NATIONAL LIBRARY OF MEDICINE Washington Founded 1836 U. S. Department of Health, Education, and Welfare Public Health Service THE ANATOMY OF THE HUMAN BODY. IN FOUR VOLUMES, ILLUSTRATED WITH ONE HUNDRED AND TWENTY-FIVE ENGRAVINGS* VOLUME I. CONTAINING THE ANATOMY OF THE BONES, MUSCLES, AND JOINTS. FROM THE FOURTH LONDON EDITION, IMPROVED B.Y THE AUTHOR. NEW-YORK: PRINTED AND SOLD BY COLLINS AND PERKINS, NO. 189, PEARL-STREET. 1809. TO ALEXANDER WOOD, SURGEON, WHOSE ABILITIES, AND SKILL, AND DISINTERESTED CONDUCT, HAVE RAISED HIM, BY COMMON CONSENT, TO THE FIRST RANK, IN A MOST USEFUL PROFESSION, CONDUCTING HIM, IN HONOUR, TO THAT PERIOD OF LIFE IN WHICH HE MUST FEEL, WITH PLEASURE, HOW COMPLETELY HE ENJOYS THE CONFIDENCE OF THE PUBLIC, AND THE ESTEEM OF ALL GOOD MEN, THIS BOOK OF ANATOMY IS PRESENTED BY HIS PUPIL JOHN BELL. ADVERTISEMENT, By the American Publishers. IN offering, for the patronage of the Medical Profes- sion, an American edition of this work, the publish- ers have merely to state, that they have been led to the undertaking in consequence of the repeated solici- tations of some of the most eminent Anatomists m the United States, who have authorized them to represent it as the " most complete system of Anatomy, which embraces a portion of Physiology, in the English lan- guage." The unparalleled sale it has experienced in Great Britain, having within a short period passed in- to four editions, is a striking evidence of its great popularity in the Medical schools of that kingdom. When we consider the bold, and often uncourteous language of John Bell towards many eminent wri- ters, even his cotemporaries, sometimes himself per- haps falling into a mistake, an event which would not fail to expose him to powerful attacks in return, it is evident that his work must possess extraordinary at- tractions, to have arisen, amidst such impediments, to its present eminence. A few of the numerous commendations bestowed on the work by the most respectable critics, are ad Vol. I. a IV duced below. Many more might have been added, but it is presumed that these are sufficient to satisfy every reasonable enquirer. In regard to the advantages claimed by this Ameri- can edition, the publishers believe that they have on no former occasion been more successful in accom- plishing the two important objects—greater typogra- phical correctness than the original, and great reduc- tion in the price of the work. W^ith respect to the former of these advantages, the publishers can confidently claim a decided prefer- ence. Seldom has a work been issued from the press more loaded with typographical errours, many of them of serious magnitude, than the different editions of this work, which have been published in London. Partly through the aid of a very competent medical friend, who generously offered his services to settle their nu- merous queries, the publishers have been able to de- tect and correct several hundred errours of the press. The custom of some authors in Great Britain, of sub- mitting their manuscripts, not always very legible, en- tirely to the care of the printer, whose distance from their own place of residence precludes the possibility of their examining the proof-sheets, is the general, though inadequate apology, offered for the numerous typographical mistakes, which characterize many va- luable works imported from England. V In regard to cheapness, the price of this edition is less than half that of the London copy, as sold in this country. The Engravings also, it is believed, will not disgrace American Artists. The major part of those executed on copper, especially the engravings in the second volume, are much superior to the origi- nal ; and those on wood, introduced on the printed pages, are pronounced by competent judges, to an- swer the object in view better than the faint and ob- scure impressions of the English copy. The artists who have produced these engravings, having both been regularly taught the Anatomy of the Human Body, may reasonably claim a reliance on their accuracy. It will be scarcely necessary to remark, that scrupu- lous care has been taken, not to omit a syllable of the letter-press nor a plate, but that the work should be presented entire. It will be apparent to the Medical Profession, that in the execution of this work, the publishers have in- curred a very heavy expense. If they shall find them- selves encouraged in this instance, and in their edition of Professor Smith's Abridgment of John Bell's Principles of Surgery, now in the press, as they have been in several of their late offerings to the profes VI sion*, they intend to pursue, with redoubled exertions, the business of reprinting, at greatly reduced prices, the best works of English Authors relating to the sci- ence of Medicine : and they enjoy the reflection, that, besides receiving an equitable pecuniary remuneration, they shall materially subserve the interests of Me- dical Science in the United States. CHARACTER OF THIS WORK, By Professional Critics. « It would be injustice to confound this work with the ordinary compilations from the common stock of elementary writers, and the * The following works have been lately published, either entirely by COLLINS & PERKINS, or conjointly with other booksellers : HENRY's CHEMISTRY, in octavo, from the fourth London edition, with Notes by professor Silliman, price three dollars. Burns's three, volumes on the Anatomy of the Gravid Uterus, on Uterine Hemorrhage, and on Abortion. The English edition sells at six dollars. The price of the American copy, in one handsome volume, octavo, and much more correctly printed, is two dollars. Hamilton on Purgative Medicines, from the second English edi- tion, with the Formulae, translated by Dr. James, of Philadelphia, price one dollar and twenty-five cents. The English edition sells at three dollars and fifty cents. Wilson's Treatise on Febrile Diseases. The English edition, in five volumes, octavo, including the Essay on the Nature of Fever, sells at sixteen dollars. The price of the American copy, in two volumes, octavo, is six dollars ; and on fine paper, calf gilt, eight dollars. Besides the above re-publications, C. & P. have printed the fol- lowing original works : Bard's Compendium of Midwifery, with nineteen engravings, in duodecimo, price one dollar and twenty-five cents. Skaman's Dissertation on the Waters of Saratoga and Ballston, \»iih a Map of the surrounding country, in duodecimo, price seventy five cents. vu transcribed lectures of the class-room. It is obviously the result of very extensive study, both in books, and in the dissecting-room, and its completion now supplies a warft which was much felt by the En- glish reader. The description is clear and accurate, and the en- graved sketches occasionally introduced, are also very happily de- vised in assisting the reader to gain a full idea of the relative situa- tion of important and complicated parts of anatomy. They add much to its sterling value, as a comprehensive and well executed system." Aikin's Annual Review. " Anatomy, in common with every other branch of natural sci- ence, has been going on with progressive improvement ever since the arrival of letters in Europe. It therefore becomes necessary, from time to time, that new systems should be formed, in which the essays of different professors who have exerted themselves in perfecting the deacrTjrtron tj£ particular pai la of tire body, or in meli- orating the whole, should be collected." After enumerating many celebrated anatomists who have improved the art, the reviewers con. elude : " Having said thus much with regard to the great men who have laboured and are labouring to improve the art which it seemed to demand, we shall readily acknowledge that the authors have col- lected their materials with industry, and have enriched their work with the principal improvements in physiology, which the present age has produced." British Critic. " In our account of the former part [the first two volumes by John Bell,] we bore a willing testimony to the ingenious and interesting manner in which the subject was handled. By judiciously blending the physiology, or doctrine of functions, with the anatomical de- scriptions, by frequent occasional references to pathology and prac- tice, and by a manner peculiarly impressive and interesting, he was enabled to excite the attention of the student to a subject of the first importance to the healing art, but one which is rendered dry and disgusting by the ordinary mode of treating it. The latter volumes by Mr. Charles Bell, are respectably executed ; and together they form a body of anatomy greatly superior to any at present to be found in our language." London Medical and Chirurgical Review. The editors of the New- York Medical Repository, announce the present undertaking thus : " Our readers we are confident will universally participate the VH1 pleasure we feel in announcing that Messrs. Collins & Perkins have undertaken to give an American edition of the ANATOMY OF THE HUMAN BODY, by John and Charles Bell, in two large volumes, octavo, from the fourth London edition, in four rolumes, octavo, corrected, and illustrated by one hundred and twenty five engravings. This grand work, embracing by far the most complete system of Anatomy and Physiology in the English language, and possessing a reputation which is extended by the ap- probation of every additional circle of readers, will thus be published at a price so greatly reduced as to circulate to a wide extent, be a- dopted as a standard authority in our Medical Seminaries, and even- tually come into the hands of all practitioners of physic in the United States. We most sincerely congratulate the public on the prospect of acquiring this splendid improvement in the means of cultivating Anatomy and Physiology in c»u; yrai l of uui country , as wc are confident that the general circulation of this work would be alone sufficient to advance, in a considerable degree, the respectability and usefulness of the Medical profession in this new world." The editors of the New- York Medical and Philoso- phical Journal and Review, in announcing the same undertaking, dwell on the great importance to the pro- fession of thus reducing the prices of imported books, and proceed as follows : " It has been objected to the editions issued from our presses, particularly those in which there are plates, that though cheaper, they are likewise inferior to those imported. This we think will not be the case with the above edition of Bell's Anatomy ; for we have seen some of the plates, which are superior to those in the London copy. The extensive sale of the book, will, we hope, re- munerate the activity and enterprize of the publishers." The editor of the Philadelphia Medical Museum, has called the attention of his readers to the same subject, and informed them, that " This highly useful and important work is to be printed in two volumes, Svo. on a fine vellum paper, from the fourth London edi IX tion. A selection of reviews from English publications accompanies the prospectus, which cannot fail of evincing the high degree of estimation in which this interesting work is held ; and as it is given at less than half the price of the English edition, must ensure the sanction of the Physicians of America, as a work in the highest de- gree worthy of a place in every medical library." -----•<£>«■—---- MEDICAL BOOKS. COLLINS &? PERKINS announce to the Medical Profession, that they have been induced to turn their attention to the sale of MEDICAL, CHEMieAt, ANI> BOTANICAL BOOKS, In consequence of the solicitations of many of the most respectable of the Faculty. Whilst they respectfully solicit the further patro- nage of the Profession at large, the advertisers should, with gratitude, acknowledge the very extensive en- couragement which they have already received. Their obligations are due, not only to the different medical professors and lecturers of the two Colleges in New- York, who in their private capacity, have recommend- ed their establishment, but also to medical institutions? which have promoted their undertaking, by officially constituting the advertisers their printers and medical booksellers. Their medical catalogue, which already contains more than double the number of medical books to be found in any book-store of the United States, will be constantly enlarged by the addition of every new work of merit which may appear either in Europe or Ameri- ca ; the advertisers having established a correspondence X in England, which will insure to them this important advantage, unless political differences between the two countries may operate to defeat it. The several Medical Journals printed in Philadelphia and Baltimore, are also regularly received for delivery to subscribers and others. With regard to charges, those for American books, must be regulated by the prices adopted by their pub- lishers ; but foreign books are priced by the importer. To those of the Faculty who have already dealt with the advertisers, it may be sufficient to observe, that they pledge themselves to continue, to sell on the same favourable terms as heretofore. That every satisfac- tion, however, may be given on this head, their invoices consisting of the sterling cost, shall, as heretofore, be cheerfully offered for the inspection of their customers. Upon American editions, (periodical publications and a few others excepted) liberal discounts will be allow- ed to wholesale purchasers ; but upon imported books, such are their present reduced retail prices, only a very small discount can be afforded. Did the adver- tisers adopt the practice of marking imported books as much above their cost as are those of American origin, the same large discounts could with equal propriety be allowed ; but they apprehend that such a system is not calculated to dispense equal justice to all, nor to ena- ble the purchaser of a single book to possess himself of it at a price for which it can be fairly afforded. PREFACE, X O those who are at all acquainted with books on anatomy, the appearance of a new one on the subject will not be sur- prising : to those who are not yet acquainted with such writ- ings, I have only to say that I have written this book, because I believed that such a one was needed, and must be useful. I have endeavoured to make it so plain and simple as to be easily understood; I have avoided the tedious interlarding of techni- cal terms (which has been too long the pride of anatomists and the disgrace of their science), so that it may read smoothly, compared with the studied harshness, and, I may say, ob- scurity, of anatomical description. If an author may ever be allowed to compare his book with others, it must be in the me- chanical part; and I may venture to say, that this book is full and correct in the anatomy, free and general in the explana- tions, not redundant, I hope, and yet not too brief. If, in the course of this volume, I shall appear to have given to theories a place and importance far higher than they really deserve, my reader will naturally feel how useful they are in preserving the due balance between what is amusing and what is useful; between the looser doctrines of functions and the close demonstration of parts. He will be sensible how much more easily these things can be read in the closet than taught in any public course ; he will, I think, be readv to b vi? PREFACE. acknowledge, that I introduce such theories only as should connect the whole, and may be fairly distinguished as the phy- siology of facts ; and he will perceive, that in this, too, I feel a deference for the public opinion, and that respect for the established course of education which it is natural to feel and to comply with. Thus, perhaps, it is less immodest for an author to put down what he thinks he may honestly say concerning his own book, than to omit those^apologies which custom requires ; which give assurance that he has not entered upon his task rashly, nor performed it without some labour and thought; which are the truest signs of his respect for the Public, and of his care for that science to which he has devoted his life. With these intentions and hopes I offer this hook to the Public; and more particularly to those in whose education I have a chief concern : not without a degree of satisfaction at having accomplished what, I think, cannot fail to be useful; and surely not without an apprehension of not having done (in this wide and difficult subject) all that may be expected or wished for. Every book of this kind should form a part of some greater system of education : it should not only be entire in its own plan, but should be as a part of some greater whole ; without which support and connection a book of science is insulated and lost. This relation and subserviency of his own particu- lar task to some greater whole, is first in an author's mind: lie ventures to look forward to its connection with the general science and common course of education ; or he turns it to a correspondence and harmony with his own notions of study : and if these notions are to give the complexion and character to any book^ it should be when it is designed for those who are entering upon their studies, as yet uncertain where to begin, or how to proceed. Hardly any one has been so fortunate as to pursue the study of his own science under any regular and perfect plan j and there are veiy few with whom a consciousness of this does not make a deep and serious impression at some future period, ac- PREFACE. yjj companied with severe regret for the loss of time never to be retrieved. In medicine, perhaps, more than in any other science, we begin our studies thoughtless and undecided, fol- lowing whatever is delightful (as much is delightful), and ne- glecting the more severe and useful parts : but as we advance towards that period in which we are to enter upon a most dif- ficult profession, and to take our place and station in life ; and when we think of the hesitation, anxiety, and apprehension, with which we must move through the first years of practice__ we begin to look back with regret on every moment that is past ; with a consciousness of some idle hours ; and (what is more afflicting still) with an unavailing sense of much ill- directed, unprofitable labour:—for there is no study upon which a young man enters with a. more eager curiosity ; but not instructed in what is really useful, nor seriously impressed with the importance of his future profession, he thinks of his studies rather as the amusement, than as the business, of life; slumbers through his more laborious and useful tasks, and soon falls off to the vain pursuit of theories and doctrines. If I were not persuaded of the important consequences, of the infinite gain or loss which must attend the first steps, in every profession, I should not feel, but, above all, I should not venture to express, an anxiety, which may be thought affected by those who cannot know how sincere it must be ; for, in our profession, this is the course of thmgs, that a young man, who, by his limited fortune, or the will of his friends, by absence from his native country, or by the destina- tion of his future life, is restricted to a few years of irregular, capricious, ill-directed study, throws himself at once into the practice of a profession, in which, according to his ignorance or skill, he must do much good or much harm. Here there is no time for his excursions into that region of airy and fleeting visions, and for his returning again to sedate and useful labour: there is no time for his discovering, by the natural force of his own reason, how vain all speculations are.—In but a few vears, at most, his education is determined ; the limited term is completed ere he have learnt that most useful of all lessons, viii PREFACE. the true plan of study; and his opportunities come to be valued (like every other happiness), only when they are lost and gone. Of all the lessons which a young man entering upon our pro- fession needs to learn, this is, perhaps, the first,—that nfi should resist the fascinations of doctrines and hypotheses, till he have won the privilege of such studies by honest labour, and a faithful pursuit of real and useful knowledge. Of this knowledge, anatomy surely forms the greatest share.—Anato- my, even while it is neglected, is universally acknowledged to be the very basis of all medical skill—It is by anatomy that the physician guesses at the seat, or causes, or consequences, of any internal disease.—Without anatomy, the surgeon could not move one step in his great operations ; and those theories could not even he conceived, which so often usurp the place of that very science, from which they should flow as probabilities and conjectures only, drawn from its store of facts. A consciousness of the high value of anatomical knowledge never entirely leaves the mind of the student. He begins with a strong conviction that this is the great study, and with an ardent desire to master all its difficulties : if he relaxes in the pursuit, it is from the difficulties of the task, and the se-' duction of theories too little dependent on anatomy, and too easily accessible without its help. His desire for real know- ledge revives only when the opportunity is lost; when he is to leave the schools of medicine'; when he is to give an account of his studies with an anxious and oppressed* mind, conscious of his ignorance in that branch which is to be received as the chief test of his professional skill ; or when, perhaps, he feels a more serious and manly impression, the difficulty and im- portance of that art which he is called to practise. Yet, in spite of feeling and reason, the student encourages in himself a taste for speculations and theories, the idle amuse- ments of the day, which, even in his own short course of study, he may observe sinking in quick succession into neglect and oblivion, never to revive ; he aspires to the character of a physiologist, to which want of experience, and a \-outhfuj PREFACE. ix fancy, have assigned a rank and importance which it does not hold in the estimation of those who should best know its weak- ness or strength. The rawest student, proud of his physiolo- gical knowledge, boasts of a science and a name which is modestly disclaimed by the first anatomist, and the truest phy- siologist of this or any age. Dr. Hunter speaks thus of his physiology, and of his anatomical demonstration: " Physio- " logy, as far as it is known, or has been explained by Haller, " and the best of the moderns, may be easily acquired by a " student without a master, provided the student is acquainted " with philosophy and chemistry, and is an expert and ready " anatomist; for with these qualifications he can read any " physiological book, and understand it as fast as he reads. " In this age, when so much has been printed upon the sub- " ject, there is almost as little inducement to attend lectures " upon physiology, as there would be for gentlemen to attend " lectures upon government, or upon the history of England. u Lectures upon subjects which are perfectly intelligible in " print, cannot be of much use, except when given by some " man of great abilities, who has laboured the subject, and " who has made considerable improvements either in matter or " in arrangement. " In our branch, those teachers who take but little pains to " demonstrate the parts of the body with precision and clear- " ness, but study to captivate young minds with ingenious " speculation, will not leave a reputation that will outlive them " half a century. " I always have studied, and shall continue my endeavours, " to employ the time that is given up to anatomical studies as " usefully to the students as I can possibly make it—and there- " fore shall never aim at showing what I know, but labour to " show and describe, as clearly as possible, what they ought to " know. This plan rejects all declamation, all parade, all " wrangling, all subtility: to make a show, and to appear " learned and ingenious in natural knowledge, may flatter " vanity; to know facts, to separate them from suppositions, X PREFACE* " to range and connect them, to make them plain to ordinary capacities, and, above all, to point out the useful applica- 1 tions—is, in my opinion, much more laudable, and shall be " the object of my ambition*." * Introductory Lecture published by Dr. Huoter. Edinburgh,? Sept. 1793. $ CONTENTS. BOOK I. OF THE BONES, CHAP. I. OF THE FORMATION AND GROWTH OF BONES. 1, Page Xjlistory of the Doctrines of Ossification, - 2 Phenomena of Ossification, 4 Blood Vessels and Absorbents of Bones, and Proofs of the. Deposition and Reabsorption of the Bony Matter, - 10 Nerves of Bones, and Proofs of the Sensibility of Bones, 11 The Process of Ossification described, - - - - 12 1. The various Forms and numerous Points of Ossifica- tion, ... , 13 2. The Heads and Processes of Long Bones, - * ib. 3. The Cavity of Long Bones, - - 14 4. TheCancelli, - - 15 5. The Marrow, - - - - - ib. 6. The Lamellae, or Bony Plates, ... ib. 7. The Holes of Bones, - - - 16 8. The Vessels, - - - IF 9. The Internal Periosteum, - ib. 10. The External Periosteum, - ib. 11. The Cartilages, - - 18 The Callus and Regeneration of Broken Bones.. 20 xii CONTENTS*. CHAP. II.—OF THE SKULL IN GENERAL. 22. Page Importance of the Anatomy of the Skull, " " -if The Tables and Diploe of the Bones of the Skull, ">• Enumeration and short Description of the Bones of the Cra- - 24 mum, - The Sutures, - - • 't Remarks on the Formation, Nature, and Use of Sutures, 2 6 CHAP. III.—DESCRIPTION OF THE ^DIVIDUAL BONES OF THE SKULL. 32. Os Frqntis, _ _ - 32 1. Superciliary Ridge, - - ib. 2. ---------Artery and Nerve, - 33 3. Angular Processes, - ib. 4. Nasal Process, - - - ib. 5. Frontal Sinuses, - - ib. 6. Frontal Ridge or Spine, - - 36 7. Orbitary Process, - ib. OS PARIETALE, - 37 Os Occipitis, 38 i. External Surface, - - - • ib. 1. Transverse Spines, - - ib. 2. Crucial Spines, - * ib. 3. Posterior Tuberosity, 39 ii. Internal Surface, - - - ib. 1. Great Internal Ridge and Tentorium Cerebello Superextensum, - ib. 2. Hollows of the Occipital Bone, - - ib. Processes of the Occipital Bone, - ib. 1. Cuneiform, - - ib. 2. Condyles, - - - ib. Holes, - - 40 1. Foramen Magnum, - - - ib. 2. Hole for the ninth Pair of Nerves, - ib. 3. ----for the Cervical Vein of the Neck, ib. 4. Common Hole, - - ib. Os Temporis, ... - _ ft. Squamous part, . - - 41 Petrous part, - •■ - ib. Processes, 1. Zygomatic, . - i5. 2. Styloid, - - ib. 3. Vaginal,. - - ib. CONfENTSi 4. Mastoid or Mamillary, 5. Auditory, ... Holes, For the Ear, 1. Meatus Auditorius Externus, 3» ■ ■ Internus, 3. Small Hole receiving a Branch from the fifth Pair of Nerves, 4. Stylo-Mastoid Hole, 5. Hole for the Eustachian Tube, For Blood Vessels, 1. For the Carotid Artery, 2. For the Great Lateral Sinus, called the Common Hole, as formed partly by the Temporal, partly by the Occipital Bone, 8. Small Hole on the outside of the Temporal Bone, - Os -Ethmoides, 1. Cribriform Plate, - - 2. Crista Galli, 3. Masai Plate, or Azygous Process, 4. Spongy Bones, 5. Orbitary Plate, or Os Planum, 6. Os Unguis, - 7. Cells, Os Sphanoides, Processes, 1. Ahe, 2. Orbitary process, 3. Spinous process, 4. Styloid process, . 5. Pterygoid processes, 6. Azygous process, - 7. Clynoid processes, Anterior, Posterior, Sella Turcica, and its Cells, Holes, 1. Foramen Opticum, 2.---------Lacerum, 3.---------Rotundum, 4. ---------Ovale, 5. —_—_____ Spinale, 6. Pterygoid, or Vidian Hole, Vol. I. XIV CONTENTS. CHAP. IV.—BONES OF THE FACE AND JAWS. 52. Page Ossa NAsr, - 53 Os Unguis, - - - ib. Ossa Maxillaria Superiora, • - - 54 Processes, 1. Nasal, ... ib. 2. Orbitary, - - ib- 3. Malar, - . . ib. 4. Alveolar, - - - - 55 Antrum Maxillare, or Highmorianum, ib. Holes, 1. Infra Orbitary, - - 57 2. Foramen Incisivum, or Anterior Palatine Hole, - - ib. 3. Posterior Palatine Hole, - - ib. Ossa Palati, - - 58 Processes, 1. Palatal Plate or Process, - - jb. Middle Palatal Suture, - ib. Transverse Palatal "suture, - ib. 2. Pterygoid Process, - - - ib. 3. Nasal Plate or Process, - - 59 4. Orbitary Process, - _ ib. Palatine Cells, - - ib. Ossa Spongiosa, or Turbinata Inferiora, _ ib. Vomer, - - - - - 60 Os MALuE, - - - - 61 Processes, 1. Upper Orbitary, - * - ib. 2. Inferior Orbitary, - _ - ib. 3. Maxillary, - - , - ib. 4. Zygomatic, - _ ft 5. Internal Orbitary, - _ ft, Os Maxillje Inferioris, - .ft^ Processes, - - -62 1. Coronoid, v - ft 2. Condyloid, - _ . ft* 3. Alveolar, - - - 63 Holes, 1. Large Hole on the inner side for the entry of the lower Maxillary Nerve and Artery, 64 2. Mental Hole, - - - ib CONTENTS. XV CHAP. V.—OF THE TRUNK. VIZ. OF THE SPINE, THORAX, AND PELVIS. I. Of the Spine---General View of the Spine—its mo- tions—and the Division of the Vertebra, 64 General Description of a Vertebra, - 65 1. Body of the Vertebra, - _ 66 2. Articulating, or Oblique Processes, ib. 3. Spinous Processes, - - - 67 4. Transverse Processes, - - ib. Vertebrae of the Loins, - _ - ib. Vertebrae of the Back, - . - 68 Vertebrae of the Neck, - - ib. Atlas, - - - 70 Dentatus, - - - ib. Medullary Tube and the Passage of the Nerves, 72 Intervertebral Substance, - - ib. Motions of the Vertebra, - - 73 II. Of the Thorax, i. Of the Ribs. General Description of a Rib----Division of the Ribs into true and false—Form of a Rib, and place of the Intercostal Artery, . ib. The Parts of the Rib, as the Head, Neck—Sur- ** face for articulating with the Transverse Pro- cess—Nature of the Joint and Motion of the Rib—Angle of the Rib, - - 75, 76 Size and Length of the Ribs—The Cartilages of the Ribs, " - - - 76 ii. Of the Sternum, and its three Parts, - 77 III. Of the Pelvis, - - - 79 i. Os Sacrum, - - 80 ii. Os Coccygis, ib. iii. Ossa Innominata, - 82 i. Os Ilium, or Haunch Bone----1. Ala— Spine—Spinous Processes, anterior and posterior----2. Dorsum----3. Costa---- 4. Linea Innominata, - 83, 84 ii. Os Ischium, or Hip-Bone----1. Body---- 2. Tuber----3. Ramus, - 84, 85 iii. Os Pubis, or Share-Bone----Body---- Crest----Ramus, -, - ib. xv; CONTENTS. Page Recapitulation of the chief Points of the Anatomy of ^ the Pelvis, - 86 Size of the Pelvis in Man and Woman, Remarks on the separation of the Bones of the pubes ^ during labour, - CHAP. VI.-BONES OF THE THIGH, LEG, AND FOOT. I. Femur, - - ., i tj_j.. - - ib. ib. 92 ib. ib. 93 ib. 94 ib. ib. ib. 96 ib. ib. 97 98 ib. ib. ib. ib. ib. 101 ib. CHAP. VII—BONES OF THE SHOULDER, ARM, AND HAND. Shoulder, i. Scapula, or Shoulder-blade, 102 1. The flat side of the Scapula, 103 2. The upper flat Surface, - ib. 3. The Triangular Form of the Scapula— Costa—Basis, - - ib. 1. Body, 2. Head, 3. Neck, 4. Trochanter major, 5. Trochanter minor, <- 6. Linea aspera, 7. Condyles, II. Tibia, - 1. Upper head, 2. Body, 3. Lower Head—Inner Ankle, III. Fibula, - 1. Upper • Head, 2. Lower Head—Outer Ankle, IV. Rotula, Patella, or Knee-pan, V. Tarsus, or Instep, 1. Astragalus, 2. Os Calcis, 3. Os Naviculare, 4. 5. 6. 7 i-Cuneiform Bones, J Os Cuboides, VI. Metatarsus and its five Bones, VII. Toe »>— Sesamoid Bones, CONTENTS. xvii _, ■ ., Page 4. The Glenoid, or ArUculating Cavity, 104 5. The Neck, - - ib. 6. The Spine, - ft. 7. The Acromion Process, - 105 8. The Coracoid Process, - - ft. ii. Clavicle, or Collar Bone, . 106 1. The Thoracic End and Joint, ib. 2. The Outer End, and its union with the Scapula, - - ib. II. Arm, Os Humeri, _ - ft. 1. Head, - - 107 2. Neck, - _ ib. 3. Tuberosities, - - - ib. 4. Groove for the Tendon of the Biceps Muscle, - - ib. 5. Ridges leading to the Condyles, ib. 6. Condyles, - - - 108 7. Articulating Surface for the Elbow-joint, and general explanation of the Joint, ib. 8. Hollows for the Olecranon and Coronoid Process of the Ulna, - - 109 III. Ulna and Radius, - - ft, I. Ulna, - _ - ib. 1. Greater Sigmoid Cavity, formed by 1. Olecranon, - - ib. 2. Coronoid Process, - ib. 2. Lesser Sigmoid Cavity for receiving the Head of the Radius, - 110 3. Ridges, - - ib. 4. Lower Head of the Ulna, - - ib. 5. Styloid Process of the Ulna, - ib. II. Radius, - - - 111 1. Body, - - ib. 2. Upper Head, - - ib. 3. Neck, - - ib. 4. Point for the Implantation of the Biceps Flexor Cubiti, - - ib. 5. Lower Head, *- - ib. IV. Hand and Fingers, - - 112, General Explanation of the Hand and Wrist, Carpus, Metacarpus, and Fingers, ib. I. Carpus, or Wrist, - - 113 1. Row forming the Wrist, - ib. 1. Os Scaphoides, - - - ib. 2. Os Lunare, - 114 3. Os Cuneiforme, - ib. 4. Os Pisiforme, - - ib. XV111 CONTENTS. Page 2. Row supporting the Metacarpal Bones, l}* 1. Trapezium, - - *?" o t-_„H___:j ' - lb. 2. Trapezoides, 115 Os Magnum, - ., 4. Os Unciforme, II. Metacarpus, III. Fingers, ib. 116 BOOK II. OF THE MUSCLES. CHAP. I.—MUSCLES OF THE FACE, EAR, AND EYE. I. Muscles of the Face, - - 118 1. Occipito Frontalis, - ib. 2. Corrugator Supercilii, - . - 119 3. Orbicularis Oculi, or Palpebrarum, 120 4. Levator Palpebrse Superioris, - ib. II. Muscles of the Nose and Mouth, - 121 5. Levator Labii Superioris et AlaeNasi, ib. 6.--------------------proprius, - ib. 7. Levator Anguli Oris, or Levator Communis Labiorum, - - 122 8. Zygomaticus Major, - ib. 9.----------Minor, - - ib. 10. Buccinator, - - - ib. 11. Depressor Anguli Oris, - 123 12. Depressor Labii Inferioris, or Quadratus Gens, ib. 13. Orbicularis Oris, - ft. 14. Depressor Labii Superioris, et Al» Nasi, 125 15. Constrictor Nasi, - - - ib. 16. Levator Menti, - - ft. HI. Muscles of the External Ear, - - ft. 17. Superior Auris, - - 105 18. Anterior Auris, - - ft, 19. Posterior Auris, - - - ib. 20. Helicis Major, - - ib. 21. Helicis Minor, - - - ft. CONTENTS. XIX 22 Tragicus, . . P^ 23. Antitragicus, - - ib 24. Transversus Auris, - _ jb" IV. Muscles of the Eye-ball, - 127 General Explanation of these Muscles, _ ft. 25. Rectus Superior, - _ jqs 26. Rectus Inferior, - _ ft. 27. Rectus Internus, - _ ft' 28. Rectus Externus, - . ft' 29. Obliquus Superior, - _ ft| 30. Obliquus Inferior, - - 129 CHAP. II.—MUSCLES OF THE LOWER JAW, THROAT, AND TONGUE. I. Muscles of the Lower Jaw, - - 130 31. Temporalis, - - - ib. 32. Masseter, - - ib! 33. Pteregoideus Internus, or Major, - 131 34. Pteregoideus Externus, or Minor, - ft. II. Muscles of the Throat and Tongue, - ft. Explanation of certain Bones and Cartilages forming the basis of the Throat and Tongue, and the centre of their motions, - - ft. 1. Os Hyoides,—Its Cornua,—Its Appendices, or perpendicular Processes, - ib. 2. Larynx, Trachea, or Windpipe, - 133 1. Scutiform, or Thyroid Cartilage, ib. 2. Cricoid Cartilage, - _ ib. 3. Arytenoid Cartilages, and Rima Glottidis formed by them, - . ib. 4. Epiglottis, - - 134 Recapitulation and view of the constitution of the La- rynx* - - ib. i. Muscles of the Throat, _ _ ft. 1. Muscles which pull the Throat down, 135 34. Sterno-hyoideus, - - ft. 35. Sterno-thyroideus, - ib. 36. Omo-hyoideus, - - ib. Action of these Muscles, - - ib. 2. Muscles which move the Throat upwards, ib. 37. Mylo-hyoideus, - - ib. 38. Genio-hyoideus, - - - 136 39. Stylo-hyoideus, - . - ft. 40. Digastricus, or Biventer Maxillae Inferioris, ib. 1. Muscles moving the parts and cartilages of the ■3.X CONTENTS. 138 ib. Page 137 Larynx upon each other, 41. Hyo-thyroideus, - .f 42. Crico-thyroideus, - . " 43. Musculus Arytenoideus Transversus, 44. Musculus Arytenoideus Obliquus, 45. Crico-Arytenoideus Posticus, 46. Crico-Arytenoideus Obliquus, - - «* 47. Thyreo-Arytenoideus, - - }°- 4. Muscles of the Palate and Pharynx, - «>. 48. Azygus Uvulae, - " .^ 49. Levator Palati Mollis, - - t *• 50. Circumflexus Palati, or Tensor Palati Mollis, ib. 51. Constrictor Isthmi Fauschium, - 140 52. Palato-Pharyngeus, - - jh. Pharynx explained, - * J0, 53. Stylo-pharyngeus, - - ib« 54. Constrictor Superior, - 141 55. Constrictor Medius, - - ib. 56. Constrictor Inferior, - - ib. 57. Vaginalis Gulae, - - 142 ii. Muscles of the Tongue, - - ib. 58. Stylo-Glossus, - - ib. 59. Hyo-Glossus, - - ib. 60. Genio-glossus, - - ib. 61. Lingualis, - - - ib. Motions of the Tongue performed by these Muscles, - 143 CHAP. Ill —OF THE MUSCLES OF THE ARM, INCLU- DING THE MUSCLES OF THE SCAPULA, ARM, FORE- ARM, AND HAND. I. Muscles of the Scapula, - - ib. 1. Muscles moving the Scapula upwards and back- wards, - - 144 62. Trapezius, - - ib. 63. Levator Scapulae, or Levator Proprius Angu- laris, - - 145 64 8c 65. Rhomboides, - ft. 1. Minor, - - ft. 2. Major, - ft. ii. Muscles which move the Scapula downwards and forwards, - - 146 66. Serratus Major Anticus, . _ ib. 67. Pectoralis Minor, - - ib. 68. Subclavianus, - - ib. Motions of the Scapula, - - - 147 CONTENTS. xxi H. Muscles moving the Os Humeri, or Arm Bone, if? 69. Pectoralis Major, _ ib< 70. Latissimus Dorsi, - _ 143 71. Deltoides, - . 149 72. Coraco-brachialis, . - 150 73. Supra Spinutus, - „ ft# 74. Infra Spinatus, - _ i5i 75. Teres Minor, « - ib. 76. Teres Major, - _ - ib. 77. Subscapulars, - - 152 Motions of the Humerus, and Use and Effect of each of these Muscles in forming and strength- ening the Joint, - - ft. III. Muscles moving the fore-arm, - 154 i. Muscles bending the i ore-arm, - ft. 78. biceps Brachii Flexor, - - ib. 79. Brachialis Internus, - . ft. ii. Muscles extending the Fore-arm, - 155 80. Triceps Extensor, - ft. 81. Anconeus, - _ _ 155 IV. Muscles situated on the Fore-arm, moving the Radius, Carpus, and Fingkrs, - - ft. Fascia of the Arm, - - ft. Arrangement of these Muscles, the points of ori- gin and insertion, and the motions of pro- nation and supination, flexion, and extension explained, - - ft. i. Flexors, arising from the Inner Condyle, 157 82. Pronator Teres Radii, - I59 83. Palmaris Longus, - - - ib. 84. Palmaris Brevis, or Cutaneus, - 160 85. Flexor Carpi Radialis, - - ft. 86. Flexor Carpi Ulnaris, - 161 87. Flexor Digitorum Sublimis, - ib. 88. Flexor Digitorum Profundus, vel Perforans, 162 89. Lumbricales, - - 163 90. Flexor Longus Pollicis, - 164 91. Pronator Quadratus, - - ft. ii. Extensors arising from the Outer Condyle, 165 92. Supinator Radii Longus, - - ib. 93. Extensor Ca:pi Raciialis Longior, - 166 94. Extensor Carpi Radialis Brevior, - ib. 95. Extensor Carpi Ulnaris, - - 167 96. Extensor Digitorum Communis, - ib. 97. Extensor Minimi Digiti, or Auricularis, 168 98. Extensor Primus Pollicis, "} - 169 99. Extensor Secundus [oliicis, V- - 170 100. Extensor Tertius Pollicis, J - ib. Vol. I. d xxn contents. Page 101. Indicator, - i X79 102. Supinator Brevis, - - *. V. Muscles seated on the Hand, - lb* Table of these Muscles, - lJ2 103. Abductor Pollicis, "") - lb* 104. Opponens Pollicis, I - - 173 105. Flexor Brevis Pollicis, f - ">• 106. Adductor Pollicis, J - - 174 107. Abductor Minor Digiti, "J - p>- 108. Flexor Parvus Minimi Digiti, S- - ib« 109. Adductor Minimi Digiti, J - 175 110. Abductor Indicis, - - ib. ill. Interossei Interni, - - ib. 112. Interossei Externi, - - ib. CHAP. IV—MUSCLES OF RESPIRATION, OR OF THE RIBS. General Explanation and Table of these Muscles, 176 113. Serratus Superior Posticus, - 17f 114. Serratus Inferior Posticus, _ ib. 115. Levatores Costarum, - - 178 116. Intercostales, - . ft. 117. Triangularis Sterni, or Sterno-Costalis, 17» CHAP. V—MUSCLES OF THE HEAD, NECK, AND TRUNK. I. Muscles of the Head and Neck, 118. Splenius, - _ j8q 119. Complexus, - . ft 120. Trachelo-mastoideus, - - 182 121 Rectus Minor, - - ib 122. Rectus Major, _ ft" 123. Obliquus Superior, - . 18-* 124. Obliquus Inferior, - - ib II. Muscles of the Trunk, 125. Quadratus Lumborum, _ . •, 126. Longissimus Dorsi, - - irI 127. Sacro Lumbalis, _ -las 128. Cervicalis Descendens, - - "h 129.. Transversalis Colli, _ j 8 ' contents. Arrangement of the intricate set of Muscles filling up the hollows and interstices among the Spines and Processes of the Vertebrae, - 130. Spinalis Cervicis, 131. Spinalis Dorsi, 132. Semi-spinalis Dorsi, 133. Multifidus Spinse, 134. Inter-spinales Colli, Dorsi, et Lumborum, 135. Inter-transversales, HI. Muscles on the fore part of the Head and Neck, completing the Catalogue of those belonging to the Spine, - . 136. Platysma Myoides, 137. Mastoideus, 138. Rectus Internus Capitis Major, 139. Rectus Internus Capitis Minor, 140. Rectus Capitis Lateralis, 141. Longus Coili, 142. Scalenus, - CHAP. VI—OF THE MUSCLES OF THE ABDO- MEN, AND OF THE DIAPHRAGM. I. Muscles of the Abdomen, Importance of the Anatomy of the Abdominal Mus- cles,—General Explanation of these Muscles,— their Uses,—Arrangement, 143. Obliquus Externus, - 144. Obliquus Internus, 145. Transversalis Abdominis, 146. Recti, 147. Pyramidalis, Explanation of the Lines, Rings, Sec. of the Abdo- minal Muscles, - 1. Linea Alba, 2. Linea Semilunaris, 3. Sheath for the Rectus, 4. Umbilicus, 5. Ring of the Abdominal Muscles, 148. Cremaster Muscles of the Testicle, 6. Ligament of the Thigh, Explanation of the different kinds of Hernia, and the points at which the bowels are pro- truded, Uses of the Abdominal Muscles, XXIV contents. Pag« II. Diaphragm, ... - 200 149. The Diaphragm, - - lb* 1. The Greater, or Upper Muscle of the Diaphragm, - - *b. 2. The Lesser Muscle of the Diaphragm, ib. 3. The Tendon in the centre of the Dia- phragm, - - 201 Vessels perforating the Diaphragm, ib. 1. Aorta, - - |b* 2. Oesophagus, - " ro* 3. The Great Vena Cava, - 202 The Tendon of the Diaphragm, - ib. . / Uses of the Diaphragm, - ib» CHAP. VII—THE MUSCLES OF THE PARTS OF GENERATION, AND OF TFIE ANUS AND PE- RINEUM. General idea of these Muscles, - - 20S Structure of the Penis, ... 204 lsQ. Erector Penis, - - ib. 151. TransversalisPerinaei, - _ ib. 152. Accelerator. - - - ft, 153. Sphincter Ani, - - 205 154. Levator Ani, - . ft. 155. Musculus Coccygaeus, - - 206 Perinxum,—the point where all these Muscles are united, ib. Course of the Incisional Lithotomy, _ . ft, CHAP. VIII—MUSCLES OF THE THIGH, LEG, AND FOOT. I. Muscles moving the thigh bonf, - _ 207 General Description of these Muscles,—Classification and Arrangement of them—and Table of their Implantations, and of the Motions which they perform, - 20S Fascia of the Thigh, _ •• 156. Musculus Fascialis, or Tensor Vagina Fe- rooris, . _ . 2Qg 157. Psoas Magnus, _ _ 21Q 158. Psoas Parvus, . - ib 159. Iliacus Internus, - . ft* CONTENTS. XXV 160. Pectineus, or Pectinalis, - 2fL 161. Triceps Femoris, _ . ft 1. Adductor Longus, - 212 2. Adductor Brevis, _ ft 3. Adductor Magnus, - - ft' 162. Obturator Externus, - . - 213 163. Gluteus Maximus, - - . 214 164. Gluteus Medius, or Minor, - ' ib. 165. Glutxus Minimus, - - ib 166. > n 167. {Gemmi» " - 215 168. Pyriformis, ft, 169. Obturator Internus, - - - ib. 170. Quadratus Femoris, - - _ 216 Motions of the Thigh, and Action of these Muscles, ib. II. Muscles of the Leg, Arrangement of these Muscles, _ 217 i. Extensors of the Leg, - 218 171. Rectus Femoris, or Rectus Cruris, . ft. 172. Crurseus, - - ft. Sub-crurai, being slips only of the Crurseus, 219 173. Vastus Externus, - ib. 174. Vastus Internus, - _ ft. Uses of these Muscles, - 220 ii. Flexors of the Leg, _ _ ib. 175. Sartorius, - ft# 176. Gracilis, or Rectus Internus Femoris, 221 177. Semitendinosus, - _ 222 178. Semimembranosus, . _ ib. 179. Poplitsus, - _ 223 180. Biceps Cruris, - ft. III. Muscles of the Foot, Arrangement, - - 224 i. Extensors, - - ft. 181. Gastrocnemius, - - ib. 182. Soleus, - - - ib. 183. Plantaris, - - 225 184. Peronsus Longus, - - 226 185. Peronxus Brevis, - ib. 186. Tibialis Posticus, - - 227 ii. Flexor, - - 228 187. Tibialis Anticus, - _ ft. IV. Muscles of the Toes. - - ib. 188. Flexor Longus Pollicis, - 229 189. Flexor Longus Digitorum Pedis, Perforans, ib. 190. Massa Carnea J. Sylvii, or Plantse Pedis, 230 191. Flexor Brevis Digitorum, - - ib. 192. Lu rubricates, - - 231 XXV1 CONTENTS. Page 193. Extensor Longus Digitorum Pedis, 231 194. Peronueus Tertius, - - 232 195. Extensor Digitorum Brevis, - lb« 196. Extensor Pollicis Proprius, - 23S lid. Crucial Ligament, - - *f* 197. Abductor Pollicis, ") - jb. 198. Flexor Brevis Pollicis, f " " . 199. Adductor Pollicis, J - »b- 200. Transversalis Pedis, - 335 201. Abductor Minimi Digiti, - jb. 202. Flexor Brevis Minimi Digiti, - ib. 203. Interossei Interni, - - ib« 204. Interossei Externi, - - 236 Plantaris Aponeurosis, - ib. CHAP. IX.—OF THE MUSCULAR POWER. CHAP. X—OF THE TENDONS, LIGAMENTS, BURSjE, AND ALL THE PARTS WHICH BE- LONG TO THE BONES OR MUSCLES, OR WHICH ENTER INTO THE CONSTITUTION OF A JOINT. General Explanation of the Tendons, Ligaments, &c. 248 Of the Forms of the Cellular Substance, - - 250 1. Its Cells, and their use, - - ib. 2. Bursa; Mucosae, ■- - ib. 3. Vaginas or Fascix, - - 251 4. Tendons, - - ft. 5. Periosteum, - - - 252 6. Vagina, or Sheaths of Tendons, - ib. 7. Capsules of the Joints, - - 253 8. Ligaments of Joints, - ft. Recapitulation and Review of the connections of these parts, ib. Constitution and Nature of those less feeling parts,—almost insensible in health,—slow to inflame,—their inflammation very violent, though slow,—diseases to which they are liable, 254 BOOK III. OF THE JOINTS. CHAP. I—JOINTS OF THE HEAD AND TRUNK. I. Joints of the Head and Spine, . __ 258 The Motions of the Head and Spine, _ ft. CONTENTS. XXV11 Page The Provisions for these Motions, - 259 i. Joint of the Head with the Neck, - ib. 1. Articulation of the Occiput and Atlas, ib. Form of the Joint and Capsules for the Condyles, ib. Flat membranous Ligament from the Ring of the Atlas to the Ring of the Occipital Hole, ib. 2. Articulation of the Atlas with the Dentatus, ib. Capsules betwixt the Condyles of the Vertebra;, ib. Transverse Ligament embracing the Neck of the Tooth-like Process----Capsular Ligament, ib. Ligament betwixt the Tooth-like Process and Occipital Hole, - - ib. ii. Joints of the Common Vertebrae with each other, ib. Intervertebral Substance, and Intervertebral Ligaments, 260 External or Anterior Vagina, or Ligament of the Spine, - ft. Internal Ligaments, - - 261 Ligamenta Subflava Crurum Processuum Spi- nosorum—Membranas Interspinals—Liga- menta Processuum Transversorum, - ib. Posterior or Internal Ligament of the Spine, ib. Apparatus Ligamentosus Colli, ' - ib. II. Joint of the Lowkr Jaw, _ - 262 III. Joints of the Ribs, - - 263 Ligamenta CapitelliCostarum, - - ib. Ligamentum Transversarium Externum, ib. ---—•.---- ■-----:-------Internum, ib. Capsule and Ligaments belonging to the Cartilages, 264 CHAP. II—JOINTS OF THE SHOULDER, ARM, AND HAND. I. Joints of the Clavicle, - - ib. With the Sternum, - - ib. With the Scapula, - - 265 II. Joint of the Shoulder, _ ib. III. Joint of the Elbow, - - 267 The General Capsule of the whole Joint, ib. The Lateral Ligaments, External and Internal, ib. The Coronary Ligament of the Ulna, 268 Accessory Ligaments, - ib. IV. Wrist, - - ib. Articulation of the Scaphoid and Lunated Bones with the Scaphoid Cavity of the Radius, - 269 Articulation of the Radius with the Ulna for the tur- ning Motions of the Hand, - ib. Articulation of the Bones of the Carpus with each other, ib. XXVU1 CONTENTS. Page Articulations of the Metacarpus, • 270 V. Joints of the Fingers, - • ib. CHAP. Ill—JOINTS OF THE THIGH, LEG, AND ANKLE. I. The Hip-Joint, - - _ 272 The Ligamentum Labri Cartilaginei Transversale, ib. The Capsule of the Joint, - - ib. The Internal Ligaments, - - 273 II. Knek-joint, - - 274 1. The External Ligaments, -v ib. .' Capsule—and Ligamentum Posticum Winslowii, 275 Lateral Ligaments, - - ib. Ligamentum Laterale Internum, - ib. -------------------Externum Longior, ib. ..... ----■ Brevior, . ib. 2. The Internal or Crucial Ligaments of the Knee, 276 Posterior Crucial Ligament, - ib. Anterior---- ■ ■ , - - ib. Semilunar, or moveable Cartilages, - ib. Ligamentum Mucosum—and Ligamentum Alare Majus et Minus, - - 277 Bursas Mucosae of the Knee-joint, - 278 Recapitulation, explaining the Constitution of this Joint, and uses of its several parts, - ib. III. Articulation of the Fibula with the Tibia, 280 IV. Ankle-Joint, _ _ ft. Ligamentum Superius Anticum, - ft. -------------------Posticum, - ft. ----------Inferius Posticum, _ ib. Capsule, - . 281 Ligamentum Deltoides, - _ ft. ----------Fibulae Anterius, - ib. ----------------Perpendiculare, . ib. --------Inter Fibulam et Astragalum Posterius, ib. V. Joints of the Foot, " - ib Articulations of the Bones of the Tarsus with each other, 282 Joints of the Metatarsus and Toes, . ft. Aponeurosis Plantaris Pedis, - _ ft] Bursal Mucosx of the Ankle and Foot, 283* Conclusion and Enumeration of the Joints, - 284 THE ANATOMY OF THE BONES, MUSCLES, AND JOINTS. BOOK I. OF THE BONES. CHAP. I. OF THE FORMATION AND GROWTH OF BONES. IT is not easy to explain, in their natural order, the various parts of which the human body is composed ; for they have that mutual dependence upon each other, that continual circle of action and re-action in their various functions, and that in- tricacy of connection, and close dependence, in respect of the individual parts, that, as in a circle there is no point of preference from which we should begin to trace its course, so in the human body there is no function so insulated from the other functions, no part so independent of other parts, as to determine our choice. We cannot begin without hesitation, nor hope to proceed in any perfect course ; yet, from whatever point we begin, we may so return to that point, as to represent truly this consent of functions, and connection of parts, by which it is composed into one perfect whole. The bones are framed as a basis for the whole system ; fit- ted to support, defend, and contain the more delicate and noble organs. They are the most permanent and unchange- able of all parts of the body. We see them exposed to the seasons, without suffering the smallest change ; remaining for ages the memorials of the dead; the evidence of a former race of men exceeding ours in strength and stature ; the only remains of creatures which nd longer exist; the proofs of such changes on our globe, as we cannot trace but by these uncer- Vol. I. A 2 OF THE FORMATION tain marks. Thus we are apt to conceive, that even m th living body, bones are hardly organized; scarcely partakinS of life; not liable, like the soft parts, to disease and deatn. But minute anatomy, the most pleasing part of our science, unfolds and explains to us the internal structure of the bones ; shows their myriads of vessels ; and proves them to be as lull of blood as the most succulent and fleshy parts; having, like them, their periods of growth and decay ; being as liable to accidents, and as subject to internal disease. The phenomena of fractured bones first suggested some in- distinct notions of the way in which bone might be formed. It was observed, that in very aged men, a hard crust was often formed upon the surface of the bones ; that the fluid ex- uding into the joints of gouty people, sometimes coagulated into a chalky mass ; Le Dranhad seen in a case of spina ven- tosa, or scrophulous bone, an exudation which flowed out like wax, and hardened into perfect bone ; Daventer had seen the juice that exuded from a split in a bone, coagulate into a bony crust; and it was thought to be particularly well ascertained, that callus was but a coagulable juice, which might be seen exuding directly from the broken ends of a bone, and which gradually coagulated into hard bone. The best physiologists did not scruple to believe, that bones, and the callus of broken bones, were formed of a bony juice, which was deposited by the vessels of the part, and which passing through all the suc- cessive conditions of a thin uncoagulated juice, of a transpa- rent cartilage, and of soft and flexible bone, became at last, by a slow coagulation, a firm, hard, and perfect bone ; de- pending but little upon vessels or membranes, either for its generation or growth, or for nourishment in its perfect state. But this coagulation is a property of dead matter, which has no place in the living system ; or if blood or mucus do ever coagulate within the body, it is only after it is separated from the system. Coagulation is a sort of accident in the living body ; and it is not to be believed that the accidental concourse of parts should form the perfect system of a living bone ; nor that coagulation, an irregular uncertain process, should keep pace with the growth of the living parts ; that a bone which is completely organized, and a regular part of the living system, should, in all its progress towards this perfect state, be merely inanimate, inorganized matter: yet this opinion once prevailed ; and if other theories were at that time proposed, they did not vary in any very essential point from this first notion. De Heide, a surgeon of Amsterdam, believed that bone or callus was not formed from a coagulable juice, but from the blood itself. He broke the bones of ani- AND GROWTH OF BONES. O mals, and, examining them at various points of time, he ne- ver failed (like other speculators) to find exacdy what he de- sired to find. In " every experiment," he found a great effu- sion of blood among the muscles, and round the broken bone : and he as easily traced this blood through all the stages of its progress ; on the first day red and fluid ; by and by coagula- ted ; then gradually becoming white, then cartilaginous, and at last (by the exhalation of its thinner parts) hardening into perfect bone. It is very singular, that often those who abjure theory, and appeal to experiments, who profess only to deliver facts, are least of all to be trusted ; for it is theory which brings them to try experiments, and then the form and order ; and even the result of such experiments, must bend to meet the theories which they were designed to prove. It is by this decep- tion that the authors of two rival doctrines arrive at opposite conclusions by facts directly opposed to each other. Du Ha- mel believed, that as the bark formed the wood of a tree, add- ing, by a sort of secretion, successive layers to its growth ; so the periosteum formed the bone at the first, renewed it when spoiled or -cut away, and, when broken, assumed the nature of bone, and repaired the breach. He broke the bones of pigeons, and, allowing them to heal, he found the perios- teum to be the chief organ for reproducing bone. He found that the callus had no adhesion to the broken bone, and was easily separated from the broken ends which remained rough and bare. And, in pursuing these dissections, he found the periosteum fairly glued to the external surface of the new bone ; or he found rather the callus or regenerated bone to be but a mere thickening of the periosteum, its layers being sepa- rated, and its substance swelled. On the first days he found the periosteum thickened, inflamed, and easily divided into many lamellae, or plates ; but while the periosteum was suffer- ing these changes, the bone was in no degree changed. On the following days, he found the tumor of the periosteum in- creased at the place of the fracture, and extending further along the bone ; its internal surface already cartilaginous, and always tinged with a little blood, which came to it through the vessels of the marrow. He found the tumor of the peri- osteum spongy, and divisible into regular layers, while still the ends of the bone were unchanged, or only a little rough- ened by the first layer of the periosteum being already con- verted into earth and deposited upon the surface of the bone : and in the next stage of its progress, he found the periosteum finnlv attached to the surface of the callous mass. By wound- ing, not breaking, the bones, lie had still a more flattering ap- 4 OF THE FORMATION pearance of a proof; for having pierced them with holes, he found the holes filled up with a sort of tompion, proceeding from the periosteum, which was thickened all round them. In an early stage, this plug could, by drawing the periosteum, be pulled out from its hole : in a more advanced stage, it was inseparably united to the bone, so as to supply the loss. Haller, doubting whether the periosteum, a thin and deli- cate membrane, could form so large a mass of bone or callus, repeated the proofs ; and he again found quite the reverse ot all this : that the callus, or the original bone, was in no de- gree dependent on the periosteum, but was generated from the internal vessels of the bone itself: that the periosteum did indeed appear as early as the cartilage which is to produce the bone, seeming to bound the cartilage, and give it form ; but that the periosteum was at first but a loose tissue of cellu- lar substance, without the appearance of vessels, or any mark of blood, adhering chiefly to the heads or processes, while it hardly touched the body of the bone. He also found that the bone grew, became vascular, had a free circulation of red blood, and that then only the vessel of the periosteum began to carry red blood, or to adhere to the bone. We know that the bones begin to form in small nuclei, in the very centre of their cartilage, or in the very centre of the yet fluid callus, far from the surface, where they might be assisted by the pe- riosteum ; and that ossification begins first in the middle of the long bones, where the periosteum does not adhere, and is formed much later in the heads and processes, whose connec- tion with the periosteum is very close. Thus has the formation of bone been falsely attributed to a gelatinous effusion, gradually hardened ; or to that blood which must be poured out from the ruptured vessels round a fractured bone ; or to the induration and change of the peri- osteum, depositing layer after layer, till it completed the form of the bone. But when, neglecting theory, we set ourselves to examine, with an unbiassed judgment, the process of nature in forming the bones, as in the chick, or in restoring them, as in broken limbs, a succession of phenomena present themselves, the most orderly, beautiful, and simple, of any that are recorded in the philosophy of the animal body : for if bones were but condensed gluten, coagulated blood, or a mere deposition from the periosteum, they were then inorganized, and out of the system, not subject to change, nor open to disease ; liable indeed, to be broken, but without any means of being healed again : while they are, in truth, as fully organized, as per- meable to the blood, as easily hurt, and as easily healed, a* AND GROWTH OF BONES. 5 sensible to pain, and as regularly changed as the softer j>arts are. We are not to refer the generation and growth of bone to any one part. It is not formed by that gelly in which the bone is layed ; nor by the blood which is circulating in it; nor by the periosteum which covers it; nor by the medullary membrane with which it is lined : but the whole system of the bone, of which these are parts only, is designed and planned, is laid out in the very elements of the body, and advances to ripeness by the concurring action of all its parts. The arte- ries, by a determined action, deposite the bone ; which is for- med commonly in a bed of cartilage, as the bones of the leg or arm are ; sometimes betwixt two layers of membrane, like the bones of the skull, where true cartilage is never seen. Often the secretion of the bony matter is performed in a dis- tinct bag, and there it grows into form, as in the teeth ; for each tooth is formed in its little bag, which, by injection, can be filled and covered with vessels. Any artery of the body may assume this action, and deposite bone, which is some- times also formed where it should not be ; in the tendons and in the joints, in the great arteries, and in their valves, in the flesh of the heart itself, or even in the soft and pulpy substance of the brain. All the bones of the body, both in the human foetus, and in other animals, are merely cartilage before the time of birth. The whole foetus is gelatinous ; the bones are a pure, almost transparent and tremulous gelly; they are flexible, so that a long bone can be bent into a complete ring ; and no opacity, nor spot of ossification is seen. This cartilage is never hardened into bone; but, from the first, it is in itself an organized mass. It has its vessels ; which are at first transparent, but which soon dilatf, and whenever the red colour of the blood begins to appear in them, ossification very quickly follows, the arteries being so far en- larged as to carry the coarser parts of the blood. .The first mark of ossification is an artery, which is seen running into the centre of the gelly in which the bone is to be formed. Other arteries soon appear; overtake the first; mix with it and form a-net-work of vessels ; then a centre of ossification begins, stretching its rays according to the length of the bone, and then the cartilage begins to grow opaque, yellow, brittle ; it will no longer bend, and the small nucleus of ossification is felt in the centre of the bone, and .when touched with a sharp point, is easily known by its gritty feel. Other points of ossi- fication are successively formed ; the ossification being always foretold by the spreading of the artery, and by the arrival of red blood. Even- point of ossification has its little arteries, & OF THE FORMATION and each ossifying nucleus has so little dependence on the car- tilage in which it is formed, that it is held to it by these arte- ries only; and when the ossifying cartilage is cut into thin slices, and steeped in water till its arteries rot, the nucleus of ossification drops spontaneously from the cartilage, leaving the cartilage like a ring, with a smooth and regular hole where the bone lay. The colour of each part of a bone is proportioned exactly to the degree in which its ossification has advanced. When ossification begins in the centre of the bone, redness also ap- pears ; indicating the presence of those vessels by which the bony matter is to be poured out. When the bony matter be- gins to accumulate, the red colour of those arteries is obscured, the centre of the bone becomes yellow or white, and the colour seems to be removed towards the ends of the bone. In the centre, the first colouring of the bone is a cloudy, diffused and general red, because the vessels are profuse. Beyond that, at the edges of the first circle, the vessels are more scattered, and distinct trunks are easily seen, forming a circle of radia- ting arteries, which point towards the heads of the bone. Beyond that, again, the cartilage is transparent and pure, be- ing yet untouched with blood ; the arteries have not reached it, and its ossification is not begun. Thus, a long bone, while forming, seems to be divided into seven variously coloured zones. The central point of most perfect ossification is yel- low and opaque. On either side of that, there is a zone of red. On either side of that again, the vessels being more scattered, form a vascular zone,* and the zone at either end is transparent or white. The ossification follows the vessels, burying and hiding those vessels by which it is formed: the yellow and opaque part expands and spreads along the bone : the vessels advance towards the heads of the bones: the whole body of the bone becomes opaque, and there is left only * It is curious to observe how completely vascular the bone of a chicken is be- fore the ossification have fairly begun ; how the ossification having begun, over- takes the arteries, and hides them, changing the transparent and vascular part of the bone into an opaque white; how, by peeling off the periosteum, bioody dots are seen, which shows a living connection and commerce of vessels betwixt the periosteum and the bone ; how, by tearing up the outer layers of the tender bone, the vascularity of the inner layers is again exposed. But of all the proofs of the' vascularity of bones and deposition of the bony matter, the most beautiful is that of our common preparations; where, after filling with injection the arteries of an adult bone, by its nutritious vessels, we, by corroding the bone with mineral acids, dissolve the earth, leaving nothing but the transparent gelly, and thus re- store the bone to its original cartilaginous state ; then the vessels appear in such profusion, that the bone may be compared in vascularity with the soft parts, and it is seen that its arteries were not annihilated, but its high vascularity only'con- cealed by the deposition of the bony parts AND GROWTH OF BONES. 7 a small vascular circle at either end: the heads are separated from the body of the bone by a thin cartilage ; and the vessels of the centre, extending still towards the extremities of the bone, perforate that cartilage, pass into the head of the bone, and then its ossification also begins, and a small nucleus of ossification is formed in its centre. Thus the heads and the body are, at the first, distinct bones formed apart and joined by a cartilage ; and they are not united till the age of fifteen or twenty years. The vessels are seen entering in one large trunk (the nutri- tious artery) into the middle of the bone: from that centre they extend in a radiated form towards either end, and the fibres of the bone are radiated in the same direction ; there are furrows betwixt the rays, and the arteries run along in the furrows of the bone, as if the arteries were forming these ridges, secreting and pouring out the bony matter, each arte- ry piling it up on either side to form its ridge. The body of the bone is supplied by its own vessels ; the heads of the bone are supplied by the extremities of the same trunks which per- forate the dividing cartilage like a sieve ; the periosteum ad- hering more firmly to the heads of the bone, it brings assistant arteries from without, which meet the internal trunks, and assist the ossification ; but with every help, the ossification is not accomplished in many years. It is by the action of the vessels that all the parts of the hu- man body are formed ; fluids and solids, each for its respec- tive use. The blood is formed by the action of the vessels, and all.the fluids are in their turn formed from the blood. We see in the chick, where there is no external source from which its red blood can be derived, that red blood is formed within its own system. Every animal system, as it grows, assimi- lates its food, and converts it to the animal nature, and so in- creases the quantity of its red blood : and as the red blood is thus prepared by the actions of the greater system, the actions of particular vessels prepare various parts : some to be added to the mass of solids, for the natural growth ; others to supply the continual waste ; others to be discharged from the body as effete, and hurtful, or to allow new matter to be received; others again to perform certain offices within the body, as the secretion of semen, of saliva, of bile, or of urine. Thus the body is furnished with various apparatus for performing vari- ous offices, and for repairing the waste. These are the secre- tions, and the formation of bone is one of these. The plan of the whole body lies in the embryo, in perfect order, with all its forms and parts. Cartilage is laid in the place of bone, and preserves its form for the future bone, with all its appara- 8 OF THE FORMATION tus of surrounding membranes, its heads, its processes, and its connection with the soft parts. The colourless arteries of this pellucid, but organized mass of cartilage keep up its growth ; extend, and yet preserve its form; and gradually en- larging in their own diameter, at last receive the entire blood. Then the deposition of earthy matter begins. The bone is deposited in specks, which spread and meet, and form them- selves into perfect bone. While the bone is laid by arteries, the cartilage is conveyed away by the absorbing vessels ; and while they convey away the superfluous cartilage, they model the bone into its due form; shape out its cavities, cancelli, and holes ; remove the thinner parts of the cartilage, and harden it into due consistence. If such organization of arteries to deposite bone, and of absorbents to take up the cartilage and make room for the os- seous matter, be necessary in the formation and growth, it is no less necessary for the life and health of the full formed bone. Its health depends on the regular deposition and re-absorption- moulding and forming the parts ; and by various degrees of action, bone is liable to inflame, to ulcerate, to rot and spoil, to become britde by too much secreted earth, or to become soft by a greedy diseased absorption of its earthy parts. The earth, which constitutes the hardness, and all the useful pro- perties of bone, is dead, inorganized, and lies in the intersti- ces of the bone ; where it is united with mucus, to give it consistence and strength ; furnished with absorbents to keep it in health, and carry off its wasted parts ; and pervaded by vessels to supply it with new matter. The cartilage is itself a secretion, to which the full secretion of bone succeeds, as the arteries grow stronger in their secreting office: for in a broken limb there is first a thin effusion, then a tremulous gelly, then radiated vessels, then ossifying spots, and these running to- gether form perfect bone. If the broken limb be too much moved during the cure, then the secreting arteries are inter- rupted in their office ; perfect bone is never formed; it re- mains a cartilage ; and an unnatural joint is produced: but we cut the surface of these cartilages, and then the vessels are opened again, the process is renewed, and the bones unite: or even by rubbing, by stimulating, by merely cutting the sur- rounding parts, the vessels are made active, and their secre- tion is renewed. During all the process of ossification, the absorbents proportion their action to the stimulus which is ap- plied to them ; they carry away the serous fluid, when gelly is to take its place ; they remove the gelly, as the bone is laid ; they continue removing the bony particles also, which (as in a circle) the arteries continually renew. AND GROWTH OF BONES. § Nothing can be more curious than this continual renovation and change of parts, even in the hardest bones. We are ac- customed to say of the whole body, that it is daily changed ; that the old particles are removed ; and new ones supply their place ; that the body is not now the same individual body that it was ; but it could not be easily believed that we speak only by guess concerning the softer parts, what we know for cer- tain of the bones. It was discovered by chance, that animals fed upon the refuse of the dyer's vats, received so much of the colouring matter into the system, that the bones were tinged by the madder to a deep red, while the softer parts were un- changed ; no tint remaining in the ligaments nor cartilages ; in the membranes, vessels, nor nerves ; not even in the delicate vessels of the eye. It was easy to distinguish by the micro- scope, that such colour was mixed with the bony matter, and resided in the interstices only, but did not remain in the ves- sels of the bone, which like those of all the body had no tinge of red ; while our injections again fill the vessels of the bone, make all their branches red, but do not affect the colours of the bony part. When madder is given to animals, withheld for some time, and then given again, the colour appears in their bones; is removed ; and appears again, with such a sud- den change as proves a rapidity of deposition and absorption exceeding all likelihood or belief. All the bones are tinged in twenty-four hours : in two or three days their colour is very deep : and if the madder be left off but for a few days, the red colour is entirely removed. This tinging of the bones with madder, was the great in- strument employed by Du Hamel, for proving by demonstra- tion, that it was by layers from the periosteum that the bone was formed ; and how very far the mind is vitiated by this vanity of establishing a doctrine on facts, is too easily seen here. As Du Hamel believed that the periosteum deposited successive layers, which were added to the bone, it was his business to prove that the successive layers would be deposited alternately red, white, and red again, by giving a young ani- mal madder, withholding it for a Tittle while, and then begin- ning again to give it. Now, it is easy to foresee that this tinging of the lamellae should correspond with the successive times in which the periosteum is able to deposit the layers of its substance ; but Du Hamel very thoughtlessly makes his layers correspond only with the weeks or months in which his madder was given or withheld. It is easy to foresee also, that if madder be removed from the bones in a few days (which he himself has often told us,) then his first layer, viz. of red bone, could not have waited for his layer of white to Vol. I. B 10 OF THE FORMATION be laid above it% nor for a layer of red above that again, so as to enable him to show successive layers : and if madder can so jpenetrate, as to tinge all the bones that are already formed, then, though there might be first a tinged bone, then a white and colourless layer, whenever he proceeded to give madder for tinging a third layer, it would pervade all the bone, tinge the layer below, and reduce the whole to one tint. If a bone were thus to increase by layers, thick enough to be visible, and of a distinct tint; and if such layers were to be continually accumulated upon each other every week, what kind of a bone should this grow to ? Yet such is the fascinating nature of a theory, that Du Hamel, unmindful of any interruptions like these, describes boldly his successive layers ; carrying us through regular details, experiment after experiment, till at last he brings up his report to the amount of five successive layers, viz. two red layers, and three white ones: nay, in one experiment he makes the tinge of the madder continue in the bones for six months, forming successive layers of red and white ; although, in an earlier experiment (which he must have forgotten in his hurry,) he tells us, that by looking through the transparent part of a cock's wing, he had seen the tinge of the madder gradually leave the bones in a few days. These experiments are as gross and palpable as the occa- sion of them ; and should stand as a warning to us, showing how severely and honestly we ought to question our own judgment, when we aim at confirming our preconceived theo- ries by experiments and facts. Yet by these experiments with madder, one most important fact is proved to us ; that the arteries and absorbents, acting in concert, alternately deposite and reabsorb the earthy parti- cles, as fast as can be conceived of the soft parts, or even of the most moveable and fluctuating humours of the body. The absorption of the hardest bones is proved by daily obser- vation. When a carious bone disappears before the integu- ments are opened ; when a tumour, pressing upon a bone, de- stroys it; when an aneurism of the temporal artery destroys the skull; when an aneurism of the heart beats open the tho- rax, destroying the sternum and ribs ; when an aneurism of the ham destroys the thigh-bone, tibia, and joint of the knee ; when a tumour coming from within the head, forces its way through the bones of the skull;—in all these cases, since the bone cannot be annihilated, what can happen, but that it must be absorbed and conveyed away ? If we should need any stronger proofs than these, we have molities ossium ; a dis- ease by which, in a few months, the bony system is entirelv AND GROWTH OF BONES. Ii broken up, and conveyed away, by a high action of the ab- sorbents, with continual and deep-seated pain, a discharge of the earthy matter by the urine, and a gradual softening of the bones, so that they bend under the weight of the body ; the heels are turned up behind the head ; the spine becomes crook- ed ; the pelvis distorted ; the breast is crushed and bent in: and the functions beginning to fall low, the patient, after a slow hectic fever, long and much suffering of pain and misery, expires ; with all the bones distorted in a shocking degree ; gelatinous, or nearly so, robbed of all their earthy parts ; and so thoroughly softened that they may be cut with the knife. Thus every bone has, like the soft parts, its arteries, veins, and absorbent vessels. And every bone has its nerves too: we see them entering into its substance in small threads, as on the surfaces of the frontal and parietal bones : we see them entering for particular purposes, by a large and peculiar hole, as the nerves which go.into the jaws to reach the teeth: we find delicate nerves going into each bone along with its nutri- tious vessels ; and yet we dare hardly believe the demonstra- tion, since bones seem quite insensible and dead. We have no pain when the periosteum is rasped and scraped from a bone : we have no feeling when bones are cut in amputation i or when, in a broken limb, we cut off with pincers the pro- truding end of a bone : we feel no pain when a bone is tre- panned, or when caustics are applied to it; and it has been always known, that the heated irons which the old surgeons used so much, made no other impression upon the bone than to excite a particular titillation and heat, rather pleasant than painful, running along the course of the bone. But there is a deception in all this. A bone may be exquisitely sensible, and yet give no pain ; a paradox which is very easily explain- ed. A bone may feel acutely, and yet not send its sensation to the brain. It is not fit that parts should in this sense feel, which are so continually exposed to shocks and blows, and all the accidents of life ; which have to suffer all the motions which the other parts require. In this sense, the bones, the cartilages, ligaments, bursae, and all the parts that relate to joints, are quite insensible and dead. A bone does not feel, or its feelings are not conveyed to the brain ; but with this single exception, it shows every mark of life. Scrape a bone, and its vessels bleed ; cut or bore a bone, and its granulations sprout up ; break a bone, and it heals ; or cut a piece of it away, and more bone will be readily produced ; hurt it in any way, and it inflames ; burn it, and it dies : take any proof of sensibility, but the mere feeling of pain, and it will answer 12 OF THE FORMATION to the proof. In short, these parts have a sensibility which belongs to themselves, but have no feelings in correspondence with the general system. # . A bone feels stimuli, and is excited to re-act; injuries pro- duce inflammation in the bones, as in the soft parts ; and then swelling and spongy looseness, and a fullness of blood, sup- puration, ulcer, and the death and discharge of the diseased bone ensue. When the texture of a bone is thus loosened by inflammation, its feeling is roused ; and the hidden sensibili- ty of the bone rises up like a new property of its nature : and as the eye, the skin, and all feeling parts, have their sensibili- ty increased by disease, the bones, ligaments, bursae, and all the parts whose feeling, during health, is obscure and hardly known, are roused to a degree of sensibility far surpassing the soft parts. The wound of a joint is indeed less painful at first, but when the inflammation comes, its sensibility is rais- ed to a dreadful degree : the patient cries out with anguish. No pains are equal to those which belong to the bones and joints. Thus ossification is a process of a truly animal nature : no coagulation will harden cartilage into bone; no change of con- sistency will convert the blood into it; no condensation of the periosteum can assimilate it to the nature of a bone. Bone is not the inorganic concrete which it was once supposed ; but it is a regularly organized part, whose form subsists from the first; and which is perfected by its secreting arteries, balan- ced, as in every secretion, by the absorbents of the part ; it lives, grows and feels ; is liable to accidents, and subject to disease. It is a process which, at first, appears so rapid, that we should expect it to be soon complete ; but it becomes in the end a slow and difficult process. It is rapid at first ; it advances slowly after birth ; it is not completed in the human body till the twentieth year; it is forwarded by health and strength, retarded by weakness and disease. In scrofula it is imperfect; and so children become rickety, the bones soften- ing and swelling at their heads, and bending under the weight of the body. And why should we be surprised, that careless- ness of food or clothing, bad air, or languid health should cause that dreadful disease, when more or less heat, during the incubation of a chick, affects the growth of its' bones • when the sickness of a creature, during our experiments, pro- tracts the growth of callus; when, in the accidents of preg- nancy, of profuse suppuration, or of languid health, the knit- ting of broken bones is delayed, or wholly prevented. This process, so difficult and slow, is assisted by every pro- vision of nature. The progress of the whole is slow, that as And growth of bones. 13 long as the body increases in stature, the bones also may grow ; but it is assisted in the individual parts, where some Are slow ; some rapid in their growth ; some delayed, as the heads of joints, that their bones may be allowed to extend j and others hastened, as the pelvis, that they may acquire their perfect size early in life. Ossification is assisted by the soft- ness of the cartilaginous bed in which the bone is formed ; by those large and permeable vessels which carry easily the gross- er parts of the blood; by a quick and powerful absorption, which all along is modelling the bone; and, most of all, by being formed in detached points, multiplied and crowded to- gether, wherever much bone is required. There is one central ring first ossified in a long bone, as of the leg or arm ; the heads or ends of the bone are at first mere cartilage, but they also soon begin to ossify ; the body stretch- es in a radiated form towards either head ; the heads ossifying each in its centre, also stretch towards the bone ; the heads meet the body, and join to it; a thin cartilage only is inter- posed, which grows gradually thinner till the twentieth year, and then disappears ; the body, heads, and processes, becom- ing one bone. In flat bones, as in the skull, ossification goes from one or more central points, and the radiated fibres meet the radii of other ossifying points, or the edges of the next bone. The thick round bones which form the wrist and foot, h,ave one ossification in their centre, which is bounded by car- tilage all round. The processes are often distinct ossifications joined to the bones, like their heads, and slowly consolidated with them into firm bones.* While the bone is forming, various parts, essential to its system, gradually rise into view. At first, we cannot in the long bone perceive any heads, processes, cavities, or cells ; these parts are very slowly formed, and are perfected only in the adult bone. At first, the whole length of a long bone is represented by a transparent gelly ; where there is no distinction of heads nor processes, it is all of one mass. After the red blood has be- gun to tinge this cartilage, the ossification begins, and one ring is formed in the middle of the bone : from this ring, the fibres stretch towards either end, and stop there; then it begins to appear that the heads and body are distinct parts ; the fibres of the growing bone have extended till the cartilage is annihi- lated, and only a small plate remains, separating the knobs of the heads from the long body of the bone. Thus, there is no distinction betwixt the heads and the body, while the bone is • The processes and heads are named the epiphysis and apophysis of bones. 14 OF THE FORMATION cartilaginous ; they begin to appear, as distinct parts, at that stage in which the body of the bone is ossified, and each of the heads is beginning to form ; they continue three distinct bones, during all the early part of life, and are easily separa- ted, by soaking the bone in water ; when they are separated, there is seen a rough hollow on the surface of the epiphysis, or separated head, and a rough convexity on the end of the body: they are finally united into one bone, about the twen- tieth year. In the original cartilage, there is no hollow, nor cavity ; it is all one solid mass. When the ossification first appears, the cavity of the bone also begins, and extends with the ossifica- tion. At first, the cavity is confined-chiefly to the middle of the bone, and extends very slowly towards the ends. This cavity, in the centre of the bone, is at first smooth, covered by an internal membrane, containing the trunks and branch- ings of the nutritious vessels, which enter by a great hole, in the middle of the bone ; and the cavity is traversed, with divisions of its lining membrane, which, like a net-work of partitions, conduct its branches to all parts of the internal surface of the bone ; and its nets, or meshes, are filled with a reddish and serous fluid, in the young bone, but secrete and contain a perfect marrow in the adult bone. The whole substance of a bone is not only fibrous, as ap- pears outwardly, but is truly lamellated, consisting of many distinct and delicate plates of bone ; which lie over each other in regular order, and might suggest the notion that successive ossifications of the periosteum form the bone. These lamel- lae, or plates, are more condensed and firmer towards the outer surface ; and are more loose, separate, and spongy, towards the internal surface of the bone : and it is easily seen, during the growth of a young bone, that the inner and more delicate plates are separating from the walls of the bone, and receding towards its cavity; and these plates, being again crossed by small bony partitions, form a net-work, or spongy mass, which fills the whole cavity of the bone. In the middle of the bone, the cavity is small, the walls are thick, and have all their bony plates ; the cells of net-work are few, and large : but towards the ends, the bone swells out; the cavity also is large, but it is not like that in the middle, a large tubular cavity; it is so crossed with lattice-work, with small interstices and cells that it seems all one spongy mass of bone ; and so many of the inner layers are separated, to form this profusion of cells that the whole substance of the bone has degenerated into' this AND GROWTH OF BONES. 15 lattice-work, leaving only a thin outward shell.* This reti- cular form is what anatomists call the cancelli, lattice-work, net-work, or alveolar part of the bone ; it is lined throughout with one delicate membrane ; and inward partitions of the same lining membrane cover each division of the lattice-work, forming each cell into a distinct cavity. In these cavities or cells the marrow is secreted. The secretion is thin and bloody in children ; it thickens as we advance in years ; it is a solid oil, or marrow, in the adult. The marrow is firmer, and more perfect in the middle of the bone ; more thin and serous to- wards the spongy ends. The whole mass, when shaken out of the bone, is like a bunch of grapes, each hanging by its stalk. The globules, 'when seen with the microscope, are neat, round, and white, seeming like small pearls, and each stalk is seen to be a small artery, which comes along the mem- brane of the cancelli, spreads its branches beautifully on the surface of the bag, and serves to secrete the marrow, each small twig of artery filling its peculiar cell. To this, an old anatomist added, that they had their contractile power, like the urinary bladder, for expelling their contents ; that they squeezed their marrow, by channels of communication, through and among the bony layers ; and that their oil exuded into the joint, by nearly the same mechanism by which it got into the substance of the bone. While the constitution of a bone was not at all understood, anatomists noted with particular care, every trifling peculiari- ty, in the forms or connections of its parts, and these lamellae attracted particular notice. That a bone is formed in succes- sive plates, is easily seen, as in whalebone ; or in the horns and bones of the larger animals ; in church-yard bones, which have been long buried, or long exposed to the air. It is de- monstrated by a careful picking, and separation of the scales, in a young bone, or by burning a bone, which melts and con- sumes its gelly, and leaves the bony parts entire. It is seen in the common diseases of bones; for they cast off by successive plates, or leaves, whence the process is named exfoliation ; and one plate is thoroughly spoiled and cast off, whilst another is entire, and sound. Malpighi had first observed the lamel- lated structure of bones, likening them to the leaves of a book. Gagliardi, who, like Hippocrates, went among the burial pla- • That it is merely an expansion of the layers that forms the cancelli, and a mere swelling and sponginess of the same quantity of bony substance, that makes the ends so much thicker than the middle, is proved by this, that an inch of the smaller bony tube, cut from the middle, weighs equally with an inch of the large spongy tube, cnt ont from the ends. 16 OF THE FORMATION ces of the city, to observe the bones there, found in a tomb, where the bones had been long exposed, a skull, the os Irontis of which he could dissect into many layers, with the point ot a pin. He afterwards found various bones, from all parts ot the body, thus decomposed ; and he added to the doctrine ot plates, that they were held together by minute processes, which going from plate to plate, performed the offices of nails : these appeared to his imagination to be of four kinds, straight and inclined nails, crooked or hook-like, and some with small round heads, of the forms of bolts or pins.* Another notable discovery, was the use of the holes which are very easily seen through the substance of bones, and among their plates. They are, indeed, no more than the channels by which the vessels pass into the bones; but the older anatomists imagine them to be still more important, allowing the marrow to transude through all the substance of the bone, and keep it soft. Now this notion, of lubricating the earthy parts of a bone, like the common talk about fomen- tations to the internal parts of the body, is very mechanical, and very ignorant; for the internal parts of the body, are both hot and moist of themselves, and neither heat nor mois- ture can reach them from without: the bone is already fully watered with arteries ; it is moist in itself, and cannot be fur- ther moistened nor lubricated, unless by a fuller and quicker circulation of its blood. It must be preserved by that mois- ture alone which exists in its substance, and must depend for its consistence upon its own constitution; upon the due mix- ing up of its gluten and earth. Every part is preserved in its due consistence by the vessels which form its subsistence ; and I should no more suppose fat necessary for preserving the moistness of a bone, than for preventing brittleness in the eye. This marrow is, perhaps, more an accidental deposition, than we at first sight believe. We indeed find in it such a regulari- ty of structure, as seems to indicate some very particular use; but we find exactly the same structure in the common fat of the body. When, as we advance in years, more fat is depo- sited in the omentum, or round the heart, we cannot entertain the absurd notion of fat being needed in our old age, to lubri- cate the bowels or the heart ; no more is the marrow (which is not found in the child,) accumulating in old age for prevent- ing brittleness of the bones. * These nails, which Gagliardi imagined, were no more than the little ir- regularities, risings, and hollows of the adjoining plates, by which they are connected. AND GROWTH OF. BONES. ir The blood vessels of a bone are large, in proportion to the mass of the bone : for first one great trunk enters commonly about the middle of the bone, as in the thigh-bone, leg or arm, and is called the nutritious or medullary artery ; it pene- trates into the central cavity of the bone, spreads upwards and downwards, supplying all the substance of the bone itself, and giving those delicate arteries which secrete the marrow. Other arteries enter from without, at the spongy ends of the bones, where the holes are not visible only, but very large in the adult; particularly large arteries enter into the heads of the bones, as of the shoulder, or of the thigh-bones ; and there the periosteum adheres very strongly : and every where on its surface the bone is supplied by numerous vessels from the periosteum (and this seems, indeed, to be the chief use of that membmne ;) so that in tearing off the periosteum, the surfaces of the membrane, and of the bone, are seen covered with bloody points ; all the vessels are conducted to the sub- stance of the bone by its two membranes : the internal vessels by the membrane which lines the cavity, and which is known by the absurd name of internal periosteum ; the external one by the outer membrane, the proper or external periosteum. The internal periosteum is that membrane which surrounds the marrow, and in the bags of wThich the marrow is formed and contained. It is more connected with the fat than with the bone ; and in animals, can be drawn out entire from the cavity of the bone : but its chief use is to conduct the vessels which are to enter into the substance of the bone ; and this connection and office is so essential to the life and health of the bone, that the spina ventosa, or scrophulous bone, is merely a failure of the internal circulation, a total corruption of the marrow, and a consequent loss of the medullary vessels ; by which the whole bone dies, is thrown out by nature, or more frequently the limb must be cut off. The same effect is pro- duced in our experiments, where, by piercing into the medul- lary cavity, and destroying the marrow, the shaft of the bone dies, while the heads and processes live, merely because they are supplied more fully by their external vessels. The periosteum, which was once referred to the dura mater, is merely condensed cellular substance; of which kind of matter we now trace many varied forms and uses ; for, so close is the connection of the periosteum, tendons, ligaments, % fasciae,- and bursae, and so much are these parts alike in their nature and properties, that we reckon them but as varied forms of one common substance, serving for various uses in different parts. The periosteum consists of many layers, accumulated and condensed one above another : it adheres to the body ®f Vol. L G 18 OF THE FORMATION the bone by small points or processes, which dive into the substance of the outer layer, giving a firm adhesion to it, so that it may bear the pulling of the great tendons, whicn^e fixed rather into the periosteum, than into the bone. it is also connected with the bone, by innumerable vessels, it is not in itself vascular; but it is the medium by which vessels are transmitted to the bone ; and our injections do not easily colour the periosteum itself, while they make the bone which belongs to it thoroughly red. The layers of the periosteum nearest to the bone, are condensed and strong, and take a strong adhesion to the bone, that the vessels may be transmit- ted safely, and the fibres of this inner layer follow the longi- tudinal directions of the bony fibres. The periosteum is looser in its texture outwardly, where it is reticulated and lax, chang- ing imperceptibly into the common cellular substance. There the fibres of the periosteum assume the directions of the mus- cles, tendons, or other parts which run over it. The office of the periosteum is not to generate bone ; and therefore it ad- heres but slightly to the growing bone : it is to nourish the ex- ternal plates ; and therefore as the bone grows, and as the ex- ternal plates are further removed from the medullary vessels, the adhesion of the periosteum becomes closer, its arteries are enlarged, and the dependence of the outer layers on the periosteum is as well proved as the dependence of the body of the bone upon its medullary artery ; for as piercing the me- dulla kills the whole bone, hurting the periosteum kills the outer layers of the bone. Any accident which robs the bone of its periosteum has this effect; accidental wounds of the periosteum, deep ulcers of the soft parts, as on the shin, the beating of aneurisms, the growth of tumours, the pressure even of any external body, will, by hurting the periosteum, cause exfoliation, which is, in plain terms, the death of the external layer, by the injury of the outward vessels ; and an active inflammation of die deeper layers, which being fully nourished by the internal arteries, inflame, swell, become porous and spongy, form granulations, and these granulations push off the mortified plate, and form themselves into new bone, which supplies its place. The cartilages are also part of the living system of the bone : and we see too well, in the question of the bones them- selves, how unphilosophical it must be, to deny organization and feeling to any part of the living body, however dead or • It would appear that the arteries are convertible through time into the&e toeth-Uke processes, by which the periosteum is fixed into the bone ; for in youth, the vessels are numerous, the adhesion slight, and the separation bloody ; but in the older subject, the separation is more difficult, and less blood is seen. AND GROWTH OF BONES. 19 insulated it may appear ; for every part has its degree of life: the eye, the skin, the flesh, the tendons, and the bones, have successive degrees of feeling and circulation. We see, that where even the lowest of these, the bone, is deprived of its small portion of life, it becomes a foreign body, and is thrown off from the healthy parts, as a gangrened limb is separated from the sound body ; and we speak as familiarly of the death of a bone, as of the gangrene of soft parts. How, then, should we deny organization and life to the cartilages, though surely, in respect of feeling, they must stand in the very last degree ? The periosteum goes from the bone over the surface of the cartilage also, where it is named perichondrium : it still pre- serves its own vascular nature ; the vessels can be injected; and it is not to be believed that the perichondrium has these vessels, without communicating them to the cartilage to which it belongs. We see red arteries in the centre of an ossifying cartilage ; and therefore we know that the trunk of the artery may be red, as in the ossifying part of the cartilage, and yet the extremity of the same artery be pellucid, as in the unossi- fied part. Since vessels run through the cartilage to generate bone, we cannot, in reason, suppose that these vessels are produced in the instant in which they appear : they had exist- ed before; they are but dilated now; the increasing action dilates them, and the dilatation makes them red: this enables them to secrete bone, and, in many c^ses, as in the acciden- tal joint formed by a fracture ill cared for, we can, by paring the cartilage, set the vessels free again, and make them begin to secrete. Wherever we find a vascular membrane surrounding and nourishing any part, as the vitreous or crystalline humours in the eye, we must not suppose that such are insulated parts, maintained there by mere adhesion ; but must consider them as parts regularly organized, their vascular membrane being part of their living system ; and though the transparent hu- mours of the eye, the cartilages and ligaments over all the body, and all the system of the bones, have been considered as mere concretes, and insulated parts, they are now known to be regular parts of the living whole. The cartilages have no very active circulation ; it is such as to keep them in life, but not so active as to endanger inflammation ; in the continual shocks which they must endure, their feeling must be very ob- scure ; for feeling also would have been inconsistent with their offices, which is to cover and defend the bones ; to yield to the weight of the body, and to restore themselves when that weight is removed ; to bear all the shocks of leaps or falls ; to 2© OF THE FORMATION perform all the motions of the bodv, and the continual work- ings of the joints where they rub, "and even grate upon each other, without danger or pain. We now understand the constitution of a bone, and can- compare it fairly with the soft parts in vascularity, and nyeel- ing; in quickness of absorption; in the regular supply ot blood necessary to the life of the bony system ; in the certain death of a bone, when deprived of blood by any injury of its marrow, or of its periosteum, as a limb dies of gangrene, when its arteries are cut or tied ; in the continual action of its absorbents, forming its cavity, shaping its processes and heads, keeping it sound and in good health, and regulating the degree of bony matter, that the composition may neither be too brittle nor too soft. From this constitution of a bone, we can easily foresee how the callus for uniting broken bones must be form- ed ; not by a mere coagulation of extravasated juice, but by a new organization resembling the original bone. The primordium of all the parts of the body is a thin gela- tinous mucus, in which the forms of the parts are laid ; and the preparation for healing wounds, and for every new part that needs to be formed, is a secretion of mucus which is soon animated by vessels coming into it from every point. In every external wround, in every internal inflammation, wherever ex- ternal parts are to be healed, or internal viscera are about to adhere, a mucous matter is secreted, which serves as a bed or nidus, in which the vessels spread from point to point, till the mucus is animalized and converted into a membrane : and thus the heart, the intestines, the testicle, and other parts, adhere by inflammation to the coats which surround them, and which are naturally loose. It is a mucus of the same form which unites the ends of a broken bone ; and, by break- ing the bones of animals, and attending to the progress of the callus, we find first a thin mucus ; then that thickened into a transparent gelly ; that gelly growing vascular, and these ves- sels gradually depositing nuclei of ossification in the centre of the mass ; and by madder, or by fine injections, we can make the gelly appear vascular, and the nuclei of ossification quite red. The colours of our injections begin to tinge the carti- lage as it begins to ossify, and as soon as the ossification is general, it receives a general tinge. Now when we find the substance of the oldest bone thus full of vessels, why should we doubt of its being able from its own peculiar vessels, to heal a breach, or to repair any loss ? We have no reason to refer the generation of callus to the marrow, to the periosteum, nor to the substance of the bone itself; for they are but parts of the common system of a AND GROWTH OF BONES. 21 bone ; and each part of this system is of itself capable of re- generating the whole. How little the constitution of a bone has been understood, we may know from the strange debates which have subsisted so long about the proper organ for gene- rating callus. Some have pronounced it to be the periosteum ; others the medullary vessel, and internal membrane ; others the substance of the bone itself : but I have been employed-in explaining, that not only any part of the bone, periosteum, or marrow, but even any artery in all the system, may assume that action which generates bone. In the heat of this dispute,- one of the most eminent anatomists produced a diseased bone, where a new bone had been formed surrounding a carious one, and the spoiled bone rattled within the cavity of the sound one. Here we should have been ready to pronounce, that bone could be formed by the periosteum alone. But presently another anatomist produced the very reverse, viz. a sound young bone, forming in the hollow cylinder of a bone which had been long dead ; where, of course, the callous matter must have been poured into the empty cavity of the spoiled bone, from the ends which still remained sound, or must have been secreted by the medullary vessels. But the truth is, that cal- lus may be thus produced from any part of the system of a bone ; from its periosteum, from its medulla, or from the substance of the bone itself. If we pierce the bone of any animal, and destroy the marrow, the old bone dies, and a new one is formed from the periosteum : if we kill the crea- ture soon, we find the new bone to be a mere secretion from the inner surface to the periosteum ; and if we wait the com- pletion of the process, we find the new bone beautiful, white, easily injected, and thick, loose in its texture, and vascular and bloody, but still firm enough for the animal to walk upon; and in the heart of it, we find the old bone dead and black. If we reverse this operation, and destroy the periosteum only, leaving the nutritious vessels entire, then the new bone is formed fresh and vascular by the medullary vessels, and the old one surrounds it quite black and dead ; and in fractures of the patella, or knee-pan, where there are no medullary ves- sels, the pieces are united by a callus, which is secreted from the vessels of the bone itself. The diseases of the bones are the most frequent in surgery ; and it is impossible to express how much the surgeon is con- cerned in obtaining true ideas of the structure, constitution, and diseases of bones ; how tedious, how painful, and how loathsome these diseases are ; how often the patient must lose his limb, or endanger his life ;; how very useful art is ; but, above all, what wonders nature daily performs in recovering bones from their diseased state. ( 22 ) CHAP. II. OF THE SKULL IN GENERAL—THE BONES OF WHICH IT IS COMPOSED—THEIR TABLES—DIPLOE---SUTURES---THEIR ORIGINAL CONDITION, AND THEIR PERFECT FORM, REPRE- SENTED AND EXPLAINED. WhILE the bones in general serve as a basis for the soft parts, and for supporting and directing the motions of the body, certain bones have a higher use in containing those or- gans whose offices are the most essential to life. The skull defends the brain ; the ribs and sternum defend the heart and lungs ; the spine contains that prolongation of the brain which gives out nerves to all the body : and the injuries of each of these are important in proportion to the value of those parts which they contain. How much the student is interested in obtaining a correct and perfect knowledge of the skull, he must learn by slow de- grees. For the anatomy of the skull is not important in itself only ; it provides for a more accurate knowledge of the brain; explains, in some degree, the organs of sense ; instructs us in all those accidents of the head which are so often fatal, and so often require the boldest of all our operations. The marks which we take of the skull, record the entrance of arteries ; the exit of veins and nerves; the places and uses of those muscles which move the jaws, the throat, the spine. Indeed, in all the human body, there is not found so complicated and difficult a study, as this anatomy of the head ; and if this fatiguing study can be at all relieved, it must be by first estab- lishing a very regular and orderly demonstration of the skull. For this end, we distinguish the face, where the irregular surface is composed of many small bories, from the cranium or skull cap, where a few broad and flat shaped bones form, the covering of the brain. It is these chiefly which inclose and defend the brain, which are exposed to injuries, and are- the subject of operation. It is these also that transmit the nerves. So that the cranium is equally the object of-attention with the anatomist and with the surgeon. All the bones of the cranium are of a flattened form, con- sisting of two tables, and an intermediate diploe, which an- swers to the cancelli of other bones. The tables of the skull are two flat and even plates of bone : the external is thought to be thicker, more spohgy, less easily broken; the thinner OF THE SKULL IN GENERAL. 23 table, again, is dense, thin and brittle, very easily broken, and is sometimes fractured, while the external table remains en- tire : thence it is named tabula vitrea, or the glassy table. • These tables are parted from each other by the distance of a few lines ;* and this space is filled up with the diploe, or can- celli. The cancelli, or lattice work, is a net of membranes, covered with vessels, partly for secreting marrow, and partly for nourishing the bone ; and by the dura mater adhering to the internal surface, and sending in arteries, which enter into the cancelli by passing through the substance of the bone, and by the pericranium covering the external plate, and giving vessels from without, which also enter into the bone, the whole is connected into one system of vessels. The pericranium, dura mater, and skull, depend so entirely, .one upon the other, and are so fairly parts of the same system of vessels, that an injury of the pericranium spoils the bone ; separates the dura mater, and causes effusion upon the brain ; a separation of the dura mater is, in like manner, followed by separation of the pericranium, which had been sound and unhurt; and every disease of the cancelli, or substance of the bone, is communi- cated both ways ; inward to the brain, so as to occasion very imminent danger; outward towards the integuments, so as to warn us that there is disease. The general thickness of the skull, and the natural order of two tables, and an inter- mediate diploe, is very regular, in all the upper parts of the head. In perforating with the trepan, we first cut with more labour, through the external table; when we arrive at the cancelli, there is less resistance, the instrument moves with ease ; there is a change of sound, and blood comes from the tearing of these vessels, which run in the cancelli, betwixt the tables of the skull.. Surgeons thought themselves so well assured of these marks, that it became a rule, to cut freely, and quickly, through the outer table ; to expect the change of sound, and the flow of blood, as marks of having reached the cancelli; and then to cut more deliberately, and slowly, through the inner table of the skull. But this shows an indis- creet hurry, and unpardonable rashness in operation. T^he patient, during this sawing of the skull, is suffering neither danger nor pain ; and many additional reasons lead us to re- fuse, altogether, this rule of practice. For the skull of a child consists properly of one table only; or tables are not * In anatomy there is occasion in almost every description, for a scale of smaller parts. The French divide their inch into twelve parts, each of which" is a line. The French line, or twelfth of an inch, is a measure which I shall often have occasion to use. 24 OF THE SKULL IN GENERAL. yet distinguished, nor the cancelli formed : in youth, the skull has its proper arrangement of cancelli and tables; but still, with such irregularities, and exceptions, as make a hurried operation unsafe : in old age, the skull declines towards its original condition ; the cancelli are obliterated; the tables ap- proach each other, or are closed and condensed into one ; the skull becomes irregularly thick, at some points, and at others thin, or almost transparent:—so that there can hardly be named any period of )ife, in which this operation may be performed quickly and safely at once. But, besides this gra- dual progress of a bone, increasing in thickness and regulari- ty as life advances, and growing irregular and thinner in the decline of life, we find dangerous irregularities, even in youn- ger skulls. There are often at uncertain distances, upon the internal surface of the skull, hollows and defects of the inter- nal table, deep pits, or foveae, as they are called, produced perhaps by the impression of contorted veins. These foveas increase in size and in number as we decline in life ; they are more frequent on the inner surfaces of the parietal and frontal bones ; so that in those places where the skull should be most regular, we are never sure, and must, even in the safest places, perforate gradually and slowly. BONES.—The bones of which the cranium, or skull-cap, is formed, are eight in number. 1. The frontal-bone, or bone of the forehead, forms the upper and fore part of the head,—extends a little towards the temples, and forms also the upper part of the socket for the eye. 2. The parietal bones, are the two large and flat bones which form all the sides, and upper part of the head ; and are named parietalia, as they are the walls or sides of the cranium. 3. The os oc- cipitis, is named from its forming all the occiput or back of the head ; though much of this bone lies in the neck, and is hidden in the basis of the skull. 4. The ossa temporum form the lower parts of the sides of the cranium : they are called temporal, from the hair that covers them being the first to turn grey, marking the time of life. 5. The os ^th- moides, and, 6. the os sphenoides, are quite hidden in the basis of the skull: they are very irregular and very difficultly described, or explained. The os .ethmoides, is a small square bone, hollow,, and with many cells in it; it hangs over the nose, and constitutes a great and important part of that organ, and at the same time supports the brain. The olfac- tory nerves, by passing through it at many points, perforate it like a sieve ; and it takes its name from this perforated or aethmoid plate. The os sphenoides, is larger and more irre- gular still; placed further back j locked in betwixt the occipi- OF THE SKULL IN GENERAL. 25 tal and aethmoidal bones ; lies over the top of the throat, so that its processes form the back of the nostrils and roof of the mouth ; and it is so placed, as to support the very centre of the brain, and transmit almost all its nerves. SUTURES.—All these bones are joined together by seams, which, from their indented, or dove-tailed appearance, are named sutures. 1. The coronal suture, is that which joins the frontal to the parietal bones ; extends almost-directly across the head, from ear to ear ; descends behind the eye, into the deep part of the temple ; and there losjng its serrated appearance, be- comes like the squamous or scaly suture, which joins the tem- poral bones. It is named coronal, because the ancients wore their garlands on this part of the head. But the suture had been better intitled to this name, had it surrounded the head, than as it crosses it. 2. The lambdoidal suture, is that which joins the pa- rietals, to the occipital bone. It begins behind the one ear, ascends, and arches over the occiput, and descends behind the other ear. It thus strides over the occiput, in a form somewhat resembling the letter lambda (a) of the Greeks -9 whence its name. 3. The sagittal suture, joins the parietal bones to each other; runs on the very top of the head; extends forwards from the lambdoidal suture, till it touches, or sometimes passes, the coronal suture ; and from lying betwixt these two sutures, like an arrow betwixt the string and the bow, it has been named sagittal. 4. The temporal sutures, join the temporal bones to the parietal, -occipital, and frontal bones; the sphenoid bone also enters into the temporal suture, just behind the eye. The temporal suture makes an arch corresponding almost with the arch of the external ear; it meets the coronal suture, an inch before the ear, and the lambdoidal an inch behind it. This back part belongs as much to the occipital as to the temporal bone ; and so has been named sometimes additamentum su- turae lambdoidalis ; sometimes additamentum suturae squa- rrtosae : for this temporal suture is, on account of the edge of the temporal and occipital bones being thin, and like scales of armour laid over each other, often named the squamous, or scaly suture. 5. The sphenoidal and ethmoidal sutures, are those which surround the many irregular processes of these two bones, and join them to each other, and to the rest. 6. The transverse suture, is one which, running across the face, and sinking down into the orbits, joins the bones of Vol. I. D •26 OF THE SKULL IN GENERAL. the skull to the bones of the face ; but with so many irregula- rities and interruptions, that the student will hardly recognize this as a suture. 7. The zygomatic suture, is one which joins a branch ot the temporal bone to a process of the cheek-bone ; forming an arch, zygoma, or yoke ; but this suture has little extent; it is a serrated appearance at one single point only. To mark and know these sutures, and to be able to trace them in imagination, upon the naked head, to foresee where a suture will present, and how far it runs, may be a matter of great importance to the surgeon. Hippocrates, who has had more to praise his honesty than to follow his example, ac- knowledges his having mistaken a suture for a fracture of the skull; and since this warning, various contrivances and marks have been thought of, for preventing the like mistake. It may be useful to remember that the suture has its serrae or in- dentations ; is firmly covered by the pericranium ; is close- and does not bleed : but that a fissure, or fracture of the skull,. runs in one direct line ; is larger and broader at the place of the injury ; grows smaller, as you recede from that, till it vanishes by its smallness ; and that it always bleeds. Indeed the older surgeons, observing this, poured ink upon the sus- pected part, which, if the skull was hurt, sunk into the fissure- and made it black and visible ; but left the suture untouched. They also directed to make the patient take a wire betwixt his teeth, which being struck, like the string of an instrument* he would feel the twang produce a painful and peculiar sensa- tion in the fractured part of the head. But after all these ob- servations, in place of any true and certain marks, we find a number of accidents which may lead us into a mistake. Sutures cannot be distinguished by their serrae or teeth, for the temporal sutures want this common character, and rather resemble capillary fractures of the skull ;* nor even by their places, for we know that there are often insulated bones (ossa Wormiana) surrounded with peculiar joinings, which so de- range the course of the common sutures, that the joinings may be mistaken for fractures of the skull, and the ossa Wormiana for broken parts. Sometimes the squamous su- ture is double, with a large arch of bone intercepted betwixt the true and the false suture ; or the sagittal suture, descend- ing beyond its usual extent, and quite to the nose, has been mistaken for a fracture, and trepanned ; and often in older skulls, the sutures are entirely obliterated, all over the head. * Viz. Fractures as small as a hair, thence named capillary. OF THE SKULL IN GENERAL. 27 If the surgeon should pour ink upon the skull, he would have reason to be ashamed of an experiment so awkward and un- successful ; and for the old contrivance of a wire or cord held in the mouth, it cannot be done, since the patient is commonly insensible; and even, though less hurt, his feelings, after such an accident, must be very confused; he must be too liable to be deceived; and we cannot, on such slender evidence as this, perform so cruel an operation as cutting up the scalp, or so dangerous a one as the trepan. For various reasons we are careful to trace the bones from their original soft and gristly state, to their perfect condition of hard bone; and most of all, we are concerned to do so in the head, where, in childhood, the appearances are not singular and curious only, but have always been supposed to indicate some wise and useful purpose. It is in this original condition of the soft and growing bones, that anatomists have sought to find a theory of the sutures, how they are formed, and for what uses. It has been remarked, that the number of pieces in the skull, is infinitely greater in the child than in the man. These bones ossifying from their centre towards their circum- ference, it happens, of course, that the fibres are close at the centre of ossification, and are more scattered at the extremi- ties of the bone : when these scattered fibres of opposite bones meet, the growing fibres of one bone shoot into the interstices of that which is opposed: the fibres still push onwards, till they are stopped at last, and the perfect suture, or serrated line of union is formed. In dilating this proposition, we should observe, that in the boy, all the bones in the head are membranous and imperfect. The membranous interstices begin to be obliterated ; the su- tures are beginning to close ; the distinction of two tables is not yet established; the cancelli are not yet interposed be- twixt the plates; the sinuses, or caverns of the bones, as in the forehead, the nose, and the jaw are not formed ; and each bone is not only incomplete towards its edges and sutures, but consists often of many parts. The os frontis is formed of two pieces, which meet by a membranous union in the middle of the bone. The ossa parietalia have one great and pro- minent point of ossification in the very centre of each, from which diverging rays of ossification extend towards the edges of the bone. The os occipitis is formed in four distinct pieces ; and the temporal bones are so fairly divided into two, that their parts retain in the adult the distinct names of petrous and squamous bones. Alth6ugh these are all the re- gular points of ossification, yet sometimes there occur small imd distinct points, which form irregular bones, uncertain in 28 OF THE SKULL IN GENERAL. number or size, found chiefly in the lambdoid suture, some> times numerous and small, more commonly they are lew in number, and sometimes of the full size of a crown., always distorting more or less the course of the suture, and being tnus a subject of caution to the surgeon: these are named ossa triquetra, or, triangularia, from their angular shape, or, wormiana, from Olaus Wormius, who observed them first. Now the os frontis being formed in two larger V™™> their edges meet early in life, and they form a suture ; but the bones continuing to grow, their opposite points force deeper and deeper into each other, till at last the suture is entirely ob- literated, and the bones unite ; and so this suture is found always in the child, seldom in the adult, almost never in old age. The occipital bone having four points, they are closer upon each other, they meet early, are soon united; and, al- though very distinct in the child, no middle suture has ever been found in the adult, but always the four pieces are united into one firm and perfect bone. The parietal bones have their rays most of all scattered ; the rays of ossification run out to a great distance, and diverge from one single point, so that at their edges they are extremely loose, and they never fail to form sutures, by admitting into their interstices the points and edges of the adjoining bones. The surest and most constant sutures are those formed by the edges of the parietal bones ; the sagittal in the middle, the coronal over the forehead, the lambdoidal behind, and the squamous suture, formed by their lower edges. But another phenomenon results at the same time, from this meeting and opposition of the fibres and in- terstices of the growing bones : that when the opposite fibres meet too early, they are not fairly admitted into the open spaces of the opposite bone : but the fibres of each bone being directly opposed point to point, they both turn inwards, and form a ridge or spine, such as is seen on the inner surfaces of the frontal and occipital bones. Such is the common theorv, which I suspect is imperfect, and which should be received with some reserve, for all the phenomena are not yet explain- ed ; we find each suture always in its appointed place : we find nothing like a suture formed betwixt the head and body of a long bone, though they are formed in distinct points, and are not united till after the years of manhood ; we find no sutures when bones are broken and reunited; when they have been spoiled, and are replaced ; when a piece of spoiled bone has been cut away ; or when a new shaft of a bone is formed by the secreting vessels, and is united to the heads of the old bone. These are accidents which hold us at least in doubt. It has been supposed, and with much appearance of truth. 0» THE SKULL IN GENERAL. 29 that the sutures limit the extent of fractures ; leave a free com- munication of the internal with the external parts ; that they must serve as drains from the brain ; that they are even capa- ble of opening at times, so as to give relief and ease in the most dreadful diseases of the head. But I fear we are not yet able to see the meaning of this peculiarity of structure ; for the sutures are regular and uniform to a wonderful degree, while these uses of them are far from being proved. The sutures surely were not intended by nature for limiting the extent of fractures: for fractures traverse the skull in all directions ; cross the sutures with ease; and very often passing all the sutures, descend quite to the basis of the skull, where we dare not follow them with the knife, nor apply the trepan. Indeed we do not even know that limiting the extent of frac- tures could be a gracious provision of nature, since it would rather appear by the common accidents, that the more easily the bone yields, the less is the injury to the brain; and that where the fracture is wide and large, the symptoms are mild- er, and the danger less. Neither were they intended as drains ; for surely it is a bold position to assume, that nature has carefully provided for our making issues upon the sutures. When the original openness of the head and the membranous condition of the sutures was first observed, it was thought to be an observation of no small importance. The ancients believed that the membranes of the brain came out by the sutures, to form the pericranium, and going from that over the several joints, formed the peri- osteum for all the bones. They saw a close connexion betwixt the external and internal membranes of the skull; and they thought that nature had intended there a freer communication, and an occasional drain. They found the sutures particularly wide and membranous in a child, which they attributed to the watery state of its brain, requiring a freer oudet than in the adult; and accordingly they named the opening of the child's head the bregma, fons, fontanelle, the fountain, by which they believed there was a continual exudation of mois- ture from the brain. We might have expected these notions to have vanished with the doctrines of humours and revulsion which gave rise to them ; but both the doctrines, and the practice, have been revived of late years ; and a surgeon of some eminence has been at pains to examine various skulls, trying to find which of all the sutures remains longest open, and which should form the readiest and surest drain; and after a curious examination of each, he decidedly condemns the fontanelle ; finds the ad- ditamentum of the squamous suture always open, and expects 30 OF THE SKULL IN GENERAL. this superior advantage from placing his issues there, that he ■will command at once a drain both from the cerebellum and from the brain. But these notions, so much cherished by the ancients, of derivation and revulsion, of serous humours fall- ing upon the brain, of drains of pituita by the nose and through the sutures, have been long forgotten, and have not been effectually revived by this attempt. It cannot be denied, that, in some instances, the sutures have continued quite open in persons grown in years, or have opened after a most wonderful manner, in some diseases of the head. A young man having been brought into an hospital ill of a fever, the physicians observing with surprise a very strong pulsation behind the ear: upon applying the finger, a strong beating was felt; the part was soft and yielding; and upon opening his head, after death, there was found a large mem- branous space. Diemorbrock found the fontanelle open in a woman of forty years of age. Bauhin says, that in his own wife, twenty-six years of age, the sutures were not yet closed. This fontanelle, or opening at the meeting of the coronal and sagittal sutures, was once thought to be a sure mark for the accoucheur to judge by, both of the life of the child, and of the direction in which its head presented. It is large and soft in a child ; and the good women lay a piece of firm cloth upon it, and defend it with particular care. It begins to con- tract from the time of birth ; and in the second and third year, it is entirely closed. Its closing is delayed by weakness, scro- fulous complaints, and indeed by any lingering disease ; it closes very late in rickets ; and in hydrocephalic children the bones never close, but continue soft, yield to the watery swel- ling of the brain, and separate in a wonderful degree, so as to hold ten or twelve pounds. As the sutures continue open in a hydrocephalic child, they are said to open again in the few instances where adults are seized with the same disease. We are told that it opens in those dreadful headaches which are sometimes fatal, and that the celebrated Paschal having died after terrible torments, was found to have the sutures opened again. It is even said that they open during disease, and close after the cure : " That a " man of forty years of age being in the dog-days seized with " a raging fever, delirium, watching, and dreadful pains of " the head, his sutures, opened on the seventh day, were as " wide as in a child ; not only so as to be distinguished by the *' finger, but that the attendants could see the pulsations of the " brain : the fever, after some time, abated ; the pains ceas- ft ed ; the sutures closed, and this man lived many years in OF THE SKULL IN GENERAL. 3Y " perfect health." So Hildanus reports the case ; and he also says, in another instance, that the sutures had parted in a vio- lent hemicrania, with an audible noise. Yet, if this were a regular design of nature, the relief should be perfect; perhaps the opening of the sutures should be more easy, and die accident almost as common as diseases of the head: or perhaps it had been the more merciful order, to have determined a quick and sudden period for such dread- ful and incurable diseases as these. The sutures of the cranium are accidental merely, and of little use. The result, perhaps, of this well known law, that nature seeks to facilitate ossification, by beginning the process in many points ; and she establishes as many distinct points, in healing a broken limb as in forming the skull. But however they may be formed, their uses cannot be of that importance which has been supposed ; for there are twenty separate bones, and twenty sutures in the face, where they can neither stop fractures, nor serve as drains, nor open so as to give relief. But if the sutures of the cranium have any thing peculiar and different from those of the face, in that, perhaps, their peculiar uses may be found. We cannot pass unnoticed their looseness and flexibility in the new-born child ; how wonder- fully the head of the child is increased in length, and reduced in breadth in the time of delivery, and how much this con- duces to an easy and happy labour. The most eminent anatomists have condescended to remark, that in the various nations of Europe the head has various forms ; which they ascribe to so slight a pressure as that which dress, or even the posture of the head, might produce- But how very far Vesalius was deceived in calculating thus, is easily proved. The Turks, says he, have their heads flat- tened by wearing the turban. But the turban is an eastern dress : the Turks or Tartars are a northern people, who as- sume this dress only when conquest brings them into a warm- er climate ; and the prominent cheek-bones, parted eyes, and flat heads, continue in the Tartars, who have but newly as- sumed the turban, while the conquered nations who have worn it long, are distinguished by their regular and beautiful features. Perhaps by contrivance and force, we may distort the head of a child ; and we may almost believe what is told of the negroes of the Caribbee islands, who had contrived, by pressure, to flatten their children's heads, that their race might be in future distinguished from those who had submit- ted to the Spanish yoke ; or of what is told so often of eastern nations, that they sometimes mould the heads of children into monstrous and uncouth forms, to extort charity, or as an act DESCRIPTION OF THE of religion. Were I to assign a reason for the flexible bonesy and wide suWs, and the yielding condition of the head ot the child, I should say that it were meant by nature to stand in the place of that separation of the bones of the pelvis which has been supposed, but which cannot exist; for the child s head is moulded with little injury, is evolved again without help ; and it seems a provision of nature, since the child scarcely feels the change : but no woman has been known to have the joinings of the pelvis relaxed or dissolved without pain and danger, confinement for many months, a temporary lameness ; and sometimes she is rendered unable for life. CHAP. III. DESCRIPTION OF THE INDIVIDUAL BONES OF THE SKULL. Us FRONTIS. This bone is compared with a clamshell. It is of a semicircular shape, hollowed like a shell, and very equal in its thickness. It is marked on the inside by a spine, or prominent line, which divides the hollow of the bone into two equal parts, and gives rise to a membranous partition, which divides and supports the hemispheres of the brain. It is marked on its external surface by those high ridges on which the eyebrows are placed ; and by two prominences, un- der which are hollow caverns, named the sinuses (or cavities) of the frontal bone. It is irregular only in its orbitarv plates, which are the two thin and delicate lamellae that depart from the general direction of the bone, and stand out horizontally so as to form a part of the socket for the eye, or, as it were, a roof defending the upper part of the eye, and a floor for sup- porting the lower part of the brain ; and these two orbitary plates leave an open space, in which is incased the chief part of the aethmoid bone. The first point to be remarked, is the superciliary ridge, on which the eyebrows are placed : it is a prominent arched line, corresponding in size and length with the eyebrow which it supports. It is the origin of the frontal muscles. In this line, the integuments adhere very strongly, by many arteries which perforate the bone, and which are properly the nutriti- ous arteries of this part of the bone ; and we find all over the superciliary ridge many small holes through which these ar- INDIVIDUAL BONES OF THE SKULL. 3$ teries had passed. Among these, there is one hole which is larger, and which is distinguished from the rest ; tor its use is not like the others to transmit arteries to the bone, but to give passage to a small artery which comes out from the or- bit, to mount over the forehead. Sometimes this artery turns freely over the border of the orbit, and makes no mark, or but a slight one : often lying closer upon the bone, it forms a notch ; but most commonly, in place of turning fairly over the edge of the orbit, it passes obliquely through the superciliary ridge, and, by perforating the bone, makes a hole. This hole is named the superciliary hole. The artery which comes from the eye to go out upon the forehead is named, where it passes the ridge, the superciliary artery ; and higher up upon the forehead, the frontal artery. It establishes a communica- tion betwixt the internal arteries of the eye, and the external arteries of the forehead and temple ; and it carries along with it a small nerve from the eye, which, going also out upon the forehead, is named the superciliary or frontal nerve. We are always warned of the danger of wounding arteries where they pass through bones ; and strange stories are told of the terrible bleedings which have arisen from this artery when wounded near its hole ; and of the convulsions, palsies, and loss of sight, which have arisen from the accidents, wounds, or lacerations of this frontal nerve : these stories are delivered on authorities which we dare not refuse, and yet they are such as we cannot easily believe. This orbitary, or superciliary ridge, ends by two processes, which, forming the angles of the eye, are named the angular processes. The frontal bone has therefore four angular pro- cesses: 1. The two internal angular processes, forming the internal angles of the eyes y and, 2. The two external angular processes which form the external angles of each eye. Behind each external angular process, the bone lies flat, and sunk into a hollow which lodges the temporal muscles ; and betwixt the two internal angular processes there is the nasal point or process. This nasal process is a small sharp projecting point, which is exactly in the middle of the bone, occupying that space which is betwixt the two internal angular processes. It is very irregular and rough all round its root, for supporting the two small nasal bones; and this gives them a firm seat, and such a hold upon the root of the forehead, that they will be sooner broken dian displaced. At the inner end of the superciliary ridge, is that bump which marks the place of the frontal sinuses : it also in some degree indicates their size ; for where this rising is not found, the sinuses are wanting, or are verv small, but this is no sure, Vol. I. F. 34 description of the J nor absolute mark of the presence of these sinuses, which often, in the flattest foreheads, are not entirely wanting. The sinuses* of the os frontis are two in number, one on either side above the root of the nose : they are formed by a receding of the two tables of the skull from each other : they are formed at first with the common cancelli, and at first they resemble the common cancelli, as if they were only larger cells : gradually they enlarge into two distinct cavities, often of very considerable size ; going down into the orbitary plate, or sidewise into the orbitary ridge, or upwards through one half of the frontal bone ; and Ruisch had, in a giantess (puella gigantica), seen them pass the coronal suture, and extend some way into the parietal bones. The sinuses of either side are separated by a partition; but still they communicate by a small hole: sometimes the partition is almost wanting, and there are only crossings of the common lamellated substance ; and though the communication with one another is not always found, they never fail to com- municate with the nose. This indeed seems to be their chief use ; for the frontal sinuses are the beginning of a great train of cells, which, commencing thus in the frontal bone, extend through the aethmoidal, sphenoidal, and maxillary bones, so as to form an organ of great extent and use belonging to the nose; but perhaps not so much for extending the organ of smelling, as for making a more sonorous voice. For we have no proof that the sinuses are part of the organ of smell ; un- less we should accept of this as a proof, that by the smelling of strong volatiles, pain shoots upwards into the forehead; though, by this rule, the eyes should be also a part of the same organ, since, from the same cause, they are pained, and tears begin to flow: but we do know that the sinuses belong to the voice, and raise its tone, for we feel the trembling note re- sound through all these cells ; so that the voice is sonorous while they are free ; is damped when the sinuses are oppressed by their membranes being thickened by cold ; or is almost sup- pressed when the sinuses are entirely closed ; or when, by venereal ulcers, the curtain of the palate is consumed, no part of the voice passing upwards into the nose, it is almost lost. This has given rise to a very common mistake : that as these sinuses are wanting in the child whose forehead is flat, as * The word Sinus is used in two senses: we call the cavities or cells within the substance of a bone, the sinufes of that bone; as the sinuses of the forehead of the sphenoid, asthmoid, or maxillary bones: we call also certain great veins by'the same name of sinuses. Thus the great veins being enlarged where they approach the heart, and the veins being particularly large in the brain and the womb, we call them the sinuses of the heart, of the brain, and of the womb. INDIVIDUAL BONES OF THE SKULL. 3.5 they enlarge gradually, and are fully formed about the fifteendi year, the vox rauca, the breaking of the voice, which is ob- served about that time, must be owing to the evolution of these cells. But the female voice does not undergo the same change by the evolution of these cells ; and castration, which surely can have no effect on these cavities, keeps down the eunuch's to the treble key of the female voice. The mistake lies in supposing these cavities to raise the tone or note in which we speak, while they only add clearness and strength. The mem- brane which lines these cavities is thin, and exquisitely sensi- ble, and is a continuation of the common membrane of the throat and nose. A thin humour is poured out upon its sur- face to moisten it and keep it right. This the ancients did not consider as merely a lubricating fluid, but as a purgation of the brain, drawn from the pituitary gland; which could not be diminished without danger, and which it was often of consequence to promote. These sinuses are subject to one accident chiefly, viz. in- sects, which nestle there, and produce inconceivable distress ; and it is particular, that insects more frequently lodge in the frontal sinuses, than in the cavities of any of the other bones. In sheep and dogs, such insects are very frequent, as, in seek- ing their food, they carry their nose upon the ground ; and it has been proved, or almost proved, that in man they arise from a like cause. Indeed what can we suppose, but that they get there by chance ? Thus, a man having slept in barns, was afflicted with dreadful disorders in the forehead, which were relieved upon discharging from the nose a worm of that kind which is peculiar to spoiling corn ; while others have had the complaint, by sleeping upon the grass. But there is something very particular in this, that by far the greater num- ber of these worms have been of the centipede kind; generally long, an inch in length, with one hundred, or, according to Linnaeus, one hundred and twelve feet, and not unfrequendy covered with hair. There are reports which seem to prove, that some have died of this complaint, and in a very misera- ble way. In many cases it has been attended with delirium ; and in almost every instance it has continued for years. No wonder, then, that the trepanning of these sinuses has been often proposed ; but I have never read of a well marked case, so that we could be assured beforehand of finding worms : they have, in most cases, been discovered rather by chance. The patient might be relieved on easier terms, by the injec- tion of aloes, assafoetida, mvrrh, the use of snuff or smoak- ing, and pressing the fumes upwards into the nose. ' Much 3& DESCRIPTION* OF THE should be tried, before undertaking a dangerous operation or* such slender proofs. . . It may be right, in cases of fractures, to decline applying the trepan above the sinuses, unless a fracture cannot be rais- ed in any easier way ; and we must be, especially, careful ta distinguish a fracture of the outer table only, from entire frac- tures of this bone. For Palfin says, that the outer table be- ing broken, and the natural mucus of the sinus being corrupt- ed and flowing out, has been mistaken for the substance of the brain itself. And Paree, who first gives this caution, affirms, " that he had seen surgeons guilty of this mistake, " applying the trepan, and so killing their unhappy patients. The spine or ridge which runs upon the internal surface of the frontal bone, is to be observed, as it gives a firm hold; to the falx, or that perpendicular membrane, which, running in the middle of the head, divides and supports the brain. This is more or less prominent in different skulls, and accord- ing to the age. The spine is more prominent at its root; but as it advances up the forehead, it decreases, and often ends in a groove. The spine gives firm hold for the falx, and the groove lodges the great longitudinal sinus, or, in other words, the great vein of the brain, which runs along the head, in the course of the perpendicular partition or falx. At the root of; this spine, there is a small blind hole, which will just admit a pin ; it is named blind, because it does not pass quite through the bone, and the beginning of the falx, dipping down into this hole, gets a firmer hold. The ancients thinking that this hole descended through both tables into the nose, believed, that the dangerous and ungovernable bleedings at the nose^ must be through this hole, and from the fore end, or begin- ning of the longitudinal sinus. The orbitary process is the last remarkable point of the frontal bone. The orbitary processes are two thin plates, de- parting from the general direction of the bone, and standing inwards at right angles: they cover the eye, and support the brain. By the continual rolling of the eye, and the pressure of the brain, they are extremely thin and transparent; the rolling of the eye makes them exquisitely smooth below, and on their upper surfaces they are impressed with the frequent convolutions of the brain : so that a wound through the eye endangers more than the eye ; for it passes easily forward in- to the brain, and is instandy fatal: it is the aim of a fencer • and we have known, in this country, a young man killed by the push of a foil which had lost its guard. Upon the orbitary plate, and just under the superciliary ridge, there are two depressions in the socket of each eye : INDIVIDUAL BONES OF THE SKULL. 