•r

THE LIBRARY

OF
THE UNIVERSITY

OF CALIFORNIA

PRESENTED BY

PROF. CHARLES A. KOFOID AND
MRS. PRUDENCE W. KOFOID

SYSTEM OF ANATOMY

FOR THE USE OF

STUDENTS OF MEDICINE.

BY CASPAR WISTAR, M.D.,

LATE PROFESSOR OF ANATOMY IN THE UNIVERSITY OF PENNSYLVANIA.

WITH NOTES AND ADDITIONS,
BY WILLIAM E. HORNER, M. D.,

PROFESSOR OF ANATOMY IN THE UNIVERSITY OF PENNSYLVANIA.

NINTH EDITION,
ENTIRELY REMODELED,

AND ILLUSTRATED BY MORE THAN TWO HUNDRED ENGRAVINGS.

BY J. PANCOAST, M. D.,

PROFESSOR OF GENERAL DESCRIPTIVE AND SURGICAL ANATOMY IN JEFFERSON MEDICAL

COLLEGE OF PHILADELPHIA, LECTURER ON CLINICAL SURGERY, FELLOW

OF THE PHILADELPHIA COLLEGE OF PHYSICIANS, ETC., ETC.

IN TWO VOLUMES.
VOL. I.

PHILADELPHIA:

THOMAS, COWPERTHWAIT & CO.
1846.

ENTERED, according to the Act of Congress, in the year 1842, by

THOMAS, COWPERTHWAIT & CO.,
In the Clerk's Office of the District Court of the Eastern District of Pennsylvania.

GREENFIELD, MASS.
MERRIAM AND MIRICK, PRINTERS.

ADVERTISEMENT TO THE NINTH EDITION OF WISTAR'S ANATOMY.

THE increasing estimation in which this favorite Work on Anatomy is held
by the Medical Profession of this country, having already caused the last
unusually large edition to be exhausted, the publishers in passing the ninth
edition through the press, have been desirous of rendering it wWthy of the
continuance of such gratifying support, by having such additions and improve-
ments made as the progress of the science required. With this object the text
introduced by the editor, has been subject to revision ; much new matter has
also been added, with a care however, not so to extend the work as to impair its
character for clearness, brevity, and simplicity, which has made it so great a
favorite with the Medical Student. Several wood cuts have been added, and
the copperplate illustrations of the Arteries by Sir C. Bell, which were formerly
sold separate, at a cost greater than the whole of this work, have been renewed
by a skillful engraver, so as to serve not only as an ornament to the book, but
an aid of the greatest importance to the Student.

JOSEPH PANCOAST.
Philadelphia, 1846.

ADVERTISEMENT TO THE EIGHTH EDITION.

THE publishers of " Wistar's Anatomy for the use of Students of Medicine,"
gratified with the favorable reception, which their attempt to enlarge and illus-
trate this well known work has met with, have resolved in preparing another
edition for the press, to render it as far as is in their power, deserving of a continu-
ation of the patronage it has received. For this purpose it has been carefully re-
vised and enlarged so as to include such important additions and investigations of
interest as have been recently made in the science. By comparing the present
with the former editions, the reader will discover that these have been both
numerous and important in each division of the subject. This the publishers
have been enabled to do without much increasing the size of the volumes, by
substituting, for the old copperplate prints, a very large number of engravings
on wood, of the finest description. These which are intercalated with the text
and explained by foot notes, cannot fail to render the work more convenient and
valuable as a text-book, in the various schools in which it has been adopted,
and at the same time make it serve as a most useful guide to the student in the
study of practical anatomy. The additional illustrations have been taken
mainly from Wilson's Anatomist's Vade Mecum, (London, 1842,) and partly
from the English edition of Cruvielhier's Anatomy, (London, 1842,) and from
the recent splendid work on General Anatomy, by F. Gerber. The present
edition of Wistar, contains eight colored copperplate engravings of the blood-
vessels, and upwards of two hundred and twenty engravings on wood, rendering
it in this respect more richly and amply illustrated than any other book of the
kind that has yet been offered to the American student.

The same plan has been pursued as mentioned in the preface to the seventh
edition, of distinguishing the new matter that has been added, from the original
text of Dr. Wistar.

JOSEPH PANCOAST.
Philadelphia, 1842.

DR. HOMER'S PREFACE.

THE value of the present work having been sufficiently tested by its very
diffused use in the profession, and by a third edition being now called for, the
editor has been induced to superintend the latter, with a hope that its utility and
the public conviction in its favor have been in no wise diminished. The close-
ness of the connexion between himself and its lamented author, furnished, also,
another and a very powerful reason, why he should endeavor by such means
as he commanded, to contribute to perpetuate the memory of a man whose
literary and professional career had been so conducive to the reputation of his
country, and whose philanthropy and suavity of manners had established him
so firmly in the affections and confidence of all who knew him.

Several amendments have been introduced by the way of corrections, altera-
tions and additions. The latter, for the most part, appear between brackets,
and in the form of notes, but there are many which could not be marked in
such a manner without giving the text a garbled appearance, they therefore
appear as portions of the original work.

The whole mass of matter introduced as amendments is greater, indeed, than
a superficial perusal of the work would intimate ; and the only way for the
reader to arrive at it, will be by a careful comparison of the last with the pre-
sent edition. The editor, however, has been careful not to allow the spirit of
change or improvement to affect the work in any points except such as seemed
to him absolutely to require it, and where he was fully warranted by the best
authorities in Descriptive Anatomy. It would have been sufficiently easy for
him to have extended the work considerably beyond its present dimensions ;
but from its having been originally designed as a text-book of the course of
Lectures on Anatomy in the University of Pennsylvania, and for the benefit of
practitioners, who are always most assisted by condensed views on this subject,
he was apprehensive of perverting or of frustrating its objects by such exten-
sion. In consequence of which he has principally confined himself to adding
where additions were called for by recent discoveries in Anatomy, and by the
omission of older ones.

Philadelphia, Oct. 10th, 1823.

PREFACE TO THE SEVENTH EDITION/

THE publication of the first edition of his " System of Anatomy for the use
of Medical Students/' was completed by Dr. Caspar Wistar in 1814. Simple
in its construction, concise, but yet clear, and at the same time representing
faithfully and fully, the science of Anatomy as it then existed, the book was
exactly in keeping with the well known character of its distinguished author.
The general approval with which it was received in this country, was manifest-
ed by the rapidity of its sale.

The second edition which was called for in 1817, was further improved by
the author, by the addition of such new anatomical facts as had come to his
knowledge, and such further physiological observations as served to give life
and interest, to the otherwise dry details of his science. In 1818. before his
work had reached the third edition, the author himself died, regretted by all
who loved virtue, honored science, or knew how to estimate a kindness of soul,
and uniform urbanity of manner, which is yet vivid in the recollection of his
friends.

The superintendence of the third edition was assumed by Professor Homer,
a personal friend of Dr. Wistar, who enriched it, by the addition of much valu*
able matter, which the science in its onward progress had at that time develop-
ed. The value of these additions, may be inferred, from the increasing favor
which the medical public has continued to extend towards the work; four
editions having been completely exhausted since that period.

Though fifteen years only have elapsed, since its former revision, the zealous
and persevering inquiries of modern anatomists, which have scarcely their par-
allel in any other department, have in that time added much to the science.
The present publishers have therefore been desirous, that the work should be so
extended and remodeled, as to be brought up as near as may be, to the existing
state of the science, without impairing its value as a manual by too much in-
creasing its bulk. The reader will discover how far the attempt has been suc-
cessful, by comparing this with former editions.

Within the period alluded to, the department of general, more than that of
special anatomy, has yielded the richest harvest to the anatomist, and has been
advantageously cultivated with particular reference to physiology and thera-
peutics. From general, then, more than from special anatomy, have the pre-
sent additions been derived; the editor believing that in mere special descrip-
tion, that which is most concise and yet so comprehensive as not to omit any
I*

VI PREFACE.

thing of real importance, is the best. He has not, therefore, added a great deal
to the individual description of the bones, ligaments, muscles, blood-vessels,
and nerves. But in the department of General Anatomy, and especially in
Splanchnology — the viscera being so important in a medical point of view —
the student will find the additions to have been both numerous and extensive.

The department of Neurology, which has been the fashionable anatomical
study, for years past, and upon which hangs so much that is important in
physiology and medicine, has appeared to him more deficient than any other
portion of the original work, as the brain and spinal marrow have been describ-
ed by Dr. Wistar, only from above downwards ; a method which was, however,
the most approved and general in his day. The editor has therefore added two
entire chapters on that subject, one on the General Anatomy of the Nervous
vSystem, and one on the special description of the Spinal Marrow and Brain
from below upwards, in the order of its development and the direction of its
functions, retaining, nevertheless, here as in other parts, all the original text.
It has also been thought advisable, to transpose several portions of the work,
when by so doing, parts belonging to the same general tissue could be placed
in more natural connexion, and made to correspond with the mode in which
they are usually described.

Thus, the account of the brain, the eye and the ear, has been transferred from
the first volume to the second, and placed in continuity with that of the other parts
of the general nervous system. To facilitate the student in the aquisition of
this difficult science, all the plates of the former edition, which were sufficiently
accurate to be useful, have been retained, and several other copperplate engrav-
ings of the blood-vessels added, with upwards of a hundred wood cuts, some
of which are original, but the greater part collected with considerable care and
labor from the newest and most approved sources.

The amount of the new matter added to this edition is nearly equal to a
fourth part of the whole. The student, will, however, be enabled to distinguish
readily the original text of Dr. Wistar, from the additions which have been
made either by Dr. Horner, which are all included in brackets [], or from those
of the present editor, which are separated from the other parts of the work by
their commencing and terminating with a dash — . Various synonyms introduc-
ed throughout the work, and some more trifling emendations of the text, it has
not been thought necessary to designate.

JOSEPH PANCOAST.

Philadelphia, Dec. 1, 1838.

CONTENTS OF VOL. I.

PART I.

OSTEOLOGY.
CHAPTER I.

GENERAL ANATOMY OF THE OSSEOUS SYSTEM.

CLASSIFICATION and Structure of Bones, - - - - 13

Of the Periosteum, - - - 33

Medullary Membrane or Internal Periosteum, - 33

Cartilages and their Structure, - 36

Accidental development of Cartilages, - - 39

Of the Formation of Bone, 40

Formation of Callus, - -48

Terms used in the Description of Bones and Joints, 51

CHAPTER II.

OF THE SKELETON AND ITS DIFFERENT PARTS.

Of the Head, - - . - 54

Sutures, - 57

Os Frontis, - 61

Ossa Parietalia, - - 64

Ossa Temporum, 66

Qs Occipitis, ... 73

Os Ethmoides, - - - 75

Os Sphenoides, - - - - 80
Foramina of the Sphenoidal Bone, - ... 84

Of the Face, - ... 85

Ossa Maxillaria Superiora, - - - 86

Ossa Nasi, ... 89

Ossa Lacrymalia seu Unguis, - - - 90

Ossa Malarum, - - - - 91
Ossa Palati, - .... 93

Ossa Spongiosa, or Turbinata Inferiora, - - - 95

Vill CONTENTS.

OftheVomer, - 95

Maxilla Inferior, - 96

Teeth, - 99

Composition of the Teeth, 100

Development of the Teeth, - - 1 10

Of the Enamel, - 112

Permanent Teeth, - - 113

Aberrations of Dentition, - 117

OsHyoides, *• - 118

Regions of the Skull, ' - 119

Orbit of the Eye, - - 120

Cavities of the Nose, - 122
Cavity of the Cranium and Internal Basis of the Skull, - 125

External Basis of the Skull, - 128

Side of the Head, - - 131

Form of the Cranium, - 132

Head of the Foetus, - - 135

Trunk, - 137

Spine, ... 137

True Vertebra, - 138

False Vertebra?, - 151

Vertebral Cavity for containing the Spinal Marrow, 154

Thorax, ( - 155

Ribs, 155

Sternum, - - 160

Movement of the Ribs and Sternum in Respiration, 163

Pelvis, - 163

Os Ilium, - 164

Os Ischium, - - 166

Os Pubis, - 167

Trunk of the Foetus, - - 173

Superior Extremities, - 174

Clavicle, - 175

Scapula, - 177

OsHumeri, - - 181

Forearm, - 185

Ulna, - - 186

Radius, - 188

Hand, - 190

Carpus, - 191

Metacarpus, - - - - - - -196

Thumb and Fingers, 199

Inferior Extremities, - - 201

CONTENTS. ]X

Of the Thigh, - - 201

Tibia, - - - 205

Fibula, --•„-- - 207

Patella, - 209

Foot, - . - 211

Tarsus, - - - 211

Metatarsus, 217

Toes, - 219

General Structure of the Foot, - 219

PART II.
SYNDESMOLOGY.

CHAPTER III.

GENERAL ANATOMY OF THE LIGAMENTOUS, FIBROUS, OR DESMOID TISSUE. 223

Ligaments of the Joints, - - 226

Of the Yellow Elastic Ligamentous Tissue, - 229

Fibro Cartilaginous Tissue, - - 230

CHAPTER IV.

A GENERAL ACCOUNT OF ARTICULATIONS, AND OF BURS.E MUCOS^. 232

CHAPTER V.

OF PARTICULAR ARTICULATIONS.

The Connexion of the Head with the Vertebrae, - - 239

Articulations of the Vertebrae with each other, -- 241

Articulation of the Lower Jaw, - - 244

Articulations of the Clavicle and Scapula, 245

Articulation of the Os Humeri and Scapula, - 246

. Elbow, 248

Wrist, - - 250

Carpal and Metacarpal Bones, - 254

Fingers, - - 255

Ribs, - 255

The Hip Joint, - 257

Articulation of the Knee, - 259

Tibia and Fibula, - 263

Leg, Foot, and Ankle Joint, 264

Tarsus and Metatarsus, - - - - 266

CONTENTS.

CHAPTER VI.

OF PARTICULAR LIGAMENTS AND THE SITUATION OF THE INDIVIDUAL

BURS-E MUCOS.&.

Ligaments proper to the Scapula, - - 268

Interosseous Ligament of the Forearm, - - 268

Ligaments retaining the Tendons of the Head and Fingers in their

position, - 269

Ligaments on the Anterior part of ike Thorax, - 270

of the Pelvis, - - 270

retaining the Tendons of the Foot, - 274

Enumeration of the most important Bursas, - 275

PART III.

MYOLOGY.

CHAPTER VII.

GENERAL ANATOMY OF THE MUSCLES. 279

Of the Tendons, and of Muscular Motion, - - 287
CHAPTER VIII.

OF THE INDIVIDUAL MUSCLES. 300

Muscles of the Teguments of the Cranium, - 300

Ear, 301

Eyelids, - 302

Eyeball, 303

Nose, - - 306

Mouth and Lips, - 306

Lower Jaw, - - 311

Anterior part of the Neck, 313

between the Lower Jaw and the Os Hyoides, - 314

Os Hyoides and the Trunk, 316

situated about the Fauces, - - 319

on the Anterior part of the Neck close to the Vertebrae, 321

on the Anterior part of the Thorax, - 323

between the Ribs, . _ . 334

on the Abdomen, - - - - _ 335

about the Male Organs of Generation, - 335

of the Anus, ----.„. 339

CONTENTS. XI

Muscles of the Female Organs of Generation, - 341

within the Cavity of the Abdomen, - 342

on the Posterior part of the Trunk, - 348

of the Superior Extremities, - 359

Inferior Extremities, - - -^/ 375

CHAPTER IX.

OBSERVATIONS ON THE MOTIONS OF THE SKELETON. 397

PART IV.

OF THE GENERAL INTEGUMENTS, OR OF THE

CELLULAR MEMBRANE AND THE SKIN. -

CHAPTER X.

OP THE CELLULAR MEMBRANE. 403

CHAPTER XL

Of the Cutis Vera, 411

Rete Mucosum, - 415

Derma, - 425

Papillary Body, or Neurothelic Apparatus, - - 425

Sudoriferous Apparatus, - - 426
Inhaling Apparatus, ------ 427

Blennogenous Apparatus, ... 428

Chromatogenous Apparatus, - - 429

Cuticle, or Epidermis, - 430

Nails, - 439

Hairs, ------- 441

PART V.

OF THE NOSE, THE MOUTH, AND THE THROAT.
CHAPTER XII.

OF THE EXTERNAL NOSE. 446

Of the Cavities of the Nose, - 449

CHAPTER XIII.

I

OF THE MOUTH. 458

Of the Tongue, - - - - - - - 462

The Salivary Glands, - - - - - - 469

Xll

• CONTENTS.

CHAPTER XIV.

OF THE THROAT. THE ISTHMUS AND FAUCES.

Of the Larynx,

Muscles of the Larynx, -
Thyroid Gland,
Pharynx, -

474

476

483
487
490

FAifr vi.

OF THE THORAX.

THE MAMMAE. 493

CHAPTER XV.

OF THE GENERAL CAVITY OF THE THORAX. 497

CHAPTER XVI.

OF THE HEART AND PERICARDIUM, AND THE GREAT VESSELS.

Of the Pericardium, - - 502

Heart, - 504
Aorta, Pulmonary Artery and Veins, and the Venae Cavse at

their commencement, - - 514

CHAPTER XVII.

OF THE TRACHEA AND THE LUNGS.

Of the Trachea, - 517

Lungs, - - - 520

Thorax of the Foetus, - 526

Thymus Gland, - 526

Heart, - 529

Pulmonary Artery end the Aorta, 531

Lungs of theTcetus, - 532

Cases of Malformation, - 533

,

-

SYSTEM OF ANATOM>Y.

PART I.

OSTEOLOGY.

CHAPTER I.

GENERAL ANATOMY OF THE OSSEOUS SYSTEM.

Classification and structure of bones— Chemical composition — Recent researches
on the intimate structure of bone — Periosteum — Medullary membrane — Car-
tilages— Formation of bone — Terms used in describing bones.

— THE osseous tissue in man and nearly all large animals
not inhabiting a dense medium, constitutes that scaffolding
or framework, upon which is supported all the soft parts of
the body. Hence the bones when seen in connexion in a
perfect skeleton, present so perfect an outline of the animal to
which they belonged, as to be sufficient as has been shown by
Baron Cuvier, to indicate clearly its shape, size, and mode of
life as well as the nature of the food upon which it lived.*
— The bones may be considered* as designed for the fulfilment
of two principal objects — the formation of cavities for the
protection of delicate and important organs, as in the head,
thorax, and pelvis — and of columns and levers for support and

* A skeleton, or a structure. analogous to it in its uses, that of forjpng a
foundation upon which the body can be built, and to which the muscles may be
attached in order to move it from place to place, is found in the mammiferae,
birds, and many fishes, in the interior of the body ; in the Crustacea and teslacea,
some fish, reptiles, &c., it is wholly or in part at the exterior. In a great
majority of cases it is bony in its structure ; it is, however, cartilaginous in
many fishes, and fibrous in nearly all coleopterous insects, of which it forms
the external covering.— p.

14 CLASSIFICATION OF THE BONES.

motion, as in the spinal column and the upper and lower ex-
tremities. They perform, however, but a passive or mechanical
part in the movements of the body, forming supporting organs,
round which the muscles, nerves and vessels are wreathed, and
at the same time serve as levers, by which the limbs are lifted.
They are necessarily very numerous in the human body, and
exist as separate and distinct pieces, which touch one another
at their extremities, where they are generally expanded in. size,
and their parts so nicely adjusted to each other, as to form
the basis of the structure of the joints. At these places of
junction, the bones are fastened together, by strong, fibrous,
inelastic, inextensible bands, called ligaments.
— The number of the bones in the human body, varies accord-
ingly as we examine them, in infancy, middle life, or in old
age. Nearly all the individual bones of the adult, are developed
in separate pieces in the infant, the number of which is very
great, and their consolidation into single bones, is not general
and complete till about the period of puberty : many of these
separate bones of the adult, especially of the head and trunk,
are found fused together in extreme old age.
— Anatomists have generally agreed to consider as distinct
bones, those of the adult, and to these they have given indi-
vidual names. The skeleton is divided into trunk, head, and
extremities :

—Thus there are for the trunk, fifty-three bones ; the twenty- ,
four true vertebras, the sacrum, the coccyx, twelve ribs on each
side, one sternum in three pieces, and two ossa innominata.
— For the head, fifty-nine bones ; the occipital, sphenoid,
ethmoid, frontal, the two parietal, two temporal with the four
small bones of the ear, the vomer, the two superior maxillary,
two palatine, two molar, two nasal, two lachrymal or unguiform,
iwo inferior turbinated, the inferior maxillary, the teeth, and the
hyoid bone.

— For the two upper extremities, seventy-four bones ; there are
on each side, the scapula, clavicle, humerus, radius, ulna, eight
wrist or carpal bones, five metacarpal, fourteen phalanges, and

five sesamoid bones.

- ?

CLASSIFICATION OF THE BONES. 15

— For the two lower extremities, sixty-six bones ; on each side
one femur, a tibia, a fibula, patella, seven ankle or tarsal bones,
five metatarsal, fourteen phalanges of the toes, and two and some-
times three sesamoid. Thus according to the enumeration of
Marjolin, there are two hundred and fifty-two bones in the human
body. The number of sesamoid bones, however, is very varia-
ble ; and some anatomists of high reputation, do not include the
teeth in the enumeration of the bones of the body.
— The bones are all either symmetrical or unsymmetrical.
The symmetrical bones are in pairs, and correspond in size
and shape very nearly with each other, and are placed upon
either side, like those of the extremities and ribs. The unsym-
metrical, which consist of some of the bones of the head, the
sternum, vertebrae, sacrum, os coccygis and os hyoides, are
situated in the middle line of the body. The lateral halves of
these bones correspond very closely with each other.
— From their general form and geometrical dimensions, the
bones have been divided into classes ; the long bones, ossa
longa, the broad bones, ossa lati, and the thick bones, OSSQ,
crassa. The long bones, occupy the centre of the limbs, are
the levers used in locomotion, and form a series of "broken
columns, articulated together, which increase in number, and
diminish in si^e, as they recede from the trunk. They are
divided into a middle part, body or diaphysis ; and into extre-
mities or epjphyses. The body is cylindrical in some, prismatic
and triangular in others, and generally a little curved or twisted.
The extremities are expanded and thick. The bodies which
are the smallest part, happily correspond with the bellies or
largest .part of the muscles — the extremities with their narrow
tendinous terminations.

— The broad bones assist in forming a part of the walls of the
trunk and head ; they are flattened, more or less concave on
their interior, varied in their form, and thicker usually at their
margins, than at their centres.

— The thick bones are assembled in masses, and form parts at
once solid and moveable as in the spinal column, the wrist, and
the ankle.

16 STRUCTURE OF THE BONES.

-«-

— The human bones in a recent adult subject, are of a dull
white color : they possess considerable elasticity, but little
flexibility, have the greatest specific gravity of any portion of
the human body, and (are liable to be broken by accidents or
even by violent muscular efforts. Their texture is varied not
only in different parts of the skeleton, but in different parts^of
the same bones. Thus in the long bones, the middle portion
or diaphysis is compact, or nearly solid, with a cavity in the
centre ; the extremities are cellular or spongy, with but a thin
coating of the compact matter; and the central cavity, is occu-
pied by a long network formed of thin plates and fibres, called
the reticulated tissue of the bones.

— In flat bones the external surfaces are composed of firm
plates of compact bone ; but the internal substance is cellular.
In some of these bones, the cellular tissue exists in such small
quantity, that the external compact layers almost touch, and the
bones become then diaphanous or translucent.
— The thick bones are formed almost entirely of the spongy or
cellular substance, which is surrounded by an extremely thin
shell of the compact bony matter, and are somewRat darker in
color than the long or the flat.

—The osseous tissue thus presents three modifications of form :
the compact, the reticular, and tho cellular ui spungy. The
compact, which is the densest and strongest, is placed upon the
outer surface of all the bones of the body ; it forms a covering
of greater or less thickness to all the flat and thick bones, and
adds to their strength, without much increasing their weight.
The long bones, which are narrowed down in the shaft, so as
to accommodate the muscles without destroying the symmetry
of the limbs, and require to be made of the strongest material,
have their shafts or bodies formed almost entirely of the com-
pact portion. The cellular or spongy is found, in a greater or
less degree, in every bone of the body ; in the extremities of
the long bones it is continuous, though indirectly, with the
reticulated tissue of the central or medullary canal. The
reticulated tissue has been considered only a modification of the
spongy, being formed of larger cells with a more open and
delicate texture.

STRUCTURE Q$ THE BONES, 17

[The cellular structure of bones is attended with several
important advantages. In the cylindrical bones it gives great
additional strength, by increasing their diameter, without adding
to their weight ; for by swelling out their articular e/tfemities,
it produces much greater security of the joints, by obviating the
tendency to dislocation, and rendering their movements more
steady. A simple experiment will satisfy any one that the
increase of volume in the extremities of the long bones, is not
attended with an increase of osseous matter; for in the dried
bone, the section of an inch from the centre gill weigh as much
as the same length from the extremities, notwithstanding the
greater size of the latter. *Dr. Physick has pointed out another
very important advantage of the cellular structure of bones,
besides those of its making them nearly as strong as if they
were solid, and at the same time diminishing what otherwise
would have been a weight too oppressive for the muscular
powers. He thinks that thereby the concussion of the brain,
and of the other viscera is frequently prevented ; and in nearly
all cases diminished, in falls and in blows. He illustrates the
position by showing, first, the concussion which takes place
through a series of ivory balls suspended by threads ; if one be
drawn to some distance from the others, and allowed to impel
them by falling. The momentum in this case impels the ball at
the farther end of the row, almost to the distance from which
the first one fell. But if a ball of the same size, composed of
the cellular structure of bone, be substituted for one of the ivory
balls, and the experiment be repeated, the momentum of the
first ball is lost almost entirely in the cellular structure of the
substitute ; particularly if the latter be well soaked previously in
water, so as to give it a condition in point of moisture allied to
the living state. Adopting this experiment as demonstrative of
the fact, Dr. Physick asserts, that in falls from an eminence
upon the feet, the percussion, by the time it has passed through
the cellular structure of the foot, leg, thigh, vertebral column
and the condyles of the occiput, is very much diminished in
force, and carries much less impulse upon the brain. / Again, in
2*

18 STRUCTURE OF THE BONES.

blows on the head, the brain, though much protected from
external injury by the arched form of the cranium, has an
additional security -from the interposition of the diploe, wKich
weakens the force of the blow.

In all the bones there are canals, independent of the cellular
structure, which penetrate to a greater or less extent between
the lamina, and go in various directions, some longitudinal,
others oblique and transverse. These canals transmit the blood-
vessels, and were first pointed out with exactitude by Clopton
Havers, an English anatomist. But he assigned a wrong
application to them, as he believed that the marrow ran through
them, in order to make the bones supple, and to unite their
lamina more strongly. S. B. Albinus corrected the mistake, by
demonstrating that they were filled with blood-vessels. These
canals in a vertebra are particularly large, and open on the
posterior face of its body, by one or two large foramina. In
the cranium they are remarkably well seen ; but their discovery
is of more modern date. M. Portal says, that in the bones
each kind of vessel has a particular canal for itself alone ; those
of the arteries are therefore to be readily distinguished from
such as belong to the veins and to the nerves ; and this takes
place both in the large and in the small canals. Occasionally
the vessels dip into a common canal, but if any one will take
the trouble to follow them, he will find them ultimately
separating from each other.]

— The canals for the transmission of blood-vessels, which
exist in abundance in the compact bony tissue, cannot be well
seen in the healthy state, except by the aid of the microscope.
With the aid of this instrument they may be seen in great
numbers, running in a longitudinal direction, opening in its
internal or medullary cavity, so as to maintain a free commu-
nication between the vessels on the exterior, and those in the
cavity of the bone.

— When cut in surgical operations, blood issues from the
compact substance, which is also susceptible of inflammation
and its consequences like other vascular parts. In inflammation,

STRUCTURE OF THE BONES. 19

the compact portion, is sometimes seen swelled and expanded,
so as to develop in its substance, a cellular arrangement,
somewhat like that of the co'mmon spongy tissue. Maceration
of a bone in water, after its earthy part has been removed,
exhibits the same cellular structure. In fact, the principal
difference between these varieties of bony tissue, consists in
their difference of density, with some variation in the disposition
of their fibres ; the cells being condensed in the compact portion
so as to admit of a decrease in the diameter of the bones,
without a corresponding diminution of their strength. Hence
the amount of substance being the same, in the extremities and
shafts of the long bones, sections of equal length must of course
be of equal weight. —

— In structure bone is composed of lamellae, which are con-
centric in long and parallel in flat bones. Between the lamellae
run the vascular canals of the bones, and are lodged the bony
corpuscles, which have been lately discovered. See p. 46.
— In the firmness of their texture and their general aspect,
bones resemble inorganic matter, but they are nevertheless
highly organized. /c02

For example, if a bone be macerated in certain acid liquors, J
the earthy matter will be dissolved, and a membranous orj fj/%
cartilaginous substance will remain, resembling the bone inl
form and size.*

If the bones of a young subject, after being injected, be treated
in the same way, this membranous substance will appear to be
very vascular — when the injection has been successful, it will
appear uniformly reddened by the greatest number of vessels
which are filled with the matter of injection. These vessels
discharge blood when the periosteum is removed from the
surface of bones, in the living subject, and they also form
granulations upon bony surfaces that have been thus denuded.

— On the other hand if a recent bone be exposed for a
considerable time to the action of a moderate fire, or boiled for

* One part of muriatic acid to thirty of water is a good mixture for this
purpose, by taking care to keep up the strength of the mixture by additions of
the acid from time to time. — H.

20 STRUCTURE OF THE BONES.

a long period in a Papin's digester, the other element of the
bone may be obtained — its earthy structure — in a separate
state, representing the original perfectly, in size and shape. It
is then perfectly white, and is so light and brittle as to crumble
on the slightest touch.

— Exposure of bones for a long time to the action of the climate,
will cause it to shell off in layers and fall into powder, from the
same cause, the destruction of its animal matter.
— A bone macerated in acid, or well incinerated, may be torn
or split in particular directions, more readily than others, and
manifests an apparent fibrous arrangement.

*"" — In regard to the disposition and arrangement of these fibres,
anatomists differ, though it has been with them a subject of
much research. The length of each fibre is limited, running
but a small part of the length of the long bones, but is much
greater than its breadth and thickness. The greater part arc-
longitudinal, that is, run in the direction of the axis of the
bone ; some are transverse and some oblique. From the
shortness and varied direction of the fibres, and the cellular
appearance of the bone when macerated, Scarpa denied
entirely, the existence of a fibrous arrangement in the bones,
and considers them composed throughout, exclusively of
cellular substance, more or less compacted.
— Malpighi and Havers, believed the bones made up wholly of
concentric lamellae, -formed of fibres and filaments, encrusted
with osseous matter, laying over each other like the leaves of
a book. Gagliardi believed also, that these lamellae were united
together by little pins of the same material : some of which
were straight, some oblique, and some he fancied had round
heads. De Lasone says that these lamellae are made up of ossi-
fied fibres, united by oblique ones, and Reich el, that the lamellae
and fibres, form a porous tubulated tissue, continuous with
the spongy substance.* According to J. F. Meckel, the proper

* The opinions of these different anatomists are interesting mainly as con-
nected with the history of the science. The discrepancies existing between them,
may now readily be reconciled, since the true composition or structure of bone
has been rendered apparent by the use of the microscope. See page 46.— p.

STRUCTURE OF THE BONES. 21

substance of the bones, is of a fibro-laminated nature, the
fibres in some parts being so closely aggregated, as to form a
compact bone, and separated and expanded in others, so as to
constitute the cells of the spongy portion. The longitudinal
fibres are much the most numerous, one leaning against, and ter-
minating near the commencement of another, so as to give an
imperfect appearance of continuity throughout the bone.
These fibres at the extremities of the bones, are lost in the
spongy or cellular tissue which they assist to form. The
transverse and oblique,* serve to connect the longitudinal fibres
together, and are united with them uninterruptedly upon their
sides ; in the spongy portions, they appear also, to assist in the
formation of the cells. They are both most abundant in early
infancy, and as the bones increase in length, are directed more
in the axis of the bone, till the oblique seem nearly lost in the
longitudinal, and the transverse become more oblique.
— The fibres of the different layers of the compact bone, are
united to one another more intimately upon the sides, than to
the layers below, hence a bone exposed to the action of the
weather or the fire, shells off in scales, or in certain morbid
states during life, as necrosis, exfoliates in layers.f
— From these investigations the osseous tissue, may be justly
considered as formed of an animal or membranous basis, analo-
gous to the common cellular tissue and cellular fibre in other
parts of the body, and differing from them only in its being imbued
or incrusted with inorganic earthy matter, which gives it ^firm-
ness and strength, but at the. same time renders it liable to
fracture. The cells of the bones, like those of the cellular tissue ^|*.
of the soft parts of the body, are all imperfect, having openings
by which they communicate with one another, and may be all
readily injected, with any fluid sufficiently thin to run ; and if

*

* These represent the uniting pins of Gagliardi.

| Mr. Howship of England, from some recent microscopical observations on
the bones, has been led to support the opinion of Scarpa, that the ultimate tissue
of all the bones, is reticular or cellular. This is evidently true, in regard to the
ultimate analysis of bones, when the course of the fibres has been destroyed by
prolonged maceration, or by suppurative inflammation. — p.

CHEMICAL COMPOSITION OF THE BONES.

fluid mercury be used it will make its way through the vascular
foramina to the external surface. —

The existence of absorbent vessels, and even of nerves, in
bones, is equally certain with that of the blood-vessels, but they
are not easily demonstrated.

[The French anatomists have occasionally traced branches
of the fifth pair of nerves going along with the nutritious arte-
ries into some of the bones ; hut as yet no other nerves have
been seen by them. M. Portal speaks in familiar terms of the
existence of both nerves and lymphatics in the bones, as if he
had often noticed them ; he, however, has omitted to inform
us of the source, from which the former come.] fin the sound
state bones have no sensibility, but pain is often felt in them
when diseased. )

— We cannot doubt the existence of the absorbent vessels in
bones, since Cruikshank and Scemmering, affirm it from their
own observation, and from their own injections. Breschet, has
observed it many times, and Bonamy, in making a mercurial
injection of the inferior extremities, " was able to follow them
for some time in the interior of the osseous tissue."
— They possess (according to Bichat,) a certain degree of ex-
tensibility and retractility, which is developed so slowly as to
be almost insensible in its progress. These properties are de-
monstrated in the expansion of the bones of the facje, from
tumors of the antrum, and in the retraction of the sockets of
the teeth, after the loss or removal of the latter. —

Modern chemistry has ascertained that the earthy matter of
'bones is principally a phosphate of lime; carbonate of lime, in
a smaller quantity, is also found in them. These earthy sub-
stances compose near one-half of the weight of bones, and a
large proportion of the remainder appears to be gelatinous and
cartilaginous matter.

— The chemical composition of bones will be found to vary,
in the different ages of life, and in some measure according to
the individual bones selected for investigation ; the inner com-
pact plate or vitreous table of the cranial bones, and the petrous
portion of the temporal, possessing a greater relative amount

CHEMICAL COMPOSITION OF THE BONES. 23

of earthy matter than any other bones in the body. From
these causes, arises considerable discrepancy in the analysis
given by different chemists. In early life the relative propor-
tion of earthy matter is at its minimum, the animal at ijs max-
imum. In advanced age, the reverse holds good, when the
bones are notoriously brittle and liable to fracture. Diseased
conditions of the system are known to still further modify these
proportions : in childhood the earthy matter may be so much
diminished that the bones become plastic and yielding, as in
rickets ; and at later periods of life, it preponderates occasion-
ally so much over the animal as to render them liable to break
at the slightest shock, as in cases of fragilitas ossium ; and
in some of the venereal affections, the bones are rendered nearly
as solid and heavy as a piece of ebony.

— The earthy matter of the bones of the higher animals con-
sists chiefly of phosphate of lime, with carbonate of lime, and
a small quantity of phosphate of magnesia, and fluate of lime.
— The phosphate of lime of the bones is a subsalt, according to
Miiller, in which the base and acid are combined in peculiar
proportions, and which is always obtained when biphosphate
of lime is precipitated by an excess of ammonia. The phos-
phate of lime of the urine is a super-salt, held in solution ; in
the disease called mollities ossium, it seems to be excreted in
this state in the urine in larger quantity than natural. The
following is the result of Berzelius' analysis of the bones in man
and the ox :

Man. Ox.

Cartilage* completely soluble in water 32.17

VI 1 1Q < *3"30

Vessels - ... 1.13

Neutral phosphate of lime - - 51.04 55.45

Carbonate of lime 11.30 3.85

Fluate of lime - 2.00 2.90

Phosphate of magnesia 1.16 2.05

Soda with a small proportion of cloride of } 1 04*

sodium - -

100.00 100.00

* i. e. Gelatine.

24 RESEARCHES ON THE INTIMATE STRUCTURE OF BONE.

— Schreger states that in the bones of a child, the earthy
matter constitutes one-half, that, in the bones of an adult it
amounts to four-fifths, and in those of an old person to seven-
eighths of the whole mass.

— Fourcroy and Vauquelin, found no fluate of lime in their
analysis, but met with some iron, manganese, silex, alumine,
and phosphate of ammonia. The luminous appearance of
bones at night, when the animal matter is undergoing decom-
position, is believed to be owing to the phosphorus liberated
from combination ; and in such instances, Bichat has found an
oily or unctuous exudation at the luminous points.
— The observations of M. Gerdy* who has carefully investi-
gated the structure of the bones, coincide in a great degree
with the microscopical researches of the German anatomists
shortly to be noticed. He considers that there are four distinct
tissues in bone, which have been confounded together up
to this time ; the compact, the canaliculated,j* reticular, and
areolar or cellular.

— The compact tissue has in certain bones a fibrous appearance ;
its fibres appear longitudinal in long bones, radiated or irregu-
larly divergent in many of the flat. The whole of this fibrous
appearance is illusory, as Scarpa asserted, and is owing to the
grooves or canals in the compact portion of the bones which
lodge vessels, (canals of Havers,) run longitudinally in the
compact portion, and have orifices leading into them from the
outer surface ; between the canals is found projecting the pro-
per structure of the bone, which is necessarily thin, and from
the great number of these vessels, presents the appearance of
fibres. The vascular openings leading into the grooves, are
some perpendicular, and some oblique in regard to the surface
of the bones. They all conduct vessels into the compact tissue.
The compact tissue, as will be better seen under the head of
formation of bone, is primitively a compound of osseous tubes
developed around the vessels. These osseous tubes which are
longitudinal in the long bones and radiated in the flat, are so

* Bulletin de Clinique, 1835-6.

f The canaliculated tissue is formed by the canals of Havers, which lodge
blood-vessels.

GERDY ON THE INTIMATE STRUCTURE OF BONE. 25

numerous, fine, so closely compressed together and so adherent,
that their arrangement has escaped the observation of anato-
mists. The existence of these vessels in the forming bone is
well understood, and they have been injected with mercury by
Tiedemann in the parietal bone,* In the adult healthy bone,
they are more difficult of detection, in consequence of *the dense
nature of the compact substance, in which the vascular chan-
nels of the bones and the vascular orifices on the surface are
reduced nearly to a microscopical size. But when the bony
tissue is diseased or inflamed, as in fractures or after amputa-
tions, their existence is no longer doubtful. Blood issues from
them when cut, and the vascular orifices on the surface, as
well as the canals in the compact tissue are visible to the naked
eye, and in some instances are said to have been Fig. l.f
as large as a pigeon's quill. Fig. 1, is a view
of these canals, as seen in a bone twenty-five
days after amputation. When the orifices and
canals are thus expanded, the compact tissue
appears rarefied, rough on its surface, more
light and fragile and corresponds in appearance
with the canaliculated tissue of Gerdy.
— The absence of fibrous appearance on the thick and mixed f
bones is dependent upon the direction of the canals, none of
which run parallel to the surface, but are all directed towards
the articular surfaces of the bones. In the foetus at birth the
compact portion of these bones appears sieve-like, from the
number of vascular orifices on the surface, which lead perpen-
dicularly to the canals that run towards the centre of the bones.
Hence, according to Gerdy, the compact layer of these bones,
is made up of minute bony rings, surrounding the numerous

* See Breschet, plates of the Venous System. — p.

f Fig. 1. Section of the extremity of the os femoris, twenty-five days after
amputation. It appears cribriform from the number of irregular orifices, be-
longing to the canals of Havers (canaliculi,) in. the compact portion of the bone.
The vessels which occupy these canals, are greatly enlarged by inflammation.
Cases of this sort have been confounded by writers, with inflammation of the
veins of the bones. — p.

\ The mixed bones are those which are mixed in their character ; being partly
short and partly flat, as, the sacrum, the temporal, maxillary bones, &c.

3

GERDY ON THE INTIMATE STRUCTURE OF BONE.

vascular orifices which touch each other at their circumference
like the rings round the orifices of a tin colander.*
— The canaliculated tissue, is developed in all the bones of
the body, but is least evident in the flat. It is an assemblage

of small canals traversed by
vessels, and has heretofore
been described as a part of
the cellular or spongy. In
the long bones it is found on
the inner surface of the com-
pact tissue, and separated
from the reticulated tissue of
the medullary canal, by a
parchment-like lamin, pierced
with holes for the passage of
anastomosing vessels. These
canaliculi form elongated cavi-
ties, which are slightly tor-
tuous, nearly parallel with
one another, not exactly
rounded, and have their pa-
rietes pierced with holes to
admit of anastomosis be-
tween the vessels which line
them ; they run in the long
bones in the direction of their
length, and in the thick bones,
from one articular surface to
the other. They arise in part 6

Fig. 2.f

* This we shall find is the opinion of the microscopists in regard to the struc-
ture of all compact bony layers. —

f Fig. 2. Vertical section of the inferior third of the tibia. 1. 1. Compact
tissue of the body of the bone, becoming gradually thinner towards the inferior
extremity. 2. 2. Reticulated tissue in the lower part of the medullary cavity
occupying the axis of the cylinder of bone. 3. 3. Canaliculated tissue, the vas-
cular canals of which deiach themselves successively from the compact walls of
the bone, and run nearly parallel with each other towards the extremity of the
bone. 4. 4. Cellular tissue of the epiphysis, composed of interrupted canaliculi,
and of tubular cells, which terminate nearly perpendicularly upon the articular
surface. 6. 6. The articular or sub-cartilaginous compact tissue, extremely thin.

GERDY ON THE INTIMATE STRUCTURE OF BONE. 27

from the divisions of the nutritious foramina, which transmit
the medullary vessels of the long bones, but chiefly from the
vascular (Haversian,) canals of the compact tissue, as seen in
a vertical section of the femur and tibia, fig. 2 and fig. >J. where
the increase of the canaliculated structure is in inverse propor-
tion to the thickness of the compact. These canals unite together,
and divide again and again, so that they become increasingly
numerous as they approach the spongy extremities, when they
separate from each other and spread out so as to form a large
part of these extremities.

— The cellular or areolar tissue of Gerdy, is formed in the
thick bones and the extremities of the long bones by the inter-
ruptions of the canaliculated tissue, by other canals arising from
the surface of the bone which cross them in an angular direc-
tion, so as to form quadrilateral cells, see Fig. 3, No. 1, the par-
titions of which are pierced, so that there is a free communica-
tion between the vessels lining the different cells.
— The reticulated tissue which was confounded by Bichat with
the canaliculated, should be now as it was before his time dis-
tinguished from it. So far from being formed of a canaliculated
tissue for the purpose of containing vessels, it consists only of
a network of bony filaments for the purpose of supporting a
delicate cellular membrane called the medullary which is
thrown into the form of cells to retain the fat or marrow, and
which is very vascular. It is found chiefly in the cavities of
the long bones, and terminates short of the extremities in a
point, see Fig. 3, 6, while the canaliculated tissue continues to
expand. This tissue is beautifully developed in the long bones
of the horse, but scarcely exists at all in those of the bullock.
- — Vessels of the bones. All anatomists admit three kinds of
vessels in the bones ; those of the compact tissue, those of the
cellular tissue, those of the medullary canal.
— Those of the compact tissue are very fine and very nume-
rous ; they, penetrate it in great numbers, after having divided

Very generally it is deficient in places on the articular surface of bones, so as to
leave the cells of the spongy tissue and their vascular canals naked when the
cartilage is removed. 7. Internal malleolus. — p.

28 GERDY ON THE INTIMATE STRUCTURE OF BONE.

Fig. 3.*

to capillary minuteness in the periosteum. The diameter of
these little vessels, where they enter the bone, has been calcu-
lated to be about one-twentieth part of a line. The drops of
blood which collect when the periosteum is stripped from the

* Fig. 3. Vertical section of the os femoris. 1. 1. Tubular cells perpendicular
to the articular surface of the bone ; sometimes these cells are chiefly round.

2. Cartilaginous lamin separating the epiphysis from the shaft of the bone.

3. Vertical canal opening by one or more foramina, in the fossa at the top of the
trochanter, and anastomosing with the canals of the canaliculated tissue. It
lodges one of the vessels of the cellular tissue ; which penetrate by the extremity
of the body of the long bone. 4. 4. Vascular canaliculi, which run obliquely
upwards and inwards towards the lamen of the epiphysis, where the cartilage
begins to be removed, and the consolidation of the epiphysis and shaft has com-
menced. 5. 5. Canaliculi of the upper part of the body of the bone, which are
directed towards the axis of the bone, and which anastomose with the vascular
canal indicated at 3. 6. Conical termination of the reticulated tissue of the
medullary canal. — p.

GERDY ON THE INTIMATE STRUCTURE OF BONE. 29

recent bone, indicate the position of these vessels. Having
entered the compact tissue, they spread in its channels (canals
of Havers, canaliculi of Gerdy^) which are imperceptible
without a microscope in a healthy bone, but beconae, very
manifest in disease.

— Those of the medullary canal enter usually by a single large
foramen, give off some branches to the canaliculi in their course,
and having reached the medullary or central cavity, divide into
two branches, which run in opposite directions towards the
extremities of the bone. These branches divide and subdivide
very minutely in the medullary membrane, and anastomose
very freely with the vessels of the canaliculated tissue upon
the side, and in the adult, (after the cartilage which separates
the epiphysis from the body of the bone has been removed,)
with the cellular tissue of the extremities.

— Those of the cellular tissue, that is to say the vessels of the
extremities of the long bones and the large vessels of the other
bones, penetrate from the surface by foramina much larger than
those of the compact bone, and occasionally under the form of
distinct canals. They are very numerous. I have counted 145
on the lower end of the femor, 25 upon a vertebra, and. 30 on the
os calsis. They anastomose intimately with the other two orders
of vessels, and are particularly abundant near the articular sur-
face of the bones, where they form the tubular cells, and as some
suppose, directly or indirectly assist in the formation of the
articular cartilages, which many have considered a simple pro-
duct of excretion like the nails or hair. All the vessels are sur-
rounded in the canals by a cellular tissue, more or less delicate
loose and filled up with a fatty or oily matter, which is least
abundant in the compact tissue where the canals are very small.
No other nerves except those which accompany these vessels
are believed to enter the substance of bone. These facts in
regard to the structure of bone are supported both by observa-
tion and reasoning. The microscope shows us thousands of
vessels in the healthy state entering into the substance of the
bones. Inflammation attended with vascular congestion develops
and renders them so obvious as to be appreciated by the
3*

30 DEUTSCH AND MIESCHER

unassisted eye, the slightest irritation with a probe will
cause them to bleed freely, and heat applied to a section of a
recent bone, will develop the fatty or oily matter even in the
compact portion. From the complexity of their organization,
and the frequency and importance of their diseases, bones demand
from the student, more earnest study, at least in regard to
their general anatomy than is usually given. —
— Deutsch,* under the direction of Purkinje, and Miescherf of
Berlin whose investigations were made prior to those of Gerdy,
have arrived at nearly similar conclusions in regard to the
structure of bone. In very thin transverse sections of long
bones, which had been macerated in dilute acid, they disco-
vered the circular orifices of the longitudinal canals in the com-
pact portions of the bone ; and in thin longitudinal sections
the canals were seen divided in the direction of their length. (See
Figs. 4 and 5.) The canals, according to these observers, com-
municate here and there with each other, and constitute the
longitudinal and transverse canals of Havers, and which are
described by Lewenhceck, as his third and fourth kinds of

pores.

Fig. 4.J

— These canals are rilled with yellowish medullary or adipose
matter, in which according to Miescher, are seen many minute
capillary vessels, when successfully injected after the method
of Krause.

* De pentiori ossium stractura observations. Vratislavise, 1834.

f De ossium genesi, structura et vita. Berolini, 1836.

$ Fig. 4. Is a longitudinal section of a long bone, magnified one hundred
times, a. One of the longitudinal canals not fully exposed, b. b. Longitudinal
canals, c. c. These canals partially cut across, so as to exhibit the concentric
lamellae which surround each one. d. d. Transverse canals joining the others.
The straight lines near the margins of the cut, are the lamellae divided in the
direction of their length, which surround the canals. The spots seen are the
bony corpuscles, not sufficiently magnified to render them distinct.

ON THE INTIMATE STRUCTURE OF BONE. 31

Fig. 5.*

— In the transverse section, each of the orifices of the canals,
Fig. 5, is seen surrounded by ten or fifteen concentric lines,
which on examining the longitudinal section, Fig. 4, are found
to be as many lamellae running the whole length of the canal,
and each about the ?|5th part of an inch in diameter, accord-
ing to the microscopical measurement of Deutsch.f The spaces
in the transverse section of the bone, not occupied by the lon-
gitudinal canals and their concentric lamellae, are filled by
other lamellae, which form larger concentric rings round the
great medullary cavity. The diameter of the canals of Havers,
according to Miescher, varies from ^th to ^ili of an Eng-
lish inch.

— In the flat bones the canals with their lamella, run parallel
with the surface of the bone. In the long bones, the longitu-
dinal canals are directed obliquely into the central cavity.
— In the lamellae concentric to the canals, there is an appear-
ance of dots or short lines, which do not occupy the whole

* Fig. 5. Is a transverse section of one of the flat bones of the cranium, mag-
nified one hundred times, a. Compact substance or table of bone, expanding
into diploe. b. b. c. c. Vasculo-medullary canals of the compact portion, cut
across, d. Transverse communicating canals, between these and the larger
canals or cellular cavities of the diploe. e. Diploic cells communicating with
others at /. Diploic cells like the canals of the compact portion, are surrounded
with concentric striae or lamellae, and are in fact only amplified vasculo-medul-
lary canals. The spots upon the surface, are the bony corpuscles.

f Some modern observers have made the diameter or thickness of each of
these lamellae, much less than that stated by Deutsch. Mr. Wilson states it to
be not more than the ^5^ a measurement which appears to me to err much
on the minimum side — .

32 OF THE PERIOSTEUM.

thickness of each lamellae, and which Deutsch, supposed to be
extremely minute tubes. Some of these dots or lines, see Fig.
5, appear to transverse more than one lamella, though the
majority, as Miescher describes them, are very short, and
appear like the separations between the granules of the carti-
lage of the bones, from which the calcerous portions had been
removed.* The result of the observations of Miescher, is :
— 1st. That the spongy structure of bones, is nothing but an
amplification of the canaliculi, as is shown by Gerdy.
— 2d. That the medullary canal, as shown by its formation
and name, is provided for the purpose of union or anastomosis,
between these enlarged canaliculi, and,

— 3d. That therefore, the canaliculi, girdled with concentric
lamellae and containing a medulla, composed of a great body
of vessels, is the primary element or form of the osseous tissue,
which is subsequently more fully developed.
— Scarpa is therefore correct in saying that the solid parts of
bone, are formed of the cellular structure in a more compacted
state. The reticulated tissue, which forms a sort of link
between the cellular substance and the medullary cavity, and
the osseous filaments which project every where from the
parieties of the cavity into the medulla, are the remains of the
walls of the cells, the integrity of which is impaired in conse-
quence of the enlargement of the orifices by which they com-
municate together. —

Of the Periosteum.

Bones are invested with a firm membrane .denominated
periosteum, which is of a fibrous texture, and in some places
may be separated into different lamina. The external surface
of periosteum is connected with the contiguous parts by cel-
lular membrane ; the internal surface is connected with the
bone by a great number of fibres and blood-vessels. The
orifices of these vessels become apparent, when the periosteum
is separated from bones in the living subject.

* Subsequent microscopical observations, as will be shown further on, have
confirmed this supposition of Deutsch. — p.

MEDULLARY MEMBRANE OR INTERNAL PERIOSTEUM. 33

This membrane covers the whole bony surface, except those
parts which are invested by cartilages, and the capsular liga-
ments of joints, those which are occupied by the insertion of
tendons and ligaments, and the bodies of the teeth. It appears
most intimately connected with the surfaces of spongy oones,
and the extremities of the long bones. In a sound state it has
very little sensibility ; but in some cases of disease it appears to
be very sensible ; of course it must be supplied with nerves,
although several expert anatomists have declared they could not
trace them.

It is probable that the principal use of the periosteum is to
transmit vessels to the bones for their nourishment ; but death or
exfoliation of the surface, does not always take place when the
periosteum is removed from a portion of bone.*
— This membrane presents a polished, pearly white appear-
ance, when examined in the recent bone. It has received
different names according to the parts which it covers, though
its structure is nearly uniform throughout. Thus, when it
covers the exterior surface of the bones of the cranium it is
called pericranium ; when it covers the cartilages, perichon-
drium ; and when it covers the bones with the exception of
those of the head, periosteum.

— In infancy the periosteum is soft, thick, and spongy, and
may be readily separated from the bones. In adult life it is
more firm and compact, and is often so intimately united to the
bones as to be detached with difficulty from them. In old age
it is extremely dense, and becomes not unfrequently ossified at
its internal surface. Its vascularity, which is at first rather
obscure, also gradually increases as life advances, but in old age
it again diminishes.f

Of the Internal Periosteum or Medullary Membrane.
— This membrane is particularly well marked in the cavities

* Dr. Physick thinks that the periosteum frequently prevents the bones from
participating in contiguous disease, as the pleura turns off an abscess inthe parie-
tes of the thorax from its cavity, or the peritoneum from the cavity of the
abdomen. — 11.

f Anat. Phys. and Diseases of Bones and Joints. By S. D. Gross, M. D.

34 MEDULLARY MEMBRANE OR INTERNAL PERIOSTEUM.

of the long bones, where it forms a thin, delicate, pellucid,
vascular membrane, lining the sides of the cavities of the reticu-
lated tissue, in which it forms vesicles, that contain the marrow.
— The lining membrane of the cells in the spongy portion of
the bones is still more delicate in its structure, and more difficult
of demonstration, and has been supposed by many anatomists
to be formed only from the coats of the blood-vessels which
anastomose thousands of times with each other in the interior
of these bones. Its office, however, is precisely similar to that
of the membrane in the cavity of the long bones, to lodge the
fatty or medullary matter which is furnished by exhalation.
It is very inflammable/ burning with a beautiful blue tinge, and
an oily disagreeable odor, fluid during life, but presents itself
after death, under the form of brilliant granules of solid fatty
matter. When death has taken place from some wasting
disease as dropsy or consumption, the fat is removed by
absorption, and its place is supplied by a watery fluid which
renders the bones less greasy and more valuable as cabinet
preparations. This medullary substance as has been before
observed is also found with the vessels in the canals of the com-
pact portions of bone< —

At the extremities of the long bones, the formina for the
transmission of the blood-vessels and fibres are much larger
than they are in the middle ; but there is an oblique canal near
the middle of these bones, which transmits vessels to this
membrane in the interior of the bones called nutritious or
medullary.

The surface of the internal cavities and cells of bones it will
then be seen, is lined by a membrane more delicate and more
vascular than the periosteum, which contains the medullary
matter that is always found in their cavities. [This is the*
internal periosteum or the medullary membrane of the bones.
M. Portal denies that it exists as a distinct membranous sac,
but asserts, that it is derived from the envelop of the vessels
which is sent in along with them from the periosteum.]

It has been said that in some circumstances this membrane
has had great sensibility, but the- reverse is the case in com-
mon.

MEDULLARY MEMBRANE OR INTERNAL PERIOSTEUM. 35

The medullary matter in the large cavities of bones has a
strong resemblance to adeps. That which is in the cells, at the
ends of the long bones, appears more fluid. In young animals
it is slightly tinged with a red color. *s

— The chemical properties of the adipose or medullary sub-
stance of the bones consist according to Berzelius of the fol-
lowing ingredients :

Pure adeps or marrow 96

Membrane and blood-vessels - 1

Albumen -

Gelatine

Extractive and peculiar matter

Water

100

— The character of this substance differs somewhat at the dif-
ferent stages of life ; it is of a thin aqueous consistence and of
a reddish color in the infant ; of the consistence and presenting
after death somewhat the appearance of butter in the central
cavities of the bones, and of a red semi-fluid appearance in the
spongy tissue of the bones of the adult ; in old age it has some-
thing of a rancid smell, and is of a deep yellow color. The
adeps of the bones was supposed at one time to contribute to
the flexibility, tenacity, and nourishment of the Irenes, but it is
now generally believed to be deposited upon the same principles,
as fat in other parts of the body, when nutritive matter is super-
abundantly elaborated by the digestive organs, and is held in
reversion, as an aliment for the future wants of the economy,
during temporary inanition from sickness or other causes.
— The deposit of fat in bones is not universal among animals.
In birds the central cavity of the long bones, is filled only with
air which is introduced into them from the lungs, and serves !
greatly to diminish their specific gravity, and facilitates their/
evolutions in the atmosphere.

— It is found in great quantity in the bones of the head of the
wwerocep/m/ws, or sperm whale, far out of the pro-

36 CARTILAGES AND THEIR STRUCTURE.

portion required, if its object only was that of nourishing the
bones.

— Its purpose in this animal, besides being a deposit of aliment
in reserve, is believed to be that of buoying up its head to ena-
ble it to respire with greater freedom. —

Cartilages and their Structure.

CARTILAGES are white elastic substances, much softer than
bones, in consequence of a smaller quantity of earth entering
into their composition.

Their structure is not so evidently fibrous as that of bones ;
yet by long maceration, or by tearing them asunder, a fibrous
disposition is perceptible.

In articular cartilages their fibres are parallel to each other,
and directed towards the cavities of the respective joints.

Their vessels are extremely small, though they can be readily
injected in cartilages where bone is beginning to form. The
vessels of the cartilages of the joints, however, seem entirely to
exclude the red blood ; no anatomist having yet been able to
inject them. They have no cancelli, nor internal membranes,
for lodging marrow ; no nerves can be traced into them ; nor do
they possess any sensibility in the sound state.

Upon their surface, there is a thin membrane termed peri-
chondrium, which in cartilages supplying the place of bone, as
in those of the ribs or at the ends of long bones in children, is
a continuation of the periosteum, and serves the same general
purposes to cartilage as this does to bone.

Upon the surface of articular cartilages, the perichondrium is
a reflection of the inner surface of the capsular ligament, and is
so very thin, and adheres so closely, as to appear like part of
the cartilage itself.*

One set of cartilages supplies the place of bone, and by their
flexibility admit of a certain degree of motion, while their

* The articular cartilages are the only ones not provided with a fibrous peri-
chondrium. The synovial membrane which is supposed to cover them by being
reflected from the inner face of the capsular ligament, is said to supply the place
of perichondrium. — p.

CARTILAGES AND THEIR STRUCTURE. 37

elasticity recovers their natural position, as in the nose, larynx,
cartilages of the ribs, &c.

Another set, in children, supplies the place of bone, until bone
can be formed, and affords a nidus for the osseous fibres <p shoot
into, as in the long bones of children.

A third set, and that the most extensive, by the smoothness
and lubrication of their surface, allow the bones to move readily,
without any abrasion, as in the cartilages of the joints.

A fourth set supplies the office both of cartilage and ligament,
giving the elasticity of the former and the flexibility of the
latter, as in the bones of the spine and pelvis.

— Next to the bones, the cartilages form the hardest tissue in
the body. On first inspection they do not appear to present
any sort of internal organization. They appear homogenous
in their texture and inorganic. When more carefully inspected,
however, and especially in the articular cartilages, a particular
structure is apparent.

— According to De Lasone and Hunter, the articular cartilages
are composed of fibres implanted perpendicularly to the surface
of the bones, and parallel with each other, like the villior threads
upon a piece of velvet. In this manner the cartilages covering
the bones forming the joints, supposed to be invested with
the synovial membrane, rub against each other, not upon the
sides, but upon the ends of the fibres, which brings the elas-
ticity of the latter into play. The perpendicular direction of
these fibres may be made apparent by maceration, or by
sawing down a recent bone, and splitting through its carti-
lage— and they were believed by Beclard, to constitute the
numerous free floating flocculi, which are seen on the surface
of cartilage in its transformations from disease.
— It is very probable that there is some cellular tissue in the
composition of cartilages : when carefully incinerated, the re-
mains present a cellulated appearance. Its existence is rendered
still more probable, from the cartilages being developed in the
foetus in a mould of cellular tissue ; and from fleshy granulations,
having been seen occasionally to spring from the surface of some
4

x ^

.• % ,* i:% * «.. . fr • %%%'":> . \--\X\

7SX-- 0V.

•% . . /

38 CARTILAGES AND THEIR STRUCTURE.

of them in various parts of the body, though not from the ar-
ticular.

— When a recent cartilage is cut, a whitish juicy fluid is seen to
exude from its substance, which must get into it, by imbibition
from the surrounding parts, or as has been thought more proba-
ble, be carried into it, by white vessels, too small to admit more
than the serous portions of the blood. If inflammation take place,
which is admitted in many carlilages, though not as yet proven
to exist in those of the joints, it differs from ordinary inflam-
mation as these vessels are never so dilated, as to admit the
red globules, and present a red appearance. No lymphatics
have ever been traced into them, though Mascagni was
disposed to consider them as formed entirely of these vessels.
Nor have nerves been found in them, the very existence of
which in these parts, though so necessary to the perfection of
other organs, would have unfitted them for their office. Hence
we find them smooth, so as to move upon one another without
friction, destitute of nerves, so as to bear pressure without sen-
sation, and feebly supplied with vessels, so as to be little prone
to inflammation, if they be not, as Gerdy has suggested, a mere
secretion like the hair and .nails. Hence they are enabled to
bear exposure to the air for a considerable time without
change, as stated by Velpeau, and to exist unharmed frequently
in the midst of gangrene.

— According to J. Davy, their chemical composition is 55. parts
in the hundred of water, 44.5, of albumine, and .5 of phosphate
of lime. As in the bones, however, the chemical proportions
vary at the different periods of life. They are nearly fluid in
the foetus, contain a large amount of fluid in youth, have the
proportions given above at puberty, and a much larger amount
of earthy matter in old age. In fact, with some few exceptions
in the joints, they all have a natural tendency to ossify as life
advances.

— The structure of cartilage is, however, not fully understood ; that
they share in some manner in the general circulation of the body,
is rendered probable by their being colored yellow in jaundice ;
and that they are not reddened like the bones when an animal is

HO ....... • ---in

ACCIDENTAL DEVELOPMENT OF CARTILAGES. 39

fed upon madder, is said by Beclard, to be owing to tbe small
quantity of phosphate of lime which they contain, and with
which this coloring matter only has affinity. They participate
too in the ulcerative process in many parts of the body, as in
those of the nose, and as I have many times seen, in tnose of
the larynx and trachea.

— All cartilages are divided into two classes, temporary or
ossescent, and permanent, a distinction which though not per-
fectly exact, is nevertheless very convenient for the purposes
of study. The temporary cartilages, (cartilag. temporaries)
are those employed in the development of the bones, those of
which the models of the bones are all formed in the foetus, and
which gradually as the infant advances in growth give place to
bony matter. The substitution of bony matter for the cartilagi-
nous, is completed about the period of puberty.
— The permanent cartilages (cartilag. permanentes) are devel-
oped at an early period of life like the former, but have little
tendency to undergo ossification, and retain their cartilaginous
character for the whole or the greatest part of life. These com-
prise, the articular and costal cartilages, those of the larynx,
eustachian tube, auditory meatus, etc. Some of these have a
stronger tendency than the rest to ossify, as those of the larynx
and ribs, which are frequently found after the fortieth year of
life, converted into bone.

Accidental development of Cartilages.

— In almost every one of the different tissues of the body, car-
tilages have been occasionally met with, but in general only after
the middle period of life, when from their having apparently
no fixed laws of development, they have been called acci-
dental.

— 1st. They are found in the form of plates of greater or less
size, adherent by both surfaces to the membranes between
which they are formed ; in the arteries, where these plates are
most frequently met with, they are attached on their inner
surface to the serous lining membrane, and on their outer to the
middle coat of the vessel.

40 FORMATION OF BONE.

— 2d. They are frequently met with in the form of roundish or
irregular masses in the substance of the different organs, as the
arteries, lungs and ovaries.

— 3d. Under the form of smooth flattened concretions, formed
originally according to Meckel on the outer side of the synovial
membrane of the joints, and which develop themselves towards
the centre of the cavity of the joints, till their attachment to
the membrane is stretched out, so that it becomes a mere pedicle,
which not unfrequently breaks *off. In this way is formed the
loose cartilages often met with in the knee joint.
——All these accidentally developed cartilages have a tendency
to be converted into bone, and which are then called accidental
ossifications. —

Of the Formation of Bone.

The generality of bones, and particularly those which are
long, are originally formed in cartilage ; some, as those of the
skull, are formed between membranes, and the teeth in distinct
bags.

When ossification is about to begin in a particular part of
a cartilage, most frequently in the centre, the arteries, which
were formerly transparent, become dilated, and receive the red
blood from which the osseous matter is secreted. This matter
retains, for some time, the form of the vessels which gave it
origin, till more arteries being by degrees dilated, and more
osseous matter deposited, the bone at length attains its com-
plete form.

During the progress of ossification, the surrounding cartilage
by degrees disappears ; not by being changed into bone, but
by an absorption of its parts, the new-formed bone occupying
its place.

The ossification of broad bones, as those of the head, begins
by one or more points, from which the osseous fibres issue in
rays, as seen in Fig. 6.

The ossification of long bones, as in those of the extremities,
begins by central rings, from which the fibres extend towards
the ends of the bones.

FORMATION OF BONE. 41

The ossification of spheri-formed bones, Fig. 6.*
begins by one nucleus, as in the wrist ; and
that of irregularly shaped bones by different
nuclei, as in the vertebrae.

Some bones are completely formed at the
time of birth, as the small bones of the ear.

The generality of bones are incomplete
until the age of puberty, or between the fifteenth and twentieth
year, and in some few instances until a later period.

In children, many parts of bones, particularly the ends of
long bones, are distinct from the bodies ; they are called
epiphyses, and can be readily separated from the bodies of
bones, by boiling, or by maceration in water.

The epiphyses begin to appear after the body of the bone is
ossified, and are themselves ossified at seven or eight years of ,'
age, though their external surface is still somewhat cartilagi-
nous.

They are joined to the body of the bone by the cartilages,
which are thick in children, but gradually become thinner as
ossification advances, till at last, in the adult, the external
marks of division are not to be seen, though frequently some
mark of distinction may be observed in the cancelli.
— The development of bones is the final result of several suc-
cessive changes. In the foetus the bone is at first represented,
by a soft gelatinous mass, continuous throughout as one piece,
and in which there is no appearance of joints. The consistence
of this matter gradually increases, and presents a cartilaginous
appearance, about the second or third months of foetal life. At
the same period a separation is manifested at the place of the
joints. A third change takes place in the cartilage, which is
that of ossification ; this commences in some of the bones,
between the second and third months of foetal life, at various

* Parietal boss of the infant at birth magnified, showing the central point of
ossification. At first sight the vascular canals, resemble radiated lines, but with
a little attention, they will be found to be vascular channels, slightly tortuous,
and originating near the centre of the boss or protuberance from the foramina
in Ihe newly formed bone. — p.

4*

42 FORMATION OF BONE.

periods in other bones, in many not till long after birth, and is
not completed in all the bones of the body till near the period
of puberty.

•""" In the metamorphosis of cartilage to bone, the white and
homogeneous cartilagd which forms the mould of the bone,
becomes hollowed out so as to present irregular cavities,*
which subsequently form canals lined by a vascular membrane
and filled with a viscous fluid "which extend to the centre of
its structure. One of these canals forms subsequently the
nutritious foramen. The cartilage becomes opaque and
yellowish round this spot, the vessels convey red blood,
numerous red points are formed in the structure, and ossification
commences at the centre of the bone ; never upon the surface.
In the long bones a bony ring is first formed in the centre, and
the vascular canals extend themselves in the direction of the
extremities — in the flat and thick bones, in radii, attended by a
redness in the cartilage, nearest the seat of ossification, and a
diffused yellowness beyond it. From these canals the ossific
material is deposited, and the central point of ossification
grows, till the bone is completed. As the bony portion
advances in growth, its redness diminishes, and the vascular
canals which are at first la^e, decrease in size, so as to become
in the adult bone microscopical. The ossescent or provisional
cartilage of the bone, is solid and has in no instance any cavity
in its centre. The ring of bone which, as before observed, is
the first step of development in the long bones, has a cavity
in its centre which is subsequently destined to lodge the
medulla. In the flat bones, and especially those of the cranium,
ossification commences between the second and third months
of foetal life. Those of the cranium are formed between the
pericranium and dura mater, and their cartilaginous mould is
so thin and soft, that Howship and Beclard have denied its
existence. The vascularity commences in them at a central

* According to the German anatomists, see page 44, the hollowing of these
canals, is produced by an aggregation of the cartilaginous corpuscles into a series
of linear ranges, between which the vessels shoot that convey the earthy mate-
rial of the bone. — p.

GROWTH OF BONE. 43

point, and the ossificrays pass off in a straight direction, as seen
in Fig. 6, page 41.

— Many of these bones, as well as of those in other parts of
the body, are of such irregular shape, as to be inca]>able of
being formed of fibres radiating from a single centre ; they are,
therefore, developed from several centres, the rays of which
finally meet and inosculate. The development of the thick
bones, and the epiphysis of the long bones, take place in accord-
ance with the same laws.

— Growth of Bones. In all the long bones, the extremities or
epiphyses, are developed in separate pieces and between them
and the ossified shaft there is a cartilaginous lamen, which does
not disappear till the bone has attained its full development.
The bones increase in length by the continuous deposit of new
ossific matter in this lamen of cartilage, which seems retained
there as a soft bed for that purpose. As soon as the bone has
attained its full length at puberty, the lamen disappears, and
the epiphysis and shaft are consolidated, as seen in Fig. 3, where
2 is the layer of the cartilage, beginning to disappear at one
point. The long bones increase in diameter, by the successive
addition of new bony matter between the periosteum and bone.
It is said to be deposited from the periosteum itself: but that
opinion is incorrect, for no membrane can form a tissue, so
much at variance with its own structure. It is the blood-
vessels which merely ramify minutely through the periosteum,
that deposit the matter upon the surface of the bone, precisely
as they do in the centre. This mode of growth in diameter by
concentric circles, has been proved by experiments made with
mixing madder at intervals in the food of animals, by Duha-
mil,* Hunter, Professors Homer, Mussey, myself, and others.
On killing the animals, red rings were found surrounding the
bones, alternated with white ones corresponding to the periods of

* Duharail who was no anatomist, considered the growth of bones, as analo-
gous to the vegetation of plants. He placed a silver ring upon the bone of a
young animal, which he afterwards fed interruptedly on madder. The white
and red strata alternately covering the ring as he found on killing the animal,
he erroneously considered not deposited on the outer surface, but formed by the
expansion of the bone bulging over it as takes place in plants. — r.

