, so that they do not collapse 
 when empty, and must, therefore, act as capillary tubes. We do not find any sphincter, 
 either at their palpebral or their nasal orifice ; they appear to be formed in the sub- 
 stance of the free margin of each eyelid ; they are lined by a prolongation of the con- 
 junctiva, and are covered by the fibres of the orbicularis palpebrarum muscle. Behind 
 them are found some muscular fibres, forming a dependance of a small fasciculus, called 
 the muscle of Horner, or the lachrymal muscle, which was believed by that anatomist to 
 serve in drawing the lachrymal ducts inward. 
 
 * [It has all the anatomical characters of a compound gland.] 
 
 t T find in Haller that it was in a human eye which had been macerated for some time in water tinged with 
 blood, that Monro (Secundus) discovered these orifices. After they have been discovered, it is easy to intro- 
 duce the end of the rasrcurial injecting pipe into them. 
 
THE LACHRYMAL PASSAGES. 658 
 
 The Muscle of Homer. 
 
 Dissection. — ^Turn the eyelids inward, and carefully remove a fibrous layer which cov- 
 ers this muscle upon the lachrymal sac. 
 
 This small muscle arises from the vertical ridge of the os unguis, which forms the pos- 
 terior border of the lachrymal groove ; from this point it passes transversely outward 
 along the posterior tendon of the orbicularis palpebrarum, and divides into two tongues, 
 a superior and an inferior, which correspond to the lachrymal canals, and terminate at 
 the respective lachrymal puncta. 
 
 I regard these fibres as a dependance of the orbicularis palpebrarum. 
 
 The Lachrymal Sac and Nasal Duct, or Lachrymo-nasal Canal. 
 
 The lachrymal sac and nasal duct constitute a single canal, which extends from the up- 
 per part of the lachrymal groove to the inferior meatus of the corresponding nasal fossa. 
 
 The lachrymal sac (wi), that portion of the lachrymo-nasal canal which occupies the 
 lachrymal groove, represents the half of a cylinder terminating above in a cul-de-sac. It 
 is buried, so to speak, in the substance of the inner wall of the orbit, immediately be- 
 hind the margin of that cavity, and is in relation with the inner angle of the eyelids, the 
 caruncula lachrymalis, the adipose tissue of the orbit, and the tendon of the orbicularis 
 muscle. The last-named relation is one of the most important points in the anatomy of 
 the lachrymal sac. If a circular incision be made through the eyelids from their outer 
 aigle along their adherent borders, and the lids be then turned inward, by then careful- 
 ly dissecting the tendon of the orbicularis, it will be found that that tendon divides into 
 three branches ; that the anterior branch, called the straight tendon, is inserted in front 
 of the ascending process of the superior maxillary bone ; that the posterior branch, which 
 is of equal size with the anterior, is inserted into the ridge upon the os unguis, behind 
 the lachrymal groove ; that the middle branch ascends to be attached to the upper part 
 of the lachrymal groove ; and, lastly, that the lower part of the tendon gives off a fibrous 
 expansion, which forms the outer side of the lachrymal sac, and which may be regard- 
 ed as a fourth tendinous expansion. The muscle of Homer lies upon the posterior of 
 these tendons, and must be regarded as a portion of the orbicularis itself 
 
 The tendon of the orbicularis palpebrarum corresponds to the upper part of the lachry- 
 mal sac, only its cul-de-sac projecting above the tendon. The greatest part of the sac 
 is, therefore, situated below it. 
 
 The internal surface of the lachrymal sac presents the ordinary appearance of all ca- 
 nals lined by mucous membrane : a considerable quantity of mucus is often found in it. 
 At the anterior part of its external wall, and at about an equal distance from the top and 
 bottom, are the two orifices of the lachrymal canals ; above, is the narrow cul-de-sac, in 
 
 hich it terminates in that direction ; and below, it becomes continuous with the nasal 
 duct : in this place there is rather frequently found a semilunar, sometimes even a cir- 
 cular valve ; this is the kind of diaphragm spoken of by Zinn, but the existence of which 
 w^denied by Morgagni. Haller says that he only met with it once. 
 
 lachrymal sac consists of a partly bony and partly fibrous canal, lined by a mu- 
 embrane. The bony portion of this canal is formed by the groove upon the as- 
 ing process of the superior maxillary bone, and upon the os unguis ; the last-men- 
 led bone, which is thin and pierced with foramina, may be easily perforated ; and 
 hence the facility of making an artificial passage for the tears. The lachrymal sac is 
 opposite to the middle meatus of the corresponding nasal fossa. 
 
 The fibrous portion forms the external flattened wall of this canal ; it is very strong 
 and unyielding, unless to long-continued extension. 
 
 The slight muscular layer, described as the muscle of Horner, may be regarded as be- 
 longing to the lachrymal sac : this muscle is itself covered by a layer of fibrous tissue. 
 
 The lining mucous membrane of the lachrymal sac is reddish, and, as it were, pulpy, 
 and closely resembles the pituitary membrane ;* from its close attachment to the peri- 
 osteum of the walls of the canal, it might be called afibro-mucous membrane. 
 
 The nasal duct (n), which may be said to be formed in the outer wall of the corre- 
 sponding nasal fossa, extends from the lachrjTnal sac to the anterior part of the inferior 
 meatus of the nose. It is of a cylindrical shape, slightly flattened on the sides, and rath- 
 er narrower at the middle than at its extremities. It is directed vertically, but forms a 
 slight curve, having its concavity turned forward and outward. It may be also readily 
 conceived that the relative breadth of the root of the nose must affect the direction of 
 this canal. 
 
 It corresponds, on the inner side, to the middle meatus of the nose, and the inferior tur- 
 binated bone ; on the outer side, to the maxillary sinus, from which it is separated by a 
 very thin lamina of bone. This latter relation has doubtless led one anatomist to state 
 that the nasal canal opens both into the maxiUary sinus and the nasal fossa. 
 
 The nasal canal consists of a bony canal lined by a fibro-mucous membrane ; the bony 
 canal is complete, and is formed by the superior maxillary bone, the os unguis, and the 
 inferior turbinated bone. It is very strong in the part formed by the superior maxillary 
 
 * See note, p. 654. 
 
654 NEUROLOGY. 
 
 bone, excepting opposite to the sinus in that bone, but it is very thin and fragile where 
 it is formed by the os unguis and inferior turbinated bone. Its lining membrane is of a 
 fibro-mucous structure ; it adheres very slightly to the walls of the canal, and is contin- 
 uous, on the one hand, with the mucous membrane of the lachrymal sac, and, on the 
 other, with the pituitary membrane.* This lining membrane is often prolonged for sev- 
 eral lines beyond the nasal duct, so as to form a valvular fold (o). Where this fold ex- 
 ists, the inferior orifice of the nasal duct (see r,fig. 233) is always closed, and, there- 
 fore, difficult to be detected, even when the inferior turbinated bone has been taken 
 away or displaced, so that, in order to discover it, it becomes necessary to introduce a 
 probe through the lachrymal passages from above. In catheterism of thelift|J duct 
 from below upward, according to the method practised by Laforest, this fold ^Btocous 
 membrane must of necessity be torn. ^fe 
 
 It has been stated by some authors, that the lower orifice of the nasal duct isp^e- 
 ded by an ampulla, or infundibuliform dilatation. I have met with this disposition, but 
 regarded it as morbid. I am convinced that a great many lachrymal tumours depend 
 upon contraction or obliteration of the lower orifice of this canal. « 
 
 The Globe of the Eye. 
 The globe of the eye {v,fig. 240) is situated in the fore part of the orbital cavity ; it is retain- 
 Fig. 240. ed in this situation by the optic nerve (o), the straight 
 
 and oblique muscles {beg), the vessels, the conjunctifa 
 (d), and the eyelids ; these parts, however, do not con- 
 fine it in a fixed position, but allow it great mobility. In 
 fact, the eye can be rotated around all its axes, and 
 can even be drawn forward and backward (see Mus- 
 cles of the Eye). The eyes are small in comparison to 
 the orbital cavities ; and they present some slight dif- 
 ferences as to size in different persons, which have 
 not yet been properly estimated. The common terms. 
 large and small eyes apply less to the eyeball than to 
 the opening between the eyelids. The eye is propor- 
 tionally larger in the foetus and new-born infant than'in the adult and aged. 
 
 Inform, the globe of the eye resembles a regular spheroid, to- the front of which r? at- 
 tached a segment of a smaller sphere {see fig. 241) : by this arrangement, the anjfero- 
 posterior diameter of the organ is increased to the length of eleven lines, whil^it^l^h- 
 er diameters are only ten lines. It is said that the form of the eyeball can ' 
 by the contraction of its muscles, but, in consequence of the great tension of tj 
 the alteration produced is so slight tj^at it scarcely deserves to be mentioned. 
 
 The general relations of the eyeball are the following : in front, it is covere 
 conjunctiva and the eyelids, which defend it from light and from dust, rather 
 external violence. It results, also, from the obliquity of the margin of the orbit,' 
 the outer side, the eye projects considerably beyond the bones. In every other pi 
 its surface the eye rests upon an elastic cushion of fat (//), which separates it' 
 the muscles and nerves, fills up all intervals, and facilitates the movements of the or^ 
 The absorption of this fat in emaciated individuals causes the depression of the eyej 
 the orbital cavity. A membranous cellular tissue, or, rather, a rudimentary sync 
 membrane, exists between the eye and this fat. ., 
 
 Structure. — Like all the other organs of the senses, the eye consists essentially of a 
 membrane provided with a special nerve, and of a particular apparatus, placed in relation 
 with the external agent by which the organ is to be acted upon. In the organ of vision, 
 the sentient membrane is the retina, which is the immediate seat of the sense of sight ; 
 the other parts of the eyeball form nothing more than a very comphcated dioptric instru- 
 ment, a dark chamber, in which the rays of light are refracted, and concentrated so as 
 to form a vivid image, and which is, moreover, provided with a movable diaphragm to 
 regulate the number of rays to be admitted. 
 
 In an anatomical point of view, the eye is said to consist of certain membranes and 
 humours. The membranes, counting from without inward, are the sclerotic coat and cor- 
 nea, the choroid coat and iris, and the retina. The humours are, the vitreous body and its 
 hyaloid membrane, the crystalline lens and its capsule, and the aqueous humour. 
 
 The Sclerotic. 
 
 Dissection. — Clean the globe of the eye, leaving the attachments of the muscles to the 
 sclerotic coat ; with a pair of strong scissors divide this coat circularly into an anterior 
 and posterior portion, taking care to avoid the choroid coat ; turn the one portion for- 
 ward and the other backward. It is easier to make this section, without injuring the 
 choroid, upon a slightly flaccid eye than upon one which is perfectly fresh. 
 
 The sclerotic {aK%T]pdg, hard), or the opaque cornea {b,fig. 241), is the outermost of the 
 
 * [The epithelium of the mucous membrane of all the lachrymal passages is columnar, and, according to 
 Henle, is provided with cilia, although Perkinj6 and Valentin failed to discover them in these situations.] 
 
THE CORNEA. 655 
 
 coats of the eye, and forms, as it were, the shell of that organ ; it is of a pearly- white 
 colour, and very stroag,;. it is perforated behind to give passage to the optic nerve (o), 
 and presents a circular opening in front (from a to a), into which the cornea is fitted. 
 
 Its external surface forms the outer surface of the eyeball, and therefore has the same 
 relations. Thus, it is covered in front by the conjunctiva, which adheres to it by means 
 of very loose cellular tissue, that is liable to infiltration. The straight and oblique mus- 
 cles of the eye are implanted into it. An imperfect or rudimentary synovial capsule 
 separates it from the cushion of fat, and gives it a smooth aspect. 
 
 Its internal surface has a dull, rough appearance, very different from that of its exter- 
 nal surface : it is, moreover, of a deep-brown colour, from the choroid pigment ; it cor- 
 responds to the choroid coat (c), and is united to it by a very delicate cellular tissue, and 
 by the ciliary vessels.* The ciliary nerves run from behind forward between the scle- 
 rotic and the choroid, occupying slight grooves upon the internal surface of the former. 
 Both the ciliary vessels and nerves perforate the sclerotic coat very obliquely. 
 
 Structure. — ^The sclerotic is one of the thickest and strongest fibrous membranes in 
 the body^ it is not of uniform thickness throughout ; it is thickest behind, at the entrance 
 of the optic nerve, and thinnest in front, near the cornea. Like all the fibrous mem- 
 branes, it is unyielding ; and on this depends the firmness and tense condition of the 
 globe of the eye : it is also the cause of the intense pain produced by inflammation of 
 the interior of the eye and by certain cases of hydrophthalmia. 
 
 The older anatomists considered the sclerotic to be composed of two layers, the inner 
 of which was, according to Zinn, a prolongation of the pia mater, and, according to 
 Meckel, of the arachnoid. But, independently of the fact that the division of the sclerot- 
 ic into two layers is purely artificial, it may be stated that neither the pia mater nor the 
 arachnoid is prolonged upon the optic nerve. Lastly, the sclerotic has been regarded as 
 a continuation of the dura mater, through the medium of the neurilemma of the optic 
 nerve ; and this view is supported by dissection, which shows clearly that the sheath 
 furnished by the dura mater to the optic nerve is prolonged upon the sclerotic. It has, 
 moreover, been stated, but incorrectly, that the anterior part of the sclerotic has an ad- 
 ditional layer, formed by the union of the tendons of the recti muscles. 
 
 The sclerotic is composed of fibrous bundles which interlace in all directions. 
 
 Its use is especially to protect the globe of the eye, of which it forms the covering and 
 determines the shape. 
 
 .;- The Cornea. 
 
 ^' 
 
 The transparent cornea {a a, fig. 241) completes the external shell of the eye in front : 
 in reference to the sclerotic coat, it represents a segment of a smaller sphere superadded 
 to a larger sphere ; its circumference is circular, or, rather, slightly elliptical, for its 
 transverse diameter is half a line longer than its vertical diameter. 
 
 Its anterior surface is convex, and projects forward beyond the sclerotic ; it is covered 
 by^he conjunctiva, which adheres to it so closely, that the existence of that membrane 
 v^^fm it has Been denied by some anatomists.! 
 
 ■"Ij^o great a convexity of the cornea, by increasing the refracting power of the eye, 
 ^jgftasions myopia, or short-sightedness. 
 
 ■ its posterior surface is concave, and forms the anterior wall of the anterior chamber 
 of the eye. A thin membrane (m) covers this surface, and is called the membrane of the 
 aqueous humour. 
 
 The circumference of the cornea, which is fitted into the opening in the front of the scle- 
 rotic, is cut obliquely, so that its external surface is smaller than its internal surface ; the 
 oblique edge of the sclerotic, to which it corresponds, is sloped in the opposite direction. 
 
 The cornea and sclerotic adhere so closely that they were for a long time regarded as 
 forming but one coat ; but, independently of their difference in appearance and texture, 
 they may be separated by boiling or by long-continued maceration. 
 
 Structure. — The cornea is thicker than the sclerotic : it may be separated into a great 
 number of lamellas, united by very thin layers of cellular tissue ; but this separation is 
 purely artificial, so that the number of lamellae is indefinite. The thinnest layer of fluid 
 interposed between the lamella; is sufficient to impair the transparency of the cornea; 
 maceration, accordingly, gives it a milky appearance. The opacity of the cornea, which 
 occurs in some cases of ophthalmia, depends upon the infiltration between the lamellae 
 of a certain quantity of fluid, after the absorption of which the cornea recovers its ori- 
 ginal transparency. 
 
 No vessels can be shown in the cornea, even by the aid of the finest injections of the 
 arteries and veins of the eye : its superfi^cial layer, which is continuous with the con- 
 junctiva, contains a network of lymphatics communicating with those of the conjunc- 
 tiva, and capable of being demonstrated by puncturing any part of the superficial layer of 
 
 * See note, p. 656. 
 
 t A careful dissection, especially after prolonged maceration, shows the continuity of the most superficial 
 layer of the cornea with the conjunctiva. A malformation sometimes occurs iu which oni^ part of the cornea 
 is covered by a prolongation of the conjunctiva. 
 
656 
 
 NEUROLOGY. 
 
 the cornea. It is useless to introduce the tube deeper, for the lymphatic network is en- 
 tirely superficial. 
 
 Uses. — The transparent cornea is the first medium through which the rays of light 
 have to pass ; in consequence of its density and its convexity, it refracts the rays of light, 
 and causes them to converge. The density of the cornea is the same in different per- 
 sons ; but its convexity is subject to variations, upon which depend, in a great measure, 
 the states of myopia (short sight), presbyopia (long sight), and natural vision. 
 
 The Choroid Coat, and the Ciliary Circle and Processes. 
 
 The choroid (indicated by the thick black hue, c,Jlg. 241), so called from its extreme 
 vascularity,* is the second membrane of the eye, proceeding from without inward ; it 
 is a vascular membrane, covered with a thick layer of pigment : it exactly lines the 
 sclerotic, and terminates, like it, at the circumference of the cornea. 
 
 Its external surface (c, jigs. 242, 244) adheres to the schlerotic by means of the ciliary 
 vessels and nerves, and by a thin and very delicate cellular tissue, which is easUy lacer- 
 ated, and when raised appears like a spider's web.+ This surface, when magnified, has 
 a fiocculent appearance. 
 
 Its internal surface is in relation with, but does not adhere to, the retina (r, fig. 241), by 
 which it is lined nearly throughout its whole extent. 
 
 Both surfaces of the choroid are covered with a pigment, which resembles the pigment 
 of the skin of negroes ; this pigment is much more abundant on the internal than on 
 the external surface, and less so behind than in front, where it forms a thick layer, in 
 the form of a zone surrounding the corona ciliaris. 
 
 Upon both surfaces are found innumerable longitudinal and contorted lines, which 
 correspond to the vessels of the choroid. 
 
 In a great number of animals, in the ox, for example, the pigment on the interned sur- 
 face of the choroid at the back of the eye is replaced by a brilliant metallic-looking sub- 
 stance called the tapetum. When deprived of its pigment, the internal surface of the 
 choroid presents a smooth aspect, and is not fiocculent like the external surface. It is 
 of a grayish- white colour, and anteriorly, where it is covered by a thick layer of pigment, 
 it becomes white and shining when the pigment is removed. 
 
 Behind, the choroid is pierced by a circular opening for the passage of the optic nerve ; 
 in front, it terminates in the ciliary circle and ciliary processes, which must be regarded as 
 appendages to it. 
 
 T'he Ciliary Circle. — The ciliary circle, ring, or ligament («, fig, 241 ; b, figs. 242, 
 fin. ail, 244), IS a circular zone, from a line to a 
 
 J j_ line and a half in breadth, of a grayish col- 
 
 our, and soft consistence, which bounds 
 the choroid coat (c c) in front. It is of con- 
 siderable thickness. Its external surface 
 corresponds to the sclerotic, to which it is 
 slightly adherent. Its internal surface Qpr- 
 responds to the ciliary processes (e, fig. 
 241) ; by its outer or larger border, which 
 is distinguished from the choroid by a slight 
 ridge, it receives the ciliary nerves (a a, 
 fig. 242), which bifurcate, and appear to 
 anastomose with each other before they 
 enter the substance of the ciliary circle : 
 by its lesser or inner border, wliich corre- 
 sponds to the iris (i), it adheres intimately 
 to the circumference of the cornea, exactly where that membrane is continuous with the 
 sclerotic (at a a, fig. 241). The older anatomists called this structure the ciliary liga- 
 merU. From the great number of the nerves which enter the ciliary circle, from its gray- 
 ish colour, and its pulpy aspect, modern anatomists have regarded it as a nervous gan- 
 glion (annulus gangliformis, or annular ganglion, Sammering). 
 
 Fig. 242. Some anatomists describe, under the name of the ciliary canal, 
 
 or the canal of Fontana, a very small and extremely narrow cir- 
 cular space (u V, fig. 241), which is formed between the ciliary 
 circle, the cornea, and the sclerotic. This space can be filled 
 with injection, and it is not certain that it is not the cavity of a 
 bloodvessel. 
 
 The Ciliary Processes and the Ciliary Body. — If the back part 
 
 of the sclerotic, choroid, and retina be cut away, or even if the 
 
 fc globe of the eye be merely divided into an anterior and posterior 
 
 * Choroid is synonymous with vascular. 
 
 t [A serous cavity is said by some to exist betvreen the sclerotic and choroid ; 
 the lining membrane of this supposed cavity is named the arachnoid membrane 
 of the eve.] 
 
THE IRIS. ^7 
 
 half by a circular incision, on looking into the anterior half a perfectly regular radiated 
 disc {d, Jig. 241 ; a b, fig. 243) will be seen around the crystalline lens. This disc, which 
 has been very correctly compared to a radiated flower, is called the ciliary body, or cormia 
 ciliaris ; each of the rays is called a ciliary process or ray (rayon sous-irien, Chaussier). 
 If, after a correct idea of the arrangement of this radiated disc has been obtained, the 
 choroid coat be separated from the humours of the eye, it will be found that there are two 
 perfectly distinct discs : one of these remains attached to the choroid coat, and constitutes 
 the ciliary disc or ciliary body of the choroid (a b, fig. 243) ; the other remains attached to the 
 vitreous body and to the crystalline lens, and is the ciliary zone of pig, 243. 
 
 Zinn, which may be termed, after M. Ribes, the ciliary processes 
 of the vitreous body (a b,fig. 248). We shall now describe the cil- 
 iary processes of the choroid coat only, leaving the ciliary pro- 
 cesses of the vitreous body to be described together with that part 
 of the eye. 
 
 The ciliary processes of the choroid coat, so well described by 
 Zinn, who enumerates sixty of them, are regarded as so many 
 folds of the internal layer of the choroid. They may be divided 
 
 into great and small, the latter occupying the intervals between 
 
 the former. They all increase in size (from b to a, fig. 243) as Pcterior or imemJ view. 
 they approach the outer border of the iris, behind which they are prolonged without adhe- 
 ring to it, and are then bent forward upon themselves, to be attached to that border. These 
 ciliary processes, the sides of which are turned towards each other, have, therefore, a 
 posterior adherent or choroid portion (b), and an anterior free or iridian portion (a). The 
 free portion (c e, fi^. 241 ; a, fig. 244) floats among the humours of the eye like a fringe ; 
 ,the slightest agitation of the vessel or of the liquid in which the 
 ciliary processes are contained is immediately communicated to 
 this free portion of the corona ciliaris. 
 
 The ciliary body or disc, which is formed by the union of all the 
 ciliary processes or rays, is in relation behind with the vitreous 
 body {v in the centre, ^^. 241), and advances (e,fig. 241 ; a, fig. 
 244, in which the iris is removed) over the circumference of the 
 crystalline lens. It is not simply in contact with the vitreous body, 
 but is rather firmly adherent to it ; and we shall afterward see that 
 they are dovetailed together, that is, the ciliary processes of the 
 vitreous body are fitted into the intervals between the ciliary pro- Anterior view-im removed 
 cesses of the choroid, and vice versa. 
 
 If the thick layer of pigment with which they are covered be removed, the ciliary 
 processes of the choroid, when examined through a lens under water, have a white colour. 
 In their substance are seen irregular cells which are filled with the brown pigment, and 
 which give them a spongy, and, as it were, jagged appearance. They are evidently con- 
 tinuous with the choroid, which irxmiediately around them presents a zone of a whiter 
 colour than the rest of the inner surface of that membrane. 
 
 Structure of the Choroid Coat and its Ciliary Processes. — The structure of these parts is 
 essenticdly vascular. Fine injections thrown into the carotid artery and internal jugular 
 vein, in young subjects, fill a beautiful network of vessels in this membrane. The vor- 
 ticose arrangement {v, fig. 244) of some of these vessels is then clearly displayed ; and, 
 indeed, this is very well indicated, without the aid of an injection, by the striae already 
 described as visible upon the surfaces of the choroid. The short ciliary arteries belong 
 exclusively to the choroid coat. From a great number of experiments made by M. Ribes, 
 it would appear that injections pushed into the arteries do not enter the vdli and fringes 
 of the ciliary body, but that their vessels may be filled from the veins ; so that, accord- 
 ing to this, the structure of the free and fringed portion of the ciliary processes is alto 
 gether venous, like the cavernous or erectile tissues.* 
 
 From the different appearance of the external and internal surfaces of the choroid, 
 anatomists have regarded this coat as being composed of two layers, of which the in- 
 ternal is called the membrana Ruyschiana, after Ruysch, who has given the best descrip- 
 tion of it. According to one view, which is not altogether unsupported, the internal 
 layer alone concurs in the formation of the ciliary processes, while the external layer 
 corresponds to the ciliary ring. 
 
 The Iris. 
 
 The iris {i, figs. 242, 243), so called on account of the varied colours which it presents, 
 is a membranous vertical septum, perforated in the centre, like the diaphragm of an op- 
 tical instrument. By means of this septum (i, fig. 241), the space {p) between the cornea 
 (m) and the crystalline lens (f) is divided into two parts or chambers, an anterior and a 
 posterior. The iris is circular, and perforated in its centre by an opening which consti- 
 tutes the pupil {p, fig. 242), vulgarly, the apple of the eye, and which is surrounded by 
 the lesser or inner border of the iris ; the pupil is circular in the human subject, and oblong, 
 
 * [In successful injections, arterial as well as venous ramifications are demonstrated in the ciliary processes. 1 
 
 40 
 
658 NEUROLOGY. 
 
 either transversely or vertically, in the lower animals ; the number of luminous rays suf- 
 fered to impinge upon the retina are regulated by variations in the size of this opening. 
 We constantly find in several kinds of animals, and occasionally in the human subject, 
 small fringes attached to the lesser border of the iris, which float in the aqueous humour. 
 
 The outer or greater border of the iris is, as it were, fitted in between the ciliary liga- 
 ment, which projects beyond it slightly in front, and the ciliary processes, which encroach 
 upon it behind {see Jig. 241). The manner in which it adheres to these parts is not well 
 understood. There is a true continuity of tissue, and yet they may be separated by a 
 slight degree of force ; on this is founded the operation for artificial pupil by detaching the 
 iris. The outer border of the iris is not continuous with the circumference of the cornea. 
 
 The anterior surface of the iris {i, fig. 242), with its different shades of colour, is the 
 part which is seen through the transparent cornea ; it is plane, not convex. The inter- 
 val between it and the cornea constitutes the anterior chamber of the eye {fig. 241). 
 The form and size of this interval can be correctly estimated in a frozen eye ; it is filled 
 with the aqueous humour ; its longest diameter from before backward is about one line. 
 
 When examined with a lens, the anterior surface of the iris has a flocculent appear- 
 ance, more distinct than, but similar to, that of the external surface of the choroid. It 
 appears as if it were fissured here and there, and in the human subject presents some 
 very well-marked radiated bands. When the pupil is contracted these radiated banda 
 are straight, but during its dilatation they become flexuons. They appear to interlace, 
 and thus to become blended with each other near the pupil. It is generally admitted 
 that the membrane of the aqueous humour covers the anterior surface of the iris ; but it 
 cannot be demonstrated in that situation. The colour of this surface differs in different 
 individuals, and it has generally some relation to that of the hair ; upon these differences 
 depend the colour of the eyes, whether blue, black, gray, &c. Whatever may be the 
 colour of the iris, two shades of different intensity may be distinguished in it, and occa- 
 sion the appearance of two concentric coloured zones in this membrane ; the smaller and 
 deeper-coloured zone is situated near the pupil ; the larger and lighter-coloured one in- 
 cludes the two outer thirds of the membrane. It is not always easy to distinguish these 
 two zones. 
 
 The posterior surface {i, fig. 243) of the iris corresponds to the crystalline lens, from 
 which it is separated by an interval filled with the aqueous humour, and called the pos- 
 terior chamber of the eye {fig. 241). 
 
 The two chambers of the eye, therefore, communicate at the pupil {p). 
 
 The posterior surface of the iris is covered by a thick layer of pigment, which is con- 
 tinuous with the pigment of the choroid ; near its outer border it is also overlaid by the 
 free or iridian portion (c e) of the ciliary processes of the choroid, which can be easily 
 turned back so as to expose the entire posterior surface. It presents extremely well- 
 marked radiated bands, which can be well seen, even before the choroid pigment is re- 
 moved. 
 
 The aspect of the posterior surface of the iris differs essentially from that of the an- 
 terior surface ; it is white and smooth, and resembles in many respects the internal sur- 
 face of the choroid. Some anatomists are of opinion that the posterior surface of the 
 iris is covered by the membrane of the aqueous humour. If such be the case, it is difll- 
 cult to comprehend how that membrane is arranged with reference to the pigment. 
 
 Structure. — The iris is three or four times as thick as the choroid ; it diminishes in 
 thickness from its outer to its inner border. Its real structure is but little understood. 
 The old opinion of its muscularity, which was refuted by Weitbrecht and Demours, has 
 been revived by M. Maunoir, who admits two sets of muscular fibres, viz., radiated fibres, 
 which correspond to the external coloured ring, and circular fibres, which correspond to 
 the internal coloured ring, and form a sort of sphincter around the pupil ; but no circular 
 fibres can be distinguished around the pupil. An appearance as if such were the case, 
 is occasioned by a peculiar arrangement of the radiated fibres, which seem to bifurcate 
 opposite the internal coloured ring, to interlace with each other, and then terminate ab- 
 ruptly around the pupil ; so that the inner border of the iris, or the pupil, appears to be 
 formed by the blunt extremities of these radiated fibres. 
 
 In the ox and the sheep, the iris has two very distinct sets of fibres : an anterior and 
 circular layer, which occupies the whole of the anterior surface ; and a posterior and 
 radiated set of fibres, which converge from the outer to the inner border. The anterior 
 set of fibres does not exist in the human subject. 
 
 Another and much more plausible opinion regarding the structure of the iris is, that it 
 consists of a vascular or erectile texture.* 
 
 If we examine an oblique section of the iris under a lens, we find, indeed, that it has 
 an areolar spongy structure ; and the extreme vascularity of this part also supports the 
 same view. 
 
 * A case is related of a young man who could produce contraction of the pupils by holding his breath. 
 
 [The muscularity of the fibres of the iris i.s now established beyond a doubt ; the fibres of the iris of the pig 
 are described by Schwann as being very minute, cylindrical, and not beaded ; thev therefore resemble the 
 muscular fibres of organic life.] 
 
THE MEMBBANA PUPILLARIS, ETC. 659 
 
 Arteries of the Iris. — The arteries of the iris are principally derived from the two long 
 ciliary arteries, which bifurcate and anastomose after they have reached the ciliary liga- 
 ment, and form a vascular circle, which gives off radiated vessels that converge from the 
 outer border of the iris towards the pupil. There are also some anastomotic arches 
 near the pupil. 
 
 Veins of the Iris. — The veins of the iris are much more numerous than the arteries ; 
 they terminate in the venae comites of the long ciliary arteries, and in the vasa vorticosa. 
 
 Nerves. — The nerves of the iris, or ciliary nerves {a a, fig. 242), are very large ; as we 
 have stated, they gain the ciliary circle, and then pass through it in great numbers, to 
 enter the iris, and be distributed in its substance. Most of these nerves are given off 
 from the ophthalmic ganglion : some of them are derived directly from the nasal nerve, 
 which is a branch of the fifth cranial nerve. 
 
 The older anatomists distinguished two layers in the iris : one anterior, which they called 
 the membrane of the iris ; the other posterior, covered with pigment, which they called 
 membrana uvea. By examining an oblique section of the iris with a lens, two layers may, 
 in fact, be seen, separated by the spongy tissue of which I have spoken 
 
 The Memhrana Pupillaris. 
 
 Dissection. — By opening the eye of the foetus from behind, this vascular membrane 
 may be easily seen through the vitreous body and the crystalline lens. 
 
 In the foetus, the opening of the pupil is closed by a membane, called the membrana 
 pupillaris, which was discovered and very well described by Wachendorf, but more per- 
 fectly so by Haller and Soemmering, and recently by M. Jules Cioquet. It may be seen 
 about the third month of intra-uterine life, and generally disappears towards the seventh 
 month. When persistent, it may occasion congenital blindness. Wachendorf and 
 Soemmering have demonstrated the vessels of this membrane, which are continuous 
 with those of the iris. During the existence of the membrana pupillaris, the membrane 
 of the aqueous humour forms a shut sac. From the researches of M. Jules Cioquet con- 
 cerning the pupillary membrane, it appears that it consists of two thin layers, between 
 which the bloodvessels are arranged in loops ; that the convexities of these loops are 
 turned towards each other, but that the loops which approach each other from opposite 
 sides do not anastomose together ; that between these loops, and towards the centre of 
 the pupil, there is a small irregular portion of the membrane which is destitute of ves- 
 sels, and is, therefore, weaker than any other part ; that the formation of the pupil is 
 effected by the rupture of this membrane, and that this rupture is occasioned by the re- 
 traction of the vascular loops, which ultimately occupy the lesser border of the iris. 
 
 Uses of the Iris. — The iris regulates the quantity of light that is admitted into the in- 
 terior of the eye. The contraction of the pupil is an active movement, and its dilatation 
 is passive ; facts which are opposed to the doctrine of its muscularity, but support the 
 idea of its being a vascular and erectile structure. 
 
 It has been stated that the movements of the iris are intended to enable us to judge 
 of the distance and size of objects, or, rather, to enable us to see objects at different dis- 
 tances : this is erroneous, for the pupil remains of the same size, under the action of a 
 similar quantity of light, whether the object looked at be near or distant.* The effect 
 of narcotics, and especially of belladonna, either applied topically, or taken internally, in 
 producing dilatation of the pupil, is one of the most curious facts concerning the iris. 
 The direct action of the rays of light upon the iris has no influence upon the size of the 
 pupil, the dimensions of which are altered either by the action of light upon the retina, 
 or in consequence of a peculiar condition of the optic nerve of the brain 
 
 The Pigment of the Eye. 
 
 It has been stated that the external surface of the choroid and the internal surface of 
 the sclerotic are coloured by a very thin layer of pigment ; and also that the internal sur- 
 face of the choroid is covered with a thicker layer, which is itself thickest on the fore 
 part of that surface, near the ciliary body, between the greater ciliary processes, and be- 
 hind the iris. By means of this pigment the interior of the eye is converted into a true 
 dark chamber. StUl, it may be asked why the pigment is less abundant behind than in 
 front. 
 
 The choroid pigment is not black, but of a very dark-brown colour, like bistre ; in this 
 respect resembhng the pigment of the skin of the negro ; it consists of molecules or 
 globules insoluble in water. 
 
 The pigment of the choroid of the iris is wanting in albinoes. as well as the cutaneous 
 pigment. Both have the same chemical composition, t 
 
 * [The pupil certainly dilates in looking at distant objects, and contracts under the opposite circumstances ; 
 but it is by no means certain that the adjustment of the eye to objects at different distances depends on these 
 alterations in the condition of the iris.] 
 
 t [The pigment of the eye consists of nucleated cells containing the pigment granules ; on the inner surface 
 of the choroid these cells are flattened and hexagonal, and their sides fit accurately together, so as to present 
 an appearance like mosaic work ; on the back of the iris the cells are irregularly rounded. In albinoes the 
 cells contain no coloured granules.] 
 
mi 
 
 NEUROLOGY. 
 
 In some animals the pigment of the eye has a metallic lustre, and an iridescent aspect 
 in a great part of its extent. 
 
 The Retina. 
 The retina (r,figs. 241, 245), counting from without inward, is the third membrane ol 
 the eye ; it is the immediate seat of vision, and is an essentially nervous membrane, sit- 
 uated within the choroid and the sclerotic. Its external surface (jr,fi.g. 245) corresponds 
 to the choroid, from which it is separated by the pigment, which, in eyes that have un- 
 dergone slight decomposition, forms an irregular layer upon it, like a web. Dr. Jacob 
 (Philosoph. Trans., 1819) has described a serous membrane between the retina and the 
 choroid, in the cavity of which a dropsical effusion may occur, and constitute what is 
 called ;)os<enor staphyloma of the eye. M. Weber believes that this membrane is prolonged 
 forward to the circumference of the crystalline lens, and is then reflected over the pos- 
 terior surface of the iris, where it becomes continuous with the membrane of the aque- 
 ous humour. I have not succeeded in demonstrating the membrane of Jacob.* 
 
 The internal surface (r, fig. 246) of the retina is applied to the vitreous body, but does 
 not adhere in the slightest degree to it. 
 
 The point at which the retina terminates in front is still regarded by most anatomists 
 as undetermined. Several, with the older authors, describe it as extending to the cir- 
 cumference of the crystalline lens. Some entertain a modification of this opinion, be- 
 lieving that an extremely thin membrane is given off from the rim {r'r", fig. 241) in 
 which the retina seems to terminate, and that this membrane advances upon the inner 
 surface of the ciliary body to the front of the capsule of the crystalline lens, to which it 
 is attached. M. Duges, in an excellent work upon the comparative anatomy of the or- 
 gan of vision, expresses a somewhat different opinion : according to his view, the retina 
 having reached the ciliary processes, divides into numerous tongues, each of which passes 
 between two of the ciliary processes, and terminates by expanding upon the circumfer- 
 ence of the crystalline lens. A careful examination has proved to me distinctly that the 
 retina terminates by a defined edge (margo dentatus, r'r',fig. 241 ; m,fig. 245) at the 
 Fie 245 posterior extremities of the ciliary processes of the vitreous 
 
 body (a), to which processes it adheres rather firmly, though it 
 can be sometimes separated from them Avithout laceration. 
 
 Is the retina an expansion of the medullary part of the optic 
 nerve, or is it a special organ continuous with that nerve ! 
 Although the former of these opinions appears more probable 
 than the latter, still it is liable to objections. The optic nerve 
 is constructed in a particular manner as it passes through the 
 sclerotic, and the corresponding nervous substance is so ar- 
 ranged that pressure upon the nerve does not force the ner- 
 vous substance into the interior of the eye, though pressure 
 upon every other part of the nerve causes a white pulpy matter to exude from its divided 
 surface. 
 
 The retina is semi-transparent, like a thin layer of opal : it scarcely holds together, 
 and can be torn with the greatest facility. It does not appear to me to be thicker be- 
 hind than in front. 
 
 The radiated lines stated by several of the older anatomists, and also byM. Duges, to 
 exist in the retina, can only be distinguished behind at the entrance of the optic nerve. 
 Tliis radiated character was evident in the eye of an ox which I recently examined. The 
 optic nerve divided into three thick diverging bundles, which expanded into a layer ; but 
 this filamentous arrangement was soon succeeded by what appeared, at least, to be a 
 pulpy structure. 
 
 Two layers are described in the retina : an external, which is pulpy and nervous ; and 
 an internal, which is vascular, and is formed by the ramifications ol^ the arteria centralis 
 retinae ; but this subdivision of the retina is purely fictitious. Soemmering has given 
 a good representation of the vascular network, which seems in some manner to support 
 the nervous substance. 
 
 The Foramen Centrale, the Fold, and the Limbus Luteua vf the Retina^ — Soemmering 
 was the first to describe in the retina a foramen {foramen centrale), which had escaped 
 the researches of Ruysch, Zinn, and Haller, doubtless because it is concealed by the folds 
 formed by the retina at this point. 
 
 It is doubtful whether these folds of the retina result from the collapsed condition of 
 the eyeball, which necessarily follows the dissection required for the examination of its 
 interior ; or whether they are really part of its structure, and should be regarded as the 
 vestige of the singular folds existing in different kinds of animals, and especially in birds, 
 the visual powers of which are thereby greatly increased. However this may be, the 
 foramen, which is always situated to the outer side of the entrance {b, fig. 246) of the 
 
 * [If the posterior part of the sclerotic and choroid be carefully removed from a fresh eye (leaving the optic 
 nerve untouched), and the eye be then macerated a few hours in water, portions of Jacob's membrane will 
 either senarate, or they ca"n easily be separated from the outer surface of tlie retina.] 
 
THE VITREOUS BODY. 
 
 66] 
 
 optic nerve, is surrounded with a zone of a canary-yellow colour : this is the limhus lu- 
 teus foraminis centralis {Sammering), or the yellow spot of Sam- „. 
 
 mering (a). ^' 
 
 The foramen centrale and the limbus luteus exist in man and the 
 quadrumana only ; that is to say, in those cases only in which the 
 visual axes of the two eyes are parallel to each other, as in man. 
 
 I have not found that the yellow spot corresponds to the thick- 
 est part of the retina. 
 
 It should, moreover, be observed, that the foramen centrale, not 
 the entrance of the optic nerve, corresponds to the antero-posterior 
 axis of the globe of the eye, and is the true centre of the retina. 
 
 The uses of the central foramen and the yellow spot are not 
 known. 
 
 The yellow spot does not exist in the foetus.* 
 
 The Humours of the Eye. 
 The media through which the light passes in the eye, besides the transparent cornea 
 already described, are the vitreous body, the crystalline lens, and the aqueous humour. 
 
 The Vitreous or Hyaloid Body. 
 
 The vitreous or hyaloid body {v,Jigs. 247, 248) (from va?.oc, glass), so called from its re- 
 semblance to glass, is an imperfectly spheroidal, and quite transparent mass, which oc- 
 cupies the posterior three fourths (v,Jig. 241) of the globe of the eye ; it is covered im- 
 mediately by the retina {v, fig. 245), which is simply in contact with it, and indirectly by 
 the other coats of the back part of the eye, which are accurately moulded upon it. It pre- 
 sents a slight depression in front, for the reception of the posterior surface of the crys- 
 talline lens (/). The vitreous body and the crystalline lens together very nearly resem- 
 ble in form the entire globe of the eye, the projection of the crystalline lens representing 
 the prominence of the cornea (compare figs. 241 and 245). 
 
 The vitreous body is composed of a liquid, named the vitreous humour, i and of the hy- 
 aloid membrane. 
 
 The hyaloid membrane {h,fig. 241), which was first discovered by Fallopius, can be 
 easily demonstrated by puncturing the vitreous body, and allowing the vitreous humour 
 to escape. If it be then dipped in diluted nitric acid, the membrane will become opaque, 
 and easily distinguishable. This membrane not only forms a general investment or cap- 
 sule for the vitreous body, but gives off lamellar prolongations from its internal surface, 
 which separate the vitreous humour into an irregular number of compartments, or cells. 
 The existence of these cells can be easily proved by moving the vitreous body between 
 the fingers ; and if this body be frozen, their shape is shown by that of the masses of ice 
 which may be taken from them. 
 
 It is generally admitted that all these cells communicate with each other ; because, 
 when one of them only is punctured, all the vitreous humour will gradually escape. 
 Still, I have several times observed that the eye did not collapse when a part of the vit- 
 reous body had escaped in the operation for extracting a cataract ; this, however, might 
 have depended upon any farther escape being opposed by the approximation of the lips 
 of the incision. 
 
 The manner in which the hyaloid membrane is arranged with reference to the crys- 
 talline lens is still a disputed point. It is generally admitted that, about a line from the 
 margin of the crystalline lens, the hyaloid membrane divides into two layers, one of 
 which passes behind {h,fig. 241) and the other in front of the 
 lens. The three-sided interval (s s) which exists all round the 
 crystalline lens, and which has been described by Fran9ois Petit, 
 under the name of canal godronne, is formed between these two 
 layers and the lens. This circular canal, or canal of Petit, can 
 be very easily shown by blowing air into it (as in p,fig. 247) ; 
 it is then seen to be constricted at intervals, as if by small folds 
 or bands, so that it presents a knotted or plaited appearance. 
 Other anatomists, on the contrary, state that the hyaloid mem- 
 brane does not split into two layers, but passes altogether behind 
 the crystaUine lens, in order to cover the front of the vitreous body. 
 
 Fi>. 247. 
 
 It is certain that 
 
 * [From recent researches, especially those of Valentin and Hanover, the following appears to be the mi- 
 nute structure of the retina: 1. The membrane of Jacob consists of minute cylindrical or prismatic bodies, 
 placed closely together, and perpendicularly to the surface of the membrane ; among these are somewhat lar- 
 ger bodies, "coni gemini," which might be compared in shape to two cylinders applied to each other length- 
 wise. Both kinds of bodies are attached by one extremity to the inner surface of the choroid, being received 
 into exceedingly minute sheaths, which rise from the surface of the pigment cells. 2. The filaments of the 
 optic nerve spread out on the inner surface of this structure, and, according to Valentin, have a plexiform ar- 
 rangement, but their mode of termination seems doubtful. This nen-ous expansion is covered on its outer and 
 also on its inner surface by a layer of ganglionic globules.] 
 
 t [The vitreous humour, according to Ilerzelius, contains 98'4 per cent, of water ; its solid matter consists 
 of albumen, extractive matter, and chloride of sodium.] 
 
662 NEUROLOGY. 
 
 a circular layer, having the form of a radiated crown, is given off from the anterior part 
 of the hyaloid membrane ; this circular radiated disk w^as described by Petit and Cam- 
 per, but it is called the corona ciliaris, or the zonula Zinni : it corresponds accurately to 
 the ciliary processes and ciliary body of the choroid coat. 
 
 The ciliary zone of Zinn (a, Jig. 245, b, figs. 247, 248), or the ciliary processes of the vit- 
 Fig.m. reous body, can be seen through that transparent body {d,fig. 241) 
 
 when the several coats are removed from the back part of the 
 globe of the eye : it is completely exposed to view when the cho- 
 roid coat and the iris are separated from the vitreous body {fig. 
 248). It is this structure which constitutes the beautiful radiated 
 crown situated in front of the vitreous body around the crystalline 
 lens, and which extends considerably beyond the ciliary body of 
 the choroid ; it consists of alternate black and transparent rays, 
 and is generally regarded as a reverse impression of the ciliary 
 processes of the choroid. The ciliary processes of the vitreous 
 body correspond to the black lines, and the intervals between the 
 processes to the transparent rays. 
 
 The ciliary processes of the vitreous body are not so thick as those of the choroid ; 
 but the folds of which they consist commence farther back than the ciliary processes of 
 the choroid, so that the radiated disc formed by them is larger than that formed by the 
 processes of the choroid. These folds of the vitreous body have the same spongy and 
 jagged appearance as those of the choroid : they have no free portion, or, rather, that 
 part of the zone of Zinn (a, fig. 248) which corresponds to the free portion of the ciliary 
 processes of the choroid is applied to the crystalline lens. 
 
 The cihary processes of the choroid and those of the vitreous body are so arranged 
 that those of the one are received in the intervals between those of the other. It ap- 
 pears to me difficult to determine whether they are simply applied to each other, or 
 whether their structure is continuous. However, on examining these parts through a 
 lens while they are being separated, it has appeared to me that a sort of cellular struc- 
 ture was lacerated, and that the black pigment, which had been hitherto confined, es- 
 caped together with a little fluid. M. Ribes believes that, during this separation, some 
 shreds of the hyaloid membrane are drawn away with the ciliary processes of the choroid. 
 The inner border (a) of the cihary zone of Zinn is in contact with the margin of the 
 crystalline lens (/), and adheres rather firmly to it. Around the outer border, which ex- 
 tends beyond the ciliary body of the choroid, are found the origins of certain radiated 
 folds (i), which form, as it were, the commencement of the ciliary processes. This bor- 
 der adheres to the anterior margin of the retina {m, fig. 245), which appears to me to be 
 thickened and shghtly uneven in this situation, and not to be continuous with the hya- 
 loid membrane. 
 
 From what has been stated, it follows that the canal of Petit is formed between the 
 hyaloid membrane and the zone of Zinn, and that the crystalline lens is fixed by this 
 zone to the anterior margin of the vitreous body ; that the anterior surface of the crys- 
 talline lens is not covered by a prolongation of the hyaloid membrane, besides its own 
 capsule ; and that the retina does not reach as far as the margin of the crystalline lens. 
 M. Jules Cloquet has described, under the name of the hyaloid canal, a cylindrical pas- 
 sage, which is formed by the reflection of the hyaloid membrane into the interior of the 
 vitreous body around the nutritious artery of the lens, and which, like that artery, trav- 
 erses the vitreous body from behind forward. I have never been able to see this canal. 
 No vessels have been demonstrated in the hyaloid membrane ; it does not receive 
 any from the retina, and yet we cannot doubt that it is provided with them. Although 
 the structure of the ciliary processes of the vitreous body is little known, yet, as it is 
 probable that it is similar to that of the ciliary processes of the choroid, and, therefore, 
 essentially vascular, it may be, as stated by M. Ribes, that the materials for the forma- 
 tion and nutrition of the lens and of the ciliary processes of the vitreous body are con- 
 veyed to both of these parts through the vascular ciliary processes of the choroid. 
 
 The Crystalline Lens and its Capsule. 
 
 The crystalline lens {I, figs. 241, 244, 245, 248) is a transparent body, having the form 
 of a lens, as its name implies ; it is situated at the junction of the posterior three fourths 
 with the anterior fourth of the globe of the eye, and is placed between the vitreous body, 
 which is behind, and the aqueous humour, which is in front {see fig. 241). 
 
 Its axis corresponds to the centre of the pupil. 
 
 It is shaped like a double convex lens, the posterior surface of which is more convex 
 than the anterior. From some very exact and minute investigations which have been 
 made upon this point by Fran5ois Petit and others, it appears that both the relative and 
 the absolute convexity of the two surfaces of the crystalline lens are subject to great 
 varieties in different individuals ; that, in general, the posterior convexity forms part of 
 a circle from four to five lines in diameter, while the anterior forms part of one from six 
 to nine lines in diameter. In some subjects the degree of curvature of the two surfaces 
 
THE CRYSTALLINE LENS AND ITS CAPSULE. 668" 
 
 of the crystaDine lens is almost equal. In the foetus the crystalline lens approaches the 
 spheroidal form, which is that which it has in fishes. 
 
 The anterior surface of the crystalline lens corresponds to 'the iris, from which it is 
 separated by the aqueous humour. It has been incorrectly stated by Winslow that the 
 crystalline lens pushes the iris forward : there is a space between the crystalline lens 
 and the iris which constitutes the posterior chamber of the eye. The anterior surface 
 of the lens may be seen through the pupil, so that slight shades of difference in the col- 
 our of the lens may be detected. When the pupil is very much dilated, the anterior sur- 
 face of the lens is entirely exposed. 
 
 Its posterior surface is in relation with the vitreous body, which is depressed so as to 
 receive it. This surface does not adhere to the hyaloid membrane. When dissecting 
 a subject of twenty-seven years of age who had suffered with hydrophthalmia in both 
 eyes, M. Ribes found about six grains of a limpid fluid between the hyaloid membrane 
 and the crystalline lens ; so that the space occupied by tliis fluid might have been taken 
 for a third chamber. 
 
 The margin of the lens {I, fig. 248) is set (like the stone of a brooch) in the ciliary pro- 
 cesses (a) of the vitreous body, which cover and adhere to the fore part of that margin, 
 so that the lens is kept firmly in its place. Its margin is surrounded by the canal of 
 Petit {fig. 247). 
 
 The crystalhne lens presents different shades of colour at different periods of life. It 
 is reddish in the foetus, but is perfectly transparent after birth ; in the adult, it becomes 
 slightly opaline at the centre ; in the aged, it acquires a yellowish opacity, which ap- 
 proaches somewhat to the colour of amber or topaz. Morbid opacity of the lens consti- 
 tutes lenticular cataract. 
 
 The crystalline lens consists of a capsule, and of a proper substance enclosed within it. 
 
 The Substance of the Crystalline Lens. — When stripped of its capsule, the crystalhne 
 lens is found to have three degrees of consistence, at different parts : thus, at its sur- 
 face, it is almost of a liquid softness ; below this, it is soft and gelatinous, and may be 
 crushed by the finger — this is the cortical layer ; and, lastly, it is hard in the centre, which 
 is called the nucleus, and closely resembles a mass of gum-arabic. The most superficial 
 and fluid layers constitute the liquor Morgagni. 
 
 The substance of the crystalline lens consists of concentric layers {b c, Jig. 249), which 
 can be very easily demonstrated, even 
 without any previous preparation, but 
 are rendered most distinct by boiling, 
 or immersion in a diluted acid. The 
 crystalline lens then separates into su- 
 perimposed laminae or scales, like the 
 bulb of the onion. 
 
 The different degrees of consistence 
 observed in the substance of the lens 
 do not depend upon differences in na- 
 ture, but upon mere modifications. When hardened by an acid, the structure of the lens 
 is exactly the same throughout : even the liquor Morgagni appears to become laminated. 
 
 Each of these concentric lamina; is itself composed of radiated fibres (a. Jig. 249), 
 which can be readily seen without dissection, by placing one of them upon a black sur- 
 face, and examining it through a lens, or even by a strong Ught. 
 
 Lastly, the crystalline lens, when boiled, or submitted to the action of an acid, splits 
 into three, four, or even a greater number of triangular segments (ab), all of which unite 
 by their summits at the centre of the lens, so that its anterior and posterior surfaces 
 have a stellate appearance.* Pathologists have successfully applied this anatomical 
 fact to the explanation of the stellate forms of cataract, in which the opacity branches 
 out in three or more directions. 
 
 What is the nature of the crystalline lens 1 Is it the product of a secretion 1 or is it 
 an organized structure 1 M. Duges has recently supported by his authority and by ad- 
 ditional facts the opinion of Dr. Young, who believed that the crystalline lens is not only 
 an active organized structure, supplied with vessels and veins, but that it is even mus- 
 cular and possessed of contractility, so as to be able of itself to increase or diminish its 
 curvatures and its density, thus endowing the eye with the power of adjusting itself to 
 the different distances %f the objects to be seen. The substance of the lamina; of the 
 crystalline lens has, indeed, a linear structure ; but it does not at all resemble muscular 
 tissue, either in its consistence or in its regularly stratified character. I conceive, 
 therefore, that I am warranted in regarding the superimposed layers of the crystalline 
 lens as the solidified product of a secretion formed by its capsule, t 
 
 * See note, infrd. 
 
 t [The lines indicating- the divisions between the triangular segments of the lens (a, Jig- 249) are called sep- 
 ta; the septa of the anterior surface are placed opposite the intervals between the septa of the posterior sur- 
 face. The fibres of which the laminie are composed have a linear arrangement, and, as discovered by Sir D. 
 Brewster, are fitted into each other by indented margins {Jig. 250). Schwann has shown that those fibres 
 are developed from rounded, nucleated cells, which become elongated into fibres, the margins of which sub- 
 
The capsule of the crystalline lens (jt,fig- 241) is accurately fitted to the lens itself; iff 
 the healthy state it is transparent, but may become opaque, and thus constitute a mem- 
 branous or capsular cataract. 
 
 Its external surface is free in front, where it is bathed by the aqueous humour : it is 
 merely in contact with the hyaloid membrane behind, but its circumference adheres in- 
 timately to that membrane, or, rather, to the ciliary zone of Zinn. 
 
 Its internal surface does not appear in the slightest degree adherent to the lens. If 
 an incision be made into this capsule in the living subject, the lens is forced out merely 
 by the tonicity of the coats of the eye. The anterior segment of the capsule is twice as 
 thick as the posterior : it might be compared to a layer of the cornea,* 
 
 It receives bloodvessels derived from the arteria centralis retinae. t These vessels, 
 according to Meckel, are distributed only upon the posterior half of the capsule ; those 
 which belong to the anterior half arise from the vessels of the ciliary processes. 
 
 Some anatomists believe that these vessels send ramifications between the different 
 concentric laminae of the crystalline lens for its nutrition ; but I am not aware that they 
 have ever been demonstrated. 
 
 No nerves have been discovered in the crystalline lens. M. Duges believes that the 
 retina gives off some net vous filaments which reach as far as the lens, and spread out 
 upon its capsule ; but, after the most careful examination, I am convinced that such is 
 not the case. 
 
 The Aqueous Humour and, its Membrane. 
 
 The term aqueous humour is applied to a perfectly limpid and transparent fluid, which 
 occupies the two chambers of the eye. These two chambers, which have been correctly 
 understood only since the discovery of the true seat of cataract in the crystalline lens, 
 correspond to that small portion of the cavity of the eye which is situated between the 
 cornea and the lens {see fig. 241). The space between these two parts is divided un- 
 equally by the iris (i) into two chambers : an anterior and larger, which is called the an- 
 terior chamber; and a posterior and smaller, named the -posterior chamber. These two 
 chambers communicate through the pupil (jpi). The existence of the posterior chamber 
 was long disputed, but it may easily be proved by freezing the eye ; and by the same 
 experiment we may obtain an approximation to the relative capacity of the two cham- 
 bers, which will be found as 3 to 1, the anterior being decidedly the larger. 
 
 The total quantity of the aqueous humour is about five grains ; 100 parts of it are 
 found to contain 981 of water, with traces of albumen and chloride of sodium. 
 
 The Membrane of the Aqueous Humour. — It is now generally admitted that the aqueous 
 humour is secreted by a special membrane, called the membrane of the aqueous humour, or 
 membrane of Demours, although it had been previously described by Zinn and Descemet. 
 This membrane, according to Demours, hues the posterior surface of the cornea {m,fig. 
 241), and is reflected upon the front of the iris. At this point, according to most anat- 
 omists, it is lost, and cannot be traced to the pupil ; but, according to others, it proceeds 
 as far as the pupil, and there terminates ; and, lastly, some believe that it is reflected 
 through the pupil, in order to cover the posterior surface of the iris, where it retains the 
 pigment in its situation. 
 
 It is easy to detach a tolerably thick and strong layer, of a cartilaginous aspect, from 
 the posterior surface of the cornea, either after long-continued maceration, or after slight 
 boiling ; but it is not shown that this is anything more than the posterior layer of the 
 cornea, which it resembles in appearance. 
 
 It is only from analogy that the existence of the membrane of the aqueous humour 
 can be admitted. 
 
 We cannot demonstrate anatomically its reflection upon the outer border of the iris ; 
 and, moreover, it is certain that it does not exist upon either surface of that membrane. 
 
 According to M. Ribes, the aqueous humour is supplied by the vitreous body, and is 
 poured into the posterior chamber by the canals said by him to exist in the substance of 
 the ciliary processes of the vitreous body. This opinion is founded, 1. Upon an exper- 
 iment which consists in carefully removing the cornea, and suspending the eye by the 
 optic nerve, when the vitreous humour will exude from the wound of the cornea, so that, 
 in less than twenty-four hours, two thirds of that body will have escaped ; and, 2. Upon 
 the observation of cases of imperfect iris, in which, according to M. Ribes, the aqueous 
 Fig. 250. • 
 
 — - sequently become dentated ; the lens, therefore, resembles some other non-vascular parts 
 
 (as the horny tissues) in its mode of growth. It consists, according to Berzelius, of 58"0 
 per cent, of water, 3'7 of extractive and salts, 2'4 of membrane, and 35"9 of a peculiar 
 Bubstanee, which, except in its colour, resembles the colouring matter of the blood. 
 
 * According to M. Ribes, whom I always have pleasure in quoting, btcause his re- 
 searches are worthy of every confidence, " by examining the internal surface of the crys- 
 talUne capsule in a good light, and with a good lens, a series of transverse fissures are 
 observed around its entire circumference, where the anterior and posterior segments of 
 the capsule unite. I could never satisfy myself whether these fissures corresponded to 
 the ciliary processes of the vitreous body, or to the villous fringes of the ciliary processes 
 of the choroid." 
 
 T Vide fig. v., pi. 6, of Soemmering's Icones Oculi Humani. 
 
THE ORGAN OP HEARING. 
 
 Bnrhdur is contained entirely in the posterior chamber. He believes that the free por- 
 tion of the vitreous ciliary body has the power of absorbing this liquid. 
 
 M. Duges adopts the following modification of this opinion : the canal of Petit, accord- 
 ing to him, is divided into as many compartments as there are ciliary processes. It re- 
 sembles, therefore, a collection of short canals directed from before backward, rather 
 than a single circular canal ; these short canals communicate behind with the vitreous 
 body, and open in front by certain slits or perforations existing in the Zone of Zinn, which 
 enable the aqueous humour secreted by the vitreous body to escape in front of the crys- 
 talline lens. 
 
 Haller has stated all the opinions which have been entertained regarding the produc- 
 tion of the aqueous humour, which has been said to be secreted by the vitreous body, 
 as believed by MM. Ribes and Duges, by the ciliary processes, by the choroid, by the 
 iris, and, lastly, by certain special ducts proceeding from without the eye, and perfora- 
 ting the sclerotic at its junction with the cornea. 
 
 The Vessels and JVerves of the Eye. 
 
 The arteries of the eye are the following : a considerable number of short posterior cil- 
 iary arteries, which surround the optic nerve, perforate the sclerotic near it, and ramify 
 in the choroid, m the ciliary processes, and in the iris ; the anterior short ciliary, which 
 perforate the anterior part of the sclerotic, and are distributed to the iris ; the long cilia- 
 ry arteries, two in number, which run between the sclerotic and the choroid, as far as 
 the outer border of the iris, and then, bifurcating and curving inward, anastomose with 
 each other around that border. From the vascular circle thus formed most of the ves- 
 sels of the iris are given off. The central artery of the retina {arleria centralis retina) en- 
 ters the globe of the eye through the centre of the optic nerve (at the porus opticus, b, 
 fig. 246), and, sending off a branch to the crystalline lens, which traverses the vitreous 
 body from behind forward, covers the internal surface of the retina with its other rami- 
 fications. 
 
 The veins correspond to the arteries, but are much more numerous. The posterior, 
 or short ciliary veins, form vortices or whorls in the choroid, and are hence called vasa 
 vorticosa (v, fig. 244). All the veins of the globe of the eye open into the ophthalmic and 
 angular veins. 
 
 The nerves of the eye consist of a special nerve called the optic nerve, the origin, course, 
 and structure of which will be described hereafter (see Cranial Nerves) ; and, second- 
 ly, of the ciliary nerves, which are derived from the fifth nerve, either directly from its 
 nasal branch, or indirectly from the ophthalmic ganglion. These nerves (a a, fig. 242) 
 are distributed to the ciliary ligament, and to the iris. 
 
 The Organ of Hearing 
 
 Hearing is that sense by which we perceive the vibrations of the air, which produce 
 tound. 
 
 The organ of hearing is not situated in the face, like those of the other senses, but is 
 contained in the substance of the base of the cranium, in the petrous portion of the tem- 
 poral bone, its deep situation preserving it from external violence : it is composed essen- 
 tially of a membranous and nervous apparatus contained in an extremely complicated 
 osseous cavity, named the labyrinth or internal ear. 
 
 The labyrinth if, fig. 251) communicates with the exterior by means of an acoustic 
 trumpet formed by the auricle, or pinna (a), and external audita- p^g 251. 
 
 ry meatus (b), and named the external ear, which may be regard- 
 ed as an apparatus for collecting sonorous undulations. 
 
 The term middle ear, or tympanum, is applied to a cavity (d) 
 which is placed between the labyrinth and the external ear, and 
 may be considered as an apparatus for modifying sounds, the 
 intensity of which is increased or diminished by it, according 
 as they happen to be weak or loud.* It follows, therefore, that 
 the ear is formed by a succession of cayities, which, proceed- 
 ing from without inward, are, the external ear, consisting of 
 the auricle and external auditory meatus, of the middle ear, or 
 tympanum, and of the internal ear, or labyrinth. I shall de- 
 scribe the ear in this order, and shall thus proceed from the less to the more complica- 
 ted parts of this organ. 
 
 The External Ear. 
 
 The exiexnal ear resembles a funnel or ear-trumpet, the expanded part of which rep- 
 resents the auricle, while the contracted portion corresponds to the external auditory 
 meatus. + 
 
 * M. Richerand (Elemens de Physiologie, first edit.) has drawn an excellent comparison lictween the uses of 
 the tympanum in hearing-, and those of the iris in vision. 
 
 1 The external ear, properly speaking, only exists in mammalia- and eren among- mammalia, those -which 
 do not hve constantly in the air are not proirjded with it. 
 
 4P 
 

 NEUROLOGY 
 
 The Auricle. 
 
 The auricle of the ear {auricula, 'pimia), commonly called the ear, is placed at the side 
 of the head, behind the articulation of the lower jaw, and in front of the mastoid process ; 
 it is an oval elastic lamina, folded in various ways upon itself, and having an undulated 
 surface. 
 
 The auricle or pinna is free above, behind, and below, but is so firmly attached in front 
 and on the inner side, that the two ears can support the weight of the entire body. 
 
 The individual varieties in the shape, direction, prominence, and size of the auricle 
 are generally known. Of these varieties, some are congenital, and others acquired. 
 Among the latter should be noticed the effects produced by the habit of confining the 
 entire ear more or less closely by the head-dress. The direction or prominence of the 
 auricle is not without some influence upon hearing, the perfection of which sense, ac- 
 cording to Mr. Buchanan, depends on the kind of angle formed by the auricle with the 
 side of the face, and which should be from 25° to 30°. 
 
 The internal or mastoid surface of the auricle presents certain eminences and depres- 
 sions, which correspond inversely with those on its external surface. 
 The external surface is remarkable for the alternate ridges and depressions observed 
 Fig. 252. upon it : at its centre, but somewhat nearer to the lower than the up- 
 
 per part, we find the concha (a, fig. 252), a funnel-shaped excavation, 
 the form and expansion of which are familiar to all, and at the fore 
 part of the bottom of which is found the orifice of the external audito- 
 ry meatus. 
 
 The concha is bounded in front by the tragus {h ), a triangular pro- 
 cess, the adherent base of which is turned forward and inward, while 
 iM^n~JljiS^ its free apex is directed backward and outward : it advances like a 
 lid over the orifice of the external auditory meatus, which is com- 
 pletely closed by its depression. The posterior surface of the tragus, 
 which forms part of the concha, is covered with stiff hairs, especially 
 in old subjects ; whence its name of tragus, from rpdyog, a goat. The 
 use of these hairs is to arrest any small particles that are floating in the air. 
 
 Behind and below, that is, opposite the tragus, the concha is bounded by the anti-tra- 
 gus (c), a triangular tongue, which is smaller than the tragus, and is separated from it 
 by a wide, deep, and rounded notch, named the notch of the concha (incisura tragica). 
 
 Behind and above, the concha is bounded by the anti-helix (e), a curved fold, which 
 commences above the anti-tragus, being separated from that part by a slight depression, 
 passes upward and forward, bifurcates, and then ends in the groove of the helix. The 
 superior branch of the bifurcation of the anti-helix is broad and smooth, while the inferi- 
 or is sharp ; between them is situated a slight depression, called the scaphoid, or navicv^ 
 lar fossa, but which would be more correctly named Vae fossa of the anti-helix (/). 
 
 The term helix {ili^, a roll, from kTiiacu, to roll around) is applied to a curved fold 
 {g g), which forms the external border of the auricle : it commences in the cavity of the 
 concha, which it divides into two unequal parts, one superior and narrow, the other in- 
 ferior and broader ; gradually increasing in size, it then passes upward and forward above 
 the external meatus, then above the tragus, from which it is separated by a very distinct 
 furrow : it next runs directly upward, curves backward, descends to form the posterior 
 margin of the auricle, and terminates by becoming continuous with the anti-helix in 
 front, and with the lobule {I) behind. 
 
 The groove or furrow of the helix is the groove (i) which surrounds the helix, and sep- 
 arates it from the anti-helix. 
 
 The lobule occupies the lower or small extremity of the auricle, from the rest of which 
 it is distinguished by its softness ; it is surmounted by the tragus in front, by the anti- 
 tragus behind, and by the notch of the concha in the middle. The lobule of the ear va- 
 ries exceedingly in size in different individuals, and is the part to which ear-rings are 
 generally appended. 
 
 The Structure of the Auricle. — The cartilage of the ear {figs. 253, 253*) constitutes the 
 
 Fig. 253. 
 
 Fig. 253.* 
 
 framework of the auricle, in a great measure deter- 
 mines its shape, and is the cause of its phability and 
 elasticity. 
 
 When the skin is removed from it, this cartilage, 
 therefore, presents certain eminences and depressions, 
 corresponding, with some exceptions, to those already 
 described as existing upon the surface of the auricle. 
 The cartilage of the ear has no part corresponding with 
 the lobule : again, the cartilaginous fold which consti- 
 tutes the helix terminates at the middle of the concha, 
 from whence it is continued by a fold of skin, which, 
 moreover, covers it throughout, and increases its prominence. Upon the cartilage of the 
 auricle we also observe the following parts : 1. A mammillated eminence {a, fig. 253V 
 
THE AURICLE. 667 
 
 called the p-ocess of the helix : it is of considerable size, is very dense, and arises from 
 the anterior margin of the helix, above the tragus. This process gives attachment to a 
 ligament. 
 
 2. A tail-shaped tongue of .cartilage (5), separated from that of the anti-tragus and 
 concha by a very long fissure, which is occupied by ligamentous fibres. This tongue is 
 formed by the united ends of the helix and anti-helix, and is very thick and dense : 
 it may be called the caudal extremity of the helix and anti-helix ; it supports the base of the 
 lobule. 
 
 3. A well-marked thickening, situated opposite the concha, and characterized by a 
 dead white colour. This thickening occupies a vertically elongated portion of the mas- 
 toid surface of the concha, and terminates at the lower part of the auricular cartilage : 
 it seems to be intended to preserve the form of the concha, which cannot be flattened 
 unless this thickened portion of the cartilage is first divided. Several fissures or notch- 
 es are also found in the cartilage of the ear, which is thus imperfectly divided into sev- 
 eral pieces that are movable upon each other, and united together by ligaments. The 
 principal fissure, independently of that already described as existing between the anti- 
 tragus and the caudal extremity of the helix and anti-helix, are, a small vertical fissure 
 upon the anterior margin of the heUx ; another vertical fissure upon the tragus ; several 
 irregular notches in the helix ; and, lastly, a much more important fissure, to which I 
 shall have to allude in describing the external auditory meatus. It is situated between 
 the helix and the tragus, and is prolonged upon the outer half of the orifice of that meatus. 
 
 The skin of the auricle is remarkable for its thinness and transparency : hence the 
 sub-cutaneous vascular network can be seen through it without dissection ; it is no less 
 remarkable for its tension, and its close adhesion to the cartilage, upon which it is mould- 
 ed, so as accurately to reveal its form. The portion of skin which covers the concha is 
 especially remarkable for its great tenuity and intimate adhesion to the cartilage. 
 
 The skin upon the free border of the auricle adheres but slightly to, and projects be- 
 yond the helix ; the same fold of skin, when doubled upon itself and prolonged below the 
 helix, constitutes the lobule, which, together with the adjacent part of the free border 
 of the auricle, is nothing more than a duplicature of the skin, containing some soft fat. 
 A small quantity of fat is formed around the entire circumference of the auricle, but 
 none exists in other situations. 
 
 The skin of the ear is provided with sebaceous folhcles, which can be easily shown by 
 maceration, after the method employed by Soemmering, and which are most numerous 
 in the concha and the scaphoid fossa. 
 
 The ligaments of the auricle are divided into the intrinsic and the extrinsic ligaments. 
 
 The extrinsic ligaments are, the posterior ligament, which is a thick, tendinous layer, ex- 
 tending from the concha to the mastoid process ; the anterior ligament, which is a triangu- 
 lar, very broad, and very strong hgament, arising from the process of the helix and the ad- 
 jacent part of the border of the helix, and terminating at the zygomatic arch, where it is 
 blended with the superficial temporal fascia ; and, lastly, the ligament of the tragus, which 
 is very strong, and extends from the tragus to the adjacent part of the zygomatic arch. 
 
 The intrinsic ligaments, the object of which is to keep the cartilage of the auricle fold- 
 ed upon itself, are, the ligament which keeps the caudal extremity of the helix applied 
 to the concha ; the very strong ligament which extends from the tragus to the helix, and 
 . unites the outer half of the auditory meatus to the cartilage of the auricle ; some very 
 strong bundles, which are situated upon the mastoid surface of the auricle, and are in- 
 tended to preserve its convolutions, for when they are divided the auricle may be un- 
 folded ; lastly, those most remarkable ligamentous bundles, which occupy the fold pre- 
 sented by the inferior branch of the bifurcation of the anti-helix. 
 
 The three extrinsic muscles of the ear, which exist in a rudimentary condition in the 
 human subject, but are so highly developed in timid animals, are intended to move the 
 auricle as a whole (see Myology). 
 
 The intrinsic muscles move the different parts of the auricular cartilage upon each oth- 
 er. Like the extrinsic, they are quite rudimentary. There is no difference in their size 
 in savage and civilized races. They are five in number, four of them being situated on 
 the concave, and one only on the convex, or mastoid surface of the auricle. 
 
 The great muscle of the helix (helicis major, c, fig. 253) is situated vertically upon the 
 anterior part of the helix, near the tragus ; it is a narrow, oblong tongue, fleshy in the 
 middle, and tendinous at its extremities ; its fibres are vertical. 
 
 The small muscle of the helix (helicis minor, d), the smallest of the intrinsic muscles of 
 the ear, lies upon that portion of the helix which divides the concha into two parts. 
 
 The muscle of the tragus (tragicus, e) is a broad band, lying upon the external surface 
 of the tragus ; its fibres are directed vertically. 
 
 The muscle of the anti-tragus (anti-tragicus,/) is a tongue-like bundle, which covers 
 the external surface of the anti-tragus, and is inserted by a tendon to the upper part of 
 the caudal extremity of the helix. Its use may be to move this caudal extremity upon 
 the anti-tragus. 
 
 The fifth is the transverse muscle (transversus auriculae, a, fig. 353*), which is situated 
 
 4 
 
NEUROLOGY. 
 
 on the mastoid surface of the auricle. According to Soemmering, it consists of a trans- 
 verse layer of fibres of unequal length, which spread out in a semicircular form from the 
 convexity of the concha to the ridge, corresponding to the groove of the helix. I doubt 
 the muscularity of these fibres, which I am inclined to regard as constituting an intrin- 
 sic ligament intended to preserve the fold of that portion of the anti-helix by which the 
 concha is bounded behind and above. 
 
 The arteries of the auricle are the posterior auricular, a remarkable branch of which 
 passes through the cartilage, between the caudal extremity of the helix and the concha, 
 so as to ramify in the cavity of the concha. All the branches of the posterior auricular 
 arteries turn over the free border of the helix, so as to reach the concave surface of the 
 auricle. The anterior auricular arteries arise from the external carotid and the tempo- 
 ral, and divide into inferior branches or arteries of the lobule and ascending branches. 
 The vei7is have the same names and follow the same course as the arteries. 
 
 The nerves of the auricle are derived from the auricular branch of the cervical plexus ; 
 three or four of them ramify upon the internal surface of the auricle. A remarkable branch 
 perforates the cartilage between the anti-tragus and the caudal extremity of the helix, 
 and is distributed to the skin which lines the concha.* 
 
 The External Auditory Meatus. 
 
 The external auditory meatus {b,fig. 251) is a partly cartilaginous and partly osseous 
 canal, extending from the concha (a) to the membrane of the tympanum (c). It fonns the 
 narrow portion of the ear-trumpet represented by the external ear. 
 
 It is about an inch in length. Its section represents an ellipse, of which the longest 
 diameter is vertical. Its direction is transverse, and it describes a very slight curve, 
 having its convexity turned upward. Moreover, near its external orifice it is bent at an 
 angle which projects upward, and hence it is necessary to draw the auricle upward and 
 backward, if we wish to examine the bottom of the external auditory meatus. 
 
 The external meatus is in relation with the temporo-maxillary articulation in front, 
 with the mastoid process behind, and with the parotid gland below. 
 
 Its external orifice, which is vertically oblong, more or less widened out in different in- 
 dividuals, and covered with hairs in old age, occupies the anterior and inferior part of 
 the concha behind the tragus, which serves as a lid for it. It is bounded behind by a 
 sort of semilunar ridge, which projects more or less forward in different individuals, so 
 as to contract its orifice to a greater or less extent. In front of the auditory meatus 
 there is an excavation or fossa concealed by the tragus, and named the tragic fossa of 
 the co7icha ; it forms, as it were, the vestibule of the meatus. 
 
 The internal orifice of the auditory meatus is circular : it is directed very obliquely 
 downward and inward, and is closed by the membrana tympani. 
 
 Structure. — The auditory meatus consists of an osseous portion, and of a cartilaginous 
 and fibrous part. 
 
 The osseous portion has been already described with the temporal bone, as the external 
 auditory meatus. It is wanting in the foetus, and in the new-born infant, in whicli its 
 place is supplied by the tympanic ring or circle. We have stated that, in the adult, this 
 ring forms an osseous lamina distinct from the rest of the temporal bone, that it rests 
 behind upon the mastoid and styloid processes, for the latter of which it forms the vagi- 
 nal process, and that it is separated in front from the auricular portion of the glenoid 
 cavity by the fissure of Glasserius ; this lamina forms both the anterior and inferior walls 
 of the auditory meatus and cavity of the tympanum. 
 
 The cartilaginous and fibrous portion forms the outer half of the external auditory mea- 
 tus, and may be separated from the cartilage of the auricle by a careful dissection. If 
 an incision be made over the similunar ridge which constitutes the outer border of the 
 orifice of the auditory meatus, it will be seen that this ridge is formed by the juxtaposi- 
 tion of two cartilaginous borders, one of which belongs to the concha, and the other to 
 the auricle, and which are united by fibrous tissue. If the dissection be continued be- 
 tween the tragus and the corresponding part of the helix, the auricle may be separated 
 from the auditory meatus, exceping below, where their continuity is established by means 
 of a tongue or isthmus of cartilage. 
 
 The tragus belongs essentially to the auditory meatus, the cartilage of that canal being 
 merely a prolongation of the tragus folded upon itself (see b,fig. 253*), so as to form- the 
 lower two thirds or three fourths of a cylinder. The inner end of this imperfect cylin- 
 der is attached to the rough external rim oi the osseous portion of the meatus by means 
 of a fibrous tissue, which extends farther above and behind than below and in front, and 
 which gives the cartilage a great degree of mobility ; there is a thick prolongation or 
 process at the lower and anterior part of the inner end of the cartilage of the meatus. 
 
 The fibrous portion of the auditory meatus forms the upper third or fourth of that canal, 
 and also fills up the large notch in the inner end of the cartilaginous portion. 
 
 * [The auricle also receives twigs from the posterior auricular branch of the facial nerve, from the auriculo- 
 temporal branch of the inferior maxillary division of the fifth nerve, and from a small branch of the pneumo- 
 fastric nerve. See description of those nerves.] 
 
THE TYMPANOM. 
 
 Near the tragus there are two or three fissures or divisions in this cartilage, named 
 the fissures of Santorini, which give it some resemblance to the rings of the trachea : 
 these fissures are at right angles to the length of the canal, and are filled up with a 
 fibrous tissue, which some anatomists have conceived to be mixed with muscular fibres, 
 or to consist entirely of muscular fibres intended to move the small and partially separa- 
 ted portions of the cartilage. It is evident that the mode in which the partly cartila- 
 ginous and partly fibrous portion is united with the osseous portion of the canal, and also 
 the existence of the fissures just described, have reference to the mobility of the entire 
 canal. 
 
 The internal surface of the auditory meatus is lined by a prolongation of the shin, 
 which is remarkable for its extreme thinness. It becomes thinner and thinner in ad- 
 vancing from the orifice to the bottom of the meatus ; and the fineness and extreme del- 
 icacy of that portion of the skin which corresponds to the osseous part of the meatus 
 deserves special attention. The skin of the meatus is also characterized by being cov- 
 ered in all parts with fine downy hairs ; a fact which proves that it is of a cutaneous 
 structure, and not a mucous membrane. In old subjects, there are some tolerably long 
 hairs at the commencement of the auditory meatus, as well as upon the internal surface 
 of the tragus ; they prevent the entrance of dust and insects, which, moreover, get in- 
 volved in the ceruminous secretion. 
 
 The skin of the meatus is farther characterized by the presence of a number of se- 
 baceous follicles, or glands, called the ceruminous glands,* the orifices of which are vis- 
 ible to the naked eye, and give the skin an areolar appearance. These small glands oc- 
 cupy the entire inner surface of the cartilaginous and fibrous portions of the auditory 
 meatus : from their yellowish-brown colour, they can be readily seen in oblique sections 
 of the skin. They secrete a rather thick unctuous substance, resembling wax, whence 
 it is called cerumen {cera, wax). It is very bitter, and is partially soluble in water, with 
 which it forms an emulsion which leaves a greasy stain upon paper ; it sometimes be- 
 comes exceedingly hard from remaining long in the passage, and then acts as a mechan- 
 ical cause of deafness. By analysis, this substance, according to Berzelius, yields a 
 fatty oil, an albuminous substance, and a colouring matter, and, according to Rudolphi, 
 a bitter principle like that of the bile. Nature intended, says Soemmering, that there 
 should be a sufficient quantity of cerumen, not only to keep out insects, but also to di- 
 minish the intensity of sonorous vibrations. It is, therefore, a bad habit to remove it 
 artificially, unless there be an abnormal accumulation of this substance. 
 
 The Middle Ear, or Tympanum. 
 
 Dissection. — The cavity of the tympanum may be laid open, either from its external 
 wall, by removing the membrana tympani, or from its upper wjdl, by cutting away the 
 anterior part of the base of the petrous portion of the temporal bone with a strong scal- 
 pel ; the situation in which this may be done is indicated by a fissure, or, rather, a su- 
 ture, which exists between the petrous and squamous portions ; lastly, the tympanum 
 may be opened from its lower M^all, by breaking down the osseous plate of the auditory 
 meatus. 
 
 In order to show all the parts contained in the cavity of the tjTnpanum, several speci- 
 mens should be prepared in different ways. It is of importance, moreover, to study the 
 ear in the temporal bones of the adult subject and the fcetus, as well in macerated speci- 
 mens as in such as have been dried without previous maceration. 
 
 The tympanum, tympanic cavity, or drum of the ear {tympanum, a drum, d, fig. 251), is 
 a cavity situated between the external auditory meatus (b) and the labyrinth or interned 
 ear (/) ; it communicates with the pharynx, and, consequently, with the air-passages, 
 by means of the Eustachian tube (e, fig. 255) ; it is prolonged into the mastoid process, 
 by means of the mastoid cells (c), and it is traversed by a chain of small bones (1, 2, 3), 
 neuned the ossicula audittis. 
 
 The tympanum is placed in the anterior part of the base of the petrous portion of the 
 temporal bone, above the osseous lamina of the external meatus, and in firont of the 
 mastoid process ; it is directly continuous with the osseous portion of the Eustachian 
 tube, of which it seems only to be a dilatation. 
 
 From its form, which is otherwise irregular, or, rather, from the two dry membranes 
 formed upon its opposite walls, it has been compared to a military drum ; it is flattened 
 from without inward, so that its transverse diameter is the shortest. It presents for our 
 consideration an internal and an external wall, and a circumference. 
 
 The External Wall of the Tympanum. — This wall is formed by the membrana tympani, 
 and by that portion of the temporal bone in which the membrane is fitted. This portion 
 of the temporal bone is a compact lamina, which is flat in the human subject, but ex 
 tremely prominent in some animals. 
 
 The membrana tympani {c,fig. 251) is a nearly circular, semi-transparent membranous 
 septum, dry-looking like parchment, and vibratile ; it is situated between the external 
 
 * [The ceruminous glands consist of a long- conToluted tube, closed at one end, and opening by the other 
 upon the internal surface of the meatus.] 
 
NEUROLOGY. 
 
 auditory meatus, at the bottom of which it may be seen in the living subject, and the 
 cavity of the tympanum. It is directed very obliquely downward and inward ; so that, 
 instead of passing perpendicularly across the auditory meatus, it is continuous, at a 
 very slight angle, with the upper wall of that canal. In consequence of this obliquity, 
 the membrana tympani unites with the lower waU of the meatus at an angle of about 45°, 
 and the meatus itself terminates in such a manner that its lower wall is much longer 
 than the upper. 
 
 The external surface of the membrana t)mipani is free, and is directed downward and 
 outward ; the internal surface is turned upward and inward, and adheres very firmly to 
 the handle of the bone of the ear, called the malleus, by which it is drawn inward, so 
 that its centre presents a funnel-shaped depression, which is concave externally and 
 convex within. The circumference of the membrane is fitted, like a watch-glass, into a 
 circular furrow formed at the inner end of the external meatus in the adult, and into the 
 tympanic ring in the foetus. Above and behind, near its insertion into its bony frame, the 
 membrana tympani is elevated by a small process (the short process) of the malleus. 
 
 Immediately on the inner side of the insertion of the membrana tympani, opposite the 
 posterior extremity of a line drawn across its middle, is situated a small foramen, the 
 orifice of a canal which transmits the chorda tympani nerve. 
 
 Is the membrana tympani perforated 1 Some anatomists have asserted that there is 
 an aperture between the membrane and the bone, at one point of its circumference ; and 
 others have believed that an oblique slit traverses the membrane. But these perfora- 
 tions do not exist in the natural state ; so that the membrana tympani forms a complete 
 septum between the tympanum and the external auditory meatus. 
 
 Notwithstanding its tenuity and transparency, the membrana tympani consists of three 
 very distinct layers. The external or epidermic layer is a prolongation of the epidermic 
 portion only of the skin which lines the external meatus. 
 
 The internal or mucous layer is a prolongation of the extremely thin mucous mem- 
 brane which lines the tympanum. The handle of the malleus is situated between this 
 and the middle layer. 
 
 The middle or proper layer, on which the strength of the membrane depends, appears 
 to be of a fibrous nature. According to Sir Everard Home, it is muscular ; he states 
 that he distinctly saw muscular fibres radiating from the centre to the circumference, 
 first in the elephant, and afterward in the ox, and in the human subject.* 
 
 By fine injections some very delicate vessels are demonstrated in the membrane. 
 The network represented by Scemmering, who only injected the arteries, is not nearly 
 so dense as that which may be displayed by filling the veins. If a blue injection be 
 thrown into the jugular vein of the foetus, the whole membrane will become of that col- 
 our, and will present an exceedingly fine vascular network under a lens. In a new-born 
 infant, which had died with inflammation of the tympanum, the membrane was found 
 quite red. The bloodvessels appear to be situated entirely in the internal layer ; they 
 run from the circumference towards the centre of the membrane ; and this arrangement 
 has probably led to the supposition of the existence of radiated muscular fibres. 
 
 The use of the membrana tympani is to transmit the sonorous vibrations received 
 through the external auditory meatus to the air contained within the tympanum, and to 
 the ossicula of the ear. Its obliquity, besides increasing the dimensions of this vibratile 
 membrane, has certainly some use in the reflection of sonorous vibrations. As it ad- 
 heres to one of the chains of small bones of the ear, it is influenced by their movements ; 
 
 and in this way it maybe either stretched or relaxed. 
 
 The Internal Wall of the Tympanum. — The inter- 
 nal wall of the tympanum {figs. 254, 255), which is 
 perfectly exposed when that cavity is opened from its 
 external wall, presents a great number of objects for 
 our consideration. At its upper part is situated the 
 fenestra ovalis if, fig. 254), the long diameter of which 
 is directed transversely, but rather obliquely down- 
 ward and forward ; the upper border of this fenestra 
 if, fig. 258) is semi-elliptical, while the lower border 
 is straight, or, rather, it projects somewhat into the 
 opening. The fenestra ovalis, called also the vestib- 
 ular orifice of the tympanum, would establish a free 
 communication between the tympanum and the ves- 
 tibule if it were not closed by the base of the stapes 
 {d,fig. 255 ; n,fig. 257), which is accurately fitted to it. 
 
 The fenestra ovalis is placed at the bottom of a 
 depression, which is named the fossette of the fe- 
 nestra, and the depth of which depends upon the de- 
 
 * Philosopliical Transactions, p. 23, 1823. To his paper are 
 annexed three plates, representing the membrana tympani in the 
 elephant, the ox, and man. 
 
 tig. 254. 
 
 Natural size. 
 (Section of the tympanam.) 
 
THE TYMPANUM. 
 
 671 
 
 gree of projection of the aqueduct of Fallopius, which bounds it in front, by that of the 
 promontory, which is below, and by an osseous tongue which passes up to the pyramid 
 behind. 
 
 Below the fenestra ovalis is the promontory (r, figs. 254, 255), an eminence which 
 corresponds to the first turn of the cochlea, and has three grooves upon its surface, 
 that diverge above and converge below, where they terminate in a common canal, 
 which opens upon the lower surface of the petrous portion of the temporal bone, be- 
 tween the carotid canal and the groove for the internal jugular vein. This canal (ca- 
 nalis tympanicus, Arnold) may be called the canal ofJacobson, because it contains Jacob- 
 son's nerve, a branch given off from the glosso-pharyngeal, which establishes a very re- 
 markable anastomosis between the glosso-pharyngeal and the nervi molles derived from 
 the vidian and great sympathetic nerves.* The furrows upon the promontory are in- 
 tended to lodge this anastomosis. They are often formed into complete canals. 
 
 Behind the fenestra ovalis, and opposite its transverse diameter, is a small projection 
 of variable size, called the pyramid {t,figs. 254, 255). There is an opening upon it which 
 is distinctly visible to the naked eye, and makes the p)Tamid appear tubular. From thia 
 opening emerges a small cord (o, fig. 255), the nature of which is not known, but which 
 is called the stapedius muscle. A bristle passed into this opening enters the canal of the 
 pyramid, which canal is generally described as ending in a cul-de-sac, but this is not the 
 case. M. Huguier, prosector of the faculty, has clearly demonstrated, in a series of 
 preparations, that the canal of the pyramid is a long passage, which passes backward 
 and downward below the aqueduct of Fallopius, becomes vertical like the aqueduct, is 
 separated from it only by a thin lamina of bone, communicates with it by a small open- 
 ing, and at length abandons it below, to open upon the inferior surface of the petrous 
 bone, on the inner side of the stylo-mastoid foramen, at a variable distance from it. 
 Sometimes this canal bifurcates below ; so that two bristles introduced into the small 
 openings near the stylo-mastoid foramen will both enter the canal of the pyramid. A 
 small, very short, and horizontal passage, which terminates in the diploe of the tem- 
 poral bone, may be regarded as a diverticulum of this canal. 
 
 I have already stated that a fibrous-looking cord, named the stapedius muscle, emerges 
 from the canal of the pyramid. It is not yet known what structures are transmitted 
 through the divisions of this canal. 
 
 Below the fenestra ovalis, and behind the promontory, is situated the fenestra rotunda 
 (*, figs. 254, 255) ; it is placed at the bottom of a funnel-shaped depression, which was 
 well described by M. Ribes as the fossa of the fenestra rotunda, at the bottom of which 
 is found a partly membranous and partly osseous lamina, which is the commencement 
 of the spiral septum of the cochlea. In a dry bone, which has been previously macerated, 
 the membranous part being destroyed, the fossa of the fenestra rotunda communicates 
 with the vestibule. Below this compound lamina, i. e., at the lower part of the fossa 
 just described, is found the fenestra rotunda (*, fig. 257) properly so called, which leads 
 into the tympanic scala of the cochlea (l) ; whence the term cochlear orifice of the tym- 
 panum is applied to the fenestra rotunda, in contradistinction to the term vestibular orifice, 
 which is given to the fenestra ovalis. 
 
 The fenestra rotunda is closed, in the fresh state, by a membrane called the secondary 
 membrana tympani, which is said to be composed of three layers — a middle layer, an 
 external or tympanic, and an internal or cochlear layer. The two last named are mucous 
 membranes.} 
 
 Under the pyramid, and behind the fenestra rotun- 
 da, is seen a deep fossa, the sub-pyramidal fossa {v,fig, 
 254), remarkable for its constancy, and pierced by 
 several foramina at the bottom. 
 
 Upon the internal wall of the tympanum, in front 
 of the fenestra ovalis, somewhat above the trans- 
 verse diameter of that opening, and under the prom- 
 inence of the aqueduct of Fallopius, is the internal 
 orifice (n, figs. 254, 255) of the canal (m) for the internal "\ 
 muscle of the malleus, or tensor tympani muscle. This 
 orifice is wide and cup-shaped, and is supported by a 
 hollow eminence (z, jQ. 254), which is itself sustain- 
 ed by several ridges ; so that there is the greatest 
 analogy between it and the hollow projection consti- 
 tuting the pyramid. Both of them transmit a tendon. 
 One is situated in front, and the other behind the fe- 
 nestra ovalis. M. Huguier, who has paid much at- 
 tention to this subject, has shown that the cochleari- 
 
 * This can be clearly seen in some preparations in the museum 
 of the Faculty at Paris. 
 
 + [The internal or cochlear layer is merely apart of the common 
 lining membrane of the labyrinth, and is, most probably, a. fibre- Natural size. 
 
 lerous membrane, see p. 681.] (Section of the tympanum.) 
 
 Fig. 255. 
 
NEURO1.0GY. 
 
 form, process of anatomists (n, fig. 255) is nothing more than the remnant of the hollow 
 projection (x, fig. 254) just described, one half of which is very thin and fragile, and is 
 sometimes destroyed by long-continued maceration. The so-called cochleariform pro- 
 cess, therefore, is merely the reflected canal for the internal muscle of the malleus. 
 
 The Circumference of the Tympanum. — We shall examine this circumference above, be- 
 low, in front, and behind. 
 
 Above, the tympanum corresponds to the projection formed on the anterior part of the 
 base of the petrous portion of the temporal bone. In it there is formed a recess, which 
 may be named the recess of the tympanum, and which is intended for the reception of the 
 head of the malleus {\,fig. 255), and the body and posterior ramus of the incus (2). It 
 is thin and spongy, and is separated from the squamous portion of the temporal bone 
 by a suture, which persists even to the most advanced age. This suture is traversed by a 
 great number of canals, through which communicating vessels pass from those of the 
 dura mater to those of the tympanum. 
 
 Below, the tympanum is very narrow, and has the form of a trench, in which there is 
 nothing particular to notice. The wall of the tympanum is here formed by the osseous 
 lamina of the external meatus. 
 
 At the upper and back part of the circumference of the tympanum is situated a large 
 opening which leads into the mastoid cells (c c, figs. 254, 255). 
 
 These cells are extremely numerous, and of very unequal size ; they occupy the whole 
 of the mastoid portion, and the adjacent parts of the petrous portion of the temporal 
 bone, and are prolonged even above the external meatus. We may therefore regard 
 the mastoid portion of the temporal bone as an appendage to the tympanum. The mas- 
 toid cells have a very regular arrangement in the ox and horse, in which animals they 
 are disposed in a series radiating from the surface of the mastoid process towards the 
 tympanum ; their arrangement is much more irregular in the human subject. Two large 
 cells are almost always found, one near the apex, and the other at the posterior border 
 of the mastoid process. In one case I found the whole mastoid process forming a single 
 large cell, having extremely thin parietes. 
 
 The mastoid cells are lined with a very delicate fibro-mucous membrane, which is con- 
 tinuous with the mucous membrane of the tympanum. They contain air, and it is only 
 in some cases of disease that any quantity of mucus is found in them. 
 
 The mastoid cells represent, in the auditory apparatus, the cells and sinuses which 
 are connected with the organ of smell. It may be easily conceived that the intensity of 
 sounds may be increased by being reverberated from so considerable a surface. 
 
 In the foetus there are no mastoid cells ; but there exists instead, in the base of the 
 petrous portion of the temporal bone, a cavity prolonged from the recess already de- 
 scribed in the upper wall of the tympanum, for the ossicula of the ear. 
 
 In front, the tympanum is contracted like a funnel, to become continuous with the 
 Eustachian tube (c, fig. 255) ; it might even be said that the tympanum and the Eustachian 
 tube form together a single funnel-shaped cavity, the expanded portion of which is con- 
 stituted by the tympanum, and the contracted portion by the tube of Eustachius. 
 
 The canal for the internal muscle of the malleus is formed in the upper wall of the Eu- 
 stachian tube ; it is a narrow tubular canal (m), which, having reached the anterior part 
 of the tympanum, becomes applied to the internal wall of that cavity ; it passes horizon- 
 tally backward, forming a projection upon this wall, and is then reflected outward, at a 
 right angle, to form the hollow eminence already described. This canal is separated 
 only by a very thin osseous lamina from the Eustachian tube ; so that the two passages, 
 placed one above the other, have some resemblance to a double-barrelled gun. 
 
 The Eustachian Tube. 
 
 The Eustachian tube (more correctly called the Eustachian trumpet, from tuba, a 
 trumpet, e,fig. 255), or the guttural meatus of the ear, is a straight, funnel-shaped canal, 
 flattened upon its outer side, and about two inches in length ; it extends from the tym- 
 panum to the upper and lateral part of the pharynx, where it terminates by a free, ex- 
 panded extremity (wi, fig. 234), directed inward and downward, named the guttural orifice, 
 or the mouth of the Eustachian tube. This orifice is wide and dilatable, of an oval shape, 
 the larger end of the ovoid being turned upward, and being exceedingly dilatable ; but 
 beyond its mouth the tube almost immediately contracts, and will scarcely admit an or- 
 dinary probe. It continues narrow as far as its tympanic orifice, where it again becomes 
 sensibly dUated. It is directed obliquely inward, forward, and downward ; hence the 
 facility with which the mucus of the tympanum flows into the back of the throat. 
 
 The Eustachian tube consists of an osseous portion and of a cartilaginous and fibrous 
 portion. 
 
 The osseous portion, which is about seven or eight lines in length, is situated at the re- 
 treating angle formed between the squamous and petrous portions of the temporal bone 
 
 A triangular cartilaginous plate, formed into a groove, constitutes the inner half of the 
 tube ; a fibrous layer, which is at first applied against the circumfiexus palati muscle, and 
 is then lodged in the groove between the petrous portion of the temporal bone and the 
 
THE OSSICULJlf^OP THE EAR. 673 
 
 posterior border of the sphenoid, forms the external wall of the canal, which is habitu- 
 ally collapsed. The base of the triangular cartilage, which forms the guttural orifice of 
 the tube, is notched in the middle, and terminates in two thickened elongated angles ; of 
 these, the posterior one, which is more distinct, is movable, and may be pushed upward 
 and backward. The anterior angle is firmly fixed to the posterior margin of the ptery- 
 goid process. As catheterism and injection of the Eustachian tube have become com- 
 mon operations in treating diseases of the ear, it is of importance to define the exact 
 position of its guttural orifice ; it is situated (m, fig. 234) upon the side of the pharynx, 
 immediately behind, and a little above the inferior turbinated bone. 
 
 The mucous membrane •w\imY\. lines the Eustachian tube is thin, but at the mouth of the 
 tube it assumes the characters of the mucous membrane of the pharynx and of the pitui 
 tary membrane, with both of which it is continuous ; it is also continuous with the mu- 
 cous membrane of the tympanum ; hence the close sympathy which exists between the 
 lining membrane of these several parts.* 
 
 The use of the Eustachian tube is to renew the air contained within the tympanum , 
 but it also gives exit to the mucous secretion of that cavity, t 
 
 Besides the orifice of the Eustachian tube, and that of the canal for the internal mus- 
 cle of the malleus, the anterior funnel-shaped part of the circumference of the tympanum 
 presents two orifices placed one above the other : the uppermost of these is the internal 
 orifice of the canal for the chorda tympani nerve ; the lower one is an oblique fissure, 
 which transmits a fibrous cord called the anterior muscle of the malleus. M. Huguier has 
 shown me a number of preparations in which the chorda tympani nerve does not escape 
 through the fissure of Glasserius, but runs in a very narrow special canal, about five or 
 six lines in length, which is situated on the inner side of the Glasserian fissure, and 
 opens at the base of the scull in the retreating angle formed between the squamous and 
 petrous portions of the temporal bone, upon the outer side of the Eustachian tube, be- 
 hind the spinous process of the sphenoid, and sometimes upon that bone itself 
 
 The fissure of Glasserius, then, merely transmits a fibrous bundle, named the anterior 
 muscle of the malleus, and some small arteries and veins. 
 
 We may now describe the course of the chorda tympani nerve. 
 
 In its course this nerve passes through two canals, entering the tympanum by one, and 
 escaping from it by the other. The canal by which it enters commences at the vertical 
 portion of the aqueduct of Fallopius, in which the facial nerve is situated, passes upward 
 and forward, and opens immediately on the inner side of the posterior margin of the 
 membrana tympani, on a level with the horizontal diameter of that membrane, and al- 
 most in the groove into which it is inserted. Having entered the tympanum through 
 this canal, the chorda tympani describes a curve, having its concavity directed down- 
 ward, passfes between the handle of the malleus and the long ramus of the incus, enters 
 its proper canal upon the inner side of the fissure of Glasserius, and emerges at the point 
 already mentioned. 
 
 The Ossicula of the Ear. 
 
 The tympanum is traversed from without inwaM by an osseous chain, which describes 
 several angles, and consists of four bones articulated with each other, and extended from 
 the membrana tympani to the fenestra ovalis. These little bones, forming the links of 
 the chain, are named, from their respective shapes, the malleus, or Fig. 256. 
 
 hammer {I, fig. 256) ; the incus, or anvil (2) ; the os orbicular e, or ^ a ^ 
 
 round bone (4) ; and the stapes, or stirrup bone (3) : the os orbicu- 
 lare, however, appears to be merely a tubercle belonging to the 
 incus. 
 
 The Malleus. — The malleus {I, fig. 256) is the most anterior of the bones of the ear; 
 it is divided into a head, a neck, and a handle, and it has also two processes. 
 
 The head of the malleus (a, fig. 257) is situated in the recess of the tympanum, ir 
 front of the incus, and above the membrana tympani. It 
 is ovoid, and smooth, excepting behind and below, where 
 it is concave, in order to be articulated with the incus. 
 Soemmering has figured a small fibrous cord, which he 
 calls the proper ligament of the malleus, extending from 
 the head of this bone to the upper part of the recess of 
 the tympanum. 
 
 The head is supported by a constricted neck (b), which 
 is slightly twisted and flattened, and serves also as a 
 support for the two processes. 
 
 The handle (manubrium, c) is directed vertically, and, Magnified three diameters. 
 
 * [According to Dr. Henl6, the mucous membrane of the Eustachian tube, like that of the upper part of the 
 pharynx, is covered with a columnar ciliated epithelium ; but in the tympanum and mastoid cells the epithelium 
 is squamous, and not ciliated.] 
 
 t [The Eustachian tube, by establishing; a communication between the tympanum and the external air, en- 
 sures an equal atmospheric pressure on the two surfaces of the membrana tympani, so that the necessary con- 
 dition of that membrane, and of the ossicula auditOs, as conductors of vibrations, is not interfered with.] 
 
 4Q 
 
674 NEUROLOGY. 
 
 with the head and neck, forms a very obtuse angle, which retreats on the inner side ; 
 it is in contact with, and adheres firmly to the internal surface of the membrana tyrn- 
 pani, opposite the centre of which its rounded extremity is placed ; it therefore forms a 
 radius to the circle represented by the membrana tympani. The lower part of the handle 
 of the malleus is distinctly curved, having its concave side turned outward ; this ex- 
 plains the funnel-shaped depression upon the external surface of the centre of the mem- 
 brana tympani. 
 
 The processes of the malleus are two in number : the external, or short process {d), is 
 directed slightly outward, and rests against the upper part of the margin of the mem- 
 brana tympani, so as to make it project outward ; the other, or lo7ig process, is very 
 slender (processus gracilis of Raw, e), and is shaped like a thorn (processus spinosus) : rt 
 arises from the anterior part of the neck, enters the Glasserian fissure, and affords at- 
 tachment to a muscular or fibrous cord. I have several times found a simple ligament- 
 ous cord instead of this process. 
 
 The Incus. — This bone (2, Jig. 256) has been well compared to a bicuspid tooth, the 
 body of which would be represented by the body of the incus, and the fangs by its two 
 processes. 
 
 The body (f,fig. 257) is contained in the recess of the tympanum, behind the malleus, 
 with which it is articulated by a very concave surface, directed forward and somewhat 
 upward ; so that the articulation between the head of the malleus and the body of the 
 incus is effected by mutual reception. 
 
 Of its two rami, the superior or short one (g) is thick, conoid, and directed horizontally 
 backward : it is situated upon the S£une plane as the body, and, like it, is contained in 
 the recess of the tympanum, in which it terminates ; its extremity does not appear to 
 me to be free. 
 
 The inferior, or long ramus (h), is longer and thinner than the superior one ; it passes 
 vertically downward, parallel to the handle of the malleus, on a plane internal and some- 
 what posterior to it. Its lower portion is bent into a hook, the concavity of which is 
 turned inward ; and at its point is formed a sort of lenticular and distinctly defined tu- 
 bercle (4, fg. 256 ; i, Jig. 257), which has been regarded as a separate bone, and named 
 the OS orbiculare, or os lenticulare ; it appears to me to be merely a dependance of the in- 
 cus, with which I have always found it united, even in the foBtus. 
 
 The Stapes. — ^The stapes (3, fig. 356), which is shaped like a stirrup, extends horizon- 
 tally from the extremity of the long process of the incus to the fenestra ovalis (see Jig. 
 257), and is situated upon a lower plane than the rest of the small bones of the ear. 
 Its head presents a small articular cavity, for the reception of the orbicular tubercle 
 of the incus. Its base (n) is directed inward, and consists of a thin plate exactly corre- 
 sponding to the fenestra ovalis, which is rather accurately fiUed up by it, and to draw it 
 away from which a slight force is necessary, so that it has a greater tendency to fall 
 into the vestibule than into the cavity of the tjTnpanum. The slight obliquity of the 
 long diameter of the fenestra ovalis causes an inclination of the stapes in the same di- 
 rection. Of its two crura, or branches (fig. 256), the anterior is the shorter and straight- 
 er. Upon those surfaces of the crura which are turned towards each other there is 
 found a groove, which appears to indicate the existence of a membrane stretched be- 
 tween the crura. I have found the stapes very small, and, as it were, atrophied. In 
 one case, the two crura of the stapes were united together. 
 
 Muscles belonging to the Ossicula of the Ear. 
 
 Most modem anatomists agree with Soemmering in admitting four muscles for the 
 ossicula of the ear, viz., three belonging to the malleus, and one to the stapes. The 
 incus has no proper muscle, because it is merely an intermediate bone between the 
 malleus and the stapes. It is certain, however, that only one of these muscles has been 
 actually demonstrated, viz., the internal muscle of the malleus; but it is so easy to fall 
 into error when examining such minute objects, that I feel bound to suspend my judg- 
 ment as to the existence or non-existence of the other muscles. 
 
 The internal muscle of the malleus, or tensor membrancB tympani of Soemmering (e, fig. 
 251), is an elongated, fusiform muscle, contained within the bony canal formed in the 
 retreating angle of the temporal bone, above the Eustachian tube, with which it exactly 
 corresponds in direction. It arises from the cartilaginous portion of the tube, from the 
 adjacent part of the sphenoid bone, behind the spinous foramen, and from the bony canal 
 which forms its sheath. The fleshy fibres converge around a tendon, which appears 
 from among them, before it passes out from the bony canal. This tendon is reflected at 
 a right angle, like the canal in which it is contained, and then passes directly outward, 
 to be inserted into the anterior and superior part of the handle of the malleus, below the 
 processus gracilis of Raw. 
 
 The muscularity of the band or cord named the anterior muscle or ligament of the mal- 
 leus, or the great external muscle of Meckel, is doubted by a great number both of pres- 
 ent and former anatomists.* I have never seen anything more than a fibrous cord, which 
 
 " Fu^re autem et dudum et nuper clari viri qui de veris hujus musculi fibris carneis dubitarunt, cum 
 
THE OSSEOUS LABYRINTH. 61^ 
 
 cwmmehced at the tip of tTie processus gracilis of the malleus, traversed the glenoid fis- 
 sure, was re-enforced by other fibres arising from that fissure, and became continuous 
 with a fibrous layer arising from the spinous process of the sphenoid bone, and generally 
 regarded as the internal lateral ligament of the temporo-maxillary articulation. 
 
 The same remarks will also apply to the small external muscle of the malleus, or small 
 muscle of the malleus of Casserius. This muscle is figured by Soemmering, who says 
 that he found it exceedingly developed in one subject. All that I have clearly seen is a 
 cylindrical cord, extending from the upper part of the frame of the membrana tympani 
 to the short process of the malleus, or, rather, below it, according to the observations of 
 Scemmering {ad manubrium mallei, infra brevem ejus processum). This small muscle 
 would relax the membrana t3TTipani ; hence it has been named by Soemmering the lax- 
 ater membrance tympani. 
 
 The muscle of the stapes, or stapedius muscle (o, fig. 255), which is the smallest in the 
 body, has, since the time of Varolius, by whom it was discovered, been regarded as a 
 ligament by some anatomists ; nevertheless, it is more generally admitted to be muscu- 
 lar than that last described. It arises from some part of the interior of the pyramid, and, 
 escaping from that process, passes forward, and terminates at the back of the neck, or 
 constricted part of the head of the stapes, behind its articulation with the incus. Soem- 
 mering has not only represented its fleshy belly and its tendon, but also (see fig. 20, tab. 
 11) a filament of the facial nerve terminating in it. It is difficult to conceive that such 
 a serious mistake should have been committed by this great anatomist. I have exam- 
 ined this cord under a lens, and have never been able to discover any muscular fibres in 
 it. We do not conceive how a muscle should exist in so delicate a cord. Supposing, 
 however, that it does exist, it must move the stapes in such a way that the posterior ex- 
 tremity of the base of that bone would be pushed into the fenestra ovalis, while the an- 
 terior extremity would be carried outward. 
 
 Movements of the Ossicula. — The chain of small bones in the ear is so arranged, that 
 any movement of one of its extremities is communicated to the entire chain. Their mo- 
 tion is precisely similar to that of a bell-crank. M. Huguier is incUned to believe that 
 the processus gracilis of Raw serves as a fulcrum, around which the malleus performs 
 a rotatory movement, the effects of which are transmitted to the stapes through the in- 
 cus. The contraction of the internal muscle of the malleus, or tensor membranae tym- 
 pani, must draw the handle of the malleus inward and its head outward ; the incus, from 
 its firm connexion with the head of the malleus, follows that bone, and as it swings upon 
 its short horizontal process, its vertical process is carried inward, and therefore presses 
 the stapes into the fenestra ovalis. 
 
 The Lining Membrane of the Tympanum. 
 
 The tympanum is lined by a very thin membrane, which not only covers the walls of 
 this cavity, but also forms a very evident investment for the ossicula, and is, moreover, 
 prolonged into the mastoid cells, lining them throughout, and forming small duplicatures 
 around the vessels by which some of the cells are traversed. This membrane is con- 
 tinuous with the mucQus membrane of the Eustachian tube, and therefore indirectly 
 with that of the pharynx.* 
 
 It serves at once as an internal lining for the tympanum, and a periosteum for the os- 
 seous walls of that cavity, and should therefore be regarded as a fibro-mucous membrane. 
 It secretes a mucus, which in the natural state simply moistens its surface, but in some 
 cases of disease occupies the whole cavity. The catarrhal character of the products ol 
 suppuration in the tympanum, the continuity of this lining membrane with the mucous 
 membrane of the pharynx, and its extreme vascularity, leave no doubt of its being a mu 
 cous membrane. 
 
 The Internal Ear, or Labyrinth. 
 The internal ear, or labyrinth (f,fig. 251), the deep-rooted and essential portion of the 
 organ of hearing, is situated on the inner side of the tympanum, in the substance of the 
 petrous portion of the temporal bone. It consists of the osseous labyrinth, which forms 
 a receptacle for the membranmis labyrinth, which is the immediate seat of the sense of 
 hearing. No part of the body has a more conlplex and delicate structure. The labyr 
 inth is composed of three very distinct compartments, which have been named the ves 
 tibule, the semicircular canals, and the cochlea. 
 
 The Osseous Labyrinth. 
 Preparation. — This is justly regarded as one of the most difficult dissections, even 
 when the parts are previously known. The dissection should be made upon temporal 
 bones from subjects of different ages, upon bones that have been macerated, upon oth- 
 ers that have been dried without maceration, and also upon bones in the fresh state. 
 
 inultam quidem membranam a periosteo propa^atam, sulcuin maxillje repleri viderent, et processui longissimo 
 circumnasci, esEterum in eo carneam naturam non deprehenderent. Neque mea erperimenta remexpediunt 
 Musculum quoties volui, ostendi, num veras fibras viderem, plerumqiie dub^us hxsi."— (Holier, torn, v , lib 
 TV., p. 218.) ■ ■ * See note, p. 673. 
 
676 
 
 NEUROLOGY. 
 
 Commence with a foetal temporal bone, in which the labyrinth can very easily be isola- 
 ted, in consequence of its being surrounded only by a spongy texture, readily yielding to 
 the knife. In the adult, the labyrinth is, in proportion, much less developed than in the 
 foetus, and is surrounded with so compact a tissue, that, in order to cut it, it is necessa- 
 ry to use a chisel, a file, or a very strong scalpel. It is important to have a great num- 
 ber of temporal bones, so as to be able to make several different sections. 
 
 Preparation of the Vestibule. — Open the vestibule through its upper wall, which corre- 
 sponds to the upper surface of the petrous portion of the temporal bone, opposite the fe- 
 nestra ovalis, between the superior vertical semicircular canal and the internal auditory 
 meatus. 
 
 Preparation of the Semicircular Canals. — In the foetus, one of the semicircular canals 
 projects upon the base of the petrous portion of the temporal bone ; it is easy to isolate 
 it, as well as the other canals, by removing, with a strong scalpel, the spongy tissue in 
 which they are imbedded. It is useful to have two preparations of the semicircular ca- 
 nals ; one in which the canals remain entire, and another in which they have been opened. 
 
 Preparation of the Cochlea. — Remove layer by layer that part of the petrous portion of 
 the temporal bone which corresponds to the bottom of the internal auditory meatus. A 
 layer of very thin spongy tissue shows, in the foetus, that we have arrived at the coch- 
 lea ; remove this spongy tissue with care, and expose the cochlea, both on its upper and 
 lower surfaces. In one preparation, the cochlea should be merely isolated ; in another, 
 it should be carefully opened, and for this purpose it is sufficient to make a simple cut 
 into each of its turns : it is of importance not to remove the summit of the cochlea. 
 
 The Vestibule. 
 If a probe be passed from the tympanum through the fenestra ovalis {f,fig. 258), it 
 P^ 25g enters an ovoid cavity (a b t, fig. 259) called the 
 
 vestibule. 
 
 The vestible is the centre of the internal ear, 
 and forms an intermediate cavity or passage (fo- 
 rum fodinaj metallicas, Vesalius) between the 
 semicircular canals {op q,fig. 258), which are on 
 its outer side, and the cochlea (Z), which is to its 
 inner side. It is situated in a line with the axis 
 P^ of the internal auditory meatus. It is remark- 
 able for having a great number of both large and 
 small openings into it. 
 The large openings are seven in number: the first is the fenestra ovalis {ffigs. 258, 
 261), which would establish a free communication between the vestibule of the tympa- 
 num if it were not for the base of the stapes, which closes it hermetically, as we may 
 be convinced by examining it from the vestibule, when the stapes remains in its plac ♦ 
 There are five openings (o' p' q',fig. 259 ; o' a', fig. 261) for the three semicircular canals ; 
 yi„. 259. and the seventh is the orifice (/) of the vestibular 
 
 scala of the cochlea. In macerated bones we 
 find, besides, an eighth opening, situated below 
 the fenestra ovalis, having an oblong shape, and 
 leading into the highest part of the fenestra ro- 
 tunda. 
 
 Of the small openings, the first is the orifice (r, 
 fig. 259) of the aqueduct of the vestibule, which 
 opens upon the posterior wall of this cavity to 
 the inner side of the common opening for the two 
 
 „ , ^. .V ..V w. ,, vertical semicircular canals (i. e., in the recessus 
 
 ^XgJ^^'Co-iumeTer,"'" sulciformis). The aqueduct of the vestibule turns 
 
 a short distance around that common opening, and then, bending at a right angle, ter- 
 minates upon the posterior surface of the petrous portion of the temporal bone by an 
 orifice already described (see Osteology). The other small openmgs m the vestibule 
 are foramina for the passage of vessels and nerves ; they form the macula cribrosa, which 
 corresponds with the bottom of the internal auditory meatus. 
 
 The character of the vestibule is irregularly ovoid, and is divided by a cn»ta into two 
 fossae : one inferior and hemispherical, named the fovea hemispherica {a, fig. 259) ; the 
 other, superior and semi-elliptical, called the fovea semi-elliptica (h). Morgagni has de- 
 scribed a third groove-like fossa {recessus sulciformis), situated at the mouth of the com- 
 mon orifice of the two superior semicircular canals. 
 
 The Semicircular Canals. 
 The semicircular canals, three in number, represent three cylinders or tubes (tubaeformes 
 canales, Simmering), of equal diameters, and curved very regularly, so as to describe 
 
 * CThe base of the stapes is retained in its situation, and the complete closure of the fenestra ovalis is ef- 
 fected, by the reflection of the lining membrane of the tympanum on the one hand, and by that of the bning 
 membrane of the labyrinth on the other.] 
 
THE COCHLEA. 677 
 
 portions of circles ; they are situated within the substance of the base of the petrous 
 portion of the temporal bone, behind the vestibule, into which they open by the five ori- 
 fices already described. 
 
 They have been named the great, the middle, and the small semicircular canals ; terms 
 which have caused much confusion, because the differences between them, in regard to 
 length, are not alone sufficient to distinguish them from each other. 
 
 Their direction forms a much better ground of distinction between them. Two are 
 vertical, and one is horizontal : there is an anterior and superior vertical, and a posterior 
 and inferior vertical canal ; the horizontal canal is external, and is situated between the 
 two others. , . ^ 
 
 Tlie superior vertical canal (p, figs. 258, 260), which describes two thirds of a circle, is 
 placed at the highest part of the labyrinth, immediately to the outer side of the vestibule. 
 A plane passing through the two branches of this canal would cut the base of the petrous 
 portion almost at a right angle. 
 
 The convexity of this canal is turned upward, and its concavity downward. In the 
 foetus, its concavity is free, so that it can be seen without any dissection ; but in the 
 adult it is filled up with osseous tissue. 
 
 The anterior and outer extremity {f,figs. 258, 259) of this canal is dilated into an 
 ampulla, and opens separately at the upper and outer part of the vestibule. The poste- 
 rior and inner extremity unites with the corresponding extremity of the inferior vertical 
 canal to form a common canal (a, fig. 260), which opens without any dilatation into the 
 upper and inner part of the vestibule {a', fig. 261). Fig. 260 
 
 The inferior vertical canal {q, figs. 258, 260) is 
 placed at right angles to the preceding, and par- 
 allel with the posterior surface of the petrous 
 portion. It commences at the inner and upper 
 part of the vestibule, by the common canal (a, 
 fig. 260) already described, passes almost di- 
 rectly outward, curves at first downward, and 
 then forward, and becomes dilated into an am- 
 pulla {q', fig. 258) near the vestibule, into which 
 cavity it opens {q', fig. 259), about the distance 
 of a line from the point at which it commences. 
 This canal, therefore, describes nearly a com- 
 plete circle ; and hence the term canalis major 
 et longior, still given to it by Soemmering, in 
 contradistinction to the superior vertical semi- 
 circular canal, which he calls minor et brevior. 
 
 The horizontal canal (o, figs. 258, 260), canalis 
 minimus, brevissimus, sive exterior of Soemmer- fc;*^ji_ 
 ing, commences in the vestibule {o',figs. 258, 
 259) between the fenestra ovalis, which is be- 
 low, and the ampullar opening of the superior vertical canal, which is ahove ; it becomes 
 dilated into an ampulla, describes a horizontal curve having its convexity turned out- 
 ward, and opens {o',fig. 261) upon the inner wall of the vestibule, between the common 
 opening (a') of the two vertical canals and the proper opening ({'') of the inferior vertical 
 canal. 
 
 It appears, then, that each of the three semicircular canals has one of its extremities 
 dilated into an ampulla, and the other not dilated ; that the two vertical canals unite by 
 their non-dilated extremities ; that of the five openings belonging to the semicircular 
 canals, two occupy the outer, and three the inner wall of the vestibule, and that the three 
 last consist of the common canal formed by the two vertical canals, by the ampullar ex- 
 tremity of the posterior vertical canal, and by the non-ampuUar extremity of the horizon- 
 t£il canal. 
 
 The Cochlea. 
 
 The cochlea {I, fig. 258), or snail, so called from its resemblance to the shell of that 
 molluscous animal, may be said to consist of a conoid tube, which is subdivided into 
 two cavities, called scales, by a septum extending from its base to its apex, and is coiled 
 upon itself into a spiral containing two turns and a half 
 
 The cochlea is the most anterior part of the internal ear ; it is situated on the inner 
 side, and in front of the tympanum ; its base {d, fig. 260) rests upon the bottom of the 
 internal auditory meatus.* 
 
 Its external surface is blended, in the adult, with the substance of the petrous portion 
 of the temporal bone, so that it requires much skill to carve it out vnthout breaking into 
 its cavity : in the foetus, on the contrary, such a dissection is extremely easy, on ac- 
 count of the thin layer of spongy osseous tissue by which it is separated from the rest 
 of the bone. 
 
 * [The summit of the cochlea is directed forward, downward, and outward. The gyri of the cochlea are 
 soiled in a direction from below upward, a"' ''""ti without inward.] 
 
C78 
 
 NEUROLOGY. 
 
 The following parts of the cochlea are separately described : the tube of the cochlea or 
 lamina gyrorum, the lamina spiralis, the axis or columella, the two scala, and the aqueduct. 
 The Tube of the Cochlea. — The tube of the cochlea {canalis spiralis cochlce, or lamina gy- 
 rorum) is the compact lamina (l, figs. 258, 262) which forms the external walls of the 
 cochlea. If we imagine a hollow osseous cone, coiled spirally, cicut circa fulcrum convol- 
 vulus {Holler), or like a winding staircase ; and farther, that the lowest turn of the spire 
 embraces the turn above it, and that the walls of the different turns are blended with 
 each other, we shall have a correct idea of the tube of the cochlea : as before stated, the 
 spire thus formed describes two turns and a half 
 
 The Spiral Lamina of the Cochlea. — The spiral canal, or tube of the cochlea, is subdi- 
 vided lengthwise into two secondary cavities (c e, c e, figs. 263, 264), called scala. {scala, a 
 staircase), by a septum (a), which is named the spiral lamina of the cochlea {lamina spi- 
 ralis cochlea). 
 
 Commencing at the base of the cochlea {t, fig. 259 ; also fig. 263), and at the fenestra 
 rotunda, where it can be very easily seen, the spiral lamina winds edgewise around the 
 axis or columella {b b, fig. 262), and is continued without any interruption to the summit 
 or cupola (/) of the cochlea, the several turns of which it exactly follows. Its internal 
 border is applied against the axis of the cochlea, and adheres intimately to it, excepting 
 above, where it is free for a short distance, and leaves a communication {n, fig. 263) be- 
 tween the two scalae. Mar go liber lamina spiralis quo fit ut utriusque scala. sit communica- 
 tio {Sammering). Its external border adheres to the inner surface of the lamina gyrorum, 
 or tube of the cochlea. In consequence of the conical form of this tube, the lamina spi- 
 ralis would, if unrolled, represent an isosceles triangle, the base of which had corre- 
 sponded to the fenestra rotunda, and the apex to the summit of the cochlea. 
 
 The spiral lamina consists of two portions — an internal osseous and an external mem- 
 branous portion.* 
 
 The osseous portion {lamina spiralis ossea, d, figs. 259, 261, 262, 264) predominates in 
 the first turn, diminishes gradually in the second, and 
 ceases at the commencement of the third, where it termi- 
 nates in a kind of hook or beak {hamulus vel rostrum, e,fig. 
 262). This bony portion is thick, and consists of two la- 
 mellae, between which are found a great number of very 
 delicate canals, through which the nerves of the cochlea 
 v pass. These two lamellae form two distinct furrows upon 
 1^' the columella. 
 
 The membranous portion {lamina spiralis membranacea, 
 a a, figs. 263 to 265) completes the septum, forming its 
 Cochlea (dry) magnified four times. ^y^gj. ^^^ J^ jg narrow in the first tum of the cochlea, 
 
 becomes broader in the second, and constitutes the entire septum in the third 
 
 Fig. 263. 
 
 Cochlea ( 
 
 The bony and membranous portions of the spiral lamina, 
 therefore, represent two isosceles triangles, so arranged 
 that the base of the one corresponds to the apex of the 
 other, and vice versa. 
 
 Moreover, as Comparetti remarks, three zones can be 
 distinguished in the membranous portion of the spiral lam- 
 ina, the consistence of which diminishes progressively 
 ■/ from the margin of the osseous lamina towards the inter- 
 nal surface of the tube of the cochlea. 
 
 The Axis or Columella of the Cochlea. — From the bottom, or, 
 rather, from the posterior part {d, fig. 260) of the bottom of 
 the internal auditory meatus, arises a bony process, which is directed almost horizontally 
 outward ; it occupies the centre or axis of the cochlea, and around it both the tube and 
 spiral lamina describe their several turns. This bony process is called the axis of the 
 cochlea, columella, modiolus, or nucleus {b, figs. 262, 264). It extends from the base to the 
 summit of the cochlea, but undergoes certain changes during its course. Opposite the 
 first turn it is extremely thick, but becomes much thinner in the first half of the second 
 tum. In the second half of the second turn, and in the last half turn, it is replaced by a 
 cup-shaped lamella, called the infundibulum (scyphus, Vieussens, c, fig. 262), the expand- 
 ed portion of which is turned towards the cupola (/) of the cochlea. The modiolus or 
 axis of the cochlea, then, has three perfectly distinct parts. 
 
 The base of the modiolus, which is seen at the bottom of the auditory meatus, is marked 
 by a very distinct spiral tract {d, fig. 260), perforated with foramina, through which the 
 filaments of the auditory nerve are transmitted. It is the tractus spiralis foraminulentus 
 of Cotugno. 
 
 The apex of the modiolus, when examined in a cochlea which has been opened from 
 the under surface of the petrous portion of the temporal bone, presents a decidedly in- 
 fundibuliform figure. But in a cochlea which has been opened from its upper surface 
 
 * [In the dried cochlea [fig. 262), the two seals communicate along their whole course.] 
 
THE COCHLEA. 679 
 
 ifig. 264), on the contrary, it has the appearance of a very slender stalk, continuous with 
 the rest of the modiolus, and proceeding directly to the cupola of the cochlea. This two- 
 fold structure depends upon the fact that the terminal lamella of the modiolus forms only 
 half a funnel, which half is turned towards the lower half of the cochlea. , This terminal 
 lamella of the modiolus, which has been very well described by Huguier, is of a triangular 
 form, extends through half a turn of a spiral, and adheres to the inner surface of the 
 tube of the cochlea by its external convex border. Its internal border or margin is straight 
 and free, and is the only part of this lamella which is seen when the cochlea is opened 
 from above, while its convex border and its surfaces are distinctly seen when the coch- 
 lea is opened from below. The hamulus (e, fig. 262) of the osseous portion of the lamina 
 spirahs terminates opposite the middle of this free border or margin. 
 
 The surface of the modiolus is marked like a screw by two furrows correspondmg 
 to the two lamellae of the osseous part of the spiral lamina ; this surface is pierced with 
 foramina for the branches of the auditory nerve. 
 
 If the modiolus be divided longitudinally (fig. 264), it wDl be seen that its centre is 
 traversed by a number of canals, for the passage of the branches pig. 264. 
 
 of the auditory nerve. These canals open by the foramina on 
 its surface. In the centre of the half funnel formed by the ter- 
 milial lamella of the modiolus is an opening, through which the 
 terminal filament of the cochlear branch of the auditory nerve 
 passes out ; it is the orifice of the tubulus centralis modioli. 
 
 The Scarce of the Cochlea. — The spiral lamina {d d, fig. 264) di- 
 vides the cavity of the tube of tne cochlea into two secondary 
 cavities (c e, c e), called the scala of the cochlea. They are dis- 
 tinguished as the external, superior, or vestibular scaia (scala ves- 
 tibuli, c c, figs. 263, 264), and the internal, inferior, or tympanic 
 scala (scala tympani, e e). The first (c c, fig. 265) communicates ^ 
 
 directly with the vestibule (between t and s) ; the second, which Coehiea magnified. 
 
 commences at the fenestra rotunda (s, fig. 258), would communicate with the tympanum 
 if that fenestra were not closed by a membrane ; hence the term scala clausa. The 
 tympanic scala is decidedly larger than the vestibular. The section of either of the scalae, 
 at right angles to its axis, is semicircular. 
 
 The two scalae conununicate near the summit of the cochlea (at n, figs. 263, 265). Both 
 the situation and nature of this communication can be easily eiscertained, and have been 
 well described by Soenomering, and more recently by MM. Breschet and Huguier. 
 
 The lamina spirahs, which, we have seen, adheres closely to the modiolus, continues 
 to wind spirally around the half-funnel-shaped termination of the modiolus, but when it 
 arrives opposite the concavity of this half funnel, it ceases to be attached to that con- 
 cavity, its internal border becomes free, and is then continued on to the inner surface of 
 the summit of the cochlea. It follows, therefore, that the free concave border of the 
 lamina spiralis is opposite to the concavity of the infundibulum ; and hence there is an 
 interruption in the septum, in the form of a circular opening, the canalis scalarum commu- 
 nis of Cassebohm, the helicotrema of Breschet {n,figs. 263, 265), which establishes a com- 
 munication between the two scalae : moreover, this opening is not situated precisely at 
 the summit of the scalae, but a little below that point ; nor is the opening of communica- 
 tion (between t and s, fig. 265) between the vestibular scala and the vestibule situated at 
 the lowest part of that scala. 
 
 The Aqueduct of the Cochlea. — The aqueduct of the cochlea opens at one end {n,fig. 259) 
 into the tympanic scala of the cochlea, near the fenestra rotunda ; and at the other, by an 
 expanded extremity, upon the lower border of the petrous portion of the temporal bone, 
 near the jugular fossa. It does not appear to have any such use as was attributed to it 
 by Cotugno. Like the aqueduct of the vestibule, it is merely a canal for a vessel, and 
 as such was denominated by Wildberg canalis vcnosus cochlea. The liquor Cotunnii 
 could not pass through this canal, for it is closed by the dura mater. Ilg has taken a 
 very ingenious view of the structure of the modiolus and cochlea. According to that 
 author, the modiolus is not an osseous centre independent of the lamina gyrorum, but 
 rather the internal wall of the spiral tube of the cochlea, which, in describing its first 
 turn, intercepts a considerable cylindrical space of about two lines and a half in diam- 
 eter, and then a smaller, but still cylindrical space, of about half a line in diameter, in 
 its second turn ; while in the third turn there is no space, and therefore the axis or 
 modiolus is wanting, but it is replaced by the internal wall of the spiral tube of the 
 cochlea itself The terminal lamella of the modiolus would therefore be formed by the 
 internal wall of the spiral tube. 
 
 This view is supported by the structure of the bottom of the internal auditory meatus, 
 on which is found a turn and a half of a spiral groove, precisely corresponding to the 
 spire of the cochlea, and by sections of the cochlea made after Scemmering's plan, from 
 the apex to the base. {Vide figs. 11, 12, 13, 14, 15, of Scemmering's fourth plate.) 
 
 The Membranous Labyrinth. 
 
 The membranous labyrinth, discovered by Conipannti and .Scarpa, ha.s been correctly 
 
NEUROLOGY. 
 
 described and figured by Soemmering. M. Breschet has recently enriched our knowl- 
 edge of this intricate anatomical subject with many most interesting facts. {Etudes 
 anatomiques et physiologiques sur Vorgane de Vouie et sur V audition dans Vhomme et Us ani- 
 maux vertebres, 1833.) 
 
 It is useless to attempt the examination of the membranous labyrinth in the human 
 subject without some previous preparation. If the labyrinth be opened, it is found to 
 contain a fluid ; the eye can detect nothing else. By previously macerating it in diluted 
 nitric acid, the twofold advantage is gained of softening the bones, so that they can be 
 cut with a scalpel, and of hardening and rendering opaque the nervous tissues. Before 
 studying the membranous labyrinth in the human subject, it should first be examined in 
 the large cartilaginous fishes, such as the ray and the turbot, in which it is most highly 
 developed. It is then seen that the semicircular canals and the vestibule contain, be- 
 sides a fluid, certain semi-transparent membranous tubes and sacs, the aspect of which 
 closely resembles that of the retina. 
 The membranous labyrinth (fig. 265) is not so extensive as the osseous labyrinth : 
 thus, it does not enter the cochlea, and its diameter is 
 much less than that of the bony labyrinth. It scarcely 
 occupies one half the cavity of the latter. 
 
 The space between the bony and membranous lab- 
 yrinths is filled with a limpid fluid, named, after Co- 
 tugno, the liquor Cotunnii, although it had been no- 
 ticed by several anatomists before that author. (De 
 aqua ductibus auris human<B inierna. Cotugno, 1760.) 
 It is the perilymph of M. Breschet. 
 There is no air in the labyrinth, and it is somewhat 
 Membranous labyrinth (leftside). singular that SO accuratc an anatomist as M. Ribes 
 
 should have recently defended a contrary opinion, although it has been repeatedly refuted. 
 The membranous labyrinth is itself filled with a fluid which was correctly described 
 by Scarpa, and which might be named X\\e fluid of Scarpa. M. de Blainville has com- 
 pared it to the vitreous humour of the eye, and has named it la vitrinc auditive : it is the 
 endo-lymph of M. Breschet. 
 
 The membranous labyrinth consists of membranous semicircular canals, and of a ves- 
 tibular portion. 
 
 The Membranous Semicircidar Canals. 
 
 The membranous semicircular canals {op q,fig. 265) were regarded as nervous cords by 
 Scarpa, who first described them ; they have precisely the same form as the osseous 
 semicircular canals, although they do not completely fill them. Soemmering improperly 
 calls them tubuli membrano-cartilaginosi. Each membranous canal, like the corresponding 
 osseous one, has its ampulla, or ovoid muscle {o' p' q'). 
 
 The two vertical membranous canals unite at one end into a common canal, and, 
 therefijre, the three membranous semicircular canals, like their osseous investments, 
 open into the membranous vestibule by five distinct orifices. 
 
 The membranous vestibule consists of two very distinct parts, the common sinus and the 
 saccule. 
 
 The sinus communis vestibuli, or vestibular utricle (u),* as was first shown by Scarpa, 
 forms the confluence of the membranous semicircular canals which open into it by five 
 orifices. The utricle is situated in the fovea semi-elliptica of the vestibule, and floats, 
 as it were, in the liquid of Cotugno ; it is distended by the liquid of Scarpa, so as to re- 
 semble an oblong bulla. The liquid of Cotugno separates it from the base of the stapes, 
 as Scarpa very well pointed out. 
 
 The sacculus vestibuli, or vestibular saccule (sacculas proprius sphaericus, Soemmering, 
 s), is much smaller than the utricle. Its connexions with the utricle have been com- 
 pared by Fischer to those of the crystalline lens with the vitreous body : it occupies the 
 fovea hemispherica of the vestibule, and is therefore situated below the utricle. Accord- 
 ing to Soemmering, it does not adhere to the utricle ; that author has even represented a 
 small space between these two parts, t According to others, there is a communication 
 between them, and the saccule is merely a supplementary cavity to the utricle. I have 
 not yet been able to satisfy myself concerning this point. 
 
 The membranous labyrinth, then, is quite distinct from the membrane which lines the 
 labyrinthic cavities. This periosteal membrane, which analogy would lead us to regard 
 as a fibro-serous membrane, is the only membrane which is prolonged into the cochlea. 
 We might, however, regard that portion of the lamina spiralis which is next to the in- 
 ner surface of the lamina gyrorum as a portion of the membranous labyrinth. 
 
 * Alveus utriculoaiis of Scarpa, uiriculus communis of ScEmmering, Hnus midian of M. Breschet. 
 
 t Sacculus teres cum utriculo communi nuUibi cohseret, et ubi cultri apice aperitur, sphajricam ormam re- 
 tinet. (Explanation of fig. 2, pi. 3.) According to M. Breschet, the sacculus and utriculus adhere intimately, 
 and he is inclined to believe that their cavities even communicate ; but, from the extreme delicacy of tbeM 
 •tructures, he has been unable to confirm this supposition 
 
THE AUDITORY NERVE, ETC. 6S1 
 
 The Calcareous Matter of the Vestibule. — ^The examination of the ear of fishes, which 
 has proved of such assistance in investigating the structure of the human membranous 
 labyrinth, has also led to the inquiry, whether there existed anything in the human ear 
 analogous to the solid calcareous concretions found in the labyrinth of the ear of fishes. 
 From the researches of M. Breschet, it appears that the labyrinthic stones, or otolitkes, 
 of fishes, are represented in all the mammalia, and, consequently, in man, by a cretace- 
 ous powder, which he has named otoconia {ovc, uroc, the ear, and Kovig, dust) ; and that 
 this powder exists both in the utricle and the saccule, collected together into two white 
 shining masses, which were seen and described by both Comparetti and Scarpa, but 
 were mistaken by them for the dried acoustic nerve. Does it fulfil the same uses as the 
 otolithes in fishes 1 or should it be regarded as a rudimentary condition of an important 
 structure in other animals ] 
 
 The Auditory Jferve and the Vessels of the Ear, 
 
 The auditory nerve, or special nerve of the organ of hearing, is remarkable for its soft- 
 ness, and hence it has been named the portio mollis of the seventh cranial nerve. The 
 auditory nerve arises, at least in part, from the anterior wall of the fourth ventricle ; 
 having reached the bottom of the internal auditory meatus, it divides into two branches : 
 an ajiterior and larger, distributed to the cochlea, and a posterior, intended for the vesti- 
 bule and semicircular canals. The anterior or cochlear branch {t,fig. 264) has a spiral 
 arrangement, like that portion of the bottom of the auditory meatus (d,fig. 260) to which 
 it proceeds, and it enters through the foramina in the tractus spiralis of the lamina cri- 
 brosa. One set of nervous filaments enters the small canals in the centre of the modi- 
 olus {b,fig. 264) ; the others are applied to the surface of the modiolus {t,Jlg. 263) ; the 
 latter filaments spread out upon the first turn of the lamina spiralis (<, ^^. 265), radiating 
 in the most regular manner, and having arrived near the outer border of the spiral lam- 
 ina, they each divide into two or three ramuscules, which anastomose together, so as to 
 form a nervous expansion.* These radiating filaments are more distinct upon the lower 
 than upon the upper surface of the spiral lamina. 
 
 Those filaments of the nerve which are not spread out upon the first turn of the lami- 
 na spiralis pass through the foramina in the centre of the modiolus, and spread out upon 
 the second turn, in the same manner as those already described. Lastly, the highest 
 filaments emerge from the opening at the apex of the modiolus, and terminate in a sim- 
 ilar manner. It follows, therefore, that the nerves of the cochlea successively diminish 
 in length, as the spiral lamina does in width ; and thus the radiating nervous filaments 
 resemble the strings of a harp, in becoming successively shorter and shorter. It is 
 probable that this arrangement is not without its influence upon the function of hearing. 
 In a temporal bone softened by the action of nitric acid, the auditory nerve, the modi- 
 olus, the spiral lamina, and the periosteal membrane which lines the cochlea, may be 
 dissected with the greatest facility. 
 
 The posterior or vestibular division of the auditory nerve is subdivided into three 
 branches, the largest of which (v, fig. 265) is distributed to the utricle {u) and to the am- 
 pullae {o' p') of the superior vertical and horizontal membranous semicircular canals ; the 
 middle-sized branch is distributed to the sacculus (s), and the smallest ends in the am- 
 pulla (g') of the inferior vertical membranous semicircular canal, t 
 
 Bloodvessels may be traced into the membranous labyrinth ; most of them enter by 
 the internal auditory meatus ; those which belong to the cochlea pass through the fora- 
 mina in the modiolus, and are distributed in a radiating manner like the nerves 
 
 THE CEREBRO-SPINAL AXIS. 
 General Observations. 
 
 The cerebrospinal axis constitutes the central portion, while the nerves form the periph- 
 eral portion of the nervous system. 
 
 The apparatus of innervation formed by the cerebro-spinal axis and the nerves togeth- 
 er, and named the nervous system, is the most important part in the animal machine ; it 
 is the source not only of sensation and motion, but of the universal sympathy existing 
 between the several parts of the animal economy; and that part of it called the brain 
 performs the highest function allotted to organized beings, by becoming the immediate 
 instrument of the soul in the exercise of the intellectual faculties. 
 
 * [According to observations made by Treviranus, Gottsche, and others, the filaments of the cochlear nerve 
 in animals do not anastomose, but terminate in isolated extremities, which are in some cases papillary (TVe- 
 viranus), and in others club-shaped (Gottsche) ."^ 
 
 t [The nervous filaments proceeding- to the utricle and saccule form a, fan-like expansion upon those sacs, 
 per.etrate into their interior, and spread out as a nervous layer on their internal surface. EacOi of the nerves 
 which are distributed to the membranous ampullar apjiears to bifurcate, so as partially to embrace its corre- 
 sponding ampulla in a transverse direction : the nervous filaments then penetrate into the ampulla, and spread 
 out iip<m a transverse septum, formed in its interior by the folding inward of the walls of the cavity, and also 
 upon the adjacent parts of those walls. (See Steifensand, Mutter's Arch., 1835. )J 
 
 4R 
 
682 NEUROLOGY. 
 
 The cerebro-spinal axis consists of that soft, pulpy, elongated, and symmetrical mass 
 of nervous substance, which, becoming enlarged at its upper part, occupies the vertebral 
 canal and the cavity of the cranium, and forms the centre from which the nerves of all 
 parts of the body take their origin, or in which they all terminate. 
 
 The structure of no other organ in the tody excites so much curiosity, and, unfortu- 
 nately, there is none whose structure is involved in greater obscurity. Notwithstand- 
 ing the real advances that have recently been made in our knowledge of the anatomy of 
 the brain, we must still acknowledge, with Steno, that the human mind, which has car- 
 ried its investigations even into the heavens, has not yet been able to comprehend the 
 nature of the instrument by which its own operations are performed, and that its pow- 
 ers seem to abandon it as soon as it turns its attention to the organ in which it resides. 
 Until the end of the last century, the study of the central portion of the nervous system 
 consisted in a simple enumeration of its parts, or, rather, in a more or less imperfect 
 description of its external surface, and of the different objects displayed by various sec- 
 tions. The nomenclature of the different parts of the encephalon* is alone enough to 
 show with what limited views the researches of those anatomists must have been made, 
 who did not suspect that this pulpy-looking mass — a sufficient definition of which they 
 believed to be, that it held an intermediate place between the solids and the fluids of the 
 body — ^was as wonderful in the delicacy and intricacy of its structure, as in the impor- 
 tance and elevated character of its functions. In the present day, anatomists include 
 in the study of the encephalon not only the topographical study of its various constituent 
 parts, but also the determination of the mode in which those parts are connected togeth- 
 er. To ascertain this latter point, apart from all questions as to origin, formation, gen- 
 eration, and re-enforcement, with which the subject has lately been embarrassed, should 
 constitute the special aim of every inquiry into the anatomy of this part pf the nervous 
 system. 
 
 The central portion of the nervous system consists, 1. Of the spinal cord; 2. Of the tu- 
 ber annulare, the ■peduncles of the cerebrum and cerebellum, and the tubercula quadrigemina ; 
 these together constitute a very constricted portion, which forms the bond of union be- 
 tween the other parts of the encephalon, and which I shalll accordingly name le naeud de 
 I'encephale ;t 3. Of the cerebellum ; 4. Of the cerebrum. 
 
 The cerebro-spinal axis is surrounded by three membranes or coverings, called the 
 meninges (from /^^vty^, a membrane), which perform some important functions in regard 
 to it, and which must in the very first place occupy our attention. 
 
 THE MEMBRANES OF THE CEREBRO-SPINAL AXIS. 
 
 General Remarks. — The Dura Mater — the Cranial Portion, its Structure and Uses — the 
 Spinal Portion. — The Arachnoid — its Cranial Portion — its Spinal Portion — the Sub- 
 arachnoid Fluids — their Uses. — The Pia Mater — its External Cerebral Portion. 
 
 But few parts of the body are so effectually protected as the cerebro-spinal axis ; this 
 protection is afforded in part by the vertebral column,^ and by the cranium, the mechan- 
 ism of which we have already described as being so eminently calculated to defend the 
 parts situated within them. 
 
 Besides the osseous case formed by the vertebro-cranial column, we find, surrounding 
 the cerebro-spinal axis, a fibrous sheath, named the dura mater ; a serous membrane, 
 called the arachnoid ; and a proper membrane, named the pia mater, in which the vessels 
 of the nervous centre ramify. 
 
 The Duka Matee.iJ 
 
 Dissection of the Dura Mater of the Scull. — Make either a crucial incision, or one ex- 
 tending from before backward, or from ear to ear, through the integuments of the head ; 
 turn back the flaps, taking care to remove the periosteum with the hairy scalp. 
 
 The bones of the cranium being thus exposed, the scull-cap may be removed, either 
 with a sort of hatchet (marteau-hachette) or a saw. 
 
 This hatchet is the most expeditious and the best instrument. There is no fear of 
 shaking or lacerating the brain, if the instrument be properly used ; but it is almost im- 
 possible to avoid cutting the brain with the saw, the only advantage of which over the 
 other is, that it makes an even section. 
 
 The section should be carried quite round the cranium, about a finger's breadth above 
 
 * From iv, in, and Kt<pa\ii, the head ; a convenient term, used to signify that part of the cerebro-spinal axis 
 which is situated within the cranium. 
 
 t [It is necessary to bear in mind that the equivalent term, nodus encephali, has been assigned by Sccmmer- 
 ing to the pons Varolii.] 
 
 t A vertebrated animal may also be defined to be an animal provided with an encephalon ; an inter-vertebra- 
 ted animal is one having no encephalon. 
 
 ^ The application of the term mater to the meninges of the brain is derived from the Arabians, who regard- 
 ed these membranes as the origin, or mothers of all the other parts of the body ; or, perhaps, as Ilaller has ob- 
 lerved, this use of the term depends upon an Arabic idiom, by which the covering of any body whatsoever is 
 called its mother. 
 
EXTERNAL SURFACE OF THE DURA MATER. 683 
 
 the orbital arches, the scull-cap being raised and removed by means of the narrow end 
 of the hatchet, or by means of a hook attached to the extremity of its liandle. 
 
 If the brain is not to be preserved, a somewhat different method of proceeding is adopts 
 ed. Two parallel cuts must be made with the saw, one on each side of the superior lon- 
 gitudinal sinus, along its whole extent. Each of these cuts should then be met by anoth- 
 er, carried horizontally through the corresponding side of the scull. When the two por- 
 tions of bone included between these sections are removed, there remains an intermedi- 
 ate portion of bone, about an inch wide, extending from the nasal eminence to the occip- 
 ital protuberance. The dura mater should then be divided along the borders of this in- 
 termediate portion of bone, and the brain and cerebellum removed. 
 
 If, however, it be intended to preserve the brain and cerebellum, after the entire scull- 
 cap has been removed in the ordinary manner, the dura mater must be divided circularly, 
 along the cut edge of the cranium, the anterior extremity of the falx cerebri must be di- 
 vided with the scissors, and the whole fibrous cap turned backward. 
 
 Another mode, and one which I prefer, is, to make an incision through the dura mater, 
 along each side of the superior longitudinal sinus, and then to divide the anterior ex- 
 tremity of the falx, and reflect that part backward. 
 
 Dissection of the Dura Mater in the Vertebral Canal. — This part of the dura mater may 
 be exposed, either by removing the arches of the vertebrae, or by taking away the bodies 
 of these bones. The latter method is but seldom adopted. 
 
 The arches of the vertebrae may be removed by means of a chisel and mallet, or, still 
 better, by the rachitame. 
 
 An instrument has lately been invented, consisting of two parallel saws, slightly con- 
 vex on their toothed edges, firmly connected together, but capable of being separated or 
 approximated as may be desired. Preference is justly given to the rachitome over this 
 complicated instrument. The important object in opening the spine is, to make the sec- 
 tion opposite the junction of the laminae with the transverse and articular processes. 
 
 In order to display the continuity of the cranial and spinal portions of the dura mater, 
 it is necessary to connect the sections already made in the head and spine, by removing 
 with the saw the intervening portion of the occipital bone. 
 
 A beautiful preparation of the dura mater may be made by removing the roof and sides 
 of the scull, and the arches of all the vertebrae ; by then taking out the encephalon and 
 spinal cord through incisions in the dura mater, which may be readily concealed ; and 
 by filling the cavity thus left with tallow, which is afterward to be dissolved out by spir- 
 its of turpentine, or, what is easier to do, the cavity of the dura mater may be filled with 
 fine sand. 
 
 The dura mater (meninx crassa, Galen; le meninge, Chauss.) is a fibrous membrane 
 which covers and protects the cerebro-spinal axis, and the roots of all the nerves which 
 arise from or terminate in that portion of the nervous system. 
 
 It is the most external of the membranes of the brain and spinal cord (meninx exteri- 
 or, Smmmering) ; it consist of a cranial and a spinal portion. 
 
 The Cranial Portion of the Dura Mater. 
 
 The cranial portion of the dura mater forms a fibrous sac, which lines the internal sur- 
 face of the bones of the cranium, forming their internal periosteum, and at the same time 
 serves £is a covering for the encephalon, and separates its different parts by means of 
 .prolongations or incomplete septa. 
 
 The dura mater in the scuU presents for our consideration an external and an internal 
 surface. 
 
 External Surface of the Dura Mater. 
 
 Its external surface is accurately moulded upon the internal surface of the bones of the 
 cranium, to which it adheres by a multitude of small fibrous and vascular prolongations, 
 which can be readily displayed by putting the membrane under water. These prolonga- 
 tions give the external surface of the dura mater a rough appearance, which contrasts 
 strongly with the smooth aspect of its internal surface. The ramifications of the mid- 
 dle meningeal arteries and veins are seen on the external surface of the membrane, and 
 project from it, as if they were only laid upon it. 
 
 The dura mater adheres to the parieties of the cranium with different degrees of 
 firmness in different situations. 
 
 Thus, it is generally less firmly adherent to the roof of the scull than to its base, where 
 it is impossible to separate it from the bone. The upper border of the petrous portion 
 of the temporal bone, the posterior border of the lesser wings of the sphenoid, and the 
 margin of the foramen magnum, are points to which it is very firmly attached ; but the 
 dura mater adheres more strongly opposite the sutures than in any other situation. Upon 
 the orbital plates, on the occipital fossae, and upon the squamous portion of each temporal 
 bone, it adheres so slightly, that it has been conceived to be altogether unattached in 
 those regions.* 
 
 * An erroneous opinion for a long time prevailed that the adhesions between the dura mater and the hones 
 
6S4 NEUROLOGY. 
 
 The firmness of the adhesion between the dura mater and the bones varies at differ- 
 ent periods of life, and also the manner in which it is effected. Thus, in old subjects, 
 the parts are so closely united, that it is almost impossible to take off the roof of the 
 Bcull without, at the same time, removing portions of the dura mater. When this hap- 
 pens, there is ossification of the outermost layers of this membrane. In the new-born 
 infant, the adhesion is firmer than in the adult, especially opposite the sutures. 
 
 As to the mode in which this adhesion is effected, it may be stated, that in the infant 
 it appears to be exclusively by means of vessels ; in old age, almost entirely by fibrous 
 tissue ; and in the adult, by partly vascular and partly fibrous prolongations. 
 
 The dura mater is, moreover, attached to the bones of the cranium by means of the 
 fibrous canals formed by this membrane for the nerves and vessels which pass through 
 the foramina in the base of the- scull. 
 
 The most remarkable prolongations of the cranial portion of the dura mater, except- 
 ing that for the spinal cord, are those given off opposite the right and left sphenoidal 
 fissures. Each of these prolongations separates into two layers, one of which forms the 
 sheath of the corresponding optic nerve, while the other blends with the periosteum 
 lining the cavity of the orbits. 
 
 The Internal Surface of the Dura Mater. 
 
 The internal surface of the cranial portion of the dura mater appears smoothly polished, 
 and is constantly lubricated with serosity ; its polished appearance is owing to a layer 
 of arachnoid with which it is covered ; this layer is so thin that one might be disposed 
 to deny its existence, and it is so firmly united to the dura mater that its demonstration 
 is extremely difficult. Excepting at the points where the cerebral veins enter the dif- 
 ferent sinuses, the internal surface of the dura mater lined by the arachnoid is free, and 
 is in contact with the cerebral arachnoid, and indirectly with the outer surface of the 
 encephalon. 
 
 From this surface certain prolongations or imperfect septa are given off, by which the 
 cavity of the cranium is divided into several compartments. These septa are three in 
 number, viz., the falx cerebri, the tentorium ccrebelH, and the falx cerehelli. 
 
 The Falx Cerebri. — This is a fibrous lamina {d, fig. 220), which is placed vertically 
 along the median line, is shaped like a sickle, and extends from the foramen caecum to 
 the tentorium cerebelli. Its point, which is in front, dips into the foramen caecum, and 
 envelops the crista galli ; its base is behind, and rests perpendicularly upon the middle 
 of the tentorium cerebelli. The venous canal, called the straight sinus, is situated along 
 the line in which the falx and the tentorium meet. The upper border of the falx is con- 
 vex, and extends from the foramen caecum to the internal occipital protuberance. In 
 this border is placed the superior longitudinal sinus. 
 
 The lower border is concave, thin, sharp, and free, and corresponds to the corpus cal- 
 losum, touching that body, however, only at the back part, and, according to some anat- 
 omists, making a rather deep furrow upon it. This free border, which is thicker behind 
 than in front, contains within it a small vein, which has been named the inferior longi- 
 tudinal si7ius. The two surfaces of the falx correspond to the internal surfaces of the 
 two hemispheres of the brain. Not unfrequently the falx cerebri is found as if torn 
 through in some points, and I once observed the two hemispheres continuous with each 
 other through an opening in this septum. 
 
 The use of the falx is evidently to obviate the effects of lateral concussion of the 
 brain, and to prevent one hemisphere from pressing upon the other, while the person is 
 lying upon his side. 
 
 The Tentorium Cerebelli. — This is an imperfect horizontal septum (le septum trans- 
 verse, Chauss.), which is, as it were, notched in front, and which separates the cerebrum 
 from the cerebellum. It is constantly in a state of tension ; a condition which depends 
 upon the permanently tense state of the falx cerebri. These two parts, indeed, mutually 
 preserve each other's tension, and when either of them is cut, the other necessarily be- 
 comes relaxed. It is, therefore, only when the tentorium is examined in situ, and the 
 falx is left uninjured, that the anatomy of the former can be properly understood. It is 
 then seen that it represents two planes, inclined upward, and united in the middle line 
 at an obtuse angle, so as to form a sort of arch, upon the top of which the base of the 
 falx cerebri rests. The concavity of this arch corresponds to and is accurately fit ted 
 upon the convex upper surface of the cerebellum below ; the convexity corresponds to 
 the slightly concave under surface of the posterior lobes of the cerebrum. 
 
 Its outer or convex border is directed horizontally ; it corresponds behind to the posterior 
 portion of the lateral grooves, and in front to the upper border of the pars petrosa. The 
 lateral sinus occupies the whole occipital portion of this border. 
 
 Its inner or concave border is parabolic ; between it and the basilar groove, in front, a 
 small space is intercepted, which is occupied by the nodus encephali, being accurately 
 
 were the results of disease ; and it has even been believed that a space existed between the dura mater and 
 the bones of the cranium. These errors resulted from a physiological hj-pothesis, vi-hich attributed the move- 
 ments of the brain to contraction of the dura mater. 
 
STRUCTURE OP THE DURA MATER. 66S 
 
 adapted to that part of the brain. The extremities of the external and internal borders 
 cross each other on each side like the letter X ; the extremities of the outer border are 
 attached to the posterior clinoid processes, and form on each side a sort of bridge, near 
 the apex of the pars petrosa, beneath which the fifth cranial nerve passes ; the extremi- 
 ties of the inner border are prolonged above those of the outer border, and are attached 
 to the anterior clinoid processes. They form the sides of the pituitary fossa, and con- 
 tain in their substance the cavernous sinuses. 
 
 The Falx Cerebelli. — This is a small falciform fold, situated vertically in the median 
 line (le septum median du ceverlet, Chauss.) ; Winslow remarks that it is sometimes 
 double. It extends from the internal occipital protuberance to the foramen magnum, 
 and separates the two hemispheres of the cerebellum. Its base, directed upward, cor- 
 responds with and is attached to the tentorium cerebelli ; its apex bifurcates upon the 
 sides of the foramen magnum. Its posterior border corresponds with the internal crest 
 of the occipital bone, and its anterior border with the bottom of the median fissure of the 
 cerebellum. 
 
 Structure. 
 
 The dura mater is perhaps the thickest and strongest of all the membranous invest- 
 ments of the viscera. It may be regarded as consisting of two veiy distinct fibrous lay- 
 ers : of an external or periosteal layer, which forms the internal periosteum of the bones 
 of the cranium ; and of an internal or proper cerebral layer, which, though blended with the 
 preceding throughout the greatest part of its extent, is separated from it at certain points, 
 in order to form both the fibrous canals, which are called the sinuses, and also the sev- 
 eral folds just described as projecting from the internal surface of the dura mater. Thus, 
 the periosteal layer of the dura mater enters into and lines the longitudinal groove, but 
 the central layer passes off from it on either side ; and the two laminae thus formed by 
 the right and left portions of the cerebral layer approach each other, so as to include 
 between themselves and the periosteal layer lining the groove a long three-sided inter- 
 val, which forms the superior longitudinal sinus. 
 
 The internal layer of the dura mater, which is essentially fibrous, must not be con- 
 founded with the arachnoid membrane by which its internal surface is lined, and which 
 will be presently described. 
 
 The dura mater is evidently composed of fibrous, not of muscular tissue, as was for a 
 long time believed.* 
 
 It consists of fibres which interlace in various directions 
 
 Anatomists generally describe, in connexion with the dura mater, those white granu- 
 lar bodies which are chiefly collected into clusters along the superior longitudinal sinus, 
 and which are improperly called glands (the glands of Pacchioni, from the name of the 
 author who first gave a good description of them). 
 
 These bodies are not found in infants, but exist almost constantly in the adult, and 
 are very numerous in old subjects. They are sometimes single and sometimes collect- 
 ed into groups ; they are, at first, formed upon the internal surface of the dura mater, 
 but after a time they displace the fibres of the internal layer, and separate them into 
 small, parallel, or reticulated fasciculi, and, in this way, insinuate themselves between 
 the two layers of the membrane. In this situation they form tumours, which project 
 upon the external surface of the dura mater, and occupy corresponding depressions form- 
 ed in the bones of the cranium. The rough and irregular depressions so frequently 
 found in the parietal bones of old subjects, and ascribed by the older anatomists to caries 
 of the bone, are occasioned by the clusters of these granular bodies. 
 
 These bodies often insinuate themselves along the obliquely running veins into the 
 substance of the walls of the sinuses, and project into the interior of the veins and si- 
 nuses, so as apparently to be in direct contact with the blood ; but they are, in reality, 
 separated from that fluid by the lining membrane of the vessels and sinuses. 
 
 Although these bodies are principally collected along the superior longitudinal sinus, 
 they are also found, as Haller remarks, opposite the anterior extremity of the straight 
 sinus. I have seen a small pedunculated mass of them, which projected into the inte- 
 rior of the horizontal portion of one of the lateral sinuses, and might have impeded the 
 circulation. 
 
 I consider that the bodies in question are seated in the sub-arachnoid cellular tissue ; 
 in fact, they are often found beneath the arachnoid, at some distance from the longitu- 
 dinal sinus, along the superior cerebral veins. They always project at first upon the in- 
 ternal surface of the dura mater, and then insinuate themselves into the substance of 
 that membrane. 
 
 What is the nature of these bodies 1 Ruysch noticed them, and considered them to 
 be of a fatty nature. Some authors have likened them to the granulations so frequently 
 
 * Pacchioni, who wrote a treatise of some length upon this membrane, even went so far as to admit the exist- 
 ence of three fleshy bellies, viz., one for each hemisphere, and a third for the cerebellum. The same author 
 gives a very minute description of the direction of the different layers of fibres in the dura mater. I do not 
 believe that there exists in the history of our science a more striking example of the misapplication of tcitu- 
 
 r;il anaton.y. 
 
686 NEUROLOGY. 
 
 found in the choroid plexuses ; but there is not the slightest resemblance between the 
 two. Pacchioni regarded them as glands which secreted a peculiar lymph. He has 
 even described certain, so called, excretory ducts, which have been said by others to 
 enter the superior longitudinal sinus. Those clusters which project into the sinuses 
 have been supposed to act as valves. It has been said that these bodies are lymphatic 
 glands ; this, also, is erroneous ; and, indeed, it is better to confess our ignorance of their 
 nature. They occur so frequently that they cannot be regarded as morbid productions. 
 Their absence in the infant, and their much greater abundance in the old subject than in 
 the adult, are the principal features in their history. 
 
 Vessels. — In respect of the number and size of its vessels, the cranial dura mater 
 seems to form an exception to fibrous membranes in general, which are remarkable for 
 their slight vascularity. It receives, in fact, the following arteries : the middle menin- 
 geal, which is a branch of the internal maxillary artery ; the anterior meningeal, from 
 the ethmoidal artery ; and the posterior meningeal, from the ascending pharyngeal, or 
 pharyngo-meningeal. Nevertheless, if we consider that these vessels are situated be- 
 tween the dura mater and the bones, and that they are ahnost entirely distributed to the 
 bones, we shall be able to account for the apparent anomaly in the number and size of 
 these vessels. 
 
 The veins of the dura mater are two venae comites for each meningeal artery, and the 
 small veins which enter the sinuses ; the venous sinuses themselves are situated be- 
 tween the two layers of this membrane. 
 
 The lymphatics form a network upon the internal surface of the dura mater, but do not 
 appear to belong to the proper fibrous tissue. 
 
 Nerves of the Dura Mater. — On consulting the various writers upon this subject, it is 
 found to be involved in the strangest perplexity : some authors admit, while others deny 
 in the most positive manner, the existence of nerves in this membrane ; and those who 
 do admit their existence, differ altogether in regard to their origin. 
 