37 the one is very small* and deeper at the inner corner of the eye, under the orbitary hole, which is the mark of the small cartilaginous pulley, in which the tendon of one of the mus- cles of the eye plays ; the other, a more gentile and diffused hollow, lies under the external angular process, is not deep* but is wide enough to receive the point of a finger, and is the place where the lachrymal gland lies; that gland which se- cretes the tears, and keeps the eye moist. OSSA PARIETALIA__The parietal bones form by much the greater share of the cranium: they are more exposed than any others ; they are the most frequendy broken, and the most easily trepanned ; for the parietal bones are more uni- form in their thickness, and more regular in their two tables and diploe, than any others* But the accidental varieties of pits and depressions are very frequent in them;., and the sinus or great vein, and the artery which belongs to the membranes of the brain, both make their chief impressions upon this bone. Each parietal bone is very nearly of a square form, sur- rounded by deeply serrated edges, which unite them with each other, and with the occipital and frontal bones. All die corners of this bone are obtuse, except that one which lies in me temple, and which, running out to a greater length than the other corners, is sometimes named the spinous process of the parietal bone ; though there can be no true process in a bone so regular and flat. The lower edge of the bone is a neat concave semicircle, which joins the parietal to the tem- poral bone ; and the edge of each is so slanted off, that the edge of the temporal overlaps the edge of the parietal, with a thin scale, forming the squamous suture. About an inch above the squamous suture, there is a semicircular ridge, where the bone is particularly white and hard; and rays extend downwards from this, converging towards Wrawls die jugum, or arch of the temple. The white semicircular line represents the origin of the temporal muscle; and the converging lines express the manner in which th# fibres of the muscle are gath- ered into a smaller compass, to pass under the jugum. The sagittal suture, or meeting of the two parietals, is marked on the inside with a groove as big as the finger, which holds the longitudinal 6inus, or great vein of the brain : but the groove is not so distinctly seen, unless the two bones be put together ; for one half of this flat groove belongs to each bone. The great artery of the dura mater touches this bone at that angle of it which lies in the temple. It traverses the bone from comer to corner, spreading from the first point, like the 38 description of the branches of a tree, it beats deep into the bone where it first touches it; but where it expands into branches, its impres- sions are very slight; commonly it makes a groove only, but sometimes it is entirely buried in the bone; so that at the lower corner of the parietal bone we cannot escape cutting this vessel, if we are forced to operate with the trepan. There is but one hole in the parietal bone : it is small and round, is within one inch of die meeting of the lambdoidal and sagittal sutures, and gives passage to a small external vein, which goes inwards to the sinus ; and to a small artery which goes also inwards to the dura mater, or rather to the falx. The meeting of the frontal and parietal bones, being imper- fect in the child, leaves that membranous interstice, which by some is named folium or folliolum, from its resembling a tre- foil leaf; and was named by the ancients hypothetically, bregma, fons,* or fountain ; they thinking it a drain of mois- ture from the brain j and so the parietal bones are named ossa bregmatis. OS OCCIPITIS.—This bone has also the names of os me- moriae, and os nervosum. It is the thickest of the cranial bones, but is the least regular in its thickness, being transpa- rent in some places, and in others swelling into ridges of very firm bone. It gives origin or insertion to many of the greatest muscles, which move the head and neck ; it supports the back part of the brarh ; contains the cerebellum or lesser brain ; transmits the spinal marrow, and is marked with the conflux of the chief sinuses, or great veins of the brain. The external surface is exceedingly irregular, by the impressions of the great muscles of the neck : for first the trapezius and complexus, two great external muscles of the neck and head, have their chief hold upon the occipital bone, by which there is formed one great transverse spine. Be- low these again, the recti muscles, two small and deep muscles of the head and neck, make another transverse spine below the first: so that there is a double transverse spine ; and the interstice betwixt the muscles of the opposite sides leaves of course, a prominent ridge or spine, which, running from above downwards, crosses the first ridges, and makes a cross called the crucial spine ; and in a strong man advanced in years, where the ridges and hollows are strongly marked the » The word pulsatilis, or fons pulsatilis, or beaming fountain, was added be- cause we feel the beating of the arteries of the brain there. INDIVIDUAL bones of the skull. 39 point where these ridges cross, is so very prominent, as to be named the posterior tuberosity of the occipital bone. The internal surface. Opposite to these ridges, there are similar crucial ridges within ; but more regular, smooth, and equal, and making only one transverse line. The tento- rium cerebello-super-extensum, is a diaphragm or trans- verse partition, which crosses the skull at its back part; cuts off from the rest of the cranium the hollow of the occipital bone ; appropriates that cavity for the cerebellum, and de- fends the cerebellum from the weight and'pressure of the brain. This tentorium, or transverse membrane, is attached to the great internal ridge of the occipital bone. In the angle where this membrane is fixed to the ridge, lies the great sinus or vein ; which is called longitudinal sinus, while it is running along the head ; but the same sinus, dividing in the back of the head, into two great branches, changes its name with its direction ; and the forkings of the vessel are named the right and left lateral sinuses, which go down through the basis of the skull; and being continued down the neck, are there named the great or internal jugular veins. This fork- ing of the longitudinal^ into the lateral sinuses, makes a tri- angular or tripod-like grooveV which follows the inter- nal ridges of the occipital bone : and above and below the transverse ridge, there are formed four plain and smooth hol- lows. The two upper ones are above the tentorium, and con- tain the backmost lobes of the brain ; • thte tyfi>}®Wer ones are under the tentorium, and hold, the lobes o#' fciijjf^cerebellum or little brain. - f Processes. The processes or projections of the occipital bone are few and simple. 1. There is apart of the bone which runs forward from the place of the foramen magnum ; lies in the very centre of the base of the skull; and joins the occipital to the sphenoidal bone ; and which, both on account of its place (wedged in the basis of the skull,) and of its shape, which is rather small, and somewhat of the form of a wedge, is named the cuneiform, or wedge-like process of the occipital bone. And, 2. There are two small oval processes, or button-like projections, which stand off from the side, or rather from the forepart of the foramen magnum, or great hole, and which, being lodged in joints belonging to the upper bone of the neck, form the hinge on which the head moves. These two processes are named the condyles of the occipital bone. They are not very prominent, but rather flat- tened ; are of an oval form, and have their fore-ends turned a little towards each other ; so that by this joint the head moves directly backwards or forwards, but cannot turn or roll. The 40 description op the turning motions are performed chiefly by the first bones of the neck. Round the root of each condyle, there is a roughness, which shows where the ligament ties this small point to the corresponding bone of the neck. Holes.—1. These condyles stand just on the edge of the foramen magnum, or great hole of the head, which trans- mits the spinal marrow, or continuation of the brain ; and the edges of this hole (which is almost a regular circle) are turned and smoothed ; a little thicker at the lip, and having a rough- ness behind that, giving a firm hold to a ligament, which, de- parting from this hole, goes down through the whole cavity of the spine, forming at once a sheath for the spinal marrow, and a ligament for each individual bone. There passes down through this great hole the spinal marrow, and die vertebral vein. There come up through it the vertebral arteries, which are of great importance and size ; and a small nerve, which, from its coming backwards from the spine to assist certain nerves of the brain, is named the spinal accessary nerve. 2. The second hole is placed a little behind the ring of the foramen magnum, and just at the root of either condyle, is round, and large, easily found, and sometimes it is double; it transmits the ninth pair, or great lingual nerve. 3. There is another hole smaller, and less regular than this last. It is exactly behind the condyle, while the lingual hole is before it. It is for permitting a small vein, the cervical vein of the neck, to enter and drop its blood into the great lateral sinus ; but often it is not formed, and this trifling vein gets in by the great occipital hole. 4. We shall describe with the temporal bone that wide hole which is common to the temporal and occipital bones, and which transmits the great lateral sinus. OS TEMPORIS.—The temporal bone is, in the child, two bones ; which retain their original names of pars petrosa and pars squamosa. The whole bone is very irregular in its thickness, and hollows, and processes. The pars sqjjamosa is a thin or scaly part; rises like a shell over the lower part of the parietal bone, and is smoothed and flattened by the rubbing of the temporal muscle. The pars petrosa, often named os lapidosum, or stony bone, is hard, irregular, rocky; juts inward towards the basis of the skull; contains the organ of hearing, and, of course, receives and transmits all the nerves which are connected with the ear. There is a third portion of this bone, viz. the occipital angle, which is thick and hard; is divided into cells, and forms those caverns which are supposed to be chiefly useful in reverberating the sound. individual bones of the skull. 41 The squamous part is grooved, to make the squamous su- ture ; is scolloped or fringed; and exceedingly thin on its edge ; it is radiated, in consequence of its original ossification shooting out in rays. The petrous part again is triangular, unequal by the cavities of the ear ; it has a very hard, shining, polished-like surface ; exceeded in hardness by nothing but the enamel of the teeth. Where it projects into the base, it has several open points, which are filled up with cartilaginous or ligamentous substance ; and its occipital angle is connected with the other bones by the additamentum suturae squamosa?. Processes. 1. The zygomatic process rises broad and flat before the ear ; grows gradually smaller as it stretches forward to reach the cheek bone : forms with a process of that bone the zygoma, yoke, or arch of the temple, under which the temporal muscle plays. The temporal muscle is strength- ened by a firm covering of tendon, which stretches from the upper edge of this zygoma to the white line on the parietal bone ; and several muscles of the face arise from the lower edge of the zygoma, particularly one named massiter, which moves the jaw ; and one named zygomaticus, or distortor oris, because it draws the angle of the mouth. The zygomatic process is united by a short suture to the cheek-bone. 2. The styloid process, is so named from a slight resem- blance to the stylus, or point with which the ancients engraved their writings on tables of wax. It is cartilaginous long after birth ; even in the adult, it is not completely formed ; it is ex- ceedingly delicate and small; and when its cartilaginous point is fairly ossified, as in old men, it is sometimes two inches long. It stands obliquely out from the basis of the head, and is behind the jaw ; so that it gives convenient origin to a liga- ment which goes downwards to support the os hyoides, or bone of the tongue; and it is the origin of many curious muscles, chiefly of the throat and jaws. One slender muscle going downwards from the styloid process, and expanding over the pharynx, is called stylo-pharingeus ; one going to the os hyoides, is the stylo-hyoideus ; one going to the tongue, is the stylo-glossus ; and since the process is above and behind these parts, the muscles must all pull backwards and upwards, raising according to their insertions, one the pharynx, another the os hyoides, another the tongue. 3. The vaginal process will not be easily found, nor acknowledged as a process ; for it is only a small rising of a ridge of the bone, with a rough and broken-like edge, on the middle of wrhich the styloid process stands : it is, in short, the root of the styloid process ; and anatomists have chosen to ob- serve it, though it gives origin to no particular part; and they Vol. I. F 42 description of the have named it vaginalis, as if it resembled a sheath for the styloid process. . . - 4. The mastoid or mammillary process, is a conical nipple-like bump, like the point of the thumb ; it projects from under the ear, and is easily felt with the finger without; it is hollow, with many cells which enlarge the tympanum, or first cavity of the ear, and are thought to reverberate and strengthen the sound. Under its root, there is a deep and rough rut which gives a firm hold to the first belly of the digastric mus- cle ; and the point or nipple of this process is the point into which the mastoid muscle is inserted from before, and the complexus, obliquus, and trachelo-mastoidseus muscles from behind. It has been proposed of late years, that, in certain cases of deafness, we should open this part with the trepan. 5. The auditory process is just the outer margin of the hole of the ear. It is in a child a distinct ring, which is laid upon the rest of the bone. The membrane of the ear is ex- tended upon this ring, like the head of a tambour upon its hoop, whence this is named the circle of the tambour by the French, and by us the drum of the ear. In the adult this ring is fairly united to the bone, and is named the processus auditorius ; and may be defined a circle, or ring of bone, with a rough irregular edge ; the drum or membrane of the ear is extended upon it, and the cartilaginous tube of the ear is fixed to it; and this ring occupies the space from the root of the mammillary to the root of the zygomatic process. Holes. The temporal bone is perforated with many holes, each of which relates to the organ of hearing; some for per- mitting nerves to enter; others for letting them out; and others for the free passage of air to the internal ear. 1. The meatus auditorius externus (the circle of which has been described), is covered with the membrane of the drum, and communicates the vibratory motion of the air for moving and exciting the internal organs. 2. The meatus auditorius internus, is that hole by which the auditory nerves have access to the ear. It is a very large hole, seated upon the back of the pars petrosa, which is of a triangular form. The hole is at first large, smooth, almost a regular circle, with a sort of round lip. Within this there are seen many small holes, the meaning of which is this : the audi- tory nerve is double from its very origin in the brain : it con- sists, in fact, of two distinct nerves, the portio dura, and the portio mollis. The portio mollis is a large soft and delicate nerve, which constitutes the true organ of hearing ; and when it is admitted into the ear, it is expanded into a thin web which spreads over all the cavities of the ear, as the cochlaea, semi- individual bones or the skull. 43 circular canals, &c. The portio dura, the smaller part of the nerve, passes indeed through the ear, but it is quite a foreign nerve ; it is not distributed within the ear ; it keeps the form of a distinct cord, and passing through the temporal bone, it comes out upon the cheek, where it is expanded ; so that the portio dura is a nerve of #the face, passing through the ear, but forming no part of that organ. Thus the two nerves, the portio dura and the portiojnollis, enter together ; they fill the greater hole, and then they part; the portio dura, entering by one distinct hole, takes its course along a distinct canal, the aque- duct of Fallopius, from which it comes out upon the cheek; while the portio mollis entering by many smaller holes into the cochlaea, semicircular canals, and other internal parts of the ear, is expanded in these cavities to form the proper organ of hearing. 3. There is upon the fore part of the petrous bone a small hole which will admit the point of a pin. This hole receives a small twig reflected from the fifth pair of nerves : the nerve is as small as a sewing thread; it can be traced along the petrous bone by a small groove which conducts it to the hole ; and when it enters the ear, it goes into the same canal with the portio dura, and joins itself to it. 4. The hole by which the portio dura passes out upon the cheek, is found just before the mastoid, and behind the styloid process ; and being betwixt the two, it is named the stylo- mastoid hole, and is so small, as just to admit a pin. 5. The hole for the Eustachian tube is very irregular. No air can pass through the membrane of the drum ; and as air is necessary within the ear, it is conveyed upwards from the pa- late by the iter a palato ad aurem, or as it is commonly called, the Eustachian tube. This tube is long, and of a trumpet form ; its mouth, by which it opens behind the nostril, is wide enough to receive the point of the finger; it grows gra- dually smaller as it advances towards the ear ; it is cartilagin- ous in almost its whole length ; very little of it consists of firm bone ; so that the student, in examining the skull, will hardly find the Eustachian tube ; for the cartilage being rotten away, nothing is left but that end of the canal that is next the ear, and which is open both above and below, ragged, irregular, and broken. When we have a sore throat, the pain extends up along this tube into the ear ; when we have a cold, both our voice and our hearing is hurt ; the one by the stuffing of the sinuses, the Other by the stuffing of the Eustachian tube. When we shut the nose and mouth, and blow strongly, we feel a crackling in the car, as in the place of the Eustachian tube ; when we dive, 44 description of the we feel the same, by the condensation of the air : and some- times by forcing the air strongly upwards through the ear, or by vomits, obstruction of the Eustachian tube, and the deal- ness which attends that accident, are very suddenly, and we may say, violently removed ; or sometimes the cure is attempt- ed by syringing, or by cleaning the mouth of this tube with a probe, just as we do the external ear. The other holes do not relate to the ear, and are chiefly tor transmitting the great blood-vessels of the brain. 1. The carotid artery, the chief artery of the brain, enters into the skull near the point of the petrous bone, and just before the root of the styloid process. The artery goes first directly upwards, then obliquely forwards through the bone, and then again upwards, to emerge upon the inside of the skull; so that the carotid makes the form of an Italic S, when it is passing through the substance of the bone ; and in place of a mere hole, we find a sort of short canal, wide, a lit- tle crooked, and very smooth within. There seems to be a particular design in this angle, which the artery is forced to make : perhaps it is designed to abate the violence with which the blood would drive forwards into the brain ; for in many of the lower animals, there are still more particular provisions than this, the artery being prevented from entering the brain in one great trunk, by a curious division, into many branches, which meet again. It is at this particular point that we are sensible in our own body of the beating of these two great arte- ries ; and Haller is at pains to inform us, that, during a fever, he felt this beating in a very distressing degree. 2. The great lateral sinus comes out through the tem- poral bone, to form the internal jugular vein. The course of the sinus may be easily traced by the groove of the occipital bone downwards, behind the pars petrosa : there also it makes a deep groove, and ends with a large intestine-like turn, which makes a large cavity in the temporal bone, big enough to re- ceive the point of the finger. The sinus passes out, not by any particular hole in the temporal bone, but by what is called a common hole, viz. formed one half by the temporal, and one halt by the occipital bone. This hole is very large ; is lace- rated or ragged-like. It is sometimes divided into two open- ings, by a small point, or spine of bone. The larger opening on one side of that point transmits the great sinus, where it begins to form the jugular vein ; and the smaller opening transmits the eighth nerve of the skull, or par vagum which goes down towards die stomach, along with the jugular vein. There is a small furrow upon the very angle or ridge of the petrous bone, which is made by a small vein of the brain goinjr towards the end of the lateral sinus. individual bones of the skull. 45 3. There is a small hole on the outside of this bone in the occipital angle ; or rather the hole is oftener found in the line of the suture (the additamentum suturae squamosa?.) Some- times it is in the occipital bone ; or sometimes it is wanting: it transmits a trifling vein from without, into the great sinus, or a small artery going to the dura mater. That hollow under the root of the zygomatic process, which lodges the hinge of the jaw-bone, must be described along with the lower jaw. The -ETHMOID BONE—This is perhaps one of the most curious bones of the human body. It appears almost a cube, not of solid bone, but exceedingly light, spongy, and consisting of many convoluted plates, which form,-a net-work like honey-comb. It is curiously inclosed in the os frontis, betwixt the orbitary processes of that bone. One horizontal plate receives the olfactory nerves, which perforate that plate with such a number of small holes, that it resembles a sieve ; whence the bone is named cribriform, or aethmoid bone. Other plates dropping perpendicularly from this one, receive the divided nerves, and give them an opportunity of expand- ing into the organ of smelling ; and these bones, upon which the olfactory nerves are spread out, are so much convoluted, as to extend the surface of this sense very greatly, and are named spongy bones. Another flat plate lies in the orbit of the eye ; and being very smooth -by-the relli*»g-e£trre-eye, it is named the os planum, or smooth bone. So that the aethmoid bone supports the forepart of the brain, receives the olfactory nerves, forms the organ of smelling, and makes a chief part of the orbit of the eye ; and the spongy bones, and the os planum, are neither of them distinct bones, but parts of this aethmoid bone. The cribriform plate is exceedingly delicate and thin ; lies horizontally over the root of the nose ; and fills up neatly the space betwixt the two orbit,ary plates of the frontal bone. The olfactory nerves, like two small flat lobes, lie out upon this plate, and adhering to it, shoot down like many roots through this bone, so as to perforate it with numerous small holes, as if it had been dotted with the point of a pin, or like a nutmeg grater. This plate is horizontal; but its processes are perpendicu- lar, one above, and three below. 1. The first perpendicular process is what is called crista galli ; a small perpendicular projection, somewhat like a cock's comb, bvit exceedingly smallv standing directly upwards from the middle of the cribriform plate, and dividing that 46 description of the plate into two ; so that one olfactory nerve lies upon each side of the crista galli; and the root of the falx or septum be- twixt the two hemispheres of the brain, begins from this pro- cess. The foramen caecum, or blind hole of the frontal bone, is formed partly by the root of the crista galli, which is very smooth, and sometimes, it is said, hollow or cellular. # 2. Exactly opposite to this, and in the same direction with it, i. e. perpendicular to the aethmoid plate, stands out the nasal plate of the aethmoid bone. It is sometimes called the azygous, or single process of the aethmoid, and forms the beginning of that septum or partition which divides the two nostrils. This process is thin, but firm, and composed of solid bone ; it is commonly inclined a little to one side, so as to make the nostrils of unequal size. The azygous process is united with the vomer, which forms the chief part of the par- tition ; so that the septum, or partition of the nose, consists of this azygous process of the aethmoid bone above, of the vomer below, and of the cartilage in the fore or projecting part of the nose ; but the cartilage rots away, so that whatever is seen of this septum in the skull, must be either of the arth- moid bone or the vomer. 3. Upon either side of the septum, there hangs down a spongy bone, one hanging in each nostril. They are each rolled up like a scroll of parchment: they are very spongy; are covered with a delicate and sensible membrane; and when the olfactory nerves depart from the cribriform plate of the aethmoid bone, they attach themselves to the septum, and to these upper spongy bones, and expand upon them so, that the convolutions of these bones are of material use in expanding the organ of smelling, and detaining the odorous effluvia till the impression be perfect. Their convolutions are more nu- merous in the lower animals, in proportion as they need a more acute sense. They are named spongy, or turbinated bones, from their convolutions, resembling the many folds of a turban. The spongy bones have a great many honey-comb-like cells connected with them, which belong also to the organ of smell, and which are useful perhaps by detaining the effluvia of odo- rous bodies, and also by reverberating the voice. Thus, in a common cold, while the voice is hurt by an affection of these cells, the sense of smelling is almost lost. 4. The orbitary plate of the aethmoid bone is a large surface ; consisting of a very firm plate of bone, of a regular square form ; exceedingly smooth and polished: it forms a great part of the socket for the eye, lying on its inner side. INDIVIDUAL BONES OF THE SKULL. 47 When we see it in the detached bone, we know it to be just the flat side of the aethmoid bone ; but while it is incased in the socket of the eye, we should believe it to be a small square bone ; and from this, and from its smoothness, it has got the distinct name of os planum. 5. The os unguis should also, perhaps, be counted as a part of this bone ; for though the os unguis, when observed in the orbit, seems to be a small detached bone, thin like a scale, and of the size of the finger nail (whence it has its name,) yet in the adult, the os unguis is firmly attached to the aethmoid bone; comes along with it when we separate the pieces of the skull; and when the os unguis is pared off from the aethmoid bone, the cells are exposed. • This os unguis, then, is a small scaly-like plate, in the inner corner of the orbit just over the nose. We find in it that groove which holds the lachrymal sac, and conducts it to the nose ; and it is this thin bone that we perforate in making the new passage into the nose, when there is an obstruction in the natural duct. 6. The cells of the aethmoid bone, which form so import- ant a share of the organ of smell, are arranged in great num- bers, along the spongy bone. They are small neat cells, much like a honey-comb, and regularly arranged in two rows, parted from each other by a thin partition; so that the os planum seems to have one set of cells attached to it, while another regular set of cells belongs in like manner to the spongy bones. The cells are thus twelve in number,* opening into each other, and into the nose. These cells are frequently the seat of venereal ulcers, and the spongy bones are the surface where polypi often sprout up. And from the general connections and forms of the bone, we can easily understand how the venereal ulcer, when deep in the nOse, having got to these cells, cannot be cured, but under- mines all the face ; how the venereal disease, having affected the nose, soon spreads to the eye, and how even the brain itself is not safe. We see the danger of a blow upon the nose, which, by a force upon the septum, or middle partition, may depress the delicate cribriform plate, so as to oppress the brain with all the effects of a fractured skull, and without any opera- tion which can give relief. And we also see much danger in pulling away polypi, which are firmly attached to the upper spongy bone. * The number is commonly twelve, but not regularly so. 48 DESCRIPTION OF THE SPHENOIDAL BONE—The sphenoidal bone com- pletes the cranium, and closes it below. It is named sphe- noid, cuneiform, or wedge-like bone, from its being in- cased in the very basis of the skull; or it is named os multi- forme, from its irregular shape. It is much the shape ot a bat, whence it is often named the pterygoid bone, its tempo- ral processes being like extended wings ; its pterygoid proces- ses like feet; its middle like the body and head of a bat. Its wing-like processes are in the hollow of the temple, forming a part of the squamous suture, and also composing a part of the orbit of the eye : its pterygoid processes hang over the roof of the mouth, forming the back of the nostrils. The body is in the very centre of the skull, and transmits almost all the nerves of the brain ; but still the body bears so small a propor- tion to the bone, that we have not a regular centre to which all the processes can be referred ; so that we are always, in de- scribing this bone, moving forwards from point to point, from one process or hole to the next. PROCESSES.—1. The al^:, or wings, often named temporal processes, rise up in the temple, to form part of the- hollow of the temple ; and these wings of the sphenoid bone meeting the frontal, parietal, and temporal bones, by a thin scaly edge, they make part of the squamous suture, and give a smooth surface for the temporal muscle to play upon. 2. The other side of this same process lqoks towards the socket of the eye, and has a very regular and smooth surface ; it is exactly opposite to the os planum. As the aethmoid bone forms part of the inside of the orbit, the wing of the sphenoid bone forms part of the outside of the orbit; and so the surface turned towards the eye is named the orbitary process of the sphenoid bone. 3. The lower, or back part of this bone runs out into a narrow point, which sinks in under the petrous portion of the temporal bone, and being sharp pointed, it is named the spinous process. It is very remarkable for a small hole which permits the great artery of the dura mater to enter. 4. The point of this spinous process-projects in the form of a very small peak, which will hardly be found by the student. It projects from the basis of the skull just within the condvle of the lower jaw ; and being a small point, like the point of the stilus, or iron pen, it also is named styloid process, and gives rise to a curious muscle of the palate. INDIVIDUAL BONES OF THE SKULL. 49 5. The pterygoid processes * are four in number, two on either side. They are those processes, upon which (with the spinous process) the bone naturally stands, and which, when we compare it with a bat, represent the legs ; one of each side is named external pterygoid ; the other is named the internal pterygoid process. 1. Each external pterygoid process, is thin, flat, and broad, and extends further backwards. Each internal pterygoid process is taller and more slender; not so flat nor broad. It has its end rising higher than the other, and tipped with a small neat hook, named the hook of the pterygoid process. The inner pterygoid processes form the back of the nostrils. The Eustachian tube comes downwards in a wide groove betwixt the two processes, and then turning its wide mouth towards the nostril, it opens just behind the internal process, viz. behind the nostril, and over the back of the pa- late. The hook of the pterygoid process is called the hook of the palate, of which it forms the backmost point. The mus- culus circumflexus vel tensor palati, rising from the mouth of the Eustachian tube, turns with a small tendon round this hook, like a rope over its pulley; and the great muscles of the lower jaw, the only ones for moving it side wise, or for its grinding motions, arise from the pterygoid processes, so as to be named the external and internal pterygoid muscles, accord- ing to the processes from which they arise. 6. The azygous processj, is so named, from its being single, because it is seated in the centre of the bone, so that it can have no fellow. It stands perpendicularly downwards and forwards, over the centre of the nose, and its chief use is to give a firm seat or insertion for the vomer, or bone, which forms the septum. This with the azygous process of the aethmoid bone united, forms the upper and back parts of the septum ; and the vomer, or proper bone of the partition, stands, with a split edge, astride over these two processes, so as to have a very firm seat. 7. The clynoid processes, have, like many parts of the human body, a very whimsical name, very ill suited to ex- press their form; for it is not easy, in this instance, to ac- * There is some confusion in this name, since pterygoid signifies aliform, or wing-like processes. + Azygous is a term, which is applied to such parts as have no fellow; because almost always the parts on one side of the body are balanced by similar and cor- responding parts on the other side. When they stand in the centre of the body, or are otherwise single, we call them azygous; and so the azygous process of the aethmoid and sphenoid, and other bones; or the azygnu* vein, which runs in the centre of the thorax, and in single. Vol. I. G 50 DESCRIPTION OF THE knowledge the likeness of four little knobs to bed-posts ; yet the clynoid processes are very remarkable. The two anter- ior clynoid processes are small bumps, rather sharp, pro- jecting backwards, and terminating in two flat projecting points. The posterior clynoid processes, rise about an inch further backwards, and are, as it were, opposed to the others. They rise in one broad and flat process, which di- vides above into two points, small and round, or knobby at their points; and they look forwards towards the anterior clynoid processes. The sella turcica ephippium, or Turkish saddle, is the space inclosed by these four processes, and is well named. The sella turcica supports the pituitary gland, an appendage of the brain, the use of which is unknown. The carotid arteries rise up by the sides of the sella turcica, and mark its sides with a broad groove. The optic nerves lie upon a groove at the fore part of the sella turcica, betwixt the two anterior clynoid processes ; and sometimes the two anterior processes stretch backwards, till they meet the posterior ones, and form an arch, under which the carotid artery passes. Often the posterior clynoid knobs cannot be fairly distinguished ; since, in many skulls, they form but one broad process. This bone has also its cells, for all that part which we call the body of the bone, all the sella turcica, that space which is betwixt the clynoid processes within and the azygous process without, is hollowed into one large cell, divided with a mid- dle partition. It is indeed less regular than the other cells ; it is sometimes very large, sometimes it is not to be found; it has other trifling varieties, which it were idle to describe. As it communicates with the aethmoid cells, it probably performs one office with them ; is almost a continuation of them, so that when any one is less or wanting, the others are proportionally larger. HOLES.—The sphenoid bone is so placed in the very cen- tre of the skull, that its holes transmit the principal nerves of the skull, and it bears the marks of the chief arteries. 1. The optic holes, are large, round holes, just under each anterior clynoid process. We trace the optic nerves, by a large groove into each optic hole; and an artery goes along with them, named the ophthalmic artery, about the size of a crow-quill, twisting round the optic nerve, and giving arteries to the eyelids, muscles, and lachrymal gland, but most espe- cially to the ball and humours of the eye itself. This ocular or ophthalmic artery comes off from the great carotid, while it lies by the side of the sella turcica ; and it is a branch again of INDIVIDUAL BONES OF THE SKULL. 51 this ocular artery, which goes out upon the forehead, forming the superciliary notch, or hole. 2. The foramen lacerum is next in order, and is so named, because it is a wide slit. The foramen lacerum is wide near the sella turcica, grows gradually narrower as it goes out towards the temple, till it terminates almost in a slit. The upper line of the foramen lacerum is formed by the an- terior clynoid process, extending outwards, sharp and flat: And this is what some have chosen to distinguish by the name of transverse spinous process, or the little wing of Ingra- sias, who had observed it. The nerves of the skull are counted from before backwards. There are nine nerves proper to the skull; the first, or olfac- tory nerve, perforates the cribriform bone ; the 2d, or optic nerve, passes through the optic hole ; the 3d, the 4th, part of the 5th, and the whole of the 6th pairs of the nerves, pass through this foramen lacerum, or wide hole, to go also into the eye. The optic nerve forms the proper organ of vision. The smaller nerves of the 3d, 4th, 5th, and 6th pairs, go to animate its muscles, with the trifling exception of some small twigs, which, passing through the orbit, mount upon the fore- head, or go downwards into the nose. 3. The foramen rotundum, is named from its round shape. The foramen opticum is indeed round, but it has alrea- dy got an appropriated name. Now to give the young anato- mist a regular notion of this, and of the next hole, we must enumerate the branches of the 5th pair. The fifth nerve of the brain is as broad as the little finger, and lies by the side of the sella turcica, where it divides into three lesser nerves, which are called branches of the 5th pair. The first branch of the 5th pair is destined for the eye ; the second branch of the 5th pair for the upper jaw ; the third branch of this 5th pair for the lower jaw : so the first branch of the 5th pair passes through the foramen lacerum to the eye ; the second branch of the 5th pair passes through die foramen rotundum to the upper jaw ; the third branch of this great nerve passes through the foramen ovale to the lower jaw ; and if we had any faith in the doctrines of nervous sympathy, we should say, here is a wide sympathy provided among the nerves of the eye, ths face, and the lower jaw. « The foramen rotundum, then, is a hole exactly round, pretty large, opening immediately under the inner end of the ibramen lacerum, and transmitting the second branch of the 5 th pair of nerves to the upper jaw. -J. The foramen ovale, is an oval hole, larger than the 52 OF THE. BONES foramen rotundum ; about half an inch behind it; and tra mitting the ttiird branch of the 5th pair tfo the lower jaw. 5. The foramen spinale, or spinous hole, is a very small round hole, as if made with a large pin ; is m tne very point of the spinous process ; is one third of an men behind the oval hole, and transmits the small artery less than a crow- quill, which constitutes the chief artery of the dura mater viz. that artery which makes its impression upon the parietal bone. 6. There is still another hole, which transmits a nerve, curious in this respect, that.it is not going out from the skull, but returning into it; for the second branch of the 5th pair, or the superior maxillary nerve, sends a small branch backwards, which having come within the skull, enters the temporal bone, and goes to join itself to the portio dura of the 7th pair, and in its way gives a small branch, to help out the slender begin- ning of the great sympathetic nerve. This retrograde branch of the maxillary nerve gets back again into the skull, by a hole which is found, just under the root of each pterygoid pro- cess, whence it is named pterxgoid hole* ; or by many, is named after its discoverer, the* Vidian holej. This hole is almost hidden under the point of the petrous bone, is not to be seen, but in the separated bones, and is nearly of the size of the spinous hole. If there are found some minute holes about the sella turcica,/ they are only the marks of some blood-vessels, entering the bone to nourish it. CHAP. IV. OF THE BONES OF THE FACE AND JAWS. X HE face is composed of a great number of small bones, ^jhich are grouped together, under the common name of up- pr jaw. There are six bones on either side of the face ; but as their names could convey no distinct notion of the uses, forms, or places of these bones, to enumerate them were but waste of time: they have indeed sutures, and their sutures * This retrograde twig, is the little nerve which perforates the os pet'rosum on its fore part. Vide page 43. ■f- Vidus Vidius, a professor of Paris, and physician to Francis the first OS THE FACE AND JAWS. 53 have been very regularly enumerated ; but these bones meet each other by such thin edges, that no indentation nor proper suture is formed. None of these sutures run for any length, or are of any note ; therefore I have only this to say concern- ing the sutures of the face, that they are acknowledged to be purely a consequence of the ossification having begun in many points : no particular design of nature has been supposed. The sutures, if they require names, are to be named after the bones which they unite. OSSA NASI.-*—The ossa nasi are small bones, rather thin, having no cancelli, being merely firm and condensed plates. They are convex outwardly, so that the two together form nearly an arch. They are opposed to each other by a pretty broad surface, so that their thin arch is firm. They have a flat rough surface, by which they are laid upon the rough sur- face of the frontal bone ; so that there also their connection is strong. They are inclosed by a branch of the upper jaw- bone, which stretching upwards, is named its nasal process : and they lie with their edges under it in one part, and above it in another, in such a way, that they cannot easily be forced in. Lasdy, their lower edge is rough, for the firm attach- ment of the cartilages of the nose ; and their lowest point, or that where the bones of the nose and the gristles of the nose are joined, is the most prominent point (or as it is vulgarly called the bridge) of the nose ; from which connection, not- withstanding its firmness, the cartilages are sometimes luxated. Os unguis, so named from its being of the size and shape of a nail ; or sometimes named the os lachrymale, from its holding the duct which conveys the tears, is that thin scale of bone which I have described as belonging to the os aeth- moides. It is commonly described as a distinct bone ; it is a thin flat bone, asingle scale, without any cancelli; it is found in the inner angle of the eye, at its forepart, and just touch- ing the top of the nose ; it has a large groove in it for holding the lachrymal sac and duct. One half of this bone is behind the groove, and there the eye rolls upon it. One half of it is occupied by the groove for the nasal duct; and the other side of the groove is formed by the rising branch, or nasal procete, as it is called, of the upper jaw-bone. The os unguis is 'deli- cate, and easily broken, being as thin as a sheet of paper. It is this bone which is pierced in the operation for the fistula lachrymalis ; which is easily done, almost with a blunt steel or probe ; and the chief caution is to keep forwards, so as to per- forate in the place of the groove, as that will lead into the nose, and not behind it, which would cany the perforating in- 54 OF THE BONES strument into the ethmoidal sinuses, and perhaps wound the spongy bone. . . , This bone seems peculiarly liable to caries, which is perhaps the nature of all these thin bones ; for as they have no mar- row, they must depend entirely on their periosteum, which they are no sooner robbed of than they die. Ossa maxillaria superiora.—The upper jaw-bones are particularly worthy of notice ; for here we find all that is curi- ous in the face, even to its size and shape. The upper jaw- bones are of very great size, forming as it were the founda- tion or basis of the face. They send a large branch upwards, which forms the sides of the nose ; a broad plate goes back- wards, which forms the roof of the palate ; there is a circular projection below, which forms the alveoli, or sockets of the teeth. The upper jaw-bones are quite hollow within, forming a very large cavity, which is capable of containing an ounce of fluid or more. The size of this cavity seems to determine the height of the cheek-bone, and the form of the face ; and the diseased enlargement of this cavity raises the cheek-bone, lessens the eye, and deforms the face in a very extraordinary degree. These processes, and this cavity of the bone, are what de- ' serve most particular notice. 1. The first is the nasal process, which extends upwards, to form the side of the nose. It is arched outwards, to give the nostrils shape. Its sides support the nasal bones ; and the cartilages of the alae nasi, or wings of the nose, are fixed to the edges of this process. 2. A plate of this bone is called the orbitary process. This thin plate is the roof of the great cavity, which occupies this bone entirely. It is at once as a roof to the antrum maxillare and as a floor for the eye to roll upon. There is a wide groove along the upper surface of this plate, in which the chief branch of the upper maxillary nerve lies : and this branch, named infra orbitary nerve from its lying thus under the eye, comes out by a hole of the jaw-bone under the eye, which is named infra orbitary hole. And thus the nerve appearing upon the cheek, is the chief nerve of the face. 3. This great bone is the basis upon which the cheek-bone stands ; and that it may have a firm place, there is a rough and (as anatomists call it) scabrous surface, which makes a very firm suture with the cheek-bone ; and as this surface rises a little, it is named the malar process. 4. From the lower circle of this bone, there projects a semi- circle of bone, which is for lodging the teeth of the upper jaw. This circle of bone is as deep as the fangs of the teeth are OF THE FACE AND JAWS. .55 long. And it may be very truly named a process (processus alveolaris,) since it does not exist in the foetus, nor till the teeth begin to be formed ; since it grows along with the teeth and is absorbed and carried clean away when in old age the teeth fall out. The sides of the sockets in which the teeth are lodged are extremely thin, and surround them closely. The teeth are so closely embraced by their sockets, and we are so far from being possessed of any instrument by which they can be pulled perpendicularly out, that the sockets can seldom escape ; they are broken or splintered in perhaps one of four extractions, even by the most dexterous artists in that line. 5. The palate process is a plate of bone which divides the nose from the mouth, constituting the roof of the palate, and the floor or bottom of the nostrils. This plate is thinner in its middle, and thicker at either edge : thus, it is thick where it first comes off from the alveolar process ; it is thin in its middle ; and it is again thick where it meets its fellow of the opposite side. For at the place where the two upper jaw- bones meet, the palate plate is turned upwards, so that the two bones are opposed to each other in the middle of the palate, by a broad flat surface, which cannot be seen but by separating the bones. This surface is so very rough, that the middle palate suture almost resembles the sutures of the skull; and the maxillary bones are neither easily separated, nor easily joined again. This meeting of the palate plates by a broad surface, makes a rising spine, or sharp ridge towards the nos- trils ; so that the broadness of the surface by which these bones meet, serves a double purpose; it joins the bones se- curely, and it forms a small ridge upon which the split edge of the vomer, or partition of the nose, is planted. Thus we find the palate plate of the maxillary bones conjoined ; forming almost the whole of the palate, while what are properly called the palate bones form a very small share of the back part only. As these thinner bones of the face have no marrow, they are nour- ished by their periosteum only ; they are of course perforated with many small holes. A great many minute holes are found along the palate plate, about the place of the sockets, and in- deed all over the maxillary bones: and this is particular in the palate, that the hard membrane or covering of it, is fixed to the bony plate by many rough tubercles, and even by small hooks, which are easily seen in the dried bone. 6. The antrum maxillare, or cavity of the jaw-bone, is commonly named antrum highmorianum, after its dis- coverer Highmore. We have gone round the antrum, on all its sides, in describing these processes of the bone : the palate plate makes the floor of the antrum ; the orbitary process 56 OF THE BONES makes its roof; the cheek, quite up from the sockets ot the teeth to the lower part of the eye, forms its walls, or sides ; so that when the antrum enlarges, it is the cheek that becomes deformed ; and when we design to open the antrum, we either perforate the cheek, or pull one of the teeth. The antrum is concave towards the cheek, but it has a flat side towards the nose ; it is divided from the cavity of the nostril by a flat and very thin plate of bone ; it seems in the naked skull to have a very wide opening, and the lower spongy bone is hung by a small hook upon the edge of this thin septum, which divides the antrum from the nose ; but in the skull, covered with its soft parts, we find the antrum almost closed by a membrane which stretches over the opening, and leaves but one or two very small holes of the size of the smallest pea, by which, perhaps, the reverberation of sound in the antrum is more effectual in raising the voice, and by which small hole, the mucus, which is secreted in the antrum, drops out into the nose. The cavity of the antrum, like the inner surfaces of the nostrils, is covered with a membrane, and is bedewed with mucus ; and the mucus drops more or less freely in various positions of the head. Sometimes by cold or other accidents, inflammations and swellings of the membrane come on ; the holes are closed ; the drain of matter is suppressed and con- fined within, and the cheek swells. Perhaps there may be some particular disease of the membrane with which the cavi- ty is lined, or of the bone itself; in one way or other, diseases of this cavity, and collections of matter, dreadful pain and caries of the bone are very frequent; then the cheek rises; the face is irrecoverably deformed ; sometimes the matter makes its way by the sides of the teeth, or at last, it bursts through the bones, makes an ulcer in the cheek ; and then there is a natural cure, but slow and uncertain. There is no veiy sure mark of this disease ; it may be known by an attentive retrospect of all the circumstances. The disease is not to be easily nor certainly discovered; but a very long continued toothach, an uncommon degree of pain, or greater affection of the eye, with a swelling and redness, and gradual rising of the cheek, are very suspicious signs. The pulling of the second or third of the grinding teeth, often brings a splinter away with it, which opens a road for the matter to flow; or though there be no breach of the socket, often the confined matter follows the teeth, because not unfrequently the longer fangs of the grinders naturally penetrate quite into this cavity of the jaw : if the matter should not flow, the floor of the antrum is easily perforated, by introducing a sharp stillet by the socket of the tooth that is pulled. The flow of the matter OF THE FACE AND JAWS. 57 gives relief, and injections of various medicines complete the cure. But as this opening is sometimes a cure, it is some- times also a disease ; for the breaking of a socket, sometimes opening a way into this antrum, there follows inflammation of its internal surface, a running of matter, and sometimes caries of the bone. Holes.—The holes of the jaw-bone are two only: 1. The infra-orbitary hole, for transmitting the infra-orbitary nerve from the bottom of the eye, comes along under the eye in a bony groove, and makes generally one large round hole on the cheek, just under the margin of the orbit, or sometimes the nerve divides and makes two smaller holes in its passage upon the cheek ; and, 2. A hole in the palate plate, which be- longs equally to each of the palate bones ; for it is betwixt the two bones in the forepart, or beginning of the palate suture be- hind the two first cutting teeth. This hole is named foramen incisivum, as opening just behind the incisive or cutting teeth ; or it is named anterior palatine hole, to distin- guish it from one in the back of the palate: this hole is large enough to receive the point of a quill; it is single towards the mouth; but towards the nose, it has two large openings, one opening distinctly into each nostril. 3. But it will be well to explain here a third hole, which is common to the maxillary with the proper palate bones. It is formed on the back part of the palate (one on either side), in the suture which joins the palate bones to the jaw-bones: it is named posterior palatine hole: it is as large as the in- terior palatine hole, but it serves a much more important pur- pose ; for the upper maxillary nerve sends a large branch to the palate, which branch comes down behind the back of the nos- tril, perforates the back of the palate, by the posterior palatine hole, and then goes forward in two great branches along the palate. Thus the chief, or, we might say, the only nerves of the palate come down to it through these posterior palatine holes; but the use of the anterior palatine hole is a problem still; for we cannot believe that so great a hole, so very regu- lar, and so curiously divided, so as to open into the two nos- trils, can be quite useless; yet the meaning of this hole has ne- ver been explained. It looks almost as if it were merely de- signed for giving the soft palate a surer hold upon the bone; for no ducts have been found opening into the palate from the nose; nor any glands with their ducts seated here; nor any nerves passing either from the nose to the palate, or from the palate to the nose; nor any artery, except one of the most tri- fling size. In 3hort, anatomists having sought with care for Vol. I. H 58 OF THE BONES any thing that might explain its use, have still found nothing but the hard membrane filling up the anterior hole. The whole surface of the bone which forms the antrum is perforated with frequent small holes, especially to^aras "s back part, transmitting small arteries and nerves to the teem and the back of the antrum forms with the orbitary part of the sphenoid bone a second foramen lacerum for the eye ; an irre- gular opening towards the bottom of the socket, which is tor the accumulation of fat, not for the transmission ol nerves; and it is from the wasting of this fat, taken back into the sys- tem, that the eye sinks so remarkably in fevers, consumptions, and such other diseases as waste the body. The OSSA PALATI, or PALATE BONES—are very small, but have such a number of parts, and such curious con- nections as are not easily explained. They seem to eke out the superior maxillary bones, so as to lengthen the palate, and com- plete the nostrils behind: they even extend upwards into the socket, so as to form a part of its circle ; although, in looking for them upon the entire skull, all these parts are so hidden, that we should suppose the palate bones to be of no greater use nor extent than to lengthen the palate a little backwards. The parts of the palate bone are these : 1. The palatal plate, or process of the palate bone, whence it has its name, lies horizontal in the same level with the palatal process of the jaw-bone, which it resembles in its rough and spinous surface ; in its thinness ; in its being thin- ner in the middle, and thicker at either end; in its being oppo- sed to its fellow by a broad surface, which completes the mid- dle palate suture ; and it is connected with the palate pro- cess of the jaw, by a suture resembling that by which the op- posite bones are joined ; but this suture going across the back part of the palate, is named the transverse palate suture. Where the two palate bones are joined, they run backwards in- to an acute point; on either side of that middle point, they make a semicircular line, and again run out into two points be- hind the grinding teeth of each side. By this figure of the bones, the back line of the palate has a scolloped or waved form. The velum palati, or curtain of the palate, is a little arched, following the general line of the bones; the uvula or pap hangs exactly from the middle of the velum, taking its origin from the middle projecting point of the two bones ; and a small muscle, the azygus uvulae, runs down in the middle of the velum, taking its origin from this middle point. 2. The small projecting point of the palate bone, just be- hind the last grinding tooth, touches the pterygoid process of OF THE FACE AND JAWS. 59 the sphenoid bone; it is therefore named the pterygoid pro- cess of the palate bone ; but it is so joined with the pterygoid process of the sphenoidal bone, that they are not to be distin- guished in the entire skull. The posterior pterygoid hole, or third hole of the palate, is just before this point. 3. The nasal plate or process, is a thin and single plate ; rises perpendicularly upwards from the palate ; lies upon the side and back part of the nostrils, so as to form their opening backwards into the throat; it is so joined to the upper jaw- bone, that it lies there like a sounding-board upon the side of the antrum Highmorianum, and completes that cavity forming the thin partition betwixt it and the nose. 4. This nasal process extends thus up from the back arch of the palate to the back part of the orbit; and though the nasal plate is very tilin and delicate in its whole length, yet, where it enters into the orbit, it is enlarged into an irregular kind of knob of a triangular form. This knob is named its orbitary process ; or, as the knob has two faces looking two ways in the orbit, it is divided sometimes (as by Monro the father) into two orbitary processes, the anterior and posterior ; the anteri- or one is the chief. This orbitary process, or point of the pa- late bone, being triangular, very small, and very deep in the socket, is not easily discovered in the entire skull. 5. This orbitary process is most commonly hollow or cellu- lar, and its cells are so joined to those of the sphenoid bone, that it is the palate bone that shuts the sphenoid cells, and the sphenoid and palatine cells of each side constitute but one general cavity. The OSSA SPONGIOSA, or TURBINATA, INFE- RIORA, are so named, to distinguish them from the upper spongy bones, which belong to the os aethmoides ; but these lower spongy bones are quite distinct, formed apart, and con- nected in a very slight way with the upper jaw-bones. The ossa spongiosa inferiora, are two bones, much rolled or convoluted; very spongy ; of a light and scaly ap- pearance, with holes and an appearance of net-work resem- bling the sponginess of puffed paste, so that they are exceed- ingly light. They lie rolled up in the lower part of the nose ; are particularly large in sheep ; are easily seen either in the en- tire subj ect, or in the naked skull. Their point forms that pro- jection, which is touched with the finger in picking the nose ; and from that indecent practice, very often serious consequen- ces arise, for iu many instances, polypi of the lower spongy 60 OF THE BONES bones, which can be fairly traced to hurts of this kind, grow so, as to extend down the throat, causing suffocation and-death. One membrane constitutes the universal ^*™™ ties of the nose, and the coverings of all the ^ongy bones This continuity of the membrane, prevents our seeing in the subject, how slightly the spongy bones are hu"8L*^nnn the bare and dissected skull, we find a neat small hook upon the spongy bone, by which it is hung upon the edge of the antrum maxillare; for this lower spongy bone is laid upon the side ot the antrum so as to help the palate bone, in closing or covering that cavity from within. One end of the spongy bone, rather more acute, is turned towards the opening of the nostril, and covers the end of the lachrymal duct: the other end of the same bone, points backwards towards the throat. The curl- ♦ ing plate, hangs down into the cavity of the nostril, with its arched side towards the nose. This spongy bone differs from the spongy process of the aethmoid bone, in being less turbinat- ed or complex; in having no cells connected with it; and per- haps it is less directly related to the organ of smell. If polypi arise from the upper spongy bone, we can use less freedom, and dare hardly pull them away, for fear of injuring the cribri- form plate of the aethmoid bone : we are indeed not absolutely prohibited from pulling the polypi from the upper spongy bone: but we are more at ease, in pulling them from the lower one, since it is quite an insulated bone. When peas, or any such foreign bodies, are detained in the nose, it must be from their swelling, and being detained among the spongy bones. The spongy bones are not absolutely limited in their num- ber : there is sometimes found betwixt these two, a third set of small turbinated bones, commonly belonging to the aethmoid bone. VOMER.—The nose is completed by the vomer, which is named from its resemblance to a ploughshare, and which di- vides the two nostrils from each other. It is a thin and slen- der bone, consisting evidendy of two plates much compressed together; very dense and strong, but still so thin as to be trans- parent. The two plates of which the vomer is composed, split or part from each other at every edge of it, so as to form a groove on every side. 1. On its upper part, or as we may call it, its base, by which it stands upon its skull, the vomer has a wide groove, receiving the projecting point of the aethmoid and sphenoid bones : thus it stands very firm and secure, and capable of resisting very violent blows. 2. Upon its lower part, its groove is narrower, and receives the rising line in the middle of the palate plate, where the bones meet, to form the Or THE FACE AND JAWS. 61 palate suture. At its forepart, it is united by a ragged sur- face, and by something like a groove, to the middle cartilage of the nose ; and as the vomer receives the other bones into its grooves, it is, in a manner, locked in on all sides : it receives support and strength from each ; and if the vomer and its car- tilage should seem too slender a support for the fabric of the nose, let it be remembered, that they are all firmly connected, and covered by one continuous membrane, which is thick and strong, and that this is as a periosteum, or rather like a conti- nued ligament, which increases greatly the thickness and the strength of every one of these thin plates. The vomer, in al- most every subject, bends much towards one or other nostril, so as sometimes to occasion no small apprehension, when it happens to be first observed. OS MALiE, or the bone of the cheek, is easily known, and is a very unimportant one. It is that large square bone which forms the cheek: it has four distinct points, which anatomists have chosen to demonstrate, with a very superflu- ous accuracy. 1. The upper orbitary process stands high- est, running upwards to form part of the socket, the outer corner of the eye, and the sharp edge of the temple. 2. The inferior orbitary process, which is just opposite to this, forming the lower part of the orbit, and the edge of the cheek.' 3. The maxillary process, is that broad and rough surface, by which it is joined to the upper jaw-bone. 4. There is another process, the best entided to the name of process, be- cause it stands out quite insulated, and goes outwards and backwards to unite with the temporal bone, in forming the zygoma or temporal arch ; it is named the zygomatic pro- cess. 5. That plate, which goes backwards to form the floor of the orbit, is named the internal orbitary process. This bone has no holes, except such minute ones as transmit arter- ies, merely for the nourishment of the bone itself. 9S MAXILLAE TNFERIORIS—The lower jaw-bone, is likened to a horse-shoe, or to a crescent, or to the letter U, though we need be under no anxiety about resemblances for a form so generally known. There is such an infinite complica- tion of parts surrounding the jaw, of glands, muscles, blood- vessels, and nerves, that it were endless to give even the slight- est account of these. They shall be reserved each for its pro- per place, while I explain the form of the lower jaw, in the most simple and easy way. 1. The forepart, or chin, is, in a handsome and manly face, veiy square ; and this portion is marked out by this square- 62 OP THE BONES ness, ,, and by two small holes, one on either side, by which the. nerves of the lower jaw pome out upon the face. 2. The base of the jaw, is a straight and even line, ter- minating the outline of the face. It is distinctly traced all along, from the first point of the chin, backwards to the angle of the jaw. Fractures of this bone are always more or less transverse, and are easily known by the falling down of one part of this even line, and by feeling the crashing bones when the fallen part is raised. Such fractures happen from blows or falls ; but not by pulling teeth, for the sockets of the teeth bear but a small proportion to the rest of the jaw ; even in children this cannot happen, for in them the teeth have no roots, and have no hold nor dangerous power over the jaw. Though (as I have said) the sockets often suffer, the jaw itself never yields. 3. The angle of the jaw, is that comer where the base of the jaw ends, where the bone rises upwards, at right angles, to be articulated with the head. This part also is easily felt, and by it we judge well of the situation of veins, arteries, and glands, which might be in danger of being cut, in wounds or in operations. There are two processes of the jaw, of parti- cular importance, the coronoid or horn-like process, for the in- sertion of its strong muscles, especially of the temporal mus- cle, and the condyloid or hinge process, by which it is jointed with the temporal bone. 4. The' coronoid process, named from its resemblance to a horn, is, like the rest of the jaw-bone, flat on its sides, and turned up with an acute angle, very sharp at its point, and lying exactly under the zygoma, or temporal arch. The temporal muscle runs under this arch, and lays hold on the coronoid pro- cess ; not touching it on one point only, but grasping it on every side, and all round. And the process is set so far before the articulation of the jaw, that it gives the muscle great power. This process is so defended by the temporal arch, and so co- vered by muscles, that it cannot be felt without. 5. The condyloid process, or the articulating process of the jaw, is behind this, and is formed by the body of the bone turned up at its angle. This also is of the same flat form with the rest of the jaw. The condyle, or joint of the jaw-bone, is placed upon the top of this rising branch. The condyle, or articulating head, is not round, but flat, of a long form, and set across the branch of the jaw. This articulating process is re- ceived into a long hollow of the temporal bone, just under the root of the zygomatic process ; so that by the long form of the condyles, and of the cavity into which it is received, this joint is a mere hinge, not admitting of lateral nor rotatory motions OF THE FACE AND JAWS. 63 at least of no wider lateral motions than those which are ne- cessary in grinding the food ; but die hinge of the jaw is a complex and very curious one, which shall be explained in its proper place. 6. The alveolar process, or the long range of sockets for the teeth, resembles that of the upper jaw. The jaw, as the body grows, is slowly increasing in length, and the teeth are added in proportion to the growth of the jaws. When the jaws have acquired their full size, the sockets are completely filled; the lips are extended, and the mouth is truly formed. In the decline of life, the teeth fall out, and the sockets are re- absorbed, and carried clean away, as if they had never been ; so that the chin projects, the cheeks become hollow, and the lips fall in, the surest marks of old age. The successive changes of the form of the jaw are worthy of being mentioned once more ; first, That in the child, the jaw consists of two bones, which are joined slightly together in the chin. This joining, or symphysis, as it is called, is easily hurt, so that in preternatural labours it is, according to the common method of pulling by the chin, always in danger, and often broken. During childhood the processes are blunt, and short, do not turn upwards with a bold and acute angle, but go off obliquely from the body of the bone. The teeth are not rooted, but sticking superficially in the alveolar process ; and another set lies under them, ready to push them from the jaws. Secondly, That in youth, the alveolar process is extending. the teeth are increasing in number. The coronoid and articu- lating processes are growing acute and large, and are set off at right angles from the bone. The teeth are now firmly rooted; for the second set has come up from the substance of the jaw. Thirdly, In manhood, the alveolar process is still more elongated. The dentes sapientise are added to the number of the teeth ; but often, by this, the jaw is too full, and this last tooth coming up from the backmost part of the alveolar process in either jaw, it sometimes happens, that the jaw cannot easily close ; the new tooth gives pain; it either corrupts, or it needs to be drawn. Fourthly, In old age, the jaw once more falls flat; it shrinks according to the judgment by the eye, to half its size ; the sockets are absorbed, and conveyed away; and in old age the coronoid process rises at a more acute angle from the skull, and by the falling down of the alveolar process, the coronoid process seems increased in length. 64 OF THE TRUNK. HOLES.—-The holes of the lower jaw-bone are chiefly two. 1. A large hole on the inner side, and above the angle of the jaw, just at the point where these two branches, the con- dyloid and the coronoid processes part. A wide groove from above downwards, leads to the hole ; and the hole is, as it were, defended by a small point, or pike of bone, rising up from its margin. This is the great hole for admitting the lower maxillary nerve into the hollow of the jaw, where it goes round within the circle of the jaw, distributing its nerves to all the teeth. But at the point where this chief branch of the nerve goes down into the jaw, another branch of the nerve goes forward to the tongue. And as nerves make an impression as deep as that of arteries in a bone, we find here two grooves, first, One marking the place of the great nerve, as it advances towards its hole; and, secondly, A smaller groove, marking the course of the lesser branch, as it leaves the trunk, and passes this hole to go forward to the tongue. Along with this nerve, the lower maxillary artery, a large branch, enters also by the hole ; and both the nerve and artery, after having gone round the canal of the jaw, emerge again, upon the chin. 2. The second hole of the lower jaw is that on the side of the chin, about an inch from the point which permits the remains of the great nerve and artery (almost expended upon the teeth) to come out upon the chin; it is named the mental hole. CHAP. V. OF THE TRUNK, OR, THE SPINE, THORAX, AND PELVIS. THE SPINE. X HE spine is so named from certain projecting points of each bone, which standing outwards in the back, form a con- tinued ridge j and the appearance of continuity is so com- OF THE TRUNK. 65 plete, that the whole ridge is named spine, which, in common language, is spoken of as a single bone. This long line con- sists of twenty-four distinct bones, named vertebrae, from the Latin vertere, to turn. They conduct the spinal marrow, secure from harm the whole length of the spine ; and support the whole weight of the trunk, head and arms ; they perform at certain points, the chief turnings and bendings of the body; and do not suffer under the longest fatigue, or the greatest weight which the limbs can bear. Hardly can any thing be more beautiful or surprising than this mechanism of the spine, where nature has established the most opposite and inconsist- ent functions in one set of bones ; for these bones are so free in motion, as to turn continually, yet so strong as to support the whole weight of the body; and so flexible as to turn quickly in all directions, yet so steady within, as to contain and defend the most material and the most delicate part of the nervous system. The vertebras are arranged according to the neck, back, and loins, and the number of pieces corresponds with the length of these divisions. The vertebrae of the loins are five in num- ber, very large and strong, and bearing the whole weight of the body. Their processes stand out very wide and free, not entangled with each other ; and perform the chief motions of the trunk. The vertebrae of the back are twelve in number. They also are big and strong, yet smaller than those of the loins ; their processes are laid over each other; each bone is locked in with the next, and embarrassed by its connection with the ribs ; this is therefore the steadiest part of the spine, a very limited motion only is allowed. The vertebrae of the neck are seven in number; they are more simple, and like rings ; their processes hardly project; they are very loose and free ; and their motions are the widest and easiest of all the spine. • The seven vertebras of the neck, twelve of the back, and five of the loins, make twenty-four in all, which is the regu- lar proportion of the spine. But the number sometimes va- ries according to die proportions of the body ; for where the loins are long, there are six vertebrae of the loins, and but eleven in the back ; or the number of the pieces in the back is sometimes increased to diirteen ; or the neck, according as it is long or short, sometimes has eight pieces, or sometimes only six. General description of a vertebra.—The general form, processes, and parts of the vertebra, are best exempli- fied in a vertebra of the loins ; for in it the bodv is large, the Vol. I. I 66 OF THE TRUNK. processes are right lined, large, and strong; the joint is com- plete, and all its parts, are verv strongly marked. Every vertebra consists of a body, which is firm for supporting the weight of the body, and hollow behind, for transmitting the spinal marrow; of two articulating processes above, and two below, by which it is jointed with the bones which are above and below it; of two transverse processes, which stand out from either side of the bone, to give hold and purchase. to those muscles which turn the spine ; and of one process, the spinous process, which stands directly backwards from the middle of the bone ; and these processes being felt in distinct points all the way down the back, give the whole the appear- ance of a ridge ; whence it has the name of spine. 1. The body of the vertebra is a large mass of soft and spongy bone ; it is circular before, and flat upon the sides. It is hollowed into the form of a crescent behind, to give the shape of that tube in which the spinal marrow is contained. The body has but a very thin scaly covering for its thick and spongy substance. It is tipped with a harder and prominent ring above and below, as a sort of defence, and within the ring the body of the vertebra is hollowed out into a sort of su- perficial cup, which receives the ligamentous substance by which the two next vertebrae are joined to it; so that each ver- tebra goes upon a pivot, resembles the ball and socket-joints; and in many animals it is distinctly a joint of this kind. 1. The body is the main part of the vertebra to which all the other processes are to be referred ; it is the centre of the spine, and bears chiefly the weight of the body : it is large in the loins, where the weight of the whole rests upon it, and where the movements are rather free : it is smaller in the ver- tebrae of the back, where there is almost no motion, and less weight; and in the vertebrae of the neck, there is hardly any body ; the vertebrae being joined to each other chiefly by the articulating processes. 2. The articulating process is a small projection, standing out obliquely from the body of the vertebra, with a smooth surface, by which it is joined to the articulating pro- cess of the next bone ; for each vertebra has a double articula- tion ; with that above and with that below. The bodies of the vertebrae are united to each other by a kind of ligament, which forms a more fixed, and rather an elastic joining; and they are united again by the articulating processes ; which makes a very moveable joint of the common form. The arti- culating processes are sometimes named oblique processes, because they stand rather obliquely. The upper ones -ire na- med the ascending oblique processes, and the two lower ones are named the inferior or descending oblique processes. OF THE TRUNK. 67 3. The spinous processes are those which project directly backwards, whose points form the ridge of the back, and whose sharpness gives the name to the whole column. The body of each vertebra sends out two arms, which, meeting behind, form an arch or canal for the spinal marrow ; and from the middle of that arch, and opposite to the body, the spinous process projects. Now these spinous, and the trans- verse processes, are so many handles and levers by which the spine is to be moved ; which, by their bigness, give a firm hold to the muscles; and, by their length, give them a pow- erful lever to work their effects by. The spinous processes, then, are for the insertion of these muscles which extend and raise the spine. 4. The transverse processes stand out from the sides of the arms or branches which form this arch. They stand out at right angles, or transversely from the body of the bone ; and they also are as levers, and long and powerful ones for moving and turning the spine. Perhaps their chief use is not for turning the vertebrae ; for there is no provision for much of a lateral motion in the lower part of the spine, but the muscles which are implanted into these are more commonly used in as- sisting those which extend and raise the spine. These, and all the processes, are more distinct, prominent, and strong, more direct, and larger in the loins, and more easily understood, than in the vertebrae of any other class. But this prepares only for the description of the individual vertebrae, where we find a variety proportioned to the various offices, and to the degrees of motion which each class has to perform. Of the vertebra of the loins.—I have chosen to re- present the general form of a vertebra, by describing one from the loins, because of the distinctness with which all its parts are marked. In the lumbar vertebrae, the perpendicular height of the body is short; the intervertebral substance is thicker than in the other parts of the spine ; and the several processes stand off from each other distinct and clear; all which are pro- visions for a freer motion in the loins. The body of a lumbar vertebra is particularly large, thick, and spongy; and its thin outer plate is perforated by many arteries going inwards to nourish this spongy substance of the bone. The length of the body is an inch, and the intersticial cartilage is nearly as long: so that the vertebrae of the loins present to the eye, looking from within the body, a large thick and massy column, fit for supporting so great a weight. 68 OF THE TRUNK. The spinous process is short, big, and strong. It rum secure hold which they have. The transverse process is also short, BONES OF THE of the metacarpal bones in general, 1. That their lower heads being flat and squared, gives them a firm implantation upon their centre or nucleus, the carpus ; and that they have scarce- ly any freer motion upon the carpal bones, than the carpal bones have upon each other. 2. That their lower heads being larger, keeps the bones apart from each other ; and in the in- terstices between them lie the interosseous muscles. 3. That their divergence regulates the radiated or spreading form of the fingers, and gives them free play. And, 4. That they still preserve the arched form of the carpal bones, being, with the carpal bones, convex outwardly, and concave inwardly, to form the hollow of the hand ; and though they have little motion of flexion or extension, they bend towards a centre, so as to ap- proach each other, increasing the hollowness of the hand, to form what is called Diogenes's cup. It is farther necessary to observe, into how small a space the carpal bones are compres- sed ; how great a share of the hand the metacarpal bones form ; and how far down they go into the hollow of the hand. For I have seen a surgeon, who, not having the smallest sus- picion that their lower ends were so near the wrist as they really are, has, in place of cutting the bone neatly in its arti- culation with the carpus, broken it, or tried to cut it across in the middle. FINGERS.—We commonly say, that there are five me- tacarpal bones ; in which reckoning we count the thumb with the rest: but what is called the metacarpal of the thumb is properly the first phalanx, or the first proper bone of the thumb ; so that the thumb, regularly described, has, like the other fingers, three joints. Thumb.—The first bone of the thumb resembles the meta- carpal bones in size and strength, but it differs widely in being set upon the carpus with a large and round head ; in being set off from the line of the other fingers, standing out on one side, and directly opposed to them. It rolls widely and freely, like other ball and socket joints ; it is opposed to the other fingers in grasping, and, from its very superior strength, the diumb is named Polex, from polere. The fingers have each of them three bones. 1. The first bone is articulated with the metacarpal bones by a ball and socket; the socket, or hollow on the lower part of the first fin- ger bone, being set down upon the large round head of the me- tacarpal bone. 2. The second and third joints of the fingers are gradually smaller, and though their forms do a good deal resemble the first joint, they are quite limited in their mo- tions ; have no rolling ; are as stricdy hinge-joints as the knee SHOULDER, ARM, AND HAND. 117 or ankle are. 3. Here, as in other hinge-joints, the capsule is so particularly strong at the sides, as to be named lateral li- gaments. When these lateral ligaments are burst or cut, the finger turns in any direction, so that the motions of the fingers are limited rather by their lateral ligaments, than by any thing peculiar in the forms of the bones. 4. The face of each finger bone is grooved, so that the tendons, passing in the palm of the hand, run upwards along this groove or flatness of the fin- gers ; and from either edge of this flatness, there rises a liga- ment of a bridge-like form, which covers the tendons like a sheath, and converts the groove into a complete canal. 5. The last joint or phalanx of each finger is flattened, rough, and drawn smaller gradually towards the point of the finger ; and it is to this roughness that the skin and. nail adhere at the point. BOOK II. OF THE MUSCLES. — "• CHAP. I. MUSCLES OF THE FACE, EYE, AND EAR. muscles of the face. I. 1 HE OCCIPITO FRONTALIS is a broad and thin muscular expansion, which covers all the upper part of the cra- nium. It consists of two bellies, with an intermediate sheet of flat tendon. The one belly covers the occiput; the other covers the forehead ; and the tendinous expansion covers all the upper part of the head : by which it has happened that the most eminent anatomists, as Couper (p. 29.) have misnamed its tendon, pericranium : many have reckoned it two distinct muscles, viz. the occipital and frontal ; while others (because of a sort of rapha, or line of division in the middle of each belly) have described four muscles, viz. two frontal and two occipital muscles. But it is truly a double bellied muscle ; and the broad thin tendon, which belongs equally to both bellies, lies above the true pericranium, and slides upon it. The muscle is therefore named, with strict propriety, oc- cipito-frontalis, sometimes epicraneus, sometimes bi- VENTER Or DIGASTR1CUS CAPITIS. Origin—The occipital portion is the fixed point of this muscle ; arising from the upper ridge of the occipital bone, and covering the back part of the head, from the mastoid pro- cess of one side, round to that on the opposite side of the head. And by the perpendicular ridge of the occiput, it is marked with a slight division in the middle. Insertion.—The fore belly of the muscle which covers the forehead, is fixed more into the skin and eyebrows than into the bone ; it is slightly attached to the bone, near the inner end of the orbitary ridge, and especially about the inner cor- ner of the eye, and the root of the nose, by a smaller and acute face, eye, and ear. 119 pointed process ; but still its chief attachment is to the eye-lids and skin. The tendon or thin membraneous expansion which joins the two bellies, is exceedingly thin : it has on its inner side much loose cellular substance, by which, though attached to the true pericranium, it slides easily and smoothly upon it; but its outer surface is so firmly attached to the skin, and its fore bel- ly adheres so firmly to the eyebrows, that it is very difficult to dissect it clean and fair. I consider the occipital belly as the fixed point, having a firm origin from the ridge of the bone ; its frontal belly has the loose end attached, not to the os frontis, but to the eye- brow and skin ; and its office is to raise the eyebrows, wrinkle the forehead, and corrugate the whole of the hairy scalp, like that muscle under the skins of animals which shrinks when they are cold or rudely touched, and by which they shake off flies or insects. But it is a muscle employee} more in expres- sing passions than in performing useful motions ; and it is often so thin as hardly to be perceived. In some it is entirely wanting; and many who have the muscle, have no command nor power over it. There is a small, neat, and pointed slip of the occipito-front- alis, which goes down with a peak towards the nose, and is in- serted into the small nasal bone. This process, being much below the end of the eyebrow, must pull it downwards ; so that while the great muscle raises the eyebrow and skin of the forehead, this small nasal slip pulls the eyebrow downwards again, restoring it to its place, and smoothing the skin. It may be considered as the antagonist of the great occipital and frontal bellies, and might almost be described as a distinct muscle. II. The corrugator supercilii is another slip which might be fairly enough referred, like this, to the occipital muscle ; but being in many subjects particularly strong, it is best described as distinct. The lower end of the nasal slip of the occipito-frontalis is fixed to the nasal bone ; the lower end of the little slip, the corrugator supercilii, is fixed into the in- ternal angular process ; and from the inner angle of the eye, , the fibres sweep round the edge of the orbit, and going ob- liquely upwards and outwards, are so mixed with the fibres of the frontal muscle, and of the orbicularis oculi, where these two touch each other, that it is doubtful to which of those greater muscles this little one might be most properly referred. So this slip of oblique fibres, rising from the inner angle of the eye, and being fixed into the eyebrow, also antagonizes the occipito-frontalis ; and drawing the eyebrows together, and 120 muscles of the wrinkling the space betwixt them, is very rightly named cor- rugator supercilii. . . , III. Orbicularis oculi, or palpebrarum, is a neat and regular muscle, surrounding the eye, and covering the eyelids in a circular form. It is exceedingly flat and thin; is about an inch in breadth ; lies immediately under the skin ot the eyelids ; and is immediately attached to them, and but little connected with the bone. It has one small tendon in the inner corner of the eye, which is both its origin and insertion ; for it begins and ends in it. This small tendon is easily felt through the skin in the inner corner of the eye. It arises by a little white knot from the nasal process of the upper jaw-bone. Its fibres immediately become muscular, and spread out thin over the upper eyelid. They pass'over it to the outer corner of the eye, where they cross a little, and having covered just the edge of the temple with their thin expanded fibres, they return in a circular form round by the lower eyelid to the point from whence they had set out. This is, in all its course, a very thin muscular expansion, with regular orbicular fibres. It is rather a litde broader over the lower eyelid ; extends itself a little upon the face beyond the brim of the socket, both at the tem- ple and upon the cheek ; and its fibres cross each other a little at the outer nngle ; so that some, understanding this crossing as a meeting of fibres from the upper and from the lower mus- cle, have described it as two semicircular muscles. And those fibres which are next to the tarsus or cartilaginous circle of the eyelids, were distinguished by Riolan under the title of mus- culus ciliaris. Our name expresses the common opinion, that it is a circular muscle, whose chief point or fulcrum is in the inner corner of the eye, and which serves as a sphincter for closing the eye. It squeezes with spasmodic violence when the eye is injured, as by dust. And by its drawing down the eyelids so firmly, it presses the ball of the eye down into the socket, and forces the lachrymal gland that is within the sock- et, so as to procure a flow of tears. Perhaps the corrugator supercilii belongs strictly to this muscle, since its fibres follow the same course. IV. Levator palpebrjE superioris.—This small mus- cle arises deep within the socket, from the margin of that hole which gives passage to the optic nerve. It begins by a small flat tendon in the bottom of the optic cavity ; becomes gradu- ally broader as it goes over the eyeball; it ends in the eyelid by a broad expansion of muscular fibres, which finally terminate in a short flat tendon. It lies under the orbicularis palpebras; is inserted into the whole length of the cartilage of the tarsus ; and raises and opens the upper eyelid. And the division of face, eye, AND EAR. '1J21 the orbicularis oculi into two, by the older anatomists, was a consequence of their not knowing of the true levator palpebral, and their not being able to describe any muscle by which the upper eyelid could be raised, except the upper half of the orbicularis. The occipito-frontalis, but especially its occipital belly, raises the eyebrows ; the pointed slip of "fie same muscle pulls them downwards ; the corrugator pulls them directly in- wards, and knits the brows; the levator palpebral opens the eyelid; and the orbicularis oculi closes the eye. Whether certain fibres from the platisma-myoides (a thin flat muscle which mounts from the neck over the cheek) may not pull down the lower eyelid ; or whether some straggling fibres, arising from the zygoma, may not have the appearance of a depressor of the lower eyelid, it is not necessary to determine, since there is no regularly appointed muscle ; and the lower eyelid is almost immoveable, at least in man. muscles of the nose and mouth. V. Levator labii superioris et al^e nasi. Cowper describes the levator labii superioris as an irregular production of the frontalis, extending along the nostrils. But it is a neat and delicate muscle, which arises, by a small double tendon, from the nasal process of the upper jaw-bone, close by the ten- don of the orbicularis oculi. It is one little fasciculus of mus- cular fibres above ; but as it approaches the nose, it spreads out broader, dividing into two small fasciculi; one of which is implanted into the wing or cartilage of the nose, and the other, passing the angle of the nose, goes to the upper lip. Thus it is pyramidal with its base downwards, and was named pyrami- dalis by Caserius, Winslow, and others. It is called by Cow- per dilator alae nasi. It raises the upper lip, and spreads the nostrils wide, as is observed in a paroxysm of rage, or in asthmatics. VI. The levator labii superioris proprius, is distin- guished by the name of levator proprius, because there are two others ; one belonging to the angle of the mouth, and conse- quendy to both lips ; and one common to the lip and nostril. The levator proprius is often named musculus incisivus, because it arises from the upper jaw, just above the incisores or cutting teeth, and consequently just under the edge of the orbit : it is broad at its origin ; it lies flat, and runs down- wards, and obliquely inwards, to the middle of the lip, till it Vol. J. Q 122 .MUSCLES OF THE meets its fellow just in the filtrum*. It pulls the upper lip and the septum of the nose directly upwards. VII. The levator anguli oris, is called also levator communis labiorum, because it operates equally on both lips. It is named caninus ; for as the last named muscle rises from the upper jaw-bone above the incisores or cutting teeth, this arises above the canini or dog teeth, or above the first grinder, by a very short double tendon. The exact place of its origin is half-way betwixt the first grinder and the infra orbitary hole: it is mixed with the orbicularis oris, at the corner of the mouth, so that it raises the angle of the mouth upwards. VIII. The zygomaticus major has nearly the same direc- tion and use with this one : for it arises from the cheek-bone near the zygomatic suture ; runs downwards and inwards to the corner of the mouth; is a long and slender muscle, which ends by mixing its fibres with the orbicularis oris and the de- pressor of the lip. IX. The zygomaticus minor arises a little higher upon the cheek-bone, but nearer the nose ; it is much slenderer than the last, and is often wanting. It is the zygomatic muscle that marks the face with that line which extends from the cheek-bone to the corner of the mouth, and which is so strong in many. The zygomatic muscles pull the angles of the mouth upwards as in laughter ; or distort the mouth ; whence the zygomatic muscle has gotten the name of distortor oris ; and the strong action of the muscle is particu- larly seen in laughter, rage, grinning. X. Buccinator. The buccinator was long thought to be a muscle of the lower jaw, arising from the upper alveoli, and inserted into the lower alveoli to pull the jaw upwards; but its origin and insertion, and the direction of its fibres, are quite the reverse of this. For this large flat muscle, which forms, in a manner, the walls of the cheek, arises chiefly from the coronoid process of the lower jaw-bone, and partly also from the end of the alveoli or socket process of the upper jaw, close by the pterygoid process of the sphenoid bone : it goes forwards with direct fibres to be implanted into the comer of the mouth : it is thin and flat, covers in the mouth, and forms the walls of the cheek, and is perforated in the middle of the cheek by the duct of the parotid gland. These are its princi- pal uses: that it flattens the cheek, and so assists in swallowing liquids : that it turns, or helps to turn, the morsel in the mouth • The filtrum is the superficial gutter along the upper Up from the partition of the nose to the tip of the lip. r FACE, EYE, AND EAR. }23 while chewing, and prevents it from getting without the line of the teeth : in blowing wind instruments, it both receives and expels the wind: it dilates like a bag, so as to receive the wind in the cheeks ; and it contracts upon the wind, so as to expel the wind, and to swell the note. In blowing the strong wind instruments, we cannot blow from the lungs, for it stresses the breathing, but reserve the air in the mouth, which we keep continually full; and from this it is named, from blowing the trumpet, the buccinator. XI. Depressor angulioris.—The depressor anguli oris is a neat small triangular muscle, and is indeed very commonly named musculus triangularis labiobum, from its shape. The base of the triangle is at the line of the lower jaw, where the muscle rises with a flat fleshy head about an inch in breadth. It grows smaller gradually as it rises towards the corner of the mouth, where it is implanted, small, almost in a point, and directly opposite to the zygomatic and levator muscles ; and as the zygomatic muscle makes a line from the cheek down to the angle of the mouth, this makes a line from the chin up to the corner of the mouth. It is chiefly active in expressing the passions, and gives form to the chin and mouth. In cheerful motions, as laughter, smiling, &c. the zygomatics and levators pull the angles of the mouth upwards. In fear, hatred, revenge, contempt, and the angry passions, the trian- gulares pull the corners of the mouth downwards. And, at the place where these meet, there is formed a sort of rising at the angle of the mouth : for a great many tendons are crowded into diis one point; the zygomatic levator, depressor, and orbicularis oris muscles meeting and crossing each other at this place. XII. The depressor labii inferioris is a small muscle, the discovery of which Cowper claims for himself. It is a ■small muscle, lying on each side of the chin, which, with its fellow, resembles very much the levators of the upper lip. The depressor labii inferioris arises on each side of the chin, from the lower jaw-bone, under the line of the triangular muscle. It goes obliquely upwards and inwards, till it meets its fellow in the middle of the lip ; and where the muscles of the opposite side meet, there is a little filtrum or furrow on the lower lip, as on the upper one. It mixes its fibres with the orbicularis, and its use is to pull the lip downwards. Each muscle is of a square form, and thence has been often named quadratus gen£, the square muscle of the chin. XIII. The orbicularis oris, or muscle round the mouth, is often named constrictor oris, sphincter, or oscula- i or. It is very regular ; it is an inch in breadth, and con- 124. MUSCLES OF THE stitutes the thickness of the lips : it lies in the red part of the lips, and is of a circular form, surrounding the mouth alter the same manner that the orbicularis oculi encircles the eye. We see a degree of crossing in the fibres at the angles of the mouth, whence it has been considered by many, not as a cir- cular muscle, but as one consisting of two semicircular mus- cles, the semi-orbicularis superior, and semi-orbicula- Ris inferior. Its fixed points are the two angles of the mouth; at that swelling which is formed by the union of the zygomatic triangular, and other muscles : and its chief use is to contract the mouth, and to antagonize the other muscles which I have just described. Often a small slip runs up from the middle of the upper lip to the tip of the nose ; it is the nasalis labii superioris of Albinus ; it lies exactiy in the furrow of the fil- trum, and is occasionally a levator of the upper lip, or a depres- sor of the tip of the nose. These muscles of the nose and lips are not useful merely in expressing the passions ; that is but a secondary and accident- al use, while their great office is to perform those continual movements which breathing, speaking, chewing, swallowing, require. There are muscles for opening the mouth in various directions, which are all antagonized by this one, the orbicu- laris oris. The levator labii superioris, and the depressor labii inferioris, separate the lips, and open the mouth. The levator anguli oris, along with the zygomatic muscles, raises the cheek, and dilates the corners of the mouth. The buccinator pulls the corner of the mouth directly backwards, opening the mouth. The angularis oris also dilates the mouth, pulls the angles of the mouth downwards and backwards, and forms it into a circle, if the others act at the same time ; but the orbi- cularis oris is the largest and strongest (formed, as it were, by the fibres of all these taking a new direction, and turning round the lips), shuts the mouth, and antagonizes them all: and from an opening as wide as the mouth can require, shuts the mouth at pleasure, so closely as to retain the very breath against all the force of the lungs. It is the true antagonist of all the other muscles ; and they and the orbicularis mutually react on each other, in alternately opening and closing the mouth. This phenomenon of the orbicularis muscle dilating to suchawideness, and in an instant closing the mouth again with such perfect accuracy as to retain the breath, puts to nought all the .vain calculations about the contraction of muscles ; as that they can contract no more than one third of their length ; for here is an infinite contraction, such as no process can measure. It is a paralysis of these muscles, that so often occasions a hi- deous distortion of the face ; for when the'one side of the bodv FACE, EYE, AND EAR. 125 falls into palsy, the muscles of one cheek cease to act; the muscles of the other cheek continue to act with their usual de- gree of power. This contraction of the muscles of one cheek excites also the orbicularis oris to act, and so the mouth is pur- sed up, and the lips and angles of the mouth are drawn towards one side. There are some smaller muscles which, lying under these, could not be described without danger of confusion ; as— XIV.TheDEPRESSORLABII SUPERIORIS ET AL/ENASI, which is very small, and lies concealed under the other muscles. It rises from the gum or socket of the fore teeth, and .thence is named by Winslow incisivus medius. It goes into the rising of the nose, and pulls it, and of course the upper lip, down ; and is named by Albinus and Cowper constrictor vel compres- sor ala nasi. XV. The constrictor nasi, or compressor of the nose, is a small scattered bundle of muscular fibres, which crosses the wings, and goes to the very point of the nose ; for one arises from the wing of the nose on each side, and meets its fellow in the middle ridge, where both are fixed into the middle cartil- age, or into the lower point of the nasal bones ; meeting with the peak of the frontal muscle, or its scattered fibres. But this muscle is so difficultly found, that when Cowper saw it distinctly marked in Bidloe's 12th table, he considered it as a fiction, having sought for it very carefully, but in vain. And XVI. The levator menti, which arises from the lower jaw, at the root of the cutting teeth, has, been- named incisivus inferior. It is inserted into the skin, on the very centre of the chin : by its contraction it draws the centre of the chin into a dimple ; and from its moving under the lip at the same time, it is named levator labii inferioris. MUSCLES OF THE EXTERNAL EAR. Though perhaps not one often thousand has the power of moving the outward ear, yet there are many thin and scattered fibres of muscles about the root of the cartilage of the ear, to which we cannot refuse the name and distinction of muscles ; and which servo, indeed, to indicate, that nature had intended a degree of motion, which, perhaps by the manner of covering the heads of children, we may have lost. But in a few these fasciculi of fibres have not the form only, but the uses also, of muscles. The celebrated Mr. Mery was wont, when lectur- ingonthis subject, to amuse his pupils, saying, pleasantly," that '* in one thing, he surely belonged to the long-eared tribe ;u •126 MUSCLES OF THE upon which he moved his ears very rapidly backwards and forwards.* XVII. Superior auris is named attollens, because it lifts the ear upwards : it is a very thin, flat, expansion, which can hardly be distinguished from the fascia of the temporal muscles, upon which it lies ; it arises broad and circular from the expanded tendon of the occipito-frontalis, and is inserted narrow into the root of the cartilaginous tube of the ear. XVIII. Anterior auris is a very delicate, thin, and nar- row expansion ; arising about the zygoma, or rather from the fascia with which the zygoma is covered; it is implanted round the cartilaginous tube, at its rootf. XIX. The posterior auris is also a small muscle, very de- licate and thin ; but the anterior rises in one small and narrow slip only, while this, the posterior, rises commonly in three narrow and distinct slips, from about the place of the mastoid process:}:; whence it is often named triceps auris. It goes directly forwards to be implanted into the concha. It is named retrahens auris from its office. But there are still other muscles enumerated, which are not for moving the outward ear upon the head, but for moving or rather bending, the individual parts of the ear upon each other. Those fibres, which are misnamed muscles, are merely mus- cular membranes, which have none of the marks nor offices of true muscles ; they have seldom fleshy fibres, and the parts up- on which they lie are fixed. Heister denies them the title of muscles, and.calls them muscular membranes only. The ring and other bendings of the outward ear are called helix and antihelix, tragus and antitragus ; and this deter- mines the names of these ambiguous fibres, which are some- times found lying upon these circles of the outward cartilage, just under the skin. XX. The musculus helicis major lies upon the upper or sharp point of the helix, or outward ring. XXI. Helicis minor rises lower than the former, upon the part of the helix. XXII. TheTRAGicus lying upon the concha, and stretching to the tragus. XXIII. The antitragicus lies in the antitragus. XXIV. And, lastly, There is the trans versus auris of Albinus. * Vide Palfin, who was his pupil. The celebrated Albinus could move his ears. f We seldom find an anterior auris, or any thing different from the anterior fibres of the attollens. \ Fibra: cnrna: transversa, a nobisdefcriptse Valsalva. FACE, EYE, AND EAR. 127 MUSCLES OF THE EYEBALL. The eyeball is entirely surrounded by muscles, which turn it in all directions. There is one muscle on either side ; one above, and one below ; these arise from the very bottom of the socket, spread out upon the ball of the eye, and are implanted into its forepart, where the expansions of their colourless tendons form what is called the white of the eye. Now, these four muscles being directly above, below, and on either side of the eye, are called the recti, or straight muscles ; for their pul- ling is from the bottom of the socket. But there are other two muscles which are named the oblique muscles, because they pull from the edges of the socket, and turn the eye obliquely ; for they go in a direction exactly opposite to the recti. The recti come directly forwards from the bottom of the orbit i these go obliquely backwards from the edge of the orbit; one rises from the lower edge of the socket, and goes backwards un- der the eyeball; the other rises indeed, along with the recti, in the bottom of the socket, but it has a cartilaginous pulley on the very edge of the socket at its upper part ; and its small round tendon first runs through this pulley, and then turns down upon the eye, and goes backwards ; so that the straight muscles press down the eyeball deep into the socket, while the oblique muscles bring the eyeball forwards, pulling it outwards from the socket. The truest description of the recti is as of one muscle, since their only variety is that of difference of place, which is expres- sed by the name of each. They all agree in these chief cir- cumstances, that they arise by flat, but small tendons, round the margin of the optic hole, arising from the circle of that hole, or rather from the periosteum there ; and there being one above, one below, and one on either side, they completely surround the optic nerve, and adhere to it. They are neat and delicate muscles, gradually expanding each into a fleshy belly, which surrounds and covers the middle of the ball of the eye. They still go on expanding, till they at last terminate, each in a broad, flat, and very white tendon, which covers all the forepart of the eye, up to the circle of the lucid cornea or window ; and their white and shining tendons form that enamelled-like part which lies behind the coloured circle, which is, from its colour, named the white of the eye, or the tunica albuginea, as if it were absolutely a distinct coat. Now, the only difference in these straight muscles is in res- pect of length ; for the optic nerve enters the eye, not regularly in the centre, but a little towards the inner side, so that the 128 MUSCLES OF THE rectus internus, or muscle nearest the nose, is a little shorter. The rectus externus, or muscle nearest to the temple, is a little longer; while the rectus superior and the rectus interior are nearly of equal length. The uses of these muscles are ex- ceedingly plain. XXV.' The rectus superior, lifting the eye directly up- wards, is named the musculus attollens ; the levator oculi ; or superbus, as expressive of haughtiness and pride. XXVI. And the rectus inferior, which is directly op- posite to it, is named deprimens oculi ; or humilis, as ex- pressing modesty and submission. XXVII. The rectus internus is called adducens, as carrying the eye towards the nose ; or bibitorius, because it directs the eye to the cup. And (XXVIII.) The rectus externus, the outer straight muscle, as it turns the eye away, is named abductor ocult, or indignabundus, expressing anger or scorn. Such is the effect of these muscles, that when they act in succession, they roll the eye ; but if they act all at once, the power of each is balanced by the action of its opposite muscle, and the eye is immovably fixed. So that sometimes in our operations, when the couching needle approaches the eye, fear comes upon the patient, and the eye is fixed by a convulsive action, more firmly than it could be by the instruments, or by the finger; so that the speculum oculi is after such an accident of no use: the eye continues fixed during all the operation, but it is fixed in a most dangerous way, by a power which we cannot con- troul, and which sometimes, when our operation is for ex- tracting one of the humours only, squeezes out the whole. XXIX. The obliquus superior arises along with the recti in the bottom of the eye, above and towards the inner side ; directing its long tendon towards the inner angle of the eye ; and there it passes its tendon through that pulley, whose hol- low I have marked in describing the os frontis, as under the superciliary ridge, and near to the inner comer of the eve. It arises by a small tendon, like one of the recti ; it goes over the upper part of the eyeball, a long and slender muscle, whence it is often named longissimus oculi, the longest muscle of the eye. It forms a small smooth round tendon, which passes through the ring of the cartilaginous pulley, which is in the margin of the socket. The pulley is above the eye, and pro- jects farther than the most prominent part of the eyeball, so that the tendon returns at an acute angle, and bends down- wards before it can touch the eyeball. And it not only returns backwards in a direction opposite to the recti muscles, but it slips flat under the body of the rectus superior, and is spread FACE, eye, AND EAR. 12$ out under it upon the middle, or behind the middle of the eye, viz. about half way betwixt the insertion of the rectus and the entrance of the optic nerves. XXX. The obliquus inferior is, with equal propriety. named the musculus brevissimus oculi. It is directly op- posite to the obliquus superior, in form, place, office, &c.; for it arises from the nasal process of the jaw-bone, in the lower edge of the orbit, at the inner corner of the eye : it is short, flat, and broad, with a strong fleshy belly : it goes ob- liquely backwards and outwards, lying under the ball of the eye ; and it is inserted broad and flat into the ball, exactly op- posite to the insertion of the obliquus superior muscle. These two muscles roll the eye, whence they are named musculi circumagentes, or amatorii. But they have still another important office, viz. supporting the eyeball, for the operation of its straight muscles ; for when these (the obliqui) act, they pull the eye forwards ; the straight muscles resist; and the insertion of the oblique muscles at the middle of the eyeball becomes, as it were, a fixed point, a centre or axis round which the eyeball turns under the operation of the recti muscles. The conjoined effect of the oblique muscles is to bring the eyeball forwards from the socket, as in straining the eye to see some distant point. The particular effect of the upper oblique muscle is not to bring the eye forward, but to roll the eye so as to turn the pupil downwards, and towards the nose. And the particular effect of the lower oblique muscle is to reverse this action, to turn the eye again upon its axis, and to direct the pupil upwards and outwards ; but the suc- cessive actions of all these muscles move the eye in circles, with gradations so exquisitely small, and with such curious combinations as cannot be explained by words. Vol. I. n ( 130 ) CHAP. II. MUSCLES OF THE LOWER JAW, THROAT, AND TONGUE. muscles of the lower jaw. X HE lower jaw requires muscles of great power to grind the food ; and accordingly it is pulled upwards by the strong temporal, masseter, and pterygoid muscles. But in moving downwards, the jaw almost falls by its own weight; and hav- ing little resistance to overcome, any regular appointment of muscles for pulling down the jaw is so little needed, that it is pulled downwards by muscles of such ambiguous office, that they are equally employed in raising the throat, or pulling down the jaw, so that we hardly can determine to which they belong ; for the chief muscles of the throat, coming from the lower jaw, must, when the jaw is fixed, pull up the throat; or, when the throat is fixed, depress the jaw. XXX. The temporal muscle is the great muscle of the jaw. It arises from all the flat side of the parietal bone, and from the sphenoid, temporal, and frontal bones, in that hollow behind the eye where they meet to form the squamous suture. It arises also from the inner surface of that strong tendinous membrane which is extended from the jugum to the semicircu- lar ridge of the parietal bone. The fibres are bundled to- gether and pressed into a small compass, so that they may pass under the jugum ; there they take a new hold upon the inner surface of the jugum, and the muscle is of course pyramidal, its rays converging towards the jugum. Its muscular fibres are intermixed with strong tendinous ones ; it is particularly tendinous where it passes under the jugum ; and it has both strength and protection from that tendinous plate which covers it in the temple. Its insertion is into the hom of the lower jaw-bone ; not merely into the tip of the hom, but embracing it all round, and down the whole length of the process, so as to take the firmest hold. XXXI. The masseter is a short, thick, and fleshy muscle, which gives the rounding of the cheek at its back part. It arises from the upper jaw-bone, at the back of the antrum, and under the cheek-bone, and from the lower edge of the MUSCLES OF THE, &C. 131 zygoma. It lies upon the outside of the coronoid process, covering the branch of the jaw quite down to its angle. It is particularly strong; has many massy bundles of flesh, inter- spersed with tendinous strings; the parotid gland lies on its upper part, and the duct of the gland (as it crosses the cheek) lies over this muscle. The jaw is very firmly pulled up by these two, which are its most powerful muscles ; and when we bite, we can feel the temporal muscle swelling on the flat part of the temple, and this the masseter upon the back part of the cheek. XXXII. XXXIII. The two pterygoid muscles (of which there are four in all, two on either side) are named from their origin in the pterygoid processes of the sphenoid bone. The pterygoideus internus is that one which rises from the in- ternal or flatter pterygoid process, and which goes downwards and outwards to the angle of the jaw on its inside. The pterygoideus externus arises from the external pteiygoid process ; and goes not downwards, but almost directly out- wards, and is implanted high in the jaw-bone, just under its neck, and connected with its capsular ligament. Now the pterygoideus internus descending to be fixed to the angle of the jaw, is longer and bigger, and is named pterygoideus ma- jor. The internal one going directly across, and rather back- wards, has less space to traverse, is shorter, and is named pterygoideus minor. The jaw is moved chiefly by these muscles ; the temporalis acting upon the coronoid process like a lever; the masseter acting upon the angle, and before it; and the pterygoideus internus balancing it within, like an internal masseter fixed to the inside of the angle. All these pull strongly upwards for biting, holding, and tearing with the teeth. And the external or lesser pterygoid muscle going from within outwards, pulls the jaw from side to side, and performs all the motions of chewing and grinding, z. e. of rotation, so far as the lower jaw possesses that kind of motion. MUSCLES OF THE THROAT AND TONGUE. The muscles of the throat and tongue cannot be under- stood without a previous acquaintance with certain cartilages and bones, which form the basis of the throat and tongue, and the centre of those motions which we have next to describe. The os hyoides is a small bone resembling, in shape at least, the jaw-bone. It has a middle thicker part, named its basis, which is easily felt outwardly ; it corresponds in place 132 MUSCLES of the with the chin, and is distinguished about an inch below the, chin ; the uppermost of the hard points which are felt in the forepart of the throat. Next, it has two long horn-like pro- cesses, which go backwards along the sides of the throat, cal- led the cornua, or horns of the os hyoides ; and which are tied by a long ligament, which comes down from the styloid process of the temporal bone. And, lastly, It has small cartilaginous pieces or joinings, by which the horns are united to the basis ; and often in the adult this joining is converted into bone. At this point where the two homs go backwards, like the legs of the letter V, there are commonly at the gristly part of the os hyoides two small perpendicular processes, Which stand up from the joining of the horns to the body; and these are named the appendices of the os hyoides or die lesser cornua. Now this os hyoides forms by its basis the root of the tongue; thence it is often named the bone of the tongue. It forms at the same time the upper part of the trachea, or wind- pipe ; and it carries upon it that cartilage named epiglottis, which, like a valve, prevents any thing getting down into the windpipe. Its horns extend along the sides of the throaty keeping the openings of the windpipe and gullet extended as we would keep a bag extended by two fingers. The chief muscles of the tongue and of the windpipe arise from its body; the chief muscles of the gullet arise from its horns, and espe- cially from their points; it receives the chief muscles which either raise or depress the throat; and it is the point d'appui, or fulcrum for all the muscles of the throat and tongue, and the centre of all their motions. It is the centre of the motions of the tongue ; for it is the origin of these muscles which com- pose chiefly the bulk of the tongue; of the motions of the trachea or windpipe, for it forms at once the top of the wind- pipe, and the root of the tongue, and joins them together; of the motions of the pharynx or gullet, for its horns surround the upper part of the gullet, and join it to the windpipe ; and it forms the centre for all the motions of the throat in general, for muscles come down from the chin to the os hyoides, to move the whole throat upwards; others come up from the sternum, to move the throat downwards ; others come ob- liquely from the coracoid process of the shoulder-blade, to move the throat backwards, while the os hyoides still continues the centre of all these motions. • The trachea, or windpipe, is that tube which conveys the air to the lungs ; and the larynx is the head, or figured part of that tube which is- formed like a flute for the modula- tion of the voice, and consists of cartilages, that it may stand lower jaw, throat, AND TONGUE. 133 firm and uncompressed, either by the passage of the food, or by the weight of the outward air; and that it may resist the contraction of the surrounding parts, serving as a fulcrum for them in the motions of the jaw, tongue, and gullet. Its carti- lages are, first, the scutiform, or thyroid cartilage, which is named from its resemblance to a shield, or rather it is like the flood-gates or folding doors of a canal, the meeting of the two sides being in the middle line of the throat. This prominent Hne of the thyroid cartilage is easily felt in the middle of the throat; is about an inch in length, and makes that tumour which is called the pomum Adami. The flat sides of the thy- roid cartilage form the sides of the flute part of the trachea. And there are two long horns at its two upper corners, which rise like hooks above the line of the cartilage, and are joined to the horns of the os hyoides; and two similar, but shorter hooks below, by which it embraces the cricoid cartilage. The cricoid cartilage is next to the thyroid, and below it; it is named from its resemblance to a ring: it is indeed like a ring or hoop, but it is not a hoop equally deep in all its parts, it is shallow before, where it ekes out the length of the thyroid cartilage, and is deeper behind, where it forms the back of this flute-like top of the trachea; it is the top ring of the trachea, and the lower ring of the larynx or flute part of the windpipe. And upon its back, or deeper part, are seated those two small cartilages, which form the opening for the breath. The arytenoid cartilages are two small bodies, of the size of peas. They are foolishly described with cornua, ridg- es, and surfaces, when they are so small that nothing further can be observed of their forms than that they are somewhat triangular ; that the base or broad part of each sits down upon the upper edge of the cricoid cartilage at its back ; that the point of each stands directly upwards, and is a very little crook- ed, or hook-like, that standing, as they do, a little apart from each other, they form together an opening something like the spout of a ewer, or strouped basin, whence their name. And these cartilages being covered with the common membrane of the throat, which is thick, and full of mucous glands, the open- ing gets a regular appearance with rounded lips; and this opening, or slit between them, which is something like the slit for the thill in the top of a counter, and which slants obliquely downwards, is named the rima glottidis, or chink of the glottis ; and these cartilages'being fixed on the cricoid carti- lage by a regular hinge, they form the voice by their nearness and the narrowness of the slit; and modify it by their motions, which are so exquisitely minute, that for every changing of the note (and there are some thousand gradations in the compass of the voice), they move in a proportional decree. 131 MUSCLES OF THE The epiglottis is a fifth cartilage of the trachea, belong. ing to it both by connection and by office. It is a broad trian- gular cartilage, not so hard as the others, very elastic, and so exactly like an artichoke leaf, that no other figure can represent it so well. Its office is to defend the opening of the glottis. It is fixed at once to the os hyoides, to the thyroid cartilage, and to the root of the tongue, and it hangs obliquely backwards over the opening of the rima, or chink, of the glottis ; it is sus- pended by little peaks of the membrane, which we call liga- ments of the glottis, and it is said to be raised or depressed by muscles, which yet are not very fairly described. But the rolling of the morsel which is swallowed, and the motion of the tongue, are sufficient to lay it flat over the rima, so that it is a perfect guard. Then this is the constitution of the larynx. It is of hard cartilages to resist compression, and of a flute form at its open- ing, to regulate the voice. The thyroid cartilage is the great one, the chief defence before, and which has edges slanting far backwards, to defend the opening of the larynx. The cricoid cartilage, which forms the upper ring of the trachea, supports the arytenoid cartilages, and by its deepness behind, raises them so that the opening of the glottis is behind the middle of the great thyroid cartilage, and in the deepest part of it, well defended by its projecting wings. The arytenoid cartilages form the rima glottidis, the chink by which we breathe (which, as it is narrower or wider, modulates and tunes the voice), the opening which is so exquisitely moved by its muscles in sing- ing ; widening or contracting in most delicate degrees ; and which is so spasmodically shut by the same muscles when it is touched by a drop of water, or by a crumb of bread: but the valve of the glottis, the epiglottis standing over it, flaps down like the key of a wind instrument, so that the rareness of such accidents is wonderful, when we consider that the least attempt to draw the breath, while we are swallowing, will produce the accident. The muscles which move the tongue and throat must be far too complicated to be explained at all, without some previous knowledge of these parts ; and still, I fear, not easily to be explained with every help of regularity and order. MUSCLES OF THE THROAT. By this arrangement, I mean to include under one class all those muscles which move the os hyoides, or the larynx ; and through diese, as centrical points, the jaws, gullet, and LOWER JAW, THROAT, AND TONGUE. 135 tongue ; and which, though they are inserted into the larynx ; have more relation to swallowing, or the motions of the gul- let, than to breathing, or to the motions of the windpipe. The muscles which pull the throat down are these : XXXIV. The sterno-hyoideus, which passes from the sternum to the os hyoides ; a flat broad riband-like muscle, which arises from the upper piece of the sternum, rather within the breast; and partly also from the calvicle and carti- lage of the first rib ; goes flat and smooth along the forepart of the throat; mounts, nearly of the same breadth, to the os hyoides ; and is implanted into its basis, or that part (which in resembling the os hyoides to the jaw) we should compare with the chin. XXXV. The sterno-thyroideus, which passes in like manner from the sternum to the thyroid cartilage, is like the last, a flat smooth riband-like muscle ; rather thicker and more fleshy, but very uniform in its thickness. As the thyroid cartilage is below the os hyoides, the sterno-thyroid muscle must lie under the sterno-hyoideus muscle. It arises under the sterno-hyoideus muscle from the sternum and cartilage of the rib ; and is implanted into the rough line of the lower edge of the thyroid cartilage, and a little to one side, but not so much as is represented in Cowper's drawings. It immediately covers the thyroid gland ; and the way to the trachea for pier- cing it in performing bronchotomy is in the middle betwixt these muscles. XXXVI. The omo-hyoideus, which was once named coraco-hyoideus being thought to arise from the coracoid process. It is a muscle of great length, and very slender, reaching from the shoulder to the os hyoides ; it is like these last mentioned, a long flat, strap-like muscle ; as flat and as fleshy, but not so broad, as either of the former. It lies along the side of the neck ; is pinched in a little in the middle, where it is divided by a tendinous cross line, which separates the fleshy belly into two heads. It arises from the upper edge of the scapula, near its notch, and is implanted into the side of the os hyoides, where the horn goes off from the body of the bone. These three muscles pull the throat down. The sterno- hyoideus and sterno-thyroideus pull it directly downwards : one of the omo-hyoidei acting, pulls it to one side ; f>ut if both act, they assist in pulling directly down, and they brace the trachea at the same time a little down to the back. The muscles which move the throat upward, are : XXXVII. The mylo-hyoideus, a flat and broad muscle, which arises from the whole semicircle of the lower jaw, i. c. 136 MUSCLES OF THE from the backmost grinders to the point of the chin. It rises from the inner surface of the jaw-bone ; goes down to the basis of the os hyoides ; proceeds with very regular, straigh^ clear, and orderly fibres, from the jaw to the os hyoides ; is plainly divided in the middle from the symphysis of the jaw to the middle of the os hyoides, by a middle tendinous and white line. And though Cowper denies the authority of Vesalius, who divides it thus, it is plainly two distinct mus- cles, one belonging to either side. XXXVIII. The genio-hyoideus is a small neat pair of muscles arising from the chin at a rough point, which is easily distinguished within the circle of the jaw. The mylo-hyoi- deus is named from the whole jaw. The genio-hyoideus is named from the chin, arising from a small tubercle behind the chin ; its beginning is exceedingly narrow : as it proceeds downwards, it grows flat and broad ; it is implanted into the basis of the os hyoides by a broad edge, and is a beautiful and radiated muscle. The sublingual gland lies flat betwixt this muscle and the last; and in the middle the sublingual duct pierces the membrane of the mouth, to open under the root of the tongue. The two muscles move the os hyoides forwards and upwards, when the jaw is fixed ; but when the os hyoid€s is fixed by the muscles coming from the sternum, these mus- cles of the os hyoides pull the jaw down. XXXIX. The stylo-hyoideus is one of three beautiful and slender muscles, which come from round the styloid process; which all begin and end with slender tendons, and with small fleshy bellies ; and one going to the phaiynx or gullet, another to the os hyoides, and a third to the tongue, they coincide in one common action of drawing back the tongue, and pulling the throat upwards. This one, the stylo-hyoideus, arises from about the middle of the styloid process, and going obliquely downwards and for- wards, is fixed into the side of the os hyoides, where the basis and horn are joined. Above its insertion, its fibres are split, so as to make a neat small loop, through which the tendon of the digastric muscle runs. This stylo-hyoideus is sometimes accompanied with another small fleshy muscle like it, and of the same name ; which was first perhaps observed by Cowper, and has been named by Innes stylo-hyoideus alter ; but it is not regular, nor has it ever been acknowledged as a distinct muscle. XL. The digastricus, or biventer maxilla inferioris, is named from its having two bellies. One belly arises from a rugged notch along the root of the mastoid process, where the flesh is thick and strong: going obliquely forwards and down- LOWER JAW, THROAT, AND TONGUE. 137 wards, it forms a long tendon, round, thick, and very strong, which passes by the side of the os hyoides ; and as it passes, it first slips through the loop or noose of the stylo-hyoideus, and then is fixed by a tendinous bridle to the side of the os hyoides j and then turning upwards towards the chin, it ends in a second fleshy belly, which, like the first, is flat, and of a pyramidal shape, lying above the mylo-hyoideus. Though this muscle is often called biventer maxilla inferio- ris, as belonging to the lower jaw, perhaps it does more regu- larly belong to the throat. No doubt, when the os hyoides is fixed by its own muscles from the shoulder and sternum, the digastricus must act on the jaw ; an office which we cannot doubt, since we often feel it taking a sudden spasm, pulling down the chin with severe pain and distortion of the neck. But its chief office is to raise the os hyoides ; for when the jaw is fixed, as in swallowing, the raising of the os hyoides pulls up the throat; and this is the true meaning of its passing through the noose of the stylo-hyoideus, and of its connexion with the side of the os hyoides. Then the digastric and stylo- hyoideus muscles pull the throat upwards and backwards. The muscles which move the parts of the larynx upon each other are much smaller, and many of them very minute. XLI. The hyo-thyroideus goes down, fleshy and short, from the os hyoides, to the thyroid cartilage. It arises from the lower border of the thyroid cartilage, where the sterno- thyroideus terminates, and goes up along the side of the thy- roid cartilage, like a continuation of the sterno-thyroideus mus- cles. It passes the upper border of the thyroid cartilage, and is fixed to the lower edge of the os hyoides, along both its base and part of its horn. XLII. The crico-thyroideus is a very short muscle, passing from the upper edge of the cricoid to the lower margin of the thyroid cartilage, chiefly at its side, and partly attached to its lower horn ; which comes down clasping the side of the cricoid ring, so that it is broader above, and a little pointed below. These two small muscles must have their use, and they bring the thyroid cartilage nearer to the os hyoides, and the cricoid nearer to the thyroid cartilage; and by thus shortening the trachea, or compressing it slighdy, they may perhaps affect the voice. But the muscles on which the voice chiefly de- pends, are those of the rima glottidis ; for there is a double set of muscles for the little arytenoid cartilages ; one set which brings the cartilages together, and another set which draws them apart, and spreads the opening of the lanmx. XLIII. The musculus arytenoideus transversa is Vo*. I. S 138 MUSCLES OF THE that delicate muscle which contracts the glottis, by drawing the arytenoid cartilages towards each other. It lies across, betwixt them, at their back part ; it arises from the whole length of one arytenoid cartilage to go across, and be inserted into the whole length of the opposite one. XLIV. Arytenoideus obliquus, is one which crosses in a more oblique direction, arising at the root of each arytenoid cartilage, and going obliquely upwards to the point of the op- posite one. These two muscles draw the arytenoid cartilages together, and close the rima. XLV. The crico arytenoideus posticus, is a small pyramidal muscle, which arises broader from the back part of the cricoid cartilage, where the ring is broad and deep ; and going directly upwards, is implanted with a narrow point into the back of the arytenoid cartilage. This pair of muscles pulls the arytenoid cartilages directly backwards, and lengthens the slit of the glottis. XLVI. The crico arytenoideus obliquus, is one which comes from the sides of the cricoid cartilage, where it lies un- der the wing of the thyroid, and being implanted into the sides of the arytenoid cartilages, near their roots, must pull these cartilages asunder, and (as the origin in the cricoid lies rather before their insertion in the arytenoid cartilages) it must also slacken the lips of the slit; for the lips of the slit are formed by two cords, which go within the covering membrane, from the tip of each cartilage to the back of the thyroid carti- lage ; and the crico arytenoideus posticus must strengthen these cords, and the crico arytenoideus lateralis must relax them. XL VII. The thyreo arytenoideus, is a muscle very like the last one, and assists it. It arises not from the cricoid carti- lage, but from the back surface of the wing of the thyroid; from the hollow of its wing, or where it covers the cricoid; is implanted into the forepart of the arytenoid cartilage, and by pulling the cartilage forward and sidewise, directly slackens the ligaments and widens the glottis. These are all the muscles which belong to the larynx; and in our arrangement the muscles of the palate and pharynx come next in order. When a morsel is to be thrown down into the oesophagus, or tube which leads to the stomach, the velum palati, or cur- tain of the palate, is drawn upwards ; the opening of the throat is dilated ; the morsel is received ; then the curtain of the palate falls down again.* The arch of the throat is con- tracted, the bag of the pharynx is compressed by its own mus- cles j and the food is forced downwards into the stomach. LOWER JAW, THROAT, AND TONGUE, 139 XLVIII. The azygos uvulae,—The velum pendulum palati, is that pendulous curtain which we see hanging in the back part of the mouth, in a line with the side circles of the throat; and the uvula is a small pap, or point of flesh, in the centre of that curtain. The azygos uvul£, or single muscle of the uvula, is a small slip of straight fibres, which goes di- rectly down to the uvula in the centre of the curtain. It arises from the peak, or backmost sharp point of the palate bones, and pulls the uvula, or pap of the throat, directly upwards, removing it out of the way of the morsel which is to pass. XLIX. Levator palati mollis arises from the point of the os petrosum, and from the eustachian tube, and also from the sphenoid bone*. These parts hang over the roof of the velum, and are much higher than it; so this muscle de- scends to the velum, and spreads out in it; and its office is to pull up the velum, to remove it from being in the way of the morsel, which is about to pass, and to lay the curtain back at the same time, so as to be a valve for the nostrils, and for the mouth of v the eustachian tube, hindering* the food or drink from entering into these passages. L. The circumflexus palatij, and the constrictor . isthmi fauscium, have a very different use. The«cir%urR- flexus palati is named from its fibres passing over, or rather under, the hook of the pterygoid process ; the muscle arises along with the levator palati (i. e.) from the sphenoid bone at its spinous process ; and from the beginning of the eustachian tube, it runs down along the tube, in the hollow betwixt the pterygoid processes ; it then becomes tendinous, turns under the hook of the internal pterygoid process, and mounts again to the side of the velum. Now, the levator and circumflexus arise from the same points ; but the levator goes direcdy downwards into the velum, and so is useful in lifting it up. The circumflexus goes round the hook ; runs on it as on a pully ; turns upwards again ; and so it pulls down the palate, and stretches it: and thence is very commonly named, the tensor palati mollis, or stretcher of the palate. * From the eustachian tube, it was named salpingo staphilinds; from the sphenoid bone, spheno-staphil-inus ; from the pterygoid process, pterygo- .tapuilinus ; from the petrous process, it was named petro-salpingo-sta- philcnus ; as if there were no science but where there were hard names, and,as if the chief mark of genius were enriching the hardest names, with all possible combinations and contortions of them. f This also has got a tolerable assortment of hard names; as circumflexus PALATI, TENSOR PALATI, PALATO-SALPINGUS, STAPHIL1NUS EXTERNUS, SPHENO SALPINGO-STAPHILINUS, MUSCULUS, TUB.I, VIZ. EUSTATINJE NONU^S. Pterygo-stapiiilinus of Cowper, &c. 140 MUSCLES of THE LI. The constrictor isthmi fauscium, arises from the Very root of the tongue on each side ; goes round to the mid- dle of the velum, and ends near the uvula*. This semicircle forms that first arch which presents itself upon looking into the mouth. LII. The PALATO-PHARYNGEUsf, again, forms a second arch behind the first; for it begins in the middle of the soft pal- ate; goes round the entry of the fauces, ends in the wing or edge of the thyroid cartilage ; and as the first arched line (that formed by the constrictor) belonged to the root of the tongue, this second arched line belongs to the pharynx or gullet. The circumflexus palati makes the curtain of the palate tense, and pulls it downwards: the constrictor fauscium helps to pull down the curtain, and raises the root of the tongue to meet it: The palato-pharyngeus farther contracts the arch of the fauces, which is almost shut upon the morsel now ready to be forced down into the stomach, by those muscles which compress the pharynx itself. The pharynx, which is the opening of the gullet, that it may receive freely the morsel of food, is expanded into a large and capacious bag, which hangs from the basis of the skull, is chiefly attached to the occipital bone, the pterygoid processes, and the back parts of either jaw-bone. The oesophagus, again, is the tube which conveys the food down into the stomach; and this bag of the pharynx is the expanded or trumpet-like end of it; or it may be compared with the mouth of a funnel. Towards the mouth, the pharynx is bounded by the root of the tongue and by the arches of the throat; behind, it lies flat and smooth along the bodies of the vertebrae; before, it is protected, and in some degree surrounded, by the great cartilages of the larynx; the horns of the os hyoides embrace its sides, and it is covered with flat muscular fibres, which, arising from the os hyoides and cartilages of the throat, go round the pharynx, in fair and regular orders, and are named its constrictors, because they embrace it closely, and their contractions force down the food. LIII. The stylo-pharyngeus, arises from the root of the styloid process. It is a long, slender, and beautiful muscle; it expands fleshy upon the side of the pharynx; extends so far as to take a hold upon the edge of the thyroid cartilage ; it lifts the pharynx up to receive the morsel, and then straitens and com- • Named olosso-staphilinus, from its origin in the tongue, and insertion into the uvula. f ThesALPiNGo-PHARYNGEUs of Albinus, is no more than that part of the pajato-pharyngeus which arises from the mouth of the eustachian tubef LOWER JAW, THROAT, AND TONGUE. V*l presses the bag, to push the morsel down, and by its hold upon the thyroid cartilage it commands the larynx also, and the whole throat. The pharynx being surrounded by many irregular points of bone, its circular fibres or constrictors have many irregular ori- gins. The constrictor might fairly enough be explained as one muscle, but the irregular origins split the fibres of the muscle, and give occasion of dividing the constrictor into distinct parts; for one bundle arising from the occipital bone and os petrosum from the tongue, the pterygoid process, and the two jaw bones, is distinguished as one muscle, the constrictor superior*.