44 OSSEOUS CORPUSCLES.

administering or suspending the madder.* At the same time,
that there is this increase of matter on the surface, there is a
corresponding enlargement in the central or medullary cavity,
which is said to be effected by the action of the absorbents.
It appears to me, however, to be far more likely due to an
interstitial growth, by which the walls of the cavity are in-
creased in dimensions and the cavity itself necessarily enlarged.
— Corpuscles. Purkinje has -recently Fig. 7.f

discovered in cartilage generally, and
especially in the cartilage of bone, round-
ed corpuscles, which are much larger
in diameter than the transverse sections
of the canals described in p. 30. The
existence of these corpuscles, has also
been confirmed by the microscopical re-
searches of Deutsch, Miescher, Sharpey
and others ; according to Miescher they
correspond with the brown spots described
by Lewenhoeck as his second order of foramina. In bone de-
prived of its earthy parts by maceration in acid, their appear-
ance is that of small brown spots,{ pellucid in the centre, and
surrounded with a distinct opaque line, which by a high magni-
fying power, appeared to Miescher to be denticulated. They
are situated between their lamellae, the long diameter being ob-

* Rutherford, of Edinburgh, first explained this coloring of the bone, without
that of the other tissues, by the affinity of the madder for the phosphate of litne,
upon which it acted as a mordant. — p.

f Fig. 7, is a representation from Miescher of the progress of ossification,
caused by inflammation in an adult bone, which takes place nearly in the same
manner that new bone is formed ; a a, the cartilage, the first stage in the forma-
tion of bone, and the small bodies thickly interspersed through it are the carti-
lage corpuscles of Purkinje j b b, the first or primary stage of the bony structure,
in which the osseous corpuscles arrange themselves somewhat into lines, and
the bony fibres shoot in between them, and in the thickness of the corpuscles
themselves saline particles are deposited, which renders them opaque ; c c, the
new structure completely ossified.

$ These as shown p. 46, are now believed to be new bodies, bony corpuscles,
which supplant the cartilaginous corpuscles of Purkinje. The above account
is retained in order to show progressively the history of the discovery.

NEW VIEWS OF THE GROWTH OF BONES. 45

lique in regard to the direction of the lamellae, and when the
work of ossification has not commenced, appear to have no fixed
arrangement, and are wedge-shaped, oval, oblong, or flattened,
see Fig. 8. Of the nature of these corpuscles, little f is posi-
tively known. Neither vegetable or mineral acids have any
effect upon them, except to render them a little more prominent
on the surface of a section of cartilage. Alcohol, ether, or a
cold solution of caustic potash does not change them ; but if
exposed to a hot caustic solution, or a long time macerated in
water they become completely liquified.

— The size of the corpuscles according to the measurements of
Miescher, varied in length from the 0.0048 to the 0.0072 parts
of a line, and in breadth from the 0.0017 to the 0.0030.* The
researches of this anatomist, of Miiller, and other recent ob-
servers, have shown that the formation of cartilage always
precedes that of bone,f and that each ossescent or temporary
cartilage, is an organic tissue, homogeneous, more or less pel-
lucid, elastic, in its first state almost colorless, afterwards assum-
ing a bluish cast, and having a great many peculiar minute
corpuscles interspersed through its substance, as shown by the
microscope. In the conversion of cartilage into bone, the
'change first commences in the cartilage that surrounds the
corpuscles.

— Weber, Beclard and others, believe that the calcareous matter
is deposited by the vessels, in the cartilaginous mould of the
•tyone, as a foreign body, and that the cartilaginous particles are
removed in proportion to make room for it ; but this is a mere
opinion which has not been proven.

— Miescher, asserts that he was unable even with the micro-
scope to ascertain in what manner, the calcareous particles were

* More recent researches seem to prove that the average diameter of these
cartilage cells or corpuscles, is about the one twelve hundredth or one fifteen
hundredth part of an inch. — P.

f This which was admitted by Albinus, Haller/ Scarpa; and others, has been
denied by Howship and Beclard, in regard to the diaphysis of the long bones,
and the bones of the cranium. In the bones of the rabbit, Miescher found a
mould of cartilage before a particle of ossific matter had been deposited, and
between the pericranium and dura mater, a thin stratum of cartilage. An ex-
ception must be made however in regard to certain flat bones of the human
skull, as the parietal. — p.

46

NEW VIEWS OF THE GROWTH OF BONES.

received into the cartilage, the strongest powers of the micro-
Fig. 8.* scope exhibiting no cells in which they

were placed, nor any calcareous particles
of the size of the dispersed corpuscles ;
all that appeared positively was that the
cartilage seemed by degrees to assume the
aspect of bone.

The more recent researches of Gerber,f
have given* if not a perfectly clear, at
least a more satisfactory explanation of
the manner in which the ossific cartilage
is so modified, as to form bone. The
primitive physical formation of all car-
tilage is cellular, that is they grow from
cell-germs, as is the case with the other
tissues of the body. These cell-germs or
cartilage corpuscles are seen at A. Fig. 8,
magnified 250 diameters. Between these
cells and filling up the vacant spaces
between them, is an amorphous, hyaline
or transparent intercellular substance ;
the cells themselves are filled with . a
softish granular matter. As the cartilage*
increases in growth, new cells are develop-
ed in the hyaline substance by which the
older ones are pushed farther and farther
from each other. The original cells pro- *
duce two or more young or secondary
cells by the development of their gra-
nular nuclei : between these secondary
cells is also formed a secondary hya-
line substance, and thus the orginal cells form each one a little
group of cells enclosed within itself, and to each group the name

* Fig. 8. A scheme intended to represent cartilage in the progressive stages of
ossification, magnified 250 diameters. A. Cartilage with the regularly dissemi-
nated corpuscles of Purkinje — cellular cartilage B. The corpuscles when ossi-
fication has begun, are forced into groups, between which the hyaline cartilage
is transformed into bone cartilage. This bone cartilage has now undergone a
change, so as to be chemically different from those cartilages which are to remain

f Elements of General and Minute Anatomy by T. Gerber. London, 1842.

NEW VIEWS OF THE GROWTH OF BONES. 47

of cartilage corpuscle is still applied. This is the common em-
bryonic constitution of cartilage. The fixed character of the
cartilage depends upon the after changes which take place in
it. If fibre-cartilage be formed, the intercellular or hyatme sub-
stance is developed in the form of fibres and the cells disappear
altogether. If elastic cartilage, fibres are developed around the
cells forming a kind of network. If ossific cartilage, the hya-
line substance takes on a stratified arrangement round the car-
tilage cells, and in it a new set of corpuscles are developed,
called the bone corpuscles, that are the nuclei of the bone
cells, see Fig. 9, of which the microscope has shown in reality
all bony structure to consist. As this process is commencing,
the cluster of cartilage cells called cartilage corpuscles, become
compressed together. The secondary hyaline substance becomes
dissolved, transudes through the walls of the parent cell,
coagulates round it, and in this state of cytoblastema as it is
called — this basis structure for the growth of other parts — it con-
stitutes the proper ossific cartilage. In it arise the bone cor-
puscles, called cytoblastty or germs, from which are formed the
bone cells. These follow the same mode of development, as
the embryonic cartilage cells : that is new corpuscles are
forming in the cytoblastema, while those recently produced
are growing ; the cartilage corpuscles ever more closely com-
pressed together disappear ; radiated points, nutrient vessels, etc.
make their appearance, the nuclei of the bone cells, (corpuscles,)
and the cells themselves when completely formed receive depos-
its of calcareous salts, and the formation of bone is achieved.

flexible during life. It does not on boiling yield gelatine like them, but a sub-
stance called chondrin, which differs from gelatine in not being precipitated by
tannic acid, etc. C. The groups of cartilage corpuscles are now seen completely
inclosed by bone cartilage. D. The cartilage corpuscles are here rendered less
transparent by the process of resolution that is going on ; the bone corpuscles
are at the same time making their appearance in the bone cartilage. E. The
cartilage corpuscles are dissolved and partially removed. F. The cartilage cor-
puscles have disappeared ; have been absorbed. G. In spongy bones, the spaces
occupied by the cartilage corpuscles remain as cells filled with globules of fat.
In compact bones the cells are reduced to minute canals, by the growth of bony
matter, or they disappear entirely. In Fig. 9, there is a representation of bone
in its perfectly formed state, magnified 450 diameters, and representing the bone
cells or corpuscles, with iheir calcareous canals.

48 FORMATION OF CALLUS.

Fig. 9.* It is according to this from a peculiar sub-
stance, not ordinary cartilage, that bone is pro-
duced, and we now know that the effused fluid
of which the callus in fractures is formed, is in
some respects different from the cartilagi-
nous mould of bone, and that in fact bone
is developed in many parts of the body, as
in the human .skull for instance, without the.
existence of any previous cartilaginous basis.

Formation of Callus.

— The most ancient opinion entertained in regard to the mode of
union between broken bones, was, that it was owing to the con-
cretion of a viscous fluid, or imaginary osseous juice poured out
between the fragments. This was the opinion of Haller. Du-
hamil demonstrated the fallacy of this belief, by numerous
experiments, and instituted a theory of his own which is much
nearer the truth. According to him the production of callus or
new bony matter, is owing to the swelling, elongation, and
subsequent adhesion between the periosteum and medullary
membrane of one fragment with the corresponding parts of the
other; and that from these membranes thus modified, bony
matter was deposited in the form of a ring on the exterior of
the bone and a plug in its medullary cavity, which held the
fragments together by passing across the cavity of fracture, and
sometimes by prolongations passing between them through the
cavity. John Hunter believed that the re-union of fractured
bones took place from the organization of the blood effused
around the fracture and between the fragments ; a doctrine
which now has few supporters.
— The credit of giving the most faithful account of the forma-

* Fig. 9. Bone corpuscles, a, magnified 450 diameters, which have here been
converted into bone cells, b. Branches of the bony cells which by their inoscu-
lations form a net work. They are called by Mttller the canaliculi calicophori.
It is not yet fully decided whether or not the cells and their branches are filled
with calcareous matter, or merely incrusted with it. The diameter of these
calcigerous canals (canalic. calicoph.) is reckoned at their largest parts to be
between one fourteen thousandth and the one twenty thousandth part of an inch.

RESTORATION OF FRACTURED BONES. 49

tion of callus, is due to Dupuytren* and Sanson. According
to these, the union of fragments of bone, is effected by the for-
mation of two successive stages of callus. One which is pro-
visional or temporary, is completed usually in the sp^ce of
thirty or forty days, by the union and ossification of the perios-
teum, cellular tissue, and even in some cases of the muscles,
so as to constitute an external ring — and of the medullary mem-
brane, so as to constitute an internal plug. The other, which
he calls final or permanent, is formed by the re-union of
the surfaces of the fracture, with a solidity so much superior ./ /C
to that of the bone in other parts, that it will break any where
again, rather than at that point, and which is never fully com-
pleted, notwithstanding the limb appears earlier than this restored
to its proper uses, under eight, ten, or twelve months, by which
time all the provisional callus has been removed, and the medul-
lary canal is completely re-established.

— Dupuytren divides the successive organic changes, which
attend the formation of callus, into five periods.
— The first period, extends from the time of the fracture to X
the eighth or tenth day, and is characterized by the following
phenomena : the medullary membrane, the medulla, the perios-
teum, cellular tissue, and sometimes the muscles themselves, are
torn at the time the fracture takes place ; blood escapes from
the ruptured vessels, surrounds the fragments, spreads in the
medullary canal and infiltrates in the surrounding tissue : the
hemorrhage stops ; a slight inflammation is developed in all
these parts, which is the first step towards the production of
the callus. The cellular tissue surrounding the bone, becomes
very vascular, is thickened, loses its elasticity, and acquires a
great degree of consistence ; it sends irregular processes into
the neighboring muscles, transforms them to a greater or less
extent into an analogous tissue, and unites them in a common
structure with the periosteum, which is also much thickened
and very vascular. A nearly similar change takes place in the
cavity of the bone in respect to the medulla and its membrane.
The calibre of the medullary canal is contracted by the thickening

- * Journal Univ. de Med. torn. 20.
5

50 RESTORATION OF FRACTURED BONES.

of the membrane, which presents a fleshy appearance, in con-
sequence of a sort of gelatinous infiltration. The effused blood
becomes absorbed, and a ropy, viscous, gelatinous fluid, is
poured out between the ends of the fragments, which is essential
to the production of the permanent callus.

— The second period extends from the tenth or twelfth, to the
twentieth or twenty-fifth day. During this period, the engorge-
ment of the surrounding parts, diminishes and the muscles are
liberated : but the cellular tissue remains condensed and con-
centrated round the fracture, presenting grooves or even canals
to the tendons of the muscles if any pass in the vicinity of the
fracture, in which they are able to play, though with little free-
dom, in consequence of some existing induration of the cellular
tissue. This constitutes the provisional callus, the external
portion of which is thickest at the place of fracture, and insensibly
terminates upon the fragments of bone. Its internal portion is
formed by the periosteum, which is closely attached to the bone.
Its structure is whitish, homogeneous, and of a cartilaginous or
fibro-cartilaginous character. The medullary membrane forms a
similar plug of provisional cartilaginous matter, which fills up the
whole cavity of the bone, above and below the place of fracture.
The viscous or gelatinous fluid interposed between the ends of
the bones, is now rose-colored or red, presents sometimes a floc-
culent appearance, and is adherent by its margins to the external
and internal callus. The limb may still be bent at the place of
fracture, but no crepitation can be produced.
— The third period extends from the twentieth or twenty-fifth
day, to the thirtieth, fortieth or sixtieth, according to the age
and health of the patient.

— Ossification commences in the centre of the cartilage, and by
degrees the whole tumor, internal and external, becomes os-
seous. It is very vascular, and Howship* has succeeded in
injecting the vessels. If at this period the bone be cut longitu-
dinally, the provisional callus will be found presenting all the
characters of spongy bone, while the fragments will be found

* Microscop. Observ.

TERMS USED IN THE DESCRIPTION OF BONES AND JOINTS. 51

movable upon each other, the substance poured out between
them, not having apparently undergone much change.
— The fourth period extends from the fiftieth or sixtieth day,
to the fifth or sixth month. During this period the ^callus
has been changed from the state of spongy, to that of compact
bone.

— The substance intermediate to the fragments, which present-
ed itself under the form of a line or septum between them,
becomes more consistent, presents a whiter hue, and is ossified
towards the end of this period ; and the permanent callus is
now completed.

— The fifth period extends from the fifth or sixth, to the
eighth, tenth or twelfth month, during which time the whole
of the provisional callus is entirely removed, the object of its
formation having been effected, that of, securely holding the
bones together like splints till the fractured surfaces become
firmly reunited. The periosteum resumes its usual thickness
and polish, and the muscles and tendons their entire freedom of
motion.

— The internal plug of callus having been removed by absorp-
tion, the central cavity of the bone, the medullary membrane
and the marrow itself, present their usual appearance. —

i

Of the Terms used in the Description of Bones and their
Articulations.

The study of this subject has been rendered more difficult
by the unnecessary introduction of many hard words, but some
of these words are so generally used, that they ought to be
understood by the student of anatomy.

The word process signifies any protuberance or eminence
arising from a bone.

Particular processes receive names from their supposed resem-
blance to certain objects ; and their names are very often com-
posed of two Greek words ; thus the term coracoid, which is
applied to a well-known process, is derived from the Greek
words xo£«!,, a crow, and eidos*, resemblance.

52 TERMS USED IN THE DESCRIPTION OF BONES AND JOINTS.

If a process has a spherical form, it is called a head. If the
head is flattened on the sides, it is denominated a condyle.

A rough protuberance is called a tuberosity. ,A ridge on the
surface of a bone is called a spine.

The term apophysis, is nearly synonymous with process. It
signifies a protuberance that has grown out of the bone, and is
used in opposition to the term epiphysis, which signifies a por-
tion of bone growing upon anther, but distinct and separable
from it ; as is the case in infancy with the extremities of the
long bones.

The cavities on the surfaces of bones are named in the same
way, as will appear by a reference to the glossary at the end of
this work.

Words of this kind have been used most profusely in the
descriptions of articulations, and here also their utility is doubt-
ful. Therefore, for many terms used on this occasion, the reader
is referred to the glossary ; but the following are necessary to
be understood.

SYMPHYSIS does not merely imply the concretion of bones
originally separate, as its derivation imports ; but it is under-
stood also to mean the connexion of bones by intermediate
substances. Thus, there are three species of symphysis,
particularly noticed, viz.

Synchondrosis, when bones are connected to each other by
cartilage ; as the ribs and sternum.

Synneurosis, when they are connected by ligaments, as in the
movable articulations.

Syssarcosis, when they are connected by muscle. The different
articulations are of two kinds, viz. Synarthrosis and Diar-
throsis.

SYNARTHROSIS is the name of that kind of articulation which
does not admit of motion. There are three species of synar-
throsis, viz.

Suture, when the indented edges of the two bones are received
into each other, as is the case with the bones of the cra-
nium.

TERMS USED IN THE DESCRIPTION OF BONES AND JOINTS. 53

Gomphosis, when one bone is fixed in another like a nail in a

board, as the teeth in their sockets.
Shindyksis, when the thin edge of one bone is received into a

narrow furrow of another, as the nasal plate of the efnmoid

in the vomer.
DIARTHROSIS is the name of that kind of articulation which

admits of motion. Of these articulations there are three

species, viz.
Enarthrosis, when a large head is received in a deep cavity, as

the head of the thigh bone in the acetabulum.
A.rthrodia, when the head is connected with a superficial

cavity.
GingKmus, when the extremities of bones apply to each other

so as to form a hinge.

But most of the important joints have so many peculiarities
that they cannot be understood without studying them sepa-
rately. It may, therefore, be doubted whether the classification
and arrangement of joints is any way necessary.
— Some of the more common anatomical terms are explained
in this place and in the glossary ; but they have now become
too numerous, in consequence of the introduction of a multitude
of new ones, some of which are of foreign origin, to be sepa-
rately defined in this work. A medrcal dictionary will better
serve the purposes of the student. That of Prof. Dunglison,*
will be found the most comprehensive and useful.

* Medical Lexicon — A new Diet, of Med. Science. 3d edit, by Robley Dun-
glison, M. D.? Prof. Inst. Med., tec., in Jeff. Med. Coll. Lea & Blanchard.
Phil. 1842.

5*

54 OF THE HEAD.

CHAPTER II.

Of the skeleton and its different parts, and the individual bones of which they

are composed.
•

THE bones of an animal arranged and connected to each other
in their natural order, separate from the soft parts, compose a
skeleton.

The skeleton is said to be natural when the bones are
connected by their own ligaments, which have been allowed to
remain for that purpose.

It is called artificial when the bones are connected with wire,
or any foreign substance.

The artificial skeleton is best calculated for studying the
motions of the different bones, because the dry and hard
ligaments of the natural skeleton do not allow the bones to
move ; but the bones of young animals do not admit of the
preparation necessary for an artificial skeleton, as their epiphyses
would separate, and they are therefore formed into natural
skeletons.

The study of the skeleton and its mechanical properties, as a
piece of machinery, is absolutely necessary to a perfect under-
standing of many motions of the body, and of the action and
co-operation of muscles ; but any observations on this subject
will be better understood after the individual bones and the
muscles have been described.

The skeleton is divided into the head, the trunk, the superior
and the inferior extremities.

Of the Head.

The Head comprehends the CRANIUM, and FACE.

The cranium consists .of eight distinct bones, which, when
placed in their natural order, form a large spheroidal cavity for
containing the brain, with many foramina or apertures that
communicate with it.

OF THE CRANIUM. 55

These bones are of a flattened form. They are composed of
two lamina or plates called tables, with a cellular structure
between them, called meditullium, or diploe. The external
table is more firm and thick than the internal. The letter is
comparatively very brittle, whence it is called the vitreous
table. [Between the two tables which compose the flat bones
of the cranium and running through the diploe are several
sinuses, which are occupied by veins in the recent subject.
They were discovered by M. Fleury about forty years ago,
while he was Prosector at the School of Medicine in Paris, and
engaged in some inquiries relative to the structure of the
cranium at the instigation of M. Chaussier. The account
which M. Chaussier gives of these veins is as follows : they are
situated in the middle of the diploe between the two tables of
the skull, and like all other veins are intended to return the
blood to the heart. They are furnished with small valves,
have extremely thin and delicate parietes, and commence by
capillary rami6cations coming from the different points of the
vascular membrane which lines the cells of the diploe. Their
roots are at first extremely fine and numerous, form by their
frequent anastomoses a kind of network, and produce by their
successive junction, ramuscles, branches, and large trunks,
which, becoming still more voluminous, are directed towards the
base of the cranium. Some varieties exist in regard to the
number, size, and disposition of these trunks, but generally one
or two of them are found in each side of the frontal bone, two
in the parietal bone, and one in each side of the qccipital
bone. Anastomoses exist between these several trunks, by
which the veins in the parietal bone are joined to those in the
frontal and in the occipital. Branches from the right side of
the head also anastomose with some from the left side. Besides
the branches already mentioned, one or two smaller than the
others are directed towards the top of the head and terminate in
the longitudinal sinus.

The descending veins of the diploe communicate in their
passages with the contiguous superficial veins, and empty into
them the blood which they receive from the several points of

56

OF THE CRANIUM.

the diploe. These communications are produced through
small foramina which penetrate from the surface of the bone
to the diploe. The trunks of such diploic veins as are continued
to the base of the cranium, open partly into sinuses of the dura
mater, and partly into the venous plexus at the base of the
pterygoid apophyses, and form there the venous communications
called the emissaries of Santorini. Moreover, there are
communications sent from the dtploic veins through the porosi-
ties of the internal table of the skull to the veins of the dura
mater. This fact is rendered very evident by tearing off the
skull cap, when the surface of the dura mater will be studded
with dots of blood, and the internal face of the bone also,
particularly in apoplectic subjects. It appears indeed that the
arteries of the cranium are principally distributed on its external
surface, and the veins on its internal surface and diploe.

In the infant the diploic veins are small, straight, and have
but few branches : in the adult they correspond with the
description just given ; and in old age they are still more con-
siderable, forming nodes and seeming varicose. In children,
when the bones are diseased, they partake of the latter
character. In order to see them fully, the external table of the
skull must be removed with the chisel and mallet, both from its
vaults and base.]*

The periosteum, which is on their external surface, is called
pericranium. Internally the dura mater, or membrane which
covers the brain, supplies the place of periosteum.

There are eight of these bones, which are thus denominated :
Os Frontis, Ossa Parietalia, Ossa Temporum, Os Occipitis,
Os Sphenoides, and Os Ethmoides. The two last are called
common bones, to denote that they are connected with the bones
of the face as well as with those of the cranium.

The os frontis forms the whole fore part of the vault of the

* The diploe, or meditullium, corresponds exactly in structure and situation
with the spongy, or cellular tissue of the other bones of the body, though it has
unnecessarily received a distinct name. Neither are the diploic sinuses peculiar
to the bones of the skull. They are found presenting exactly the same appear-
ance in the bodies of the vertebrae, and appear in fact to be but a development
of the canaliculated tissue of the oiher bones. See Fig. 5, page 30. — P.

THE SUTURES. 57

cranium : the two ossa parietalia form the upper and middle
part of it ; the ossa temporum compose the lower part of the
sides ; the os occipitis makes the whole hinder part and some
of the base; the os ethmoides is placed between the ambits of
the eyes, and the sphenoides extends across the base of the
cranium.
i

The Sutures, f-

The above bones are joined to each other by five sutures ; the
names of which are the Coronal, Lambdoidal,' Sagittal, and
two Squamous.

The coronal suture is extended over the head, from within
about an inch of the external angle of one eye, to the like dis-
tance from the other ; which being near the place where the
ancients wore their garlands, this suture has hence got its
name. Though the indentations of this suture are conspicuous
in its upper part, yet an inch or more of its end on each side
has none, but is squarnous and smooth.

The lambdoidal suture begins some way below, and further
back than the vertex or crown of the head, whence its two legs
are stretched obliquely downwards, and to each side, in form
of the Greek letter A? and are now generally said to extend
themselves to the base of the skull ; but formerly, anatomists
reckoned the proper lambdoidal suture to terminate at the
squamous sutures : and the portion continued from them on each
side, where the indentations are less conspicuous than in the
upper part of the suture, they called additamentum suturae
lambdoidis.

This suture is sometimes very irregular, being made up of a
great many small sutures, which surround a number of insulated
bones, that are generally more conspicuous on the external
surface of the skull than internally. These bones are commonly
called triquetra or wormiana ; their formation is owing to a
greater than ordinary number of points of ossification in the
skull, or to the ordinary bones of the cranium not extending
their ossification far enough or soon enough ; in which case,
the unossified interstice between such bones begins a separate

58 THE SUTURES.

ossification, in one or more points ; from which the ossification
is extended to form as many distinct bones as there were points
which are extended into the large ordinary bones, and into
each other.*

The sagittal suture is placed longitudinally, in the middle
of the upper part of the skull, and commonly terminates at
the middle of the coronal and of the lambdoidal sutures ;
between which it is said to be.placed, as an arrow is between
the string and the bow. This suture is sometimes continued
through the middle of the os fronds down to the root of the
nose. *

The squamous agglutinations, or false sutures, are one on
each side, a little above the ear, of a semicircular figure, formed
by the overlapping (like one scale upon another) of the upper
part of the temporal bones on the lower part of the parietal,
where, in both bones, there are a great many small risings, and
furrows which are indented into each other : though these
inequalities do not appear until the bones are separated. In
some skulls, indeed, the indentations here are as conspicuous
externally as in other sutures ; and what is commonly called
the posterior part of this squamous suture, always has the
evident serrated form ; and therefore is reckoned by some a
distinct suture, under the name of additamentum posterius
suturae squamosae.

The squamous suture is not confined to the conjunction of
the temporal and parietal bones, but is made use of to join all
the edges of the bones on which each temporal muscle is
placed ; for the two parts of the.sphenoidal suture, which are
continued from the anterior end of the common squamous
suture just now described, one of which runs perpendicularly
downwards, and the other horizontally forwards ; and also the
lower part of the coronal suture already taken notice of, may all
be justly said to pertain to the squamous suture.

* These ossa triquetra or wormiana are also frequently met with in the sagittal
suture, and occasionally in all the different sutures of the cranium. As many
as fifteen or twenty have been seen in a single head, though usually their num-
ber is much less. Where the cranium is of a globular form, few, and frequently
none, are met with. They never begin to ossify till six months or a year after
birth.— P.

THE SUTURES. 59

This structure appears to depend upon the pressure of the
temporal muscle externally, and the resistance of the brain
within, which makes the bones so thin, that their edges opposed
to each other are not sufficiently thick to stop the extetysion of
their fibres in length, and thus to cause the common serrated
appearances of sutures ; but the narrow edge of the one bone
slides over the other. The squamous form is also more con-
venient here ; because such thin edges of bones, when accurately
applied one to another, have scarce any rough surface to
obstruct or hurt the muscle in its contraction ; which is still
farther provided for, by the manner of laying these edges on
each other ; for, in viewing their outside, we see the temporal
bones covering the sphenoidal and parietal, and this last sup-
porting the sphenoidal, while both mount on the frontal ; from
which disposition it is evident, that while the temporal muscle
is contracting, which is the only time it presses strongly in its
motion on the bones, its fibres slide easily over the external
edges. Another advantage of this structure is, that the whole
part is made stronger by the bones thus supporting each other.

The indentation of the sutures are not so strongly marked
on the inside as on the outside of the cranium ; and sometimes
the bones seem to be joined by a straight line : in some
skulls, the internal surface is found entire, while the sutures
are manifest without. By this mechanism, there is no risk of
the sharp points of the bones growing inwards, since the
external serrae of each of the conjoined bones rest upon the
internal smooth-edged table of the other.

The advantages of the sutures are these: 1. The cranium is
more easily formed and extended into a spherical figure, than
if it had been one continued bone. 2. The bones which are at
some distance from each other at birth, may then yield, and
allow to the head a change of shape, accommodated to the
passage it is engaged in. Whence, in difficult parturition,
the bones of the cranium, instead of being only brought
into contact, are sometimes made to mount one upon the
other.

[The sutures which unite the bones of the cranium, are

60 THE SUTURES.

generally said to be made by the radii of ossification, from the
opposite bones meeting and passing each other, so as to form
a serrated edge. This explanation is however insufficient, for
the following reasons : we always find the sutures in the same
relative situation, and observing the same course in the cranium ;
if they, then, depended exclusively on so mechanical a process,
as the shooting of the rays of bone across each other when they
met, in ossification on one side^rf the head occurring sooner or
faster than on the other, we ought to find the sagittal suture to
one side of the middle line ; it should also, in many instances,
be found crooked. Moreover, in all cases where bones arise
from different points of ossification and meet, particularly in
the flat bones, the serrated edges ought to be formed ; this,
however, is not the case. The os occipitis, which is formed
originally from four points of ossification, and has therefore as
many bones composing it in early life, never joins these bones
together by the serrated edge ; the acromion process of the
scapula is never united to its spine by sutures ; the three bones
of the sternum never unite by suture, and the same observa-
tion holds good in many other instances. Bichat, who rejects
this mechanical doctrine, advances an opinion much better
founded. The dura mater and the pericranium, before ossifi-
cation commences, form one membrane, consisting of two
lamina ; it is generally known that the flat bones of the
cranium are secreted between these two lamina ; now the out-
line of each bone, long before it has reached its utmost limits,
is marked off by partitions passing between these two mem-
branes. The peculiar shape of the bony junction, or the suture
in adult life, will, therefore, depend upon the original shape
of the partitions: when the latter are serrated, the points of
ossification will fill up these serrae ; but when they are simply
oblique, the squamous suture will be formed. This also
accounts for cases where the mode of junction is intermediate
to the squamous and serrated suture ; for the formation of the
ossa triquetra, and why in some skulls they do not exist,
whereas in others their extent and number are very considera-
ble. The inference will also be drawn from this, that in all ossi-

OS FRONTIS.

61

fications from different nuclei, where these original mem-
braneous septa do not exist, a suture will not be formed ; but
the bones will join each other, as in a case of callus between
the broken extremities of bones. When these septa "become
weak or thin, either from original tendency, as in the case of
the sagittal suture, which in early life is continued to the root
of the nose frequently ; or from advanced age, as in the case
of nearly all sutures, the bones of the opposite sides amalga-
mate, and no appearance of suture is left. It is easy to make a
preparation illustrative of these facts, and one now exists in
the museum of the University of Pennsylvania, in which, by
removing the bone from between the membranes by means of
an acid, and afterwards rendering the membranes transparent
with oil of turpentine, the septa are seen sufficiently distinctly.]

Os Frontis.

The os fronds, as its name imports, forms the front part of
the cranium, and the upper portion of the orbits of the eyes.

Fig. 10.* The external surface of this

bone is smooth at its upper
convex part ; but several pro-
cesses and cavities are ob-
servable below ; for at the
angles of each orbit, the
bone projects to form four
processes, two internal, and
as many external ; which are
denominated angular. Be-
tween the internal and exter-
nal angular processes on each
side, an arched ridge is ex-

* The external surface of the os frontis. 1. Frontal protuberance or boss of
the right side. 2. The superciliary ridge. 3. Supra-orbital ridge. 4. External
angular process. 5. Internal angular process. 6. Supra-orbital notch for the
transmission of the supra-orbital nerve and artery ; it is occasionally converted
into a foramen. 7. The nasal or superciliary boss ; the swelling around this
point denotes the situation of the frontal sinuses. 8. The temporal ridge, com-
mencing from the external angular process (4). The depression in which fig.
8 is situated is a part of the temporal fossa. 9. The nasal spine.

6

62 OS FRONTIS.

tended, on which the eyebrows are placed. Very little above
the internal end of each of these superciliary ridges, a protuber-
ance may be remarked in most skulls, called the superciliary or
nasal boss, where there are large cavities within the bone, called
sinuses. Between the internal angular processes, and in front
of the vacuity for the ethmoid bone, the edge of the os frontis
is serrated for articulation with the ossa nasi, and the process
of the upper maxillary bone ; a«d from the centre of this sur-
face a small process arises, which is called the nasal spine.
From the under part of the superciliary ridges, the frontal bone
runs a great way backwards : these parts are called orbitar
processes, which, contrary to the rest of this bone, are concave
externally, for receiving the globes of the eyes, with their
muscles, fat, &c.

In each of the orbitar processes, at the upper and outer
portion of the orbit, a considerable sinuosity is observed, where
the glandula lachrymalis is lodged. Near each internal angular
process a small pit may be remarked, where the cartilaginous
pulley of the superior oblique muscle of the eye is fixed.
Between the two orbitar processes, there is a large vacuity
which the cribriform part of the os ethmoides occupies. The
frontal bone has frequently little caverns formed in it where it is
joined to the ethmoid bone.

The foramina, or holes, observable on the external surface of
the frontal bone, are'three in each side.

On each supra-orbital ridge, 3 fig. 10, at the distance of one-
third of its length from the nose, is a foramen, or a notch,
through which pass a branch of the ophthalmic artery and a
small nerve called the supra-orbital.

In the internal edge of each orbitar process are two other
foramina denominated anterior and posterior orbitar, or eth-
moidal foramina, which lead to the nose : sometimes they are
only notches or grooves which join with similar grooves in the
bones below, and form foramina. They transmit the anterior
and posterior ethmoidal arteries and veins, and the former trans-
mits likewise the internal nasal branch of the ophthalmic nerve.

The internal surface of the os frontis is concave, except at

OS FRONTIS. 63

the orbitar processes, which Fig. 11.*

are convex, and support the
anterior lobes of the brain.
This surface is not so smooth
as the external ; for the larger
branches of the arteries of
the dura mater make some
furrows in its sides and back
parts, and its lower and fore
parts are marked with the
convolutions of the anterior
lobes of the brain. In the
middle of the concave inter-
nal surface is a groove, which
is small at its commencement, and gradually increases in dia-
meter as it proceeds upwards. This is formed by the superior
longitudinal sinus ; at its commencement is a ridge to which the
beginning of the falciform process of the dura, mater is attached.
At the root of this ridge is a small foramen, sometimes formed
jointly by this bone and the ethmoid ; it is denominated fora-
men ccECum ; in it a small process of the falx is inserted, and
here the longitudinal sinus begins.

The frontal sinuses are formed by the separation of the two
tables of this bone at the part above the nose and the internal
extremities of the superciliary ridges. In the formation of these
cavities, the external table commonly recedes most from the
general direction of the bone.

* The internal surface of the frontal bone ; the bone is raised in such a man-
ner as to show the orbito-nasal portion, i. The grooved ridge for the lodgment
of the superior longitudinal sinus and attachment of the falx. 2. The foramen
caecum. 3. The superior or coronal border of the bone ; the figure is situated
near that part which is bevelled at the expense of the internal table. 4. The
inferior border of the bone. 5. The orbital plate of the left side. 6. The cellu-
lar border of the ethmoidal fissure. The foramen ceecum (2) is seen through
the ethmoidal fissure. 7. The anterior and posterior ethmoidal foramina ; the
anterior is seen leading into its canal. 8. The nasal spine. 9. The depression
within the external angular process (12) for the lachrymal gland. 10. The de-
pression for the pulley of the superior oblique muscle of the eye ; immediately
to the left of this number is the supra-orbital notch, and to its right the internal
angular process. 11. The opening leading into the frontal sinuses. 12. The
same parts are seen upon the opposite side of the figure.

64 OSSA PARIETALIA.

These cavities are divided by a perpendicular bony partition,
which is sometimes perforated and admits a communication
between them. Their capacities are often very different in
different persons, and on the different sides of the same person.
In some persons whose foreheads were very flat, they are said
to have been wanting. They communicate with the nose by
means of a canal in the cellular part of the os ethmoides.

The os frontis is composed *)f two tables, and an interme-
diate diploe, as the other bones of the cranium are : it is of a
mean thickness between the os occipitis and the parietal bones ;
and is nearly equally dense throughout, except the orbitar pro-
cesses, where, by the action of the eye on one side, and pressure
of the lobes of the brain on the other, it is made extremely thin
and diaphanous, and the diploe is entirely obliterated. In this
place there is so weak a defence for the brain, that fencers
esteem a push in the eye mortal.

In such skulls as have the frontal bone divided by the sagittal
suture, the partition separating these cavities is evidently com-
posed of two plates, which easily separate.

Each of the frontal sinuses opens into one of the uppermost
cells in the' anterior part of the ethmoid bone, and this cell
communicates with the middle channel of the nose under the
anterior end of the os turbinatum superius.

This bone is united with the parietal, ethmoidal and sphe-
noidal bones of the head ; and with the nasal, maxillary, ungui-
form and malar bones of the face.

Ossa Parietalia.

Each of the two ossa parietalia is an irregular square ; its
upper and front edges being longer than the one behind or
below. The inferior edge is concave, the middle part receiving
the upper round part of the temporal bone. The angle formed
by the under and anterior edges is so extended as to have the
appearance of a process.

The external surface of each os parietale is convex. Upon
it, somewhat below the middle height of the bone, there is a

OSSA PARIETALIA.

65

transverse arched ridge, ge- Fig. 12.*

nerally of a whiter color
than any other part of the
bone ; from which, in bones
that have strong prints of
muscles, we see a great many
converging furrows, like so
many radii drawn from a
circumference towards a cen-
tre. From this ridge of each
bone the temporal muscle
rises : and, by the pressure of its fibres, occasions the furrows
just now mentioned. Below these we observe, near the semi-
circular edges, a great many risings and depressions, which are
joined to like inequalities on the inside of the temporal bone,
and form the squamous suture. Near the upper edges of these
bones, towards the hind part, is a small hole in each, through
which a vein passes from the teguments of the head to the lon-
gitudinal sinus.f o

On the inner concave surface of the parietal bones we see a
great many deep furrows, disposed somewhat like the branches
of trees : the furrows are largest and deepest at the lower edge
of each os parietale, especially near its anterior angle, where a
complete canal is sometimes formed.

[These furrows are made by the ramifications of the great
middle artery of the dura mater: they have been commonly
attributed to the pulsation of the artery causing the absorp-
tion of the bone, but it is more probable that the deposition of
the bone has been prevented where the artery beats, and thus
the bone becomes modelled over the artery in the same way
that it is made to conform to the surface of the brain. If it

* The external surface of the left parietal bone. 1 . Superior or sagittal border.
2. Inferior or squamous border. 3. Anterior or coronal border. 4. Posterior or
lambdoidal border. 5. The temporal ridge. The figure is situated immediately
over the parietal protuberance. 6. The parietal foramen, unusually large.
7. The anterior inferior angle. 8. The posterior inferior angle.

f It transmits, also, an artery from the integuments to the dura inater, and
is called the parietal foramen. — p.

6*

66 OSSA TEMPORUM.

were exclusively an absorption and not a deposition, we should
scarcely find the artery occasionally surrounded perfectly by
bone.]

Fig. 13.* On the inside of the up-

per edge of the ossa parie-
talia there is a large sinuos-
ity, frequently larger in the
bone of one side than of the
other, where the upper part
of the falx is fastened, and the
superior longitudinal sinus
is lodged. Part of the late-
ral sinuses generally makes
a depression near the angle
formed by the lower and
posterior edges of these bones ; and the pits made by the
convolutions of the brain are in no part of the skull more
frequent or more conspicuous, than in the internal surface of
these bones.

The ossa parietalia are the most equal and smooth, and are
among the thinnest bones of the cranium ; but they enjoy the
general structure of two tables and diploe most perfectly.

These bones are joined at their fore side to the os frontis, at
their long inferior angles, to the sphenoid bone ; at their lower
edge, to the ossa temporum ; behind to the os occipitis, or ossa
triquetra ; and above, to one another.

Ossa Temporum.^
The ossa temporum are situated at the lateral and inferior

* The internal surface of the left parietal bone. 1. The superior, or sagittal
border. 2. The inferior, or squamous border. 3. The anterior, or coronal border.
4. The posterior, or larabdoidal border. 5. Part of the groove for the superior
longitudinal sinus. 6. The internal termination of the parietal foramen. 7. The
anterior inferior angle of the bone, on which is seen the groove for the trunk of
the arteria meningea media. 8. The posterior inferior angle, upon which is seen
a portion of the groove for the lateral sinus.

f This bone has received the name of temporal, because at the region which
it covers, the hair usually commences to turn gray, and thus in some measure
indicates the different periods of life. — p.

OSSA TEMPORUM. 67

parts of the cranium ; each of them is divided into three portions,
a superior or squamous, a posterior or rnastoid, and a middle or
petrous.

The squamous portion is nearly semicircular in font!, and
very thin ; its edge is sharp, and the inner table appears pared
away to form the squamous suture • with the corresponding
edge of the parietal bone. Its external surface is covered by
the temporal muscle. At the lower and anterior part of this
surface, the zygomatic process arises, it proceeds forward to
join the cheek bone, and form an arch under which the tem-
poral muscle passes.

At the base of the process is the glenoid cavity for the condyle
of the lower jaw. Immediately before this cavity is a tubercle
or protuberance, near the commencement of the zygoma and
at its lower border, to which the external lateral ligament of
the lower jaw is attached ; continued horizontally inwards
from the tubercle there is a rounded eminence, called the emi-
nentia articularis, which forms part of the articular surface on
which the condyle rises when the jaw is opened. In the pos-
terior part of the cavity is a fissure — called the glenoid — in
which part of the ligament of this articulation is fixed. In
this fissure is an aperture — glenoid foramen — which communi-
cates with the cavity of the tympanum of the ear, and is occu-
pied by a small nerve called chorda tympani ; and also by the
anterior muscle of the malleus — one of the small bones of the
ear.

The internal surface of the squamous portion is concave ; it
is marked by pits and small eminences, which correspond with
the convoluted surface of the brain, and also by impressions of
the arteries of the dura mater, see 4 fig. 13, as they go towards
the parietal bone.

The mastoid or occipital portion is the smallest of the three
parts of the bone ; it consists of an angular portion, which
occupies a vacuity between the occipital and parietal bones ;
and of the mastoid process. The mastoid process has some
resemblance to the nipple; it is composed internally of cells
which communicate with the cavity of the tympanum. On

68 OSSA TEMPORUM.

the internal side of its base is a deep groove in which the pos-
terior belly of the digastric muscle is inserted. Behind this
process is the mastoid hole, which transmits a vein, and some-
times a small artery.

On the internal surface of this portion is a large groove,
which is formed by the lateral sinus. The mastoid hole above
mentioned, opens into this groove.

The petrous portion, which is * Fig. 14.*

situated between the squa-
mous and mastoid, resembles
a triangular pyramid lying on
one of its sides. When in its
proper position it projects
inward and forward. The
two upper sides form a por-
tion of the internal surface of
the base of the cranium. The
angle formed by these sur-
faces is very prominent, and divides the fossa for the middle
lobes of the brain, or rather the cavities for the cerebrum from
those which contain the cerebellum.

One of these sides of the petrous portion looks forward and

outward, the other backward and inward. Each of them has

eminences and depressions to correspond with the convolutions

i of the brain. Near the middle of the anterior side is a small

j furrow, leading to a foramen denominated Innominatum or

i Hiatus Fallopii which transmits the vidian nerve to the aque-

i duct of Fallopius.

* The external surface of the temporal bone of the left side. 1. The squamous
portion. 2. The mastoid portion. 3. The extremity of the petrous portion.
4. The zygoma. 5. Indicates the tubercle of the zygoma, and at the same time
its anterior root turning inwards to form the eminenlia articularis. 6. The
superior root of the zygoma, forming the posterior part of the temporal ridge.

7. The middle root of the zygoma terminating abruptly at the glenoid fissure.

8. The mastoid foramen. 9. The meatus auditorius externus, surrounded by
the processus auditorius. 10. The digastric fossa, situated immediately to the
inner side of (2) the mastoid process. 11. The styloid process. 12. The vagi-
nal process. 13. The glenoid or Glaserian fissure ; the leading line from this
number crosses the rough posterior portion of the glenoid fossa. 14. The open-
ing and part of the groove for the Eustachian tube.

OSSA TEMPOREM. 69

— There is another small oblique foramen immediately beneath
this, which transmits the nervous petrosus superjicialis minor, a
branch of Jacobson's nerve ; near the apex of the petrous por-
tion of the temporal bone there is seen a large forampn, the
termination of the carotid canal. On this anterior face of the
bone, especially in the young subject, is seen a rising or eminence
running from base to apex, which is formed by the projection
of the perpendicular semicircular canal.

About the middle of the posterior side is the large aperture
called meatus auditorius internus. The bottom of this cavity
is perforated by several foramina : the largest and uppermost
of which is the orifice of a winding canal, called improperly
the aqueduct of Fallopius, which transmits the portio dura of
the seventh pair of nerves. The other foramina transmit the
fibres of the portio mollis of the same nerve. Posterior to the
orifice of the meatus internus is an oblong depression, with a
foramen in it, covered by a shell of bone, which is the orifice
of a proper aqueduct or canal that passes from the vestibule of
the ear.*

— Neither of the so called aqueducts of the vestibule or cochlea,
are deserving of the name which has nevertheless been con-
tinued to designate them, since we no longer believe with
Cotugnius their discoverer, that they are a sort of passages, to
admit of the overflow of the lymph, when it was secreted in
superabundance in the labyrynth. They are both mere open-
ings, for the transmission mainly of blood vessels. The aque-
duct of the vestibule transmits a small artery and vein to the
vestibule, and lodges a process of the dura mater. —

The inferior side of the petrous portioh forms a part of the
external surface of the basis of the cranium. On the back part
of it is the external orifice of the canal, ^hrough which the
portio dura passes. It is called foramen stylo mastoideum.
Before this foramen is a long and slender styloid process,
which varies from one to two inches in length ; it projects

* This orifice should not be confounded with one which is nearer to the meatus
interims, and situated on the angle made by the two sides of the bone. — H.

70 OSSA TEMPORUM.

almost perpendicularly from the Fig. 15.*

basis of the cranium, and

gives origin to a muscle of the

tongue, of the os hyoides, and

of the pharynx, and also to

several ligaments. The base

of this process is surrounded

by a flat projection of bone,

occasionally called the vaginal

process.

On the inside of this pro-
cess, and rather before it, is
the jugular fossa, which, when applied to a corresponding part
of the occipital bone, makes the posterior foramen lacerum,
through which the internal jugular vein, and the eighth pair
of nerves pass out. A small spine called the jugular process
often projects into this foramen from the temporal bone, and
separates the nerve from the vein ; the nerve being anterior.
— Upon a ridge which is found at the root of this spine, and
just behind the margin of the carotid foramen, there is a small
opening leading into the canal which transmits Jacobson's
tympanic branch of the glosso-pharyngeal nerve, which forms

* The left temporal bone, seen from within. 1. The squamous portion.
2. The mastoid portion. The number is placed immediately above the inner
opening of the mastoid foramen. 3. The petrous portion. 4. The groove for
the posterior branch of the arteria meningea media. 5. The bevelled edge of
the squamous border of the bone. 6. The zygoma. 7. The digastric fossa
immediately internal to the mastoid process. 8. The occipital groove. 9. The
groove for the lateral sinus. 10. The elevation upon the anterior surface of the
petrous bone marking the situation of the perpendicular semicircular canal.
11. The opening or termination of the carotid canal. 12. The meatus auditorius
internus. 13. A dotted line leads upwards from this number to the narrow
fissure which lodges a process of the dura mater. Another line leads down-
wards to the sharp edge which conceals the opening of the aquseductus cochleae,
while the number itself is situated on the bony lamina which overlies the open-
ing of the aquaeductus vestibuli. 14. The styloid process. 15. The stylo-mas-
toid foramen. 16. The carotid foramen. 17. The jugular process. The deep
excavation to the left of this process forms part of the jugular fossa, and that to
the right is the groove for the vein of the cochlea. 18. The notch for the fifth
nerve upon the upper border of the petrous bone, near to its apex. 19. The
extremity of the petrous bone which gives origin to the levator palati and tensor
tympani muscles.

OSSA TEMPORUM. 71

an important part of the nervous plexus of the tympanum. —
Before this spine, or partition, is the orifice of the second aque-
duct of the ear, the aqueduct of the cochlea, through which
passes a vein from the cochlea to the internal jugular, -6nd in
which is lodged a process of the dura mater. This jugular
fossa is at the termination of the groove, in the internal surface
of the bone, made by the lateral sinus. At a small distance
before the jugular fossa is the commencement of the carotid
canal, which makes a curve almost semicircular, and then pro-
ceeds in a horizontal course to the anterior extremity of the
bone : through this winding canal passes the carotid artery, and
the filaments from the fifth and sixth pair of nerves, which are
the beginning of the intercostal or sympathetic nerve.

Between the carotid canal and the cavity for the condyle of
the lower jaw, at the junction of the anterior part of the
squamous portion with the petrous portion of this bone, is a
very rough aperture, the bony margin of which appears broken ;
this is the orifice of the bony part of the Eustachian tube, or
passage from the throat to the ear. This canal is divided
lengthwise by a thin bony plate ; the upper passage contains
the internal muscle of the malleus bone of the ear (tensor
tympani) ; the lower and largest canal is the bony part of the
Eustachian tube.

The external passage to the ear, called Meatus Auditorius
Externus, is situated between the zygomatic and the mastoid
processes. The orifice is large and smooth above, but rough
below, and is surrounded by a rough lip called the auditory
process. The direction of the canal is obliquely inward and
forward.

— Angles of the bone. The superior angle of the bone which
separates the anterior and posterior faces, is sharp and gives
attachment to the tentorium cerebelli. It is slightly grooved
for the lodgment of the superior petrous sinus, and near its
extremity is marked by a smooth notch, upon which rests the
fifth or trigeminus nerve. The anterior angle which separates
the anterior from the inferior or basilar surface of the bone, is
grooved for the Eustachian tube, and forms the posterior

OS OCCIPITIS.

boundary of the foramen lacerum anterius of the base of the
cranium. The posterior angle separating the posterior from the
basilar surface of the bone, is grooved for the inferior petrous
sinus and excavated for the jugular fossa : it forms the anterior
boundary of the foramen lacerum posterius. —

The temporal is articulated with the parietal, occipital and
sphenoidal bones, and by its zygomatic process with the malar
bone.

Os Occipitis.

The occipital bone is situated at the posterior and inferior part

of the cranium ; it is of a rhomboidal figure, with convex and

concave surfaces.

Fig. 16.* The upper part of the

external surface is smooth : at
a small distance above the
middle of the bone is the
external occipital protube-
rance, with a curved line on
each side of it. Near the
middle of the bone the tra-
pezii muscles are attached to
this line, and externally, on
each side, the occipito fron-
talis, and the sterno mas-
toideus. Under this line is a
depression, on each side, into

which are inserted the complexus and the splenius capitis

muscles.

Below this is the inferior curved line, and still lower is a

* The external surface of the occipital bone. 1. The superior curved line.
2. The external occipital protuberance. 3. The spine or vertical ridge. 4. The
inferior curved line. 5. The foramen magnum. 6. The condyls of the right
side. 7. The posterior condyloid fossa, in which the posterior condyloid foramen
is found. 8. The anterior condyloid foramen, concealed by the margin of the
condyle. 9. The jugular eminence or transverse process as it is sometimes
called. 10. The notch in front of the jugular eminence, which forms part of
the jugular foramen. 11. The basilar process. 12. The rough projections into
which the moderator ligaments are inserted.

os OCCIPITIS. 73

muscular depression to which the rectus minor posticus is
attached on each side near the middle ; and the rectus major
posticus, and obliquus superior, near the end.

Below the protuberance is a spine which passes do\yn the
middle of the bone, and at the lower extremity of this spine is
the great occipital foramen, which forms the communication
between the cavities of the cranium, and the vertebral column.
This great opening transmits the medulla spinalis with its
membranes, the accessary nerves of Willis, and the vertebral
arteries and veins.

It is rather of an oval form, and the occipital condyles are
situated anteriorly on its edges. These condyles are of an
irregular oval figure ; they are not parallel, but incline towards
each other anteriorly. Their articulating surfaces are oblique,
looking downward and outward ; they are received into
corresponding cavities of the atlas, or first cervical vertebra,
and form with them the articulation of the head and neck.
From the oblique position of their articulating surfaces, as well
as the length of their ligaments and the inclination of their
axes towards each other, it results, that their motion is confined
to flexion and extension. On the internal sides of these
condyles is a rough surface, to which are attached the strong
ligaments that come from the processus dentatus of the second
vertebra of the neck.

Behind each condyle is a depression in which is situated the
posterior condyloid foramen, for transmitting the cervical
veins ; and at their anterior extremities are two large foramina,
(anterior condyloid,) through which pass the ninth pair of
nerves.

On the internal surface of the os occijfitis is the crucial
ridge, to which are attached the falx cerebelli or vertical,
and the tentorium or horizontal process of the dura mater.

The groove made by the longitudinal sinus continues from
the sagittal suture along the upper limb of this cross. Some-
times it is on the side of the ridge, and sometimes the ridge is
depressed, and it occupies its place ; at the centre of the cross,
where is lodged the torcular Herophili, formed by the
7

74

OS OCCIPITIS.

common junction of the sinuses, the groove for the longitu-
dinal sinus divides into two grooves for the lateral sinuses ;
Fig. 17.* these form the horizontal

limbs of the cross, and pro-
ceed towards the foramen
lacerum where the lateral
sinuses emerge from the
cavity of the cranium. The
lower limb of the cross is
formed by a spine which pro-
ceeds from the centre of the
bone to the great occipital fora-
men, and supports the falx of
the cerebellum. The internal
surface of the bone is divided
by the cross into four por-
tions, each of which is con-
siderably depressed so as to form fossae ; the two upper by the
posterior lobes of the cerebrum, and the lower by those of the
cerebellum.

This circumstance occasions great inequality in the thickness
of the bone, as the depressed portions are extremely thin, while
the ridge adds greatly to the thickness, especially at the centre
of the cross, which is opposite to the great external protuber-
ance.

Before the great occipital foramen is the cuneiform process,
which is thick and substantial ; it terminates by a broad
truncated extremity, that is articulated with the body of the
sphenoid bone. The internal surface of the cuneiform process

* The internal surface of the occipital bone. 1. The left cerebral fossa.
2. The left cerebellar fossa. 3. The groove for the posterior part of the superior
longitudinal sinus. 4. The spine for the falx cerebelli, and groove for the
occipital sinuses. 5. The groove for the left lateral sinus. 6. The internal
occipital protuberance which lodges the torcular Herophili. 7. The foramen
magnum. 8. The basilar process, grooved for the medulla oblongata. 9. The
termination of the groove for the lateral sinus, bounded externally by the jugu-
lar eminence. 10. The jugular fossa • this fossa is completed by the petrous
portion of the temporal bone. 11. The superior border. 12. The inferior border.

13. The border which articulates with the petrous portion of the temporal bone.

14. The anterior condyloid foramen.

OS ETHMOIDES. 75

is somewhat excavated, and forms a large superficial groove for
the medulla oblongata ; on each side of this groove is a small
furrow for the inferior petrous sinuses.

The two upper edges of the occipital bone are serrated, to
articulate, with those of the parietal, and form the lambdoidal
suture. The inferior edges are divided into two portions by a
small prominence called the jugular eminence ; the upper and
posterior portion is also serrated for articulation with the
mastoid portion of the temporal ; the inferior portion, which
is not serrated, applies to the petrous portion of the temporal
bone, and a notch in it contributes to the formation of the fora-
men lacerum.

The upper angle of this bone is acute, the lateral angles are
obtuse, and the inferior truncated. It is articulated with the
parietal, the temporal, and the sphenoidal bones.

Os Ethmoides.

The 05 ethmoides is truly one of the most curious bones of
the human body. It appears almost a cube, not of solid bone,
but exceedingly light and spongy, and consisting of many con-
voluted plates, which form a network like honey-comb. It is
firmly 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 ethmoid. " Other plates are so arranged that they form a
cellular structure, on which the olfactory nerves are expanded
by means of a particular membrane ; while an additional plate,
appropriated to the nose, descends into that cavity in a perpen-
dicular direction, and forms a large proportion of the partition
which divides it into two chambers.

The cribriform plate is situated in the anterior part of the
basis of the cranium. The cellular part occupies most of the
space between the orbits of the eyes, and the perpendicular plate
is to be found in the septum of the nose.

The ethmoid bone, for the purposes of description, may be ,
divided into three parts, viz. the cribriform plate, the nasal or (
perpendicular lamella, and the cellular portions. ,

76 OS ETHMOIDES.

The cribriform plate is oblong in shape, and firm in its
structure ; in the middle of the anterior extremity the crista
galli projects from its upper surface, dividing it into two lateral
portions, each of which is rather concave, and occupied by the
bulbous extremity of the olfactory nerve ; it is perforated by
many foramina, which transmit the fibres of the aforesaid
nerve. Near the crista galli, on each side, there is a small fis-
sure, through which passes a nCrvous filament derived from the
ophthalmic branch of the fifth pair. The crista galli varies in size
in different subjects : the beginning of the falciform process of
the dura mater is attached to it, and with the opposite part of
the os frontis it forms the foramen ca3cum, already mentioned.
It is very conspicuous in the basis of the cranium.

The nasal plate of the ethmoid bone seems to be continued
downwards from the crista galli through the cribriform plate. It
is thin, but firm ; it forms the upper portion of the septum of
the nose, and, to complete the partition, it unites with the vomer
and with a plate of cartilage before. It is very often inclined
to one side, so that the nostrils are not of equal size.

At a small distance from this perpendicular plate, on each
side of it, the cellular portions originate from the lower surface
of the cribriform plates ; they extend from before backward,
and are as long as the ethmoid bone ; their breadth between
the eye and the cavity of the nose varies in different subjects,
from half an inch to more ; they extend downwards from the
root of the nose or from the cribriform plate, more than half
way to the roof of the mouth. Their external surface on each
side forms a part of the surface of the orbit of the eye, and is
called 05 planum ; their internal surface forms part of the
external lateral surface of each nostril. This surface extends
the whole depth of the nostril, from before backward ; but in
many skeletons it is extremely imperfect, owing to the great
brittleness of the bony plates of which it is composed. When
the bone is perfect, the uppermost half part of this internal
surface is uniformly flat, and rather rough ; but below it, about
the middle of the bone, a deep groove begins, which extends
downwards and backwards, to the posterior extremity ; this is

OS ETHMOIDES. 77

the upper channel or meatus of the nose. The edge of the
surface immediately above it projects in a small degree over
this channel or groove ; having been described by Morgagni, it
bears his name, and may be considered as one of the"~^pongy
or turbinated bones ; from its situation, it should be called the
first or superior. The groove is very deep, and most of the cells
of the posterior part of the ethmoid bone communicate with it,
through one or more foramina at its anterior extremity.

The part of the surface of the ethmoid which is immediately
below this groove, is convex ; that which is before and below
it, is rather flat ; the convex part is the middle spongy or
turbinated bone, as it has commonly been called ; it projects
obliquely into the cavity of the nose, and hangs over the middle
channel or meatus, which is immediately below the ethmoid
bone. The internal surface of this spongy bone, which is
opposite the septum of the nose, is convex and rough or spongy ;
the external surface is concave. The anterior cells of the
ethmoid, and particularly those which the frontal sinuses on
each side communicate with, open into the middle channel or
meatus, under the anterior end of this turbinated bone.

This middle channel or meatus, is much larger than that
above ; it extends from the anterior to the posterior part of the
nostrils, and slopes downwards and backwards. The cavity of
the upper maxillary bone, or the antrum highmorianum, opens
on each side into this meatus, and a thin plate of bone extends
from the cellular part of the ethmoid so as to cover a part of it.

The cellular portions of the ethmoid are composed of plates
thinner than the shell of an egg ; they are entirely hollow, and
the cells are very various, in number, size, and shape. Some
cells of the uppermost row communicate with those of the
os frontis, formed by the separation of the plates of the orbitar
process of that bone.

From the posterior part of the cribriform plate, where it is
in contact with the lesser wings of the sphenoidal bone, thin
plates of bone pass down upon the anterior surface of the body
of the os sphenoides, one on each side of the azygos process,
and often diminish the opening into the sphenoidal cells.
These plates are sometimes triangular in form, the basis uniting
7*

78 OS ETHMOIDES.

with the cribriform plate. They have been described very
differently by different authors, some considering them as
belonging to the os ethmoides, and others to the sphenoid bone.
To the perfect ethmoid bone there are attached two triangular
pyramids, in place of the triangular bones; these pyramids are
hollow, the azygos process of the os sphenoides is received
between them ; one side of each pyramid applies to each side
of the azygos process, another side applies to the anterior
surface of the body of the sphenoid bone, in place of the ossa
triangularia, and the third side is the upper part of one of the
posterior nares.*5 There are two apertures in each of these

* This may be considered as an original observation of the lamented "Wistar.
The merit of it has been denied to him, more particularly by the anatomists of
Paris, under an impression that he had been anticipated in it by Berlin, who
has written an excellent and minute treatise on osteology. The extent to which
the claims of other anatomists interfere with his, he was fully aware of; and it
will be seen by the following communications to the American Philosophical
Society, that these are placed in as important a light as they deserve, at the
same time that he vindicates his own pretensions, to have first observed the
" cornets sphenoidaux " in the form of triangular hollow pyramids, as consti-
tuting part of the perfect ethmoid bone. — H.

Observations on those Processes of the Ethmoid Bone which originally form the Sphe-
noid Sinuses. By C. Wistar, M. D., President of the Society, Professor of
Anatomy in the University of Pennsylvania. — Read, Nov. 4, 1814.
It has been long believed that the sinuses, or cavities in the body of the os
sphenoides, were exclusively formed by that bone, when Winsl6w suggested
that a small portion of the orbitar processes of the ossa palati contributed to
their formation.*

Many year's after Winslow's publication, Monsieur Berlin described two
bones which form the anterior sides of these sinuses, and contain the foramina
by which they communicate with the nose.f

These bones he denominates "Cornets Sphenoidaux," and states that they
are most perfect and distinct between the ages of four years and twenty ; that
they are not completely formed before this period, and that after it they appear
like a part of the sphenoidal bone.— According to his account they are lamina of
a triangular form, and are originally in contact with the anterior and inferior
surface of the body of the os sphenoides, so that they form a portion of the sur-
face of the cavity of the nose. — He believed, that as they increase in size, they
become convex and concave, and present their concave surfaces to the body of
the sphenoidal bone, which also becomes concave, and presents its concavity to
those bones; thus forming the sinuses.

* In his description of the Ossa Palati, printed in the Memoirs of the Academy of
Sciences for 1720.

t See Memoirs of the Academy of Sciences for 1774.

t Cr f

^/t Vr^^^*^

OS ETHMOIDES. 79

pyramids ; one at the base opening directly into the nose, near
the situation of the opening of the sphenoida). sinuses, in the
bones of adults ; and the other in each of the sides in contact
with the azygos process. './

This account of M. Berlin has been adopted by Sabatier, and also by Boyer,
who has improved it by the additional observation, that these triangular bones
are sometimes united to the ethmoid, and remain attached to that bone when it
is separated from the os sphenoides. Bichat and Fyfe have confirmed the
description of Boyer.

The specimens of ethmoid and sphenoid bones, herewith exhibited to the
society, will demonstrate that in certain subjects, about two years of age, there
are continued from the posterior part of the cribriform plate of the ethmoid, two
Hollow Triangular Pyramids, which, when in their proper situations, receive be-
tween them the azygos process of the os sphenoides.— (See Plate X. Figures 1,
2, 3, with the explanation.)

The internal side of each of these pyramids applies to the aforesaid azygos
process ; the lower side of each forms part of the upper surface of the posterior
nares ; the external side at its basis is in contact with the orbit ar process of the
os palati. The base of each pyramid forms also a part of the surface of the
posterior nares, and contains a foramen which is ultimately the opening into the
sphenoidal sinus of that side.

In the sphenoidal bones, which belong to such ethmoids as are above described,
there are no cells or sinuses ; for the pyramid of the ethmoid bones occupy their
places. The azygos process, which is to become the future septum between the
sinuses, is remarkably thick, but there are no cavities or sinuses in it.

The sides of the pyramids, which are in contact with this process, are ex-
tremely thin, and sometimes have irregular foramina in them, as if their osseous
substance had been partially absorbed.* That part of the external side of the
pyramid which is in contact with the orbitar process of the os palati is also thin,
and sometimes has an irregular foramen, which communicates with the cells of
the aforesaid orbitar process.

Upon comparing these perfect specimens of the ethmoid and sphenoidal bones
of the subject about two years of age, with the os sphenoides of a young subject
who was more advanced in years, it appears probable that the azygos process
and the sides of the pyramid applied to it, are so changed, in their progress of
life, that they simply constitute the septum between the sinuses ; that the exter-
nal side of the pyramid is also done away, and that the front side and the basis
of the pyramid only remain ; constituting the Cornets Sphenoidaux f of M.
Berlin.

If this be really the case, the origin of the sphenoidal sinuses is very intel-
ligible.

*

* See e, Fig. 3.

t " Cornet" is the word applied by several French anatomists to the Ossa Turblnati of
the nose ; they seem to have intended to express by it a convoluted lamina or plate of bone.

The fine drawing of the Ethmoid Bone, for this plate was done by my friend M. Lesueur,
•whose talents are so conspicuous in the plates attached to Peron's " Voyage de Descou-
vertes aux Terres Australes.

80 OS SPHENOIDES.

.»

Os Sphenoides.

The os sphenoides or pterygoideus, resembles a bat with its
wings extended. It consists,

/ 1st. Of a body with two processes arising from it, called the
lesser wings, or apophyses of Ingrassias.

2dly. Of two large lateral processes, called the greater wings,
or temporal processes ; and,

3dly. Of two vertical portions, denominated pterygoid pro-
cesses.

The body is situated near the centre of the cranium, and in
contact with the cuneiform process of the occipital bone ; the
greater wings extend laterally between the frontal and temporal
bones as high as the parietal ; while the pterygoid processes
pass downwards on each side of the posterior opening of the
nose, as low as the roof of the mouth. It is, therefore, in
contact with all the other bones of the cranium, and with many
bones of the face.

The body has a cubic figure ; its upper surface forms a portion
of the basis of the cranium ; its lower and anterior surfaces form

/ Explanation of the Figures in the Plate referred to above.

FIG. I.

Represents the upper surface, or cribriform plate of the Ethmoid Bone.
a. CristaGalli.
bbbb. Cribriform plate.
c. Surface denominated Os Planum.
d d. Hollow Triangular Pyramids.

e. Space between the Pyramids for receiving the Azygos Process of the Os
Sphenoides.

FIG. II.

A lateral View of the Bone.
a. Crista Galli.

c. Os Planum.

d. Triangular Pyramid.

FIG. III.

The Bone Inverted.
a. The Nasal Plate of the Ethmoid Bone, which constitutes the upper portion

of the Septum of the nose.
g g. Those portions of the Ethmoid which are called Superior Turbinated

Bones.

//. The Cellular Lateral Portions of the Bone.
d d. The Triangular Pyramids.

e. Space between the Pyramids for the Azygos Process of the Os Sphenoides
— a foramen on the internal side of one of the Pyramids.

s

i

OS SPHENOIDES. 81

part of the cavity of the nose ; the posterior surface is articu-
lated with the cuneiform process of the occipital bone ; and
laterally it is extended into the great wings, or temporal processes.
On the upper surface of the body, the lesser wings^br the
apophyses of Ingrassias,* project from the lateral and anterior
parts ; these wings consist of two triangular plates, each of
Fig. 18.f which is joined to the

other by its base, and
to the body of the os
sphenoides by its un-
der surface near the
base, and terminates
in a point ; their direc-
tion is forwards and
outwards, and their flat
surfaces are horizontal. Anteriorly they are connected by
suture to the ethmoid and frontal bones ; their posterior edge
is rounded, and detached from any other bone, forming the
upper margin of the foramen lacerum of the orbit of the eye ;
this edge is thick and prominent at its internal extremity, and
these prominences are called the anterior or clinoid processes ;

* A physician of Palermo, who died in 1580, aged 70. — H.

f The superior or cerebral surface of the sphenoid bone. 1. The processus
olivaris. 2. The ethmoidal spine. 3. The lesser wing of the left side. 4. The
cerebral surface of the greater wing of the same side. 5. The spinous process.
6. The extremity of the pterygoid process of the same side, projecting down-
wards from the under surface of the body of the bone. 7. The foramen opticum.
8. The anterior clinoid process. 9. The groove by the side of the Sella Turcica,
for lodging the internal carotid artery, cavernous plexus, cavernous sinus, and
orbital nerves. 10. The Sella Turcica. 11. The posterior boundary of the Sella
Turcica ; its projecting angles are the posterior clinoid processes. 12. The
basilar portion of the bone. 13. Part of the sphenoidal fissure. 14. The foramen
rotundum. 15. The foramen ovale. 16. The foramen spinosum. 17. The
angular interval which receives the apex of the petrous portion of the temporal
bone. The posterior extremity of the Vidian canal terminates at this angle.
18. The spine of the spinous process ; it affords attachment to the internal lateral
ligament of the lower jaw. 19. The border of the greater wing and spinous
process which articulates with the anterior part of the squamous portion of the
temporal bone. 20. The internal border of the spinous process, which assists
in the formation of the foramen lacerum basis cranii. 21. That portion of the
greater ala which articulates with the anterior inferior angle of the parietal bone.
22. The portion of the greater ala which articulates with the orbital process of
the frontal bone.

82 OS SPHENOIDES.

immediately before them are the optic foramina, which pass
obliquely through the wings into the orbit of the eye, and
transmit on each side the optic nerve and a small artery.

Behind the optic foramen is a notch and sometimes a foramen,
made by the carotid artery. When the notch is converted into
a foramen, it is by a small bony pillar being extended from the
anterior clinoid process, to the body of the sphenoid. A groove
made by the optic nerves, is cften seen extending across the
body of the bone, from one of the optic foramina to the other.
Behind it is a depression, which occupies the greatest part of this
surface of the bone, in which the pituitary gland is lodged ; the
back part of this depression is bounded by a transverse emi-
nence, called the posterior clinoid process. These three pro-
cesses are called clinoid from their supposed resemblance to the
supporters of a bed ; and the depression for the pituitary gland
is called sella turcica from its resemblance to the saddle used by
the Turks.