 Modem anatomists, with Haller, Wrisberg, and Lobstein, state that there are no 
 nerves in the dura mater ; on the other hand, Vieussens, Winslow, Lieutaud, Lecat, Val- 
 salva, and others, declare that they have observed them. Valsalva says that they are 
 derived from the seventh pair ; all the other authors state that they arise from the fifth ; 
 but they do not agree as to the exact point of origin, which, according to some, is the 
 Gasserian ganglion ; and according to others, either the ophthalmic, or the superior or 
 inferior maxillary divisions of that nerve. Chaussier admits their existence, and says 
 that they are derived from the ganglionic system ; but it is evident that he has been led 
 to this conclusion from theory, and not from actual observation. 
 
 Accident has enabled me most distinctly to demonstrate nerves in the dura mater. 
 In a head which had been macerated in diluted nitric acid, and afterward in water, the 
 dura mater having become transparent and jelly-like, I was surprised to see within its 
 substance certain white lines exactly resembhng nervous filaments. I cut down to these 
 white lines, ascertained that they were nerves, and dissected them throughout their 
 whole course. I recognised on each side of the middle line two nervous filaments which 
 came from the fifth nerves, and reached nearly to the superior longitudinal sinus. There 
 was a third nervous filament in the substance of the tentorium cerebelli, but I could not 
 ascertain its origin.* 
 
 Uses of the Cranial Dura Mater. — The dura mater serves as an internal periosteum for 
 the bones of the cranium, with which it has numerous vascular connexions ; and it also 
 covers and defends the encephalon. Its prolongations separate from each other the dif- 
 ferent parts of the encephalon, and in some measure prevent the effects of concussion. 
 It also contains within its substance certain venous canals, in which aU the blood is re- 
 turned from the encephalon. 
 
 The Spinal Portion of the Dura Mater. 
 
 The spinal portion of the dura mater forms a long fibrous tube, which is prolonged from 
 the cranial dura mater, and extends from the occipital foramen to the termination of the 
 sacral canal. 
 
 In order to ascertain the capacity of this fibrous sheath, it must be first distended with 
 an injection : it is then seen to form a funnel-shaped tube, which is of considerable size 
 in the cervical region, becomes contracted in the dorsal region, is again expanded in the 
 lumbar region, and terminates in the sacral region by subdividing into a number of sheaths 
 for the sacral nerves. When distended, the spinal portion of the dura mater almost en- 
 tirely fills the bony canal formed by the vertebral column. Why the cavity of the dura 
 mater (d, fig. 266, A B) should be larger than the spinal cord (s), a question the solution 
 of which had exercised the ingenuity of almost all anatomists, has been well answered 
 by Cotugno — it is for the purpose of containing a serous fluid, t 
 
 * [The tentorium receives a branch from the fourth cranial nerve (see description of that nerve).] 
 
 t " Quidciuid autera spatii est inter vaginam durae matris et meduUam spinalem, id omne plenum etiam sem 
 
 per est ; non medullft. quidem ips& in viventibus turgidiori, non nube vaporos^, quod in re adhuc obscurft sus 
 
 picantur summi ^nri ; sed aqu& ei quidem simili, quam circa cor coutinet pericardium, quae caveas cerebri ven 
 
 triculorum adimplet, quae auris labyrinth um, quae reliquas tandem complet corooris caveas, libero aeri, nequa 
 
 " — ' rjf Ischiade Nervosa, p. U.) 
 
THE CRANIAL PORTION OF THE ARACHNOID. 
 
 The external surface of the spinal portion of the dura mater, unlike, in this respect, to 
 the cranial portion, scarcely adheres to the bony parietes of the spinal canal. Covered 
 by a plexus of veins behind, it has no attachment at all to the arches of the vertebrae, nor 
 to the yellow ligaments ; the intervals between those parts and the membrane is occu- 
 pied by a soft, reddish, adipose tissue intermixed with veins, which, in the foetus, and 
 during infancy, is infiltrated with serosity. This fat, which is most abundant in the sa- 
 cral region, may be most aptly compared to the marrow of the long bones, with which 
 it has so much analogy in respect of its use. In one class of vertebrated animals, viz., 
 fishes, a precisely similar kind of fat is accumulated in large quantities in the cranium, 
 always filling up the spaces left by the contained organs. 
 
 In front, the external surface of the dura mater adheres to the posterior common ver- 
 tebral ligament by fibrous bands prolonged from it at intervals. 
 
 On each side, the spinal portion of the dura mater gives off fibrous sheaths {I, fig. 266 ; 
 h', fig. 267) for the roots of the spinal nerves (w), which sheaths accompany the nerves 
 beyond the inter-vertebral foramina, and are lost in the cellular tissue. 
 
 The internal surface of this part of the dura mater is smooth and moist, in consequence 
 of being covered by a serous layer, viz., the arachnoid (a). Down each side of this sur- 
 face are seen the double orifices of the several fibrous canals, which transmit the ante- 
 rior and posterior roots of the spinal nerves. It is very rarely found entirely free from 
 adhesions to the arachnoid ; and it is necessary to be careful not to confound these ad- 
 hesions, which are always met with at isolated points, with such as are the result of 
 morbid action. 
 
 The inferior extremity of the spinal portion of the dura mater is situated opposite the 
 bottom of the lumbar region, and it therefore extends much lower than the spinal cord ; 
 this extremity is formed into a large ampulla around the cauda equina, which enlarge- 
 ment seems to be of use only as a reservoir for the cephalo-rachidian fluid. 
 
 Its superior extremity is firmly attached to the margin of the foramen magnum, and is 
 continuous with the cranial portion of this membrane. In consequence of the firm ad- 
 hesion of this membrane to the margin of the foramen magnum, and of its attachment 
 to the sacrum by means of the sheaths for the sacral nerves, and to the sides of the ver- 
 tebred column by those for the cervical, dorsal, and lumbar nerves, it is constantly main- 
 tained in a state of tension highly favourable to its use as a protecting covering of the 
 spinal cord. 
 
 Vessels. — The vessels of the spinal dura mater are much less numerous than those of 
 the cranial portion ; for these belong exclusively to it, and not to the surrounding bones. 
 
 Its arteries arise from the spinal branches of the arteries of the cervical, dorsal lum- 
 bar, and sacral regions. Its veins terminate in the intra-spinal veins. 
 
 The lymphatic vessels observed appear rather to belong to the arachnoid. 
 
 The nerves of this membrane have not yet been demonstrated ; but experiments upon 
 living animals, especially upon dogs, have convinced me that the cranial, and probably, 
 also, the spinal portion of the dura mater, although insensible to the knife, are extreme- 
 ly sensible to laceration. 
 
 The Arachnoid. 
 The cerebro-spinal axis is surrounded by a serous membrane named the arachnoid, 
 which, like all membranes of this kind, forms a shut sac, adherent by its external sur- 
 face, but free and smooth on its internal surface. We shall first describe the cranial, and 
 then the spinal portion of the arachnoid. 
 
 The Cranial Portion of the Arachnoid. 
 
 Dissection. — The arachnoid may be shown upon the convex surface of the brain with- 
 out any preparation, if the sub-arachnoid cellular tissue be infiltrated. It can also be 
 very easily demonstrated by blowing air under it. 
 
 The arachnoid membrane, which, from its extreme tenuity, was for a long time con- 
 founded with the pia mater, was demonstrated by Ruysch upon the convex surface of 
 the brain by injecting air beneath it ; it was shown by Varolius upon the base of that 
 organ, and its arrangement in that situation was figured by Casserius. It was descri- 
 bed first by the Anatomical Society of Amsterdam as a special membrane covering the 
 brain, under the name of the arachnoid; and Bichat, reasoning from analogy, demonstra- 
 ted that it not only forms a covering for the brain, but is also reflected upon the dura 
 mater, and lines it through its whole extent. He also believed that it was continuous 
 with the lining membrane of the ventricles, an error which has been successfully refu- 
 ted by M. Magendie. 
 
 Like all serous membranes, the arachnoid presents a visceral and a parietal layer 
 
 The Visceral Layer of the Arachnoid. 
 
 The visceral layer of the cranial portion of the arachnoid requires to be exammed upon 
 the convex surface and the base of the brain. 
 
 Upon the base of the brain, the arachnoid is separated from this organ in a great num- 
 
NEUEOLOGY. 
 
 ber of points, and more particularly as it is passing from one lobe to another. We shdll 
 -examine in detail the arrangement of this part of the membrane. 
 
 In the median line, in frmit, it dips between the anterior lobes of the brain, but only at 
 the fore part ; behind, it connects these lobes by passing directly from one to the other ; 
 it covers the lower surface of the optic nerves and optic commissure, then the tuber 
 cinereum and the infundibulum, for the latter of which it forms a sheath, and is then re- 
 flected above the pituitary body ; from the tuber cinereum it passes across to the pons 
 Varolii, leaving a hollow space between it and the brain, which is traversed by a few 
 dense fibrous filaments. 
 
 I shall call this space the anterior sub-arachnoid space ; it may be regarded as the prin- 
 cipal reservoir of the serous fluid of the cranium. 
 
 In the median line, lehind, the arachnoid lines the furrow between the posterior lobes 
 of the brain, and is reflected from the corpus callosum upon the superior vermiform pro- 
 cess of the cerebellum : at this point it meets with the venae Galeni, and generally forms 
 a circular fold around them, which was compared by Bichat to the foramen of Wins- 
 low in the peritoneum, and which he supposed to be the orifice of an arachnoid canal, 
 which opened into the third ventricle beneath the velum interpositum. 
 
 The arachnoid covers the whole upper surface of the cerebellum ; and, having reached 
 the great circumference of that organ, it passes like a bridge from one hemisphere to the 
 other, and from the cerebellum itself to the posterior surface of the spinal cord. In thus 
 passing from one hemisphere of the cerebellum to the other, and from the cerebellum 
 to the spinal cord, the arachnoid leaves a considerable space or reservoir for serosity, 
 which may be called the posterior sub-arachnoid space. 
 
 Laterally, the arachnoid covers the inferior surface of the anterior lobes of the cere- 
 brum and the olfactory nerves, which are thus held in contact with the anterior lobes ; 
 it then passes from the anterior to the posterior lobe, without entering the fissure of 
 Sylvius, and from the posterior lobe to the tuber annulare and the cerebellum. It fol- 
 lows, therefore, that there are certain small sub-arachnoid spaces which communicate 
 with the great anterior sub-arachnoid space of the brain ; so that in the dead body there 
 exists, between the arachnoid and the pia mater, at the base of the brain, a large space, 
 the centre of which corresponds to the median excavation of the base of the cerebrum, 
 and which is prolonged forward between the anterior lobes of the brain, laterally along 
 each of the fissures of Sylvius, and backward, around the peduncles of the cerebellum. 
 By this last-named prolongation a communication is established between the anterior 
 and posterior sub-arachnoid spaces. All these spaces contain serum in the natural 
 state, and coagulable lymph in some cases of inflanmiation of the sub-arachnoid cellular 
 tissue. 
 
 The arachnoid is arranged in a uniform manner in reference to all the nerves situated 
 at the base of the brain ; it passes over their lower surface, and therefore holds them 
 firmly against the under surface of the brain ; but where these nerves are separated 
 from the brain it furnishes a tubular prolongation around each, and again leaves them 
 as they are about to enter the foramina in the base of the scull, and is reflected upon the 
 dura mater. 
 
 Upon the upper surface of the brain, the arachnoid dips into the median fissure, and is 
 reflected from one hemisphere to the other immediately below the free margin of the falx 
 cerebri ; and as this margin is nearer to the corpus callosum behind than in front, it fol- 
 lows that the anterior portions of the two hemispheres are in contact with each other 
 for a certain distance, or, rather, they are merely separated by the pia mater. 
 
 The cerebral arachnoid adheres intimately to the arachnoid of the dura mater, along 
 the sides of the superior longitudinal sinus, by means of the tubular prolongations which 
 it forms around the cerebral veins that enter that sinus. This adhesion is also strength- 
 ened by the granular bodies called the glands of Pacchioni, which, as we have already 
 stated, lie in the substance of the dura mater. 
 
 Moreover, on the convex surface, as well as upon the base of the brain, the arachnoid, 
 in covering this organ, passes, like a bridge, from one convolution to another, never dip- 
 ping into the intermediate sulci. 
 
 The cellular tissue, which unites the arachnoid to the pia mater, is of a serous nature 
 and extremely delicate, so that the two membranes can be easily separated, excepting 
 in cases of inflammation. When air is blown beneath the arachnoid, the extreme tenu- 
 ity of this cellular tissue becomes evident : it is very frequently infiltrated with a serous 
 fluid. 
 
 The sub-arachnoid cellular tissue never contains any fat. The fat which Ruysch, 
 Haller, and other anatomists say they have observed, must have been that yellowish, 
 gelatiniform lymph so commonly met with in cases of inflammation.* 
 
 In some parts the arachnoid is lined by a fibrous tissue, which gives it great strength. 
 This fibrous tissue, which may be regarded as a prolongation of the neurilemma of the 
 spinal cord, is especially distinct in the great furrows of the brain. Thus we find it 
 
 * I onoe found in an old woman an adipose cyst, about the size of a small grape, arising by a very thin ped- 
 icle from the upper surface of the pituitary body. 
 
THE PARIETAL LAYER OP THE ARACHNOID. 689 
 
 around the great anterior sub-arachnoid space, where it constitutes, as it were, a very 
 strong fibrous band, which surrounds the arterial circle of Willis, situated at the base of 
 the brain ; it also retains the different parts of the brain in their relative positions, even 
 when that organ is removed from the cranium, and is laid with its base uppermost. 
 The Parietal Layer of the Arachnoid. 
 
 The internal surface of the dura mater is lined with a very delicate and closely-ad- 
 herent serous membrane, which, owing to these two qualities, for a long time escaped 
 the notice of anatomists. It was only by reasoning analogically from the structure of 
 all other serous membranes, that Bichat was led to enter upon the inquiry which ended 
 in the discovery of the parietal portion of the arachnoid. This portion is quite distinct 
 from the internal layer of the dura mater, the existence of which we have admitted 
 with several anatomists. Upon a mere inspection, we should say that it does not exist, 
 because, from its transparency, the fibrous bundles of the dura mater can be seen as dis- 
 tinctly as if they were not covered. But if a very superficial incision be made upon the 
 inner surface of the dura mater, some extremely thin shreds may be detached by the 
 aid of the forceps. Lastly, ecchymosis not unfrequently occurs between the dura mater 
 and the arachnoid.* Ossilic deposites in the dura mater, especially those found in the 
 falx cerebri, being found beneath the arachnoid, sometimes enable us to detach this lat- 
 ter membrane in the most distinct manner. 
 
 It still remains, however, to describe the mode in which the parietal and cerebral por- 
 tions of the arachnoid become continuous with each other. It has been stated that the 
 arachnoid membrane forms tubular prolongations around each of the nerves which are 
 given off from the base of the brain, and around each of the veins which enter the dif- 
 ferent sinuses ; these prolongations just enter the fibrous canals formed by the dura 
 mater for these nerves and veins, and almost immediately terminate by being reflected 
 upon the dura mater itself ; so that the arachnoid forms a sort of cul-de-sac around the 
 cranial orifice of each fibrous sheath of the dura mater. In order to see the funnel- 
 shaped prolongations of the arachnoid, it is convenient to examine them when the brain 
 is being lifted up from before backward, in order to expose and divide the nerves which 
 are attached to the base of the scuU. The tubular prolongations being then dragged 
 upon, they become very distinct. Not unfrequently, the development of adventitious 
 false membrane on the base of the brain also extends along these prolongations. 
 
 The arachnoid does not enter into the interior of the ventricles, below the posterior 
 border of the corpus callosum. The arachnoid canal, called the canal of Bichat, does not 
 exist, but it is formed by the very experiment made to demonstrate it. The following 
 is the statement of Bichat regarding this alleged canal : 
 
 " The brain being exposed from behind and allowed to remain in its natural position, 
 the back part of each posterior lobe is to be raised, and drawn gently outward ; the ve- 
 nae Galeni are then seen emerging from the canal by which they are embraced, and the 
 oval orifice of which is now very apparent. Sometimes, however, the margin of this 
 orifice embraces the veins so closely, that it can only be recognised by a small fissure 
 on each side, and the parts, at first sight, would appear to be continuous. If a probe be 
 then glided from behind forward along these vessels, and when it has penetrated a short 
 distance, if it he turned all round the veins it will destroy the adhesions, and the opening vnH 
 become very evident. 
 
 " In order to be convinced that this opening leads into the middle ventricle of the 
 brain, a grooved director must be introduced below the venae Galeni and pushed gently 
 forward : it will enter the ventricle without difficulty. The corpus callosum and the for- 
 nix are then to be removed, and the velum interpjjsitum left untouched. Next, dividing 
 the velum on the director, the membrane will be found to be smooth and polished in the 
 whole of its course, and nowhere lacerated by the introduction of the director. Occa- 
 sionally some resistance is experienced to the entrance of the director, which may even be com- 
 pletely arrested : this depends upon the fact that the veins which enter the vena Galeni inter- 
 lace in all directions within the canal, so as to form a network, which arrests the instrument. 
 If this be the case, it should be withdrawn, and, in order to demonstrate the communi- 
 cation, some mercury should be poured into the external opening, and, by inclining the 
 position of the head, this fluid will flow into the middle ventricle. Air blown into the 
 canal will also enter that ventricle, and will pass from it into the lateral ventricles through 
 the openings behind the anterior pillars of the fornix. If the fornix be removed, and 
 the velum be exposed, the latter will be seen to be elevated each time that the air is 
 blown in. 
 
 " The internal orifice of this communicating canal is at the lower part of the velum 
 interpositum ; in order to see it, this membrane must be reflected backward, either with 
 the fornix, the under surface of which it covers, or after it has been separated fram that 
 part of the brain. The pineal gland which adheres to the velum is also to be turned 
 
 * As to the collections of blood which are said to have been met with between the arachnoid and the dnra 
 mater, M. Baillarget has clearly shown, in several preparations which he presented to the Anatomical Soci- 
 ety, that the supposed laver of arachnoid is a newly- formed membrane, having all the appearances of a serous 
 membrane. 
 
 4 S 
 
690 ' VEUROLOGY. 
 
 back ; below and in front of this gland is then seen a row of cerebral granulations, ar- 
 ranged in the form of a triangle, having its point turned forward. The internal orifice 
 of the canal of the arachnoid is at the base of this triangle." 
 
 Now, if we make the dissection described by Bichat, it is easy to see that there exists 
 at the back part of the brain, below the corpus callosum, a circular or oval opening, lead- 
 ing into a sort of cul-de-sac, which is of variable depth, and is formed by the reflection 
 of the arachnoid around the venae Galeni : it is seen, also, that the bottom of this cul-de- 
 sac may be easily lacerated by a blunt probe, which may then be passed beneath th< 
 velum interpositum, as Bichat has pointed out ; but it is through an artificial canal. 
 Moreover, if a coloured liquid be injected into the ventricles, it can never be made to 
 escape through this imagined canal of Bichat ; and so, on the other hand, if a liquid be 
 thrown into the orifice of this canal, it never enters the third ventricle : mercury enters 
 only by lacerating the parts ; and the same is the case with air. Analogy, which has 
 so often conducted Bichat to beautiful and grand discoveries, has, therefore, misled him 
 in this particular. 
 
 Since, then, the arachnoid canal of Bichat does not exist, it will be necessary to de- 
 termine how the ventricles communicate with the external arachnoid cavity. This 
 question we shall discuss presently.* 
 
 The Spinal Portion of the Arachnoid. 
 The spinal cord, besides its own proper investment, is covered by a transparent mem- 
 brane of extreme tenuity, and only to be demonstrated properly by raising it with the 
 forceps, or by subjecting it to the mode of preparation above described : this is the vis- 
 ceral layer of the spinal portion of the arachnoid. 
 
 The visceral layer (b, fig. 266, A B) forms a membranous sheath, which is much larger 
 than the spinal cord (*) ; hence it is named the loose arachnoid. It is 
 prolonged around the bundle of nerves called the cauda equina, and forms 
 around each nerve a funnel-shaped sheath, which terminates in a cul- 
 de-sac at the corresponding inter-vertebral foramen, by being reflected 
 upon the inner surface of the fibrous sheath formed for the nerve by the 
 dura mater (see^^. 266, B). 
 
 There exists, then, between the spinal cord and the visceral portion 
 of the arachnoid a considerable space (e, fig. 266, A B), which can be 
 best displayed by inflating it, or injecting it with some liquid. This 
 space, as we shall immediately show, contains a serous fluid. 
 
 We have seen that, opposite the median excavation at the base of 
 the brain, the arachnoid adheres to the cerebral pia mater only by means 
 of long fibrous filaments. The spinal arachnoid also adheres to the proper covering of 
 the cord by means of fibrous filaments ; but in no part does there exist any delicate sub- 
 arachnoid cellular tissue, like that found beneath the cerebral arachnoid.! 
 
 Another peculiarity in the visceral layer of the spinal portion of the arachnoid is this, 
 that it adheres to the parietal layer in a number of points. 
 
 The parietal layer (a) of the spinal portion of the arachnoid is arranged precisely in the 
 same manner as the parietal layer of arachnoid in the scull. It becomes continuous 
 with the visceral layer opposite the sheaths which are formed by the latter around the 
 spinal nerves. 
 
 The Sub-arachnoid Fluid. 
 
 There exists around the spinal cord a serous fluid, in quantity suflicient to occupy the 
 interval left between the cord and the dura mater : this fluid is seated in the sub-arach- 
 noid space (e). A similar fluid exists in the ventricles of the brain and in the sub-arach- 
 noid cellular tissue, and fills the free spaces of the cranial cavity.t 
 
 The existence of the sub-arachnoid fluid was pointed out by Haller (Elcmcnta fhysi- 
 ologicB, t. iv., 87), and most explicitly and completely demonstrated by Cotugno (I>e ischi- 
 ade nervosa commcntarium), but the fact was neglected by anatomists, and the fluid re- 
 garded by some as the result of cadaveric exudation, and by others as that of a morbid 
 action. The existence of this fluid has been again confirmed by M. Magendie, who, 
 moreover, has clearly proved that it is seated in the sub-arachnoid tissue. 
 
 In order to prove the existence of the sub-arachnoid fluid, or cephi o-iaunoian nuid 
 
 * [The existence of the canal of Bichat is admitted by Arnold, a recent authority. Perhaps the opposite 
 statements of anatomists concerning this canal may depend on the fact that the canal itself, though originally 
 present, is sometimes closed subsequently, and at other times remains open.] 
 
 t [The spinal sub-arachnoid space is divided behind by a thin, and, in some parts, cribriform longitudinal 
 septum, which extends from the loose arachnoid to the posterior median fissure of the cord. This space is 
 probably4i>ied throughout by a serous membrane, which contains the rachidian fluid, and which might be 
 named the internal arachnoid. The septum just mentioned may be supposed to consist of two layers of thJB 
 membrane reflected from the loose arachnoid to the cord, and having the same relation to it as the mesentery 
 has to the intestine ; and the membrane itself may be conceived to.be prolonged through the foramen described 
 by Magendie at the Ijottom of the fourth ventricle (see p. 718), so as to form the lining membrane of the fourth, 
 third, and lateral ventricles ; and, farther, in case of the existence of the foramen of Bichat, to become con- 
 tinuous with the external or true arachnoid through that foramen.] 
 
THE SUB- ARACHNOID FLUID. 691 
 
 of Magendie, it is necessary to open the lumbar region of the spinal canal in a certain 
 number of subjects. If an incision be very carefully made through the dura mater, it 
 will be seen that the serous fluid raises the visceral layer of the arachnoid, so as to make 
 it protrude like a hernia through the incision : if this layer of arachnoid be then divided, 
 the liquid will escape. Cotunni, who performed this experiment upon tw^enty subjects, 
 collected from four to five ounces of fluid in each case. 
 
 To the objection that this fluid is found after death, but does not necessarily exist in 
 the living subject, we may answer thus : There is a space between the spinal cord and 
 the dura mater, and the brain itself does not exactly fill the cranial cavity. Now in no 
 part of the animal body does there exist any vacuum ; the spaces between the solids are 
 always filled either with liquids or gaseous fluids. But if it be said that in this situation 
 the space is filled by a serous vapour, the elasticity of which might establish an equilib- 
 rium with the external air, it may be replied, that this vapour would not be sufficient to 
 produce so large a quantity of fluid as is found in the spinal canal. 
 
 Moreover, all these objections, and also the supposition that the brain and spinal cord 
 may be smaller after death than during life, are overthrown by the following experiment. 
 If the posterior cervical muscles be divided in a living dog, at their occipital attachments, 
 the posterior occipito-atlantoid ligament will be exposed. The parts being weU cleansed 
 from blood, the ligament must be cut away, layer by layer, with a scalpel held flat against 
 it. The ligaments will scarcely be cut through before a small hernial protrusion, con- 
 taining a fluid, will be seen ; this consists of the visceral arachnoid raised by the rush 
 of fluid. If a crucial incision be then made in the occipito-atlantoid ligament, by the aid 
 of a director,* a fluid as limpid as distilled water will be seen beneath the visceral layer 
 of the arachnoid, which fluid is agitated by two kinds of motion, one of which is isochro- 
 nous with the pulse, and the other with the respiratory movements. If the arachnoid 
 be next punctured, the fluid will immediately escape in jets, and its quantity may be as- 
 certained. 
 
 The difficulty of not wounding the visceral layer of the arachnoid explains why, until 
 recently, it was thought that the spined fluid was contained within the arachnoid cavity 
 {c,jig. 266), i. e., between the two layers of the arachnoid membrane, although most ob- 
 servers had noticed that the serous fluid in the cranium occupied the sub-arachnoid cel- 
 lular tissue. It follows, therefore, that besides the fluid which is exhaled from the free 
 surface, i. e., into the cavity of the arachnoid, a certain quantity of a similar fluid fills up 
 the areolar tissue of the sub-arachnoid space : in this respect the arachnoid differs es- 
 sentially from other serous membranes, all of which pour their secretions into their cav- 
 ities, and not into the subjacent cellular tissue. 
 
 This peculiarity depends simply upon the non-adhesion of the arachnoid to the spinal 
 cord ; it may be stated as a law, that serous membranes exhale almost indifferently 
 from either their internal or their external surface, when the latter surface is not adhe- 
 rent. The arachnoid exhales a fluid from both surfaces ; a certain quantity of fluid is 
 rather frequently found between its two layers ; and although, in acute inflammations, 
 the deposite of purulent matter or of false membranes most generally takes place in the 
 sub-arachnoid cellular tissue, yet these morbid products are not unfrequently found in 
 the cavity of the spinal arachnoid itself 
 
 The sub-arachnoid fluid exists not only in the vertebral canal, but also within the cra- 
 nium, in which it fills up all the spaces between the brain and the dura mater. 
 
 Now these spaces are subject to much variety in size in different individuals, or from 
 age or from disease : thus, in atrophy of the brain and spinal cord, from old age or dis- 
 ease, the interval between the dura mater and the cerebro-spinal axis is augmented, and 
 the quantity of fluid increases in the same proportion. 
 
 The quantity of the sub-arachnoid fluid is in a direct ratio with the progress of age ; 
 in aged lunatics, in whom the convolutions of the brain are much atrophied, the quanti- 
 ty of this fluid contained within the cavity of the cranium is very great, t 
 
 The sub-arachnoid fluid in the cranium is not distributed equally around the brain, but 
 is chiefly seated at its base. In order to show this fluid, it is merely necessary to raise 
 up the brain carefully from before backward, when it will be seen distending all the fun- 
 nel-shaped prolongations formed by the arachnoid around the nerves, and it will escape 
 as soon as the membrane is divided. 
 
 As regards quantity, the sub-arachnoid fluid at the base of the brain and the fluid of 
 the ventricles are always directly proportioned to each other, but are inversely propor- 
 tioned to the sub-arachnoid fluid upon the convex surface of the brain. Upon opening 
 the head of infants who have died from acute ventricular hydrocephalus, we sometimes 
 
 * It is highly important to make the transverse incision very short, in order to avoid injuring- the very large 
 vertebral veins ; for if these vessels be cut, the hemorrhage will be so abundant as to prevent the continuation 
 of the experiment. 
 
 t None of these facts escaped the notice of Cotugno : 
 
 " Nee tantnm 'axe aqua complens ab occipite ad usque imum os sacrum, tubum dun-e matris . . . sed et u 
 ipso redundat calcarise cavo omniaque complet intervalla quae inter cerebrum et durse matris ambitum )nven> 
 antur .... quantum autem magnitudinis cerebrum in his perdit, tantum a contactu subtrahitur durs matns 
 et quidquid loci decrescendo reliquit, aquosus vapor coUectus lotum adimplet." — (Op. cit., p. 11. 12.) 
 
692 NEUROLOGY. 
 
 find the convex surface of the brain dry, and, as it were, adhesive. It is of importance 
 to determine whether the cavities containing the cephalic and the spinal fluids commu- 
 nicate with each other. There can be no doubt that the sub-arachnoid spaces of the 
 brain communicate with the sub-arachnoid space around the spinal cord ; but do the 
 cavities of the ventricles communicate with the sub-arachnoid space 1 
 
 Haller admitted that the fluid could flow from the ventricles into the spinal canal, and 
 he believed that this was effected by a communication between the ventricles and the 
 cavity of the arachnoid itself* Cotugno expresses the same opinion still more distinct- 
 ly. Both Haller and Cotugnot thought that this communication occurred at the bottom 
 of the fourth ventricle, but they neither indicated the exact situation, nor the mode in 
 which it is effected. M. Magendie has pointed out that it occurs at this very spot, near 
 the point of the calamus scriptorius. Bichat stated that the communication between the 
 ventricles and the arachnoid cavity was at the so-called canal of Bichat. The mode in 
 which the fourth ventricle communicates with the sub-arachnoid space will be much 
 better understood if stated in our description of that ventricle, t 
 
 Uses of the Arachnoid and of the Sub-arachnoid Fluid. 
 
 Uses of the Arachnoid. — Like all serous membranes, the essential use of the arachnoid 
 is to lubricate the surface of the brain and spinal cord, and thus facilitate their move- 
 ments. No other membrane more completely fulfils such a use, for the arachnoid is 
 moistened in both its external and internal surfaces. It would, in fact, be an error to 
 suppose that the serous secretion is poured out solely by that surface of the arachnoid 
 which is turned towards the pia mater : the fluid is exhaled upon its internal surface 
 also, as in all other serous membranes, so that we sometimes find serum, pus, and false 
 membranes in the cavity of the arachnoid itself 
 
 Uses of the Sub-arachnoid Fluid. — The sub-arachnoid fluid forms a sort of bath around 
 the spinal cord, which effectually protects it during the various motions of the vertebral 
 column. It might be said that the spinal cord, being, in reference to its delicacy, in con- 
 ditions somewhat analogous to those of the foetus in utero, requires a similar method of 
 protection ; and in this point of view the sub-arachnoid fluid exactly represents the liquor 
 of the amnios. 
 
 As to the other uses which have been attributed to it, they are all more or less hypo- 
 thetical. 
 
 If we open the spinal canal of a dog, between the atlas and the occipital bone, some 
 fluid will immediately gush out ; air is drawn in, which is forced out in bubbles during 
 expiration, and again enters during inspiration. If the animal be then left to himself, he 
 will stagger like a drunken man ; he will crouch into a comer, and remain in a drowsy 
 state for some hours. On the next day he will walk about again perfectly well. I have 
 repeated this operation several times upon the same dog, until at last he became accus- 
 tomed to it, at least as far as regards the physiological effects resulting from the remo- 
 val of the fluid, by which means the slight pressure usually exercised upon the spinal 
 cord was removed. 
 
 The Pia Mater. 
 
 The pia mater is the innermost of the three membranes of the encephalon and spinal 
 cord. It consists of an extremely delicate membrane, or, rather, of a vascular network, 
 which inunediately invests the nervous axis, and which may be regarded as the nutri- 
 tious membrane of the parts that are covered by it. In fact, the arterial vessels divide 
 into an infinite number of branches within this membrane before they enter the nervous 
 substance, and so, also, the veins which pass out from the brain and spinal cord unite 
 into small, and then into larger vessels, which form part of this same network. These 
 vessels are supported by a very delicate serous cellular tissue : to this is added, in some 
 regions, a certain amount of fibrous tissue, which converts the membrane into a very 
 strong fibrous structure, having all the characters of the neurilemma, or proper invest- 
 ment of the nerves. 
 
 The characters of the spinal portion of the pia mater are so distinct from those of the 
 cranial portion, that it will be better to postpone the description of the former until we 
 are treating of the spinal cord, of which it constitutes the proper covering. 
 
 The Cranial Portion of the Pia Mater. 
 This portion, or the cerebral pia mater, does not merely enclose the brain like the arach- 
 noid, but dips into the sulci or anfractuosities on its external surface, and penetrates into 
 the interior of the ventricles. That portion of the pia mater which invests the brain is 
 
 * " Qua prodit de ventriculo aqua, facili in medullse spinalis circumjectum spatium etiam parat ; earn aquam 
 enim difficulter omnino in tertium ventriculum et ad infundibulum redderet, quoad perpendiculum oportet a»- 
 cendere (Haller, torn, iv., sect. 3, p. 77) . . . Non dubito quin coUecta ex ventriculis cerebri aqua eo descen- 
 dere possit." — (Ibid., sect. 3, p. 87.) 
 
 t " His spinae aquis eas etiam subinde commisceri, quas, sive a majoribos cerebri ventriculis per lacunar et 
 Sylvii aqueductum, sive a propriis exhalantibus arteriis, cerebelli ventriculus accipiat ; cujus positio perpen- 
 diculata et via ad spine cavum satis patens defluxum liumoris in spinam manifest! persuadent." — {Cotugno, 
 p. 18, 19.) t See note, p. 960. 
 
THE EXTERNAL CEREBRAL PIA MATER, ETC. 693 
 
 called the external pia mater, and that which is continued into the ventricles is denomi- 
 nated the internal pia mater. 
 
 The internal pia mater cannot be satisfactorily studied until the internal conformation 
 of the brain is understood, and it will therefore be described together with the ventricles. 
 
 The External Cerebral Pia Mater. 
 
 Dissection. — At the base of the brain, the pia mater is naturally separated from the 
 arachnoid by a considerable space, which is occupied by the sub-arachnoid fluid ; but it 
 is easy to separate these two membranes everywhere by introducing air or water be- 
 tween them. The arachnoid may be easily distinguished from the pia mater in cases 
 of serous or purulent infiltration into the sub-arachnoid cellular tissue. 
 
 The external pia mater is subjacent to the arachnoid, and is connected with it by a very 
 delicate serous cellular tissue ; it not only covers the free surface of each convolution, 
 but also dips into the adjacent sulci ; it passes down on one side of a sulcus, and then, 
 being reflected upon the other, is continued over the free surface of the next convolu- 
 tion, and so on. It follows, therefore, that this part of the pia mater is in contact with 
 itself to a great extent ; and also that its superficies is much larger than that of the 
 arachnoid, so that if the brain could be unfolded, as Gall supposed, its surface would be 
 entirely covered by the pia mater. These remarks apply equally to the pia mater of the 
 cerebellum, for every one of the numerous leuninae of that organ is covered on each side 
 by a fold of the pia mater. 
 
 The internal surface of the pia mater is in contact with the brain, and is united to it 
 by innumerable vessels, which penetrate into the substance of that organ. This adhe- 
 sion, however, is such, that the pia mater can generally be detached without injuring 
 the surface of the brain. 
 
 I do not think, however, with some pathologists, that the adhesion of this membrane 
 to such a degree that it cannot be removed without injuring the substance of the brain 
 is any evidence of disease.* 
 
 For displaying the vessels which pass into the substance of the brain from the pia 
 mater, an asphyxiated subject is very well adapted. But an injected condition of these 
 vessels may be produced by allowing the head of the subject to hang down for some 
 hours. The pia mater will then be not only black from its congested state, but it will be 
 infiltrated with serum ; and if it be detached slowly, an immense number of vascular 
 filaments, looking like hairs, will be seen emerging from the substance of the brain, re- 
 markable for their extreme tenuity and length, and for having no anastomoses. Some 
 drops of blood will indicate the points upon the surface of the brain from which the ves- 
 sels escape, and which, when examined through a lens, prove to be foramina. 
 
 The use of the pia mater is connected solely with the circulation of blood through the 
 brain. This membrane affords to the vessels a very large surface, on which the arteries 
 divide into their capillary branches, and the veins unite into their larger and larger 
 trunks. According to my observations, five sixths of the vessels of the pia mater belong 
 to the venous system. 
 
 The pia mater is the nutritious membrane of the brain, and may thus be regarded as 
 its neurilemma. 
 
 It will afterward be seen that the internal pia mater is connected with the arteries 
 and veins of the walls of the ventricles, ^ust as the external pia mater is with the ex 
 ternal vessels. 
 
 THE SPINAL CORD AND THE MEDULLA OBLONGATA. 
 
 General View of the Cord — its Limits and Situation — the Ligamentum Denticulafum. — Size 
 of the Spinal Cord — Form, Directions, and Relations — the Cord in its proper Membrane — 
 the proper Membrane, or Neurilemma of the Cord — the Cord deprived of its proper Mem- 
 brane. — Internal Structure of the Cord — Sections — Examination by Means of Water — and 
 when hardened in Alcohol — the Cavities or Ventricles of the Cord. — The Medulla Oblonga- 
 ta — Situation — External Conformation — Anterior Surface, the Anterior Pyramids, and the 
 Olivary Bodies — the Posterior Surface — the Lateral Surfaces — the Internal Structure — 
 Sections — Examination by Dissection, and under Water. — Development of the Spinal 
 Cord. — Development of the Medulla Oblongata. — Comparative Anatomy of the Spinal 
 Cord. — Comparative Anatomy of the Medulla Oblongata. 
 
 The spinal cord (fzvelog jidxiTTig, medulla spinalis, a b c, fig. 268)'is that white, round- 
 ish, symmetrical, nervous trunk, which occupies the spinal canal ; it is continuous with 
 the encephalon, of which it has been alternately considered the origin and the termina- 
 tion. It is called the medulla, in consequence of a rude analogy between it and the mar- 
 row of the long bones, in regard to its situation and consistence. Chaussier has sub- 
 
 * In some cases the membranes are so dry that the pia mater cannot be removed without tearing the sub 
 itance of the brain, even when that organ is perfectly healthy. 
 
094 NEUKOLOGY. 
 
 stituted for this term the title of racfddian prolongation, but the generally received name 
 of spinal marrow, which can give rise to no error, might be retained.* 
 
 The Extent and Situation of the Spinal Cord. 
 
 Authors are not agreed as to the superior limit of the spinal cord. The natural limit 
 is evidently at the groove, between the medulla oblongata (a. Jig. 268) and the pons 
 Varolii (e), which groove, on account of the great size of the pons in man, is much more 
 distinctly marked in him than in those vertebrated animals in which the pons is also 
 found. 
 
 The spinal cord is situated in the median line, at the back part of the trunk ; it is be- 
 hind the organs of digestion, circulation, and respiration, t 
 
 The vertebral column, the dura mater, the arachnoid, and the pia mater form a fourfold 
 sheath for the spinal cord ; the first being osseous ; the second, fibrous ; the third, serous ; 
 and the fourth, or proper sheath, both fibrous and vascular ; this last-named membrane 
 is accurately adapted to the cord, so as to support it, and gently compress it on all sides. 
 
 The spinal cord is not suspended freely in the vertebral canal, but is attached on each 
 side by a ligament called the ligamentum denticulatum. 
 
 The Ligamentum Denticulatum. 
 The ligamentum denticulatum (c c, fig. 267), so called from the toothlike prolongations 
 Fig. 267. which proceed from its outer border, is an extremely slen- 
 
 der, fibrous band, which runs along the side of the spinal 
 cord, and adheres to the proper sheath of the cord by its 
 inner border, which is very thin. The outer edge is free, 
 thicker than the inner portion, and gives off certain tooth- 
 like prolongations, which are attached to the dura mater in 
 the intervals between the canals formed by that membrane 
 for the spinal nerves : the first denticulation of this liga- 
 ment, which may be regarded as its origin, is very long, and 
 is found opposite the margin of the foramen magnum, be- 
 tween the vertebral artery and the hypoglossal nerve ; the 
 last, which is the twentieth or twenty-first, forms the ter- 
 mination of the ligament, and corresponds very nearly to 
 "^3 the lower extremity of the spinal cord. The form, thin- 
 
 ness, and length of these toothlike processes are subject to much variety. 
 
 The ligamentum denticulatum is evidently fibrous, and cannot be regarded, as Bonn 
 imagined, as a prolongation of the arachnoid.^ 
 
 The ligamentum denticulatum appears to answer the twofold use of assisting in fixing 
 the spinal cord, and of separating the anterior (a) from the posterior {b) roots of the spi- 
 nal nerves. 
 
 The Dimensions of the Spinal Cord. 
 
 Tlie length of the spinal cord in the adult is from fifteen to eighteen inches. Its cir- 
 cumference is twelve lines at the thinnest part and eighteen at the thickest. But it is 
 of much less importance to determine the actual dimensions of the spina] cord than to 
 estimate its relative size as compared with that of the brain, or in reference to the ca- 
 pacity of the vertebral canal, or than to examine the differences in size which it pre- 
 sents at different parts of its extent. 
 
 If the size of the spinal cord be compared with that of the whole body, throughout the 
 series of vertebrated animals, we shall perceive that it always bears a direct ratio to the 
 vital activity of the animal. Thus considered, the spined cord is small in fishes and rep- 
 tiles, and large in birds and the mammalia. 
 
 Size and Weight of the Spinal Cord compared with the Size and Weight of the Brain. — It 
 was while studying the spinal cord and the brain in serpents and fishes that Praxagoras, 
 as quoted by Galen, originated the idea that the brain was a production of the spinal cord. 
 All the old anatonusts, on the other hand, who studied the brain and cord in man, in 
 mammalia, and in birds, regarded the medulla spinalis as a prolongation or appendix of 
 the brain (tanquam cerebri effusionem, Rufus) ; indeed, it was for a long time consid- 
 
 * The first description of the spinal cord which is worthy of notice was given by Huber (J. Huber, De Me- 
 duUd Spinali, Goeltingae, 1741) ; it served as the basis for the works of Haller {Elem. Physiol., torn, iv., sect. 
 1) ; of Mayer, who published a l)eaTitiful plate of it in 1779; and perhaps of Alexander Monro, Secundus (06- 
 servations on the Structure and Functions of the Nervous System, 1783). Scsmmering-, Reil, and Gall, who 
 so successfully studied the other parts of the nervous system, have noticed the spinal cord in a superficial man- 
 ner. Chaussier (De V Encephale en general et en particulier) ; Keuffel, in his inaugural dissertation {De Me- 
 dulld Spinali, 1810, dedicated to Reil, his preceptor) ; and Rolando {Richerche Anatomiche sulla Strutlura dei 
 Midollo Spinale, Torino, 1824), have supplied many of the deficiencies in our knowledge of this part. There 
 is a good description of the medulla in M. OUivier's work upon the diseases to which it is subject. 
 
 t The position of the nervous axis behind the alimentary canal constitutes one of the great differences whicli 
 exist between the nervous system of the vertebrated and the invertebrated animals ; in the latter, the nervous 
 system lies below, i. «., in front of the alimentary canal. 
 
 t It is idle to inquire whether it should be considered a prolongation of the dura mater, or an eztension at 
 the neurilemma, or a proper ligament. 
 
DIMENSIONS OP THE SPINAL OORD. 695 
 
 ered that the medulla was the principal nerve in the body, summus in corpote humano tier- 
 vus. In the present day, anatomists have returned to the opinion of Praxagoras, and 
 the spinal marrow is generally regarded (Reil, Gall, Tiedemann) as the fundamental 
 part of the nervous system, and that the brain is merely a production, an appendage, or 
 an expansion of the cord. I shall not here enter into these purely speculative questions 
 of production or emanation, origin, and relative importance, for the spinal cord no more 
 produces the brain than the brain produces it. 
 
 Soemmering has shovni that, in man, the spinal cord is smaller in proportion to the 
 size of the encephalon than in the lower animals ; and of this there can be no doubt ; but 
 it does not follow that the lower animals have a larger spinal cord than man in propor- 
 tion to the size of their bodies : on the contrary, from actual observation, I should say 
 thiit, if we except birds, man has a relatively larger spinal cord than any other animal. 
 Compare, indeed, the medulla of the horse, or of the ox, with that of man, and it will at 
 once be found that the last is the largest and heaviest in proportion to the rest of the 
 body. 
 
 According to Chaussier, the weight of the spinal cord in the adult is from the nine- 
 teenth to the twenty-fifth part of that of the brain, and in the newborn infant about the 
 fortieth part. According to Meckel, this last is also the proportion in the adult. It must 
 be remembered, however, that Meckel examined the cord when deprived of its proper 
 membrane, and, therefore, after the roots of the nerves were detached from it. 
 
 Size of the Spinal Cord compared with the Capacity of the Spinal Canal. — The spinal 
 cord does not, by a great deal, fill up the vertebral canal, and a considerable interval oc- 
 cupied by fluids exists between it and the sides of the canal. What is the object of this 
 disproportion 1 and why is there any interval 1 We have already stated (see Osteol- 
 ogy) that the dimensions of the canal are in relation, not only with the size of the cord, 
 but also with the extent of motion of the vertebral column. The opinion of Vieussens, 
 that this space is intended to allow of certain movements of elevation and depression in 
 the spinal cord analogous to those which have been observed in the brain, is sufficiently 
 refuted by the fact that, although the latter organ is affected by movements synchronous 
 with the respiration and with the pulse, it still fills the cavity of the cranium. * 
 
 The length of the spinal cord does not correspond with that of the vertebral canal, for 
 the cord terminates near the first lumbar vertebra (between 20 and 21, fig. 268), while 
 the canal is prolonged into the sacrum. 
 
 The position of the lower end of the spinal cord has not been determined with the pre- 
 cision which so important a question demands. According to Winslow, it terminates 
 opposite the first lumbar vertebra ; Morgagni has seen it reach down to the second ; 
 Keuffel has observed it to descend as low as the third lumbar vertebra in one subject, 
 and to terminate opposite the eleventh dorsal vertebra in another. The discrepancy be- 
 tween various authors upon this subject depends upon individual varieties in the point of 
 termination of the cord, and upon the different acceptation of the term lower extremity 
 of the spinal cord ; some regarding the thick swollen part as the end of the cord, while 
 others include in it the tapering portion also. From some experiments which I made 
 upon this subject by thrusting a scalpel horizontally from before backward through the 
 inter-vertebral substance between the first and second lumbar vertebrae, I ascertained 
 that there are varieties in different subjects in regard to the point of termination of the 
 spinal cord, and that it was influenced by the position of the body, and by the state of 
 flexion or extension of the head and spine, but that, in general, the widest part or base 
 of the cone in which the cord ends corresponds to the first lumbar vertebra, and the apex 
 of the cone to the second. 
 
 During the early periods of foetal life, the cord descends as low as the sacrum ; but in 
 foetuses at the full time, I have never found so marked a difference as has been descri 
 bed by some modem anatomists. + 
 
 Differences in the Size of the Spinal Cord at different Points of its Extent.— The spinal 
 cord is not of uniform dimensions throughout its whole extent : it is much enlarged at 
 
 * From several experiments which I have made upon this subject, it appeared that the spinal fluid seen (con- 
 fined in its membranes) in the cervical region, between the occipital bone and the axis, was agitated by move- 
 ments synchronous with the pulse and the respiration ; but that, when this fluid had been evacuated, the spi- 
 nal cord did not move at all. I have examined with the greatest care the tumours existing in the lumbar re- 
 gion in infants afilicted with spina bifida ; I could never detect in them any movement corresponding with the 
 pulse, but the movement of respiration exerted a manifest influence upon them ; thus, when the sac was emp- 
 tied by compression, the cries of the infant, excited by pain, were almost instantly followed by extreme ten- 
 sion of the sac. As the spinal cord is not affected by the great arteries at the base of the brain, it cannot par- 
 ticipate in the slightest degree in those movements which are observed in the spinal fluid at every puise of the 
 heart, and which are communicated to that fluid by the cerebral arteries. 
 
 t The spinal cord is capable of elongation and retraction ; it is elongated during flexion, and returns to its 
 original condition during extension of the vertebral column; the difference between the two states appears to 
 mo to be from an inch to fifteen lines. 
 
 In the body of an infant at the full time, which was affected with spina bifida in the sacral region, and died 
 a short time after birth, the spinal marrow descended as low as the sacrum, and there was no cauda equina 
 Malacarne had already observed a similar fact ; this peculiarity depends not upon an arrest of development in 
 the cord, but upon adhesions contracted by it at an early period of foetal life. — (See Auat. Pathol., liv. xvii., 
 art Spina Bifida.) vi., 
 
NEUROLOGY. 
 
 its upper part, opposite the basilar groove, where it constitutes the superior or occipital 
 rachidian bulb, or the medulla oblongata (a) ; it becomes narrowed immediately after hav- 
 ing emerged from the foramen magnum. This constriction, which is named the neck of 
 the rachidian bulb, is regarded by many anatomists as the commencement of the spinal cord. 
 
 Another oblong enlargement, extending over a much greater length than the prece- 
 ding, and named the middle, cervical, or brachial rachidian bulb, or cervical enlargement (6), 
 commences opposite the third cervical, and terminates opposite the third dorsal vertebra. 
 
 The spinal cord again becomes considerably contracted from the first to the eleventh 
 dorsal vertebra, and then presents a third enlargement of less extent than either of the 
 other two, constituting the inferior lumbar or crural rachidian bulb, or lumbar enlargement 
 (c) ; it then immediately tapers like a spindle, and terminates in an exceedingly slender 
 semi-transparent cord, which has a fibrous, filiform aspect, is concealed among the 
 nerves of the cauda equina {d), and is always accompanied by a vein. This cord may 
 be distinguished from the surrounding nerves by its being situated in the median line, 
 and by its thinness, its fibrous character, and its termination. It may be traced as far 
 as the base of the sacrum, when it terminates in the dura mater. 
 
 In some cases the narrow portion of the inferior rachidian bulb is bifurcated, but the 
 two branches of the bifurcation terminate in a single fibrous cord. Huber, Haller, and 
 Stemmering describe the spinal cord as terminating below by two small globular enlarge- 
 ments, of which the superior is oval, and the inferior conical. They have evidently mis- 
 taken an exception for the rule. 
 
 These three enlargements of the spinal cord constitute a totally different structure 
 from that admitted by Gall, who, comparing with Haller the spinal cord of man, and the 
 vertebrata generally, to the double series of ganglia in annelida and insects, maintained 
 that there are as many enlargements of the cord as there are pairs of nerves. A strict 
 examination into facts is completely at variance with this opinion, for even in the foetus, 
 the temporary conditions of which so frequently resemble the permanent state of the 
 lower animals, we find no trace of this series of enlargements. An erroneous inference, 
 together with the aspect of the cord when surrounded by its nerves, have misled this 
 celebrated physiologist, who should have sought for the representatives of the ganglia of 
 insects, not in the spinal cord itself, but in the series of ganglia on the spinal nerves.* 
 
 The existence of the three enlargements of the spinal cord above described is in ac- 
 cordance with two general laws relating to the nervous system, viz., 1. That the size 
 of the spinal cord is in proportion to the size and number of the nerves which arise from 
 and terminate in it, and to the functional activity of the organs to which those nerves 
 are distributed ; and, 2. That the exercise of sensibility is connected with larger nerves 
 than that of muscular contractility. 
 
 Now the most numerous and the most important nervous communications take place 
 opposite those three enlargements. The nerves of the lower extremities correspond 
 with the inferior or lumbar enlargements ; those of the upper extremities, with the mid- 
 dle one ; and the nerves of respiration, the nerves of the tongue, and a part, or perhaps 
 the whole of the nerves of the face, with the superior enlargement. 
 
 The cervical enlargement, which corresponds to the upper extremities, is certainly 
 larger than the lumbar one, but this is because the upper extremities possess a greater 
 degree of muscular activity than the lower, and also because they are the organs of touch. 
 
 This explanation is completely justified by comparative anatomy, and is applicable 
 also to the differences in the length of the spinal cord .- thus, it is found that in the dif- 
 ferent species of animals, the length of the spinal cord depends, not upon that of the 
 vertebral canal, nor upon the presence or absence of a tail, but is proportionate to the 
 muscular energy, and to the degree of sensibility. Desmoulins, a young anatomist, too 
 soon lost to science, hsis established this fact by incontrovertible evidence.! 
 
 The Form, Direction, and Relations of the Spinal Cord. 
 The spinal cord has the form of a cylinder flattened in front and behind (D, fig. 269). 
 
 * These supposed enlargements are not to be found even in the spinal cord of the calf, which Gall too* as 
 offering the type of this structure. The committee of the institute likewise failed to discover them in the dog, 
 the pig, the deer, the roe-buck, the ox, and the horse, in which Gall asserted that he had found them. The 
 beautiful researches of Tiedemann into the development of the spinal cord have completely overthrown Gall's 
 opinion, which rested merely upon unsubstantiated analogies. 
 
 [It may be remarked, that though Gall's anatomical statement is not correct, his view as to the analogy is 
 more in accordance with received doctrines than that of the author.] 
 
 t The spinal cord of birds furnishes a striking pioof of the law which presides over the development of this 
 part of the nervous system. There are no movements performed by animals which require greater force and 
 agility than those observed in the act of flying. It is therefore not astonishing to find that the spinal cord is 
 enlarged opposite the nerves which go to the muscles of the wings. It would be supposed that the portion of 
 the cord which corresponds to the lower extremities should be much smaller than that corresponding to the 
 upper, but yet the inferior enlargement is equal to the one for the wings, because, according to a more inge- 
 nious than probable idea, the lower extremities are the organs of touch in birds. 
 
 The spinal cord of the tortoise most clearly confirms the law which we have adopted from Desmoulins. The 
 sort of calcareous and homy case in which the trunk of that animal is enclosed is destitute of all power of 
 motion or sensation ; and it is found, the enlarged part of the spinal cord which corresponds to the upper ex 
 tremities is united to that which corresponds to the lower by an extremely slender portion. 
 
NEURILEMMA OP THE SPINAL CORD. 697 
 
 It exactly corresponds in direction with the vertebral column, every deviation of which 
 it closely follows ; and it is an interesting fact, that it escapes compression, even in an- 
 gular curvatures of the spine. ' 
 
 The right and left halves of the spinal cord are perfectly symmetrical. There is less 
 symmetry between the anterior and posterior halves, and still less between the upper 
 and lower halves of the cord. 
 
 The spinal cord is divided by anatomists into a body and extremities. The body of the 
 cord requires to be examined, both when covered by its proper sheath, and after the re- 
 moval of that membrane. 
 
 The Body of the Spinal Cord enveloped in its Proper Membrane. 
 
 The surface of the cord everywhere presents certain transverse folds, united by oth- 
 ers running obliquely, so as to form zigzag folds, which were compared by Huber to the 
 rings of a silkworm, and regarded by Monro as so many small articulations ; these folds 
 are situated in the sheath of the cord, and are precisely analogous to those which have 
 been noticed in the tendons during relaxation of the muscles, and those which we shall 
 hereafter have to describe as appearing in relaxed nerves ; they are effaced by exten- 
 sion of the spinal cord, and are reproduced when it resumes its original length. 
 
 The existence of these folds prevents that stretching of the cord which would other- 
 wise occur in the different movements of the vertebral column. They endow the cord 
 with a certain degree of elasticity. 
 
 The spinal marrow presents for consideration an anterior, posterior, and two lateral 
 surfaces. 
 
 The anterior surface presents in the median line a fibrous band, which runs along the 
 entire length of the medulla, and conceals the anterior median groove. 
 
 The posterior surface, at first sight, presents no trace of a median groove. Many 
 anatomists, therefore, and especially Huber, have denied its existence ; but with a little 
 care we may detect a very delicate line which indicates the situation of the posterior 
 median groove, to which we shall presently advert. On each side of the median line, 
 both on the anterior and posterior surfaces of the cord, are seen the roots of the spinal 
 nerves (1 to 31, fig. 268), which are arranged in four regular lines down the cord, and are 
 divided on either side into the anterior {a, fig. 267) and the posterior {b) roots. The dif- 
 ferences which we shall hereafter describe as existing between these two sets of roots, 
 both in their number, size, and mode of attachment, enable us, at first sight, to distin- 
 guish between the anterior and posterior surfaces of the cord. 
 
 If these roots be detached, it will be seen that their place of insertion is marked by a 
 series of depressed points, which together constitute two furrows both upon the front and 
 back of the cord, accurately described by Chaussier under the name of the collateral fur- 
 rows of the spinal cord. We cannot deny the existence of the posterior collateral fur- 
 rows, but I do not think that the anterior collateral furrows should be admitted. 
 
 The sides of the spinal cord are rounded, and narrower than either tlie anterior or the 
 posterior surface : there is no furrow upon these sides, as described by some authors. 
 The two ligamenta denticulata are attached to them. 
 
 "We must next examine the proper membrane of the cord, or the rachidian pia mater, 
 which we shall name the neurilemma of the cord, from its analogy to the neurilemma of 
 the nerves ; we shall then describe the cord itself 
 
 J^eurilemma of the Spinal Cord, or Rachidian Pia Mater. 
 
 Dissection. — It is difficult to separate the rachidian pia mater from the cord, in the 
 greater number of subjects, on account of the softness of the cord itself, and of the rapid 
 changes which it undergoes after death. In order to succeed in doing so, it is advisable 
 to select the body of a person who has died from an acute disease or from an accident. 
 The spinal cord of new-born infants is more fitted for this purpose than that of adults, not 
 only from its relatively greater density at that period of life, but also from its adhesion 
 to the neurilemma being less firm. 
 
 In the bodies of infants, after making a circular incision through the neurilemma op- 
 posite the medulla oblongata, the sheath may be drawn downward, in the same manner 
 as an eel is skinned, or a stocking drawn off by turning it inside out. When the sheath 
 is more adherent to the cord, it must be very carefully divided along each side of the 
 median furrows, and then detached by breaking down, with the handle of a scalpel, the 
 cellular and vascular prolongations which connect it with the cord. 
 
 Although the proper covering of the brain, or cerebral pia mater, consists essentially of 
 an interlacement of vessels, the proper sheath of the spinal cord, or rachidian pia mater, 
 is a fibrous, and, therefore, a strong membrane, which supports and protects that part of 
 the cerebro-spinal axis, as the neurilemma does the nerves. 
 
 The external surface of this membrane is surrounded with a network of remarkably 
 tortuous bloodvessels ; and vessels are also found in its substance. The spinal cord is 
 visible through this semi-transparent membrane, which is naturally of a pearly-white 
 
 4T 
 
698 NEUROLOGY. 
 
 colour, but IS sometimes dull, yellowish, blackish, or even covered with black spots, es- 
 pecially in the cervical region.* 
 
 This surface of the rachidian neurilemma is also rough, being covered with small cel- 
 lular and fibrous filaments which float under water, and are the remains of small fibrous 
 cords, which extended from the neurilemma to the arachnoid. 
 
 The internal surface of the neurilemma adheres to the spinal cord by a great number 
 of cellular and vascular prolongations, which form areolae or meshes in its interior, and 
 which have been well described and figured by Keuffel. 
 
 Along the anterior median furrow, the neurilemma sends off a prolongation, which, en- 
 tering that furrow, lines one of its walls, and is then reflected at its bottom, so as to hne 
 the other waU ; within the substance of the duplicature thus formed, the bloodvessels 
 penetrate. A simple prolongation of the neurilemma, of extreme tensity, also enters 
 into the posterior median furrows, and forms a line of separation between the two pos- 
 terior halves of the spinal cord. 
 
 The neurilemma is prolonged below the lower extremity of the spinal cord as a fibrous 
 filament, very well described by Huber, which is inserted into the base of the coccyx. 
 
 This filament the older anatomists regarded as a nerve, and named it the nervus impar ; 
 it is very strong considering its thinness ; it is always tense, and appears to be intended 
 to fix the lower end of the spinal cord ; in this respect serving a similar purpose with the 
 ligamentum denticulatum. Its upper part is hollow, and is filled with a gray and ex- 
 tremely soft substance. 
 
 The ligamentum denticulatum, which has been considered as a prolongation of the prop- 
 er membrane of the cord, is attached to the external surface of this membrane ; and the 
 proper neurilemma of each nervous filament is also given off from this surface. 
 
 Monro has stated that a soft layer of gray substance covers the white substance of the 
 spinal cord, and separates it from its neurilemma, but such a layer does not exist. t 
 
 While the other membranes of the spinal cord are much larger than the part which 
 they have to invest, the neurilemma of the cord is exactly moulded upon it, and even 
 exerts a certain degree of pressure upon it, as is evident from the manner in which the 
 substance of the cord protrudes when this covering is punctured ; this compression oc- 
 casions the apparent consistence of the cord when it is enveloped in its sheath ; a con- 
 dition which contrasts so strongly with its softness when that sheath has been removed. 
 
 This compression, as well as the absolute inextensibility of the neurilemma, accounts 
 for the rarity of effusions in the cord, and also for the fatal effects of even the slightest 
 effusions within its substance when they do occur. 
 
 Structure. — The proper membrane of the cord is essentially fibrous ; nor has it any 
 claim to be termed a vascular membrane (tunica vasculosa, Soemmering). Its component 
 fibres interlace in every direction, but the majority of them are longitudinal. It is quite 
 evident that the vessels which ramify upon its surface, and afterward penetrate it, do 
 not belong to the membrane itself. 
 
 Uses. — The neurilemma is essentially a protecting structure ; it constitutes the frame- 
 work of the spinal cord, and serves, at the same time, as a support for the nutritious ves- 
 sels of that organ ; in this latter respect it has been compared to the pi a mater of the 
 brain. The transition from the spinal into the cerebral portion of the pia mater takes 
 place gradually. The fibrous character of this tunic diminishes upon the medulla oblon- 
 gata and tuber annulare, and is entirely lost opposite the peduncles of the brain ; while 
 its vascular character, on the contrary, becomes gradually more and more marked as it 
 passes from the cord towards the brain. 
 
 It has been stated that the neurilemma is the secreting organ of the spinal cord ; one 
 might as well say that the testicle is secreted by the tunica albuginea, and the heart by 
 the pericardium. 
 
 The Body of the Spinal Cord deprived of its J^eurilemma. 
 
 When the neurilemma of the cord is removed, the spinal nerves are also taken away. 
 We shall hereafter have to inquire whether this fact should lead us to conclude that 
 the nerves do not enter into the substance of the cord, but merely come into contact 
 with it. 
 
 We would observe, however, in this place, that the posterior roots of the spinal nerves 
 arise in a perfectly regular line, while the anterior roots come off irregularly from differ- 
 ent points of the corresponding medullary column, t 
 
 The Anterior Median Grocwe and the Commissure. — The anterior median groove, or fissure 
 
 * These different shades of colour are much more common in certain animals, in the sheep, for example, 
 than in man ; they result from the deposition of a colouring matter, and are in no way connected with any 
 recent or previous morbid action. 
 
 t In several subjects, I have most distinctly seen a very thin yellowish layer over the medulla oblongata, 
 which dipped between the pyramidal bodies, and filled up the shallow groove which separates the olivary from 
 the pvramidal bodies. 
 
 X This mode of origin of the anterior roots is perfectly distinct in the spinal cord of the futus or new-bom 
 infant ; up to this period, the tract from which the anterior roots arise is still formed of gray substance. Th« 
 roots, which are white, emerge fmm this gray tract, and when the neurilemma is removed, their small, white, 
 ruptured ends which remain may be traced into the substance of the cord. 
 
THE SPINAL CORD DEPRIVED OF ITS NEURILEMMA. 
 
 Fig. 268. 
 
 (Jig. 26R ; f, fig. 269, D), penetrates to about one 
 third of the thickness of the cord. At the bottom 
 of the groove, which is occupied by a prolongation 
 of the neurilenuna and a great number of vessels, 
 is seen an extremely thin white layer, perforated 
 with foramina, which is named the anterior com- 
 missure (commissure longitudinale, Chaussier). The 
 foramina in this structure are intended for the trans- 
 mission of tufts of vessels, which enter the sub- 
 stance of the cord. The alternate arrangement of 
 these foramina greatly increases the difficulty of 
 drawing out the vessels, and gives to the commis- 
 sure the appearance of being formed by interlacing 
 fibres ; and, in fact, several anatomists have not 
 only admitted such an interlacement, but have ex- 
 pressly stated that it was produced by the spinal 
 nerves themselves.* 
 
 According to Gall and Spurzheim, the bundles of 
 which this commissure consists are directed trans- 
 versely, and are fitted into each other like the mo- 
 lar teeth ; but I repeat, that the most careful ex- 
 amination demonstrates nothing in the commissure, 
 besides a white lamella, perforated for the transmis- 
 sion of bloodvessels. 
 
 The Posterior Median Groove. — The posterior me- 
 dian groove or fissure (a) not only exists, but is 
 much deeper than the anterior one. Its narrow- 
 ness, and the tenuity of the membranous prolon- 
 gation which enters it, have alone concealed it from 
 the observation of anatomists ; there is no white 
 band analogous to that of the anterior median fis- 
 sure at the bottom of this fissure, but the gray sub- 
 stance of the commissure is all that is seen. 
 
 As there are two median furrows, it follows that 
 there are really two distinct spinal cords, connected 
 together by an extremely thin band or commissure. 
 
 The Furrows opposite the Posterior Roots of the 
 Nerves, or the Posterior Lateral Furrows. — Immedi- 
 ately to the outer side of the line of origin of the 
 posterior roots of the spinal nerves, there is a gray- 
 ish line or furrow (i), which extends the whole 
 length of the cord. If a stream of water be allowed 
 to fall upon this line, the continuity of the cord is 
 soon destroyed, and the water penetrates to the 
 centre of the organ. 
 
 But there are no true fissures in these situations 
 analogous to the anterior and posterior median fur- 
 rows. The separation is effected by the destruc- 
 tion of the gray substance, a prolongation of which 
 reaches to the surface of the cord opposite these 
 points. We shall, nevertheless, suppose these fur- 
 rows to exist in accordance with the views of Soem- 
 mering and Rolando, who divided each half of the 
 spinal cord into two columns : a posterior column, 
 consisting of that portion (e) which is comprised be- 
 tween the posterior median furrow (a) and the posterior roots (i) ; and an antcro-lateral 
 column, including all that portion (rf) which is situated between the anterior median fur- 
 row (/) and the supposed posterior lateral furrow (r). We must also admit, with Haller, 
 Chaussier, Gall, and Rolando, a third column on each side ; these may be called the pos- 
 terior median columns, and are continuous with the projecting bundles which form the 
 borders of the calamus scriptorius, and which are each limited externally by a slight 
 groove. These small and exceedingly narrow columns, the existence of which is admit- 
 ted by most anatomists in the cervical region only, are prolonged through the whole ex- 
 tent of the spinal cord. 
 
 Is there an anterior lateral furrow ? If the line on the outer side of the attachment of 
 the anterior roots of the spinal nerves be closely examined, the appearance of a furrow 
 is seen along the whole of the cord. But if water be allowed to fall upon that line, it is 
 
 * There is uo physiological or pathological fact which demonstrates the crossing 
 nal cord. 
 
 eiTect of lesions of the spi 
 
700 NEUROLOGY. 
 
 found that there is no fissure or furrow properly so called, and that the jet of water has 
 no more effect upon this line than on the adjoining parts ; we are therefore led to reject, 
 with Rolando, both these anterior lateral furrows and the lateral tracts described by 
 Chaussier, which would be bounded in front by the furrow of the anterior roots, and be- 
 hind by that of the posterior roots ; these lateral tracts have, nevertheless, become cele- 
 brated, since so much importance has been attached to them by Sir C. Bell and Bellin- 
 geri as the lateral columns of the spinal cord. 
 
 From what has been stated above, it follows that each half of the cord is composed 
 of two columns, a posterior and an antero-lateral, and as an appendage to the posterior 
 column, of a small column, which forms the border of the posterior median furrows. 
 
 Internal Structure of the Spinal Cord. 
 The following results regarding the structure of the cord have been obtained by va- 
 rious modes of investigation : by making sections of it ; by acting upon it with a stream 
 of water ; by hardening it in alcohol and dissecting it ; by studying its development ; 
 and, lastly, by a reference to its comparative anatomy, which appears to be necessary to 
 complete the knowledge acquired by the other means of investigation. 
 
 Sections of the Cord. 
 ' It appears, from an examination of the external structure of the spinal cord, that it 
 consists of two white, juxtaposed cylinders ; that the surfaces by which these cylinders 
 correspond are flat, closely in contact, and united together by a median commissure ; 
 and that each of them may be divided into two columns, the one posterior and smaller, 
 of which the posterior median column is only an appendage; the other, antero-lateral, 
 which forms two thirds of the circumference of the cylinder. 
 
 Horizontal Sections. — If various horizontal sections be made through different parts of 
 Fig. 269. t^^ spinal cord, we see that each half consists of a cylinder of white 
 substance, containing gray substance in its interior (see Jig. 269, D) ; 
 that the median commissure is composed of a white layer {white commis- 
 sure) and a gray layer (gray commissure) ; and that in each section the 
 gray matter has a tolerably close resemblance in form to the letter x, the 
 two halves or curves of which are joined in the middle by a horizontal 
 line, while the extremities of the curves are directed towards the ori- 
 gins of the anterior and posterior roots of the nerves. The posterior 
 I B extremities reach much nearer to the surface than the anterior. We 
 perceive, also, in these different sections, that the circumference of the 
 cord is not perfectly regular, but is somewhat sinuous, as we shall pres- 
 ently mention. 
 
 The size of the central gray mass in each half of the spinal cord, the 
 length and thickness of the prolongations or points, which it sends off 
 towards the anterior and posterior roots, and, lastly, the thickness of 
 the gray commissure, present many varieties, according to the place of 
 section ;* and hence there is a discrepancy between different authors 
 as to the appearances of this section. Thus, Huber compared the sec- 
 tion of the gray matter to an os hyoides ; Monro, to a cross ; Keuffel, to 
 four rays converging towards a central point. 
 Rolando has given figures of sections of the cord at every part of its length. 
 From sections of the cord the general fact is established, that the white substance en- 
 closes the gray matter. The thin layer of gray matter on the surface of the cord ad- 
 mitted by Monro has been justly rejected by all anatomists. The relative situation of 
 the two substances in the cord, which is the reverse of what is observed in the brain, 
 has attracted the attention of anatomists, and various explanations, of greater or less 
 ingenuity, but all hypothetical, have been given of this fact. 
 
 According to Rolando, there are two kinds of gray matter in the cord, one occupying 
 the anterior, and the other the posterior half of the cylinder ; and these two halves are 
 fitted into each other by a series of indentations, like the bones of the cranium. 
 
 I have never been able to convince myself of the existence of these two kinds of gray 
 matter, but I have distinctly observed the denticulated appearance of the circumference 
 of the gray matter, which indicates that the gray and white matter mutually penetrate 
 into each other. 
 
 The colour of the gray substance varies considerably. In some subjects it is whitish, 
 and can only be distinguished from the white matter by its softness, its vascularity, and 
 its not having a fibrous structure. The younger the individual, the more marked is the 
 difference in colour between the two substances. 
 
 The two substances appear also to differ in their relative proportions in different in- 
 dividuals. Keuffel has ascertained that the gray matter is more abundant in man than 
 
 * I would recommend five sections of the cord, which appear to rae to give a very accurate notion of its in- 
 ternal structure : the first should be immediately below the decussation of the pyramids ; the second through 
 the middle of the brachial enlargement ; the third through the dorsal constricted part ; the fourth through the 
 middle of the lumbar enlargement ; and the fifth near the apex of the cone formed by the lumbar enlargement. 
 
INTERNAL STRUCTURE OP THE SPINAL CORD. ^'Wl 
 
 in the lower animals ; and this fact would account for the pre-eminent sensibility of the 
 human subject, in accordance with the view of BeUingeri, who considers that the gray 
 matter is the seat of sensation. 
 
 These horizontal sections enable us not only to determine the relative position and 
 proportions of the white and gray substances, but also to distinguish the superficial fur- 
 rows from those which really enter into the cord ; the existence of these columns in the 
 spinal cord, which have already been described, is in this way fully established. 
 
 Vertical Sections. — The most important of these is one made from before backward in 
 the median line, so as to separate the two halves of the cord. Each of these halves may 
 then be unfolded like a riband, on the inner surface of which the gray matter forms a 
 thin layer. 
 
 A transverse vertical section, through the centre of the cord, displays the mode of 
 origin of the anterior and posterior roots of the nerves. 
 
 Examination of the Spinal Cord under a Stream of Water. 
 
 The different sections above mentioned expose the general internal arrangements of 
 the cord rather than its actual structure. 
 
 Until lately, authors had regarded the spinal cord as consisting of a semi-fluid pulp, 
 which oozed out when the neurilemma was divided. Several had said, incidentally, and 
 without distinguishing between the white and the gray substance, that the cord had a 
 fibrous structure, and that its fibres were directed longitudinally. Gall supposed the 
 cord to consist of a series of ganglia, arranged one upon the other ; but it is now gener- 
 ally admitted that the white matter is fibrous, and that its fibres have a linear arrange- 
 ment ; and this is clearly shown by examining this organ by means of a stream of water, 
 the force and size of which may be varied at will. 
 
 When directed upon the surface of a vertical section, made from before backward 
 down the middle line, the stream of water penetrates the substance of the cord through 
 the gray commissure, breaks down the central gray matter, and spreads the cord out 
 like a riband, from which it is very difficult to wash off all the gray matter. When 
 treated in this way, each half of the cord is almost immediately subdivided into two col- 
 umns, and if the stream of water be now directed upon the internal surface of the col- 
 umns themselves, they may be separated into a great number of wedge-shaped vertical 
 lamellae, directed from the circumference to the centre, the thick external backs of which 
 are turned towards the surface, and the thin internal edges towards the centre of the 
 cord. Now, as all these lamellae are not of equal depth from back to edge, their internal 
 edges reach to different distances from the centre ; hence the denticulated appearance 
 of the circumference of the gray matter in a section ; and hence, also, the mistake of 
 Rolando, in describing the white matter as formed by a medullary layer, folded a very 
 great many times upon itself* 
 
 According to my observations, each lamella is completely independent of the adjacent 
 ones ; and pathological anatomy fully confirms this observation, by showing that one only 
 may be altered or atrophied, while the others remain unaffected. 
 
 If the action of the stream of water be continued, these medullary lamellae are decom- 
 posed into very delicate juxtaposed filaments, which extend along the entire length of 
 the cord ; they are all independent of each other, and are merely connected by cellular 
 tissue and some vessels. 
 
 The structure of the spinal cord is therefore filamentous or fasciculated ; its filaments 
 are almost perfectly identical with those which constitute the proper substance of the 
 nerves. Each filament in the cord traverses its entire length, as each nervous filiiment 
 extends along the whole nerve. 
 
 The very important inference to be drawn from these facts is the independence, not 
 only of each lamella, but, I may venture to say, of each filament, t 
 
 * Rolando has even counted these folds : he numbers fifty in the spinal cord of the ox, opposite the origin 
 of the sixth pair of sacral nerves, and about thirty opposite the third pair of sacral nerves ; both of these ob- 
 servations refer to the anterior columns only, for in the two figures which he gives of them the posterior col- 
 umns appear to have no folds. Rolando made his observations upon spinal cords which had been macerated 
 eil'jcr in pure water or in salt and water. 
 
 t [The microscopic structure of the white and gray substances of the brain and spinal cord has been inves- 
 tigated by Fontana, Ehrenberg, Weber, Remak, Valentin, and others. The fibres of the white matter consist 
 of coherent threads of a soft, semi-transparent, tenacious substance, enclosed in an extremely delicate homo- 
 geneous or structureless sheath, which is very difficult of detection : these fibres are smaller than those of the 
 nerves ; they differ much in size, but each of them is of uniform diameter throughout ; when submitted to 
 the slightest pressure during examination, they have a remarkable tendency to become varicose or beaded, a 
 property which is peculiar to them and to the fibres of the olfactory, optic, and auditory nerves, which also re- 
 semble the fibres of the brain in other respects. 
 
 The gray matter of the brain and spinal cord consists of large reddish gray globules, containing a nucleus 
 and one or more nucleoli, and having spots of pigment upon them, in situations where the gray matter is dark- 
 er than usual. Surrounding and attached to these globules there are minute jointed fibres, which are marked 
 at intervals with granules (nuclei) ; by Ehrenberg these jointed fibres were considered to be of the same na- 
 ture as the fibres of the white matter, differing from them only in size ; by Miiller and Schwann they are re- 
 garded as organic nervous fibres, resembling those found in such abundance in the sympathetic nerves and 
 ganglia ; while by Valentin and others they are supposed, not only in the brain, but also in the ganglia and 
 nerves, to be the filaments of a delicate cellular tissue. 
 
 The mode in which the white fibres of the brain and spinal cord end in the gray substance is not well made 
 
I9|tt NEUROLOGY. 
 
 Examination of the Spinal Cord hardened in Alcohol. 
 When deprived of its humidity by alcohol, the spinal marrow becomes very firm, ex- 
 tensible, and elastic. Its filamentous texture becomes very apparent, and the filaments 
 themselves, which, from the contraction of the cord, are flexuous, may be separated 
 from each other, either by the handle of the scalpel, or by slight traction. I have not 
 seen that interlacement of the fibres of the cord which is figured in the beautiful plates 
 of Herbert Mayo, and which, in my opinion, is only apparent, and is produced by drawing 
 the parts under examination in different directions. 
 
 The Cavities or Ventricles of the Spinal Cord. 
 
 Several anatomists are of opinion that there is a canal in each half of the spinal cord.* 
 
 Morgagni has slightly alluded to its existence, which he had not leisure to trace for a 
 greater extent than about five fingers' breadth, t 
 
 Gall relates that, in examining the body of an infant 8iffected with spina bifida, he cut 
 transversely through the cord, and found that it contained two canals, which he traced 
 into the substance of the medulla oblongata and tuber annulare, beneath the tubercula 
 quadrigemina, and as far as the optic thalami, where they terminated in a pouch as large 
 as an almond.t 
 
 It is certain that, up to the fourth month of foetal life, each half of the spinal cord con- 
 tains a canal precisely similar to that which exists in fishes ; but after this time the gray 
 matter takes the place of the gelatiniform fluid which had occupied the canal. However, 
 in one case I found the canal persisting after birth. 
 
 The Medulla Oblongata. 
 Situation. — The medulla oblongata, the rachidian bulb, or cranial enlargement, is that 
 conoid enlargement (a, fig. 268) which forms the upper part of the spinal cord, crowning 
 it like the capitsil of a column : it is situated upon the basilar groove of the occipital 
 bone, and connects the spinal cord with the cerebrum and cerebellum. It was named 
 medulla oblongata by Haller ; but it has also been called the cauda or tail of the medulla 
 oblongata, this term being derived from a comparison of the pons Varolii, the four pe- 
 duncles, and the medulla oblongata to an animal, the body of which was represented by 
 the tuber, the arms by the anterior peduncles, the legs by the posterior peduncles, and 
 the tail by the rachidian bulb. 
 
 External Conformation of the Medulla Oblongata. 
 
 The medulla oblongata is received into the deep groove on the fore part of the cir- 
 cumference of the cerebellum (see fig. 276), so that its anterior part only is exposed. 
 
 In man and the mammalia the medulla oblongata is bounded above and in front by the 
 tuber annulare or pons Varolii {a, fig. 270) ; but above and behind its limits are quite arti- 
 ficial, for it is prolonged upward beyond the pons, cis we shall presently see. Its limits 
 below are altogether arbitrary : the medulla oblongata, in fact, does not contract abrupt- 
 ly, as the term neck of the bulb, applied to its lower extremity, would seem to imply, but 
 it is very gradually narrowed, so as to become continuous with the spinal cord. 
 
 A plane, which is a tangent of the lower surface of the condyles of the occipital bone, 
 would correspond with the lower boundary of the medulla oblongata. ^ I think, however, 
 that it is more rational to fix this boundary according to the precise point where the me 
 dulla undergoes some decided modifications ; and this point is immediately below the 
 decussation of the pyramids. 
 
 The medulla oblongata is from fourteen to fifteen lines in length, nine lines in 
 
 out ; according to Valentin, they separate to admit the gray globules between them, and then unite with one 
 another so as to form loops. 
 
 The substance of the brain and spinal cord, according to Vauquelin, contains 80 per cent, of water ; its solid 
 constituents consist of albumen, stearine and elaine, phosphorus (1-5 per cent.), osmazome, some acids and 
 salts, and sulphur.] 
 
 * It is unnecessary to say, that the existence of the single central canal admitted by some authors, is quite 
 irreconcilable with the real structure of the cord. 
 
 t Adversaria Anat. ,\ol. i., p. 17. Morgagni relates that, having separated the medulla oblongata from the 
 rest of the spinal cord by a horizontal section, he saw in the substance of the cord, and for the space of about 
 five fingers' breadth (etfortasse etiam hngius siquis tunc otium habuisset ulteriorum meduUam e vertebris exi- 
 mendi), a cavity which admitted the end of the finger ; everything appeared to be in a natural state, except- 
 ing this cavity. He adds, that he had never met with so large a cavity ; which seems to imply that he had 
 seen cavities of this kind before. — Negue enim alias tantam out qua: huic accederet vidi. 
 
 t Spina bifida and hydrocephalus have no direct relation with the persistence of the canals of the spinal 
 cord ; and on this point, I can remove all the doubts expressed by Keuffel (De Medulld Spinali, 62) concerning 
 Morgagni's observation. " Forsan nos quoque," says Keuffel, "earn (scilicet medulla; spinalis caveam) inve- 
 nissemus, si medullam spinalem ex homine hydrocephalico aut spinJl l)ifid^ laborante, inquirere potuissemus. 
 Utinam hujusmodi opportunitas, si occurreret, a nemine negligatur, ut tandem de hJlc re certiores fiamus." 
 In five infants affected with spina bifida, and two who died of chronic hydrocephalus, which I examined for 
 this purpose, the spinal marrow was perfectly normal. Tiedemann regards the canals described by Gall as 
 produced by insufflation. 
 
 t) I have made experiments upon several subjects, which show that the relations of the medulla oblongata 
 to the foramen magnum vary according as the head is directly vertical, flexed, or extended ; an instrument 
 thrust horizontally between the atlas and occipital bone divides the medulla oblongata at different part* n 
 these various positions of the head. 
 
THE MEDULLA OBLONGATA, ETC. 708 
 
 breadth, and six in thickness ; it is therefore much broader and thicker than the spinal 
 cord. 
 
 The medulla oblongata is directed obliquely, like the inclined plane of the basilar 
 groove, so that it forms with the spinal cord a very obtuse angle, which projects back- 
 ward. 
 
 In shape it resembles a cone flattened in front and behind, and having its base turned 
 upward and its apex downward ; it has, therefore, four surfaces, viz., an anterior, a pos- 
 terior, and two lateral. 
 
 Anterior Surface of the Medulla Oblongata. 
 
 This surface (fig. 270) is directed downward, and is therefore named inferior by some 
 anatomists ; it is convex, and is lodged in the basilar groove of 
 the occipital bone ; it can be properly examined only after its '^' _' 
 
 neurilemma has been dissected off, which is easily done, because 
 its substance is denser than the spinal cord. 
 
 On this surface we observe a median furrow (/), into which 
 numerous vessels enter : this furrow, which is not nearly so deep 
 as the anterior median furrow of the spinal cord, with which it is 
 continuous, is interrupted by a decussation of fibres about ten si^ 
 lines below the pons Varolii (below n), and terminates above in 
 a tolerably deep fossa (le trou borgne, or foramen cacum, of Vicq 
 d'Azyr), at the point where the furrow meets the pons. Not un- 
 frequently some transverse fibres occupy the place of this median 
 furrow, in which case the anterior surface of the medulla ob- 
 longata resembles the pons Varolii ; sometimes these transverse fibres are found upon 
 only a part of the medulla oblongata. 
 
 On each side of this median furrow are seen two eminences, which seem as if mould 
 ed in relief upon the part, and which form two planes, succeeding one another like steps 
 from within outward. The two internal eminences are called the anterior pyramids ; the 
 two external are named, from their shape, the olivary bodies. 
 
 The interior Pyramids. 
 
 The anterior pyramids ( Vieussens, b b), situated on each side of the median line, and 
 to the inner side of the olivary bodies, are two white pyramidal bundles (bandes medul- 
 laires, Maiacarne), which extend through the entire length of the medulla oblongata ; 
 they project in relief upon the body of the medulla, and seem to emerge or originate 
 near its narrow portion or neck, where they separate from each other the anterior col- 
 umns of the spinal cord, from which columns they are quite distinct : at their point of 
 emergence they are closely approximated and narrow, being about a line and a half in 
 width ; they pass somewhat obliquely upward and outward, become more prominent, 
 and about three lines wide ; having reached the pons Varolii, they become rounded and 
 cylindrical, and are constricted before they enter the substance of the pons, in which we 
 shall afterward trace them. 
 
 Wniien the two pyramids are gently held apart, it is said that some transverse fibres 
 are seen passing from one to the other, along the bottom of the median furrow ; and it 
 is even stated that there is a decussation of their fibres : this, however, is only apparent, 
 and I cannot here too particularly caution the student against those illusive appearances, 
 which depend either upon the existence of foramina for the passage of vessels, or may 
 be produced by pulling about the scattered fibres in drawing the parts asunder. It wiU 
 soon be shown that there are no transverse fibres fiere, and that there is no decussation 
 of fibres at an acute angle along the whole length of the anterior pyramids, as was ad- 
 laitted by Petit, Winslow, Santorini, and others. 
 
 The two halves of the medulla oblongata are, in fact, merely applied to each other, 
 and agglutinated together. There is no decussation excepting at the point where the 
 pyramids emerge. 
 
 The Olivary Bodies. 
 Upon the anterior surface of the medulla oblongata, to the outer side of the anterior 
 pyramids, and upon a plane somewhat posterior to them, are found two white ovoid 
 bodies (corpora ovata), sometimes projecting in relief; these are peculiar to the human 
 subject, and are more prominent in the foetus and new-born infant than in the adult. 
 They were first described by Eustachius, and afterward more accurately by Vieussens, 
 who, on account of their shape, gave them the name of olivary bodies (corpora olivaria, c c) ; 
 they are much shorter than the anterior pyramids, being not more than six lines in 
 length ; they are directed obliquely downward and inward. The upper extremity of the 
 olivary body does not reach the pons Varolii, but is separated from it by a deep furrow ; 
 the lower extremity, which is less prominent than the upper, is bound down by a bundle 
 of arched fibres, the concave borders of which are directed upward (processus arciformes,e). 
 The outer border of the anterior pyramids and the series of nervous filaments which 
 unite to form the hypoglossal nerve (9, fig. 276) constitute the internal boundary of each 
 
704 
 
 'NEUROLOGY. 
 
 olivary body ; and a deep furrow, directed vertically, separates them on the outer side 
 from the inferior peduncles of the cerebellum or the restiform bodies.* 
 
 It is of importance to observe, that that portion of the olivary body which projects on 
 the outer side of the pyramid is only the external half of the olivary body, its interned 
 half being imbedded in the substance of the medulla oblongata, so as to reach behind the 
 anterior pyramid, t 
 
 The Posterior SurfcLce of the Medulla Oblongata. 
 This surface is partly concealed by the cerebellum, being received into a groove on 
 Fig. 271. its under surface, and cannot be completely exposed unless the 
 
 medulla oblongata be forcibly bent forward, or the middle part 
 of the cerebellum be divided vertically. It is then seen that the 
 cord appears to open out {t,fig. 271) opposite the upper part of 
 this surface, and to be turned inside out, so that the gray sub- 
 stance is exposed. In consequence of this separation of the 
 posterior columns of the cord, there is left between them a shal- 
 low, triangular, or V-shaped depression (;?), the bottom of which 
 is smooth, and forms the anterior wall of the fourth ventricle ; 
 Herophilus named this depression, from its appearance, the cal- 
 amus scriptorius. 
 
 A vertical median groove corresponds to the shaft of the quill ; 
 while its barbs are represented by certain white medullary lines, 
 which vary exceedingly in number, and are not symmetrical ; 
 some of these lines are lost upon the walls of the ventricle, and 
 others turn round the lateral surface of the medulla oblongata, 
 and constitute, in part, the origin of the auditory nerves. The 
 point of the pen is represented by the very acute inferior angle 
 lormed by the sides of the depression, which terminates below in a cul-de-sac, the fos- 
 settc of the fourth ventricle, also called the ventricle of Arantius. According to some au- 
 thors, at the point of the calamus is situated the upper orifice of a canal, which runs 
 through the whole length of the spinal cord ; such a canal, however, does not exist, but 
 is, in fact, produced by the means employed to demonstrate it, for example, by insuffla 
 tion, by the introduction of a probe, or by the weight of a column of mercury. A slight V 
 shaped deposite of corneous matter is constantly found inserted within the corresponding- 
 ly-shaped bifurcation of the columns of the cord : between the branches of the V is found 
 the prolongation of gray substance, which is continuous with the gray matter of the cord. 
 The medullary columns which immediately bound the calamus on each side, and which 
 result from the separation of the elements of the cord, are formed by the posterior me- 
 dian columns {e,fig. 269, B C, and _^^. 271), already described, which become slightly 
 enlarged where they separate from each other, so as to form a mammillary projection, 
 and then terminate insensibly upon the back of the restiform bodies : we shall call the 
 upper part of these columns the mammillary enlargements of the posterior median columns^ 
 and not '■^posterior pyramids. ''''% 
 
 On the outer side of these mammillary enlargements are found the restiform bodies (d, 
 fig. 269, C ; fig. 271), which, as we shall afterward describe, pass to the cerebellum, and 
 may be said to form its root ; they are also called the inferior peduncles of the cerebellum, 
 or processus a cerebello ad medullam ohlongatam. Ridley named them the restiform bodies, 
 or cord-like processes ; and others, again, call them the posterior pyramids. 
 Fig. 272. TheJjateral Surface of the Medulla Oblongata. 
 
 These present {fig. 272), in front, the olivary bodies (c), which we 
 have already seen upon the anterior surface. Behind them are the 
 restiform bodies (d) ; and, lastly, about three lines below the lower 
 extremity of each olivary body, is found an oblong projection, the 
 colour of which is intermediate between that of the white and that 
 of the gray substance : this projection is continuous with the gray 
 matter of the furrow, from which the posterior roots of the spinal 
 nerves arise ; and Rolando, who first directed attention to it, has 
 named it the ash-coloured tubercle (tuberculo cinereo). 
 
 The arched fibres, or processus arciformes {e,fig. 270), pointed out 
 by Santorini, and still better described by Rolando, are principally 
 found upon the lateral surfaces of the medulla oblongata ; they con- 
 sist of filaments of medullary substance, which vary exceedingly in 
 
 * I do not say, with some authors, that the filaments of origin of the glosso-pharyngeal and pneumogastric 
 nerves (8, fig. 270) bound the olivary bodies behind, for these filaments arise from the inferior peduncles of 
 the cerebellum, or the restiform bodies, not from the furrow between those peduncles and the olivary bodies 
 
 t In the body of a female who died at the Maternity, the left pyramidal and olivary bodies were not more 
 than half their usual width. It might have been supposed that they were atrophied ; but the patient had ex- 
 hibited no symptom indicative of so serious and uncommon a lesion. With a little attention, I could easily 
 see that the pyramid was divided into two portions, the anterior of which occupied the usual position, while 
 the posterior covered the posterior half of tlie olivary body. 
 
 I [The term posterior pyramids is, nevertheless, applied to these bodies by many modern anatomists.] 
 
INTERNAI? STRUCTURE OP THE MEDULLA OBLONGATA. 705 
 
 number and arrangement ; they appear to arise from the anterior median furrow of the 
 medulla oblongata, to turn like a girdle around the pyramidal and olivary bodies, and, 
 having reached the restiform bodies, to pass obliquely upward and outward to terminate 
 upon the sides of the restiform bodies. These arched fibres sometimes seem to be en- 
 tirely wanting ; at other times they are collected on each side into two bundles : one 
 superior, which turns round the anterior pyramid, as that body is about to enter the 
 pons ; the other inferior, which covers and circumscribes the lower extremity of the 
 olivary body. Lastly, the pyramidal and olivary bodies are not unfrequently found to be 
 completely and regularly covered by a thin layer of circular fibres : it will be presently 
 shown that these fibres dip into the anterior median furrow of the medulla oblongata, 
 and reach as far as the posterior median furrow.* 
 
 Internal Structure of the Medulla Oblongata. 
 The internal structure of the medulla oblongata should be examined by means of sec 
 tions, by the ordinary method of dissection, by separating its elements by means of a 
 jet of water, and by dissecting it after it has been hardened in alcohol or boiled in oil. 
 
 Sections. 
 
 Horizontal Sections. — Following the example of Rolando, we shall examine four sec- 
 tions of the medulla oblongata. 
 
 The first should be made immediately below the decussation of the pyramids ; the 
 second, opposite the middle of the decussation ; the third, through the middle of the oli- 
 vary bodies ; and the fourth, immediately below the pons. 
 
 The first section presents exactly the same appearances as a section of the spinal cord. 
 
 The second presents a very different arrangemeirt : the decussating bundles of the 
 pyramids are of very considerable size, and occupy the anterior two thirds of the sub- 
 stance of the medulla : their section represents a triangle having its base turned for- 
 ward, and its truncated apex backward. The gray matter is not circumscribed, as in 
 the first section, but appears to penetrate irregularly into the white substance of which 
 the remaining part of the medulla consists. The white substance itself has not the pure 
 whiteness of medullary substance ; nor does the gray matter resemble that of the rest 
 of the spmal cord, but it is of a yellowish-gray colour, and is much denser. 
 
 The third section through the middle of the olivary bodies {fig. 269, C) presents, be- 
 sides the triangular section of the pyramidal bodies (i), the serrated section of the corpus 
 dentatum (c') of the olivary bodies (c) ; it enables us to form an accurate idea of the shape 
 and size of these bodies, which extend to each side of the median line ; it shows that 
 they are directed obliquely inward and backward, and that they consist of successive 
 layers, viz., of an external white layer, of an interrupted yellowish layer, and of a sec- 
 ond white layer, which lines the inner surface of the yellowish one. It is seen that the 
 corpora dentata of the olivary bodies are interrupted, or, rather, open on the inner side 
 towards the median line, so as to admit the white fibres with which their interior is 
 filled. The waving gray line seen on these sections depends upon the yellow layer be- 
 ing frequently folded inward and outward upon itself; and from this appearance the 
 terms corpwi dentatum, or corps festonne, have been applied to the gray substance of the 
 olivary bodies. The remaining part (<£) of the medulla oblongata consists of a substance 
 which is of the colour of coffee mixed with milk, and which offers more resistance to 
 the knife than other parts of the medulla, and consists neither wholly of white matter 
 nor wholly of gray, but of a mixture of both. 
 
 The fourth section, made immediately below the pons {fig. 369, B), presents a trian- 
 gular surface, on which we remark, at each of the posterior angles, a thick white bun- 
 dle, almost as large as the posterior pyramidal body, and which will be hereafter shown 
 to constitute one of the roots of the fifth nerve : these bundles are also seen upon the 
 third section made through the olivary bodies, but they are much smaller than in this 
 section. The section of the two anterior pyramids {b) is circular at this point. The 
 centre of this section of the medulla consists entirely of a grayish- white or coffee-col- 
 oured substance {d c'), covered by a white layer. The grayish-white substance belongs 
 specially to the medulla oblongata ; the surrounding white layer is the continuation of 
 the columns of the spinal cord, t 
 
 The oblique sections display appearances corresponding with those of the horizontal 
 section. 
 
 Vertical Section. — A very interesting section of the medulla oblongata is a vertical one, 
 extending from before backward through the median line. I prefer the plan of forcibly 
 separating the two halves of the medulla to that of dividing it with a scalpel. By 
 this means it may be shown that there are in the median line of the medulla some an- 
 
 * Ought we to regard as a part of this system of arched fibres a small, slender cord which surrounds the 
 upper part of the anterior pyramids, and which in other respects has a similar arrangement to the arched 
 fibres generally % 
 
 t The medulla oblongata of a child seven or eight years old is much better adapted for the examination of 
 these sections than that of an adult or old subject, because the two substances are blended in the latter ; a 
 stream of water directed upon the sections will greatly assist the examination, by makiug the colours more 
 iistinct 
 
 4 U 
 
706 NEUROLOGY. • 
 
 tero-posterior fibres, which appear to me to vary in number in different subjects : fhesc 
 fibres (o, Jig. 274) run from behind forward through the whole antero-posterior diameter 
 of the medulla ; having reached the anterior median furrow, they pass horizontally out- 
 ward to cover the pyramids and olivary bodies, and form the arched fibres already de- 
 scribed. These antero-posterior fibres are limited below by the decussating fibres of the 
 pyramids. 
 
 Examination of the Medulla Oblongata by Dissection under a Jet of Water, and when hardened 
 
 in Alcohol. 
 
 The anterior pyramids may be separated by ordinary dissection, and a tolerably accu- 
 rate view obtained of their decussations ; and, moreover, the medulla oblongata may be 
 divided into two lateral halves, and its principal parts may then be isolated. The ex- 
 amination of the medulla when hardened in alcohol, or boiled in oil, or in a solution of 
 salt, leads to important results, by enabling us to dissect it fibre by fibre, and to trace 
 these fibres above and below their points of decussation. Together with these different 
 modes of investigation I have employed another, viz., that of acting upon the medulla 
 and its parts by a jet of water, the force and size of which is to be varied at pleasure, 
 and the drops of which insinuate themselves between the fibres and separate them from 
 each other.* 
 
 If a stream of water be directed upon the anterior pyramids, the fasciculated ar- 
 rangement of their component fibres, all of which are parallel, will be clearly demonstra- 
 ted ; and it will also be seen that these two bodies are not mere medullary bands, but 
 are two three-sided bundles occupying an angular groove between and in front of the two 
 ohvary bodies {fig. 269, C). 
 
 The decussation of the anterior pyramids demands attention, as one of the most impor- 
 tant points in the anatomy of the cerebro-spinal axis. 
 
 On examining the anterior median groove of the medulla oblongata (see^^*. 270, 276), 
 it will be found that, at a distance from the pons Varolii of about ten lines (Gall says an 
 inch and some lines), the anterior pyramids divide into three or four bundles, which al- 
 ternately interlace in a regular manner (below n), so as to form a plaited structure of from 
 two to four lines in length. Is this decussation only apparent 1 and if so, does the ap- 
 pearance result, as has been said, from the traction of parallel fibres in opposite direc- 
 tions 1 or do the pyramids commence by alternate bundles arising from each side of the 
 middle line, and does this alternate arrangement occasion the appearance of a decussa- 
 tion 1 or, lastly, do the right and left pyramids actually cross like the limbs of the letter X 1 
 
 On consulting the various authorities on this subject, it is found that the decussation 
 of the pyramids, first pointed out by Aretaeus, renoticed by Fabricius Hildanus, and de- 
 monstrated by Mistichellit and Pourfour Dupetit,t has been admitted by Santorini, Wins- 
 low, Lieutaud, Duverney, Scarpa, and Soemmering ; and that the opposite opinion has 
 been maintained by Morgagni, Haller, Vic d'Azyr, Sabatier, Boyer, Cuvier, Chaussier, 
 and Rolando.iJ As to Gall and Spurzheim, they do not seem to have had a decided 
 opinion upon this point ; for, after having appeared to admit the decussation in some 
 passages of their work, they say elsewhere that the small cords of the pyramids do not 
 form a true decussation, but merely intersect and pass over each other obliquely. 
 
 In order to settle the question of decussation, I submitted the medulla oblongata to 
 the action of a jet of water upon both its anterior and posterior surfaces ; and by then 
 examining it from behind forward, I was able to ascertain that the right and left p)Tam- 
 idal bundles do most evidently decussate (a, fig. 273) ; that this decussation is effect- 
 ed, not only from side to side, but also from before backward (i, fig. 274) ; that the left 
 pyramidal bundle (i) passes downward to the right side and backward (w), traverses the 
 gray matter of the cord, and becomes continuous with the right lateral column of the 
 cord, and vice versa ; and, lastly, that the anterior pyramids are not in the slightest de- 
 gree continuous with the anterior columns of the spinal cord. 
 
 The Olivary Bodies. — ^When the anterior pyramids are removed, it is seen that the 
 olivary bodies {d, figs. 273, 274) do not consist merely of the prominent masses which 
 project beyond and on the outer side of the anterior pyramids, but that they extend in- 
 ward to the median hne behind the pyramids, which are received in a slight concavity 
 formed by the anterior surfaces of the olivary bodies {fig. 269, C). This arrangement is 
 very evident, without any preparation, in anencephalous infants, or in such as are born 
 
 * If we employ a stream of water in the eiamination of a fresh medulla oblongata, it may easily be con- 
 ceived that the results will be much more conclusive than if we had thus examined one which had already 
 > been subjected to different modes of preparation that may have altered its structure. 
 
 t Trattato dell' Apoplessia, 1709. t Letters d'un Med6cin des Hdpitaux, 1710. 
 
 <t Of all who have denied the reality of the decussation, Rolando appears to me to have opposed the doctrine 
 vith the greatest force. He examined the subject with the greatest attention ; he made horizontal sections 
 
 ■ of the medulla oblongata, but he could never see anything more than the alternate origin of the fasciculi which 
 . eoastitute the anterior pyramids ; he could never find that the bundles of the right side passed over to the 
 
 left, and vice versd. In reply to the objection, that without admitting the decussation it is iinpossible to ac- 
 
 ■ count for the cross effects of injuries or diseases of the brain, he states that these are explained by the inti- 
 mate union between the optic thalanii and tubercula quadrigemina of the two sides, and between the two halves 
 of the pons Varolii and medulla oblongata. The error of Rolando evidently arose from his attaching such ei- 
 Husive importance to sections, as a means of determining the structure of the medulla ob\ongata. 
 
INTERNAL STRUCTURE OF THE MEDULLA OBLONGATA. 707 
 
 with very imperfectly-developed brains ; the situation of the atrophied pyramids is then 
 occupied by two tracts of gray matter, and the olivary bodies, more developed than usual, 
 reach as far as the median line. 
 
 When a jet of water is directed against the median line between the olivary bodies, 
 it encounters a white and very dense tissue, upon which it produces little effect.* 
 
 As soon as this tissue has been removed with the knife, the water insinuates itself 
 mto the substance of the olivary bodies, which, as we have seen, are open towards the 
 inner side ; each olivary body is then spread out, its anterior half is turned outward, and 
 assumes the appearance of a dense yellowish layer folded upon itself, like a leaf while 
 within its bud ; after some white lamellae are removed by the action of the water, the 
 posterior half is exposed, and displays a similar appearance to that of the anterior half 
 Rolando compares the arrangement of this yellow folded layer, or corpus dentatum of 
 the olivary body, to a flattened purse {borsa appiattita), the neck of which is open, some- 
 what constricted, and directed backward and towards the median line. 
 
 Gall and Spurzheim regarded the olivary bodies as ganglia, but these anatomists ap- 
 pear to me to have singularly misappUed the term ganglion, which they have given to 
 such dissimilar parts as the olivary bodies, the corpora striata, and the tuber annulare. 
 
 Lastly, by directing the stream of water against the median line, and by assisting its 
 action by gently drawing the parts asundei. the medulla oblongata becomes divided into 
 two perfectly similar halves, excepting opposite the decussation. A beautiful prepara- 
 tion may thus be made, exhibiting the separation of the two halves of the medualla ob- 
 longata and spinal cord, and leaving the decussation of the anterior pyramids. 
 
 It appears, then, on the one hand, that the anterior pyramids are not formed by the 
 anterior columns of the spinal cord ; and, on the other hand, that the posterior columns 
 of the cord become separated from each other behind when they have reached the me- 
 dulla oblongata. What, then, becomes of the white bundles of the cord in the medulla ob- 
 longata 1 
 
 Having arrived opposite the neck of the bulb, the white matter of the cord is divided 
 into two bundles : one anterior, which forms the anterior pyramid {b. Jig. 273), and may be 
 called the cerebral bundle, because it passes up (i') to the brain ; the other posterior, oi 
 the restiform body (c e), which may be called the peduncle of the cerebellum, because it is 
 exclusively intended (w) for that organ ; the former is composed of white bundles, which 
 emerge from the interior of the spinal cord, and the latter of the anterior columns, and 
 of the remaining white bundles of the cord. The olivary bodies {d) are situated between 
 these two sets of white fibres. 
 
 When, by means of the stream of water, the anterior pyramids and the restiform 
 bodies have been removed, it is seen that each half of the medulla oblongata is formed 
 principally of a very dense nucleus, consisting of a mixture of gray and white substances. 
 This nucleus, or fasciculus of re-enforcement of the medulla oblongata, which we shall call 
 the unnamed fasciculus (faisceau innomini) of the medulla, commences opposite the de- 
 cussation of the pyramids by a narrow extremity, increases in size as it proceeds up- 
 ward, passes above {I, fig. 274), i. e., deeper than the pons, and becomes continuous, as 
 we shall afterward see, with the corresponding optic thalamus. Each half of the medul- 
 la oblongata has its fasciculus of re-enforcement, of which the internal surface, viz., that 
 turned towards the middle line, corresponds to the fasciculus of the opposite side, but 
 is separated from it by the white fibres {p,fig. 274) already described (p. 706) as passing 
 horizontally from before backward, in the median line of the medulla. The posterior 
 surface of these fasciculi {p,fig. 271) constitutes the anterior wall of the fourth ventricle. 
 The corresponding peduncles of the cerebellum, or the restiform bodies, embrace them 
 on the outside, and form, as it were, grooves for them. 
 
 On examining thoroughly the internal or median surface of each re-enforcing fascicu- 
 lus of the bulb, it is found that there are two vertical bands upon that surface, one an- 
 terior, the other posterior ; and that the fibres which pass horizontally from before back- 
 ward in the median line of the medulla oblongata are situated between the bands of the 
 right and left sides. 
 
 Each fasciculus of re-enforcement is divided above into two parts, one of which forms 
 the centre of the corresponding restiform body, while the other becomes continuous with 
 the optic thalamus above the pons Varolii. 
 
 I have not alluded to the olivary fasciculi admitted by some anatomists, for the white 
 bundles so called do not even come from the olivary body, but form the continuation of 
 the lateral columns of the spinal cord, which embrace the olivary bodies on the outer 
 side, without being re-enforced by any bundles derived directly from them.t 
 
 * I have frequently been led to regard the white medullary substance which is situated between the olivary 
 bodies, and passes into each of them, as a transverse commissure, which might be called the commissure ot 
 the olivary bodies. 
 
 t [The bundles, named faisccaux innommin^s in the text (fasciculi teretes of some other authors), which M. 
 Cruveilhier describes as taking their rise at the lower end of the medulla oblongata, are more generally con- 
 sideied to be prolonged from the lateral columns of the cord ; and on comparing the statements of recent in- 
 quirers concerning the anatomy of the medulla oblongata, the following appears to be the arrangement which 
 the columns of the cord undergo in passing through it, viz., the posterior columns (including the postonor me 
 diau fasciculi, which correspond with the posterior pyramids) separate laterally f'om one another (f,figs.Zi3, 
 
708 NEUROLOGY. 
 
 Development of the Spinal Cord. 
 
 As soon as the spinal cord has passed through its original condition of an almost 
 transparent pulp, it assumes the appearance of a lamina, the edges of which are rolled 
 back upon themselves so as to enclose a canal, continuous with the cavity of the fourth 
 ventricle, which might be regarded as the expanded extremity of the canal. This canal 
 is narrowed along the middle by the reflection of the pia mater into it : it is thus con- 
 verted into two canals, the walls of which are at first thin, but afterward increase in 
 thickness, gradually encroach upon the caliber of the canals, which finally disappear be- 
 tween the sixth and seventh month. At this period a thin, white, outer layer covers the 
 whole medulla : the posterior median columns are very large, and of a white colour, 
 while the antero-lateral columns are still semi-transparent, the gray matter is soft and 
 diffluent, like a pulp ; and, by the slightest insufllation, a canal may be formed along the 
 centre of each half of the cord. 
 
 The spinal cord occupies the whole length of the vertebral canal until the third month ; 
 but after this time, its lower extremity becomes relatively higher up to the period of 
 birth, when it corresponds to the second lumbar vertebra. 
 
 The spinal cord is larger, in proportion to the brain, during the early periods of foetal 
 hfe, than afterward. The more rapid development of the brain, at later periods, gives 
 that organ the advantage. 
 
 From studying the development of the spinal cord, Tiedemann infers that the white 
 substance exists before the gray, and therefore that the latter cannot be the nutritious 
 organ or matrix of the white substance, as Gall had affirmed. 
 
 It is quite certain that the white parietes of the medullary canal are developed pre- 
 viously to the gray matter. 
 
 Development of the Medulla Oblongata. 
 
 During the first three months of intra-uterine life, the upper limit of the medulla ob- 
 longata is not defined, because there is no pons Varolii. The foetal brain, therefore, in 
 this condition, resembles the brains of birds, reptiles, and fishes. The transverse fibres 
 of the pons make their appearance during the fourth month, and the upper limit of the 
 medulla oblongata is then established. 
 
 The two halves of the medulla oblongata are perfectly distinct, and each half is divi- 
 ded into three columns : one for the brain properly so called, viz., the anterior pyramidal 
 bundle ; another for the tubercula quadrigemina, which may be called, with Tiedemann, 
 the olivary bundle, remembering, at the same time, that this term has a very diiferent 
 meaning from what was attached to it by Gall ; and a third or cerebellar bundle, which 
 is the restiform body. 
 
 The anterior pyramidal bodies are at first flattened like those of mammalia, but during 
 the latter months they acquire their characteristic size and prominence. In the medulla 
 oblongata of a foetus, from the seventh to the ninth month, the anterior pyramids are of 
 a reddish-gray colour, while the anterior columns of the spinal cord are as white as they 
 appear afterward. Those pyramids, therefore, are not the continuation of the anterior 
 columns of the cord. 
 
 The decussation of the pyramids is perfectly distinct after the fourth week of foetal 
 existence.* 
 
 The olivary bundles of Tiedemann, which are situated to the outer side of the anterior 
 pyramids, and, like them, traverse the pons, gain the sides of the tubercula quadrigemina, 
 beneath which they form an arch, which constitutes the upper wall of the aqueduct of 
 Sylvius. The olivary bodies, which are wanting in birds, reptiles, and fishes, do not ap- 
 pear until the end of the sixth or the commencement of the seventh month of foetal life. 
 
 The cerebellar bundles, or restiform bodies, are perfectly distinct from the preceding. 
 The small manmiillated bundles which bound the sides of the posterior longitudinal 
 groove can also be distinguished in the foetus. 
 
 Comparative .Anatomy of the Spinal Cord. 
 Mammalia. — The spinal cord of mammalia precisely resembles that of the human sub- 
 
 274), and enter the cerebellum, forming the principal part of its inferior peduncle (n). The fibres of the lat- 
 eral columns are disposed of in three ways: 1. A part of thfem cross the median plane to the opposite side (m. 
 Jig. 273), and form the chief part of the pyramidal body (A) of that side. 2. Another set join the inferior pe- 
 duncle of the cerebellum. 3. The remainin<f fibres are continued along the floor of the fourth ventricle l.p,fig 
 271), as the fasciculi innominati or fasciculi teretes. The anterior columns (a, fig. 273) of the cord, on enter- 
 ing the medulla oblongata, are thrown aside by the decussating fibres coming from the lateral columns, and 
 then one portion of each anterior column forms the outer part of the coiTesponding pyramid (i) ; another por 
 tion {c,fig. 274) passes partly behind and partly on the outer side of the olivary body, and is then chiefly con 
 tinued into the fillet (A) ; the remaining part passes into the cerebellum, joining its inferior peduncle (n) 
 The connexion of the cerebellum with the anterior columns of the cord was pointed out by Mr. Solly. — (Phil. 
 Trans., 1836, p. 567.) Arnold describes the posterior pyramids (fasciculi gracilea) as passing into the crura 
 cerebri. For farther details on the anatomy of the medulla oblongata, the reader is referred to Arnold's 
 Bemerkungen itber den Bau des Hirns und Ruckenmarks, Zurich, 1838 ; also his Icones Anatomica, fasc. i. , 
 and to a paper by Dr. J. Reid in the Edtn. Med. and Surg. Journ. for January, 1841.] 
 
 * [The fourth or fifth month, accordino- to Tiedemann ; though in one part of his work " week" has been, 
 by an error, printed for "month."] 
 
COMPARATIVE ANATOMY OF THE MEDULLA OBLONGATA. 709 
 
 ject : its length, its size, its enlargements, are exactly proportioned to the size and ac- 
 tivity of the muscles, and to the sensibility of the organs with which it is connected by 
 means of the nerves. 
 
 Birds. — The spinal cord in birds is proportionally both longer and larger than in other 
 animals ; and this has reference to the enormous muscular effort required in flying. It 
 presents two great enlargements ; one of these corresponds to the wings, and the other, 
 which is larger, and contains a ventricle, corresponds to the lower extremities ; this 
 ventricle was known to Steno, who described it under the name of the rhomboidal sinus. 
 
 According to Nicolai {Dissertatio de Medulla Spinali Avium, Halle, 1811) and Tiede- 
 mann, the spinal cord of birds contains a central canal, which is lined by a thin layer of 
 gray matter, not only in the embryo, but also in the adult. 
 
 Reptiles.- — In all reptiles the spinal cord contains a canal, which is lined, according to 
 Tiedemann, by a thin layer of gray substance. In the batrachian reptiles (the toad, frog, 
 &c.), the spinal cord occupies only the anterior or upper part of the vertebral canal. M. 
 Desmoulins says (t. i., p. 187) that the gray matter in these species surrounds the white 
 substance. This opinion appears to me to be erroneous. 
 
 In ophidian reptiles (serpents), the spinal cord occupies the whole length of the verte- 
 bral canal ; there is no gray matter,* but its place is occupied by a fluid, so that each 
 half of the medulla contains a canal. 
 
 In the saurians (crocodiles, lizards), the spinal cord is slender, of almost uniform size 
 throughout, and occupies the whole length of the vertebral canal. 
 
 The spinal cord of the chelonian (tortoises, &c.) is the most remarkable of all, as re- 
 gards its shape, and is peculiarly illustrative of the law which regulates the dimensions 
 of this organ. There are three fusiform enlargements separated from each other by two 
 very narrow portions ; the middle enlargement corresponds to the upper extremities, and 
 the inferior one to the lower extremities ; the first constriction corresponds to the neck, 
 the second to the thorax. 
 
 Fishes. — In all f^hcs the spinal cord occupies the entire length of the vertebral canal. 
 It is of uniform size in its anterior five sixths, but diminishes like a cone in the posterior 
 sixth. There is no gray matter,t so that the cord is hollow. According to Arsaky 
 (^Dissert, de Piscium Cerebro) and Tiedemann, the medullary canal is lined by a thin layer 
 of gray matter. 
 
 The lophius piscatorius and the male tetrodon present remarkable anatomical peculi- 
 arities ; in the lophius, the spinal cord is diminished in size opposite the third cervical 
 vertebra ; all at once it becomes extremely slender, and then terminates in a point op- 
 posite the eighth cervical vertebra. Twenty-six pairs of nerves arise from the enlarged 
 portion, and only five or six" pairs from the slender portion. In the tetrodon there is no 
 spinal cord, properly so called, or, rather, this part of the cerebro-spinal axis is reduced 
 to a medulla oblongata, from which arise thirty-two pairs of nerves. 
 
 From these facts, it follows that the length and size of the spinal cord bear an exact 
 proportion to the muscular power and sensibility of the parts supplied by it ; and farther, 
 that the gray matter of the cord is not nearly so important as the white substance, since 
 it is absent in a great number of species. J 
 
 Comparative Anatomy of the Medulla Oblongata. 
 
 In the mammalia the medulla oblongata is constructed upon the same plan as in the 
 human subject, but the anterior pyramids are much smaller, and the olivary bodies ap- 
 pear to be completely effaced. The tubercula cinerea of Rolando exist only in man ; 
 in whom alone do we find those white streaks of medullary substance upon the anterior 
 wall of the fourth ventricle, which are regarded as forming, at least in part, the origins 
 of the auditory nerves. 
 
 The medulla oblongata of birds and reptiles presents no striking peculiarities. In the 
 different species its size is always in proportion to that of the fifth, and especially the 
 eighth pair of nerves, which take their origin from this part. 
 
 In fishes a peculiar pair of lobes correspond to the medulla oblongata ; these lobes were 
 for a long time erroneously supposed to be the lateral lobes of the cerebellum, and have 
 thus led to much obscurity concerning the anatomy of the encephalon in these animals. 
 Desmoulins calls them the lobes of the fourth ventricle ; we shall call them the lobes of 
 the eighth pair of nerves. In the ray and sturgeon this lobe is so highly developed, that 
 it forms half of the encephalic mass. In the carp, besides the lateral lobes which are 
 traversed by some white fibres, there is also a median lobe. Moreover, as a general 
 rule, whenever the spinal cord has to furnish any nerves, there is an enlargement or a 
 lobe. In the torpedo, in which the eighth pair of nerves are of enom^ous size, and sup- 
 ply the electrical organ, these lateral lobes are in an extraordinary degree developed. In 
 the trigla there are certain small lobes behind the cerebellum, which correspond to the pe- 
 culiar digitiform prolongations serving as organs of progression in the animals in question. 
 
 * [The spinal cord of serpents forms no exception to the general rule ; gray matter has been recognised in 
 it, as in the cord of other vertebrated animals. The same is true of fishes.— (See Leuret, Anatoime Com- 
 parie du Systime Nerveux, ^c, Paris, 1839.)] t See note, siipru. t See note, supra. 
 
71© NEUROLOGY. . 
 
 The olivary bodies are most highly developed in the human subject ; they exist also, 
 but are very small, in some mammalia ; they disappear in birds, reptiles, and fishes. I 
 consider the olivary bodies as lobes in a rudimentary state. 
 
 THE ISTHMUS OF THE ENCEPHALON. 
 
 General Description and Division. — The Pons Varolii and Middle Peduncles of the Cere- 
 bellum — the Peduncles of the Cerebrum — the Superior Peduncles of the Cerebellum and the 
 Valve of Vieussens — the Corpora Quadrigemina. — Internal Structure of the Isthmus, viz., 
 of its, Inferior, Middle, and Superior Strata. — Sections. — Development. — Comparative 
 Anatomy. 
 
 I SHALL, with Ridley, apply the term isthmus of the encephalon to that narrowed 'and 
 constricted portion of the encephalic mass which is situated between the cerebrum, cere- 
 bellum, and medulla oblongata, which corresponds to the free margin of the tentorium 
 cerebelli, and comprises the pons Varolii and middle peduncles of the cerebellum, the 
 peduncles of the cerebrum, the tubercula quadrigemina, the superior peduncles of the 
 cerebellum, and the valve of Vieussens. 
 
 The isthmus of the encephalon is the common point of union between the three great 
 divisions of the cerebro-spinal axis, viz., the medulla spinalis, the cerebrum, and the 
 cerebellum. It contains within it the media by which they all communicate, or, as it 
 may be said, the elements of each reduced to their most simple expression. 
 
 It is of a cuboid form, and therefore presents six surfaces for our consideration : 
 
 An inferior surface (fig. 276), on which we observe the pons Varolii, or tuber annulare 
 (d), the middle peduncles of the cerebellum (m), and the peduncles of the cerebrum (//). 
 
 A superior surface {fig. 271), which is covered by the superior vermiform process of 
 the cerebellum, by the velum interpositum, and by the posterior border of the corpus cal- 
 losum. In order to expose this surface, supposing the brain to be with its base upward, 
 the cerebellum must be turned forward, and the pia mater should be separated, taking 
 care to lift up with it the pineal gland. Proceeding from before backward, the following 
 parts come into view: the tubercula quadrigemina (fg), resting upon them the pined 
 gland (c), the superior peduncles of the cerebellum (shown in cut at r ; also r, fig. 272), 
 and the valve of Vieussens il,fig. 271). 
 
 The lateral surfaces {fig. 272) are each divided into two distinct parts or stages, by a 
 furrow which runs from before backward (the lateral furrow of the isthmus) ; the inferior 
 stage consists of the pons Varolii (a) and the middle peduncles of the cerebellum (m), 
 while the superior is narrower, lies closer to the median line than the preceding, and 
 presents a triangular fasciculus (A), having its base directed downward, and its apex turn- 
 ed upward, so as to reach the corresponding inferior quadrigeminous tubercle or testis {g). 
 
 The anterior surface of the isthmus is continuous with the optic thalami {s, fig. 272). 
 
 The posterior surface is much narrower than the anterior, and is continuous with the 
 base of the medulla oblongata. 
 
 We shall examine the several parts of the isthmus in the following order : the pons 
 Varolii and middle peduncles of the cerebellum, the peduncles of the cerebrum, the superior 
 peduncles of the cerebellum, the valve of Vieussens, and the tubercula quadrigemina. The in- 
 ferior peduncles of the cerebellum have been already described with the rest of the medulla 
 oblongata, under the name of the restiform bodies. 
 
 The Pons Varolii and Middle Peduncles of the Cerebellum. 
 
 The pons Varolii, or tuber annulare,* is that white cuboid eminence {d, fig. 276) situa- 
 ted between the cerebrum and cerebellum, upon the base of the encephalon, and form- 
 ing, as it were, its centre (mesocephale, Chauss. ; nodus encephali, Scemm.). From this 
 centre the several parts proceed as follows : backward, the medulla oblongata (e) ; for- 
 ward, two thick white bundles, which pass into the brain, and form the anterior or cere- 
 bral peduncles {ff); laterally, two thick bundles, which enter the cerebeUum, and are 
 named the posterior peduncles, or middle cerebellar peduncles {m). 
 
 The pons Varolii, the cerebral and cerebellar peduncles, and the medulla oblongata 
 proper, are together called the medulla oblongata by some authors ; several of the older 
 anatomists, in fact, compared the pons to the body of an animal, of which the anterior 
 peduncles represented the arms ; the posterior, the legs ; and the medulla oblongata 
 proper, the tail ; and hence the terms still in use of the arms, legs, and tail of the so- 
 called medulla oblongata. It was Varolius who compared this part to a bridge, under 
 which the several branches of a stream, supposed to be represented by the peduncles and 
 the medulla oblongata, joined each other ; hence the terms pmis Varolii and pons cerebelli. 
 
 The pons is free below, but is blended above with the upper portion of the isthmus ; 
 it is bounded in front by the peduncles of the cerebrum, and behind by the meduUa ob- 
 longata ; and it is continuous, laterally, with the middle peduncles of the cerebellum {m), 
 
 * The term tuber annulare is derived from the fact that this part of the enceohalon seems to embrace tb« 
 several prolongations of the medulla oblongata like a ring. 
 
THE PEDUNCLES OP THE CEREBRUM, ETC. 711 
 
 forming with them but one system of fibres ; its lateral boundaries are, therefore, alto- 
 gether artificial. 
 
 The size of the pons, which is very considerable in the human subject, is always in 
 relation with the development of the lateral lobes of the cerebellum ; comparative anat- 
 omy, embryology, and the study of malformations completely establish this fact.* 
 
 Its inferior surface is covered by the pia mater, which can be easily stripped off; it 
 rests upon the anterior part of the basilar groove, and slopes backward and downward 
 like the incl»ed plane of that groove. 
 
 It presents along the median line a slight furrow, which is broader in front than be- 
 nind, and corresponds to the basilar artery : this groove appears as if it were caused by 
 the presence of the artery ; nevertheless, I must say, that not unfrequently the basilar 
 artery is found to deviate to one side or the other, or to be more or less tortuous, and 
 yet that the median groove is as distinctly marked as usual. 
 
 I beUeve there is good ground for entertaining the opinion that this groove results from 
 the prominence of the anterior pyramids, which raise up the surface of the pons on each 
 side of the median line. 
 
 The inferior surface of the pons presents certain transverse bundles or fibres, which 
 appear to cross each other at very acute angles, and which, according to Rolando, may 
 be divided into three sets : superior bundles, which turn upward, to constitute the upper 
 part of the middle peduncles of the cerebellum ; inferior bundles, which pass transversely 
 outward ; and middle bundles, which are directed obliquely downward and outward, pass 
 in front of the inferior bundles, and then form the anterior border of the cerebellar pedun- 
 cles. The origin of the fifth pair of nerves is between the superior and middle sets of 
 fibres. Not uafrequently the middle bundles are not to be seen. 
 
 It follows, therefore, that the middle peduncles of the cerebellum are merely the trans- 
 verse fibres of the pons condensed and twisted upon themselves. The pons and these 
 peduncles of the cerebellum constitute one and the same system of fibres. We might 
 therefore, with Gall, designate the pons and the middle peduncles of the cerebellum as 
 the commissure of the cerebellum, or corpus callosum of the cerebellum. 
 
 The Peduncles of the Cerebrum. 
 
 The peduncles of the cerebrum (//, fig. 276), sometimes regarded as prolongations of 
 the cerebrum to the medulla oblongata ( processus cerebri ad medullam oblongatam, ad pon- 
 tem Varolii), sometimes as the arms, legs, or thighs of the cerebrum {brachia, crura, femo- 
 ra, cerebri), and by others as prolongations of the medulla towards the cerebrum (proces- 
 sus medullm oblongata ad cerebrum), are two thick, white, fasciculated columns, which 
 arise from the anterior angles of the pons Varolii, and enter the substance of the cere- 
 brum, after a course of about six lines. 
 
 They are cylindrical, and in contact with each other as they emerge from the pons ; 
 and they gradually increase in size, and become flattened as they advance forward, up- 
 ward, and outward. The optic tracts (s 2, fig. 272) circumscribe and bound them in front. 
 
 Their size corresponds to that of the cerebral hemispheres. They are of equal di- 
 mensions in a well-formed brain, but they are liable to become atrophied with their cor- 
 responding hemisphere, as I have had frequent occasion to observe. 
 
 Each of them is free below, and on its outer and inner side, but is blended above with 
 the upper portion (A ifg, fig. 272) of the isthmus of the encephalon. 
 
 Their white fasciculi are slightly divergent, and are often intersected at right angles 
 by certain white tracts, some of which emerge from the testes and the valve of Vieus- 
 sens, while others proceed from the internal surfaces of the peduncles themselves. This 
 arrangement Gall and Spurzheim have named the transverse interlacement of the great 
 fibrous bundles {see fig. 272). Owing to the oblique and diverging direction of the cere- 
 bral peduncles, there is left between them a triangular inter-peduncular space (between r 
 and t, fig. 276), which is occupied in front by the corpora manmiillaria or albicantia (z) 
 and the tuber cinereum (v), and in which is observed behind two white triangular bun- 
 dles, separated from the peduncles by a blackish line. We shall see that these inter-pe- 
 duncular bundles are merely the under surface of the bundles of re-enforcement of the 
 medulla oblongata, or the " faisceaux innomines" {I, fig. 274). 
 
 The Superior Peduncles of the Cerebellum and the Valve of Vieussens. 
 
 The superior peduncles of the cerebellum (r, figs. 271, 272, 280) are more commonly known 
 as the processus cerebelli ad testes, a name given to them by Pourfour Dupetit. I should 
 observe, however, that this name sanctions an anatomical error ; for the superior pedun- 
 cles of the cerebellum do not go to the testes at all, but pass under them, and are cover- 
 ed by the corresponding lateral triangular bundle of the istlmius ; they should rather be 
 called processus cerebelli ad cerebrum {Drelincourt.) 
 
 The inferior peduncles of the cerebellum consist of two lamellae, which arise from the 
 
 * Animals which have no lateral lobe of the cerebellum have no pons Varolii, and this part is small in such 
 as have very small lateral cerebellar lobes. In a young- girl ten years of age, who had no cerebellum, I fuund 
 that the pons was also wanting. 
 
fj^tf NEUROLOGY. 
 
 interior of the cerebellum, one on each side of the median line, pass upward and forward 
 parallel to each other, and appear to be continuous with the testes. 
 
 Their upfer convex surface is covered by the cerebellum {see fig. 280), and is separated 
 from it by a double layer of the pia mater. Their inferior surface is free, and assists in 
 forming the upper wall of the aqueduct of Sylvius. Their external borders are each sep- 
 arated from the pons by a furrow, which we have already described under the name of 
 lateral furrow of the isthmus. Their internal borders are connected together by means of 
 the valve of Vieussens, which is distinguished by its colour from the peduncles. 
 
 Their inferior extremities pass deeply into the central white substance of the cerebellum. 
 
 The valve of Vieussens {valvula magna cerebri, I, fig. 271 ; v, fig. 280 ; g to w, fig. 282) 
 is a thin, semi-transparent lamina, which occupies the interval between the two superior 
 peduncles of the cerebellum ; it is the velum medullar e or velum inter jectum of Haller. 
 
 Its posterior surface is concave, and is in relation above with the superior vermiform 
 process ; in its lower portion it adheres to the transversely-notched imperfect lamella 
 (linguetta laminosa, Malacarne), in which the superior vermis ends. 
 
 The median line of this posterior surface is marked by a line {fig. 271), which Rolan- 
 do considers as the trace of the line of junction between the two laminae, of which, ac- 
 cording to him, the valve consists. 
 
 The anterior surface is convex, and forms the posterior w^ of the aqueduct of Sylvius 
 (leading from v to /, fig. 282). 
 
 The borders of the valve ^xe not only in juxtaposition with the corresponding borders 
 of the superior peduncles of the cerebellum, but appear to be continuous with them. 
 
 The superior extremity is narrow, and presents a transverse band, which may be re- 
 garded as the commissure of the superior peduncles of the cerebellum Euid of the fourth 
 pair of nerves. 
 
 The inferior extremity is broad, very thin, and continuous with the central portion ol 
 the median lobe of the cerebellum (w). 
 
 The Tuber cula Quadrigemina. 
 
 Dissection. — Place the brain with its base upward, turn the cerebellum forward, and 
 remove the pia mater. 
 
 The term tubercula quadrigemina or bigemina (corpora bigemina, Soemmering, optic lobes 
 of the lower animals) is applied to four tubercles {fgfg,figs. 271, 272) situated regu- 
 larly upon the upper surface of the isthmus, two on each side of the median line. They 
 form two pairs : the anterior or superior (/) are the larger, and are called the nates (emi- 
 nentia. natiformes) ; the posterior or inferior {g) are the smaller, and are called the testes 
 {eminentia testiformes). 
 
 These tubercles are placed between the cerebrum and cerebellum, and are situated 
 above the peduncles of the cerebrum, and, consequently, upon a plane anterior to that of 
 the pons, and cannot consistently be named the tubercles of the mesocephalon, as was done 
 by Chaussier. The anterior part of the aqueduct of Sylvius passes beneath them (.fg,fig- 
 282), and establishes a communication between the third (l) and fourth (v) ventricles. 
 
 They are comparatively small, indeed merely rudimentary in the human subject, for 
 their development in the animal series is inversely as that of the cerebrum and cerebel- 
 lum. The space which they occupy is a parallelogram of ten lines by eight. 
 
 The anterior tubercles are always larger than the posterior ;* they are of a gray col- 
 our, oblong, ellipsoid, and diverging ; their longest diameter is directed obliquely forward 
 and outward. The posterior tubercles are smaller, and more detached ; they are almost 
 hemispherical, and of a white colour ; but not so white as the fasciculated medullary sub- 
 stance. 
 
 A furrow, curved like a parabola opening forward, separates the anterior from the pos- 
 terior tubercles. The antero-posterior furrow along the median line separates the tu- 
 bercles of the right from those of the left side. From this furrow, a small, grayish, and 
 tolerably dense cord proceeds backward, and descends perpendicularly upon the valve of 
 Vieussens, or, rather, upon the transverse commissure by which it is surmounted, and 
 then divides into two or three branches. This cord might be named the pillar of the 
 valve of Vieussens {columella frenulum). 
 
 The lateral triangular bundle {h,figs. 271, 272) of the isthmus terminates in the poste- 
 rior tubercle. This fasciculus, which was pointed out by Reil (" schleife," lemniscus, 
 fillet), Tiedemann, and Rolando, who described it as arising from the olivary bodies, pre- 
 sents an anterior border, which is directed obliquely forward and outward, proceeds along 
 the anterior tubercle, and terminates in a small body called the corpus genicidatum inter- 
 num {i, figs. 271, 272). Its posterior border inclines downward, backward, and outward, 
 and forms a slight prominence above the superior peduncle of the cerebellum, which is 
 covered by it. Its base corresponds to the lateral groove of the isthmus, which separ- 
 ates it from the pons and the peduncle of the cerebrum. Its apex extends to the corre- 
 
 * The relative size of the tuberculii quadrigemina varies somewhat in different animals. The anterior tuber 
 cles are much larger than the posterior in ruminants, solipeds, and rodentia ; they are smaller than the j>os- 
 terior in camivora — in the dog, for example. 
 
INTERNAL 8TRUCTUEK OP THE ISTHMUS OP THE ENCEPHALON. 713 
 
 sponding posterior tubercle or testis. The anterior tubercles or nates are continuous 
 with the optic thalami (a, fig. 271), being separated from them by a slight depression. 
 Some white fibres proceed from the anterior extremity of these tubercles, and, as we 
 shall afterward see, form a thin layer above the corresponding corpus geniculatum ex- 
 ternum (;'), and assist in the formation of the optic nerves. These white bands are gen- 
 erally proportioned to the size of the nates.* 
 
 The Internal Structure of the Isthmus of the Encephalon. 
 
 Dissection. — By antero-posterior and transverse sections of the isthmus. The parts 
 to be examined by laceration, by submitting them to the action of a stream of water, and 
 also after they have been hardened in alcohol, or by being boiled in oil, or a solution of salt. 
 
 The internal structure of the isthmus presents three very distinct strata placed one 
 upon the other : an inferior, formed by the pons, the middle peduncles of the cerebellum, 
 and the fasciculated portion of the peduncles of the cerebrum ; a middle stratum, form- 
 ed by the prolongation of the bundles of re-enforcement of the medulla oblongata ; and a 
 superior stratum, which consists of the triangular lateral bundles of the isthmus, the su- 
 perior peduncles of the cerebellum, the valve of Vieussens, and the tubercula quadri- 
 gemina. 
 
 iTiternal Structure of the Pons and the Peduncles of the Cerebellum. 
 
 It has been stated that the lower surface of the pons presents some white transverse 
 fibres (see left side, fig. 273), which twist g^ ^^^ 
 
 upon each other to form the middle pedun- '^ ^^/ 
 
 cles of the cerebellum. On making a very 
 superficial incision into the pons, we find, 
 beneath the external layer of white matter, 
 which is very thin behind, and a little thick- 
 er in front, a grayish-yellow substance, 
 which is traversed by the transverse fibres 
 of the pons, so that the part (m, fig. 274) 
 has a striated appearance. 
 
 If the handle of the scalpel be passed be- 
 neath the anterior border of the pons, so as 
 to remove all that part which projects be- 
 yond the level of the peduncles of the cere- 
 brum, it will be seen that the pons is trav- 
 ersed longitudinally by certain white bun- 
 dles of fibres {b', figs. 273, 274) ; and if, moreover, the handle of the scalpel be insinuated 
 beneath the posterior border of the pons, and all that part be removed which projects be- 
 yond the pyramidal bodies of the medulla oblongata, these white longitudinal bundles 
 which traverse the pons are found to be the prolongation of the pyramids (i), and are 
 themselves continuous with the peduncles of the cerebrum {n,fig. 282). By thus separ- 
 ating the pons into very thin horizontal layers, it will be found that the longitudinal {b') 
 and transverse (m) fibres form several alternate layers, above which we arrive at the 
 middle stratum of the isthmus. 
 
 The peduncles of the cerebrum are continuous with the longitudinal fibres of the pons, 
 and the middle cerebellar peduncles with the transverse fibres of the same part ; the 
 gray matter of the pons extends into the substance of%he latter, and gives them a stria- 
 ted appearance. At the boundary between the pons and the middle peduncles of the 
 cerebellum there is on each side a very considerable longitudinal bundle, which forms 
 the origin of the fifth nerve, and which, therefore, does not belong to the anterior pyram- 
 idal bodies.! m 
 
 The absolute continuity of the anterior pyramids with the peduncles of the cerebrum, 
 through the pons, may be regarded as a type of the structure of the nervous centre. The 
 two sets of fibres are intermixed in the pons, so as to intersect each other at right an- 
 gles, but they maintain their individuality, t 
 
 The pons presents neither a raphe nor a septum in the median line : the fibres of the 
 right half are continuous with those of the left. The white fasciculated fibres {b') of the 
 
 * They are very large in the sheep ; it appears that it was chiefly from the anatomy of the brain in this an- 
 imal that Gall founded his opinions as to the optic nerves, which he regards as arising from the tubercula 
 quadrigemina. This opinion is very doubtful as far as concerns the human subject. 
 
 t The most anterior and the most posterior transverse fibres of the pons have a very peculiar arrangement 
 the anterior are inflected {o,fig. 282) between the peduncles of the cerebrum, and completely occupy the in- 
 terval between them ; so that each of these peduncles is embraced by a distinct ring, formed by the fibres of 
 the pons ; and, again, the most posterior fibres of the pons dip between the anterior pyramids, each of which 
 is also embraced by a distinct ring. 
 
 t The continuity of the pyramids with the peduncles of the cerebrum, through the inferior portion of the 
 pons, was accurately described and figured by Varolius (Dc Nervis Opticis nonnulksque aliis, 1573), by Vieus- 
 sens {NeuTographia Universalis, tab. 16), by Morgagni {Adversaria Anatomica, v.), and by Vicq d'Azyr. Vieus 
 lens showed this continuity by lacerating the pons. Vicq d'Azyr showed it by successively removing the thin 
 layers of the pons by means of a cutting instrument. The plates given by Gall surpass those of his predeces- 
 sors in execution, but not in a scieatific point of view. 
 
 4X 
 
'714 NEUROLOGY. 
 
 peduncles of the cerebrum, which are continuous with the anterior pyramids (A), form 
 part of the inferior stratum of the isthmus ; these fasciculated fibres are parallel and per- 
 fectly white, without any intermixture of gray matter. 
 
 Internal Structure of the Middle Stratum of the Isthmus. 
 When the pons, or, in other words, the successive layers of the inferior portion or 
 etratmn of the isthmus, have been removed, the middle stratum is exposed. This may 
 Fiff. 274. be very easily displayed in a brain that has been 
 
 well hardened in alcohol. It is then seen that this 
 middle stratum is formed by a prolongation of the 
 fasciculi of re-enforcement \faisceauxinnominis) of 
 the medulla oblongata, which becomes enlarged in 
 passing above the pons, and still more so opposite 
 the peduncles of the cerebrum, above which we 
 shall trace them presently. This prolongation {I, 
 fig. 274) then passes through the pons at right an- 
 gles. It was doubtless to illustrate this arrange- 
 ment that Varolius described the medulla, when 
 viewed from below, as passing beneath the pons 
 like the water of a canal under a bridge. This re-enforcing bundle, pointed out by Ro- 
 lando {Recherches sur la Moelle Alongee, 1822) under the appellation of the middle fasci- 
 culus, has been correctly represented by Mr. Herbert Mayo. 
 
 Those portions (c, fig. 269, A) of the bundles of re-enforcement which correspond to 
 the peduncles of the cerebrum are separated from the superficial part of the peduncles 
 themselves (a) by a layer of black or blackish matter (5) : opposite the peduncles, these 
 two bundles are intimately united,* but they soon diverge to enter the optic thalami. 
 Are they simply in juxtaposition, or do they interlace at the point in which they appear 
 to be blended 1 I am inclined to believe that they do interlace ; but I have not yet been 
 able to demonstrate this clearly, because they do not consist of very distinct bundles. 
 
 The Internal Structure of the Upper Stratum of the Isthmus. 
 
 The superior peduncles of the cerebellum are fasciculated : their lower extremities {r,jig. 
 274) assist in forming the central nucleus of the cerebellum ; their upper extremities (r') 
 expand into a great number of fibres, some of which terminate upon the anterior wall 
 of the fourth ventricle, on each side of the median line, while others form a loop below 
 the tubercula quadrigemina. 
 
 Structure of the Tubercula Quadrigemina. — Reil, who first examined the structure of 
 the tubercula quadrigemina, considers them as consisting of four rounded masses of 
 gray matter, placed upon the radiated fibres of a white bundle, which spreads out beneath 
 them. This white bundle (forming part of the bundle h, fig. 274), which he calls the ^Z- 
 let or loop, is derived (c), according to him, partly from the anterior pyramidal, and part- 
 ly from the olivary body (^d). It appears to me to be nothing more than the above-men- 
 tioned loop formed by the superior peduncles of the cerebellum, below the tubercula 
 quadrigemina. 
 
 The tubercula quadrigemina themselves seem to me to be rather of a laminated than 
 of a fasciculated structure. Mayo represents them as having a fasciculated texture. 
 
 The triangular lateral fasciculus of the isthmus (A, fig. 272) passes in one direction be 
 tween the upper and middle strata of the isthmus, and in another it may be traced (form- 
 ing the other part of the bundle h, fig. 274) downward as far a^s the olivary body. The 
 anterior fibres extend from the testis {g) to the corpus geniculatum internum (»), pass 
 beneath that body, and penetrate into the interior of the optic thalamus. This triangu- 
 lar fasciculus forms a layer upon the superior peduncle of the cerebellum, from which it 
 is perfectly distinct. 
 
 Sections of the Isthmus of the EncephaJon. 
 
 A vertical section made from before backward through the median line of the istnmus 
 will give an excellent view of its three portions or strata : the section should include the 
 medulla oblongata (see fig. 274). Upon it are seen the white and gray striated mass 
 (m b' m) which constitutes the pons, the re-enforcing fasciculus (/) of the medulla oblon- 
 gata becoming much thicker opposite the peduncles of the cerebrum than in the pons. 
 
 Transverse vertical sections will display the arrangement of the pyramidal bodies and 
 the re-enforcing fasciculi as they pass from the medulla oblongata into the isthmus. In 
 these sections a thick bundle belonging to the fifth nerve is always seen. 
 
 Sections of the tubercula quadrigemina show that they are neither distinct from each 
 other, nor from the external and internal corpora geniculata, nor from the re-enforcing 
 fasciculi of the medulla oblongata ; but that these latter fasciculi and the tubercula qua- 
 drigemina form a single system, surmounted by masses of nervous matter, which are 
 the tubercles themselves. 
 
 * IThey here constitute the so-called integumentum (c,fig. 269, A) : the black snbstance is called the locut 
 tiger (6), and the suj^rficial part of the peduncle is named the crust or basis (o).] 
 
THE CEREBELLUM. 715 
 
 Development of the Isthmus Encephah. 
 
 The development of the pons and of the peduncles of the cerebellum is in relation 
 with that of the cerebellum ; and the development of the cerebral peduncles with that of 
 the cerebrum. 
 
 In the embryo of two months, the tubercula quadrigemina consist merely of two lam- 
 inae, which curve upward and outward, and become united at the end of the third month. 
 
 At this period the tubercula quadrigemina of the human subject are in the same con- 
 dition as those of the lower animals. They are as yet, indeed, only two in number, one 
 on each side of the middle line ; and they are hollow, as in birds. At first they are com- 
 pletely exposed, but are gradually covered by the hemispheres of the cerebrum, as those 
 parts are prolonged backward. 
 
 The transverse groove which divides the hitherto single pair of tubercles into an an 
 terior and a posterior tubercle on each side does not appear until about the sixth month, 
 at which time the cavity in their interior has been obliterated by the thickening of their 
 ■parietes.* 
 
 Comparative Anatomy of the Isthmus. 
 
 The pons Varolii and middle peduncles of the cerebellum exist only in the human subject 
 and in mammalia generally ; these structures, which may be regarded as forming the com- 
 missure of the cerebellum, are developed exactly in proportion to the size of the lateral 
 lobes of that orgem ; so that they attain their utmost development in the human subject, 
 and are smallest in rodentia. The pons and cerebellar peduncles do not exist in the re- 
 maining three classes of vertebrata (birds, reptiles, and fishes), because those animals 
 have no lateral lobes of the cerebellum. 
 
 The tubercula quadrigemina are less developed in man than in the lower animals. It 
 may even be said that the development of these tubercles is inversely in proportion to 
 that of the lateral lobes of the cerebellum and the hemispheres of the cerebrum. 
 
 The anterior tubercles are a little larger than the posterior in the human subject : in 
 the ruminants, solipeds, and rodentia, on the contrary, the anterior tubercles are twice 
 or three times as large as the posterior. In the carnivora the posterior are somewhat 
 larger than the anterior. 
 
 They are covered by the cerebrum in the human subject and the highest orders of 
 manomalia, but are in a great measure exposed in the rodentia and cheiroptera. 
 
 In birds, reptiles, and fishes, the tubercles are only two in number (the tubercula bige- 
 mina), and attain their maximum development : sometimes they are even larger than 
 the cerebral hemispheres ; they are hollow, and form true lobes, which are called the 
 optic lobes, because, in fact, the optic nerves arise exclusively from them. 
 
 In birds, the optic lobes are situated at each side of the base of the cerebrum. The 
 optic lobes of birds are not the thalami optici, as was at first believed : in this class of 
 animals the optic thalami are thrown forward. 
 
 In reptiles, the tubercula quadrigemina consist, as in birds, of two large, ovoid, and 
 contiguous lobes. 
 
 In fishes, it is extremely difficult to determine what are the tubercula quadrigemina ; 
 so much so, indeed, that the lobes of which they are composed have been taken some- 
 times for the cerebral hemispheres, and sometimes for the optic thalami. M. Arsaky 
 (De Piscium Cerebro) has successfully refuted both of these errors. 
 
 THE CEREBELLUM. 
 
 General Description. — External Characters and Conformation — Furrows, Lobules," Lamina, 
 and Lamellce. — Internal Conformation — the Fourth Ventricle, its Fibrous Layers, its In- 
 ferior Orifice, and its Choroid Plexus. — Sections of the Cerebellum, Vertical and Horizon- 
 tal. — Examination by Means of Water, and of the Hardened Cerebellum. — General View 
 of the Organ. — Development. — Comparative Anatomy. 
 
 The cerebellum {TrapEyKe<j>alic, Aristotle, 1 1, fig. 276 ; h h, fig. 280), or little brain, is 
 that part of the encephalon which occupies the right and left inferior occipital fossae. It 
 exists in all animals which have a cerebrum and spinal cord, and, therefore, in all the 
 vertebrata. 
 
 Cases of congenital absence of the cerebellum are extremely rare.t 
 Though for a long time neglected, the anatomical examination of the cerebellum was 
 commenced with considerable talent by Petit, of Namur {Lcttre d'un Medecin des Hopi- 
 tava du Roi, Namur, 1710), and Malacarne {Encephalotomia nuova Universale, Torino, 
 1780). Vicq d'Azyr and Chaussier have described its external conformation with ex- 
 traordinary accuracy ; and Reil, Gall, and Rolando, have more particularly investigated 
 its structure. 
 
 * In a fetus of seven months, I found the tubercula qnadrig-emina not yet divided into the nates and testes, 
 t Vide Anat. Pathol., avec fi^., for a case of absence of the cerebellum. 
 
#f§ NEUROLOGY. 
 
 The External Characters and Conformation of the Cerebellutn. 
 
 Situation. — The cerebellum is enclosed between the inferior occipital fossae and the 
 process of the dura mater, called the tentorium cerebelli. It is placed {see fig. 282) at 
 the top of and behind the spinal cord, and the isthmus of the encephalon. It is covered 
 by the cerebrum in the human subject only, whence the name cerebrum inferius. It is 
 posterior to the brain in the lower animals, and is therefore called cerebrum posterius. 
 
 The dura mater, the arachnoid, and the pia mater form a threefold investment around 
 it, the arrangement of which has been already described. 
 
 Size and Weight. — The cerebellum is larger in man than in any other species. It has 
 been stated by Cuvier, that its size in the human subject is so exactly proportioned to 
 that of the brain, that correct tables may be formed of their relative weights ; but it ap- 
 pears to me that facts are opposed to this view. 
 
 The mean weight of the cerebellum, including the pons Varolii and medulla oblongata, 
 is from four to five ounces ; the proportion between the cerebrum and cerebellum may 
 be estimated approximately to be as 7 to I.* 
 
 According to Gall and Cuvier, the cerebellum of the female is proportionally larger 
 than that of the male. Gall believes that its size is in a direct ratio with the energy of 
 the generative function, and that this is indicated externally by the relative size of the 
 inferior occipital protuberances.! 
 
 The cerebellum is proportionally much smaller in the infant than in the adult ; the 
 relation between the cerebrum and cerebellum in the infant is as 20 to 1. 
 
 Density. — The consistence of the cerebellum has been much studied by anatomists, 
 who are far from being agreed upon this subject. The great difficulty depends upon the 
 ■want of accurate means of estimating its consistence. In fact, it may be readily con- 
 ceived that the conversion of its substance into a pulp, by letting weights fall upon it 
 from a determinate height, is at once a most inconclusive and almost inapplicable meth- 
 od of ascertaining the point. Another source of difficulty consists in the fact that the 
 cerebellum is not homogeneous ; so that results obtained in reference to the gray matter 
 do not apply to the white substance. Out of fifty cerebella which Malacarne compared 
 •with the corresponding brains, twenty-three were softer than the brains in both the me- 
 dullary and cortical substances ; in thirteen the cortical substance was equally firm, but 
 the medullary substance more consistent and elastic than that of the brain ; ten were 
 more dense in texture, and the remaining five were much harder than the corresponding 
 brains. In some cerebella one of the hemispheres was much more firm than the other. 
 
 The results of my observations are, that the medullary centre of the cerebellum is of 
 a firmer consistence than that of the cerebrum ; that the gray substance of the cerebel- 
 lum is softer than that of the cerebrum; and that the gray substance of the former be- 
 comes softened in the dead body with such extreme rapidity, that it is difficult to meet 
 with a cerebellum in which this substance is in the normal state. 
 
 Form. — The general outline of the cerebellum is that of an ellipsoid flattened from 
 above downward ; its long diameter is transverse, and measures from three and a half 
 to four inches ; its antero-posterior diameter is from two to two and a half inches, and 
 its vertical diameter two inches in the thickest part, and about six lines in the thinnest 
 part, that is, at its circumference. The figure of the cerebellum may also be compared 
 to that of a heart on playing cards, the notch of which is directed backward, and the 
 truncated apex forward ; or, rather, as was done by the old anatomists, to two flattened 
 spheroids, united together at their points of contact. 
 
 The cerebellum is perfectly symmetrical, but yet a marked difference between the 
 right and left half of this organ is not unfrequently observed.} 
 
 The cerebellum presents for our consideration an upper and a lower surface, and a 
 circumference. 
 
 The upper surface {h h, fig. 280) presents along the median line an antero-posterior em- 
 inence (d), which is rather prominent in front, but gradually disappears as it extends 
 backward : it is named the superior vermiform process {vermis superior). This eminence, 
 which covers the valve of Vieussens and the tubercula quadrigemina, should be regard- 
 ed, as Malacarne states, as the upper part of the median lobe of the cerebellum. 
 
 On each side {h h) the upper surface of the cerebellum forms an inclined plane. This 
 surface is separated from the posterior lobe of the cerebrum by the tentorium cerebelli. 
 
 * Chaassier says, " In a considerable number of comparative experiments, we sometimes found that the adult 
 cerebellum was -^th or ^th, and at other times, but rarely, -pn th or -ryth the weight of the cerebrum. In the 
 
 infant, at birth, we found it to be yV*-^' tV*^' PT*''' "^V^'' ^'^i ""''' '" °"® '^*'^» *^®" 3 S*^ '^^ ^"^'^^ weight 
 of the brain." — {De VEncephale,^.71.) 
 
 + In my opinion, this idea can only be regarded as an ingenious hypothesis. The aptitude for the generative 
 act is not dependant upon the cerebellum, for all invertebrate animals are destitute of this organ ; and in cer- 
 tain vertebrata, where the generative orgasm is quite remarkable, the cerebellum is extremely small. Some 
 observations, however, are quoted, which appear to show that diminution of the occipital protuberance ha» 
 followed extirpation of the corresponding testicle : but it must first be proved that these observations are cor 
 red ; for example, that the inequality of the occipital protuberances did not exist previously to the castration, 
 
 t In four cases which have come under my own observation, atrophy of the right hemisphere of the cerebrum 
 coexisted with atrophy of the left hemisphere of the cerebellum ; I am, therefore, led to conclude that there 
 ve certain intimate relations between the opposite hemispheres of these two portions of the encephalon. 
 
THE FURROWS, LOBULES, ETC., OF THE CEREBELLUM. 717 
 
 The lower surface of the cerebellum {figs. 275, 276) is received into the concavity oi 
 the occipital fossae, to which it is exactly fitted: it is divided into. two rounded, lateral 
 halves {h, fig. 275), the lobes of the cerebellum, by an antero-posterior fissure (a to n), 
 the great median fissure of the cerebellum (vallecula, Haller). 
 
 The back part of the cerebellum is completely subdivided by this fissure {see fig. 282), 
 which receives the falx cerebelli ; in front, the fissure opens into a wide furrow, into 
 which the medulla oblongata is received {see fig. 276) ; in the middle of the fissure is a 
 lozenge-shaped interval, at the bottom of which is seen the base of a pyramidal emi- 
 nence {a h c, fig. 275), divided transversely pig. 275. 
 into rings like a silkworm, and n£imed, ac- 
 cordingly, by the older anatomists, the in- 
 ferior vermiform process {vermis inferior, 'pyr- 
 amid, of Malacarne). This eminence is de- 
 veloped into four prolongations or branch- 
 es, arranged in the form of a cross ; the 
 posterior prolongation (c) is tapering, an(: 
 occupies the back part of the great median 
 fissure ; the two lateral processes dip (on 
 each side of h) into the adjacent portion of 
 the fourth ventricle ; and the anterior (i) 
 tapers from behind forward, and terminates 
 in a mammillary enlargement (a), which is 
 free, and projects into the fourth ventricle. It has been unnecessarily distinguished from 
 the rest of the inferior vermiform process by Malacarne and Chaussier, under the name 
 of the laminated tubercle of the fourth ventricle {tubercle lamineux du quatrieme ventricule).* 
 
 The inferior vermiform process is merely the lower part of the median lobe of the cere- 
 bellum, of which the superior vermis constitutes the upper part. The superior vermis is 
 continuous, without any line of demarcation, with the two hemispheres of the cerebel- 
 lum, so that the upper part of that organ appears undivided. The inferior vermis, which 
 seems at first sight to be intended to separate the two hemispheres, nevertheless forms 
 the means of connexion between them, as may be easily seen by drawing them apart 
 from each other. 
 
 The circumference of the cerebellum is somewhat elliptical, or, rather, resembles the 
 heart upon playing cards ; behind and in the middle line it presents a notch (n), between 
 the convex margins of which a triangular interval is left, into which the falx cerebelli 
 and the internal occipital crest are received. At the bottom of this notch the surface 
 of the cerebellum is transversely grooved ; this part unites the superior to the inferior 
 vermiform process, and belongs to the median lobe of the cerebellum. 
 
 The rounded margins of the 7iotch are continuous with the circumference of the cere- 
 bellum. In front, the circumference of the cerebellum appears to be formed by the pons 
 Varolii {d,fig. 276) and middle cerebellar peduncles (m), which are in relation with the 
 posterior surface of the petrous portion of the temporal bones, and are therefore straight, 
 and form a truncated angle, which projects forward, and corresponds to the pons Varolii. 
 
 All the bundles of fibres which connect the cerebellum with the cerebrum and spinsd 
 cord enter at the anterior part of its circumference : thus, besides the middle peduncles 
 of the cerebellum, we find in this situation its superior peduncles (r, fig. 272), or pro- 
 cessus ad testes, and its inferior peduncles (cut at n), or processus ad medullam oblongatam, 
 to which we shall presently return. 
 
 The Furrows, Lobules, Laminae, and Lamellce of the Cerebellum. 
 
 The whole surface of the cerebellum is traversed by curved lines or furrows, which 
 are, for the most part, concentric and horizontal, but not very regular. 
 
 These furrows are not parallel, but are inflected towards each other, and intersect at 
 very acute angles. 
 
 They may be divided into four sets, according to their depth. The first set of furrows 
 are the deepest : they reach as far as the central nucleus, and divide the cerebellum into 
 segments or lobules {g, h, I, fig. 275). omj 
 
 These segments are divided into secondary segments by the second set of furrows. 
 
 The secondary segments are again subdivided into lamiruB or folia, and these lamina 
 into lamella, by two sets of yet smaller furrows. 
 
 Pourfour du Petit, Malacarne, and Chaussier have studied the sepnents, laminae, and 
 lamellae of the cerebellum with great care, and have even counted them. The differen- 
 ces in their results! are not so much a proof of varieties in the structure of the organ 
 as of the want of some uniform method of enumeration. 
 
 * [The inferior vermiform process is usually described as consisting of three portions : the pyramid (.c,fig. 
 275), the uvula (6), and the nodulus (o).] 
 
 t Winslow admitted 3 lobules, Collins 6, Ponrfour du Petit 15, Malacarne 11, and Chaussier 16. Chaus- 
 sier counted 60 laminae, and from 600 to 700 lamellae ; Malacarne had previously counted from 700 to 800 la- 
 mellae. It is a very curious fact that Malacarne only found 324 lamells in an individual labouring under 
 mental alienation 
 
718 NEUROLOOV 
 
 The segments which occupy the circumference of the organ are the largest : they rep- 
 resent segments of an ellipsoid, and are very broad in the middle, and narrowed at each 
 extremity. The segments of the upper surface are concentric, and their curvature cor- 
 responds to that of the entire cerebellum. The segments of the lower surface are also 
 concentric in each half or lobe of the cerebellum, but the curves of one side are inde- 
 pendent of those of the other. 
 
 The laminae or folia of the cerebellum are applied to each other like the leaves of a 
 book ; they are separated from each other in their whole length, and are attached to the 
 rest of the cerebellum by their adherent borders only. The lamellae, however, are ar- 
 ranged in a different manner, for they pass from one lamina to another, and even from 
 segment to segment. In fact, if the segments of the cerebellum be drawn asunder, the 
 furrows between them are seen to be traversed obliquely by a great number of lamellae, 
 which extend from one segment to another. 
 
 The arrangement of the segments, laminae, and lamellae in the median line deserves 
 particular attention. Opposite the superior vermiform process, they are not interrupted, 
 but are merely bent slightly, so that the middle portion of each of the anterior segments 
 is, as it were, drawn forward, so as to describe a curve, having its concavity turned 
 backward. Upon this surface some slight peculiarities are observed in the arrangement 
 of the parts. Along the median line there seems, indeed, to be an interchange of lam- 
 inae and lamellae, some of each of which become thin, and end in points, from which oth- 
 ers appear to originate. 
 
 Opposite the inferior vermiform process the two hemispheres of the cerebellum are 
 connected together by means of the latercd prolongations of that process. But in front, 
 i. c, opposite the medulla oblongata, the two hemispheres of the cerebellum are perfect- 
 ly distinct from each other (see Jig. 275). From these facts we may estimate to what 
 extent the comparison is correct which was drawn by HaUer between the superior ver- 
 miform process and the corpus callosum. 
 
 At the back part of the cerebellum, opposite the notch in that situation, the two hem- 
 ispheres are connected by means of certain small transverse rings, of which we have 
 already spoken. 
 
 The superior and inferior vermiform processes and the portion situated at the bottom 
 of the notch constitute together the middle lobe of the cerebellum, which Gall and Spurz- 
 heim named the primitive or fundamental part of the cerebellum, because it exists in all 
 vertebrata, and because, in a great number of them (as in birds, reptiles, and fishes), 
 where the lateral lobes of this organ are altogether wanting, it constitutes the entire 
 cerebellum. It is well to add, that the lateral lobes are relatively larger, and the medi- 
 an lobe smaller in man than in other mammalia. 
 
 A rudimentary median lobe, and very large lateral lobes, are the characteristics of the 
 human cerebellum, while a very large median lobe, and rudimentary lateral lobes, form 
 the characters of the cerebellum of the lower animals. 
 
 All the segments of the cerebellum, of which there are from ten to twelve, might with 
 propriety be distinguished by particular names. The following segments, however, re- 
 quire special mention : the segment or lobule of the circumference {I, fig. 275), which is the 
 largest ; the lobules of the medulla oblongata (lobuli medullae oblongatae), which are situa- 
 ted behind that part (see fig. 276), are concave on their internal surface, which is accu- 
 rately adapted to the medulla, and convex on their external and posterior surface, which 
 dips slightly into the foramen magnum. These lobules (removed from f,fig. 275), which 
 have been noticed by all qnatomists, are separated from one another by the inferior vermi- 
 form process (the uvula, b), and each of them terminates in front and on the inner side by a 
 mammillated extremity (called the amygdala or tonsil), which partially fills up the fourth 
 ventricle. The other inferior segments of each lobe of the cerebellum describe concen- 
 tric curves around this segment. The lobule of the pneumogastric nerve (rf) is a sort of 
 prominent tuft (flocculus), situated (w, fig. 276) behind the pneumogastric nerve (8), and 
 below the facial and auditory nerves (7). 
 
 The Internal Structure of the Cerebellum. 
 It is convenient to include under this head the description of the fourth ventricle, as 
 well as that of the substance of the cerebellum. 
 
 The Fourth Ventricle. 
 
 Dissection. — Divide the median lobe of the cerebellum vertically ; make a vertical 
 section of the pons along the median line ; draw asunder the medulla oblongata from 
 the cerebellum. By means of the first section the anterior wall of the fourth ventricle is 
 exposed, and by the second its posterior wall ; by drawing apart the medulla oblongata 
 and cerebellum, the ventricle is reached by its inferior extremity, and its whole depth 
 can be seen. It is important to examine the fourth ventricle in all its aspects. 
 
