^ ^viaosA THE ANATOMY AND PHYSIOLOGY OP CONTAINING THE ANATOMY OF THE BONES, MUSCLES, AND JOINTS, AND THE HEART AND ARTERIES, BY JOHN JELL; AND THE ANATOMY AND PHYSIOLOGY OF THE BRAIN AND NERVES, THE ORGANS OF THE SENSES/AND THE VISCERA, BY CHARLES BELL, F. R. S. E. SURGEON TO THE MIDDLESEX HOSPITAL, AND READER OP ANATOMY IN THE CHAIR OP DR. HUNTER, &C. &C. * THE THIRD AMERICAN, FROM THE FOURTH ENGLISH EDITION JN THREE VOLUMES. VOL. I. NEW-YORK: 25 <: rj HUNTED AND SOLD BT COLLINS AND CO. NO. 189, PEARL-STREET I«17. ANNEX .- THE ANATOMY OP THE HUMAN BODY, VOL. I. THE ANATOMY OF THE BONES, MUSCLES, AND JOINTS, THE HEART AND CIRCULATION, AND THE LUNGS. 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. PREFACE. >%■ those, who are at all acquainted with books on anatomy, the appearance of a new one on the sub- ject will not be surprising. To those, who are not yet acquainted with such writings, I have only to say, that I have written this book, because I be- lieved that such a one was needed, and must be use- ful. I have endeavoured to make it so plain and sim- ple as to be easily understood; I have avoided the te- dious interlarding of technical terms, (which has been too long the pride of anatomists, and the disgrace of their science,) so that it may read smoothly, com- pared with the studied harshness, and, I may say, obscurity of anatomical description. If an author may ever be allowed to compare his book with others, it must be in the mechanical part; and I may ven- ture to say, that this book is full and correct in the anatomy, free and general in the explanations, not redundant, I hope, and yet not too brief. If, in the course of this volume, I shall appear to have given a place and importance to theories far higher than they really deserve, my reader will natu- rally 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 ready to acknowledge, that I introduce To Vlll PREFACE. such theories only, as should connect the whole; and may be fairly distinguished as the physiology of acts; and he will perceive, that in this too, I feel a deference for the public opinion, and a 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 con- cerning 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, and which are the truest signs of his respect for the public, and of his care for that science to which he has devoted his 4ife. With these intentions and hopes, I offer this book to the public; and more particularly to those in whose education I have a chief concern; not with- out 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 particular task to some greater whole, is first in an author's mind: he ventures to look forward to its connection with the general science, and common course of education; or he turns it to a correspondence a»d 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 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 re-gnilar and PREFACE. iX perfect plan; and there are very few with whom a consciousness of this does not make a deep and se- rious impression at some future period, accompanied 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, following whatever is delightful, (as much is delightful,) neglecting the more severe and useful parts : but as we advance towards that period in which we are to enter upon a most difficult profes- sion, and to take our place and station in life, and when we think of the hesitation, anxiety, and appre- hension 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, unpro- fitable labour: —for there is no study which a young man enters upon with a more eager curiosity; but, not instructed in what is really useful, nor seriously impressed with the importance of his future profes- sion, 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 con- sequences, of the infinite gain or loss, which must follow the first steps in every profession, I should not feel, but, above all, I should not venture to show, 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 things, that a young man, who, by his limited fortune, or the will of his friends, by absence from his native country, or by the destination of his future life, is re- stricted to a few years of irregular, capricious, ill-di- rected 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 b \ PREFACE. 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 years, at most, his education is determined; the limited term is completed, ere he have learnt that most use- ful of all lessons—the true plan of study ; his oppor- tunities 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 profession needs to learn, this is, perhaps, the first,—that he should resist the fascinations of doctrines and hypotheses, till he have won the privi- lege of such studies by honest labour, and a faithful pursuit of real and useful knowledge. Of this know- ledge, anatomy surely forms the greatest share.— Anatomy, 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 inter- nal disease: without anatomy, the surgeon could not move one step in his great operations: and those theories could not even be 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 stu- dent. He begins with a strong conviction that this is the great study, and with an ardent desire to mas- ter all its difficulties : if he relaxes in the pursuit, it is from the difficulties of the task, and the seduction of theories too little dependent on anatomy, and too easily accessible without its help. His desire for real knowledge 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 igno- rance in that branch which is to be received as the chief test of his professional skill; or when, perhaps, PREFACE. XI he feels a more serious and manly impression, the difficulty and importance of that art which he i^ called to practise. Yet, in spite of feeling and reason, the student en- courages in himself a taste for speculations and theo- ries, the idle amusements 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 physiolo- gist, to which want of experience and a youthful fancy, have assigned a rank and importance which it does not hold in the estimation of those who should best know its weakness or strength. The rawest stu- dent, proud of his physiological knowledge, boasts of a science and a name which is modestly disclaimed by the first anatomist, and the truest physiologist of this or any age: Dr. Hunter speaks thus of his phy- siology, and of his anatomical demonstration : " Phy- " siology, as far as it is known or has been explained " by Haller, and the best of the moderns, may be u easily acquired by a student without a master, pro- " vided the student is acquainted with philosophy " and chemistry, and is an expert and ready anato- " mist; for with these qualifications he can read any L' physiological book, and understand it as fast as he " reads. " In this age, when so much has been printed up- " on the subject, there is almost as little inducement " to attend lectures upon physiology, as there would " be for gentlemen to attend lectures upon govern- " ment, or upon the history of England. 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 im- " provements 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 clearness, but study to captivate " young minds with ingenious speculation, will not Xll PREFACE. 'leave a reputation that will outlive them half a :{ century. " I always have studied, and shall continue my en- u deavours, to employ the time that is given up to ' anatomical studies as usefully to the students as I 'can possibly make it—and therefore 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 subtilty: to make a show, and ' to appear learned and ingenious in natural know- x ledge, may flatter vanity ; to know facts, to sepa- ' rate them from suppositions, to range and connect ' them, to make them plain to ordinary capacities, ' and above all, to point out the useful applications, ' is, in my opinion, much more laudable, and shall ' be the object of my ambition."* * Introductory Lecture published by Dr. Hunter Edinburgh, Sept. 1793, PREFACE TO THE FOURTH EDITION. JN giving this edition of the Anatomy of the Human Body to the public, I have been careful to revise the descriptions, and have made some additions ; so that I hope it will be found to have fewer .errors, and to present a more perfect system. Of the first part of the work by my brother, I may speak more freely. And 1 may recommend it to those who superintend the education of students, to consider whether they have not in it a work calcu- lated to open the minds of the pupils to the right understanding of the important subjects of their studies, and to give them correct and liberal views of their profession. It will not be soon surpassed in correctness and minuteness of description. I have not dared to touch the History of the Ar- teries ; the rapid improvement in the surgery of the arteries, which followed as a consequence of the first publication of this part of the Anatomy, has, with me, made it sacred. What is delivered on the com- pression of the great arteries, is an error on the safe side. I may add, that without the necessity of mak- ing experiments on so serious a subject, I have found the strength of my thumb quite sufficient to compress the main artery at the groin, both in wounds of the femoral artery, and in circumstances where I found it necessary to amputate the thigh, without the possibility of using the tourniquet. 1 must, however, acknowledge, that 1 have seen too much loss of blood from trusting to compression in XIV PREFACE. amputating at the shoulder-joint. I think, in one instance, the patient died from the loss of blood. Few assistants have strength and dexterity to accom- plish the entire compression of the artery in this operation, and such have been my fears of haemo- rrhage, that having had occasion to amputate at the shoulder-joint, in order to avoid that danger, 1 thought myself obliged to deviate from the common manner of performing the operation. On the subject of the Nerves, my reader will find an account of that system, which I have delivered in my Lectures for ten years past. That I have been so long of placing my own particular views in a systematic work, will only prove my respect for the received opinions: but the manner in which so many of my professional brethren have allowed them- selves to be assailed by new and fantastic doctrines, showing little respect for the old, makes me hesitate less in substituting opinions different from those hitherto admitted. Considerable additions have been made to the Anatomy and Physiology of the Viscera. CHARLES BELL. Soho-Sqoare, London, Jan. 1816. ©©STOH^l1© OF THE FIRST VOLUME. ANATOMY OF THE BONES, MUSCLES, AND JOINTS. BOOK I. **" OF THE BONES. CHAP. I. OF THE FORMATION AND GROWTH OF BONES, I. Page LISTORY of the Doctrines of Ossification, 2 Phenomena of ossification, ... 4 Blood Vessels and Absorbents of Bones, and Proofs of the Deposition and Re-absorption of the Bony Matter, 7 Nerves of Bones, and Proofs of the Sensibility of Bones, 11 The Process of Ossification described, . . 13 1. The various Forms, and numerous Points of Ossi- fication, ..... 14 2. The Heads and Processes of Long Bones. 3. The Cavity of Long Bones, . . 15 4. The Cancelli. 5. The Marrow. 6. The Lammellae, or Bony Plates. 7. The Holes of Bones, ... 17 8. The Vessels, . . .13 9. The Periosteum. Hi XVI. CONTENTS. Page 10. The Cartilages, . ... 20 The Callus and Regeneration of Broken Bones, . 21 CHAP. II. OF THE SKULL IN GENERAL, 24. Importance of the Anatomy of the Skull, . . 24 The Tables and Diploe of the Bones of the Skull. Enumeration and short Description of the Bones of the Cranium, ..... 26 The Sutures, ..... 27 Remarks on the Formation, Nature, and Use of Sutures, 29 CHAP. III. DESCRIPTION OF THE INDIVIDUAL BONES OF THE SKULL, 35. Os Frontis, ..... 35 1. Superciliary Ridge, ... 36 2.----------Artery and Nerve. 3. Angular Processes. 4. Nasal Process. 5. Frontal Sinuses. 6. Frontal Ridge or Spine. 7. Orbitary Process. Os Parietale, ..... 40 Os Occipitis, . . • . . .42 r. External Surface. 1. Transrerse Spines. 2. Crucial Spine. 3. Posterior Tuberosity. n. Internal Surface. 1. Greal Internal Ridge and Tentorium Ce- rebello Superextensum. 2. Hollows of the Occipital Bone. Processes of the Occipital Bone. 1. Cuneiform 2. Condyles. Holes. 1. Foramen Magnum. 2. Hole for the ninth Pair of Nerves. 3. Hole for the Cervical Vein of the Neck. 4. Common hole. Os Temporis, • • • • . 44 Squamous part. CONTENTS. xvii Page Petrous Part, .... 44 Processes. 1. Zygomatic. 2. Styloid. 3. Vaginal. 4. Mastoid or Mamillary. 5. Auditory. Holes. For the Ear. 1. Meatus Auditorius Externus. 2.----------------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, call- ed the Common Hole, as formed partly by the Temporal, partly by the Occipital Bone. 3. Small Hole on the outside of the Temporal Bone. Os CEthmoides, ..... 50 1. Cribriform Plate. 2. Crista Galli. 3. Nasal Plate, or Azygous Process. 4. Spongy Bones. 5. Orbitary PlateHor Os Planum. 6. Os Unguis. 7. Cells. Os Sphenoideb, ..... 52 Processes. 1. Alae. 2. Orbitary process. 3. Spinous process. 4. Styloid process. 5. Pterygoid processes. 6. Azygous process. 7. Clynoid processes. Anterior. Posterior. Cella Turcica, and its Cells. Holes. 1. Foramen Opticum vol. i. c XV111 CONTENTS. 2. Foramen Lacerum 3.-------Rotundum. 4. --------Ovale. 5. --------Spinale. 6. Pterygoid, or Vidian Hole. CHAP IV. BONES OF THE FACE AND JAWS, 58. Ossa Nasi, .... .58 Ossa maxillaria Scperiora, ... 59 Processes. 1. Nasal. 2. Orbitary. 3. Malar. 4. Alveolar. 5. Palate process. Antrum Maxillare, or Highmorianum. Holes. 1. Infra Orbitary. 2. Foramen Incisivum, or Anterior Pala- tine Hole. 3. Posterior Palatine Hole. Ossa Palati, . . . .64 Processes. 1. Palatal Plate or Process. Middle Palatal Suture. Transverse Palatal Suture. 2. Pterygoid .Process. 3. Nasal Plate or Process. 4. Orbitary Process. Palatine Cells. Ossa Spongiosa or Turbinata Inferiora, . 65 Vomer, ...... 66 Os Malas, . . . . ... 67 Processes. 1. Upper Orbitary. 2. Inferior Orbitary. 3. Maxillary. 4. Zygomatic. 5. Internal Orbitary. Os Maxillje Inferioris, 67 Processes. 1. Coronoid. 2. Condyloid. 3. Alveolar. Page 56 CONTENTS. XIX Page Holes, ... .70 1. Large Hole on the inner Side for the Entry of the lower Maxillary Nerve and Artery. 2. Mental Hole. CHAP. V. OF THE BONES OF THE TRUNK ; OF THE SPINE, THORAX, AND PELVIS, 70. I. Of the spine----General View of the Spine----its Motions----and the Division of the Vertebrae, 70 General Description of a Vertebra, . 71 1. Body of the Vertebra. 2. Articulating, or Oblique Processes. 8. Spinous Processes. "4. Transverse Processes. Verfebrse of the Loins, ... 73 Vertebras of the Back, ... 74 Vertebras of the Neck, ... 75 Atlas, . . . .76 Dentatus, . . , . . 78 Medullary Tube and the Passage of the Nerves, 79 Intervertebral Substance, . . 79 Motions of the Vertebrae, . . 80 II. Ribs and Sternum, . . . . 81 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. The parts of the Rib, as the Head, Neck —Surface for articulating with the Transverse Process—Nature of the Joint and Motion of the Rib—Angle of Rib, .... 82 Size and Length of the Ribs—The Car- tilages of the Ribs, . . •v . 83 ii. Of the Sternum and its three parts, . 84 III. Of the Pelvis, . .' . .86 i. Os Sacrum, ... 87 ii. Os Coccygjs, . . .89 iii. Ossa Innominata, . . 