On each side of the posterior clinoid process is a groove in
the body of the bone, made by the carotid artery as it passes
from the foramen caroticum of the temporal bone. The posterior
surface of the body of the sphenoides is rough, for articulation
with the truncated end of the cuneiform process of the os
occipitis.

On the anterior and inferior surfaces is a spine, called the
azygos process, or rostrum which is received into the base of
the vomer, and extends forward until it meets the nasal plate of
the ethmoid bone ; on each side of this spine, in the anterior
surface, are the orifices of the sphenoidal cells. Those orifices
appear very differently in different bones ; in some very perfect
specimens, they are irregularly oval, being closed below and
on their external sides, by the processes of the ossa palati, and
above by the triangular plates, as they have been called, of
the ethmoid bone. The cells or sinuses, to which these
orifices lead, occupy the body of the sphenoidal bone ; they are
divided by a partition, and each of them has a communication
with the cavity of the nose on its respective side, by the orifice
above described. The sinuses do not exist during infancy ;
they increase in the progress of life, and are very large in old age.

OS SPHENOIDES. 83

Laterally, the body of the sphenoides is extended into the
portions called the great wings or temporal processes. These
great wings compose the largest part of the bone, and their
internal surface forms a portion of the middle fossa of the/ base
of the cranium. Externally, the surface of each great wing is
divided into two portions : one of which is lateral, and unites
to the frontal, temporal, and malar bones, forming part of the
smooth surface for the temporal muscle ; the other portion
forms part of the orbit of the eye, and is very regular and
smooth. As the ethmoid bone forms part of the inside, this
portion of the great wing forms part of the outside of the orbit,
and is termed the orbitary process of the sphenoid bone. The
horizontal part of each wing terminates in an acute angle
termed spinous process, which penetrates between the petrous
portion and the articulating cavity of the temporal bone. In
this angle is the foramen for the principal artery of the dura
mater ; near the point of the angle is a small process, which
projects from the basis of the cranium, and is called styloid.

Fig. 19.* The pterygoid pro-

cesses pass downwards in
a direction almost per-
pendicular to the base of
the skull. Each of them
has two plates, and a
middle fossa facing back-
wards ; to complete the
comparison, they should
be likened to the legs of the bat, but are inaccurately named
pterygoid, or wing-like processes. The external plates
are broadest, and the internal are longest. From each side of

* The antero-inferior view of the sphenoid bone. 1. The ethmoid spine.
2. The rostrum. 3. The sphenoidal spongy bone, partly closing the left opening
of the sphenoidal cells. 4. The lesser wing. 5. The foramen opticum piercing
the base of the lesser wing. 6. The sphenoidal fissure. 7. The foramen rotun-
dum. 8. The orbital surface of the greater wing. 9. Its temporal surface. 10.
The pterygoid ridge. 11. The pterygo-palatine canal. 12. The foramen of
entrance to the Vindian canal. 13. The internal pterygoid plate. 14. The
hamular process. 15. The external pterygoid plate. 16. The foramen spino-
sum. 17. The foramen ovale. 18. The extpemity of the spinous process of
the sphenoid.

84 FORAMINA OF THE SPHENOIDAL BONE.

the external plates the pterygoid muscles take their rise. At
the root of each internal plate, a small hollow may be remarked,
where the musculus circumflexus palati rises, and part of the
cartilaginous end of the Eustachian tube rests. At the lower
end of the plate is a hook-like process (hamulus) round which
the tendon of the last named muscle plays, as on a pulley. The
ossa palati, on each side, rest upon these internal plates ; and,
therefore, the pterygoid processes seem to support the whole
face.

Foramina of the Sphenoidal Bone.

Before these foramina are described, it is necessary to state, that the nerves of
the brain are named numerically, beginning with the olfactory, which is
foremost.

It should also be observed, that each nerve of the fifth pair is divided, before it
passes from the cavity of the cranium, into three large branches.

The first foramina are the optic, which have been already
described; they transmit the optic, or second pair of nerves,
and a small artery, to the ball of the eye.

The second foramen, on each side, is the foramen lacerum.
It commences largely at the sella turcica, and extends laterally
a considerable distance, until it is a mere fissure. The upper
margin of this foramen is formed by the anterior clinoid
processes, and the edges of the smaller wings of the sphenoid
bone. This foramen transmits the third, fourth, and sixth pair
of nerves, and the first branch of the fifth pair, to the muscles,
and the other parts, subservient to the eye.

The foramen rotundum, or third hole, is round ; as its name
imports. It is situated immediately under the foramen lacerum,
on each side, and transmits the second branch of the fifth pair
of nerves to the upper maxillary bone.

The foramen ovale is the fourth hole. It is larger than the
foramen rotundum, and half an inch behind it. It transmits the
third branch of the fifth pair of nerves to the lower jaw.

The fifth hole is the foramen spinale. It is small and round,
and placed in the point of the spinous process, behind the fora-
men ovale, to transmit the principal artery of the dura mater,
which makes its impression upon the parietal bone.

THE fACE. 85

The sixth foramen is under the basis of each pterygoid
process, and is therefore called the pterygoid, or the Vidian*
foramen. It is almost hidden by the point of the petrous
portion of the temporal bone, and must be examined m the
separated bone. It is nearly equal in size to the spinous
hole.

This foramen transmits a nerve that does not go out from
the cavity of the skull, but returns into it. The second branch
of the fifth pair, after passing out of the cranium, sends back,
through this foramen, a branch called the Vidian, which upon
its arrival in the cavity of the cranium, enters the temporal bone
by the foramen innominatum.

Of the Face.

The face is the irregular pile of bones composing the front
and under part of the head, and is divided into the upper and
lower maxillae, or jaws.

The upper jaw consists of six bones on each side, of one
single bone placed in the middle, and of sixteen teeth.

The thirteen bones are, two ossa maxillaria superiora, two
ossa nasi, two ossa unguis, two ossa malarum, two ossa palati,
two ossa spongiosa inferiora, and the vomer.

The ossa maxillaria superiora form the principal part of the
cavity of the nose, with the whole lower and forepart of the
upper jaw, and a large proportion of the roof of the mouth.

The ossa nasi are placed at the upper and front part of the
nose.

The ossa unguis are at the internal angles of the orbits of
the eyes.

The ossrt palati in the back part of the palate, extending
upwards to the orbits of the eyes.

The ossa spongiosa in the lower part of the cavity of the
nose ; and

The vomer in the partition which separates the two nostrils.

* From its reputed discoverer, Vidius, a professor at Paris,
8

86 OSSA MAXILLARIA SUPERIORA.

Ossa Maocillaria Superiora.

The ossa maxillaria superiora, or upper jaw bones, may be
considered as the basis or foundation of the face ; as they form
a large part of the mouth, the nose, and the orbit of the eye.

The central part of each bone, which may be considered as
its body, is hollow, and capable of containing, in the adult,
near half an ounce of fluid. . The plate which covers this
cavity is the bottom of the orbit of the eye. The sockets of
the large teeth are below it. The roof of the mouth projects
laterally from the inside of it. A process for supporting the
cheek bone is on the outside ; and another process goes up
before it, which forms the side of the nose.

Fig. 20.* In each upper maxillary bone the fol-

lowing parts are to be examined :

The nasal process ; the orbitar plate ;
the malar process ; the alveolar process ;
the palatine process ; the anterior and
posterior surfaces ; the great cavity ; the
internal or nasal surface ; and the three
foramina.

The nasal process, which extends
upwards to form the side of the nose,
is rather convex outwards, to give the
nostril shape. Its sides above support
the nasal bone ; and a cartilage of the
alae nasi is fixed to its edge below.

The margin of the orbit of the eye is marked by a sharp
ridge on the external surface of this process ; and the part

* The superior maxillary bone of the right side, as seen from the lateral
aspect. 1. The external, or facial surface ; the depression in which the figure
is placed is the canine fossa. 2. The posterior, or zygomatic surface. 3. The
superior, or orbital plate or surface. 4. The infra-orbital foramen : it is situated
immediately below the number. 5. The infra-orbital canal, leading to the infra-
orbital foramen. 6. The inferior border of the orbit. 7. The malar process.
8. The nasal process. 9. The concavity forming the lateral boundary of the
anterior nares. 10. The nasal spine. 11. The incisive, or myrtiform fossa.
12. The alveolar process. 13. The internal border of the orbital surface, which
articulates with the ethmoid and palate bones. 14. The concavity which articu-
lates with the lachrymal bone, and forms the commencement of the nasal duct.
15. The palate process, t. The two incisor teeth, c. The canine, b. The two
bicuspidati. m. The three molares.

OSSA MAXILLARIA SUPERIORA. 87

posterior to this ridge is concave to accommodate the lachrymal
sac.

The orbitar plate, which covers the great cavity, and forms
the bottom of the orbit, is rather triangular in form, arid con-
cave. In the posterior part is a groove or canal, which pene-
trates the substance of the bone, as it advances forward, and
terminates in the infra-orbitary foramen, below the orbit. At
the place where this plate joins the nasal process above men-
tioned, viz. at the inner angle of the orbit, is the commencement
of the bony canal, which transmits the lachrymal duct into the
cavity of the nose.

The malar process projects from the external and anterior
corner of the orbitar plate ; it supports the malar bone, and is
rough for the purpose of articulating with it.

The alveolar processes compose the inferior and external
margins of the upper maxillary bones. When these bones
are applied to each other, they form more than a semicircle :
their cavities contain the roots of the teeth, and correspond
with them in size and form. They do not exist long before
the formation of the teeth commences ; they grow with the
teeth ; and when these bodies are removed, the alveoli dis-
appear.

The palate process is a plate of bone, which divides the nose
from the mouth, constituting the roof of the palate, and the floor
or bottom of the nostrils. It is thick where it first comes off
from the alveolar process ; it is thin in its middle ; and it is
again thick where it meets its fellow of the opposite side. At
the place where the two upper jaw bones meet, the palate plate
is turned upwards, so that the two bones are opposed to each
other in the middle of the palate, by a broad flat surface, which
cannot be seen but by separating the bones. This surface is so
very rough, that the middle palate suture almost resembles the
sutures of the skull ; and the maxillary bones are neither easily
separated, nor easily joined again. The meeting of the palate
plates by a broad surface, makes a rising, or sharp ridge,
towards the nostrils ; so that the breadth of the surface by
which these bones meet, serves a double purpose ; it joins the

88 OSSA MAXILLARIA SUPERIORA.

bones securely, and it forms a small ridge upon which the edge
of the vomer, or partition of the nose, is planted. Thus we
find the palate plates of the maxillary bones conjoined, forming
almost the whole of the palate ; while what properly belongs to
the palate bones forms a very small share of the back part only,

As these thinner bones of the face have no medulla, they are
nourished by their periosteum only, and are of course perforated
with many small holes.

The anterior, external or facial surface of the upper maxil-
lary bone is concave ; the margin formed by the lower edge of
the orbit, by the malar process, and by the alveolar processes,
being more elevated than the central part, which consists of a
depression called \\\Q fossa canina, which gives attachment to
two muscles, the compressor nasi, and levator anguli oris. At
a small distance below the orbit is the infra-orbitary foramen
for transmitting a branch of the superior maxillary nerve.
When these two bones are applied to each other, and the ossa
nasi are in their places, they form the anterior orifice of the
nasal cavity, which has a small resemblance to the inverted
figure of the heart on cards. — The concave border of the open-
ing of the nostrils, is projected forwards at its lower surface
into a sharp process, forming with a similar process at the oppo-
site side the nasal spine. Beneath the nasal spine, and above
the two superior incisor teeth, is a slight depression called the
incisive or myrtiform fossa, which gives origin to the depressor
labii superioris alaeque nasi muscle — .

The posterior zygomatic surface has been called a process
or tuber. The tuberosity is pierced by a number of small
foramina, giving passage to the posterior dental nerves, and
branches of the superior dental artery. It expands to a con-
siderable size, and is united internally and posteriorly to the ossa
palati. The great cavity extends from the bottom of the orbit
of the eye to the roof of the mouth, and from the anterior to
the posterior surface of the bone ; it opens in the cavity of
the nose, and is called antrum maxillare, or Highmorianum.*
There is but a small portion of bone between this cavity

* After an anatomist who described it.

OSSA NASI. 89

and the sockets of the teeth, particularly those of the second
molar tooth ; occasionally the fangs of the tooth enter the cavity.

The internal or nasal surface of this bone forms a large part
of the cavity of the nose, and is concave. At the roof of the
nasal process is a ridge, for supporting the anterior end of the
lower turbinated bone. The nasal process seems continued
into the cavity of the nose, and forms a portion of the orifice
of the canal for the lachrymal duct, which is on the external
side of this cavity, near its anterior opening, and under the
lower furbinated bone. The orifice in this bone by which the
antrum maxillare communicates with the nose, is very large ;
but it is reduced to a small size, by a plate from the ethmoid
bone, by a portion of the os palati, and of the lower spongy
bone, each of which covers a part of it.

The three foramina are, 1st. The infra-orbitary foramen
already described. 2d. The foramen incisivum or anterior
palatine hole, which passes through the palatine process, from
the nose to the mouth. In the nose it forms generally two
foramina, which unite and form but one in the mouth, imme-
diately behind the middle incisor teeth. This foramen is
closed by the soft parts during life, and transmits a branch of
the spheno-palatine nerve from each side, which runs on the
septum narium, and joining at the lower part of the canal with
its fellow, they unite, and, according to M. Cloquet,* form a
ganglion. 3d. The posterior palatine foramen, which is formed
by this bone, and by the os palati, on each side, is situated in
the suture which joins them to each other, and transmits to the
palate a branch of the upper maxillary nerve.

This bone is united to the frontal, nasal, unguiform, ethmoid
and malar bones, above ; to the ossa palati behind ; to the cor-
responding bone, on the opposite side ; and to the inferior spongy
bone, in the cavity of the nose.

Ossa Nasi.
The ossa nasi are so named from their prominent situation

* This ganglion, though it varies in size, is readily found. I always exhibit
it in the course of my lectures. — p.

8*

90 OSSA UNGUIS.

at the root of the nose. They are each of an irregular oblong
figure, being broadest at their lower end, narrowest near the
middle, and larger again at the top, where the edge is rough
and thick, and their connexion with the os frontis is conse-
quently very strong. They are convex externally, and concave
within. The lower edges of these bones are thin and irregular.
Their anterior edges are thick, and their connection with each
other, by means of their edges, is firm ; the suture between
them, extending down the middle of the nose, forms a promi-
nent line on the internal surface, by which they are united to
the septum narium. The uppermost half of their posterior
edges is covered by the edges of the nasal processes of the
upper maxillary bones ; the lower half laps over the edges of
these bones ; and by this structure they are enabled to resist
pressure. [On the posterior surface of the os nasi is a groove
occupied in the recent subject by a branch of the ophthalmic
nerve called the nasal, which enters the nose through the fora-
men orbitare internum anterius.] They are joined above to the
os frontis ; before, to each other ; behind, to the upper maxillary
bones ; below, to the cartilages ; and internally, to the septum of
the nose.

Ossa Unguis, or Ossa Lachrymalia.

The ossa unguis are so named from their resemblance to a
nail of the finger. They are situated on the internal side of the
orbit of the eye, between the os planum of the ethmoid, and
the nasal process of the upper maxillary bone. Their external
surface is divided into two portions, by a middle ridge ; the
posterior portion forms part of the orbit ; and the anterior, which
is very concave, forms part of the fossa and canal, for contain-
ing the lachrymal sac and duct. This portion is perforated
by many small foramina ; and the whole, being extremely thin
and brittle, is therefore often destroyed by the preparation of the
subject.

The internal surface of this bone is generally in contact with
the cells of the ethmoid ; a small portion of the anterior parts is
in the general cavity of the nose. Each os unguis is joined

OSSA MALARUM. 91

above to the frontal bone ; behind to the os planum ; before

and below to the maxillary bone. It sometimes is extended

into the nose, as low as the upper edge of the inferior spongy
bone.

Ossa Malarum.

The ossa malarum are the prominent square bones which
form the cheek, on each side. Before, their surface is convex
and smooth ; backward, it is unequal and concave, for lodging
part of the temporal muscles.

The four angles of each of these bones have been reckoned
as processes. The one at the external canthus of the orbit
called the superior orbitar process, is the longest and thickest,
The second terminates near the middle of the lower edge of
the orbit in a sharp point, and is named the inferior orbitar
process. The third, placed near the lower part of the cheek,
and thence called maxillary, is the shortest and nearest to a
right angle. The fourth, which is called zygomatic, because it
is extended backwards to the zygoma of the temporal bone,
ends in a point, and, has one side straight and the other sloping.
Between the two orbitar angles there is a concave arch, which
makes about a third of the external circumference of the orbit,
from which a fifth process is extended backwards within the
orbit, to form near one-sixth of that cavity ; and hence it may
be called the internal orbitar process. From the lower edge
of each of the ossa malarum, which is between the maxillary
and zygomatic processes, the masseter muscle takes its origin.

On the external surface of each cheek bone, one or more
small holes are commonly found for the transmission of small
nerves or blood-vessels from, and sometimes, into the orbit.
On the internal surface are the holes for the passage of the
nutritious vessels of these bones. A notch, on the outside of
the internal orbitar process of each of these bones, assists to
form the great slit common to this bone, and to the sphenoid,
maxillary, and palate bones.

The substance of these bones is, in proportion to their bulk,
thick, hard, and solid, with some cancelli.

92 OSSA PALATI.

Each of the ossa malarum is joined, by its superior and
internal orbitar processes, to the os frontis, and the orbitar
process of the sphenoid bone; by the edge between the internal
and inferior orbitar processes, to the maxillary bone ; by the
side between the maxillary and inferior orbitar process, again
to the maxillary bone ; and by the zygomatic process to the os
temporis.

Ossa Palati.

The ossa palati form the back part of the roof of the mouth,
and extends from it along the external sides of the posterior
openings of the nose, into the orbits of the eyes. Each bone
may therefore be divided into four parts, the palate square bone,
or palatine, or horizontal process, the pterygoid process or
tuberosity, the nasal lamella or perpendicular plate, and the
orbitar process.

The square bone is irregularly concave, for enlarging both
the mouth and cavity of the nose. The upper part of its
internal edge rises in a spine, after the same manner as the
palate plate of the maxillary bone does, to be joined with the
vomer. Its anterior edge is unequally ragged, for its firmer
connexion with the palate process of the os maxillare. The
internal edge is thicker than the rest, and of an equal surface.
for its conjunction with its fellow of the other side. Behind,
this bone is somewhat in form of a crescent, and thick, for the
firm connexion of the velum pendulum palati ; the internal
point being extended backwards, to afford origin to the palato-
staphylinus or azygos muscle. This square bone is well dis-
tinguished from the pterygoid process by a perpendicular fossa,
which, applied to a similar one in the maxillary bone, forms a
passage (ptery go-maxillary) for the palatine branch of the fifth
pair of nerves ; and by another small hole behind this, through
which a twig of the same nerve passes.

The pterygoid process is somewhat triangular, having a
broad base, and ending smaller above. The back part of this
process has three fossae formed in it ; the two lateral receive
the ends of the two pterygoid plates of the sphenoid bone ; the

OSSA PALATI. 93

Fig. 20.* middle fossa, which is very superficial,

makes up a part of what is commonly
called the fossa pterygoidca. The foreside
of this pterygoid process is rotf^h and
irregular where it joins the back part of
the great tuberosity of the maxillary bone.
Frequently several small holes may be
observed in this triangular process, par-
ticularly one near the middle of its base,
which a little above communicates with
the common and proper holes of this bone
already mentioned.

The nasal lamella of this bone is extremely thin and brittle,
and rises upwards from the upper side of the external edge of
the square bone, and from the narrow extremity of the ptery-
goid process ; it is so weak, and, at the same time, so firmly
fixed to the maxillary bone, as to be very liable to be broken
in separating the bones. From the part where the plate rises,
it runs up broad on the inside of the tuberosity of the maxillary
bone, to form a considerable share of the sides of the maxillary
sinus, and to close up the space between the sphenoid and the
great bulge of the maxillary bone, where there would other-
wise be a large slit opening into the nostrils. On the middle
of the internal side of this thin plate, there is a transverse ridge,
continued from one which is similar to it in the maxillary bone

* A posterior view of the palate bone in its natural position ; it is slightly
turned to one side to obtain a view of the internal surface of the perpendicular
plate (2). 1. The horizontal plate of the bone; its upper or nasal surface.

2. The perpendicular plate or nasal lamella, seen on its internal or nasal surface.

3, 10, 11. The pterygoid process or tuberosity. 4. The broad internal border of
the horizontal or palatine process, which articulates with the similar process of
the bone of the other side. 5. The ridge which with a similar elevation of the
opposite bone forms the palate spine. 6. The horizontal ridge which gives
attachment to the inferior turbinated bone ; the concavity below this ridge forms
a part of the inferior meatus of the nose, and the concavity (2) above the ridge
forms a part of the middle and superior meatus. 7. The spheno-palatine fora-
men. 8. The orbital process of the bone. 10. The middle facet of the ptery-
goid process or tuberosity which forms the middle of the pterygoid fossa. The
fossae 11 and 3, articulate with the two pterygoid plates of the sphenoid bone:
11 with the internal, and 3 with the external.

94

OSSA PALATI.

for supporting the back part of the os spongiosum inferius.
Along the outside of this plate, the perpendicular fossa made
by the posterior palatine nerve is observable.

At the upper and posterior edge of this nasal plate is a notch,
which when applied to the sphenoid bone, forms the spheno-
palatine foramen, through which a nerve, artery, and vein pass
to the nostril ; this notch forms two processes on the posterior
part of the bone, the inferior of which is in contact with the
internal plate of the pterygoid process of the sphenoidal bone,
and has, therefore, been called by some French anatomists, the
pterygoid apophysisofthe ospalati. The superior and anterior
portion is the proper orbitar process of this bone, which is
Fig. 21.* situated at the posterior part of the lower
surface of the orbit, and forms a portion
of it. This process of the os palati is
hollow ; and its cavity generally com-
municates with the contiguous cell of the
os ethmoides. It has several surfaces,
one of which is to be found in the orbit,
and another in the zygomatic fossa.

The palate square part of the palate
bone, and its pterygoid process, are firm
and strong, with some cancelli ; but the
nasal plate, and orbitar processes, are very thin and brittle.

The palate bones are joined to the maxillary, by the fore
edges of the palate square bones ; by their thin nasal plates,
and part of their orbitary processes, to the same bones ; by
their pterygoid processes, and back part of the nasal plates, to

* The perpendicular plate of the palate bone seen upon its external or spheno-
maxillary surface. 1. The rough surface of this plate, which articulates with
the superior maxillary bone. 2. The posterior palatine canal, completed by the
tuberosity of the superior maxillary bone. The rough surface to the left of the
canal (2) articulates with the internal pterygoid plate. 3. The spheno-palatine
or lateral nasal foramen. 4, 5, 6. The orbital portion of the perpendicular plate.
4. The pterygoid apophysis or spheno-maxillary facet of this portion. 5. Its
orbital facet or process. 6. Its maxillary facet, to articulate with the superior
maxillary bone. 7. The sphenoidal portion of the perpendicular plate. 8. The
pterygoid process or tuberosity of the bone.

OSSA SPONGIOSA INFERIORA. THE VOMER. 95

the pterygoid processes of the os sphenoides ; by the transverse
ridges of their nasal lamellae to the ossa turbinata inferiora, and
by the spines of the square bones to the vomer. *j

j/n

The Ossa Spongiosa, or Turbinata Inferiora.

The ossa spongiosa, or turbinata inferiora, are so named to
distinguish them from the upper spongy bones, which belong
to the os ethmoides ; but these lower spongy bones are quite
distinct, and connected in a very slight way with the upper
jaw bones. They are rolled or convoluted, very spongy, and
exceedingly light. Each of them is attached to the os maxil-
lare superius, near the transverse ridge, by a hook-like process,
and covers a part of the opening of the maxillary sinus. One
end is turned towards the anterior opening of the nose, and
covers the end of the lachrymal duct ; the other end of the same
bone points backwards towards the throat. The curling plate
hangs down into the cavity of the nostril, with its convex side
towards the septum. This spongy bone differs from the spongy
processes of the ethmoid bone, in being less turbinated or
complex, and in having no cells connected with it.

The Vomer.

The vomer is a thin flat bone, which forms the back part of
the septum of the nose. Its posterior edge extends downwards
from the body of the os sphenoides to the palatine processes of
the ossa palati, separating the posterior nares from each other.

The figure of this bone is an irregular rhomboid. Its sides
are smooth ; and its posterior edge appears in an oblique
direction at the back part of the nostrils. The upper edge is
firmly united to the base of the sphenoid bone, and to the nasal
plate of the ethmoid. It is hollow for receiving the processus
azygos of the sphenoid, and where it is articulated to the nasal
plate of the ethmoid, it is composed of two lamina which
receive this plate between them. The anterior edge has a
long furrow in it, where the middle cartilage of the nose enters.
The lower edge is firmly united to the nasal spines of the
.-,

96 MAXILLA INFERIOR.

maxillary and palate bone. These edges of the bone are much
thicker than its middle, which is as thin as paper ; in conse-
quence of which, and of the firm union or connexion this bone
has above and below, it can very seldom be separated entire in
adults ; but in a child it is much more easily separated entire,
and its structure is more distinctly seen.

Its situation is not always perpendicular, but often inclined
and bent to one side, as well as the nasal plate of the ethmoid
bone.

It is united above to the os sphenoides and the nasal plate
of the ethmoid bone ; before to the middle cartilage of the
nose ; and below, to the ossa palati and ossa maxillaria supe-
riora.

Maxilla Inferior, or Lower Jaw.

The form and situation of this bone are so generally known,
that they do not require description. To acquire an accurate
idea of the lower jaw, it is, however, necessary to examine
attentively its different parts : viz. the chin, or mental protuber-
ance, the sides, the angles, and the processes.

In subjects where the bones are strongly marked, there
is a prominent vertical ridge in the middle and most inferior
part of the chin which becomes broad below so as to form a
triangle, and on each side of this triangular prominence are
transverse ridges ; from these eminences the muscles of the lower
lip originate.

On each side of the jaw, commonly under the second of the
bicuspides, or small molar teeth, is the anterior maxillary or
mental foramen, through which pass out branches of the
inferior maxillary nerve and blood-vessels.^ This foramen,
has a direction upward and backward. At a ?mall distance
behind these foramina, on each side, is the commencement of a
ridge which continues backward until it forms the edge of the
anterior or coronoid process. The alveolar processes, which
form the upper edge of the jaw, are on the inside of this ridge ;
the alveoli or sockets corresponding with the roots of the teeth,
in number and form. The lower edge of the jaw, which is

7^

:

MAXILLA INFERIOR. 97

denominated the base, is round and firm, except at the angles,
where it is thin.

The angle is formed at the posterior extremity of the base :
in children it is obtuse ; but in adults whose teeth are perfect,
it is nearly rectangular. The masseter muscle is inserted into
the lower jaw, at the angle ; and there are several inequalities
on the surface made by this muscle.

Fig. 22.* The anterior or coronoid

process, is rather higher than
the posterior, and forms an
obtuse point : into this process
the temporal muscle is inserted.
The anterior edge of the coro-
noid process is sharp, and con-
tinued into the rid^e above

O

mentioned ; from this edge the
buccinator muscle arises. As
the alveoli are on the inside of
this edge and ridge, the jaw is very thick at this place. There
is a semicircular or sigmoid notch between this coronoid process
and the posterior or condyloid ; and here the bone is very thin.

The condyles are oblong, and are placed obliquely ; so that
their longest axes, if extended until they intersect each other,
would form an angle of more than one hundred and forty
degrees. The neck of the process, or the part immediately
below the condyle, is concave on the anterior, arid convex on
the posterior surface.

On the inside of the jaw, in the middle of the chin, is a small
protuberance, sometimes divided by a vertical fissure ; to this
are attached the fraenum lingua, and some muscles of the
tongue and os hyoides. Farther back is a ridge called the
mylo-hyoid, which extends backwards and upwards, until it

* The lower jaw. 1. The body. 2. The ramus. 3. Thesymphysis. 4. The
fossa for the depressor labii inferioris muscle. 5. The mental foramen. 6. The
external oblique ridge. 7. The groove for the facial artery. 8. The angle. 9.
The extremity of the mylo-hyoidean ridge. 10. The coronoid process. 11. The
condyle. 12. The sigmoid notch. 13. The inferior dental foramen. 14. The
mylo-hyoidean groove. 15. The alveolar process. ». The middle and lateral
incisor tooth of one side. c. The canine tooth, b. The two bicuspides. m. The
three molares.

9

98 MAXILLA INFERIOR.

approaches the alveoli of the last molar teeth ; where it termi-
nates in an oblong protuberance. To the anterior part of this
line the mylo-hyoidei muscles are attached ; and to the posterior
extremity, the superior constrictor of the pharynx. The surface
of the bone above this ridge is smooth, and covered with the
gums and lining membrane of the mouth. The surface below
the posterior part of the line is rather concave, to accommodate
the submaxillary gland.

At a small distance behind the alveoli, and nearly on a line
with them, midway between the roots of the two processes, is
a large foramen, called the inferior dental, for transmitting the
third, or inferior maxillary branch of the fifth pair of nerves,
and the blood-vessels which accompany it ; the canal, which
commences here, terminates at the anterior foramen, already
described.* The surface of this canal is perforated by many
foramina, through which blood-vessels and nerves pass to the
different teeth, and to the cancelli of the bone. On the anterior
side of the foramen is a sharp-pointed process, from which a
ligament passes to the temporal bone. The nerve and vessels,
before they enter into this foramen, make an impression on the
bone ; and there is generally a small superficial groove called
the mylo-Jiyoid, which proceeds downwards from it, being made by
a small nerve which supplies some of the parts under the tongue.

At the angle of the jaw, on the inside, is a remarkable rough-
ness, where the internal pterygoid muscle is inserted.

The lower jaw moves like a hinge upon its condyles in the
glenoid cavity, when the mouth opens and shuts in the ordinary
way. When the mouth is opened very wide, the condyles move
forward upon the tubercles before the cavities : if the effort to
open the mouth is continued, the lower jaw is fixed in that
situation, and the whole head is thrown back, which separates
the upper jaw still farther from the lower.

The lower jaw can be projected forward without opening the
mouth, by the movement of both condyles, at the same time, on
the tubercles.

This bone can also rotate upon one condyle, as a centre, while

* A branch of this canal is continued forwards to the symphysis by which
the front teeth are supplied with vessels and nerves.— p.

THE TEETH.

99

the other moves out of the glenoid cavity, upon the tubercle :
but these important motions can be better understood, after the
muscles, and the articulation with the temporal bone, in its recent
state, have been described.

Fig. 23.

Of the Teeth.

In the adult, when the teeth are perfect, there are sixteen in
each jaw, and those in corresponding situations, on the opposite
sides, resemble each other exactly.

They are of four kinds, viz. incisores, or the fore teeth ; cuspi-
dati, or the canine ; bicuspides, or the small grinders ; and
molares, or the large grinders.

On each side of the jaw, supposing it divided in the middle
there are two incisores, one cuspidatus, two bicuspides, and three
molares. They occur in the order in which they have been
named, beginning at the middle of the jaw, as in the above
figure.

Each tooth is divided into two parts, viz. the body, or that
portion which is bare, and projects beyond the alveoli and gums ;
and the root, which is lodged in the socket. The boundary
between these parts, which is embraced by the gums, is called
the neck of the tooth.

The body and roots consist of a peculiar kind of bone (dentine)
which is more firm and hard than the substance of the other
bones ; but all the surface of the body, which projects beyond

100 COMPOSITION OF THE TEETH.

the gums, is covered with enamel, a substance very different from
common bone.

Every tooth in its natural condition has a cavity in it, which
commences at the extremity of each root, and extends from it to
the body of the tooth, where it enlarges considerably. This cavity
is lined by a membrane, and contains a nerve, with an artery
and vein, which originally entered the tooth, by a foramen near
the point of the root, as is evidenf during the growth of the teeth.
These vessels, and the nerve, have been traced into the teeth ;
although in many subjects the foramina appear to be closed up.
— A third substance has lately been discovered by Prof. Ret-
zius of Stockholm as entering into the..co'nGfyo£it]6n*of the teeth
of man, called the cortical substance or cementum. It com-
mences at the lower edge of the enamel and surrounds com-
pletely the fang. In many of the lower animals it is found also?
on the faces of the compound teeth, filling up the spaces between
the vertical ridges of enamel. —

Composition of the Teeth.

— The bone or ivory of the teeth, now called Dentine, (see
Fig. 24,) constitutes the whole of the root, and a greater part
of the body and neck. The cavity in the centre, for the lodg-
ment of the pulp, (cavitas pulpi) in whichever of the teeth it
is examined, presents an exact similarity of shape to the bodies
and fangs of the teeth, as though the latter had been moulded
upon the pulp. The ivory is of a polished pearly whiteness,
like that of a piece of white satin. It is composed chemically
both of animal and earthy matter, but in different propor-
tions from ordinary bone. If exposed for a considerable
Fig. 24. time to the action of a weak acid solu-

tion, the earthy matter is dissolved,
and there is left a flexible, tenacious,
dense, and homogeneous mass, much
resembling cartilage, but more dense.
If, on the contrary, it is exposed to the
action of fire, the animal matter is first
blackened, then consumed, and there
is left a white, hard, friable residue of calcareous matter.

COMPOSITION OF THE TEETH. 101

When examined with the microscope, the bone or ivory
appears to consist of minute branching fibres, which begin at the
pulp and run toward the periphery of the tooth, and aje im-
pacted in some homogenous bony tissue lodged between them.
— These fibres have been shown by Mr. Nasmyth to be nothing
more than little opaque bodies, the nuclei of the bone or ivory
cells arranged in a linear series.

— The enamel or vitreous substance, (see Fig. 24,) so named
from its resemblance to vitrified minerals, has been with
greater propriety called by Blake, the cortex striatum, from the
lines which it presents upon its sides. It forms a covering
nearly a line in thickness upon the crown of the teeth, and is
thinned down at its termination upon the neck. It is composed
of minute hexagonal crystalline fibres, consisting like those of
the ivory of minute cells filled with calcareous substance piled
one upon another, perpendicularly to the bony part, and so
closely compressed together, as to leave no obvious interval
between them. All the wear of the teeth takes place, therefore,
at the end of these fibres and not upon their sides ; and the
enamel is rendered by this arrangement much less liable to frac-
ture.

— No vessels have been traced to this substance, nor has it
ever been seen like the bony portion, colored by madder in
young animals fed on this substance during the development
of the teeth. But Mascagni, infatuated with his discoveries
in the absorbent system, absurdly regarded this substance as
entirely formed of absorbent vessels.* It is exceedingly hard
and strikes fire, on collision with steel. While covering the
bone, it presents a milky white appearance ; removed from it,
it is semi-transparent and opaline.

— The enamel is thickest on those parts of the teeth most
exposed to friction, as on the horizontal surfaces of the
grinders, the edges of the incisors, and the points of the cuspi-
dati. The position of the enamel and its arrangement into
fibres is well seen in Fig. 24.

* Vide Prodrome.
9*

102 PURKINJE AND MULLER ON THE TEETH.

— The enamel and ivory of the teeth are the most indestructible
after death of all parts of the body. In opening tumuli or other
ancient places of sepulchre, they are frequently found to have
undergone scarcely any decomposition.

— The cortical substance or cementum, see Fig. 24, consists of a
thin osseous layer developed on the external part of the fangs,
down to the orifices which lead to the cavity of the tooth. It is
essentially of the same structure as true bone, containing the
characteristic corpuscles, and calcigerous branching tubuli of
that tissue. It is supposed to be formed by ossification of the
capsule in contact with the fang, and is certainly the seat of the
exostosis often met with on the roots of the teeth. In old age it
makes its appearance in the cavity of the tooth, and is formed
from the membrane of the pulp — the pulp shrinking and retiring
in proportion as the cement accumulates.

— The chemical composition of the two substances of the hu-
man teeth, consists, according to Berzelius, in the hundred
parts, of

Enamel. Bone.

Animal matter, - 20.0

Phosphate of lime, with fluate of lime, 88.5 - 64.3

Carbonate of lime, 8.0 - 5.3

Phosphate of magnesia, - 1.5-1.0
Soda, with some chloride of soda, - 1.4

Free alkali and animal matter, 2.0

100.0 100.0

— Purkinje and Miiller, have recently, with the aid of the
microscope, investigated very minutely, the structure of the
teeth, and their discoveries have been confirmed by many
other observers of high reputation. They describe the bony
part of the tooth as consisting of fibres running parallel to each
other from the external to the internal surface of the tooth,
between which is placed a semi-transparent, homogeneous por-
tion. These fibres they believed to be really tubular; for on

PURKINJE AND MULLER ON THE TEETH. 103

bringing ink into contact with them, it was drawn into them,
as if by capillary attraction. These tubes Miiller believed to
be filled, at least partially, with calcareous matter, which was
the cause of the whiteness and opacity of the toofh. In
the more transparent part of carious teeth, the white sub-
stance in these tubes presented more of a granular, and less of
a compact appearance, under the microscope, than in a sound
tooth.

— The white color and opacity of these tubes were removed
by the application of acids. On breaking a thin lamella of a
tooth transversely in regard to the fibres, and examining the
edge of the fracture, he perceived the tubes, stiff, straight, and
inflexible, projecting here and there from the surfaces. If the
lamella had previously been acted on by acid, the tubes were
flexible, transparent, and often very long. Hence Miiller
inferred that the walls of the tubes have a basis of animal tissue,
and that besides containing calcareous matter in their cavity,
they have this tissue in the natural state impregnated with
calcareous salts. The greater part of the earthy matter of the
tooth is, however, contained in the transparent homogeneous
portion between the fibres, in which it can be rendered visible
in a granular state by boiling thin lamina of teeth in a ley of
potash.

— Purkinje, by the aid of high magnifying powers, discovered
the corpuscles that characterize true bone, in layers taken from
the external and internal surface of the root ; he considers the
great mass of the tooth, however, as destitute of organization. —
— These fibres which have been still more fully proved by
Retzius* to be true canals, having their own walls, are differ-
ently arranged in the separate substances of the tooth, but are
every where exceedingly minute. In the ivory they are about
g^th of a line in diameter: they commence by open orifices
at the cavity of the pulp, and extend in an undulating but
nearly parallel direction to the surface, dividing and branching

* Mikroskopiska Undersokningar ofver Tandernes sardeles Tandbenets,
struktur : Stockholm, 1837.

104 OF THE ALVEOLI.

in their course ; the branches anastomosing together, and com-
municating occasionally with very minute calcigerous cells,
lodged in the transparent intertubular structure, which may be
compared to the corpuscles of ordinary bone.

The fibres or filled tubes of the enamel are about 5£0th of a
line in diameter, and are hexagonal. They are striated,
arranged parallel to each other, and are applied by their
internal extremities to corresponding depressions on the surface
of the ivory.

— The ordinary bony tubuli of the cement or cortical substance
communicate here and there with the branching tubes of the
ivory.

— These minute but interesting details in regard to the structure
of the teeth, which are found to vary in the different classes of
animals, are important, not only as furnishing one of the best
methods of their classification, but in exhibiting the striking
analogy that exists, as to their structure, between teeth and
bone. The tubes or canals of common bone are occupied by
blood-vessels, the calcareous matters being lodged in the bony
corpuscles and their reticular tubuli ; while those of the teeth
are vascular in the growing state, and become nearly all
filled up as well as their corpuscles with earthy matter, to
give that great degree of solidity requisite in biting and masti-
cation.—

The alveoli or sockets of the teeth, are formed upon the edge
of the jaw : the bone, of which they consist, is less firm than
any other part of the jaws: they correspond exactly with the
roots of the teeth ; and are lined with a vascular membrane,
which serves as a periosteum to the roots, and assists in fixing
them firmly.

— They are developed pari passu, with the teeth, and solely
for the purpose of giving them a lodgment ; hence when the
teeth are removed from the jaw, in the living subject, the
sockets subsequently disappear by absorption, as being of no
further use. There are two sets of alveoli, one for the deci-
duous teeth of the child, and one for the permanent teeth of
the adult. Their walls are formed of one plate on the external

THE ALVEOLI. 105

side of the jaw, and one on the internal, with transverse bony
laminae passing between them. On the side of the cavity
which they form, their substance is loose and cellular ; on their
outer side, like other bones, they are smooth and compact:
— The transverse processes, are rather more prominent than the
lateral part of the parietes, corresponding in this respect inversely
with the line of enamel on the teeth.

— The enamel terminates on the neck of the teeth a little above
the level of the sockets, leaving a small space on the bony part
of the neck round which the gum is attached.
— The alveoli, terminate in as many hollow processes, as there
are fangs to the teeth which they lodge : and at the bottom of
each of these processes there are one or more minute foramina,
for the transmission of vessels and nerves to the internal mem-
brane and pulp of the teeth.

— The mode of articulation of the teeth in the sockets is called
gomphosis ; even in their perfect state, the teeth are slightly
movable in the socket, of which dental surgeons, occasionally
take advantage, in altering the direction of the teeth, by
mechanical means. The firmness of the articulation, depends
upon the adaptation in size and shape of the sockets to the
fangs, on the gum which surrounds the neck, of the periosteum
of the sockets which is continuous with that of the fangs, and
of the vessels and nerves which enter into the foramina of the
fangs.

The teeth of different kinds differ greatly from each other, in
form and size.

The body of the incisores is broad, with two flat surfaces,
one anterior and the other posterior ; the anterior surface is
rather convex and the posterior concave ; they meet in a sharp
cutting edge. At this edge the tooth is thinnest and broadest;
it gradually becomes thicker and narrower, as it is nearer the
neck. The enamel continues farther down on the anterior and
posterior surfaces than on the sides.

The incisores of the upper jaw are broader than those of the
lower ; especially the two internal incisores.

The cuspidati are longer than any other teeth, and are thicker

106 PERMANENT TEETH.

than the incisors. Their edges are not broad, as those of the
incisors, but pointed ; this point is much worn away in the pro-
gress of life.

The enamel covers more of the lateral part of these teeth
than of the incisors.

The bicuspides are next to the cuspidati, two on each side.
They resemble each other strongly ; but the first is smaller than
the other, although it generally* has a longer root. The bodies
are flattened laterally, but incline to a roundish form. On the
middle of the grinding surface are depressions which make the
edges prominent. On the external edge there is generally one
distinct point in each of the bicuspides. The internal edge is
lower than the external in the first bicuspis, which gives it a
resemblance to the cuspidatus. In the second bicuspis, the
internal edge is more elevated, although the point is not so
distinct as it is on the external edge.

The bicuspides have generally but one root, which is often
indented lengthwise, so as to resemble two roots united.

The three molares or large grinders are placed behind the
bicuspides, on each side. The first and second strongly resem-
ble each other, but the third has several peculiarities. The
body of the large grinders is rather square ; the grinding surface
has often five points, and three of these are on the external side.
In the upper jaw these teeth have three roots, two situated
externally, and one internally, which is very oblique in its
direction ; they are all conical in their form. It seems probable
that the roots of these teeth are arranged in this way to avoid
the antrum maxillare. The molares of the lower jaw have but
two roots, which are flat, and are placed one anterior and the
other posterior ; in each of these broad roots there are two
canals, leading to the central cavity ; whereas, in each root of
the upper molares there is but one. The third grinder is called
dens sapientia^ from its late appearance. It is shorter and
smaller than the others ; its body is rather rounder, and its roots
are not so regular and distinct ; for they are sometimes com-
pressed together, and sometimes there appears to have been
but one root originally, when the whole tooth has a conical

DECIDUOUS TEETH. - 107

appearance. In some cases the denies sapientiae take an
irregular direction, and shoot against the adjoining teeth.

Infants have a set of deciduous teeth, which differ in several
respects from those of adults. They are but twenty in ntfmber ;
the five on each side of each jaw, consist of two incisores, one
cuspidatus, and two molares or large grinders. The first of them
generally protrudes through the gums between the fourth and
eighth months of age ; the last about the end of the second year.
They commonly appear in pairs,* which succeed each other at
irregular intervals. Those of the lower jaw are, in most cases,
the first. The order of their appearance is this : the central
incisors appear first, then the external incisors on each side ;
after these the first molaris, then the cuspidatus, and finally
the last molaris on each side. There are many deviations
from this order of succession, but it takes place in a majority of
cases.

These deciduous teeth become loose, and are succeeded by
those which are more permanent, nearly in the same order in
which they appeared, but with a progress much more slow.
The incisores generally become loose between the sixth and
seventh year ; the first molares about the ninth, the cuspidati
and the second molares not until the tenth or twelfth, or even
fourteenth year. The bicuspides take the places of the infant
molares.

The three permanent molares appear in the following order :
the first of them protrudes a short time before the front teeth are
shed ; it is the first of the permanent teeth which appears,
and is seen between the sixth and seventh year. The second
molaris appears soon after the cuspidati and the second bicus-
pides are seen. There is then a long interval ; for the last
molaris or dens sapientise is seldom seen before the twentieth
year, and sometimes not until the twenty-fifth.

The teeth are formed upon pulpy substances, which are
situated in the alveoli, and are contained in capsules. A shell
of bone is first formed upon the surface of the pulp, which

* The two teeth of a pair do not appear at the same precise time, but very
near to each other.

108 DEVELOPMENT OF THE TEETH.

gradually increases, and the pulp diminishes within it. The
body of the tooth is produced first, and the root is formed
gradually afterwards ; during its formation the root has a large
opening at the extremity, which is gradually diminished to the
small orifice before described. The roots, as well as the body,
are formed upon the pulpy substance, which gradually
diminishes, as they increase. After the external surface of the
body of the tooth is formed* the enamel begins to appear
upon it, and gradually increases, until it is completely invested.
It is probable that the enamel is deposited upon the body of
the tooth by the membranous capsule which contains it. This
substance, which appears to be formed of radiated fibres, is
harder and less destructible than bone. Like the substance
of bone, it is composed of phosphate, with a small propor-
tion of the carbonate of lime; but it is destitute of the cartila-
ginous or membraneous structure which is demonstrable in
bone.

The pulpy substances, or rudiments of teeth, may be seen in
the foetus, when about four months old. At six months,
ossification can be seen to have commenced on the pulps of
the incisores. At the time of birth, the bodies of the infant
teeth are distinctly formed. The alveoli, at first, have the
appearance of grooves in the jaw, which afterwards are divided
by transverse partitions ; they enlarge, in conformity to the
growth of the teeth, and appear to be altogether influenced by
them.

The permanent teeth are formed very early : the rudiments
of the first permanent grinder on each side have commenced
their ossification at birth. At the same time, the rudiments of
the permanent incisors are to be perceived ; and their bodies
will be found nearly ossified, by the time the infant incisors
are protruded completely through the gums. About the age of
six years, if none of the infant teeth are shed, there will be
forty-eight teeth in the two jaws, viz : the twenty infantile,
and twenty-eight permanent teeth, more or less completely
formed.

— From their mode of development, apparent structure, and

.c *&f*

DEVELOPMENT OF THE TEETH. 109

connexions with the rest of the economy, the teeth were prior to
the microscopical researches above detailed considered analogous
to the hair, nails, and feathers of mammiferae and birds, and to
the shells of molluscae. It cannot be said that the teeih are
absolutely inorganized, that they are mere concretions of an
effused fluid, since there is no part appertaining to living beings,
entirely destitute of life ; but in the hard structure of the teeth,
no anatomist has yet demonstrated either vessels or nerves, though
there are practical dentists, who assert that they have seen blood
issu« from the bony part of the teeth, in some of their operations.*

* Hunter denies positively the existence of any vessels passing between the.
pulp and bone of the teeth, as he was not able to render them manifest by injec-
tion, as the coloring matter does not pass into them when animals are fed upon
madder, except in the forming state, and as they do not share in the general soft-
ening of the bones, in rickets and malacosteum. Blake believed that these
vessels did exist, but were difficult to demonstrate, like those that we know to
pass in the eye from the capsule of the crystalline lens, to the lens itself; Beclard,
that there were no vessels in the bone of the teeth, continuous with those of the
pulp, but that the former received continually from the latter a nourishing liquid
which penetrated it by imbibition, and that it was situated in regard to the pulp,
as the hair and nails to the vascular part of the skin. But the morbid altera-
tions which take place in the body of the teeth, the softening and exostosis seen
frequently at their roots, and the fusion of the latter occasionally to the bottom
of the alveoli, render their vascularity highly probable.

The fang of a perfectly developed tooth, is covered closely by a membrane,
called its periosteum, which is continuous with the periosteum of the socket, and
is on all hands admitted to be vascular ; the internal cavity is also lined by a
highly nervous and vascular membrane. Both of these are intimately con-
nected with the bony structure of the tooth, and require a little force to separate
them. This connection Mr. T. Bell believes to be made by vessels and probably
nerves, which pass between them and the bone. Though no artificial injection?
has been made of the teeth, this writer has seen them tinged with a bright yel-
low in a young woman who died of jaundice ; and where death has taken place
from hanging or drowning, when there is usually a congestion of the capillary
system, " he has found the osseous part colored with a dull deep red which could
not possibly take place if they were devoid of a vascular system ; in both
instances the enamel remained wholly free from discoloration." I have observed
the same thing in the teeth of subjects who have died of cholera. The existence
of nerves in the bony part of the teeth Bell considers manifested by the facts
common'y observed by dentists ; in filing the teeth no pain whatever is produced
till the. enamel is removed ; but the instant the file begins to act upon the bone,
the sensation is exceedingly acute : and when the gums, alveoli and periosteal
lining membrane, have receded from the teeth so as to leave the bony part bare,
it is exquisitely sensitive when touched with any hard instrument.

He admits likewise the existence of absorbents in the bony part of the teeth,
for in a tooth in which inflammation had existed for a considerable time, he
10

110 DEVELOPMENT OF THE TEETH.

— If the pulp which produces them be destroyed from any
cause, they lose the little vitality that they may possess, become
foreign bodies mechanically retained in the living parts, and
sooner or later are thrown off.

— The teeth are distinguished from the common bony tissue, by
the absence of any demonstrable cellular or vascular parenchyma
in their composition, by their being in part exposed to the
contact of the atmosphere, whiah no bone can be without losing
its vitality, by the enamel which covers them externally, by
their successive evolution and renovation at certain periods of
life, and lastly by their wearing out, and being lost in old age,
whilst the vital actions are still going on in the rest of the economy.
— In many of the lower animals the teeth are evidently a
production of the skin or dermoid tissue, which is reflected in
at the commencement of the digestive passages, and many
modern anatomists have for the reasons above mentioned, con-
nected them with the description of the digestive organs. They
have, however, again been restored for purposes of convenience
to the student, to their proper connexion with the bones in which
they are developed.

Development of the Teeth.

— The teeth, as we have before observed, are developed on a
principle different from that of other parts of the body, by
germs or gemmules. If the jaws of a foetus are examined with
care, even at the period of two months* after conception, an
extremely soft, jelly-like substance is seen lying in a groove
along the edge of each maxillary arch. At the third month it is
more consistent, and two plates of bone have sprung up at its
sides, which are the rudiments of the external and internal alveo-
lar plates. Shortly after this period, the pulpy substance sepa-
rates into distinct portions, and rudiments of the transverse plates
of the alveoli are seen shooting across, from side to side. These
distinct portions of the pulpy substance, have a papillary form
and are the germs or rudiments from which the teeth are devel-

found after its extraction an abscess in the very centre of the bony structure,
communicating with the natural cavity and filled with pus. — p.
* T. Bell.— Beclard.

DEVELOPMENT OF THE TEETH. Ill

oped ; each is partially enclosed in a sac, and receives branches
from the vessels and nerves which run along the bottom of the
groove. At the fourth month, the enveloping sac is thick in its
texture, and consists of two layers, which are easily separated
after a short maceration. Both of these layers, Fox and T. Bell
have proved, by their injections, to be vascular:* laying loosely
within this double sac is the gelatinous vascular pulp itself,
covered by an extremely thin, delicate vascular membrane, (to
which it is closely united by vessels,) which secretes the bony
part of the tooth, and is a sort of internal periosteum.f The
pulp and its membrane receive their vascular and nervous fila-
ments from the proper dental vessels and nerves, which run
along the groove in the jaw. The double saccular membrane
receives its vessels and nerves solely from the gums ; and the
only attachment between this and the membrane of the pulp, is
near the base of the latter, where the dental vessels enter it.
The sac is closely united to the gum, hence if we tear away the
gum that covers the jaws, we necessarily bring with it the entire
structure of the germ.

— If at this period, the fourth month, we open the germ, w,e
find the pulp presenting exactly the size and shape of the body
of the teeth first cut, (incisors) and that its membrane has
already commenced the deposit of the bony tip.
— At birth, ossification will be found to have commenced on all
the pulps of the temporary teeth, (the body of the incisors
being nearly completed,) and on each of those of the anterior
permanent grinders. The commencement of ossification is by
three points in the incisors, which form their serrated edges
as seen on their first development, by a single point for the
canine, two for the bicuspide, and three, four, or five on the

* Hunter declared, that the external is soft and spongy, without any vessels;
the other much firmer, " and extremely vascular." Blake on the contrary
asserts, that the external is spongy and full of vessels, the internal one is more
tender and delicate, and seems to contain no vessels capable of containing red
blood.

f This membrane is called by Bell the proper membrane of the pulp, and was
conjectured by Blake, with much probability, to be a "propagation of the peri-
osteum of the jaw." Blake on the Teeth, p. 8. —

112 THE ENAMEL.

large molar, according to the number of processes which they
present. Continuous deposition of the bony matter from the
membrane of the pulp, unites these points together, and by
degrees at different epochs, all the bodies are formed ; the pulp
retiring as it were, as the deposition of bone goes on and
encroaches upon its cavity, and elongates itself downward,
into the shape of the fang. This is finally formed in the same
manner as the bodies, and the» pulp is completely enclosed in
the bony case of the tooth, except at the foramina where the
vessels and nerves enter. Where more than one fang exists to
a tooth, the lower part of the pulp, is previously divided into
an equal number of processes, by little bony partitions which
shoot across from the sides of the alveoli.

Of the Enamel.

— When the development of the bony shell has fairly begun, the
inner layer of the sac becomes thickened and more vascular,
receives a greater amount of blood, becomes closely attached to
the neck, and forms a loose capsule over the body. From the
internal face of this membrane,* is poured out a thickened
whitish granular fluid, called by Mr. Goodin the enamel organ
which Berzelius considers of the nature of lactic acid ; this is
speedily consolidated into a dark chalky substance, deposited
first upon the tips of bone, and gradually extending down in
layers till it covers the whole crown of the teeth. This is the
enamel. It becomes gradually whiter and harder, as though
by a more perfect crystallization, but ^near (o the period at
which the teeth are cut,) it is still so soft, as to be frequently cut
with the gum lancet.

* Blake believed that in man, the enamel was formed solely by the inner
membrane of the sac. The external contributing nothing to the structure of
the teeth. But in graminivorous animals, where the flinty covering of the food
they feed on requires a more perfect grinding apparatus, he thought the external
membrane performed an important part, in adding another element to the struc-
ture of the molar teeth, called by him, crusta petrosa. The cutting teeth are
constructed as those of man. In these animals the enamel of the grinders does
not form a continuous smooth layer as in man, but passes a little way into the
body of the teeth, and is arranged in the form of vertical layers, between which

THE PERMANENT TEETH. 1 13

— Of the three membranes of the germ or follicle, one only
may be considered as permanent, that of the pulp or internal,
which secretes the bone of the tooth.

— The two outer, or those of the sac, cover the crown -of the
tooth ; and as this is pushed forwards by successive depositions
of bony matter from within, they are pressed upon and wasted
away by absorption, like the gum, in direct proportion with
the advancement of the tooth, so that in perfectly natural den-
tition, there is little tension or pressure felt. This is called
cutting the teeth, a name which expresses the fact, sufficiently
well, but literally conveys a wrong idea.

— In cases of difficult dentition, the membranes of the sac re-
tain their density and vascularity, and are probably thickened
by inflammation, and the bony layers formed from the pulp,
resisted in their advancement by these membranes, make
compression upon the pulp and dental nerves ; this, like
continued pressure made in other parts of the body, becomes
exquisitely painful, and gives rise to distressing sympathetic
disturbances. The relief procured by cutting the gums and
sac, will be more or less immediate, according to the degree
of compression and inflammation of the pulp.
— The periosteum covering the fangs of the tooth, is a reflected
continuation of the periosteum lining the socket, and this again
is continuous with that lining the jaw.

Of the Permanent Teeth.

— The adult or permanent teeth, are developed in a manner
almost exactly analogous to the deciduous or infantile. The
germs of many of them are distinctly perceptible in the gums
of the infant at birth. They are placed at first deep in the jaw

after the inner membrane of the sac has been removed by absorption, the outer
one, according to Bell, deposits the pars petrosa, and fills up the intervening
space. This is a substance harder than the bone, but softer than the enamel ;
and the advantage derived from it is, that it is worn oft' by trituration more
readily than the enamel, so that the latter is constantly maintained in sharp
prominent lines upon the surface of the teeth. The same object is here insen-
sibly attained, as a natural consequence of the difference in density of these
parts, which the miller effects with much labor with his pick-hammer, on the
burr-stones of his mill. — P.
10*

114 THE PERMANENT TEETff.

at the inner side of those of the deciduous teeth, to the sac of
which they are attached at top by a neck-like process, as seen
in Fig. 25. As the infantile teeth rise up and make their way

Fig. 25.

through the gum, this process becomes connected with the
gum, and forms what is called by Hunter the gubernaculum^.
dentis, from its influence in giving the permanent teeth their
proper vertical direction, and preventing their making their
way at random through the sides, as they do occasionally in
cases where the gubernaculum has been destroyed.
— Delabarre has given the gubernaculum the name of iter
dentis, from an erroneous belief that it was tubular, like the
duct of a sebaceous follicle, and gradually opened as the tooth
progressed.

— At the fifth month of foetal life, according to Bell, and the
eighth and ninth, according to Blake and Fox, the germs of the
first permanent molars, may be seen at the outside of the in-
fantile row, and those of the permanent incisors behind the
deciduous. Fig. 25 — 1, 2, shows the attachment of the incisor
and molar germs of the two sets, just prior to the eruption of
the first. The permanent germ is at first placed in the socket
of the deciduous tooth, of which it appears, on first view, to
be an offshot or gemmiperous production. Its vessels and
nerves are believed to be mere branches of those of the deci-
duous set. By degrees a distinct socket is formed for it be-
hind the latter, and its process or gubernaculum is elongated,
as seen in Fig. 25 — 3. When the deciduous teeth have cut the
gum, the two sockets are completely distinct, as seen in Fig.
26, and the gubernaculum is attached to the gum.
— Ossification first commences in the permanent set on the
anterior molares, and may be seen at birth ; at the age of

DEVELOPMENT OF THE TEETH. 115

Fig. 26. twelve months, it has progressed to a

considerable extent upon these as well as
upon the incisors and the lower cuspi-
data. At the sixth or seventh year of
age the whole of the permanent teeth are
more or less ossified, and the incisors are
so far completed as to be nearly ready to
make their appearance through the gum.
At this period there are no less than
forty-eight teeth in the two jaws, the twenty deciduous and
the twenty-eight permanent, which are in different degrees of
development. The last molars do not begin to ossify till the
ninth year, and are the last of all to make their appearance
through the gum, whence they have received the name of denies
sapientm or wisdom teeth.

— The permanent teeth, which are more in number and
individually of larger size and form a larger arch than the
temporary, are developed at successive intervals, so as to
correspond exactly, with the increasing size of the jaws from
the infantile to the adult state. Hence they cannot correspond
in position with the deciduous teeth ; the outer permanent
incisor will rise up near the cuspidatus, and the permanent
cuspidatus near the first molar of the deciduous set.
— Exactly in proportion as the bodies of the permanent teeth
are completed and approach the gum, the roots of the decidu-
ous are removed by absorption, till finally the bodies of the
latter only are left fixed mechanically in the gum, and are
tumbled off at the slightest effort. The process of the removal
of the fangs is not perfectly understood ; it is not as was once
supposed produced by the pressure of the subjacent tooth, for
very frequently the commencement of absorption is at the
neck, and not at the root of the tooth, where no pressure can
come, and occasionally takes place even where the germ of the
permanent tooth has been destroyed. It is more probably
owing to the enlarged vessels of the growing permanent teeth,
which come from the same branch with those of the deciduous,
carrying off all its blood by derivation, which leads to the

116 DEVELOPMENT OF THE TEETH.

wasting of the latter set, a process of which we find the analogue
in the development of many parts of the foetus.
— Below is a tabular view of the appearance of the temporary-
teeth, and also of the periods at which they are changed for the
permanent.

— It is to be taken, however, as a general rule liable to
continual exceptions, not only in regard to the time, but also
as to the regular order of appearance. As a general rule, the
teeth of the lower jaw appear first, then the corresponding
teeth of the upper.

Deciduous Teeth.

From 5 to 8 months, the four central incisors,

" 7 " 10 " four lateral incisors,

" 12 " 16 " four anterior rnolares,

"14 " 20 " four cuspidati,

" 18 " 36 " four posterior molares.

Permanent Teeth.

— The first permanent molares usually pierce the gum before
the fall of the central incisors, and their appearance indicates the
approaching change.

— The following are about the medium periods at which they
are cut, but there is a great degree of variation in this respect.
Those of the lower are here indicated, and they most commonly
precede the upper by about two or three months.

About 6| years, the anterior molares,

" 7 " central incisors,

" 8 " lateral incisors,

" 9 " anterior bicuspides,

" 10 " posterior bicuspides,

11 to 12 " cuspidati,

12 " 13 " second molares,

17 " 19 " third molares or denies sapientice.

— Fig. 8 *is a side view of a beautiful s of the permanent
teeth of both jaws, fitted in their socke' showing the exact
manner in which the surfaces of ea^i set are adjusted to each

ABERRATIONS OP DENTITION. 117

other, and the smaller dimensions of the fangs of the wisdom
teeth, owing to the contracted space in which they are
developed. These teeth decay early, are comparatively of
little utility, and probably from the same cause ; for in cases,
where prior to their development one of the molares in front
of them have been removed, they take a more forward
position, are developed with larger fangs, and become much
more serviceable.

— When the first teeth have made their appearance through
the gum, they are not yet completed ; the process of thickening
the body by~ layers from within, and of lengthening the root
below, is for a time still continued by the pulp. After their
completion, the only physiological changes they undergo, is
the wearing down of the bodies by friction, and the filling up
of the top of their cavity within by the pulp, with a yellowish
bony matter in old age, (cementum,) which prevents the
exposure of the cavity, and protects the vasculo-nervous pulp,
which is so exquisitely sensitive, as to be considered by some
in the light of a nervous ganglion. This latter process unhap-
pily is not universal, and is especially defective when the teeth
decay early in life, apparently before the period nature has
assigned them.

*

Aberrations of Dentition.

— Occasionally at birth teeth have been found developed on
the surface of the gum, as in the cases of Louis XIV. of France
and Richard III. of England : in such cases they are generally
mere shells, and are quickly shed, and below exist the double
series of germs, which are developed in the regular order.
— In some rare cases, from the non-existence or disease of the
germs, no teeth have ever been developed.* Borelli mentions
a case of this sort occurring in a woman then seventy-two
years old.

— Sometimes the temporary teeth only exist, which fall at the
regular period and ?s never replaced. Occasionally the set

* Oudet. Consid. sur la Nature des Dents et leur Alterations ; Journal Univ.
Des Sciences Med. torn. 43, 1826.

113 OS HYOIDES.

of permanent teeth have consisted of double or molar teeth all
round. Sometimes the appearance of the temporary teeth has
been protracted to the sixth or seventh year, and even then
followed at regular intervals by the permanent set. The
number of the permanent teeth are sometimes less than usual,
in consequence of the non-development of the wisdom teeth,
which remain locked up in the jaw, and occasionally produce
pain, and even abscesses in the1 bony structure.
— Sometimes there are supernumerary teeth. Haller has seen
in an infant of fourteen years^seventy-two teeth, thirty-six in
each jaw, which appeared to depend upon a greater number
than usual of the dental germs. Some, fond of the marvelous,
have described the eruption of a third set of teeth analogous to
the two first: but according to Hudson and others, this
appearance has probably been owing to the tardy removal of
the deciduous set, and the late supplial of their place by the
permanent teeth.

"—Sometimes the direction of the teeth is vicious, leading into
the ramus of the jaw, or upon the outer or inner surface of the
gums ; or upon the roof of the mouth. Accidental develop-
ments of teeth have likewise been met with in the orbit, the
tongue, pharynx, stomach, and not unfrequently in the ovaries
and uterus. —

Os Hyoides.

The 05 hyoides is a small insulated bone, supported between
the lower jaw and the larynx, by muscles and ligaments,
which proceed from the neighboring parts in various
directions.

The figure of this bone, as its name imports, resembles the
Greek letter v. In its natural situation, the central and convex
part is anterior, and the lateral portions extend backwards.

The central part is called the body, and the lateral portions
the cornua.

The body is broad and its upper edge bent inwards, so that
the external surface is convex, vertically, as well as horizon-
tally. On this surface is a horizontal ridge: the muscles
which proceed from the lower jaw are generally inserted

REGIONS OF THE SKULL. 119

above this ridge, and the muscles from the sternum and

scapula below it.

The internal or posterior surface of the body is very concave.
The cornua, in young subjects, are distinct from the7 body

of the bone, and joined to it by cartilages : near the body of

the os hyoides they are flat ; but their figure soon changes, and

they terminate on each side in a small tubercle.

Fig. .21.* On the upper edge of the bone,

where the cornua unite to the body,
is a process, equal in size to a small
grain of wheat, which has a direction
upwards and backwards ; this is
called the appendix, or lesser cornu
of the os hyoides : from it proceeds

a ligament which is attached to the styloid process of the

temporal bone, and is sometimes ossified.

The basis of the tongue is attached to the os hyoides, and

the motions of the bone have a particular reference to those of

that organ ; but they will be better understood when the parts

with which it is connected have been described.

Regions of the Skull.

— The skull considered as a whole may be divided for the
occasional purpose of defining the seats of injuries into four
regions.

— The superior region or vertex, is bounded anteriorly by the
frontal eminences ; on each side by the temporal ridges and
parietal eminences, and behind by the superior curved line of
the occipital bone and occipital protuberance. The anterior
region or face as seen in Fig. 28, is somewhat oval in contour,
irregular in surface and excavated for the reception of two
principal organs of sense, the eye and the nose. It is formed in
part by the frontal bones and by the bones of the face. It is
bounded above by the frontal protuberances, below by the

* The os hyoides seen from before. 1. The anterior convex side of the body.
2. The great cornu of the left side. 3. The lesser cornu of the same side. The
cornua were ossified to the body of the bone in the specimen from which the
figure was drawn.

120

ORBIT OF THE EYE,

chin, and on the sides by the malar bones. — If a per-
Fig. 28.* pendicular line be drawn down

the face from the inner third of
the supra-orbital ridge to the inner
third of the body of the lower
jaw, it will intersect three fora-
mina, the supra-orbital, infra-
orbital, and mental, each giving
passage to one of the facial
branches of the fifth nerve, the
common seats of facial neu-
ralgia.

The lateral region or side of
the head, comprises the tem-
poral and zygomatic fossae and
the mastoid portion of the tem-
poral bone.

— The inferior region or base of the skull, is very irregular
and presents an internal or cerebral and an external or basilar
surface.

— From the importance of the vessels and nerves which
traverse it, this region requires to be particularly studied. —

An acquaintance with the individual bones which compose the head is princi-
pally useful, as it leads to a perfect understanding of the whole structure, of
which each bone is but a small part.

This structure comprises the cavities which contain the brain and the most
important organs of sense, as well as the foramina subservient to them, which
are of so much importance in the practice of medicine and surgery, and also
in physiology, that the following descriptions are subjoined.

Orbit of the Eye.

The figure of this cavity is that of a quadrangular pyramid
with its angles rounded ; so it resembles a cone, the bottom
being the apex and the orifice the base.

* A front view of the skull. 1. The anterior portion of the frontal bone.
2. The nasal protuberance. 3. The supra-orbital ridge. 4. The optic foramen.
5. The sphenoidal fissure. 6. The spheno-maxillary fissure. 7. The lachrymal
fossa in the lachrymal bones, the commencement of the nasal duct. The figures
4, 5, 6, 7. are within the orbit. 8. The opening of the anterior nares, divided
into two parts bythevomer: the number is placed upon the latter. 9. The
infra-orbital foramen. 10. The malar bone. 11. The symphysis of the lower

ORBIT OF THE EYE. 121

The diameter of the cavity passes obliquely outward from
the apex behind. As the figure is irregular, the side next the
nose does not partake of this general obliquity, but extends in a
straight direction from behind forwards.

The orbit is somewhat contracted at its orifice, and enlarged
immediately within. The form of the orifice is rather oval, as
the transverse diameter is longer than the vertical. Seven bones
are concerned in the formation of this cavity ; the os frontis and
a portion of the lesser wing of the sphenoid bone above, the os
planum of the ethmoid, the os unguis, and the nasal process of
the upper maxillary bone, and the os palati below ; the osmalae,
and orbitar plate of the sphenoid bone, on the outside.

On the upper surface is the depression for the lachrymal
gland ; and at the orifice is the notch or foramen for the supra-
orbitary vessels, See., which have already been mentioned.

On the inner surface are two longitudinal sutures, which
connect the os planum and the os unguis to the os frontis above,
and the os maxillare below. In the upper suture are the two
internal orbitary foramina mentioned in the description of the
os frontis, the anterior of which transmits a fibre of the ophthal-
mic nerve, with an artery and vein ; the posterior transmits only
an artery and vein. There are also two smaller vertical sutures
on each side of the os unguis. On the anterior part of this
inner surface is the ridge of the os unguis, and the grooves for
accommodating the lachrymal sac, which passes into the canal
of the same immediately below.

On the lower surface is the aforesaid canal, formed by the
nasal and orbitar process of the upper maxillary bone, and that
part of the os unguis which is anterior to the ridge. On the
posterior part of this surface is a groove which proceeds for-
wards, and penetrating into the bone, becomes a canal that
terminates in the infra-orbitar foramen ; this groove in the bone is
made a canal by the periosteum. The thin plate which forms this

jaw. 12. The mental foramen. 13. The ramus of the lower jaw. 14. The
parietal bone. 15. The coronal suture. 16. The temporal bone. 17. The squa-
mous suture. 18. The upper part of the great ala of the sphenoid bone. 19.
The commencement of the temporal ridge. 20. The zygoma of the temporal
bone, assisting to form the zygomatic arch. 21. The mastoid process.
11

122 CAVITIES OF THE NOSE.

surface is the partition between the antrum maxillare and the
orbit of the eye, and is more or less absorbed in those cases where
polypi of the antrum maxillare occasion a protrusion of the eye.