 The fourth ventricle {c to y, fig. 282) is that rhomboidal cavity situated between the 
 medulla oblongata and isthmus of the encephalon (? n), which forms its anterior wall, 
 and the cerebellum (w), which constitutes its posterior wall. The old anatomists follow- 
 
THE FOURTH VENTRICLE. 719 
 
 ea Galen m calling it the ventricle of the cerehellum. Tiedemann speaks of it as the first 
 ventricle, because it is developed before the other ventricles, and is constant in all mam- 
 malia. 
 
 The fourth ventricle terminates in a point below, expands considerably in the middle, 
 and is again contracted at its upper part, where it becomes continuous with the third 
 ventricle. 
 . We shall consider separately its anterior and posterior walls. 
 
 The anterior or inferior wall is formed by the posterior surface of the medulla oblonga- 
 gata (see^. 271) and that part of the upper surface of the isthmus of the encephalon 
 which corresponds to the pons. In shape it resembles a lozenge or diamond, truncated 
 at its upper point ; the upper borders of the lozenge being represented by the superior 
 peduncles of the cerebellum (r to g), and the lower by the restiform bodies (e) : the poste- 
 rior surface of the re-enforcing fasciculi {faisceaux innomines) of the medulla oblongata 
 constitutes this anterior wall, which is lined by a dense and easily separable membrane. 
 
 The 'posterior or superior wall represents a vaulted roof, which is formed above by the 
 superior peduncles of the cerebellum (r to g) and the valve of Vieussens {l, fig. 271 ; I, 
 fig, 275 ; g w, fig. 282), lower down by the cerebellum (w), and below by a fibrous mem- 
 brane, continuous with the neurilemma of the spinal cord. 
 
 Opposite the middle, i. e., the broadest part of this posterior wall (see_^. 275), are sit- 
 uated three mammillary projections — one median and two lateral : the first (b, the uatu- 
 la) is the anterior segment of the median lobe of the cerebellum ; the other two (the 
 amygdcdae) are formed by the innermost laminae of the lobule of the medulla oblongata 
 (cut away at/). These latter are not bathed in the fluid of the ventricle, but are sep- 
 arated from it by the fibrous membrane lining that cavity. 
 
 The median mammillary projection (6), named by Malacarne and Chaussier the lami- 
 nated tubercle of the fourth ventricle, resembles a movable valve. It is attached to the 
 cerebellum by two white pedicles, which pass outward and backward upon the lateral 
 processes of the crucial eminence formed by the inferior vermis. Connected to its an- 
 terior extremity (the nodulus, a) are seen two broad folds {semilunar folds, e), which arise 
 from it, one on each side, and become continuous with the roots of the corresponding 
 sub-peduncular lobules or flocculi {d). 
 
 These folds, which are quite distinct from the valvulse Tarini, are extremely thin and 
 semi-transparent ; their convex borders adhere to the back part of the fourth ventricle ; 
 the concave margins and their two surfaces are free.* The two semilunar folds and 
 the intermediate projection, or the nodule, may be compared to the soft palate, the mam- 
 millary projection representing the uvula, t 
 
 Opposite the upper angle of its rhomboidal cavity, the fourth ventricle {v, fig. 282) be- 
 comes continuous with the third (Z), through a canal, named iter a tertio ad quartum ven- 
 triculum, or the aqueduct of Sylvius, which, however, had been described by Galen : this 
 aqueduct is formed beneath the tubercula quadrigemina {f g) and the valve of.Vieus- 
 sens {g w). 
 
 The lateral angles of the fourth ventricle are much elongated, and reach as far as op- 
 posite the inner extremity of the corpus dentatum of the cerebellum. 
 
 At the inferior angle (y) of the fourth ventricle is situated a fibrous layer, which con- 
 stitutes its floor, and also an orifice of communication between the ventricle and the 
 sub-arachnoid space. 
 
 The Fibrous Layers of the Fourth Ventricle. 
 
 Floor of the Fourth Ventricle. — On carefully drawing the medulla oblongata away from 
 the cerebellum, a fibrous layer is seen extending from one to the other, and forming, as 
 it were, the floor of the fourth ventricle. This layer, which is continuous with the neu- 
 rilemma of the medulla oblongata, consists of three very distinct parts : of a median 
 portion, shaped like a triangular tongue, which passes horizontally backward, and is ap- 
 pUed to the anterior extremity of the inferior vermis, to which it adheres ; and of two 
 triangular lateral portions, which form the sides of the orifice of the fourth ventricle, and 
 which were described by Tarin as the valves of the base of the fourth ventricle. 
 
 Besides this fibrous layer, there is another on each side, situated behind the roots of 
 the pneumogastric nerve : these layers adhere to those roots, and we shall therefore 
 name them the fibrous layers of the pneumogastric nerves ; they close the fourth ventricle 
 upon the sides of the medulla oblongata, and when they are removed the ventricle is 
 quite open. They extend from the restiform bodies to the lobules of the pneumogastric 
 nerves, and are prolonged upward upon the auditory nerves. 
 
 The Inferior Orifice of the Fourth Ventricle. 
 If the medulla oblongata and cerebellum be drawn apart, there is seen in the median 
 
 * [These two folds constitute the posterior medullary velum of the cerebellum, the valve of Vieussens form- 
 ing the anterior velum.] 
 
 t [The terms uvv.la and amygdalie, or tonsils, have, as already noticed, been applied to another series ot 
 three bodies which are arranged behind the nodule, the flocculi and the posterior vela, and consist of the lam- 
 inated tubercle of the fourth ventricle, and of the inner portions of the lobes of the medulla oblongata (see p. 
 718).] • s{ vj' »»i»<»««>n»^-"iTiv r- - -■ 
 
71^ NEUROLOGY. 
 
 line, between the inferior cerebellar arteries, a lozenge-shaped opening (at y, fig. 282), 
 bounded, in front, by the base of the calamus scriptorius ; behind, by the anterior pro- 
 longation of the inferior vermiform process, which is covered by the median tongue of 
 the fibrous layer ; and upon the sides, in front, by the ragged edges of the lateral por- 
 tions of the fibrous layer, and by the internal surfaces of the lobules of the medulla ob- 
 longata. 
 
 This opening was pointed out by M. Magendie as establishing a communication be- 
 tween the general ventricular cavity and the sub-arachnoid space. It has been asked, 
 Is it a natural opening, or is it produced accidentally by the very means employed in its 
 demonstration 1 The following are the arguments on both sides of the question : 
 
 In opposition to the existence of an opening in this situation, it is urged that the mar- 
 gin of the orifice has none of the characters of that of a natural opening, the edges of 
 which are generally smooth and rounded ; but in this orifice they are lacerated, and there 
 is almost always some membranous shreds at the point of the calamus scriptorius. If 
 the median triangular tongue of the fibrous layer, which is applied to the inferior vermis, 
 be detached, it is seen to be merely a flap of that membrane, the size of which exactly 
 corresponds to that of the opening, so as to close it completely. This point may be ren- 
 dered still more evident by tracing the membrane from before backward, after having di- 
 vided the pons and medulla oblongata. 
 
 Again, the fibrous layer, which forms the floor of the fourth ventricle, is entire in the 
 dog and sheep ; I have found it in the same condition five or six times in the human 
 subject ; and if it be objected that, in this case, there might have been an accidental ob- 
 literation of the opening, I could answer that there was no trace of disease, either in the 
 cerebro-spinal axis, or in the membranes. 
 
 I may also mention that, in several cases of chronic hydrocephalus, several pounds ol 
 fluid were found in the ventricles, and none whatever in the sub-arachnoid space. 
 
 Lastly, in the brains of several infants, who had died with all the symptoms of acute 
 ventricular hydrocephalus, I have found the lateral ventricles very large, but empty ; and 
 in these cases, it has occurred to me that the fibrous layer might have been perforated 
 opposite the inferior angle of the fourth ventricle, and have thus allowed the fluid to 
 escape, which, in the greater number of cases, is retained by this layer within the ven- 
 tricular cavity. 
 
 Such are the facts which appear to me to militate against the idea of the existence of 
 an opening in the floor of the fourth ventricle ; but, on the other hand, if we consider 
 that, in an immense majority of instances, whatever care may be taken in removing the 
 brain from the cranium, we always find this opening both in the foetus and in the adult ; 
 that in apoplectic effusions into the ventricles, we always find some bloody serum in the 
 sub-arachnoid space ; and that if a coloured fluid be injected into the ventricles of the 
 cerebrum, or into the sub-arachnoid space around the cord, it will in either case pass 
 freely /rom one into the other, we shall be led to conclude that there is a regular com- 
 munication between the cavity of the ventricles and the sub-arachnoid space, and that 
 the orifice just described is the channel of communication between them.* 
 
 The Choroid Plexuses of the Fourth Ventricle. 
 
 The choroid ■plexuses of the fourth ventricle are two in number ; they commence one on 
 each side, by a very slender extremity, upon the anterior surface of the sort of fibrous 
 tongue which is attached to the inferior vermis ; from this point they pass in a diver- 
 ging course upward, are then inclined outward, turn round the sides of the median emi- 
 nence of the fourth ventricle, pass horizontally outward behind the restiform bodies, and 
 then behind the fibrous layer of the corresponding pneumogastric nerve, where they be- 
 come considerably enlarged, and at length terminate upon the sub-peduncular lobes. 
 
 The inner surface of the fourth ventricle is smooth, in consequence of being lined by 
 a membrane resembling a serous membrane, which is much stronger over the posterior 
 surface of the medulla oblongata than at any other point. 
 
 Sections of the Cerebellum. 
 
 On cutting through the cerebellum, it is found to be composed (see figs. 273, 274) of 
 two substances, an external cortical or gray substance, and a central or medullary substance, 
 which is white ; the gray substance is soft, and is almost always torn off with the mem- 
 branes, however slightly the cerebellum may be altered by decomposition. The white 
 substance is compact, and resists a tolerably firm pressure.! 
 
 Between the gray and white substances there is seen, upon a section of the cerebellum, 
 a narrow yellowish band or streak, which depends on the existence of a layer of a yellow 
 substance, of much greater firmness than the gray matter, and strongly adherent to the 
 white substance. By laceration the gray matter is destroyed, and this yellow layer is 
 exposed. There are, therefore, three substances in the cerebellum : the gray, the yellow, 
 
 ' See note on the sub- arachnoid space (p. 690). 
 
 t For an account of the minute structure of these substances, see note, p. 701. 
 
SECTIONS OF THE CEREBELLUM. 781 
 
 and the white. I would compare the yellow layer of the cerebellum to the yellow folded 
 membrane of the olivary bodies.* 
 
 A question liere arises, What is the proportion between the gray and the white mat- 
 ter ? The most superficial examination of the cerebellum will show that the gray mat- 
 ter predominates ; and this can be clearly demonstrated by macerating the cerebellum 
 for several days. The gray matter, which is more easily decomposed, becomes con- 
 verted into a pulp, and the remaining nucleus of white substance scarcely represents a 
 third, eitlier of the weight or bulk of the cerebellum. 
 
 We shall now proceed to describe the appearance of vertical and horizontal sections 
 of the cerebellum. 
 
 Vertical Sections. 
 
 Upon longitudinal vertical sections of the cerebellum, the gray and white substances 
 present a very elegant arrangement, known by the picturesque name of the arbor vita ; 
 a title derived either from the importance which has been attached to this structure, or 
 from its resemblance in figure to the foliage of the tree so called. Upon a section maule 
 through the median line, the arbor vita of the middle lobe {w, fig. 282) is seen ; and upon 
 one made on either side, the arhor vita of the lateral lobes. 
 
 The arbor vita of the median lobe consists of a central nucleus of white substance, of a 
 triangular form, from which two principal branches proceed : one inferior, which is dis- 
 tributed to the whole of the inferior vermis and the back part of the median lobe ; the 
 ' other superior, which passes into the whole of the superior vermis. These two branches 
 subdivide into six others, which vary in direction, length, and thickness, and are them- 
 selves subdivided into still smaller branches, and these, again, into the smallest ramifica- 
 tions. A slight enlargement of the white substance is always observed opposite the 
 points of division. 
 
 A very thin yellowish layer, and outside this a layer of gray matter, about a line in 
 thickness, covers each of the ramifications of the white substance, and thus forms the 
 lamellie, laminae, and segments of the median lobe. 
 
 This section enables us to prove the existence of the middle lobe of the cerebellum 
 and the continuity of the superior and inferior vermis ; it also shows the general form 
 of the middle lobe, which is rotate or wheel-shaped (the anterior extremity of the in- 
 ferior vermis, i. e., the nodule, comes into contact with the valve of Vieussens) ; the 
 number and arrangement of the segments, laminae, and lamellae of the cerebellum; and, 
 lastly, the nature of the valve of Vieussens, which is nothing more than the uppermost 
 subdivision of the central nucleus, and may be regarded as one half of a lamella of the 
 cerebellum. 
 
 The Arbor Vita of the Lateral Lobes. — A vertical section from the middle peduncles of 
 the cerebellum towards the circumference displays the arbor vitae of the lateral lobes. 
 
 In the centre of each lobe is seen a white central nucleus, from which fifteen or six- 
 teen principal branches are given off, to form the nuclei of a corresponding number of 
 the segments. These branches are subdivided into secondary branches, and those into 
 the ultimate ramifications. A yellowish layer covers each of these successive divisions, 
 and upon that a gray layer, about a line in thickness, is accurately moulded. 
 
 Upon sections of this kind it is easily seen that the segments of the cerebellum are 
 very unequal in size, in direction, and in their manner of division ; that the superior 
 segments are the smallest, the segments of the circumference the largest,! and the in- 
 ferior segments of an intermediate size ; that there is no vacant space between the seg- 
 ments, but that both laminae and lamellae occupy the intervals ; and, lastly, that all of 
 these segments curve forward upon themselves, so as to form a series of horizontal 
 wheels or circles, the plane of which is at right angles to that of the wheel-shaped 
 mass of the middle lobe. 
 
 In the centre of the white nucleus of each half of the cerebellum is the corpus rhom- 
 boideum, or corpus dentalum :% these bodies are of an ovoid form ; their yellowish invest- 
 ing layer is dense, and folded backward and forward upon itself, and exactly resembles 
 that of the olivary bodies ; and I have been accustomed to speak of these bodies as the 
 olivary bodies of the cerebellum. Gall and Spurzheim regarded them as ganglions of 
 re-enforcement, and called them tlie ganglions of the cerebellum. Their shortest or verti- 
 cal diameter is about one third of their long or horizontal diameter ; in one case, where 
 the latter was fifteen lines, the former was five lines : moreover, the size of the corpora 
 dentata of the cerebellum varies in different subjects, and is in proportion to the size of 
 
 * Rolando ( Ossemazioni suV Cervetetto, p. 187, 1823) appears to me to have been the first to establish the fact 
 of the existence of three substances : the medoHare, the cinereo rossigna, and the cinerea esterna e corticate. 
 
 t The segment of the circumference, which is the largest of all, immediately divides into two smaller seg- 
 ments ; it has liecu iucorrecUy stated that there is a horizontal fissure along the circumference of the cere- 
 bellum, extending from one of the middle peduncles to the other. 
 
 t In order to divide the corpus dentatum, the section must be made opposite the corresponding inferior pe- 
 duncle (if the cerebellum. I would recommend that one section be made to extend through the corpus denta- 
 lum of the cerebellum, and also through the olivary body, so that some idea may be formed of the analogy be- 
 tween these two |>arts. 
 
 4Y 
 
NEUROLOGY. 
 
 the lateral lobes of that organ : they are, therefore, much less developed in the lower 
 animals than in man. 
 
 The peduncles of the cerebellum are six in number, three on each side, namely, a supe- 
 rior, a middle, and an inferior ; they all originate, or, it may be said, terminate in the cen- 
 tral nucleus. 
 
 The superior peduncles of the cerebellum are generally known as the processus cerebelli 
 ad testes ; ttiey are seen (r, fg. 280) in front of the superior vermiform process, and seem 
 to pass up to the tubercula quadrigemina. We shall afterward see that this is only ap- 
 parent. 
 
 The inferior peduncles (processus cerebelli ad medullam oblongatam) are, in fact, the resti- 
 form bodies ; they establish a direct and intimate communication between the cerebel- 
 lirni and the spinal cord. 
 
 Lastly, the middle peduncles {m, fig. 276), which are anterior to the two preceding sets, 
 occupy the fore part of the circumference of the cerebellum, and are continued into the 
 pons Varolii without any line of demarcation. They are called also the cerebellar pedun- 
 dea {processus cerebelli ad potitem), and the crura or legs of the medulla oblongata. 
 
 Horizontal Sections. 
 
 Horizontal sections of the cerebellum have been studied with very great care, and have 
 been well figured by Vicq d'Azyr ; they show that the dimensions of the central nucleus 
 are much greater in the horizontal than in the vertical direction.* 
 
 Upon these sections, which should be made parallel to the upper surface of the cere- 
 bellum, is seen the relative disposition of the laminae, which are sometimes parallel and 
 sometimes oblique in reference to each other, and which either extend around the entire 
 circumference of the organ, or terminate in tapering extremities and again commence, 
 and pass from one segment to another. 
 
 Lastly, these horizontal sections show the continuity of the right and left lobes of the 
 cerebellum by means of the middle lobe. In this middle lobe the lamellae are more ir- 
 regular than in the lateral lobes ; they intersect each other at various angles, and be- 
 come again united into new combinations, so that several anatomists have admitted the 
 existence of a true decussation in this middle portion of the cerebellum. 
 
 The middle lobe also has its medullary centre, which connects the lateral medullary 
 centre in such a manner that, by a successful section, a sort of cerebellar centrum ovale 
 is obtained, analogous to the centrum ovale of Vieussens in the cerebrum. 
 
 Examination of the Cerebellum by means of a Stream of Water, and Dissec- 
 tion of the Hardened Cerebellum. 
 A stream of water directed upon vertical sections of the cerebellum decomposes the 
 white nucleus of each lateral lobe into a great number of extremely thin leaves, which 
 constitute the different laminae or lamellae of the cerebellum. All these laminae and la- 
 mellae terminate in the central nucleus of the corresponding lobe. Each lamella is fan- 
 shaped, its adherent border being very narrow, concave, and applied io the central nu- 
 cleus, with which it is evidently continuous, while its convex margin corresponds to the 
 surface of the cerebellum. The arrangement of these lamellae is very beautiful and cu- 
 rious : some of them ascend to form the segments, lamina, and lamellae of the upper 
 surface of the cerebellum ; others descend to form the corresponding parts of the lower 
 surface, and the intermediate ones pass horizontally to the circumference, and are dis- 
 posed in a similar manner. Opposite each point of subdivision there seems to be an en- 
 largement of the white substance, but this depends not upon an actual increase of that 
 substance, but upon the divergence of the lamellae. 
 
 The structure of the cerebellum, therefore, considered generally, is laminated. From 
 the central white nucleus proceed innumerable lamina;, which, though in juxtaposition, 
 are never blended together, and which form groups, that are themselves subdivided again 
 and again, like the branches of a tree, the ultimate lamella always containing at least 
 two leaflets. Can anatomy teach us anything beyond this laminated arrangement 1 In 
 each lamella certain radiated striae are seen ; and it may be asked. Whether these prove 
 the existence of a linear or fibrous structure 1 It is certainly true that the lamellae may 
 be divided in the direction of these striae, but it is far from being evident that they con- 
 sist of linear fibres. 
 
 In the central nucleus, the laminae, being more firmly pressed together, are separated 
 by the stream of water with greater difiiculty than the laminae near the surface : the 
 corpora dentata of the cerebellum are peculiarly firm. The stream of water insinuates 
 itself into these bodies opposite their internal extremity, which appears to be naturally 
 open, and divides them into two halves, a superior and an inferior. It is then seen that 
 the dentated appearance of their section results from the reduplication of the dense yel- 
 lowish layer in which they are enclosed ; also, that the white substance penetrates into 
 the interior of these bodies at their internal surface, accompanied by a great number of 
 
 * In each lobe of the cerebellum there is a medullary centre, that is, a spot in which the section of the whit* 
 substance is larger than at other points. 
 
GENERAL VIEW OF THE CEREBELLUM. 723 
 
 vessels ; and that this white substance is arranged in lamellae, which terminate at three 
 different points of the yellowish layer, so that each of the corpora dentata resembles a 
 small cerebellum. 
 
 Examination of the Hardened Cerebellum. — The examination of the cerebellum, when 
 hardened by alcohol, or by boiling in oil, or salt and water, or by maceration in a solu- 
 tion of salt and bichloride of mercury, of the strength recommended by Rolando, confirms 
 all the results which have been obtained by the preceding method of investigation. 
 
 These modes of preparation, moreover, enable us to examine more completely than in 
 any other way the relations of the central nuclei of the lobes to the peduncles of the cere- 
 bellum. It is seen most distinctly that these peduncles (m n. Jig. 273 ; n r, fig. 274) 
 emerge from or terminate in the central nuclei ( p p), but it is very difficult to ascertain 
 their precise arrangement within the nuclei. All that we know is the fact that, as soon 
 as they emerge from the central nuclei, they assume a fasciculated character, and that 
 all the lamellae and laminae of the cerebellum seem to terminate in the fibres of the mid- 
 dle peduncles. 
 
 General View of the Cerebellum. 
 
 From the preceding statements we may draw the following conclusions : The cerebel- 
 lum consists of two lateral lobes and a middle lobe ; the lobes are formed by a consider- 
 able number of segments, which are subdivided into smaller segments, and these into 
 laminae and lamellae ; each lobe contains a central medullary nucleus, upon which all the 
 segments rest, and which constitutes the termination or the origin of the several pedun- 
 cles ; the substance of these peduncles is fibrous or fasciculated, and that of the central 
 nucleus has a similar character, but not so well marked ; the medullary substance of 
 each segment is formed by laminae applied to each other, but not actually continuous ; 
 each of these laminae is fan-shaped, and those which constitute the central nucleus of 
 each segment become separated from each other to form the secondary segments, the 
 laminae, and the lamellae ; the ultimate lamellae of the cerebellum consist of two leaflets 
 of white matter covered externally by a very thin yellowish layer, which is itself cover- 
 ed by a rather thick layer of gray matter ;* the corpora dentata, or olivary bodies of the 
 cerebellum, consist of fibres or laminae of medullary substance, which are spread out so 
 as to terminate at different points upon the inner surface of the dense yellow membra- 
 nous layer which constitutes their external investment. 
 
 A very ingenious explanation of the structure of the cerebellum has been proposed by 
 Gall, and is now rather generally adopted. 
 
 The opposite directions of the inferior and middle peduncles of the cerebellum sug- 
 gested to him the idea of diverging and converging fasciculi, and to this he has added his 
 theory regarding the ganglia, which he considered as apparatuses of re-enforcement, that 
 is to say, as points of origin for new fasciculi. 
 
 According to Gall, then, the inferior peduncles of the cerebellum or the restiform bod- 
 ies (n,fig. 274), which he calls the primitive fasciculi of the cerebellum, are the roots, or 
 fasciculi of origin of the cerebellum. After they have penetrated a few lines into the 
 substance of the organ, they meet with and join the corpus dentatum, which Gall regards 
 as a true ganglion, or apparatus of origin and re-enforccment for a great part of the nervous 
 mass of the cerebellum. According to him, a principal nervous fasciculus corresponds to 
 each of the folds of the corpus dentatum, from which ganglion arise all those prolonga- 
 tions of medullary substance which, together with the gray matter upon them, consti- 
 tute the middle and lateral lobes of the cerebellum. 
 
 Besides the preceding fasciculi, which are named by Gall the diverging fasciculi, and 
 are said by him to constitute the formative system of fibres, there are certain converging 
 fasciculi, which constitute the uniting system of fibres, or the commissures of the cerebellum. 
 These are supposed to have no direct connexion either with the primitive fasciculi or 
 the corpus dentatum, but to emanate from the gray matter upon the surface of the cere- 
 bellum, and to pass in different directions (p q, fig. 273) between the diverging fasciculi, 
 so as to enter into and constitute the middle peduncles of the cerebellum (m) and the 
 pons Varolii, which Gall regarded as forming together the commissure of the cerebellum. 
 
 The superior peduncles of the cerebellum (?•', fig. 274) he considered as fasciculi o*" 
 communication between the middle median lobe of the cerebellum and the corpora quad 
 rigemina, and the valve of Vieussens as the commissure of these peduncles. 
 
 We can only regard Gall's view concerning the structure of the cerebellum as an in- 
 genious speculation. Why should the inferior fasciculi be the roots or primitive bundles 
 of the cerebellum rather than the superior 1 Who has seen the re-enforcement of these 
 primitive fasciculi in the corpus dentatum 1 Why should the corpus dentatum be regard- 
 ed as a ganglion 1 Whence is this distinction between converging and diverging fasci- 
 culi 1 1 and, finally. Why are figure and metaphor employed in reference to strictly ana- 
 tomical questions 1 
 
 * [The white substance of the laminae is said to consist of two sets of fibres — one coming from the central 
 mass, and passing up the centre of the laminie, and the other set lying; upon the first, and passing from one 
 lamina to another.] 
 
 * " These converging fibres," says Tiedemann (French translation by Jourdan, p. 169j, " are merely chimer- 
 
724 NEUROLOGY. 
 
 Another theory regarding the structure of the cerebellum has been offered by Rolan- 
 do, who, by combining the results derived from an examination of the human cerebellum, 
 when hardened in a strong saline solution, with those furnished by the anatomy of the 
 brain of the shark, and those obtained by studying the development of the brain of the 
 fowl, was led to regard the human cerebellum as formed by the folding and refolding upon 
 themselves of the parietes of a large bladder or vesicle, so as to give rise to innumera- 
 ble laminae.* 
 
 The facts we have already stated sufficiently refute this hypothesis. It is quite cer- 
 tain that the cerebellum is formed by the union of one middle and two lateral lobes : the 
 lobes themselves are composed of a considerable number of segments, which are subdi- 
 vided into smaller segments, laminae, and lamellae. The general structure of the cere- 
 bellum is laminated, and these laminae are striated ; each lamella contains two leaflets 
 of white substance covered with gray matter. The cerebellum is connected with the 
 medulla oblongata by the inferior peduncles, and with the brain by the superior pedun- 
 cles ; the middle peduncles and the transverse fibres pf the pons establish an intimate 
 connexion between the two lobes of the cerebellum, t 
 
 Development of the Cerebellum. 
 
 The cerebellum does not appear until some time after the spinal cord : it consists, at 
 first, of two laminae and plates prolonged from the cord, which approach each other to- 
 wards the median line ; these are the inferior peduncles of the cerebellum, or the resti- 
 form bodies. The human cerebellum in this condition has a close resemblance to the 
 same organ in fishes and reptiles. At the fourth month, the cerebellum forms a sort of 
 uniform girdle, four lines in width, around the tubercula quadrigemina and the medulla 
 oblongata ; the pons Varolii is already visible ; there is a rudiment of the corpus denta- 
 tum, and the surface of the cerebellum is entirely devoid of fissures. At the fifth month 
 there are four transverse fissures : a vertical section of the cerebellum presents five 
 branches ; but there are as yet neither laminae nor lamellae, nor is there any distinction 
 between the middle and lateral parts. At the sixth month, the cerebellum is divided by 
 the posterior notch, the different orders of fissures are visible, and the corpus dentatum 
 has acquired considerable size. During the last three months of intra-uterine existence, 
 the lateral lobes generally acquire that predominance over the middle lobe which is found 
 to hold after birth. 
 
 As the development of the spinal cord precedes that of the cerebellum, and as the cer- 
 ebellum appears to be formed by a prolongation of the posterior fasciculi of the cord, 
 does it follow that that organ is a production or an expansion of the cord 1 Certainly 
 not ; all that we can conclude is, that they are developed in succession. 
 
 Reil and Tiefdemann have advanced the opinion that the cerebellum is secreted by the 
 pia mater, and that the gray matter is deposited the last ; but this is only an assertion 
 without demonstration. 
 
 The cortical substance is formed at the same time as the medullary, and neither of 
 them can be considered as the product of the other. 
 
 Comparative Anatomy of the Cerebellum. 
 
 In fishes the cerebellum is generally small, but in the ray and shark it is large, subdi- 
 vided into convolutions, and prolonged above the optic lobes in front, and above the lobe 
 of the eighth pair of nerves behind. In the silures, as Weber has observed, the cere- 
 bellum is relatively as large as the human cerebrum ; for it covers the posterior half of 
 the cerebral lobes, as the cerebrum in man covers the cerebellum. In all fishes the cer- 
 ebellum contains a considerable cavity. In some of Ihis class of animals it is subdivi- 
 ded into segments, laminae, and lamellae.J 
 
 Reptiles. — There is no cerebellum in the batrachia (as in the frog, toad) and ophidia 
 (serpents) ; most anatomists, however, admit its existence in a rudimentary state. It 
 is very small, and shaped like a roof, or vaulted, in the chelonians (tortoise) ; it is very 
 long in the saurians (lizard, crocodile). 
 
 Birds. — The cerebellum is very large, and represents an ellipsoid, having its long di- 
 ameter directed vertically. It is deeply and regularly traversed by horizontal fissures, 
 which are curved downward on the upper half, and upward on the lower half of the or- 
 
 ical ; for the pons Varolii, and the meilallary fibres of which it consists, are found in the foetus at the fourth 
 month, that is, at a period when there are no laminae nor lamells, nor even any leaflets covered with gray mat- 
 ter. Gall, therefore, assumes these converging- fibres to originate from parts which do not appear until after 
 those fibres themselves." The refutation of Tiedemami appears to me to be itself founded on an assumption, 
 for there is no proof that the gray matter is formed after the white. 
 
 " Osservazioni sul' Cerveletto, p. 187. In the shark, the cerebellum consists of a gray and a white layer 
 united together and folded a great number of times upon themselves. 
 
 t It is not yet ascertained whether the lateral halves of the cerebellum act upon the same or opposite sides of 
 the body ; some cases, in which atrophy of one hemisphere of the cerebrum coexisted with atrophy of the op 
 posite hemisphere of the cerebellum, would appear to show that the action of the latter is not crossed. The 
 laminated structure of the cerebellum and its twofold composition suggested to Rolando the idea of comparing 
 it to a voltaic pile, or electro-motive apparatus. 
 
 t [It is divided into segments by deep transverse furrows in some cartilaginous fwhe.^.1 
 
THE CEREBRUM. 725 
 
 gan. They all tenninate opposite two small tubercles or appendages, situated one at 
 each extremity of the transverse diameter. Upon a section of the cerebellum of birds 
 is seen an arbor vitae, composed of white substance covered with gray matter. 
 
 Mammalia. — In the three classes already examined, the cerebellum has merely a mid- 
 dle lobe : in all mammalia there are also lateral lobes. They are at lirst small, like ap- 
 pendages, as in the rodentia, in which the cerebellum differs but little from that of birds ; 
 they gradually increase in size as we proceed upward in the scale, until they reach their 
 highest state of perfection in man, the development of whose cerebrum and cerebellum 
 exceeds that of the same parts in all the lower animals. In mammalia the size of the 
 lateral lobes of the cerebellum is directly proportioned to that of the oUvary bodies, the 
 existence of which in this class Vicq d'Azyr has erroneously denied. 
 
 THE CEREBRUM, OR BRAIN PROPER. 
 
 Definition — Situation — Size and Weight — General Form. — The Superior or Convex Surface. 
 — The Inferior Surface or Base — its Median Region, containing the Inter-peduncular Space, 
 the Corpora Albicantia, the Optic Tracts and Commissure, the Tuber Cinereum, Infundibu- 
 lum, and Pituitary Body, the Anterior Part of the Floor of the Third Ventricle, the reflected 
 Part of the Corpus Callosum, the Anterior Part of the Longitudinal Fissure, the Posterior 
 Part of the Longitudinal Fissure, the Posterior Extremity of the Corpus Callosum 'and Me- 
 dian Portion of the Transverse Fissure, and the Transverse Fissure. — The Lateral Regions, 
 including the Fissure of Sylvius and the Lobes of the Brain. — The Convolutions and Anfrac- 
 tuosities of the Brain, upon its Inner Surface, its Base, and its Convex Surface — Uses of the 
 Convolutions and Anfractuosities . — The Internal Structure of the Brain — Examination by 
 Sections — Horizontal Sections showing the Corpus Callosum, the Septum Lucidum, the For- 
 nix and Corpus Fimbriatum, the Velum Interpositum, the Middle or Third Ventricle, the 
 Aqueduct of Sylvius, the Pineal Gland, the Lateral Ventricles, their Superior and Inferior 
 Portions, the Choroid Plexus, and the Lining Membrane and the Fluid of the Ventricles — 
 Median Vertical Section — Transverse Vertical Sections — Section of Willis. — General Re- 
 marks on this Method of Examining the Brain. — Methods of Varolius, Vieussens, and 
 Gall. — Gall and Spurzheim's Views on the Structure of the Brain. — General Idea of the 
 Brain. — Development. — Comparative Anatomy. 
 
 The cerebrum or brain, strictly so called, is that portion of the encephalon which occu- 
 pies the whole of the cavity of the cranium, except the inferior occipital fossae. It forms, 
 as it were, the crown or summit of the spinal axis, surmounting it {cerebrum superius), 
 and, at the same time, lying in front of (cerebrum aiiterius) the spinal cord, as the origin 
 and termination of which it has been alternately regarded. By the pons Varolii and the 
 anterior or cerebral peduncles it is intimately connected with the cerebellum and the 
 spinal cord. The tentorium cerebelli completes the cavity in which it is enclosed, and 
 separates it from the cerebellum, wljich is situated below its posterior lobes. The cra- 
 oiiim, the dura mater, the arachnoid, and the pia mater form a fourfold investment for it. 
 
 Size and Weight of the Cerebrum. 
 
 The great size of the cerebrum is undoubtedly one of the most characteristic points in 
 the structure of man : in several animals, the entire encephalon is relatively as large, 
 and even larger {ex., the canary bird, the sapajou, the dolphin) ; but in reference to the 
 size of the brain properly so called, i. e., of the cerebral hemispheres, even the most fa- 
 voured animals are much inferior to man.* 
 
 In the adult, the weight of the cerebrum, detached from the cerebellum and the pons 
 by a section through its peduncles, varies from two to three pounds. t I believe it to be 
 impossible to construct a table of the comparative size and weight of the brain and of the 
 body. Is it not evident, indeed, that one element in the comparison, namely, the weight 
 of the body, is subject to great variety 1 Haller has recorded the results of all the cal- 
 culations which have been made upon this subject, and the diversity of those results is 
 the best comment that can be made upon this mode of comparison. 
 
 These remarks do not apply to the relative proportions between the cerebrum and 
 
 • The weight of the cerebrum of the horse and the oi is scarcely half that of the human cerebrum. 
 
 t [From the statements given by Tiedemanu (Htm des Negers, <fcc., p. 6, Heidelb., 1837), it appears that 
 the prevalent vreight of the brain (entire encephalon) in the adult male is about from 44 to 48 oz. troy : in the 
 adult female, from 40 to 44 oz. The results deducible from Dr. Sims's tables do not materially differ from 
 the above. 
 
 In thirty-nine males, varying in age from 22 to 80, Tiedemann found the minimum weight of the brain 38 oz. 
 20 gr., the maximum 59J oz. 
 
 In eleven females, from 20 to 80 years of age, the minimum was 32 oz. 5 drs. 50 grs., the maiimum 46 oz. 2 drs. 
 
 Th»eitremes, according to Dr. Sims's observations, were in about seventy males from 20 to 91 years, lowest, 
 33 oz. 80 grs. ; highest, 54 "oz. 6 drs., troy weight. In ninety females, between the ages of 20 and 89, the low- 
 est was 27 oz. 80 grs., the highest 51 oz. 6 drs.] 
 
726 NEUROLOGY. 
 
 cerebellum. According to my own observations, the weight of the cerebellum is from 
 the twelfth to the eighth part of that of the cerebrum.* 
 
 It is important to obtain some approximation to the relative size of the brain in differ- 
 ent individuals in the two sexes, and at different ages. 
 
 It results, from a great number of facts, that the size of the brain is independent of the 
 stature of the individual ; that the size of the brain is also independent of sex, although, 
 since the time of Aristotle, it has been the custom to repeat that the female brain is 
 smaller than that of the male ; that in the fcetus and the infant the cerebellum is rela- 
 tively much larger than the adult ; and that in old age the brain is often atrophied like 
 other organs, and then does not completely fill the cranial cavity. 
 
 Can the size of the brain be increased by exercise, and diminished by inaction 1 It 
 cannot be doubted that the brain must, in this respect, obey the laws which regulate all 
 other organs ; but the bony parietes of the cranium must offer great obstruction to its 
 development ; indeed, examples have been recorded of compression of the brain, and 
 even of death, produced by hypertrophy of this organ. 
 
 If it be true that the power of an organ depends upon its size, it follows that the size 
 of the brain, and, consequently, the capacity of the cranium, must have a tolerably close 
 ralation to the development of the cerebral functions ; but the activity of these functions 
 is connected with so many circumstances besides the size and quantity of brain, that 
 any estimate of the intellectual powers founded exclusively upon these data is very often 
 faulty and inexact, t 
 
 The Specific gravity of the brain, as compared with that of water, is, according to Mus- 
 chenbroek, as 1030 to 1000. It would be interesting to determine whether its specific 
 gravity varies according to age and in disease, and also whether it differs in different 
 animals. According to Soemmering, the specific gravity of the brain in old persons is 
 less than in those of middle age. 
 
 General Form of the Cei'ehrum, 
 
 The form of the cerebrum corresponds exactly to that of the cranial cavity, which is, 
 as it were, moulded on it ; it is, therefore, variable like that of the cavity itself, which, 
 during early infancy, is capable of assuming all sorts of shapes from the application of 
 external pressure. 
 
 If the entire cranial cavity, exceping the posterior occipital fossae, be filled with plas- 
 ter of Paris, an exact representation will be obtained of the general form of the brain 
 which had been removed. The cerebrum, therefore, is like the cranium of an ovoid fig- 
 ure, having its large end turned backward, and its small one forward. It is divided on 
 its under surface into lohes, which occupy the different compartments in the base of the 
 cranium. The entire surface is marked by deep tortuous furrows (see Jigs. 276, 282), 
 called anfractuosities, which occasion an appearance like that of the convolutions of the 
 small intestines, and hence the term convolutions is applied to the eminences resembling 
 folds, by which the anfractuosities are bounded. 
 
 The Superior or Convex Surface of the Brain. 
 
 A median vertical fissure running from before backward, called the longitudinal fi^ssure, 
 divides the cerebrum into two exactly similar lateral halves, which are improperly called 
 cerebral hemispheres, for each of them resembles the fourth part of an ovoid ; but would 
 be more correctly designated the right and left brain, as was done by Galen.j The lon- 
 gitudinal fissure divides the cerebrum in its whole depth, both in front and behind (x y, 
 fig. 277 ; also fig. 282) ; but in the middle it is interrupted by the corpus callosum {d d). 
 There are two brains, as there are two spinal cords and two cerebella.^ 
 
 The cerebrum is therefore symmetrical, but it is less completely so than the spinal cord ; 
 I should even say that a decided disproportion is very commonly observed between the 
 right and left hemispheres. It does not appear that this want of symmetry exerts that 
 influence upon the intellectual faculties which was imagined by the ingenious Bichat, 
 whose own unsymmetrical brain was in direct contradiction to his doctrine. It is, nev- 
 ertheless, possible that a want of symmetry, when carried to a certain point, may affect 
 the intellect ; in the brains of several idiots, their want of symmetry has been very re- 
 
 * In three young subjects I found as follows : 
 
 
 lb. 
 
 oz. 
 
 
 oz 
 
 Cerebrum . 
 
 . . 2 
 
 2 
 
 Cerebellum . 
 
 • ^ 
 
 it 
 
 . . 2 
 
 8k 
 
 " 
 
 . 3J 
 
 " . . 
 
 . . 2 
 
 5 
 
 " 
 
 . 5 
 
 + Persons endowed with strong memories have always appeared to me to have large brains ; and the part 
 which the memory performs in the exercise of mind is of such a nature that we cannot be surprised if the persons 
 alluded to are frequently men of superior intellect. I have known many persons, having heads of considera- 
 ble size, who had merely a good memory, but none of the characteristics of genius. Those in whom tlie braiu 
 is large seem to me to resist the power of disease better than sucli as have small brains. 
 
 } Chaussier applies the terra lobe to the hemispheres, reserving that of lobule for the secondary divisions. 
 
 <) Galen inquires why there should be two brains ; and replies, that it is to ensure a more perfect p^form- 
 *nce of the cerebral functions. I have seen several hemiplegic individuals in whom the whole of one hemi- 
 sphere was atrophied, but who, notwithstanding, possessed ordinary intellectual faculties. 
 
THE BASE OF THE BRAIN. 
 
 727 
 
 markable. I have seen the longitudinal fissure of the brain deviate to the right or left 
 Bide at an angle of from 15° to 20° degrees from its usual direction. 
 
 Each cerebral hemisphere presents three surfaces for our consideration : 
 
 An internal surface {fig. 282), which is flat, vertical, and separated from that of the 
 opposite hemisphere by the falx cerebri ; but as the falx does not extend so low as the 
 corpus callosum, it follows that the two hemispheres are in contact below, the pia mater, 
 however, intervening between them. In those rare cases of absence of the falx cerebri, 
 the corresponding faces of the two hemispheres are in contact with each other through 
 out their whole extent. I have seen one case in which the falx was imperfect, and the 
 two hemispheres were united. 
 
 An external surface, which is convex, and resembles the surface of the fourth part ot 
 an ovoid, having its great end directed backward ; it corresponds to the concavity formed 
 by the frontal, parietal, and occipital bones. 
 
 An inferior surface, which forms part of the base of the brain in general, and will be 
 next described. 
 
 The Inferior Surface or the Base of the Brain. 
 
 The hase of the brain {fig. 276), admirably described and correctly figured bv Soemmer- 
 ing in a special treatise upon the p^^^ 276. 
 subject,* presents a great number 
 of objects for our consideration. In 
 order to obtain a perfect knowledge 
 of it, it is advisable to examine it 
 while the brain is still enclosed in 
 its membranes, and placed in the 
 scull-cap, with its base uppermost ; 
 and also upon a brain from which 
 the membranes have been remo- 
 ved, and which is placed in the 
 same position, but on a flat surface. 
 In the former case, the parts form- 
 ing the base of the brain are press- 
 ed together, and may be studied as 
 a whole ; and in the latter, they are 
 separated, and may be examined in 
 detail. 
 
 It is at its base that the brain i 
 connected with the other parts o 
 the cerebro-spinal axis by means 
 of the right and left peduncles {ff), 
 which may be regarded as the roots 
 of the two hemispheres. 
 
 The Median Region. — In the me- 
 dian line, opposite the centre of 
 the base of the brain, and in front 
 of the pons Varolii (d), is situated 
 an excavation, which may be called 
 the median excavation of the base of 
 the brain. This excavation has already been alluded to in the description of the arach- 
 noid membrane and the sub-arachnoid fluid, with which this excavation is filled : it is 
 formed by the brain being curved upon itself, and is partially effaced when that organ 
 is placed with its base uppermost upon a flat surface : this excavation is of a pyram- 
 idal form, the apex being directed upward and the base downward. The borders of 
 the excavation form a hexagon, and contain the arterial hexagon of the base of the cra- 
 nium, named the circle of Willis. The posterior borders of the hexagon are formed by 
 the peduncles of the brain, the lateral borders by the inner part of the posterior lobes [c, 
 middle lobest] of the cerebrum, and the anterior borders by the inner and back part of 
 the anterior lobes {a) of the cerebrum. 
 
 From the six angles of this hexagon, six furrows proceed in different directions : from 
 the anterior angle, the fissure which separates the anterior lobes, or the great longitudi- 
 nal fissure {x) of the brain ; from the two anterior lateral angles, the corresponding fis- 
 sures of Sylvius (y y) ; from the posterior lateral angles, the two extremities (external to 
 //) of the great cerebral fissure, or great transverse fissure of the brain ; and from the pos- 
 terior angle (r), which corresponds to the interval between the cerebral peduncles, the 
 longitudinal groove {d) upon the pons Varolii. 
 
 * Do basi Encephali (Luduiig, Scriptores Neurologici, t. ii.). 
 
 + /. e., of the middle lobes of anatomists generally {c,fig. 276), which, it must be remembered, the author, 
 agreeing with Soimraering, does not regard as distinct from the posterior lobes (b), and to which, therefore, 
 he does not apply the term " middle lobes." This term is, however, for the most part added [between brack- 
 et*] in the translation, as it is generally used in anatomical descriptions in this country. 1 
 
728 NEUROLOGY. 
 
 In the area of this median excavation are seen the inter-pcduncular space (above r), the 
 mammillary tubercles {z, corpora matnmillaria vel albicaniia), the oplic tracts («) and optic 
 commissure (t), the posterior part of the floor of the third ventricle, or the tuber cinereum {v), 
 the infundibulum (i), and the pituitary body* 
 
 In front of the median excavation are situated, counting from behind forward, the an- 
 terior part of the floor of the third ventricle {lamina cinerea, m,fig. 282), the under or reflect- 
 ed portion of the corpus callosum (e), and the inferior part of the longitudinal fissure of the 
 cerebrum (x, flg. 276). 
 
 Behind the median excavation is the pons Varolii, and, behind that, the middle part 
 (r, fig. 282) of the great transverse fissure, by which the pia mater enters (above p) the 
 third ventricle, the thick posterior extremity (/) of the corpus callosum, and the posterior 
 part of the longitudinal fissure of the cerebrum. 
 
 The Lateral Regions of the Base of the Brain. — Upon each of these regions are seen the 
 inferior surface of the corresponding anterior lobe (a) of the cerebrum, the fissure of Sylvius 
 (y), by which this lobe is separated from the posterior lobe [middle lobe of others, c], and 
 the inferior surface of the posterior lobe itself (c b). There is no distinct middle lobe.t 
 
 I shall now describe, successively and in detail, the several parts just enumerated, 
 with the exception of the cerebral peduncles and the pons Varolii, which have already 
 been noticed as constituent parts of the isthmus of the encephalon. 
 
 The Median Region of the Base of the Brain. 
 The Inter-peduncular Space. 
 This space (above r) is of a gray colour, it is perforated by numerous openings for the 
 transmission of vessels, and is termed the middle or posterior perforated spot {locus per- 
 foratus) ; it contains the origin of the third pair of nerves (3). A longitudinal groove 
 and two fasciculi, separated from the corresponding cerebral peduncle by a blackish line, 
 are seen in this spot. These inter-peduncular fasciculi are forrhed by a prolongation of 
 the fasciculi of re-enforcement {faisceaux innomines) of the medulla oblongata. 
 
 The Corpora Albicantia. 
 
 The mammillary tubercles {corpora albicantia vel mammillaria, z) are two small pisiform, 
 or, rather, hemispherical globules, composed externally of white, and internally of gray 
 substance, situated behind the tuber cinereum, which is accurately adapted to their an- 
 terior surface, also behind the infundibulum, and between the peduncles of the brain. 
 They are separated from each other by a deep fissure, excepting at their highest part, 
 where they are connected by means of a thin layer of gray matter, which is very easily 
 torn ; they correspond {z, fig. 282) to the floor of the third ventricle (/). 
 
 It will be hereafter seen that the white cov.ering of these small bodies is formed by the 
 termination of the anterior pillars of the fornix, and hence the name given them by Cas- 
 serius, the bulbs of the anterior pillars of the fornix {bulbi priorum crurum fornicis), a 
 name which should be preserved. The two corpora albicantia are generally of equal 
 size. In several cases of atrophy of one of the hemispheres of the cerebrum, I have 
 found the corresponding mammillary tubercles also atrophied. 
 
 We are completely ignorant of the function of these bodies. 
 
 In man and the carnivora only are there two mammillary tubercles, and in all the oth- 
 er vertebrata there is but one. They attain their highest state of development in fishes, 
 if, as stated by Vicq d'Azyr, they are represented by the two larger lobes, which occupy 
 a corresponding situation in that class of animals. During the early periods of foetal 
 life they are blended together into one tolerably large mass, and do not become distinct 
 from each other until about the seventh month. 
 
 The Optic Tracts and Comm,issure. 
 At the point where the peduncles of the cerebrum pass into the brain, each of them is 
 surrounded by a white band, named the optic trad, or tract of the optic nerve. Each of 
 those tracts commences, behind, at an eminence called the corpus geniculatum externum 
 {JifiS- 271), which will be seen, hereafter, to be an appendage of that part of the brain 
 named the optic thalamus. The corpus geniculatum internum {i,figs. 271, 272) of au- 
 thors is merely a tubercle inserted into the bend or knee formed by the corpus genicula- 
 tum externum. The optic tract (2, fig. 272), then, is the continuation of the corpus ge- 
 niculatum externum, from which it is distinguished by its whiteness, which contrasts 
 strongly with the gray colour of that body : it is at first broad, flattened, and thin, and 
 is applied to the corresponding cerebral peduncle, being distinguished from the peduncle 
 only by the direction of its fibres. It then turns horizontally around the peduncle, is de- 
 tached from it, and at the same time becomes narrower and thicker ; having reached 
 the front of the peduncle, it changes its direction, passes forward and inward {s,fig. 276), 
 and is united with its fellow of the opposite side, to form the commissure or chiasma {t) 
 of the optic nerves (2). The optic tracts may be regarded as forming a commissure to 
 the two optic thalami. 
 
 * [To avoid confusion in the drawinfr, the pituitary body is not represented mfig. 276 ; its point of attncb 
 meut is to the infundibulum (i).] + See note, p. "27. 
 
THE BASE OF THE BRAIN. 729 
 
 These tracts and the cerebral peduncles of the two sides enclose a lozenge-shaped in- 
 terval, in which are situated the posterior perforated spot, the corpora albicantia, the tu- 
 ber cinereum, the infundibulum, and the pituitary body. 
 
 The Tuber Cinereum, the Infundibulum, and the Pituitary Body. 
 
 The terra tuber cinereum (») has been apphed by Soemmering to the soft gray mass 
 which occupies the triangular interval between the corpora albicantia and the optic 
 tracts. It is also called the floor of the third ventricle, because it closes that cavity be- 
 hind and below, and the base of the infundibulum, because that part is attached to it. 
 
 The infundibulum (la tige pituitaire, Lieutaud; la tige sus-sphenoidale, Chauss.) is a 
 reddish process (i), about two lines in length, directed very obliquely downward and for- 
 ward (i, fig. 282), and applied to the lower surface of the tuber cinereum : it is broad at 
 its upper extremity, but soon diminishes in diameter, and descends, to be inserted into, 
 and become continuous with, the pituitary body. 
 
 Is the infundibulum hollow, or is it a solid stem 1 The term infundibulum, or funnel, 
 applied to this part by the older anatomists, and the following synonymes, pelvis colatoria, 
 scyphus, aquce ductus, encephali sentina, afford ample evidence of both their anatomical 
 and physiological views regarding it. Galen and Vesalius, who are so often at variance, 
 are perfectly agreed upon this subject, and describe the infundibulum with a minute ex- 
 actness ; but since the communication supposed by Galen to exist between the nasal 
 fossae and the brain by means of passages through the ethmoid and sphenoid bones, and 
 the equally hypothetical communication admitted by Vesalius, are known to have no ex- 
 istence, anatomists have rejected the notion of the passage of a fluid from the brain in 
 this direction, and they no longer regard the infundibulum as a funnel intended for its 
 transmission. Haller has collected, in some learned notes, the contradictory opinions 
 of his predecessors, but has left the question still in doubt. Nor has Soemmering him- 
 self, after a long detail of investigation into the subject, arrived at a more satisfactory 
 result.* 
 
 A careful examination of the infundibulum has convinced me that there is, at least in 
 a certain number of cases, a funnel-shaped canal, precisely similar to that which was 
 described and figured by Vesalius : it is wide above, where it communicates with the 
 third ventricle, and narrow below, where it reaches the pituitary body, a body which the 
 ancients had not named, but which Vesalius called glan^ pituitam excipiens. In order to 
 demonstrate this canal, the optic tract must be turned backward, and the semi-transpa- 
 rent corneous lamina, which forms the anterior part of the floor of the third ventricle, 
 must be divided ; behind a white band, which is quite distinct from the anterior com- 
 missure of the brain, there is then seen a circular opening sufficiently wide to admit the 
 blunt end of a large probe, which may accordingly be passed through the entire length 
 of the infundibulum as far as the pituitary body. Again : by cutting the infundibulum 
 across, and then blowing upon it through a blowpipe, or letting some drops of water 
 fall upon it, a perfectly circular opening may be demonstrated, which cannot be produced 
 by the means employed in the demonstration. 
 
 Lastly, we may adopt the method of Vesalius, who filled the third ventricle with a 
 coloured liquid, which soon reached the pituitary body. The same experiment succeeds 
 still better with mercury. Nevertheless, I ought to state, that in two cases of dropsy 
 of the third ventricle, no fluid escaped from the infundibulum when it was cut across. 
 
 It is easy to show the structure of the infundibulum. A fibrous and vascular mem- 
 brane, continuous with the pia mater, forms its external covering, and this is lined by 
 a thin layer of gray matter, which is continuous with that of the floor of the third ven- 
 tricle. This gray matter forms a solid cord when the infundibulum is not tubular. 
 
 The pituitary bodyi is a small body, weighing from five to ten grains, which occupies 
 the sella turcica, or supra-sphenoidal fossa (appendice sus-sphenoidale du cerveau, 
 Chauss. ; hypophysis. Seem.). The better to appreciate its size, it is convenient to 
 break down, with a chisel, the quadrilateral plate which forms the posterior wall of the 
 sella turcica or pituitary fossa, and which is itself hollowed in front, so as to increase the 
 antero-posterior diameter of that cavity. J 
 
 Enclosed in the sella turcica, the pituitary body is kept in that situation on each side 
 by the fold of the dura mater, which constitutes the cavernous sinus, and above by a 
 portion of the same membrane, which forms a circular orifice around tlie infundibulum. 
 
 The coronary sinus, which is situated between the pituitary body and the margin of 
 the sella turcica in front and behind, and the cavernous sinuses on each side, form a 
 vascular circle around this body, but it is not bathed in the blood, as stated by some. 
 
 * Ludwig-, Script. Neurolog. ; Soemmering, De basi Encephali, p. 41. " Quibus omnibus absque partiwa 
 studio rite mecum perpensis, non potui non complecti illorura virorum sententiam, qui infundibulum, si non 
 perfecte solidum, certe non adeo conspicuo, uti veteres opinati sunt, canali perforatum esse, censuerunt." 
 Hunter and Cruickshank say that the infundibulum is sometimes solid, and sometimes tubular. 
 
 t Not shown in figs. 276, 282. 
 
 t In order to obtain a perfect examination of the pituitary body and infundibulum, it is well to sacrifice a 
 brain and the base of the cranium, and to remove, by a circular incision, the body of the sphenoid bone, to- 
 gether with the corresponding part of the base of the brain. 
 
 4Z 
 
7^ NEUROLOGT? 
 
 The upper surface of the pituitary body is slightly excavated, still it is not unfrequent- 
 ly convex, so as to project more or less above the level of its fossa. 
 
 On removing the pituitary body, it is seen to be formed of two distinct lobes, of which 
 the anterior is the larger, while the posterior occupies the small cavity in the quadrilat- 
 eral plate. These two lobes have been very well described by the brothers Wenzel ; 
 they are not of the same colour, the posterior lobe being grayish white, like the gray 
 substance of the brain, and the anterior yellowish gi-ay. 
 
 If the anterior lobe be pressed between the fingers, a yellowish-white pulp escapes 
 from it, very nearly resembling mixed plaster of Paris. An antero-posterior section of 
 the pituitary body shows, also, that the two lobes are perfectly distinct, being separated 
 by a fibrous layer. They are provided with a great number of small vessels. It has 
 been stated, but not proved, that the infundibulum contains two canals, one for the an- 
 terior, and the other for the posterior lobe. It is extremely rare to find any hard con- 
 cretions in the pituitary body like those met with in the pineal gland. 
 
 It is, perhaps, not uninteresting to remark, that the pituitary body is most highly de- 
 veloped in fishes, in which animals it forms a true lobe ; and that it is proportionally 
 more developed in mammalia, birds, and reptiles, than in the human subject. It is hol- 
 low in all the lower animals. 
 
 It is larger at the fourth, fifth, and sixth months of foetal life than after birth, and con- 
 tains a cavity which communicates with the third or middle ventricle. I pnce found a 
 considerable cavity in the pituitary body of an adult. 
 
 The functions of the pituitary body are enveloped in the greatest obscurity. Its con- 
 stancy in all vertebrated animals and its great vascularity are sufficient evidence of its 
 importance. It certainly conamunicates with the third ventricle, but for what purpose % 
 Does it pour a peculiar fluid into that cavity, or does it absorb a portion of the ventricu- 
 lar fluid 1 Whatever may be the use of the communication just alluded to, the pituitary 
 body does not communicate directly with the venous sinuses around it : it is not a lym- 
 phatic gland, as maintained by Monro ; nor is it a nervous ganglion of the great sympa- 
 thetic, as some have recently conjectured, because they fancied they saw some very fine 
 nervous filaments anastomosing upon it. The branches of the fifth and sixth nerves, 
 which Litre and Lieutaud say they have seen penetrating this body, have not been de- 
 monstrated. 
 
 The Anterior Part of the Floor of the Third Ventricle. 
 
 The anterior part {m, Jig. 282) of the floor of the third ventricle, which cannot be well 
 seen until the commissure of the optic nerves is turned backward, forms an inclined 
 plane directed downward and backward. It consists of a fibrous layer, which is contin- 
 uous with the neurilemma of the optic nerves ; and of a very thin, semi-transparent, but 
 very strong corneous layer {lamina cimrea), from which prolongations are given off to 
 the upper surface of the optic commissure, and continued upon the optic nerves : these 
 prolongations might be called the gray roots of the optic nerves. On dividing this horny 
 layer, the third ventricle (I) is laid open ; and it is seen that this layer forms a part of 
 the general system of gray substance, which, on the one hand, is prolonged upon the lat- 
 eral wall of the third ventricle, and surrounds the anterior pillars of the fornix, and, on 
 the other, is continuous with the tuber cinereum, above the optic commissure. 
 
 The Reflected Portion of the Corpus Callosum. 
 
 In front of the anterior part of the floor of the third ventricle is a transverse white 
 mass, which is nothing more than the fore part (e to m) of the reflected corpus callosum. 
 Terminating at this cross tract are two white fasciculi, which commence on each side 
 at the point where the corresponding fissure of Sylvius meets the great transverse fis- 
 sure of the brain ; they then pass inward and forward, along the outside of the optic 
 tracts, form the lateral boundaries of the anterior part of the floor of the third ventricle, 
 and terminate by becoming applied to, but not blended with each other, behind the re- 
 flected portion of the corpus callosum. Vicq d'Azyr has described these bands as the 
 veduncles of the corpus callosum. 
 
 The Anterior and Inferior Part of the Longitudinal Fissure. 
 
 This (x, fig. 276) is situated in front of the reflected })ortion of the corpus callosum, 
 and can only be seen in its entire extent after the removal of a very dense fibrous layer 
 which connects, sometimes very firmly, the back part of the right and left anterior lobes 
 of the cerebrum. Not unfrequently one of these lobes is seen to encroach upon the oth- 
 er : the falx cerebri, which is very narrow in front, occupies only a very small portion 
 of this fissure. 
 
 All the parts belonging to the median region of the base of the brain, which we have 
 hitherto described, are situated in front of the pons Varolii ; those which remain to be 
 examined are placed behind it : they are, counting from behind forward, the back part of 
 the longitudinal fissure, the posterior extremity of the corpus callosum, and the great horizontal 
 or transverse fissure. 
 
THE BASE OF THE BRAIN. 781 
 
 The Back Part of the Longitudinal Fissure. 
 This is bounded in front by the posterior extremity of the corpus callosum (/) ; and as 
 that extremity is at a greater distance from the back of the cerebrum than the anterior 
 extremity of the corpus callosum is from the front of the brain, it follows that the back 
 part of the longitudinal fissure is of much greater extent than the fore part (see Jigs. 277, 
 282). Moreover, this part of the fissure is free throughout its whole extent, for it is en- 
 tirely occupied by the base of the falx cerebri, while the fore part is only partially filled 
 with the apex of the falx : it might even be said that the posterior lobes have a tenden- 
 cy to separate from each other in this situation. 
 
 The Posterior Extremity of the Corpus Callosum, and Middle Portion of the Great Trans- 
 verse Fissure. 
 
 The posterior extremity {f,flg. 282) of the corpus callosum is named the bourrelet,* in 
 consequence of its being so much enlarged. This enlarged extremity, which we shall 
 afterward find is continuous with the posterior pillars of the fornix, constitutes the up- 
 per border of a fissure (r), the lower border of which is formed by the tubercula quadri- 
 gemina {f g). The pia mater (r to near k) enters at this median fissure, and forms the 
 velum interpositum, or tela choroidea : in this situation, also, is found the conarium or pi- 
 neal gland ; and it is here that Bichat described the orifice of his arachnoid canal. This 
 median fissure becomes continuous with a lateral fissure on each side, so as to form the 
 great transverse cerebral fissure. 
 
 The Great Transverse Cerebral Fissure. 
 
 The great cerebral fissure {Bichat), or the great transverse or horizontal fissure, follows a 
 semicircular direction, having its concavity directed forward ; it commences at the fis- 
 sure of Sylvius on one side {h,fig. 276 ; above 2, fig. 282), turns round the opposite cere- 
 bral peduncle, and ends at the opposite Sylvian fissure. 
 
 The peduncle of the cerebrum and the optic thalamus may be regarded as forming the 
 root of each cerebral hemisphere. Now the lateral part of the great transverse fissure 
 passes round the posterior half of this root, because it is in this situation that the cor- 
 responding cerebral hemisphere is turned inward upon itself It is this reflected and 
 concave surface of the hemisphere that forms the outer border of the corresponding lat- 
 eral portion of the transverse fissure, while the optic thalamus forms its inner border. 
 This fissure communicates directly with the inferior cornua of the lateral ventricles, and 
 through it the pia mater enters those ventricles, to form the internal pia mater of the brain. 
 
 The Lateral Regions of the Base of the Cerebrum. 
 The base of the cerebrum is divided on each side into two lobes, an anterior and a 
 posterior, separated by the fissure of Sylvius, j 
 
 The Fissure of Sylvius. 
 
 This is a fissure of considerable size (grande scissure interlobulaire, Chauss.), which 
 commences at the corresponding anterior extremity of the great transverse fissure, with 
 which it forms an obtuse angle. At the point where they meet is found a white sub- 
 stance,t perforated with large openings for bloodvessels ; this Vicq d'Azyr has named 
 the anterior perforated substance ; it is the locus perforatus anterior (h). 
 
 The fissure of Sylvius (y, fig. 276) is directed outward, and describes a slight curve, 
 having its convexity turned forward : it corresponds to the posterior border of the lesser 
 wings of the sphenoid bone, which are received into it. 
 
 The fissure of Sylvius cannot be properly examined until both the arachnoid and pia 
 mater have been removed. It is then found to be very deep ; it is seen that the middle 
 cerebral artery runs along the bottom of it, that the pia mater lines it throughout, and 
 that it soon divides into two branches, of which the anterior is the smaller, and contin- 
 ues in the original course of the fissure ; while the posterior, which is of much greater 
 extent, passes upward and backward, along the convex surface of the hemisphere, and 
 terminates after proceeding a variable distance ; the interval between these two second- 
 ary furrows is occupied by a sort of island (insula, Reil), which might be called the lobule 
 of the fissure of Sylvius, or the lobule of the corpus striatum. 
 
 This lobule is of a triangular form, having its base directed upward and its apex down- 
 ward ; it is marked by certain small superficial convolutions, which radiate from below 
 upward. It will be found immediately that this lobule corresponds to and is moulded 
 upon the corpus striatum, which is sometimes so large as to push the lobule beyond the 
 fissure, so that it reaches the surface of the brain, and appears to belong to the ante- 
 rior lobe. 
 
 The Anterior and Posterior Lobes of the Cerebrum. 
 
 Several anatomists describe three lobes in each hemisphere upon the base of the brain, 
 
 * Cushion, thick border. 
 
 t [Three, according to other anatomists: an anterior (a, Jig. 276), a middle (e), and a posterior (6) ; the 
 anterior separated from the middle by the fissure of Sylvius (y), the posterior resting- ou the cerebellum, or, 
 rather, on the tentorium.] " I CLight gray.] 
 
732 NEUKOLOGT. 
 
 namely, an anterior (a), a middle (c), and a posterior (i) ; but there are only two : an ante 
 rior (a), which rests upon the orbital plate of the frontal bone, is moulded upon its irregu- 
 larities, and is received into the concavity of that bone ; and a posterior (c b), which rests 
 upon the corresponding spheno-temporal fossa and the tentorium cerebelli. The an- 
 terior third of this posterior lobe, or the portion which corresponds to the spheno-tem- 
 poral fossa, is convex, and projects from six to nine lines below the level of the inferior 
 surface of the anterior lobe. The posterior two thirds are slightly concave ; they corre- 
 spond to the tentorium cerebelli, and are placed upon the same level as the anterior lobe. 
 The convex sphenoidal portion of the posterior lobe forms what is generally called the 
 middle lobe, and the posterior, or cerebellar portion, what is then named the posterior lobe. 
 I believe that it is useful, in many respects, to apply the terms frontal horn (cornu fron- 
 tale) to the anterior extremity of the cerebrum, which is received into the concavity of 
 the frontal bone, sphenoidal horn to the anterior extremity of the posterior lobe, and oc- 
 cipital horn to the posterior extremity of the same lobe. 
 
 The Convolutions and Anfractuosities of the Cerebrum. 
 
 The entire surface of the cerebrum is marked by a great number of deep, winding fur- 
 rows, which divide it into as many oblong eminences, turned in different directions, and 
 themselves subdivided by secondary furrows. These eminences have some resemblance 
 to the convolutions of the small intestine, and have been named, on this account, convo- 
 lutions, gyri, meandri, processus enteroidei. The furrows by which they are separated 
 are called anfracluosities or sulci. 
 
 A more accurate notion of the general character of these convolutions and anfractu- 
 osities may be obtained by supposing a bladder to be expanded round a compact central 
 mass, at a certain distance from it, and in this condition too large to be contained with- 
 in the cranium ; and then, that by means of threads proceeding from different points of 
 the centre, the corresponding parts of the bladder are drawn inward, so that it is folded 
 upon itself, and can now be contained within the cranial cavity. The various winding 
 folds and furrows produced in the walls of the bladder by drawing them from above and 
 from all sides towards the centre, will give some idea of the arrangement of the surface 
 of the cerebrum. 
 
 Some of the convolutions and anfractuosities are constant, because their forms are de- 
 termined by those of the central mass ; others are subject to variety, and seem to de- 
 pend upon no determinate cause : these varieties occur not only in different brains, but 
 also in the two hemispheres of the same brain. In this respect the human brain differs 
 from that of the lower animals, in which the cerebral convolutions present much less 
 variety, though they are not so constant as Vicq d'Azyr has stated. 
 
 The human brain is distinguished from the brains of the lower animals, not only by 
 its size and weight, but also by the number and size of its convolutions. Tiedemann 
 has given excellent representations of the progressive diminution of the cerebral convo- 
 lutions (which is accompanied by a diminution of the cerebellum) from the apes to the 
 rodentia and edentata.* In the human subject, as in the series of lower animals, the 
 development of the convolutions has always appeared to me to be directly proportioned 
 to the development of the entire brain. 
 
 In this point of view, as in many others, the human foetus presents a similar structure 
 to that found in the lower animals. The furrows or anfractuosities in the brain of the 
 human foetus at the fifth month are neither deeper nor more numerous than those in the 
 brain of the rabbit ; and it is important to study these primitive furrows, because they 
 correspond to certain anfractuosities which ultimately regulate the whole system of con- 
 volutions. Thus, at the fifth month, the great anfractuosity, which is called the fissure 
 of Sylvius, exists, but its borders are apart from each other ; the islantl of Reil, or the 
 lobule of the corpus striatum, is found upon the surface of the brain, and there is a lon- 
 gitudinal furrow at the lower and back part of the internal surface of each hemisphere , 
 it corresponds to the occipital prolongation or posterior cornu of the lateral ventricle ; 
 there is also a furrow above the corpus callosum ; and, lastly, the furrow of the olfactory 
 nerve is visible. At birth, all the convolutions exist, but they are not completely devel- 
 oped until about the age of six or seven years. 
 
 It is impossible to determine the number of the convolutions, for they have no appre- 
 ciable limits ; and although some of them end between two adjacent ones, it is easy to 
 see that this termination is merely apparent, and that near the point where it seems to 
 take place, the convolution is continued into another without any line of demarcation. 
 The ancient comparison, therefore, between the convolutions of the brain and those of 
 the intestines, not only applies to their direction, but also to their continuity. 
 
 There are several orders of convolutions. In fact, simple convolutions are seen to be 
 divided, excavated, and furrowed, more or less deeply ; but there are no regular and con 
 secutive subdivisions, as in the laminae of the cerebellum. Vertical sections made in 
 
 * [See also Leuret's figures in the work already referred to, in which will be found a comparative view of 
 the niunber and arrangen^nt of the convolutions of the bnun in man and mammalia.] 
 
CONVOLUTIONS AND ANPEACTD08ITIE3 OF THE BRAIN. 73S 
 
 different directions will show the arrangement of the convolutions much better than the 
 most careful observations of the external surface of the brain. 
 
 Each convolution presents to our notice two surfaces, a base or adherent border, and a 
 free border. The surfaces of the corresponding convolutions are moulded upon each 
 other, and separated by a duplicature of the pia mater. 
 
 The base or adherent border of each convolution is continuous with the central portion 
 of the hemisphere (see section, ^^. 277). 
 
 The free border is slightly rounded, so that between any two contiguous convolutions 
 there is a small groove, which is very distinct in cases of purulent infiltrations or depo- 
 sitions of lymph in the sub-arachnoid cellular tissue. 
 
 At the points where these convolutions meet, a triangular depression is observed. 
 These spaces are small in the natural state, but become very evident in cases of atrophy 
 of the convolutions. 
 
 The free border of some convolutions is frequently marked by an oblong depression or 
 groove, varying in depth and extent, and following the direction of the convolutions ; 
 these depressions are sometimes sharp, and radiate into three or four branches ; at other 
 times they are superficial, or, lastly, deep and narrow. The arteries and veins which 
 pass over the free borders of the convolutions form grooves upon them of various depths. 
 
 The free borders of most of the convolutions generally reach the surface of the brain ; 
 but besides the secondary convolutions, several of which remain concealed throughout 
 their whole length, between two adjacent convolutions, there are some principal convolu- 
 tions, which descend at one of their extremities between two adjacent convolutions ; and 
 there are others, again, which are depressed at one or at several points of their extent. 
 
 The depth of the convolutions varies from ten to fourteen lines, but it is extremely 
 variable in different individuals ; moreover, there are perhaps not two convolutions, nor 
 two parts of the same convolution, which correspond in thickness in the same brain ; 
 some are considerably swollen, while others are narrow ; there is almost always an en- 
 largement at the point where two convolutions become continuous. Eustachius and 
 Vieussens have erred, then, in representing all the convolutions as perfectly similar. 
 
 It would be undoubtedly curious to describe minutely all the convolutions. Vesalius, 
 who appears to have entertained the idea of so doing, likened the appearance of the sur- 
 face of the brain to those irregular forms which are traced by unskilful painters in de- 
 lineating clouds. Vicq d'Azyr made an unsuccessful attempt to elucidate this subject ; 
 Gall and Spurzheim, who were interested in giving a minute description of each convo- 
 lution, abandoned the task ; I have myself attempted, and so has Rolando, to describe 
 and name some of them. The description, however, to be understood, would require 
 the assistance of figures ; I shall, therefore, content myself with noticing, in this place, 
 the most important convolutions upon the internal surface, upon the inferior surface, and 
 upon the external surface, or convexity of each hemisphere. 
 
 Convolutions and Anfractuosities upon the Internal Surface. 
 
 The convolution of the corpus callosum is one which predominates over all those of the 
 internal surface of the hemisphere ; it is that which embraces the corpus callosum, and 
 hence its name. It commences in front, below the reflected extremity of that body, to 
 which it adheres, passes forward and upward, turns round its anterior extremity, then 
 extends backward, and having reached beneath the posterior extremity of the corpus 
 callosum, continues its course, and is arranged, in a manner to be presently described, 
 upon the lower surface of the cerebrum. 
 
 It is narrow at its anterior extremity, which Rolando regards as the principal root of 
 the olfactory nerve ; it increases in size as it proceeds, and opposite the middle of the 
 corpus callosum it is elevated like a crest, becomes much broader, and is marked by sev- 
 eral furrows, of which some are superficial and others deep. Tlie circumference of this 
 broad crest is divided into several branches, which become continuous either with the 
 superior convolutions of the convex surface, or with the posterior and superior convolu- 
 tions of the internal surface of the hemisphere. Vicq d'Azyr first pointed out this crest 
 of the convolution of the corpus callosum, and it was named by Rolando processo enter- 
 oido cristato. 
 
 The internal convolution of the anterior lobe is eccentric in reference to the one just de- 
 scribed, upon which it is moulded, a deep anfractuosity intervening between them. It is 
 very large at its origin in front of the fissure of Sylvius ; it forms the internal part of the 
 anterior lobe of the cerebrum, and having arrived in front of the crest of the convolution of 
 the corpus callosum, it passes upward, and becomes continuous with the convolutions 
 of the convex surface of the hemisphere. 
 
 This convolution is divided throughout its entire extent by a secondary anfractuosity, 
 which is at first straight, and then sinuous. 
 
 Convolutions and Anfractuosities of the Digital Cavity. 
 A very deep longitudinal furrow, which corresponds to the digital cavity of the lateral 
 ventricle, and, like it, constantly exists, extends from the convolution of the corpus cal- 
 
734 NEUROLOGY. 
 
 losum, near the posterior extremity of that body, directly backward along the posterior 
 lobe of the brain, which it divides into a superior and inferior portion. This anfractu- 
 osity of the digital cavity forms a division between the internal and inferior surfaces of the 
 hemisphere. 
 
 Ti\e convolutions of the digital cavity are the two longitudinal and tortuous convolu- 
 tions which bound this anfractuosity ; the upper convolution belongs to the internal sur- 
 face of the hemisphere, while the lower one forms part of the inferior surface. 
 
 Convolutions and Anfractuositics upon the Inferior Surface. 
 
 The great anfractuosity, called the fissure of Sylvius, divides the convolutions of the 
 inferior surface into those of the anterior and those of the middle and posterior lobe. 
 
 The convolutions of the anterior lobe constantly found are, the two small, straight, longi- 
 tudinal convolutions which bound the groove of the olfactory nerve {I, fig. 276), and the 
 flexuous convolution, which extends obUquely forward and outward, along the border of 
 the fissure of Sylvius, and is continuous behind with the external straight convolution 
 of the olfactory nerve. 
 
 The small convolutions and intervening anfractuosities are very irregular, and differ 
 in different individuals, and even on the two sides in the same individual ; into the de- 
 pressions formed between these convolutions are received the prominent ridges seen 
 upon the orbital plate of the frontal bone. 
 
 The Convolutions of the {Middle and) Posterior Lobe. — The convolution which runs along 
 the great transverse fissure is the continuation of the convolution of the corpus callosum, 
 and terminates in front by an unciform enlargement, which corresponds to the dilated 
 extremity of the comu Ammonis ; it forms the outer boundary of the great transverse 
 fissure. The convolution of the corpus callosum and its continuation, viz., that of the 
 transverse fissure, represent an ellipse, which is broken only at the fissure of Sylvius. 
 
 On the outer side of this convolution is a longitudinal anfractuosity, which corresponds 
 to the lower wall of the inferior comu of the lateral ventricle. 
 
 This anfractuosity is bounded by certain longitudinal convolutions, all of which pro- 
 ceed from the convolution of the transverse fissure, and are remarkable for their size 
 and windings. 
 
 The most internal of these convolutions forms the lower boundary of the anfractuosity 
 which I have said corresponds to the posterior comu of the lateral ventricle. 
 
 From the anterior part of the convolution of the transverse fissure some extremely 
 flexuous convolutions proceed from behind forward, assist in forming the sphenoidal 
 horn (point of the middle lobe), and become continuous with the convolutions of the ex- 
 ternal face of the hemisphere. 
 
 Convolutions and Anfractuosities of the Convex Surface. 
 
 The convolutions upon the convex surface of the hemisphere are, undoubtedly, the 
 most complicated ; on separating the borders of the fissure of Sylvius, within which the 
 island of Reil is contained, it is seen that the fissure is triangular, and presents three 
 sides : an inferior border, formed by the external convolution of the anterior lobe of the 
 cerebrum ; a posterior border, directed very obliquely upward and backward, which ap- 
 pears to receive all the occipital convolutions, and consists of a very tortuous convolu- 
 tion ; and a superior border, also consisting of a very winding convolution, in which the 
 majority of the superior convolutions terminate. 
 
 The convolutions upon the convex surface of the brain may be divided into the frontal, 
 the parietal, and the occipital. 
 
 The frontal convolutions are three or four in number, and are directed from before back- 
 ward. The parietal convolutions are three in number ; they pass in a serpentine direction 
 from within outward, and become continuous with the convolution which forms the su- 
 perior border of the fissure of Sylvius. The occipital convolutions are directed from before 
 backward, and proceed either from the posterior parietal convolution, or from the pos- 
 terior border of the fissure of Sylvius. 
 
 The occipital convolutions are the narrowest anil the most sinuous of all, so that the 
 sides of the sinuosities of each convolution are in mutual contact in the greatest part of 
 their extent, and touch the adjacent convolutions only at the points at which they are 
 bent.* 
 
 The frontal convolutions are also very flexuous, and have similar characters to the 
 occipital, but not so distinctly marked. They are larger than the occipital convolutions, 
 but smaller than the parietal, which are, moreover, less tortuous than either of the others. 
 
 The unusual details with which I have described the convolutions can only be justified 
 by the importance which has recently been attached to them. In the preceding descrip- 
 tion the following points have been noticed : Their general disposition, their windings, 
 and their mutual adaptation ; their continuity, and the impossibility of drawing any pre- 
 cise limits between them ; their general configuration, according to a common type, and 
 the want of uniformity in their details, not only in different brains, but also in the oppo- 
 
 * In senile atrophy, the occipital convolutions are chiefly affected. 
 
FUNCTIONS OF THE CONVOLUTIONS AND ANFEACTUOSITIES. 735 
 
 site hemispheres of the same brain ; their variable dimensions in different individuals, 
 both in respect of depth and width, these being always directly proportioned to the size 
 of the cerebral hemisphere : the individual differences both in the size of the brain and 
 in that of the convolutions are very great.* We have also seen that the internal surface 
 of the cranium is exactly moulded upon the surface of the brain, the digital impressions 
 in the cranial bones corresponding to the convolutions, and the ridges or eminences to 
 the small spaces intervening between the free borders of the convolutions. 
 
 Functions of the Convolutions and A nfractuositics. 
 ' The convolutions and anfractuosities render the surface of the brain of much greater 
 extent than it would otherwise have been. According to Vesalius, they are of use in 
 multiplying the surface, through which the bloodvessels carry nutritious matter into the 
 interior of the organ, t 
 
 The opinion that the anfractuosities and convolutions are intended to increase the 
 surface has been lately revived ; but the supposed object of this increase is very differ- 
 ent from that stated by Vesahus : thus, it has been agreed that, as there is an undoubt- 
 ed analogy between electrical phenomena and those manifested by the nervous system, 
 and as electrical phenomena are developed, not in proportion to the quantity of matter 
 concerned, but in proportion to the extent of surface, so the energy of the brain's action 
 may be in a direct ratio with the extent of its surface. In support of this opinion, the 
 phenomena of arachnitis are quoted, in which disease delirium more frequently occurs 
 than in inflammation of the cerebral substance itself Allusion is also made to the folds 
 observed in the retinae of birds, which greatly increase the intensity of vision : M. Des- 
 moulins, who is a principal supporter of this theory regarding the use of the convolu- 
 tions, states that he has observed these folds to disappear in birds which had been kept 
 in the dark, in the same way that the cerebral convolutions become atrophied, either 
 from the continued absence of all cerebral excitement, or from any other cause of intel- 
 lectual weakness. 
 
 The anatomists and philosophers of antiquity, considering that the convolutions were 
 more highly developed in man than in the lower animals, concluded that tlie intellectueil 
 superiority of the former was owing to this circumstance. Such was the opinion of 
 Erasistratus, facetiously refuted by Galen4 
 
 Gall and Spurzheim have recently revived this old opinion, and assuming, with some 
 philosophers, the existence of a plurality of mental functions, they have arrived at the 
 conclusion that there is also a plurality of material instruments or organs, by which 
 those functions are performed. These material organs are supposed by them to be the 
 convolutions, upon which they accordingly placed numbers corresponding to the differ- 
 ent mental faculties admitted by their philosophy : the difficulty was to settle on the 
 number of primitive mental faculties and their corresponding organs. According to Gall 
 and Spurzheim, the highest intellectual faculties of man are seated in the anterior lobes 
 of the cerebrum. 
 
 On the other hand, from an examination of the brains of fifty insane patients, M. Neu- 
 mann has been led to think that the occipital portion of the cerebrum is the seat of in- 
 telligence : this opinion derives some support from a fact which I have myself often ob- 
 served, viz., that atrophy of the brain of old persons in insanity affects the occipital 
 more than the frontal convolutions ; and also by the fact, that, as we descend in the ani- 
 mal series, the posterior part of the brain is observed to be the first to diminish, and 
 then entirely to disappear. 
 
 It is unfortunate for the system of Gall that the convolntions form a continuous whole, 
 and are not separated into distinct organs ; and it is also unfortunate that, upon the base 
 of the cerebrum, and upon the internzil surface of each hemisphere, there are convolu- 
 tions as distinctly marked as those upon the convex surface ; and yet, in the system of 
 Gall, the convolutions upon the base and internal surface of the hemispheres have been, 
 so to speak, disinherited ; for all the mental faculties have been located by him in the 
 convolutions of the convex surface. 
 
 The Internal Structure of the Cerebrum. 
 
 In order to make as complete an examination of the internal conformation of the brain 
 as is possible in the actual state of science, it should be prosecuted by means of sections 
 
 * Comparative anatomy fully confirms this fact : the convolutions of a small hemisphere are very sh'ghtly 
 developed, and they do not exist at all when the hemispheres are very thin, as in birds. 
 
 + The substance of the brain, says Vesalius, is not firm enough for the arteries and veins to traverse it with 
 impunity ; on the other hand, it is so thick that bloodvessels distributed over its surface would not have been 
 sufficient to nourish the entire mass ; and, therefore, nature has provided certain deep and winding furrows 
 upon the brain, into which the pia mater can penetrate, so as to convey to the deep-seated parts the materials 
 for their nutrition ; for the same Teason, the cerebellum has been divided into laminse and lamella. Vesalius 
 even states that the division of the cerebrum into two hemispheres is for no other purpose (lib. vii., cap. 4, 
 p. 542). 
 
 t " Quum asini etiam admodum multipliciter cerebrum habent complexnra quod deccret, quantum ad mo- 
 rum ruditatem attinet, omnifariam simplex et minime varium nancisi cwebrum." If this theory be true, says 
 Galeu, the ass ought to have a brain with a smooth surface, and no convolutions ; but it has numerous and 
 deep convolutions : the intellectual faculties, therefore, are independent of the convolutions. The conclusion 
 is not obviously contained in the premises. 
 
736 
 
 NEUROLOGY. 
 
 in different directions ; by tearing the brain, and by acting upon it with streams ol wa- 
 ter ; and liy dissecting brains that have been hardened by alcohol, or by being boiled in 
 oil or in a strong solution of salt. 
 
 Examination of the Internal Structure of the Brain by Sections. 
 
 This mode of examining the brain was the one employed by Galen ; it was revived by 
 Vicq d'Azyr, and is now generally adopted. 
 
 By means of these different sections it is easy to study the internal conformation of 
 the brain in its principal details. The other methods are more especially adapted for 
 determining the connexions of the several parts of the cerebrum with each other, or 
 with the other portions of the cerebro-spinal axis. I shall commence by an examina- 
 tion of horizontal sections of the brain.* 
 
 Horizontal Sections of the Brain. 
 On making an incision into the brain, this organ is found to consist of two substances . 
 a gray cineritious or cortical substance, and a ichite or medullary substance, which is sur- 
 rounded on all sides by the gray.t 
 
 First Section. — A horizontal section, made so as to remove the wpper half of the supe- 
 rior convolutions of the cerebrum, shows that each convolution consists of a central white 
 portion, surrounded on all sides with a layer of gray substance ; that the gray substance 
 is accurately moulded upon the white, the form of which determines that of the corre- 
 sponding convolution ; that the thickness of the gray matter varies from half a line to a 
 line and a half; and that it is far from being uniform, either in the same or in different 
 convolutions. In judging of the thickness, it is important to have regard to the direc- 
 tion of the section ; for it is easy to understand that an oblique section of the gray mat- 
 ter will give a very different result from one made perpendicularly. The section de- 
 scribed above also shows that the convolutions are continuous with each other, and it 
 enables us to comprehend their irregular, complex, and sinuous arrangement better than 
 could be done without cutting into the brain. 
 
 The relative proporiion of the gray and white substances in each convolution may be 
 determined approximately by macerating a brain for some days , the gray substance be- 
 ing softer and more readily decomposed, is thus converted into pulp, and may be easily 
 removed. The convolutions being thus reduced to the white substance only, appear 
 like short, white lamellas, arising from different points of the surface of the central me- 
 dullary mass. I estimate the gray matter at about five sixths of each convolution. 
 
 Second Section. — A horizontal section made beneath the base of the convolutions of the 
 convex surface of the hemispheres presents an appearance like that of a geographical 
 
 chart of a deeply and irregularly in- 
 dented coast ; an appearance which 
 cannot be described without fig- 
 ures. It consists of a central mass 
 of medullary substance, which is 
 narrowed like an isthmus behind: 
 extending from this central mass 
 are certain prolongations, which 
 may be divided into several orders, 
 and which are themselves subdivi- 
 ded, so as to form the medullary 
 centre of each convolution. 
 
 Third Section. — A horizontal sec- 
 tion, made on a level with, or, rath- 
 er, just above, the corpus callosum, 
 displays a great medullary centre in 
 each hemisphere (centre medullaire 
 hemispheral ; centrum ovale minus ; 
 acb, acb, Jig. 277). 
 
 The two centres of the opposite 
 sides, together with the corpus cal- 
 losum {d d), form the centrum ovale 
 of Vieussens. 
 
 The centrum ovale of Vieussens i« 
 contracted in the middle line, where 
 it is formed by the corpus callosum, 
 but is much larger in each hemi- 
 sphere. The anfractuosities by 
 which the circumference of this 
 section is indented are seen to be 
 deeper on the outside and behind, than on the inside and in front. 
 
 * The sections should be made with a very sharp instrument, a razor, for example. t See note, p. 701. 
 
THE CORPUS CALLOSUM. 737 
 
 By the three horizontal sections just described, it is shown that eacn convolution (/ f 
 f) consists of a white, central portion, surrounded by a thick layer of gray substance, 
 having a precisely similar shape ; that it is the gray matter which predominates in the 
 convolutions ; that the central portions of all the convolutions are continuous with each 
 other, and form the most complicated windings ; that they all rest upon a hemispherical 
 central mass, which becomes larger and larger towards the corpus callosum, on a level 
 with which it attains its greatest dimensions ; that the centrum ovale of Vieussens, 
 which, however, is not oval, represents the largest medullary surface of the brain, and 
 might be regarded as a centre, from which all the radiations that enter the convolutions 
 are given off in one direction, and, in the other, all those which establish connexions be- 
 tween the brain and the other parts of the cerebro-spinal axis ; lastly, that the centrum 
 ov£ile and the convolutions are always developed in a corresponding ratio. 
 
 The Corpus Callosum. 
 
 If, when the brain is resting upon its base, the two hemispheres be drawn asunder, a 
 transverse white band is seen at the bottom of the longitudinal fissure, extending from 
 one hemisphere to the other, and connecting them together, and forming their commis- 
 sure : this band is the corpus callosum* (mesolobe, Chaussier ; commissura cerebri mag- 
 na, maxima, Rcil, Soemmering, d d). On removing the upper part of the two hemi- 
 spheres by a horizontal section made about a line or two above the corpus callosum, it 
 is seen that each hemisphere encroaches upon the corpus callosum, and overhangs it 
 without adhering to it : the interval between the hemisphere and the corpus callosum 
 has been improperly termed the ventricle of the corpus callosum. But there is no cavity 
 here, nor is there a smooth exhalant and absorbing surface ; it is merely an anfractuos- 
 ity, separating the corpus callosum from the convolutions, and lined by the pia mater, 
 like all other anfractuosities. On continuing to remove successive portions of the hem- 
 isphere, it is found that it can be separated without any laceration from the corpus cal- 
 losum, much farther than the point at which the pia mater is reflected, and that the 
 hemisphere and corpus callosum are simply in- contact with each other ; the fibres of 
 the hemisphere are seen to be longitudinal, while those of the corpus callosum are 
 transverse. 
 
 From this observation, it follows that the middle or free portion of the corpus callo- 
 sum (shown in^^. 277) is but a small part of that body. 
 
 The corpus caUosum reaches much nearer to the anterior (x) than to the posterior (y) 
 extremity of the cerebrum, being an inch and some lines distant from the former, and 
 from two to three inches from the latter. 
 
 Its length is about three inches and a half; it is broader behind than in front ; its breadth 
 behind varies from eight to ten lines, if we include the part which is covered by the hem- 
 ispheres : its thickness, which can be properly shown only upon a vertical section (see 
 Jig. 282), along the middle line, is not uniform throughout ; its thickest part is at the 
 posterior extremity (/), which is about three lines thick : in front of this extremity it 
 diminishes abruptly, and is scarcely a line or a line and a half in thickness (d) ; it then 
 ^gradually increases from behind forward, and is about two lines thick at its anterior ex- 
 tremity, opposite the point of its reflection (c). 
 
 Inform the corpus callosum resembles an arch or vault, so that it would deserve the 
 *name of vault or fornix better than the»part usually so called. 
 
 Its vaulted form is distinctly shown upon a longitudinal vertical section {fig. 282), and 
 at the same time it is seen that the posterior extremity of the corpus callosum is rolled 
 up, as it were, so as to form an enlargement, while its anterior extremity is merely re- 
 flected downward and backward, and after its reflection becomes gradually thinner as it 
 descends, and terminates in a very delicate lamella. 
 
 The corpus callosum presents for our consideration a superior and an inferior surface 
 *and two extremities. The superior surface is convex, and, as it were, arched from be- 
 fore backward {medxdlaris arcus) ; it has no raphe along the median line, but presents in 
 that situation a slight groove (e, fig. 277), depending on the existence of two white Ion 
 gitudinal tracts, one on each side the middle line, which were regarded by Lancisi as 
 constituting a nerve, the longitudinal nerve of Lancisi. 
 
 These tracts are subject to variations : thus, they are sometimes slightly flexuous, 
 and contiguous to each other, and at other times they unite, and then separate. Duver- 
 ney has described certain ash-coloured longitudinal tracts, but their existence has been 
 denied by most anatomists. 
 
 The white longitudinal tracts are intersected at right angles by transverse fasciculi, 
 which constitute the corpus callosum. 
 
 The upper surface of the corpus callosum corresponds to the hemispheres on each 
 side ; it is free in the middle, where it corresponds to the arteries of the corpus callosum 
 and to the free margin of the falx, which has appeared to me to approach very closely to 
 
 * According to Ilaller, its name is derived from its whiteness, which has been compared to the colour of a 
 cicatrix ; according to others, it was given on account of the consistence of this part, which has been errone- 
 uslv regarded as exceeding that of other parts of the brain 
 
 5 A 
 
NEUROLOGY. 
 
 the posterior extremity of this body, but not to touch it, so that it could not occasion 
 any depression upon it. 
 
 The inferior surface of the corpus callosum is concave, and is free over a greater extent 
 than the superior ; it forms the upper wall or roof of the lateral ventricles (t i, fg. 278, 
 in which figure only the anterior and posterior extremities, e and d, of the corpus callo- 
 sum are left).* This surface is covered by the serous membrane of the ventricles, and, 
 hke the superior surface, it is fasciculated. 
 
 Along the median line it corresponds, in front, to the septum lucidum {t, figs. 278, 
 282), and behind to the fornix (k), with which it even seems to be united at this point. 
 In consequence of the somewhat regular arrangement of the fibres constituting the two 
 posterior pillars of the fornix (r r, figs. 278, 279), which diverge in this situation, and 
 also of that of the transverse fibres of the corpus callosum, the back part {s,fig. 279) of 
 the inferior surface of the corpus callosum has received the names of lyra, corpus psal- 
 loides, psalterium. 
 
 The posterior extremity of the corpus callosum (bourrelet, Reit), which, as we have al- 
 ready stated, is its thickest part, is slightly concave transversely, but presents no other 
 notch, excepting the median depression, between the longitudinal tracts. t 
 
 The anterior extremity of the corpus callosum does not terminate in an enlargement, like 
 the posterior, but it is reflected, and embraces the anterior extremity of the corpus stri- 
 atum : it then passes downward and backward (e, fig. 282), and terminates insensibly in 
 front of the anterior portion (m) of the floor of the third ventricle. Reil applies the term 
 knee (genu) to the point of reflection, and that of beak (rostrum) to the posterior and thin 
 extremity of the reflected portion. This reflected portion of the corpus callosum is seen 
 upon the base of the brain, between the anterior lobes : the convolution of the corpus 
 callosum also accompanies its reflected portion, and, instead of being merely in contact, 
 becomes continuous with it, so that the gray matter rests immediately upon the corpus 
 callosum. The longitudinal tracts arise from the reflected portion of the corpus callo- 
 sum ; and the inferior peduncles of the.corpus callosum (Vicq d'Azyr), already mention- 
 ed, terminate upon this portion. 
 
 The right and left borders of the corpus callosum enter deeply into the substance of 
 the hemispheres. 
 
 Beneath the corpus callosum are situated, in the median line, the septum lucidum (t t, 
 fig. 278), \h& fornix (k), the velum iyiterpositum (v,fig. 279), and the median or third ven- 
 tricle (c to x,fig. 280) ; and at the side, the lateral ventricles (i i,fig. 278). We shall pro- 
 ceed to examine these different parts in the above-mentioned order. To obtain a good 
 idea of their form and relations, it is important to study them upon two brains, one rest- 
 ing upon its convex surface, and the other upon its base. 
 
 The Septum Lucidum. 
 
 The septum lucidum, or transparent septum, so called because it separates the lateral 
 ventricles from each other and is semi-transparent, is situated in the median line (sep- 
 tum median, Chauss.). It is very well seen (t,fig. 282) when the corpus callosum has 
 been divided longitudinally on each side of the middle line. It appears like a thin lami- 
 na given off from the anterior and inferior part of the corpus callosum, and passing ver- 
 tically downward in front of the fornix ; it is of a triangular shape, broad in front and 
 narrow behind ; its lateral surfaces constitute the' internal walls of the lateral ventricles ; 
 its upper border is continuous with the corpus callosum, its posterior with the fornix, 
 and its inferior with the reflected portion of the corpus callosum in front, and with the 
 inferior peduncles of that body farther back. Hence Vicq d'Azyr imagined that the sep- 
 tum lucidum was a continuation of these peduncles. 
 
 The septum lucidum is composed of two very delicate and completely distinct lamel- 
 lae (t t, fig. 278), between which, in front, a cavity is enclosed, containing a few drops 
 of a serous fluid ; this small cavity is called the ventricle of the septum, the first ventricle 
 {Wenzel), the fifth ventricle (Cuvier), and the sinus of the median septum (Chauss.) ; it is 
 not very unfrequently the seat of dropsical effusion. I have found it filled with blood in 
 several subjects after death from apoplexy. 
 
 As to whether this ventricle of the septum communicates with the other ventricles, 
 opinions are divided. Tarin describes a small fissure opening between the anterior pil 
 lars of the fornix, but the majority of anatomists have not. been able to demonstrate it 
 It appears to me that the absence of all communication is a well-ascertained fact. 
 
 Each of these lamella; of the septum lucidum consists of a medullary layer, covered 
 on the outside by the membrane of the corresponding lateral ventricle, and on the inside 
 by the membrane of the fifth ventricle. The existence of this last-mentioned membrane 
 is proved by the smooth appearance of the ventricle, and it may be demonstrated by re- 
 
 * The best mode of examining the lower surface of the corpus callosum is to view it by opening the ventri- 
 cles from the base of the brain. 
 
 t One is astonished to read, in Chaussier's work, that the notch of the posterior extremity of the corpus 
 ■ callosum is caused by the alternate movements of elevation and depression of the brain. At each elevation, 
 according to him, this extremity of the corpus callosum strikes against the free margin of the falx cerebri al- 
 though that margin is at some slight distance from it. 
 
THE FORNIX AND CORPUS FIMBRIATUM. 
 
 739 
 
 Fig. 278. 
 
 moving, in succession, layers from the outer surface of the lamella. The gray matter of 
 the third ventricle is prolonged upon the external surface of each lamella of the septum 
 
 The Fornix and Corpus Fimbriatum. 
 
 The fornix (la voute a trois piliers, k, r r, fig. 278) is a medullary arch, situated (i, 
 fig. 282) beneath the corpus callosum, 
 with which it is continuous behind, 
 but which it leaves in front, and then 
 passes perpendicularly downward, de- 
 scribing a curve within the curvature 
 of the corpus callosum. The interval 
 between the anterior part of the fornix 
 and the corpus callosum is occupied 
 by the septum lucidum. To the term 
 fornix, used by the older writers, the 
 epithet a trois piliers has been improp- 
 erly added by Winslow, inasmuch as 
 it expresses a mere appearance ; for 
 there are in reality /owr pillars, the two 
 anteriQf of which are closely approxi- 
 mated to each other, while the two 
 posterior are widely apart. 
 
 The fornix resembles an isosceles 
 triangle {trigone cerebral), having the 
 anterior angle very much elongated 
 and soon bifurcated ; its posterior an- 
 gles suddenly diverge, pass downward 
 and outward, and are prolonged (r r) 
 into the inferior or reflected portions 
 or descending cornua of the lateral 
 ventricles, where they constitute Che 
 corpora fimbriata (s) ; or, rather, the 
 fornix may be said to be composed of 
 two perfectly distinct medullary cords, 
 which are applied closely to each other, become broader and flatter as they proceed 
 backward and downward, and separate from each other opposite the reflected portions 
 of the lateral ventricles, into which they enter. The fornix, therefore, resembles the 
 letter X placed horizontally, the anterior limbs of which are close to each other (be- 
 tween q q) and very short, while the posterior limbs (r r) are very long and widely apart. 
 The term fornix is really applicable only to that portion which is applied to the corpus 
 callosum. Reil, who has described and figured this part better than any of his prede- 
 cessors, not even excepting Vicq d'Azyr and Soemmering, calls the fornix the twain-band. 
 
 The superior surface of the fornix corresponds, in the median line, to the septum luci- 
 dum in front, and to the corpus callosum behind : on each side it is free, and forms a part 
 of the floor of the lateral ventricles. The choroid plexuses (jp p) are sometimes reflect 
 ed upon the surface of the fornix. 
 
 In order to understand the relations of the fornix with the corpus callosum, it is ne- 
 cessary to bear in mind that it is composed of two flat medullary bands. Now the inter- 
 nal contiguous borders of these bands are turned upward, and adhere to the lower sur- 
 face of the corpus callosum, so as to form a small vertical septum, which is continuous 
 with the back part of the septum lucidum. The medullary fibres of the septum lucidum 
 are therefore generally considered to be continuous with those of the fornix. 
 
 The inferior surface of the fornix (r r, fig. 279) rests upon the velum, interpositum {v), 
 which separates it from the third ventricle (c b x, fig. 280) and the optic thalami {I I), the 
 internal portion of which bodies is covered by the fornix (see^o'. 278). It is upon the 
 posterior portion of this inferior surface, where the two medullary bands of the fornix 
 separate from each other to enter the descending cornua of the lateral ventricles, that 
 we find that regular though variable arrangement of transverse fibres (s), abutting on 
 certain longitudinal fibres (r r), which has been named the lyra, corpus psalloides or psal- 
 terium. I have already noticed this structure, which was erroneously regarded by Gall 
 as composed of the uniting fibres of the fornix. 
 
 The edges of the fornix are thin and free, and are bordered by the choroid plexuses. 
 
 The anterior pillars of the fornix {k, figs. 279, 280), which Vieussens, Tarin, and others 
 described as arising almost indifferently either from the cerebral peduncles, or from the 
 anterior commissure (c, fig. 280, situated in the third ventricle), can only be well seen 
 in a longitudinal vertical section of the cerebrum made exactly in the median line. Each 
 half of the cei-ebrum will contain the corresponding band of the fornix ; and it will then 
 be seen, as was first described by Santorini, that each anterior pillar (seen below k and 
 behind c,fig. 282) arises from the corpus albicans (z) of its own side : hence these bodies 
 
740 NEUROLOGY. 
 
 have been called the bulbs of the fornix. The whole of the white covering of each of the 
 corpora albicantia (/, fig. 283) appears to be formed into a thick white fasciculus or cord, 
 which passes upward,- and may be very easily traced with the handle of the scalpel 
 through the soft gray matter which forms the inferior and anterior portion of the wall of 
 the third ventricle. While passing through this gray matter the cord describes a curve, 
 having its concavity turned backward, and is situated between the optic thalamus and 
 the corpus striatum, and behind the anterior commissure {c,fig. 282 ; m, fig. 283) ; having 
 emerged from the gray matter, which is still prolonged along its anterior surface and 
 thus reaches the septum lucidum {t), the anterior pillar is reflected backward {h, fig. 283) 
 in front of the optic thalamus, and becomes changed into a flat band {k,fig. 282), which 
 is applied to the thalamus (/), and follows the contour of that body : at the point where 
 the anterior pillar of the fornix changes from an ascending to a horizontal direction, it 
 forms half a ring (situated behind and below k,fig. 282), which is completed by the an- 
 terior part of the optic thalamus. This is the opening of the foramen of Monro, by which 
 a communication is established (opposite q q, fig. 278) between the third and the corre- 
 sponding lateral ventricles. 
 
 The Posterior Pillars. — Having arrived opposite the back part of the optic thalamus, 
 each of the lateral bands of the fornix, which had already been directed somewhat ob- 
 liquely outward, passes abruptly and very obliqely outward and downward (r r) into the 
 descending cornu (A) of the corresponding lateral ventricle, and is there divided y;ito two 
 parts, one of which forms the superficial medullary substance of the cornu ammonis, or 
 hippocampus major (m), while the other follows the concave border of the hippocampus, 
 and takes the name o{ corpus fimhriatum (s), corps frangi, corps borde. We shall again al- 
 lude to these parts in describing the lateral ventricle. 
 
 I have said that the anterior pillars arise from the corpora albicantia, but they have a 
 much deeper origin, which was figured by Vicq d'Azyr, and has been still better descri- 
 bed by Reil. According to that anatomist, they arise within the optic thalami. I have 
 traced them much farther than Reil, as far as the tcenia semicircularis on each side ; or, 
 rather, each tania semicircularis {n, fig. 278), which is situated in the lateral ventricle be- 
 tween the corpus striatum (i) and the optic thalamus {I), and which is continuous with 
 the anterior corpus quadrigeminum or natis of its own side, becomes subdivided into two 
 bands, which may be regarded as the roots of the corresponding anterior pillar of the for- 
 nix. Of these two roots, one is superficial (w), and easily seen without dissection ; the 
 other is deep-seated {v, fig. 283), enters into the substance of the optic thalamus, runs 
 forward to the corpus albicanus (/), spreads out and forms the surface of that body, and 
 then curves upward to constitute the anterior pillar of the fornix (A), at the point where 
 it emerges from the gray matter. 
 
 The two bands of the fornix also receive some other white fibres, which greatly mul- 
 tiply its connexions. Thus, as they are traversing the gray matter, the anterior pillars 
 receive additional medullary fibres, some arising from the gray matter itself, and others 
 from the commissure of the optic nerves ; again, just as they emerge from the gray mat- 
 ter to become horizontal, they receive a considerable cord, formed conjointly by the white 
 fibres covering the optic thalamus {g, fig. 283) by a white band, which runs longitudinal- 
 ly along the optic thalamus, and is continuous with the corresponding peduncle of the 
 pineal gland, and by the superficial fibres of the taenia semicircularis, of which I have al- 
 ready spoken. These three sets of fibres form a cord of considerable size, which is bent 
 abruptly backward, and becomes continuous with the fornix. Lastly, the fornix receives 
 or, perhaps, it gives origin to, the white radiated fibres of the septum lucidum. 
 
 Fig. 279. ffig Velum Interpositum. 
 
 Beneath the fornix is situated a vascu ar memorane, a pro- 
 longation of the external pia mater : this is the velum interposi- 
 tum, or tela choroidea (v, fig. 279), so named by Herophilus from 
 its tenuity, which he compared to that of the fcetal membrane 
 called the chorion. 
 
 It is thus formed : the external pia mater, having arrived be- 
 low the enlarged posterior extremity of the corpus callosum, 
 penetrates (at r,fig. 282) into the interior of the brain between 
 that body and the tubercula quadrigemina, and forms a sort of 
 triangular web {v, fig. 279), the base of which is turned back- 
 ward, and the truncated and bifurcated apex forward. The up- 
 per surface of the velum is covered by the fornix (reflected at 
 r r), to which it transmits a great number of vessels. Its infe- 
 rior surface forms the root of the third ventricle, and corresponds 
 on each side to the upper and to a small part of the inner sur- 
 face of the optic thalami (/ /). The velum is also in relation with 
 the venae Galeni and with the pineal gland {p, fig. 282), adhering 
 very closely to that body, and forming a nearly complete invest- 
 ment for it, so that they are almost always removed together 
 
THE MIDDLE OR THIRD VENTRICLE. 
 
 741 
 
 Sicfiat Sescribed his so-called arachnoid canal as passing beneath the velum interposi- 
 tum. Upon the lower surface of the velum, which can only be properly examined from 
 below, are found two small trains of red granulations, precisely similar to the choroid plex- 
 uses of the lateral ventricles, with which they are continuous in front : they may be call- 
 ed the choroid plexuses of the third ventricle. 
 
 The lateral borders of the velum are continuous with the upper part of the choroid plex- 
 uses {pp,figs. 278, 279) of the lateral ventricles. 
 
 The anterior extremity, or apex of the velum, is bifid ; each branch of the bifurcation 
 passes from the third into the corresponding lateral ventricle (behind k,Jig. 282, opposite 
 q q, Jig. 278), behind the anterior pillar of the fornix, and constitutes the anterior extrem- 
 ity of the choroid plexus. 
 
 The velum interpositum is formed by the pia mater, supported by a tolerably strong 
 fibrous layer. 
 
 When the fornix and the velum (as in Jig. 280) are removed, we arrive at a cavity call- 
 ed the middle or third ventricle. 
 
 The Middle or Third Ventricle. 
 Dissection. — In order to expose the third ventricle from the base of the brain, the right 
 
 Fig. 280. 
 
 peduncle of the cerebrum and the right 
 corpus albicans should be separated 
 from those of the left side by a longi- 
 tudinal section in the median line. 
 There is another section, which I rec- 
 ommend as exceedingly well adapted 
 to exhibit all the parts contained in the 
 third ventricle ; it is made from before 
 backward, and on either the right or 
 left side of the median line, so as to 
 leave both of the lateral walls of the 
 third ventricle uninjured. 
 
 The third ventricle (c to x, figs. 280, 
 282) is situated in the median line, near 
 the base of the brain, between the op- 
 tic thalmi (Z I, fig. 280) and in front of 
 the tubercula quadrigemina {fg) : it ap- 
 pears like a very narrow cavity, oblong 
 from before backward, and of greater 
 extent below than above ; it is not so 
 much a cavity as a fissure between the 
 two optic thalami. Vesalius compared 
 this ventricle to a valley, the hills on 
 either side of which were very closely 
 approximated to each other, and uni- 
 ted by a sort of bridge, represented by 
 the commissura mollis {h). 
 
 The superior orijice of the third ven- 
 tricle is surrounded by a white rim or 
 border (s), which forms, behind and on 
 either side, the peduncles of the pineal 
 gland. 
 
 The lateral walls {I, fig. 282) are plane, smooth, and of a gray colour ; they are formed 
 by two very distinct parts, viz., above and behind by the internal surface of the optic 
 ■thalamus, and below and in front by the internal surface of a gray mass, which appears 
 to me to deserve a particular description under the name of the gray mass of the third 
 ventricle. 
 
 That part of the internal wall of the ventricle which is formed by the optic thalamus 
 is marked off by a horizontal groove from the part formed by this gray mass. 
 
 The internal surface of this gray mass is smooth, and lined by the membrane of the 
 ventricle. The externed surface is continuous with the rest of the brain ; below, it forms 
 the tuber cinereum, or base of the infundibulum, passes around the corpora albicantia, 
 the anterior pillars of the fornix and their roots, is prolonged upward upon the sides ot 
 the septum kicidum, and downward as far as the upper surface of the optic commissure, 
 the posterior border of which is imbedded in this gray mass, and receives from it a short 
 white root on each side. 
 
 The lateral walls of the third ventricle are united together, opposite the anterior part 
 of the optic thalami, by a gray substance called the soft commissure, commissura rnollis (b), 
 the gray commissure, and also the vascular commissure of the optic thalami ; it varies much 
 lu size, and is very easily torn ; but I have always found the remains of it in those cases 
 
T®! NEUROLOGY. 
 
 in which it appeared at first sight to be wanting.* I regard the soft commissure as a 
 prolongation of the gray mass of the third ventricle, and this substance appears to me to 
 be of the same nature as the gray matter of the convolutions. 
 
 The floor of the third ventricle is of greater extent than the walls of that cavity ; it is 
 concave upon its upper or ventricular surface, and convex below. We shall divide it 
 into three portions : the posterior portion of the floor (above n, fig. 282) is deeply grooved 
 along the median line, forms an inclined plane sloping downward and forward, and cor- 
 responds to the interval between the peduncles of the cerebrum ; its white colour, which 
 is scarcely concealed by the thin layer of gray matter upon it, contrasts strongly with 
 the distinct gray colour of the lateral walls. The middle portion of the floor is funnel- 
 shaped, and corresponds to the corpora albicantia {z), and to the infundibulum (i) ; it leads 
 to the canal in the infundibulum. The anterior portion of the floor (m) is inclined down- 
 ward and backward, and is formed by a very thin, semi-transparent layer of gray sub- 
 stance {lamina cinerea), which we may call, with Tarin, the pars pellucida, and which is 
 supported by a fibrous layer derived from the pia mater. 
 
 In front, the third ventricle presents the anterior pillars {k,fig. 280, below I, and be- 
 hind c, fig. 282) of the fornix, in front of which is situated a white cylindrical cord (c), 
 directed transversely, and visible only in its middle portion ; this is the anterior commis- 
 sure, beneath which the ventricle extends as far as opposite the posterior border of the 
 optic commissure. Beliind the anterior pillars of the fornix, and somewhat above the 
 anterior commissure, are the two openings by which the third ventricle communicates 
 with the lateral ventricles {foramen Monroi) ; these openings (of which one is seen be- 
 tween b and k,fig. 282) are of an oval shape, are sometimes of unequal size, and become 
 much enlarged in chronic effusion into the ventricles. The two divisions of the ante- 
 rior extremity of the velum interpositum pass through these openings, to become con- 
 tinuous (at q q, fig. 278; with the choroid plexuses. Haller erroneously regarded them 
 as accidental ; an opinion that was founded upon several pathological observations, from 
 which it appeared that the lateral ventricles were distented with a considerable quantity 
 of fluid, while the third ventricle remained empty. 
 
 At the back part of the third ventricle is seen the posterior commissure {x, figs. 280, 
 282), a transverse cylindrical cord, situated in front of the tubercula quadrigemina, and 
 below the commissure of the pineal gland, with which it is continuous. The posterior 
 commissure is smaller than the anterior ; it may be regarded as a white commissure of 
 the optic thalami, for its extremities are lost in their interior. It forms a sort of bridge 
 above the anterior orifice of the aqueduct of Sylvius. 
 
 The Aqueduct of Sylvius. 
 
 The aqueduct of Sylvius, or aqueduct of the corpora quadrigemina, which was descn- 
 oed by both Galen and Vesalius, and by the latter quite as perfectly as by the anatomist 
 after whom it was named, is a canal which establishes a communication between the 
 third and fourth ventricles {I v,fig. 282) — iter a tertio ad quartern ventriculum ; it passes 
 through the isthmus of the encephalon, in the median hue, below the tubercula quadri- 
 gemina (/^). It is directed obliquely downward and backward. Its walls are dense, 
 and lined by the membrane of the ventricles. This canal presents both on its upper and 
 its lower wall a longitudinal groove or median furrow, bounded by two small longitudi- 
 nal cords. The median furrow on the lower wall is continuous with the longitudinal 
 gioove of the calamus scriptorius. The brothers Wenzel have given a minute descrip- 
 tion of these two furrows, and they have also noticed two lateral furrows. It was stated 
 by Vieussens that the opening of the aqueduct into the fourth ventricle was provided 
 with a valve. But his statement is at variance with the results of observation. 
 
 It follows, therefore, from the preceding description, that the third ventricle has four 
 openings, two of which communicate with the lateral ventricles, the third opens into the 
 fourth ventricle, and the fourth (between b and x, 380) leads into the infundibulum. 
 
 The third ventricle, moreover, has three conunissures : one composed of gray matter, 
 viz., the commissura mollis, or commissure of the optic thalami ; the other two of white 
 substance, one being anterior and the other posterior. 
 
 The Conarium, or Pineal Gland. 
 
 The conarium, pineal gland, or pineal body, is a small grayish body ( p, figs. 280, 282) 
 situated in the median plane, behind the posterior commissure of the third ventricle, and 
 between the nates, upon which it rests. 
 
 It is retained in this situation by two small medullary cords, which are Ccdled its ped- 
 uncles, and by the velum interpositum, below which it is placed, and by which it is almost 
 completely invested as with a closely-adherent sheath : the adhesion between these parts 
 is so intimate that they are almost always removed together ; and hence some anato- 
 mists have regarded the conarium as a dependance of that membrane, and others, who 
 
 * Out of sixty-six brains of subjects of all ages examined by the brothers Wenzel, the soft oommissure was 
 found in fifty-six. It was, therefore, wanting in ten cases. The facility with which it is lacerated may have 
 misled these industrious investigators into a belief that its absence was more frequent than it actually is. 
 
THE CONARIUM, OB PINEAL GLAND. /43 
 
 hare not been careful in their examinations, have declared that it is sometimes want- 
 ing in the human subject. This body, however, always exists in man and the mamma- 
 lia. It is wanting in birds and fishes, and in reptiles, with the exception of the tortoise, 
 in which it is so remarkably large that it forms by itself a kind of brain. — (Desmoulins, 
 Anat. dti Syst. Nerv., t. i., p. 211.) 
 
 This body is shaped like a cone, having its adherent base turned forward and its free 
 apex backward ; hence its name of conarium {Oribasius, Galen) ; it has also been com- 
 pared to a pine cone, and has been named the pineal gland, or jiineal body. Its form, 
 however, is subject to some variety ; it is sometimes spheroidal, and at other times cor- 
 diform, from being notched at the beise. 
 
 The pineal body is small, being only about four lines in length, and from two to three 
 lines wide at the beise. Its size, in the animal series, does not appear to bear any pro- 
 portion to the size of the cerebrum, or of the cerebellum, or of the tubercula quadrigem- 
 ina, so that comparative anatomy throws no light upon this obscure subject. Neither 
 age nor sex has any influence upon the development of this small body. 
 
 Relations. — The conarium or pineal gland, enclosed in the pia mater, Hke the cere- 
 brum and cerebellum, rests upon the slight triangular depression between the nates : the 
 venae Galeni run along its sides. 
 
 When stripped of the pia mater, it is free in all directions, excepting at its base, which 
 is connected with the encephalon by a transverse commissure, situated above the posteri- 
 or commissure of the cerebrum, and hy /our slender peduncles, two of which are superior 
 and two inferior. The superior peduncles (s, Jigs. 280, 282), which are the only ones gen- 
 erally described, form together a sort of loop, the two ends of which run along the tops 
 of the optic thalami ; they have been named the reins of the pineal body {habence). We 
 have already seen that they are continuous with the fornix. The inferior peduncles, 
 which are distinctly seen only upon a longitudinal vertical section through the middle of 
 the cerebrum, arise from the base of the pineal body, pass vertically downward upon the 
 back part of the internal wall of the third ventricle, and may be traced to the lower part 
 of that cavity.* 
 
 Colour and CoTisistence. — The reddish-gray colour of the pineal body contrasts strong- 
 ly with the whiteness of its commissure and peduncles. The colour and consistence of 
 this body exactly resemble those of the gray matter of the cerebral convolutions. If it 
 be compressed between the fingers, a viscid juice exudes, and certain small concretions 
 are found in it, which I shall notice after having described the structure of this organ. 
 
 Structure. — At the base of the pineal body are seen some white or medullary fibres, 
 which arise from the conuuissure and from the superior peduncles of that organ. These 
 white fibres spread out into a tuft, and terminate abruptly. All the rest of the conarium 
 consists of gray matter. On making a horizontal section of this body, it is sometimes found 
 to be solid, and sometimes to be hollow, and to contain a transparent, viscid fluid. The 
 cavity is lined by a vascular membrane, and, according to Meckel, by a layer of medul- 
 lary substance, which I have never seen. It has been stated that it communicates with 
 the third ventricle ; but I am inclined to believe, with Santorini and Gerardi, that the 
 conmiunicating orifice admitted by some authors is the result of traction upon the base 
 of the conarium in attempting to remove the pia mater. 
 
 When the pineal body contains no distinct cavity, which is not unfrequently the case, 
 the viscid fluid is distributed through it as through a sponge. 
 
 As to the nature of this body, it appears to consist of a soft gray substance, traversed 
 by a great number of bloodvessels, having a very close resemblance to the gray matter 
 of the brain, but none whatever to glandular tissues. 
 
 Concretions of the Conarium. — One of the most curious circumstances in regard to this 
 body is the existence in it of certain hard concretions, which Ruysch and others regard- 
 ed as small bones, an error which was successfully combated by Soemmering. The 
 use of them is utterly unknown. 
 
 Are these concretions constant 1 The brothers Wenzel found them wanting in six 
 brains out of one hundred. Soemmering states that he found them in fifteen brains, 
 among which were some of very young infants, and he adds that they exist in the foetus 
 before the full period. Meckel says they do not appear until the sixth or seventh year, 
 beyond which age he always found them. 
 
 These concretions sometimes form a single mass (acervulus, Sammering), resembling 
 a granular lump of salt ; sometimes, and most commonly, there are a great number of 
 them. 
 
 They appear as aggregated granules, which the Wenzels believed to be connected by 
 means of a proper membrane. . .' . 
 
 Seat of the Concretions. — When the pineal body is hollow, they are found in its interi- 
 or ; but when it is solid, they are situated upon the surface of this body. I have found 
 them several times upon its peduncles. 
 
 •■' Ridley describes certain white striae, arising from the pineal body, and terminating in the testes. Gall 
 Bays that the inferior peduncles are directed backward, and somewhat downward, to become continuou* with 
 the snb'acent white lamina. Plate xi., text, p. 223. 
 
m 
 
 NEUROLOGY. 
 
 They are of an opaline yellow colour in old subjects, and are whitish in the young. 
 According to Pfaff, they consist of phosphate of lime, carbonate of lime, and an animal 
 matter. 
 
 They were incorrectly regarded as morbid deposites by Morgagni, who supposed, with- 
 out proof, that they might produce cerebral affections of greater or less severity. 
 
 Function of the Pineal Gland. — The hypothesis of Des Cartes concerning the function 
 of this body, which was so completely refuted by Steno, is a striking example of the 
 abuse of an imperfect knowledge of anatomy ; according to Des Cartes, the soul is seated 
 in the pineal gland, and it directs all the movements of the body by means of the pedun- 
 cles, which he regarded as the gubernacula or reins of the soul. M. Magendie thinks 
 that this body performs certain functions having reference to the cerebro-spinal fluid : 
 he has regarded it as a kind of plug, which would obstruct the orifice of communication 
 between the third and fourth ventricles ; but, in the first place, it is completely fixed by 
 the pia mater ; and in the second case, even if it were free, it could not in any case close 
 the orifice alluded to. Morbid conditions of this body will perhaps throw some light upon 
 its functions, but they have not yet been sufficiently studied. The existence of a cavity 
 within the pineal gland, added to the fact that it is sometimes the seat of dropsy, would 
 seem to indicate that its functions are connected with secretion. 
 
 The Lateral Ventricles. 
 
 Dissection. — The lateral ventricles are exposed by the same dissection as that which 
 we have pointed out for the examination of the fornix and septum lucidum, that is to 
 say, by removing the upper parts of the hemispheres and dividing the corpus callosum 
 on each side of the median line (as in fig. 278, on the left side). In order to trace the 
 reflected portion or descending cornu, it should be laid open by cutting through its outer 
 wall from behind forward. There is also a great advantage in studying this part of the 
 lateral ventricles from the base of the brain. 
 
 The lateral ventricles {fig h,fig. 278) are two in number; they are much larger than 
 the other ventricles ; are placed symmetrically one on each side of the median line ; 
 they are separated from each other, but communicate through the medium of the third 
 ventricle ; their upper part is nearer to the base of the brain than to its upper surface, 
 and they approach still nearer to the base by their reflected portion or descending cornu. 
 
 Each lateral ventricle commences (/) in the substance of the anterior lobe (a), a little 
 in front of the third ventricle, and behind the anterior reflected extremity of the corpus 
 callosum (c), by which it is bounded in front ; from this point it passes vertically upward 
 and backward, describing a curve with its convexity directed inward ; having reached 
 (r) opposite the posterior part of the third ventricle, it changes its direction, so as to 
 turn downward and forward round the optic thalamus (/), and then terminates (h) in the 
 substance of the sphenoidal portion of the posterior lobe [i. c, in the middle lobe] (c) be- 
 hind the fissure of Sylvius, and, consequently, a little below and behind the point (/) at 
 which it commences. At the point of its reflection it also sends a prolongation (g) 
 backward into the occipital portion of the posterior lobe (J). From this it will be under- 
 stood why each lateral ventricle has been compared to a capital italic £ turned upside 
 down, and why the cavity is said to have three cornua, viz., an anterior or frontal (/), 
 an inferior, descending or sphenoidal (A), and a posterior or occipital cornu (g) ; on this ac- 
 count the lateral ventricles are frequently denominated ventriculi tricornes. 
 
 It is also seen that the ventricles are applied to each other at their anterior extremi- 
 ties, but diverge behind like the limbs of the letter x. 
 
 The general form of the lateral ventricles is very well shown upon a longitudinal sec- 
 tion of the cerebrum through the median line ; each of these ventricles is then seen to 
 be nothing more than an elliptical canal or passage, which runs around the large ellip- 
 soid mass formed by the optic thalamus and corpus striatum. This elliptical canal is 
 ooly interrupted below and in front opposite the fissure of Sylvius. Anatomists describe 
 in each lateral ventricle a superior portion, an inferior portion, and a posterior portion or 
 digital cavity. 
 
 The Superior Portion of the Lateral Ventricle. 
 
 This portion, called the body of the ventricle (i), is broader in front than behind, and 
 presents for our consideration a superior, an inferior, and an internal wall. 
 
 The superior uall, or the roof, is formed by the under surface of the corpus callosum. 
 
 The inferior wall, or the floor, is formed by the ventricular surfaces of the corpus striatum 
 (i) and optic thalamus {1} ; between these two bodies are found the lamina cornea and 
 t(eni& scmicircularis (m). 
 
 The Corpus Striatum. — When examined from the lateral ventricle, each of the corpora 
 striata (i i,figs. 278, 280) appears like a pear-shaped or conoidal eminence, having its 
 larger end turned forward, and its other end, which is very narrow, prolonged backward, 
 into the reflected portion of the ventricle. Its gray colour contrasts with the whiteness 
 of the surrounding parts. Its free surface is covered by the lining menibruiie of the ven- 
 tricles, and is very regularly marked by certain large veins which run neross it. 
 
THE LATERAL VENTRICLE. 745 
 
 The ventricular surface of the corpus striatum fonns only one portion of this body, 
 which has received its name from the white bundles or striee which traverse the gray 
 matter, of which it is principally composed. 
 
 The corpus striatum, considered as a whole, is an ovoid gray mass, lodged in a deep 
 excavation formed opposite the insula or island of Reil, which is situated in the fissure 
 of Sylvius, and which I propose to name the lobule of the corpus striatum. It will be seen, 
 hereafter, that the corpus striatum is covered on the outer side by the convolutions of 
 the insula, that it corresponds on the inner side with the optic thalamus and the gray 
 matter of the third ventricle, and that it is exposed below, at the back part of the ante- 
 rior lobes of the brain, behind the convolutions which form the sides of the furrow for 
 the olfactory nerve. 
 
 The aplic thalami {I I, Jig. 280), which, as we have already seen, constitute the lateral 
 walls of the third ventricle, form also, by their upper surface, a part {I, fig. 278) of the 
 floor of the corresponding lateral ventricle ; this surface, which is oblong from before 
 backward, conunences about six lines from the anterior extremity of the lateral ventri- 
 cle : it is covered by the choroid plexus ( p) and the fornix (k) : the corresponding ante- 
 rior pillar of the fornix turns round its anterior extremity, and the interval between the 
 pillar and the thalamus forms the opening of communication between the third and the 
 corresponding lateral ventricle. The brownish-white colour {couleur cafe au lait) of 
 the optic thalamus distinguishes it from the corpus striatum, which lies along its outer 
 side, the lamina cornea and the taenia semicircularis marking the limits between these 
 two bodies. 
 
 The lamina cornea is a thick, semi-transparent band, of a homy aspect, which was com- 
 pared by Tarin to a plate of horn, and which appears to be nothing more than a thick- 
 ened portion of the lining membrane of the ventricle. Beneath and protected by it is 
 found the vein of the corpus striatum, which receives the venous branches already de- 
 scribed upon the surface of that body. Beneath the vein is seen a small, white, linear 
 band («), to which Willis first directed attention as the limhus posterior, and which is 
 now called the tania semicircularis. 
 
 I would observe, that the lamina cornea and the taenia semicircularis are two very 
 distinct structures, which most anatomists have erroneously confounded. 
 
 More deeply, the limits between the corpus striatum and optic thalamus are marked 
 by a white layer, described by Vieussens as the geminum centrum semicirculare, or double 
 semicircular centre. 
 
 The lateral portion of the fornix and the choroid plexus (see fig. 278) must also be re- 
 garded as entering into the formation of the floor of the lateral ventricle. This lateral 
 portion of the fornix resembles a band applied upon the optic thalamus, but separated 
 from it by a fissure through which the choroid plexus becomes continuous with the ve- 
 lum interpositum :* the choroid plexus runs along the free edge of this band, and is some- 
 times turned up on to its upper surface. 
 
 The internal wall, or septum of the lateral ventricles, is much deeper in front, where it is 
 formed by the septum lucidum, than behind, where it consists of a small vertical portion 
 of the fornix, with which it terminates. We ought also to regard as forming a part of 
 the septum of the lateral ventricles a prolongation on each side of the gray matter of 
 the third ventricle, which passes round the corresponding anterior pillar of the fornix, 
 and upon the lower part of the septum lucidum. 
 
 The Inferior or Reflected Portion of the Lateral Ventricle. 
 
 Dissection. — ^As the reflected portion or descending cornu belongs to the base of the 
 brain, it is well to place the brain upon its convex surface, and then proceed to open it. 
 
 This cornu may also be reached from the great transverse fissure, by first removing 
 the pia mater which enters there, and then partially dividing the lower wall of the cornu 
 from the fissure of Sylvius backward, and turning back the lower wall on itself 
 
 The descending cornu {h,fig. 278) of the lateral ventricle has two walls, a superior and 
 an inferior. The superior wall {b,fig. 281) is concave, and, being moulded upon the pes 
 hippocampi or cornu ammonis (m), which forms the inferior wall, is named the sheath of 
 the pes hippocampi. 
 
 Upon the inferior wall are found the pes hippocampi or cornu ammonis, the corpus fim- 
 briatum, the fascia dentata, the great cerebral fissure, and the reflected portion of the choroid 
 plexus. 
 
 The cornu ammonis or ram's horn, pes hippocampi,i or foot of the sea-horse, is a conoidal 
 eminence {m,fig. 278)1: curved upon itself, and having its larger end turned forward, and 
 
 * [A comparison of Jigs. 1~S and 279 will facilitate the comprehension of this statement, in the latter ^^. 
 the fornix is reflected backward, and the continuity of the choroid plexus (p) with the velum (v) is shown.] 
 
 t [The term pes hippocampi is generally applied to the anterior part only of this structure, the whole being 
 usually called hippocampus major. 
 
 % 1 have not found, like Treviranus, the medullary substance of the anterior extremity of the cornu ammo- 
 nis either continuous or communicating in any manner with the external root of the olfactory nerve , I cannot, 
 therefore, admit that the functions of the cornu ammonis have any relation with those of the nerves in ques- 
 tion. Treviranus believes that it assists m the remembrance of olfactory impressions. It is unfortunate foi 
 
 5B 
 
7#6 NEUROLOGY. 
 
 its small end backward. Its concave border, which is directed inward and forward, is 
 bounded by a narrow, thick, and dense band, which forms a continuation of the posterior 
 pillar of the fornix ; mis is the tccnia hippocampi, so improperly named the corpus fimhri- 
 atum, OT fringed body («). 
 On raising up the taenia hippocampi {s,Jig: 281), there is seen beneath it a band of 
 Fig. 281. gray matter (d), which runs along the inner border of the cornu am- 
 
 monis : this gray matter, which is, as it were, crenated by transverse 
 furrows, has been well described by Vicq d'Azyr, under the name of 
 corps godronni, or fascia dentata. 
 
 To obtain an accurate idea of the cornu ammonis, it is necessary to 
 examine vertical sections of it, as was done by Vicq d'Azyr, who has 
 given very good figures of such sections : it is then seen (as in fig. 
 281) that the hippocampus major {m) is formed by a reflection of the 
 hemisphere inward upon itself, as the brothers Wenzel have very well 
 shown ; and that it is composed of a convolution doubled or turned 
 upon itself like a horn, so that the white convex part expands in the 
 interior of the lateral ventricle, while the gray concave part is upon 
 the surface of the cerebrum.* 
 
 The surface of a vertical section of the hippocampus major also pre- 
 sents a white spiral line (below m), which is the section of the white 
 covering of this eminence, and a rather thick gray layer (a), which is subdivided into two 
 smaller layers by a white streak (c) ; all these are arranged in a spiral manner. 
 
 The white layer which forms the covering of the cornu anamonis is continuous, on the 
 one hand, with that which lines the rest of the lateral ventricle, and on the other (by 
 means of the corpus fimbriatum, s) with the corpus callosum and the fornix. Not un- 
 frequently a second pes hippocampi is found on the outer side of the first, to which it is 
 concentric ; it is called pes accessorius {eminentia collateralis). Meckel erroneously re- 
 gards it as the result of an arrested development. 
 
 The inferior wall of the descending portion of the lateral ventricle farther presents for 
 our consideration, 
 
 The reflected or descending portion of the choroid plexus (see Jig. 278) ; and also the great 
 transverse fissure, through which the choroid plexus becomes continuous (opposite s,_^^. 
 281) with the external pia mater : the lower border of this fissure is formed by the hip- 
 pocampus major and corpus fimbriatum ; and the upper border by the lower surface of 
 the optic thalamus, which presents in this situation the corpus gcniculatum externum (j, 
 fig. 271), an oblong eminence, which is continuous with the optic tract, and the corpus 
 geniculatum internum (i), a small rounded eminence, which is circumscribed by the corpus 
 geniculatum externum. 
 
 The Posterior Portion of the Lateral Ventricle. 
 
 The digital or ahcyroid cavity {uyKvpa, a hook) is the occipital portion (g, fig. 278) of 
 the lateral ventricle. The term digital cavity has arisen from its having been compared 
 to the impression which the finger would leave if pushed backward into the substance 
 of the brain. It commences at the point where the ventricle is reflected upon itself, 
 passes horizontally backward, describing a curve with the convexity turned outward, and 
 becomes gradually narrower, until it terminates in a point. The dimensions of this 
 cavity are extremely variable, not only in different individuals, but even in the same sub- 
 ject. Thus, a very large digital cavity is often found on the right side, while on the left 
 there is only a trace of it. 
 
 Acute ventricular hydrocephalus affects the digital cavity more than any other part of 
 the ventricle, t In some cases the bottom of the digital cavity is not more than half a 
 line from the surface of the brain. 
 
 In the natural state, the upper wall of the digital cavity is exactly fitted to a conoidai 
 eminence, which occupies the lower wall or the floor of that cavity, and which differs in 
 its dimensions according to the size of the cavity itself This eminence (n), which is 
 variously named the unciform eminence, colliculus, calcar, unguis, was very well described 
 by Morandjt under the name of the ergot, and is therefore generally called the ergot of 
 Morand. 
 
 In form it rather closely resembles the hippocampus major, so that we ought, perhaps, 
 to prefer, with Vicq d'Azyr, the name of hippocampus minor. There is not only a cor- 
 respondence in form, but also in structure, between the two hippocampi ; and the broth- 
 ers W^enzel appear to me to have clearly shown that the ergot of Moraad, like the hip- 
 
 this hypothesis, that the animal in which the cornu ammonis is most developed, viz., the liare, is precisely 
 that in which there is least evidence of memory. 
 
 * I could never perfectly understand the structure of the cornu ammonis until I had eiamined it in rumi- 
 nantia and rodentia, but especially in the latter, in which it is most developed. In the rodentia the reflected 
 portion of the hemisphere is almost as large as the hemisphere itself, and the connexions of the cornu amnio- 
 nis with the fornix are seen most distinctly. It is quite evident that the fornix, the curnu ammonis, and the 
 corpus fimbriatum, form only one system of fibres, and are continuous with each other. 
 
 t It is probable that this is simply the mechanical effect of long-continued tying upon the back. 
 
 t Mem. de I'Acad. des Sciences, 1744. Observ. Anatomiques sur Quelques Parties du Cerveau 
 
THE CHOROID PLEXUSES, ETC. 747 
 
 pocampus major, is nothing more than a special convolution projecting into the ventri- 
 cle. It, in fact, consists of a white layer, enclosing a thick mass of gray substance. A 
 longitudinal anfractuosity, the depth of which depends on the prominence of the ergot, 
 denotes on the surface of the brain the situation of the digital cavity : this anfractuosi- 
 ty is constant, and I have already described it as the anfractuosity of the digital cavity. 
 There is also another circumstance which favours the analogy between the ergot and 
 the hippocampus major, and that is their continuity ; for there is only a depression be- 
 tween them, and the white layer which connects them is continuous in both cases with 
 the fornix. 
 
 Gredinsh as described several varieties of the ergot ; not unfrequently it is double, and, 
 as we have mentioned, so is the hippocampus major. The absence of the ergot is re- 
 garded by Tiedemann as the result of defective development. 
 
 The ergot and the digital cavity scarcely exist except in man, doubtless because he 
 alone has the occipital portion of the brain greatly developed. 
 
 The Choroid Plexuses. 
 
 The choroid plexuses of the brain, which have already been noticed in the descriptions 
 of the third and lateral ventricles, form a continuous system of vessels, as can be easily 
 shown by examining the brain from the base upward. Upon the under surface of the 
 velum interpositum, and on each side of the median line, are two small, red, granular 
 bands, running from behind forward, bordered by the veins of the corpora striata, and 
 terminating in front upon the convexity of an arch which forms the boundary of the ve- 
 lum in that direction. This arch is formed by the junction of the anterior extremities 
 of the choroid plexuses. It is situated behind the anterior pillars of the fornix, at the 
 point where those pillars unite, and is crossed at right angles by the veins of the corpus 
 striatum, which pass above it ; after this junction, the choroid plexuses again separate 
 and enter the lateral ventricles through the foramen (foramen of Monro) which leads 
 from the third to the lateral ventricles ; within each of the lateral ventricles they de- 
 scribe an elliptical curve {p, fig. 278), which is accurately moulded upon the optic thala- 
 mus, and runs along the fornix in the upper part of the ventricle, and along the corpus 
 fimbriatum in the descending comu or reflected portion. 
 
 The upper part of the choroid plexus is very narrow ; the lower part is three or four 
 times broader than the upper ; its upper and under surfaces are free, and also its outer 
 border, which contains a large vessel ; its inner border is continuous with the velum in- 
 terpostum* in the upper part of the lateral ventricle, and in the descending cornu with 
 the pia mater, at the base of the brain. 
 
 The lining membrane of the ventricle adheres intimately to the inner border of each 
 choroid plexus, so that the lateral ventricles are completely closed, and no fluid can es- 
 cape through the semicircular fissure which extends along their entire course. 
 
 The choroid plexuses are granular, or, rather, consist of vascular tufts, which are un- 
 like any other structure in the body, and their uses are quite unknown. 
 
 The Lining Membrane and the Fluid of the Ventricles. 
 
 The middle and lateral ventricles are lined by a transparent and tolerably strong mem- 
 brane, of which the horny lamina between the corpus striatum and thalamus opticus is 
 a part. On tracing this membrane from the third ventricle, it is seen to pass into the 
 lateral ventricles through the foramen (of Monro), behind the anterior pillar of the for- 
 nix. From the third ventricle it dso descends into the fourth through the aqueduct of 
 Sylvius. 
 
 It is extremely easy to demonstrate this membrane, especially upon the septum luci- 
 dum and corpora striata, and in the digiteil cavities. 
 
 In order to separate it to any extent, it must be dissected from without, by gradually 
 removing the layers of cerebral substance by which it is covered. This separation oc- 
 curs in acute ventricular hydrocephalus, in consequence of the pultaceous softening of 
 the surrounding tissue. In the foetus and new-born infant, this membrane can be sep- 
 arated with the greatest facility, on account of its density and the softness of the sur- 
 rounding parts. 
 
 Three questions present themselves regarding the ventricular membrane : Is it a se- 
 rous membrane 1 Does it communicate with the araclmoid, so that it ought to be re- 
 garded as a continuation of that membrane 1 How is it arranged along the fissure of 
 each lateral ventricle 1 
 
 That the ventricular membrane is a serous membrane is shown by the nature of the 
 fluid exhaled into the cavity of the ventricles ; by the structure of the membrane itself, 
 which consists entirely of lymphatic cellular tissue ; and by the diseases of the ventricles, 
 which are precisely similar to those of other serous cavities. + 
 
 * Compare figs. 278 and 279. 
 
 t The occurrence of acute aud chrouic serous eflTusions, of purulent formations, aud of miliary gr a nnla t l OM 
 in the ventricles, are proofs of the serous nature of their lining membrane. 
 [The ventricular membrane has a ciliated epithelium on its inner surface.] 
 
im 
 
 NEUROLOGY. 
 
 The number of veins which are situated beneath the ventricular membrane has sug- 
 gested the notion that it was a prolongation or continuation of the pia mater ; but these 
 vessels do not belong to the membrane. 
 
 The continuity of the ventricular membrane with the arachnoid on the surface of the 
 brain has not been demonstrated. I have already said that the so-called canal of Bichat 
 does not exist. 
 
 It has been stated that each lateral ventricle is divided, both in its direct and reflected 
 portions, by a circular fissure which turns round the optic thalamus, and through which the 
 pia mater becomes continuous with the choroid plexus. This fissure is closed by blood- 
 vessels, and some very dense cellular tissue, and in the interior of the ventricle by the li- 
 ning membrane, which is firmly attached on both sides of the fissure to the adherent 
 borders of the corresponding choroid plexus. It cannot be admitted that it passes from 
 one side of the fissure to the other, so as to enclose the plexus. 
 
 It is this membrane which prevents any fluid contained in the ventricles from infiltra- 
 ting into the sub-arachnoid cellular tissue at the base of tlie brain. 
 
 The very frequent coincidence of ventricular dropsy with the formation of false mem- 
 brane in the cellular tissue at the base of the brain shows the relation between that tis- 
 sue and the lining membrane of the ventricles, but by no means establishes the exist- 
 ence of any direct communication between the ventricular cavities and the cellular tis- 
 sue at the base of the brain. 
 
 The Ventricular Fluid. — The existence of a serous fluid in the ventricles was general- 
 ly admitted by the older anatomists, who named it pituita, and considered it to be an 
 excrementitious fluid, which was evacuated through the nasal fossae. During the last 
 century, anatomists were so convinced of its existence in all subjects, that they regard- 
 ed those cases in which it was not found as exceptions ; a recentissimis cadaveribus ahest 
 nonnunquam, says Haller, in speaking of an observation made by Verduc upon the brain 
 after death by decapitation. But the anatomists of the last century differed from the 
 ancients in regarding the existence of fluid in the ventricles as a post-mortem phenome- 
 non, depending on the condensation, by cold, of a vapour which, in their opinion, alone 
 exists in the ventricles during life. This vapour, the only use of which, according to 
 the view stated, would be to prevent adhesion of the opposite walls of the ventricles, 
 was compared by them to that which is found in the pleura, pericardium, and peritoneum 
 of a living animal. 
 
 The experiments of M. Magendie have proved the existence of a ventricular fluid du- 
 ring hfe ; and farther, that it may flow backward and forward into the spinal sub-arach- 
 noid space, through the opening (,y,fig. 282) in the lower part of the fourth ventricle. 
 
 The quantity of fluid in the several spaces found in the cranial cavity is extremely 
 variable, for it increases or diminishes according to the relative bulk of the brain in ref- 
 erence to the osseous case of the scull. 
 
 Having thus examined the brain by horizontal sections, made at different heights 
 from the convex surface towards the base, it is important, in order thoroughly to under- 
 stand the parts we have described, to study them under different aspects, either by means 
 of particular sections, or by the aid of the various methods adopted by different anato- 
 mists. 
 
 Jt Median Vertical Section of the Brain. 
 
 Upon this section {fig. 282), which divides the brain into two perfectly similar halves, 
 p- 2g2 a great many objects 
 
 are seen : and first, 
 the optic thalamus 
 and corpus striatum, 
 which might be said 
 to form the central 
 nucleus or root of the 
 cc-ebrum. 
 
 The optic thalamus 
 is now seen to be 
 smooth and free on its 
 inner surface, where 
 it forms the lateral 
 wall (0 of tlie third 
 ventricle ; it is con- 
 vex and free above, 
 where it forms part 
 of the floor of the lat- 
 eral ventricle, and it is also free below, where it presents to our notice the corpora ge- 
 niculata. Behind, it is continuous with the tubercula quadrigemina, and in front with 
 the corpus striatum ; on the outer side it is blended with the corresponding cerebral 
 
VERTICAL SECTION OF THE BEAIN. 749 
 
 hemisphere, and below it is deeply notched for the reception of the corresponding cere- 
 bral peduncle. 
 
 The corpus striatum forms a concentric curve along the outer side of the opic tliala- 
 mus ; it commences in front by a large pyriform extremity, duninishes in size as it pro- 
 ceeds backward, and terminates in a very narrow gray band, which turns round the op- 
 tic thalamus as far as the termination of the descending cormi of the lateral ventricle, 
 I e., as far as the large end of the cornu ammonis. 
 
 The- lateral ventricle forms a circular or elliptical trench around this central nucleus, 
 formed by the thalamus opticus and corpus striatum (see fig. 278). It commences in the 
 substance of the anterior lobe of the cerebrum {anterior or frontal cornu), mounts up upon 
 the corpus striatum, passes horizontally backward, and, becoming widened, divides into 
 two prolongations : one horizontal (digital cavity, occipital or posterior cornu), which dips 
 into the substance of the posterior lobe, and terminates near the surface of the brain ; 
 the other reflected, which runs from behind forward, and terminates behind the iissure of 
 Sylvius, so that the lateral ventricle would describe an almost complete ellipse if it were 
 not for the layer of cerebral substance which forms the bottom of the fissure of Sylvius, 
 and which separates the commencement (/) from the termination (Ji) of the ventricle. 
 
 Upon the longitudinal section is also seen the regular curve of the corpus callosum (e 
 df,fig. 282), which nuis around the central nucleus. The unequal thickness of the dif- 
 ferent parts of the corpus callosum, its reflection in front so as to embrace the anterior 
 extremity of the corpus striatum, its posterior enlarged extremity or protuberance, and 
 its continuity with the fornix, are shown ; and farther, it is seen that the space between 
 the corpus callosum and the central nucleus of the brain constitutes the upper part of the 
 lateral ventricle, and that the interval between the cornu ammonis and the nucleus con- 
 stitutes its reflected portion. 
 
 In this section we also notice the septum lucidum (J,), the fornix (A), the mammillary tu- 
 bercle (c), the tuber cinereum, the gray commissure (i) and gray mass of the third ven- 
 tricle, the infundibulum (i), the optic nerve (2), the section of the anterior commissure 
 (c), also that of the posterior commissure {x), and the peduncle («) of the pineal gland {p). 
 
 The longitudinal section also shows that the third ventricle is formed by the juxtapo- 
 sition of the two central nuclei of the cerebral hemispheres ; that these hemispheres are 
 only connected to each other by the corpus callosum and the commissures, and there- 
 fore that it is by studying these parts that the system of communicating fibres between 
 the two hemispheres is displayed. 
 
 It is moreover seen that each hemisphere may be regarded as composed of a white 
 and gray covering which surrounds a central nucleus. And it is between the general 
 central nucleus and the hemispheres, or, rather, between the fornix and its prolongations 
 on the one hand, and the optic thalami on the other (as at s,fig. 281, for example), that 
 the ventricles would communicate with the exterior if the ventricular membrane were 
 not firmly attached to the choroid plexus : it is also in the same situation that the exter- 
 nal pia mater passes into the internal. 
 
 The Central Nucleus. — A very curious preparation may be very easily made upon this 
 vertical median section, to show the central nucleus separated from the other parts. If 
 the handle of a scalpel be introduced between the corpus striatum and the reflected por- 
 tion of the corpus callosum, it will be found that the ventricular membrane is the only 
 means of connexion between them, and that the corpus callosum forms, at this point, a 
 sort of outer case of medullary substance for the corpus striatum, the entire anterior 
 portion of which may be exposed without breaking through any connecting fibres. The 
 anterior part of the corpus striatum znay also be exposed from below, that is to say, by 
 dissecting from the base of the anterior lobe of the cerebrum towards the lateral ventri- 
 cle ; for this purpose, the handle of the scalpel must be inserted along a curved whitish 
 line, the concavity of which is turned forward, and which limits the anterior lobe behind. 
 
 The corpus striatum can be completely isolated only in front and opposite the fissure 
 of Sylvius, in which situation it is covered by only a slight thickness of cerebral sub- 
 stance, which is seen to consist of four very distinct layers, viz., the external gray layer 
 of the convolutions ; a very thin white layer ; an equally thin gray layer ; and, lastly, 
 another layer of medullary substance. 
 
 Transverse Vertical Sections. 
 I am in the practice of making five transverse sections of the cerebrum : the first, im 
 mediately in front of the corpus callosum ; a second through the largest part of the cor- 
 pora striata ; a third through the anterior part of the optic thalami ; a fourth through the 
 middle of the thalami ; and a fifth through the occipital portion of the posterior lobes. I 
 shall not here enter into a detailed description of these several sections, which appeal 
 to me to convey a more correct idea of the structure of the brain than any other sec- 
 tions, but which cannot be well understood without figures. They disclose, in fact, a 
 medullary centre giving ofll' three or four prolongations of white substance, which con- 
 stitute, in their turn, the medullary centres of a certain number of convolutions to which 
 they are distributed ; this ramified disposition of the me;iullary substance warrants the 
 
^W NEUROLOGY. 
 
 application of the tern arbor vita of the cerebrum to the appearances seen upon these dif- 
 ferent sections. 
 
 The most interesting of these sections is undoubtedly that which passes through the 
 cerebral peduncles, and which discloses the following appearances : 
 
 Each hemisphere is formed by a medullary centre, which gives off three principal pro- 
 longations, around which all the convolutions are arranged, and are thus collected into 
 three groups, viz., a superior, an external, and an inferior group ; the last of these is con- 
 nected with the medullary centre by a long narrow pedicle which corresponds to the 
 white matter on the outside of the corpus striatum. The corpus striatum and optic 
 thalamus are situated opposite to this pedicle or prolongation of the medullary centre. 
 
 The medullary centres of the two hemispheres are connected together by the corpus 
 callosum, which forms an arch with the concavity directed downward. Moreover, either 
 the section of the septum lucidum, or of the fornix, is seen according to the point at which 
 the knife has been carried through. 
 
 The transverse section through the corpora striata and optic thalami deserves special 
 attention. If the section be made through the anterior part of the corpus striatum, and 
 therefore in front of the optic thalamus, the former body presents an oval gray surface, 
 dotted with white points, which are sections of medullary fibres ; the middle of this oval 
 surface is traversed by a series of small, parallel, white fasciculi, which are sections of 
 the medullary bands that pass through the corpus striatum. On the outer side of the 
 corpus striatum are seen distinctly the four layers formerly mentioned as corresponding 
 to the island of Reil. The white layer which turns round the outer surface of the corpus 
 striatum may be said to be reflected upward to form the septum lucidum. 
 
 Several of these sections appear to me to show that certain white fibres, which arise 
 in the interior of the corpora striata, pass to the circumference of the optic thalami ; or it 
 may be said that certain white fibres arise in the optic thalami, spread out, and are lost 
 in the substance of the corpora striata, beyond which it is impossible to trace them. 
 This beautiful section suggested to M. Foville* some ideas respecting the structure of 
 the brain, to which I shall presently have occasion to refer. 
 
 The Section of Willis. 
 
 Previously to the time of Varolius and Willis, anatomists were contented with making 
 successive horizontal sections of the brain from the vertex towards the base, and study- 
 ing minutely the parts thus exposed ; and each anatomist believed that he had described 
 different objects when chance presented him with some arrangement that had not been 
 previously described. Willis insisted upon the necessity of carefully removing the mem- 
 branes from the surface of the brain, and he objected to the usual method of examining 
 this organ by making sections, which destroy the connexions between its different parts ; 
 he considered the brain to be composed of farts folded upon themselves, collected into a 
 globular form, and connected to each other by mutual prolongations. He also pointed 
 out the importance of first examining the brains of animals, which are much more sim- 
 ple than the brain of man, the size and complexity of which render its study one of great 
 difficulty. 
 
 After having made these judicious remarks, Willis proceeds to describe the following 
 mode of making the section which he had contrived, for the purpose of unfolding the 
 cerebrum and opening out this spheroidal mass into a flat surface :t 
 
 Place the brain, completely stripped of its membranes, upon its convex surface ; turn 
 forward the cerebellum and the medulla oblongata ; introduce the knife into the fissure 
 of Sylvius, and carry it backward as far as the digital cavity ; a flap will thus be detached, 
 comprising all the lower wall of the descending comu of the lateral ventricle. Repeat 
 this section on the opposite side ; and, after having turned backward the flaps thus form- 
 ed, another section must be made on each side of the brain, extending from behind for- 
 ward along the corpus striatum, on a level with the outer border of the corpus callosum, 
 and reaching to the anterior extremity of the lateral ventricle. Turn forward the inter- 
 mediate flap, which wiU comprise the cerebellum, the pons Varolii and peduncles, the 
 optic thalami, and the corpora striata. 
 
 The whole of the interior of the ventricle is thus exposed, so that we can examine the 
 lower surface of the corpus callosum, and its continuity with the centrum ovale of each 
 hemisphere, or the centrum ovale of Vieussens seen from below. The continuity of the 
 fornix with the comu ammonis is also well displayed. J 
 
 * Note sur la Structure du Cerveau, 24e Bulletin de la Soci6t6 Anatomique. — {Nouvelle Bihliolheque Midi- 
 cale. ) 
 
 t Tlie brains of animals being much less complicated than that of man, are more convenient for this purpose. 
 The brain of a sheep thus unfolded is represented by Willis in his Cerebri Analome, fig. vii. 
 
 t This section, which, however, like all similar methods, is liable to the objection that it destroys the con- 
 nexion of parts, suggested toM. Laurencet the idea of comparing the cerebral mass to a nervous loop, analo- 
 gous to the loops described by MM. Prevost and Dumas as forming the terminations of the nerves. According 
 to this view, the nervous system would represent an elongated ellipse, one end of which would be represented 
 bv the brain and the other by the extremities of all the nerves ; but both loops are equally inadmissible. 
 
GALL AND SPURZHEIM S VIEWS OF THE BEAIN. '^?tfl 
 
 General Remarks upon the Method of examining the Brain by successive 
 
 Sections. 
 
 The method of examining the brain by successive sections has been carried farthest 
 by Vicq d'Azyr, whose beautiful plates are entirely devoted to the demonstration of the 
 objects seen upon various sections of the brain made in succession either from below or 
 from above. This method unfolds to us the relative disposition of the gray and white 
 substances, shows the manner in which the ventricles are formed, and displays to us the 
 real nature of parts which, in consequence of their projecting and being free at some 
 part of their surface, have received particular names. 
 
 But this mode of examining the brain can only be regarded as a preUminary means 
 calculated to give an idea of this organ as a whole ; and it tends to perpetuate the er- 
 roneous opinion that the brain is a pulpy mass, consisting of a semi-fluid substance, and 
 displaying no more evidence of contrivance in its structure than a ball of wax. 
 
 The method adopted by Varolius and Vieussens, which fell into disuse after the pub- 
 lication of the beautiful work of Vicq d'Azyr, and which consisted in determining the 
 connexion of the different parts of the brain, has been revived and improved by Gall 
 and Spurzheim, who have thus opened up the path which modern anatomists have so 
 eagerly pursued. 
 
 Methods of Varolius, of Vieussens, and of Gall, or the Examination of the 
 Connexions of the Different Parts of the Brain. 
 
 Varolius was the first to perceive that the essential point in the study of the brain was 
 to ascertain the connexion of its several parts. He was also the first who dissected the 
 brain from below, and who specially examined its connexion with the spinal cord ; he 
 described the spinal cord as originating from the brain, not opposite the foramen mag- 
 num, but from the lower part of the cerebral ventricles. 
 
 Vieussens traced the bundles of the pyramids through the pons Varolii to the pedun- 
 cles of the brain, and followed these peduncles through the optic thalami and the corpora 
 striata into the centrum ovale, which is named after him. But there his inquiries ended, 
 for, according to him, it was in this centre that the linear or radiated structure termina- 
 ted ; and his preconceived notion of a nervous centre (centrum ovale), from which, with 
 Varolius, he described all the fibres as proceeding downward, prevented him from carry- 
 ing his researches farther. 
 
 Gall followed up the investigations of Varolius and Vieussens, but instead of dissect- 
 ing the fibres from above downward, or from the brain towards the medulla, he traced 
 them from below upward, or from the medulla towards the brain, and followed them 
 through the centrum ovale as far as the convolutions. 
 
 The method adopted by Gall in order to separate the fibres of the cerebrum and show 
 their connexions was to scrape them with the handle of a scalpel. But, from the nature 
 of this proceeding, only those white fibres can be conveniently traced which pass through 
 gray matter, but the white fibres themselves can never be separated from each other. 
 Hardening the brain in strong alcohol, in nitric or muriatic acid, or by boiling it in oil, or 
 by macerating, or boiling it in a solution of salt, facilitates the separation of its fibres ; 
 but, as the results obtained in these modes might be considered as purely artificial, the 
 action of a stream of water is preferable to any of them. 
 
 The results obtained by acting on the brain by streams of water fully confirm those 
 which are arrived at by the examination of the hardened brain. 
 
 Again, the anatomy of the fcEtal brain and comparative anatomy have also aided in 
 throwing light upon the connexion between the different parts of the brain. 
 
 As the works of Gall were the commencement, if not the foundation, of all that has 
 since been done, I have thought it necessary to give a brief summary of his views re- 
 garding the structure of the brain ; and as a knowledge of its structure consists in a great 
 measure in that of its connexions with the cerebellum and spinal cord, the examination 
 of these two subjects cannot properly be separated. 
 
 Gall and Spurzheim' s Views of the Structure of the Brain, 
 Gall and Spurzheim commence by stating, 1. That as the brain consists of several 
 departments, the functions of which are totally different, there are several primitive fas- 
 ciculi which, by their development, assist in the formation of that organ. 2. That these 
 fasciculi are composed of medullary fibres arising successively from the gray matter, 
 which, with Vicq d'Azyr, they regard as the matrix or generator of the white substance. 
 3. That there exist in the brain a formative system of fibres, or a formative apparatus, 
 and systems of uniting fibres, called commissures. In the first, or formative system, 
 Gall describes four primitive fasciculi ; namely, the anterior pyramids, the posterior 
 pyramids, the olivary fasciculi, the longitudinal fasciculi, which assist in forming the fourth 
 ventricle, and some others which are yet imperfectly understood.* 
 
 * It win be observed that Gall's fundamental statements are hypothetical : that the brain is developed from 
 certain primitive fasciculi, that there is a successive increase of these fasciculi from below upward, and that 
 
752 
 
 NEUROLOGY. 
 
 Formative Sijstem of Fibres. — The anterior pyramidal fasciculi decussate at their origin, 
 but the other fasciculi arise on the same side as the hemisphere to which they belong. 
 
 The anterior pyramidal fasciculi {h',figs. 273, 274) are re-enforced as they pass through 
 the pons Varolii (m), which is tljerefore, according to Gall's view, a ganglion, named by 
 him the ganglion of the anterior pyramidal fasciculi ; these pyramidal fasciculi constitute 
 the cerebral peduncles {x, fig. 283), and diverge (y y') so as to enter the inferior, ante- 
 rior, and external (i and m, fig. 284) convolutions of the anterior and middle lobes. 
 
 Gall, in his beautiful plate. No. V., shows the expansion of the fibres of the peduncles, 
 their distribution, their unequal lengths, and the manner in which their expanded ex- 
 tremities are covered with gray matter to form the convolutions. 
 
 It still i-emains to determine how the superior convolutions and those of the posterior 
 lobe are formed : the following are the statements of Gall on this point : 
 
 The olivary bodies of the medulla oblongata are nothing more than ganglia, from each 
 of which a very strong bundle, the olivary fasciculus (see p. 708), emerges, and ascend- 
 ing behind the pons, where it is considerably re-enforced, passes through the gray mat- 
 ter which lies upon the white fibres of the cerebral peduncle, where it again receives 
 some additional fibres ; this gray matter constitutes a rather firm ganglion on each side ; 
 these are the optic thalami, which, according to Gall, do not assist in the formation of 
 the optic nerves, and bear no proportion to them in size. 
 
 The olivary fascicuh, which are divided into very delicate filaments in traversing the 
 optic thalamus, are again collected together as they emerge from its upper border. 
 They then pass through a thick mass of gray matter, the corpus striatum, half of which 
 projects into the ventricular cavity, while the other half is surrounded by the convolu- 
 tions of the island of Reil. The radiated fasciculi {k, fig. 284) are again re-enforced in 
 traversing the corpus striatum, which is regarded by Gall as another ganglion, and are 
 then sufficient to form all the posterior convolutions, and also those which are situated 
 along the upper border of each hemisphere, in the median line (A h h). 
 
 It therefore follows, according Gall, that the convolutions are nothing more than the 
 
 Fig. 283. 
 
 perfecting of all the preceding structures, which 
 should be regarded as preparatory systems of fibres 
 destined to form a whole. 
 
 Uniting System of Fibres or Commissures. — Even 
 the oldest anatomists regarded the corpus callo- 
 sum as the connecting medium between the two 
 hemispheres ; Vicq d'Azyr, who described several 
 other commissures besides the corpus callosum, 
 regarded them as intended to establish sympathet- 
 ic connexions between the different parts of the 
 brain. Gall, taking a more comprehensive view 
 of this subject, attempted to determine what parts 
 of the brain were connected by this means, and to 
 discover the general law which governs the ar- 
 rangement of the commissures, wliich he believ- 
 ed to be formed by a system of fibres and bundles, 
 named by him faisceaux rentrans ou convergent. 
 
 We have seen that Gall traces the pyramidal 
 and olivary fasciculi to the gray matter of the con- 
 volutions. According to him, all the extremities of 
 the medullary fibres penetrate the gray matter, 
 which is therefore whiter internally than on the 
 surface. Gall acknowledges that he has not been 
 able to determine their ultimate distribution ; he 
 does not know whether they terminate in the gray 
 matter, or turn back again towards the interior. 
 Nevertheless, he considers it very probable that 
 new medullary filaments originate in this gray lay- 
 er, and that there is thus produced a system of fibres 
 which re-enforces the preceding one, and is connected 
 with it internally.* 
 
 the graysubstance is the matrix of the white, are so many suppositions. Of the primitive fasciculi, the anterior 
 pyramids alone are well defined ; the inaccuracy in the representation of the posterior pyramids disfigures his 
 sixth plate. 
 
 * Nothing certain appears likely to arise from this proposition, and yet Gall immediately adds (p. 202), " It 
 is certain that the existence of two systems of fibres in the brain can be distinctly demonstrated, and that the 
 converging system contains more fibres and stronger fasciculi than the radiating system." On seeking for 
 his proofs, we find that he infers that converging filires must necessarily exist, from the disproportion between 
 the white matter of the hemispheres and the fibres which come to them from the fasciculi of origin. "The con- 
 verging fibres,'" says he, " at the bottom of all the convolutions, are see« to enter between the diverging fibres, 
 and interlace with them." It is very evident, from an examination of the proofs adduced by Gall in support 
 of the existence of converging fibres, that the distinction between the converging and diverging fibres is purely 
 hypothetical. 
 