89 1. Os Ihum, or Haunch-Bone---- 1. Ala—Spine—Spinous Process- es, anterior and posterior— XX CONTENTS. Page 2. Dorsum—3. Costa—4. Linea Innominata, 90 ii. Os . Ischium, or Hip-Bone--- 1. Body—2. Tuber—3. Ra- mus, 91 iii. Os Pubis, or Share-Bone---- Body---Crest---Ramus, 92 Recapitulation of the chief Points of the Anatomy of the Pelvis, 93 Size of the Pelvis in Man and Woman, 94 Remarks on the Separation of the Bones of the Pubes during Labour. 95 CHAP. VI. BONES OF THE THIGH, LEG, AND FOOT, 98. I. Femur, - - - -98 1. Body. 2. Head. 3. Neck. 4. Trochanter major. 5. Trochanter minor. 6. Linea aspera. 7. Condyles. II. Tibia, , - - - - - 102 1. Upper Head. 2. Body. 3. Lower Head—Inner Ankle. III. Fibula, - - - . - 104 1. Upper Head. 2. Lower Head—Outer Ankle. IV. Rotula, Patella, or Knee-pan, - - 105 V. Tarsus, or Instep, - 106 1. Astragalus. 2. Os Calcis. 3. Os Naviculare. 4-} 5. } Cuneifornie Bones. 6.$ 7. Os Cuboides. VI. Toes,—Sesamoid Bones, - - - 109 VII. Metatarsus and its five Bones, - - HO CONTENTS. XXI CHAP. VII. Page BONES OF THE SHOULDER, ARM, AND HAND, 111. I. Shoulder. i. Scapula or Shoulder-blade, - 111 1. The flat Side of the Scapula. 2. The upper flat Surface. 3. The Triangular Form of the Scapu- la,—Costa—Basis. 4. The Glenoid, or Articulating Cavity. 5. The Neck. 6. The Spine. 7. The Acromion Process. 8. The Coracoid Process. ii. Clavicle, or Collar-bone, - 115 1. The Thoracic End and Joint. 2. The Outer End, and its Union with the Scapula. II. Arm. Os Humeri, - - - - J16 1. Head. 2. Neck. 3. Tuberosities. 4. Groove for the Tendon of the Biceps Muscle. 5. Ridges leading to the Condyles. 6. Condyles. 7. Articulating Surface for the Elbow- joint, and general Explanation of the Joint. 8. Hollows for the Olecranon and Coro- noid Process of the Ulna. III. Ulna and Radius, - - - - 116 I. Ulna. X. Greater Sigmoid Cavity, formed by 1. Olecranon. 2. Coronoid Process. 2. Lesser Sigmoid Cavity for receiving the Head of the Radius. 3. Ridges. 4. Lower Head of the Ulna. 5. Styloid Process of the Ulna. II. Radius, - 120 I. Bodv. XXII CONTENTS. Page 2. Upper Head, - - 120 3. Neck. 4. Point, for the Implantation of the Biceps. Flexor Cubiti. 5. Lower Plead. IV. Hand and Fingers. - 121 General Explanation of the Hand and Wrist, Carpus, Metacarpus, and Fingers. I. Carpus or Wrist, - - 122 1. Row forming the Wrist, - 123 1. Os Scaphoides. 2. Os Lunare. 3. Os Cuneiforme. 4. Os Pisiform e. 2. Row supporting the Metacarpal Bones, - - - 124 1. Trapezium. 2. Trapezoides. 3. Os Magnum. 4. OsUnciforme. • II. Metacarpus, - - - 125 III. Fingers, - - - 126 Of the Teeth, by Mr. Charles Bell, - - 127 Description of the Human Adult Teeth. 1. The Incisores. 2. The Cuspidati, or Canine Teeth. 3. The Bicuspides. 4. The Molares or Grinding Teeth. Of the first Set of the Teeth, the Milk, or Deciduous Teeth, - - - . - 130 Of the Structure of the Teeth, - - 131 Of the central bony Part of the Teeth, - 133 Of the Vascularity and Constitution of the bony Part of the Tooth, - - _ - 134 Of the Formation and Growth of the Teeth, - 138 Of the Growth of the second Set of Teeth, and the shedding of the first, - 14 j CONTENTS. XXUl BOOK II. OF THE MUSCLES. CHAP. I. MUSCLES OF THE FACE, EYE, AND EAR. Page I. Muscles of the Face, - 145 1. Occipito Frontalis. 2. Corrugator Supercilii, - 146 3. Orbicularis Oculi, or, Palpebrarum, - 147 4. Levator Palpebrae Superioris. II. Muscles of the Nose and Mouth, - - 148 5. Levator Labii Superioris, et Alse Nasi. 6.-------------------proprius. 7. Levator Anguli Oris, or, Levator Com- munis Labiorum, ... 149 8. Zygomaticus major. 9. ■---------minor. 10. Buccinator. 11. Depressor Anguli Oris, - - - f50 12. Depressor Labii Inferioris, or, Quadratus Genae. 13. Orbicularis Oris, - - - 151 14. Depressor Labii Superioris, et Alae Nasi, 152 15. Constrictor Nasi. 16. Levator Menti. III. Muscles of the External Ear. - - 152 17. Superior Auris, - - - - 153 18. Anterior Auris. 19. Posterior Auris. 20. Helicis major. 21. Helicis minor, - - - - 154 22. Tragicus. 23. Anti tragicus. 24. Transversus Auris. IV. Muscles of the Eye-ball. - 154 General Explanation of these Muscles. 25. Rectus Superior, - 155 26. Rectus Inferior. 27. Rectus Internus. . 28. Rectus Externus. 29. Obliquus Superior, - 156 30. Obliquus Inferior. XXIV CONTENTS. CHAP. II. MUSCLES OF THE LOWER JAW, THROAT, AND TONGUE. Page I»* Muscles of the Lower Jaw, - - - 157 31. Temporalis. 32. Masseter, 33. Pterygoideus Internus, or Major, - 158 34. Pterygoideus Externus, or Minor. II. MUS.CLKS OF THE ThROAT AND ToNGUE. Explanation of certain Bones and Cartilages form- ing the Basis of the Ttiroat and Tongue, and the Centre of their Motions. 1. Os Hyoides.—Its Cornua.—Its Appen- dices or perpendicular Processes. 2. Larynx, Trachea, or Windpipe* - - 159 1. Scutiform, or Thyroid Cartilage, - 160 2. Cricoid Cartilage. 3. Arytenoid Cartilages, and Rima Glottidis formed by them. 4. Epiglottis, - - - - 161 ^ Recapitulation and View of the Constitution of the Larynx. i. Muscles of the Throat. - 161 1. Muscles which pull the Throat down, - 162 34. Sterno-hyoideus. 35. Sterno-thyroideus. 36. Omo hyoideus. Action of these Muscles. 2. Muscles which move the Throat upwards. 37. Mylo-byoideus. 38. Genio-hyoideus, - - - 163 39. Stylo-hyoideus. 40. Digastricus, or Biventer Maxillae Inferio- ris. 3. Muscles moving the Parts and Cartilages of the Larynx upon each other. - 164 41. Hyo-thyroideus. 42. Crico-thyroideus. 43. Musculus Arytenoideus Transversus, 165 44. Musculus Arytenoideus Obliquus. 45. Crico Arytenoideus Posticus. 46. Crico Arytenoideus Obliquus. 47. Thyreo Arytenoideus. 4. Muscles of the Palate and Pharynx. 48. Azygos Uvulae, - - - iqq CONTENTS. XXV Page 49. Levator Palati Mollis. - - 166 50. Circumflexus Palati, or Tensor Palati Mollis. 51. Constrictor Isthmi Fauscium, - 167 52. Palato Pharyngeus. Pharynx explained. 53. Stylo-pharyngeus, - - - 168 54. Constrictor Superior. 55. Constrictor Medius. 56. Constrictor Inferior, - - 169 57. (Esophagus. 58. Vaginalis Guise. ii. Muscles of the Tongue. 59. Hyo-glossus. 60. Genio-glossus. 61. Lingualis. Motions of the Tongue performed by these Muscles. CHAP. III. OF THE MUSCLES OF THE ARM, INCLUDING THE MUS- CLES OF THE SCAPULA, ARM, FORE-ARM, AND HAND. I. Muscles of the Scapula, - - 171 i. Muscles moving the Scapula upwards and backwards. 62. Trapezius. 63. Levator Scapulae, or Levator Proprius Angularis, - - - 172 64. and 65. Rhomboides. 1. Minor, - - 173 2. Major. ii. Muscles which move the Scapula downwards and forwards. 66. Serratus Major Anticus. 67. Pectoralis Minor, - - - 174 68. Subclavius. Motions of the Scapula. II. Muscles moving the Os Humeri, or Arm-Bone. 69. Pectoralis Major, - - - 175 70. Latissimus Dorsi. 71. Deltoides, ' - - - - 176 72. Coraco-brachialis, - - - 177 73. Supra Spinatus, - - - 178 Vol. i. d XXVI CONTENTS. Page 74. Infra Spinatus, - 178 75. Teres Minor, - - - - 179 76. Teres Major. 77. Subscapularis. Motions of the Humerus, and Use and Effect of each of these Muscles in forming and strengthening the Joint, - - - 180 III. Muscles moving the Fore-arm. i. Muscles bending the Fore-arm, - - 181 78. Biceps Brachii Flexor. 79. Brachialis Internus, - 182 ii. Muscles extending the Fore-arm. 80. Triceps Extensor. 81. Anconeus, - 184 IV. Muscles situated on the Fore-arm moving the Radius, Carpus, and Fingers. Fascia of the Arm. Arrangement of these Muscles, the Points of Origin and Insertion, and the Motions of Pro- nation and Supination, Flexion and Exten- sion, explained, - 185 i. Flexors, arising from the Inner Condyle, 186 S2. Pronator Teres Radii. 83. Palmaris Longus, - - - 1S7 84. Palmaris Brevis, or Cutaneus, 18S 85. Flexor Carpi Radialis. 86. Flexor Carpi Ulnaris, - - 189 87. Flexor Digitorum Sublimis. 88. Flexor Digitorum Profundus, vel Perfo- rans, - - - - - 190 89. Lumbricales, - 191 90. Flexor Longus Pollicis, - - 192 91. Pronator Quadratus. ii. Extensors arising from the Outer Condyle, 193 92. Supinator Radii Longus. 93. Extensor Carpi Radialis Longior, - 194 94. Extensor Carpi Radialis Brevior. 95. Extensor Carpi Ulnaris, - - 195 96. Extensor Digitorum Communis. 97. Extensor Minimi Digiti, or Auricularis, 196 98. Extensor Primus Pollicis, ^ . 197 99. Extensor Secundus Pollicis, > - 198 100. Extensor Tertius Pollicis. ) 101. Indicator, - 199 102. Supinator Brevis. CONTENTS. XXV1L V. Muscles seated on the Hand. Table of these Muscles, 103. Abductor Pollicis. ^ 104. Opponens Pollicis, [ 105. Flexor Brevis Pollicis. f 106. Adductor Pollicis, J 107. Abductor Minimi Digiti 108. Flexor Parvus Minimi Digiti. 109. Adductor Minimi Digiti, 110. Abductor Indicis. 111. Interossei Interni. 112. Interossei Externi. CHAP. IV. MUSCLES OF RESPIRATION, OR OF THE RIBS. 204 General Explanation and Table of these Muscles. 113. Serratus Superior Posticus - - 205 114. Serratus Inferior Posticus. 115. Levatores Costarum, - - 206 . 116. Intercostales. 117. Triangularis Sterni, or, Sterno-costalis 207 CHAP. V. MUSCLES OF THE HEAD, NECK, AND TRUNK. 208 I. Muscles of the Head and Neck. 118. Splenius. 119. Complexus. 120. Trachelo mastoideus. - - 210 121. Rectus Minor. 122. Rectus Major. 123. Obliquus Superior, - - - 211 124. Obliquus Inferior. II. Muscles of the Trunk. 125. Quadratus Lumborum. 126. Longissimus Dorsi,» - 212 127. Sacro Lumbalis, - - - 213 128. Cervicalis Descendens. 129. Transversalis Colli, - - - 214 Arrangement of the intricate Set of Muscles filling up the Hollows and Interstices among the Spines and Processes of the Vertebra, - 21 t Pag.-! - 199 - 200 - 201 - 202 - 203 XXV111 CONTENTS. Page 130. Spinalis Cervicis, - - - 2J5 131. Spinalis Dorsi. 132 Semi-spinalis Dorsi, * - - 216 133. Multitidus Spinac. 134. Inter-spinalis Colli, Dorsi, et Lumborum, 217 135. Inter-transversales. III. Muscj.es on the fore part of the Head and Neck, completing the Catalogue of those belong- ing to the Spine. 136. Platysma Myoides. 137. Mastoideus, - - - - 218 138. Rectus Internus Capitis Major. 139. Rectus Internus Capitis Minor. 140 Rectus Capitis Lateralis. 141 Longus Colli. 142. Scaleni, - 219 CHAP. VI. OF THE MUSCLES OF THE ABDOMEN, AND OF THE DIAPHRAGM. I. Muscles of the Abdomen '** - - - 220 Importance of the Anatomy of the Abdominal Muscles, — General Explanation of these Muscles,—their Uses,—Arrangement. 143. Obliquus Externus, ... 221 144. Obliquus Internus, - 222 145 Transversalis Abdominis. 146 Recti, - - - - 223 147 Pyramidalis. Explanation of the Lines, Rings, &ic. of the Abdominal Muscles. 1. Linea Alba. 2. Linea Semilunaris, - - 224 3. Sheath for the Rectus. 4. Umbilicus. 5. Ring of the Abdominal Muscles, 225 , 148. Cremaster Muscle of the Testicle, 226 6. Ligament of the Thigh. Explanation of the different Kinds of Hernia, and the Points at which the Bowels are pro- truded. - 227 Uses of the Abdominal Muscles. CONTENTS. XXIX Page II. Diaphragm, - 227 149. The Diaphragm. 1. The Greater, or Upper Muscle of the Diaphragm, - 228 2* The Lesser Muscle of the Diaphragm. 3. The Tendon in the Centre of the Dia- phragm. Vessels perforating the Diaphragm, - 229 1. Aorta. 2. (Esophagus. 3. The Great Vena Cava. The Tendon of the Diaphragm. Uses of the Diaphragm, - - 230 CHAP. VII. HIE MUSCLES OF THE PARTS OF GENERATION, AND OF THE ANUS AND PERINEUM. General Idea of these Muscles, - 231 Structure of the Penis. 150. Erector Penis. 151. Transversalis Perinaei, - - 232 152. Accelerator. 153. Sphincter Ani, - - - 233 154. Levator Ani. 155. Musculus Coccygaeus, - - 234 Perinaeum,—the Point where All these Muscles are united. Course of the Incision in Lithotomy. CHAP. VIII. MUSCLES OF THE THIGH, LEG, AND FOOT. I. Muscles moving the Thigh-bone, - - 235 General Description of these Muscles,—Classifi- cation and Arrangement of them,—and Table of their Implantations, and of the Motions which they perform. Fascia of the Thigh, - - - 237 156. Musculus Fascialis, or, Tensor Vaginae Fe- moris, - 238 157. Psoas Magnus. 158. Psoas Parvus. 159. Iliacus Internus, - - - 239 160. Pectineus, or Pectinalis. XXX CONTENTS. Page 161. Triceps Femoris, - 240 1. Adductor Longus. 2. Adductor Brevis. 3. Adductor Magnus, - - 241 162. Obturator Externus. 163. Glutseus Maximus, - 242 164. Glutaeus Medius, or Minor. 165. Glutaeus Minimus, - 243 166. ) n . . ,«- > Gemini. 168. Pyriformis. 169. Obturator Internus, - , - - 244 170. Quadratus Femoris. Motions of the Thigh, and Action of these Muscles. II. Muscles of the Leg, - 245 Arrangement of these Muscles. *■ i. Extensors of the Leg. 171. Rectus Femoris, or, Rectus Cruris, - 246 172. Cruracus, - 247 Sub-cruraei, being Slips only of the Cru- rseus. 173. Vastus Externus. 174. Vastus Internus. Uses of these Muscles, - 248 ii. Flexors of the Leg, ... 249 175. Saitorius. 176. Gracilis, or, Rectus Internus Femoris. 177. Semitendinosus, ... 250 178. Semimembranosus. 179. Poplitaeus, - 251 180. Biceps Cruris. III. Muscles of the Foot, - 252 Arrangement. i. Extensors. 181. Gastrocnemius. 182. Soleus, - 253 183. Plantaris. 184. Peronaeus Longus, - 254 185- Peronaeus Brevis, - 255 186. Peronreus Tertius. 187. Tibialis Posticus, - 256 ii. Flexor. 188. Tibialis Anticus. IV. Muscles of the Toes, - - . 257 CONTENTS. xxxi Page 189. Flexor Longus Pollicis. - - 257 190. Flexor Longus Digitorum Pedis Perforans, 258 191. Massa Carnea J. Silvii, or, Plantae Pedis, 259 192. Flexor Brevis Digitorum. 193. Lumbricales, - 260 194. Extensor Longus Digitorum Pedis. 195. Extensor Digitorum Brevis, - - 261 196. Extensor Pollicis Proprius. Crucial Ligament, - 262 197. Abductor Pollicis. ) 198. Flexor Brevis Pollicis, > - 263 199. Adductor Poinds. ) 200. Transversalis Pedis. 201. Abductor Minimi Digiti. 202. Flexor Brevis Minimi Digiti, - - 264 203. Interossei Interni. 204. Interossei Externi. 205. Plantaris Aponeurosis. CHAP. IX. OF THE MUSCULAR POWER, 266 CHAP. X. OF THE TENDONS, LIGAMENTS, BURSJE, AND ALL THE PARTS WHICH BELONG TO THE BONES OR MUSCLES, OR WHICH ENTER INTO THE CONSTITUTION OF A JOINT. ----_ 277 General Explanation of the Tendons, Ligaments, &c. Of the Forms of the Cellular Substance, - 278 1. Its Cells, and their Use. 2. Bursae Mucosae. 3. Vagina?, or Fasciae. 4. Tendons. 5. Periosteum. 6. Vagina, or Sheaths of Tendons. 7. Capsules of the Joints. 8. Ligaments of Joints. Recapitulation and Review of the Connections of these ^ Parts, - - - - ' - - 282 Constitution and Nature of those less feeling Parts —almost insensible in Health,—slow to inflame— their Inflammation very violent, though slow—Dis- eases to which they are liable. XXXH CONTENTS. BOOK HI. OF THE JOINTS. CHAP. I. Page JOINTS OF THE HEAD AND TRUNK. 286. I. Joints of the Head and Spine. The Motions of the Head and Spine. The Provisions of these Motions. i. Joint of the Head with the Neck. 1. Articulation of the Occiput and Atlas. Form of the Joint and Capsules for the Condyles. 2. Flat membranous Ligament from the Ring of the Atlas to the Ring of the Occipi- tal Hole. - - - - 287 3. Articulation of the Atlas with the Den- tatus. Capsules betwixt the Condyles of the Vertebrae. Transverse Ligament embracing the Neck of the Tooth-like Process-—Cap- sular Ligament. Ligament betwixt the Tooth-like Process and Occipital Hole. ii. Joints of the Common Vertebrae with each other. Intervertebral Substance, and Intervertebral Ligaments. External or Anterior Vagina, or Ligament of the Spine, - 288 Internal Ligaments, - 289 Ligamenta Subflava Crurum Processuum Spinosorum—Membranae Interspinales— Ligamenta Processuum Transversorum. Posterior or Internal Ligament of the Spine. Apparatus Ligamentosus Colli. II. Joint of the Lower Jaw, - 290 III. Joints of the Ribs, - 291 Ligamenta Capitelli Costarum. Ligamentum Transversarium Externum. -------------------------Internum. Capsule and Ligaments belonging to the Cartilages. CONTENTS. xxxiii CHAP. II. JOINTS OF THE SHOULDER, ARM, AND HAND. Page I. Joints of the Clavicle, ... 