The external surface, formed by the malar bone and the
orbitar plate of the sphenoid, is almost flat. In the posterior
part of the orbit it is bounded by two large fissures, which are
now to be described.

In the posterior part of the orbit are three apertures. The optic
foramen, the sphenoidal fissure, and the spheno-maxillary fissure.

The optic foramen opens almost at the bottom of the orbit on
the inside ; its direction is forwards and outwards.

The sphenoidal fissure, formed principally by the lesser and
greater wings of the sphenoidal bone, begins at the bottom of
the orbit, and extends forward, upward, and outward. It is
broad at the commencement, and gradually diminishes to a fissure.
This fissure opens directly into the cavity of the cranium, and
admits the passage of the third, fourth, sixth, and one branch of
the fifth pair of nerves, and an artery, and a vein.

The spheno-maxillary fissure commences also at the bottom
of the orbit, and extends forward, outward, and downward,
between the maxillary bone and the orbitar plate of the sphe-
noid, from the body of the sphenoid to the malar bone. This
fissure opens from the orbit directly into the zygomatic fossa. In
the recent subject it is closed, and only transmits the infra-orbi-
tary nerve and vessels, and a small branch of the superior
maxillary nerve.

The Cavities of the Nose.

These cavities, which are separated from each other by the
septum narium, are contained between the cribriform plate of
the ethmoid and the palatine process of the upper maxillary and
palate bones, and between the anterior and posterior nares.
They are, therefore, of considerable extent in these directions ;
but the distance from the septum to the opposite side of the
nose is so small, that each cavity is very narrow.

The upper surface of each cavity consists of that portion of
the cribriform plate of the ethmoid which is between the septum
and the cellular portions. Anterior to this, each cavity is

CAVITIES OF THE NOSE. 123

bounded by the internal surface of the os nan of its respective
side ; and posterior to it, by the anterior surface of the body of
the sphenoid bone. These anterior and posterior surfaces form
obtuse angles with the upper surface of the nose, and^are im-
mediately above the openings called anterior and posterior nares.
The anterior surface partakes of the figure of the os nasi ; the
upper surface has the perforations of the cribriform plate ; the
posterior surface has an opening, equal in diameter to a small
quill, that leads into the sphenoid cell, and is also broader than
the anterior or superior surface.

The internal surface, formed by the septum of the nose,
which is composed of the vomer, the nasal plate of the ethmoid,
and the cartilaginous plate, is flat, but rather inclined to one side or
the other, so as to make a difference in the size of the nasal cavities.
Fig. 29.* The external surface is very

irregular; it is formed by the
cellular portions of the ethmoid;
by a small portion of the os
unguis ; by the upper maxillary
bone ; the os turbinatum infe-
rius ; the os palati ; and the
internal pterygoid process of
the 05 sphenoides. The upper
part of this surface is formed
by the internal surface of the
cellular portions of the ethmoid,

* Fig. 29. A longitudinal section of the nasal fossa (taken from Wilson) —
made to the right side of the vomer, and the bony septum removed in order to
exhibit the external wall of the left nasal fossa. 1. Os frontis — 2. Os nasi. 3.
The cristagalli process of the ethmoid. The groove between fig. 1 &c 3, is the
lateral boundary of the foramen caecum. 4. The cribriform plate of the ethmoid.
5. Part of the sphenoidal cells. 6. The basilar portion of the sphenoid bone.
Bones 2, 4, & 5. form the superior boundary of the nasal fossa. 7, 7. The
articulating surface of the palatine process of the superior maxillary bone.
The groove between 7, 7. is the lateral half of the incisive canal, and the dark
aperture in the groove the inferior termination of the left naso palatine canal.
8. The nasal spine. 9. The palatine process of the palate bone. a. The superior
turbinated bone marked by grooves and apertures for filaments of the olfactory
nerve, b. The superior meatus. c. A probe passed into the posterior ethmoidal
cells, d. The opening of the sphenoidal cells into the superior meatus. e. The
•spheno-palatine foramen. /. The middle turbinated bone, g, g. The middle
meatus. h. A probe passed into the infundibular canal, leading from the frontal

124 CAVITIES OF THE NOSE.

which have been described at page 76. It extends from the sphe-
noid bone, very near to theossanasi ; and is uniformly flat and rough.

About the middle of it begins a deep groove, which penetrates
into the cellular structure of the ethmoides, and passes obliquely
downwards and backwards. At the upper end of this groove is
the foramen by which the posterior ethmoidal cells communicate
with the nasal cavity.

This is the upper channel &r meatus of the nose. At the
posterior end of it is a large foramen formed by the nasal plate
of the os palati and the pterygoid process of the os sphenoides,
and therefore called pterygo or spheno-palatine foramen. It
opens externally, and transmits a nerve and an artery to the nose.

Below the meatus is the upper spongy bone, which presents a
convex surface ; its lower edge is rolled up and not connected
with the parts about it. This spongy bone covers a foramen in
the ethmoid bone, by wbich its anterior cells and the frontal
sinuses communicate with the nose.

Below this spongy bone is the middle channel, or meatus of
'the nose. The channel extends from the anterior to the poste-
rior part of the cavity. It is very deep, as it penetrates to the
maxillary bone. The cells of the ethmoid are above it; the
inferior turbinated bone below it ; and the upper spongy bone
projects over it. In this channel is the opening of the great
cavity of the upper maxillary bone. At the anterior extremity
of it is a small portion of the os unguis, which intervenes between
the nasal process of the upper maxillary bone and the cells of
ihe ethmoid, and continues down to the lower spongy bone.

The lower spongy bone is nearly horizontal, and very conspi-

sinuses and anterior ethmoid cells ; the triangular aperture immediately above
the letter is the opening of the maxillary sinus, i. The inferior turbinated bone.
Jc, k. The inferior meatus. I, L A probe passing up the nasal duct, showing the
direction of that canal. The anterior letters g, /;, are placed on the superio?
maxillary bone, the posterior on the palate bone. m. The internal pterygoid
plate, n. The hamular process. 0. The external pterygoid plate, p. The situa-
tion of the opening of the Eustachian tube. q. The posterior palatine foramina,
the letter is placed on the hard palate, r. The roof of the left orbit. 5. The
optic foramen, t. The groove for the last turn of the internal carotid artery
converted into a foramen by the development of an osseus communication be-
tween the anterior and middle clinoid processes, v. The sella turcica. z. The
posterior clinoid process. —

THE CAVITY OF THE CRANIUM. 125

cuous. It extends almost from one opening of the nose to the
other. Under this bone is the third and largest channel or infe-
rior meatus of the nose. It is made large by an excavation of
the upper maxillary bone, particularly at the anterior part. It
affords a direct and very easy passage to the posterior opening of
the nose and the throat.

Near the anterior extremity of this meatus is the lower orifice
of the lachrymal duct, which is so situated that a probe properly
curved can be readily passed into it through the nostril.

There are, then, four foramina on each side, which form com-
munications between the cavities of the nose and the adjacent
cells, viz.

One in the upper meatus, which leads to the posterior ethmoid
cells.

A second in the middle meatus, which leads to the anterior
ethmoid cells and the frontal sinuses.

A third in the same meatus, which opens into the maxillary
sinus.

A fourth in the anterior surface of the body of the sphenoidal
bone, which opens into the sphenoidal sinus.

To these must be added the opening of the lachrymal canal.

It will be moat useful to the student of anatomy, after placing three or four of
the uppermost cervical vertebrae in their natural situation, to take a view of

The Cavity between the spine and the posterior Nares, which
is bounded above, by the cuneiform process, passing obliquely
upward and forward ; laterally, by soft parts not yet described ;
behind, by the bodies of the cervical vertebrae ; and before, by
the posterior nares, each of which is oblong in form, rounded
above, flat below, and separated from the other by a thin parti-
tion, the vomer.

The Cavity of the Cranium.

The upper concave surface of this cavity corresponds with
the figure of the cranium. The ridge in it for supporting the fal-
ciform process of the dura mater, the groove made by the longi-
tudinal sinus, the impressions of the arteries, and the pits made
by the convolutions of the brain, are particularly to be noticed.
11*

126

THE INTERNAL BASIS OF THE CRANIUM.

The Internal Basis of the Cranium

Is much more important. It is divided into three fossae on each
side ; the anterior of these are most superficial, and the posterior
the deepest. The bottoms of the anterior foss& are formed by
the orbitar processes of the osfrontis, and consequently are con-
vex ; between them is the cribriform plate of the ethmoid, which
is commonly sunk below the adjoining surface. The crista galli
is very conspicuous ; and the foramen caecum can almost always
be seen. The crista galli is evidently the beginning of the pro-
minent ridge, which continues on the os frontis, and supports the
falx of the dura rnater. The posterior margins of these fossae
are formed by the lesser wings of the sphenoid bone.

The middle fossa are formed by the great wings of the
sphenoidal bone, and by the squamous and petrous portions
of the temporal bone. They are lower than the anterior,
and higher than the posterior fossae. The projection of the
Fig. 30.* margin of the anterior fossae

into these cavities, corresponds
with the separation between
the anterior and middle lobes
of the brain. The suture be-
tween the sphenoidal and tem-
poral bones is evident in these
fossae. The upper surface of
the body of the sphenoid bone,
or the sella turcica is between
them ; and all the peculiarities
of its surface are very conspi-
cuous. The first five foramina
of the sphenoidal bone can IK-
easily ascertained, and also, the
anterior foramen lacerurn and

* The cerebral surface of the base of the skull. 1. One side of the anterior
fossa j the number is placed on the roof of the orbit, formed by the orbital plate
of the frontal bone. 2. The lesser wing of the sphenoid. 3. The crista galli.
4. The foramen caecum. 5. The cribriform lamella of the ethmoid. 6. The
processus olivaris. 7. The foramen opticum. 8. The anterior clinoid process.
9. The carotid groove upon the side of the sella Turcica, for the internal carotid
artery and cavernous sinus. 10, 11, 12. The middle fossa of the base of the
skull. 10. Marks the great ala of the sphenoid. 11. The squamous portion of

THE INTERNAL BASIS OF THE CRANIUM. 127

termination of the foramen caroticum, with the impressions
made by the carotid arteries on the sides of the sella turcica.
The petrous portions of the temporal bones are the posterior
boundaries of the middle fossae. Their oblique direction,
inwards and forwards, is particularly remarkable; being formed
like triangular pyramids. Two of their sides are in the cavity
of the cranium ; one, which is anterior, forms a portion of the
middle fossa ; and the other forms a part of the posterior fossa.
The edge between them is very prominent, and has the tento-
rium or horizontal process of the dura mater attached to it. On
the anterior surface, in the middle fossa, may be traced the
groove, and the foramen for the Vidian nerve.

The posterior fossae are larger as well as deeper than the
other two. Their boundaries are well defined by the edges of
the petrous bones above mentioned, and by the grooves of the
horizontal parts of the lateral sinuses. These fossae are nearly
separated from the general cavity by the tentorium, which is
attached to the edge of the petrous bone and also to the edge
of the horizontal part of the groove for the lateral sinuses. On
the tentorium lie the posterior lobes of the cerebrum ; and under
it, in these fossae, is the cerebellum.

These fossae may be considered as one great cavity, which is
circular behind, and somewhat angular before. The angular
surfaces are formed by the posterior sides of the petrous portions.
Between them, is the oblique surface of the cuneiform process of
the occipital bone, which descend to the great foramen. On the
surface of each petrous bone is the meatus auditorius internus,
and the orifice of the aqueduct of the vestibule. Behind the
petrous" portion, the groove for the lateral sinus is very conspicu-
ous ; it terminates in the posterior foramen lacerum, which is
evidently formed by the temporal and the occipital bones. At

the temporal bone. 12. The petrous portion of the temporal. 13. The sella
Turcica. 14. The basilar portion of the sphenoid bone, surmounted by the pos-
terior clinoid processes. 15. The foramen rotundum. 16. 'the foramen ovale.
17. The foramen spinosum ; the small irregular opening between 17 and 12 is
the hiatus Fallopii. 18. The posterior fossa of the base of the skull. 19, 19.
The groove for the lateral sinus. 20. The ridge upon the occipital bone, which
gives attachment to the falx cerebelli. 21. The foramen magnum. 22. The
meatus auditorius internus, 23. The jugular foramen.

128

EXTERNAL BASIS OF THE SKULL.

the anterior part of this foramen is most commonly a small bony
process, which separates the eighth pair of nerves from the
internal jugular vein, as they pass out here.

The anterior condyloid foramen for the passage of the ninth
pair of nerves, appears in the surface of the great occipital hole,
immediately below the foramen lacerum. From the back part
of this hole the spine, which forms the lower limb of the cross,
passes up; and on each side of it are the great depressions
which accommodate the two lobes of the cerebellum.

External Basis of the Skull.

t

The external surface of the base of the skull is very irre-
gular. When the head is inverted, we see the external protu-
berances of the as occipitis, formerly described. The mastoid
processes of the ossa temporum are on the same transverse
line with the great foramen of the os occipitis ; but the foramen
being larger extends farther forward. On the inside of the
mastoid process, the fissure for the digastric muscle is very con-
spicuous, and also the suture between the mastoid process and
the occipital bone.

Fig. 31.* The oblique direction of

the occipital condyles and
the slanting position of
their articulating surfaces
are particularly striking.
The posterior condyloid
foramina for the cervical
veins, and the anterior for
the ninth pair of nerves,
are also in view. The
position of the cuneiform
process of the os occipitis
is by no means horizontal,
but extends forwards and
upwards. The petrous or
pyramidal portion of the
temporal bone commence?

* The external or basilar surface of the base of the skull. 1,1. The hard
palate. The figures are placed upon the palate processes of the superior maxil-

BASIS OF THE SKULL. 129

between the mastoid process and the condyle of the lower jaw,
and extends obliquely forwards and inwards, having the
occipital bone behind it, and the glenoid cavity or fossae and
the os sphenoides before it. At the commencement, the
surface of the petrous portion is not horizontal, but oblique,
sloping into the glenoid cavity with a sharp edge downwards.
This edge in some cases is curved so as to surround the basis
of the styloid process, which arises in contact with it, and
projects downwards, on each side of the vertebrae. Between
the mastoid and styloid process, is the foramen stylo-mastoi-
deum. On the inside of the styloid process, and rather anterior
to it, is the foramen lacerum posterius, for the internal jugular
vein, the eighth pair of nerves, &tc. This foramen passes
obliquely backwards and upwards, and is bounded behind by
the jugular process of the os occipitis, which bone seems to
contribute most to its formation. Very near to this hole on the
inside is the anterior condyloid foramen ; and rather anterior to
it is the opening of the carotid canal, which forms a curve in the
bone as it passes upwards, inwards, and forwards.

From the foramen lacerum posterius, the suture between
the cuneiform process of the occipital and the petrous portion
of the temporal bone, extends to the foramen lacerum anterius
of the base of the cranium ; which is closed by cartilage in
the recent subject, but is of an irregular and rather triangular
form in the macerated head ; this hole is formed by the
occipital, sphenoidal, and petrous bones. The suture or
connexion between the petrous bone and the os sphenoides, is

lary bones. 2. The incisive, or anterior palatine foramen. 3. The palate pro-
cess of the palate hone. The large opening near the figure is the posterior
palatine foramen. 4. The palate spine ; the curved line upon which the num-
ber rests, is the transverse ridge. 5. The vomer dividing the openings of the
posterior nares. 6. The internal pterygoid process. 7. The scaphoid fossa. 8.
The external pterygoid plate. The interval between 6 and 8 (left side of the
figure), is the pterygoid process. 9. The zygomatic fossa. 10. The basilar
process of the occipital bone. 11. The foramen magnum. 12. The foramen
ovale. 13. The foramen spinale. 14. the glenoid fossa. 15. The meatus audi-
torius externus. 16. The foramen lacerum basis cranii. 17. The carotid fora-
men of the left side. 18. The foramen lacerum posterius, or jugular foramen.
19. The styloid process. 20. The stylo-mastoid foramen. 21. The mastoid
process. 22. One of the condyles of the occipital bone. 23. The posterior
condyloid foramen.

130 BASIS OF THE SKULL.

continued on the anterior side of the petrous bone, from the
fissure of the glenoid cavity to the anterior foramen lacerum.
The styloid process of the os sphenoides, which is seldom more
than four lines in length, appears at the edge of this suture.
On the inside of the glenoid cavity, and on the inside of this
process, in the suture formed between the petrous and sphenoid
bones, is the bony orifice of the Eustachian tube.

The foramen spinale, for" the middle artery of the dura
mater, is at a very small distance from the Eustachian tube,
immediately anterior to it ; and at a small distance on the
inside and front of this foramen is the foramen ovale, for the
inferior maxillary nerve, or the third branch of the fifth pair.
— Proceeding from before backwards the base of the skull apper-
taining to the face is seen to be formed by the palate processes
of the superior maxillary and palate bones ; by the vomer ; the
pterygoid spinous processes, and part of the body of the sphenoid.
— The roof of the mouth as seen at 1, 3, Fig. 31, is constituted
by the palatine processes of the superior maxillary and palate
bones. The transverse suture which separates them is well
seen on the left side of the cut. In the longitudinal suture
and directly behind the front incisor teeth, 2, is the incisive or
anterior palatine foramen, the inferior opening of the naso-
palatine canal, which lodges the ganglion of Cloquet (naso-
palatine) and transmits the anterior palatine nerves. The
posterior palatine foramina, are placed near the posterior angles
of the hard palate, for the purpose of transmitting to the palate
the blood-vessels and nerves of that name. The opening of
the larger foramen is seen near 3, Fig. 31. On the innetf side of
this foramen is seen the transverse ridge upon which is inserted
the expanded tendon of the tensor palati muscle. The
rounded crescentic border, which terminates posteriorly each
half of the hard palate, gives attachment to the velum pendu-
lum palati ; and in the middle line 4, is seen the palate spine
from which is hung the azygos uvuloe muscle. The posterior
nares is seen immediately above divided by the vorner, 5, and
bounded externally by the internal pterygoid processes, 6. By
the side of the shelving base of the vomer and partly formed
by it are the pterygo-palatine canals, which transmit the

SIDE OF THE HEAD. 131

ptery go-palatine arteries. The external pterygoid process is
seen at 8, and between the two processes, is the pterygoid
fossa, which is occupied by the internal pterygoid muscle.
On the outer side of the external pterygoid process i^ the
zygomatic fossa. The internal pterygoid process is long and
narrow, having at its apex the hamulus, and at its base the
scaphoid fossa from which arises the circumflexus or tensor
palati muscle. —

Side of the Head.

Those portions of the side of the head which are formed by
the frontal, parietal and occipital bones, and by the squamous
part of the temporal, require no explanation here ; but the
region which is behind the malar and upper maxillary bone,
and within the zygomatic processes of the temporal and malar
bones, which comprises part of the temporal and zygomatic
fossae of some anatomists, is both important and obscure.

To obtain a view of this, the lower jaw should be removed,
and the zygoma sawed away, in one preparation ; and in
another, the upper maxillary and palate bones of one side
should be applied in their natural position, to the os sphenoides,
without any of the other bones.

The upper part of this region, formed by the sphenoidal,
frontal and malar bones, is made concave by the form of the
external angular part of the os frontis and of the os malse ;
which projects backwards so as to cover a large portion of it.

The lower part is formed principally by the external surface
of the pterygoid process of the sphenoid bone, and by the
posterior surface of the upper maxillary. Between the lower
end of the pterygoid process and the upper maxillary bone, a
small portion of the os palati intervenes ; but in many adult
subjects it is not to be distinguished from the other bones. At
this place, the pterygoid process and these bones appear to be
in close contact ; but as they pass upwards they recede from
each other so as to form a considerable aperture, which
continues the whole length of the pterygoid process. This
fissure, which may be called pterygo-palatine or pterygo-
maxillary, would open into the posterior part of the cavity of

132 THE FORM OF THE CRANIUM.

the nose, if the nasal plate of the os palati did not intervene ;
this plate forms a partition, which separates the nose from this
fissure : and the spheno-palatine foramen, formed principally
by it, transmits a nerve and blood-vessels to the nose.

The fissure is vertical : at the back of the orbit, it unites
with the spheno-maxillary fissure of the orbit, which is almost
horizontal, and at the place of their junction, the sphenoidal, or
upper fissure of the orbit, opeffs also.

The foramen rotundum, which transmits the second branch
of the fifth pair, or the upper maxillary nerve, is likewise
situated near this place ; and when the upper maxillary, the
sphenoidal, and the palate bones are in their natural situation,
the distribution of the branches of this important nerve can be
easily understood : for the same view presents the course of its
various branches ; viz. to the nose, by the spheno-palatine fora-
men ; to the cavity of the cranium, by the pterygoid foramen ;
to the orbit, and the inferior obitary canal, by the spheno-max-
illary fissure ; and to the roof of the mouth, by the palato-max-
illary canal.

The Form of the Cranium.

The form of the cranium is that of an irregular oval. The
greatest length of its cavity is between a part of the os frontis
above the crista galli, and of the os occipitis above the centre
of the crucial ridge.

The greatest breadth is at about two-thirds of the distance
from the first to the last of these positions. This tranverse
diameter touches the sides of the cranium near the posterior
part of the basis of the petrous portion of the temporal bone.
The difference between these longitudinal and transverse
diameters varies greatly in different persons, as their craniums
approach to the oval or round figures.

The greatest depth of the cavity is between the posterior
part of the cuneiform process of the occipital bone, and a part
of the cranium which is nearly over it about the middle of the
sagittal suture.

The figure of the cranium is somewhat varied in different

THE FORM OF THE CRANIUM. 133

races of men ; and it has been much changed by the particular
management of several savage nations.

In North America, the Choctaw tribe of Indians were for-
merly accustomed tox make their foreheads perfectly flat, and
sloping obliquely backwards. They have latterly disused this
practice ; but one of their nation, whose head had this form, was
in Philadelphia about the year 1796.

At this time a tribe who inhabit a district of country near the
sources of the Missouri river, are in the practice of flattening
both the frontal and occipital regions of the head ; so that a
small part only, of the middle of it, remains of the natural form,
between these flattened sloping surfaces. J^

In the case of the Choctaw man above-mentioned, it did not
appear that his health, or his intellectual ^operations, were any
way affected by this form of his head.

During infancy, the cranium sometimes increases to a preter-
natural size, as disproportionate to the face as if it were
affected by hydrocephalus. In many of these instances, that
disease ultimately shows itself; but in other cases, the preter-
natural increase of the cranium finally stops without the occur-
rence of disease ; and the disproportion is lessened by the
increase of the face in the ordinary progress of growth.

In many cases where men have deviated from the ordinary
stature, the head has preserved the common size. It is therefore
said to be small in giants, and large in dwarfs.

— Many efforts have been made to determine rigorously the
dimensions of the cavity of the cranium. This may be done
with considerable accuracy from the exterior of the skull, by
making allowances for the various degrees of development in
which the frontal sinuses are found in different individuals.
The thickness of the diploe seldom varies in different skulls
more than one or two lines in thickness. I have, however,
several negro skulls in my possession the walls of which are
nearly three-quarters of an inch in thickness, and so com-
pact in their composition as to present very little of the
diploic or cellular structure. When measured from the
interior, a skull of ordinary capacity will be found in its

•'" '• '•; :</*rr*^'/ ^
~ *- '•

134 FACIAL AND OCCIPITAL ANGLES.

longitudinal diameter, (between the frontal spine and longitudi-
nal sulcus,) five inches and a half; in its transverse, (between
the bases of the petrous portions of the temporal bones,) four
and a half; between the parietal fossae five inches, and between
the lesser wings of the sphenoid bones, three inches and three-
quarters ; in the vertical, from the foramen magnum to the sagit-
tal suture, four inches and a half.

— Several plans have also bean adopted, by the cranioscopists,
to determine the relative development of the cranium (which
is filled with the brain) and that of the face. The best known
of these are those of Camper, Daubenton and Cuvier. The
facial angle of Camper, is taken by extending a horizontal line
from the external auditory meatus, on a line with the floor of
the nostril, so as to follow nearly in the direction of the base
of the cranium, and by dropping upon this a second from the
most prominent part of the forehead to the extremity of the
upper jaw. The area between them is the facial angle, and
will be the more acute, in direct proportion as the face is devel-
oped in front, and the forehead is sloped backwards. This
angle is of course larger in man than in any other animal, and
varies in size in the different races of men. In a well formed
white or Caucasian, it is usually about 80°; in the Mongolian
about 75° ; in Negroes about 70° ; in the different species of
monkeys it varies from 65° to 30°. As a test of the intellectual
capacity of individuals, it is but little to be relied on.
—The occipital angle of Daubenton, is formed by drawing two
lines, one from the inferior border of the orbit, to the anterior
margin of the occipital foramen, the other drawn from the
anterior to the posterior border of the occipital foramen, and
extended forwards. The angle between the two, is the occipital.
As the direction of the occipital foramen depends upon the
manner in which the head is articulated with the vertebral
column, it will be the larger, the less favorably the animal is
constructed for the upright posture. In a well-formed Caucasian
skull, it is about 3°. In the ox it is about 70°. Daubenton
has thus done for the posterior part of the head what Camper
has done for the anterior.

HEAD OF THE FffiTUS. 135

— Cuvier's method consists in dividing the skull vertically, and
establishing a comparison between the area of the cranium and
that of the face. In a well-formed Caucasian he finds the area
of the cranium, quadruple that of the face. In the Mongolian
variety, he found the area of the face had increased over this
proportion one-tenth, in the Negro, one-fifth ; in monkeys, one-
half. Tiedemann has adopted a plan of measuring the capacities
of different crania, by filling them with seeds from the occipital
foramen, and subsequently measuring their contents. This
method as well as some others, has been employed for the same
purpose by Prof. S. G. Morton of this city, in the preparation of
his elegant and interesting work on Crania Americana, and the
results have been so carefully detailed by him, as to leave hence-
forth little to be wished upon a subject which has excited much
attention among physiologists. The whole capacity of the
cranium is found on an average, greater in the Caucasian variety
of the human race, than in any other.

The Head of the Foetus.

In the foetus, those bones, which form the vault of the cra-
nium, originally consist of one plate only ; which is compose^
of radiant fibres.

At birth, the os frontis consists of two pieces, which join each
other in the middle of the forehead.

The parietal bones are each in a single piece ; but they are
incomplete at their edges and their angles.

The temporal bones have no appearance of mastoid or styloid
processes. Instead of a meatus auditorius externus, there is a
bony ring in which the membrana tympani is fixed. The
squamous and petrous portions, and this ring, are originally
formed separate ; but at the period of birth they often adhere to
each other.

The os occipitis is composed of four pieces : the first and
largest, extends from the beginning or angle of the lambdoidal
suture to the upper edge of the great occipital foramen. Each
side of the foramen, and the condyle on it, is formed by a
distinct piece. The front part is formed by the cuneiforrc

136 HEAD OF THE FOETUS.

process, which is separate from the other parts and forms the
fourth piece.

The sphenoidal bone may be separated by maceration into
three pieces. The body and the little wings form one piece.
Each of the great wings, with the pterygoid processes united
to it, forms also a piece. The body of the bone is entirely
solid.

A large part of the ethmoid9 is in a cartilaginous state. It is
divided into two portions by a partition of cartilage, which
occupies the place of the nasal plate and the crista galli.

In consequence of the imperfect formation of the bones which
compose the vault of the cranium, there are several deficiencies
in it. Thus the superior anterior angles of the parietal bones
being incomplete, and also the upper angles of the pieces which
compose the os frontis, a vacuity with four sides is occasioned,
which is termed the

Anterior fontanel. This opening may be distinguished by its
form, as well as its greater size, from another vacuity which is
produced in a similar way at the other end of the sagittal suture,
and called the

Posterior fontanel: but as there are only three bones con-
ce*rned in its formation, viz. the two parietal and the occipital,
this vacuity is triangular.

Besides these, there are two other vacuities or fontanels on
each side, at the two lower corners of each parietal bone : these,
however, are much less than those first described.

The smaller fontanels do not continue open long ; but the
anterior fontanel is seldom completely closed before the end of
the third year.

It is very obvious upon an examination of the cranium, that
the centre of the base is better calculated to resist pressure than
any other part; as the cuneiform process of the occipital bone,
the petrous portion of the temporal, and the body of the sphe-
noidal bone, which compose a large part of it, are very firm and
substantial.

The face of the fcetus differs very essentially from that of the
adult. Although the orbits of the eyes are very large when

THE SPINE. 137

compared with the size of the head, that portion of the face
which is below them is very small, and has little depth.

The upper maxillary bones have no sinuses in them ; and their
orbitar plates are not much elevated above the cavities for con-
taining the posterior teeth ; in consequence, the depth of the
face is very small, and its whole aspect is affected.

The nose of the fwtus differs greatly from that of the adult
in respect to its sinuses ; for not only are the maxillary cavities
wanting, but those of the frontal and sphenoidal bones also.

The lower jaw is formed in two pieces, which unite at the
middle ; and hence the term symphysis is used in describing
the chin. The bone is not only less broad in proportion than
that of the adult, but the Angles are more obtuse, and the pro-
cesses which arise from them are more sloping.

The head of the foetus is much larger in proportion to the
body than that of the adult.

Of the Trunk.
The Trunk consists of the SPINE, THORAX, and PELVIS.

The Spine.

The spine is the long pile of bones extending from the
condyles of the occiput to the end of the os coccygis. It some-
what resembles two unequal pyramids joined in a common base.
It is not, however, straight; for its upper part being drawn
backwards by strong muscles, it gradually advances forwards
to support the oesophagus, vessels of the head,.&c. Then
it turns backwards, to make room for the heart and lungs.
It is next bent forwards to support the viscera of the abdomen.
It afterwards turns backwards for the enlargement of the pelvis. (
And, lastly, it is reflected forwards, for sustaining the lowest '
great intestines.

The spine is commonly divided into true and false vertebra ;
the former constituting the long upper pyramid, which has its
base below ; while the false vertebrae make the shorter lower
pyramid, whose base is above.

138

Fig. 32.

THE VERTEBRAE.

True Vertebra.

The true vertebra are the twenty-four
upper bones of the spine, on which the seve-
ral motions of the trunk of our bodies are per-
formed. Their name is derived from the
Latin verb verier e.

Each of these vertebrae is composed of its
body and processes.

The body is the thick spongy forepart,
which is convex before, concave backwards,
horizontal and flat in most of them above and
below. Numerous small holes, especially
on the fore and back part of their surface,
giving passage to their vessels, and allow the
ligaments to enter their substance. The edges
of the body of each vertebra? are covered,
especially at the forepart, with a ring of bone
firmer and more solid than the substance of
the body any where else. These rings seem
to be joined to the vertebrae in the form of
epiphysis. They are of great use in pre-
venting the spongy bodies from being broken
in the motions of the trunk.

Between the bodies of each two adjoining
vertebrae, a substance between the nature of
ligament and cartilage is interposed ; which
seems to consist of concentrical curved fibres,
when it is cut horizontally ; but when it is
divided perpendicularly, the fibres appear

* The vertebral column — consisting of twenty-four
true vertebrae ; and two false, the sacrum and os coccygisj
each made up by the consolidation of four bones which
are separate in the young subject. — It extends the
whole length of the trunk. — It may be divided into four
regions — the cervical comprising the seven vertebrae from a to b. — The dorsal, the
twelve vertebrae from b to c. — The lumbar, the five vertebrae from c to d. — The
pelvic, or sacro-coccygeal portion comprising the false vertebrae, the sacrum and
coccyx from d to /. — From e to /. are the four small bones forming the os
coccygis.

THE VERTEBRJE. 139

oblique and decussating. The outer part of these intervertebral
ligaments is the most solid and hard; and they gradually
become softer till they are almost in the form of a glairy liquor
in the centre. The external fibrous part of each is capafcle of
being greatly extended, and of being compressed into a smaller
space, while the middle fluid part is incompressible, or nearly
so. The middle point is therefore a fulcrum or pivot, on which
the motion of a ball and socket may be made, with such a
gradual yielding of the substance of the ligament, in whatever
direction our spines are moved, as saves the body from violent
shocks, and their dangerous consequences. This ligamento-
cartilaginous substance is firmly fixed to the horizontal surfaces
of the bodies of the vertebrae, to Connect them ; in which it is
assisted by a strong membranous ligament, which lines all their
concave surface, and by a still stronger ligament that covers all
their anterior convex surface.

The elastic substance seems to be in a state of compression
by the exterior ligament and the bones ; for, if a section be
made through a portion of the vertebrae and the intervertebral
substance, this substance will expand, so that its surface will
be much higher than that of the vertebrae, h is s_o elastic, and
so much confined, in some subjects, that a sharp knife, if plunged
into it will be gradually ejected when the hand is with-
drawn.

The bodies of the vertebrae are, with some exceptions,
smaller and more solid above, but more spongy as they descend.
The cartilages between them are thick, and the surrounding
ligaments are strong in proportion to the size of the vertebrae.
By this disposition, the greatest weight is supported on the
broadest, best secured base, and the middle of the body is
allowed a large and secure motion.

From each side of the body of each vertebrae, a bony bridge
or pedicle is produced backwards, and to one side ; from the
posterior end of which one slanting process rises, and another
descends. The smooth, and generally the flattest side of each
of these four processes is covered with a smooth cartilage ; and
the two lower processes of each upper vertebrae are fitted to

140 THE VERTEBRA.

and articulated with the -two upper processes of the vertebrae
below, having their articular ligaments fixed into the rough line
round their edges. These processes are termed the oblique
or articulating. •*"

From between the oblique processes of each side, another pro-
cess extends laterally, which is called the transverse.

From the back part of the roots of the two oblique processes,
and of the transverse process of* each side, a broad oblique bony
plate called the lamella is extended backwards : where these
meet, the seventh process of the vertebra takes its rise, and
stands out backwards. This being generally sharp-pointed and
narrow-edged, it has therefore been called spinous process ;
from which this whole chain of bones has got its name.

Besides the common ligament which lines all the internal sur-
face of the spinous processes as well as of the bodies, particular
ligaments connect the bony bridges and processes of the contig-
uous vertebrae together.

The substance of the processes is considerably stronger and
firmer, and has a thicker external plate than the bodies of the
vertebrae themselves.

The seven processes form a concavity at their forepart, which,
joined to the one at the back part of the bodies, make a great
hole ; and when the vertebra are placed upon each other in
their natural order, these holes form a long tube for containing
the spinal marrow.

In the upper and lower edge of each lateral bridge or pedicle,
there is a notch. These are so adapted to each other in the
contiguous vertebras, as to form a round hole in each side, be-
tween each two vertebrae, through which the nerves proceed
from the spinal marrow, and its blood-vessels pass.

The articulations of each two vertebrae are consequently
double ; for their bodies are joined by the intervening cartilage
above described ; and their oblique processes, being tipped
with cartilages, are connected together by ligaments so as to al-
low a small degree of motion on every side. Hence, it is evident
that their centre of motion is altered in different positions of

CERVICAL VERTEBRJE. 141

the trunk : for, when we bow forwards, the weight bears
entirely on the bodies of the vertebrae ; if we bend back, the
oblique processes support it ; if we recline to one side, we rest
upon the oblique processes of that side and part of the boclies ;
if we stand erect all the bodies and oblique processes have their
share in our support.

The true vertebrce are divided into three classes, which agree
with each other in their general structure, but are distinguished
by several peculiarities.

These classes are named Cervical, Dorsal, and Lumbar.
The CERVICAL are the seven uppermost vertebrae ; which
are distinguished from the rest by these marks : their bodies
are smaller and more solid than any others ; and are flattened on
the front surface. They are also flat behind, where small
processes rise, to which the internal ligaments are fixed. The
upper surface of the body of each vertebras is made hollow,
by a slanting thin process which is raised on each side. The
lower surface is also hollowed, but in a different manner; for
here the posterior edge is raised a little, and the anterior one
is considerably extended. Hence, the cartilages between these
vertebrae are firmly connected, and their articulations are
secure.

Fig. 33.* These cartilages are thick, especially

at their forepart; which is one rea-
son why the vertebrae project for-
ward as they descend, and have the
larger motion.

Their oblique processes more justly
deserve that name than those of any
other vertebrae. They are situated
slanting ; the upper ones having their
smooth and almost flat surfaces facing obliquely backwards

* A central cervical vertebra, seen upon its upper surface. 1. The body
concave in its middle, and rising on each side into a slanting thin process or
ridge. 2. The lamina or lamella. 3. The pedicle rendered concave by the
superior intervertebral notch. 4. The bifid spinous process. 5. The bifid or
notched transverse process. 6. The vertebral foramen. 7. The superior oblique
or articular process. 8. The inferior oblique or articular process.

142 CERVICAL VERTEBRAE.

and upwards ; while the inferior oblique processes have these
surfaces facing obliquely forwards and downwards.

The transverse processes of these vertebrae are formed in a
different manner from those of any other bones of the spine ;
for, besides the common transverse process rising from between
the oblique processes of each side, there is a second one that
comes out from the side of the body of each vertebras ; and
these two processes, after leavmg a circular hole for the passage
of the vertebral artery and vein, unite and form a groove on
their upper surface to protect the nerves that pass in it. They
terminate obtusely on each side, for the insertion of the
muscles.

The spinous processes project backwards almost horizontally.
They are shorter than those of any other vertebrae, and are
forked or double at their ends ; they therefore allow a more con-
venient insertion to muscles.

The thick cartilages between the bodies of these cervical
vertebrae, the obliquity of their oblique processes, and the
shortness and horizontal situation of their spinous processes, all
conspire to allow them large motion.

The holes between the bony cross bridges, for the passage
of the nerves from the spinal marrow, have their largest share
formed in the lowest of the two vertebrae, to which they are
common.

So far most of the cervical vertebrae agree ; but they have
some particular differences, which require a separate conside-
ration.

The first, from its use in supporting the head, has the name
of atlas. \ Contrary to all the other vertebrae of the spine, it
has no body ; but, instead of it, there is a bony arch. In the
convex forepart of this arch a small rising appears ; and on
each side of this protuberance, a small cavity may be observed.
The upper and lower parts of the arch are rough and unequal,
where the ligaments that connect this vertebrae to the os occi-
pitis, and to the second vertebra, are fixed. The back part of
the arch is concave, smooth, and covered with a cartilage, in
a recent subject, to receive the tooth-like process of the second

CERVICAL VERTEBRAE. 143

vertebra. On each side of it a small rough sinuosity may be
remarked, where the ligaments going to the sides of the tooth-
like process of the following vertebra are fastened ; and on each
side a small rough protuberance and a depression is observable,
where the transverse ligament, which secures the tooth-like
process in the sinuosity, is fixed, and hinders that process from
injuring the medulla spinalis in the flexions of the head.

The atlas has as little spinous process as body; but, instead
of it, there is a large bony arch, that the muscles which pass
over this vertebra at that place might not be hurt in extending
the head. On the posterior and upper part of this arch, there
are two depressions, where the recti postici minores muscles take
their rise ; and at the lower part are two other sinuosities, into
which the ligaments that connect this bone to the following one
are fixed.

The superior oblique processes, of the atlas are large, and
more horizontal than those of any other vertebra. They form
an oblong concave surface which has an internal aspect, and
corresponds exactly with the articulating surface on the external
side of each condyle of the os occipitis. Under the external
edge of the posterior part of each of these cavities is the fossa,
or deep open channel, in which the vertebral arteries make the
circular turn, as they are about to enter the great foramen of the
occipital bone, and where the tenth pair of nerves go out. In
some subjects, this fossa is covered with bone. The inferior
oblique processes, extending from within outwards and down-
wards, are large, circular, and slightly concave. So that this
vertebra, contrary to the other six, receives the bones with which
it is articulated, both above and below. \

The transverse processes of this vertebra are not much hol-
lowed or forked ; but are longer and larger than those of
any other vertebrae of the neck, for the origin and insertion
of several muscles ; and, therefore, those muscles which move
this vertebra on the second, have a considerable lever to act
with, because of the distance of their insertion from the axis of
revolution.

The hole for the medulla spinalis is larger in the atlas than

144 CERVICAL VERTEBRA.

in any other vertebra, not only on account of the medulla being
largest here, but also to prevent its being hurt by the motions of
this vertebra on the second. This large hole, and the long
transverse processes, make this the brqadest vertebra of the neck.
The condyles of the os occipitis move forwards and backwards
in the superior oblique processes of this vertebra ; but from the
figure of the bones forming these articulations, it is evident that
very little motion can here be" allowed to either side ; and there
must be still less circular motion.

The second vertebra of the neck is called dentata. It is
somewhat of a pyramidal figure, being large, and extended down-
wards, especially in front, to enter into a hollow of the vertebra
below ; while the upper part has a long process, with its extre-
mity formed into an obtuse point. This process, from its sup-
posed resemblance to a tooth, has given name to the vertebra.
The side of it, on which the concave surface of the anterior arch
of the first vertebra plays, is convex, smooth, and covered
with a cartilage ; and it is of the same form behind, to accom-
modate the ligament which is extended transversely from one
rough protuberance of the first vertebra to the other, and is
cartilaginous in the middle. A ligament likewise goes out in
an oblique transverse direction, from each side of the processus
dentatus, to be fixed at its other end to the first vertebra, and
Fig. 34.* to the occipital bone ; and another liga-

ment rises up from near the point of the
process to the os occipitis.

The superior oblique processes of the
vertebra dentata are large, circular,
very nearly in a horizontal position, and
slightly convex, to be adapted to the
inferior oblique processes of the first

* A lateral view of the axis or vertebra dentata. 1. The body. 2. The dentated
or odontoid process. 3. The smooth surface on the anterior face of the tooth-like
or dentated process, which articulates with the posterior face of the anterior arch
of the atlas. 4. The lamina. 5. The spinous process. 6. The transverse pro-
cess pierced obliquely by the foramen for the vertebral artery. 7. The superior
oblique or articular process. 8. The inferior articular process.

- CERVICAL' VERTEBRJE. • 145

vertebra. The inferior oblique processes of this vertebra
answer exactly to the description given of those common to
all the cervical vertebrae.

The transverse processes of the vertebra dentata are short,
very little hollowed at their upper part, and not forked at their
ends ; and the canals through which the vertebral arteries pass,
are reflected outwards about the middle of each process, so that •
the course of these vessels may be directed towards the trans-
verse processes of the first vertebra. Had this curvature of the
arteries been made in a part so movable as the neck is, while
they were not defended by a bone and placed in the cavity of
that bone, scarce a motion could have been performed without
the utmost hazard of compression. This is the third instance,
of similar mechanism in cases of sudden curvature of arte-
ries. The first is the passage of the carotids through the
temporal bones ; and the second is that lately described, where
the vertebral arteries turn round the oblique processes of the
first vertebra, to come at the great hole of the occipital bone.

The spinous process of this vertebra is thick, strong, and
short, to give sufficient origin to the musculi recti majores and
obliqui inferiores, and to prevent the contusion of the^se and
other muscles in pulling the head back.

The four cervical vertebras which are next in order have
nothing particular in their structure, but agree with the general
description. The seventh vertebra approaches the form of those
of the back, having the upper and lower surfaces less excavated
than the others. The oblique processes are more perpendicular ;
and the spinous as well as transverse processes are without
bifurcation.

After an examination of the condyles of the os occipitis, and
of the whole structure of the atlas and vertebra dentata, it will
be evident, that the flexion and extension of the head, or its
motion backwards and forwards, is effected by the movements
of the condyles of the occipital bone on the atlas ; and that in
the rotation of the head, the atlas revolves to a certain degree
round the processus dentatus of the second vertebra : the head
necessarily moving with it.
13

146 DORSAL VERTEBRJE.

The TWELVE DORSAL may be distinguished from the other
vertebra of the spine by the following marks.

Their bodies are of a middle size, between those of the neck
and loins. They are more convex before than either of the
other two sorts ; and are flattened laterally by the pressure
of the ribs, which are inserted into small cavities formed in
their sides. This flatness of their sides, which makes the figure
of these vertebrae almost a ^ialf oval, is of great use ; as it
affords a firm articulation to the ribs, allows the tracheal tube
to divide at a small angle, and the other large vessels to run
secure from the action of the vital organs. Their bodies are
more concave behind than any of the other two classes. The
upper and lower surfaces are horizontal.

The cartilages interposed between the bodies of these verte-
brae are thinner than in any other of the true vertebrae ; and
contribute to the concavity of the spine in the thorax, by being
thinnest in their forepart.

The oblique processes are placed almost perpendicularly :
the upper ones slanting but a little forwards, and the lower
ones slanting as much backwards. The convexity or concavity
is not so remarkable as to require particular notice. Between
the oblique processes of opposite sides several sharp processes
stand out from the upper and lower parts of the plates which
join to form the spinous processes : into these sharp processes
strong ligaments are fixed for connecting the vertebrae.

The transverse processes of the dorsal vertebrae are long,
thicker at their ends than in the middle, and turned obliquely
backwards, which may be owing to the pressure of the ribs ;
the tubercles of which are inserted into a depression near the
end of these processes.

The spinous processes are long, small-pointed, and sloping
downwards and backwards. From their upper and back
part a ridge rises, which is received by a small channel in the
forepart of the spinous process immediately above, which is
here connected to it by a ligament.

The canal for the spinal marrow is here more circular, but
corresponding to the size of that chord, is smaller than in any

DORSAL VEKTEBRJE. 147

of the other vertebrae; and a larger share of the holes in the
Fig. 35.* bony bridges for the transmission

of the nerves, is formed in the
vertebra above than in the one
below.

The connexion of the dorsal
vertebrae to the ribs, the thinness
of their cartilages, the erect situa-
tion of the oblique processes, the
length, sloping, and connexion of
the spinous processes, all contribu-
ting to restrain these vertebrae from

much motion, which might disturb the actions of the heart and
lungs ; and in consequence of the little motion allowed here, the
intervertebral cartilages sooner shrivel, by becoming more solid ;
and therefore the first remarkable curvature of the spine
observed, as people advance to old age, is in the least stretched
vertebrae of the back ; or old people first become round-shoul-
dered.

The bodies of the four uppermost dorsal vertebrae deviate
from the rule, that the vertebrae become larger as they descend ;
for the first of the four is the largest, and the other three below
gradually become smaller, to allow the trachea and large ves-
sels to divide at smaller angles.

The two uppermost vertebras of the back, instead of being
very prominent forwards, are flattened by the action of the
musculi longi colli and recti majores.

The proportional size of the two little depressions in the
body of each vertebra for receiving the heads of the ribs seems
to vary in the following manner : the depression on the upper
edge of each vertebra decreases as far down as the fourth, and,
after that, increases.

* A lateral view of a dorsal vertebra. 1. The body. 2. 2. Articular facets
for the head of the ribs. 3. The pedicle. 4. The superior intervertebral notch.
5. The inferior intervertebral notch. 6. The spinous process. 7. The extremity
of the transverse process marked by an articular surface for the tubercle of the
rib. 8. The two superior oblique processes looking backwards. 9. The two
inferior oblique processes looking forwards.

148 LUMBAR VERTEBRAE.

The transverse processes are longer in each lower vertebra
to the seventh or eighth, with their smooth surfaces, for the
tubercles of the ribs, facing gradually more downwards ; but
afterwards, as they descend, they become shorter, and the
smooth surfaces are directed more upwards.

The spinous processes of the vertebrse of the back become
gradually longer and more slanting from the first, as far down
as the eighth or ninth vertet5ra ; from which they manifestly
turn shorter and more erect.

The first vertebra, besides an oblong hollow in its lower
edge that assists in forming the cavity wherein the second rib
is received, has the whole cavity for the head of the first rib
formed in it.

The eleventh often has the whole cavity for the eleventh rib
in its • body, and wants the smooth surface on each transverse
process.

The twelfth always receives the whole head of the last rib,
and has no smooth surface on its transverse processes, which
are very short. The smooth surfaces of its inferior oblique
processes face outwards as the lumbar do. In general the
upper vertebra of the back lose gradually their resemblance to
x those of the neck, and the lower ones approach gradually to the
figure of the lurnbar.

Fig. 36.* The LUMBAR VERTEBRA are

five bones, that may be distin-
guished from any others by these
marks: 1. Their bodies, though
of a circular form at their fore-
part, are somewhat oblong from
one side to the other. The
epiphysis on their edges are
larger ; and therefore the upper and lower surfaces of their
bodies are more concave than in the vertebrse of the back.

* A lateral view of the lumbar vertebra. 1. The body. 2. The pedicle. 3.
The superior intervertebral notch. 4. The inferior intervertebral notch. 5. The
spinous process. 6. The transverse process. 7. The superior articular processes.
8. The inferior articular processes.

I
LUMBAR VERTEBRA. 149

The pedicles are very strong, the lamella or laminae, see page
139, are thick and narrow. 2. The cartilages between these
vertebra are very thick, and render the spine convex within
the abdomen, by their great thickness anteriorly. 3. The
oblique processes are strong and deep ; the superior, which are
concave, facing inwards, and the convex inferior ones facing
outwards ; and therefore each of these vertebrae receives the
one above it, and it is received by the one below, which is not
so evident in the other two classes already described. 4. Their
transverse processes are small, long, and almost horizontal, for
allowing large motion to each bone, and sufficient insertion to
muscles, and for supporting and defending the internal parts.
5. Between the roots of the superior oblique and transverse
processes, a small protuberance may be observed, where some
of the muscles that raise the trunk of the body are inserted. 6.
Their spinous processes are strong, straight, and horizontal, with
broad flat sides, and a narrow edge above and below; this last
being depressed on each side, by muscles ; and, at the root of
these edges, we see rough surfaces for fixing the ligaments. 7.
The medullary canal is larger in these bones than in the dorsal
vertebrae. 8. The holes for the passage of the nerves are more
equally formed out of both the contiguous vertebrae than in the
other classes ; the upper one furnishes, however, the larger share
of each hole.

The thick cartilages between these lumbar vertebrae, their
deep oblique processes, and their erect spinous processes, are all
fit for allowing large motion, though it is not so great as what
is performed in the neck ; which appears from comparing the
arches that the head describes when moving on the neck or the
loins only.

The lumbar vertebrae, as they descend, have their oblique
processes at a great distance from each other, and facing more
backward and forwards.

The transverse and spinal processes of the first and last lumbar
vertebrae are shorter than those in the middle.

The epiphyses round the edges of the bodies of the lumbar
vertebrae are most raised in the two lowest; which conse-

150 LUMBAR VERTEBRJE.

quently make them appear hollower in the middle than the
others are.

The body of the fifth vertebrae is rather thinner "than that of
the fourth. The spinous process of this fifth is smaller, and the
oblique processes face more backwards and forwards, than those
of any other lumbar vertebrae.

In consequence of this particular construction, the spine is
capable of flexion, principally in an interior and lateral direc-
tion, and also of extension. It ought to be remarked, that
during flexion it forms a curve, and not an angle ; for, in the
last case, the spinal marrow would be more or less com-
pressed.

The cervical vertebrae have most motion, and the dorsal the
least. This circumstance is fully explained by the form of the
different parts of these vertebrae, and the difference in the thick-
ness of the intervertebral substance. The necessity of fixing
the dorsal vertebrae is very evident: as their motion would
greatly interfere with the motion of the ribs in respiration.

The lumbar vertebrae have more motion than is commonly
supposed ; for, in addition to a certain degree of flexion, they
perform a species of rotation or twisting, which is very observa-
ble in persons who are diseased in one of their hip joints ; such
persons move their whole pelvis, by a rotation of the lumbar
vertebrae, to avoid moving the diseased joint.
— The first cause, the predisposing cause of spinal curvatures
is the relative feebleness of the spinal column, compared to the
forces exercised upon it, at the same time that the bones, by a
premature increase, or by a lesion of nutrition as yet little
known, do not acquire the degree of solidity necessary to resist
the action of the muscles, and especially the weight of the vis-
cera contained in the head and chest. There results from this
necessarily a curvature in some direction at one of the points of
the lever.

— The direction of the curvature will be determined by the
inequality of the forces brought into play around it. For with-
out this inequality, the curvature would be direct ; that
is, straight. It has place ordinarily to the left, because

FALSE VERTEBRA. 151

the muscles of the right side, stronger than those of the left,
draw the vertebra in that direction, as Ludvvig first pointed out. —

False Vertebra.

The lower pyramid or under part of the spine, consists of one
large triangular bone, called the os sacrum, and of some small
bones, denominated the os coccygis.

These bones are called the false vertebrae, because the sacrum
in young subjects is composed of five distinct bones, each of
which has some resemblance to a vertebra ; but they are com-
pletely united in the adult, and form but one bone, which is
supposed to have been denominated sacrum, because it was
offered in sacrifice by the ancients.

The os sacrum is of a triangular form, with its base upwards.
It is concave anteriorly, and convex posteriorly. The middle
of the bone, when viewed anteriorly, appears to be composed of
the bodies of five vertebrae, united to each other, and their union
is marked by four transverse lines. At the two extremities of;
each of these lines, are large round holes, which communicate \
with the vertebral cavity of the bone.

On the exterior sides of these holes the surface is free from
any marks of the original separation.

The middle of the upper surface, or base of the bone, is
formed for articulating with the last lumbar vertebra, and has
two oblique t- processes, with a groove in each side, which forms
part of the foramen for transmitting the twenty-fourth pair of
nerves.

The back part of the os sacrum is rough and convex ; in the
middle there are commonly three processes similar to the spinous
processes of the lumbar vertebrae, and a fourth, which is much
smaller. Below this, there is a deficiency of the bony spine,
and the vertebral cavity is consequently open behind, but the
sides of the canal continue lower down.

On each side of the spinous processes are four smaller holes,
which are opposite to the larger holes on the anterior surface.
Between the spinous processes and the anterior part, which

,

152 OS COCCYGIS.

Fig. 37.* resembles the bodies of vertebrae, is

the continuation of the vertebral
cavity which contains the spinal
marrow. From the cauda equina,
contained in this cavity, the great
nerves of the lower extremities pass
off} through the large holes on the
antwior surface, and some small
nerves through the posterior holes.

In some bones the spinous pro-
cesses are" entirely deficient, and
the cavity above mentioned is completely open behind ; but the
contained parts are defended by strong membranes.

The anterior part of each lateral surface is covered by a
plate of cartilage, and articulated to the os ilium. The poste-
rior part is rough, and perforated by the fibres of the strong
ligaments, which are inserted into it.

On the posterior surface of the sacrum, the sides of the open
part of the vertebral canal terminate, so as to form a notch
through which passes the twenty-ninth pair of nerves.

The os sacrum is very spongy, and is lighter in proportion to
its bulk than any bone in the body: it is defended by the
muscles that cover it, and the ligaments which adhere to it. It
is articulated, above, to the last lumbar vertebrae ; below, to the
os coccygis by its apex and two cornua ; and on the sides, to
the ossa ilia.

That triangular chain of bones depending from the os
sacrum, in which each bone becomes smaller as it descends,
till the last ends in a small tubercle, is called os coccygis. It
is convex behind, and concave before ; from which crooked

* The sacrum seen upon its anterior surface. 1, 1. The transverse lines
marking the original constitution of the bone of four pieces. 2, 2. The anterior
sacral foramina. 3. The promontory of the sacrum. 4. The ear-shaped surface
which articulates with the ilium. 5. The sharp edge to whjch the sacro-ischiatic
ligaments are attached. 6. The vertebral 'articular surface. 7. The broad tri-
angular surface which supports the psoas muscle and lumbosacral nerve. 8.
The articular process of the right side. 9. The inferior extremity, or apex of
the sacrum. 10. One of the sacral cornua. 11. The notch which is converted
into a foramen by the coccyx.

OS COCCYGIS. 153

pyramidal figure, which was thought to resemble a cuckoo's
beak, the name is derived.

There are four pieces in people of middle age. In children,
they are almost wholly cartilaginous. In old subjects, all the
bones are united, and become frequently one continued bone
with the os sacrum.

The highest of the four bones is the largest, with shoulders
extended farther to each side than the end of the os sacrum ;
which enlargement may serve as a distinguishing mark to fix
the limits of either bone. The upper surface of this bone is a
little hollow. From the back of that bulbous part called its
shoulders, a process often rises up on each side, to join with
the os sacrum. Sometimes these shoulders are joined to the
sides of the open end of the vertebral canal, to form the hole
in each side common to these two bones, for the passage of the
twenty-ninth pair of spinal nerves. Immediately below the
shoulders of the os coccygis, a notch may be remarked on each
side, where the thirtieth pair of the spinal nerves passes. The
lower end of this bone is formed into a small head, which very
often is hollow in the middle.

The three lower bones gradually become smaller, and are
spongy,, but are strengthened by a strong ligament, which
covers and connects them. Their ends, by which they are
articulated, are formed in the same manner as those of the first
bone.

Between each of these four bones of young subjects a carti-
lage is interposed ; therefore their articulation is analogous to
that of the bodies of the vertebrae of the neck ; for the lower
end of the os sacrum, and of each of the three superior bones
of the os coccygis, has a small depression in the middle ; and
the upper part of all the bones of the os coccygis, is a little
concave, and, consequently, the interposed cartilages are thick-
est in the middle, to fill up both cavities ; by which they
connect the bones more firmly. When the cartilages ossify,
the upper end of. each bone is formed into a cavity, exactly
adapted to the protuberant lower end of the bone immediately
above. From this sort of articulation, it is evident that, unless

154 VERTEBRAL CAVITY.

when these bones grow together, all of them are capable of
motion ; of which the first and second enjoy the largest share.

The lower end of the fourth bone terminates in a rough point,
to which a cartilage is appended.

To the sides of these bones of the os coccygis, the coccygaei
muscles, and part of the levatores ani, and of the glutaei maximi,
are fixed.

The connexions of thes% bones hinder them from being
moved to either side ; and their motion backwards and for-
wards is much confined : yet, as their ligaments can be stretched
by a considerable force, it is of great advantage in the excretion
of the faeces alvinae, and much more in child-bearing, that these
bones should remain movable ; and the right management of
them, in delivering women, is very important. The mobility
of the os coccygis diminishing as people advance in age,
especially when its ligaments and cartilages have not been
kept flexible by being stretched, is, probably, one reason why
women, who are advanced in years before they marry, have gen-
erally difficult parturition.

These bones serve to sustain the intestinum rectum ; and,
therefore, are curved forwards ; by which they are preserved,
as well as the muscles and teguments, from any injury when
sitting with the body inclined back.

The Vertebral Cavity for containing the Spinal Marrow.

The canal, formed by the foramina of the different vertebrae,
when these bones are placed in their natural order, extends
from the great occipital foramen to the end of the sacrum. Its
direction varies with the different curvatures of the spine, and
its figure and diameter are also very different in different
places.

In the cervical vertebrae, it is largest, and nearly triangular
in form ; in the dorsal, it is much smaller and almost cylin-
drical ; in the lumbar, it is somewhat enlarged, and approaches
again to the triangular figure ; in the sacrum, it is broad, but flat,
and diminishes gradually, so as to assume the form of a long
triangle.

THE RIBS. 155

It has a ligamentous lining, which will be described, when an
account is given of the fresh bones and their ligaments.

The Thorax.

The thorax resembles a flattened cone, cut away obliquely at
its basis ; and regularly truncated at its apex.

It is formed by the dorsal vertebrae behind, the ribs on the
sides, and the sternum before.

The Ribs

Are long crooked bones, placed in an oblique direction
downwards as respects the back-bone. - Their number is gene-
rally twelve on each side ; though sometimes eleven or thirteen
have been found.

They are convex externally, and concave internally. They
are made smooth by the action of the contained parts, which, on
this account, are in no danger of being hurt by them.

The ribs approach towards a round form at their extremities,
near the vertebrae. Farther forwards they are flat and broad,
and have an upper and lower edge ; each of which is made
rough by the action of the intercostal muscles inserted into
them. These muscles being all of nearly equal force, and
equally stretched in the interstices of the ribs, prevent the
broken ends of these bones, in a fracture, from being removed
far out of their natural place, to interrupt the motion of the vital
organs. The upper edge of the ribs is more obtuse, and
rounder than the lower, which is deepened on its internal side
by a long fossa, for lodging the intercostal vessels and nerves :
on each side of which there is a ridge, to which the intercostal
muscles are fixed. The fossa is not observable at the ends of
the ribs ; for, at the posterior, or root, the vessels have not yet
reached the bones ; and, at .the fore end, they are split away
into branches, to serve the parts between the ribs.

From this situation of the blood-vessels, has originated the
rule adopted by surgeons, that the incision, in cases of empyema,
&c., should be made midway between the spine and sternum,
and that the lower edge of the upper rib should be avoided.

* ' • ~ ^

/?'

^/

156

THE RIBS.

Fig. 38.* At the posterior end of

each rib, a little head is
formed, which is divided
by a middle ridge into two
flat or hollow surfaces ;
the lowest of which is ge-
nerally the broadest and
deepest. The two surfaces
are joined to the bodies of
two different vertebrae,
and the ridge forces itself
into the intervening carti-
lages. A little way from
this head, we find, on the
external surface, a small
cavity, where mucilagi-
nous glands are lodged ;
and round the head, the bone appears spongy, where the
capsular ligament of the articulation is fixed. Immediately
beyond this, a flattened tubercle rises, with a small cavity at
its root, which is surrounded by a roughness, for the articula-
tion of the rib with the transverse process of the lowest of the
two vertebrae, with which the head of the rib is joined.
Advancing farther on this external surface, another smaller
tubercle may be observed in most cases, into which ligaments
connecting the ribs to each other, and to the transverse pro-
cesses of the vertebrae and portions of the longissimus dorsi,
are inserted. Beyond this, these bones are made flat by the
sacro-lumbalis muscle, which is inserted into the part of this
flat surface farthest from the spine, where each rib makes a
considerable curve, called by some its angle. Then the rib

* An anterior view of the thorax. J . The superior piece of the sternum. 2.
The middle piece. 3. The inferior piece, or ensiform cartilage. 4. The first
dorsal vertebra. 5. The last dorsal vertebra. 6. The first rib. 7. Its head.

8. Its neck, resting against the transverse process of the first dorsal vertebra.

9. Its tuberosity. 10. The seventh or last true rib. 11. The costal cartilages of
the true ribs. 12. The two last false ribs — the floating ribs. 13. The groove
along the lower border of the rib for the lodgment of the intercostal vessels and
nerve.

THE RIBS. 157

begins to turn broad, and continues so to its anterior end, which
is hollow and spongy, for the reception of, and firm coalition
with, the cartilage that runs thence to be inserted into the^ter-
num, or to be joined with some other cartilage. In adults, the
cavity at this end of the ribs is generally smooth.

The substance of the ribs is spongy, cellular, and only covered
with a very thin external lamellated surface, which increases in
thickness and strength as it approaches the vertebrae.

To the fore end of each rib a long, broad, and strong cartilage
is fixed, which reaches the sternum, or is joined to the cartilage
of the next rib. This course, however, is not in a straight line
with the rib : for the cartilages generally make a considerable
flexure, the concave part of which is upwards; therefore, at
their insertion into the sternum, they make an obtuse angle
above, and an acute one below. These cartilages are of such a
length as never to allow the ribs to come to a right angle with
the spine ; but they keep them situated so obliquely as to make
the angle very considerably obtuse above, till a force exceeding
the elasticity of the cartilage is applied. These cartilages, as
all others, are firmer and harder internally than they are on
their external surface ; and, sometimes, in old people, all their
middle substance becomes bony, while a thin cartilaginous
lamella appears externally. The ossification, however, begins
frequently at the external surface. The greatest alternate
motions of the cartilages being made at their great curvature,
that part remains frequently cartilaginous after all the rest is
ossified.

The ribs then are articulated at each end, and that behind
is doubly joined to the vertebrae ; for the head is received into
the cavities of two bodies of the vertebra?, and a larger tubercle
is received into the depression in the transverse process of the
lower vertebrae. When we examine the double articulation, we
must immediately see, that no other motion can here be allowed
than upwards and downwards. Since the transverse process
hinders the ribs to be thrusted back, the resistance of the sternum
on the other side prevents the ribs coming forward ; and each
of the two joints, with the other parts attached, oppose its
14

158 THE RIBS.

turning round. But then it is likewise as evident, that even
the motion upwards and downwards can be but small in any
one rib at the articulation itself. But as the ribs advance
forwards, the distance from their centre of motion increasing,
the motion must be larger ; and it would be very conspicuous
at their anterior ends, were they not resisted there by the car-
tilages which yield so little, that the principal motion is per-
formed by the middle part of the ribs, which turns outwards
and upwards, and occasions the twist remarkable in the long
ribs at the place near their fore end where they are more
resisted.

The ribs differ from each other in the following respects :
The upper rib is the most crooked ; and as they descend
they become straighter. Their obliquity, with respect to the
spine, increases as they descend, so that though their distances
from each other are nearly equal at their back part, yet at their
fore ends the distances between the lower ribs must increase.
In consequence of this increased obliquity of the lower ribs,
each of their cartilages makes a greater curve in its progress
from the rib towards the sternum ; and the tubercles that are
articulated to the transverse processes of the vertebrae, have
their smooth surfaces gradually facing more upwards. The
ribs becoming thus more oblique, while the sternum advances
forwards in its descent, makes the distance between the sternum
and the anterior end of the lower ribs greater than between the
sternum and the ribs above ; consequently, the cartilages
of those ribs that are joined to the breast bone are longer in the
lower than in the higher ones. These cartilages are placed
nearer to each other as the ribs descend, which occasions their
curvature to be greater.

The length of their ribs increases fromthe first and upper-
most rib, as far down as the seventh ; and from that to the
twelfth, it gradually diminishes. The superior of the two
surfaces, by which the ribs are articulated to the bodies of the
vertebras, gradually increases from the first to the fourth rib,
and is diminished after that in each lower rib. The distance
of their angles from the heads always increases as they

THE RIBS. 159

descend to the ninth, because of the greater breadth of the sacro-
lumbalis muscle.

The ribs are commonly divided into true and false.

The true ribs are the seven uppermost of each side. Their
cartilages are all gradually longer as they descend, and are joined
to the breast bone : so that, being pressed constantly between
two bones, they are flattened at both ends ; and are thicker,
harder, and more liable to ossify than the other cartilages that
are not subject to so much pressure. These bones include the
heart and lungs ; and therefore are called true ribs.

The five inferior ribs of each side are the false, whose carti-
lages do not reach to the sternum ; but on this account having
less pressure, their substance is softer. To these five ribs the
circular edge of the diaphragm is connected.

The first rib of each side is so situated, that the flat sides are
above and below, while one edge is placed inwards, and the
other outwards, or nearly so ; therefore sufficient space is left
above it for the subclavian vessels and the muscles ; and the
broad concave surface is opposed to the lungs. But in conse-
quence of this situation, the channel for the intercostal vessels is
not to be found. The head of this rib is not divided into two
plane surfaces by a middle ridge, because it is only articulated
with the first vertebra of the thorax. Its cartilage is frequently
ossified in adults, and is united to the sternum at right angles.
This first rib frequently has a ridge rising near the middle of its
posterior edge, where one of the heads of the scalenii muscles
rises. Farther forward it is flattened, or sometimes depressed
by the clavicle.

The position of the second rib is such that its two broad
surfaces have oblique aspects, inward and downwards, outwards,
and upwards, so as to make the surface of the thorax uniform :
and it may be observed of all the ribs, that the aspect of their
surfaces is varied upon this principle, according to their situation
in the thorax.

The sixth, seventh, and eighth ribs have their cartilages
nearly contiguous. They are frequently joined to each other
by cross cartilages ; and frequently the cartilages of the eighth,

160 THE STERNUM.

ninth, and tenth, are connected to the former, and to each other
by firm ligaments.

The eleventh, and sometimes the tenth rib, has no tubercle
for its articulation with the transverse process of the vertebra,
to which it is only loosely fixed by ligaments. The fossa, in its
lower edge, is not so deep as in the upper ribs ; because the
vessels run more towards the interstice between the ribs. Its
front end is smaller than its Ibody ; and its short small cartilage
is but loosely connected to the cartilage of the rib above.

The twelfth rib is the shortest and straightest. Its head is
only articulated with the last vertebra of the thorax ; and
therefore is not divided into two surfaces. This rib is not
joined to the transverse process of the vertebra, and therefore
has no tubercle, being often pulled necessarily inwards by the
diaphragm, which an articulation with the transverse process
would not have allowed. The fossa is not found at its upper
edge, because the vessels run below it. The forepart of this
rib is smaller than its middle, and has only a very small pointed
cartilage fixed to it. To its whole internal side the diaphragm
is connected.

The Sternum

Is the broad flat bone, in the front part of the thorax. In
adults it is composed of three pieces, which easily separate
after the cartilages connecting them are destroyed. . The two
lower pieces are frequently found intimately united ; and very
often, in old people, the sternum is a continued bony substance
from one end to the other ; though we still observe two, some-
times three, transverse lines on its surface ; which are marks of
the former divisions.

The sternum, considered as one bone, is broadest and thickest
above, and smaller as it descends. The internal surface of this
bone is somewhat concave for enlarging the thorax : but the
convexity on the external surface is not so conspicuous, because
the sides are pressed outwards by the true ribs ; the round
heads of whose cartilages are received into seven smooth pits,
formed in each side of the sternum, and are kept firm there by

THE STERNUM. 161

strong ligaments, which, on the external surface, have a par-
ticular radiated texture. The pits, at the upper part of the
sternum, are at the greatest distance one from another, and
as they descend, are nearer ; so that the two lowest are con-
tiguous.

The substance of the breast bone is cellular, with a very thin
external plate, especially on its internal surface, where we may
frequently observe a cartilaginous crust spread over it. On
both surfaces, however, a strong ligamentous membrane is
closely braced ; and the cells of this bone are so small, that a
considerable quantity of osseous fibres must be employed in
the composition of it. Whence, with the defence which the
muscles give it, and the movable support it has from the
cartilages, it is sufficiently secured from being broken : for it is
strong by its quantity of bone ; its parts are kept together by
ligaments ; and it yields enough to elude considerably any
violence offered.

The three pieces which compose this bone are very different
from each other.

The first piece resembles a triangle, with the corners cut off.
The upper edge of it is thick, and has a regular depression in
the middle, to accommodate the trachea. On each side of this
depression is a superficial cavity, which, on viewing it trans-
versely, from before backwards, appears a little convex. Into
these cavities the ends of the clavicles are received. Imme-
diately below them, the sides of this bone become thinner ; and
in each a superficial cavity, or a rough surface is to be seen,
where the first ribs are received or joined to the sternum. In
the side of the under end of this first bone, the half of the pit
for the second rib on each side is formed. The upper part of
the surface behind is covered with a strong ligament, which
secures the clavicles ; and is afterwards to be more particularly
taken notice of.