GENERAL IDEA OF THE BRAIN. 
 
 According to Gall, the commissures are, the corpus callosum, the fornix, and the ante- 
 "ior and posterior commissures. 
 
 The corpus callosum {fd e,Jig. 283) is intended to unite the convolutions of the two 
 hemispheres. Its anterior reflected portion unites the inferior convolutions of the two 
 anterior lobes (fp a a). The enlarged posterior extremity (e) receives the fibres (s «) 
 of the posterior convolutions (b) and the middle portion of those of the middle convolu- 
 tions (c). 
 
 The anterior commissure, which can be so easily traced {m) through the corpus stria- 
 tum into the convolution of the sphenoidal extremity of the posterior [middle] lobe, is 
 regarded by Gall as the means of connecting certain corresponding convolutions in the 
 sphenoidal portions of the two posterior [middle] lobes. 
 
 The posterior commissure, which is lost in the substance of the optic thalami, and 
 which is much smaller than the anterior, fulfils the same purpose for those bodies. 
 
 The posterior pillars (k) of the fornix are regarded by Gall as forming a commissure 
 for the posterior convolutions of the two middle lobes. The fornix appears to him to 
 result from the connexion of these parts, and he considers the interlacement called the 
 lyra to be composed of the connecting filaments. His error here is evident, for the for- 
 nix results from the juxtaposition of two medullary cords. The fornix may be regarded 
 as an antero-posterior (A h), but not as a transverse commissure. 
 
 The Ventricles and Convolutions. — The formation of ventricles is considered by Gall to 
 be the necessary result of the divergence of some fasciculi and the convergence of others. 
 
 His description of the convolutions is entirely new, and one cannot but regret that it 
 should be disfigured by the hypothesis of converging and diverging fibres. The follow- 
 ing is his mode of describing these parts, which he regards as the completion and final 
 object of the organization of the brain, and as performing the nlbst elevated functions. 
 
 Gall admits two layers in each convolution ; and he finds that these two layers can 
 always be readily separated, but only in the median line. He successfully proves, in op- 
 position to the commission of the Institute, that the convolutions are not composed of a 
 white, soft, and pulpy matter, resembling pomade or jelly, but that they have a fibrous 
 or linear structure.* 
 
 Unfolding of the Cerebrum. — The idea of unfolding the brain, which is nothing more 
 than opening out the convolutions, was derived by Gall from his view of the structure of 
 the convolutions, which he regarded as formed of two layers united by very delicate cel- 
 lular tissue. It was eilso suggested to him by the examination of hydrocephalic brains, 
 in which he conceived there was no disorganization, but merely an unfolding of the con- 
 volutions. 'Die following is his method of unfolding the brain : after having very care- 
 fully removed the meninges, he introduced his fingers into the great transverse fissure 
 between the optic thalamus and the hippocampus major, and thus penetrated into the 
 lateral ventricles : he then pressed gently against the outside of the ventricles ; he broke 
 down the white matter of the hemispheres until he reached the base of the convolutions, 
 which then necessarily became unfolded, so as to be moulded upon the back of his hand ; 
 the astonished spectators would have wondered less if they had seen the lacerations ne- 
 cessary to produce this result. 
 
 The unfolding of the brain is impossible if Gall's views be correct ; for, according to 
 him, the white fibres of the brain are not all of equal length, and those which correspond 
 to the anfractuosities are much shorter than those corresponding to the convolutions ; 
 besides, I am convinced that, in hydrocephalus, the convolutions are not unfolded, but 
 are atrophied, flattened, and compressed against each other. 
 
 Such are the principal ideas of Gall regarding the structure of the brain, t His system 
 undoubtedly contains numerous errors and imperfections ; but, nevertheless, it has estab- 
 lished a new era in the study of the anatomy of this organ. 
 
 General Idea of the Brain. 
 
 1. The decussation of the pyramidal fasciculi of the medulla oblongata, their passage 
 through the pons Varolii, their continuity with the cerebral peduncles, of which they 
 form the lower portion, their passage through the optic thalamus, and their expansion 
 within the corpora striata {k, fig. 284), through which they may be traced (A h h) as far 
 as the convolutions, are incontestable facts. 
 
 2. Again : it is no less certain that the fascicuU of re-enforcement of the medulla are 
 
 * See note, p. 75S. 
 
 t The following is the completion of these ideas : 1. As the peripheral extremities of the nerves expand in 
 all the organs of our body to form an immense surface (and of this expansion the retina is an excellent exam- 
 ple), so do the primitive fasciculi of the brain, after being re-enforced in their passage through the different 
 masses of gray substance, finally expand in the convolutions, and receive a covering of gray matter. 2. There 
 are as many particular systems as there are different functions, but they are all connected together by anas- 
 tomoses. 3. The nervous system is double, but is united into one whole by the commissures. 4. There is 
 not, and there cannot be, any common centre of all the sensations, thoughts, and volitions. 5. Personal unity 
 will always remain a mystery. 
 
 Each of these propositions might form the subject of ample commentary. I will merely remark the incon- 
 gruity between the acknowledged fact of personal unity, and the singular proposition that there neither i^ 
 nor can be, any common centre of all the sensations, tlioughts, and volitions. 
 
 5C 
 
754 
 
 NEUROLOGY. 
 
 prolonged above tliB'JiSftS into the cerebral peduncles, of which they form the upper poi- 
 tion {x, Jig. 283), and become continuous, without any line of demarcation, with the optic 
 thalamus. Do these fasciculi decussate 1 They remain distinct until they reach oppo- 
 site the pons, behind the tubercula quadrigemina, where they unite ; they appear to me 
 to decussate, but not so evidently as the anterior pyramids, and I cannot venture to state 
 this positively. 
 
 3. Fasciculi of white fibres radiate in all directions (y y',Jig. 283) from every part of 
 
 Fig. 284. the surface of the optic 
 
 thalamus (g g), excepting 
 its inner side, which is 
 free, and corresponds to 
 the third ventricle ; the an- 
 terior of these fibres pass 
 directly forward, the mid- 
 dle fibres outward, and the 
 posterior fibres backward, 
 forming the radiating 
 crown of Reil (k,fig. 284). 
 As these radiating fibres 
 emerge from the optic tha- 
 lamus, they are bound 
 down, as it were, by cer- 
 tain white curved fibres, 
 which constitute the tsenia semicircularis. 
 
 4. All the white fasciculi of the corpora striata, excepting those which are continuous 
 with the anterior pyramids, proceed from the optic thalami. Some of them appear to 
 me to terminate in the corpora striata in the form of extremely delicate filaments, but 
 the greater number pass through the corpora striata without either increase or diminu- 
 tion, and then pass into the hemispheres. The corpora striata of Willis are, therefore, 
 nothing more than gray pulpy masses, which are traversed both by the white fibres ra- 
 diating from the circumference of the optic thalami, and by those which are derived from 
 the anterior pyramids. The gray matter is not arranged in alternate linear stris with 
 the Avhite substance. So far from thinking, with Reil, Gall, and Tiedemann, that the 
 fibres which emerge from the corpora striata are much more numerous than those which 
 enter it, I have been led to a precisely opposite conclusion, namely, that a certain num- 
 ber of fibres, proceeding from the optic thalami, terminate in the interior of the corpora 
 striata, the gray matter of which, in reference to these fibres, represents the gray sub- 
 stance in the convolutions. 
 
 5. From the anatomical fact that a certain number of white fibres terminate in the 
 corpora striata, and also from the size of those bodies being in some animals inversely 
 proportioned to that of the hemispheres, it appears to me to follow that the corpora stri- 
 ata may be regarded as internal convolutions, in which a certain number of medullary 
 fibres terminate.* 
 
 6. It is extremely easy, by means of a stream of water, to separate, and, as it were, 
 enucleate the corpus striatum from the sort of shell formed for it by the cerebrum oppo- 
 site the fissure of Sylvius. The corpus striatum is only connected with the cerebrum 
 by the radiating fibres which emerge from its upper circumference near the corpus cal- 
 losum. 
 
 The optic thalamus and its fasciculus of origin present no trace of a linear structure. 
 Nor can we discover in it the concentric layers admitted by Herbert Mayo. With a lit- 
 tle attention, certain extremely delicate white filaments are seen in the optic thalamus, 
 which cannot be separated, on account of their tenuity and the adhesion of the surrounding 
 tissue to them. If the term ganglion be applicable to any part of the cerebrum, it cer- 
 tainly is so to the optic thalamus ; for a nervous ganglion is nothing more than a pecu- 
 liar apparatus in which nervous filaments become separated and spread out, in order to 
 enter into new combinations. We must agree with Reil and Tiedemann in regarding 
 the optic thalami as appendages of the cerebral peduncles : Tiedemann calls them the 
 enlargements of the cerebral ■peduncles. 
 
 7. The essential points to be made out in the structure of the cerebrum are the ulti- 
 mate course of the fibres radiating from the optic thalami and corpora striata, and the 
 relations of those fibres with the convolutions of the brain and the corpus callosum. I 
 by no means agree with Reil in thinking that we must not attach so much importance to 
 the continuity of fibres in the cerebrum, and that their contiguity is a sufficient guide to 
 its anatomy : on the contrary, I regard the determination of their continuity as the key 
 to the structure of this organ. 
 
 8. There is no median raphe in the corpus callosum, the right half of its transverse 
 fasciculi being continued into the left half, without any line of demarcation. 
 
 * In several cases of chronic hydrocephalus, in which the hemispheres were reduced to a very thin lamina. 
 I have found the optic thalami atrophied, and the corpora striata of enormous size. 
 
GENERAL IDEA OF THE BRAIN. 755 
 
 9. It appears, at first sight, that the fibres of the corpus callosum {edf,fig. 284), and 
 the white radiating fibres (k), which emerge from the optic thalami and corpora striata, 
 decussate (as at g) ; but on separating the fibres of the cerebrum, either after it has been 
 hardened in alcohol or by the action of a stream of water, it is most distinctly shown 
 that these two sets of fibres are continuous. 
 
 10. Again : the continuity of the fibres of the corpus callosum with those of the hem- 
 ispheres is no less evident ; the middle fibres {,s,fig. 283) of the hemispheres are seen 
 to pass transversely inward, the anterior fibres (a p) backward, the posterior fibres («) 
 forward, and the inferior fibres to bend and turn upward, to become continuous with the 
 corpus callosum. 
 
 I have in vain endeavoured to determine by actual dissection whether there is a de- 
 cussation of the fibres of the corpus callosum itself; I still entertain many doubts regard- 
 ing this subject ; we shall presently find, when speaking of the development of the brain, 
 that the corpus callosum does not appear until after the hemispheres ; and that compara- 
 tive anatomy, by showing that the corpus callosum does not exist in the three lower 
 classes of vertebrate animals, is opposed to the idea that the hemispheres are composed 
 of certain fibres which decussate in the corpus callosum. 
 
 11. The doctrine of converging and diverging fibres, advanced by Gall and Reil,* can- 
 not explain the continuity of the fibres of the corpus callosum with the radiating fibres 
 of the corpora striata and optic thalami. 
 
 Tiedemann, from his researches into the anatomy of the foetal brain, states that the 
 corpus callosum is formed by the reunion of the fibres of the cerebral peduncles after 
 they have expanded to form the hemispheres. He says that he has traced the fibres of 
 the peduncles as far as the median line of the corpus callosum, where those of one side 
 unite and are blended with those of the other ; but a careful examination of the cere- 
 brum, either by means of a stream of water, or by hardening it, shows that the fibres of 
 the corpus callosum terminate in the convolutions, without presenting any sort of re 
 flection, or forming any median raphe. 
 
 12. The dissections of M. Foville seem to establish the continuity of the coi-pus callo- 
 sum both with the radiating fibres of the corpora striata and with the fibres of the hem- 
 ispheres. According to his dissections, which consist essentially in transverse vertical 
 sections, the radiating fibres of the optic thalami and corpora striata divide immediately 
 into three very distinct superimposed planes. 
 
 The^rsf or superior plane is reflected upward and then inward, so as to describe a 
 curve with its convexity turned outward, passes horizontally inward to form the corpus 
 callosum, and unites with the corresponding fibres of the opposite side. 
 
 The second or middle plane, the plane of the hemisphere, ascends parallel to the corpus 
 callosum up to the point where the fibres of that body are reflected inward ; it then con- 
 tinues in an almost vertical direction, and thus reaches the gray matter. 
 
 The third or inferior plane, much smaller than either of the preceding, is extremely 
 thin, and follows a very different course : immediately after emerging from the common 
 place of origin, it descends on the outer side of the corpus striatum, turns round its low- 
 er part, approaches the median line, and then mounts upward, in contact with the cor- 
 responding plane of the opposite side, through the middle of the ventricles, where the 
 two juxtaposed planes form the septum lucidum. 
 
 13. Is the fornix an antero-posterior commissure 1 In support of this opinion, I may 
 state, that I have seen the right half of the fornix atrophied in a case of destruction of 
 the convolutions corresponding to the tentorium cerebelli. 
 
 14. The anterior commissure (m, fig. 283), which was regarded by Willis as the com- 
 missure of the corpora striata, and by Reil as intended to connect the anterior convolu- 
 tions of the middle lobe and some convolutions situated at the bottom of the fissure of 
 Sylvius, belongs to the system of converging fibres, according to Gall, who describes 
 them as commencing in the gray matter of the convolutions. According to Tiedemann, 
 this commissure is a continuation of the cerebral peduncles, each of which, after having 
 traversed the corpora striata, expands in the corresponding hemispheres, and gives ofl' 
 several radiating fasciculi which incline forward and inward, are collected together into 
 a cord, and unite with those of the opposite side ; the anterior commissure, therefore 
 according to this view, is a bond of union between the radiating fibres of the cerebra 
 peduncles and those of the right and left middle lobes of the brain. Chaussier had al- 
 ready derived the fibres of this commissure from the cerebral peduncles. All that is 
 certainly known regarding it is, that the cord of which it consists passes through the an- 
 terior portion of each corpus striatum, and expands in the anterior and inferior convolu- 
 tions of the sphenoidal horn of the posterior [middle] lobes, behind the fissure of Sylvius. 
 
 15. The cornu ammonis is formed by the reflection of the lower part of the hemi- 
 sphere : the white laminae which cover it, the corpus fimbriatum along its border, and the 
 
 * The following is Reil's statement on this subject: ;' Both of these two systems of fibres spread out into 
 rays and meet each other ; the cerebral peduncles ascend from below, and eipand into the form of an invert- 
 ed cone ; the system of the corpus callosum, on the contrary, comes from above, and its fibres insinuate them 
 selves between the preceding ones (see g,fig. 284), and form, as it were, tlie lid of the cup." 
 
756 NEUROLOGY. 
 
 fornix, constitute but one system, which evidently belongs to the antero-postenor com- 
 missures. 
 
 16. Each convolution is composed of two precisely similar semi-convolutions ; the 
 two halves, which can be readily separated by a stream of water, may be decomposed 
 into a considerable number of striated lamellae, arranged like a fan, the margin of which 
 would correspond to the free border of the convolution, and the narrow end to the ad- 
 herent border ; these striated lamellae are separated from each other by vascular fila- 
 ments ; their number seems to vary in different subjects ; they seem, moreover, to be 
 altogether independent of each other. The stream of water detaches a corresponding 
 layer of gray matter with each white lamella. This layer of gray matter is also striated, 
 and appears to be composed of fibres implanted upon the white matter, as Mr. Herbert 
 Mayo has very clearly pointed out. 
 
 1 7. It follows, therefore, that in the convolutions, a lamellar striated arrangement suc- 
 ceeds to the fibrous or linear arrangement of the medullary centres and radiating fibres 
 of each hemisphere.* 
 
 These lamellae are evidently continuous with the radiating fibres of the corpus striatum 
 and optic thalamus. Still, there is in each convolution a proper lamella, the continuity 
 of which with the radiating system of the hemispheres I have not been able to trace. 
 
 18. We should not regard the convolutions as so many sinuous eminences separated 
 by the anfractuosities : on the contrary, the bottom of the anfractuosity forms the mid- 
 dle part or fold of a layer of white and gray matter, half of which layer belongs to one 
 convolution and half to the next convolution (n n, fig. 284). Now it is these white lamel- 
 lae which line the gray matter that appear to be proper to each convolution ; and be- 
 tween these proper lamellae are situated the white striated plates that are continuous 
 with the radiating fibres of the hemispheres,t which fibres are not arranged in lamellae, 
 but merely in lines. 
 
 It follows from all that has been stated, that there are yet several deficiencies in our 
 knowledge of the anatomy of the brain, which prevent us from forming a complete idea 
 of its structure. 
 
 Development of the Cerebrum.^ 
 
 In the early periods of foetal life, about the end of the second month, the hemispheres 
 are represented by a very thin membrane, which is turned backward and inward, so as 
 to cover the corpora striata. 
 
 The optic thalami, which appear as enlargements of the cerebral peduncles, the tuber- 
 cula quadrigemina, and the cerebellum, are completely exposed. The corpus callosum 
 does not yet exist. The human brain may, then, be considered as resembling the brain 
 of fishes. 
 
 Towards the end of the third month, the membrane of the hemispheres has acquired 
 a farther development, and covers not only the corpora striata, but also the optic thalami. 
 The tubercula quadrigemina and the cerebellum are still exposed. The anterior lobes 
 only of the cerebrum are formed. The posterior lobes seem to be merely appendages. 
 The hemispheres, then, constitute at this period a membranous sac, which is open on the 
 inner side and behind, and may be regarded as representing the brain of reptiles. The 
 
 * M. Leuret has been led to the same conclusion regarding the lamellar structure of the convolutions, by 
 studying the brain hardened by boiling it in a solution of salt. 
 
 t iVIr. Herbert Mayo (a series of engravings intended to illustrate the structure of the brain and spinal 
 cord in man, 1825), who has followed the example of Reil, in examining the brain with so much care after it 
 hjis been hardened in alcohol, admits the existence of three sorts of fibres in each convolution, viz., fibres 
 ■which pass from one convolution to the next (u Uyfig. 283), and also to more distinct convolutions ; fibres which 
 come from the commissures (s s p) ; and fibres derived from the spinal cord. According to this anatomist, the 
 fibres which pass from one convolution to another constitute tlje principal part of each convolution ; the othej 
 white fibres which form the centre of each convolution are derived partly from the commissures and partly 
 from the optic thalami and corpora striata. 
 
 According to him, the white fibres (/ q) which form the inferior layer of the cerebral peduncles radiate in 
 the substance of the cerebrum, and constitute its anterior and middle fibres. The fibres proceeding from the 
 optic thalami form the posterior cerebral fibres (y). There is, he affirms, one point in which the radiating 
 fibres evidently decussate with the fibres from tlie great commissure of the brain or corpus callosum (as at g, 
 fig. 284). The posterior radiating fibres do not present this decussation. 
 
 The two most remarkable fasciculi of communication between the convolutions are the following : that 
 which occupies the bottom of the fissure of Sylvius (I, fig. 283 ; m,fig. 284), and which unites the convolu- 
 tions of the anterior and posterior lobes ; and that ( p p,fig. 283 ; I, fig. 284) which runs above the corpus cal- 
 fosum, crossing at right angles the direction of its fibres, and connects the anterior and superior with the pos- 
 terior and inferior convolutions. 
 
 Rolando has not been so successful in his researches into the structure of the cerebrum as in his investiga- 
 tions into that of the cerebellum: the following are the results which he obtained by tearing the brain, and 
 by examining this organ in the foetus. According to him, the brain is composed of fibres arranged in layers in 
 tiie following order, proceeding from without inward: 1. A white layer reaching into the fissure of Sylvius, 
 and covered by gray matter ; 2. A layer from which the fibres of the external convolutions arise ; 3. A layer 
 which is formed by the fibres of the peduncles, and supplies the convolutions of the inner border of the hemi- 
 sphere ; 4. A plane which extends from the optic thalami to the parietes of the lateral ventricles, to form the 
 corpus callosum ; 5. A system of longitudinal fibres which form the convolutions situated upon the inner sur- 
 I'ace of the hemispheres ; 6. A system of medullary fibres which constitute the fornix and coniu ammonis ; 7, 
 Intermil and external corpora striata, to which must be added the antenor commissures, the perforated layer, 
 and the fasciculus of the external corpus geniculatum. X Vide Tiedemann (translated by M. Jourdan) 
 
COMPARATIVE ANATOMY OF THE CEREBRUM. ?ST 
 
 corpus callosum begins to appear under the form of a narrow commissure, which unites 
 the two hemispheres in front, they being completely separated behind. 
 
 In the fourth and fifth months, the cerebrum covers the anterior part of the tubercula 
 quadrigemina. The posterior lobe exists, the fissure of Sylvius, which is well-marked, 
 separating it from the anterior lobe. We observe here and there some small depres- 
 sions, the traces of anfractuosities. The olfactory nerves, which are very large, and are 
 said to have been found hollow, as in the lower animals, appear to arise from the Sylvian 
 fissure. The corpus callosum is still very small, so that the optic thalami and the third 
 ventricle are exposed. At this period the human brain has some analogy with that of 
 the rodentia. 
 
 In the sixth month, the cerebrum covers the tubercula quadrigemina and the greater 
 part of the cerebellum. The only traces of convolutions are found upon the internal 
 surface of the hemispheres. The corpus callosum is prolonged backward with the hem- 
 ispheres, and from being vertical, now becomes horizontal. 
 
 At the seventh month, the corpora albicantia, which had hitherto formed a single mass, 
 as in the lower animals, become separated. The convolutions are defined, and the cere- 
 brum projects behind the cerebellum. 
 
 The changes occurring in the eighth and ninth months appear to be the development 
 of the convolutions and the perfection of the other parts of the brain. At this period 
 the characters of the human brain are well-defined. It may not be impossible, perhaps, to 
 recognise, in the rapid phases of this development, the characters of the brain in the 
 different orders of mammalia, but it is necessary to observe greater caution in admit- 
 ting these analogies than has been evinced by various naturalists. 
 
 As the corpus callosum continues to be developed backward, it ends by reaching the 
 anterior tubercula quadrigemina. 
 
 The corpora striata do not exhibit their white, radiating fibres until near birth, or soon 
 after it. The originating fasciculi of the fornix are not seen in the interior of the optic 
 thalami until the latter months of intra-uterine life ; and until then, also, the transverse 
 commissures and the white fibres of the optic commissure do not appear.* 
 
 The lateral ventricles are formed by the turning backward and inward of the membrane 
 which constitutes the hemispheres. And as this membrane is very thin until the end of 
 the third month, it follows that at this period the lateral ventricles are proportionally much 
 larger than they are afterward. The anterior cornua of these ventricles are developed 
 before the descending cornua, and these before the posterior cornua. During all this pe- 
 riod, the anterior cornua communicate with the cavities in the olfactory nerves. At the 
 sixth month, the lateral ventricles are completely closed. The choroid plexuses, which 
 exist in all animals provided with lateral ventricles, begin to appear as soon as these 
 cavities. 
 
 The distinction between the gray and white matter does not become evident until af- 
 ter birth. Tiedemann is of opinion that the formation of the gray matter takes place 
 after that of the white. This appears to me a pure hypothesis. The two substances are 
 formed at the same time ; but, properly speaking, they are neither white nor gray, and 
 they do not acquire their distinctive characters until some little time afterward. 
 
 Comparative Anatomy of the Cerebrum. 
 
 The Optic Thalami and Corpora Striata. 
 
 In analyzing the brains of the lower animals, it is of the utmost importance clearly to 
 distinguish the hemispheres, properly so called, from the optic thalami and corpora striata. 
 
 The optic thalami are recognised by their having a ventricle (the third) between them, 
 by being connected by an anterior and a posterior commissure, and, moreover, by being 
 continuous with the cerebral peduncles. 
 
 The size of the optic thalami is always proportioned to that of the hemispheres. In 
 fishes, the cerebrum appears to be almost entirely formed by the optic thalami. 
 
 There are no traces of corpora striata in fishes. Their existence in reptiles cannot 
 be doubted. They are of enormous size in birds, in which they constitute almost the 
 entire hemispheres. If it be true that, in the animal series, the size of the hemispheres 
 is always directly proportioned to that of the optic thalami, such is not the case with the 
 corpora striata, which, as I have already stated, are a kind of internal convolutions, and 
 are often inversely proportioned, in size, to the hemispheres, properly so called. 
 
 Thus, the corpora striata are very large in proportion to the hemispheres in the ro- 
 dentia : in this respect, as in many others, the brain of this order of mammalia approach- 
 es very near to that of birds. In the higher orders of mammalia, as the carniyora and 
 quadrumana, the proportion between the corpora striata and the hemispheres is neariy 
 the same as in the human subject. 
 
 * [Tiedemann describes fibres as distinctly appearing- in the corpus striatum in the sixth month, though 
 not so abundantly as afterward. He recog:nised'the anterior and posterior commissures before the end of the 
 third month ; at the same time, also, the anterior pillars of the fornix rising- from the united mass of the cor- 
 pora albicantia ; the fasciculi from the thalami to the corpora albicantia were quite distinct in the fifth month, 
 and could be recognised even somewhat earlier.] 
 
758 NEUROLOGY. 
 
 The Cerebral Hemispheres and Olfactory Lobes. 
 
 In Mammalia. —Man surpasses all the mammalia in regard to the size of the cerebral 
 hemispheres and the number of their convolutions. 
 
 The quadrumana stand next to man. The dolphin, perhaps, exceeds the ape in both 
 respects, and this would tend to support the relations of travellers respecting the won- 
 derful intelUgence of this cetaceous animal. 
 
 In the carnivora and ruminantia the hemispheres are smaller, the occipital lobe of the 
 cerebrum does not exist, and the anterior part only of the cerebellum is covered. There 
 is no fissure of Sylvius, and no lobe of the corpus striatum. In all these animals, the 
 number of the convolutions and the depth of the anfractuosities have appeared to me 
 to be as great as they are in man, in proportion to the size of the hemispheres. I have 
 not observed that regularity of the convolutions which several anatomists have pointed 
 out as contrasting with their irregularity in man. 
 
 The lowest order of mammalia, namely, the rodentia, have the letist complicated brain. 
 It is shaped like the heart on playing cards, almost resembling the brain of birds. The 
 cerebellum is completely exposed, and the tubercula quadrigemina are but partially cov- 
 ered by the cerebrum. There are scarcely any traces of convolutions, and the hemi- 
 spheres are reduced to a membrane folded upon itself 
 
 The corpus callosum is extremely small, but the cornu ammonis is very large. These 
 two parts seem to be developed inversely to each other. Thus, the corpus callosum is 
 larger and the cornu ammonis is smaller in man than in the lower animals. 
 
 In the rodentia, the gray matter of the convolutions is reflected beneath the fornix.* 
 
 In all mammalia, excepting the dolphin, the olfactory nerves, which are so delicate in 
 man, form two thick pedicles lying under the anterior lobes of the cerebrum, and termi- 
 nating in front by large ovoid bulbs, corresponding in size to that of the ethmoidal fossae ; 
 these enlargements are named olfactory lobes. They are continuous with the innermost 
 convolutions of the sphenoidal horn of the posterior lobe, which presents, above and be- 
 low, certain white fibres or striae, that are continuous with the cerebral peduncles. 
 
 The olfactory lobes have no relation with the corpora striata, as Cuvier was the first 
 to observe. In the dolphin, as in man, the corpora striata are very much developed. 
 
 The development of the olfactory lobe is inversely proportioned to that of the cornu 
 ammonis. 
 
 In Birds. — The cerebral hemispheres in birds are shaped like a heart on playing cards, 
 as in the rodentia ; there are no lobes and no convolutions, excepting a very superficial 
 longitudinal furrow, situated on each side of the median line. The brain almost entire- 
 ly consists of the corpora striata. The hemisphere is formed by a very thin gray lamina, 
 upon which are observed certain white radiated fibres. This lamina commences at the 
 inner part of the corpus striatum, turns outward round that body, and is continued to the 
 upper part. The interval between this lamina and the corpus striatum forms the lateral 
 ventricle. There is no trace of the corpus callosum, but there is evidently an anterior 
 commissure, which expands in the corpora striata. 
 
 In all birds of prey, two medullary bands arise in front of the commissure of the optic 
 nerves, and, having reached the front of the hemispheres, are expanded to form the ol- 
 factory lobes. In the other tribes, as in the gallinaceae, there are no olfactory lobes, but 
 certain small cords, which are merely the tapered extremities of the hemispheres. 
 
 In Reptiles. — The hemispheres are larger in the chelonians (tortoise) than in birds, 
 though they are very similar in many respects : as in birds, there are no olfactory lobes, 
 but merely two bands. In the saurians (crocodile, lizard) the olfactory lobe is continued 
 into the tapering point of the cerebral lobe by a very long pedicle. The batrachians and 
 ophidians have olfactory lobes in front of the hemispheres, from which they are separa- 
 ted by a circular constriction. 
 
 In Fishes. — Like reptiles, fishes have sometimes a single pair, sometimes two pairs 
 of lobes in front of the optic lobes. When there is only one pair, it must not be conclu- 
 ded that they represent the cerebral hemispheres ; if that pair is continuous with the ol- 
 factory nerves, they constitute the olfactory lobes. Whenever there is a pair of lobes 
 between the olfactory and the optic lobes, such pair belongs to the hemispheres. 
 
 The olfactory lobes and the cerebral hemispheres are so independent of each other, 
 tliat they are often inversely proportioned in regard to size, so that the cerebral hemi 
 spheres are larger in man than in any of the lower animals, while the olfactory lobes are 
 smaller. On the other hand, the olfactory lobes are the most highly developed in the 
 ray ; they are united together, are hollowed in the centre, grooved on the surface, ac- 
 cording to the observation of Vicq d'Azyr, and present some traces of convolutions. 
 Now, in the ray, there are no cerebral hemispheres, at least, unless we agree with Tiede- 
 mann in regarding the olfactory lobes as anologous to the corpora striata. In some fish- 
 es the olfactory lobe is supported by a pedicle of variable length. As to the cerebral 
 hemisphere, it is a mere tubercle, which appears to represent the optic thalamus. 
 
 * [Mr. Owen has discovered that the brain of marsupial animals resembles that of birds, in wanting the cor- 
 pus callosum (see his Memoir in Phil. Trans., 1837).] 
 
THE NERVES. 7S6 
 
 The corpus callosum, the fornix, and the septum lucidum do not exist either in birds, 
 reptiles, or fishes. 
 
 The corpora albicantia, which are wanting in birds and reptiles, are of enormous size 
 in fishes, and constitute a true lobe, according to Vicq d'Azyr and Arsaky. 
 
 The encephalon of fishes presents five pairs of lobes, which are, proceeding from be- 
 hind forward, 1. The lobes of the pneumogastric nerve, or lobe of the medulla oblongata ; 
 2. The cerebellum ; 3. The optic lobes ; 4. The cerebral hemispheres ; 5. The olfactory 
 lobes. 
 
 If we now generalize, with M. de Blainville, the notions'we have formed respecting 
 the encephalon of vertebrate animals, we may regard the different pairs of lobes of the 
 encephalon as so many pairs of ganglia situated upon the prolongation of the spinal cord ; 
 these he names ganglions saris appareil exterieur. The first or the most anterior pair 
 consists of the olfactory lobes, which are rudimentary in man. The second is the cere- 
 brum, properly so called. The third is formed by the tubercula quadrigemina or optic 
 lobes, which are rudimentary in man. The fourth is the cerebellum. The gangha 
 which constiJ;ute each pair communicate with each other ; each gangUon communicates 
 with that which precedes and that which follows it • and, lastly, they all communicate 
 with the spinal cord.* 
 
 THE NERVES, OR THE PERIPHERAL PORTION OF THE NERVOUS 
 
 SYSTEM. 
 
 General Remarks. — History and Classification. — Origin, or Central Extremity. — DiffererU 
 Kinds. — Course, Plexuses, and Anastomoses. — Direction, Relations, and Mode of Divis- 
 ion. — Termination. — Nervous Ganglia, and the Great Sympathetic System. — Conneximu 
 of the Ganglia with each other, and with the Spinal Nerves. — Structure of Nerves. — Struc 
 ture of Ganglia. — Preparation of Nerves. 
 
 General Remarks. 
 
 The nerves, which are concerned in the transmission of sensations and of motor influ- 
 ence, are white cords, attached to the cerebro-spinal axis by one extremity (the central 
 extremity), and distributed to the different organs by the other, or peripheral extremity. 
 They have a pearly-white aspect, like the tendons, with which they were for some time 
 confounded. Their surface is smooth, and presents a number of folds or zigzag marks, 
 which are effaced by extension.! Lastly, if a nerve be cut across, it is seen to be com- 
 posed of a certain number of cords, the divided ends of which project beyond the cut 
 surface. By these characters it will always be easy to distinguish a nerve from any 
 other white tissue in the body. 
 
 All the nerves are arranged in pairs : they differ from each other in their point of 
 junction with the central portion of the nervoiis system ; in their consistence ; in the 
 place at which they emerge from the cranio-vertebral cavity ; in their distribution ; and 
 in their functions. These points of difference have served as the foundations of the dif- 
 ferent classifications of the nerves proposed at various periods. 
 
 History and Classification of the JSTerves. 
 The nerves, which had been at first confounded with the tendons and ligaments under 
 the name of white tissues, were distinguished from those parts by Herophilus and Galen. 
 The subdivision of the nerves into the cerebral or cranial nerves, which pass out of the 
 foramina in the base of the scull, and the spinal or rachidian nerves, which emerge from 
 the inter- vertebral foramina, was so natural, that it suggested itself to the earliest anat- 
 omists who directed their attention to this system. The cranial nerves alone have pre- 
 sented some difficulties in their study and their classification. Marinus, whose work 
 has been long regarded £is classical, admitted only seven pairs of cranial nerves, among 
 which neither the olfactory nor the pathetic were included. Achillini was the first who 
 described the latter as a special nerve ; and it was Massa who classed the olfactory rib- 
 and among the nerves. Willis divided the cranial nerves (and his division is still adopt- 
 ed) into ten pairs, including the sub-occipital nerve. He also, like his predecessors, ad- 
 mitted thirty pairs of spinal nerves, and regarded the great sympathetic as forming the 
 forty-first pair. According to Willis, the olfactory nerves form the first cranial pair ; 
 the optic nerves, the second ; the common motor nerves of the eyes, the third ; the pa- 
 thetic nerves, the fourth ; the trigeminal nerves, the fifth ; the external motor nerves, 
 the sixth ; the facial and auditory nerves together, the seventh ; the pneumogastric, 
 glosso-pharyngeal, and spinal accessory, the eighth ; the hypoglossal nerves, the ninth ; 
 and the sub-occipital nerves, the tenth. This last pair, which was with so much reason 
 
 * [There is still considerable uncertainty as to the parts of the encephalon which correspond iu the higher 
 and lower vertebrata. For farther information on this point, as well as on the comparative anatomy of the 
 brain generally, see Leuret, Anatomic Comparee du Systime Nervevus, Paris, 1839.] 
 
 \ [These zig^zag folds led some anatomists to believe that the nerves have a sinuous arrangement. Monro 
 has even commemorated this anatomical error by a figure. The sinuous appearance common to the nerve* 
 and tendons disappears in both by stretching.] 
 
760 NEUROLOGY. 
 
 classed by Haller among the spinal nerves, has been alternately and arbitrarily removed 
 from one to the other class of nerves. Soemmering divided the seventh pair of Wilhs 
 into two distinct pairs : the seventh, or the facial nerves ; and the eighth, or the audi- 
 tory nerves : he subdivided the eighth pair of Willis into three pairs, namely, the ninth, 
 or the glosso-pharyngeal ; the tenth, or the pneumogastric ; and the eleventh, or the 
 spinal accessory nerves of Willis. But Soemmering's modification, as well as Mala- 
 carne's, who admitted fifteen pairs of cranial nerves, and also Paletta's, who described 
 as a particular nerve that branch of the fifth pair which is distributed to the temporal 
 and buccinator muscles, appear to me to be faulty, because they cause a confusion of 
 ideas without leading to any advantage. We shall, therefore, adhere to the classifica- 
 tion of Willis, which is most generally adopted. Nevertheless, with Vicq d'Azyr, we 
 shall prefer a nomenclature founded upon the distribution of the nerves to one which is 
 purely numerical. 
 
 Willis conceived the grand idea of separating the nerves of voluntary from those of 
 involuntary motion. Bichat seized upon this idea, which had already been rendered 
 fruitful by Winslow and Reil ; he unfolded it even to the minutest details, and appropri- 
 ated to himself, in some measure, the distinction of the nerves into those of organic and 
 those of animal life. The cerebro-spinal nerves constitute the nervous system of ani- 
 mal life ; the great sympathetic nerve fonns by itself the nervous system of organic life. 
 This last-named nerve consists of a series of gangha, or small nervous centres, distinct 
 from each other and from the brain. Bichat, moreover, anticipating all the importance 
 of the origin of the nerves, endeavoured to class them, not according to the points at 
 which they emerged from the cranium, but according to their origin, viz., into the nerves 
 of the cerebrum, which are ten in number ; the nerves of the pons Varolii, six in num- 
 ber ; and the nerves of the spinal marrow, thirty-four in number ; the only disadvantage 
 of this classification consists in its having been premature. 
 
 Other less important, and, in general, rather physiological than anatomical subdivis- 
 ions of the nerves, have been established. Thus, in reference to their consistence, the 
 nerves have been divided into the hard, which are motor nerves, and the soft, which 
 are sensory ; the former are said to come from the spinal cord, the latter from the brain. 
 The old distinction of the nerves into nerves of sc?isatimi and nerves of motion has been 
 lately revived ; and we shall have occasion to recur to it, as well as to Sir Charles Bell's 
 classification of the nerves into the symmetrical or primitive, and the superadded or respi- 
 ratory system. 
 
 The nerves might also be classified according to their size, but this mode of distinc- 
 tion would be completely useless. Every nerve presents for our consideration a central 
 oxtremity, a course, and a peripheral extremity. 
 
 The Central Extremity of the Jferves. 
 
 The central extremity of the nerves is that part by which they communicate or are 
 connected with the cerebro-spinal axis. It is generally called the origin of the nerves. 
 The use of such metaphorical expressions as origin, production, and efflorescence, has 
 not been without disadvantage to science ; for by the majority of anatomists they are 
 employed not in a figurative, but in a literal sense.* 
 
 The examination of the central extremity of the nerves is, perhaps, the most impor- 
 tant part of their study, because the properties of the nerves depend in a great measure 
 upon their point of connexion with the central part of the nervous system. This point 
 is, in reference to each nerve, constant and invariable, not only in man, but throughout 
 the animal kingdom, so that its exact determination enables us to establish what are the 
 analogous parts of the encephalon in different species. * 
 
 Each nerve has an apparent and a real central extremity or origin. The apparent ori- 
 gin is the exact point at which the nerve is given off from the surface of the cerebro- 
 spinal axis ; but, as several nerves can be traced into the substance of the cerebro-spinal 
 axis to a variable depth, it is probable that all of them have a much deeper real origin. 
 The older anatomists proceeded on this supposition, when they described all the nerves 
 as originating from the cerebrum, and more particularly from the corpus callosum, or, 
 rather, from the optic thalami and corpora striata. We are still ignorant of any central 
 point, or sensorium commune, forming the point of termination or of origin to all the nerves 
 of the body, 
 
 In respect of their origin, we might regard all the nerves as proceeding from the spi- 
 nal cord : the nerves of the face, and those of the organs of respiration and deglutition, 
 arise from the medulla oblongata and its cranial prolongations ; the nerves of the upper 
 extremity proceed from the cervico-dorsal enlargement of the cord ; and the nerves of 
 the lower extremity from the lumbar enlargement : the nerves of the trunk arise from 
 the spinal cord, between its three enlargements. The optic and olfactory nerves alone 
 appear to form exceptions to this rule. 
 
 All the spinal nerves present the greatest uniformity in reference to their origin, 
 
 * Comparative anatomy, and the anatomy of the fcetus, prove the independent formation of the different 
 parts of the nervous system. 
 
DIFFEREIVT KINDS OF NERVES. 761 
 
 course, and termination. The arrangement of the cranial nerves, which appears at first 
 sight to be uninfluenced by the laws which regulate the distribution of the spinal nerves, 
 may yet be referred to those laws to a certain extent, notwithstanding its apparent ir- 
 regularity and complexity. 
 
 The general remarks wiiich follow apply more particularly to the spinal nerves. 
 
 The spinal nerves arise by two sets of roots, the anterior (a, fig. 267) and the poste- 
 rior (b). 
 
 Gall advanced the notion that the posterior roots of the spinal nerves preside over ex- 
 tension, and the anterior roots over flexion of the trunk and limbs, and he explained the 
 predominance of extension over flexion by the greater size of the former roots.* Al- 
 though the fact of this predominance appears to me indisputable, Gall's explanation is 
 nevertheless rendered void, for it supposes a separation of the fibres of the anterior and 
 posterior roots in reference to their distribution, and no such a separation exists. 
 
 Sir Charles Bell, having proved by experiments that the facial nerve and the fifth 
 cerebral nerve had different properties, the former being devoted to motion and the lat- 
 ter to sensation, was led to examine whether there did not exist something analogous 
 in the other parts of the body ; and the double roots of the spinal nerves must have natural- 
 ly suggested themselves to his mind. Might not the object of this double origin be to 
 concentrate a double property in each pair of nerves 1 Experiments were instituted, 
 and they confirmed the preconceived ideas of this ingenious physiologist. They were 
 soon followed by the perfectly confirmatory experiments made by Magendie, who, by also 
 adducing facts in pathological anatomy, threw so much light upon this subject, that most 
 modern physiologists have admitted that the posterior roots belong to sensation, and the 
 anterior to motion. 
 
 Now, notwithstanding the imposing authorities which I have quoted, I must say that 
 I am by no means convinced of the reality of this distinction, and that, in repeating both 
 Bell's and Magendie's experiments, the section of the anterior and that of the posterior 
 roots appeared to me to produce precisely the same effects. + 
 
 I have also endeavoured to determine the question anatomically. 
 
 Some anatomists have thought that, after emerging from the ganglion, the filaments 
 from the two roots become so intimately mingled that the smallest nervous cord would 
 contain filaments from both the anterior and the posterior roots ; as far as I have been 
 able to ascertain, the filaments are interlaced, but never enter into a regular combination. 
 Again, in order to render the dissection more easy and conclusive, having macerated a 
 portion of a body in water containing nitric acid, and having tlius destroyed the neuri- 
 lemma or fibrous covering of the nerves, I endeavoured to trace some nervous filaments, 
 both cutaneous and muscular, to their origin ; but I never could succeed in this, so nu- 
 merous are the combinations into which tlie filaments enter. However, having directed 
 my attention more particularly to certain filaments given off from the cervical nerves to 
 be distributed to the scaleni muscles, I succeeded in tracing them into the correspond- 
 ing spinal gangli. Now the filaments which proceed directly from the spinal ganglia are, 
 according to the theory just alluded to, exclusively connected with sensation, and, con- 
 sequently, should not be distributed to the muscles. 
 
 The question of the anterior and posterior roots is connected with another more gen- 
 eral question, viz.. Are there different kinds of nerves 1 
 
 Different Kinds of JVerves. 
 
 The natural distinction of the nerves into those of sensation and of motion dates as 
 far back as Erasistratus, who described the sensory nerves as arising from the meninges, 
 and the motor from the cerebrum and cerebellum. This opinion was often revived and 
 always abandoned, and it was only when direct experiment appeared to confirm the an- 
 ticipations of theory that it became generally adopted. 
 
 Bichat, after the example of Winslow and Reil, divided the nervous system into two 
 grcErt sections, one of which belongs to animal and the other to organic life. The spinal 
 cord and encephalon form the common centre of the nervous system of animal life ; the 
 organs of the senses and the muscles are under its influence. All the organs supplied 
 by it are subject to volition and consciousness. The nervous system of organic life is 
 formed by the ganglia of the great sympathetic, which Bichat agrees with Winslow in 
 regarding as so many little brains. The organs of digestion, respiration, circulation, 
 and secretion are under its influence. All of the organs which it supplies are withdrawal 
 from the control of the will and of consciousness. 
 
 The subdivision adopted by Reil and Bichat prevailed in the science until Sir Charles 
 Bell was led back to the opinion of the ancients by some highly interesting*observations 
 and experiments ; he associated with that opinion the ideas of Bichat, and also estab- 
 
 * In this matter Gall has caufjht sight of a truth which I believe I have established upon incontestable evi 
 dencc, in describing the apparatus of locomotion ; namely, that in all parts of the body, excepting in the mus- 
 cles of the fingers, the extensors are more powerful than the flexors. 
 
 t [The accuracy of the experiments has now been amply confirmed ; and there is no doubt that the ante- 
 rior are the motor, and the posterior the sensory roots : no difference of structure has been detected between 
 tbem.J 
 
 5 1) 
 
762 NEUROLOGY. 
 
 lished an entirely new class of nerves, wliicli he named nerves of expression or respiratory 
 nerves. According to this view, there are five kinds of nerves : nerves intended for special 
 sensations, as the nerves of smell, of vision, and of hearing ; nerves of common sensation; 
 nerves of volwntari/ motion ; nerves of the respiratory movements ; and sympathetic nerves, 
 which appear to unite the body into a whole in relation to its nutrition, its growth, and 
 its decay. By a still wider generalization. Sir Charles Bell admits two systems of 
 nerves, viz., the the primitive or symmetrical nerves, which exist in all animals, and by 
 the aid of which they feel and move ; and, secondly, the superadded, irregular, or respi- 
 ratory nerves, the number of which is proportioned to the perfection of the general organ- 
 ization. It is the latter system of nerves that regulates the partly voluntary and partly 
 involuntary act of respiration, and also the several movements connected with it, such 
 as those of speaking, laughing, sighing, and sneezing. According to Bell, these nerves 
 arise from a special tract in the cord, and sometimes proceed separately or distinct from 
 he other nerves, and are sometimes blended with them, this occurring in such a man- 
 ner that neither their union nor their separation in any way impedes their functions. 
 
 This theory of superadded or respiratory nerves is very ingenious, but altogether hy- 
 pothetical. Besides, it is only strictly applicable to the case of four nerves, viz., the 
 pneumogastric, the glosso-pharyngeal, the spinal-accessory, and the facial. Sir C. Bell'a 
 opinion concerning the existence of a column situated between the anterior and poste- 
 rior roots of the nerves, along the whole extent of the spinal cord, and giving origin to 
 certain filaments which combine with those coming from the two roots so as to cause 
 them to participate in the great phenomenon of respiration, is quite gratuitous. 
 
 On endeavouring to decide whether there are several kinds of nerves, by anatomical 
 investigation, it is found that, excepting the olfactory, optic, and acoustic nerves, which 
 have altogether a peculiar arrangement, and the ganglionic nerves, which are generally 
 grayer and more slender, there is no difference in the character and structure of the 
 nerves of different parts of the body. The cutaneous nervous filaments are exactly sim- 
 ilar to the muscular nervous filaments. 
 
 From the law of organization, that identity of structure is always connected with iden- 
 tity of function, I have been led to admit that the nerves are homogeneous ; that the dif- 
 ferent properties attributed to them belong to the organs to which they are distributed ; 
 and that they perform no other office in the economy than that of conductors — conductors of 
 sensation when they are distributed to a sensory organ, and conductors of motor influence 
 when they enter a motor organ.* This view of the homogeneous structure of the nerves 
 explains much more readily than the opposite one all the phenomena of innervation, 
 and, in particular, the unity of all parts of the nervous system. 
 
 Moreover, if we admit the existence of special nerves to preside over some special 
 phenomena, and to be distributed to particular organs, why not admit them for all special 
 actions and for all organs 1 There would then have to be digestive nerves, generative 
 nerves, and secreting nerves of different kinds. 
 
 Course^ Plexuses, and Anastomoses of the JVerves. 
 
 The course of the nerves must be examined both while they are within and while they 
 are outside the cranio-vertebral cavity. Within this cavity the extent of their course 
 is variable ; and their distribution, after they have emerged from it, is more or less com- 
 plicated. All, or nearly all, the cerebro-spinal nerves communicate with the great sym- 
 pathetic system. When the parts to which they are destined are not complicated, their 
 distribution is very simple, as, for example, the nerves of the thoracic and abdominal 
 parietes ; but when those parts are complicated, the arrangement of the nerves is pro- 
 portionally intricate ; and they then unite so as to form certain interlacements called 
 plexuses, as, for example, the thoracic and abdominal plexuses. 
 
 The nervous plexuses, which Bichat regarded as so many centres in which the branch- 
 es of origin of the nerves ended, and from which their terminal branches commen 
 ced, are Ibrmed by the division and subdivision of a certain number of nerves, wnich 
 enter into new combinations, and form an almost inextricable interlacement. 
 
 Within these plexuses there is generally so intimate a combination of the different 
 elements of which they are composed, that it is almost impossible to determine exactly 
 what branches of origin are concerned in the formation of any particular terminal branch. 
 A branch of a nerve issuing from a plexus belongs, therefore, to all the nerves which en- 
 ter into the composition of that plexus. 
 
 The plexuses do not consist of actual anastomoses of the nervous cords ; nor do they, 
 as Monro believed, contain any gray matter : they do not afford origin to any new ner- 
 vous frlamenfs, but they merely give off those which they have received. The most 
 careful examination reveals nothing more than an interchange of nervous cords, which, 
 although they enter into new combinations, still remain independent of each other. 
 
 * The homogeneous structure of the different nerves is proved by the anatomical fact, that the same nerv« 
 is distributed to a great number of organs having very diiferent functions, as, for example, the eighth pair; 
 and also by a fact in comparative anatomy, namely, that the same pair of nerves may, in. different species, pre- 
 side over totally different functions ; for example, the fifth pair. 
 
DIRECTION OF THE NERVES. 763 
 
 The term nervous anastomoses is applied to the communications by loops, or at more 
 or less acute angles, which take place between the nervous filaments. The older anat- 
 omists, governed by the idea that there existed a fluid circulating in the nerves, sup- 
 posed that in the anastomoses of nerves there was a mixture of nervous fluids, nearly 
 similar to that which takes place in vascular anastomoses, where two different columns 
 of blood are intermixed. They regarded the nervous anastomoses as the most active 
 source of sympathies. Bichat also admits the existence of these anastomoses, in which, 
 he says, there is not only a contiguity, but also a continuity of nervous filaments. Be- 
 clard* defends the use of the term anastomosis, and endeavours to define its meaning 
 thus : " There is not merely an application of nervous filaments in the anastomoses, but 
 a true communication, a junction {abouchement) of their canals, which, in truth, contain a 
 fixed substance, not a circulating fluid, as was formerly believed." 
 
 But, on examining the structure of the nervous anastomoses, it is seen that there is 
 simply a juxtaposition of filaments derived from two different sources. The examina- 
 tion also proves most distinctly that the anastomoses are merely small plexuses, so that 
 the only difference between them is, that in the -plexuses there is an interchange of nervous 
 cords, while in the anastomoses there is an interchange of nervous filaments or of primitive 
 fibres. The anastomoses, like the plexuses, are intended to concentrate the action of 
 several nerves upon any given point, as on a centre, from which their action may ex- 
 tend to certain parts necessarily connected in function. 
 
 The nervous loops described by Bichat upon all points of the median line of the body, 
 and by the existence of which he supposed that he could explain the return of sensation 
 and voluntary motion to paralytic parts of the body, do not exist. The only anastomoses 
 in the middle line with which I am acquainted are those of the two pneumogastric nerves 
 behind the lower extremity of the trachea, that of the two solar plexuses, and that of 
 the cardiac nerves. 
 
 The Direction, Relations, and Mode of Division of the Jferves. 
 
 The nerves are very deeply situated at their egress from the cranio-vertebral cavity. 
 Thus, the brachial plexus is protected by the osseous girdle of the shoulders, and the 
 sacral plexus by the pelvic bones. The nerves then pass into the great cellular inter- 
 vals, which we have already described as existing in the limbs for the reception of the 
 principal vessels and nerves, and for the preservation of those parts from pressure. 
 
 The direction of the nerves is generally straight, and their length corresponds exact- 
 ly with the distance from their point of origin to that of their termination, so that, if the 
 movements of the hmbs exceed their ordinary extent, the nerves may suffer severe in- 
 jury by being stretched. This straight direction is, in general, an essential character of 
 a nerve. Nevertheless, a considerable number of nerves deviate from their primitive 
 direction,! so as to describe a portion of a circle, or are seen reflected upon themselves 
 in a direction precisely opposite to their original one. Others describe a zigzag course, 
 like the arteries ; but these flexuosities are effaced in certain positions of the body, or 
 during the distension of particular organs. 
 
 Although there is but one arterial trunk for each limb, there are always several nerves, 
 the number of these being variable. As the arteries often deviate from their original 
 direction, they describe certain turns, so as to occupy alternately the opposite sides of 
 a limb. Now, as the nerves pass in a straight direction, and the arteries describe cer- 
 tain curves, it follows that the same nerves cannot accompany the same arteries during 
 the whole of their course. Thus, when an artery deviates from its primitive direction, 
 it has two satellite nerves, one during the first, and the other during the second part of 
 its course. For instance, the crural nerve accompanies the femoral artery, and the 
 sciatic nerve the popliteal artery. When an artery bifurcates or otherwise divides, there 
 is often a particular nerve for each subdivision : thus, the median nerve is the satellite 
 of the brachial artery, the radial nerve accompanies the radial artery, and the ulnar nerve 
 the xdnar artery. 
 
 It follows, also, from what has been said, that the nerves have no accompanying ves- 
 sel for a more or less considerable portion of their course ; such is the case with the 
 great sciatic and the pneumogastric nerves. 
 
 The relations of the arteries with the nerves are constant, so that modem surgeons 
 attach great importance to these relations ; in fact, as a nerve, on account of its white- 
 ness, is more easily recognised than an artery, as soon as the former is exposed the 
 latter is immediately met with. It is important, moreover, to determine with the great- 
 est accuracy what nerves are contained witliin, and what nerves are situated without, 
 the sheath of their corresponding artery. Besides its principal nervous trunk, an artery 
 is also accompanied by certain nervous filaments, which are closely applied to the ves- 
 sels, which are very difficult to separate from it, and which often escape observation 
 
 * Anat. G6n6rale, p. 659. 
 
 t I do not think that a straight direction is necessary for the transmission of the nervous influence, for this 
 takes place in a lle.ve(J limb along a curved nerve, as well as in an extended limb along astraig'ht nerve , but 
 it is probable ihat it sliorteus the duration of this trausmission. 
 
764 NEUROLOGY. 
 
 from their tenuity. These are the filaments which render ligature of the arteries so 
 painful. 
 
 Division of the Nerves. — During their course, the nerves do not divide, like the vessels, 
 by ramifying into smaller and smaller branches ; but they give off in succession, as they 
 proceed, branches to the different parts through vehich they are passing, and thus be- 
 come gradually exhausted, until, reduced to mere filaments themselves, they terminate 
 in the same manner as their branches. The subdivision of nerves, therefore, docs not con- 
 sist in a ramification, but in a process of separation or emission. There is one circumstance 
 which has attracted the attention of all anatomists, viz., that the nerves do not diminish 
 in size in proportion to the number of filaments given off from them : some of them 
 even appear to increase in size after having given off several filaments. This apparent 
 singularity is explained, not by the fact that new filaments are added, but by the flatten- 
 ing of the nerve, the separation of its filaments, the addition of a certain quantity of adi- 
 pose tissue, or the thickening of the neurilemma. 
 
 Termination of JVerves. 
 
 The distribution of the nerves is perfectly determinate : each nerve, indeed, has its 
 own distinctly limited department ; an arrangement which, connected with what has al- 
 ready been said regarding the anastomoses, explains why the nerves cannot supply the 
 place of each other. When the principal arterial trunk of a limb is tied, the circulation 
 is re-established by the collateral vessels ; but when a nerve is cut across, all the parts 
 to which it is distributed are paralyzed. 
 
 The termination of the nerves is, undoubtedly, one of the most important points in 
 their anatomy. In the skin, the nerves terminate in the papillae, not one of which is 
 destitute of them ; in the muscles, they terminate in extremely delicate filaments, which 
 pursue a very long course in the substance of these organs, before they become invisible 
 to the naked eye or to the eye aided by a lens : it has appeared to me that each nervous 
 filament was so arranged as to be in contact with a very great number of muscular fibres, 
 situated either in the same or in different planes. 
 
 It is probable that there is not a single muscular fibre which is not thus lightly touched 
 by a nervous filament ; this anatomical fact may suggest, instead of Reil's ingenious 
 hypothesis of an atmosphere of activity around each nervous filament, the important 
 conclusion that the nerves act upon the muscular fibre by the effect of contact.* 
 
 MM. Prevost and Dumas believe that the nervous filaments terminate by loops in the 
 substance of muscles ; and upon their incomplete observations they have founded a theory 
 of muscular contraction. Nervous loops may certainly be observed in the substance of 
 the recti muscles, which they selected as examples ; but these loops are not the termina- 
 tion of the nerves, for a number of filaments are seen to issue from them, and to be dis- 
 tributed in the manner just pointed out.t 
 
 The different organs vary much in regard to the number of nerves which they receive ; 
 the organs of the senses — the eyes, the ears, the nasal fossae, the tongue, and the skin — 
 stand first in this respect. Next to these rank the muscles, which receive nerves in 
 proportion to the number of their fibres and to their activity. The organs of nutritive 
 life are far removed from the preceding in regard to the quantity of nerves distributed 
 to them. No proper nerves have yet been discovered in cellular tissue, serous mem- 
 branes, tendons, aponeuroses, and articular cartilages. All the articulations are provided 
 with nerves, called articular, which may be traced into the ligaments, and even upon the 
 synovial membranes. 
 
 The long bones, in addition to their central or medullary nerve, have certain periosteal 
 nerves which are lost in the periosteum, and also proper nerves of the spongy tissue, 
 which enter the foramina at the extremities of these bones. •'• 
 
 The Nervous Ganglia and the Great Sympathetic System. 
 
 The nervous ganglia are certain grayish knots or swellings situated along the course 
 of the nerves, and having a rather close resemblance to the lymphatic glands or ganglia. 
 Considered generally, the ganglia are a kind of nervous centres, towards which a certain 
 number of filaments converge, and from which they again pass out under new combina- 
 tions. Hence arose the ingenious idea of Winslow, who compared the ganglia to little 
 
 * This hypothesis of a nen-ous atmosphere was suggested to Reil by the theory of a nervous fluid, which he 
 regarded as analogous to and almost identical with the electric fluid ; and also by the fact that the nervous ap- 
 paratus is not able to supply filaments to all the muscular fibres. 
 
 t [The loops described l)y Provost and Dumas seem to have consisted of small nervous cords ; but Valentin, 
 Emmert, and Burdach have observed that the ultimate filaments (primitive fibres of MiiUcr) have a loop-like 
 termination iu the muscles. In reference to the nerves of sensation, it has been observed by Valentin and 
 Burdach, that in the frog's skin the primitive fibres end in loops ; this mode of termination has also been seen 
 by Schwann in the tail of the larva of the toad, and in the frog's mesentery. Schwann farther states, that in 
 both these cases the nervous fibres gave off exceedingly small fibrils, on which minute swellings (ganglia) were 
 placed, and which in some situations formed a network. In the papilla: of the human skin, Breschet thought 
 he saw the nerves ending in loops ; and Gherber believes that he has seen these terminal loops in the skin of 
 quadrupeds. Observers differ in their account of the mode of termination of the optic and auditory nerves <»«* 
 Organs of Sight and Heaking).] 
 
CONNEXIONS QF THE GANGLIA. 765 
 
 brains ; an idea which was revived under a modified form by Bichat, who made it the 
 basis of his admirable chapter upon the nervous system of organic hfe. 
 
 The nervous system of invertebrate animals is reduced to a series of ganglia and gan- 
 glionic nerves ; Swammerdam, Haller, and the older anatomists regarded this series of 
 ganglia as a spinal cord enlarged at intervals. But there is no point of comparison be- 
 tween these two parts ; in a word, the enlargements of the spinal cord and brain cannot 
 be likened in any respect to the ganglionic enlargements. 
 
 There are three series, or, as some say, three kinds of ganglia : viz., the spiTial or 
 rachidian ganglia ; the intercostal ganglia ; and the splanchnic ganglia ; these last are situ- 
 ated near the viscera for which they are intended. 
 
 The first series, or the spinal ganglia, belong to the organs of relation. They are con- 
 stant, regular, and symmetrical, like the nerves upon which they are placed. The other 
 two series are destined for the apparatus of nutritive life, and constitute the great sym- 
 pathetic system, improperly called the ganglionic system. 
 
 The identity in nature between the spinal ganglia and the ganglia of the great sympa- 
 thetic, and also between the cerebro-spinal and the ganglionic system of nerves, is de- 
 monstrated by the fact that in a great number of animals the ganglia are blended, or, as 
 it were, fused together. M. Weber {Anat. Comparee du Nerf Sympathique, 1817) has ob- 
 served, that in animals the development of the great sympathetic is always inversely pro- 
 portioned to that of the spinal cord. He has established a similar relation between the 
 great sympathetic and the pneumogastric nerve ; and, indeed, in certain species the latter 
 nerve entirely replaces the former. 
 
 The experiments of M. Legallois upon the spinal cord led him to admit that the vis- 
 ceral nerves are under the influence of the spinal cord, and that the roots of the great 
 sympathetic are in the cord. 
 
 There are as many spinal ganglia on each side as there are spinal nerves. The gan- 
 glia of the great sympathetic in the sacral, lumbar, and dorsal regions, are as numerous 
 as the spinal ganglia ; in the cervical region, there are only two or three sympathetic 
 ganglia to correspond to the eight spinal ganglia. The superior cervical ganglion may 
 be supposed to represent several ganglia. 
 
 In the cranium it is difficult to find any ganglia corresponding to the spinal ; still, the 
 Gasserian ganglion, and the ganglion of the eighth pair, may be regarded as analogous 
 to them. 
 
 On the other hand, we may regard the ophthalmic ganglion, the spheno-palatine or 
 Meckel's ganglion, the otic ganglion, and even the upper part of the superior cervical 
 ganglion, as forming the cranial ganglia of the sympathetic system. 
 
 Nevertheless, it would, perhaps, be more rational to regard the ophthalmic and otic 
 ganglia as quite independent of the three above-mentioned series of ganglia, and as con- 
 nected with certain local functions. There are a considerable number of these local 
 ganglia, which have received no particular names, and which I shall hereafter point out. 
 
 Connexions of the Ganglia with each other, and with the Cerebro-spinal 
 
 JSTerves. 
 
 The spinal ganglia belong specially to the posterior roots of the spinal nerves ; but it 
 will presently be seen that the anterior roots are not altogether unconnected with them. 
 
 From the spinal ganglia proceed three branches, viz., a middle branch, forming the 
 continuation of the spineil ners'e ; an anterior or ganglionic branch, proceeding to the cor- 
 responding ganglion of the great sympathetic ; and a posterior branch, which is distribu- 
 ted to the muscles and skin on the posterior region of the trunk. 
 
 Each of the ganglia of the great sympathetic receive one or several filaments from the 
 spinal ganglia, and also a connecting cord from the sympathetic ganglion immediately 
 above it ; and each of them gives off a connecting cord to the ganglion next below it, 
 and also certain visceral branches, which sometimes terminate directly in the viscera, 
 and sometunes, when their distribution is complicated, proceed to the splanchnic ganglia. 
 
 Not unfrequently the conmiunicating cords between some of the ganglia of the sym- 
 pathetic are wanting, and the continuity of this nerve is then interrupted. Bichat relies 
 chiefly upon this interruption in support of his opinion, that the great sympathetic is not 
 a nerve properly so called, but that each of its ganglia is the centre of a small special ner- 
 vous system, equally distinct from the cerebro-spinal system and from the other ganglia. 
 
 The splanchnic ganglia are the centres or points of convergence of a great number of 
 nerves, of which some are derived directly from the cerebro-spinal system, and others 
 from the ganglia of the great sympathetic. In those splanchnic ganglia which approach 
 the median line, the nerves of the right side become blended with those of the left by a 
 great number of plexiform branches, which have a ganglionic aspect, surround the vis- 
 ceral arteries, and are subdivided with them to enter the substance of the viscera. 
 
 It follows, then, from what has been just stated, that the great sympathetic is neither 
 a continuous nerve, differing from other nerves only by having enlargements, as was be- 
 lieved by the older anatomists, who described the right and left sympathetic as cnnsti- 
 
766 NEUROLOGY. 
 
 tuting a special pair ; nor is it, as Bichat conceived, a linear series of small nervous 
 centres or little brains, which give off in all directions connecting filaments, both to the 
 spinal and to the visceral nerves ; it is a series of ganglia connected with one another 
 in their action, and originating from each of the spinal nerves given off from the cerebro- 
 spinal axis. It does not arise from the sixth cerebral nerve, nor from the vidian or 
 carotid filaments, more than from any other spinal nerve ; but it takes its origin from 
 the whole spinal cord ; and if it does not diminish in size as it recedes from the brain, 
 but even increases at some points, this is because it receives new filaments of origin 
 during its course. 
 
 According to an ingenious hypothesis, which is fully confirmed by anatomical facts, 
 the viscera, which receive their nerves from the ganglia of the great sympathetic, derive 
 their principle of action from the whole spinal cord, so that an affection of one nerve, or 
 of one visceral ganglion, must affect the whole ganglionic system, in consequence of the 
 intimate connexions between all the ganglia ; and also the cerebro-spinal system, from 
 the connexions between the sympathetic ganglia and the spinal cord. It would follow 
 from this, that the sympathetic and the splanchnic ganglia together constitute one vast 
 plexus, which connects, in an intimate manner, the several viscera with each other and 
 with the rest of the body. This mutual dependance and sympathy is the chief charac- 
 teristic of the organs of nutritive life, that is to say, of the organs which receive their 
 nervous filaments from the splanchnic and sympathetic ganglia. 
 
 Structure of the JVerves. 
 
 Prochaska was the first to throw any light upon the obvious structure of the nervous 
 cords, and to prove that they consisted of true plexuses. Reil, not being contented with 
 noticing the plexiform arrangement of the nervous cords, endeavoured especially to de- 
 termine their structure ; and he failed only because he selected the optic nerve as the 
 type of the other nerves, whereas its structure happens to be exceptional. 
 
 Each nerve consists of a plexus enveloped in a common fibrous sheath. If this sheath 
 be opened, and the small nervous cords contained within it are spread out by tearing the 
 cellular tissue, it is found that these small cords, which at first seem to be parallel and 
 in juxtaposition, anastomose in a great number of ways, so as to form an extremely 
 complicated plexus. It is also seen that the cords are of unequal size, not only in the 
 same nerve, but also in different nerves ; they are smallest in the branches of the great 
 sympathetic and pneumogastric, and are largest in the nerves of the arm and in the great 
 sciatic nerves. 
 
 On spreading out a nerve, with its component cords separated from each other, upon 
 a plate of wax, and keeping those cords asunder by pins stuck at intervals, the absolute 
 impossibility of following them through their successive subdivisions, and the multiplicity 
 of their combinations, will become quite apparent. 
 
 The nerves consist essentially of two parts, viz., the nervous matter properly so called, 
 and its envelope oi fibrous sheath, which has been called the neurilemma. 
 
 There is a common neurilemma or common fibrous sheath for each nerve. Besides 
 this, each small nervous cord and each fibre is provided with a proper sheath or neuri- 
 lermna. The neurilemmatic canals divide, subdivide, and anastomose like the small 
 nervous cords themselves. 
 
 The neurilemmatic canals are composed of fibrous tissue : their shining aspect (which 
 has caused them to be frequently mistaken for tendons), their strength, their inextensi- 
 bility, their low degree of vitality, in fact, all their characters, clearly prove their fibrous 
 nature and exclusively protective function.* 
 
 The neurilemma of the nerves is continuous with the neurilemma of the spinal cord. 
 
 Nervous Matter. — If, as was shown by Reil, a nerve be immersed in diluted nitric acid. 
 Its neurilemma will be dissolved (rendered transparent), while its nervous matter will 
 become remarkably dense and opaque. We shall hereafter see how valuable is this 
 double property of acids in their action upon nerves for determining the true character 
 of fibres supposed to be nervous. In a nerve thus prepared, it is seen most clearly, that 
 the nervous filaments of which it is composed are continually anastomosing by loops or 
 at certain angles ; and that the addition of one set of filaments to the trunk of the nerve, 
 or the separation of others from it, necessarily interrupts the chain of their relations at 
 the very point where it seemed possible to ascertain them, so that, after every few inches, 
 the component parts of a nerve are completely changed. 
 
 What is the structure of the nervous matter 1 It is not a pulp, but is composed of 
 pencils of exceedingly fine filaments, which may be compared to the fibres of raw silk : 
 these filaments are parallel and in juxtaposition ; they are free throughout the whole 
 length of the nerve, and may be distinctly separated from each other ; when not stretched, 
 they are flexuous like a waved line. Each nervous filament reaches the entire length 
 of the nerve. In each nerve, the filaments of which the fibres are composed pass con- 
 
 * It may bo said that the neurilemma owes its fitness as a protecting organ as well to its low vitality as to 
 its strength. This low degree of vitality of the neurilemma is the cause why nerves are constantly seen oasn 
 ing through inflamed or degenerated parts without being aflTected themselves. 
 
STRUCTURE OF THE NERVES. 767 
 
 tinually from one fibre to another, and enter into an immense number of combinations, 
 without ever becoming blended together. 
 
 This structure, which is so evident in a nerve hardened by nitric acid, is not less dis- 
 tinct in nerves which have undergone no preparation.* On puncturing the neurilemma, 
 the nervous matter protrudes through the opening, precisely in the same way as the 
 substance of the spinal cord protrudes under similar circumstances. On dividing the 
 neurilemma along the whole length of the nerve, the nervous matter appears like long, 
 parallel filaments, of a milk-white colour, which float in water if the nerve be immersed 
 in that fluid. 
 
 Every nervous filament (and this is a fundamental point in their anatomy) has its 
 central extremity in the cerebro-spinal axis, and its peripheral extremity at its point of 
 termination. During the whole of its long course, it only enters into new combinations 
 without ever being interrupted. 
 
 Continuity is a law of the structure of the nervous filaments A 
 
 Can the nerves be injected 1 
 
 The doctrine of a nervous fluid, which so long prevailed in the schools, led physiolo- 
 gists to admit the existence of canals for the circulation of this fluid. Several experi- 
 mentahsts stated that they had collected the nervous fluid, and they even described its 
 properties ; and anatomists instituted no researches to confirm or refute these asser- 
 tions. Malpighi himself, who, in reference to the study of anatomy, carried to such an 
 extent that system of philosophical skepticism which has completely revolutionized all 
 science, believed that he saw the nervous fluid escape from the cut end of a nerve, like 
 a glutinous juice, which he compared to spirits of turpentine. t 
 
 Reil and some others have injected the neurilemma. Reil describes a very ingenious 
 method of injecting the optic nerve, which consists in opening the transparent cornea, 
 and injecting mercury into the globe of the eye : the mercury passes through the fora- 
 mina, which transmit the filaments of the optic nerve at the point where these become 
 continuous with the retina. 
 
 Such was the state of our knowledge when Bogros, prosector to the Faculty, having 
 accidentally punctured a nerve with the tube of a mercurial injecting apparatus, observ- 
 ed that the mercury ran along the punctured nervous fibre, and also into the adjacent 
 nervous fibres ; he repeated and varied his experiments in a great number of ways, and 
 soon published a memoir, in which he formally announced as a demonstrated fact that, 
 in each nervous fibre, there was a central caned capable of being injected ; and, in his 
 enthusiasm at his discovery, he thought that he had realized the desire of Ruysch,1: and 
 that he could henceforth trace the nerves to their very finest terminations. 
 
 The work of Bogros was in general received with little favour, and, I think, has not 
 been estimated at its real worth. Having renewed his experiments, I have arrived at 
 the following result : If, with a pair of blunt pincers, a nervous fibre be raised from the 
 centre of the nerve to which it belongs (from the middle of the median nerve, for exam- 
 ple), and if the tube of the lymphatic injecting apparatus be inserted accurately into its 
 centre, the mercury will be seen to run by jerks, either downward or upward, along the 
 centre of the nervous fibre, and to pass into a variable number of the adjacent fibres ; if 
 the injection be a successful one, the greater number of the fibres of the nerve will be 
 injected throughout their whole length. Gentle pressure with the finger, or with the 
 handle of the scalpel, greatly facilitates the progress of the mercury ; but it often hap- 
 pens that the parietes of the canal through which the mercury is passing yield at some 
 point, a rupture ensues, and the fluid is extravasated. 
 
 When the nervous fibre has not been punctured in the centre, the mercury is seen to 
 run along the injected fibre, and even into some of those near it ; but the mercurial col- 
 imin is never regular ; it does not occupy the centre of the fibre, but only one side of it ; 
 and it is soon extravasated into the neurilemmatic sheath, which in a short time bursts. 
 
 This second kind of injection, which may be made at wUl by puncturing the fibre su- 
 
 * I have also examined this structure in living animals, while endeavouring to determine the insensibility 
 of the neurilemma and the sensibility of the nervous filaments. 
 
 t [The nervous filaments (primitive fibres of MUUer) are simple tubes, containing a thread of a soft, semi- 
 transparent substance ; they are continuous with the white fibres of the brain and spinal cord at the apparent 
 origin of the nerves. The primitive fibres of the nerves resemble those of the brain and cord in the nature of 
 their contents, but they are larger, and their tubular, homogeneous sheath is much more distinct, and is firmer, 
 so that they do not become varicose. The olfactory, optic, and auditory nerves, however, are exceptions to 
 this rule ; their fibres resembling those of the brain and cord, in their size, delicacy, and liability to become 
 varicose. No differences have been observed between the fibres of the other cranial and spinal nerves, nor yet 
 between those of the motor and sensory roots. The sympathetic nerve, and all which receive fibres from it, 
 contain, besides the ordinary nervous fibres, a greater or less number of jointed fibres (gray fibres, MUUer ; 
 organic nervous fibres, Schmann ; cellular tissue, Valentin), exactly like those found in the ganglia and in the 
 gray matter of the brain and spinal cord.] 
 
 t But, as Haller remarks, Malpighi only saw this upon cutting through the Cauda equina, and never ob- 
 served it in the section of any other nerves ; now, it is extremely probable that he saw merely the serous fluid 
 which is most commonly found in the lower infondibuliform portion of the spinal dura mater : " Quam yehe- 
 menter suspicor eum clarum virum humorem vidisse viscidurn, quo infundibulum durie membrane spinalis fre- 
 ciuentissime plenum est, ct qui idem in spinam bifidam auctus aliit." — (Haller, Elem. Physiol., t. iv., p. 197.) 
 
 t) Ruysch sa.d that he should have nothing to desire if he could succeed in injecting the nerves as he had 
 done the vessels. 
 
768 NEUROLOGY. 
 
 perficially, differs essentially from the former one, obtained by introducing the pipe into 
 the centre of the fibre. In the latter case, the small column of mercury is uniform and 
 regular, and its metallic lustre is, as it were, observed ; the fluid runs rapidly ; the ner- 
 vous canal is less easily ruptured ; and, when this does happen, it is preceded by a pro- 
 trusion of the nervous matter ; then the mercury is extravasated into the neurilemmatic 
 sheath, and it pursues the same course as it would have taken if the nervous fibre had 
 been punctured superficially in the first instance. 
 
 Where do the injections pass in these two cases ■? In the second method, that is to 
 say, when the nerve is punctured superficially, it is the neurilemma that is injected. But 
 in the method of central injection, is the nervous matter itself injected 1 Bogros be- 
 lieved that it was, and he even asserted that he had seen a central canal with the naked 
 eye ; but no such canal exists ; and the one which he showed after desiccation of an in- 
 jected nerve was artificially made, as we shall immediately find. How, indeed, can we 
 admit the existence of a canal in nervous matter, which we have shown to consist of a 
 pencil of parallel and juxtaposed filaments'? 
 
 If, therefore, in the central injectiouj the mercury neither enters into the nervous mat- 
 ter, nor is contained in the neurilemma, where is it situated 1 Is it in lymphatic ves- 
 sels 1 We do not know; for lymphatics have not been shown by any one. Are they 
 arteries or nerves 1 To this it may be answered, that the bloodvessels do not follow the 
 direction of the nerves. 
 
 All this is explained by the following fact : each nervous fibre, besides its common 
 neurilemmatic sheath, has also a proper sheath, in contact with the neurilemma by its 
 outer surface, and with the bundle of nervous filaments by its inner surface, which is 
 smooth and moist. This sheath may be demonstrated by cutting a nerve across, and 
 seizing one of the tufts which project beyond the retracted neurilemma ; a nervous fibre 
 can then generally without effort be drawn out several inches, having a smooth surface, 
 and being completely freed from its common neurilemma. Now this fibre consists not 
 only of nervous matter, but also of a proper sheath perfectly distinct from the neurilem- 
 ma. It may now be injected, and will then present all the characters of the central in- 
 jection already mentioned ; and, upon examining it with a lens, it will be seen that the 
 nervous filaments of which it is composed are regularly distributed around the column 
 of mercury. 
 
 It follows, then, that, in the central injection of a nerve, it is neither the neurilemma, 
 nor the nervous matter, nor the vessels that are injected, but the proper sheath of each 
 nervous fibre ; and that the passage of the injection from one fibre to a great number of 
 others depends on the canals formed by the proper sheaths anastomosing with each other. 
 
 I shall farther remark, that in this injection the mercury evidently penetrates into a 
 regular canal, and not into one produced by its own weight, for a column of a few lines 
 IS sufficient for the purpose. 
 
 Again, the mercury runs more easily from the peripheral towards the central extrem- 
 ity of a nerve than in the opposite direction, and when the injection is successful, the 
 spinal ganglia are filled with the mercury, which is then either extravasated into the cav- 
 ity of the dura mater, or escapes by the veins. If it be asked why the mercury does not 
 pass into the anterior and posterior roots of the nerves 1 I should answer, that it is not 
 certain that the fibres of these roots have any proper sheaths ; or, if so, they are very 
 readily lacerated. As to the passage of the mercury from the nervous ganglia into the 
 veins, it is probable that the proper sheaths terminate in the ganglia, so that the mercu- 
 ry is extravasated into the tissue of which the ganglia consist. 
 
 Injections afford a good means of tracing the nervous filaments into the substance ot 
 organs. An injection thrown into the lingual branch of the fifth nerve penetrates as far 
 as the papillae of the tongue. 
 
 Structure of the Ganglia. 
 
 Meckel, in his excellent monograph upon the fifth pair, advanced the opinion that the 
 nerves divided in the ganglia into a multitude of fibres which are intended for a great 
 number of parts. 
 
 Zinn (Acad. Berlin, 1755) said that the nerves not only divided within the ganglia into 
 a great number of fibres, and were directed by them from the centre to the circumference, 
 but that they were also mingled and combined in the ganglia in such a manner that a 
 great number of fine fibres united into a smaller number of fibres of greater diameter. 
 
 But this doctrine, however specious it may be, not resting upon any anatomical fact, 
 was rejected by Haller. Scarpa undertook a series of researches in order to render our 
 knowledge more complete regarding this subject. Instead of boiling the ganglia or ma- 
 cerating them in vinegar, urine, and other hquids, Scarpa was contented with macera- 
 ting them in pure water frequently renewed — a method practised by Ruysch in his del- 
 icate investigations ; by means of this simple proceeding, he was able to demonstrate 
 that the ganglia are formed by a number of nervous filaments sun'ounded by cellular tis- 
 sue, and by a gray matter which is destroyed by maceration.* 
 
 * [The gray mattf r of the ganglia consists, like that of the brain and spinal cord, of reddish nucleated glob- 
 
DESCRIPtieSf df "THE NERVES. 
 
 He carried his researches not only into the anatomy of the spinal, but also into that 
 of the visceral ganglia, and he discovered a wonderful uniformity in the structure of the 
 one and the other. He compared their structure to that of the plexuses ; both of them 
 receive nerves from all sides, which nerves are then intermixed without becoming uni- 
 ted ; and both generally give off a greater number of nerves than have assisted in their 
 formation. 
 
 The injection of the nervous ganglia from the nerves has enabled me to discover that 
 these ganglia have a precisely similar structure to that ofthe lymphatic glands ; they 
 are composed of cells communicating with each other, and among which the nervous 
 fibres are scattered. 
 
 In attempting to draw a comparison between the nervous plexuses, anastomoses, and 
 ganglia, it might be said that in the plexuses there was an exchange of nervous cords, 
 in the anastomoses, an exchange of nervous fibres, and in the ganglia, an exchange of 
 nervous filaments. 
 
 Preparation ofthe Merves. 
 
 For dissecting the nerves, a very emaciated subject, either young or old, should be 
 chosen. Old wasted subjects appear to me at least as favourable as young subjects. 
 
 The dissection of the spinal nerves is easy. Such is not the case with the cranial 
 nerves, the dissection of which is undoubtedly the most difficult part of practical anat- 
 omy. In order to faciUtate the study of these nerves, and to aid in the distinction ofthe 
 nervous filaments from small vessels and portions of fibrous tissue with which they are 
 often confounded, I am in the habit of submitting the head to the action of dilute nitric 
 acid. After having macerated it for some time in this acidulated fluid, I immerse the 
 Pfepafation in pure water, which I renew from time to time : the tissues generally, as 
 /well as the neurilemma, become perfectly transparent, and like jelly ; the nervous mat- 
 /^ ter alone remains whiter and more consistent, and then all error becomes impossible. 
 Besides, the bones, when thus deprived of their phosphate of lime, may be cut like the 
 soft "parts. In this way I have succeeded in separating the entire cerebro-spinal nervous 
 system from the other organs, retaining the great sympathetic in connexion with the 
 rest of the nervous system. 
 
 DESCRIPTION OF THE NERVES. 
 
 General Remarks. — Division into Spinal, Cranial, and Sympathetic Nerves. 
 
 The nerves are divided into two very distinct sets : the cerebro-spinal nerves, whicn 
 have their origin or central extremity in the spinal cord or its cranial prolongations : 
 these are the nerves of relation or of animal life ; and the ganglionic nerves, or nerves of 
 the great sympathetic, which end in or emanate from certain ganglia : these belong to the 
 system of nutrition or of organic life. 
 
 The cerebro-spinal nerves are divided into the spinal or rachidian, and the cranial 
 nerves : the first consist of all those which emerge from the inter-vertebral foramina ;* 
 the second, so improperly termed the cerebral or encephalic nerves, emerge from the 
 foramina at the base of the cranium. 
 
 As the line of demarcation, which seems, at first sight, to separate the cranium from 
 the spinal column, disappears on an analytical study ofthe scull and on a comparison of 
 it with the vertebrae, so it will be found that the cranial nerves, notwithstanding their 
 apparent irregularity, approach, in many respects, to the simplicity and regularity of the 
 spinal nerves. From such a comparison of the cranial with the spinal nerves we shall 
 derive the general principle, that the situation at which the nerves emerge from their 
 osseous cavities is altogether of secondary importance, while the fundamental points in 
 their anatomy are the exact situation of their central extremity, and their mode of distri- 
 bution to their peripheral extremity ; we shall also find that the only ratiofial basis of a 
 good classification of the nerves must be derived from the consideration of their origin. 
 
 In my opinion, the only difference between the cranial and spinal nerves is, that the 
 former arise from the medulla oblongata and its cranial prolongations, while the latter 
 arise from the spinal cord below the medulla oblongata. Just as in the osteological di- 
 vision of this work I have described the vertebra before the cranium, so I shall now de- 
 scribe the spinal before the cranial nerves ; this slight modification in the order gener- 
 edly adopted will enable the student to pass from the simple to the complex, and to defer 
 the study of the very complicated nerves of the cranium until he has been accustomed 
 to the dissection and examination of other nerves. 
 
 The following is, therefore, the order I shall adopt in describing the nerves : the spi- 
 nal nerves, the cranial nerves, the ganglionic or visceral nerves. 
 
 ules, and of grray, jointed fibres, which surround and adhere to the globules, and which are most abundant in 
 the ganglia of the sympathetic. The white fibres in the ganglia are like those of the nerves with which they 
 are continuous ; they interlace among the globules, but do not anastomose ; it has been supposed that some 
 wh'te fibres may originate or terminate in the ganglia, but this is not established.] 
 * It will be recollected that we have included the sacral foramina among the invertebral. 
 
 5E 
 
7TO NEUROLOGY. 
 
 THE SPINAL NERVES. . .. - . . • 
 
 Enumeration and Classification. — The Central Extremities or Origins of the Spinal Nerves 
 — Apparent Origins — Deep or Real Origins. — The Posterior Branches of the Spinal 
 Nerves — Common Characters — the Posterior Branches of the Cervical Nerves, their Com- 
 mxtn and Proper Characters — the Posterior Branches of the Dorsal, Lumbar, and Sacral 
 Nerves. — The Anterior Branches of the Spinal Nerves — their General Arrangement. 
 
 The number of the spinal nerves, that is to say, of the nerves which peiss through the 
 inter-vertebral foramina, including the sacral foramina, is entirely dependant on the 
 nimiber of the vertebrae.* 
 
 There are eight pairs (1 to 8,fg. 268) of cervical nerves, including the sub-occipital ; 
 twelve of dorsal (9 to 20) ; five of lumbar (21 to 25) ; and six of sacral nerves (26 to 31) ; 
 in all, thirty-one pairs. 
 
 They all have certain characters in common ; and there are also characters proper to 
 certain regions, and, lastly, characters proper to each nerve. 
 
 We shall proceed to examine, under these three points of view, the central extrem- 
 ity, the course, and the termination of the spinal nerves. 
 
 The Central Extremities or Origins of the Spinal Nerves. 
 
 The Apparent Origins of the Spinal J^erves. 
 
 Dissection. — The same as that of the spinal cord. 
 
 Common Characters. 
 
 There are very close analogies, and only slight differences, between the different spi- 
 nal nerves, in regard to their origin and course within the spinal canal. This circum- 
 stance, added to the fact that the same dissection is required to expose the origins of 
 the whole series of spinal nerves, has appeared to me a sufBcient reason for including 
 them all in one common description. Such a plan, the object of which is to study anal- 
 ogous parts by comparison, is infinitely preferable to one in which the origin of each 
 pair of nerves is separately described. 
 
 The spinal nerves arise from the spinal cord by a double row of filaments, or by two 
 series of roots. These roots are distinguished into the anterior (a a, Jig. 267), which 
 come off from each side of the anterior surface of the cord, and the posterior (h b), which 
 come off also from each side of the posterior surface. The latter are also named the 
 ganglionic roots, because they are more particularly connected with the spinal nervous 
 ganglia {b b). 
 
 The ligamentum denticulatum (c c) is situated between these two series of roots. 
 
 Immediately after leaving the cord, both the anterior and posterior roots are collected 
 Into a number of groups corresponding to the number of the spinal nerves ; the nervous 
 cords of which each group consists converge towards each other, the superior cords de- 
 scending to meet the inferior, which is soon accomplished from the latter being less ob- 
 lique in their direction. It follows, therefore, that the filaments of each root, situated 
 one above the other, widely separated from each other on the inside, and approximated 
 on the outside, represent a triangle, the general inclination of which to the axis of the 
 cord varies in each particular region. Not unfrequently the filaments, especially those 
 of the anterior roots, form two secondary groups. 
 
 As they are about to enter the separate fibrous canal formed for them by the dura 
 mater, the fibres of each of the anterior roots, and also those of each posterior root, are 
 collected into a flattened cord. There is one fibrous canal for each cord of the anterior 
 roots, and another for each cord of the posterior roots. The arachnoid membrane, 
 which forms a common funnel-shaped sheath for both roots of each spinal nerve, is re- 
 flected from them at the points where they enter the fibrous canals of the dura mater, 
 to which the nervous cords are rather firmly attached. 
 
 Although the corresponding groups of anterior and posterior roots approach each other 
 to pass through the fibrous canals of the dura mater, there is never the slightest com- 
 munication between them. It is curious to see the long and numerous cords or fila- 
 ments which constitute the cauda aquina running parallel to each other without any an- 
 astomoses, while, as soon as they emerge from the spinal canal, their communications 
 are almost continual. 
 
 Communications between the filaments of the same series, whether anterior or pos- 
 terior, are not rare ; they take place in several different ways : thus, sometimes two 
 filaments belonging to the same nerve unite, sometimes the filaments of two different 
 nerves are combined, and at others, again, a filament intermediate to two nerves bifur- 
 cates and is divided between them. 
 
 Moreover, the oblique direction of the roots of the spinal nerves, and the variable 
 length of their course within the spinal canal, are the necessary consequences of the 
 
 * This relation between the number of the spinal nerves and the number of the vertebrs prevails through- 
 .out the whole series of vertebrate animals ; and, accordingly, there are about sixty spinal nerves in certain 
 Hsuunmalia, and several hundred in some serpents. 
 
APPARENT ORIGINS OP THE NERVES. wl^ 
 
 relative shortness of the cord, which, as it terminates opposite the first lumhaTvertobra. 
 cannot give origin to adl the nerves opposite the inter-vertebral foramina, through which 
 they have to pass.* 
 
 The differences between the anterior and posterior roots may be collected under the 
 following heads : 
 
 The anterior roots arise nearer to the median line than the posterior ; they approach 
 nearer and nearer to that line, towards the lower part of the cord, so tba in this situa- 
 tion they arise from each side of the median fissure. 
 
 While all the posterior roots are given off from a longitudinal furrow of gray sub- 
 stance, from which they never deviate, the anterior roots arise somewhat irregularly, 
 and, as it were, confusedly, from a small white column about half a line in breadth. 
 
 In regard to size, the posterior roots, taken separately, are much larger than their 
 corresponding anterior roots ; besides this, the filaments of the posterior roots are more 
 numerous, so that the posterior roots, taken together, are larger than the anterior, as 
 Soemmering, Chaussier, and Gall have very well established. It is difficult to conceive 
 how some authors should have entertained the opinion that the proportion between them 
 is just the reverse, at least in some regions ; this error has, doubtless, arisen from the 
 varieties which exist in different regions of the medulla, in the relative sizes of the an- 
 terior and posterior roots, but which are never such as to give the advantage in point 
 of size to the anterior roots : opposite the inter-vertebral foramina, the series of cords 
 formed by the anterior roots have a different arrangement from those formed by the pos- 
 terior roots. 
 
 The cord formed by each of the posterior roots immediately swells out and forms an 
 olive-shaped ganglion, which is called a vertebral or spinal ganglion {b b, Jig. 267). Haase, 
 and then Scarpa, clearly proved that, in gener£il, the posterior roots alone passed into the 
 spinal ganglia, and hence they are often denominated the ganglionic roots : the spinal 
 ganglia are situated in the inter-vertebral foramina, those of the sacral region are en- 
 closed in the sacral canal. 
 
 Though it is generally to the nervous cord which emerges from this ganglion that the 
 cord of the anterior root is applied and united, yet I would hasten to observe, that the 
 anterior root is not so completely unconnected with the ganglion as is commonly stated ; 
 thus, not unfrequently the fibres of the anterior root are united either to the outer end or 
 to the middle of the ganglion ; and, moreover, in the lumbar and sacral regions there is 
 half a ganglion on each root. 
 
 There are thirty pairs of spinal ganglia, and occasionally thirty-one, when the first 
 pair of cervical nerves or the sub-occipital nerves are provided with them : the size of 
 the ganglia bears no proportion to the diameter of the inter-vertebral foramina, but de- 
 pends on the number and size of the filaments of origin which pass into them, and of the 
 nerves which are given off from them. 
 
 The cord which emerges from the ganglion is cylindrical, has a plexiform structure, 
 and a furrowed aspect ; it is impossible to ascertain what part of it belongs to the ante- 
 rior and what to the posterior root ; it gives off three sets of branches : the posterior 
 spinal branches, which supply the muscles and integuments of the posterior spinal region ; 
 the anterior spinal branches (see Jig. 268), the true continuation of the nerve, which are 
 distributed to the lateral and anterior parts of the trunk, and to the upper and lower ex- 
 tremities ; and the ganglionic spinal branches, which pass to the ganglia of the great 
 sympathetic (/ i u). 
 
 The ganglionic branches will be described with the ganglia of the great sympathetic. 
 As the posterior branches have a close analogy in their mode of distribution, and may 
 be exposed in the same dissection, they will be described under one head. 
 
 The anterior branches being destined for dissimilar parts, their individual distribution 
 is exceedingly varied and complicated, so that a particular description is requisite, if not 
 of the anterior branches of each nerve, at least of those of the several sets of nerves. 
 
 Such are the characters common to all the spinal nerves at their central extremities, 
 during their course within the vertebral canal, and at their exit from the inter-vertebral 
 foramina. Let us next examine the characters proper to the nerves of each region. 
 
 Proper Characters of the Apparent Origins of the Nerves. 
 
 Proper Characters of the Cervical Nerves. — The roots of these nerves (1 to 8, Jig. 268) 
 are much less oblique than those of the other spinsil nerves. The first cervical nerve 
 slopes a little upward and outward, like the cranial veins, which it resembles in this re- 
 spect. The second nerve is transverse ; the succeeding nerves slope downward and 
 outward, the lowest being the most oblique ; but their obliquity never exceeds the depth 
 of a single vertebra. 
 
 The proportion between the size of the posterior and anterior roots is as 3 to 1 ; and 
 
 * Gall believed that he had solved this question, by saying that the length and obliquity of the course of 
 he spinal nerves is a necessary result of the erect position of man. It is certain that the nerves are less ob- 
 ique and have a shorter course v^ithin the vertebral canal in the lovirer animals; but this difference is ex- 
 plained by the greater length of the spinal cord in them, and has nothing to do with the :itf;todf>. 
 
772 NEUROLOGY. 
 
 this difference, which is much greater than is observed in any other region, obtains not 
 only in reference to the filaments taken altogether, but also to each particular filament. 
 
 The cervical nerves increase rapidly in size from the first to the fifth, and then main- 
 tain the same size to the eighth. 
 
 The first cervical nerve, so well described by Asch, has some peculiarities : its pos- 
 terior filaments of origin are much less numerous than the anterior, the spinal accessory 
 of Willis appearing to supply this deficiency ; it is also frequently without a ganglion.* 
 
 Proper Characters of the Dorsal Nerves. — Excepting the first, which has all the charac- 
 ters of the cervical nerves, the roots of the dorsal pairs of nerves (9 to 20) present the 
 following peculiarities : 
 
 A small number of filaments or roots ; so that, with the exception of the sacral, the 
 dorsal are the smallest of all the spinal nerves. 
 
 Uniformity in the number of the filaments, i e., in the size of their roots. The dorsal 
 nerves are almost of equal size, the twelfth nerve alone being somewhat longer than 
 the rest. 
 
 A considerable interval between their roots, and a want of regularity in this interval. 
 Frequently a portion of the spinal cord, from eight to ten lines in length, gives origin to 
 only a small pair of nerves. 
 
 A more marked slenderness of the filaments of origin than in any other region. 
 
 The slight disproportion between their anterior and posterior roots when compared 
 filament for filament. 
 
 The direction of their roots, which remain in contact with the cord for some distance, 
 and then leave it ; this circumstance is calculated to give rise to errors concerning the 
 precise situation of their origin. 
 
 The length of their course within the spinal canal ; this length is equal to the height 
 of at least two vertebrae. 
 
 Proper Characters of the Lumbar and Sacral Nerves. — The roots of these nerves form 
 the Cauda equina ; their characters are, the great number of their filaments of origin, 
 which exceeds those of the dorsal, and even those of the cervical nerves. 
 
 The extreme closeness of these filaments, which form an uninterrupted series. 
 
 The proportion between the filaments of the anterior and those of the posterior roots, 
 which is as 2 to 1. 
 
 The uniformity in point of size between the two sets of filaments, the anterior fila- 
 ments, taken individually, being as large as the posterior. 
 
 The continuance of the origin of the posterior roots to take place at the groove, while 
 the anterior approach nearer and nearer to the median line towards the lower part of 
 the cord, and almost touch those of the opposite side. 
 
 The concurrence of both the anterior and posterior roots in the formation of the spi- 
 nal ganglia. 
 
 The almost vertical direction of the roots, a character common to both the lumbar 
 and sacral pairs of nerves. 
 
 The singular length of their course before they emerge from the spinal canal.t 
 
 The Real Origins of the Spinal Jferves. 
 
 The apparent central extremity or origin of the spinal nerves is very different from their 
 real central extremity or real origin. On examining the spinal cord of an adult, for the 
 purpose of determining this important point, one is inclined to admit that the point of 
 contact between any nerve and the cord is the real origin of the nerve, so readily can 
 the latter be separated from the cord without leaving any trace of the separation. 
 
 It has even been stated by some that the nerves arise from the neurilemma of the 
 spinal cord. 
 
 Chaussier believed that the two series of roots arose from two lateral furrows, one 
 anterior and the other posterior ; but Gall has with reason regarded these furrows as 
 formed by pulhng off the roots. 
 
 Others agree with the older anatomists in regarding the spinal cord as a large nerve 
 formed by the junction of all the nervous filaments which are given off from it. But 
 this idea is refuted by the fact that the cord does not progressively diminish in size from 
 above downward, as it must have done if fonned by the junction of the roots of the spi- 
 nal nerves. 
 
 The ingenious and correct observation made by Vicq d'Azyr, that the gray matter is 
 always found in large quantity at those parts from which a great number of nerves ori- 
 ginate, and that it bears a proportion to the number of these nerves, and the confirma- 
 tory observations of Gall and Spurzheim, seem to prove that the nerves originate from 
 the gray matter. This presumption is also strengthened by the consideration, that the 
 
 * According to the principles of classification which I have already stated, I should range the spinal acces- 
 sory nerve among the cervical nerves, because it originates from the cervical portion of the spin;il cord : iu 
 classing it among the cranial nerves, 1 yield to general usage. 
 
 t [Lastly, the situation of the ganglia of the sacral nerves within the sacral canal, and of the lowest of 
 them within the cavity of the dura mater.l 
 
POSTERIOR BRANCHES OP THE CERVICAL NERVES 773 
 
 central gray substance of the cord is more abundant opposite the posterior roots, which 
 are the larger, than opposite the anterior roots, which are the smaller. On examining 
 the spinal cord of an adult by means of a stream of water, it is seen that, after tearing 
 away the filaments of the nerves, a small conical depression remains where each fila- 
 ment had been attached, and that the real origin of the filaments is not in this depression, 
 but is much more deeply seated. This is all that can be discovered from an examina- 
 tion of the spinal cord of the adult ; but in the foetus, at the seventh or eighth month, a 
 considerable part of the cord is semi-transparent, so that the already white filaments by 
 which the nerves arise can be traced into its interior. On making a vertical section 
 transversely through the spinal cord of the foetus, just level with the commissure, and 
 then directing a strong light on the surface of the section, it will be seen that the great 
 number of very delicate filaments of which the anterior and posterior roots of the spinal 
 nerves are composed traverse the central gray matter, are arranged like the teeth of a 
 comb, and may be traced into the posterior median columns ; these small filaments, are, 
 moreover, all parallel. The white coimnissure might ahnost be regarded as the com- 
 missure of these nerves. 
 
 This view is very different from that of Bellingeri, who, entertaining certain physio- 
 logical ideas, supposes that the anterior as well as the posterior roots of the spinal 
 nerves consist of three sets of filaments, some of which come from the surface of the 
 cord, others from the interior of the white matter, while the third set traverse the white 
 matter, so as to reach the extremities of the cornua of the gray substance. 
 
 Lastly, some anatomists agree with Santorini in believing that the nerves decussate 
 at their origin ; but they have not attempted to demonstrate this. 
 
 The Posterior Branches of the Spinal Nerves. 
 Dissection. — Divide the integuments from the external occipital protuberance down to 
 the coccyx. Dissect off the skin over the spinous processes with great care, especially 
 opposite the trapezius. Be particularly cautious opposite the cellular interval between 
 the sjicro-lumbaJis and the longissimus dorsi. 
 
 Common Character's. 
 
 The posterior branches of the spinal nerves, which are generally smaller than tne anit- 
 rior branches, emanate from the plexiform cords which form the continuation of the cor- 
 responding spinal ganglia, are directed backward, and immediately pass through tlic fora- 
 mina, which I may regard as posterior inter-vertebral foramina.* These branches sub- 
 divide into several twigs, which enter the great cellular intervals between the long mus- 
 cles of the back, and are distributed to the muscles of the integuments. The greatest 
 uniformity prevails among such of these nerves as are distributed to the same kinds of 
 organs, and their differences depend on peculiarities in the parts to which they belong. 
 
 We shall now study in succession the posterior branches of the cervical, dorsal, and 
 Iimibar spinal nerves. 
 
 The Posterior Branches of the Cervical Serves. 
 
 Common Characters. 
 All the posterior branches of the cervical nerves (« to o', fig. 300) pass transversely 
 inward between the complexus and the semi-spinalis colli, haviiig first given off some 
 very small twigs : having reached the sides of the posterior cervical ligament, thoy per- 
 forate the aponeurotic attachments of the trapezius from before backward, lie close be- 
 neath the skin, and are directed transversely outward. The course of these branches, 
 therefore, is at first inward, and then outward. The posterior branch of the first cervi- 
 cal nerve is the only one which presents any exception to these general characters. 
 
 Proper Characters. 
 The Posterior Branch of the First Cervical Nerve. 
 
 The posterior branch of the first cervical or sub-occipital nerve, larger than the anterior 
 branch, escapes between the occipital bone and the posterior arch of the atlas, on the 
 inner side of the vertebral artery, with which it is in contact, below the rectus capitis 
 posticus major, and in the area of the equilateral triang'e formed by that with tlie two 
 oblique muscles ; in this situation (i, fig. 300) it is concealed by a large quantity of fatty 
 tissue, which renders it rather difficult of dissection ; and it immediately divides into 
 several branches, which may be arranged into the internal, which go to the great and 
 small recti muscles ; extertud, which supply the great and small oblique muscles ; and 
 inferior or anastomotic, which, by uniting with the second cervical nerve, assist in the 
 formation of the posterior cervical plexxts. 
 
 The branch to the rectus minor passes at first between the rectus major and the com- 
 plexus, and then reaches the rectus minor. 
 
 * Vide Osteology (vertebral column in general). Tiies-- n.ra .j. ;. are situated between the transverse 
 processes, and in the dorsal region are cumpliti^d on ihu .uiTs.ue ii. . MsnKrior costo-transverse ligament. 
 
774 NEUROLOGY. 
 
 The principal branch for the inferior oblique, before ramifying in that muscle, forms 
 an arch or loop, which has been well described by Bichat. 
 
 It follows, therefore, that both of the recti and both of the oblique muscles are supplied 
 by the first cervical nerve, which gives no filament to the complexus,* and none to the skin. 
 
 The Posterior Branch of the Second Cervical Nerve. 
 
 This is the largest of all the posterior branches of the cervical nerves, and is three or 
 four times larger than the anterior branch of the same nerve ; it emerges («■, fig. 300) 
 from the spine, between the posterior arch of the atlas and the corresponding lamina of 
 the axis, in the same line as the posterior branch of the first nerve, immediately below 
 the lower border of the obliquus major, and is reflected upward between the hairy scalp 
 on the one hand, and the occipitalis muscle and epicranial aponeurosis on the other ; it 
 passes horizontally inward between the obliquus major and the complexus, perforates 
 this last muscle in the outer side of its digastric portion (the biventer cervicis), then 
 changes its direction, and turns outward between the complexus and the trapezius, 
 through which latter it passes to become sub-cutaneous and accompany the occipital ar- 
 tery ; it is here called the great occipital nerve (occipitalis major, a, fig. 285). Hither- 
 to cylindrical, this nerve, on becoming sub-cutaneous, is flattened, and increased in 
 width, and then, passing upward, spreads out into a considerable number of diverging 
 branches, internal, middle, and external, which cover the occipital region with their 
 ramifications, and may be traced even to the parietal region : the internal branches are 
 the shortest, and are successively lost in the skin of the occipital region. 
 
 It supplies several branches, as follows : Some anastomotic branches to the first and third 
 cervical nerves. 
 
 Opposite the lower border of the obliquus major, it gives off a considerable muscular 
 branch (w, fig. 300), which is distributed to that muscle, to the complexus, and especial- 
 ly to the splenius (w, fig. 298) ; the branches to the splenius are of great size, and spread 
 upon its deep surface into diverging twigs, which anastomose both with each other and 
 with branches derived from the third cervical nerve. 
 
 During its passage between the obliquus major and the complexus, and between the 
 last-named muscle and the trapezius, the posterior branch of the second cervical nerve 
 supplies these different muscles with a rather large number of nervous twigs. 
 
 Its sub-cutaneous portion is distributed exclusively to the hairy scalp. The occipi- 
 talis muscle, upon which it ramifies, does not receive any branch from it : as we shall 
 elsewhere show, this muscle is supplied by the auricular branch of the facial nerve. 
 The subdivisions of the sub-cutaneous portion of the second cervical nerve may be tra- 
 ced into the hair follicles, and several of its external branches anastomose with the mas- 
 toid branch of the anterior cervical plexus. 
 
 The Posterior Branch of the Third Cervical Nerve. 
 
 The posterior branch of the third cervical nerve, smaller than that of the second, but 
 much larger than that of the fourth nerve, and partially intended for the occipital region, 
 emerges between the transverse process of the atlas and that of the third cervical ver- 
 tebra, and, consequently, farther outward than the posterior branches of the first and sec- 
 ond nerves ; it is immediately curved, and passes transversely inward (t, fig. 300) be- 
 tween the complexus and the semi-spinalis colli. Having reached the inner border of 
 the complexus, it divides into two cutaneous branches : an ascending or occipital, which 
 perforates the innermost fibres of the complexus, passes vertically upward upon one side 
 of the median line, applied to the under surface of the skin, and ramifies upon the occip- 
 ital region, near the median line, and to the inner side of the branch from the second 
 cervical nerve ; and a horizontal or cervical branch, which perforates the aponeurosis of 
 the trapezius between the complexus and the posterior cervical ligament, and passes 
 horizontally outward beneath the skin, to which it adheres, and in the substance of 
 which it terminates 
 
 As the posterior branch of the third cervical nerve emerges from the posterior inter- 
 vertebral foramen, it gives off an ascending branch, which forms an anastomotic arch 
 with the descending branch of the second nerve : the succession of arches formed by the 
 anastomoses of the first, second, and third nerves, and the very numerous branches 
 which arise from their convexities, constitute a plexus, which may be called the posterior 
 cervical plexus : it is situated beneath the complexus, near its external attachments, and 
 it supplies both that muscle and the splenius. The direct anastomoses between the pos- 
 terior branches of the three superior cervical nerves appear to me to be sometimes want- 
 ing ; but then the branches given off from them still exist, and form a plexus between 
 the splenius and the complexus. 
 The Posterior Branches of the Fourth, Fifth, Sixth, Seventh, and Eighth Cervical Nerves. 
 
 The posterior branches of the fourth, fifth, sixth, seventh, and eighth cervical nerves are much 
 smaller than the preceding, and diminish in size successively from the fourth to the 
 
 * [Asch saw and has described a twig {m,fig. 300) proceeding from the posterior branch of the first cenri- 
 «al nerve to the complexus muscle ; Swan and Arnold Iso observed it.] 
 
POSTERIOR BRANCHES OF THE DORSAL NERVES. TT6 
 
 seventh. Immediately after their exit from the posterior inter- vertebral foramina, they 
 are reflected inward and downward in the following manner : the fourth and fifth (o') in- 
 cline downward upon the semi-spinalis colli, between it and the complexus ; the sixth, 
 seventh, and eighth descend ahnost vertically beneath the lowest fasciculi of the semi- 
 spinalis colli, supply that muscle and the raultifidus spinae, and having reached the side 
 of the median line, perforate the aponeuroses of the splenius and trapezius, become ap- 
 plied to the skin, and ramify in it. 
 
 The Posterior Branches of the Dorsal, Lumbar, and Sacral JVerve. 
 
 The Posterior Branches of the Dorsal Nerves. — These are intended for the dorsal region of 
 the trunk, and resemble each other closely in their distribution, presenting only a few dif- 
 ferences connected with the arrangement of the particular muscular layers of each region. 
 
 The posterior branch of the first dorsal nerve has the same muscular and cutaneous re- 
 lations as the corresponding branches of the lower cervical nerves ; it is of the same 
 size, and is distributed in precisely the same manner. 
 
 The posterior branches of the second, third, fourth, fifth, sixth, seventh, and ei^A^A dorsal 
 nerves are destined for the thorax, properly so called, and present the greatest uniformity 
 in their size and distribution. 
 
 They all emerge from the posterior inter-vertebral foramina, immediately on the outer 
 side of the semi-spinalis dorsi and multifidus spinae, and divide into two branches. The 
 external or muscular branch is directed towards the cellular interval between the sacro- 
 lumbalis and longissiraus dorsi, and subdivides into a great number of twigs, which are 
 distributed to these two muscles [and to the levatores costarum]. The internal or mus- 
 culo-cutaneous branch has a very remarkable course. It is reflected inward over the semi- 
 spinalis dorsi, embracing the outer border of that muscle, and supplying it with nervous 
 twigs ; having reached the side of the spinous process, it is reflected backward along 
 that process, perforates the spinal attachments of the latissimus dorsi, and thus gains 
 the under surface of the trapezius ; in this situation it is reflected outward between the 
 latissimus dorsi and the trapezius, perforates the latter muscle very obliquely, and be- 
 comes sub-cutaneous ; it then passes horizontally outward in the fonn of a small nervous 
 riband, the distinct fibres of which do not disunite and spread out in the substance of 
 the skin until they have arrived at the scapular region. The cutaneous branch, which 
 belongs to the second dorsal nerve, always corresponds to the triangular surface on the 
 spine of the scapula, over which the aponeurosis of the trapezius glides. 
 
 In one subject which I examined, the musculo-cutaneous divisions of the posterior 
 branches of the third, fourth, and fifth dorsal nerves presented two ganglia at the point 
 where they bifurcated into their muscular and cutaneous branches ; in another, the 
 ganglia were situated upon the cutaneous branches belonging to the first and third dor- 
 sal nerves. All these cutaneous branches are horizontal, parallel, and separated from 
 each other by an interval corresponding to the height of one vertebra. Such of the pos- 
 terior branches of the dorsal nerves as are in relation with the trapezius always present 
 the preceding arrangement. But the branches lower down than that muscle are dis- 
 tributed in the following manner : 
 
 The posterior branches of the ninth, tenth, eleventh, and twelfth dorsal nerves are distribu- 
 ted in precisely the same way as the posterior branches of the lumbar nerves, and, like 
 them, are intended for the abdominal parietes. 
 
 There is no longer any internal or musculo-cutaneous branch, the external branch 
 representing both the muscular and the cutaneous branch.* 
 
 Immediately after emerging from the inter-vertebral foramina, these posterior branches 
 pass very obliquely downward and outward, gain the cellular interval between the sacro- 
 iumbalis and the longissimus dorsi, or, rather, pass very obliquely through the common 
 mass formed by the union of the sacro-lumbalis and longissimus dorsi, and almost al- 
 ways communicate with each other during their long course through the fleshy fibres ; 
 having arrived opposite the outer border of the latissimus dorsi, or of the common mass, 
 these branches, diminished fully one third in consequence of having supplied the poste- 
 rior spinal muscles, perforate very obliquely the aponeurotic layer formed by the union 
 of the aponeuroses of the latissimus dorsi and serratus posticus inferior, with those from 
 the internal, oblique, and transverse muscles of the abdomen, and become sub-cutaneous ; 
 they then divide into some very small internal cutaneous filaments, whicli are directed 
 inward upon the side of the spinous processes, and some large external cutaneous fila- 
 ments, which descend to terminate in the skin of the gluteal region. I would especially 
 notice several large nerves, which, either joined together, or only in contact, descend 
 vertically, cross perpendicularly over the crest of the ilium in front of the outer border 
 of the common mass of the lumbar muscles, and become applied to the integuments of the 
 gluteal region, upon which they may be traced as far as the great trochanter. 
 
 * iThe internal branches of the four lower nerve.s are not absent, but are much reduced in size, do not 
 reach the surface, and are distributed principally to the multifidus spinae: the external branches give the 
 cutaneous twigs. (Demonstrations of Anatomij, by G. V. Ellis, of whose labours in reference to the anatomy 
 of the nerves, free use has been made in this and many of the succeeding notes.)] 
 
776 NEUROLOGT. 
 
 The Posterior Branches of the Lumbar Nerves. — These resemble in their distribution the 
 corresponding branches of the four lower dorsal nerves ; they gradually diminish in size 
 from above downward ; the fifth is extremely small, and is entirely expended in the 
 common mass of the lumbar muscles. 
 
 The Posterior Branches of the Sacral Nerves. — These branches emerge from the poste- 
 rior sacral inter-vertebral foramina. It is difficult to dissect them, because they are 
 extremely small, and penetrate immediately into the muscular mass which occupies the 
 sacral groove ; they moreover decrease in size from above downward, and are uniformly 
 arranged in the following manner : immediately after their exit from the posterior inter- 
 vertebral foramina, they form anastomotic arches with each other, from which muscular 
 and cutaneous filaments are given off. The former are distributed to the common mass 
 and the glutaeus maxiraus, and the latter are intended for the skin of the sacral region.* 
 
 The Anterior Branches of the Spinal Nerves. 
 
 The anterior branches of the spinal nerves, which are generally larger than the posterior, 
 are the true continuations of these nerves, and supply the lateral and anterior parts of 
 the trunk, and also the upper and lower extremities. 
 
 Such of these branches as are intended for the trunk of the body have an extremely 
 uniform and very simple mode of distribution ; to this class belong the intercostal 
 nerves : those, on the other hand, which are intended for the upper and lower extremi- 
 ties, present, in their distribution, a degree of complexity which depends on that of the 
 parts which they supply. To this class belong the anterior cervical, anterior lumbar, and 
 anterior sacral branches. 
 
 The three last-named sets of branches, almost immediately after their exit from the 
 spinal canal, communicate with each other, so as to form interlacements or plexuses, 
 from which are given off the nerves, that ultimately ramify in all parts of the body. 
 
 There are four great plexuses : two for the region of the neck and the upper extrem- 
 ity, viz., the cervical plexus (x,fig. 268) and the brachial plexus (h), which might be re- 
 garded as a single plexus, the cervico-brachial ; and two for the lumbar region and the low- 
 er extremity, viz., the lumbar (/) and the sacral or crural plexus (s), which also might be 
 regarded as one, the lumbosacral plexus. 
 
 After these preliminary observations, I shall now describe, in succession, the anterior 
 branches of the cervical, dorsal, lumbar, and sacral nerves. 
 
 THE ANTERIOR BRANCHES OF THE CERVICAL NERVES. 
 
 Dissection. — Anterior Branch of the First, Second, Third, and Fourth Cervical Nerves. — 
 The Cervical Plexus — Its Anterior Branch, the Superficial Cervical — Its Ascending 
 Branches, the Great Auricular and the External or Lesser Occipital — Its Superficial De- 
 scending Branches, the Supra-clavicular — Its Deep Descending Branches, the Nerve to the 
 Descendins Noni and the Phrenic — Its Deep Posterior Branches. — The Anterior Branches 
 of the Fifth, Sixth, Seventh, and Eighth Cervical, and First Dorsal Nerves. — The Brach- 
 ial Plexus. — Its Collateral Branches above the Clavicle — Its Muscular Branches, Poste- 
 rior Thoracic, Supra-scapular, opposite to the Clavicle, the Thoracic, below the Clavicle, the 
 Circumflex — Its Terminal Branches, the Internal Cutaneous and its Accessory, the Mus- 
 culo-cutaneous, the Median, the Ulnar, the Musculo-spiral or Radial. — Summary of the 
 Distribution of the Branches of the Brachial Plexus. 
 
 Dissection. — It is convenient to dissect the sub-cutaneous branches which emerge 
 from the cervical plexus before examining the anterior branches of the cervical nerves : 
 one side of the neck may be reserved for the superficial, and the other for the deep 
 branches. 
 
 The Anterior Branches of the First, Second, Third, and Fourth Cervical Nerves. 
 
 The Anterior Branch of the First Cervical Nerve. — This branch {u. Jig. 300) emerges 
 from between the occipital bone and the posterior arch of the atlas in the groove for the 
 vertebral artery, and beneath that vessel ; opposite the foramen in the transverse pro- 
 cess of the atlas, it leaves the artery, passes in front of the base of that process, is re- 
 flected downward, and descends to form an anastomotic arch with the anterior branch 
 of the second nerve. As all the branches belonging to the first nerve come off from this 
 anastomotic arch, they will be described with the second nerve. 
 
 The Anterior Branch of the Second Cervical Nerve. — This is much smaller than the pos- 
 terior branch of the same nerve ; it passes horizontally forward between the transverse 
 processes of the atlas and axis, is reflected in front of the axis, and divides into an as- 
 cending and a descending branch. 
 
 * Among the cutaneous filaments which proceed from the arch formed by the jposterior branches of the first 
 and second sacral nerves, there i* one wliich passes below the posterior and inferior spinous process of the 
 ilium, is directed vertically downward between the glutieus m:i.\iraQs and the lesser sacro-sciatic ligament, 
 oerforates the gluUeus muxiiuus, and is then reflected outward in noutact with the skin. 
 
THE CERVICAL PLEXUS. 777 
 
 The ascending branch curves upward in front of the transverse process of the atlas, and 
 j^j^astomoses in an arch with the anterior branch of the first nerve. 
 ., The descending branch {z, fig. 298) subdivides into two others of almost equal size : the 
 .'one internal (see also fig. 300), which constitutes the internal descending cervical nerve 
 (before s, fig. 298) ; the other external (behind s), which anastomoses with the third nerve 
 ^.^above s), to form the superficial cervical nerve {k) and the great auricular nerve (q). 
 
 Several large filaments for the rectus capitis anticus major are given off from the angle 
 .of bifurcation of the ascending and descending branches. 
 
 ** The anastomotic arch formed by the anterior branches of the first and second cervi- 
 cal nerves gives off three or four very large grayish branches and several small white 
 filaments, which go to the superior cervical ganglion of the sympathetic ; above these it 
 gives a short gray filament, which almost immediately swells into a ganglion, from which 
 a long, slender, descending filament proceeds to join the internal descending nerve ; lastly, 
 it furnishes two ascending filaments, the lower one of which joins the pneumogastric 
 nerve, and the upper one the hypoglossal or ninth nerve. 
 
 The Anterior Branch of the Third Cervical Nerve. — This (above s, fig. 298) is twice as 
 * large as the preceding ; it at first passes forward to emerge from the inter-transverse 
 space, then downward and outward, and having gained the under surface of the stemo- 
 mastoid muscle, it expands into a great number of branches, which constitute the cervi- 
 cal plexus properly so called, and may be divided into a superior and an inferior portion. 
 
 The superior division passes outward and backward beneath the sterno-mastoid mus- 
 '■■«de, and bifurcates upon its posterior borders. One of the branches of the bifurcation as- 
 cends, and is called the mastoid nerve (y) ; the other, which is reflected over the posterior 
 border of the muscle, anastomoses by one or two filaments with the anterior branch of 
 the second cervical nerve, and subdivides into the superficial cervical nerve {k) and the 
 auricular nerve (q) : both of the branches of the bifurcation anastomose with the second 
 cervical nerve. This superior division, moreover, gives off a small nerve, which as- 
 cends between the auricular and mastoid nerves ; also a communicating branch to the 
 superior cervical ganglion ; and, lastly, a series of branches («), which anastomose with 
 the spinal accessory nerve of Willis (<), some immediately, and others while v/ithin the 
 substance of the sterno-mastoid muscle. This superior division of the third nerve some- 
 times joins the lowest branch of the second nerve. 
 
 The inferior or descending portion passes vertically downward in front of the scalenus 
 anticus, gives off a long slender filament to the internal desccndi7ig cervical nerve, and ter- 
 minates partly by anastomosing with the fourth cervical nerve (below s), and partly by 
 becoming continuous with the clavicular nerves (w). 
 
 A considerable branch which enters the levator anguli scapulas may be regarded as be- 
 longing to this inferior portion. This branch for the angularis sometimes arises at the 
 point of bifurcation of the anterior branch of the third nerve. 
 
 The Anterior Branch of the Fourth Cervical Nerve. — This branch (below s) is of the 
 same size as the preceding ; it gives off the phrenic nerve (J), which sometimes arises in 
 the inter-transverse space ; it then passes downward and outward in contact with the 
 scalenus anticus for about ten lines, and divides into two terminal branches, the one in- 
 ternal, the other external, which soon subdivide and cover the supra-clavicular triangle 
 with their diverging ramifications : these branches constitute the supra-clavicular and 
 acromial nerves (m). Just opposite its division the anterior branch of the fourth cervi- 
 cal ner\'e receives a branch from the third, which appears to be shared between its two 
 terminal divisions. 
 
 The fourth cervical generally sends off a small communicating branch to the fifth cer- 
 vical nerve. 
 
 The Cervical Plexus. 
 
 The term cervical plexus is applied to the series of anastomoses (z s) formed by the an 
 terior branches of the first, second, third, and fourth cervical nerves. 
 
 Some anatomists call it the deep cervical plexus, in contradistinction to the superficial 
 branches given off from it, which, according to this view, constitute the superficial cervi 
 cal plexus. 
 
 This plexus, which occupies the anterior and lateral aspect of the four superior cer- 
 vical vertebrae, is situated beneath the posterior border of the sterno-cleido-mastoid mus- 
 cle, to the outer side of the internal jugular vein, between the rectus capitis anticus ma- 
 jor and the cervical attachments of the splenius and levator anguli scapulae : it is con- 
 cealed by a considerable quantity of fat, and by a great number of lymphatic glands : it 
 is also covered by an aponeurotic lamina, which adheres to it intimately, and is prolong- 
 ed upon the nerves which emanate from it. 
 
 After the example of Bichat, this plexus may be regarded as a centre in which the 
 anterior branches of the four superior cervical nerves terminate, and from which a great 
 number of branches proceed. This plexus is by no means inextricable ; it is always 
 easy to determine the origin of the branches which come from it. 
 
 These branches consist of one anterior branch, the superficial cervical {k) ; of ascending 
 
 5 F 
 
778 
 
 NEUROLOGY. 
 
 branches, viz., the great mastoid (y), the small mastoid, and the great auricular (q) ; and 
 of descending branches, subdivided into the deep and the superficial ; the deep ones 
 consisting of the itUerjial descending branch (before s), the •phrenic nerve (/), and the branch- 
 es for the trapezius, levator anguli scapula, and rhomboideus ; the superficial descending 
 branches are the supra-clavicular and the acromial (m). 
 
 According to their distribution, they may also be divided into muscular and cutaneous 
 branches ; the muscular consist of the internal descending, the phrenic, the branches for 
 the trapezius, the levator anguli, and the rhomboideus ; all the others are cutaneous, 
 and are flattened like ribands. 
 
 The Ajiterior Branch. 
 
 The Superficial Cervical JVerve. 
 
 The superficial cervical nerve (superficialis colli, s, fig. 285), which is often double, 
 Pig. 285. in consequence of dividing earlier than usual, is des- 
 
 tined exclusively for the skin of the neck and lower 
 part of the face (sous-mentonniere, Chauss.), and is 
 formed by the anastomoses of the second and third 
 cervical nerves ; it emerges from the plexus opposite 
 the middle of the neck, beneath the posterior border 
 of the sterno-mastoid, around which it turns in the 
 form of a loop, and then passes horizontally forward 
 between that muscle and the platysma, runs at right 
 angles beneath the external jugular vein, and divides 
 into two branches — one ascending and larger, the oth- 
 er descending ; these two branches often form two 
 distinct nerves. 
 
 The descendijig branch passes downward and in- 
 ward between the sterno-mastoid and the platysma, is 
 reflected upward so as to form a loop, having its con- 
 cavity turned upward, perforates the platysma, and 
 then lies in contact with the skin, beneath which it 
 may be traced as far as opposite the os hyoides. 
 One of its twigs, which appears to me to be constant, having reached the side of the 
 median line, is reflected upward in front of the anterior jugular vein, ascends vertical- 
 ly, and may be traced into the skin of the supra-hyoid region. 
 
 The ascending branch, which sometimes arises by a common trunk with the auricular 
 nerve, immediately divides into four or five very slender and slightly waving filaments, 
 which, situated at first between the sterno-mastoid and the platysma, generally perfo- 
 rate the last-named muscle, to become sub-cutaneous ; two of these diverging filaments, 
 which remain subjacent to the platysma, are very slender, and run along the external 
 jugular vein, one in front of and the other behind that vessel. 
 
 Ail the other filaments pass upward and inward in contact with the skin, and subdi- 
 vide into a great number of filaments, which may be traced as far as the skin of the chin 
 and lower part of the cheek ; I have seen two of these filaments anastomose with the 
 facial nerve. It is important to observe, that the cervical filaments of the facial nerve 
 occupy a deeper plane than those of the superficial cervical nerve, and are separated 
 from these latter in front by the platysma. 
 
 The Ascending Branches. 
 
 The Auricular J^erve. 
 
 The auricular nerve (auricularis magnus, d, fig. 285), the ascending anterior branch of 
 the cervical plexus, arises from the second and third cervical nerves by a trunk which 
 is common to it and to the superficial cervical ; it emanates from the plexus immediate- 
 ly above the last-named nerve, hke which it embraces the posterior border of the sterno- 
 mastoid so as to form a loop with the convexity turned backward, and then passes up- 
 ward and a little forward between the platysma and the sterno-mastoid, and reaches the 
 anterior border of that muscle opposite the angle of the lower jaw. In this situation it 
 gives off" several facial or parotid filaments, and terminates by dividing into a superficial 
 and a deep branch. 
 
 The facial or parotid branches are very slender ; some of them pass between the parot- 
 id and the skin, with which they are in contact ; the others pass through the parotid 
 gland from behind forward, and from below upward, to be distributed to the skin of the 
 cheek ; I have traced them as far as the skin which covers the malar bone ; it has not 
 been shown that some of them terminate in the substance of the parotid, as has been 
 stated.* 
 
 The superficial auricular branch ascends vertically, in the substance of the very dense 
 
 * I have seen two of these parotid filaments terminate in a small abnormal ganglioii, from which other fil 
 aments were given off and distributed in the manner above described 
 
THE SUPRA-CLAVICULAR NERVES. 779 
 
 fibrous tissue which connects the parotid to the skin ; it gains the lower part of the 
 concha opposite to the anti-tragus, and then divides into several filaments, the distribu- 
 tion of which is remarkable : the largest passes above the lobule in the fissure between 
 the concha and the caudal extremity of the helix, and is distributed to the skin on the 
 concave surface of the auricle, and especially to the skin of the concha ; another fila- 
 ment turns round the margin of the auricle, and gains the groove of the helix, which it 
 follows even to its upper part. 
 
 The deep auricular branch, which may be called the antenor mastoid, perforates the 
 substance of the parotid gland, and gains the front of the mastoid process ; here it 
 crosses at an acute angle over the auricular branch of the facial nerve, which is more deep- 
 ly seated, and with which it anastomoses by a rather large branch ; it then passes be- 
 hind the posterior auricular muscle, and divides into two secondary branches : a poste- 
 rior, which passes upward and backward, and may be traced as far as the outer border 
 of the occipitalis muscle, where it anastomoses with a very delicate filament of the ex- 
 ternal occipital nerve ; and an anterior, which runs upon the upper part of the cranial 
 surface of the auricle. The superior filaments are reflected over the upper margin of 
 the auricle, and are distributed to the skin which covers its external or concave surface. 
 From what has been just stated, it follows that the auricularis magnus gives off no 
 
 . muscular filament. The posterior auricular and occipitalis muscles are supplied entire- 
 
 " ly from the auricular branch (c) of the facial nerve. 
 
 The Mastoid or External Occipital Kerve. 
 The mastoid or external occipital nerve (occipitalis minor, b), the posterior ascending 
 branch of the cervical plexus, rises from the second cervical nerve ; it comes off from 
 the plexus above the preceding nerve, describes a loop with the convexity turned up- 
 ward upon the posterior border of the sterno-mastoid, ascends almost vertically, parallel 
 to the great occipital nerve and to the posterior border of the sterno-mastoid, crosses 
 the posterior occipital attachments of that muscle, continues to ascend upon the occipi- 
 fe'tal region, and then upon the parietal region, and may be traced as far as opposite the 
 t anterior border of the parietal bone. During this course it is situated between the sple- 
 jiius and occipitalis muscles and epicranial aponeurosis on the one hand, and the skin on 
 "the other. 
 
 This nerve gives off in the occipital region some external branches, which are distrib- 
 uted to the skin, and anastomose with a filament of the auricular nerve, but none of them 
 pass to the auricle. The term occipito-auricular (Chauss.) is, therefore, not applicable to 
 it ; it should rather be called the external occipital (occipitalis minor, b),* to distinguish 
 . it from the internal occipital (occipitalis major, a), given off by the posterior branch of 
 the second cervical nerve. 
 
 It also supplies some internal branches, which anastomose several times with the in- 
 ternal occipital nerve, and are distributed to the skin. 
 
 It gives no filament to the occipitalis muscle, nor does it anastomose with the facial 
 nerve. The mastoid or external occipital nerve is essentially a cutaneous nerve. 
 
 We sometimes find a small supplementary branch between the great auricular and 
 .external occipital nerves, which runs parallel to them, and may be called the small mas- 
 .. jtoid nerve (c). 
 
 The Superficial Descending Branches. 
 The Supra-clavicular JVerves. 
 
 The Supra-clavicular Nerves {e,fig. 285 ; u,fig. 298). — The terminating branches of the 
 cervical plexus are two in number : one internal, or the supra-clavicular nerve, properly 
 so called ; the other external, or the acromial nerve ; they come off from the plexus at 
 the posterior border of the sterno mastoid, descend perpendicularly towards the clavicle, 
 and divide into several branches, which again subdivide before reaching that bone, so 
 that they cover the supra-clavicular triangle with their diverging filaments. All these 
 branches cross over the clavicle at almost regular intervals, and are lost upon the upper 
 and anterior part of the thorax. 
 
 The innermost or sternal branches cross very obliquely over the external jugular vein, 
 then over the clavicular and sternal attachments of the sterno-mastoid, and ramify in 
 the skin, where they may be traced as far as the median line. 
 
 The external or acromial branches pass obliquely over the external surface of the tra- 
 pezius, cross the outer end of the clavicle, and are distributed to the skin over the acro- 
 mion and the spine of the scapula. I have followed some filaments over the top of the 
 shoulder as far as the lower borders of the pectoralis major. 
 
 The intermediate or clavicular branches cross the clavicle at right angles, are in con- 
 tact with the skin upon the upper part of the thorax, and maybe traced to within a short 
 distance of the nipple, t 
 
 * The name mastoid branch is bad, for this branch has no relation with the mastoid process, 
 t Not unfrequcntly the supra-clavicular nerve passes through a foramen in the clavicle, at the junction of 
 the external third with the internal two thirds of that bone ; sometimes, instead of a bony canal, there is A 
 
t80 NEUROLOGY. 
 
 All these branches lie at first beneath the platysma, and then become sub- cutaneous. 
 A layer of fascia and the omo-hyoid muscle are interposed between them and the scaleni 
 muscles and brachial plexus. Some loose cellular tissue separates them from the clav- 
 icle, upon which they glide with the greatest freedom. 
 
 The Deep Descending Branches. 
 The Internal Descending Cervical J^erve. 
 
 The internal descending cervical nerve (before s, fig. 298), which is destined exclusively 
 for the muscles of the sub-hyoid region, may be considered as the inferior branch of the 
 bifurcation of the second cervical nerve, although the first and third nerves each give to 
 it a small re-enforcing filament. 
 
 It passes vertically downward, on the outer side of the internal jugular vein, along 
 which it runs, is joined on its inner side by a filament from the first cervical nerve, and 
 having reached a little below the middle of the neck, is reflected inward in front of the 
 internal jugular vein, and forms an anastomotic loop, which is sometimes plexiform, with 
 the descending branch (descendens noni, h) of the hypoglossal nerve ; this is a remark- 
 able anastomosis, and presents many varieties in its arrangement. The convexity of 
 this loop is turned downward, and from it arises a branch, which sometimes scarcely ex- 
 ceeds in size either of the formative branches of the loop, and which expands into sev- 
 eral filaments {g). One of these ascends and supplies the superior attachments of the 
 sterno-hyoid and omo-hyoid ; a transverse filament proceeds to the bodies of the sterno- 
 hyoid and sterno-thyroid muscles. Several filaments can be traced as far as the lower 
 part of the latter muscle, that is to say, down to opposite the second rib. The inferior 
 fleshy belly of the omo-hyoid is supplied by some twigs derived from the filaments which 
 enter its superior belly. 
 
 The Phretdc or Diaphragmatic Jferve. 
 
 The phrenic nerve {I, figs. 298, 302) is a branch derived from the fourth cervical nerve, 
 sometimes re-enforced by a very small filament from the third nerve, and almost al- 
 ways by a larger branch from the fifth.* Not unfrequently one of the formative branch- 
 es of the loop of the hypoglossal nerve just described joins the phrenic nerve. The right 
 and left phrenics are rarely of the same size. 
 
 After its origin, the phrenic nerve descends vertically in front of the inner border of 
 the scalenus anticus, with which it is held in contact by a fascia. It is round at first, 
 but becomes flattened as it passes between the sub-clavian vein and artery (I have seen 
 it pass in front of the vein), and is then inclined slightly inward, to enter the superior 
 orifice of the thorax. In the thorax (Z, fig. 302) it continues its vertical direction, runs 
 along the brachio-cephalic vein on the left side, and along the vena cava superior on the 
 right side, is then applied against the pericardium, to which it is bound down by the 
 pleura, and, having reached the diaphragm, ramifies in that muscle. It is accompanied 
 by the superior phrenic artery, which is a branch of the internal mammary, and the su- 
 perior phrenic vein. 
 
 The phrenic nerve gives off no branches in the thorax : at a short distance from its 
 origin, it anastomoses with the great sympathetic by a transverse branch : at the lower 
 part of the neck, it sometimes gives off a filament, which forms an anastomotic arch with 
 a branch derived from the fifth and sixth cervical nerves. I have never seen it com- 
 municate with the inferior cervical ganglion. 
 
 The distribution of this nerve in the diaphragm is curious. Some of its expanded, di- 
 verging, and generally very long filaments, run between the pleura and the diaphragm, 
 and enter the muscle from its upper surface ; others pass through the diaphragm, run 
 between it and the peritoneum, and enter the fleshy fibres from below ; they may be 
 traced as far as the costal attachments of the muscle. The right phrenic nerve termi- 
 nates by a transverse branch which passes behind the vena cava, and anastomoses with 
 certain transverse branches of the left phrenic, before it enters the pillars of the dia- 
 phragm, in which it terminates. I have never seen any filament of the phrenic nerv6 
 pass either to the oesophagus or to the solar plexus. 
 
 The Posterior Deep Cervical Branches. 
 These are, an anastomotic branch iv,fig. 298) from the cervical plexus to the spinal ac- 
 cessory nerve of Willis (t) ; it is of considerable size ; it comes off from the second nerve 
 at the same point as the external occipital nerve, and an2istomoses at an acute angle 
 
 tendinous arch upon the posterior border of the bone. In this case the clavicular branches are not scattered, 
 but closely aggregated together : the internal branches then pass horizontally inward between the clavicle and 
 the skin as far as the sternum ; and I have even seen a small twig enter the attachments of the pectoralis ma 
 jor. The external branches proceed horizontally outward upon the anterior border of the clavicle as far as the 
 acromion. 
 
 * The communication between the phrenic nerve and the fifth cervical nerve occurs in many different modeg. 
 Sometimes the phrenic supplies the communicating filament, instead of receiving it ; most commonly the 
 phrenic branch of the fifth arises by a common trunk with the nerve for the sub-clavius muscle, crosses in 
 front of the subclavian vein, between it and the cartilage of the first rib, with which it is in contact, and 
 •Mscs behind the internal mammary artery, to join the phrenic nerve at a very acute angle. 
 
THE BRACHIAL PLEXUS. 781 
 
 with the spinal accessory, between the cervical fasciculi of the splenius and the sterno- 
 mastoid. 
 
 Also, a ira.ncM.jor the trapezius, which arises from the third nerve, passes obliquely 
 downward and backward to the deep surface of the muscle, and anastomoses with the 
 spinal accessory of Willis, which it re-enforces, and with which it may be traced as far 
 as the lower angle of the muscle. 
 
 Lastly, the branches for the levator anguli scapulce and the rhomboideus ; these are rath- 
 er small branches, which arise from the back part of the third and fourth cervical nerves, 
 as they emerge from between the transverse processes of the vertebrae, pass obliquely 
 downward and backward, turn round the scalenus posticus in contact with it, and are 
 distributed to the levator anguli scapulsD and the upper part of the rhomboideus. The 
 same branches appear to supply both muscles. 
 
 The Anterior Branches of the Fifth, Sixth, Seventh, and Eighth Cervical 
 AND First Dorsal Nerves. 
 
 These branches are remarkable for their size, in which respect they surpass the pre- 
 ceding, and are almost all equal. On emerging from the inter-vertebral foramina, they 
 come into relation with the two scaleni muscles, which are separated from each other, 
 and sometimes are perforated by them ; they give off some very slender filaments to 
 these muscles, and, converging, anastomose together so as to form the brachial plexus, 
 from which all the nerves of the upper extremity are derived. 
 
 The Brachial Plexus. 
 
 The brachial plexus {h,jig. 268) extends obliquely from the lateral and inferior part ol 
 the neck to the cavity of the axilla, or, rather, to the inner side of the head of the hume- 
 rus, where it terminates by dividing into the nerves of the upper extremity ; it is formed 
 in the following manner : 
 
 The fifth and sixth cervical nerves (5, 6, fig. 286) unite at a short distance from the 
 scaleni, and the cord thus formed passes very obliquely downward and outward, and 
 then bifurcates. 
 
 Again, the eighth cervical (8) and the first dorsal (1) nerves unite immediately after 
 converging from the scaleni, and sometimes even between those muscles ; and the com- 
 mon cord passes almost horizontally outward, and bifurcates near the head of the humerus. 
 
 Between these two anastomotic cords is the seventh cervical nerve (7), which pur- 
 sues a much longer course than the others, and bifurcates on a level with the clavicle ; 
 the upper branch of its bifurcation joins the lower branch of the bifurcation of the first- 
 named cord, and its lower branch unites with the upper branch of the second-named cord. 
 
 From these several bifurcations and subsequent anastomoses, all of which take place 
 at very acute angles, results the interlacement known as the brachial plexus. 
 
 The brachial plexus is broad at its upper part, contracted in the middle, and broad 
 again at its lower part, on account of the divergence of its terminating branches ; it com- 
 municates with the cervical plexus by a considerable branch, which it receives from the 
 fourth cervical nerve, and also by the filament which it gives to the phrenic nerve ; it is 
 not so complicated but that the origins of the branches which emanate from it may be 
 traced ; I shall take care to do this for each nerve. 
 
 Relations. — At its origin it is situated between the scaleni, which cover it for a great- 
 er extent below than above. A very strong aponeurosis, which extends over it and the 
 scaleni also, completely isolates it from the surrounding parts. 
 
 Lower down, it is situated between the clavicle and sub-clavius muscle on the one 
 hand, and the first rib and upper part of the serratus magnus on the other. 
 
 Still lower, it is contained in the cavity of the axilla, separated from the pectoral- 
 is major in front by the costo-clavicular aponeurosis, and resting upon the scapulo-hu- 
 meral articulation behind, from which it is separated by the tendon of the sub-scapularis. 
 
 The following are its relations with the axillary artery : Between the scaleni and be- 
 low them, the artery is situated upon the same plane as the brachial plexus, and lies be- 
 tween the plexus and the first rib. Lower down it is placed on the anterior part of the 
 plexus ; at the lower extremity of the plexus it passes under the angle of union of the 
 two roots of the median nerve, by which it is embraced ; the axillary vein always lies 
 in front of the artery, and therefore has less direct rela- 
 tions with the plexus. 
 
 The branches of the brachial plexus may be divided 
 into the collateral and the terminal. 
 
 The terminal branches are five in nimiber, namely, the 
 internal cutaneous {g, fig. 286) and its accessory, the mus- 
 culo-cutaneous {b), the median (c), the radial or musculo- 
 spiral (/), and the ulnar {d) nerves.* 
 
 The collateral branches may be divided into those giv- 
 
 * I think it right to class the circumflex nerve among the collateral branches, and not, like most authors, 
 among the terminal branches of the plexus. 
 
^^2 NEUROLOGY. 
 
 en off above the clavicle, namely, the nerve for the suh-clavius, those for t^eJevator angu 
 li scapula and rhomboidcus, the posterior thoracic or nerve for the serratus magnus, the su- 
 pra-scapular nerve (a) or nerve for the supra- and infra-spinati muscles, and the superior sub- 
 scapular nerve ; those given off opposite the clavicle, namely, the thoracic branches ; and 
 those given off in the axilla, namely, the circumflex nerve (e) and the sub-scapular branches^ 
 which comprehend the nerve for the latissimus dorsi, the nerve for the teres major, and the 
 inferior scapular nerve. 
 
 One hranch only, namely, the nerve for the sub-clavius muscle, arises from the front 
 part of the brachial plexus : all the other collateral branches are given off from the back 
 of the plexus. 
 
 The Collateral Branches of the Brachial Plexus. 
 
 The Branches given off below the Clavicle. 
 
 The Nerve for the Sub-clavius Muscle. — This is a small but constant branch, which 
 comes off from the fifth cervical nerve, immediately before its junction with the sixth, 
 passes vertically downward in front of the sub-clavian artery, and then enters perpendic- 
 ularly into the middle of the sub-clavius muscle. 
 
 This small nerve, before reaciiing the sub-clavius, always gives off a phrenic branch, 
 which passes obliquely inward in front of the sub-clavian vein, and anastomoses with the 
 phrenic nerve. 
 
 The Nerve for the Levator Anguli Scapula. — This branch arises as frequently from the 
 cervical as from the brachial plexus ; in the former case, it arises from the fourth cervi- 
 cal nerve, in the latter from the fifth. It arises from the nerve immediately after its exit 
 from the canal of the transverse processes, turns round the scalenus posticus to gain 
 the deep surface 'oi the levator anguli scapulae, enters the muscle, supplies it with a 
 great number of filaments, and perforates it to reach the rhomboideus, under which it 
 passes. One of its terminating filaments anastomoses with a filament from the proper 
 nerve for the rhomboideus. 
 
 The Nerve for the Rhomboideus. — ^This arises from the fifth cervical nerve, immediately 
 below the preceding ; I have seen it arise by a common trunk with the superior branch^, 
 of origin of the nerve for the serratus magnus ; it passes downward and backward be- ^ 
 tween the scalenus posticus and the levator anguli scapulae, and then beneath the last- * 
 mentioned muscle, nearly as far as its scapular attachments, in order to get between the 
 rhomboideus and the ribs ; it may be traced as far as the lower part of that muscle. One 
 of its filaments perforates the rhomboideus, and anastomoses in the trapezius with the 
 posterior spinal nerves. 
 
 The Nerve for the Serratus Magnus {Posterior Thoracic Nerve of authors ; External Res- 
 piratory Nerve, Sir C. Bell). — This branch, which is very remarkable for the length of 
 its course, is derived from the fifth and sixth cervical nerves, immediately after their exit 
 from the canal of the transverse processes ; it arises by two roots, which are sometimes 
 equal and sometimes unequal in size ; it passes vertically downward behind the brachial 
 plexus and the axillary vessels, in front of the scalenus posticus, reaches the side of the 
 thorax (e', fig. 287), between the sub-scapularis and the serratus magnus, runs the whole 
 length of the last-named muscle, and ramifies in its lower portion. 
 
 During this course, it gives off a great number of filaments to the muscle : the lowest 
 of these may be traced as far as the lowest digitation. The branch which it gives to the . 
 upper part of the muscle is remarkable for its size. 
 
 I have seen a branch from the seventh cervical nerve join the external thoracic nerve ; 
 upon the upper part of the serratus magnus, so that this nerve would then be derived 
 from the fifth, sixth, and seventh cervical nerves. 
 
 The Supra-scapular Nerve, or Nerve for the Supra- and Infra-spinati Muscles. — This j 
 branch (a, fig. 286) is given off from the back part of the fifth cervical nerve at its junc- 
 tion with the sixth ; it passes obliquely backward, outward, and downward, dips beneath ,, 
 the trapezius, and then under the omo-hyoid, the direction of which it nearly follows, 
 and gradually increases in size as it approaches the coracoid notch of the scapula, and 
 passes by itself under the ligament which converts this notch into a foramen ; the supra- 
 scapular artery and vein, which had hitherto been in contact with the nerve, leave it op- 
 posite this notch to pass above the ligament, and then join it again in the supra-spinous 
 fossa. 
 
 The nerve then runs from before backward in the supra-spinous fossa, protected by a .^ 
 thick fibrous lamella, reaches the free concave border of the spine of the scapula, against" 
 which it is held by a fibrous band, is then reflected inward and downward over this con- ,j 
 cave border to gain the infra-spinous fossa, and immediately divides into two branches, ,.^ 
 one of which spreads out in the upper part, and the other in the lower part of the infra- ,^ 
 spinatus muscle. 
 
 During its course through the supra-spinous fossa, the supra-scapular nerve gives off 
 two supra-spinous branches, one of which is detached opposite the coracoid notch, and 
 the other upon the spine of the scapula. They both enter the supra-spinatus muscle. » 
 
BRANCHES BELOW THE CLAVICLE. 783 
 
 The supra-scapular nerve is exclusively destined for the supra- and infra-spinati mus- 
 cles. It gives no filament to the sub-scapularis. 
 
 The Superior Sub-scapular Nerve. — This is a very small branch which arises imme- 
 diately above the clavicle, and passes downward and forward to reach the upper border 
 of the sub-scapularis, and then enters that muscle. 
 
 The Branches given off opposite to the Clavicle. 
 
 These, which are named the thoracic branches,* are generally two in number, one an- 
 terior, the other ;?os^mor : they arise from the anterior part -of the brachial plexus, oppo- 
 site the sub-clavius muscle. The anterior branch, or nerve for the pectoralis major, which 
 is the larger, passes downward and forward between the sub-clavius muscle and the sub- 
 clavian vein, and divides into two branches : an external, or anastomotic, which some- 
 times arises directly from the brachiad plexus, and forms a loop around the axillary ar- 
 tery, by anastomosing with the posterior thoracic branch ; and an internal, which runs 
 along the deep surface of the pectoralis major, and expands into a great number of re- 
 markably long and slender filaments, which enter the muscle very obliquely, and may be 
 traced as far as its sternal attachments. A very slender filciment is constantly foimd 
 running along the clavicle. 
 
 The posterior thoracic branch, or nerve for the pectoralis miner, passes behind the axillary 
 artery, below which it curves forward, to form, with the external branch of the anterior 
 thoracic, the anastomotic loop of which I have already spoken. From this loop or arch, 
 in forming which the nervous filaments are separated from each other, two sets of 
 branches proceed : the one set runs between the pectoralis major and minor, closely 
 applied to the former muscle, which they then enter, diverging to its lowest part ; the 
 others pass beneath the pectoralis minor, and penetrate its deep surface ; some of them 
 pass obliquely through this muscle and join the anterior thoracic branches in the pecto- 
 ralis major. 
 
 The Branches given off below the Clavicle. 
 
 The Axillary or Circumflex Nerve. — This is no less remarkable for its great size, which 
 has led some anatomists to regard it as a terminal branch of the brachial plexus, than 
 for its reflected course : it comes off from the back of the plexus, behind the musculo- 
 spiral nerve, or, rather, the circumflex and musculo-spiral nerves (e and f, fig. 286) ap- 
 pear to be the two divisions of a trunk formed by filaments from the five branches of the 
 brachial plexus. 
 
 Immediately after its origin, the circumflex nerve passes downward and outward (g, 
 fig. 288) in front of the sub-scapularis, which separates it from the shoulder-joint, turns 
 obliquely round the lower border of that muscle, round the back part of the articulation, 
 and, lastly, round the surgical neck of the humerus, is then reflected upward, so as to de- 
 scribe a curve with the concavity turned in the same direction, and terminates by ram- 
 ifying in the deltoid. 
 
 During this curved course, the circumflex nerve, accompanied by the posterior cir- 
 cumflex vessels, passes at first between the sub-scapularis and the teres major, then be- 
 low the teres minor, on the outer side of the long head of the triceps (i. e., next to the 
 bone), and then lies in contact with the deep surface of the deltoid, against which it is 
 held by a very dense layer of fascia. 
 
 The relation of the circumflex nerve to the articulation explains the possible occur- 
 rence of laceration of this nerve in luxations of the humerus downward. 
 
 The collateral branches of the circumflex nerve are three in number. One branch almost 
 always goes to the sub-scapularis. I have already said that the sub-scapular nerves 
 might be regarded as branches of the circumflex. 
 
 As it turns round the lower border of the sub-scapularis, the circumflex gives off a 
 branch for the teres minor and the cutaneous branch of the shoulder. 
 
 The nerce for the teres minor enters that muscle by its lower border ; it almost always 
 arises by a common trunk with a deltoid branch, which runs upward and backward to 
 supply the back part of the deltoid muscle. 
 
 The cutaneous nerve of the shoulder frequently arises by a common trunk with the two 
 preceding, and, in this case, the circumflex nerve appears to bifurcate ; it passes under 
 the posterior border of the deltoid, then lies in contact with the skin covering the back 
 part of the top of the shoulder, and divides into diverging branches, some ascending, oth- 
 ers descending, and others running horizontally. A second, and sometimes a third cu- 
 taneous branch perforates the fleshy fibres of the deltoid, and is distributed to the corre- 
 sponding skin. 
 
 The terminal or deltoid branches of the circumflex nerve are given off as that nerve is turn ■ 
 ing round the neck of the humerus, in which situation it divides into several diverging 
 branches, the superior of which ascends, and appears like the continuation of the nerve, 
 while the others descend, and may be traced as far as the insertion of the muscle into the 
 humerus. 
 
 * The anterior thoracic nerves of those who name the nerve for the serratus magnus the posterior thoracic 
 
784 
 
 NEUROLOGY. 
 
 Tlie Sub-scapular Nerves. — The nerve for the latissimns dor si is the largest of the nerves 
 generally described as the sub-scapular ; it comes off at an acute angle from the inside of 
 the circumflex nerve, and descends vertically in the midst of the cellular tissue of the 
 axilla, between the sub-scapularis and serratus magnus, parallel to the external thoracic 
 nerve, which it greatly resembles in size and direction as well as in its length ; it then 
 passes in front of the latissimus dorsi, reaches its outer border, and may be traced down 
 to the lower part of that muscle. 
 
 The nerve for the teres major arises at a very acute angle from the preceding nerve, to 
 the inner side of which it runs ; it passes to the sub-scapularis, turns round its outer bor- 
 der, and enters the anterior surface of the teres major by a great number of filaments. 
 
 The inferior sub-scapular nerve {I, Jig- 288) is sometimes multiple, and presents many 
 varieties in its origin and number. Thus, it sometimes curves directly from the brachial 
 plexus ; sometimes from a common tnmk with the circumflex nerve. Again, it often 
 arises by a common trunk with the nerve for the teres major. Whatever be its origin, 
 and whether it be single or multiple, it enters immediately into the sub-scapularis, and 
 terminates there. 
 
 We have seen that a small branch given off from the brachial plexus above the clavi- 
 cle, the superior sub-scapular nerve, enters the same muscle at its upper border. 
 
 The Terminal Branches op the Brachial Plexus. 
 The Internal Cutaneous Jferve and its Accessory. 
 ^- 287. The internal cutaneous nerve (g, fig. 286), the most internal 
 
 and the smallest of the terminal branches of the brachial plex- 
 us, arises by a common trunk with the ulnar nerve (</) and 
 the internal root of the median (c) : concealed at first by the 
 axillary artery, it descends vertically (a, Jig. 288) to the inner 
 side of the median nerve, and in front of the basilic vein : at 
 the upper part of its course it lies beneath the fascia, but it 
 becomes sub-cutaneous at the same time as the basilic vein 
 {b, fig. 287), and is then separated from the median nerve by 
 the brachial aponeurosis ; at the middle of the arm, it divides 
 into two terminal branches, an external, anterior or ulnar, and 
 an internal, posterior or cpitrochlear. The internal cutaneous 
 gives off only one branch during its course along the arm, 
 namely, a cutaneous branch, which varies in size as well as in 
 the situation at which it is given off: this cutaneous branch 
 arises in the cavity of the axilla, often anastomoses with an 
 intercostal nerve, is applied against the skin on the inner as- 
 pect of the arm, and may be traced as far as the elbow.* 
 
 Terminal Branches. — The anterior, external or ulnar branch, 
 which is the larger, continues in the vertical direction of the 
 trunk of the nerve, and divides into two branches, which de- 
 scend in front of the elbow-joint, sometimes before, and some- 
 times behind the median basihc vein (e), and again subdivide 
 into a great number of filaments which diverge, and are ar- 
 ranged in the following manner : the internal filaments pass 
 obliquely downward, inward, and backward, crossing the ul- 
 nar vein (m), and then the ulna, and supply the skin covering 
 the inner and back part of the forearm ; they can be traced 
 nearly as far as the region of the carpus : the external fila- 
 ment, which might be called median, because it follows the 
 median vein, descends vertically, and may be traced as far as 
 the upper part of the palm of the hand ; one of these filaments 
 always anastomoses with a twig from the ulnar nerve at the 
 lower part of the forearm. 
 
 The posterior, internal or epitrochlear branch (g), descends ver- 
 tically behind the median basilic vein, in front of the epitroch- 
 lea, and then below it, so as to embrace it in a sort of loop ; 
 it then passes very obliquely downward and backward, cross- 
 es the ulna below the olecranon, gains the dorsal aspect of 
 the forearm, and runs vertically (a, fig. 289) down to the wrist. 
 Around the epitrochlea, this internal branch gives off several 
 branches, which ramify upon the skin that covers the inner 
 side of the elbow-joint : one of these branches is reflected up- 
 ward between the epitrochlea and the olecranon, and anasto- 
 moses with the accessory nerve of the internal cutaneous. 
 
 * I have always found a remarkably long and slender filament arising from the internal cutaneous nerve at 
 the upper part of the arm ; it runs along that nerve, passes beneath the basilic vein, and then lies in contact with 
 the fascia, which it perforates near the epitrochlea, and is lost upon the synovial membrane of the elbow-joint. 
 
THE MUSCULO-CUTANEOUS NEEVE. 1^5 
 
 Frequently, before reaching the epitrochlea, this branch has already given off a twig 
 which anastomoses with the same nerve. 
 
 Summary. — The internal cutaneous nerve, then, is exclusively intended for the skin. It 
 only gives one small branch to the arm : its other divisions are intended for the forearm. 
 One of them belongs to the dorsal, and the other to the internal aspect. 
 
 The Accessory Nerve of the Internal Cutaneous. — I have applied this term to a small 
 branch (cutaneus minor internus, Wrisberg), which it is difficult to discover, and which 
 would be more properly classed among the collateral than the terminal branches of the 
 brachial plexus : it arises above and sometimes below the clavicle, from the back part 
 of the nervous cord formed by the junction of the eighth cervical and first dorsal nerves : 
 it passes downward upon the sides of the thorax, and divides into two branches, an ex- 
 ternal and an internal. 
 
 The external branch (a', fig. 287), which is the smaller one, passes vertically downward, 
 and crosses the conjoined tendons of the teres major and latissimus dorsi at right an- 
 gles ; it lies in contact with the skin covering the inner and back part of the arm, and 
 may be traced as low as the elbow. 
 
 The internal branch (c) anastomoses with the second intercostal nerve, descends ver- 
 tically, crossing the conjoined tendons of the latissimus dorsi and teres major, becomes 
 applied to the skin, and divides into several very slender filaments, which correspond to 
 the internal, anterior, and posterior regions of the arm, and may be traced as far as the 
 region of the elbow ; one of these filaments anastomoses with the internal cutaneous.* 
 
 The Musculo-cutaneous JSTerve. 
 
 The musculo-cuta?ieous nerve (b, fig. 286), the most external of the terminal branches 
 of the brachial plexus, and, with the exception of the internal cutaneous, the smallest, 
 arises by a common trunk with the external root of the median nerve (c), passes down- 
 ward and outward, in front of the humeral insertion of the sub-scapularis, and on the 
 inner side of the coraco-brachialis, which is perforated by it, and is therefore called the 
 per/orated muscle of Casserius.f After emerging from the muscle, through which it passes 
 very obliquely,t the musculo-cutaneous nerve {h,fig. 288) is situated between the biceps 
 and the brachialis anticus, continues its oblique course, escapes from beneath the outer 
 border of the tendon of the biceps, and then becomes sub-cutaneous. 
 
 During its course along the arm it gives off the following branches 
 
 The branches for the coraco-brachialis are two in number : one superior, which enters the 
 upper part of this muscle, and is then lost in the short head of the biceps ; the other in- 
 ferior, which, in some subjects, after having furnished a certain number of filaments to the 
 coraco-brachialis, becomes applied to the trunk of the musculo-cutaneous nerve itself. 
 
 The branches for the biceps are very numerous : not uncommonly they arise by a com- 
 mon trunk, which then appears to result from the bifurcation of the musculo-cutaneous. 
 One of these branches perforates the biceps, and passes transversely outward to reach 
 the elbow-joint, to which it is distributed. 
 
 The branches for the brachialis anticus almost always arise by a large common trunk 
 which appears to result from a farther bifurcation of the nerve, already diminished one 
 half, after it has supplied the branches for the biceps. While these last-named branches 
 enter the posterior surface of the corresponding muscle, the branches for the brachialis 
 anticus penetrate that muscle by its anterior surface. 
 
 After having given off all these muscular branches, the musculo-cutaneous nerve, re- 
 duced to a fourth or a fifth of its original size, is distributed entirely to the skin ; it passes 
 vertically downward in front of the elbow-joint, behind the median cephalic vein {a, fig. 
 287), and divides into two terminal branches, of which the internal (A) runs along the 
 inner, and the external along the outer side of the radial vein. 
 
 These two branches, during their course along the forearm, lie between the fascia of 
 the forearm and the superficial fascia ; they gradually diminish in size as they give off 
 their filaments to the skin, and terminate in the following manner : 
 
 The external branch passes to the dorsal surface of the forearm, and may be traced as 
 far as the skin which covers the carpus. 
 
 The internal branch has a more extensive distribution ; it anastomoses with a branch 
 of the radial nerve at the lower part of the forearm, and gives off a deep or articular 
 branch, which divides into several twigs that surround the radial artery. One of these 
 twigs expands into a number of filaments which enter the fore part of the radio-carpal 
 articulation ; the others accompany the radial artery in its oblique course upon the outer 
 side of the carpus, and then spread out to terminate on the back part of the synovial 
 membrane of the wrist-joint. After having given off this very remarkable articular 
 branch,!^ the internal terminal division of the musculo-cutaneous nerve passes in front 
 
 * [And with the internal cutaneous branch of the musculo-spiral nerve.] 
 t [The nerve is also called perforans Casserii.l 
 
 X Not unfrequeutly the nerve does not perforate the coraco-brachialis. [It sometimes has an anastomosis 
 iMth the median nerve after emerging from the coraco-brachialis.] 
 t In one subject, the articular filaments had some gangliform enlargements on their sides precisely similar 
 
 5G^ 
 
me 
 
 NEUROLOGY. 
 
 of the tendons of the extensor brevis poUicis and abductor longus poUicis, in front of and 
 more superficially than the corresponding branch of the radial nerve, and then divides 
 into several twigs, which are intended for the skin of the thenar eminence. One of 
 these branches, which runs along the outer side of that eminence, may be traced into 
 the skin upon the first phalanx of the thumb. 
 
 Summary. — The musculo-cutaneous nerve, then, supplies certain muscular branches, 
 which belong exclusively to the coraco-brachialis, the biceps, and the brachialis anticus ; 
 the section of this nerve would, therefore, destroy the power of flexing the forearm : 
 certain cutaneous branches to the skin on the outer side of the forearm and hand ; and, 
 lastly, some articular branches to the elbow and to the wrist. 
 
 The Median Jferve. 
 The median nerve (c. Jig. 286), one of the terminal branches of the brachial plexus, 
 arises from the plexus by two very distinct roots between the musculo-cutaneous (i) on 
 the outer side, and the ulnar nerve {d) on the inner.* The internal root arises from a 
 nervous cord which is common to it, to the ulnar, and to the internal cutaneous (g). 
 The external root arises from a cord common to it and to the musculo-cutaneous. The 
 axillary artery passes between these two roots. 
 
 The trunk resulting from the union of these two roots is situated on the inner side 
 of the axillary artery ; it is at first grooved to receive the inner half of tho artery, but it 
 soon forms a rounded cord, proceeds vertically downward (c. Jig. 288), gains the middle 
 and fore part of the elbow-joint, dips between the muscles on the anterior region of the 
 forearm (rf), and passes behind the annular ligament to enter the palm of the hand (r), 
 where it terminates by dividing into six branches. We shall examine it in the arm, the 
 forearm, and the hand. 
 
 •Pifi". 288. In the Arm. 
 
 The median nerve (c), which is straight and vertical, 
 and the satellite nerve of the brachial artery, passes some- 
 what obliquely downward, forward, and outward, to the 
 middle and fore part of the elbow-joint. 
 
 Relations. — On the inner side it is sub-aponeurotic, so 
 that when the arm is held away from the side, and the 
 forearm is extended upon the arm, it projects below the 
 skin like a tense cord, which is very distinctly seen in 
 emaciated subjects. 
 
 On the outside, it corresponds at first to the brachialis 
 anticus, and is then received in the sort of groove formed 
 between the inner border of the biceps and the brachialis 
 anticus. 
 
 In front, it is covered by the inner border of the biceps, 
 excepting in emaciated subjects. 
 