— Another bundle arising from the os hyoides, is named the con- strictor mediusf. A third bundle, the lowest of the three, ari- sing from the thyroid and cricoid cartilages, is named the con- strictor inferior^. LIV. The constrictor superior, arising from the basis of the skull, from the jaws, from the palate, and from the root of the tongue, surrounds the upper part of the pharynx; and it is not one circular muscle, but two muscles divided in the mid- dle line behind, by a distinct rapha, seam, or meeting of the op- posite fibres. L V. The constrictor medius rises chiefly from the round point in which the os hyoides terminates; it also arises from the cartilage of the os hyoides (i. e.) where the horns are joined to the body. The tip of the horn being the most prominent point, and the centre of this muscle, it goes upwards and downwards, so as to have something of a lozenge-like shape; it lies over the upper constrictor like a second layer; its uppermost peak or pointed part touches the occipital bone, and its lower point is hidden by the next muscle. LVI. The constrictor inferior arises partly from the thyroid, and partly from the cricoid cartilage; and it again goes also obliquely, so as to overlap or cover the lower part of the constrictor medius. This, like the other two constrictors, meets its fellow in a tendinous middle line; and so the morsel admitted into the pharynx by the dilatation of its arches, is pushed down into the oesophagus by the forces of these constric- tores pharyngis, assisted by its styloid muscles. LVII. The cesophagus is merely the continuation of the * These good opportunities of names have not been disregarded: this muscle has been named cephalo-pharyngeus, pterigo-puaryngeus, mylo-pha- ryngeus, glosso-pharyngeus. f This one is named uyo-pharyngeus, or syndesmo-pharyngeus, from its origin in the cartilage also of the os hyoides. • This, of course, is named thyro-pharyngeus, and crico-puarynoeus. 142 MUSCLES OF the, &c. same tube. It lies flat upon the back-bone, and it is covered in its whole length by a muscular coat, which is formed, not like this of the pharynx, of circular fibres, but of fibres running according to its length chiefly. And this muscle surrounding the membraneous tube of the oesophagus like a sheath, is nam- ed TAGINALIS GULjE. MUSCLES OF THE TONGUE. The muscles of the tongue are large bundles of flesh which come from the os hyoides, the chin, and the styloid process. Their thickness constitutes the chief bulk of the tongue. Their actions perform all its motions. The muscles, which I am now to describe, form the whole flesh of the tongue, excepting merely the thin membranes which cover the tongue, and give it form, and conduct its nerves to the papillae or feeling points. L VIII. The first muscle of the tongue is the stylo-gloss- us, which arises from the styloid process, goes obliquely down- wards and forwards; it touches the tongue a little before the angle of the tongue ; it makes part of the flesh at the side of the tongue, expanding into its substance in somewhat of a radiat- ed form; its office is to pull the tongue backwards into the mouth. LIX. The hyo-glossus is a comprehensive name for all those muscles which arise from the os hyoides. The muscles from the os hyoides go off in three fasciculi, and were once reckoned as distinct muscles. That the portion which arises from the basis of the os hyoides, was called basio-glossus ; that which arises from the cartilaginous joining of the body and horn, was called chondro-glossus ; and that which arises from the horn itself, was named cer ato-glossus ; or the terms were all bundled together into the perplexed names ofBASio- chondro cerato-glossus. The hyo-glossus, then, is all that muscular flesh which arises from the whole length of the os hyoides ; and which, by the changing form of the bone in its basis, cartilage, and hom, has slight marks of division, but which lies all in one plain, and need not have distinct names. LX. The genio-glossus arises from the rough tubercle behind the symphysis of the chin. It has a very narrow or pointed origin ; it spreads out fan-like, as it goes towards the tongue; and it spreads with radii, both forwards and back- wards, making the chief part of the substance of the tongue. LXI. The lingualis is an irregular bundle of fibres which runs according to the length of the tongue : it lies betwixt the muscles op the arm, &c* t43T stylo-glossus and the genio-glossus; and as it is in the centre, and unconnected with any bone, it is named lingualis, as arising in the tongue itself. The genio-glossi muscles form by far the larger part of the tongue, and lie in the veiy centre. They go through the whole length, (i. e.) from the root to the tip of the tongue ; and from the radiated form of their fibres, they perform every possible motion ; whence this was named by Winslow, musculus po- kychrestus, for its rays proceed from one point or centre, and those which go to the point of the tongue pull the tongue back- wards into the mouth ; those which go backwards, thrust the tongue out of the mouth ; the middle fibres acting, make the back of the tongue hollow, while the tip and the root of the tongue both rise. The hyo-glossi muscles lie on either side of the genio-hyoi- daei, and make up the sides of the tongue ; and their chief ac- tion would seem to be this, that the hyo-glossus muscle of either side acting, the edges of the tongue would be pulled downwards, and the back rounded ; the opposite of which motion is the genio-hyoidsei acting, by which the middle of the tongue is made into a groove; the edges rising, and the centre being depressed. Lastly, the stylo-glossus is plainly intended N for drawing the tongue deep into the mouth, particularly affect- ing the point of the tongue. CHAP. Ill, OF THE MUSCLES OF THE ARM, including the muscles op the scapula, arm, fore-army AND HAND. muscles of the scapula. JL HE great peculiarity of the arm is the manner of its con- nection with the breast; to which it is fixed by no ligaments, nor joined to no bone, but is at once both fixed and moved by its strong and numerous muscles, which are indeed its only Ii- • 144> muscles of the arm, Sec gaments. Though it were perhaps more regular to describe first the muscles of the trunk, it will be more easy and natural to describe first the broad muscles belonging to the scapula, which cover almost the whole trunk, and hide its proper mus- cles, viz. those which move the ribs and spine. For the mus- cles which move the scapula lie upon the trunk ; those which move the arm lie upon the scapula ; those which move the fore-arm lie upon the arm ; and those for moving the hand and fingers lie upon the fore-arm* The leg requires but one chief motion, viz. backwards and forwards, flexion and exten- sion : it has no other motions than those of the thigh and of the knee. But the arm requires an easy and circular motion ; and its joints are multiplied ; for it has the wrist turning round ; it has the elbow for hinge-like motions ; it has the shoulder- joint upon which the arm rolls ; and to assist all these, the scapula, which is the centre of all these motions, is itself moveable ; after a certain point of elevation all the motion in raising the arm is performed, not by the motions of the shoulder-bone upon the scapula, but by the scapula upon the trunk. For whenever the shoulder-bone rises to the horizon- tal direction, it is checked by the acromion, which hangs over it; and if the arm is to be raised higher still, the scapula must roll ; for it turns as if upon an axis passed through it, and in turning it glides upon those muscles, which are like a cushion betwixt it and the trunk. The muscles which move the scapula come from the breast to move it forwards ; from the neck, to move it upwards; from the spines of the vertebrae, to move it backwards ; and from the side, that is, from the ribs, to move it downwards. LXII. The trapezius is named from its lozenge form; or is often named cucularis, from its resembling the Monk's cowl; hanging back upon the neck. It is one of the most beautiful muscles in the body; and the two muscles together cover all the shoulders and neck, with a lozenge-like form, with neat and sharp points, extending from the tip of one shoulder to the tip of the odier, and from the nape of the neck quite down to the loins. It arises first by a strong tendon from the most pointed part of the occipital bone, and along the transverse spine quite to the mastoid process ; from this point all down the neck it has no hold of the vertebra?, but arises from its fellow in a strong tendon, which, extending like a bow-string down the neck, over the arch of the neck, and not touching the vertebrae till it comes down to the top of the back, is named ligamentum nuch,e. The tendon begins again to take hold of the spines of the two last vertebrae of the neck, and arises from all the spinous processes of the back down- MUSCLES of the arm, &c. 145 wards ; from this long origin, its fibres converge, as it were, into one point, the tip of the shoulder : it also comes a little forward over the side of the neck. It is implanted into one third of the clavicle nearest the shoulder; into the tip of the acromion ; into the whole length of the spine, from which the acromion rises. And its fibres, arising from along the neck and back, and converging almost into a point, must have various effects, according to the dif- ferent fibres which act: for those which come downwards must raise the scapula ; those which come from the middle of the back must carry it directly backwards ; those which come from the lower part of the back must depress it; and those different fibres acting in succession, must make the scapula roll. The trapezius is chiefly a muscle of the scapula, but it must be also occasionally a muscle of the head, pulling the head backwards, and bending the neck. Three other muscles which raise the scapula, or carry it backwards, lie so much in the same plane, and are so little divided from each other, that they might almost be reckoned different portions of the same. LXIII. Levator scapula, named also levator pro- prius angularis, is a small thin slip of flesh, which arises from the four or five uppermost vertebrae of the neck, at their transverse processes, by three or four, and sometimes five, distinct heads. The heads join to form a thin and flat stripe of muscle, about three inches in breadth, which is fixed by a flat thin tendon to the upper corner of the scapula, to pull it upwards, as in shrugging the shoulders ; whence it is named MUSCULUS PATIENTIjE. LXIV. and LXV. The rhomboid muscle stretches flat, neat, and of a square form, betwixt the spine and the whole hne of the base of the scapula. One part arises from the three lower spinous processes of the neck, and is implanted into the base of the scapula at its upper part: then another portion arises from the spinous processes of the first four verte- brae of the back ; runs exactly in the same plane with the other into the base of the scapula at its lower part: the part arising from the three vertebrae of the neck is slightly divided from that which arises from the four vertebrae of the back, though not distinctly, and often not at all. I would reckon this but one muscle, but it has .been commonly distinguished into (LXIV.) the rhomboides minor, the uppermost portion, and (LXV.) the rhomboides major, the lower portion. These are seen after raising the trapezius ; and the uses of the trapezius, levator scapulae, and rhomboides, are to raise the scapula, or to carry it backwards. The muscles which move Vol. I. T 146 muscles op the arm, &c. the scapula downwards and forwards, viz. the pectoralis m?in°r and the serratus major anticus, lie upon the forepart of the breast. LXVI. The serratus major anticus lies upon the side of the chest arising from the ribs ; and as the ribs have interstices betwixt them, every muscle arising from the ribs arises by distinct portions from each rib. All such distinct and pointed slips are named digitations, tongues, or serrae, from their re- sembling the teeth of a saw ; and every muscle arising from the ribs must be a serrated muscle. The serratus major anticus is that great and broad muscle, the chief part of which lies under the scapula ; and nothing of which is seen but the fleshy tongues, by which it arises from the sides of the ribs. It is all fleshy, and is of a considerable breadth and strength: it arises from all the true ribs, except the first, and from three of the fals,e ribs : its indigitations, of course, spread all over the side of the thorax like a fan : its upper indigitations lie under the pectoralis major, and its lower indigitations are mixed with the beginning of the abdominal muscles: its middle in- digitations are seen spreading upon the sides of the thorax : it lies thick and fleshy under the scapula, and is a part of that cushion on which the scapula glides : its fibres converge to- wards a narrower insertion ; and the muscle ends thick and fleshy in the whole length of that line which we call the basis of the scapula, and is, as it were, folded round it: so that this muscle, which comes from before, is implanted along with the rhomboides, which comes from behind. Perhaps, in difficult breathing, the shoulder blade being rais- ed and fixed by its own muscles, the serratus major may assist in heaving up the ribs : but its chief operation is upon the sca- pula ; for when the whole acts, it pulls the scapula downwards and forwards : when only the lower portions act, it pulls the lower angle of the scapula forwards, by which the scapula rolls, and the tip of the shoulder is raised ; when the upper part acts in conjunction with the little pectoral muscle, the tip of the shoulder is fixed and pulled downwards towards the chest, and the lower corner of the scapula rolls backwards. LXVII. The pectoralis minor lies under the pectoralis major, close upon the ribs; and as it arises from the third, fourth, and fifth ribs, it also is a serrated muscle, and was nam- ed serratus minor anticus : its three digitations are very thick and fleshy j they soon converge so as to form a small, but thick and fleshy muscle, which, terminating in a point, is inserted inio the very apex of the coracoid process : by pulling the cora- coid process forwards and downwards, it will roll the scapula. LXVIII. The subclavian muscle is another concealed muscles of THE ARM, &C 147 muscle of the scapula; for the clavicle is just the hinge upon which the scapula moves, and the subclavian muscle arises by a flat tendon from the cartilage of the first rib : it becomes flat and fleshy, and lies, along betwixt the clavicle and the first rib; it arises at a single point of the rib, flat and tendinous; but it is inserted into a great length of the clavicle, beginning about one inch from the sternum, and being inserted all along the clavicle, quite out to where it is joined to the acromion process. Its chief use (since the rib is immoveable) must surely be to pull the clavicle, and consequently the shoulder, downwards, and so to fix them. Many have affected to find other muscles of respiration than those which directly belong to the ribs. Among these are reckoned the serratus major, the pectoralis minor, &c.; but there is much reason to doubt whether aay muscles can have much effect which do not belong properly to the ribs : and it is manifest, that the subclavian can have none, since the first rib is quite rigid, has so little length of cartilage that it cannot bend nor move. The scapula is thus moved in every possible direction ; up- wards, by the levator and the trapezius ; backwards, by the rhomboides, assisted by other orders of the trapezius ; down- wards and backwards, by the lowest order of fibres in the tra- pezius ; downwards and forwards, by the serratus major anti- cus ; directly downwards, by the serratus, balanced by the tra- pezius, and assisted by the subclavius: and directiy forwards, by the pectoralis minor. MUSCLES OF THE ARM. VIZ. THOSE MOVING THE OS HUMERI, OR ARM BONE. LXIX. The pectoralis major is a large thick and fleshy muscle which covers all the breast. It arises from two-thirds of the clavicle next the sternum ; from all the edges of the sternum ; the cartilaginous endings of the fifth and sixth ribs. Where it arises from the sternum, it is tendinous, and the fibres from the opposite muscles cross and mix, so as to make a sort of fascia covering the bone. It is fleshy where it arises from the ribs, and there it mixes with the external abdominal mus- cle. The fibres approach each other till they form a flat ten- don about an inch in breadth ; and as the fibres approach each other, they cross in such a way, that the lower edge of the muscle forms the upper edge of the tendon, which is still flat, but twis- ter! : its implantation is into the edge, if I may call it so, of the 14a muscles of the arm, Sec. groove or rut which is in the shoulder bone for receiving the biceps tendon. That part which arises from the clavicle is a litde separated from that which arises from the sternum; a fatty line makes the distinction ; and they are sometimes des- cribed as two parts : it is those two bundles chiefly which cross each other to make the plaited appearance. The pectoralis, among others, has been made a muscle of respiration.* LXX. The latissimus dorsi is the broadest, not only of the back, but perhaps of the whole body. It is a beautiful mus- cle, covering all the lower part of the back and loins,'and reach- ing to the arm, to be the antagonist to the pectoral muscle. It arises by a broad, flat, and^glistehing tendon, which covers all the loins, and which is in some degree the root of other mus- cles, especially of the longissimus dorsi. This broad silvery tendon, begins exactly in the middle of the back ; it arises from the lower vertebrae of the loins, from the spines and knobs of the back of the sacrum, and from the back part of the circle of the os ilium : this last is the only part that is fleshy. The flat tendon gradually passes into a flat and regular muscle, which wraps round the side of the body ; and as it lies over the corn- er of the scapula, it receives a small fleshy bundle from it; and as it passes over the lower ribs, it has some tendinous slips sent into it, by which it is attached to the ribs. Its fibres converge: for the lower ones ascend ; the upper ones go directly across. And these different orders, not only meet to form its flat tendon, but they cross each other, like those of the pectoral muscle. Here also the tendon is twisted, and the upper edge of the muscle forms the lower edge of the flat tendon ; which passing into the axilla, turns under the arm-bone, and is implanted into it, on the inner edge of the bicipital groove. So the tendons of the pectoralis and latissimus meet each other ; they in fact join face to face, as if the one tendon ended directly in the other; and both united make a sort of lining for the groove, or a tendinous sheath for the long tendon of the biceps to run in. These two muscles form the axilla or arm-pit; and although each has its peculiar offices, their chief operation is when they coincide in one action ; and that action is exceedingly power- ful, both by the great strength of either muscle, and' by their • Haller tells us, that when at any time, he had rheumatism in this muscle, his breathing was checked; and when he had difficult breathing, he found great relief by fixing the hands, raising the shoulders, and acting with the pectoral muscles. It seems confirmed by these facts, that asthmatics take this posture ; women in la- bour fix their arms, by resting upon the arms of their chair; those who play OB wind instruments raise the shoulders in straining, &c. MUSCLES OP THE ARM, &C. 149 being implanted into the arm bone four inches below the head. The pectoralis major is for pulling the arm forwards, as in lay- ing the arms across the breast, or in carrying loads in the arms: and it forms the border of the axilla before. The latissimus dorsi has a wider range : when the arm is raised, it brings it downwards, as in striking with a hammer ; or downwards and backwards, as in striking with the elbow ; or in rolling the arm inwards and backwards, as in turning the palm of the hand be- hind the back; whence it has the obscene name of musculus scalptor ani, or tersor ani ; and it forms the back edge of the axilla. The edges of these two muscles receive the pressure of crutches, and defend the vessels and nerves : when both muscles act, the arm is pressed directly downwards, as in rising from our seat, or in holding a bundle under the arm ; or when the arm is fixed, these muscles raise the body, as in the example just mentioned of rising from our seat, or in walk- ing with a short stick, or in raising ourselves by our hands over a high beam. LXXI. The deltoides is the first of those muscles which arise from the scapula to be inserted into the shoulder-bone. It is named deltoid muscle, from its resembling the letter a of the Greeks ; it is thick and fleshy, and covers the top of the shoulder, filling up the space betwixt the acromion process and the shoulder-bone. It arises from all that part of the clavicle which is not occupied by the pectoralis muscle, and is separat- ed from it only by a fatty line : it arises again in another bun- dle, from the point of the acromion process ; and this middle bundle is also insulated by a fatty line on either side of it: the third bundle arises from the spine of the scapula, behind the acromion process. And thus the muscle has three converging heads, viz. a head from the outer end of the clavicle ; a head from the acromion or tip of the shoulder; ahead from the ridge of the spine ; each divided from the other by a fatty line.* These heads or bundles of fibres, meeting about one-third down the humerus, form a short flat, and strong tendon, which grasps or almost surrounds the shoulder-bone. These three distinct heads must be observed in speaking of the use of the muscle ; for though the chief use of the muscle be to raise the arm, this is not the use of it in all circumstances. For the outer and inner heads, lying by the side of the shoulder- bone, and below the joint, do, when the arm is lying flat by the side, assist the pectoral and latissimus dorsi muscles in draw- * Albinus has distinguished it into seven fasciculi or bundles; a very superflu- ous accuracy. 150 muscles of the arm, &c. ing it close to the side ; but when the middle bundle raises the arm, in proportion as it raises the arm it loses of its power; and in proportion as it loses of its power, the side portions, having come into a new direction, begin to help : nay, when the arm is raised to a certain point, more power still is required, and the clavicular part of the pectoral muscle also comes to assist. It is in this succession that the several bundles of fibres act; for if they began all at once to act, the arm should rather be bound down by the lateral portions than raised by the middle one. LXXII. Coraco brachialis.—The coraco brachialis, so named from its origin and insertion, is a long and rather slen- der muscle. It arises from the coracoid process of the scapula, along with the short head of the biceps muscle ; and it is closely connected with this head almost in its whole length : it is small at its be- ginning ; it grows gradually thicker as it descends; it is all fleshy, and is inserted by a very short tendon into the os hu- meri, nearly about its middle, betwixt the brachialis and the third head of the triceps. It is perforated by the musculo- cutaneous nerve. This was observed by Casserius, an Italian anatomist; and the muscle is often named, musculus perfor- atus casserii. Its action is very simple, to raise the arm obliquely forwards and upwards, and consequently to give a degree of rotation. It will also have a chief effect in pulling the arm towards the side. LXXIII. The supra spinatus, is so named from its occu- pying the hollow of the scapula above the spine. It arises from the back of the scapula, from the spine, and from the edge or costa ; it is exceedingly thick and fleshy, fill- ing up all the hollow ; and it is firmly inclosed in this triangu- lar hollow by a strong tendinous expansion, which passes from the edge of the scapula to the ridge of the spine. It is conse- quently a muscle of a triangular figure, thick and strong ; it passes under the acromion, and degenerates into a tendon there; and going under the acromion, as under an arch, and over the ball of the humerus, it adheres to the capsule of the shoulder-joint, and is at last implanted by a broad strong ten- don into the great tuberosity on the head of the bone. It is evidently designed for raising the humerus directly up- wards ; and by its attachment to the capsule, the capsule is drawn up when the arm is raised ; so that, though lax, it can- not be catched in the joint. It performs exactly the same mo- tion with the middle part of the deltoides, lies in the same direction with it, and assists it. MUSCLES OP THE ARM, &C 151 LXXIV. Infra spinatus, is like the former, in all respects, of the same use, and assists it. • This also is of a triangular shape, and is fully one half larger than the supra spinatus; and as the supra spinatus arises from all the triangular cavity above the spine, this arises from all the triangular cavity below it. It arises fleshy from all the back of the scapula below the spine itself, and from all the base of the scapula below the be- ginning of the spine, and also from the lower margin of the sca- pula. It is very thick and strong, filling up the triangular ca- vity entirely; and it is closed in like the former by a strong tendinous expansion ; it begins to grow tendinous about its middle, but it continues also fleshy till it passes over the socket of the shoulder-joint. It also is connected with the capsular ligament; is inserted into the same tuberosity with the former; and has exactly the same uses, viz. preventing the capsule from being catched in the joint, and raising the arm upwards, and inclining it a little outwards by a slight degree of rotation.— And I do believe that one great use of these two muscles is, when the arm is much extended backwards, to prevent the head of the humerus from starting out of its superficial socket. LXXV. The teres minor is a third muscle which co-ope- rates with these. This and another are named teres from their appearance, not from their shape ; for they seem round when superficially dissected, because then their edges only are seen; but when fully dissected from the other muscles, they are quite flat. The teres minor is a long, small fleshy muscle ; it arises from the angle, and all the lower edge of the scapula : it is like the infra spinatus ; it becomes early tendinous, but the tendon is accompanied with fleshy fibres from below ; its flat tendon, in passing over the joint, is attached to the capsule, and is finally inserted into the great tuberosity of the shoulder-bone, so that it must have exactly the same uses as the two former muscles. It is separated from the infra spinatus by that tendinous expan- sion with which the latter is covered ; it looks like a part of the same muscle in its origin, where it lies upon the scapula ; but is very distinct in its tendon. The supra spinatus, infra spinatus, and teres minor, raise the arm. LXXVI. The teres major, is in shape like the former, lies lower upon the edge of the scapula than the teres minor, and is thicker and longer than it. It arises chiefly from the angle of the scapula ; partly from the lower edge of the scapula at its back part; it is connected with the teres minor and infra spinatus. It is a large thick and flat muscle, and forms a flat strong tendon, which passes under the long head of the triceps. It passes under the os hu- 152 MUSCLES OF THE ARM, &C meri; turns round it, and is inserted into the ridge, on the in. ner side of the groove, and gives some tendinous fibres to line the groove. In short, it accompanies the tendon of the latissi- mus dorsi, is inserted along with it, and may be considered as the congener of the latissimus dorsi; and the two tendons are inclosed in one common capsule or sheath of cellular substance. Its use, then, is evidently to draw the humerus downwards and backwards, and to perform the same rotation of the arms which the latissimus dorsi does. LXXVII. The subscapulars lines all the concavity of the scapula like a cushion. It is like the surface of the scapula on which it lies, of a triangular shape ; and from the conver- gence of all the fibres, it is completely radiated or fan-like ; it is-very fleshy, thick, and strong. The radii are each minutely described by Albinus ; but Sabbattier says, with good sense, that he cannot distinguish them so as to describe them accu- rately ; and he might have added, that there was not the shadow of a motive for wasting time in so trivial an employment as counting the bundles. It arises from the two edges, the base, and all the .internal surface of the scapula. And indeed it is to favour this origin that the inner surface of the scapula is full of little risings and hollows, to every one of which the muscle adheres closely. Just under the coracoid process is the only part from whence it does not arise. That little space is filled up with cellular substance. Its alternately tendinous and fleshy fibres are so rooted in the scapula, and so attached to its risings and depressions, that it is difficultly cleaned away from the bone. The tendon and upper edge of the muscle is almost continu- ous with the supra spinatus : but from the manner of its inser- tion, its effect is very opposite from that of the supra spinatus; for it goes round the os humeri to its insertion, and it is fixed to the lesser tuberosity; therefore it both pulls the arm back- wards and downwards, and performs the rotation like the teres major and latissimus dorsi. It is also like all the other ten- dons, attached to the capsule, so as to prevent its being catch- ed ; and it is particularly useful by strengthening the shoulder- joint. OF THE MOTIONS OF THE HUMERUS. Having thus described all the muscles which move this bone, I shall review the order in which they are arranged, and mark their places and effects. MUSCLES OP THE ARM, &'C 153 To distinguish clearly the function of each muscle, we have but to mark the point to which it is attached. 1. Those implanted above the head of the bone must raise the arm. Now the supra spinatus, infra spinatus, and teres minor, are implanted into the great tubercle, and raise the arm; and the deltoides is implanted in the same direction, and still lower, so that it performs the same action with a still greater degree of power. 2. There is implanted into the opposite, or lower part of the head, the subscapularis, which, of course, draws the arm directly downwards and backwards. 3. There is implanted into the outer edge of the bicipital groove the pectoralis major, and also the coraco-brachialis, which comes in the same direction; and these two pull the arm inwards towards the side, or rather upwards. 4. There are inserted into the inside, or lower side of the groove, the latissimus dorsi and teres major ; both of which pull the arm direcdy backwards. As they bend under the arm, to reach their insertion, they also roll the palm inwards and backwards. And it is easy to observe in what succession those muscles must act, to describe the circular and rotatory motions of the arm. Joints are more strengthened by the origin and insertion of muscles around them, than by elastic ligaments : for these yield or tear ; whereas the muscles, having a living power, re-act against any separating force ; they contract, or, in other words, they are strong in proportion to the violence that the joint suffers. Thus, in the shoulder, the capsule is so lax, that there is a mechanical contrivance to prevent its being checked in the joint; and it is moreover so weak, that inde- pendent of its yielding easily, it is also very easily torn ; but these muscles surround the joint so fairly, that their strength and their tendinous insertions into the head of the bone are more than a compensation for the looseness of its capsular liga- ment. Were not the muscles thus closely attached, the shoulders would be very often displaced, the glenoid cavity is so superficial, and the bursa so lax: and surely it is for some such purpose that the muscles are planted so closely round the head of the bone ; for when they are implanted at a distance from the centre, as one muscle, the deltoid, is, or as the biceps and triceps of the arm, or as the hamstrings, or tendo Achillis are, the power is much increased. Here, in the humerus, power is sacrificed to the firmness of the joint, and they are all implanted closely round the head of the bone. The joint is in a manner formed by these muscles ; for the supra spinatus, infra spinatus, teres major and minor, and the Vol. I. U 154 MUSCLES OF THE ARM, &C subscapularis, surround the joint very closely; cover the joint with their flat tendons ; and so thicken the capsule, and in- crease its strength. MUSCLES OF THE FORE-ARM. The muscles of the fore-arm are only four ; the biceps and brachialis for bending, and the triceps and anconeus for extending. LXXVIII. Biceps brachii flexor is universally named Biceps, from its having two very distinct heads. It is an ex- ceedingly thick and strong muscle ; for when it contracts, we feel it almost like a hard firm ball upon the forepart of the arm ; and at the upper and most conspicuous part of this ball is the union of the two heads. The larger and thicker head arises from the coracoid pro- cess, by a tendon which extends three inches along the forepart of the muscle, in the form of an aponeurosis ; but at the back part the tendon is short, and the muscle is fleshy, and is attached there to the fleshy belly of the coraco-brachialis. The second, or long head, arises from the edge of the glenoid cavity, at its upper part ; it is exceedingly small and tendinous, and this long tendon runs down in its proper cavity, till, about one-third down the arm, the two heads meet. And though below that it is but one fleshy belly, yet there, as in other muscles, the common division betwixt its two origins may be still observed. It is earlier tendinous at the forepart and outer side ; the tendon there sends off that aponeurotic expansion which covers all the fore-arm below, and encloses its muscles as in a sheath. The tendon, at first flat and large, becomes gradually smaller and rounder; it turns a little in its descent, so as to lay one flat edge to the radius, and another to the ulna ; and it is at last implanted into that round tubercle which is on the forepart of the radius, a little below its neck. ' The great use of the biceps is to bend the fore-arm ; which it does with great strength. But as it is inserted into the tubercle of the radius, when the arm and hand are turned downwards, the biceps, by acting, will pull them upwards, i. e. it will assist the supinators. Since both its heads are from the scapula, it will also occasionally move the humerus, as well as the fore-arm. LXXIX. The brachialis internus lies immediately un- der the biceps, and is a very strong fleshy muscle for i ssisting the biceps in bending the arm. It is called brachialis from MUSCLES OF THE ARM, &C. 155 its origin in the fore-arm; and internus from its being within the biceps, or rather from its being on the inner side of the arm. It arises from two-thirds of the os humeri at its forepart, by a sort of forked head ; for it comes down from each side of the deltoid. It continues its attachment all the way down the forepart of the humerus to within an inch of the joint. It is very thick, fleshy, and strong ; it is tendinous for about two inches in its forepart; and is inserted by a flat strong tendon into the coronoid process of the ulna. Other uses are ascribed to it, as the lifting up the capsule to prevent its being pinched; but the chief use of it is to bend the fore-arm. In a strong man, it is exceedingly thick, and its edge projects from under the edge of the biceps, and is seen in the lateral view. LXXX. Triceps extensor.—Upon the back part of the arm three muscles are described: die extensor longus, the extensor brevis, and the brachialis externus ; but it is, in fact, one three-headed muscle. The longest head of this muscle is in the middle. It arises by a flat tendon of one inch in thickness, from the edge of the scapula under the neck, and a little way from the origin of the long head of the biceps ; and it is under this head that the tendon of the teres major passes to its insertion. The second head is on the outside of the arm, next in length to this. It arises from the arm-bone under the great tuber, and just below the insertion of the teres minor. These two meet about the middle of the humerus. The third, or internal head, is the shortest of all. It begins at the inner side of the humerus, just under the insertion of the teres major; and it arises from the inner part ot the humerus, all the way down, and joins just where the second head joins (i. e. about the middle.) All these heads still continue ad- hering to the humerus (as the brachialis does on the fore side,) quite down to within an inch of the joint; and then a strong thick tendon is formed, by which it is implanted strongly in the projecting heel of the ulna, named olecranon; by which pro- jection it has great power, and the power is increased by an increased length in dogs, and other animals which run or bound. The whole forms a very thick and powerful muscle, which covers and embraces all the back part of the arm ; and its use is too simple to admit of any farther explanation, than just to say that it extends the hinge-joint of the elbow with great pow- er j and that by its long head it may assist also to bend the shoulder outwards and backwards. Besides bones, there is also another source of attachment for 156 MUSCLES OF THE ARM, &C. muscles, that is, the tendinous expansions: for the expansions,, which go on the surface like sheaths, also dive betwixt the muscles, and form septa or partitions, from which their fibres arise. One tendinous expansion begins from the clavicle and acro- mion process, or rather comes down from the neck : it is then strengthened by the tendon of the deltoid muscle ; it descends, covering all the arm ; and before it goes down over the fore- arm, it is again re-inforced chiefly by the biceps, but also by the tendon of the extensor triceps. One remarkable process or partition of this general fascia is sent in from the sheath to be fixed to the outside of the humerus, all the way down to the ridge of the outer condyle. Another partition goes down, in like manner, to the inner condyle, along the ridge which leads to it; then the fascia, taking a firm hold on the condyles, is greatly strengthened about the elbow, and goes over the fore- arm, inclosing its muscles in a very firm and close sheath ; and it sends partitions down among the several layers of muscles in the fore-arm, which gives each of them a firm hold. LXXXI. The anconeus is a small triangular muscle, plac- ed on the back part of the elbow. It arises from the ridge and from the external condyle of the humerus, by a thick, strong, and short tendon. From this it becomes fleshy; and after running about three inches obliquely backwards, it is inserted by its oblique fleshy fibres into the back part or ridge of the ulna. It is manifestly designed for the extension of the fore-arm, and has only that one simple action. MUSCLES OF THE RADIUS, CARPUS, AND FINGERS. The whole fore-arm is covered with a mass of muscles of great strength, and so numerous and intricate, with a catalogue of names so difficult, and so distracting, that they should be arranged and classed with much care, explaining to the student the reason and value of their names, and the place and effect of each class. The fore-arm is covered with a fascia or strong tendinous web, which, like that which covers the temporal muscle, gives both origin and strength to the muscles which lie under it; which divides the several layers one from another ; and helps them in their strong actions, with that kind of support which workmen feel in binding their arms with thongs. This fascia is said to proceed from the small tendon of the biceps muscle, MUSCLES OF THE ARM, &C. 157 though that were but a slender origin for so great a web of ten- don, which not only covers the surface of the muscles but ent- ers among their layers. This fascia really begins in the shoul- der, and has an addition and an increase of strength from every point of bone ; it is assisted by each tendon, because the ten- dons and fascia are of one nature over all the body, and its connection with the tendon of the biceps is quite of another kind from that which has been Supposed. I would not allow that the biceps tendon expands into the fascia, but rather that the web receives the biceps tendon, which is implanted into it; and for this wise purpose, that when the fore-arm is to strike, or the hand to grasp, the biceps first moves, and by making the fascia tense, prepares the fore-arm for those violent actions which are to ensue. Thus, it may be defined a web of thin but strong tendon, which covers all the muscles of the fore- arm ; makes the surface before dissection firm and smooth ; sends down partitions, which are fixed into the ridges of the radius and ulna, enabling those bones to give a broader origin to the muscles, establishing a strong connection among the several layers, and making the dissection always difficult, and never fair nor clean. The motions to be performed by the muscles which lie upon the fore-arm are these three ; to roll the hand; to bend the wrist; to bend the fingers. 1. The turning of the hand, which is performed by rolling the radius on the ulna, is named pronation and supination.— When we turn the palm down, it is said to be prone ; when we turn the palm upwards, it is supine. This is pronation and supination. The muscles which perform these motions are the pronators and the supinators ; and the motion itself is best exemplified in the turning of a key in a lock, or in the guards of fencing, which are formed by a continual play of the radius upon the ulna, carrying the wrist round in circles. 2. The wrist is called the carpus, and therefore those mus- cles which serve for bending or extending the wrist are the flexors and extensors of the carpus. 3. The bending and extending of the fingers cannot be mis- taken ; and therefore the flexors and extensors of the fingers need not be explained. These muscles are denominated from their uses chiefly ; but if two muscles perform one motion, they may be distinguished by some accident of their situation or form. And thus, if there be two benders of the fingers, one above the other, they are named flexor sublimis, and flexor profundus, i. e. the deep and the superficial flexors. If there be two flexors of the carpus, one is named flexor radialts carpi, by its running 158 MUSCLES OF THE ARM, &C. along the radius; the other flexor ulnaris carpi, front passing along in the course of the ulna. And if there be two pronators, one may be distinguished as the pronator teres, from its round shape, the other as the pronator quadra- tus, from its square form. And this, I trust, will serve as a key to what is found to be a source of inextricable confusion. It will be easy to make the origins and insertions of these muscles still more simple thatk their names ; for all the mus- cles arise from two points, and have but two uses. This as- sertion shall be afterwards qualified, with a few exceptions; but at present it shall stand for the rule of our demonstration; for all the muscles arise from two points, the external and the internal condyle. The internal condyle is the longer one, and gives most pow- er » more power is required for bending, grasping, and turning the hand; therefore all the muscles which bend the hand, all the muscles which bend the fingers, and the pronator, or that which turns the palm downwards, arise from the internal con- dyle. The external condyle is shorter ; it gives less power ; there is little resistance to the opening of the hand, and little power is required in extending the fingers ; and so all the muscles which extend the wrist or the fingers, or roll the hand outwards to turn it supine, arise from the external condyle. So that when we hear a pronator or a flexor named, we know that the origin must be the internal condyle, and the insertion is expressed by the name : thus a pronator radii is a turner of the radius, and goes to the radius ; a flexor carpi goes to the wrist; a flexor digitorum goes to the fingers ; and a flexor poll- icis goes to the thumb : all the flexors, and all the pronators, issue from that point as from a centre. And, again, when a supinator or an extensor is named, we know where to look for it; for they also go out from one common point, the external condyle ; and the supinator radii goes to the radius ; the ex- tensor carpi goes to the wrist; the extensor pollicis goes to the thumb ; and the extensor indicis to the fore-finger. FLEXORS. The muscles closing and bending the hand arise from the internal condyle. They are, The pronator teres radii, turning the radius. Palmaris longus, "j Flexor carpi radialis, I bending the wrist. __— —— ULNARISjJ MUSCLES OF THE ARM, &C. 159 Flexor digitorum sublimis, ------------profundus, i LONGUS POLLICIS, And, lastly, there is the pronator quadratus, which is the single muscle out of that scheme which I have proposed j lying flat upon the interosseous membrane near the wrist. LXXXII. The pronator teres radii is of the outermost layer ot muscles, is small and round; named pronator from its office of turning the radius, and teres from its shape, or rather to distinguish it from the pronator quadratus, which is a short square muscle which lies deep again, being laid flat upon the naked bones. The pronator teres arises chiefly from the internal tubercle of the humerus, at its lower and fore part: it has a second ori- gin from the coronoid process of the ulna. These form two portions, betwixt which passes the radial nerve. The muscle thus formed is conical; is gradually smaller from above down- wards ; is chiefly fleshy, but is also a little tendinous, both at its origin and at its insertion ; and stretches obliquely across the fore-arm, passing over the other muscles to be inserted in the outer ridge of the radius, about the middle of its length. Its use is to turn the hand downwards, by turning the radi- us ; and it will also, in strong actions, be brought to bend the fore-arm on the arm ; or the reverse, when the fore-arm is fixed, and we are to raise the trunk by holding with the hands. LXXXIII. The palmaris longus is a long thin muscle, which, although it seems to have another use in its expansion into the aponeurosis ; yet is truly, by its insertion into the annu- lar ligament of the wrist, a flexor of the wrist, and, in some de- gree, a pronator of the radius. It arises from the internal condyle of the os humeri, and is first of five muscles which have one common tendon, and which go out, like radii, from one common centre ; viz. the palmaris, the flexor radialis, the flexor ulnaris, the flexor digitorum sub- limis, the flexor digitorum profundus. The palmaris longus arises from the inner condyle of the os humeri, and also from the intermuscular tendon, which joins it with the flexor radialis and flexor digitorum sublimis, and from the internal surface of the common sheath. Its fleshy belly is but two inches and a half or three inches in length ; and its long slender tendon descends along the middle of the fore- arm to be inserted into the fore part of the annular ligament of the wrist, just under the root of the thumb. This tendon seems to give rise to the very strong thick aponeurosis of the palm, of the hand (under which all the muscles of the hand run, and which conceals the arch of blood vessels, and protects them,) } bending the fingers and thumb. 160 MUSCLES OF THE ARM, &C. thence the muscle has its name. But it is a very common mis- take to think, that because tendons are fixed to the sheaths, the sheaths are only productions of the tendons; whereas the • sheaths do truly arise from bones. The fascia, which die del- toides is thought to form, arises from the acromion and clavicle; and the fascia, which the biceps is thought to produce, arises from the condvles of the humerus ; and that great sheath of tendon which is made tense by the musculus fascialis of the thigh, does not arise from that muscle, but comes down from the spine of the ilium, strengthened by expansions from the oblique muscles of the abdomen. In the present instance, we have the clearest proof of fascia being derived from some other source than the tendons; for sometimes the palmaris muscle is wanting, when still the tendinous expansion is found, and some pretend to say that the expansion is wanting when the muscle is found. The aponeurosis, which covers the palm, is like the palm itself, of a triangular figure ; it begins from the small tendon of the palmaris longus, and gradually expands, covering the palm down to the small ends of the metacarpal bones. Its fibres expand in form of rays ; and towards the end there are cross bands which hold them together and make them stronger ; but it does not cover the two outer metacarpal bones (the metacarpal of the fore-finger or of the little finger,) or it only covers them with a very thin expansion. Now this palmar expansion also sends down perpendicular divisions, which take hold on the edges of the metacarpal bones : and thus there being a perpendicular division to each edge of each metacarpal bone, there are eight in all, which form canals for the tendons of the fingers, and for the lurnhri* cales muscles. LXXXIV. The palmaris brevis is a thin flat cutaneous muscle, which arises properly from the edge of the palmar aponeurosis, near to die ligament of the wrist; whence it stretches across the hand in thin fasciculi of fibres, which are at last inserted into the metacarpal bone, on which the little finger stands, and into the skin and fat on the edge of the palm. This is the palmaris cutaneus of some authors, for which we can find no use except it were that of drawing in the skin of the hand, and perhaps making the palmar expansion tense. LXXXV. The flexor carpi radialis is a long thin muscle arising from the inner condyle, stretching along the middle of the fore-arm somewhat in the course of the radius, and is one of the five muscles which rise by one common ten- don, and which are, for some length, tied together. It arises tendinous from the inner condyle ; the tendon very .MUSCLES OF THE ARM, &C. 161 short and thick. This tendon, at its origin, is split into many (seven) heads, which are interlaced with the heads of the sublimis, profundus, palmaris, &c.; consequendy this mus- cle not only arises from the internal condyle, but also from the intermuscular partitions (as from that betwixt it and the sub- limis) : it forms a long tendon, which, becoming at last very small and round, runs under the annular ligament: it runs in a gutter peculiar to itself; but in this canal it is moveable, not fixed: it then expands a very little, and is inserted into the metacarpal bone of the fore-finger, also touching that which supports the thumb. Its use is chiefly to bend the wrist upon the radius. But when we consider its oblique direction, it will also be very evident that it must have some effect in pronation ; and this, like many of the muscles of the fore-arm, although designed for a different purpose, will also have some effect in bending the fore-arm at the elbow-joint. LXXXVI. The flexor carpi ulnaris is along muscle, much like the former ; but as its course is along the radius or upper edge of the fore-arm, this runs along the ulna or lower edge. It comes off tendinous from the inner condyle of the os humeri, by the common tendon of all the muscles : it has also, like the pronator teres, a second head (viz. from the olecranon process of the ulna), which arises fleshy; and as the radial nerve passes betwixt the heads of the pronator teres, the ulnar nerve perforates this muscle betwixt its heads. The flexor ulnaris passes all along the flat side of the ulna, betwixt the edge of the sublimis and the ridge of the bone : and here it has a third origin of' oblique fibres, which come from the edge of the ulna two-thirds of its length. Its tendon begins early on its upper part, by which it has somewhat the form of a pen- niform muscle. It has still a fourth origin from the inter- muscular partition, which stands betwixt it and the sublimis flexor ; and is also attached to the internal surface of the com- mon fascia of the arm. Its long tendon is at last inserted into the os pisiforme at its forepart, where it sends off" a thin ten- dinous expansion to cover and strengthen the annular liga- ment ; and also a thin expansion towards the side of the little finger to cover its muscles. This is to balance the flexor radialis : acting together, they bend the wrist with great strength ; and when this acts alone, it pulls the edge of the hand sidewise. LXXXVII. The flexor digitorum sublimis, is named sublimis from beingthe more superficial of the two muscles; pf.rforatus, from its tendon being perforated by the tendow Vol. I. X 162 MUSCLES OB THE ARM, &C. of that which lies immediately below. It lies betwixt the pal- maris longus and flexor ulnaris. It is a large fleshy muscle j and not only its tendons, but its belly also, is divided into four fasciculi, corresponding with the fingers which it is to serve. It arises from the internal condyle, along with the other four muscles; from the ligament of the elbow joint; from the coronoid process of the ulna ; and from the upper part of the radius, at the sharp ridge. By these origins it becomes very fleshy and thick; and a little above the middle of the fore-arm divides into four fleshy portions, each of which end% « in a slender tendon. The tendons begin at the middle of the fore-arm or near the division ; but they continue to be joined to each other by fleshy fibres some way down : and indeed the fleshy fibres cease only when it is about to pass under the an- nular ligament of the wrist. At this place a cellular stringy tissue connects the tendons with each other, and with the ten- dons of the profundus ; but after they have passed under the ligament, they expand towards the fingers which they are to serve. They each begin to be extended and flattened, and to become thinner; they begin to appear cleft; they pass by the edge of the metacarpal bones, and escape from under the pal- mar aponeurosis: and where it ends, viz. at the root of the fingers, a tendinous sheath or bursa begins, in which these ten- dons continue to be inclosed. The tendons are fairly split just opposite to the top of the first phalanx : and it is at this point that the tendons of the deeper muscle pass through this splitting. The flattened ten- don parts into two, and its opposite edges diverge ; the back edges meet behind the tendons of the profundus, and form a kind of sheath for them to pass in ; and then they proceed forward along the second phalanx, into the forepart of which they are implanted. This muscle is exceedingly strong. Its chief office is to bend the second joint of the fingers upon the first, and the first upon the metacarpal bone. And in proportion to the number of joints that a muscle passes over, its offices must be more numerous ; for this one not only moves the fingers on the metacarpus, but the hand upon the wrist, and even the fore- arm upon the arm. LXXXVIII. The flexor digitorum profundus vel per- forans, has the same origin, insertion, and use, insomuch that the description of the last is applicable to this muscle in almost every point. This is of a lower stratum of muscles ; it lies deeper, and under the former, whence its name : and by this deeper situation it is excluded from any hold upon the tubercle of the humerus. MUSCLES OF THE ARM, &C 163 It arises from the ulna, along its internal surface ; from the whole surface of the interosseus ligament j and also in some degree from the intermuscular membrane, which separates this from the sublimis. This muscle is small, we may say compressed, above ; but it grows pretty strong and fleshy near the middle of die arm ; it divides above the middle of the arm into four portions, cor- responding with the four fingers; and it is about the middle of the arm that the tendons begin, and continue to receive . muscular fibres from behind, all down to the ligament of the wrist. At the wrist these tendons are tied to each other, and to the tendons of the sublimis, by loose tendinous and cellular fibres. They diverge from each other, after passing under the annular ligament,; and going along in the hollow of the bones, under the tendons of the sublimis, they first pass through the bridges formed by the palmar aponeurosis, then enter the sheaths of the fingers, and finally pass through the perforations of the sublimis, a little below the second joint of the fingers. At this place the perforating tendons are smaller and rounder for their easy passage ; and after passing they again expand and become flat. They also above this appear themselves split in the middle, without any evident purpose ; they pass the se- cond phalanx, and are fixed into the root of the third. And every thing that is said of the use of the sublimis may be ap<- plied to this, only that its tendons go to the furthest joint. LXXXIX. Lumbricales.—I shall here describe, as a na- tural appendage of the profundus, the lumbricales muscles, which are four small and round muscles, resembling the earth- worm in form and size; whence they have their name. They arise in the palm of the hand, from the tendons of the profun- dus, and are therefore under the sublimis, and under the palmar aponeurosis. They are small muscles, with long and very de- licate tendons. Their fleshy bellies are about the length of the metacarpal bones, and their small tendons stretch over two joints, to reach the middle of the second phalanx. The first lumbricalis is larger than the second, and the two first larger than the two last. The first arises from the side of the tendon of the fore-fin- gers, which is next to the radius ; the others arise in the forks of the tendons ; and though they rise more from that tendon which is next the ulna, yet they have attachments to both. Their tendons begin below the first joint of each finger ; they run very slender along the first phalanx, and they gradually wind around the bone ; so that though the muscles are in the palm of the hand, the tendons are implanted in the back parts of the fingers ; and their final connection is not with the bend- 164 MUSCLES OP THE ARM, &C. ing tendons of the sublimis and profundus, but with tendons of the extensor digitorum, and with the tendons of the external interossei muscles, and with which they are united by tendi- nous threads. Hence their use is very evident: they bend the first joint, and extend the second ,* they perform alternately either office: when the extensors act, they assist them by extending the se- cond phalanx or joint: when the flexors act, and keep the first and second joint bended, the extending effect of these smaller muscles is prevented, and all their contraction must be directed so as to affect the first joint only, which they then bend. They are chiefly useful in performing the quick short mo- tions,and so they are named by Cowper the musculi fidicinales, as chiefly used,in playing upon musical instruments. XC. The flexor longus pollicis is placed by the side of the sublimis orperforatus,and lies under the extensor, or rather extensores carpi. It runs along the inner side of the radius, whence chiefly it arises. Its origin is from all the internal face of the radius down- wards ; from the place where the biceps is inserted, and from the interosseus ligament, all the length down to the origin of the pronator quadratus, nor does it even stop here; for the tendon continues to receive fleshy slips all the way down to the entry, under the ligament of the wrist. It has often also ano- ther head which arises from the condyle of the humerus and the forepart of the ulna; which head is tendinous, and joins near the top of that origin which come from the radius. It becomes tendinous very high, i. e. above the middle of the arm; and its small tendon passes under the annular ligament, glides in the hollow of the os metacarpi pollicis, and separates the short flexor into two heads; passes betwixt the two sesa- moid bones in the first joint of the thumb, and running in the tendinous sheath, it reaches at last the end of the farthest bone, to be inserted into the very point of it. There is sometimes sent off* from the lower part of the mus- cle a small fleshy slip, which joins its tendon to the indicator tendon of the sublimis. Its uses, we conjecture, are exactly as those of the other flexors, to bend the last phalanx on the first, the first on the metacarpal bones, and occasionally the wrist upon the radius and ulna. XCI. The pronator quadratus, so named from its shape and form, is one of the most simple in its action, since it serves but one direct purpose, viz. turning the radius upon the ulna. It lies flat upon the interosseous ligament, upon the fore part of the arm, about two inches above the wrist; it is nearly MUSCLES OF THE ARM, &C 165 square, and is about three inches in length and breadth. Its fibres go obliquely across, betwixt the radius and ulna. It ari- ses from the edge of the ulna, adheres to the interosseus liga- ment, and goes to be implanted into the edge of the radius.— It turns the radius upon the ulna ; and this muscle, and in some degree also the flexor pollicis, are the only muscles which do not come fairly under that arrangement by which I have endea- voured to explain the muscles of the fore-arm. extensors. The muscles which lie upon the outer side of the fore-arm, the supinators and the extensors of the fingers and wrist, all arise from one point, the external condyle of the humerus, and are all delivered in this list: The EXTENSOR CARPI RADIALIS LONGIOR,-} ,, , , The EXTENSOR CARPI RADIALIS BREVIOR, J- - en e I wrist. The EXTENSOR CARPI ULNARIS, J The supinator longus,—turns the palm upwards. The extensor communis digitorum,—extends all the fin- gers, and unfolds the hand. The EXTENSOR PRIMI internodii POLLICIS,'] | , The extensor secundi internodii pol- { ... ese" r*veral joints of "CIS' , „ j the thumb. The EXTENSOR TERTII INTERNODII POLLICIS,J The extensor primi digiti, vel indicator,—extends the fore-finger. The extensor minimi digiti, vel auricularis,—extends the little finger. All these muscles arise from one point, the external condyle. They all roll the radius outwards, or extend the wrist, or ex- tend the fingers. As the muscles which bend need more fibres and greater strength, they arise from the internal condyle, which is the larger ; they lie in a deep hollow, for the bones of the fore-arm bend to conceal them, and they form a very thick fleshy cushion ; but the extensors requiring less power, arise from the shorter process of the outer condyle, are on the con- vex side of the arm, and are thin, having few fibres : for though there is a large mass of flesh on the inner side of the arm, form- ing two big flexors, there is only a thin layer on the outer side of the arm, forming one flat and weak extensor. XCII. Supinator radii longus. This muscle forms the very edge of the fore-arm : it arises by many short tendinous fibres from the ridge of the humerus, above the external con- dyle, which origin is fully two inches in length above the con- 166 MUSCEES 07 THE ARM, &C. dyle. It also arises from the inter-muscular membrane ; and, as it stands on the very edge of the fore-arm, it runs betwixt the flexor and extensor radialis. It becomes thicker as it passes the elbow-joint, and there gives a very peculiar form to the arm : it then becomes smaller, and forms a flat tendon, which is quite naked of flesh from the middle of the radius, or a little below, down to the wrist. This tendon becomes gradually smaller till it reaches the wrist, where, expanding a little, it is inserted into the radius, just in the tuber of its lower head. Its use is perhaps chiefly as a supinator, but it is placed just upon the edge of the arm: it stands as a sort of intermedium betwixt the two sets of muscles ; it is fixed indeed rather upon the internal surface of the radius ; but yet when the supination is complete, when the hand is rolled very much outward, it will become a pronator. It is all at once supinator and pronator, and, for a most evi- dent reason, a flexor also of the fore-arm ; since its origin is at least two inches up the humerus, above the joint of the el- bow. XCIII. The extensor carpi radialis longior has the additional name of longior or primus, t8 distinguish it from the next. It is almost entirely covered with the last muscle, the supinator. It arises from the ridge of the humerus above the external condyle, and just under the origin of the supinator ; it descends all along the back of the radius, and after having become a thick fleshy belly, it degenerates a little lower than the middle of the radius into a thin flat tendon, which becomes slender and small as it descends ; and turning a little more towards the back of the radius, it then passes over the wrist, and goes along with the tendon of the extensor brevior, under the annular lig- ament, passing in a groove of the radius ; at last it is inserted into the root of the metacarpal bone of the fore-finger, in that edge next the thumb. It is chiefly an extensor of the wrist: in pronation, it pulls the, wrist directly backwards ; in supination, it moves the hand sidewise. It is also a pronator when the hand is turned back to the greatest degree ; and from its origin, high upon the shoulder-bone, it is also a flexor of the fore-arm. XCIV. Extensor carpi radialis brevior. This mus- cle is almost the same in description, name, and use, with the former. It arises from the external condyle ; and here a com- mon tendon for many muscles is formed, just as in the internal condyle ; for from this point arise the extensor brevis exten- sor digitorum, extensor minimi digiti, extensor carpi ulnaris. The extensor carpi radialis brevior arises from the outer con- MUSCLES OF THE ARM, &C 167 dyle of the humerus, by the common tendon ; it also arises from the aponeurosis, which lies betwixt the extensor digito- rum and this ; it grows a pretty large fleshy belly, and begins like the last to be tendinous below the middle of the radius; so that this muscle continues fleshy lower than the last one.— Its tendon is also much larger and thicker ; it runs under the annular ligament, in the same channel with the extensor lon- gior ; it expands a little before its insertion, which is into the fore part of the metacarpal bone of the middle finger, a little towards that edge, which is next to the radius: some little fibres pass from this tendon to die metacarpal bone of the fore-finger. All that was said concerning the extensor longus may be said of this ; for all the three last muscles lie so ambiguously on the edge of the arm, that though they are regularly supinators and extensors, they become pronators and flexors in certain po- sitions of the hand. XCV. Extensor carpi ulnaris.—By the name merely of this muscle we know its extent and course, its origin, inser- tion, and use. It is one of the muscles which belong to the common tendon, arising from the external tubercle of the os humeri: it lies along the ulnar edge of the arm; it arises also from the inter- muscular membrane, which separates this from the extensor digitorum and the extensor digiti minimi; and chiefly it is at- tached to the internal surface of the common sheath. It arises also from the face and edge of the ulna the whole way down; its tendon begins in the middle of its length, and is accom- panied all down to the wrist with feather-like fleshy fibres. It is fixed into the outside of the lower head of the metacar- pal bone of the little finger. Its use is to extend the carpus. And it may be now observ- ed, that wheu the two extensors of the wrist, the radialis and ulnaris, act, the hand is bent directly backwards ; that when the flexor radialis and extensor radialis act together, they bend the thumb towards the radius; and that when the flexor ulnaris and extensor ulnaris act, they bend the little-finger towards the ulna, as in cutting with the edge of the hand: thus a circle may be described by acting with those in succession. XCVI. Extensor digitorum communis.—This muscle corresponds with the sublimis and profundus, and antagonises them, and resembles them in shape as in use. It covers die middle of the fore-arm at its back, and lies betwixt the exten- sor radialis secundus and the extensor minimi digiti. Its origin is chiefly from the outer condyle, by a tendon com- mon to it, with the extensor carpi brevior, and also from the intermuscular membrane, which separates it on one side from 168 MUSCLES OF THE ARM, &C the extensor minimi digiti, and on the other from the extensor carpi brevis, and also from the back part of the common sheath. It grows very fleshy and thick as it descends, and about the middle of the fore-arm it divides itself into three slips of very equal size. But though the tendons begin so high, they con- tinue, like those of the flexors, to receive fleshy penniform fibres all down, almost to the annular ligament. These tendons are tied together by a loose web of fibres ; and being gathered together, they pass under the ligament in one common and ap- propriated channel. Having passed this ligament, they di- verge and grow flat and large ; and they all have the appear- ance of being split by a perpendicular line. They are quite different from the flexor tendons in this, that they are all tied to each other by cross bands ; for a little above the knuckles, or first joint of the fingers, all the tendons are joined on the back of the hand by slips from the little-finger to the ring, from the ring to the mid-finger^ and from that to the fore-finger. So that it seems to be one ligament running quite across the back of the hand. It would be foolish to describe them more mi- nutely ; for the cross bands change their places, and vary in every subject, and in some they are not found. After this the tendons pass over the heads of the metacarpal bones, along the first phalanx of the fingers ; and being there joined by the tendons of the interossei and lumbricales, they altogether form, a strong tendinous sheath, which surrounds the back of the fingers. Now, it is to be remembered, that this muscle serves only for the fore, middle, and ring fingers : that if it moves the lit- tle finger, it is only by a small slip of tendinous fibres, which it often gives off"at the general divergence, but sometimes not; sometimes it gives one slip, sometimes two, often none at all. And so the little finger has its proper extensor quite distinct from this. The use of this muscle is to extend all the fingers ; and when they are fixed, it will assist the extensors of the wrist, as in striking backwards with the knuckles. And since there is but one extensor muscle, the cross tendons are a provision against the bad consequences of an}- single tendon being cut across. XCVII. The extensor minimi digiti, named also auri- CULARis from its turning up the little finger, as in picking the ear, should really be described with the last muscle. If we see the origin, course, and use of this muscle exactly the same with the common extensor, why should we not reckon it as a slip of the common extensor, appropriated to the little finger? Its origin is from the outer condyle, along with the other tendons. It also adheres so closely both to the tendinous par- MUSCLES OP THE ARM, &C 169 titions, and to the internal surface of the common fascia, that it is not easily separated in dissection. It begins small, with a conical kind of head ; it gradually, increases in size; it is pretty thick near the wrist; it adheres all along to the common extensors of the fingers; it begins to be tendinous about an inch above the head of the ulna; it continues to receive fleshy fibres down to the annular ligament; and it passes under the annular ligament in a channel peculiar to itself, which is indeed the best reason for making this a distinct muscle. This channel has a very oblique direction ; and the tendon, like all the others, expands greatly in escaping from the liga- ment of the wrist. It is connected with the other tendons in the manner I have described. Close to the wrist, it is con- nected with the tendon of the ring-finger, by a slip which comes from it; and at the knuckle, and below it, it is again connected with the tendons both of the ring-finger and of all the others by the cross bands or expansions. Whatever has been said of the use of the last muscle is to be understood of this; as its extending its proper finger, assisting the others by its communicating band, and in its ex- tending the wrist when the fist is clenched. Its insertion is in- to the back of the second joint of the little-finger, along with the interossei and lumbricales. Its tendon has also a small slit; for the head of the proper extensor of the little-finger, and the heads of the common extensors of the others, are in- serted into the top of the second phalanx, just under the first joint. They send, off at the sides tendinous slips, which, pas- sing along the edges of the bones, do, in conjunction with the tendons of the interossei and lumbricales, form a split tendon, which meets by two curves at the foot of the last bone of the fingers to move the last joint. XCVIII. The extensor primus pollicis, is the shortest of the three extensors of the thumb. It is named by Albinus and others abductor longus ; but since every muscle that extends the thumb must pull it away from the hand, every one of them might be with equal propriety named abductors. The extensor primus lies just on the fore edge of the radius, crossing it obliquely. It arises about the middle of the fore-arm, from the edge of the ulna, which gives rise to the interosseous membrane itself, and also from the convex surface of the radius. The fleshy belly commonly divides itself into two or three, sometimes four fleshy slips, with distinct tendons ; which crossing the radius obliquely, slip under the external ligament of the carpus, and are implanted into the root of the first me- tacarpal bone, or rather of the first phalanx of die thumb, to- Vol. I. Y 170 MUSCLES OF THE ARM, &C. wards the radial edge ; so that its chief use is to extend the thumb, and to incline it a litde outwards towards the radius. It must also, like the extensors of the fingers, be an extensor of the wrist: and it evidently must, from its oblique direction, assist in supination. XCIX. The extensor secundus pollicis is longer than the first. It is named by Douglas the extensor secundi in- ternodii pollicis ; by Albinus the extensor minor pollicis. This muscle lies close by the former. It arises just below it, from the same edge of the radius, and from the same sur- face of the interosseous membrane ; it runs along with it in the same bending course ; and, in short, it resembles it so much, that Winslow has reckoned it as part of the same muscle. Its origin is from the edge of the ulna, the interosseous ligament, and the radius. Its small round tendon passes sometimes in a peculiar channel, sometimes with the extensor primus. It goes over the metacarpal bone of the thumb ; it ex- pands upon the bone of the first phalanx; and it is inserted just under the second joint. It extends the second bone of the thumb upon the first; it extends the first bone also ; and it extends the wrist, and by its oblique direction, contributes to supination. C. Extensor tertius pollicis.—This which bends the third joint is called in common the extensor longus pollicis. And here is a third muscle, which, in form, and place, and function, corresponds with the two former ones. Its origin is from the ridge of the ulna, and from the upper face of the interosseous membrane : and it is a longer muscle than the others ; for it begins high, near the top of the ulna, and continues the whole way down that bone, and is very fleshy and thick. It is penniform all the way down to the ligament of the wrist; and its small tendon passes the ligament in a peculiar ring. This tendon appears split, like those of the fingers ; it goes along the ulnar side of the first bone of the thumb, reaches the second, and is implanted there by a small slip of tendon; and being expanded, it still goes forward, to be inserted once more into the third bone of the thumb at its' root. Its use is evident after describing the others ; for we have only to add another joint for motion. It moves the last joint of the thumb, then the second, then its metacarpal bone upon the carpus ; and if that be held firm, it will extend the carpus * and it will, in its turn, contribute to supination, though in a less degree than the others. CI. Indicator.—The extensor indicis proprius has MUSCLES OF THE ARM, &C. 171 very nearly the same origin, and exactly the same course with me last, and lies by the side of it. Its origin is from the ulna, by the side of the extensor longus pollicis. It has also some little attachments to the in- terosseous membrane. It, like the others, is feathered with fibres in an oblique direction down to the ligament of the wrist. This muscle lies under the extensor communis digitorum ; its tendon passes along with the common tendon, through the annular ligament; and near the top of the metacarpal bone, or about the place of the common junctions of all these tendons, this one joins with the indicator tendon of the common ex- tensor. Its use is to extend all the three joints of the fore-finger, assisting the common extensor to point with that finger, to act independently of the common extensor, and to help to extend the wrist when the fingers are closed. CI I. The supinator brevis is an internal muscle, which forms, with the muscles of the thumb, of the fore-finger, and mid-finger, a kind of second layer; and this one lies con- cealed, much as the pronator quadratus does, on the inner side of the fore-arm. It is a short muscle, but very thick and fleshy, and of great power. It arises from the outer tubercle of the os humeri, and from the edge of the ulna, and from the interosseous ligament: it is then lapped over the radius, and is inserted into its ridge ; so that this supinator brevis is very directly opposed to the pronator teres, the insertion of the two muscles almost meet- ing on the edge of the radius. It is almost circumscribed to one use, that of performing the rotation of the radius out- wards ; but perhaps it may also have some little effect in ex- tending the ulna and in assisting the anconeus, MUSCLES SEATED ON THE HAND. Besides those muscles which bend and extend the fingers, there are other smaller ones seated on the hand itself, which are chiefly for assisting the former, and for quicker motions ; but most especially for the lateral motions of the thumb and little-finger ; and which are therefore named adductors, abductors and flexors, of the little-finger and thumb. That they are chiefly useful in assisting and strengthening the larger muscles, is evident from this, that much power being required for flexion, we find many of these smaller mus- cles added in the palm of the hand ; but as diere is little power of extension needed, little more than what will merely balance 172 MUSCLES OF THE ARM, &C. the power of the flexors, there are no small muscles on the back of the hand, the interossei externi excepted, which are chiefly useful in spreading the fingers. The short muscles in the palm of the hand are for bending the thumb, the fore-finger, and the little-finger: and the little- finger and the thumb have each of them three distinct mus- cles ; one to pull the thumb away from the hand, one to bend it, and one to pull it towards the hand, opposing it to the rest of the fingers, and so of the little-finger, which has also three muscles. ARRANGEMENT OF THESE MUSCLES. 1. Lumbricales, which bend all the fingers. "abductor pollicis, "") bending the thumb and carry- „ . flexor and opponens ling it away from the other fin- j pollicis, C" gers, or towards the palm of the ^adductor pollicis, J hand. „ f ") which carries the fore-finger to- 3. | abductor indicis, j wards the thumb# * r abductor minimi digiti,") which bend the little-finger, 4. J adductor minimi digiti, > and carry it like the thumb ^flexor minimi digiti, J outwards or inwards. {") which are small muscles, lying betwixt the interossei, i. metacarpal bones, and assisting the lum- J bricales in bending the fingers. All the muscles of the thumb are seated on the inside, to form the great ball of the thumb ; and it is not easy at first to conceive how muscles, having so much the same place, should perform such opposite motions ; yet it is easily explained by the slight variation of their places ; for the abductor arises from the annular ligament near the radius, and goes towards the back of the thumb. The flexor arises deeper from bones of the carpus, and from the inside of the ligament, and ♦ goes to the inside of the thumb. The abductor arises from the metacarpal of the mid-finger, and goes to the inner edge of the thumb. CIII. The abductor pollicis is covered only by the com- mon integuments. It begins a little tendinous from the out- side of the annular ligament, just under the thumb, and by some little fibres from the os scaphoides ; and from the tendon of the long abductor or extensor primus, it bends gradually round the thumb, and is at last inserted in the back of the first joint, just above the head of the metacarpal bone. But it does not stop here ; for this flat tendon is now expanded* into MUSCLES OF THE ARM, &C. 173 the form of a fascia, which, surrounding the first bone of the thumb, goes forward upon its back part, quite to the end, along widi the common tendon of the extensor. This muscle, like the others, is covered by a thin expansion from the tendon of the palmaris, as well as by the common integuments. Its only use is to pull the thumb from the fingers, and to ex- tend the second bone upon the first. Albinus describes a second muscle of the same name, having the same course, origin, insertion, and use: it also arises from the outer side of the ligament of the wrist, and is fixed into the side of the thumb, and lies upon the inside of the former muscle. These two are inserted into the first bone of the thumb; but the next is inserted into the metacarpal bone. CIV. The opponens pollicis, is often called the metacar- pal of the thumb. It is placed on the inside, and implanted into the side of the thumb : its office is to draw the thumb a- cross the other fingers, as in clenching the fist; and from its thus opposing the fingers, it has its name of opponens. It lies immediately under the last described muscle, and is like it in all but its insertion. It arises from the os scaphoides, and from the ligament of the wrist. It is inserted into the edge and fore part of the metacarpal bone of the thumb: and its use is to turn the me- tacarpal bone upon its axis, and to oppose the fingers ; or, in other words, to bend the thumb : for I can make no distinction. Therefore this muscle and the next, which lies close upon it, may be fairly considered as but two different heads of one thick short muscle. CV. The flexor brevis pollicis is a two-headed mus- cle, placed quite on the inside of the thumb, betwixt the fore- finger and the thumb, and extends obliquely across the two first metacarpal bones. It is divided into two heads by the long flexor of the thumb. The edge of this muscle lies in close contact with the edge of the last, or opponens; and indeed they may fairly be con- sidered as one large muscle surrounding the basis of the thumb. One head arises from the os trapezium or base of the thumb, and from the ligament of the wrist. The other head comes from the os magnum, from many of the other bones of the carpus, and from the ligaments which unite them. The first head is the smaller one ; it terminates by a pretty i onsiderable tendon in the first sesamoid bone. The second head runs the same course: it is implanted chiefly in the se- coriu sesamoid bone, and also into the edge of the first bone of 174 MUSCLES OF THE ARM, &C. the thumb close by it. The second head is exceedingly mus- cular and strong: the heads are completely separated from each other by the tendon of the flexor longus passing betwixt them. The office of this muscle is to bend the first joint upon the second, and the metacarpal bone upon the carpus : and indeed the office of this, and of the opponens, is the same. It is in the tendons of this double-headed muscle that the sesamoid bones are found. CVI. The adductor pollicis arises from the metacarpal bone of the middle-finger, where it has a flat extended base. It goes from this directly across the metacarpal bone of the fore- finger to meet the thumb. It is of a triangular shape, and flat: its base is at the metacarpal bone ; its apex is at the thumb: it is inserted into the lower part or root of the first phalanx : its edge ranges with the edge of the flexor brevis : it concurs with it in office ; and its more peculiar use is to draw the thumb to- wards the fore-finger, as in pinching. Thus do these muscles, covering the root of the thumb, form that large and convex ball of flesh which acts so strongly in al- most every thing we do with the hand. The ball of the thumb is fairly surrounded: it is almost one mass, having one office: but as the deltoides will, in some circumstances, pull the arm downwards, some portions of this fleshy mass pull the thunib outwards obliquely; some directly inwards : but the great mass of muscle bends the thumb, and opposes it to the hand ; and as this one muscle is to oppose the whole hand, the ball of flesh is very powerful and thick. The short muscles of the little-finger surround its root, just as those of the thumb surround its ball. CVII. The abductor minimi digiti is a thin fleshy mus- cle, which forms the cushion on the lower edge of the hand, just under the little-finger. It is an external muscle : it arises from the os pisiforme, and from the outer end of the annular ligament. It is inserted laterally into the first bone of the little- finger ; but a production of it still goes forward to the second bone of the little-finger. Its use is to spread the little-finger sidewise, and perhaps to assist the flexors. CVIII. The flexor parvus minimi digiti is a small thin muscle which rises by the side of the last, and runs the same course, with nearly the same insertion. Its origin is from the ligament of the wrist, and in part from the crooked process of the cuneiform bone. Its use is to bend the little-finger. And indeed the office and place of both is so much the same, that I have marked the last as a flexor ; and MUSCLES OF THE ARM, &C. 175 the little difference there is, is only that this perfomis a more direct flexion. CIX. The adductor minimi digiti is sometimes called the metacarpal of the little-finger. It lies immediately under the former muscle. Its origin is from the hook of the cuneiform bone and the adjoining part of the carpal ligament. It is inserted into the outside of the metacarpal bone, which it reaches by turning round it. Its use is to put the little-finger antagonist to the others: it is to this finger what the opponens is to the thumb. It also, by thus bending one bone of the me- tacarpus, affects the whole, increases the hollow and external convexity of the carpus, and forms what is called Diogenes's cup. CX. The abductor indicis is a flat muscle of considerable breadth, lying behind the adductor pollicis, and exacdy resem- bling it, being like the second layer. It arises from the os tra- pezium, and from the first bone of the thumb ; and it is insert- ed into the back part of the first bone of the finger, and pulls the fore-finger towards the thumb. The interrossei are situated betwixt the metacarpal bones. They are small, round, and neat, something like the lumbri- cales in shape and size. Three are found in the palm, which bend the fingers, and draw their edges a little towards die thumb ; four are found on the back of the hand, for extending the fingers. CXI. The interossei interni arise from betwjxt the me- tacarpal bones. They are also attached to the sides of these bones. They send their tendons twisting round the sides to the backs of these bones ; and they are inserted along with the tendons of the lumbricales and extensors into the back of the finger. They are thus flexors of the first joint, and extensors of the second joint, as the lumbricales are. CXII. The interossei externi are four in number. They arise, like the interni, from the metacarpal bones and their interstices, and from the ligaments of the carpal bones. They are peculiar in having each two heads, therefore named interossei bicipites. They join their tendons to those of the extensor and lumbricales : they have therefore one common office with them ; that is, extending all the joints of the fingers. Many have chosen to describe the origin and insertion with most particular care, marking the degree of obliquity, and as- certaining precisely their office, and giving particular names to each, as prior indicis for the first external: all which I forbear mentioning, because dieymust be more liable to perplex than likely to assist the student: if we but remember their common place and office, it is enough. The tendons of the flexor mus- 176 MUSCLES OF RESPIRATION. cles bend round the finger, along with the interossei and lum- bricales, for a surer hold ; consequently the tendons ot the long flexors, of the lumbricales, of the interossei interni, ot the ex- tensors, and of the interossei externi, meet upon the backs of the fingers ; which are by them covered with a very strong web of tendinous fibres. CHAP. IV. MUSCLES OF RESPIRATION ; OR, OF THE RIBS. JL HE whole back is clothed with strong muscles ; and all its holes, irregularities, and spines, are crossed with many smaller ones. These muscles are related either to the arm, to the ribs, or to the spine, i. e. the vertebra, whose motions they perform; and from this we obtain an arrangement not incon- sistent with the regular order of their office, and yet correspond- ing with the best order of dissection. The first or uppermost layer of muscles, viz. the trapezius, the musculus patientise, the rhomboides, the latissimus dorsi, belong to the arm. The serrated muscles, which lie next un- der these, are the muscles of respiration, and belong to the ribs: while the splenius and complexus, the muscles of the neck, the longissimus dorsi, sacro lumbalis, and the quadratus lumborum, which are muscles of the back, and the innumera- ble smaller muscles which lie betwixt the vertebrae, belong en- tirely to the spine. Respiration is indeed performed chiefly by the muscles of the belly, that is, in ordinary and easy breathing. In high breathing, the difficulty is relieved by the co-operation of al- most all the muscles of the trunk ; of which there is scarcely one that may not assist in some slight degree. But yet the muscles of the abdomen have many other offices. And the muscles of the spine, and of the scapula, again, belong properly to the arm and trunk ; and therefore I call those the muscles of respiration by which the ribs are moved in breathing, and which have no direct relation to almost any other motion but merely that of the ribs. The muscles which are appropriated to the ribs, performing no other motion, are, OB, OF THE RIBS. 177 _, *| which comes from the neck, 1. The serratus posticus I and lies fleshy over the ribs, to superior, J pull them upwards. -» which comes from the lumbar 2. The serratus inferior j vertebra, and lies flat on the posticus, {lower part of the back, to pull J the ribs downwards. "J which are twelve flat muscles, ,, ™ „ ! arising from the transverse pro- 3. The LEVATORES COSTA- ^ J each vertebra, and going RUM> S down to the rib below, they J raise the ribs. ""] which lie betwixt the ribs, and 4. The intercostal mus- I fill up all the space betwixt rib cles, ■ and rib; they also raise the J ribs. And there may be added to these, that muscle which, lying under the sternum and within the thorax, is called triangularis sterni, and pulls the ribs downwards. CXIII. The serratus superior posticus lies flat upon the side of the neck, under the trapezius and rhomboides, and over the splenius and complexus muscles. It arises by a flat and shining tendon from the spines of the three lower vertebrae of the neck and the two uppermost of the back. It goes oblique- ly downwards under the upper corner of the scapula, and is in- serted into the second, third, and fourth ribs, by three neat fleshy tongues. The ligamentum nuchse is chiefly formed by the meeting of the trapezii muscles; and the flat tendons of these upper serrat- ed muscles help to form it. They are purely levators of the ribs: their effect upon the vertebrae, if they have any, must be very slight. CXIV. The serratus inferior posticus is a very broad, thin, muscle, situated at the lower part of the back, under the latissimus dorsi, but above the longissimus dorsi muscle. It arises in common with the latissimus dorsi, from the spines of the two or three lower vertebrae of the back, and the three or four uppermost vertebrae of the loins. Their origin, like that of the latissimus, is by a thin tendinous expansion : it soon becomes fleshy, and, dividing into three, sometimes four, fleshy straps or tongues, each of them is inserted separately into the ninth, tenth, eleventh, and twelfth lower ribs, near their cartilages. So that this muscle, spreading so wide out from the centre of motion, has vast power; for it has the whole length of the rib as a lever. Its office is to pull the ribs dowmwards and backwards ; the Vol. I. Z 178 muscles of respiration, effect of which must be to compress the chest, and in certain circumstances to turn the spine. CXV. The levatores cost arum are twelve muscles on each side, for the direct purpose of lifting the ribs ; they lie above or upon the ribs, at their angles, and are thence named by some supra cost ales. They are almost a portion of the external intercostal mus- cles. The first of the levators arises from the transverse pro- cess of the last vertebra of the neck, and goes down to be insert- ed into the first rib, near its tuberosity; and so all that follow arise from a transverse process, and go to the rib below, being very small and tendinous at either end. But the three last le- vators arise from the second process above the rib to which they belong. They pass one rib to go into the one below it: they are consequendy twice as long as the nine first are ; and are therefore named levatores costarum longiores from the ninth downwards. Thus the levatores costarum are a succession of small mus- cles, arising from the transverse processes of the vertebrae, and going to the angles of the ribs ; beginning from the last verte- bra of the neck, and ending with the last but one of the back. They lie under the longissimus dorsi and sacro lumbalis ; and often they have connections with these muscles, sometimes very close. CXVI. The intercostales aretworows of muscles which lie betwixt the ribs: one row is external, the other internal. The external intercostals run from the spine towards the sternum, having their fibres directed from behind forwards, and stopping at the cartilages of the ribs. The internal, again, begin from the sternum, and go towards the spine ; they have their fibres directed backwards, and they stop at the angle of the ribs ; the reason for which might be given, were it worth our while to stop for an explanation. These two rows were thought to antagonize each other; the one to pull the ribs downwards, the other to raise them. But I shall not stop to explain this, nor to refute it; it is sufficient to declare their true use, which is (both external and internal) to raise the ribs and assist inspiration*. The ninth, tenth, eleventh, and twelfth ribs, have a freer mo- tion ; and it appears to me that this is the true use of the leva- tores longiores ; and for the same reason we find, that from th« *' I remember, many years ago, to have heard Dr. Monro explain the office oi the intercostal muscles by a diagram, deducing from that argument, the more powerful effect of all muscles having oblique fibres. or, of the bibs, 179 sixth rib and downwards there are certain slips of the internal intercostals, which pass over one rib and go to the second be- low ; and as the levatores longiores were called supra-costales, these have been named infra-cost ales, and costarum de- Pressores proprii. They were discovered by Verhein, and bear his name : they were explained as depressors of the ribs by Haller; but they are little different from the intercostals in form, and not at all in office, for they raise the ribs along with the intercostal muscles. CXVII. The triangularis sTERNi,or sterno costalis, is a depressor of the ribs ; an internal muscle lying chiefly on the inner surface of the sternum,and on the cartilages of the ribs. It is very generally considered as a triangular muscle on each side, but some consider it as three or four muscles under the title of sterno-costales. There are four slips lying on the cartilages of the third, fourth, fifth, and sixth ribs. The lower portion of the triangu- laris arises from the ensiform cartilage, and is inserted into the third or fourth rib ; the third arises from the middle of the sternum, and goes off from the edges of that bone to be insert- ed into the third rib. The fourth or uppermost portion is often wanting; it goes off in part also from the inner surface of the sternum, but more commonly from the third rib, and goes to the second rib. In a dog they are much larger than in a man. Their office is to depress the ribs. And these portions are all conjoined at their roots, which gives the whole muscle the triangular shape. The true uses of the intercostales, subcostales, and triangu- laris sterni, have been disputed; but if the first rib be more fix- ed than the other ribs, then the intercostals proceeding down- wards from the first rib must raise all the thorax ; and if the sternum be more fixed than the ribs, then the stemo-costales muscles going upwards from the sternum must pull down the ribs. ( 180 ) CHAP. V. MUSCLES OF THE HEAD, NECK AND TRUNK. MUSCLES OF THE HEAD AND NECK. JL HE serratus superior posticus being raised, the splenii come into view ; and the splenii being also lifted, the com- plexus is fully exposed. CXVIII. Splenius.—The two splenii are so named from their lying like surgical splints along the side of the neck ; both together they have the appearance of the letter Y ; the com- plexus being seen betwixt them in the upper part of the angle. They lie immediately under the trapezii, and above the com- plexi. Each splenius is a flat and broad muscle, which arises from the spinous processes of the neck and back, and is implanted into the back part of the head. It arises from the four spines of the back and the five lower of the neck ; it parts from its fellow at the fifth vertebra of the neck, so as to show in the in- terstice two or three of the uppermost spines of the neck, with the upper part of the complexus muscle : each splenius goes obliquely outwards, to be inserted into the occipital ridge, and all along to the root of the mastoid process. At the third vertebra of the neck, where the two splenii muscles part from each other, the tendons of the opposite splenii are closely con- nected both with each other, and with the common tendon, which is called ligamentum nucha. This is the splenius capitis ; but there is a portion of this same muscle which lies under this, and which has the same common origin, but which terminates by four or five distinct tendons in the transverse processes of the upper vertebra of the neck. This portion may be dissected apart; and has been considered by many as a muscle, the splenius colli of Al- binus ; who has distinguished as splenius capitis all that part arising from the spines of the neck, and implanted into the head, and as the splenius colli, all that part which arises from the vertebra of the back, and is implanted into the transverse processes of the neck. These splenii are the proper antagonists of the mastoid muscles. Both the splenii acting, pull the head direcdy back- MUSCLES OF THE, ckc. 181 wards; one acting turns the head and neck obliquely to one side ; one acting along with the corresponding mastoid mus- cle, lays the ear down upon the shoulder. CXIX. The complexus is named from the intricacy of its muscular and tendinous parts, which are mixed; from the ir- regularity of its origins, which are very wide, it has the names of complexus-implic atus-trigeminus, by which the student is warned of the difficulty of understanding this muscle. It lies immediately under the splenius; arises by distinct tendons, with ten or more tendinous feet, from the transverse processes of the neck and back, from the four lower vertebra of the neck, and from the seven uppermost of the back ; having also some less regular origins, as from two spines of the back, and from four oblique processes in the neck. It grows into a large muscle, which is not like the splenius, flat and regular, but thick, fleshy, composed of tendon and flesh mixed; fil- ling up the hollow by the sides of the spines of the neck, and terminating in a broad fleshy head, which is fixed under the ridge of the occipital bone; and this is, the part which is seen in the angle or forking of the splenii. This may stand as the general description of the muscle considered as one : but Albinus has chosen to describe it as two muscles, under two different names, with a minuteness which, far from clearing the demonstration of any difficulties, makes it less distinct; and, if any thing could complete the confusion, it was his humour of calling that bi venter which had been hitherto named complexus, and naming the lower part of the muscle complexus, though it never had been distinguished from the rest. The biventer of Albinus is the upper layer of the mus- cle, that part which appears in the fork of the splenii: and if we have hitherto named it complexus, from its mixture of tendons and flesh, it is particularly improper to transfer that name to another part of the muscle which is less complicated. This upper layer, the biventer cervicis, arises by a large broad head from the occipital bone. In the centre of this belly there is a confusion of tendon; then there is a middle tendon, about the middle of the arch of the neck ; and the lower part of the biventer arises from two parts ; first, by one slip of flesh from the two uppermost spines of the back ; and, secondly, by a larger fleshy portion which comes from the fourth, fifth, sixth, and seventh transverse processes of the back. And it is from the upper and lower fleshy heads, and the confused middle tendon, that it is called biventer. The complexus of Albinus lies below this one. It arises by three tendinous and fleshy slips from the three upper trans- 182 MUSCLES OF THE verse processes of the back: then it has four other slips from four oblique or articulating processes of the neck ; which various origins are gathered into one thick irregular fleshy belly, which is implanted into the occiput under the great head of the biventer, and mixed with it. This I have chosen to explain, lest the student should be embarrassed by false names ; referring him to the first paragraph for the true and simple description of this muscle. CXX. Trachelo-mastoideus*.—The last muscle is often named complexus major, and this complexus minor; but a fitter name is the trachelo-mastoideus, from its origin in the neck and its insertion in the mastoid process. It has exactly, or nearly, the same origin and the same in- sertion with the splenius; for it arises, not from the spines indeed, but from the transverse processes of the back and neck, and is implanted into the mastoid process. Its origin is from the three first vertebra of the back, and from the five lowest of the neck at their transverse processes. Its origins are by distinct tendons, and its belly is in some de- gree mixed of tendon and flesh; whence its name of complexus minor. It is inserted into the mastoid process, just under the insertion of the occipital part of the splenius : and indeed its long and flat belly lies all along under that muscle, so that the order is this : 1. The trapezius ; 2. The splenius capitis; 3. The splenius cervicis ; 4. The Trachelo-mastoideus. It is needless to speak of its use, since the use of all these muscles is to draw the head backwards directly, when both act; obliquely, when one acts alone. The recti muscles are two deep-seated muscles, which go immediately from the vertebra to the occiput to be inserted into its lower ridge. They are called major and minor. CXXI. The rectus minor is the shorter of the two, arising from the first vertebra of the neck. Its place of origin is a small tuber which stands in the place of the transverse process of the first vertebra ; and from that point where it is tendin- ous, it goes up to the occipital ridge, and is inserted fleshy. CXXII. The rectus major is larger. It rises, in like manner, tendinous, from the second vertebra of the neck at its transverse process, and mounting from that, is inserted fleshy into the lower ridge of the occiput without the former. These * It is the TRACHELO-MASTOIDEUS, the MASTOIDEUS LATERALIS, the CAPITIS partertius, the complexus minor : by some it is considered as a part of thc COMPLEXUS. HEAD AND NECK. 183 are so placed, that the recti minores appear in the interstice of the recti majores. And though we call them both recti, yet they cannot truly be so ; for the recti minores must be, in some degree, oblique, and the recti majores still more so : and con- sequently, although their chief use be conjointly to draw the head directly backwards, yet one acting must turn the head to its side. And indeed the same may be said of all the muscles of the neck ; for they are all divided by the spine, and conse- quently they are all oblique. The obliquus superior and obliquus inferior corres- pond very closely in all things with the recti; but in their ob- lique direction the uppermost, as being much shorter, has been named obliquus minor, the lower one obliquus major. CXXIII. The obliojjus superior arises from the trans- verse process of the atlas, and is inserted into the end of the lower occipital ridge. Its use, notwithstanding its oblique position, is not to turn, but to bend, the head backwards ; for die occipital condyles are not concentric circles. Its insertion into the occiput is under the splenius and complexus ; but one edge of it is above the insertion of the rectus major. CXXIV. The obliojjus inferior rises from one vertebra and goes to another. It arises from the spine of the second vertebra: it goes to the transverse process of the first; and it meets the superior oblique muscle ; and, by the long lever or arm of the first vertebra, obtains great power. The first vertebra or atias rolls on the tooth-like process of the dentatus; and while the great and slow motions of the neck in general are performed by other muscles, the short and quick turnings of the head are performed entirely by these oblique muscles. MUSCLES OF THE TRUNK. The great muscles which move the back and loins are the QUADRATUS LUMBORUM, SACRO LUMBALIS, and LONGISSI- MUS DORSI. The sacro lumbalis and longissimus dorsi lie immediately under the latissimus dorsi, which is the outer layer ; the •quadratus lumborum lies again under these, and next to the abdominal muscles ; and, lastly, the abdominal muscles are •the innermost layer, and make the back part of the walls of the abdomen. Although the quadratus lumborum lies deep under the longissimus dorsi muscle, I shall describe it first for the sake of a connection which will be presently understood. CXXV. The ojjadratus lumborum is a flat squared mus- cle, named quadrants from its square or rather oblong form. 184 muscles of the trunk. It arises fleshy from three or four inches of the back part of the os ilium, and from the ligaments of the pelvis, which tie the back part of the ilium to the side of the sacrum and to the transverse processes of the loins. As it goes upwards along the side of the lumbar vertebrae, it takes hold of the points of the transverse processes of each by small tendinous slips ; so that we are almost at a loss whether to consider these as new origins or as insertions: but its chief insertion is into the lower edge of the last rib, and a small production of it slips under the arch of the diaphragm, to be implanted into the body or fore part of the last vertebra of the back. The longissimus dorsi and sacro lumbalis have their origin in one common and broad tendon, coming from the sa- crum, ilium, and loins ; the two muscles lie along side of each other; the longissimus dorsi is nearer the spine, and keeps its tendons closer by the spine. The sacro lumbalis is farther from , the spine, and spreads its tendinous feet broader upon the sides of the thorax ; and if one be a little under the other, it is the outer edge of the longissimus dorsi, which is a little under the edge of the lumbar muscle. The common tendon and muscle (for there is for some way but one muscle) begins thus : it may be said to have two kinds of adhesion ; for, first, externally it appears a broad, flat, and shining tendon, which arises tendinous from all the spines of the lumbar vertebrae, from the spines of the sacrum, and from the back part of the os ilium. But the inner surface of this broad tendon is strongly fleshy ; for it arises fleshy from the back part of the ilium, from the deep hollow betwixt the ilium and sacrum, from the sides of the long spines of the lumbar vertebra, and from their articulating processes and the roots of their transverse processes. In short, its origin is all tendin- ous without, and all fleshy within ; and its flesh arises from all that irregular surface which is on either side of the spine, be- twixt the os ilium and the vertebra of the loins ; and thus it continues one strong tendinous and fleshy muscle, filling up all the hollow of the loins. There is an appearance of separation, something like a split in the tendon, which shows in the loins what part of the tendon belongs to each muscle ; but it is only in the back that they are fairly divided. Just opposite to the lowest rib, the longissimus dorsi and sa- cro lumbalis break off from the common tendon ; and the lon- gissimus goes to be implanted into the vertebra, and the sacro lumbalis to be implanted into the ribs. % CXXVI. The longissimus dorsi is a muscle of the spine. It is not a flat muscle, but round, thick, and firm, filling up all the hollow betwixt the spine and the angle of the ribs. It is of muscles of the trunk. 185 a long form, as its name implies, terminating towards its top almost in a point. It has two distinct sets of feet by which it is inserted ; one set of feet more fleshy, but small and neat, go outwards from the side as it were of the muscle, to be implant- ed near the heads of the ribs ; the lower ones farther out than the heads of the ribs ; the upper ones close to the head, and consequendy closer to the spine. These heads are nine or ten in number, corresponding with the nine or ten uppermost ribs. Another set of heads, which are not so well seen as this set, because they lie more under the muscle, are small, neat, and tendinous; they go in an opposite direction, viz. inwards and upwards ; keep closer by the spine, and are inserted into the transverse processes of the vertebra of the back. This set of heads is thirteen in number, implanted into the transverse pro- cesses of all the back, and of one vertebra of the neck. CXXVII. The sacro lumbalis separates from the lon- gissimus dorsi at the last rib, and is a flatter and less fleshy muscle : its twelve tendons are flatter than those of the lon- gissimus dorsi, and go out wider from the spine. The tendons next to the longissimus dorsi run highest up, and are the long- est ; those farthest from the spine, i. e. farthest out upon the chest, are the shortest. It has a flat tendon for each rib, which takes hold upon the lower edge of the rib. But it has another order of small muscles which mix with it: for as the longissi- mus dorsi has a double row of insertion, this has another set of attachments ; for there arises from the surface of each rib, at least of the six or seven lowest ribs, a small slip of flesh, which runs into the substance of the sacro lumbalis, and mixes with it; and these fleshy slips go by the name of the additamen- tum AD SACRO-LUMBALEM, Or MUSCULI ACCESSORII. Both these muscles, viz. the longissimus and sacro lumbalis, terminate in points which reach towards the neck ; and under the point of each there lie the roots of two small muscles, which go up to move the neck. Many have referred these slips go- ing up into the neck entirely to the muscles I am now describ- ing; calling one an ascending slip of the longissimus dorsi, and the other a slip of the sacro lumbalis ; while others have des- cribed them as distinct muscles, having but slight connections with the longissimus and sacro lumbalis. Their proper names are cervicalis descendens, and transversalis colli. CXXVIII. The cervicalis descendens is connected with the sacro lumbalis muscle; it cannot be entirely referred to it, for the cervicalis descendens arises as a distinct muscle from the five lower vertebra of the neck at their transverse pro- cesses ; goes downwards vcrv small and slender to be inserted Vol. I. 2 A 186 muscles op the trunk. into the six uppermost ribs, to get at which it slips under the longest tendons of the sacro lumbalis ; but that the cervicalis descendens does not belong to the sacro lumbalis, may be inferr- ed from its having distinct tendons from six ribs, and from six transverse processes of the neck, and from these tendons being in a direction which does not at all correspond with the heads of the sacro lumbalis. Indeed the longissimus dorsi has a better claim to this muscle ; for a long slip, partly tendinous and partly fleshy, runs upwards from the longest tendon of the longissimus dorsi, to join itself to the cervicalis descendens.* CXXIX. The trans vers alis colli is that which Sabba- tier refers to the longissimus dorsi ; but it is a distinct muscle, arising partly tendinous and partly fleshy from the five upper transverse processes of the back ; lies betwixt the trachelo mastoideus and the cervicalis descendens ; goes from the transverse processes of the back to the transverse processes of the neck, and has no more than a confused and irregular con- nection with any other muscle. The quadratus lumborum keeps the trunk erect by the action of both muscles at once ; inclines it to one side, or turns it upon its axis, when one only acts ; and by its insertion into the ribs must assist in high breathing, by pulling down the ribs. The longissimus dorsi has no power but over the spine, which it bends backwards, acting continually in keeping the trunk erect. This is also the chief use of the sacro lumbalis; but the sacro lumbalis going out further upon the ribs, takes such hold upon them, that besides its common action of raising the trunk, it may, on occasions, pull them down, assist- ing the quadratus and the lower serrated muscle. And it will have greater power in turning the trunk of the body upon its axis than the longissimus dorsi, which pull almost direcdy backw.ards. The cervicalis descendens co-operates with the trachelo mastoideus and others, which turn the head to one side ; and the cervicalis descendens bends the neck to one side ; both the one and the other being independent muscles, and having no further connection with each other than what arises from the confusion of the parts. * Hence it is plain that the sacro lumbalis and longissimus dorsi have nearly an equal claim to the cervicalis descendens. Tor, first, the longissimus dorsi sends its longest tendon fairly up into the cervicalis descendens so far, that the slip is im- planted into the transverse processes of the neck. And, secondly, the feet of the cervicalis descendens begin under the last tendons of the sacro lumbalis, so as to have the appearance of arising from its supplementary muscle, the additamentum, and being part of it; and indeed Sabbatier has described it according to this view. MUSCLES OF THE TRUNK. 187 These two muscles bring us to mention that intricate set of muscles which fills up all the hollows and interstices amqng the spines and irregular processes of the vertebra, which might be fairly reckoned as one muscle, since they are one in place and in office ; but which the anatomist may separate into an infi- nite number, with various and perplexing names ; an opportu- nity which anatomists have been careful not to lose. The surface of the back, from the bulge of the ribs on one side to the bulge of the ribs on the opposite side of the thorax, is one confused surface ; consisting of innumerable hollows, processes, and points of bone; and it is tied from point to point with innumerable small muscles, or unequal bundles of mixed tendon and flesh. There are many points ; as die spi- nous, transverse, and oblique processes of the vertebra, and the bulging heads and angles of the ribs ; and each process, or at least each set of processes, has its distinct sets of muscles and tendons. 1. There is one long continuity of muscular and tendinous fibres going from spine to spine, along the whole length of the back and neck. This is divided into the spinalis cervicis and the spinalis dorsi. 2. There is a similar continuation of fibres, with less tendon and more flesh, belonging one half to the spine and the other half to the transverse processes, where it is named semi- spinals dorsi. 3. There is a great mass lying all along the hollow of the back, on each side of the spinous processes, which passing alternately from the transverse process of one vertebra to the -. spinous process of the next above, is of course split into many heads, but yet having such connection as to give it the form and name of a single muscle, the multifidus spin/E. 4. and 5. There are yet smaller muscular fasciculi, which stand perpendicularly betwixt every two transverse and every two spinous processes ; thence they are named intertrans- versarii and inter-spinales. CXXX. The spinalis cervicis is that which is implanted into the spines of the cervical vertebra; but because it does not go from spine to spine, like the spinalis dorsi, but from transverse processes to spines, it has been named by Winslow semi-spinalis, or transverso-spinalis colli. It arises from the transverse processes of the six upper vertebra of the back, and is inserted into all the spinous processes of the ver- tebra of the neck except the first and last; and it extends the 188 MUSCLES OF THE TRUNK. neck, or, by its obliquity, may contribute to the turnings of the neck, or to bending it to one side*. CXXXI. The spinalis dorsi arises from two spinous pro- cesses of the loins, and from the three lower spines of the back ; and passing two spines untouched, it is implanted into all the spines of the back except the uppermost. This muscle is very slender and long, and consists fully more of tendon than of flesh: it has five feet below, rising from the lower spines of the back and loins ; and nine feet above, implanted into the upper spines of the back. Its action must raise the spine ; but perhaps it may be equally useful as a muscular and tendinous ligament. CXXXII. The semi-spinalis dorsi arises from the trans- verse processes of the lower vertebra of the back all but two ; and is implanted into the upper spinous processes of the back, and into the first spine of the neckf. CXXXIII. The multifidus spinas runs from the sacrum along all the spine to the vertebra of the neck ; and is a com- prehensive and true way of describing many irregular portions of flesh, which authors have divided into distinct muscles}:. It is a continued fleshy indentation, from transverse process to spine, through all the vertebra of the back, neck, and loins. It begins both tendinous and fleshy from the upper convex surface of the os sacrum, which is rough with spines from the adjoining part of the ilium ; and in the loins it arises from ob- lique processes ; in the back, from transverse processes ; and again from oblique processes among the cervical vertebra. Its origin in the loins is close to the spine ; being from the upper oblique processes, and from the root of the transverse processes. In the back it arises from the transverse processes, and therefore arises there by more distinct heads. In the neck, again, it arises from the lower oblique processes more confusedly. Its bundles or fasciculi are inserted into the spinous pro- cesses ; sometimes into the second, or even into the third or fourth spine, above that from which the bundle arises ; for the tendons do not stop at that spinous process which they first * The tramsversalis cervicis (vide p. 186.) is that which goes from the transverse processes of the back to the transverse processes of the neck; while this, the spinalis cervicis, goes from the transverse processes of the back to thc spines of the neck. f This is of course the transverso-spinalis dorsi of Winslow. i Transverso-spinalis lumborum veterib. sacer; semi-spinalis* in- ternus, five transverso-spinalis dorsi ; semi-spinalis, five transverso- spinalis colli, pars interna.—Winslow. Transversalis lumborum, vulgo sacer; transversalis dorsi ; transversalis colli__Douglas. MUSCLES OF THP TRUNK. 189 touch, but go upwards, taking attachments to other two or three, and mixing their tendons with those of the fasciculi above and below; and these tendons reach from the first of the loins to all the vertebra, up to the adas, which is the only one not included. The use of the multifidus spina is to retain the spine from being too much bent forwards ; for these muscles serve (as I have observed) the purpose of a ligament, and the best of all ligaments, having a degree of strength exacdy proportioned to the necessity for strength. It also moves the spine backwards, though perhaps it is less useful in this than as a ligament; for we find it as strong in the vertebra of the back, which have little motion, and that little very slow and general. It seems rather intended to moderate the lateral motions of the vertebra than to produce them : when it acts, its chief use is either to resist the spine being bent forward by a weight, or to erect the spine. CXXXIV. The interspinales colli, dorsi, and lum- borum, have varieties so litde interesting that they need hardly be described. The interspinales colli are stronger, be- cause the neck has many and quick motions, and the bifurcated spines of the neck give broader surfaces for these muscles. The interspinales dorsi are almost entirely wanting, be- cause the spines of the back are close upon each other, and the vertebra are almost fixed. The interspinales in the loins are rather tendons or ligaments than proper muscles. CXXXV. The intertransversales are again stronger and fuller in the neck, because of the lateral motions of the neck being free, and its transverse processes forked. They are in more numerous bundles where the motion is greatest, viz .betwixt the atlas and dentatus; and it is there that Albinus counts his intertransversales cervicis, priores-late- rales, &c. The inter-transversarii are wanting in the back, giving place to the ligaments, by which they are tied to each other and to the ribs ; but in the loins, the inter-transversarii are again strong, for the lateral or twisting motions of the loins. The muscles on the fore part of the head and neck will com- plete the catalogue of those belonging to the spine, and thev are the chief antagonists to the muscles which I have been describing. CXXXVI. The platisma-myoidesj is a very thin muscu- f ThevLATisMA-MYoinEs is also named muscplu* cutaneus latissimus colli, and ojjaoratus gen^:. 190 MUSCLCS OF THE TRUNK. lar expansion, like the cutaneous muscle in animals. It is spread over the other muscles immediately under the skin, and covers the whole neck and lower part of the face. It arises from the cellular substance and aponeurosis, which cover the pectoral muscle, the deltoid muscle, and the clavicle. Its origin is by long separate fleshy slips ; it goes like a thin in- tegument over the neck, and is first inserted about the depress- or anguli oris ; and then going over the masseter, is lost betwixt the muscles and the integuments of the cheek. Perhaps it serves also to pull down the skin of the cheek and the angle of the mouth ; but its chief insertion is into the lower jaw, and its use to pull it downwards. CXXXVlI. Mastoideus.—This muscle arises partly from the clavicle, partly from the sternum. Albinus reckons it two muscles, the sterno-mastoideus, and cleido-mastoideus: a more common name is the sterno-cleido mastoideus: but here, as in other things, I adhere to what is plainest. And the most familiar and easy name is musculus mastoideus, considering the clavicular portion as an addition only. Its origin from the upper part of the sternum is pretty round. It arises again flat from the fore part of the clavicle : and this second origin is broad and fleshy, while the first one is tendi- nous and pointed. These two heads form together a very big strong, bellied, fleshy muscle, which is inserted into the mas- toid process by a broad tendon, which indeed surrounds the mastoid process, and from that extends still backwards towards the lamdoidal suture. When one of the mastoid muscles acts, it turns the head to one side ; when both act, they pull the head directly forwards. CXXXVIII. Rectus internus capitis major. There are three muscles on each side, lying under the oesophagus, trachea, and great vessels, flat upon the fore part of the verte- bra ; and this is the first and longest. Although this be called rectus, it is oblique, and runs rather on one side ; for it arises from the transverse processes of the five lower vertebra of the neck, and is inserted into the cunei- form processes of the occipital bone, just before the foramen magnum. CXXXIX. Rectus internus minor. This is an exceed- ingly small muscle ; resembles the obliquus posterior of the head. It lies immediately under the rectus major : it arises from the fore part of the body of the first vertebra, the atlas; and going (like the other rectus) obliquely inwards, it is insert- ed into the occipital bone near the condyle. CXL. And the rectus capitis lateralis is anodier small muscle like the former ; which arises from the transverse MUSCLES OF THE TRUNK. 191 processes of the first vertebra, and is inserted into the side of the cuneiform process of the occipital bone. It lies immediate- ly under the exit of the great jugular vein. CXLI. Longus colli. This is the chief of those muscles which lie upon the fore part of the neck ; it is very long, ari- sing from the flat internal surface of the vertebra of the back to go up along those of the neck. Its origin is first within the thorax, from the three upper- most vertebra of the back, from the flat part of their bodies, and then from all the transverse processes of the neck except the three upper ones. It is inserted tendinous into the fore part of the second vertebra of the neck, where the opposite large muscles meet in one point almost.* All these muscles, which lie thus flat upon the plain surface of the vertebra of the neck, pull the head and neck directly for- wards ; or when the muscles of one side act, they are of use in pulling it towards that side ; though I rather suppose that that motion is performed by the external muscles. CXLII. The scalenus I consider as one muscle ; for it is one in origin, insertion, and office. Its origin is from the whole upper surface of the first rib from its cartilage backwards, and also from the second rib ; and its insertion is into the trans- verse processes of the vertebra of the neck. But by its broad origin, and its very long insertion, it gives opportunity for di- viding it into several fasciculi; and accordingly it has been so divided: but these divisions are entirely modern, artificial, and unnatural. The ancients considered it as one triangular mus- cle : Winslow divided it into two, the primus and secundus ; Cowper into three ; Douglas into four ; and Albinus divides it into five muscles. The ancients called it scalenus from its resemblance to the scalen triangle ; and the true anatomy is to consider it as one great triangular muscle, flat, and stretching from the ribs to the neck, closing the thorax above, and giving passage to the nerves and vessels of the arm. If it were to be described in distinct portions, it would be in three parts. The anterior portion arises from the transverse processes of the six lower vertebra of the neck, and is inserted into the flat part of the first rib hard by its cartilage. The mid- dle portion from the four lower vertebra goes to the outer edge of the rib, and extends along all its-length. The posterior por- tion is the thinnest and longest; for it arises from the trans- verse processes of the second, third, and fourth vertebrae. It is inserted into the upper edp,-e of the rib, about an inch or more from its articulation with the spine. * The longus colli muscle is in part covered by the rectuj major. 192 MUSCLES OF THE ABDdMEN. The first head is tendinous and fleshy at its insertion into the rib ; but the second and third heads are tendinous both m their origins and insertions. The artery goes through the flesh of the first portion, about an inch above the axilla. The nerves pass in the interstice betwixt the first and second portions. The office of the scalenus muscle is to pull the neck to one side, or to bend the head and neck forwards when both act; and when the neck is fixed backwards, they may perhaps raise the ribs; for asthmatics are observed to throw the head backwards, in order to raise the chest with greater power. CHAP. VI. OF THE MUSCLES OF THE ABDOMEN, AND OF THE DIAPHRAGM. i- HE abdominal muscles cover in the belly, contain the bow- els, and take a firm hold upon the pelvis and the trunk ; the diaphragm, again, is a moving partition betwixt the thorax and the abdomen ; and the diaphragm pressing down the bowels upon the abdominal muscles, enlarges the thorax, and the ab- dominal muscles re-acting, push the bowels back upon the dia- phragm, and compress the thorax. Thus the alternate yield- ing and re-action of the abdominal muscles and diaphragm per- forms breathing ; agitates the bowels ; promotes the circula- tion ; expels the faces and urine ; assists the womb in the de- livery of the child. And, with all these important uses, the abdominal muscles bend and turn the trunk, and fix it for the stronger actions of the limbs. They steady the body in lifting weights, in bearing loads, in all our more violent exertions: they often give way under this double office of breathing and of straining along with the rest of the body ; and the bowels coming out through their natural openings, or by bursting through the interstices of their fibres, form herniae of various kinds. Whence the anatomy of these muscles is most interest- ing to the surgeon. The muscles of the abdomen are five on either side. 1. The outer oblique muscle, to which the names of descendens, decliyes, and major, are added, because it is the outermost AND OF THE DIAPHRAGM. 193 &{ all the abdominal muscles ; because it is the largest, cover- ing all the side of the abdomen with its fleshy belly, and all the fore part of the abdomen with its broad expanded tendon; and it is called declivis, or descendens, because its fleshy belly begins above upon the borders of the thorax; and because i both its muscular and tendinous fibres, which lie parallel to 'I each other, nm obliquely from above downwards and inwards. 2. The obliquus internus is named from its being within ' the first; and has the names of ascendens vel minor super- %• added, because its fleshy belly is smaller than that of the first, arises below, chiefly in the haunch-bone, and all its fibres go from below upwards. 3. The transversalis lies under all the others, and next , to the cavity of the abdomen, and has but one name, which , 1 also is derived from the direction of its fibres running across or round the abdomen. 4. The rectus, so named because of its running on the forepart of the abdomen in one straight line from the .pubis to the sternum. 5. The pyramidal muscle is the only one named from its shape. It is a small, neat, conical muscle, which arises from the os pubis by a broad basis, and has its apex turned upwards; but it is not always found, for it is only as a supplement to the recti muscles and a part of them ; whence it has been named musculus succenturiatus, or supplementary muscle. CXLIII. The external obliqjje muscle arises from the ribs, and, like all the others which "arise from ribs, is a serrated muscle. It comes from the eight lower ribs by distinct fleshy tongues, one from each rib. These serrae are mixed with the indentations of the serratus major anticus muscle, which goes off" in an opposite direction. The origin of the muscle lies out broad upon the border of the chest; it is its thickest and most fleshy part, whence its fibres go down all in one direction parallel with each other, but oblique with respect to the abdew men. Its fleshy belly ceases about the middle of the side. Its flat sheet of tendon goes over the forepart of the belly till it meets its fellow exacdy in the middle ; so that one half, or the back part of the abdomen, is covered by its fleshy belly, and the forepart by its tendinous expansion. The muscle meets its fellow in the middle of the belly; and this meeting fonns (along with the other tendons) a white line from the pubis to the sternum, which is named linea alba. It also, before it reaches the middle, adheres to the flat tendon of the inner oblique muscle. This meeting is about four inch- es on either side of the linea alba, and is a little inclined to the circular, whence it is named linea semilunaris. And, Vol. I. 2B 194 MUSCLES OP THE ABDOMEN, finally, this muscle is implanted into the spine of thc ilium j fleshy about the middle of the ilium; tendinous at the fore par or spinous process of the ilium ; and still tendinous into thj| whole length of that ligament, which Extends from the spine of the ilium to the crest of the pubis. This is the whole of its insertion, viz. all the length of the linea alba, from the pubis to the sternum, the forepart of the spine of the ilium, and the ligament of Paupart ; which^ though it is commonly thought to be but the tendon of the ex- ternal oblique stretching from point to point, is in truth a dis- tinct ligament, independent of the tendon, and stronger than it. CXLIV. Obliojjus internus abdominis.—The chief part of this muscle arises thick and fleshy from all the circle of the spine of the ilium, with its fibres directed upwards. But, to be accurate, we must describe it as arising from the whole length of the spine of the ilium ; from the joining of the ilium and sacrum ; from the spines of the sacrum itself; and from the three lower spinous processes of the loins* ; and, lastly, it arises from the ligament of the thigh, as its end next to the ilium ; but still the chief belly is at the iliac spine. From that it spreads upwards in a radiat,ed form ; the central fibres onlj are direct, going across the abdomen to the linea alba; tW higher fibres ascend and go towards the sternum, and tbi lower ones go obliquely downwards to the pubis. Its flat ten- don is like that of the external oblique ; and it is inserted into the cartilages of all the false ribs, into the sternum, and int< the linea alba through its whole length. CXLV. The transversalis abdominis runs direct across the belly. It arises fleshy from the inner surface of the six lower ribs, where its digitations mix with those by whicli the diaphragm arises tendinous ; from the transverse processu not through it. At the place where the cord passes tik -hr of the internal oblique muscle, it sends a bundle of fleshy fibre down along the cord, which go all along the cord, grq^uaJt extend towards the testicle, expanding and growing thji upo the upper end of the testicle, and gradually disappearing mi body. This is ■*' CXLVIII. The cremaster muscle of the te^tci"- which is a thin slip of fibres from the internal oblique muscle of the abdomen ; which is designed for suspending the t» ..tide, and for drawing it up; is very thick and strong in tK' l-^ver animals, as in bulls, dogs, &c.; is easily found in man, buwiot always, being sometimes thin and pale, and hardly to be know from the coats upon which it lies. It appears to grq^ mor fleshy in old age, and to be thickened in enlargement^ of the testicle, the better to support the weight. ■.,- 6. The ligament of the thigh* is a distinct ligamlm, and not merely the tendon of the external oblique, rounc d .sr.d turned in. It arises from the spinous process of the iii i,m, and is inserted into the crest of the pubis. It receives the external oblique muscle, for the tendon is implanted into it. P>'' t of j the flesh of the internal oblique muscle arises from tin »uteir end of the ligament. It forms an arch under which the psu:1--; and iliacus internus muscles, and the great artery of thc ihig and its anterior nerve, pass out. The great vein, and the lym- phatics of the limb, return under it to get into the abdomen ; the lymphatic glands of the groin lie there. The whole inter- stice is surrounded and filled up by cellular substance and uit but it is not firm ; the playing of the muscles, and the fat, and inguinal glands, keep it open and lax ; and at that point tht • This ligament of the thigh is named also the inguinal ligamjkt; thr/ crural arch: the ltgament of Paupart; the ligament of Fali«>hu>, &■:.' • AND OP THE DIAPHRAGM. 199 ^wels arc apt to fall down, especially in women, where the ine of the ilium is high and the arch wide. So little are ,_jnoryl'hernia or the form of this opening understood, that no articular cushion is adapted to this part ; for it is supported y the com non bandage for the hernia of the groin : and, a few cars ago, hernia of the groin was not even known by anato- ists of the highest name. For Cowper says (explaining a-apart'' "igament,) " It is not impossible but that ruptures may sc .times happen in this part ; and I am apt to imagine • I i s to the case when a rupture is very large, and not to be ■i mtc' by a truss." It ofte • happens, that in vomiting, in violent coughing, in ^training at stool, or in lifting heavy weights, these natural "ipenirgs are forced, and the bowels descend. The umbili- •s ve y seldom forced by sudden exertion, for it is a very .ing; but often it is slowly dilated in pregnancy; and :■ :uu c' the naval is infinitely more frequent with women than i men.