The second, or middle division of this bone, is much longer,
narrower, and thinner, than the first; but, excepting that it is
a little narrower above than below, it is nearly uniform in its
14*

162 THE STERNUM.

dimensions of breadth or thickness. In the sides of it are com-
plete pits for the third, fourth, fifth, and sixth ribs, and one
half of the pits for the second and seventh ; the lines, which
are marks of the former division of this bone, being extended
from the middle of the pits of one side, to the middle of the
corresponding pits of the other side. Near its middle an un-
ossified part of the bone has sometimes been found ; which,
freed of the ligamentous membrane or cartilage that fills it, is
described as a hole. When the cartilage between this and the
first bone is not ossified, a manifest motion of this upon the
first may be observed in respiration ; or in raising the sternum,
by pulling the ribs upwards ; or distending the lungs with air,
in a recent subject.

The third bone is much less than the other two, and has
only one half of the pit for the seventh rib formed in it ; where-
fore it might be reckoned only an appendix of the sternum.
In young subjects it is always cartilaginous, and is better known
by the name of cartilago-xiphoides or ensiformis, than any
other. This third bone is seldom of the same figure, mag-
nitude, or situation, in any two subjects ; for, sometimes, it is
triangular ; with one of the angles below, and perpendicular to
the middle of the upper side, by which it is connected to
the second bone. In other persons, the point is turned to
one side ; or obliquely forwards or backwards. Frequently it
is nearly of an equal breadth, and often it is bifurcated ; some-
times, also, it is unossified in the middle. In the greatest number
of adults, it is ossified, and tipped with a cartilage ; in some,
one half of it is cartilaginous ; and in others, it is all in a car-
tilaginous state.

The sternum is joined by cartilages to the seven upper ribs,
except when the first coalesce with it. It is also articulated
with the clavicles.

It contributes to the formation of the cavity of the thorax,
and supports the mediastinum. As a movable fulcrum for the
ribs, it assists in respiration ; and it affords origin and insertion
to several muscles.

THE PELVIS. 163

The movement of the Ribs and Sternum in respiration.

The ribs and their cartilages are articulated to the spine
behind, and the sternum before, in a way which admits of a
compound motion.

They are drawn from a position which slopes obliquely
downwards and forwards, into one which is more horizontal ;
and the posterior extremity of each rib, which is the centre of
this motion, is moved very little, while the anterior extremity
moves much more.

At the same time, the ribs perform a rotation outwards,
upon their extremities connected with the spine and sternum ;
in consequence of which, the middle of each rib is moved out-
wards to a considerable extent.

It is very obvious, that, by these motions, the thorax must be
enlarged from side to side, and from behind forwards.

As the ribs are raised from the oblique towards the horizontal
position, the sternum is necessarily moved forward by them;
and, if this bone does not move upon the first rib, the rib must
move to accommodate it : a small motion at the articulation of
the rib with the spine, being sufficient to produce considerable
motion at the lower end of the sternum. The sternum, there-
fore, vibrates forward when the ribs are elevated, and backward
when they are depressed.

In easy respiration, these motions are not very great, for then
the enlargement of the thorax appears to be produced by the
increase of its vertical diameter, in consequence of the descent
of the diaphragm ; but when the inspirations are very large,
and when the descent of the diaphragm is impeded, as in
pregnancy, and in a^cites, these motions are very considerable.

It ought to be observed, that the first rib has very little motion,
except the rotation which favors the motion of the sternum ; and
that the lower ribs, having no support at their anterior extremi-
ties, have no rotation.

The Pelvis.

The pelvis is the cavity at the lower part of the trunk, formed
by the os sacrum, os coccygis, and ossa innominata.

164

OS ILIUM.

The ossa innominata are the two large bones which are con-
nected to the sacrum behind, and to each other by the interven-
tion of a cartilage in front.

Each of the ossa innominata is composed of three portions, in
children ; and although these are united in adults, so as to form
but one bone,- yet anatomists have generally considered the bone
as divided into its original parts, which are denominated os ilium,
os ischium, and os pubis.

The original separation was at the acetabulurn, or cavity for
receiving the head of the os femoris, which is on the outside o{
the os innominatum. The upper and posterior part of this cavity,
to the amount of two-fifths, is formed by the os ilium, two-fifths
of the inferior portion by the os ischium, and the anterior fifth
by the os pubis.

The Os Ilium

Fig. 39.* Is the largest of the three

portions. Its external sur-
face has been called its
dorsum, and the internal
concave surface its costa or
venter. The semicircular
edge at the upper part of the
bone, is named the spine or
crest; the external oblique
muscle of the abdomen is in-
serted into it, and the inter-
nal oblique, and the transver-
salis arise from it. The ends
of the spine are prominent,
and therefore are'called pro-

* The os innominatura of the right side. 1. The ilium ; its external surface.
2. The ischium. 3. The os pubis. 4. The crest of the ilium. 5. The superior
curved line. 6. The inferior curved line. 7. The surface for the glutens maxi-
mus. 8. The anterior superior spinous process. 9. The anterior inferior spinous
process. 10. The posterior superior spinous process. 11. The posterior inferior
spinous process. 12. The spine of the ischium. 13. The great sacro-ischiatic
notch. 14. The lesser sacro-ischiatic notch. 15. The tuberosity of the ischiurfij
showing its four surfaces. 16. The ramus of the ischium. 17. The body of the
os pubis. 18. The ramus of the pubis.

OS ILIUM. 165

cesses. In front the crest terminates in the anterior superior
spinous process ; below this is another protuberance, called
the inferior anterior spinous process ; and the edge of the bone
between these two processes is curved.

Behind the crest terminates in the posterior superior spinous
process ; below this another protuberance is also observable,
(post. inf. spin, process) which is applied closely to the os
sacrum. Under this is a large notch, which, with the ligaments
that pass from the os sacrum to the os ischium, forms a foramen,
through which the great sciatic nerve, the pyriform muscle,
and some blood-vessels pass.

The external surface, or, dorsum, of the os ilium, is greatly
undulated by the action of muscles that lie upon it ; the gluteus
maximus, on the posterior, and the gluteus medius and minimus,
on the anterior parts of it. The lower part of this bone, which
contributes to the formation of the acetabulum, is the thickest.

The internal surface of the os ilium is concave, and supports
some of the intestines. From this concave surface a slight con-
cavity is continued obliquely forwards, at the inside of the
anterior inferior spinous process, where part of the psoas and
iliacus muscles, with the crural vessels and nerves pass. The
large concavity is bounded below by a sharp ridge, which runs
from behind forwards ; and, being continued with such another
ridge of the os pubis, forms a line of partition between the
cavities of the abdomen and pelvis. Into this ridge called linea
ilia innominata the broad tendon of the psoas parvus is
inserted.

All the internal surface of the os ilium, behind the continu-
ance of this ridge, is very unequal : for the upper part is flat,
but spongy, where the sacro-lumbalis and longissimus dorsi
rise. Lower down, there is a transverse ridge from which
ligaments go out to the os sacrum. Immediately below this
ridge, the rough unequal cavities and prominences are placed,
which are exactly adapted to those described on the side of the
os sacrum. In the same manner, the upper part of this rough
surface is porous, for the firmer adhesion of the ligamentous
cellular substance ; while the lower part is more solid, and
covered with a thin cartilaginous skin, for its immovable arti-

166 OS ISCHIUM.

culation with the os sacrum. From all the circumference of
this large unequal surface, ligaments are extended to the os
sacrum, to secure more firmly the conjunction of these bones.

The passages of the medullary vessels are very conspicuous,
both in the dorsum and costa of many ossa ilia ; but in others
they are inconsiderable.

The posterior and lower parts of these bones are thick; but
they are generally exceeding!^ thin and compact at their
middle, where they are exposed to the actions of the musculi
glutaei and iliacus internus, and to the pressure of the bowels
contained in the belly. The substance of the ossa ilia is cellu-
lar, except a thin external plate.

The Os Ischium,

Or, hip-bone, is of a middle size, between the two other parts
of the os innominatum, and of a very irregular figure. Its
extent might be marked by a horizontal line drawn a little
below the middle of the acetabulum ; for the upper bulbous
part of this bone forms rather less than the lower half of that
great cavity, and the small leg of it rises to much the same
height on the other side of the great hole common to this
bone and the os pubis.

From the upper thick part of the os ischium, a sharp process,
called by some authors spinousj stands out backwards, from
which chiefly the musculus coccygaeus and superior gemellus,
and part of the levator ani, rise ; and the anterior, or internal
sacro-sciatic ligament is fixed to it. Between the upper part
of this ligament and the bones, it was formerly observed, that
the pyriform muscle, the posterior crural vessels, and the
sciatic nerve, pass out of the pelvis. Immediately below this
process, is a depression for the tendon of the obturator internus
muscle. In a recent subject, this part of the bone serves as a
pulley on which the obturator muscle plays with a ligamentous
cartilage.

Below the depression of the obturator muscle, is the great
knob or tuberosity, covered with cartilage or tendon. The
upper part of the tuberosity gives rise to the inferior gemellus

os PUBIS. 167

muscle. To a ridge at the inside of this, the external, or pos-
terior sacro-sciatic ligament is so fixed, that between it, the
internal ligament, and the sinuosity of the os ischium, a passage
is left for the internal obturator muscle. The upper thick
smooth part of the tnber, called by some its dorsum, has two
oblique impressions on it. The inner one gives origin to the
long head of the biceps flexor cruris, and semitendinosus
muscles ; and the semimembranosus rises from the exterior one,
which reaches higher and nearer the acetabulum than the
other. The lower, thinner, more scabrous part of the knob,
which bends forwards, is also marked with two flat surfaces ;
whereof the internal is what we lean upon in sitting, and the
external gives rise to the largest head of the triceps adductor
femoris. Between the external margin of the tuberosity, and
the great hole of the os innominatum, there is frequently an
obtuse ridge extended down from the acetabulum, which
gives origin to the quadratus femoris. As the tuber advances
forwards, it becomes smaller, and is rough for the origin of the
musculus transversalis and erector penis. The small leg of it,
which mounts upwards to join the os pubis, is rough and prom-
inent at its edge, where the two lower heads of the triceps
adductor femoris take their rise.

The upper and back part of the os ischium is broad and
thick ; but its lower and forepart is narrower and thinner. Its
substance is of the structure common to broad bones.

The os ilium and pubis, of the same sides, are the only
bones which are contiguous to the os ischium.

The Os Pubis,

The least of the three portions of the os innominatum, is
placed at the upper and front part of it. The thick, largest
part of this bone is employed in forming the acetabulum ; from
which, becoming much smaller, it is stretched inwards to its
fellow of the other side, where it again grows larger, and
forms a surface to be connected with the cartilage of its sym-
physis and then sends a small branch downwards to join the

168 os PUBIS.

end of the small leg of the os ischium. The upper surface of
each os pubis is broad, near its junction with the cartilage of
the symphysis ; on the internal edge of this surface begins a
ridge, which is continued from it along the os ilium, and forms
the division between the cavities of the abdomen and pelvis.
This ridge is called crista, and including that on the ilium, forms
the linea innominata, or ileo-pectinea. On the anterior and ex-
ternal edge of this surface of the pubis, at a small distance from
the cartilage, is a prominence or process, called the spine. From
this process, another ridge, which is much more obtuse, extends
to the acetabulum. The upper surface of the pubis, which is
included between these ridges, is concave, for the transmission
of the crural vessels and nerve, and the psoas and iliacus
internus muscles.

Immediately below the lower ridge, and near the acetabu-
lum, a winding notch is made, which is comprehended in the
great contiguous foramen ; but is formed into a hole in the
recent subject by a subtended ligament, for the passage of the
posterior crural nerve, and artery, and vein. The internal end
of the os pubis is rough and unequal, for the firmer adhesion
of the thick ligamentous cartilage that connects it to its fellow
of the other side. The process which goes down from that to
the os ischium is broad and rough before, where the gracilis
and upper heads of the triceps adductor femoris have their
origin.

The substance of the os pubis is the same as that of other
broad bones.

Between the os ischium and pubis a very large irregular hole
is left, which has been called obturator, thyroid. The whole of
this foramen, except the notch for the posterior crural nerve, is
filled up, in a recent subject, with a strong ligamentous mem-
brane, that adheres very firmly to its circumference. From
this membrane chiefly, the two external and internal obturator
muscles take their rise. The great design of this hole, besides
rendering the bone lighter, is, to allow a strong origin to the
obturator muscles, and sufficient space for lodging them ; that
there may be no danger of disturbing the functions of the con-

ACETABULUM. 169

tained viscera of the pelvis by the actions of the internal ; nor
of the external being bruised by the thigh bone, especially by
its lesser trochanter, in the motions of the thigh inwards : both
which inconveniences must have happened, had the ossa mnom-
inata been complete here, and of sufficient thickness and
strength, as the fixed point of these muscles.

The bowels sometimes make their way through the notch
for the vessels at the upper part of this thyroid hole ; and this
causes a hernia at this place.

The acetabulum is situated near the outside of the great
foramen. The margin of this cavity is very high, and is still
much more enlarged by the ligamentous cartilage, with which
it is tipped in a recent subject; round the base of this margin
the bone is rough and unequal, where the capsular ligament of
the articulation is fixed. At the upper and back part of the
acetabulum the margin is much larger and higher than any
where else ; which is very necessary to prevent the head of the
femur from slipping out of its cavity at this place, where the
whole weight of the body bears upon it, and consequently
might otherwise thrust it out. As the margin is extended
downwards and forwards, it becomes less ; and, at the internal
lower part, is a deficiency in it ; from the one side of which to
the other, a ligament is placed in the recent subject, under
which a large hole is left. Besides this difference in the height
of the margin, the acetabulum is otherwise unequal ; for the
lower internal part of it is depressed below the cartilaginous
surface of the upper part, and is not covered with cartilage ;
into the upper part of this particular depression, where it is
deepest, and of a semilunar form, the ligament of the thigh
bone, commonly, though improperly called the round one, is
inserted : while, in its more superficial lower part, a mass of
adipose matter is lodged. The greatest part of this separate
depression is formed in the os ischium.

The ossa innominati are joined, at their back part, to each

side of the os sacrum, by a sort of suture, with a very thin

intervening cartilage, which serves to cement these bones

together: and strong ligaments go from the circumference of

15

170 CAVITY OF THE PELVIS.

this unequal surface to connect them more firmly. They are
connected together at their forepart by the ligamentous cartilage
interposed between the two ossa pubis, and therefore have no
motion in a natural sjate, except what is common to the trunk
of the body, or to the os sacrum.

Considering the great weight that is supported in our erect
posture, by the articulation of the ossa innominati with the os
sacrum, there is great reason to think, that, if the conglutinated
surfaces of these bones were once separated, (without which
the ossa pubis cannot move on each other,) the ligaments
would be violently stretched, if not torn.

Each os innominatum affords a socket (the acetabulum) for
the thigh bones to move in ; and the trunk of the body rolls so
much on the heads of the thigh bones as to allow here the most
conspicuous motions of the trunk, which are commonly thought
to be performed by the bones of the spine.

The form of the cavity of the pelvis, at its upper opening, or
brim, is somewhat oval ; as a line drawn from one side to the
other, is about an inch longer than a line drawn from the back
to the front part of it.

This margin is well defined by the ridge on the surface of
the ossa ilia, and the upper edge of the os pubis ; but the
margin of the lower opening is very irregular ; and it ought to
be observed, that the dimensions of this opening are made less
by the sacro-sciatic ligaments, than they appear upon an
examination of the bare bones.

In consequence of the oblique position of the sacrum,
sloping downwards and backwards, the position of the pelvis
is very oblique. A line drawn through the centre of this
cavity, perpendicular to the plane of the upper orifice, or brim,
would not coincide with the vertical diameter of the cavity of
the abdomen, but would pass out of that cavity near the
umbilicus.

This cavity, and the bones which form it, are different in the
two sexes.

In women, the brim of the pelvis is wider, and inclines more
to the oval form.

In men this opening is more circular.

CAVITY OF THE PELVIS. 171

The outlet or lower opening of the pelvis is also larger in
women.

This greater size of the pelvis and its openings, in women, is
derived particularly from the following circumstances :

The os sacrum is broader, and sometimes straighter than in
men.

The ossa ilia are flatter, and consequently the ossa ischia are
farther apart.

The ligamentous cartilage at the symphysis pubis is broader,
and shorter.

The angle formed by the crura of the ossa pubis with each
other, at the symphysis, is much larger.

— The pelvis, considered as a whole, is very irregular, though
symmetrical in its shape. It has the form of a truncated cone,
or a funnel with its base upwards, curved from behind forward
with its concavity in front, and is bounded both above and
below by bony walls of unequal elevation. It is divided by the
projection of the base of the sacrum and the two ilio-pectineal
lines, into a greater and lesser pelvis, the former of which is
above. The dividing line is called the superior strait of the
lesser pelvis. The bony walls of the greater pelvis is incom-
plete. The boundaries of this cavity, are formed upon the
sides by the iliac fossa?, and behind by a notch which is nearly
filled up, when the last lumbar vertebrae is left connected with
the sacrum ;* and in front by all the wide triangular opening be-
tween the anterior superior spine of the ^lium of each side and
the symphysis pubis'which is filled up by the lower part of the
abdominal muscles. From the flaring direction of the upper
part of the ilia, the diameters of the base of this cavity, or that
towards the abdomen, is greater than those opposite the ilio-
pectineal lines.

— The lesser pelvis, forms nearly an entire bony canal, and
which the student is too apt to consider as constituting the whole
pelvis. This cavity is larger at its middle than at its extremities.
It is bounded behind by the sacrum and coccyx ; in front by the

* The attachment of the lumbar muscles completes this wall behind.

j, ,-f?

to ^^L^Lr

172 DIMENSIONS OF THE PELVIS.

symphysis pubis and a part of the obturator foramen ; and upon
the sides, by the bony surface which corresponds to the cotyloid
cavity. Its superior margin (superior strait,) is regular and
ovoidal in its shape. Its longest diameter is transverse. Its
inferior strait is very irregular, though symmetrical in the form
of its bony walls ; and in consequence of the posterior walls of
this pelvis being of much greater length than the anterior,
presents an oblique cut, which faces slightly forwards,
so that if its axis was extended downwards, it would
cross just above the middle of the thigh. It is bounded
behind, by the point of the coccyx ; in front, by the sym-
physis pubis ; and on the side, by the tuberosities of the
ischium. The sacro-sciatic notches and the arch of the pubis,
are filled up by ligaments and soft parts. From the general
form of the whole pelvic cavity it will then be obvious, that a
body passing through its axis from above downwards, must
advance successively in three directions : 1st, as it passes
through the greater pelvis, obliquely backwards ; 2d, vertically ;
and 3d, as it passes through the inferior strait, obliquely
forwards.

— For obstetrical purposes, it is necessary for the student to
have precise notions in regard to the dimensions of the pelvis.
To determine this, it is necessary to measure the superior
opening of the greater pelvis, and the two straits of the
lesser.

— The pelvis of the male, differs in many respects from that of
the female. In the former length predominates, in the latter,
breadth. In the female all the diameters of the pelvis are more
extensive than those of the male, which is caused by the greater
size and outward direction of the iliac fossae, from a less degree
of curvature in the iliac crests, and from the roundness of the
pubic arch which in the male forms an acute angle. In conse-
quence of the wider space which exists between -the cotyloid
cavities, the gait of the female is characterized by more lateral
rotation or waddling, than that of man. A

— In a well formed woman, the different measurements are
nearly as follows :

TRUNK OF THE FOETUS. 173

Greater Pelvis.

- — In the superior opening of the greater pelvis, we distinguish
but two diameters, both transverse. The posterior extended
from the middle of one iliac crest to the other, eleven mches.
The anterior, between the two anterior superior spinous processes
of the ilium, ten inches. From the middle of the iliac crest, to
the superior strait, three and a half inches. From the middle
of the iliac crest to the tuberosity of the ischium, (whole depth
of the pelvis) seven and a half inches nearly.*

Lesser Pelvis.

Superior Strait, sometimes called ab- Inferior Strait, or perineaL

dominal.

Inches. Inches.

Antero-posUrior diameter, from Antero-posterior diameter, be-

the symphysis of the pubis to the tween the symphysis pubis andS

promontory of the sacrum, - - 4 front of the coccyx, which may be
Transverse, or iliac, which increased near an inch by the mo-

crosses the former, at a right bility of the coccyx backwards, 4

angle, ------ 5 Transverse, or ischiatic, from

Oblique, from the acetabulum of one tuberosity of the ischium to

one side, to the sacro-iliac, articu- the other, ----- 4

Lation of the other, - - - 4.J. Oblique, from the tuberosity of

the ischium of one side, to the mid-
dle of the great sacro sciatic liga-
ment of the other, nearly 4

The height of the posterior wall of the lesser pelvis,
formed by the sacrum and coccyx, (of which the

latter forms an inch,) is nearly - - 5 inches.

Height of the anterior wall formed by the os pubis, 1| "

Height of the lateral walls, - - 3J "

Thickness of the symphysis pubis, about - \ "

Depth or sine of the cavity of the sacrum,f nearly - I "

The Trunk of the Fcstus.
At birth, each vertebra consists of three pieces, connected by

* The depth or length of the pelvis is rather greater in the male than in the
female.

f Dimensions of the child's head at birth. The long diameter, from the
vertex or posterior extremity of the sagittal suture to the chin, 5 1-4 inches ;
antero- posterior, from the middle of the frontal bone to the tubercle of the
occipital, 4 inches; transverse, from one parietal protuberance to the other,
3 1-2 inches.

15*

174 THE SUPERIOR EXTREMITIES.

cartilages, viz. : The body, not perfectly ossified ; and a bone on
each side of it, of a form almost rectangular, on which the oblique
processes are very distinguishable, and the transverse processes
may be ascertained. These bones are so applied to the body,
as to include a triangular space for the vertebral cavity. The
ends of the longest portions are nearly in contact behind ; but
the spinous process is not formed. The atlas is cartilaginous in
front, and has only the two late?al portions ossified. The verte-
bra dentata consists of four pieces ; for, in addition to the three
pieces common to the other vertebrae, the processus dentatus is a
distinct portion.

The false vertebra, of which the sacrum consists, are each
formed of three bones as the true vertebras.

The bones of the os coccygis are cartilaginous, except the
first, which is partly ossified.

The ribs are almost perfect at birth : their heads and tuber-
cles covered with cartilage. The necessity of their motion in
respiration, immediately after birth, explains this difference be
tween them, and most of the other bones of the foetus.

The sternum consists of several small bones, surrounded by
flat cartilages. Ossification goes on in these cartilages from
various points ; and the distinct bones finally unite into the three
pieces of which the sternum is finally composed.

The ossa innominata, on each side, are formed of three dis-
tinct pieces, united at the acetabulum.

The spine of the os ilium is cartilaginous ; and the lower part
of the bone is not completely ossified.

The back part of the os ischium is ossified ; but the portion
which forms the acetabulum, the tuber, and the crus, is cartila-
ginous.

The upper part of the os pubis, and that portion which forms
the symphysis, are ossified. The crus, like that of the ischium,
is cartilaginous.

Of the Superior Extremities.

Each superior extremity consists of the SHOULDER, the ARM,
the FOREARM, and the HAND.

THE CLAVICLE. 175

The shoulder is composed of the clavicle and scapula. It has
been supposed by some persons that the two last mentioned
bones belong properly to the thorax ; but upon examining the
motions of the upper extremity, it will appear that they fdrm an
essential part of it : and it is equally evident that they do not
contribute to the perfection of the thorax ; they are, therefore,
considered as a part of the upper extremity.

The Clavicle^

Is the long crooked bone resembling the italic /, which is
placed almost horizontally between the upper lateral part of the
sternum and the acromion, or most prominent process of the
scapula which it keeps off from the trunk of the body.

The clavicle, as well as other long bones, is larger at its two
ends than in the middle. The end next to the sternum is trian-
gular ; the angle behind is considerably protruded, to form a
sharp ridge, to which the transverse ligament, extended from one
clavicle to the other, is fixed. The side opposite to this is some-
what rounded. The middle of this protuberant end is irregularly
hollowed, as well as the cavity in the sternum for receiving it :
but, in a recent subject, the irregular concavities of both are
supplied by a movable cartilage ; which is not only much more
closely connected every where, by ligaments, to the circumference
of the articulation, than those of the lower jaw are, but it grows
to the two bones at both its internal and external end ; its sub-
stance at the external end being soft, but very strong, and
resembling the intervertebral cartilages.

From its internal end, the clavicle, for about two-fifths of its
length is bended obliquely forwards. On the upper and front
part of this curvature a small ridge is seen, with a plane rough
surface before it ; whence the sterno-hyoideus and sterno-mas-
toideus muscles have in part their origin. Near the lower angle,
a small plane surface is often to be remarked, where the first
rib and this bone are contiguous, and are connected by a firm
ligament. From this a rough plane surface is extended outwards,
where the pectoral muscle has part of its origin. Behind, the
bone is made flat and rough by the insertion of the larger

176 THE CLAVICLE.

share of the subclavian muscle. The clavicle is then curved
backwards, and at first is round ; but it soon after becomes broad
and thin ; which shape it retains to its external end. Along the
external concavity a rough sinuosity runs ; from which some part
of the deltoid muscle takes its rise : opposite to this, on the con-
vex edge, a scabrous ridge gives insertion to a share of the
trapezius muscle. The upper surface of the clavicle is here flat ;
but the lower is hollow, for lodging the beginning of the musculis
subclavius ; and towards its back part a tubercle rises ; to which,
and to a roughness near it, the strong, short, thick ligament,
connecting this bone to the coracoid process of the scapula, is
fixed.

The external end of this bone is oblong horizontally, smooth,
sloping at the posterior side, and tipped in a recent subject with
a cartilage, for its articulation with the acromion scapulae.
Round this the bone is spongy, for the firmer connexion of the
ligaments.

The surfaces of contact with this bone, and the scapula are
remarkably small, and flat also.

The medullary arteries, having their direction obliquely out-
wards, enter the clavicles by one or more small passages in the
middle of their back part.

The substance of this bone is the same as that of the other
round long bones.

The ligaments which surround the articulation of this bone
with the sternum, are so short snd strong, that little motion can
be allowed any way ; and the strong ligament that is stretched
across the upper forcula of the sternum, from the posterior
prominent angle of the one clavicle to the same place of the
other clavicle, serves to keep each of these bones more firmly
in its place. By the assistance, however, of the movable inter-
vening cartilage, the clavicle can move at this articulation, so
that the external extremity may be elevated or depressed, and
moved backwards and forwards. The whole bone may be
moved so as to describe a cone ; of which the end at the sternum
is the apex.

The movements of the scapula and arm are the objects of

THE SCAPULA. 177

these motions of the clavicle ; and the general use of the bone
is to regulate the motions of these parts.

From the situation, figure, and use of the clavicles, it is evident
that they are much exposed to fractures ; that their broken
parts must generally pass each other, and that they will be kept
in their places with difficulty.

The Scapula,

Or shoulder-Hade , is the triangular bone situated on the upper
and back part of the thorax. The back part of the scapula has
Fig. 40.* nothing but the thin ends of the

ser/atus anticus major, and sub-
scapularis muscles between it
and the ribs: but as this bone
advances forwards, its distance
from the ribs increases. The
longest side of this bone is near-
est the spine, and has an oblique
position as respects it. The up-
per or shortest side, called the
superior costa of the scapula, is
nearly horizontal, and parallel
with the second rib. The lower
.side, which is named the inferior
costa, is extended obliquely from
the third to the eighth rib. The
situation of this bone, here described, is, as when people are sit-
ting or standing, in a state of inactivity, and allowing the mem-
bers to remain in the most natural easy posture. The inferior
angle of the scapula is very acute ; the upper one is near to a

* A posterior view of the scapula. 1. The supra-spinous fossa. 2. The infra-
spinous fossa. 3. The superior border. 4. The supra-scapular notch. 5. The
anterior or inferior border. 6. The head of the scapula and glenoid cavity. 7.
The inferior angle. 8. The neck of the scapula, the ridge opposite the number
gives origin to the long head of the triceps. 9. The posterior border or base of
the scapula. 10. The spine. 11. The triangular smooth surface, over which
the tendon of the trapezius glides. 12. The acromion process. 13. One of the
nutritious foramina. 14. The coracoid process.

178 THE SCAPULA.

right angle ; and what is called the anterior does not deserve
the name, for the two sides do not meet to form an angle. The
body of this bone is concave towards the ribs, and convex
behind, where it has the name of dorsum. Three processes are
generally reckoned to proceed from the scapula. The first is the
large spine that rises from its convex surface behind, and divides
it unequally. The second process stands out from the forepart
of the upper side; and, from its imaginary resemblance to a
crow's beak, is named coracoides. The third process is the
whole thick bulbous forepart of the bone.

Into the oblique space the musculis patientia (levator scapul<z)
is inserted. At the root of the spine, on the, back part of the
base, a triangular flat surface is formed by the pressure of the
lower fibres of the trapezius. Below this, the edge of the
scapula is scabrous and rough, for the insertion of the serratus
major anticus and rhomboid muscles.

The back part of the inferior angle is made smooth by the
latissimus dorsi passing over it. The muscle also alters the
direction of the inferior costa some way forwards from this angle :
and so far it is flattened behind by the origin of the teres major.
As the inferior costa advances forward, it is of considerable
thickness, is slightly hollowed, and made smooth behind, by the
teres minor ; while it has a fossa formed into it below, by part
of the subscapularis ; and between the two, a ridge with a small
depression appears, where the extensor longus cubiti has its
origin.

The superior costa is very thin ; and near its forepart there
is a semi-lunar notch, from one end of which to the other, a
ligament is stretched ; and sometimes the bone is continued to
form one, or sometimes two holes, for the passage of the scapular
blood-vessels and nerves. Immediately behind this semilunar
cavity, the coraco-hyoideus muscle has its rise. From the notch,
to the termination of the fossa for the teres minor, the scapula
is narrower than any where else, and supports the third process.
This part has the name of cervix.

The whole dorsum of the scapula is always said to be con-
vex ; but, by reason of the raised edges that surround it, it is

THE SCAPULA. 179

divided into two cavities by the spine, which is stretched from
behind forwards, much nearer to the superior than to the inferior
costa. The cavity above the spine is really concave^where
the supra-spinatus muscle is lodged ; while the surface of this
bone below the spine, on which the infra-spinatus muscle is
placed, is convex, except a fossa that runs at the side of
the inferior costa.

The internal or anterior surface of this bone is hollow, except
in the part above the spine, which is convex. The subscapu-
laris muscle is extended over this surface, where it forms
several ridges and intermediate depressions, commonly mis-
taken for prints of the ribs : they point out the interstices of
the bundles of fibres of which the subscapularis muscle is
composed.

The spine rises small at the base of the scapula, and becomes
higher and broader as it advances forwards. On the sides it is
unequally hollowed and crooked, by the action of the adjacent
muscles. Its ridge is divided into two rough, flat surfaces : into
the upper one the trapezius muscle is inserted ; and the lower
one has part of the deltoid fixed to it. The end of the spine,
called acromion, or top of the shoulder, is broad and flat, and is,
sometimes, only joined to the spine by a cartilage. The anterior
edge of the acromion is flat, smooth, and covered with a cartilage,
for its articulation with the external end of the clavicle ; and it is
hollowed below, to allow a passage to the infra and supra-spinati
muscles, and free motion to the os humeri.

The coracoid process is crooked, with its point inclining for-
wards ; so that a hollow is left at the lower side of its root for
the passage of the subscapcularis muscle. The end of this pro-
cess is marked with three plane surfaces. Into the internal,
the pectoralis is inserted ; from the external, one head of the
biceps flexor cubiti rises ; and from the lower one, the coraco-
brachialis has its origin. At the upper part of the root of this
process, immediately before the semilunar cavity, a smooth
tubercle appears, where a ligament from the clavicle is fixed.
From the whole of the external side of this coracoid apophysis

180 THE SCAPULA.

a broad ligament goes out, which becomes narrower where it is
fixed to the acromion.

From the cervix scapulae the third process is produced.
The forepart of this is formed into a glenoid cavity, which is
of the shape of the longitudinal section of an egg, being broad
below and narrow above. Between the margin of this cavity
and the forepart of the root of the spine, a large sinuosity is
left for the transmission of the supra and infra-spinati muscles ;
and on the upper part of this margin we may remark a smooth
surface, where the second head of the biceps flexor cubiti has
its origin. The root of the margin is rough all around, for the
firmer adhesion of the capsular ligament of the articulation, and
of the cartilage ; the latter is thick on the margin, but becomes
very thin as it is continued towards the middle of the cavity,
which it lines all over.

The medullary vessels enter the scapula near the base of the
spine.

The substance of the scapula, as in all other broad flat
bones, is cellular, but of an unequal thickness : for the neck and
third process are thick and strong ; the inferior costa, spine, and
coracoid process, are of a middle thickness ; and the body is so
pressed by the muscles, as to become thin and transparent.

The scapula and clavicle are joined by plane surfaces, tipped
with cartilage ; by which neither bone is allowed any consider-
able motion, being tightly tied down by the common capsujar
ligament, and by a very strong one which proceeds from the
coracoid process ; but divides into two before it is fixed into
the clavicle, with such a direction as can either allow this
bone to have a small rotation, in which its posterior edge turns
more backwards, while the anterior one rises farther forwards ;
or it can yield to the forepart of the scapula moving down-
wards, while the back part of it is drawn upwards: in both
which cases, the oblong, smooth articulated surfaces of the
clavicle and scapula are not in the same plane, but stand a
little transversely, or across each other, and thereby preserve
this joint from luxations, to which it would be subject if either of
A/^*rt^r~

THE OS HUMERI. 181

the bones were to move on the other perpendicularly up and
down, without any rotation. Sometimes a movable ligamentous
cartilage is found in this joint ; and sometimes such a cartilage
is only interposed at the anterior half of it ; and in some old
subjects a sesamoid bone has been found here.

The scapula is connected to the head, os hyoides, vertebrae,
ribSj^and arm bone, by muscles that have one end fastened to
these parts, and the other to the scapula, which can move it
upwards, downwards, backwards, or forwards : by the quick
succession of these motions, its whole body is carried in a
circle. But being also often moved, as upon an axis perpen-
dicular to its plane, its circumference turns in a circle whose
centre this axis is. Whichever of these motions it performs,
it always carries the outer end of the clavicle and the arm
along with it. The glenoid cavity of this bone receives the os
humeri, which plays in it, as will be more fully explained here-
afterT

The use of the scapula, is, to serve as a fulcrum to the arm ;
and by altering its position on different occasions, to allow always
to the head of the os humeri a socket to move in properly
situated ; and thereby to assist and to enlarge greatly the motions
of the superior extremity, and to afford the muscles which rise
from it more advantageous actions, by altering their directions
with respect to the bone which they are to move. This bone
also serves to defend the back part of the thorax, and is often
employed to sustain weights, or to resist forces too great for the
arm to bear.

Os Humeri, or Arm Bone. »

The arm has only one bone, best known by the Latin name
of os humeri ; which is long, round, and nearly straight.

The upper end of this bone consists of ' a large round
smooth head, which forms the segment of a sphere, whose
axis is not in a straight line with the axis of the bone, but
stands obliquely backwards from it. The extent of the head
is distinguished by a circular fossa surrounding its base, where
16

182

THE OS HUMERI.

Fig. 41.* the head is united to the bone, and the capsular
ligament of the joint is fixed. Below the fore-
part of its base, two tubercles stand out : the
smaller one, which is situated most to the inside,
has the tendon of the subscapularis muscle in-
serted into it. The larger more external pro-
tuberance is divided, at its upper part, into
three smooth plane surfaces : into the anterior
of which, the musculus supra-spinatus ; into
the middle or largest, the infra-spinatus ; and
into the one behind, the teres minor, is inserted.
Between these two tubercles, exactly in the
forepart of the bone, a deep long groove is
formed, for lodging the tendinous head of the
biceps flexor cubiti ; which, after passing, in a
manner peculiar to itself, through the cavity of
the articulation, is tied down, by a tendinous
sheath extended across the groove ; in which,
and in the neighboring tubercles, are several
remarkable holes, which are penetrated by the tendinous and
ligamentous fibres, and by vessels. On each side of this
groove, as it descends in the os humeri, a rough ridge, gently
flattened in the middle, runs from the roots of the tubercles.
The tendon of the pectoral muscle is fixed into the anterior of
these ridges, and the latissimus dorsi and teres major are
inserted into the internal one. A little behind the lower end
of this last, another rough ridge may be observed, where the
coraco-brachialis is inserted. From the back part of the root
of the largest tubercle, a ridge also is continued; from which
the extensor brevis cubiti arises. This bone is flattened on the

* The humerus of the right side ; its anterior surface. 1. The shaft of the
bone. 2. The head. 3. The anatomical neck. 4. The greater tuberosity. 5.
The lesser tuberosity. 6. The bicipital groove. 7. The anterior bicipital ridge.
8. The posterior bicipital ridge. 9. The rough surface into which the deltoid is
inserted. 10. The nutritious foramen. 11. The rounded protuberance of the
articular surface. 12. The pulley-like surface. 13. The external condyle. 14.
The internal condyle. 15. The external conclyloid ridge. 16. The internal
condyloid ridge. 17. The fossa for the coronoid process of the ulna.

THE OS HUMERI. 183

inside, about its middle, by the belly of the biceps flexor cubiti.
In the middle of this plane surface, the entry of the medullary
artery is seen slanting obliquely downwards. At the fireside
of this plane, the bone rises in a sort of ridge, which is rough,
and often has a great many small holes in it, where the strong
deltoid muscle is inserted ; on each side of which the bone is
smooth and flat, where the brachialis internus rises. The
exterior of these two flat surfaces is the largest : behind it is a
superficial spiral channel, formed by the muscular nerve, and the
vessels that accompany it ; it runs from behind forwards and
downwards.

The body of the os humeri is flattened behind by the exten-
sors of the forearm.

Near the lower end of this bone, a large sharp ridge is
extended on its outside ; from which the musculus supinator
radii longus, and the longest head of the extensor carpi radi-
alis, arise. Opposite to this there is another small ridge to
which the aponeurotic tendon, that gives origin to the fibres of
the internal and external brachial muscles, is fixed ; and from
a little depression on the foreside of it, the pronator radii teres
arises.

The body of the os humeri becomes gradually broader
towards the lower end, where it has several processes ; at the
roots of which there is a cavity before, and one behind, called
sigmoid. The anterior is divide'd by a ridge into two ; the
external, which is the least, receives the end of the radius ; and
the internal receives the coronoid process of the ulna, in the
flexions of the forearm ; while the posterior deep triangular
cavity lodges the olecranon in the extensions of that limb.
The bone between these two cavities is pressed so thin by the
processes of the ulna, as to appear transparent in many sub-
jects. The sides of the posterior cavity are stretched out into
two processes, one on each side. These are called condyles ;
from each of which a strong ligament goes out to the bones of
the forearm. The external condyle, which has an oblique
direction forwards with respect to the internal, when the arm

184 THE OS HUMERt.

is in the most natural posture, is equally broad, and has an
obtuse smooth head rising from it forwards. From the rough
part of the condyle, several muscles arise ; and on the smooth
head the upper end of the radius plays. The internal condyle
is more pointed and protuberant than the external, to give origin
to the flexor muscles of the wrist and hands, &c. Between
the two condyles, is the trochle^i, or pulley ; which consists of
two lateral protuberances and a middle cavity that are smooth,
and covered with cartilage. When the forearm is extended, the
tendon of the internal brachialis muscle is lodged in the forepart
of the cavity of this pulley. The external protuberance, which
is less than the other, has a sharp edge behind : but forwards,
this ridge is obtuse, and only separated from the little head,
already described, by a small fossa, in which the adjoining edges
of the ulna and radius move. The internal protuberance of the
pulley is largest and highest ; and therefore, in the motions of
the ulna upon it, that bone would be inclined outwards, were
it not supported by the radius on that side. Between this in-
ternal protuberance and condyle, a sinuosity may be remarked,
where the ulnar nerve passes.

The substance and the internal structure of the os humeri
are the same, and disposed in the same way, as in the other long
bones.

The round head, at the upper end of this bone, is articulated
with the glenoid cavity of the scapula ; which being superficial
and having long ligaments, allows the arm a free and extensive
motion. These ligaments are, however, considerably strong.
For, besides the common capsular ligament, the tendons of the
muscles perform the office, and have been described under the
name of ligaments. Then the acromion and coracoid process,*
with the strong broad ligaments stretched between them, secure
the articulation above ; where the greatest and most frequent
force is applied, to thrust the head of the bone out of its place.
It is true, that there is not near so strong a defence in the lower
part of the articulation ; but, in the ordinary postures of the
arm, that is, so long as it is an acute angle with the trunk of

BONES OF THE FOREARM. 185

the body, there cannot be any force applied at this place to
occasion a luxation, since the joint is protected so well
above.

The motions which the arm enjoys by this articulation, are
to every side ; and, by the succession of these different motions,
a circle may be described. Besides which, the bone performs
a small rotation round its own axis ; but, when the axis of the
bone is the centre of motion, the movements are very different
from those which take place when the axis of its head is the
centre; for the axis of the head forms a very large angle with
the axis of the body of the bone. Thus, when the arm swings
backwards and forwards, the axis of the head is the centre of
motion : but when the elbow is bent, and the forearm forms a
right angle with the os humeri, the motion which applies the
forearm to the thorax, or removes it, is a rotation of this bone
on its axis.

Though the motions of the arm seem to be very extensive,
yet the larger share of them depends on the motions of the
scapula ; for the surface of the glenoid cavity is directed
upwards or downwards, and, to a certain degree, backwards
or forwards, to support the head of the os humeri. This is
exemplified when we press the hand against a body which is
before, or above, or to one side of us.

The lower end of the os humeri is articulated to the bones of
the forearm, and carries them with it in all its motions ; but
serves as a base, on which they perform the motions peculiar to
themselves; as will shortly be described.

The Forearm

Consists of two bones, one of which is called ulna, from its
being used as a measure ; and the other radius, from the sup-
posed resemblance to the spoke of a wheel. ,,

These bones are concerned in very different operations. The
ulna forms the elbow joint with the os humeri ; the radius is
the movable basis of the hand.
16*

186 THE ULNA.

Vina.

The length of this bone is equal to the forearm, of which
it is a part. It is thickest above, and gradually diminishes
until near its lower end. The body of the bone is nearly
Fig. 42.* triangular in form. At the upper extremity
of the ulna, on its anterior surface, is a
semicircular notch. The end of the bone
which forms the posterior part of this
notch is denominated olecranon. The an-
terior part of the notch is formed by a
process called coronoid. This notch ap-
plies to the pulley-like surface on the internal
side of the lower extremity of the os humeri,
to form the articulation of the elbow. In
the middle of the concave surface is a ridge,
in consequence of which, a srqall rocking
motion is performed by the ulna. The
external surface of the olecranon is rough,
and strongly marked. The extensor mus-
cle of the forearm is inserted into the
end of it, and below this is a flat surface
on which we lean. On the outside of
the coronoid process is a semilunated smooth cavity, lined
with cartilage; in which, and in a ligament extended
from the one to the other end of this cavity, the round
head of the radius plays. Immediately below it, a rough
hollow gives lodging to the mucilaginous glands. Below the
root of the coronoid process, this bone is scabrous and unequal,
where the brachialis interims is inserted. On the outside of

* The two bones of the forearm seen from the front. 1. The shaft of the ulna.
2. The greater sigmoid notch. 3. The lesser sigmoid notch, with which the
head of the radius is articulated. 4. The olecranon process. 5. The coronoid
process. 6. The nutritious foramen. 7. The sharp ridges upon the two bones
to which the interosseous membrane is attached. 8. The rounded head at the
lower extremity of the ulna.V9. The styloid process. 10. The shaft of the
radius. 11. Its head surrounded by the smooth border for articulation with the
orbicular ligament. 12. The neck of the radius. 13. Its tuberosity. 14. The
oblique line. 15. The lower extremity of the bone. 16. Its styloid process.

THE ULNA. 187

that, we observe a smooth concavity, where the beginning of
the flexor digitorum profundus sprouts out.

The external angle of the triangular part of the ulnajs very-
sharp, where the ligament that connects the two bones is fixed ;
the sides which make this angle are flat and rough, by the ac-
tion and adhesion of the many muscles which are situated
here. At the distance of one-third of the length of the ulna
from the top, in its forepart, the passage of the medullary ves-
sels may be seen slanting upwards. The internal side of the
bone is smooth, somewhat convex, and the angles at each edge
of it are blunted by the pressure of the muscles equally disposed
about them. '

As this bone descends, it becomes gradually smaller ; so that
its lower end terminates in a little head, standing on a small
neck : towards the inner and back part of which last, an oblique
ridge runs, that gives rise to the pronator radii quadratus. The
head is sometimes cylindrical, smooth, and covered with a car-
tilage on its external side, to be received into the semilunar
cavity of the radius ; which a styloid process rises from its in-
side, to which is fixed a strong ligament that is extended to the
os cuneiforme and pisiforme of the wrist. At the root of the
process, the end of the bone is smooth, and covered with a car-
tilage. Between it and the bones of the wrist, a doubly con-
cave movable cartilage is interposed ; which is a continuation
of the cartilage that covers the lower end of the radius, and is
connected loosely to the root of the styloid process, and to the
rough cavity there ; in which mucilaginous glands* are
lodged.

The ulna is principally concerned in the articulation with the
os humeri, and forms a hinge-like joint, which allows extension
nearly to a straight line, and flexion to an acute angle. By the
sloping of the pulley-like surface, the lower part of the arm is
turned outwards in the extension, and inwards in the flexion ;
which greatly facilitates the motion of the hand towards the
head.

* All these so called glands are m.ere masses of adipose matter, supposed,
though wrongly by Havers to be the glands which secrete the synovia. — P.

188 RADIUS.

Radius.

Before the radius is described, it is necessary to observe that the lower end of
this bone occasionally revolves half round the lower end of the ulna, and the
hand with it. The relative situation of these parts is, therefore, different in
different positions of the hand. In the following description, the palm of the
hand is supposed to present forwards, and the thumb outwards j in which case,
the two bones of the forearm will be parallel to each other.

•
The radius is situated on the outside of the forearm, and is

rather shorter than the ulna. Its extremities are the reverse of
those of the ulna in their proportionate size ; and the body is
not triangular, although it approaches towards that form. Its
upper end is formed into a cylindrical head, which is hollowed
on the top for an articulation with the tubercle at the side of
the pulley of the os hurneri ; and the half cylindrical circum-
ference next to the ulna is smooth, and covered with a carti-
lage, in order to be received into the sernilunated cavity of that
bone. Below the head, the radius is much smaller ; and, there-
fore, this part is named its cervix. >( At the internal root of this
neck is a flat tubercle, into the inner part of which the biceps
flexor cubiti is inserted. From this a ridge runs downwards and
outwards where thesupinator radii brevis is inserted; and a little
below, and behind this ridge, there is a rough scabrous surface,
where the pronator radii teres is fixed.

The body of the radius is not straight, but curved externally
the greater part of its length. Its external surface is rounded ;
tne anterior and posterior surfaces are flattened ; and between
them is a sharp spine, to which the strong ligament extended
between the two bones of the forearm is fixed. On the ante-
rior surface, at a distance from its head, nearly equal to one-
third the length of the bone, is the orifice of the canal for
the medullary vessels, which has a direction obliquely up-
wards.

Towards the lower end the radius becomes broader and
flatter, especially on its forepart, where the pronator quadratus
muscle is situated. Its back part, at this end, has a flat strong
ridge in the middle, and fossae on each side. In a small groove,

' •

RADIUS. 189

immediately on the inside of the ridge, the tendon of the
extensor of the last joint of the thumb plays. In a large one,
inside of this, the tendons of the indicator, and of the common
extensor muscles of the fingers pass. On the outside *6f the
ridge there is a broad depression, which seems again subdivided,
where the two tendons of the extensor carpi radialis are lodged.
The external side of this end of the radius is also hollowed
by the extensors of the first and second joints of the thumb.
The ridges at the sides of the grooves, in which the ten-
dons play, have an annular ligament fixed to them, by which
the several sheaths for the tendons are formed. The forepart
of this end of the radius is also depressed, where the flexors of
the fingers and flexor carpi radialis pass. The internal side is
formed into a semilunated smooth cavity, lined with a cartilage,
for receiving the lower end of the ulna. The lowest part of
the radius is formed into an oblong cavity ; in the middle of
which is a small transverse rising, gently hollowed, for lodging
mucilaginous glands ; while the rising itself is insinuated into
the conjunction of the two bones of the wrist that are received
into the cavity. The external side of this articulation is defended
by a remarkable process of the radius, from which a ligament
passes to the wrist ; and this structure resembles that of the
styloid process of the ulna with its ligament.

The ends of both the- bones of the forearm being thicker than
the middle, and the radius being curved, there is a considerable
distance between the bodies of these bones ; in the larger part of
which a strong, tendinous, but tliin ligament, is extended, to give
a sufficient surface for the origin of the numerous fibres of the
muscles situated here, that are so much sunk between the bones
as to be protected from injuries, to which they would otherwise
be exposed. But this ligament is wanting near the upper end ~
of the forearm, where the supinator radii brevis and flexor digi-
torum profundus, are immediately connected.

As the head of the radius receives the tubercle of the os
humeri, it is not only bended and extended along with the ulna,
but may be moved almost half round its axis ; and that this

190 THE HAND.

motion round its axis may be sufficiently large, the ligament
of the articulation is extended farther down than ordinary, on
the neck of this bone, before it is connected to it ; and it is
very thin at its upper and lower part, but makes a firm ring in
the middle. This bone is also joined to the ulna by a double
articulation : for above, a tubercle of the radius plays in a socket
of the ulna ; whilst below, the radius gives the socket, and the
ulna the tubercle. But then the motion performed at the two
ends is very different : for, at the upper end, the radius does little
more than turn round its axis ; while, at the lower end, it moves
nearly half round the cylindrical end of the ulna ; and, as the
hand is articulated and firmly connected here with the radius,
they must move together. When the palm is turned uppermost,
the radius is said to perform supination : when the back of the
hand is above, it is said to be prone. But then the quickness
and large extent of these two motions are assisted by the ulna,
which, as was before observed, can move wilh a kind of small
rotation on the sloping sides of the pulley. This rocking motion,
though very inconsiderable in the elbow joint itself, is conspicu-
ous at the lower end of such a long bone ; and the strong
ligament connecting this lower end to the carpus, makes the
hand more readily obey these motions.

The Hand.

The hand comprehends the whole structure, from the end of
the radius to the points of the fingers. Its back part is convex,
for greater firmness and strength ; and it is concave before, for
containing more surely and conveniently such bodies as we
take hold of. One half of the hand has an obscure motion in
comparison of what the other has ; it serves as a base to the
movable half, which can be extended back very little farther than
to a straight line with the forearm, but can be considerably bent
forwards.

The hand consists of the carpus or wrist ; metacarpus, or
part adjoining the wrist ; and the fingers, a*mong which the
thumb is reckoned.

CARPUS. 191

Carpus.

No part of the skeleton is more complex than the carpus. The following descrip-
tion will, therefore, be of little use to a young student, unless the bones are
before him when he is reading it. Great advantage will be derived from
examining two sets of carpal bones: each set belonging to the same side.
In one of these sets the bones should be connected by their natural ligaments ;
but the two rows separated from each other. The bones of the other set
should be accurately cleaned; so that their forms and surfaces may be examined.

The carpus is composed of eight small bones, arranged in two
rows ; one of which rows is attached to the bones of the fore-
arm, and the other to the body of the hand. <@

These bones are named from their figure and shall be
mentioned in the order in which they occur, beginning with the
row next to the forearm ; and with the external bone in each
row.

They are, Os Scaphoides, Lunare, Cuneiforme, Pisiforme,
forming the upper row ; Os Trapezium, Trapezoides, Magnum,
and Unciforme, forming the lower row.

First Row.

Os scaphoides is the largest of the eight, excepting one. It
is convex above, concave and oblong below ; from which small
resemblance to a boat, it has got its name. Its smooth convex
surface is divided by a rough middle fossa, which runs obliquely
across it. The upper largest division is articulated with the
radius. The common ligament of the joint of the wrist is fixed
into the fossa ; and the lower division is joined to the trapezium
and trapezoides. The concavity receives more than half of the
round head of the os magnum. The internal side of this hollow
is formed into a semilunar plane to be articulated with the
following bone. The external, posterior, and anterior edges are
rough, for fixing the ligaments that connect it to the surrounding
bones.

Os lunare has a smooth convex upper surface, by which it is
articulated with the radius. The external side, which gives
the name to the bone, is in the form of a crescent, nad is
joined with the scaphoid : the lower surface is hollow, for
receiving part of the head of the os magnum. On the inside

192

CARPUS.

Fig. 43.* of this cavity is another smooth,

but narrow, oblong sinuosity, for
receiving the upper end of the
unciforme : and on the inside of this
a small convexity is found, for its
connexion with the os cuneiforme.
Between the great convexity above,
and * the first deep inferior cavity,
there is a rough fossa, in which the
circular ligament of the joint of the
wrist is fixed.

Os cuneiforme is broader above
and towards the back of the hand,
than it is below and forwards ; which gives it the resem-
blance of a wedge. The superior slightly convex surface is
included in the joint of the wrist, being opposed to the lower
end of the ulna. Below this the cuneiforme bone has a rough
fossa, wherein the ligament of the articulation of the wrist is
fixed. On the external side of this bone, where it is contiguous
to the os lunare, it is smooth, and slightly concave. Its lower
surface, where" it is contiguous to the os unciforme, is oblong,
somewhat spiral, and concave. Near the middle of its anterior
surface, a circular plane appears, where the os pisiforme is
sustained.

Os pisiforme is almost spherical, except one circular plane,
or slightly hollowed surface, which is covered with cartilage for
its motion on the cuneiforme bone, from which its whole

* A diagram showing the dorsal surface of the bones of the carpus, with
their articulations. — The right hand. R. The lower end of the radius. U. The
lower extremity of the ulna. F. The inter-articular fibro- cartilage attached to
the styloid process of the ulna, and to the margin of the articular surface of the
radius. S. The scaphoid bone : the numeral (5) indicates the number of bones
with which it articulates. L. The semilunare articulating with five bones. C.
The cuneiforme, articulating with three bones. P. The pisiforme, articulating
with the cuneiforme only. T. The first bone of the second row — the trapezium,
articulating with four bones. T. The second bone — the trapezoides, articulating
also with four bones. M. The os magnum, articulating with seven. U. The
unciforme, articulating with five. The numerals, 1, 3, 1,2, 1, on the metacarpal
bones, refer to the number of their articulations with the carpal bones.

CARPUS. 193

rough body is prominent forwards into the palm ; having the
tendon of the flexor carpi ulnaris, and a ligament from the
styloid process of the ulna fixed to its tipper part ; the trans-
verse ligament of the wrist is connected to its externaFside :
ligaments extended to the unciforme bone, and to the os
metacarpi of the little finger, are attached to its lower part ;
the abductor minimi digiti has its origin from its forepart ;
and, at the external side of it, a small depression is formed for
the psssage of the ulnar nerve.

Second Row.

Os Trapezium has four unequal sides and angles in its back
part, from which it has got its name. Above, its surface is
smooth, slightly hollowed, and semicircular, for its conjunction
with the os scaphoides. Its internal side is an oblong concave
square, for receiving the following bone. The inferior surface
is formed into a pulley, which faces obliquely outwards and
downwards when the palm presents forward. On this pulley
the first bone of , the thumb is moved.

At the internal side of the pulley, a small oblong smooth
surface is formed by the os metacarpi indicis. The forepart
of the trapezium is prominent in the palm, and near to the in-
ternal side has a sinuosity in it, where the tendon of the flexor
carpi radialis is lodged, on the ligamentous sheath of which
the tendon of the flexor longus pollicis manus plays : near
this the bone is scabrous, where the transverse ligament of
the wrist is connected, the abductor and the flexor brevis
pollicis have their origin, and ligaments go out to the first of
the thumb.

Os trapezoides, so called from the irregular quadrangular
figure of its back part, is the smallest bone of the wrist, except
the pisiforme. The figure of it is an irregular cube. It has a
small hollow surface above, by which it joins the scaphoides ;
a long convex one externally, where it is contiguous to the
trapezium ; a small internal concavity, for its conjunction
with the os magnum ; and an inferior convex surface, the
edges of which are, however, so raised before and behind, that
17

194 CARPUS.

a sort of pulley is formed, where it sustains the os metacarpi
indicis.

Os magnum, so called because it is the largest bone of the
carpus, is oblong, having four quadrangular sides, with a round
upper end, and a triangular plane one below. The round head
is divided by a small rising, opposite to the connexion of the
os scaphoides and lunare, which together form the cavity for
receiving it. On the outside a short plane surface joins the os
magnum to the trapezoides. On the inside is a long narrow
concave surface where it is contiguous to the os unciforme.
The lower end, which sustains the metacarpal bone of the
middle finger, is triangular, slightly hollowed, and farther
advanced on the external side than on the internal, having a
considerable oblong depression made on the advanced outside
by the metacarpal bone of the fore-finger ; and generally there
is a small mark of the os metacarpi digiti annularis on its inter-
nal side.

Os unciforme has got its name from a thin broad process
that stands out from it forwards into the palr% and is hollow,
for affording passage to the tendons of the flexors of the fingers.
To this process, also, the transverse ligament is fixed that binds
down, and defends these tendons ; and. the flexor and abductor
muscles of the little finger have part of their origin from it.
The upper plane surface is small, convex, and joined with
the os lunare : the external side is long and slightly convex,
adapted to the contiguous os magnum. The internal surface is
oblique, and irregularly convex, to be articulated with the
cuneiforme bone. The lower end is divided into two concave
surfaces; the internal is joined with the metacarpal bone of
the little finger; and the external one is fitted to the metacarpal
bone of the ring finger.

The nature of the carpus will be best understood by studying
the bones placed together, in their natural order, in the two
rows.

When thus placed, they compose a structure of an oblong
form, whose greatest length extends across the wrist, and forms
a concavity in front, while it is convex posteriorly.

CARPUS.

195

Fig. 44.* Two bones of the first row, viz., the

scaphoides and lunare, form an oblong
convex surface, which has a transverse
position with respect to the arm, and
applies to the concave surface at the
end of the radius. These surfaces are
particularly calculated for flexion and
extension, and also for a considerable
motion to each side ; and by a suc-
cession of these flexures, in different
directions, the hand performs a cir-
cular motion, although it cannot
perform at this joint a rotation, or
revolution, on the axis of the car-
pus.

The under surface of the bones has a deep concavity, which
is composed by the scaphoides, lunare and cuneiforme, and
receives a prominence of the second row. It also presents a
convex surface, formed by the scaphoides, which is received
by the second row.

The upper surface of the second row, which is concerned in
this articulation, is very irregular ; it has a head formed by the
magnum and unciforme, which penetrates deeply into the
cavity of the first row. On the outside of this head the tra-
pezium and trapezoides form a surface, which receives the
projecting part of the scaphoides ; so that the first row receives,
and is received by the second, and the two surfaces are well
calculated for moving, to a certain extent, in the way of flexion
and extension, upon each other. I

The lower surface of the second row, which is connected to

* The hand viewed upon its anterior or palmer aspect. 1. The scaphoid bone.
2. The semilunare. 3. The cuneiforme. 4. The pisiforme. 5. The trapezium.
6. The groove in the trapezium that lodges the tendon of the flexor carpi
radialis. 7. The trapezoides. 8. The os magnum. 9. The unciforme. 10, 10.
The five metacarpal bones. 11, 11. The first row of phalanges. 12, 12. The
second row. 13, 13. The third row, or ungual phalanges. 14. The first phalanx
&£ the thumb. 15. The second and last phalanx of the thumb.

196 THE METACARPUS.

the metacarpal bones, appears like the side of an arch, which
is partly induced by the wedge-like form of the two bones in
the centre ; viz., the trapezoides, and the magnum. When
the hand hangs by the side, and the palm is forward, all of this
surface presents downwards, except that portion of it which is
formed by the trapezium. This bone is placed obliquely
between the two rows, and its gurface for supporting the thumb
presents obliquely downwards and outwards.

The trapezoides supports the fore-finger, the magnum the
middle finger.

The scaphoides and the trapezium are very prominent at
the external side of the anterior concave surface of the car-
pus ; and the unciforme process, and the os pisiforme on the
internal.

The Metacarpus,

Consists of four bones, which sustain the finger. Each bone
is long and round, with its ends larger than its body. The
upper end, which some call the base, is flat and oblong, in-
clining somewhat to the wedge-like form, without any con-
siderable head or cavity ; but it is, however, somewhat
hollowed for the articulation with the carpus. It is made flat
and smooth on the sides where these bones are contiguous to
each other. Their bodies are flattened on the back part,
particularly below the middle, by tendons of the extensors of
the fingers. The anterior surface of these bodies is a little
convex, especially in their middle ; along which a sharp ridge
stands out, separating the musculi interossei placed on each
side of these bones, which are there made flat and plain by
these muscles.

Their lower ends are raised into large oblong smooth heads,
whose greatest extent is forwards from the axis of the bone.
At the forepart of each side of the root of these heads, one or
two tubercles stand out, for fixing the ligaments that go from
one metacarpal bone to another, to preserve them from being
drawn asunder. Around the heads a rough ring may be

THE METACARPUS, 197

remarked, for the capsular ligaments of the first joints of the
fingers to be fixed to ; and both sides of these heads are flat, by
pressing on each other. s

The substance of the metacarpal bones is the same with that
of all long bones.

The metacarpal bones are joined above to the bones of the
carpus, and to each other by surfaces almost flat. These con-
nexions do not admit of much motion. The articulation of the
round heads, at their lower ends, with the cavities of the first
bones of the fingers, will soon be described.

The concavity on the forepart of the metacarpal bones, and
the position of their basis on the arched carpus, cause them to
form a hollow in the palm of the hand, which is often useful
to us. The spaces between them lodge muscles, and their
small motion makes them fit supporters for the fingers to play
on.

Though the ossa metacarpi so far agree, yet they may be dis-
tinguished from each other by the following marks :

The metacarpal bone of the fore-finger is generally the
longest. Its base, which is articulated with the os trapezoides,
is hollow in the middle. The small ridge on the external side
of this oblong cavity is smaller than the one opposite to it, and
is made flat on the side by the trapezium. The internal ridge
is also smooth, and flat on its ulnar side, for its conjunction
with the os magnum ; immediately below which, a semicircular
smooth flat surface shows the articulation of this to the second
metacarpal bone. The back part of this base is flattened where
the long head of the extensor carpi radialis is inserted, and its
forepart is prominent where the tendon of the flexor carpi radialis
is fixed. The tubercle at the internal root of its head is larger
than the external. Its base is so firmly fixed to the bone it is
connected with, that it has no motion.

The metacarpal bone of the middle finger is generally the
second in length ; but often it is as long as the former : some-
times it is longer ; and it frequently appears only to equal the
first by the os magnum being farther projected downwards
than any other bone of the wrist. Its base is a broad super-
17*

198 THE METACARPUS.

ficial cavity, slanting inwards ; the external posterior angle of
which is so prominent, as to have the appearance of a process.
The external side of this base is made plane in the same way
as the external side of the former bone, while its internal side
has two hollow circular surfaces, for joining the third metacarpal
bone ; and between these surfaces there is a rough fossa, for the
adhesion of a ligament, and lodging mucilaginous glands. The
extensor carpi radialis brevior is inserted into the back part of
this base. The two sides of this bone are almost equally flat-
tened ; but the ridge on the forepart of the body inclines inwards.
The tubercles at the forepart of the root of the head are equal.
The motion of this bone is very little more than that of the
former ; and therefore these two firmly resist bodies pressed
against them by the thumb or fingers, or both.

The metacarpal bone of the ring finger is shorter than the
second metacarpal bone. Its base is semicircular and convex,
for its conjunction with the os unciforme. On its external side
are two smooth convexities, and a middle fossa, adapted to the
second metacarpal bone. The internal side has a triangular
smooth concave surface to join it with the fourth one. The
anterior ridge of its body is situated more to the inside than to
the outside. The tubercles near the head are equal. The mo-
tion of this third metacarpal bone is greater than the motion of
the second.

The metacarpal bone of the little finger is the smallest and
sharpest. Its base is irregularly convex, and rises slanting
inwards. Its external side is exactly adapted to the third meta-
carpal bone. The internal has no smooth surface, because it is
not contiguous to any other bone ; but it is prorninent where
the extensor carpi ulnaris is inserted. As this metacarpal bone
is furnished with a proper moving muscle, has the plainest articu-
lation, is most loosely connected and least confined, it not only
enjoys a much larger motion than any of the rest, but draws
the third bone with it, when the palm of the hand is to be made
hollow by its advancement forwards, and by the prominence of
the thumb opposite to it.

THUMB AND FINGERS. 199

Thumb and Fingers.

The thumb and fore-fingers are each composed o£ three
bones.

The THUMB is situated obliquely in respect to the fingers ;
neither opposite directly to them, nor in the same plane
with them. All its bones are much thicker and stronger in
proportion to their length, than the bones of the fingers are ;
which is extremely necessary, as the thumb counteracts all the
fingers.

The first bone of the thumb has its base adapted to the pecu-
liar articulating surface of the trapezium : for, in viewing it from
one side to the other, it appears convex in the middle ; but,
when viewed from behind forwards, it is concave there. The
edge at the forepart of this base is extended farther than any
other part ; and round the back part of the base a rough fossa
may be seen, for the connexion of the ligaments of this joint.
The body and head of this bone are of the same shape as the
ossa metacarpi ; only that the body is shorter, the head flatter,
and tubercles at the forepart of its root larger.

The articulation of the upper end of this bone is remarkable ;
for, though it has protuberances and depressions adapted to the
double pulley of the trapezium, yet it enjoys a circular motion,
as the joints do where a round head of the one plays in the
orbicular socket of another ; it is, however, more confined, and
less expeditious, but stronger and more secure than such joints
generally are.

The second bone of the thumb has a large base formed into
an oblong cavity, whose greatest length is from one side to the
other. Round it several tubercles may be remarked, for the
insertion of ligaments. Its body is convex, or half round behind ;
but flat before, for lodging the tendon of the long flexor, of the
thumb, which is tied down by ligamentous sheaths, that are
fixed on each side to the angle at the edge of this flat surface.
The lower end of this second bone has two lateral round protu-
berances, and a middle cavity, whose greatest extent of smooth
surface is forwards and backwards.

200 FINGERS.

The articulation of the upper end of this second bone would
seem calculated for motion in all directions ; yet, on account of
the strength of its lateral ligaments, the oblong figure of the joint
itself, and mobility of the first joint, it only allows flexion and
extension ; and these are generally much confined.

The third bone of the thumb is the smallest, with a larse base,

•/ O *

whose greatest extent is from oj?e side to the other. This base
is formed into two cavities and a middle protuberance, to be
adapted to the pulley of the former bone. This bone becomes
gradually smaller, till near the lower end, where it is a little
enlarged, and has an oval scabrous edge. Its body is rounded
behind, but is flatter than in the former bone, for sustaining the
nail. It is flat and rough before, by the insertion of the flexor
longus pollicis.

The motion of this third bone is confined to flexion and
extension.

The regular arrangement of the bones of the FINGERS in three
rows, has obtained for them the name of the three phalanges.
All of them have half round convex surfaces, covered with an
aponeurosis, formed by the tendons of the extensors, lumbri-
cales, and interossei, and placed directly backwards, for their
greater strength ; and their flat concave part is forwards, for
taking hold more surely, and for lodging the tendons of the
flexor muscles. The ligaments for keeping down these tendons
are fixed to the angles that are between the convex and concave
sides.

The bones of the first phalanx of the fingers answer to the
description of the second bone of the thumb ; only that the
cavity in their base is not so oblong ; nor is their motion on the
metacarpal bones so much confined ; for they can move laterally
or circularly, the fore-finger in particular, but have no rotation,
or a very small degree of it, round their axis.

The second bone of the fingers has its base formed into two
lateral cavities, and a middle protuberance : while the lower
end has two lateral protuberances, and a middle cavity : there-
fore, it is joined at both ends in the same manner ; which none
of the bones of the thumb are.

THE THIGH. 201

The third bone differs in nothing from the description of the
third bone of the thumb, except in the general distinguishing
marks ; and, therefore, the second and third phalanx -6f the
fingers enjoy only flexion and extension.

All the difference of the phalanges of the several fingers
consists in their magnitude. The bones of the middle finger
being the longest ancf largest ; those of the fore-finger come next
to these in thickness, but not in length, for those of the ring
finger are a little longer. The little finger has the smallest
bones. This disposition is the best contrivance for holding the
largest bodies ; because the longest fingers are applied to the
middle largest periphery of such substances as are of a spherical
figure.

The Inferior Extremities.

The inferior extremities consist of the THIGH, LEG, and
FOOT.

The Thigh

Consists of one bone only ; the os femoriSj which is very
strong, and larger than any other in the skeleton. It is nearly
cylindrical in the middle, and slightly curved. The upper
extremity is a spherical head, connected to the body of the bone
by a neck. The lower extremity is much larger than the body,
and is formed into two condyles.

The upper end of this bone is not continued in a straight line
with the body of it, but the axis of it inclines obliquely inwards
and upwards, whereby the distance between these two bones, at
their upper part, is considerably increased. The head is the
greater portion of a sphere. Towards its lower internal part,
a round, rough spongy pit is observable, where the strong
ligament, commonly, but inaccurately, called the round one, is
fixed, to be extended from thence to the lower internal part of
the receiving cavity, where it is considerably broader than near
to the head of the thigh bone. The neck of the os femoris has
a great many large holes, into which the fibres of the strong

202

THE THIGH.

ligament, continued from the capsular, enter, and are thereby
firmly united to it ; and round the root of the neck, where it
rises from the bone, a rough ridge is found, where the capsular
Fig. 45.* ligament of the articulation itself is con-
nected. Below this root, a large unequal
protuberance, called trochanter major,
stands out ;. the external convex part of
which is distinguished into three different
surfaces; whereof the one on the upper and
front part is scabrous and rough, for the
insertion of the glutaeus minimus ; the supe-
rior one is smooth, and has the glutaeus
medius inserted into it ; and the one behind
is made flat and smooth, by the tendon of
the glutaeus maximus passing over it. The
upper edge of this process is sharp and
pointed at its back part, where the glutaeus
medius is fixed ; but forwards it is more
obtuse, and under it is a depression, into
which some of the muscles, which rotate
the thigh outwards, are fixed. From the
posterior prominent part of this great tro-
chanter, a rough ridge runs backwards and
downwards, into which the quadratus is
inserted. In the deep hollow, at the inter-
nal upper side of this ridge, the obturator
externus is implanted. More internally, a conical process,
called trochanter minor, rises, for the insertion of the musculus
psoas and iliacus internus ; and the pectineus is implanted into
a rough hollow, below its internal root. The muscles inserted
into these processes being the principal instruments of the

* The right femor, seen upon the anterior aspect. I. The shaft. 2. The head.
3. The neck. 4. The great trochanter. 5. The anterior intertrochanteric line.
6. The lesser trochanter. 7. The external condyle. 8. The internal condyle.
9. The tuberosity for the attachment of the external lateral ligaments. 10. The
groove for the tendon of origin of the popliteus muscle. 11. The tuberosity for
the attachment of the internal lateral ligament.