 Behind, it is in relation with the ulnar nerve (/), and then 
 with the brachialis anticus. 
 
 Its relations with the brachial artery are of the greatest 
 importance, in reference to the application of a ligature to 
 that vessel. The nerve is at first situated to the outer or 
 radial side of the axillary artery, but soon passes in front of 
 the vessel, and then it crosses over slightly, so that at the 
 bend of the elbow it is situated about two lines to the inner 
 or ulnar side of the artery. This last relation is not con- 
 stant : I have seen the nerve on the outer side of the artery 
 at the bend of the elbow. 
 
 The following are its relations with the other nerves : the 
 internal cutaneous nerve runs along its inner side, at first 
 immediately in contact with it, and then separated from it 
 by the fascia of the arm. 
 
 The ulnar nerve runs behind it in the upper third of the 
 arm, and is then separated from it, so that the two nerves 
 bound the sides of a triangular interval, the base of which 
 is below and the apex above. 
 
 The median nerve does not give any branch in the 
 arm.t 
 
 to those which are met with on the cutaneous nerves in the palm of the 
 hand ; the articular filaments, moreover, have almost always the grayish 
 aspect of the nerves of organic life. . , , ^, , 
 
 * These two roots of the median nerve, when united to the raiisculo-cu 
 taneous and the ulnar, represent very nearly a capital M. ^ot unfre 
 quently there is a third internal root for the median nerve. 
 
 t [Except, occasionally, an anastomotic branch to the musculo-cutane 
 ous, after the latter has emerged from the coraco-brachialis.] 
 
THE MEDIAN NERVE IN THE FOREARM AND HAND. 787 
 
 In the Forearm. 
 TTie median nerve, like the brachial artery, to the inner side of which it is generally 
 situated, passes beneath the tendinous expansion of the biceps, and is separated from 
 the elbow-joint by the brachialis anticus. 
 
 It almost always perforates the pronator teres in such a manner as to leave only a 
 very small tongue of fleshy fibres behind it;* it then passes (rf, fig. 288) between the 
 flexor sublimis and flexor profundus digitorum, opposite the cellular interval between 
 the latter muscle and the flexor longus poUicis : at the lower part of the forearm it runs 
 along the outer border of the flexor sublimis, where it might be easily exposed between 
 the tendon of the palmaris longus on the inside, and of the flexor carpi radialis on the 
 outside. I have seen this nerve perforate the upper part of the flexor sublimis, which 
 formed a sheath for it. 
 
 Branches. — These are muscular, excepting the palmar cutaneous, which arises at the 
 lower part of the forearm : they supply all the muscles of the anterior region of the fore- 
 arm except a part of the flexor profundus, and the whole of the flexor carpi ulnaris, 
 which receive branches from the ulnar nerve. Lastly, with the exception of the palmar 
 cutaneous, the branches arise near the bend of the elbow. 
 
 The branch for the ^pronator teres comes off from the anterior part of the median nerve, 
 a little above the elbow-joint, and passes downward to enter the substance of the mus- 
 cle. It gives off several articular filaments, which dip from before backward, around the 
 termination of the brachial artery and the commencement of the radial and ulnar arter- 
 ies, form loops with their concavities turned upward in the angle of bifurcation of the 
 brachial, and then enter the articulation. 
 
 The other collateral branches of the median in the forearm arise from its posterioi 
 aspect : they are the branch for the superficial layer of muscles, which arises opposite the 
 elbow-joint, and then divides successively into several others, which enter the pronator 
 teres, the flexor carpi radialis, the palmaris longus, and the flexor sublimis. The filaments 
 for the flexor sublimis are remarkably slender, and are reflected upward below the epi- 
 trochlea : they belong to the upper part only of this muscle, which is also supplied by 
 two or three other branches, given off in succession from the median, a little below the 
 bend of the elbow. 
 
 The branch for the deep layer of muscles is a large trunk, which soon divides into sev- 
 eral branches, viz., one external, for the flexor longus pollicis, the upper extremity of 
 which it enters ; two internal, which enter the flexor profundus, but only supply its inner 
 half, the other half receiving its nerves from the ulnar ;t and a middle branch, the inter- 
 osseous nerve (e), which requires a particular description. It passes vertically downward, 
 in front of the interosseous ligament, between the flexor profundus and the flexor lon- 
 gus pollicis, to both of which it gives several filaments ; having reached the upper bor- 
 ders of the pronator quadratus, it passes behind that muscle and divides into a great 
 number of filaments, some of which penetrate the muscle from behind, while others de 
 scend to gain the lower part of the muscle. I have seen the interosseous nerve per- 
 forate the interosseous ligament, run a very short distance upon its posterior surface, 
 then pass through it again, and ramify in the pronator muscle. 
 
 The palmar cutaneous branch (i, fig. 287) comes off from the median nerve opposite the 
 junction of the three upper fourths with the lower fourth of the forearm, runs along the 
 median nerve, and divides into two branches, which perforate the fascia of the forearm 
 immediately above the annular ligament. The external branch is the smaller, and cross- 
 es obliquely over the tendon of the flexor carpi radialis, and terminates in the skin upon 
 the ball of the thumb ;t the internal branch, which is larger, descends vertically in front 
 of the annular ligament and beneath the skin, from which it is separated by a layer of 
 adipose tissue, and is lost in the palm of the hand, much sooner than might be expected 
 from its size ;^ it can scarcely be traced as far as the middle of the palm. 
 
 In the Hand. 
 The median nerve, while passing behind the annular ligament of the carpus, becomes 
 considerably wider and flattened ; it might even be said to increase gradually in size. 
 Immediately after it has passed below the ligament, still flattened out, it divides (r) into 
 two branches, one internal, the other external, which are themselves subdivided ; the in- 
 ternal into two, and the external into four branches, so that in aU there are six terminal 
 branches. 
 
 * In one case, in which the humeral attachments of the pronator teres were as high as those of the supina- 
 tor longus, the median nerve passed through the highest attachments of the pronator teres, and was situated 
 between the brachialis anticus and that muscle, which also covered it at the bend of the elbow; in this same 
 case, the brachial artery divided into the radial and ulnar at the middle of the arm ; and the ulnar artery ap- 
 plied against the nerve had the same relations as the brachial artery in ordinary cases. 
 
 t All the deep branches may be traced as far as the periosteum of the bones of tlie forearm. [Some of them 
 have been seen to communicate with filaments of the ulnar nerve.] 
 
 t [This tirauch anastomoses with the terminal cutaneous division of the musculo-spiral or radial nerve.] 
 
 ^ This sudden mode of termination is common to all nerves of sensation, which are often Uist almost imme- 
 diately in the skin ; the nerves of motion, on the other hand, run a very h)nsr course as filaments licforf thev 
 terminate in the muscles. 
 
788 NEUROLOGY. 
 
 Tho, terminal branches of the median nerve. Of these one only is muscular, and oe- 
 longs to the muscles of the ball of the thumb ; the other five are intended for the integ- 
 uments of the fingers, of vi^hich they form the palmar collateral nerves. 
 
 The branch for the muscles of the ball of the thumb is a recurrent nerve ; it arises from 
 the front of the median, passes upward and outward, forming a horizontal curve with 
 the concavity turned upward, perforates the superficial layers of the flexor brevis, im- 
 mediately gives off a descending branch to that muscle, and, continuing to ascend itself, 
 is divided almost equally between the abductor brevis and the opponens pollicis. 
 
 The External Collateral Branch of the Thumb* — This nerve passes obliquely down- 
 ward and outward, on the inner side of the tendon of the flexor longus pollicis, crosses 
 the metacarpo-phalangal articulation, to gain the external border of the anterior surface 
 of the thumb, and, running along the outer side of the tendon of the long flexor, arrives 
 at the ungual phalanx. On this phalanx, it divides into two branches, a dorsal or ungiud, 
 properly so called, which turns round the side of the phalanx, anastomoses with the dor- 
 sal collateral branches of the radial nerve, and is distributed to the dermis beneath the 
 nail ; and a palmar, which is lost in the skin covering the pulp of the thumb. Some of 
 these latter filaments turn round the tip of the phalanx, and are distributed to the skin 
 beneath the nail. None of the filaments of the external collateral branch anastomose 
 with those of the internal collateral. 
 
 The internal collateral branch for the thumb is less oblique in its course and larger than 
 the preceding ; it nins along the first interosseous space in front of the adductor pollicis, 
 and reaches the inner side of the anterior surface of the thumb, along the tendon of the 
 long flexor, and terminates like the preceding branch. This branch gives oflf a twig to 
 the adductor pollicis. 
 
 The external collateral branch for the index finger sometimes arises by a common trunk 
 with the preceding ; it runs along the first interosseous space in front of the adductor 
 pollicis, on the outer border of the first lumbricalis muscle, to which it gives a filament, 
 and then divides into two branches, a dorsal and a palmar : the dorsal branch, which is 
 the smaller, passes backward and downward, along the outer border of the first phalanx, 
 unites with the dorsal collateral branch derived from the radial nerve, gains the poste- 
 rior surface of the second phalanx, and terminates upon the third, near the nail. The 
 palmar branch, which forms the true continuation of the trunk of the nerve, is arranged 
 like the corresponding nerve of the thumb, and does not anastomose with the internal 
 collateral branch. 
 
 The common trunk of the internal collateral branch of the index finger, and external collat- 
 eral branch of the middle finger, passes vertically downward, in front of the second inter- 
 osseous space, at the middle of which it divides into two branches, one of which forms 
 the internal collateral branch of the index finger, and the other the external collateral branch 
 of the middle finger. These collateral nerves, like the preceding, divide into a dorsal and 
 a palmar branch, the latter of which again subdivides into a sub-ungual branch and a 
 branch for the pulp of the finger. 
 
 Tlie common trunk of these two collateral nerves, before bifurcating, gives ofT a twig 
 to the second lumbricalis. 
 
 The common trunk of the internal collateral branch of the middle finger, and external col- 
 lateral branch of the ring finger, passes somewhat obliquely inward, in front of the third 
 interosseous space, and is distributed in the same way as the preceding branches ; be- 
 fore bifurcating, it sometimes gives a twig to the third lumbricalis ; it receives an anas- 
 tomotic filament from the ulnar nerve. The bifurcation of this sixth branch takes place 
 a little below the metacarpo-phalangal articulations. 
 
 Relations. — The following are the relations of the palmar and digital portions of the 
 median nerve : 
 
 Behind the anterior annular ligament of the carpus, the median nerve is situated on the 
 outer side of the tendons of the flexor sublimis and in front of those of the flexor pro- 
 fundus : like the tendons among which it is placed, it is at first covered by the synovial 
 membrane in front and behind. 
 
 In the palm of the hand, the median nerve is covered by the palmar fascia, and is situ- 
 ated in front of all the flexor tendons. The superficial palmar arch lies in front of it, 
 and crosses at right angles over its three internal branches. 
 
 The collateral nerves of the fingers accompany the collateral vessels, and pass with them 
 from the palm of the hand opposite the intervals between the metacarpo-phalangal ar- 
 ticulations. Like the vessels which run along their outer side, these nerves occupy the 
 borders of the palmar aspect of the fingers, one on each side of the tendinous groove. 
 
 Summary. — From what has been stated, it follows, then, that the median nerve gives 
 off no branch in the arm ;t that, in the forearm, it gives no nerve to the skin, but sup- 
 plies all the muscles of the anterior region, excepting the flexor carpi ulnaris and the 
 inner half of the flexor profundus, which we shall see are supplied by the ulnar ; and, 
 lastly, that, in the hand, it supplies the cutaneous nerves of the palm, the external and 
 
 * I have seen it arise after the third branch, and upon a plane anterior to that branch, tlie oriijin of" which 
 It then crossed. t See note, p. 7£6. 
 
THE ULNAR NERVE IN THE ARM AND FOREARM. 789 
 
 internal collateral nerves of the thumb, index finger, and middle fingers, and the exter- 
 nal collateral nerve of the ring finger, and also the muscular nerves of the ball of the 
 thumb and the nerves of the two outer lumbricales, and sometimes that of the third 
 lumbricalis. 
 
 The Ulnar Jferve. 
 
 The ulnar nerve {d, fig. 286), a little smaller than the preceding, behind which it is 
 situated, arises by a trunk which is common to it, to the internal root of the median 
 nerve (c), and to the internal cutaneous nerve (g-) ; it passes vertically downward be- 
 hind, and at first in contact with the median, but soon leaves that nerve, and runs some- 
 what backward (/, fig. 288), while the median is directed forward and outward ; it per- 
 forates the upper fibres of the internal head of the triceps, and enters the sheath of that 
 muscle, behind the internal inter-muscular septum. It thus gains the groove between 
 the inner condyle of the humerus and the olecranon, passes between the two origins of 
 the flexor carpi ulnaris, and is reflected from behind forward in this groove, and then 
 upon the inner side of the coronoid process : having thus reached the anterior aspect of 
 the forearm, it passes vertically downward (/) between the flexor carpi ulnaris and the 
 flexor profundus, and gains the palm of the hand (s), where it divides into its terminal 
 branches. As with the median nerve, we shall examine the ulnar in succession in the 
 arm, the forearm, and the hand. 
 
 In the Arm. 
 
 The most important relation of this nerve (/) in the arm is that at its upper part with 
 the median nerve and brachial artery. It runs along the inner side of the artery, while 
 the median nerve is situated in front of the vessel, or, rather, the artery is situated be- 
 tween the median and ulnar nerves, so that it may be exposed immediately below the 
 axilla, by separating these two nerves. 
 
 The ulnar nerve gives off no branch in the arm ; the error of those who have stated 
 the contrary has arisen from the fact that the branch given from the musculo-spiral 
 nerve to the internal portion of the triceps lies in contact with the ulnar nerve for a 
 great part of its extent, so that it would seem at first sight to come off from it. 
 
 The Forearm. 
 
 The ulnar nerve in the forearm (/) is at first covered by the fleshy belly of the flexor 
 carpi ulnaris, which separates it from the skin ; it becomes sub-aponeurotic below, where 
 the fleshy fibres of that muscle cease, and is found between the tendon of the flexor carpi 
 ulnaris on its inner side, and those of the flexor sublimis on its outer side. 
 
 Its relation with the ulnar artery is remarkable. This vessel describes a curve so as 
 to reach the outer or radial side of the nerve ; but the nerve and artery are in contact 
 in the lower third only of the forearm. 
 
 The branches of this nerve in the forearm are somewhat numerous. Between the in- 
 ternal condyle and the olecranon, the ulnar nerve gives several very delicate articular 
 filaments, which pass into the elbow-joint ; it also gives off branches for the flexor carpi 
 ulnaris ; one of which is very large, and may be traced as far as the lower part of the 
 fleshy belly of the muscle. 
 
 After its reflection, the ulnar nerve gives a branch to the flexor profundus digitorum, 
 subdivides, and enters the substance of that muscle. Its divisions run upon the anterior 
 surface of the muscle before penetrating it. This branch is intended for the two inner 
 portions of the flexor profundus, the two outer portions receiving their filaments from 
 the median nerve.* 
 
 At the middle of the forearm, a small, long, and slender branch is given off from the 
 anterior part of the ulnar nerve, and divides into two filaments, one of which follows the 
 ulnar artery (filament of the ulnar artery), while the other perforates the fascia of the fore- 
 arm, and anastomoses with the internal cutaneous nerve {anastomotic filament). 
 
 The internal dorsal nerve of the hand (x) is the largest of the branches of the ulnar 
 nerve, so that it might be regarded as a terminal branch of that nerve ; it is exclusively 
 intended for the skin of the dorsal region of the hand. It comes off opposite the junc- 
 tion of the two upper thirds with the lower third of the forearm, passes obliquely down- 
 ward, backward, and inward between the ulna, over which it crosses, and the flexor car- 
 pi ulnaris, and emerges (x, fig. 289) from below the tendon of that muscle, a very short 
 distance above the lower end of the ulna. It then descends vertically between the skin 
 and that part of the bone, runs along the inner side of the carpus, and divides into two 
 dorsal branches, an internal and an external. 
 
 The internal dorsal branch is the smaller ; it runs along the ulnar border of the fifth 
 metacarpal bone, and along the internal or ulnar side of the dorsal region of the little 
 finger, of which it forms the internal collateral dorsal nerve. 
 
 The external dorsal branch is much larger ; it first gives off a small anastomotic ttmg, 
 which crosses obliquely over the metacarpal bone, and anastomoses with a correspond- 
 
 ^ [The 'Inarmay communicate in this position with filauuiit^ pf the antenor interosseous.! 
 
"m 
 
 NEUROLOGY. 
 
 ingly oblique branch from the radial nerve, opposite the lower part of the second interos 
 seous space. It then descends vertically along the fourth interosseous space, and di- 
 vides into two secondary branches, which again subdivide to form the dorsal collateral 
 nerves, in the following manner : one forms the external collateral nerve of the little finger, 
 and the internal collateral nerve of the ring finger ; and the other the external collateral 
 nerve of the ring finger, and the internal collateral nerve of the middle finger.'^ 
 
 In the Hand. 
 
 The ulnar nerve enters the palm of the hand {s,fig. 288), not by passing behind the an- 
 terior annular ligament, but in a special sheath, which is common to it and to the ulnar 
 artery, is situated on the inner side of the annular ligament, and has the pisiform bone 
 to its inner side, and unciform bone to its outer side. This sheath is completed behind 
 by the ligament which extends from the pisiform to the unciform bone, and in front by a 
 sort of annular ligament. The nerve is covered by a synovial membrane during its 
 passage through this sheath. 
 
 As soon as it leaves this sheath, the ulnar nerve divides into two terminal branches, 
 the one superficial, and the other deep. 
 
 The superficial terminal branch, or trunk of the palmar collateral nerves of the fingers, im- 
 mediately gives off a branch which passes beneath the flexor brevis digiti minimi, pene- 
 trates the deep surface of that muscle, and immediately divides into two other branches, 
 an internal and an external. The internal is the smaller branch ; it crosses over the 
 muscles of the ball of the little finger, beneath the palmaris brevis, when it exists, gains 
 the inner side of the anterior surface of the little finger, and forms its internal palmar col- 
 lateral nerve, j The external is larger; it sends a communicating twig to the median 
 nerve, and bifurcates to form the external palmar collateral nerve of the little finger, and the 
 internal palmar collateral nerve of the ring finger. 
 
 The deep terminal or muscular branch is somewhat larger than the superficial branch 
 Immediately after its origin, it is reflected outward below the unciform bone, perforates 
 the flexor brevis digiti minimi, and passes deeply into the palm of the hand, so that it 
 cannot be exposed without dividing all the tendons of the palmar region. 
 
 This branch describes a transverse curve or arch with the concavity directed upward, 
 in front of the metacarpal bones, corresponding to and situated within the curve de- 
 scribed by the deep palmar arterial arch, which crosses it at an acute angle. 
 
 No branch arises from the concavity of this nerve, but from its convexity a great mmi 
 her are given off, in the following order : 
 
 During the passage of the nerve between the pisiform and unciform bones, three branch- 
 es for the three muscles of the hypothenar eminence. 
 
 Two very remarkable descending filaments, which supply the palmar interossei of the 
 third and fourth spaces, and end in the third and fourth lumhricalcs. The first and sec- 
 ond lumbricales, and frequently the third also, are supplied by the median nerve. 
 
 Three perforating branches pass backward between the upper ends of the metacarpal 
 bones, give some branches to the palmar interossei, proceed along the cellular interval 
 between the palmar and dorsal interossei, supply the last-mentioned muscles, and termi- 
 nate by anastomosing with the dorsal collateral branches of the ulnar and radial nerves. 
 
 We may regard as terminal divisions of the deep branch, two branches, which are 
 given to the two portions of the adductor pollicis,t and a branch for the first dorsal inter- 
 osseous muscle, from which a filament is given off that enters the adductor poUicis near 
 its lower border. 
 
 Summary. — From what has been stated, it appears that the ulnar nerve gives off no 
 branch in the arm ; that in the forearm it supplies some articular branches to the elbow- 
 joint, certain muscular branches for the flexor carpi ulnaris, and the inner half of the 
 flexor profundus, and a cutaneous filament which anastomoses with the internal cu- 
 taneous nerve ; that it gives off to the hand a dorsal cutaneous branch, from which the 
 dorsal collateral nerves of the little and ring fingers, and the internal dorsal collateral of 
 the middle finger, proceed ; a palmar cutaneous division, which supplies the palmar collateral 
 nerves of the little finger, and the internal palmar collateral nerve of the ring finger ; and 
 a muscular division, which is distributed to the three muscles of the hypothenar emi- 
 nence, to aU the interossei, among which we may include the adductor poUicis,^ and to 
 the two internal lumbricales. 
 
 * [This latter branch often anastomoses with the dorsal cutaneous branch of the radial nerve.] 
 
 t I have observed that it supplies the palmaris brevis, when that muscle exists. 
 
 i The reader must here be reminded, that 1 have regarded all that portiou of the flexor brevis pollicis (of 
 authors) which is situated to the inner side of the tendon of the flexor longus pollicis, or, in other words, all 
 that portion which is attached to the internal sesamoid bone, as belonging to the adductor pollicis. (See 
 Myology, p. 190.) The distribution of the nerves favours this view ; for the flexor brevis is supplied by 
 the median nerve, while the two portions of the adductor receive their nerves from the ulnar. [This general 
 statement is not quite correct ; the outer portion of the adductor (the inner_head of the flexor brevis of au- 
 thors generally) also receives a small branch from the median nerve (see p. 787 ; also Swan and Ellis).] 
 
 *) It is perfectly rational to consider the adductor pollicis as the first palmar interosseous muscle, which, fw 
 ♦hp sake of increased power of adduction, is attached to the third metacarpal bone. 
 
MUSCULO-8PIRAL NERVE. r^Bfli^ 
 
 ..k. ■ ,..^ ^^% A .. Musculo-spiral JVerve. i>i-;'*'I. 
 
 The musculo-spiral or radial nerve, which is the largest of the terminal divisions of the 
 brachial plexus, is intended for the triceps extensor cubiti, for the muscles of the pos- 
 terior and external region of the forearm, and for the skin of the arm, the forearm, and 
 dorsal region of the hand. 
 
 It arises {f,Jig. 286) from all the five nerves of which the brachial plexus is composed, 
 by a trunk which is common to it and to the circumflex nerve, and it issues from the 
 plexus behind the ulnar nerve, to which it is closely applied. Immediately after its ori- 
 gin, it passes downward, backward, and outward (b, fig. 288), in front of the conjoined 
 tendons of the latissimus dorsi and teres major, to gain the groove of torsion or spiral 
 groove of the humerus, into which it enters, passing between the long head of the tri- 
 ceps and the bone, then between the external head and the bone ; it traverses the whole 
 extent of this groove, and is in relation with the profunda humeri artery and vein. 
 Leaving this groove, opposite the junction of the two upper thirds with the lower third 
 of the humerus, it lies on the external and anterior aspect of the arm, descends vertical- 
 ly between the supinator longus and brachialis anticus, and next between the brachialis 
 anticus and extensor carpi radialis longior, crosses the elbow-joint (at b), passing in front 
 of the outer condyle of the humerus and the upper extremity of the radius, and then di- 
 vides into two terminal branches. 
 
 Collateral Branches of the Musculo-spiral Nerve. 
 
 During its winding and spiral course along the arm, this nerve gives off a great num- 
 ber of collateral branches in the following order : 
 
 Branches given off by the Musculo-spiral Nerve before it enters the Spiral Groove. — The 
 first is the internal cutaneous branch (/', fig. 287) of the musculo-spiral, which is sub- 
 aponeurotic at its commencement, but perforates the fascia, becomes applied to the skin, 
 and divides into two filjiments, which pass obliquely backward, and may be traced as far 
 as the olecranon.* 
 
 There are several considerable branches to the long head of the triceps ; the highest of 
 which is recurrent, and may be traced as far as the scapular attachments of the muscle. 
 A very large descending branch may be traced to the olecranon. 
 
 There is a branch for the internal head of the triceps, one division of which is rather 
 large, and runs along the inner border of the humerus in front of the muscle, which it 
 does not enter until it approaches the elbow. 
 
 Branches given off by the Musculo-spiral after leaving the Spiral Groove. — These are the 
 external cutaneous branch of the musculo-spiral, a very large branch which perforates the 
 muscular fibres of the triceps and the brachial aponeurosis, then lies in immediate con- 
 tact with the skin of the external region of the arm, passes obliquely backward, and di- 
 vides into a great number of filaments, which supply the skin of the posterior region of 
 the forearm, and may be traced down to the carpus. 
 
 The branch for the external head of the triceps and for the anconeus, which is remarkable 
 for its length, descends vertically between the external and long heads of the triceps, 
 supplies the former of these, enters the anconeus, and may be traced as far as the lower 
 part of that muscle. 
 
 All these branches are remarkable for being given off at nearly the same height ; that 
 is to say, near the shoulder-joint, and for accompanying the trunk of the musculo-spiral 
 nerve. 
 
 Branches given off by the Musculo-spiral Nerve in the Forearm. — These are the branches 
 for the supinator longus, and those for the extensor carpi radialis longior, which enter the 
 inner surface of the upper part of those muscles. 
 
 Terminal Branches of the Musculo-spiral Nerve. 
 
 Reduced to one half, or less, of its original size, by the successive emission of the pre- 
 ceding branches, the musculo-spiral or radial nerve divides in front of the elbow (b, fig. 
 388) into two unequal branches, the one deep or muscular, the other superficial or digital. 
 
 The deep or muscular division of the musculo-spiral nerve, or the posterior interosseous, 
 is larger than the superficial division ; it immediately gives off a branch which passes 
 vertically in front of the extensor carpi radialis brevier, and soon dips into that muscle ; 
 the nerve then becomes flattened, perforates the supinator brevis, and pursues a very 
 oblique and spiral course around the radius and within that muscle, to which it gives 
 branches {branches for the supinator brevis) : it then emerges from the posterior aspect of 
 this muscle, and immediately divides into a great number of diverging branches, some 
 of which are intended for the superficial, and the others for the deep layer of muscles on 
 the posterior region of the forearm. 
 
 The branches given to the superficial layer are, those for the extensor communis digt- 
 torum, which are very numerous and diverging, the superior being also recurrent; the 
 branch for the extensor proprius digiti minimi ; and the branch for the extensor carpi lU- 
 * [Anastomosing with the accessory of the internal cutaneous.) 
 
792 
 
 NEUROLOGY. 
 
 naris : all these branches arise by a common trunk, and enter the deep surface of the 
 muscles. 
 
 The branches for the deep layer also arise by a common trunk (i, Jig. 289), whicli may be 
 Fig. 289. regarded as the continuation of the muscular division of the mus- 
 
 culo-spiral, considerably diminished in size. This common trunk 
 passes vertically downward between the superficial and deep lay- 
 ers of muscles, gives off a branch, which enters the superficial as- 
 pect of the extensor longus ■pollicis, then passes between the adduc- 
 tor longus and extensor brevis pollicis on the one hand, and the 
 extensor longus pollicis on the other, runs in contact with the inter- 
 im/, osseous ligament, and gives off a first branch to the extensor lon- 
 gus pollicis, a second which enters the deep surface of the same 
 muscle, and a small branch which enters the outer border of the 
 entensor proprius indicis. 
 
 Reduced at length to a very small branch, the muscular division 
 of the musculo-spiral nerve enters the groove (at s) for the tendons 
 of the extensor communis digitorum, lying beneath them, in con- 
 tact with the periosteum ; it runs over the carpus, and expands into 
 a number of articular fdaments, which enter the radio-carpal, carpal, 
 and carpo-metacarpal articulations ; in this latter portion of its 
 course, the nerve is of a grayish colour, swollen, and, as it were, 
 knotted ; a condition which is observed in all articular nerves. 
 
 The superficial, cutaneous, or digital division of the musculo-spiral 
 nerve, or the radial nerve properly so called, forms the external dor 
 sal nerve of the hand, and is about half the size of the muscular di- 
 vision. It passes vertically downward, between the supinator lon- 
 gus and the extensor carpi radialis longior, along the outer side of 
 the radial artery : having reached the middle of the forearm, it es- 
 capes from beneath the tendon of the supinator longus, and runs 
 along the outer border of that tendon. 
 Situated at first beneath the fascia, it soon perforates it, becomes sub-cutaneous, runs 
 vertically downward, and, about an inch and a half above the styloid process of the radius, 
 divides into an external and an internal branch. 
 
 The external branch (o, figs. 288, 289), which is the smaller, runs along the outer side 
 of the styloid process of the radius, and then along the outer border of the carpus,* of 
 the first metacarpal bone, and of the first and second phalanges of the thumb, and termi- 
 nates in the skin beneath the nail ; it is the external dorsal collateral branch of the thumb. 
 The internal branch (e, fig. 289), which is much larger, passes obliquely behind the ra- 
 dius, crosses the tendons of the adductor longus and extensor brevis pollicis, and divides 
 into three secondary branches, namely, counting from without inward, the internal dor- 
 sal collateral nerve of the thumb, and the external and internal dorsal collateral nerves of thf 
 index finger, t 
 
 Summary. — The musculo-spiral nerve gives off, in the arm., two cutaneous branches, 
 one internal, the other external, the latter of which is much the larger, and may be tra- 
 ced as far as the carpus ; and also muscular branches to the three portions of the triceps 
 and to the anconeus : to the forearm, it supplies muscular branches to all the muscles of 
 the deep and superficial layers of the posterior and external regions ; and to the hand, 
 certain cutaneous branches, namely, the dorsal collateral nerves of the thumb and index 
 finger. 
 
 General Summary of the Distribution of the Jferves of the Brachial Plexus. 
 
 The preceding description shows that the brachial plexus supplies the skin, the mus- 
 cles, and the articulations of the upper extremity, including the shoulder. We shall 
 briefly recapitulate, first the muscular and then the cutaneous branches. 
 
 The Muscular Branches. — By its collateral branches, the brachial plexus supplies the 
 scaleni and all the muscles which move the shoulder, excepting the trapezius, which 
 receives its nerves from the brachial plexus and from the spinal accessory nerve of Wil- 
 lis ; by its terminal branches it supplies all the muscles of the arm, the forearm, and the 
 hand. 
 
 Each of the muscles which move the shoulder receive a special nerve ; thus, besides the 
 nervous filaments for the scaleni, there is the nerve for the sub-clavius ; the nerve for 
 the levator anguU scapulae ; the nerves for the rhomboideus ; the nerve for the serratua 
 magnus, which is better known as the external thoracic nerve ; the nerve for the latis- 
 simus dorsi, which is generally described as a branch of the sub-scapular ; and the nerves 
 for the pectoralis major and minor. 
 
 The muscles which move the arm upon the shoulder also receive their nerves from the 
 
 * [NVhere it sends an anastomotic filament to the palmar cutaneous branch of the median. J 
 t [It also supplies the external dorsal collateral of the middle finger, and often unites with tlie ulnar cuta- 
 oeius, to form the dorsal collaterals for the contiguous sides of the middle and ring fingers.] 
 
THE NERVES OF THE BRACHIAL PLEXUS. 793 
 
 brachial plexus ; sometimes there is a separate nerve for each muscle, sometimes the 
 same nerve supplies two muscles. The nerve for the deltoid, or the circumflex nerve, 
 also supplies the teres minor. The supra-spinatus and infra-spinatus receive their fila- 
 ments from the same branch, viz., the supra-scapulum nerve. The teres major receives 
 a branch from the sub-scapular nerve.* 
 
 Of the muscles which move the forearm upon the arm. Those of the anterior region, oi 
 the flexors, viz., the biceps, coraco-brachialis, and brachialis anticus, receive their fila- 
 ments from the musculo-cutaneous nerve ; the muscle of the posterior region, the tri- 
 ceps, is supplied entii ely by the musculo-spiral nerve. The ulnar nerve gives no branch 
 in the arm. 
 
 The muscles which move the radius upon the ulna, and those which move the hand and the 
 fingers, are thus supplied. The interosseous division of the musculo-spiral nerve sup- 
 plies the muscles of the posterior region of the forearm, viz., in the superficial layer, the 
 common extensor, the extensor proprius digiti minimi, and the extensor carpi ulnaris ; 
 in the deep layer, the supinator brevis, the adductor longus, extensor brevis, and extensor 
 longus pollicis, and the extensor proprius indicis. 
 
 The muscles of the exterior region of the forearm, namely, the two supinators, and the 
 two radial extensors of the carpus, also receive their branches from the musculo-spiral 
 nerve. 
 
 The muscles of the anterior region of the forearm receive their filaments from the median 
 nerve, excepting the flexor carpi ulnaris and the internal half of the flexor profundus, 
 which are supplied by the ulnar nerve. The flexor profundus, then, by a peculiarity 
 which not unfrequently occurs in regard to compound muscles, receives its nerves from 
 two different sources. 
 
 The intrinsic muscles of the hand are supplied in the following manner : Those of the 
 ball of the thumb by the median nerve ; those of the ball of the little finger by the ulnar 
 nerve ; the two external lumbricales by the median nerve ; the two internal lumbricales 
 by the ulnar nerve ; all the interossei, including the adductor pollicis, by the ulnar nerve. 
 
 The Cutaneous Branches A — The skin which covers the shoulder on the outer side re- 
 ceives its nerves from the cervical plexus. 
 
 The skin of the external surface of the arm receives its nerves from the cutaneoiis 
 branches of the circumflex nerve, and from the external cutaneous branch of the mus- 
 culo-spiral. The skin of the anterior and internal regions of the arm receives its nerves 
 from the internal cutaneous branch of the musculo-spiral, from the accessory nerve of 
 the internal cutaneous, which anastomoses with the second intercostal, from a small 
 branch of the internal cutaneous, and from the humeral branch of the third intercostal. 
 
 The skin of the forearm receives its filaments from the internal cutaneous, which 
 anastomoses with the cutaneous filaments of the musculo-spiral, ulnar, and musculo-cu- 
 taneous nerves. 
 
 The skin of the dorsal region of the hand and of the fingers receives its filaments from 
 the dorsal branches of the radial nerve, in the two external thirds of that region, and 
 from the dorsal branch of the ulnar nerve in the internal third. 
 
 The skin of the palmar region of the hand and fingers receives its filaments from the 
 median nerve in the two external thirds, and from the ulnar in the internal third, or, to 
 speak more precisely, the median nerve supplies the external and internal collateral 
 branches of the thumb, the index, and the middle fingers, and the external collateral 
 nerve of the ring finger ; the ulnar nerve supplies the external and internal collateral 
 nerves of the little finger, and the internal collateral branch of the ring finger. 
 
 Some of the terminal branches of the median nerve, and the terminal divisions of the 
 internal cutaneous and musculo-cutaneous, are lost in the skin of the upper part of the 
 palm of the hand. 
 
 The palmar collateral nerves of the fingers offer the following peculiarities : the 
 branches which they give to the skin are placed either opposite to each other, or alter- 
 nately ; each of these branches tenninates separately in a pencil of filaments ; the twigs 
 from the internal branches do not anastomose with those from the external ; lastly, the 
 terminal extremities of the external and internal collateral branches do not anastomose 
 with each other in the pulp of the finger, but expand separately, and are distributed to 
 the skin of the pulp and to the skin under the nail. 
 
 The branches which supply the palmar aspect of the fingers present a very remark- 
 able condition,t consisting in the presence of small, grayish, gangliform bodies, always 
 of a crescentic form. These bodies are very numerous ; they are sometimes separate, 
 
 * The teres minor and the infra-spinatus are, therefore, supplied by two different branches, which would 
 induce us to describe these muscles separately, did we not see that compound, and sometimes even simpla 
 muscles receivo-two or more distinct nerves.- 
 
 t A beautiful preparation of the cutaneous nerves of the upper extremity may be made by removing Ihs 
 skin, either by turning it inside out, in the same way as an eel is skinned, or by making a longitudinal incision 
 along the outer side of the limb. In both cases the fascia should be removed with the skin. In the first meth- 
 od, by which a very fine preparation may be made, the everted skin represents a kind of glove, the inner sui- 
 face of which is formed by tlie epidermis, and the outer by the deep surface of the skin 
 
 X This was pointed out in one of the last concours of tlie assistants (aides) of the Faculty, by M.M. AndjaJ, 
 ramus, and Lacroix, who had to dissect the cutaneous nerves of the hand. 
 
 5 H 
 
704 NEUROLOGY. 
 
 and sometimes arranged in groups ; they do not essentially belong to the nerves, but are 
 applied to them, and may be separated from them by slight force. They are, therefore, 
 not ganglia. 
 
 If we consider that these gangliform bodies occupy the palmar region only, and are 
 never found in the dorsal region, that they exist in the sole of the foot as well as in the 
 palm of the hand, that they have been found upon the nerves which surround the artic- 
 ulations, and, consequently, upon nerves which are subject to constant pressure, that I 
 have even found them upon an intercostal nerve which was reflected over the side of 
 the sternum, and, lastly, that they do not exist in the infant at birth, and are more numer- 
 ous in proportion as the palm of the hand is more callous we shall be warranted in con- 
 cluding that they are the result of external pressure. 
 
 THE ANTERIOR BRANCHES OF THE DORSAL NERVES, OR THE INTER- 
 COSTAL NERVES. 
 
 Dissection. — Enumeration. — Common Characters. — Characters proper to each. 
 
 Dissection. — Search carefully for the cutaneous branches, some of which are to be 
 found opposite the sides of the sternum, and others about the middle of the intercostal 
 spaces. Saw through the sternum in the median line, and open the abdomen through 
 the linea alba. Sacrifice one half of the thorax, or, rather, break the ribs through the 
 middle, so as to trace the nerves from within outward. 
 
 The anterior branches of the dorsal nerves, twelve in number, are intended for the parietes 
 of the thorax and abdomen.* 
 
 These branches offer at once a great uniformity, and a great simplicity in their distri- 
 bution. I shall first explain their common characters, and shall then notice the pecu- 
 liarities Dresented by each. 
 
 Common Characters. 
 
 The anterior branches of the dorsal nerves, or the intercostal nerves, separated from the 
 posterior branches by the superior costo-transverse ligament, appear like flattened cords, 
 which pass to the middle of the corresponding intercostal space (see^lf^. 268) ; there they 
 are situated between the pleura and the aponeurosis, which is continuous with the in- 
 ternal intercostal muscle. After proceeding for a certain distance, they pass between 
 the external and internal intercostal muscles, and approach the groove of the rib above, 
 but they are not lodged in it, for they always lie below the intercostal vessels. 
 
 At about the same situation in each space, that is to say, about half way between the 
 vertebral column and the sternum, the intercostal nerves divide into two branches, the 
 one intercostal, and the other perforating or cutaneous. 
 
 The intercostal branch is the continuation of the trunk of the nerve, and is distinguish- 
 ed from it only by its smaller size. It runs along the lower border of the rib above, and 
 then that of the corresponding costal cartilage ; it is sometimes situated on the internal 
 surface of the cartilage, and having reached the forepart of the intercostal space, it per- 
 forates this space from behind forward, runs along the sternum, is inclined somewhat 
 inward over that bone, and is then reflected outward, between the pectoralis major and 
 the skin, to which latter it is distributed. These small filaments may be called the an- 
 terior perforating filaments. During its course, the intercostal nerve and its continua- 
 tion give off a great number of nervous filaments. Not unfrequently the intercostal 
 nerve gives off, in the back part of the space, a small branch, which reaches the upper 
 border of the rib below. When this branch does not exist, its place is supplied by sev- 
 eral twigs which have a similar distribution, some of which even pass to the intercostal 
 space below, crossing obliquely over the internal surface of the rib. In like manner, we 
 sometimes find some small twigs proceeding from the upper side of the nerve over the 
 internal surface of the rib above, and reaching the next intercostal space. Lastly, from 
 the lower side of the intercostal nerve and its continuation a series of twigs are given 
 off, which divide into filaments that curve towards each other so as to form arches or 
 loops, from which the terminal filaments proceed. In no part of the body are there found 
 longer or more delicate nervous filaments ; some of them run through half the length of 
 an intercostal space without diminishing in size, and several evidently belong to the 
 periosteum. 
 
 The perforating or cutaneous branches are often larger than the intercostal branches ; 
 they pass very obliquely through the external intercostal muscles, and after running for 
 a certain distance between those muscles and the serratus magnus, each of them divides 
 into two smaller branches, the one anterior, and the other posterior or reflected : the an- 
 terior branches run horizontally forward, become sub-cutaneous by escaping between the 
 digitations of the serratus magnus in the eight superior intercostal spaces, and between 
 the digitations of the obliquus externus abdominis in the four lower spaces, and then, 
 
 * Haller only admits eleven dorsal nerves, because he considers, and not without reason, the twelfth as a 
 Inmbar nerve. " 
 
ANTERIOR BRANCHES OF THE DORSAL NERVES. 795 
 
 becoming applied to the skin, spread into a number of filaments, which almost always 
 anastomose with the adjacent filaments of the nerves above and below. 
 
 The posterior or reflected branches immediately perforate the serratus magnus and the 
 obliquus externus abdominis, are reflected upon themselves, pass backward between 
 the latissimus dorsi and the skin, and after running horizontally for a distance of one .or 
 two inches, are again reflected forward, and are then lost in the skin. 
 
 Proper Characters of each of the Anterior Branches of the Dorsal J^erves. 
 
 The First Dorsal Nerve. — This nerve belongs to the brachial plexus, into which it en- 
 ters immediately after its escape from the inter-vertebral foramen, crossing over the neck 
 of the first rib at an acute angle. P'rom its size, it resembles the lower cervical nerves, 
 and diflfers widely from the remaining dorsal nerves. It becomes intercostal only by 
 giving off a small intercostal twig at its exit from the inter- vertebral foramen. This in- 
 tercostal branch is applied to the under surface of the first rib, which it crosses obliquely 
 from behind forward, so that it does not reach the first intercostal space until opposite 
 the junction of the rib with its cartilage ; it gains the middle of this space near the ster- 
 num, at which point it passes forward through the space, like the other intercostal 
 nerves, and ramifies in the muscles and the skin. 
 
 The Second Dorsal Nene. — This nerve crosses obliquely over the second rib, on the 
 outer side of its neck, to reach the first intercostal space, and then recrosses the same 
 rib, about its middle, to gain the second intercostal space, where it divides into two 
 branches : the intercostal, which follows the lower border of the second rib, and presents 
 nothing remarkable ; and the -perforating or cutaneous branch, which requires a special 
 description. 
 
 The perforating or cutaneous branch, which is destined exclusively for the skin of the 
 arm, is much larger than the other branches of the same kind. It emerges from the 
 thorax at the middle of the second intercostal space, immediately below the second rib, 
 passes directly through that space, is reflected at right angles over an aponeurotic arch, 
 runs outward, and immediately subdivides into two branches of equal size, the one ex- 
 ternal and the other internal. 
 
 The external or intercosto-humeral branch (to the left of d, fig. 287) traverses the axilla, 
 receives an anastomotic twig from the accessory nerve (c) of the internal cutaneous of 
 the ann, reaches and crosses over the outer border of the latissimus dorsi, and divides 
 into two cutaneous filaments, one of which is distributed to the skin of the posterior re- 
 gion of the arm, while the other lies in contact with the skin of the internal region of the 
 arm, runs parallel to the accessory nerve of the internal cutaneous, and may be traced 
 as low down as the elbow. 
 
 The internal branch crosses the outer border of the latissimus dorsi, lower down than 
 the preceding branch, becomes applied to the skin, and divides into internal and posterior 
 filaments, which are lost in the skin of the arm. 
 
 The perforating branch, therefore, of the second dorsal nerve completes the system 
 of cutaneous nerves of the arm. 
 
 The third dorsal nerve is precisely similar to the others, excepting in its perforating, 
 cutaneous, or intercosto-humeral branch, which is distributed to the integuments both of 
 the thorax and arm. It is much smaller than the preceding ; it emerges (d,fig. 287) from 
 between the digitations of the serratus magnus, is reflected backward upon itself, gives 
 a small branch to the mamma, crosses the outer border of the latissimus dorsi, below the 
 perforating branch of the preceding nerve, and having reached the upper part of the 
 shoulder, is reflected upon itself, describing a curve with the concavity turned upward, 
 and terminates in the skin of the inner and upper part of the arm. 
 
 The fourth, fifth, sixth, and seventh dorsal nerves agree exactly with the general descrip- 
 tion. The intercostal muscles, the triangularis stemi, the serratus magnus, the obli- 
 quus externus abdominis, the upper part of the recti abdominis, and the integuments of 
 the thorax, are supplied with nerves from these branches, in the order and manner al- 
 ready pointed out. I would direct attention to the considerable number of filaments dis- 
 tributed to the skin of the mamma in the female. The perforating branches of the fourth 
 and fifth dorsal nerves each give a branch to the mamma, and a posterior branch, which 
 crosses the latissimus dorsi, and is distributed to the skin over the scapula ; the skin of 
 the mamma receives nerves from the third, fourth, and fifth dorsal nerves. 
 
 The eighth, ninth, tenth, and eleventh dorsal nerves belong to the intercostal spaces form- 
 ed by the false ribs : they leave those spaces at the point where the costal cartilages 
 change their direction to bend upward ; they perforate the costal attachments of the di- 
 aphragm, without giving that muscle any filaments, continue their oblique course in the 
 substance of the parietes of the abdomen, for which they are destined, and are distribu- 
 ted to these parts, in the same way as the nerves in the intercostal spaces, with some 
 slight modifications. Thus, the perforating branches perforate the external intercostals 
 and the obliquus externus abdominis in the same line as the perforating branches of the 
 preceding nerves ; the intercostal branches, properly so called, having thus become ab- 
 dormnal, run between the external and internal oblique muscles, just as, in the upper spa- 
 
fBi NEUROLOGY. 
 
 ces, they ran between the external and internal intercostals. Having reached the rec- 
 tus abdominis, they give off a cutanemis or perforating branch, and then enter the sheath 
 of that muscle, through certain openings at its outer border, and proceed between the 
 muscle and the posterior layer of the sheath : at the junction of the two external thirds 
 with the internal third of the rectus, these branches pass through it very obliquely to- 
 wards the middle line, and divide into muscular filaments, which are lost in the muscle, 
 and the lowest of wliich pass vertically downward, and cutaneous filaments, which per- 
 forate the anterior layer of the sheath of the rectus, on each side of the linea alba, but 
 not always at the same distance from it, and are reflected horizontally outward in the 
 sub-cutaneous cellular tissue lying immediately in contact with the skin. 
 
 The twelfth dorsal nerve {d, fig. 290) might, according to the opinion of Haller, be re- 
 garded as the first lumbar nerve. It is larger than the other dorsal nerves ; it emerges 
 from the vertebral canal between the last rib and the first lumbar vertebra, passes in 
 front of the costal attachments of the quadratus lumborum, runs along the lower border 
 of the twelfth rib, proceeds very obliquely downward, like that rib, perforates the apo- 
 neurosis of the transversalis muscle, and, like the preceding nerves, divides almost im- 
 mediately into two branches. The abdominal branch, which corresponds to the inter- 
 costal branch of the other nerves, passes horizontally forward between the transversalis 
 and obUquus internus, supplying those muscles, and almost always gives off, below, an 
 anastomotic branch to the abdominal or ilio-inguinal branch of the lumbar plexus, and 
 then penetrates the sheath of the rectus, where it is arranged like the preceding nerves. 
 
 The perforating or cutaneous branch is remarkable for being larger than the abdominal 
 branch, and for its distribution ; it perforates very obliquely, and at the same time gives 
 branches to the external and internal oblique muscles, becomes sub-cutaneous, passes 
 vertically downward, crosses at right angles over the crest of the ilium, and divides into 
 anterior, posterior, and middle branches, which are distributed to the skin of the gluteal 
 region. 
 
 Not unfrequently this gluteal cutaneous branch is given off by the first lumbar nerve, 
 and then the cutaneous branch of the twelfth dorsal nerve is arranged like those of the 
 preceding nerves, and ramifies in the skin between the last rib and the crest of the ili- 
 um. There is a mutual relationship between the twelfth dorsal and the first lumbar 
 nerves, so that they are often inversely developed ; they always communicate with each 
 other by a branch called the dorsi-lumbar, but the mode and place of communicati»n are 
 subject to many varieties : thus, it is sometimes effected by a winding branch which 
 runs along the outer border of the quadratus lumborum, at other times it takes place in 
 the substance of the abdominal muscles.* 
 
 Summary of the Dorsal or Intercostal JVerves, 
 
 These nerves are distributed to the parietes both of the thorax and the abdomen, which 
 in all respects 'may be regarded as constituting a single cavity, the thoracico-abdominal. 
 The muscular and cutaneous thoracic branches from the brachial plexus, some small 
 branches derived from the lumbar plexus, and the posterior spinal branches of the dorsal 
 nerves, complete the nervous system of the thoracic and abdominal parietes. 
 
 The dorsal nerves are divided into muscular nerves, for the muscles of the thoracico- 
 abdominal parietes, and for the muscles which lie upon them, and into cutaneous nerves. 
 To obtain a good idea of the latter, they should all be displayed in the same preparation. 
 Several rows of parallel cutaneous filaments will then be seen, in the following order, 
 proceeding from before backward. 
 
 The anterior perforating or cutaneous nerves, which are extremely small, emerge at the 
 sides of the sternum and of the linea alba, and are reflected forward. 
 
 The perforating or cutaneous nerves, which might be called middle, divide into orie set 
 of branches, which run parallel to each other forward, towards the sternum, and another 
 set, also parallel, which run backward, towards the vertebral column. 
 
 We have elsewhere stated that other posterior cutaneous branches are gren off from 
 the posterior branches of the dorsal nerves. They are parallel, and run outward, and 
 may be traced as far as on a level with the axilla. 
 
 THE ANTERIOR BRANCHES OF THE LUMBAR NERVES. 
 
 Enumeration. — The Lumbar Plexus — Collateral Branches, Abdominal and Inguinal. — Ter- 
 minal Branches — the Obturator Nerve — the Crural Nerve and its Branches, viz., the Mus- 
 culo- c^ttaneous — the Accessory of the Internal Saphenous — the Branch to the Sheath of the 
 Vessels — the Muscular Branches — the Internal Saphenous. 
 
 Dissection. — In order to see these nerves at their exit from the inter-vertebral forami- 
 na, and also to obtain a view of the lumbar plexus, it is necessary carefully to divide the 
 
 * In a subject which had a thirteenth or lumbar rib, there was a tTiirteenth dorsal nerve, of large size, 
 which crossed the supernumerary rib, and which corresponded in its distribution with both the twelfth dorsal 
 and the first lumbar nerves ; it only communicated with the first lumbar nerve by a very small filament ; it 
 gave off a deep perforating or cutaneous branch to the gluteal region, and also an ilio-scrolal branch. In thia 
 •abject there were only four lumbar nerves. 
 
THE LUMBAR PLEXUS. 
 
 797 
 
 psoas muscle, m which they are situated ; the branches which emerge from the plexus 
 must be dissected with the greatest care as they are passing under the femoral arch, 
 and then to their final distribution. 
 
 The anterior branches of the lumbar nerves (21 to 25, fig. 268) are five in number, and 
 are distinguished as the first, second, third, fourth, and fifth : they gradually increase in 
 size from the first to the fifth, and form a continuation of the series of anterior branches 
 of the dorsal nerves : after having given off one or two branches to the lumbar ganglia 
 (tt) of the sympathetic, and some branches to the psoas muscle, they end by anastomo- 
 sing so as to form the lumbar plexus (Z). 
 
 The anterior branch of the first lumbar nerve (1 I, fig- 290) is the smallest of all, and ia 
 almost equal in size to the anterior branch of the Fig-. 290. 
 
 twelfth dorsal nerve ; immediately after emerging 
 from the inter-vertebral foramen, it divides into 
 three unequal branches ; two of these (a and above 
 b) are external and oblique, and constitute the ab- 
 dmninal branches {ilio-scrotal nerves of some authors) ; 
 the third is internal, vertical, and often very small ; 
 it is the anastomotic branch which joins the second 
 nerve. 
 
 The anterior branch of the second lumbar nerve is at 
 least twice as large as the preceding ; it passes al- 
 most vertically downward, and gives off an anterior 
 branch, the internal inguinal (genito-crural of Bichat, 
 b), and an external branch, the external inguinal {in- 
 guino-cutaneous of Chaussier, c). It is scarcely di- 
 minished in size by giving oif these nerves, but be- 
 comes flattened, plexiform, and riband-shaped, fur- 
 nishes some large branches to the psoas, and anas- 
 tomoses with the third nerve. 
 
 The anterior branch of the third lumbar nerve is 
 twice as large as the preceding, passes obliquely 
 downward and outward, and is joined by the branch 
 from the second nerve, which greatly increases its 
 size. The large trunk thus formed, after a short course divides into two unequal branch- 
 es, which diverge at a very acute angle, and anastomose with two branches derived 
 from the fourth nerve, to constitute the crural (g) and the obturator (A) nerves. 
 
 The anterior branch of the fourth lumbar nerve is a little larger than the third ; it divides 
 after a short course into three branches : an external, which unites with the external 
 bifurcation of the third to form the crural nerve ; a middle, which unites with the internal 
 bifurcation of the same nerve to form the obturator nerve ; and an internal, vertical, an- 
 astomotic branch, which joins the fifth nerve. 
 
 The anterior branch of the fifth lumbar nerve (5 1) is somewhat larger than the fourth ; it 
 receives the internal branch of that nerve, and with it forms a large trunk, which enters 
 the sacral plexus, and was named by Bichat the lumbosacral nerve (i). 
 
 The Lumbar Plkxus. 
 
 The lumbar plexus (fig. 290) (lumbo-abdominal, Bichat) is a rather complicated inter- 
 lacement, formed by the anastomoses of the anterior branches of the lumbar nerves. It 
 is narrow above, where it consists of the sometimes slender communicating cord be- 
 tween the first and second lumbar nerves, and it becomes wider towards its lower part, 
 so as to have a triangular form ; it is situated upon the sides of the lumbar vertebrae, be- 
 tween the transverse processes and the fasciculi of the psoas muscle. 
 
 The branches which emanate from the lumbar plexus are divided into terminal branch- 
 es, namely, the crural (g), obturator (A), and lumbosacral nerves (i) ; and collateral branches, 
 improperly named musculo-cutaneous ; these are four in number ; they run between the 
 psoas and iliacus and the peritoneum, and reach the femoral arch. I shall divide these 
 collateral branches into two sets : an abdominal set, subdivided into the great (a) and 
 small (above b) ; and an inguinal set, subdivided into the internal (i) and external (c).* 
 
 Of these collateral branches, the abdominal only run in the sub-peritoneal adipose tis- 
 sue, the inguinal branches being covered by a layer of fascia, which keeps them in con- 
 tact with the psoas iliac muscle. 
 
 Collateral Branches of the Lumbar Plexus. 
 Jlbdominal Branches. 
 The abdominal branches of the lumbar plexus are intended for the parietes of the abdo- 
 
 * A change in the nomenclature of the collateral branches of the lumbar plexus appeared to me to be ne- 
 cessary. Bichat, who first distinguished them by special names, divides them into external or musculo-cuta- 
 neous branches, and an internal or genito-crural branch. Of the three external branches, Chaussier named 
 the external the ilio-sr'o'al. and the internal the inguino-culaneous ; the intermediate one, to which he gave 
 no particular name, - ■ ~ its old appellation of the midd/e JrancA. ■.- • 
 
798 NEUROLOGY. 
 
 men, and form a continuous series with the dorsal nerves, to which they are very anal- 
 ogous as regards their distribution.* 
 
 The great ahdominal nerve {a, fig. 270) is the most external, or, rather, the highest of 
 the branches which come from the lumbar plexus (it is the superior musculo-cutaneous 
 nerve of Bichat) ; the terms ilio-inguinal and ilio-scrotal, which are generally applied to 
 it, are derived from the fact of its giving a small cutaneous branch to the pubic region. + 
 
 It arises from the first lumbar nerve, of which it may be regarded as a continuation ; 
 it immediately perforates the psoas, becomes sub-peritoneal, runs in front of the quad- 
 r.itus lumborum obliquely downward and outward, through the sub-peritoneal adipose 
 tissue, parallel to the twelfth dorsal nerve, and thus reaches the crest of the ilium to 
 the outer side of the quadratus lumborum. It next passes obliquely through the aponeu- 
 rotic attachments of the transversalis, runs along the crest of the ilium between that 
 muscle and the obliquus internus, and divides into two branches, the abdominal branch, 
 properly so called, and the pubic branch. 
 
 The abdominal branch, properly so called, runs inward between the transversalis and 
 the internal oblique, parallel to the abdominal branch of the twelfth dorsal nerve, with 
 which it almost always anastomoses, and soon divides, like the lower intercostal nerves, 
 into two filaments, one of which perforates the rectus, while the other, after having en- 
 tered the sheath of that muscle, perforates it and ramifies upon the skin. 
 
 The pubic branch (a, fig. 292) continues in the original course of the nerve : opposite 
 the anterior superior spinous process of the ilium, and often much beyond that point, it 
 receives an anastomotic twig from the small abdominal nerve {¥), and sometimes even 
 the whole of that nerve, runs parallel to the femoral arch, at a variable distance above 
 it, meets with the spermatic cord in the male, and the round ligament in the female, 
 emerges from the anterior orifice of the inguinal canal {a, fig. 291), is reflected outward 
 upon the superior angle of that orifice, and then expands into internal or pubic filaments, 
 which are distributed to the skin of the pubes, and external filaments, which supply the 
 skin of the fold of the groin ; this pubic branch sometimes divides behind the femoral 
 arch into two filaments, which escape separately from the inguinal ring. 
 
 At the point where the great abdominal nerve reaches the crest of the ilium, it very 
 frequently divides into two branches, a gluteal cutaneous, which crosses obliquely over 
 the crest of the ilium, and an abdominal, properly so called, which is distributed in the 
 manner just described ; in this case, the great abdominal nerve has an analogous distri- 
 bution to that of the dorsal nerves. 
 
 The small abdominal or small musculo-cutaneous nerve (above b. Jig. 290), the second 
 branch derived from the lumbar plexus, counting from without inward (the middle muscu- 
 lo-cutaneous of Bichat), is merely an accessory of the great abdominal nerve, sometimes 
 arising from it, often applied to it, and always anastomosing with it. It crosses oblique- 
 ly over the anterior surface of the quadratus lumborum, and then over the iliacus, and is 
 sometimes directed obliquely outward towards the anterior superior spine of the ilium, 
 to join the pubic branch of the great abdominal nerve, with which it is blended ; it some- 
 times runs alone between the transversalis and internal oblique : having reached the 
 middle of the femoral arch, it anastomoses {b',fig. 291) by a single twig with the pubic 
 branch of the great abdominal nerve, runs along the femoral arch below and parallel to 
 that branch, and terminates in the same manner, that is to say, in the skin of the pubes 
 and groin. I have seen it give off a small branch to the lower part of the rectus ab- 
 dominis. The small abdominal nerve deserves the name of ilio-scrotal as much as the 
 great abdominal. If this denomination is to be preserved, it might be called the small 
 ilio-scrotal. 
 
 The Inguinal Branches. 
 
 The external inguinal, or external cutaneous nerve (c, fig. 290), the third branch of the 
 lumbar plexus, counting from without inward (inguino-cutaneoiis, Chauss. ; inferior mus- 
 culo-cutaneous, Bichat), is intended exclusively for the integuments of the external and 
 posterior regions of the thigh. It generally comes off from the second lumbar nerve : I 
 have seen it arise by a common trunk from the second and third lumbar nerves, and I 
 have also seen it come off from the outer side of the crural nerve. It arises by one and 
 often by two cords, which unite as they emerge from the psoas, or within the substance 
 of that muscle. In either case, the nerve passes obliquely through the back part of the 
 psoas, crosses the iliacus, being bound down by a layer of fascia, and then gains the an- 
 terior superior spinous process of the ilium, below which it emerges {cfig. 291) from the 
 abdomen, passing behind the femoral arch, and apparently increasing in size during its 
 passage. 
 
 Below the femoral arch the nerve is sub-aponeurotic, or, rather, is situated in a sheath 
 
 * The varieties ^¥hich they prpsent as to their number, origin, and divisions, render their description diffi- 
 cult ; I shall point out the most important varieties as we proceed. 
 
 t I have frequently found the great abdominal branch divided into two distinct branches, which anastomosed 
 upon the crest of the ilium, and then had a common distribution. I have seen the uppermost division lying 
 »o close to the twelfth dorsal nerve that it might have been taken for a branch of that nervo. 
 
THE INGUINAL BRANCHES, ETC. 799 
 
 formed by the deepest layers of the fascia lata, and divides into two cutaneous branches 
 (c c,fig. 292), a posterior or gluteal,* and an anterior or femoral. 
 
 The posterior or gluteal branch turns very obliquely outward, downward, and backward, 
 crosses the tensor vaginae femoris, and is distributed to the skin of the posterior region 
 of the thigh. It is sometimes derived from the internal inguinal nerve, and then emerges 
 from the abdomen on the outer side of the external inguinal nerve, crossing obliquely in 
 front of it. When the great abdominal nerve (ilio-scrotal of authors) gives off a cuta- 
 neous gluteal branch, there is only a trace of this posterior branch of the external ingui- 
 nal nerve. 
 
 The anterior or cutaneous branch divides into two others, which diverge at an acute 
 angle : one is external, the other hiternal ; the external branch gives off a series of fila- 
 ments, which pass backward and downward, forming loops with their concavities turned 
 upward, and is then lost towards the lower third of the thigh ; its place is then supplied 
 by the internal branch, which had at first descended vertically, but now turns outward 
 and backward, and is distributed over the outer and fore part of the knee. 
 
 These several divisions of the external inguinal nerve lie in contact with the femoral 
 fascia, and their ultimate filaments are applied to the skin. 
 
 The internal inguinal nerve (branche genito-crurale, Bichat ; rameau sous-pubien, 
 Chauss., b. Jig. 290) arises from the second lumbar nerve, passes directly forward 
 through the psoas, from which it emerges at the side of the bodies of the lumbar verte- 
 brae, runs vertically downward upon the anterior surface of the muscle covered by a very 
 thin layer of fascia, and having arrived within a greater or less distance from the femo- 
 ral arch, divides into two branches, an internal or scrotal, and an external ot femoral cuta- 
 neous branch (e). Not unfrequently this division takes place as the nerve emerges from 
 the psoas. Sometimes, indeed, the genito-crural nerve is double, but this arises merely 
 from its early subdivision. During its course, the internal inguinal nerve is crossed by 
 the ureter and covered by the spermatic vessels. + 
 
 The internal or scrotal branch (e, fig. 290) crosses over the front of the femoral artery, 
 gains the internal orifice of the inguinal canal, crosses the epigastric artery, and, before 
 entering the inguinal canal, gives off several filaments, which are reflected upward, and 
 dip into the substance of the internal oblique and transversalis ; the scrotal branch is 
 placed below the spermatic cord, from which it is perfectly distinct, runs with it through 
 the whole length of the inguinal canal {b,fig. 291), rests upon the reflected portion of the 
 femoral arch or Gimbernat's ligament, and emerges from the external orifice of the in- 
 guinal canal, opposite the lower end of the external pillar : at this point it is reflected, 
 passes vertically downward behind the cord, and ramifies in the skin of the scrotum of 
 the male, and of the labia majora in the female. 
 
 The femoral cutaneous branch gains the crural ring ; but before entering the ring, it 
 gives off a great number of very delicate filaments, which are reflected upward behind 
 the arch, to be distributed to the lower part of the psoas-iliac and transverse muscles : 
 it then passes through the crural ring, in contact with its outer angle, and crosses the 
 circumflex ilii artery at its origin, just as we have shown that the scrotal nerve crosses 
 the epigastric artery ; after leaving the crural ring (e, figs. 291, 292), it lies beneath the 
 fascia, but soon becomes sub-cutaneous, anastomoses with a cutaneous branch of the 
 crural nerve, and may be traced beyond the middle of the thigh, t 
 
 I have already stated, in describing the external inguinal nerve, that the posterior or 
 gluteal cutaneous branch of the external inguinal nerve is often given off by the internal 
 inguinal nerve. In that case, this branch runs outward, crosses the external nerve at a 
 very acute angle under the femoral arch, and escapes from below the arch on the outer 
 side of that nerve to turn round the tensor vaginae femoris. Not unfrequently the fila- 
 ments for the lower part of the internal oblique and transverse muscles arise by one or 
 more distinct branches. 
 
 , The Terminal Branches of the Lumbar Plexus. 
 
 These are three in number, viz., the obturator nerve, the crural nerve, and the great 
 communicating branch between the lumbar and sacral plexus, called the lumbosacral 
 trunk or nerve, which I regard as a dependance of the sacral plexus. 
 
 The Obturator JVerve. 
 The obturator nerve (A, fig. 290), which is distributed exclusively to the external obtu- 
 
 * Not unfrequently the external inguinal nerve gives off a third and very small internal branch, which lies 
 immediately in contact with the skin of the anterior region of the thigh, and may be traced as far as the lower 
 third of that region. This branch always anastomoses with a cutaneous branch of the crural nerve. 
 
 t Sometimes a small filament comes off from the genito-crural nerve while it is still within the substance 
 of the psoas, descends vertically on the inner side of this nerve, gives off a filament which is lost upon the ex- 
 ternal iliac artery, and then again becomes united with the nerve from which it had been given off. 
 
 t In order to assist the memory, by connecting these nerves with important parts, I am in the habit of call- 
 ing the femoral cutaneous branch of the internal inguinal nerve the branch of the crural ring, and the scrotal 
 branch, the branch of the inguinal canal. The scrotal branch may be cut, in relieving the stricture in inguinal 
 hernia, by the division of Gimbernat's ligament ; and the femoral cutaneous branch may be wounded when the 
 external angle of the crural ring is divided for the relief of femoral hernia. 
 
800 
 
 NEUROLOGY. 
 
 rator muscle, to the three adductors of the thigh, and to the gracihs, is the smallest of 
 
 Fig. 291. 
 
 I'^'N- 
 
 \ m 
 
 the terminal branches of the lumbar plexus ; it arises from the 
 third and fourth lumbar nerves by two equal branches, which 
 unite at an acute angle ; it perforates the psoas, passes under the 
 angle of bifurcation of the common iliac artery and vein, runs 
 along the inner surface of the psoas, crosses very obliquely over 
 the sides of the brim of the pelvis, and is then placed below 
 the external iliac vessels, with which it forms an acute angle, 
 and above the obturator artery : throughout the whole of this 
 course, it is enveloped in the sub-peritoneal cellular tissue of that 
 region, and, thus flattened and enlarged, reaches the internal ori- 
 fice of the obturator or sub-pubic canal, on emerging from which 
 it expands into diverging branches (A, fig. 291) for the adductors 
 and the gracilis muscle of the thigh. 
 
 Collateral Branch. — The obturator nerve gives off no branch in 
 the pelvis : during its passage through the obturator or sub-pubic 
 canal, it gives two filaments to the obturator cxternus ; one of these 
 penetrates the upper border of the muscle, and the other enters 
 at its anterior surface.* The obturator intemus receives no fila- 
 ment from the obturator nerve. 
 
 Terminal Branches. — These are four in number ;t three of them, 
 constituting a superficial set, pass under the pectineus, and are dis- 
 tributed as follows : the internal to the gracilis, the external to the 
 adductor longus, and the middle to the adductor brevis ; the fourth, 
 which is more deeply seated, belongs to the adductor magnus. 
 
 The branch for the gracilis expands, as it enters the muscle, into 
 several filaments, the largest of which (r,fig. 291) runs for some 
 distance upon the internal surface of the muscle before termi- 
 nating in it. 
 
 The branch for the adductor longus enters the upper border and 
 deep surface of the muscle : a rather large division (q) of this 
 branch, taking a different course, passes sometimes in front of 
 and sometimes behind the muscle, which is crossed by the nerve 
 in the first case, and perforated by it in the second ; the nerve 
 then divides into several filaments, some of which anastomose 
 with the accessory branch (at m) of the internal saphenous nerve, 
 while another anastomoses with the saphenous nerve itself, and 
 a third terminates in the synovial membrane of the knee-joint : 
 this is an articular nerve ; it may unite with the articular branch 
 of the nerve for the vastus internus. The anastomotic division 
 of the branch for the adductor longus is sometimes as large as the 
 musculfu: branch itself t 
 
 The branch for the adductor brevis crosses the upper border of 
 that muscle, expands upon it, but does not enter it until it reaches 
 the middle ; there is almost always an anastomotic twig, which 
 joins the internal saphenous branch of the crural nerve.<J 
 
 The fourth branch, or branch for the adductor magnus, is the deep' 
 est ; it passes between the adductor brevis and magnus, and ram- 
 ifies in the last-mentioned muscle. II 
 
 * [It also gives off, in this situation, articular filaments to the hip-joint ; these 
 are small or absent when the articular branches of the accessory to the obturator 
 are large.] ... . 
 
 t [Before dividing into its terminal branches, the obturator is joined by its ac- 
 cessory nerve (see notes, infra) ; it supplies a separate branch to the pectineus 
 ■when that from the accessory nei-ve is wanting.] 
 
 t See note, tn/rd. ,. l_, 
 
 ^ In a great number of subjects I have found a small nervous cord, which sometimes came oit from the third 
 lumbar nerve, sometimes from the obturator itself, and which may be called the accessory of the obturator 
 nerve, or the nerve of the coxo-femoral articulation ; it perforates the psoas to reach its inner surface, runs par- 
 allel to and above the obturator nerve, gains the pul)es, which it crosses on the inner side of the ilio-pectineal 
 eminence, with which it is in contact, dips beneath the pectineus, and anastomoses with the internal saphenous 
 nerve, passing into the angle of bifurcation of the femoral artery, where it gives off the profunda. Opposite 
 the pubes it gives off several branches, which perforate the fibrous capsule of the coxo-femoral articulation, 
 and are distributed to the synovial membranes. [This small accessory nerve was first described by Schmidt. 
 As it passes under the pectineus it partially supplies that muscle ; its anastomotic branch is described as uni- 
 ting with the obturator nerve beneath the pectineus, and not with the internal saphenous (see also notes p. 
 infra, et 803). The articular branch was believed by Schmidt to end in the fat near the acetabulum, w heii tne 
 accessory nerve is small, the articular filaments and the branch to the pectineus are replaced by others from 
 the trunk of the obturator itself In the pelvis the nerve has been seen to give filaments to the levator am.— 
 (Schmidt. I)e Ncrvis Lumbalibus eorumque Plexu, 1794 ; Dr. Alex. Thomson, Lond. Med. and Surg. Journal, 
 tios. 95, iXi : 'E]V\s, Demonstrations of Anatomt/).'i 
 
 II [In the dissections of Schmidt, Thomson, and Ellis, the branches of the obturator nerve were found to 
 have a much more extensive distribution than that described in the text. According to their observations, 
 »ne of the superficial branches, which is named the long cutaneous nerve (q,fig. 291), and which corresponds 
 
THE CRUKAL NERVE. 8QJ 
 
 ^ 
 
 ^^;. • . yv.i. .„>r,i- The Crural J^erve. . ^♦.rr**^;r:;. ' - 
 
 The crural nerve {g,]ig. 290) is the external terminal hraiu^'.i ol' the lumbar plexus; 
 the third and fourth lumbar nerves arc almost entirely devoted to the formation of thja 
 large branch, which supplies all the muscles of the anterior region of the thigh, and the 
 integuments of the anterior regions of the thigh, leg, and foot. 
 
 After emerging from the psoas, the crural nerve is lodged in the groove betw^een the 
 psoas and iliacus ; it escapes from the pelvis with this muscle, in the sheath of which 
 it is contained : having arrived below the femoral arch (^, jig. 291), it turns slightly out- 
 ward, becomes flattened and widened, and immediately divides into a great number of 
 diverging branches. The nerve sometimes bifurcates, and then gives off these different 
 branches. 
 
 Relations. — In the iliac fossa, the crural nerve is covered by the iliac fascia, and is 
 separated by the psoas from the external iliac artery and vein. Opposite the femoral 
 arch it always occupies the groove between the psoas and iliacus, and is situated on the 
 outer side of the femoral artery, being separated from the vessel by the psoas, which is 
 very narrow at that point. It is of importance to remark, that the crural nerve is not 
 contained in the sheath of the femoral vessels, but is separated from them by the iliac 
 fascia (see ^^. 136). 
 
 Collateral Branches. — ^In the pelvis, the crural nerve gives off from its outer side a 
 great number of small branches {iliac branches), which enter separately into the iliacus 
 muscle, after having run for some distance obliquely downward and outward upon the 
 surface of that muscle. Only one branch enters the psoas. One of the branches for the 
 iliacus is very long, and descends vertically in front of that muscle, into which it enters, 
 after having turned round its outer border. I have already said that the external ingui- 
 nal nerve {ingiiino-cutaneous of authors) not unfrequently arises from the crural nerve. 
 
 Of the terminal branches of the crural nerve there are two which arise in front of the 
 others : these are, the musculo-cutaneous nerve, and the small nerve for the sheath of the 
 femoral vessels.* The Other branches are, proceeding from without inward, the branch 
 for the rectus, the branches for the vastus externus, the branches for the vastus internus, and 
 the cutaneous branch, called the internal saphenous nerve. 
 
 The Musculo-cutaneous Crural Nerve. 
 
 This nerve passes obliquely downward and outward between the sartorius and the 
 psoas and iliacus, and immediately expands into muscular branches, distributed exclu- 
 sively to the sartorius, and cutaneous branches. 
 
 The muscular branches may be divided into the short, which enter the upper part of the 
 sartorius, and the long, which run for some distance upon the deep surface of that mus- 
 cle, before passing into it. 
 
 The cutaneous branches are three in number ; two of them perforate the sartorius at 
 different points, and may be called •perforating branches. I shall call the third the acces- 
 sory branch of the internal saphenous nerve. 
 
 The superior perforating cutaneous or middle cutaneous nerve {f,fig. 291) passes, very 
 obliquely, through the upper part of the sartorius, and often, as it emerges from that 
 muscle, anastomoses with a branch from the internal inguinal (genito-crural) nerve ; it 
 then passes vertically downward, parallel to and on the inner side of the external ingui- 
 nal (external cutaneous) nerve ; it Hes in contact with the femoral fascia (/, Jig. 292), 
 or, rather, is contained in a proper fibrous sheath. During its course, the superior per- 
 forating cutaneous nerve gives off internal and external cutaneous filaments, and bifur- 
 cates, opposite the middle of the thigh, into two branches of equal size, which run par- 
 allel to each other, gradually diminishing in size, and may be traced down to the skin 
 over the patella. 
 
 io the anastomotic division of the branch for the adductor longus, gives off cutaneous branches (q,fig. 292), 
 which perforate the fascia to the inner side of the sartorius muscle, and supply the skin on the inner part of 
 the thigh ; it also gives anastomotic branches to the plexus (m, Jig. 291 ) formed in the middle of the thigh, and 
 sometimes an articular filament to the knee {these anastomotic and articular branches are described in the 
 text, p. 800) ; it then ends in a descending cutaneous branch, which perforates the fascia near the knee (r,fig. 
 292), communicates with the intern.al cutaneous and internal saphenous nerves, and is distributed to the skin 
 on the inner and back part of the two upper thirds of the leg. The deep branch of the obturator gives off 
 within the upper part of the adductor magnus an articular filament destined for the knee-joint ; this filament 
 descends in the substance of the adductor near the linea aspera, and enters the popliteal space, either by per- 
 forating the tendinous insertion of the muscle about its lower third, or by coming forward on the front of that 
 insertion, and then passing backward through the opening for the femoral artery : having reached the popli 
 teal space, it surrounds the artery with small filaments, and enters the back part of the knee-joint. 
 
 The cutaneous branches just stated to be given off by the superficial part of the obturator to the thigh and 
 leg, and the articular filament given by the deep branch of the obturator to the knee-joint, correspond, in their 
 dittnbulion, with the three collateral branches described by M. Cruveilhier {p. 803) as arising from the in- 
 ternal saphenous nerve after it has received a remarkable branch of origin from the obturator nerve, opposite to 
 the commencement of the profunda artery : these collateral branches of the internal saphenous were never 
 met with in Mr. Ellis's dissections. In some cases, then, it seems that part of the obturator joins the internal 
 saphenous, which afterward gives off cutaneous branches to the thigh and leg, and an articular filament to the 
 knee ; in other c:»ses, again, the obturator does not join the internal saphenous, the above-mentioned branches 
 arise directly from the obturator, and the internal saphenous gives no collateral branches.] 
 
 ' LThe crural nerve also gives some small branches (s,_^^. 292), which pass inward behind the femoral 
 vessels, enter the pectineus muscle, and sometimes the psoas also.1 
 
 51 
 
802 NEUROLOGY. 
 
 Tlie inferior perforating cutaneous or internal cutaneous nerve {I, fig. 291) run along 
 the inner border of the sartorius, enclosed in its sheath, passes obliquely through the 
 muscle at the middle of the thigh, but perforates the femoral fascia much lower down {I, 
 Jig. 292) ; it descends vertically, in contact with that fiiscia, and having arrived opposite 
 the internal condyle of the femur, is reflected forward upon itself, describing a loop with 
 the concavity turned upward ; it thus gains the patella, runs between the skin and the 
 sub-cutaneous bursa, and expands into a number of diverging filaments, which anasto- 
 mose with the reflected branch (/ 1) of the internal saphenous nerve on the inner side of 
 the patella. A small filament often remains in the sheath of the sartorius, anastomoses 
 upon that muscle with a branch from the accessory of the internal saphenous nerve, per- 
 forates the sheath of the sartorius opposite the knee, and anastomoses, on the inner side 
 of the joint, with the reflected branch of the internal saphenous. 
 
 The accessory cutaneous branch of the internal saphenous nerve arises from the mus:. Ulo- 
 cutaneous nerve on the inner side of the perforating branches, descends vertically, and 
 divides into two branches. The smaller of these is superficial (n, fig. 291) ; it enters the 
 sheath of the sartorius, runs along the inner border of the muscle, escapes from the 
 sheath below the middle of the thigh, crosses the adductor and the gracilis, and is in 
 contact with the internal saphenous vein until it reaches the inner side of the knee, 
 where it anastomoses with the internal saphenous nerve. The other branch, the satel- 
 lite nerve of the femoral artery, crosses obliquely over the nerve for the vastus internu* 
 and the internal saphenous nerve, and is situated in front of the latter, runs along the 
 femoral artery, covering the lower fourth of that vessel, and crosses very obliquely over 
 it, then passes over the tendon of the adductor magnus, and, having reached the fibrous 
 ring through which the femoral artery passes, it expands into a great number of fila- 
 ments, of which one anastomoses with the preceding branch (w), another joins the obtu- 
 rator nerve (at m), and a third unites with the internal saphenous nerve ; a sort of plex- 
 us is thus formed which gives origin to several nerves that cross obliquely over the gra- 
 cilis, to be distributed to the skin upon the posterior region of the leg. 
 
 The Small Nerve for the Sheath of the Femoral Vessels. 
 
 This branch, which often comes oflT separately from the lumbar plexus, is situated, 
 like the musculo-cutaneous, in front of the other branches of the crural nerve ; it then 
 expands into a great number of very slender filaments, which surround the femoral ar- 
 tery and vein. Two of these filaments, of which one passes in front of and the other 
 behind the femoral artery, unite to form a small nerve {p,fig3. 291, 292), that escapes by 
 the opening (p) for the internal saphenous vein, and accompanies the vein for a great 
 part of its course. Not unfrequently, the filaments which have passed between the ar- 
 tery and vein perforate a lymphatic ganglion. Two other filaments are distributed to 
 the adductor brevis and adductor longus ; several of them turn round the deep femoral 
 artery and vein, to become sub-cutaneous, and anastomose with other accompanying 
 branches of the femoral vessels, and more particularly with the internal saphenous nerve. 
 
 This small branch presents many varieties. I have seen it arise separately from the 
 fourth lumbar nerve, and it then runs along the anterior surface of the crural nerve. 
 
 The Nerve for the Rectus Femoris. 
 The nerve for the rectus femoris arises on the inner side of the preceding, enters the 
 upper part of the deep surface of the muscle, and divides into a superior or short branch, 
 which passes horizontally outward in the substance of the muscle, and an inferior or long 
 branch, which lies in contact with its inner border, and enters the muscle at the middle 
 of the thigh. 
 
 The Nerve for the Vastus Externus. 
 The nerve for the vastus externus sometimes arises by a common trunk with the pre-' 
 ceding, passes obliquely downward and outward beneath the rectus, to which it gives &., 
 filament, and then divides into two branches : one of these immediately enters the upper 
 part of the vastus externus, and gives off, before penetrating it, a cutaneous branch, 
 which perforates the fascia lata and lies in contact with the skin of the external region 
 of the thigh : the other is longer, dips between the vastus externus and internus, and 
 enters the middle of the former muscle. This last branch almost always gives off a 
 sm8dl twig to the vastus internus. 
 
 The Nerves for the Vastus Internus.* 
 These are two in number ; the one is external, and descending vertically, enters that 
 portion of the vastus internus which corresponds to the anterior surface of the femur 
 (the crureus of authors), and may be traced as far as the lower part of the muscle : this 
 nerve furnishes several periosteal and articular filaments ; the other is internal, and much 
 larger ; it often arises by a common trunk with the internal saphenous nerve, runs ver- 
 tically downward in front of the vastus internus, parallel to and on the outer side of the 
 
 * It will be remembered that, according to my views, the portion of the triceps which is called the crurau 
 is not distinct from the vastus internus (see Mvojlooy). 
 
THE INTERNAL SAPHENOUS NERVE. 
 
 m 
 
 femoral artery, being in contact with that vessel above, but separated from it below, 
 where it enters the vastus intemus. Before penetrating it, it gives off a very remark- 
 able articular and periosteal branch, which runs along the surface of the muscle, to the 
 aponeurosis of which it is applied :* opposite to the knee-joint it is reflected forward, 
 perforates the thick fibrous layer which invests the inner side of the joint, and divides 
 into two filaments, of which one, the articular, is lost behind the ligamentum patellae in 
 the quantity of adipose tissue which is found there ; while the other, or the periosteal, 
 gains the anterior surface of the patella, and is lost in the periosteum. This last filament 
 is re-enforced upon the inner border of the patella by another which passes out from the 
 substance of the vastus intemus. 
 
 The Internal Saphenous Nerve. ^- 292. 
 
 The internal saptienous nerve {t t',fig. 291), the satellite nerve .; 
 
 of the femoral artery in the thigh, and of the internal saphenous 
 vein in the leg, is at first situated on the outer side of the ar- 
 tery, but soon passes in front of that vessel, and is contained in 
 the same fibrous sheath ; when the artery passes through the 
 tendon of the adductor magnus to enter the popliteal space, the 
 nerve continues its vertical course in front of that tendon, and 
 crossing it very obliquely from before backward, gains the back 
 of the internal condyle of the femur, situated in front of the ten- 
 don of the gracilis, and separated from the skin by the sartorius ; 
 it then divides into two terminal branches (m, t',figs. 291, 292). 
 This division often takes place £is the nerve is crossing the ten- 
 don of the adductor magnus. 
 
 Collateral Branches. — At its upper part, the internal saphenous 
 nerve receives from the obturator nerve a remarkable branch of 
 origin, which passes from behind forward in the angle formed by 
 the femoral artery and the profunda.! It then gives off from its 
 inner side, at the middle of the thigh, a cutaneous femoral branch, 
 which passes between the sartorius and the gracilis, runs back- 
 ward and downward, and is distributed to the skin of the poste- 
 rior and internal region of the thigh. Several filaments continue 
 their course to the inner and back part of the knee, anastomose 
 with some branches given off from the saphenous nerve in the 
 leg, and are distributed to the skin of the internal and posterior 
 region of the leg. 
 
 At the point where the femoral artery perforates the adduc- 
 tor magnus, the internal saphenous nerve gives off a second or 
 tibial cutaneous branch, which passes between the sartorius and 
 gracilis, turns round the inner border of the latter muscle, pass- 
 es vertically downward parallel to the saphenous nerve, and di- 
 vides into several filaments, some of which anastomose with 
 that nerve, while the others are distributed to the skin upon the 
 internal and posterior region of the leg. 
 
 In the sheath of the adductor magnus the saphenous nerve 
 gives off an articular filament, which passes vertically downward 
 in the substance of the internal inter-muscular septum, gains the 
 knee-joint, perforates the fibrous layer, and may be traced into 
 the synovial adipose tissue. t 
 
 Terminal Branches. — The anterior, reflected, or patellar branch 
 (u, figs. 291, 292) perforates the sartorius^ opposite to the back 
 of the internal condyle, is reflected forward and downward in 
 a flattened form upon the inner side of the knee-joint, parallel 
 to and above the tendon of the sartorius, and expands widely 
 into ascending filaments, which pass in front of the ligamentum 
 patellae, and turn round the lower and then the outer borders of 
 the patella ; into descending filaments, which cross obliquely over 
 the crest of the tibia, and ramify in the skin which covers the 
 external region of the leg ; and into middle filaments, which oc- 
 cupy the space between the two preceding sets ; they are all dis- 
 tributed to the skin, and several of them anastomose with the cu- 
 taneous filaments upon the external region of the patella. 
 
 * [In this situation it sometimes receives the articular filament of the anasto- 
 motic or long cutaneous branch of the obturator nerve.] 
 
 t [This junction of part of the obturator with the internal saphenous nerve was never seen in the dissec- 
 tions of Mr. Ellis, nor did the saphenous give any collateral branch in the thigh ; but branches correspond- 
 ing in their distriliution to the three collateral branches described in the text arose from the obturator itself 
 (see also note, p. 800.)] % See note, p. 800. 
 
 ^ The sartorius is, therefore, perforated in succession by three cutaneous branches, namely, two pprf.ii.i- 
 ting branches from the musculo-cutaneous nerve, and one from the internal st' •nous. 
 
804 NEUROLOGY. 
 
 The posterior or straight branch {t') is larger than the preceding, and continues in the 
 original course of the nerve ; it almost always receives an anastomotic branch from the 
 obturator nerve, passes in front of the tendon of the gracilis, then between the sartorius 
 and that tendon, which it crosses very obliquely, to meet the internal saphenous vein («), 
 whose direction it then follows : having arrived opposite the junction of the three upper 
 fourths with the lower fourth of the leg, it divides into two branches ; the one, posterior 
 and smaller, passes vertically downward in front of the internal malleolus, upon which 
 it ramifies, some of the filaments reaching as far as the skin upon the inner side of the 
 sole of the foot ; the other branch, which is anterior and larger, runs along the internal 
 saphenous vein, like it, is situated in front of the internal surface of the tibia, then in 
 front of the internal malleolus, and expands into articular branches, which enter the tib- 
 io-tarsal articulation, and into cutaneous filaments, which ramify in the skin upon the 
 inner side of the tarsus. 
 
 The following are the relations of the saphenous nerve with the internal saphenous 
 vein : the nerve is at first placed in front of the vein, then crosses obliquely under it to 
 get behind it, and, lastly, it again returns to its position in front of the vessel. 
 
 During its course along the leg, the posterior branch of the saphenous nerve gives off 
 some internal and some external branches : the internal branches are very small ; the up- 
 per ones anastomose with the tibial cutaneous branch of the trunk of the internal saphenous 
 nerve, and concur with it in supplying filaments to the skin of the back of the leg. The 
 external branches, three or four in number, are large, and, in this respect, diminish from 
 above downward ; their direction is obliquely downward and outward, in front of the tibia, 
 which they cross ; their course is a long one, and they are distributed extensively to dif- 
 ferent portions of the skin of the leg. All these divisions are parallel to each other, and 
 to the anterior reflected or patellar branch of the saphenous nerve. 
 
 THE ANTERIOR BRANCHES OF THE SACRAL NERVE. 
 
 Dissection. — Enumeration. — The Sacral Plexus. — Collateral Branches, viz., the Visceral 
 Nerves — the Muscular Nerves — the Inferior Hemorrhoidal — the Internal Pudic and its 
 Branches — the Superior Gluteal Nerve — the Inferior Gluteal, or Lesser Sciatic Nerve — 
 the Nerves for the Pyramidalis, Quadratus Femoris, and Gemelli. — Terminal Branch of 
 the Sacral Plexus, or the Great Sciatic Nerve. — The External Popliteal and its Branches 
 — the Peroneal Saphenous, Cutaneous, and Muscular Branches — the Musculo-cutaneous — 
 the Anterior Tibial. — The Internal Popliteal and its Branches — the Tibial or External 
 Saphenous — Muscular and Articular Branches — the Internal Plantar — the External Plan- 
 tar. — Summary of the Nerves of the Lower Extremity. — Comparison of the Nerves of the. 
 Upper with those of the Lower Extremity. 
 
 Dissection. — Make an antero-posterior section of the pelvis, as in dissecting the inter- 
 nal iliac artery. 
 
 The anterior branches of the sacral nerves (26 to 3\,fig. 268), which are six in number, 
 communicate with the sacral ganglia of the sympathetic, after they have emerged from 
 the sacral foramina, and present the following arrangement : 
 
 The first nerve (I, fig- 290), which is very large, passes obliquely downward and out- 
 ward, in front of the pyriformis, and is joined at a very acute angle by the lumbo-sacral 
 nerve (i), to assist in the formation of the sacral plexus. 
 
 The second nerve, which is as large as the preceding, passes much more obliquely 
 downward and outward, and immediately enters the sacral plexus. 
 
 The third nerve (3), which is scarcely one fourth as large as the second, passes more 
 horizontally outward to enter the sacral plexus. A considerable interval, in which is a 
 large part of the pyriformis, separates it from the second nerve. A filament stretched 
 in front of this muscle passes from the second to the third sacral nerve. 
 
 The fourth nerve (4), which is only one third the size of the third, is divided and dis- 
 tributed in the following manner : One of its divisions assists in forming the sacral 
 plexus ; it gives off several viscer^d branches, which enter the hypogastric plexus ; it 
 communicates with the fifth sacral nerve by another division ; it gives off one or two 
 branches to the coccygeus muscle ; and, lastly, it gives a cutaneous coccygeal branch, 
 which runs along the border of the sacrum, penetrates the great sacro-sciatic ligament, 
 crosses that ligament very obliquely, and turns round its lower edge, perforates the coc- 
 cygeal attachments of the glutseus maximus, passes very obliquely through the muscle, 
 gives branches to it, and then ends in the integuments. 
 
 The fifth and sixth nerves, which have no connexion with the sacral plexus, are ex- 
 tremely small ; the fifth is not more than half the size of the fourth ; the sixth is so very 
 slender a filament, that it has often escaped the notice of anatomists, and hence the in- 
 correct but prevalent opinion that there frequently exist only five sacral nerves. 
 
 The fifth nerve, at its exit from the anterior sacral foramen, divides into an ascending 
 branch, which comnaunicates with the fourth, and a descending branch, which passes di- 
 
COLLATERAL BRANCHES OF THE SACRAL PLEXUS. 805 
 
 recfty downward to anastomose with the sixth, of which it appears to form the ascend- 
 ing branch. 
 
 The sixlh nerve consists of a mere filament, which divides, while still contained within 
 the sacral foramen, into an ascending or anastomotic branch, which is merely the de- 
 scending branch of the fifth ; a descending or inferior coccygeal branch, which passes ver- 
 tically downward along the coccyx in the substance of the sacro-sciatic ligament, and is 
 distributed to the skin ; and certain external branches, which perforate the sacro-sciatic 
 ligament, and terminate in the glutaeus maximus. 
 
 The Sacral Plexus. 
 
 The sacral plexus {Jig. 290) is formed by the four upper sacral nerves (1 to 4) and the 
 lumbo-sacral nerve (i) from the lumbar plexus ; the three superior sacred nerves pass 
 entirely into this plexus ; the fourth nerve only sends one of its divisions to it. The 
 lumbo-sacral trunk or nerve, which emanates from the lumbar plexus, is formed by the 
 whole of the fifth lumbar nerve add0 to a branch from the fourth. This great nervous 
 trunk establishes a free connexion between the lumbar and sacral plexuses, which, in 
 fact, constitute only one plexus, which may be called the lumbo-sacral. I would here 
 recall to mind that there is a precisely similar arrangement with regard to the cervical 
 and brachial plexuses, to which the lumbar and sacral plexuses have an undoubted an- 
 alogy. 
 
 The sacral plexus is distinguished by its simplicity from most other plexuses, which 
 are always more or less complicated. It is formed by the convergence of five cords to- 
 wards the sciatic notch. As the lumbo-sacral cord is vertical, and the third and fourth 
 sacral nerves are horizontal, it follows that the form of the sacral plexus resembles a 
 triangle, the base of which measures the entire length of the sacrum, while its apex 
 corresponds to that portion of the sciatic notch which is situated above the spine of the 
 ischium. The great sciatic nerve («) is the continuation of this plexus, which, as Bichat 
 judiciously remarked, is merely the sciatic nerve itself flattened from before backward, 
 the intricacy of arrangement so evident in the plexus representing that which exists in 
 all nervous cords. 
 
 The following are the relations of the sacral plexus : It rests behind upon the pyri- 
 formis, and it corresponds in front to the internal iliac vessels, from which it is separa- 
 ted by a layer of fascia : these vessels also separate the plexus from the rectum and 
 peritoneum. 
 
 Of the collateral branches, some are anterior, namely, the visceral nerves, which enter 
 the hypogastric plexus ; the nerve for the levator ani ; the nerve for the obturator inter- 
 nus ; the internal pudic nerve : the other collateral branches are posterior, namely, the 
 superior gluteal nerve ; the inferior gluteal or lesser sciatic nerve ; the nerve for the 
 pyriformis ; the nerve for the geraelli ; and the nerve for the quadratus femoris. The 
 great sciatic nerve is the only terminal branch of the sacral plexus. 
 
 The Collateral Branches of the Sacral Plexus. 
 
 The Visceral Jferves. 
 
 Dissection. — After having made a section of the pelvis at one side of the symphysis, 
 turn the bladder and the rectum over to the same side ; carefully detach the peritoneum, 
 which is reflected from the pelvis upon these viscera ; lacerate the cellular tissue to 
 reach the branches given off" from the fourth nerve ; and then trace the rectal and vis- 
 ceral nerves, following the annexed description. It is advantageous to empty the large 
 veins of the pelvis, and to soak it in water for some time previously to dissecting these 
 nerves. 
 
 The visceral nerves do not, properly speaking, come from the sacral plexus, but rather 
 directly from the fourth and fifth sacral nerves ; they are three or four in number, and 
 pass upward upon the sides of the rectum and bladder in the male, and of the rectum, 
 vagina, and bladder in the female ; some of them are distributed directly to those organs, 
 but the greater number (y, fig. 302) enter the hypogastric plexus (m), which will be de- 
 scribed with the sympathetic system. 
 
 The JSTervesfor the Levator Ani. 
 
 Besides several rectal and vesical filaments which go to the levator ani, this muscle 
 receives two filaments directly from the fourth sacral nerve (4, fig. 290) : the larger of 
 these filaments enters the middle of the muscle ; the other, which is smaller, passes 
 upon the sides of the prostate in the male, and of the vagina in the female, and termi- 
 nates in the anterior portion of the muscle. 
 
 The Nerve for the Obturator Internus. 
 
 It arises from the anterior part of the sacral plexus, and more particularly from that 
 portion which belongs to the lumbo-sacral cord and the first sacral nerve ; it passes im- 
 mediately behind the spine of the ischium, is reflected forward through the small sciatic 
 
806 NEUROLOGY. 
 
 notch, and expands into three diverging branches, which are distributed within the mus- 
 cle. In order to expose this nerve, the lesser sacro-sciatic ligament may be divided. 
 
 The Inferior Hemorrhoidal J^erve. 
 
 This nerve, which is intended for the sphincter ani and the adjacent skin, arises (from 
 4, Jig. 290) on the inner side of the internal pudic nerve, of which it is sometimes a 
 branch, passes, like that nerve, behind the spine of the ischium, and then between the 
 two sacro-sciatic ligaments, reaches the front of that portion of the glutaeus maxiraus 
 which projects below the great sacro-sciatic ligament, communicates with the superfi- 
 cial nerve of the perineum, gains the side of the rectum, and opposite the upper border 
 of the sphincter expands into a great number of branches ; of these, some are anterior, 
 and often anastomose with one of the divisions of the superficial perineal nerve ; others 
 are median, and pass upon the sides of the sphincter ani as far as the skin, in which they 
 terminate ; lastly, others are posterior, and proceed to the back part of the sphincter. 
 The hemorrhoidal or anal nerve is sometimes di^pbuted exclusively to the skin round 
 the anus ; it may then be named the anal cutaneoits nerve. 
 
 The Internal Pudic JVerve. 
 
 Dissection. — It is convenient to commence the dissection of this nerve from within 
 outward, by dividing the lesser sacro-sciatic ligament, and separating the obturator fas- 
 cia from the obturator internus muscle. The superior branch of the nerve upon the dor- 
 siun of the penis may then be traced without taking it away. The perineal branches 
 must then be very carefully dissected, and the continuity of these branches with those 
 already dissected within the pelvis should be made out. 
 
 The internal pudic nerve (d. Jig: 293) arises from the lower border of the flattened 
 band formed by the nerves of the sacral plexus opposite to their junction ; it passes be- 
 hind the spine of the ischium, and then enters the ischio-rectal fossa through the lesser 
 sciatic notch, that is, between the two sacro sciatic ligaments, on the inner side of the 
 internal pudic artery, and divides into two branches (/, Jig. 290), the injcrior branch, or 
 'perineal nerve, and the superior or deep branch, or the dorsal nerve oj the penis. 
 
 The Perineal Nerve. 
 
 The inferior branch or perineal nerve corresponds to the trunk of the internal pudic ar- 
 tery, and to all its divisions, excepting the dorsal artery of the penis. It is the true con- 
 tinuation of the nerve, and accompanies the trunk of the internal pudic arterj", being sit- 
 uated below that vessel ; it runs forward and then upward between the obturator inter- 
 nus and the obturator fascia, describes a curve having its concavity directed upward, and 
 placed on the inner side of the tuberosity of the ischium, perforates the obturator fascia, 
 opposite to the junction of the tuberosity with the ascending ramus of the ischium, and 
 immediately divides into two branches : an inferior or anterior superficial perineal, which 
 corresponds to the superficial artery of the perineum ; and a superior, which corresponds 
 to the artery of the bulb, but which has a much more extensive distribution ; I shaU 
 call it the bulbo-urethral nerve. 
 
 The Collateral Branches of the Perineal Nerve. — During its course, the perineal nerve 
 gives off a branch which might l>e called the external perineal ( posterior superficial perin 
 eal) ; this branch perforates the great sacro-sciatic ligament, passes by the internal sur 
 face of the tuberosity of the ischium, turns inward and downward, and then beneath 
 the tuberosity, runs along the crus of the corpus cavernosum, and is lost in the dartos 
 and scrotum in the male, and in the substance of the labia majora in the female. I have 
 seen this nerve give a branch to the coccygeus, and two branches to the sphincter. 
 
 This external perineal branch, moreover, presents many varieties. In some cases it 
 terminates by anastomosing with the superficial branch of the perineum. In one case, 
 in which the external perineal branch was very small, it was re-enforced by a branch from 
 the inferior gluteal or lesser sciatic nerve, which crossed the outer side of the tuberosity 
 of the ischium, and united, in front of that tuberosity, with the external perineal branch. 
 
 The Terminal Branches of the Perineal Nerve. — The superjicial {anterior superjicial) pe- 
 rineal nerve follows the superficial artery of the perineum, passes, like it, obUquely in- 
 ward and forward, through the cellular interval between the ischio-cavernosus, and 
 bulbo-cavernosus, receives a rather large filament from the external perineal branch, and 
 almost always divides into several remarkably long filaments, which pass through the 
 dartos, some reaching the bottom of the scrotum, while others, running along the lower 
 surface of Uie penis, are distributed to the skin of that organ, and may be traced as far 
 as the prepuce. 
 
 The bulbo-urethral nerve, the second terminal branch of the perineal nerve, passes 
 above and sometimes through the fibres of the transversus perinei muscle, supplies some 
 small branches to the anterior part of the compressor urethrae and the posterior part of 
 the bulbo-cavernosus, furnishes a bulbar branch which dips into the substance of the 
 bulb, and then expands into very delicate filaments on the corpus spongiosum. 
 
DEEP BRANCH OF THE INTERNAL PUDIC, ETC. "gOV 
 
 The Deep Branch of the Internal Pudic, or the Dorsal Nerve of the Perns. 
 
 This is the highest of the terminal divisions of the internal pudic nerve, and corre- 
 sponds to the deep branch of the internal pudic artery. It is at first applied, together 
 with that vessel, against the internal surface of the tuberosity of the ischium, and pass- 
 ing upward between the levator ani and obturator internus, gains the arch of the pubes ; 
 it then runs forward among the sub-pubic veins through the several ligamentous struc- 
 tures below the arch, and reaches the dorsum of the penis, where it is situated at the 
 side of the suspensory ligament. Having now become the dorsal nerve of the penis, it 
 runs along that organ in the median line, like the dorsal artery, but superficially to that 
 vessel, and divides into an internal and an external branch. 
 
 The internal branch, or branch for the glans penis, continues in the original course of 
 the nerve upon one side of the median line, becomes more deeply seated as it runs for- 
 ward, but without entering the corpus cavernosum, and thus arrives at the corona glan- 
 dis ; at this point it expands and passes deeply between the base of the glans and the 
 corpus cavernosum, gives no filament to the latter, but is entirely distributed to the glans, 
 penetrating that part by extremely delicate filaments, which traverse the spongy tissue, 
 and may be traced, at least in a great measure, to the papillae on the surface of the glans. 
 
 The external or cutaneous branch, which is more superficial, comes off from the prece- 
 ding at a very acute angle, passes obliquely upon the sides of the penis, and expands 
 into a number of very long and slender filaments, some of which lie in contact with the 
 corpus cavernosum, and supply it with very slender filaments, "while others run into the 
 sub-cutaneous cellular tissue, and are distributed to the skin of the penis ; a considera- 
 ble number terminate in the prepuce. The external branch of the dorsal nerve of the 
 penis supplies the skin upon the three upper fourths of the circumference of the penis. 
 The perineal branches supply that of the lower fourth. I have not found any branch of 
 the internal pudic nerve corresponding to the artery of the corpus cavernosum. 
 
 In the female, when this nerve reaches the clitoris, it becomes very small ; it passes 
 under the arch of the pubes, between it and the cms of the clitoris ; it runs along that 
 crus, becomes curved like the clitoris itself, upon the side of which it expands into fila- 
 ments, and then ramifies in the substance of that organ ; several of the filaments run 
 forward to the skin of the anterior part of the labia majora. 
 
 The superficial perineal branch passes between the constrictor muscle and the bulb of 
 the vagina, and then terminates in these parts. 
 
 , The internal pudic nerve in the female does not appear to me to be half the size of the 
 internal pudic nerve of the male. In one case I found that it consisted only of the branch 
 for the clitoris, the superficial branch being supplied by the inferior gluteal nerve. 
 
 The Superior Gluteal JSTerve. 
 The superior gluteal nerve, which is intended for the glutaeus medius and minimus, and 
 the tensor vaginae femoris, arises from the back of the lumbo-sacral trunk, before its 
 junction with the first sacral nerve. I have seen it arising by two roots, of which one 
 came from the lumbo-sacral nerve and the other from the posterior surface of the plex- 
 us : it emerges from the pelvis (a, fig. 293) by the upper and fore part of the great sci- 
 atic notch, in front of the pyriformis, is reflected upon this notch to pass between the 
 glutaeus medius and minimus, and divides into two branches ; the one ascending, which en- 
 circles the origin of the glutaeus minimus, like the corresponding branch of the gluteal ar- 
 tery ; and the other descending, which passes obliquely downward and outward, between, 
 the glutaeus medius and minimus, to which it gives off numerous filaments, and thus, grad- 
 ually diminished in size, it embraces, as it were, the posterior surface of the glutaeus min- 
 imus, and having reached the external border of that muscle, it passes downward, and 
 enters the sheath of the tensor vaginae femoris, in which it terminates. Before entering 
 the sheath of the tensor vaginae it gives off a remarkable branch, which turns round the 
 anterior border of the glutaeus minimus, and ramifies in that muscle. 
 
 The JVervefor the Pyriformis. 
 This little nerve arises separately from the posterior surface of the sacral plexus, and 
 more particularly from the third sacral nerve ; it divides into two branches, which im- 
 mediately enter the anterior surface of the muscle. 
 
 The Inferior Gluteal JVerve. > 
 
 The inferior gluteal nerve (Bichat), or the lesser sciatic nerve {Boyer), is intended for the 
 glutaeus maximus, the integuments of the posterior region of the thigh, and for a part of 
 the skin of the leg. It arises from the back of the sacral plexus, sometimes by one 
 cord, sometimes by several very distinct cords. It emerges from the pelvis (near c,fig. 
 293), below the pyriformis, together with and on the inner side of the great sciatic nerve, 
 to which it may be regarded as an accessory ; it passes behind that nerve, and divides 
 into two sets of branches, viz., muscular and cutaneous. 
 
 The muscular branches (c) are numerous, although exclusively intended for the glutaeus 
 maximus ; they divide into ascending and external branches, which run along the ante- 
 
808 NEUROLOGY. 
 
 rior surface of the muscle, spread out upon it, and may be traced as far as its upper oor- 
 der, and descending and internal branches, which pass between the tuberosity of the is- 
 chium and the muscle, and then enter the latter. 
 
 The cutaneous branch (b) continues in the original course of the nerve, behind the great 
 sciatic, and in front of the glutajus maximus ; it crosses obliquely, downward and in- 
 ward, over the tuberosity of the ischium and the origins of the biceps and senii-tendi- 
 nosus muscles ; considerably reduced in size, from having given off several branches, it 
 assumes the name of lesser sciatic (/), runs vertically downward, becoming smaller and 
 smaller, and may be traced down to the posterior region of the leg. 
 
 The cutaneous branch, as it emerges from the glutaeus maximus, gives off a consid- 
 erable recurrent branch (e), which might be regarded as a terminal branch of the nerve. 
 This branch is reflected upward so as to describe a curve having its concavity turned 
 upward, and subdivides into two secondary branches, an internal and an external : the 
 external branch is the larger, and ramifies in the skin of the gluteal region ; the internal 
 or scrotal branch (pudendalis longus inferior, Sammering) is a very remarkable one ; it is 
 reflected forward upon the under surface of the tuberosity of the ischium, runs along at 
 some distance from the ascending ramus of the ischium and the descending ramus ot 
 the OS pubis, anastomoses with the superficial perineal nerve, reaches the scrotum above 
 the testis, and divides into two branches — an external, which passes on the outer side, 
 and an internal, which runs on the inner side of the testis ; having embraced this organ, 
 they are distributed to the skin of the anterior part of the scrotum and the lower part oi 
 the penis. In the female, this branch belongs to the labia majora. 
 
 All along the thigh, the cutaneous branch of the inferior gluteal nerve gives off some 
 very small external branches, and some larger internal branches, which are reflected 
 forward, describing curves having the concavity turned upward, and supply the skin of 
 the internal region of the thigh. 
 
 In the pophteal space, the cutaneous branch divides into two filaments, one sub-cuta- 
 neous, which may be traced, notwithstanding its extreme tenuity, as far as the middle of 
 the posterior region of the leg ; and the other sub-aponeurotic, which perforates the fas- 
 cia of the leg, runs along the external saphenous vein, and anostomoses with the exter- 
 nal saphenous nerve. 
 
 The Jferves for the Quadratus Femoris and the Gemelli. 
 
 The superior gemellus receives a special nerve from the anterior part of the sacral plexus. 
 The nerve for the inferior gemellus is a branch of the nerve for the quadratus femoris. 
 
 The nerve for the quadratus femoris is remarkable. It arises from the front of the sa- 
 cral plexus, or, rather, from the limit between this plexus and the great sciatic nerve, 
 passes vertically downward in front of the gemelli and obturator internus, by which it is 
 separated from the great sciatic nerve, and it is placed in contact with the os innomi- 
 natum, to the outer side of the tuberosity of the ischium. It gives off some external pe- 
 riosteal and osseous branches, which enter the foramina in the tuberosity of the ischium ; 
 some internal or articular branches, which perforate the fibrous capsule of the hip-joint ; 
 a branch for the inferior gemellus ; and then terminates in the quadratus femoris, which 
 it enters by its anterior surface. 
 
 The Terminal Branch of the Sacral Plexus, or the Great Sciatic Nerve. 
 
 The great sciatic nerve (grand femoro-poplite, Chauss.) is intended for the muscles of 
 the posterior region of the thigh, and for the muscles and integuments of the leg and 
 foot : it is the termination (s, fig. 290) of the sacral plexus, or, rather, it is the sacral 
 plexus itself condensed into a nervous cord. The fifth lumbar nerve, a branch of the 
 fourth lumbar, the three superior sacral nerves, and a branch from the fourth, form the 
 origins of this great nerve, which is the largest in the body. 
 
 It emerges from the pelvis, through the great sciatic notch, below the pyriformis im- 
 mediately above the spine of the ischium, passes vertically downward (s, fig. 293) be- 
 tween the tuberosity of the ischium and the great trochanter, both of which project so 
 as to separate it from the skin, or, more exactly, it runs along the outer side of the tu- 
 berosity of the ischium, in a very deep groove between that process and the margin of 
 the cotyloid cavity. At its exit from the pelvis, it is a flat, riband-shaped nerve, six 
 lines in breadth, but it soon becomes rounded, runs vertically downward along the back 
 of the thigh, sloping, however, a little outward ; having arrived about three or four fin- 
 gers' breadth above the knee-joint, it divides into two branches, which are called the 
 external popliteal sciatic or the peroneal nerve (i), and the internal popliteal sciatic or tibial 
 nerve (A). 
 
 The sciatic nerve sometimes divides at its exit from the pelvis, but it may do so at 
 any other point between that and the popliteal space. This premature division is of 
 no importance ; in fact, it always exists ; for when there is apparently only one trunk, 
 the two branches of the bifurcation are perfectly distinct through the whole length of 
 ihe thigh, and are merely in contact with each other.* 
 
 * When the great sciatic nerve divides within the pelvis, the upper division perforates the pyriformis, while 
 'He lower emerges from below that muscle. 
 
THE GREAT SCIATIC NERVE, ETC. 
 
 809 
 
 Relations. — Behind., the great sciatic nerve is covered by the Fig. 293. 
 
 glutaeus maximus, and then by the long head of the biceps and 
 the semi-tendinosus ; lower down it occupies the cellular inter- 
 val between these two last-named muscles, and when they sep- 
 arate from each other to form the borders of the popliteal space, 
 it becomes sub-aponeurotic. 
 
 In front, it corresponds to the gemelli and obturator internus, 
 by which it is separated from the os coxffi, to the quadratus femo- 
 ris and the adductor magnus. During its course it is surround- 
 ed by a large quantity of adipose cellular tissue, but has no ac- 
 companying vessel.* 
 
 Collateral Branches of the Cheat Sciatic. — The great sciatic 
 nerve gives off in the thigh five muscular and three articular 
 branches ; they sometimes arise separately, sometimes by a 
 common trunk. They are the following : 
 
 The nerve for the long head of the biceps, which divides into two 
 ascending branches for the origin of that muscle from the ischium, 
 and descending branches, which run for a long time in front of the 
 muscle, and then enter it by a series of filaments. 
 
 The nerve for the semi-tendinosus, which runs upon the anterior 
 surface of the muscle, and does not enter it until it reaches the 
 lower third of the thigh. 
 
 The nerves for the semi-membranosus are two in number ; they 
 almost always anastomose and enter the internal surface of the 
 muscle at two different points. 
 
 A nerve for the adductor magnus, which runs forward and then 
 inward, and enters near the inner border of the muscle. We 
 have seen that the adductor magnus receives most of its nerves 
 from the obturator nerve. All the preceding branches arise from 
 the upper part of the sciatic nerve, opposite to the quadratus femo- 
 ris, and often by a common trunk. 
 
 A nerve for the short head of the biceps sometimes arises at the 
 same height as the preceding, but is most commonly given off 
 from the sciatic nerve at the middle of the thigh. When the sci- 
 atic nerve divides prematurely, the branch we are now descri- 
 bing comes from the external popliteal. This nerve enters the 
 upper extremity of the muscle, expanding into diverging fila- 
 ments. 
 
 An articular nerve of the knee, which often arises by a common 
 trunk with the preceding, and is not unfrequently given off from 
 the external popliteal ; it passes vertically downward in front of 
 the great sciatic nerve, through some adipose tissue, to gain the 
 outer side of the joint ; having arrived above the external con- 
 dyle, it turns and divides into several filaments, which perforate 
 the fibrous tissue of the joint, and are distributed to the articular 
 adipose tissue, where they are scattered, some above, others be- 
 low, and others on the outer side of the patella, t 
 
 The External Popliteal Sciatic or Peroneal J^erve. 
 
 The external popliteal sciatic, external popliteal, or peroneal nerve 
 {i,fig. 293), the external terminal branch of the great sciatic, is 
 intended for all the muscles of the anterior and external region of 
 the leg, and for the skin on the leg and on the dorsum of the foot. 
 It is scarcely half the size of the internal popliteal ; it runs obliquely downward and out- 
 ward, behind the external condyle of the femur through the popliteal space, and is pla- 
 ced nearer to the surface than the internal popliteal nerve, which is lodged in the inter- 
 condyloid fossa ; it then crosses obliquely over the origin of the outer head of the gas- 
 trocnemius, passes behind the head of the fibula, from which it is separated by the ori- 
 gin of the soleus, turns horizontally upon the neck of that bone (at v), between it and the 
 peroneus longus, and expands into four branches, two superior or recurrent, for the tib- 
 ialis anticus, and two inferior and larger, which form the true terminations of the nerve. 
 
 Collateral Branches. 
 During this course, the external popliteal nerve gives off two superficial collateral 
 
 * In three instances I have found the great sciatic accompanied by a large vein, which was continuous with 
 the popliteal vein, and perforated the upper part of the adductor magnus, like the profunda artery. In two of 
 these cases the sciati* nerve divided at its exit from the pelvis. I did not note the arrangement of the nerve 
 in the third case. It was a remarkable circumstance that there was another popliteal vein accompanying the 
 artery : in one of the cases the vein was in front instead of behind the artery. t See note, p. 812. 
 
 5K 
 
810 NEUROLOGY. 
 
 nerves : a saphenous nerve, which we shall call the peroneal saphenous^ to distinguish it 
 from the tibial saphenous, and the peroneal cutaneous branch. 
 
 The Peroneal Saphenous Nerve. 
 
 The peroneal saphenous nerve {n) presents many varieties in different subjects, both in 
 regard to its size and origin. It is generally smaller than the tibial saphenous (/), of 
 which it may be regarded as an accessory ; it arises in the popliteal space, descends 
 vertically beneath the fascia, between the external and internal popliteal nerves, perfo- 
 rates the fascia opposite the middle of the leg, to join the external saphenous vein, 
 with which it runs along the tendo Achillis, and terminates upon the outer side of the 
 OS calcis. During this course, it gives off" several cutaneous filaments and a communi- 
 cating branch to the tibial saphenous nerve : this branch is of considerable size, and 
 comes off" while the nerve is still beneath the fascia. Having become very slender after 
 giving these branches, the peroneal saphenous nerve subdivides opposite the lower part 
 of the tendo Achillis, and upon the outer side of the os calcis, into several calcaneal 
 branches, one of which turns obliquely round the posterior surface of the os calcis, while 
 the others descend vertically, are reflected upon the under surface of that bo^e, and are 
 distributed to the skin of the heel. Not unfrequently the peroneal saphenous nerve gives 
 off a malleolar branch, which passes between the external malleolus and the skin, and 
 anastomoses in front of the ankle-joint {y,fig. 291) with a twig from the muscuJo-cuta- 
 neous nerve. This malleolar branch, which often comes from the last-mentioned nerve, 
 is, moreover, remarkable, like all nerves which are subjected to strong pressure, for its 
 thickness, its grayish colour, and, lastly, for its knotted, and, as it were, ganglionated 
 appearance. 
 
 The peroneal saphenous nerve is often very small, and is lost in the skin upon the 
 middle of the leg : its place is then supplied in the lower two thirds of the leg by the tib- 
 ial saphenous nerve, the size of which is always in an inverse ratio to that of the pero- 
 neal saphenous. 
 
 No nerve presents more varieties than the peroneal saphenous ; they relate to its size 
 and to the point at which it anastomoses with the tibial saphenous. One of the most 
 remarkable varieties is that in which the peroneal and tibial saphenous nerves, those call- 
 ed communicating saphenous branches {communicans fibula, n; communicans tibia, I) unite 
 in the popliteal space into a single trunk, the external saphenous {p), the distribution of 
 which corresponds to the ordinary distribution of the two nerves. 
 
 The Peroneal Cutaneous Branch. 
 This comes off from the external popliteal nerve, behind the outer condyle of the fe- 
 mur, passes vertically downward along the fibula, in contact with the skin, and divides 
 into ascending and descending branches, the latter of which may be traced as far as the 
 lower part of the leg. 
 
 The Terminal Branches of the External Popliteal J^erve. 
 The Branches for the Tibialis Anticus. 
 
 The two superior or recurrent branches, resulting from the subdivision of the external 
 popliteal, pass horizontally inward, behind the extensor communis digitorum, and are 
 distributed to the tibialis anticus ; one of these branches supplies the peroneo-tibial ar- 
 ticulation. 
 
 The Musculo-cutaneous Branch, or External Peroneal Nerve 
 
 The musculo-cutaneous branch {x,fig. 291), the lowest of the terminal branches of the 
 external popliteal, is intended for the muscles of the externail region of the leg, and for 
 the skin upon the dorsum of the foot (pretibio-digital, Chauss. ; peroneus externus, Saemm.). 
 
 It passes at first obliquely, then vertically downward in the substance of the peroneus 
 longus, turns forward to enter between the extensor longus digitorum and the peroneus 
 longus and brevis, and perforates the fascia of the leg, above the ankle-joint : having 
 thus become sub-cutaneous, it passes obliquely downward and inward, following the di- 
 rection of the extensor longus digitorum, becomes flattened and widened, and divides a 
 little below the tibio-tarsal articulation into an internal and an external branch ; the lat- 
 ter subdivides into three other branches, so that there are in all four terminal branches, 
 which form the dorsal collateral nerves of the toes. 
 
 Not unfrequently the musculo-cutaneous nerve bifurcates as it escapes from beneath 
 the fascia of the leg, and its two branches reunite opposite to the tibio-tarsal articula- 
 tion, so as to describe an elongated ellipse. 
 
 Collateral Branches. — There are two branches for the peroneus longus, of which one 
 comes off from the nerve immediately after its origin, while the other arises lower down, 
 and runs a very long course in the substance of the muscle ; there is also a branch for 
 the peroneus brevis,' which often arises by a common trunk with the preceding. 
 
 In its sub-cutaneous portion, the musculo-cutaneous nerve supplies several filaments 
 to the skin, among which we should distinguish an external malleolar filament, which passes 
 between the external malleolus and the skin, increases considerably in size, and becomes 
 
THE ANTERIOR TIBIAL NERVE, ETC. 811 
 
 grayish and knotted, like all nerves subjected to pressure. This filament often anastomo- 
 ses with the malleolar branch of the peroneal saphenous nerve, and sometimes supphes 
 the place of that malleolar branch. 
 
 Terminal Branches. — There are four terminal branches of the musculo-cutaneous nerve, 
 distinguished numerically as the first, second, third, and fourth (see^^. 291). The^r«( 
 or internal branch passes very obliquely forward and inward, to form the internal dorsal 
 collateral nerve of the great toe ; this nerve, like all nerves subjected to pressure, increas- 
 es in size and becomes grayish, and, as it were, knotted opposite the metatarso-phalan- 
 gal articulation. The second branch, which often arises by a common trunk with the 
 first, supplies the external dorsal collateral nerve of the great toe, and the internal collateral 
 nerve of the second toe. The third branch supplies the external collateral nerve of the sec- 
 ond, and the internal collateral nerve of the third toe. These two large branches are 
 often replaced by one (») from the anterior tibial nerve, with which they anastomose. 
 The fourth terminal branch or internal branch supplies the external dorsal collateral nerve 
 of the third, and the internal dorsal collateral nerve of the fourth toe. 
 
 All the filaments from these branches are distributed to the skin upon the dorsal re- 
 gion of the foot and digital phalanges. 
 
 In a great number of subjects, the tibial or external saphenous nerve supplies the in- 
 ternal collateral nerve of the little toe, and the external collateral nerve of the fourth 
 toe ; but in others, these nerves are furnished by an additional terminal branch of the 
 mosculo-cutaneous nerve ; in all cases the nerves anastomose with each other. 
 
 The Anterior Tibial, or Interosseous Nerve. 
 
 The anterior tibial or interosseous nerve (v v,fig. 291), intended for the muscles on the 
 anterior region of the leg, for the extensor brevis digitorum, and for the interosseous 
 muscles in the foot, is as large as the musculo-cutaneous nerve just described ; it runs 
 to the inner side of that nerve, beneath the extensor communis digitorum, and passes 
 along the interosseous ligament, together with the anterior tibial artery lying in front of 
 that vessel. It is placed, like the artery, between the tibialis anticus and the extensor 
 communis digitorum, from which it is separated below by the extensor proprius pollicis 
 pedis ; it supplies a great number of filaments to all these muscles, passes with the ar- 
 tery under the annular ligament of the tarsus, in the sheath of the extensor proprius pol- 
 licis, and divides into two branches : 
 
 The internal deep branch of the dorsum of the foot (v), which is the true continuation of 
 the nerve, passes horizontally forward, under the arteria dorsalis pedis, over the first in- 
 terosseous space, gives off a small twig to the muscles of that space, and divides into 
 two branches, which form the deep external dorsal collateral nerve of the great toe, and the 
 internal dorsal collateral nerve of the second toe. These branches communicate with the 
 superficial dorsal branches of the musculo-cutaneous nerve, and sometimes supply their 
 place. 
 
 The external and deep nerve of the dorsum of the foot runs outward between the tarsus 
 and the extensor brevis digitorum, in which it terminates ; it gives off in front, opposite 
 the interosseous spaces, a series of very delicate filaments, which enter the posterior 
 extremities of those spaces. The filaments for the fourth and fifth spaces often arise 
 by a common trunk. They are extremely delicate, and are closely applied to the tarsus. 
 
 The Internal Popliteal Sciatic^ or Tibial JVerve. 
 
 The internal popliteal sciatic, internal popliteal, or tibial nerve (h, fig. 293), is intended 
 for all the muscles of the back of the leg, and for the skin of the sole of the foot ; both 
 in direction and size it appears to be the continuation of the great sciatic nerve. It pass- 
 es vertically downward in the inter-condyloid fossa of the femur ; it is at first placed be- 
 tween the heads of the gastrocnemius, it then passes under that muscle and under the 
 arch formed by the soleus, descends, under the name of the posterior tibial nerve {k), be- 
 tween the soleus and the deep layer of muscles, inchnes a little inward, and, having 
 reached the termination of the fleshy belly of the soleus, gains the inner side of the ten- 
 do Achillis ; lower down, it passes behind the internal malleolus, against which it is flat- 
 tened and widened, and divides into the internal and external plantar nerves (a, b, and c, 
 /«■• 294). 
 
 In the popliteal space it is sub-aponeurotic, in the fleshy portion of the leg it is sep- 
 arated from the fascia by the double layer formed by the gastrocnemius and the soleus, 
 and it again becomes sub-aponeiirotic along the tendo Achillis. It is in relation, in 
 front, with the popliteal and posterior tibial vessels, which separate it, above, from the 
 knee-joint and popliteus muscle, and lower down, from the deep layer of muscles in the 
 leg.* Behind the internal malleolus, and under the groove upon the os calcis, it is en- 
 closed in a common fibrous sheath with the posterior tibial vessels, which are placed in 
 front of it ; this sheath is behind that for the tendons of the tibiahs posticus and flexor 
 communis digitorum. 
 
 * [The nerve is at first at a short distance to the outer sid« of the artery ; lower down it lies immediately 
 behind the vessel, and still lower croises to the imier side of the artery, and is separated from it by the vein.] 
 
NEXJEOLOGY. 
 
 Its coilaieral 'IfrancMs are very numerous. I shall div'de them info Itliose ^ven'ra^dp- 
 posite the knee-joint, and those supplied along the leg. 
 
 The Collateral Branches of the Internal Popliteal Jferve, behind the Knee- Joint. 
 
 These are six in number, namcl}', two anterior, which are very small, one for the 
 plantaris longus, and one for the knee-joint ; two internal, namely, the tibial saphenous 
 nerve, and the nerve for the inner head of the gastrocnemius ; two external, namely, the 
 nerve for the outer head of the gastrocnemius, and the nerve for the soleus. 
 The Tibial Saphenous Nerve. 
 
 This is generally known as the external saphenous. It is much larger than the pero- 
 neal saphenous, which always anastomoses with it. I have already said that the mode 
 and situation of this anastomosis present many varieties. The tibial saphenous nerve 
 {communicant tibia, I, Jig. 293) arises in the popliteal space, passes vertically downward 
 between the two heads of the gastrocnemius, and then upon their posterior surface, 
 along their fibrous septum, between them ; it is here situated in a small fibrous canal 
 common to it and to a small artery and vein ; it receives, at a variable height in the leg, 
 a more or less considerable filament from the peroneal saphenous nerve (or communicans 
 fibulce, n) ; it then becomes sub-cutaneous, forming the external saphenous nerve (p), 
 runs along the outer side of the tendo Achillis, just as the posterior tibial runs along its 
 inner side ; it now accompanies the external saphenous vein, which is accompanied 
 above this point by the peroneal saphenous nerve ; it is reflected behind the external 
 malleolus, in the same manner as the tibial nerve is reflected upon the internal malleolus, 
 then runs forward and downward {y,fig. 291) upon the outer side of the os calcis, where 
 it gives off several very large external calcaneal nerves, and terminates difTerently in va- 
 rious subjects. In some it terminates by forming the dorsal collateral nerve of the fifth • 
 toe ; in others it is larger, and divides into two branches, of which the external forms the 
 external collateral nerve of the fifth toe, while the internal, which receives an anasto- 
 motic branch from the musculo-cutaneous nerve (z), passes horizontally forward, crosses 
 the extensor brevis digitorum, and the tendons of the long extensors, and divides into 
 two secondary branches, of which one constitutes the internal dorsal collateral nerve of 
 the little toe, and the other the external dorsal collateral nerve of the fourth toe. I may 
 point out the thickening, the gray colour, and the knotted, and, as it were, ganglionated 
 structure of the external collateral nerve of the little toe opposite to the articulations. 
 
 The cxtertMl calcaneal nerves, which may be regarded as forming the termination of 
 the tibial saphenous, are very remarkable ; they pass vertically along the outer side of 
 the OS calcis, expand into several filaments, which are reflected upon the ridge which 
 separates the external from the inferior surface of that bone, and are distributed to the 
 skin upon the heel. 
 
 During its course along the leg, the tibial saphenous gives off scarcely a single fila- 
 ment, but along the outer border of the foot it supplies a great number, which run down- 
 ward and forward, and terminate in the skin covering the external plantar region. 
 
 The size of the tibial saphenous nerve is inversely proportioned to that of the pero- 
 neal saphenous and musculo-cutaneous nerves. Thus, when the peroneal saphenous 
 nerve is large, it furnishes most of the external calcaneal branches ; and when the mus- 
 culo-cutaneous nerve is large, it supplies, besides the external calcaneal, the internal 
 dorsal collateral nerve of the little toe, and the external dorsal collateral nerve of the 
 fourth toe. 
 
 The Nerves for the two Heads of the Gastrocnemius and for the Soleus. 
 
 The nerve for the inner head of the gastrocnemius often arises by a common trunk 
 with the tibial saphenous ; again, the nerves for the outer head of the gastrocneniius 
 and for the soleus often arise by a common trunk : the nerves for the gastrocnemius en- 
 ter the anterior surface of the head of that muscle, and immediately ramify. The nerve 
 for the soleus is the largest, and enters the muscle at its upper arch ; all these nerves 
 ramify as soon as they enter the muscles which they supply. 
 
 The Articular Nerve and Nerve for the Plantaris Longus. 
 
 The posterior articular nerve of the knee runs forward to enter the posterior ligament 
 of the articulation : one of its filaments follows the direction of the internal articular ar- 
 tery, and is lost in the popliteus.* 
 
 * [From the dissections of Mr. EUjs, it appears that there is an articular nerve to the knee-joint with each 
 articular artery. The superior external articular nerve is the one described at p. 809 ; it most commonly 
 arises from the extertial popliteal. The inferior external articular also arises from the external popliteal, and 
 sometimes from the ioiatic nerve ; it is a long branch which descends towards the external condyle, passes be- 
 low it on the outer side of the joint, and perforates the capsule. The superior internal articular is very small, 
 and is not constant ; it arises from the internal popliteal nerve, and passes on the outer side, and then in front 
 of (t. e., deeper than) the popliteal vessels, and reaches with its artery the inner side of the joint. The infe- 
 rior internal articular is the largest of all : it arises from the internal jiopliteal above the joint, descends on the 
 outer side, and then in front of the popliteal vessels, is applied to the corresponding artery upon the popliteus 
 muscle, passes beneath the mternal lateral ligament, and enters the inner side of tlie joint. The posterior ar- 
 ticular, or azygos, is given off opposite the joint from the internal popliteal, or from the inferior internal ar- 
 ticular ; it perforates the postferior ligament. — {Ellis's Demonstrations of Anatomy, p. 675, 67(1.)] 
 
THE INTERNAL PLANTAR NERVE. 
 
 813 
 
 Tlie nerve for the ■plantaris longus always arises separately from the posterior tibial 
 nerve, and immediately dips into the substance of the muscle. 
 
 Collateral Branches of the Internal Popliteal Jferve in the Leg. 
 
 There are three sets of collateral branches given off by the posterior tibial nerve in 
 the leg: namely, the nerve for the popliteus ; the nerves for the deep layer of muscles ; 
 the internal calcaneal nerve. Lastly, several very small filaments come off from the 
 nerve, run along the posterior tibial artery, and, after a course of variable length, perfo- 
 rate the aponeurosis and ramify in the skin. 
 
 The nerve for the popliteus arises opposite the knee-joint, runs forward on the outer 
 side of the popliteal vessels to gain the lower border of the muscle, around which it 
 # turns ; before entering the muscle, the nerve expands into several branches, all of 
 which pass horizontally forward opposite to the interosseous ligament, which they ap- 
 pear to perforate. But with a little care it is seen that almost all of these filaments are 
 lost in the muscle. I have, however, seen one of them perforate the interosseous liga- 
 ment together with the anterior tibial artery, and then, leaving that vessel, return 
 through the substance of the ligament, and terminate in the tibialis posticus ; several 
 filaments of the popliteal nerve are also evidently distributed to the peroneo-tibial artic- 
 ulation, and to the periosteum of the tibia and fibula. 
 
 The nerves for the deep layer of muscles of the leg consist of two sets. The nerve for the 
 tibialis posticus almost always arises by a coimnon trunk with the preceding, runs down- 
 ward and forward, is applied to the posterior surface of the muscle, to which it gives a 
 series of filaments from its anterior aspect ; the continuation of the nerve enters the 
 muscle about its middle, and maybe traced in it as far as its lower part. The nerves for 
 the flexor longus pollicis and for the flexor communis arise by a common trunk a little be- 
 low the preceding ; the nerve for the flexor longus pollicis, which is larger than those 
 for the flexor communis and tibialis posticus, accompanies the peroneal artery as far as 
 the lower part of the leg. 
 
 The Internal Calcaneal Nerve. — ^This is a large branch which comes off from the inner 
 side of the posterior tibial nerve, and which, in cases of premature bifurcation of that 
 nerve into the internal and external plantar, comes from the externeil plantar ; it passes 
 vertically downward, on the inner side of the os calcis, and divides into two diverging 
 branches, which are applied to the inner side of the bone, are reflected upon its lower 
 surface, and are distributed to the skin of the heel, one in front, and the other behind. 
 
 The Terminal Branches of the Internal Popliteal Jferve. 
 The Internal Plantar Nerve. 
 
 The internal plantar nerve, which is intended for the muscles and skin of the sole ol 
 the foot, is larger than the external plantar ; at its origin it is situated behind the inter- 
 nal malleolus, in front of the posterior tibial vessels, which cross it at an acute angle, 
 and occupies a groove which is common to it and to those vessels, and which is quite 
 distinct from and lies behind the groove for the tendons. It is reflected beneath the in- 
 ternal malleolus, becomes horizontal, reaches the calcaneal groove, perforates the pos- 
 terior extremity of the flexor brevis digitorum, and during this passage through the 
 groove is protected by a fibrous canal, which is subjacent to the grooves for the tendons. 
 
 At its exit from this fibrous canal, the internal plantar nerve is situated upon the 
 
 boundary, between the internal and middle plantar regions, between 
 the flexor brevis pollicis on the inside, and the flexor brevis digi- 
 torum on the outside ; having given off a considerable branch (a, 
 fig. 294), which becomes the internal plantar collateral nerve of the 
 great toe, it perforates the aponeurosis of the flexor brevis digitorum 
 to enter the same sheath as that muscle, and runs (J) along its in- 
 ner border. Having reached the posterior extremity of the meta- 
 tarsal bones, it divides into three branches, which form the collateral 
 nerves of the toes. Sometimes there is a fourth branch (d), which 
 passes outward, to anastomose with the external plantar nerve. 
 
 The collateral branches are very numerous. Some of them are 
 cutaneous, and perforate the plantar fascia to ramify in the skin. 
 The most remarkable are, a small calcaneal cutaneous nerve, which 
 crosses the posterior tibial vessels, to supply the skin upon the in- 
 ner side of the os calcis ; and s. plantar cutaneous nerve, which emerges 
 between the flexor brevis pollicis and the flexor brevis digitorum, 
 and divides into two small cutaneous branches, one of which pro- 
 ceeds forward, while the other runs backward, like a recurrent 
 nerve. There are cilso some muscular collateral branches, namely, 
 far the flexor brevis pollicis, the abductor pollicis, and the flexor brevis 
 digitorum. Lastly, the internal plantar collateral nerve of the great 
 toe {a), which is so large that it might be regarded as a terminal 
 branch of the internal plantar nerve ; it comes off from the last- 
 
 Fig. 294. 
 
 I 
 
814 NEUROLOGY. 
 
 named nerve, at its exit from the covered canal formed for it by the flexor brevis poUicis, 
 passes forward along the outer side of the tendon of the flexor longus poUicis, below, i. e., 
 superficial to the inner portion of the adductor poUicis (oblique adducteur, Crnveilhier), 
 and gains the inner and under surface of the metatarso-phalangal articulation of the 
 great toe ; in this place it is situated in the furrow between the internal and external 
 sesamoid bones of that articulation ; it runs forward below the inner border of the former, 
 and then of the second phalanx of the great toe, and, having arrived below that bone, it 
 divides, like the collateral nerves of the fingers, into two branches, the one dorsal or un- 
 gual, and the other plantar. 
 
 The terminal branches of the internal plantar nerve are three in number, and are distin- 
 guished as the first, second, and third, counting from within outward. i 
 
 The first terminal branch, which is the largest, runs along the outer side of the tendon 
 of the flexor longus poUicis, gives filaments to that muscle, passes between the meta- 
 tarso-phalangal articulations of the first and second toes, under an arch which is com- 
 mon to it and the corresponding vessels, and divides into two secondary branches, which 
 form, the external collateral nerve of the great toe, and the internal collateral nerve of the 
 second toe. Not unfrequently this branch gives an anastomotic filament to the internal 
 coUateral nerve of the great toe, which passes beneath the metatarso-phalangal articu- 
 lation of that toe. 
 
 The first terminal branch of the internal plantar nerve gives off the filament for the 
 first lumbricalis ; it then supplies several articular twigs to the metatarso-phalangal artic- 
 ulation of the great toe, and a very numerous series of cutaneous filaments. 
 
 The second terminal branch, much smaller than the preceding, passes somewhat out- 
 ward, crossing below, i. e., superficial to the flexor tendon of the second toe, and then 
 forward, and bifurcates opposite the metatarso-phalangal articulations, to constitute the 
 external plantar collateral nerve of the second toe, and the internal plantar collateral nerve 
 of the third. 
 
 During its course, this branch supplies filaments to the second lumbricalis, to the meta- 
 tarso-phalangal articulation of the second toe, and also to the integuments. 
 
 The third terminal branch passes very obliquely outward, crosses below the flexor 
 tendon of the third toe, and bifurcates to form the external collateral nerve of the third and 
 the internal collateral nerve of the fourth toe. 
 
 This branch supplies the metatarso-phalangal articulations of the third and fourth toes, 
 and the corresponding integuments. 
 
 Summary. — The internal plantar nerve, therefore, supplies branches to the skin on the 
 inner part of the sole of the foot, also the plantar collateral nerves of the first, second, 
 and third toes, and the internal collateral nerve of the fourth toe, aU of which are cu- 
 taneous branches. 
 
 It gives muscular branches to the flexor brevis poUicis, the abductor poUicis, the flexor 
 brevis digitorum, and to the two internal lumbricales. 
 
 Lastly, it gives off a great number oi articular filaments to the tarsal, tarso-metatarsal, 
 metatarso-phalangal, and phalangal articulations. 
 
 The External Plantar Nerve. 
 
 The external plantar nerve (c, fig. 294), which is smaller than the internal, is placed 
 with it in the groove of the os calcis, and perforates the flexor brevis, under an arch dis- 
 tinct from that for the internal plantar, and which is common to it and the external 
 plantar vessels ; it then runs downward and outward, between the flexor brevis and flexor 
 accessorius, is reflected forward, and divides into two branches, a superficial and a deep. 
 
 Collateral Branches. — During its course, the external plantar nerve gives off, immedi- 
 ately after its origin, one large branch, which runs horizontally outward, in front of the 
 tuberosities of the os calcis, passes under the flexor accessorius, and is reflected for- 
 ward to enter the abductor minimi digiti. At the point of its reflection, it gives off a 
 transverse branch, which is lost in the posterior attachment of the muscle. The exter- 
 nal plantar also supplies the nerve or nerves for the flexor accessorius. 
 
 Terminal Branches. — The superficial terminal branch (c, fig. 294), which is the continu- 
 ation of the trunk of the nerve, divides into two others, one external, the other internal. 
 
 The external branch passes very obliquely outward, below the flexor brevis digiti min- 
 imi, crosses the tendon of the abductor brevis obliquely, then runs along the outer side 
 of the fifth metatarso-phalangal articulation, and forms the external collateral nerve of the 
 little toe. It supplies a great number of cutaneous nerves, also the nerves for the_^ea;or 
 brevis digiti minimi, those for the interosseous muscles of the fourth space, and, lastly, 
 some articular filaments. 
 
 The internal branch passes forward, below the flexor tendon, foUowing the original di- 
 rection of the superficial branch of the external plantar, and, after a rather long course, 
 bifurcates to form the internal collateral nerve of the little toe, and the external collateral 
 nerve of the fourth toe ; hke the external branch, it also gives off some cutaneous and ar- 
 ticular nerves. 
 
 The deep terminal branch of the external plantar passes above, i. e., deeper than the 
 
THE EXTERlPrAt PLA>rTAR NERVE. 81§ 
 
 flexor accessorius, changes its direction, so as to describfe an arch, having its concavity 
 turned inward and backward, and the convexity outward and forward, enters, together 
 with the external plantar artery, above which it is situated, between the adductor polli 
 cis and the interossei, and is lost in the former muscle. 
 
 Before reaching the adductor pollicis it gives off some articular filaments to the meta 
 tarsal and tarso-metatarsal articulations, and also a filament for the fourth lumbricalis. 
 Beyond the adductor pollicis the nerve gives off the ^amcw^ /or the third lumbricalis ; this 
 filament, which is remarkable for the length of its course, passes horizontally forward, 
 opposite to the third interosseous space, and passes through the fibres of the transversus 
 pedis, to reach its destination ; it then gives off the filaments for the transversus, and 
 those for the interosseous muscles of the third, second, and first spaces. 
 
 Summary of the External Plantar Nerve. — The external plantar nerve, therefore, sup 
 plies cutaneous filaments to the outer side of the sole of the foot, to the fifth toe, of which 
 it forms both collateral nerves, and to the fourth toe, of which it forms the external col- 
 lateral nerve. It also gives off muscular nerves to the flexor accessorius, the flexor bre- 
 vis, and abductor digiti minimi, to the adductor pollicis, and transversus pedis, to all the 
 interossei, and to the two external lumbricales. Lastly, it furnishes some articular 
 filaments. 
 
 Summary of the Nerves of the Lower Extremity. — The lower extremity is supplied with 
 nerves from the lumbar and sacral plexuses. 
 
 The Lumbar Plexus. — The lumbar plexus gives almost all its branches to the lower 
 extremity, viz., the external and internal inguinal nerves, the obturator nerve, and the 
 crural nerve ; the lumbo-sacral cord is also distributed to the lower extremity through 
 the medium of the sacral plexus. 
 
 The external and internal inguinal nerves are the principal cutaneous nerves of the 
 anterior and external regions of the thigh ; the obturator nerve is a muscular nerve in- 
 tended for the obturator externus, the three adductors, and the gracilis.* 
 
 The crural nerve is a musculo-cutaneous nerve which supplies the following parts : 
 its cutaneous portion is distributed to the skin upon the anterior region of the thigh, 
 upon the internal region of the leg, and internal dorsal region of the foot ; its muscular 
 portion supplies all the muscles of the anterior region of the thigh ;t it also gives several 
 articular nerves to the hip and knee joints. 
 
 The Sacral Plexus. — The sacral plexus is entirely distributed to the lower extremity, 
 excepting the internal pudic nerve and certain rectal and vesico-prostatic branches in 
 the male, and rectal, vaginal, and uterine branches in the female. 
 
 The obturator internus, the pyriformis, the gemelli, and the quadratus femoris, are 
 each provided with a special nerve from the sacral plexus ; the glutaeus medius and min- 
 imus, and the tensor vaginae femoris, are especially supplied by the superior gluteal 
 nerve, and the glutaeus maximus by the inferior gluteal or lesser sciatic nerve. The 
 last-named nerve also furnishes the cutaneous nerves of the posterior region of the thigh. 
 
 The great sciatic is the nerve of the posterior region of the thigh, and of the entire 
 leg and foot. It supplies all the muscles of the posterior region of the thigh ; thus, its 
 external popliteal or peroneal division supplies the muscles of the external region of the 
 leg by its musculo-cutaneous branch, and the muscles of the anterior region by its in- 
 terosseous branch ; it also supplies the external region of the leg, and the dorsal region 
 of the foot. 
 
 Its internal popliteal or tibial division supplies all the muscles of the posterior region 
 of the l6g, the skin upon the internal and external calcaneal regions, and that upon the 
 external dorsal region of the foot. 
 
 Of its terminal branches, the internal plantar nerve is distributed to the muscles of the 
 internal plantar region of the foot, to the flexor .brevis digitorum, to the two internal 
 lumbricales, and to the skin of the internal plantar region ; lastly, it gives off the col- 
 lateral branches of the toes, excepting the two for the fifth toe, and the external collat- 
 eral branch of the fourth. 
 
 The external plantar nerve is distributed to the muscles of the external plantar region, 
 to the flexor accessorius, to all the interossei, to the two external lumbricales, to the 
 adductor pollicis and transversus pedis, and to the skin of the external plantar region : 
 it also gives the internal and external collateral nerves of the fifth toe, and the external 
 collateral nerve of the fourth. 
 
 Comparison of the Nerves of the Upper and Lower Extremities. 
 The lumbo-sacral plexus, which supplies the whole of the lower extremity, precisely 
 corresponds to the cervico-brachial, which supplies the- upper extremity. The lumbar 
 corresponds to the cervical, and the sacral to the brachial plexus. The connexion, or 
 sort of fusion of the cervical with the brachial plexus, and of the lumbar with the sacral 
 plexus, explains why it is found, on comparing the nerves of the upper and lower extrem- 
 
 * [The obturator also supplies part of the pectineus, and sometimes gives cutaneous branches to the thigh 
 ,»nd leg, and an articular filament to the knee (see note II, p. 800).] 
 fAnd also a few filaments to the iliaciu, psoas, and pectineus.] 
 
816 NEUROLOGY. 
 
 ity, that several of the nerves arising from the brachial plexus are represented by nerves 
 from the sacral plexus, and that several of those from the cervical plexus have their 
 representatives in nerves derived from the lumbar plexus. It will be seen, moreover, 
 that this analogy ought not to be carried too far, and that it is necessary, in making the 
 comparison, to exclude all nerves which belong to peculiar organs in both regions. 
 Thus, the phrenic, occipital, and auricular nerves, branches of the cervical plexus, have 
 no representatives in the lower extremity, nor is there any nerve in the upper extremity 
 corresponding to the internal pudic. 
 
 On the other hand, there is no objection to admitting that the external and internal 
 inguinal nerves in the lower extremity are represented by the clavicular nerves in the 
 upper extremity. 
 
 The crural nerve, a branch of the lumbar plexus, has no corresponding branch in those 
 of the cervical plexus, but its muscular branches are represented by the brachial portion 
 of the musculo-spiral nerve, and its cutaneous branches by the internal brachial cutane- 
 ous. The crural nerve, in fact, supplies the muscles which extend the leg upon the 
 thigh, in the same way that the musculo-spiral nerve supplies the muscles which ex- 
 tend the forearm upon the arm ; the internal saphenous nerve supplies the skin of the 
 leg, just as the internal brachial cutaneous is distributed to the skin of the forearm. 
 
 The obturator nerve, which supplies the adductors of the thigh, is represented by the 
 thoracic nerves and the nerve for the latissimus dorsi, which supply the pectoralis ma» 
 jor and latissimus dorsi, the adductor muscles of the arm. 
 
 The gluteal nerves are analogous to the supra-scapular and circumflex nerves. The 
 superior gluteal, which is distributed to the glutaeus medius and minimus, corresponds 
 to the supra-scapular, which belongs to the supra- and infra-spinatus ; and the inferior 
 gluteal or lesser sciatic nerve, which supplies the glutaeus raaximus and the skin of the 
 thigh, corresponds to the circumflex nerve, which is distributed to the deltoid, and the 
 skin of the arm. 
 
 The trunk of the great sciatic nerve represents by itself the musculo-cutaneous, the 
 ulnar, and the median nerves, and the musculo-spiral in the forearm. 
 
 The muscles of the anterior region of the arm, that is to say, the muscles that flex the 
 forearm upon the arm, receive their branches from the musculo-cutaneous nerve, just as 
 the muscles of the posterior region of the thigh, or the flexors of the leg upon the thigh,, 
 receive theirs from the great sciatic. 
 
 The external popliteal nerve represents the musculo-spiral in the forearm : the former, 
 supplies the muscles of the anterior and external regions of the leg, while the latter is 
 distributed to the muscles of the posterior and external regions of the forearm ; the for- 
 mer gives off the dorsal cutaneous nerves of the foot, and the latter furnishes the dorsal 
 cutaneous nerves of the hand. 
 
 The internal popliteal nerve represents the median and ulnar nerves together. The 
 muscles of the posterior region of the leg are supplied by the internal popliteal, as the 
 muscles of the anterior region of the forearm are supplied by the median and the ulnar. 
 
 The internal popliteal nerve completes the series of dorsal cutaneous nerves of the> 
 foot, just as the ulnar nerve completes the dorsal nerves of the hand. 
 
 Lastly, the internal plantar nerve gives off all the plantar collateral nerves of the toes,; 
 excepting those for the little toe, and the external plantar collateral of the fourth toe ; 
 it therefore represents the palmar portion of the median nerve ; and so the external plan- 
 tar represents the palmar portion of the ulnar nerve, and completes the series of plantar 
 collateral nerves. .; 
 
 THE CRANIAL NERVES. 
 
 Definition and Classifi/:ation. — The Central Extremities of the Cranial Nerves — viz., of. 
 the Olfactory — of the Optic — of the Common Motor Oculi — of the Pathetic — of the Tn-^ 
 geminal — of the External Motor Oculi — of the Portio Dura and Portio Mollis of the Sev- 
 enth — of the Glosso-pharyngeal, Pneumo-gastric, and Spinal Accessory Divisions of the 
 Eighth — and of the Ninth Nerves. 
 
 The cranial nerves are those which pass through the foramina in the base of the cra- 
 nium, not those which arise from the brain, as the rather generally adopted terms cere- 
 bral nerves and encephalic nerves would seem to indicate. 
 
 We shall follow Willis and the majority of anatomists in admitting nine pairs of cra- 
 nial nerves, which are almost indifferently named, either numerically, from the order of 
 their origin, counting from before backward, or they are named from their distribution 
 and uses. The following exhibits their nomenclature upon both principles : 
 First pair, or olfactory nerves. 
 Second pair, or optic nerves. 
 Third pair, or common motor nerves of the eyes. 
 Fourth pair, or pathetic nerves, nervi trochleares. 
 Fifth pair, or trifacial nerves, nervi trigemini 
 
CENTRAL EXTREMITY OP THE OLFACTORY NERVE. 817 
 
 Sixth pair, or external motor nerves of the eyes, nervi abducentes. 
 
 c. »u • J -J J • * ( portio mollis, or auditory nerve, 
 Seventh pair, divided mto { ^^-^ ^^^^^ ^^ f^^i^, ^^^^ 
 
 I pneumogastric nerve, or par vagum. 
 
 Eighth pair, divided into < glosso-pharyngeal nerve, 
 
 ( spinal accessory nerve of Willis. 
 
 Ninth pair, or hypoglossal nerve. 
 
 Scemmering has introduced the following modification of this nomenclature. He has 
 divided the seventh pair into two, viz., the facial nerves, which form his seventh pair, 
 and the auditory nerves, which he calls the eighth ; and then he has divided the eighth 
 pair into three others, namely, a ninth pair formed by the glosso-pharyngeal nerves, a 
 tenth formed by the pneumogastric nerves, an eleventh by the spinal accessory nerves ; 
 the hypoglossal nerves, therefore, constitute his twelfth pair. 
 
 This modification is founded on the separation of nerves so completely distinct as the 
 fiicial and the auditory, which have only been described together because they enter the 
 same canal in the base of the cranium, namely, the internal auditory meatus. 
 
 Still, this modification is a useless one, and it has the greater inconvenience of render- 
 ing the language employed obscure, from giving a double acceptation to the same terms. 
 
 It would be more philosophical to name and describe the cranial nerves from behind 
 forward, so that the hypoglossal nerves would constitute the first pair, and the olfactory 
 the last. 
 
 The indisputable analogy which exists between the posterior cranial and the spinal 
 nerves, and, moreover, the example of J. F. Meckel, would fully warrant this innovation 
 Nevertheless, I think it right to retain the old usage, and to proceed from before back- 
 ward, in the enumeration as well as in the description of the nerves. 
 
 As the origins or central extremities of all the cranial nerves and their course within 
 the cranium can be studied upon the same brain, I have thought it right to describe, in 
 one article, all these origins or central extremities, which will mutually illustrate each 
 other by their differences and their anadogies ; the experience of the dissecting-room 
 proves, moreover, that, from want of a sufficient number of brains to study the origin of 
 each nerve in particular, this part of anatomy is generally neglected. 
 
 The Central Extremities of the Cranial Nerves. 
 
 Dissection. — Two preparations are required, namely, a brain removed from the crani- 
 um, together with the origins of the nerves perfectly preserved ; and the base of a crani- 
 um, together with those parts of the brain which are near the origin of the nerves. The 
 first will serve for the examination of the central extremities of the nerves ; and the sec- 
 ond for tracing their course within the cranium. 
 
 While the origin of all the spinal nerves is uniform and regular, that of the cranial 
 nerves appears to be subject to no rule ; so that the cranial nerves diflfer as much from 
 each other in regard to their origin as they differ collectively from the spinal nerves in 
 the same particular. We shall see presently, however, that the origins of all but the 
 special nerves of the head may, to a certain extent, be referred to the same law of double 
 roots (one of which is ganglionic) which presides over the origin of the spinal nerves. 
 
 The Central Extremity of the Olfactory JVerve. 
 
 The olfactory nerves, or the first pair of cranial nerves (nerfs ethmoidaux, Chauss., 1, 
 fig. 276) are two bands, composed of white and gray substance, which arise from the 
 hindermost convolution of the anterior lobe of the brain, run forward in the anfractuosity 
 already described as the anfractuosity of the olfactory nerves, and expand in the ethmoidal 
 groove into a sort of ganglion or bulb, from which filaments are given off to be distribu- 
 ted to the pituitary membrane. 
 
 In regard to their central extremity and their course within the cavity of the cranium, 
 the olfactory nerves are singular, and their peculiarities justify the uncertainty which 
 has for a long time prevailed, and still prevails, concerning their true character. The 
 old anatomists did not regard them as nerves, but as prolongations of the brain, named 
 by them caruncula: or processus maxillares, and believed to be intended to drain off the 
 mucosity of that organ : it was Massa, according to Sprengel, and Zerbi, according to 
 Haller, who first connected them with the other cranial nerves as the first pair. Com- 
 parative anatomy, which probably suggested to the older anatomists the opinion which, 
 they held concerning these nerves, has now caused some doubts as to the propriety of 
 considering them as nerves, and has given rise to the opinion that they are the repre- 
 sentatives of the olfactory lobes of the lower animals.* Without entering here into dis? 
 cussions which belong to philosophical anatomy, let us examine the most remarkable- 
 circumstances connected with the origin and cranial course of this nerve. 
 
 Apparent Origin. — The olfactory nerves arise from the cerebrum, and this is a char- 
 
 * When speaking of the comparative anatomy of the brain, it was mentioned that in a great number of anK 
 mals there existed, in front of the cerebral lobes or hemispheres, a pair of lobes (olfactory lobes), which were- 
 ^.ontinuous with the nerves distributed to the pituitary membrane, and the development of which oorresponde<li 
 to the size of those nerves, and to the relative state of perfection of the sense of smell. 
 
 5L 
 
i^m 
 
 NEUROLOGY. 
 
 acter which belongs exclusively to them ; they are the only cerebral nerves, properly so 
 called. 
 
 They arise from the hindermost convolution of the anterior lobe, in front of the ante- 
 rior locus perforatus {h,fig. 276), which is situated behind that convolution. This origin 
 consists of a mammilla or pyramidal enlargement, gray pyramid, which is regarded as the 
 gray root of the nerve. This grayish enlargement, which can be very well seen by re- 
 flecting the nerve backward, is prolonged as a linear tract of gray substance upon the 
 upper surface of the nerve. 
 
 Besides this gray enlargement or origin, which was so well described by Scarpa, there 
 are two or three white roots, or, rather, certain white striae, very accurately represent- 
 ed by Vicq d'Azyr ; these are the external- or long root, which is concealed in the fissure 
 of Sylvius, and appears to me to arise from the posterior lobe [middle lobe] of the cere- 
 brum, or, more exactly, from the posterior lip of the fissure of Sylvius ; and the internal 
 or short root, which arises from the innermost convolution of the anterior lobe and joins 
 the long root at an acute angle ; between these roots we often see one, two, or even 
 three striae, which come from the back part of the anterior lobe. It would be both use- 
 less and tedious to describe all the varieties of this origin. 
 
 Real Origin. — Anatomists have not confined themselves to the investigation of the 
 apparent origin of the olfactory nerves, but have also endeavoured to ascertain their 
 deep or real origin. Willis described them as arising from the medulla oblongata, Rid- 
 ley from the corpus callosum, Vieussens, Winslow, and Monro from the corpora striata.* 
 
 If, after the example of Scarpa, a transverse perpendicular section of the brain be 
 made opposite the junction of the gray and white roots of the olfactory nerves, or if a 
 stream of water be directed upon the pyramidal mammilla above described, or, lastly, if 
 Herbert Mayo's method be adopted, and the origin of this nerve be examined in a brain 
 hardened in alcohol, it will be seen that, besides the white superficial striae, there are a 
 great number of deep and diverging white roots, which appear to me to come from the 
 anterior commissure, and not from the corpus striatum.! 
 
 It would follow, therefore, that the olfactory nerves arise by a commissure like the 
 optic nerves. 
 
 Cranial Course. — Having arisen in this manner by a sort of bulb or gray enlargement 
 {enlargement or bulb of origin), the olfactory nerve immediately tapers, and is received 
 into the antero-posterior sulcus intended for it, which conducts it as far as the ethmoidal 
 groove or fossa {I, fig. 296), where it forms an enlargement or bulb, named the ethmoidal 
 bulb, which is analogous in many respects to its bulb of origin. 
 
 When seen from below, the olfactory nerve has the appearance of a soft, smooth band, 
 grooved longitudinally along the middle. t 
 
 But, on reflecting the nerve backward, it is found to be prismatic and triangular, that 
 its two lateral surfaces are concave and correspond to the convolutions which bound the 
 antero-posterior sulcus for the nerve, and that its upper ridge is formed by a Unear tract 
 of gray matter which connects the gray substance of its bulb of origin with that of the 
 ethmoidal bulb. 
 
 The arachnoid has a peculiar arrangement in relation to this nerve : instead of im- 
 mediately forming a sheath for it, the arachnoid passes below it, and maintains it in 
 contact with its protecting sulcus ; while the pia mater passes above it, and lines the 
 sulcus. The nerve is not entirely separated from the brain until about a few lines from 
 the ethmoidal bulb. 
 
 In the human subject the olfactory nerve is not hollow in its centre, as in the mam- 
 malia ; when hardened by alcohol, it may be decomposed into white parallel fibres, ex- 
 actly similar to the fibres of the white substance of the brain. 
 
 The Ethmoidal Bulb or Enlargements. — The olfactory nerves, converging towards each 
 other, reach the ethmoidal fossae, where each immediately expands into an olive-shaped, 
 ash-coloured, and extremely soft bulb (the ethmoidal bulb, I, fig- 276), to which Mala- 
 carne first applied the term ganglion, and which is formed in the following manner : 
 The white filaments of which the olfactory band or prism is composed spread out like a 
 palm branch as they are about to enter the bulb, and dip into the gray or ash-coloured 
 substance, which occupies the intervals between them : this substance is precisely anal- 
 ogous to the gray matter of the brain, but is less consistent ; it also resembles the sub- 
 stance of the nervous ganglia, so that Scarpa does not hesitate to regard the ethmoid 
 bulb as a ganglion. From this enlargement are given off" the olfactory nerves properly 
 so called, which seem as if they were pressed through the foramina of the cribriform 
 
 * Chaussier, ■who adopted the latter opinion, called the corpora striata the olfactory lobes, in contradistinc- 
 tion to the optic thalami, which he terms the optic lobes. But comjiarative anatomy shows that there is nc 
 relation in point of development between the corpora striata and the olfactory nerves. 
 
 t Scarpa says th«t the deep roots come from a white cord placed in front and below the corpora striata. 
 Herbert Mayo, in his beautiful plates, has represented these roots as coming from the corpora striata. 
 
 % Willis ami Santorini have noticed this groove. Scarpa has observed three grooves, which he regards as 
 
 con-esponding to as many lines of gray substance. M. Hippolyte Cloquet {Anat. Descript., t. ii., p. 88) goes 
 
 still farther than Scarpa, and describes seven longitudinal strise, three of which are gray, and four white. 
 
 Scarpa has very justly remarked, that the proportion of ash-coloured or gray substance is much more consid- 
 
 "^ble in the ftetus, that it diminishes in the adult, and that it scarcely, if at all, exists in the old smbject 
 
CENTRAL EXTREMITY OP THE OPTIC NERVE. 819 
 
 plate of the ethmoid bone. It is said that the gray matter sends prolongations through 
 these foramina, bul this has not been demonstrated. 
 
 The Central Extremity of the Optic J^erve. 
 
 The optic nerves, or second pair (2, Jig. 276), present certain peculiarities in their tex- 
 ture, and in their cranial course, which distinguish them from all other nerves. 
 
 They have this peculiar character, that they arise by a commissure (the optic com- 
 missure), or, rather, the two optic nerves unite before they pass to their respective des- 
 tinations. 
 
 On turning the cerebellum forward, it is seen that the optic tracts (2, fig. 295) are 
 continuous with the corpora geniculata externa (i), and, consequently, take their origin 
 from the optic thalami (a), of which these bodies are a dependance. In some cases, 
 the white riband-like band, or optic tract, which constitutes the origin of the optic nerve, 
 is also continuous with the corpus geniculatum internum (c). In the human subject, the 
 optic nerves never arise, either entirely or in part, from the anterior tubercula quadri- 
 gemina (nates) ; it is only by induction that this mode of origin has been admitted in the 
 human subject.* 
 
 The optic tract (2, fig. 272), having arisen from the corpus geniculatum externum 
 (above i), with which it is continuous, without any other line of demarcation excepting 
 the difference of colour, assumes the appearance of a thin and broad riband, which turns 
 round the cerebral peduncle (v), parallel to and on the inner side of the great transverse 
 fissure of the brain. During this course, it lies in contact with the peduncle of the cere- 
 brum, from which it may be separated without laceration, excepting at its outer border, 
 by which it adheres so intimately that the peduncle has been supposed to supply it with 
 several roots. 
 
 As soon as it gets beyond the peduncle, the optic tract (», fig. 276) is condensed into 
 a flat cord, which leaves the peduncle, passes inward and forward, and unites with its 
 fellow of the opposite side to form the chiasma (square space of Zinn, t), or, rather, to 
 form, with the optic tract of the opposite side, a commissure which is convex in front 
 and concave behind. 
 
 On leaving the commissure, it completely changes its direction (2), passing forward 
 and outward, to enter almost immediately into the optic foramen (2, fig. 296). 
 