—The opening of the ring is often kept dilated bv Ifth '<>road, and is for a very obvious reason stronger in man than in nimals. Some choose to enumerate two sphincter muscles, )f which this is the external or cutaneous ; and what they de- icribe as the internal one, is merely the circular fibres or mus- ular coat of the intestine, strengthened a little towards the knus, but not a distinct muscle. Its effect is to shut the anus. CLIV. The levator ani muscle is described as a pair of nuscles, one from each side : but it is properly one broad and in muscle, which arises from the internal surface of all the "ore part of the pelvis ; and from its breadth it has been named iusculus ani latus. It continues its origin from the internal rface of the pubis, all the way round to the sacrum. It grows radually smaller as it goes downwards to surround the anus. >o it is inserted into the circle ofthe anus, into the point ofthe s coccygis, and is mixed with the sphincter ani muscle. The vhole pelvis is lined with it like a funnel or inverted cone ; the vider part representing its origin from the pelvis, the narrower art its insertion into the anus. The whole bladder is surround- d and covered by this muscle ; the urethra passes through a plit in its fibres ; and no operation of lithotomy can reach the ladder from below without cutting through this muscle. It raises the anus, and at the same time dilates it; opening the anus for the passage of the faces, and supporting it, so as to prevent its being protruded. Thus it is not for shutting the anus, as some have supposed, but is the direct antagonist of $ the sphincter ani muscle. By enclosing the bladder, the leva- |^ tor ani acts upon it also ; for thc neck of the bladder passing 206 MUSCLES OF THE PARTS OF, &C. through a slit in its fibres, while the levator ani is acting, tli slit is drawn, as it were, round the neck of the bladder, and s the urine is for the time prevented from flowing. It is as sphincter to the bladder, which prevents our passing the urin and faces at the same moment. By surrounding the lowe part of the bladder, and enclosing the prostate gland, and thf vesicula seminales, which lie upon the back ofthe bladder, thij muscle affects these parts also ; and is perhaps the only muscl( which may be supposed to empty the vesicula, or to compres the gland, pulling upwards at the same time, so as to press th back of the penis against the pubes, to maintain the erectioi, and to assist the accelerator muscles. By enclosing the blad der, vesiculse, prostate, and anus, this muscle produces ths: sympathy among the parts which is often very distressing ; a in gonorrhoea, the stone in the bladder, constipation, piles, an i j, other diseases of these parts: for piles, constipation, or any cause f~ which may excite the action of the levator muscles, will cause erections, a desire to pass the urine, and an obstruction in tbr discharge of it. CLV. The musculus coccYGiEus is a thin, flat, muscle which arises by a narrow point from the inside of the pelvis a the spine of the os ischium: is implanted, expanded, and fleshy into the whole length of the os coccygis ; can be useful only by pulling up the point of the os coccygis, which is just equivalenI to raising the circle of the anus ; so that from every circum- stance of its form and use, it might be fairly enough described as being merely the back part of the levator ani muscle. The perinaum, where the bulb begins, is the point into whicj all the muscles .are united ; for the accelerator muscle, and th< sphincter ani muscle, touch at the beginning or point of the bulb and a small pointed slip of the sphincter ani, going upon tin bulb, connects them firmly together. The transversalis perina/J comes acrpss the perinaum from either side ; and the levatod ani muscle comes down to meet the sphincter; so that the sphincter ani, the levator ani, the transversalis perinaei, and the accelerator urinae muscles, all meet in one point, viz. the back of the bulb. They secure the perinaum, and support the heavy viscera of the abdomen: if they be unskilfully cut in per* forming lithotomy, it will be difficult to extract the stone. Ii that operation the incision passes by the side of the anus, and on the inside of the tuber ischii; and our knife accordingh cuts clean across the transverse muscles, which stand as a bai across the perinaum : it passes by the side of the erector mus- cle, need not touch it, or touches it slightly, and by a sort ot chance: it must not touch the accelerator muscle; for whoevei savs he cuts the accelerator, cuts too low, and performs his o- MUSCLES MOVING THE THIGH-BONE. 207 peration ill. After the first incision we get deep into the pelvis, and cut the levator ani. The surgeon does not observe these muscles, on account of any danger which may attend wounds of them, but takes them as marks for the true place of his inci-* sion ; and a good operator will be careful to have them fairly cut, that they may be no hinderance to the extraction of the stone.* i— Q1------- CHAP. VIII. MUSCLES OF THE THIGH, LEG, AND FOOT. MUSCLES MOVING THE THIGH-BONE. A HE muscles belonging to the thigh-bone arise all from the pelvis or trunk. The psoas magnus and iliacus internus come from within the pelvis, at its fore part, and, passing un- der the femoral ligament, go down to be implanted into the trochanter minor; and by this obliquity of their insertion, they turn the toes outwards, and bend the thigh. Other muscles come from the lower and fore part of the pelvis ; as the pec- TINALIS, TRICEPS, and OBTURATOR EXTERNUS, which arise from the arch of the pubes, and go down to be implanted into linea aspera, and lesser trochanter ; and they, pulling the thigh towards the body, are called the adductors. Others ari<^> from the sacrum and back part of the pelvis, as the OL'rr.Ei, which, coming directly forwards to be implanted into the greater trochanter, pull back the thigh ; and a fourth set com- ing also from the internal surface ofthe pelvis, viz. the obdu- rator internus, and the pyramidalis, come out through the back openings, turn round the pelvis as round a pully, and • The detrusor urinae is but thc muscular coat of the bladder ; the sphincrer vesicae, or muscle of the prostates, is but a denser fasciculus of this common coat of the bladder. 1 should no more think of describing them here than of describing the coats of the intestines or stomach. These muscles of internal parts, with the muscles ofthe internal car, &c. I reserve for those books which describe the or- gans and viscera. 208 MUSCLES MOVING THE THIGH-BONE. roll the thigh, and draw it back. This completes the catalog^ of those muscles which move the thigh. 1. The PSOAS MAGNUS, ILIACUS INTERNUS, PECTINEUS, triceps, obturator externus, which, coming from before, are inserted into the lesser trochanter, and bend the thigh. 2. The GLUTEI, GEMINI, PYRIFORMIS, OBTURATOR, INTEfi. nus, and quadratus, which come from behind, are implant- ed into the great trochanter, and extend the thigh ; and it hard- ly need be remembered, that as, when the arms being fixed, their muscles raise the weight of the body, as in climbing or in turning over a bar, by grasping with the hands ; so the mus- cles of the thigh move that thigh only which is loose and free from the weight of the body, while the muscles of the other thigh, which is fixed by the weight of the body, move not the I thigh, but the trunk upon the thigh ; so that our walking is per-* formed not so much by the muscles of the thigh moving the limb, as by their moving the pelvis, i. e. rolling the trunk upon the limb. MUSCLES MOVING THE THIGH. 1. THE THIGH IS MOVED BACKWARDS AND OUTWARDS By the Glutaus maximus,"] which is im- f Linea aspera, ------ medius, £■ planted into < Trochanter major, ------ minimus, J the (.Top of trochanter. 2. THE THIGH IS MOVED BACKWARDS, AND ROLLED UPON ITS AXIS BythePyriformis, ^J which is ("Root of the trochanter, Gemini, J implant- Obturator externus, V>ed into --------internus, j the Quadratus, J l^betwixt the trochanters. 3. THE THIGH IS MOVED FORWARDS AND INWARDS By the Psoas magnus, "*] ..... ("Trochanter minor, Iliacus Internus, ' , , . "J __—_____—— Pectinales, fP ") Linea aspera, Triceps, J L- Fascialis, I begin with this muscle, as it is necessary in the dissection. The thigh is inclosed in a very strong sheath, which, like that of the arm, sends down among the muscles strong tendinous septa or partitions ; and the muscles are in- closed in these septa ; and the great muscles of the leg are supported by it in their strong and continual actions. The MUSCLES MOVING THE THIGH-BONE. 209 tendinous fascia ofthe thigh arises chiefly from the spine ofthe ilium, partly (over the groin) from the external oblique muscle of the abdomen.. Every fascia has something added by each muscle, an£ takes a new increase and adhesion at each bone which it pasBes. It is always strengthened by adhesions to joints, and comes down from them thicker upon the muscles below; and so this fascia of the thigh, which arises chiefly from the spine of the ilium, descends, covering all the muscles of the thigh: it sends partitions down to the linea aspera and trochanters ; it has a new adhesion and a new source of tendin- ous fibres at the knee ; it adheres most remarkably at the inner side ofthe tibia, and then descends to the bran; it covers all the leg, and is again reinforced at the ankle : and this I be- lieve to be a juster history than the common idea of making it an expansion of the small tendon of the small muscle, which I am now to describe; for the fascialis is too essential to the strength of the leg to depend upon so inconsiderable an origin, and would be found there though this muscle were away, as in the palmaris of the hand. This fascia consists properly of two plates; one is that which comes down from the crest of the ilium, and from the muscles of the belly ; the other, that which arises purely from the tendon of the musculus fascialis, and which is, at the same time connected with the capsular ligament of the femur and with the trochanter; and so the muscle lies betwixt the two plates of the fascia ; and as the fascia at this part takes at least a reinforcement from the capsular ligament, and from about the trochanter major, the fascialis muscle may be said to be inserted into the trochanter. So this great tendinous fascia has these connections: the crest of the ilium ; the ligament of Paupart at the rim of the belly; the crest and arch of the pubes ; the tuber ischii, and so back along the coccyx to the ridge and processes of the sacrum ; the ligament of the joint, the great trochanter, and the linea aspera, all the way down to the knee, where its last adhesion is very strong, and from whence incomes off again much strengthened. JS* It is thicker on the outer side and back part,'and very thin on the inner side of the thigh ; and it dives with perpendicular divisions among the muscles of the thigh. CLVI. The fascialis muscle. The muscle is rightly named tensor vaginae femoris ; for hardly any othej use can be assigned. It arises from the upper spinous process of the ilium, i. e. from the fore part, or very point of its spine, by a t >. ndon of about an inch in length. It is very small at its origin mid at its termination. It is thick and fleshy in the middle. Vol. I. 2 D 210 MUSCLES MOVING THE THIGH-BONE. swelling out. It extends downwards, and obliquely back* wards, almost to the middle of the thigh ; and there it ter- minates obliquely, betwixt the two lamellae of the membrane to which it belongs. Its use is chiefly to make the fascia tense, to prepare the muscles for strong action ; and perhaps, by its adhesions about the trochanter, it may have some little effect in rolling the thigh, so as to turn the toes inwards, and oppose the Gemini. CLVII. Psoas magnus.—This and the following muscle come from within the body to move the thigh forwards. This is a very long and fleshy muscle ; of considerable strength ; of constant use ; perpetually employed in moving the thigh for- wards, or in supporting the pelvis upon the thigh-bone, so as to preserve the equilibrium of the body. It is named from psoa lumbus ; is a large round muscle, very strong, of great length, filling up all the space upon either side of the spine, and bounding the pelvis at its side. It comes froni under the ligamentum arcuatum of the diaphragm ; for it arises first by its uppermost head from the last vertebra of the back, then successively from each of the vertebra of the loins. It sticks close to the lumbar vertebra; for it arises, not only from the transverse processes, but from the sides of the bodies. These heads do not appear; for they are covered by the body of the muscle, which goes down thick and round till it reaches the sacro-iliac symphisis, and then, being united to the internal iliac muscle, they descend through Paupart's ligament. CLVIII. The psoas parvus does not, like this, belong to the thigh, but is a muscle of the loins which arises along with this one from the last vertebra of the back and the first of the loins. It is a small and delicate muscle ; ends in a slender tendon, which goes down by the inner side of the great psoas, but does not go out of the pelvis along with it: it stops short, and is implanted into the brim of the pelvis, into the os ilium, near the place of the acetabulum : it bends the spine upon the pelvis. This muscle is more regular in the monkey : in the dog it is seldom wanting. It is said to be more frequently found in women than in men: in both it often is not to be found; but sometimes in strong and big men three psoas mus- cles have been found. CLIX. The iliacus internus is a thick, veiy fleshy, and fan-like muscle, which occupies the whole concavity of the os ilium. Its origin is from the internal lip of the crista ilii: it adheres to all the concave surface of that bone down to the brim of the pelvis ; to the fore part ofthe bone under the spinous process ; MUSCLES MOVING THE THIGH-BONE. 211 and to a part also of the capsular ligament ofthe joint: all its radiated fibres are gathered together into a tendon at the liga- ment of Paupart. This tendon is longer on the lower than on the upper surface : for below it slides on the pubes as upon a pulley, and continues tendinous, that it may bear the friction ; but above it is unconnected, or it is connected only by loose cellular substance; and there it is quite fleshy. Just under the ligament the two tendons are joined ; whence they bend ob- liquely round to be implanted into the lesser trochanter. The psoas magnus and iliacus internus are two very power- ful muscles. Their chief use is to bend the thigh, and more peculiarly of the lumbar one to support the body. The great blood-vessels come down along with these two muscles : the muscles and vessels are both surrounded with loose cellular substance. Matter often forming behind the abdomen, round the psoas muscle, is named the psoas abscess ; and penetrating under Paupart's ligament, bursts in the thigh at last, and is commonly fatal. CLX. The pectineus, or pectinalis, is so named from its arising at the pecten or pubes ; is a broad flat square mus- cle ; lies along side of the last described muscles ; and is in- serted with their common tendon. It arises flat and fleshy from that line ofthe pubes which forms the brim of the pelvis, and is implanted into the linea aspera by a tendon flat and long, pretty nearly of the same extent and shape with its origin. This muscle lies immediately under the skin and fascia lata; and by its bending round under the thigh-bone it has three actions: to close the knees together ; to pull the thigh forward; to perform rotation, turning out the toe; and in certain positions ofthe limb it will pull the thigh back, assisting the extensor muscles. CLXI. The triceps femoris is a broad flat muscle, with three heads, arising from the pubes, and inserted into the whole length of the linea aspera down to the condyle, and serving for pressing the knees together or bringing the thigh forwards. The triceps consists of three heads, which lie in different layers, one above the other ; and have so little connection :imong themselves, that they have been more commonly, and I think properly, described as ihree muscles. These three parts ofthe muscle are indeed for one common use : but they are ot \ ery different fonns; for they do not even lie on the same plane : one is long : another shorter by one half; a third long- er than both the other two; so that they have been commonly described under the names of adductor primes or i ongus ; 212 MUSCLES MOVING THE THIGH-BONE. ADDUCTOR SECUNDUS Or BREVIS ; ADDUCTOR TERTIUS Or MAGNUS. 1. The adductor longus is the uppermost layer ; its bor- der (for it, like the pectinalis, is a flat muscle) ranges with the border ofthe pectinalis. It arises from the upper and fore part of the pubes by a short roundish tendon, very strong: it swells into a thick fleshy belly, not round, but flattened; the belly grows flatter as it goes down towards the thigh-bone ; it ends in a flat and short tendon, which is inserted web-like into the linea aspera in all its middle part, viz. about four inches. Thus the muscle is of a triangular form, with its base in the linea as- pera, and its apex on the pubes. Its head or origin lies betwixt the pectinalis and the gracilis : its upper edge ranges with the pectinalis ; its lower edge lies upon the triceps magnus. It is called longus, because it is longer than the next head. 2. The adductor brevis lies under the adductor longus, and is of another layer of muscles ; for as the first layer con- sists ofthe pectinalis, triceps longus, and gracilis, this layer con- sists ofthe obturator externus, triceps, brevis, and triceps longus. The triceps brevis is exceedingly like the former, in rising near the symphisis pubis, by a thick and flattened tendon, swelling like it into a strong fleshy belly ; like it, it grows flat, and is inserted by a short flat tendon into the inner trochanter and linea aspera. But it differs in these points : that it is less oblique; for this muscle being shorter, goes more direcuy across betwixt the pelvis and the thigh : that it is placed high- er than the last; so that whereas the adductor longus is insert- ed into the middle of the thigh bone, this one is inserted into the lesser trochanter, and only the upper part of the linea aspe- ra ; and the triceps longus is a superficial muscle, while this is hidden under it and behind it. The longus takes its rise from the very crest of the pubes ; this takes its origin from the fore part of the pubes, from the limb just under the crest, so as to be immediately under the head ofthe longus. 3. The adductor magnus, the third head ofthe triceps, is a very long and flat muscle, lying behind the other heads. It arises by a short tendon, just under the tendon of the adductor brevis : it continues to have a fleshy origin all down the ramus and the tuber ischii (i. e.) from the flat edge of the thyroid hole. From this broad origin it goes to be implanted into the thigh-bone the whole length of the linea aspera, its fibres hav- ing various degrees of obliquity according to their insertion; for the uppermost fasciculi go almost directly across, to be in- serted flat into the upper part ofthe linea aspera ; the succeed- ing fasciculi go more and more obliquely as they descend, the lower part of the muscle following that rough line which leads MUSCLES MOVING THE THIGH-BONE. 213 to the condyle; and the last fibres of all are implanted by a ten- don of considerable length into the condyle itself. This adduc- tor magnus makes, as it were, a flat partition betwixt the fore and back parts of the thigh; and it is about three inches above the condyle that the great artery passes betwixt this tendon and the bone, perforating the triceps, to get from the fore to the back part ofthe thigh, and down into the ham. The use of all these muscles is entirely the same, making allowance for their various degrees of oblique insertion ; and they must be very powerful, by the great distance of their ori- gins from the centre of that bone which they move : so that while other muscles pull in a direction very oblique, these three heads of the triceps must pull almost at right angles, the most favourable direction of all. CLXII. The obturator externus is named after the ob- turator ligament, from which it arises. The ligament and the muscles shutting up the foramen thyroideum are named ob- turators ; and it is sometimes named rotator femoris extrorsum, from its turning the thigh outwards. It arises from the ramus of the ischium and pubes where they form the margins of the thyroid hole ; and from the outer surface of the ligament, which it occupies entirely, leaving only room for the obturator vessels and nerves. It is a short muscle ; its origin is broad, and its insertion narrow, so that it is of a conical form; for the flesh of this muscle is gathered very soon into a round short tendon, which twist under the thigh-bone betwixt it and the pelvis : so that it is in a manner rolled round the thigh- bone, being inserted into the root of the great trochanter. It pulls the thigh forwards, but is more peculiarly a rotator of the thigh. This muscle is ofthe second layer; and the succession of all the muscles is this : the upper layer consists of the psoas and iliacus, where they come out from the abdomen ; of the pectinalis ; and of the long head of the triceps : ti|e second layer consists of the short head of the triceps : and the third layer consists of the obturator externus at the upper part, and of the triceps magnus, or third head of the triceps, all down to the condyle. Glutei.—There are three glutai muscles, each under the other, and each smaller than the muscle which covers it. The first, arising from the back part ofthe ilium, the back ofthe sacrum, and the sacro-sciatic ligament, forms the whole hip, and descends so low as to be inserted into one third of the length of the linea aspera, and into the root of the great tro- chanter. The second arises from all that portion of the ilium which 214 MUSCLES MOVING THE THIGH-BONE. is before this one, and from the back of the bone, and goes down to be inserted into the very top of the great trochanter. The third arises from the back of the bone below the last, down to the acetabulum and sacro-sciatic sinus; and it is in- serted into the root betwixt the apex ofthe great trochanter and the neck ofthe bone. CLXIII. The gluteus maximus arises from the back of the ilium one half its length; from the joining of the ilium and sacrum ; from all the spines and irregularities of the sacrum; and from the sacro-sciatic ligament. Its thick fleshy fascicuke come in a winding and oblique direction down to the thigh- bone ; and, being gathered into a flat and pretty broad tendon, it is inserted into the root of the trochanter major, and down three inches of the linea aspera. This is one of the largest and most fleshy muscles of the body; covers all the other muscles ofthe hip ; forms the contour of the hip ; pulls the thigh back- wards, or the body forwards upon the thigh when the thigh is fixed : and being a wide spreading muscle, which in a manner surrounds its joint, its different portions act with different effects ; not only according to their natural direction, but ac- cording to the accidental positions of the pelvis with regard to the thigh-bone. CLXIV. The gluteus medius or minor is smaller than the former, but like it. It arises from all the outside of the ilium not occupied by the glutaus major. It, like the other, is a fan-formed muscle; for its fibres converge from its broad origin in all the back of the ilium, to form a short flat tendon, . which is inserted into the back or into the very top ofthe great trochanter. It lies in part under the glutaus maximus ; but its chief part lies before the glutaus maximus : and as certain portions of the muscle are before the thigh-bone, there are po- sitions of the pelvis and thigh-bone in which it will pull the thigh foi«prards, although its proper office is to assist the glutaus magnus in pulling the thigh backwards, and moving it out- wards from the body. CLXV. The gluteus minimus is a small radiated muscle, which lies deep, and quite under the former. It has, compared with the former, a very narrow origin; for it arises chiefly from the lowest part of the back of the ilium, viz. that part which forms the socket for the thigh-bone, and a little higher up ; and from the border of the sciatic notch. It forms a short, flat, and strong tendon, which is fixed under the root of the trochanter major, betwixt the trochanter and the neck of the bone : so that these muscles are inserted in this succession ; first, the great glutaus, below the root of the trochanter, and MUSCLES MOVING THE THIGH-BONE. 215 into the linea aspera ; the middle glutaus into the back and top of the trochanter; and the smallest of the glutaei is implanted into the roughness under the root of the trochanter. Gemini.—The gemini are two muscles, or rather one biceps muscle ; but the heads are so distinct that they are reckoned two, and so much alike that they are named gemini. CLXVI. The uppermost, the larger and stronger muscle, arises from the spinous process ofthe os ischium. CLXVI I. The second, or smaller head, arises in like man- ner from the tuber ischii, upon its ball or outer end. They are fleshy in their whole length. They meet and unite their ten- dons at the great trochanter. They are inserted firmly, along with the following tendon, at the root of that process. CLXVIII. The pyriformis, sometimes called iliacus in- ternus or pyramidalis, comes from the hollow of the sacrum, runs in the same line with the lesser glutseus, and is inserted with the two last named muscles in the root of the great tro- chanter. Its origin is from the hollow of the sacrum, rising from the vertebra of-that bone by three or four small fleshy digits, and from the sacro-sciatic notch ; it runs betwixt the glutaus mi- nor and the gemini, and its round tendon is inserted betwixt them, somewhat connected with each. The pyriformis, gemini, obturator internus, and quadratus, form what some anatomists have called musculi ojjadr age- mini ; and they are so much alike in insertion and use, that it would be waste of time to repeat what has been said of the gemini and obturator. This muscle, the pyriformis, like the others, rolls the thigh outwards. Its name is from its shape. CLXIX. The obturator internus, once named marsu- pialis or bursalis, arises from all the internal surface ofthe obturator ligament, and from all the edges ofthe thyroid hole, from the ilium, ischium, and pubes : so it arises within the pel- vis ; comes out by turning round the ischium in the notch be- twixt its tuber and its spine. Its origin is therefore circular and fleshy. It rims along the inside ofthe os ischium, turns round that bone betwixt the spinous process and the tuber. The hol- low there is guarded with cartilage; and this tendon runs in the hollow, like a pully round a rope ; passing this, it runs betwixt the two legs of the gemini, and its tendon is united to theirs ; and the three, appearing almost like one tendon, are inserted together into the root of the trochanter major. These, then, might with some propriety be named one muscle: all the three, viz. die two gemini muscles and the obturator muscle, passing between them, were once accounted as one muscle, and then it 216 muscles moving the THIGH-BONE. seemed to be a muscle with two bellies and an intermediate tendon; and this intermediate tendon, with two fleshy ends, give it the appearance of a purse, and thence it was named musculus marsupialis, or bursalis. CLXX. The ojjadratus femoris, is a thin flat muscle, passing in a transverse direction betwixt the tuber ischii and the thigh-bone. It arises from the lower and flattened surface of the tuber ischii by a short tendinous beginning. It goes a little oblique- ly upwards and outwards, and is inserted into the back of the great trochanter, in that roughness which is found just where the trochanter is joined to the bone, and goes obliquely betwixt the trochanter major arid the trochanter minor. It rolls the thigh-bone, so as to turn the toe outwards, and pulls it almost directly backwards. The motions of the thigh must be performed by many very strong muscles, as it moves under the weight of the whole body; and it seems to be curiously contrived, that the muscles fit for moving the thigh forward should, in certain positions of the thigh, move it backwards ; also giving an increase of strength to that motion of the thigh in which most strength is required. There are but two, or chiefly two, points for insertion; the trochanter major and the trochanter minor. These two points are sd"oblique, that no one muscle, nor set of muscles, performs any direct motions ; for they all twist round the bone's axis, to get at their insertion. The glutai, the pyriformis, the gemini, the quadratus, the obturator internus, and obturator externus, all bend round the axis of the thigh-bone, to reach the tro- chanter major. These now may be called the abductors of the thigh, to pull it outwards ; but we should conclude from this direction, that they could not pull the thigh backwards, for the thigh-bone would turn on its axis and elude their action.— The psoas magnus, the iliacus internus, the pectinalis, and the triceps, do in the same manner go round the inner side of the bone : the two first to be implanted into the trochanter minor, the two latter into the linea aspera, just below it. These are justly named adductors ofthe thigh : their chief use is to draw the thighs together : and this is the combined effect of these two sets of muscles. When the adductors act by themselves, they pull the thigh forwards, moving the leg, rolling the thigh- bone, and turning the toe out in a graceful step ; which is most peculiarly the effect of the pectinalis and triceps. But when we are to finish the motion, by pulling forward the body, which is the same with pulling back the thigh, it is not merely the muscles moving the thigh-bone. 217 antagonists of these muscles, as the glutai, the gemini, &C. which must act. Were the glutai to act alone, they would rather turn the thigh upon its axis outwards than pull it back; but the triceps, ckc. act again in conjunction with the glutai, he. and by the action of the triceps, the inner trochanter is fixed ; the further rolling of the thigh is prevented ; the full effect is given to the glutai muscles. When the glutai act, they pull the thigh directly backwards, assisted by the triceps, pectinalis, and others: for now the thigh-bone is so far advanced before the body, that those muscles, as the triceps, which were benders ofthe thigh in its first position, are exten- sors when it is advanced a step before the body ; or, perhaps, it will be more explicit to say, that when the thigh is moved one step before the body, the iliacus internus, psoas magnus, and triceps muscles, co-operate, agree with the glutai muscles in bringing the trunk forwards to follow the limb, and then in fixing and stiffening the trunk upon that limb, till the other thigh is advanced a second step before the body. The muscles of the leg are the most simple of all: for the knee is a mere hinge, at least it is so in all our ordinary mo- tions ; so that there is no action to be performed but those of mere flexion and extension ; and there are only two classes of muscles to be described, the extensors and the flexors of the leg. 1. The extensors of the leg. The only muscles.which extend the leg are those four, which may be very fairly reckon- ed a quadriceps extensor cruris. Indeed the French anato- mists arrange them so. Sabbatier calls them the triceps fe- moris. These muscles, which all converge to the patella, and are inserted in it, are : Rectus Femoris, Vastus Externus, Cruraeus vel Femorseus, Vastus Internus. And these are all implanted by one tendon; because the joint being a hinge, bending only in one direction, its muscles could have given but one motion, however oblique their origin and course had been. 2. The flexors of the leg are one on the outside and four on the inside of the leg; the tendons of the outside being im- planted into the upper knob of the fibula, and those in the in- side into the rough head of the tibia, forming the hamstrings, and extending their tendons or aponeurotic expansion down- wards upon the leg. inside flexors. Sartorius, Gracilis, Semitendmosus, Semimembranosus. Vol. I. 2 E 218 muscles moving the leg. outside flexor. Biceps. flexor lying in the ham. Musculus Poplitaus. extensors of the leg. CLXXI. The rectus femoris, sometimes rectus cru- ris, is so named from its direction ; it is a thin flat muscle, and arises by two heads. The first or greater head arises from the lower spinous process of the ilium by a short round tendon ; its second head is in a different and in somewhat of a curved direction ; for it comes from the head of the acetabu- lum and from the capsular ligament. These join together, and form a flat tendon of four inches in length, which becomes gradually fleshy and larger down to its middle, and then again contracts towards the patella in the same gradual manner. There is a middle tendinous line running the whole length of the muscle, especially conspicuous on its back part; and to- wards that central line all the muscular fibres converge. The rectus is united at the sides to the vasti; at the back part to the Cruraus ; and its tendon, along with that of the cruraus,- goes to be directly implanted into the rotula of the knee. The rectus cruris is the first of those muscles which Sabba- tier calls the triceps femoris ; and surely they may be as properly named thus as the triceps cubiti extensor. This large mass of muse e or flesh enwraps the whole ofthe thigh-bone behind as well as before : for, first, the cruraus arises fleshy from all the fore part of the bone ; the vastus externus from the great trochanter, and all the back part and outer side of the bone ; and the vastus internus arises, in like manner, from the lesser trochanter, and all the inner side of the bone, from the trochanter major all round to the origin of the cruraus. CLXXII. The cruraus arises from the fore part of the trochanter minor ; and it continues its origin from the fore part of the femur, the whole way down to within two inches or little more of the patella. About three inches from its origin it is joined by the vastus externus, which unites with it at the outer edge and fore part; and the vastus internus comes into it about five inches below its origin, and joins it at the inner edge and fore part. At its lower part it is joined to muscles moving the leg. 219 the tendon of the rectus, to form but one large tendon, which is inserted into the rotula. Under the cruraus are sometimes found two little muscles, or rather two little slips of this muscle, which are quite dis- tinct. They arise on the fore part of the thigh-bone, two or three inches above the capsule of the joint; and they are in- serted into the capsule on each side ofthe patella, evidently for the purpose of pulling it up, to prevent its being catched ; and when these two (subcrur^i) are not found as distinct mus- cles, some fibres ofthe cruraus supply their place. CLXXIII. The vastus externus is the largest of these three muscles. Its origin is by a pretty thick and strong tendon from the lower and fore part ofthe trochanter major ; and it continues its origin from the root of the trochanter all down the linea as- pera to that rough line which goes to the inner tuberosity of the thigh-bone. It touches the end ofthe cruraus about four inches below its origin, and continues attached to it the whole way down ; and then it forms a flat tendon which connects itself with the ten- don of the rectus femoris, and then embraces in a semicir- cular manner the outside of the patella. And several of the fibres of this aponeurosis not only cross over the rotula, but go down over its opposite side to glide along the head of the tibia, and to be inserted into the inner side of the knee. CLXXIV. The vastus internus is neither so large nor so fleshy as the vastus externus ; but it is exceedingly like it in all other respects. It arises from the fore part ofthe trochanter minor just un- der the insertion of the psoas magnus ; and it continues its origin from the linea aspera the whole way down to the inner condyle, exactly opposite to the origin of the vastus externus, so that their origins meet; they leave just a channel betwixt them. The vastus internus, very soon after its origin, joins itself to the cruraus, or middle portion, and accompanies it in all its length : and at the distance of two inches from the rotula it unites itself with the tendon of the cruraus at its internal edge ; and this tendon completes that junction which unites the four muscles into a quadriceps cruris. This vastus inter- nus descends much lower, in a fleshyr form, than the external vastus does ; and forms that fleshy cushion which covers the inner side of the knee joint. Its tendon embraces the rotula somewhat in the same circular form with that of the vastus ex- ternus ; and, like the externus, it sends some fibres across the knee-pan, to be inserted in the outer part of the head of the tibia. 220 MUSCLES MOVING THE LEG. The rectus, and the vastus externus, internus, and cruraus, form one large mass of flesh, which embraces and incloses all the thigh-bone ; and they are so connected, that the cruraus cannot be separated, and cannot be neatly distin- guished. The use of these four muscles is evident to extend the leg and to. bend the thigh on the trunk, or reciprocally to bend the trunk on the thigh. This, or these two motions alternately,h the common use of these muscles, as in walking ; and they ate most peculiarly useful in running and leaping. After describing a large mass, conjoined in one tendon, and concurring in one simple action, it is superfluous to say that its power must be great. This power must be still further increas- ed by the rotula, which removes the force from the centre, and gives the advantage of a pulley, which it really and truly is: without this pulley these muscles could be of no use in certain situations ; for instance, in the recumbent posture: for then the extending muscles being in the same line with their bones, could have no farther power ; but the rectus, by the pulley of the rotula, and by its attachment to the basin, raises the trunk, or at least helps the psoas, the iliacus, and the muscles ofthe belly. The rotula is again attached to the tibia by a strong liga- ment, to sustain the pulling of these great muscles.* flexors of the leg. CLXXV. The sartorius orTAVLOR's muscle, is so nam- ed from its bending the knees and drawing the legs across. It is the longest muscle, and a very beautiful one: it extends obliquely across the whole length of the thigh, crossing it like a fillet or garter, about two inches in breadth. It arises from the upper spinous process of the os ilium, by a tendon about half an inch in length; its thin flat belly extends obliquely across the thigh, like a strap, and is inserted in the * These muscles are in continual action : for their office is to resist the bending of the knee, which would happen by this incumbent weight of the body; so that the continual support of the body depends wholly on these muscles; and they are the great agents in running, leaping, walking, &c. Since, by extending the knee, they raise the weight of the pelvis and trunk, and of all the body, they must be very powerful; and accordingly when they are weighed against their antagonist mu- cle, we find them greatly to exceed ; for the ojjadriceps, i. e. the rectus, cruraeus, and vasti, will weigh four pounds, while the biceps, &c. their antagonists, weigh but two pounds. This experiment was often repeated by the great Cowper for Mr. Brown, who was delivering lectures on muscular motion. MUSCLES MOVING THE LEG. 221 same oblique form into the inner tubercle of the head of" the tibia; its aponeurosis spreads pretty widely, going over the Whole joint of the knee a thin sheet of tendon. From the oblique position of the muscle, it might in action change its place ; but it is closely embraced by the fascia lata, and is tied by such adhesions as form something like a pecu- liar sheath of itself. It turns the thigh like the quadrigemini and obturator mus- cles. It also bends the leg upon the knee ; and when the leg does not yield, it bends the thigh upon the pubes ; or where the thigh also is fixed, it bends the body forwards : but in perform- ing that action, whence it has its name, it does all these ; for first the leg and thigh are rolled, then the thigh is bended to- wards the belly, then the legs are bent to draw them across. Though a small muscle, yet it is of great power from its origin, and in some degree from its insertion also ; being much re- moved from the centre of motion. CLXXVI. The gracilis, sometimes called rectus in- ternus femoris,* is a small, flat, thin muscle, in its general shape somewhat like the sartorius. It arises by a flat tendon of two inches in length from the pu- bes and near the symphysis ; and it passes immediately under the integuments down to the knee : it passes bv the inner con- dyle of the knee, in the form of a short round tendon ; and as it bends behind the head ofthe tibia, it is bound down by a bun- dle of tendinous fibres, which crossing it, go to the back part of the leg. After passing the head ofthe tibia, it turns oblique- ly forwards and downwards ; it here runs behind the tendon of the sartorius, and before that of the semitendinosus. It is in- serted with the sartorius into the side of the tuberosity at the top of the tibia. This muscle runs also in a line so wide from the centre of motion, that its power is very great. It serves chiefly as a flexor of the leg : when the leg is fixed, it must, by its origin from the pubes, be a flexor of the thigh, and an adductor in nearly the same direction with the pectineus and triceps ; and it is worth observing, that while the knee is straight, the sarto- rius and the gracilis cannot bend the knee : they, on the con- trary, keep it steady and firm : but when the knee is bent, they come into action ; for in proportion as the muscles which have made the flexion are contracted, they are less able to contract * Gracilis is from its smallncss; rectus internus is from its straight di- rection. 222 MUSCLES MOVING THE LEC. farther; and therefore it is desirable that more muscles should come into play. CLXXVII. The semitendinosus is so named from its lower half being composed of a small round tendon ; and as tendon was once misnamed nerve, this is the seminervosus of Winslow, Douglas, and others. Its origin is from the tuberosity of the ischium (along with the semimembranosus, and touching the biceps) by a short thick tendon. It also arises by many oblique fasciculi of fibres from the posterior portion of its opposite muscle the biceps cru- ris. This cross connection betwixt the two muscles continues for three inches down from the tuber ischii ; it then departs from the biceps, goes obliquely inwards, and is flattened and contracted into a tendon six inches from the knee. lis tendon then becoming smaller and rounder, passes down behind the inner tubercle of the knee ; and getting round the head of the tibia, it comes forward to be inserted into the tuber at the head of that bone. At this place the tendon grows broad and flat; it is expanded, and as it were grasps the inner side ofthe knee; its upper edge is joined to the lower edge of the tendon of the gracilis, so that the sartorius, gracilis, and semitendinosus, are implanted like one muscle ; and this tendinous expansion seems like a capsule for enclosing the heads of the tibia and femur, and for strengthening the knee-joint. The semitendinosm bends the leg. CLXX VIII. The semimembranosus has its name from the muscle, which is flat, thick, and fleshy, beginning and ending with a flattened tendon, somewhat like a membrane, but infi- nitely thicker and massier than such a name should imply. It arises from the tuber ischii, before the semitendinosus and biceps. It arises a broad, thin, and flat tendon, of about three inches in length. It becomes fleshy and thick in its middle, but it soon becomes thinner again, and terminates in a short tendon, which gliding behind the head of the tibia, is inserted there.* This muscle has little connection with any other. It lies un- der, or, more properly speaking, on the inside ofthe semiten- dinosus, and the two together form the hamstrings. The ham- string muscles contribute also to another motion. Though, * The two tendons of this muscle, the membranous tendon at the head, and this smaller one by which it is inserted, stand so obliquely, that the muscular fibres betwixt them must be very oblique; for the membranous tendon descends low upon the back part or edge, and the tendon of insurtion begins high upon the fore edge of the muscle. MUSCLES MOVING THE LEG. 223 when extended, the tibia cannot roll, yret when we sit with our knees bent, it can roll slightly ; and such rolling is accomplish- ed by these muscles. All these muscles which bend the leg, and which consequently extend the thigh at the same time, are muscles of very great power ; because they arise in one com- mon point, the tuber ischii, and that point is very far distant from the centre of motion. There is still one small muscle, a flexor ofthe leg, which per- forms this rotation during the bent state of the knee with most particular power. CLXXIX. The musculus poplit^us, which is so named from its lying in the ham, is a small triangular muscle, lying across the back part of the knee-joint, very deep under the ham- strings, and under the muscles of the leg. Its origin is from the outer condyle of the thigh-bone, and from the back part of the capsule of the joint. Its tendon is short and thick, but of no great extent. It passes fleshy behind the knee-joint; and it is inserted broad into a ridge on the back part of the tibia ; so that by its small origin and broad insertion it is a fan-like muscle ; its fibres being almost transverse, and its lower fibres nearly perpendicular. Besides bending the leg, it is useful by pulling aside the capsule to prevent its being catched. CLXXX. The biceps cruris, so named from having two heads, a long and short one, lies immediately under the skin, in the back part of the leg, running down from the pelvis to the knee, to form the outer hamstring. It is the single flexor on the outside of the thigh. Its origin is from the outer part of the tuber ischii by a tendon of an inch and a half in length. And this tendon is, in its origin, closely united with that ofthe semitendinosus for two inches, or at least the whole length of the tendon. After a short, but very thick fleshy belly, it degenerates into a tendon, especially on its back part; and this tendon, which begins above the middle of the thigh, is continued the whole way down. About one third down the bone is the beginning ofthe second or short head, which has its origin all the way down the linea aspera to the line above the outer condyle of the thigh-bone ; and here it is somewhat connected with the origin ofthe vastus externus muscle and the insertion of the glutaus magnus. The tendons of the two heads are joined a little above the inner condyle, and go outwards to be inserted into the outer part of the head of the fibula, forming the outer hamstring. Its insertion surrounds the head of the fibula, and a small portion also sinks betwixt the bump of the fibula and the inner head ofthe tibia, to be implanted into it also. 224 MUSCLES MOVING THE LEG. This muscle, like the opposite ones, serves for bending the leg. The short head simply bends the leg ; the long head assists the short one in bending the leg, and is also a muscle of the thigh. The muscles of the foot are six extensors and one flexor MUSCLE. EXTENSORS. Gastrocnemius vel gemellus, ""* Gastrocnemius internus vel soleus, 1 Tibialis posticus, i all lying on the back Peroneus longus, j part of the leg. ---------brevis, { Plantaris, J The Flexor is, The tibialis anticus, lying on the fore part of the leg. CLXXXI. The gastrocnemius is often divided into three muscles, named gastrocnemii or gemelli. But, far from counting thus, we should rather favour the arrangement of Douglas, who couples this with the next muscle, as forming a quadriceps or two muscles joined with two heads each, and he calls it the extensor cruralis. The gastrocnemius is the great muscle of the brawn: its two heads are two veryr large and fleshy bellies, which arise from the tubercles of the thigh-bone. The inner head is the larger, and arises by a strong tendon from the back of the in- ner condyle, and a little way up the rough line; and it has also a strong adhesion to the capsular ligament of the knee. The outer head is shorter than this : it arises in the same way, from the outer tubercle of the thigh-bone ; and the two muscles meet and run down together, forming the appearance of a rapha, by the direction of their fibres. But the two bel- lies continue distinct till they meet in the middle of the leg. They are distinct at their back part, but at their fore part they are connected by a tendinous aponeurosis, or strong but flat tendon ; and the two bellies being about the middle of the leg united firmly, they form a large flat tendon, very broad at its beginning, which unites with that of the soleus a litde above the ankle. CLXXXII. Soleus.—This name is from its resemblance to the sole-fish ; and it is often named gastrocnemius inter- MUSCLES MOVING THE LEG. 225 nus. This, like the last muscle, has two heads, which arise from either bone. One head arises from the bulb of the fibula, and continues to adhere to one fourth of the upper part of the bone ; another head arises from about three inches of the upper part of the tibia. The first of these heads is large and round; the second is smaller and round; they unite immediately; and a large fleshy belly is formed, with still a conspicuous division betwixt the flesh of the two heads. The great tendon begins about half way down the leg, but still is intermixed with fleshy fibres till it approaches the heel. A little below the middle of the leg this tendon is united with the tendon of the gastrocne- mius, to form the great back tendon, named tendo Achillis, and sometimes, though very rarely, chorda magna. The tendon is large ; it grows small as it approaches the heel ; when it touches the extremity of the heel bone, it ex- pands to take a firmer hold. In running, walking, leaping, &c. this muscle, with the ex- tensors of the leg, are the great muscles. The external gastrocnemius has double power; for it, arising from the tubercles ofthe thigh-bone, is both an extensor of the foot and a flexor of the leg ; but the gastrocnemius internus is a mere extensor of the foot, and both together have such strength as often to break the tendo Achillis. CLXXXIII. Plantaris.—This muscle is named from a mistaken notion of its going to the planta pedis or sole of the foot, to form the plantar aponeurosis, like the palmaris of the hand ; but, in fact, it does not go to the sole, but is a mere ex- tensor of the foot, inserted along with the tendo Achillis. This long and slender muscle is situated under the gastroc- nemius internus. It arises from the external condyle of the femur wholly fleslry ; it also has an attachment to the capsular ligament of the joint ; after an oblique fleshy belly of about three inches, it forms its small flat tendon. The tendon runs betwixt the inner head of the gastrocnemius and the soleus ; and where the tendo Achillis begins, the tendon of the plan- taris attaches itself to the inner edge and fore part of the Achillis tendon ; it accompanies it down to the heel, running in a groove which seems made to receive it; and is im- planted with the tendo Achillis into the inner side of the heel- bone. It is often wanting. The use of this muscle is to tuck up the capsule in the great bendings of the knee-joint, and to assist the gastrocnemii muscles. The PERONiti muscles are those which arise from the fibula. They are named from their length being different: the pero- Vol. I. 2 V 226 MUSCLES MOVING THE LEG. n,eus longus being as long again as the brevis ; for it is one half longer in its origin, the one rising at the head, the other at the middle of the bone ; and again it is one half longer at its insertion, going fully round under the foot ofthe opposite side, while the shorter peronaus stops at the side of the foot to be inserted. CLXXXIV. The peronaus longus is so named from its lying along the fibula. It arises partly tendinous, chiefly fleshy, from the upper knob of the fibula, and from the ridge of the bone, down to within three inches of the ankle. It has another small slip of a head from the upper part of the tibia, above where the fibula joins ; it has also adhesions to the tendinous partition, which separates this from the extensor digitorum communis and the soleus. Its tendon begins very high above the middle of the leg; and it continues to receive the fleshy fibres almost at right angles in the penniform manner. The tendon is concealed down to about or below the middle of the leg: then it is seen immediately under the integuments; and we can easily distinguish it through the skin, being that acute line or string which runs down behind the inner ankle, and which gives shape to that part. In passing the outer ankle, it runs down through a cartila- ginous pulley or annular ligament, which also transmits the pe- ronaus brevis: it leaves the peronaus brevis on the side of the foot; and passing by itself in a groove of the heel-bone, it bends obliquely across die arch of the foot, goes quite down to the opposite side, and is inserted into the metatarsal bone ofthe great toe, and the great cuneiform bone on which it is founded. Under the eminence of the os cuboides it suffers great fric- tion, so as to be thickened to a degree of ossification, and to re- semble a sesamoid bone. It is also thickened in a lesser de- gree as it passes the outer ankle ; and in all this length it is tied down by a strong ligamentous expansion. It is a powerful extensor of the leg ; it also gives that obli- quity of the foot, which is so handsome and natural, and useful in walking. This muscle particularly turns down to the ground the inner edge of the foot; so it presses to the ground the ball ofthe great toe ; and that is the part which touches the ground, and which feels sore after long walking or violent leaping or running : it is by that part that we push in making a step; so that this muscle is perceived to be continually active in all mo- tions of walking, leaping, running, and more particularly in dancing. CLXXXV. The peronaus brevis is like its fellow except in length and insertion. Its origin is from the ridge ofthe fibu- muscles moving the leg. 227 la; beginning about one third down the bone, and continuing its adhesion the whole way to the ankle. It also has adhesions to the tendinous partition which is betwixt it and the common extensor; so that these two muscles are by such adhesions very difficult to dissect. It is smaller at its origin, but increases in its fleshy belly as it descends ; and it is fleshy lower down than the peronaus longus. It is like it, a penniform muscle.— The tendons of the two peronai pass together by the outer an- kle in the same ring: but the tendons cross each other ; for the peronaus longus is in its belly more forward. The brevis lies under, and behind it, quite covered by it; and yet the tendon ofthe brevis, by creeping under the longus, gets before it, just under the outer ankle ; and from that it runs in a separate groove, superficially, upon the outer edge of the foot, to be in- serted into the metatarsal bone ofthe little toe. In both mus- cles the tendon is upon the outer edge, and begins almost as high as the upper head of each muscle. This tendon of the peronaus brevis is the shorter one, is small where it passes through the pulley, and expands when it reaches its insertion, that it may grasp the metatarsal bone firmly. The tendon of the longer muscle also expands a little, and somewhat in the form of a hand and fingers, taking hold of two bones by three little heads. This muscle assists the former in extending the foot and co- incides well in its oblique action with the last; for as the last turned down the inner edge of the foot, this turns the outer edge upwards, which is exactly the same motion. CLXXXVI. The tibialis posticus is a penniform mus- cle, very much like the two last described, only its tendon goes round the cartilaginous pulley of the inner ankle. It is named tibialis from its origin, and posticus from its place. It arises from the back part and ridge of the tibia, from the opposite part ofthe fibula, and from the interosseous membrane below these ; and it continues its attachment to the interosseous ligament quite down to the ankle. It has also strong attach- ments to the surrounding tendinous partitions. Its fibres are all oblique, and go to the middle tendon, which is in the heart of the muscle. About the middle of the tibia this tendon be- gins to emerge from the fleshy belly ; it grows gradually small- er, but still continues to receive flesh quite down to the ankle. It passes in the groove of the inner ankle, and is retained there by such a ligament as holds the peronaei. After passing the li- gament, it expands in the hand-like form, to grasp the bones of the tarsus : and it is expanded much more than the peronaus ; for it sends roots down among the bones both ofthe tarsus and 228 muscles moving the toes. metatarsus, so as to take hold first on the lower rough part of the naviculare in passing over it. Then it is implanted into the two first metatarsal bones, then into the calcaneum, and lasdy into the os cuboides ; and where it passes over the os na- viculare it is hardened into a sort of sesamoid bone. In short, it is implanted in the sole of the foot by a tendon like a hand, which sends down its fingers among the tarsal and metatarsal bones, to take the surest hold. This muscle pulls the foot in so as to put the toes together ; and when balanced by the peronsei, it directly bends the foot. CLXXXVII. The tibialis anticus crosses obliquely the fore part of the leg. It arises from the fore part and out- side of the tibia. It beginsjust under the outer tuber, and con- tinues its adhesion down two thirds of the bone; then the tendon begins to be formed: and this muscle, like almost all the smaller ones ofthe leg, adheres to the tendinous partitions, and to the fascia, with which they are covered. The tendon begins almost with the origin ofthe muscle ; but continues co- vered by the flesh, and not appearing till within four inches or so ofthe ankle, when it begins to pass obliquely over the leg; and having completed the crossing above the ankle, it goes under the annular ligament in a peculiar ring : it runs along the side of the foot, and is implanted into the os cuneiforme in- ternum ; and a small production of the tendon goes forward to be inserted into the metatarsal bone of the great toe. It is the only muscle which bends the foot, that is, which turns the great toe towards the leg. MUSCLES OF THE TOES. The long muscles ofthe toes are just four, two flexor and two extensor muscles. The flexor muscles lie upon the tibi- alis posticus, or behind betwixt it and the solaeus. The exten- sor muscles again lie under the tibialis anticus, or at least then- heads are under it, and their bellies only appear from under it about the middle of the leg. The flexor tendons follow the tendon of the tibialis posticus by the pulley of the inner ankle into the hollow of the foot.— The tendons of the extensor muscles keep with that of the tibi- alis anticus, and cross over the fore part or rising of the ankle, where the tibia is united with the astragalus. And in dissec- tion we must follow these in an opposite order to that in which they are described ; for next to the fore part of the solaeus is, 1st, The flexor pollicis ; 2dly, The flexor digitorum; and 3dly, The tibialis anticus. muscles moving the toes. 229 CLXXXVIII. The flexor longus pollicis is small and pointed at its origin, and arises fleshy from three fourths of the fibula to within an inch of the outer ankle. It grows thicker and larger as it descends, and adheres to the tendinous parti- tions of the tibialis posticus and of the peronai. Its tendon can be seen only about an inch above the joint of the ankle. It passes down behind the inner ankle, where it is bound in a sort of annular ligament. It there passes under the heel-bone, in the arch ofthe foot, betwixt the bones and the abductor pollicis ; it then glides into the channel made by the two heads of the flexor pollicis brevis ; it then passes betwixt the two sesamoid bones at the root of the great toe ; it then goes forward in a sheath, to be inserted into the last bone ofthe great toe; at which implantation it is enlarged. Its office is to bend the great toe ; but it is also continually useful at every step in extending the foot, or in keeping the toe firm to the ground, while the gastrocnemii raise the heel ; and therefore we should not be rash in cutting away the great toe, for in it consists not the strength of the foot only but ofthe leg. CLXXXIX. The flexor longus digitorum pedis, is named, in addition, the perforans ; because, like the perfo- rans of the hand, it runs its tendons through the split tendon of a smaller muscle, which is lodged in the sole of the foot. It is named also flexor communis ; although there be less reason here, where there are no flexors for the individual toes, than in the hand, where there are separate flexors for the individual fingers. It arises from the back part of the tibia, its whole length ; that is, from the end of the popliteal muscle, and from the sep- tum tendinosum, by which it is divided from the tibialis anti- cus, Avhich lies immediately before it ; and it continues this origin from the tibia down to within three inches or so of the ankle. Its origin is not easily separated before from the tibia- lis posticus, nor behind from the flexor pollicis. The tendon is not formed till very near the ankle (within two inches of it,) and the flesh still accompanies it quite down to the joint. It crosses the tendon of the tibialis posticus be- hind the ankle-joint, and goes forward in the groove of the os calcis, tied down by a sort of capsule or annular ligament. In the arch of the foot it crosses the tendon of the flexor pollicis, from which it receives a slip of tendon ; and thus the office of either is assisted by the other, and could be wholly supplied by it; it then passes over to the middle of the sole, and growing flatter and thicker, divides into four flat tendons. These go forward, diverging till they arrive at the ends of their metatar- sal bones ; then they emerge from the aponeurosis plantaris, 230 MUSCLES MOVING THE TOES. along with the common short flexor. Now both these tendons run under a ligamentous sheath, and are included in it under the first and second bones of the toes ; and having perforated the short flexor opposite to the second joint, they are finally in- serted into the root of the third or last bone of each toe. These tendons, like the corresponding ones of the foot, seem to be slit with a sort of longitudinal fissure. The proper use of this muscle is to bend all the joints ofthe toes, but more peculiarly the last bone ; and also to extend the foot, keeping the point of the toes to the ground, consequently assisting the gastrocnemii, and all the muscles used in walk- ing, &c. CXC. The massa carnea Jacobi Sylvii, or planti pedis, is a small body of flesh, naturally connected with the flexor longus. The massa carnea arises from the lower part of the heel-bone, in two divisions; one (the external one) ten- dinous, the other fleshy. It is, upon the whole, pretty nearly of a square form ; it joins the tendon of the flexor longus be- fore its division into tendons for each toe ; and by the long le- ver that this has upon the heel-bone it must be of great assist- ance to the flexor. It is more generally considered in this light of a supplementary muscle ; by some it is considered as a dis- tinct muscle, and as the origin and first beginning of the lum- bricales pedis. Thus Cowper considers the massa carnea and the lumbrica- les as one and the same : that the massa carnea joins the ten- don, covers it with its flesh, continues fleshy along the common tendon, till at the bifurcation it also parts, along with the four tendons, into four small fleshy muscles, which are called lum- bricales. Albinus, again, paints the massa carnea distinctly termina- ting at the common tendon, and the lumbricales as arising dis- tinct from each of the divided tendons. CXCI. The flexor brevis digitorum is also named the flexor sublimis or perforatus. It arises from the lower part of the heel-bone, or the bump upon which we stand. It arises by very short tendinous fibres ; and being placed immediately un- der the plantar aponeurosis, it takes hold of it, and also of the tendinous partitions betwixt it and the two abductors of the small and of the great toe, which are on either side of it. Un- der the metatarsal bones it divides itself into four heads ; their tendons begin earlier upon the side next the foot; they grov; round; emerge from betwixt the dentations of the plantar aponeurosis ; they then pass into the vagina or sheath of each toe ; and on this, the first phalanx, they lie over the tendons of the long extensors. About the root of this first bone they di- muscles moving the toes. 231 vide into two little bands, which form a split (like the perforatus of the fingers) for the passage of the long tendon. The long tendon passes through it upon the second joint of the toe ; and immediately after the perforated tendon fixes it- self by the two forks to each side of the second bone or phalanx of the toe. Its use is to bend the first and second joints of the toes, but most peculiarly the second. And the obliquity of the long flexor is exacdy balanced by a corresponding obliquity of the short flexor: for the tendon of the long flexor coming round the inner circle, runs obliquely outwards to reach the toes ; while the short flexor coming from the heel, which is towards the outer edge of the foot, runs in a like degree obliquely in- wards, and meets the other at an acute angle near the toes. CXCII. The lumbricales must be dissected after the short flexor. They need no description, since they exactly correspond with those of the hand. They rise like them in the forks of the extensor tendons. They, like them, pass through the digitations of the aponeurosis. They pass on to the first bone of the toes, and, like the lumbricales of the hand, creep over the convexity of the bone, to be united along with the tendons of the extensors. Their insertion is always at the side of the toe next the great toe; and their use is to bend the first joint ofthe toes, and to draw them towards the great one, making an arch in the foot, and assisting the trans- versalis pedis. The extensor brevis lies most superficially upon the sole of the foot, having its origin from the inner sur- face of the aponeurosis. The massa carnea lies deeper, having no origin but from the tip of the heel-bone, and being soon implanted into the tendon of the long flexor. The lum- bricales again rise from the tendons ofthe long flexor, begin- ning just where the massa carnea ends in it; and the lumbri- cales are the flexores primi internodii; the short muscle, the flexor secundi internodii ; the long flexor, the flexor tertii internodii digitorum. EXTENSORS OF THE TOES. CXCIII. The extensor longus digitorum pedis is very- difficult to dissect from its numerous adhesions. It arises properly from the head of the tibia, at its outer and fore part, just under the knee; but it has also strong adhesions to the inner surface of the fascia ; to the tendinous partitions betwixt it and the tibialis anticus before, and betwixt it and the peronai behind ; and also to the interosseous ligament and to 232 MUSCLES MOVING THE TOES. the edge of the fibula. Its small origin soon becomes thick, and is divided even from the beginning very perceptibly into three distinct portions. These soon form three round tendons, which go obliquely inwards, pass under the annular ligament of the ankle, and run in a ring of it peculiar to them and the peronaus tertius. They then traverse the two bands of the annular ligament, upon the fore part of the foot; and now they change their direction a little, and go from within out- wards, and diverge towards their proper toes. There are three portions of muscles and four toes to be moved : the first portion divides its tendon into two at the joint; so that the first portion serves both the first and second toe, the second the third toe, and the third serves the fourth toe. Here the ten- don of the long extensor receives four other tendons ; first, of the interossai externi; secondly, of the interossai interni; thirdly7, of the long flexor ; fourthly, of the lumbricales; and these form a very large sheath, quite surrounding the toe. These do not only, like other extensors, extend the toes, but also, by the divergence of the tendon, expand them or separate them one from another. CXCIV. The peron/Eus tertius should have been de- scribed as a flexor of the foot, along with the tibialis anticus; but is so naturally connected with this, that it will be more easily understood now. It is often named peronvEus terti- us, sometimes nonus versalii, or ninth muscle of the foot. Its origin is from the fibula, chiefly from the middle down- wards ; also from the interosseous membrane ; and still from the tendinous partition which divides it from the peronseus brevis. Its origin is almost entirely fleshy ; and it lies behind and under the extensor communis, so that it seems in its belly to be a part of that muscle. Its tendon also passes along with the tendon of the extensor communis, through the same ring of the annular ligament; and there going obliquely towards the outside or edge of the foot over the shorter extensor, it expands and covers the metatarsal bone of the little toe with an expansion, and adheres to it as a flexor of the foot; and this, as well as the tibialis and other peronaei, have an oblique insertion generally into the side of the foot; or if into the sole, it is after running over the side, as over a pulley ; so that all of them tend to press down one edge, that of the ball of the great toe, to the ground. CXCV. The extensor digitorum brevis is so connected with the extensor longus, that it is natural to describe them to- gether. The extensor brevis is a small mass of flesh, some- what resembling the massa carnea and lumbricales of the foot. It is placed just where the buckle lies, upon the rising of the MUSCLES MOVING THE TOES. 233 foot, having its origin from the heel-bone, and running ob- liquely inwards. Its origin is from the outer side and fore part of the heel- bone, and also from part of the annular ligament. It is smal- ler where it arises by a short tendon from the heel-bone, but it gradually increases in size : it divides early into four heads, which are muscular, and very distinct; the two inner of which are larger, the two outer more slender : each head has already formed an oblique tendon under its flesh, which begins to ap- pear naked about half way down the metatarsal bones. These tendons cross those of the long extensor, and pass under them nearly about the end of the metatarsal bones. Then one is implanted into the .first bone of the great toe, on the inside of the long tendon under which it had turned. The second, third, and fourth tendon are inserted into their respective next toes, and the little toe is left without one. The three last of these tendons form a sort of slit; the two sides of which pass along the sides of the toes, surrounding the long tendon, something like a perforatus ; so that the three last tendons are inserted along with the long tendons into the last bone of the toes. The obliquity of this short muscle counteracts the obliquity of the long; and it serves to extend and to spread the toes, and to pull them away from the great toe. CXCVI. The extensor pollicis proprius is a very slen- der muscle, running from the top of the leg to the second joint of the great toe. It arises from the fibula a little below its head; grows tendinous as it approaches the foot; then pas- sing under the annular ligament and the cross ligament of the foot, it goes onwards to the second joint of the toe over the first. The succession in which these muscles lie under and be- hind each other is this : first, the tibialis anticus, the outer- most muscle, arises from the fore part of the tibia, nearest the fore part of the leg, at the ridge of the tibia: secondly', the extensor pollicis lies immediately behind and under the tibialis anticus : thirdly, the extensor digitorum communis lies behind that: and, fourthly', the peroneus tertius lies be- hind the common extensor like a part of that muscle. These extensor tendons are bound down by cross bands, resembling the annular ligaments of the wrist. Thc general fascia of the thigh is continued over the knee and down the leg : it is much strengthened at the knee, where it adheres to each point of bone : it descends very thick and strong over the leg, binding down and strengthening the tibialis anticus and extensor muscles. The sheath grows thinner towards the Vol. I. 2 G 234 MUSCLES MOVING THE TOES. ankle ; but where it passes over the joint, it is so remarkably strengthened by its adhesions to the outer and inner ankles, that it seems to form two distinct cross bands, which, going from the point of the outer ankle across the extensor tendons to the point ofthe inner ankle, forms a strong crucial ligament, resembling the annular ligament of the wrist; so that this which is called the crucial ligament of the ankle or foot, is plainly but a strengthening of the common sheath. The muscles of the foot are the interossei, which, in the foot, are found single on the lower surface or sole,but double and two-headed upon the upper part of the foot. The abductor flexor, and adductor pollicis, which surround the great toe, something like those of the thumb; and the abductor and flexor minimi digiti, surrounding the little toe ; and there is a small slip of muscle, the transversalis pedis, which goes across the sole of the foot. CXCVII. The abductor pollicis arises by very short tendinous fibres from the knob of the os calcis, and also from a ligament which stretches from this knob to the sheath which belongs to the tibialis posticus ; and it arises also from the tendinous partition betwixt it and the short flexor of the toes; and although it forms a beginning tendon opposite to the cunei- form bone, the tendon is not naked till it has reached the mid- dle ofthe long metatarsal bone. It unites with the short flexor of the same toe, and is inserted into the first bone or phalanx of the toe at its root. Its use is to pull aside the toe, and at the same time to bend it a little ; it also curves the foot itself; for a joint, or any loaded part, is much better supported by muscles than by ligaments ; and this arch requires support more than almost any other part. CXCVIII. Flexor brevis pollicis. This muscle is much shorter than the last, and lies betwixt the ABDUCTORand the adductor : it lies immediately upon the metatarsal bone. Its origin is by a pretty long tendon from the heel-bone, and from the os cuneiforme externum, by two separate slips, from the heel-bone, being a full inch in length ; it also adheres to the membranous partitions on either side of it. It is soon divided into two heads: one goes to the abductor, and the other goes to the adductor, to have the tendons inserted with theirs into the root of the first bone or phalanx. These ten- dons contain the sesamoid bones ; and the parting of the two heads makes a channel for the tendon of the long flexor te run in. Its use is to bend the first joint ofthe great toe. CXCIX. The adductor pollicis is the third and last por- tion of the muscle which encircles the great toe. muscles moving the toes. 235 It arises from the heel-bone by a tendon as long almost as that which it gives the abductor: it does not immediately arise from the heel-bone ; but there is a ligament extended from the heel-bone to the os cuboides, and it arises from that ligament: this is the ligament under which the tendon of the peroneus longus glides. The adductor is divided into two fleshy fasciculi or heads ; these unite, and, going obliquely inwards, are in- serted either into the sesamoid bone, or directly into the first bone of the great toe. CC. The transversalis pedis extends transversely a- cross the sole of the foot at the head of the metatarsal bones ; it is a very small muscle, and resembles a good deal the palma- ris brevis. It'arises from the ligament which connects the bones of the tarsus together; and a small muscular belly is formed, which is inserted into the tendon ofthe adductor pollicis. Its use is said to be to make a sort of gutter in the foot, by- drawing the heads of the metatarsal bones together. But is it not evident that this is one of manyr instances of muscles being a more perfect support than ligaments ?—It is a support, having a sort of intelligence, contracting or relaxing according to the necessity or degree of force : indeed, except this use, it is not easy to assign any ; for there is very little occasion for hollow- ing the foot in this direction. CCI. The abductor minimi digiti, like the abductor pollicis, is a pretty long muscle, but very slender, lying on the outer side of the foot. Its origin is from the knob of the heel-bone, and from the tendinous septum, which covers the flexor brevis : it forms two small tendons in the same direction ; one small and shorter ten- don is fixed into the metatarsal bone, at its root; the other goes forward, to be inserted into the root of the first bone of the toe : so that this muscle clearly performs both the offices as- cribed to the other flexors. It bends the toe to which it be- longs, and it extends and supports the tarsus in walking ; and it carries the toe a little outwards, from which it has its name. CCII. The flexor brevis minimi digiti is next, and is almost the same muscle in place and office : it is an exceedingly small muscle; it just measures the length of the metatarsal bone, and arises from it. Its origin is from the root of the me- tatarsal bone of the little toe, and from the ligament by which that bone is connected with the os cuboides ; its small belly runs the length of that bone ; and it is implanted by a short ten- don into the root ofthe first bone of the little toe. Its use is to bend the toe. CCJIf. The interossei interni are three small muscles 236 muscles moving the toes. seated in the planta pedis, as the interossei manus are in the palm of the hand. Their slender tendons pass through the openings of the aponeurosis plantaris ; and, going on the inside ofthe toes, are, like the lumbricales, inserted along with the extensor tendons. These pull the toes towards the great toe, bend the first joint, and extend the second and third. CCIV. The interossei externi are, like the correspond- ing muscles of the hand, four in number, and double headed, and have been named bicipites. They rise from the metatar- sal bones on each side of them : each has some little variety in its origin or course ; but it is far from being worth our while to describe each individually, as many do : it is sufficient to ob< serve their origin, and that their tendons all meet the tendons of the long and short extensors ofthe lumbricales, and of the interossei interni, upon the back of the toes ; so that the whole forms a web, aponeurosis, or sheath, which covers the upper part of the toe, and adheres to its point. The office of these muscles is to extend the toes. Plantar aponeurosis.—The palm and the sole are much exposed, and are specially defended by a thick tendinous apo- neurosis. In the palm there is the more reason to suspect ex- pansion to proceed from the tendon of the muscle, because the tendon of the palmaris is inserted into it: yet that is not pro- bable ; for the tendon is very slender, and quite unfit for the generation of so broad a sheet of aponeurosis. In the foot such an origin is still less probable ; for the plantaris tendon does not terminate in the plantar aponeurosis, but is inserted into the heel-bone. The plantar aponeurosis arises most distinctly from that part of the tuber of the heel-bone upon which we stand : it is divid- ed into three sheaths. Sabbatier makes a middle, external, and internal portion of the same aponeurosis. Albinus also describes it as three distinct aponeuroses: one for the middle of the foot; one for the abductor ofthe great toe ; and one the aponeurosis of the abductor of the little toe ; all connected to- gether only by their edges. Cowper considers it as a general expansion from the plantaris ; and it is from this prejudice that the muscle has its name. But its true origin is from that part of the knob of the heel- bone on which we stand. The middle, and more pointed ten- don, arises from the very point of the knob ; the inner fascia arises from the inside of this ; and the outer one from the out- side. And though thus divided into three heads, yet the whole origin is from the heel-bone, and is small and pointed. From this point the aponeurosis goes forward, expanding till it is as OF THE MUSCULAR POWER. 237 broad as the roots of the toes; so that the whole has the shape of a sandal; and as it expands, its fibres are more scattered, so as to have a radiated appearance. Accordingly, the part near- est the heel is thicker, while the broader part is thinner. It goes forward, like the sole of a shoe, till, having ap- proached the heads of the metatarsal bones, it is divided into five heads, corresponding with the five knobs: and each of these heads again subdivides itself into two bands ; which, passing on each side of the heads of the metatarsal bones, is fixed into the sides, so as to leave room for the passing of the tendons, and nerves, and arteries. Now, this middle aponeurosis sends down a deep strong par- tition on each side of it; which is the best reason that I know for making these three dictinct aponeuroses : for, by these per- pendicular partitions, the hollow of the foot is separated into three distinct chambers : under the middle one are concealed the tendons of the long flexors, with the lumbricales and short flexor muscles ; under the outer one, the flexor and abductor ofthe litde finger : and under the inner one, the adductor, flex- or, and abductors of the great toe. The uses of this great and very strong aponeurosis are : that it protects all the parts, the blood-vessels, muscles, and nerves that lie under it: that it supports the arch of the foot, both in standing and in motion, passing from heel to toe, like a bow- string, across its arch : that it binds down the muscles, and consequently supports and assists them in their strong actions : that it gives origin, or part of their origin, to many ofthe mus- cles ; which, by their frequent and irregular adhesion to it, are very difficult to dissect: that it forms openings or rings, in which the tendons of the other muscles pass. CHAP. IX. OF THE MUSCULAR POWER. X HAT contractile power which resides in the muscular or living fibre, is a phenomenon the most wonderful and perplex- ing of all. When we cannot reach the true point, the mind too often condescends to the most trifling pursuits : and so, when 238 OE THE MUSCULAR POWER. the older physiologists could not understand the intrinsic na* ture of this muscular power, they endeavoured to discover the size, the colour, and other external properties of the fibre ; fool- ishly desiring to know what, if known, could be of no avail. Colour was believed to be essential to the constitution of a muscle : but in fowls, in amphibious animals, in fishes, in worms, and insects, through all the gradations of animals, of different species or different sizes, the colours of the muscular fibre change. In fishes and in insects it is entirely white; even in the human body it is not essentially red ; the fibres of the iris, the muscular coats of the arteries, the muscles of the stomach, of the intestines, and of the urinary bladder, are co- lourless : the blood which makes this fibre red in the other parts may be washed away\ Then why should we define a muscle by that accidental property which it so often wants, and of which it may be so easily deprived ; while we may define k more truly by its contractile power, the only evidence of its na- ture, and its chief distinction in the syrstem ? for the contrao tion of the iris constitutes its nature ; it is a muscle by truer marks than by its colour : and, by the same rule, the muscles ofthe least insect are as perfect as the muscles of a man. Philosophers of the last age had been at infinite pains to find the ultimate fibre of muscles, thinking to discover its properties in its form ; but they saw just in proportion to the glasses which they used, or to their practice and skill in that art, which is now almost ibrsaken. Some found the fibres to be of one equal size in all creatures, however various : others found them proportioned to the size, or age, or strength, of their subject: but even such discrepancies are trivial to those which, in one of the greatest of these minute philosophers, are found almost in the same page ; sometimes affirming the ultimate fibre to be greater or smaller, according to the strength of the subject, and again making them of equal size in the whale and in the insect. Others, less troubled about the ultimate size of these fibres, have conceived notions of their form, which, in the credulity of the'times, rose into the importance of doctrines ; and, from the first raw conceptions of their authors, were finally proved by the microscope forsooth ; and while one author was drawing his rhomboidal fibres all conjoined in regular succession, and another describing them also from the microscope as consisting of six cylindrical fibres involved in a spiral one, a third reckon- ed the fibres a succession of spherical bodies ; and Cowper thought that he was injecting with quicksilver chains of bells jointed with each other. For the honour of the age, these va- nities are forgotten now. And why, indeed, should we seek OP THE MUSCULAR POWER. 239 the ultimate fibres of the muscle, or study their forms, when the discovery could not advance us one single step in the know- ledge of its nature or essence ? What avails it, that we have discovered (if we have really discovered) the shape of the particles of the' blood ; the wave-like fibres within the sub- stance of the nerves ; or the jointed appearance in the smaller fibres of muscles ? We do not understand the nature of the blood, the properties of the nerves, nor the contractile power of the muscles, at all better by the knowledge of this peculiar form of the internal structure, than we do by the grosser marks of their external form. Physiologists have, by a late sense of their own weakness, been at last humbled to this becoming, but unwilling acknow- ledgment, that this contractility of the muscles is an original endowment of this living matter derived from the Creator ; imparted in a way which we cannot know ; and so attached to the organization of the muscular fibre, that when its organiza- tion is destroyed, this power is lost. We have resigned the search after a mechanical or physical cause, and seek only to learn the properties of this living power, and the excitements by which it is moved. To this end it is necessary to define this power, distinguishing it from those feelings or motions which result from the nerves. The vis insita being that power which belongs to muscles, is the source of motion and animal life. The vis nervea, being that property which is peculiar to nerves, is the seat of feeling, and the cause of voluntary mo- tion, relating chiefly to the enjoyments and consciousness of life ; for life and motion exist even in plants, and in many creatures which, not having nerves, have neither conscious- ness nor enjoyment, and in which the place of feeling is sup- plied by a less perfect instinct by this vis insita, or some analo- gous inherent power. This irritable power residing in muscles may be defined the property by which muscles feel and re-act, upon certain stimuli being applied, without that feeling being conveyed to the sensorium; without a consciousness of action; without any other natural dependence on the system than that while certain orders of muscles are obedient to their own stimuli only, as the heart to the blood, other orders of the muscles are ready to receive the commands of the will. And above all, so little dependent is this action upon the nerves, that it is as perfect in animals which have no nerves ; and is for a time verv perfect in the parts which have been severed from the systems to which they belonged. This power, inherent in the muscular fibre, belonging to its constitution, and not derived from without, h 240 OF THE MUSCULAR POWER. the vis insita or irritability of Haller*, the vis vitalis of Goer- ter, the oscillation of Boerhaave, and the tonic power of Stahl. It is seen in the spontaneous and tremulous contrac- tions of muscles when lacerated, as in wounds ; when cut in operations ; when entirely separated from the body, as in ex- periments upon animals ; like that tremulous motion which we often feel in various parts of the body, without any evident cause, and independent of the will. Even when the body is dead to all appearance, and the nervous power gone, this con- tractile power remains ; so that if a body be placed in certain attitudes before it be cold, its muscles will contract, and it will be fixed in that posture till the organization yields and begins to be dissolved. It is by this inherent power that a cut muscle contracts and leaves a gap ; that a cut artery shrinks and re- tires into the flesh ; that the whole body shrinks and grows stiff after death. These are but faint indications of that latent power which can be easily excited to the most violent motions, and on which all the strength of the muscles depends: for the ligaments, tendons, bursae of joints, and all those parts which have no living power, are capable of bearing the same weight when dead as when alive. But such is the connection betwixt the organization of a muscle and its contractile power, that the moment it dies all its power is gone ; and the muscle which could lift a hundred pounds while alive, cannot bear the weight of a few pounds when dead. This latent power may be brought into full action by various stimuli. The latent power itself is called vis insita ; the acting power put into action, or the proof of the vis insita, upon applying stimuli, is called the irritability of muscles. This irritability is so far independent of nerves, and so little connected with feeling, which is the province of the nerves, that upon stimulating any muscle by touching it with a caustic, or irritating with a sharp point, or driving the electric spark through it, or exciting with the me- tallic conductors, as of silver and zincf, the muscle instantly contracts; although the nerve of that muscle be tied ; although the nerve be cut so as to separate the muscle entirely from all connection with the system ; although the muscle itself be se- * The irritability of a muscle is, perhaps, more properly the vis insita or in- herent power called into immediate action by the presence of stimuli: and as for the names of Tonic Power, Vital Power, and the rest, the terms are quite undefined, and may perhaps have referred rather to the combined effect of all the powers ot life, and of all the properties of inanimate matter, of nervous sympathy, elaiticity, and of muscular power combined. f See a most ingenious dissertation by my pupil Mr. Fowler, the first writer, in this country, on this very interesting novelty, where the operations of thisjnew excitement are explained. OF THE MUSCULAR POWER. 241 parated from the body ; although the creature upon which the experiment is performed may have lost all sense of feeling, and have been long apparendy dead. Thus a muscle cut from the limb trembles and palpitates for long after; the heart sepa- rated from the body contracts when irritated; the bowels, when torn from the body, continue their peristaltic motion, so as to roll upon the table, ceasing to answer to stimuli only when they become stiff and cold ; and too often in the human body the vis insita loses the exciting power of the nerves, and then palsy ensues ; or, losing all governance of the nerves, the vis insita, acting without this regulating power, falls into partial and general convulsions. Even in vegetables, as in the sensi- tive plant, this contractile power lives. Thence comes the dis- tinction betwixt the irritability of muscles and the sensibility of nerves ; for the irritability of muscles survives the animal, as when it is active after death ; survives the life ofthe part, or the feelings of the whole system, as in universal palsy, where the vital motions continue entire and perfect, and where the muscles, though not obedient to the will, are subject to irregu- lar and violent actions ; and it survives the connection with the rest of the system, as where animals very tenacious of life are cut into parts:—but sensibility, the property of the nerves, gives the various modifications of sense, as vision, hearing, and the rest; gives also the general sense of pleasure or pain, and makes the system, according to its various conditions, feel vigorous and healthy, or weary and low. And thus the eye feels, and the skin feels ; but their appointed stimuli produce no motions in these parts ; they are sensible but not irritable. The heart, the intestines, the urinary bladder, and all the mus- cles of voluntary motion, answer to stimuli with a quick and forcible contraction ; and yet they hardly feel the stimuli by which these contractions are produced, or at least they do not convey that feeling to the brain. There is no consciousness of present stimulus in those parts which are called into action by the impulse of the nerves, and at the command of the will; so that muscular parts have all the irritability of the system, with but little feeling, and that littie owing to the nerves which enter into their substance; while nerves have all the sensibility of the system, but no motion. The vis insita is a power that is in continual force, pre- serving the parts ready for their proper stimuli, whatever these may be ; one set obeying their own peculiar stimuli chiefly ; while others are obedient to the nervous power and the influ- ence of the will. The heart is stimulated by the quantity or quality of its blood ; the stomach by the presence of food ; the intestines by their contents : the urine stimulates the bladder ; Vor.. I. 2 H :342 OF THE MUSCULAR POWER. the venereal appetite stimulates the genital system; the fatus stimulates the womb; and the voluntary muscles (if we may- be allowed to guess at a thing so litde known) are excited; by the nerves, and so are obedient to the will; for, to our limited j. view, the nerves seem to be the sole messengers of these com- mands ; and any stimulus to the nerves moves«the muscles like the commands of the will. The absence of the due stimulus to each, or the presence of ordinaiy stimuli in too great power, will excite enormous and irregular motions ; as fulness of blood in the heart, poisons in the stomach, acrimonies in the intestin- al canal, or the passions of anger or fear in the system of the vo- luntary muscles. The due stimuli preserve their right tone and action ; but these violent stimuli hurt their irritability or moving power ; the heart acts weakly after fevers : the appe- tite is languid after debauch; the limbs are weakened by la- bour ; and the whole system is ruined by excess. Thus the functions by which the system lives, the heart, the stomach, the bowels, and the womb, the various sorts of vessels by which the fluids are conveyed, are providently removed from the influ- ence of the will; for these are the machines of the system, whose motions coidd not stop, must not be interrupted, nor lowered, nor raised, but must move and act according to the needs of the system. Not left to the irregularities or careless- ness of voluntary motions, they are governed each by its own peculiar stimulus, and act in a continued and equal course. Thus there are in the body two living powers which are as cause and effect in all the motions of our system. The nerves stand as an intermedium betwixt all external objects and our general sense ; by the impressions through these come pleasure and pain, and all the motives to action ; by the will, returned through the nerves, all voluntary motions ensue." Thus are the nerves, as internuncii, betwixt the external impression and the moving power. But nerves were never known to move under the influence of stimuli; the moving power is another property of a distinct part of our body, having its own arrangement of particles, and its own peculiar form. All motion then pro- ceeds from the joint operation of either power ; the nerves con- vey the impressions, while the muscles contain the power; and it is here, as in other natural effects, the external cause changes, while the inherent property, the subject of its operation, re- mains the same. The nervous power is the regulator of the system ; it is the property suited to all the supports of life, up- on which they act, and by which they maintain their power over our body : but it is subject to continual changing ; it rises and falls, is perfect or low ; but the energy of the muscle, which is to answer to this power, remains ever the same while its organ- OF THE MUSCULAR POVVER. 243 ization remains ; the nervous power is exhausted and languid; but the muscular power is always perfect, always ready for the excitement of stimuli or for the commands of the will. There is (if we may be allowed any expression so loose and indefinite) the will of the system, and the will ofthe mind : it is the will of the'system that, through the medium of nerves of wide sympathy and consent, governs and leads in harmony all the consenting functions of the body, and lowers and raises their powers, according to the weakness, or strength, or fulness, or wants of the body; while the will ofthe mind commands those voluntary motions, which it is its choice to perforin. So natural seems that notion which has long prevailed of an archseus, or presiding spirit, which, like a latent instinct, regulates and pre- serves the system, prompts to what is right, and creates an a- version to what is wrong, and raises or allays the actions of the vital organs, preserving the system in health, and striving against disease. The voluntary muscles are put under the command ofthe will, while the involuntary muscles, by which the vital organs move, are insulated and mechanical, and de- pend less on our spiritual part : for life and existence depend less on feeling, or that which is allied to our spiritual part, and more on the irritable or moving power ; and it was fit that this irritable power should be divided from our feelings and our will, which are irregular and transitory, and apt rather to de- range than to preserve the system. How this division is accomplished we do not know in any surer way ; but we see that the heart, the lungs, the stomach, and the intestines, have a proportion of nerves, so much lower than the muscles of voluntary motion, that the very existence ot these nerves has been denied. Yet there are nerves proper to the vital parts : the phrenic nerve goes to the diaphragm ; the par vagum to the stomach and bowels ; the sympathetic nerve to the heart; they are smaller, but they are appropriated and distinct. Now this question occurs : "if the irritable pow- er be in these organs, if they be endowed with the quality of feeling their own peculiar stimuli, and answering to their im- pulses, what need is there for nerves ? But they also have their nerves, that they may not want some living connection with that system to which they belong ; that they mav flourish in its health, and languish in its diseases; that they may act according to the needs, and be subject to the will ofthe system ; that the grand movers ofthe mechanical system may be affected in their turns by the spiritual part, and thus the digestion, the circula- tion, the venereal appetite, and every vital power are languid and depressed, or lively and perfect, according to the conditions of the whole : and how these functions are moved by anger, or 244 OF THE MUSCULAR POWER. joy, or fear, needs not be told. But the vital functions also lose their action: " The heart acts weakly after fevers ; the appetite is languid after a debauch ; the limbs are weakened by labour; and the whole system is ruined by excess. These organs have less dependence on nerves; and so suspicions arise, that the irritable power, the very basis of life, may also fail: but how should it fail ? If the motions of our system cease, it must be either from the incapacity of the muscles, or from the loss of exciting power in the nerves. The nerves are liable to change, but the muscle retains its power till its organization be destroy- s ed. When the irritable power of a muscle ceases, when the heart, for instance, begins to fail, whence can that loss arise ? Its power is not mechanically exhausted, else from what source could it ever be renewed ? It is not from any injury to its nerves ; for the heart, when cut out from the body, may be wearied out with constant stimuli till it cease to act; and it will recover by rest, without communication with the nerves : but it is perhaps such a derangement as happens in a spring, which, being long bent, loses of its elastic power : the arrangement of its particles suffers by straining ; they are composed by rest: and if the elastic power be thus restored in an inanimate spring, much more should the contractile power recover by rest in the muscular fibres of a living system. The vis insita cannot be wearied nor exhausted; so the heart is unwearied in its function, or if languid or too violent in its actions, that must be from the power of stimulus being lowered or increased, not from any change on the inherent pow- er. The voluntary muscles also are unwearied ; and so, after great fatigue, we are sensible of cramps and irregular contrac- tions, showing that they are still active, but more loosely go- verned by the nerves, and not so fully under the command of the will. But the nervous system is more subject to weari- ness and to decayr: the senses become tired; the feelings of the system are exhausted. It is from this failing of the ner- vous power diat violent exertions bring fatigue and pain; from this also that we need the refreshment of sleep ; but during sleep, the heart, and all the involuntary muscles, unwearied in their functions, proceed still in the same regular and orderly course. This irritability or inherent power not only keeps the mus- cles ready, each for its peculiar stimulus, but preserves a bal- ance over the whole system of the muscles. We know that muscles maintain a constant action independent of the nerves. The muscles of one side balance the opposite muscles : and if the muscles of one side be relaxed by palsy, the action of the opposite muscles instantly appears : or if a limb be luxated, and OF THE MUSCULAR POWER. 245 its muscles displaced, they persevere in a violent and spasmo- dic action till they be restored each to its place. Have we not reason to believe, that if muscles were absolutely and entirely quiescent, they could not be so instantaneously called into ac- tion ; but that by this continual tension or tone they more rea- dily follow the commands of the will: that by this lesser ten- sion they are prepared for greater action, and inclined to har- monize : for if all the muscles were quiescent, and one sudden- ly moved by the will, its antagonist would rise into undue ac- tion, and the co-operating or assisting muscles would be un- prepared. Whereas, by this continual tension of all the mus- cles, one set is opposed to another, is consenting with it, and is ready to co-operate with it, or to oppose it in the due degree : the mind has but to incline the power towards one set, and im- mediate and orderly motions ensue. The nervous influence, again, is as a mere stimulus to the voluntary muscles, as blood is to the heart, or the fcetus,' or any foreign body, to the womb. It loses its influence over the system faster than the ordinary powers of life do ; and the irri- table state of the muscles continues long after the voluntary' motion, or the power of excitement from the nerves, is gone : for when we die slowly this inherent power is exhausted in the struggles for life. If, while in perfect health, we are killed by a sudden blow, the irritable power of the muscles survives the nervous system many hours or days, and the flesh trembles, and the absorbents continue to absorb ; and often, as after suf- focation, we can, by operating upon this poor remains of life, restore the circulation, re-animate the nervous system, and re- cover that life which seemed to have entirely left the body; and thus the nervous influence, which seemed to animate the sys- tem, and to be the prime mover and source of life, owes its res- toration to-that which was thought to be hut a secondary pow- er. It is this remains of contractile power which fixes the dead body in whatever posture it is placed : it is this remains of irri- tability which preserves freshness in the animal which seemed dead, but which is really dying still: for the moment this lin- gering portion of life is gone, the body dissolves, and falls down; and so we judge of freshness by the rigidity of the flesh, and foresee approaching putrefaction by its becoming soft. There is no putrefaction in creatures suddenly killed, as in the accidents which happen to man, or in killing animals by a sud- den blow ; in these the body continues fresh and susceptible of stimuli long after death : but if this inherent power, this irrita- ble nature ofthe fibre, be exhausted before death, or in the mo- ment of-death, then does the body fall quickly into the condi- tion of dead matter, running through those changes which are 246 OF THE MUSCULAR POWER. the only true marks of death. The fish, which is allowed to struggle till it be dead ; the ox, over-driven before it be brought to the slaughter; the animal killed by lightning, which sud- denly explodes (if we may be allowed the expression) all the powers of life—in these the contractile power is effectually ex- hausted ; no mark of irritability remains ; putrefaction comes quickly on: and so in those who die of the plague, of poison, of fevers, or of any sudden and violent disease, which at once extinguishes life, in the vulgar sense, and robs the system of that remnant of life which the physiologist could produce to view; in all these cases, the body becomes putrid in a few hours. If a body becomes putrid so early in warm climates, it is not merely because putrefaction is favoured by heat; but it is be- cause heat exhausts the vital power, and often a part of the body has lost its organized power, and is almost putrid, before the whole be dead. We find that we are wrong in this, that when a body has lost all feeling and motion, we pronounce it dead; the nerves indeed have ceased to do their office; all feeling and consciousness is gone ; but the mere animal power survives the nerves, and through it the whole system may be re-called into perfect life. The powers and privileges ofthe nervous system must not be ranked too high nor valued too low : the perfect animal feels and moves by the nervous power ; but surely its muscles are actuated by a law of their own nature : the heart of the chick begins to move before we dare presume that there is any organ for distributing this nervous power. The punctum saliens is the heart of the chick ; it is seen beating wdiile the body of the chick is but a rude, unformed, and gelatinous mass ; daily this active centre increases in strength and power ; and it has a del- icate feeling of stimuli, and it quickly re-acts, so as " to fly out into angry and perturbed motions" by the application of a sti- mulus. It is excited by increased heat, and languishes when cold, till at last it dies ; then it ceases to act, but still heat re- stores it to life : and is not the proof stronger in the grown an- imal, when we cut out the heart, which answers to stimuli for some time ; at last seems to have its power exhausted; it lies dead for some time, till it again recovers its power. If this power proceeded from the nerves, how could it be renewed ? but if it reside in the muscle only, it may have been wearied, and may revive : its organization may have been deranged, and may be restored by rest from stimuli; and its parts may be composed again, resuming their relative situation, and their ac- tive arrangement and form ; or though it may be insensible to a stimulus long applied, it may be still alive, even to a lower stimulus of another kind ; or it ma}- awake again to the feeling OF THE MUSCULAR POWER. 247 of that stimulus, which, by being too long applied, had lost its power. Sensibility depends upon the nerves ; motion on the mus- cles : both are equally admirable and inscrutible ; the one con- ducing to all the enjoyments, and all the sufferings of life, and to the intellectual faculties of man; the other being the chief support of animal life, and the source of all the bodily powers. As for the mechanical powers, by which the contraction of the muscular fibre is forwarded or retarded, they are not what they have been believed ; for we find few circumstances in die origin, insertion, or forms of muscles, to favour their power, but many by which their power is abridged. There are certain points where the length of lever gives an increase of power. The mastoid process, and the occiput, are as levers for the head; the spines ofthe vertebrae, for the back ; the ole- cranon, for the arm ; and the pisiform bone, for the hand. The pelvis and the jutting trochanters, are as levers for the thigh ; the patella is a lever for the leg ; the heel-bone is a lever for the whole foot; and the arch of the foot is as a lever for the toes. These are not the whole, but they are perhaps the chief levers in the human body. In all the other implantations the muscle is fixed, not behind the joint, but betwixt the joint and the weight that is to be moved. There is a greater loss of power when inserted near to the joint; there is less loss of power when the tendon is inserted far from the joint; and though we call such insertion a longer or shorter lever, there is always some loss of power, and the true levers in the body are veiy few.— Far from providing mechanical forms to increase the power, nature has provided such a quantity of contractile power as to compensate for any loss of effect: so, in place of increasing the effect of muscles by levers, pulleys, and hinges, there is in al- most every muscle a great abatement of its force by the form of the bones which it is destined to move ; for muscles lose of their effect by their being implanted, not behind the joint, but betwixt the joint and the body to be moved ; by the insertion of almost all muscles being very oblique, with respect to the motions which they are to perform ; so that half their force is lost upon the immoveable end of the bone. Much force is lost by a muscle passing over many joints : one set of fibres in a muscle hinders the action of adjoining fibres, and every degree of contraction takes from that muscle an equal proportion of its power. Thus, every where in the human body, is power sacrificed to the form and fitness of the part; that the joints may be smaller than the limbs ; that the limbs may be propor- tioned to the body: and beauty and conveniency is gained by the sacrifice of that power which is not needed in the system, 248 OF THE TENDONS, since the wisdom and goodness of the Creator has appointed a degree of force in the muscles more than proportioned to all this loss of the mechanical power. Those who will admire thc ways of Providence, should know how to admire ! Nature is not seeking to compensate for want of power, by the advanta- ges of pulleys, and levers, and mechanical helps ; nor is it in the forms ofthe parts that the Infinite Wisdom is to be found: for among other gifts, such a portion of this spirit is given to man that he has used the pulleys, and levers, accelerations of mo- tion, and all the mechanical powers that result from it; he has invented valves of infinite variety, each perfect and true to its particular office ; he has anticipated all that he has found in the mechanism of the human body ; but the living power which compensates for the want of levers, which allows every where power to be sacrificed to the beauty of form, which has strength in convulsive and violent actions to break the very bones ; this is the act of Infinite Wisdom, on which our admiration should chiefly dwell. It is but the very elements of so deep a subject that can be delivered here. I must proceed to explain those provisions for easy motion, which may be considered as belonging to the muscles and bones, and as preparing us for a knowledge of the joints. <&> CHAP. X. OF THE TENDONS, LIGAMENTS, BURS^, AND ALL THE PARTS WHICH BELONG TO THE BONES OR MUSCLES, OR WHICH EN- TER INTO THE CONSTITUTION OF A JOINT. 1 HE bones and muscles themselves are but the smallest part of that beautiful mechanism by which the motions ofthe human body are performed; for the parts by which the bones are join- ed to each other, or the muscles fixed into the bones, are so changed and varied in their forms, according to the uses of each part, as to give a natural and easy shape to the limbs, se- curity and firmness to their motions, and lubricity and smooth- ness to the joints by which these motions are performed : and this apparatus deserves our attention, not merelv that we-may LIGAMENTS, BURSAE, &C 249 know the forms of these joinings, but that we may learn something of the nature and uses of each part, and the vari- ous degrees of sensibility with which each is endowed; for 'from this kind of study conclusions will arise which may lead us to the knowledge of their diseases, suggesting the means of their prevention and cure. There is a difference in the parts of the human body, ac- cording to the several uses for which they are designed; some are vascular and soft, others bony and hard; some sensible, and very prone to inflammation and disease, others callous and insensible, having little action in their natural state, and little proneness to disease. The greater part of the human body is merely inanimate matter, united into a moving and perfect whole, by the system of the nerves which abound in each creature according to its wants, and are distributed in each system according to the uses and functions of every part. In some places there is such a conflux of nerves as form the most delicate and perfect sense, endowing that part with the fullest life ; while others are left without nerves, almost inani- mate and dead ; lest feeling, where it ought not to be, should derange the whole system. The living parts of the system are the muscles and nerves ; the muscles to move the body, and perform its offices, each muscle answering to its particular stimuli, and most of them obeying the commands of the will; the nerves to feel, to suffer, and to enjoy, to issue the commands of the will, and to move the muscles to action: but still the muscles have their own peculiar kind of life, superior to the nerves, and inde- pendent of them, always acting, always capable of greater action, always ready to receive the impulse of the nerves. It is a power which survives that of the nerves, acting even when severed from the general system ; and acting often on the living body without the impulse of the nerves, and some- times in opposition to the will. The dead matter of the system joins diese living parts, and performs for them every subservi- ent office; forms coverings for the brain; coats for the nerves ; sheaths for the muscles and tendons ; ligaments and bursa? ; and all the apparatus for the joints ; unites them into one whole by a continued tissue of cellular substance, which from part to part through all its various forms, has no interruption, and suffers no change, but still preserves its own inanimate nature, while it joins the living parts to each other. The ten- dons, ligaments, periosteum, and bursae, are all composed of this cellular substance, which by its elasticity binds and con- nects the parts, and bv its dead and insensible nature is less ex- Vol. I. 2 1 250 OF THE TENDONS, posed to disease, and is a fitter medium of connection for the living system. OF THE FORMS OF THE CELLULAR SUBSTANCE. Under various modifications and shapes this dead matter performs most important offices among the living parts:—1. It forms cells over all the body, which allow the parts to glide and move easily ; which contain the fluid that makes all the motion of parts more easy and free ; which store up fat to fill the interstices, to support the parts in their action, to give a plumpness to all the body, and to be reabsorbed for the needs and uses of the system. This cellular substance is peculiarly useful to the muscles ; dives in among them ; keeps their fibres* at such due distance that each may have its action ; supports and lubricates them ; so that perhaps the difference of strength, in health and disease, depends, at least in some degree, upon this support. The thinner halitus makes the play of the fibres easy and free ; and the fat not only supports the fibres in their action, but lubricates them so, that a want of it is painful, while a superabundance of it incumbers the body. And Hal- ler seems to have believed, that a diseased increase of it might not only oppress, but almost annihilate, the muscular fibre. 2. But it is still further essential to a muscle, that while it moves, it should neither be hurt itself nor harm the surround- ing parts. Therefore, where one muscle moves over another muscle, soft flesh upon soft flesh like itself, there can be no hurtful friction, and the cellular substance is loose and natural, preserving its common form. But where tendons rub upon tendons, or bones upon bones, or where tendons rub upon muscles, or upon each other; some defence is needed, and the cellular substance assumes a new form. The cells are run to- gether into one large cell, with thicker coats, and a more co- pious exudation; so that, being more liberally bedewed with a gelatinous mucus, it prevents the bad effects of friction, and is called a bursa mucosa, or mucous bag. These mucous bags are placed under rubbing tendons, and chiefly about thc greater joints ; some are large and others small; their glairy liquor is the same with that which bedews the cellular sub- stance or the cavities of the joints ; and the provision of na- ture is so perfect, that the occasions which require bursae seem to form them by friction out ofthe common cellular substance. 3. It is often useful that an individual muscle should be en- closed in a tendinous sheath, to give it strength and firmness, and to preserve it in its shape. All muscles, or almost all LIGAMENTS, BURSvE, &c. 251 muscles, form for themselves individual sheaths, such as are seen inclosing the supra-spinatus and infra-spinatus of the scapula ; the biceps humeri, and most of the muscles of the leKand thigh; but it is especially necessary that the whole muscles of the limb should be inclosed in some stronger mem- brane than the common skin, both to give form to the limb and strength to its muscles, and to keep the individual muscles in their proper places, which otherwise might be luxated and dis- placed. And so the trunk of the body, the arm, the thigh, the lee, are bound each with a strong, smooth, and glistening sheath, formed out of the cellular substance, condensed and thickened by continual pressure. And this also is thicker and stronger according to the need that there may be for such a help ; for it is weaker over the flat muscles of the back or ot the abdomen, stronger on the arm, stronger still over the strong muscles of the thigh. It is hardly to be distinguished in the child; grows thicker and stronger as we advance in years and in strength, and in the arms of workmen it grows particularly thick and strong, increasing in the back, shoulder, or limbs, according to the particular kind of labour. These are the membranes which, by inclosing the muscles like sheaths, are called the vagina, or fascia of the arm, the leg, the thigh, &c. 4. Tendons or ropes we*e needed, for the muscles could not be implanted thick and fleshy into each bone without a de- formity of the limbs, and especially of the joints ; which would have been not unshapely only, but which must have abridged them of their motions and uses. Where a muscle is not implanted directly into a bone, tendons are seldom re- quired ; and so there are no tendons in the heart, the tongue, the oesophagus, the stomach, intestines, or bladder. But where tendons pass over bones, or traverse the joints, their force is concentrated into narrower bounds ; and long tendons are fixed to the ends of the muscles to pull the bones : these tendons were once believed to be but the collected fibres of muscles, gathered into a more condensed form ; by which condensation their properties of feeling and motion were lost, while they became hard, white, and glistening; and it was believed that parts which were fleshy in the child became ten- dinous in the adult. But wre know by the microscope that the tendon is not truly continued from the flesh ; that the fibres of the tendon and of the flesh are not in the same line, the fibres of all penniform muscles running into their tendon, in a direc- tion more or less oblique ; and good anatomists have been able to separate the tendon from the flesh, without any violence, and with the bluntest knives. Muscles are irritable and have 252 OF THE TENDONS, nerves ; tendons are quite dead, have no visible nerves, have neither feeling nor motion, nor any endowment by which we should believe them to be allied to the living parts of the system; and many tendons, as the expansion of the palmaris, may be unravelled into mere cellular substance. 5. The periosteum is merely a condensation of the com- mon cellular substance, formed in successive layers : and the tendons are of the substance of the periosteum ; they mix with the periosteum, and are implanted into it. In dissecting a child, we tear up the periosteum along with tendons, and without hurting the bones ; but in process of time, the peri- osteum, and consequently the tendons, are inseparably fixed to the bones. The periosteum, tendons, fasciae, and bursa mucosae, are all of one substance, and of one common nature; they are various modifications of that dead matter which, having but little vascularity, and no feeling, and hardly any disposition to disease, is the fittest for its office, and bears the roughest usage in our experiments, and the most violent shocks in the motions of the body, without any signs of feeling, and without falling into disease. 6. These tendons must be bound firmly down ; for if they were to rise from the bones during the actions of the musdes to which they belong, the effect of contraction would be lost, and they would disorder the joint, starting out in a straight line from bone to bone like a bow-string over the arch of a bow. The same inanimate substance still performs this office also ; for the tendons of one muscle often split to form a sheath or ring for the next; or their tendons after taking hold of the bone, spread their expansion out over all the bone, so as to form an entire sheath for the finger and toe ; or there is a wide groove in the bone which receives the tendons, and it is lined with a cartilage and with a lubricated membrane ; the mem- brane comes off from the lips ofthe groove, or from corners or edges of the bone, passes over the tendons so as to form a bridge, or often it forms a longer sheath, as in the fingers, or where the peronaei muscles pass behind the ankle ; and thus the vagina or sheaths of the tendons are connected with the tendons, periosteum, and other modifications of the com- mon cellular membrane. 7. The periosteum, which has run along one bone, leaves it at the head, and forming a bag for the joint, goes onwards to the next bone. Thus the periosteum of all the bones is one continued membrane, passing from point to point: each bone is tied to the next by its own periosteum ; and this membrane betwixt the end of one bone and the beginning of the next, is so thickened into a strong and hard bag, as to form the capsule LIGAMENTS, BURSiE, &C 253 of the joint; and the periosteum is assisted in performing this office by the tendons, fasciae, burs*, and ail that confusion of cellular substance which surrounds the joint. The capsule of the joint is then a firm and thick bag, which, like a liga- ment, binds the bones together, keeps their heads and pro- cesses in their right places, contains that glairy liquor with which the heads of moving bones are bedewed, and prevents the adjacent parts from falling inwards, or being catched be- twixt the bones in the bendings of the joints. The capsule of every joint proceeds from the periosteum, and is strengthened by the tendons; it is formed like these parts, out of the cellu- lar membrane ; and when a bone is broken, or its periosteum destroyed by any accident or disease, when a tendon snaps across, when a joint is luxated, and the capsule torn, the in- jury is soon repaired by a thickening of the cellular substance round the breach ; and wherever a bone, being luxated, is left unreduced, a new socket, new periosteum, new ligaments, and new bursae, are formed out of the common cellular substance ; and though the tendons may have been torn away from the head of the bone, they are fixed again, taking a new hold upon the bone. 8. There are other ligaments of a joint which prevent its luxation, guarding it at its sides, or round all its circle, accord- ing to its degree of motion: and those ligaments are of the same nature with the first or bursal ligaments ; arise, like them, from the periosteum chiefhy ; or indeed are truly but a thickening of the bursal ligament at certain points. The universal connection of these parts is now sufficiently explained, since we have followed the several forms of cellular substance: 1st, Clothing the bones with a thick membrane, which, though insensible, and almost inanimate in its own na- ture, conveys blood-vessels, the means of life, to the bones, and is named periosteum : 2dly, The same periosteum, thick- ened and strengthened by the adhesion of surrounding parts, so as to form the capsules for the joints : 3dly, The tendon, also continued from the periosteum, and not growing from the muscle, but merely joined to it: 4thly, We see that smaller tendon, expanded into a thinner tendinous sheet, as in the brawn of the leg where the ham-strings (whose expansion strengthens the knee-joint) go down over the muscles of the leg: 5thly, We see the perpendicular partitions of this fascia going down among the muscles, and dividing them from each other ; and the cellular substance, which lies under the fascia, and immediately surrounds the muscle, cannot be distinguished from the inner surface of the fascia itself: 6thly, And as for die bursae, we see that thev are formed w hercver a tendon rubs 254 OF THE tendons, over a bone. The upper surface of the bursa is formed by the tendon which rubs over the bone; the lower surface of the same bursa is formed by the periosteum of the bone which it defends ; the sides are formed by the common cellular sub- stance. Its cavity appears to be merely an enlarged cell; and the bursae mucosae and capsular ligaments are plainly of one and the same nature ; their liquors are the same ; they often open into one another naturally, or if not naturally, at least it is no disease, since no bad effects ensue. I must now explain more fully the constitution and nature of all the less feeling parts : for what I have said might be thought to imply absolute insensibility and total exemption from disease or pain ; whereas the sensibility of tendons, liga- ments, bursae, and joints, stands on the same footing with the feeling of bones : they are insensible in health ; not easily in- jured.; entering slowly into disease ; but their diseases are equally dreadful from their duration and from their pain: for by inflammation their organization is deranged, their healthy consistence destroyed, and their sensibility excited in a dread- ful degree. The tendons of animals have been cut or pierced with em- bowelling needles ; they have been pinched with nippers, and torn and cauterised ; they have been burnt with a lighted stick, while the creatures neither struggled nor shrunk from the irri- tation, nor ever gave the smallest sign of pain. Oil of vitriol has been poured upon each of the parts belonging to a joint, and a piece of caustic has been dropped into its cavity, but still no pain ensued ; nay, some have been so bold, may I not say so vicious, as to repeat these experiments upon the human body, pinching, pricking, and burning the tendons of the leg, and piercing them with knives, in a poor man, whose condition did not exempt him from this hard treatment; who was ignorant of this injustice that was done to him, while his cure was pro- tracted, and he was made a spectacle for a whole city. With- out such cruel and inhuman practices, we do not want oppor- tunities of knowing, that, in the human body also, the tendons and bursae have no acute feeling. When we cut open a fascia or tendinous membrane, there is litde pain : when (as in ampu- tation) wc cut the ragged tendons even and neat, there is no pain : when we snip with our scissars the ragged tendons of a bruised finger to cut it off, the patient does not feel: when we see tendons of suppurating fingers lying flat in their sheaths, we draw them out with our forceps, or touch them with probes, without exciting pain : in the old practice of sewing tendons there was some danger, but no immediate pain: when we cut LIGAMENTS, BURSjE, &c. 255 down into the cavity of a joint, still the pain is but slight. In a luxation there is comparatively little pain. There is no pain when the ligament of the patella is broken away from the tibia, nor when the great Achillis tendon is torn. There is but little pain in the moments of those accidents which appear slight in the time, but which turn out to be the most dreadful sprains. Yet after rupture of the patella, the knee inflames and swells : after rupture ofthe Achillis tendon, there is swelling and inflam- mation, with such adhesion of the parts as makes the patient lame : after the slightest sprain such inflammation sometimes comes on as destroys the joint. There is but litde pain when we first make an opening into any joint; yet it often brings on such pain and fever that the patient dies. In short, every thing conspires to prove, that though in wounds ofthe less fee- ling parts, there is indeed future danger, there is no immediate pain. Still there are many accidents which prove to us, that even in health the joints are not entirely exempted from pain: a smart stroke on the knuckles, or a blow on the elbow, or a fall upon the knee, are not perhaps the purest instances of feeling in joints ; for such blow may have hurt some external nerve : but when a small moveable cartilage forms within the joint of the knee, though it be small and very smooth, and lodged fair- ly within the cavity of the joint, it often gets betwixt the bones, causing instant lameness ; the moment it causes this lameness, it brihgs dreadful pains : the pain, the lameness, and all the feeling of inconveniency, subside the instant that this cartilage is moved away from betwixt the bones ; and the joint continues easy till this moving cartilage chances again to fall in betwixt the heads of the bones. Even the pain from a. blow upon the knee, for example, is plainly within the joint, and is caused by the force with which the patella is struck down against the ends ofthe bones. What indeed is a sprain, but a general violence and twisting of all the parts which compose the joint ? These parts are of one common nature, and may be arranged and enu- ' merated thus : a joint is composed of the heads of the bones, swelling out into a broader articulating surface, and of a thin plate of cartilage, which covers and defends the head of each bone ; sometimes of small and moveable cartilages which roll upon the bones, and follow all the motions of the joint, and, like friction-wheels in machines of human invention, abate the bad effects of motion. There are mucous glands, or rather mucous bags, which convey a lubricating fluid : and there is a bursal ligament, which forms the purse of the joint, binds the bones together, contains the synovia, and prevents the surrounding parts from being catched in the joint: there are lesser liga- 256 OF THE TENDONS, ments on the outside of this, going along the sides ofthe joint, and passing from point to point -. there are great tendons mo- ving over the joint and bursae, or mucous bags, which accom- pany these tendons, and prevent the violence which their con- tinual rubbing might do to the bones. All these parts are of one constitution and nature ; we cannot say that they are in- sensible, for their feeling is only deferred ; it is slow, but not the less severe. The eye feels "the instant that a mote falls up- on it; but the skin does not feel a blister till it has been some hours applied ; the ligaments and joints feel still less in the in- stant that any injury is done: but as the inflammation of the blister excites the feeling, and destroys the fabric ofthe skin, producing pain and derangement of its parts, the inflammation of joints, and of all the parts belonging to them, breaks up the organization of the part, evolves the feeling, and then in them also comes disease and violent pain. They are slow in entering into action ; but, once excited, they continue to act with a per- severance quite unknown in any other part of the system.— Their mode of action, whatever it may be at the time, is not easily changed: if at rest, they are not easily moved to action, and their excessive action once begun is not easily allayed.— The diseases are infinite to which these parts are subject. They are subject to dropsical effusions ; they are subject to gelatin- ous concretions ; they are subject to slight inflammation, to suppuration, to erosions of their cartilages, and to exfoliation of their bones: corresponding with the dropsies, suppurations, and mortifications of the softer and more feeling parts. Rheu- matism is an inflammation round the joints, with a slighter effusion, which is soon absorbed : chronic rheumatism is a te- dious and slow inflammation, with gelatinous effusions round the tendons, and permanent swelling and lameness of the joints. Gout in a joint is a high inflammation, with a secretion of ear- thy matter into its cavity. The inflammation of tendons is sprain : effusions of gelatinous matter round them is ganglion: suppurations in the tendinous sheaths is whitloe : the inflam- mation of bursae is false white swelling, not easily distinguish- ed from the true: the disease of the joint itself is either a drop- sy^, where the joint, though emptied byr the lancet, is filled up again in a few hours, showing how continual, and how profuse, both the exhalation and absorption of joints naturally is ; or it is white swelling, which, next to consumption, is the most dreadful of all scrophulous diseases, which begins by inflam- mation in the joint itself, is marked by stiffness, weakness, loss of motion, and pain ; which goes on through all the stages of high inflammation, dreadful pain, destruction of cartilages, en- LIGAMENTS, BURSjE, &C. 25r largement of bones, foetid suppurations, and spontaneous open- ings of the joints; which sometimes stops by an effusion of callus and concretion of the bones, forming a stiff joint, but which oftener ends in hectic fever, diarrhoea, morning sweats, and extreme weakness; so that the patient dies, exhausted with fever and pain. Vol. T. 2 ^ BOOK III. OF THE JOINTS. ,o< CHAP. I. JOINTS OF THE HEAD AND TRUNK. JOINTS OF THE HEAD AND SPINE. Xl-LMOST every thing relating to the heads and processes ot the bones, and every proposition concerning the motions which they have to perform, has been already explained, anti- cipating much of the anatomy of the joints : and the principles of motion mentioned in describing the bones shall form the chief propositions on which my descriptions of joints shall be arranged, seeking that method chiefly by which the joints may be easily and rapidly explained ; for it is a subject on which volumes might be bestowed, and not in vain. We may compare in the following order, the chief motions of the head and trunk. The head is so placed upon the oblique surfaces ofthe atlas, that it cannot turn in circles ; but at that joint all the nodding motions are performed. The atlas rests so upon the dentatus, that there all the turning motions are per- formed. The neck and loins have their vertebrae so loosely framed, with such perpendicular processes and easy joints, that there all the bending motions are performed ; while the back is fixed, or almost fixed, by its connection with the ribs, and by the obliquity and length of its spines; and though upon the whole, the spine turns many degrees, yet it is with a limited and elastic motion where the whole turning is great but the movement of each individual bone is small. JOINTS OF THE HEAD AND SPINE. 259 To secure these motions, we find, 1. The occipital condyles received into hollows erf the adas, where the oblique position of the condyles secures the joint, the occipital condyles looking outwards, the articulating surfaces of the atlas looking towards each other, the occiput set down betwixt them, so as to be se- cured towards either side, and the obliquity of the joint being such withal as to prevent die head from turning round. These joints ofthe occiput of the adas are, like the greater joints of the body, secured with regular capsules or bag-like ligaments for each condyle, each rising from a rough surface on the verte- bra, and being fixed into a roughness at the root of the condyle. 2. We find a flat membranous ligament, which extends from the ring of the adas to the ring of the occipital hole, closing the interstice betwixt the occiput and the adas: it is confounded at the sides with the capsules of the articulating processes ; is very strong before ; and at the middle short point of the adas it seems a distinct ligament, which is strong only at this point, and very lax and membranous behind.* 3. We find the atlas tied to the dentatus by a more complete order of ligaments.— These are, 1st, (as betwixt the atlas and dentatus,) regular cap- sules or bags, fixing the condyles of one vertebra to the condyles of the other. 2dly, A cross ligament,! which, crossing the ring ofthe first vertebra, makes a bridge, embraces the neck of the tooth-like process, and ties it down in its place. 3dly, A smooth and cartilaginous surface all round the root ofthe tooth- like process, where this tooth of the dentatus turns in the ring of the atlas, and is bound by the ligament; and this rolling of the adas upon the axis of the dentatus is so fair and proper a joint, that it also is all included in a capsular ligament. 4thly, The point of the tooth-like process having threaded the ring of the atlas, almost touches the occipital hole ; and there another ligament ties it by its point to the occipital hole.i: All the other vertebrae have another kind of articulation ; to which the occiput, atlas, and dentatus, are the only exceptions; for their motions are particular, and quite different from the This is part of what Winslow called ligamentum infundibuliforme, a rvNNEL-LiKE ugament, joining the first vertebra to the occiput. t Viz. Ligamentum transversals, or transversum; and what are call- ed the appendices ofthe transverse ligament, are merely its edges exten- ding upwards and downwards, to be fixed into the dentatus, and into the occipi- ™h2|f» w as " inclose the tooth-like process of the dentatus in a capsule. iii" are two flat 1'gaments which come from about the neck or root of the tooth-Like process, and which go obliquely upwards, to be fixed into the groove just behind the hp of the occipital hole; but the ligament from the point of'the tooth- like Process is not what it has been supposed, a fair round ligament of some strength; there is nothing more than a few straggling fibres of ligament going 'torn rhe point to throcrip(.r. though Fustachius has drawn i; round and strong. 260 JOINTS OF THE HEAD AND SPINE. rest. The atlas and dentatus bend, turn, and roll, by con- nections resembling the common joints of the body ; but the other vertebra are united, each by its intervertebral sub- stance, to the bones above and below ; they are also united by their articulating processes to each other : each articulating process is held to another by a distinct capsule ; each inter- vertebral substance is secured, bound down, and strengthened by strong ligaments ; for the intervertebral substance, which of itself adheres very strongly to the periosteum, and to the rough socket-like surface upon the body of each vertebra, is further secured by a sort of cross ligaments, which go from the rim or edge of one vertebra to the edge of the next, over the intervertebral substance ; and so, by adhering to the inter- vertebral substance, they strengthen it. These ligaments cross each other over the interstice betwixt each vertebra, and are very strong. They are very regular, beautiful, and shin- ing, and are named intervertebral ligaments. The spine is further secured by a general ligamentous or tendinous expansion, which goes over the fore parts of all the vertebra from top to bottom of the spine. It begins at the fore part ofthe atlas ; it almost passes the body of the dentatus, or is but very slightly attached to it. It is at first pointed, small, and round ; it begins to expand upon the third vertebra of the neck, so as to cover almost all its body. It goes down along the bones, chiefly on their fore parts, and is but little ob- served on their sides. It is weaker in the neck, where there is much motion; stronger in the back, where there is none; weaker again in the loins, where the vertebrae move ; but still on the bodies of all the vertebrae it is seen white, shining, and tendinous. We can distinguish all along the spine interrup- tions and fasciculi, or firmer bundles, going from piece to piece of the spine ; which fasciculi are indeed very seldom continued without interruption farther than the length of two or three vertebrae ; yet the whole is so much continued, that it is considered as one uninterrupted sheath, and is called the external or anterior vagina, or ligament ofthe spine*. But still the canal of the spine were left open and undefend- ed, rough and dangerous to the spinal marrow, if internal ligaments were not added to these. The rings of the vertebrae are held at a considerable distance from each other, by the thickness of the intervertebral substance, and by the corres- * The ligamentum commune anterius, fascia lonoitudinalis an- terior, fascia ligamentosa, &c. It is from this ligament in the loins that the crura diaphragmatis arise, with tendons flat and glistening like the ligament itself, and hardly to be distinguished from it. JOINTS OF THE HEAD AND SPINE. 261 ponding length of the oblique processes : but this space is fil- led up by a strong flat ligament, which goes from the edge of one ring to the edge of another ; and so extending from the articulating processes, backwards to the spinous processes, they fill up all the interstice, complete the canal of the spinal marrow, and bind the bones together with great strength*: these are assisted in their office of holding the vertebrae to- gether, by a continuation of the same ligament, or of a liga- mentous ihembrane connected with it, which runs all the way onwards to the ends of the spinous processes, where they are strengthened by accidental fasciculif ; and in the middle verte- brae of the back, but not of those of the loins or neck, similar ligaments are found also betwixt the transverse processes:}:. Next, there is another internal ligament, which is not inter- rupted from bone to bone, but runs along all the length of the spine, within the medullary canal, and it corresponds so with the external vagina, or anterior ligament of the spine, that it is called the posterior or internal ligament^. It begins at the occiput, lies flat upon the back part of the bodies of the vertebrae ; at the interstice of every vertebra it spreads out broad upon the intervertebral substance, doing the same office within, that the intervertebral ligaments do without. It is broader above ; it grows gradually narrower towards the loins. Although it is called a vagina or sheath, it does by no means surround nor inclose the spinal marrow, but is entirely con- fined to the covering of the bodies of the vertebrae, never go- ing beyond the setting off the articulating surfaces, or the place where the nerves go out. It adheres firmly to the bones, and does not belong at all to the spinal marrow. It should rather be called a ligament for the bones than a sheath for the medulla. The anterior ligament prevents straining of the spine backwards : this one prevents the bending of the spine too much forwards ; and they inclose betwixt them the bodies of the vertebras and their intervertebral substances. There is yet a third internal ligament, which belongs entireh, to the neck ;'itis called apparatus ligamentosus colli; RUM. •They are named the ligamenta suuflava crurum teocessuum snsoso- t These are named the membrane interspinales, and ligamenta apices .pinarum comitantes. The ligaments which tie the points of the s,>ines, run- ning from point to point, make a long ligament, which stretches down all thc spine. fhl fif?,, .k GAMuNTA !'rocess™m transversorim, and found only from the fifth to the tenth vertebra of the back. * «r»!ALC,AUOAMENT°SAPOmcA' rASC,A ™*r.ni-oi: M.n rorncA, liga- mentum COMMUNE POSTFKIUS. 