OS FEMORIS. 203

y rotary motion of the thigh, have occasioned the name of trochan-
ters to be given to these processes.

The body of the os femoris is convex on the forepart and
concave behind, which enables us to sit without leaning too
much on the posterior muscles.

On the posterior concave surface is a broad rough ridge called
lima aspera, which commences near the great trochanter, and
continues downwards, more than two-thirds of the length of
the bone, when it divides into two ridges, which descend
towards each condyle. The internal of these ridges is the most
smooth, and the space between them is nearly flat. Near the
end of each of these ridges, a small, smooth-protuberance may
often be remarked, where the two heads of the external gastroc-
nemius muscles take their rise ; and from the forepart of the
internal tubercle, a strong ligament is extended to the inside of
the tibia.

The lower end of the os femoris is larger than any other part
of it, and is formed into two great protuberances, one on each
side, which are called its condyles : between them a considerable
cavity is found, especially at the back part, in which the crural
vessels and nerves lie. The internal condyle is longer than the
external, which must happen from the oblique position of this
bone, to give less obliquity to the leg. These processes are of
an oblong form, and are placed obliquely with respect to each
other ; being in contact before and separated to a considerable
distance behind.

They form in front a smooth pulley-like surface, the external
side of which is highest, on which the patella moves.

Below, they are flat ; and posteriorly, they are regularly
convex.

Between these convex portions is a rough cavity, from which
the crucial ligament arises, to be attached to the tibia. Round
the lower end of the thigh bone, large holes are found, into
which the ligaments for the security of the joint are fixed, and
blood-vessels pass to the internal substance of the bone.

The thigh bone being articulated above with the acetabulum
of the os innominatum, which affords its round head a secure
and extensive play, can be moved to every side : but it is

204 THE LEG.

restrained in its motion outwards by the high brims of the
cavity, and by the round ligament ; for otherwise the head of
the bone would have been frequently thrust out at the breach of
the brims on the inside, which allows the thigh to move consider-
ably inwards. The body of this bone enjoys little or no
rotary motion, though the head most commonly moves round its
own axis ; because the oblique direction of the neck and head
from the bone, is such, that the rotary motion of the head can
only bring the body of .the bone forwards and backwards. Nor
is the head, as in the arm, ever capable of being brought to a
straight direction with its body ; so far, however, as the head can
move within the cavity backwards and forwards, the rest of the
bone may have a partial rotation.

From the oblique position of these bones it results, that there
is a considerable distance between them above, while the knees
are almost contiguous. Sufficient space is thereby left for the
external parts of generation, for the two great outlets of urine
and faeces, and for the large thick muscles that move the thigh
inwards. At the same lime this situation of the thigh bone
renders our progression quicker, surer, straighter, and in less
room : for, had the knees been at a greater distance from each
other, we must have been obliged to describe some part of a
circle with the trunk of our body in making a long step ; and
when one leg was raised from the ground, our centre of gravity
would have been too far from the base of the other, and we
should consequently have been in danger of falling ; so that our
steps would neither have been straight nor firm, nor would it
have been possible to walk in a narrow path, had our thigh
bones been otherwise placed. In consequence, however, of the
weight of the body bearing so obliquely on the joint of the knee
by this situation of the thigh bones, weak rickety children
become knock-kneed.

The Leg

Is composed of the two bones, the TIBIA and FIBULA.
The patella being evidently appropriated to the knee-joint,
may be regarded as common both to the thigh and leg.

THE TIBIA.

205

Fig. 46,

The Tibia

Is the long thick triangular bone, situated
at the internal part of the leg, and continued
in almost a straight line from the thigh
bone. The name is derived from i'ts resem-
blance to the ancient musical instrument.

The upper end of the tibia is large, bul-
bous, and spongy. It has a horizontal sur-
face, divided into two cavities, by a rough,
irregular protuberance, which is hollow at
its most prominent part, as well as before and
behind. The anterior of the two ligaments
that compose the great crucial is inserted
into the middle cavity ; and the depression
behind receives the posterior ligament. The
two broad cavities at the sides of this pro-
tuberance are not equal ; for the internal is
oblong and deep, to receive the internal
condyle of the thigh bone ; while the exter-
nal is more superficial and round, for the
external condyle. In each of these two cavities of a recent
subject, a semilunar cartilage is placed, which is thick at its
convex edge, and becomes gradually thinner towards the con-
cave or interior edge. The thick convex edge of each cartilage
is connected to the capsular and other ligaments of the articu-
lation ; but so near to their rise from the tibia, that the cartilages
are not allowed to change their places; while their narrow ends
are fixed at the insertion of the strong cross ligament into the
tibia, and seem to have their substance united with it ; there-
fore a circular hole is left between each cartilage and the
ligament, in which the most prominent convex part of each

* The tibia and fibula of the right leg, articulated and seen from the front.
1. The shaft of the tibia. 2. The inner tuberosity. 3. The outer tnberosity.
4. The spinous process. 5. The tubercle. 6. The internal or subcutaneous
surface of the shaft. 7. The lower extremity of the tibia. 8. The internal
malleolus. 9. The shaft of the fibula. 10. Its upper extremity. 11. Its lower
extremity, the external malleolus.
18

206 TIBIA.

condyle of the thigh bone moves. The circumference of these
cavities is rough and unequal, for the firm connexion of the
ligaments of the joint. Immediately below the edge, at its
back part, two rough flattened protuberances stand out ; into
the internal, the tendon of the semimembranosus muscle is
inserted ; and a part of the cross ligament is fixed to the exter-
nal. On the outside of this last tubercle, a smooth slightly
hollowed surface is formed by the action of the popliteus
muscle.

Before the forepart of the upper end of the tibia, a large
rough protuberance rises, to which the strong tendinous liga-
ment of the patella is fixed. On the internal side of this, there
is a broad scabrous slightly hollowed surface, to which the
internal long ligament of the joint, the aponeurosis of the vastus
internus, and the tendons of the semitendinous, gracilis, and
sartorius, are fixed. Below the external edge of the upper
end of the tibia, there is a flat circular surface, covered in a
recent subject with cartilage, for the articulation of the fibula.
The body of the tibia is triangular. The anterior angle is very
sharp, and is commonly called the spine or shin. This ridge is
not straight ; but turns first inwards, then outwards, and lastly
inwards again. The plane internal side is smooth and equal,
being little subjected to the actions of muscle ; but the external
side is hollowed above by the tibialis anticus, and below by
the extensor digitorum longus and extensor pollicis longus.
The two angles behind these sides are rounded by the action
of the muscles ; the posterior side comprehended between them
is not so broad as those already mentioned, but is more oblique
and flattened by the action of the tibialis posticus and flexor
digitorum longus. A little above the middle of the bone, the
internal angle terminates, and the bone is made round by
the pressure of the musculus soleus. Near to this, the
passage of the medullary vessels is seen slanting obliquely
downwards.

The lower end of the tibia is hollowed, with a small protu-
berance in the middle. The internal side of this cavity, which
is smooth, and in a recent subject is covered with cartilage, is

FIBULA. 207

extended into a considerable process, commonly named malleolus
internus ; the point of which is divided by a notch, and from
it ligaments are sent out to the foot. The externafVide of
this end of the tibia has a rough irregular cavity formed in it,
for receiving the lower end of the fibula. The posterior side
has two lateral grooves, and a small middle protuberance. In
the internal depression, the tendons of the musculus tibialis
posticis and flexor digitorum longus are lodged ; and in the
external, the tendon of the flexor longus pollicis plays. From
the middle protuberance, ligamentous sheaths go out, for tying
down these tendons.

The Fibula

Is the small bone, placed on the outside of the leg, opposite to
the external angle of the tibia ; the shape of it is irregular.

The head of the fibula has a circular surface formed on its
inside, which, in a recent subject is covered with a cartilage ;
and it is so closely connected to the tibia by ligaments, as to
allow only a very small motion backwards and forwards. This
head is protuberant and rough on its outside, where a strong
round ligament and the musculus biceps are inserted, and,
below the back part of its internal side, a tubercle may be re-
marked, that gives rise to the strong tendinous part of the soleus
muscle.

The body of this bone is a little crooked inwards and back-
wards : which figure is owing to the actions of the muscles.
The sharpest angle of the fibula is forwards ; on each side of
which the bone is considerably, but unequally, depressed by the
bellies of the several muscles that rise from or act upon it. The
external surface of the fibula is depressed obliquely from above
downwards and backwards, by the two peronaei. Its internal
surface is unequally divided into two narrow longitudinal
planes, by an oblique ridge extended from the upper part of
the anterior angle. To this ridge the ligament stretched between
the two bones of the leg is connected. The anterior of the
two planes is very narrow above, where the extensor longus
digitorum and extensor longus pollicis arise from it : but is

208 FIBULA.

broader below, where it has the print of the peroneus tertius.
The posterior plane is broad and hollow, giving origin to the
larger share of the tibialis posticus. The internal angle of this
bone has a tendinous membrane fixed to it, from which some
fibres of the flexor digitorum longus take their rise. The
posterior surface of the fibula is the plainest and smoothest ;
but is made flat above by the splaeus, and is hollowed below by
the flexor pollicis longus. In the middle of this surface,
the canal for the medullary vessels may be seen slanting
downwards.

The lower end of the fibula is extended into a spongy oblong
head : on the inside of which is a convex, irregular, and
frequently a scabrous surface, that is received by the external
hollow of the tibia, and so firmly joined to it by a very thin
intermediate cartilage and strong ligaments, that it scarce can
move. Below this the fibula is stretched out into a smooth
coronoid process, covered with cartilage on its internal side,
and is there contiguous to the outside of the first bone of the
foot, the astragalus, to secure the articulation. This process,
named malleolus externus, being situated farther back than is
the internal malleolus, and in an oblique direction, obliges us,
naturally, to turn the forepart of the foot outwards. At
the lower internal part of this process, a spongy cavity for
mucilaginous glands may be remarked ; from its point, ligaments
are extended to the bones of the foot, viz. the astragalus, os
calcis, and os naviculare ; and from its inside, short strong ones
go out to the astragalus. On the back part of it a sinuosity is
made by the tendons of the peronei muscles. When the
ligament, extended over these tendons from the one side of the
depression to the other, is broken, stretched too much, or made
weak by the sprain, the tendons frequently start forwards to the
outside of the fibula.

The conjunction of the upper end of the fibula with the
tibia is by plain surfaces tipped with cartilage ; and at its lower
end the cartilage seems to glue the two bones together; not,
however, so firmly in young people, but that the motion at the
other end is very observable. In old subjects, the two bones

THE PATELLA OR ROTDLA. 209

of the leg are sometimes united by anchylosis at their lower
ends.

The principal use of this bone is to afford origin arvd inser-
tion to muscles ; and to give a particular direction to their
tendons. It likewise assists to make the articulation of the
foot more secure and firm, and to complete the hinge-like joint
at the ankle. The ends of the tibia and fibula being larger
than their middle, a space is here left, which is filled up with
a ligament similar to that which is extended between the
bones of the forearm ; and which is also discontinued at its
upper part, where the tibialis anticus immediately adheres to
the solaeus and tibialis posticus j but every where else k gives
origin to muscular fibres.

The Patella or Rotula

Is a small flat bone situated at the forepart of the joint of
the knee. Its shape resembles the common figure of the heart
with its point downwards. The anterior convex surface of
the rotula is pierced by a great number of holes, into which
are inserted the fibres of the strong ligament that is spread over
it. Its posterior surface is smooth, covered with a cartilage,
and divided by a middle convex ridge into two cavities, of
which the external is the largest ; and both are exactly adapted
to the pulley of the os femoris, on which they are placed in the
most ordinary unstraining postures of the legs : but, when the
leg is much bent, the patella descends far down on the condyles ;
and when the leg is fully extended, the patella rises higher in
its upper part than the pulley of the thigh bone. The plane
smooth surface is surrounded by a rough prominent edge, to
which the capsular ligament adheres. Below, the point of the
bone is scabrous, where the strong tendinous ligament from the
tubercle of the tibia is fixed. The upper horizontal part of this
bone is flattened and unequal where the tendons of the exten-
sors of the leg are inserted.

The substance of the patella is cellular, with very thin firm
external plates ; but then these cells are so small and such a
quantity of bone is employed in their formation, that scarce
18*

210 PATELLA.

any bone of its bulk is so strong. But, notwithstanding this
strength, it is sometimes broken by the violent straining effort
of the muscles.

The principal motions of the knee joint are flexion and
extension. In the former of these, the leg may be brought to
a very acute angle with the thigh, by the condyles of the thigh
bones being round, and made smooth far backwards. In
performing this, the patella is pulled down by the tibia. When
the leg is to be extended, the patella is drawn upwards, conse-
quently, the tibia forwards, by the extensor muscles; which, by
means of the protuberant joint, and of this thick bone wkh its
ligament, have the chord, with which they act, fixed to the
tibia at a considerable angle, and act, on that account, with
advantage ; but they are restrained from pulling the leg farther
than to a straight line with the thigh, by the posterior part of
the cross ligament, that the body might be supported by a firm
perpendicular column : for, at this time, the thigh and leg are
as little movable in a rotary way, or to either side, as if they
were one continued bone. But, when the joint is a little bent,
the rotula is not tightly braced, and the posterior ligament is
relaxed ; therefore, this bone may be moved a little to either
side, or with a small rotation in the superficial cavities of the
tibia ; which is done by the motion of the external cavity
backwards and forwards, the internal serving as a sort of axis.
Seeing, then, one part of the cross ligament is situated perpen-
dicularly, and the posterior part is stretched obliquely from the
internal condyle of the thigh outwards, that posterior part of the
cross ligament prevents the leg from being turned much inwards ;
but it could not hinder it from turning outwards almost round,
were not that motion confined by the lateral ligaments of this
joint, which can yield little.

This rotation of the leg outwards is of great advantage to us
in crossing our legs, and turning our feet outwards, on several
necessary occasions ; though it is necessary that this motion
should not be very large, to prevent frequent luxations here.
While all these motions are performing, the part of the tibia
that moves immediately on the condyles is that which is within

THE FOOT. TARSUS.

211

the cartilaginous rings, which, by the thickness on their out-
sides, make the cavities of the tibia more horizontal, by
raising their external side where the surface of the tibia/ slants
downwards. By these means the motions of this joint are
more equal and steady than otherwise they would have been.
The cartilages being capable of changing a little their situation,
contribute to the different motions and postures of the limb, and,
likewise, make the motions larger and quicker.

The Foot.

The foot is divided into the tarsus, metatarsus, and toes.
The sole of the foot is necessarily described as the inferior
part, and the side of the great toe as the internal.

Fig. 47,

Tarsus.

The tarsus consists of seven spongy
bones ; to wit, the astragalus, os cakis,
naviculare, cuboides, cuneiforme externum,
cuneiforme medium and cuneiforme inter-
num.

The astragalus is the uppermost of
these bones. The os calcis is below the
astragalus, and forms the heel. The os
naviculare is in the middle of the internal
sides of the tarsus. The os cuboides is the
most external of the row of four bones, at
its forepart. The os cuneiforme externum is
placed at the inside of the cuboid. The
cuneiforme medium is between the external
and internal cuneiforme bones ; and the
internal cuneiforme is at the internal side of
the foot.

The upper part of the astragalus is formed

* The dorsal surface of the left foot. i. The astragalus j its superior quadri-
lateral articular surface. 2. The anterior extremity of the astragalus, which
articulates with (4.) the scaphoid bone. 3. The os calcis. 4. The scaphoid bone.
5. The internal cuneiform bone. 6. The middle cuneiform bone. 7. The exter-
nal cuneiform bone. 8. The cuboid bone. 9. The metatarsal bones of the first
and second toes. 10. The first phalanx of the great toe. 11. The second pha-
lanx of th3 great toe. 12. The first phalanx of the second toe. 13. Its second
phalanx. 14. Its third phalanx.

212 ASTRAGALUS.

into a large smooth head, which is slightly hollowed in the
middle ; and therefore resembles a superficial pulley, by
which it is fitted to the lower end of the tibia. The internal
side of this head is flat and smooth, to play on the inter-
nal malleolus. The external side has also such a surface,
but larger, for its articulation with the external malleolus.
Round the base of this head there is a rough fossa ; and
immediately before the head, as also below its internal smooth
surface, we find a considerable rough cavity.

The lower surface of the astragalus is divided by an irregular
deep rough fossa, which, at its internal end, is narrow, but
gradually widens as it stretches obliquely outwards and
forwards. The smooth surface, covered with cartilage, behind
this fossa, is large, oblong, extended in the same oblique situa-
tion with the fossa, and concave for its conjunction with the
os calcis. The posterior edge of this cavity is formed by two
sharp-pointed rough processes, between which is a depression
made by the tendon of the flexor pollicis longus. The lower
surface before the fossa is convex, and composed of three
distinct smooth planes. The long one behind, and the exterior
or shortest, are articulated with the heel bone ; while the
internal, which is the most convex of the three, rests and moves
upon a cartilaginous ligament, that is continued from the os
calcis to the os naviculare, without which ligament the astra-
galus could not be sustained, but would be pressed out of its
place by the great weight it supports; and the other bones of
the tarsus would be separated. Nor would a bone be fit here,
because it must have been thicker than could conveniently be
allowed ; otherwise it would break, and would not prove such
an easy bending base, to lessen the shock which is given to the
body, in leaping, running, &c.

The forepart of this bone is formed into a convex oblong
smooth head, which is received by the os naviculare, and is
placed obliquely ; its longest axis inclining downwards and
inwards. Round the root of this head, especially on the upper
surface, a rough fossa may be remarked.

The astragalus is articulated above to the tibia and fibula,
which together form one cavity. In this articulation, flexion

OS CALCIS. 213

and extension are the most considerable motions ; the other
motions being restrained by the malleoli, and by the strong
ligaments which go out from the points of these processes, to
the astragalus and os calcis. When the root is bent, as it
commonly is when we stand, no lateral or rotary motion is
allowed in this joint ; for then the head of the astragalus is sunk
deep between the malleoli, and the ligaments are tense : but
when the foot is extended, the astragalus can move a little to
either side, and with a small rotation. By this contrivance, the
foot is firm, when the weight of the body is to be supported on
it ; and, when a foot is raised, we are at liberty to direct it
more exactly to the place we intend next to step upon.

The astragalus is joined below to the os calcis ; and before
to the os naviculare, in the manner to be explained when these
bones are described.

The 05 calcis is the largest bone of the seven. Behind, it is
formed into a large knob, commonly called the heel, the poste-
rior surface of which is rough below for the insertion of what
is called the tendo-achillis, and oblique above to allow the heel
to be depressed without pressing against the tendon. On the
upper surface of the os calcis, there is an irregular oblong
smooth convexity, adapted to the concavity at the back part of
the astragalus ; and beyond this a narrow fossa is seen, which
divides it from two small concave smooth surfaces, that are
joined to the forepart of the astragalus. The posterior of these
smooth surfaces, which is the largest, is the upper surface of a
process which projects inwards : and under it is a small
sinuosity for the tendon of the flexor digitorum longus.

The external side of this bone is flat, with a superficial fossa
running horizontally, in which the tendon of the musculus
peroneus longus is lodged. The internal side of the heel bone
is hollowed, for lodging the origin of the massa carnea, and for
the safe passage of tendons, nerves, and arteries. Under the
side of the internal smooth concavity, a particular groove is
made by the tendon of the flexor pollicis longus ; and from the
thin protuberance of this internal side a cartilaginous ligament
that supports the astragalus, goes out to the os naviculare ; on

214 OS NAV1CULARE.

which ligament, and on the edge of this bone to which it is
fixed, the groove is formed for the tendon of the flexor digito-
rum profundus.

The lower surface of this bone is flat at the back part, and
immediately before this plane, there are two tubercles, from
the internal of which the musculus abductor pollicis, flexor
digitorum sublimis, as also p^rt of the aponeurosis plantaris,
and of the abductor minimi digiti, have their origin ; and the
other part of the abductor minimi digiti and aponeurosis plan-
taris rises from the external. Before these protuberances, this
bone is concave, for lodging the flexor muscles; and, at its
forepart, we may observe a rough depression, from which,
and a tubercle behind it, the ligament goes out that prevents
this bone from being separated from the os cuboides.

The forepart of the os calcis is formed into an oblong pulley-
like smooth surface, which is circular at its upper external end,
but is pointed below. The smooth surface is fitted to the os
cuboides.

Though the surfaces by which the astragalus and os calcis
are articulated, seem fit enough for motion, yet the very strong
ligaments, by which these bones are connected, prevent much
motion, and give firmness to this principal part of our base,
which rests on the ground.

Os naviculare^'is somewhat oval. It is formed into an
oblong concavity behind, for receiving the anterior head of the
astragalus. The upper surface is convex. Below, the surface
is very unequal and rough ; but hollow for the safety of the
muscles. Its internal extremity is very prominent. The
abductor pollicis takes in part its origin from it, the tendon of
the tibialis posticus is inserted into it, and to it two remarkable
ligaments are fixed ; the first is the strong one, formerly men-
tioned, which supports the astragalus ; the second is stretched
from this bone obliquely across the foot, to the metatarsal bones
of the middle toe, and of the toe next to the little one. On the
outside of the os naviculare there is a semicircular smooth
surface, where it is joined to the os cuboides. The forepart of
this bone is covered with cartilage, and divided into three
smooth planes, fitted to the three ossa cuneiformia.

i& ivyti ^j LO^>

OS CUBOIDES. OS CUNEIFORMS EXTERNUM. 215

•

The os naviculare and astragalus are joined as a ball and
socket ; and the naviculare moves in several directions in turn-
ing the toes inwards, or in raising or depressing either ^ide of
the foot, though the motions are greatly restrained by the liga-
ments which connect this to the other bones of the tarsus.

Os Cuboides is an irregular cube. Behind, it is formed into
an oblong unequal cavity, adapted to the forepart of the os
calcis. On its internal side, there is a small semicircular smooth
cavity, to join the os naviculare. Immediately before which,
an oblong smooth plane is made by the os cuneiforme exter-
num ; below this the bone is hollow and rough. On the internal
side of the lower surface, a round protuberance and fossa are
found, where the musculus abductor pollicis has its origin. On
the external side of this surface, there is a broad ridge running
forwards and inwards, covered with cartilage ; immediately
before which a smooth fossa may be observed, in which the
tendon of the peroneus primus runs obliquely across the foot.
Before, the surface of the os cuboides is flat, smooth, and
slightly divided into two planes, for sustaining the os metatarsi
of the little toe, and of the toe next to it.

The form of the back part of the os cuboides, and the liga-
ments connecting the joint with the os calcis, both concur in
allowing little motion in this part.

Os cuneiforme externum is shaped like a wedge, being
broad and flat above, with long sides running obliquely down-
wards, and terminating in an edge. The upper surface of this
bone is an oblong square. The one behind is nearly a triangle,
but not complete at the inferior angle, and is joined to the os
naviculare. The external side is an oblong square divided as
it were by a diagonal ; the upper half of it is smooth, for its
conjunction with the os cuboides : the other is a scabrous hol-
low, with a small smooth impression made by the os metatarsi
of the toe next to the little one. The internal side of this bone
is flattened before by the metatarsal bone of the toe next to the
great one, and the back part is also flat and smooth where the os
cuneiforme medium is contiguous to it. The forepart of this bone
is triangular, for sustaining the os metatarsi of the middle toe.

216 OS CUNEIFORMS.

Os cuneiforme, or minimum, is still more exactly the shape
of a wedge than the former. Its upper part is square ; its in-
ternal side has a flat smooth surface for its connexion with the
adjoining bone; the external side is smooth and a little hol-
lowed, where it is contiguous to the last described bone. Be-
hind, this bone is triangular, where it is articulated with the os
naviculare ; and it is also triangular at its forepart, where it is
contiguous to the os metatarsi of the toe next to the great one.

The broad thick part of the os cuneiforme maximum, or in-
ternum, is placed below, and the small thinner edge is above.
The surface of the os cuneiforme behind, where it is joined to
the os naviculare, is hollow, smooth, and of a circular figure
below, but pointed above. The external side consists of two
smooth and flat surfaces. With the posterior, that runs ob-
liquely forwards and outwards, the os cuneiforme minimum is
joined ; and with the anterior, whose direction is longitudinal,
the os metatarsi of the toe next to the great one is connected.
The forepart of this bone is flat and smooth, for sustaining the
os metatarsi of the great toe. The internal side is scabrous,
with two remarkable tubercles below, from which the muscu-
lus abductor pollicis rises, and the tibialis anticus is inserted
into its upper part.

The three cuneiforme bones are all so secured by ligaments,
that very little motion is allowed in any of them.

These seven bones of the tarsus, when joined, are convex
above, and leave a concavity below, for lodging safely the
several muscles, tendons, vessels, and nerves, that lie in the
sole of the foot. In the recent subject, their upper and lower
surfaces are covered with strong ligaments, which adhere firmly
to* them ; and all the bones are so tightly connected by these
and the other ligaments, which are fixed to the rough ridges
and fossae, that notwithstanding the many surfaces covered
with cartilage, some of which are of the form of the very
movable articulations, no more motion is here allowed, than
is necessary to prevent too great a shock of the fabric of the
body in walking, leaping, &c., by falling on too solid a base.
If the tarsus was one continued bone, it would likewise be

METATARSUS.

217

much more liable to be broken, a-nd the foot could not accom-
modate itself to the surfaces we tread on by becoming more
or less hollow, or by raising or depressing either of its sid^s.

Metatarsus.

The Metatarsus is composed of five bones, which agree, in
their general characters, with the metacarpal bones ; but may
be distinguished from them by the following marks : 1. They
are longer, thicker, and stronger. 2. Their anterior round ends
are not so broad, and are less in proportion to their basis.

3. Their bodies are sharper above and flatter on their sides,
with their inferior ridge inclined more to the outside. 4. The
tubercles at the lower part of the round head are larger.

Fig. 48.* The first or internal metatarsal bone is

easily distinguished from the rest by its
thickness. The one next to it is the
longest, and with its sharp edge almost
perpendicular. The others are shorter
and more oblique, as their situation is
more external. Which general remarks,
with the description now to be given of
each, may teach us to distinguish them
from each other.

Os metatarsi potticis is by far the.
thickest and strongest, as having much
the greatest weight to sustain. Its base
is oblong, irregularly concave, and of a
semilunar figure, to be adapted to the os
cuneiforme maximum. • The inferior edge
of this base is a little prominent and rough,

* The sole of the left foot. 1. The inner tuberosity of the os calcis. 2. The
outer tuberosity. 3. The groove for the tendon of the flexor longus digitorum.

4. The rounded head of the astragalus. 5. The scaphoid bone. 6. Its tuberosity.
7. The internal cuneiform bone ; its broad extremity. 8. The middle cuneiform
bone. 9. The external cuneiform bone. 10, 11. The cuboid bone. 11. Refers
to the groove for the tendon of the peroneus longus. 12, 12. The metatarsal
bones. 13, 13. The first phalanges. 14, 14. The second phalanges of the four
lesser toes. 15, 15. The third, or uugual phalanges of the four lesser toes. 16»
The last phalanx of the great toe.

19

218 METATARSUS.

where the tendon of the peroneus primus muscle is inserted.
On its outside, an oblique circular depression is made by the
second metatarsal bone. Its round head has generally on its
forepart a middle ridge, and two oblong cavities, for the ossa
sesamoidea ; and, on the external side, a depression is made by
the following bone.

Os metatarsi of the second tof is the longest of the five, with
a triangular base supported by the os cuneiforme medium, and
the external side produced into a process ; the end of which is
an oblique smooth plane, joined to the os cuneiforme externum.
Near the internal edge of the base, this bone has two small
depressions, made by the os cuneiforme maximum, between
which is a rough cavity. Farther forwards we may observe
a smooth protuberance, which is joined to a foregoing bone.
On the outside of the base are two oblong smooth surfaces for
its articulation with the following bone ; the superior smooth
surface being extended longitudinally, and the inferior perpendic-
ularly, between which there is a rough fossa.

Os metatarsi of the middle toe is the second in length. Its
base, supported by the os cuneiforme externum, is triangular,
but slanting outwards, where it ends in a sharp-pointed little
process, and the angle below it is not completed.

The internal side of this base is best adapted to the preceding
bone ; and the external side has also two smooth surfaces
covered with cartilage, but of a different figure ; for the upper
one is concave, and being round behind, turns smaller as it
advances forwards; and the lower surface is a little smooth,
convex, and very near the edge of the base.

Os metatarsi of the fourth toe is nearly as long as the former,
with a triangular slanting base joined to the os cuboides, and
made round at its external angle ; having one hollow smooth
surface on the outside, where it is pressed upon by the following
bone ; and two on the internal side, corresponding to the former
bone, behind which is a long narrow surface impressed by the os
cuneiforme externum.

Os metatarsi of the little toe is the shortest, situated with
its two flat sides above and below, and with the ridges laterally

STRUCTURE OF THE FOOT. 219

The base of it, part of which rests on the os cuboides, is very
large, tuberous, and produced into a long-pointed process
externally, where part of the abductor minimi digiti infixed;
and into its upper part the peroneus secundus is inserted. Its
inside has a flat conoidal surface, where it is contiguous to the
preceding bone.

When we stand, the fore ends of these metatarsal bones,
and the os calcis, are our only supporters, and, therefore, it is
necessary that they should be strong, and should have a confined
motion.

The Toes.

The bones of the toes are nearly similar to those of the
thumb and fingers ; particularly the two of the great toe,
which are precisely formed as the two last of the thumb ; but
their position, as respects the other toes, is not oblique ; and
they are proportionally much stronger, because they are sub-
jected to a greater force ; for they sustain the impulse by which
our bodies are pushed forwards by the foot behind at every
step we make, and on them principally the weight of the body
is supported, when we are raised on our tip-toes.

The three bones in each of the other four toes, compared
with those of the fingers, differ from them in these particulars.
They are less, and smaller in proportion to their lengths. Their
basis are much larger than their anterior ends. The first pha-
lanx is proportionally much longer than the bones of the second
and third, which are very short.

The toe next to the great one has the largest bones in all
dimensions, and the bones of the other toes diminish according
to the order of their position ; those of the exterior being least.

The General Structure of the Foot.

The foot may be considered as an arch, of which the back
part of the heel, and the anterior extremities of the metatarsal
bones and the toes, are the abutments. The heel, or posterior
abutment is not so broad as the anterior, and is placed on the
outside and not in the middle of the extremity of the arch. The

220 STRUCTURE OF THE FOOT.

process on the inside of the os calcis, which supports the
astragalus, increases the breadth of the arch ; and the os
naviculare completes it. The arch, thus constructed, does not
appear very firm, and this apparent want of strength seems
increased by the position of the anterior portion of the astra-
galus, a part of which is between the os calcis and os naviculare,
and not supported by either. These bones, however, are
firmly connected by ligaments, and one which passes from the
os calcis to the os naviculare, under the forepart of the astra-
galus, gives effectual support to that bone.

The outside of the foot, formed by the os calcis, os cuboides,
and the lesser metatarsal bone, does not partake much of the
nature of an arch ; for it is almost flat. As the internal side
forms a considerable arch, the foot is to be considered as
possessing a double convexity, viz. transversely, as well as
longitudinally. 2f

The great toe, from its internal situation, is the principal
anterior abutment of the arch on the internal side of the foot ;
hence its great importance.

The astragalus, which is the basis of the tibia, and of course
pressed by half of the weight of the body when we stand,
appears to be in a situation which is very oblique, and imper-
fectly supported ; and accordingly it has been completely
forced from its position, by accidents in which the leg has
been twisted or turned inward, and the foot prevented from
turning with it. It is probable that this misfortune would
often take place if the fibula did not previously yield, as in
some of the cases of fracture of that bone near the external
ankle.

One great object of this peculiar structure is, that the foot
may yield in cases of violent and sudden pressure, as when we
jump or fall upon the feet. The safety of the foot, and the
facility of its ordinary movement, are not the only objects of
its peculiar structure, but concussion of the whole body, and
particularly of the brain, is thereby avoided to a certain de-
gree.

^his may be inferred from the fact that many persons suffer
* \=^ C-' / 2fc+* **

/, &r«

SESAMOID BONES. EXTREMITIES OF THE FffiTUS. 221

violent concussions, in consequence of falling upon other parts
of the body, who are free from these effects when they fall
upon the feet.

The Sesamoid Bones

Are seldom larger than half a pea. They are most commonly
found at the second joint of the thumb, and of the great toe ;
and are placed in pairs, especially at the great toe, between the
tendons of the flexor muscles and the bones.* In these situa-
tions they are convex externally, and on their internal surfaces
they are concave and covered with cartilage.

They are also sometimes found between the heads of the
gastrocnemius muscle and the condyles of the os femoris.

In the joints of the thumb and toe they appear to be very
analogous to the patella.

— Besides the four pair of sesamoid bones above described as
belonging to the skeleton, viz. two upon the metacarpo-pha-
langeal articulation of each thumb, and two upon the corres-
ponding joint of each great toe, there is often found in addition,
one upon the metacarpo-phalangeal joint of the little finger,
and upon the corresponding joint in the foot. There is one
also often met with in the tendon of the peroneus longus muscle,
where it glides through the groove in the cuboid bone. Some-
times they are found in the tendons that wind round the inner
and outer malleolus and in the psoas and iliacus where they
glide over the body of the os pubis. —

The Extremities of the Foetus.

In the upper extremity the clavicle is almost perfect at birth ;
but the acromion and coronoid processes of the scapula, as well
as the head, are in a cartilaginous state.

Both ends of the os humeri are cartilaginous. They after-
wards ossify in the form of epiphyses, and are united to the
body of the bone.

The two bones of the forearm are in the same situation.

* They are properly speaking developed in the tendons of these muscles, like
the patella in the tendon of the extensor muscles of the thigh. The patella
itself may be considered a specimen of a sesamoid, considering its mode of
development. — p.

19*

222 EXTREMITIES OF THE FffiTUS.

There are no bones of the carpus ; but in their situation is an
equal number of cartilages, which resemble them exactly.
These cartilages are separated from each other, by synovia
membranes, as the bones afterwards are. Each of them
ossifies from a single point, except the unciforme.

The metacarpal bones, and the first bone of the thumb
have cartilages at each extremity, which afterwards become
epiphysis.

The bones of the phalanges are likewise cartilaginous at each
extremity. The extremities next to the hand are epiphyses ;
but it is probable that the other extremities ossify gradually
from their centres.*

In the lower extremity, the head and neck, and two tro-
chanters of the os femoris are cartilaginous and form three
epiphyses.

The other end of this bone is also cartilaginous, and consti-
tutes but one epiphysis, notwithstanding its size ; the ossification
commencing in the centre.

At birth, the body of the os femoris is less curved than it
becomes afterwards ; and the angle formed by the neck of the
bone is less obtuse than in the adult.

The patella is entirely cartilaginous at birth.

The two extremities of the tibia and fibula are also cartilag-
inous, and become epiphyses.

The astragalus and os calcis are somewhat ossified within,
and have a large portion of cartilage exteriorly.

In place of the other bones of the tarsus there are cartilages
of their precise shape, which are as distinct from each other as
the future bones are.

The state of the metatarsal bones, and the phalanges of the
toes, resembles that of the bones of the hand.f

* See Nesbit's Osteology, page 126.

f Volehn Koyter, a disciple of Fallopius, has given to the profession one of
the best accounts of Osteogeny, according to Lassus. — H.

PART II.

SYNDESMOLOGY.

CHAPTER III.

GENERAL ANATOMY OF THE LIGAMENTOUS, FIBROUS, OR
DESMOID TISSUE.

Of the ligaments aud membranes which connect the different parts of the body
to each other— Of the articular cartilage— Fibro-cartilages— Synovial cap-
sules, and particular articulations.

THE tendons and the strong membranes connected with them
called aponeuroses, the fascia which bind down some of the
muscles and afford an origin to many of their fibres, and the
membranes which confine the tendons, appear to be composed
of the same substance.

— Notwithstanding some slight shades of difference which
exist in the physical and chemical composition of these different
parts, they are all now included with the periosteum, perichon-
drium, dura mater, sclerotic coat of the eye, &c., under the
general head of ligamentous, fibrous, or desmoid tissue.*
This tissue is sometimes called, from the whiteness of its
appearance, the albugineous tissue. It is spread very gene-
rally throughout the body, and is found wherever extraordinary
strength and resistance is required, without elasticity or muscu-
lar contraction. It has been called ligamentous or desmoid,
from its fastening together the bones and cartilages, as in the
ligaments proper, and from binding down the muscles so as to
preserve the symmetry of the limbs, in the form of fascia and

* The term ligament is frequently, though not with exact propriety applied to
the duplicatures of serous membranes, which are attached to and assist in sup-
porting different viscera, as the liver, bladder, uterus, &c., since these do not
belong to the fibrous or desmoid tissue. — p.

2'24 FIBROUS TISSUE.

aponeurosis, and from fastening the tendons in their grooves
in the form of their theca's or sheaths. The term fibrous was
applied to it by Bichat, (though its elements are dissimilar to
muscular fibre,) in consequence of its performing the office of
bands or chords, and being composed essentially of firm in-
elastic threads, or albuminous fibres. These fibres crossing
each other in various directions and woven densely together,
with some intervening cellular tissue, form the aponeuroses,
fascia?, sheaths, articular capsules, periosteum, dura mater,
and tunica albuginea ; arranged longitudinally, they form the
tendons of the muscles and the straight ligaments of the joints.
The tendons, by a little dissection, may be spread out into a
membrane, and in some parts of the body we see them naturally
unfolding themselves to form an aponeurosis.
— Between all these different parts there is more or less con-
nexion. The tendons are inserted upon the bones only through
the intermedium of the periosteum, by which the bones are
covered. The aponeuroses are connected with the periosteum
by the fasciae which they send down between the muscles.
The ligaments and periosteum are directly continuous, and
the dura mater, as it sends out processes around the nerves,
becomes continuous with the periosteum that lines the foramina
of the bones, through which the nerves pass. Bichat, con-
sidered the periosteum the source and centre of this system ;
Bonn, of Amsterdam, as well as Clarus, believed the aponeu-
roses investing the limbs to be the centre ; — an opinion more
venerable than either of these, that of the Arabian anatomists,
fixed it in the dura mater. But, in truth there is no proper
centre. In many parts, there is a fibrous tissue isolated from
the rest, as the investing coat of the spleen and kidneys, and
the fibrous portion of the pericardium.

— The fibrous tissue in all parts of the body is continuous, at
its surfaces and margins, with the common cellular tissue, and
in many parts we find it, especially in the aponeuroses and
fasciae, degenerating insensibly into it. There appears in fact
to be a close relationship between these two tissues ; in its
development in the foetus, it first appears as a soft, flexible,

FIBROUS TISSUE. 225

i

extensible, homogeneous tissue, resembling much the cellular,
and presents no appearance of fibres, till near the period of
birth. As life advances it becomes more hard, soliti*^ and
yellow, and in extreme old age presents much rigidity, and is
occasionally even converted into bone. When macerated in
water, or imbued with fluids, as in scrofulous inflammation of
the joints, it presents a pulpy, spongy appearance, in the cells
of which the fluid is contained. If the maceration is carried
only to a limited extent, the fibres will separate into filaments,
as delicate as those of the silk worm ; but by prolonged mace-
ration these filaments themselves disappear in the cellular
mass. Mascagni, believed these fibres were lymphatics en-
closed in a vascular web. Beclard, that they were nothing but
condensed cellular tissue. Isenflam, that it was cellular tissue,
with the walls imbued and the cells filled with gluten and
albumen, and more or less in the advance of life with earthy
matter; an opinion which seems to accord with the different
phases which the tissue presents. Chaussier and Bichat, con-
sidered the fibre as primitive and peculiar, and that maceration
only brought into view the cellular tissue which connected the
fibres together.

— However this may be, and it is a question not yet decided,
in the form in which it presents itself to study, it differs in
many respects from cellular tissue. It is not elastic or yielding
to the application of sudden force as the latter ; the fibres will
break or tear up at their bony attachment, but cannot be
stretched or strained in the proper sense of the word. But
when the force is gradually applied, as by the accumulation of
a fluid in a joint, they yield to receive it, by a sort of interstitial
expansion or growth, and retract in the same gradual manner,
when the distending power is removed. Fibrous tissue contains
but little adipose matter, and is affected only to a slight extent
in anasarca.

— The labors of the microscopists have recently confirmed the
opinion of Chaussier and Bichat.

— They have shown fibrous tissue to consist of fine transparent
undulating cylindrical filaments, about i^00 part of an inch in

226 FIBROUS TISSUE.

diameter. They are generally collected in minute fasciculi,
from 5^00 to T0^g and these again into larger fasciculi ^ to ^ of
an inch wide, the filaments of which are held together, by a firm
structureless amorphous substance, which has received the name
of cytoblastema. Under the microscope, the elementary struct-
ure of the cellular, fibrous and fibro-cellular tissues, appear to be
the same. Their anatomical ^differences depending on the mode
in which their elementary fibres are put together. In fibrous
tissue the undulating primitive filaments are arranged side by side
into fasciculi, which differ from those of cellular tissue in being
much larger, more dense and more opaque and in being straight
instead of flexuous. Their whiteness and strength, depend
upon the compact parallel disposition of the compound fila-
ments ; and their slight amount of elasticity is owing to the
absence* of sinuosity in the arrangement of the compound
fasciculi. According to the manner in which these fasciculi or
fibres are arranged and combined, we have either the mem-
branous or fascicular form of fibrous tissue as has been above
explained. Cellular membrane in a more or less condensed
state, is found in general intermixed to a greater or less extent,
with the fibrous fasciculi.

The Ligaments of the Joints,

— Are all divided into the capsular or bag-like, and into funicu-
lar, or cords.

— The capsular, or fibrous bags, of greater or less thickness,
open at both ends, into which the heads of the bones forming
the respective joints are thrust, and round the necks of which
it is closely inserted, where they are continuous with the peri-
osteum of the bones. In very many of the joints the capsules
are imperfect in some part of their periphery, and in others
are represented only by a few scattered fibres. The hip and
shoulder joint furnish the best specimen of a perfect capsule.
— The funicular ligaments are cords, flat, round, or oval,
intended to give a side support to the joints, and constitute
the lateral ligaments. These are placed, some within, some-

FIBROUS TISSUE. 227

without, and some in the very thickness of the capsular liga-
ment.—

They consist of fibres which are flexible but extrefnely
strong, and in general have but little elasticity ; their surfaces
are smooth and polished ; their color is whitish and silver-
like.

The vessels which enter into their composition do not com-
monly carry red blood ; and although it seems certain that
they must have nerves, many very expert anatomists have declar-
ed that no nerves could be traced into them.
— A branch of the fourth cranial nerve, has however been
found distributed in the dura mater. Blood vessels abound in
the periosteum, but they merely divide in that membrane, so
as to enter the bone at a great number of points, as has been
before observed. —

In a healthy state, they are entirely void of sensibility, and ^
can be cut and punctured, or corroded with caustic appli-
cations, without pain. When inflamed they are extremely
painful.

The ligaments which connect the different bones to each
other, have a very strong resemblance to these tendinous parts,
not only in their structure but in their qualities also. Many of
them appear rather more firm in their texture and more vascular.
Their vessels are also larger: their color sometimes inclines to a
dull white, and when examined chemically, they appear to
differ, in some respects, from tendons. t

They agree, however, with the tendinous parts as to their
insensibility in a sound state, and the extreme pain which occurs
when they are inflamed. No nerves have been traced into their
structure.

Notwithstanding the ordinary insensibility of these parts, it
was asserted by M. Bichat that several animals who seem to
suffer no pain from cutting, puncturing, or corroding the liga- \
ments of their joints, appeared to be in great agony when
these parts were violently stretched or twisted ; and he de-
clared this to be the case when all the nerves which passed
over the ligaments, and could have been affected by the

228 FIBROUS TISSUE.

process, were cut away. He explained by this the pain which
sometimes occurs instantaneously in sprains, in the reduction of
luxations, and in other analogous processes.

The ultimate structure of these parts is, perhaps, not perfectly
understood.

An anatomist of the highest authority, Haller, appears to
have considered them as fqrmed of membrane, while a late
writer, who has paid great attention to the subject, and is also
of high authority, M. Bichat, has satisfied himself that their
structure is essentially fibrous.

If a tendon, or portion of tendinous membrane, be spread
out, or forcibly extended, in a direction which is transverse
with respect to its fibres, it will seem to be converted into a
fine membrane, and the fibres will disappear to the naked eye.
The same circumstances will occur when a ligament is treated
in a similar way ; but much more force is required.

Thus constructed, these parts are perfectly passive portions of
the animal fabric, and have no more power of motion than the
bones with which many of them are connected.

But notwithstanding their ordinary insensibility, they often
induce a general violent affection of the system when they are
diseased. A high degree of fever, as well as severe pain,
attends their acute inflammations ; and hectical symptoms, in
their greatest extent, are often induced by their suppurations.

There is another circumstance in their history which is very
difficult to reconcile with their ordinary insensibility. They are
the most common seats of gouty painful affections.

In these cases, pain does not seem to be the simple effect of
inflammation : it often occurs as the first symptom of the dis-
ease ; it frequently exists with great violence for a short time and
goes off without inflammation, and it is frequently vicarious with
affections of the most sensible and irritable parts, -v

Parts of a tendinous and ligamentous structure do not appear
retentive of life, but lose their animation very readily, in conse-
quence of the inflammation and other circumstances which attend
wounds.

When thus deprived of life, they retain their usual appear-
- %#^,

^^ v", ***•? *) ts*J**r»jL.&£^ ft>Cs&^

+-*£<, ~^f'

\. sfi&^-^tf — jffif^

' •&* "*^&j £fT jtffa, ev^^V

YELLOW ELASTIC LIGAMENTOUS TISSUE.

229

ance and their texture a long time. The dead parts separate
from the living in large portions, in a way which has a con-
siderable analogy with the exfoliation of bones.

The tendons and their expansions, and the various fasciae,
have the same chemical composition. If boiled a long time,
they dissolve completely, and form the substance called by
chemists gelatine, or pure glue.

The ligaments differ from them in some respects. When
boiled they yield a portion of gelatine, and do not dissolve
entirely ; but are said to retain their form and even their
strength, after a very long boiling. The composition of the
part so insoluble in water, has not yet been ascertained.

Of the Yellow Elastic Ligamentous Tissue.

Fig. 49.* — This is a modification of

the common ligamentous tis-
sue,*which though not usual-
ly treated apart, differs from
it in many essential particu-
lars. It contains, according
to the younger Girard, some
fibrine in its composition ; it
is eminently elastic, and is
placed to give resistance and
support to parts, where in
other animals, we meet with
muscular fibres, for which it is in some sort a substitute. In some
situations it is of a deep yellow color, and rarely presents the
silvery aspect of the common tissue. It forms the middle coat
of the arteries, the ligaments between the bridges of the verte-
brae, the ligamentum nucha3 in quadrupeds with heavy pen-
dant heads, the elastic involucrum oj the corpus cavernosum
and spongiosum penis in the male, of the clitoris in the female,

* Reticulate elastic tissue from the ligamentum nuchae of the horse magnified
to 200 diameters (from Gerber). a. Loosened elastic tissue with the meshes
opened, b. Elastic tissue in its natural condition, the meshes close j the fibres
being disposed in lines and layers, parallel to one another.
20

230

FIBRO-LIGAMENTOUS TISSUE.

/ and the elastic covering of the spleen ; it is found in the rami-
fications of the bronchia, in various parts of the eye ball, and in
the ligaments of the larynx and os hyoides including the vocal
chords ; we might also add, the elastic membrane of the nose
and ear, which are more allied to it, than to cartilage, though
they are called membraniform cartilage. This yellow elastic
tissue, (tissue jaune) unlike otfcer ligamentous tissue, yields no
gelatine on boiling. It resists decomposition for a very long
time, either by maceration, putrefaction, or digestion ; it becomes
brown and transparent on drying, but not brittle like cartilage.
Fig. 50.* When examined with the mi-

croscope, it is found to bear in
the arrangement of its fibres
a strong resemblance to a
net work of capillary vessels.
Its fibres are rigid, prismatic
in form and about the ^g
part of a line in diameter,
highly elastic and interlaced
with each other at all angles ;
its embryonic cells are elon-
gated and mixed with the
fibres. If injured it is very
imperfectly reproduced ; a dense fibrous tissue being substi-
tuted in its place. It is very sparingly supplied with blood-
vessels.

Of the Fibro-cartilaginous or Ligamento-cartilaginous Tissue.

— There is another variety of the desmoid tissue, which holds
a middle station between ligament and cartilage, partakes
partly of the nature of both, and has been treated of by Bichat
as a distinct tissue under this compound name. Vesalius and

* Elastic tissue from the middle fibrous coat of the aorta of the ox magnified
300 diameters. The intertangled fibres, and elongated cells are well shown
(from Gerber). These fibres, according to Henle, are contractile, and resemble
.somewhat the muscular fibres of the stomach.

FIBRO-LIGAMENTOUS TISSUE. . 231

Morgagni, called them cartilaginous ligaments ; Haase, mixed
ligaments. Like ligaments, they present a well marked fibrous
appearance, and are strong and resisting. Like cartilages,
they are white, very dense and elastic. Beclard divides them
into the temporary and permanent.*

— The temporary, are those which pass regularly and at
determined periods to the state of ossification, and are developed
in the midst of the ligaments and tendons, as the patella and
sesamoid bones.

— The permanent are of several kinds. 1. Those which are
free at both these surfaces, and are lined by the synovial mem-
brane. These constitute the interarticular or meniscous carti-
lages, (menisci,) and are attached at their outer surface to the
inner face of the capsular ligament. They are found in the
knee, maxillary, clavicular, and lower ulnar articulations.
2. Those which are adherent by one of their surfaces ; these
are found whenever the fibrous tissue is subjected to habitual
friction by the tendons, as in the different grooves, through
which they play, or upon the sides of the ligaments or carti-
lages, against which they rub ; the periosteum, or whatever
fibrous membrane it may be, first becomes thickened and then
converted into a semicartilage. It also exists in the fibrous
rings, placed at the margin of the glenoid and cotyloid cavities
for the purpose of deepening their sockets. 3. Those adherent
by both surfaces. These are found between the bodies of the
vertebrae and the pubic bones.

— The accidental production of this tissue is by no means
uncommon ; it is found occasionally in the cavities of fractures
forming false joints, in the tubercular cavities of the lungs, in
the uterus, ovaries, etc.

* Bichat considered the elastic cartilaginous membranes of the nose, ear, and
trachea, as belonging to this division of the tissues, but they certainly have a
closer affinity to the yellow elastic fibrous tissue. — p.

232 OF ARTICULATIONS.

CHAPTER IV.

A GENERAL ACCOUNT OF ARTICULATIONS, AND OF

Of Articulations.

THOSE surfaces of bones which form the movable articula-
tions are covered with cartilaginous matter which has been
already described.*

— In many of the immovable articulations, as the sacro-iliac
symphysis for instance, a thin lamen of cartilaginous matter,
with all the other appurtenances of joints, are likewise met
with. The connexion between the articular cartilage and the
bones is strong, but its nature is not well known. None of
the vessels of the bone pass into the cartilage, but terminate in
its immediate neighborhood. Gerdy, (page 29) considers it
a secretion from these vessels, and that its formation is like
that of the cuticle, from the vessels of the skin. This, however,
is but a mere opinion, unsustained by proof. It presents the
appearance of a couch of white wax spread over the end of
the bones, though it is composed of vertical fibres like the frill
of velvet, so crowded together as to leave no sensible interval
between them, and presenting a free extremity to the cavity of
the joint. The cartilages terminate insensibly at their circum-
ference on the surface of the bone. On the heads of the bones
they are thicker at the central part, than at their circumference ;
in the corresponding socket, the cartilaginous coating is thickest
at the margin, and sometimes spreads out into a sort of carti-
laginous rim. —

— On the formation of the epiphysis of the long bones, and its
covering cartilage. — In the foetus and young subject, there is
no distinction between the cartilage that is to become the bone
of the epiphysis and that which is to remain as articular carti-

* See page 36.

FORMATION OF THE EPIPHYSIS OF LONG BONE. 233

•

lage. In my preparations alluded to, page 236, a careful dis-
section shows branches running from the zone of vessels across
the head of the bone isolating the articular cartilage froni the
epiphysal. These branches have beds of bone formed round
them, communicate freely with the vessels of the epiphysis,
but appear to send no branches towards the free surface of the
articular cartilage. The portion of the articular cartilage
immediately overlaying them, is , however , more tough and
periosteal in its character, than that on the free surface of the
cartilage, and has been, though not with exact propriety,
described by Mr. Listen, as cellular tissue connecting the carti-
lage and epiphysis. It is well known that in young subjects, the
articular cartilage is thick, and fhe compact layer of the epi-
physis below it thin and fragile ; while in old persons the com-
pact layer of the epiphysis is thick and strong, and the cartilage
covering is thin, rigid, and so firmly united to the bone below,
as to be with difficulty removed from it by the ordinary process
of cleaning. It would seem from this, that .while the cartilage
gets its nutritive fluids by imbibition from the epiphysal vessels
and the marginal zone, some change is effected by their passage
into its structure during the progress of life, by which the inner
portions of the articular cartilage is converted into bone.
Though in the healthy state no vessels can be injected in carti-
lage, in some diseases of the joints blood-vessels and granula-
tions may shoot up from the bone below into the place of the
cartilage. — It has been most probably in cases of this de-
scription, that the appearance of vascularity in the cartilages
has been observed; that of Mr. Liston, detailed in a late num-
ber of the medico-chirurgical transactions was from a diseased

The bones are retained in their relative situations by liga-
ments, such as have been lately mentioned, which are exterior
to the cavities of the articulations, and placed in such situa-
tions that they permit the motions the joints are calculated
to perform, while they keep the respective bones in their
proper places.

20*

234 SYNOVFAL CAPSULES.

Of the Synovial Capsules.

•< — The synovial capsules are formed of an extremely thin
transparent, double reflected tissue, the vessels of which circu-
late in the healthy state only the serous portions of the blood,
and which, though erected into a distinct tissue or system by
Bichat, under the name of synovial, is now generally considered
as forming only a part of th£ general serous tissue, which it
closely resembles in structure, and with which it intimately
sympathizes in disease. They are of three kinds : 1st. Those
which line the inner surface of the ligaments of the joints, and
are reflected over the surfaces of the articular cartilages. These
are called the articular synovial cartilages. 2d. Those which
are placed between the tendons of the muscles, and the bones
and cartilages against which the tendons rub. These are called
burscE mucoscs. 3d. Those which are placed between the* skin
and the bones, tendons, or other hard parts, over which it per-
forms frequent and extensive movements. These are called the
subcutaneous synovial capsules. —

Of the Articular Synovial Capsules.

They are invested in a particular manner by a thin delicate
membrane, which in some joints, as those of the hip and
shoulder, seems to be the internal lamina of a stronger liga-
ment called the capsular ; and, in other joints, the knee, for
example, appears to be independent of any other structure.
In each case, this synovial membrane, as it has lately been
called, forms a complete sac or bag which covers the articular
surface of one bone, and is reflected from it to the correspond-
ing surface of the other ; adhering firmly to each of the
articulating surfaces, and extending loosely from the margin of
one surface to that of the other.

In the distribution it supplies the place of perichondrium to
the cartilages, and of periosteum to those surfaces of bone with
which it is connected.

It seems greatly to resemble the membranes which line the

- ' ;4&**v.

-U^2 <V"~- -/

SYNOVIAL CAPSULES. 235

abdomen and thorax, and invests the parts contained in these
cavities ; and like them it may be termed a reflected membrane.

It is thin and very flexible, but dense and strong. ;

It secretes, or effuses from its surface, a liquor, called synovia ;
which is particularly calculated to lubricate parts that move
upon each other, x*

The fluid is nearly transparent : it' has the consistence of a
thin^yjuj^and is very tenacious or ropy. It mixes with cold
water, and, when heated, becomes milky, and deposits some
pellicles without losing its viscidity. It appears to be composed
of eighty parts in one hundred of water ; above eleven parts of
fibrous matter; and between four and five parts of albumen.
It also contains a small portion of soda, of muriate of soda, and
of phosphate of lime. t

There are in many of the joints masses of fat which appear
to project into the cavity, but are exterior to the synovial
membrane, and covered by it ; as the viscera in the abdomen
are covered by the peritoneum.

They are generally situated so as to be pressed gently, but
not bruised, by the motions of the bones.

In some joints, they appear like portions of the common
adipose membrane ; in others, they appear more vascular, and
have a number of blood-vessels spread upon them. Small
processes often project from their side like fringe.

These masses have been considered as synovial glands ; but
they do not appear like glands ; and it is probable that the
synovia is secreted by the whole internal surface of the mem-
brane.*

, The synovial membrane, like the other parts of joints, is
' insensible in a sound state, but extremely painful when inflamed.
The synovia, which is secreted, during the inflammation of this
membrane, has a purulent appearance.

— For the sake of facility in description it is common among
anatomists, without admitting or denying the fact, to consider

* Clopton Havers, ignorant that the synovia was derived by a sort of perspira-
. lion from the inner surface of this membrane, supposed it to be secreted by these
masses of adipose matter, which are still known, in perpetuation of his mistake,
as Havers' glands.— T.

- f^ JL&.

'tl^C** -

\

236 SYNOVIAL CAPSULES.

the synovial membrane as passing over the face of the articular
cartilages ; it has however long been a question among anato-
mists and surgeons, whether such be really the case. It can
only be traced by the knife as far as the circumference of the
cartilages, nor can vessels by any means in the healthy state
be injected in it beyond this point. If it exist upon the carti-
lages, it is certainly so modifieq^ as not to be recognizable. It is
asserted by Mr. Toynbee* that it covers the cartilage as a
vascular membrane only in the early periods of foetal life — and
that towards the period of birth the sub-synovial vessels, gradu-
ally recede from the surface of the articular cartilage and form
a zone around its margin ; a change somewhat like that which
takes place in the membrana pupillaris. I have several
minutely injected preparations of the joints taken from young
subjects, which show this zone of vessels, arranged in loops
somewhat like the mesenteric arches, around the beveled cir-
cumference of the cartilage, which are strongly confirmatory of
this opinion. But whether the synovial membrane recedes
with these vessels, or becomes so altered in character as to
form a smooth insensitive covering to the cartilage has not yet
been determined. An amputation at the knee joint which I
performed at the Philadelphia Hospital,f before the class of the
Jefferson Medical College, gave me an opportunity of observing
the changes daily, that are produced by morbid causes in the
cartilages of the joints. From the diseased condition of the
integuments of the leg, there was a scantiness of flap for cover-
ing the stump, which left the condyles partly exposed to view.
— From round the margin of the cartilage and the place of
attachment of the crucial ligaments, in front of which the
synovial membrane passes, there was in the course of a fort-
night inflammation, secretion and a vigorous growth of granu-
lations. On the surface of the cartilage of the condyles there
appeared to be up to this time the slightest change ; it preserved
its polished shining aspect and was totally insensible to the
contact of an instrument. In the course of a few days more it

* Memoir on the non vascular tissues, Phil. Trans. 1841.
f For the details of this case see Pancoast's Operative Surgery, 2d Edit. p.
169.

BURS.E MUCOS,E. 237

lost its polish, became soft and pulpy, like a joint exposed to
maceration in a dissecting room, and melted off, flake after flake,
till the compact layer of bone covering the cells of the epfphysis
below was exposed to view. This layer was at first dark
colored, but soon became red and sensitive to the touch.
Small firm whitish conical elevations, appeared over its surface;
these grew by degrees into strong and healthy granulations, to
which the inner face of the flaps, at the end of six weeks were
firmly connected, leaving the patient a solid and serviceable
stump, upon which she is able to bear her weight with the
ordinary wooden support. The patient suffered none of the
constitutional irritation common to synovial inflammation and
it would be difficult to believe from the progress of this case,
and analogous ones reported by other surgeons, either that the
synovial membranes are spread over the cartilages of joints,
or that the cartilages themselves are vascular.

Of BurscE Mucosa.

There are certain membranous cavities called bursae mucosae
which are found between, tendons and bones, near the joints,
and in other places also, which have so strong a resemblance to
the synovial membrane, and are so intimately connected with
some of the articulations, that they ought now to be mentioned.

They are formed of a thin dense membrane, and are attached
to the surrounding parts by cellular substance ; they contain
a fluid like the synovia ; and sometimes there are masses of
fat, which, although exterior to them, appear to project into
their cavities.

There is, commonly, a thin cartilage, or tough membrane,
between them and the bone on which they are placed.

They often communicate with the cavities of joints, without
inducing any change in the state of the part.

As they are always situated between parts that move upon
each other, there is the greatest reason to believe that they are
intended to lessen friction.*

* For further information respecting this subject, as well as joints in general,
the reader is referred to a Description of the Bursac Mucosse of the Human
Body, by Alexander Monro ; to whom the world is so much indebted for the
elucidation of many important points in anatomy and physiology.

238 SUBCUTANEOUS SYNOVIAL CAPSULES.

These bursae mucosae are very numerous, as will appear
from a subsequent account of them.

Several of them are very interesting on account of their con-
nexion with very important joints.

— These bursae form synovial sheaths to the tendons, where
they run through grooves in the bones, or urtder their vaginal
ligaments, or where they glide dover each other, as in the palms
of the hands and the soles of the feet : but they are especially
met with, wherever a tendon changes its direction, and converts
a bone, a cartilage, or ligament into a pulley ; of which instances
will be detailed hereafter. When a bursae, or tendinous sheath,
invests a tendon about to subdivide, as the flexor tendons of
the fingers at the wrist, the sheath also subdivides so as to send
a process along each parting tendon ; a knowledge of which
fact is of importance to the surgeon, as this membrane when
injured, is much disposed to continuous inflammation.
— The number of these bursae vary in different individuals.
Ollivier reckons them at one hundred pairs.

Subcutaneous Synovial Capsules.

— These have been long observed about the wrist, ankle and
knee, where they sometimes attain the size of walnuts, and are
known to surgeons when enlarged by disease under the names of
ganglions and hygroma. They were studied and described for
the first time, however, by Beclard. They exist wherever the
skin is strongly and frequently moved over a resisting part : as
between the skin and the patella ; between the olecranon and
skin ; over the trochanter ; acromion ; thyroid cartilage ; at the
metacarpal and metatarsal articulations, &c. &c. They are
developed accidentally in different parts, when from any cause,
as in curvature of the spine, the friction of the tendons is in-
creased. When inflated', the cavities appear oblong and cellula-
ted, contain some synovial fluid, and look like dilated cells of
the cellular tissue, of which they are in all probability formed ;
many of them, however, are visible in the foetus during the
latter period of utero-gestation. — r

PARTICULAR ARTICULATIONS.

239

CHAPTER V.

OF PARTICULAR ARTICULATIONS.

The connexion of the Head with the Vertebra.

THE condyles of the occipital bone, and the corresponding
cavities of the atlas, are covered with cartilage. The condyle
and cavity on each side are invested with a synovial ligament,
as described in the general account of articulations.

Fig. 51.*

An anterior ligament, (liga-
mentum occipito-atloidal ante-
nor,) descends from the front
part of the great occipital fora-
men, and is inserted into all the
front part of the atlas, between
its articulating processes. That
portion of this ligament which
is in the middle, and inserted
into the tubercle of the atlas, appears stronger, and is distinct
from the rest of it.

A posterior ligament, (ligamentum occipito-atloidal pos-
terior?) passes from the posterior margin of the occipital fora-
men to the upper edge of the posterior arch of the atlas.

From each side of the upper end of the tooth-like process of
the vertebra dentata, a ligament (oblique, or moderator?)
passes upwards and outwards, to be inserted into the internal
side of the basis of each condyle of the occipital bone. There

* A posterior view of the ligaments connecting the atlas, the axis, and the
occipital bone. The posterior part of the occipital bone has been sawn away,
and the arches of the atlas and axis removed. 1. The superior part of the
occipito-axoid ligament, which has been cut away in order to show the ligaments
beneath. 2. The transverse ligaments of the atlas. 3, 4. The ascending and
descending slips of the transverse ligament, which have obtained for it the title
of cruciform ligament. 5. One of the odontoid or moderator ligaments. 6. One
of the occipito-atloid capsular ligaments. 7. One of the atlo-axoid capsular
ligaments.

240 ARTICULATIONS OF THE VERTEBRA.

is a small ligament, called the middle straight ligament (liga-
mentum medium rectum,) which passes from the tip of the
dentated process, to be inserted on the inner face of the
occipital foramen between the insertion of the moderator liga-
ments.

From the anterior margin of the great occipital foramen, a
ligament passes down on tfye inside of the vertebral cavity,
over the tooth-like process, which is inserted in the body of
the vertebra dentata, and the ligaments connected with it.
This ligament is composed of a number of fibrous bands called
by Caldani, lacerti ligamentosi. This must be dissected away
before the moderator and transverse ligaments can be brought
into view. See fig. 52. It is now more appropriately named
the occipito-axoid ligament.

Fig. 52.* There is also a ligament

which runs across from one
side of the atlas to the other,
to confine the tooth-like process
in its anterior cavity, see fig.
51, page 239, (transverse liga-
ment, ligamentum transversale
atlantis.) This ligament ad-
heres above to the occipital
bone, and below to the body of
the vertebra dentata. The anterior surface of the tooth-like
process plays on the anterior arch of the atlas ; the posterior
surface plays on this ligament. A synovial capsule is placed
on each surface of the tooth-li£e process.

— From the middle of this transverse ligament a band of fibres
extend downward to the vertebra below, giving a cruciform
arrangement to the ligament. See fig. 52.

* The upper part of the vertebral canal, opened from behind in order to show
the occipito-axoid ligament. J . The basilar portion of the sphenoid bone. 2.
Section of the occipital bone. 3. The atlas, its posterior arch removed. 4. The
axis, the posterior arch also removed. 5. The occipito-axoid ligament, rendered
prominent at its middle by the projection of the odontoid process. 6. Lateral
and capsular ligament of the occipito-atloid articulation. 7. Capsular ligament
between the articulating processes of the atlas and axis.

ARTICULATIONS OF THE VERTEBRJE. 241

The articulating surfaces of the oblique process of the atlas
and vertebra dentata on each side, are invested by a synovial
membrane. There are, also, additional ligaments placed
before and behind these processes, that have an effect on their
motions.

The uses of these different ligaments are very obvious when they are dissected.
The transverse ligament of the atlas, with the synovial membranes form an
articulation for the tooth-like process, which is of a peculiar kind. The liga-
ments that pass from this process, to the bones of the condyles of the occipital
bone, must have an effect in restraining the rotation of the head and atlas on
this process, and therefore have been called moderator ligaments.

The Articulations of the Vertebrae with each other.

To acquire a perfect idea of the construction of the Spine it is necessary to
examine, at least, two preparations of it : in one of which the bodies of the
vertebrse should be sawed off from the processes, so that the spinal canal may
be laid open.

The bodies of all the vertebrae, except the atlas, are connected
to each other by the intervertebrdl fibre-cartilaginous matter
described in page 138, which unites them very firmly, at the
same time that it allows of some motion, in consequence of its
elasticity and compressibility. This connexion is strengthened
by two ligaments, which extend the whole length of the spine,
from the second cervical vertebra to the sacrum.

The first of these, denominated the anterior vertebral
ligaments , covers a considerable part of the anterior sur-
face of the bodies of the vertebrae ; it is thickest in the middle,
and varies in its breadth in different parts of the verte-
bral column ; it adheres very firmly to the intervertebral
substance, and not so firmly to the bodies of the vertebrae.
It has the shining silver-like appearance of tendon, and seems
to consist entirely of longitudinal fibres. There are many
fibres which appear to be connected with it, that do not extend
the whole length of the spine.

On the posterior surface of the bodies of the vertebrae, in the
cavity which contains the spinal marrow, is the posterior or
internal vertebral ligament, which, like the anterior, extends
from the upper part of the spine to the sacrum.

In its progress downwards it is broader where it is in contact
21

242 ARTICULATIONS OF THE VERTEBRJE.

with the intervertebral matter, and narrower about the middle
of each of the bodies of the vertebrae. It appears to consist of
longitudinal tendinous fibres, which are similar to those of the
anterior ligament. The fibres of which these ligaments are
composed, are more closely connected by origin and insertion
with the intervertebral matter, than with the bodies of the
vertebrae. Some of the fibres are inserted into the next verte-
brae or intervertebral substance below their place of origin,
others into the second or third, and some into the fourth or
fifth.

The oblique processes of the vertebrae are covered with
cartilage, and are invested with a synovial membrane, like the
other movable articulations. In the neck and back these
membranes are thin and delicate ; but in the loins they are
blended with ligamentous fibres which give them additional
strength.

Some of the most curious and interesting ligaments of the
spine, or indeed of the body, are those which are attached to
the bony plates or arches that extend from the oblique to the
spinous processes of each vertebrae. These plates form a great
portion of the posterior part of the vertebral canal and the
vacant spaces between them are filled up by these ligaments,
which extend from the plates of each upper vertebra of those
of the next vertebra below.

They are situated between the spinal process and the oblique
processes on each side.

They are, therefore, two distinct ligaments between the two
vertebrae, one on each side of the spinal process ; and as. they
extend only from the plates or arches of one vertebra to those
of the other, they must necessarily be very short. They are
much more conspicuous on the internal surface of the vertebral
cavity than they are externally. They are thick and substantial,
and very elastic ; their color resembles that of a yellowish
adeps ; and from that circumstance they are called the yellow
or elastic ligaments. They complete the cavity for the spinal
marrow. There are twenty-three pairs in all.

As the plates or arches to which they are connected must

ARTICULATIONS OF THE VERTEBRJE. 243

recede from each other, when the spine is bent forwards, it

seems that they should be elastic.

Fig. 53.* There are also ligaments between

the spinous processes, which extend
from the under surface of one spinous
process to the upper surface of the
spinous process below it. These are
composed of tendinous shining fibres,
and are sufficiently loose to permit
the anterior flexure of the vertebral
column. From their situation they
are denominated interspinal liga-
ments.

There is also a thin and narrow ligamentous band, which
extends from the spinous process of the seventh cervical verte-
bra to the spinous processes of the os sacrum, and adheres to
the ends of the intermediate spinous processes. It is exterior
to the tendinous origins of the trapezii and latissimi dorsi
muscles. The upper portion is slightly connected to the
trapezius, the lower part adheres more firmly to the latissimus
dorsi.