 During its course in front of the peduncle of the cerebrum, it is in relation with the 
 following parts : behind, with the tuber cinereum (v), from the interior of which some 
 white fibres arise, and pass to the chiasma ; in front, with the membrane which forms 
 the anterior portion of the floor of the third ventricle, and which is prolonged upon the 
 upper surface of the chiasma. ^ 
 
 An important question here presents itself, viz.. Is there a cOTlplete or partial decus- 
 sation of the optic nerves in the commissure 1 Do these two nerves irterlace without 
 decussating, or, rather, is there an intimate mixture of their fibres 1 Are the nerves 
 placed in simple juxtaposition and united by a transverse band 1 Lastly, does the chi- 
 asma constitute a commissure in wliich the two optic tracts terminate, or, rather, which 
 serves as a point of origin for the optic nerves T All these opinions have found sup- 
 porters, and facts have been quoted in favour of each ; a circumstance which proves, 
 not that there are anatomical varieties in the structure of the chiasma, but that its struc- 
 ture is of a complex nature. 
 
 Comparative anatomy proves that the optic nerves decussate in the commissure : in 
 fishes, the two nerves cross without uniting : it is also proved by pathological facts ; in 
 a great number of cases of atrophy of one eye, atrophy of the nerve extended, beyond 
 the commissure, to the opposite optic tract. 
 
 On the other hand, in an equally large number of cases of atrophy of one eye, the dis- 
 ease affected the optic tract of the same side, so that this would seem to show that there 
 was no decussation. 
 
 Lastly, in all cases of atrophy ctf one eye, the disease affects one of the optic nerves 
 in particular, but the other has always appeared to me to be evidently reduced in size. 
 
 On attempting to determine the point, either by the dissection of optic nerves harden- 
 ed in alcohol, or unravelled by means of a stream of water, it is seen that these nerves 
 present the following threefold arrangement at the commissure : The external fibres of 
 
 * The origin of the optic nerves varies in the different classes of animals. In birds, in which these nerves 
 are at their maximum development, they arise entirely from the tubercula quadrigeraina, which are the optic 
 lobes in these animals, and are transposed from the side to the base of the brain. The optic thalami do not 
 assist in forming these nerves. In rodentia, a small number of fibres from the optic thalami join the mass of 
 those which are derived from the nates. In canUTora, the number of filaments from the tubercula quadri- 
 gemina and from the optic thalami are almost equal. Moreover, if it be remembered that the tubercula quad- 
 rigemina, the corpora geniculata externa ai^ i|lt0ma, and the optic thalami th^iulves, belong to the same 
 system of organs, and form a continuation of th^'te-enforcing fasciculi (faisceimtSl^mnis) of the medulla ob- 
 longata ; and if other facts confirmatory of the preceding also be taken into conside^n^n, namely, that a white 
 band proceeds on each side from the natis to the corpus geniculatum exter""- -"■'< tnother from the testis to 
 the corpus geniculatum internum, it wiU be easy to account for these vu n. which can all be re- 
 
 duced to the same type. It is of some importance in regard to this quf ' great number of ciases 
 
 of atrophy of the optic nerve, which I have had occasion to examine in t! - jeo'i tl"- coipus t'cnicu- 
 
 'itum was affected, and not the natig. 
 
 dl 
 
820 NEUROLOGY. 
 
 the commissure do not decussate ; the internal fibres (and these are the most numerous; 
 do decussate ; and the posterior fibres are continued from one side to the other like a 
 commissure. 
 
 Structure. — The optic nerve has a peculiar structure. It does not commence by fila- 
 ments of origin or distinct cords, like the other nerves, but the optic tracts and the optic 
 commissure are composed of two medullary bands, the fibres of which are parallel and 
 in immediate contact with each other, precisely as in the olfactory nerves, and in the 
 cerebral substance ;* after leaving the commissure, the optic nerves are enveloped in a 
 neurilemmatic sheath, from the internal surface of which certain prolongations or septa 
 are given off, which divide the interior of the nerve into longitudinal canals, in which the 
 medullary substance is contained. 
 
 I'he optic nerve, therefore, does not consist, like other nerves, of a plexiform group 
 of nervous filaments or cords, but of a collection of canals dosely applied to each other, 
 so that it has the appearance of the pith of the rush ; hence, doubtless, the opinion of 
 Eustachius and some other authors who conceived that the optic nerve was traversed 
 by canals ; and hence, also, the error of Reil, who, having taken the structure of the op- 
 tic nerve as the type of that of all nerves, regarded each nervous cord as containing a 
 central canal, t 
 
 The Central Extremity of the Common Motor JVerve of the Eye. 
 
 The apparent origin of the motor nerves of the eyes (3, fig. 276), motores oculorum, com- 
 mon oculo-muscular nerve, or third pair, have a penicillate character ; these origins con- 
 sist of a linear series of very delicate filaments proceeding from the fasciculi found be 
 tween the peduncles of the cerebrum, in the depression between the pons Varolii and 
 the corpora albicantia. Some filaments converge from the cerebral peduncles them- 
 selves. t This origin extends about a line and a half, in a direction obliquely inward 
 and forward. The internal filaments of origin reach the middle line, so that Varolius 
 and Vieussens believed that the nerves of the right and left sides are continuous, and 
 xplained the simultaneous action of the two eyes by this anatomical arrangement. 
 Real Origin. — In a brain hardened by alcohol, or, still better, in the brain of a foetus, 
 Fig. 295. the filaments of origin of the nerve (3, fig. 295) can be easily 
 
 traced into the substance of the median fasciculi (d) found between 
 the peduncles of the cerebrum, and which have already been shown 
 to be prolongations of the fasciculi of re-enforcement {fai-sceaux 
 innomines) of the medulla oblongata. The filaments of the nerves 
 traverse these fasciculi in a diverging manner, and descend to 
 aJevel with the pons, beyond which I have not been able to trace 
 <ftm, on account of their slenderness and divergence. I have 
 never observed any of them running towards the corpora albican- 
 tia, and reaching the walls of the third ventricle or the anterior 
 commissure, as has been stated by some. Nor have I found that 
 they are re-enforced, as Gall believed, in the blackish substance 
 {locus niger) which separates the peduncles of the cerebrum, prop- 
 erly so called, from the prolongations of the re-enforcing fasciculi 
 of the medulla oblongata. 
 
 Cranial Course. — Having arisen in this manner, the fibres of the 
 motor oculi nerve converge into a flat bundle, which passes be- 
 tween the posterior cerebral and the superior cerebellar arteries, 
 upon which latter it is reflected : on emerging from the interval 
 between these two vessels it becomes rounded, and then passing 
 upward, outward, and forward, enters the reticular sub-arachnoid 
 cellular tissue at the base of the brain, and gains the side of the 
 sella turcica (3, fig. 296), where it enters a proper sheath formed for it by the dura mater. 
 
 The Central Extremity of the Pathetic Nerve. 
 
 The ncrvi pathetici (4, fig. 276), nerves of the superior oblique muscle of the eyes, nervi 
 trochleares, the internal and superior oculo-muscular nerves, or the fourth pair, as they are 
 variously called, are the smallest of the cranial nerves, and are as remarkable for being 
 
 * See note, p. 767. 
 
 t In most fishes, whose faculty of vision is exercised in a less transparent medium than air, the optic nerve 
 IS iformed by a membrane folded upon itself. In birds of prey, the membrane is sometimes folded like a fan, 
 sometimes like the leaves of a book. These folds are intended to increase the extent of surface, and to aug- 
 ment the power of vision. Malpighi first made this observation upon the optic nerve of some fishes. Des- 
 moulins, who has studied the point more carefully, has shown that it is in relation with the perfection of the 
 sense of sight. The same thing is also observed in the retina: thus, in the eagle, the retina presents two, 
 three, or four superimposed folds, so that each luminous ray acts upon sixteen surfaces instead of upon two. 
 
 t In fact, the exterml fflaments often arise from the inner border, and even from the lower surface of the 
 cerebral peduncle, at a certain distance from the inner border ; in this case, they do not arise from the pedun- 
 f.les, but merely pass throQgh them. The same is doubtless the case with the filaments of origin which Rid- 
 ley and Molinelli state that they have seen coming from the pons. I have never met with this origin from 
 llie pons, nor with that accessory nerve which Malacarne has described as proceeding from the upper part of 
 'lie jiedunclo of the cerebellum, turning round the border of the pons, and joining the motor oculi nerve. 
 
CENTRAL EXTREMITY OP THE TRIGEMINAL NERVE. 821 
 
 exclusively distributed to the superior oblique muscle of the eyes, as for their origin and 
 for the length of their course within the cranium. The term patheticus is derived from 
 the opinion that the superior oblique muscle is especially concerned in the expression of 
 love and of compassion. According to Bell, this nerve is the respiratory nerve of the eye. 
 
 The apparent origin of this {i,fig. 280) nerve is below the tubercula quadrigemina, on 
 each side of the valve of Vieussens, sometimes by one, sometimes by two, and even by 
 three or four roots. Occasionally there are several roots on one side, and only a single 
 root on the other. The nerves of the two sides are often united by some white streaks, 
 which form a transverse commissure ; at other times they do not arise at the same level. 
 
 Real Origin. — It has been supposed that some fibres come from the testes, others from 
 the cerebellum, and that others commence much lower down than the apparent origin ; 
 all that can be seen is, that these nerves {i,fig. 295) arise from the vdve of Vieussens, 
 to which they adhere so slightly that the least force is sufficient to detach them. 
 
 Cranial Course. — Immediately after its origin, the pathetic nerve turns forward and 
 downward, around the isthmus of the encephalon, in front of the anterior border of the 
 cerebellum, and thus reaches the base of the cranium (4, fig. 276), accompanied by the 
 superior cerebellar artery, between the fifth and third cranial nerve, but much nearer to 
 the fifth ; it then passes directly forward upon the side of the sella turcica (4, fig. 296), 
 and perforates the dura mater, considerably below the third nerve. During its whole 
 course, it is situated between the arachnoid and the pia mater, in the reticular cellular tis- 
 sue found in this region. 
 
 Wrisberg says that the right pathetic nerve is larger than the left. Ruysch states 
 that he found this nerve double, which it is difficult to believe, unless he meant to say 
 that it bifurcated at its origin. Vesalius regarded this nerve as a root of the third cra- 
 nial nerve ; other anatomists have considered it as a dependance of the fifth. 
 
 The Central Extremity of the Trigeminal J^erve. 
 
 Apparent Origin. — The trigeminal or trifacial nerves (5, fig. 276), the middle sympathet- 
 ic, or the fifth pair, are the largest of the cranial nerves, excepting the optic : they arise 
 at the sides of the pons Varolii, at the point where the pons becomes continuous with 
 the corresponding peduncles of the cerebellum, and exactly where the middle fibres of 
 the pons cross in front of the inferior, to form that peduncle, so that the fasciculi of ori- 
 gin appear to converge from a narrow slit in the pons itself. This origin (^,fig. 295) 
 consists of two roots, the large and the small root, which have a small prominence be- 
 tween them. The large or ganglionic root is a thick, fasciculated mass, which is, as it 
 were, constricted at its point of emergence, but immediately expands into a thick, flat 
 bundle, in which we may count about 100 fibres. On tearing off this bundle, all the fibres 
 do not give way opposite the same place, and a sort of mammillary prominence is left, 
 which Bichat regarded as belonging to the pons, as intended for the nerve to arise from, 
 and as having the effect of multiplying the surfaces of origin, in consequence of its con- 
 vexity. • 
 
 The small root, which is non-ganglionic, is composed of small and very distinct bun- 
 dles, which arise from the pons, above and behind the great root, by several cords ; it 
 emerges from the pons through a fissure distinct from that for the great root, and gains 
 the upper border of that root. 
 
 It will hereafter be seen that the small root has no share in the formation of the gan- 
 gliform plexus known by the name of the semilunar or Gasserian ganglion, and that it 
 goes exclusively to assist in forming the inferior maxillary division of the fifth nerve. 
 
 Real Origin. — Until modem times, the origin of the fifth nerve had not been traced be- 
 yond the point of its emergence. Late authors have described its real origin with so 
 much detail that little remains to be desired. Gall, while examining the fifth nerve, first 
 in mammalia and then in the human subject, saw that in many the origin of the nerve is 
 concealed by certain transverse fibres of the pons which do not exist in the lower ani- 
 mals. Having traced the nerve by clearing off" the fibres of the pons, he thought he ob- 
 served that the great root divided into three principal fasciculi, which he conceived arose 
 in succession from the gray matter of the pons, and which he succeeded in tracing as far 
 as to the outer side of the olivary body.* 
 
 Rolando, by successive sections made through the pons towards the medulla oblongata, 
 has clearly shown that the great root of the fifth nerve consists of only one fasciculus, 
 which runs downward and backward, under the form of a thick cord (see fig. 295), in the 
 substance of the pons, or, rather, at the boundary between the pons and the middle ped- 
 uncle of the cerebellum, parallel to the fasciculi of the anterior pyramid, and that it pro- 
 gressively diminishes in size, until it disappears opposite to the inferior angle of the fourth 
 ventricle. The examination of this origin in a brain hardened by alcohol, or, still better, 
 in the foetal brain, confirms Rolando's observations, and proves that the great root of the 
 
 * In the human subject, the origin of the fifth nerve is extremely deep-seated ; it is not so deep in the car- 
 nivora, and still more superficial in ruminantia. In oviparous animals, which have neither a pons Varolii, nor 
 lateral lobes of the cerebellum, nor pyramids, nor olivary b xiii s, the origin of the fifth pair is seen without 
 any dissection. 
 
«^ 
 
 NEUROLOGY. 
 
 ^g- 296. fifth nerve comes from the back part of the mednHa ob- 
 
 longata, from the interior of its fasciculi of re-enforce- 
 ment {faisceaux innominis).* As to the small root, it 
 cannot be traced beyond the surface of the pons.t 
 
 Cranial Course. — After emerging from the pons, the 
 fifth nerve passes upward, outward, and forward, under 
 the form of a flattened bundle, gains the upper border 
 of the petrous portion of the temporal bone {5, Jig. 296), 
 on which there is. a depression that is converted into a 
 canal for the nerve by a fold of the dura mater ; the 
 nerve is reflected upon this border, and proceeds as will 
 presently be described. 
 
 The Central Extremity of the External Motor 
 Jferve of the Eye. 
 
 The external motor nerves of the eye (6, fgs. 276, 295), 
 external oculo-muscular nerves, nervi abducentes, or the sixth pair, which are distributed 
 exclusively to the external rectus or abductor muscle of each eye, and which are so re- 
 markable for their communications with the sympathetic system, are smaller than all 
 the cranial nerves, excepting the pathetic. 
 
 Apparent Origin. — The statements of authors regarding the apparent Origin of this nerve 
 have been singularly various : some, with Morgagni, describe it as arising both from the 
 pons and the anterior pyramids ; others, with Vieussens, from the pons alone ; and others, 
 with Lieutaud, from the anterior pyramids only. Winslow states that it arises between 
 the pons Varolii and the olivary body, and Haller, that it proceeds from the furrow be- 
 tween the anterior p3rramid and the pons. 
 
 The fact is that this nerve, among some varieties of origin, presents two very distinct 
 roots (see Jig. 276) : one internal and smaller, which arises from the pons, either at or 
 near its lower border ; the other external and larger, which appears to emerge on the 
 outer side of the upper part of the anterior pyramid. These two roots are fasciculated : 
 not unfrequently some fibres are seen arising from the olivary body, or from the furrow 
 between the two p)Tamids. 
 
 Real Origin. — This is more easily seen in mammalia generally than in man. In the 
 former, Gall has traced it along the side of the pyramids. Mayo believes that the fibres 
 traverse the pons, and pass to the back part of the medulla oblongata. From the tenu- 
 ity and whiteness of the fibres of this nerve, I have not been able to trace their course 
 in the substance of the medulla. 
 
 Cranial Cmirse. — This nerve runs upward and a little outward, on the side of the basi 
 lar groove, and perforates the dura mater (6, Jig. 296) opposite to and above the apex of 
 the petrous portion of the temporal bone, to enter the cavernous sinus : the two roots of 
 the nerve often unite before perforating the dura mater, but they usually pass separately 
 through it and unite within the sinus. 
 
 The Central Extremity of the Seventh JVerve. 
 
 The central extremity of the facial nerve, or portio dura of the seventh nerve (7, Jig. 270, 
 276). The facial nerve (on the inner side of 7) arises in the deep depression between 
 the middle peduncle of the cerebellum and the pons in front of the auditory nerve (on the 
 outer side of 7) : it emerges from the front of the restiform body, under the form of a 
 fasciculated band, some fibres of which are at first situated at a distance from the gen- 
 eral mass, but soon join it ; it then turns round the lower borders of the peduncle of the 
 cerebellum, against which it is closely applied, and then becoming free, passes outward 
 and upward. It has no neurilemma up to the point where it becomes free. 
 
 The real origin of this nerve (7, Jig. 295) is much deeper ; it may be traced through 
 the restiform body into the fasciculus of re-enforcement, near the median furrow of the 
 calamus scriptorius. 
 
 The Central Extremity of the Auditory Nerve. — The auditory nerve, or portio mollis of the 
 seventh (on the outer side of 7, fig. 275), is riband- shaped, and non-fasciculated at its origin : 
 it arises (7',Jig. 295) in the same depression as the facial nerve, but behind that nerve, and 
 opposite to the restiform body : it presents two very distinct roots : an anterior, which 
 is arranged like the facial nerve ; and a posterior, which turns horizontally round the 
 back part of the restiform body, appears upon the posterior surface of the medulla ob- 
 longata (see ^o-. 271), and separates into fibres, which may be traced as far as the me- 
 
 * Vicq d'Azyr says that the roots of this nerve extend as far as the cerebellum, but this assertion has not 
 been verified. The same anatomist declares that he has often seen the fifth nerve of the right side larger than 
 that of the left. 
 
 t According to Dr. Alcock, there is a slight enlargement at the origin of the large root of the fifth nerve, in 
 the lower part of the floor of the fourth vRntricle ; he has also traced the small root to this enlargement, from 
 which he states that two cords descend, one to the anterior, the other to the posterior column of the cord.— 
 {Cyclop, of Anat. and Phys., art. Fifth Pair of Nf.rves.) 
 
CENTRAL EXTREMITY OF THE EIGHTH NERVE. 823 
 
 dian furrow of the calamus scriptorius, and which represent some of the barbs of the 
 quill. It is very generally admitted that the auditory nerves have a tranverse commis- 
 sure, but this does not appear to me to be clearly demonstrated. 
 
 The portio dura and the portio mollis of the seventh nerve, which arise so near to each 
 other, follow the same cranial course : they arise at the same height from the medulla 
 oblongata, pass outward and upward in front of the pneumogastric or sub-peduncular 
 lobule of the cerebellum, and enter the internal auditory meatus {7, fig. 296). During 
 this course, the portio dura always lies in front of the portio mollis. 
 
 The auditory nerve is the softest of all the cranial nerves ; the difference between it 
 and the facial nerve, in this respect, has led, in a great measure, to the subdivision of 
 the nerves into the soft or sensory, and the hard or motor. 
 
 The Central Extremity of the Eighth Jferve. 
 
 Of the three nerves on each side which together constitute the eighth nerve (8, figs. 
 370, 276, 295), the glosso-pharyngeal is the highest, the pneumogastric is the next, and the 
 spinal accessory is the lowest. 
 
 The Central Extremity of the Glosso-pharyngeal and Pneumogastric Nerves. — ^The glosso- 
 pharyngeal and pneumogastric nerves have a common origin. They arise, like the spinal 
 nerves, by a hnear series of funiculi (see fig. 270), which come off, not from the furrows 
 between the olivary and restiform bodies, but from the restiform body itself, on a hne 
 with the auditory nerves. Soemmering states that he has seen some of these funiculi 
 arise from the anterior wall of the fourth ventricle. 
 
 Moreover, as in the spinal nerves, each funiculus of origin is formed by the union of 
 two or three converging filaments ; the funiculi of the glosso-pharyngeal nerve, which 
 are the highest, and which come off immediately below the auditory nerve, are not dis- 
 tinct at their origin from those of the pneumogastric ; nor, as will presently be stated, 
 are the funiculi of origin of the pneumogastric distinct from those of the spinal acces- 
 sory. The division into the three nerves cannot be made until after the funiculi are 
 finally grouped. 
 
 It has been stated, but without proof, that the fibres of the glosso-pharyngeal and 
 pneumogastric nerves might be traced through the restiform body as far as the back of 
 the medulla oblongata. The funiculi of origin of these nerves, which are enveloped by 
 the neurilemma at the point where they emerge from the medulla, are so small that, 
 when torn off, scarcely any trace of their points of attachment can be detected even by 
 the aid of a lens. 
 
 The Central Extremity of the Spinal Accessory Nerve of Willis. — The origin of the spiTial 
 accessory nerve (.s,fig. 295) is quite peculiar, and has obtained much notice from modem 
 anatomists. 
 
 It arises from the sides of the cervical region of the spinal cord, between the anterior 
 and posterior roots of the cervical nerves, and behind the ligamentum denticulatum. 
 Sir C. Bell, who classes it among the respiratory nerves, strongly insists upon its ori- 
 gin from that column of the cord which is situated between the anterior and posterior 
 columns, in a line with the pneumogastric and facial nerves, which column (the respira- 
 tory tract) he assumes to give origin solely to the respiratory nerves. The funiculi of 
 origin of the spinal accessory vary much both in number and size, and are widely separ- 
 a.ted from each other : the lowest as well as the highest funiculi appear to me to be con- 
 tinuous with the posterior roots of the spinal nerves ; and, again, the -liighest are con- 
 tinuous above with those of the pneumogastric nerve, and appear to me to establish a 
 transition between the origin of that nerve and the posterior roots of the spinal nerves. 
 
 The lowest funiculus of the spinal accessory is generally situated not lower than the 
 fifth cervical nerve ; it has been seen to arise opposite the sixth, and even the seventh 
 cervical nerve ; the latter is the normal condition in the ox. 
 
 It is of importance to remark the connexion which exists between the spinal acces- 
 sory nerve and the first cervical or sub-occipital nen^e. Almost always one or two, and 
 frequently all of the posterior funiculi of the sub-occipital, join the spinal accessory. Not 
 unfrequently a small funiculus joins the spinal accessory from the second cervical nerve. 
 Opposite its connexion with the sub-occipital nerve, the spinal accessory sometimes pre- 
 sents a gangliform enlargement, which was well described by Huber (in ganglion vix 
 hordeaceum intumescit ncrvus accessorius). In some cases a filament proceeds from this 
 ganglion and joins the anterior roots of the sub-occipital nerve. Winslow believed that 
 the funicuh of origin of the spinal accessory communicated with the hypoglo.ssal : this is 
 an error. The greater number and even the whole of the funiculi of the sub-occipital 
 nerve have been seen to join the spinal accessory, in which case, filaments from the latter 
 nerve always supply the place of those which are usually furnished by the first cervical.* 
 
 The Cranial Course of the Glosso-pharyngeal and Pneumogastric Nerves. — They pass 
 horizontally outward, in contact with the lateral fibrous layer of the fourth ventricle, 
 forming two groups having a very small interval between them. The two, three, or 
 four small bundles which constitute the glosso-pharyngeal nerve pass through a special 
 
 * Lobstein, De Ntrvo Spinali. Vide Scriptor. Neurol., Minor de Ludwig., t. ii. 
 
824 NEUROLOGY. 
 
 opening m the upper part of the foramen lacerum posterius (8, Jig. 296). The bundles 
 which form the pneumogastric nerve are collected together and pass through the same 
 foramen, but by a distinct opening from the preceding one. 
 
 The cranial, or, rather, the vertebral course of the spinal accessory nerve of Willis, is re- 
 markable. This nerve, which is very small below, where it is formed by one or two 
 funiculi, ascends vertically upon the side of the cervical region of the spinal cord, to 
 which it is closely applied below, just behind the ligamentum denticulatum, and from 
 which it is separated above, where it is immediately in front of the posterior roots of the 
 cervical nerves ; it goes on increasing in size as it receives additional funiculi, which are 
 blended with it ; having arrived a few lines below the posterior lacerated foramen, it 
 passes upward and outward to enter the same opening as the pneumogastric, being situ- 
 ated below that nerve, and emerging with it from the cranium. 
 
 The Central Extremity of the Hypoglossal Jferve. 
 
 The hypoglossal nerves {9, figs. 276, 295), or ninth pair, arise on each side, from the fur- 
 row between the olivary and pyramidal bodies, in the same manner as the spinal nerves, 
 i. e., by a linear series of funiculi placed one above the other. 
 
 The furrow from which the funiculi of the ninth nerve arise is continuous with the 
 line formed by the origins of the anterior roots of the spinal nerves ; no funiculus arises 
 from the line formed by the posterior roots.* The relation of the origin of the ninth 
 nerve with the vertebral artery in front, and the vascular ramifications which surround 
 the funiculi of this origin, require to be mentioned. 
 
 The real origin of the ninth nerve cannot be traced beyond its apparent origin. It is 
 certain that no fibres come from the pyramids ; it has appeared to me that the fibres en- 
 tered the substance of the olivary bodies, in which they could not be traced to any depth. 
 
 Cranial Course. — All the funiculi of origin of the hypoglossal nerve commence by two 
 or three filaments, which are immediately covered by the neurilemma ; they are then 
 grouped into two or three bundles, which pass horizontally outward to the anterior con- 
 dyloid foramen, through which (9, fig. 296) they almost always pass separately. Thus 
 the dura mater forms two and sometimes three distinct canals for the hypoglossal nerve. 
 
 DISTRIBUTION OF THE CRANIAL NERVES. 
 
 The First Pair or Olfactory Nerves. — The Second or Optic Nerves. — The Third or Common 
 Motor Nerves. — The Fourth or Pathetic Nerves. — The Fifth or Trigeminal Nerves — the 
 Ophthalmic Division of the Fifth, and its Lachrymal, Frontal, and Nasal Branches — the 
 Ophthalmic Ganglion — the Superior Maxillary Division of the Fifth, and its Orbital Branch 
 — the Spheno-palatine Ganglion, and its Palatine, Spheno-palatine, and Vidian Branches — 
 the Posterior and Anterior Dental, and the Terminal Branches of the Superior Maxillary 
 Nerve — the Inferior Maxillary Division of the Fifth — its Collateral Branches, viz., the 
 Deep Temporal, the Masseteric, Buccal, and Internal Pterygoid, and Auriculo-temporal — 
 its Terminal Branches, viz., the Lingual and Inferior Dental — the Otic Ganglion. — The 
 Sixth Pair or External Motor Nerves. — The Seventh Pair — the Portio Dura or the Facial 
 Nerve — its Collateral Branches — its Terminal Branches viz., the Temporo-facial and 
 Cervico-fascial — the Portio Mollis or Auditory Nerve. — The Eighth Pair — its First Por- 
 tion of the Glosso-pharyngeal Nerve — its Second Portion or the Pneumogastric Nerve, di- 
 vided into a Cranial, Cervical Thoracic, and Abdominal Part — its Third Portion, or the 
 Spinal Accessory Nerve. — The Ninth Pair or the Hypoglossal Nerves. — General View of 
 the Cranial Nerves. 
 
 The First Pair, or the Olfactory Nervks. 
 
 Dissection. — Harden the nerve in dilute nitric acid. Examine the pituitary membrane, 
 not from its free surface, but from the surface which adheres to the periosteum. The 
 nerve ramifies between the periosteum and the pituitary membrane. 
 
 Before the time of Scarpa, the olfactory pedicles or bands and the ethmoidal bulb were 
 the only parts well known ; the passage of the olfactory nerves through the foramina of 
 the cribriform plate, and their distribution in the pituitary membrane, were scarcely 
 noticed. 
 
 Passage of the Olfactoy Nerves through the Cribriform Plate. — I must here remind the 
 student that the cribriform plate of the ethmoid bone is perforated by foramina, or, rather, 
 by different sets of canals which ramify in its substance ; that some of these canals ter- 
 minate directly upon the roof or upper wall of the nasal fossae, and that the others are 
 divided into an internal set, which pass along the septum and end by becoming grooves, 
 and an external set, which descend on the superior and middle turbinated bones, and on 
 the rough quadrilateral surface in front of them. 
 
 The olfactory nerves arise from the ethmoidal bulb {I, figs. 296, 297) by a considera- 
 
 * tin the ox and dog Mayer discovered a small posterior root with a ganglion for this nerve ; and he states 
 that he once found a small posterior root on one side in the human subject.] 
 
THE OPTIC NERVES. 825 
 
 Ftg 297. ^^^ number of white bundles, which immediately pass through the 
 
 " cribriform plate, and divide and ramify {i.,jig. 297) in the same 
 
 way as the bony canals themselves ; the dura mater forms a 
 sheath for each of the subdivisions of the nerve, and supports 
 their soft substance. All these nervous filaments are distributed 
 upon the septum (cZ) and upon all the external wall (a, fig. 299) of 
 each nasal fossa ; the anterior run forward, the middle vertically 
 downward, and the posterior backward. Some of them only in- 
 terlace as they leave the cribriform plate. They all expand into 
 very delicate pencils. They are situated between the periosteum 
 and the pituitary membrane, and none of them reach either the 
 inferior turbinated bone, or the maxillary, sphenoidal, or ethmoidal sinuses ; on the inner 
 wall of each fossa they do not pass lower than the middle of the septum ; and on the 
 outer wall they do not descend below the middle turbinated bone.* 
 
 With regard to the ultimate termination of the fibres of the olfactory nerve, there has 
 been a difference of opinion ; some believe that they terminate in papillae like those of 
 the skin ; and others imagine that they expand into a membrane, like the optic nerve in 
 the retina and the auditory nerve in the membranous labyrinth. I have never seen 
 them terminate otherwise than by pencils of extremely delicate filaments very closely 
 apphed to each other. 
 
 Function. — The olfactory nerves are the essential organs of smell. Their distribution 
 proves that the sense of smell resides essentially and exclusively in the roof of the nasal 
 fossae and the immediately adjacent parts. 
 
 The Second Pair, or the Optic Nerves. 
 
 The optic nerves have already been described from their origin to the optic commis- 
 sure, and from the commissure to the optic foramina (2, Jig. 296) ; they pass through 
 these foramina together with the ophthalmic arteries which are below them ; they are 
 also accompanied by a sheath formed by the dura mater and by a prolongation of the 
 arachnoid, the latter being immediately reflected from them. 
 
 The optic nerve, which is flattened up to this point, becomes rounded on emerging 
 from the optic foramen, and is received in a fibrous ring formed by the origins of the 
 muscles of the eye ; it here, also, changes its direction shghtly, for, instead of passing 
 obliquely forward and outward, it runs almost directly forward to the globe of the eye, 
 which it enters behind, and somewhat below, and to the inner side (see o, Jigs. 237, 238, 
 240). There is a very evident circular constriction at the point where the optic nerve 
 enters the eye.t 
 
 During its course in the orbit, the optic nerve is surrounded by a great quantity of 
 adipose tissue, which separates it from the muscles and nerves. The ophthalmic gan- 
 glion and the ciliary nerves and vessels are in immediate contact with it. It is accom- 
 panied, as far as the sclerotic, by a fibrous sheath given off from the dura mater, so that 
 this nerve differs from all others, in being provided with two protecting sheaths, name- 
 ly, a proper neurilemma, and a sheath formed by the dura mater. A section of the optic 
 nerve also presents throughout its course that peculiar appearance resembling the pith 
 of the rush, which we have already described as commencing at the commissure (see 
 Central Extremity of the Optic Nerve). 
 
 As it enters the ball of the eye the nerve loses its two sheaths, which appear to be- 
 come continuous with the sclerotic, and is thus reduced to its pulp, which spreads out 
 to form the retina. In some subjects the retina presents a distinctly radiated appear- 
 ance around the abrupt termination of the nerve (see Globe of the Eye — Retina). 
 
 Function. — The optic nerves are the nerves of vision ; their continuity writh the retina 
 leaves no doubt of this being their function. 
 
 The Third Pair, or the Common Motor Nerves of the Eyes. 
 
 Dissection. — All the nerves of the orbit should be studied together. The frontal and 
 lachrymal branches of the ophthalmic nerve and the fourth nerve may be first examined ; 
 then the orbital portion of the nasal branch of the ophthalmic, which will afterward be 
 traced into the nasal fossae ; next, the common and external motor nerves ; and, lastly, 
 the ophthalmic ganglion and the optic nerve. 
 
 The common motor nerve has already been traced {^,Jigs. 298, 301) from its origin with- 
 in the peduncles of the cerebrum to the side of the quadrilateral plate of the sphenoid 
 bone, below and to the outer side of the posterior clinoid process ; in this situation (3, 
 Jig. 296) it is received into a groove formed for it by the dura mater ; it then perforates 
 that membrane, enters the cavernous sinus, passes through it from behind forward and 
 
 * In mammalia, and particularly in the horse, a cord arises from the olfactory nerve, runs downward and 
 forward alon? the septum, parallel to and in front of the naso-palatine nerve, and terminates in the small in- 
 cisory cavity which exists in the arch of the palate in the lower animals, and is thought by M. Jacobson to be 
 the seat of a sixth sense. 
 
 t M.Arnold, in his beautiful plates of the nerves of the head, has represented two very delicate filament* 
 as establishing a communicativ^n between the suoorior maxillary and the optic nerves. 
 
 5M 
 
826 NEUROLOGY. 
 
 a little outward, and before entering the orbit divides into two branches of unequal size, 
 of which one is superior and the other inferior. 
 
 The following are its relations in the cavernous sinus : it is situated in the substance 
 of the external wall of the sinus, to the outer side of the internal carotid artery, above 
 the external motor nerve, and to the inner side of the fourth nerve and of the ophthalmic 
 branch of the fifth ; it enters the orbit at the innermost, and, consequently, the widest 
 part of the sphenoidal fissure. 
 
 It has no immediate relations with the other nerves that pass through the cavernous 
 sinus, until it is about to enter the orbit ; at this point it receives some very delicate fil- 
 aments from the cavernous plexus of the sympathetic, and an equally small filament 
 from the ophthalmic branch of the fifth nerve; after which, the external motor nerve* 
 becomes situated below the common motor, while the frontal and pathetic nerves cross 
 above it ; the nasal branch of the ophthalmic is in contact with its outer side, and then 
 passes between its two divisions. 
 
 As the common motor nerve passes through the sphenoidal fissure, the tendon of the 
 external rectus forms a fibrous ring around it, which is quite distinct from the ring be- 
 longing to the optic nerve ; this fibrous ring also surrounds the external motor nerve 
 and the nasal branch of the ophthalmic. 
 
 The superior terminal division of the third nerve is much smaller than the inferior ; it 
 passes below the superior rectus of the eye, and immediately expands into a great num- 
 ber of filaments, one of which is very large, and runs along the outer border of that mus- 
 cle. Almost all these filaments are intended for the superior rectus, which they enter 
 by its under surface. Several of them are very small, and run along the inner border 
 of the superior rectus, to be distributed to the levator palpebrse superioris. The fila- 
 ments for this last muscle are proportionally much smaller and less numerous than those 
 for the superior rectus. 
 
 The inferior terminal division is the true continuation of the nerve both as regards its 
 size and direction ; it runs between the optic nerve and the external motor nerve, which 
 is in contact with it, and which lies between it and the external rectus muscle, and al- 
 most immediately subdivides into three branches : an internal, which, passing beneath 
 the optic nerve, gains the internal surface of the internal rectus, and ramifies in that 
 muscle ; a median, which penetrates the inferior rectus ; and an external branch, which 
 is the smallest, and runs along the outer side of the inferior rectus as far as the inferior 
 oblique, and enters that muscle at its posterior border, and almost at right angles. The 
 short, thick filament which enters the ophthalmic ganglion proceeds from the branch for 
 the inferior oblique muscle. This filament for the ganglion sometimes arises separately, 
 and appears to be a fourth branch of the inferior division of the third nerve. t 
 
 Function. — The common motor nerve supplies all the muscles of the eye, excepting 
 the superior oblique and the external rectus. It is remarkably large, and is proportion- 
 ed to the activity and frequency of contraction in these muscles. That the muscular 
 nerves do not terminate in loops or arches may be well seen in these muscles. 
 
 The Fourth Pair, or the Pathetic Nerves. 
 
 The pathetic nerve {4:, figs. 298, 301) is remarkable for its extreme slenderness, for its 
 origin upon the side of the valve of Vieussens, for the length of its cranial portion, and 
 for its winding course around the peduncle of the cerebrum ; it enters (4, Jig. 296) an 
 opening in the dura mater upon the anterior extremity of the inner or concave border of 
 the tentorium cerebelli, on the outer side of the common motor nerve ; it runs in the sub- 
 stance of the external wall of the cavernous sinus, to the outer side and a little below 
 the level of the common motor nerve (3), and directly above the ophthalmic division (a) 
 of the fifth, to which it sends otf a filament, and then, running along the upper surface 
 of that nerve, communicates with it by several twigs ; it then enters the orbit together 
 with the frontal nerve, the principal branch of the ophthalmic, through the widest part 
 of the sphenoidal fissure, passes inward and forward, leaves the frontal nerve, crosses 
 obliquely over the superior branch of the common motor nerve and the back part of the 
 levator palpebra; superioris and superior rectus of the eye, to reach the superior oblique, 
 and, having previously ramified, enters the upper border of that muscle. During its course 
 in the orbit, this nerve, like the frontal branch of the ophthalmic, is in contact with the 
 periosteum. 
 
 The union of the ophthalmic branch and the pathetic nerve is so intimate that it has 
 been imagined that the lachrymal nerve is always derived entirely from the pathetic, and 
 not from the ophthalmic itself But a careful dissection shows that this is generally in- 
 correct. However, I have found the pathetic nerve in several subjects giving offa branch, 
 
 * It appears to me that there is a communication between the common and external motor nerves in the 
 cavernous sinus. 
 
 t I have seen the branch for the inferior rectus arise by two roots, one from the branch for tlie internal 
 rectus, and the other from the branch for the inferior oblique. I have seen the branch for the inferior oblique 
 give off a supernumerary branch to the inferior rectus. Lastly, sometimes the branches for the inferior 
 oblique and inferior rectus are united, so that the inferior division of the third nerve was subdivided into two 
 branches onlv 
 
THE TKIGEMINAL NERVES. 
 
 which united with another from the ophthalmic nerve to constitute the lachrymal nerve 
 This anastomosis took place at the bottom of the orbit. Another and well-founded view re- 
 gards the pathetic nerve and the ophthalmic branch of Willis as forming a single nerve ; in 
 fact, in certain subjects they interlace so intimately that it is impossible to separate them. 
 The Branch for the Tentorium Cercbelli. — The pathetic nerve, while still contained in 
 the substance of the external wall of the cavernous sinus, gives off a branch which runs 
 backward in the substance of the tentorium cerebelli, and may be traced as far as the 
 lateral sinus, near which it divides into two or three filaments. In several subjects I 
 found that the branch for the tentorium was formed by a twig which arose from the oph- 
 thalmic nerve, became applied to the pathetic nerve, then divergpd from it,- and passed 
 backward in the substance of the tentorium. It appears, then, that the nerve of the ten- 
 toriarti has a retrograde course.* 
 
 Function. — The fourth pair of nerves is intended for the superior oblique muscle only 
 of the eye. It has been supposed that this muscle has a special nerve to enable it to ex- 
 press certain mental emotions, and especially love and pity ; but, as Soemmering remarks, 
 it exists in all mammalia, in birds, and even in fishes. 
 
 Camper states that the vital functions of the pathetic survive those of the other nerves, 
 and that this circumstance influences the direction of the eyes in dying persons. 
 
 According to Sir C. Bell, the pathetic is the respiratory nerve of the eye. Its origin 
 is situated at the highest part of the respiratory tract. According to the same physi- 
 ologist, it is the nerve of expression ; it associates the muscles of the eye, and estab- 
 lishes certain relations between the eye and the respiratory system. 
 The Fifth P.ur, or the Trigeminal Nerves. 
 The Twrvu$ trigeminus (trifacial, Chauss., 5, fig. 296), which, as already stated, arises 
 from the side of the pons Varolii by two distinct roots, gains the upper border of the pe- 
 trous portion of the temporal bone, over which it is reflected, and near the apex of which 
 there is a depression for the reception of the nerve : a bridge-like fold of the dura ma- 
 ter converts this depression into a canal. The nerve, which increases in width as it 
 passes over the upper border of the petrous bone, continues to get wider while upon the 
 upper surface of the same bone, and runs downward, forward, and outward ; its fibres 
 inunediately spread out and interlace to enter the concave surface of a grayish semilu- 
 nar enlargement called the semilunar or Gasserian ganglion. All the fibres of origin of 
 the fifth nerve do not assist in the formation of this ganglion ; for, on reflecting the nerve 
 from within outward, a flat cord {b, fig. 299) is seen below the ganglion, and giving no 
 fibre to it ; and, on tracing this cord upon the side of the pons Varolii, it is found to con- 
 sist of the small root of the fifth nerve, which is at first placed on the inner side of this 
 nerve, and then turns round it to gain its under surface. 
 
 This very remarkable disposition estabhshes a complete analogy between the fifth cra- 
 nial nerve and the spinal nerves, which, as we have seen, have ganghonic roots (the 
 posterior roots) and non-ganglionic roots (the anterior). 
 
 The Gasserian ganglion (behind a b c, fig. 298 ; c, fig. 299) is lodged in a special de- 
 pression in the petrous portion of the temporal bone {fig. 296), and it adheres so closely 
 to the dura mater that it is impossible to separate the ganglion without tearing it. From 
 its convex surface, which is directed forward and outward, proceed three plexiform ner- 
 vous trunks, which diverge like the toes of a bird ; these are, proceeding from before 
 backward, the ophthalmic nerve of Willis (a, figs. 296, 298, &c), the superior maxillary nerve 
 (i), and the inferior maxillary nerve (c) : the non-ganglionic root (J, fig. 299) of the fifth 
 nerve goes directly to the inferior maxillary division (c) of the nerve : the opiithalmic and 
 the superior maxillary divisions often arise by a common trunk. Several scattered fila- 
 ments are given ofl!" from the three divisions of the 2i^_._ 398. 
 nerve, but soon join them again. Communicating 
 filaments are sometimes seen between the superi- 
 or and inferior maxillary divisions as these latter 
 enter their respective foramina. 
 
 The ganglionic nature of the Gasserian gangli- 
 on cannot be doubted ; for, like all ganglia, it con- 
 sists of a grayish, pulpy matter, in which the ner- 
 vous fibres are spread out, and, as it were, entan- 
 gled, to enter into new combinations. 
 
 The Gasserian gangliont gives off" several fila- 
 ments for the dura mater, which may be traced 
 into the substance of the tentorium cerebelli: a 
 <^rtain number of filaments appear to be destined 
 
 * Arnold has described the branch {f,Jig. 296) for the ten- 
 torium cerebelli, which is derived from the fifth nerve, and not 
 that which comes from the pathetic. 
 
 t The Gasserian ganglion might serve as a type for demon- 
 strating the structure of all ganglia, so easy is the separation 
 of the gray matter and white fibres. 
 
NEUROLOGY. 
 
 for that part of the dura mater which covers the petrous portion of the temporal bone 
 and the sphenoid bone. In order to demonstrate these twigs, the dura mater must bt 
 previously rendered transparent by maceration in diluted nitric acid. 
 
 The Ophthalmic Division of the Fifth J^erve. 
 The ophthalmic nerve of Willis, or ophthalmic division of the fifth nerve (nerf orbitaire, 
 Winslow; orbito-frontal, Chauss., a, fig. 296, &c.), is the highest and smallest of thfl 
 three divisions : it passes forward, outward, and upward, in the substance of the exter- 
 nal wall of the cavernous sinus, in which situation it has a plexiform structure. It is 
 there divided into an external branch, called the lachrymal nerve {e, fig. 296), a middle 
 branch, the frontal nerve (continuation of a), and an internal hranch, or the nasal nerve ; 
 these three branches enter the orbit through different parts of the sphenoidal fissure. 
 Before this division, the ophthalmic nerve gives off a retrograde filament (nervus recur- 
 rens inter laminas tentorii, Arnold, f,fig. 296), which passes backward, closely applied 
 to the twig furnished by the pathetic nerve to the tentorium cerebeUi, and running paral- 
 lel to that twig, enters the tentorium. 
 
 The Lachrymal or Lachrymo-palpebral Nerve. 
 
 Dissection. — First expose the nerve in the orbit, and then trace it backward to its ori- 
 gin. This dissection is difficult, unless the parts have been macerated in diluted nitric 
 acid. The nerve is then to be traced into the substance of the upper eyelid. 
 
 The lachrymal nerve (c, fig. 296), the smallest of the three branches of the ophthalmic, 
 comes off from the outer side of that nerve, in the substance of the external wall of the 
 cavernous sinus, where it is difficult to discover its origin and course, on account of its 
 intimate adhesion to the dura mater ; it enters the orbit through the narrowest part of 
 the sphenoidal fissure, runs along (below s,fig. 300) the upper border of the external rec- 
 tus, passes through the lachrymal gland, to which it gives several filaments, pierces the 
 fibrous layer of the upper eyelid, descends vertically within that eyelid, between its 
 fibrous layer and the orbicularis muscle, and divides into two principal cutaneous fila- 
 ments : a palpebral, which runs along the lower border of the tarsal cartilage ; and an as- 
 cending temporal, which is lost in the integuments upon the anterior temporal region. 
 During its course, the lachrymal nerve gives off a malar branch, which may be regarded 
 as resulting from a bifurcation of the nerve. This branch perforates the malar bone, 
 and anastomoses with the facial nerve upon the cheek.* 
 
 The lachrymal branches, properly so called, are extremely small. The real termination 
 of the lachrymal nerve is in the upper eyelid, and hence the term lachrymo-palpebral has 
 been given it. 
 
 I have already said that the lachrymal nerve not unfrequently arises by two filaments, 
 one of which is derived from the ophthalmic of the fifth, and the other from the pathetic 
 nerve (Mr. Swan describes this as the usual condition). In a specimen which I have 
 now before me, there are two lachrymal nerves, one of which arises in the ordinary 
 manner, that is to say, from the ophthalmic division of the fifth, while the other, which 
 is external and smaller, arises both from the pathetic and the frontal nerve. These two 
 lachrymal nerves anastomose with each other. 
 
 The Frontal Nerve. 
 
 The frontal nerve (fronto-palpebral, Chauss.) may be regarded as the continuation of 
 the ophthalmic (a, fig. 296) both in size and direction ; it enters the orbit at the highest 
 and broadest part of the sphenoidal fissure, together with the pathetic nerve. t 
 
 It passes horizontally forward, between the periosteum and the levator palpebrae su- 
 perioris, crossing that muscle at an acute angle, and divides at the bottom of the orbit 
 into two unequal branches, which do not diverge until they reach the front of that cavity ; 
 these are the internal frontal and the external frontal.X 
 
 The External Frontal or Supra-orbital Nerve (r,figs. 296, &c.). — This is larger than the 
 internal branch ; it passes out of the orbit through the supra-orbital foramen, and ex- 
 pands into ascending or frontal, and descending or palpebral branches. The palpebral 
 branches are very numerous, and descend vertically in the substance of the upper eye- 
 
 * Authors speak of a filament from the lachrymal nerve which anastomoses with the superior maxillary 
 nerve near the anterior extremity of the infra-orbital fissure. I have never seen this filament. 
 
 [Before reaching the lachrymal gland, the lachrymal nerve may give off one or two communicating filaments, 
 to join the temporal filaments of the orbital branch (t,fig. 300) of the superior maxillary nerve, before these 
 latter perforate the outer wall of the orbit.] 
 
 t The orbital nerves which enter the sphenoidal fissure are divided into two sets : those which pass thro'igh 
 the fibrous ring of the external rectus, namely, the common motor nerve, the nasal branch of the ophthalmic, 
 and the external motor nerve ; and those which pass above and to the outer side of the preceding, immediately 
 below the lesser ring of the sphenoid bone, between the periosteum and the superior rectus, namely, the fron- 
 tal branch of the ophthalmic, the pathetic, and the lachrymal branch of the ophthalmic ; the latter nerve pass- 
 es separately through the sphenoidal fissure. 
 
 X Not unfrequently a third branch arises from the inner side of the frontal nerve ; this might be called the 
 fronto-nasal ; it passes obhquely inward and forward, crosses over the superior oblique, anastomoses with the 
 external nasal nerve, emerges from the orbit below the pulley for the tendon of the superior oblique, and ter- 
 minates with the external nasal nerve in the upper eyelid. [This fronto-nasal branch may arise from the in- 
 ternal frontal nerve.] 
 
THE NASAL NERVE. 829 
 
 lid ; one of these branches runs horizontally outward under the orbicularis palpebrarum, 
 to anastomose with the branches of the facial nerve. The frontal hraiKhes are generally 
 two in number, an external and an internal. They form the true continuation of the ex- 
 ternal frontal nerve, which almost always bifurcates as it passes through the supra-orbi- 
 tal foramen ; they are reflected upward ; the external, which is the larger, passes between 
 the frontal muscle and the periosteum ; the internal {h, Jig. 285) lies between the muscle 
 and the skin ; they both run somewhat obliquely upward and outward, spread out into 
 ramifications, which diverge from each other at acute angles, and may be traced as far 
 as the lambdoidal suture. Almost all these ramifications are distributed to the skin. 
 Some of them are periosteal, and these require for their proper demonstration that the 
 parts should be macerated in diluted nitric acid : it is doubtful whether any of them ter- 
 minate in the frontal portion of the occipito-frontalis muscle. In some subjects there is 
 a very remarkable osseous frontal branch, which enters an opening in the supra-orbital fo- 
 ramen, and passes along a canal formed in the substance of the frontal bone ; it as- 
 cends vertically like the canal, gives off a succession of small periosteal filaments, and at 
 length, emerging from the canal opposite to the frontal eminence, becomes sub-cutaneous. 
 
 The Internal Frontal or Supra-trochlear Nerve is,Jigs. 296, 301). — This is almost always 
 smaller, but is sometimes as large as the external frontal ; its size appears to me to be 
 inversely proportioned to that of the external nasal and external frontal nerves togeth- 
 er ; it is often divided into two branches ; it passes out of the orbit between the supra- 
 orbital foramen and the pulley of the superior oblique (hence it is called the supra-troch- 
 lear nerve), and divides into ascending- or frontal filaments, which ramify in all that portion 
 of the integuments of the forehead which lies between the branches of the right and left 
 external frontal nerves, and into descending or palpebral and nasal filaments, which de- 
 scend vertically ; the former set in the upper eyelid, and the latter upon the dorsum of 
 the nose, where they anastomose with the branches of the nasal nerve.* 
 
 When there are two internal frontal nerves, the inner one of them enters a fibrous 
 ring formed in the upper part of the pulley for the superior oblique, and divides into pal- 
 pebral and nasal twigs, while the outer one supplies the frontal filaments. This outer 
 nerve sometimes perforates the orbital arch from behind forward in a special canal : I 
 have seen it pass from without inward to enter the frontal sinus, then run along the an- 
 terior wall of the sinus, and finally emerge through a special foramen at the side of the 
 nasal eminence. This nerve gave no branch in the sinus, although it was situated be- 
 tween its anterior wall and the lining membrane. 
 
 I have seen the frontal nerve divided, from its entrance into the orbit, into four branch- 
 es, of which the two outer ones corresponded to the external frontal, and the two inner 
 ones to the internal frontal nerve. 
 
 The Nasal Nerve. 
 
 Dissection. — The orbital portion of this nerve is easily exposed between the optic nerve 
 and the superior rectus. The external nasal branch can also be easily traced upon the 
 frontal region. In order to see the internal nasal branch in the corresponding nasal fos- 
 sa, an antero-posterior vertical section of the head must be made on one side of the sep- 
 tum nasi ; this section will also serve for the demonstration of all the deep nerves of the 
 face. 
 
 The nasal nerve (above t,fig. 301), which is intermediate in size between the other 
 two branches of the ophthalmic, viz., the frontal and lachrymal nerves, arises from the 
 inner side of the ophthalmic, sometimes even as that nerve is entering the cavernous si- 
 nus ; it is at first applied to the inner side of the ophthalmic nerve, and then to the outer 
 side of the common motor nerve, together with which it enters the orbit, passing be- 
 tween the superior and inferior branches of that nerve. It then runs inward and for- 
 ward, crosses obliquely over the optic nerve, passes below the superior rectus, then be- 
 low the superior oblique, gains the internal wall of the orbit, and divides, near the upper 
 border of the internal rectus, into two branches, named the internal and the external na- 
 sal nerve. 
 
 Before its entrance into the orbit, the nasal nerve gives off a long and slender filament 
 (sometimes two), which enters the ophthalmic ganglion ; it also furnishes one or more 
 ciliary nerves, which run on the inner side of the optic nerve, and are distributed like 
 the ciliary nerves derived from the ophthalmic ganglion. 
 
 The external nasal nerve (palpebral, Chauss.). This branch it,Jigs. 296, 301) runs for- 
 ward, following the original direction of the nerve below the superior oblique, and emer- 
 ges from the orbit by passing under the cartilaginous pulley for the tendon of that mus- 
 cle (infra-trochlearis nerve, Arnold) • it is sometimes joined by that division of the fron- 
 tal nerve which I have named the fronto-nasal (note, p. 828),t and divides into the fol- 
 lowing branches : palpebral filaments, which run downward and outward in the orbicu- 
 laris palpebrarum, and form anastomotic arches at the free margin of the upper eyelid ; 
 a great number of nasal twigs, which pass upon the dorsum of the nose, and anastomose 
 
 * [The supra-trochlear nerve supplies filaments to the cornigator sapercilii, and to the orbicularis.! 
 
 t I hare seen the external nasal nerve give off a branch which ran inward, anastomosed with the fronto-na- 
 nal, perforated the roof of the orbit, ran for about an inch beneath the dnrn mater, pcrfonited the frontal bonf 
 ab)ve and to the outer side of the frontal sinus, and was distributed to t'l ■ -i';ui up'i;i 'i ■ '•>rfhead. 
 
S30 NECROLOGY. 
 
 with the filaments of the facial nerve, which accompany the angular vein ; ani frontal 
 twigs, which anastomose with those of the internal frontal nerve.* 
 
 The Internal Nasal or Ethmoidal Nerve (u, fig. 296). — The course of this nerve is very 
 remarkable. It enters the anterior internal orbital canal, which conducts it into the eth- 
 moidal groove, on the internal surface of the basis cranii ;t it is then reflected forward 
 upon the side of llie crista gaili, passes through the ethmoidal fissure into the corre- 
 sponding nasal fossa, becomes sensibly increased in size, and divides into two filaments, 
 in internal, or nerve for the septum, and an external, or naso-lobar nerve. 
 
 The internal filament, or anterior nerve of the teptum nasi {a, fig. 297), enters the fibro- 
 mucous membrane upon the anterior part of the septum, and divides into several very 
 slender filaments, which may be traced below the middle of the septum. 
 
 The external filament, or nerve of the external wall of the nasal fossa (u, fig. 299), runs 
 along the anterior border of the septum, and divides into two terminal filaments, one of 
 which passes upon the fore part of the external wall of the nasal fossa, and ramifies upon 
 the turbinated bones ; while the other and larger filament (e, naso-lobaire, Chauss.) fol- 
 lows the original course of the nerve, and passes behind the nasal bone, which is mark- 
 ed with a groove, and frequently even by a canal for the reception of the nerve ; from 
 this latter filament several twigs proceed, which perforate the nasal bone more or less 
 obliquely, and are distributed to the skin of the nose ; having reached the lower border 
 of the nasal bone, it passes forward, increasing in size, through the fibrous tissue which 
 unites the bone to the lateral cartilage of the nose, and then ramifies in the skin cover- 
 ing the ala and lobe of the nose, where I have seen it anastomose with the facial nerve. 
 
 While within the cavity of the cranium, the internal nasal nerve lies beneath the dura 
 mater, and is perfectly distinct from the olfactory nerve, with which it never anastomoses. 
 
 The Ophthalmic Ganglion and its Branchcs.X 
 Dissection. — The ophthalmic ganglion may be exposed in several ways : for example, 
 ♦jither in dissecting the branch given by the common motor nerve to the inferior oblique 
 anuscle, or directly by removing the adipose tissue between the external rectus and the 
 »ptic nerve. The long branch from the nasal nerve to the ophthalmic ganglion and the 
 ;iliary nerves can also be exposed with the greatest ease. 
 
 The ophthalmic or ciliary ganglion (behind i,fig. 298) is a small, grayish, and flattened 
 enlargement, of a lenticular form (the lenticular ganglion), applied to the outer side of the 
 optic nerve, and situated about two or three lines from the optic foramen, in the midst 
 of a great quantity of adipose tissue, which renders its dissection difficult. It varies 
 much in size, and sometimes consists of a simple miliary enlargement, which forms a 
 point of origin and termination for a certain number of nerves. For the convenience of 
 description, this ganglion is said to have four angles, two posterior and two anterior ; 
 by its posterior and superior angle it receives a long slender branch {its long root), given 
 off from the nasal nerve while still contained within the cavernous sinus. Not unfre- 
 quently a second long, but extremely slender root, is furnished by the nasal nerve to the 
 ophthalmic ganglion. By its posterior and inferior angle it receives a short, thick branch, 
 which comes from the inferior division of the common motor nerve {its short root). From 
 its two anterior angles it gives off two small bundles of nerves, named the ciliary nervet 
 {i, fig. 298 ; x, fig. 301). Lastly, the ophthalmic ganglion has a ganglionic or soft root, or, 
 rather, a communicating filament, between this ganglion and the superior cervical gan- 
 glion of the sympathetic ; this soft root arises frohi the cavernous plexus, and passes 
 .■sometimes to the long or nasal root of the ophthalmic ganglion, and sometimes to the 
 ophthalmic ganglion itself 
 
 The ciliary nerves are remarkable for their tortuous course, in which respect they re- 
 semble the ciliary arteries ; and also for being collected into two bundles, the one supe- 
 rior, which is generally composed of four filaments, and the other inferior, composed of 
 five or six. The ciliary nerves do not anastomose before they reach the globe of the 
 eye, with the exception, however, of the ciliary nerve, which is derived directly from 
 the nasal nerve, and which anastomoses with an inferior ciliary nerve from the ophthal- 
 mic ganglion. Having reached the sclerotic, the ciliary nerves perforate the coat more 
 or less obliquely, around the entrance of the optic nerve, excepting two or three, which 
 enter the globe of the eye near the attachment of the muscle ; after having perforated 
 the sclerotic, they become flattened or riband-shaped, and run forward {a, fig. 242) par- 
 allel to each other, between the sclerotic and the choroid coats, slightly adhering to the 
 former of these membranes, on which grooves exist for their reception ; on approaching 
 the ciliary circle or ligament (h), they bifurcate, and divide into filaments, which anasto- 
 mose with the neighbouring filaments, and appear to be lost in the ciliary circle, which 
 
 * [It also supplies branches to the lachrymal sac and caruncula, and to the parts of tha inner canthns.] 
 t Not unfrequently the internal nasal nerve, while within the ethmoidal groove, gives off a recurrent net* 
 vous twig, which enters the orbit by a small canal, in front of the anterior internal orbital canal, and anasto- 
 moses with the external nasal or infra-trochlear nerve. I have seen this small nerve anastomose with the 
 tronto-nasal branch, which I have already described (note, p. 828) as an unusual branch of the frontal nerve. 
 t The connexions of the ophthalmic ganglion with the nasal nerve, as well as with the common motor nerve, 
 have induced me to describe it here. 
 
SUPERIOR MAXILLARY DIVISION OP THE FIFTH NERVE. 831 
 
 has been, and not without some reason, considered by modern anatomists as a nervous 
 ganglion, ganglion annulare (annulus gangliformis seu ganglion annulare, Sammering). I 
 have seen some of these ciliary nerves pass through the ciliary circle and enter the iris ; 
 they are not distinctly seen to enter the ciliary processes.* 
 
 The Superior Maxillary Division of the Fifth Merve. 
 
 Dissection. — Saw through the zygomatic arch, turn down the masseteric muscle, and 
 remove the roof of the orbit ; first dissect the lachrymal, malar, and temporal twigs of 
 the orbital branch of the nerve ; then clean out the orbital cavity, remove the upper wall 
 of the zygomatic fossa to reach the spheno-maxillary fossa by means of two cuts joined 
 at an acute angle in the foramen rotundum. Detach the origins of the pterygoid mus- 
 cles ; lastly, trace the nerve into the infra-orbital canal and on the face. 
 
 The superior maxillary nerve Q),figs. 298, 300, 301), the second or middle division of 
 the fifth nerve, both in position and size, runs forward to enter, after a very short course, 
 the foramen rotundum, by which it is conducted into the spheno-maxillary fossa ; from 
 thence it passes into and traverses the whole length of the infra-orbital canal, where it 
 is named the infra-orbital nerve (/) ; having reached the fore part of that canal, it bends 
 downward, and ramifies in the cheek. It is plexiform at its origin and in the foramen 
 rotundum, but is fasciculated throughout the rest of its course. 
 
 Its collateral branches, taken in the order of their origin, are the orbital nerve ; certain 
 nerves which are given off from the enlargement called Meckel's ganglion, namely, the 
 palatine, spheno-palatine, and vidian or pterygoid nerves ; the posterior dental nerves, 
 and the anterior dental nerve ; lastly, several small filaments come off either from the 
 ganglion of Meckel or from the superior maxillary nerve itself, and, surrounding the in- 
 ternal maxillary artery, assist in the formation of its plexus. 
 
 The Orbital Nerve. 
 This branch [t, jig. 300) comes off immediately in front of the foramen rotundum, from 
 the upper side of the superior maxillary nerve, passes through the spheno-maxillary fis- 
 sure, along which it proceeds to enter the orbit ; it then runs along the floor of tl>e orbit, 
 and divides into two branches : the one ascending, the lachrymal branch of the orbital 
 nerve, which enters the lower surface of the lachrymal gland, anastomoses with the 
 lachrymal branch (s) of the ophthalmic nerve (a), and sends off some branches to the 
 upper eyelid, near its external angle ; the other branch is the temporo-malar, which pass- 
 es horizontally forward, enters a small canal in the malar bone, and subdivides into a 
 malar filament, which perforates the bone, and is distributed to the skin upon the malar 
 region,! and a temporal filament, which perforates the orbital portion of the malar bone, 
 and dips into the anterior part of the temporal muscle, in which it anastomoses with the 
 anterior deep temporal nerve, a branch of the inferior maxillary. I have sometimes 
 seen two temporal filaments pass through the malar bone at two different points.^ 
 
 The Spheno-palatine Ganglion and its Branches. 
 
 After having given off the orbital nerve, and while it is still contained in the spheno- 
 maxillary fossa, the superior maxillary nerve gives off from its lower side a thick branch, 
 frequently two, and occasionally several branches, from which a great number of diver- 
 ging nerves immediately proceed ; these are the three palatine nerves, the spheno-pala- 
 tine nerves, and the vidian nerve ; at the point where these nerves diverge is found an 
 enlargement which the elder Meckel,^ whose name is connected with the description of 
 the fifth pair, regarded as a ganghon, and which is, therefore, called Meckel's ganglion, 
 or the spheno-folatine ganglion (situated before s,fig. 299 ; below b,fig. 301). 
 
 In a certain number of cases, I have sought in vain for the ganglionic structure in this 
 enlargement, i. e., for gray matter with white filaments scattered through it. It appear- 
 ed then to be nothing more than the common trunk or starting-point of a great number 
 of nerves ; in the majority of cases, however, a quantity of gray matter certainly exists, 
 but is so arranged that the nerves may generally be traced quite through the enlarge- 
 ment, so that they clearly are not given off from the ganglion itself, but come directly 
 from the superior maxillary nerve. II 
 
 * Tiedemann, from the results of observations in comparative anatomy, believes that the arteries vv'hich ram- 
 ify in the retina are accompanied by very delicate nervous filaments, derived from the ophthalmic ganglion and 
 the ciliary nerves : he has seen a nervous filament penetrate the optic nerve with the arteria centralis retinje ; 
 and he states that the ciliary arteries are accompanied by very delicate nervous filaments, which he has tra- 
 ced into the retina as far as the zone of Zinn. Tiedemann also says that he has seen, only once, it is true, a 
 rather large nervous filament proceed from Meckel's ganglion, and join the thick and short branch which is 
 pveu oflFfrom the third pair to assist in the formation of the ophthalmic ganglion. 
 
 t It is said that this twig anastomoses with the facial nerve in the malar region ; I have never been fortu- 
 nate enough to discover this anastomosis. 
 
 X [Both of these temporal filaments maybe joined by communicating twigs from the lachrymal nerve withia 
 the orbit ; one of them anastomoses with the anterior deep temporal nerve, as above mentioned ; the other, 
 having entered the temporal fossa through the malar bone, ascends on the temporal surface of that bone, turns 
 outward, perforates the temporal fascia about an inch above the zygoma, anastomoses with filaments of the 
 facial nerve, and of the auriculo-temporal branch of the inferior maxillary nerve, and is lost in the skin on the 
 temple.] t) Mem. de I'Acad. de Berlin, 1749 
 
 II In one case the ganglion of Meckel was in contact with the internal surface of the superior maxillary 
 nerve In the same case a filament proceeded from the upper part of the ganglion, and joined the branch 
 
.flB NEUROLOGY. 
 
 I shall now describe, in succession, the branches which proceed from Meckel's ganglion. 
 
 The Palatine Nerves. 
 These nBrves {gg,fig- 299; g,Jig. 301) are three in number: an anterior palatine, 
 which is the largest, a posterior palatine [the middle of some authors], which is the next 
 in size, and an intermediate nerve [the posterior of some authors], which is the smallest ; 
 these nerves are continuous with Meckel's ganghon ; it is most evident that, in the 
 greater number of cases, they arise directly from the lower part of the superior maxil- 
 lary nerve. 
 
 The anterior or great palatine nerve immediately enters the posterior palatine canal, 
 through the whole length of which it passes, and, having reached the lower orifice of 
 that canal, is reflected forward, and terminates by bifurcating on the hard palate. 
 
 During its course, it gives off an inferior nasal branch (lower f, Jig. 299), which is dis- 
 Fig. 299. tributed over the middle meatus and the middle and inferior 
 
 turbinated bones : the twig for the inferior turbinated bone 
 may be traced to the fore part of that bone ; it also gives off 
 the anterior palatine, and several small twigs, which perfo- 
 rate the inner wall of the maxillary sinus, and are distributed 
 to the last molar teeth ; lastly, at its exit from the posterior 
 palatine canal, and even sometimes while yet within that 
 canal, it sends off a staphyline branch, which spreads into 
 several filaments, all of which run backward in the soft pal- 
 ate, and divide into superior filaments distributed to the mu 
 cous membrane on the nasal surface ; and inferior, which run beneath the mucous mem- 
 brane on the buccal surface of the soft palate. Of the two terminal branches of the an- 
 terior palatine nerve, both of which occupy the hard palate, the external runs near the 
 alveolar border, and the internal near the median line ; they enter into the midst of the 
 glandular layer of the palate, and are ultimately distributed to the glands, to the mucous 
 membrane of the hard palate, and to the gums. 
 
 The posterior [middle] palatine nerve, the next in size, enters a special canal : on es- 
 caping from which it passes backward, beneath the mucous membrane of the nasal sur- 
 face of the soft palate, to which it is distributed. 
 
 The same is the case with the intermediate [posterior] or small palatine nerve, which 
 is extremely slender. 
 
 I have seen a palatine nerve enter the maxillary sinus, run beneath its lining mem- 
 brane, pass vertically through the maxillary tuberosity behind the last molar tooth, and 
 ramify upon the hard palate. 
 
 The Spheno-palatine or Posterior Nasal Nerves. 
 
 Dissection. — ^Make a vertical section of a head, previously macerated in dilute nitric 
 acid, strip off the pituitary membrane lying upon the septum and the turbinated bones, 
 and examine the nerves from the internal or deep surface of that membrane. 
 
 The spheno-palatine nerves are very slender ; they enter the corresponding nasal 
 fossae through the spheno-palatine foramen, and have been traced by Scarpa with his 
 customary exactness. They are all situated in the pituitary membrane, or, rather, be- 
 tween the periosteum and the mucous membrane, and cannot be readily seen until this 
 fibro-mucous membrane has been removed from the bones which it covers ; the nervous 
 filaments are then seen through the semi-transparent fibrous layer. For this purpose, 
 preparations macerated in diluted nitric acid are indispensable. The spheno-palatine 
 nerves are distributed to the septum nasi and the external wall of the corresponding na- 
 sal fossa ; they are divided into internal and external. 
 
 There is only one internal spheno-palatine nerve, viz., the nerve of the septum nasi, or 
 ine naso-palatine of Scarpa {b,fig. 297) ; it passes inward, in front of the sphenoidal si- 
 nus, and below the orifice of that sinus, to gain the septum nasi ; it is then directed at 
 first almost vertically downward, but afterward almost horizontally forward, as far as 
 the superior orifice of the anterior palatine canal, which it enters, and then passes into 
 a special canal, quite distinct from the anterior palatine canal, and parallel to the one 
 for the naso-palatine nerve of the opposite side. According to M. Hippolyte Cloquet, 
 the two naso-palatine nerves terminate in the upper part of a ganglion, which he calls 
 the naso-palatine, and do not reach the mouth ; but in some researches which I have 
 made on the subject, I have failed in detecting this ganglion. t 
 
 The nerves can be distinctly seen to enter the mucous membrane of the hard palate 
 behind the incisor teeth, and upon that prominence of the mucous membrane against which 
 the point of the tongue is so often applied. I have never seen any anastomoses either 
 between the two naso-palatine nerves, or between these and the anterior palatine nerves. 
 
 given by the external motor nerve to the sympathetic. I have not been able to discover the filaments which 
 are said to establish a communication between Meckel's ganglion and the optic nerve. 
 
 t I find that it is stated by Arnold, whom I have so often quoted, because his works are above all praise fijr 
 their rigorous accuracy, that the spheno-palatine ganglion docs not exist ; and he observes, with reason, that 
 the subjoined description of M. Hippolyte Cloquet is very imperfect. " It consists of a small , reddish, fungous 
 mass, rather hard, as if fibro-cartilaginous, and surrounded by adipose cellular tissue " 
 
THE PTERYGOID NERVE, ETC. 833 
 
 Anatomists are not agreed as to whether the naso-palatine nerve gives off any fila- 
 ments upon the septum. I have failed in detecting any ramification of the nerve in a 
 great number of preparations, in which tlie pituitary membrane had been rendered trans- 
 parent by long maceration in diluted nitric acid. Rather frequently a filament was given 
 off from the upper part of the nerve, and then joined it again. Three times only did I 
 observe a twig running upward from the anterior part of the nerve. 
 
 The external spheno-palatine, or superior nasal nerves (upper /, fig. 299), so called to 
 distinguish them from thfe inferior nasal branch of the anterior palatine nerve, are three 
 or four in number ; they are directed vertically along the back part of the outer wall of 
 the corresponding nasal fossa, and spread out into filaments, which extend over the tur- 
 binated bones and the meatus ; these filaments can only be seen from the deep surface 
 of the pituitary membrane.* 
 
 I have never been able to find the anastomoses between the internal and external 
 spheno-palatine nerves and the divisions of the olfactory nerve, which are admitted by 
 some anatomists. 
 
 The Vidian or Pterygoid Nerve. 
 
 The vidian nerve {v,figs. 300, 301) arises from the back part of Meckel's ganglion, and 
 enters the vidian or pterygoid canal, after emerging from which it perforates the carti- 
 laginous plate of the foramen lacerum anticus, and divides into a superior cranial branch, 
 the great superficial petrosal nerve, and an inferior, deep, or carotid branch. The subdivis- 
 ion of the pterygoid nerve often occurs at its origin from Meckel's ganglion. 
 
 The inferior or carotid branch, which is much larger than the superior, forms the con- 
 tinuation of the nerve : it enters the carotid canal, and is applied to the outer side of 
 the carotid artery, where it anastomoses with the nerves which establish a communica- 
 tion between the superior cervical ganglion and the external motor nerve of the eye, 
 and assists in the formation of the carotid plexus ; a flattened gangliform enlargement 
 is seen at the point of anastomosis. I have sometimes seen two carotid branches, one 
 of which was very small. 
 
 The superior or cranial branch, the great superficial petrosal nerve, enters the cranium 
 between the temporal and sphenoid bones, runs backward and outward {v, fig. 296) be- 
 neath the dura mater, in a groove on the upper surface of the petrous portion of the 
 temporal bone, passes through the hiatus Fallopii into the aqueductus Fallopii or canal 
 for the facial nerve (part of 7), and anastomoses with that nerve. t I say that it anasto- 
 moses, because there is a sort of fusion of the two nerves, and not a simple juxtaposi- 
 tion. The branch called the chorda tympani, which comes off from the facial nerve at 
 some distance from the point of fusion, should not be regarded as a prolongation of the 
 superficial petrosal nerve, supposed in that case to be merely applied to the facial nerve.t 
 
 The Posterior Dental Nerves. 
 
 Dissection. — These nerves can be readily seen without any dissection through the 
 bone, when this is rendered transparent by nitric acid. They must be examined both 
 from the external surface of the bone, and from the interior of the sinus. 
 
 The posterior dental or alveolo-dental nerves (e,figs. 298, 300, 301) are two in number, 
 a superior and an inferior ; sometimes there are three ; they arise from the superior 
 maxillary nerve, sometimes by a common trunk, sometimes separately, just as that 
 nerve is about to enter the infra-orbital canal : they run forward and downward, at first 
 in contact with the maxillary tuberosity, and give off some filaments to the buccinator 
 muscle, and to the gums, and some which are distinctly distributed to the mass of fat in 
 the cheek ; they then enter certain canals in the substance of the maxillary tuberosity, 
 and become flattened or riband-shaped. 
 
 The posterior and superior dental nerve passes from behind forward, through the base 
 
 * Bock, and Arnold after him, have described, under the name of the pharyngeal branch, a rather large 
 branch, which may be regarded as belonging to the external spheno-palatine nerves ; it enters into the ptery- 
 go-palatine canal, formed between the under surface of the sphenoid and the sphenoidal process of the palate 
 bone, passes backward and inward, and divides into several filaments, which are distributed to the upper part 
 of the pharynx. [Some of these superior nasal branches are said to supply the lining membrane of the pQS<.e- 
 rior ethmoidal and the sphenoidal sinuses.] 
 
 t I have seen the superior branch of the vidian formed by three very distinct filaments: anatomists are still 
 undecided as to whether the inferior or carotid branch is derived from the ganglion of Meckel, or from tlie su 
 perior cervical ganglion. According to Arnold, it resembles the organic system of nerves in its colour, soft- 
 ness, and structure. I cannot coincide in this opinion, for it appears to me that the cranial and carotid branch, 
 es of the vidian are analogous in every respect. 
 
 t Arnold, who regards this opinion of Hippolyte Cloquet, which is adopted by Hirsel, as erroneous, states 
 that, at the junction of the cranial branch of the vidian with the facial nerve, there is a gangliform swelling, 
 in which he finds some analogy to the inter- vertebral ganglia, and which he considers to be a transition be- 
 tween a gangliform stalk and a true ganglion. 
 
 According to Arnold, the superficial or cranial branch, and the deep or carotid branch of the vidian, do not 
 come from a common trunk, but are merely juxtaposed, and are distinct throughout their entire extent. The 
 carotid branch is soft and reddish, presents all the characteristics of the ganglionic nerves, and is intended to 
 establish a communication between the superior cervical and the spheno-palatine ganglion. The cranial or sui 
 perficial petrosal branch, on the contrary, presents all the characters of the cerebro-spinal nerves ; it i«of t 
 white colour and firm consistence. 
 
 5N 
 
834 NEUROLOGY. 
 
 of the malar eminence of the superior maxillary bone, and anastomoses on a level with 
 the canine fossa with a filament from the anterior dental nerve. 
 
 The posterior and, inferior dental nerve, which is larger than the preceding, runs in a 
 curved direction below the malar eminence, the concavity of the curve being directed 
 upward, and anastomoses with the posterior and superior dental nerve, on a level with 
 the canine fossa. No filament is given off from the upper side of these nerves, but they 
 give off a great number of filaments downward, which anastomose, and form a series of 
 very remarkable meshes or areolae ; these meshes, and the 'dental nerve which come 
 from them, are situated within the substance of the bone, but are much nearer to the 
 sinus than to the outer surface of the bone. It is from these meshes that the extremely 
 delicate filaments arise which form the dental nerves of the molars and bicuspids ; their 
 number corresponds to that of the fangs of these teeth.* 
 
 Some filaments evidently terminate in the substance of the superior maxillary bone ; 
 no other bone in the body has so large a number of proper filaments. 
 
 The Anterior Dental Nerve. 
 
 The anterior dental or alveolo-dental nerve {j,fig. 298) is the only branch given off by 
 the superior maxillary nerve while within the infra-orbital canal ;t it arises about five or 
 six lines from the anterior orifice of that passage. It is so large that it may be regarded 
 as resulting from the bifurcation of the infra-orbital nerve. It soon enters a special ca- 
 nal formed for it in the superior maxillary bone, gives off on the outer side a small 
 branch which anastomoses with the posterior and superior dental nerve, passes at first 
 horizontally inward, and then vertically downward, turning round the margin of the an- 
 terior opening of the corresponding nasal fossa, and is reflected upon the floor of that 
 fossa ; during the whole of this course, it is situated within the substance of the superior 
 maxillary bone ; its horizontal portion is superficial, and its vertical portion is deep- 
 seated, having merely a thin bony lamella between it and the pituitary membrane. 
 Having arrived on a level with the floor of the nasal fossa, about two lines from its an- 
 terior opening, it expands into a great number of ascending and descending filaments ; the 
 aseending filaments are reflected upward within the anterior nasal spine, where they ter- 
 minate. They appear to me to send off a small ramification to the pituitary membrane. 
 The descending filaments terminate by supplying the dental nerves for the incisor, canine, 
 and first bicuspid teeth. A great number of filaments are also lost in the substance of 
 the bone. 
 
 I have never seen any filaments from the dental nerves entering the membrane of the 
 maxillary sinus. 
 
 The Terminal Branches of the Superior Maxillary Nerve. 
 
 Having reached the anterior orifice of the infra-orbital canal, the superior maxillary 
 nerve, the component bundles of which had been merely in juxtaposition, immediately 
 expands {i,fig. 301) into a pencil of diverging filaments beneath the levator labii supe- 
 rioris. These filaments {i,fig- 285) may be divided into ascending or palpebral, which 
 pass upward and outward beneath the orbicularis palpebrarum, and are distributed to the 
 skin and conjunctiva of the lower eyelid ; a great number of internal or nasal filaments, 
 which run upon the side of the nose, and are distributed to the skin of that organ ; one 
 of them runs along beneath the septum ; and, lastly, into descending or labial filaments, 
 which are the most numerous, and which enter the substance of the upper lip, and are 
 distributed to the skin and the mucous membrane : all these filaments, and especially the 
 labial, interlace and anastomose with the facial nerve, so as to form a plexus, named the 
 infra-orbital, to which we shall return in describing the facial nerve. 
 
 I have seen the nasal and the palpebral filaments arise together from the superior max- 
 illary nerve, before it had given off the anterior dental, enter a special canal situated on 
 the inner side of the infra-orbital canal, emerge opposite the line of demarcation between 
 the cheek and the nose, and then expand into their nasal and palpebral divisions ; while 
 the labial filaments had their usual arrangement. 
 
 The Inferior Maxillary Division of the Fifth J^erve. 
 Dissection. — As this nerve must be examined both upon its internal and its external 
 aspect, it must be dissected in both directions. An antero-posterior section of the head 
 in the median line will enable us to see, on the internal surface of the nerve, the chorda 
 tympani, the otic ganglion, and the origins of all the other branches which come from 
 the inner side of the inferior maxillary nerve, viz., the nerve of the internal pterygoid, 
 the lingual nerve, and the dental nerve. In order to see the distribution of the deep 
 temporal, the masseteric, the buccal, the internal pterygoid, and the auriculo-temporal 
 nerves, the inferior maxillary nerve must be exposed from its outer side, by breaking 
 down the zygomatic arch, reflecting down the masseter, which is to be detached as far 
 
 * In those molar teeth which have two or three roots, the nervous filaments snbdiii'ide and anastomose with 
 each other in the substance of the dental pulp. 
 
 t Sometimes, however, I have seen the posterior and superior dental nerve arise within the infra-orbital 
 'lanal. 
 
THE DEEP TEMPORAL NERVE, ETC. 835 
 
 back as the sigmoid notch, by sawing through the base of the coronoid process, and 
 turning the temporal muscle upward, and then by carefully dividing the external ptery- 
 goid muscle, through which the buccal nerve passes. 
 
 The inferior maxillary nerve (c, figs. 296, &c.), the most posterior and the largest di- 
 vision of the fifth nerve, passes outward and a little forward, and, after a very short 
 course within the cranium, escapes through the foramen ovale into the zygomatic fossa, 
 where it divides successively into seven branches. The non-ganglionic root (i, fig. 299) 
 of the fifth nerve is connected exclusively with the inferior maxUlary division (c) of its 
 other root, beneath which it lies, from which it can be distinguished by not having a 
 plexiform structure, with which it is not blended until it emerges from the foramen ovale. 
 Of the seven branches of the inferior maxillary nerve, three are external, namely, the an- 
 terior and posterior deep temporal, the masseteric, and the buccal ; one is posterior, name- 
 ly, the auriculo-temporal ; one is internal, the internal pterygoid ; and two are inferior, the 
 lingual or gustatory, and the inferior dental. These nerves may also be divided into col- 
 lateral branches, including the first five, and the terminal branches, namely, the lingual and 
 the inferior dental ; the otic ganglion, described by Arnold, is connected vidth this nerve.* 
 
 The Collateral Branches of the Inferior Maxillary Nerve. 
 
 The Deep Temporal Nerve. 
 
 The first external branch, or the deep temporal -nerve, arises from the outer side of the 
 inferior maxillary nerve, passes horizontally outward and forward between the roof of the 
 zygomatic fossa, with which it is in contact, and the eternal pterygoid muscle. Having 
 arrived at the ridge which separates the temporal from the zygomatic fossa, it anasto- 
 moses with several temporal branches derived from the buccal and masseteric nerves, 
 and forms a sort of plexus with them. The branches which emerge from this plexus 
 ascend vertically in the deep layers of the temporal muscle, in which most of them ter- 
 minate. 
 
 Some twigs anastomose with the temporal filaments derived from the lachrymal branch 
 of the ophthalmic nerve, and from the orbital branch of the superior maxillary nerve. t 
 One and sometimes two filaments perforate the temporal fascia, about a finger's breadth 
 above the zygomatic arch, and then ascend beneath the skin, to anastomose with the 
 auriculo-temporal and the facial nerves.t 
 
 The Masseteric Nerve. 
 
 The second external branch, or the masseteric nerve, arises from the same point as the 
 last nerve, and greatly exceeds it in size ; it comes off at an acute angle, passes horizon- 
 tally backward and outward in contact with the roof of the zygomatic fossa, between it 
 and the external pterygoid muscle ; it is then reflected downward over the upper part of 
 that muscle to gain the sigmoid notch of the lower jaw, upon which it is again reflected, 
 and then descends vertically, between the rcimus of the jaw and the masseter, or, rather, 
 in the substance of the deep layers of that muscle, down to the insertion of which it may 
 be traced. During its course along the upper wall of the zygomatic fossa, the masse- 
 teric nerve gives off a small, deep temporal branch, which runs along the periosteum, 
 passes into the temporal fossa, and sends off an articular branch to the temporo-max- 
 illary articulation. 
 
 The Buccal or Bucco-lahial Nerve. 
 
 The third external branch {g, fig. 300), the buccal, or, rather, the bucco-lahial nerve 
 (Chauss.), is very remarkable on account of its size and the extent of its distribution, 
 which gives it some resemblance to the corresponding portion of the facial nerve. It 
 arises from the outer side of the inferior maxillary nerve, by one, two, and sometimes 
 three roots, which perforate the external pterygoid, and join together as they emerge from 
 that muscle ; from thence it runs downward between the coronoid process of the lower 
 jaw and the tuberosity of the upper jaw, gives several twigs to the external pterygoid 
 muscle, and also some branches to the temporal muscle, of which one ascends and an- 
 astomoses with the deep temporal nerve, whUe another descends and is distributed to 
 the same muscle, near its insertion into the coronoid process ; the buccal nerve itself 
 sometimes perforates the lowest part of the insertion of the temporal muscle, and having 
 reached the back part of the buccinator, it expands into a great number of diverging 
 branches, like the facial nerve. 
 
 The ascending branches are distributed to the skin of the malar and buccal regions j 
 one of them forms an anastomic arch with the facial nerve behind the duct of Steno. 
 This anastomosis is very remarkable. The middle branches pass horizontally forward 
 on a level with the commissure of the lips, and terminate in the skin ; several of them 
 form a sort of plexus around the inferior coronary artery of the lip. The lowest of the 
 descending branches pass vertically downward, and even a little backward, upon the outer 
 surface of the buccinator, also beneath the deep surface and upon the outei" surface of 
 
 * We sometimes find a communicating filament between the superior and inferior maxillary nerves imme- 
 diately before they enter their respective foramina. 
 + [There is hence a communication between the branches of the three divisions of the fifth nerve.] 
 i [This cutaneous filament is one of the temporal filaments of the orbital branch of the superior maxillary 
 Qerve. — lEllis's VemonstraUons ; see note, p. 8.31.)] 
 
«36 
 
 NEUROLOGY. 
 
 the triangularis oris, and are entirely lost either in the skin or in the mucous membrane 
 It is doubtful whether the buccal nerve partially terminates in the orbicularis oris, the 
 triangularis oris, and the zygomaticus major. AH the filaments which enter these mus- 
 cles, and which appear at first sight to terminate in their substance, pass through them 
 to supply the mucous membrane ; their branches anastomose with the mental nerve be- 
 neath the triangularis oris ; several filaments are lost in the buccinator. 
 
 The Internal Pterygoid Nerve. 
 The internal collateral branch (<, fig- 299), or nerve for the internal pterygoid muscle, 
 which is very slender, comes off from the inner side of the inferior maxillary nerve in 
 contact with a grayish body, named the otic ganglion, runs downward and inward along 
 the inner surface of the internal pterygoid muscle, and ramifies in it. 
 
 The Auricula-temporal Nerve. 
 
 The posterior collateral branch, or the auricula-temporal nerve (the auricular or superfi- 
 cial temporal nerve of authors), is very large, flattened, and plexiform at its origin (be- 
 hind c, fig. 298 ; r, fig. 299) ; it sometimes arises by a great number of distinct roots ; it 
 passes backward and a little downward behind the neck of the condyle of the lower jaw, 
 and divides into two branches, a superior or ascending, and an inferior or descending branch. 
 
 The superior or ascending branch, the superficial temporal nerve, turns round the back 
 of the neck of the condyle, and ascends vertically between the articulation and the ex- 
 ternal auditory meatus ; having become sub-cutaneous, it divides into several filaments 
 (r, fig 285), which may be traced up to the highest part of the temporal fassa. 
 
 During its course this nerve gives off a very remarkable anastomotic branch, which 
 arises behind the neck of the condyle, and is reflected upon it so as to run forward be- 
 neath the facial nerve, with which it is blended opposite to the posterior border of the 
 masseter. This anastomotic branch is sometimes double. It may be regarded as one 
 of the origins of the facial nerve, which increases considerably in size after having re- 
 ceived it. 
 
 This branch is one of the principal communications between the facial nerve and the 
 fifth nerve, and modern physiologists have justly attached great importance to it. 
 
 The ascending branch also gives off some plexiform branches to the temporo-max- 
 illary articulation, and several filaments to the auditory meatus and the auricle. In the 
 temporal region it anastomoses with a very small filament, which is derived from the 
 deep temporal nerve, and which perforates the temporal fascia.* 
 
 It accompanies the temporal artery, for which it forms a sort of plexus, and then di- 
 vides into cutaneous filaments, which reach the crown of the head. 
 
 The inferior, descending, or auricular branch is as large as the preceding ; it forms a 
 plexus around the internal maxillary artery, behind the condyle, and sometimes presents 
 small ganglia ; it divides into several branches, some of which pass through the parotid 
 gland and are distributed to the lobe of the ear, while the others anastomose with some 
 filaments of the auricularis magnus nerve derived from the cervical plexus. One of 
 these branches joins the dental nerve, before that nerve enters the dental canal ; an- 
 other branch terminates in the temporo- maxillary articulation. 
 
 The Terminal Branches of the Inferior Maxillary Nerve. 
 The Lingual Nerve. 
 The lingual or gustatory nerve {n,figs. 298, 300; n n',fig. 301) passes downward and 
 Fig. 300. forward : it is at first situated between the exter- 
 
 nal pterygoid muscle and the pharynx, but it soon 
 passes between the two pterygoids {fig. 300), then 
 between the internal pterygoid and the ramus of 
 the lower jaw {fig. 298), and then runs forward 
 along the upper border of the sub-maxillary gland, 
 between it and the buccal mucous membrane, and 
 above the mylo-hyoid muscle ; it then passes be- 
 neath the sub-lingual gland, which it crosses, to 
 pass to its inner side, and, accompanied by the 
 Warthonian duct, which lies to its inner side and 
 crosses it at a very acute angle, it gains the corre- 
 sponding border of the tongue, and ramifies in the 
 substance of that organ. 
 
 During its passage between the two pterygoids 
 the lingual nerve is joined by that branch of the fa- 
 cial nerve which is known as the chorda tympani {x, 
 fig. 298), and which unites to it behind, forming a 
 very acute angle opening upward ; this branch of the 
 facial, which may be regarded as one of the roots 
 
 * tThis perforating cutaneous fUament is one of the temporal filaments of the orbital branch of the superior 
 maxillary nerve (see notes, p. 831, 835J.1 
 
THE INFERIOR DENTAL NERVE, ETC. 837 
 
 of the lingual, remains in contact with that nerve for some time, and is at last blended 
 with it. 
 
 The lingual nerve also receives, sometimes before, and sometimes after being joined 
 by the chorda tympani, a very considerable anastomotic branch from the inferior dental : 
 this branch is rarely wanting. 
 
 After receiving these two branches, the lingual nerve becomes considerably increased 
 in size, and during its course gives off several filaments to the tonsils, the mucous mem- 
 brane of the cheeks and the gums. 
 
 Opposite the sub-maxillary gland, the lingual nerve presents a very remarkable gan- 
 glion, generally described as the sub-maxillary ganglion {aitVLdtei behind X, fig. 300); the 
 trunk of the nerve does not enter into its formation, but it appears to be formed only by 
 its inferior filaments. It has been gratuitously supposed that this ganglion is formed 
 exclusively by the chorda tympani, which, according to such a view, after running in 
 mere contact with the lingual nerve, becomes detached from it (opposite n) to enter the 
 ganglion (x) : we have stated that there was equally little reason to suppose that the 
 chorda tympani was the continuation of the cranial branch of the vidian. The sub-max- 
 illary ganglion, the size of which is very variable, gives off a great number of filaments, 
 most of which are distributed to the sub-maxillary gland ; one of these filaments accom- 
 panies the Warthonian duct. 
 
 Having reached the sub-lingual gland, the lingual nerve supplies that gland with a 
 great number of filaments, which dip into it and form a plexus of very delicate meshes. 
 
 In the tongue, the lingual nerve is situated at the lateral border of that organ, and on 
 a plane above that of the hypoglossal nerve, with which it communicates by an anasto- 
 motic branch, forming a loop. It becomes gradually diminished in size by giving off a 
 very numerous series of filaments {n',fig. 301), which turn round the border of the tongue, 
 pass forward and upward, perforate the muscles of that organ, and spread out into pen- 
 cils, the filaments of which may be traced into the papillae of the mucous membrane. 
 The nerve, reduced to a single filament, terminates at the point of the tongue 
 
 The Inferior Dental Nerve. 
 
 The inferior dental nerve {m,fig. 298), larger* than the lingual, descends with it, at first 
 between the two pterygoid muscles, and then between the internal pterygoid and the ra- 
 mus of the lower jaw : in this situation it is kept in contact with the bone by a layer of 
 fibrous tissue, which is improperly called the internal ligament of the temporo-maxillary 
 articulation, and which separates the nerve from the lingual nerve and the internal pter- 
 ygoid muscle ; it soon enters the dental canal, which it traverses (m) throughout its 
 entire extent, accompanied by the inferior dental artery, and protected by a fibrous ca- 
 nal ; during its course it supplies the molar and the bicuspid teeth, giving a twig to each 
 prong, and having reached the mental foramen, divides into a mental and an incisor branch. 
 
 The Myloid Branch. — As it enters the inferior dental canal, the nerve gives off a small 
 branch, the myloid branch {z, fig. 300), which arises from its posterior border, opposite 
 the corresponding artery, is received into a furrow upon the inner surface of the ramus 
 of the jaw, against which it is retained by a layer of fibrous tissue, and then, emerging 
 from this furrow, passes upon the upper surface of the mylo-hyoid muscle, in which it 
 ramifies. A great number of filaments from the myloid nerve enter the anterior belly of 
 the digastric muscle. t 
 
 The mental branch {t,fig. 285), the continuation of the inferior dental nerve, as far as 
 size is concerned, passes through the mental foramen, and expands into diverging fila- 
 ments, which are distributed, in reference to the lower lip, in the same way as the infra- 
 orbital branch is to the upper lip. These filaments interlace with the facial nerve, and 
 form with it a sort of mental plexus ; they are intended for the skin and the mucous 
 membrane of the lower lip : most of them pass to the free border of that lip. 
 
 The inrisor dental branch, which is extremely small, continues in the original course 
 of the inferior dental nerve, and subdivides to supply the canine and two corresponding 
 incisor teeth. 
 
 The inferior dental nerve represents in the lower jaw the infra-orbital portion of the 
 superior maxillary nerve in the upper jaw. 
 
 The Otic Ganglion. 
 
 I cannot terminate the description of the inferior maxillary nerve without noticing a 
 ganglion recently described by Arnold, under the name of the olic ganglion, which he 
 compares to the ophthalmic ganglion, and which has served him as the basis of an inge- 
 nious theory respecting the nerves of the head. The following is the position of the 
 ganglion, as indicated by Arnold : "The otic ganglion is situated (behind I, fig. 299) im- 
 mediately below the foramen ovale, on the inner side of the third or inferior maxillary 
 
 * I have observed that thi.s nerve was much smaller in old than in young- subjects. 
 
 t [Filaments are also given to the sub-maxillary gland ; according to Ellis, some branches pass through 
 the mylo-hyoid muscle and enter the genio-hyoid ; and it is stated bv Alcock that a branch reaches the de- 
 pzecsor labii inferioris.] 
 
888 NEUROLOGY. 
 
 division (c) of the fifth nerve, a little above the origin of the superficial temporal or au- 
 ricular nerve (auriculo-temporal), at the spot where the inferior maxillary nerve gives off 
 from its external surface the deep temporal and buccal nerves, and where the small root 
 of the fifth unites intimately with the large root. On the inner side, this ganglion is 
 covered by the cartilaginous portion of the Eustachian tube, and by the origin of the ex- 
 ternal peristaphyline {circumflexus palati) muscle ; behind, it is in contact with the mid- 
 dle meningeal artery. Its external surface rests upon the inner side of the inferior max- 
 illary nerve." 
 
 There can be no doubt that in the situation indicated by Arnold, there is a thin and 
 not very well-defined layer of reddish, pulpy tissue, placed upon the inner side of the in- 
 ternal pterygoid nerve, and which presents the chief characters of ganglionic tissue ; for 
 it is traversed by nervous filaments, which proceed from it as from a centre, and run in 
 various directions. 
 
 Its connexions with the inferior maxillary nerve are effected by its direct adhesion to 
 that nerve, which adhesion, according to Arnold, takes place by means of several very 
 short, nervous filaments {short root), which appear to come from the small root of the fifth 
 pair, and also by its adhesion to the internal pterygoid nerve ; so that, at first sight, the 
 ganglion would appear to originate from that nerve, or the nerve from the ganglion. 
 
 The otic ganglion is also connected with the glosso-pharyngeal by means of a filament, 
 which Arnold describes under the name of the small superficial petrosal nerve, to distin- 
 guish it from the great superficial petrosal, or cranial branch of the vidian. This fila- 
 ment, which proceeds from the nerve of Jacobson, or tympanic branch of the glosso-pha- 
 ryngeal, is compared by Arnold to the Imig root of the ophthalmic ganglion : it passes 
 out of the cavity of the tympanum by a special canal, in front of the hiatus Fallopii, runs 
 forward and outward (from 7 towards c, fig. 296), emerges from the cranium through a 
 special foramen, between the petrous portion of the temporal bone and the spinous pro- 
 cess of the sphenoid, and proceeds (above I, Jig. 300) to enter the otic ganglion.* Ar- 
 nold admits a third root for the otic ganglion, namely, a soft root, which he traces from 
 the nervous plexus that surrounds the middle meningeal artery, and is derived from the 
 great sympathetic. 
 
 The preceding filaments may be regarded as the filaments of origin of the otic gan- 
 glion.t 
 
 The Branches which proceed from the Otic Ganglion. — The principal filament from the 
 otic ganglion runs backward and upward towards the canal which contains the internal 
 muscle of the malleus, and is lost in that muscle. This twig must be carefully distin- 
 guished from the small superficial petrosal nerve, which is placed above it. Some other 
 filaments join the auriculo-temporal nerve, which generally arises by two roots. 
 
 Lastly, the otic ganglion sends off a twig to the circumflexus palati muscle. 
 
 The Sixth Pair, or External Motor Nerves of the Eyes. 
 
 The very simple distribution of the external motor nerve of the eye, or sixth crania} 
 nerve, contrasts strongly with that of the fifth nerve ; it arises from the furrow between 
 the pons Varolii and the medulla oblongata, immediately forms two fasciculi or roots, a 
 large and a small, which unite in the cavernous sinus ; they pass vertically upward, per- 
 forate the dura mater {b, fig. 296) at the side of the basilar groove by one or two open- 
 ings, to the inner side of and below the fifth nerve, gain the apex of the petrous portion 
 of the temporal bone, over which they turn, and then pass horizontally forward to enter 
 the cavernous sinus. During the course of the nerve through that sinus, it rests upon 
 its lower wall, crosses (above 6, fig. 301) on the outer side of the vertical portion of the 
 internal carotid artery, around which it turns, and then runs along its horizontal portion. 
 The sixth nerve forms a most important anastomosis, on account of which it was for a 
 long time regarded as the origin of the great sympathetic. As it crosses the internal 
 carotid in the cavernous sinus, it communicates by one or two filaments with the supe- 
 rior cervical ganglion. It also communicates, at the same point, with the ophthalmic 
 division of the fifth nerve. 
 
 Lastly, it enters the orbit through the widest part of the sphenoidal fissure, passes 
 through the fibrous ring which is common to it and to the inferior division of the com- 
 mon motor nerve, crosses, at an acute angle, beneath the ophthalmic nerve, and gains 
 the inner surface of the external rectus, and penetrates that muscle, after having ex- 
 panded into a pencil of very delicate filaments. 
 
 We shall again advert to the communication between this nerve and the superior cer-'» 
 vical ganglion. 
 
 * This small superficial petrosal nerve is very distinct from the great superficial petrosal nerve, being situ 
 ated in front of and parallel to that nerve. In a subject which I dissected in J826, I found this small nerve 
 presenting the following peculiarity : it had a well-marked nodule or ganglion, which gave off a filament to 
 the middle meningeal artery, and some small twigs, which appeared to me to be lost in the substance of the 
 sphenoid bone ; but I did not discover the connexions of this nerve. 
 
 t Arnold admits an indirect communication between the otic gan!>;lion and the acoustic nerve through the 
 intervention of the facial nerve. The existence of this communication appears to me very doubtful, as well 
 as the communication of the otic ganglion with the great sympathetic, by means of the twigs on the middle 
 meningeal artery 
 
THE FACIAL NERVE. 839 
 
 The Seventh Pair of Nerves 
 The Portio Dura, or the Facial JVerve. 
 
 We have already traced the facial nerve, or the portio dura of the seventh, from its on 
 gin to the internal auditory meatus, which it enters together with the auditory nerve (7, 
 Jig. 296), which nerve lies below and behind the facial, and forms a groove for its recep- 
 tion. Having reached the bottom of the internal auditory meatus, this nerve follows the 
 long course of the facial canal,* or aqueduct of Fallopius, a winding passage which is 
 formed in the petrous portion of the temporal bone, and which opens by one end into the 
 internal auditory meatus, and, by the other, upon the lower surface of the pars petrosa 
 at the stylo-mastoid foramen. 
 
 The facial nerve traverses this canal, which is exclusively appropriated to it ; it is at 
 first directed outward (n, fig. 296), and, after proceeding for about a line, bends sudden- 
 ly, and runs backward, in the substance of the internal wall of the cavity of the tympa- 
 num, above the fenestra ovalis. Having reached the back of the tympanum, it forms 
 another bend, and passes vertically downward (o, figs. 298, 300) to the stylo-mastoid fo- 
 ramen. It follows, therefore, that the facial nerve describes two curves, like the aque- 
 duct of Fallopius, and is horizontal in its first two portions and vertical in the third. 
 
 On emerging from the stylo-mastoid foramen, the facial nerve runs forward in the 
 substance of the parotid gland, and, after a course of about five or six hues, divides into 
 two terminal branches, the temporo-facial (g, fig. 285) and the cervico-facial (/), which 
 expand into a great number of diverging filaments, and cover the temples, the whole of 
 the face, and the upper part of the neck, with their radiations and anastomoses. 
 
 The facial nerve gives off and receives certain collateral branches before and others 
 after its exit from the stylo-mastoid foramen. 
 
 The Collateral Branches of the Facial Nerve, before its Exit from the Stylo-mastoid Foramen. 
 
 In the internal auditory meatus the facial nerve receives some twigs from the auditory, 
 a remarkable anastomosis, which deserves the attention of physiologists. 
 
 Opposite to the hiatus Fallopii, i. e., at the first bend formed by the Fallopian aque- 
 duct, the facial nerve is joined by the cranial branch of the vidian, or the great super- 
 ficial petrosal nerve (c> figs. 296, 300). According to MM. Ribes, Hippolyte Cloquet, 
 and Hirzel, this branch is applied to the facial nerve, but does not anastomose with it, 
 and is detached from it lower down to constitute the chorda tympani nerve ; and as the 
 cranial branch of the vidian arises from the spheno-palatine ganglion, and the chorda 
 tympani is supposed to enter the sub-maxillary ganglion, it is seen that, according to 
 this view, the cranial branch of the vidian and the chorda tympani, which is regarded 
 as its prolongation, would establish a communication between the spheno-palatine and 
 sub-maxillary ganglia. It is by no means proved, however, that the chorda tympani en- 
 ters the sub-maxiUary ganglion ; and, again, the supposed connexion between the cra- 
 nial branch of the vidian and the chorda tympani is opposed to facts. The cranial 
 branch of the vidian and the facial nerves, indeed, are not in mere juxtaposition, but 
 anastomose and are blended with each other, and the chorda tympani has no sort of re- 
 lation to the former of these nerves. This independence of the branch of the vidian 
 nerve and the chorda tympani can be most clearly seen when the parts have been ma- 
 cerated in diluted nitric acid.t 
 
 If an explanation must be given of this remarkable anastomosis between the vidian 
 and facial nerves, I would say that the cranial branch of the vidian may be regarded as 
 a remote origin or a re-enforcing branch of the facial nerve. 
 
 The facial nerve, according to Soemmering and those who have followed him, gives 
 off a twig to the internal muscle of the malleus, and another to the small muscle of the 
 stapes ; but, in the first place, the existence of a stapedius muscle is doubtful, and, con- 
 sequently, the existence of a corresponding nervous twig must also be so, and, in the 
 second place, the internal muscle of the malleus is not supplied from the facial nerve, 
 but from the inferior maxillary division of the fifth nerve, and more especially from that 
 pulpy, reddish tissue, named by Arnold the otic ganglion. 
 
 Before leaving the aqueduct of Fallopius, the facial nerve (n,fig. 296) gives a remark- 
 able filament, named the chorda tympa7ii, which pursues a recurrent course (y) from be- 
 low upward in a peculiar canal, parallel to the aqueduct of Fallopius, enters the cavity 
 of the tympanum through an opening to the inner side of and behind the attachment of 
 the membrana tympani, passes downward and forward through the cavity of the tym- 
 
 * For what purpose is this long- course within the petrous portion of the temporal bone ? Those physiolo- 
 gists who believe the facial nerve to be of a mixed nature, that is, both sensory and motor, have laid great 
 stress upon this point, which they conceive to be favourable to their views ; but there is not the slightest 
 shadow of a proof that the facial nene possesses these two properties. 
 
 t Arnold has pointed out, at the junction of the cranial branch of the vidian with the facial nerve, a gangli- 
 form swelling, which he regards as a transition between a gangliform enlargement and a true ganglion ; from 
 this swelling, which he compares to the ganglia of the posterior roots of the spinal nerves, he says a filament 
 is given off to anastomose with the auditory nerve at the bottom of the internal .auditory meatus. I have not 
 been fortunate enough to discover this filament ; nor have I ever seen any gangliform appearance at the junc- 
 tion of the vidian and facial nerves. 
 
840 NEUKOLOGY. 
 
 panum, between the handle of the malleus and the vertical ramus of the incus, and 
 emerging from that cavity {x,fig. 298), not through the Glasserian fissure, but through a 
 special opening already described (see Organ of Hearing — Cavity of the Tympanum), is 
 applied to the lingual nerve («), of which it may be regarded as a late origin, or re-enfor- 
 cing branch. 
 
 The facial branch also receives, in the aqueduct of Fallopius, opposite to where it gives 
 off the chorda tympani, a very remarkable branch from the pneumogastric nerve, which 
 Arnold has named the auricular branch of the pneumogastric. 
 
 The Collateral Branches of the Facial Nerve, after its Exit from the Stylo-mastoid Foramen. 
 
 Before its terminal division, the facial nerve gives off two branches, the posterior 
 auricular and the styloid. I have never seen any parotid branch, properly so called. 
 
 The posterior auricular, which would be better named the auriculo-occipital, comes ofl 
 from the nerve within the stylo-mastoid foramen, and is immediately applied against the 
 mastoid process, turning round over its anterior and then its outer surface ;* as it lies in 
 front of the mastoid process, it anastomoses with a remarkable twig from the deep auric- 
 ular branch of the auricularis magnus from the cervical plexus ;t after this, it divides 
 into two branches : an ascending or auricular branch {m, fig. 299), properly so called, 
 which, having first supplied, then perforates the posterior auricular muscle, turns round 
 the auricle, and terminates in the superior auricular muscle ; and a horizontal or occipital 
 branch («, fig. 285), which is larger, and forms the continuation of the nerve ; it passes 
 immediately beneath the posterior auricular muscle, to which it gives some filaments, 
 then runs exactly along the superior semicircular line of the occipital bone, and termi- 
 nates by giving off from its upper side a series of small filaments, which are lost in the 
 occipital portion of the occipito-frontalis : they can be traced as far as the median line, 
 but none of them are distributed to the skin. 
 
 The styloid branch arises from the back of the facial nerve, at its exit from the stylo- 
 mastoid foramen, and enters the stylo-hyoid muscle, after having run along its upper 
 border. 
 
 The posterior mastoid or digastric branch often arises by a common trunk with the pre- 
 ceding, enters the posterior belly of the digastric muscle, and sends off an anastomotic 
 twig to the glosso-pharyngeal nerve. 
 
 The Terminal Branches of the Facial Nerve. 
 
 The Temporo-facial Nerve. 
 
 The temporo-facial nerve {g, fig. 285) passes upward and forward in the substance of 
 the parotid, forming, with the trunk of the facial nerve, an arch having its concavity 
 turned upward ; it crosses the neck of the condyle of the lower jaw, and receives in this 
 situation, by its deep surface, one, or sometimes two branches from the auriculo-tempo- 
 ral nerve, a branch of the inferior maxillary. This anastomotic branch establishes a 
 very important connexion between the fifth and facial nerves. 
 
 The temporo-facial nerve, which is flattened and plexiform where it is joined by the 
 branch from the fifth, afterward expands into a number of filaments, which anastomose 
 with each other, so as to form arches, from the convexity of which a number of diverging 
 filaments of unequal size proceed like rays, and cover the whole space comprised be- 
 tween a vertical line drawn in front of the ear, and a horizontal line corresponding to the 
 base of the nose. 
 
 All these branches, which anastomose several times with each other, and form a suc- 
 cession of arches somewhat resembling those of the mesenteric arteries, may be divided 
 into the temporal, the orbital, and the infra-orbital or buccal branches. 
 
 The temporal branches ascend, cross over the zygomatic arch at right angles, and cov- 
 er with their ramifications the whole of the temporal and frontal regions, anastomosing 
 with filaments from the frontal branch of the first [from the orbital branch of the second], 
 and from the auriculo-temporal branch of the third division of the fifth nerve. 
 
 All these branches lie between the skin and the temporal aponeuroses ; some of them 
 supply the skin, but* the majority are distributed to the frontal portion of the occipito- 
 frontalis muscle, below which they are situated, and may be traced as far as the median 
 line. 
 
 The orbital branches may be divided into the superior palpebral, which are remarkably 
 long, and pass beneath the orbicularis palpebrarum, to ramify in that muscle and the 
 corrugator supercilii. Several of these anastomose with twigs from the supra-orbital 
 nerve : the middle palpebral branches. Which gain the outer angle of the eyelids, and are 
 distributed between the upper and lower eyelids, and the superior palpebral branches, 
 which are generally named the malar branches ; they pass horizontally forward, opposite 
 to the lower part of the orbicularis palpebrarum, and are reflected upward, to enter the 
 
 * This little nerve is lodged in the furrow between the mastoid and vaginal processes (see Osteology, 
 p. 43). 
 
 t [It is also joined, according to Arnold, by a filament from the auricular branch of the pneumogastric (sea 
 note, p. 844). 
 
THK CERVICO- FACIAL NERVE. 841 
 
 substance of the lower eyelid, between the palpebral aponeurosis and the palpebral por- 
 tion of the orbicularis, in which they terminate. 
 
 They may be traced as far as the free border of the tarsal cartilage, where they anas- 
 tomose with each other. 
 
 The infra-orbital or buccal branches of the temporo-facial are given off from one or two 
 large branches which accompany the Stenonian duct ; they expand into a great number 
 of filanients, which may be divided into a superficial and a deep set : the superficial branch- 
 es ran beneath the skin, and above the orbicularis oris, the two zygomatic, and the le- 
 vator labii superioris, all of which they supply ; there can be no doubt that they also 
 give cutaneous filaments ; these are very small, and very long, and may be followed as 
 far as the hair follicles in the upper lip ; some of these superficial branches reach the 
 lower eyelid, several accompany the facial and angular veins, anastomose with twigs 
 from the infra-trochlear branch of the nasal nerve, and ascend as far as the pyramidalis 
 nasi, in which they terminate. 
 
 The deep branches pass beneath the levator labii superioris, send off numerous fila- 
 ments to that and the levator anguli oris, and form, together with the terminal divisions 
 of the infra-orbital branch of the superior maxillary, a very remarkable plexus, which 
 may be called the infra-orbital. 
 
 This plexus is formed by the interlacement of the radiating branches of the facial 
 nerve with those of the infra-orbital branch of the superior maxillary division of the fifth 
 nerve. Now, as the facial nerve radiates from without inward, and the infra-orbital 
 from above downward, it follows that the branches of these two nerves meet each other 
 at right angles. This arrangement can be rendered more evident by pulling the two 
 sets of nerves in the direction of their length. Most of these branches interlace with- 
 out anastomosing, and proceed directly to their destination. The destination of the 
 facial nerve is evidently rather to the muscles than to the skin ; that of the infra-orbital 
 branch of the fifth nerve is rather to the skin and mucous membrane than to the mus- 
 cles ; nevertheless, it cannot be doubted that the facial nerve supplies some cutaneous 
 filaments, and that the fifth nerve gives some twigs to the muscles. Besides, there are 
 some undoubted anastomoses between these two nerves. The facial also communicates 
 very freely with the buccal nerve, a branch of the inferior maxillary. 
 
 The infra-orbital branches of the temporo-facial nerve supply the two zygomatics, the 
 levator labii superioris, the levator labii superioris alaeque nasi, the depressor alae nasi, 
 the transversalis nasi, the levator anguli oris, and the orbicularis oris. I would also 
 point out a very remarkable branch, which enters the substance of the ala of the nose, 
 and appears to be intended for that sort of sphincter muscle found in the cutaneous fold 
 of the alae. This branch anastomoses with the naso-lobar branch of the internal nasal 
 nerve. 
 
 The infra-orbital branches of the fifth nerve are distinguished from the infra-orbital 
 branches of the facial nerve, by their direction ; by being more deeply seated ; by being 
 much larger ; and by being arranged in successive layers, which are three in number : 
 a sub-cutaneous, a sub-mucous, and a muscular ; this last set perforates the orbicularis 
 oris, in which some filaments appear to terminate. Among the infra-orbital branches 
 of the fifth nerve, there is one which may be called the nerve of the sub-septum, which 
 runs on the side of the median line, as far as the tip of the nose, where it terminates. 
 Lastly, the infra-orbital branches of the fifth give a dorsal branch for the nose, and two 
 ascending palpebral branches, which can be easily distinguished from the palpebral 
 branches of the facial nerve. 
 
 The Ccrvico-facial Nerve. 
 
 The ccrvico-facial nerve (/, fig. 285), which is smaller than the temporo-facial, follows 
 the original course of the facial nerve, and, like it, runs downward and forward in the 
 parotid gland ; opposite to the angle of the lower jaw it divides into three or four branch- 
 es, which subdivide into secondary branches, which may be arranged into the buccal, men- 
 tal, and cervical sets. 
 
 The buccal branches run horizontally forward in front of the masseter, to which they 
 give off" some small filaments, and then anastomose with each other and with the infra- 
 orbital branches of the temporo-facial nerve. A very beautiful anastomosis is found be- 
 tween the buccal branch of the inferior maxillary and one of these buccal branches of 
 the cervico-facial nerve : we have already pointed out a similar anastomosis between 
 an infra-orbital branch of the temporo-facial and this same buccal branch of the inferior 
 maxillary. 
 
 The mental branches are intended for the lower lip. They are reflected upward, so as 
 to describe an arch having its concavity directed upward ; they are at first situated be- 
 neath the platysma myoides, then pass beneath the triangularis oris, and form, with the 
 mental branch of the inferior maxillary division of the fifth nerve, an interlacement or 
 mental plexus, which has a close analogy with the interlacement of the infra-orbital 
 branches of the facial with those of the superior maxillary division of the fifth nerve, but 
 is less comnlicated. 
 
 50 
 
842 NEUROLOGY. 
 
 Thus, the mental branches of the facial nerve are more superficial than those of the 
 fifth, and their filaments are smaller ; the radiating branches of the facial nerve run at 
 first forward and then upward, while those of the fifth nerve run directly upward. The 
 mental brandies of the facial nerve perforate the quadratus rnenti and the orbicularis 
 oris, to which muscles they are almost entirely distributed ; they also send several long 
 and slender filaments to the point of the chin, some of which are cutaneous. The men- 
 tal branches of the fifth nerve are chiefly situated between the muscles and the mucous 
 membrane, to w hich latter they are distributed, more especially to the free borders of 
 the lower lip. 
 
 The cervical branches of the cervico-facial run forward in the supra-hyoid region, be- 
 neath the platysma, and, describing arches with their concavities turned upward, they 
 pass upward and forward to terminate near the chin. Among these branches, there is 
 one which passes vertically downward to anastomose with the superficial cervical nerve 
 of the cervical plexus. 
 
 The cervical branches of the facial nerve are separated from the cervical branches of 
 the cervical plexus by the platysma, and they are all distributed to that muscle and the 
 levator labii superioris. 
 
 Summary. — The facial nerve supplies all the cutaneous muscles of the cranium and 
 of the face, and, therefore, section and compression of this nerve cause complete paral- 
 ysis of these muscles : it is the nerve of expression, or the respiratory nerve of the 
 face {Bell) ; it also evidently gives off some cutaneous filaments, especially near the 
 commissure of the lips, and this may explain the numbness which I have known to oc- 
 cur in individuals affected with hemiplegia of the face ; lastly, it furnishes a great num- 
 ber of anastomotic filaments (whence it has been called the small sympathetic) ; these 
 are given to the branches of the cervical plexus, to the auditoiy nerve, to the pneumo- 
 gastric, and more especially to the fifth nerve. 
 
 The anastomoses of the facial with the fifth nerve merit special notice ; they are ef- 
 fected with the frontal and nasal nerves of the ophthalmic or first division of the fifth ; 
 with the superior maxillary or second division by means of the infra-orbital nerves and 
 the cranial branch of the vidian, which latter I even regard as one of the origins of the 
 facial nerve ; and with the inferior maxillary or third division of the fifth by means of 
 the mental nerve, the buccal nerve, and more especially the auriculo-temporal nerve. 
 The branch given by the auriculo-temporal to the facial nerve may be regarded as one 
 of the origins of the last-mentioned nerve. 
 
 Notwithstanding these numerous anastomoses, the facial nerve and the fifth nerve 
 cannot supply the place of each other. Anatomy shows no difference in the structure 
 of these nerves, but a great difference in their distribution ; the facial nerve being in- 
 tended for the muscles, while the fifth is distributed to the integuments and the organs 
 of the senses. 
 
 Function. — The facial is a nerve of motion. This fact may be deduced from its ana- 
 tomical description no less than from physiological experiments and the effects of disease. 
 
 The Portio Mollis, or the Auditory J^erve. 
 
 The auditory nerve (7, figs. 296, 301), which we have already traced as far as the in- 
 ternal auditory meatus, enters that canal with the facial nerve, for which it forms a 
 groove, and divides into two cords, which remain distinct throughout the whole extent 
 of the passage, but continue in contact with each other, and at length pass through the 
 foramina in the cribriform plate already described as existing at the bottom of the meatus 
 (see Osteology). 
 
 In order to understand the farther distribution of the auditory nerve, the cribriform 
 plate of the auditory meatus must be examined with the same attention as was devoted 
 by Scarpa to the cribriform plate of the ethmoid, with which it has so many analogies. 
 As the cribriform plate of the ethmoid presents a particular fissure for the passage of the 
 ethmoidal branch of the ophthahnic nerve, so the cribriform plate of the internal auditory 
 meatus presents a special opening for the passage of the facial nerve ; and again, the 
 auditory, like the olfactory nerve, seems as if it were pressed through the foramina of 
 the cribriform plate to enter the internal ear. 
 
 Of the two terminal branches of the auditory nerve, the anterior is intended for the 
 cochlea, the posterior for the vestibule and semicircular canals. 
 
 The cochlear branch turns spirally, like that part of the bottom of the auditory meatus 
 to which it belongs, and which is called the tractus spiralis. It then turns upon itself, 
 as observed by Valsalva, and presents somewhat of a ganglionic appearance. From this 
 sort of enlargement the cochlear filaments proceed ; those which belong to the first turn 
 of the cochlea run along the surface of the modiolus ; the others enter the canals of the 
 modiolus, and are distributed on the second, and the succeeding half turn at the summit 
 of the cochlea. I have already described the very regular manner in which these fila- 
 ments spread upon the spiral septum, the subdivision of each of them into two or three 
 filaments, which anastomose with each other lite the ciliary nerves, and the gradual dim- 
 inution in the length of these filaments from the base to the apex of the cochlea ; so that, 
 
THE GLOSSO-PHARYNGEAL NERVE. 
 
 it we suppose the spiral septum spread out, it might be compared to a harpsichord, the 
 longest strings of which would be represented by the filaments at the base of the trian- 
 gle formed by the septum, and the shortest by those at its apex (see Internal Eae, p. 681). 
 
 The vestibular branch divides into three parts, the largest of which enters the utricle 
 and the ampullce of the superior vertical and horizontal membranous canals, the middle, 
 sized branch passes to the sacculus, and the smallest branch to the ampulla of the pos- 
 terior or inferior vertical semicircular canal. 
 
 Function. — The auditory nerve is exclusively the nerve of hearing. 
 
 The Eighth Pair op Nerves. 
 
 The First Portion, or Glosso-Pharyngeal JVerve. 
 
 Dissection. — Remove, by a triangular section, the posterior half of the border of the 
 
 foramen lacerum posterius ; carefully detach the jugular vein, in front of which the 
 
 nerves are situated, examine the connexions of the glosso-pharyngeal with the pneumo- 
 
 gastric and spinal accessory nerves. 
 
 The glosso-pharyngeal nerve {pharyngo-glossal), the anterior portion of the eighth nerve 
 (8, Jigs. 296, 301), the ninth nerve of some authors, is intended for the pharynx and the 
 tongue. 
 
 Having arisen from the restiform body, above and on a line with the pneumogastric,* 
 by a series of roots which are continuous with the roots of that nerve, the glosso-pharyn- 
 geal emerges from the foramen lacerum posterius through a fibrous canal which is prop- 
 er to it, and which is situated in front of the canal that is common to the pneumogastric 
 and spinal accessory nerves ; it is placed to the inner side of the internal jugular vein, 
 from which it is separated by a cartilaginous and sometimes osseous lamina. 
 
 During its passage through this canal it presents a ganglionic enlargement, which was 
 described by Andersh under the name of ganglion petrosum, and is now more generally 
 known as the ganglion of Andersh. 
 
 This ganglion is situated in a depression on the petrous portion of the temporal bone 
 {receptaculum ganglii petrosi) ; from it the nerve pro- Pig. 301. 
 
 ceeds as a rounded cord, which descends vertically 
 (I, fig. 301) behind the styloid muscle in front of the 
 internal carotid, then between the stylo-pharyngeus 
 and the stylo-glossus, and passing forward so as to 
 describe a curve with its concavity turned upward, 
 runs in front of the posterior pillar of the fauces and 
 behind the tonsil, and then passing beneath the hyo- 
 glossus muscle (2), ramifies, to enter the base of the 
 tongue and supply the mucous membrane. 
 
 During this course it gives off the nerve of Jacob- 
 son, and an anastomotic twig to the facial nerve ; it 
 communicates with the spinal accessory and the 
 pneumogastric ; it gives off a muscular branch to 
 the digastricus and stylo-pharyngeus, and it supplies 
 some carotid filaments, and some pharyngeal and 
 tonsillar branches. 
 
 The Nerve of Jacobson. — In order to facilitate the 
 study of the course of this nerve, I shall first de- 
 scribe the canals through which it passes : 
 
 Upon the ridge which separates the jugular fossa 
 from the carotid canal, to the outer side of the aqueduct of the cochlea, is found an open- 
 ing, which is the inferior orifice of the canal of Jacobson. This canal runs backward 
 and upward into the substance of the internal wall of the cavity of the tympanum, in 
 front of the fenestra rotunda ; there it branches into three canals : one descending, which 
 opens into the carotid canal ; and two ascending canals, an anterior, which runs forward 
 and upward, and opens into the groove for the great superficial petrosal or cranial branch 
 of the vidian nerve, and a posterior, which at first ascends vertically behind the fenestra 
 ovalis, then curves suddenly and becomes horizontal, and opens upon the upper surface 
 of the pars petrosa in a groove parallel to and on the outer side of the groove for the 
 cranial branch of the vidian nerve. 
 
 The nerve of Jacobson, which comes off from the petrosal ganglion, or ganglion of An- 
 dersh, enters this canal. In one subject I found it to consist of two filaments, one from 
 the pneumogastric, and the other from the glosso-pharyngeal. t 
 
 This nerve soon divides into three filaments corresponding to the three branches of the 
 
 * Several modern physiologists, believing the glosso-pharyngeal to be a mixed nerve, sensory in its lingual 
 portion, and motor in its pharyngeal, have, therefore, supposed it to have tviro distinct roots : a larger, which 
 is near the par vagum, and a smaller, v^hich lies near the facial nerve ; and, from analogy, they regard the 
 former as the sensory, and the latter as the motor root. 
 
 t In another subject it was formed by the anastomoses of a twig from the auricular branch of the pneumo- 
 gastric with a twig from the glosso-pharyngeal. 
 
844 ■.i''.i:.: il/ NEUROLOGY. 
 
 canal ; the descending filament joins the carotid plexus ; of the two ascending lilaments, 
 one anastomoses with the cranial branch of the vidian, or the great superficial petrosal 
 nerve {v, Jig. 300), while the other constitutes the small superficial petrosal nerve, which 
 reaches the upper surface of the pars petrosa in front of the preceding, and terminates 
 in the reddish tissue known as the otic ganglion.* 
 
 It follows, therefore, that the nerve of Jacobson connects the glosso-pharyngeal nerve 
 with the superior maxillary division of the fifth nerve (especially with the spheno-pal- 
 atine ganglion through the intervention of the vidian nerve), with the otic ganglion of 
 the inferior maxillary division, and with the superior cervical ganglion of the sympathetic. 
 
 The anastomotic branch to the facial nerve arises from the ganglion of Andersh imme- 
 diately below the nerve of Jacobson ; it runs downward and outward behind the styloid 
 process, is then reflected upward, so as to describe a loop with its concavity turned up- 
 ward, and anastomoses with the facial immediately after the exit of that nerve from the 
 stylo-mastoid foramen. This branch appears to me to be the remaining trace of a con- 
 siderable branch of the facial nerve, which I have seen partially supplying the place of 
 the glosso-pharyngeal (see the Tongue, p. 646). 
 
 The Anastomosis of the Glosso-pharyngeal with the Spinal Accessory and Pneumogastric 
 Nerves. — Most commonly the glosso-pharyngeal runs along the pneumogastric, or, more 
 correctly, along the anastomotic branch of the spinal accessory. Sometimes it is com- 
 pletely separated from these nerves, and merely communicates with them by means of 
 its pharyngeal branches. 
 
 The Branch for the Bigastricus and Stylc-hyoideus. — This branch comes off from the outer 
 side of the nerve, and bifurcates ; one of its divisions enters the posterior belly of the digas- 
 tricus, and the other supplies the stylo-pharyngeus and stylo-hyoideus. It has already been 
 stated that this branch anastomoses with the facial nerve in the digastric muscle. 
 
 The Carotid Filaments. — These are very numerous ; they descend along the internal 
 carotid artery, and, having reached the point of bifurcation of the common carotid, anas- 
 tomose with the carotid filaments of the superior cervical ganglion, and assist in form- 
 ing the arterial plexus. I have not been able to trace them below the bifurcation of the 
 common carotid. Some of these filaments are described as joining the cardiac nerves. 
 
 The Pharyngeal Branches. — These are two or three in number ; they anastomose with 
 the pharyngeal branches of the pneumogastric, to constitute the pharyngeal plexus. These 
 branches evidently supply the middle and superior constrictors. The filaments for the 
 latter muscles are reflected upward upon the posterior surface of the pharynx. 
 
 The tonsillar branches are very numerous, and form a sort of plexus. 
 
 The Lingual Branches. — After having given off the different branches above mentioned, 
 the glosso-pharyngeal, reduced to half its original size, enters the base of the tongue, and 
 then r-amifies ; some of its lingual branches lie close beneath the mucous membrane ; 
 others traverse the upper layers of the muscular substance of the tongue to proceed to 
 the mucous membrane in front of the preceding branches ; they are all intended for the 
 mucous membrane ; the internal branches proceed from without inward at the side of the 
 median line, while the external runs along the border of the tongue ; I have never seen 
 any filament terminating in the muscular fibres. 
 
 Function. — From its distribution, this nerve must be regarded as a motor nerve for the 
 pharynx, and a sensory nerve for the base of the tongue. 
 
 The Second Portion of the Eighth J^erve, or the Pneumogastric Jferve. 
 
 Dissection. — Lay open the back part of the foramen lacerum posterius, and afterward 
 examine the nerve in the different parts of its course successively. 
 
 The pneumogastric nerve, called also the vagus nerve, the par vagum, and the tenth era/- 
 niaX nerve of some modern authors, is the principal branch of the eighth nerve (8, fig. 301), 
 and is one of the most remarkable nerves in the body, both on account of the extent of 
 its distribution, and of the importance of the organs supplied by it. It supplies branches, 
 on the one hand, to the larynx, the lungs, and the heart ; and, on the other, to the pharynx, 
 the oesophagus, the stomach, and the solar "plexus. 
 
 It has already been stated that this nerve arises from the upper part of the medulla ob- 
 longata, upon the restiform bodies, and in a line with the posterior roots of the spinal 
 nerves ; that its filaments of origin converge, and then unite at first into seven or eight 
 fasciculi, and then into a single cord, which passes towards the foramen lacerum poste- 
 rius, through which it emerges from the cranium. The pneumogastric nerve then mns 
 vertically {p,fig. 301) in the neck along the vertebral column, enters the thorax, runs 
 along the oesophagus, with which it passes through the diaphragm, and terminates on 
 the stomach and in the solar plexus. 
 
 We shall now proceed to examine this nerve while it is within the foramen lacerum 
 
 * Arnold admits six filaments for the nerve of Jacobson, and, consequently, six small ducts as branches of 
 the canal of Jacol)son ; these six filaments consist of the three described in the text above, and of a twig for 
 the fenestra rotunda, one for the fenestra ovalis, and one for the Eustachian tube. I have distinctly seen the 
 twig for the fenestra ovalis, that is to say, a twig which reaches the margin of the fenestra ovalis, but cannot 
 be traced any farther. I have also seen the twig which passes to the Eustachian tube ; but I have not yet 
 been able to find the twig for the fenestra rotunda. 
 
THE PNEUMOGASTEIC NERVE. 845 
 
 posterius ; as it is emerging from that foramen ; and as it descends in the neck, in the 
 thorax, and in the abdomen. 
 
 The Pneumogastric Nerve witfdn th£ Foramen Lacerum Posterius. 
 
 At the foramen lacerum posterius, the pneumogastric nerve passes through the same 
 opening as the spinal accessory, which lies in contact with it ; a fibrous, cartilaginous, 
 or bony septum separates it from the glosso-pharyngeal, which lies in front of it ; and an- 
 other cartilaginous and often bony septum separates it from the internal jugular vein. 
 
 As it is passing through the foramen it presents a well-marked ganghonic structure ; 
 I would say, rather, a gray substance containing white nervous filaments, but without any 
 observable swelling : hence most anatomists have denied the existence of a ganglion at 
 this spot. 
 
 To this ganglion, the ganglion of the pneumogastric, which may be compared to the 
 Gasserian ganglion and to the inter-vertebral ganglia, the spinal accessory nerve is ap- 
 phed, and is connected with it by several very delicate filaments. I have already sta- 
 ted that, not unfrequently, the highest roots of the spinal accessory nerve join the pneu- 
 mogastric directly. 
 
 This ganglion gives off an anastomotic twig, which enters the petrosal ganglion of the 
 glosso-pharyngeal : I have not always found this filament ; it also gives an anastomotic 
 branch to the facial nerve, viz., the auricular branch of the pneumogastric of Arnold. This 
 branch might be called, the branch of the jugular fossa ; it can be very well seen through 
 the coats of the jugular vein when that vessel is laid open. It runs along the anterior 
 part of the jugular fossa, between it and the internal jugular vein, gives off an anasto- 
 motic twig to the nerve of Jacobson, enters the temporal bone through an opening in the 
 jugular fossa, near the styloid process, and traverses a very short canal, which conducts 
 it directly into the Fallopian aqueduct, in which it anastomoses with the facial nerve.* 
 
 The Pneumogastric Nerve, at its Exit from the Foramen Lacerum Posterius. 
 
 At its exit from the foramen lacerum posterius, the pneumogastric nerve presents the 
 appearance of a plexiform cord, which is often accompanied by the gray matter of the 
 ganglion for the space of about six lines or an inch. This plexiform cord has certain 
 important connexions with the spinal accessory, the ninth or hypo-glossal nerve, the glos- 
 so-pharyngeal nerve, and the superior cervical ganglion. 
 
 It is joined by one of the branches of bifurcation of the spinal accessory, which we 
 shall name the internal or anastomotic branch ol the spinal accessory nerve ; it becomes 
 applied to the pneumogastric nerve, and may be distinguished from it for a considerable 
 distance. 
 
 It also anastomoses with the hypo-glossal, at the point where it is crossed by that 
 nerve, and at other times above that point. This anastomosis, moreover, is subject to 
 great variety ; sometimes it takes place by a very small filament, at other times by two 
 or three twigs, which form a sort of plexus. 
 
 It also anastomoses with the glosso-pharyngeal. The examination of this anastomo- 
 sis, after the parts had been macerated in diluted nitric acid, enabled me to see that it 
 is not, properly speaking, effected with the pneumogastric nerve, but with the anasto- 
 motic branch of the spinal accessory. Nothing can be more variable than these anasto- 
 moses, which are sometimes wanting on one side, and which are rather frequently ef- 
 fected through the intervention of the pharyngeal branches. 
 
 Lastly, the pneumogastric nerve commu)iicates with the great sympathetic by one or 
 two branches in man and some mammalia ;t in the- other classes of animals the con- 
 nexion is so intimate that it is altogether impossible to separate the pneumogastric from 
 the superior cervical ganghon. 
 
 The connexions of the pneumogastric with the spinal accessory and superior cervical 
 ganghon are two very important points in its anatomy, t 
 
 The Pneumogastric Nerve in the Neck. 
 
 In the cervical region, the pnemnogastric nerve {p,figs. 298, 300, 301) is situated in 
 front of the vertebral column, the praevertebral muscles intervening between them, upon 
 the side of the pharynx and oesophagus, and between the internal and then the common 
 carotid, which are on its inner side, and the jugular vein, which is on its outer side ; it is 
 placed behind these vessels. It is closely applied to the carotid artery, being in the same 
 
 * I have seen this branch, immediately after its origin, enter the sheath of the glosso-pharyngeal nerve, run 
 along its ganglion, and then curve backward to enter the jugular fossa. Arnold, who first described this anas- 
 tomotic branch, represents it as divided into three filaments : an ascending, which anastomoses with the trunk 
 of the facial nerve ; a descending, which anastomoses with the posterior auricular branch of the same nerve ; 
 and a middle {u,fig. 299), which ramifies upon the external auditory meatus. 
 
 t I have seen the pneumogastric nerve communicate with the great sympathetic, by filaments which come 
 off at different heights from the cervical ganglion ; two proceeded from tlie upper part of the superior cervical 
 ganglion, and then ascended ; and two came from the lower part of the ganglion, and descended to unite with 
 the pneumogastric. I have met with a case in which the superior cervical ganglion was applied in its whole 
 extent so closely to the pneumogastric that it was impossible to separate them. 
 
 t [The pneumogastric also receives a filament from the anastomotic loop of the first and second cervical 
 iif rvcs (see p. 777). J 
 
846 NEUROLOGY. 
 
 sheath : it is separated from the cervical portion of the great sympathetic (i), which lies 
 behind and to the outer side of it, by a great quantity of cellular tissue. 
 
 During this course it supplies the pharyngeal branch, the superior laryngeal nerve, and 
 the cardiac filaments. 
 
 The Pharyngeal Branch, or Small Pharyngeal Nerve. — This is often double, and is then 
 distinguishable into a superior and an inferior ; it comes off at a little distance from the 
 foramen lacerum posterius, but its real origin is variable. In some cases it arises ex- 
 clusively from the pneumogastric ; at other times exclusively from the anastomotic 
 branch of the spinal accessory, which, as already stated, does not become immediately 
 blended with the pneumogastric ; and it often arises both from the pneumogastric and 
 the spinal accessory : lastly, the glosso-pharyngeal sometimes gives it a filament. It 
 passes behind the internal carotid, gives off" some carotid filaments, which join the more 
 numerous twigs from the glosso-pharyngeal, and then anastomoses with the ramifica- 
 tions of the glosso-pharyngeal, and with several large branches from the superior cervi- 
 cal ganglion, to form the pharyngeal plexus, which is one of the most remarkable plex- 
 uses in the body, and to which the varied and frequent nervous phenomena observed in 
 that region must be referred. I shall recur to this plexus when describing the great 
 sympathetic. 
 
 The Superior Laryngeal Nerve {x',fig. 301). — This is larger than the pharyngeal branch ; 
 it comes off" from the inner side of the pneumogastric* as a rounded cord, which may be 
 traced as high as the ganglion of the nerve ; it passes downward and inward upon the 
 side of the pharynx, behind the internal and external carotid arteries, which it crosses 
 obliquely : it then turns forward and inward to gain the thyro-hyoid membrane, passing 
 above the upper margin of the inferior constrictor of the pharynx ; it runs for some 
 time between the thyro-hyoid muscle and the thyro-hyoid membrane, perforates the lat- 
 ter at the side of the median line, and then enters the substance of the ar)rteno-epiglot- 
 tid fold of mucous membrane, where it terminates by dividing into a great number of fil- 
 aments. 
 
 During its course, it gives off a branch which is called the external laryngeal (y), and 
 which I have seen arise directly from the pneumogastric itself; this branch communi- 
 cates with the superior cervical ganglion by one or two filaments, and passes inward and 
 downward upon the side of the larynx. It gives off one or two filaments, which anasto- 
 mose with the superior cardiac nerve, behind the common carotid ; Haller calls this 
 communication between the external laryngeal and the great sympathetic the laryn- 
 geal plexus. \ The external laryngeal nerve also gives off several branches to the infe- 
 rior constrictor of the pharynx, some to join the pharyngeal plexus, and some twigs to 
 the thyroid gland ; it then passes downward and forward between the inferior constric- 
 tor and the thyroid cartilage, and terminates by ramifying in the crico-thyroid muscle. 
 
 The terminal expansion of the superior laryngeal nerve is remarkable for its radiated 
 arrangement ; it is preceded by a flattening and thickening of the nerve. These ex- 
 panded branches are all sub-mucous, and may be arranged into the anterior or epiglottid, 
 and the posterior. 
 
 The anterior or epiglottid branches are numerous and small ; they run upon the margin, 
 and on the fore part of the epiglottis ; some of them reach its free extremity, others run 
 between the fibro-cartilage of the epiglottis and the adipose tissue, called the epiglottid 
 gland ; some of them perforate the epiglottis, and ramify upon its posterior surface. 
 
 Among these anterior terminal filaments of the superior laryngeal nerve there is at 
 least one which runs forward under the mucous membrane covering the base of the 
 tongue, and may be traced as far as the two rows of glands, which are arranged like the 
 letter V. These filaments of the superior laryngeal nerve to the tongue are placed be- 
 tween the lingual branches of the right and left glosso-pharyngeal nerves, with which 
 they have probably been confounded. 
 
 The posterior or laryngeal filaments contained in the aryteno-epiglottid fold are more 
 numerous than the anterior branches ; they are divided into the mucous filaments, the 
 arytenoid filament, and the anastomotic or descending filameiit. 
 
 The mucous filaments are very numerous, and run upward in the aryteno-epiglottid 
 fold ; some of them lie beneath the external, and others beneath the internal layer of 
 mucous membrane of this fold. They are intended for these two layers, and they ter- 
 minate, for the most part, at the superior orifice of the larynx : their number explains 
 the exquisite sensibility of this opening. Some of these mucous filaments may be traced 
 into the substance of the arytenoid glands. 
 
 The filatnent for the arytenoid muscle is very liable to be confounded with the mucous 
 
 * It arises, therefore, on the opposite side to the anastomotic branch of the spinal accessory, which has not 
 appeared to me to assist in its formation. I have seen the superior laryngeal arise by two roots, the larger of 
 which came from the pneumogastric, while the other, which was very small, came from the glosso-pharyn- 
 geal. It appears to me that M. BischofTs remarks concerning the origin of the superior laryngeal nerve on a 
 level with tlie spinal accessory, would apply to the pharyngeal branch of the pneumogastric. 
 
 t The superior laryngeal nerve (x',Jig. 301) forms a loop behind the carotids, like tliat formed by the hypo- 
 glossal (d) in front of them, but lower down in the neck ; that portion of the nerve which runs between the 
 thyro-hyoid membrane and the thyro-hyoid muscle is exceedingly tortuous in some positions of the larynx. 
 
THE PNEUMOGASTRIC NERVE IN THE THORAX, ETC. 847 
 
 filaments ; it perforates the muscle from behind forward, and is partly distributed to it 
 and partly to the lining membrane of the larynx. 
 
 The descending or anastomotic filament, which is small, but of variable size, descends 
 vertically, between the mucous membrane on the one hand, and the thyro- and crico- 
 arytenoid muscles on the other, gains the posterior surface of the cricoid cartilage, and 
 anastomoses upon it with the recurrent laryngeal nerve. This remarkable anastomosis 
 was known to Galen.* 
 
 Thus, the superior laryngeal nerve chiefly belongs to the mucous membrane of the 
 larynx ; but it gives branches to the arytenoid and crico-thyroid muscles : the branch 
 for the latter comes from the external laryngeal division of this nerve. 
 
 The Cardiac Branches of the Pneumogastric Nerve of the Neck. — These vary both in 
 number and size in different subjects, and even upon the two sides of the same body : 
 they come off at different heights from the trunk of the pneumogastric ; some of them, 
 after a course of variable extent, join the superior cardiac nerves, either in the neck or 
 in the thorax ; the others pass directly to the cardiac plexus. The most remarkable of 
 the cervical cardiac branches of the pneumogastric is that which comes off at the lower 
 part of the neck, a little above the first rib ; on the right side, it descends in front of the 
 common carotid, and then in front of the brachio-cephalic artery, below which it anasto- 
 moses with the superior cardiac nerve. On the left side, it passes in front of the arch 
 of the aorta, and anastomoses below that vessel with the superior cardiac nerve of that 
 side. This branch sometimes goes directly to the cardiac plexus : it is sometimes double. 
 
 The Pneumogastric Nerve in the Thorax. 
 
 The thoracic portion of the pneumogastric nerve presents this peculiarity, that it differs 
 remarkably on the right and left sides. 
 
 On the right side, the nerve {p,fig- 302) enters the thorax between the sub-claviaa 
 vein and artery : lower down, it passes behind the brachio-cephalic vein and the supe- 
 rior cava, and behind the phrenic nerve, at the side of the trachea, or, rather, in the 
 groove between the trachea and oesophagus : it then passes behind the root of the lung, 
 where it becomes flattened and enlarged, gives off a great number of branches, and ap- 
 pears to expand, in order to unite in a different arrangement. Below the root of the 
 lung the right pneumogastric is always divided into two flattened branches, which run 
 along the right side of the cesophagus, join together at a short distance from the dia- 
 phragm, and pass behind the cesophagus, with which canal the common trunk enters the 
 abdomen. 
 
 On the left side, the pneumogastric enters the thorax between the common carotid and 
 the sub-clavian artery, in the triangular interval between those vessels, internal to and 
 then behind the phrenic nerve, behind the brachio-cephalic vein, and to the left of the 
 arch of the aorta ;t it then passes behind the left bronchus, upon which it ramifies, and 
 unites again into one or two branches, which pass in front of the oesophagus, and enter 
 the abdomen with it. 
 
 In the thorax the pneumogastric gives off the recurrent or inferior laryngeal nerve, a 
 cardiac branch, some tracheal and oesophageal branches, and branches to the anterior and 
 posterior pulmonary plexuses. 
 
 The Recurrent or Inferior Laryngeal Nerve.t 
 
 This nerve (r, fig. 302), so called on account of its reflected course, arises in front of 
 the arch of the aorta on the left side, and of the sub-clavian artery on the right side : it 
 is sometimes so large that it may be regarded as resulting from the bifurcation of the 
 pneumogastric : it is reflected below and then behind the arch of the aorta on the left 
 side, and the sub-clavian artery on the right, so as to form a loop or arch, which has its 
 concavity turned upward, and which embraces the corresponding vessel. Having thus 
 changed its course from a descending to an ascending one, the recurrent nerve enters 
 the groove {q,fig. 301) between the trachea and the oesophagus, and continues to ascend 
 as high as the lower border of the inferior constrictor muscle of the pharynx ; it then 
 passes beneath that muscle, gives some filaments to it, runs behind the lesser cornu of 
 the thyroid cartilage and the crico-thyroid articulation, along the outer border of the 
 posterior crico-arytenoid muscle, and terminates by ramifying in the muscles of the 
 larynx. 
 
 During its course, the recurrent nerve gives off the following collateral branches : at 
 the point of its reflection, it gives several cardiac filaments, which unite with the cardiac 
 branches of the pneumogastric and great sympathetic. It is important to remark the 
 intimate connexion which exists between the recurrent and the cardiac nerves : some 
 very considerable anastomoses are almost always found between the superior and infe- 
 
 * See note, p. 848. 
 
 t The relation of the pneumogastric with the arch of the aorta explains the stretching and atrophy of this 
 nerve in aneurisms of that portion of the vessel. 
 
 1 Those anatomists who regard the superior laryngeal nerve as a dependance of the spinal accessory be- 
 lieve that the inferior or recurrent laryngeal has a similar origin. I may repeat, and with still more reason, in 
 reference to this nerve, what I have already stated in regard to the superior laryngeal, that it is impossible to 
 '«monstrate this continuity by dissection. 
 
848 NEUROLOGY. 
 
 rior cardiac nerves and the recurrent nerve : sometimes, indeed, the recurrent nerve 
 forms the point at which the superior and middle cardiac nerves meet, and from which 
 the inferior cardiac nerve is given off; the anastomoses between the recurrent and car- 
 diac nerves sometimes form a true plexus. 
 
 The recurrent also gives oesophageal branches, which are much more numerous on the 
 left than on the right side, so that the left recurrent nerve is much smaller in the larynx 
 than the right nerve. 
 
 It also gives tracheal branches, which chiefly supply the posterior or membranous por- 
 tion of that canal. 
 
 And, lastly, some pharyngeal filaments, all of which are destined for the inferior con- 
 strictor. 
 
 Excepting an anastomotic branch* for the superior laryngeal nerve, all of the terminal 
 branches of the recurrent nerve are intended for the muscles of the larynx, and are thus 
 distributed : 
 
 The branch for the posterior crico-arytenoid simply enters that muscle. 
 
 The branch for the arytenoid, runs between the cricoid cartilage and the posterior crico- 
 arytenoid muscle, and then ramifies in the arytenoid. It has already been stated that 
 the last-named muscle is also supplied by the superior laryngeal nerve. 
 
 The branch for the lateral crico-arytenoid and thyro-arytenoid muscles is the true termina- 
 tion of the nerve ; it passes on the outer side of these two muscular bundles, which, as 
 formerly stated, constitute a single muscle in the human subject, and then enters them 
 by very delicate filaments. I have distinctly seen a very delicate filament entering the 
 crico-th)Toid articulation. 
 
 After the pneumogastric has given off the recurrent nerve, and often before doing so, 
 it furnishes certain cardiac branches (thoracic cardial) ; these are subdivided into the 
 pericardial, which run upon the outer surface of the pericardium, and are lost in it and 
 in the cellular tissue which replaces the thymus ; and into the cardiac branches, properly 
 so called, which assist in the formation of the cardiac plexus. 
 
 The pneumogastric also gives off certain anterior pulmonary branches, which run in 
 front of the bronchus and of the pulmonary arteries and veins, cross obliquely over them, 
 and then enter the substance of the lung, following the ramifications of the air-tubes and 
 bloodvessels ; these pulmonary branches form what is called the anterior pulmonary plex- 
 us. I have seen several of them extend some considerable distance beneath the serous 
 membrane, covering the inner surface of the lungs, before they entered the substance 
 of those organs. 
 
 Behind the bronchus, and along the oesophagus, the pneumogastric nerve gives off 
 posterior branches, consisting of a great number of esophageal branches ; of some tracheal 
 branches, which principally supply the back or membranous portion of the trachea ; and, 
 lastly, of posterior pulmonary or bronchial branches, which form the posterior pulmonary 
 plexus. 
 
 The posterior pulmonary plexus is one of the most remarkable in the body ; in it the 
 pneumogastric nerve appears to be decomposed and expanded ; there is a right and a 
 left pulmonary plexus. The left is much larger than the right. The two plexuses are 
 not independent of each other, but are connected by free anastomoses : this remarkable 
 disposition establishes a community of function between the two nerves, and explain* 
 how one of them may supply the place of the other. 
 
 The pulmonary plexuses, which are completed by filaments from the great sympathetic, 
 are situated behind the root of each lung, or, to speak more exactly, behind the bronchi 
 (whence the name of bronchial plexuses). A few of the twigs emerging from them follow 
 the pulmonary arteries, and appear to be lost in their coats ; the others accompany the 
 bronchi, some of them passing behind these canals, and others, being reflected forward 
 in the angles formed by their bifurcation, run along their anterior aspect, and terminate 
 in their parietes. They may be traced as far as the ultimate ramifications of the aii- 
 tubes. In large animals they can be easily seen entering the circular muscular fibres 
 which surround the bronchial tubes, t 
 
 Below the pulmonary plexus, the pneumogastric merely gives off certain cesophagcal 
 branches, which surround the oesophagus in very great numbers. The right and left 
 pneumogastric nerves anastomose with each other ; but the communicating arches do 
 not constitute those circular anastomoses, which have been so decidedly said to explain 
 the pain caused by swallowing too large a morsel of food. 
 
 The Pneumogastric Nerve in the Abdomxn. 
 The two pneumogastrics enter the abdomen with the oesophagus, the left nerve being 
 in front and the right nerve behind that canal, and are distributed in the following manner : 
 
 * [This anastomotic branch is superficial, and joins the descending filament from the superior laryngeal 
 nerve, beneath the mucous membrane on the back of the larynx, and sometimes sends filaments into the ary- 
 tenoid muscle ; there is, generally, a second anastomosis between the superior and inferior laryngeal nerves 
 on the side of the larynx, between the thyroid cartilage and the thyro-arytenoid muscle.] 
 
 t I have seen a nerve from the pulmonary plexus pass through some of the fibres of the oesophagus and ram- 
 ify iu the aorta. 
 
SPJNAL ACCESSORY NERVE OF WILLIS. 849 
 
 The left nerve {q,fig. 302), which is situated in front of the cardia, expands into a very- 
 great number ot diverging filaments, some of which extend over the great cul-de-sac, 
 and others over the anterior surface of the stomach ; but the greater number gain the 
 lesser curvature, and divide into two sets or groups ; one of these leaves the lesser cur- 
 vature, enters the gastro-hepatic omentum, is conducted by it to the transverse fissure 
 of the liver, and enters that gland. The other group continues in the lesser curvature, 
 and may be traced as far as the duodenum. 
 
 The right pneumogastric (p'), situated behind the cardia, gives a much smaller number 
 of branches to the stomach than the left, and joins the solar plexus (z), of which it may 
 be regarded as one of the principal origins. 
 
 Summary of the Distrilmtion of the Pneumogastric Nerve. — This nerve, it wiU be seen, 
 has an extremely complicated distribution. 
 
 Within the foramen lacerum posterius, it anastomoses with the spinal accessory ; with 
 the facial nerve by means of the auricular branch of Arnold, or the branch of the jugular 
 fossa ; and with the nerve of Jacobson, and, therefore, with the glosso-pharyngeal nerve, 
 by a twig from the same auricular branch. 
 
 At its exit from the foramen lacerum posterius, it anastomoses with a Isirge branch of the 
 spinal accessory ; with the hypo-glossal ; with the glosso-phyrangeal ; and with the su- 
 perior cervical ganglion. 
 
 In the neck, it gives off the pharyngeal branch or small pharyngeal nerve, the superior 
 laryngeal nerve, and the superior cardiac branches of the pneumogastric. 
 
 In the thorax, it gives off the recurrent or inferior laryngeal nerve, which supplies 
 some cardiac, oesophageal, pharyngeal, tracheal, and laryngeal branches ; the inferior 
 cardiac branches ; and the pulmonary or bronchial branches. 
 
 In regard to its structure, the pneumogastric differs essentially from the other cerebro- 
 spinal nerves, by the tenuity of its filaments and by their plexiform arrangement ; and 
 in both of these particulars, as well as in its distribution, it rather resembles the nerves 
 of organic than those of animal life. In the description of the sympathetic it will be 
 seen how intimate are its relations with the pneumogastric nerve. 
 
 Functions of the Pneumogastric. — From the manner in which the pneumogastric is dis- 
 tributed, it follows that it is a nerve both of sensation and ot motion ; for it supplies 
 both the lining membrane of the respiratory and digestive passages, and the muscles 
 and muscular coats of the same canals. Anatomy does not confirm the ingenious idea 
 of Bischoff, that the pneumogastric is essentially a nerve of sensation, and that the por- 
 tion which appears to be motor really belongs to the spinal accessory. Physiologists 
 have studied the influence of the pneumogastric upon the larynx, the lungs, the heart, 
 and the stomach in an infinite variety of ways ; it appears, from some experiments 
 which I made upon this subject, that animals in which both pneumogastrics are simul- 
 taneously cut die almost immediately, when they are permitted to eat as much as they 
 please ; for, the contractility of the stomach and oesophagus being destroyed, the food, 
 after having filled the stomach, distends the oesophagus, and passes from it into the larynx. 
 
 The Third Portion of the Eighth Jferve, or the Spinal Accessory JN'&rve oj 
 
 Willis. 
 
 We have already described the very remarkable origin of the spmal accessory nerve 
 at the side of the cervical portion of the spinal cord, between the anterior and posterior 
 roots of the spinal nerves, or, rather, immediately in front of the posterior roots, of 
 which it appears to be a dependance : we particularly alluded to the arrangement of its 
 highest filaments of origin, which come from the restiform bodies, and are continuous 
 above with the roots of the pneumogastric, so that they sometimes even join that nerve, 
 and below with the posterior roots of the spinal nerves. 
 
 Lastly, we have pointed out the varieties of its origin, its connexions with the first 
 pair of cervical nerves, of which it almost always forms the posterior roots, its ascend- 
 ing course to the foramen magnum, through which it enters the cranium, and its exit 
 from the scull by the foramen lacerum posterius. 
 
 It emerges from the foramen lacerum posterius by an opening quite distinct from that 
 for the glosso-pharyngeal, but common to itself and the pneumogastric nerve, behind 
 which it is situated {9, fig. 301). While passing through the foramen lacerum poste- 
 rius, it lies in contact with the ganglionic enlargement of the pneumogastric, and is con- 
 nected with the ganglion by very delicate filaments, but it neither assists in the forma- 
 tion of that enlargement, nor is blended with it : at its exit from the foramen it divides 
 into two branches of equal size ; an internal or anastomotic, which remains in contact 
 with the pneumogastric, and is distributed with it, and a muscular branch* (cut off in 
 %. 301). 
 
 The Anastomotic Branch. — So intimately are the spinal accessory and pneumogastric 
 nerves connected, or, as it -were, fused together, that, up to the time of Willis, they were 
 
 " It is well to observe, that as they are passing through the foramen lacerum posterius, the pneumogastric 
 and spinal accessory nerves adhere to the dura mater, in the iame manner as the Gasserian ganglion. 
 
 5 P 
 
850 NEUROLOGY. 
 
 regarded as a single nerve. Willis first described the former, perhaps erroneou§^^, as a 
 separate nerve, under the name of nervus accessorius ad par vagum, sive nerviis spinalis. 
 In an excellent thesis, published in 1822,* M. Bischoff endeavoured to prove that the 
 pneumogastric or par vagum and spinal accessory form but a single nerve, analogous to 
 the spinal nerves in every respect ; the spihal accessory being the nerve of motion, and 
 the par vagum the nerve of sensation : " Nervus accessorius Willisii est nervus moto- 
 rius, atque eandem habet rationera ad nervum vagum quam antica radix nervi spinalis 
 ad posticam. Omnis motio cui vagus praeesse videtur, ab ilia portione accessorii quae 
 ad vagum accidit, efEcitur. Itaque vox quoque, sive musculorum laryngis et glottidis 
 motus, ab accessorio pendet, et eo nomine accessorius nervus vocalis vocari potest." 
 
 To this view there are serious objections : in the first place, it is opposed to the law 
 that the anterior roots preside over motion and the posterior over sensation ; for the 
 filaments of origin of the spinal accessory evidently form part of the posterior roots. 
 Again, how can it be supposed that two nerves, which, like the spinal accessory and 
 pneumogastric, arise so distinctly from the same line, that it is often difficult to separate 
 them, can have such opposite functions ! 
 
 Must we suppose that the law which regulates the anterior and posterior roots of the 
 spinal nerves ceases to operate at the medulla oblongata 1 or must we admit, with Ar- 
 nold, that there is not only a decussation of fibres from side to side in the medulla ob- 
 longata, but also from before backward, so that the posterior columns of the medulla ob- 
 longata become the motor and the anterior the sensory 1 Still, even with this hypothe- 
 sis, it must be remembered that the spinal accessory arises in part below the point where 
 this antero-posterior decussation is supposed to exist. There evidently is an antero- 
 posterior decussation opposite to the two anterior pyramids, as I have elsewhere stated 
 (see Medulla Oblongata), but the other columns of the spinal cord are not concerned in it. 
 
 However this may be, the anastomotic branch of the spinal accessory may be traced, 
 after maceration in dilute nitric acid, along the outer side of the pneumogastric. In a 
 great number of cases, it evidently gives off the small pharyngeal nerve, which sometimes 
 arises exclusively from the pneumogastric, and sometimes from both the pneumogastric 
 and the spinal accessory. Scarpa declares the last arrangement to be constant and 
 normal, and has represented it in several figures. In some subjects, the spinal accessory 
 appears to have no share in the pharyngeal nerve, but then its anastomotic branch be- 
 comes applied to the pneumogastric below the origin of the pharyngeal nerve. 
 
 The anastomotic branch appears to me to have no share in the formation of the supe- 
 rior laryngeal nerve ; and the same is the case with regard to the recurrent nerve. It 
 appears to me anatomically impossible to prove the continuity of the spinal accessory 
 and the superior and recurrent laryngeal nerves ; I cannot, therefore, admit that the spi- 
 nal accessory supplies the intrinsic muscles of the larynx. 
 
 The spinal accessory generally gives off a number of twigs, which unite in front of the 
 reddish, and, as it were, ganglionic trunk of the pneumogastric nerve, to form a small 
 plexus, which adheres to that nerve, and ends in the hypo-glossal nerve. 
 
 Lastly, there are so many varieties in the mode of communication between the pneu- 
 mogastric and spinal accessory nerves, that it is extremely difficult to refer them to any 
 general law. 
 
 The Muscular Branch. — This nerve descends vertically between the internal jugular 
 vein and the occipital artery, beneath the digastric and stylo-hyoid muscles ; it runs back- 
 ward and outward {t, figs. 285, 298), beneath the sterno-mastoid, generally perforating 
 that muscle, but sometimes merely running along its deep surface, passes obliquely 
 across the supra-clavicular triangle, and terminates in the deep surface of the trapezius. 
 
 While perforating the sterno-mastoid, the spinal accessory nerve gives several branches 
 to that muscle, which anastomose with others from the third cervicd nerve, and form a 
 sort of plexus within the muscle. 
 
 On emerging, somewhat reduced in size, from the sterno-mastoid, it receives a branch 
 {v, fig. 298) from the anastomosis, between the second and third cervical nerves, by which 
 its size is greatly increased : it assists in the formation of the cervical plexus, and some- 
 times of the posterior auricular nerve. 
 
 Having reached the anterior surface of the trapezius, it receives two considerable 
 branches, derived from the third, fourth, and fifth cervical nerves, which appear to me 
 to re-enforce it. It gives off ascending filaments to the occipital portion of the muscle ; 
 and descending filaments, which continue in the original course of the nerve in front of 
 the muscle, approach its scapular attachments, and may be traced down to its inferior 
 angle. The muscular branch of the spinal accessory belongs exclusively to the sterno- 
 mastoid and trapezius muscles. It has been incorrectly stated that it supplies other mus- 
 ■des, such as the rhomboidei, the levator anguli scapulae, the complexus, the splenius, 
 and the sub-scapularis, and that it is also distributed to the skin. 
 
 In front of, or, rather, in the substance of the trapezius, the spinal accessory anasto- 
 fjoaoses with the posterior branches of the spined nerves. 
 
 * Ne-vi Accessorii Willisii Anatomia etPhysiologia. Bischoff. Darmstadii. 
 
THE HYPO-GLOSSAL NERVE. 851 
 
 Summary. — ^The spinal accessory gives branches to the stemo-mastoid, the trapezius, 
 and the phar)Ttx ; it is believed also to send some to the larynx by means of its anasto- 
 motic branch with the pneumogastric. It communicates with the second, third, fourth, 
 and fifth cervical nerves. 
 
 Function. — In reference to its muscular branch, Sir C. Bell has classed the spinal ac- 
 cessory among the respiratory nerves, under the name of the superior respiratory nerve of 
 the trunk ; for, according to that anatomist, it arises from the lateral column of the cord, 
 between the anterior and posterior columns. 
 
 With regard to the anastomotic branch of this nerve, which becomes blended with the 
 par vagum, M. BischofT lays down the following proposition (page 95) : " Nervum acces- 
 sorium nimirum nervum motorium esse, ideoque in partes vagi adscisci, ut motus, qui- 
 bus hie qui sensificus tantummodo nervus est, praeesse videatur, ipse perficiat : eundem 
 ergo praeesse motibus quoque musculorum laryngis, indeque nerviun esse vocalem.". 
 This idea, which was suggested to him by theory, he endeavoured to confirm by experi- 
 ment. The section of all the roots of the spinal accessory proved to be very difficult ; 
 but, after many fruitless attempts, he at length succeeded in dividing them on both 
 sides. The hoarseness produced by section of all the roots of the right side gradually 
 increased as he divided those of the left side, and when all had been cut, the natural 
 voice of the animal was changed to a very hoarse sound, which could not be called the 
 voice. 
 
 I have already said that anatomy affords no proof that the laryngeal nerves are derived 
 from the spinal accessory ; nor does it show that the muscular fibres of the bronchi, 
 oesophagus, and stomach, receive their filaments from it. 
 
 The Ninth Pair, ok Hypo-glossal Nerves. 
 
 The hypo-glossal, or great hypo-glossal nerve, the ninth cranial, or the twelfth nerve 
 of some modem authors, arises on each side from the furrow between the olivary and 
 pyramidal bodies, by a row of filaments collected into two very distinct fasciculi, which 
 proceed to the anterior condyloid foramen (q, fig. 296), perforate the dura mater separ- 
 ately, and join together so as to emerge from the canal in the form of a rounded cord.* 
 
 After leaving the anterior condyloid canal, the hypo-glossal nerve (d, fig. 301) descends 
 vertically between the internal carotid, which is on its inner side, and the internal jugu- 
 lar on its outer side. At first it lies behind the pneumogastric (8 to p) ; it then crosses 
 very obliquely over the outer side, and lower down it gets in front of that nerve, around 
 which, therefore, it describes a semi-spiral. 
 