262 JOIMTS OP THE HEAD AND SPINE. it begins from the edge of the occipital bone, descends in the canal of the vertebra;, is thin and flat, and adheres firmly to the body of each vertebra, covering the tooth-like process. The irregular fasciculi, or bundles of this ligament, stretch from bone to bone ; and the whole of the apparatus ligamento. sus extends from the edge of the occipital hole to the fourth vertebra of the neck, where it ends. Its chief use is also as a ligament, merely fixing the head to the neck. The dura mater is within these, immediately inclosing the spinal marrow. The ligaments which I have just named may be well enough allowed to be " at once ligaments for the bones, and a sheath for the medulla." But there is no such sheath as that called ligamentum infundibuliforme by Winslow ; for either they aw peculiar and distinct ligaments for the bones, such as I have described, or they belong exclusively to the medulla, as the dura mater, which is indeed strengthened at certain points into the thickness of a ligament; but the only close connection of the spinal marrow with the ligaments ofthe spine is just at the hole of the occipital bone, and for a little way down ; through all the rest of the spine, the connection is by the loosest cellular substance. OF THE LOWER JAW. The lower jaw is, by its natural form, almost a strict hinge, and the lateral motion in grinding is but very slight The joint is formed by a deep hollow or socket in the temporal bone ; by a ridge, which stands just before the proper socket, at the root of the zygomatic process ; and by a long small head or condyle, which is placed across the long branch or condyloid process of the jaw. These form the joint; and the condyle, the hollow of the temporal bone, and the root of the zygomatic process, are all covered with articulating carti- lage. The joint is completed by a capsule of the common form, which arises from the neck of the condyle, and which is so fixed into the temporal bone as to include both the proper socket and the root of the zygomatic process. Thence it is manifest, that in the motions of the jaw, this transverse ridge is required as a part of its articulating surface ; that the com- mon and lesser motions are performed by the condyle moving in the deepest part of its socket; that the larger and wider openings of the mouth are performed by such depression of the jaw as makes its condyle mount upon the root ofthe zygomatic process ; while the luxation of the jaw is a starting forwards of the condyle, till it is lodged quite before and under the JOINTS OP THE HEAD AND SPINE. 26G zygomatic process, and the condyle standing upon the highest ridge, is the dangerous position in which luxation is most easi- ly produced. To render these motions very easy and free, a moveable car- tilage is interposed. We find such cartilages in the joints of the clavicle, wrist, knee, and jaw, because the motions are continual and rapid. The moveable cartilage is thin in its centre, and thicker towards its edges, by which it rather deep- ens than fills up the hollow ofthe joint. It corresponds in shape with the head or condyle of the jaw, and with the hol- low of the temporal bone. It moves with every motion ot the jair, facilitates the common motions, and prevents luxa- tion ; but the joint is still more strongly secured by the strength of its pterygoid and temporal muscles, which are in- serted close round the joint, than by any strength of its capsule. It is the muscles which prevent luxation ; and it is their action also that makes luxation, when it has happened, so difficult to reduce. RIBS. The ribs have two joints, and a hinge-like motion, rising and falling alternately as we draw in or let out the breath. The two joints ofthe ribs are thus secured: First, the proper head ofthe ribs being hinged upon the intervertebral substance, and touching two vertebrae, it is tied to the bodies of each by a regular capsule : the bag is regular, is lubricated within, and is as perfect as any joint in the body ; it is radiated without, so as to expand pretty broad upon the sides of the vertebrae, and has a sort of division as if into two fasciculi; the one belonging to the vertebra above, the other to the -vertebra below: they gradually vanish, and mix with the periosteum upon the bo- dies of the vertebra; these are named ligamentum capi- telli costarum, as belonging to the little heads ofthe ribs. The back of the rib touches the fore part of the transverse process, and is articulated there ; consequently there is a small capsular ligament belonging to this joint also : but this joint is further secured by two small ligaments, which come from the transverse process ofthe vertebra, and take hold on the neck of the rib: one short ligament coming from the point ofthe trans- verse process, is behind the rib, and is thence named liga- mentum transversarium externum : another, rather lon- ger comes from the inner face ofthe transverse process, goes a little round the neck of the rib, is implanted into the lower edge of the rib, andis*named ligamentum transversarium 264 joints of the internum : another small ligament exactly opposite to this, going into the neck of the rib upon its back part, is also very regular; and other subsidiary ligaments from different points assist these or supply their place. The ribs are fixed into the sternum by their cartilages; each of which has a round head, a distinct socket, a regular capsule, and ligaments which expand upon the surface ofthe sternum, much in the same way that the ligamenta capitelli expand up- on the bodies of the vertebrae : a tendinous membrane also binds the cartilages of the ribs one to another, crosses over the interstice, and so covers the intercostal muscles with a sort of fascia ; and the whole surface of the sternum and that of the cartilages is covered with this tendinous expansion, which be- longs confusedly to the origins of the pectoral muscles, to the ligaments of the ribs and sternum, and to the periosteum of that bone. ----•&•---- CHAP. II. JOINTS OF THE SHOULDER, ARM, AND HAND. clavicle. X HE joining of the clavicle with the sternum is the hinge up- on which the whole arm moves, and is the only point by which the arm is connected with the trunk : the round button-like "head of the clavicle rolls upon the articulating surface of the upper bone of the sternum : it is in such continual motion that some particular provision is required ; and accordingly it has, like the condyle of the jaw, a small moving cartilage, which rolls betwixt this head and the sternum. The cartilage is thin, and of a mucous nature ; it is moveable in some degree, yet it is fixed by one edge to the head of the clavicle. This joint is inclosed in a strong capsule ; consisting first of a bag, and then of an outer order of fibres, which go out in a radiated form, up- on the surface of the sternum, like the ligaments of the ribs ; and they cross and cover the sternum, so that the ligaments of the opposite sides meet; and this meeting forms a cord across the upper part of the sternum, which is named interclavicu- lar ligament. Thus is the clavicle fixed to the sternum. and another broad ligament also ties it to the first rib. SHOULDER, ARM, AND HAND. 265 The joining of the clavicle with the scapula is by the edge ofthe flat clavicle touching the edge ofthe acromion processes with a narrow but flat articulating surface. Both surfaces, viz. of the acromion and of die clavicle, are covered with a thin ar- ticulating cartilage : in some subjects a moveable cartilage is also found here. It is a regular joint, and is very seldom obli- terated ; yet its motion, though continual, is not very free ; it is rather a shuffling and bending of the scapula upon this bone, favouring the play of the other joints. It is secured first by a capsular ligament, which is in itself delicate and thin, but which is strengthened by many ligamentous bands, which pass (over the capsule) betwixt the clavicle and the acromion process : the clavicle, as it passes over the point of the coracoid process, is tied down to it by a ligament of considerable strength, which comes from the point of the coracoid process, is implanted into the lower or inner edge of the clavicle, and is named liga- mentum commune trapezoides ; trapezoid, on account of its square form, and commune, because it goes from the scapula to the clavicle ; while other ligaments, going from one process of the scapula to another, are named proper or peculiar liga- ments ofthe scapula. There is a small slip of ligament which joins this, coming from the tendon of the subclavian muscle. SHOULDER-JOINT. The shoulder is one ofthe most beautiful joints, loose and moveable, very free in its motions, but very liable to be dis- placed. To form this joint, the humerus has a large round and flattened head ; the cavity of the scapula,* which receives this head, is oval or triangular, small and very shallow : it is eked out with a thick cartilaginous border, which increases the hol- low of the socket; but still it is so shallow that the humerus cannot be so much said to be lodged in die glenoid cavity, as to be laid upon it. Its capsule or bag is very loose and wide, coming from the edges of the glenoid cavity, and implanted round the neck of the bone. The joint is richly bedewed with mucus ; or rather with a mixed secretion, which is partly se- creted by a fimbriated organ, consisting of lacunae or bags, the common organ for this secretion through all the joints, and by a thinner exudation from those extreme arteries, which ter- minate, with open mouths, upon the internal surface of the bag. • It is called glenoid cavity from the Greek name of a joint, and the name is no* absolutely appropriated to the scapula. Vol. I. 2 L 26b JOINTS of the By the shallowness of its socket, and the largeness of its head; by the looseness of its capsule ; by all the forms and circumstances of its structure ;—the shoulder is exceedingly loose, and very liable to be displaced: it has this loose structure and superficial socket, that its motions may be free ; but sel- dom is there any great advantage gained in the human body without a counterbalance of weakness and danger ; and every where in the limbs we observe that a joint is weak and liable to luxation in proportion as its motions are free and large. Yet the shoulder-joint is not without some kind of defence; its socket is shallow, but it is guarded by the largest projecting process in all the body ; by the acromion projecting and strengthening it above ; and by the coracoid process within; its ligament is lax, easily torn, and useful rather for confining the synovia, and keeping the head of the shoulder-bone oppo- site to its proper cavity, than in securing the joint by any strength it has ; therefore a ligament extends from the coracoid 10 the acromion process,* which completes the defences ofthe joint above, and at its inner side ; and there comes also from the point of the acromion process an additional ligament which adheres to the capsule : but the circumstance from which the chief strength ofthe shoulder-joint .is derived, is the insertion of the four muscles which come from the shoulder-blade close round the head of the bone ; so that they adhere to the capsular ligament, pull it up to prevent its being checked in the motions of the joint; strengthen it by their thickness, for they are spread upon it: and the contraction of the muscles holds the humerus in its place ; their total relaxation (as in certain cases of weakness) suffers the humerus to drop away from the scapu- la, without any fall or accident, forming what we are accustom- ed to call a luxation of the humerus from an internal cause; and the shoulder cannot be luxated by a fall without such vio- lence as tears up these muscles by the roots. We must add to ihis anatomy of the joint, that it is surrounded by numbers of bursae or mucous bags :f one under the tendons ofthe subsca- pularis ; one under the short head of the biceps muscles ; one betwixt the coracoid process and the shoulder-bone ; and one under the acromion process of the scapula, exceedingly large: and.these are so fairly parts of the joint, that very commonly '■ Ligamentum i-roprium triangulare scapulae. ■(■ Vide Monro's Tables of the Bursa: Mucosae, where all these parts are repre- sented ; the knowledge of which is so very useful for the surgeon. I have opened this great bursa under the acromion process, and let out four pounds of the pecu- liar mucus and gelatinous lumps with which the. diseased bursa: are commnnlr filled. SHOULDER, ARM, AND HAND. 267 they open into it with communications, either perfectly natural or at least not hurtful, either originally existing or formed by continual friction. It should also be remembered, that the long tendinous head ofthe biceps muscle comes from the margin of the socket, directly over the ball of the os humeri, and through the capsule, by a particular hole. ELBOW. The elbow-joint is formed by three bones ; the humerus, radius, and ulna: the Ulna bends backwards and forwards up- on the shoulder-bone ; the radius bends upon the shoulder- bone along with the ulna; it always must accompany the ulna, but it also has a motion of its own, rolling in circles ; its round button-like head rolling continually with its edge upon a socket in the ulna, and with its flat face upon the tubercle ofthe hume- rus. The whole composes one joint, and is inclosed in one capsule : the bones accompany each other in their luxations, as well as in their natural motions : the ulna is never dislocated without the radius being also displaced ; a circumstance which is but too little noticed, and, so far as I remember, hardly con- sidered or known. The general capsule arises from the hu- merus, from both the tubercles, and all round the two hollows which receive the olecranon and coronoid processes of the ul- na ; it is implanted again into the tip of the olecranon, and all round that sigmoid cavity which receives the lower end of the humerus, and all round the edge of the coronary process. It is also fixed round the neck of the radius ; it comprehends, in one bag, the humerus, radius, and ulna; and unites them into one joint, performing two motions, viz. flexion and extension by the ulna, and rolling by the radius* The joint is lubricated by mucus and by fat, which is found chiefly about the olecra- non ; and that the bones may be further secured, additional ligaments are spread out upon them, which are all without the common capsule of the joint lying upon it, and strengthening it at the necessary points. 1. There is the common capsule inclosing the whole. 2. It is the form of every hinge-joint (and this is one ofthe purest) to have its capsule strengthened at the sides ; and the sides of this, the elbow-joint, are strengthened by two fasciculi or liga- mentous heads, which, coming from the tubercles of the hume- rus, spread a little upon the capsule, and adhere to it like part of its substance. One, from the outer condyle, spreads upon the neck ofthe radius, and is named the external later at ligament : one from the inner con J vie of thc hunerus, goes 268 joints of the upon the inside of the capsule, and strengthens it there : it is implanted near the root of the coronoid process ofthe ulna, and is named the internal lateral ligament. 3. The conti- nual rolling motion of the radius requires a peculiar ligamen t; and this peculiar ligament ofthe radius is named ligamentum coronarium, because it encircles the neck of the radius; annulare or orbiculare, from its hoop or ring-like form. It is a very strong and narrow stripe or band, which arises from that part of the ulna where the radius rolls upon it, and sur- rounds the radius, making at least two-thirds of a circle ; and so having turned over the neck of the radius, is inserted into the opposite side of the ulna. This is commonly described as a distinct ligament surrounding the neck of the radius, and having the common capsule implanted into its upper edge ; but in truth it is, like the others, a thicker band of the common cap- sule, but with a distinction much more particular here, by the contrast of the great thickness of the coronary ligament, and the extreme thinness of the capsule at the fore part: for the capsule of every hinge-joint is strong only at its sides ; other bands from the outer condyle, and from the coronary process of the ulna, strengthen this ligament of the radius, and are known by the general name of accessory ligaments of the coronoid ligament, as the lateral ones are known by the name of accessory ligaments to the capsule. So that there is, 1. A complete capsule which encloses all the bones ; 2. Lateral ligaments which make the main strength of the joint; 3. A coronary ligament which regulates and strength- ens the rolling motions of the radius, and keeps it firm, turning like a spindle in its bush. The whole joint is surrounded with cellular substance ; the regularity of its ligaments is confound- ed by the adhesions of muscles and tendons : though it is, on the whole, weak behind and before, and very strong at its sides, yet tendinous and ligamentous fibres cross it in all directions; so that the capsule, and its assisting ligaments, are irregular and rough without; but gelatinous, smooth, and glossy within. WRIST. The wrist is one ofthe most moveable joints in the body, having the strength of a mere hinge-joint (because it is almost a strict hinge, by the connection of the long ball of the carpus with the long hollow of the radius ;) and having, at the same time, all the properties of the most moveable joint, by the free turning of the radius, without the weak ess which is peculiar SHOULDER, ARM, AND HAND. 269 vo the circular and free moving joints. These distinctions di- vide the wrist-joint into its two parts. 1. The articulation formed by the scaphoid and lunated bones, which form an oval ball of articulation, and the great scaphoid cavity of the radius which receives this ball. The end of the ulna does not properly enter into the cavity of the wrist, but its end, or little round head, is covered with a move- able cartilage, and that cartilage represents the end of the ulna. Now this firsj joint, viz. ofthe scaphoid and lunated bones, the head of the radius, and the moveable cartilage which repre- sents the head of the ulna, are surrounded by the general cap- sule or bag of the joint. The capsule arises from the ends of the radius and of the ulna ; from the styloid point of the one round to the same point ofthe other; and is implanted near the lower rank of the carpal bones. Though it adheres first to the scaphoid and lunated bones, it passes them, going over all thc bones of the carpus, especially in the palm, so as to add strength to their peculiar ligaments ; and in the palm, the tendons for the fingers run over it: so it forms on one side an additional ligament for the carpus; on the other, it forms the floor of the tendinous sheath, a smooth and lubricated surface for the ten- dons to run upon. This general ligament is strengthened by particular ones coming from the styloid processes of the radius and of the ulna. But there are so many irregular points of bone about the wrist, that the little fasciculi, with which this capsule is covered and strengthened, are innumerable. Within this joint, and stretching from the groove betwixt the scaphoid and lunated bones, there is an internal ligament of a soft and pulpy nature ; it is named ligamentum mucosum : but the very name shows that it is less valuable as a ligament (since the joint is already well enough secured,) than as a conductor for the lacunae or ducts which separate the mucus. 2. The articulation by which the hand performs all its turn- ing motions is that of the radius with the ulna : this is set apart altogether from the general articulation of the joint. The la- teral cavity of the radius receives the little round head of the ulna ; they are enclosed in their own peculiar capsule ; which is so loose about the bones, that although it is a regular cap- sule ofthe common form, it has the name of membrana cap- sularis sacciformis. Thus there is one joint within another ; a moveable cartilage betwixt them, and the capsule of one, the more moveable joint, peculiarly wide, and not so strong ; all which should be considered in thinking about luxations of the wrist. The carpal bones are connected with each- other so very closely, that the name of joint can hardly be used. They are 270. JOINTS of the rather fixed than jointed together. Each bone has four smooth articulating surfaces, by which it is united to the adjoining bones. The, first two bones form the great ball of the wrist; the second row again is united with the first by a sort of ball and socket; for the os magnum, which is the central bone of the second row, has a large round head, which is received into the lunated hollow of the os lunare, which is the central bone of the first row. The first row is thus united to the second by a distinct and general capsule; in addition to which each single bone is tied to the next adjoining, by a regular capsular ligament within, and by flat cross ligaments without, or rather by many bundles of ligaments, which cross each other in a very complicated manner; and the little flat and shining fasciculi give the whole a radiated or star-like form*. The metacarpal bones are also joined to the carpal in one row, by aline of joints which are as one joint; besides their common capsule, the metacarpal of each finger has its peculiar ligaments proceeding in a radiated or star-like form from the carpal bones, and going out broad upon the metacarpal bones; and so numerous, that each metacarpal bone is securely tied by ligaments to one or two of the bones of the carpus f; and at their heads, where the fingers are implanted upon them, forming the knuckles, they are again tied by flat ligaments, which go from head to head of the metacarpal bones:}:, binding them together, permitting a slight bending towards each other, so as to make a hollow in the hand, but no such wide motion as might assist the fingers ; they are but as a foundation upon which the fingers stand and move. FINGERS. The joints of the fingers are formed by round heads in the upper end of one row of bones, and by hollow sockets on the lower ends of the next row. Each joint is qualified by the round form of its head to be a circular and free moving joint; but it is restricted by the forms of its ligaments to the nature ot a hinge-joint; for each finger-joint is included first in a fair round capsule or bag, of the ordinary form ; but that capsule * These are the ligaments which are really so unimportant to the anatomist or to the surgeon, but which are so laboriously described under the titles of liga- menta BREVIA, OBLIQJJA TR ANSVERS ARIA, and PROPRIA OSSIOM CARPI j for they do in fact cross and traverse the carpus in every possible direction. f And these also are named, according to their several directions, ligamenta articularia, lateralia, recta, p'erpendichlaria, &c. \ These are named the ligamenta interossea. SHOULDER, ARM, AND HAND. 271 is strengthened by very distinct lateral ligaments upon its sides, which lateral ligaments form the chief strength of the joints ; above these lateral ligaments the joint is strengthened by a broad fascia or sheath, which comes from the tendons of the interossei muscles, covers the backs of all the fingers, and which is especially strong over the joints. One part of the apparatus of the wrist-joint is the smooth and lubricated sheath, in which the tendons of the fingers run. It is formed in part by the outer side of the capsule of the wrist, and in part by that bridge of ligament which proceeds from the four corner points of the carpal bones. This sheath is lined with a delicate and softer modification of the common tendin- ous membrane ; is fully bedewed with mucus ; and is fairly to be ranked with the bursae mucosae, as it is indeed, like them, a shut sack. But it is farther crossed in such a manner by parti- tions belonging to each flexor tendon, that each of them may be said to have its appropriated bursa mucosa. And these bursae, to prevent the bad consequence s of friction, are put both betwixt the cross ligament and the tendons, and also be- twixt the tendons of the uppermost muscle and of the deeper one, and again betwixt the tendons of the fingers and of the thumb. In the same way the sheaths of the tendons, as they run along the fingers, may be considered as part of the apparatus of their joints ; for the first set of bursae, viz. those which lie in the palm of the hand, stop before they reach the first joints of the fingers, and then other longitudinal bursae begin from. the first joint of the fingers, and go all along them to the last joint; forming a sheath for the tendons to run in, which does at once the office of a strong ligament, binding them down in their places, and which is so lubricated on its internal surface as to save the necessity of other bursas. These sheaths are thicker in certain points, so as to form cross rings of strong ligament; but the common sheath and these thicker rings still form one continual canal: these are named the sheaths and annular ligaments, or cross ligaments*, of the fingers, and are of the same nature with the bursae. Besides these, there are no distinct bursae on the fingers, but there are several about the wrist, and one especially of a considerable size at the root of the thumbf. * Ligamenta vaginalia, ligamenta cruciata phalangum, &r. f Vide Monro's Bursse Mucosae. ( 272 ) CHAP. III. JOINTS OF THE THIGH, LEG, AND ANKLE. OF THE HIP-JOINT. A HE acetabulum, which is rough in the naked bone, is na- turally lined with a thick and very smoofli cartilage. The head of the thigh-bone is covered with a similar cartilage, also very thick and smooth ; and these cartilages almost fill up that deep dimple which is seen in the centre of the head of the thigh-bone, and smooth that hole which is formed in the centre of the socket, by the meeting of the several pieces of which it is composed. The socket is not only deep in its bones, but is further deepened by the cartilage which tips the edge-of the socket, and which stands up to a considerable height. The socket is imperfect at that side which looks towards the thyroid hole ; the bony edge is entirely wanting there, and the space is filled up by a strong cartilaginous ligament which goes across this gap, from the one point to the other, and from its going across is named the ligamentum labri cartilagin^i transversale*. The capsular ligament of the hip-joint is the thickest and strongest of all the body. It is, like other capsules, a reflection and thickening of the periosteum ; the periosteum coming along the outside of the bone, leaves it at the edge of the socket. The periosteum, or rather perichon- drium from the inside of the socket, comes up to the edge, and meets the outer layer. They unite together, so as to form the general capsule, inclosing the ring-like cartilage, which tips the edge of the socket between them. This ligament in- closes all the bones from the edges of the socket to the roots of the trochanters, embracing not only the head but the neck of the thigh-bone. The outer plate, continuous with the pe- riosteum, is thick and strong, and is assisted by much cellular substance condensed round it, and it is further thickened by slips which come from the iliacus, glutaeus, and other muscles which pass over the joint, while the external plate of the liga- ment lines the whole with a soft and well lubricated coat. * This ligament is double; that is, there is one on the inside of the edge, and one on the outside ; thence it is often reckoned as two ligaments, viz. ligamen- tum transversale internum et externum. THIGH, LEO, AND ANKLE. ,273 In addition to this general capsule, there are two internal ligaments, 1st, The round ligament, as it is called, which comes from the centre of the socket to be fixed into the centre of the ball of the thigh-bone. It is not round, but flat or triangular. It has a broad triangular basis, rooted in the socket exactly at that place where the several bones of the socket meet, forming a triangular ridge, which gives this triangular form to the central ligament. It has three angles, and three flat sides. It is broad where it arises from the bot- tom of the socket, is about an inch and a half in length, grows narrower as it goes outwards towards the head of the bone, and is almost roiLad where it is implanted into the dimple in the head of die thigh-bone; at which point it is so fixed as to leave a very remarkable roughness in the naked bone. But round the roots of this ligament, and in the bottom of the socket, there is left a pretty deep hollow, which is said to be filled up with the synovial gland. It is wonderful how easily authors talk of the synovial gland, as if they had seen it; they describe very formally its affections and diseases, as when hurt by a blow upon the trochanter; yet there is no distinct gland to be found. There is a fringed and ragged mass lodged in the bottom of the socket, hanging out into the hollow, and con- tinually rubbed by the ball of the thigh-bone in its motions : the fringes and points certainly are ducts from which we can squeeze out mucus; but it is by no means proved that they belong to a synovial gland; and it looks rather as if the ducts were themselves the secreting organ, like the lacunae or mucous bags in the tongue, or in the urethra vagina, oesophagus, and other hollow tubes. Such a structure is fitter for suffering the strong pressure and continual action ofthe thigh-bone than any determined gland. We see then nothing but mucous ducts of a fringed form, hanging down from this hollow into the cavity of the joint; a quantity of fat accompanying these fringes ; and a pappy mucous membrane, which keeps these fringes and fatty membranes orderly and in their places, and which ties them so to the angles of the triangular ligament, that they must move with the motions of the joint. This mucous membrane, which keeps these fatty fringes orderlv, has two or three small bridles in different directions ; whence they are named the ligamenta mucosa,or ligamentula massae adiposas glandulosa; and this may be considered as the continued in- flection of the softer internal lamella of the capsule, which not only lines the socket, but is reflected over the central ligament, and over the globe of the thigh-bone, covering them also with a delicate mucous coat. Other fringes of the same kind are found at the lower part of the joint, lying round the neck ot Vol. I. 2 M S/4 Joints or the the thigh-bone, near the angle where the capsular ligament is implanted into the root ofthe great trochanter: the liquor from these mucous fimbriae, with the general serous exudations, are mixed and blended for lubricating the joint. This capsule, which is naturally the thickest and strongest in the body, almost a quarter of an inch in thickness, is farther strengthened by many additions: for a slip of very strong ten- dinous or cellular substance condensed comes down from the lower spinous process of the os ilium, and spreads out over the capsule, and strengthens it very much on its fore part; the smallest of the glutppi muscles adheres to the capsule and strengthens it behind ; the psoas magnus and Uiaijus internus pass by the inner side of the capsule ; and though they do not absolutely adhere to it, they deposit much cellular substance, which is condensed so as to strengthen the capsule, forming at the same time a large bursa mucosa betwixt their tendinous fibres and the joint. That tendon of the rectus muscle which comes from the margin of the socket, lies upon the outer side of the capsule, adheres to it, and strengthens it. The security ofthe hip-joint seems to depend more upon the strength of its capsular ligament than that of almost any other joint. THE KNEE-JOINT. The knee-joint is one ofthe most superficial joints and one of the weakest, so far as relates to the bones ; for the flat con- dyles ofthe thigh-bone are merely laid upon the flat head ofthe tibia. There is here no fair cavity receiving a large head, as in the joint of the hip ; no slighter ball and socket, as in the fin- gers ; no strong overhanging bones, as in the shoulder; no hook-like process, as in the ulna. This is not a hinge-joint, like the ankle, secured between two points of bone. We do not find the means of strength in its bones, but in the number, size, and disposition of the great ligaments with which its bones are joined; by virtue of these ligaments it is the strongest joint of the human body, the most oppressed by great loads, the most exercised in continual motions, yet less frequently displaced than any other. But this complication of ligaments, which gives it mechanical strength, is the very cause of its consti- tutional weakness ; makes it very delicate ; and very liable to disease. The bones which compose this joint are the tibia, thigh-bone, and patella; and they are united by many ligaments, both widiin and without the joint. 1st, The capsule of the knee is naturally very th'm and THIGH, leg, and ankle. 275 delicate,transparent as a cobweb. This thin capsule comes from the fore part of the thigh-bone, all round the articulating surfaces, whence it goes downwards by the sides of the con- dyles; from this origin it is inserted into all the edge ofthe ro- tula, and in such a way as to keep the rotula properly without the cavity of the joint; the capsular ligament going over its in- ner surface, and lining it with a smooth and delicate coat. It is fixed below into all the circle of the head of the tibia, and thus completes its circle, embracing all the bones. This cap- sule, naturally so thin and delicate, is made up from all the sur- rounding parts to a considerable thickness ; first, it is covered behind by the h«««ls ct the gastrocnemii; at the sides by the biceps and other muscles of the hamstrings ; on its fore part, it is strengthened by die general fascia of the thigh, which goes down over the knee, and being there reinforced both by its ad- hesion to the bones and by the broad expansion of the vastus internus, sartorius, biceps, and other muscles which go out over the patella, it adheres to the capsule, and makes the whole very strong; besides which, there is a ligament which, lying in the ham, upon the back part of the capsule, is named, in com- pliment to Winslow, ligamentum posticum wtnslowii. It is a ligament somewhat resembling the lateral ligaments ofthe elbow. It ari-es from the outer condyle, goes obliquely across- the back part of the joint, adheres to it, and strengthens it; but often it is not found at all, or in such straggling fibres as cannot be accounted as a ligament. It is manifest that the knee re- quires some such additional ligaments behind to serve as a check, and to prevent its yielding too far. 2. The knee, as being a hinge-joint, has its stronger liga- ments at the sides; and although we speak of lateral ligaments in the other joints, this is the only one where the lateral liga- ments are very distinct from the common capside of the joint; on the inner side of the joint there comes down from the inter- nal condyle of the thigh-bone a broad flat ligament, which is fixed into the inner head ofthe tibia, and is named the internal lateral ligament; on the outside of the knee there descends from the tip ofthe outer condyle a much stronger ligament, not quite so flat, nther round: it extends from the condyle of the thigh-bone to the bump of the fibula, which it embraces. It is a little conical from above downwards; it is from two to three inches in length, and is named ligamentum latf.rale ex- ternum longus, to distinguish it from the next: for behind this first external ligament there arises, a litde lower from the same condyle, along with the outer head of the gastrocnemius muscle, a ligament which is called the ligamentum late- rale externum brevius ; and it is not shorter only, but so 276 JOINTS of the scattered as not to be easily distinguished, not having the true form of a lateral ligament coming down from the condyle, but of a mere strengthening of the capsule, coming upwards from the knob of the fibula. 3. The joint is still further secured by internal ligaments, which are within the cavity of the joint; they are named the crucial ligaments of the knee. They arise betwixt the hol- low of the condyles ofthe thigh-bone, and are implanted into the back part of the middle rising of the tibia: they lie in the back part of the joint, flat upon the back of the capsule ; and the one crossing a little hrfart* the other (but yet in contact with each other at the place of crossing,) they are cuatiaguished by the names of anterior and posterior crucial ligamx.wts. The posterior crucial ligament is more perpendicular; it arises from the hollow betwixt the condyles ofthe thigh-bone, and is implanted into a roughness on the back of the tibia, be- twixt its two cup-like hollows, and behind the tubercle which divides these hollows from each other. While the posterior arises rather from the internal condyle, the anterior liga- ment arises properly from the external condyle, passes oblique- ly over the tuber in the articulating surface of the tibia, and terminates in the cup-like hollow. The effect of these two li- gaments is more particular than is commonly observed ; for the one goes obliquely out over the articulating surface of the tibia, while the other goes directly down behind the joint; and of course when the knee is bended, the posterior ligament is extended ; when the leg is stretched out, the anterior ligament is extended: they both are checks upon the motions of the joint: the anterior ligament prevents the leg going too far for- wards ; the posterior ligament prevents its being too much bent back upon the thigh. 4. The most admirable part ofthe mechanism of this joint is the two semilunar cartilages. They are so named from their semilunar form ; they lie upon the top of the tibia, so as to fill up, each of them, one of the hollows on the top of that bone. They are thicker towards their convex edges, thinner towards their concave edges ; the}*- end by two very acute and long horns, named the cornua of the lunated cartilages. In short, they resemble the shape of the label which we put round a wine decanter ; and the two horns are tied to the tubercle or ridge that stands in the middle of the articular surface of the tibia; and consequendy they are turned towards each other so as to touch in their points. There are here, as in the other joints, masses of fat inclosing the fimbriated ends of the mu- cous ducts. These fimbriae and fatty bundles are formed chief- ly round the circumference ofthe patella, commonly surround- THIGH, LEG, AND ANKLE. 277 ing it with a complete fringe ; they are also found at the back of the cavity, about the crucial ligaments, and in all the inter- stices of the joint; the fatty bundles filling up the interstices, protecting the mucous ducts from more violence than what is just necessary to empty them, and perhaps mixing their exuda- tion with the mucus of the ducts. These masses of fat lie covered by the delicate internal sur- face ofthe capsule, and the mucous fimbriae project from it. The inner surface of the capsule is so much larger than the joint which it lines, that it makes many folds or lurks ; and several of these are distinguished by particular names. Thus at each side ofdie patella there are two such folds, the one lar- ger than the other; whence they are named ligamentum alare majus, and ligamentum alare minus. These two folds are like two legs, which join and form one middle fold, which runs across in the very centre of the joint, viz. from the lower end of the patella to the point of the thigh-bone, in the middle betwixt the condyles. It keeps the looser fatty bundles and fimbriated ducts in their place (viz. the hollow betwixt the condyles, where they are least exposed to harm;) thence it has been long named the ligamentum mucosum.—* The internal membrane of the joint covers also the semilunar ligaments as a perichondrium ; it comes off from the ridge of the tibia, touches the horns of the semilunar cartilages, moves over the cartilage so as to give them their coat; and at the point where it first touches the horns, it forms four litde liga- ments, two for the horns of each cartilage. These tags, by which the four points of the lunated cartilages are tied, are named the ligamenta cartilaginum lunatarum, or more simply named the four adhesions of the lunated cartilages. There is a little slip of ligament which goes round upon the fore part of the knob of the tibia, and ties the fore parts of these two cartilages to each other. It is named ligamentum transversale commune, because it goes across from the fore edge of the one cartilage to the fore edge ofthe other, .and be- cause it belongs equally to each ; but for their further security, these cartilages also adhere to their outer circle or thick edge, to the internal surface of the general capsule of the joint, and that again adheres to the lateral ligaments which are without it; so that there is every security for these cartilages being firm enough in their places to bear the motions of the joint, and yet loose enough to follow them easily. This joint has the largest bursae mucosae of all, and these perhaps the most frequently diseased. There is one bursa above the patella, betwixt the common tendon of the extensor muscles and the fore part of the thigh-bone, which is no less 278 JOINTS OF THE than three inches in length. There is a smaller bursa about au inch below the patella, and under the ligament of the patella, protecting it from friction, upon the head of the tibia. These bursae, I am persuaded, are often the seat of disease, when it is judged to be in the joint itself. But the truth is very easily known ; for if a swelling appear under the patella, projecting at the sides, and raising the patella from the other bones, we are sure that it must be in the main cavity of the joint: but if swellings appear above and below the patella, then there is rea- son to believe that these belong to the great bursas, which are placed above and below ti:nt for itself; but is strengthened by the external lateralligament of the knee, whichadheres to this knob, and by the insertion of the biceps tendon, which i& im- planted into this point, and which spreads its expanded tendon over the fore part of the tibia, and holds the bones together; and the firmness of the fibula is further secured by the great interosseous ligament, which goes from bone to bone. ANKLE. The ankle-joint owes less of its strength to ligaments than to the particular forms of its bones ; for while the strong lateral ligaments of the knee guard it so that it cannot be dislocated till they are torn, the lower heads of the tibia and fibula so guard the foot that it cannot be luxated sidewise with- out such violence as breaks these bones : first, the fibula is so connected with the tibia at its lower end, that they form to- gether one cavity for receiving the astragalus, with two pro- jecting points ; the fibula forming the outer ankle, and the tibia forming the process of the inner ankle ; the joining of the fibula to the tibia here, is like that of its upper end, too close to admit of the smallest motion ; and it is thoroughly ( secured by particular ligaments ; one of which passing from the fibula to the tibia on the fore part, is named the ligamen- tum superius anticum, consisting in general of one or two distinct flat bands. Another more continued and broader li- gamentous membrane goes from the fibula to the tibia across the back part, and is named ligamentum posticum superi- us ; the ligamentum ^osticum inferius being but a slip of the same. Next comes the capsule of the joint, which joins the astragalus to the lower heads ofthe tibia and the fibula; it is thinner both before and behind than we should expect from the strength of a joint which bears all the weight and the most violent motions of the body. But, in fact, the capsule every- where serves other purposes than giving strength to the joint, THIGH, LEG, AND ANKLE. 281 and never is strong except by additional ligaments from with- out ; so it is with the ankle-joint, the capsule of which is ex- ceedingly thin before, but it is strengthened at the back part, and especially at the sides, by supplementary ligaments : first, a strong ligament comes down from the acute point of the in- ner ankle, expands in a radiated form upon the general cap- sule ; adheres to it, and strengthens it, and is fixed all along the sides of the astragalus: this ligament coming from one point, and expanding to be inserted into a long line, has a tri- angular form, whence it is named ligamentum deltoides; and while the general ligament secures the joint towards that side, the oblique fibres of its fore edge prevent the foot being too much extended, as in leaping ; and its oblique fibres on the back edge prevent its being too much bended, as in climbing ; but the ligaments of the outer ankle, tying it to the other side of the astragalus, are indeed distinct, one going forwards, one going backwards, and one running directly downwards ; one goes from the point or knob of the fibula, obliquely down- wards and forwards, to be inserted into the side of the astra- galus : it is square and flat, of considerable breadth and strength, and is called ligamentum fibulae anterius. Another ligament goes perpendicularly downwards, from the acute point of the outer ankle, to spread upon the side of the astragalus and of the capsule, and is finally inserted into the heel-bone ; this is named the ligamentum fibula perpen- diculare. A third ligament goes out still from the same point, to go backwards over the back part of the capsule; ad- heres to the back ofthe capsule, and strengthens it, and is named ligamentum inter fibulam et astragalum, posterius. There is nothing very particularly worthy of notice in the ankle- joint ; for it is covered with cartilages ; lined with a soft and mucous membrane; and lubricated with mucous fimbriae and masses of fat, such as are found in all the joints. It is stronger than the other joints ; it can hardly be luxated without a lacer- ation of its ligaments, and breaking of the bones which guard it at either side ; and it is the great violence which is required for completing this dislocation, and the terrible complication of dislocation, fracture, and laceration of the skin, which makes this accident so dangerous beyond any other luxation. The astragalus, os calcis, os naviculare, and all the bones ofthe tarsus, are united to each other by large heads and distinct and peculiar joints ; besides which, the bones are cross tied to one another by ligaments so numerous and complicated that they cannot nor need not be explained. They pass across from bone to bone in an infinite variety of directions ; some longitudinal; some transverse ; and some oblique. There is Vol. I. 2 N 282 JOINTS OT THE a curious complication, which may we call a web of ligaments, covering either side of the foot with shining and star-like bun- dles : each bone has its capsular ligament for joining it to the next; each joint of each bone has its articulating cartilages al- ways fresh and lubricated ; each joint has, besides its capsule, flat strips of oblique, longitudinal, and transverse ligaments,' 1| joining it to the nearest bones : and the greater bones have lar- ger and more important ligaments, as from the astragalus to the os calcis, from the bs calcis to the os naviculare, and from that again to the scaphoid bone, &c. The matatarsal bones have their capsular ligaments joining them to the tarsal bones, and they have ligaments strengthen- ing their capsules, and tying them more strongly to the tarsal bones ; and, as in the metacarpal bones, the several ranks are tied one to another by cross ligaments, which pass from the root of one bone to the root of the next. We have ligaments of the same description and use, holding the metatarsal bones to- gether, both on the upper and on the lower surface of the foot; and all the ligaments ofthe foot are of great strength and thick- ness. The lower ends of the metatarsal bones have also trans- verse ligaments by which they are tied to each other. The toes have hinge-joints, formed by capsules, and secured by lateral ligaments, as those of the fingers are; and except in the strength or number of ligaments, the joinings of the carpus, metacarpus, and fingers, exactly resemble the joinings of the tarsus, meta- tarsus, and toes. But these ligaments, though helping to join the individual bones, could not have much effect in supporting the whole arch of the foot. It is further secured by a great ligament, which extends in one triangular and flat plate from the point of the heel to the roots of each toe. This is named the aponeurosis plantaris pedis ; which is not merely an aponeurosis for co- vering, defending, and supporting, the muscles of the foot; that might have been done on easier terms with a fascia, very slight compared with this ; but the chief use ofthe plantar apo- neurosis is to support the arch of the foot. It passes from point to point, like the bow-string betwixt the two horns of a bow, and, after leaping or hard walking, it is m the sole ofthe foot that we feel the straining and pain : so that, like the pal- mar aponeurosis, it supports the arch, gives origin to the short muscles of the toes, braces them in their action, and makes bridges under which the long tendons are allowed to pass ; it comes off from the heel in one point; it grows broader in the same proportion as the sole of the foot grows broad ; it is di- vided into three narrow heads, which make forks, and are in- serted into the roots of the second, third, and fourth toes ; and THIGH, LEG, AND ANKLE. 283 the great toe and the little toe have two smaller or lateral apo- neuroses, which cover their own particular muscLs, and are implanted into the roots of the great toe and of the little toe. The bursae mucosae surround the ankle and foot in great numbers. None of them having any very direct connection with the joint, and most of them accompanying the long ten- dons as they pass behind the ankle, or in the sole of the foot, are of that kind which we call tendinous sheaths. First, There are sheaths of two or three inches long, which surround the ten- dons ofthe tibialis posticus, and of thc peronaei muscles, as they pass down behind the ankle. The sheaths of the peronaei be- gin from that point where the tendons first begin to rub against the bone, and are continued quite down into the sole of the foot; making first a common sheath for both tendons, and then a bursa peculiar to the tendons of the peronaeus brevis muscle, and about an inch in length. Where the peronaeus longus begins to pass under the sole of the foot, the sheath which inclosed it behind the ankle is shut, and a new bursa begins ; in the same manner, where the tendons of the flexor pollicis and flexor digi- torum pedis pass behind the inner ankle, a bursa of three in- ches in length surrounds them and facilitates the motion. As the tendons of the flexor muscles go under the arch of the foot, they lie among soft parts, and rub chiefly against the flesh of the massa carnea and the belly of the short flexor muscles : but whenever they touch the first joints of their toes, they once. more rub against a hard bone. New bursae are formed for the tendons. Each bursa is a distinct bag, running along the flat face of the toe, and is of a long shape, and the tendon is carried through the centre of the lubricated bag ; so that we see once more that there is no true distinction betwixt bursae mucosae and tendinous sheaths, nor betwixt the tendinous sheaths and the capsuh s of joints. Joints have been arranged under various forms, but not with much success ; and I do not know that enumerating the joints in any particular order will either explain the motions of indi- vidual joints, or assist in recording their various forms ; some joints are loose and free, capable of easy motions, but weak in proportion, andliable to be displaced ; such is the joint of the shoulder, which rolls in every direction : other rolling j oints, more limited in their motions, are better secured with ligaments of peculiar strength ; such is the joint of the hip, where the ligaments are of great strength both within and without: some, wanting all circular motions, are hinge-joints by the mere form of dieir bones ; such are the lower jaw, the vertebra, the elbow, and the ankle-joints : some are hinges by their liga- ments, which are then disposed only along the sides of the 284 JOINTS OF THE, &C bones ; such are the knee, the ribs, the fingers, and the toes. Some joints partake of either motion with all the free- dom of a ball and a socket-joint, yet with the strength and secu- rity ofthe strictest hinge : thus the wrist, having one joint by which its turning motions are performed, and another joint by which it rolls, has the two great endowments so rarely combin- ed in any joint of the freest motion, and of great strength; so also has the head, by the combination of two joints of opposite uses and forms ; for its own condyles play like a mere hinge upon the atlas ; and the axis of the dentatus secures all the properties of a circular joint: this combination gives it all the motions of either joint without their peculiar defects. But there is still a third order of joints, which have such an obscure and shuffling motion that it cannot be observed. The carpus and metacarpus, the tarsus and metatarsus, the tibia with the fibula, have these shuffling and almost immoveable joints; they are not intended for much motion among them- selves, but are appointed by a diffused and gradual yielding to facilitate the motions of other joints. L\D OF THE FIRST VOLUME. T'HE ANATOMY OF THE HUMAN BODY. IN FOUR VOLUMES, ILLUSTRATED WITH ONE HUNDRED AND TWENTY-FIVE ENGRAVINGS* VOLUME II. CONTAINING THE ANATOMY OF THE HEART AND ARTERIES. By JOHN "BELL, Surgeon. FROM THE THIRD LONDON EDITION, IMPROVED BT THE AUTHOR. NEW-YORK: PRINTED AND SOLD BY COLLINS AND PERKINS, NO. 189, PEARL-STREET. 1809. DR. JAMES JEFFRAY, PROFESSOR OF ANATOMY IN THE UNIVERSITY of glasgow. Dear Sir, W hen this volume first appeared, you mentioned to me some doubts concerning the office which I had ascribed to the Eustachian valve. You proposed to publish some criti- cal observations, on this part of my Book, and, with a libe- rality becoming our common profession, and your high station in it, you spoke of addressing those strictures to myself. It is no small gratification to me, that I have it now in my power to present a new Edition of this Volume, imperfect as it is, to one who allows it some merit, while he is yet not in- sensible to its defects. I believe you will accept with pleasure this slight testimony of respect and esteem, from one who can have no motive but respect and esteem for professing himself in this particular manner, Your most faithful and obedient Humble Servant, JOHN BELL. PREFACE. —«*■ JL his volume consists of two parts ; the Anatomy and Phy- siology of the Heart—the Arrangements and Descriptions of all the Arteries ofthe body. The discovery of the circulation of the blood has been always regarded as one of the most important, and has been ranked rather with the great doctrines of philosophy, than with the little discoveries in our peculiar science ; it has been boasted of by our countrymen, and much coveted, and often claimed, by strangers. The discovery is most ingenious and beautiful, and is the foundation of all that physicians have thought or practised, right or wrong, useful or destructive, ever since. How the well-proved doctrines of Harvey were perverted ; what new, strange, monstrous, and impossible circles his an- tagonists contrived for the blood, it were tedious to relate ; but it is most natural to mention why his doctrines were op- posed. It was the universal opinion in those days, that the blood was formed in the liver, and sent out from it by all the Veins to nourish the body, proceeding outwards during the day, and returning by night. The old physicians had thus entered into a train of thinking which it was not easy to change : these notions about the blood were become great and impor- tant doctrines, and had descended to them from their oldest VI .PREFACE. teachers, with many weighty dependencies, conclusions, and rules of practice issuing from them : they were as articles of faith which it was a heresy to forsake ; and it was easy to fore- see, that should the Harveian doctrine prevail; should it be once completely proved that the blood moved outwards along the arteries and returned only by the veins ; then all the rea- sonings of the physicians would be confounded ; their theories embracing the whole body of physic disturbed ; their system of practice entirely overthrown ; and all that they had written themselves, and all the ancient books which they had read with so much diligence (for they were really learned ;) all that they had ever been proud of ; was to be wiped out from the thoughts of that and of all succeeding ages ! But the doctrine of Harvey did at last prevail, dispelled those idle dreams of humours and temperaments, and spirits, and blood! of the blood concocted in the liver, and moving outwards along the veins to nourish the body ; of the blood moving outwards during all the day, and returning by night; of the arteries carrying air only or vital spirits, to animate the system by mixing with the blood, while the veins alone convey- ed the proper blood. Yet this theory ofthe illustrious Harvey introduced general doctrines more mischievous in all their con- sequences than those which had just vanished : as, that the blood was composed of particular globules, the larger globules of smaller ones, and these again of globules of a third series ; and that the arteries were so proportioned to the diameters of those globules, and descended by steps so regular and uniform, that each kind of artery had its peculiar globule which it re- ceived with ease, while others were rejected ; or, if unhappily driven by a too violent action into vessels which they did not suit, were arrested in their progress ; and produced either some local inflammation or some universal disease. These are the once famous doctrines of Malpighi, Boerhaave, and all the great men of their day ; and which they dilated into various forms, and adorned with the fine words of lentor, remora, error loci. To these succeeded the mechanical physicians, who, by tur- PREFACE. VU intelligible problems of mathematics and algebra (reasonings which were ill-founded in their principles, even had the calcu- lations been correct,) pretended to estimate the force of the heart, the velocity of the blood, the power of the arteries, the strength ofthe veins, and the shape and size of each secreting orifice, according to the secretion which it had to perform. These were the doctrines, these the discoveries,, which ren- dered famous the names of Bellini, Pitcairn, Keil, Hales, and other mechanical physicians, whose books are gone " to the vault of all the Capulets." The chemists next soon turned their thoughts, from the vain search after the universal solvent and the philosopher's stone, to pharmacy and the useful arts. By the abilities and industry of Newman, this branch began to assume the more respecta- ble appearance of a useful art ; it began to be allied to science, and its connection with medicine was found to be ofthe most direct and important nature. Having analysed the materials of the druggist, the chemists proceeded to analyse the parts of the human body to which those medicines were to be applied: but from this rational com- mencement followed one of the most trivial of all the miserable doctrines with which our science has been disgraced ; for as the chemists had already explained the properties of the salts, metals, earths, and of all active substances, by the angles, cubes, or other forms which they saw their particles assume, they soon persuaded themselves that such forms as cubes, wedges, spiculae, &c. existed in the blood ; and acid and alka- line humours, sharp, corrosive, irritating, and pointed particles, were the terms in which they expressed their most admired theories; and acids, alkalis, and metals, and medicines for rounding the pointed particles, or obtunding (as they termed it,) or sheathing, or covering the acrimonious humours, were their chief preventatives and cures. Until the present day, this fault has pervaded all the great theories, that in describing our vessels physicians have con- tinued to use the language of hydraulics and hydrostatics; of a philosophy applicable only to rigid tubes : in short, in Vll PREFACE. describing the living system, they have forgotten that it was endowed with life. We also may have erred in our turn: but with whatever de- gree of contempt we may view the doctrines of these older au- thors ; or however succeeding generations may be amused with ours—still this is plain, that the most important facts in all anatomy, and the chief doctrines of the human body, must always accompany the explanation of those two great functions of the heart and lungs. Of course the constitution of the blood ; the chemistry of airs ; our dependence, so incessant and immediate, upon the atmosphere in which we live ; the various and singular ways by which the foetuses of different creatures, or the creatures themselves, according to their pecu- liar modes of life, draw their existence from the atmosphere; the various kinds of circulation by which this air is distributed through the system of each; the effects of air particularly upon our body ; and the effects also of accidents, deformities, and diseases in those prime organs—all this wide circle of phy- siology belongs, in the strictest and clearest sense, to the anato- my of the heart. For one chief purpose in studying the anato- my of the human body is to understand its functions, and to compare them with those of other creatures, till we arrive at last at some distant conception of the whole ; of the various structures of animals and vegetables ; and of the various func- tions which in each of these classes support life, and action, and through it the principle of life. There is no occasion on which this desire of knowledge, this willing admiration of the wonders of nature, is so strong as on first studying the functions of the lungs and heart ; for upon the conjoined offices of the heart and lungs all perfect life seems to depend. And how universal these two functions are ; how necessary to the support of the greater animals ; how essential also to the constitution of the meanest insect—it shall be my business to explain. The knowledge of the arteries again bears along with it the whole anatomy of the human body. The nerves accompany the arteries, the lymphatics and veins twine round them ; the PREFACE. ix glands and various organs are composed of them. The inti- mate structure of parts is known only by understanding the forms of their vessels; and as each individual part is nourish- ed by arteries, he who has studied the arteries thoroughly, knows the whole. But to the surgeon the knowledge of the arterial system is valuable beyond all calculation or belief. He performs no operation in which arteries are not engaged ; he cures no great wound in which arteries are not first to be tied; he en- ters into no consultation in which the arteries are not first spo- ken of. Without a knowledge of the arteries he can neither think sensibly nor act safely. Most unhappily all this comes to be known only at that pe- riod of life when the deepest conviction can produce only fear and perplexity, sorrow and regret. Yet, strange to tell, there is no such conviction; no regret, no irresolution, no perplexity, is ever seen! A surgeon, as ignorantof the blood-vessels as of every other point of anatomy, shall proceed in his operations with a for- wardness and boldness terrible to those who know the danger ; yet with a success and good fortune exceeding all belief. The causes of all this are very plain. A relaxation in the discipline of the schools is the first cause—an indifference to anatomy, so marked and pointed, that an anatomical thesis in this country was never known. Every young man especially fears the difficulty of this part of anatomy, and shuns it. He is not duly impressed with such a high sense of its impor- tance as to make labour pleasant; and when he is advanced to practice, he takes comfort daily from the mistakes and igno- rance of others. A slender consolation! to see exemplified in others the faults and dangers to which we ourselves are ex- posed. If these negligencies may stand excused on any account, it is on this only, that anatomists have been accustomed to write, not for the Public, in plain and simple language, but for each other, in an unknown tongue. By this I mean not a foreign or a dead language, but a peculiar style and phrase which no one can understand unless he be initiated ; unless he have sttL- b \ PREFACE. died the science itself so intensely, that he has also learned the jargon in which it is conveyed: in short, no one but a thorough anatomist can understand the language of anatomy, nor can even he understand it without some labour. Anatomists have have buried their science under the rubbish of names; there is not a difficult or hard sounding word upon which they have any claim, that they have not retained: they have choked their subject with useless minutiae, they have polluted their language, by transferring to it from Latin many words which, by their continual inflections in that language, were beautiful, while their unvaried, uncouth termination in ours, is barbarous in the utterance, while it tends but to interrupt and puzzle the sense : " They have impressed into the service of their science a great many poor words that would get their habeas corpus from any court in Christendom." An anatomist, for example, will describe an artery as " go- ing to the radial edge of the second metacarpal bone; then supplying the abductor and flexor muscles -, then going along the bone of the first phalanx, seated upon this second metacar- pal bone," with many other distortions, ambiguities, and little contrivances, to conceal (as one would believe) that he is describing so simple a matter as the artery of the fore-finger; which the reader at last finds out either by some lucky chance, or by reflecting how many metacarpal bones there are ; and then reckoning them first forwards and then backwards, that he may be sure which it is that the author means ; for his author may count from the litde finger towards the thumb, or from the thumb towards the little finger, or he may have a fancy of leaving out the thumb, and reckoning only four. What must be the surprise of any well-educated young man when he reads in those books which he must study, of the regions of the elbow or thumb, or fore-finger ? And if an anatomist understands such things with difficulty, how dis- tressing must they be to the student ? This is the scholastic jargon which has so long been the pride of anatomists and the disgrace of their science; which has given young men a dislike for the most useful of all their PREFACE. *1 studies; and which it is now full time to banish from our schools. These are the authors who avoid plainness as if it were meanness; who are studious of hard words as if they constituted the perfection of science : " it is their trade, it is their mystery, to write obscurely;" and full sorely does the student feel it. Want of arrangement, again, has still worse effects. Con- fusion is a monster in science ; and Thomson has, in his Man of the Moon, described such a thing with great spirit and life : " A creature, if that may be called a creature which had no shape nor form, next rolled towards him, approaching Still nearer and nearer, and by various glances and movements seemed to indicate a sympathy with man ;«it was a rpde un- formed mass ; legs and arms, fingers and toes, and membranes, and glands, and entrails and teeth, were blended into one abominable mass." If I should tell my reader tftat there are very nearly one thousand arteries in the body, going prom^fCjy^ously to bones, ligaments, bowels, and glands, muscles, and nerves, to a thousand unconnected difficult parts, all of which he must know by name, how would lie be affected f But when I ob- serve, that these go to the neck, the head, the arm, the leg, he begins to see this confusion of muscles, and glands, an4 bowels, vanish, and to perceive that all these arteries may be usefully and very simply arranged. When he is next taught to know the course of each greater artery, and the parts in which each division and branch of it lies, he perceives clearly that the parts through which it runs, as the arm-pit, neck, of groin, must limit and regulate the number of its branches, and give to each twig even an appropriate place and name : When next the whole arterial system is marked and chalked out for him in different portions ; when there are points of pe- culiar importance set apart which he is charged to learn with particular care—-he sees a good end in all this toil; he begins with courage, and gets forward easily ; it becomes an interest- ing, and of course a pleasing, task. But still it is a task : and I entmit the young student, as he values his own honour, or XU , PREFACE. the safety of his friends, not to bate himself one iota of the whole. Let him not take an indolent advantage of those ar- rangements, which are meant to promote his industry, not to prevent it. Let him not read only concerning the greater arteries, neglecting the smaller ones, but go through the whole piece of anatomy honestly and fairly. He will no doubt for- get in time the smaller arteries ; but by having studied even them with diligence, he must remember the great and im- portant arteries with a clearness of comprehension and ar- rangement, which those who have not gone thus honestly , through the whole study can never attain. Let him also re- member, that studies like these, well performed during his early years, do, like past dangers, or the remembrance of good deeds, give an ease and pleasure to his after-life. The arteries, I will now venture to say, should be with the surgeon as familiar as his name ; and there is no argument which proves it more strongly than this, that a man of real learning, of sterling good-sense, of a clear head and steady hand, a man accomplished in all other respects, and fitted by nature and genius for performing the most difficult operations, if yet he want this part of knowledge, may, in one unhappy moment, do things which he must think of with horror during all his life. I know well how little such accidents are thought of, when at last the evil day comes. A surgeon hardly be- lieves this strict knowledge of the arteries to be so great a point. In the midst of an operation, or in a common wound, it gives him no concern to see arteries bleed which he did not look for; nor has he great reluctance to drive his needle among parts which he does not know. An art<;:*y bleeds, and he looks for it; he calls out at last to screw the tourniquet, and it stops ; the tourniquet is loosened again, and again it bleeds; again the screw is tightened on account of the loss of blood; he expects to strike the artery; he is accustomed to strike it, not by know ing where it lies, but by seeing it bleed : at last some lucky dab of the needle succeeds, or perhaps from faint- ness of the patient the bleeding ceases: the surgeon is relieved from his present anxiety ; but in a few hours he is called back PRFFACE. sift to this scene of confusion and dismay: yet at last the bleeding in somehow or other mastered ; and thus he gets on through all his difficulties, accident after accident, operation after operation, till at last he almost forgets that anatomy was a branch of his education, or the knowledge of blood-vessels necessary in operations or wounds. I will not say that a man cannot suppress a bleeding from a wound in the arm, because he is not acquainted with the anatomy of the arm ; but this surely I may be allowed to say, that it is a piece of knowledge which at all times, but especial- ly in those circumstances, can do no harm; and that if you leave a patient to choose betwixt two surgeons, one skilled in the knowledge of arteries, another knowing them only by seeing them spout out blood, it is easy to foretel where his choice will fall. Perhaps some will be so hardened as to say, " and yet we seldom hear that patients die of bleeding." Is it then a merit that your patient is not plainly killed; that he does not expire under your hands ? Is it nothing to lose blood from day to day ? Is it nothing that your patient is reduced to extreme weakness, suffering every thing but actual death ? Is it nothing that he lies with tourniquets round the limbs in fear and anxiety, attended by young surgeons appointed to watch that bleeding, which may burst out while the patient turns in bed, and destroy him in one moment ? Is it nothing to have fresh incisions and new searchings for the artery to endure ?—These are real difficulties and dangers, and they should be provided for; our honour as well as our duty requires it. Bleeding from a great artery is to the patient the greatest danger: the very report of an ill accident is to the surgeon (though, God knows, he may be blameless) the greatest disgrace; and, lastly, though it should not be so, his taking up a bleeding artery dexterously and quickly, when others have failed, is a great honour. When we think of all the important consequences of being thoroughly versed in this part of anatomy, they crowd upon Our imagination more in number than can be even named. xiv PREFACE. The surgeon may, indeed, provide for the arteries to be cut in a regular operation, by consulting books ; but when he is cal- led to a patient bleeding and faint, perhaps expiring, that per- son must live or die by his immediate skill! By his skill he will obtain the good opinion, not of ignorant attendants only, but of the profession: and by a bold and sensible conduct in any difficult situation he may give them a lesson of real use. Let us but for a moment think ofthe chances of those wounded in war;—the alarming, unthought-of accidents which over- take us daily in private life ;—the wounds and hurts which workmen receive :—let us reflect on all the kinds of aneurism both in the heart and arteries, from wounds, from blows, from inward diseases :—let us think of all the various operations in which arteries are concerned—and then declare whether, of all his studies, the young man should not value that most which makes him so immediately and eminently useful. COLLINS & PERKINS Will speedily publish, in one large Volume, 8vo.—Illustrated with numerous Engravings—Price 5 dollars, AN ABRIDGMENT OF JOHN BELVS PRINCIPLES OF SURGERY, ORIGINALLY IN THREE VOLS. 4TO. By JOHN AUGUSTINE SMITH, Ofthe Royal College of Surgeons, London, and Professor of Ahah> my and Surgery in the University of New-York. ALSO :— In Two Volumes, 8vo.—price 6 dollars, « A Treatise on Febrile Diseases, including Intermitting, Remit- ting, and Continued Fevers, Eruptive Fevers, Inflammations, He- morrhages, and the Profluvia ; in which an attempt is made to pre- sent, at one view, whatever, in the present state of medicine, it is requisite for the Physician to know respecting the symptoms, causes and cure of those dieases. TO WHICH IS ADDED, An Essay on the Nature of Fever, being an attempt to ascertain the Principles of its Treatment." By A. P. WILSON, M. D. he. &c. N. B. The English Edition of this valuable work is in 5 vols. 8vo. and sells at Eighteen Dollars. Just Published^ In one handsome volume 8vo. price 2 dollars, the three popular works, entitled, " The Anatomy of the Gravid Uterus, with Practical Inferen- ces relative to Pregnancy and Labour." " Observations on Abortion, containing an account ofthe manner in which it takes place, the causes which produce it, and the method of preventing or treating it." <; Observations on Uterine Hemorrhage, with remarks on (he management of the Placenta.'' By JOHN BURNS, Lecturer on Midwifery, Glasgow. N. B. The English edition of these three volumes sells at eight dollars in calf binding. ALSO :— In a handsome volume, 12mo. price 1 dollar 25 cents, " Observations on the Utility and Administration of Purgative Medicines in several diseases." Second edition, enlarged by the Author. The Latin Formula; translated by Dr. James of Philadeh phia. By JAMES HAMILTON, M. D. Senior Physician to the Royul Infirmary of Edinburgh,- &c. &c. &c. ALSO :— In a thick vol. 8vo.—price three dollars, y " Epitome of Chemistry, in three parts, intended to facilitate the acquisition of Chemical knowledge, by minu*e instructions for the performance of experiments, directions for the analysis of mineral waters, of earths and stones, of ores, of metals, and of mineral bodies in general, and instructions for applying chemical tests and reagents to various useful purposes, 4th edition, much enlarged, and illustrated with plates: to which are added, Notes by Professor Siliiman. By WILLIAM HtNuY, M. D. N. B. This valuable work is adopted as a text-book in the Col- leges at New-Haven, Princeton and Cambridge. __ CONTENTS. BOOK I. OF THE HEART. CHAP. I. Page. OF THE MECHANISM OF THE HEART. l O "F THE PARTS OF THE HEART, 7 Venae Cava, - - - ib. Right Sinus ofthe Heart, - .8 Tuberculum Loweri, - - ib. Auricle, - - - - ib. Auricular Valves, - - 10 Right Ventricle, ... jD# Pulmonic Artery, - - -11 Sigmoid Valves, - - 12 Left Auricle, - - - 13 Semilunar Valves of the Aorta, - 14 Aorta, 15 Of the Coronary Vessels, - - ? 6 Eustachian Valve, - - 19 Irritability and Action of the Heart, - 24 Posture of the Heart, - - - 29 Pericardium, - - - 50 Conclusion, .... 53 Vol. II. XV111 CONTENTS. CHAP. II. ON THE APPEARANCE AND PROPERTIES OF THE BLOOD, OF THE CHEMISTRY OF OUR FLUIDS, AND OF THE INFLUENCE WHICH AIR HAS UPON THEM. Page. History of Opinions concerning the Blood, - 41 Life ofthe Blood, - - - -47 Qualities ofthe Blood, - - - 34 Ofthe Red Globules, - - - ib. Coagulable Lymph, - - 57 Serum, - - 59 General View of the Nature of the Blood, - 61 Chemistry of the Blood, - - 62 Influence of Air upon the Blood, - 63 1. In reddening the Blood, - 70 2. In communicating its stimulant powers, - ib. 3. In communicating heat to the Body, - 71 Respiration, or the manner in which the air is admitted to act upon the Blood, - - 78 Respiration of Plants, - - - 79 CHAP. III. OF RESPIRATION, OR THE MANNER IN WHICH THE OXYDATION OF THE BLOOD IS ACCOM- PLISHED IN VARIOUS ANIMALS AND IN MAN. History of Opinions concerning the Motions ofthe Lungs, 82 Different Species of Respiration, - 83 I. By a Diaphragm, - - 84 2. Respiration of Birds, - 85 3.------------Amphibia, - 89 4. Respiration of Fishes, - - - 93 5.------------Insects, - . .98 CHAP. IV. OF THE PECULIARITIES IN THE CIRCULATION OF THE FOETUS. General View of the Peculiarities in the Anatomical Struc- ture of the Foetus, - - 105 contents. xix Page. Ductus Venosus, - * - 106 Foramen Ovale, - - - 111 Ductus Arteriosus, - - - - 114 Explanation of the Circulation ofthe Foetus, - - 115 Critique of Opinions upon this Subject, - - ib. CHAP. V. OF MALCONFORM ATIONS OF THE HEART, AND OTHER CAUSES PREVENTING THE DUE OXY- DATION OF THE BLOOD, - - - 124 Of Malconformations of the Heart and Arteries, - ib. Ofthe Effects of these Malconformations and of ill Oxyda- ted Blood, .... 129 Of Malconformation in the Lungs, or want of the Pulmonic Artery, - - - 13* Of a Heart too small for the System, - ... Of Enlargement of the Heart, - - 138 Of Polypi, ...... 141 Thickening of the Walls or Muscular Substance of the Heart, 143 Of Aneurisms of the Aorta, - - - ib. Of Nervous Palpitations of the Heart, - . 148 BOOK II. OF THE ARTERIES. ■+» General Plan of the Arteries, - 157 CHAP. I. OF THE ARTERIES OF THE HEAD. Sect. I. Of the Carotid Arteries in general, 156 General View of the Anatomy of the Carotid Artery, 159 XX CONTENTS. 'age. I. External Carotid Artery and Arrangement of its Branches, - * 181 1. Order, going forward to the Thyroid Gland,Tongue, and Face, - - - 162 Arteria Thyroidea, - - ib. Arteria Lingualis, - - - 163 Arteria Labialis, - - - 165 2. Order, going backward from the External Carotid. Pharyngea Inferior, - - - 168 Arteria Occipitalis, - - 169 Arteria Posterior Auris, - - 170 3. Order, including the Termination of the External Carotid in the Temporal and Maxillary Arte- ries, - - - - - 171 Arteria Maxillaris Interna, - - 172 Arteria Temporalis, - - - 177 Conclusion, .... 179 Sect. II. Of the Arteries ofthe Brain, Spinal Mar- row, and Eye, - - - 182 § i. Ofthe Arteries ofthe Brain, - - ib. 2. Internal Carotid, ... 187 Division of it, - - - - 189 1. Arteria Media Cerebri, - - ib. 2. Arteria Anterior Cerebri, - 190 3. Arteria Commonicans, - - 191 Vertebral Artery, - - - - 192 1. Arteria Cerebelli Posterior, - 193 2.-------------Anterior, - 194 3.------Cerebri Posterior, - - 195 § ii. Ofthe Arteries of the Spinal Marrow, 196 1. Arteria Anterior Medulla Spinalis, - ib. 2. - ' Posterior, - - 198 § iii. Arteries ofthe Eye, - - ib. 1. Order, - . .199 Arteria Lachrymalis, - - ib. 2. Order, - . , . 200 Arteria Centralis Retinae, - . ib. Arteria Ciliares, - . 201 3. Order, . - 203 Arteria Muscularis Superior, - ib. ----------------Inferior, . 204 4. Ordkr, . _ - ib. Arteria iEthmoidalis Posterior, - ib. --------■--------■ Anterior, - 205 5. Order, . . - ib. Arteria Supra-orbitalis, - . ib. Arteria Palpebrals, - . 206 ------Nasalis, - _ }Di CONTENTS. xxi Page. Arteria Frontalis, - - 207 Conclusion, - - - 208 CHAP. II. OF THE ARTERIES OF THE ARM. 210 I. Of the Subclavian Artery, - - 213 1. Arteria Mammatja Interna, - - ib. 2.------Thy rOidea Inferior, - - 216 3. ------Vertebralisi - - 217 4.------Cervicalis Profunda, - ib. 5. ------Cervicalis Superficialis, - v 218 6. ----— Intercostalis Superior, - 219 7. ------Suprascapularis, - . ib. II. Ofthe Axillary Artery, - - 221 1. Arteria Thoracica Superior, - - 222 2.---------------Longior, - ib. 3.--------■ Humeraria, - - 223 4.--------——— Alaris, - - ib. 5. ------Subscapularis, ... 224 6. ------Circumflexa Posterior, - 226 General remarks upon the Axillary Artery, 227 III. Ofthe Brachial Artery, - . 230 1. Arteria Profunda Humeri Superior, - 231 2.---------------------Inferior, - 232 3. Ramus Anastomoticus Major, - - ib. IV. Ofthe Arteries ofthe Fore-arm, viz. ofthe Radial Ulnar, and Interosseous Arteries, 233 Division of the Artery of the Fore-arm, - 237 Arteria Recurrentes, - \ - 238 1. Recurrens Radialis Anterior, - ib. 2.--------Ulnaris Anterior, - 239 3.---------------Posterior, - ib. 4. ■ Interossea, - 240 Arteria Radialis, - - - - ib. 1. Arteria Superficialis Vola, - 241 2. Arteria Dorsalis Carpi, - 242 3.-----------,— Pollicis, - 243 4.------• Radialis Indicis, - - ib. 5.------Magna Pollicis, - 244 6.------Palmaris Profunda, - - ib. Arteria Ulnaris, - - - ib. 1. Arteria Dorsalis Ulnaris, - 245 2.------Palmaris Profunda, - - 246 Arteria Interossea, - - - 247 XXll CONTENTS. CHAP. III. OF THE ARTERIES OF THE THORAX, ABDOMEN, AND PELVIS. Pagf. § I. Arteries of the thorax, - - 248 Aorta Thoracica, - - ib. 1. Arteria Bronchiales, - - 249 Arteria Bronchialis Communis, - ib. -----------------Dextra, - ib. -----------------Sinistra, - 250 -------------. ■ Inferior, - ib. 2. Arteria Oesophagea, - - ib. 3. Intercostales Inferiores, - - 251 § II. Arteries of the abdomen, - - 262 Aorta Abdominalis, - - ib. Arteria Phrenica, - - 253 Arteries of the Stomach, Liver, and Spleen, 254 Arteria Cceliaca, ' - - - - 255 1* Arteria Coronaria Ventriculi, - - ib. Its Branches, - - 256 2. Arteria Hepatica, - - 257 Its Branches, - - 258 3. Arteria Splenica, - - - 260 Its Branches, - - ib. Arteries of the Intestines, - - - 261 Mesenteric Arteries, - - ib. 1. Meseiuw. lea Superior, - 262 Colica Media, - - - ib. ."-----Dextra, - - 263 / Ilio-Colica, - - ib. 2. Mesenterica Inferior, - - 264 Arteria Colica Sinistra, - - 265 Arteria Hamorrhoidales, - 266 Arteries ofthe fixed Viscera ofthe Abdomen, ib. 1. Arteria Capsulares, - - ib. 2. ------Renales, - . ib. 3. Arteria Spermatica, - - - 267 4. Arteria Adiposa, ... 268 5. Arteria Ureterics, - - ib. 6. ----— Lumbares, ... ib. § III. Arteries of the Pelvis, - - 269 Arteria Sacra Media, - - 270 Arteria Iliaca Interna, - - - ib. Order first, of Arteries which keep within the Pelvis. - 271 CONTENTS. XX1U Page. 1. Arteria Uio-lumbalis, - • 271 2.-------Sacra Laterales, - ib. 3. ------Hypogastrica, - - 272 4.------Vesicates, - - ib. 5.------Hamorrhoidales, - 273 6.------Hamorrhoidea Media, - ib. 7. ■ Uterina, - - ib. Order second, of Arteries which go out from the Pelvis, - - 274 1. Arteria Glutaa, - - ib. 2.-------Ischiadica, - - 275 3. ------Pudica Communis, - 276 ■i."------Obturatoria, - - - 279 CHAP. IV. ARTERIES OF THE LOWER EXTREMITY. Iliaca Externa, - - - 281 General Description of this Arteiy, - - ib. Surgery of the Femoral Artery, - - 283 Branches of the Femoral Artery, - - 287 1. Above the Groin, - - ib. Arteria Epigastrica, - - ib. Arteria Circumflexa Ileum, - - 288 2. Below the Groin. - - 289 1. Arteria Profunda Femoris, - - ib. 2. ------Circumflexa Externa,' - 290 3. —---------------Interna, - 291 4. —----Perforantes, - - 292 1. Arteria Perforans Prima, ib. 2.--------------- Secunda Magna, 293 3.---------------Tertia, - ib. 4.---------------Quarta, - 294 5. Arteria Femoralis, ... 295 S. Popliteal Artery, - - 297 1. Arteria Articularis Superior Externa, ib. 2. ------.-----------------Interna, 298 3. ■------------Media ----—, ib. 4.------.----------Inferior Externa, 299 5. ——--------------------Interna, ib. 7. Arteries of the Leg and Foot, - 300 1. Arteria Tibialis Antica, - ib. ------Recurrens, - 301 ------Malleolaris Interna, - ib. ----.------------Externa, - 302 CONTENTS. Page. Arteria Tarsea ... 302 -------Metatarsea, - - 303 Dorsalis Externa Halucis, - ib. 2. Arteria Tibialis Postica, - - 304 . - Plantaris Interna, - 305 ----------------Externa, - 306 3. Arteria Peronea, - 308 ... ■ Anterior, - - 309 ■■■■-■■ ■ Posterior, ... ib. THE ANATOMY OF THE HEART AND ARTERIES. —-■•o—-— BOOK I. OF THE HEART. CHAP. I. OF THE MECHANISM OF THE HEART. 1 HE heart is placed nearly in the centre of the human body, and is itself the centre of the circulating system. The system of vessels, which it excites and moves, consists of arteries and of veins ;—the arteries act with great strength, with a pulsa- tion like that of the heart itself, and convey the blood over all the body ; the veins are in greater number, exceedingly large, pellucid almost in their coats, incapable of that energetic action with which all the functions of the arteries are performed ; they return the blood to the heart with a slow, equable, and gentle motion, and deposite at the right side a quantity of blood equal to that which is at each pulsation driven out from the left.— The heart is placed betwixt the arteries and the veins, to re- gulate and enforce their action ; to receive the blood from the veins by a slow dilatation, and to restore, by a sudden contrac- tion, that force which the blood loses in passing round the cir- cle of the body. But the heart has also another and more im- portant office to perform ; for by having two great cavities and two orders of vessels, it performs in the same instant two cir- culations, one for the lungs and one for the body ; it receives from the lungs nothing but pure blood, it delivers out to the Vol. II. A 2 OF THE HECHANISM body nothing but what is fit for its uses : and this purifying or oxydation ofthe blood, and this excitement of the arteries, are two chief points of modern physiology, which every step ofthe following demonstration will tend to explain. It will be most easy to conceive at first the idea of a more simple heart, of one circle, of one simple circulation; of one bag for receiving, and another joined to it for propelling the blood. Indeed a heart consists merely of these essential parts; a great vein, an auricle, a ventricle, and a great arte- ry : of a vein which returns the blood from all the body; of an auricle or smaller bag, which receives that blood and retains it till the action of the heart is relaxed; of a ventricle (which is the proper heart,) strong, muscular, very irritable, and easily excited, into which the auricle pours its blood; of an artery which is allied to the ventricle in strength and action, as the au- ricle is to the vein in the delicacy of its coats, and which car- ries on the blood to the extremities of the body :—and the vein and artery meeting in all the extremities of the body, like vari- ous branches of one tube, the whole is a circle, and the heart is the central power. If an animal do not breathe, its system will be what I have now described ; it will have but one vein, one auricle, one ven- tricle, one artery; it will have one simple heart: but with us, and other breathing animals, it is not so ; and I am now to de- scribe a more complex and curious circulation. For suppose this blood so essential to our existence, to have in it some prin- ciple of life, which is continually lost, that principle must be continually renewed: the heart, which fills the arterial system, must not be taken from its appointed office, nor disturbed; na- ture appoints a second heart, which belongs entirely to this most important of all functions, viz. renewing the blood ; and it may be renewed in many various ways. It might, for exam- ple, circulate in some peculiar viscus like the liver or spleen; in the fetus it does circulate in such a mass, for the placenta is a thick and fiat cake, whose office we know to be equivalent to that of the lungs, but whose structure we do not understand: in the chijck we see its blood circulating over the yolk (for the yolk is inclosed within the membranes of the unhatched chick,) and we perceive the blood redder as it returns to the heart, and plainly changed : in fish we find the blood circulated over the gills, exposed thoroughly to the water in which they swim, and thus the gills perform to them the function of lungs. But in all breathing creatures, the lungs do this office ; the lungs are, next to the heart itself, essential to life; in those who die from bleeding, we can perceive from the livor of the face, from the sobbing and struggles of die chest, from thc regular convul- OF THE HEART. 3 sive sighs of those creatures which are butchered, rather a de- sire for air than a want of blood. It is for the purpose of this second circulation that nature has appointed in every breathing creature two hearts, a heart for the lungs, and a heart for the body ; two veins, two auricles, two ventricles, and two great arteries, one the pulmonic artery, or artery of the lungs, the other the aorta, or artery of the body. But still there are other varieties which distinguish animals into creatures of cold or of warm blood ; for there are certain constitutions which do not require that the blood should be thus continually renewed. It is not because animals are am- phibious, or go into the water, that they have peculiar lungs ; for the Land Tortoise, the Newt, the Cameleon, never go into the water ; yet they have membranous lungs : nor indeed can the Amphibise, as the Seal, the Porpoise, the Sea-Lion, &c. dive longer than a man can do ; though for whole days they lie in herds basking upon the shore ; it is their peculiar consti- tution to need less than other creatures the office of the lungs. The cold-blooded animals are generally creeping animals, sluggish, languid, cold, inert, difficultly moved, and te- nacious of life to a wonderful degree. They can bear all kinds of stimuli; they can bear to have their heads, legs, bow- els, cut away ; and among other peculiarities of this constitu- tion, they can live long without air; they will rise from time to time above water, if you allow them ; they can bear again to be kept under water, if you force them : but if they can live long under water, they can also live at least as long after you have cut off their heads, or cut out their hearts. Of those cold-blooded creatures always either the heart or the arteries are peculiar ; the heart is so in many amphibise, as in the Turtle, where the heart seems to consist of three ventri- cles, but with partitions so imperfect betwixt them that they are absolutely as one : this one ventricle gives out both the great arteries ; the blood ofthe lungs and the blood of the body are both mixed in the heart; and since there are two arteries con- veying this mixed blood, if the two arteries be nearly equal in size, then it is just one half of the blood thrown out by the heart at each stroke that receives the benefit of the lungs. In many others, as the Frog, the Newt, the Toad, the peculiarity is in the arteries alone ; they have one single and beautiful heart; there is one large auricle as a reservoir for all the blood both of the body and of the lungs ; there is one neat, small, and very powerful ventricle placed below the reservoir, having strength quite sufficient for moving both the blood of the lungs and the blood of the body ; and this ventricle gives off an aorta, which soon divides into two branches, one for the body and one for the lungs; and these of course have but half the blood 4. OF THE MECHANISM of this heart exposed to the air: these also are cold-blooded animals. But all breathing creatures, such as are called animals of hot blood, have two hearts: the one heart is sending blood through the lungs while the other heart is pushing its blood over the body ; not the half only, but the whole blood which is sent by each stroke of the heart over the body must have first passed through the lungs ; no blood can reach the heart of the body which has not been sent to it through the lungs; or, in other words, the veins of the lungs, and they alone, feed the left side of the heart. Words alone will never explain any ofthe endless difficulties which concern the mechanism of the heart; but at every point, in every kind of difficulty, in explaining the form, the parts, the posture, even the coats or coverings of the heart, I shall have recourse to plans, such as cannot fail to make all this intricate mechanism be easily conceived. The most simple form of the heart, which is represented in the Plan, No. 1. has a vein marked (a,)—an auricle (b,)—a ventricle (c,)—an artery (d;)—it has no provision for purify- ing the blood ; it has no resemblance to that kind of heart which is connected with lungs ; but the blood is received by the vein, falls into the auricle, is driven by its force into the ventri- cle, by the ventricle it is thrown into the artery, and courses round all the body, till at length, reachingthe extremities ofthe veins, it passes by the veins to the auricle a second time, and so this single circle is perfect. The heart of the amphibious creature is represented in No. 2 ; it is a frog's heart: it has the most simple form, and the fewest parts ; it has the same vein, auricle, ventricle, and arte- ry ; but its great artery divides into two chief branches, of which (a)—the aorta goes to the body,—(e) the pulmonic ar- tery goes to each side of the lungs. The heart of a breathing creature is represented in No. 3. in its most intelligible form ; and the double circulation of the human body may be traced easily in the following way.—Here the heart of the lungs is set off from the heart of the body, be- ing as distinct in office as in form and parts ; on the right side is the heart ofthe lungs, on the left side is the heart of the body. —(a) Is the great vein called vena cava from its immense size ;—there is an ascending and a descending cava; the one brings the blood from the head and arms, the other brings the blood from all the lower parts of the body; they meet at (a,) and form by their dilatation there a chief part of that bag which is called the auricle,—in it they deposite all the returning blood of the body, and thus present it at the right side of the heart to Vol. [I. . J/// /// //// %'// 7/ p.t. N°3 N't A L ^Kjt^ l^rJ »r// Zr«cy .Snttf. 4> OF THE MECHANISM of this heart exposed to the air: these also are cold-blooded animals. But all breathing creatures, such as are called animals of hot blood, have two hearts: the one heart is sending blood through the lungs while the other heart is pushing its blood over the body ; not the half only, but the whole blood which is sent by each stroke of the heart over the body must have first passed through the lungs ; no blood can reach the heart of the body which has not been sent to it through the lungs; or, in other words, the veins of the lungs, and they alone, feed the left side of the heart. Words alone will never explain any ofthe endless difficulties which concern the mechanism of the heart; but at every point, in every kind of difficulty, in explaining the form, the parts, the posture, even the coats or coverings of the heart, I shall have recourse to plans, such as cannot fail to make all this intricate mechanism be easily conceived. The most simple form of the heart, which is represented in the Plan, No. 1. has a vein marked (a,)—an auricle (£,)—a ventricle (c,)—an artery (d;)—it has no provision for purify- ing the blood ; it has no resemblance to that kind of heart which is connected with lungs ; but the blood is received by the vein, falls into the auricle, is driven by its force into the ventri- cle, by the ventricle it is thrown into the artery, and courses round all the body, till at length, reachingthe extremities ofthe veins, it passes by the veins to the auricle a second time, and so this single circle is perfect. The heart of the amphibious creature is represented in No. 2 ; it is a frog's heart: it has the most simple form, and the fewest parts ; it has the same vein, auricle, ventricle, and arte- ry ; but its great artery divides into two chief branches, of which ((f)—the aorta goes to the body,—(e) the pulmonic ar- tery goes to each side of the lungs. The heart of a breathing creature is represented in No. 3. in its most intelligible form; and the double circulation of the human body may be traced easily in the following way.—Here the heart of the lungs is set off from the heart ofthe body, be- ing as distinct in office as in form and parts ; on the right side is the heart ofthe lungs, on the left side is the heart of the body. -—(a) Is the great vein called vena cava from its immense size ;—there is an ascendirjg and a descending cava; the one brings the blood from the head and arms, the other brings the blood from all the lower parts of the body; they meet at (a,) and form by their dilatation there a chief part of that bag which is called the auricle,—in it they deposite all the returning blood of the body, and thus present it at the right side of the heart to Vol. IT. . /'//! //J f>/ /// 7//V/ 7/ p./,. N°3 N°l 1ST" 2 l* . f fKm-* ,:f%id N°4_ iT-ii .^4 « * 1^ /_,„ry .W/, OP THE HEART. 5 be moved through the lungs—(b) Is the right auricle ; it is in part formed by a dilatation of these veins, but it puts on a strong and muscular nature as it approaches the heart; it is the first cavity ofthe heart, and, like all its parts, is strong and irritable ; it is filled by the returning blood ofthe Cavas ; it re- ceives, dilates, is oppressed by this great quantity of blood ; it is strongly excited to act; in its action the blood goes down in- to the ventricle or lower cavity of the heart.—(c) Is the right ventricle, thick and strong in its walls and of great muscular power; it is filled by the auricle, and is strongly stimulated both by the stroke of the auricle and by the weight and quanti- ty, and also, in some degree, by the qualities of the blood ; its action is sudden and violent, and it drives the blood through all the system of the lungs.—(d) Is the pulmonic artery.— the artery of the lungs which receives all the blood of the right side of the heart; it is filled by the stroke of the right ventri- cle, from whose cavity it arises ; it carries the blood in many branches through all the substance of the lungs ; and thus that blood which had returned imperfect and robbed of its vital qual- ity to the right auricle ofthe heart, is by this circulation through the pulmonic artery ventilated and renewed, and made fit for the uses ofthe system ; and thus the lesser circulation or the circulation of the lungs, the circulation ofthe right side of the heart is completed, and the purified blood is brought round to the left side of the heart to undergo the greater circulation or the circulation of the body. Thus it is from the extremities of this first circle that the se- cond circle begins ; it consists of like moving powers, of an au- ricle, ventricle, vein, and artery; for as the right heart re- ceives the contaminated blood of the body from the veins of the body, the left heart receives the purified blood of the lungs from the veins of the lungs.—(e) Represents the veins of the lungs, which are sometimes three, sometimes four, in number; two enter from each side of the lungs, and return the blood purified in the lungs to the left auricle ofthe heart.—(f) Is the left auricle, smaller, but more muscular and stronger than the right; it receives easily whatever quantity of blood the lungs convey to it, it is irritated, contracts, forces the mouth of the ventricle, and fills it with this purified and redder blood.— (g) Is the left ventricle, whose form is longer, its fleshy walls thicker, its cavity smaller, its power greater far than that of the right side ; this ventricle is thus small that it may be easily filled and stimulated, and thus strong that it may propel all the blood of the body.—(A) Is the aorta or great artery of the body, arising from this left ventricle, just as the pulmonic artery arises from the right: the left veutricle, by its strong an,1 6 OP THE MECHANISM sudden stroke, not only delivers itself of its own blood, but pro- pels all the blood of the body, communicates its vibratory stroke to the extremest vessels, and excites the whole ; this is the greater circle or circulation of the body, as opposed to the short- er circulation or lesser circle of the lungs. That there are strictly two hearts, is now clearly made out; they are as different in form as in office ; there are two distinct hearts, two systems of vessels, two kinds of blood, and two circulations. These two hearts might have done their offices, though placed in the opposite sides of the breast, it is in order to strengthen mutually the effect of each other that they are joined; for the fibres ofthe two hearts intermix ; they are both inclosed in one membranous capsule, viz. the pericardium ; the veins, auricles, ventricles, and arteries, correspond in time and action with each other, and harmonize in a very beautiful manner., But this, I believe, will be more easily explained by marking the succession of motions, by a suite of figures placed upon the several parts of the heart, by which the successive motions are performed. In No. 4. I have joined the right and left hearts ; both that it may be seen how the left heart locks in behind the right heart, how the right heart comes to be the anterior one, and how the aorta seems to arise from the centre of the heart while its root is covered by the great artery of the lungs ; and also that the synchronous parts, u e. the parts which beat time with each other, maybe correctly seen.—1. The cavas are receiving the blood from all parts of the body, and in the same instant the pulmonic veins are receiving blood from the lungs. 2. The right auricle is gradually filling with the contaminated blood of the body ; the left auricle, marked also with a second figure, is filling with purified blood from the*lungs. 3. The right ventricle is stimulated by its auricle, and throws its contaminated blood into the lungs ; and in the same moment, the left ventricle throws its purified blood over the body. 4. The pulmonic artery re-acts upon the blood driven into it by the heart; and in the same moment the aorta re-acts upon the blood thrown into it, and that re-action works it through all this great system of vessels from this the centre to all the ex- tremities of the body. Thus it is easy to perceive how the successive actions accom- pany each other in the opposite sides of the heart: 1. The two veins swell; 2. The two auricles are excited; 3. The two ventricles are filled with blood ; 4. The two arteries take up and continue this pulsating action of the heart. It is thus that the two hearts assist and support the actions of each other, and Vre seems almost a physical necessity for their being joined ; Vol.11. ./>/,/tt.if/Mr 7Trff>/ p. luti J, Liury Scnl/i OF THE HEART. yet on the very best authority, and after deliberate dissection, we are entitled to affirm, that the heart is found, not with its apex sharp and conical, but cleft; the two ventricles plainly distinct from each other and divided by a great space. " La- tro, quae pcenas scelerum luebat, quando exenteraretur a carni- fice, cor habuit singularis figurse, mucrone non acuto, ut fieri solet, sed bifido ; ut distincti ventriculi manifestius externa facie apparuerint, dexter nempe et sinister, interjecto magno hiatu."* OF THE PARTS OF THE HEART. As yet I have explained only the general plan of the circula- tion, without having described those curious parts which are within the cavities of the heart, and which support the actions in this beautiful harmony and perfect order, each part subordi- nate to some other part, and each action succeeding some other action with perfect correctness, often without one unsteady motion or alarming pause, during the course of a long irregu- lar life. 1. The ven,e cavjE are two in number ;f they are named venae cavae from their very great size; the one brings the blood from the upper, and the other from the lower parts ofthe body, and they are formecUof these branches : the upper vena cava (a) is properly termed the descending cava, because it car- ries the blood of the head and arms downwards to the heart: this great vein is properly a continuation of the right jugular vein, which joins with the right axillary vein, and then de- scends into the chest a great trunk ; and in the upper part of the chest it is joined at (by—by a great branch, containing the axillary and jugular veins of the left side, which in order to reach the cava, crosses the upper part ofthe chest, and lies over the carotid arteries. The lower vena cava, or cava as- cendens, brings in like manner all the blood from the belly and lower parts of the body by two great branches. One, marked (c),—is the great vein which lies in the belly along the left side of the spine, and brings the blood from the legs, the pelvis, and parts of generation, the kidneys, &c.; it is named the vena cava abdominalis, because of its lying in the ab- * Batholini Epist. p. 107. f Let the reader observe, that the whole of this description of the various parts of the heart is, as it were, an explanation of the plans No. 5. and 6.; of which the No. 5. shows thc right side of the heart, or the heart of the lungs opened : while No. 6. shows only the left heart, or the heart ofthe body opened. 8 OF THE MECHANISM domen. Another, marked (ddd,)—arises in three or four great branches from the liver ; it is named the branches of the vena cava in the liver, or the vena cava hepatica ; and these two make up the lower cava ; and the lower and the up- per cavas now join themselves at (e)—to form the right sinus of the heart. 2. The right sinus of the heart marked (e), is of con- siderable extent; it is just the gradual dilatation of the two veins forming the auricle or reservoir, which is incessantly to supply the heart; the veins grow stronger as they approach the sinus, and the sinus still stronger as it approaches the auricle or notched and pendulous part (/*), and the auricle again ap- proaches in its nature to the ventricle of the heart; for it is crossed with very strong muscular fibres, which make very- deep risings and furrows upon its inner part. To say that these veins, or the sinus which they form, are not muscular, merely because they are not red nor fleshy, is very ignorant; for the ureters, urethra, arteries, intestines, the iris, and many other parts ofthe human body, are, at the same time, perfectly muscular and perfectly pale ; and the heart of a fish is as trans- parent as a bubble of water, and yet is so irritable, that after it is brought from market, if you lay open the breast, and stimu- late the heart with any sharp point, it will renew its contrac- tions, and in some degree the circulation. 3. The tuberculum loweri should be looked for in this point, if it were not really an imagination merely of that cele- brated anatomist. The whole matter is this ; the two veins meet, not directly, but at a considerable angle within the vein, as at (g). Lower conceived a projection of the inner coats of the vein at this point much more considerable than what I have here represented. It was thought to do the office of a valve, to break the force of the descending blood, to defend from pressure that blood which is ascending from the lower cava, and to direct ,the blood of the upper cava into the right auricle of the heart. But there is no such thing; although anatomists were at one time so fond of this trivial observation, that not one of them would demonstrate the heart, without demonstrat- ing the tuberculum Loweri; whereas, if the blood of the lower cava needs any screen above it to defend it from the pressure, it is (as I shall show presently) quite of another kind ; and in the place appointed for finding this tuberculum Loweri we can find nothing but on the inside the natural angle of the two veins, and on the outside some fat cushioned up in that angle in the line (h). 4. The auricle is, as I have said, a small appendix to the great bag or sinus, and is marked (/). ft is small, semicir- of the heart. 9 cular, notched or scolloped, and somewhat like a dog's ear ; whence its name. In general, we name the whole of this bag auricle; but by this plan the names of sinus and auricle must be easily understood. The point chiefly to be noted is this, that the veins, as they approach the auricle, are thin, delicate, transparent; that where they expand into the sinus they be- come fleshy, thick, and strong; that in the auricle itself the muscular fibres at (f) are very strong, have deep sulci like those of the ventricle, cross each other so as to make a net- work ; and these strong fibres (f) are what are named the musculi pectinati auriculae. Where these muscles run, as in cords, across the auricle they are very thick and opaque ; but in the interstice of each stripe of muscular fibre, the auricle is perfectly and beautifully transparent, like the membranes of the veins ; and these stripes of muscular fibre which are laid upon this thin membrane are almost as regular as the teeth of a comb ; and thus they are named musculi pectinati. 5. The valves of the auricle are placed at the circle (i), where the auricle enters into the ventricle, and the valves are marked (&) : and how necessary these are for regulating the movements of the heart, will be easily understood by con- sidering the conditions in which the auricle and ventricle act. First, The cavas pour in a flood of blood upon the sinus and auricle, with a continual pressure ; the moment the auricle has contracted, it is full again; the pressure from behind excites it to act, and while it is acting, there is no occasion for valves to guard those veins whose blood is pressing forwards continual- ly, because they are continually full, and have behind them the whole pressure of the circulating blood. But when the auricle acts, it throws its blood into the ventricle, fills it, and stimulates it; the auricle then lies quiescent for a moment, while it is gradually filling from behind with blood ; but during this quiescent state the whole blood from the ventricle would rush back into it, were it not guarded by valves. The valves, then, which rise whenever the ventricle begins to act, are oi this kind : there is, first, a tendinous circle or hole, by which the auricle communicates with the ventricle. The opening is large enough to admit two or three fingers to pass through it; it is smooth, seems tendinous, is plainly the place of union be- twixt the auricle and ventricle, which are in the foetus (in the chick, for example) distinct bags : and from all the circle of this hole arises a membrane, thin, and apparently delicate, but really very strong; not divided into particular valves at this root or basis, but as the membrane hangs down into the ventricle, it grows thinner, and is divided into fringes. How these fringes can do the office of valves is next to be explained. Vol. IL B 10 of the mechanism The tags and fringes of this membrane are actually tied to the inside of the ventricle by many strings, which being, like the valves, of a tendinous nature, are called cord^e tendine£, Auricular Valves. or tendinous cords ; and these cords being attached to little processes projecting from the muscular substance ofthe heart, these processes are named column^ carnea, or fleshy co- lumns. Of these tyings of the valves there are three chief points ; the whole circle seems to be divided into three sharp pointed valves ; they are named valvule tricuspides, or three-pointed, or they are still sometimes called Triglochine Valves. These strings and muscles cross each other; the valve at the left part of the circle is tied obliquely to the right side of the ventricle, and so on ; so that by this crossing of their tendons the valves fall down easily when the blood goes down through them, and they rise readily and quickly when- ever the blood gets behind them. The columns carneae tie down the valves, so that when the ventricle acts the most strongly, they are the most strongly retained. 6. The ventricle ofthe right side (//) is like its auricle, larger than the same parts on the left side ; for this auricle and Auricular Valves explained. Fig. 7. shows the Auricle and Ventricle cut open, and the valve hanging in three great divisions.—^) Part of the inside of the Auricle — (£) Part of the in- side of the Ventricle—(c) The Tendinous Circle from which the membrane of the valve arises.—(////(' ( ttj/crr//t///t 'tr/ft' from tkeJfeart of a Child about 3 or4- years old. A.^i part of the 2.unffs, b.b. the JF'ericardium by which theJTeart is sus- pended, c.c the Ventricles of theHeart, d,d. tke^Aorta encircled by the Pericardium, e.e.e.e. the Subclavian and Carotid ^Arteries, g. thejrendulous part of the Ji iff ht Auricle, h..the Cava descendens by zohich the Heart is in part suspended', i.i. the Cava ascendent with ajsenciZpassed up into the Riyht\Auricle, thisj>encil is behind the Eustachian ITrlre. the-Eustachian I7i/re itself is marked k, the little 17i Ire of the Coronary I-ein which is con- nected with it is marked m . p.ts. ^laiu r/t/ie ttiJur/ittni lfa/nr N!<4 N° 1.") R,U it'l' Lrnff-Jlllpf OF THE HEART. 23 away from its contraction all effect; but to prevent this, and to make the auricle perfect, the vena cava and auricle meet so . obliquely, that the side of the cava makes a sort of wall for the auricle on that side. This wall has entirely and distinctly the reticulated structure of the auricle itself, with fleshy bands of muscular fibres in it: this wall falls loosely backwards when the auricle is quite relaxed, as, for example, when we lay it open ; and thus it has got the appearance and name with- out the uses of a valve ; but when the heart is entire, tense, and filled with blood, this valve represents truly a part of the side of the auricle : and that this part of the wall of the auri- cle should be occasionally a little higher or lower, looser or tenser, we need not be surprised. This further may be ob- served, that wherever, as in a child, this valve is very thin and delicate, the anterior part of the fossa ovalis goes round that side of the auricle particularly deep and strong. Let it also.be remembered, that in certain animals this valve is par- ticularly large and strong; now, in a creature which goes chiefly in a horizontal posture, it may strengthen and make up the walls of the auricle (the chief use which I have assigned for it in man) ; but„ surely it cannot protect the blood of thc lower cava from the weight of blood coming from above, since the body of an animal lies horizontally, and there is no such weight. The Parisian academicians describe the heart of the Castor in the following terms : " Under the vena coronaria we find the valve called nobilis (viz. the Eustachian valve), which fills the whole trunk of the vena cava, and which is so disposed that the blood may be easily carried from the liver to the heart by the vena cava, but which is hindered from descending from the heart towards the liver through the same vein*." • Eustachian Valve. No. 14. explains merely the place of the Eustachian valve, which is seen at [m.)—No. 15. explains both the place of the valve and its relation to the oval hole (?)—behind it, and to the mouth of the ventricle (n)—which lies before it. In both these plans—(a) Is the cava descendens—(b) The aorta rising behind it—(cc) The back of the auricle slit open—(d) The cava ascendens, in the mouth of which the valve is—(e) The foramen ovale—(jjf) Its two rising borders, named pillars, isthmus of Veussens, annulus ovalis, &c.—(ot) The Eustachian valve, of which thc two cornua, or sharp points, are seen in the lower plate, ter- minating in the pillars of the foramen ovale on one hand, and in the walls of the auricle on the other. The opening of the foramen ovale (t)— is behind and above the valve; the opening into the right ventricle (n)---is before and under the valve. No. 14. explains more particularly the uses of the valve. Some authors con- ceived that it directed the blood rjsMjg in the line (e)«rupwards into the oval hole ; others that it directed the columnar blood, represented by the arrow (/>)—into thc right ventricle ; others that it protected the column (0)—from the weight of the column (/>.).—I rather suppose that it completes the furicle in the direction of the dotted line (q)—and so strengthens its action. 24 OF THE ACTION Of the irritability and action of the heart. But even this curious mechanism of the heart is not more wonderful than its incessant action, which is supported by the "continual influx of stimulant blood and by its high irritability and muscular power ; for though we cannot directly trace the various courses of its muscular fibres, there is not in the human body any part in which the muscular substance is so dense and strong. In the heart there can be no direct or straight fibres; for let them go off from the basis of the heart in what direction they may, still as they belong to the one or the other ventricle, they must, by following the course and shape of that ventricle, form an oblique line. Vasalius has indeed not represented them so, he has drawn straight fibres only; because in the lat- ter end of his great work he was without human subjects, and betook himself to drawing from beasts. The fibres of the heart are all oblique, or spiral, some lying almost transverse ; they all arise from a sort of tendinous line which unites the auricle to the ventricle ; they wind spirally down the surface till the fibres of the opposite ventricles meet in the septum and in the apex of the heart. The fibres of each ventricle pass over the convex or upper surface of the heart, then over the apex, and then ascend along the flat side of the heart, which lies upon the diaphragm, till they again reach the basis of the heart. The second layer or stratum of fibres is also oblique ; yet many of the fibres run almost transversely, uniting the oblique fibres; but when we go down into the thick substance of the heart, we find its fibres all mixed, crossed, and reticulated in a most surprising manner; so that we at once perceive both that it is the strongest muscle in the body, and that the attempt to extricate its fibres is quite absurd*. Their desire of giving more correct and regular descriptions has been the cause why those who have particularly studied this point have been fatigued and disappointed ; the most sensible of them have acknowledged with Vasalius, Albinus, and Haller, that the thing could not be done; while those, again, who pretended to particular accuracy, and who have drawn the fibres of the heart, have represented to us such ex- travagant, gross, and preposterous things, as have satisfied us more than their most ingenuous acknowledgements could have done, that they also could accomplish nothing. * Thickening the walls of the heart by vinegar, strong acids, alum, or boiling the heart, have assisted us in unravelling its structure buk very little. 6f the heart. 25 There is no question that irritability is variously bestowed in various creatures, that it is variously appointed in various parts of the body, that this property rises and falls in disease and health; without hesitation we also may pronounce that the heart is in all creatures the most irritable part; it is the part first to live and the last to die ; " Pulsus et vita pari ambulant passu." When we see the punctum saliens in the chick, we know that there is life ; and when we open either the human body or the body of an animal soon after death, still the heart is irritable and contracts. In the very first days in which the heart appears in the chick, while yet its parts are not distinguished, and the punctum saliens is the only name we can give it, the heart, even in this state feels the slightest change of heat or cold ; it is roused by heat, it languishes when cold, it is excited when heated again. It is stimulated by sharp points or acids, it works under such stimuli with a violent and perturbed motion. In all creatures it survives for a long while the death of the body ; for when the creature has died, and the breathing and pulse have long ceased, and the body is cold, when the other muscles of the body are rigid, when the stomach has ceased to feel, when the bowels which preserve their contractile power the longest have ceased to roll, and they also feel stimuli no more, still the heart preserves its irritability ; it preserves it when torn from the body and laid out upon the table; heat, caustics, sharp points, excite it to move again. We know also another thing very peculiar concerning the irritability of this organ, viz. that it is more irritable on its in- ternal than on its external surface ; for if instead of cutting out the heart we leave it connected with the body, seek out (as the old anatomists were wont to do) the thoracic duct, or pierce any great vein, and blow a bubble of air into the heart, it pursues it from auricle to ventricle, and from ventricle to auricle again, till, wearied and exhausted with this alternate action, it ceases at last, but still new stimuli will renew its force. Thus it is long after apparent drowning or other suffocation before the principle of life is gone ; and long after the death of the body before the heart be dead ; and just as in this peculiar part of the system irritability is in high proportion, there are in the scale of existence certain animals endowed in a wonderful degree with this principle of life. They are chiefly the amphi- bious creatures, as they are called, needing little air, which have this power of retaining life ; no stimuli seem to exhaust them, there seems especially to be no end to the action of their heart; a Newt's or a Toad's heart beats for days after the creature dies ; a Frog, while used in experiments, is often neg- Vol. II. X> 26 OF THE ACTION lected and forgotten, its limbs mangled, and its head gone, per- haps its spinal marrow cut across, and yet for a whole night and a day its heart does not cease beating, and continues obe- dient to stimuli for a still longer time. It seems as if nothing but the loss of organization could make this irritable muscle cease to act: or rather it seems as if even some degree of de- ranged organization could be restored : breathe upon a heart which has ceased to act, and even that gentle degree of heat and moisture will restore its action. Dr. Gardiner having left a Turtle's heart neglected in a handkerchief, he found it quite dry and shrivelled, but by soaking it in tepid water its plump- ness and contractility were restored. Since then this irritable power supports itself in parts long after they are severed from the body, what doubt should we have that there is in the muscular fibre some innate contractile power or vis insita independent of nerves ? And when we talk on a subject so difficult and so abstruse, what other proof can we expect or wish for than the power of one peculiar and insu- lated muscle surviving the separation of the head and brain, the destruction of its nerves, or its total separation from that living system to which it belongs ? If the heart be the most ir- ritable muscle of the body, if all this irritability arise from the nerves, how can it be that this muscle, which is thus announced as the most dependent on its nerves, is really the most inde- pendent ? that the muscle which of all the body needs this ner- vous supply oftenest should want it the least, and should sur- vive the loss of its nerves so much longer than the other muscles of the same body ? Although the ancients knew how irritable the heart was, al- though they often opened living creatures, and saw the heart struggling to relieve itself, because it was oppressed with blood, yet they continued entirely ignorant of the cause : and why the heart should alternately contract and relax without stop or interruption, seemed to them the most inexplicable thing in nature. Hippocrates ascribed it to the innate fire that is in the heart; Sylvius said, that the old and alkaline blood in the heart mixing with the new and acid chyle, and with the pancreatic lymph, produced a ferment there : Swammerdam, Pitcairn, and Freind, thought that the heart, and every muscle which had no antagonist muscle, was moved by a less propor- tion of the vital spirit than other muscles required. Others believed that each contraction of a muscle compressed the nerves of that muscle, and each relaxation relieved it; and that this alternate compression and relief of the nerve was the cause of the alternate movements of the heart: another physician of our own country, a great mechanic and a profound scholar in OF THE HEART. 27 mathematics, and all those parts of science which have nothing to do with the philosophy of the human body, refined upon this theory most elegantly; for observing that the nerves of the heart turned round the aorta, and passed down betwixt it and the pulmonic artery, he explained the matter thus : " These great arteries, every time they are full, will compress the nerves of the heart, and so stop this nervous fluid, and every time they are emptied (a thing which he chose to take for granted, for in truth they never are emptied,) they must leave the nerves free, and let the nervous fluid pass down to move the heart." Des Cartes, who studied every thing like a right philosopher of the old breed, viz. by conjecture alone, supposed that a small quantity of blood remained in the ventricle after each stroke of the heart; which drop of blood fermented, became a sort of leaven, and operated upon the next blood that came into the heart " like vitriol upon tartar ;" so that every succes- sive drop of blood which fell into the ventricle swelled and puffed up so suddenly as to distend the heart, and then burst out by the aorta. Philosophers have been so bewitched with the desire of explaining the phenomena of the human body, but without diligence enough to study its structure, that from Aris- totle to Buffon, it is all the same, great ignorance and great presumption. But on this subject of the pulse of the heart, physicians almost surpassed the philosophers in the absurdity of their theories, till at last they were reduced to the sad dilem- ma of either giving up speaking upon this favourite subject, or of contenting themselves with saying, " that the heart beat by its facultas pulsifica, its pulsative faculty ;" as if they had said, the jaws chew by their mandicative faculty, and the bladder pisses by its expulsive faculty, and the womb expels children by its parturient power. The ancients, I have said, often opened living creatures, and saw the heart struggling to relieve itself because it was oppress- ed with blood : this blood is itself the stimulus which moves the whole ; for important as this function is, it is equally sim- ple with all the others : and as urine is the stimulus to the blad- der, food an excitement to the intestines, and the full grown foetus a stimulus to the womb !—so is blood the true stimulus to the heart. When the blood rushes into the heart, the heart is excited and acts ; when it has expelled that blood, it lies quiescent for a time ; when blood rushes in anew, it is roused again : so natural is both the incessant action and regular alter- nation of contraction and relaxation in the heart. It is when we are so cruel as to open a living creature that. we see best both the operation of the blood as a stimulus, and 28 OF THE ACTION the manner in which the heart re-acts upon it. When we tie the iwo vena cavas so as to prevent the blood from arriving at the heart, the heart stops ; when we slacken our ligatures and let in the blood, it moves again ; when we tie the aorta, the left ventricle being full of blood will continue struggling, hending, turning up its apex, and contracting incessantly and strongly ^ and will continue this struggle long after the other parts have lost their powers. One author, whether from his awkward- ness or the delicacy ofthe subject, or really from the strength of the ventricle, assures us, that often while he has held the aorta of a Frog close with pincers, it has burst by the mere force of the heart. If, after violent struggles of this kind, you cut the aorta, even of so small a creature as an Eel, it will throw its blood to the distance of three or four inches. Thus we not only know that we can excite the heart by ac- cumulating blood in it, but that by confining the blood in it we can carry that excitement to a very high degree ; and in short, by keeping the one or the other ventricle incessantly full of blood, we can make the one heart work continually, while the other lies quiet, or is only slightly drawn by the other's motion, showing the true distinction betwixt the heart of the body and the heart of the lungs. And this is a memorable fact, that it is not merely the stimulus of the blood, but the sense of fulness that makes the heart contract; for the auricle often beats twice or thrice, sometimes it makes its push four or five times, be- fore it can force the ventricle to contract. When we empty the heart, and tie all its veins, all its parts cease to act; stimuli applied outwardly make it contract par- tially ; it trembles in particular fibres : but it is only letting in the blood, or blowing it up with air, that can bring it into full action again. When we look with cruel deliberation upon the strokes of the heart in any living creature, we observe that at first, during the full and rapid action ofthe heart, there is hard- ly any perceptible interval among the several parts ; but to- wards the end of each experiment, when the pulse flags, and the creature falls low, the swelling of the great veins, and the successive strokes of auricle and ventricle, are distinctly told. The dilatation and contraction of each part is what we cannot observe, they are so quick ; but these things we distinctly ob- serve : the auricle contracts and dilates the ventricle; the ventricle contracts, subsides, and fills the aorta ; the aorta turns and twists with the force of the blood driven into it, and by its own re-action, and the ventricle, every time that it contracts, assumes a form slightly curved, the point turning up like a tongue towards the basis, and the basis in some degree bending towards the point. The basis, indeed, is in some degree fixed Vol. II dcnio7tstreiti7i(/ the Intf/wsition cft7ic/£t'(trt. J.£W -> .» Vm-M i OF THE HEART. 29 to the diaphragm and spine, but the heart in its contraction al- ways moves upon its basis as upon a centre ; its ventricles, and especially its apex, are free ; the point rises and curves so as to strike against the ribs ; and the dilatation of the heart is such (together with the posture and relation of its several parts,) that during the dilatation the heart turns upon its axis oneway; the contraction ofthe heart reverses this, and makes it turn the other way, so that it seems to work perpetually with the turning motions of a screw. All this is most striking, while we are looking upon the motion of the heart in a living creature. The posture of the human heart is very singular, and will illustrate this turning motion extremely well; for in the human heart the posture is so distorted, that no one part has that rela- tion to another which we should beforehand expect. In the general system, the human heart is placed nearly in the centre, but not for those reasons which Dionis has assigned ; it is not in order that by being in the centre it may feel less the difficulty of driving the blood to any particular limb or part of the body ; it is the place of the lungs that regulates the posture of the heart; and wherever they are, it is. Except the Oyster, I hardly know of any creature in which the heart lies expressly in the centre ofthe body. In Frogs, Toads, Newts, and Snakes, the lungs are not moved by any diaphragm ; they are filled only by the working of the jaws, the lungs then begin under the jaws, and the heart is lodged at the root of the jaws, leaving, as in a Newt or Cameleon, Crocodile, Adder, Serpent, &c. the whole length of their trailing body behind. In a fish, the gills serve the creature for lungs ; the gills are lodged under the jaws, and the heart is placed betwixt them. In insects, as in the common Caterpillar (the aurelia of our common Butterfly,) the air enters by many pores on its sides ; and accordingly its heart is not a small round bag, but may be easily seen running all down its back, working like a long aorta, but having regular pulsations, denoting it to be the heart; and this you easily see through the insect's skin, for it is more transparent along the back where the heart is. The breast in man is divided into two cavities by a mem- brane named the mediastinum. This membrane passes di- recdy across the breast from the sternum before, till it fixes it- self into the spine behind. It is on the left side of this mem- brane, in the left cavity of the breast, that the heart is placed, lying out flat upon the diaphragm as upon a floor, by which it is supported ;* and that surface (a)—which lies thus upon the * The true position of the heart is what is represented in No. 16, and 17; where No. 16, shows the heart set upright, as I have hitherto represented it in aB 30 OF THE PERICARDIUM. diaphragm, is perfectly flat, while the upper surface (b)—or what we usually call the fore-part ofthe heart, is remarkably round. The whole heart lies out flat upon the diaphragm ; its basis (c)—where the auricles are, is turned towards the spine and towards the right side ; the apex (cQ—or acute point, is turned forwards, and a little obliquely towards the left side, where it strikes the ribs ; the vena cava (e)—enters in such a manner through a tendinous ring ofthe diaphragm,* that it ties down the right auricle to that floor (as I may term it) of the thorax; the aorta (/") does not rise in that towering fashion in which it is seen when we take a dried-up heart, which naturally we hold by its apex, instead of laying it out flat upon the palm of our hand; nor in that perpendicular direction in which hith- erto, for the sake of distinctness, I have represented it in these plans; but the aorta goes out from its ventricle towards the right side of the thorax; it then turns in form of an arch, not directly upwards, but rather backwards towards the spine; then it makes a third twist to turn downwards; where it turns downwards it hooks round the pulmonic artery (,§*),—just as we hook the fore-fingers of our two hands within one another. The right heart (hli)—stands so before the other, that we see chiefly the right auricle and ventricle before, so that it might be named the anterior heart; the pulmonic artery (g)—covers the root of the aorta; the left ventricle (i),—from which the aorta rises, shows little more than its point at the apex of the heart; the left auricle (k)—is seen only in its very tip or extremity, r where it lies just behind the pulmonic artery; and the aorta (f)—arises from the very centre of the heart. From this view any man may understand these vessels by other marks than the mere colours of an injection ; and he will also easily under- stand why the heart twists so in its actions, and how it comes to pass that its posture is difficult for us to conceive, no one part having that relation to any other part which we should be- forehand suppose. Of the Pericardium. But the pericardium, purse, or capsule, in which the heart is contained, affects and regulates its posture, and makes the my plans, while No. 17, represents its inclined position lying almost horizontally upon the floor of the diaphragm. * Let it be observed, that (?) in this drawing marks the point where the lower cava was tied close upon the diaphragm, to prevent the injection going down intp the liver. Vol.11 )///f/f//f.) oft/tePcrimrJue.ra. 'ofwhidtX"LHi*« true drawing A"/'*> a,Plan sluwifuf ds inflexion over tits, Heart / 'Ji Port of theLuTuji NT 18 • N°19 Part of die Lungs OF THE PERICARDIUM. 31 last important point concerning the anatomy of the heart. It , is a bag of considerable size and great strength, which seems to us to go very loosely round the heart, because when we open the pericardium the heart is quite empty and relaxed ; but I believe it to surround the heart so closely as to support it in its palpitations, and more violent and irregular actions ; for when we inject the heart, its pericardium remaining entire, that bag ' is filled so full that we can hardly lay it open with a probe and lancet without wounding the heart; and still further, when we open the pericardium before we inject the heart, the heart re- ceives much more injection, swells to an unnatural bulk for the thorax that it is contained in, and loses its right shape. The pericardium is formed like the pleura and mediastinum, of the cellular substance ; it is rough and irregular without, and fleecy with the threads of cellular substance, by which it is connected with all the surrounding parts ; within it is smooth, white, ten- dinous, and glistening, and exceedingly strong. As the heart lies upon the floor of the diaphragm, the pericardium, which lies under the heart, is connected with the diaphragm a little to the left of its tendinous centre, and so very strongly that they are absolutely inseparable. The pericardium surrounds the' whole heart, but it is loose every where except at the root of the heart, where it is connected with the great vessels: for the pe- ricardium is not fixed into the heart itself, but rises a conside- rable way upon the great vessels, gives them an outwTard coat, and surrounds each vessel with a sort of ring, as may be seen in the plan.* For, 1st, It surrounds the pulmonic veins where they are entering the heart; there the pericardium is short: 2ndly, It mounts higher upon the vena cava than upon any other vessel ; the cava of course is longer within the pericardi- um, and it also is surrounded with a sort of ring: 3dly, It then passes round the aorta and pulmonic artery, surrounding these m one greater loop : 4thly, The cava inferior is the vessel which is the shortest within the pericardium : for the heart in- clines towards the horizontal direction : it lies in a manner flat upon the upper surface of the diaphragm, while the lower sur- face ofthe diaphragm adheres to the upper surface ofthe liver. Thus it happens that the liver and the right auricle of the heart are almost in contact, the diaphragm only intervening ; thence the lower cava which passes from the liver into the right auri- cle of the heart cannot have any length. While the pericardi- um thus passes round the great vessels, it must leave tucks and * Vide Plan, No. iS. % 32 OF THE PERICARDIUM. corners ; and these have been named the cornua or horns of the pericardium. But there is another peculiarity in the form of the pericardi- um, which I have explained in this second plan ;* viz. that the pericardium constitutes also the immediate coat of the heart; for the pericardium having gone up beyond the basis of the heart so as to surround the great vessels, it descends again along the same vessels, and from the vessel goes over the heart itself. I have marked the manner of this more delicate inflec- tion of the pericardium at (ad)—where the pericardium is loose ; at (£&,)—the angle where it is reflected ; and at (cc,)— where it forms the outer coat of the heart. The pericardium where it forms this outer coat becomes extremely thin and deli- cate, almost cuticular, but strong : under this coat there is much cellular substance ; the coronary arteries pass along in this cel- lular substance, the muscular fibres are bound together by it, and under it the fat is gathered sometimes in a wonderful de- gree, so as to leave very little to be seen of the dark or muscu- lar colour of the heart. The pericardium then is a dense and veiy strong membrane, which I would compare with the capsule of any great joint, both in office and in form : for it is rough and cellular without, shining and tendinous within; bedewed with a sort of halitus like the great joints, delicate and almost a cobweb-like mem- brane in the child, but increasing in thickness by the continual frictions of the heart, just as a capsular ligament does by the working of its joint; and its uses are to keep the heart easy and lubricated by that exhalation which proceeds from its exha- lent arteries (and not from any glands,) and which can be imi- tated so easily by injecting tepid water into its arteries, to sus- pend the heart in some degree by its connections with other parts, especially by its connections with the mediastinum and diaphragm ; and to limit the distentions ofthe heart, and check its too violent actions, just as we see it prevent too much of our injections from entering the heart. How strong the pericardi- um is, and how capable of supporting the action of the heart, even after the most terrible accidents, we know from this; that the heart or coronary arteries have actually burst, but with a hole so small as not to occasion immediate loss of life ; then the pericardium receiving the blood which came from the rup- ture, has dilated in such a manner as to receive nine or ten pounds of blood, but has yielded so slowly as to support the No. 19. OF THE PERICARDIUM. 