292 With the Sternum. With the Scapula. II. Joint of the Shoulder, - 293 III. Joint of the Elbow, - 295 The General Capsule of the whole Joint. The Lateral Ligaments, External and Internal, - ' - - 296 The Coronary Ligament of the Ulna. Accessory Ligaments. IV. Wrist,.....297 Articulation of the Scaphoid and Lunated Bones with the Scaphoid Cavity of the Radius. Articulation of the Radius with the Ulna for the turningMotion^fthe Hand, - - 298 Articulation of tffle JJones of the Carpus with each other. -^ Articulations of the Metacarpus. Vr. Joints of the Fingers, . - - 299 CHAP III. JOINTS OF THE THIGH, LEG, AND ANKLE, 300 I. The Hip-Joint. The Ligamentum Labri Cartilaginei Transver- sale, - - - - - 301 The Capsule of the Joint. The Internal Ligaments. II. Knee Joint,.....303 1. The External Ligaments. Capsule—and Ligamentum Posticum Win- slowii. Lateral Ligaments, ... 304 Ligamentum Laterale Internum. -----------Externum Longior. ---------------------Brevior. 2. The Internal or Crucial Ligaments of the Knee, Posterior Crucial Ligament. Anterior —---------------- - 305 Vol i. e xxXiv CONTENTS. Page Semilunar, or'moveable Cartilages. - 305 Ligamentum Mucosum—and Ligamentum Alare Majus et Minus, - - - 306 Bursse Mucosa; of the Knee Joint. Recapitulation, explaining the Constitution of this Joint, and* Uses of its several Parts, - 307 III. Articulation of the Fibula with the Tibia, - 308 IV. Ankle Joint, . - - - - 309 Ligamentum Superius Anticum. -----------------Posticum. ----------Inferius Posticum. Capsule. Ligamentum Deltoides, - - 310 ----------Fibulae Anterius. ---------------Perpendiculare. ----------Inter Fibulam et Astragalum Posterius. V. Joints of the Foot. Articulations of the Rjftes of the Tarsus with each other. En Joints of the Metatarsmjjhd Toes, - 311 Aponeurosis Plantaris Pedis. Bursa? Mucosae of the Ankle and Foot, - 312 Conclusion and Enumeration of the Joints. ANATOMY . OF THE HEART AND ARTERIES. BOOK I. OF THE HEART. CHAP. I. OF THE MECHANISM OF THE HEART, 315 General View of the Circulating System, - . 3jg Of the Parts of the Heart. Venae Cava?, - ^i CONTENTS. XXXV Paec Right Sinus of the Heart, Tuberculum Loweri. Auricle, Auricular Valves. Right Ventricle, Pulmonic Artery, Sigmoid Valves, Left Auricle, Semilunar Valves of the Aorta, Aorta. Of the Coronary Vessels, Eustachian Valve, Irritability and Action of the Heart, Posture of the Heart, Pericardium, Conclusion, CHAP. II. ON THE APPEARANCE £&) PROPERTIES OF THE BLOOD, OF THE CHEMISTRi;pfcF OUR FLUIDS, AND* OF THE INFLUENCE WHICH Alft HAS UPON THEM, 355 History of Opinions concerning the Blood. Life of the Blood, ..... 36] Qualities of the Blood, .... 337 Of the Red Globules, - - - - 368 Coagulable Lymph, ... 371 Serum, - 372 General View of the Nature of the Blood. Chemistry of the Blood, .... 373 Influence of Air upon the Blood, - - - 377 1. In reddening the Blood, - - - 381 2. In communicating its stimulant Powers, - 382 3. In communicating Heat to the Body. - 3S3 Of the Respiration of Animals, ... 334 Of the Membranes of Cavities, and particularly of the Membranes of the Thorax, - - - 386 Of the Pleura, - - - - - 3S9 Of the Mediastinum, - 391 Of the Pericardium, - 394 Of the Thymus Gland, - . - - 395 Of the Lungs. Trachea and Bronchi, - - - - 396 Bronchial Cells, - 398 Course of the Blood in the Lungs, - - - 399 - 322 - 323 - 324 - 325 - 326 - 327 - 328 - 330 - 333 - 338 - 343 - 345 - 349 ft Hate M. Fig.l. Fig.3>. Fig. 4. C& rig. 7. Fig. 6. {.{"Ssr.i»r- .V. 0 Plate EL Fig. 2. Plate I. Ftg.l. TE JB ^ <&?&■■ [ ^ v.- LAft E \ ■ •' TO Fig. 3. ; EXPLANATION of THE PLATES. PLATE I. This plate illustrates the description of the manner in which ossification takes place in cartilage. Fig. 1. J. HE tibia of the foetus cut through after injection of the ar- teries. a. The body of the bone, the centre of which is soft and very vascular. bb. The cartilages, which are as yet in place of the heads of the bone. cc. Vessels seen to penetrate the cartilage from the vascular extremity of the bonaritself. i). A central nucleus of bone forming in the cartilage. ee. Vessels penetrating from perichondrium into the carti- lage : small specks of bony matter are seen to be formed by their extremities. Fig. 2 A section of the bones forming the knee joint of a child, show- ing how the apophysis is formed. \. Section of the femur, where the bone is complete. b. The cartilaginous extremity, as in fig. 1. c. A larger mass of bone formed in the cartilage, and which extending, in a short time would have occupied the place of the whole cartilage. The tract of vessels supplying the bone, and which were not visible in the cartilage, are also represented here. d. The patella, as yet a cartilage. e. The Upper extremity of the tibia, yet a cartilage. f. The bone forming in the cartilage. XXXV111 explanation of the plates. Fig. 3. Represents a section of the apophysis of a young bone; the bony nucleus separated from the cartilage by maceration. a. The cartilage. b. The bone. Explanation of Plate II. Explaining the obscure subject of necrosis, or death of a bone, and regeneration of a new one in its stead. Fig. 1. The bone of a cock's leg which was perforated, and a fea- ther introduced into the cavity of the bone—the consequence necrosis. aa. The old bone dark yellow, and not partaking of the in- jection, because, though retained in its place, dead. c. The new bone formed around the old cylinder of bone, and uniting with the end of the old bone. b. The f nd of the feather, which as a foreign body within the bo-ie, first causrd the bone to inflame and throw out new matter, and still continuing a source of irritation, killed thi: ■••■jrie. Fig. 2. Sample of the process of necrosis in the human bone. T is the thigh bone of a stump.reraaining after amputation o: ' h knee. a. Plie old bone where it was sawn through in operation. b e. The old bone seen through the interstices of the new bone. c c. The new bone inclosing the old shaft. r. The head of the bone in a natural state. The process here was similar to that in the experiment on •he rock. The wound going wrong, a bad suppuration comes upon the slump, a wasting discharge comes from within the bon«, the bone is inflamed; the disease of the marrow pro- ceeds, the bone dies, but not till new bone has been formed aound the old. During such a process it is not wonderful that the continued a ritation destroys the patient. Fie. 3. But sometimes it happens that after these injuries are sue- explanation of the plates. XXxix tained, the old bone comes away as in this example ; and the stump may yet do well. Explanation of Plate III. This plate illustrates the chapter on the formation of the teeth. Fig i. A tooth cut through and burnt. a- The enamel not affected by the heat, B. The body of the bone black. e. The canal of the tooth, in which solely the sensible nerve lies. Fig. 2. Shows the saccular pulp and rudiments of a tooth. a. The pulp of the form of the tooth hanging out of its proper place. b. The sac which contains the pulp and tooth, but being slit open they have fallen out of it. c. The shell of this bony part of the tooth which was formed on the pulp a ; but being a secretion from it, and not con- nected otherways with it, it has fallen off. Fig. 3. and 4. The rudiments of a bony part of a tooth, when beginning to form on the projecting parts of the pulp. Fig 5. A common example of a ball found in the centre of an ele- phant's tooth. a. A part of the iron ball discovered. b b. Bone formed in circles round the tooth. c. The common matter of the tooth. ©. Lesser nuclei of bone marking the irregular action of se- cretion near the ball. [Fig. 6. The bag containing the tooth and pulp, from the human subject. a. The bag, or sacculus. b. The lower part of the pulp when it can be seen without opening the sac. xl explanation of the plates. c. The sac a contains the rudiments of the milk-tooth, and here appended is already the rudiments of the second tooth. fig. 7. Section of the jaw of a child. a. The incisores of the first set of teeth. b. c. d. e. The rudiments of the eye tooth. b. The pulp, having a connection with the sacculus, and re- ceiving arteries from the bone. c. The soft pulp within the sac, and in situ. d. The connection of the sacculus with the gum. The bone of the tooth forming.—And now it will be per- ceived how it increases : how successive layers of bone are deposited by the pulp beneath; and how in due time the enamel is deposited upon the bone of the tooth by the sac which surrounds it. the ANATOMY OF THE BONES, MUSCLES, AND JOINTS. BOOK I. OF THE BONES. CHAP. I. 0F THE FORMATION AND GROWTH OF BONES.* 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 cir- cle of action and re-action in their various functions, and that intricacy 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, there is in the human body 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 what- ever 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, fitted to support, defend, and contain the more delicate and noble organs. They are the most permanent, unchangeable parts of all the body. We see them exposed to the seasons, with- out suffering the smallest change; remaining for ages the * I have arranged the preparations illustrative of the growth and structure of bone, so as to correspond with this dissertation. They form the first series in the Gallery. C. B. vol. r. A It l-> OF THE FORMATION memorials of the dead ; the evidence of a former race of meia exceeding ours in strength and stature ; the only remains of creatures which no longer exist; the proofs of such changes on our globe, as we cannot trace but by these uncertain marks. Thus we are apt to conceive, that even in the living body, \bones are hardly organized, scarcely partaking of life, not liable, like the soft parts, to disease and death. 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 full of blood as the most succulent and fleshy parts; having, like them, their periods of growth and decay; 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 exuding into the joints of gouty people, sometimes coagulated into a chalky mass. Le Dran had seen in a case of spina ventosa, or scrophulous bone, an exudation which flowed out like wax, and hardened into perfect bone Daventer had seen the juice exuding from a split in a bone, coagulate into a bony crust; and they thought it particularly wpII ascertained, that callus was but a coagulable juice, which might be seen exuding directly from the broken ends, and which gradually coagulated into hard bone. The best physiologists did not scruple to be- lieve, 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 successive conditions of a thin uncoagulated juice of a transparent cartilage, and of soft and flexible bone, became at last, by a slow coagula- tion, a firm, hard, and perfect bone, depending 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 sys- tem ; or if blood or mucus do coagulate within the body, it is only after they are separated from the system. Coagula- tion 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 pro- gress towards this perfect state, be mere inanimate, inorganized matter: yet this opinion once prevailed ; and if other theories were at that time proposed, they did not vary in any very es- AND GROWTH OF BONES: 3 s«ntial 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 animals, and, examining them at various points of time, he never failed (like other speculators) to find exactly what he desired to find. In " every experiment," he found a great effusion of blood among the muscles, and round the bro- ken bone; and he as easily traced this blood through all the stages of its progress. In the first day red and fluid ; by and by coagulated; then gradually becoming white, then carti- laginous, and at last (by the exhalation of its thinner parts) hardening into perfect bone. It is very singular, that 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 ex- periments, 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 deception that the authors of two rival doctrines arrive at opposite conclusions, by facts directly opposed to each other. Du Hamel believed, that as the bark formed the wood of a tree, adding, by a sort of secretion, successive layers to its growth, the periosteum* formed the bone at the first, renewed it when spoiled, or cut away, and, when broken, assumed the nature of bone, and repair- ed the breach. He broke the bones of pigeons, and, allowing them to heal, he found the periosteum to be the chief organ for re-producing bone. He found that the callus had no ad- hesion to the broken bone, was easily separated from the bro- ken 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 cal- lus or regenerated bone to be but a mere thickening of the periosteum, its layers being separated, and its substance swel- led. On the first days he found the periosteum thickened, in- flamed, and easily divided into many lamellae, or plates; but while the periosteum was suffering these changes, the bone was in no degree changed. On the following days, he found the tumour of the periosteum increased 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 tumour of the periosteum spongy, and divisible into regular layers, while still the ends of the bone wer un- changed, or only a little roughened by the first layer oi 'he * The periosteum k the membrane which surrounds and is attached to the eorfaee of the "seme, and which convevs the blood ve^seb to it. 4 OF THE FORMATION periosteum being already converted into earth, and deposited upon the surface of the bone : and in the next stage of its progress, he found the periosteum firmly attached to the sur- face of the callous mass. By wounding, not breaking the bones, he had a more flattering appearance still of a proof; for, having pierced them with holes, he found the holes filled op 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 of all this : That the callus, or the original bone, were in no de- gree dependent on the periosteum, but were generated from the internal vessels of the bone itself: That the periosteum did indeed appear as early as the cartilage which is to pro- duce the bone, seeming to bound the cartilage, and give it form ; but that the periosteum was at first but a loose tissue of cellular 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 vessels of the periosteum began to carry red blood, or to adhere to the bone. We know that the bones begin to form in small nuclaei, in the very centre of their cartilage, or in the very centre of the yet flex- ible callus, far from the surface, where they might be assisted by the periosteum. 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 the frac- tured bone ; or to the induration and change of the periosteum, 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 form- ing 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 record- 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, in- deed, to be broken, but without any means of being healed AND GROWTH OF BONES. 