 Having arrived below the posterior belly of the digastric muscle, the hypo-glossal 
 changes its direction and runs forward and downward {d, fig. 300), crossing in front of 
 the internal and external carotids [and hooking beneath the occipital artery] ; it is then 
 reflected upward to reach the under surface of the tongue {d, near x), and thus describes 
 a loop having the concavity turned upward, parallel to and below the digastricus, and 
 almost ten lines above the os hyoides. 
 
 Relations. — It is situated deeply in its vertical portion, where it runs along the verte- 
 bral column, becomes superficial in its middle portion (d, fig. 298), where it is merely 
 separated from the skin by the platysma and the prominence of the sterno-mastoid, and 
 again becomes deep-seated anteriorly, where it rests on the hyo-glossus muscle, and is 
 covered by the anterior belly of the digastricus and by the stylo-hyoideus, and then by 
 the sub-maxillary gland and the mylo-hyoideus, after which it enters the genio-glossus, 
 and is lost in the substance of the tongue. 
 
 The relations of the hypo-glossal nerve and the lingual artery are worthy of remark. 
 The nerve is at first parallel to and above the artery, is soon separated from it by the 
 hyo-glossus, and then rejoins it in front of that muscle. In the substance of the tongue, 
 the artery lies to the outer side of the genio-glossus, while the nerve runs forward 
 through the fibres of the muscle. 
 
 The Collateral Branches of the Hypo-glossal Nerve. 
 
 Some of these are anastomotic. Thus, as it crosses the three divisions of the eighth 
 nerve, the hypo-glossal lies in contact with the pneumogastric nerve, with which it 
 sometimes communicates by very delicate filaments. Most commonly the anastomosis 
 between these two nerves forms a true plexus, t This communication is sometimes 
 eftected with the anastomotic branch of the spinal accessory, sometimes with the pneu- 
 mogastric itself 
 
 The hypo-glossal is also connected by a very small anastomotic twig to the superior 
 cervical ganglion. 
 
 It also receives three filaments from the nervous loop formed by the union of the first 
 and second cervical nerves, namely, two from the first nerve and one from the second. 
 The superior filament from the first nerve ascends, an arrangement which it is difficult 
 to understand, for it passes in a direction towards the roots of the hypo-glossal ; if it be 
 
 * The vertebral artery is situated in front nf the filaments of the hypo-glossal. 
 
 t [In connexion with this fact, it may be observed that the descendens noni (a branch of the hypo-|floaaal 
 ttBr\-ol sometimes arises in part or entirely from the pneumogastric, lower down in the neck.] 
 
85S NEUROLOGY. 
 
 supposed that this filament is derived from the hypo-glossal, then it is directed towards 
 the roots of the first cervical nerve. 
 
 Opposite to the anterior border of the hyo-glossus it gives off a very remarkable anas- 
 tomotic branch, which forms an arch with the lingual nerve. 
 
 The other collateral branches which it gives off are the descending branch ; a small 
 muscular infra-hyoid branch ; and the branches for the hyo-glossvs and stylo- glossus. 
 
 The descending branch {ramus descendens noni, h,figs. 298, 300, 301). This is the most 
 remarkable branch of the hypo-glossal nerve.* It comes off at the point where the 
 nerve changes its direction, descends vertically in front of the internal carotid and then 
 of the common carotid, curves outward, and anastomoses upon the internal jugular vein 
 with the descending branch of the cervical plexus {z,fig. 298), so as to form a loop, hav- 
 ing its concavity turned upward. From the convexity of this loop two branches proceed, 
 .of which one is distributed to the omo-hyoid, while the other (5^) divides into two twigs, 
 one of which enters the outer border of the stemo-hyoid, while the other penetrates the 
 deep surface of the sterno-thyroid muscle. I have seen one of these branches come di- 
 rectly from the hypo-glossal. t 
 
 It is equally important to study both the mode of origin and anastomosis of the de- 
 scending branch of the ninth ner^'e.t The origin of this branch is, in fact, almost en- 
 tirely from the anastomotic branches of the first and second cervical nerves, which, after 
 having been in contact with the hypo-glossal, are given off from it to constitute the de- 
 scending branch. This arrangement is especially evident in preparations that have been 
 macerated in diluted nitric acid. I should state, however, that it is not equally evident 
 in all subjects ; and that some filaments, derived from the hypo-glossal itself, always join 
 those from the cervical nerves. It has appeared to me that the most internal of the fila- 
 ments derived from the hypo-glossal nerve itself followed a retrograde course ; that is to 
 say, that it ran from below upward, as if it arose at the terminal extremity of the hyi^o- 
 glossal, and then left that nerve to join the descendens noni at the point where that 
 branch is given off. 
 
 The branches from the first and second cervical nerves to the hypo-glossal should be 
 regarded as late origins of that nerve, which is sensibly increased in size after being 
 joined by them. I have seen the third and even the fourth cervical nerve assist in the 
 formation of the descendens noni ; the branch from the fourth nerve arose partly from 
 the phrenic. 
 
 The mode of anastomosis of the descendens noni with the descending branch of the 
 cervical plexus, or, rather, of the third cranial nerve, is subject to much variety. 
 
 The following is the most frequent arrangement : 
 
 All the filaments composing these two descending branches unite together, with the 
 exception of the uppermost filament, which describes a loop having its concavity turned 
 upward, and resembhng a vascular anastomosis : so that, if we suppose it to be derived 
 from the loop of the Kypo-glossal, it would be directed towards the origin of the cervical 
 nerves ; and if, on the contrary, we suppose it to arise from the cervical nerves, it would 
 be directed towards the origin of the hypo-glossal. This arrangement, which I have had 
 the opportunity of observing in many parts of the nervous system, appears to me to con- 
 stitute a mode of anastomosis well worthy the attention of physiologists. I am induced 
 to regard it as intended to establish connexions between the different points of the spinal 
 cord.^ 
 
 * See note, last page. 
 
 t [Another branch is described and figured by Arnold as descending in front of tlie vessels, and joining the 
 cardiac nerves in the thorax.] 
 
 X There are certain cases in which the descendens noni is analyzed by nature ; namely, when the branch 
 from the second cervical nerve is not applied to the hypo-glossal, but remains at a distance from it. In this 
 case, the filaments derived from the hypo-glossal join themselves to this branch ; one of them ascends towards 
 the origin of the second cervical nerve, and the others proceed towards its termination. In one case, the hypo- 
 glossal gave a very small twig to the first cervical nerve, before receiving its accustomed branch from that 
 nerve ; the descending branch from the cervical plexus was replaced by tEree branches derived from the first, 
 second, third, and fourth cervical nerves, which formed, together with the descendens noni and its branches, a 
 succession of loops, in front of the external and common carotids. In another case, the three superior cervical 
 nerves assisted in forming the descendens noni. The following is a detailed description of that case, which 
 throws considerable light upon the connexions between the hypo-glossal and cervical nerves. One large branib 
 proceeded from the anastomotic arch of the first and second cervical nerves ; this large branch, as soon as 't 
 reached the hypo-glossal nerve, divided into three filaments of unequal size : an ascending, which was directed 
 towards the origin of the hypo-glossal nerve ; a middle, which became blended with that nerve ; and a descend- 
 ing, which was the largest, and which merely ran along in contact with the same nerve. At the point where 
 this last-named filament left the hypo-glossal to form the descendens noni, it evidently received a twig from 
 the hypo-glossal itself, which came from the lower part of that nerve, and was reflected upon the descendens 
 noni in a retrograde manner, so that this twig, derived from the hypo-glossal, had one end at the terminal ex- 
 tremity of that nerve, i. e., in the muscles of the tongue, and the other end in the muscles of the infra-hyoid 
 region. In this same case, the descending branch of the second cervical nerve divided into three filaments, 
 one of which joined the hypo-glossal nerve, another formed an anastomotic arch with the third cervical nerve, 
 while the third filament passed downward to assist m forming the descending branch of the cervical plexus. 
 Lastly, the third cervical nerve in this case gave off an ascending branch, which anastomosed with the seo(md, 
 and a descending branch, which assisted in forming the descending branch of the cenical plexus ; there were 
 therefore two loops or arches, one internal and the other external ; they were situated opposite to the bifurca- 
 tion of the common carotid artery. 
 
 i, This mode of anastomosis may, perhaps, have some relation to that reflex action of the spinal cord, which 
 
GENERAL VIEW QF THE CRANIAL NERVES, 853 
 
 The Small Muscular Branch of the Infra-hyoid Region. — This nerve comes off at the 
 posterior border of the hyo-glossus, and ramifies in the upper part of the muscles of the 
 infra-hyoid region ; a small transverse filament runs along the hyoid attachments of these 
 muscles. This small nerve may be regarded as an accessory to the descendens noni. 
 
 'The Branches for the Hyo-glossus and Stylo-glossus. — As the hypo-glossal nerve comes 
 into contact with the hyo-glossus, it becomes flattened and widened, and gives off sev- 
 eral ascending branches, most of which ramify in the hyo-glossus, though several end in 
 the stylo-glossus. 
 
 The Terminal Branches of the Hypo-glossal Nerve. 
 
 Opposite to the anterior border of the hyo-glossus the hypo-glossal nerve gives off 
 some twigs to the under surface of the genio-hyoideus ; it then enters the genio-hyo- 
 glossus, and expands (d, near x, fig. 300) into a great number of filaments, which run for- 
 ward, perforate that muscle at successive points, and are lost in the substance of the 
 tongue. It is impossible to follow these filaments to the papillary membrane of the 
 tongue. Some of them anastomose with the lingual («) nerve, a branch of the inferior 
 maxillary division of the fifth ; several accompany the lingual artery. 
 
 The relations of the lingual portions of the hypo-glossal nerve with the lingual of the 
 fifth are worthy of attention. The lingual nerve occupies the under part of the border 
 of the tongue, runs along the stylo-glossus, and may be traced as far as the apex of the 
 organ : it is sub-mucous in the whole of its extent. The hypo-glossal nerve is situated 
 on a much lower plane, and occupies the under surface of the tongue, on each side of 
 the median Une. 
 
 Function. — The hypo-glossal is a muscular nerve : it regulates the movements of the 
 tongue, while the lingual of the fifth and the glosso-pharyngeal confer sensibility upon it. 
 This fact is most clearly established by anatomical, physiological, and pathological ob- 
 servations. Like all nerves having a simple distribution, the hypo-glossal has not a 
 plexiform structure. 
 
 General View of the Cranial Nerves. 
 
 All the spinal nerves present the greatest regularity in arising from two series of roots, 
 in having a ganglionic enlargement on their posterior roots, and even in their course 
 and termination, the differences or modifications of which depend on the different struc- 
 ture of the parts to which they are distributed ; but the greatest irregularity appears to 
 prevail in reference to the origin, the course, and the termination of the cranial nerves. 
 From the comparison which has been made between the scull and the vertebrae, and 
 from the possibility of resolving the bones of the cranium into a certain number of cra- 
 nial vertebrae, anatomists have entertained the idea of drawing a parallel between the 
 cranial and the spinal nerves. It has been conceived that the number of cranial nerves 
 ought to be regulated by the number of cranial vertebras admitted by different anato- 
 mists ; and, moreover, that in order to draw a fair comparison between these two sets 
 of nerves, the special nerves of the face, namely, the olfactory, the optic, and the auditory 
 nerves, should be entirely disregarded. 
 
 Now we have already shown (see Osteology) that there are three cranial vertebrae, 
 between which there are two inter- vertebral foramina ; that the anterior inter-vertebral 
 foramen is represented by the sphenoidal fissure, to which we must annex the foramen 
 rotundum and the foramen ovale ; and that the posterior inter- vertebral foramen is rep- 
 resented by the foramen lacerum posterius, together with the anterior condyloid foramen. 
 
 This being premised, we shall admit two pairs of cranial nerves, an anterior and a 
 posterior. 
 
 The posterior cranial pair consists on each side of the eighth and ninth nerves, namely, 
 of the pneumogastric, glosso-pharyngeal, spinal accessory, and hypo-glossal nerves. 
 The pneumogastric and the glosso-pharyngeal, each of which has a ganglion analogous to 
 the inter- vertebral ganglia, represent the posterior roots of a spinal nerve, while the spi- 
 nal accessory and the hypo-glossal, which have no ganglion, represent the anterior root. 
 The two last-named nerves are exclusively motor, while the pneumogastric and the 
 glosso-pharyngeal appear to me to be mixed nerves, that is, both sensory and motor. 
 
 The anterior cranial pair is composed on each side of the fifth nerve, the ganglion of 
 which is quite analogous to the inter- vertebral ganglia, and the large portion of the root 
 of which accurately represents the posterior root of a spinal nerve ; and of the third or 
 conmion motor nerve of the eye, of the fourth or pathetic nerve, of the sixth or exter • 
 nal motor nerve of the eye, of the portio dura of the seventh, and, lastly, of the non- 
 ganglionic portion of the fifth. All these last-named nerves are the nerves of motion ; 
 while the ganglionic portion of the fifth is the nerve of sensation. 
 
 Moreover, as the spinal nerves communicate with the ganglia of the great s3Tnpa- 
 thetic, it is of importance, for the completion of our comparison, to determine the com- 
 munications of the two cranial pairs of nerves with the same system of ganglia. Now 
 
 Dr. Marshall Hall believes to be the cause of certain instinctive motions. (" On the Reflex Functions of the 
 .Medulla Oblongata and MeduUa Spinalis."— PAtZ. Trans.. 1833.) 
 
854 NEUROLOGY. 
 
 I regard the superior cervical ganglion of the great sympathetic as common to the ivm 
 supposed cranial pairs and to the three superior cervical pairs ; in fact, the superior cer 
 vical ganglion communicates with all the branches of the posterior cranial pair, except- 
 ing the spinal accessory, viz., with the pneumogastric, the glosso-pharyngeal, and the 
 hypo-glossal ; and it also communicates with the anterior cranial pair, and more partic- 
 ularly with the fifth and sixth nerves. 
 
 As to the ophthalmic, spheno-palatine, otic, and sub-maxillary ganglia, which Arnold 
 regards as annexed to the organs of the senses, viz., the ophthalmic to the eye, the 
 spheno-palatine to the nose, the otic to the ear, and the sub-maxillary to the organ of 
 taste, and which Bichat described as the cephalic portion of the great sympathetic, [ am 
 of opinion that they are mere local ganglia, which do not form part of the general sym- 
 pathetic system : besides, the ophthalmic and the otic ganglion only can be shown to be 
 connected with the organs of any sense : it is impossible to show that the spheno-pala- 
 tine ganglion, the very existence of which as a ganglion is often doubtful, has any con- 
 nexions with the organ of smell, or that the sub-maxillary ganglion, which is much 
 more closely connected with the sub-lingual gland, has any relations with the organ of 
 taste. 
 
 THE SYMPATHETIC SYSTEM OF NERVES. 
 General Remarks. — The Cervical Portion of the Sympathetic. — The Superior Cervical Gan- 
 glion — its Superior Branch, Carotid Plexus, and Cavernous Plexus — its Anterior, Exter- 
 nal, Inferior, and Internal Branches. — The Middle Cervical Ganglion. — The Inferior Cer- 
 vical Ganglion. — The Vertebral Plexus. — The Cardiac Nerves : Right, Superior, Middle, 
 and Inferior, Left. — The Cardiac Ganglion and Plexuses. — The Thoracic Portion of the 
 Sympathetic. — The External and Internal Branches. — The Splanchnic Nerves, Great and 
 Small. — The Visceral Ganglia and Plexuses in the Abdomen, viz., the Solar Plexus and 
 Semilunar Ganglia. — The Diaphragmatic and Supra-renal ; the Coeliac, the Superior 
 Mesenteric, the Inferior Mesenteric, and the Renal, Spermatic, and Ovarian Plexuses. — 
 The Lumbar Portion of the Sympathetic. — The Communicating, External, and Internal 
 Branches. — The Lumbar Splanchnic Nerves and Visceral Plexuses in the Pelvis. — The 
 Sacral Portion of the Sympathetic. — General View of the Sympathetic System. 
 We have seen that the nerves arising from the cerebro-spinal axis are distributed to 
 the organs of the senses, to the skin, to the muscles, in short, to all the organs of ani- 
 mal life. The pneumogastric nerve alone is distributed to the organs of respiration, and 
 the upper part of the alimentary canal, viz., the pharynx, the oesophagus, and the stom- 
 ach. We shall now see that all the internal organs, which are beyond tlie influence of 
 volition and consciousness, are provided with a special nervous apparatus, which is call- 
 ed the great sympathetic, the sympathetic system, the ganglionic system, or the nervous sys- 
 tem of organic or nutritive life. 
 
 The sympathetic system consists of two long, knotted cords (/to v,fig. 268, in which 
 figure these cords are represented as if drawn outward away from their natural position) 
 extended one on each side of the vertebral column, from the first cervical to the last 
 sacral vertebra ; these cords are enlarged opposite each vertebra, to form a series of 
 ganglia, which communicate with all the spinal and cranial nerves on the one hand, and 
 give off all the visceral branches on the other. The sympathetic system consists es- 
 sentially of two distinct parts : of a central portion, formed by the two cords ; and of a 
 visceral, median, or prevertebral portion, consisting of certain plexuses and ganglia, which 
 communicate with the central cords, surround the arteries as if in sheaths, penetrate 
 the viscera with them, and establish a communication between the sympathetic cords 
 of the right and left sides. We cannot pay too much attention to the connexion be- 
 tween the ganglionic nerves and the arteries, which always serve as a support for these 
 nerves, and for which, according to some anatomists, the nerves are exclusively des- 
 tined. 
 
 Each half of the sympathetic system may be described in two ways : either as a con- 
 tinuous cord, having ganglia at intervals upon it, or as a series of ganglia or centres, 
 which may first be examined independently of each other, and around which all the fila- 
 ments that enter or emerge from them may then be arranged. 
 
 The first method, which is the more natural one, was adopted by the older anato- 
 mists, who described the sympathetic in the same way as other nerves ; according to 
 the second method, which is the one adopted by Bichat, all the ganglia, whatever situa- 
 tion they may occupy, are included in the sympathetic system ; the ophthalmic, the 
 spheno-palatine, and other cranial ganglia would, according to this view, be comprised 
 in the sympathetic system. 
 
 I believe that the better mode of description is one which associates the idea of a 
 centre with that of a cord. In fact, as the sympathetic system consists of a double line, 
 it is natural to describe it as a nervous cord, having two extremities, one cephalic, the 
 other pelvic ; and as each ganglion forms the point of termination or of origin to a great 
 
THE SUPERIOR CERVICAL GANGLION. 
 
 856 
 
 number of nervous filaments, these bodies may very properly be regarded as central 
 points. The visceral portion of the sympathetic nerves will be described with the gan- 
 glia to which they are connected. * 
 
 I shall describe in succession the cervical, the thoracic, the abdominal, and the pelvic 
 portion of the s}aTipathetic. I have already said that I do not recognise any proper ce- 
 phalic portion of this system of nerves, for the ophthalmic and the other cranial ganglia 
 seem to me to belong to a totally different class 
 
 The Cervical PortioiWf the Sympathetic System. 
 The cerw:a„ portion of the sympathetic {ft, fig- 302) has this peculiarity, that, instead 
 of being composed of as many ganglia as there are j?i^. 302. 
 
 vertebrae, it has only two or three. This may be 
 explained by supposing that the superior cervical 
 ganglion represents by itself the ganglia which are 
 wanting. It will hereafter be seen that the lumbar 
 ganglia are rather frequently fused in a similar man- 
 ner. The cervical portion of the sympathetic is 
 situated on the anterior region of the vertebral col- 
 umn, behind the internal and common carotid ar- 
 teries, the internal jugular vein, and the pneumo- 
 gastric nerve (p). It is connected to all these parts, 
 and to the praevertebral muscles, by some very 
 loose cellular tissue, a layer of fascia intervening 
 between them ; it commences by a large fusiform 
 ganglion, the superior cervical ganglion (/) ; this is 
 succeeded by a nervous cord of variable size, which 
 terminates in the middle cervical ganglion (a) when 
 that exists, but when it is absent in the inferior cer- 
 vical ganglion (t), which is continuous with the first 
 thoracic ganglion, either directly or through the 
 medium of two or three very remarkable nervous 
 loops, or frequently by both methods of connexion. 
 We shall proceed to examine the three cervical 
 ganglia. 
 
 The Superior Cervical Ganglion. 
 
 Dissection. — Remove the corresponding ramus of 
 the lower jaw ; separate the ganglion very careful- 
 ly from the pneuraogastric, glosso-pharyngeal, and 
 hypo-glossal nerves, behind which it is placed. In 
 order to trace the superior or carotid branch, make 
 an antero-posterior median section of the head ; 
 open the foramen lacerum posterius from behind, 
 in the manner indicated for exposing the pneumo- 
 gastric, and then examine the ganglion and its su- 
 perior branch from the inner side. 
 
 The superior cervical ganglion (/) is olive-shaped 
 or fusiform : it is situated in front of the second 
 and third cervical vertebrae, from which it is sep- 
 arated by the rectus capitis anticus ; it is behind 
 the internal carotid artery, and the glosso-pharyn- 
 geal, pneumogastric, and hypo-glossal nerves ; its 
 upper extremity is about ten or twelve lines distant 
 from the lower orifice of the carotid canal ; it is 
 said to have been found two inches from it. 
 
 It is larger than the other cervical ganglia {gan- 
 glion cervicale magnum), but it varies much both in 
 its length and its other dimensions ; thus, its low- 
 er extremity has been seen to reach the fourth, 
 fifth, and even the sixth cervical vertebra. Its col- 
 our is grayish, and its surface smooth : not unfre- 
 quently it is bifurcated at its lower extremity ; it 
 is rather often double. Lobstein has figured a case of this kind ; and there were also two 
 superior cervical ganglia, one placed above the other, in a case of hypertrophy of these 
 ganglia, examined and represented by myself — (Anat. Path., liv. i., pi. 3.) 
 
 These cases of a double superior cervical ganglion evidently depend on subdivision ol 
 the single ganglion usually existing. 
 
 The branches which end in or emerge from the superior cervical ganglion may be di- 
 ' vided into superior, inferior, external, internal, and anterior. I shall divide them into those 
 
856 NEUROLOGY. 
 
 which communicate with the cranial and cervical nerves, those which communicate 
 with the other cervical ganglia, and into arterial and visceral branches. The superior 
 cervical ganglioR also gives off several twigs to the muscles of the prevertebral region. 
 
 The superior cervical ganghon communicates with the cranial nerves by means of its 
 superior or carotid branch and its anterior branches. It communicates with the cervical 
 nerves by its external branches. It communicates with the other cervical ganglia by 
 its inferior branch. Its visceral and arterial Ranches are the pharyngeal, the cardiac, 
 and the branches for the external carotid, ^j^ 
 
 The Superior or Carotid Branch from the Inferior Cervical Ganglion. 
 
 The superior or carotid branch, or the branch of communication with the nerves which 
 constitute the anterior cranial pair, has been for a long time regarded as the origin of 
 the sympathetic nerve ; and as, previously to the time of Meckel, the anastomosis of 
 this carotid branch with the sixth cranial nerve, or external motor of the eye, was the 
 only one known, it was supposed that the sympathetic arose from the sixth nerve ; the 
 discovery of the vidian nerve by the elder Meckel has led to the admission of two ori- 
 gins or roots of the sympathetic, namely, one from the fifth and another from the sixth 
 cranial nerve. 
 
 Since the researches of modern anatomists, the study of the superior or carotid branch 
 of the superior cervical ganglion has become one of the most complicated points in the 
 anatomy of the nervous system. 
 
 This carotid branch appears to be a prolongation of the superior cervical ganglion ; it 
 tapers as it approaches the carotid canal, into which it enters, after having divided into 
 two branches, one of which runs on the inner side and the other on the outer side of 
 the artery. These branches communicate with each other, subdivide, and unite to form 
 the carotid plexus, and having reached the cavernous sinus, form a plexus, named the 
 cavernous plexus, which gives off the communicating branches to the sixth and fifth nerves, 
 and also the small plexuses which surround the internal carotid and its branches.* 
 
 Laumonier, and after him Lobstein and several others, described a ganghon, named 
 the carotid ganglion, in the first turn of the carotid canal ; but it is in vain to search for 
 it, unless some slight enlargements on the external and internal branches, wherevei 
 they give off or receive twigs, are to be regarded as ganglionic. + 
 
 During their course in the carotid canal, the external and internal divisions of the ca- 
 rotid portion of the sympathetic give off the following branches : 
 
 An Anastomotic Twig to the Nerve of Jacobson. — This comes off from the external 
 branch, and is very small ; it perforates the external wall of the carotid canal, enters 
 the cavity of the tympanum, and anastomoses with the nerve of Jacobson, a branch of 
 the glosso-pharyngeal. 
 
 An Anastomotic Twig to the Spheno-palatine, or McekeVs Ganglion. — This, like the pre- 
 ceding, comes from the external division of the carotid branch of the sympathetic, and 
 passes to the vidian or pterygoid branch of the superior maxillary nerve. We have al- 
 ready spoken of this twig, under the name of the carotid or deep branch of the vidian 
 nerve. Anatomists differ as to whether it should be regarded as passing from the fifth 
 nerve to the superior cervical ganglion, or from the superior cervical ganglion to the 
 fifth nerve. Arnold, on account of its grayish colour and slight consistence, regards it 
 as coming from the superior cervical ganglion, while he believes the great superficial 
 petrosal nerve, i. e., the cranial branch of the vidian, also from its colour and consist- 
 ence, to belong to the cerebro-spinal system of nerves, and to be a branch of the fifth 
 nerve. I have already said that I have never found sufficient difference between the 
 superior petrosal and carotid branches of the vidian to warrant this distinction. These 
 two nerves are, moreover, perfectly distinct from each other as far as the spheno-pala- 
 tine ganglion, in which they terminate. 
 
 It is important to observe that the two branches of the vidian nerve terminate in the 
 enlargement called the spheno-palatine, or Meckel's ganglion : the connexion of this 
 ganglion with the superior cervical ganglion has not been overlooked by those anato- 
 mists who regard the spheno-palatine enlargement as a ganglion, and who consider the 
 cranial ganglia as forming part of the sympathetic system. 
 
 Anastomotic Branches to the Sixth Nerve. — Several branches, generally three, turn round 
 the convex side of the second curve of the internal carotid, reach the outer side of that 
 artery, and anastomose, either separately, or, after having united together, with the sixth 
 or external motor oculi nerve. The nerves join at an acute angle opening backward, 
 within the cavernous sinus, and at the point where the sixth nerve crosses the carotid ; 
 as this nerve becomes flattened and widened opposite to the artery, it has been imagined 
 that it was really enlarged, and that this augmentation was due to the addition of fila- 
 ments from the sympathetic nerve ; but the enlargement is only apparent, and, notwith- 
 standing the difference in colour, I should be inclined to admit that the communicating 
 
 * The carotid branch is sometimes single, and turns spirally around the artery, being: placed at first behind, 
 then on the outer side, next on the inner, and a^ain on the outer side of the vessel. 
 
 t Arnold, whose authority upon such a subject is of great weight, has never seen this ganglion ; he very 
 properly remarks, that even those anatomists vho admit the existence of it aro not agreed as to its situation 
 
THE CAVERNOUS PLEXUS, ETC. 
 
 filaments between the sixth nerve and the carotid branches of the sympathetic are fur- 
 nished by the sixth nerve, and have a reflected course. I have seen the three commu- 
 nicating filaments between the upper part of the sympathetic and the sixth nerve form 
 a ganglifonn enlargement as they were about to join the latter ; and it was this gangli- 
 form enlargement which gave origin to the plexus surroimding the internal carotid ar- 
 tery and its branches. 
 
 The Cavernous Plexus. 
 
 The cavernous plexus, in which the two divisions of the carotid branch of the superior 
 cervical ganglion at length terminate, is situated on the inner side of the carotid artery, 
 at the point where that vessel enters the cavernous sinus. From this grayish plexus, 
 which is intermixed with small vessels (plexus nervoso-arteriosus, Walter), a consider- 
 able number of filaments proceed, some of which establish a communication between it 
 and the fifth nerve, while others surround the internal carotid, and accompany all its 
 ramifications. The following very numerous branches emerge from the cavernous 
 plexus : 
 
 Some communicating Filaments to the Third Nerve or External Motor Oculi, before the Di- 
 vision of that Nerve. — These filaments pass above the sixth nerve, to which they appear 
 to be applied.* 
 
 A Filament of Communication with the Ophthalmic Ganglion. — This arises from the an- 
 terior part of the cavernous plexus, enters the orbit between the third nerve and the oph- 
 thalmic division of the fifth, and unites sometimes with the long root of the ophthalmic 
 ganglion, which we have stated to be derived from the nasal branch of the ophthalmic, 
 and sometimes with the ophthalmic ganglion itself 
 
 This root had been described and figured by Lecat, before Bock, Ribes, and Arnold 
 recalled the attention of anatomists to it. 
 
 It follows, from the arrangement just described, that the ophthalmic ganglion has three 
 roots, two cerebro-spinal and one ganglionic. 
 
 Communicating Filaments of the Fifth Nerve. — Some of these pass to the Gasserian gan- 
 glion, and others to the ophthalmic division of the fifth.t 
 
 The Filaments which accompany the Internal Carotid Artery and its Branches. — These 
 are extremely delicate, but they are beautifully distinct in some subjects. They may 
 be followed even upon the branches of the internal carotid. 
 
 Anatomists admit the existence of a plexus for the ophthalmic artery, and for each of 
 its subdivisions. It is even supposed that there is one for the arteria centralis retinae. t 
 
 Several authors have described a certain number of filaments proceeding from the 
 cavernous plexus to the pituitary body (filets sus-sphenoidaux, Chaussier). I have nev- 
 er been fortunate enough to discover them, nor yet the ganglion (the ganghon of Ribes) 
 which is said to exist upon the anterior communicating artery of the brain, and which 
 is found at the point of junction of the right and left trunks of the sympathetic. 
 
 It follows, from what has been stated, that the superior cervical ganglion, by means 
 of its upper or carotid branch, communicates with most of the nerves of the anterior cra- 
 nial pair ; namely, with the fifth nerve, by means of the Gasserian ganglion, of the oph- 
 thalmic division of the fifth, and of the ophthalmic ganglion, either directly or indirectly ; 
 also by means of the superior maxillary division of this nerve, through the intervention of 
 the spheno-palatine ganglion ; secondly, with the third nerve ; and, lastly, with the sixth. 
 
 The Anterior Branches from the Superior Cervical Ganglion. 
 
 The anterior branches of the superior cervical ganglion establish a communication with 
 the different nerves of the posterior cranial pair, excepting the spinal accessory nerve, 
 which does not appear to have any direct communication with it. 
 
 The glosso-pharyngeal and pneumogastric nerves communicate with the superioi 
 cervical ganglion at two different points, viz., at their ganglia, and by their branches. 
 
 The communication of the superior cervical ganglion with the ganglia of the glosso-pha 
 ryngeal and pneumogastric nerves has been pointed out by Arnold ; it is difficult to dem 
 onstrate it through the dense tissue which surrounds these ganglia. 
 
 On the contrary, it is extremely easy to demonstrate the communications of the glos- 
 so-pharyngeal nerve and the plexiform cord of the pneumogastric with the superior cer- 
 vical ganglion. I have already said (see Pneumogastric Nerve) that in one case I found 
 the pneumogastric so closely applied to the whole length of the superior cervical gangli- 
 on, that it was impossible to separate them. The communication of the superior cervi- 
 cal ganglion with the hypo-glossal is quite as evident as the preceding. 
 
 The filaments of communication with the nerves forming the posterior cranial pair do 
 not always proceed from the superior cervical ganglion itself, but sometimes from its ca. 
 rotid branch. 
 
 * I have never seen the communication between the superior cervical ganglion and the facial nerve noticed 
 by some anatomists. 
 
 t I may here again notice, that in two subjects I have seen a twig from the spheno-palatine ganglion join 
 the communicating branches between the sixth nen-e and the sympathetic. 
 
 t M. Ribes, Miimoires de la Societfi Medicale d'EmuIatiun, t. vii. 
 
 .5Q 
 
NEUROLOGY. 
 
 The External Branch from the Superior Cervical Ganglion 
 
 The external branches of the superior cervical ganglion establish a communicatton be- 
 tween it and the first, second, and third cervical nerves ; they are large, have a gray colour, 
 and a ganglionic structure ; we may regard them as true prolongations of the superior 
 cervical ganglion ; the principal of them enter the angle of bifurcation of the second cer 
 vical nerve, into its ascending and descending branches ; the others, which are very 
 small, join the first cervical nerve. They constitute a true ganglionic plexus, and often 
 form two distinct groups. 
 
 Frequently the superior cervical ganglion communicates only with the first and sec- 
 ond cervical nerves. At other times it also communicates with the third and fourth 
 nerves by means of a long and very oblique branch. In one case it communicated di- 
 rectly with the phrenic nerve. 
 
 The Inferior Branch from the Superior Cervical Ganglion. 
 
 The inferior branch from the superior cervical ganglion, or the branch of communica 
 tion with the middle cervical ganglion, is a white cord, resembling a spinal nerve, ex- 
 cepting in a few cases, in which it appears to be a prolongation of the tissue of the ganglion 
 itself: when the lower extremity of the superior cervical ganglion is divided into two 
 parts, its inferior branch arises from the external division. It varies much in size in 
 different subjects : it descends vertically in front of the spinal column, behind the com- 
 mon carotid, the internal jugular vein, and the pnemnogastric nerve, to which it is uni- 
 ted by a very loose cellular tissue. 
 
 Having reached the inferior thyroid artery, the cord of the sympathetic passes behind 
 that vessel, and enters the middle cervical ganglion, when that exists ; but when it is ab- 
 sent, the cord continues on to join the inferior cervical ganglion. As it descends, it most 
 commonly receives some twigs from the third and fourth cervical nerves, which twigs we 
 have already said occasionally enter the superior cervical ganglion. At its origin, it 
 gives off on the inner side two filaments, which join the superior cardiac nerve, and in- 
 crease its size ; and an anastomotic twig to the external laryngeal nerve, a branch of 
 the superior laryngeal. Not unfrequently the superior cardiac nerve arises entirely from 
 the communicating branch between the superior and middle cervical ganglia, that branch 
 appearing to bifurcate. 
 
 The communication between the superior and middle cervical ganglia is subject to 
 much variety. I have seen a small ganglion upon it opposite to the inferior thyroid ar- 
 tery ; from this ganglion, which rested upon the artery, and which might be regarded as 
 the vestige of a middle cervical ganglion; two cords proceeded, an anterior, which join- 
 ed the cardiac nerve, and a posterior, which ended in the inferior cervical ganglion : 
 both of these had a gangliform structure. The cord of the sympathetic is not uncom- 
 monly found enlarged at intervals into ganglionic nodules. 
 
 The Internal Branches, or Carotid and Visceral Branches. 
 
 The internal branches from the superior cervical ganglion are divided into those which 
 accompany the external carotid and its ramifications, and those which are distributed to 
 the viscera. 
 
 The Carotid Branches. — It has been stated that from the upper extremity of the supe- 
 rior cervical ganglion certain branches are given off, which surround the internal carot- 
 id, and are prolonged upon its ramifications. 
 
 From the inner border of the same ganglion other branches proceed, which embrace 
 the external carotid and the ramifications of that vessel. 
 
 These nerves are of a gray colour (subruji), of a soft texture (nervi molles et pene mu- 
 cosi, Scarpa), and of a knotted and gangliform structure (rami gangliformes, Neubauer) ; 
 they come off from the ganglion opposite to the origin of the facial artery ; they pass in- 
 ward behind the external and internal carotids, and form a sort of gray plexus, which ex- 
 tends as far as the origin of the internal and external carotid ;* they turn like a loop 
 around the former of these vessels, and anastomose with the carotid filaments from the 
 glosso-phaiyngeal, and from the pharyngeal and superior laryngeal branches of the pneu- 
 mogastric. None of the branches from this plexus are prolonged upon the conmuon ca- 
 rotid ; they all pass upon the external carotid and its different ramifications, forming as 
 many plexuses as there are vessels, and are distributed with those vessels to the neck 
 and the face. Thus, there is a thyroid plexus, which surrounds the superior thyroid ar- 
 tery, and may be traced into the thjToid body ; a lingual plexus, which enters the sub- 
 stance of the tongue, and is supposed to anastomose with the lingual branch of the infe- 
 rior maxillary division of the fifth, and even with the hypo-glossal nerve ; and & facial 
 plexus, which is supposed to anastomose with the facial nerve. Anatomists have par- 
 ticularly directed their attention to the branches which enter the sub-maxillary gland ; 
 some imagining, and others regarding it as certain, that these branches communicate 
 with the sub-maxillaiy ganglion. I have never been fortunate enough to discover this 
 communication. 
 
 * At this division there is frequently a gangliform enlargement, which Arnold proposes to call the inter-ca- 
 rotid ganglion. 
 
THE MIDDLE AND INFERIOR CERVICAL GANGLIA. 8S9 
 
 There is, moreover, a pharyngeal plexus, an occipital plexus, and an auricular plexus : 
 the elder Meckel* has even described an anastomosis between the facial nerve and the 
 sympathetic filament which accompanies the posterior auricular artery. Lastly, the 
 temporal artery, and the internal maxillary artery and its divisions, are also surrounded 
 (hederae ad modum, Scarpa) by small nervous plexuses ; these plexuses are sometimes 
 so well developed, that the elder Meckel states that the arteries of the face have larger 
 nervous plexuses than any others in the body. These plexuses appear to me to be pe- 
 culiarly remarkable for containing a mixture of white fibres and nervi molles, which 
 proves their double origin. 
 
 All these plexuses present gangliform enlargements at various points, as is shown in 
 the splendid plate in Scarpa's work.t This author has figured, after Andersh, a gangli- 
 on which he believes to be constant at the division of the external carotid and temporal 
 arteries. A twig from the facial nerve terminates in this ganghon.f 
 
 The Visceral Branches. — All these come off from the inner side of the ganglion, and 
 divide into pharyngeal, laryngeal, and cardiac branches. 
 
 The pharyngeal branches are certain thick ganglionic cords which arise from the upper 
 and inner part of the superior cervical ganglion, pass transversely inward, and combine 
 with the pharyngeal branches of the glosso-pharyngeal and pneumogastric nerves to 
 form one of the most remarkable plexuses in the body, which is distributed to the pha- 
 rynx. To this plexus must be relterred all those highly important nervous phenomena 
 which are manifested in connexion with the pharynx, more particularly the sensation of 
 thirst. 
 
 • The laryngeal branches unite with the superior laryngeal nerve and its divisions. In a 
 case in which the external laryngeal nerve arose separately from the pneumogastric and 
 not from the superior laryngeal, it had as many filaments of origin from the superior 
 cervical ganglion as from the pneumogastric itself 
 
 The cardiac branches form the superior cardiac nerve, to which I shall recur after hav 
 ing described the middle and inferior cervical ganglia. 
 
 The Middle Cervical Ganglion. 
 
 The middle cervical ganglion {a, Jig. 302) is wanting in a great number of subjects, and 
 then the branches usually given off from and received by it are given off and received 
 by the cords which connect the superior and inferior cervical ganglia, or by the inferior 
 cervical ganglion itself The middle cervical ganglion is sometimes double ; at othe'' 
 times it is in quite a rudimentary state. 
 
 It is situated on a level with the fifth or sixth cervical vertebra, in front of the inferior 
 thyroid artery, opposite to the first curve of that vessel, and sometimes behind it ; its 
 relation to this artery, which is very nearly constant, induced Haller to name it the thy- 
 roid ganglion : however, I have frequently seen it eight lines above that artery. Its 
 form and size are extremely variable, not only in different subjects, but even upon oppo- 
 site sides of the same subject.' Sometimes it is a simple gangliform enlargement. 
 Scarpa has figured a middle cervical ganglion almost as large as the superior, and, like 
 it, olive-shaped. I have never seen it as large as this.^ 
 
 The middle cervical ganglion, when it exists, receives, 
 
 Above, the cord which communicates with the superior cervical ganglion ; below, the 
 cord of communication, often multiple, with the inferior cervical ganglion ; on the out 
 side, three branches, derived from the third, fourth, and fifth cervical nerves : not un- 
 frequently the communicating branch from the fourth cervical nerve belongs to the 
 phrenic ; on the inside, the middle cardiac nerve, or great cardiac of Scarpa, which I shall 
 presently describe. 
 
 The size of the middle cervical ganglion has always appeared to me to be proportioned 
 to that of its filaments of communication with the cervical nerves. 
 
 The Inferior Cervical Ganglion. 
 Neubauer has given an excellent description of the inferior cervical ganglion, under 
 the name of the first thoracic ganglion, rather an appropriate title for it, because it is fre- 
 quently continuous with the first thoracic ganglion (as at i, fig. 302) ; and, secondly, be- 
 cause it is situated in front of the transverse process of the seventh cervical vertebra 
 and of the head of the first rib. This ganglion is constant ; it is deeply seated behind 
 the origin of the vertebral artery, by which it is completely concealed. Ii 
 
 * M6moires de I'Acad. de Berlin, 1752. t Tabulae Neurologicae, tab. iii., 1794. 
 
 T Arnold has described and figured a twig from the plexus which surrounds the middle meningeal or spheno- 
 spinous artery, and which, according to this laborious inquirer, terminates in the otic ganglion ; he also de 
 scribes some nervous twigs passing from the plexus of the ascending palatine artery to the sub-maxillary 
 ganglion. In this way he establishes a connexion between the sympathetic system and these two cranial gan- 
 glia. I have devoted great care to this subject, but have never been able to make out these communicating 
 filaments, even though all the difficult dissections have been made upon specimens previously macerated in 
 diluted nitric acid. 
 
 1) I believe that it is incorrect to regard as a middle cervical ganglion those ganglionic nodules, without 
 either afferent or efferent filaments, which are rather frequently found at various points on the trunk of the 
 sympathetic. 
 
 H It is not rare to see the inferior cervical ganglion describe around the vertebral artery a half ring, which 
 is completed in front by a gray cord extended from one end of the ganglion to the other. 
 
860 NEUROLOGY. 
 
 It is of a semilunar shape, its concave border being turned upward and its convex one 
 downward ; at its internal extremity it receives the trunk of the sympathetic ; at its ex- 
 ternal extremity it receives a large nerve which accompanies the vertebral artery, and 
 which may be called the vertebral nerve ; at the same extremity it also receives some 
 communicating branches from the fifth, sixth, and seventh cervical nerves, and often 
 from the first dorsal. Several branches proceed from its convex border, which is turned 
 downward ; some pass in front of and others behind the sub-clavian artery, which they 
 embrace like loops. Most of these inferior branches are the communicating branches 
 between the inferior cervical and the superior thoracic ganglion, and they exist even 
 when the two ganglia are directly continuous with each other. One of the branches 
 sometimes joins the recurrent laryngeal branch of the pneumogastric ; the most remark- 
 able of the inferior branches constitutes the inferior cardiac nerve, which is rather fre- 
 quently derived from the superior thoracic ganglion. 
 
 To complete the description of the cervical portion of the sympathetic, we have now 
 only to speak of the vertebral nerve and of the cardiac nerves. 
 
 The Vertebral Plexus. 
 The vertebral plexus or vertebral nerve occupies the canal which is formed for the verte- 
 bral artery in the transverse processes. It is generally said that this nerve arises from 
 the inferior cervical ganglion ; that it traverses the entire length of the canal formed for 
 the vertebral artery, enters the cranium with that vessel, and then unites with its fel- 
 low of the opposite side to form the basilar plexus, which divides and subdivides around 
 the terminal ramifications of the basilar artery, like the plexuses which are formed 
 around the internal carotid ; but such is not a correct description of the nerve. It ap- 
 pears to me to be formed by the junction of filaments derived from the third, fourth, and 
 fifth cervical nerves, gradually to increase in size from above downward as it receives 
 new filaments, then to pass behind the artery, to emerge from the canal also behind the 
 vessel, and, finally, to enter the inferior cervical ganglion. I conceive that this branch 
 is intended to establish a communication between the third, fourth, and fifth cervical 
 nerves and the inferior cervical ganglion. I have never found upon these branches the 
 swellings or gangli which, according to M. Blainville's ingenious idea, might be intend- 
 ed to supply the place of the cervical sympathetic ganglia, and to destroy the appear- 
 ance of irregularity which exists in the cervical region in this respect. 
 
 The Cardiac Jferves. 
 
 Dissection. — This comprises the dissection of the cardiac nerves, from their origin to 
 the point where the aorta and pulmonary artery cross each other ; and from that point 
 to the extreme divisions of the nerves. For this purpose, after having previously ex- 
 posed the cervical ganglia and the cardiac nerves, the preparation should be macerated 
 in diluted nitric acid ; all the internal nerves which proceed from the ganglion should 
 then be carefully dissected, so as to preserve their relations with the cardiac branches 
 of the pneumogastric and recurrent nerves ; we must then examine the nerves which 
 pass in front of the aorta, those which run between that vessel and the pulmonary ar- 
 tery and trachea, and, lastly, those which pass behind the pulmonary artery ; we should 
 study, at the same time, their relations with the anterior and posterior cardiac plexuses. 
 
 The cardiac nerves, or nerves of the heart, which are distinguished into the right and 
 the left,* arise essentially from the cervical ganglia. These ganglionic nerves are then 
 joined by several branches from the pneumogastric ; they all converge upon the origin 
 of the aorta and pulmonary artery to form the cardiac plexuses, which give off the right 
 and left coronari/ plexuses ; these latter plexuses surround the coronary arteries, and their 
 branches are scattered over the surface of the heart, but do not enter its substance un- 
 til they have advanced a considerable distance beneath the serous membrane by which 
 the heart is covered. 
 
 Such is the most general idea that can be given of the cardiac nerves and plexuses, 
 which afford one example of the most remarkable of the median anastomoses. Scarpa 
 first described and figured them correctly in his plates, which will always be models for 
 anatomical drawings. No nerves present so many varieties, in number, size, and ori- 
 gin, as the cardiac nerves ; and on this subject especially, the want of a work upon ana- 
 tomical varieties is especicilly felt. For my part, I declare that I have never found the 
 cardiac nerves in my dissections as they are represented in Scarpa's magnificent plates, 
 
 * The history of flie nerves of the heart is singular. The ancient philosophers, with Aristotle, influenced 
 by certain preconceiited ideas, staled that the heart was the source of all the nerves in the body. Galen re- 
 futed this opinion, and J^dmitted that the heart had but one very small nerve, which descended from the brain. 
 Vesalius considered that this slender nerve came from the recurrent, and represented it in a figure. Fallo 
 pius first described the nerves of the heart, and says that he showed his audience " insignem nervorum plexum 
 » quo ahundans copia nervosa materia totam cordis basim complexatur, pergue ipsam plures propagines parvo- 
 rum nervorum dispergit." Behrends, in 1792, defended a thesis in which he endeavoured to demonstrate that 
 the heart has no nerves, cornervis carere. Such was the amount of knowledge on this subject when, in 1794, 
 Scarpa published his splendid work, and settled the state of science on this point. — (.Tabulae Neurohgicee ad 
 Illustrandam Anatomiam Cardiacorum Nervorum, Noni Nervorum Cerebri, Glosso-pharyngax et Pharynga:i ex 
 Octavo Cerebri.) 
 
THE RIGHT CARDIAC NERVES. Wfl 
 
 which have served as the type for all descriptions. I have minutely described the cardiac 
 nerves in eight different subjects ; these eight descriptions present very great differen- 
 ces, at least, until one arrives at the account of the cardiac plexuses ; the ultimate dis- 
 tribution of the nerves of the heart appeared to be the same in all these subjects. 
 
 All the cardiac nerves are gray, but they are not all soft, as declared by Scarpa, who 
 called them nervi molles. Sometimes the right, and sometimes the left cardiac nerves, 
 are the larger ; the nerves of the two sides are inversely proportioned to each other in 
 this respect, and there is evidently a mutual dependance between them. In one case, in 
 which tlie middle and inferior cardiac nerves of the right side were wanting, and the 
 superior cardiac nerve very small, their places were supplied by some large branches 
 from the right recurrent nerve, and by the left cardiac nerves, which were largely de- 
 veloped. 
 
 Anatomists follow Scarpa in describing three cardiac nerves on each side : a superior, 
 named by him the superficial cardiac nerve, which is derived from the superior cervical 
 ganglion ; a middle, called by him the great or deep cardiac nerve, which arises from the 
 middle cervical ganglion ; and an inferior, or small cardiac nerve, proceeding from the 
 inferior cervical ganglion. Although this is the usual arrangement, it is often impossible 
 to distinguish three nerves, in consequence of the anatomical varieties which I have al- 
 ready mentioned. There is frequently no middle cardiac nerve properly so called ; at 
 other times there is no inferior cardiac nerve, or, rather, they are both in a rudimentary 
 state ; lastly, the superior cardiac nerve, if not entirely wanting, may be extremely small, 
 and may join the middle cardiac nerve. Sometimes all the cardiac nerves of one side 
 unite into a single trunk, or else into a plexus situated behind the sub-clavian artery, 
 upon the side of the trachea ; the recurrent nerve assists in forming this plexus, from 
 which three, four, or more branches are given off to be distributed to the heart in the 
 usual manner. One of the most important points in the history of the cardiac nerves is 
 their sort of fusion with the pneumogastric, which is so intimate that the cardiac branch- 
 es of the pneumogastric, and those which come from the ganglia, form a single system. 
 There is a similar fusion between the superior, middle, and inferior cardiac nerVes of 
 each side, and between the nerves of the two sides. 
 
 The recurrent nerve, in particular, appears sometimae to be distributed equally to the 
 larynx and the heart, so large and numerous are the cardiac branches given off from it ; 
 it will hereafter be seen that there is an equally intimate connexion between the pneu- 
 mogastric nerve and the solar plexus. 
 
 I shall first describe in detail the right cardiac nerves, and shall then briefly point out 
 the differences between them and the left cardiac nerves. 
 
 The Right Cardiac Nerves. 
 
 The Superior Cardiac Nerve. — Its origin is very variable. Most commonly, it arises 
 from the internal division of the bifurcated lower extremity of the superior cervical gan- 
 glion, the cord of communication between the superior and the next cervical ganglion 
 forming the external division. At other times it arises from the communicating cord. 
 In a great number of cases it has several origins, being formed by two or three very 
 small filaments, which come from the inner side of the superior cervical ganglion ; by a 
 branch, often a large one, from the cord of communication ; and by two filaments from 
 the pneumogastric nerve. In one of these latter cases the cardiac branch from the cord 
 of conmiunication presented a very distinct ganglion. 
 
 Whatever may be its origin, the superior cardiac nerve passes obliquely doTvnward and 
 inward, behind the common carotid, from which it is separated by a very thin layer of 
 fascia, so that it is almost impossible to include it in applying a ligature to that artery ; 
 it runs along the trachea, very often receives a branch from the trunk of the sympathet- 
 ic, and crosses in front of the inferior thyroid artery, or sometimes divides into two branch- 
 es, one of which, the anterior, passes in front of the artery, while the posterior joins the 
 recurrent nerve.* At the lower part of the neck the superior cardiac nerve runs along 
 the recurrent laryngeal nerve, with which it may be confounded ; it enters the thorax, 
 passing behind and sometimes in front of the sub-clavian artery,t runs along the brachio- 
 cephalic trunk, gains the back of the arch of the aorta, gives off a certain number of fila- 
 ments, which pass in front of that part of the vessel, then runs obliquely downward and 
 to the lelt between the arch of the aorta and the trachea, anastomoses very fi-equently 
 with the middle and inferior cardiac nerves and with the branches of the recurrent, and 
 divides into two sets of filaments ; some of these pass between the aorta and the pul- 
 monary artery, and others between the right puhnonary trunk and the trachea ; they both 
 
 * The trunk of the sympathetic, havin? reached the inferior thyroid artery, sometimes divides into two 
 branches, one of which passes in front of that artery, to join the superior cardiac nerve, while the other passes 
 behind it to the inferior cervical ganglion ; not nnfrequently the superior OM-diac nerve presents a ganglionic 
 enlargement, which occupies the whole or a part of the thickness of the nerve. 
 
 t The superior cardiac nerve often bifurcates so as to embrace the sub-clavian artery in a complete ring. 
 At other times the superior cardiac nerve passes liehind the sub-clavian artery, and the cardiac branch of the 
 pneumogastric in front of it, so as to form beneath the sub-clavian an anastomotic loop, which lies to the inner 
 side of the one formed by the recurrent nerve. Most commonly the cardiac branch of the pneumogastric anas 
 tomoses with the superior cardiac nerve, between the arch of the aorta and the trachea. 
 
862 NEUROLOGY. 
 
 anastomose with the left cardiac nerves, and are arranged as we shall soon describe. In 
 some rare cases, the right superior cardiac nerve goes directly to the cardiac plexus, 
 without anastomosing with the middle and inferior cardiac nerves. 
 
 During its course along the neck, the right superior cardiac nerve receives the small 
 superior cardiac branches of the pneumogastric, and gives off several filaments, some to 
 the pharynx, others to the trachea and the thyroid body, while several assist in forming 
 the plexus of the inferior thyroid artery ; it often gives off three or four branches which 
 anastomose with the recurrent nerve. 
 
 In the thorax, the superior cardiac nerve is joined by the cardiac branch given off by 
 the pneumogastric in the lower part of the neck, and which is sometimes of very consid- 
 erable size, and evidently re-enforces the cardiac nerve ; this branch of the pneumogas- 
 tric sometimes terminates directly in the cardiac plexus. 
 
 The Middle Cardiac Nerve. — This nerve arises from the middle cervical ganglion, or, 
 when that is absent, from the trunk of the sympathetic, at a variable distance from the 
 inferior cervical ganglion. It is rather frequently the largest of the cardiac nerves, and 
 has, therefore, been called by Scarpa the great cardiac nerve {magnus, jirofundus). At 
 other times it is in a rudimentary state, and is replaced either by the superior or the in- 
 ferior cardiac nerve, or by branches from the recurrent : it frequently divides into sev- 
 eral twigs, between which the sub-clavian passes ; it almost always anastomoses with the 
 superior and inferior cardiac nerves of the same side, runs along the recurrent nerve, for 
 which it might be mistaken, and with which it is always connected, and then terminates 
 in the cardiac plexus. 
 
 The Inferior Cardiac Nerve. — This is generally smaller {cardiacus minor) than the pre- 
 ceding nerve, though it is sometimes larger ; it usually arises from the inferior cervical 
 ganglion, but rather fequently from the first thoracic ; it accompanies the middle cardi- 
 ac nerve, anastomoses with that nerve, and, like it, descends vertically in front of the 
 trachea, and terminates in the cardiac plexus. 
 
 The connexion of the middle and inferior cardiac nerves with the recurrent nerve de- 
 mands especial attention. Sometimes the recurrent sends off certain large branches 
 which join the cardiac nerves, and form their principal origin. I have seen the middle 
 and inferior cardiac nerves united together, crossing over the recurrent nerve at right 
 angles, and adhering intimately to it without presenting that admixture of filaments which 
 constitutes an anastomosis.* 
 
 The Left Cardiac Nerves. 
 
 The peculiarities of the left cardiac nerves maybe stated in a few words :t in the neck, 
 they are situated in front of the oesophagus, on account of the position of that canal. 
 The connexions between the cardiac nerves and the recurrent on the left side appear to 
 me more numerous than those on the right. In one case, the superior and inferior car- 
 diac nerves gave off a series of four rather large filaments, which ran along the recur- 
 rent, left that nerve opposite to its point of reflection, and then terminated in the usual 
 manner. I ascertained that, in this case, the two nerves were merely in contact, and 
 did not anastomose. 
 
 In the thorax, the superior and middle cardiac nerves of the left side descend between 
 the carotid and sub-clavian, and then run upon the concavity of the arch of the aorta ; 
 the inferior cardiac nerve, which is the largest of all the cardiac nerves in a subject 
 which I have now before me, passes to the left of the trunk of the pulmonary artery, 
 turns round its back part, and embraces it in a loop, so as to enter that portion of the 
 cardiac plexus which is situated between the aorta and the right division of the pulmo- 
 nary artery. Lastly, on the left side, more commonly than on the right, the anterior 
 pulmonary plexus sends off some filaments to this same part of the cardiac plexus. 
 
 The Cardiac Ganglion and Plexuses. 
 
 We have seen that the cardiac nerves of the same side anastomose with eacn other 
 on the sides or in front of the trachea. Besides this, the right cardiac nerves anasto- 
 mose with the left upon the concavity of the arch of the aorta ; also in front of the tra- 
 chea, above the right pulmonary artery ; and, lastly, in the anterior and posterior coro- 
 nary plexuses. 
 
 Wrisberg was the first to describe a ganglion in the situation of the first-named anas- 
 tomosis, that is to say, upon the concavity of the arch of the aorta, between that vessel 
 and the pulmonary artery, to the right of the remains of the ductus arteriosus. This 
 ganglion, which is by no means constant, is named the cardiac ganglion ; it is joined [so 
 as to form the superficial cardiac plexus] by the superior cardiac nerve of the right side, 
 
 * It is especially in these anastomoses between the cardiac and recurrent nerves that I have been able, 
 from the different aspect of the iiljuaents of each, to ascertain that the anastomoses of nerves are often mere- 
 ly apparent, and consist of a simple^uxtaposition of two nerves without any communication of their component 
 fasciculi, which can be traced uninterruptedly from their entrance to their emergence. The same observa- 
 tion applies also to some of the anastomoses between nerves of the same kind. 
 
 t In one subject, three filaments arose from the left superior cervical ganglion, and united in a small gan- 
 glionic nodule, which also received a twig from the laryngeal nerve. This ganglionic nodule gave off several 
 pharyngeal twigs, and also the superior cardiac nerve 
 
THORACIC PORTION OP THE SYMPATHETIC SYSTEM. 863 
 
 by the same nerve of the left side, and sometimes also by the right and left cardiac 
 branches given off from the pneumogastric nerves in the lower part of the neck. 
 
 The second anastomosis, or that which takes place in front of the trachea, above the 
 right pulmonary artery, and behind the arch of the aorta, has been known, since the time 
 of Haller, as thJB great cardiac plexus (magnus, profundus plexus cardiacus, Scarpa). A 
 ganglionic enlargement is not unfrequently found at the junction of the principal branch- 
 es. This great cardiac plexus is chiefly formed by the middle and inferior cardiac nerves 
 of both sides : [it also receives part of the right superficial nerves.] Lastly, all the car- 
 diac nerves end in the third set of anastomoses, namely, those upon the anterior and 
 posterior coronary arteries around the root of the aorta. 
 
 Great as the variety may be in the course and size of the cardiac nerves up to the 
 origin of the great vessels from the heart, there is as constant a uniformity in their ar- 
 rangement around those vessels, and in their ultimate distribution to the heart. 
 
 Upon the origin of the great vessels, the cardiac nerves are arranged in three layers 
 or sets. 
 
 The superficial layer of nerves is the smallest ; it occupies the anterior surface of the 
 arch of the aorta, and especially its right side ; the nerves are visible without any dis- 
 section through the transparent pericardium ; they all pass {v) to the anterior coronary 
 artery, to the right side of the infundibulum of the right ventricle. In this superficial 
 layer, the superficial cardiac plexus, may be included the ganglion of Wrisberg, when it 
 exists, and its several branches, which in a great measure assist in forming the anterior 
 coronary plexus. 
 
 The middle layer of nerves is composed of two very distinct parts, viz., of the great or 
 deep cardiac plexus of Haller, which is situated between the trachea and the arch of the 
 aorta, above the right pulmonary artery ; and of a much smaller part, situated below the 
 great cardiac plexus, from which it is derived, and between the right pulmonary artery 
 and the arch of the aorta. In order to obtain a good view of this layer, the arch of the 
 aorta must be cut through. 
 
 The deep layer of nerves is situated between the right pulmonary artery and the bifur- 
 cation of the trachea. The trunk of the pulmonary artery must be divided in order to 
 expose it. 
 
 The Anterior and Posterior Coronary Plexuses. — ^The whole of the superficial cardiac 
 plexus or superficial layer of nerves ends in the anterior coronary plexus (») which sur- 
 rounds the right coronary artery. The middle and posterior layers unite below the right 
 pulmonary artery, in front of the auricles, to form a plexus, which might more properly 
 be named the great or deep cardiac plexus than the interlacement so called by Haller. 
 From this plexus, into which the left inferior cardiac nerve enters directly, the follow- 
 ing branches proceed : anterior auricular branches, which are very numerous ; certain 
 branches which pass between the aorta and the pulmonary artery to gain the right side 
 of the infundibulum, and join the anterior coronary plexus, which, as we have seen al- 
 ready, is derived from the superficial cardiac plexus ; lastly, the branches for the poste- 
 rior coronary plexus, which surrounds the origin of the left coronary artery, and divides, 
 like that vessel, into two secondary plexuses, one of which runs round the left auriculo- 
 ventricular furrow, while the other (»') enters the anterior ventricular furrow. 
 
 The nervous filaments from these plexuses soon leave the ramifications of the arter- 
 ies ; they proceed separately ; they are all equally small, and can be seen without any 
 dissection, like white lines, extending from the base towards the apex of the heart. 
 They all belong to the ventricular portion of the heart ; a few of them, however, ascend 
 on the posterior surface of the auricles, which are much more abundantly supplied upon 
 their anterior surface. 
 
 The cardiac nerves are not entirely distributed to the heart ; several of them are lost 
 in the coats of the aorta, some join the anterior pulmonary plexus, and some ramify in 
 the pericardium. 
 
 The Thoracic Portion of the Sympathetic System. 
 In the thorax, the trunk of the sympathetic (i t, fig. 302) consists, on each side, of a 
 grayish cord, having as many nodules or ganglia upon it as there are vertebrae. This 
 cord is situated, not in front of the dorsal vertebrae, but in front of the heads of the ribs, 
 to which the gangUa for the most part correspond : the two superior thoracic ganglia 
 are the largest, and are almost always united ; the succeeding ganglia are almost of 
 equal size, the twelfth being next in size to the first and second. The ganglionic struc- 
 ture is observed throughout the whole extent of this part of the sympathetic, so that 
 the cords of communication between the ganglia may be said to be merely prolongations 
 of the ganglia. In some subjects the ganglia cannot be distinguished from the portions 
 of the sympathetic trunk above and below them, except by the branches which enter 
 and converge from those points ; it would, therefore, be a serious anatomical error to 
 regard the portions of the trunk between the ganglia as mere filaments of communica- 
 tion. In some subjects the cords between the ganglia are divided into two or three fila- 
 ments. The varieties observed in the number of the thoracic ganglia are rather appa- 
 
864 NEUROLOGY. 
 
 rent than real : tliey depend, some upon fusion of the first thoracic ganglion with the 
 inferior cervical ganglion, or of the first and second thoracic ganglia ; others upon fusion 
 of two central ganglia, or upon that, which is more common, of the last thoracic with 
 the first lumbar ganglion ; upon a transposition of the last thoracic ganglion, which is 
 then found upon the first lumbar vertebra ; and, lastly, upon the two inferior thoracic 
 ganglia being situated in the last intercostal space. Besides this, the three lowest tho- 
 -acic ganglia are subject to much variety, both in situation and in shape ; and the same 
 may be said of the mode of connexion between the twelfth thoracic and the first lumbar 
 ganglion. 
 
 The thoracic portion of the sympathetic lies beneath the pleura and the very thin 
 fibrous layer by which that membrane is strengthened. It can be distinctly seen with- 
 out any dissection, in consequence of the transparency of these layers. The intercos- 
 tal arteries and veins pass behind it ; on the right side, the vena azygos runs along it. 
 
 The thoracic portion of the sympathetic gives off external branches, or branches of 
 communication with the dorsal nerves ; and the internal branches, which are intended 
 for the aorta and the abdominal viscera. 
 
 The External or Spinal Branches. 
 
 There are at least two spinal branches from each ganglion, one superficial and larger, 
 which is connected to the outer angle of the ganglion ; the other deep and smaller, 
 which is attached to its posterior surface : there is sometimes a third filament of com- 
 munication. Not unfrequently these branches unite into a single trunk, before reaching 
 the ganglion. 
 
 I regard these anastomotic branches (e e), between the spinal nerves and the ganglia 
 of the sympathetic, not as branches furnished by the ganglia to the spinal nerves, nor 
 simply as means of communication between one and the other, but rather as branches 
 of origin of the sympathetic : this, indeed, is clearly demonstrated by the arrangement 
 of these spinal branches of the sympathetic, which are always proportioned to the size 
 of the ganglia from which they arise. In general, each ganglion communicates only 
 with the corresponding spinal nerve ; not unfrequently, however, a ganglion receives a 
 twig from the intercostal nerve immediately below it.* 
 
 The branches of conununication from the dorsal nerves to the thoracic ganglia of the 
 sympathetic are horizontal, or, rather, they are inclined obliquely downward and inward, 
 excepting those which ascend to the first thoracic ganglion, and those which descend to 
 join the last thoracic ganglion. These branches are white, like the nerves of the cere- 
 bro-spinal system, and not gray, like the ganglionic nerves. On examining their ulti- 
 mate distribution in the sympathetic ganglia, and their connexions with the dorsal and 
 intercostal nerves, after the parts have been macerated, first in diluted nitric acid and 
 then in water, it is seen that these branches are evidently reflected funiculi of the spi- 
 nal nerves ; and that the nerves, immediately after having given off these branches, are 
 proportionally diminished in size ; that, having reached the ganglia, the communicating 
 branches divide into filaments, of which some ascend, and may be traced upon the trunk 
 of the sympathetic above the ganglion, and appear to be continuous with the descending 
 filaments derived from the spinal nerve above, while the others descend to pass upon the 
 portion of the sympathetic trunk below the ganglion ; and, lastly, that these white fila- 
 ments run upon the surface of the sympathetic, and contrast with the gray colour of the 
 central portion of that nerve. 
 
 The Internal, or Aortic and Splanchnic Branches. 
 
 The internal branches of the first five or six thoracic ganglia are exclusively intended fo~ 
 the aorta ; some of them appear to enter the pulmonary plexus. 
 
 Some of the internal branches of the last six thoracic ganglia are intended for the aorta, 
 and the remainder, which are the principal, unite to form the splanchnic nerves or nerves 
 of the abdominal viscera. I have never seen any of them pass to the oesophagus. 
 
 The Aortic Branches. — The aortic branches consist of very small filaments, of which 
 two or three proceed from each ganglion. They accompany the intercostal arteries, 
 around which they form small plexuses. These filaments are much longer on the right 
 than on the left side, on account of the position of the aorta ; they pass, some in front 
 and others behind that vessel, upon which it soon becomes impossible to follow them. 
 The aortic branch from the fourth thoracic ganglion is the only one of any considerable 
 size ; it appears to be shared between the aorta and the pulmonary plexus. A number 
 of these aortic filaments sometimes converge towards certain small knots or ganglia, 
 which are arranged in front or along the sides of the aorta, and give off a number of fil- 
 aments. 
 
 The first thoraci© ganglion sends some twigs to the cardiac plexuses ; and not unfre- 
 
 * In one subject I found a yery remarkable disposition of the branches for the four inferior thoracic gang-lia. 
 Some small twigs from these four ganglia terminated in a minute gangliform structure, which gave off the 
 branches to the spinal nerves. It will be seen that the same arrangement frequently occurs in the lumbal 
 region. 
 
THE SPLANCHNIC NERVES. ISIJJJ 
 
 quently the inferior cardiac nerve proceeds from this ganglion. Some filaments from the 
 same ganglion are distributed to the lower part of the longus colli muscle. 
 
 Lobstein (De Nerco Magna Sympathetica, p. 19) describes a very delicate filament from 
 this ganglion, which perforates the anterior common vertebral ligament, and enters the 
 substance of one of the vertebrae. A similar filament appears to me to be given off by 
 all the cervical, thoracic, lumbar, and sacral s)Tnpathetic ganglia. The vertebrae like the 
 other bones, are provided with nerves, which are overlooked in a hasty examination 
 from their excessive tenuity. 
 
 The Splanchnic Branches. — ^These constitute the splanchnic nerves, which require a 
 separate description. 
 
 The Splanchnic Jferves. 
 
 The splanchnic nerves are divided into the great splanchnic and the small splanchnic 
 or renal * 
 
 The Great Splanchnic Nerve. — ^The great splanchnic is a white nerve, and has no re- 
 semblance to the ganglionic nerves. It is formed in the following manner : a thick 
 branch derived from the sixth and seventh thoracic ganglia, sometimes also from the 
 fifth, and even from the fourth ganglion (see fig. 302), passes downward and inward upon 
 the side of the dorsal vertebrae : this branch is joined by a series of three or four smaller 
 branches given off not only from the succeeding thoracic ganglia, but also from the com- 
 municating cords between them ; these branches {g g) are parallel to each other, and 
 pass obliquely downward and inward. The eleventh and twelfth thoracic ganglia never 
 assist in the formation of the great splanchnic nerve. 
 
 The branches just mentioned unite on each side to constitute the great splanchnic 
 nerves, which have the same relation to the thoracic ganglia that the cardiac nerves 
 have to the cervical ganglia : it is important to remark that the ganglionic nerves of the 
 thoracic viscera are derived from the cervical ganglia of the sympathetic, and that the 
 ganglionic nerves of the abdominal viscera are given off from the thoracic ganglia. 
 
 In general, the great splanchnic nerve arises by four roots ; but not unfrequently it 
 arises only by two, which then represent the four origins. 
 
 If, after having macerated the parts in diluted nitric acid, an attempt be made to de- 
 termine exactly the highest point from which the great splanchnic nerve originates, it 
 will be seen that the white filaments of which this nerve is composed are already dis- 
 tinct opposite the third thoracic ganglion, and, moreover, that they are merely in contact 
 with the trunk of the sympathetic and with the ganglia, and are continuous with the 
 coomiunicating branches from the spinal nerves. Anatomy, therefore, most clearly 
 proves that the splanchnic nerve is continuous with the spinal nerves. 
 
 Thus formed and completed opposite to the eleventh rib, the great splanchnic nerve 
 passes downward and inward in front of the vertebral column ; it becomes flattened and' 
 widened, perforates the diaphragm, the fibres of which separate to allow it to pass 
 through, and immediately terminates in the semilunar ganglion {x). An oUve-shaped 
 ganglion is not unfrequently found upon the great splanchnic, at a short distance before 
 the nerve passes through the diaphragm.* 
 
 The Small Splanchnic, or Renal Nerves.-^ think it proper to include in the same de- 
 scription the lesser splanchnic nerve of authors, and the posterior renal nerves of Walter, 
 the distinction between these nerves appearing to me to be quite arbitrary. They are 
 two, ani sometimes three in number. The highest is named the small splanchnic (h) ; it 
 arises from the eleventh thoracic ganglion, and sometimes from both the tenth and the 
 eleventh. The lowest, which is the renal nerve of authors, is larger than the preceding, 
 and is derived from the twelfth thoracic ganglion (f) : it often gives off a small fileunent 
 to the first lumbar ganglion, and in a great number of cases this is the only means of 
 communication between the thoracic and the lumbar ganglia of the sympathetic. In 
 such a case, the series of ganglia is said to be interrupted ; but a complete interruption 
 never exists. 
 
 The small splanchnic or renal nerves exactly resemble the separate or single origins 
 of the great splanchnic, with which they form a continuous series. They arise in the 
 same manner, from the two or three inferior thoracic ganglia. They pass inward and 
 downward, parallel to and on the outer side of the great splanchnic, perforate the crus 
 of the diaphragm either to the outer side of or at the same point as the great nerve, and 
 enter the renal and aortic plexuses ; they are often shared between these two plexuses 
 and the great splanchnic nerve. The highest of the small splanchnic nerves rather fre- 
 quently anastomoses with the great splanchnic, or even becomes entirely blended with it.t 
 
 * Lobstein has recorded a case (p. 2) mwhich this unusual ganglion on the great splanchnic was of a semi- 
 lunar shape, and gave off, from its convex side, seven or eight slender filaments, which accompanied the aorta 
 and were all lost in the diaphragm ; he has also mentioned another case, in which three filaments arose from 
 this ganglion, two going to the solar plexus, and the third to the mesenteric plexus. 
 
 t Among the numerous varieties which I have observed in the formation of the small splanchnic nerves, I 
 would especially notice the following: a twig from the eleventh thoracic ganglion, and one from the great 
 splanchnic nerve, terminated in a small ganglion ; from this ganglion were given oflf several filaments that 
 were lost ni)on the aorta, and also a small cord which joined with a twig from the twelfth thoracic ganglion, 
 and was di.itributed in the ordinary manner. 
 
 5R 
 
866 NEUROLOGY. 
 
 The Visceral Ganglia and Plexuses in the Abdomen. 
 
 As the semilunar ganglia and the visceral plexuses in the abdomen form the continuation 
 of the splanchnic nerves, it is not only theoretically, but practically convenient to enter 
 upon their description now. 
 
 The central point of all these ganglia and plexuses is situated at the epigastrium, and 
 is formed by a ganglionic plexus, named the solar or epigastric plexus. 
 
 The Solar or Epigastric Plexus. 
 
 The solar plexus (opposite x,fig. 302) is formed by an uninterrupted series of ganglia, 
 extending from the great splanchnic nerve of the one side to its fellow of the opposite side. 
 From this point as from a centre proceed a great number of branches, which have been 
 compared to the rays of the sun, and hence the term solar plexus. 
 
 This solar plexus, which is regarded by physiologists as the centre of the nervous sys- 
 tem of nutritive life, is deeply seated in the epigastric region, and might therefore be 
 called the epigastric nervous centre ; it is situated in the median line, in front of the aorta, 
 around the coeliac axis, and above the pancreas ; it is bounded on each side by the supra- 
 renal capsules, and is of too irregular a shape to be clearly defined. The ganglia of 
 which it is composed, the solar ganglia, are as irregular and variable as the plexus it- 
 self They consist of thick and swollen cords, or ganglionic arches or circles, arranged 
 in a network, in the meshes of which are found some lymphatic glands easily distin- 
 guishable from the nervous ganglia and cords. Anatomists, in general, describe only the 
 two extreme ganglia of the solar plexus, in which the great splanchnic nerves terminate ; 
 these are the semilunar ganglia (x), so called from their shape, but which are subject to 
 much variety both in form and size. Their convex border, which is turned downward, 
 is divided into several teeth, from each of which a pencil of nerves is given off; a great 
 number of filaments are also given off from their concave border, which is directed up- 
 ward. These ganglia are situated close to the supra-renal capsules ; they are often 
 without any regular form, and, as it were, divided into fragments. 
 
 A single glance at the solar plexus will suffice to convince us of the impossibility of 
 extirpating it, as some experimenters pretend to have done, in living animals. 
 
 The great splanchnic nerve of each side (g), a part of the small splanchnic nerves (A), 
 and the right pneumogastric nerve (j)'), end in the solar plexus. I have also seen the 
 right phrenic enter this plexus. 
 
 From it, as from a centre, plexuses are given off for all the arteries arising from the 
 fore part of the aorta, and also for the renal and spermatic arteries. The plexuses for 
 the renal arteries and the inferior mesenteric artery are completed by the visceral nerves 
 derived directly from the lumbar ganglia. There are two diaphragmatic plexuses, a coeliac 
 plexus, a superior and an inferior mesenteric plexus, renal plexuses, spermatic or ova- 
 rian plexuses, and supra-renal plexuses. 
 
 All the nerves given off from the solar ganglia are gray, and very small ; they are al- 
 ways plexiform, and are generally strong on account of the thickness of their neurilemma. 
 
 The Diaphragmatic and Supra-renal Plexuses. 
 
 The diaphragmatic or phrenic plexuses are small ; they are given off from the upper part 
 of the solar plexus, and reach the phrenic arteries, with which they enter the diaphragm ; 
 they at first lie beneath the peritoneum, but afterward dip into the substance of the fleshy 
 fibres of the muscle, and do not exactly follow the course of the vessels. In some cases 
 I have been able to ascertain that they anastomose with the filaments of the phrenic 
 nerve : they always run in nearly the same direction. 
 
 The diaphragmatic plexus of the right side is larger than that of the left. I have seen 
 two ganglia, upon the right cms of the diaphragm, which formed the origin of the right 
 diaphragmatic plexus and of some hepatic nerves. 
 
 I arrange the plexuses of the supra-renal bodies with the preceding, because they have 
 so many relations with them. They arise directly from the semilunar ganglia, by two 
 very delicate pencils of nerves, which reach the back of the supra-renal arteries, and are 
 lost in the substance of the supra-renal bodies. Several filaments from the diaphrag- 
 matic plexuses join them, passing in front of the arteries. The supra-renal plexuses are 
 large in proportion to the size of the organs they supply. 
 
 The Cceliac Plexus. 
 The coeliac plexus is one of the principal divisions of the solar plexus, of which it is 
 • the immediate prolongation, so that it is almost impossible to distinguish one from the 
 ■ other ; it surrounds the coeliac axis, and immediately divides, like it, into three plexuses, 
 .the coronary of the stomach, the hepatic, and the splenic. 
 
 The Coronary Plexus of the Stomach. — This is given off from the upper part of the solar 
 
 t plexus ; it receives some filaments from the right pneumogastric, before that nerve joins 
 
 ;. the solar plexus ; of these filaments, some ramify upon the cardia, while the remainder 
 
 follow the coronary artery along the lesser curvature of the stomach, and anastomose 
 
 ■jwith the pyloric filaments of the hepatic plexus. It follows, therefore, that the stomach 
 
THE SUPERIOR MESENTERIC PLEXUS. 867 
 
 is principally supplied by the pneuraogastric nerve. The filaments from the coronary 
 plexus of the stomach, as well as those of the pneumogastric nerve, after having run for 
 some distance beneath the peritoneum, perforate the muscular coat of the stomach, and 
 appear to be partly lost in it and partly in the mucous membrane. 
 
 The hepatic plexus is of very considerable size, and might be divided, after the example 
 of Lobstein, into an anterior and a posterior plexus. The anterior accompanies the hepat 
 ic artery, and is formed by some twigs from the right pneumogastric, and by seven or 
 eight large gray, cylindrical filaments from the left semilunar ganglion, which are joined 
 by two or three branches from the right semilunar ganglion. 
 
 The posterior hepatic plexus accompanies the vena portae, and is derived almost entirely 
 from the right semilunar ganglion ; it is also composed of grayish, thick, cylindrical cords. 
 I would especially notice one cord, which is remarkable both from its size and its course ; 
 it arises directly from the solar ganglion of the right side, passes in a horizontal and 
 curved direction to reach the gastro-hepatic omentum, and continues horizontally be- 
 tween the layers of that omentum, in front of the lobulus Spigelii ; it then ascends to 
 the transverse fissure of the liver, becomes situated beneath the vena portae, and may 
 be traced along that vein into the interior of the liver. I have seen this great he- 
 patic branch come directly from two ganglia situated upon the right crus of the dia- 
 phragm. 
 
 Before reaching the liver, the hepatic plexus gives off a secondary plexus of consider- 
 able size, around the right gastro-epiploic artery, the right gastro-epiploic plexus ; it is 
 considerably augmented by filaments which are derived immediately from the solar 
 plexus, and perforate the pancreas. 
 
 The hepatic plexus also furnishes branches to the pylorus and the lesser curvature of 
 the stomach, to the pancreas, to the great curvature of the stomach, and to the great 
 omentum. The pylorus, therefore, and the great curvature of the stomach, are supplied 
 almost exclusively by the hepatic plexus.* 
 
 The hepatic plexus likewise gives off a small cystic plexus, which is easily seen beneath 
 the peritoneum, surrounding the cystic artery as far as the gall-bladder. 
 
 Diminished in size, from having given off a series of branches and plexuses, the he- 
 patic plexus gains the transverse fissure of the liver, divides like the hepatic artery and 
 vena portae, and may be traced for some distance in the capsule of Glisson. 
 
 All the nerves of the liver are gray, but very strong. 
 
 The Splenic and Pancreatic Plexuses. — The splenic plexus is not so remarkable for the 
 number as for the size of the filaments of which it is composed ; it surrounds the splenic 
 artery, furnishes some twigs to the pancreas, and it also gives off the left gastro-epiploic 
 plexus, which is smaller than the right, is situated upon the great curvature of the stom- 
 ach, and supplies that organ and the great omentum. The splenic plexus also gives off 
 nervous filaments to the great cul-de-sac of the stomach, and being thus very much di- 
 minished in size, reaches the hilus of the spleen, within which organ it can be easily tra- 
 ced in man, and still more easily in the larger animals, along the ramifications of the 
 bloodvessels. 
 
 These nerves are gray, and very strong. The numerous filaments which pass to the 
 pancreas, and form a plexus around its arteries, constitute the pancreatic plexus, which 
 may be regarded as a dependance of the splenic plexus. 
 
 The Superior Mesenteric Plexus. 
 
 The superior mesenteric plexus, which may be regarded as the lower division of the bi- 
 furcation of the epigastric plexus, is the largest of all the abdominal plexuses ; it sur- 
 rounds the superior mesenteric artery, forming an extremely thick plexiform sheath for 
 it ; it passes below the pancreas, enters the substance of the mesentery {w) with the 
 artery, and divides, like that vessel, into a great number of secondary plexuses, which 
 are distributed to all the parts supplied by the artery, namely, to the whole of the small 
 intestine, excepting the duodenum, and to the right portion of the great intestine. 
 
 Without entering into tedious and useless details, I shall content myself with a few 
 remarks upon the general distribution of these nerves. 
 
 The mesenteric nerves are remarkable for their length, their number, and their 
 strength. I am certain that their neurilemmatic sheath is proportionally much thicker 
 than that of other nerves. They are placed at variable distances from the vessels, and 
 proceed in a straight line in the substance of the mesentery towards the intestine, with- 
 out giving off any filaments : at a short distance from the concave border of the intes- 
 tine, they either pass directly to the bowel, or else they anastomose at an angle or in 
 an arch ; from the convexity of these anastomotic arches the filaments for the intestine 
 are given off. 
 
 There is never more than one series of anastomotic nervous arches in the mesentery, 
 whatever may be the number of rows of vascular arches ; the single nervous arch al- 
 
 * The cardia and the lesser curvature of the stomach are the parts which are the most abundantly provided 
 with nerves. The pylorus, to which we attribute such great .".ensibility, has incomparably fewer. 
 

 NEUROLOGY. 
 
 ways cdiTesponds fb the vascular arch nearest to the intestine : the filaments ■which 
 proceed from it are exceefl'ngly minute.* 
 
 The nervous filaments pt netrate the intestine by its adherent border, run for some 
 time between the serous ai .d muscular coats, perforate the latter, to which they give 
 some twigs, then spread out lO the fibrous coat, and finally terminate in the mucous mem- 
 brane 
 
 The Inferior Mesenteric Plexus. 
 
 The inferior mesenterf pit ms (n) is formed by some twigs from the epigastric plexus, 
 :r, rather, from the sup( ric; mesenteric plexus, with which it is continuous on the front 
 lif the abdominal aorta ; ai l, secondly, by some branches from the lumbar sympathetic 
 4;anglia, which, as hereai'^tr stated, constitute the lumbo-aortic plexus. The meshes of 
 ..he inferior mesenteric plexus are by no means so close as those of the superior mesen- 
 teric plexus. 
 
 The inferior mesenteric plexus, like the artery by which it is supported, supplies the 
 Left half of the transverse arch of the colon, the descending colon, the sigmoid flexure, 
 and the rectum : of its filaments, those which accompany the left colic arteries are re- 
 markable for their tenuity, their length, and for giving no branches in their course to 
 the intestine. I would particularly notice the twig which accompanies the left superior 
 colic artery. It is not uninteresting to remark, that these nerves are more numerous in 
 the iliac meso-colon, which supports the sigmoid flexure, than at any other point. 
 
 The inferior mesenteric plexus, thus diminished by having given off other smaller 
 plexuses, terminates, like the inferior mesenteric artery, by bifurcating ; the two divis- 
 ions of this bifurcation are called the hemorrhoidal plexuses ; they surround the two divis- 
 ions of the artery, viz., the superior hemorrhoidal arteries, and terminate partly in the 
 hypo-gastric plexus and partly in the rectum. 
 
 The Renal and Spermatic, or Ovarian Plexuses. 
 
 The renal plexuses are extremely complicated : they are formed by branches from the 
 solar plexus, and by the two or three small splanchnic or renal nerves, and terminate 
 almost exclusively by surrounding the renal artery. 
 
 The two spermatic plexuses in the male, and ovarian plexuses in the female, are derived 
 principally from the renal plexuses. The spermatic plexuses are destined exclusively for 
 the testicles ; the ovarian plexuses, like the arteries of the same name, are distributed 
 both to the ovaries and the uterus. The intimate connexions between the nerves of the 
 kidneys and testicles in the male, and those of the kidneys, ovaries, and uterus in the 
 female, deserve the most particular attention of anatomists. 
 
 The Lumbar Portion of the Sympathetic System. 
 
 The lumhar portion of the trunk of the sympathetic {II, fig- 302) is situated in front of the 
 vertebral column, along the inner border of the psoas muscle. The ganglia of this re- 
 gion are therefore nearer the median line than the thoracic ganglia ; but the inferior lum- 
 bar ganglia not unfrequently deviate from their ordinary position, and approach the lum- 
 bar nerves as these emerge from the spinal canal : in this case, they are concealed by the 
 psoas muscle. The lumbar ganglia of the sympathetic vary much in size ; some of them 
 are so small that they would escape notice, if their grayish colour did not distinguish them 
 from the rest of the trunk of the sympathetic. 
 
 The number of these ganglia is also variable ; there are rarely more than four. 
 Two or three ganglia are often blended into a gangliform cord ; this fusion may be easily 
 recognised by the arrangement of the communicating filaments between it and the lum- 
 bar spinal nerves. 
 
 In one subject, the twelfth thoracic ganglion on the right side was blended with the 
 first lumbar ganglion : a small filament, corresponding in length to the thickness of two 
 vertebrae, established a communication between this ganglion aiid a large gangliform 
 cord, which represented by itself the four inferior lumbar ganglia. On the left side, the 
 second and third lumbar ganglia were united, and the fifth was blended with the first 
 sacral. This fusion of the lumbar ganglia almost constantly exists, and it establishes a 
 close analogy between the lumbar portion of the sympathetic and the cervical portion, 
 which, as we have already seen, has only three, and frequently only two ganglia. It 
 proves that the superior cervical ganglion may be regarded as representing five superior 
 cervical ganglia and the ganglia corresponding to the two sets of cranial nerves, and 
 that the inferior cervical ganglion may be viewed as the representative of two lower cer- 
 vical ganglia, when the middle ganglion is wanting. 
 
 Moreover, the trunk of the sympathetic is not unfrequently interrupted either between 
 the twelfth thoracic and the first lumbar ganglion, or between the last lumbar and the 
 
 ' In one case I found a very remarkable anastomosis. Four filaments, proceeding from four opposite points, 
 converged towards a common centre ; but, as they were about to cross, they diverged from one another so as 
 to intercept a lozenge-shaped space. Two of these might lie regarded as filaments of origin, and the other 
 two ;i5 terminating filaments 
 
LUMBAR PORTION OF THE SYMPATHETIC SYSTEM. 869 
 
 first sacral ganglion : this interruption is, however, more apparent than real, for. as I 
 have already stated, the continuity between the twelfth thoracic and the first lumbar 
 ganglion is always established by means of a small twig from the renal nerve. 
 
 The branches of the lumbar ganglia may be divided into the branches of communi- 
 cation between the ganglia ; the external branches, and the internal branches : besides 
 these, there are some small and very delicate filaments, which enter the bodies of the 
 yertebrse. 
 
 The Communicating Branches between the Ganglia. 
 
 These communicating branches consist of one or more white cords extending between 
 every two ganglia ; they scarcely ever have the gray appearance and ganglionic struc- 
 ture usually found in similar branches of conununication : the communicating filament 
 between the fourth and fifth lumbar ganglion is often wanting. 
 
 The External Branches. 
 
 These are the branches (at d) which communicate with the lumbar nerves. I c6n- 
 ceive that they are furnished by the lumbar spinal nerves to the lumbar ganglia of the 
 sympathetic. There are generally two, but sometimes three for each ganglion ; they 
 arise from the anterior branches of the several lumbar nerves, as they emerge from the 
 inter- vertebral foramina ;* they accompany the lumbar arteries, along the grooves upon 
 the bodies of the lumbar vertebrae, and terminate in the corresponding ganglia ; they are 
 usually directed obliquely downward. 
 
 In general, each ganglion receives branches not only from the corresponding lumbar 
 nerve, but also from the nerve next above it. Thus, two branches end in the second 
 lumbar ganglion, one from the first, and another from the second lumbar nerve ; the 
 third ganglion receives filaments from the second and third lumbar nerves ; when one 
 ganglion is wanting, its place is supplied by the next, which receives its own proper 
 branches, and also those belonging to the absent ganglion. One ganglion not unfrequent 
 ly communicates with three lumbar nerves. 
 
 When several ganglia are united into one, it is easy to conceive that this single gan- 
 glion must receive aU the filaments corresponding to those ganglia. It is also easy to 
 understand that these filaments must be directed more or less obliquely either upward 
 or downward, and that they will correspond in length to the distance between the lum- 
 bar nerves and the single ganglion, the superior filaments being directed downward, 
 and the inferior filaments upward. 
 
 A very remarkable condition of the branches of communication between the lumbar 
 nerves and the sympathetic ganglia consists in the existence of certain ganglia or swell- 
 ings upon them ; and the ahnost indefinite anomalies observed in this particular are no 
 less remarkable. I have found as many as three ganglionic nodules upon the same 
 communicating branch: sometimes, when the two or three communicating branches 
 reach the side of a vertebra, they unite in a ganglion, from which two or three other 
 branches are given off to the proper sympathetic ganglion, t 
 
 Moreover, these ganglia, like all the irregular ganglia, rarely present that peculiar 
 character which is common to the regular ganglia, namely, that of forming a centre in 
 which a certain number of filaments end, and from which others are given off. 
 
 The Internal, or Aortic and Splanchnic Branches. 
 The internal branches from the lumbar ganglia are the aortic and the lumbar splanchnic 
 branches, and form a continuous and uninterrupted series with the aortic and splanchnic 
 branches from the thoracic ganglia ; so that the internal branches from the first (/) and 
 sometimes from the second lumbar ganglion join the branches from the eleventh and 
 twelfth thoracic ganglia, to form a small splanchnic nerve, which is shared between the 
 solar and the renal plexus. Some small gangliform nodules are occasionally found upon 
 the course of these branches, among which are some very delicate filaments, which evi- 
 dently pass into the bodies of the lumbar vertebrae. All these internal branches assist 
 in the formation of the lumbar splanchnic, or pelvic visceral nerves. 
 
 The Lumbar Splanchnic Serves and the Visceral Plexuses in the Pelvis. 
 
 The lumbar splanchnic nerves (at k) pass inward in front of the aorta, below the su- 
 perior mesenteric artery, and anastomose with each other and with those of the opposite 
 side to form a very complicated plexus, which is completed by a very considerable pro- 
 longation from the superior mesenteric plexus. 
 
 This plexus (n), which may be called the lumbo-aortic plexus, surrounds all that por- 
 tion of the aorta which is included between the superior and inferior mesenteric arteries ; 
 in the intervals between the nervous filaments are found lymphatic glands, which should 
 be carefully distinguished from some nervous ganglia which form part of the plexus. 
 
 The lumbo-aortic plexus is bifurcated below ; one portion of it passes upon the infe- 
 
 * These communicating branches frequently arise in the substance of the psoas muscle from twigs derived 
 from the lumbar plexus. 
 
 f This dispositiou is well seen in the beautiful plate of the sympathetic published by M. Manec. 
 
NEUROLOGY. 
 
 rior mesenteric artery to constitute the greater part of the inferior mesenteric plexiis 
 (below n) ; while the other portion descends upon the aorta, and even a little below the 
 bifurcation of that vessel, and ends between the common iliac arteries, in front of the 
 sacro-vertebral angle, from which it is separated by the common iliac veins. Some fila- 
 ments are prolonged around the common iliac and the external and internal iliac arter- 
 ies and their branches. 
 
 The aortic portion of the lumbo-aortic plexus bifurcates below into two secondary plex 
 if arm cords, one right and the other left, which pass downward upon the sides of the rec 
 turn and bladder, and enter the right and left hypogastric plexuses, which are almost 
 entirely formed by these cords. 
 
 The Hypogastric Plexuses. 
 
 The hypogastric plexuses (m) are among the great plexuses of the body ; they supply 
 the rectum and the bladder in both sexes, and also the prostate and testicle in the male, 
 and the vagina, uterus, and Fallopian tubes in the female. 
 
 There are two hypogastric plexuses, one on the right, the other on the left side. They 
 are situated upon the lateral and inferior surfaces of the rectum and bladder in the male, 
 and of the rectum, vagina, and bladder in the female ; they are distinct from each other, 
 and are connected not by median anastomoses, which I have never been able to detect, 
 but through the lumbo-aortic plexus, by the bifurcation and spreading out of which they 
 may be said to be formed. The hypogastric plexuses, from the enlargement and areolar 
 disposition of their component cords, very closely resemble the solar plexus. 
 
 Each plexus is formed essentially by one of the two divisions of the lumbo-aortic 
 plexus ; it is also joined by some filaments from the inferior mesenteric plexus, by some 
 very small twigs from, the sacral ganglia, among which those derived from the third sa- 
 cral ganglion are especially remarkable ; and, lastly, by some twigs from the anterior 
 branches of the sacral nerves (see Sacral Nervks). 
 
 Formed by a combination of filaments from these different sources, each hypogastric 
 plexus gives off a hemorrhoidal, a vescical, a vaginal, a uterine, and a spermatic or ova- 
 rian plexus ; all of these plexuses, like the hypogastric plexus itself, are found on each 
 side of the body. 
 
 The inferior hemorrhoidal plexuses are blended with the superior hemorrhoidal plex- 
 uses, which, as already stated, are the terminations of the inferior mesenteric plexus ; 
 they pass behind and in front of the rectum. The filaments belonging to the anterior 
 branches of the sacral nerves may be distinguished from those belonging to the sympa- 
 thetic system by the difference in the colour of the two kinds of nerves. 
 
 The vesical plexuses are composed of a great number of exceedingly small filaments. 
 They are situated upon the sides of the posterior fundus (bas-fond) of the bladder, on the 
 outer side of the ureters, and are divided into two sets, viz., ascending vesical nerves, 
 which pass upward upon the sides of the bladder, embrace the outer and inner surfaces 
 of the ureters, and ramify upon the anterior and posterior surfaces of the bladder ; and 
 horizontal vesical nerves, which run forward upon the sides of the fundus of the bladder, 
 externally to the large plexus of veins found in that situation, and spread out into ex- 
 tremely delicate filaments, of which some enter the substance of the bladder, especially 
 at its neck, while the others, in considerable numbers, turn round the prostate gland, 
 and are distributed within it ; one of the prostatic filaments may be traced into the mem- 
 branous portion of the urethra. 
 
 The Plexuses for the Vesictila Seminales, and Vasa Deferentia, and Testicles. — Some of 
 the filaments situated on the inner side of the ureters surround the vesiculae seminales, 
 and are lost in them ; these are very small ; two or three remarkably large filaments run 
 upward along each vas deferens ; having reached the inguinal ring, they unite with the 
 corresponding spermatic plexus, which is a production of the renal plexus, and descend 
 to the testicle. 
 
 The branches for the prostate, vesiculae seminales, vasa deferentia, and testicles, are 
 represented in the female by the utero-vaginal, ovarian, and tubal nerves. 
 
 The Uterine Nerves. — Notwithstanding the figures of the sympathetic published by 
 Walter, in which the nerves of the uterus are well represented, and notwithstanding the 
 still more explicit description given of them by Hunter, most anatomists continue to en- 
 tertain doubts regarding the existence of the uterine nerves. Lobstein, in his work on 
 the Sympathetic, published in 1822, even denied them altogether ; but Tiedemann, in the 
 same year, published two beautiful figures, representing the nerves of the gravid uterus.* 
 
 The uterine nerves are derived from several sources. I have already stated that the 
 plexuses surrounding the ovarian arteries, which are productions of the renal plexuses, 
 are distributed, like the vessels by which they are supported, both to the uterus and the 
 ovaries. 
 
 It appears to me that the ovarian nerves and vessels have a similar arrangement, that 
 is to say, that the uterine branches derived from the ovarian plexuses are larger than the 
 ovarian nerves properly so called. 
 
 * Tabula Nervorum Uteri, Heidelberg, 1822, folio. 
 
GENERAL VIEW OF THE SYMPATHETIC SYSTEM. 8H 
 
 The tubal nerves are also derived from the ovarian plexuses. 
 
 The uterine nerves derived from the hypogastric plexuses are divided into ascending 
 branches, which run upward along the lateral borders of the uterus, pass forward and 
 backward upon the surfaces of that organ, and terminate in its substance ; and into de- 
 scending branches, which run along the sides of the vagina, and terminate in it. These 
 vaginal nerves appear to be inseparably blended with the vesical and hemorrhoidal 
 nerves.* 
 
 Such are the divisions of the hypogastric plexuses ; analogy, rather than direct obser- 
 vation, has led to the admission of the existence of gluteal, ischiatic, and internal pudic 
 plexuses ; in fact, of plexuses around all the branches of the internal iliac arteries. 
 
 The Sacral Poetion of the Sympathetic System. 
 
 The sacral portion of the sympathetic (s s, fig. 302) is formed on each side by a cord en- 
 larged at intervals, and situated on the inner side of, and along the anterior sacral fo- 
 ramina. 
 
 It forms a continuation of the lumbar portion of the sjnnnpathetic ; but sometimes there 
 appears to be an interruption in the ganglionic chain, between the fifth lumbar ganglion 
 and the first sacral. This interruption is merely apparent ; it is never complete. The 
 sacral trunks of the sympathetic of the right and left sides gradually approach each other 
 as they descend, corresponding in this respecf to the anterior sacral foramina. 
 
 The sacral ganglia, which are rarely five, more commonly four, and sometimes three 
 in number, are occasionedly collected into a small gangliform enlargement, situated be- 
 tween the first and second anterior sacral foramen ; the first sacral ganglion is some 
 times double, and at other times it rather resembles a gangliform cord than a true gan- 
 glion. 
 
 The mode of connexion between the first sacral and the last lumbar ganglion is sub- 
 ject to much variety. + The manner in which the sacral portion of the sympathetic terr- 
 minates is also somewhat variable. The following is the arrangement most generally 
 admitted : a filament proceeds from the last sacral ganglion, which is usually the fourth, 
 and forms an anastomotic arch with its fellow of the opposite side, in front of the base 
 of the cocc)rx. At their point of junction is often found a small ganglion (ganglion inp- 
 par, c), from which certain terminal filaments are given off. Sometimes there is neither 
 a coccygeal ganglion nor any anastomosis, properly so called, but the terminal filaments 
 are distributed in the usual way. I have not been able to trace these filaments beyond 
 the periosteum of the coccyx and the sacro- sciatic ligaments. 
 
 Like the other ganglia of the sympathetic, the sacral ganglia present communicating 
 branches with each other ; rather large external branches derived from the corresponding 
 sacral nerves ; internal branches, which anastomose with those of the opposite side, in 
 front of the sacrum, and surround the middle sacral artery. Some of these filaments I 
 have distinctly seen entering the substance of the sacrum ; and^ lastly, very small ante- 
 rior branches (y), some of which join the hypogastric plexuses, while the others termi 
 nate directly upon the rectum. 
 
 General View of the Sympathetic System. 
 
 The following dissection is necessary, in order to present a correct general idea of the 
 S)mapathetic system. 
 
 Take a spinal column which has been macerated in diluted nitric acid, remove the 
 bodies of the vertebrae, leaving, if it be wished, the inter- vertebral substances ; be very 
 careful to preserve the branches of communication between the sympathetic and the cra- 
 nial and spinal nerves. 
 
 It is then clearly seen that the two gangliated trunks of the S3rmpathetic are connect- 
 ed with the cerebro-spinal axis by as many roots, or small groups of roots,t as there are 
 cranial and spinal nerves ; it is, moreover, no less evident that the communicating 
 branches between the ganglionic chain and the spinal nerves do not proceed from the 
 ganglia, but from the spinal nerves ; so that it may be stated as a demonstrated ana- 
 tomical fact, that the sympathetic system has its origin in the cerebro-spinal system <) 
 
 * [Dr. Lee has recently examined minutely the distribution of the nerves of the unimpregnated and fravid 
 uterus. He has described (Anatomy of the Nerves of the Uterus, with plates, 1841, and Proceedings of the 
 Royal Society, No. 49) several large uterine plexuses ; also, several " large ganglia on the uterine nerves, and 
 on those of the vagina and bladder ;" and, farther, '' two great ganglia situated on the sides of the neck of the 
 uterus."] 1 • • J u 
 
 t In one case, the continuation of the lumbar portion of the sympathetic deviated outward, and joined the 
 fifth lumbar nerve ; a very small filament only formed the communication between the last lumbar ganglion 
 and the first sacral. In another case, these two filaments proceeded from the last lumbar ganglion of the right 
 side, t'ae inner of which joined the first sacral ganglion of the opposite side, crossing over the sacro-vertebral 
 
 t It must be remembered that there are always two, and sometimes three communicating branches between 
 the sympathetic and each of the spinal nerves. 
 
 4 These facts in human anatomy are in perfect accordance with the observations in comparative aiiatomr 
 made by Meckel and Weber, namely, that the development of the sympathetic system is in direct ratio with 
 that of the cerebro-spinal system ; tliat the former is more developed in man than in any other animal, and 19 
 proportionally larger in the fietus than in the adult. 
 
872 NEUROLOGY. 
 
 The sympathetic trunks of the right and left side generally anastomose below in front 
 of the coccyx ; it has been somewhat hastily affirmed that they anastomose above, either 
 upon the pituitary body, or upon the anterior communicating artery of the brain ; the 
 true anastomoses of the two halves of the sympathetic system are in the central and 
 median plexuses. 
 
 If, after having acquired this general idea of the trunks of the sympathetic, its neuri- 
 lemma be removed by continued maceration in water, the connexions of the branches 
 given from the spinal nerves to the ganglia, with the branches given from the ganglia to 
 the viscera, may then be ascertained : it then becomes evident, that the greater number 
 of the branches from the spinal nerves do not penetrate to the centre of the ganglia, but 
 expand, as it were, upon their surface, and divide into two sets of filaments ; of these, 
 some are applied to the surface of a ganglion, and proceed directly to form the internal 
 or visceral branches ;* while the others assist in forming the cords of communication 
 between one ganglion and another, and divide into ascending and descending filaments, 
 of which the latter are the more numerous. They all run along the outer side of the cords 
 of communication, and afterward become visceral branches themselves ; it is doubtful 
 whether any filament arises in the interior of a ganglion ; the continuity of them all can 
 be traced completely through these bodies. 
 
 It follows, therefore, that it is anatomically shown that the visceral nerves given off 
 from the sympathetic are connected or belong to a very great nimiber of spinal nerves 
 at once, and always to spinal nerves much higher than that portion of the sympathetic 
 from which the visceral branches are immediately given off; and again, that the vis- 
 ceral or splanchnic nerves, the actual origins of which we have seen to be so complica- 
 ted and so remote from their apparent origins, always run a very long course before 
 reaching their destination. Thus, the splanchnic nerves of the thorax or the cardiac 
 nerves are derived from the cervical ganglia ; the splanchnic nerves of the abdomen are 
 given off, for the most part, by the thoracic ganglia ; and most of the splanchnic nerves 
 of the pelvis proceed from the lumbar ganglia. Nevertheless, the proper ganglia of each 
 splanchnic cavity complete the visceral nerves belonging to that cavity. Thus, the first 
 thoracic ganglion assists in the formation of the cardiac nerves ; the superior lumbar 
 ganglia in that of the visceral nerves of the abdomen ; and the sacral ganglia in that of 
 the pelvic nerves. 
 
 The visceral nerves sometimes pass directly to the viscera from the ganglia of the 
 sympathetic, and sometimes indirectly, after being mingled and combined in plexuses. 
 
 There is no relation between the branches which enter and those which pass out of 
 the several visceral plexuses, so that the branches which proceed from the ganglia and 
 trunk of the sympathetic to those plexuses must be regarded, not as branches of forma- 
 tion, but as branches of communication. 
 
 The visceral plexuses are also formed in a very peculiar manner, not only by inter- 
 laced nerves, but by nerves and ganglia, and these nerves themselves present a gangli- 
 onic structure altogether different from the fasciculated and plexiform structure of other 
 nerves. 
 
 There are four great visceral plexuses : the pharyngeal plexus, the cardiac plexus, the 
 solar plexus, and the hypogastric plexus ; the largest of all these is the solar plexus, 
 which, both in an anatomical and in a physiological point of view, deserves the title of 
 the abdominal brain, which was given to it by Wrisberg. These four great plexuses 
 may also be very properly regarded as nervous centres, to which all the physiological 
 and pathological phenomena of the nutritive system are singly or collectively referred. 
 
 These visceral plexuses differ as much from the ganglionic chain formed by the two 
 trunks of the sympathetic as these trunks differ from the spinal cord itself : in these 
 plexuses a sort of fusion is effected between the cerebro-spinal and the sympathetic sys- 
 tems, and also between the trunks of the sympathetic belonging to the two sides of the 
 body. 
 
 The pneumogastrie assists in the formation of three of these jdexuses ; namely, the 
 pharyngeal, the cardiac, and the solar plexus. In man there is a tendency to fusion of 
 the pneumogastrie with the sympathetic, and in the lower animals this fusion is still 
 more complete ; it is in those animals in which the sympathetic is the least developed 
 that the par vagum acquires its greatest development, and supplies the place of the for- 
 mer in reference to the intestinal canal. 
 
 The glosso-pharyngeal nerve also assists in the formation of the pharyngeal plexus, 
 and the sacral nerves contribute to that of the hypogastric plexus. 
 
 The visceral plexuses differ essentially from those formed by the cerebro-spinal nerves. 
 In the latter, the branches which emerge from the plexus are precisely the same branch- 
 es that entered it, only combined in a different manner. However inextricable they 
 may be, the plexuses of the spinal nerves are merely points in which a number of affe- 
 rent branches converge and combine together. In the visceral plexuses, on the contra- 
 ry, there is no relation, either in size or structure, between the afferent branches and 
 the plexuses themselves. 
 
 * Some filaments from the spinal nerves are seen to croFS at right angles over the anterior surface of the 
 gang^iia, and then to join the visceral nerves ilirectlv. 
 
GENERAL VIEW OF THE SYMPATHETIC SYSTEM. 
 
 873 
 
 The nerves derived from the sympathetic system differ eilso in their mode of distribu- 
 tion from the nerves of the cerebro-spinal system. In general, they form a plexiform 
 sheath around the vessels, and enter with them into the substance of organs. This ar- 
 rangement has induced some anatomists to believe that the sjrmpathetic nerves belong 
 essentially and exclusively to the vascular system, and are lost upon the coats of the 
 arteries ; others hold an opposite opinion, and deny altogether that the sympathetic 
 nerves enter the coats of those vessels. From some researches which I have made on 
 this subject, I believe that there are proper filaments for the coats of the vessels, but 
 that these are very few in number, and that by far the larger number of the nervous fila- 
 ments are intended for the several organs. It is not uninteresting to remark, that the 
 s)Tnpathetic nerves always accompany the arteries, and never the veins ; the trunk of 
 the vena portae forming the only exception to this rule. 
 
 A gray colour and a soft texture are not, as is generally stated, the peculiar character- 
 istics of the nerves of the sympathetic system ; the gray colour is observed only in a 
 portion of this system ; and the softness, which only very rarely accompanies the gray 
 colour, is confined to a very minute portion of it indeed. 
 
 There are gray cords, which are nothing more than prolonged ganglia, and are not 
 nerves, properly so called ; when examined they present no nervous structure, that is 
 to say, they contain no white funiculi which can be decomposed into primitive filaments 
 as fine as the silk fibre. Almost all the sympathetic nerves are of a white colour, which 
 is sometimes conceeiled by an unusually thick neurilemma. The structure of the white 
 nerves of the sympathetic system does not differ from that of the cerebro-spinal nerves ; 
 except that the funicidi of the former are smaller, and their arrangement is more deci- 
 dedly plexiform.* Lastly, there are some mixed nerves, partly gray and partly white, 
 which partake of the structural characters of both the gray and the white nerves, t 
 
 * See note, p. 840. 
 
 + I am much indebted to M. C.Bonamy, my private prosector, for the zeal and ability with which he ha» 
 assisted me in the numerous dissections required for the compilation of this work. 
 
 SOURCES FROM WHICH THE ILLUSTRATIVE ENGRAVINGS HAVE BEEN TAKEN. 
 
 Figs. 1 to 7, 8t, 9 to 20, 24, 25, 28 to 30, 33, 34, 36, 
 38, 41 to 45, 47, 48t, 49 to 53, 57 (Sue). 
 
 Figs. 21 to 23, 37 (Gordon). 
 
 Figs. 26, 27, 35, 58t to 60t, 61 to 70, 71t, 72 to 84, 
 106 to 110, lilt, 112, 113, 114t, 115, 116t to 123t, 124 
 to 126, 127t, 128 to 133, 141t, 147t, 155, 161, 163t, 
 169t, 170, 171t, 191t, 192, 194, 195 (Bourgery). 
 
 Figs. 39, 40, 46t, 54 to 56 (Ckeselden). 
 
 Figs. 85 to 94 (Hunter). 
 
 Fig. 95 (d.) (Retzius). 
 
 Fig. 97 (d.) (Goodsir). 
 
 Fig. 98 (Serres). 
 
 Figs. 99, 101, 102 (Blake). 
 
 Fig. lOO (T. Bell). 
 
 Figs. 103 (d.) to 105 (d.), 286 (Cloquet). 
 
 Figs. 136t, 138, 181 (Morion). 
 
 Fig. UOf (Watts). 
 
 Figs. 142, 173 to 175, 178, 231, 233, 234, 257 (Sam- 
 mrring). 
 
 Figs. 145, 160, 182, 187, 189,220,221,223t(We6er). 
 
 Figs. 152, 153 (Boyd). 
 
 Figs. 154t, 198 to 206, 208 to 218 (Tiedemann). 
 
 Fig. 156 (No. 2) (Krause). 
 
 Fig. 156 (No. 3) (Dallinger). 
 
 Figs. 157 to 159, 162 (Boehm). 
 
 Fig. 172 (Reisseissen). 
 
 Fig. 180 (d.) (Wagner). 
 
 Fig. 183 (A. Cooper). 
 
 Fig. 185 (Holier). 
 
 Figs. 207, 232t, 235 to 240, 242 to 246, 248, 249, 
 251t, 252 to 256, 258 to 265, 266, 269 to 275, 284, 285, 
 296tto301t (Arnold). 
 
 Fig. 219t (Walter). 
 
 Fig. 222t (Caldani). 
 
 Fig. 226 (Harvey). 
 
 Figs. 227, 228 (Gurlt) 
 
 Fig. 250 (Brewster). 
 
 Fig. 268 (Cruveilhier). 
 
 Figs. 281t, 283, 295 (Mayo). 
 
 Figs. 289t, 290t (Saan). 
 
 Fig. 302t (Manec). 
 
 Figs. 143 (d.), 144 (d.), 164* (d.), 179 (d.), 193+, 
 197, 241 (d.), 276 to 280, 282 (Models, Castt, and Di 
 agrams in the Museum of Anatomy, University College). 
 
 Figs. 31, 32, 96, 98* (d.), 134 (d.), 135 (d.), 137 (d.), 
 139 (d.), 146 (d.), 148 (d.), 149 (d.) to 151 (d.), 156 
 (No. 1, d.), 164, 176 (d.) to 178 (d.), 184 (d.), 186 (d.), 
 190 (d.),196 (d.),218* (d.),224 (d.),225 (d.),229 (d.), 
 230 (d.), 247 (d.), 267 (d.), 287 (d.), 288 (d.), 291 (d.) 
 to 293 (d.) (Original). 
 
 Figs. 165 to 168 (Kieman). 
 
 The mark (t), affixed to the number of a figure, indicates that such figure differs in some respects from the 
 (aiginal. The letter (d.), similarly aflixed, signifies that the figure is intended as a diagram or plan. Th« 
 asterisk (*), used occasionally, serves to distinguish between two figures bearing the same number 
 
 5S 
 
««#***'<' 
 
 '*ll^- 
 
 INDEX. 
 
 Abdomen, aponeurosis of, anterior, 300. 
 
 posterior, 305. 
 
 superficial, 297. 
 
 regions of, 352. 
 
 Abducens, nerve. See Nerve, Motor Ocul. 
 Abductor muscles. See Muscles. 
 Accessory ligaments. See Ligaments. 
 
 nerves. See Nerves. 
 
 Acetabulum, 88. 
 
 Acini of glands. See those glands. 
 
 Acromion process, 76. 
 
 Adductor muscles. See Muscles. 
 
 Adipose tissue, 175. 
 
 Alee of sphenoid bone, lesser, 37. 
 
 greater, 37. 
 
 vespertilionis, 475. 
 
 Alimentary canal, 322. 
 
 appendages of, 384. 
 
 coats of, 322. 
 
 direction and situation of, 323. 
 
 divisions of, 322. 
 
 —————— dimensions of, 323. 
 
 form of, 323. 
 
 • membranes of, 323. 
 
 ' muscular fibres of, 323. 
 
 structure of, 323. 
 
 Alveoli, 53, 58. 
 Amphiarthroses, 113. 
 
 ■ characters, ligaments, and motions, 113 
 
 Ampulla of semicircular canals, 677. 
 
 Amygdala, 333. See Tonsils. 
 Amygdaloid fossa, 331. 
 Anastomoses of arteries, 496. 
 
 lymphatics, 614. 
 
 nerves, 762. 
 
 veins, 574. 
 
 Anastomotic artery, brachial, 544. 
 
 femoral, 565. 
 
 ATUitomy, objects and divisions of, 1, 2. 
 descriptive, 1. 
 
 general, 1, 2. 
 
 Anfractuosities. See Cerebrum. 
 
 Angeiology, 479, 
 
 Angle, sacro-vertebral, 26. 
 
 of the femur, 93. 
 
 facial, of Camper, 45. 
 
 occipital, of Daubenton, 45. 
 
 of the jaw, 58. 
 
 changes daring growth, 59. 
 
 of the pubes, 89. 
 
 Angles of bones, 9. 
 AtucIc joint, 168. 
 
 ligaments of, 169. 
 
 Ankle. See Tarsus. 
 
 Annular ligaments. See Ligament!. 
 
 Anti-helix, and its fossa, 666. 
 
 tragus, 666. 
 
 Antrum Highmori, 52. 
 
 pylori, 355. 
 
 Anus, 380. 
 
 muscles of, 380. 
 
 structure of, 380 
 
 Aorta. See Arteries. 
 Aponeurology, 294. 
 Aponeuroses in general, 294. 
 classification of, 294. 
 
 containing, 294. 
 
 definition of, 294. 
 
 functions of, 296. 
 
 insertion of, 294. 
 
 structure of, 296. 
 
 ■ tensor muscles of, 295. 
 Aponeuroses in particular, 297. 
 ————— abdominal anterior, 300. 
 
 layers of, 301. 
 
 Aponeuroses, cervical, superficial, 299. 
 
 cephalo-pharyngeal, 346. 
 
 costo-clavicular, 137. 
 
 of the cranium, 299. 
 
 cremasteric, 302. 
 
 cribriform, 309. 
 
 deltoid, 315. 
 
 dorsal of the foot, 314. 
 
 metacarpus, 318 
 
 interosseous, of foot, 314. 
 hand, 318. 
 
 ■ epicranial, 298. 
 
 ■ external oblique, 301 
 
 ■ of the eyehds, 647. 
 face, 299. 
 
 ■ femoral, 309. 
 
 septa of, 310. 
 
 sheath for vessels, 310. 
 
 ' muscles, 311. 
 
 posterior, 305. 
 superficial, 297. 
 
 brachial, 316. 
 buccinator, 298. 
 buccinato-pharyngeal, 235. 
 cervical, deep, 299. 
 
 - of the fore-arm, 316. 
 -gluteal, 311. 
 
 - hypothenar, 319. 
 
 • iliac, 306. 
 
 • infra-spinous, 315. 
 
 • intercostal, 360. 
 
 ■ inter-muscular of thigh, 310. 
 
 • of internal oblique, 304. 
 ■of the leg, 312. 
 
 lower extremity, 309. 
 
 superficial, 297. 
 
 ■ lumbar, or posterior abdominal, 30i6. 
 
 • lumbo-iliac, 306. 
 
 - masseteric, 298. 
 
 - of the neck, 299. 
 
 - obturator, 309. 
 
 - occipito-frontal, 298. 
 
 - occipito-pharyngeal, 346. 
 -palmar, 319. 
 -parotid, 298. 
 
 ■ pedal, 314. 
 
 ■ pelvic lateral, 308. 
 superior, 308. 
 
 ■ of the pelvis, 306. 
 proper, 307. 
 
 • perineal, deep, 307. 
 superficial, 306. 
 
 ■ petro-pharyngeal, 346. 
 
 ■ of the pharynx, 346. 
 
 ' plantar, external, 314. 
 
 internal, 314. 
 
 ■ interosseous, 315. 
 middle, 314. 
 
 — prasvertebral, 299. 
 
 — of the quadratus lumborum, 306. 
 
 — recto-vesical, 308. 
 
 — of the serratus posticus, 300. 
 shoulder, 315. 
 
 • spermatic cord, 304. 
 
 sub-peritoneal, 305. 
 
 sub-scapular, 315. 
 
 superficial, 2i97. 
 
 of abdomen, 297. 
 
 supra-clavicular, 299. 
 
 supra-spinous, 315. 
 
 temporal, 298. 
 
 thenar, 319. 
 
 of the thorax, 300. 
 
 of transversalis, 305. 
 
 of the upper extremity, 316. 
 
 superficial, 297. 
 
 ■ of velum palati, 346. 
 - vertebral, 205. 
 
 ■ vesical, 309. 
 
 Aponeurotic sheaths for muscles, 296. 
 tendons, 296. 
 vessels, 296. 
 
 Apparatus, hyoid, 109. 
 Apparatttses of human body, general view of, 3, 4. 
 Appendices epiploicse, 372. 
 Appendix, ensiform, or xiphoid, 65. 
 vermiformis, 373 
 
876 
 
 INDEX. 
 
 Appendix, vermiformis, development of, 384. 
 
 structure of, 373. 
 
 Aqueductus Fallopii, 43, 839. 
 
 vestibuli, 44. 
 
 cochlea;, 44. 
 
 Sylvii, 719, 742 
 
 Aqueous humour, 65.5. 
 
 membrane of, 655. 
 
 Arachnoid, 687. 
 
 canal (of Bichat), 687. 
 
 cranial portion of, ©7. 
 
 internal, 691. 
 
 loose, 690. 
 
 membrane of eye, 656 (note). 
 
 spinal portion of, 690. 
 
 uses of, 692. 
 
 Arbor vitas uterina, 465. 
 Arch, aortic, 502. 
 
 of colon, 374. 
 
 crural, 302. 
 
 femoral, 302. 
 
 gluteal, 3U. 
 
 orbital, 36. 
 
 palatine, 329. 
 
 pubic, 89. 
 
 sub-pubic, 307. 
 
 ■ zygomatic, 61. 
 
 Arches, alveolar, 174. 
 
 dental, 174. 
 
 zygomatic, 61. 
 
 Arm, bone of, 78. 
 
 compared -with thi^h bone, 107. 
 
 Arteries in general, 496. 
 
 anastomoses of, 496. 
 
 branches of, 497. 
 
 coat of, external or cellular, 498. 
 
 internal, 498. 
 
 . middle, proper, or elastic, 498. 
 
 — ..— - — course or direction of, 496. 
 
 definition of, 496 
 
 division of, 496. 
 
 form of, 496. 
 
 nerves of, 497. 
 
 nomenclature of, 495. 
 
 origin of, 496. 
 
 preparation of, 497. 
 
 relations with other parts, 497. 
 
 retia mirabilia of, 496. 
 
 satellite muscles of, 497. 
 
 sheaths for, 499. 
 
 structure of, 499. 
 
 termination of, 498. 
 
 varieties of, 496. 
 
 vasa vasorum of, 499. 
 
 venae comites of, 497. 
 
 vessels of, 499. 
 
 Artery or Arteries in particular, 497. 
 
 of particular organs or tissues. 
 
 gans, Sec. 
 acromial, descending, 542. 
 
 supra-scapular, 538. 
 
 transverse, 542. 
 
 acromio-thoracic, 542. 
 
 of ala nasi, 518. 
 
 alar thoracic, 542. 
 
 alveolar, 524. 
 
 anastomotic, brachial, 544. 
 
 - great, of thigh, 564. 
 
 See those or- 
 
 angular, of face, 517, 529 
 aorta, 501. 
 
 abdominal, 503. 
 
 arch of, 502. 
 
 ascending, 503. 
 
 branches of, 503 
 
 descending, 503. 
 
 sinuses of, 501. 
 
 thoracic, 503. 
 
 valves of, 486. 
 
 arising from abdominal aorta, 606. 
 
 '■ — arch of aorta, 513. 
 
 varieties of, 513. 
 
 origin of aorta, 504. 
 termination of aorta, 552. 
 thoracic aorta, 505. 
 
 articular, of hip, 564. 
 
 knee, inferior, 565. 
 
 middle, or azyg»s, 565. 
 
 superior, 565. 
 
 - ascending cervical, 538 
 pharyngeal, 520. 
 
 Arteri; auricalar, anterior, 521. 
 posterior, 519. 
 
 aiiliary, 531, 542. 
 axis, coeliac, 507. 
 
 thyroid, 535. 
 
 azygos, or middle articular of knee 565. 
 basilar, 534. 
 brachial, 543. 
 brachio-cephalic, 531. 
 bronchial, 505. 
 
 ' distribution of, 421. 
 
 buccal, 524. 
 of bulb, 558. 
 calcaneal, external, 570. 
 inferior, 571 
 
 capsular, inferior, 513. 
 
 middle, 513. 
 
 superior, 513. 
 
 cardiac, 503. 
 
 carotid, common, left and right, 514. 
 
 general distribution of, 530. 
 
 ■ external or facial, 515. 
 - internal, 525. 
 • superficial, 515. 
 
 carpal, radial, anterior, 546. 
 
 posterior dorsal, 546. 
 
 ulnar, anterior, 549. 
 
 posterior dorsal, 549. 
 
 central of retina, 597, 665. 
 cerebellar, inferior, anterior, 534. 
 posterior, 534. 
 
 ■ superior, 635. 
 
 cerebral, anterior. 529. 
 
 ■ communicating anterior, 529. 
 
 • posterior, 529. 
 
 middle, 530. 
 
 posterior, 537. 
 
 cervical, ascending, 538. 
 
 deep, 540. 
 
 princeps, 519, 
 
 superficial, 539. 
 
 cervico-spinal, 538. 
 choroid, anterior, 530. 
 posterior, 536. 
 
 ciliary, anterior, 527. 
 
 middle, or long, 528. 
 
 posterior, or short, 528, 665. 
 
 circle of Willis, 536 
 circumflex, femoral, external, 564. 
 internal, 563. 
 
 iliac, 560. 
 humeral, anterior, 543. 
 posterior, 543. 
 
 of clitoris, 558. 
 coccygeal, 552. 
 coeliac (axis), 507. 
 colic, left, 511. 
 
 right, 510. 
 
 collateral, of fingers, radial, 547. 
 ulnar, 549. 
 
 humeral, external, 543. 
 
 internal, 543. 
 
 of knee. See Articular. 
 
 of toes, from external plantar, 57 
 
 internal plantar, 572 
 
 comites. See Satellite. 
 communicating, cerebral, anterior, 529. 
 
 posterior, 529, 535 
 
 palmar, 548. 
 plantar, 572. 
 of Willis, 529. 
 
 coronary of heart, left or anterior, 504. 
 
 right or posterior, 504. 
 
 • lips, inferior, 5l7. 
 superior, 518. 
 
 • stomach, 507. 
 
 of corpus callosum, 529. 
 
 cavemosum, 558. 
 
 cremasteric, 560. 
 
 crural, 560. 
 
 cystic, 508. 
 
 deep, brachial or humeral, 544. 
 
 cervical, 540. 
 
 femoral, 563. 
 
 temporal, 522. 
 
 deferential, 452. 
 
 dental, anterior, 524. 
 
 inferior, 523. 
 
 superior, 524. 
 
 ■ diaphragmatic, inferior, 506. 
 
INDEX. 
 
 877 
 
 Artery, diaphragmatic, superior, 539. 
 
 digital, collateral, radial, 547 
 
 ulnar, 549. 
 
 of foot, 572. 
 
 dorsal, carpal, radial, 547. 
 ulnar, 549. 
 
 ■ of foot, 568. 
 — index finger, 548. 
 metacarpal, radial, 547. 
 ulnar, 549. 
 
 • metatarsal, 569. 
 
 • of nose, 529. 
 
 — penis, 558. 
 
 — scapula, 538. 
 
 — tarsus, 572. 
 
 — thumb, 548. 
 
 — toe, great, 572. 
 tongue, 518. 
 
 - dorsi-spinal, of inferior intercostals, 507. 
 
 superior intercostals, 540 
 
 - emulgent, 512. 
 
 ■ epigastric, 559. 
 Superficial, 562. 
 
 ■ epiploic, 510. 
 
 ■ ethmoidal, anterior, 528. 
 posterior, 528. • 
 
 ■ facial, 517. 
 
 • femoral, 559. 
 
 deep, 563. 
 
 Artery, magna pollicis, of hand, 547. 
 
 malar cutaneous, 521. 
 
 malleolar, externa], 567. 
 
 internal, 567. 
 
 mammary, external, 542. 
 
 internal, 539. 
 
 ■ masseteric, 521, 523. 
 ' mastoid, 520. 
 posterior, 519. 
 
 maxillary, external, 517. 
 
 internal, 522. 
 
 general distribution of, 525. 
 
 of median nerve, 549. 
 
 mediastinal, 540. 
 
 medullary, 506. 
 
 meningeal, anterior, 528. 
 
 middle or great, 522. 
 
 of ascending pharyngeal, 620. 
 
 posterior, 519, 514. 
 
 small, 523. 
 
 - of fissure of Sylvius, 529. 
 -of fraenum lingua;, 519. 
 
 - frontal, 529. 
 
 of temporal, 520. 
 
 • gastric, inferior, 509. 
 
 superior, 509. 
 
 ■ gastro-duodenal, 508. 
 
 epiploic, left, 509. 
 
 right, 508. 
 
 hepatic, 508. 
 
 • gluteal, inferior, 556. 
 superior, 556. 
 
 • hemorrhoidal, 557. 
 
 inferior, 557. 
 
 middle, 554. 
 
 -superior, 511. 
 
 - helicine, 456. 
 
 ■ hepatic, 508. 
 
 — in the liver, 391, 392. 
 
 ■ humeral, 543. 
 
 deep, inferior, 544. 
 
 deep, superior, 544. 
 
 ■hyoid, of lingual, 518. 
 
 superior thyroid, 515 (note). 
 
 • hjrpogastric, 553. 
 
 • iliac, common, 552. 
 
 external, 559. 
 
 internal, 553. 
 
 general distribution of, 558. 
 
 — mental, 523. 
 -- mesenteric, inferior, 511. 
 • superior, 510. 
 
 metacarpal, radial, 546. 
 ■ ulnar, 549. 
 
 • metatarsal, 569. 
 ■ muscular, of orbit, 528. 
 thigh, 562. 
 
 • musculo-phrenic, 540. 
 for mylo-hyoideus, 523. 
 nasal, 528. 
 
 • dorsal, 529. 
 
 -- lateral, 518. 
 — of pterygo-palatine, 524. 
 of septum, 518. 
 
 nutritious, of femur, 542. 
 
 fibula, 570. 
 humerus, 545. 
 tibia, 569. 
 
 ■ obturator, 554. 
 
 • occipital, 519. 
 
 • (Esophageal, 505. 
 
 • omphalo-mesenteric, 511. 
 ophthalmic, 525. 
 
 ' orbital, of temporal, 521. 
 ovarian, 512. 
 palatine, inferior, 517. 
 — superior, 524. 
 
 ■ ileo-colic, 511. 
 
 ■ ilio-lumbar, 555. 
 
 ■ incisory, inferior, 523. 
 superior, 524. 
 
 • infra-orbital, 524. 
 
 or sub-scapular, 542. 
 
 spinous, 542. 
 
 ' innominate, 531. 
 
 ■ intercostals, anterior, 540. 
 
 aortic or inferior, 505. 
 
 superior, 540. 
 
 • interlobular, of liver, 391. 
 
 • interosseous, dorsal, of foot, 569. 
 — hand, 547. 
 
 of forearm, anterior, 548. 
 
 posterior, 549. 
 
 palmar, 547 
 
 ■ plantar, 572. 
 
 recurrent, of forearm, 549. 
 
 ■ of the intestines, great, 511. 
 ■ small, 510. 
 
 intra-spinal, 534. 
 
 ischiatic, 556. 
 
 of labia pudendi, 558. 
 
 labial, inferior, 517. 
 
 superior, 517. 
 
 lachrymal, 526. 
 
 laryngeal, inferior, 516. 
 
 superior, 516. 
 
 lingual, 518. 
 
 lumbar, 506. 
 
 magna pollicis, of foot, 572. 
 
 ■ palmar, deep, 546. 
 
 ' palmar, interosseous, 548. 
 
 superficial, 547. 
 
 ■ recurrent, 547. 
 
 • palpebral, inferior, 528. 
 superior, 528. 
 
 • pancreatic, great (from splenic), 509. 
 small (from mesenteric), 510, 
 
 • pancreatico-duodenal, 508. 
 
 ■ parietal, 519, 521. 
 
 ■ parotid, 520. 
 
 • of penis, 558. 
 dorsal, 558. 
 
 ' perforating, of forearm, 549 
 
 palmar, 548. 
 
 peroneal, 570. 
 
 plantar, anterior and posterior, 569. 
 
 572. 
 • of thigh, 564. 
 
 • pericardiac, 495. 
 
 perinaeal, superficial, 557. 
 transverse, 557. 
 
 peroneal, 570. 
 
 anterior, 570. 
 
 • perforating, 570. 
 
 ■ pharyngeal, ascending or inferior, 520. 
 
 ■ pharyngo-meningeal, 520. 
 • phrenic, inferior, 507. 
 
 ■ superior, 539. 
 
 ■ for phrenic nerve, 539. 
 
 ■ plantar, external, 571. 
 ' internal, 571. 
 
 ■ popliteal, 564 
 
 • prevertebral, 520. 
 
 • princeps cervicis, 519. 
 — pollicis, 547. 
 
 profunda cervicis, 549. 
 
 femoris, 563. 
 
 humeri, inferior, 545. 
 
 superior, 544. 
 
 pterygoid, of facial, 517. 
 internal maxillary, 523. 
 
INDEX. 
 
 Artery, pterygo- palatine, 524. "^tffl^ 
 
 pudic, external inferior; 562.'' 
 
 superior, 56?. 
 
 internal, 557. 
 
 — in the female, 558. 
 
 pulmonary, 500. 
 
 '~ left branch of, 501. 
 
 right branch of, 501. 
 
 ' distribution of, 431. 
 
 pyloric, inferior, 508. 
 
 superior, 508. 
 
 radial, 546. 
 
 ■ collateral of fingers, 547. 
 
 recurrent, 540. 
 
 radialis indicis, 548. 
 
 radio-cubital, 549. 
 
 palmar, 547. 
 
 ranine, 518. 
 
 of receptaculum, 525. 
 
 — recurrent interosseous, of forearm, 549. 
 
 palmar, 547. 
 
 radial, 546. 
 
 tibial, anterior, 668. 
 
 internal, 569. 
 
 ' ulnar, anterior, 549. 
 ' posterior, 549. 
 
 ■ renal, 512. 
 distribution of, 439. 
 
 ■ of retina, central, 527. 
 
 ■ sacral, lateral inferior, 556. 
 superior, 556. 
 
 middle or anterior, 552. 
 
 satellite of median nerve, 549. 
 
 phrenic, 540. 
 
 sciatic, 556. 
 
 ulnar, 548. 
 
 • scapular, inferior, 542. 
 
 posterior, 538. 
 
 ■ superior, 538. 
 
 — sciatic, 556. 
 
 — for sciatic nerve, 556. 
 scrotal, 557. 
 
 — of septum of nose, 518. 
 ' ventricles of heart, 504. 
 
 — short, of stomach, 511. 
 
 — sigmoid, 511. 
 spermatic, 511. 
 
 — spheno-palatine, 524. 
 spinous, 522. 
 
 — spinal, 534, 609. 
 anterior, 534. 
 
 ■ general distribution of, 609. 
 
 Artery, thoracic htuneral, or deltoid, of acromio-tbora 
 cic, 542. 
 
 inferior, 542. 
 
 long, 542. 
 
 - thymic, 540. 
 
 - thyroid axis, 537. 
 
 inferior, 537. 
 
 middle, 515. 
 
 of Neubauer, 537. 
 
 superior, 516. 
 
 • tibial, anterior, 567. 
 
 posterior, 570. 
 
 recurrent, 567. 
 
 • tibio-peroneal, 569. 
 ' tonsillar, 521. 
 
 ■ transverse, of perineum, 556. 
 
 neck, 539. 
 
 face, 521. 
 
 • shoulder, 538. 
 
 ■ tympanic, 522. 
 
 • ulnar, 548. 
 
 collateral, 543. 
 
 of fingers, 649. 
 
 recurrent, anterior, 549. 
 
 posterior, 549. 
 
 ' umbilical, 553. 
 
 • uterine, 554. 
 
 ■ vaginal, 554. 
 
 • of liver, 392. 
 
 ■ vasa brevia, of stomach, 609. 
 
 • for vertebrae, 504. 
 
 • vertebral, 533. 
 
 • vesical, 553. 
 
 ■ vidian, 524. 
 
 Arthrodia, 114. 
 
 characters, ligaments, and motions, 115 
 Arthrology, 111. 
 Articular surfaces, in general, 111. 
 
 - of particular articulations, 
 those articulations. 
 
 Se« 
 
 posterior, 534. 
 
 re-enforcing, cervical, 534. 
 
 lumbar, 504. 
 
 thoracic, 504. 
 
 of spinal cord, 504, 634. 
 
 — ^ — splenic, 509. 
 
 in spleen, 405. 
 
 for sterno-mastoid, 516, 519. 
 
 stylo-mastoid, 519. 
 
 sub-clavian, left and right, 531. 
 
 sub-diaphragmatic, 504. 
 
 sub-lingual, 518. 
 
 ■ for sub- maxillary gland, 517. 
 
 —— — sub-mental, 517. 
 — — — sub-scapular, 542. 
 
 superciliary, 527. 
 
 superficial, of neck, 546. 
 
 palm, 547. 
 
 perineum, 556. 
 
 superficialis voIk, 547. 
 
 supra-orbital, 527. 
 
 renal, inferior, 512. 
 
 middle, 512. 
 
 ■ superior, 512. 
 
 . sural, 565. 
 
 scapular, 538. 
 ' spinous, 538. 
 
 tarsal, dorsal, or external, 568. 
 
 internal, 568. 
 
 temporal, 521. 
 
 ■ deep anterior, 524 
 
 middle, 521. 
 
 • posterior, 523. 
 
 superficial, 521. 
 
 testicular, 511. 
 
 ■ distribution of, 536. 
 
 thoracic acromial, 542. 
 alar, 542 (note). 
 
 • borders, 112, 
 
 structure of, 177. 
 
 ■ cartilages. 111. 
 structure of, 177. 
 
 ■ cavities, 10. 
 
 supplementary, 128. 
 
 processes, or eminences, 10. 
 
 of Tertebrse, 20, 22. 
 
 — union of, 116. 
 
 Articular arteries. See Arteries. 
 
 nerves. See Nerves. 
 
 Articulations in general, 111-116. 
 
 ■ amphiarthroses, 113. 
 
 arthrodia, 1 14. 
 
 classification of, 113. 
 
 condylarthrosis, 114. 
 
 definition of. 111. 
 
 diarthroses, 113. 
 
 enarthrosis, 114. 
 
 ginglymus, 114. 
 
 gomphosis, 114. 
 
 harmonia, 114. 
 
 — ■ immovable, 113. 
 — - meningoses, 113 
 
 mixed, 113. 
 
 movable, 113. 
 
 movements of, 113. 
 
 — by mutual reception, 113. 
 schindylesis, 114. 
 
 — sutures, 114. 
 
 — symphyses, 114. 
 
 — synarthroses, 114. 
 
 — synchondroses, 113. 
 
 — syneuroses, 113. 
 
 — syssarcoses, 113. 
 
 — trochlear, 114. 
 • trochoid, 114. 
 
 Articulations in particular, 113. 
 
 acromio-clavicular, 135. 
 
 mechanism of, 136. 
 
 ' of ankle. See Tibio-tarsal, 
 ■ astragalo-scaphoid, 171. 
 ' of astragalus with os calcis, 170. 
 ■ movements of, 153. 
 
 atlanto-axoid, 117. 
 
 ' mechanism of, 124. 
 
 'odontoid, 117. 
 
 ' of atlas and axis, 117. 
 
 articular processes of, 
 
 118 
 
INDEX. 
 
 879 
 
 Arttculations, calcaneo-cuboid, 173. 
 
 carpal, in general, 147. 
 
 . — mechanism of, 148. 
 
 of each row, 147. 
 
 of two rows together, 147. 
 
 ■ pisiform and cuneiform, 147. 
 
 ■ carpo- metacarpal, in general, 149 
 
 mechanism of, 150. 
 
 first, 149. 
 
 mechanism of, 150. 
 
 fifth, 150. 
 
 mechanism of, 150. 
 
 second, third, & fourth, 
 
 150. 
 • carpo-metacarpal, of the thumb, 150. 
 ■ mechanism of, 150. 
 
 ■ chondro-costal, 132. 
 
 • sternal, in general, 131. 
 
 in particular, 131. 
 
 movements of, 133. 
 
 ■ coccygeal, 120. 
 
 ■ condyloid, of occiput and atlas, 116. 
 • coraco-clavicular, 135. 
 
 • mechanism of, 136. 
 
 ' of the costal cartilages, 132. 
 
 • movements of, 132. 
 
 ■ costo-clavicular, 138. 
 mechanism of, 138. 
 
 ■ costo-transverse, 131. 
 vertebral, 131, 
 
 in general, 131. 
 
 in particular, 131. 
 
 movements of, 131. 
 
 proper, 131. 
 
 of first rib, 131. 
 
 of eleventh and twelfth 
 
 ribs, 131. 
 
 • coxo-femoral, 159. 
 movements of, 161. 
 
 • cranial, 124. 
 ■ mechanism of, 125. 
 
 — cranio-vertebral, 120. 
 mechanism of, 123. 
 
 — crico-arytenoid, 426. 
 thyroid 426. 
 
 — of the elbow, 143. 
 
 — of the extremities, upper, 135. 
 lower, 153. 
 
 — of the face, 126. 
 
 — of the fingers, in general, 151. 
 
 — of the head, with vertebral column. 
 
 Cranio-vertebral. 
 
 — of the hip. See Coxo-femoral. 
 
 — humero-cubital, 141. 
 • movements of, 142. 
 
 ■ of jaw, lower. See Temporo-maxillary, 
 
 128. 
 
 upper, 126. 
 
 with cranium, 126. 
 
 • of the knee, 162. 
 mechanism of, 166. 
 
 • of larynx, 425. 
 
 ■ of metacarpal bones, carpal ends of, 148. 
 
 digital ends of, 149. 
 
 with carpus, 149. 
 
 • metacarpo-phalangal, 151. 
 movements of, 152. 
 
 • of metacarpus in general, 148. 
 
 ■ of metatarsal bones, tarsal ends of, 175. 
 digital ends of, 175. 
 
 ' mechanism of, 175. 
 
 ■ metatarso-phalangal, 175. 
 movements of, 177. 
 
 ■ occipito-atlantoid, 116. 
 • mechanism of, 122. 
 
 axoid, 117. 
 
 ■ peroneo-tibial, inferior, 167. 
 
 middle, 168. 
 
 superior, 168. 
 
 mechanism of, 168. 
 
 ■ of the pelvis, 154. 
 
 mechanism of, 156. 
 
 ' phalangal, of fingers, 153. 
 
 movements of, 153, 
 
 toes, 177 
 
 movements of, 177. 
 
 Articulations, radio-cubital, mechanism of, 144. 
 
 inferior, 142, 
 
 movements of, 144. 
 
 — middle, 143. 
 
 movements of, 143. 
 
 — — superior, 142. 
 
 • movements of, 144. 
 
 • sacro-coccygeal, 120. 
 
 iliac, 154. 
 
 sciatic, 155. 
 
 vertebral, 120, 
 
 • scapulo-humeral, 138. 
 -—- movements of, 139. 
 
 • of the shoulder, 135. 
 
 ■ sterno-clavicular, 136. 
 
 mechanism of, 137. 
 
 ■ syndesmo-odontoid, 117. 
 ' tarsal, in general, 170. 
 
 • mechanism of, 173 
 
 of first row, 171. 
 
 of second row, 171. 
 
 movements of, 173. 
 
 of two rows together, 172. 
 
 movements of, 173. 
 
 -- tarso-metatarsal, in general, 174. 
 
 movements of, 173. 
 
 in particular, 173. 
 
 — temporo-maxillary, 128. 
 
 • mechanism of, 129, 
 
 • of the thorax, 130. 
 
 ' mechanism of, 132. 
 ■ movements of, 134. 
 
 ■ thyro-hyoid, 425. 
 
 tibio-tarsal, 168. 
 
 mechanism of, 169, 170. 
 
 tracheo-cricoid, 426, 
 
 of the vertebral column, 115. 
 
 mechanism 
 
 121-123. 
 movements 
 
 122. 
 
 of, 
 
 ■ of the vertebris with each other, 115. 
 
 bodies of, 115. 
 
 articular processes of, 116. 
 
 laminae of, 116. 
 
 spinous processes of, 116. 
 
 -^— ^— — — peculiar, 1 16. 
 
 ■ of the wrist, 145. See Radio-carpal 
 
 Astragalus, 100, 
 
 Atlas, 23, 
 
 Auditory process, 44. 
 
 meatus, internal, 44. 
 
 external, 44, 
 
 nerve. See Nerve, portio molHt. 
 Auricle or auricula of ear, 666. See Ear. 
 Auricles of heart. See Heart. 
 Auricular surface of os coxse, 91. 
 Axis (vertebra), 24, 
 
 Basilar process, 34, 
 groove, 35. 
 Bicipital groove, 78, 
 
 tuberosity, 81, 
 
 Bi-parietal suture, 46, 
 Biventer cervicis, 205, 
 
 maxiOae inferioris, 245, 
 
 Bladder, 440. 
 
 bas-fond of, 442. 
 coats of, 442. 
 development of, 443. 
 functions of, 444. 
 fundus, inferior, 442, 
 
 superior, or summit. 443. 
 
 — ligaments of, anterior, 441, 
 ■ posterior, 441. 
 
 sacculated and fasciculated, 444. 
 
 sphincter of, 443. 
 
 structure of, 443. 
 
 trigone of, 443. 
 
 uvula of, 443. 
 
 ■ vessels and nerves, 444, 
 
 •j)ubic, 155, 
 
 ■ radio-carpal, 145, 
 
 • movements of, 145 
 
 - cubital, 142. 
 
 Bones in general, 5-18. 
 
 - arteries of, three kinds, 14, 15. 
 
 - asymmetrical, 8. 
 
 - broad or flat, 9. 
 
 diploe of, 13. 
 
 ossification of, 17. 
 
 structure, internal, 13. 
 
 tables of, 13. 
 
 vitreousi 35. 
 
880 
 
 INDEX. 
 
 flonei, eavities of, 9, 10. 
 
 '■ articular, 10. 
 
 alveolar, 10. 
 
 cotyloid, 10. 
 
 glenoid, 10. 
 
 trochleae, 10 
 
 non-articular, 10. 
 
 canals or conduits, iO. 
 
 fosse, 10. 
 
 furrows, grooves, or chan- 
 nels, 10. 
 
 notches, 10. 
 
 sinuses or cells, 10. 
 
 Bones, coronal, 35, 
 
 costae. See Ribs. 
 of cranium, 33. 
 cubital, 79. 
 cuboid, 101. 
 cuneiform, carpal, 83. 
 
 tarsal, external, 102. 
 
 internal, 102. 
 
 middle, 103. 
 
 ossification of, 17. 
 
 — changes in, after maturity, 18. 
 
 — chemical composition of, 14. 
 -- description of, mode of, 11. 
 
 — development of, 15. 
 
 cartilaginous stage, 15. 
 
 — mucous stage, 15. 
 
 osseous stage, 16. 
 
 symmetry of, 17. 
 
 ■ direction of, absolute and relative, 7. 
 • eminences of, 9. 
 
 articular, 9. 
 
 condyles, 9 
 
 ■ heads and necks, 9. 
 
 -non-articular, 9 
 
 apophyses, 9. 
 
 epiphyses, 9. 
 
 - marginal, 18, 
 
 -ossification of, 16. 
 
 • lines and crests, 9, 
 
 ■ mammillary process- 
 
 es, 9. 
 
 ■ processes, 10. 
 
 ■ prominences, 9, 
 
 • spines or spinous pro- 
 
 cesses, 9. 
 
 • tuberosities, 9. 
 
 — foramina of, 11. 
 
 ~ growth, mode of, 18. 
 
 -- long, 8. 
 
 extremities and shafts of, 9. 
 
 marrow or medulla of, 10. 
 
 medullary canal of, 10. 
 
 membrane of, 13. 
 
 -structure of, internal, 10. 
 •ossification of, 16. 
 
 ~ nerves of, 14. 
 
 nomenclature of, 6. 
 
 number of, 6. 
 
 • nutrition of, 18. 
 
 ossific points of, 16. 
 
 ossification of, 16, 17. 
 
 eminences and cavities of, 17. 
 
 ■ three kinds of, 17. 
 
 regions of, 9. 
 
 shape and symmetry of, 8. 
 
 short, 9. 
 
 ossification of, 18. 
 
 structure, internal, of, IS. 
 
 situation of, general, 6. 
 
 size, weight, and density of, 7. 
 
 structure of, internal, 13. 
 
 -microscopic, 11. 
 
 — of ear, 673. 
 
 — epactal, 50. 
 
 — ethmoid, 40. 
 development of, 41. 
 
 — efface, 51. 
 
 — femur, 93. 
 
 development of, 95 
 
 — fibula, 98. 
 
 development of, 99. 
 
 — of fingers. See Phalanges. 
 
 — of foot, 99. 
 
 — of forearm, 79, 80. 
 
 — frontal, 35. 
 development of, 36. 
 
 •of hand, 82. 
 
 ■ of haunch, 89. 
 
 ■ humerus, 78. 
 development of, 79. 
 
 ■ hyoid, 109. 
 development of, 111. 
 
 ■ ilium, 89. 
 
 • incus, 674. 
 
 ■ ischium, 89. 
 
 ■ of jaw, lower, 57. 
 upper, 61. 
 
 jugal, 54. 
 
 lachrymal, 56. 
 
 development of, 56. 
 
 • of leg, 96. 
 
 • lenticular, 674. 
 
 • malar, 54. 
 - development of, 55. 
 
 malleus, 673. 
 
 maxillary, inferior, 57. 
 
 development of, 58 
 
 superior, 51. 
 
 • development of, 53. 
 
 substance of, areolar, 11. 
 
 cancellated, or spongy, 11. 
 
 ■ compact, 11. 
 
 reticulated, 11, 13. 
 
 surfaces, angles, and bordeni of, 8, 
 
 symmetrical, 8. 
 
 torsion of, 99. 
 
 veins and lymphatics of, 14. 
 
 Bones in particular, 18-111. 
 
 of arm, 78. 
 
 astragalus, 100. 
 
 atlas, 23. 
 
 development of, 31. 
 
 axis, 24. 
 
 - development of, 31. 
 
 — calcaneum, 100. 
 
 — of carpus or wrist, 82. 
 
 development of, 84. 
 
 first row of, 83. 
 
 second row of, 83. 
 
 — clavicle, 74. 
 development of, 75. 
 
 coccyx, 20. 
 
 development oi, 31. 
 
 ■ of metacarpus, 84. 
 
 development of, 85. 
 
 : first, 85. 
 
 second, third, and fourth, 85. 
 
 fifth, 85. 
 
 ■ of metatarsus, 103. 
 
 development of, 104. 
 
 first, 103. 
 
 second, third, and fourth, 103 
 
 ■ fifth, 103. 
 
 • nasal, 55. 
 development of, 56. 
 
 • navicular, of carpus, 83. 
 > tarsus, 101. 
 
 • occipital, 33. 
 
 development of, 34. 
 
 • orbicular, 674. 
 
 • OS calcis, 100. 
 
 carinse, 33. 
 
 hyoides, 110. 
 
 iimominatum, I 
 
 • development of, 90. 
 
 - magnum, 83. 
 
 • planum, 40. 
 
 • prorae, and os puppis, 33. 
 quadratum, 53 
 
 ■ unguis, 55 
 
 - ossa triquetra, or Wormiana, 50 
 
 - ossicula auditfis, 673. 
 • palate, 63. 
 
 development of, 54. 
 
 ■ parietal, 41. 
 
 development of, 42. 
 
 ' patella, 95. 
 
 development of, 96. 
 
 • of pelvis, 87. 
 
 • perone. See Fibula. 
 
 ■ phalanges of fingers, 86. 
 
 • development of, 87 
 
 ■ pisiform, 83. 
 
 ■ of pubes, 90. 
 
 ■ radius. 81. 
 
 ■ toes, 104. 
 
 - development of, 104 
 
JXBBX 
 
 881 
 
 BoHtM, radius, development of, 89. 
 
 ribs, 67. 
 
 — ^-^— ^ development of, 68. 
 
 false and true, 67. 
 
 rotula, 95. 
 
 sacrum, 26. 
 
 - development of^ SS. 
 
 scaphoid of carpus, 83. 
 tarsus, 101. 
 
 ' scapula, 75. 
 
 ' development of, 75. 
 
 - semilunar, 83. 
 sesamoid, 96. 
 
 of foot, 176. 
 
 of gastrocnemius, 165. 
 
 of hand, 153. 
 
 ' of knee or patella, 06. 
 
 of shoulder, 73. 
 
 sphenoid, 36. 
 
 development of^ 38. 
 
 - spheno-occipital, 36. 
 
 - spongy. See Turbinaitd. 
 
 - sternum, 64. 
 
 development of, 65. 
 
 - styloid, 43. 
 
 - of tarsus, 99. 
 
 development of, 103. 
 
 first row of, 100. 
 
 second row of, 101. 
 
 temporal, 42. 
 
 development of, 44. 
 
 mastoid portion of, 43. 
 
 petrous portion of, 43. 
 
 squamous portion of, 43. 
 
 Condi, for anterior muscle of malleus, 679. 
 
 — arachnoid, of Bichat, 978. 
 
 — carotid, 43. 
 
 — for chorda tympani, 67S. 
 
 — crural, 310. 
 
 — dental, inferior, 50 
 
 — of Fontana, 656. 
 
 — godronn6, 661. 
 
 — hyaloid, 661. 
 
 — incisive, 52. 
 
 — infra-orbital, 51. 
 
 — inguinal, 306. 
 
 — for internal muscle of malleus, 43, 679. 
 
 — of Jacobson, 671. 
 
 — maxillary, superior, 51. 
 inferior, 60. 
 
 — medullary of long bones, 13. 
 
 — nasal, 653. 
 
 — of Nuck, 465. 
 
 — palatine, anterior, 53. 
 posterior, M. 
 
 • of thigh, 93. 
 
 • of thorax, 64. 
 ' tibia, 96. 
 
 development of, 98 
 
 ' of toes. See Phalanges. 
 
 ■ trapezium, 63. 
 
 ■ trapezoid, 83. 
 
 ' turbinated, ethmoidal, 41. 
 
 inferior, 56. 
 
 ' development of, 56. 
 
 middle, 41. 
 sphenoidal, 37. 
 superior, 41. 
 
 tympanic, 45. 
 
 ulna, 79. 
 
 development of, 81. 
 
 unciform, 83. 
 
 of vertebral column. See Vertebra, Vertebra, 
 
 and Vertebral Column. 
 
 vomer or ploughshare, 57. 
 
 — ' development of, S7. 
 
 Wormian, 50. 
 
 zygomatic, 54. 
 
 Borsa appiattita, 706. 
 
 Brain. See Cerebrum, Cerebellum, IsthmtU, and Me- 
 
 dulla Oblongata. 
 Bronchi, 417. 
 
 structure of, 420. 
 
 Bronchia or bronchial tubes, 418. 
 
 relations of, with lobules, 418. 
 
 structure of, 420. 
 
 Bronchial arteries, 420. 
 
 ultimate distribution, 490 
 
 glands (lymphatic), 430. 
 
 tubes, 418. 
 
 veins, 420. 
 
 ultimate distribution, 430 
 
 mucous membrane, 342. 
 
 characters of, 343. 
 
 fiucco-labial furrow, 326 
 
 Bulbs of fornix, or corpora albicantia, 728. 
 
 Bulbus arteriosus, 494. 
 
 Bursa synovial of tendo Achillis, 283. 
 
 of ligamentum patella, 164. 
 
 over patella, 311. 
 
 Bursa mucosse (so called), 175. 
 
 synovial, 175. 
 
 around eyeball, 649. 
 
 near shoulder joint, 143. 
 
 " hip joint, 161. 
 
 knee joint, 164. 
 
 • sub-cutaneous, 630. 
 
 Calamus scripforius, 703. 
 
 Calcaneum, 100. 
 
 Calcar, 736. 
 
 Canal, alimentary See Alimentary Canal. 
 
 of Petit, 661. 
 
 pterygo- palatine, 38. 
 
 pterygoid, 38. 
 
 sacral, 27. 
 
 for tensor tympani muscle, 43, 87L 
 
 tympanic, 673. 
 
 vertebral, 30. 
 
 vidian, 38. 
 
 of Wirsung, 401. 
 
 zygomatic, 55. 
 Canals of bones, 12. 
 
 dental, superior, 51. 
 
 lachrymal, 652. 
 
 palatine, accessory, 54. 
 
 semicircular, 576. See Semicireuha- Cmak. 
 Canine fossa, 51. 
 Canthi of eyelids, 647. 
 Capitula laryngis, 426. 
 Capitulum costae, 68. 
 
 ligaments. See Ligament 
 
 Capsule of GUsson, 478. 
 lens, 663. 
 
 Capsules, synovial, 1 14. 
 
 of particular joints. 
 
 See those joints. 
 
 supra-renal, 445. See Supra-renal Capsule*. 
 
 atrabiliary, 445. 
 
 Caput coecum coli, 37l 
 
 gallinaginis, 464< 
 Cardia, 442. 
 
 nerves 
 
 Carotid arteries. 
 -— nerves. 
 
 See Nerves. 
 See Arteries. 
 See Nerves. 
 See Arteries. 
 
 Carpal arteries. 
 Carpus, bones of, 82. 
 
 bones of first row of, 83. 
 
 compared with first t 
 
 of tarsus, 108. 
 
 second row of, 83. 
 
 compared with second! 
 
 of tarsus, 108. 
 
 ■ compared with tarsus, 107. 
 ' sheaths for tendons on, 316. 
 
 Cartilage, chemical composition of, 174. 
 
 cricoid, 423. 
 
 of ear, 666. 
 
 ensiform, 65. 
 
 structure of, 174. 
 
 thyroid, 433. 
 
 xiphoid, 65. 
 Cartilages, articular, 111. 
 
 characters of, 111. 
 structure of, 174. 
 
 — chemical composition of, 174. 
 
 ■ arytenoid, 424. 
 
 - costal, 69. 
 
 articulations of, 133. 
 
 ■ falciform, of knee, 162. 
 ' inter-articular, 1 12. 
 structure of, 174. 
 
 temporo-maiillary, 128. 
 
 -^-— ~^>— .-.- acromio-clavicular, 136 
 stemo-clavicular, 137. 
 
 of wrist, 143. 
 
 of knee joint, 168. 
 
 ' inter-osseous, 113. 
 
 • structure of, 174. 
 
 5T 
 
 ■ of larynx, 423. 
 
 ossification of, 435. 
 
 of nose. See Nose. 
 
882 
 
 INDEX. 
 
 Cartilages, semilunar, of knee, 163. 
 
 tarsal, of eyelids, 647. 
 
 Caruncula lachrymalis, 647. 
 
 Carunculx myrtiformes, 468. 
 
 Cauda equina, 770. 
 
 Caudal extremity of helix and antihelix, 667. 
 
 Cavernous body. See Corpus Cavemosum. 
 
 Cavity, coronoid, 80. 
 
 cotyloid, 88. 
 
 digital or ancyroid, 947. 
 
 glenoid, of scapula, 76. 
 
 temporal bone, 43. 
 
 olecranoid, 80. 
 
 of omentum, 478. 
 
 sigmoid, great and lesser, 81. 
 
 supplementary, of temporo-maxiUary articula- 
 tion, 128. 
 
 ' of shoulder joint, 139. 
 
 • trochanteric, 95. 
 
 Cavities, articular, 10. 
 
 supplementary, 128. 
 
 orbital, 62. 
 
 glenoid, of tibia, 97. 
 
 • nou-articular, 11. 
 
 Cells of bones, 11. 
 
 ethmoidal, 42. 
 
 frontal, 36. 
 
 sphenoidal, 39. 
 
 Cellular tissue, 298. 
 
 lymphatics of, 613. 
 
 Central foramen of retina, 661. 
 Centrum ovale minus, 736. 
 
 of Vieussens, 736, 752. 
 
 semicirculare geminum, 746. 
 
 Cerebellar arteries. See Arteries. 
 
 veins. See Veins. 
 
 Cerebellum, 715. 
 
 arbor vitie, lateral and median, 721. 
 
 commissures of, 723. 
 
 comparative anatomy, 724. 
 
 corpus callosum of, 711. 
 
 dentatum or rhomboideum, 721. 
 
 development of, 724. 
 
 falx of, 684. 
 
 fasciculi, converging and diverging, 724. 
 
 fibres of, formative and uniting, 724. 
 
 fissure of, median, 717. 
 
 furrovrs of, 717. 
 
 Gall's views of, 724. 
 
 ganglia of, 721. 
 
 general view of, 724. 
 
 internal structure of, 718. 
 
 examined by hardening, 722. 
 
 • ■ sections, 721. 
 
 water, 722. 
 
 Cerebrum, anfractuosities, uses of, 735. 
 
 arbor vitae of, 750. 
 
 base of, 727. 
 
 lateral regions, 731. 
 
 median excavation of, 727. 
 
 region, 727. 
 
 commissures, 753. See Commissur* 
 
 comparative anatomy of, 757. 
 
 convolutions or gyri, 732. 
 
 of digital cavity, 733. 
 
 inferior surface, 733. 
 
 superior surface, 734. 
 
 internal surface, 733. 
 
 ■ structure of, 755. 
 • uses of, 734. 
 Gall's views of, 754 
 
 • crura of, 723. 
 
 • development of, 756. 
 
 • falx of, 684. 
 
 - fibres of, formative or diverging, 752. 
 radiating, 754. 
 
 uniting or converging, 752. 
 
 general idea of, 754. 
 
 - fissure, longitudinal, 726. 
 
 Sylvian, 727. 
 
 transverse, great, 727. 
 
 ' ganglia of, 752. 
 hemispheres of, 726. 
 
 • nuclens of, 749 
 
 • internal structure of, 735. 
 
 examined by hardening, 75ff. 
 
 sections of, 736. 
 
 ■— water, 750 
 
 laminae and lamellae of, 717. 
 structure of, 722 (note). 
 
 lobe, sub-peduncular, 718. 
 
 lobes, lateral and median, 717. 
 
 lobule of circumference, 718. 
 
 medulla oblongata, 718. 
 
 pneumogastric nerve, 718. 
 
 lobules or segments, 717. 
 
 medullary centre of, 722. 
 
 peduncles of inferior, 704, 722. 
 
 middle, 710, 722. 
 
 superior, 711, 722. 
 
 sections of, 720. 
 
 — horizontal, 722. 
 
 vertical, 721. 
 
 size and weight of, 716. 
 substances, gray, white, and yellow, 721. 
 surface, upper, 716. 
 lower, 717. 
 
 - tentorium pf, 684. 
 
 ventricle of. See Ventricle, fourth. 
 
 Cerebr jI axteries. See Arteries. 
 — —- nerves. See Nerves, cranial. 
 
 peduncles, substance, &c. See Cerehrvm. 
 
 veins. See Veins. 
 
 Cereiro-spinal axis, 681. 
 
 . • divisions of, 682. 
 
 membranes of, 682. See Arachnoid, 
 
 Dura Mater, and Pia Mater. 
 Cerebrum, 725. 
 
 anfractuosities or sulci, 732. 
 
 of digital cavity, 733. 
 
 inferior surface, 733. 
 
 internal surface, 734. 
 
 superior surface, 734. 
 
 Foville's views of, 755. 
 
 Gall's views of, 751. 
 
 general idea of, 753. 
 
 Mayo's views of, 754 
 
 Rolando's views of, 759. 
 
 ■ lobes of, 731 (note), 735. 
 
 • medullary centres of, 737. 
 
 • peduncles of, 710. 
 
 transverse fibres of, 711. 
 
 course of, in brain, 753. 
 