33 "heart in some kind of action, and so preserved life for two or three days. If I have not mentioned any fluid under the direct name of AOjja pericardii, or the water of the pericardium, it is be- cause I consider the accident of water being found as belong- ing not to the healthy structure but to disease. Yet this same water occupied the attention of the older authors in a most lu- dicrous degree. Hippocrates believed that this water of the pericardium came chiefly from the drink we swallow, which found some way or other (as it passed by the pericardium) to insinuate itself into this bag: some after him said, it was the fat of the heart melted down by incessant motion and the heat of the heart ; some said it was from humours exuding through the heart itself, and retained by the density of the pericardium that this water came ; and it is but a few years since this clear and distinct account of it was given, viz. " that it proceeds from the aqueous excrementitious humour of the third con- coction." The same " sad and learned men,* viri graves et docti," declare to us, that the uses of the aqua pericardii are to cool the heart, for it is the very hottest thing in the body ; or by its acrimony to irritate the heart, and support its motions ; or to make the heart by swimming in it seem lighter. By this it is pretty obvious what absurd notions they had ofthe quanti- ty of water that may be found in the heart. But of all the outrages against common sense and common decorum, the most singular was the dispute maintained among them, whe- ther it was or was not the water of the pericardium which rush- ed out when our Saviour's side was pierced with the spear ? The celebrated Bardius, in a learned letter to Bartholine, shows how it was the water of the pericardium that flowed out; but Bartholine, in his replication thereunto, demonstrates, that it must have been the water of the pleura alone. This abominable and ludicrous question, I say, they bandied about like boys rather than men: Bartholinus, Arius Montanus, Bertinus Nicelius, Fardovius, Laurenbergius, Chiprianus, with numberless other Doctors and Saints, were all busy in the dis- pute ; for which they must have been burnt, every soul of them, at the stake, had they done this in ridicule ; but they proceed- ed in this matter with the most serious intentions in the world, and with the utmost gravity, f The whole truth concerning * They are thus denominated in all the charters of the College of Physicians from the time of Henry VIII downwards. t The shocking indecencies of their reasonings on this subject I will not conde- scend to draw out from the obscurity of that barbarous idiom in which was deliver- ed : '«Scd non cogar hue me conferre. Fateor enim nativaui Chnsti temper uRi Vol. II. E 34 OF THE PERICARDIUM. water in the pericardium is, that you find water there whenevei at any time you find it in any of the other cavities of the body. If a person have laboured under a continued weakness, or have been long diseased, if a person have lain long on his death-bed, if the body have been long kept after death, there is both a con- densation of the natural halitus in all the parts of the body, and an exudation of thin lymph from every vessel; there is water found in every cavity, from the ventricles of the brain to the cavity of the ankle joint, and so in the pericardium among the rest. But if you open any living animal as a Dog, or if you open suddenly the body of a suicide, or a criminal who has been just hanged, not a drop of water will be found in the peri- cardium. When such fluid is to be found, it is ofthe same na- ture with the dropsical fluids of other cavities: in the child, and in young people, it is reddish, especially if the pericardium be inflamed ; in older people it is pellucid, or of a light straw colour ; in old age and in the larger animals it is thicker, and more directly resembles the liquor of a joint. Thus does the pericardium contribute in some degree to set- tle the posture of the hearty but still the heart is almost entire- ly loose and free. It is fixed by nothing but its great vessels as they run up towards the neck, or are connected with the spine ; but how slight this hold is, how much the heart must be moved and these vessels endangered, by shocks and falls, it is awful to think. The pericardium is no doubt some restraint: its connections with the diaphragm and with the mediastinum make it a provision, in some degree, against any violent shock; its internal lubricity is, at the same time, a means of making the heart's motions more free : yet the heart rolls about in the thorax, we turn to our left side in bed, and it beats there ; we turn over to our right side, and the heart falls back into the chest, so that its pulse is no where to be perceived: we incline to our left side again, and it beats quick and strong. The heart is raised by a full stomach, and is pushed upwards in dropsy : and during pregnancy its posture is remarkably changed; it is suddenly depressed again when the child is delivered, or the waters of a dropsy drawn off. It is shaken by coughing, nihil pravorum humorum produxisse, quia perfectissima; at a causis extemis, vigiliis, cruciatibus, itineribus, vulneribus et mille tormentis quid non praeter consuetam naturae divinaz perfectionem productum credimus ? Ad hsec sano sensu id accipicn- dum, nihil pravorum humorum in corpore Christi generatum.'' Bartholin* Epistola% p. 199.—" Idque de Salvatore innoxie dixeris, quern scimus manducasse, bibisse, dormivisse, ambulasse et quid non egisse, ut se hominum cunctis actionibus, quae secundum naturam sunt, submitteret: sputum emisit, quum luto misceret ad curan- dum coecum, et sudavit ingruente martyrio, et sine dubio non parum seri in thorace collegit, quod, aperto post mortem latere, emanavit." Bartholin': Ep'utola,p. 300. OF THE HEART. 35 laughing, sneezing, and every violent effort of the thorax.__ By matter collected within the thorax it may be displaced to any degree. Dr. Farquharson cured a fine boy, about eight years old, of a great collection of matter in the chest, whose heart was so displaced by a vast quantity (no less than four pounds) of pus, that it beat strongly on the right side of the breast while his disease continued, and as soon as the pus was evacuated, the beating of the heart returned naturally to the left side. Who could have believed that, without material in- jury, the heart could be so long and so violently displaced ? Felix Platerus tells us a thing not so easily believed, that a young boy, the son of a printer, having practised too much that trick which boys have of going upon their hands with their head to the ground, began to feel terrible palpitations in the left breast; these gradually increased till he fell into a dropsy from weakness, and died ; and upon dissecting his body, the situation of his heart was found to have been remarkably chang- ed by this irregular posture. Now we are not to argue that such change of posture of the heart could not happen merely from this cause, because professed tumblers have not these dis- eases of the heart; it were as silly to argue thus against the au- thority of Platerus, as to say that every post-boy has not aneu- risms ofthe ham, or that every chimney-sweep has not a cancer of the scrotum. We may now close this chapter on the mechanism of the heart, in which all the parts have been successively explained. We know how the heart is suspended by the mediastinum and by its great vessels ; how it is lubricated, supported and regu- lated in its motions, by the pericardium ; its nerves, which re- main to be explained at a fitter time, are extremely small, while its vis insita, or irritability, is great beyond that of all the other parts. We can easily follow the circle of the blood, which, as it arrives from all the extremities, irritates the auricle, is driven down into the ventricle, is forced thence into the pulmonic artery, pervades the lungs, and then comes round to the left side of the heart, or to that heart which supplies the body; and there be- gins a new circulation, called the greater circulation, viz. of the body, as the other is. called the lesser circulation of the lungs. Thus we recognise distinctly the functions of the dou- ble heart, with all its mechanism; the stronger heart to serve the body, the weaker heart to serve the lungs ; and we see in the plainest manner two distinct functions performed by one compound heart: thc right heart circulates the blood in the lungs, where it is purified and renewed ; the left delivers out a quantity of blood, not such as to fill all the vessels, nor such as to move onwards by this single stroke of the heart to the 36 OF THE HEART. very extremities of the body, but such merely as to give a sense of fulness and tension to the vessels : the force is merely such as to excite and support that action which the arteries every where perform in the various organs of the body, each artery for its appropriated purposes, and each in its peculiar degree. By understanding thus the true mechanism and uses of the heart, we can conceive how the ancients were led into strange mistakes, by very simple and natural appearances. We un- derstand why Galen called the right auricle the " ultimum mo- riens," or the part which died last; for, upon opening the bo- dy soon after death, he found the right auricle filled with blood, and still palpitating with the remains of life, when all the other parts seemed absolutely dead ; and if the blood always accu- mulates in the right side of the heart before death, it is plain that the stimulus of that blood will preserve the remains of life in the right side, after all appearance of life on the left side is gone. But the cause of this accumulation of blood in the right side is very ill explained by Haller, though it seems to have employed his thoughts during half his life. He says that in our last moments we breathe with difficulty ; the lungs at last collapse, and cease to act; and when they are collapsed, no blood can pass through them, but must accumulate in the right side of the heart. That there is really no such collapse of the lungs, I propose hereafter to show ; but, in the meanwhile, this is the true reason, viz. that when the ventricles of the heart cease to act, and the beating of the heart subsides, the two au- ricles lie equally quiet, but in very different conditions : the right auricle has behind it all the blood of the body pouring in from all parts during the last struggles ; but the left auricle has behind it nothing but the empty veins of the lungs ; nothing can fill it but what fills the vessels of the lungs ; or, in other terms, nothing can fill the left auricle but the stroke of the heart itself; but instead of acting, the heart falls into a quiescent state, the left auricle remains empty, while the blood oozes into the right auricle from all the extremities of the body till it fills it up. Nothing is more agreeable than to find such phenomena described faithfully long before the reason of diem is under- stood. In the Parisian dissections I find the following des- cription : " When the breast of a living Dog is opened by taking away the sternum, with the cartilaginous appendices of the ribs, the lungs are observed suddenly to sink, and afterwards the circulation of the blood and the motion of the heart to cease. In a little time after that the right ventricle of the heart and the OF THE HEART. 37 vena cava are swelled, as if they were ready to burst."* This was what deceived the ancients, and was the cause of all their mistakes. When they found the right ventricle thus full of bloocL, they conceived that it alone conveyed the blood ; they found the left ventricle empty, and believed that it contained nothing but vital spirits and air : and so far were they from having any notions of a circulation, that they thought the air and vital spirits went continually forwards in the arteries ; that the gross blood which was prepared in the liver came up to the heart to be perfected, and went continually forwards in the veins, or, if they provided any way of return for these two fluids, it was by supposing that the blood and spirits moved forwards during the day time, and backwards in the same ves- sels during the night. These things next explain to us why they called the right ventricle ventriculus sanguineus : they found it full of blood, and thought its walls were thinner, because it had only to contain the very grossest parts of the blood ; and why they called the left ventricle ventriculus spirituosus and nobi- lis, because they saw it empty, and concluded that it contain- ed the animal spirits and aerial parts of the blood, and its walls were thicker, they said, to contain these subtile spirits. They explain to us their names of arteria venos a and vena arte- Riosa ; for they would have veins only on the right side ofthe heart, and arteries only on the left; and although they saw plainly that the pulmonic artery was an artery, they called it Arteria Venosa ; and although, on the left side again, they saw plainly that the pulmonic vein was merely a vein, they would still cheat themselves with a name, and call it Vena Arteriosa : the veins they said, were quiet, because they contained nothing but mere blood ; the arteries leaped, they said, because they were full of the animal spirits and vital air. The very name and distinction of arteries which we now use, arise from this foolish doctrine about air and animal spirits.— To the oldest physicians there was no vessel known by the name of artery, except the aspera arteria ; and it was nam- ed Artery because it contained air ; so that Hippocrates, when he speaks of the carotids, never names them arteries, but calls them the Leaping Veins of the neck. But when Eristratus had established his doctrine about the vessels which go out from the heart, carrying vital spirits and air, the name of arte- ry was transferred to them : and then it was that the ancients began to call the vessels going out from the left side ofthe heart * Page 261*. 38 OF THE HEART. arteries, naming the aorta the arteria magna and the pul- monic vein the arteria venosa. When a vein was cut, they saw nothing but gross blood, and of a darker colour ; but when an artery was cut, they observed that the blood was red ; that it was full of air bubbles ; that it spurted out, and was full of animal spirits ; and thus it became easy for them to show how safe it was to open a vein where no- thing was lost but gross blood, how terribly dangerous it was to open an artery which was beating with the spirit of life j and this they considered as such an awful difference, that when arteriotomy in the temple was first proposed, they pronounced it murderous, and on this reasoning it was absolutely forsaken for many ages. But the oldest of our modern physicians soon found a neces- sity of mixing this blood and animal spirits together, and for a long while could hit on no convenient way by which this mix- ture might be effected : as a last shift, they made the blood ex- ude through the septum of the heart; and then the current doc- trine was, that of the blood which came from the liver, one half went into the pulmonic artery to nourish the lungs ; the other half exuded through the septum of the heart to mix with the animal spirits. Riolanus was the bitter enemy of Harvey and of his noble doctrine; and this is the miserable and confused notion, not to call it a doctrine, which he trumpeted through Europe in letters and pamphlets. To make good this misera- ble hypothesis, Riolanus, Gassendus, and many others, saw the necessity of having side passages through the septum of the heart. I really believe from their mean equivocating manner of talking about these passages, that they had never believed them themselves.* " The chyle," says Bartholine, " and the thinner blood, passes through the septum of the heart, when the heart is in systole and the pores and passages are enlarged."— Thus did the celebrated Bartholine believe the septum perfo- rated. Wallseus, and Marchetti, and Mollinettus, and Moni- chen, believed it, and Mr. Broadbecquius of Tubingen prov- ed it.f But I believe most potently with Haller, that whenever they wanted to show those perforations, they managed their probes so as to make passages as wide and as frequent as the occasion required : " Solebant foramina parare adigendo sty- los argenteos in resistens septum," says Haller; and this is a full and true account of all the authors who have described * That I may not seem to speak too harshly of this knot of conspirators against Harvey, I will quote what Boerhaave says of Riolanus, who was at the head of them : " Non ipse callidus cavillationum artifex Riolanus,'' &c. f Experimento perf< ratum ostendit Broadbecquius Tubingas. OP THE HEART. 39 side passages through the septum of the heart: they needed them, and they made them. Amidst all this ignorance, we cannot wonder that a thousand childish imaginations prevailed, nor that the qualities of the mind were deduced from the physical properties of the heart. We have heard the vulgar, for example, speak of the bone of the heart. And from whom did this arise ? From Aristotle ! who explains to us, that there is at the root of the heart a bone which serves for its basis ; and not a physician has written up- on the heart since his time, who has not spoken more or less mysteriously about this bone : while in truth the whole story means nothing more than this, that where the basis of the arte- ries are fixed into the hard ring or basis of the heart, the place is extremely firm, almost cartilaginous, especially in old age, when often the roots of the arteries are ossified, or converted into what anatomists have chosen to call bone. Often also we have heard the vulgar talk, not figuratively, but in the plain sense of the words, of a little or big heart, as synonymous with a timorous or courageous heart. But when- ever we hear mistakes of this kind among the vulgar, we may be assured they have some time or other come from high au- thority. Bartholine was so much convinced that a small heart begot courage, and a great one irresolution and fear, that he is thoroughly surprised when he finds the contrary ; " Cor vastus fuit homo, tamen audax fuerat, ut cicatrices in capite frequentes et rimae in cranio testabantur." But if Bartholine be right, Kirkringius is quite wrong, and has mistaken the doctrine ; for he says, " An magnanima fuerit hsec magni cordis fcemina, nescio," &c. " I do not know whether this woman's courage was as big as her heart; but this I do know, that she was a fa- mous toper. Whether this drinking dilates the heart, and makes your staunch drinkers such famous fighters, I cannot pretend to decide." We have heard the vulgar talk also of a hair}- heart, as familiarly as of a hairy man, being the mark of high courage and strength ; but what shall we think of it, when we find that this report is to be deduced fairly from Pliny, through the most celebrated names among our old physicians ? He it was who began with telling how the Messenians, that unhappy people who lived for so many ages the slaves or helots of Greece, lost their great general Aristomenes. But how great he was, never, according to Pliny, came to be known till ;ifrcr his death ; for the Lacedemonians having catched him three times, resolved at last to open his breast; and there, as a proof of his most invincible courage and daring, they found his heart filled widi hair. This from Pliny were nothing, if such 40 OF THE HEART. dissections had not been made since then a hundred times.— " There was a robber (says Benivinius,) one Jacobus, who having been taken down from the gibbet apparently dead, but really having in him the remains of life, was laid carefully, re- covered, was perfectly restored, betook himself to his old ways again ; and so in the natural course of things came round to his old mark the gallows, and was this time very thoroughly hang- ed. Wondering (says Benivinius) at the perfect wickedness of this man, I longed very anxiously to dissect the body, and I actually found the heart, not covered, but (refertum pilis) crammed with hair." But there is, in fact, no end of wonders and wonderful dis- sections among these robbers of his. His next subject was not a bold robber, but a poor sneaking thief (de corde furis cujus- dam ;) there was no hair to be expected in his heart; but as he was a thief only, it was consistent with this doctrine that he should be first very heartless ; secondly, have very little brain; thirdly, that he should have very inordinate appetites and de- sires. Now there was first a great two-legged vein carrying the atrabilis, the source, no doubt, of all his inordinate cra- vings, directly into the stomach. Secondly, there was a great abscess full of pus wasting the left side of his heart; and, third- ly and lastly, the back part of the head, (which all the anato- mists of that time knew very well was the seat of memory) was in him so small that it could hardly contain a spoonful of that kind of brain ; and this want was the reason (having so little memoiy) that he was so persevering a thief ; for let you whip him, banish him, clap him in the stocks, he forgot it straight- way, and was back at his old tricks again, like a dog to his vomit."* But these are now almost forgotten, though perhaps the his- tory ofthe absurdities ofthe human genius should no more be neglected than of its beauties. Is it not delightful to feel, that after floating in this ocean of conjecture, after all these disor- derly and wild dreams, we are come to have an idea of the heart, simple and beautiful; of a heart containing within it- * " Non videntur silentio esse praetereunda, qu«e nuper in inciso Jacobi cujusdam furis insignis cadavere annotavlmus: bifurcatam scilicet venam quse a liene ad ven- triculum atram defert bilem, turn et abscessum in sinistro cordis ventre pituita redun- dantem: postremo et posteriorem ejus capitis partem, ubi memorise sedes est, adeo brevem, at tantillam cerebri portiunculam contineret. Quam ob causam, cum pri- orum scelerum et eorum quae pro his saepe passus fuerat, tormenta scilicet, exilia et carceres minime recordaretur, toties ad vomit urn tanquam canis impudens reversus est, ut in laqueum tandem incident, vitseque bq furti finem fecerit."— Vid. Benefiniur. OF THE BLOOD. 41 self two functions ; first, the office of renewing the blood j secondly, the office of animating the arteries, and by them pre- serving in life and action the whole system ofthe body ? These are the two offices which I shall now proceed to explain. CHAP. II. ON THE APPEARANCE AND PROPERTIES OF THE BLOOD, ON THE CHEMISTRY OF OUR FLUIDS, AND ON THE INFLUENCE WHICH AIR HAS UPON THEM. JjY the simplest methods the blood can be resolved into vari- ous parts, but chiefly into these three ; the red globules, which give colour to the blood ; the gluten, which gives consistency and nutritious qualities to the blood ; and the serum, which dilutes, mixes, and suspends the whole. Though the serum and gluten did not pass entirely unnotic- ed, the red globules were the part of the blood which first ex- cited the attention of physicians, and seemed to promise a rich harvest of discoveries ; a promise which too surely never was fulfilled. The red particles have always appeared important, be- cause they seem to give the colour, the useful qualities, and the whole character to the blood. It is by the rolling of the red particles only that we see the circulation in the microscope ; it is red blood only that we ever name as blood ; and the colour of the red blood changes in health and disease. But when physicians studied this part alone, when they gave it the mark of chief importance, annexed to it alone the name of blood, they little thought how far they over-rated its importance, how far the red particles are from nourishing the system, from be- ing essential to the blood, from being universal in all creatures. They had not considered what myriads of animals, great as well as small, want the red particles, and (if these red parti- cles are to be the characteristic) want blood ; while philoso- phers of less contracted notions have continued to call that flu- id, blood, which fills the vessels of plants. The Harvcian doctrine had no sooner produced a revolution Vol. II. F J.0 OF THE BLOOD. in the general doctrines of physiology, or physicians begun to think of the heart and its circulation, of the great arteries, and extreme vessels, of the difference betwixt arteries and veins, and of the ways in which the fluids move through the smaller tubes, (for the) saw them moving by their microscopes) no sooner did all these phenomena and new wonders present them- selves to their imaginations, than they thought also of curious ways by which these motions and secretions might be explain- ed. They then began to estimate the calibres ofthe arteries, to calculate with great affectation of care the shape, the size, the composition, as they chose to call it, of the particles of the blood ; chimeras and fancies sprung up innumerable ; and it happened unfortunately that for a long while physicians studi- ed nothing but angles, and logarithms, and algebraical equa- tions ; they reasoned according to those sciences only which have no connection with the physiology of the animal body ; they calculated the force, the thickness, the dimensions of die heart ; the diameter, and the strength of walls, and the direc- tion of the aorta ; their experiments consisted in fixing clumsy tubes into the arteries, or in calculating the whole quantity of blood by bleeding an animal to death ; they applied nothing but the laws of hydraulics, i. e. of fluids rising and falling in ri- gid tubes, to explain the active arteries of a living body: in short, in explaining the living body they forgot that it was alive. But now the age of infallible proofs and demonstrations has passed over, and the works of Keill, Pitcairn, Borelli, are quite neglected. This disordered and miserable state of science, which con- tinued for a century nearly, arose from those red particles of the blood engrossing too much attention, and from their being allowed an importance which does not belong to them; although one must still acknowledge that they are very surprising, be- cause they are very unaccountable, at least I do not know that any natural or likely use for them has been yet assigned. Leeuwenhoek, looking through his glasses, saw that this which gave the red colour was the most permanent character- istic part ofthe blood : he saw that this part consisted of red particles floating in the serum ; he found, or pretended to find, that they were of the same size in a Man as in a foetus ; in a Chick as in a Hen ; in a Whale or Elephant, he found them the same as in a Mouse or Minnow ; merely because it was con- venient for him to find it so. But poring still longer over these particles, he perceived that the great globules were so far imperfect as often to break in pieces, and roll about in the serum in separate parts ; and he niwnvs found that there were six less parts composing the OF THE BLOOD. 4J greater globule of the blood. By looking more and more, he pretended to observe, that these smaller parts into which the red globules broke down still preserved their form ; that these were the particles ofthe serous part ofthe blood ; and that the great or red particles frequently broke down into serous parti- cles, and these again as frequently united and composed afresh a red globule. He pretended to find, that exactly six smaller globules went to make up one great one ; and he called the red and serous globules the globules of the first and second order. By this notion of orders it was plain that he intended to plunge deeper into this hypothesis, and to have at least a third and fourth order ; besides, these orders and particles were at his call, he might do as he pleased ; and he was almost the on- ly person possessed of glasses which could enable the physiolo- gist to see and tell about them. He pored till he believed, or at least made others believe, that he saw globules of a third or- der, six times smaller than the serous globules, and. of course thirty-six times smaller than the red globules. And thus he had lymphatic particles, six of which made up one serous par- ticle ; and serous particles, six of which made one red glo- bule. To the geometrical physiologists of that day all this instruc- tion concerning the structure of the blood was most delightful ; it corresponded very notably with their calculations about regu- larly descending series of vessels ; and a most curious method did they find out for settiing this law of the branching of arte- ries. They took the plates of Eustachius, measured with com- passes the arteries and veins, estimated the angles at which each branch goes off, compared the several branches with the parent trunk ; and from such calculations they settled the gen- eral law as heartily and freely, as if, instead ofthe most extra- vagant plates in all anatomy, they had been measuring actually the human body itself. Thus they had set up their doctrine of angles, branches, anastomoses, trunks, and extreme vessels : they had found that there was a regular series of descending arteries ; they had a tube now suited to every descending parti- cle that Leeuwenhoek could invent; and when a particle had got into a wrong vessel, ic could go back till it found a tube that suited it: or if driven into a wrong bore, it could break itself down into serous or lymphatic particles. But when many par- ticles did stick hard in the strait places, then there was an error loci; then the big particles were out of their peculiar vessels, and then the part began to be red : thence came inflammations, fevers, deeper obstructions ; and from such causes, or from the breaking clown of the blood and humours, came every disease hat could be n amed. 44. OF THE BLOOD. So very greatly were they delighted with the discovery, that Dr. Martin, who had measured the vessels, as I have just told, and had dreamt over this the longest and soundest of them all, speaks of it in these rapturous terms. " But we are moreover certain from the observations of that most accurate and curious observer of the minima naturae, that there are innumerable ves- sels of such asmallness that none of these globules could pass ; so that it is necessary to suppose inferior classes of globules of the fourth, fifth, sixth, and other orders.—Whence by analo- gy we are to conceive globules of the third order made up of six globules ofthe fourth order, and these of six ofthe fifth or- der, and so on ad infinitum through various degrees, the num- ber of which we are not to take upon us to determine." This is a pleasant addition of Dr. Martin's ; and makes it a most manageable system of most dilatable materials, stretching so as to suit all occasions. This rider or codicil to the doctrine made it easy for every particle to pass every vessel; but, alas ! it leaves no room for that old catchword of the system, the er- ror loci, nor any provision for making diseases. How all the physicians in Europe could digest this absurdi- ty, of yellow particles, by aggregation and arrangements in sixes and sixes, becoming red, it is not easy to conceive ; nor is it easy to conceive how men, whose education in mathema- tics and algebra should have taught them to think accurately and reason closely, could believe that globules should break down into six particles each, and that these particles, being themselves particles of serum, should yet be distinctly seen floating in the serum. How could these geometrical physi- cians possibly believe, that these particles, from large to small, should descend, not gradually and imperceptibly, but by sixes and sixes, one after another like steps of stairs ? In all his ma- thematics, I do not believe that Martin could find any contri- vance fit to help him out of these difficulties. Martin observes, in his own way of geometry, and proceeds to prove it by most laborious schemes, u that just six small sphericles should go to make up one larger globule, if you were to choose the most convenient and firmest way of constructing it;" and then he wonders at Leeuwenhoek finding it exacdy so. But if Leeu- wenhoek knew this as well as Dr. Martin, I cannot for my heart think it any wonder that Leeuwenhoek chose " the most convenient and firmest way of constructing a red globule, viz. out of six smaller ones." Seeing that he had the affair entirely in his own hands, " what a beautiful harmony and regular- ity do we perceive, says Martin, in the mass of blood ? Mag- num certe opus oculis video." In plain truth, they desired but OF THE BLOOD. *S a little of this harmony, a little consistency in their doctrine and all was well. But the mistakes concerning the formation or organizing of this blood are worse than these ; for they came from men truly learned, and diligent in anatomy, led on by too strong a desire of finding out the uses of several parts of the human body, as of the Spleen and Thymus, parts hitherto unexplained. Mr. Hewson supposed that the lymphatic glands, which seem at first to be mere convoluted vessels, but which microscopes shew as consisting of numerous cells, form in these cells the primordia of the red blood ; for each red particle he supposes to consist of a central particle, which is solid and dark-co- loured, surrounded by a vesicle which is transparent or white ; and this dark or central part he supposes is formed in the lymphatic cells ; for he finds a sort of round particles in the lymph, and often he finds the lymphatics full of red blood. Next, he has supposed that in die child there is required a much greater supply of blood; for this purpose is the thy- mus appointed; viz. to assist the lymphatic glands in organiz- ing blood. This gland lies in the upper part of the chest, is great in the child, has vanished in the adult, but while it exists, he finds it full of a milky juice or whitish mucus, fit to make central particles for the blood; and the lymphatics, as he supposes, are the excretories for this gland. He next conjectures, that this work, begun thus by the lymphatic glands, and thymus; is perfected by the spleen; that the lymphatics make central particles only, while the vesicular coverings are formed in the spleen; so that there Only do the particles become perfect; and accordingly of these parts it is in the spleen alone that the red blood is found. As the central particles are formed in the cells of the lymphatic glands, the vesicular parts are formed in the cells of the spleen, and the lymphatics unload these cells of the parti- cles when completely formed: but there appears no other proof that they do this office than that there are cells in the spleen which may make vesicles; and that the lymphatics being tied, and the spleen squeezed, red globules are sometimes found in them. Long poring over a wearisome subject, and an intense de- sire to finish that account of the blood which he had so suc- cessfully begun, are strong apologies for all these mistakes. No man will venture to deny, that the glands and lymphatic vessels probably accomplish some important changes upon all fluids which pass through them; but that they alone organize the blood is not to be conceived. Their containing round white particles, argues nothing; these exist in the. chyle, and 46 OF THE BLOOD. probably in that condition pass into the blood. But if the foetus requires a great supply of blood, and the thymus assists the lymphatic glands, how comes it, when both lymphatic glands and thymus are working in concert to prepare a great quantity of blood, that the spleen, which is to finish all these particles, and to make vesicles for them, is not in a child as big as its liver is ? That red globules are found in the lymphatics, and most especially in the lymphatics of the spleen, is a most ordinary occurrence, and quite intelligible. There are not found any where, not even in the spleen, imperfect globules advancing in their organization; on the contrary, those which we do find are full formed globules which have been forced out of the common line of the circulation; they are extravasated, and taken up by the absorbents before death ; or they are squeezed into them by handling after death. If we want to have an example of the first, we have but to inflame a part and tie up its lymphatics, and then many red particles are found in them ; the second we see every time we either look for, or prepare the lymphatics of the spleen, or of any other soft viscus ; for by- handling and squeezing, the blood passes through the small breaches occasioned by this violence into the lymphatics ; if we allow the part to spoil, then air is generated, and, by handling it, air passes into the lymphatics in the same way. But the spleen is essential to finish the work ; it makes the vesicles, and has cells for the business ; and yet this part, which has the most important of all offices, viz. that of or- ganizing the general mass of blood, is every day cut out from Dogs and other animals, and they never feel the loss, nor de- cline in health. There is not the smallest doubt that the spleen has protruded at wounds, and been strangled, and so cut off. Every day we find it more or less diseased ; some- times it has swelled to thirty or forty pounds ; sometimes it has been reduced to an extremely small size ; sometimes it has been found like an empty bag. In the foetus, as in a Chick for example, red blood circulates in great profusion long before its lymphatics, spleen, or thy- mus, can be seen to exist; whereas, on the contrary, since the Chick is insulated, and has no red blood from the mother, the spleen should have been first coloured, and all the red blood of the system shoidd have emanated from the spleen. It is but a poor evasion to say, in answer to these objections, a some other part may perform this office of the spleen." What other parts will perform the office of the liver, if it be wanting ? or of the kidney, or of the testicle, or of any other gland ? or will the testicle secrete urine, or the kidney secrete OF THE BLOOD. *r bile ? What gland, then, will be able to perform so peculiar an office as this of adding vesicles or coverings to the central parts of the blood. After all this long dream about the vesicles and their central parts, the best physiologists of the present day seem to deny that they exist. But one author has finished this career of useless specula- tion, by maintaining that the life is in the blood : and thus we have seen this simple and beautiful subject of the blood tortured through all kinds of imaginations, and running its fiery ordeal, first through mathematics, then through anatomy and all its glands, then through metaphysics ; till at last we are come to talk with the most perfect ease and confidence about the most monstrous of all absurdities, the life of the blood. " For in the blood is the life thereof," might be a useful doc- trine among the Jews, if it moderated their desire for blood ; and if among physicians this were to be the tendency of such a doctrine, it were very cruel and unnatural to disturb it: but, in serious earnest, it introduces into modern physiology nothing but a jargon of words, and perverts every idea that the mind of man can form of parts which excite and parts which act. Whimsical theories creep faster into physic than useful facts ; and the business is fairly enough begun when surgeons, dissecting aneurisms of the carotid arteries, and who should be employed in recording how and from what causes they have arisen, or hoAV such diseases affect the arterial coats, choose rather to inform us " that this state of the blood, or rather of the coagulable lymph, may arise from some connection or s\ mpathy it may have with the diseased state of the artery." " By lightning (says a celebrated au- thor), death is so instantaneously produced in the muscles, that they cannot be affected by the stimulus of death." Connec- tions, and unknown sympathies, and living powers in fluids, and energies, and efforts, and intentions, and " sympathetic congelations in the blood," and " immediate sympathetic con- tiguous harmonies of cut parts," and the " diffused principle of life," and " the stimulus of death ;" are words which physio- logy would gain by losing, and are the very cant belonging to the doctrine which I propose to refute. It is not merely the doctrine of a living principle existing in the blood that is now to be spoken of, but a doctrine attributing the life of the solids to this living principle of the blood ; so that it may be intitled " the new theory concerning the blood which is itself alive, which gives life to all the other parts, and which in the beginning forms all the parts out of itself in the 48 OF THE BLOOD. mother's womb ;" so that a foetus is merely a speck of blood, and all the parts being formed from that speck of blood, the whole of physiology is abrogated henceforward, and totally annulled, except this theory itself.. It is like the staff of Moses converted into a serpent, which ate up the serpents of all the magicians who had thrown down the staff before him ; for if this theory were once established, there would remain nothing to be done in all the animal body but what was done by the blood ; nothing to wonder at, nothing to guess about, nothing to study, but this vital and plastic power of the blood. The author of this doctrine shows us two or three specks in an incubated egg; he tells us that they are dots of blood ; he tells us that this blood forms the vessels in which this blood it- self is to move ; it forms the limbs of the Chick which these vessels are to serve ; the bones, muscles, bowels, glands, the whole creature is formed out of it; and when the bird is de- livered from the egg, the living principle of the blood still continues to support it. The blood heals its flesh or bones when they are broken ; " the blood moves in the living solids, which it both forms and supports." It is not easyr to say on which of all his proofs Mr. Hunter chiefly relies for establishing a doctrine so important as this is; whether he considers it as a perfect proof of the vitality of the blood that it coagulates, or that this coagulum has more- over the power of becoming perfecdy alive, and of forming new vessels within itself; or that blood seems to assist the union of contiguous* parts ; or that by taking away its blood a creature dies ; or that a limb falls into immediate gangrene when its vessels and its supply of blood are cut off. But chiefly he seems to relyr on coagulation as a proof of the vitality of the blood ; for he considers the coagulation of the chyle as a proof that it also is alive; and he says, " contraction is the life of the solids ; and if we can find any thing like it (by which he means coagulation), we shall call it the living prin- ciple of the blood." But what harmony he can find betwixt the occasional, vo- luntary^ regulated, contractions of the living solid, and this sudden, irretrievable, inorganic, coagulation of the blood, I cannot conceive. Does not jelly coagulate ; and what is it but a part of the blood ? Does not glue congeal, dissolve, and congeal again, yet what is it but an animal jelly ? Does the blood itself ever congeal till it is out of the body, or extra- vasated in aneurismal sacs ? When it is out of the body, it coagulates ; when it coagulates, it is dead ; coagulation is so far from resembling the contractions of the living body, that it is the marked character of dead animal matter, which you OF THE BLOOD. 49 melt and coagulate again and again. Shall we then define life by saying, coagulation is the mark of the vital principle ? If so, we give the mark of its death as the proof of its living power. But in his awkward attempts to prove this point, the author has brought himself into great suspicion, and of course into great dishonour, by two experiments, in which he endeavours to show how this vital power, like the life of a perfect creature, is affected by cold first. In page 7"9, we are informed, that a fresh egg, in consequence of being alive, resists the cold, and is frozen with great difficulty ; but being once frozen and thawed again, it loses its living principle and its power of re- sisting cold at once ; it freezes now at the same temperature with other animal matter, showing no longer any power of generating heat, or resisting cold. But we are told*, that the blood having a determined period for coagulating, you may, during that time, freeze the blood, and it will thaw again, and yet congeal at its proper time; and he tells us, that he had very cleverly frozen blood in the very time of its flowing from the vein, then thawed the cake, and still in due time it congealed. Now since the egg resists cold by its living principle, why did it die or lose that living princi- ple when converted into ice ? or rather, since the blood coa- gulates through its living principle, and by a living effort, how did it preserve its living principle after being frozen ? This proves surely, either that the blood's coagulation has no rela- tion to any living principle, and therefore is not affected by the cold j or that the egg has a living principle of a very different kind, which is absolutely and totally extinguished by cold. I am sure, that had Mr. Hunter seen these two experiments brought face to face in this manner, he would have put one of them at least back quietly into the portfolio from which they^ both came. I have always observed, that your great tellers of of experiments need to have good memories ; and I am come to look on a suite of experiments as coolly as upon a set of neat plans and figures by which the author chooses to illustrate his hypothesis. That this coagulum, being once formed, has the power of becoming more perfectly alive, and forming vessels within it- self, it is not easy- to conceive. Nothing indeed is more com- mon than clots of blood, or depositions of the coagulable part, becoming highly vascular, by vessels shooting into them from surrounding parts ; but this is of no value in Mr. Hunter's • Page 87. Vol. II. G 50 OF THE BLOOD. doctrine ; this is not the fact which he means to speak of; this is much too natural and easy for him ; and that his meaning may neither be misrepresented nor mistaken, I quote his words : " When new vessels are formed, they are not always elongations from the original ones, but vessels newly formed, which afterwards open a communication with the original."— That a clot of mere blood should have in it a living principle, and should possess through that principle the power of forming within itself arteries and veins, a new and independent circula- tion ; that it should have the privilege of knowing when it should exert itself thus, is really wonderful; that it should have some kind of intelligence ; or consciousness, by which it could understand when it were within and when without the body ; and whether in certain circumstances it were fit that such ves- sels should be formed! That clots should have been busied forming vessels within them for ages, and no body ever have seen the process going on ! That Mr. Hunter, who has been looking out for vascular clots for thirty years, never should have seen this phsenomenon, is all very surprising. Mr. Hun- ter falls into a deeper blunder in this business than in the affair of the frozen egg ; he absolutely never saw a proper vascular clot. He informs us most deliberately in page 92, " that he thinks he has been able to inject what he suspected to be the beginning of a vascular formation in a coagulum, when it could not derive any vessels from the surrounding parts." From whence then did this clot derive its injection ? this is a question which detects at once what Mr. Hunter was doing, and puts this experiment pretty much upon a footing with the frozen egg- To say " that the blood, in some circumstances, unites living parts by a sort of contiguous sympathy as certainly as the yet recent branches of one tree unite it "with another," is to put forth a syllogism, in which both major and minor propositions are untrue. First, it is not true, that it is the juices of the tree which unite the graft to the stock ; it is the living fibres, and the living vessels of both; and unless both be alive, the process must fail, living juices would do no good. Secondly', though the juices did so unite or glue together the branches of a tree, that were no proof of the juices being alive; but only that good juices, whether alive or not alive, were necessary to the process. Any man who affirms that in surgical operations it is the blood, " that by a contiguous sympathy unites the parts," should have supported his assertion by this further argument, that without blood they will not unite. Prove to me only that fresh cut parts are not alive, and cannot naturally unite without OF THE BLOOD. 51 the assistance of some foreign power, and then I will acknow- ledge willingly that they are altogether beholden to the inter- mediation of the blood, with its living principle, and sympathy of contiguity. But it is very singular, that any person, even the least in- structed in forms of reasoning, should have advanced this as any proof of living principle in the blood, " that mortification immediately follows where the circulation is cut off;" for this proves merely, that the blood is one of many stimuli, by which the system is supported, in so much, that each limb is affected just as the whole body would be ; and whether you stop the blood, which is one stimulus, or take away its heat, which is the stimulus next in power to the blood, the limb will equal- ly die. To say that the life is in the blood, because the biood being taken away, the limb dies, or because an animal may be bled till it dies ; what is this but to jumble all distinction of cause and effect ? The water, no doubt, is the life of the mill, and the plough-horse is the very life of the plough ; for the mill and the plough are dead the moment that the horse is gone or the water fails. Lastly, we are told " that it is by the contiguous sympathy of the blood and body both being alive," that they both work upon each other mutually : but is it not very strange for any physiologist to forget, that the blood is at least in part a foreign body, that it must be continually impregnated with air, that it is neither its original constitution, nor these presumed sympa- thies that make it vital blood, that it becomes vital blood only by exposure to air, and that if this foreign principle be not continually added, the solids are not wrought upon by the blood ? The natural difficulties of this doctrine are very great; for it seems to be against all the laws of nature that any fluid should be endowed with life. A fluid is a body whose parti- cles often are not homogeneous, have no stable connection with each other, change their place by motion, change their nature by chemical attractions and new arrangements; a body which can have no perfect character, no permanent nature, no living powers connected with it. But the definition of a solid is the reverse of this : a solid among every kind of metals, earths, or fossils, is recognized by its peculiar form and arrangement of parts : and in the animal body, the arrangement of particles gives the permanent unchanging character of each part; and in the muscles, for example, or in the nerves, where feeling and irritability chiefly reside, the form and mechanism of the solid is in each most peculiar, and is always the same. 52 OF THE BLOOD. What is this blood that it should begin life and support it, and distribute it through all the system ? Is it not a fluid which varies every hour, now richer, now poorer, now loaded with salts, now drowned in serum, now much, now sparingly sup- plied with air, now darker coloured, now red, now fully sup- plied with chyle, and now starved of its usual supply ? Is it not lost in astonishing quantities in haemorrhagies, and drawn veiy freely from our veins upon the slightest disease ? That such qualities are consistent with life in the blood, is what I cannot believe. But I can most easily imagine how the system, having by successive operations converted the food into chyle, the chyle into blood, and fashioned the nutritious part of the blood into various solids ; these new solids may partake of the vitality of all the parts to which they7 are applied, and to which they have been assimilated by so peculiar and so slow a process. The question is plainly this : shall we follow the general laws of the system, such as physiology acknowledges ? or shall we admit an absurd novelty without proof? Shall we allow ofthe simple accident of coagulation (an accident common to dead fluids) as a proof of life ? or shall we forget those stupendous proofs of the irritability residing in the heart, muscles, and other forms of our living solids, and which is the source of all the various actions of the body ? Shall we forget that polypi, worms, insects, the bloodless parts of fishes, the uncoloured parts of the human body-, even plants almost inanimate, all par- take of life, without having red blood in their system, or ha- ving it restricted to the central parts ? All these have life and vitality, but where is their blood ? In short, the question plainly resolves itself into this, shall we have two living parts, fluid and solid ; two agents acting on each other ? or shall we follow the common law of the oeconomy, call the one an exciting power, while the other receives that excitement, being alive only that it may feel and act according to the degree in which it is moved ? Shall we have the blood communicating life to all the body ? or the body only alive, and the blood, like various other excitements, acting upon it with those powers which it is continually acquiring, without acquiring along with them anyr share of life ? But Mr. Hunter, ill contented with his doctrine' himself, he even who began with giving to the blood a vital principle, and calling it the former of new parts, and the substance whence the living solid derives its life, hatches a new doctrine out of the confusion of the first; takes from the blood all those high privileges in the system which he had so freely bestowed upoii OF THE BLOOD. 53 it, and gives them in full perpetuity to a new principle, a prin- cipium vitas diffusge, which he announces thus : " I would consider that something similar to the substance of the brain is diffused through the body, and even contained in the blood; and between this (viz. the matter diffused in the blood) and the brain the communication is kept up by nerves." This matter he does not like to define, but he must name it; and having observed, as others have done, that a mouthful Of nonsense sounds infinitely better in Latin than in our mother tongue, he calls it the " Materia vitas diffusa.—Concerning this diffused principle of life he tells us, that every part of an animal has its due proportion ; it unites all the bodyr into one ; " it is as it were diffused through the whole solids and fluids, making a necessary constituent part of them, and forming with them a perfect whole."—The terms in which this doctrine is proposed are hardly more intelligible than those in which he argues about the life of the blood ; the matter itself, resembling the substance of the brain, is supposed ! the manner of its union with the blood, is supposed ! its connection at once with the fluids, and with the living solids, is supposed ! the sort, of a manner, in which this matter harmonizes the whole, is sup- posed ! and now the coagulation, and life of the blood, is no longer an effort ofthe life ofthe blood, but ofthe materia vitae diffusa ; and the blood does not form the solids, the blood no longer communicates life to the solids, but the blood and the solids are both at once animated by this diffused principle of LIFE. No one need triumph over a doctrine which thus falls by its own weight; but this must not be forgotten, that the doctrine ofthe life ofthe blood leads to a mean contracted narrow view, not merely of this but of higher subjects. Plants have active and irritable fibres ; by the most curious actions they drink in water ; water alone they can convert, by the most simple mechanism, into the most delicate perfumes, into delicious fruits, or into terrible poisons. " There stands," says Bhimenbach, " a hyacinth before me ; generations of these flowers, of which this is the last, have grown there suc- cessively, touching the surface merely of a little water ;" but shall Mr. Hunter persuade me that this water is alive ? " vel hyacynthi me monent."* I think I may safely conclude, that these theorists have done the science no good ; themselves no honour ; and us no kind of benefit, unless it be an advantage to know that by none of these ways can we arrive at a knowledge ofthe blood. " Page 17. 54 OF THE BLOOD. QUALITIES OF THE BLOOD. Blood is a fluid of a rich and beautiful colour ; it is vermi- lion-coloured in the arteries, strong purple in the veins, and black, or almost so, at the right side ofthe heart; it feels thick and unctuous betwixt the fingers, is of a slighdy saline taste, is various in various parts ofthe body, in the heart or at the cen- tre of the circulation different from what it is in the glands, ex- cretories, and all the extremities of the body ; different in the liver, among the intestines, in the cheeks, and lips, in the reser- voir or sinuses of the head and womb. In various individuals, but much more in different animals, it varies with their func- tions and manner of life ; it is more or less perfect in animals, in birds, in fishes, in insects ; it is thick or thin ; has gross particles or small; is red or pale ; hot or cold ; according to the creature's life : and from this last variety, viz. of the man- ner of life, comes our division of animals into those of hot and cold blood. It is by the most simple and natural methods that we exa- mine the blood; since almost spontaneously it resolves itself into three parts ; the crassamentum, the serum, and the red globules ; for in a cup of blood the crassamentum, or clot, the hepar sanguineum, as it was called long ago, floats in the serum ; the red globules are engaged in this clot, and give it colour; the serum may be poured off, the coagulum may be washed till it is freed of the red parts of the blood ; and then the red particles are found in the water with which the coagu- lum was washed, and the coagulum remains upon the strain- er, litde reduced in size, pure and white, the gluten or fibrous part of the blood. Or we may separate this part by a method which Ruysch first taught us ; we may, while the blood is con- gealing, stir it with a bunch of rods, when the pure and colour- less gluten gathers upon the rods and the serum, with the red particles suspended in it, remains behind. OF THE RED GLOBULES. The red globules, as Ave have observed, are not universal; yet in all creatures, even in colourless insects, there seem to be formal particles in the blood ; in white insects, they are white, in green insects they are green, in most insects they are trans- parent. The red globules of the human blood are easily seen ; they are best examined with a simple lens, the globules being dilut- OF THE BLOOD. 55 ed in serum, and laid upon an inclined plane, not in water which dissolves them quickly, but in serum, which has the property of preserving their globular form—The size of the particles of the blood varies in various creatures ; in the foetus they are bigger than in a grown animal; and although Leeu- wenhoek thought it essential to his doctrine, to say, that they were alike in all creatures, we know beyond a doubt that there are in respect to the size of the animals the strangest reverses. The Skate has red globules much larger, and the ox has globules much smaller, than those of a man. Fish have large globules, serpents smaller ones, and Man smaller still. In Man the diameter of each globule is much less than the three thousandth part of an inch. There is in the effect of lenses, or in the nature of these globules, some strange refraction, by which there seems a darkness in the centre of each globule, and thence a deception which has been universal; so that no single description has tallied with that which went before. Leeuwenhoek believed that he saw them consisting each of six well compacted smaller globules : Hewson believed that they were bladders, which had within them some central body, loose and moveable ; that often the central part might be seen rolling in its bag; and that sometimes the bladder was shrunk and shrivelled around the central body, and could, by putting a drop of water upon it, be plumped up again. The Abbe Torre examined them with simple lenses too ; but they magnified so highly, that from this cause all his noisy mistake has arisen; for he used not ground lenses, but small sphericles of glass formed by drop- ping melted glass into water : theyT magnified so much, that to him the central spot appeared much darker ; he said that these were not globules, but rings. He sent his sphericles of glass and his observations from Italy, his own country, to our Royal Society ; and for a long while, though nobody could see them, still the public were annoyed by Abbe Torre's rings. Falconer, with all the zeal of a friend, published Hewson's discoveries after he was dead ; lamenting, as we all must do, the loss of a promising young man. Falconer thought he saw these globules, not as spheres but as flattened spheres ; lie thought he saw them often as they rolled down the inclined plane upon which he placed them, turning their edges, their sides, their faces, towards the eye ; he even compared their flatness with that of a coin. Many authors have conjectured that these globules are compressed when they come into nar- row ,passages, and expand again when they get into wider arteries. This Reichell says he has seen, and Blumenbach believes ; but Blumenbach, less easy of belief with regard to 56 OF THE BLOOD. all these strange forms ascribed to the particles of the blood, pronounces his dissent in plain terms. " They appear," says he, " to my eye no other than simple globules, apparently of mucus : that lenticular or oval form which authors speak of, I have not seen." The following are their chief properties with regard to the rest of the blood. When blood stands, they fall to the bottom, because they are heavier than the other parts of the blood; and although the gluten entangles them while it is forming, still it is to be noticed that the cake is always redder at the bottom; and when by weakness or disease this coagulation is very slow, some globules escape the grasp of the coaguhim, and the serum is tinged with red, and the cake, though coloured at the bottom, is white at the top, or has the buffy coat. Their form they preserve only while in the blood, and seem to be supported more by the qualities of the serum than by their own properties ; for if mixed with water, they mix easily, and to- tally dissolve ; the wrater is red, but the globules are gone ; when we mean to preserve their forms for experiment, we must keep them in serum, or must make an artificial serum by impregnating water with salts. Their quantity, in regard to the whole mass, varies so, that the appearance of the blood is a real index of health or disease : in disease and weakness, the blood is poor and colourless ; in health and strength, it is rich and florid ; by labour, red particles may7 be accumulated in a wonderful degree : in hard working men they abound ; they may be accumulated by exercise into particular parts, as in the wings of Moorfowl or Pigeons, and in the legs'of com- mon Hens. In short, the red globules are numerous in health; in large and strong creatures ; and in the centre of the system, where they often circulate when (as in fishes) all the flesh is colourless ; in psuch a system, particular glands only, or viscera, as the liver, stomach, or spleen, are coloured with blood, and but a small proportion circulates in the great ves- sels round the heart. The redness of these particles is a peculiarity for which we know no meaning nor cause. The greatest physiologists have ascribed it to the iron of the blood ; but when we reflect how many various colours iron gives in its various states ; when we reflect, that the unknown cause which gives colour to the iron may give colour to the blood ; when we reflect that of this crocus of iron we can hardly procure one poor grain from four hundred grains of these red particles of the blood ;—we can- not but be conscious that this peculiarity is not yet explained. OF THE BLOOD. 57 COAGULABLE LYMPH. The coagulable part, the cake which is left when we wash away the red globules, is by far the most important part of the blood, the most universally diffused in the animal system, the most necessary for the supply and growth of parts. It forms all the solids, and in its properties resembles them most curi- ously ; for this cake, when washed, is. white, insipid, ex- tremely tenacious, and very fibrous ; can be drawn out greatly; and it is the coagulation of this part that makes the long fibrous strings which we find in the tub when bleeding a patient in the foot in very hot water. Being slighdy dried, it shrinks into a substance like parchment; being hardened by heat, it becomes like a piece of horn or bone; when burnt, it shrinks and crackles, with a very fetid smell, like the burning of feathers, wool, flesh, or any other animal substance; by which we know it to be the part of the blood which is the most perfecdy animalized, and the most ready to be assimilated with the living solids. When distilled, it gives ammoniacal salt and alkaline water, and a very thick heavy fetid oil, and much mephitis, which are the marks of the most perfect ani- mal nature ; and after burning it, the residuum is a phosphate of lime, or, in other words, the earth of bones. Its peculiar properties, as it appears in the blood, are few; its relation to the body is very surprising; how the body ac- quires, and how it applies, this most important part of the blood, we shall next explain. There is no part of our food which does not contain this gluten in a large proportion. With regard to animal food, mis is to be remembered, that except the fat and the earth of bones (which is in a wonderfully small proportion), the whole is gluten. A piece of animal food we can first wash clear of its blood till it be colourless, and then boil with a strong heat till it is converted into jelly merely. Eggs contain an animal gluten separated and entirely formed; the final use of which is to enter into the intestines of the chick, and nourish it. Milk contains in its curdy part a perfect gluten, which is easily se- parated, and when perfect coagulates with acids like blood. Oysters, shell-fish, fishes of all kinds, are so entirely formed of gluten, that many of them can be boiled down to a perfect jelly. With regard to our vegetable food, this is to be re- membered, that much of it is already formed into gluten, and is ready to be assimilated into an animal nature. If we knead up flour with cold water into a cake, the washing of that cake resembles the process of washing a coagulum of blood; for Vol. II. H 58 OF THE BLOOD. while we hold it in our hand, and pour cold water upon it, the water as it runs off carries along with it a white amylaceous matter, which is starch; along with this there is much sac- charine and mucilaginous matter; but the most dense and solid part of the cake remains in the hand. This is the gluten of the vegetable left alone, just as the gluten of the animal is washed pure of the red blood; and this vegetable gluten is very tough, so that the whole cake may be drawn out into one long string. It is so tenacious and so hard when dry, that it has been long used as a cement; and it so precisely resembles the animal gluten, that, put them together, and you can see no distinction. It shrinks also with heat, and is converted into a substance like parchment or horn. It first melts with heat, and then burns like feathers or hair; and by distillation it gives only alkaline ammoniacal salts and fetid oils ; it wants no mark of perfect analogy with our animal gluten, and we can be at no loss to think whence all our necessary supplies arise: and flour, though it is the richest, in this highly nutritious part scarcely exceeds corn, barley, potatoes, pease, and beans, and all those vegetables called legumina, upon which chiefly we depend for bread, or a substitute for bread. These do not, indeed, contain this vegeto-animal matter direcdy or entirely formed; but they consist of a jelly analogous to all the white or gelatinous parts of the human body ; as vegetable jelly, it has a vegetable character, it ferments and becomes acid; while animal jelly, as belonging to the animal body, has other characters, it becomes putrid, and affords alkalis only: but how easy this conversion must be, I need hardly suggest, What passes within the animal body, or how this gluten is directly applied, we never can know ; but we see how all the body is composed of gluten, and no analysis of any single part has ever disappointed us. A muscle being squeezed, and thoroughly cleansed of blood, washed in spirits of wine, and again cleaned, is seen plainly to be but a peculiar form of coa- gulable lymph. An anatomical preparation washed, and pu- rified as it is, consists of mere lymph retaining its primitive shape. A bone being infused in any mineral acid, or in vine- gar, its earthy parts are dissolved even to its centre ; it be- comes soft and flexible, still retains the form of a bone ; but what remains is merely coagulable lymph. And though Four- croy is certainly right in saying the coagulable lymph is that part upon which nature fixes irritability or the contractile power, he should have added, " but this gluten is moreover in the animal body the basis of every part which possesses life ;1' it constitutes, in truth, no less than nine tenths of the solids of the whole body. The membranes, ligaments, tendons, pe- OF THE BLOOD. 59 riosteums, and all the white parts of the animal body, consist entirely of this ; and it is the business of cookery to boil them down into this jelly. It is this fibrous part, then, which is secreted by the vessels for repairing all the wastes and all the accidents of the body; when a muscle is wasted by violent action, or by fevers, or by long confinement is absorbed, glu- ten is secreted to fill it up ; when a bone is broken, much of this jelly is deposited in a bed for vessels to stretch into, and a new bone is quickly formed ; when soft parts are cut, gluten is poured out betwixt them ; when viscera are inflamed, pure gluten, white, and membranaceous-like, is poured out be- twixt them ; when the uterus is to be prepared for receiving the impregnated ovum, gluten is poured out into the womb ; and in all these cases it is the foundation of a union with the sur- rounding parts. In short, this gluten forms, nourishes, sup- ports, restores the parts of the animal body; but far from considering it either simply, or along with red globules, as containing the principle of life, I find it as perfect in dead vegetables a6 in living animals ; and view it only as that parti cular form of matter which nature has wisely appointed for our chief nourishment and support.* THE SERUM. The serum is the thinnest and most fluid part of the blood, which dilutes the other parts, and receives all those extraneous substances which often circulate in our system : this must be kept in view when its properties are to be told, for though it so • It will easily be perceived, that here I choose to sink, in this general descrip- tion, all those lesser distinctions which are so imperfectly proved. Distinctions betwixt the gluten and the albumen or serum in animals, or betwixt the vegeto- animal gluten and the starch in vegetables, I hold to be very vain; these are but various stages of the same product; what is-less perfect in the albumen, is more perfect in the gluten ; and a little more or a little less of the oxygene or acidify- ing principle, makes perhaps all the difference : these parts, as they are more or less perfect, contain more or less of this principle, and are more or less ready to congeal ; both kinds of jelly, when treated with nitrous acid, give out azotic gas; azotic gas, united with hydrogene gas, forms the volatile alkali; and the giving out of this azotic gas to nitrous acid, or the forming of the volatile alkali in the act of putrefying, are the chief tests by which animal matter is known. Then to make formal distinctions betwixt the tendinous and the fleshy parts of animals, and to call the first gelatinous and the latter glutinous parts, as formed of the proper gluten, seems very vain ; and not less so to make essential distinctions betwixt the gelatinous parts of vegetables and those of animals, since the slight change of proportion of azot or oxygene must make the whole difference when these vegetable jellies are assumed into the living system and completely analysed. 60 OF THE BLOOD. exactly resembles the white of an egg, that some have in com- paring the two, written whole pamphlets upon the subject, and named it the Albuminous Fluid, although it coagulates like gluten, although it putrefies like flesh, although it gives out up- on distillation ammonia and a black and fetid oil ; yet it is most natural that along with these it should contain also some foreign bodies, as a saccharine or extractive matter, belonging to vegetables, and some proportion of the oxalic, malic, or other v^ getable acids. Serum or the albuminous fluid is like whey, of a yellowish, or rather greenish colour, of an unctuous or slippery feeling among the fingers ; it is slightly saline, and its salt is chiefly of an alkaline nature ; it contains soda completely formed, by which it turns vegetable reds to green ; it coagulates firmly with a heat much lower than that which makes it boil: being dropped into hot water, it coagulates as it falls ; by 150 de- grees of heat it coagulates into an albumen like the white of an egg ; but if gradually evaporated, the cake which remains is quite similar to the gluten ofthe blood. It is upon this alkali that the fluidity of tlie serum seems to depend; spirits of wine do indeed seem to congeal the blood, but it is not a true coagu- lation, since it depends merely on the avidity of spirits for wa- ter, by which the spirit of wine takes the water to itself, thick- ens the serum, and makes the whole turbid ; but acids produce a true coagulation by seizing that alkali on which the fluidity truly depends. To say that lime coagulates the serum, but melts down the lymph, is by no means to establish a rational distinction be- twixt the cake of gluten and this gluten which the serum holds dissolved: till some decisive difference be proved important to the whole system, I cannot but believe that they are one ; nor can I, when I see the water which washes the coagulum impregnated with gluten, believe that there is any difference. Yet we need not wonder that such ignorant unmeaning dis- tinctions as these shotdd have been made, since the halitus of the blood, or that vapour which rises from it while it cools, was examined with a most ludicrous affectation of accuracy, though it is merely water alone, having a slightly urinous smell, from its connection with the blood. The serum dilutes the whole mass, and no other fluid can we find so fit to hold in solution a proportion of gluten, or so fit to support the form ofthe red globules, or so fit to pass easi- ly and smoothly along all the delicate vessels, without exuding through the pores. For in truth it is with the serum as with our injections ; if we inject simple water, it exudes at every OF THE BLOOD. 61 pore, and the whole cavities are filled, and the whole body- swelled and bloated ; but when we mix size, i. e. gluten, com- mon glue, with our water, it penetrates to the extremest parts, yet still keeps in the channels of the arteries, and often returns by the veins. The whole fabric ofthe blood should now be exposed in one continued view, consisting of three distinct parts, whose uses are these: First, we see the serum diluting and tempering the whole, preserving its lubricous and fluid form, containing and dissol- ving all foreign matters which may have got access to the sys- tem, and running them off by various excretories ; for the se- cretions are chiefly from the serum, containing gluten enough to support the tenuity of the blood, salt enough to keep the red globules in their form, and conveying also a sufficiency of lymph into the most delicate and bloodless parts of the body : and this above all is a most singular property of the serum, that it admits freely the air to pass through and impregnate the blood; for when the coagulum of the blood is drowned deep in its se- rum, if turned up and exposed to air it reddens ; which, if oil, mucilage, water, or any other fluid, be substituted instead of serum, it will not do. Next, we see the red globules of large diameter, but in quan- tity very small, i. e. in proportion to the whole system ; of large diameters, that they may not go into the very minute vessels, and in small quantities, because they are accumulated round the heart, and in the greater vessels. And, lasdy, the gluten is the most important part of the blood; that which, being dissolved in the serum, pervades even the most exquisite vessels of the system ; the part from which all our solids are formed, and into which all our solids, and even fluids, can be resolved. But allowing for the vari- ous proportions of the water which dilutes the serum and the red globules (whose proportion to the fluids cannot be named it is so small,) and some saccharine or extractive matter which is in the serum ofthe blood—what is there except gluten in all the animal system ? Serum, coagulum, flesh, tendons, liga- ments, bones, all are composed of it; and when gluten is thus united to the solids, forming with them one individual body, it acquires new powers, and is indeed alive. This analysis of the blood contains the analysis of almost all the humours or secretions of the body. Observe how nearly the urine resembles the serum, indeed the urine, like the serum, preserves the peculiar form of the red globules, and sweat is but a serum loaded with salts ; observe how little saliva dfl- 62 OF THE BLOOD. fers from the serum ; observe how perfectly the serum resem- bles milk, since mixing serum with water produces a milky fluid, that is, a fluid which gathers cream on the top, and coa- gulates with acids and heat. The water of dropsies is purely serum ; the mucus of hollow passages is little else than inspis- sated serum ; the bile itself is said to be imitated by keeping putrid blood. In short, it is obvious that on the coagulable lymph depend all the internal secretions, u e. for supplying the w-astes of the system, for enabling it to grow, for repairing bruised or cut flesh, or broken bones ; that on the serum which dilutes the blood, and contains all such foreign bodies as might be injurious to the system, all the excretions, as urine, sweat, saliva, tears, &c. &c. depend.* I have said, " that the blood is a fluid of a rich and beautiful colour ; vermilion-coloured in the arteries, strong purple in the veins, and black, or almost so, at the right side of the heart." When we open the thorax of a living Dog, the lungs collapse, the neart soon ceases to play, the Dog languishes, expires, is revived again when we blow up its lungs :—then begins again the motion of the heart, the black blood of the right auricle is driven into the lungs ; the blood goes round to the left side of the heart of a florid red ; and this purple blood of the veins, the vermilion blood of the arteries, the change happening so plainly from access of air, is a phenomenon of the most inter- esting nature, and binds us to look into the doctrines of che- mistry for the solution of a phenomenon to which there is in all the animal economy nothing equal. It is the study of air and aerial fluids that has brought to light all the beautiful discoveries of which modern chemistry can boast. The simplicity of the facts in chemistry, the cor- rectness of the reasoning, the grandeur which now the whole science assumes, is very pleasing; and makes us not without hope, that by this science, all others, and ours in an especial manner, may be improved ; for the action of vessels will do much in forming and changing our fluids : all the rest is che- mistry alone. * When the blood and solids of animal bodies come to be resolved in their ulti- mate parts, we find a variety of combinations which belongs to another science, and which in this place it were tedious to explain. But still there is one great dis- tinction betwixt animal and vegetable matter, which should not be left unnoticed. Animal matters always, when dissolved by nature, fall into a putrid state, and give only volatile alkali. Vegetables, when they dissolve, fall into fermentation, and produce acids or wine; not that alkalies are necessarily contained in their formal state in the animal body, but that the animal body contains much mephitis or basis of nitrous air, which, combining with the inflammable air afforded by decompos- ed water or by their oils, forms the volatile alkali. OF THE BLOOD. 63 The older chemists were coarse in their methods, bold in their conjectures, in theory easily satisfied with any thing which others would receive. They condescended to repeat incessant- ly the same unvarying process over each article of the materia medica ; and among hundreds of medicinal plants which they had thus analysed, they could find no variety of principles, nor any other variety of parts and names than those of phlegm, and oil, and alkali, and acid, and sulphur^and coal. By this they disburthened their consciences of all they knew, pleased their scholars, and set the physicians to work, forming magnificent theories of salts, sulphurs, and oils ; for such has ever been the connection of chemistry with physiology, that good or bad, they have still gone hand in hand. The older chemists thought that they had arrived at the pure elements while they were working grossly among the grosser parts of bodies. They could know nothing of the aerial forms of bodies, for they allowed these parts to escape. When their subjects, by extreme force of heat, rose upwards in the form of air, no further investigation was attempted; it was supposed that the subject of their operation was consumed, annihilated, wasted into air, and quite gone. When they thus stopped at airs, they stopped where only their analysis became interesting or simple ; stopping where they stopped, among their oils and sulphurs, they made their science a mere rhapsody of words. Philosophy they considered so little, as not to know that the lightest air is really a heavy body, and that with weight and substance other properties must be presumed. Modern chemistry begins by assuring us, that these airs are often the densest bodies in the rarest forms, that airs are as material, as manifest to the senses, as fairly subject to our ope- rations, as the dense bodies from which they are produced : that it is heat alone (a substance which irresistibly forces its way into all bodies) that converts any substance into the aerial form: that some bodies require for their fluidity merely the heat ofthe atmosphere, and so cannot appear on this planet m any solid form : that others require some new principle to be added, in order to give them the gaseous or aerial form : that others require very intense heat to force them into this state; but that all aerial fluids arise, or must be presunaed to arise, from some solid body or basis, which solid basis is dilated by- heat into an air. The solid basis of some airs can be made ap- parent, as of fixed air which proceeds from charcoal; others, as pure air, or azotic air (the great constituents of our atmos- phere,) cannot be produced to view into any solid form. But those airs which cannot be exhibited in any solid form, can vet be so combined with other bodies as to increase their weight. 64 OF THE BLOOD. and give them qualities of a very peculiar nature; and these airs can be alternately combined with a body and abstracted again, adding or abstracting from its weight and chemical pro- perties, not only in a perceptible, but in a wonderful degree ; so that these abstractions and combinations constitute some of the most general and important facts. When the old chemists, then, neglected to examine these airs, they refrained from ex- amining the last elements of bodies at the very moment in which they came within their power. That these must be the most material and important facts in all the science, it is easy to explain ; for chemistry, ever since it has been a science, has rested upon one single point. There are certain great operations in chemistry which we perceive to have the strictest analogy with each other, of rather to be the same ; the operations are, the combustion of inflammable bo- dies, the respiration of animals, the calcination of metals ; and whatever theory explains one explains the whole. The older chemists observed, that when they burnt an inflammable body, the surrounding air was contaminated, the substance itself was annihilated, nothing remained of its former existence but the foul air ; and they supposed that this inflammable body consist- ed of a pure inflammable principle, which was the substance which spoiled the air, lessening its bulk, and making it unfit for supporting any longer either combustion or animal life.— When an animal breathed in confined air, they found the phe- nomenon still the same ; the animal contaminated the air, and expired itself; left the air unfit for burning or breathing, load- ed, as they supposed, with the inflammable principle. When they calcined a metal (which is done merely by heating the me- tal and exposing it to air,) they found, as in these other opera- tions, the air contaminated, the metal losing its metallic lustre, ductility, and all the marks of a metal,—acquiring (in certain examples) new qualities, like those of some mineral acid, and becoming of course a most caustic drug : but above all, they uniformly observed the metal to increase in weight. To account for all these discordant changes was the most difficult part of all: it was indeed easy to say, that combustion was the giving out of an inflammable principle to the air ; and to say concerning respiration, that it was the business of the air to take away continually the superabundant phlogiston of the blood ; but how a metal should pass from a mild to a most acrimonious and caustic state ; and above all, how by the loss of its inflammable principle it should not lose in weight, but in- crease in weight! This was the Gordian knot which they had to untie, and which they cut lustily, betaking themselves, in defiance of all philosophy, to the absurd project of a principle Ot THE BLOOD. 65 of absolute lightness. They all agreed to call the phlogistic principle a principle of absolute levity; and thus their doctrine stood for many years, viz. that when phlogiston, or inflamma- ble principle, was added to the calx of any metal, as to red lead, by roasting it with any inflammable body—the metallic lustre, tenacity, ductility, were restored, and the metal be- came lighter withal, because it now had within it the principle of levity. But that when by heat and air it was calcined, this principle was driven out, and then the metallic lustre, tenacity, ductility, &c. were lost by the absence of the inflammable prin- ciple upon which they all depended ; but the weight of it was increased, for the principle of levity was gone. This is the brief abstract of the theory to which the very best chemists have addicted themselves down to the present times. But the chief perfection of modern chemistry is, that its apparatus is so perfect, that it can employ exactly a certain quantity of air in calcining a metal; it can collect that air again to the twentieth part of a grain ; it can prove whether the me- tal has really been giving out any inflammable principle to the air, or whether it has received matter from the air, and how much expressly it has gained or lost. Modern chemistry proves to us, that it is not the loss of any principle that endows a metal, for example, with negative powers; but the direct acquisition of a new principle, which endows it with positive powers. Thus if you take a quantity of mercury, and expose il slowly, that is, for a long time to heat and air, the following changes take place ; it gradually loses its metallic lustre, the upper part of it assumes first a y^ellow and then a red colour, small red particles are seen floating on the surface of the mer- cury ; and these are the mercurius precipitatus per se, a most acrid calx of mercury. If, first, you estimate how much air has been expended during the process, you find that the weight of the mercury is increased in exact proportion ; if you put that calx into a gun-barrel, put the gun-barrel into the fire, and by mere force of heat drive out this air, you find the quantity of air exactly equivalent to the quantity expended in the process ; you find the metal grow lighter, and recover its metallic qualities and lustre in proportion as the air is expelled. In short, we find the metal heavier when combined with air, lighter when the air is driven out.; we find it having the qua- lities of a metal when uncombined with air, when combined with air having the qualities of a calx : then plainly this caustic form of the metal is not a negative quality, it is a posi- tive one, proceeding from the infusion of this new principle from the air. By such proofs as these chemistry has explained, in a most Vol. II. I 66 OF THE BLOOD." philosophical way, how all these phlogistic processes, as they were called, depend, not on the abstraction of phlogiston, but on the addition of a new principle : that they all arise from one positive power, that the same principle gives life to fuel, hea- viness (and other effects of calcination) to metals, acidity to acids, and redness to the blood. These are all performed by one power ; they are all essentially one process ; they are ail effected by the communication of one sole principle, viz. the basis of pure air. Upon our atmosphere and its surprising harmony with all parts of nature ; with animal and vegetable life j with water, metals, acids, and all the solid bodies into which it enters—- much more depends than it is easy to conceive. Could we have supposed that it was the cause, not merely of life in all living creatures, but almost the cause of all the properties that reside in the most solid forms ? Could we have supposed that the air rendered heavy bodies heavier, changed metals into caustic earths, converted many bodies into acids, changed in- flammable air into the pure element of water, which at least we have hitherto conceived to be pure ? Yet, if there be one word of truth in chemistry, all this is true. The atmosphere contains various gases or airs ; but one only, viz. vital air, is useful to respiration, combustion, and animal life ; that purer air must, like every other, arise from some solid basis : that basis cannot be shown in any substantial form, but it can be combined with many various bodies, so as to give them an increased weight and new qualities: and thence we presume to say, whenever we see a body, by such a pro- cess, acquiring such qualities, that it acquires them by absorb- ing the basis of pure air ; for pure air is nothing but this pre- sumed basis dilated into the form of air by heat ; and when it combines with any body, it gives out its heat; so that in all these processes heat is produced. And although inflammable bodies, metals, acids, and animal blood, seem very distinct from each other ; although combustion, breathing, calcination, and the forming of acids, are processes seemingiyr very unlike ; yet they are in all their essential points the same, viz. a change of qualities and a production of heat in consequence of the absorption of pure air. First, when an inflammable body is burnt or consumed by fire, the basis of pure air is combining with the combustible bod)'; the air is entering into a new combination, and there- fore must give out its heat; it combines rapidly, gives out its heat rapidly, is wasted; the inflammable body burns and seems to be consumed : but if we catch that air which escapes from the inflammable body, we find it to be equal exacdy to OF THE BLOOD. 67 the whole weight ofthe air and of the burning body that have been consumed ; and this air consists of two parts, viz. ofthe substance which was burnt, and of the basis of pure air. Thus, for example, when we burn charcoal or carbon, the whole substance of it, weight for weight, is converted into an air, which is called fixed or fixable air ; the same which is dis- charged from stoves, the same also which is found in pits, the same which oozes through the ground in the Grotto del Cane, the same which floats upon the surface of fermenting vats, and which is so much heavier than common air that it can be taken out from a vat in basons, and poured from dish to dish. Combustion, then, is a process which consists in the rapid as- sumption ofthe basis of pure air, and a consequent conversion of the burning body into an air endowed with peculiar quali- ties and powers. If, then, the oxygenation of the blood be a process like this, it must differ chiefly in degree ; it might in certain circum- stances become too rapid, and resemble an actual combustion ; and so in certain circumstances it does, for our atmosphere is so tempered that no more than 27 parts out of 100 consist of pure air; the rest is food for vegetables, but not fit to maintain flame or animal life. This is the reason that even burning as well as breathing are slow processes, and that an animal, if made to breathe pure air, or vital air as it is called, gets the basis of air too rapidly united to its system, is consumed and inflamed quickly, and dies. Secondly, the process of calcination is the same in all metals ; it also is an assumption of the pure air, or rather of its basis, with a change of qualities and increase of weight: if you calcine lead slowly, it becomes first yellow, then orange, then red; it becomes heavier, so that from 100 pounds of lead you have 110 pounds of litharge, or calx of lead: if you calcine mercury, it also becomes first yellow, then red, and much heavier than at first: if you distil any of these metals, you can by heat merely drive out the purest air from them ; they recover their brilliancy and grow lighter, because the basis of air is expelled. The basis of pure air is expelled, not in that solid form in which it was embodied by the calx, but being now combined with heat, it appears in the form of vital air ; the air is much purer than that of the atmosphere which was used in the process, because the metal absorbs or appropriates to itself nothing but the purest air, leaving the azotic or foul air behind : and finally, if you wish to see the harmony betwixt combustion and calcination, or to be assured that calcination is truly the burning of a metal, take some of this pure air, which is three times purer than the atmosphere, 68 OF THE BLOOD. and raises an intenser flame; plunge into it a piece of iron wire, which is made red-hot; and this wire (which would only have wasted or rusted into a calx in the common atmos- phere) will in the pure air burst out into a brilliant white flame, and burn entirely while it has svich air ; nay, some metals, as zinc, burn even in our common atmosphere with a most bril- liant flame. From this second process, must it not be presumed that the principle which gives an increase of weight and such singular properties to various metals, must have very interesting effects upon the blood ? Thirdly, it is from this principle also that all acids are form- ed ; and as oxyd is the Greek name for acid, the great La- voisier has thought fit to give a name to the basis of air, or that principle which is obvious only when operating in such processes as these. He adds to the Greek name for acid that verb which implies the generation of any substance ; he calls it thus oxygene, or the principle which generates acids. It were easy to show how truly this great point is supported by all the particular operations in chemistry ; it shall be sufficient to observe a few. When we burn sulphur in open air, it seems to be consumed; but when we burn it in close vessels, still giving a free access to air, we find it converted into an acid the most ponderous of all, weighing greatly more than the sul- phur from which it was procured. The operation is done in close vessels ; nothing can pass but what is known, and nothing is more certain than that the whole of this wonderful and rapid change is the mere effect of the sulphur, which is an acidifiable base, assuming the acidifying principle by which alone it can become an acid. Phosphorus being burnt in a close glass upon the point of a wire, the vital part of the atmosphere is consumed, the azotic air (which the ancients mistook for their phlogiston) remains, the whole phosphorus is changed into phosphoric acid, and the whole acid when weighed expressly equals the phosphorus which was burnt, and the air which was consumed along with it. Nay, arsenic, which is a metal, being calcined, is converted into a perfect acid. Thus we see, first, that calcination is a mere com- bustion, since it can be made so rapid as to be attended with heat and flame ; next we see that acidification is, like calcina- tion, attended with heat and flame, and an acquisition of weight and of properties like those of calces'. We see some metals converted into proper acids ; acids and metals mixing in qualities with each other ; acids and metals are both acidi- fiable bases, both are capable of receiving new and similar properties, by assuming into their composition the basis of OF THE BLOOD. 69 pure air ; and Li one single process the whole set of phenomena are exemplified, for in burning arsenic we have combustion, calcination, and generation of acid, all in one process, the pro- duct being named indifferently oxyd of arsenic, or white calx of arsenic* But if most acidifiable bases be thus forced by combination to forsake their solid and assume their aerial form, others more singular still are recalled from their aerial form, and con- densed into the fluid form of a strong acid. Thus azotic or mtrogene air, which forms the great bulk of our atmosphere, is converted by oxygenous or pure air into an acid form ;f it be- comes nitrous acid, nitric acid, nitrous air, strong or weak ac- cording to the various degrees of oxygenation communicated to it; and thus nitrous air, by its appetite for oxygene, and by its change of colour and its condensation, whenever it takes ox- ygene from the air, makes a eudiometer or measure for the pu- rity ofthe air; and, according to the purity ofthe atmosphere, more turbidness and more redness is produced in the nitrous air, and a greater loss of bulk, which may be marked on a scale. Thus are all acids formed of an acidifiable basis, various each according to its kind, on which the variety of acids depends ; but these all become acid by the addition of one uniform prin- ciple, viz. the basis of pure air, which is the cause of acidity in all bodies : and this third great fact in chemistry may well sug- gest to us a higher view of our present subject; for this prin- ciple, which bestows weight and causticity on metals, acidity on acid bases, and new properties on all it touches, must make similar, or at least important, changes on the blood, converting it into an oxyd or subacid ; and we may fairly begin our next general fact under the title of the oxydation or oxygenation of die blood. The oxydation of the blood makes a fact no less important in physiology than those are in chemistry ; for as there are va- rious marks of the influence of oxygene on the blood itself, mere are terrible proofs of its importance in the system, and how miserable the person is who has imperfect organs or an ill oxygenated blood. Nature, disregarding all occasional supplies, as by the ab- * It is necessary to add nitre to make it burn. The result is not directly an acid, but a neutral salt formed of the arsenical acid joined to the alkali of nitre; without the help of nitrous acid it is only an oxyd or imperfect acid; and-it is necessary to use the hyper-oxygenated muriatic acid for communicating to it a suf- ficiency of oxygene to constitute it a perfect acid. f A1 B. It is necessary to inclose them in one vessel, and to pass thc electric spark through them that they may unite. 70 OF THE BLOOD. sorption ofthe skin, the assimilation of aliments, &c. has ap- pointed one great organ for the oxygenation of the blood, viz. the lungs. In opening the breast of a living creature we best see the connection of respiration with the great system ; but it is out of the body that we can best understand its particular effects upon the blood. The most obvious effect of air is its heightening the colour ofthe blood. If we expose blood to fixed air, or azotic air, it continues dark ; these fluids communicate nothing, they have no effect on the colour ofthe blood : when we expose blood to atmospheric air, it assumes a florid colour ; for in the atmos- phere there is a hage proportion of oxy-gene gas : if, lasdy, we expose it to oxygene gas, the purest of all air, it grows extreme- ly florid ; and whenever it changes its colour, it is by absor- bing oxygene, for it reduces in the same proportion the quanti- ty of air ; what it absorbs is the oxygene or pure air, what it leaves is mephitis, unfit for combustion or animal life.* Blood when exposed to the air becomes red chiefly on the surface, it remains black beneath, but by turning up the clot to the air all the surfaces become red. If air be blown into a tied vein, the blood which was black in the vein becomes florid ; and when the air is pressed out again, it becomes black. If the air-pump be exhausted over a dish of blood, the blood be- comes dark in the vacuum : and it becomes florid when the air is allowed to rush in again. If you expose blood in a moist bladder, the blood is oxygenated through the walls of the blad- der ; which brings this experiment as close as may be to the phenomenon of blood oxygenated through the walls of the lungs. Though serum or milk be interposed, or urine, still the bloodis oxygenated, because these are perfect animal flu- ids ; but it is not oxyTgenated if oil, mucilage, or mere water, be interposed. When we open a Frog, or Newt,f or other amphibious crea- ture, we see a long and slender artery, accompanied by a slen- der vein, running from top to bottom along the whole surface of their lungs ; and while their heart continues to beat, we see this pulmonic arteiy black, the vein red, the lungs themselves most delicate and pellucid, like the swimming bladder of a fish: even in the extremities ofthe human system the blood of a vein * Mr. Beddocs, in his last Book, makes hydrocarbon as effectual in reddening the blood as oxygen air. What are we to think of this ? Is it a freak of nature, or of the author ? f See Chap. III. ©F THE BLOOD. 71 is dark, of an artery red ; so that surgeons distinguish venous and arterial hemorrhagies in this way. From these facts we may understand why the blood of the Womb, of sinuses, of varices, and of all stagnant veins, is so of- fensive and black ; and why that blood is so very pure and flor- id which is coughed up from the lungs. Is not the face livid in apoplexies or strangulations, in hanging or drowning, in fits of passion or of coughing, or in any accident which interrupts the lungs ? The face of a child during a paroyxsm of the hoo- ping cough, is it not completely black ? Is not the hand livid when the arm is compressed or tied up, and its blood prevent- ed from returning to the lungs and heart ? Are not tumours dark-coloured from dilated veins which return their blood too slowly ? Are not those mulberry marks which are born with us just small aneurisms full of ill oxygenated blood ?—Then this first effect of oxygenation is a reddening of the blood. The menstrual blood, the blood of ecchymosis (as in those who have been whipt,) the blood of aneurismal bags, are all black ; and the blood of varices is so very black, that the ancients said they were filled with atrabilis or black bile. The stripes inflicted on a soldier as a punishment are at first of the most lively red, but soon become black. The next effect of oxygenation is the endowing the blood with a peculiar stimulant power, by which it is continually operating upon the living solid : this is a power which it is con- tinually losing; which it is every moment giving up to the so- lids ; and which no other process but respiration can restore.— This stimulant power the blood gradually loses as it circulates round the body ; it is quite effete when it returns to the right side of the heart: the heart of a creature never moves, if we allow its lungs to lie collapsed ; but the heart returns to act the very instant that pure air is forced into the lungs, and so com- municated to the blood. This stimulant power is most of all apparent when we force a living creature to breathe nothing but the purest air; for oxygenated or vital air makes this pro- cess too rapid ; the pulse rises, the eyes become red and pro- minent, the creature seems drunk with the new stimulus, too great for its system. The universal heat of its body is gready increased, the eyes are turgid and red, and at last a sweat breaks forth all over it; and when dead, the lungs (it is said) are mortified or inflamed. But whatever the marks are, whether these signs of inflammation be really true, it is plain, since the creature dies, that pure air is fatal by a too rapid ox- ygenation of the blood. If, in our experiments upon a dyeing animal, we inflate t!,< lungs with mephitic air, the heart does not act; if we inflate its lungs with common air, the heart be- 72 OF THE BLOOD. gins to act; if we inflate its lungs with oxygene air, the heart is irritated to a still more powerful action. If we open the breast of a Frog and stop its breathing, we observe, first, its pulmonic blood florid, and the heart beating strongly: secondly, in half an hour the pulmonic blood has be- come dark, and the heart's motion has grown languid; in a little while the pulmonic blood becomes black, and the pulsa- tion of the heart ceases : and, lastly, the trachea of the Frog being untied, and the creature allowed to breathe again, the blood becomes florid, and the heart acts. OF THE HEAT OF THE BLOOD. The next effect of oxygene is said to be the communicating of heat to the lungs. But I suspect that if the small quantity of oxygene which can enter by the lungs does communicate heat, it must be not to the lungs, nor to the blood, but to the whole body through the medium of the blood. There are some who pretend to say, that when they draw in vital air, they feel a ge- nial warmth in the breast, diffusing itself over all the body; but it is easy to feel in this way, or any way, when a favourite doctrine is at stake, while those who know nothing about doc- trines breathe the vital air without any peculiar feeling which they can explain. There are many circumstances which make it hard to be- lieve that there is, in consequence of the oxydation of the blood, any7 remarkable generation of heat in the lungs. Oxydation of the blood, out of the body, is attended with no increase of heat, and yet we operate on a quantity of blood much greater than that which circulates through the lungs. We call this process not the oxygenation, but the oxydation ofthe blood, be- cause we are conscious that it is an imperfect process ; it is perfect, indeed, with regard to its ultimate object, viz. that of communicating oxygene to the whole body ; but as an assump- tion of the acidifying principle into the blood itself, we see it to be so imperfect, the union so slight betwixt the oxygene and the blood, that it parts with it very easily; the blood turns black again if its colour be not supported by the perpetual con- tact of air; it is so imperfect, that we put it in the lowest point of saturation, and call it an oxyd or imperfect acid ; and how far it may be below the denomination even of an oxyd we do not know. To suppose, but for a moment, that all the heat which warms the whole body emanates from the lungs, were a gross error in philosophy ; it were to suppose an accumulation of heat in the Of THE Blood* 73 lungs equal to this vast effect of heating the whole body* But were it so, we should feel a burning heat in the centre, a mor* tal coldness at the extremities, and marked differences in the heat of each part in proportion to its distance from the lungsi In fevers, we should feel only the intense heat of the centre j we should be distressed^ not with the heat in the soles of the feet or palms of the hands, or in the mouth and tongue ; we should feel only the heat of the lungs. When the limbs alone were cold, would the lungs warm them ? How could it warm them up to the right temperature without over-heating the whole body ? When a part were inflamed, how could the heat go from the lungs, particularly to that point, and rest there ? From the lungs the heat could not be regularly diffused ; for in almost all the Amphibise the lungs are far distant from the centre of the body, and could not communicate any degree of ,heat to the extremities without the greatest waste; they would, according to this theory, have lungs for crying with, if they pleased to cry, but by no means for distributing heat. Those who have been the chief supporters of this doctrine, viz* of animal heat emanating from the lungs, have established then* doctrines on very fantastical and absurd laws; not merely of chemical changes producing heat in the lungs, but of the blood acquiring a greater capacity for heat than those substances have from which the blood itself is formed. The blood is formed from flesh, milk, wheat, rye, barley, and various other foods : these are curiously measured; the degree of heat which they communicate to water is assumed as the truth of their absolute heat: the absolute heat of all kinds of food is declared to be greatly lower than that of the blood itself j and this accumulation of heat in the blood is taken as a sure proof, that in respiration much heat is deposited upon the blood, it having a greater appetite or capacity of heat. But concerning this doctrine, which in its philosophical a9 well as in its chemical part is now antiquated, it is allowable to Bay, more freely dian of almost any other, that its intricacies are its beauties ; that it is a hypothesis illustrated by experi- ments, which have no other tendency than " to make it look Well in the face ;" and which are made with such affectation of niceness as is completely ludicrous. The author pretends to measure, to the tenth part of a degree, the proportions of heat in v\ heat, barley, flesh, milk, &c. Airs he also measures, showing the various capacities for heat in the different kinds of air to the tenth part of a degree ; a thing much fitter for a magician than a philosopher to undertake ; and which Dr. Crawford has executed so ill, that we -ire teased, or rathef thoroughly exhausted, before we begin, with correcting mea- Vol. II. ^ 74 OF THE BLOOD. sures and instruments and settling data ; while each new edi- tion of the book on animal heat must be prefaced with new apologies, new confessions, new corrections, new calculations, unhinging so entirely the conclusions and calculations of for- mer copies of it, that we* find ourselves engaged, along with our instructor, in a wilderness of errors, from which we can have no hopes of being extricated. Oxydation is a process which had no place in Dr. Craw-1 ford's views ; he never conceived that it was the presence of oxygene, as a new principle, which gave colour, stimulant powers, coagulability, and all its most useful properties, to the blood ; but he believed that pure air, uniting with inflam- mable air in the lungs, formed fixed air; and this fixed air being incapable of containing the heat which it had while in the state of pure air, that heat was deposited, or, as it were, precipitated upon the blood* He maintains, that there are of inflammable air two kinds ; one capable of forming water, another of forming fixed air ; but fixed air, derived from in- flammable gas of any kind, all chemists will deny. He begins his doctrine, therefore, not with a fact, but with a petitio principii ; and what is worse, his main experiment is wrong. He was extremely anxious to prove, diat in proportion as air was changed by respiration, it gave out its heat to the blood; he also wished to put respiration and combustion on one level; and by this second thought he forgot entirely what he first had kin mind to prove. Accordingly, having inclosed a Guinea- pig in pure air, and under water, he found that the air which it had respired communicated nearly the same heat to water that burning the same quantity of air would have done : by which he proved much more than he intended ; for he proved plainly by this, that all the heat which respiration can possibly generate is by the fixed air carried from the lungs, and he for- got to reserve any for going into the blood. This slip of Dr. Crawford's leads us to perceive what be- comes of any proportion of heat that may be generated in the lungs. In the first place, this respiration is not a rapid but a slow and gradual oxydation, for the quantity of pure air in the. atmosphere is small. It is not a perfect oxydation, the blood bearing no marks of an acid, nor its oxydation causing any heat. It is not a fair nor permanent oxydation ; for blood soon loses its colour out of the body, and within the body it returns verv quickly from the extremities of the circulating system into the heart, deprived of all its oxygene. The oxy- gene seems but slightly attached to the blood ; it is not so much united with the blood as conveyed by it; and perhaps it is only when this principle is taken from the blood, and assimilated OF THE BLOOD. 75 with the several parts of the body, and fixed among its solids, that it gives out heat. This process of oxydation is intended rather for conveying new properties to the blood than for gene- rating heat, and its chemical changes happen not so much in the lungs as in the extremities of the body. But allowing it to be a perfect combination, a full oxygena- tion of the blood, and that this, like every other oxygenation, must give out heat exactly proportioned to the quantity of spoiled air, it is easy to perceive how this heat may be bestow-. fed; for in respiration there is always a generation of fixed air; there is much water formed and discharged in halitus from the lungs ; the heat, whatever is evolved, must be divided into three proportions : First, when a part of the oxygene attaches itself to the blood, heat will be evolved, which might be sup- posed to enter the blood: But, secondly, there is formed in the same moment a quantity of fixed air, which arises from a second portion of the oxygene uniting with the carbon of the blood; and this fixed air requires some proportion of the heat to keep it in its aerial form. Thirdly, a third portion of tha oxygene unites itself with the hydrogene or inflammable air, and generates water; this water exhales in steam or halitus from the lungs : and how great a proportion of heat necessary to preserve water in the form of steam, is known to every tyro. Now, to prove that all the heat is expended, not upon the blood, but upon the halitus, or upon the fixed air, we have only to retort their own grand experiment upon the believers in this doctrine, viz. that the breath of an animal communicates the same proportion of heat to water that combustion does ; of course none is left to pass into the blood. These philoso- phers do not mean to say that respiration is as rapid as com? bustion, or gives out the same quantity of heat in the same sp?.ces ; there are not even any two combustions, i. e. any two inflammable bodies, which are in this respect alike: they mean, no doubt, to acknowledge the one to be slow and the other rapid ; the)' mean only that the same quantities of air being used in each process, the same quantities of heat will be produced ; that one hundred ounces of air being burnt by a laper, and the same quantity of air exhausted by the breathing :>f any animal, the water which surrounds the air, in either :ase, will be raised to the same temperature, or, if surrounded with ice, the same quantities of ice will be dissolved. But to tell us this, is to tell us nothing ; for without knowing the ra- pidity of the process, we know nothing of the intensity of the heat. Suppose, for example, that one of these philosophers had told us that iron-filings put into water to rust acquire the same quantity of oxygene that iron burnt in the fire does, and, 76 OF THE BLOOD. though slowly, gives out the same quantity of heat, because it can acquire no oxygene but what parts with its heat. All this is true ; but yet burning and rusting are very different, and so combustion and respiration are. While the vapour which issues from the lungs keeps to the temperature of 96°, and while the lungs and heart do not exceed in heat the rest of the body, there can be little chance of any heat being generated in the lungs, except what is balanced and carried off by the hydro- gene and-carbonic airs, or by the halitus from the natural secre- tions of the lungs. i That the animal heat is produced by the action of vessels ; that heat does not proceed from the lungs, but is produced in each part of the body-^*is beautifully proved by what happens in aneurism, where the artery is tied up (in the thigh for exam- ple ;) and where we make, as it were, a great experiment upon ^nimal heat, in the human body itself, 1st. Immediately after the operation, the pulse is stopped, the limb is benumbed, it grows cold, and sinks one or two de- grees below the standard of its natural heat. This is the mo- ment of total interruption in the great trunk, and of particular danger. 2dly, In a little while the limb begins to grow warm ; it swells, and gradually the limb, from being warm only, be- comes hot, and the heat rises many degrees above the standard heat of the limb, and above the general heat of the rest of that system to which it belongs. In this second stage there is still no pulse ; which proves that the circulation in the great artery is not restored; the heat, swelling, and slight inflammation which possesses the w-hole limb, plainly proceed from the uni^ versal action of all the smaller arteries, for the blood has not yet found out any one artery capable of diluting so far as to carry on the circulation easily, and restore the pulse, 3d. But in the next period the pulse begins to creep ; at last it is plainly felt; then it waxes stronger from day to day, till in process of time it beats as vigorously as in the sound limb. Now ihe blood has forced and dilated some greater artery, the blood flows through the limb, as formerly, in one main channel. Tie smaller arteries are freed from their load, and cease fion their excessive action, and, in exact proportion as the pulse re- turns, the unnatural heat subsides gradually, till at last it is re> duced to the common heat of the body. Thus we may per* ceive very clearly, that it is while the communication with the system (and with the lungs of course) by the blood vessels is the most difficult, that the heat rises ; that when the free communi- cation is restored, it falls ; that the intermediate period, in which there is plainly, from the redness and swelling of the limb, an excess of action in all its smaller arteries, is the period OF THE BLOOD. 7^ of excessive heat ; and indeed we may observe, though in a less striking way, the same phenomenon in every inflammation, or, in other terms, in every local disease, viz. the temperature" changed, without any apparent dependence on that of the sys- tem at large. We perceive in the clearest manner that heat is continually formed in all the extremities of the system ; and when we think ofthe processes which are continually going on in various parts, we cannot but believe that oxygene is com- pletely assimilated, and gives out its heat, not when it is receiv- ed into the blood, with which it seems so slightly united, but when it is distributed through the body, and assimilated with its parts, of which it forms so important a principle. In the human body various acids are produced ; the phosphoric acid; the lithic acid, or that which is excreted by the urine ; the aci- dum pingue, or acid of fat, for fat is a proper oxyd from which this animal acid can be easily obtained. In Ants and other animals peculiar acids are formed : these certainly are direct proofs that the oxygene is deposited from the blood. But in reflecting upon this most difficult of all subjects, the generation of heat in the living body, many things are to be ta- ken into the calculation, which seem, on the slightest glance, to be far more important than this deposition of oxygene from the blood. It is a law of nature, to which, as far as we know, no exception is found, that a body while it passes from an aerial to a fluid form, or from a fluid to a solid form, gives out heat. Now, what is the whole business of the living system but a con- tinual assimilation of new parts, making them continually pass from a fluid into a solid form ? The whole nourishment of the body goes on in the extreme vessels, and is a continual assump- tion of new parts. The extreme vessels are continually em- ployed in forming some acids, which appear naked in the se- cretions ; in forming oxyds, as the fat and the jellies ofthe membranous and white parts ; in the various depositions of muscle, bone, tendon, &C. for these are all continually absorbed, thrown off by the urine and incessantly renewed. They are continually employed in filling all the interstices ofthe body with a bland fluid or halitus ; they are continually employed in for- ming secretions of various kinds. In performing all this the power of the vessels may do much; but the ultimate effect in each process must be a chemical change, and perpetual chan- ges will produce a constant heat. Place the organ and focus of this animal heat in the centre of the body, and you are em- barrassed in a thousand difficulties ; allow this heat to arise in each part according to its degree of action, and each part pro- vides for itself. But how then, some will say, shall this heat be reguhted ? I 78 OF THE BLOOD. say plainly by the heart and lungs. The lungs regulate the stimulant power of the blood, the heart regulates the action of the arteries, in so far as regards the stimulus of fulness and distention ; and with these to regulate the centre, nothing can alter the heat of the extremities except partial actions, that is disease. I will conclude then, that oxygene, if it do communicate heat, does so, " not to the lungs nor to the blood, but to the whole body through the medium of the blood." OF THE RESPIRATION OF ANIMALS. The effects of oxydation then are, to redden the blood, to renew its stimulant power, and to communicate heat, not so much to the blood as to the whole body through the medium of the blood, and to assist in the secretions and chemical changes which are incessantly going on in all parts of the system. This is accomplished by the perpetual and rapid motion ofthe blood through the lungs ; and there it is exposed to our atmosphere, which is a mixed fluid very different from what we at first con- ceive, or what our ignorant wishes might desire to have it; not consisting merely of air fit to be breathed, but for the greatest part formed of an air which is most fatal to animal life, whence it has the name of Azotic Gas. Of an hundred measures of atmospheric air, we find twenty-seven only to consist of vital or pure air ; seventy-two consist of azotic air as it is called, fatal to animal life ; and one measure only is fixed air, which is also an unrespirable air. But of these twenty-seven parts of pure air, seventeen parts only are affected by respiration ; so that in respiration we use much less than a fifth part, even ofthe small quantity of air which we take in at each breath, The change of the air by respiration is this chiefly ; that the quantity is diminished by the abstraction of a part of the vital air ; that there is formed a quantity of fixed air, which is gene- rated in the lungs ; and that there is discharged along with these a quantity of watery halitus. Therefore atmospheric air, after it has been breathed, is found to have suffered these changes : First, It contains now a considerable proportion of fixed air, which is easily discovered, and even weighed, because when a caustic alkali is exposed to it, the alkali absorbs the fix- ed air and becomes mild. Secondly, It has less of the vital air,-as is easily ascertained by the eudiometer which measures the purity ofthe whole : and, thirdly, all that remains is mere- ly azotic air, unfit for animal life, or for supporting flame. The oxygene, then, in part unites itself with the blood ; in part it OF THE BLOOD. 79 forms fixed air by combining with the carbon of the lungs, in part it forms water by combining with the hydrogene of'the blood. Respiration frees the blood of two noxious principles, the hydrogene and carbon, the charcoal and the inflammable air : and it insinuates a new principle, viz. the oxygene, into the blood. Nature has appointed but a small proportion of vital air for our use: our atmosphere is so constituted as to hold but a fourth part of vital air, and of that small proportion one half only is used in the lungs. We see by this how necessary this contamination of our atmosphere is, which seems so unfa- vourable to life : nature intended that we should breathe slowly a modified atmosphere ! With nothing but the purest air to breathe, our life would be quickly consumed, like that de- flagration of iron, which is so rapid in vital air, while it burns so moderately and slowly in the common air. These assistances which we have from chemistry are but a promise of what that science may do ; nothing of all that we know concerning the chemistry of the blood is either perfect or sure: we have our expectations still of seeing things more completely explained ; but our expectations are not like those of Mr. Moises, who, in a certain dissertation on the blood, seems so full of his new lessons in chemistry, and so confident of his future achievements in that science, as to expect that muscular "motion shall be veryr thoroughly explained, and that it will be found to be nothing else, in all the world, but" an explosion of hydrogene and oxygene," and God knows what!—but it is after the manner of " a steam-engine ;" and if his scheme holds, they are to be fired off u by means of the nervous electricity of Galvani* !" OF THE RESPIRATION OF PLANTS* But after this view of animal respiration, it is not easy to refrain from saying a few words on the respiration of plants, which bears a relation to animals of infinite importance, and indeed to all nature. Water has all the appearance of a pure and simple element, but it is in truth a compound body, consisting of two parts ; of inflammable air for its basis, and of oxygene combined with it, in that great proportion which the great appetite of in- flammable air requires: and as inflammable air, when saturated * Vide page 2.36. 80 OF THE BLOOD. with oxygene, forms not any acid air, but pure water, it had changed its name, and is now called hydrogene air. When we make water pass through a bed of charcoal, heated to a great degree, the oxygene is seized by the carbon and con- verted into fixed air; while the hydrogene of the water is col- lected in its proper form of inflammable air* When we make water fall drop by drop into a gun-barrel, heated to a high de- gree, we find that the oxygene calcines the gun-barrel, the in- flammable air is collected in the pneumatic apparatus ; and the oxygene which has calcined the iron, and the inflammable air which is received in the glass vessels, exactly account for the quantity- of water which has been analysed. Nay, we can carry this process much farther than many of the other delicate processes in chemistry ; we can re-compose this water. If we mix in a jar inflammable and pure air, and fire the electric spark through them, water is instantly formed, weighing exactly the quantity of both the airs*. Thus, both by synthesis and analysis, we prove that water is composed of pure and of inflammable air ; we find (what it seems difficult to believe, though it was foretold by the great Newton) that water contains an inflammable body; we find, to our great astonishment, while we are regarding the atmosphere which surrounds us as the great magazine of air, that water, where its presence never was suspected, contains an infinitely greater quantity of vital air than the atmosphere ; that our atmosphere contains ■££$ parts only, while water contains TVo- of pure air. We find this decomposition of water offering new connec- tions, and great views of nature, in all the departments of vegetable and animal life; which, in this place at least, we dare not pursue. How perfecdy simple the structure of the most delicate plants and flowers is, may be easily seen in the regularity of those vessels which run through them in one curve or slightly spiral line from root to flower. This simpli- city of structure must be presumed from a thousand facts in gardening, very ordinary but very surprising : parts may be cut from one plant and engrafted on another ; slips shoot and thrive, and grafts may be inserted with either end downwards ; if with the upper part downwards, still it thrives ; the upper part then sends roots into the earth, while that which should nave been the root puts forth leaves. It is still a more curious proof of the simple organization of plants, that all the parts * These beautiful experiments were first made in England by Priestley, War- letire, and Cavendish (vide Philosophical Transactions, anno 1784); and when Lavoisier was first told of water being formed by exploding inflammable air, he said it was a thing which he could not believe. OF THE BLOOD. 81 of plants, their roots, stalks, leaves, fruit, are all capable of performing the common functions apart: the branches or 1 eaves of plants, if plunged in soil, pump up their sap as usual; even the leaves, strewed upon the surface of water, absorb the water ; and if it be impregnated, for example, with fixed air, they absorb the air, decompose it, reserve the carbon, and treasure it up in their own substance, and emit nothing but the purest air. Many things I must here pass over in silence ; as, how plants perform their functions, and assimilate the principles of colour, taste, and smell, only when stimulated and aided by the presence of heat and light; how, when they absorb the atmosphere along with their other food, they use chiefly the carbonic or mephitic airs, and breathe out the pure air again, or reserve only smaller proportions, in order to form their sweets, and modify their various acids ; and fit them for fer- mentation, by which all dieir most valuable products are evolved. Nor dare I stay to relate the curious harmony be- twixt the airs which they thus absorb, and the aerial acids, spirits, and other products, which fermentation displays. I have mentioned the simplicity of their organization, only that I might observe once more how perfecdy they are nou- rished by water alone, and how their simple organization con- verts this apparently simple element into their owrn substance. For water being absorbed by any plant is decomposed thus : the inflammable air is assumed into the plant, and becomes a part of its substance* : the oxygene is in quantity infinitely too great to be altogether digested or used ; the oxygene or vital air therefore exhales from plants, in a continual stream ; all that air which would poison animals is used by plants, and all the air which animals contaminate, plants renew. The freshness of the country, the delights of spring, and all that infusion of health and spirits which we feel in a morning's walk, are now no mystery to u^; for at that hour the plants are by the sun and moisture roused from their sleep, and this process is begun. Perhaps there is not in all nature a more beautiful harmony than this, that the foul breath of animals gives life to plants, while the air respired by plants is useful to animals and delightful to man. • Fishes, many of them live entirely on water ; and water alone sustains thc human body for many weeks under fevers, &c. Vol. II. I* ( 82 ) CHAP. III. OF RESPIRATION, OR THE MANNER IN WHICH THE OXYDATION OF THE BLOOD IS ACCOMPLISHED IN VARIOUS ANIMALS AND IN MAN. i HOSE who are the best acquainted with the comparative anatomy, will best know how natural it is for me to illustrate this function, by comparing various animals with man ; how pleasant, how useful, it is to know these analogies, every stu- dent must feel: and it is now full time to correct many mis- takes into which modern as well as ancient authors have wan- dered, from want of general principles, and from want of ana- tomical knowledge. I shall endeavour to make this chapter interesting and short. At one time all authors believed that the lungs were moved, not by any external agent, but by some internal power residing in the lungs. When in their first essays to investigate this subject they opened the thorax, or rather the body, of amphibious animals, they observed that the creature lay out upon the table with ex- panded lungs ; that the lungs continued for hours to appear like inflated bladders ; the lungs expanded, the heart playing, the creature quite alive. When they emptied their lungs for them by thrusting tubes down the trachea, or pressing the OF RESPIRATION. 83 lungs, the lungs entirely subsided; but in a little while the lungs, at the creature's will, rose again into complete inflation; again they appeared like two tense bladders. Surely, said they, there resides some expansile power in the lungs them- selves ? But when a few of them began to pursue this mistake with serious experiments, they committed absurdities which should be noticed, for they serve to illustrate the true doctrine concerning the expansion of the lungs. Mr. Houston, in our Philosophical Transactions, undertook to prove the following things, which, to use the words of a learned author in our university, " are so improbable as to be incredible ;" first, That the breathing of a Dog is nothing af- fected by any wound of the thorax, if only the lungs themselves be not hurt ; secondly, That the lungs never collapse, though the thorax be laid open ; thirdly, That when the breast is en- tirety laid open, the lungs continue to move, and the thorax also continues to move, but that the motion of the thorax never keeps time with the motions ofthe lungs. But, to do Houston justice, he endeavoured to explain away the inconsistencies of his own experiments; and the world would never have been troubled any more with them, had it not been for a Mr. Bre- mond, a great academician, philosopher, and experiment-ma- ker, who published the following suite of experiments in the academy of Paris. His first mistake is this. " I found (says he) that having stabbed a Dog in one side only, it could run about the house and howL" This is what nobody will doubt. " But also (says he) the air which the Dog took in by the wound when it expir- ed, was pressed out again by the wound when it inspired."— This is one cunning stroke of Mr. Bremond; for had the air entered the chest durmg inspiration, that must have proceeded from the rising of the thorax, which is not the kind of respira- tion which he wanted to prove ; but as the air entered the chest during expiration, it proceeds clearly according to his princi- ples, that the lungs in squeezing out their air have a contractile power ; that they contract by their own motion, and leave the ribs, and so make room for the air. " Next (says Mr. Bremond,) I opened the thorax of a living Dog, and there I saw, that when the lungs contracted the tho- rax dilated, and when the thorax contracted the lungs dilated." But, in fact, it means no more than this, that often in these agonies produced by such cruel experiments upon animals, or by actual wounds in the human body, the diaphragm, chest, every thing which contributes to breathing, is so closely con- tracted, and the pressure is so great, that the lungs are actually compressed and protruded : so that his seeing, as he savs, the 84 OF RESPIRATION. lungs dilated, that is, squeezed out, when the thorax contract- ed, is like the ignorance of a child looking from a carriage- window, who believes and wonders at the trees and houses running backwards. But as no experiment-maker ever allows his experiments to remain incomplete, Mr. Bremond finishes his by the following daring assertion, " that always when he made his incision no more than three inches long, the lungs di- lated themselves with so much violence that they drove out the air before them, protruded themselves through the opening, and macle the blood jerk out at all points."* In short, he re- peats this mistake in every possible form, viz. that the motions ofthe lungs and thorax are direcdy opposite to each other ; that the lungs are contracting while the thorax dilates, and the tho- rax contracting again when the lungs dilate. When I open a Frog, it fills its lungs with perfect ease after both its breast and belly have been entirely cut away. " If admitting air into the thorax could really make the lungs collapse, why do not those of the Frog collapse ?" This is such gross ignorance as should not have been endured in one reading papers before the Royal Academy of France. He is farther back in physiology than Oligerius, Jacobaeus, or Malpighi.—The Frog has a respira- tion peculiar to itself, or at least to its kind. FIRST SPECIES OF RESPIRATION, VIZ. BY A DIAPHRAGM. Under this title I shall explain the respiration of Man, and of animals like Man ; which have heavy lungs, of a s'trong fleshy texture, a prodigious number of blood-vessels passing through them, their lungs lodged entirely in the chest, and their respiration performed by a diaphragm.—I mean to arrange re- spiration according to the mechanism of those organs by which it is performed; and place in the first order that of Man, and animals which in this point resemble Man ; and I say respira- tion by a diaphragm, for this is indeed the only use of a dia- phragm. The support of the great blood vessels, the com- pression of the viscera, the expulsion of the urine and foeces, the ridding the womb of its burden ; all could have been per- formed by the pressure of the abdominal muscles alone! the diaphragm is added merely for breathing. * If one word of this were true, what would become of those who had adhe- sions of the lungs ? Surely if the lungs and thorax moved in opposite directions, the one contracting while the other dilated, the force ot the lungs never could pull down the thorax.—Such patients must die. OF RESPIRATION. 85 Forsaking, for a moment, authority and minute anatomy, let us explain it in the shortest and most intelligible way.__The diaphragm divides the thorax from the abdomen : it is strong, muscular, and acts with great power, enlarging the,thorax ; it is convex towards the breast, and concave towards the belly : when it acts, the belly is protruded, the diaphragm becomes flat, the thorax is enlarged, and a vacuum would be formed, but that instandy the lungs follow it and prevent a vacuum ; for the lungs are free in the thorax, the air has free access to go down into the vesicles of the lungs ; and so when the dia- phragm retires, the lungs follow it, being dilated by the pres- sure of the air which enters by the trachea. But this protrusion of the belly excites the abdominal mus- cles to re-act; their pressure restores the diaphragm to its na- tural form; when pressed back again by the abdominal viscera, it rises in the thorax, becomes again convex towards the lungs, the thorax is reduced in size, the lungs are compressed, and that air is driven out again which they had just received.— The thorax also moves in concert with the diaphragm : and this motion is most curiously arranged ; for, first, the intercos- tal muscles lift the thorax for respiration, in the very moment in which the diaphragm is pressing down, and consequently at the instant when the abdominal muscles, which are attached to the lower borders of the thorax, are relaxed, so that they suffer it to rise. Next, the thorax is to be compressed and pulled down by the abdominal muscles ; and this happens at the very- instant in which the abdominal muscles re-act against the dia- phragm ; so that the abdominal muscles, while they thrust back the diaphragm, pull the lower edges of the thorax down with great power. Thus in Man, and almost all animals, the respiration is per- formed by a diaphragm. SECOND SPECIES OF RESPIRATION, VIZ. THAT OF BIRDS. Birds are supposed to breathe like Man, but have in fact no diaphragm to divide dieir body; they have vesicles, or air bags extending through the whole body, and connected with the true lungs ; their sternum and ribs expand over the whole, and by their motion move the air vesicles, which blow the air through the true lungs ; while the true lungs, far from having any thing to do with a diaphragm, never move. Every one skilled either in anatomy or physiology must know, that one of the greatest physiologists of our times has 86 OF RESPIRATION. written a long paper about the respiration of birds, little under- stood, and in proportion much admired ; of which function he is so thoroughly ignorant, as to explain how they breathe with a diaphragm ; and until I set this point right, my arrangement is good for nothing. " The diaphragm of fowls (says Mr. Hunter,) is thin, trans- parent, and membranous, and runs across the abdomen." But if thin, membranous, and transparent, it can perform none of the functions of a diaphragm, and must be merely such a mem- branous interseptum as some Amphibiae and Reptiles have, supporting the viscera, or confining them in their place. But he thinks to make good his point by acknowledging the imper- fection of this diaphragm ; and adding, that it is moved by cer- tain small muscles, which arise from the inner surface of the ribs, and pull the diaphragm and lungs down. He still persists in calling it a diaphragm in the very sentence in which he in- forms us that " it is perforated in many places with holes of a considerable size." Since Mr. Hunter is so bold as to say of other authors, that theyrhave too limited notions of a diaphragm, we may be allowed to say, that his notions of it are as much too liberal as theirs are too confined. But descriptions and ar- guments of this kind, where the author is entirely wrong, should not be tediously refuted, nor answered in any other way than by a simple statement of the case.* The anatomy of a fowl's respiratory organs is plainly this.— The trachea having descended into the thorax, div ides into two branches ; of which one goes in a simple and ordinary manner into each side of the lungs. The heart, which lies immediately upon this division of the trachea, sends into the lungs two great pulmonic arteries, and receives in return two veins. The lungs themselves are very small, dense, and bloo- dy ; they are somewhat of the shape of the human lungs ; they are seated in the very uppermost part of the chest, are closely braced down to the back, and are indeed in part niched in among the ribs, which in birds have their edges very deep.