5 again; while they are, in truth, as fully organized, as permeable to the blood, as easily hurt, and as easily healed, as sensible to pain,* and as regularly changed as the softer parts are. We are not to refer the generation and growth of bone to any other part. It is not formed by that jelly 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 goes on to ripeness, by the concurring action of all its parts. The arteries, by a de- termined action, deposite the bone ; which is formed common- ly 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 se- cretion of the bony matter is performed in a distinct 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.f Any artery of the body may assume this action and deposite bone, which is formed also where it should not be, in the tendons, and in the joints, in the great ar- teries, and in their valves, in the flesh of the heart itself, or even in the soft and pulpy substance of the brain.J In the human foetus, and in other animals, before the time of birth, instead of bones, there are only cartilages of the form of the future bone. The whole foetus appears to the eye like a mere jelly : the bones are a pure, almost transparent, and tremulous jelly ; they are flexible, so that a long bone can be bended into a complete ring; and no opacity nor spot of ossification is seen. This cartilage never is 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 dilate; and when- ever 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 jelly, 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 * The obscurity on this subject is from the neglect of defined terms. We shall present- ly see that the sensibility possessed by the bones, and the kind of pain to which they are subject, differs from the sensibility ana pain of the skin and soft parts. C. B. t The bone of the tooth is formed in a manner very different from common bone. C. B. \ The structure of the true and natural bone is different from the preternatural bo»» ^■crttions m the vessels and membranes. 4\ B. e OF THE FORMATION 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 easil) known by its gritty feel. Other points of ossi- fication are successively formed ; always the ossification is fore- told by the spreading of the artery, and by the arrival of red blood. Every point of ossification has its little arteries, and each ossilying nucleus has so little dependence on the carti- lage in which it is formed, that it is held to it by vessels 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 is advanced. W'hen os- sification 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. WThen the bony matter be- gins to accumulate, the red colour of those arteries is obscur- ed, the centre of the bone becomes yellow or white, and the colour removes 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 ef&es of the first circle, the vessels are more scattered and asunder, distinct trunks are easily seen, forming a circle of radiated arteries, which point towards the heads of the bone. Beyond that, again, the cartilage is transparent and pure, as 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 various 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 sparse, form a vascular zone, and the zone at either end is transparent or white.* The ossification follows the vessels, * It is curious to observe how completely vascular the bone of a chicken is before the essification have fairly hegun ; how the ossification being begun, overtakes the arteries, and hide-- them, changing; the transparent and vascular part of the bone into an opaque white; how, by pealing off the periosieum, bloody dots are seen, which show a living con- nection 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 ; and the most beautifid proof of all is that of our i-ommon preparations, where, by filling with injection the arteries of an adult bone, by its nutritious vessels, and then corroding the hone with mineral acids, we dissolve the earth, leaving nothing but the transparent jef ly, which restores it to its or ginal cartilaginous state; and then the vessels appear in such profusion, that the bone may he compared in vascularity with the soft parts, and it is seen th * its arteries were not annihilated, but its high vascularity only concealed by the depo- sition of the bony part. AND GROWTH OF BONES. 7 a»d buries and hides 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 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 extremi- ties 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. Tbus the heads and the body are, at the first, distinct bones formed apart, join- ed by a cartilage, and 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 artery piling it up on either side to form its ridge f The body of the bone is supplied by its own vessels; the heads of the bone are in part supplied by the extremities of the same trunks which perforate the dividing cartilage like a sieve; the periosteum adhering more firmly to the heads of the bone brings assist- ant arteries from without, which meet the internal trunks, and assist the ossification; which, with every help, is not accom- plished 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 respective 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 pwn system. Every animal system, as it grow?, assimilates its food, and converts it to the animal nature, and so increases the quantity of its red blood : and as the red blood is tbus pre- pared by the actions of the greater system, the actions of par- ticular 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; * The arteries of a bone branch with freedom, and with the same seeming irregularity a.i in other parts of the body. The arteries do not exu te tiseir secretion from tVir sides, so as to pile up the ridge of bone in their course. The secretion seems to be performed in their very extremities. C. B. 8 OF THE FORMATION others again to perform certain offices within the body, as semen, saliva, bile, or urine. Thus the body is furnished with various apparatus for performing various offices, and for re- pairing the waste. These are the secretions, and the forma- tion 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 apparatus of surrounding mem- branes, its heads, its processes, and its connection with the soft parts. The colourless arteries of this pellucid but organized mass of cartilage keep it in growth, extend, and yet preserve its form, and gradually enlarging 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 themselves 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 super- fluous 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 ab- sorbents to take up the cartilage, and make room for the osseous 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, ulcerate, to rot and spoil, to become brittle 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 properties of bone, is dead, inorganized, and lies in the interstices of the bone, where it is made up 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 in 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 jelly, then radiated vessels, then ossifying spots, and these * FrevioMs to the formation of bone (or the preparation for it) in the cartilaee there is no proof of there being vessels in it But we presume that the cartilage must have vessels. because it grows with the growth of the animal, previous to the formation of bone in it However, the change, previous to the deposition of bone, has not been noticed- the firm cartilage suffers a change; there is a tract from the circumference to the centre of it in winch the firm cartilage is dissolved; and in the spot where the first particle of bone is to be deposited^ there is a little .oft well of matter, different from the firm substance of the AND GROWTH OF BONES. 9 running together, form a perfect bone.* If the broken limb be too much moved during the cure, then are the secreting ar- teries interupted in their office, perfect bone is never formed, it remains a cartilage, and an unnatural joint is produced; the vessels are opened again, the process is renewed, and the bones unite ; or even by rubbing, by stimulating, by< merely cutting the surrounding parts, the vessels are made active, and their secretion is renewed. During all the process of ossification, the absorbents proportion their action to the sti- mulus which is applied to them ; they carry away the serous fluid, when jelly is to take its place; they remove the jelly, as the bone is laid ; they continue removing the bony particles also, which (as in a circle) the arteries continually renew. Nothing can be more curious than this continual renovation and change of parts, even in the hardest bones. We are accustomed to say of the whole body, that it is daily changed; that the older 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 certain 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 unchanged; no tint remaining in the liga- ments nor cartilages, membranes, vessels, nor nerves, not even in the delicate vessels of the eye. It was easy to distin- guish by the microscope, that such colour was mixed with the bony matter, resided in the interstices only, but did not remain in the vessels 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 sudden 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 mad- * The matter may be thus stated : the extravasated blood being absorbed, an effusion is poured out by the vessels of the broken bone. This matter is a regular secretion, it ap- pears to the eye like a uniform jelly ; but so does the embryo itself. It is bone in embryo, the membranes and vessels, arteries, veins, and absorbents are in it; the arteries of the sur- rounding parts do not shoot into it, but veins, as well as arteries and absorbents, inosculate with the vessels of this new formed matter; and whatever vessels may, by accidental con- tact, inosculate with this substance, whether coming from bone, muscles, or membrane, ■till bone is formed, because it is the destined constitution of the new formed mass, or r.thei qf the vessels which arc alreadv in it to form bone. C. R. B 10 OF THE FORMATION. der 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 in the hands of Du Hamel, for proving by demon- stration, that it was by layers fr»m 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. Du Hamel, believing that the periosteum deposi- ted successive layers, which were added to the bone, it was his business to prove that the successive layers would be de- posited alternately red, white, and red again, by giving a young animal madder, withholding it for a little while, and then beginning again to give it. Now, it is easy to forsee that this tinging of the lamellae should correspond with the succes- sive times in which the periosteum is able to deposite the lay- ers 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 be laid above it, nor for a layer of red above that again, so that he should have been able to show successive layers : And if madder can so penetrate 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 proceed- ed to give madder for tinging a third layer, it would pervade all the bone, tinge the layer below, and reduce the whole into one tint. If a bone should increase by layers, thick enough to be visible, and of a distinct tint, and such layers be conti- nually accumulated upon each other every week, what kind of a bone should this grow, to ? Yet such is the fascinating na- ture of a theory, that Du Hamel, unmindful of any interrup- tions like those, describes boldly his successive layers, carry- ing us through regular details, experiment after experiment, till at last he brings up his report to the amount of five succes- sive layers, viz. two red layers, and three white ones. And in one experiment he makes the tinge of the madder continue in the bones for six months, forming successive layers oi" red and white, although in an earlier experiment (which he must have forgotten in his burr)) 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 not many 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 must question our own judg- AND GROWTH OF BONES. 11 ment, when trying to confirm our preconceived theories by experiments and facts.* Yet, by these experiments with madder, one most impor- tant fact is proved to us; that the arteries and absorbents, acting in concert, alternately deposite and re-absorb the earthy paiticles, 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, destroys 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 entirely 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; 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 is crooked; the pelvis distorted ; the breast 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 as to be cut with the knife.f 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 nutritious vessels; and yet we dare hardly believe the demon- stration, since bones seem quite insensible and dead : We have no pain when the periosteum is rasped and scraped from * However just this criticism is upon the reasoning of Du Hamel, yet I believe in the facts stated. In my Collection may be seen the bom; of a pig showing three distinct layers, distinguishable in colour. C. B. + See the examples of distortion in the Museum, Windmill Street, and in particular the skeleten of a woman who died in consequence of the Casarean operation. C. B 12 OF THE FORMATION a bone : We have no feeling when bones are cut in amputa- tion ; or when, in a broken limb, we cut off with pincers, the protruding end of a bone: We feel no pain when a bone is trepanned, 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 than to excite a par- ticular titiliation and heat, rather pleasant than painful, run- ning 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 explained. A bone may feel acutely and yet not send its sensation to the brain. It is not fit that parts should feel in this sense, which are so con- tinually 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, liga- mints, 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, except in the absence of pain, 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 will heal; or cut a piece of it away, and more bone will readily be produced ; hurt it 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 to the proof. In short, these parts have a sensibility which belongs to them- selves, but have no feelings in correspondence with the gene- ral 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, suppu- ration, ulcer, and the death and discharge of the diseased bone ensue. When the texture of a bone is thus loosened by in- flammation, its feeling is roused; and the hidden sensibility * From the consideration of these facts, together with this most essential one, viz. that bones, ligaments, and tendons are actually capable of receiving and propagating painful im- pressions to the sensonum, 1 have come to the following conclusion:—The sensation of pain is bestowed as a safeguard to the frame, forcing us to avoid whatever is hurtful To this effect, sensibility vanes in different parts, and in general the sensibility of the more superfi- cial, parts, being sufficient protection to the parts Vneath, the deep parts are but little sensi- ble. • Ihe sensibility possessed by the skin would uot he sufficient protection to the eve- such parts differ in kind of sensibility as well as in degree. Experiments have been made by cutting and burning the bones and tendons, and the conclusion has been, that they were insensible But when a man sprains his ankle-joint, he is in extreme pain, though he can easily satisfy himself that the pain he feels is not in the skin, but must be in the ioint and tendons. It appears then, that such parts usually thought insensible, feel pain and can pro- pagate that nam to the sensonum; and further, that the peculiar sensibilities are so suited as to allow of the free and natural motion and of the necessary degree of attrition, but are be- stowed for the purpose of making us avoid that degree of violence, which would e ndano-m- the texture or healthy function Sf the part. C. B. ^ endangei AND GROWTH OF BONES. 