 ■ structure of, 713. 
 
 ■ section, vertical median, 748. 
 -Willis's, 750. 
 
 • sections of horizontal, 736. 
 
 vertical, transverse, 750. 
 
 general remarks on, 751 
 
 ■ size and weight, 725. 
 
 compared to that of ceio 
 
 bellum, 725. 
 • substance, gray or cortical, 702 (note). 
 
 • white or medullary, 702 (note^ 
 
 ■ surface, inferior, or base, 727. 
 
 ■ superior, or convex, 727. 
 
 unfolding of, by Gall, 753. 
 ventricles of, 753. See Ventricle. 
 Cervical arteries. See Arteries. 
 
 ■ ganglia. See Ganglion. 
 
 ■ nerves. See Nerves. 
 
 ■ plexuses. See Plexuses. 
 vertebrce. See Vertebra and Vertebra 
 
 Cervix uteri, 465. 
 Cheeks, 328. 
 
 development of, 328. 
 
 muscles of, 328. 
 
 structure of, 328. 
 
 vessels of, 328. 
 
 Chemical composition of tissues, &c. See thoM t» 
 
 sues, &c. 
 Chiasma, optic, 728, 819. 
 Chorda tympani nerve, 836. 
 
 - canal for, 672. 
 
 Chorda tendineae, 483. 
 
 vocales, 426. 
 
 inferior or true, 427. 
 
 superior or false, 427. 
 
 Chorion, 631. 
 
 Choroid coat of eye, 657. 
 
 structure of, 657. 
 
 • pigment, 659. 
 
 ■ plexuses, 747. See Plexuses. 
 
 ■ veins of brain, 586. 
 eye, 657. 
 
 Ciliary body, crown, or disc, 656. 
 canal, 656. 
 
 circle, ligament, or ring, 656. 
 
 processes of the choroid coat, 656 
 
 zone of Zinn, 657. 
 
INDEX. 
 
 883 
 
 OfrcteofWilliB, 727. 
 Circular sinus of Ridley, 587. 
 Circumflex arteries. See Artenei, 
 
 veins. See Veins. 
 
 Clavicle, 74. 
 Clitoris, 471. 
 
 artery of, 558. 
 
 crura, glans and prepuce of, 471. 
 
 ligaments and muscles of, 471. 
 
 — nerve of. 807. 
 
 Cochlea, 677. 
 
 aqueduct of, 679. 
 
 axis, columella, or modiolus of, 678. 
 
 lamina gyrorum, or tube of, 678. 
 
 • spiralis of, membranous and osseous, 
 
 678 
 
 nerves of, 681. 
 ■ scalae of, tympanic and vestibular, 677. 
 
 Cochleariform process, 44. 
 Coccygeal vertebrse, 18, 27. 
 Coccyx, 27. 
 Ccecal appendix, 373. 
 Cacum, 371. 
 
 appendix vermiformig of, 373. 
 
 development of, 383. 
 
 • internal surface, 373. 
 
 structure, 378. 
 
 Collateral arteries. See Arteries. 
 
 nerves. See Nerves. 
 
 Colon, 373. 
 
 arch of, 374. 
 
 ascending, 374. 
 
 — — - descending, 374. 
 — — development of, 384. 
 
 ' flexures of, iliac and sigmoid, 371. 
 
 — — internal surface of, 376. 
 
 longitudinal bands of, 374. 
 
 lumbar, left and right, 374. 
 
 structure of, 378. 
 
 transverse, 375. 
 
 Columella of cochlea, 708. 
 
 valve of Vieussens, 712. 
 
 Columnce cameae, 483. 
 
 of rectum, 377. 
 
 Columns, fronto-nasal, 127. 
 
 zygomato-jugal, 127. 
 
 jugal, 127. 
 
 pterygoid, 127. 
 
 • of face, 127. 
 
 of vagina, 469. 
 
 • of spinal cord. See Spinal Cord. 
 
 Comites, arteriae. See Arteries, satellite. 
 
 nervi. See Nerves, satellite. 
 
 venae, 572. 
 
 Commissura mollis, 740. 
 Commissure, anterior, of brain, 741. 
 
 antero-posterior, 753. 
 
 external and internal, of eyelids, 647. 
 
 ■ great transverse, of brain, 735. 
 of lips, 326. 
 
 longitudinal, of brain, or fornix, 737. 
 
 optic, 729. 
 
 ' of pineal body, 742. 
 
 posterior, of brain, 742. 
 
 soft or gray, 741. 
 
 of spinal cord, anterior, 698. 
 
 gray and white, 699. 
 
 at Sylvian fissure, 746. 
 
 Commissures of brain, 742. See Commissure. 
 Common mass of posterior spinal muscles, 201. 
 Communicating arteries. See Arteries. 
 
 nerves. See Nerves. 
 
 Comparison of arm-bone with thigh-bone, 105. 
 
 ■ arteries of upper and lower extremities, 
 
 572. 
 
 bones of upper and lower extremities, 
 
 105. 
 
 carpus and tarsus, 107. 
 
 development of upper and lower extrem- 
 ities, 109. 
 
 enamel and ivory of teeth, 183. 
 
 first rows of carpus and tarsus, 108. 
 
 hand and foot, 107. 
 
 ■ leg with forearm, 105. 
 
 lower parts of radius and tibia, 107. 
 
 metacarpus and metatarsus, 108. 
 
 ■ nerves of upper and lower extremities, 
 
 815. 
 
 permanent and temporary teeth, 187. 
 
 phalanges of fingers and toes, 109. 
 
 Comparison of second rows of caipus and tarsus, 108. 
 
 shoulder with pelvis, 105. 
 
 ■ teeth and bones, 177. 
 
 epidermoid appendages, 177 
 
 upper and lower molar teeth, 181 
 
 upper parts of ulna and tibia, 107, 
 
 Compressor muscles. See Muscles. 
 Conarium, 742. 
 Concha of ear, I 
 
 ■ tragic fossa of, I 
 ■ nose, inferior, 56. 
 
 middle, 41. 
 
 ■ superior, 41. 
 
 Concha, ethmoidal, 41. 
 Condylarthrosis, characters, &c., 114. 
 Condyle, 10. 
 
 humeral, 78. 
 
 Condyles, occipital, 34. 
 
 of lower jaw, 58. 
 
 femur, 95. 
 
 tibia, 97 
 
 Condyloid foramen, anterior, 34. 
 
 — posterior, 34. 
 
 fossa, 34. 
 
 Confluences of the sinuses, 588. 
 Coni vasculosi testis, 452. 
 Conjunctiva, 648. 
 
 Constrictor muscles. See Muscles. 
 Conus arteriosus, 481. 
 Convolutions of brain. See Cerebrum. 
 small intestines, 364. 
 
 Coracoid process, 76. 
 
 Cordiform tendon of diaphragm, 213. 
 
 Cornea, opaque, 655. 
 
 transparent, 655. 
 
 Comicula laryngis, 424. 
 Comu Ammonis, 745. 
 Cornua of hyoid boue, 109. 
 
 lateral ventricle. See Ventrieh 
 
 styloid, 109. 
 
 thyroid cartilage, 424. 
 
 Corona ciliaris, 656. 
 
 radians of Reil, 755. 
 
 of glans penis, 461. 
 
 Coronal bone, 35. 
 
 Coronary arteries. See Arteries. 
 
 ligaments. See Ligaments. 
 
 veins. See Veins. 
 
 Coronoid cavity, 80. 
 
 process of lower jaw, 58. 
 ulna, 80. 
 
 Corpora albicantia, 728. 
 
 structure of, 738. 
 
 Arantii, 486. 
 bigemina, 712. 
 lutea, 462. 
 mammillaria, 728. 
 olivaria, or ovata, 706. 
 quadrigemina, 712. 
 restiformia, 707. 
 Corpus bulbosum, 461. 
 
 artery of, 558. 
 
 nerve of, 806. 
 
 — callosum, artery of, 529. 
 
 ■ — bourrelet or cushion of, 731 
 
 of cerebellum, 711. 
 
 extremity, anterior, 737. 
 
 posterior, 731. 
 
 ■ genu or knee, 737. 
 - peduncles of, 730. 
 
 ■ reflected portion, anterior, 730. 
 
 ■ rostrum or beak, 737. 
 • convolution of, 733. 
 
 ■ ventricle of, 737. 
 
 ■ longitudinal tracts of, 737 
 
 ■ fibres of, 753. 
 
 — cavernosiun penis, 455. 
 
 1 crura of, 455. 
 
 nerves, 456. 
 
 structure, 455. 
 
 ■ vessels, 456. 
 
 ■ dentatum cerebeUi, 721. 
 meduUae, 705. 
 
 fimbriatum, 739. 
 
 — uteri, 464. 
 
 geniculatum externum, 728. 
 internum, 712. 
 
 Highmori, 450. 
 luteum, 462. 
 • mucosuiD of skin, 635- 
 
INDEX. 
 
 Corpus papillare of skin, 689. 
 
 psalloides, 738. 
 
 . reticulare of skin, 635. 
 
 I spongiosum urethrse, 460. 
 
 striatum, 744. 
 
 fibres of, 753. 
 
 lobule of, 731. 
 
 rein of, 745. 
 
 Costal cartilages, 69. 
 Costa, 67. See Ribs. 
 
 of scapula, 76. 
 
 Cotyloid cavity, 88. 
 
 cavities in general, 11. 
 
 Crania, national, 44. 
 
 Cianial nerves, in general. See Nerves. 
 
 in particular. See Nerves. 
 
 — — ganglia. See Ganglia. 
 
 arachnoid. See Arachnoid. 
 
 dura mater. See Dura Mater. 
 
 Cranium, aponeuroses of, 299. 
 
 area of, 45. 
 
 articulations of, 125. 
 
 — base of, exterior of, 45. 
 
 interior of, 46. 
 
 ——— bones of, 34. 
 
 circulation of, arterial, 531. 
 
 — venous, 562. 
 
 - development of, 50. 
 
 - external surface o.'', 45. 
 
 ■ lymphatic system of, 627. 
 
 - in general, 45. 
 
 - internal surface of, 46. 
 
 - mechanism of, 126. 
 
 ■ regions of, 45. 
 
 ■ sutures of, in general, 154. 
 particular. See Sutures. 
 
 -varieties of, 45. 
 - vault of, 45. 
 
 Crest of ilium, 89. 
 
 pubes, 89. 
 
 tibia, 97. 
 
 urethra, 459. 
 
 Crests, occipital, 35. 
 
 Cribriform plate of ethmoid bone, 40. 
 
 Crijtta gaUi, 40. 
 
 ilii, 89. 
 
 vestibuli, 676. 
 
 Crura of clitoris, 471. 
 
 corpus cavemosum, 455. 
 
 diaphragm, 212. 
 
 cerebri, 711. 
 
 Crural arch, 309. 
 
 ring, 310. 
 
 septum, 310. 
 
 Crust of cerebral peduncles, 713 (note). 
 
 Crusta petrosa, 182. 
 
 Crypts of Lieberkuhn, 369. 
 
 Cuneiform bone of carpus, 83. 
 
 Cutaneous nerves. See Nerves. 
 
 Cuticle, 633. 
 
 Cutis, or cutis vera, 631. 
 
 anserina, 630. 
 
 Cystic duct, 397. 
 Cijslis fellea, 396. 
 
 Uo'tns, 446. 
 
 tissue of, 446 (note). 
 
 Deltoid impression, 78. 
 Wfrt/a; arteries. See Arteries. 
 — — canal, inferior, 57. 
 
 canals, superior, 31. 
 
 nerves. See Nerves, 
 
 veins. See Veins. 
 
 Dentata (vertebra), 24. 
 
 Denies. See Teeth. 
 
 Depressor muscles. See Muscles. 
 
 Development of particular bones, organs, or parts 
 
 body. See those bones, organs, &c. 
 Diaphragm, 218. 
 Diarthroses, 114. 
 Digastric fossa, 43. 
 
 groove, 43. 
 
 Digestive apparatus, general view of, 3. 
 D^tal arteries. See Arteries. 
 
 nerves. See Nerves. 
 
 Diploe, 14. 
 
 Diploic canals. 591. 
 
 veins, 585, 591. 
 
 Dissection of different parts. See those parts. 
 Oorsal arteries. See Arteries. 
 
 Dorsal ligaments. See Ligament*. 
 
 nerves. See Nerves. 
 
 veins. See Veins. 
 
 vertebrae. See Vertebra and Ve rt tirtt . 
 
 Dorsum ilii, or external iliac fossa, 88. 
 
 lingua;, 337. 
 
 manus, 82. 
 
 nasi, 64l. 
 
 ——pedis, 99. 
 
 Duct, common biliary, 398. 
 
 ' internal surface, 399. 
 
 structure, 399. 
 
 • cystic, 397. 
 
 structure, 399. 
 
 ' ejaculatory, 452. 
 ' hepatic, 395. 
 
 internal surface, 3W. 
 
 structure, 399. 
 
 — lymphatic, right, 619. 
 
 — nasal, 653. 
 
 — pancreatic, 402. 
 
 — parotid, 341. 
 
 — Stenonian, 341. 
 
 — thoracic, 618. 
 ■ right, 619. 
 
 Warthonian, 342. 
 
 Ducts, biliary, 398. 
 
 lactiferous or galactophorona, 473. 
 
 prostatic, 458. 
 
 of Rivinus, 342. 
 
 Ductus arteriosus, 500. 
 
 communis choledochus, 398. 
 
 ejaculatorius, 452. 
 
 venosus, 600. 
 
 Duodenum, 361. 
 
 curvatures of, 362. 
 
 ~ glands of, 370. 
 — lymphatic glands of, 625. 
 • structure of. See Smalt Intestine. 
 
 Dura mater, 682. 
 
 cranial portion of, 683. 
 cranial nerves of, 686. 
 
 sinuses of, 584. 
 
 structure of, 685. 
 
 uses of, 686. 
 
 vessels of, ( 
 
 dissection of, 682. 
 spinal portiou of, 686. 
 vessels of, 687. 
 
 Ear, auricle of, 666. 
 
 cartilage of, 666. 
 ligaments of, 667. 
 
 muscles of, extrinsic. See MtudUf 
 auricular. 
 
 intrinsic, 668. 
 
 skin of, 668. 
 
 vessels and nerves, 668. 
 
 • drum of. See Tympanum. 
 
 external. See auricle and meatus of. 
 
 general view of, 666. 
 
 internal, or labyrinth of See Labyrinth. 
 
 meatus of external, 668. 
 
 cartilaginous and fibrous portion of, 688. 
 
 — glands of, 669. 
 
 osseous portion of, 44. 
 
 — skin of, 6. 
 
 — internal, 44. 
 . bottom of, 680. 
 
 middle. See Tympanum. 
 
 ossicula of, 673. 
 
 movements of, 674. 
 muscles belonging to, 674. 
 
 tympanum of. See T)/mpanum. 
 
 vessels of, 680. 
 Eighth cranial nerve. See Nerves, glosso-pharyngsal, 
 
 pneumogastric, and spinal accessory. 
 J^aeulatory duct, 452. 
 Elastic tissue, structure of, 174. 
 
 chemical composition of, 174. 
 
 ligaments, general characters of. 112. 
 ■ of vertebrsB, 115. 
 
 Elbow-joint, 143. 
 Eminence, jugular, 34. 
 
 nasal, 35. 
 
 frontal, 35. 
 
 ilio-pectineal, 89. 
 
 hypothenar, 261. 
 
 thenar, 260. 
 
 unciform of lateral ventricle, 730 
 
INOB2. 
 
 88$ 
 
 Eminenlia collateralis, 746. 
 EminentitB natiformes, 712. 
 
 testiformes, 712. 
 
 Enamel of teeth. See Teeth. 
 Enarlhroses, 114. 
 
 Encephalic nerves. See Nerves, craniai. 
 Encephalon, arteries of, in general, 535. 
 
 isthmus of. See Isthmus. 
 
 £mio-cardium, 488. 
 
 lymph, 680. 
 
 Ensiform process, cartilage or appendix, 65. 
 Epactal bones, 50. 
 Epicondyle, 79. 
 Epidermis, 633. 
 Epididymis, 451. 
 
 globus major, 451. 
 
 — minor, 451. 
 
 - structure, 451. 
 
 Epigastric region, 352. 
 Epiglottis, 425. 
 Epiploon, i78. See Omentum. 
 Epithelium ciliated, 323. 
 
 columnar, 323. 
 
 squamous, 323. 
 
 of particular membranes. See those mem- 
 branes. 
 Epitrochlea, 80. 
 
 Erectores muscles. See Mutdt*. 
 Ergot, 736. 
 Ethmoid bone, 40. 
 Ethmoidal bulb, 818. 
 
 cells or sinuses, 40. 
 
 — fossa, 48. 
 
 groove, 40. 
 
 labyrinth, 40. 
 
 EustacJaaa tube, or trumpet, 672. 
 
 cartilaginous and fibrous portion, 672. 
 
 mucous membrane, 673 (note}. 
 
 osseous portion, 44, 672. 
 
 Extensores muscles. See Muscles. 
 Extremities, lower, aponeuroses of, 306. 
 
 articulations of, 153. 
 
 arteries of, 557. 
 
 7 bones of, 87. 
 
 development of, 104. 
 
 lymphatic system of, 619. 
 
 nerves of, 797. 
 
 veins of, 603. 
 
 upper, aponeuroses of, 315. 
 
 arteries of, 531. 
 
 ■ articulations of, 135. 
 
 bones of, 74. 
 
 ——— development of, 87. 
 
 ■ lymphatic system of, 628. 
 
 nerves of, 781. 
 
 •^— ^— veins of, 593. 
 
 upper and lower, arteries of, compared, 572. 
 
 bones of, compared, 105. 
 
 — — ^— — developmont of, compa- 
 red, 109. 
 aeires of, oMnpared, 815. 
 
 Eye, 645. 
 
 appendages of, 646. 
 
 — — brows, 646. 
 
 — — chamber of, anterior, 658. 
 
 ■ posterior, 658. 
 
 globe of, 654. 
 
 humours of, aqueous, 664. 
 
 crystalline, 662. 
 
 ■ vitreous, 66l. 
 
 ■ lashes, 646. 
 ' Uds. 646. 
 
 cartilages of, 647. 
 
 commissures or canthi, 647. 
 
 glands, 648. 
 
 mucous membrane, 647. 
 
 muscles of, 647. 
 
 uses of, 647. 
 
 vessels and nerves, 648. 
 
 ■ membranes of, 654. 
 
 of aqueous humour, 655. 
 
 arachnoid of, 656 (note). 
 
 • capsule of lens, 662. 
 
 choroid coat, 656. 
 
 cornea, 655. 
 
 hyaloid, 661. 
 
 ■ — iris, 657. 
 
 Jacob's, 661. 
 
 pupillary, 659. 
 
 retina, 660. 
 
 Eye, membrane, Raysch's, 659. 
 
 sclerotic coat, 654. 
 
 of vitreous humour, 661. 
 
 muscles of, oblique, 651. 
 
 recti, or straight, 651. 
 
 action of, 651 
 
 nerve of. See Nerve, optic. 
 
 pigment of, 660. 
 
 vessels of, 665. 
 
 Face, area of, 46. 
 
 bones of, 51. 
 
 cavities of, 62. 
 
 circulation of, arterial, 530. 
 
 venous, 593. 
 
 ' development of, general, 63. 
 
 regions of, 63, 64. 
 
 in general, 60. 
 
 lymphatic system of, 626. 
 
 movements of, 238. 
 
 muscles of, 231. 
 
 regions of, 60. 
 
 Facial angle of Camper, 45. 
 
 nerve. See Nerve, portio dura. 
 
 Fallopian aqueduct, 43. 
 
 hiatus, 44. 
 
 ligament, 302. 
 
 tubes, 463. 
 
 fimbriae of, 463. 
 
 structure and uses of, 463. 
 
 Fascia. 
 
 Fall of umbilical vein, 475. 
 
 cerebelli, 684. 
 
 cerebri, 684. 
 See Aponeurosis. 
 
 — cervical, 209. 
 
 — cremasteric, 302. 
 
 — cribriform, 309, 621. 
 
 — dentata, 476. 
 
 — iliac, 302. 
 
 — infundibuliform, of cord, 302. 
 
 — intercolumnar, of inguinal ring, 301. 
 
 — lata, 309. 
 
 iliac portion, 310. 
 
 pubic portion, 311. 
 
 structure, 311. 
 
 obturator, 308. 
 
 propria (sub-peritoneal fascia), 803-30$ 
 
 recto-vesical, 308. 
 
 spermatic, 304, 
 
 superficial, 297, 630. 
 
 tensor muscles of, 294. 
 
 transversalis, 305. 
 
 Fasciculi, muscular, 193. 
 
 of medulla. See MeduUa. 
 
 Fauces, arches of, 330. 
 isthmus of, 330. 
 pillars of, 330. 
 
 Femur, 93. 
 Fenestra ovalis, 670. 
 
 rotunda, and its fossa, 671 
 
 Fibres, muscular, involuntary, 324. 
 voluntary, 193. 
 
 nervous, 767. 
 Fibrous tissue, 298. 
 fV6ro-cartilage of epiglottis, 425. 
 cartilages, 177. 
 
 of particular joints. See those joiata 
 
 FOula, 98. 
 
 Fifth cranial nerve. See Nerve, trifacial 
 Filaments, muscular, 193. 
 nervous, 767. 
 
 FiOet, 712. 
 
 FinU>ri<B of Fallopian tubes, 463. 
 
 Fingers, 86. 
 
 phalanges of, 86. 
 
 — >- and toes, phalanges of, compared, 130. 
 First cranial nerve. See Nerve, olfactory. 
 Fissure, Glasserian, 43. 
 
 glenoidal, 43. 
 
 incisive, 53. 
 
 orbital, 63. 
 
 pterygo-maxillary, 55. 
 
 spheno-maxiUary, 39, 52, 55. 
 
 - sphenoidal, 39. 
 
 Sylvian, 730. 
 
 Fissures of brain, liver, etc. See tbose oigani* 
 
 Flexor muscles. See Muscles. 
 
 Flocculus, 718. 
 
 Fluid, ventricular, 744. 
 
 of Scarpa, 680. 
 
886 
 
 INDEX. 
 
 Fluid, sub-arachnoid, 144. 
 Folds, aryteno-epiglottid, 433. 
 
 glosso-epiglottid, 336. 
 
 pharyngeo-epiglottid, 426. 
 
 Follicles, dental, 184. 
 of Goodsir, 183. 
 
 intestinal. See Intestines. 
 
 Lieberkuhn's, 379. 
 
 sebaceous, 635. 
 
 — solitary, 370. 
 
 of stomach, 360. 
 
 tubular, 360. 
 
 uterine, 471. 
 
 Fontanelles of scull, 49. 
 Foot, bones of, 99. 
 
 compared with hand, 106. 
 
 Foramen, of Bichat, 688. 
 
 ofBotal, 486. 
 
 centrale of retina, 660. 
 
 caecum of frontal bone, 36. 
 
 Morgagni {in tongue), 333. 
 
 ' medulla oblongata, 703- 
 
 condyloid, anterior, 34. 
 posterior, 34. 
 
 infra-orbitary, 59. 
 lacerum superius, 39. 
 
 posterius, 44, 47, 49. 
 
 anterius, 47. 
 
 magnum, 34. 
 mastoid, 43. 
 mental, 57. 
 of Monro, 740. 
 nutritious of humerus, 78. 
 ulna, 79. 
 
 radius, 81. 
 
 femur, 93. 
 
 tibia, 96. 
 
 fibula, 99. 
 
 obturator, 88. 
 occipital, 34. 
 
 optic, 37. 
 
 orbital, internal anterior, 36. 
 posterior, 36. 
 
 ovale of heart, 487. 
 
 ■ sphenoid bone, 38. 
 
 parietal, 42. 
 
 rotundum, 38. 
 
 spheno-palatine, 54. 
 
 spheno-spinosum or spinosun, 38. 
 
 Etylo-mastoid, 43. 
 
 superciliary, 36. 
 
 supra-orbitary, 36. 
 
 vertebral, 20, 21. 
 
 of Winslow, 476. 
 
 Foramina Thebesii, 488. 
 
 malar, 54. 
 
 of bones, 11. 
 
 inter-vertebral, 20, 30. 
 
 posterior, 775 (note). 
 
 sacral, 27. 
 
 Forearm, bones of, 79. 
 
 compared vdth leg, 105. 
 
 Fornix, 739. 
 
 • bulbs of, 740. 
 
 pillars of anterior, 739. 
 
 — posterior, 740. 
 
 Fossa, amygdaloid, 331. 
 
 canine, 51. 
 
 digastric, 43. 
 
 ethmoidal, 48. 
 
 iliac, external, 88. 
 
 internal, 88. 
 
 infra-spinous, 76. 
 
 ischio-rectal, 309. 
 
 jugular, 43. 
 
 lachrymal, 36. 
 
 mental, 58. 
 
 myrtiform, 49. 
 
 navicularis of urethra, 461. 
 
 vulva, 470. 
 
 ear, 670. 
 
 ■ ovalis of heart, 488. 
 
 ■ parietal, 43. 
 
 ■ perineal, 309. 
 
 ■ pituitary, 37, 48. 
 
 • pterygoid, 38. 
 
 ■ scaphoid. See Navicularis. 
 
 ■ spheno-maxillary, 60. 
 
 • sub-lingual, 57, 60. 
 
 ■ sub-maxillary, 57, 60. 
 
 Fossa, ffub-pynmidal, 671. 
 
 sub-scapular, 75. 
 
 supra-sphenoidal, 37. 
 
 supra-spinous, 76. 
 
 temporal, 47. 
 
 zygomatic, 60. 
 Fossa of bones, II. 
 
 - condyloid, 34. 
 
 - frontal, 36. 
 
 - internal iliac, 91. 
 
 - nasal, 63. 
 
 - middle lateral, or spheno-temporal, 48 
 
 - occipital, 35. 
 Fourchette of sternum, 65. 
 
 vulva, 470. 
 
 Fourth cranial nerve. See Nerve, pathette. 
 Fovea hemispherica, 676. 
 - semi-elliptica, 676. 
 Frcenum labii, 324. 
 
 lingus, 336. 
 
 prsputii, 455. 
 
 Frontal bone, 35. 
 
 cells or sinuses, 37. 
 eminence, 35. 
 fosss, 36. 
 
 Fronto-JMgaH suture, 48. 
 
 maxillary suture, 59. 
 nasal suture, 59. 
 — columns, 127. 
 
 parietal suture, 45, 47. 
 
 sphenoidal suture, 48. 
 
 Fundus of stomach, bladder, Ac. See those organ*. 
 Furrow, mylo-hyoidean, 57. 
 
 mento-labial, 326. 
 
 bucco-labial, 326. 
 
 Furrows of heart and spinal cord. See those organa. 
 
 Galactophorous ducts, 473. 
 Galea capitis, 208. 
 Gai2-bladder, 396. 
 
 structure of, 397. 
 
 use of, 400. 
 
 Ganglia, lymphatic. See Lymphatic Glands. 
 Ganglia, nervous, in general. See Nerves, ganglia oj 
 Ganglia, nervous, in particular, 765. 
 
 abdominal, 865. 
 
 of brain, 753. 
 
 cervical, sympathetic. See Ganglion. 
 
 cranial, 765. 
 
 • sympathetic, 854. 
 
 - intercosttj, 765. 
 ■ lumbar, sympathetic, 868. 
 external and intemtl 
 
 branches of, 860. 
 
 - spinal or rachidian, 765. 
 
 - splanchnic, 765. 
 
 - sympathetic, 765. 
 
 — — connexions of, 766. 
 
 structure of, 768. 
 
 -thoracic, 864. 
 
 external branches, 864. 
 
 ' internal branches, 804. 
 
 -vertebral, 761. 
 
 Ganglion of Andersh, 843. 
 
 annulare (of eye), 831. 
 
 cardiac, 862. 
 
 carotid, 856. 
 
 of cerebellum, 722. 
 
 cervical, inferior, 859. 
 
 middle, 859. 
 
 superior, 855. 
 
 ^ — branches of, anterior, 857. 
 
 . external, 858. 
 
 inferior, 858. 
 
 — internal, 858. 
 
 —— superior, 856. 
 
 ■ ciliary, 830. 
 
 — Gasserian, 827. 
 
 — of glosso-pharyngeal, 843. 
 
 — impar, 871. 
 
 — inter-carotid, 858. 
 
 — lenticular, 830. 
 
 — Meckel's, 831. 
 
 — naso-palatine, 831. 
 
 — ophthalmic, and branches, 830. 
 
 — otic, and branches, 837. 
 
 — petrosal, 843. 
 
 — of pneumogastric, 845. 
 
 — of Bibes, 857. 
 
 — of root of hypoglossal, 823 (note). 
 
INDEX. 
 
 887 
 
 (hmglioH of root of spinal accessory, 823. 
 
 semilunar abdominal, 866. 
 
 of fifth nenre, 827. 
 
 solar, 866. 
 
 ' spheno-palatine, and branches, 831. 
 
 sub-maxillary, 837. 
 
 thoracic, first, 859. 
 
 thyroid, 859. 
 
 Gasserian ganglion, 827. 
 
 Genial processes, 58. 
 
 Ginglymus, angular and lateral, 114. 
 
 Glabella, 35. 
 
 *iland, accessory, of parotid, 341. 
 
 epiglottid (so called), 430. 
 
 lachrymal, 652. 
 
 • parotid, 340. See Parotid Gland. 
 
 pineal. See Pineal Gland. 
 
 pituitary, 729. 
 
 prostate, 459. 
 
 • structure, 459. 
 
 sub-lingiial. See Sub-lingual Glana. 
 
 sub-maxillary, 342. See Sub-maxillary Gland. 
 
 thymus, 415. 
 
 • thyroid, 433. 
 
 Glands, agminated, 370. 
 
 arytenoid, 433. 
 
 Brunner's, 370. 
 
 buccal, 329. 
 
 ceruminous, 669. 
 
 conglobate (lymphatic), 614. 
 
 Cowper's, 460. 
 
 duodenal, 370. 
 
 epiglottid, 430. 
 
 of Havers, 113. 
 
 — in knee, 163. 
 
 intestinal. See Intestines. 
 
 labial, 328. 
 
 laryngeal, 432. 
 
 lingual, 337. 
 
 lymphatic, in general, 616. 
 
 particular. 
 
 Glands. 
 
 Groove, superior petrosal, 44. 
 
 of torsion, of humertu, 78. 
 
 Grooves of bones, 12. 
 
 calcaneal, 100. 
 
 carotid, 37. 
 
 cavernous, 37. 
 
 for lateral sinuses, 34. 
 
 on back of radius, 81. 
 
 sacral, 92. 
 
 of spinal cord. See Spinal Cori, 
 
 vertebral, 29. 
 
 Gubemaculum dentis, 189. 
 
 testis, 44«. 
 
 Gula, 344. 
 
 Gulf of the internal jugular, 583, 
 
 Gums, 329. 
 
 HabentB of pineal body, 742. 
 Hamular process of sphenoid bone, 37. 
 cochlea, 678. 
 
 Hand, bones of, 82. 
 
 compared with foot, 107. 
 
 Hairs, description of, general, 638. 
 
 follicles of, 638. 
 
 structure and growth, 638 (note). 
 Harmonia, 114. 
 Harmonic sutures, 114. 
 Haunch bone, 89. 
 Heads of bones, 9. 
 
 particular. See those bonoa. 
 
 See Lymphatic 
 
 mammary, 472. 
 
 Meibomian, 648. 
 
 molar, 329. 
 
 odoriferous, of prepuce, 453. 
 
 oesophageal, 352. 
 
 of Pacchioni, 585, 685. 
 
 palatine, 329. 
 
 Peyer's, 370. 
 
 salivary, 340. See Salivary Glands. 
 
 solitary, 370. 
 
 sudoriferous, 633. 
 
 synovial (so called], 113. 
 
 of trachea, 416. 
 
 tubular, 360, 370. 
 
 Tyson's, 454. 
 
 of uterus, 467. 
 
 of Vesalius (bronchial), 625. 
 
 Glandula socia parotidis, 341. 
 Glans clitoridis, 471. 
 
 penis, 460. 
 
 corona of, 460. 
 
 — - structure of, 461. 
 
 Glasserian fissure, 43. 
 Globuli Arantii, 486. 
 Globus major, 451. 
 
 minor, 451. 
 
 Glomeruli, 437. 
 
 GJoMo-epiglottid folds or ligaments, 430. 
 
 pharyngeal nerve. See Nerve. 
 
 Glenoid cavities in general, 11. 
 
 ligaments. See Ligaments. 
 
 Glottis, 430. 
 
 differences in size of, 435, 
 
 Gomphosis, 114. 
 Groove, basilar, 34. 
 
 bicipital, 78. 
 
 cuboid, 100. 
 
 dental primitive, 184. 
 
 ■ secondary, 184. 
 
 ■ digastric, 43, 47. 
 
 - ethmoidal, 40. 
 
 - inferior petrosal, 49. 
 
 - lachrymo-nasal, 51. 
 
 ■ longitudinal, of cranium, 47 
 
 ■ mylo-hyoidean, 50. 
 • obturator, 88. 
 
 - optic, 37. 
 
 ■ sub-pubic, 88. 
 
 Heart, 479. 
 
 auricles of, external surface, 482. 
 
 interior of, 486. 
 
 muscular fibres of, 490L 
 
 musculi pectinati, 404. 
 
 orifices of, 484. 
 
 ' auriculae of, 482. 
 
 — interior of, 487. 
 
 • bone in, 489. 
 
 ■ cellular tissue, 493. 
 
 ■ chordae tendineee, 483. 
 - columnae cameae, 483. 
 
 ■ conformation of, external, 480. 
 internal, 482. 
 
 ■ development of, 492. 
 
 ■ fibrous framework of, 488. 
 ' foramen of Botal, 486. 
 ovale, 486. 
 
 ' remains of, 486. 
 
 ■ foramina Thebesii, 487. 
 
 - fossa ovalis, 486. 
 
 - function, 492. 
 
 - furrow, auriculo-ventricular, 481. 
 
 inter-auricalar, 482. 
 
 ventricular, anterior and port*- 
 
 nor, 481. 
 . muscular fibres of, 488. 
 structure of, 488. 
 
 ■ nerves of, 492. 
 
 • separation of, into right and left hearts, 490. 
 
 ■ septum, inter-auricular, 482. 
 ventricular, 481. 
 
 • serous coat, external, 487. 
 internal, 487. 
 
 sounds of, 493. 
 
 • structure of, 487. 
 
 ■ tubercle of Lower, 486, 
 
 • valve, Eustachian, 486. 
 
 mitral, 484, 
 
 of Thebesius, 486, 
 
 tricuspid or Iriglochin, 484, 
 
 ■ valves of, auriculo-ventricular left, 484, 
 
 right, 485, 
 
 — ^ semilunar. See Sigmoid. 
 
 ■ sigmoid, aortic, 484. 
 
 pulmonary, 484. 
 
 ventricles of, external surface, 480, 
 
 interior of, 483. 
 
 muscular fibres of, 488. 
 
 . musculi papillares, 484. 
 
 orifices of, 483. 
 
 vessels of, 491. 
 
 zones, fibrous, of, 488. 
 Heel, bone of, 100. 
 Helicotrema, 679. 
 Helix, and its furrow or groove, 666. 
 
 cartilaginous process of, 667. 
 
 Hemorrhoidal arteries. See Arteries. 
 nerves. See Nerves. 
 
 Hepatic artery, in the liver, 394, 395. 
 
888 
 
 INDEX. 
 
 Hepatic duct, 395. 
 
 in the liver, 394, 395. 
 
 Hiatus Fallopii, 44. 
 
 Hilus of spleen, <fcc. See those organs. 
 
 Hip-joint, 1S9. 
 
 ligaments of, 160. 
 
 Horizontal plate of palate bone, 53. 
 
 Human body, general view of, 1-4. 
 
 Humerus, 78. 
 
 Humours of eye. See Eye. 
 
 Hymen, 469. 
 
 Hyoid bone or apparatus, 109. 
 
 ■Hypo- glossal nerve. See Ntne. 
 
 /ieo-coscal valve, 372. 
 
 development of, 384. 
 
 structure of, 373. 
 
 uses of, 373. 
 
 colic valve, 372. 
 
 Ileum, 362. 
 
 structure of. See Intestine, small. 
 
 Iliac arteries. See Arteries. 
 
 flexure, 371. 
 
 fossa, external, 88. 
 
 internal, 88. 
 
 region, 352. 
 
 veins. See Veins. 
 
 /Ko-pectineal eminence, 89. 
 Ilium, 89. 
 
 Impression, deltoid, 78. 
 Incisive canal, 52. 
 
 fissure, 53. 
 
 Incisura tragica, 666. 
 Incus, 674. 
 
 Indented sutures, 115. 
 /n/ra-orbital canal, 51. 
 
 foramen, 59. 
 
 nerves. See Nerves. 
 
 spinous fossa, 76. 
 
 Infundibula of kidneys, 439. 
 Infundibulum of base of brain, 729. 
 
 cochlea, 678. 
 
 nasal fossa, 41, 62. 
 
 right ventricle of heart, 481 
 
 Inguinal canal, 304. 
 
 ring, 303. 
 
 Insula of Reil, 745. 
 
 Iniegumentum, 713 (note). 
 
 /nier-articular cartilages. See Cartilages. 
 
 auricular furrow, 482, 
 
 septum, 482. 
 
 columnar fascia, 301. 
 
 condyloid notch, 95. 
 
 costal arteries. See Arteries. 
 
 nerves. See Nerves, 
 
 spaces, 71. 
 
 lobular fissures, spaces, and vessels of liver, 301 
 
 of lungs, 414. 
 
 osseous arteries. See Arteries, 
 
 cartilages, 112. 
 
 ligaments. See Ligaments. 
 
 muscles. See Muscles. 
 
 • nerves. See Nerves. 
 
 spaces of hand, 84. 
 
 foot, 106. 
 
 • peduncular space, 711, 728. 
 spinous ligaments, 119. 
 
 ■ trochanteric line, 94. 
 
 • ventricular furrow, 480. 
 septum, 480. 
 
 • vertebral foramina, 20, 30. 
 ■ substance or disc, 115. 
 
 ligaments, 115. 
 
 Intestine, laxge, 370. 
 
 . coats of, 378, 379. 
 
 development of, 383. 
 
 divisions of, 371. 
 
 ■ follicles of, 379. 
 
 functions of, 382. 
 
 lymphatic glands and vewek, 379. 
 
 structare of, 378. 
 
 tubuli of, 379. 
 
 vessels and nerves of, 379, 
 
 Intestine, small, 361. 
 
 coats of, 366, 
 
 convolutions of, 364. 
 crypts of, 370. 
 development of, 383. 
 divisions of, 361. 
 follicles of, agmiuated, 369. 
 
 Intestine, small, follicles of, Lieberkuhn'a, 37ft>)i|N^- 
 
 solitary, 369. «^ ' 
 
 functions of, 370, 
 
 glands of, 366. 
 
 ■ lymphatic glands of, 624. 
 
 lymphatics of, 624. 
 
 papillae of, 367. 
 
 • properly so called, 363. 
 
 structure of, 365. 
 
 tubuli of, 370. 
 
 valves of, 366. 
 
 vessels and nerves of, 370. 
 
 villi of, 367. 
 
 Intestines in general, 361. 
 
 development of, 383. 
 
 JnZra-lobular veins of liver, 395 (note). 
 
 spinal veins. See Veins. 
 
 Iris, 657. 
 
 layers of, 659. 
 
 muscular fibres of, 658 (note). 
 
 structure, 658.- 
 
 uses of, 659. 
 
 vessels and nerves of, 659. 
 
 Ischiadic notch, 89. 
 Ischio rectal fossas, 308. 
 Ischium, 89, 
 Island of Reil, 745. 
 Isthmus faucium, 325. 
 
 ovalis (heart), 486. 
 
 of the encephalon, 710. 
 
 comparative anatomy, 715. 
 
 ■ development of, 715. 
 
 divisions of, 710. 
 
 fasciculus of, triangular, 710-711. 
 
 furrow, lateral, of, 710. 
 
 internal structure of, 713. 
 
 lower stratum, 713, 
 
 -- middle stratum, 713. 
 upper stratum, 713. 
 
 sections of, 713, 
 
 Iter dentis, 188, 
 
 Ivory of teeth. See Teeth. 
 
 Jacob's membrane, 660, 
 
 structure of, 661. 
 
 Jaw, lower, 57. 
 
 articulations of, 128, 
 
 upper, bones of, 51, 
 
 — articulations of, 126, 
 
 Jejunum, 362. 
 
 — ; structure of. See Small Intestme. 
 
 Joints. See Articulations. 
 Jugal columns, 127. 
 
 bone, 54. 
 
 Jugular eminence, 34. 
 
 fossa, 43. 
 
 veins. See Veins. 
 
 internal, sinus of, 583. 
 
 Kidneys, 436, 
 
 - acini, 438, 
 -- adipose capsule of, 437 
 
 - calyces of, 439, 
 
 - coat of, 437. 
 
 - cortical substance of, 438. 
 
 - development of, 440. 
 
 - functions of, 440. 
 
 - glomeruli, 437. 
 
 - hilus or fissure, 436. 
 
 - papillae, 437. 
 ■- pelvis of, 440. 
 
 - pyramids of, Ferreim'a, 437, 
 Malpighi's, 437. 
 
 ■ tubes of, convoluted, 437, 
 ' straight, 437. 
 
 tubular portion, 438. 
 
 — structure of, 438, 
 
 • vessels and nerves, 438, 
 
 See thoM 
 
 Knee-joint, arteries, ligaments, and nerves, 
 parts. 
 
 Labia pudendi, 470. 
 Labyrinth, ethmoidal, 40, 
 
 fluids of, 679. 
 
 lining membrane of, 680. 
 
 membranous, 679. 
 
 osseous, 675. See Cochlea, Semi-ciraikm 
 
 Canals, and Vestibule. 
 
 Lacerated, foramen anterior, 47. 
 
 posterior, 44. 
 
IKDEX. 
 
 Lacerated, foramen superior, 39. 
 Lacerti teretes of heart, 483. 
 Lachrifmal bone, 56. 
 
 canals, 651. 
 
 caruncula, 647. 
 
 gland, 651. 
 
 groove, or fossa, 36, 651. 
 
 papills, or tubercles, 645. 
 
 passages, 651. 
 
 mucous coat of, 654. 
 
 ■ puncta, 652. 
 sac, 653. 
 
 Lachrymo-aasal groove, 51. 
 
 canal, 652. 
 
 Lacteals, 611. 
 
 of intestines, 612. 
 
 Lactiferous ducts, 473. 
 Lacuna magna, 460 (note). 
 Lacuna of urethra, 460. 
 Lacus lachrymalis, 647. 
 Lambdoidal suture, 46. 
 Lamina cinerea, 730. 
 
 of cornea, 745. 
 
 cribrosa of ethmoid, 40. 
 
 of internal auditory meatus, 678, 680. 
 
 gyrorum, 677. 
 
 papyracea, 41. 
 
 spiralis, membranous and osseous, 677. 
 
 Laryngeal nerves. See Nerves. 
 Larynx, 422. 
 
 articulations of, 426. 
 
 cartilages of, 423. 
 
 ossification of, 435. 
 
 Ligaments of auricle, intrinsic, 667. 
 
 of bladder, anterior, 308, 440. 
 
 ■ posterior, 440, 475. 
 
 broad, of liver, 386. 
 
 uterus, 465. 
 
 ' calcaneo-cuboid, inferior, 173. 
 internal, 173. 
 superior. 172. 
 
 • scaphoid, inferior, 172. 
 superior, 172. 
 
 of canthus, external, 647. 
 capsular, acromin-clavicular, 135. 
 
 atlanto-axoid, 119. 
 
 carpo- metacarpal of thumb, 150. 
 
 ■of little finger, ISO. 
 
 hip-joint, 160. 
 knee-joint, 166. 
 occipito-atlautoid, 118. 
 axoid, 119. 
 
 - development of, 435 
 
 • functions of, 435. 
 
 • glottis, 430. 
 
 • m general, 429. 
 
 • ligaments of, 425. 
 
 • mucous membrane and glands of, 475. 
 
 • muscles of, 427. 
 ' sinus of, 434. 
 
 ' surface, external, 429. 
 internal, 430. 
 
 ■ ventricle of, 427. 
 
 ' vessels and nerves, 435. 
 
 Leg, articulations of, 168. 
 
 bones of, 96. 
 
 compared with forearm, 105. 
 
 fascia of, 311. 
 
 Lemniscus, 711. 
 
 Lens. See Crystalline Lens. 
 Levator muscles. See Muscles. 
 Levers, three orders of, in body, 199. 
 Ligamenta-lsXs. of uterus, 475. 
 
 subflava, general characters, 112. 
 
 of vertebral column, 115. 
 
 Ligaments in general, 1 13. 
 
 articular, 112. 
 
 capsular, 1 12. 
 
 interosseous, 112. 
 
 membranous, 112. 
 
 structure of, 174. 
 
 yellow or elastic, 112. 
 
 Idgaments in particular, 113. 
 
 accessory, of shoulder-joint, 139. 
 
 hip-joint, 160. 
 
 knee-joint, 165. 
 
 • Weitbrecht, 144. 
 
 ' alar, of axis (or odontoid), 119. 
 
 of knee, 165. 
 
 ' of ankle-joint, lateral, anterior external, 1 69. 
 
 external proper, 169. 
 
 internal, 169. 
 
 posterior, 169. 
 
 annular, of radius, 142, 
 
 atlas, 117. 
 
 carpus, anterior, 318, 
 
 dorsal, 318. 
 
 tarsus, dorsal and lateral, 313. 
 
 arjrteno-epiglottid, 426. 
 astragalo-calcaneal, interosseous, 171. 
 • external, 171. 
 
 posterior, 171. 
 
 scaphoid, superior, 172. 
 
 atlanto-axoid, anterior, 117. 
 ■ posterior, 117. 
 capsular, 117. 
 
 odontoid, transverse or annular, 117, 
 crucial, 117. 
 
 scapulo-humeral, 137. 
 
 sterno-clavicular, 136. 
 
 ■ of each row of carpal bones, 147. 
 
 - two rows of carpal bones, 147. 
 carpo-metacarpal, dorsal, 150. 
 
 palmar, 150. 
 
 interosseous, with os mag 
 
 num, 150. 
 of little finger, 150. 
 
 thumb, 150. 
 
 cervical, posterior, of quadrupeds, 117. 
 check, of axis (or odontoid), 119. 
 chondro-sterual, anterior, 131. 
 
 interosseous, 131. 
 
 posterior, 131. 
 
 ■ superior and inferior, 131 
 
 ' xiphoid, 131. 
 
 ciliary, 656. 
 
 conoid, 135. 
 
 coraco-acromial. 140. 
 
 clavicular, anterior, or trape7oid, 136 
 
 posterior, or conoid. 136 
 
 coraco-humeral, 139. 
 
 — coracoid, 139. 
 
 — costo-clavicular, 138. 
 coracoid, 1 39. 
 
 ■ transverse, interosseous, 131 
 posterior, 131. 
 
 — superior, 131. 
 
 ■vertebral, anterior, 131. 
 
 inferior, 131. 
 
 interosseous, 131. 
 
 stellate, 131. 
 
 superior, 131. 
 
 cotyloid, of hip-joint, 159. 
 
 crico-arytenoid, 426. 
 
 thyroid, middle and lateral, 436 
 
 crucial, of atlas, 117. 
 
 knee-joint, 164. 
 
 of cuneiform bones of tarsus, 170. 
 
 and scaphoid, 171 
 
 third and cuboid, l7l 
 
 deltoid, 169. 
 
 dorsal, annular, of carpus, 318. 
 ■ tarsus, 313. 
 
 carpo-metacarpal, 149. 
 
 • of carpus, 149. 
 
 — metacarpus, 149. 
 
 — metatarsus, 175. 
 
 ■ tarso-metatarsal, 175. 
 
 • of tarsus, 171. 
 
 elbow-joint, external lateral, 141. 
 
 internal lateral, 141. 
 
 anterior, 141. 
 
 ■ posterior, 142. 
 
 falciform, 303 
 Fallopius's, 302 
 of Ferr^in, 427. 
 Gimbernat's, 303. 
 glenoid, carpal anterior, 148. 
 ■ posterior, 148 
 
 metacarpo-phalangal, 152. 
 metatarso-phalangal, 175. 
 phalangal, of fingers, 153. 
 toes, 176. 
 
 scapulo-humeral, 138. 
 
 of auricle, anterior and posterior, 667. 
 
 5U 
 
 glosso-epiglottid, 425. 
 
 of hip-joint, anterior superior, 160. 
 
 — accessory. 160. 
 
 cotyloid, 160. 
 
 iuter-articular, 161. 
 
890 
 
 
 Ligaments of hip-joint, round, 161. 
 
 capsular, 160. 
 
 — I of humero-cubital, 141. 
 
 hyo-epiglottid, 425. 
 
 ilio-lurabar, 156. 
 
 inter-articular, acroinio-claTicular, 135. 
 
 of hip-joint, 160. 
 
 of shoulder-joint, 137. 
 
 sterno-clavicular, 136. 
 
 temporo-maxillary, 128. 
 
 of wrist, 143. 
 
 osseous, astragalo-calcaneal, 171. 
 
 of carpal bones, 147. 
 
 carpo-metacarpal, 149. 
 
 costo- transverse, 131. 
 
 vertebral, 131. 
 
 of forearm, 144. 
 
 — knee-joint, 164. 
 
 — leg, 169. 
 
 — OS magnum and metacar- 
 
 pus, 149. 
 
 ■ metacarpal, 149. 
 
 ■ metatarsal, 175. 
 peroneo-tibial, 168. 
 pubic, 156. 
 radio-cubital, 143. 
 sacro-iliac, 155. 
 tarsal, of first row, 171. 
 
 ■ second row, 171. 
 
 tarso-metatarsal, 175. 
 
 vertebral, 115. 
 
 clavicular, 137. 
 
 spinous, 116. 
 
 vertebral, 115. 
 
 of knee-joint, 163. 
 
 accessory, 166. 
 
 adipose (so called), 166. 
 
 alar, 166. 
 
 anterior, 163. 
 
 capsular, 163. 
 
 crucial anterior, 164. 
 
 • posterior, 163. 
 
 ■ inter-articular, 163. 
 
 osseous, 164. 
 
 lateral, external, 163. 
 internal, 163. 
 
 ■ mucous (so called), 166. 
 • posterior, 163. 
 transverse, 163. 
 
 of laryni, 425. 
 — malleus, 673. 
 
 metacarpo-phalangal, glenoid, 152. 
 
 lateral, 152. 
 
 ■of thumb, 152. 
 
 of metacarpus, 148. 
 metatarso-phalangal, glenoid, 176. 
 — lateral, 176. 
 
 of metatarsus, 175. 
 
 occipito-atlantal anterior, superficial, 116. 
 
 deep, 116. 
 
 capsular, 117. 
 
 lateral, 117. 
 
 posterior, 116. 
 
 ' axoid, lateral, 120. 
 middle, 120. 
 
 odontoid, lateral, 120. 
 middle, 120. 
 
 orbicular, of acromio-clavicular articula- 
 tion, 137. 
 
 ■ of hip-joint, 158. 
 
 scapulo-humeral, 139. 
 
 sterno-clavicular, 137. 
 
 palmar of carpo-metacarpal joints, 149. 
 
 carpus, 147. 
 
 - metacarpus, 148. 
 
 of patella, 164. 
 
 perineal, 307. 
 
 peroneo-tarsal, anterior external, 170. 
 
 external, 170. 
 
 posterior, 170. 
 
 — of peroneo-tibial articulations, 167, 168. 
 
 — perpendicular, 170. 
 
 — phalangal of fingers, glenoid, 153. 
 ■ lateral, 153. 
 
 toes, glenoid, 177. 
 lateral, 177. 
 
 of pisiform and cuneiform bones, 147. 
 
 plantar inferior, 174. 
 
 of metatarsus, 176. 
 
 tarso-metatarsal, 176. 
 
 Ligaments, plantar of tarsus, 172 
 
 Poupart's, 302. 
 
 proper, of scapula, anterior, 140. 
 
 posterior, 140. 
 
 - pterygo-maxillary, 235. 
 
 - pubic anterior, 155. 
 
 inferior, 155. 
 
 interosseous, 155. 
 
 posterior, 155. 
 
 superior, 155. 
 
 triangular, 155. 
 
 ■ radiated chondro-sternal, 133. 
 
 ■ of radio-carpal articulation, 145. 
 cubital articulations, 144. 
 
 ■ recto-uterine, 467. 
 
 ■ round, of forearm, 144. 
 hip-joint, 161. 
 
 ■ uterus, 466. 
 
 ■ sacro-coccygeal, anterior, 120. 
 posterior, 120. 
 
 ■ iliac, anterior, 154. 
 
 interosseous, 154. 
 
 posterior vertical, 155. 
 
 superior, 154. 
 
 sciatic, great, 155. 
 
 small, 155. 
 
 vertebral, 120. 
 
 — scaphoid and cuboid, 172. 
 
 — of shoulder-joint, 136. 
 
 — spheno-maxillary, 129. 
 
 — stellate, costo-vertebral, 130. 
 ' or radiated, chondro-stemal, 13L 
 
 • stylo-maxillary, 129. 
 mylo-hyoid, 129. 
 
 ■ sub-pubic, or inferior pubic, 156. 
 
 • supra-spinous, 119. 
 
 ■ suspensory of clitoris, 471. 
 ' penis, 456. 
 
 — liver, 386, 475. 
 
 — of first row of tarsal bones, 171 . 
 second row of tarsal bones, 171. 
 
 — tarso-metatarsal, dorsal, 174. 
 
 interosseous, 174. 
 
 oblique of fifth toe, 175. 
 
 plantar, 174. 
 
 — of temporo-maxillary articulation, lateral 
 
 external, 128. 
 
 — internal, 129. 
 
 — thyro-arytenoid, or chords vocales, 427. 
 epig:lottid, 425. 
 
 hyoid, middle and lateral, 425. 
 
 — tibio-tarsal, anterior, 169. 
 internal, 169. 
 
 posterior, 169. 
 
 ■ of tragus, 667. 
 
 • transverse of atlas, 117. 
 
 knee, 163. 
 
 metacarpus, 149. 
 
 • trapezoid, 136. 
 
 ■ triangular of perinaeum, 307. 
 
 penis, 455. 
 
 symphysis pubis, 156. 
 
 urethra, 307. 
 
 wrist, 143. 
 
 ■ of two rows of tarsal bones, 171. 
 
 ■ vertebral, anterior common, 116. 
 interosseous, 116. 
 
 • posterior, 116. 
 
 — yellow elastic, 117. 
 
 - vesico-uterine, 467. 
 
 - of Weitbrecht, 144. 
 
 — Winslow, 164. 
 
 — wrist-joint, external anterior, 146. 
 
 — internal anterior, 146. 
 
 middle anterior, 146. 
 
 ■ external lateral, 146. 
 
 . internal lateral, 146. 
 
 posterior, 146. 
 
 of Zinn, 650. 
 
 Ligamentum arcuatum of diaphragm, 213 
 
 denticulatum, 694. 
 
 fibulae anterius, 170. 
 
 medium, 170. 
 
 perpendiculare, 170. 
 
 posterius, 170. 
 
 gastro-phrenicum, 354. 
 
 latum pulmonis, 413. 
 
 longum plantae, 173. 
 
 mucosum of knee-joint, 164. 
 
 nnchffi, 202. 
 
INDEX. 
 
 891 
 
 Ligamentum-piteXIs, 164. 
 
 phrenico-lienale, 403. 
 
 proprium anterius scapuls, 140. 
 
 posterius scapula, 140. 
 
 teres of forearm, 144. 
 
 ■ '■ hip-joint, 161. 
 
 lambs. See Extremities. 
 
 Limbus luteus, 660. 
 
 Line, inter-trochanteric, 94. 
 
 mylo-hyoidean, 57. 
 
 naso-labial, 327. 
 
 Lines, semicircular of occipital bone, S3> 
 
 -— ^— — ^— OS cuxse, 88. 
 
 Litua alba, 301. 
 
 cervical, 300. 
 
 aspera, 94. 
 
 Ups, 325. 
 
 — — development of, 326. 
 
 movemeuts of, 238 
 
 muscles of, 326. 
 
 structure of, 326. 
 
 uses of, 327. 
 
 vessels of, 327. 
 
 Liquor Cotunni, 680. 
 
 • Morgagni, 663. 
 
 of Scarpa, 680. 
 
 Liver, 385. 
 
 acini of, 390. 
 
 circumference of, 389. 
 
 • coats of, 390. 
 
 colour and fragility, 389. 
 
 development of, 399. 
 
 ducts of, 391 (notes). 
 
 excretory apparatus of, 395. 
 
 figure, 386. 
 
 fissures, 387. 
 
 functions, 400. 
 
 groove for vena cava, 389 
 
 hilusof, 388. 
 
 ligament, broad or suspensory, 386. 
 
 coronary, 390. 
 
 falciform, 386. 
 
 triangular, left and right, 390 
 
 lobes, 387. 
 
 lobules or granules, 388. 
 
 arrangement of, 391. 
 
 ' structure of, 394 (note). 
 
 - lymphatics of, 393. 
 -nerves of, 393. 
 -porta of, 388. 
 
 - proper tissue, 390 (note). 
 
 ■ situation, 385. 
 
 ■ size, 385. 
 -structure of, 390. 
 
 - surface, inferior or plane, 386. 
 • superior, 386. 
 
 Lungs, vessels and nerves of, 421. 
 
 weight of, absolute and specific, 410. 
 
 Lymphatic duct, right, 619. 
 
 - glands in general, 616. 
 
 preparation of, 617. 
 
 structure of, 617. 
 
 in particular, 619. 
 
 axillary, 628. 
 
 bronchial, 625. 
 
 cervical, deep, 628. 
 
 superficial, 627. 
 
 ■ of cranium, 626. 
 
 • duodenal, 624. 
 
 ■ of face, 626. 
 
 ■ ileo-colic, 624. 
 
 • iliac, external, 622. 
 
 internal, 622. 
 
 ■inguinal, 619. 
 
 ■ intercostal, 625. 
 
 ■ of intestine, great, 624. 
 — small, 624. 
 
 of liver, 623. 
 
 of lower extremity, 620. 
 
 lumbar, 621. 
 
 mammary, 625. 
 
 mediastinal, 625. 
 
 mesenteric, 625. 
 
 meso-colic, 624. 
 
 of pancreas, 624. 
 
 parotid, 627. 
 
 of pelvis, 621. 
 
 popliteal, 619. 
 
 pulmonary, 625. 
 
 sacral, 621. 
 
 of spleen, 624. 
 
 of stomach, 624. 
 
 .sub-maxillary, 627. 
 
 sub-sternal, 625. 
 
 tibial anterior, 619. 
 
 tracheal, 627. 
 
 of upper extremity, 628. 
 
 ■ part of trunk, 628. 
 
 ■ hearts of lovfcr animals, 617. 
 
 ' networks, superficial and deep, 613. 
 
 ■ plexuses, 612. 
 system, 611. 
 
 vessels of, 392. 
 
 arrangement of, 393. 
 
 Lobes and lobules of organs. See thorn organs. 
 Lobule of ear, 666. 
 Lobulus caudatus, 389. 
 
 quadratus, 389. 
 
 SpigeUi, 389. 
 
 Locus niger, 751. 
 
 perforatus anterior, 731. 
 
 middle or posterior, 727. 
 
 Longissimus dorsi. See Muscles. 
 
 Longitudinal fissures of liver, &c. See those organs. 
 
 vein of spine. See Vein*. 
 
 Luette of bladder, 459. 
 Lumbar nerves. See Nerves. 
 
 region of abdomen, 352. 
 
 veins. See Veins. 
 
 vertebne. See Vertebra and Vertebra. 
 
 Lungs, 409. 
 
 air-ceUs of, 415. 
 
 air-tubos of, 416. 
 
 cellular tissue of, inter-lobular, 415. 
 
 development of, 421. 
 
 external conformation of, 411. 
 
 ^, fissures of, inter-lobular, 411. 
 
 foetal, 421. 
 
 functions, 422. 
 
 lobes of, 411. 
 
 lobules of, 415. 
 
 structure of, 419. 
 
 lymphatic system of, 421. 
 
 root of, 412. 
 
 size of, 409. 
 
 ■ structure of, 413. 
 
 vessels in general, 611. 
 
 aflferent, 614. 
 
 ' anastomoses of, 614. 
 
 branches of, 614. 
 
 coat of external, 616. 
 
 ' internal, 616. 
 
 course and direction, 614. 
 ' deep and superficial sets of, 618. 
 ■ efferent, 614. 
 
 origin of, in different tissues, 612. 
 • preparation of, 617. 
 
 structure of, 616. 
 
 terminations of, 614. 
 
 valves of, 617. 
 
 vessels of, 616. 
 
 in particular, 618. 
 
 of bones, 16. 
 
 of brain, 628. 
 
 of cellular tissue, 613. 
 
 cervical, 628. 
 
 ' posterior, 639. 
 
 of cranium, 637. 
 
 dorsal, 629. 
 
 of dura mater, 627. 
 
 epigastric, 622. 
 
 of external genitals, male and &• 
 
 male, 620. 
 of face, 627. 
 gluteal, 620. 
 of heart, 626. 
 ilio-lumbar, 622. 
 intercostal, 626. 
 of intestines, great, 625. 
 ■ small, 625. 
 
 of kidneys, 622. 
 
 of lining membrane of bloodvessels, 
 
 613. 
 of liver, deep, 623. 
 
 superficial, 623. 
 
 ' of lower extremity, deep and super* 
 ficial, 619. 
 lumbar, lateral, 622. 
 
 ■ superficial, 620. 
 
 of lungs, deep and superficial, 626. 
 
892 
 
 INSEJX. 
 
 Lymphatic vessels, mammary, internal, 626. 
 
 meningeal, 627. 
 
 of mucous membranes, 612. 
 
 occipital, 627. 
 
 of pelvis, 621. 
 
 pericardiac, 626. 
 
 periuaeal, 620. 
 
 peroneal, 620. 
 
 of serous and sysovial tissues, 613, 
 
 of skin, 613. 
 
 of spleen, 624. 
 
 of stomach, 624. 
 
 sub-sternal, 626 
 
 supra-renal, 622, 
 
 temporal, 626. 
 
 of testicles, 622. 
 
 thorax, 625. 
 
 thymic, 626. 
 
 thyroid, 627. 
 
 tibial, anterior and posterior, 620. 
 
 of upper extremity, 628. 
 
 • part of trunk, 628. 
 
 uterine 628. 
 
 Lyra, 738. 
 
 Macula cribrosa, 676l 
 Malar foramina, 54. 
 
 process, 51. 
 
 bone, 54. 
 
 Malleolus, external, 97. 
 
 internal, 98. 
 
 Malleus, and ligament of, 673. 
 
 muscles of, 673. 
 
 Mamma, 471. 
 
 adipose tissue of, 473. 
 
 development of, 474. 
 
 fibrous tissue of, 473. 
 
 glandular tissue of, 473. 
 
 lactiferous ducts of, 473. 
 
 ■ of the male, 473. 
 
 vessels and nerves of, 474. 
 
 Mammary gland. See Mamma. 
 Mammillm. See Nipples. 
 Mammillary enlargements of posterior median colunms 
 of spinal cord, 704. 
 
 of inferior vermis, 716, 718. 
 
 tubercles, 426. 
 
 Manubrium of malleus, 673. 
 
 of sternum, 65. 
 
 Marrow of bones, 12. 
 
 Massa camea Jacobi Sylvij, 291. 
 
 Mastoid foramen, 43. 
 
 portion of temporal bone, 43. 
 
 process, 43. 
 
 Maxillary arteries. See Arteries. 
 
 bone, inferior, 57. 
 
 superior, 51. 
 
 canal, superior, 51. 
 
 inferior, 58. 
 
 nerves. See Nervet. 
 
 tuberosity, 51. 
 
 Jlfar^o-dentatus, 660. 
 MeeUus of nose, inferior, 54. 
 
 middle, 41. 
 
 • superior, 41. 
 
 auditorius externus, 44. 
 
 iutemus, 44. 
 
 urinarius, female, 471. 
 
 male, 461. 
 
 See Bar. 
 See Ear. 
 
 Mechanism of particular joints. 
 Mediastinum, anterior, 414. 
 posterior, 413. 
 
 See those joints. 
 
 Medulla oblongata, 702. 
 
 comparative anatomy of, 709. 
 
 development of, 708. 
 
 external conformation of, 702. 
 
 anterior surface, 703. 
 
 lateral surfaces, 704. 
 
 — posterior surface, 704. 
 
 ' faisccaux innomines of, 706. 
 
 at base of brain, 706. 
 
 • in isthmus, 715. 
 
 fasciculi graciles, 708 (note). 
 
 olivary, 708 (note). 
 
 re-enforcing, 708. 
 
 teretes, 708 (note). 
 
 • pyramidal, 702, 704, ' 
 
 fibres of, antero-posterior, 707. 
 
 arched, 704. 
 
 decussation of, 706. 
 
 MeduUa oblongata, foramen caecum of, 703. 
 
 furrow of median, anterior, 703. 
 
 posterior, 704. 
 
 ■ internal structure of, 706. 
 
 — neck of, 702. 
 
 sections of, 705. 
 
 of long bones, 12. 
 
 spinalis. See Spinal Cord. 
 
 examined by hardening, 706. 
 
 sections, 705. 
 
 water, 706. 
 
 Medullary canal of long bones, 13. 
 membrane, 14. 
 
 Meibomian glands, 648. 
 Membrana nictitans, 648. 
 
 pupillaris, 659. 
 
 Ruyschiana, 657. 
 
 sacciformis, 143. 
 
 tympani, 669. 
 
 secundaria, 670. 
 
 uvea, 659. 
 
 Membrane, hyaloid, 661. 
 
 obturator, or sub-pubic, 155. 
 
 Membranes of cerebro-spinal axis. See ATodmotd, 
 Dura Mater, and Pia Mater. 
 
 of eye. See Eye. 
 
 fibro-mucous See Tibro-mucous Mem- 
 
 branes. 
 
 — fibro-serous. See Fibro-serous Membranes 
 
 — — — ^ mucous. See Mucous Membranes. 
 — ^^^— serous. See Serous Membranes. 
 ^— — ^— synovial. See Synovial Membranes. 
 Membranous labyrinth, 679, 
 
 part of urethra, 458. 
 
 Meningeal arteries. See Arteries. 
 Meninges, 681. 
 Meningoses, 113. 
 Meniscus, 113. 
 Mental fossa, 57. 
 
 foramen, 57. 
 
 process, 56. 
 
 Mesentery, 364, 477. 
 
 left layer, 475. 
 
 right layer, 475. 
 
 Meso-cxcxim, 471. 
 ■ colon, iliac, 475. 
 
 left and right, 475. 
 
 transverse, 375. 
 
 layer, inferior, 476. 
 
 — superior, 477 
 
 ' ■ - ga-strium, 478. 
 — — rectum, 475. 
 Metacarpus, bones of, 84. 
 
 ■ differential characters, 89. 
 
 general characters, 85. 
 
 ■ compared with metatarsus, 109. 
 
 Metatarsus, bones of, 103. 
 
 characters, general, 103. 
 
 differential, 102. 
 
 compared with metacarpus, 109. 
 
 Milk teeth. See Teeth. 
 
 Modiolus of cochlea, 678. 
 
 Mom Veneris, 470. 
 
 Morsus diaboli, and fimbriie of Fallopian tube, 463. 
 
 Motores oculi nerves. See Nerves. 
 
 Mouth, component parts of, 422. 
 
 situation, dimensions, &c., 422. 
 Movements of joints. See Articulations. 
 in general, 148. 
 
 lips and face, 238. 
 
 Mucous bursae (so called), 175. 
 
 membranes, in general, 421. 
 
 chemical composition, 42L 
 
 epithelium, 421. 
 
 ■ of particular organs. See thoa 
 
 organs. 
 — structure, 421. 
 
 Mucro, 65. 
 MultifiduM spinae. See Muscles- 
 Muscles in general, 190. 
 
 action of, 194. 
 
 angle of incidence on bones, 195. 
 
 antagonist, 196. 
 
 aponeuroses of, 193. 
 
 arrangement, physiological, of, 291. 
 
 attachments of, 192. 
 
 — fixed, 191 
 
 movable, 193. 
 
 broad, 190. 
 conge.nen<ns. 197. 
 
IKDEX. 
 
 Miuehs, direction of, 191. 
 
 ' figure of, 191. 
 
 insertion of, into other puts, 19t. 
 
 long, 191. 
 
 momeutum of, 195. 
 
 nerves of, 763. 
 
 nomenclature of, 190. 
 
 number of, 190. 
 
 orde' of description of, 197. 
 
 origin and termination of, 198. 
 
 preparation of, 197. 
 
 relations of, to other ports, 101 
 
 satellite, 192. 
 
 sheaths for, 296. 
 
 short, 191. 
 
 structure of, 193. 
 
 tendons of, 193. 
 
 uses of, 194. 
 
 volume of, 190. 
 
 in particular, 196-291. 
 
 ——^— of particular organs, parts, or regions, 
 those organs, parts, or regions. 
 ' abductor brevis pollicis, 260. 
 
 digiti minimi, 262. 
 
 pedis, 289. 
 
 See 
 
 ' indicia, 264. 
 
 ' longus pollicis, 258. 
 
 • oculi, 650. 
 
 ■ pollicis, 287. 
 
 — pedis, 277. 
 
 • accelerator urinse, 456. 
 ' accessorious pedis, 280. 
 
 ad sacro-lumbalem, 877. 
 
 • adductor brevis femoris, 276. 
 
 digiti minimi (opponens), 281. 
 
 longus femoris, 276. 
 
 magnus femoris, 276. 
 
 oculi, 650. 
 
 pollicis manOs, 288. 
 
 pedis, 288. 
 
 anconeus, 258. 
 
 anterior auriculs, 230. 
 
 antitragieus, 667. 
 
 articulo-spinalis, 201. 
 
 arytenoideus, 429. 
 
 obliquus, 429. 
 
 transversus, 430. 
 
 • aryteno-epiglottideus, 430. 
 ' attoUens auriculam. 231. 
 • oculum, 650. 
 
 — attrahens auriculam, 231. 
 
 — auricularis anterior, 231. 
 posterior, 231. 
 
 -- superior, 231. 
 
 • azygos uvulie, 332. 
 ' basio-glossus, 338. 
 
 biceps cruris vel femoris, ! 
 
 flexor cubiti, 245. 
 
 — biventer cervicis, 201. 
 
 — brachialis anticus, 246. 
 
 — buccinator, 235. 
 
 — bulbo-cavernosus, 456. 
 
 — caninus, 236. 
 
 — cerato-glossus, 338. 
 
 — chondro-glossus, 338. 
 
 — ciliaris, 232. 
 
 — circumflexus palati, 332. 
 
 — coccygeus, 381. 
 
 — complexus, 205. 
 minor, 205. 
 
 — compressor narium, 233. 
 nrethrffi, 460. 
 
 in the female, 470. 
 
 — vente dorsalis penis, 460. 
 
 - constrictor inferior, 346. 
 
 iiiedius, 347. 
 
 superior, 347. 
 
 — vagince, 469. 
 
 — coraco-brachialis, 246. 
 
 — coTrngator supercilii, 232. 
 
 — cremaster, 210,450. 
 
 — crico-arytenoideus lateralis, 428. 
 
 posticus, 428. 
 
 CBsophageus, 352. 
 
 thyroideus, 421. 
 
 — crotaphyte, S40. 
 
 — crureus, 273. 
 
 — cutanei, 294. 
 
 — deltoideus, 241. 
 
 — depresssor alae nasi, 334. 
 
 Muscles, depressor angali oris, 837. 
 
 labii inferioris, 237. 
 
 superioris alsque nasi, 234. 
 
 oculi, 650. 
 urethrjE (Santorini), 460. 
 in the female, 470. 
 
 diaphragma, 218. 
 
 digastricus, 228. 
 
 elevatores nrethno (Santorini), 400. 
 
 erector clitoridis, 471. 
 
 penis, 456. 
 
 spinee, 202. 
 
 extensor brevis digitorum pedis, 286. 
 
 pollicis, 259. 
 
 carpi radialis brevior, 255. 
 
 longior, 355. 
 
 ' ulnaris, 258. 
 
 — communis digitorum, 866. 
 
 — digiti minimi, 257. 
 
 — indicis, 259. 
 
 — longus digitorum pedis, 278. 
 pollicis, 259. 
 
 — ossis metncarpi pollicis, 258. 
 
 — primi internodii pollicis, 258. 
 
 — proprius auricularis, 256. 
 indicis, 259. 
 
 — pollicis pedis, 279. 
 
 secundi internodii pollicis, 958. 
 
 flexor accessorius, 290. 
 
 brevis digiti minimi, 262. 
 
 minimi pedis, 289. 
 
 digitorum pedis, 389 
 pollicis, 262. 
 
 ■ pedis, 287. 
 
 carpi radialis, 850. 
 ulnaris, 250. 
 
 longus digitorum pedis, 335. 
 
 pollicis, 253. 
 
 pedis, 886. 
 
 perforans, 251. 
 
 ' pedis, 285. 
 
 perforatus, 252. 
 
 pedis, 390. 
 
 profundus digitorum, 252. 
 
 sublimis digitorum 331. 
 
 frontalis, 230. 
 
 gastrocnemius, 281. 
 • gemellus inferior, 267. 
 superior, 267. 
 
 genio-hyoglossus, 338. 
 hyoideus, 229. 
 
 glosso-staphylinus, 332. 
 
 glutseus niaximus, 264. 
 
 medius, 265. 
 
 minimus, 266. 
 
 gracilis, 275. 
 
 helicis major, 667. 
 minor, 667. 
 
 Homer's, 653. 
 
 Houston's, 457. 
 
 hyo-glossus, 338. 
 
 iliacus, 215. 
 
 indicator, 260. 
 
 infra-costales, 232. 
 spinatus, 243. 
 
 intcr-costales externi, 222. 
 intemi, 222. 
 
 ■ ossei manAs, 263. 
 
 dorsales, 264. 
 
 ' palmares, 264. 
 
 ■ pedis dorsales, 290. 
 plantares, 290. 
 
 ■ spinales colli, 286. 
 
 ■ transversales colli, 917. 
 — lumborum, 218 
 
 ischio-bulbosus, 457. 
 
 in the female, 470. 
 
 cavernosus, 456. 
 
 in the female, 471. 
 
 coccygeus, 380. 
 
 latissimus dorsi, 198. 
 laxatOT tympani, 675. 
 levator anguli oris, 236. 
 
 scapulae, 201. 
 
 ani, 380. 
 
 labii inferioris, 237. 
 
 superioris, 236. 
 
 alasque nasi, 333 
 
 menti, 237. 
 oculi, 640. 
 
894 
 
 INDEX. 
 
 Muscles, levator palati, 332. 
 
 palpebrae superioris, 233, 648. 
 
 — — — — prostatae, 382. 
 
 UTulte, 337. 
 
 levatores costarum breviores, 222. 
 
 — longiores, 222. 
 
 Muscles, rectus oculi superior, 649. 
 retrahens auriculam, 230. 
 rhomboideus major, 200. 
 minor, 200. 
 
 lingualis (Albinus and Douglas), 337. 
 
 inferior, 337. 
 
 superficialis, 337. 
 
 - longissimus dorsi in tie loins, 208. 
 
 1 neck, 203. 
 
 • thorax, 203 
 
 -longus colli, 218 
 - lambricales manOs, 253. 
 • pedis, 290 
 
 accessory fibres to, 203, 204. 
 
 - mallei externus magnus, 673. 
 parvus, 673. 
 
 intemus, 674. 
 
 - masseter, 239. 
 
 - multifidus spins in the loins, 202, (note). 
 __ back, 203. 
 
 ■ neck, 204. 
 
 -mylo-hyoideus, 229. 
 -mjrrtiformis, 234. 
 
 - naso-labialis, 234. 
 
 - obliquus abdominis extemus, 208. 
 ■ intemus, 209. 
 
 - capitis inferior, 206. 
 superior, 206. 
 
 - oculi inferior, 651. 
 superior, 651. 
 
 - obturator extemus, 268. 
 ■ intemus, 267 
 
 occipitalis, 230. 
 occipito-frontalis, 230. 
 
 pharyngeus, 338. 
 
 - omo-hyoideus, 226. 
 
 - opponens digiti minimi, 262. 
 — poUicis, 260. 
 
 - orbicularis oris, 235. 
 
 ' palpebrarum, 231. 
 
 - palato-glossus, 332. 
 
 pharyngeus, 332. 
 
 staphylinus, 332. 
 
 -palmaris brevis, 261. 
 longus, 250. 
 
 - palpebralis, 231. 
 
 - patheticus, 651. 
 -pectineus, 275. 
 
 -■ — pectoralis major, 220. 
 minor, 221. 
 
 perforatus Casserii, 253. 
 peri-staphylinus extemus, 332. 
 intemus, 332. 
 
 peroneus brevis, 280. 
 
 longus, 280. 
 
 tertius, vel anticus, 279. 
 
 petro-pharyngeus, 348. 
 pharyngo-staphylinus, 332. 
 plantaris, 282. 
 platysma myoides, 224. 
 popliteus, 283. 
 pronator quadratus, 253. 
 
 radii teres, 249. 
 
 rotundas, 249. 
 
 psoas-iliacus, 214 
 
 magnus, 215 
 
 parvus, 216. 
 
 pterygoideus extemus, 241 
 internus, 240. 
 
 pterygo-pharyngeus, 347. 
 pubio-urethralis, 457. 
 pyramidalis abdominis, 212. 
 nasi, 233. 
 
 - pyriformis, 266. 
 
 - quadratus femoris, 268. 
 - lumborum, 216, 
 
 — meuti, 237. 
 
 - rectus abdominis, 210 
 
 capitis anticus major, 218. 
 
 - minor, 218. 
 
 lateralis, 217. 
 posticus major, 206. 
 minor, 206. 
 
 • femoris, 270. 
 
 intemus, 272. 
 
 • oculi extemus, 650. 
 
 internus, 650. 
 
 inferior, 650. 
 
 -risorius Santorini, 284. 
 
 - sacro-lumbalis, in the loins, 203. 
 
 in the thorax, 204. 
 
 on the chest, 204. 
 
 - salpingo-pharyngeus, 338. 
 ■sartorius, 272. 
 
 - scalenus anticus, 217. 
 
 posticus, 218. 
 
 -scalptor ani, 275. 
 
 scapulo-hyoideus, 226. 
 
 semi-spinalis colli, 204 (note). 
 
 dorsi, 204 (note). 
 
 ■ membranosus, 270. 
 ' tendinosus, 270. 
 
 - serratus anticus, 223. 
 
 - parvus, 223. 
 
 ■ magnus, 221. 
 - posticus inferior, 201 . 
 ■ superior, 201. 
 
 • soleus, 282. 
 - spheno-pharyngeus, 338. 
 ■ sphincter ani extemus, 380. 
 ■ intemus, 380. 
 
 (esophagi, 350. 
 vaginse, 470. 
 vesicae, 442. 
 
 -spinales posteriores, 201. 
 
 ■ action of, 203. 
 
 ' general view of, 203. 
 
 in the loins, 201. 
 
 neck, 204. 
 
 ' thorax, 204. 
 
 ■ spinalis dorsi, 204. 
 
 • cervicis, 204. 
 
 - splenius capitis, 202. 
 -colli, 202. 
 
 ■stapedius, 671. 
 
 ■ sterno-cleido-mastoideus, 224. 
 
 hyoideus, 226. 
 
 thyroideus, 227. 
 
 - stylo-glossus, 337. 
 
 hyoideus, 229. 
 
 alter, 230. 
 
 pharyngeus, 346. 
 
 - sub-clavius, 221. 
 scapularis, 244. 
 
 - super-ciliaris, 232. 
 
 ■ supinator radii brevis, 256. 
 longus, 254. 
 
 - supra-costales, 221. 
 
 spinatus, 243. 
 
 -suralis, 281. 
 
 - temporalis, 239. 
 
 - tensor palati, 332. 
 
 tarsi, or Homer's, 653. 
 
 tympani, 671. 
 
 vagina; femoris, 271. 
 
 - tensors of fasciae, 296. 
 
 - teres major, 198. 
 minor, 243. 
 
 - thyro-arytenoideus, 428. 
 
 epiglottideus, 428. 
 
 hyoideus, 227. 
 
 - tibialis anticus, 278. 
 - posticus, 284. 
 
 • trachelo-mastoideus, 204. 
 ■tragicus, 667. 
 
 ■ transversalis abdominis, 210. 
 -cervicis, 205. 
 
 — colli, 204. 
 - nasi, 234. 
 
 ■ transverso-spinalis, 202. 
 
 — in the loins, 202. 
 
 in the neck, 204. 
 
 in the thorax, 204 
 
 transversus auriculae, 667. 
 
 nasi, 234. 
 
 pedis, 290. 
 
 perinaei, 381. 
 
 ■ alter, 457. 
 
 ' pollicis pedis, 290. 
 
 -trapezius, 198. 
 
 - triangularis nasi, 234. 
 
 oris, 237. 
 
 stemi, 
 
 - triceps adductor femoria^ 274. 
 
INDEX. 
 
 Muscles, triceps extensor cruris, 273. 
 
 cubiti, 247. 
 
 femoralis, 272. 
 
 - femoris (auctor), 272. 
 
 suralis, 281. 
 
 - trochlearis, 651. 
 
 - of the ureters, 445. 
 
 vastus externus, 273. 
 
 intemus, 273. 
 
 Nerves, sensory, common, 759, 7fl8. 
 
 — special, 762. 
 
 spinal, 759. 
 
 structure of, 766. 
 
 symmetrical, 760. 
 
 sympathetic, 762, 764. 
 
 structure of, 767. 
 
 • Wilson's, 457. 
 
 - which move the arm upon the shoulder, 292. 
 
 fingers, 293. 
 
 foot upon the leg, 293. 
 
 forearm upon the arm, 293. 
 
 hand upon the forearm, 293. 
 
 leg upon the thigh, 292. 
 
 lower jaw, 292. 
 
 OS hyoides, 292. 
 
 pelvis, 292. 
 
 radius upon the ulna, 293. 
 
 ribs, 292. 
 
 : shoulder, 292. 
 
 skin, 293. 
 
 thigh upon the pelvis, 292. 
 
 toes, 293. 
 
 ■ vertebro-cranial column, 292, 
 
 — walls of thorax and abdomen, 
 
 292. 
 
 • zygomaticus major, 236. 
 ■ minor, 236. 
 
 Muscular fibres, filaments, and fasciculi, 198 (note). 
 fibres of particular organs. See those organs, 
 
 sheaths, 296. 
 
 tissue, involuntary, 198. 
 
 structure, 322. 
 
 voluntary, 198. 
 
 — — ^ chemical composition, 199. 
 
 structure, 198. 
 
 Musculi pectinati, 486. 
 
 papillares, 484. 
 
 Musculo-cutaneoMs nerves. See Nerves. 
 Myology, 190. 
 
 Nails, 636. 
 
 lunule of, 636. 
 
 matrix, 636. 
 
 structure and growth of, 637. 
 
 Nares, anterior, 60. 
 
 posterior, 60. 
 
 Nasal arteries. See Arteries. 
 bone, 55. 
 
 •■ cartilages. See Nose. 
 duct and canal, 653. 
 
 ■- eminence, 35. 
 
 fossie, 62. 
 
 meatuses, 41. 
 
 nerves. See Nerves. 
 
 process, 51. 
 
 spine, anterior and posterior, 82, 54. 
 
 Nates (of brain), 712. 
 Navicular fossae. See Fossa. 
 Necks of bones, 10. 
 
 particular. See those bones. 
 
 Nerves in general, 759. 
 
 anastomoses of, 762. 
 
 of animal life, 761. 
 
 central extremity of, 760. 
 
 classification of, 759. 
 
 course of, 762. 
 
 cranial, 759. 
 
 different kinds of, 761. 
 
 direction of, 763. 
 
 division of into sets, 769. 
 
 fibres and filaments of, 767. 
 
 ' ganglia of, 765. 
 
 connexions of, 765. 
 
 different kinds of, 765. 
 
 structure of, 768. 
 
 ganglionic, 764. 
 
 mode of division of, 764. 
 
 motor, 759. 
 
 neurilemma of, 766. 
 
 of organic life, 761. 
 
 origin of, apparent and real, 758. 
 
 plexuses of, 762. See Plexuses 
 
 preparation of, 769. 
 
 relations of, 763. 
 
 respiratory, 760, 762. 
 
 roots of, anterior or motor, 762. 
 
 posterior or sensory, 762. 
 
 termination of, 764. 
 in particular, 769. 
 abdominal, great, 798. 
 
 small, 799. 
 
 abducens oculi. See Motor Oculi, extemai. 
 accessory, of internal cutaneous, 785. 
 saphenous, 801. 
 
 ' obturator, 801 (note). 
 
 ' spinal, distribution of, 849. 
 
 function of, 851. 
 
 ■ ganglion of, 824. 
 
 — origin of, 823. 
 
 — vertebral course, 824. 
 
 acromial, 778. 
 alveolo-dental, anterior, 834. 
 posterior, 834. 
 
 anal cutaneous, 806. 
 
 aortic, sympathetic, 863. 
 
 articular of ankle, 812. 
 
 of elbow, 785, 786. 
 
 hip-joint, 800. 
 
 of knee, anterior, 802. 
 
 external, 808. 
 
 of wrist, 785. 
 
 auditory. See Portio Mollis. 
 auricular, anterior, 836. 
 ■ great, 778. 
 
 • internal, 812. 
 
 • from obturator, 801. 
 
 ■ recurrent, 809. 
 
 ■ posterior, or azygos, 6U. 
 
 of pneumogastric, 845. 
 
 ■ posterior, 840. 
 
 auriculo-occipital, 840. 
 ■ temporal, 836. 
 
 axillary, or circumflex, 783. 
 azygos, of knee-joint, 813. 
 buccal, 835. 
 
 of facial, 841. 
 
 bucco-labial, 835. 
 bulbo-urethral, 806. 
 calcaneal, external, 812. 
 ' internal, 813. 
 
 cardiac, great, 861. 
 
 inferior, left, 861. 
 
 right, 861. 
 
 lesser, 861. 
 
 middle, left, 862. 
 right, 861. 
 
 of pneumogastric, in neck, 647. 
 
 in thorax, 837. 
 
 • of recurrent laryngeal, 837. 
 
 — superficial, 861. 
 
 — superior, left, 861. 
 - right, 860. 
 
 of sympathetic, 860. 
 
 carotid branch of vidian, 833. 
 of sympathetic, 765. 
 
 cerebral. See Cranial. 
 
 cervical, branches of, anterior, 776, 781. 
 posterior, 773. 
 
 ■ number of, 771. 
 •roots of, 771. 
 
 cervical, first, anterior branch of, 776. 
 
 posterior branch of, 773. 
 
 second, anterior branch, 776. 
 
 posterior branch, 774. 
 
 — third, anterior branch, 777. 
 
 posterior branch, 774. 
 
 — fourth, anterior branch, 777. 
 posterior branch, 774. 
 
 — fifth to eighth, anterior branches, 781 
 
 posterior branches, 774 
 
 -of facial, 841. 
 
 — internal descending, 780. 
 
 — superficial, 778. 
 
 cervico-facial, 839, 841. 
 chorda tympani, 836. 
 
 . canal for, 672. 
 
 ciliary, 659, 830. 
 
 nasal, 830. 
 
 ophthalmic, 830. 
 
 circumflex, 782. 
 
«96 
 
 Nerves, clavicular, 783. "^''^ " ^ . W 
 
 of clitoris, 807. 
 
 for cochlea, 842. 
 
 collateral dorsal of fingers, 790. 
 
 . of thumb, 798. 
 
 of toes, 811. 
 
 palmar of fingers, 788, 790. 
 
 ■ thumb, 788. 
 
 rNDEX. 
 
 • comnmnicating fibular, 811. 
 tibial, 811. 
 
 for complexus, 773. 
 
 for coxo-femoral articulation, 800 (note). 
 
 cranial, in general, 816. 
 
 central, extremities of, 817. 
 
 classification of, 816. 
 
 distribution of, 832. 
 
 general view of, 853. 
 
 nomenclature of, 817. 
 
 cranial, in particular, 832. 
 first. See Olfactory. 
 
 second. See Optic. 
 
 third. See Motor UcuH, common. 
 
 fourth. See Pathetic. 
 
 fifth. See Trifacial. 
 
 sixth. See Motor Oculi, external. 
 
 seventh. See Portio Dura and Pord'o 
 
 Mollis. 
 
 eighth. See Pneumogastric, Glosso- 
 
 pharyngeal, and Spinal Accessory. 
 
 ninth. See Hypo-glossal. 
 
 crural, 801. 
 
 for crureus, 802. 
 
 cutaneous, accessory of saphenous, 801 . 
 
 — anal, 806. 
 
 external, of arm, 785. 
 
 ' of musculo-spiral, 791. 
 
 ■of thigh, 799. 
 
 • of intercostal, 794. 
 ■ internal, of arm, 784. 
 
 accessory of, 785. 
 
 of musculo-spiral, 791. 
 
 of thigh, 801. 
 
 ■ of Wrisberg, 785. 
 
 ■long, of obturator, 801 (note), 
 -middle, of thigh, 801. 
 • of musculo-cutaneous of arm, 785. 
 ■palmar, 787. 
 
 ■ perforating, of intercostal, 794. 
 of thigh, 803. 
 
 — plantar, 813. 
 
 — radial, 792. 
 
 — of shoulder, 784. 
 
 — of S(Emmering, 807. 
 
 — tibial, 803. 
 ■ ulnar, dorsal, 789. 
 
 deep palmar, 789. 
 
 ■ plantar, 814. 
 
 temporal, 835. 
 
 dental, anterior, 834. 
 
 inferior, 837. 
 
 posterior, 833. 
 
 descendens noni, 853. 
 
 descending cervical, 779. 
 internal, 777. 
 
 diaphragmatic, 780. 
 
 digastric, 840. 
 
 digital, of median, 788 
 of radial, 792. 
 
 of ulnar, 789. 
 
 dorsal, branches of, anterior, 794. 
 - posterior, 77S 
 
 ~ number of, 771. 
 
 — roots of, 772. 
 
 — collateral of fingers, 790, 792. 
 — toes, 8)1. 
 
 — of foot, deep external, 811. 
 — internal, 811. 
 
 — of hand, external, 792. 
 internal, 790. 
 
 — intercostal. See Intercostal. 
 
 — of penis, 806. 
 
 ■ dorsi-lumbar, 796. 
 
 - to dura mater, 835. 
 
 • encephalic. See Crtmidl. 
 
 ■ ethmoidal, 830. 
 
 ■ facial. See Portio Dvra. 
 
 branches, collateral, 839. 
 
 summary of, 848. 
 
 • to femoral artery, 802. 
 
 - frontal, 828. 
 
 Nerves, frontal, external, 829. 
 
 — internal, 829 
 
 — osseous, 829 
 
 - fronto-nasal, 829 (nole^ 
 
 - for gastrocnemius, 812. 
 
 - for gemelli, 808. 
 
 - genito-crural, 799 
 
 ■ glosso-pharyngeal, distribution of, 843. 
 
 function of, 845. 
 
 ganglion of, 844. 
 
 origin and cranial course, 
 
 823. 
 
 ■ gluteal, inferior, 807. 
 • superior, 807. 
 
 • gustatory, 836. 
 
 • hemorrhoidal, inferior, 806. 
 ■ to hip-joint, 800 (note), 
 -hypo-glossal, distribution, 851. 
 
 function, 853. 
 
 ganglion, 823. 
 
 origin and cranial course, 824 
 
 - ilio inguinal, 798. 
 
 scrotal, 798. 
 
 small, 798. 
 
 - incisor, 837. 
 
 • infra-hyoid, of hypo-glossal, 852. 
 
 orbital, 831, 841. 
 
 of facial, 841. 
 
 trochlear, 830. 
 
 ■ inguinal, external, 797. 
 ■ internal, 797. 
 
 ■ ingnino-cutaneous, 797. 
 
 ■ intercostal, 794. 
 
 muscular, 794. 
 
 perforating, 794. 
 
 summary of, 796. 
 
 ■ costo-humeral, 795. 
 
 ■ osseous, anterior, of forearm, 79d. 
 of leg, 811. 
 
 ■ posterior, of foreann, 790. 
 
 ■ ischiadic, 802. 
 
 lesser, 802. 
 
 ■ of Jacobson, 838. 
 
 ■ lachrymal, 828. 
 of orbital, 831. 
 
 lachrymo-palpebral, 888. 
 • laryngeal, anastomotic, 847. 
 
 external, 846. 
 
 inferior, or recurrent, 847. 
 
 superior, 846. 
 
 ' of sympathetic, 859. 
 
 ■ to latissimus dorsi, 784. 
 
 ■ levator angul i scapulae, 782. 
 • ani, 805. 
 
 ■ lingual, 836. 
 
 • of glosso-pharjmgeal, 844. 
 
 ■ longitudinal, of Lancisi, 737. 
 
 ■ lumbar, branches of, anterior, 796. 
 posterior, 776. 
 
 number of, 772. 
 roots of, 772. 
 
 ■ lumbo-sacral, 797. 
 ' malar, 831. 
 of facial, 840 
 
 ■ masseteric, 835. 
 
 ■ mastoid, great, 779. 
 ■ small, 780. 
 
 • maxillary, inferior, 834. 
 
 superior, 831. 
 
 terminal blanches of, 834L 
 
 ■ median, 786. 
 
 in arm, 786.^ 
 
 in forearm, 787. 
 
 ■ in hand, 787. 
 
 - mental, 837 
 
 of facial, 841. 
 
 ■ motor oculi, common, distribution of, 825. 
 function of, 826. 
 
 origin and cranial course, 
 
 820. 
 external, distribution, 838. 
 
 origin and cranial course. 
 
 822. 
 
 • musculo-cutaneous, brachial, 786, 
 
 . crural, 801. 
 
 — dorsal, 775. 
 
 ■ of leg, 810. 
 
 - lumbar, inferior, 798. 
 
 — middle, 798. 
 
 superior, 798 
 
INDEX. 
 
 Nerves, musuulo-spiral, 786, 791. 
 
 myloid, 837. 
 
 nasal, 829. 
 
 • external, 829. 
 
 internal, 830. 
 
 — — posterior, 832. 
 
 superior, 833. 
 
 ■ of nasal fossa, external, 830. 
 
 naso-lobar, 830. 
 
 palatine, 832. 
 
 obturator, 799. 
 
 accessory of, 800 (note). 
 
 articular of, to hip, 800. 
 
 ' knee, 801 (not«). 
 
 ' long cutaneous, 801 (note). 
 
 ■ to obturator iiitemus, 805. 
 
 ■ occipital, external, 779. 
 great, 777. 
 
 - small, 780. 
 
 ■ oculo-muscular. See Motor Oculi and Pathetic. 
 
 ■ oesophageal, 847. 
 
 ■ olfactory, bulb of, 817. 
 distribution of, 824. 
 
 function of, 825. 
 
 origin and cranial conrse, 818. 
 
 structure of, 818. 
 
 ■ ophthalmic, 827. 
 
 ■ optic, chiasma or commissnre of, 819. 
 
 distribution of, 825. 
 
 function, 825. 
 
 origin and cranial course, 819. 
 
 roots of, gray, 608. 
 
 ' structure, 820. 
 
 Nerves, popliteal, sciatic, external, 808. 
 internal, 811. 
 
 portio dura, distribution, 839, 
 
 function, 843. 
 
 "^ ■ origin and cranial course, 82S. 
 
 mollis, distribution, 681, 842. 
 
 function, 842. 
 
 origin and cranial course, 63S. 
 
 structure, 768. 
 
 • pterygoid, 833 
 
 internal, 836. 
 
 • pudendal, long, 808. 
 
 • pudic, internal, 806. 
 ■ in female, 807 
 
 pulmonary, anterior and posterior, 848. 
 
 to pyrifonnis, 807. 
 
 for quadratus femoris, I 
 
 — radial, or musculo-spiral, 790. 
 proper, 791. 
 
 — to rectus femoris, 802. 
 
 — recurrent, of knee, 810. 
 ^— ^— ^^— laryngeal, 648. 
 
 lesser sciatic, 8081 
 
 -- terminations of, 671. 
 tracts of, 819. 
 
 ■ orbital, 831. 
 
 of facial, 840. 
 
 ' palatine, anterior, 832. 
 
 middle, 832. 
 
 posterior, 832. 
 
 ■ palmar collateral, 769, 790. 
 ' cutaneous, 768. 
 
 • palpebral, inferior, 840. 
 ■ superior, 840. 
 
 of particular organs, parts, or tissues. See 
 
 those organs, &c. 
 
 par Tagnm. See Pneumogastric. 
 
 pathetic, distribution, 826. 
 
 function, 826. 
 
 origin and cranial course, 820. 
 
 to pectineus, 801 (note), 802 (note). 
 
 ■ pectoralis major, 783. 
 
 • minor, 783. 
 
 • perforans Casserii, 786. 
 ■ perforating, of hand, 790. 
 
 cutaneous, of inter-costalsj 
 
 thigh, 802. 
 
 ' perineal, 806. 
 
 superficial, anterior, 806. 
 
 posterior, 806. 
 
 - peroneal, 808. 
 
 cutaneous, 810. 
 
 external, 810. 
 
 saphenous, 810. 
 
 ' petrosal, superficial, great, 833. 
 
 small, 838. 
 
 ■ pharyngeal, of glosso-pharyngeal, 844. 
 ' pneumogastric, 646. 
 
 small, 846, 850. 
 
 of spheno-palatine, 833 (note). 
 
 sympathetic, 859. 
 
 ■ phrenic, 780. 
 
 ■ plantar, collateral, 813, 814, 
 external, 814. 
 
 ■ deep, 814. 
 
 internal, 813. 
 
 ' for plantaris longus, 812. 
 
 ' pneumogastric, in abdomen, 846. 
 
 anastomoses of, 845. 
 
 cranial course, 823. 
 
 fibrous layers of, 719. 
 
 in foramen lacerum, 645. 
 
 functions of, 849. 
 
 ganglion of, 845. 
 
 in neck, 845. 
 
 origin of, 823. 
 
 summary of, 849. 
 
 in thorax, 847. 
 
 ■ popliteal, external, 808. 
 internal, 812. 
 
 ■ renal, 865. 
 
 • respiratory, external, 782. 
 
 of eye, 891. 
 
 superior, of trunk, 850. 
 
 ■ to rhomboideus, 782 
 
 ■ sacral, branches of, anterior, 804. 
 posterior, 777. 
 
 — number of, 772. 
 roots of, 772. 
 
 ' saphenous, external, 812. 
 
 internal, 803. 
 
 accessory, of, 802 
 
 — peroneal, 810. 
 
 ' satellite, of femoral artery, 803. 
 • ulnar artery, 790. 
 
 ■ sciatic, great, 808. 
 lesser, 801. 
 
 ■ of septum nasi, anterior, 830. 
 posterior, 832. 
 
 ■ to serratus, ' 
 
 ■ of sheath of femoral vessels, SOS, 
 
 ■ soft (nervi molles), 845. 
 
 ■ spheno-palatine, external, 833. 
 — internal, 832. 
 
 • spinal, 770. 
 
 — accessory of Willis. 
 
 — branches of, in general, 771 
 
 anterior, 771. 
 
 ganglionic, 771. 
 
 posterior, 773. 
 
 See AcctMorf, 
 
 ■ classification of, 770. 
 
 ■ number of, 770. 
 • origin of, apparent, 770. 
 
 real, 772. 
 
 plexuses of, 776. 
 
 — roots of, anterior, or non-ganglionic, 77L 
 — roots of, posterior, or ganglionic, Til 
 
 ' splanchnic, great, 865. 
 
 lesser, 865. 
 
 lumbar, 869. 
 
 ■ splenic, 867. 
 - to splenius, 843. 
 
 ■ sternal cutaneous, 780. 
 • styloid, 840. 
 
 ■ to sub-clavius, 782. 
 
 ■ sub-occipital, anterior branch, 778. 
 • posterior, 776. 
 
 ■ scapular, inferior, 784. 
 superior, 783. 
 
 ■ of sub-septum, 841. 
 
 superficial cardiac, 862. • 
 
 cervical, 776. 
 petrosal, great, 633. 
 lesser, 637. 
 
 ■ temporal, 835. 
 
 • supra-clavicular, 779. 
 
 orbital, 828. 
 
 scapular, 782. 
 
 ' trochlear, 829. 
 
 5X 
 
 to supra and infra-spinati, 782. 
 
 sympathetic, in general, 761. 
 
 characters of, 871. 
 
 structure of, 766. 
 
 in particular, 854. 
 
 abdominal, 851. 
 
 I cervical, 855. 
 lumbar, 848. 
 
898 
 
 INDEX. 
 
 Nervei, sympathetic, sacral, 871. 
 
 — thoracic, 868. 
 
 temporal, deep, 835. 
 
 of facial, 839. 
 
 -- superficial, 836. 
 
 • temporo-facial, 839. 
 malar, 831. 
 
 ' to tensor tympani, 837. 
 
 vagins femoris, 807. 
 
 • tentorium cerebelli, ffl7. 
 ■ teres major, 874. 
 minor, 783. 
 
 • thoracic, 783. 
 
 anterior, 783. 
 
 — posterior,782. 
 
 -tibial, 811. 
 
 anterior, 811. 
 
 cutaneous, 802. 
 
 posterior, 811. 
 
 saphenous, 813» 
 
 • to trapezius, 781. 
 
 • trifacial, distribution of, 827. 
 
 divisions of, 827. 
 
 ganglion of, 821. 
 
 ' origin and cranial course, 821. 
 
 root of, large, 821. 
 
 small, 821. 
 
 ■trigeminal. See Tfifaeiat. 
 
 ■ trochlear. See Pathetic. 
 
 ■ tympanic, of Jacobson, 838. 
 • ulnar, 789. 
 
 in the arm and fo(re8rm> 789. 
 
 - hand, 790. 
 
 - for ulnar artery, 790. 
 
 - uterine, 870. 
 
 - vaginal, 870. 
 
 - for vasti femoris, 802. 
 
 - vertebral (sympathetic), 860. 
 
 ■ vesical, 870. 
 
 ■ vestibular, 843. 
 
 ■ vidian, 833. 
 
 ■ visceral, abdominal, 866. 
 
 cervical, 845. 
 
 pelvic, 869 
 
 ■ sacral, 805 
 
 Nervi moUes, 845. 
 
 Nervous system, central portion, 681. 
 
 peripheral portion, 769.1 
 
 Nervut impar, 698. 
 Neurilemma of nerves, 766. 
 
 spinal cord, 697. 
 
 Neurology, 629. 
 
 Ninth nerve. See Nerve, hypoglossal. 
 
 Nipples, 472. 
 
 glands and papillte of, 473. 
 
 Noduli Arantii, 479. 
 Nodulus of cerebellum, 716 (note). 
 Nodus encephali (Soemmering), 844- 
 Ncsud de I'encephale, 844. 
 Nost, general description, 641. 
 
 bones of, 55, 641. 
 
 cartilages of, 641. 
 
 mucous membrane of« MStt 
 
 ' muscles of, 643. 
 
 septum of, 56, 642. 
 
 skin of, 643. 
 
 Nostrils, 641. 
 
 cartilages of, 641. 
 
 Notch, inter-cocSyloid, 91. 
 
 ischiatic, 89. 
 
 -—^— sacro-sciatic, 89. 
 
 great, 15S. 
 
 small, 156. 
 
 sciatic, 89. 
 
 ' sigmoid, 57. 
 
 Notches, vertebral, 20, 31. 
 Nutritious arteries. See Arteries. 
 
 foramina of bones. See Fontmen. 
 
 Nympha, 471. 
 
 ■Obligue muscles. See Musclet. 
 'Obturator foramen and groove, 88. 
 
 nerve. See Nerves. 
 
 ' Occipital angle of DaubentOB, 45. 
 
 bone, 33. 
 
 condyles, 33< 
 
 crests, 34. 
 
 foramen, 34. 
 
 fossae, 34. 
 
 ' nerves. See iVerM*. 
 
 Occipital protuberances, 34. 
 veins. See Veins. 
 Occt7>ito-atlantoid articulations, 118 
 ligaments, 118. 
 
 ' axoid articulations, 119. 
 ' ligaments, l20. 
 
 parietal suture, 46, 
 OcuZo-muscular nerves. See Nenitt, Motwr Oaii tad 
 
 Pathetic. 
 Odontoid process, 26. 
 Odontogeny, 184. 
 Odontology, 177. 
 (Esophagus, 350. • 
 
 glands of, 352. 
 
 ihooous membrane, 352. 
 
 muscular coat, 351. 
 
 structure of, 351. 
 
 uses, 352. 
 
 vessels and nerves, 3S3, 
 OUcranoid cavity, 80, 
 Olecranon process, 80. 
 Olfactory nerve. See Nervtt 
 
 ■ lobes, 758. 
 
 Olivary process, 37, 
 bodies, 703. 
 
 corpus dent&taiB of, 704. 
 
 sections of, 704. 
 
 structure of, 706. 
 
 fasciculi, 705. 
 
 Omentum, colic, 478 (note). 
 - gastro-colic, 478. 
 
 hepatic, 476. 
 
 — splenic, 408. 
 
 ■ great, 476. 
 
 layers of, anterior, 476. 
 
 -posterior, 476. 
 
 «ac of, 477. 
 
 vessels and nerves of, 478. 
 
 lesser, 476. 
 
 layer of, anterior, 476. 
 
 posterior, 476. 
 
 Operculum laryngis, 426, 
 Ophthalmic nerve, 828. 
 Optic thalami, 727, 745. 
 
 fibres of, 746, 
 
 tracts, 820. 
 
 Orbicular ligaments of joints.- See Ligaments. 
 Orbital arch, 36. 
 cavities, 6 
 fissure, 53. 
 
 foramina, internal, 36. 
 process of palate bone, 6S. 
 processes of frontal bone, 36. 
 plate, 36. 
 Orbits, 62. 
 
 Organ of hearing, 665. See Ekir. 
 sight, 645, See Eye. 
 
 smell, 641, See Nose, &aA Pituitary Mttnbrcoi*. 
 taste, 639. See Tongue. 
 touch, 629. See Skin. 
 the voice, 422. See Larynx. 
 Organs, anatomical elements of, 320. 
 colour and consistence of, 321. 
 development of, 321, 
 of digestion, 322, 
 direction and relations of, 3S1. 
 dissection of, 322, 
 functions of, 322, 
 of generation, female, 46], 
 male, 446. 
 
 genito-urinary, 435, 
 nomenclature, 320, 
 number, 320. 
 of respiration, 409. 
 of the senses, 629. 
 situation, 320. 
 size and figure, 321. 
 structure of, 321. 
 urinary, 435. 
 Os, bone. See Bone, oi. 
 tincsE, 465. 
 uteri, 465. 
 Ossa pisiformia, or lingualia. 111. 
 
 triquetra, or Wormiana, 50. 
 
 Ossicula auditOs, 669. 
 
 movements of, 675. 
 muscles belonging to, 674. 
 
 Ossification of bones. See those bones 
 Osteology, 5. 
 Osteogeny, 16. 
 
INDEX. 
 
 899 
 
 Ottia of Fallopian tube, 463. 
 Ottium internum of uterus, 465. 
 Otoconia and otolithes, 843. 
 Ova of Naboth, 466. 
 Ovarian vesicles, 463. 
 Ovaries, 461. 
 
 • ligaments of, 461. 
 
 - structure, 463. 
 
 Ovum, 462 
 
 Palate, bone, 53. 
 
 hard, 330. 
 
 development, 330. 
 
 structure, 330. 
 
 uses, 330. 
 
 soft, 330. 
 
 - aponeurosis of, 331. 
 ————— development of, 333. 
 
 glands of, 333. 
 
 — — — — mucous membrane of, SSS. 
 
 muscles of, 331, 
 pillars of, 331. 
 
 ■ structure of, 331 
 
 — uses of, 331. 
 — vessels, &c., of, 333. 
 
 Palatine aponeurosis, 331. 
 
 arch, 329. 
 
 canals, 52, 54. 
 
 accessory, 53, 54. 
 
 glands, 330. 
 
 • process, 52. 
 
 Palm of hand, 83. 
 
 Palmar arteries. See Arteries. 
 
 ligaments. See Ligament*. 
 
 nerves. See Nerve*. 
 
 Pancreas, 400. 
 
 development of, 409. 
 
 duct of, 402. 
 
 function of, 402. 
 
 lesser, 402. 
 
 structure of, 401. 
 
 1 vessels and nerves of, 408. 
 
 Panniculus adiposus, 629. 
 
 camosus, 629. 
 
 Papula, conjunctival, 648. 
 
 dental, 181. 
 
 (Goodsir), 183. 
 
 of kidney, 437. 
 
 — — — lachrymal, 646. 
 
 of skin, 630. 
 
 ~ of small intestine, 367. 
 
 of stomach, 361. 
 
 of tongue, 333. 
 
 Par vagum. See Nerve, pneumogoitric 
 Parietal bone, 41. 
 
 foramen, 41. 
 
 ■- fossa, 41. 
 
 protuberance, 41. 
 
 Parotid dnct, 341. 
 
 gland, 340. 
 
 development of, 340 (note). 
 
 structure of, 340. 
 
 Pars mastoidea of temporal bone, 43. 
 
 petrosa of temporal bone, 43. 
 
 squamosa of temporal bone, 43. 
 
 Patella, 95. 
 
 ligament of, 97. 
 
 Pathetic nerve. See Nerve*. 
 
 Patte d'oie, 270, 271. 
 
 Peduncles of cerebellum and cerebram. 
 
 gans. 
 Pelvis, aponeuroses of, 306. 
 
 articulations of, 154. 
 
 •^—^ axes of, 90. 
 
 • circumferences of, 92. 
 
 • compared with shoulder, lOS. 
 . development of, general, 93. 
 
 ' in general, 90, 
 
 ■ great or false, 90. 
 
 of the kidney, 439. 
 
 : structure of, 439. 
 
 little or true, 90. 
 
 brim of, 92. 
 
 strait, superior, 92, 
 
 ■ inferior, 92. 
 
 See those or- 
 
 mechanism of, 158-159. 
 regions of, 90. 
 ' varieties of, sexual, 90. 
 
 excavation or cavity of, 12S. 
 outlet of, 92. 
 
 Penis, 454. 
 
 corpus cavemosum of, 455. 
 
 glans of, 461. 
 
 ligament, suspensory or triangular, 45A 
 
 muscles of, 457. 
 Perforated spot, anterior, 734. 
 
 ■ posterior, 730. 
 
 Perforating arteries. See Arteries. 
 nerves. See Nerve*. 
 
 Pert-cardium, 494. 
 
 structure, 494. 
 vessels, 495. 
 
 Peritoneum, 474. 
 
 folds of, 478. 
 
 general description of, 478. 
 
 portion of, parietal, 478. 
 
 sub-umbilical, 474. 
 
 supra-umbili(^, 474 
 
 visceral, 477. 
 
 structure of, 479. 
 Permanent teeth. See Teeth. 
 Perone, 98. 
 
 Peroneal arteries. See Arteries. 
 See Nerve*. 
 
 Pes accessorius, 746. 
 
 hippocampi, 745. 
 
 Petrosal nerves. See Nerves. ^ 
 Petrous portion of temporal bone, 4S. 
 process, 43. 
 
 ' glottis, 640. 
 • lymph, 679. 
 ' osteum, 296. 
 
 ' alveolo-dental, 338. 
 
 Pharyngeal nerves. See Nerve*. 
 Pharynx, 344. 
 
 aponeuroses of, 346. 
 
 development of, 349. 
 
 mucous membrane of, 319. 
 
 muscles of, 346. 
 
 extrinsic, 346. 
 
 intrinsic, 346. 
 
 supernumerary, 346. 
 
 uses, 349. 
 
 vessels and nerves, 349. 
 Pia mater, 692. 
 
 cerebral, 692. 
 
 spinal, or rachidian, 697. 
 
 Pigmentum of skin, 632 (note) 
 eye, 659, 
 
 Pillar of valve of Vieussens, 712. 
 Pillars of diaphragm, 212. 
 
 - fauces, or palate, 331. 
 fornix, 740. 
 
 Pineal gland or body, 742. 
 
 - commissure and peduncles of, 743. 
 
 - concretions, 743. 
 function of, 744. 
 
 Pisiform bone, 83. 
 
 Pt<utM, 749. 
 
 Pituitary body or gland, 729. 
 
 - fossa, 37. 
 
 — membrane, 643. 
 
 follicles of, 645. 
 
 nei ves of, 645. 
 
 structure, 644. 
 
 vessels of, 645. 
 
 Plantar ligaments. See Ligaments. 
 nerves. See Nerves. 
 
 Plaques gaufries, '. 
 
 Plate, cribriform, of ethmoid bone, 40. 
 
 - horizontal, of palate bone, 53. 
 
 - orbital, 35. 
 
 - perpendicular, of ethmoid bone, 41. 
 
 Pleura, costal, diaphragmatic, mediastinal, and polnto 
 nary, 413. 
 
 structure and uses of, 413. 
 
 Pleura:, 413. 
 
 Plexuses of lymphatics, 614. 
 
 of nerve, 762, et infra. 
 
 auricular, 858. 
 
 brachial, 781. 
 
 general view Ofnerrei of, 79S> 
 
 ' bronchial, 848. 
 • cardiac, deep, 860. 
 great, 863. 
 
 ' carotid, 856. 
 
 ■ superficial, 862. 
 
 — cavernous, 856. 
 
 — cervical, 777. 
 deep, 777. 
 
900 
 
 INDEX. 
 
 Plexuses, cervical, posterior, 774. 
 
 superficial, 777. 
 
 — ■^-— cervico-brachial, 77(i 
 
 coeliac, 866. 
 
 coronary, of heart, anterior and posterior, 863, 
 
 of stomach, 866. 
 
 ' diaphragmatic, I 
 ' epigastric, 866. 
 ' facial (sympathetic), 858. 
 ' gastro-epiploic, left, 868. 
 • right, 867. 
 
 — hemorrhoidal, inferior, 890. 
 snporior, 868. 
 
 ■ hepatic, 867. 
 
 • hypogastric, 870. 
 
 ■ infra-orbital, 841. 
 
 • laryngeal, 846. 
 ' lingual, 858. 
 
 ' lymphatic, 612, 
 
 . lumbar, 797. 
 
 ' lumbo-aortic, 868, 869. 
 
 sacral, 776. 
 
 ' mental, 837. 
 ' mesenteric, inferior, 868. 
 superior, 867. 
 
 ■ nervous, 762. 
 
 ■ occipital, 859. 
 
 ■ ovarian, 868. 
 
 • pharyngeal, 846, 859. 
 
 • phrenic, 866. 
 
 ■ pulmonary, anterior and poBtraior, 848. 
 
 • renal, 868. 
 
 ■ sacral, 805. 
 
 • solar, 866. 
 
 ■ spermatic, 868. 
 
 ■ splenic, 867. 
 
 ' supra-renal, 866. 
 
 • thyroid, 858. 
 
 • tympanic, 843. 
 
 • uterine, 870. 
 ' vertebral, 860. 
 
 vesical, 870. 
 
 visceral of abdomen, 866. 
 
 pelvis, 805, 869 
 
 ■ of veins, 575, et infrd. 
 alveolar, 589. 
 choroid, of brain, 747. 
 
 fourth ventricle, 730. 
 
 ■ third ventricle, 741. 
 - reflected portion of, 746. 
 
 ■ hemorrhoidal, 601. 
 
 ■ intra-spinal, 609. 
 
 • lingual, 590. 
 
 ■ masseteric, 590. 
 
 • pampiniform, 598. 
 ' pharyngeal, 591. 
 
 • pterygoid, 590. 
 
 ■ spermatic, 598. 
 
 ' spinal, deep, 609. 
 ■ longitudinal, 609. 
 
 - transverse, 609. 
 
 ' tonsillar, 333. 
 ' uterine, 602. 
 ' vaginal, 60S. 
 ■ vesico-prostatic, 601. 
 urethral, 602. 
 
 Plica semilunaris, 648. 
 Pneumo-gastric nerve. See Nene. 
 Pomum Adami, 424. 
 Pons Varolii, or cerebelli, 710. 
 
 internal structure rf, 718. 
 
 Porta, 388. 
 
 Portia dura nerve. See Nerve. 
 
 mollis nerve. See Nerve. 
 
 Prepuce, 454. 
 
 of clitoris, 471. 
 
 frcenum of, 454. 
 
 Process, acromion, 76. 
 
 auditory, 44. 
 
 basilar, 34. 
 
 cochleariform, 44, 673. 
 
 - coracoid, 76. 
 — — — coronoid, of lower jaw, 58. 
 
 of ulna, 80. 
 
 ensiform, 65. 
 
 of fifth metatarsal bone, 104. 
 
 ' genial, 58. 
 
 — gracilis of Raw, 673. 
 
 — hamular, of sphenoid bone, 37. 
 of cochlea. 678. 
 
 Process, of helix, 667. 
 
 ■ malar, 51. 
 
 ■ mastoid, 43. 
 
 ■ mental, 58. 
 
 ■ nasal, 51. 
 
 ■ odontoid, 26. 
 ' olecranon, 80. 
 
 — olivarv, 37. 
 
 — orbital, external, 36. 
 ■ internal, 36. 
 
 — of palate bone, M. 
 
 palatine, 52. 
 ' petrous, 43. 
 ' pyramidal, 54. 
 ' scaphoid, 101. 
 ' styloid, of temporal bone, 4S. 
 
 ulna, 80. 
 
 ■ radius, 81. 
 
 fibula, 99. 
 
 ' vaginal, of temporal bone, 44. 
 
 — vermiform, inferior, 716. 
 ■ superior, 716. 
 
 ' zygomatic, of temporal bone, 43. 
 of malar bone, 55. 
 
 Processes of bones, 9. 
 
 ciliary, of choroid coat, 656. 
 
 vitreous humour, 661 
 
 calcaneal, 101. 
 clinoid, 37. 
 pterygoid, 37. 
 spinous, of ilium, 89. 
 spinous, of vertebne, 21. 
 Processus a cerebello ad meduUam, 704. 
 
 pontem, 721. 
 
 testes, 711. 
 
 ' a cerebro ad meduUam, 710. 
 • arciformes, 703. 
 — gracilis of Raw, 673. 
 
 Profunda artery. See Arteries. 
 vein. See Veins. 
 
 Promontory of sacrum, 26, 92. 
 
 tympanum, 671. 
 
 Pronator muscles. See Musclet, 
 Protuberances, occipital, 34. 
 parietal, 42. 
 Psalterium, 738. 
 Pterygoid canal, 37. 
 
 columns, 126. 
 
 fossa, 37. 
 
 processes, 37. 
 
 P/ery^o-maxillary fissure, 52. 
 palatine canal, 38, 52. 
 
 Pubes, 90. 
 
 Pubic arch, 89. 
 
 Pudic arteries. See Arteries. 
 
 Pulmonary arteries. See Arteries. 
 
 veins. See Veins. 
 
 Puncta lachrymalia, 647. 
 Pupil of eye, 657. 
 Pupillary membrane, 659. 
 Pyloric valve, 355. 
 Pylorus, 354. 
 
 antrum of, 354. 
 
 Pyramid of cerebellum, or of Malacame, 717. 
 
 of tympanum, and its canal, 671. 
 
 Pyramids, anterior, 703. 
 
 decussation of, 706. 
 
 sections of, 706. 
 
 ■ of kidney, 437. 
 
 posterior, 704. 
 
 sections of, 706. 
 
 Quadrati muscles. See Muscles. 
 
 Rachis. See Vertebral Column. 
 
 Rachidian bulb, proper. See Medulla Oblongata. 
 
 bulbs, 697. 
 
 veins. See Veins, spinal. 
 
 Radial nerve. See Nerve. 
 Radiating crown of Reil, 744. 
 Radius, 81. 
 
 ^ and tibia, lower parts of, compared, 107. 
 
 Ra/ni of lower jaw, 57. 
 Ramus of pubes, 90. 
 
 ischium, 91. 
 
 Receptaculi arteriie, 525. 
 Receptaculum chyli, 618. 
 
 ganglii petrosi, 843. 
 
 Recess of tympanum, 672. 
 Recessvs sulciformis, 676. 
 
INDEX. 
 
 901 
 
 Recti muscles. See Muteltt, 
 Rectum, 376. 
 
 columns of, 377. 
 
 curves of, 377. 
 
 ■ internal surface, 378. 
 
 muscular coat of, 377. 
 
 structure of, 377. 
 
 Recurrent arteries. See Arteriet. 
 
 nerves. See Nerves. 
 
 Renes. See Kidneys. 
 
 succenturiati. See Supra-renal Capsules. 
 
 Respiratory apparatus, 409. 
 
 nerves, in particular. See Nerves. 
 
 Restiform bodies, 704. 
 Rete of Malpigbi, 640. 
 
 mucosum, 640. 
 
 of tongue, 646. 
 
 yasculosum testis, 451. 
 
 Reiia mirabilia, 496. 
 Retina, 660. 
 
 artery of, 660. 
 
 folds of, 660. 
 
 foramen centrale, and limbnt Inteua of, 660. 
 
 • margo dentatus, 660. 
 
 structure of, 660 (note). 
 
 termination of, 660 (note). 
 
 Ribs, angles of, 68. 
 
 characters of, general, 67. 
 
 — special, 68. 
 
 false, 67. 
 
 movements of, 134. 
 
 supernumerary, 32. 
 
 true, 67. 
 
 torsion of, 67. 
 
 tubercle of, 68. 
 
 Rima glottidis, 434. 
 
 palpebrarum, 646L 
 
 Ring, crural, 310. 
 
 inguinal, 310. 
 
 umbilical, 308. 
 
 Rostrum of cochlea, 676. 
 
 of corpus callosum, 787. 
 
 Rotula, 95. 
 
 Rugee, vaginal, 468. 
 
 Sac, lachrymal, 652. 
 Sacculus vestibuli, 680. 
 
 or sinus laryngis, 434. 
 
 Sacral arteries. See Arteries. 
 
 canal, 27. 
 
 foramina, 27. 
 
 nerves. See Nerves. 
 
 vertebne. See Vertebra and Vertebra.. 
 
 Socro-coccygeal vertebne, 26. 
 
 sciatic notch, 92. 
 
 vertebral angle, or promontory, 90. 
 
 Sacrum, 26. 
 
 promontory of, 26. 
 
 — — — small comua of, 27. 
 Saliva, 396. 
 Salivary glands, 340. 
 Saphenous nerves. See Nerves, 
 Satellite arteries. See Arteries. 
 
 • — nerves. See Nerves. 
 
 Scaphoid bone of carpus, 83. 
 
 of tarsus, 101. 
 
 ' process, 101. 
 Scapula, 75. 
 
 Scapular arteries. See Arteries. 
 Schindylesis, 114. 
 Sciatic notch, 89. 
 
 spine, 89. 
 
 Scrobiculis cordis, 354, 482. 
 
 Scrotum, 447. 
 
 Second cranial nenre. See Nerve, optic. 
 
 Sella turcica, 37. 
 
 Semen, 453. 
 
 Semi-circular canals, and their ampulle, 677. 
 
 membranous, 680. 
 
 lines of occipital bone, 33. 
 
 lunar bone, 83. 
 
 ■ ganglion, of fifth nerve, 843. 
 
 Seminiferous tubes, 454. 
 
 Septa, inter-muscular, 294. 
 
 — ^— — ^-^— — ^— — of arm, 315. 
 
 of thigh, 306. 
 
 Septum crarale, 303. 
 
 of dartos, 446. 
 
 inter-auricular, 482. 
 
 Seytum, inter-ventricular (of brain), 518. 
 (of heart), 481 
 
 • lucidum, 738. 
 
 layers of, 738. 
 
 ventricle of, 738. 
 
 nasal, artery of, 518. 
 
 cartilaginous, 642. 
 
 osseous, 56, 62. 
 
 pectiniforme, 454, 
 
 Serrati muscles. See Muscles. 
 Sesamoid bones, 96. 
 
 of hand, 153. 
 
 of foot, 177. 
 
 of gastrocnemius, 164. 
 
 Seventh cranial nerve. See Nerve, Portio Dura, aiui 
 
 Portio Mollis. 
 Sheath of brachial vessels, 316. 
 
 - femoral vessels, 310. 
 
 - for muscles, 296. 
 of arm, 316. 
 
 thigh, 311. 
 
 ■ synovial, 178. 
 
 ■ for tendons, 397. 
 around carpus, 319. 
 
 - - tarsus, 314. 
 
 • for vessels, 396. 
 
 ' structure of, 397. 
 
 Shoulder, aponeuroses of, 315. 
 
 bones of, 73. 
 
 compared -with pelvis, 105. 
 
 development of, general, 77. 
 
 in general, 77. 
 
 Sigmoid cavities, great and small, 80. 
 
 - flexure, 371. 
 
 - notch, 57. 
 
 - valves, 484. 
 
 Sinus, or sinuses, aortic, 498. 
 
 basilar, 587. 
 
 of bones, 1 1 . 
 
 of bulb of urethra, 459. 
 
 cavernous, 587. 
 
 circular, of Ridley, 588. 
 
 common, of vestibule, 680. 
 
 confluences of, 588. 
 
 ■ coronary, of heart, 577. 
 
 of Ridley, 587. 
 
 of dura mater, 583. 
 
 ethmoidal, 43. 
 
 frontal, 36. 
 
 of internal jugular, 583 
 
 lateral, or transverse, 584. 
 
 of larynx, or sinus of Morgagui, 584- 
 
 longitudinal, inferior, 586. 
 
 superior, 584. 
 
 — maxillary, 52. 
 -^ of Morgagni, 461. 
 
 — occipital, anterior, 587. 
 posterior, 587. 
 
 ' ophthalmic, 587. 
 ' petrosal, inferior, 586. 
 superior, 566. 
 
 — prostatic, 459. 
 
 — sphenoidal, 40. 
 
 — straight, 585. 
 
 — transverse, or lateral, 984. 
 
 — of urethra, 459. 
 
 — uterine, 602. 
 >- of Valsalva, 498. 
 
 — of veins, 575. 
 
 — of vena ports, 599. 
 
 — venosus (heart), 492. 
 Sixth cranial nerve. See Nerve. 
 Skeleton, general view of, 5. 
 
 natural, 5. 
 artificial, 5. 
 
 Skin, 629. 
 
 appendages of, 635. 
 characters, external, 629. 
 Spine, cutis or dermis of, 630. 
 
 epidermis of, 632 (note). 
 
 follicles, sebaceous, 627. 
 
 functions of, 627. 
 
 glands, sudoriferous, 632. 
 
 lymphatics of, 631. 
 
 papilla of, 639. 
 
 pigmentum of, 631, 632 (note). 
 
 pores of, 632. 
 
 rete mucosum, 633 (note). 
 
 structure of, 630-634. 
 
 true, 630. 
 
^P^2 
 
 Skull, 33 See Cranium and Face. 
 
 Socio parotidis, 341. 
 
 Sole of foot, 102. 
 
 Solitary glands. See Glands. 
 
 Space, inter-peduncular, 711, 728. 
 
 Spaces, inter-costal, 71. 
 
 osseous, hand, 84. 
 
 foot, 106. 
 
 INDEX. 
 
 ' sub-arachnoid, 688. 
 
 Sphenoidal cells, or sinuses, 39. 
 
 fissure, 39. 
 
 Sphenoid bone, 37. 
 S;)Aeno-frontal suture, 47. 
 
 jugal suture, 47. 
 
 maxillary fissure, 39, 5S. 
 
 ' fossa, 60. 
 
 ■ occipital bone, 36. 
 ~ suture, 47. 
 
 palatine foramen, 54. 
 
 parietal suture, 47. 
 
 spinous foramen, 39. 
 
 temporal fossae, 48. 
 
 suture, 47. 
 
 Sphincter muscles. See Muscles. 
 
 Spinal accessory nerre. See Nerve, accessory. 
 
 arteries. See Arteries. 
 
 cord, 693. 
 
 — ■ arachnoid of, 690. 
 
 enlargements of, cervical, lumbar, and oc- 
 cipital, 697. 
 ■ enveloped in its proper membrane, 697. 
 
 extent and situation of, 694. 
 
 form, direction, and relations of, 696. 
 
 furrows or grooves, 698. 
 
 — ^— — ^— membrane proper, or neurilemma of, 697. 
 
 pia mater of, 697. 
 
 ■ sections of, 700. 
 
 structure of, internal, 700. 
 
 examined by hardening, 702. 
 
 ■ sections, 700. 
 
 water, 701. 
 
 substance, gray and white, 702. 
 
 • minute structure, 702 (note). 
 
 • ventricles of, 702. 
 
 See Vertebral Column. 
 
 muscles, posterior. See Muscles. 
 
 nerves. See Nerves. 
 
 veins and plexuses. See Veirts. 
 
 Spine, nasal, anterior, 52. 
 
 posterior, 54« 
 
 of ischium, 89. 
 
 of pubes, 89. 
 
 of scapula, 75. 
 
 sciatic, 89. 
 
 or spinal column, 18. 
 
 of tibia, 97. 
 
 Spinous foramen of sphenoid, 39. 
 
 processes of ilium, 89. 
 
 of vertebrsE, 19, 31. 
 
 Splanchnic nerves. See Nerves. 
 Splanchnology, 320. 
 Spleen, 403. 
 
 cells of, 405. 
 
 coats of, 405. 
 
 • corpuscules of, 407. 
 
 development of, 407. 
 
 • fissure, or hilus, 405. 
 
 functions, 408. 
 
 lymphatics of, 407. 
 
 size of, differences in, 403. 
 
 ■ structure of, 405. 
 
 vessels and nerves, 405, 408. 
 
 Spleens, supernumerary, 403. 
 Splenic artery, 406. 
 
 omentum, 405. 
 
 veins, 406. 
 
 Spongy bones. See Bone*. 
 Stapes, 674. 
 Stenonian duct, 341. 
 Sternum, 64. 
 Stomach, 352. 
 
 alveoli of, 361. 
 
 coat of, cellular or fibrous, 357. 
 
 mucous, 356. 
 
 muscular, 356. 
 
 nervous (so called), 356, 
 
 - serous, or peritoneal, 357. 
 
 culs-de-sac of, 354. 
 
 curvatures of, 354. 
 
 development of, 361. 
 
 extremities of, 354. 
 
 Stomach, follicles of, 360. 
 function, 361. 
 glands of, 360. 
 granular appearance of, 397. 
 
 ' lymphatic system of, 360. 
 ' orifices of, 355. 
 ' papillse or villi, 359. 
 ■ structure of, 356. 
 ' surface of, external, 353. 
 ' internal, 355. 
 
 tuberosity of, 355. 
 
 tubnli of, 360. 
 
 vessels and nerves of, 360. 
 Structure of tissues and organs. See those organs and 
 
 tissues. 
 Styloid bone, 43. 
 
 process of temporal bone, 43. 
 
 fibula, 99. 
 
 radius, 81. 
 
 ulna, 80. 
 
 Sui-arachnoid fluid, 690. 
 
 uses of, 692. 
 
 ■ space, cranial, anterior, 688. 
 ' posterior, 686. 
 
 spinal, 689 (note). 
 
 lingual fossa, 58. 
 
 gland, 343. 
 
 ducts of, 343. 
 
 maxillary fossa, 58. 
 
 gland, 342. 
 
 duct of, 342. 
 
 synovial adipose tissue, 113. 
 
 Sulci. See Cerebrum, anfractuositiet of. 
 Super-ciliary foramen, 36. 
 
 ridge, 35. 
 
 Superficial petrosal nerves. See Nerves. 
 Supplementary cavity of shoulder-joint, 139. 
 
 of temporo-maxillary joint, 138. 
 
 Supro-orbitary foramen, 36, 59. 
 
 renal capsules, development of, 445. 
 
 structure, 446. 
 
 sphenoidal fossa, 37. 
 
 spinous fossa, 76. 
 Sustentaculum tali, 101. 
 Suture, coronal, or fronto-parietal, 45, 47. 
 
 ethmoido-frontal, 48. 
 
 ethmo-sphenoidal, 48. 
 
 fronto-jugal, 48, 59. 
 
 maxillary, 59. 
 
 nasal, 59. 
 
 sphenoidal, 48. 
 
 lambdoidal, or occipito-paxiet^, 40. 
 
 maxiUary, 59. 
 
 palatine, 60. 
 
 petro-occipital, 47. 
 sphenoidal, 48. 
 
 ■ sagfittal or bi-parietal, 46. 
 
 ■ spheno-frontal, 47. 
 
 jugal, 47. 
 
 parietal, 47. 
 
 temporal, 48. 
 
 ■ squamous, 47. 
 
 ■ temporo-parietal, 47. 
 
 ■ transverse or spheno-occipital, 46, 49. 
 
 Sutures, 114. 
 
 indented, squamous, and harmonic, 114. 
 
 cranial, in general, 154. 
 Sympathetic ganglia in particular. See Ganglia^ 
 
 nerves. See Nerves. 
 
 plexuses, in particular. See Plexuset, 
 
 system, in particular. See Ganglia and 
 
 Nerves. 
 Symphyses, characters of, 114. 
 Sympftysis menti, 57. 
 
 pubis, 89, 155. 
 
 sacro-iliac, 155. 
 
 Synarthroses, 114. 
 
 characters, ligaments, and motioni, llSk 
 
 Synchondroses, 113. 
 Syndesmology, 111. 
 Syneuroses, li3. 
 Synovia, 112. 
 Synovial bnrsae, 178. 
 
 capsules, 113. 
 
 of particular joints. See thov joints 
 
 ' fringes, 112. 
 
 ■ in the knee, 164. 
 
 ■ glands (so-called), 112. 
 membranes, articular, general characters of, 
 112. 
 
INDXX. 
 
 903 
 
 Synovial membranes, bursal, 178, 298. 
 
 ■ minute structure of, 178. 
 
 vaginal, 178, 299. 
 
 sheaths for tendons, 178, 298. 
 
 Syssarcostf, 114. 
 
 Taenia hippocsunpi, 746. 
 
 semicircularis, 740, 745. 
 
 Tarsus, bones of, 99. 
 
 • first row of, 100. 
 
 • ^_^____ compared with first row 
 
 of carpus, 107. 
 -^————— second row of, 101. 
 ' compared with second 
 
 row of carpus, 107. 
 
 ■ compared with carpus, 108, 
 
 sheaths for tendons on, 313. 
 
 Teeth, 177. 
 
 arteries of, 182. 
 
 bicuspid, 179. 
 
 bulbs of, 181. 
 
 canine, 180. 
 
 cement of, 182. 
 
 changes in, after eruption, 190. 
 
 ■ characters of, general, 179. 
 
 — differential, 179. 
 
 classification of, 178. 
 
 compared with bones, 183 (note). 
 
 epidermoid appendage*, 177. 
 
 - compound, 182. 
 
 - conformation of, external, 179. 
 — internal, 181. 
 
 - cortical portion of, 181. 
 substance of, proper, 182. 
 
 ■ crowns of, 179. 
 
 - crusta petrosa of, 182, and note. 
 
 ■ cuspid, 179. 
 
 - development of, 183. 
 different stages of, 184. 
 
 ■ distinguished from bones, 177. 
 
 ■ enamel of, 182. 
 
 chemical composition of, 183. 
 
 development of, 186. 
 
 structure of, 183 (note). 
 
 ■ fangs of, 178. 
 ■ formation of, 186. 
 
 Teeth, wisdom, 181. 
 
 uses of, 189. 
 
 two sets of, 189. 
 
 Tela choroidea, 731. 
 
 Temporal arteries. See Arteriei. 
 
 bone, 42. 
 
 fossa, 47. 
 
 nerves. See Nerves. 
 
 Temporo-pditietaX suture, 47. 
 Tendo AchiUis, 283. 
 Tendon of Zinn, 650. 
 
 straight of orbicularis palpebranun, 053 
 
 Tendons of muscles, 193. 
 
 structure of, 299. 
 
 Tensor muscles. See Muscles. 
 Tentorium cerebelU, 684. 
 Testes (of brain), 712. 
 Testicles, 446. 
 
 coverings of, 446. 
 
 excretory duct of, 452. 
 
 proper coat of, 449. 
 
 structure of, 449. 
 
 tubuli of, 450. 
 
 tunica albuginea, 449. 
 
 erythroides, 447. 
 
 propria, 449. 
 
 vaginalis, 447, 
 
 - vessels and nerves of, iSl. 
 
 Testis, coni vasculosi of, 452. 
 mediastinum, 450. 
 rete vasculosum, 451. 
 tubuli, 450. 
 
 Testicular artery, 451. 
 Thalami optic, 742. 
 
 structure of, 744. 
 
 TAt^Abone 93. 
 
 compared with arm bone, lOS. 
 nird cranial nerve. See Nerve. 
 Thoracic arteries. See Arteries. 
 Thorax, aponeuroses of, 300. 
 
 - articulations of, 130. 
 
 - bones of, 64. 
 development of, geikersl, 73. 
 
 - follicles of, 185. 
 (Goodsir). 183 (note). 
 
 - general idea of, 190. 
 
 - incisor, 179 
 
 - ivory of, 183. ~ 
 
 chemical compomtion of, 182. 
 
 development of, 165. 
 
 structure of, 183 (note). 
 
 -milk. See Temporary. 
 ' molar, 180. 
 
 great and small, 180. 
 
 upper and lower compared, 181. 
 
 ■ multi-cuspid, 181. 
 
 ■ nerves of, 181. 
 
 • number of, 177. 
 
 ■ permanent, 177. 
 
 decadence of, 190. 
 
 development of, 190. 
 
 differences of, from temporary, 190. 
 
 eruption of", 189. 
 
 — ■ follicular stage of, 184. 
 
 origin of pulps and sac* of, 164. 
 
 papillary stage of, 184. 
 
 — saccular stage of, 185. 
 
 ■ provisional. See Temporary. 
 
 ■ pulps of, 181. 
 • origin of, 184. 
 
 ■ quadri-cuspid, 181. 
 
 - sacs of, 186. 
 origin of, 184. 
 
 - simple, 183. 
 
 ■ structure, general, 181. 
 — minute, 183. 
 
 ■ supernumerary, 187. 
 tartar of, 183. 
 
 • temporary, 177. 
 
 development of, 183. 
 
 differences of, from permanent, 190. 
 
 ■ eruption of, 183. 
 
 follicular stage of, 180. 
 
 origin of pulps and sacs of, 184. 
 
 papillary stage of, 184. 
 
 saccular stage of, 184. 
 
 shedding of, 188. 
 
 - general description of, 70. 
 
 - mechanism of, 132. 
 
 - movements of, in general, 134. 
 
 one rib of, 132. 
 
 7%yro-arytenoid ligaments. See Chords Yoctiei 
 Thyroid arteries. See Arteries. • 
 
 — — veins. See Veins. 
 
 Tibia, ' 
 
 and ulna, upper parts of, compared, 107. 
 
 radius, lower parts of, compared, 107. 
 
 Tibial arteries. See Arteries, 
 
 nerves. See Nerves. 
 Tissue, adipose, 175. 
 
 bony, 12, 13. 
 
 cartilaginous, 174. 
 
 ceUular, 298. 
 
 elastic, 174. 
 
 fibro-cartilaginoni, 17i. 
 cellular, 298. 
 
 fibrous, 298. 
 ligmmentous, 174. 
 muscular, 198. 
 nervous, 757. 
 tendinous, 289. 
 Toes, articulations of, 174. 
 bones of, 104. 
 phalanges of, 104. 
 Tongue, 332. 
 
 bone of, 333. 
 development of, 336. 
 dorsum of, 332. 
 frsnum of, 333. 
 lymphatics of, 646. 
 median cartilage of, 333. 
 mucous membrane of, 646. 
 muscles of, 333. 
 
 extrinsic, 334. 
 
 intrinsic, 334. 
 
 — nerves of, 646. 
 
 — papills of, 333. 
 
 — rete mucosum of, 646. 
 
 — structure of, 334. 
 
 — uses of, 339. 
 ■ vessels, 339. 
 
 Ton-tils, 333. 
 
 of cerebellum, 718. 
 
 Torcular lIeroi)hili, 5S8. 
 
INDEX. 
 
 TrabecuJa of corpus cavernosum, 455. 
 ————— spleen, 405. 
 Trachea, 416. 
 
 cervical portion, 416. 
 
 glands of, 416. 
 
 structure of, 416. 
 
 thoracic portion, 416. 
 - vessels and nerves, 416. 
 
 Tractus spiralis foraminulentus, 678. 
 Tragic fossa, 668. 
 Tragus, 666. 
 
 ■ - ligament of, 666. 
 Transversahs muscles. See Muscles. 
 Transverse arteries. See Arteries. 
 
 muscles. See Muscles. 
 
 suture, 46, 47. 
 
 veins. See Veins. 
 
 7V«njti«rjo-spinalis muscle. See MuseU. 
 Trapezium, 83. 
 Trapezoid bone, 83. 
 
 ligament, 136. 
 
 Triangulares muscles. See Muscles. 
 Triceps muscles. See Muscles. 
 Trifacial, or trigeminal nerve. See Nerve. 
 Trochanteric cavity, or fossa, 95. 
 Trochanters of femur, 95. 
 
 of humerus, 79. ' 
 
 Trochlea, femoral, 95. 
 
 humeral, 79. 
 
 of orbit, 651. 
 
 Trochlear articulations, characters of, &c., 114. 
 
 nerve. See Nerve, pathetic. 
 
 Trochoid articulations, characters of, &c., 114. 
 Tube, Eustachian. See Eustachian Tube. 
 
 Fallopian, 463. 
 
 T^ber annulare. See Pons Varolii. 
 
 cinereuni, 729. 
 
 Tubercle, ash-coloured, of Rolando, 703. 
 lachrymal, 645. 
 
 laminated, 717. 
 
 of Lower, 488. 
 
 Tidtercles of Santorini, in larynx, 424. 
 
 in nose, 640. 
 
 Tuberrula quadrigemina, or bigemina, 712, 
 
 structure of, 714. 
 
 T\iberosities, calcaneal, 102. 
 
 of femur, 95. 
 
 of humerus, 79. 
 
 ■ of tibia, 97. 
 
 Tuberositi/, bicipital, 81. 
 
 of ischium, 89. 
 
 maxillary, 51. 
 
 Tubes of Bellini, 437. 
 
 TViu/t of intestine. See Intestine. 
 
 recti, of kidney, 437. 
 
 of testicle, 452. 
 
 seminiferi, 452. 
 
 ' of stomach, 361. 
 
 ' uriniferi, convoluted, 437. 
 
 straight, 437. 
 
 T\ibulus centralis modioli, 679. 
 Ttmica adnata, 648. 
 
 albuginea testis, 449. 
 
 conjunctiva, 648. 
 
 erythroides, 448. 
 
 propria testis, 449. 
 
 Ruyschiana, 657. 
 
 sclerotica, 654. 
 
 vaginalis testis, 448. 
 
 vasculosa testis, 449 (note). 
 
 Tunics of eye. See Eye. 
 Turbinated bone, inferior, 56. 
 
 - middle, 41, 
 
 superior, or ethmoidal, 41. 
 
 ' sphenoidal, 38. 
 
 Ti/mpanic bone, circle, or ring, 45 
 T)/mpanum, bones in, 674. 
 
 circumference of, 672. 
 
 lining membrane of, 670. 
 
 membrane of, 675. 
 
 secondary, 671. 
 
 • orifice of, cochlear, 671. 
 vestibular, 670. 
 
 — recess of, 672. 
 
 — wall of, external, 669. 
 internal, 670. 
 
 Ulna, 79. 
 
 and tibia, upper parts of, compared, 107, 
 
 Vmbilicus, 308. 
 
 Unciform bone, 83. 
 
 eminence, 730. 
 
 Unguis, 730. 
 Urachus, 443. 
 Ureter, 440. 
 
 structure of, 441. 
 
 orifices of, 444. 
 
 muscles of, 445. 
 
 valve of, 444. 
 
 Urethra, female, 469, 
 
 muscles of, 470, 
 
 male, 457. 
 
 bulb of, 459. 
 
 dilatations, or sinuses, 459. 
 
 internal surface, 459. 
 
 lacunee, 460. 
 
 membranous portion, 459. 
 
 muscles of, 457. 
 
 prostatic portion of, 457. 
 
 spongy portion of, 459. 
 
 structure of, 460. 
 
 Urinary apparatus, 435, 
 
 Uterine veins, 467. 
 
 Uterus, 464. 
 
 cavity and mouth of, 465, 
 cervix or neck of, 465, 
 coat, mucous, 467, 
 - serous, 467, 
 
 • development, 468. 
 
 ■ follicles of, 466. 
 
 • functions of, 468. 
 
 ■ fundus of, 466. 
 
 • glands, tubular, of, 468 (note). 
 
 ■ gravid, fibres of, 467. 
 sinuses of, 467. 
 
 - vessels and nerves of, 464. 
 
 ■ ligaments of, broad, 466. 
 round, 466. 
 
 • nerves of, 468. 
 
 • structure of, 466. 
 vessels of, 468. 
 
 Utriculus vestibuli, 681. 
 Uvea, 670. 
 Uvula, 332. 
 
 vesicae, 459. 
 
 cerebelli, 715 (note). 
 
 Vagina, 468. 
 
 bulb of, 469. 
 
 — columns and rugse of, 468. 
 
 — development of, 469. 
 
 — mucous membrane of, 469. 
 
 — muscles of, 469. 
 structure of, 468. 
 
 Vaginal process of temporal bone, 44. 
 Valve of Bauhin, 372. 
 
 • Eustachian, 486. 
 
 • ileo-ccecal, 372. 
 colic, 372, 
 
 ■ mitral, 484, 
 
 ■ pyloric, 352, 
 
 ■ of Thebesius, 486. 
 
 ■ tricuspid, 484. 
 
 ■ of Vieussens, 711. 
 ' columella of, 71S. 
 
 Valves of Kerkringius, 365. 
 
 of heart. See Heart. 
 
 of intestines. See Intestine 
 
 of lymphatics, 617. 
 
 semilunar, or sigmoid, 464. 
 
 of Tarin, 720. 
 
 of veins, 575. 
 Valvula conniventes, 365. 
 Vas aberrans, 452. 
 deferens, 452. 
 
 structure, 452. 
 
 Vasa afferentia, lymphatic, 614. 
 brevia, arterial, 509. 
 venous, 599. 
 
 ■ efferentia of epididymis, 451. 
 • lymphatic, 614, 
 
 ' sudatoria, 634. 
 • vasorum of arteries, 520, 
 of veins, 576, 
 
 — vorticosa, 587. 665. 
 Veins, in general, 573, 
 
 — anastomoses of, 574, 
 branches of, 575. 
 
 — coats of, 576. 
 
 — course of, 574. 
 
INDEX. 
 
 905 
 
 Veins, deep, 574. 
 
 method of description of, 577. 
 
 nerves of, 576. 
 
 ^^— origin of, 574. 
 
 plexuses of, 574. 
 
 preparation of, 576. 
 
 relations of, with arteriei, 575. 
 
 satellite, 574. 
 
 sinuses of, 575. 
 
 structure of, 576. 
 
 sub-cutaneous, 574. 
 
 superficial, 574. 
 
 termination of, 575. 
 
 valves of, 575. 
 
 varieties of, 575. 
 
 vasa vasorum of, 575. 
 
 vessels of, 575. 
 
 in particular, 577. 
 
 abdominal sub-cutaneoiu, 604. 
 
 of ala of nose, 588. 
 
 alveolar, 589. 
 
 angular, 588. 
 
 of the arm, superficial, 594. 
 
 articular, of knee, 603. 
 
 ascending cervical, 580. 
 
 lumbar, 606. 
 
 auricular anterior, 590. 
 
 posterior, 590. 
 
 axillary, 593. 
 
 azygos, general remarks on, 60) 
 
 great, 605. 
 
 lesser, 606. 
 
 lumbar, 607. 
 
 ■ basilic, 595. 
 
 ■ brachial, 597. 
 
 • brachio-cephalic, left and right, *; * 
 
 ■ bronchial, left, 420. 
 right, 420, 606. 
 
 - distribution of, 421. 
 
 ' buccal, 589. 
 
 ■ calcaneal, internal, 604. 
 
 ■ capsular, inferior and middle, 591 
 
 ■ cardiac, great, 578. 
 small, 578. 
 
 cava, ascending or inferior, 596. 
 
 descending or superior, 51H 
 
 cephalic, 595. 
 
 ■ of thumb, 594. 
 
 • cerebral, inferior, anterior, 587. 
 
 lateral, 584. 
 
 ' median, 586. 
 
 internal, 585. 
 superior, 585. 
 
 ■ median, SSC 
 
 ■ cerebellar, anterior lateral, 58* 
 inferior lateral, 5Sa 
 
 ' cervical, ascending, 580. 
 deep, 580. 
 
 ■ choroid, 586. 
 
 of eye, 658. 
 
 • ciliary, 587. 
 
 ' circumflex, brachial, 598. 
 
 femoral, 603. 
 
 • iliac, 603. 
 
 ' colic, left and right, 599. 
 
 ■ coronary of the heart, anterior, 578. 
 
 great, 578. 
 
 lips, inferior, 589. 
 
 — superior, 589. 
 
 stomach, 362. 
 
 • of the corpus cavemosum, 601. 
 striatum. 586. 
 
 deep cervical, 580. 
 
 — femoral, 603. 
 
 • dental, anterior, 589 
 
 inferior, 590. 
 
 superior, 589 
 
 ■ diaphragmatic, 601. 
 
 ' diploic, 585, 591. 
 
 • dorsal of the foot, deep, 602. 
 external, 603. 
 
 internal, 603. 
 
 ' nose, 588. 
 - penis, 601. 
 
 ' dorsi-spinal, 608. 
 
 ■ of the dura mater, 583. 
 
 ■ at the elbow, 595. 
 • emulgent, 598. 
 
 ■ epigastric, deep, 603. 
 superficial, 60S 
 
 Veins, facial, 588. 
 
 posterior, 589, 
 
 of the falx cerebri, 586. 
 
 • femoral, 603. 
 deep, 603. 
 
 • frontal, 587. 
 
 ■ of Galen in brain, 584. 
 ■ heart, 577. 
 
 • gastro-epiploic, 361. 
 ■ gluteal, 601. 
 
 • of hand, superficial, 594. 
 
 • hemorrhoidal, inferior, 601. 
 ' middle, 601. 
 
 --superior, 601. 
 
 — head, general remarks on, 592. 
 
 — hepatic, 600. 
 
 in the liver, 391, 398. 
 
 — hypo-gastric, 601. 
 
 — iliac, common, 600. 
 
 eriemal, 603. 
 
 internal, 601. 
 
 — ilio-lumbar, 607. 
 
 — infra-orbital, 589. 
 
 — innominate of Meckel, 579. 
 ■ of Vieussens, 578. 
 
 ■ inter-costal, 607. 
 
 superior, left, 606. 
 
 right, 606. 
 
 lobular, of liver, 391 (note). 
 
 — of intestines, 599. 
 
 — intra-lobular, of liver, 393 (note). 
 
 spinal, 609. 
 
 anterior, longitudinal, 609. 
 
 ■ transverse, 609. 
 
 - lateral, 610. 
 
 — posterior, longitudinal, 610. 
 • transverse, 610. 
 
 ■jugular, 581. 
 
 anterior, 582. 
 
 external, 581. 
 
 compared with cranial, 610. 
 
 — internal, or deep, 583. 
 posterior, 607. 
 
 • laryngeal, inferior, 580. 
 — superior, 582. 
 
 ' lingual, 590. 
 
 ' longitudinal of scull, inferior, 586. 
 
 spine. See Intraspinal. 
 
 ■ of lower extremity, deep, 602. 
 
 superficial, 603. 
 
 lumbar, or vertebro-lumbar, 5'17. 
 
 ascending, 606. 
 
 azygos, 607. 
 
 ' mammary, internal, 580. 
 masseteric, anterior, 589. 
 • posterior, 590. 
 
 ' mastoid, 584, 590. 
 ■ maxillary, external, 588. 
 ' intornal, 589. 
 
 — median of the fom, 595. 
 
 basilic, 595. 
 
 cephalic, 595. 
 
 — mediastinal, 580, 60C. 
 
 — medullary, 610. 
 
 — meningeal, 591. 
 ■ middle, 590. 
 
 ■ mesaraic, 599. 
 ' mesenteric, inferior or smaL, &(*^ 
 superior or gre. t, 59^ 
 
 ' nasal, 588. 
 
 • obturator, 601. 
 
 ■ occipital, deep, 590. 
 
 superficial, 589. 
 
 ■ (esophageal, 606. 
 
 ■ omphalo-mesenteric, 599. 
 
 ■ ophthalmic, 587. 
 
 ■ orbital, external, 589. 
 
 ■ ovarian, 598. 
 
 • palatine, inferior, 589. 
 su-perior, 589. 
 
 palmar, 593. 
 ' palpebral, external, 589. 
 ' inferior, 588. 
 
 • pancreatic, 402. 
 
 • parotid, 590. 
 
 • of particular organs or tissues. 
 
 gans or tissues. 
 
 • of pelvis, in female, 602. 
 male, 601. 
 
 of penis, 601. 
 
 5Y 
 
906 
 
 INDEX. 
 
 Veins, pericardiac, 580. 
 
 peroneal, 602. 
 
 pharyngeal, 591. 
 
 phrenic, inferior, 598. 
 
 . superior, 580. 
 
 plantar, 602. 
 
 popliteal, 602. 
 
 portal, or vena porta, 597, 599. 
 
 branches of origin of, 598. 
 
 in the liver, 390. 
 
 ■ sinus of, 599. 
 
 profunda cervicis, 580. 
 femoris, 603. 
 
 — pterygoid, 590. 
 
 — pudic, external, 604. 
 internal, 601. 
 
 — pulmonary, 577. 
 ' distribution of, 421. 
 
 ■ rachidian. See Spinal. 
 
 ■ radial cutaneous, 595. 
 deep, 594. 
 
 • ranine, 590. 
 
 ■ renal, 597. 
 
 ' sacral, lateral, 607. 
 middle, 607. 
 
 ' salvatella, 594. 
 ' of Santorini, 585. 
 ' saphenous, external, 605. 
 ' internal, 603. 
 
 ' second, 604. 
 
 ' satellite, of lingual nerve, 590. 
 ■ scapular, superior, 582. 
 posterior, 582. 
 
 ^— sciatic, 601. 
 
 scrotal, 601. 
 
 semi-azygos, 606. 
 
 short, of stomach, 599. 
 
 spermatic, left and right, 598. 
 
 spheno-palatine, 589, 591. 
 
 spinal, 605. 
 
 '— deep. See Intraspinal. 
 
 general remarks on, 611. 
 
 posterior, deep. See Inira^spinal. 
 
 ■ superficial, 608. 
 
 ■ superficial, 60S. 
 
 in neck, 608. 
 
 — posterior, 608. 
 
 ■ of spinal cord, 610. 
 • splenic, 599. 
 
 ■ distribution of, 406. 
 
 ■ stylo-mastoid, 590. 
 
 sub-clavian, left and right, 593. 
 mental, 589. 
 
 supra-orbital, 588. 
 
 renal, inferior and middle, 598 
 
 scapular, 581. 
 
 sural, 603. 
 
 temporal, 589. 
 
 deep, 590. 
 
 middle, 589. 
 
 • superficial, 589. 
 
 • temporo-maxillary, 589. 
 ■ofThebesius, 578. 
 
 • thymic, 580. 
 
 • thyroid, inferior, 580. 
 
 middle, 591. 
 
 superior, 591. 
 
 • tibial, anterior, 602. 
 -posterior, 602. 
 
 tibio-peroneal, 602. 
 tonsillar, 333. 
 transverse, cervical, 582. 
 
 facial, 590. 
 
 humeral, 582. 
 
 ■ ulnar cutaneous, anterior, 595. 
 — posterior, 595. 
 
 ■ deep, 592. 
 
 • umbilical, 600. 
 
 ■ of upper extremity, deep, 592. 
 superficial, 593. 
 
 • uterine, 467, 601, 602. 
 
 ■ vaginal, 602. 
 
 • vasa brevia, 599. 
 vorticosa, 587. 
 
 ■ ventricular, cerebral, 586. 
 
 ■ of vertebra, 610. 
 
 ■ vertebral, 581. 
 
 • vertebro-costal, inferior, 606. 
 
 superior, left, 606. 
 
 — i right, 605 
 
 Veins, vertebro-lumbar, 607. 
 
 vesical, female, 602. 
 
 male, 601. 
 
 vidian, 589. 
 
 Velum interpositum, 731, 740. 
 
 meduUare, anterior, 713. 
 
 posterior, 718 (note). 
 
 palati, 331. See Palate, soft. 
 
 pendulum palati, 331. 
 
 Vena cava inferior, or ascending, 596. 
 superior, or descending, 578. 
 
 Venm comites, 572, 
 
 minimse, 508. 
 
 Venous plexuses. See Plexuses. 
 
 system generally, 572. 
 
 Venter ilii, or internal iliac fossa, 88. 
 Ventricle of Arautius, 704. 
 
 of corpus callosum, 737. 
 
 fifth, 738. 
 
 fourth, 718. 
 
 choroid plexuses of, 720. 
 
 — fibrous layers of, 719. 
 -- fossette of, 704. 
 
 ■ laminated tubercle of, 717 
 • orifice, inferior, 719. 
 
 ■ semilunar fold of, 719. 
 valves of base of, 719. 
 
 ■ of larynx, 424. 
 
 ■ lateral, 744. 
 
 body of, 744. 
 
 comu anterior, 744. 
 
 descending, 744. 
 
 posterior, 744. 
 
 ■ of septum lucidum, 738. 
 •third, 729, 741. 
 
 choroid plexuses of, 741. 
 
 commissure of, anterior, 742. 
 
 posterior, 742. 
 
 - soft or gray, 729, 741. 
 
 ■ floor of, anterior part of, 729. 
 
 middle and posterior part of, 
 
 729. 
 • openings of, 742. 
 
 Ventricles, cerebral, fluid of, 744. 
 
 lining membrane of, 747. 
 
 Gall's views regarding, 750. 
 
 — — of heart. See Heart. 
 
 of spinal cord, 701. 
 
 Ventriculus, 352. 
 
 succenturiatus, 362. 
 
 Vermiform appendix, 373. 
 
 process, inferior, 716. 
 
 superior, 716, 
 
 Vertebra, cervical, first, 23. 
 
 second, 24. 
 
 seventh, 25. 
 
 dentata, 24. 
 
 dorsal, first, 25. 
 
 eleventh and twelfth, 85. 
 
 general description of, 19. 
 
 lumbar, fifth, 26. 
 
 prominens, 25. 
 
 Vertebra, articular processes of, in different regiou, S8» 
 
 articulations of. See Articulatiom. 
 
 bodies of, in different regions, 20. 
 
 cervical, 19. 
 
 • characters of, general, 19. 
 
 distinctive, 20. 
 proper, 22. 
 
 — coccygeal, 19. 
 
 — development of, 31. 
 
 — dorsal, 19. 
 
 — false, 19. 
 
 — foramen of, in different regions, 19. 
 
 — internal structure of, 31. 
 
 — laminse of, in different regions, 20. 
 
 — ligaments of. See Ligaments. 
 
 — lumbar, 19. 
 
 — notches of, in different regions, 80. 
 -- number of, 19, 
 
 — sacral, 19, 
 
 -► sacro-coccygeal, 26. 
 
 union of, 32. 
 
 spinous processes of, in different regions, SS, 
 
 transverse processes of, in diflferent region*, 
 
 23. 
 ■true, 19. 
 
 Vertebral canal, 30. 
 
 column, 19. 
 
 articulations of, 115-123. 
 
INDEX. 
 
 90*2 
 
 Vertebral column, curvatuiea of, 28. 
 
 deTelopment of, 32. 
 
 ' dimensions of, 28. 
 
 figure and aspects of, 29. 
 
 ' moTements of entire, 121-123. 
 
 grooves, 20. 
 ligaments. 
 
 See Ligaments. 
 See Veins. 
 
 Vertebro-costaX veins. 
 Yerumontanum, 461. 
 Vesica fellea, 394. 
 
 urinaria, 440. 
 
 Vesicles, Graafian, 461. 
 Vesicula seminales, 453. 
 
 efferent duct of, 454. 
 
 structure, 454. 
 
 Vestibule of ear, 676. 
 
 aqueduct of, 676. 
 
 calcareous matter of, 681. 
 
 crista of, 676. 
 
 ■ fovea and recessus sulcifonnis, 676. 
 
 membranous, 680. 
 
 openings into, 676. 
 
 sacculus of, 680. 
 
 — ; sinus, common, or utricle of, 680. 
 
 Visceral nerves. See iferves. 
 Vitreous table of cranial bones, 35. 
 
 Vocal cords, 426. 
 Vomer, 57. 
 Vulva, 470. 
 
 development of, 471. 
 
 fourchette, 470. 
 
 mucous membrane, 471. 
 
 parts of, 470. 
 
 Wings of sphenoid bone, lesser, 37. 
 great, 38. 
 
 Ingrassius, 37 
 
 Womb. See Uterus. 
 Wormian bones, 50. 
 Wrist. See Carpus. 
 
 Xiphoid cartilage, or appendix, 65. 
 
 Zinn, zone of, 655. 
 Zonula Zinni, 655. 
 Zygoma, 61. 
 Zygomatic arch, 61. 
 
 bone, 54. 
 
 canal, 55. 
 
 - fossa, 61. 
 
 - process of temporal bone, 42. 
 malar bone, 55. 
 
 THE END. 
 
THE LIBRARY 
 
 UNIVERSITY OF CALIFORNIA 
 
 San Francisco Medical Center 
 
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