— * For the respiration of birds, /. e. for raising and depressing the thorax, I see many muscles having a very strong analogy with those of Man. The pectoral muscles are amazingly strong, and their scapulas absolutely fixed, so that these could raise the breast with great power ; but I suspect that no such power is need- ed, that the elasticity merely of the sternum and ribs raises them. There lies un- der these, upon the back, a very strong muscle like our serratus posticus. There lies on the inside ofthe ribs a set of three beautiful muscles like large intercostals; they are quite insulated from all other parts, are seen instantly upon opening the belly : these are what Mr. Hunter calls Muscles of the Diaphragm ; but in truth the breast of a bird is pulled down strongly by its short yet strong abdominal mus- cles, and rises again by its own elasticity with little help ; and these are merely in- tercostal muscles. OF RESPIRATION. 87 These are the true lungs for oxydating the blood; they never move; the air passes through them in the following way. These lungs cannot move, because they are braced down by a membrane very thin, and cobweb-like, yet very strong. This membrane is a peritoneum, lining at once the whole thorax and abdomen (which still are not parted from each other), and it is a covering to the lungs, liver, and other viscera ; but also the same cobweb-like membrane forms cells, which fill the whole cavity from the neck down to the ianus, and from the breast-bone to the back ; and which are so attached to all the surfaces, being, as I have said the lining membrane, that as the breast moves these cells must move. These cells appear at first sight quite irregular; and Mr. Hunter gives but an idle description of them along with that of the septum, which he calls the diaphragm : but I hold it as a principle, that, although we may not see it, yet all is orderly in the animal body ; in fact the order of these cells is extremely regular : first, there is a membrane which comes down from the breast-bone in a perpendicular direction till it touches the viscera ; it runs the whole length of this common cavity of breast and abdomen ; it enters into the great cleft of the liver, and so divides the liver into two lobes, serving as a ligament for the liver, as a mediastinum to divide the great cavity into two, and also as a sort of root or basis for the cells of either side: though beautifully transparent, it is very strong. At the upper end of this mediastinum touches the heart, and there expands into a very large bag exquisitely transparent, which is at once an air-cell and a large pericardium. Next, at its lower end, it touches the gizzard, or stomach, and forms a large cell surrounding it. Behind the liver, which fills all the upper part of this great cavity, and the gizzard which fills all the lower part, lie all the intestines, which are also surrounded with many cells : at the sides the cavity is occupied by- three or four large cells extending from the middle membrane to the flanks of the bird. And, lastly, when we look into those greater cells which are nearest the lungs, we see clearly- many openings, very large, oblique, running flat under that part of the membrane which braces down the lungs, so as to communicate the air from the lungs to all the cells very freely. Now let me add, in one word, that the essential parts of respiration are these : first, there is no diaphragm, no division of breast and belly, the stomach lying upon the rectum- in the pelvis ; a true and muscular diaphragm could not exist in birds, having nothing to do in their scheme of respiration. Second- ly, the true lungs are small, high in the back, quite im- moveable, so that no diaphragm nor no power of vacuum 88 OF RESPIRATION. could unfold them; and these lungs are perforated at every point, so that they could not expand by air. Thirdly, wha t has been confounded with the true lungs is the vast congerie s of abdominal cells, which are of use only in lightening the creature that it may fly, and in forcing the air through the true lungs. Fourthly, there is in the place of a divided abdomen and thorax, with long abdominal muscles, no proper abdomen, a long thorax, a high sternum, and very elastic ribs, extend- ing along the whole body till they almost meet the pelvis, making the abdominal muscles very short ; and the air-cells all along adhere to the inner surface of these bones. With these points clearly before us, we cannot mistake the mode of respiration in birds. The thorax does the w-hole ; the thorax is raised, and immediately the cells are expanded, by w-hich two functions are performed; for the air which comes into the cells, passing through the lungs, oxydates the blood, and the cells become full at the same time so as to make the body lighter. The thorax is depressed again, and the air, which passes now a second time through the hings, may a second time oxydate the blood, for it is not thoroughly spoiled ; and what is spoiled is diluted with the air of many cells, which respiration cannot empty at one stroke. The final cause also is plain. Had the lungs in a fowl been solid and fleshy as they are in man, (or even in any other creature,) and at the same time sufficiently large to perform, without the help of those air bags, all the functions of lungs, they must have been large and heavy in proportion to the body of the fowl ; they must have occupied much room, and added much to the weight. But the lungs of a fow-1 are very dense, very small in proportion to its system, very full of blood, quite fixed, and undilatable ; the rapid course of the air through them backwards and forwards enabling them in their business of oxygenation to do much with little. In short, there are two functions to be performed in birds : first, the oxyda- tion of the blood, which is performed by the small, fleshy, contracted lungs, which lie immoveable in the upper part of the thorax, and through which the air blows continually as through a furnace, while they are quite passive: and secondly, The lightening of their bodies for flying*, which is performed * Although I say the lightening the bird for flying, I do not mean to affirm absolutely, that it is either for flying, that they are made light; for I have given, on the contrary, an example in a bird which seldom flies, viz. the common fowl; and I have added a plan of the Ostrich's cells, which is a swift-footed bird, and never flies: nor do I even affirm, that it is for the sake of lightness that these cells are thus provided. Perhaps one chief use is blowing through the true lungs to ^ v: 46 v rt'<4 jst.°i FIFTH SPECIES OF RESPIRATION, VIZ. THAT OF INSECTS. There is in this kind of respiration no breathing organ like the lungs, but tracheas or air-tubes by which air enters into all parts of their body. What is most perplexing in this species of respiration is the prodigious quantity of air which these creatures receive ; the little connection betwixt the air-tubes and the heart; the im- possibility of tracing blood-vessels from the heart to the vari- ous parts to nourish them ; and the clearness with which we see their air-tubes branching over all parts of their body. The stomach, bowels, and other viscera, the legs and wings, even the very scales of insects, have branches of the air-tubes dividing over their surfaces like the delicate vessels of leaves and flowers. In short, the magnitude of these air-tubes is quite surprising; and their branchings are so minute, delicate, universal over all the body, that it looks almost as if the air- tube had exchanged functions with the heart and arteries. It is plain by these expressions of admiration that I do not mean to attempt so difficult a subject as this at present: I only mention difficulties which it is surprising that others have not declared and investigated, for nothing can be more interesting. The little that we do know shall be simply and plainly told. OF RESPIRATION. 99 The forms of insects are often very strange, their lives very irregular, sometimes in water, sometimes in air; many of them begin in Worms, and end their lives as Flies and Moths; and according to these varieties of their form, or life, or ge- neration, their air-tubes are various. Sometimes, as in the common Bee, they have nearly the form of lungs : they begin like two bags, resembling those of the Alga Marina, or sea-weed, in shape ; and these bags dis- tribute pulmonary tubes, with occasional bag-like dilatations in the course of the tubes, through all the body. More com- monly the air-tubes of insects are direct tubes, mere tracheas, of a very singular construction; they have rings like the tra- cheas of animals; they have a delicate membrane covering these rings and forming them into a tube : the tube continues always rigid like a flexible catheter, or other tube of twisted wire not liable to collapse : they begin by many open mouths opening along the sides of the insect, and they terminate in myriads of vessels, which, in their forms and progress over the various parts of the body, resemble blood-vessels more than it is easy to conceive. These air-tubes being thus rigid, are always full of air, and by their refractions through the transparent parts of the insect's body they give it in the mi- croscope a great degree of brilliancy; as for example in the Louse, whose air-tubes make the brilliant lines and points which are contrasted like a silvery colour with the dark and opaque parts; or in the Mite, which is as beautiful in the mi- croscope as the Louse ; and when the larger insects are pre- pared by drying and varnishing, and preserved in turpentine, the air-tubes are beautiful. Of these curious particulars, the openings of the air-tubes are best seen in the Worm from which the common Butterfly is produced ; we count these holes down the sides one, two, three ; we name them puncta respiratoria, spiracula, or most commonly stigmata: (vide figure 1.) Their transparency and bril- liancy is well understood from the view of the microscopic Louse, figure 2. That particular form in which they resemble more the lungs of animals is seen in the pulmonic bags (a a)—and the tracheas or air-tubes (bb)— of the common Bee, (figure 3.) Their exquisite branchings through the various parte are well 100 OF RESPIRATION. seen in the drawing of the air-tubes which run along the wings of a Bee (figure 4.) or those which twist and ramify Air Tubes' round the intestines and stomach of a Worm; and it is not to be forgotten, that though the beginnings of these tubes in their •great tracheas and near the puncta respiratoria are quite trans- parent, their extreme branches are beautifully white like ves- sels filled with chyle, or rather one might be apt to mistake them for nerves. Of the way in which this function is performed, there must be more varieties than we can know or comprehend: this we may safely conclude from the little that we do know, finding the variety so very great. Almost all insects have their puncta, like those ofthe Cater- pillar, ranged along the side, and inosculating like those of the Louse from branch to branch : often the puncta open along the sides ; but in place of inosculating from branch to branch, all round one side, they inosculate across the belly, the one side communicating with the other. This is best observed in the small Worm from which the Bee proceeds (vide Fig. 6.) which is a magnified drawing of the Bee-worm. And here it must be observed, that, as in other insects, always the stigmata or breathing points correspond neatly with the folds or rings while it continues a Worm, and with the scales or divisions of the body when it becomes a Fly ; in the Bee-worm also the inos- culations answer to the flexures or joints of the body. OF RESPIRATION. 101 Often when the insect lives in water, it has only two puncta respiratoria : these puncta begin either in the snout or in the tail; they are the openings of two great air-tubes which ran down each side of the insect like two aortas, and the insect has means of rising to the surface, takes down a bubble of air along with it, and discharges a bubble of air before it rises again : of this nature are the air tubes of that Worm from which the Ephemeris proceeds. The sketch of the Ephemeris and its air-tubes is given in figure 7.—This Fly has but two spiracu- la; they are so small towards the neck, where their commence- ment is, that their mouths cannot be easily found. The two great air-tubes (ad) are seen like two aortas running all along the body, and their minuter branches (b b) are seen ramifying beautifully upon the abdominal muscles and other parts. Many insects are aquatic when first they are hatched from the egg. They have little gills which serve them while they continue in the water, as, for example, the Ephemeris Fly; but along with these gills they have the ordinary structure of air-tubes, and the day on which they emerge from the water, the gills shrink, and the air-tubes begin their function ; and these chan- ges succeed each other very rapidly in all insects, but most especially in the Ephemeris, which is destined to live but one day. It is most of all singular, that in some insects the number of respiratory points, or puncta, changes according to the various conditions or stages of their existence. For example, a Worm which crawls among the dust, since it must breathe less easily, has more puncta than when it has changed its state to that of a Fly, and has its puncta very freely- exposed to the air: in the Rhinoceros Beede the Worm has more puncta respiratoria, and closer, because it crawls on the ground amidst mud or dust; they are less numerous in the Fly, as its air-holes are always more freely exposed ; and when the Beetle is actually flving, those puncta which were closed by the cases of the wings are fully opened ; so that the insect breathes more free- ly, and perhaps its body is lightened, so that it flies more easi- ly : it is also particular, that in the full grown Beetle, though the puncta be less in number, the lungs are enlarged, they both change their form and become more capacious; for the tubes are mere tracheas or straight lines, with direct branches in the Worm, but in the Beetle they are dilated from point to point into air-bags. Insects in general are bred in eggs, transformed into Worms, assume then the form ofanaurelia, that is, of a Fly, small but full formed, with its legs drawn up, its wings plaited and folded, reaclv at all points to burst from the covering which 102 OF RESPIRATION. surrounds it; for both in posture and in the membranes which surround it, it resembles a foetus. In these three stages it still is nourished by air-tubes : they open by puncta respiratoria while it remains a Worm ; the same puncta still serve it while it is wrapped up an aurelia or concealed Fly ; when the Fly bursts out, the same puncta, the same tubes, which have serv- ed in its former stages, serve it still; only this is most curious, that when from a Worm it proceeds a Fly, the skin which it rids itself of (crawling out of it and pushing with its feet) car- ries off along with it many of the internal parts ; the mouth, the anus, and especially all the respiratory tubes, lose an inter- nal skin, at the same time that the old skin or slough is pushed off from the outward surface of the body ; and when the punc- ta are thus changed, they are left more open than before, and often their number is changed. For the drawing of this slough or skin (a)—from which the Worm has just disengaged itself, and the old air-tubes (b)—inverted, and adhering to the cast skin, see figure 8. which is the figure ofthe Cossus, an affected name by which Mouffet and others have chosen to distinguish the Worm from which the Horned Beetle proceeds. These are the various ways by which insects are supplied with air ; and nothing can be more interesting than to observe the vast proportion of air which they draw in, as if they lived upon that element; the infinite care with which Nature has guarded this main function in insects, ordaining so many vari- OF RESPIRATION. 103 ous ways by which they may in some sense fill their system with air. The variety of ways is changed, and suited, as I have observed, to their various ways of life, and to the vari- ous conditions and stages of their life ; while they are Worms, when they are involved foetuses, and when they have burst their shell and are full grown. In short, Worms, Aureliae, Flies, Beedes, Bees, and all forms of insects, have all of them their tracheas by which they breathe a wonderfully large pro- portion of air. There can be no mistake concerning the function of their air- tubes and of their heart; it is ignorance or inattention only that can cause confusion : the heart of a Caterpillar, of a Snail, ofthe Worms from which various Flies are produced, are seen distinctly through their transparent body, running down their back in form of a tube, sometimes slightly oval, sometimes having frequent dilatations, always throbbing with distinct and equal strokes. Nor can there be any mistake that it is air they breathe; for before we dissect an insect, we must kill it; the contortions of a live Caterpillar prevent all deliberate dissection, or even a view of the parts ; we may poison the insect, as with turpen- tine or spirits ; we commonly drown it: this is done by im- mersing it in a little tepid water. Nay, we find a thing which is at first inconceivable to be really true, that notwithstanding the inosculations ofthe air-tubes with each other, which seems to provide against all such effects, when we close up the stig- mata of an insect one by one,.the parts become in the same pro- portion paraly tic ; if we varnish over the stigmata of one side, that side becomes paralytic ; if we varnish over the stigmata of both sides up to the last holes, the insect lives, but in a very languid condition, it survives in a kind of lethargic state for two days, without any pulsation in its heart; if we also stop the two highest holes, it dies. Of all the examples of respiration, that which is reported by Spallanzani is what I most wonder at, and cannot but doubt. In acescent liquors, or the juices of animal bodies, animalcules are seen plainly with simple glasses, moving sometimes rapid- ly, sometimes slowly ; but never hitherto has any author pre- tended to see their lungs or heart. Mr. Spallanzani say?, " that these animalcules are elliptic bodies j that in the centre of each ellipsis he sees two stars, which are in constant alternate and regular motion, whether the creature rests or moves. Each star-like body has in its centre a small -sr^g y^^^^ss' globe, and every three or four second* 104 OF RESPIRATION. the globules are blown up slowly to three or four times their natural size, and as slowly compressed again ; and every time that the radii are inflated the central globule subsides. On one side of these star-like bodies there is an oval part, which is continually agitated with a trembling motion: he calls the star- like bodies lungs, and the oval body he thinks is the heart."— Spallanzani surely has forgotten that he is speaking of lungs in an aquatic insect: if these star-like bodies have any such use, they must be gills. These are the animalcules which Buffon called organic germs, and from which, as materials and pieces, he built up the animal body. But if all this be true, then the day is come which he little expected, when the organic particles, on the faith of which he built all his system of generation, are proved to be living and moving animalcules, voracious of food, de- vouring each other, breathing air, and having a visible pulsa- ting heart; animalcules deposited from the atmosphere, and generating like other insects of their kind. Thus we are convinced of the importance of respiration, and the absorption of air in all living creatures, from Man even to the meanest reptile : and not least needful in the last and low- est order, which receive in proportion a fuller supply of air than fishes, amphibiae, or Man ; one point chiefly confounds the little knowledge that we have on this subject, viz. that many insects live best in the foulest air. a. The Nostrils.....b. The Tongue. Yft/u f'/ t/tr* \l fft/i/t'ift'/rH Shewing the Flace and-Forrri of l/ieJiu, Shewing theJEffects of lis descending ascending altf-rnntcly Expirnfifi Inspiration xrn CIRCULATION, &C. 105 CHAP. IV. OF THE PECULIARITIES IN THE CIRCULA- TION OF THE FCETUS. JL HE peculiarities of the foetus all relate to the oxydation of the blood, and are such chiefly as fulfil the circulation of the blood without any need of its passing through the lungs, en- abling the foetus to live without that function in its mother's womb. 1. We are assured that the blood which comes to the foetus through the umbilical vein is pure, or of greater value than that which the foetus returns to the mother's system. Either this blood is restored to all its properties merely by passing through the mother's system, and what is thus drained off from the extremities of the mother's system is more than sufficient for the life of the child ; or, without such direct communica- tion, the placenta performs to the foetus a function equivalent to that of the lungs. Then this blood, whose value and proper- ties must be lost, if pushed through the circulation of the liver, passes only in part through the liver, while a chief share of it goes by a side passage, which is called the ductus or cana- lis venosus, under the liver, directly to the heart.* 2. This blood does not pass through the circulation of the lungs ; perhaps it ought not to pass ; for there being no respi- ration, no air admitted to the lungs, the blood might rather be contaminated; perhaps it cannot pass, the lungs never ha- ving been expanded with air : but, however that be, there is a side passage for conveying it from the right to the left side of the heart clear of the lungs. For this use is the foramen ovale, which is an opening of no inconsiderable size betwixt the right and left auricle of the heart; its area is as large as that of the vena cava; and it is sufficient, without the help of the ductus arteriosus, to convey the blood freely from right to left. 3. The ductus arteriosus serves quite another purpose ; for though the circulation ofthe aorta is well maintained in the adult body by the force of one ventricle only, yet in the foetus ®ne ventricle will not suffice. In the foetus the heart must push * N. B. The canalis venosus is marked in thc plan. Vol. II. O 106 CIRCULATION GT its blood not only through that system of vessels which is with* in the body, but also it must push it onwards through a second circle of vessels, viz. those of the placenta; for the iliac arteries do not descend into the thigh and pelvis of the foetus, but the iliac artery itself, with little diminution (very small branches only being given downwards into the pelvis and thigh), turns upwards along the side of the bladder; and these two arteries going out from the navel, form the umbilical cord ; and the heart of the foetus has to give life and action not only to its own internal system, but to these two arteries com- prehending the chief bulk of the aorta, which run out to the distance of three feet along the umbilical cord, and which make wonderful convolutions in the placenta, and terminate with extreme minuteness upon its surface. It is this which occasions the necessity of the ductus arteriosus, which is merely a union or inosculation of the pulmonic artery with the aorta. This union is formed by a great branch of the pul- monic artery in the foetus, joining the aorta below its curve. This great branch (for it is greater than the two branches which go to the lungs) is named the ductus arteriosus, and may be defined an inosculation betwixt the pulmonic artery and the aorta, so very large, that it gives the aorta of the foetus twice its natural size and proportion, and enables the blood of that artery to have the full force of both ventricles ; of the left ventricle through the aorta, and of the right ventricle through the ductus arteriosus by one synchronous stroke. 4. The contaminated blood of the foetus must be returned to the mother, or at least to the placenta ; for which purpose the two iliac arteries are reflected along the side of the bladder as I have just explained. I say the iliac arteries without reserve, because the hypogastric and femoral arteries, that is, the arteries of the pelvis and thigh, though they are the largest branches of all the body in the adult, are in the foetus, ex- tremely small; and thence that smallness of the lower ex- tremities compared with the largeness of the head, whick characterizes die child, and which it takes years to redress. DUCTUS VENOSUS. Thus have I defined these parts and their uses,-in order that their strict anatomy may be the more easily explained ; and the part first mentioned, viz. the ductus venosus, is the part the most difficult to be understood, and never without the help of a plan. In my plan I have endeavoured to elucidate these points. Vol. II t titi', 1, vena CavajUdom THE FOETUS. 107 First, The mere anatomy, connections, and inosculations of the vessels ; showing how the umbilical vein brings in the blood of the mother ; how that vein spreads in the liver and feeds all its left side with blood ; and how the ductus venosus carries part of that blood away from the circulation of the li- ver, conducting it directly onwards to the right side of the heart. Secondly, I have endeavoured to explain what parts of the liver each branch supplies, and how these vessels lie in the liver of a new-born child. Thirdly, I have contrasted with this the change of form in these same vessels, when, as happens in the adult, the form of the liver is changed, and the ductus venosus and the umbilical vein are obliterated, and gone or converted into ligaments of very trivial use or size. The blood from the maternal system transmitted through the placenta, and oxydated, or having undergone some change equivalent to oxydation, comes down along the umbilical Vein :—the vein enters by the navel, adheres to the inner sur- face of the abdomen, enters into the liver at the top of that great transverse cleft which divides the liver into two lobes ; and after entering the liver, it begins, as if it were the regular and peculiar vessel of the liver, to distribute branches through its substance from right to left. , In figure 1.—(ad) shows the umbilical vein—(6) the point at • wjiicb. it enters the liver—(c, 7 master's death ; and notwithstanding all assistance, he was that very evening dead. The pulse is weak, the cough slight, the difficulty of breath- ing more anxious than painful; the face sunk in the features and flushed, or rather of a lurid colour, except when it is cadaverous, pale, and sallow ; the suffocation is sudden ; the lungs have, as Morgagni expresses it, a liver-like, solid con- sistence ; they have no longer the cellular appearance of lungs, for their bronchise are crammed with blood ; their common cellular texture is also full of exuded blood ; they are dense, solid, very heavy, and black, and they sink in water like the lungs of a foetus. The heart is so^urbed in its actions, that it gives but a small, feeble, and trembling pulse : and even in a few days (as in the foetus having an imperfect organization) the heart is wonderfully dilated and enlarged, and filled with fluid and grumous blood. Haller laments the death of friends by this terrible disease, and especially of his own son, " whose body he gave to be opened by those skilled in dissections." Perhaps the heart may be too small for the system to which it belongs ; and this, I doubt not, had been the case with that boy in whom Kerkringius found it so small, that though the boy was nine years old, the heart (i. e. the ventricles) was no bigger than that of a foetus; and the whole heart, auricles, ventricles and all, was no bigger than that of a child born at the full time. But in proportion as the heart was small the vessels were large, not at all aneurismal, but of such a size, and scarcely of such a size, as might suit the heart of a boy of nine years old. This boy had for five years been hectic, that is to say, he had been troubled with no formed disease, but with continual distress, anxiety, weakness, and quick pulse. This heart was plainly inadequate to the functions of any system ; but the case is too slightly sketched for us to find any decided marks of ill oxydated blood. But that the heart may be too big for its system, is a melan- choly fact; for when it becomes relaxed, it enlarges, and as it grows in bulk loses in power. That the heart is enlarged merely by weakness, by submitting to dilatation, by wanting sufficient power to free itself of accumulating blood, is very plain ; for in the plague, in low and pestilential fevers, even in nervous affections, it sometimes enlarges, and from a tempo- rary becomes a mechanical and fixed disease. How often do We read in the preface to such dissections of enlarged heart, u he was of a melancholy temperament, of a slow and se- dentary life, oppressed by misfortunes, and struggling with vexations and grief." In the angina pectoris, which is in its Vol. II. S 138 DISEASES OF first attack no organic disease, we often find the dilated heart pale and tender, so that the fingers may be pushed through its flesh. While the heart gradually enlarges, the system changes, and accommodates itself to its powers. There is little distress ; often we find a heart enlarged to a degree such as we never could have suspected before death. But slowly there is form- ed such an accumulation of ill oxydated blood as oppresses the vital powers, and chokes the motions of the heart, and draws af- ter it those other disorders which are already in part explained. Of the mechanical consciences which follow the enlarged heart, those chiefly attract our attention which prevent the due oxydation ofthe blood. First, The dilatation of the heart draws after it a dilatation of the great veins, so that they become reservoirs as it were ; and the auricle and veins both enlarge so, that the office of the auricular valves is quite lost; the veins feel, or rather the co- lumn of blood in the veins feels the back stroke from the heart, and it is perceived even m the neck by a strong pulsation.— Secondly, These veins, and this monstrous heart, so fill the chest, prevent the blood of the neck descending, and so push aside the lungs, as to compress them to the last degree that is consistent with life.—Thirdly, The enlarged heart accumulates much blood in the system which before did not exist, and that blood dark coloured and unfit for the purposes of life. The proportion betwixt the great mass of ill oxydated blood linge- ring in the veins and about the heart, is increased so very greatly, in opposition to the very small quantity which can now be oxydated in the lungs, that such persons are exposed every moment to the greatest dangers ; and the least accident which draws out more black blood from the veins,, and hurries k to- wards the heart, quite overcomes them. Then there is an ago- nizing and fearful struggle ; the heart often struggles, and often frees itself; but in most cases those who live in this con- dition do, after many escapes, fall down suddenly dead. " A very learned man having this enlargement of the heart while he was still walking about in his ordinary health, his heart would often stop for three or four pulsations, as if struggling with its load, velutque expulsionem moliretur."*—Fourthly, In this enlargement ofthe heart, akhough sometimes there is a perfect and equal pulse, though sometimes also the disease scarcely shows itself till very tar advanced, and after many * Vesalij, lib. i. cap. v, THE HEART. 139 years of slow increase ; yet the heart being continually loaded and often struggling, cannot free itself at one stroke of all its blood ; then, stroke succeeding stroke in a confused irregular way, there is a weak, irregular, intermitting, fluttering pulse. —Fifthly, But Nature, wonderful in her ways, sometimes finds relief from this in the regular constitution of these parts ; for while the heart dilates, and becomes more powerless as it dilates, the aorta (being but poorly filled) contracts in propor- tion as the heart dilates, and accommodates itself to the small quantity of blood which such a heart can give out: and thence the wonder sometimes expressed at finding an aorta extremely slender joined often to an enormous heart. " In opening the body of a shoemaker, says Morgagni, whose heart was wonderfully enlarged, seeming as if you had joined two hearts, what chiefly struck us was the smallness of the aorta, more suitable to a delicate woman than to a man of good stature as this was. The aorta, from its passing under the diaphragm to its great division in the pelvis, was very small. This Morgagni first of all believed was owing to some stricture at the diaphragm ; for the aorta did not pass as usual under the legs of the diaphragm, it passed through a peculiar hole; but he found this tendinous hole quite large and free- Still he believed that all the disorder of the heart arose from the contraction of the aorta, and that again from the crooked posture in which those sit who are of this trade. But that of- ten the artery is contracted in favour of the enlarged ventricle, I am able to prove better than by this case of Morgagni's.— In the first place, the distorted posture of his shoemaker can have no effect; for we must not forget how limber, flexible, and free from disease, the aorta is in those who have the un- happiness to be deformed, and in whom the aorta follows the spine so closely, that often the bones almost meet in their dis- tortions, and hide it. I have cut out these aorta sometimes and laid them on boards, to show the strange angles which they make with such perfect safety. Next I have to observe, that where the auricles and ventricles dilate in old people, the aorta also dilates : for there the aorta is old, partly ossified ; its muscular coat stiff and incapable of action ; it is, in short, as weak as the heart itself, and yields along with it to the accu- mulated blood. But in younger men, the aorta being muscu- lar and strongly contractile, this phenomenon ensues : that as the heart increases in size and weakness every day, it struggles with less effect against the accumulation ; its pulses are im- perfect ; it delivers less blood into the aorta; the aorta, less perfectly filled, is not excited by the same power which for- merly filled it and kept it full : therefore it contracts gradually 140 DISEASES OF and slowly; it preserves still its healthy constitution ; it is limber, pliant, and sound, in its muscular coat. In short, this doctrine of Morgagni's implies only a stationary condition of the aorta ; this other theory implies an active contraction.-— Now Morgagni's shoemaker was a portly man, but his aorta was smaller than a woman's. Even this case of his own im- plies an actual contraction ; since, had this man's aorta con- tinued stationary, it must have been still the aorta of a man of good stature, joined to a large heart. But a perfect proof is this : I have a heart which it would not be easy to describe ; it is not only as big as two hearts joined, but^ I may say, with Bartholine, " ut saepe in Bobus non magis sit aut ponderosior." The heart is bigger actually than an ox's ; it is bigger, I think, by the whole size of its two great auricles; it is injected with wax; it weighs more than four pounds, and is two feet in cir- cumference ; but the aorta is no bigger than the femoral arte- ry at the groin, very straight and even in its diameter, very slender, and with coats which plainlyr have been very thin and suitable to such an artery. Here the artery is equably and fairly contracted to one fourth of its natural size, which sup- poses a natural and sound condition of its coats : and one of two things must have happened, either the artery must have contracted first, opposing the heart and causing it to enlarge ; but then its violent contraction, like the urethra contracting in opposition to the bladder, would have thickened it into a strong muscular tube : or, secondly, the artery must have contracted gently and gradually in favour of the dilatation and weakness of the heart; and then it would remain (as this artery really was) very soft} delicate, and limber ; in short quite natural—I suspect also that where the aorta is enlarged, there is required a strong, small, and muscular heart; because I have an aorta enlarged to a very great degree, the heart being extremely small. These accidents will be noticed chiefly where, in young people, there happens such disproportion of muscular power betwixt the heart and its vessels ; but in the aged, all the parts are but too much disposed to disease, and the whole will enlarge. These, then, are the chief consequences of that enlargement ofthe heart which often so fills the thorax and loads the dia- phragm, that it falls down under the weight of the heart; then the heart is felt lower than natural; and the disorder is nam- ed by most authors the prolapsus cordis. In a young man of twenty years of age, the most miserable creature I ever saw, I have felt a prodigious heart beating as if quite in the abdo- men : at the pit of the stomach the pulsation was particularly strong ; it must have been mistaken for an aneurism of the THE HEART. 141 coeliac artery, had not the heart been felt beating from the na- vel almost to the collar-bone. Whether we are to allow, that the blood sometimes does co- agulate and form polypi in those enlarged hearts, I believe no man in the present state of our knowledge will venture to de- cide. That the blood should coagulate thus firmly, while with- in the body, and that not in a corner of the circulating system but in the heart itself, where always there must be some mo- tion, it is not easy to believe ; nor that such coagulations should remain there, be washed pure by the current of blood, so as to have a leathery colour, and to be firm and strong ; that such coagula should entangle the valves and columnae carneae, shoot up into the great vessels, and hinder the movements, and close, in some degree, the openings of the heart, is quite un- likely : yet if there be such a thing, this must stand as the des- cription of a polypus of the heart. I incline then rather to the opinion of the able and diligent Kerkringius, who calls them pseudo-polypi, bastard polypi, mere clots of blood ; of which he produces drawings from the pulmonic veins, the liver, the heart, the brain, &c. wherever great veins are. That when the heart is monstrously dilated, clots may be formed in it, very large, filling all its cavity, but still happening chiefly in the moment of death, or during its slow approaches, I believe from what Vesalius relates ; who, " in the heart of a nobleman, found two pounds of a dark coloured flesh ; upon which lump, the heart, of monstrous size, was extended like a gravid uterus." But this black flesh, since it was unconnect- ed with the walls of the heart, was a mere clot; which, had it come really from the- womb, Vesalius would have called a false pregnancy, an ovum deforme, or what the vulgar call a mole. This, and all the lesser polypi, those strings of coagulum which entangle the columnae, and stretch upwards into the ves- sels, are really- formed in the moment of death. ' But it is not to be forgotten, that many of the most eminent men have thought quite the reverse of all this. Polypi, when first notic- ed, seemed a strange and awful and frequent cause of death. Having once believed and wondered at such a thing, people did not even like to be disabused ; and when Kerkringius called them pseudo-polypi, the whole physicians, like a hive of bees, swarmed out upon him at once. Tulpius, Malpighi, Pechlinus, ridiculed this opinion. Pechlinus was so offended, that he could not refrain himself from low and mean language. " True polypi there certainly are, says he, but these polypi of Kerkringius are indeed pseudo-polypi, and every blind shaver knows them abundantly well;" (tarn est vulgaris et lippis ton- 142 DISEASES OF soribus notus.) " The shop-boys, says Pechlinus, make such polypi, by pouring vitriolic acid into the veins." Yet with all his bitterness, Pechlinus has not proved, to my satisfaction, either by his arguments, or by his cases, that polypi exist: but he made many believe him, for the ignorance of that time is very singular. Dr. Petrus Russe tells us, that he had once found a polypus in the longitudinal sinus of the dura mater, of a quarter of a yard long : " Let this be put down," says he, " as one proof at least that polypi are sometimes found higher than the nose." What must have been the confusion of their notions, who could thus jumble the ideas of a polypus of the blood-vessels and a polypus of the nose ? They even mistook such clots for living animals. Dr. Ed- ward May sent from England to the celebrated Severinus a description of an Eel which he had found in the cavity of the heart. He entitles it, with some propriety, " His- toria mirabilis anguis bifidi." It is, indeed, a wonderful story-; they describe head and tail, and all fairly, as if it had been bona fide a living creature, and tell us how its head was sticking to the inside of the heart (where you may suppose it was biting,) and how its body was very white and very strong, and its arms or tails, I do not know what to call them, red.—- But what amuses one most of all is the important air of these communications betwixt Severinus and Dr. May; and then Severinus, warning his pupils against incredulity, and telling them, " that though wounds of the heart are really mortal, yet ulcers of the heart certainly are not mortal;" by which he means, that while the Eel was alive it was continually biting the heart.* In short, from these things, we perceive that we need not look into books for any satisfaction on this delicate point; that we must depend upon ourselves, and make a better use of all future occasions ; for unhappily there are no good histories attached to those dissections in which the coagula have been most like to those of a long formed disease, f The heart, which is so often dilated by weakness, is some- times reduced in size by an increase of strength and action.— It becomes dense, firm, thick in substance, but small in its ca- vity ; it appears to be dilated without, but is, in fact, contract- • It is certain enough that small worms are found not only in the , SECOND ORDER. The second set of arteries, which go backwards from the external carotid, comprehend the pharyngeal, the occipital, the auricular. 168 OF THE EXTERNAL CAROTID. 4. PHARYNGEA INFERIOR. The lower pharyngeal* is a small slender artery; which gives no branches deserving to be numbered ; it stands alone, and should be described as one simple artery, whose small branches spread all about the throat in the following manner. This artery is smaller than any other branch of the carotid yet enumerated. It arises opposite to the lingual artery ; and as it arises from the inner side, it comes out in a manner from the fork betwixt the external and internal carotid arteries : it rises upwards very slender and delicate ; it lies deep in the neck, upon the fore-part of the flat vertebrae, or rather lies upon the flat face of the longus colli musclef. After rising in one slender artery, single, without branches or connections, it begins all at once to give twigs. First, It gives branches inwards to the throat; for one twig surrounds the lower part of the pharynx about the root of the tongue, and sometimes goes forwards along with the glosso- pharyngeal nerve into the tongue. Another twig goes to the middle of the pharynx, and wanders towards the velum palati, giving branches to the amyrgdalae. And still another goes higher towards the basis of the skull; it also gives twigs to the velum palati, to the back of the nostrils, to the upper part of the pharynx where the upper constrictor lies (viz. that which comes from the basis of the skull), and it gives small arteries to nourish the basis of the skull; as, to the os sphenoides, to the cuneiform process of the occiput, to the point of the tem- poral bone, and to the cartilage of the Eustachian tube. Secondly, It sends branches outwards to the mastoid muscle, to the jugular vein, to the ganglion of the intercostal nerve, and to the dura mater of the eighth pair ; and one particular branch, very small and delicate, goes along conducted by the great jugular vein, enters together with it into the skull, and makes one of the arteries of the dura mater, but it is a very delicate twig. In general one artery only of the dura mater is known or mentioned; but here we have seen, besides the great artery of the dura mater, lesser arteries entering to it by all the perforations at the basis of the skull. The pharyngeal actually terminates in the dura mater, passing through die foramen lacerum anterius, and sending also a branch in together with * It is named lower pharyngeal, to distinguish it from one which comes down- wards from the internal maxillary. Vide p. 176. f When dissected, it must be taken out in a manner from behind the oesopha- gus. Thc carotids must be raised outwards before it can be seen ; for it lies undec1 them, betwixt them and the throat. OF THE EXTERNAL CAROTID. 169 the jugular vein. The occipital artery also sends one with the jugular vein, one by the foramen mastoideum, and one by a small hole in the occiput. The temporal often sends one through by the hole in the back part of the parietal bone. 5. ARTERIA OCCIPITALIS. The occipital artery is also a simple artery, distributing its twigs about the ear, over the occiput, and down the back of the neck, and having no branches of sufficient importance to be particularly marked. It arises next to the pharyngeal from the back part of the carotid ; and lying particularly deep, it not only is covered at its root by the other branches of the carotid, but is covered in all its course by the thick muscles ofthe neck, except just where it is passing round the mastoid process. At first the occipital artery lies close in among the bones, passing over the transverse process of the atlas, crossing the root of the great jugular vein, and passing under the root of the mastoid process, so as to lie at this place under the belly of the digastric muscle. Still as it encircles the occiput, it passes along very deep under the bellies, first of the trachelo-rr-istoi- deus, and then of the splenius and complexus, and emerges only when it arrives at or near the middle ridge of the occiput; and lastly, it rises with many beautiful branches over the back ofthe head, to meet the branches ofthe temporal artery. In this course the occipital artery sends out the following branches: 1. Branches to the biventer which lies over it, and to the stylo-hyoideus muscle ; and there is one longer artery which attaches itself to the root of the mastoid muscle, and passes along that muscle, to inosculate with the thyroid arteries, or with the lower cervical arteries, which mount upwards as this descends. 2. Next it gives, like the pharyngeal, a small artery, which goes backwards along the jugular vein ; and having entered by the foramen lacerum, attaches itself within the skull to that part of the dura mater which lies under the lobes of the cerebellum. 3. The occipital artery, as it passes under the ear, sends out to it a small posterior artery, which goes to the little lobe ofthe ear, and creeps up along its posterior border. 4. At this point the occipital often gives another artery, Which passes upwards behind the ear, and is named the poste- rior TEMPORAL ARTERY. Vol. II. Y 170 OF THE EXTERNAL CAROTID. 5. The occipital artery, as it passes under the trachelo-mas- toideus and splenius, gives branches to these two muscles ; and it sends out from betwixt the trachelo-mastoideus and complexus a long branch, which descends along the neck a considerable way ; and after having further supplied the sple- nius, complexus, and also the deeper muscles of the neck, it terminates by inosculating with a branch from the axillary ar- tery, which as it crosses the neck is named transversalis colli.— This descending branch of the occipital inosculates also with the vertebral arteries through the interstices of the vertebrae. Having pierced the belly of the complexus, the artery now rises over the occiput in small and beautiful arteries ; the chief of which belong to the occipital belly of the occipito-frontalis muscle and to the skin : it finally ends in inosculations with the back branches of the temporal artery. But of these extreme twigs of the occipital, two are remarkable, because they pass through the skull to the dura mater ; one through a small hole in the occipital spine, and one through that small hole which is behind the mastoid process. Sometimes the hole is in the temporal bone, but more frequently in the suture which sur- rounds the back part of the temporal bone.* 6. ARTERIA POSTERIOR AURIS. The posterior artery of the ear is the smallest and least constant of all the arteries which go off from the carotid ; for it is often wanting, or often comes from some branch, and not from the carotid itself; often from the occipital, sometimes from the pharyngeal artery ; it can scarcely be reckoned as a regular branch of the carotid. This artery also, like the pha- ryngeal and occipital, gives out no distinguished branches which we need to mark ; it chiefly belongs to the ear, it gives branches to the cartilage of the external ear, it sends a larger branch through the stylo-mastoid hole to the internal ear, and the rest of its twigs go to the integuments, or to the bones. The posterior auris arises much higher than any of those arteries which have been just described ; it does not come off from the external carotid till it reaches the parotid gland ; or, rather, it arises where the carotid is plunged into the substance of that gland ; it passes direcdy across under the styloid pro- cess, and over the belly- of the digastric muscle, and then goes up behind the ear ; in this passage it gives branches to the pa- * Viz. the additamentum sutnne squamosa. OF the external carotid. 171 rotid gland, and to the biventer muscle, the parts on which it lies ; next it gives a twig, which furnishes the root of the car- tilage of the ear, and perforates the lowest part ofthe cartilage, so as to spread itself upon the drum of the ear; and this branch, named arteria tympani, is particularly large in the child, which has a peculiar conformation, a preternatural mem- brane covering the drum of the ear. Its next branch, the arteria stylo-mastoidea, is the most remarkable, for it is of considerable size, enters the ma- stoid hole, while the corda-tympani, or great nerve of the face, comes out: it is a chief artery of the internal ear ; for it gives branches, 1. to the tympanum, one of which beautifully sur- rounds the bony circle, and then spreads upon the membrane itself ; 2. to the muscle of the stapes, to the semicircular ca- nals, to the cells of the mastoid process and its delicate ves- sels ; which arteries, when well injected with size, paint the walls of the cavity of the tympanum, and of the semicircular canals. The main artery having given off the arteria tympani and this stylo-mastoid artery, and having passed the stylo-mastoid hole, becomes properly the arteria posterior auris, rising be- hind the ear, and giving its branches to the skin and mastoid muscle, and to the muscle behind the ear (posterior auris,) and to the bone and periosteum, chiefly about the mastoid process ; then its small branches play round the back part of the concha or shell ofthe ear; and, lastly, the artery, still mounting be- hind the ear, ends in small twigs, which go to the fascia of the temporal muscle, and which of course inosculate above the ear with the temporal artery. THIRD ORDER. The third order of arteries includes the termination of the external carotid artery in the temporal and maxillary arteries, which is after the following manner : ^ The artery having entered into the parotid gland, lies there absolutely imbedded in its substance ; and of the two arteries in which it terminates, one passes directly through the sub- stance of the parotid gland, emerges before the ear, mounts upon the temple, and is named of course the temporal arte- ry • it performs here in the temple the same office which the eccipital does behind, viz. it supplies the pericranium, mus- 172 OF the external carotid. cles, and skin : all this is very simple. But the other branch, in which (since it is exceedingly large) one would say the ca- rotid terminates, goes off from the temporal with a sudden bend, sinks very deep under the articulation of the lower jaw, terminates in a lash of branches at the back of the antrum Highmorianum, and there gives branches to the lower jaw, the upper jaw, the inside ofthe cheeks, to the temple (deep ar- teries which lie under the temporal muscle,) to the upper part ofthe pharynx, to the nostrils, and to various other p..rt- : ve cut the great arteries ot the thyroid gland ; the necessity OF THE EXTERNAL CAROTID. 181 of thinking about the tumours of the gland itself, for I have had the unhappiness to see a person perish by suffocation while consulting physicians forbade any operation ; and I had no other than the melancholy privilege of watching, for many hours, the last struggles of a person, who had the day before been walking through all the rooms in tolerable ease and health. Could nothing have been resolved on ? Must we always sub- mit to this ? Might not an incision in the fore part (where few arteries are) have at least uncovered the trachea, given a tem- porary relief, and made the tumour suppurate more freely ? I rtt: extirpation of the tongue, which is mentioned with horror, v ould be a less terrible operation to one acquainted with these teries ; the extirpation of all tumours under the jaws is dan- "vrous; the cutting out completely the parotid gland is a thing rt. ite impossible, since the greatest of all the arteries, viz. the . mporal and the maxillary, lie absolutely imbedded in the g iand. What shall we think, then, of those surgeons who talk in such familiar terms of cutting out the parotid gland ? Bleed- ings from the nose have been so often fatal, that Petit is cele- brated to this day for a discovery which he never made, viz. tin. way of plugging the nose so as to stop this bleeding. Have iA>t the French Society been busy renewing inventions for se- curing even so small an artery as that ofthe dura mater ? In the hair-lip operation, in cutting cancers, in dissecting tumours from all parts ofthe face, the surgeon commands the blood on- ly by knowing these arteries. Cowper the celebrated surgeon and anatomist, had his head so full of this project, that instead of waiting for haemorrhage during his operation, he cut off, two days before, the chief source of the blood. He was going to cut out the parotid gland ; and two days before, he placed a small button of caustic on each side ofthe labial artery where it lies upon the cheek, passed a ligature under it, tied it firm, and then proceeded to his operation next day. But this great anatomist made at one stroke two grievous blunders : he miss- ed, for want of knowledge, the chief arteries of the parotid gland, for they come from the temporal artery ; and, if I mis- take not, he had tied the vein, for most assuredly it is the fascial vein which he is describing in his twelfth table from Bidloo.— How terrible the extirpation of tumours from the gums, throat, tonsils, &c. I need not say ; where the surgeon always uses burning irons instead of needles, where not unfrequendy the patient dies. ( 182 ) SECT. II. OF THE ARTERIES OF THE BRAIN, SPINAL MARROW, AND EYE. e* § 1. OF THE ARTERIES OF THE BRAIN. Ty: he internal carotid arteries are named the ARTE RLE cerebri, as being the chief arteries of the brain ; while-' in truth, the brain is also supplied by two other arteries nearly equal in size, viz. the vertebral arteries, which, though they do indeed arise from a different trunk, viz. the axillary artery, yet are so entirely destined for the brain, give so few branches before they reach the skull, are so important when they arrive there, and above all make so large a communication with the carotid arteries, that without a description of the vertebral ar- teries, any description ofthe carotids must be defective; they unite so with the carotids as to form but one great system of vessels for supplying the brain. The two greatest functions of the animal body, those of the womb and of the brain, the one for the life of the individual, the other for the continuation of the species, are the most libe- rally supplied with blood. The womb has on each side two arteries ; it has two spermatics, and two hypogastrics, and the inosculations of these vessels are very large and free. The brain has two great arteries on each side ; it has two carotids, and two vertebral arteries ; they are infinitely larger than those of the womb ; their inosculations are so particular, that there are no others like them in all the body7: the injection of any- one artery easily fills the whole ; the preservation of but one artery saves the life of the creature, when the others are stopped. These four arteries alone convey to the head the fifth part of the whole mass of blood. This is the calculation of the older authors ; and even those who would settle it at the lowest point still acknowledge, that the carotid and vertebral arteries re- ceive at least the tenth part of all the blood ofthe body. The brain then, which weighs not a fortieth part of the whole body. ARTERIES OF THE BRAIN. 183 receives one tenth of all the blood ; a proportion which must occasion surprise. Besides the profusion of blood which thus rushes into the brain, the impetus with which it forces its way seems dange- rous ; and Nature also seems to have provided against the danger. We cannot be but sensible of this danger; for the slightest increase of velocity occasions strange feelings, if not absolute pain. We cannot run for any length of way, nor as- cend a stair rapidly, nor suffer a paroxysm of fever, nor in short have the circulation quickened by violent exertions, by emotions of the mind, or by disease, without feeling an alar- ming beating within the head ; we feel it particularly in the carotid canal where the artery passes through the bone. If it continue from disease, or if we persist in our exertions, gid- diness, blindness, ringing of the ears, come on. Haller re- members, that while he was lying in a bad fever, he suffered so much from the pulsations of the carotid artery within the skull, that his head was lifted from his pillow at every- stroke. I wish he had said, " seemed to be lifted from his pillow at every stroke ;" for it was rather a sickly feeling than what could actually happen. Did this vast column of blood rush directly into the brain, we do not'know what might be its effects; but surely they could not be harmless, since Nature has provided against it in Man, and in the lower animals which hang their heads, with a pecu- liar care. In Man, this blood is retarded chiefly by the tortu- ous course which the artery is obliged to follow, and by that long bony canal which, by holding the carotid as in a sheath, must suppress its violent action, and at least prevent its being dilated by force of the blood, when, as often happens, the low- er part of the artery is more full and tense. Perhaps also it may have some effect, that the carotid, as it lies by the side of the sella turcica, is not naked and free, but is inclosed in a venous sinus, which consists of cells like those of the male pe- nis, and in the heart of which the carotid lies bathed in the blood. It is also peculiar in all the arteries of the brain, that they do not enter in trunks into its substance. This seems to be a vio- lence which the soft texture of the brain could not bear ; but all the arteries having perforated the dura mater, attach them- selves to the pia mater, a delicate membrane, which is the im- mediate covering ofthe brain ; which follows all its divisions, lobes, and convolutions ; which enters all its cavities, and lines its internal surfaces as it covers the external. To this mem- brane of the brain the arteries attach themselves : it conducts them everv where along the surface of the brain, and into its 184 OF THE ARTERIES cavities ; and when the arteries are to enter into the substance of the brain, they have already branched so minutely upon the pia mater, that they enter into the pulpy substance in the most delicate twigs ; so that having injected the brain, at whatever level you cut into it, you find its white surface dotted with red points regularly, and like the dots of a pin. But in the lower animals, especially in the Calf, the Deer, the Sheep, which hang their heads in feeding, there is a pro- vision of so singular a nature, that we can have no doubt that these contortions of the great trunks and minute divisionr ~r the smaller arteries in Man have the same final cause ; ";;r in those creatures the carotid, before it enters the brain, *irsr divides into innumerable smaller arteries. Not one of these is sent off for any particular function : they are immi'ia fly reunited again, and gathered together into one trunk ; and then the force of the blood being thus broken, the artery divides a second time into branches of the ordinary form, which enter safely into the substance of the brain. It is still further supposed, that the arteries of the brain have this peculiarity, distinct from all others in the body, that as they enter the skull they lay aside one of their coats, and that of course the arteries of the brain are peculiarly weak. That the arteries of the brain want that outward coat of cellu- lar substance which all arteries passing through other cavities or along the limbs have, is no doubt true, and so far they are thinner: but how much they are weakened by this loss, it is not easy to say ; for they want none of the coats which are es- sential to the constitution of an artery7; and this cellular coat, though it constitutes much of the thickness of an artery, has, I believe, but little to do with its strength. Yet true it is, that the arteries of the brain, either from being weaker in them- selves, being less supported, lying upon the soft and pulpy substance of the brain, are more frequently burst by falls, or even by the slightest accidents, than the arteries of any other part, even the limbs, however much exposed. Our injections burst them very often ; the slightest blow or fall upon the head often produces an internal effusion of blood, which occasions death; but that the arteries of the> brain are so delicate as to be burst by a false step, so as to produce a fatal aneurism within the brain, is a truth perhaps not commonly known. A young woman, canying in her arms her first child, about six months old, slipped her foot with a slight shock ; but it was on plain and even ground, and she did not fall down. In the instant of this shock she was sensible of a sudden pain in the right side of her head: it was so peculiar, that she said she could cover the point with her finger ; and though slighter OF THE BRAIN. 185 at intervals, this pain never left her to the moment of her death. She walked home, went about her little family-mat- ters, suckled her child ; but was seized that evening with sickness, not violent like that of any sudden disease, but rather like the easy vomiting of a pregnant woman. She continued very sick, with slight headach ; but still was out of bed all day long, went about her household affairs, and had no symptom which could lead one to suspect her very dan- gerous condition, or what a dreadful accident had happened. She got up during the night after this accident for some cool drink, felt herself extremely giddy, was obliged to support herself by a chest of drawers which stood by her bedside, and went to bed again immediately. On the evening of the sec. nd day she got out of bed, made tea as usual, was out of bed during the evening, had no complaint, except the continual sickness, slight pain of the head, and giddiness still slighter. That night she expired. Her pulse all along had beat low and weak, and never more than 60 in the minute. When I was brought to open the body, I heard nothing of the pain of her head, though it was fixed and constant, and without that nothing could be more puzzling than this combi- nation of circumstances. First, the sudden slipping of her foot, and the incessant sickness which ensued, suggested the idea of hernia ; but no such secret was known among her rela- tions ; and upon opening the abdomen, no hernia was found, neither open nor concealed, as in the thyroid hole. Next we were informed of a palpitation, which had been usual with her. It appeared that she had complained chiefly about the period of her first menstruation, and some years before her marriage. It seemed to be hysterical merely ; but upon opening the thorax, we found the heart wonderfully en- larged and crammed with a dark and grumous blood. But next a new scene opened upon us ; and this enlargement of the heart appeared to arise like that of the liver, which so often accompanies fractured skull, from the languid action of the heart and torpor of all the system in those who lie even for a few days comatose. Now, for the first time, I was informed that the shock of slipping her foot had caused a sudden pain of the head ; that it was pointed, confined to one single spot, incessant, accom- panied with perpetual vomiting or desire to vomit, and with giddiness during the night. Upon opening the head, I found the dura mater of a most singular appearance ; livid, or rather like the gizzard of a fowl, with green and changing colours. Having cut it open, the pia mater appeared like red currant jelly, with fresh coa- VOL. II. 8 A 186 OF THE ARTERIES gulated blood so firmly attached to it, that it seemed as if driven into its very substance and incorporated with it. Upon cutting and tearing open the pia mater, each convolution of the brain was surrounded and separated from that next it by coagulated blood. Upon cutting into the ventricles of the brain, that of the right side was found to contain four ounces of entire and coagulated blood ; the cavity at first view was like opening a ventricle of the heart; the blood, very dark and firmly coagulated, was forced out by the pressure of the sur- rounding parts ; the coagulum became gradually firmer and whiter, till it turned to a very firm stringy clot, which s*u\ck in the mouth of the middle artery of the brain. Beir( .',a; fully examined, it was found to be sticking firm in the mom! of the artery which had burst, as if by the separation of t> of its rings. The blood, which thus filled the right ventric^., had also made its way down in prodigious quantity into the third and fourth ventricles, quite into the occipital hole ; but the opposite ventricle of the same side it had not filled. The quantity of blood ascending to the head is exceedingly great; its free circulation in all the arteries is perfecdy secured; and the plan of its distribution is extremely simple, for the carotid entering by the os petrosum gives three branches. First, A branch which unites the two carotids with the two vertebrals, and forms the fore part of the circle of Willis. Secondly, It gives an artery to the great middle lobe, whence it is named the great middle artery of the brain. Thirdly, An artery which is named anterior cerebri, as belonging to the fore part of the brain. But the vertebral, as it arises through the occipital hole, lies upon the cerebellum, and supplies all the cerebellum, and also the back part of the brain. One branch goes to the back part of the cerebellum, another to the fore part of the cerebellum, a third branch goes to the back part of the brain j and thus there is formed betwixt the carotid and the vertebral, by means of the great inosculation of the circle of Willis, one great set of vessels; which should first of all be described free from all the interruptions of trivial arteries, which go off from point to point, but of which the destinations cannot be important, which are hardly known, which do not go in any two subjects the same way. OF THE BRAIN. 187 OF THE INTERNAL CAROTID ARTERY. The internal carotid artery leaves the external carotid at the angle of the jaw: it is so inclined to contortions, that at this point it even bulges, and seems the outermost of the two. In mounting along the neck, it is tied by cellular substance to the fore part of the rectus or straight musele of the neck, and it is also connected with the par vagum and intercostal nerve ; the ganglion of the intercostal, or sympathetic nerve, lies by its s'de; the nerve, before it forms this ganglion, comes down s.nr'' .nd thread-like through the same canal by which the carotid passes into the skull. The contortions of the carotid are great, both before and after its passage through the bony canal ; but within the canal it is forced to particular and successive bendings, such as in- dicate plainly some design of Nature; for the canal for the artery is long and tortuous, while the nerves and veins pass through plain and simple holes. When the carotid first pre- sents itself to enter the skull, it is curved, and is a little be- hind its hole; it bends forwards and inwards a little, and so enters the canal; in entering the canal it rises almost perpendi- cularly upwards, but soon bends forwards again, lying, as it were, upon the floor of the canal; then it bends again upwards and forwards, to emerge from the canal; by which turn the portion of the artery which is engaged in the canal has the form of an Italic^ Even after it gets into the skull, it must still bend once more sidewise and forwards, as if to meet its fellow, and to get to the side of the sella turcica ; then it goes directly forwards till it touches the anterior clynoid process ; and then doubling back, or returning upon itself, it rises per- pendicularly ; and so perpendicular is this last turn, that when cut across, the mouth of the artery gapes perpendicularly up- wards : here it begins to give its branches to the brain. It is by the side of the sella turcica that the cavernous si- nus surrounds the artery. This sinus is formed by the two plates or lamellae ofthe dura mater, parting from each other, and leaving an interstice full of cells, like those of the penis or of the placenta. It is filled with blood, by communication with several of the smaller sinuses or veins about the basis of the brain: the ophthalmic veins bring into it the blood from the eye ; four or five small veins descending from the ioss.i S\ i- i bring blood into it from the middle parts of the brain ; the sinuses of the os petrosum (both on its upper ani lower grooves) open into it, one high, another lower down, and that circular sinus or vein which surrounds the root of the optic 188 OF THE ARTERIES nerves opens into it from either side. All this blood is poured into the cells, bathes the carotid artery which lies naked in it; and by the side of the carotid artery lies also that small nerve of the sixth pair which begins the great intercostal nerve, naked in the blood ; it is tinged by the blood, and its branches retain the tinge some way down the neck. Vieussens first discovered this curious structure ; Ridley denied it, and Haller at last in his turn confirmed it. Vieus- sens believed that the sinus which deposited this blood con- veyed it av> ay again. Haller says that this is the pecu' office of that vein which accompanies the carotid artery, :hu. which is named the vena sodalis arterias carotidis. It was once supposed that certain small arteries opened also into the sinus; but it has neither arteries, nor pulsation. Thus we trace the carotid through its canal, through the cavernous sinus, up to the side of the sella turcica, and about to enter the brain, to give off the arteries of the brain. But before we describe these, it will be easy to count shortly those little twigs which it gives off in the canal and in the sinus. The carotid artery seldom gives out arteries before it enters the skull; it is a lusus nature, when it does happen that the occipital or pharyngeal arteries come off from it. The first twig, which in any case it gives off, is sometimes a small artery, which returns downwards along with the upper maxillary nerve*; next a small twig, accompanied by a branch from the meningeal artery, goes into the tympanum by way of the aquae ductus Fallopii; and next, while the artery is within the sinus cavernosus, it gives out two little branches, the one forwards the other backwards, named arteries of the re- ceptaculum. 1. The little artery which goes backwards from the sinus or receptaculum goes chiefly to that part of the dura mater which covers the posterior clynoid process, and which covers the cuneiform process of the occipital bone ; it gives twigs to the 4th, 5th, and 6th pair of nerves and to the pituitary gland ; in short, to all the parts at the back of the sella turcica; it ends in inosculations with those twigs of the vertebral artery, which come off from the vertebral before it enters the skull. 2. The little artery which comes out from the receptaculum to go forwards, arises where the carotid is crossed by the 6th pair, mistaken for a nerve by those who suppose that the inter- costal arises from a branch of the 5th pair. The distribution of this little artery is nearly the same with that of the first, * The second branch of the 5th pair. OF THE BRAIN. 189 for it belongs to the 3d, 4th, and 5th pair of nerves, and to the pituitary gland. The carotid having^ risen to the anterior clynoid process, gives out there a small artery, no bigger than a crow-quill, which enters direcdy into the orbitary hole, accompanies the optic nerve into the eye, furnishes the eye, the eyelids, the muscles, and the lachrymal gland, and sends out branches up- on the forehead, viz. the frontal arteries in which it ends.— This is a short history of the ophthalmic artery ; which as it furnishes all the arteries of the eye, must be described apart. ,® DIVISION OF THE INTERNAL CAROTID. The carotid, now about to enter into the brain, divides at the sella turcica into three arteries ; one to the fore lobe, ano- ther to the middle lobe, and a third to form the circle of Wil- lis. These arteries are usually so numbered that the commu- nicating branch is first described, next the anterior artery of the brain, and lastly the middle artery of the brain. But of this arrangement no one who is accustomed to observe the course of this artery can entirely approve ; for when the caro- tid rises from the side of the sella turcica, it divides into its three branches all at once, in a tripod-like form : the middle branch ofthe tripod is largest; the next, which goes forwards to the fore lobe of the brain, is smaller ; the third, which is the communicating branch, goes backwards to unite with the ver- tebral artery and form the circle of Willis, is the smallest of all. The middle artery of the brain then is, from its great size, to be regarded as the trunk. 1. ARTERIA MEDIA CEREBRI. The middle lobe ofthe brain is separated from the anterior lobe by a very deep sulcus or furrow, which is named fissura sylvii. This fissura Sylvii is formed by the transverse pro- cess ofthe sphenoid bone, or, in other words, by that very sharp line which runs out laterally from each ofthe clinoid process- es, and which parts the fore lobe, which lies in the shallow part of the skull upon the orbitary processes of the frontal bone, from the middle lobe, which is the largest of all, and lies in the 190 OF THE ARTERIES deepest part of the skull behind the clynoid processes. Thc middle artery of the brain having risen from the side of the sella turcica, runs straight along this fossa Sylvii, and is real- ly the continued trunk ofthe carotid ; it is larger than the artery at the wrist; it goes directly outwards, viz. towards the tem- ple : it runs along the fossa Sylvii, and is lodged deep in that cleft; where it lies deep, it divides into two great branches, one deep and one superficial ; it gives some branches to the anterior lobe, but it is chiefly limited to the middle lobe of the brain; its branches to the posterior lobe, or inosculations "rifh any- branches ofthe basilar artery, are comparatively few. Thus the artery ends by passing into the substance of the brain. But nearer the sella turcica and before it enters into the fossa Sylvii, it gives some small and delicate arteries ; the consideration of which seems to be unimportant at first view, but which is really useful in explaining the anatomy of the brain. It gives small twigs to the pituitary gland, to the optic nerve, to the tentorium, and especially to the pia mater covering the basis of the brain. Among these small twigs certain sets of arteries make a very distinguished figure. 1. There is one small artery which runs up into the anterior horn of the lateral ventricle, and forms that great plexus which lies along the floor of the ventricle, named plexus choroides. This, then, is die artery of the choroid plexus. 2. There is a set of arteries, of considerable number, but vaiying in respect of number, small as sewing threads, which inosculate repeatedly with each other, and which are scattered widely and beautifully over the crura cerebri and basis of the brain, forming in the pia mater a plexus or web of vessels.— This part ofthe pia mater is named velum from its beauty and delicacy ; and this is what Wepfor, among other older authors, considered as a species at least of the rete mirabile : but that name implies a peculiar office, as in beasts, which this delicate net-work of vessels cannot have. 2. ARTERIA ANTERIOR CEREBRI. The fore artery ofthe brain comes off from the middle artery at right angles nearly; for the great or middle artery ; uns directly outwards towards the temple, while this second artery runs directly forwards along the fore lobe ofthe brain.— It is named sometimes the artery of the corpus callosum, be- cause that of two great branches into which it is divided one goes to that part of the brain. The corpus callosum (a most absurd name for any part ofthe brain) is the white and medul- OF THE BRAIN. 191 lary substance where the two hemispheres of the brain are joined ; and upon separating the two hemispheres with the fingers, the corpus callosum is seen like a large white arch, and the artery of the corpus callosum is seen also arching over its surface. The anatomy of the arteria anterior cerebri may therefore be explained thus : first, it goes off at right angles from the middle artery of the brain, which is to be considered as the trunk, and there it often gives small twigs to the olfactory and optic nerves : next the two anterior arteries of each side, while they go forwards as if towards the crista galli, bend a litde to- wards each other ; they almost meet, but do not absolutely touch ; they form a communication with each other, which of course is exceedingly short, but pretty large. It is this short communication which completes the circle of Willis at its fore part. This cross communication betwixt the arteries of the opposite sides passes just before the sella turcica and pituitary gland, and exacdy in the middle it sends off an artery, which goes down into the third ventricle, and gives branches to the fore part of the fornix and to the septum lucidum. After this communication, both arteries rise, with a large sweep along the flat surface of that deep division which the falx makes betwixt the two hemispheres of the brain ; there each divides into its two great branches ; one attaches itself to the corpus callosum, or that arch which we see upon holding apart the two hemispheres ; it arches along with the corpus callosum so as to describe a semicircle ; it is the larger of the two branches ; it is named arteria corporis callosi : the other branch keeps upon the flat surface of the brain, where the one hemisphere lies flat upon the other, and it rises in a beautiful arch within the pia mater, dividing into beautiful and very minute ramifications before it enters actually into the sub- stance of the brain. These two great branches ofthe anterior artery are well dis- tinguished by Wepfer by the names of arteria profunda and arteria sublimis (the deep and superficial of the anterior arte- ry ) as there is a deep and a superficial branch of the middle artery The arch of the arteria anterior cerebri overhangs in a manner that ofthe artery of the corpus callosum, and both of them inosculate under the falx with the arteries of the oppo- site side. 3. ARTERIA COMMUNICANS. The communicating artery goes as directly backwards from the middle artery as the anterior artery goes forwards^- 192 OF THE VERTEBRAL ARTERY. It is small, proceeds backwards, and a little inwards ; it goes round the sides ofthe corpora mamillaria, and is about a quar- ter of an inch in length before it meets the vertebral artery ; and though it does give off small twigs, as to the infundibulum, to the optic nerve, to the crura cerebri, and especially one of greater size, to the choroid plexus ; yet all these are trivial arteries, such as every trunk at the basis of the brain gives off. It is not its twigs that are to be observed, but itself only that is important, as forming one of the largest and important ino- culations of the body. It unites the middle artery of w? brain, which is the trunk of the carotid, with the posterior ar tery of the brain, which is the first and greatest branch of th< vertebral artery. This anastomosis is the circle of Willis, too remarkable i.ot to have been very long observed; it was drawn by Veslingiusj and by Casserius ; it is but ill represented by Bidloo and by Cowper: it is not a circle, but is right lined, and of course an- gular : it is of very unequal size ; in one body it is large, in another smaller, often even in the same body ; it is irregular, the one side being large and the other small. This inosculation brings us round to the first ofthe vertebral arteries, viz. the arteria posterior cerebri ; forthever^ tebral artery gives two arteries to the cerebellum, and one to the back part of the brain. ® OF THE VERTEBRAL ARTERY. The vertebral artery, though but the secondary artery ofthe head, is a principal one of the brain, and conveys a very great proportion of blood ; and its turnings and windings before it enters the skull are almost as particular as those of the carotid itself. The vertebral is among the first branches of the axil- lary artery, and comes off from it where it lies across the root of the neck. The two lower ganglions of the sympathetic nerves lie over it, and their threads surround iis trunk, making curious net-works round it. The artery then enters into the canal prepared for it in the transverse processes of the verte- bra, commonly getting in by the 6th vertebra : but in this it is irregular, sometimes entering into the 7th or lowest; and it has been seen entering into the uppermost hole but one. In this canal it ascends in a direct line from the bottom of the neck t© the top ; but like the carotid it makes great contortions OF THE VERTEBRAL ARTERY. 193 before it enters the skull : for when it has reached the second vertebra, its transverse process being rather longer than those ofthe lower vertebras, the artery is forced to incline outwards • and the transverse process of the adas or first vertebra being still much longer, the artery in passing through it is carried still farther outwards ; it is forced to make a very sudden turn, and is quite exposed. When the artery has passed through the transverse process of the atlas, it makes another very sudden turn, lies flat upon the circle of that vertebra, so as to make a large hollowness or groove upon the bone, and then it enters the foramen magnum by rising in a perpendicu- lar direction ; and then again it bends and inclines forwards, laying flat along the cuneiform process of the occipital bone, where it soon meets its fellow, and the two uniting form the basilar artery. This basilar artery lies, with regard to the bone, upon the cuneiform process of the os occipitis, and runs along it from the foramen magnum to the sella turcica ; with regard to the brain, it lies upon that great tubercle which is named the tu- ber annulare or pons Varolii; as it lies upon the tuber annu- lare, it marks it with a large furrow ; and as it goes along in one great trunk, it gives out from each side little arteries, which belong to this tuber annulare. These also make smaller fur- rows on its surface. The vertebral artery has, like the carotid, its three great branches. 1. ARTERIA CEREBELLI POSTERIOR. The posterior artery, or lower artery of the ce- rebellum, is small and not regular. It comes off from the basilar artery either immediately after the union ofthe verte- brals, or from the vertebral artery immediately before the un- ion. It is often smaller on one side than on the other, and sometimes it is wanting on one side. It moves downwards in a sort of retrograde course betwixt the accessory nerve of Willis and the group of fibres which form the eighth pair, and dives in betwixt the cerebellum and the medulla oblongata.— Its larger branches spread out upon the pia mater, and then enter into the medullary substance. They belong to the ce- * Vol. II. 2 B 194 OF the vertebral artery. rebellum, to the spinal marrow, and some of them to the pons Varolii. But there are also smaller and particular twigs, as twigs to the eighth and ninth pairs of nerves : one also which enters into the fourth ventricle, to form a sort of velum or choroid plexus there : and as this posterior artery winds down- wards under the cerebellum, it gives many branches about the vermis, and small twigs which run betwixt the lower point of the pons Varolii and the pyramidal bodies. Next the arteria basilaris proceeds forwards along the pons Varolii in one great trunk : now the pons Varolii is just the tuberosity produced by the crura cerebri and ctreb Hi, meeting and uniting to form the spinal marrow. The corpora olivaria and pyramidalia are just two bulgings at the root of the spinal marrow ; and as every great artery, whatever i: ^ destination may be, gives twigs to those parts which it pa-ses over, so does the basilar artery-; giving twigs first to the cor- pora olivaria and pyramidalia, next to the crura cerebelli and to the crura cerebri ; and as it runs along the pons Varolii it distributes little arteries to it from right to left. These little arteries also mark the sides of the pons with small furrows, which are seen when the arteries are dissected away7. One of these transverse arteries, longer than the rest, looks like ano- ther posterior cerebri. It goes to the seventh pair, or audito- ry nerve, in the following way : the seventh pair of nerves proceeds from the back part of the pons Varolii; and as it goes forwards, the two nerves which it consists of, viz. the portio dura and the portio mollis, are separated from each other by a small and very beautiful artery which shoots in be- twixt them, and enters along with them into the ear. The basilar artery also gives twigs to the fifth and sixth pairs of nerves which arise from the fore part of the pons, as the se- venth pair arises from behind. Arrived at the fore part of the pons Varolii, the vertebral artery gives off almost at one point four great arteries, two to the right hand and two to the left. These are the anterior ce- rebelli and the posterior cerebri. 2. ANTERIOR CEREBELLI. The anterior artery of the cerebellum, or the up- per artery as it is called, goes off at right angles from the ba- silar artefy, and bends round the crura cerebri to get to the cerebellum. It gives its branches first to the crura cerebelli, to the cerebellum, and to the vermis. Secondly, There is a greater artery going over all the upper part of the cerebellum. OF THE VERTEBRAL ARTERY. 195 (where it lies under the brain,) and also another which keeps closer to the brain than to the cerebellum, branches over that velum or delicate part of the pia mater which is interposed be- twixt the cerebellum and brain ; and going along it supplies the crura cerebri, and arrives at last at the place ofthe nates, testes, and pineal gland, and attaches itself to them. Some of the twigs go down into the fourth ventricle. 3. ARTERIA POSTERIOR CEREBRI. The posterior artery of the brain goes off immediate- ly after this, is like it, runs parallel with it, is larger, goes to the posterior lobe of the brain, and receives near its root the communicating artery from the carotid, which, forms the cir- cle of Willis. Where this posterior cerebri and the anterior eerebelli run parallel with each other, the third pair of nerves rises betwixt them. The posterior cerebri first gives a small twig on either side to the bottom of the third ventricle which runs so far forwards as to give branches to the thalami, cen- trum geminum, infundibulum, and to the crura fornicis. Then the main artery bending like that last described round the cru- ra cerebri, and passing deep into the great division betwixt the cerebellum and brain, arches upwards towards the back lobes of the brain ; but before it arrives there, it gives first small twigs to the crura cerebri, and then another notable artery (though small) destined for the internal surfaces of the ventri- cles. This is a chief artery of the choroid plexus ; it enters the lateral ventricle by the posterior horn ; goes along with the cornu ammonis : helps to form the choroid plexus ; inosculates, of course, with the choroid arteries from the carotid; and twigs also go from this artery to the nates, testes, and pineal gland, or in other words, to the velum which separates the cerebell- um from the brain, which closes the ventricle behind, and which covers the pineal gland, and is a membrane or velum to it also; the pineal gland, nates, and testes, being situated neither in any of the ventricles, nor on the surface of the brain, but betwixt the surface of the brain and cerebellum, where the one lies upon the other. After this second branch to the internal surfaces, the great trunk of the posterior cerebri branches profusely like a tree all over the back part ofthe brain, inosculating forwards with the middle artery of the brain, and also with the artery of the cor- pus callosum. 196 OF THE ARTERIES Thus is the whole brain supplied with blood ; and next in order come the arteries ofthe spinal marrow. § 2. OF THE ARTERIES OF THE SPINAL MARROW. I have mentioned none of those smaller arteries which the vertebral gives off before entering the skull, because being destined chiefly for the spinal marrow, they belong to this se- cond class. The vertebral artery, as it mounts along its canal towards the head, gives at each step, or as it passes each vertebra, a delicate twig ; these little arteries pass through the interverte- bral spaces, go to the deeper muscles ofthe neck, and inoscu- late with the thyroid and cervical arteries. In like manner, other small arteries go inwards to the spinal marrow at the place where each nerve comes out. They enter into the sheath of the spinal marrow, and inosctdate with the chief arteries of the medulla spinalis. As the vertebral passes through the atlas, both above and below that bone, it gives out much larger arteries to the mus- cles, as to the recti, trachelo-mastoideus, and complexus, in- osculating largely with the occipital artery : often there is at this point one large and particular artery going out to the back of the neck. Again, as the vertebral passes through the occipital hole, it gives out a little artery, which accompanies the trunk itself up through the foramen magnum, and goes to that part ofthe dura mater which covers the cuneiform process, and there it inosculates with the twig of the carotid, which enters along with the jugular vein. This is the posterior artery of the du- ra mater. Next come the arteries of the spinal marrow, the anterior of which comes out from the trunk ofthe vertebral artery ; the posterior (though it also sometimes comes off from the verte- bral before the basilar is formed) more commonly comes off from the posterior cerebelli. 1. ARTERIA ANTERIOR MEDULLiE SPINALIS. The anterior artery of the spinal marrow is the larger of the two. It was discovered first by Willis ; it had been OF THE SPINAL MARROW. 197 looked upon, till the time of Vieussens, as a nerve accompany- ing the spinal marrow; because, when empty of blood and uninjected, it is white, and not unlike a nerve. This spinal artery begins within the skull by two branches, which unite as they proceed down the. spine. These two branches arise one from each vertebral artery, at the very point where the ver- tebrals are about to unite to form the basilar trunk : each artery passes down its own side of the spinal marrow, betwixt the corpora olivaria and the corpora pyramidalia ; each artery, before it leaves the skull, gives twigs to the tuber annulare, and to the pyramidal and oval bodies, for they are the beginnings of the spinal marrow ; and soon after emerging from the skull*, the two spinal arteries join so as to form one anterior spinal artery. This joining is usually at the top of the neck, or rather within the skull, but sometimes so low as the last vertebra of the back. Almost always they join within the head or near it; and the anterior spinal artery which they form descends along the spinal marrow in a furrow which it forms for itself. The peculiar office of this artery is to supply the spinal marrow and its sheath, which it does by sending continual branches into the substance of the spinal marrow ; while other branches go into the sheath itself, and pass out from the spinal canal along with those nerves which go out from the spinal marrow, accompanied by little processes of the sheath, which are named processi denticulati. But this artery, being extremely small, would be soon ex- hausted, were it not reinforced with small arteries coming into the sheath: these pass through the vertebral interstices into the spinal canal, and are derived from every artery that passes near the spine. Thus in the neck the spinal artery receives twigs from the vertebral arteries, and from the thyroid and cervical arteries ; in the back it receives twigs very regularly from each of the intercostal arteries, and it receives its twigs from the lumbar arteries when it has got down as low as th- loins. But this spinal artery which is continually diminishing, at last fails in the loins ; and where the cauda equina begins, viz. in the canal of the os sacrum, the medulla is no longer supplied by a spinal artery, but by the small branches of the sacral ar- teries, which enter by the ten holes of the sacrum. Of those adventitious branches which reinforce the artery of the spinal marrow as it descends through the spine, each gives • The artery which accompanies the ninth pair or lingual nerve, often comes fr^m the anterior spinal artery. 198 ARTERIES OF THE EYE. several other branches ; they give twigs to the muscles of the spine, twigs to the substance of the vertebrae themselves, twigs to the sheath of the spinal marrow ; and, finally, twigs which inosculate with the spinal artery, and which sink into the ner- vous substance to nourish it. 2. ARTERIA SPINALIS POSTERIOR. The posterior spinal artery differs in all essential points from the anterior : first, there are two posterior spinal arteries which arise, not from the basilar or vertebral arteries like the anterior, but usually from the arteria anterior cerebri; and they are smaller than the anterior spinal artery: secondly, these two arteries give small twigs to the bottom of the fourth ventricle, and then go round from the fore to the back part of the medulla oblongata; but there, instead of uniting like the beginnings of the anterior artery, they continue separate, run down the spinal marrow as two distinct arteries, with very fre- quent inosculations betwixt them. This artery is also unlike the other in respect of its termination, for it disappears at the second vertebra of the loins. Its inosculations with the ar- teries from without are very free. §. 3. arteries of the eye. The arteries of the eye come from one branch only, the ophthalmic artery, the branch which the carotid, when it touches the anterior clynoid process, sends into the orbit along with the optic nerve. But small as this original artery is (no bigger than a crow-quill), the system of arteries which arises from it is very great; whether we consider their number, the irregular parts which they supply, or the great inosculations which they form even with the outward arteries ofthe nose and face. These are reasons for setting this order of arteries apart ; and even with all possible care in the arrangement, it is not easy to deliver an orderly intelligible history of this artery. The ophthalmic artery supplies not only the eye itself, i. e. the globe, but it supplies also all the apparatus, if I may so call it, of the eye, i. e. the muscles, the lachrymal gland, the eye-lids^ and even the forehead and nose. arteries of the eye. 199 1st, It sends a great branch, which leaves the ophthalmic artery, and takes its own course outwards and upwards along the eye, to supply the lachrymal gland where it is exhausted. 2dly, the ophthalmic supplies the eye itself, both by that artery which enters into the centre of the optic nerve, called arteria centralis retinae, and also by other arteries which are named the ciliary arteries ; because they go onwards to the fore part of the eye, where the ciliary circle is. 3dly, the muscles are supplied by an artery which comes from the same place nearly with those ciliary arteries. 4thly, there are two arteries which go down through holes in the socket into the bones and cavities of the nose ; and these, as they perforate chiefly the aethmoid bone, are named aethmoidal arteries. 5thly, and lastly, those arteries which go out upon the forehead and nose are so directly from the trunk of the ophthalmic artery, that they must be re- garded as the termination of it. This is the system of vessels which comes now to be described, and this is, perhaps, the best order for the description. FIRST ORDER. 1. arteria lachrymalis. The lachrymal artery is the first branch ofthe ophthal- mic ; but, in order to know its place correctly, we must first observe how the ophthalmic artery enters the eye. It comes off from the carotid, "where that artery touches the clynoid process ; and is so close upon the process, that the setting off of the ophthalmic is almost covered by that projection. It then dives under the optic nerve, and appears on the outer side of it; and as the artery goes along through the orbit, it makes a spiral turn till it completely surrounds the nerve. The lachrymal artery goes off from the ophthalmic imme- diately after entering the orbit*, though sometimes it arises from the artery of the dura mater ; and then it enters by the foramen lacerum, which is the next opening to the optic hole. It goes off from the ophthalmic about two or three lines after it has entered the socket. It goes all along the outer side of the * Sometimes it goes off one or two lines before the ophthalmic enters thc optic hole, sometimes from the middle of the artery. 200 ARTERIES OF THE EYE. orbit, because the lachrymal gland lies in the outer corner of the eye. When it reaches the gland, it is branched out and entirely expended upon it, except that it sends some small twigs forwards to the eyelid. Of these vagrant branches, one twig goes to the periosteum of the orbit, perforates the cheek bone, and so gets into the hollow of the temple, inosculating with the deep temporal artery ; while another little branch goes to the tarsus of the upper eyelid, and another to the tarsus of the lower eyelid, and thus ends the lachrymal artery. SECOND ORDER. In the second order are included the arteries which go to the eye itself, viz. the arteria centralis retinae, and the ciliary arteries ; of which arteries there is none more cu- rious than the arteria centralis retinae. 1. ARTERIA CENTRALIS RETINAE. This artery is so named because it perforates the optic nerve, runs up through its very centre or axis, enters into the cavity of the eye through the very centre of the optic nerve, and spreads its branches all over the retina. It usually arises from the ophthalmic artery, where it turns in the middle ofthe orbit over the upper part of the optic nerve* ; it plunges into the nerve ; and this artery, or rather the artery and vein, both (for the vein accompanies it) make so large a canal in the cen- tre of the optic nerve, that it stands quite open and gaping when the nerve is cut across ; and was long known to the older anatomists by the name of porus opticus, before the meaning of this orifice or hole was understood. When this artery arrives within the eye, it branches out most beautifully upon the retina. The angles and meshes which this artery makes give the name of retina or net-like to the whole ; for the pulpy7 part of the optic nerve expands into a very thin and delicate web which resembles mucus. This web has all its strength from these branches of the central artery. The branches of the artery, and the mucus-like ex- pansion of the nerve, lie in two separate layers ; and hence some anatomists reckon the retina a double membrane. • It may be found arising from the ciliary arteries, or sometimes from thc muscular. ARTERIES OF THE EYE. 201 The arteria centralis having given off sidewise these in- numerable branches to the retina, still goes forwards, plunges through the substance of the vitreous humour, does not stop till it arrives at the back part of the lens, and is of course the arteria centralis oculi, the central artery of the eye it- self. This central artery can no more be seen in the adult eye than the arteries of an unprepared bone ; but by injecting the small arteries of the eye of a foetus, of a slink Calf, or of any young animal, the arteria centralis oculi is found to distribute its branches in the following way; as it goes forwards through the centre of the eye-ball, it gives off its delicate arteries from side to side, which go along the partitions of the vitreous hu- oour (for the vitreous humour is divided every where by membranes into small honeycomb-like cells.) These cross arteries inosculate with those of the retina, and are plainly the arteries which secrete and support the vitreous humour. The central artery stops when it comes to the back of the lens : it is scattered in a radiated form, as if by the resistance, into a great many branches. These branches go round all the cap- sule of the lens, and meet again on its fore part; where, uniting into one or more small arteries, they pass onwards into the opening of the pupil, and help to form that membrane which in the fcetus shuts out the light, protects the ey7e, and vanishes very gradually. So the arteria centralis retina passes first dirough the centre of the optic nerve ; next through the centre of the vitreous humour ; next, after going round the capsule of the lens, it passes through the posterior chamber of the aqueous humour, and terminates in the centre of the pupil. JBut as these last arteries, viz. of the pupil, vanish soon after birth, we may consider the central artery as ending in inosculations with those arteries, which coming upwards along the sides of the eye along with the retina, form a strong circle of arteries at the root of the ciliary process. 2. arteria ciliares. The ciliary circle is known, upon looking outwardly at the eye, by that white line which borders the iris, and separates the iris or coloured part of the eye from the white or colourless part. That circle marks the place where there is a great concourse of arteries. The corpus ciliare, or ciliary body, is the part within the eye which lies flat upon the fore part of the vitreous and crystalline humours, which is like a second iris behind the first, which is extremely vascular, and corresponds with the Vol. II. 2 C 202 ARTERIES OF THE EYE. ciliary circle without. This corpus ciliare is radiated (that is a consequence of the peculiar order and arrangement of its ves- sels, which run in rays from the ciliary circle, u e. from the circumference towards the centre.) These radii coming from the ciliary circle are called the ciliary processes ; so that the ciliary circle, corpus ciliare, and ciliary processes, are all parts of the same vascular organ. This is the part of the eye to which all those arteries go which are next to be described. 1. Two arteries of considerable size go off. from the sides of the ophthalmic artery-: these go along the sides of the optic nerve ; they go towards the bail of the eye ; and the one on the outer side of the eye is named external ciliary arte- ry, that on the inner side of the optic nerve is named the in- ternal ciliary. 2. These two divide themselves again into two subordinate branches : one of them as soon as it touches the eye, that is, just beyond the implantation of the optic nerve, enters its sub- stance, and is spread out on its choroid coat in a great number of branches, which are named ciliares breves, the short ciliary arteries : the other goes further forward upon the eye before it enters, and even after it enters it still goes forwards to the very fore part of the eye before it divides ; hence named CILIARES LONG.E. 3. The anterior ciliary arteries are some small and uncertain branches, which come sometimes from one source, sometimes from another, but most commonly from the muscu- lar branches ; and they go along with the muscles, and conse- quently enter the eye at its fore part just where the recti mus- cles are inserted. But, though small, these anterior ciliary arteries are of considerable number. From the places at which these several arteries enter the ball, one might guess a priori how they will be distributed through its coats. First, The short ciliary arteries do not all of them arise from the ciliary trunk ; but of this great number of very small arteries, many arise from the muscular branches. As soon as they touch the eyeball, they enter into it near the in- sertion ofthe optic nerve, pass through the sclerotic coat, leav- ing for its nourishment a few twigs ; they divide so, that just after they have entered, we can count twenty-five or thirty all round the root of the optic nerves, which go forwards in a ra- diated form, and are completely diffused upon the choroid coat, which they cover with an inner membrane, or rather tissue of vessels, named tapetum, or tunica Ruysehiana. This coat of vessels lines the choroid all the way forward to the lens, goes still onwards to the fore part of the lens; and ARTERIES OF THE EYE. 203 then turning down upon the lens at right angles, it meets with the anterior vessels, and forms the ciliary circle, and the ciliary processes or radii, which are about thirty ; so that the short ciliary arteries having formed about thirty branches in entering at the back part, they now terminate by a like number at the fore part of the eye. A few twigs go still forward upon the uvea and iris, so as to make a very important connection of all the vascular parts of the eye. Secondly, The longer ciliary arteries enter the scle- rotic a litde further forward, penetrate at a greater distance from the optic nerve, they penetrate the sclerotic a little before its middle; but still they continue entire, or they give but very small branches. When they approach the ciliary circle, they divide into two or three long arteries, which go off at right an- gles, embracing a corresponding quarter ofthe ciliary circle : from these arms their branches meet each other, and are now joined both by the shorter ciliary arteries and by the anterior ciliary arteries; by which conjunction an arterial circle is form- ed which corresponds with the outer circle ofthe uvea, and is called the outer ciliary circle : this again sends radii of vessels, perhaps thirty, inwards, which meeting form a second circle, the inner ciliary circle. Thirdly, The anterior ciliary arteries again enter the eye at its forepart, and immediately unite with these, as has just been explained ; they help to form the ciliary circle, which is the great conjunction of all the internal vessels of the eye. © THIRD ORDER. In this order are included the muscular arteries, which are the least regular of all the branches of the ophthalmic arte- ry. From one or other branch of the ophthalmic there ge- nerally arise two muscular arteries ; the one for the upper, the other for the lower muscles. 1. ARTERIA MUSCULARIS SUPERIOR. The upper muscular artery consists of small twigs, which go chiefly to the levator palpebrae and rectus superior ; and these, though they sometimes arise as two small twigs from the ophthalmic artery itself, yet in general come off ra- 204 ARTERIES OF THE EYE. ther from that artery which, as it goes out by the supra-orbita- ry hole, is named the supra-orbitary artery. These muscular branches ofthe supra-orbitary, then, supply the upper muscles of the eye, as the levator palpebral, the obliquus major, the rectus superior, and the sclerotic or outer coat ofthe eye. 2. ARTERIA MUSCULARIS INFERIOR. The lower muscular artery is very generally an inde- pendent artery, and prettyTarge. It comes off from that part ofthe ophthalmic artery where it is giving off the ciliary arte- ries*. This muscular branch is large enough to give off some- times the arteria centralis retinae, and often some of the short ciliary arteries arise from it; it is so long as even to reach the lower eyelid. The muscles which it supplies are all those which lie on the lower part of the eye, as the deprimens oculi, abducens oculi, obliquus minor. It also gives variable twigs to the sclerotica, the optic nerve, the periosteum of the orbit, and sometimes to the adnata and lower eyelid. .&< FOURTH ORDER. The set of arteries which stand next in order are those which go down into the nose through the aethmoidal bone, whence they are named aethmoidal arteries. The aethmoidal arteries are, like the other branches of the ophthalmic, pretty regular in their destination, but far from being regular in the manner in which they arise. 1. ARTERIA jETHMOIDALIS posterior. The posterior ^ethmoidal artery is so named because it passes through the posterior of two holes which are in the or- bit at the joining of the aethmoidal with the frontal bone.* It is an artery by no means regular in its place, coming some- times from the ophthalmic trunk, sometimes from the lachiy- mal artery, very rarely from the supra-orbitary artery. It is ' In describing thc skull, these arc named the internal orbitary holrs. arteries of the eye. 205 of no note : it is the smaller of the two aethmoidal arteries; it goes through its hole, and is scattered upon the bones and mem- branes of the nose. While it is circulating its twigs among the aethmoidal cells, it inosculates, of course, with the nasal arteries ofthe external carotid. 2. ARTERIA jETHMOIDALIS ANTERIOR. The anterior aethmoidal artery is rather more regular and more important; it passes through a larger hole, and is itself larger; it comes off more regularly from the ophthalmic trunk, and it goes not down into the nose, but upwards into the skull. The "ophthalmic artery, much exhausted by giving off many branches, has risen over the optic nerve, has completed its spiral turn, and has just got to the inner corner ofthe eye, where the aethmoid hole is, when the anterior aethmoid artery arises from it. It arises just behind the pulley of the upper oblique muscle, plunges immediately into its peculiar hole, and, passing along a canal within the aethmoid bone, it merely gives twigs to the frontal and aethmoidal sinuses, and passes up by one of the largest holes in the cribriform plate of the aeth- moid bone. When within the skull, it is under the dura ma- ter, betwixt it and the bone ; it goes to the dura mater and to the root of the falx, and some of its delicate twigs turn down- wards again into the nose, through the small holes of the cri- briform plate accompanying the branches of the olfactory nerve. FIFTH ORDER. The fifth order of arteries is very numerous, including all those which send their twjgs outwards upon the face. They are the supra-orbitary artery, the artery of the upper eyelid, the artery7 of the lower eyelid, the artery of the forehead, and the artery of the nose. 1. arteria supra-orbitalis. The supra-orbitary artery is so named from its emerging from the socket by that notch in the superciliary ridge which 206 ARTERIES OF THE EYE. we call the supra-orbitary hole. It comes off from the ophthal- mic artery at the place where it gives off the ciliary and lower muscular arteries: it so often gives off the arteries which go to the upper muscles of the eye, that some have named it the su- perior muscular artery. It passes onwards, giving twigs to the levators of the eye and of the eyelid, and to the upper o- blique muscles, and to the periosteum ; and before it arrives at the supra-orbitary hole, it divides into two twigs ; of which one lies deep, and supplies the periosteum of the forehead, in- osculating with the temporal artery ; the other lies more su- perficial, but still is covered by the orbicularis and corrugator supci ciin, on which muscles it bestows all its branches. 2. arteria palpebrales. The two palpebral arteries arise from the ophthalmic after it has passed the tendon of the obliquus superior, when it has in a manner emerged from the socket, and is lying at the inner angle of the eye : there it commonly gives off two small arteries, one to the upper and one to the lower eyelid ; and often the two arise by one trunk. Arteria palpebralis inferior.—The artery of the lower eyelid is the branch of the two which goes off the first; but it is the smaller and less regular of the two. Its twigs go one to the union of the two tarsal cartilages, to the caruncula .lachrymalis, and to the adjoining part of the adna- ta ; another goes deeper, viz. to the lachrymal sac, and even into the aethmoid cells ; and a third twig runs along the margin of the tarsus, named tarsal artery, supplying the Maibomian glands. Arteria palpebralis superior.—The artery of the upper eyelid arises along with the lowerpalpebral or near it; it gives few branches ; one keeps to the angle of the eye, and supplies the orbicularis oculi, the caruncula, and the tunica conjunctiva; another having pierced the fibres ofthe oblique muscle, runs along the borders of the tarsus, inosculating with a similar branch of the lachrymal artery, and forming an arch along the upper tarsus as the other does below. 3. ARTERIA NASAL IS. The nasal artery joes off at the edge of die orbit, rises over the lachrymal S3 , and over the ligament of the eyelids: it first gives a twig upwards to the root, of the frontal muscle ; arteries of the eye. 207 then another goes down over the lachrymal sac, and after giv- ing branches to the sac, goes to the orbicularis muscle, and in- osculates with the infra-orbitary artery ; and lastly, the most remarkable branch of this artery, from which indeed it has its name, runs down upon the side of the nose, making a beauti- ful net-work, and inosculating with the last branch ofthe labi- al artery which runs up to meet it.* This is quite a cutaneous artery ; many of its twigs go the skin ; it is felt beating strong- ly ; it was often opened when arteriotomy was more regarded than it is now. 4. ARTERIA FRONTALIS. The frontal artery is now to be distinguished from the supra-orbital; for the supra-orbital rises deep in the socket, emerges by the supra-orbitary hole, passes along chiefly be- twixt the bone and muscles, and makes no remarkable figure upon the face : while this, the frontal artery, is larger, keeps chiefly upon the surface ofthe muscles, is quite subcutaneous, has nothing to do with the supra-orbitary hole, and rises beauti- fully upon the forehead. It is a delicate and slender artery, not so large as the nasal, and looks like one of its branches ; it gives off first a branch to the eyelids, named superciliary arte- ry, which supplies the root ofthe frontal and the upper part of the orbicularis muscles ; it sends an ascending branch which dives under the frontal muscle, and belongs chiefly to the os frontis and pericranium. This is the little artery which often makes a perpendicular groove in the os frontis. The chief branch of the artery continues subcutaneous, is felt beating along the forehead, belongs chiefly to the skin ofthe forehead and to the hairy scalp, and mounts to the top ofthe head, to the place of the fontanelle, where it has free inosculations with the temporal artery. This last branch is the end of the ocular or ophthalmic arte- ry, of which the branches are so irregular in their origin, that the most diligent anatomists have declined that part of the de- scription, and yet have arranged the branches upon that scheme, viz. the points from which the several twigs arise: whereas I have thought it more prudent, since the branches are regular in respect of the parts which they supply, to ar- range them according to those parts, viz. the lachrymal gland, the eyeball, the muscles, the aethmoid -ells, the face ; an order • Some of its branches absolutely penetrate the Cartilages of the nose, and so get access to the Schneiderian membrane, and supply i: with blood. 208 ARTERIES OF THE BRAIN. which also very nearly corresponds with the order in which the arteries arise. The learning and remembering these arteries, it is right to acknowledge, is a task more difficult than useful ; more suiting the severe anatomist, than the practical surgeon ; who yet, if he do his duty, will learn all; and as he learns much, must expect to forget much. CONCLUSION. Before I leave this difficult subject, I stop one moment to explain a point which might leave some confusion in the rea- der's mind ; and regarding chiefly those little arteries which belong to the membranes of the brain. It is of great importance in studying the brain, to know the manner in which its membranes are connected with it; and it is especially to be remarked that the internal surfaces, or, in other words, the cavities of the brain, need to be supported, nourished, and supplied with blood as much as the external surface ; and that for this end the pia mater turns inwards and lines all the cavities ofthe brain. At different points the pia mater and its arteries take vari- ous forms, and are called rete mirabile, velum, or cho- roid plexus, according to that form. The rete mirabile has already been explained, as being that division and reunion of the branches of the carotid artery by which the force of the ascending blood is broken before it enters the brain. In many ofthe lower animals this provision of Nature is most curious and particular; but in Man it would appear, that the erect posture in which he walks, the contor- tions of the carotid artery as it enters the skull, the manner in which it lies in the cavernous sinus, and, finally, the minute division which it undergoes by spreading over the pia mater before it enters the brain, are sufficient. In Man there is not the smallest vestige of a rete mirabile : and whenever we find a rete mirabile described in Man (as often it has been described,) we find invariably that it means no more than the plexus of delicate vessels which go out from the first twigs of the carotid artery, either to supply the membranes or to enter into the ca- vities of the brain ; and accordingly we find these authors call- ing it " a beautiful beginning of a rete mirabile ;" " an imper- fect rete mirable," Sec. The velum, as it is called, is that netted form which the arteries of the brain. 209 pia mater assumes often about the basis of the brain, whene- ver the smaller arteries are numerous ; for the inosculations of the arteries are like a net-work ; the arteries, full of blood or of injection, are opaque and are very apparent; while the mem- brane upon which they run is lucid, diaphanous, and is scarce- ly seen. A velum or net of this kind appears on every smooth and uniform surface of the basis of the brain ; but the most re- markable of all is that which lies betwixt the brain and the ce- rebellum. It is named velum interpositum ; and at this place insinuates itself (betwixt the brain and the cerebellum) into the back part of the lateral ventricles, where it covers the nates, testes, and pineal gland. The plexus choroides again is merely another variety or form of the pia mater. The great choroid plexus is a mem- brane which lies upon the bottom of each lateral ventricle : it is netted and extremely vascular, not unlike the chorion of some animals, whence it is named. It consists partly of arte- ries, but chiefly of veins ; it conveys some blood to the inter- nal surfaces of the brain, but returns much more. But although the choroid plexus of the two lateral ventri- cles be the chief one, the third and the fourth ventricles have each their plexuses or vascular webs. The chief points by which these vascular webs of the pia mater enter are by the anterior and posterior horns ofthe lateral ventricles ; at which points, and indeed at all the lower parts of the brain, the ven- tricles must be considered as shut, since these vascular linings, as they enter, adhere on all sides : but may also be considered as open, since they admit these membranes, since they are shut only by their slight adhesion, and may be opened by pull- ing the parts gently asunder. This, then, is a general explanation of that vascular part ot the pia mater which covers all the basis, and lines all the ca- vities of the brain. It is one continuous membrane, under the various titles of rete mirabile, which some older anatomists use ; of velum, a name chiefly repeated by Haller: and of plexus choroides, a name universally used for that net-work ot vessels, which lies out upon the floors of the ventricles. It will be seen hereafter how greatly a knowledge of these inflec- tions contributes to the right understanding of the brain and its parts and cavities. Vol. II. 2 D ( 210 ) CHAP. II. OF THE ARTERIES OF THE ARM. L he subclavian arteries arise from the arch of the aorta. The left subclavian arises from the extremity of the arch, and just where the aorta is turning down towards the spine. It is longer within the thorax, runs more obliquely to pass out of the chest, receives in a less favourable direction the current of the blood. But the right subclavian arises from the aorta by that artery which is called the arteria innominata ; for it is ' an artery which can have no name, being neither the carotid nor the subclavian, but a trunk common to both. It is large, rises from the top of the aortic arch, receives the blood in the most direct manner ; from which physiologists have deduced those consequences which have been already explained*. The artery of the arm, as it proceeds, changes its name ac- cording to the parts through which it passes. It is named subclavian within the breast, axillary in the arm-pit, brachial as it goes down the arm, and when it divides at the bending of the arm, its two branches are named the radiel and ulnar arteries, after the radius and ulna, along which they run, until at last they join to form vascular arches in the palm of th* hand. Nature has thus arranged and divided the parts of this ar- tery ; and the study of its branches becomes easy to those who will first condescend to observe this simple arrangement and the parts through which it goes. 1st, While the artery is within the breast, it lies transversely across the root of the neck ; it supplies the neck, the breast, the shoulder ; it gives all its branches upwards into the neck, or downwards into the breast: upwards it gives the vertebral to the inside of the neck (if I may use an expression which cannot now be misunder- stood) ; the cervical, which goes to the outside ofthe muscles of the neck ; the thyroid, which goes to the thyroid gland. While it gives off from its opposite side downwards, and into the chest, the mammary, which goes to the inner surface of the breast; the upper intercostal artery which serves the space betwixt the uppermost ribs; the mediastinum and pericardium; * Douglas says the left is shorter, which 1 can by no means understand. arteries of the arm. 211 and even the diaphragm, though far distant, receives branches from this mammary artery. 2. When the artery, having turned over the sloping part of the chest, glides into the axilla, and lies deep there betwixt the scapula and the thorax, what parts can it supply, or what vessels can it give off, but scapular and thoracic arteries ? Its branches accordingly are three or four slender arteries to the thorax on one hand, named the four thoracic arteries, which give twigs to the glands, the pectoral muscles, and the breast or mamma ; and on the other hand it gives off first great arti- cular arteries which surround the joint, and still great scapular arteries which surround the scapula, and nourish all that great mass of flesh which lies upon it. 3. But when this artery takes the name of the humeral ar- tery, and passes along the arm, it must be simple, as the arm is simple ; for it consists of a bone of one mass of muscles be- fore and another behind: the artery of course runs along the bone undivided, except that it gives off one branch, which runs parallel along with the main artery, and which running deeper among the flesh, is named muscularis or profunda. 4. It divides at the bend of the arm, in order to pass into the fore-arm in three great branches. In wounds thus low, all danger of losing the arm from wounds of the artery, unless by the gross ignorance or fault of the surgeon, is over; we do not attend so much to the parts which it supplies, or, in other words, to its inosculations, as to the parts against which the 0 great branches lie. We observe here, as on all occasions, the artery seeking protection, and running upon the firmest parts : its three branches now pass ; one along the radius, another along the ulna, a third along the interosseous membrane. 5. In the palm of the hand we find the artery still following the order of the bones ; and as the carpal bones are as a centre or nucleus, upon which the metacarpal and finger-bones stand like radii, the palmar artery forms a complete arch, from which all the fingers are supplied by arteries, issuing in a ra- diated form. Of all these subdivisions the subclavian artery is that which seems the least important to know ; and yet without a perfect knowledge of it, how shall we understand many important arteries of the neck or shoulder ? How shall we understand the anatomy of the greatest of all the nerves, viz. the sympa- thetic nerve which twists round it ? How shall we judge rightly of tumours near it, or of aneurisms which so often mount along this artery from the arch of the aorta until they are felt here ?----Of the second division of the artery, viz. where it lies in the axilla, the importance is most unequivocal: 212 ARTERIES OF THE ARM. since every attempt to stop haemorrhagies, by compressing this artery, requires a knowledge of it; since every full bleeding wound near this place alarms us, and requires all our know- ledge : since every tumour that is to be extirpated opens some of its branches ; since we cannot cut off a cancerous breast, or the glands which should be taken along with it, without cutting the thoracic arteries.—Next, the artery of the arm, simple as it is, interests us greatly. It is this simple artery which is hurt in aneurisms; it is its delicate, I had almost said capillary7, branches, which are to establish a new circula- tion, and to save the limb. We have indeed no apprehensions of losing the limb for want of blood (the continual success of our operations having established this point) ; yet it is most in- teresting to observe the extreme smallness of these branches, as an assurance to us in other cases of danger ; though I do indeed believe, that there cannot in any simple wound in any limb be the smallest danger from this much dreaded obstruc- tion of the blood. The arteries of the fore-arm are more interesting still; for if we will be so selfish as to consider the difficulties of the sur- geon merely, wounds of the arteries in the fore-arm are very- distressing. These arteries lie deep among the muscles, drive their blood (when wounded) through the whole arm, and either occasion a difficult and most painful dissection, or cause a deep and gangrenous suppuration ; so that whether the sur- geon be so dexterous as to secure the arteries, or so timid as to leave the arm in this woeful condition, the patient is to undergo such sufferings by pain, or by a long disease, as must interest us greatly. The arteries even of the wrist and hand, though small, are important. The difficulty of managing wounds of these ar- teries stands buritoo often recorded in all kinds of books for us to doubt the faacui If many have died after frequent bleedings from these aitewvimtiiough under skilful hands, what ought we not to submit to u. the way of study and labour to acquire and to retain a knowledge of these arteries ; since by that alone every thing that is surgical in tumours, aneurisms, amputa- tions, is well or ill performed according to our degree of know- ledge ; and since, according to our degree of knowledge, we are disengaged in our minds, and have free possession of our judgment, to do any thing which may7 be required ? In short, as we proceed along this artery, we shall perceive that each division of it rises in importance ; or at least, that if wrounds about the axilla be more d mgerous, they are proportionably rare. ; that if accidents about ihe wrist or hand be less danger- OF THE SUBCLAVIAN ARTERY. 213 ous, they are, however, more frequent, so as to deserve every degree of attention. I. OF THE SUBCLAVIAN ARTERY. This artery is so named from its passing under the clavicle by which it is protected ; and we include under this division all that part of the artery which lies betwixt the arch of the aorta and the outside of the clavicle, where the artery comes out upon the chest. Here the artery is of a very great size; it lies directly across at the top of the chest, and root of the neck ; and like a cylinder or axis, it gives its branches directly upwards and directly downwards to the throat, to the neck and the parts within the chest. Upwards it sends the verte- bral, the thyroid, the cervical, and all the humeral arteries ; downwards it sends the upper intercostal artery, and also the internal mammary, which, besides its going along the inner surface of the chest, gives branches to the pericardium, medi- astinum, thymus, and other parts. 1. ARTERIA MAMMARIA INTERNA. The internal mammary artery is the first which the subclavian gives off; it is of the size of a crow-quill, long, slender, its ramifications very beautiful. On each side of the chest the mammary artery passes down along all the inner sur- face of the sternum, and ends at the carti^Vo ensiformis in numerous inosculations with the epigastri- l ry ; for the epi- gastric arises from the femoral at the rtPV%, ^just as this does from the subclavian at the top of the c .lest, and runs upwards along the belly, as this the mammary runs downwards along the breast till they meet each other midway. This is an inos- culation, which fifty years ago was much noticed. Physiolo- gists deduced the most important consequences from it, ascribe ing the connection of the breast and womb to the flux and re- flux, to the alternate stoppage and acceleration of the blood in these vessels ; although the sympathy of the breasts and womb is plainly a connection which Nature has established upon other laws, upon a kind of sympathy such as we see every where in the system, but can in no instance explain. The course of the mammary artery and the order of its 214 OF THE SUBCLAVIAN ARTERY. branches, is this : it goes off from the lower and fore part of the axillary artery ; it lies on the outside of the membranous bag ofthe pleura ; and considering the pleura as ending in an obtuse and rising apex, the mammary artery lies at first a lit- de behind the pleura, its first movement is to rise and turn with an arch over the top of the pleura or bag which incloses the ca- vity of the ch. st ; there it descends again, and passes betwixt the ribs and pleura; the artery runs along the inside of the thorax under the middle of the cartilages. At the seventh or eighth rib the mammary itstlf emerges from the thorax, and becomes an exu-rn:d artery ; it first sends a branch towards the ensiform cartilage,* which plays round it, and then it goes to the upper part of the abdominal muscles by two distinct branch- es, the one of which is internal, the other external. The inter- nal branch goes ivto the belly or substance of the rectus mus- cle, descends nearly as far as the navel, and inosculates with the epigastric artery. The external branch turns off to one side, goes rather to the lateral muscles of the abdomen, especi- ally to the two oblique muscles, and it inosculates more with the lumbar arteries ; and so the mammary ends. But as it passes down along the chest, it gives the following branches : First, Where it is passing the clavicle, bending to go down- wards, it gives a small retrograde branch which follows the course ofthe clavicle, and goes to the muscles and skin of the neck.* Secondly, It gives on artery, or rather arteries, to the thy7- mus arteria thymic*:. These are in the adult extremely small, because the gland itself is so ; but in the child the gland is large, the upper part lies before the trachea, the lower part lies upon the heart, or rather upon the pericardium betwixt the two lobes of the lungs : the upper end then is supplied by the thyroid artels ; the middle part is often supplied by a distinct and particular branch, viz. by this arteria thymica coming from the nummary, but this is far from being always so ; the lowest part of the gland has twigs from those arteries which properly belong to the mediastinum, upon which it lies, or to the pericardium or to the diaphragm. Thirdly, The mammary gives also the upper artery of the diaphragm, its lower artery being the first branch of the aorta within the abdomen. This upper artery of the diaphragm is named arteria comes nervi phrenici, because it accompa- nies the phrenic nerve. The phrenic nerve is passing from * Sabbatier is so confused, and copies Haller so ill, that he mistakes this for thr. transversalis humeri, which is really an important artery. OF THE SUBCLAVIAN ARTERY. 215 the neck (where it arises) into the chest, by the side of the ax- illary arteiy, when it receives from the mammary this small ar- tery which goes along with it; and this artery, which is so extremely small that nothing but its regularity can give it any importance, goes down through the whole chest, accompany- ing the phrenic nerve over the pericardium till they arrive to- gether on the upper surface of the diaphragm, and spread out there. This artery, small as it is, gives twigs as it passes a- long to almost all the parts within the chest. Fourthly, The mammary gives an artery7 to the pericardi- um, which may be called the upper pericardiac artery j and which is of such importance, that generally when it does not come off from the mammary, it comes from the subclavian itself, or even from the aorta. It belongs to the upper and back part ofthe pericardium. Fifthly, The pericardium has another artery from the mam- mary, which belongs to that part of the heart which is united to the diaphragm: it is thence named by some arteria phre- NICO-PERICARDIACA. Sixthly, The mammary gives many small arteries to the mediastinum ; for the mammary is covered only byr the sterno- costalis muscle, which is often hardly visible in Man, so that the artery may be said to lie upon the pleura, betwixt it and the ribs. The mediastinum is just that doubling of the pleura which descends from the sternum to the spine, and of course many small arteries go down from the lower surface of the sternum along the pleura into the mediastinum, and by that to the pericardium, or even to the membrane of the lungs ; for the pericardium is one inflection of the pleura and mediastin- um, and the covering membrane of the lungs is another. The mammary, as it goes downwards, sends branches through the interstices of the ribs ; two twigs pass through each interstice, going to the intercostal muscles, and to the muscles which lie upon the thorax, as the pectoral muscles ; also to the mamma, to the obliquus externus abdominis, and to form loops of inosculations round the ribs with the proper intercostal and thoracic arteries. These twigs pass through the interstices of the six or seven upper ribs, but at the seventh the artery itself comes out. They are too numerous and too small to be either counted or named. Seventh, The mammary, before it terminates in the two branches, of which one keeps the middle and goes to the rec- tus muscle, while the other goes outwards to the oblique mus- cle, as already described, gives about the place of the sixth rib a branch which in place of passing out of the thorax, keeps to its inner surface, goes downwards along the seventh, eighth, 216 OF THE SUBCLAVIAN ARTERY. and ninth ribs, makes its inosculations there with the intercos- tal and other arteries, and ends in the side of the diaphragm, and in the transverse or innermost muscle of the abdomen, which indigitates, as we call it, with the diaphragm. From this destination it is sometimes named the ramus musculo- phrenicus. 2. ARTERIA THYROIDEA INFERIOR. The lower thyroid artery, whose branches go to the neck, the shoulder, and the thyroid gland, arises from the fore part ofthe subclavian artery, close upon the origin ofthe internal mammary. It is there covered by the root of the ma- stoid muscle. It buds out from the root of the great axillary artery, in the form of a short thick stump, which immediate- ly divides whip-like into four small and slender arteries. 1. The main branch of this artery is again named the ramus thyroideus arteriae thyroideae. This thyroid artery is the first great branch ; it does not ascend directly, but moves a little inwards towards the trachea, from which the root is a good deal removed : it bends behind the carotid artery, is tortuous, ascends by the side of the trachea till it touches the lower lobe of the thyroid gland : it spreads upon it like a hand, inoscu- lates very freely with the upper thyroid artery, and nourishes the gland. This branch moreover gives some twigs upwards to the lower constrictors of the pharynx and to the oesophagus; but its chief arteries, beside those which plunge into the gland, are its tracheal arteries. These tracheal arteries, two or three in number, are reflected along the trachea, turn down with it into the chest, and reach even to the bifurcation of the trachea, where, inosculating with the intercostal arteries, they form a most beautiful net-work. 2. The ascending thyroid artery, or thyroidea ascendens, is a small and delicate branch, which lies pretty deep, going off rather from the back part of the artery ; it supplies all the deep parts of the neck, and even penetrates the vertebrae ; it soon divides into an irregular number of branches ; the artery keeps almost close to the naked vertebrae lying under most of the muscles ; its general tendency is upwards, surrounding the neck in a spiral form. Its chief twigs are, first, some which go towards the surface, i. e. to the muscles which lie over the ar- tery, as to the scalenus, the mastoid muscle, the levator sca- pulae, and the splenius ; and twigs of this artery play over the rectus capitis and the anterior surface ofthe vertebrae, and at- tach themselves to the eighth pair of nerves, and to the gangli- OF THE SUBCLAVIAN ARTERY. 2U on of the sympathic nerve. Its deeper arteries again go to the mtertransversarii and other muscles which lie closer upon the neck ; and these are the branches which pass in through the intervertebral holes, and penetrating the sheath of the spinal m irrow, and following its nerves, inosculate with the spinal an^ries. 3. The transverse artery ofthe neck, or transversalis colli, is an artery of the same kind with the last, viz. chiefly destined for the muscles, but more superficial. It passes obliquely round the neck outwards and upwards, goes under the trape- zius muscle, and covered by it sends branches as far as the oc- ciput. Its twigs are distributed thus : first to the mastoid muscle and to the skin ; next to the trapezius, levator scapulse, and splenius ; then a long branch passing obliquely upwards over the splenius, and under cover of the trapezius, gives twigs to those muscles, and ends in inosculations with the lower branches of the occipital artery ; and lastly, another branch goes downwards towards the scapula and shoulder. 4. The last branch of this artery is the transversalis hu- meri ; an artery so important in its destination, and so irregu- lar in its origin, and so frequently arising as a distinct and par- ticular branch, and having so little relation to these trivial branches of the thyroid artery, that I shall describe it by itself*. 3. ARTERIA VERTEBRALIS. The vertebral artery arises next from the upper part of the subclavian artery ; and running upwards and backwards but a little way, it plunges into the hole destined for it in the verte- brae : and it has been already described through all its course both within the bony canal and within the brain. 4. ARTERIA CLAVICALIS PROFUNDA. The deep cervical artery comes next in order ; it is gener- ally the least important of all the branches from" the subclavian artery, and the least regular in its place. It often comes from some other branch, and often it is entirely wanting ; its course resembles a good deal that of the transversalis colli, i. e. it goes to the deepest muscles of the neck, and to the vertebrae, and ends about the occiput; it usually arises from that part of the subclavian artery where it is just going to pass, or has al- ready passed, betwixt the scaleni muscles. lis branches are Vbj.f II. 2 E 218 OF THE SUBCLAVIAN ARTERY. few in number, it gives branches to all the scaleni muscles ; others also which play over the anterior surface of the verte- brae and the deep muscles of the neck, as the spinalis colli, in- tertransversarii, the root of the splenius and trachelo-mastoi- deus ; the complexus also receives a branch which usually in- osculates with the occipital artery. 5. ARTERIA CERVICALIS SUPERFICIALIS. The superficial cervical artery is still less regular, being very often supplied by the thyroid. Its course is direct- ly the reverse of the last, running rather outwards and down- wards, or in other words, belonging rather to the shoulder than to the neck. The subclavian artery has got from under the muscles, and has passed the splenii a little way before it gives off this superficial cervical. This artery immediately attaches itself to the plexus ofthe brachial nerve, and is indeed hidden in the plexus: its first branch is given to the plexus, but its next and chief branch goes across to the top of the shoulder ; it sends branches to the levator scapulae, trapezius, and even to the skin ; while a deeper branch goes to the sple- nius and complexus, where these muscles arise in the neck ; and when this artery is large, it sends branches along the mar- gin of the scapula, which go even to the serratus major, rhom- boides, latissimus dorsi, &c- <&< After enumerating these jarring names, I perceive the necessity of arranging once more those arteries which go to the neck. Let the student then observe, 1. That the verte- bral artery goes to the brain, that the cervical arteries belong to the muscles of the neck. 2. That the thyroid gives two ar- teries to the neck, the thyroidea ascendens and the transversa- lis colli. 