1.3 of the bone rises up like a new property of its nature : and as the eye, the skin, and all feeling parts have their sensibility in- creased by disease, the bones, ligaments, bursa:, 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 raised to a dreadful degree : the patient cries out with anguish. No pains are equal to those which belong to the bones and joints. This ossification is a process of a truly animal nature : no coagulation will harden cartilage into bone ; no change of con- sistence will form 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 is a regularly organized part, whose form subsists from the first, which is perfected by its secreting arteries, balanced, as in every secretion, by the absorbents of the part; it lives, grows, and feels, is liable to accidents, and subject to disease. Ossification is a process which, at first, appears so rapid, that we should expect it te 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 till the twentieth year; it is forwarded by health and strength, retard- ed by weakness and disease. In scrophula it is imperfect; and so children become rickety, when the bones soften and swell at their heads, and bend under the weight of the body. And why should we be surprised, that carelessness of food or clothing, bad air, or languid health, should cause that dread- ful disease, when more or less heat, during the incubation of a chick, prevents the growth of its bones; when the sickness of a creature, during our experiments, protracts the growth of callus ; when, in the accidents of pregnancy, of profuse suppu- ration, or of languid health, the knitting of broken bones is delayed, or prevented quite ? This process, so difficult and slow, is assisted by every pro- vision of nature. The progress of the whole is slow, that so 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, and others hasten- ed, as the pelvis, that it may acquire its perfect size early in life. Ossification is assisted by the softness of the cartilagi- nous bed in which the bone is formed; by those large and per- meable vessels which carry easily the grosser parts of the blood ; by a quick and powerful absorption, which all along 14 OF THE FORMATION is modelling the bone; and, most of all, by being formed in detached points, multiplied and crowded together, 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 stretches 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 interposed, which grows gradually thinner till the twentieth year, and then disappears, the body, heads, and processes, be- coming 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 meet the edges of the next bone. See plate I. fig. 3 and 4. The thick round bones which form the wrist and foot, have one ossification in their centre, which is bounded by cartilage all round. The processes are often distinct ossifications joined to the bones, like their heads, and slowly consolidated with them into firm bones f W'hile the bone is forming, various parts, essential to its sys- tem, 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 jelly, 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 * The ossification of the flat bones is a subject too curious to be omitted in this disserta- tion _ The brain of the foetus while of the size of a hazle-nut is invested with a membrane in which there is as yet no speck of hone. In the third month, the ossification of the cra- nial bones commence, and the first process exhibits a very beautiful net of ossific wire-work. In a circle, the diameter of which is half an inch, we see a perfect net-work, resembling a fine lace or the meshes of a spider's web. Upon this first layer another is deposited, and thi« superimpo»ed net-work of bone is finer than the first; the meshes being smaller and the bony matter more abundant. The holes of the second net are not opposite to those of the first, so that the eye no longer penetrates the bone, although the structure be quite light and porous. While the second and third layer of bone is deposited on the outside of the first, the inner layer is extending in threads diverging from the centre, betwixt which deli- cate processes of hone, intervening ribs are formed irregularly, still resembling the texture of the spider's web; and the diverging line of bone being the stronger, it appears as if the cra- nial bones formed in diverging radii, while the edge of the bone extends in fine net work, like to the first formed speck of ossification. It is further worthy of remark, that this is the texture of true bone, and that what are called morbid ossifications, as of the coats of arteries and other membranes are merely the deposite of earthy matter without organic structure. C. B. T The processes and heads are named the epiphysis and apophysis of bones. The apophy- sis a process which projects from the bone and grows from it. The epiphysis is that por- tion which growing by a distinct centre of ossification is afterwards united to the bodv ©f the bone. - C. B. AND GROWTH OF BONES. 15 stretch towards either end, and stop there (fig. 1. plate I.); 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 annihilated, and only a small plate remains, separa- ting 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 heads are cartiliginous; 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 con- tinue three distinct bones, during all the early part of life, and are easily separated, by soaking the bone in water; when they are separated, there is seen a rough hollow, on the sur- face of the epiphysis, or separated head, and a rough convexi- ty on the end of the body: they are finally united into one bone, about the twentieth year. In the original cartilage, there is no hollow nor cavity ; it is all one solid mass. Fig. 1. pfcite II. When the ossification first appears, the cavity of the bone also begins, and extends with the ossification : at %*st 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 with an internal membrane, containing the trunks and branchings 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 of successive ossifications of the periosteum forming the bone. These lamella?, or plates, are more condensed and firm, towards the outer surface, and are more loose, separate and spongy, to- wards the internal surface oi 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 thick, and having all their bony plates; the cells of net-work few7, and large ; but towards the ends, the bone swells out, the cavity air o is large; but it is not like that in the middle, a large tubular / 16 OF THE FORMATION 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 lattice-work, leaving only a thin outward shell.* This reticular form is what anatomists call the cancelli, lattice-work, net-work, or alveolar part of the bone : it is all lined 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 dense oil, or marrow in the adult. The mar- row is firmer, and more perfect in the middle of the bone," and more thin and serous towards the spongy ends. The whole mass, when shaken out of the bone, is like a bunch of grapes, each hanging by its statfr;. The globules, when seen with the microscope, are neat, round, and white, resembling small pearls, and each stalk is seen ty be a small artery, which comes along the membrane 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 pecu- liar cell. To this, an old anatomist added, that they had their contractile power, like the urinary bladder, for expel- ling 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 peculiarity 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 demonstrated by a careful picking, and separation of the scales in a young bone, or by burning a bone, which melts and consumes its jelly, 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, * That it is merely an expansion of the layers which forms the cancelli, and a mere swell- ing and sponginess of the same quantity of bony substance, which make* the ends so much thicker than the middle, is proved by this, that an inch of the smaller bony tube, cut from f he middle, weighs equally with an inch of the large spongy tube, cut out from the ends. AND GROWTH OF BONES. 17 while another is entire and sound. Malphighi had first ob- served the lamellated structure of bones, likening them to the leaves of a book. Gagliardi, who, like Hippocrates, went among the burial places of the city, to observe the bones there, found in a tomb, where the bones had been long ex- posed, a skull, the os frontis of which he could dissect into mary layers, with the point of a pin.* He afterwards fou' d varous bones, from all parts of the body, thus decomposed ; and he added to the doctrine of plates, that they were held together by minute processes, which, going from plate to p.'ate, 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.f Another notable discovery, was the use of the holes which are very easily seen through the substance of bones, and among their plates. They\re, indeed, no more than the ways by which the vessels pass into the bones; but the older anatomists imagined therl to be still more important, allow- ing the matter 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 of fomentations 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 moisture can reach them from without: the bone is already fully wa- tered with arteries; it is moist in itself, and cannot be further moistened nor lubricated, unless by a fuller and quicker cir- culation of its blood. It must be preserved by that moisture only which exists in its substance, and must depend for its consistence upon its own constitution; upon the due mixing up of its gluten and earth. Everv 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 moist- ness of a bone, than for preventing brittleness in the eye.— * Notwithstanding what is here delivered, there is no proof of the bones being lamella- ted ; as to the exfoliation of bone, the dead portion is more generally irregular in its thick- ness, and rugged on its inner surface. This exfoliation of bone is a process, of the living bone, and the inner living surface recedes from the outer one, because that outer surface is injured or dead. The nature of the injury, or the depth to which the bone has become dead, determines the extent and form of the portion cast off. When a scale only is thrown off, it is because the bone is only dead upon the surface. In regard to the breaking up of the surface of th% cranial bones, when they lie exposed, the scales are similar to those from stones or metals exposed to the influence of the air, and moisture, and varying temperature: the thickness and succession of exfoliations depends on the operation of the weather, not on the original formation of the bone. 1 have never seen heat produce a lamellated decompo- sition of bone. C. B. t These nails Gagliardi imagined were no more than the little irregularities, risings, and 'lollows of the adjoining plates, by which they are connected. VOL. I. C 18 OF THE FORMATION This marrow is, perhaps, more an accidental deposition than we, at first sight, believe. We indeed find in it such a regu- larity of structure, as seems to indicate some very particular use ; but we find the same structure exactly in the common fat of the body. When, as we advance in years, more fat is deposited in the omentum, or round the heart, we cannot entertain the absurd notion, of fat being needed in our old age, to lubricate the bowels or the heart; no more is the mar- row (which is not found in the child,) accumulated in old age, forpreventing brittleness of the bones.* 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 it is called the nutritious or medullary artery : it goes in the central cavity of the bone, spreads upwards and down- wards, supplies all the substance of the bone itself, and gives those delicate arteries which secrete the marrow. Other arte- ries enter from without at the spongy ends of the bones, where the bones are not visible only, but very large in the adult; par- ticularly large arteries enter into the heads of the holes, 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 jbiefuse of that membrane ;) so that in tearing off the periostefmi, the surface of the membrane, and of the bone, are seen covered with bloody points; all the vessels are conducted to the substance of the bone by its two membranes: the internal vessels by the membrane which lines the cavity, and which is known b\ the absurd name of inter- nal periosteum ; the external one by the outer membrane, the proper or external periosteum. The interna] periosteum is that membrane which surrounds the marrow, and in the bags of which 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 con- nection and office is so essential to the life and health of the .. bone, that the spina ventosa, or scrophulous bone, is merely a * If we look to the difference there is in the adipose membrane, we shall find it more apparent than real. The fat on the soles of the feet and palms of the hands is particularly firm, but this firmness results from the strong intertexture of filaments of a tendinous strength. The fat in the exposed parts of the limbs is less firm, in the orbits of the eyes more delicate, but in the bones it lies in transparent membranes, and is quite soft and compressible. The difference, however, is only in the manner in which the bags containing the fat are bound up and protected ; where the substance is exposed to pressure, it is firm • where it lies concealed, it is less so; but where it is altogether within the protection of the bones, the membranes are very delicate, and the fat takes the appearance of marrow. C. B. AND GROWTH OF BONES. 19 failure of the internal circulation, a total corruption of the mar- row, and a consequent loss of the medullary vessels; by which the whole bone dies, is thrown out by nature, or oftener the limb must be cut off.* The same effect is produced in our experiments, where, by piercing into the medullary cavity, and destroying the marrow, the shaft of the bone dies, while the heads and processes live, only because they are supplied more fully by their external vessels. % -The periosteum, which was once referred to the dura ma- ftr, is merely condensed cellular substance ; of which kind of tnatter we now trace many varied forms and uses, for so close is the connection of the periosteum, tendons, ligaments, fascia?, and bursa:, 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 con- densed one above another: it adheres to the body of the bone by small points or processes, which dive into the substance of the outer layer, giving a firm adhesion to it, so as to bear the pulling of the great tendons, which are fixed rather into the periosteum than into the bone. It is also connected with the bone by innumerable vessels. The layers of the periosteum fnearestto the bone are condensed and strong, and take a strong 0 adhesion .to the bone, that the vessels may be transmitted safe, mid the fibres of this inner layer follow the longitudinal direc- tions of the bony fibres. The periosteum is looser in its tex- ture outwardly, where it is reticulated and lax, changing im- perceptibly into the common cellular substance. There the fibres of the periosteum assume the directions of the muscles, tendons, or other parts which run over it. The periosteum is not for generating bone ; and therefore it adheres but slight- ly to the growing bone : it is for nourishing the external plates; and therefore, as the bone grows, and as the external 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 medulla kills the whole bone, hurting the periosteum kills the outer layers of the bone. Any accident which spoils the bone of its peri- osteum has this effect; the accidental wounds of the peri- osteum, deep ulcers of the soft parts, as on the shin, the beat- ing of aneurisms, the growth of tumours, the pressure even of * This disease is rather what we call necrosis, in which the bone dies. _ The spina ven- tosa is the consequence of abscess iu the cavity of the bouc. See the specimens in my col- lection. C. B. 20 OF THE FORMATION any external body, will, by hurting the periosteum, cause ex- foliation, which is, in plain terms, the death of the external layer, by the injury of the outward vessels; and an active in- flammation of the 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 a 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 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 pro- duced in the instant in which they appear: they had existed before ; they are but dilated now; the increasing action di- lates them, and the dilatation makes them red ; this enables them to secrete bone, and, in many cases, as in the accidental 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.f * It is the injury to the surface of the bone which causes the exfoliation, not the loss of vessels by the separation of the periosteum; and when the bone dies, as in necrosis, lroni the injury to the marrow, inflamation precedes the death. C. B. •J- This is true as a physiological fact, but it is not the proper method of curing this de- fect of union in a bone. See the 2d vol. of'Operative Surgery by Charles Bell. -J* AND GROWTH OF BONES. 