The ligamentum nucha, ligament of Diemerbrcek, as it has
been denominated, is a narrow but firm strip, which extends
from the spinous process of the last cervical vertebra, to the
occipital bone, at or near its protuberance. It is very strongly
developed in all the larger quadrupeds, with pendant heads.
That portion of the trapezius muscle which is between the
occipital bone and the seventh cervical vertebra, originates
from it, or is intimately connected with it ; and a portion of the
splenius muscle is also connected with it.

From the internal surface of this ligament, a thin tendinous
membrane arises, whose fibres run obliquely upwards and

* A posterior view of a part of the thoracic portion of the vertebral column,
showing the ligaments connecting the vertebrae with each other and the ribs
with the vertebrae. 1. The supra-spinous ligament. 2, 2. The ligamenta sub-
flava, or yellow elastic ligaments, connecting the laminae. 3. The anterior costo-
transverse ligament. 4. The posterior costo-transverse ligaments.

V

244 ARTICULATION OF THE LOWER JAW.

forwards, and' are inserted into the spinous processes of each
of the cervical vertebrae above the seventh, and also into the
atlas and the os occipitis. Attached to the ligamentum nuchse
and to the spine, this membrane seems like a partition between
the muscles which lie on each side of the back of the neck.

After inspecting the different ligaments of the spine, it will be obvious- that the
yellow ligaments are among the most important of them ; in consequence of
their position, their strength) and their elasticity.

Articulation of the Lower Jaw, (Temporo maxillary.}

The glenoid cavity of the tempora4 bone with the tubercle
before it, and the condyle of the lower jaw, are covered with
cartilages. A cartilage is placed between them called inter-
articular) which being flexible, is accommodated to the con-
vexity of the condyle and hollowness of the glenoid cavity,
and also to the figure of the aforesaid tubercle to which it is
extended. A synovial capsule, or bag, invests the glenoid
cavity and the tubercle, and covers the upper surface of the
cartilage. A second capsule of the same kind is attached to
the condyle of the lower jaw, and the lower surface of the car-
tilage. A few ligamentous fibres extend from the circumfer-
ence of the cavity and tubercle of the temporal bone, over both
synovial capsules and the cartilage between them, to the lower
jaw below the condyle, and appear to be attached to the
cartilage.

These fibres are collected in such numbers, on the external
and internal sides of the articulation, that they have been called
the external and internal lateral ligaments.

Another ligament called stylo-maxillary, is mentioned which
arises from the styloid process of the temporal bone, and is in-
serted into the lower jaw near its angle ; but this seems rattier
appropriated to the stylo-glossus muscle than to this articulation.

In consequence of this structure, the condyle of the lower
jaw moves out of the glenoid cavity upon the tubercle, when
the mouth is opened widely.

ARTICULATIONS OF THE SHOULDER, 245

Articulation of the Clavicle and Sternum, called Sterno-clavicular.

The connexion of the clavicle and sternum resembles strongly
that of the lower jaw and temporal bone. A movable cartilage
is placed between the articulating surfaces, with a distinct syno-
vial capsule on each side of it, applied in the usual manner to
the corresponding surface of the clavicle and of the sternum.
Exterior to these capsules and the intervening cartilage, are
many ligamentous fibres, which are most numerous on the ante-
rior and posterior surfaces, but diverge from each other as they
proceed from the clavicle to the sternum, and are, therefore,
called Radiated Ligaments.

There is a strong ligament called the Inter clavicular, which
passes across the sternum internally, from one clavicle to the
other.

And another ligament, which arises from the inferior rough
surface of the clavicle, near the sternum, which is inserted into
the cartilage of the first rib.

This is called the Rhomboid, or Costo-clavicular ligament.

Articulations of the Clavicle and Scapula, (Scapulo-clamcular.)

Fig. 54.* These are two in number ;

one which connects the acro-
mion and external end of the
clavicle called acromio-clavicu-
lar, and one which connects
the lower surface of the outer
part of the clavicle with the
coracoid process of the scapula,
called coraco-Clavicular.
Acromio-clavicular. The small surfaces of the clavicle and
scapula, which are in contact with each other, are furnished

* The ligaments of the sterno-clavicular and costo- sternal articulations. 1.
The anterior sterno-clavicular ligament. 2. The inter-clavicular ligament. 3.
The costo-clavicular or rhomboid ligament, seen on both sides. 4. The inter-
articular fibro-cartilage, brought into view by the removal of the anterior and
posterior ligaments. 5. The anterior costo-sternal ligaments of the first and
second ribs.

21*

246 ARTICULATIONS OF THE SHOULDER.

with the apparatus of a movable articulation. They are
covered with cartilage, and are invested with a small synovial
capsule. The upper and lower surfaces of the extremities of
the clavicle and acromion are covered by a ligamentous mem-
brane, which is called, from its situation, the superior and infe-
rior ligament of this articulation.

Coraco-clavicular, consisting of two portions, conoid and trape-
zoid. But these bones are more firmly connected by the liga-
ment which passes to the coracoid process of the scapula from
the under side of the clavicle, and is very strong. ISome of tne
fibres which compose this ligament are so arranged that they
have the appearance of an inverted cone : the remaining fibres
appear like another ligament, and therefore they have been
called the trapezoid and conoid ligaments.

— The base of the conoid ligament is upwards, and its apex
or origin is at the root of the coracoid process. It is the stronger
of the two. The trapezoid is at the outer side of the conoid.
It is broad and thin, with its fibres separated by interstices. It
rises from the root of the coracoid process, 'and is inserted on an
oblique ridge, leading from the tubercle of the clavicle to its
acromial end. —

By their situation and strength they are enabled to retain the
bones in their proper relative positions, at the same time that
they permit a peculiar rotary motion.

— There is a bifid ligament called Kgamentum bicorne, arising
from the root of the coracoid process, at the inner side of the
conoid, which runs inwards in front of the subclavius muscle,
to which it serves as a fascia, and bifurcates ; one horn is
attached to the under surface of the clavicle near the rhomboid
ligament, and the other to the end of the first rib, under the
tendon of the subclavius muscle. —

^Articulation of the Os Humeri and Scapula, (Scapulo-humeral.)

The spherical portion of the upper extremity of the os humeri
is the part of that bone which is principally concerned in the
articulation, and is covered with cartilage ; as is also the glenoid
-cavity of the scapula.

ARTICULATIONS OF THE SHOULDER.

247

Fig. 55.* The glenoid cavity of the scapula,

which is so small in the dried bone",
when compared with the head of
the os humeri, is enlarged lay the
long tendon of the biceps muscle,
which is attached to the upper edge
of its margin, and then divides and
passes down on each side of the
cavity, increasing the breadth of it
considerably, thus forming what is
called iheglenoid ligament, deepen-
ing the socket, and giving greater
latitude of motion to the arm, from its
elasticity, than if the socket had all
been formed of bone. It appears to be blended with the carti-
lage that lines the cavity, and also with the capsular ligament
which is exterior to it.

The .articulating surface, thus composed, is perfectly regular
and uniform.

The synovial , ligament, in this articulation, is so blended
with an external stronger ligament, that it cannot be separated
in the recent subject ; but, notwithstanding, it is applied to the
articulating surfaces in the same way that it is applied to the
other joints forming a capsule. The stronger exterior lamina
is, of course, only applied to that part of the synovial capsule
which proceeds from the margin of one cartilaginous articulating
surface to the other : it appears to be most intimately connected
with the periosteum, and is rendered more firm and thick in
particular parts, by the addition of fibres from the tendons of the
supra and infra-spinatus, and subscapularis 'muscles with which
it is blended.

It arises from the scapula at a small distance from the mar-

* The ligaments of the scapula and shoulder joint. 1. The superior acromio-
clavicular ligament. 2. The coraco-clavicular ligament ; this aspect of the
ligament is named trapezoid. 3. The coraco-acromial ligament. 4. Coracoid
or transverse ligament as it is sometimes called. 5. Capsular ligament. 6.
Coraco-humeral ligament. 7. The long tendons of the biceps issuing from the
capsular ligament, and entering the bicipital groove.

248 ARTICULATION OF THE ELBOW.

gin or edge of the glenoid cavity, as formed by the tendon of
the biceps, and is inserted into the os humeri at a small distance
from the edge of the cartilaginous articulating surface ; and, if
dissected away from the bones, would appear like a cylindrical
bag with both extremities open. — The capsular ligament is
thickened in front by a band of fibres, arising from the outer part
of the back surface of the coracoid process, which proceeds
beneath the triangular ligament to the upper part of the os
humeri ; it is closely blended with, and forms a part of the cap-
sular ligament, and is denominated tbe coraco-humeral ligament,
or ligamentum adscititium. —

The long tendon of the biceps muscle, in the groove at the
head of the os humeri, appears to penetrate this ligament ; but
it is not within the cavity of the synovial membrane ; for this
membrane sends down a process like the finger of a glove,
which lines the groove, and is reflected from its surface upon
the surface of the tendon, and covers it during its whole extent,
being reflected from the tendon, at its upper termination, to the
adjoining surface ; so that the tendon is in fact outside of the
synovial capsule, which, therefore, confines the synovia com-
pletely.

This capsular ligament, which is one of the strongest, would
not avail much in keeping the bones in their proper situations,
if the muscles and their tendons were not disposed in such a
manner, that when the muscles act, their power is excited to
the same effect. In some cases of paralytic affection, where
the muscles exert no influence, the weight of the arm, when it
is allowed to hang without support, draws the head of the os
humeri, below the glenoid cavity, notwithstanding the capsu-
lar ligament. At tfce same time it ought to be observed, that
this ligament must be lacerated in every case of complete
luxation of the os humeri ; as it cannot possibly distend suffi-
ciently to permit the separation of the bones to the extent which
then takes place.

The Articulation of the Elbow.

Those surfaces of the os humeri, ulna, and radius, which move
upon each other, are covered with cartilage.

ARTICULATION OF THE WRIST.

249

Fig. 56.* The motion of the ulna and radius on the

os humeri is that of the simple flexion and
extension. The cylindrical head of the Radius
performs a part of a revolution, nearly on its
own axis, without moving from the depression
in the side of the ulna, with which it is in
contact.

The synovial membrane adheres very firmly
to the surface covered with cartilage on each
of the bones, and is reflected from the margin
of this surface, on one bone, to that of the
others. As the principal motion performed is
hinge-like, the principal ligaments are on the
sides. There is also a circular ligament, which
arises from the ulna and invests the narrow part
of the radius immediately below its cylindrical
head like a loop, to confine the radius in
contact with the ulna, and at the same time
permit its motion.

This ligament is so blended with the synovial membrane, that
it sometimes cannot be separated from it.

The lateral ligaments are denominated from their origin and
insertion, Brachio-radial, and Brachio-cubital, or External and
Internal. The external is a strong, narrow band, attached
above to the external condyle of the humerus, and below
to the orbicular ligament, and adjoining ridge of the ulna.
The internal, is thick and triangular ; its apex is attached to
the internal condyle of the humerus, and its lower or broad
part is inserted into the margin of the greater sigmoid fossa of
the ulna extending from the coronoid process to the olecra-
non. — Posterior to it runs the ulnar nerve. The ligament
which invests the neck of the radius is called Coronary or
Orbicular.

* An internal view of the ligaments of the elbow joint. 1. The anterior
ligament. 2. The internal lateral ligament. 3. The orbicular ligament. 4. The
oblique ligament. 5. The interosseous ligament. 6. The internal condyle of
ihe humerus, which conceals the posterior ligament.

250

ARTICULATION OF THE WRIST.

— The orbicular ligament is a firm band
Fig. 57.* several lines in breadth, which surrounds
the head of the radius, and is attached by
each end to the extremities of the lesser sig-
moid cavity. It is strongest behind where it
receives the external lateral ligament. — On its
inner surface it is lined by a process of syno-
vial membrane from the elbow joint. — When
this ligament is ruptured, as often occurs in
children, the head of the radius readily slips
from its place. —

There are also some ligamentous bands,
which run upon the front and back parts of
the joint to strengthen it, which are called
Anterior and Posterior accessory ligaments. —
They are broad thin membranous layers
placed on the outer surface of the synovial
membrane, and are both attached to the hume-
rus above, and upon the sides to the lateral
ligaments : below the posterior is attached to
the olecranon ; the anterior to the coronoid process of the
ulna and to the lateral ligament. Within the synovial mem-
brane, in the upper margins of the depressions for the olecranon
and coronoid processes of the ulna, are the adipose substances
usually found in joints.

Articulation of the Wrist.

The structure of the wrist is particularly complex, because it consists of three
articulations, which are contiguous to each other, viz. That of the ulna and
radius; of the radius and first row of carpal bones, radio-carpal; and of the
first and second row of carpal bones with each other, middle carpal joint.

An oblong convex head is formed by the upper surfaces of
the scaphoides and lunare, and a portion of the upper surface

* External view of the elbow joint. 1. Humerus. 2. Ulna. 3. Radius. 4.
The external lateral ligament inserted below into the orbicular ligament. 6.
The posterior extremity of the orbicular or coronary ligament, spreading out at
its insertion into the ulna. 7. The anterior ligament, scarcely seen in this view
of the articulation. 8. The posterior ligament, thrown into folds by the exten-
sion of the joint.

ARTICULATION OF THE WRIST.

251

of the cuneiforme bone. This head is covered by one cartilage,
which is so uniform that the different bones cannot be distin-
guished from each other. The lower end of the radius i^ arti-
culated with this head, but does not cover the whole of it ; a
portion of this head, therefore, is under the ulna, but not in
contact with that bone : for the cartilage which lines the con-
cavity of the radius, is continued beyond the radius, so as to
cover the remainder of the head, formed by the carpal bones.

Fig. 58.* — This cartilage which is extended

from that covering the radius, is
attached to a depression on the
inner surface of the styloid pro-
cess of the ulna. It is called the
inter-articular or from its shape the
triangular fibro-cartilage. The sy-
novial membrane forming the joint
between this cartilage and the end
of the ulna is loose and is called the
sacciform membrane, (see fig. 58.)
The lower end of the ulna is in
contact with the upper surface of
this cartilage, and is articulated lat-
erally with the semilunar cavity of
the radius. This semilunar cavity

* A careful dissection being made, the ligaments of the carpus will appear
as seen in this and the following figures. —

Dorsal surface, a. External lateral ligament. It runs from the styloid process
of radius to os scaphoides. b. Internal lateral ligament which runs from the
styloid process of the ulna and divides into two fasciculi, one of which is attached
to the pisiform, the other to the cuneiforme bone. d. Posterior or dorsal ligament
of the radio-carpal articulation. They are thin and weak and run from the
radius to the first row of bones, g. Posterior radio ulnar ligament. ». A pos-
terior or dorsal thin band of fibres, which connects the two rows of bones
together. L "Dorsal ligaments, which connect the metacarpal bones together at
their base. n. Dorsal ligament connecting the anterior ends of these bones.
o. A middle dorsal ligament stretched from the second metacarpal bone to the
trapezoid. p. An external ligament running from this bone to the trapezium;
another internal one running from this bone to the os magnum, is not here seen.
r. An oblique ligament, running from the os unciforme to the third metacarpal
bone. s. Capsular ligament of the metacarpo-carpal articulation of the thumb.
t. A sort of capsular ligament of the metacarpo-carpal joint of the little finger.
n. The place of dorsal ligament supplied in a great measure by extensor tendon.
z. Lateral ligament.

252

ARTICULATION OF THE WRIST.

is lined by a cartilaginous process, continued from the upper
surface of the aforesaid cartilage ; so that the extremity and
the side of the ulna play upon the cartilage continued from the
radius. This articulation of the ulna and radius is distinct from
that of the radius and carpus.

Fig. 59.* A synovial membrane covers the

•articulating head formed by the
three bones of the carpus, and is
reflected from the margin of their
cartilaginous surface, to the carti-
lage at the end of the radius. A
plait or fold of this membrane
passes from the head of the carpus,
at tile junction of the scaphoides
and lunare, to the opposite part of
the cartilage of the radius, and has
been called the Mucous Ligament,
(ligamentum mucosum.)

A strong ligament (internal lat-
eral) is placed on the internal side .
of this articulation, which arises
from the styloid process of the ulna, and is inserted into the
anterior transverse ligament which confines the flexor tendons,
and into the pisiforme and cuneiforme bones.

* Anterior or palmar surface, a. External lateral ligament, b. Internal
lateral ligament, c. Three anterior or palmar ligaments belonging to the articu-
lation of the first row of bones with the radius, or the radio-carpal articulation.
They run from the radius to the bones of the carpus, e. Two very strong
inferior ligaments which connect the pisiform and cuneiform bones together :
besides these, four other ligaments are discovered at this articulation; an exter-
nal, an internal, and two lateral. So strong is this articulation, that the pisiform
bone is rarely if ever dislocated. /. Anterior radio-lunar ligament. Articula-
tion of the two bones together. I. An anterior or palmar ligament, running
from the os magnum, and diverging to the three inner bones of the first row.
m. Palmar ligaments which connect the metacarpal bones at their base. There
is another set of fibres called the interosseous, not seen here, which connect
these bones at their base. n. Palmar or transverse ligament at the anterior end
of these bones, s. Capsular ligament of the thumb, u. Ligamento-cartilagi-
nous, thickens over the first joint of the fingers, v. Lateral ligaments, y. Pal-
mar or glenoid ligaments, as they seem to deepen the articular surface for the
phalanges.

ARTICULATION OF THE WRIST.

253

Fig. 60.*

Another ligament, (external lateral,) on the external side,
arises from the styloid process of the radius, and is inserted into
the scaphoides, some of its fibres being continued int6 the
aforesaid transverse ligament, and the trapezium.

There are two broad irregular ligamentous membranes : one
of which arises from the anterior margin of the articulating
surface of the radius ; and the other from the posterior margin.
One of them is inserted anteriorly, and the other posteriorly,
into the margin of the corresponding surface of the scaphoides,
lunare and cuneiforme. They adhere to the synovial membrane ;
but in some places this membrane appears through apertures
which are in them.

The surfaces, by which the
first and second rows of carpal
bones are articulated with each
other, are very irregular. The
magnum and part of the unci-
forme form a prominent oblong
head ; on each side of which is
a much lower surface, formed
by the trapezium and trapezoides
externally, and the remaining por-
tion of the unciforme internally ,f
The scaphoides, lunare, and
cuneiforme, form a cavity which
corresponds with this head, and
also with the lower surface

* A diagram showing the disposition of the five synovial membranes of the
wrist joint. 1. The sacciform membrane. 2. The second synovial membrane.
3, 3. The third, or large synovial membrane. 4. The synovial membrane be-
tween, the pisiform bone and the cuneiforme. 5. The synovial membrane of
the metacarpal articulation of the thumb. 6. The lower extremity. of the radius.
7. The lower extremity of the ulna. 8. The interarticular fibro-cartilage. S.
The scaphoid bone. L. The semilunare. C. The cuneiforme ; the interosseous
ligaments are seen passing between those three bones and separating the articu-
lation of the wrist (2) from the articulation of the carpal bones (3). P. The
pisiforme. T. The trapezium. 2T. The trapezoides. M. The os magnum.
U. The unciforme; interosseous ligaments are seen connecting the os magnum
with the trapezoides and unciforme. 9. The base of the metacarpal bone of the
thumb. 10, 10. The bases of the other metacarpal bones.

f The palm of the hand is supposed to present forward.
22

254 ARTICULATION OF THE CARPAL BONES.

formed by the unciforme ; while another surface of the sea-
phoides is articulated with the trapezium and trapezoides.
These corresponding surfaces, formed by the two rows of carpal
bones, irregular as they are, compose but one articulation,
which is capable of a limited flexion and extension. It has a
synovial membrane, with two lateral ligaments, and an
anterior and posterior ligament ; these last, however, are short,
and can be best examined from within, by cutting open the
articulation.

The bones of each row move laterally upon each other.
Their lateral surfaces, which are in contact, are covered with
cartilage ; and the synovial sac which exists between the first
and second row of bones, sends off processes between these
surfaces, which are disposed like the ordinary synovial mem-
branes in other articulations ; adhering, as is supposed, to each
of the cartilaginous surfaces, while they communicate with the
larger cavity between the two rows.

— Interosseous ligaments pass between the three outer bones
of the upper row, and the three inner of the lower so as to
intercept at these points the distribution of the synovial mem-
branes between the individual bones of each row. By this
means there is, as seen in fig. 60, including the sacciform mem-
brane, five synovial membranes in the wrist joint.

Articulation of the Carpal and Metacarpal Bones.

The metacarpal bones are connected to the last row of the
carpus by surfaces which are covered with cartilages, and
supplied with synovial membranes, as the most movable
articulations are ; but the ligaments which connect these bones
do not permit much motion between them. The ligaments
are all dorsal and palmar. The irregularity of the articulating
surfaces of the metacarpal bones of the index and middle finger
also contribute to restrain their motion ; and these bones accord-
ingly move less than the other two metacarpal bones, whose
surfaces are better adapted for motion.

ARTICULATION OF THE RIBS. 255

Articulation of the Fingers.

The first joint of the fingers has a large synovial membrane,
which invests the head of the metacarpal bone and the corres-
ponding cavities of the bones of the first phalanx. On each
side is a strong lateral ligament, which arise from the side of the
head of the metacarpal bone, and is inserted into the side of the
base of the first phalanx.

Anteriorly there is also a ligament, which, although thick
and strong, is very flexible. It is thickened by cartilaginous
matter on its palmar face, which serves as a sort of pulley to the
tendons, and increases their power by removing them from their
line of action. Posteriorly the expansion of the tendons of the
extensor muscle, and the tendons of the interossei, have the
effect of a ligament.

The different phalanges are articulated with each other in a
similar manner. The lateral ligaments are very strong : the
tendon of the extensor covers the articulation posteriorly ; and
anteriorly, under the flexor tendons, there is a soft, but thick
ligamentous substance. The metacarpal bone of the thumb
differs greatly from the other metacarpal bones in its articulation
with the wrist, as respects its motions. The articulating surfaces
are calculated for lateral motion as well as flexion and exten-
sion ; and there are no ligaments which prevent it. Its capsular
ligament forms a complete sac. The first joint of the thumb
resembles considerably that of the fingers ; and the second joint
resembles the last of the phalanges.

Articulation of the Ribs.

The ribs are connected to the bodies of the vertebrae and the
intervertebral cartilages, by one articulation, and to the trans-
verse processes of the vertebrae by another : these articulations
have the ordinary apparatus for motion, with capsular ligaments,
which in one caserpass from the heads of the ribs to the bodies
of the vertebrae, and in the other from the tubercles to the trans-
verse processes. These form what are called the costo-vertebral,
and costo-transverse articulations.

256 ARTICULATION OF THE RIBS.

Fig. 61.* — The capsular ligament of

the costo-vertebral articulation,
is not complete. It is much
thickest in front and upon the
sides, and radiates from its origin
on the head of the ribs, whence
it is usually called the anterior
radiating or stellate ligament.
— There is also a small inter-
articulating ligament, in this

articulation, which passes from a ridge on the head of the rib to
a corresponding line on the intervertebral substance. It thus
divides the joint into two halves, each of which has a separate
synovial membrane. This ligament does not exist where the
ribs are attached to a single vertebra, as the first, eleventh and
twelfth.

— The costo-transverse articulation, besides its feeble capsular
ligament and synovial membrane connecting the tubercle of the
rib with the facet of the transverse process, includes three other
ligaments, the internal transverse, the external transverse, and
the middle costo-transverse.

— The internal transverse, arises from the inferior margin of the
transverse process, and is inserted into the upper margin of the
neck of the rib below.

— The external transverse, arises from the extremity of the
transverse process, and is inserted into the corresponding rib, just
beyond the tubercle.

— The middle costo-transverse ligament is extended between the
neck of the rib and the contiguous transverse process. To be
well seen it is necessary to saw longitudinally through the neck
of the rib and its transverse process.

These ligaments permit the motions necessary for respiration,
and restrain all others.

* The anterior ligaments of the vertebrae, and ligaments of the ribs. 1. The
anterior common ligament. 2. The anterior costo-vertebral or stellate ligament.
3. The anterior costo-transverse ligament. 4. The inter-articular ligament con-
necting the head of the rib to the intervertebral substance, and separating the
two synovial membranes of this articulation.

HIP JOINT.

257

The connexion of the ribs anteriorly with their cartilages, is
such as admits of no motion whatever between them ; but the
extremities of the cartilages are articulated with the sternum, at
the pits on the edges of that bone.' In many instances there is
no appearance of synovia between the ends of the cartilages and
the sternum ; but this fluid is mostly to be found in the pits, on
the lower extremity of the sternum.

— In the articulations between the cartilages of the ribs and
the sternum, there is a synovial membrane, and two ligaments,
anterior and posterior. These radiate from the sternal end of
the cartilage, one over the anterior, the other over the posterior
face of the sternum, and are blended with its periosteum, see
fig. 54, p. 245.—

The Hip Joint.

Fig. 62.* The acetabulum is lined

with cartilage ; and the
brim or margin of it is
much enlarged, and the
cgvity deepened, by the
addition of fibro-cartilagi-
nous matter, which forms
a regular smooth edge.
This cartilaginous ring is
continued across the upper
part of the notch in the
acetabulum ; so that it com-
pletes the circular margin
of the cavity, but leaves
the under part of the notch
open. This forms what is

called the cotyloid ligament. The head of the os femoris is
covered with cartilage, but the depression in it is still visible.

* The ligaments of the pelvis and hip-joint. 1. The lower part of the
anterior common ligament of the vertebrae, extending downwards over the front
of the sacrum. 2. The lumbo-sacral ligament. 3. The lumbo-iliac ligament.
4. The anterior sacro-iliac ligaments. 5. The obturator membrane. 6. Pouparl's
ligament. 7. Gimbernat's ligament. 8. The capsular ligament of the hip-joint.
9. The ilio-femoral or accessory ligament.

22*

258 HIP JOINT.

From this depression a strong round ligametit (ligament-urn teres
or rotundum) see fig. 71, p. 270, arises, which appears to pass
into the depression, near the centre of the acetabulum ; but
actually terminates in the lower edge of the cartilaginous ring
or margin, where it crosses over the notch, and not in the bone.
This ligament is in fact divided into two parts at its insertion ',
one passes out at the inferior .part of the cotyloid notch and is
inserted on the margin of the ischium ; the other runs to the
superior end of the notch, and besides being blended with the
cotyloid ligament, is attached to the margin of the acetabulum.
The thin (synovial) membrane with which this ligament is
invested extends to the centre of the acetabulum, and has given
rise to the opinion that the ligament was inserted in the bottom
of the acetabulum.*

This ligament allows the head of the os femoris to rise out of
the acetabulum, but it is probably torn in every luxation of the
os femoris.

The capsular ligament, which contains these articulating
parts, is the strongest in the body. It arises around the aceta-
bulum, near the basis of the cartilaginous brim, but it does not
adhere to the cartilaginous edge ; and it is inserted into the os
femoris, near the roots of the trochanters^sb that it includes a
large portion of the neck of the bone. It is not every where of
the same thickness and strength ; for, in various places, there
are additional ligamentous fibres. The largest portion of these
additional fibres appears to arise from the inferior anterior spinous
process of the ilium. The capsular ligament is thinest at its
internal and posterior part. — The additional fibres which arise
from the anterior inferior spinous process of the ilium constitute
the ilio-femoral, or accessory ligament.

The synovial membrane forms the internal lamina of this
ligament: it invests the articulating surfaces in the usual manner,
and being reflected from the internal surface of the capsular
ligament to the neck of the os femoris, it is in the place of
periosteum to that part of the bone.

It seems probable that this membrane is so reflected and

* See motions of skeleton.

^Jtejf. <*~r ^t-"«" "

ARTICULATION OF THE KNEE.

arranged, that the internal Jgament is covered by it also, and
of course, that this ligament is exterior to the synovial mem-
brane, j

There is a considerable quantity of adipose matter near the
termination of the aforesaid internal ligament, which is also
exterior to the synovial membrane : some of this can be pressed
out of the acetabulum, at the vacuity in the notch under the car-
tilaginous margin.

Articulation of the Knee.

The synovial membrane of the knee joint is, in some places,
without the support of a proper capsular ligament, or external
lamen, so that it is easier distinguished in this articulation than
in many others.

Fig. 63.* It adheres firmly to the cartilaginous sur-.
faces of the os femoris, tibia, and patella,
and is reflected in the usual manner from
one to the other of these surfaces. It
arises closely from the edge of the cartilagi-
nous surface at the top of the tibia ; but on
the anterior part of the os femoris, it is
continued to some distance from the mar-
gin of the pulley-like surface, and the edges
of the condyles. On each of the portions
of the cartilagindus surfaces of the tibia is
a cartilage of a semilunar form, so placed
that its convex edge rests on the margin of the cartilaginous
surface, and its concave edge is internal. These cartilages are

* The right knee joint laid open from the front, in order to show the internal
ligaments. 1. The cartilaginous surface of the lower extremity of the femur
with its two condyles; the figure 5 rests upon the external ; the figure 3 upon
the internal condyle. 2. The anterior crucial ligament. 3. The posterior crucial
ligament. 4. The transverse ligament. 5. The attachment of the ligamentum
mucosum ; the rest has been removed. 6. The internal semi-lunar fibro-carti-
lage. 7. The external fibro-cartilage. 8. A part of the ligamentum patellae
turned down. 9. The bursa, situated between the ligamentum patellae and the
head of the tibia. It has been laid open. 10. The anterior superior tibio-nbular
ligament. 10. The upper part of the interosseous membrane ; the opening
above this membrane is for the passage of the anterior tibial artery.

260

ARTICULATION OF THE KNEE.

thick at their external, and very thin at their internal edges ; so
that they form two superficial concavities on the top of the
tibia.

Their extremities are attached by ligaments to the central
protuberance of the tibia, and their anterior extremities are also
connected by a ligament to each other.

The synovial membrane is §o reflected as to cover the whole
Fig. 64.* surface of these cartilages, except the
exterior edge, which is connected with the
external ligaments of the articulation.

The use of these cartilages, is evidently
to form concavities on the top of the tibia,
for accommodating the condyles of the os
femoris ; and upon examination, they
will not appear so anomalous as they do
at first view, for there is a considerable
analogy between them and the cartilagi-
nous edges of the glenoid cavity and of the
acetabulum. These are called the semi-
lunar cartilages. The internal is but little
more than a semicircle ; the external is nearly circular in its
shape.

The patella appears to project into the cavity of the joint,

* A longitudinal section of the left knee joint, showing the reflections of its
synovial membrane. 1. The cancerous structure of the lower part of the femur.
2. The tendon of the extensor musclesof the leg. 3. The patella. 4. The liga-
mentum patellae. 5. The cancellous structure of the head of the tibia. 6. A
bursa situated between the ligamentum patellae and the head of the tibia. 7.
The mass of fat projecting into the cavity of the joint below the patella. * *
The synovial membrane. 8. The pouch of synovial membrane which ascends
between the tendon of the extensor muscles of the leg, and the front of the
lower extremity of the femur. 9. One of the alar ligaments j the other has
been removed with the opposite section. 10. The ligamentum mucosum left
entire ; the section being made to its inner side. 11. The anterior or external
crucial ligament. 12. The posterior ligament. The scheme of the synovial
membrane which is here presented to the student, is divested of all unnecessary
complications. It may be traced from the saculus (at 8), along the inner sur-
face of the patella ; then over the adipose mass (7) from which it throws off the
mucous ligament (10) ; then over the head of the tibia, forming a sheath to the
crucial ligaments ; thea upwards along the posterior ligament and condyles of
the femur, to the sacculus whence its examination commenced.

KNEE JOINT. 261

and its internal surface is very prominent ; around the margin
of this surface, and especially at the under part of it, the adi-
Fig. 65.* pose substance found in joints is very^abun-
dant. On each side of the adipose mass,
under the patella, is a plait of the synovial
membrane, called ligamentum alare minus,
and majus ; and a process of the mem-
brane, called ligamentum mucosum passes
from the neighborhood of the adipose
mass to the os femoris between the con-
dyles.

These processes retain the adipose sub-
stance in its proper place, during the motions
of the joint.

There are two very strong ligaments, called the anterior and
posterior crucial, which arise from the middle protuberance of
the tibia, one of which is inserted posteriorly into the corner face
of the external condyle of the os femoris, and the other, into
the outer face of the internal. These ligaments decussate each
other partially, on which account the name crucial is applied to
them. They are in a state of tension when the leg is extended,
and prevent it from moving farther forward : when it is bended
they are relaxed. They add greatly to the strength of the
connexion between the os femoris and tibia.

These ligaments are generally supposed to be in the cavity of
the joint ; but the synovial membrane is reflected round them in
such a manner that they are exterior to it.

In addition to the crucial ligaments, this articulation has the
following external supports.

When the leg is extended, these ligaments are tense, they*
therefore prevent rotation in the extended state: when the

* Posterior view of the ligaments of the knee joint. 1. Posterior ligament of
"Winslow, connected by a tendinous expansion with 2, the tendon of the semi-
membranous muscle ; the latter is cut short. 3. The process of the tendon,
which spreads out in the fascia of the popliteus muscle. 4. A process which is
sent inwards beneath the internal lateral ligament. 5. The posterior part of the
internal lateral ligament. 6. The long external lateral ligament. 7. Short ex-
ternal lateral ligament. 8. Tendon of popliteus cut short. 9. The posterior
superior tibio-fibular ligament.

" ^

/

262 KNEE JOINT.

leg is bent, they are relaxed, and, therefore, admit of that
motion.

1. Two strong lateral ligaments, one on each side of the knee ;
the external of which arises from the tubercle above the external
condyle of the os fernoris, and is attached to the fibula a little
below its head ; and the internal, from the upper part and
tubercle of the internal condyle, and is inserted into the upper
and inner part of the tibia.

2. The posterior ligament or ligament of Winslow, whose
fibres run obliquely from the external condyle to the back part
of the internal side of the head of the tibia. This ligament also
prevents the leg from being drawn too far forwards.

3. The connexion of the tendons of the extensor muscles of
the leg, with this articulation, has a great effect upon it. Their
insertion into the patella places them in the situation of the
upper part of the anterior ligament, of which the very strong
ligament, that passes from the lower margin of the patella to the
tubercle of the tibia, is only the lower portion ; while the patella
may be considered as an inducted part of the ligament. The
tendons of the ham-string muscles, also, serve to strengthen the
articulation on the back and sides.

Fig. 66.* — The fascia lata of the thigh as it passes
down upon the leg, is thickened by a pro-
cess of the extensor tendons, and forms a
strong external investment or involucrum
to the knee joint. It constitutes in fact a
sort of capsular ligament to the joint ; it
closely embraces the patella and its liga-
ments, covers in and is partly blended with
the lateral ligaments, and is firmly attached
to the condyles. At the posterior part of
the joint, it forms a thin membrane, and
can scarcely be traced. Its place is there

* The anterior view of the ligaments of the knee joint. 1. The tendon of
the quadriceps extensor muscle of the leg. 2. The patella. 3. The anterior
ligament, or ligamentum patellae, near its insertion. 4, 4. The synovial mem-
brane. 5. The internal lateral ligament. 6. The long external lateral ligament,
7. The anterior superior tibio-fibular ligament

ARTICULATION OF THE TIBIA AND FIBULA. 263

supplied by the posterior ligament. On either side of the liga-
ment of the patella its inner face is in contact with the synovial
membrane of the joint. — ;

Bursa Mucosa.

There are two of these in connection with the ligamentum
patellae ; one of which is placed superficially between the
ligament and the fascia lata. This is the seafrof the enlargement
by increase of secretion, known under the name of housemaid's
knee. The other is placed between the tibia and the ligamentum
patellae, as seen in fig. 66.

Articulation of the Tibia and Fibula. — Superior Articulution.

The surfaces of the upper extremities of the tibia and fibula,
which are articulated with each other, are very small. When
the bones are in their natural position, these surfaces are nearly
horizontal, that of the tibia looking down, and that of the fibula
looking up : they are covered with cartilages, and have a syno-
vial membrane. This articulation is supported by some liga-
mentous fibres, which have been called anterior superior, and
posterior superior ligaments ; it is strengthened also by the
external lateral ligament of the knee, and by the tendon of the
biceps muscle which is inserted into the upper end of the
fibula.

Inferior Articulation.

At their lower extremities, the cartilaginous crust, which, on
each of them, forms part of the articulating surface with the
astragalous, is turned up on their lateral surfaces which are in
contact with each other ; so that a small portion (equal in
breadth only to one sixth of an inch) of the contiguous surfaces,
is covered with cartilage ; the other parts of these surfaces
which are very considerable, are attached to each other by the
intervention of fibrous or membranous matter, and there is
very little motion of the bones on each other.

There are very strong external ligaments, called the anterior

ANKLE JOINT.

inferior , and posterior inferior, which connect
the fibula to the tibia ; and from the posterior
surface of the end of the fibula, a ligament
called the transverse, passes to the posterior
part of the internal malleolus, which resembles
the marginal ligament of the glenoid cavity
and acetabulum ; for it enlarges the articulation
with the astragalus, while it serves as a liga-
ment to the tibia and fibula. There are some
short, strong fibres passing below and between
the opposite surfaces of the tibia and fibia,
called the inferior interosseous ligament. '

Articulation of the Leg, Foot, and Ankle Joint.

It should be observed that the tibia and fibula are so firmly
connected with each other below, that they may be considered
as forming but one member of this articulation.

Fig. 68.f The varied surfaces formed by

the tibia and fibula and their two
malleolar processes, and by the as-
tragalus with its two lateral facets,
where it is contiguous to them, are
invested with the usual apparatus of
articulation. The synovial fluid is
generally observed to be very redun-
dant in this joint. There are four
ligaments which enter into this ar-
ticulation.
A triangular band of fibres called the internal lateral liga-

* A posterior view of the ankle joint. 1. The lower part of the interosseous
membrane. 2. The posterior inferior ligament connecting the tibia and fibula.
3. The transverse ligament. 4. The internal lateral ligament. 5. The posterior
fasciculus of the external lateral ligament. 6. The middle fasciculus of the
external lateral ligament. 7. The synovial membrane of the ankle joint.
8. The os calcis.

f An internal view of the ankle joint. 1. The internal malleolus of the tibia.
2, 2. Part of the astragalus ; the rest is concealed by the ligaments. 3. The os
calcis. 4. The scaphoid bone. 5. The internal cuneiforme bone. 6. The inter-
nal lateral or deltoid ligament. 7. The anterior ligament. 8. The tendo Achillis ;
a small bursa is seen interposed between this tendon and the tuberosity of the
os calcis.

ARTICULATION OF THE ASTRAGALUS AND OS CALCIS. 265

ment passes downwards from the tibia at the internal malleolus,
and is inserted into the inside of the astragalus, and also into
the os calcis and naviculare. Some of the fibres are blended
with those of the sheath for the tendon of the flexor communis ;
and some of them have a radiated arrangement, in consequence
of which this has been called the deltoid ligament.

From the fibula three ligaments arise, spoken of collectively
as one ligament, external lateral, (ligament-urn triquetrum.)
The middle fasciculus, which is strong and thick, passes down-
wards from the end of that bone, to be inserted into the outside
of the os calcis. The anterior fasciculus passes forwards, and
is attached to the astragalus. The posterior fasciculus passes
backwards, and is attached to the posterior part of the astragalus.
—The anterior ligament is a thin membranous layer, in contact
with the synovial membrane, it passes from the anterior margin
of the tibia and is inserted into the anterior portion of the astra-
galus, near the articular surface. No well marked posterior liga-
ment exists at this articulation. The transverse ligament sup-
plies its place.

Articulation of the Astragalus and Os Calcis.

Fig. 69.* The astragalus is attached firmly to

the* os calcis by very strong and
short ligamentous fibres, which arise
from the fossa on its under surface,
and are inserted into the fossa Be-
tween the upper articulating sur-
faces of the os calcis. This is called
the interosseous. This ligament
separates the posterior articulations
of the astragalus and os calcis from
the anterior. The posterior articulation has a synovial mem-
brane exclusively appropriated to it. The anterior articulation

* An external view of the ankle joint. 1. The tibia. 2. External malleolus
of the fibula. 3, 3. Astragalus. 4. Os calcis. 5. Cuboid bone. 6. The ante-
rior fasciculus of the external lateral ligament attached to the astragalus. 7. Its
middle fasciculus attached to the os calcis. 8. Its posterior fasciculus attached
to the astragalus. 9. The anterior ligament of the ankle.
23

266

ARTICULATION OF THE TARSAL BONES.

is supplied by an extension of the membrane which invests the
articulating surfaces of the astragalus and naviculare.

The connexion of the astragalus, with the os calcis is sup-
ported by the lateral ligaments of the ankle joint, and also by
many irregular ligamentous fibres.

Articulation of the Astragalus with the Os Naviculare.

This articulation appears calculated for considerable motion,
as well from the form of the two surfaces concerned in it, as
the perfect state of their articulating investments. Their mo-
tions are restrained to a certain degree, by ligaments, which are
situated on the upper and internal surfaces of the foot.

Fig. 10.* — On the upper surface of the foot, is a

thin broad ligament formed of parallel and
oblique fibres, stretched from the upper and
inner face of the astragalus to the upper
surface of the scaphoides or naviculare ;
some of the fibres extend even to the cunei-
forme bones.

— On the under surface of the foot, these
bones are connected by two ligaments, cal-
caneo-scaphoid internum, and externum.
— The internal arises from the inner margin
of the lesser apophysis of the os calcis, and
runs obliquely forwards and inwards, to be
inserted on the inner and under surface of
the os naviculare. It is a strong ligament,
and contributes much to the preservation of
the arched form of the foot. On its under
surface is a trochlea for the tendons of the flexor pollicis and

* The ligaments of the sole of the foot. 1. The os calcis. 2. The astragalus.
3. The tuberosity of the scaphoid bon£ . 4. The long calcaneo-cuboid ligament.
5. Part of the short calcaneo-cuboid ligament. 6. The internal calcaneo-sca-
phoid ligament. 7. The plantar tarsal ligaments. 8, 8. The tendon of the
peroneus longus muscle. 9, 9. Plantar tarso-metatarsal ligaments. 10.
Plantar ligament of the metatarso-phalangeal articulation of the great toe ; the
same ligament is seen upon the other toes. 11. Lateral ligaments of the meta-
tarso-phalangeal articulation. 12. Transverse ligament. 13. The lateral liga-
ments of the phalanges of the great toe ; the same ligaments are seen upon the
other toes.

ARTICULATION OF THE OS CALCIS AND CUBOIDES. 267

flexor longus digitorura. Below it is also in contact with the
tendon of the tibialis posticus, and above with the head of the
astragalus, which it in part supports. y

— The external is at the outer side of the last ; it arises from the
under surface of the greater apophysis of the os calcis, and is
inserted upon the under internal surface of the os naviculare. —

The ligaments which pass from the anterior internal extremity of the os calcis
to the os naviculare, and support the head of the astragalus, ought to be
observed with attention during the examination of this joint.

Articulation of the Os Calcis and Cuboides.

The articulating surfaces of this joint are arranged in the
usual manner.

There are two additional ligaments : one placed on the upper,
and the other on the under surfaces of the bones. The upper
ligament is thin ; but the under ligament is one of the strongest
of the foot ; and its fibres are blended with those which form
the sheath for the tendon of the peroneus longus, as it passes
along the groove in the cuboides.

— These ligaments are called the superior and inferior calca-
neo-cuboid. The latter is by some considered as consisting of
two ligaments, the short and long.

— The superior passes from the upper anterior surface of the
os calcis to the adjoining surface of the os cuboides.
— The inferior is the strongest ligament of the foot. It arises
from the inferior back part of the os calcis, and part of its
fibres are inserted upon the oblique ridge or the tendon of the
peroneus longus which traverses the under part of the os cu-
boides. This part is sometimes called the short inferior calca-
neo-cuboid ligament. The greater part of the fibres of this
ligament, pass beyond the ridge, and are inserted in fasciculi
upon the basis of the third and fourth metatarsal bones. These
subtend the groove, in which passes the tendon of the peroneus
longus muscle, and constitute the long inferior calcaneo-cuboid
ligament.

— The other bones of the foot are united in general by dorsal and
plantar ligaments like the corresponding bones of the hand. —

268 PARTICULAR LIGAMENTS,

CHAPTER VI.

OF PARTICULAR LIGAMENTS, AND OF THE SITUATION OF
THE INDIVIDUAL BURS^E MUCOS^E.

Enumeration of the most important Ligaments, which have not been described,

Ligaments proper to the Scapula.

THE triangular ligament (ligamentum coraco-acromialis)
arises broad from the external surface of the coracoid process,,
and becomes narrower where it is fixed to the posterior margin
of the acromion. It confines the tendon of the supra-spinatus
muscle, and assists in protecting the upper and inner part of the
joint of the humerus.

The posterior ligament of the scapula (coracoid) is some-
times double, and is stretched across the semilunar notch of
the scapula, forming that notch into one or two holes for the
passage of the superior posterior scapulary vessels and nerves.
It also gives rise to part of the omo-hyoideus muscle.

The Interosseous Ligament of the Forearm,

Extends between the sharp ridges of the radius and ulna,
filling up the greater part of the space between these two
bones, and is composed of small fasciculi, or fibrous slips, which
run obliquely downwards and inwards. Two or three of these,
however, go in the opposite direction, and one of them, termed
oblique ligament and chorda transversalis cubiti, is stretched
between the tubercle of the ulna and under part of the tubercle
of the radius. In different parts of the ligament there are
perforations for the passage of blood-vessels from the fore to
the back part of the bone, and a large opening is found at the
upper part of it which is filled up by muscles. It prevents the
radius from rolling too much outwards, and furnishes a com-
modius attachment for muscles.

LIGAMENTS OF THE HAND. 269

ligaments retaining the Tendons of the Muscles of the Hand
and Fingers in their proper positions.

The anterior annual ligament of the wrist is stretched across
from the projecting points of the pisiform and unciform bones,
to the os scaphoides and trapezium, and forms an arch which
covers and preserves in their places the tendons of the flexor
muscles of the fingers.

The vaginal ligaments of the flexor tendons are five mem-
branes, connecting the tendons of the sublimis, first to each
other, and then to those of the pro fund us ; forming, at the same
time, bursae mucosae which surround the tendons.

The vaginal or crucial ligaments of the phalanges arise from
the ridges on the concave side of the phalanges, and run over
the tendons of the flexor muscles of the fingers. Upon the
body of the phalanges, they are thick and strong, to bind down
the tendons, but over the joints they are thin, and have, in
some parts, a crucial appearance, to allow the ready motion of
the joints.

The accessory ligaments of the flexor tendons of the fingers
are small tendinous fraena, arising from the first and second
phalanges of the finger. They run obliquely forwards within
the vaginal ligaments, terminate in the tendons of the two flexor
muscles of the fingers, and assist in keeping them in their places.

The posterior annular ligament of the wrist is part of the
aponeurosis of the forearm, extending across the back of the
wrist, from the extremity of the ulna and os pisiforme to the
extremity of the radius. It is connected with the small annular
ligaments which tie down the tendons of the extensores ossis
metacarpi et primi internodii pollicis, and the extensor carpi
ulnaris.

The vaginal ligaments adhere to the last mentioned, and
serve as sheaths and bursae rnucosae to the extensor tendons of
the hand and fingers.

The transverse ligaments, of the extensor tendons, are
aponeurotic slips running between the tendons, near the heads
of the metacarpal bones, and retaining them in their places.
23*

^x

270 LIGjyiENTS OF THE STERNUM.

Ligaments on the Anterior part of the Thorax.

The membrane proper to the sternum is a firm expansion,
composed of tendinous fibres running in different directions,
and covering the anterior and posterior surfaces of the bone,
being confounded with the periosteum.

The ligaments of the cartilago ensiformis are part of the
proper membrane of the sternum, divided into strong bands,
which run obliquely from the under and forepart of the second
bone of the sternum, and from the cartilages of the seventh
pair of ribs, to be fixed to the cartilago ensiformis. The liga-
ments covering the sternum serve considerably to strengthen
that bone.

There are also thin tendinous expansions which run over
the intercostal muscles at the fore part of the thorax, and connect
the cartilages of the ribs to each other.

Ligaments of the Bones of the Pelvis.

Articulations of the vertebral column with the pelvis. The
lowermost lumbar vertebra is articulated with the sacrum in the
same manner as the vertebrae are articulated with each other,
viz., by the common anterior and posterior ligaments of the
spinal column, intervertebral substance, yellow elastic liga-
ments, capsular ligaments covering the oblique processes, and
the interspinal ligaments. Two other ligaments connecting it
with the bones of the pelvis, are denominated the ilio lumbar or
lumbo-iliac ligament, and the sacro-vertebral or lumbar sacral
ligament. From their direction they are sometimes called the
two transverse ligaments of the pelvis.

The ilio-lumbar, (see fig. 62, p. 257,) arises from the point of
the transverse process of the last lumbar vertebra, and from
the oblique process below and is inserted for about two inches
into the crest of the ileum just above its posterior superior
spinous process. It sometimes from being blended with adipose
substances presents the appearance of two distinct ligaments.

The sacro-vertebral, arises from the under part of the trans-
verse process of the last lumbar vertebra, and is inserted into

LIGAMENTS OF THE STERNUM. 271

the upper part of the base of the sacrum near the anterior liga-
ment of the sacro-iliac articulation with which some of its fibres
are blended. y

The proper ligaments of the pelvis, are as follows, viz. 1.
Those which connect the ilium and sacrum. 2. Those between
the sacrum and ischium. 3. Those between the sacrum and
coccyx, and 4. Those which join the two pubic bones together.

1. Ligaments connecting the Ilium and Sacrum.

A long flat ligament called the sacro-spinous (lig. sacro-
spinosum) arises from the posterior superior spinous process
of the os ilium descends obliquely and is inserted into the third
and fourth transverse processes of the sacrum. It sometimes
presents the appearance of two separate ligaments.

The ligaments which form the sacro-iliac junction are two
in number, and are called anterior and posterior.
— The anterior sacro-iliac ligament, consists of a thin plane
of short, strong ligamentous fibres, passing from bone to bone on
the anterior face of the joint.

The posterior sacro-iliac ligament, is the main stay of the
articulation. It consists of many strong bundles of ligamentous
fibres, which cross horizontally over the posterior part of the
joint, and are attached by one extremity to the rough surface of
the ilium immediately behind the joint, and by the other to
two eminences on the lateral margin of the sacrum, as well as
the rough surfaces of the bone between them.

2. Ligaments connecting the Sacrum and Ischium.

The two sacro-ischiatic ligaments, see fig. 71, are situated in
the under and back part of the pelvis. They arise nearly in
common from the transverse processes of the os sacrum, from
the under and lateral part of that bone, and from the upper part
of the os coccygis. The first, called the external posterior or
greater, descends obliquely, to be fixed to the tuberosity of
the os ischium. The other, called the lesser, internal or ante-
rior sacro-sciatic or sacro-ischiatic ligament, runs transversely
to be fixed to the spinous process of the os ischium. These

272

LIGAMENTS OF THE PELVIS,

two ligampnts assist in binding the bones of the pelvis, in sup-
porting its contents, and in giving origin to part of its muscles.
Fig. 71.* There are two membra-

nous productions which
are connected with the
large sacro-ischiatic liga-
ment, termed its superior
and inferior appendices.

The superior appendix,
which is tendinous, arises
from the back part of the
os ilium, and is fixed along
the outer edge of the liga-
ment, which it increases in
breadth.

The inferior or falci-
form appendix, situated
within the cavity of the
pelvis, the back part of which is connected with the middle
of the large external ligament, and the rest of it is extended
round the curvature of the os ischium.

These two productions assist the large sacro-ischiatic liga-
ment in furnishing a more commodious situation for, and
insertion of, part of the gluteus maximus, and obturator
internus muscles.

The large holes upon the back part of the os sacrum are
also surrounded with various ligamentous expansions, pro-
jecting from one tubercle to another, and giving origin to mus-
cular fibres, and protection to small vessels and nerves which
creep under them.

* Ligaments of the pelvis and hip-joint. The view is taken from the side.
1. The oblique sacro-iliac ligament. The other fasciculi of the posterior sacro-
iliac ligaments are not seen in this view of the pelvis. 2. The posterior sacro-
ischiatic ligament. 3. The anterior sacro-ischiatic ligament. 4. The great
sacro-ischiatic foramen. 5. The lesser sacro-ischiatic foramen. 6. The coty-
loid ligament of the acetabulum. 7. The ligamentum teres. 8. The cut edge
of the capsular ligament, showing its extent posteriorly as compared with its
anterior attachment. The obturator membrane only partly seen.

LIGAMENTS OF THE PELVIS. 273

3. Ligaments connecting the Sacrum and Os Coccygis.

A general covering is sent down from the ligaments of the
os sacrum, which spreads over and connects the different pieces
of the os coccygis together, allowing considerable motion, as
already mentioned, in the description of this bone. This
forms what is called the anterior and posterior coccygeal lig-
aments.

The posterior longitudinal ligaments of the os coccygis
descend from those upon the dorsum of the os sacrum, to be
fixed to the back part of the os coccygis. The ligaments of
this bone prevent it from being pulled too much forwards by
the action of the coccygeus muscle, and they restore the bone
to its natural situation, after the muscle has ceased to act.

4. Ligaments connecting the Ossa Pubis.

A ligamentous Jibro-cartilage, resembling in structure the
intervertebral substance, unites the two ossa pubis so firmly
together at their symphysis as to admit of no motion, excepting
in the state of pregnancy, when it is frequently found to be so
much softened as to yield a little in the time of delivery. ^

— There are a few transverse ligamentous fibres on the front
part of the symphysis pubis, called the anterior pubic ligament.
These interlace in front of the symphysis.
— There are also a few irregular fibres on the posterior face
of the articulation crossing from bone to bone, called the poste-
rior pubic ligament.

— The sub, or interpubic ligament occupies the summit of the
arch of the pubis. It is about half an inch in breadth, and
passes from the crus of the pubis of one side to that of the
other. —

— A thick strong band of fibres is found crossing from bone to
bone, on their superior face, and filling up the inequalities
which exist there ; it is called the superior pubic ligament.

The obturator membrane, or ligament of the foramen thy-
roideum, adheres to the margin of the foramen thyroideum, and
fills the whole of that opening, excepting the oblique notch at

274 LIGAMENTS OF THE FOOT.

its upper part for the passage of the obturator vessels and nerve.
It assists in supporting the contents of the pelvis, and in giving
origin to the obturator muscles. See fig. 62, p. 257.

The interosseous ligament of the kg fills the space between
the tibia and fibula like the interosseous ligament of the forearm,
and is of a similar structure ; being formed of the oblique fibres,
and perforated in various plaoes for the passage of vessels and
nerves.

At the upper part of it there is a large opening, where the
muscles of the opposite sides are in contact ; and where vessels
and nerves pass to the fore part of the leg.

It serves chiefly for the origin of part of the muscles which

belong to the foot.

»

Ligaments retaining the Tendons of the Muscles of the Foot
and Toes in their proper position.

The annular ligament of the tarsus is a thickened part of
the aponeurosis of the leg, splitting into superior and inferior
portions, which bind down the tendons of the extensors of the
toes upon the forepart of the ankle.

The vaginal ligament of the tendons of the peronei muscles,
behind the inkle is common to both, but divides at the outer
part of the foot, and becomes proper to each. They preserve
the tendons in their places, and are the bursae of these tendons.

The laciniated ligament arises from the inner ankle, and
spreads in a radiated manner, to be fixed partly in the cellular
substance and fat, and partly to the os calcis, at the inner side
of the heel. It encloses the tibialis posticus and flexor digitorum
longus.

The vaginal ligament of the tendon of the extensor proprius
pollicis runs in a crucial direction.

The vaginal ligament of the tendon of the flexor longus
pollicis surrounds this tendon in the hollow of the os calcis.

The vaginal and crucial ligaments of the tendons of the flexors
of the toes inclose these tendons on the surfaces of the pha-
langes, and form their bursae mucosae.

The accessory ligaments of the flexor tendons of the toes, as in

BURSJE MUCOS.E. 275

the fingers, arise from the phalanges, and are included in the
sheaths of the tendons in which they terminate.

The transverse ligaments of the extensor tendons run between
them, and preserve them in their places behind the roots of
their toes.

Enumeration of the most important Bursse Mucosae.
Those about the articulation of the Shoulder are situated,

1. Under the clavicle, where it plays upon the coracoid pro-
cess.

2. Between the triangular ligament of the scapula and the
capsular ligament of the humerus.

3. Between the point of the coracoid process and capsular
ligament of the humerus.

4. Between the tendon of the subscapiilaris muscle and cap-
sular ligament of the humerus, frequently communicating with
the cavity of that joint.

5. Between the origin of the coraco-brachialis and short
head of the biceps muscles, and capsular ligament of the hu-
merus.

6. Between the tendon of the teres major and the os humeri,
and upper part of the tendon of the latissimus dorsi.

7. Between the tendon of the latissimus dorsi and os
numeri.

8. Between the tendon of the long head of the biceps flexor
cubiti and the humerus.

The Bursae marked 3 and 5 are sometimes absent.
Near the articulation of the Elbow there are,

1. With a peloton of fat, between the tendon of the biceps
an^ tubercle of the radius.

2. Between the tendon common to the extensor carpi radialis
brevier, extensor digitorum communis, and round head of the
radius. •

3. A small bursa, between the tendon of the triceps extensor
cubiti and olecranon.

276 BURSJE MUCOSJE OF THE UPPER EXTREMITY.

On the Forearm and Hand are situated,

1. A very large bursa surrounding the tendon of the flexor
pollicis longus.

2. Four long bursae lining the sheaths which enclose the
tendons of the flexors upon the fingers.

3. Four short bursae on the forepart of the tendons of the
flexor digitorum sublimis in tlfe palm of the hand.

4. A large bursa between the tendons of the flexor pollicis
longus, the forepart of the radius, and capsular ligament of the
os trapezium.

5. A large bursa between the tendons of the flexor digitorum
profundus, and the forepart of the end of the radius, and capsu-
lar ligament of the wrist.

These two last mentioned bursse are sometimes found to communicate with

each other.

7. A bursa between the tendon of the flexor carpi radialis
and os trapezium.

8. Between the tendon of the flexor carpi ulnaris and os
pisiforme.

9. Between the tendon of the extensor ossis metacarpi pollicis
and radius.

10. A large bursa common to the extensores carpi radiales,
where they cross behind the extensor ossis metacarpi pollicis.

11. Another common to the entensores carpi radiales, where
they cross behind the extensor secundi internodii pollicis.

12. A third, at the insertion of the tendon of the extensor
carpi radialis brevior.

13. A bursa for the tendon of the extensor secundi internodii
pollicis, which communicates with the second bursa common to
the extensores carpi radiales.

14. Another bursa between the tendon of the extensor secun-
di internodii pollicis and metacarpal bone of the thumb. t

15. A bursa between the tendons of the extensor of the fore,
middle, and ring fingers, and ligament of the wrist.

16. For the tendons of the extensor of the little finger.

17. Between the tendon of the extensor carpi ulnaris and
ligament of the wrist.

BURSJE MUCOSJE OF THE THIGH AND ANKLE. 277

Upon the Pelvis and upper part of the Thigh there are,

1 . A very large bursa between the iliacus internus and psoas
rnagnus muscles, and the capsular ligament of the thigh bone.

2. One between the tendon of the pectinalis muscle and the
thigh bone.

3. Between the gluteus medius and trochanter major, and
before the insertion of the tendon of the pyriformis.

4. Between the tendon of the gluteus minimis and trochanter
major.

5. Between the gluteus maximus and vastus externus.

6. Between the gluteus medius and pyriformis.

7. Between the obturator internus and os ischium.

8. An oblong bursa continued a considerable way between the
obturator internus, gemini, and capsular ligament of the thigh
bone. %

9. A small bursa at the head of the semimembranosus and
biceps flexor cruris.

10. Between the origin of the semitendinosus and that of the
two former muscles.

11. A large bursa between the tendon of the gluteus maximus
and root of the trochanter major.

12. Two small bursae between the tendon of the gluteus
maximus and thigh bone.

About the Joint of the Knee are,

1. A large bursa behind the tendon of the extensors of the
leg, frequently found to communicate with the cavity of the
knee joint.

2. Behind the ligament which joins the patella to the tibia,
in the upper part of the cavity of which a fatty substance
projects.

3. Between the tendons of the sartorius, gracilis, semitendi-
nosus, and tibia.

4. Between the tendons of the semimembranosus and gemel-
lus, and ligament of the knee. This bursa contains a small one
within it, from which a passage leads into the cavity of the joint
of the knee.

24

278 BURSJE MUCOS.ZE OF THE ANKLE AND FOOT.

5. Between the tendon of the semimembranosus and the
internal lateral ligament of the knee, from which also there is a
passage leading into the joint of the knee.

6. Under the popliteus muscle, likewise communicating with
the cavity of the knee joint.

About the pinkie there are,

1. A bursa between the tendon of the tibialis anticus, and
under part of the tibia and ligament of the ankle.

2. Between the tendon of the extensor proprius pollicis pedis,
and the tibia and capsular ligament of the ankle.

3. Between the tendons of the extensor digitorum longus,
and ligament of the ankle.

4. Common to the tendons of the peronei muscles.

5. Proper to the tendon of the peroneus brevis.

6. Between the tendon achillis and os calcis, into the cavity
of which a peloton or mass of fat projects.

7. Between the os calcis and flexor pollicis longus.

8. Between the flexor digitorum longus and the tibia and os
calcis.

9. A bursa between the tendon of the tibialis posticus and
the tibia and astragalus.

On the Sole of the Foot are also,

1. A second bursa for the tendon of the peroneus longus,
with an oblong peloton of fat within it.

2. One common to the tendon of the flexor pollicis longus,
and that of the flexor digitorum profundus, at the upper end of
which a fatty substance projects.

3. Another for the tendon of the tibialis posticus.

4. Several for the tendons of the flexors of the toes.

PART III.
M Y O L O G Y.

CHAPTER VII.

GENERAL ANATOMY OF MUSCLES *

THAT soft, fibrous, red-colored substance, which constitutes
so large a proportion of the volume of the more perfect ani-
mals, is called Flesh or Muscle.

By the contraction of this substance, the spontaneous mo-
tions of animals are produced ; and, on this account the fibres
which compose it have long been regarded with particular
attention.

Muscular fibres are not only arranged in those- regular
masses on the trunk and limbs of the body, which are so fami-
liar to us by the name of muscles, but they also exist in some
of the most important viscera, and produce the internal, as well
as the external motions of animals.

— Muscles have been divided in man, and the superior ani-
mals, into two classes. The first class consists of those which
produce the external motions of the body, and are placed
exteriorly ; these contract under the influence of the will, are
the agents by which are executed the animal or voluntary func-
tions which place the animal in relation with the exterior
world, and are called the muscles of animal life, muscles of the
life of relation, voluntary muscles, etc. These form by far the
largest portion of the whole mass, and are attached in general,
by one or both extremities to the skeleton. They are solid,

* Muscles were first named according to their figure and situation, in 1587,
by Jacques Dubois, surnamed Sylvius, a member of the Faculty of Medicine, in
Paris. — H.

280 GENERAL ANATOMY OF MUSCLES.

that is, have no cavity in their interior, and vary much in their
size. The second class consists of those placed in the interior
of the body, and which effect the movements requisite in the
various processes of nutrition and generation. These are not
under the control of the will, and are called the muscles of
organic life, muscles of the life of nutrition, involuntary muscles,
etc. They are generally membraniform, and assist in forming
the hollow organs, as in the heart, digestive canal, uterus and
bladder. With the exception of those of the heart, the fibres
of this class of muscles are of a pale color, and some entirely
colorless. A few of the muscles of animal life, as those of the
ears and some of those of the face, are likewise faintly colored,
and are considered by Isenflam,* as existing even in the adult
in a state of rudimental development, as their color and func-
tions are found much more fully manifested in some quadru-
peds.!

— The muscles in the inferior grades of animals appear to exist
in a rudimental condition, and become more and more nume-
rous, and of a color more and more red generally, as we
advance upwards from the zero point of the animal scale. In
the development of the human foetus they seem to undergo
analogous changes.

— They present themselves during the three first months of
foetal life, as gelatinous or viscous masses, very slightly tinged
with yellow, and with thin tendons, according to Isenflam,

* Anatomische Untersuchungen, by H. F. Isenflam, Professor at the Uni-
versity of Dorpat.

f This physiological division of the muscles into two classes, after Bichat, is
eminently useful to the student, in enabling him to simplify and generalize his
studies of the muscular system ; one class is not, however, wholly separate
from the other. Between, is interposed another subdivision of muscles, called
the Respiratory of Sir C. Bell, which with the muscles of the pharynx and
oesophagus, might be considered as a third or mixed class of muscles, as they
execute certain motions involuntarily and unconsciously to the individual, and
yet are under the influence of the will to perform motions for other purposes or
to execute the same motions more rapidly or more slowly. Thus, for instance,
the muscles of respiration which carry on the process of breathing during sleep,
produce involuntary sneezing, coughing and crying; and when placed under
the influence of the will are made to elicit the voice, etc. — P.

GENERAL ANATOMY OF MUSCLES. 281

already apparent in the flexors and extensors of the fingers and

toes.

— At the end of the fourth or fifth month, the muscles present

a reddish aspect, and at the period of birth, though they may

be readily dissected from each other, they are very soft, and of

a color much less deep than those of the adult, —

Muscular fibres are connected to each other by cellular mem-
brane. This membrane surrounds each muscle; and its
various lamina, gradually diminishing in thickness, pass be-
tween the different bundles of fibres, and the different fibres of
which each muscle is composed.

The fibres of muscles, when examined with magnifying
glasses, appear to be composed of fibrillae still smaller ; and it
has been supposed that this division of them extended beyond
our powers of vision, even when assisted by microscopes : but
so many errors have occurred in microscopical observations of
very minute objects, and so much difference exists between the
reports of different observers, that the subject at this time does
not interest many persons ; and very little attention is paid, by
the anatomists and physiologists of the present day, to the
opinions of those observers who supposed they had ascertained
the structure of the ultimate fibrillae.

— The cellular or recticular membrane investing the whole
muscle, is called the muscular sheath. It is formed round
every muscle of the body, but varies much in different places
in regard to thickness and strength. Each of the many larger
fasciculi) or bundles of fibres, (lacerti,) of which every muscle
is obviously composed, is surrounded in like manner by pro-
cesses sent inwards from the sheath, and is a perfect, though
diminutive representative of the entire muscle.
— This secondary sheath surrounding the fasciculi, sends pro-
cesses likewise inwards, and invests and separates the indivi-
dual fibres so called, or rather the primitive fasciculi, of which
each larger fasciculus is formed. These fibres or primitive
fasciculi themselves are again susceptible of subdivision into
what are called the ultimate muscular filaments, between
which, it is probable, though not susceptible of demonstration,
24*

282 STRUCTURE OF MUSCULAR FIBRES.

the elementary particles of cellular tissue likewise pass. In-
the muscles of organic life, the cellular tissue is less abundant,
but more dense than in those of animal life. In some parts,
especially in the digestive canal it is so dense and resistant as
to represent a sort of ligamentous tissue, and give attachment
to muscular fibres.

— This delicate sheath surrounding the primary fasciculus, has
been designated by Mr. Bowman as the sarcolemma, or the
primitive cellular investment of the muscular fibres. — The term
myolemma has been applied to the same structure by Mr. Wil-
son and Dr. Quain.

— The entire muscle thus appears naturally susceptible of three
subdivisions. 1st. Into fasciculi, or bundles of fibres. These
are the minutest subdivisions which can be made with the
naked eye, without resort to boiling or other mechanical means.
These are themselves collected into bundles, by septa which
pass in from the general sheath of the muscles, but which are
easily unraveled by a little dissection ; so that what is at first
sight mistaken by the student for a fasciculus, is in reality a
bundle of fasciculi. The size of each of these fasciculi, varies
in the different mtiscles of the body, and occasionally in the
same muscle, according to the number of fibres of which it is
composed. 2nd. Into fibres so called or the primitive fasciculi.
These are rendered very apparent by boiling, as seen daily in
culinary preparations, by which the muscular fibre is swoln,
while the cellular envelop, at the same time softened and
reduced to a gelatinous pulp, is readily burst. These fibres
also vary in their thickness, some having a diameter three or
four times as great as that of others, depending upon the num-
ber of elementary filaments — usually amounting to several hun-
dred— of which it is composed. 3d. Into the elementary, or
ultimate muscular filaments. These are wholly microscopical,
are not uniform in their diameter in all muscles, (those of organic
life being much smaller,) and vary considerably in the numbers
taken to constitute the muscular fibres of different size.* Each

* Meckel. torn. i. p. 378.

STRUCTURE OF MUSCULAR FIBRES. 283

of the muscular fibres, and also, each of the ultimate filaments,
according to Prochaska and Rudolphi, extend the whole length
of the fleshy part of the muscles, differing entirely in this respect
from the ultimate structure of the bones.

— Anatomists do not agree in regard to the diameter assigned
the ultimate muscular filament, and from its microscopical
diminutiveness any measurement can be considered as little
more than an approximation. They have been examined by
Hook, Lewenhoeck, Dehayde, Muys, and more recently still by
Prochaska and others. According to Prochaska, they are
generally straight and parallel with each other, flattened or
prismatic, and of a diameter one-fifth of that of the red globules
of blood. Autenreith supposed them equal to one-third of the
diameter. Prevost and Dumas found them by their measure-
ment, ^th part of an inch in diameter, five or six times
smaller than the red globules of the blood, and nearly equal,
as Miiller also has asserted, to the diameter of the chyle
globules, or to the central nuclei of the red globules of blood,
which may be considered the most minute compound constitu-
ents of the economy.

— The more recent microscopical measurements of Henle, Lauth,
Ficinis, Bruns and others, agree in giving to the ultimate or
elementary muscular filament of animal life, a diameter of Tgooo^h
part of an inch. The diameter of the primitive fasciculus, com-
monly called muscular fibre, which is cylindrical in shape, is
considered upon an average about Jsth part of an inch in diame-
ter. Each one is marked by striae or streaks, which pass trans-
versely round them, in slightly curved or wavy parallel lines
from fl^gg to T2oootn °f an incn apart.

— The nature of these striae which belong solely to the mus-
cles of animal life, are not well understood, whether they be
delicate fibres wound round the primary fasciculi, mere wrinkles
in its myolemma or sheath, or what seems more likely, depres-
sions corresponding with the breaks between the globules or
granules, which, appended end to end, constitute a primitive
filament. According to the microscopical observations of Messrs.