3. That when a second set of arteries for the neck begins to be enumerated, the name is changed ; that of colli is dropped, and that of cervicis adopted. 4. That as there are two branches of the thyroid going to the neck, viz. the ascen- ding thyroid and the transversalis colli, there are also two en- tire arteries going to the neck, and which come off immediate- ly after the thyroid, viz. the cervicalis profunda more constant, and the cervicalis superficialis which is less regular. OF the subclavian artery. 219 6. ARTERIA intercostalis superior. The upper intercostal is given to supply the intercostal ' space betwixt the two uppermost ribs, because the aorta which gives out all the other intercostals, regularly one for each rib, does not begin to give them off till after it has made its turn downwards ; of course it leaves the two upper ribs without arteries. To supply this, then, is the office of the superior intercostal artery, which is about the size of a crow-quill, and goes off from the subclavian generally next after the vertebral and thyroid arteries. It comes from the upper and back sur- face of the subclavian trunk ; it turns downwards and back- wards and lodges itself by the side of the spine in the hollow where the spine and the first rib are joined, and where the first thoracic ganglion of the great intercostal nerve lies. Be- fore it takes its place betwixt the ribs as the intercostal of the two upper spaces, it sends a branch upwards upon the face of the lower vertebrae of the neck, which is given to the scaleni, to the longus colli muscle, and to the nerves ; next it gives off the highest intercostal artery for the space betwixt the first and second ribs, which artery divides into two branches ; one per- forates the thorax, and goes out upon the back, and supplies the muscles which lie flat upon the back of the chest; while another branch, the proper intercostal branch, runs along be- twixt the ribs. Next it gives off a second intercostal artery, which also has its external and internal branches, and of which a branch inosculates over the third rib with the uppermost in- tercostal of the aorta. Besides these, it gives also sm.ill branches to the oesophagus, which inosculate with the tracheal arteries ; and it gives branches to the spinal marrow, which pass into the canal along the holes for the nerves ; and which not only supply the sheath, but also inosculate with the arteries of the spinal marrow itself. 7. arteria supra-scapularis. The supra-scapular artery, or the superior scapular ar- tery, is one of such magnitude, is so different in size and destination from the cervical and other small arteries of the neck, that it ought to be described apart ; though of great size and importance, it is yet so little known, that Sabbatier does not even describe nor name it. The supra-scapular artery very often comes off from 220 OF THE SUBCLAVIAN ARTERY. the thyroid artery ; in which case it is tne last in order of all the branches of the thyroid, that is .o s.e,, the nearest to the shoulder, and then it is named transversalis humeri, be- cause of its going across the root of the neck to the shoulder. Sometimes ii arises from the cervicalis superficialis ; but then it is a small artery, and I suspect it reaches in such cases no further than the tip of the shoulder, and does not descend to the scapula. Often I see it arising as a distinct artery, large, very long, tortuous like the splenic artery, and almost equall- ing it in size ; running across the root of the neck, till at the top of the shoulder it dives under the acromion process ; and then passing through the notch of the scapula, supplies all the flesh of its upper surface. The reason of my naming it supra-scapular artery, is its passing thus over the scapula, while another, the largest branch of all those proceeding from the subclavian artery, is named subscapularis, from passing under the scapula. To repeat the origin then of this supra-scapular artery, it arises sometimes as an independent artery, and is so great, that we wonder that it does not always do so : often it arises from the thyroid, is its last branch, and is named transver- salis humeri, authors not observing that it belongs absolutely to the scapula; it rarely arises from the cervicalis superficialis ; and when it does so, it is small: often in a strong man it arises apart ; and when it does arise from the thyroid or cervical arteries, it is so large as to annihilate as it were all the otiier branches of the artery from which it arises. Where this artery passes out of the chest it is covered only by the root of the mastoid muscle ; and it gives twigs to the mastoid, to the muscles which ascend to the throat, to the subclavian muscle, to the fat, jugular vein, and skin. Next it gives a superficial branch to the skin, trapezius, and other superficial parts about the shoulder. Next it turns over the acromion process, passes through the supra-scapular notch, with many windings and contortions ; spreads itself over all the outer surface of the scapula, both above and below the spine, and is the sole supra-scapular artery. The manner of its spreading is this ; having passed through its hole in company with the supra-scapular nerve, the instant that it has passed the hole and begins to lie flat upon ihe_ scapula, it sends off two branches, one on either hand at right angles ; and of these one goes along the upper border of the scapula towards its basis, the other goes in the other direction towards the shoulder-joint, and circles round the upper side of the spine or ridge of the scapula. The main artery having first perforated the scapular notch. OF the axillary artery. 221 and given these two small branches, next makes a second per- foration, viz. by passing under the root of the acromion pro- cess ; and then it again divides into large branches, in which it ends. The one branch runs all along the root or base of the spine or high ridge ; the other branch runs nearly in the same direction, but lower down, viz. nearer that edge where the great subscapular artery runs ; and with which, of course, it makes many free inosculations. This artery lies so across the neck that it may be cut, espe- cially in wounds with the sabre ; and in a big man it is of such size as to pour out a great quantity of blood. It is necessary for the surgeon to remember the great size of this supra-scapu- lar artery, its long course over the shoulder, at what place it arises within the chest, and how it may be compressed. But in another sense also it is peculiarly important; for the supra- scapular artery makes inosculation with the lower scapular ar- tery, freer, and fuller than in almost any other part of any limb. One can h .rdly force tepid water through those small arteries wh?'h support the arm after the operation for aneu- rism; but the inosculations of this supra-scapular artery are so free, that often, though I have tied the arteries with great care, the very coarsest injection has gone round by it; and when I desired only to inject the head, I have found the arter- ies of the arm entirely filled. The conclusion which this leads to in wounds of the axillary artery is too obvious to need any further explanation. II. OF THE AXILLARY ARTERY. This artery assumes the name of axillary, where it lies in the arm-pit or axilla. The scaleni muscles being attached to the ribs, the artery passes first through betwixt the first and second scalenus ; next it passes out from under the arch of the clavicle, where it was protected ; then it falls over the breast in a very oblique direction ; it inclines outwards towards the axilla, lies flat upon the slanting convexity of the chest, is co- vered by the pectoral muscles, because the pectoral muscles arise from the clavicle, under which the artery passes ; but far from being protected, it is so far exposed as to be easily felt beating, and it is at this point only that it can be rightly com- pressed. It declines still outwards and downwards, till at last it gets so deep into the arm-pit, and so much under the scapula, 222 OF THE AXILLARY ARTERY. as to lie betwixt the serratus anticus and subscapular muscles; There it is rightly called the axillary artery. In this hollow it lies safe, protected by the deep borders of the pectoral muscle before, and of the latissimus dorsi behind, surrounded with fat and glands, inclosed within the meshes of the plexus, or great conjunction of nerves, which go to the arms, surrounded also by all the veins of the arm, which twine round it in a wonderful manner. Here it gives off the thoracic arteries to the thorax, and the scapular arteries to the shoulder. In short, the axilla itself is a complicated study ; but in all that respects the arteries it may be made very easy and plain. But let the surgeon remember that it is only by a perfect knowledge of the arteries, a bold stroke ofthe knife, and a masterly use of the needle, that the patient is to be saved from bleedings after wounds hereabouts ! for the old story of compressing the axillary artery above the clavicle is now of no credit with any surgeon of knowledge or good sense. As the artery turns over the borders of the chest, it gives one or two twigs to the adjacent parts, as to the scaleni, and to the great nerves which lie over the artery, and to the serrated muscle, where it lies under the scapula: but these branches are so small that it is unnecessary either to number or describe them. The thoracic or external mammary arteries are the first important branches ; they are four in number, and they are named after their place or office. 1. ARTERIA THORACICA SUPERIOR. The upper thoracic artery, being the first, lies of course deep in the axilla. It comes off about the place of the first or second rib ; it lies betwixt the lesser pectoral and the great serrated muscles ; it gives its chief branches to these muscles, and it also gives other branches to the intercostal muscles and the spaces betwixt the ribs. But, upon the whole, it lies very deep, is small, is so short that the next is entitled thoracica longior; it is an artery of little note. 2. ARTERIA THORACICA LONGIOR. The long thoracic artery is more important, supply- ing all the great pectoral muscles and the mamma. It was named the external mammary artery; but we are the more willing to change the name, since it has no likeness to the in- ternal mammary artery ; is in no respect a counter-part to it; OF THE AXILLARY ARTERY. 223 it might be named the pectoral artery. It is long, not tortu- ous, but straight and slender, and about the size of a crow- quill. It is needless to describe an artery so variable in its branches as this is ; it is sufficient to say, that after givinp- small twigs to the axillary glands, it terminates with all its lar- ger branches in the pectoral muscle, mamma, and skin, and in inosculations with the intercostals and internal mammary ; it is very long, descending sometimes so low as to give branch- es to the oblique muscles of the belly. 3. ARTERIA THORACICA HUMERARIA. The thoracic artery ofthe shoulder goes off from the upper and fore part of the axillary artery. Its place is exacdy opposite to that of the mammaria superior, viz. under the point of the coracoid process, insomuch that Haller has named it thoracica acromialis. It is a short, thick artery; it bursts through the interstice between the pectoral and deltoid mus- cles, and appears upon the shoulder almost as soon as it comes off from the main artery ; it resembles the thyroid in shape, being a short thick artery, terminating all at once in a lash of slender branches, which go over the shoulder in various di- rections : but I never could observe any order worth descri- bing. One deeper branch goes to the serratus major, a branch goes along the clavicle, gives it the nutritious artery, and then goes on to the pectoral muscle, and to the skin ofthe breast: it gives small branches to the axillary glands, and larger ones to the deltoid and pectoral muscles and skin of the shoulder, for this is very much a cutaneous artery. The chief branch is that which is last named, running down betwixt the deltoid and pectoral muscles : and the most curious branch is a small ar- tery which accompanies the cephalic vein, and runs back- wards along the course of the vein, a small and beautiful branch. 4. ARTERIA THORACICA ALARIS. Sometimes, though not always, there is a fourth thoracic artery. When it exists, we find it close by the last artery; its branches, which are sometimes numerous, belong entirely to the cup or hollow of the axilla ; it goes to the glands and fat, and thence its name of alaris or axillaris. This is the deepest or backmost of these mammary arteries ; it attaches itself to the lower border of the scapida, and we often see it 224 OF THE AXILLARY ARTERY. running along the lower border a considerable length, and gi ving branches chiefly to the subscapularis muscle. <&> These are the four mammary arteries which go to the breast. The arteries which go to the scapula follow next, and are only three in number ; one, which is the counterpart oi the supra-scapular artery, is the greatest branch from the axillary artery, supplies the lower surface ofthe scapula, and thence is named subscapular artery; one, which, as it is reflected round the joint by the outside, is named the external cir- cumflex artery : and one, which, as it turns round the in- ner side of the joint, is named the internal circumflex ARTERY. 5. ARTERIA SUB-SCAPULARIS. The subscapular artery is of a great size ; it is hardly described in books, I might say is hardly known to anatomists. Douglas, and most especially Sabbatier, have scarcely named it, though it is in fact one of the largest arteries in the body, being absolutely as large as the axillary artery, from which it takes its rise.* The greatest mass of flesh in almost any part of the body is that which lies under and around the scapula in a strong man ; and this artery supplies almost all that mass. It goes off from the axillary7 opposite to the neck of the scapula, just under the long head of the biceps brachii: it no sooner comes off from the axillary artery, than it attaches itself to the lower border of the scapula ; and as soon as it comes to the edge of the sca- pula (but sometimes lower clown the edge, viz. where the head of the,biceps comes off) it splits into two great branches ; one of which goes to the upper, and one to the lower surface. But to describe each little artery among such a mass of flesh, or to expect to find diem regular, would be yen thoughtless ; the general course of them only can be described. First, The greater branch which goes to the lower surface of the scapula, * It is named often scapularis inferior or infra-scapularis; it is better named subscapular, both to harmonize with the name subscapular muscle, to which it be- longs ; and also to contrast with its counterpart, the supra-scapular artery, which comes from the subclavian arterv. OF THE AXILLARY ARTERY. 225 is the proper trunk ofthe subscapular artery ; it divides into two great branches, which course all over the lower or hollow surface of the scapula: one of these is deeper, runs downwards along the naked border of the scapula, lies under the muscles upon the flat bone, and supplies the inner surface of the sub- scapular muscle with many branches. It sends a branch up- wards, which runs along the inner surface of the neck ofthe scapula, runs still forwards under the root of the coracoid pro- cess, and its extreme branch goes round by the basis of the scapula to make an inosculation with the larger branch. Secondly, The larger branch keeps nearer the surface, and supplies all the outer side of the subscapular muscle. Its ge- neral course is round the scapula, down the fore edge, then round by the lower angle, then up by the line ofthe basis sca- pulae, encircling it with what might be named a coronary ar- tery. It first gives branches to the teres major; then passes down along that muscle to the angle of the scapula ; then tur- ning along the angle of the scapula (which it does not do with- out leaving many branches behind,) it runs in a waving line all round the basis scapulae, till it arrives at the upper corner, where it ends in free inosculations, both with its own deeper branch, and also with the supra-scapular artery which comes along the shoulder. Now this great branch, with all its arteries, belongs entire- ly to the lower surface of the scapula ; but the branch which leaves it at the neck of the scapula turns round under its lower edge, gets to the upper surface of the scapula, runs in under the infra-spinatus and teres major muscles, betwixt them and the bone; and although the supra-scapular artery from the shoulder supplies chiefly the upper part ofthe scapula, yet it is chiefly above the spine that that arte'ry circulates, while the lower parts ofthe infra-spinatus and the teres minor muscles are left to be supplied by this reflected branch of the subscapu- lar artery : thus this reflected branch gives its arteries, first to the teres, then it enters into the hollow under the spine, and besides supplying the infra-spinatus and the bone itself, it aLo makes a circle, though a shorter one, and inosculates with the supra-scapularis, just as the other branch of this same artery does on> its lower surface. This branch descends nearly to the corner of the scapula before it begins this inosculating cir- cle ; but it sends also another chief branch round the neck of the scapula, which advancing towards the supra-scapular notch, inosculates veiy largely with the supra-scapular artery. Thus is the scapula encircled, and supplied with a wonder- ful profusion of blood by two great arteries ; one, the suprA- scapui ar artery, coming across the neck, over the shoulder, Vol. II. 2 F 226 OF THE AXILLARY ARTERt. and through the scapular notch; another, the subscapular artery, which comes from the axilla to the lower flat surface ofthe scapula, and divides at the edge ofthe scapula into two great branches ; one of which keeps still to the flat surface, while the other turns over the edge ofthe scapula, and supplies in part its upper or outer surface. 6. ARTERIA CIRCUMFLEXA POSTERIOR. The posterior circumflex artery is a very large one. It arises either along with, or immediately after, the great subscapular artery ; the place of it is of course settled by the place of the shoulder-joint, for it belongs so peculiarly to it that it is sometimes named the Humeralis, sometimes the Ar- ticularis, sometimes the Reflexa Humeri. It goes off between the subscapularis and teres major muscles ; it passes in be- tween them to get to the joint ; it then turns round the shoul- der-bone, accompanied by the circumflex nerves, just as the supra-scapular artery is accompanied by the supra-scapular nerve ; it ends, after having made nearly a perfect circle, up- on the inner surface ofthe deltoid muscle. Its branches are, first, Twigs to the nerve which accompa- nies it, and to the capsule of the shoulder-joint.—Secondly, Branches to the coraco-brachialis and short head of the biceps, and to the triceps, and a twig to that groove in which the ten- don of the long head of the biceps lies.—Thirdly, It sends large branches to the subscapularis, to the long head of the tri- ceps, &C.—And, lastly, The artery, far from being exhausted by these branches, goes round the bone, turns over the joint under the deltoid muscle, and ends in a great number of bran- ches, still accompanied by branches of the nerve, which are distributed in part to the capsule, but chiefly to the lower sur- face ofthe deltoid muscle, where it lies upon the joint. 7. ARTERIA CIRCUMFLEXA ANTERIOR. The anterior circumflex artery, which goes round the fore part of the joint, bears no kind of proportion to that great artery which passes round the back. The anterior goes off from the same point nearly with the posterior, or sometimes arises from the posterior itself; it takes a direction exactly opposite ; it keeps close to the shoulder-bone, passes under the heads of the coraco-brachialis and biceps ; encircles the head ofthe os humeri just at the root ofthe capsular ligament, and OF THE AXILLARY ARTERY. 22 7 goes round till it meets and inosculates with the posterior cir- cumflex artery7. I never could find those muscular branches which are said to go to the scapula, or have found them very trivial ; the whole artery belongs to the bone and its parts ; it encircles the root of the capsule with a sort of coronary arte- ry ; it gives twigs to the capsule, the periosteum and the ten- dons, which are implanted into the head of the bone ; and ha- ving given twigs to the heads of the biceps and coraco-bra- chialis, it gives off its only remarkable branch, which is indeed regular and curious ; it is a small branch which runs down along the bone in the groove in which the tendon ofthe biceps lies. Concerning the axillary artery in general, there is more to be observed than this occasion will allow. But these things must not be passed over in total silence. In the first place, the artery, as it passes over the border of the chest, and after lea- ving the arch ofthe clavicle, is felt beating, and there only can it be compressed. The compressing of the subclavian artery7 with a tourniquet or with the thumb, attracted at one time so much attention, and incited so many to speak about it, that it came to be thought important, and has been ever since esteemed practicable ; and yet even those who have spoken the most confidently have ta- ken the thing merely upon vague report, have neglected to read the proper books, have described the way of compress- ing as above the clavicle, not knowing that it should be done below it. Camper, in his " Fabrica Brachii Humani," first jnentioned what he had demonstrated in his class, viz. that it could, by placing the thumb under the point of the coracoid process, so compress the axillary artery against the second rib where it lies upon it, that even the strength of a syringe could not push an injection through it.* And those who learn * In cadaveribus plus semel in publico theatro monstravi, comprimi posse in- tegrant arteriam ; ligabam arteriam aortam infra arcum, resccabam deinde axil- larem dextram, ac siphone axillarii sinistra: adaptata fortiter aquam impellens, solo digito eo modo moderare potui subclavian!, ut ne gutta quidem efflueret : quod quanti momenti esse queat in amputatione humeri in artieulo nemo non videt. In vulneribus sclopetariis, aliisque circa humeri articulum inflictis, sanguinis pro- fusionem similiter compescere, si non penitus sistere possemus. Vid. Camper, lib. j p I5.__The plain reason why we are able thus to compress the artery in the dead subject is the want of resistance in all the muscles. If ever it be possible in the living body, it must be when the strength is low, and the circulation very languid, after the patient has fainted wirh loss of blood. 228 OF THE AXILLARY ARTERY. things by hearsay, have said that " the subclavian artery could be compressed by thrusting the thumb in above the clavicle ;" although, in fact, the arch is so deep, the muscles so strong, and the artery so little exposed, that this is absolutely impos- sible. From my speaking with a seeming interest about the prefe- rence of one of these two places to the other, it may be thought that I believe this piece of knowledge useful: quite the re- verse ! I know it to be dangerous ; I know it to be less practi- cable than authors report and believe ; and I repeat what I said on a former occasion, that " it is easy to stop the pulse of an artery, but quite another matter to stop the flow of blood through it." We thrust down our hands and compresses, and rest with our whole weight upon the artery ; it seems stopped, because the pulse is stopped ; but the first stroke of the knife shows us how far we are gone in a dangerous mistake. I may say, without breach of confidence, that I have seen one gen- tleman trust to it, who will never trouble himself about it again. He was a dexterous surgeon ; and in a great aneu- rism of the axilla was deluged with blood at the first stroke of the knife, and saved his patient only by a plunge of the great needle. Secondly, It is much to be lamented that we cannot really suppress the blood ; not merely because it would make every wound less dangerous, but because it would greatly facilitate operations which we are called upon every day to perform.— Would it not be pleasant if we could cut the cancerous breast without the loss of blood ? or search into the axilla with per- fect deliberation, and cut diseased parts out with the knife, not tearing them in a brutal manner with our fingers ? Yet still, by studying this piece of anatomy, the surgeon knows both from what source all the arteries which bleed upon the surface of the amputated breast come, viz. the long mammary- artery ; and also that in any very dangerous situation it would be easy to command all the bleeding orifices by one dip of the needle, the axilla being open. He also knows that the thora- cica alaris and the shor. thoracic artery supply all the glands, and that these lurk too deep in the axilla to be secured other- wise than by a compress : so that these arteries are in fact opened by tearing with the fingers, and are stopped by thrus- ting in a spunge. He knows also how many large arteries there are, especially about the scapula, of which the bleeding must resemble that of the axillary artery itself ; he will judge of the nature of the wound by the pulse ; and he will act with great advantage in all doubtful cases by remembering these great arteries of the scapula, which either bleed outwardly OF THE AXILLARY ARTERY. 229 most furiously, or if they seem to stop, it is only by filling the axilla with blood. Thirdly, The connection of the artery with the axillary nerves, though it must be more fully described in another place, must yet be observed here as a relation too important to be omitted. The artery passes along with the nerves through the interstice of the scaleni muscles ; the nerves, which con- sist of no less than seven pairs, make by their mutual connec- tions a sort of net, which is called the plexus of the axillary nerves. This plexus has its meshes formed, not by small di- visions, but chiefly by the seven great cords. This broad plex- us lies over the artery as it comes out from the chest; the ar- tery perforates the plexus, or passes through one ofthe largest meshes in the cavity of the axilla ; and when we extend the arm, for .example, to cut out an axillary7 gland, the great veins lie nearest the knife, or lowest in the axilla ; the plexus of nerves next; and last of all the artery which has just perfora- ed the plexus of these great nervous cords ; three nerves are below the artery and two above; and when the arm is luxated, and the shoulder-bone pushed downwards, the head of it is so pressed against the net of nerves, and the artery is so com- pressed betwixt the head of the bone and the mesh of nerves, that I have very7 seldom failed to find the pulse almost entirely- suppressed in luxations of this kind. This connection, viz. with the nerves, is a very interesting one. It is plainly such that the artery cannot be hurt without a wound ofthe nerves ; it has never been known that the arte- ry has been cut in the axilla without the arm being lamed by this wound of the nerves : also the nerves cannot be hurt with- out the artery being in danger ; but it does escape sometimes ; of which, among other examples, this is one of the most singu- lar.—I have seen the artery escape in wounds when the nerves were hurt ; but how it could escape the stroke of a blockhead's needle in the following case, I am at a loss to conceive. A Woman came to me with a great string hanging in her axilla. and along with her came her surgeon. He had about three months before cut off her breast for a cancer, and moreover some glands from the axilla, from which there was a bleeding; and of course, as his fingers could not go deep enough, he took a needle proportionably large, struck it down into the arm- pit, and tied all up. ' When he brought his patient to me, there hung from the arm-pit, not a surgical ligature, but a good large tape ; the axilla was a large gaping and terribly fetid ul- cer ; I passed my finger into it, and felt the arteries beating around it, and the tape firm about some cord of nerves, whether one or more I could not tell; the Woman's fingers were as 230 OF THE BRACHIAL ARTERY. crooked as a bird's talon, and her arm hung by her side quite useless and lame. I made the surgeon feel the nerve with his finger, and offered to cut out the ligature safely; but he carried away his patient, that he might, though at a long interval, finish the operation himself. The breast had been long healed, and the cord acted as an issue in the axilla. How near the edges of this needle must have been to the great artery, it is terrible to think ; and it is most providential that such accidents do not happen daily, considering how much this crooked needle is used in deep places, where it is least fit to be used. III. OF THE BRACHIAL ARTERY. The brachial artery is that division of the artery which is marked by the tendon of the great pectoral muscle ; for as that is the fore border of the axilla, all above that is axillary, and all below it brachial artery, down to the bend of the arm, Where it divides into the radial and ulnar arteries. The bra- chial artery runs close along the os humeri on its inner side, here the bone is most naked ; and this is the line in which we feel the artery beating, and apply the cushion of the tourniquet. To describe, as some authors have done, each insignificant and nameless branch which this artery gives off, were to make a simple matter intricate beyond all enduring. The whole matter is this : As the artery goes downwards, lying exactly on the inner side of the arm bone, and directly in the middle betwixt the biceps on the fore part and the triceps behind, it gives frequent branches to each. Those going to the biceps are short, small, pretty regular, and exceedingly like each other all the way down the arm ; and they are thus frequent, and very short, in consequence of the artery adhering closer to the sides of the biceps. Not one of them can be distin- guished, or is worth naming. Those which it sends down- wards to the triceps are (in consequence of that being a large muscle, with several thick and fleshy origins) both longer and more tortuous, and more important; and they accordingly have some of them appropriated names. Of these arteries going down towards the back part of the arm, and working their way among the muscles, three chiefly are to be observed. First, the arteria profunda superior, which goes round the back of the arm to the exterior muscles, and is often named the upper muscular artery. Secondly, another like it, called arteria profunda inferior, or the lower muscular artery.— Thirdly, the ramus anastomoticus major, which anastomose? OF THE BRACHIAL ARTERY. 231 round the elbow with the branches of the ulnar artery. These three chiefly deserve notice. 1. ARTERIA PROFUNDA HUMERI SUPERIOR. Those arteries, which in the limbs go deep among the fleshy- parts, as in the arm or thigh, have always one of two names, either profunda or muscularis, and often both. The upper deep muscular artery of the arm is about the size of a crow- quill, or larger ; it goes off from the inner side ofthe brachial artery, just where the tendons of the latissimus dorsi and teres are inserted, and very often it arises from the great artery of the scapula, or that of the joint, viz. the sub-scapularis, or reflexa humeri. The profunda turns downwards and backwards round the bone ; it glides in betwixt the first and second head of the triceps ; there it divides within the thick flesh of that muscle into two chief branches, or the two branches sometimes part immediately after their common origin, or sometimes they go off apart from the humeral artery. One of these, perforating the biceps muscle, turns quite round the bone; and Monro the Father, who gave us the name of spiral nerve, named this also, very properly, the muscular spiral artery : so this artery also, as well as the supra-scapular and circumflex arteries, has its accompanying nerve. This long artery runs down the back and outside of the arm ; it descends quite to the outer condyle of the os humeri, and by branches round the olecranon, and over the outer condyle, it inosculates very freely with the radial artery. The other branch of the profunda superior runs down the inner side of the arm, gives many branches to the triceps, and coraco-brachialis ; gives a few also to the biceps and deltoid muscle : its longest branch, the proper termination of the ar- tery, runs downwards till it touches the inner condyle, as the- posterior branch does the outer condyle ; and this inner artery communicates with the outer branch round the olecranon, making small but frequent and beautiful inosculations ; and it also inosculates over the condyle with the reflected branch of the ulnar artery. In short, the profunda superior turns down towards the back part of the arm, buries itself under the tri- ceps muscle, supplies all the flesh of the triceps, and divides in the heart of that muscle into two branches, both of which go down to the elbow-joint, and inosculate ; the one, round the outer condyle with the radial artery; the other, round the inner condyle with the ulnar artery. 232 OF THE BRACHIAL ARTERY. 2. ARTERIA PROFUNDA HUMERI INFERIOR VEL MINOR. The lesser profunda, or the lower muscular artery, is so named because it resembles the former in almost all points. It is smaller, being not half the size (viz. of a crow-quill), and goes off, in general, about two inches lower down the arm. Its course, also, is exactly similar, except in this, that it is single, does not divide into two branches; it gives twigs to the muscles of the arm ; runs down to the inner condyle, and after touching it, makes a sudden and serpentine turn, by which it gets upon the back part of the elbow-joint. Its chief inosculations are with the upper profunda, and with the recur- rens interossea upon the back part of the joint. Betwixt the upper and lower profunda there generally is sent off that artery which is to nourish the bone. It is named arteria nutritia humeri ; but is not of sufficient import- ance to be numbered among the main branches of the artery. The nutritious artery sends off small branches, or rather small twigs, to the brachialis, or that muscle which lies under the biceps and to the triceps ; and it perforates the bone about its middle in one larger artery, and sometimes there are also one or two smaller ones. 3. RAMUS ANASTOMOTICUS MAJOR. The greater anastomosing artery is one of three or four which anastomose round the elbow-joint: for as the hu- meral artery advances towards the bend of the arm, it begins about three inches above it, to give off sidewise, and almost at right angles with the trunk, three or four small arteries, more or fewer, according to the size of the arm. Each of these sends its little twigs round the condyle, to inosculate with the arteries of the fore-arm both radial and ulnar. Among these one is distinguished for its size and importance ; it is one of the largest of these arteries, and thence named anastomoti- cus magnus ; it arises from the Humeral artery about three inches above the joint; it lies close by the side ofthe brachialis internus, and gives many branches to it and to the triceps ; but it is chiefly expended in three branches, one of which turns backwards, and running up the arm gives branches to the mus- cles, and inosculates with the profunda : another goes down- wards towards the middle of the bend of the arm, and gives branches to the pronator teres and the flexor digitorum ; ancl then going deeper, it touches the capsule, and makes a beauti- OF THE BRACHIAL ARTERY. 238 ful inosculation over the forepart of the joint with the radial recurrent or inosculating artery: another branch, the most important, and the chief termination of the artery, runs down betwixt the olecranon and the condyle, in the hollow where the ulnar nerve lies. It first contributes to that net-work of inos- culations which covers the back of the joint over the olecra- non ; it inosculates very freely with the recurrens ulnaris ; and it is this inosculation, that gives the artery its importance and its name. This is the channel through which the blood goes after the operation for the aneurism, as we know from prepara- tions ; and I have several times felt for it, and found it after the operation, while the arm was still very small, having been wasted by the disease and by the suppuration. I have not, in describing these arteries of the arm, once mentioned the name of collateral artery ; for it is a name which must be entirely dropped, because it has been much abused. Sabbatier, Murray, Haller, and all the French and German anatomists, have named the arterise profundae col- lateral arteries ; because they lie alongside of the great artery, running along with it down the arm. Douglas, and the English anatomists and surgeons, have called the three or four short anastomosing branches near the elbow the collateral arteries ; because, though they run off at right angles or ob- liquely from the trunk, yet they run parallel with each other. Dropping this name, then, we find no more than three arteries in the arm of any note : the upper or greater profunda, with its own branches ; the lower or lesser profunda; and the great anastomosing artery. OF THE ARTERIES OF THE FORE-ARM, VIZ. OF THE RADIAL, ULNAR, AND INTEROSSEOUS ARTERY. The place and condition of this artery at the bend of the arm is as interesting as where it lies in the axilla ; for while bleeding is allowed, or is practised by low and ignorant people, operations at this point must be more frequent than at any other, and must be easy or successful only in proportion as the artery and all its relations are well understood. The humeral artery still continues an undivided trunk, much lower than the bend of the arm ; though we are accus- tomed to name that as the place at which it divides. The whole arm, it must be remembered, is covered with a fascia, Vol. II. 2 G 234 OF THE ARTERIES and that fascia lies over the artery; but at the bend of the arm there is a peculiar fascia, or at least the round tendon of the biceps so strengthens the general fascia, by sending a broad ex- pansion obliquely across the bend of the arm (which fascia is fixed into the condyle and down the edge of the ulna), that we call this expansion peculiarly the tendon of the biceps, and say that the artery is at the bend of the arm covered and protected by the tendon of the biceps muscle. The condition then of the artery is shortly this : it comes from the inside of the arm, inclining all along towards the middle of the bend or folding of the fore-arm; there, without any particular ring or aperture for its admission, it passes under the aponeurosis of the biceps muscle -r for the aponeurosis of the biceps and of the arm in general are one continued sheath. When thus lodged, behind the tendon, it lies in a deep hollow betwixt the flexors and ex- tensors of the arm, or, in other words, betwixt the muscles of the upper and of the lower edge ; the tendon of the biceps covers this triangular hollow; the floor or bottom of it is the coronary process of the ulna and the forepart of the elbow- joint, and there the artery lies imbedded in cellular substance, encircled by those veins which accompany the artery particu- larly, and which are thence named venae comites ; and it car- ries along with it a nerve in diameter equal to itself, and this nerve is named the great radial nerve. The artery does not divide immediately even after it has thus passed the bend of the arm, but goes down deep among the flesh of the fore-arm, and there divides ; the ulnar artery being lodged under the thick flesh of the pronator and flexor sublimis muscles, and the radial artery under the strong fleshy belly ofthe flexor radialis and ofthe supinators, not absolutely within their substance, but under cover of their fleshy bellies, which swell out into a great thickness at this part of the arm. The only part of the artery which is exposed, the point which we feel beating is that where the single and undivided trunk first begins to pass under the thicker fascia of the biceps mus- cle ; and there the artery is pushed forwards, raised, and made to appear superficial by the projection of the coronoid process and brachialis muscle, or, properly speaking, by the protrusion of the forepart of the elbow-joint. This is just before it sinks into the triangular hollow betwixt the muscles. This artery is singular in one kind of lusus naturae, which never happens, nor any thing similar to it, in the lower ex- tremity, viz. that the trunk of the artery forks into two great branches high in the arm ; sometimes in the axilla, but oftener in the middle of the arm, or opposite to the pectoral muscle : and I have constantly observed, when this happened, that the OF THE FORE-ARM. 225 radial artery was, as it were, the accidental branch, and passed across the arm near the bend ofthe elbow, so as to traverse the ulnar or main artery ; and that the radial artery passes quite on the outside of the fascia, which binds down the ulnar or main branch of the artery. This short description involves many points which the sur- geon should think of, and more than can be touched upon in this place. The following consequences certainly follow from this arrangement of parts. Fi t, The artery lying thus deep under the biceps, cannot be hurt by any skilful surgeon, though bleeding the very vein under which it beats, and at the most critical point; it is hurt, as far as I have observed, only by the rudest stroke of very ignorant fellows ; I have seen in six cases a wound in it litde less than a quarter of an inch in length. In one of the opera- tions I found it absolutely transfixed ; the blood had been poured out from the orifice behind ; I felt with surprise the artery running over the tumour, not under it; and having opened the sac, I passed a probe through the artery from side to side. Secondly, Since the artery divides only after it has gone deep, where its great branches are protected by the muscles of the fore-arm, the trunk only is wounded in bleeding; the branch is never wounded ; and we cannot but be surprised that Hun- ter, Haller, Sharp, and others, who ought to have studied this point, believed it to be sometimes at least wounded in one of its branches ; nor can we think, without surprise, of the arteries being so little understood in the time of Dr. Monro the Father, that he is forced to argue the propriety of doing the operation of aneurism from this fact, " That though it were dangerous to trust to the common anastomosis round the elbow, yet it sometimes happens, that the two branches of the radial and ulnar are set off in the axilla." This surely must have been but a cold assurance to the surgeon in those days, viz. that he was to trust chiefly to the chance of a lusus naturae for the success of one of his greatest operations. Thirdly, It must follow, since the artery lies behind the fas- cia, and is wounded through it, that the blood being poured out behind the fascia, must raise it into a hard, firm, and (in time) inelastic tumour, growing every day firmer and harder. If surgeons will but think of this, they will go through their operation more correctly. It makes a point of vast importance in the description of aneurism, since it gives outwardly the true character, and inwardly the true shape and appearance of the tumour, when the operation is begun, the outward incision being performed. Had it been but attended to rightly, what 2o6 OF THE ARTERIES noise and wrangling might it not have saved about the nature and names ofthe disease (yet still the older surgeons knew and described this piece of anatomy, though they made but a poor use of it ?) and what idle and stupid descriptions might it not have prevented, such as we have never seen in surgical books till now, of diffused aneurism, and the operation for diffused aneurism ; when in truth the first stroke of the knife shows it to be a tumour very different from that which such names, and such formal divisions, and old-fashioned descriptions must con- vey ? The cup of an aneurism is the triangular hollow which I have described, and the bag of the tumour is the extended fascia. Fourthly, The course of this double artery tempts me to be- lieve, that in those few cases where the blood of an aneurism was truly diffused, where it was an ecchymosis, where the blood was not confined by the fascia, but poured out under the skin, and driven upwards to the shoulder, and downwards to the fingers, giving the whole arm the appearance of mortifica- tion ; that in such rare cases, there must have been a high di- vision, and that the preternatural artery had been wounded, for it lies above the fascia, it is lodged in no hollow, such as might receive its blood, nor covered by any membrane which might confine it; but at all events, I am persuaded that Hun- ter is wrong in suspecting that, since the pulse so seldom re- turns instantly, this preternatural artery and the true one must be often tied together: for if the preternatural artery were wounded, it would be a very diffused aneurism, under the skin and above the fascia ; but the main artery would be found in its place, under the fascia, quite safe ; whereas, if the true artery were wounded, the tumour would be under the true fas- cia, the preternatural artery would cross by the side ofthe tu- mour, or over it, and the wounded artery being at the bottom of its own tumour, the two arteries would be six inches apart. Besides, the necessity of supposing this is not so strong as Hunter believed; I have seen the pulse return during the dressing of the arm, when the dissection was so wide and free tuit I am sure there could be no lusus naturae, but one artery di v. ng in the common place. I ft, ly, The close connection of the artery with the great radial nerve must always be considered in all wounds at the bend of the arm ; and especially it constitutes a difficulty in the operation of aneurism, of which authors of great eminence have spoken far too lightly ; and surgeons of character have tied it in with their great ligatures, as if for amusement, or that they might see what would ensue. But, as I have said on another occasion, " a man must show me either some positive OF THE FORE-ARM. 23f necessity for doing this, or some positive good consequences Which will result from it, before I admit him to argue about the bad effects which may ensue." Will any man persuade me, after the case which I have just related, that it is good or harmless to tie in the largest nerve of the arm ? We see by that case, that the ligature's remaining firm in its place for three months is one of the least of the ill consequences, and the others may easily be conceived. Of these ill consequences I have seen more than I will venture to tell. The humeral artery having left this most critical point at the bending of the arm, divides into three great branches, the radial, ulnar, and interosseous arteries ; at least the ulnar gives off the interosseous so soon, and the interosseous is so large, and has so pointed a destination, that I take the privilege of describing the three branches apart. The ulnar artery, which we must regard as the continuation ofthe main artery, makes its way through the thickest flesh ofthe fore-arm, goes along the ulnar edge of the arm, appears again from under the flesh, about three or four inches above the wrist; it goes down to the root of the little finger, and gives the chief arches in the palm ofthe hand, and all the arteries ofthe fingers, saving on- ly the inner side ofthe fore finger. The radid artery goes off like a branch from the ulnar, or, in other words, the ulnar seems to continue in the course of the main artery, while the radial goes off to one side ; it makes its appearance as a super- ficial artery much higher in the fore-arm than the ulnar does ; its chief branch turns backwards over the wrist, or root of the thumb, and it gives all the arteries of the thumb and fore fin- ger, as the ulnar does ofthe other fingers. The interosseous, again, is truly a branch from the ulnar ; it comes off where the ulnar lies deepest; it runs along the interosseous mem- brane, whence its name ; it belongs to the deep muscles of ithe arm ; it scarcely passes the wrist, or at least mounts buv'>i *ery little way along the back of the hand. These are the greatest divisions of the artery ; but before entering upon these, it will be well to set apart and describe one particular set of arteries, viz. the recurrents ; both because they belong in a peculiar manner to the joint, and because the recurrents, from whichsoever of the great arteries they come, still serve the same office, viz. of inosculating with these from the above joint; though, after all, this part of their office at- 238 OF THE ARTERIES tracts our attention, chiefly because we depend upon these in- osculations for our success in operations for aneurism, though unquestionably the chief use of these arteries is to supply the joint and adjacent parts ; and their inosculations are but a se- condary office. arteria recurrentes. The recurrent arteries are small arteries corresponding with the anastomosing arteries from above. They turn quickly backwards almost as soon as they are clear of the main arte- ries from which they arise : they encircle the whole joint, for they are no less than four, or sometimes five, in number ; one from the radial, two from the ulnar, and one from the interos- seous artery. RECURRENS RADIALIS ANTERIOR. The anterior recurrent of the radial artery is the first branch which it sends off, excepting a small branch to the su- pinator and skin. The place where the radial recurrent is to be found, is deep in the hollow betwixt the brachialis internus or muscle of the arm, and the extensor radialis or first muscle of the fore-arm, viz. that which constitutes its outer edge.— The recurrent lies upon the fore part of the joint, where the outer condyle is : the muscles which lie over this recurrent ar- tery, or near it, are the two flexors of this wrist, the supinator longus, and the biceps, and these receive its first branches ; and one of its branches runs down along the tendon of the supina- tor. Its next branches go less regularly to the other muscles of the fore-arm, as to the pronator teres, and to the flexors of the fingers: it has one superficial anastomosing artery, whose anastomoses are not upon the naked joint; but, on the contrary, the branch mounts along the fore part of the brachi- alis internus muscle, and inosculates under the biceps w7ith the lesser or lower profunda. A second anastomosing branch goes deeper; it passes through the flesh or belly of the brachi- alis, and anastomoses with the ramus anastomoticus major from above. A third anastomosing branch is the chief branch; it lies deeper still upon the forepart of the joint, in the hollow which I have lately mentioned : it runs up under the belly of the supinator, along the fore part of the shoulder-bone, where it inosculates with the upper profunda humeri, and chiefly with its greater branch called spiral artery ; which turns round the bone, and ends here over the outer condyle. OF THE FORE-ARM. 239 This is the recurrens anterior of the radial artery ; but none of these branches have I ever seen or felt to be enlarged after operations for aneurism. The success of that operation de- pends entirely upon the arteries next to be described, viz. the ulnar recurrents, which are always two in number ; but some- times these two recurrents go off in one branch from the ulnar: in which case, viz. of a single recurrent coming off from the ulnar, it divides immediately into two branches, and the one takes the fore and the other the back part of the joint. RECURRENS ULNARIS ANTERIOR. The anterior recurrent ofthe ulnar artery goes off the first of the branches, immediately before it gives off the inter- osseous, and where the artery lies deep in its triangular hol- low. This anterior artery passes up under cover of the pro- nator teres, lies close upon the fore part of the inner condyle, and is of importance, not only by its own size, but also by its anastomosing with the ramus anastomoticus major, which is the largest of the arteries from above. RECURRENS ULNARIS POSTERIOR. The posterior recurrent of the ulnar artery is often a branch of the anterior one, coming off with it in one common trunk. When it comes off apart, it arises a little lower ; it is a larger and stronger artery, i. e. it makes as full inosculations, goes farther, and gives more branches to the muscles. This posterior recurrent arises from the ulnar at that place where it perforates the bellies ofthe flexor muscles; it also dives through betwixt the two bellies of the flexor muscles of the fingers, it thus gets round the condyle, for these two muscles arise to- gether, from the condyle: the artery gives many branches both to the pronator and flexor muscles, and to the periosteum, and capsule of the joint; it then lodges itself in the deep hol- low which is betwixt the olecranum and the condyle, where the ulnar nerve lies (that nerve which we feel so benumbed when we strike the inner side of the elbow.) The artery stretching upwards along the bone, meets a similar descending branch from the upper profunda, and inosculates with it. As far as we yet know, the whole weight of the business in saving the arm after aneurisms depends upon these two arteries. In Mr. White's preparation it is the anterior branch which is en- larged, inosculating with the anastomoticus major over the 240 0F THE ARTERIES fore part ofthe inner condyle. In a preparation which I have, it is the posterior artery which runs tortuous and enlarged be- hind the inner condyle : but I must add to the authenticity of this preparation, by noticing, that I have several times felt distinctly, after successful operations for the aneurism, that it was this posterior artery that was enlarged. RECURRENS INTEROSSEA. The recurrent ofthe interosseous artery is the first of its branches, though sometimes this recurrent rises from the ulnar a little above the interosseous. This artery going to the middle and back part of the joint is very constant; it first sends one smaller branch forwards towards the root of the brachialis internus muscle, which inosculates over the fore part of the joint with the ramus anastomoticus magnus, and with the ul- nar and radial recurrents ; but these inosculations and this an- terior branch are of small importance. The chief branch goes through that lacerated-like hole which is in the upper end of the interosseous ligament; and the artery having passed through this hole, and got to the back of the joint, it runs for two inches upwards along the back of the olecranon, contribut- ing greatly to form, by its inosculations with both branches of the profunda superior, that net-work of arteries which covers all the back part of the joint, and which belongs chiefly to the joint, to the capsule, and to the bones which form the joint. From these anastomosing branches which belong to all the three arteries, we now return to describe the general course of the three great arteries ; and first of the radial. ARTERIA RADIALIS. The radial artery is properly the first branch of the ul- nar ; it goes off from it at a pretty obtuse angle in the bend of the arm : it passes under the pronator muscle, emerges from under it above the middle of the arm, follows the long tendon of the supinator, and runs under it down to the root of the thumb ; it is at the root of the thumb only that it divides into its great branches : and a clear proof that in its course down the fore-arm it gives off none but small and irregular muscular branches, is this, that it preserves almost an equal diameter in all its progress from the elbow to the wrist. This is the artery which lies naked upon the radius at the wrist, where we feel the ptdse. It lies more superficial, less OF THE FORE-ARM. 241 imbedded in muscles, than the ulnar artery ; for six inches above the wrist there is to be felt nothing but the naked artery7 the sharp tendon of the supinator, and the bone. The radial artery, as to its course down towards the wrist, is direct; but with regard to itself, it is tortuous, with short and gende wavmgs. Of its branches, as it moves down the fore-arm, there is not one that is worthy to be named. First it gives a branch to the supinator, and to the extensors of the carpus; then it gives the radial recurrent, already described ; then having gone a little deeper among the muscles, it repeats its branches to the supinator and extensors ; but being deep, it gives also twigs to the pronator and to the flexor radialis, in- osculating with the interosseous arteries. Next the radial ar- tery, emerging from among the thickest of the muscles of the fore-arm, becomes superficial, touches the naked radius, and runs along it, with the belly of the flexor pollicis below it and the long tendon of the supinator above it. Here are no mus- cles lying on the outside of it, nothing but the tendon ; and therefore all its twigs are downwards to the flexor pollicis, upon which it lies ; the flexor digitorum, which lies next to that; and to the flexor radialis and the palmaris longus. Next it gives deeper branches, viz. to the pronator quadratus ; and also it gives small twigs, which accompany the several tendons along the naked bone. Arrived at the wrist, it does not divide, as authors have represented, into two branches, viz. a palmar and a dorsal artery, but quite the reverse ; the radial artery passes on undivided to the root of the thumb, and there divides into three great branches ; one to the thumb, one to the fore-finger, and one to the palm of the hand: it does in- deed, while it is passing the wrist, give two considerable branches, one to the palm, and one to the back of the hand; yet they are but branches. ARTERIA SUPERFICIALIS VOLvE. The first branch, then, of the radial artery, after arriving at the wrist, is that which goes across the palm of the hand, and may be named the superficial artery of the palm. It goes off just where the main artery is about to turn over to the back of the hand ; it passes in general through the flesh of the thumb, going under the root of abductor brevis pollicis. This artery- we generally find dividing into three branches : the first is a more superficial branch, which crosses the palm of the hand, and gives its twigs to the skin, palm;ir aponeuro- sis, annular ligament, and all the tendinous parts about the Vol. II. 2 H 242 OF THE ARTERIES joint: the second is a larger and more important branch ; it is the middle branch of these three ; it goes deep ; and having given several branches to the muscles about the root of the thumb, and to one or two of the interossei muscles, it makes a large inosculation with the great palmar arch, which seems to be indeed the chief tendency of the whole artery : the third branch is less regular than the others ; it mounts along the root of the thumb, and belongs to its outer edge*. The next branches of the radial artery are very small and nameless twigs, which go to the naked part of the wrist, to the tendons, ligaments, and the bones ; and then comes the artery opposite to this artery of the palm, viz. the artery of the back of the hand. ARTERIA DORSALIS CARPI. The artery of the back of the hand comes off from the radial, just after it has turned over the root of the thumb. It takes its course directly across the back of the hand, over the carpal bones; and by its frequent inosculations w7ith branches from the ulnar artery, and with the interosseous ar- teries, it makes beautiful net-works across all the naked part of the back of the hand. After this beautiful net-work, it sends twigs forwards, which lie close upon the bones, go to the mus- cles which lie betwixt the bones. The muscles are named in- terossei, and these twigs are named after them. The first interosseous artery is large, long, goes up in a direct course to the fork betwixt the fore and mid fingers, and plunges into the cleft of the digital artery at right angles with it. The dorsalis manus gives then a second twig like this, and then a third ; named the first, second, and third interosse- ous arteries : but they are all smaller than the first, and all the three communicate with the arteries from the palm. Before the final division of the radial arteiyf into its three branches, it gives a third artery, or, as often happens, two arteries, to the back of the thumb. * This branch anatomists have thought fit to call arteria ulnaria ra- dialis pol n cis, which involves such a complication of contradictions, that, upon reading it, one would naturally turn to the tables of errata. The artery is called radialis, because it comes from the radial artery; and ulnaris pollicis, because it goes upon the ulnar side ofthe thumb. f Notwithstanding the inconsistency of retaining the name of radial artery, after thc artery has passed the wrist, and begun to run along the thumb, I venture to sacrifice verbal accuracy, and would make much greater sacrifices to obtain a clear arrangement. OF THE FORE-ARM. 243 ARTERIA DORSALIS POLLICIS. The small artery, or the two small arteries which, from going along the back of the thumb, are named arterise dorsalis pollicis, come off either along with, or immediately after, the dorsalis carpi. When there are two, they run both along the back of the thumb, one on one side, the other on the opposite side ; that which runs along the outer edge of the thumb passes through under the tendons, and is rather shorter : that which inclines to the inner side of the thumb is rather longer. These small arteries on the back inosculate round the edges of the thumb with the great artery on the inner side ; which is next to be described. The radial artery having advanced to the wrist, turns quick round the wrist, over the head of the radius, and under the tendons ofthe thumb ; it gives immediately before it passes the artery of the palm ; it gives immediately after it passes the ar- tery of the back of the hand ; it gives immediately after that the little arteries for the back of the thumb ; it then mounts along the thumb in that hollow which is by the side of the metacarpal bone of the thumb, till it arrives at the cleft be- twixt the thumb and fore-finger. There it divides into three great arteries ; one to the inner side ofthe thumb, very large ; another to that side of the fore-finger which is next the thumb, which branch is much smaller ; and one which exceeds these in importance, for it dives down into the palm of the hand, forms what is called the deep arch of the palm ; and which, having crossed the palm, forms on the side next the middle finger that inosculation betwixt the upper and lower arches which is so much celebrated. ARTERIA RADIALIS INDICIS. The artery ofthe fore-finger proceeding from the radial ar- tery is the first and smallest of these three branches. It goes off at the root of the metacarpal bone of the fore-finger, goes up along its interosseous muscle, and runs along all the edge of the fore-finger next the thumb, inosculating with die artery of the opposite edge, which comes from the ulnar arch ; it sends off twigs at its root, which inosculate with the small dorsal arteries of the thumb ; and it gives a branch to the abductor indicis. 244 ©F THE ARTERIES ARTERIA MAGNA POLLICIS. The chief artery of the thumb rises along its metacar- pal bone, a single artery, and there splits commonly, I think, into three smaller branches. Two of these run along the fore part of the thumb up to its extremity, and inosculate there ; the one running along the radial, the other along the ulnar side, till they meet at the point. These are, as it were, counterparts of the dorsal arteries, but greatly larger, the thumb being naked on the back, but fleshy where it looks to- wards the palm. Another branch of the arteria pollicis is one which turns across to the palm of the hand, and makes a smal- ler and more superficial inosculation with the palmar arch. ARTERIA PALMARIS PROFUNDA. The third branch of the radial artery-, and that by7 which it ends, immediately succeeds the artery of the thumb. It crosses the palm of the hand so as to form the deep arterial arch, or the radial arch of the pa-lm; it lies under the aponeu- rosis, and
s nearly of the size of a writing quill) usually comes off as a branch from the sciatic artery; it goes out from the pelvis along with the sciatic artery through the lower part of the sciatic notch, under the lower edge of the pyriform muscle, over the upper sacro-sciatic ligament. But no sooner has it made its appearance along with the sciatic artery, and emerged from the pelvis, than it returns into the pelvis again ; it does not go over the outside of the tuber ischii, and so down to the perin- aeum ; but it just appears out of the pelvis, rises over the up- per sacro-sciatic ligament, gives out a few branches, turns in again under the lower sacro-sciatic ligament, or rather under the spine or sharp point ofthe ischium, whence that ligament airises : it is now within the pelvis again ; it lies flat against the inner surface of the ischium ; it runs along by the direction of that bone till it approaches the symphysis pubis, where the root of the penis is. It there dives into the root of the penis, hav- ing just before given off that branch which goes to the peri- naeum. It is this long artery, running naked and unprotected along the whole inner side of the ischium, bending as the arch of the ischium and pubes bends, that is cut by ignorant lithoto- mists, which a broad gorget is sure to wound, and which can be safe only by our exchanging the gorget for the knife. The branches of the pudic artery are chiefly these :—First, Before it proceeds out of the pelvis it usually sends branches inwards to the neck of the bladder, vesiculae seminales, and prostate gland :—Secondly, When it emerges from the pelvis, and while bending over the sacro-sciatic ligament, it gives, like the sciatic artery, chiefly muscular branches ; it gives twigs to the sacro-sciatic ligament and pyriform muscle; others go to the gemini muscles, and turn over them to the great tro- chanter, and to the hip-joint, reaching as far as the acetabu- lum : others spread over the tuber ischii, to which they give arteries, which go outwards along the three muscles of the thigh which arise from this point; and it sends inwards from this part an artery which encircles the verge of the anus, and belongs to the sphincter and levator ani muscles. This branch is named the lower or external hemorrhoidal artery : and other branches it sends forwards into the perinaeum ; but these are smaller and less regular arteries ; they are not what are distinguished by the peculiar name of perinaeal arteries.— This artery, like the ischiadic, ends every where in inoscula- tions with the reflected arteries of the thigh. Thirdly, The artery returning again into the pelvis, and running along under the flat internal surface of the ischium, gives off many small branches to the bladder, prostate gland, vesiculie seminales, and rectum. But when it has reached 278 OF THE ARTERIES the perinaeum, and is about to emerge from the pelvis a se- cond time, and go into the root of the penis, it gives out three chief arteries ; one to the perinaeum, one to the body of the penis, one to the back of the penis thus : When the artery has approached nearly to the musculus transversalis perinaei, it splits into two branches ; one of which is the artery of the perinaeum, the other is the proper artery of the penis. ARTERIA PERINjEI. The artery ofthe perineum passes under the transversa- lis perinaei, and betwixt the accelerator and erector penis ; in short, it comes out from that triangular cavity which we cut into in lithotomy ; in which operation of course this branch cannot escape. The artery having escaped from this triangu- lar cavity, runs forwards along the perinaeum for two or three inches, according to the size ofthe subject, growing very sen- sibly smaller as it goes along. It is chiefly for supplying the skin and muscles of the perinaeum ; and gives these branches : 1. When it has just come out from the triangular hollow, it gives off from its root one branch at right angles, which goes directly across the perinaeum : it keeps the course of the trans- verse muscle; it may be named arteria transversalis perinei, and ends about the sphincter ani. 2. It gives bran- ches to the accelerator and erector muscles. 3. It gives branch- es to the scrotum ; and being continued along the corpus cavernosum of each side, it ends upon the tendinous sheath, which binds the corpora cavernosa. Thus ends the perinaeal artery. arteria penis. The proper artery of the penis is the continued trunk of the pudic artery-. It is much larger than this perinaeal branch ; is as big as a crow-quill; it keeps still close to the bone, while the perinaeal artery goes outwards ; it at last touches the sym- physis pubis, and of course pierces the corpus cavernosum, just where it takes its rise from the leg ofthe pubes : and h. re it splits into two great branches ; one to the corpus caverno- sum, and one to the back of the penis, or rather into three, since there is one also for the bulb of the urethra. The bulb of the urethra is quite insulated in the perinaeum, while the corpora cavernosa arise from the bone. Now, first, OF THE PELVIS. 279 as the artery of the penis is passing by the side ofthe bulb, it gives off an artery to the bulb sidewise, which in part plunges into the bulbous substance, and in part is scattered upon the accelerator, prostate gland, &C. Secondly, The artery having risen to the place where the root of the corpus cavernosum is, gives off that artery, which runs small and delicate along all the back of the penis, till it ends at last in a branch which encircles the corona glandis.__ This is named the arteria dorsalis penis. Thirdly, The artery now plunges deep into the proper sub- stance of the penis ; the artery of each side goes into each corpus cavernosum at its root, and splits into two branches ; these run chiefly along the septum, or partition betwixt the cor- pora cavernosa of each side. It is this artery which pours out blood so freely into the cells of the penis, and causes erection. These three, the glutaeal, the sciatic, and the pudic arteries, are the only ones which go out from the pelvis behind, and one only goes out by an opening on its fore part, viz. the obtu- rator artery. ARTERIA OBTURATORIA. The obturator artery is so named from its passing through the thyroid hole. No artery is less regular in,its ori- gin ; arising sometimes from the Iliac, sometimes from the Hypogastric, and not unfrequently from the root of the Epi- gastric artery7: in which case it turns back again over the pu- bes, coming into the pelvis through the ring. But no artery is more regular in its destination ; a large artery always passes through the thvroid hole ; the thick muscles in the centre of the thigh cannot want it. The obturator artery, arising from the iliac or hypogastric, runs along by the upper edge of the pelvis, by the lower edge ot the psoas muscle, accompanied with the obturator nerve, which is to go through the hole along with it. Having arrived at the fore part of the pelvis, it slips through the oval hole by a very small opening, which is in the upper part ofthe tendinous membrane, which closes that hole, and which is consequently at the upper edge ofthe obturator internus muscles. The ar- tery, before it passes out of the pelvis, often gives branches of considerable size downwards to the neck of the bladder, pros- tate gland, and vesiculae ; to the iliacus internus and psoas muscles, and to the lymphatic glands which lie upon them ; and there is always a branch, which encircles thc upper part 280 OF THE ARTERIES, &C. of the foramen thyroideum, lies close upon the bone, and give* its twigs upwards into the muscles of the belly. After the artery has passed along with its nerve through the thyroid hole, it comes into the very heart or central part of the thigh. Almost all its branches are muscular; none are worth distinguishing by name ; it is only the general tendency of the artery that needs to be explained. It divides into two chief branches, taking opposite directions. The first is deeper ; it turns downwards and outwards towards the hip- joint. It performs three services here; it gives first arteries to the periosteum, to the capsule, and to the gland within the acetabulum ; it gives also large branches to the obturator quadratus femoris, and all the great muscles which immedi- ately surround the joint; it also forms very large and import- ant anastomoses round the joint, with the sciatic and pudic arteries from the pelvis, and with the reflected arteries from the thigh. The more superficial branch of the thyroid sends all its branches into the great muscles upon the inner side of the thigh coming from the pubes. Its chief branches are to the upper part of the triceps muscle ; it sometimes gives branches even to the superficial muscles, as the gracilis and sartorius ; always, at least, small twigs pass through these muscles to the skin of the thigh and to the scrotum. Of these two arteries, this superficial one encircles the inner edge of the thyroid hole, or that which is next the pubes, with one of its branches; while the deeper artery encircles the outer edge, or that which is next to the hip-joint, so that they meet upon the bone inos- culating with each other. ( 281 ) CHAP. IV. ARTERIES OF THE LOWER EXTREMITY. ILIACA EXTERNA. i. he external iliac artery is that branch of the com- mon iliac which descends under Poupart's ligament into the thigh. The internal iliac or artery of the pelvis parts from this within the pelvis at the joining of the ilium and sacrum. The external iliac passes down into the thigh, by bending along the upper edge or brim of the pelvis, directed by the lower edge of the psoas muscle, which also descends into the thigh. This great artery is accompanied by the anterior crural nerve; its corresponding vein lies by the side of it; the lymphatics of the thigh creep upwards along this artery into the pelvis ; and when the artery descends into the thigh, it passes so over the bulging part of the acetabulum and head of the thigh-bone, that it is felt projecting there and beating with amazing force. The projection by which the artery is thus thrown forwards is not merely the naked pelvis and the head of the femur ; these parts are covered by the flesh and tendons of the psoas magnus and iliacus internus, which also come out from the pelvis to the thigh. The artery lies cushioned upon these muscles ; the muscles dive very deep to get at the trochanter minor or posterior trochanter of the thigh-bone. The artery follows them ; and thus it is plunged as it were into a deep cavity, assumes a new position, and this constitutes a second point of description. The hollow in which the artery now lies may be compared with that of the bend of the arm. The artery now takes the name of femoral, lies deep in a hollow, surrounded by much fat and many glands ; the cavity- is covered with a very strong fascia, or tendinous sheath, which descends from the muscles of the belly over Poupart's ligament, and which is greatly strengthened at this point by the general fascia of the thigh. Here the femoral artery, instead of sending off less effectual branches from point to point as it moves downwards, and which could not have conveniently penetrated through all the thickness of the thigh, sends off one great branch, which Vol. II. 2 N 282 OF THE ARTERIES furnishes all the thigh without exception, whence it is named the muscular artery- of the thigh. This great artery goes off from the femoral just like the ulnar from the artery at the bend of th*. arm, i. e. very deep among the muscles, in the triangu- lar cavity above described. Thence it is oftener named pro- funda than muscular artery. The femoral artery having sent down this great branch, equal almost to itself in size, inclines outwards again, meets the inclined line of the sartorius and follows its oblique direc- tion, assuming a new character ; for now it becomes a second time quite superficial, is covered by nothing besides the strong fascia of the thigh and by the skin. It is felt beating along the line of the sartorius muscle ; and by that line we apply the cushion of our tourniquet. It requires from our feeling only about two hands breadth, or a little more, above the joint of the knee ; at which place it perforates the triceps or great muscle of the thigh, gets from the fore to the back part, or, in other words, forsakes the thigh to go down behind into the ham, where it exchanges its name for that of popliteal artery. The popliteal artery, when it has got into the ham, meets with its corresponding nerve, which is of vast size ; and the artery lies now flat upon the back part of the thigh-bone, passes down in a hollow formed betwixt its great condyles, lies flat upon all the back of the knee-joint, is enclosed by the two great hamstring muscles from above, and by the two great heads ofthe gastrocnemii muscles below. But although we say- it is protected, yet in truth it is not tightly bound down by a fascia embracing it, but lies on the contrary so loose and un- supported among the cellular substance, that we have the most certain evidence of its being often racked and strained in sudden or awkward motions of the joint. From the ham the artery descends into the leg, under the heads of the gastrocnemii muscles ; and being lodged behind the great bulging, or head of the tibia, below the joint, it there divides into three great arteries. One passing down behind the tibia is named posterior tibial artery ; one perforat- ing the interosseous membrane goes down along the fore part of the tibia, is named tibialis antica; the third artery, passing down behind the fibula, is named the fibular or peronaeal ar- tery. These may be justly compared with the three arteries of the fore-arm ; and as those meet in arches upon the palm of the hand, these meet and form similar arches on the sole of the foot. Even from this slight and general description of this import- ant artery, many conclusions may be deduced not indifferent OF THE LOWER EXTREMITY. 283 to the surgeon ; for there are several points in the course of this artery very peculiarly marked. First, It is thrown so forwards by the bulging of the pubes, where it forms the socket for the thigh-bone, it beats so strongly just under tlie rim of the belly, that we cannot, at least till we try7, doubt of its being easily compressed. I see, indeed, that Acrel, in very desperate circumstances, when his ligatures had given way even before his eyes, and the arteries burst, and after the surgeons had been twice deluged with the blood of the femoral artery, thought that he had suppressed this artery, by resting on it with his thumbs. But indeed the poor patient, under these horrible circumstances, as Acrel justly calls them, must have fallen so faint and low, by a tedious alarming operation, and by the repeated bleedings, that any thing might have suppressed the pulse in the femoral ar- tery7, when that ofthe heart itself was well nigh gone.* But this is one of the points in which it is -the most necessary for every man to speak from his own experience. I have tried it in the most favourable circumstances in a slender young man ; and when I thought mvself sure of the point, behold the blood gushed out with a whizzing noise and prodigious force. I have seen others try it, and fail. It is perhaps not impossible to compress the femoral artery ; but it is not an easy thing, and is an expedient never to be trusted where the life of a fel- low-creature is immediately in danger.—Secondly, the strong covering of the fascia gives a peculiar form to the aneurism of the thigh ; it keeps it flat, forces the blood to spread abroad into the surrounding parts ; and this deep driving of the blood among the muscles, together with the great size of the sac, and the putrefaction of three or four pounds of blood, causes that gangrenous and sloughing condition of the parts, by which we are so often foiled in our best concerted operations, and after the artery has been well and fairly tied.—Thirdly, it is very obvious that the profunda might with more propriety be named the femoral artery, since it is the proper artery of the thigh ; and though Heister, and some of the best among the old surgeons, spoke of this division as one which only some- times took place, we know that a leg could no more be without a profunda than without what we call the femoral artery ; and we also perceive, notwithstanding the doubts and fears of some modern surgeons, that when the femoral artery is wounded, it • « His in horrendis angustiis, cum nee nova ligatura, nee torcularis contrac- tione hxmorrhagia sisti posset, in trunco ipso dum ex inguine prolabitur, pollici- bus firmiter admotis, compressionem institute plecuit, quo effluxus substitit." 284 OF THE ARTERIES is after all only a wound of the artery of the leg.—Fourthly* The large branches which the profunda sends upwards round the haunch, inosculating with the sciatic and pudic arteries, and the branches which it sends downwards to the knee, inos- culating round that joint with the arteries of the leg, make this branch of peculiar importance to the surgeon ; for when the artery is wounded in the groin, above the profunda, this branch saves the thigh, by its inosculations round the haunch ; and when the artery is wounded in the thigh, below the profunda, or in the ham, it saves the leg by its inosculations round the knee ; and when the whole line of the femoral artery has been obliterated, it has saved the whole extremity, as I have else- where proved, by receiving the blood from the arteries round the haunch, and conveying it down to the arteries below the knee, being thus an intermedium betwixt the internal iliac ar- tery and the arteries of the leg, capable of forming a new line of circulation behind the thigh when that before is shut up.— Nor should it be forgotten, that the aneurism on the fore part of the thigh may be from the profunda; and then the femoral artery which lies before it may be cut across by a rash or igno- rant surgeon. Fifthly, The place of the femoral artery passing through the triceps muscle is next to be observed, for these reasons.— At that point it lies close upon the bone ; and as this happens exactly at that distance above the knee at which we usually amputate, we expect in such amputations to find the great ar- tery close by the bone. As the artery is at this point tied down by the tendon of the triceps, and is in fact passing through.a tendinous ring, it sometimes happens that when we have cut near this, but not upon it, the flesh shrinks in such a way that even this great artery, though it bleeds, is not easily found ; but one stroke of the scalpel, running along the bone, cuts the tendon up, and exposes the artery with open mouth.— This single point makes all the difference betwixt an aneurism ofthe thigh and of the ham ; it is peculiarly necessary to mark this, in order to ascertain the extent of the disease before be- ginning an operation. Nothing can have a worse appearance than that which has actually happened, viz. a surgeon begin- ning that operation in the ham, which he should have attempt- ed rather on the fore part of the thigh : and being forced to change his ground, and to begin a second operation on the fore part ofthe thigh, or, what is worse, to cut up the tendon, and follow the diseased artery7 to the fore part ofthe thigh, cutting, in short, first longitudinally betwixt the hamstrings, and, after an hour's working perhaps, cutting crosswise to reach the fore part of the thigh. OF THE LOWER EXTREMITY. 285 6thly, Is it not a matter of very high importance to study the ham still more carefully than the axilla, since the artery is so often hurt at this place by rude motions of the joint ? For it is a narrow cavity ; the artery lies close upon the joint and bones ; and when it is allowed to remain long in a diseased state, enlarging and dilating the ham, we perform in the end a hopeless operation ; or, if we had hopes when we began our operation, they are all over before it is ended: for the parts are found to be diseased, the bones carious, the joint spoiled : there is no hopes even of present safety, and of the ligature hol- ding, and much less any expectation of a permanent cure.— Often the greatest surgeons have been contented to finish such an operation by cutting off the limb ! 7thly, When the artery has gone down beyond the ham, and seems lodged safely under the gastrocnemii muscles, still it is not safe ; it is bended tense over the back of the joint; it is pressed by the gastrocnemii stretching over it; and their violent action has often been such, as to have torn the artery with a tumour so immediate, and with such excruciating pain, that the surgeon has been constrained in a manner to cut off the limb even upon the spot. 8thly, Very often we are obliged to decide, whether a tu- mour of the thigh or a tumour of the ham can be cut away only by our knowledge of these arteries. How often the anterior arteries ofthe leg are cut by workmen, and how much they are exposed to the stroke of the adze or axe, every practical sur- geon must know : but the mischances that open arteries are quite unthought of. I have known a man standing carelessly by his scythe, which was set upright, the blade along the ground, and the shaft resting upon his arm, cut the artery behind the outer ankle so as to form (when the wound healed) a large, livid, and strong beating aneurism, ready to burst, and requiring immediate operation. The epigastric artery is in danger in operations for hernia. The femoral artery is the subject of frequent operations ; the popliteal aneurism is a disease of this artery in the ham ; and even the simple operation of amputating either the limb itself, or tumours in the thigh or ham, requires a perfect knowledge of all these arteries. But although no formal operation affected these lesser arte- ries yet the main artery itself is so exposed, and so superficial where it runs down the thigh, that it is wounded in a hundred various ways. It is very singular how often it has been wound- ed by one particular accident, viz. the dropping of a pair of scissars, and with a sudden instinctive effort clapping the knees together to catch them. It has been wounded once or twice 286 OF THE ARTERIES, &C. b)7 a shoemaker clapping his knees thus together to catch his sharp-pointed paring-knife. One of my pupils lay three months in London, uncertain whether his femoral artery was wounded; for he had in this way catched his pen-knife, the point of which had run into his thigh, and wounded some great artery7. It has been cut across by balls ; it has been wounded even by a single slug ; it has been uncovered by wounds which yet did not touch its coats, and has in consequence dilated into an aneurism. I have known a boy stab another with a pen- knife in the thigh, and strike so critically as to open the artery with a wound like that of a lancet. My friend Mr. Hark- ness gave me the privilege of dissecting an aueurismal limb which he was obliged to cut off; and in which the artery was (if I may use such an expression) broken or torn across the upper end of the thigh-bone, which had been broken by a fall about three weeks before. Ail these accidents must come upon the surgeon very sud- denly ; and if they come upon him unprepared, iii is in a mo- ment lost. I once saw a fine young fellow die from this alarm of the attendants and confusion ofthe surgeon. He was a tall, stout, young man, who w-as sitting at table with his compan- ions eating bread and cheese, taking his glass, and telling his tale. He had in his hand a sharp-pointed table knife, which he happened to hold dagger-wise in his hand, and in the height of some assertion or oath he meant to strike the table, but the point missed, and slanted .over the table ; he had stab- bed himself in the femoral artery, and with one gush of blood he fell to the ground. When I came, I found the young man stretched out upon the floor; he was just uttering his last groan; the floor was deluged, all slippery, and swimming with blood. The wound was covered with a confused bundle of clothes, which I instantly whirled off; and in that moment two gentlemen, who had been first called, and who had both run off for tourniquets (because tourniquets are used to stop bleedings,) returned ; and had the unhappiness to see that the hole was no bigger than what I could close, and had actually shut up with the point of my thumb ; and which, had it been shut and put together with a good compress, would have heal- ed in three days, forming a large beating aneurism within, allowing time for a deliberate operation. In short, to enumerate the variety of accidents which may affect this artery would be impossible ; but surely from the little that I dare venture to say in this place, it must seem one ofthe largest, the most exposed, and most dangerous, and by all this the most important, artery in the body ; and from these FEMORAL ARTERY. 287 previous hints and general descriptions, the value ofthe several branches which are now to be enumerated will be more easily felt and understood. ,& BRANCHES OF THE FEMORAL ARTERY. ABOVE THE GROIN. The femoral artery above the groin, that is, just be- fore it passes from under the sacro-sciatic ligament, gives off two very singular arteries, which turn backwards and never appear in the thigh ; the one, going upon the fore part of the belly on the inner side, is the epigastric artery ; the other, turn- ing backwards along the inner surface of the haunch-bone, is named circumflexa ilicum. arteria epigastrica. The epigastric artery, so named from its running up along the belly, goes off from the inner side ofthe femoral ar- tery about an inch before it passes out into the thigh. The epigastric, when first given off, turns downwards with a full round turn till it touches Poupart's ligament. The pe- culiarity of its course here must be very carefully attended to. The femoral artery lies at the very outer margin* of the open- ing, called the crural arch. The Fidlopian ligament forms the upper line ofthe crural arch. The epigastric artery moves in- wards and downwards with the Fallopian ligament, running along its lower edge ; then it crosses the opening called the ab- dominal ring, behind the ring, and also behind the spermatic cord which passes through the ring ; then it mounts by the border of the transverse muscle, and gets to the rectus muscle of the belly ; but it is pretty high before it touches the side of the rectus, and lying on the outside of the peritoneum, and on the inner surface of the rectus muscle, and keeping in the di- • Viz. that end of the slit or arch which is nearest to the haunch-hone. 288 BRANCHES OF THE rect line of the rectus muscle near its centre, or rather nearer the outer edge of the muscle, and inclining inwards, it mounts from the groin to a little below the borders of the thorax, when it inosculates very freely with the internal mammary artery.— These are the inosculations which were mentioned, page 213. Through its whole course this artery is so large as to make its wounds important: we should know where to stop it in wounds ; we should remember to avoid it in opening or extir- pating tumours. I have seen some confusion and much loss of time during an operation, from not attending to this. The main artery must be remembered ; its branches are of litde value. The only branches which it is at all necessary to men- tion are, first, one small twig, which it sends downwards along the spermatic cord ; soon after entering under the abdominal muscle, it gives off a large branch almost equal to the artery itself, which goes directly towards the navel, and ends there. This branch goes obliquely across the muscle, while the main artery follows the general line ofthe muscle, and gives branches on every side to the rectus, transversalis, obliquus ; in short to all the muscles of the abdomen, and spreads its last branches very freely about the lower border of the chest. ARTERIA CIRCUMFLEXA ILIUM. The circumflex artery of the haunch is named cir- cumflexa from its turning directly backwards, and ilium from its passing along the hollow of the haunch-bone. It is smaller than a crow-quill; it goes off from the outside of the femoral artery opposite to the epigastric, or rather a litde lower ; exactly at that point where the outer end of the Fallopian ligament begins in the haunch-bone. It runs back- wards in a curved line along the hollow of the haunch-bone, curving along with the crista ilii, or ridge of the ilium, under which it lies. Its line is along the most naked part of the bone, where the internal iliac muscle begins on one hand, and the transverse muscle of the belly on the other ; in short, it runs along all the upper edge of the internal iliac muscle, quite round almost to the lumbar spine, where it joins the ileo-lumbar ar- tery by small inosculations ; for at this place the reflected iliac artery, which grows gradually and sensibly smaller, is almost spent. There are no remarkable branches which deserve to be described or even to be named, unless it be one which goes off early, near the head of Poupart's ligament, and gives branches to the ligament, to the sartorius muscle which arises at the same point of the haunch-bone, and to the edge of the iliac FEMORAL ARTERY. 289 muscle. And as it runs along betwixt the iliac muscle on the one hand, and the transverse of the belly on the other, it gives many branches downwards to the internal iliac and psoas mus- cles, and to the substance of the bone ; and upwards it gives three or four branches into the abdominal muscles, which go so far along the belly as to inosculate with all its other arteries. <© BELOW THE GROIN. These last branches, viz. the epigastric and reflected iliac arteries, I ascribe to the internal iliac; for the artery is still within the abdomen, or at least not without the arch of the thigh. The femoral artery, until it gets down into the hollow which I have described, gives no branches, or none with which I would choose to confound the description of the profunda or great artery of the thigh. The branches which the femoral gives off before that are only small twigs to the fat, glands, skin, or private parts ; but one or two of those to the private parts are sometimes large.—First, twigs go out along the fe- moral ligament, and terminate in the skin.—Secondly, twigs go to the fat, and lymphatic glands of the groin.—Thirdly, there ascends a small branch, sometimes towards the origin of the sartorius, to the middle glutaeal muscles, and to the begin- ning of the fascia lata.—Fourthly, Of those branches which go across the upper part of the thigh to the genitals, and which are named pudicjE externa to distinguish their branches from those of the pudica communis, there are usually three. The uppermost is scattered about the fat of the pubes. The middle one goes across the heads of the triceps ; it is longer and larger than the others ; it goes to the side of the scrotum and penis in Men ; in Women it is large, and runs into the labium pudendi. The lower one of the three goes to the lower parts of the scrotum, and to the skin of the thigh near it. ARTERIA PROFUNDA FEMORIS. Then comes off the profunda femoris, the deep or muscu- lar artery of the thigh. It arises from the femoral artery about four inches below the groin, more or less according to the size of the subject. It turns off from the femoral artery Vol. II. 2 0 290 OF THE femoral artery. with a bulging, which looks backwards and towards the out- side of the thigh. It lies deep in the triangular cavity, upon the face of the iliacus internus and pectinalis muscles. It presendy gives off two great arteries, which turn upwards along the joint; one round the outer side, the other round the inner side, of the joint. Then it passes downwards, turns in behind the femoral artery, sinking deeper and deeper towards the back parts of the thigh. It passes down along the face of the triceps muscle ; and as it moves along its fore patrt, it sends through three or four great arteries to the back part, which are called the perforating arteries of the thigh. And, lastly, the profunda itself, or its last branches, passes through the tri- ceps ; and this last branch is named perforans ultima vel de- scendens femoris. arteria circumflexa externa. The circumflex artery, which goes to the outside of the hip-joint, proceeds from the very highest point ofthe pro- funda. It takes its course outwards, passing under the sarto- rius, fascialis, and head of the rectus : it runs over the ten- dinous head of the vastus internus, where that muscle takes its rise from the outer trochanter : it divides very early into the following branches—First, Branches go to the inner side, to the internal iliac muscle, upon which this artery lies ; and round it they bend over the lesser trochanter, making inoscu- lations with the internal circumflex artery.—Secondly, an ar- tery goes in the opposite direction, viz. outwards, to the iliac muscle, the sartorius, the head of the rectus, the fascialis, and round to the glutaeal n uscles.—Thirdly, it sends many lesser branches upwards and forwards into the heads of those mus- cles which I have just enumerated, and which lie immediately over the artery.—Fourthly, it sends large branches round the root of the great trochanter, some of them going into the hol- low above the trochanter; others keeping so low as the root of the trochanter, where the greater glutaeus is inserted.—Fifthly, The most important of all its branches is a very long one, which it sends directly downwards under the rectus, or be- twixt it and the vastus internus muscle. This artery is divided into two great branches, which run down the whole length of the thigh, somewhat resembling in their shape the profunda humeri : they are named the greater and lesser descending branches of the circumflex artery, and they inosculate in a most particular manner with a large anastomosing branch from the femoral artery. The larger branch of this artery emerges OF the femoral artery. 291 from betwixt the rectus and vastus externus, a little above the knee, to inosculate with one of the articular arteries of the knee. Its smallest branch inosculates with the anastomosing branch of the femoral artery. The two anastomoses seem to be the chief use of these two long arteries, though they do also send some branches to the muscles. But to give a more simple notion of this circumflex artery7, it should be described thus. It is divided into three chief branches : 1st, A descending branch, which goes down to the knee-joint; 2nd, A transverse branch, which crosses the up- per part of the thigh, and turns round the neck of the thigh- bone ; 3dly, It sends a less important branch up upon the dorsum ilii. ARTERIA CIRCUMFLEXA INTERNA. The internal circumflex artery is a thick short artery, which goes off opposite to the ball of the thigh-bone ; and as the external one goes round the great trochanter, this goes round the lesser trochanter. It is a smaller artery ; it has not so many muscular branches ; it keeps closer to the joint; it goes off from the inner side of the profunda, just opposite to the circumflexa externa, or a little lower, but never more than an inch lower ; it passes over the insertion of the psoas mus- cle, and under the belly of the pectinalis ; it attaches itself then to the lesser or inner trochanter, and goes round the neck of the thigh-bone round the joint, and is expended on the muscles at the back of the joint, as the quadratus femoris, ^The artery having turned towards the inside, the muscles which lie there are the triceps gracilis, &c. The first branches, therefore, which this artery gives off before it passes under the pectinalis, are to the triceps and gracilis. After having passed under the pectinalis, and while it is turning round the root of the lesser trochanter, it gives branches to the pectinalis and triceps ; and especially it gives to the capsular ligament ot ti,e n^- oint an artery winch '^^f^^^fih, The artery now lying upon the pelvis, under the neck ot tne thigh-bone,^dividesy itfelf into two chief arteries ; one goes Sards and forwards along the triceps, till it ends at last roCd the symphysis pubis. The chief muscular twigs of this branch are given to the triceps, and to the obturator muscles ; Shis branch which inosculates so freely with the branches of the obturator artery ; it is a twig of this artery which enters °nto the cavity of the hip-joint, by that breach which is in the 292 OF THE FEMORAL ARTERY. inner edge of the acetabulum ; and this branch entering then by its proper hole, goes to the gland in the bottom of the socket, or chiefly to it. The other branch turns away in the opposite direction, viz. backwards betwixt the little and the great trochanter, turning round the neck of the thigh-bone. It gives branches also to the triceps and obturator, inosculating with the obturator artery. But its chief branches are towards the other side, as to the capsule of the hip-joint, to the neck of the thigh-bone, to the quadratus femoris. It is this artery which gives most of those branches about the roots of the Drochanters named trochanteric arteries ; and it is from \his artery that many branches go backwards along the tuber ischii, to unite with those of the sciatic and pudic arteries. of the perforating arteries. The two first perforating arteries are very large ; the tw« next perforating are smaller and less regular ; the fifth perfor- ating artery is jtist the termination of the profunda. But still it must be understood, that these perforating arteries are ex- tremely irregular in place, size, and number, as indeed all muscular arteries must be; and that there are, besides the greater perforating arteries, many like them in this part of the thigh, though not distinguished by name. ARTERIA PERFORANS PRIMA. The first perforating artery is the largest branch of the profunda, bigger than both the articular arteries joined. It arises from the profunda, just under the lesser trochanter, betwixt the pectinalis and triceps brevis ; and perforates the triceps about an inch below the trochanter, and close upon the thigh-bone. Here the artery lies under the lower edge of the glutaeus, and close by the origin of the biceps, semi-tendinos- us and semi-membranosus muscles, the three muscles which form the hamstrings ; and the chief division of the artery is into one great branch, going upwards along the glutaeus, and another going downwards along the flexor muscles. First, the artery which goes upwards turns over the glutaeus, spreads innumerable branches about the great trochanter; and meeting with the trochanteric branches of the arteriae reflexae, make a most beautiful inosculation, or rather net-work of inoscula- tions, over the trochanter. Another transverse branch of this upper artery turns quite round the lower part of the trochanter, ©F THE FEMORAL ARTERY. 293 and round the thigh ; among the flesh of the vastus internus ; and a third branch of the same artery meets in inosculation with the lower branches ofthe sciatic artery. The lower or descending branch ofthe perforans prima goes down along the three flexor muscles ofthe leg, viz. the biceps, semi-tendinosus, and semi-membranosus ; nourishes their fleshy bellies, and plays over their surface in beautiful net- work. arteria perforans secunda magna. The second or great perforating artery is a much larger and more important branch of the profunda than this first, at least it is so when the other perforating branches are wanting, and when this, as often happens, represents the con- tinued trunk of the artery : but I shall describe it as a second perforating artery, to be succeeded by others.* The second perforating artery comes off from the profunda, about two inches lower than the first; it passes through betwixt the first and second heads of the triceps, or through the flesh of the se- cond ; and turning obliquely downwards and backwards, close by the thigh-bone, it passes into the cellular interstice betwixt the flexor muscles of die opposite sides, i. e. betwixt the bellies of the hamstring muscles, and ends there. Before it passes through the triceps, it gives branches to the triceps, and vastus, and to the great trochanter, and to the thigh-bone. Its two chief branches, after it perforates the tri- ceps, are, first, one great transverse branch, which goes di- recdy across below die tendon of the glutaeus, and gives one great branch up upon the glutaeus, and another to the vastus externus, making inosculations with the reflected arteries of the joint. Secondly, Its descending branch goes down in the hollow betwixt the great hamstring muscles, and its branches go into both muscles, but chiefly into the biceps, and in these the artery is exhausted. arteria perforans tertia. The third perforating artery comes off about a fin- e's breadth lower than the former; it makes a gende waving • My reason for saying this is, that sometimes there are but two perforating teries, while there are often fire which need to be described. 294 OF the femoral ARTERY. turn inwards before it pierces the triceps ; and after having perforated the triceps, it gives its branches to both the ham- string muscles, but chiefly to the semi-tendinosus. ARTERIA PERFORANS QJJARTA. The fourth perforating artery may be regarded as the last, or as the termination of the profunda, though some- times there is a fifth. It perforates again still lower, about a finger's breadth below the last, through the flesh ofthe triceps magnus. Its first branch, while on the fore part of the triceps, is the nutritia magna femoris, or proper nutritious artery of the thigh-bone ; and after it perforates the triceps, it gives its ar- teries to the two hamstring muscles, but more especially to the biceps ; and so this last branch of the profunda ends. But this minute description of any important set of arteries never presents any clear idea to the reader's mind, nor any knowledge which he can easily retain. I expect rather to do so by one short description. The title of perforating arteries is one which compre- hends all the great muscular branches of the profunda, except the two reflex arteries belonging to the joint. They vary in number, as all muscular branches must do, and are proportion- ed in size and number to the bulk ofthe thigh. The profunda passes down along the fore part of the triceps, while it is giving off these arteries ; they must, of course, perforate the triceps before they can get to the back part of the thigh. When they do perforate, they come into a great muscular interstice or hol- low, which is formed by the hamstring muscles of opposite sides, by the biceps on one side, and by the semi-membramo- sus and semi-tendinosus on the other. It is to these two great muscles of the back part of the thigh that the branches of all the perforating arteries are chiefly directed. Each perfo- rating artery succeeds another at about the distance of an inch or more ; each successively coming out into this uiterstice at a lower and lower point. Each artery gives branches to the tri- ceps, Sec. before it perforates, and to the hamstring muscles, Stc. after it has come into the hollow. The two first perfora- ting arteries are the only arteries which are large and abso- lutely certain ; the third is always very much smaller ; the fourth is generally the termination of this great artery ; the fifth perforating artery is rare. Such a general idea as this of their size and value, and situ- ation in the very heart or deepest part of the thigh (for the profunda turns backwards from the very first, and all its OF THE FEMORAL ARTERY. 295 branches keep the same direction,) is of more importance than a particular knowledge of every branch of each perforating ar- tery ; a thing really unattainable, since they vary more in their ultimate branches than almost any other arteries in the whole body ; for they have more space, and a greater mass of irregu- lar muscle to wander in, and produce varieties. ARTERIA FEMORALIS. Though the profunda is plainly the artery of the thigh, yet from the ignorance of anatomists and surgeons (who never knew till about twenty years ago that there was more than one great artery) the superficial artery has been named the artery of the thigh. The femoral artery makes a spiral or serpentine turn round the whole thigh. It appears first on the fore part; it turns obliquely round to the inner side, following the lower edge of the sartorius muscle ; it passes through the triceps, after it has got about two-thirds down the thigh, by which it gets into the ham, and its spiral turn is completed. It lies deep where it is giving off the profunda ; it rises then, and is superficial all along the middle ofthe thigh ; and when it has advanced two- thirds down the thigh, it again gets too deep to be felt; but all along it is covered by the thick strong fascia of the thigh.— Through the whole of this course it gives no one branch out that is of any considerable importance. They are all muscu- lar arteries, very small, nearly of one size, nameless, and un- distinguished, going into the muscles of the fore part of the thigh ; or if any are distinguished, it is only by their relation to other arteries, when the trunk gets low enough to make anastomoses with the arteries of the joint. The nameless muscular branches of the Femoral artery, go, in one word, to all the muscles on the fore part ofthe thigh; to the rectus, sartorius, vasti, gracilis, and triceps ; to the glands, fascia, fat, and skin ; and it thus continues giving successive branches to each of these long muscles cs it passes the several points of them. There is no distinguished branch till, having arrived within two hands' breadth ofthe knee-joint, it gives out (just whert- it is about to pass through the tendon of the triceps) a larger branch named (like a similar branch of the humeral arter\) RAMUS ANASTOMOTICUS MAGNUS. This branch goes out from the inner side of the femoral ar- 296 OF THE FEMORAL ARTERY. tery just where it is about to perforate the triceps ; it passes into the flesh of the vastus internus ; it first sends smaller branches to the vastus internus and sartorius, and through the interstice of these two muscles to the skin of the knee. But having penetrated into the fleshy belly of the vastus internus, this artery, which is itself very short and thick, sends out its slender inosculating branches : one goes downwards along the tendon of the great triceps; and when the tendon of that muscle- stops above the inner condyle, this artery goes forwards over the condyle, makes a net-work upon it, joining in numberless inosculations with the articular arteries from below, and gives twigs also into the joint. The other branches of this ramus anastomoticus tend all forwards and upwards to join the de- scending branches of the reflexa externa, which come down along the rectus muscle. There are two other arteries lying close upon the joint, re- markable enough to deserve a name, and they are called perfo- rating arteries ; not perforating like the branches of the pro- funda, to get deeper among the flesh ; but perforating so as to get out from trfe cavity of the ham upon the surface of the thigh again. The upper perforating artery arises from the inner side ofthe popliteal artery, just after it has perforated the triceps ; but it must not be accounted a popliteal branch, because it im- mediately perforates the triceps muscle again. It gives branch- es to the semi-tendinosus, semi-membranosus, and sartorius ; in short, it turns its branches towards the muscles on the inner side ofthe knee, and is a smaller artery7. The lower or second perforating artery goes off near- ly opposite to this. It is a much larger artery. In order to escape from the ham, it perforates the shorter head of the bi- ceps, or outer hamstring muscles. It first crosses the ham at its very upper point, and within the substance of the triceps ; it then perforates the shorter head of the biceps flexor-cruris ; it then emerges upon the thigh by the belly ofthe vastus externus muscle. Before it passes across the ham, it gives a branch to the semi-membranosus : while it is passing through the flesh ofthe biceps, it gives a lower nutritious artery to the lower and back part of the thigh-bone ; after it perforates the biceps all its branches are given to the flesh of the biceps and vastus ex- ternus, and its extreme branches are spent in inosculation with the descending branch of the reflex or articular artery of the hip-joint. But these branches, which are the last ofthe femoral artery, are extremely irregular. There is no artery from the profun- of the popliteal artery. 297 da downwards worth naming, not even those which I have just described.* popliteal artery. The artery having passed through the ring or tendon of the triceps which is formed for it, or rather having passed betwixt the triceps and the bone, lies flat against the flat part of the thigh-bone as deep as possible in the cavity of the ham. There, as no muscles are lodged, it can give no muscular arteries of any importance ; none but trivial ones to the hamstrings or to the heads of the gastrocnemii. In its whole length from the place of its perforating the triceps tendon to its great division, which is under the longer head of the solaeus muscle, it gives none but articular arteries, i. e. small arteries to the knee- joint, which are no less than five in number, and encircle it in all directions. First, The popliteal artery sends off from each side two muscular branches, not deserving a particular name nor des- cription ; the one goes to the biceps or muscle of the outer hamstring, the other to the semi-tendinosus and sartorius, or inner hamstring muscles. Then come off the arteries of the joint, which are thus ar- ranged ; 1. The upper arteries coming off above the joint are three in number ; one turning round the inner side of the joint, and one round the outer side, and one in the middle ; whence it is named azygous, as having no fellow. 2. The arteries be- low the joint are two only in number; one to the inner side, and one to the outer side, of the joint; and these directions of the arteries settle both the order of description and also their names. ARTERIA ARTICULARIS SUPERIOR EXTERNA. That upper articular artery which comes off above the knee, and which turns round the outer side of the joint, arises from the popliteal artery above the outer condyle ; its trunk is * « Confiteri tamen oportet, binos ultimos ramos in distribuendis suis surculig infinite ludere, ita ut descriptione ad quod cunque cadaver adaptata vix, ac ne vix quidem comprchendi possint. Ex repetitis tamen meis dissectionibus id pro rerte habeo, duos vel tres, quos perforantes apptllare vellem, exorin, hos truncu- lis suis ad externum latus prsecipue connYcci cumque rete v.isculoso genu jungi, nutritiant inferiorem ex iisdtm gigni.et ramos insuper nuncpauciores, nunc num«- rosiores, communicantes ad flexores Cum profunda clevari." Arvidson, p. 36. Vol. II. 2 P 298 OF THE POPLITEAL ARTERY. like all these arteries about the joints, short and stumpy ; but its branches long and slender. It passes under the flesh of the biceps : it appears again at the edge of the vastus externus : one branch plunges into the vastus externus, mounts upwards, and besides supplying the muscle, inosculates with the long descending branch of the reflexa externa; while another branch turns as direcdy downwards over the face of the outer condyle, and spreads beautifully over the side of the joint, inosculating in many net-works with the corresponding artery from below. ARTERIA ARTICULARIS SUPERIOR INTERNA. The upper articular artery of the inner side goes off in like manner over the inner condyle, pierces the tendon of the triceps, where it is implanted into the condyle, and pas- sing under the edge of the vastus internus, turns towards the fore part of the knee, proceeds towards the patella, and covers chiefly the inner side of the joint with its net-work of inoscu- lations ; its little twigs slip in under the great lateral ligament, and under the sides of the patella to the cavity of the joint itself. It inosculates like the outer artery with the lower ar- teries of its own side. > ARTERIA ARTICULARIS MEDIA. The middle or azygous articular artery usually arises from the back part of the popliteal artery, but sometimes from one or other of those last described ; but this branch, at all events, is seldom wanting. It runs down behind the main artery upon the back part of the joint, into the great hollow betwixt the condyles ; and all its branches are expended upon the back of the capsule, the posterior crucial ligament, the semilunar cartilages, and the fat about the back of the joint. LOWER ARTICULAR ARTERIES. The lower articular arteries are more slender, longer, run downwards very low, and return upwards with a very sudden angle. OF THE POPLITEAL ARTERY. 299 ARTERIA ARTICULARIS INFERIOR EXTERNA. The external articular artery below the knee goes off from the popliteal at the middle or centre of the joint, turns downwards along with the popliteal artery for a considerable way ; it passes urider the heads of the small plantar muscle and the outer head of the gastrocnemius, and having passed through, encounters the head of the fibula, and passes above it to the side of the joint, spreading its branches towards the patella. In the ham this artery gives muscular branches to the heads of the muscles, as of the gastrocnemius, solaeus, plantaris, and the popliteal muscle, that muscle which lies obliquely across the ham. When it reaches to the side of the joint, it passes tmder the external lateral ligament; and several of its branches, besides their external anastomoses, go into the cavity of the joint, one of which within the joint is especially large. ARTERIA ARTICULARIS INFERIOR INTERNA. The internal articular artery below the knee is larger than the external one. Like it, it bends downwards, passes under the inner head of the gastrocnemius muscle, crosses behind the head or rather neck of the tibia, on the inner side of the knee. It first gives arteries to the back of the joint; then it communicates downwards with a large re- current artery from the tibialis antica ; it inosculates upwards with the articularis superior interna ; it contributes (as all the other articular arteries do) to the forming of that profuse net- work of arteries which is spread over the whole of the capsule of the knee-joint. It sends also, like the others, certain twigs, which creep under the internal lateral ligament, and go into the cavity of the joint along the borders of the semilunar cartilages. . c Those who write on aneurisms of the ham talk much ot these arteries. They compare them with the recurrents of the arm ; and think, when they see five articular arteries, that it is a sure sign that at such a point all is safe ; when really these arteries cannot be of the smallest service. They are all de- stroyed by the long compression of the popliteal aneurism, or are ingulphed in the bag of the aneurism. If they ever appear, it is not as inosculating arteries, ensuring the safety of the limb ; but as small branches bursting into the sac, embarrass- soo Of THE THREE ARTERIES ing the operator, and confounding every thing, sometimes filling the sac a-new with blood, after all was thought to be quite safe, and the patient laid in bed. Before the popliteal artery passes under the head of the solaeus, it gives two long arteries, which run down upon the two heads of the gastrocnemii muscles. It often also sends small twigs to the head of the solaeus, and to the popliteal and plantar muscles. OF THE THREE ARTERIES OF THE LEG AND FOOT. The three'arteries are, the tibialis antica, going on the fore part of the leg ; the tibialis postica, passing deep" along the back part of the leg ; and the peronea, which is the smallest and least regular artery of the leg, and which has its name from passing down behind the fibula. The popliteal artery divides below the ham, under the longer head of the solaeus muscle, into two arteries, the tibia- lis antica, and tibialis postica. The tibialis postica continues its natural direction downwards under the solaeus muscle, and behind the tibia. ARTERIA TIBIALIS ANTICA. The tibialis antica makes a sudden turn forwards, per- forates the interosseous membrane just under the lower edge of the popliteal muscle ; passes out towards the fore part ofthe leg, betwixt the heads of the tibia and fibula : but still it does by no means become a superficial artery ; on the contrary7, it lies deep betwixt the heads of the tibialis anticus and the ex- tensor of the toes ; and is covered here with a very strong fas- cia. It is only about six inches above the ankle that the leg grows tendinous and naked ; there this anterior artery can be felt beating: it lies betwixt the tendons of the tibialis anticus muscle and that of the extensor of the toes ; it passes down along with these tendons, through the annular ligament, and over the bones of the tarsus ; it sends one branch across the foot, another forward to the great toe : but the artery itself dives betwixt the first and second metatarsal bone in the mid- dle of the foot, and so gets to the sole, where it ends in inos- culations with the back arteries. Of THI LEG AND FOOT. 301 There is here something like a posterior recurrent artery; *or the tibial artery, before it passes out of the ham, gives a small branch which ascends towards the back part of the joint, and is distributed to the heads of the bones, viz. the tibia and fibula, and to the origin of some of the muscles. ARTERIA RECURRENS. There is here an anterior recurrent, larger than any in the arm, and much resembling the recurrens interossea. It is a branch which comes off from the fore part of the tibial ar- tery, instantly after it has perforated the interosseous mem- brane ; it turns immediately upwards under the flesh of the tibialis anticus ; it gives many muscular branches, some to the head of the tibialis, others to the upper part of the extensor digitorum, and branches go round the head of the fibula to the origin of the long peronaeus muscle. One branch goes directly upwards, and spreads all over the lower part of the knee-joint, mixing its branches in the common vascular net- work. The tibialis antica gives no other branch of importance, or which should be named, even from the place of this recurrent quite down to the ankle-joint; for this, like the radial, or fe- moral, or any long muscular artery, continues giving off branches from either hand to the muscles betwixt which it runs, of equal size nearly, and all equally unimportant. The tibial artery, then, as it runs down the fore part of the leg, gives branches to the Tibialis Anticus on one hand ; to the Com- mon Extensor of the toes on the other hand ; and to the Ex- tensor of the great toe, which is the last of the three muscles that occupy the fore part of the leg. It also gives little arter- ies to the tibia, to the fibula, and to the interosseous membrane which lies betwixt them; but still it arrives unexhausted at the fore part of the ankle-joint. But before it crosses the joint (which it does by passing ob- liquely along with the tendon ofthe great toe), it gives out two malleolar arteries, i. e. two arteries, one to the outer, and one to the inner ankle. ARTERIA MALLEOLARIS INTERNA. The artery of the inner ankle goes off just where the head of the tibia begins to bulge. It turns over the inner ankle in many small branches ; some mounting upwards along the 302 OF THE THREE ARTERIES tibia, but more going downwards over the inner side of the joint, i. e. over the tibia or inner ankle over the astragalus, and some down as low and as far backwards as the heel-bone. ARTERIA MALLEOLARIS EXTERNA. The artery of the outer ankle goes off a little lower down. It sends smaller branches upwards round the outer ankle, which go to the Peronaeus Brevis muscle, to the joint, and to the common extensor of the toes, inosculating round the outer ankle with the fibular arteries. But its chief branch de- scends along the fore part and outer side of the foot, gives twigs to the short extensor ofthe toes, and ends in inosculations with the tarseal arteries, or arteries belonging to the fore part of the foot. The arteries which belong to the fore part of the foot arc usually three in number: one goes off from the tibial artery a litde above the ankle-joint, and is named Arteria Tarsea, be- cause it crosses the foot over the bones ofthe tarsus. To this succeeds a second about the distance of half an inch from it, and which crosses the foot at the place ofthe metatarsal bones; it is named Arteria Metatarsea : and the one or other of these gives the interosseous arteries, accordingly as the one or the other is small or wanting. The third is that remarkable branch which goes forwards along the great toe, whence it is named Arteria Halucis. ARTERIA TARSEA. The tarseal artery, which is sometimes of a very con- siderable size, admost equal to the tibialis itself, comes off a littie below the ankle, upon the fore part of the foot. It lies upon the second rank of the tarsal bones ; it passes under the head of the extensor brevis of the foot; it crosses the foot obiiquely, so as to end in the abductor muscle of the little toe, and in inosculations with the arches of the sole of the foot. This branch gives small inosculating arteries upwards, which first give branches to the joint, and then join with the external malleolar and peroneal arteries. Next it gives branch- es to the bones and joints of the tarsus, which it lies upon ; as the cuboid and cuneiform bones, and their joints. Thirdly, It gives small arteries to the bellies of the extensor brevis, where it lies under it. But its greatest arteries are the interosseous arteries, which OF THE LEG AND FOOT. 303 it sends along the interstices betwixt the metatarsal bones.— These interosseous arteries are three in number ; they run along in that interstice which holds the interosseous muscles ; and when they arrive at the end of that furrow, or, in other words, at the place ofthe forking ofthe toes, each interosseous artery turns down to the sole of the foot, and goes into the fork of each digital arch, on the lowest side of the toes. Some- times these arteries give also small dorsal arteries to the backs of the toes. The tibial artery having proceeded along the tarsal bones, and arrived at the lower heads of the metatarsal bones, and having first given off some trivial branches to the joints of the foot on its inner side, and to the bones and muscles about the root of the great toe, next gives off a metatarsal artery.* ARTERIA METATARSEA. The artery of the metatarsus or instep goes off at the head of the first metatarsal bone. It bends across the roots of the metatarsal bones to the root of the little toe ; and it distri- butes branches to the tendons of the peronaei muscles, and ends in the abductor of the little toe, and in the skin over the outer edge of the foot. But sometimes it is a larger and more important artery ; for when the tarsal artery is small or want- ing, this metatarsal one gives off the interossei, and supplies its place. DORSALIS EXTERNA HALUCIS. The third branch is the artery ofthe back ofthe great toe. This artery- is of very considerable size ; it gives no muscular branches, because it lies upon the bony part of the foot ; it runs all along the metatarsal bone which supports the great toe ; and it ends at the forking of that toe in two great branches ; one the dorsal artery of the great toe, which goes along it to the point; another to the side of the toe next the great toe, which it also runs along, somewhat like the forking arteries of the thumb and fore-finger. , . . _ The anterior tibial artery ends here (i. e. where it gives off the artery of the great toe.) By sinking in betwixt the meta- » N B Betwixt the tarsal and metatarsal artery, there is usually a small branch' going outwards to the outer edge of the foot, i. e. in the sanv direction with both these artcr:.., but very small. 304 OF THE THREE ARTERIES tarsal bones ofthe great toe and of the toe next to it, and going directly into the arches of the sole of the foot, it produces a great and important anastomosis, similar to that of the radial and ulnar arteries. ARTERIA TIBIALIS POSTICA. The posterior tibial artery is so named from its pass- ing along the back part ofthe tibia. The anterior tibial artery passes through the interosseous membrane only at the lower edge of the popliteal muscle : this artery comes off from the general trunk at the upper edge of the popliteal muscle, and passes obliquely towards the inside of the tibia, to take its place behind that bone. Its whole situation and general course is this : it lies over the tibialis posticus and flexor muscles : it lies under the bellies of the gastrocnemius and solaeus ; it turns round the inner ankle close upon the bone. Having passed the lower head ofthe tibia, it goes down along the inside of the heel-bone, in its deep arch, upon which the body is supported ; it divides at the heel-bone, and advances along the sole of the foot in two great branches; one running along the sole, next the outer edge of the foot; the other along the inner edge of the foot; whence they are named external and internal plantar arteries. From this arch the artery gives branches to all the toes, and so it ends. This posterior artery is chiefly a muscular one, at least in its course down the leg; and though it gives many branches as it passes along, there are hardly any worthy of being described : and from the knee to the ankle-joint there is one only which needs be distinguished by name, viz. the artery which nourish- es the tibia. First, The tibialis postica often gives arteries to the heads ofthe gastrocnemii muscles; next it gives off the arteria nutritia tibiae, which begins a litde below the lower edge ofthe popliteal muscle, runs downwards along the interosse- ous ligament, gives muscular branches to the popliteus, solaeus, and tibialis posticus, and then sends the nutritious artery into the great hole in the middle of the tibia. It gives many branches to the periosteum of the tibia, and to the interosseous membrane all down the leg, and it ends near the lower end of the tibia in inosculations with the peroneal artery. Other nameless muscular arteries succeed to this, going to the tibialis posticus, to the flexor communis, and to the flexor ofthe great toe. When the artery arrives near the ankle-joint, it gives many small twigs to the periosteum, tendons, sheaths, and bursae mucosae behind the ankle ; and then passing in the OF THE LEG AND FOOT. 305 very deepest part ofthe ankle, under the annular ligament, and betwixt the tibia or process of the inner ankle and the heel- bone, it adheres closely to the bones and capsule of the joint; and there gives a great many little tortuous arteries, making net-works over this joint and its bones, as over the other joints already described. But especially two delicate arteries go out at this hollow at the side of the heel-bone : one forwards to- wards the side of the ankle-joint, the other downwards and backwards over the heel-bone, which ramify very profusely and very beautifully. The artery now lying deep under the abductor magnus of the great toe, which arises from the heel-bone, forks into its two great branches, the external and internal plantar arteries, ARTERIA PLANTARIS INTERNA.. The internal plantar artery is much the smaller branch, not to be compared in importance (though their names are contrasted) with the external plantar artery ; and it is nam- ed internal, because as it runs along the sole ofthe foot it keeps to the inner edge, viz. that to which the great toe belongs. It comes off under the head of the abductor of the great toe, and under the belly of that muscle, and close upon the bone ; its branches run forwards, quite up to the root ofthe toe, all along its metatarsal bone. The internal plantar artery has in general four branches, which all run pretty nearly in the same direc- tion, viz. straight forwards. It gives, while under the head of the abductor, small branches, which go backwards to the joint, its capsule, and tendons, and some into the spongy substance of the heel-bone ; some also to the short flexor ofthe foot, and to the massa car- nea. But its four greater and more regular branches are these : The first lies nearer the inner edge of the foot; is the largest and most considerable ; it runs along under the inner border ofthe abductor ; it goes quite up to the ball of the great toe, and unites with the proper artery of the toe. As it goes along it irives small twigs to the periosteum and bone. The second resembles the former, except that it does not come off so early by two inches; it is of course shorter, but it D,sses along in the same direction, only a little distant from the first, King along the middle of the metatarsal bone. It „is0 advances up to the root ofthe great toe, and runs also in- to the proper artery of the great toe (which comes from the external plantar branch,) so as to enlarge and strengthen it. ' Vol. II. 2 Q 306 OF THE THREE ARTERIES • The third lies still nearer to the centre ofthe foot, and deep- er among the muscles. It runs the same general course, viz. along the side of the metatarsal bone up to the ball of the great toe, and ending like the others in the artery of the great toe ; but as it lies deeper, it gives branches to the short flexor, to the tendons, and to the inner surface of the aponeurosis plantaris, forming a sort of superficial arch. From these three arteries, much of the skin on the sole of the foot has its branches. The fourth and last branch of the plantaris interna, is one which goes down deep into the centre of the foot; it lies close upon those ligaments which bind together the bones of the tar- sus, and under all the tendons, except those ofthe tibial mus- cles which are like ligaments to the bones. Its destination is chiefly to the tarsal joints and capsules ; its inosculations with the external plantar artery can be of no importance. PLANTARIS EXTERNA. The external plantar artery is the great artery ofthe sole of the foot, from which the arches of the foot and the in- osculations with the anterior tibial artery are formed. It turns outwards towards the outer edge of the foot; it runs its great circle round by the metatarsal bone of the litde toe ; and its plantar arch, or the arch of the sole of the foot, passes over the middle of all the other metatarsal bones. It receives the anterior tibial artery under the middle of the me- tatarsal bone of the great toe. It is this great curve of the ar- tery turning round in the sole of the foot that we name the plantar arch ; and it is from it that all the proper arteries of- the toes arise, expressly after the same order in which the fingers receive their arteries. The great or external plantar artery lies deep, but not upon the naked bones like the former. It passes through betwixt the heads of the short flexor and massa carnea ; it turns its first turn outwards, till it gets under the flexor and abductor of the little toe ; then it turns inwards towards the centre ofthe foot, and lies under the tendons ofthe long muscles, and over the metatarsal bones and their interosseous muscles. First, it sends a large branch backwards to the heel-bone, which belongs entirely to that spongy bone, forms, like all such arteries, a sort of net-work over all the surface ofthe bone ; it first touches the bone under its extreme point, or that which rests upon the ground ; and it goes branching over it so high as to inosculate round the ankle with twigs of the tibialis anti- OF THE LEG AND FOOT. 307 ca ; it gives branches also hereabout to the great ligament of the heel-bone. The external plantar artery next gives branches to those muscles betwixt which it lies imbedded, viz. the massa carnea and flexor brevis ; then advancing to the side of the flexor digiti minimi, it gives out two or three branches, which first go into the flesh of the abductor and flexor of the little toe, and then turning over the edge of the foot, termin- ate in inosculations with the arteries of the fore part of the foot and in the skin. It then begins from the root of the metatarsal bone of the little toe to form that great circle which is named the arch of the foot, and which gives out two ranks of arteries : first, of interosseous arteries going to the spaces betwixt the me- tatarsal bones upon which the toes stand ; and, secondly, the proper arteries of the toes themselves. The first of these arteries proceeding from the tarsal arch is a small one, the artery of the little toe. It begins at the lower head of the metatarsal bone, lies under the flexor and abductor muscles, gives branches to these muscles and to the skin, and to the bone itself; it runs up the outer edge of the little toe, and this is immediately succeeded by the first inter- osseous artery ; which lies deeper, passes along the first in- terosseous space, gives branches to the bones and interosseous muscle, and inosculates betwixt the toes with the branches of of the anterior tibial artery. The next artery is properly the first of the great arch. It is what is called the ramus digitalis, or proper artery of the toes. It is a long artery, runs over the interosseous space lying upon the interosseous muscles ; it advances to the root of the little toe, and like those of the fingers divides into two branches, one to the inner side of the little toe, and the other to the side of the toe next it.—A second and a third digital artery go out in the same manner, and split at the roots of the toes into two branches, and with so litde variety that it is needless to describe each part. In the interstices of each of these arteries lie two or three small perforating arteries, which perforating betwixt the me- tatarsal bones inosculate with the interosseous arteries which lie on the fore part of the foot. But the great external plantar artery7, while it is giving out these arteries alternately, i. e. large branches to the toes, and smaller twigs to the interosseous muscles, and some smaller still which go off from the concave part of the arch, and go into the sole of the foot to the ligaments and joints ; the great artery goes still onwards, and completes its arch at the middle of that metatarsal bone which supports the great toe. There, 308 OF THE THREE ARTERIES a little behind the ball of the great toe, it receives the tibialis antica, which perforates from the fore part of the foot. This completes the arch of the anterior and posterior arteries, and permits the blood to pass, according to the pressure or other accidents, in either direction ; and this union strengthens and enlarges the artery of the plantar arch so much, that it is not exhausted by the many branches which it has given off, but gives at this point the largest artery of all, viz. the artery which supplies the great toe and one side of the toe next it. This artery of the great toe is the very last or extreme branch of the aortic system. It very closely resembles the great artery of the thumb ; it gives out three chief branches, viz. one to each side of the great toe, and one to the inner side of the toe next it. This arteria pollicis pedis sometimes seems to proceed entirely from the perforating branch of the anterior tibial artery ; at other times it arises fairly from the plantar arch. ARTERIA PERONEA. The fibular artery, or the third artery of the leg, which is much smaller than these two, is to be regarded rather as a branch of the anterior tibial artery ; and in its course and con- nections, and its being exhausted nearly by the time it reaches the ankle-joint, it greatly resembles the interosseous of the fore-arm, which stops below the wrist, or passes it only with small and extreme branches. Where the tibialis antica passes through the interosseous li- gament, the arteria peronea breaks off from it, almost of equal size with itself, and passes down behind the fibula, whence it has its name. It arises near the head or origin of the tibialis posticus muscle, and accompanies that muscle down to the ankle-joint, lying betwixt it and the flexor of the great toe. This is entirely a muscular artery for supplying those deeper parts which the other arteries do not supply. Its branches, like those of all muscular arteries, are extremely irregular; its chief branches are to the solaeus, to the peronaei muscles, to the tibialis posticus, to the flexor of the great toe. Several little arteries turn round the fibula from point to point, going to the fore part of the leg. All the way down the leg, it is giving off repeated branches to the same muscles ; and in this course it gives some little arteries, which pierce through the interosseous membrane, and also gives the nutritious artery of the -fibula. When it approaches the ankle-joint, the fibular artery gives OF THE LBG AND FOOT. 309 °ff an anterior branch, which perforates the interosseous membrane, passes through betwixt the tibia and fibula nearly where they are joined; it turns downwards over the outer side of the ankle, by the extensor pollicis and peronaeus brevis tendons. This is named peronea anterior, though it is an artery of little importance. Its branches are given not to muscles, for this is a naker Tfid bony part of the foot; but are expanded upon the lowe1- neads of the tibia and fibuJa, and upon the os cuboides. rl hey nourish the tendons, ligaments, and bursae of the outer ankle ; they end in inosculations w ith the malleolar artery, from the tibialis anterior, and with \*he tarsal artery. arteria peronea posterior. As this Anterior fibular artery branches over the fore part of the outer ankle, the posterior fibular artery pas- ses deep behind the same ankle, and is just the continuation of the main artery ; which having passed down behind the acute angle of the fibula, sinks into that deep hollow which is behind it upon the side of the heel-bone. Behind the tibia the artery makes large inosculations with the posterior tibial artery, and gives many branches to the tendons. Branches also turn round the ankle, making a net-work of vessels upon it, and inosculating with the anterior tibial artery. It continues to give the same small arteries to the outer ankle, to the peronaei tendons, to the outer side of the heel-bone, and to the abductor of the little toe. It ends usually in that muscle, and in inos- culations with that branch of the external plantar artery which turns backwards upon the heel-bone and ramifies upon it so beautifully. These are the last branches of the three great arteries of the leg and of the aortic system. END OF THE SECOND VOLUME. *.