21 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, main- tained 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 humours 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 obscure, 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 re- moved ; to bear all the shocks of leaps or falls ; to perform all the motions of the body, and the continual workings of the joints, where they rub, and even crackle upon each other with- out danger or pain. We now understand the constitution of a bone, and can com- pare it fairly with the soft parts in vascularity, and in feeling; in quickness of absorption; in the regular supply of 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 ar- teries 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 bo- ny matter, that the composition may neither be too brittle nor too soft. From this constitution of a bone, we could 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 gelati- nous 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 ani- mated by vessels coming into it from every point. In every external wound, in every internal inflammation, wherever ex- ternal parts are to be healed, or interna] viscera are about to adh< re, 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, ad- 22 OF THE FORMATION here by inflammation to the coats which surround them, and which are naturally loose. It is a miicus of the same form which unites the ends of a broken bone; and, by breaking the bones of animals, and attending to the progress of the callus, we find first a thin mucus ; then that thickened into a transpa- rent jelly; that jelly growing vascular, and these vessels gradu- ally depositing nuclsei of ossification in the centre of the mass; and by madder or by fine injections, we can make the jelly appear vascular, and make the nuclaei of ossification quite red. The colours of our injections begin to tinge the cartilage as it begins to ossify, and as soon as the ossification is general, it receives a general tinge. When we find the substance of the oldest bone thus full of vessels, why should we doubt its being able, from its own pe- culiar 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 bone; and each part of this system is of itself capable of regenerating the whole. How little the constitution of a bone has been under- stood, we may know from the strange debates which have subsisted so long about the proper organ for generating 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 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 was formed surrounding a carious one, and the spoil- ed 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 only. But presently another ana- tomist 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 remain sound, or must have been secreted by the medullary vessels. But the truth is, that callus 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 de- * The term, system of a bone, is incorrect, if by it is meant the periosteum which sur rounds the bone, and the marrow within. In the experiments and observations which I have made, ueither the periosteum or marrow seemed to have formed the bone; and I con- clude, that nothing but bone can form bone, by the contiuuation of natural actions; and that "iii the cuse of necrosis, the old bone inflames and begins the new formation, before the continued irritation in the centre kills it. C. B. AND GROWTH OF BONES. 23 stroy the marrow, the old bone dies, and a new one is formed from the periosteum : ff we kill the creature early, we find the new bone to be a mere secretion from the inner surface of the periosteum ; and if we wait the completion 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 ope- ration, 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 quite black and dead, surrounds it;* and in fractures of the patella or knee-pan, where there are no medullary vessels, 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 they 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. * When I injure the marrow of the bone, necrosis is the consequence, see plate III. tig. 1. When I divide the bone of its periosteum and surround it with a bit of bladder, I find the whole surface exfoliates, and the cavity of the bone fills up ; but this is not a con- sequence of the destruction of the vessels of the periosteum,but of the contact of foreign matter with the surface of the bone. An effect precisely similar is the consequence of the slough- ing of the soft parts over a bone, for the dead slough lying on the surface of the bone causes an exfoliation. The effect of injury to a living bone is very curious. But the manner in which the bone resumes its pristine form is still more worthy of observation. At first the outward exfolia- tion is attended with a proportionate filling up of the cavity of the bone. And the injury to the centre and body of the bone produces a new bone around the old one, and the old one at last dies and is absorbed or discharged. But after years these changes are again reversed, and the new bone contracts its diameter, and the cavity becomes of its uatural dimentions, so that the evidence of the changes which the bone has undergone are quite removed. This is a very beautiful example of the influence of that principle which controls the growth of all the parte of the body, which may have its operation deranged by violent injury or by disease; but which will at last by slow degrees restore the part to its natural form and action. C. B. ( 24 ) CHAP. II. OF THE SKULL IN GENERAL--THE BONES OF WHICH IT 13 COMPOSED--THEIR TABLES--DIPLOE--SUTURES--THEIR ORIGINAL CONDITION, AND THEIR PERFECT FORM, REPRE- SENTED AND EXPLAINED. W HILE the bones in general serve as a basis for the soft parts, and supporting and directing the motions of the. body, certain bones have a higher use in containing those organs whose offices are the most essential to life The skull de- fends 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 diffi- cult a study* as this anatomy of the head; and if this fatiguing study can be at all relieved, it must be by first establishing 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 bones, 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 spongy, less easily broken; the inner ta- OF THE S^KULL IN GBNERAL. 25 ble, 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 caneclli, 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 ves- sels 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 pericra- nium, which had been sound and unhurt; and every disease of the cancelli, or substance of the bone, is communicated both ways; inward to the brain, so as to occasion very imminent danger; outwards 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 intermediate 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 ex- ternal table ; when we arrive at the cancelli, there is less re- sistance, 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. Sur- geons 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 indiscreet hurry, and unpardonable rashness in operation. The patient, during this sawing of the skull, is suffering neither danger nor pain :f and many additional rea- sons lead us to refuse altogether this rule of practice : for the skull of a child consists properly of one table only: or tables are not yet distinguished, nor the cancelli formed : in youth, the skull has its proper arrangement of cancelli and ta- * 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, o» twelfth of an inch, is a measure which I shall often have occasion to use. t There is a state of inflammation, either under the dead bone or in the surrounding bone, * hich gives extreme pain, even when the silver probe touches the dead bone. C. B. 26 OF THE SKULL IN GENERAL. bles; but still, with such irregularities, and exceptions, as make a hurried operation unsafe : in old age,.the skull declines to- wards its original condition, the cancelli are obliterated, the ta- bles approach 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 life in which this operation may be per- formed quickly and safely at once. But, besides this gradual progress of a bone increasing in thickness and regularity, as life advances, and growing irregular and thinner in the decline of life, we find dangerous irregularities, even in younger skulls. There are often at uncertain distances, upon the internal sur- face of the skull, hollows and defects of the internal table, deep pits, or fovea:, as they are called, produced, perhaps, by the impressions of contorted veins. These fovea? increase in size and in number, as we decline in life : they are more fre- quent 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. The BONES of the skull are divided into those of the cranium ; the bones of the face ; and common, or interme- diate bones.* * The head is divided into the cranium and face. For the cranium we find in old authon the words calva or calvaria imp calvis, bald, or sometimes cerebri galea, as being like a helmet to protect the brain. We find some terms distinguishing certain parts of the cranium as glabella, the smooth part in the centre and lower part of the forehead. Occiput, the utmost convexity of the head harkwaid. Vertex, the crown of the head where the hairs turn. Bregma, or/on- tanelk, which are terms derived from very false notions, but which mean the interstices' left in a cuild's skull betwixt the cranial bones. Tie student ought to know these terms, hut good taste rejects them even from medical language, when the description can be given in plain English. The following is the usual division of the bones of the head. In the adult head there are thirty bones and thirty-two teeth. Of the Cranium, Intermediate or Bonks of the Fack, Six Pones. Common Pones. Two. Fourteen. 1 Os Frontis 1 Os Sphenoides 2 Ossa Maxillaria Supra. 2 Ossa Parietalia 1 Os Ethmoides 2 Ossa Malarum 2 Ossa Temporalis 2 Ossa Nasi 1 Os Occipitis 2 Ossa Palati 2 Ossa Unguis 2 Ossa Turbinata Infa 1 Vomer 1 Ossa Maxillaria Infp Bones of the Ear, Teeth, Thirty-two. Foi'r on each Side. Maleus 8 Incisores Incus 4 Cuspidati Os Orbiculare 8 Bicuspides Stapes 12 Molares 32 OF THE SKULL IN GENERAL. 27 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 occTpitis, 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 jethmoides, and, 6. the os sphemhdes, are quite hidden in the basis of the skull: they are very irre- gular and very difficultly described or explained. The os ath- moioks, is a small square bone, hollow, and with manj cells in it: it hangs over the nose, and constitutes a great and im- portant part of that organ, and at the same time supports the * brain. The olfactory nerves, by passing through it at many points, perforate it like a sieve; and it takes its name from this perforated or athmoid plate. The os ^phenoihes is larger and more irregular still; placed further back; locked in betwixt the occipital and sethmoidal bones; lies over the top of the throat, so that its processes form the back of the nostrils, and roof of the mouth ; and itjs so placed, as to sup- port 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 na- med sutures.* * Suture is a common term for the lin" of contact of the flat bones. It if a form of union admitting of no motion, and is somewhat varied according to to the degree of pressure they Lave to sustain They may be arranged thus: JlNCTURA IMMOBILIS. I. Svl ra Vera—Serrata.—Dentata. 2. Su'ur'i Spuria —Linea—Harmonia. « 3. SutuA Squamosa.- Limbosa. 4 Gomphosis Monro {Anatomy of the. Human Bones') expresses the common opinion, that " the suture u is formed by the two bones meeting while they are thus flexihle and yielding, and have " not yet come to their full extent of growth, so that they mutual I v force into the inter- " sticesof each other, till in»eting with such res-i-tance as tlmy are not able^ppovercome, " they are stopt fVom sprouting out further or are reflected. ,ie» we call also ceiuin great veins by the same nam • of singes ; thus the peat veins being enlarged where t.iey approach the heart, ;ind the veins beinii ;urticul;trlv lnrge in the brain and the womb, w e call them the sinuses of the heart, of the brain, aud of the womb. S8 DESCRIPTION of the by the same rule, the eyes should be also a part of the same organ, since they are pained, and tears begin to flow : but we do know that they belong to the voice, and raise its tone, for we feel the trembling note resound 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 suppressed 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 they enlarge gradually, and are fully formed about the fif- teenth year, the vox rauca, the breaking of the voice, which is observed 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 mis- take lies in supposing these cavities to raise the tone or note in which we speak, while they only add clearness and strength. The membrane which lines these cavities is thin, exquisitely sen- ibie, and is a continuation of the common membrane of the throat and nose. A thin humour is poured out upon its surface to moisten it and keep it right. This the ancients did not consider as a mere 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 conse- quence to promote. They are subject to one accident chiefly, viz. insects which nestle there, and produce inconceivable distress; and it is par- ticular, that they 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 seeking their food, they carry their nose upon the ground ; and it has been prov- ed, 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 pecu- liar to spoiling corn; while others have had the complaint, by sleeping upon the grass. But there is something very par- ticular in this, that far the greater number of these worms have * I have seen a boy of four years of age, whose parts of generation were prematurely developed with bushy hair upon the pubes. This man-child had the rough broken voice, though the bones of the forehead were flat. C. B. INDIVIDUAL BONES OF THE SKULL. 39 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 unfrequently covered with hair. There are reports which seem to prove, that some have died of this complaint, and in a very miserable 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 trepan- ning of these sinuses has often been proposed; but I have never read of a well marked case, so that we could be assur- ed beforehand of finding worms: they have, in most cases, been discovered rather by chance. The patient might be re- lieved on easier terms, by the injection of aloes, assafoetida, myrrh, the use of snuff or smoaking, and pressing the fumes upwards into the nose. Much should be tried, before under- taking a dangerous operation on such slender proofs. It may be right in cases of fractures, to decline applying the trepan above the sinuses, unless a fracture cannot be raised in any easier way; and we must be.especially careful to distin- guish a fracture of the outer table only, from entire fractures of this bone. For Palfin says, that the outer table being bro- ken, and the natural mucus of the sinus being corrupted and flowing out, has been mistaken for the substance of. the brain itself. And Paree, who first gives this caution, affirms, "jhat " 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 according to the age. The spine is more prominent at its root; but as it ad- vances 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 ; 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 the l"'e descended through both tables into the nose, believed iliat the dangerous and ungovernable bleedings at the nose mn,t be through this hole, and from the fore end, or beginning <,!' ihe longitudinal sinus. * For a more p-.rf....t accouut of the pathology of the sinuses, see the Surgery, 4to. vol. ii. 40 DESCRIPTION OF THE The orbitary process already described, is the most re- markable point of the frontal bone. The orbitary process-. es are two thin plates, departing 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 exqui- sitely smooth below, and on their upper surfaces, they are im- pressed with the frequent convolutions of the brain ; so that a wound through the eye endangers more than the eye ; for it passes easily forward into the brain, and is instantly fatal; it is the aim of the 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; the one is very small, and deeper at the inner corner of the eye, under the superciliary hole, which is the mark of the small cartilaginous pulley, in which the tendon of one of the muscles of the eye plays; the other, a more gentle and diffu- sed 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 secretes the tears, and keeps the eye moist.* PARIETAL BONE.—The parietal bones form much the greater share of the cranium : they are more exposed than any others, are the most frequently broken, and the most easily trepanned; for the parietal bones are more uniform in their thickness, and more regular in their two tables and diploe, than any others. But the accidental varieties of pits and depression 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. The square form of the bone produces four angles ; and in surgery, we speak of the frontal, the occipital, the mastoidean, and temporal angles, of the parietal bone.f It has deeply ser- rated edges, which unite the two bones with each other, and with the occipital and frontal bones. All the corners of this bone are obtuse, except that one which lies in the temple, and which, running out to a greater length than the other corners, is sometimes named the spinous or temporal process of the parietal boqe, though there can be no true process in a bone so * In addition, as points of demonstration, we may add the eminentia frontales, and v perciliara. t It enters into the coronal, the sagittal, the lambdoidal, and the smuimovs suture* INDIVIDUAL BONES OF THE SKULL. 41 regular and flat. The lower edge of the bone is a neat semi- circle, which joins the parietal to the temporal bone ; and the edge of each is so slaunted 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 semi-circular ridge, where the bone is particularly white and hard ; and rays extend downwards from this, con- verging towards the jugum. The white semi-circular line represents the origin of the temporal muscle; and th"e con- verging lines express the manner in which the fibres of the muscle are gathered into a smaller compass, to pass under the jugum, or arch of the temple. The sagittal suture, or meet- ing of the two parietals, is marked with a groove as big as the finger, which holds the longitudinal sinus, or great vein of the brain ; but the groove is not so distinctly seen, unless the two bones are put together ; for one half of this flat groove belongs to each bone. The great artery of the dura mater touches the bone at that angle of it which lies in the temple. It traverses the bone from corner to corner, spreading from the first point, like? the branches of a tree : it beats deep into the bone where it first touches it; but where it expands into branches, its impressions are very slight; commonly it makes a groove only, but some- times it is entirely buried in the bone; so that at the lower corner of the parietal, 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 the 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. On the inner surface of the bone, and near the sagittal edge, we very often see a pit or foveae, which receives one of those bodies which are called glards, of the dura mater. The lateral sinus makes a depression on the inside of the mastoidean angle. 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 foUiolum, from its resembling a . trefoil leaf, and was named by the ancients hypothetically, bregma, fans,* or fountain ; they thinking it a drain of moisture from the brain; and so the parietal bones are named ossa bregmatis. * The word pulsatilis, or fons pulsatilis, or beating fountain, was added, because we feel the liearing of the arteries of the brain there. VOL. I. F 42 DESCRIPTION OF THE OS OCCIPtTIS, has also the names of os memoriae, and os nervosum.* It is the thickest of the cranial bones, but it is the least regular in its thickness,, being transparent in some places, and in others swelling into ridges of very firm bone. It gives origin or insertion to many of the great muscles, which move the head and neck; it supports the back part of the brain, 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. This bone is united to the parietal bones by the lambdoid suture, to the mastoidean portions of the temporal bone by the additamentum suturse lambdoidalis, laterally and forward it is attached to the petrous portion of the temporal bone, and at its lower and most anterior part, it is attached to the sphe- noid bone, by that peculiar bond of union called synostosis. The external surface is exceedingly irregular, by the impressions of the great nicies of the neck : betwixt the insertions of the muscles, projecting lines are on the bone. In the middle of the bone, and betwixt the muscles of oppo- site sides, there runs a ridge from above downward; at the upper margin of the insertion of the trapezius, there is formed a superior transverse spine or ridge, and in the same way, di- rectly above the insertion of the recti, which make two irre- gular depressions, there is an inferior transverse spine. In a strong man, advanced in years, where the ridges and hollows are sirongly marked, the point where the superior transverse crosses the perpendicular one, it is so very promine t, 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 larger, more regular, smooth, and equal, and making only one transverse line, and one perpendicular line. The tentorium ce.re.bdlo super-exten- sura, is a diaphragm or transverse partition, which crosses the skull at its hack part; cuts off from the rest of the cranium the hollow of the occipital bone, appropriates that cavity for the cerebellum, and defends the cerebellum from the weight and pressure of the brain. • This tentorium, or transverse membrane, is attached to the great internal hi doe of the occipital bone. In the angle where this membrane is fixed to the ridge, lies the great sinus or vein, which is called longitu- diual sinus, while it is running along the head ; but the same * In beginning the demonstration, we point out its divisions : 1. Pars occipitalis. 2. Pars later > or condyloidea. '.i. Pars basilaris or cunifonnis; which at birth are di>tincl bones divided bv cartilage It is also necessary to name its angles, via. the superior or parietal tingle, and the mastoidean angle. INDIVIDUAL BONES OF THE SKULL. 43 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 forking of the longitudinal, into the lateral sinuses, mokes a triangular or tripod-like groove, which follows the internal ridges of the occipital bone : and above and be- low the transverse ridge there are formed four plain and smooth hollows. The two upper ones, are above the tento- rium, and contain the posterior lobes of the brain ; the two lower ones are under the tentorium, and hold the lobes of the cerebellum or little brain. Processes. The processes or projections of the occipital bone are few and simple. 1. There is a part of the bone which runs forward from the place of the foramen magnum, lies in the very centre of the base of the skull, joins the occi- pital 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 cuniform, or wedge-like process of the occi- pital hone. On the inside of this part of the bone is a slight hollow, to which the name of fossa basilaris is given, and lateral to this the groove of the lower petrous sinus may be observ- ed. And 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 flattened ; 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 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 joint to the corres- ponding bone of the neck. On the lower part of the cuniform process, there are two tubercles for the attachment of the recticapitis anteriores. Near the condyle, and immediately behind the foramen lacer- uni there is a tubercle for the rectus capitis lateralis. Holes.—These condyles stand just on the edge of the fora- men magnum, or great hole of the head, which transmits the spinal marrow, or continuation of the brain ; and the edges of tins hole (which is almost a regular circle) are turned aad 44 DESCRIPTION OF THE smoothed ; a little thicker at the lip, and having a roughness behind that giving a firm hold to a ligament, which, departing from this hole, goes down ihiough 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 the vertebral vein. There comes up through if* 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 accessory nerve. 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 ^ double ; it transmits the ninth pair, or great lingual nerve. There is another hole smaller, and less regular than this last. It is exactly behind the condyle, while the lingual h°le 's be- fore it. It is for permitting a small 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. 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. TEMPORAL BONE.—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 squamosa 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 bony, is hard, irregular, rocky ; just in- wards towards the basis of the skull; contains the organs 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 mastoidean 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. The squamous part is grooved, to make the squamous suture; is scolloped or fringed; and exceedingly thin on its edge ; it is radiated, in consequence of its original ossification shooting out its 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 - The interior and posterior semi-circular canals are protuberant upon its surfaces INDIVIDUAL BONES OF THE SKULL. 45 of the teeth. Where it projects into the base, it has several open points, which are filled up with cartilaginous or ligamen- tous substance ; and its occipital angle is connected with the other bones by the additamentum suturas squamosa?. The temporal bone closes the cranium, upon the lower and lateral part; backwards it is connected by the additamentum su- turalambdoidalis to the occipital bone ; by the squamous suture and the additamentum suturaj squamosa:, it isjoined to the parie- tal bone ; whilst anteriorly it is united to the sphenoid bone by the spheno-temporal suture, the spinous process of the sphe- noid bone being deeply wedged betwixt the petrous and squa- mous portions of the temporal bone. Processes. The zygomatic process rises broad and flat before the ear; grows gradually smaller as it stretches for- ward to reach the cheek-bone : it forms with it a zygoma, yoke, or arch of the temple, under which the temporal muscle plays. The temporal muscle is strengthened by a firm cover- ing 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 masseter, which moves the jaw; and one named zygomaticus, or distorter oris, because it draws the an- gle of the mouth. The zygomatic process is united by a short suture to the cheek bone. 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 jaws; so that it gives convenient origin to a ligament which goes downwards to support the os hyoides, or bone of the tongue ; and it is the origin of many curious mus- cles, chiefly of the throat and jaws. One slender muscle going downwards from the styloid process, and expanding over the pharynx, is called stylopharyngeus; one going to the os hyoides, is the stylohyoideus ; 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, rais- ing according to their insertions, one the pharynx, pnother the os hyoides, another the tongue. Processus vaginalis will not be easily found, nor ac- knowledged as a process; for it is only a small rising of*a ridge- of the bone, with a rouu,!i and brokeh-like edge, on the middle of which the styloid process stands : it is, in short, the 46 DESCRIPTION OF THE root of the stvloid process which anatomists have chosen to observe, though it gives origin to no particular part; and which they nave named vaginalis, as if it resembled a sheath for the styloid process. . Mastoid bus or mammillarts, 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 middle 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 muscle j and the point or nipple of this process is the point into which the mastoid muscle is inserted from before; and the co-mplexus obliquus and trachelomastoideus muscles from behind. It has been proposed of late years, that, in certain cases of deafness, we should open this part with the trepan. 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 extended 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 fair- ly united to the bone, and is named the processus-auditorius; and may be defined a circle, or ring of bone, with a rough ir- regular edge; the drum or membrane of the ear is extended upon it, and the cartilaginous tube of the ear is fixed,to it j and • this ring occupies the space from the root of the mamillary to the root of the zygomatic process. Betwixt this and the mastoid process there is a kind of fis-. sure, the rima mastoidea. The lower jaw is articulated with this bone by a shallow fossa, which is anterior to the auditory process, and at the root of the zygomatic process. A tubercle immediately be- fore this articulating surface deepens it. A fissure may be observed in nearly the middle of the cavity, which is for the attachment of the ligament, which unites the intermediate cartilage of this articulation. This fissure divides the proper articular or glenoid cavity from that fossa which giVts lodge- ment to a deep portion of the parotid gland. 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 to'let them out; others for the free passage of air to the iniernal ear. The meatus auditorius externus (the circle of which has been dercribed) is covered with the membrane of the '* In brutes it is indeed a process standing out. INDIVIDUAL BONES OF THIS SKULL. 47 drum, and communicates the vibratory motion of the air for moving and exciting the internal organs. 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 are seen many small holes, the meaning of which is this: the auditory nerve is double from its very origin in the brain : it consists, 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 cochlea, semi- 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 mollis, enter together; they fill the greater hole, and then they part: the portio dura, entering by one distinct hole, lakes its course along a distinct canal, the aque- duct of Fallopius from which it comes out upon the cheelij while the portio mollis, entering by many smaller holes inff> the cochlea, semi-circular canals, and other internal parts of the ear, is expanded in these cavities to form the proper organ of hearing. There is a small hole which will admit the point of a pin upon the fore part of the petrous bone. 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. The hole by which the portio dura passes out upon the cheek, is found just before the mastoid, and behind the sty- loid process; and being betwixt the two, it is named the sty- lomastoid hole, and is so small, as just to admit a pin. The hole for the Eustachian tube is very irregular. No air can pass through the membrane of the drum ; and as air is ne- cessary within the ear, it is conveyed upwards from the palate 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 48 DESCRIPTION* OF THE enough to receive the point of the finger, it grows gradually smaller as it advances towards the ear: it is cartilaginous 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 opens 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 ear, as in the place of the Eustachian tube; when we dive, we feel the same, by the condensation of the air; and sometimes by forcing the air strongly upwards through the ear, or by vo- mits, obstruction of the Eustachian tube, and the deafness which attends that, accident, are very suddenly, and, we may say, violently removed; or sometimes the cure is attempted by syringing, or by cleaning the mouth of this tube with a probe, just as we do the external ear. Above and to the outside of the Eustachian tube there is a narrow canal which conveys the nerve called corda tympani. This nerve, traversing the tympanum, enters into the aqueduct ofFalopius, and unites with the facial nerve. "^POn the inside of the Eustachian tube we may observe a ca- nal which, leading backwards, opens into the cavity of the tym- panum with a mouth like a spoon, it gives lodgement to the long muscle of the maleus. The other holes do not relate to the ear, and are chiefly for transmitting the great blood vessels of the brain. The carotid artery, the chief artery of the brain, enters mto 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 little crooked, and very smooth within. There seems to be a par- ticular 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 prtery being prevented from entering the brain in one great trunk, by a curious division into many branches, INDIVIDUAL BONES OF THE SKULL. 49 which meet again. It is at this particular point that we are sensible in our own body of the beating of these two great ar- teries ; and Haller is at pains to inform us, that, during a fever, he felt this beating in a very distressing degree. The great lateral sinus comes out m part through the temporal bone, to form the internal jugular vein. The course of the sinus may be easily traced by the groove of the occi- pital 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 receive 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 half by the occipital bone. This hole is very large; is lacerated or ragged-like. It is sometimes di- vided into two openings, by a small point, or spige 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 the stomach, *long 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, the superior petrous sinus going towards the end of the lateral si- nus. *J*V There is a small hole on the outside of this bone, in i^L occipital angle ; or rather the hole is oftener found in the line of the suture (the additamentum suturae squamosae). 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. There are two very small canals, which probably carry lym- phatics from the inner cavities of the ear; they have been called aqueductus vestibuli, and aqueductus cochleae; they open on the petrous bone, near the internal auditory foramen. Among the irregular depressions on the different faces of this bone are sometimes enumerated these: the groove al- ready mentioned on the mastoid process for the lodgement of the head of the digastricus ; certain cerebral fossa?, which are the impressions of the convolutions of the brain upon the in- side of the squamous portion ; the jugular fossa, or thimble- *like depression, made by the first turn of the great jugular vein ; the temporal sinuosity for the lodgement of the tempo- ral muscle; and, lastly, we observe in a well marked bone. the sulci for the artery of the dura mater. G 50 DESCRIPTION OF THE The ^ETHMOID BONE—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 consist- ing of many convoluted plates, which form a net-work like honey-comb. It is curiously enclosed 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, re- ceive the divided nerves, and give them an opportunity of expanding into the organ of smelling; and these bones, upon which the olfactory nerves are spread out, are so much con- voluted, as to extend the surface of this sense very greatly, and are fiamed spongy bones. Another flat plate lies in the orbit of the eye, which being very smooth, by the rolling of the eye, 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. Thus the aethmoid is united to the frontal bone, by the linea aethmoidea frontalis, and to the sphenoid bone by a similar line of contact, visible on the inside of the basa„if the cranium. Looking into the orbit, we ("{"gain see a union with the frontal, and with the sphenoidal i and palate bones. Its perpendicular plate stands connected to the back part of the nasal process of the frontal bone ; the vomer is attached to the back part of this plate. The ossa unguis close the cells of this bone anteriorly. 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 orbitary 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 r6ots 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 perpendicular, one above, and three below. The first perpendicular process is what is called crista* galli, a small perpendicular projection somewhat like a cock's" comb, but exceedingly small, standing directly upwards from the middle of the cribriform plate, and dividing that plate into two ; so that one olfactory nerve lies upon each side of the crista galli; and the root of the falx, or septum, betwixt, the two hemispheres of the brain, begins from this process. INDIVIDUAL BONES OF THE SKULL. 51 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. Exactly oposite 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 comonly inclined a little to one or other side, so as to make the nostrils of unequal size. The azygous process is uni- ted with the vomer, which forms the chief part of the parti- tion ; 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 aethmoid bone or the vomer. The lateral parts of the aethmoid bone consists of a series of cells communicating with each other, and which are called the labyrinths. The cells of the labyrinth are closed by the external plate called os planum. These cells belong to the organ of smelling, and are useful by detaining the effluvia of odorous bodies, and by reverberating the voice. From each of these labyrinths there hangs down a spongy bone, one hanging in each nostril. They are each rolled jh like a scroll of parchment; they are very spongy; are covered with a delicate and sensible membrane, and when the olfac- tory 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 impres- sion be perfect. Their convolutions are more numerous in the lower animals, in proportion as they need a more acute sense. They are named spongy, or turbinated bones, from their con- volutions, resembling the many folds of a turban. The orbitary plate of the arthmoid bone is a large sur- face, 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. When we see it in the detached bone, we know it to be jusi the flat side of the aithmoid bone ; but while it is inoased 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. 52 DESCRIPTION OF THE 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 fingernail (whence it has its name,) yet in the adult the os unguis is firmly attached to the a:thmoid 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, it exposes the cells. 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. The cells of the aethmoid bone, which form so important a share of the organ of smell, are arranged in great numbers, along the spongy bone. They are small1 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 belong 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 un- dermines all the face; how the venereal disease, having af- fected 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 par- tition, might depress the delicate cribriform plate, so as to oppress the brain with all the effects of a fractured skull, and without any operation which could give relief. And we also see much danger in pulling away polypi, which are firmly at- tached to the upper spongy bone. SPHENOIDAL BONE.—The sphenoidal bone completes the cranium, and closes it below. It is named sphenoid cu- niform, or wedge-like bone, from its being incased in the very basis of the skull; or it is named os multiforme, from its irregular shape. It is united to fourteen distinct bones. It is much of the shape of a bat, whence it is often named the * The number is commonly twelve, but not regularly so. INDIVIDUAL BONES OF THE SKULL. 53 pterygoid rone, its temporal processes being like extended wings ; its proper pterygoid processes 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 oi 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 cen- tre of the skull, and transmits five of the nerves from the brain, besides a reflected nerve ; but still the body bears so small a proportion to the bone, that we have not a regular centre to which all the processes can be referred; so that we are al- ways, in describing this bone, moving forwards from point to point, from one process or hole to the next. PROCESSES.—The xlm, or wings, often named tempo- ral processes, rise up in the temple, to form part of the hollow of the temple ; and the 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. The other side of this same process looks towards the socket of the eye, and has a very regular and smooth surface; it is opposite to the os planum. As the a;thmoid 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 sphe- noid bone, or orbitary plate of the great ala. The surface of the great wing -which looks backwards, re- ceives the middle lobe of the cerebrum and is called the cerebral FosbA ; and that which is external and receiving the temporal muscle, is called the temporal fossa. The lower, or back part of this bone runs out into a nar- row point, which sinks in under the petrous portion of the temporal bone, and being sharp pointed, it is named the spi- nous process. It is very remarkable for a small hole which permits the great artery of the dura mater to enter. 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 condyle of the lower jaw, and being a small point, like the point of the stylus, or iron-pen, it also is named styloid process. The lesser wing of Ingrasias next attracts the eye. It is tha; part of the bone which unites (by harmonia) with the orbituy plate of the frontal bone, and with the athmoid bone. This lesser wing projects laterally into the transverse spi- nous process. I 45 description of the 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. Each external pterygoid process is thin and broad, and extends farther backwards. Each internal pterygoid pro- cess is taller and more slender, and not so broad. It has its end rising higher than the other, and tipped with a small neat hook, named the hook of the pterygoid process, (viz. the hamular process.) The inner pterygoid processes, form the back of the nostrils. The hook of the pterygoid process, is called the hook of the palate, of which it forms the backmost point. The musculus 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 sideways, or for its grinding motions, arise from the pterygoid processes. Be- twixt the two processes there is a hollow which is called the fossa pterygoidea. The azygous process,-)- 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. The vomer, or proper bone of the par- tition, stands with a split edge, astrida over this process, so as to have a very firm seat. A kind of union which has been called gomphosis. The clynoid processes have, like many parts of the human body, a very whimsical name, very ill suited to express their form; for it is not easy, in this instance, to acknowledge the likeness of four little knobs to bed-posts; yet the clynoid pro- cesses are very remarkable. The two anterior clynoid processes are small bumps, rather sharp, projecting back- wards, and terminating in two flat projecting points. The posterior clynoid processes rise about an inch farther backwards, and are, as it were, opposed to the others. They rise in one broad and flat process, which divides above into * There ii some confusion in this name, since pterygoid signifies aliform, or wing-like processes. i Azygous is a term, which is applied to such parts as have no fellow; because almost al- ways the parts on one side of the body are balanced by similar and corresponding part* 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 botes; or the azygous vein, which runs in the centre of the thorax, and is single. \ I INDIVIDUAL BONES OF THE SKULL. 55 two points, small and round, or nobby at their points; and they look forwards towards the anterior clynoid processes. The tuberculum olivary is an eminence betwixt the an- terior clynoid process and before the sella turcica. The sella turcica ephipfum, or Turkish saddle, is the space enclosed by these four process^, and is well named. The sella turcica, supports the pituitary gland, an appendage of the brain, the use of which is unknown. The carotid ar- teries 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 distinguish- ed ; since, in many skulls, they form but one broad process. On the side of the posterior clynoid process, the carotid ar- tery as it rises impresses its form upon the bone. The cone or triangular process is singularly placed in obscu* rity, when the bones are in union, and in separating the sphe- noid bone it is very apt to be broken off. This process closes the cell, and projects laterally towards the deepest part of the orbit, but so as to be concealed by the palate bone. 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 middle 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