284 STRUCTURE OF MUSCULAR FIBRES.

Bowman and Wilson each ultimate fibril of animal life is com-
posed of a succession of cells, united by their flat surfaces, each
cell filled with a transparent substance, the essential element of
the muscle, termed by Mr. Wilson myoline. The development
of muscular fibre is supposed to take place by the intuitive
formation of cell germs, out of an original plastic deposit, a sort
of soil for the germs or cytoblaets, called the blastema.
— The primitive fasciculus, or muscular fibre of organic life,
which is solely under the influence of the ganglionic nervous
system, is paler and softer than those of animal life ; is not so
regularly arranged in a longitudinal and parallel direction ;
and is less easily divided into its primitive filaments. Though
each fibre is round if singly examined, the bundles which they
form are flattened, composing muscular membranes, often two
or three layers deep, the bundles crossing each other at differ-
ent angles, and forming networks and gratings. The most
remarkable character of the organic muscular fibre, is the
existence in it here and there of swellings somewhat larger
than the diameter of the fibre, and produced by the nuclei of
the original nucleated cells from which the fibre was devel-
oped.*—

These fibrills have been represented as simple hollow tubes,
as a series of globular vesicles, as continuations of arteries, as
termination of nerves, as structures of rhomboidal bodies, and
finally, as cellular.f

It is supposed by one of the latest observers, who appears to
be entitled to great attention,;]: that the muscular fibres are not
thus minutely divided : that a single fibre, when separated from

* For a more fall and interesting account of these microscopical investiga-
tions, see Human Physiology, fourth edition, by R. Dunglison, M. D., Professor
of the Institutes of Medicine and Medical Jurisprudence in Jefferson Medical
College, &c. &c. Phila., 1845.— P.

f A statement of these descriptions, with reference to the publications in
which they are contained, may be seen in the Elementa Physiologies of Haller,
vol. iv.

$ Carlysle, in the Croonian Lecture, London Phylosophical Transactions,
1805, Part I.

STRUCTURE OF MUSCULAR FIBRES. 285

the adhering extraneous substances, and viewed in a powerful
microscope, is a solid cylinder, formed of a pulpy substance,
irregularly granulated, and covered by a portion of the regular
membrane.

— The opinions of Sir A. Carlysle, are not at the present time,
deemed of much weight in anatomy ; subsequent researches
having shown them to be full of empty and reckless speculation.
Among those who believed the muscular fibre to be hollow, were
Sink and Mascagni ; the latter considered it as formed of little
cylinders, the walls of which are composed of absorbent vessels
and filled with a glutinous substance. More recently, Raspail
(Chimie Organique) has adopted a view which appears a
modification of, and no better founded than that of Mascagni.
He considers each fibre formed of a bundle of cylinders, the
cylinders made up of elongated vesicles, attached end to end,
and having a spiral arrangement. —

The connexion of these fibres with the blood-vessels and
nerves, is an important circumstance in the structure of
muscles.

The arteries of muscles are very numerous ; and they ramify
minutely. They are accompanied by veins; and it appears, by
the successful labors of Ruysch, that when these arteries are
fully injected, they not only communicate with the veins, but
also pour out some of their contents in a dew-like effusion in the
muscle.*

— With the exception of some of the viscera, as the lungs and
kidneys, there are few organs that receive as much blood as the
muscles.

— The arteries that supply the muscles, enter them at all points.
The larger trunks more generally enter at the middle of the
muscle, and ramify towards each extremity, the branches being
placed between the larger fasciculi or lacerti, so that the flow
of blood, may be less impeded during muscular contraction ;
minute branches only passing into the structure of the fasciculi.

* See Ruysch's description of the 96th preparation in his Thesaurus Quartus ;
and of the 35th preparation in Thesaurus Decimus,

286 VASCULARITY OF MUSCLES.

The veins which attend the arteries, are said by Bichat to have
few valves. The free distribution of blood to the muscles,
appears to be necessary to preserve them in a condition, healthy
and capable of contraction. When the supply of blood is cut
off by a ligature, the muscle gradually becomes paralyzed, and
does not regain its power, till it is again supplied by the anasto-
mosing branches.

— The color of the muscle does not seem dependent wholly on
the blood, but in part at least on their own peculiar structure,
as seen in many animals, where the flesh is white and the blood
red ; and in the muscles of organic life in man, many of which
are colorless, though more vascular than those of animal life.
— The absorbent vessels exist no doubt in all the muscles, but
they are traced with difficulty. They have been found in the
muscles of the tongue, face and diaphragm.* —

The blood-vessels must terminate, not in the cavities of the
muscular fibres, but exterior to these fibres ; otherwise the
dew-like effusion, would not be apparent ; and it is probable,
that the red color, which is so general in muscles, depends
upon a portion of blood effused from these vessels, and not
contained in them ; for it has been observed by Bichat, that in
drowned or strangled animals, black disoxygenated blood
occupied all the vessels, while the florid color of the muscles
continued unchanged ; which could not have been the case
if the color of the muscles was owing to the blood in the
vessels.

That the color of the red muscles is owing to blood, is
rendered certain by the fact that this color may be completely
washed away while the fibrous structure of the muscle remains
unchanged. From this also it may be inferred that the blood
is exterior to the muscular fibre, and to the vessels likewise.

It is said by Sabatier, that the color will likewise be
completely removed, by injecting a. large quantity of water
through the arteries ; this does not invalidate the inferences
drawn from the other facts ; for the water effused from the

* Vide Breschet, Sur le Systeme Absorbante. Paris. 1836.

THE TENDONS. 287

extreme branches of the arteries must necessarily wash away
the blood which was previously effused from the same
branches.

The water with which muscles have been washed, appears as
if some blood had been mixed with it ; it contains albumen and
gelatine, with some fibrine, and a peculiar extractive substance,
as well as the red coloring matter.

The substance of the muscle, when thus separated from the
above mentioned matter by washing, appears to be of the same
nature with the fibrine of the blood : and after boiling some time
in the water, it seems, like that substance, to consist of brown
insoluble fibres which are brittle when dry.

When the great function of muscles is under consideration,
nerves appear of more importance than blood-vessels.

The nerves appropriated to muscles of voluntary motion are
more numerous than those appropriated to any other parts,
except the organs of sense. They subdivide into very fine
fibrillae ; and it is the opinion of one of the latest observers, that
these fibrillae become soft and transparent, and finally blended
with reticular membrane which surrounds the muscular fibres.

It ought to be noted that muscles are indued with great sensi-
bility,- and that the smallest puncture cannot be made in them
without exciting pain.

Of the Tendons.

Thus arranged, the fibres of muscles are most generally attach-
ed to tendons, which are inserted into the bones these muscles
are intended to move. They are also, in some cases, inserted
into tendinous membranes, and other parts necessary to be
moved ; but in all such instances these parts are perfectly pas-
sive ; and the motion in which they are concerned is altogether
produced by the contraction of the muscular fibres.

— The tendons appear to be formed of a continuation of the
cellular membrane which envelops the fibres of the muscles.
The ultimate construction of muscles was shown in page 283,
to consist of a multitude of filaments each one composed of a
linear series of the muscular molecules ; each of the molecules

288 THE TENDONS.

being contained in a series of cells of the cellular tissue, all of
which are continuous with each other. The muscular matter is
found in general only in the middle part of the cellular tissue ;
the latter part is continued on at each extremity of the muscle,
where it is compacted into a solid mass, presents a ligamentous
appearance, and constitutes the tendons, or cords by which the
muscles are attached to the» periosteum covering the bone.
Hence the tendons are continuous with, and must obey to a
certain extent the contraction of every muscular fibre.
— The tendons exist under a great variety of forms : most
generally round or cylindrical, sometimes flat, radiated, bifur-
cated, etc., but are always susceptible, by a little dissection, of
being unfolded into a membrane. They have little vascularity,
no sensation in a healthy state, no nerves having ever been
traced into them, and are of a strength surpassing that of almost
any other substance of equal size. They have a great affinity
for phosphate of lime, especially in old persons, in whom it is
not very unusual to find them ossified ; and very frequently at
all stages of life, we find developed in their substance sesa-
moid bones.

—The muscles are often from inanition or want of use much
wasted away, the red muscular matter disappearing from the
cells in which its particles are contained. The cells however
remaining, if the system regains its vigor, or the muscles are
brought into use, they are filled anew with the muscular sub-
stance or myoline, and the muscle is restored to its former size,
and its contraction takes place again with its usual force.
- — From this mode of formation, it is evident that there must be
an exact relation between the force of the muscle, and the
strength of its tendons, even when the muscle is most fully de-
veloped. The size and power of the muscle is much dependent
upon its use.

w— The muscles of the legs in dancers, of the arms in black-
smiths, of the shoulders and back in porters, all obtain an in-
crease of bulk from use, which still better fits them for the
duties they have to perform. This is strongly exemplified in
birds ; the breast bone and muscles attached to it being more

PHENOMENA Or MUSCULAR MOTION. 289

strongly developed than those of the legs, in birds which are
much upon the wing ; the reverse taking place in the ostrich,
cassowary and penguin, which employ the wings only as akls to
the feet. —

Notwithstanding the great attention that has been paid to this
important operation of muscular fibres, the immediate cause is
yet unknown.

Muscular motion takes place under the following different
circumstances : —

1st. When irritation or stimulus is applied directly to the
muscular fibre.

2d. When irritation is applied to a nerve connected with the
muscles.

3d. When it is induced by volition.

There are several causes of muscular action which cannot be
arranged under either of these heads, although it is probable they
are not essentially different ; such as the motions of coughing
and sneezing, of yawning, &c.

The immediate irritation of a muscle is effected by every
mechanical process, which punctures, divides, lacerates or
extends its fibres ; by acrid, and, perhaps, other chemical and
peculiar qualities of the substance applied to the muscles ; by
a sudden change of temperature; and by electricity and gal-
vanism.

No satisfactory explanation has yet been made of the man-
ner in which muscular contraction is excited, either by the above-
mentioned agents, by irritation applied to a nerve, or by voli-
tion.

When a muscular fibre begins to contract, there is often the
appearance of a slight tremor in it. It becomes hard and rigid :
its length diminishes, and its diameter increases. If a muscle
makes an effort to contract, when the parts to which its extre-
mities are attached are prevented from moving towards each
other, so that contraction cannot take place, the muscle will
become hard and rigid notwithstanding.

— This tremor of the fibres, is called fibrillary agitation, (agi-
tation fibrillaire) and is heard when a stethoscope is applied
25

290 PHENOMENA OF MUSCULAR MOTION.

over the belly of a muscle during its contraction, or when the
end of the finger is introduced into the auditory meatus. During
the contraction of a muscle there is no change in its color, nor any
increase in the amount of blood thrown into it by the arteries as
was once supposed.

Fig. 71.* — With the aid of the microscope it is easy
to distinguish the manner in which the
contraction of a muscle is effected. Fig.
70, exhibits a magnified view of the mus-
cular fibres in a state of relaxation. When
they contract they form suddenly a num-
ber of zigzag flexions, or angular undula-
tions, opposite each other, as seen in fig.
'c 72, page 291, according to the observation
of Edwards,! Prevost, and Dumas. By
repeated experiments, these gentlemen
have determined that the flexures of each
fibre take place at certain determined points, and nowhere else.
These points are precisely at the places where the nerve a, the
trunk of which runs parallel with the muscular fasciculi, sends
off its filaments to traverse the muscular fibres, at the spot where
the angles of the undulations are formed. These nervous fila-
ments after having continued their course for some time, are
reflected in the form of loops, and return towards the brain, so
as to constitute with that organ a continuous circle.
— During the contraction of the muscle its extremities ap-
proach, for though the absolute length of the fibre remains the
same, the distance between its extremities is diminished by the
undulations. The will transmitted through the nerves is the
usual stimulus, which excites the voluntary muscles to con-
traction. Galvanic electricity, or disease of nervous centres
will produce the same result ; that of the involuntary muscles,
usually results from the impression made upon the organs, as

* a, Nerve, b b, Fasciculi of muscular fibres which are straight and parallel.
e, Nervous filament which separates from the nerve a, and crosses at right
angles, and at regular distances, the muscular fasciculi.

f Elements de Zoologie, etc., par M. H. Edwards. Paris, 1838.

PHENOMENA OF MUSCULAR MOTION. 291

by food in the stomach, blood in the heart, urine in the blad-
der, &c. —

It has often been inquired whether the
whole bulk of a muscle is diminished or
increased by its contraction. It now seems
generally agreed that the bulk is not increas-
ed ; and, if there is any real diminution of
the fibre itself, it is very small indeed.

The irritability of the muscular fibre, or
its power of contracting upon the application
of stimulus, exists in a greater degree in
some muscular parts than others. It is sus-
pended by the application of narcotic sub-
stances ; and it remains, in many cases, a short time after the
vital functions have ceased.

In a majority of cases a general contraction seems to take
place in the last moments of life ; and after death the body is
stiff in consequence of it ; all the movable parts being fixed in
the precise situation in which they were when the vital motions
ceased. The limbs being generally in a bended position at that
time, if an attempt be made to extend them it will be very
evident that the contracted state of the muscles impedes this
extension. When this contraction is once overcome, the limbs
continue perfectly flexible, and the muscles are ever after
relaxed ; but the force of contraction is sometimes so great that
it will require a considerable exertion of strength to overcome
it. This condition of the muscles, after death, although very
common, is not universal : and some dead subjects are perfectly
relaxed and flexible from the first cessation of the vital func-
tions.

The force with which muscles contract exceeds greatly their
inanimate power of cohesion. Thus, a muscle deprived of life,
would be completely lacerated by a weight suspended from it,
which it could readily raise by its contraction during life. This
force of contraction is so great, that the tendo-achillis and the

* The same muscle at the moment of contraction, and a b cf indicates the
same, as in Fig. 71.

292 PHENOMENA OF MUSCULAR MOTION.

patella have been repeatedly broken by the mere power of the
muscles, inserted into them.

The rapidity with which the successive contractions of the
same parts take place is extreme ; and as a striking proof of it,
the motions of the tongue, in rapid speaking or reading, are
referred to by physiologists.

The extent or degree of mustular contraction, is in some cases,
very great. In proof of this it was stated by the second
Monro, that crude mercury, which passes so readily through the
intestines, could not be carried along any parts of them whose
position happened to be perpendicular, (as the colon on the right
side when we stand,) unless the circular fibres of the intestine
contract behind it to such a degree as to close completely the
cavity of that tube.

An interesting question may be proposed here, — Whether
the power of motion, as above described, is exclusively enjoyed
by muscular fibres; whether these fibres must be supposed to
exist in all those parts of the body which occasionally perform
contraction ?

It has often been inferred, that parts were muscular because
they were capable of contraction ; but the question above ought
to be decided affirmatively before such inferences can be pro-
perly made.

The sac of the taenia hydatigena appears to be a membrane
of a peculiar structure, very different from muscle ; yet it is as
capable of contracting as if it were perfectly muscular.*

The membrane of the urethra does not appear to be muscular
in its structure ; and yet it has been seen to protrude a bougie,
which had passed near to the neck of the bladder, in a way that
indicated regular successive contraction, throughout its whole
extent.

The question above stated, may, therefore, be considered as
not yet decided affirmatively.

Muscular fibres are situated very differently in different parts.
They compose almost the whole substance of the heart, which

* See the Croonian Lecture by Mr. Home ; London Philosophical Transac-
tions for 1795, Part I. page 204.

PHENOMENA OF MUSCULAR MOTION. 293

is therefore called a hollow muscle. They also form one of the
coats of the stomach and intestines, and of the urinary bladder.

In the muscles on the trunk and limbs, their arrangement is
very various, being rectilinear, penniform, radiated, &c.

There are a great many short fibres, with an oblique direction,
in some muscles of small volume, which have therefore great
power and little motion, as in the semimembranosus.

— Contraction, though the only power that muscles appear
to exercise, is found likewise existing to some extent, in other
tissues of the body, where some effort and resistance is required
in the performance of their functions, without the necessity
of that perfect antagonism of action which muscles usually
establish. There appears, in fact, to be a regular gradation in
the changes of the condition of the muscular fibre. The mus-
cles of animal life in man are the most fully developed, most
highly colored, and enjoy to the fullest extent, the powers of
contraction. Their only vital action is that of contraction,
which as has been before explained, (see page 291,) causes
their ends to approach each other, by moving one or the other
of the bones, to which the two ends of the muscles are attached.
One of the bones is usually more readily moved than the other,
and that is the action of the muscle as usually set down in
books. But the student will do well to impress upon his mind,
that this is not the only movement which the muscle can effect,
and that if the part which it usually moves, becomes from
some adventitious cause more solidly fixed than the other,
as from a weight attached to it, or the opposing action of other
muscles, the contraction of the muscle will produce a move-
ment of the part, at which its other extremity is inserted. In
this way the action of muscles is beautifully varied, and very
complicated and useful movements are produced in the body,
by what seems a very simple arrangement of the muscles.
Thus the action of the great pectoral and latissimus dorsi mus-
cles is usually to pull down the arms when they have been
elevated by other muscles. But if the arms are thrown
upwards, and the hands grasp some place above, as the limbs
25*

294 ANTAGONISM OF MUSCLES.

of a tree, they then raise the body upwards towards the arms,
and thus become the muscles used in climbing.
— In violent dyspnoea, arising from spasmodic croup, asthma, or
other causes, the arms are frequently drawn upwards so firmly
by the muscles at the top of the shoulders, that the pectoralis
major and latissimus dorsi cannot pull them down. When they
contract, therefore, their extremities are made to approach
by raising the ribs to which they are in part attached, and thus
they become muscles of forced inspiration.
— The muscles of animal life are arranged, so that each one has
its antagonist, or opposing muscle. Thus, there are flexors to
bend the limbs, and extensors to straighten them, supinators and
pronators, elevators and depressors. The muscles, which are
very numerous, and like the bones, are said to be variously
estimated, from 368 by Chaussier, to 400 or more by other
writers, and producing by their single action a great variety of
movements, are yet combined together in pairs or much larger
numbers, so as to extend beyond computation the variety of
movements they are capable of producing. Thus the two mus-
cles already named, one of which, when acting separately, draws
the arm usually downwards and forwards, the other downwards
and backwards, when combined together draw it down in the
diagonal or middle line.

— The antagonism of the muscles is dependent upon their alter-
nate contraction : the shortened or contracted muscle, is re-
stored to its former length chiefly by the contraction of its an-
tagonist, but partly also by the resiliency of the cellular tissue
in its composition. They are also capable of acting to a certain
extent in unison, and thus give firmness and steadiness to the
limbs or other parts, and hold them in a fixed direction, as
occurs habitually in walking or standing, or pointing with the
arm.

— The antagonizing muscles do not appear to be equally
balanced in regard to power; thus the most usual attitudes, in
sleep, palsy or tetanus, where the muscles are uninfluenced by
the will, is the extended position for the back, flexion to the
arm in general, pronation to the fore arm, flexion to the lower

MODE OF INSERTION. 295

extremities and adduction to the foot. This is not dependent
upon a difference in length, as was supposed by Borelli, but,
according to Beclard, chiefly upon a difference in size, ^nd the
relative advantages of insertion upon the bones.
— Muscles have their tendons attached to the bones, in a man-
ner to give them the least mechanical power, but to effect the
greatest rapidity of motion ; for, as has been observed by
Archdeacon Paley, it is of far greater importance to man, to be
able to carry his arm quickly to his head, than to raise several
hundred weight more than he is now able to do : the two
qualities could not well exist together. All that could be done
to increase the power, without impairing the symmetry of the
body, or diminishing the celerity of its movements, has been
accomplished in endowing the muscles, with an extraordinary
force of contraction, at least ten fold as great as the student
would at first suppose it. The muscles are nearly all levers of
the third order.

— The force with which a muscle contracts, depends upon its
volume and the energy of the will, as well as some other circum-
stances. But the effect produced by the contraction will
depend in a great measure upon the manner in which it is
inserted upon the bone on which it acts.

— Thus, all things being the
same, the effect of the contrac-
tion will be the greater, in propor-
tion as the muscle is less obliquely
* connected with the bone. Thus
if the muscle m, figure 73, the
t force of which we suppose equal

to 10, is fixed perpendicularly to

the bone Z, the extremity of which a, is movable upon the
fulcrum point r, it will have to overcome only the weight of
the bone, and will carry it from the position a 6, into the direc-
tion of the line a c. But if this muscle acted obliquely upon
the bone in the direction of the line n b, it would then tend to
carry it in the direction of the line b n, and consequently to
force it against the fixed articular surface r. This latter being

296 FORCE OF MUSCULAR CONTRACTION.

a fixed surface, the bone can only turn upon the point r, as
upon a pivot, and the contraction of the muscle 71, having the
same force as the muscle m, would only be able to carry the
bone in the direction a d, and would require a force equal to
40, or four times that of m, to raise it in the direction of the
line a c.

—In the animal economy the muscles are inserted most usually,
very oblic[uely, and consequently in a manner little favorable
to the intensity of the result of their contraction. There is
nevertheless a very happy contrivance, which tends to diminish
the obliquity of their insertions, without marring the usefulness
or symmetry of the limbs. It is the articular swellings at the
extremities of the bones, which contribute also to the stability of
the joints, the advantage of which is seen in fig. 74.
— The tendon i of the muscle m, Fig. 74, is inserted as is the case
in general immediately below the articula-
tion, upon the mobile bone o, in a direc-
tion more approaching the perpendicular,
thus making the head of the bone a sort 'm"""
of pulley over which it acts, by which the
effect of the contraction is considerably
increased.

— A more striking instance is met with in the deltoid muscle.
Baron Haller, has made an interesting calculation of the abso-
lute force required to be exerted by the deltoid muscle, in order
to raise a weight of 60 pounds at the elbow, reckoning the weight
of the arm at five pounds of this. Its insertion is at an angle of 10
degrees upon the humerus, and at about one-third of the distance
between the shoulder and elbow. The force requisite to raise a
weight is exactly in the proportion of the distance, which the
weight from the fulcrum bears to that of the power from the
fulcrum. Thus, from the disadvantage of insertion, the force
requisite to be exercised there is three times as great as it would
be if inserted at the elbow ; therefore the actual weight lifted,
as far as the muscle is concerned, is equal to 180 pounds.
— But this is not all. The insertion of the muscle at an angle
of 10 instead of 90 degrees, takes off the purchase in the

MUSCLES OF ORGANIC LIFE. 297

proportion, as mathematicians have calculated, which 173 bears
to 1000. The augmented weight, or what is the same thing,
the increase of power necessary to raise it, amounts, therefore,
to no less than 1058, instead of the original 60 pounds. There
is yet another source of loss of effect in its contraction, which
requires great additional power in the muscle to counteract it.
The tendon of the muscle is never directly continuous with the
muscular fibres, and the loss of power is exactly in proportion
to the obliquity of their junction. The manner of this loss is
evinced, when we attempt to draw a body to us, at one time
with a crooked, and at another, with a straight bar or stick.
From this cause there would be a further loss of power of 228
pounds, which would augment the muscular energy, required to
raise the 60 pounds, up to 1284, according to this physiologist.
— In the muscles of organic life, destined to act without the aid
of the will, the system of antagonism, is much less perfectly
developed. These muscles are hollow, and their fibres are
arranged generally into layers, which cross each other at right
angles, and contribute, to a certain extent, to produce this effect.
The alternate contractions, of the auricles and ventricles of the
heart, and of the uterus, though these organs have, properly
speaking, no antagonist muscles, belong to this class. In some
of the hollow organs, as the bladder, the contracted muscular
fibres are expanded or antagonized, only by the matters which
collect in their cavities.

— The muscles of organic life, with the exception of the heart,
are of a pale or greyish white color. Some of them are so
thin, and of so pale a color, that it is impossible to draw the
line of distinction between them and cellular or aponeurotic
tissue.

— There is a regular gradation between muscular and desmoid
cellular tissue, now called contractile fibre or contractile tissue,
and an occasional substitution of the one for the other, in parts
that require elastic resistance, or firm support, that has been
overlooked by many anatomists. The yellow elastic ligarnen-
tous tissue, appears to be one medium between the muscular
and ligamentous tissue. Comparative anatomy shows us that

298 CONTRACTILE TISSUE.

parts formed in one animal of the elastic yellow tissue, are in
others composed of muscular fibres. Thus, the suspensory
ligaments of the sheath of the penis, are ligamentous in the
horse, and muscular in the mule and bull. The middle coat of
the arteries, which is composed of the elastic yellow tissue in
man, is muscular in certain parts of the arterial system of the
elephant.

— The kindred nature of these two tissues, is likewise strongly
manifested by chemical analysis. The yellow elastic tissue
consists chemically of albumen, osmazome and fibrine.* The
thick yellow elastic ligament which supports the weight of the
abdominal viscera in the horse, and others of the solipediae,
consists, in man, only of the fascia superficialis abdominis, and
forms, as a late writer is disposed to think, the abdominal pouch,
(poche musculaire,) of the didelphic animals, such as the
opossum and kangaroo.

— The parietes of the urethra, which, in man, is strongly elastic,
in the horse and many other animals is endowed with a strong
coat of palish muscular fibres. On close examination it will
be found in man, that the reddish fibres of the contractile tissue
which constitute the dartos muscle, are also extended so as to
cover the corpus cavernosum penis and the urethra ; over this
latter organ it is not improbable that they sometimes become the
seat of stricture. They run more or less parallel, and near to
one another, over the scrotum, where they are interwoven with
transverse fibres and bundles of cellular substance — or they
form plexuses, as on the penis, which resemble the terminal
plexuses, of nerves, with this difference, that the individual
fibres interlace and amalgamate.

— This same reddish contractile fibre is found by the microscope to
be interwoven in various places with the tissue of the skin, and
that peculiar corrugation of the skin known under the name of
goose flesh, is supposed to be produced by their agency. They
act with such force upon the scrotum, as occasionally to make
it hard as a ball, shrink it greatly in size, and force the testicles

* Consid. sur les aponeuroses abdom. servant d'introduction a 1'histoire des
Hernies, dans les Monodactyles, par Girard, fils.

CHEMICAL COMPOSITION. 299

up towards the inguinal rings. This contractile tissue enters
as an element, into the constitution of the penis and clitoris,
and probably also into that of the blood vessels, and the'excre-
tory ducts of the glands. When viewed under the microscope,
the contractile fibre is found different from the round fibres of
the common fibrous tissue ; they are larger, redder, and possess
a peculiar kind of transparency. The muscular fibres on the
inner face of the prostrate glands, and the muscles of Wilson
on the membranous part of the urethrae seem to be allied to
this class of tissue. This opinion seems borne out by the de-
velopment of the muscles in the foetus, as previously quoted
from Isenflam.

— Muscles are composed chemically, according to Berzelius,
principally of fibrine ; but they contain also albumen, gelatine,
osmazome, phosphates of soda, ammonia and lime, carbonate
of lime, and some free lactic acid. If the analysis is pushed
farther— to the destruction of the flesh, there is developed a great
quantity of nitrogen, hydrogen, oxygen and carbon, some iron,
phosphorus, soda and lime.

300 INDIVIDUAL MUSCLES.

CHAPTER VIII.

OF THE INDIVIDUAL MUSCLES.

Muscles of the Teguments of the Cranium.

THE skin that covers the cranium is moved by a single broad
digastric muscle, and one small pair.

1 . Occipito-Frontalis,

.Arises fleshy from the transverse protuberant ridge near the
middle of the os occipitis laterally, where it joins with the tem-
poral bone ; and tendinous from the rest of that ridge back-
wards, opposite to the lateral sinus ; it rises after the same
manner on the other side. From thence it comes straight
forwards, by a broad thin tendon, which covers the upper part
of the cranium at each side, as low down as the attollens auris,
to which it is connected, as also to the zygoma, and covers a part
of the aponeurosis of the temporal muscle ; at the upper part of
the forehead it becomes fleshy, and descends with straight fibres.

Inserted into the orbicularis palpebrarum of each side, and
into the skin of the eyebrows, sending down a fleshy slip be-
tween them, as far as the compressor naris and levator labii
superioris alaeque nasi.

Use. Pulls the skin of the head backwards ; raises the eye-
brows upwards ; and, at the same time, it draws up and wrin-
kles the skin of the forehead.

2. Corrugator Supercilii,

Arises fleshy from the internal angular process of the os
frontis, above the joining of the os nasi and nasal process of
the superior maxillary bone ; from thence it runs outwards, and
a little upwards.

Inserted into the inner and inferior fleshy part of the occipito-
frontalis muscle, where it joins with the orbicularis palpebrarum,

MUSCLES OF THE EAR.

301

75.*

and extends outwards as far as the middle of the superciliary
ridge.

Use. To draw the eyebrow of that side towards trie other,
and make it project over the inner canthus of the eye. When
both act, they pull down the skin of the forehead, and make it
wrinkle particularly between the eyebrows.

Muscles of the Ear.
1. Attollens Auris,

Arises, thin, broad, and tendinous, from the tendon of the

occipito-frontalis, from
which it is almost in-
separable, where it co-
vers the aponeurosis of
the temporal muscle.

Inserted into the up-
per part of the ear, op-
posite to the antihelix.

Use. To draw the ear
upwards, and make the
parts, into which it is
inserted, tense.

2. Anterior Auris ,

Arises, thin and mem-
branous, near the pos-
terior part of the zygo-
ma.

Inserted into a small
eminence on the back of
the helix, opposite to the
*! yW •' "v concha.

Use. To draw this eminence a little forwards and upwards.

* g, Occipito-frontalis. m, Nasal slip of do.
Levator labii superioris alseque nasi. 5, Masseter.

n, Compressor naris. k,
q, Attollens auris. r, Re-

trahentes auris, usually two in number, p, Platysma myoides. 5, Sterno-
cleido-mastoid. u, Trapezius. v, Splenius capitis. i, Splenius colli. TV, Del-
toid. The rest of the muscles known by references to the cuts No. 76, 77, 78.

26

30*2 MUSCLES OF THE EYELIDS.

3. Retrahentes Auris,

Arise, sometimes by three, but always by two distinct small
muscles, from the external and posterior part of the root of the
mastoid process, immediately above the insertion of the sterno-
cleido-mastoid muscle.

Inserted into that part of the^back of the ear which is oppo-
site to the septum that divides the scapha and concha.

Use. To draw the ear back, and stretch the concha.

Muscles of the Eyelids.

The palpebrae or eyelids, have one muscle common to both,
and the upper eyelid one proper to itself.

1. Orbicularis Palpebrarum,

Arises, by a number of fleshy fibres, from the outer edge of
the orbitar process of the superior maxillary bone, and from a
tendon near the inner angle of the eye ; these run a little down-
wards, then outwards, over the upper part of the cheek, below
the orbit covering the under eyelid, and surround the external
angle, being loosely connected only to the skin and fat ; run
over the superciliary ridge of the os frontis, towards the inner
canthus, where they intermix with those of the occipito-fron-
talis and corrugator supercilii ; then covering the upper eyelid,
they descend to the inner angle opposke to the inferior origin
of this muscle, firmly adhering to the internal angular process
of the os frontis, and to the short round tendon which serves to
fix the palpebrae and muscular fibres arising from it.

Inserted, by the short round tendon, into the nasal prdcess
of the superior maxillary bone, covering the anterior and upper
part of the lachrymal sac ; which tendon can be easily felt at
the inner canthus of the eye.

Use. To shut the eye, by drawing 'both lids close together,
the fibres contracting from the outer angle towards the inner,
press the eyeball, squeeze the lachrymal gland, and convey the
tears towards the puncta lachrymalia.

— When the muscle is in strong action, its upper fibres

MUSCLES OF THE EYEBALL. 303

cause the skin of the forehead to descend, the lower ones elevate
the integuments of the cheek. Like the other sphincters, this
is a mixed muscle. The fibres which are supposed te» be the
proper voluntary portion, are those which correspond to the
margin of the orbit, and are of a red color. The involuntary
fibres, form the thin portion which covers the lids, (musculus
ciliaris of Albinus,) and are of a pale color, like the muscles
of organic life. They contract involuntarily while we are awake,
in the action of winking, and during sleep in maintaining the
lids closed. —

The ciliaris of some authors is only a part of this muscle
covering the cartilages of the eyelids, called cilia or tarsi.

There is often a small fleshy strip, which runs down from
the outer and inferior part of this muscle above the zygomati-
cus minor, and joints with the levator labii superioris alaeque
nasi.

2. Levator Palpebrce Superioris,

Arises from the upper part of the foramen opticum of the
sphenoid bone, through which the optic nerve passes, above the
levator oculi, near the trochlearis muscle.

Inserted, by a broad thin tendon, into the cartilage that sup-
ports the upper eyelid, named tarsus.

Use. To open the eye, by drawing the eyelid upwards ;
which it does completely, by being fixed to the tarsus, pulling
it below the eyebrow, and within the orbit.*'

Muscles of the Eyeball

The muscles which move the globe of the eye are six, viz :
four straight, and two oblique.

The four straight muscles very much resemble each other : all

Arising by a narrow beginning, a little tendinous and fleshy,

from the bottom of the orbit around the foramen opticum of

the sphenoid bone, where the optic nerve enters, so that they

* There is no antagonist muscles provided especially to depress the lower lid.
Its depression is effected, according to the suggestion of Sir C. Bell, by the pro-
trusion of the eyeball. — p.

MUSCLES OF THE EYE.

may be taken out adhering to this nerve ; and all having strong
fleshy bellies.

Inserted at the forepart of the globe of the eye into the ante-
rior part of the tunica sclerotica, and under the tunica adnata,
at opposite sides, which indicates both their names and Use ; so
that they scarcely require any farther description than to name
them singly. The union of thai tendinous insertions forms the
tunica albuginea.

1. Levator Oculi, (Rectus Superior,)
Arises from the upper part of the foramen opticum of the

sphenoid bone, below the levator palpebra? superioris, and runs

forwards to be

Inserted into the superior and forepart of the tunica sclerotica,

by a broad thin tendon.

Use. To raise up the globe of the' eye.

2. Depressor Oculi, (Rectus Inferior,)
Arises from the inferior part of the foramen opticum.
Inserted opposite to the former.

Use. To pull the globe of the eye down.

3. Adductor Oculi, (Rectus Internus,)

Fig. 76.* Arises, as the former, be-

tween the obliquus superior
and depressor, being from its
situation, the shortest.

Inserted opposite to the in-
ner angle.

Use. To turn the eye to-
wards the nose.

* The muscles of the eyeball ; the view is taken from the outer side of the
right orbit. 1, A small fragment of the sphenoid bone around the entrance of
the optic nerve into the orbit. 2. The optic nerve. 3. The globe of the eye.
4. The levator palpebrse muscle. 5. The superior oblique muscle. 6. Its car-
tilaginous pulley. 7. Its reflected tendon. 8. The inferior oblique muscle, the
small square knob at its commencement is a piece of its bony origin broken off.
9. The superior rectus. 10. The internal rectus almost concealed by the optic
nerve. 11. Part of the external rectus, showing its two heads of origin.
32. The extremity of the external rectus at its insertion ; the intermediate por-
tion of the muscle having been removed. 13. The inferior rectus. 14. The
tunica albuginea, formed by the expansion of the tendons of the four recti.

MUSCLES OF THE EYE. 305

4. Abductor Oculi, (Rectus Externus,)

Arises from the bony partition between the foramen opticum
and foramen lacerum, being the longest from its situation ;
and is

Inserted into the globe opposite to the outer canthus.

Use. To move the globe outwards.

The oblique muscles are two : «

Obliquus Superior, seu Trochlearis,

Arises, like the straight muscles, from the edge of the fora-
men opticum at the bottom of the orbit, between the levator
and abductor oculi ; from thence, runs straight along the pars
plana of the ethmoid bone to the upper part of the orbit, where
a cartilaginous trochlea is fixed to the inside of the internal
angular process of the os frontis, through which its tendon
passes, and runs a little downwards and outwards, enclosed in a
loose membranous sheath.

Inserted by a broad thin tendon, into the tunica sclerotica,
about half way between the insertion of the attollens oculi and
optic nerve.

Use. To roll the globe of the eye, and turn the pupil down-
wards and outwards, so that the upper side of the globe is
turned inwards, and the inferior part to the outside of the
orbit, and the whole globe drawn forwards towards the inner
canthus.

2. Obliquus Inferior,

Arises, by a narrow beginning, from the outer edge of the
orbitar process of the superior maxillary bone, near its juncture
with the os unguis ; and running obliquely outwards, is

Inserted into the sclerotica, in the space between the abductor
and optic nerve, by a broad and thin tendon.

Use. To draw the globe of the eye forwards, inwards, and

downwards ; and, contrary to the superior, to turn the pupil

upwards towards the inner extremity of the eyebrow ; at the

same time, that the external part of the globe is turned towards

26*

306 MUSCLES OF THE NOSE.

the inferior side, and the internal rolls towards the upper
part.

The Muscle of the Nose.

There is only one muscle on each side that can be called
proper to the nose, though it is affected by several muscles of
the face.

Compressor Naris, (Triangularis seu Transversalis .Mm*,)

Arises, by a narrow beginning, from the root of the ala nasi
externally, where part of the levator labii superioris alaeque
nasi is connected to it ; it spreads into a number of thin separate
fibres, which run up along the cartilage in an oblique manner
towards the dorsum of the nose, where it joins with its fellow,
and is

Inserted slightly into the anterior extremity of the os nasi and
nasal process of the superior maxillary bone, where it meets
with some of the fibres descending from the occipito-frontalis
muscle.*

Use. To compress the ala towards the septum nasi, particu-
larly when we want to smell acutely ; but, if the fibres of the
frontal muscle, which adhere to it, act, the upper part of this
thin muscle assists to pull the ala outwards. It also corrugates
the skin of the nose, and assists in expressing certain passions.
— It has been called by Columbus dilatans nasi, from a belief,
in which, Bourgery coincides, that when it acts with its extrem-
ity upon the nose as the fixed point, it dilates the nostril.
When the other extremity of the muscle is the fixed point, it
compresses it. —

Muscles of the Mouth and Lips.

The mouth has nine pair of muscles, which are inserted into
the lips, and a common one formed by the termination of these ;

* The nasal slip of fibres descending from the occipito-frontalis, is some-
times spoken of as a distinct muscle, under the name of Pyramidalis nasi.

MUSCLES OF THE MOUTH AND LIPS.

307

viz. three above, three below, three outwards, and the common
muscle surrounds the mouth.
The three above are,

1. Levator Anguli Oris,

Arises, thin and fleshy,
from the hollow of the
superior maxillary bone,
between the root of the
socket of the first dens
molaris and the foramen
infra orbitarium.

Inserted into the an-
gle of the mouth and
under lip, where it joins
with its antagonist.

Use. To draw the cor-
ner of the mouth up-
wards, and make that
part of the cheek oppo-
site to the chin promi-
nent, as in smiling.

Fig. 77 *

2. Levator Labii Superioris Alaque Nasi,

Arises by two distinct origins : the first broad and fleshy,
from the external part of the orbitar process of the superior
maxillary bone which forms the lower part of the orbit, imme-

* g, Occipito-frontalis. I, Levator labii superioris alaeque nasi. I, Levator
anguli oris. n, Compressor naris. o, Orbicularis palpebrarum ; the external
palpebral ligament, seen on the right side, extending to the ear. 3 3, Zygoma-
ticus major, and minor. 4, Orbicularis oris, with the slip to the lower part of
the septum of the nose, called by Albinus, nasalis labii superioris. 5, Masseter.
t, Depressor anguli oris. s s, Sternal and clavicular portions of the sterno-
cleido-mastoid. u, Trapezius seen at its upper part. 6, Sterno-hyoid. 7,
Sterno-thyroid. 8, Omo-hyoid. 9, Scalenus anticus. 10, Scalenus medius.

308 MUSCLES OF THE FACE.

diately above the foramen infra-orbitarium ; the second portion
arises from the nasal process of the superior maxillary bone,
where it joins the os frontis at the inner canthus, descending
along the edge of the groove for the lachrymal sac.

The first and shortest portion is

Inserted into the upper lip and orbicularis labiorum ; the
second and longest, into the upper lip and outer part of the ala
nasi.

Use. To raise the upper lip towards the orbit, and a little
outwards ; the second portion serves to draw the skin of the
nose upwards and outwards, by which the nostril is dilated.

3. Depressor Labii Superioris Alceque Nasi,

Arises, thin and fleshy, from the os maxillare superius, imme-
diately above the joining of the gums with the two denies inci-
sores and the dens caninus ; from thence it runs up under part
of the levator labii superioris alaeque nasi.

Inserted into the upper lip and root of the ala nasi.

Use. To draw the upper lip and ala nasi downwards and
backwards.

The three below are,

1. Depressor Anguli Oris,

Arises, broad and fleshy, from the lower edge of the maxilla
inferior, at the side of the chin, being firmly connected to that
part of the platysma myoides, which runs over the maxilla to
the angle of the mouth, to the depressor labii inferioris within,
and to the skin and fat without, gradually turning narrower ;
and is

Inserted into the angle of the mouth, joining with the zygo-
maticus major and levator anguli oris.

Use. To pull down the corner of the mouth.

2. Depressor Labii Inferioris,

Arises, broad and fleshy, interiflixed with fat, from the infe-

MUSCLES OF THE FACE,

309

rior part of the lower jaw next to the chin ; runs obliquely
upwards, and is

Inserted into the edge of the under lip, extends along OJEIC half
of the lid, and is lost in its red part.

Use. To pull the under lip and the skin of the side of the
chin downwards, and a little outwards.

Fig. 78.*

3. Levator Labii Inferioris,

Arises, from the lower jaw, at
the roots of the alveoli of two
denies incisores and of the cani-
nus ; is

Inserted into the under lip
and skin of the chin.

Use. To pull the parts, into
which it is inserted, upwards.

The three outward are,

1. Buccinator,

Arises, tendinous and fleshy,
from the lower jaw, as far back
as the last dens molaris and forepart of the root of the coronoid
process ; fleshy from the upper jaw, between the last dens mo-
laris and pterygoid process of the sphenoid bone ; from the
extremity of this process it arises tendinous, being continued
between both jaws to the constrictor pharyngis superior, with
which it joins ; from thence, proceeding with straight fibres,
and adhering close to the membrane that lines the mouth, it is

Inserted into the angle of the mouth within the orbicularis
oris.

Use. To draw the angle of the mouth backwards and out-
wards, and contract its cavity, by pressing the cheek inwards,
by which the food is thrust between the teeth. — The bucci-

* a, Depressor labii inferioris. b, Buccinator, c, Levator anguli oris. e,
Levator labii inferioris (levator menti ;) this will be best seen in dissection by
inverting the lip and dissecting off the mucous membrane. /, Depressor anguli
oris. 5, Masseter. g, Tendon of the superior or internal oblique muscle of
the eye, after it passes its trochlea. h, Inferior oblique.

310 MUSCLES OF THE FACE.

nator acts principally in front on the commissure of the lips,
which it draws backwards horizontally, increasing transversely
the aperture of the mouth, and throwing the cheek into the
vertical folds, so conspicuous in old age. It thus antagonizes
the orbicularis oris. If both these muscles act together, the
lips are extended and pressed against the teeth. When the
cavity of the mouth is distended with air or liquids, the fibres
of this muscle are protruded and curved. If the muscle now
acts, the fibres become straightened, and the fluid is expelled
from the mouth, suddenly or gradually, according to the resist-
ance made by the orbicularis.

— This muscle assists also in mastication and deglutition, by
pressing the food from between the cheek and gums into the
cavity of the mouth. —

2. Zygomaticus Major,

Arises, fleshy, from the os malae, near the zygomatic suture.

Inserted into the angle of the mouth, appearing to be lost in
the depressor anguli oris and orbicularis oris.

Use. To draw the corner of the mouth and under lip
towards the origin of the muscle, and make the cheek promi-
nent, as in laughing.

2. Zygomaticus Minor,

Arises from the upper prominent part of the os malae, above
the origin of the former muscle ; and, descending obliquely
downwards and forwards, is

Inserted into the upper lip, near the corner of the mouth,
along with the levator anguli oris.

Use. To draw the corner of the mouth obliquely outwards
and upwards towards the external canthus of the eye.

The common muscle is the

Orbicularis Oris.

This muscle is, in a great measure, formed by the muscles
that move the lips ; the fibres of the superior descending, those

MUSCLES OF THE LOWER JAW. 311

of the inferior ascending, and decussating each other about the
corner of the mouth, run along the lip to join those of the oppo-
site side, so that the fleshy fibres appear to surround the^mouth
like a sphincter.

Use. To shut the mouth, by contracting and drawing both
lips together, and to counteract all the muscles that assist in
forming it.

There is another small muscle described by Albinus, which he
calls Nasalis labii superioris ; but it seems to be only some
fibres of the former connected to the septum nasi.

— The orbicularis, possesses a very varied and extensive action,
and may act as a whole or in parts. Its simplest action is to
close the mouth by bringing the lips together. The upper or
lower labial fibres may act separately, as well as those at the
commissures of the lips, by which they are enabled in turn, to
antagonize the different muscles, which are attached around. By
a very strong contraction of the labial and commissural fibres,
the lips are thrown forwards in a circular projection, as in whist-
ling. By the contraction of the inner labial fibres, they are
drawn inwards upon the teeth. —

Muscles of the Lower Jaw.

The lower jaw has four pair of muscles for its elevation or
lateral motions, namely, two, which are seen on the side of the
face, and two concealed by the angle of the jaw.

1. Temporalis,

Arises, fleshy, from a semicircular ridge of the lower and
lateral part of the parietal bone, from all the pars squamosa of
the temporal bone, from the external angular process of the os
frontis, from the temporal process of the sphenoid bone, and
from an aponeurosis which covers it ; from these different origins
the fibres descend like radii towards the jugum, under which
they pass ; and are,

Inserted, by a strong tendon, into the upper part of the coro-
noid process of the lower jaw ; in the duplicature of which ten-

312 MUSCLES OF THE LOWER JAW.

don this process is enclosed as in a sheath, being continued
down all its forepart to near the last dens molaris.

Use. To pull the lower jaw upwards, and press it against
the upper, at the same time drawing it a little backwards.

N. B. This muscle is covered with a tendinous membrane,
called its aponeurosis, which arises from the bones that give
origin to the upper and semicircular part of the muscle ; and
descending over it, is inserted into all the jugum, and the
adjoining part of the os fronds.

The use of this membrane is to give room for the origin of a
greater number of fleshy fibres, to fortify the muscle in its
action, and to serve as a defence to it.

2. Masseter,

Arises, by strong, tendinous, and fleshy fibres, which run in
different directions, from the superior maxillary bone, where it
joins the os malae, and from the inferior and anterior, part of the
zygoma, its whole length, the external fibres slanting backwards,
and the internal forwards.

Inserted into the angle of the lower jaw, and from that
upwards to near the top of its coronoid process.

Use. To pull the lower to the upper jaw, and by means of
its oblique decussation, a little forwards and backwards.

3. Pterygoideus Internus,

Arises, tendinous and fleshy, from the inner and upper part of
the internal plate of the pterygoid process, filling all the space
between the two plates ; and from the pterygoid process of the
os palati between these plates.

Inserted into the angle of the lower jaw internally.

Use. To draw the jaw upwards, and obliquely towards the
opposite side.

4. Pterygoideus Externus,

Arises from the outer side of the external plate of the ptery-
goid process of the sphenoid bone, from part of the tuberosity of
the os maxillare adjoining to it, and from the root of the tempo-
ral process of the sphenoid bone.

MUSCLES OF THE NECK. 313

Fig. 79.* Inserted into the cavity in the

neck of the condyloid process of
the lower jaw ; some of Hs fibres
are inserted into the ligament
that connects the movable carti-
lage and that process to each
other.

Use. To pull the lower jaw
forwards, and to the opposite
side ; and to pull the ligament
from the joint, that it may not

be pinched during these motions : when both external ptery-
goid muscles act, the fore teeth of the under jaw are pushed
forwards beyond those of the upper jaw.

The Muscles which appear about the anterior part of the Neck.
On the side of the neck are two muscles, or layers.

1. Musculus Cutaneus, vulgo Platysma Myoides, (see fig. 75,) /

Arises, by a number of slender separate fleshy fibres, from
the cellular substance that covers the upper part of the deltoid
and pectoral muscles ; in their ascent they all unite to form a
thin muscle, which runs obliquely upwards along the side of the
neck, adhering to the skin.

Inserted into the lower jaw, between its angle and the origin
of the depressor anguli oris, to which it is firmly connected, and
but slightly to the skin that covers the inferior part of the mas-
seter muscle and parotid glands.

Use. To assist the depressor anguli oris, in drawing the skin
of the cheek downwards ; and when the mouth is shut, it draws
all that part of the skin, to which it is connected, below the
lower jaw, upwards. — Some of its fibres are inserted into
the angle of the mouth, and are connected with the muscles of

* The two pterygoid muscles. The zygomatic arch and the greater part of
the ramus of the lower jaw have been removed in order to bring these muscles
into view. 1. The sphenoid origin of the external pterygoid muscle. 2. Its
pterygoid origin. 3. The internal pterygoid muscle.

27

314

MUSCLES OF THE NECK.

that region. They draw the corner of the mouth downwards,
and constitute the musculus risorius of Santorini. —

2. Sterno-cleido-mastoideus,

Arises by two distinct origins :
the anterior tendinous and a
little fleshy, from the top of the
sternum near its junction with
the clavicle ; the posterior,
fleshy, from the upper and an-
terior part of the clavicle ; both
unite a little above the ante-
rior articulation of the clavicle,
to form one muscle, which runs
obliquely upwards and out-
wards, to be

Inserted, by a thick strong
tendon, into the mastoid pro-
cess, which it surrounds ; and, gradually turning thinner, is
inserted as far back as the lambdoid suture.

Use. To turn the head to one side, and bend it forwards.

Muscles situated between the Lower Jaw and Os Hyoides.

There are four layers before, and two muscles at the side.
The four layers are,

1. Digastricus, (see fig. 78,)

Arises, by a fleshy belly, intermixed with tendinous fibres,
from the fossa at the root of the mastoid process of the temporal
bone, and soon becomes tendinous ; runs downwards and for-
wards : the tendon passes generally through the stylo-hyoideus
muscle ; then it is fixed by a ligament to the os hyoides ; and,
having received from that bone an addition of tendinous and
muscular fibres, runs obliquely forwards, turns fleshy again,
and is

* b, Buccinator, d, Depressor labii inferioris. h, Corrugator Supercilii.
n, Compressor naris. 5, Sterno-cleido-mastoid. t, Temporal, u, Trapezius.
v, Splenius capitis. v, Splenius colli. x, Digastricus. y, Mylo-hyoid. z, Stylo
hyoid. &, Hyo-glossus.

••e^£L'& ^JA s4f*,+^

MUSCLES OF THE NECK. 315

Inserted, by its anterior belly, into a rough sinuosity at the
inferior and anterior edge of that part of the lower jaw called
the chin.

Use. To open the mouth by pulling the lower jaw down-
wards, and backwards ; and when the jaws are shut, to raise
the os hyoides, and, consequently, the pharynx, upwards, as in
deglutition.

2. Mylo'Hyoideus,(Seefig'lS,)

Arises, fleshy, from all the inside of the lower jaw, between,
the last dens molaris and the middle of the chin, where it joins
with its fellow.

Inserted into the lower edge of the basis of the os hyoides,
and joins with its fellow.

Use. To pull the os hyoides forwards, upwards, and to one
side.

3. Genio-Hyoideus,

Arises, tendinous, from a rough protuberance in the middle of
the lower jaw internally, or on the inside of the chin.
Inserted into the basis of the os hyoides.
Use. To draw- this bone forwards to the chin.

4. Genio-Hyo-Glossus.

Arises, tendinous, from a rough protuberance in the inside of
the middle of the lower jaw ; its fibres run like a fan, forwards,
upwards, and backwards ; and are

Inserted into the whole length of the tongue, and base of the
os hyoides, near its cornu.

Use. According to the direction of its fibres, to draw the tip
of the tongue backwards into the mouth, the middle down-
wards, and to render its dorsum concave ; to draw its root and
os hyoides forwards, and to thrust the tongue out of the mouth.

The two muscles at the side are,

1. Hyo-Glossus,

Arises, broad and fleshy, from the base, cornu, and appendix,
of the os hyoides ; the fibres run upwards and outwards ; to be

f

316 MUSCLES OF THE NECK.

Inserted into the side of the tongue, near the stylo-glossus.
Use. To pull the tongue inwards and downwards.

2. Lingualis,

Arises from the root of the tongue laterally ; runs forwards
between the hyo-glossus and genio-glossus, to be

Inserted into the tip of the "tongue, along with part of the
atylo-glossus.

Use. To contract the substance of the tongue, and bring ii
backwards, and to elevate the point of the tongue.

9' JT -

- ••! •

Muscles situated between the Os Hyoides and Trunk.

These may be divided into two layers.
The first layer consists of two muscles,

1 . Sterno-Hyoideus, ,

Arises, thin and fleshy, from the cartilaginous extremity of
the first rib, the upper and inner part of the sternum, and from
the clavicle where it joins with the sternum.

Inserted into the base of the os hyoides.

Use. To pull the os hyoides downwards.

i

v 2. Omo-Hyoideus,

Arises, broad, thin, and fleshy, from the superior costa of the
scapula, near the semilunar notch, and from the ligament that
runs across it ; thence ascending obliquely, it becomes tendinous
below the sterno-cleido-mastoid muscle ; and, growing fleshy
again, is

Inserted into the base of the os hyoides, between its comu
and the insertion of the sterno-hyoideus.

Use. To pull the os hyoides obliquely downwards.

The second layer consists of three muscles.

1 . Sterno- Thyroideus3

Arises, fleshy, from the whole edge of the uppermost bone
of the sternum internally, opposite to the cartilage of the
rib, from which it receives a small part of its origin.

MUSCLES BETWEEN THE JAW AND OS HYOIDES. 317

Inserted into the surface of the rough line at the external part
of the inferior edge of the thyroid cartilage.
Use. To draw the larynx downwards.

2. Thyro-Hyoideus,

Arises from the rough line opposite to the insertion of the
former muscle.

Inserted into part of the basis, and almost all the cornu of
the os hyoides.

Use. To pull the os hyoides downwards, or the thyroid car-
tilage upwards.

3. Crico-Thyroideus ,
Which will be described with the larynx : Chap. xiv.

Muscles situated between the Lower Jaw and Os Hyoides

laterally.

They are five in number. They proceed three from the styloid
process of the temporal bone, from which they have half of
their names ; and two from the pterygoid process of the sphe-
noid bone.

The three from the styloid process are,

1 . Stylo-Glossusj

Arises, tendinous and fleshy, from the styloid process, and
from a ligament that connects that process to the angle of the
lower jaw.

Inserted into the root of the tongue, runs along its side, and is
insensibly lost near its apex.

Use. To draw the tongue laterally and backwards.

2. Stylo- Hyoideusj

Arises, by a round tendon, from the middle and inferior part
of the styloid process.

Inserted into the os hyoides at the junction of the base and
cornu.

Use. To pull the os hyoides to one side, and a little upwards
27*

319 MUSCLES OF THE PALATE.

N. B. Its fleshy belly is generally perforated by the tendon
of the digastric muscle, on one or both sides. There is often
another accompanying it, called stylo -hyoideus alter ; and has
the same origin, insertion, and use.

3. Stylo-Pharyngeus,

Arises, fleshy, from the root 6*f the styloid process.

Inserted into the side of the pharynx and back part of the
thyroid cartilage.

Use. To dilate the pharynx and raise it and the thyroid
cartilage upwards.

The two from the pterygoid process are,

1. Circumflexus, or Tensor Palati,

Arises from the spinous process of the sphenoid bone, behind
the foramen ovale, which transmits the third branch of the fifth
pair of nerves, from the Eustachian tube, not far from its osse-
ous part ; it then runs down along the pterygoideus internus,
passes over the hook of the internal plate of the pterygoid
process by a round tendon, which soon spreads into a broad
membrane.

Inserted into the velum pendulum palati, and the semilunar
edge of the os palati, and extends as far -as the suture which
joins the two bones. Generally some of its posterior fibres join
with the constrictor pharyngis superior, and palato-pharyngeus.

Use. To stretch the velum, to draw it downwards, and to one
side towards the hook. It has little effect upon the tube, being
chiefly connected to its osseous part.

2. Levator Palati,

Arises, tendinous and fleshy, from the extremity of the pars
petrosa of the temporal bone, where it is perforated by the
Eustachian tube, and also from the membranous part of the
same tube.

Inserted into the whole length of the velum pendulum
palati, as far as the root of the uvula, and unites with its
fellow.

MUSCLES OF THE FAUCES. 319

Use. To draw the velum upwards and backwards, so as to
shut the passage from the fauces into the mouth and nose.

^
Muscles situated about the passage of the Fauces.

There are two on each side, and a single one in the middle.
The two on each side are,

1. Constrictor Isthmi Faucium,

Arises, by a slender beginning, from the side of the tongue,
near its root ; thence running upwards within the anterior arch,
before the amygdala, it is

Inserted into the middle of the velum pendulum palati, at the
root of the uvula anteriorly, being connecte'd with its fellow, and
with the beginning of the palato-pharyngeus.

Use. Draws the velum towards the root of the tongue, which
it raises at the same time, and with its fellow, contracts the
passage between the two arches, by which it shuts the opening
into the fauces.

2. Palato-Pharyngeus,

Arises, by a broad beginning, from the middle of the velum
palati, at the root of the uvula posteriorly, and from the ten-
dinous expansion of the circumflexus palati. The fibres are
collected within the posterior arch behind the amygdala, and
run backwards to the top and lateral part of the pharynx, where
the fibres are scattered, and mix with those of the stylo-pha-
ryngeus.

Inserted into the edge of the upper and back part of the thy-
roid cartilage ; some of the fibres being lost between the mem-
brane of the pharynx, and the two inferior constrictors.

Use. Draws the uvula and velum downwards and backwards :
and, at the same time, pulls the thyroid cartilage and pharynx
upwards, and shortens it ; with the constrictor superior and
tongue, it assists in shutting the passage into the nostrils ; and.
in swallowing, it thrusts the food from the fauces into the
pharynx.

320 MUSCLES OF THE FAUCES.

Salpingo-Pharyngenus, (from salnd^ trumpet,')

Of Albinus, is composed of a few fibres of this muscle, which
Arise from the anterior and lower part of the cartilaginous
extremity of the Eustachian tube ; and are,

Inserted into the inner part of the last-mentioned muscles.
Use. To assist the former, and to dilate the mouth of the tube.
The one in the middle is the

Azygos Uvula,

Arises, fleshy, from the extremity of the suture which joins
the palate bones, runs down the whole length of the velum and
uvula, resembling a small earth-worm, and adhering to the ten-
dons of the circumflexi. Two are frequently met with.

Inserted into the apex of the uvula.

Use. Raises the uvula upwards and forwards, and shortens it.

Muscles situated on the posterior part of the Pharynx.
Of these there are three pair :

1. Constrictor Paryngis Inferior,

Arises, from the side of the thyroid cartilage, near the attach-
ment of the thyroideus and thyro-hyoideus muscles ; and from
the cricoid cartilage, near the crieo-thyroideus. This muscle is
the largest of the three ; and is

Inserted into the white line, where it joins with its fellow :
the superior fibres running obliquely upwards, covering nearly
one half of the middle constrictor, and terminating in a point ;
the inferior fibres run more transversely and covers the beginning
of the oesophagus.

Use. To compress that part of the pharynx which it covers,
and to raise it with the larynx a little upwards.

2. Constrictor Pharyngis Medius,

Arises from the appendix of the os hyoides, from the cornu
of that bone, and from the ligament which connects it to the
thyroid cartilage ; the fibres of the superior part running

MUSCLES OF THE GLOTTIS. 321

obliquely upwards, and, covering a considerable part of the
superior constrictor, terminate in a point.

Inserted into the middle of the cuneiforme process oFthe os
occipitis, before the foramen magnum, and joined to its fellow
at a white line in the middle back part of the pharynx. The
fibres at the middle part run more transversely than those above
or below.

Use. To compress that part of the pharynx which it covers,
and to draw it and the os hyoides upwards.

3. Constrictor Pharyngis Superior,

Arises, above, from the cuneiforme process of the os occi-
pitis, before the foramen magnum, near the holes where the
ninth pair of the nerves passes out ; lower down, from the
pterygoid process of the sphenoid bone ; from the upper and
under jaw, near the roots of the last dentes molares ; and
between the jaws, it is continued with the buccinator muscle ;
and with some fibres from the root of the tongue, and from the
palate.

Inserted into a white line in the middle of the pharynx,
where it joins with its fellow, and is covered by the constrictor
medius.

Use. To compress the upper part of the pharynx, and draw
it forwards and upwards. See article, pharynx.

Muscles situated about the Glottis.

They consist generally of four pair of small muscles, and a
single one. See Larynx, chapt. xiv.

Muscles situated on the Anterior Part of the Neck, close to the
Vertebra. (Pravertebral Muscles.)

These consist of one layer, formed by four muscles.

1. Longus Colli,

Arises, tendinous and fleshy from the bodies of the three
vertebrae of the back laterally ; and from the transverse process
of the third, fourth, fifth, and sixth vertebrae of the neck, near
their roots.

322

MUSCLES OF THE SIDE OF THE NECK.

Inserted into the forepart of the bodies of all the vertebrae of
the neck, by as many small tendons, which are covered with
flesh.

Use. To bend the neck gradually forwards, and to one side.

2. Rectus Capitis Internus Major,

Arises from the anterior points of the transverse process of
the third, fourth, fifth, and sixth vertebrae of the neck, by four
distinct beginnings.

Inserted into the cuneiforme process of the os occipitis, a little
before the condyloid process.

Use. To bend the head forwards.

3. Rectus Capitis Internus Minor,

Arises, fleshy, from the forepart of the body of the first ver-
tebra of the neck opposite to the Fig. 81.*
superior oblique process.

Inserted near the root of the
condyloid process of the os occi-
pitis, under, and a little farther out-
wards, than the former muscle.

Use. To bend the head forwards.

4. Rectus Capitis Lateralis,

Arises, fleshy, from the anterior
part of the point of the transverse
process of the first vertebra of the
neck.

Inserted into the os occipitis,
opposite to the foramen stylo-mas-
toideum of the temporal bone.

Use. To bend the head a little
to one side.

* The prse vertebral group of muscles of the neck. 1. The rectus anticus
major muscle. 2. The scalenus anticus. 3. The lower part of the longuscolli
of the right side ; it is concealed superiorly by the rectus anticus major. 4.
The rectus anticus minor. 5. The upper portion of the longus colli muscle.
6. Its lower portion ; the figure rests upon the seventh cervical vertebra. 7. The
scalenus posticus. 8. The rectus lateralis of the left side. 9. One of the
intertr an oversales muscles.

MUSCLES OF THE THORAX. 323

Muscles situated on the Anterior Part of the Thorax.

These may be divided into two layers. The first laye/ con-
sists of one muscle, named

Pectoralis Major,

Arises from the cartilaginous extremities of the fifth and
sixth ribs, where it always intermixes with the external
oblique muscle of the abdomen ; from almost the whole length
of the sternum : and from near half of the anterior part of the
clavicle ; the fibres run towards the axilla in a folding manner.

Inserted, by two broad tendons, which cross each other at
the upper and inner part of the os humeri, above the insertion
of the deltoid muscle, and outer side of the groove for lodging
the tendon of the long head of the biceps.

Use. To move the arm forwards, and obliquely upwards,
towards the sternum.

The second layer consists of three muscles. .

/^ J^^ •/?

1 . Subdavius,

Arises, tendinous, from the cartilage that joins the first rib to
the sternum.

Inserted, after becoming fleshy, into the inferior part of the

clavicle, which it occupies from within an inch of the sternum,

as far outwards as to its connexion, by ligament, with the
coracoid process of the scapula.

Use. To pull the clavicle downwards and forwards.

2. Pectoralis Minor,

Arises, tendinous and fleshy, from the upper edge of the
third, fourth, and fifth ribs, near where they join with their
cartilages.

Inserted, tendinous, into the coracoid process of the scapula :
but soon grows fleshy and broad.

Use. To bring the scapula forwards and downwards, or to
raise the ribs upwards.

324 MUSCLES OF THE THORAX.

3. Serratus Magnus,

Arises from the nine superior ribs, by an equal number of
fleshy digitations, resembling the teeth of a saw.

Inserted, fleshy, into the whole base of the scapula internally,
between the insertion of the rhomboid and the origin of the
subscapularis muscle, being folded about the two angles of the
scapula.

Use. To move the scapula forwards : and, when the scapula
is forcibly raised, to draw upwards the ribs. ^

Muscles situated between the Ribs, and within the Thorax.

Between the ribs, on each side, there are eleven double rows
of muscles, which are, therefore, named intercostals. These
decussate each other like the strokes of the letter X.

1. Intercostaks Eocterni,

Arise from the inferior acute edge of each superior rib, and
run obliquely forwards, the whole length from the spine to
near the joining of the ribs with their cartilages ; from which,
to the sternum, there is only a thin membrane covering the
internal intercostals.

Inserted into the upper obtuse edge of each inferior rib, as
ar back as the spine, into which the posterior portion is fixed.

2. Intcrcostales Interni,

Arise in the same manner as the external : but they begin at
the sternum, and run obliquely backwards, as far as the angle
of the rib ; and from that to the spine they are wanting.

Inserted in the same manner, as the external.

Use. By means of these muscles, the ribs are equally raised
upwards, during inspiration. Their fibres being oblique, give
them a greater power of bringing the ribs near each other, than
could be performed by straight ones. By the obliquity of
the fibres, they are almost brought contiguous : and as the fixed
points of the ribs are before and behind, if the external had
been continued forwards to the sternum, and the internal

ABDOMINAL MUSCLES, 325

backwards to the spine, it would have hindered their motion,
which is greatest in the middle, though the obliquity of the
ribs renders it less perceptible ; and, instead of raising th# fibres
fixed to the sternum and spine, would have depressed the ribs,

N. B. The portions of the external intercostals, which arise
from the transverse processes of the vertebrae where the ribs
are fixed to them, and other portions that pass over one rib
and terminate in the next below it, Albinus calls Levatores
costarum longiores et breviores*

The portions of the internal that pass over one rib, and are
inserted into the next below it, are, by Douglas, called
Costarum depressores proprii Cowperi.

These portions of both rows assist in raising the ribs in the
same manner as the rest of the intercostals.

The muscles within the thorax form one pair, viz.

Triangularis, or Stemo-Costalis,

Arises, fleshy, and a little tendinous, from all the length of
the cartilago-ensiformis laterally, and from the edge of the
lower half of the middle bone of the sternum, from whence its
fibres ascend obliquely upwards and outwards,

Inserted, generally by three triangular terminations, into the
lower edge of the cartilages of the third, fourth, and fifth ribs ;
near where these join with the ribs.

Use. To depress these cartilages, and the extremities of the
ribs ; and consequently to assist in contracting the cavity of the
thorax.

This muscle often varies ; and is sometimes inserted into the
cartilage of the second rib, sometimes into the cartilages of the
sixth rib.

Muscles situated on the anterior part of the Abdomen.

They consist of three broad layers on each side of the belly
and, of one layer in front.
The three layers are :

28

326

ABDOMINAL MUSCLES.

1. Obliquus Descendens Externus,

Arises, by eight heads, from the lower edges of an equal num-
ber of the inferior ribs, at a little distance from their cartilages :
it always intermixes in a serrated manner, with portions of the

Fig. 82.*

* The muscles of the anterior aspect of the trunk; on the left side the
superficial layer is seen, and on the right the deeper layer. 1. The pecloralis
major muscle. 2. The deltoid ; the interval between these muscles lodges the
cephalic vein. 3. The anterior border of the latissimus dorsi. 4. The serra-
tions of the serratus magnus. 5. The subclavius muscle of the right side. 6.
The pectoralis minor. 7. The coraco-brachialis muscle. 8. The upper part of
the biceps muscle, showing its two heads. 9. The coracoid process of the
scapula. 10. The serratus magnus of the right side. 11. The external inter-
costal muscle of the fifth intercostal space. 12. The external oblique muscle.
13. Its aponeurosis ; the median line to the right of this number is the linea
alba ; the flexuous line to its left is the linea semilunaris ; and the transverse
lines above and below the number, the lineae transversae, of which there were

ABDOMINAL MUSCLES. 327

serratus major anticus ; and generally coheres to the pectoralis
major, intercostals, and latissimus dorsi ; which last covers the
edge of a portion of it extended from the last rib to tKe spine
of the ilium. — It interdigitates by its five upper heads with
the serratus major anticus, and by the three lower with the
latissimus dorsi, where the latter arises from the ribs ; a slip
from the pectoralis covers the first or upper head. —

From these origins the fibres run obliquely downwards and
forwards, and terminate in the anterior half of the spine of the
ilium, and in a tendinous membrane, whose fibres are continued
in the same direction until they meet the fibres of the cor-
responding tendon of the other side, in a line which extends
from the ensiform cartilage to the symphysis pubis.

This line is called linea alba, from its white appearance,
which is owing to the connexion of three tendons with each
other, without the intervention of muscles, namely, those of the
external and internal oblique, and the transversalis.*

On each side of the line, two long narrow muscles, (the
recti.) are situated between these tendons, and do away the
white appearance ; but exterior to these muscles, the tendons

only three in this subject. 14. Poupart's ligament. 15. The external abdomi-
nal ring ; the margin abovs the ring is the superior or internal pillar ; the mar-
gin below the ring, the inferior or external pillar; the curved intercolumnar
fibres are seen proceeding upwards from Poupart's ligament to strengthen the
ring. The numbers 14 and 15 are situated upon the fascia lata of the thigh ;
the opening immediately to the right of fifteen is the opening for the saphena
vein. 16. The rectus muscle of the right side brought into view by the removal
of the anterior segment of its sheath : * the posterior segment of its sheath
with the divided edge of the anterior segment. 17. The pyramidalis muscle.
18. The internal oblique muscle. 19. The conjoined tendon of the internal
oblique and transversalis descending behind Poupart's ligament to the pectineal
line. 20. The arch formed between the lower curved border of the internal
oblique muscle and Poupart's ligament ; it is beneath this arch that the sper-
matic cord and hernia pass.

* According to Meckel, the linea alba performs the same office in the abdo-
men as the sternum does in the thorax, with this only difference, that it is not
formed of bone. The anterior tendons of the broad muscles are attached to it,
in the same way that the cartilages of the ribs are articulated with the sternum,
and the difference of tissue which exists between it and the sternum is attribu-
table to the general difference of structure between the abdominal and pectoral
cavities, the latter being formed almost entirely of osseous parts, whilst the
walls of the former are fleshy and tendinous. — r.

328 ABDOMINAL MUSCLES.

are again united, and form a white line on. each side, which is
called linea semilunaris, from its curved shape.

At the lower part of the tendon, near the os pabis, the fibred
are so arranged, that they form two bands more firm and
dense than the rest of the tendon, which are called columns :
these columns are separated from each other ; and the vacuity
between them is the abdominal ring, or aperture, for the
passage of the spermatic chord in males and the round ligament
of the uterus in females. This vacuity or aperture has an oval
form, which is occasioned by some additional tendinous fibres
at the upper part of it, that have a transverse direction*

The uppermost of the two columns is continued obliquely
downwards, and is inserted into the os pubis of the opposite
side, near the symphysis, decussating the fibres of the cor-
responding column of that side.

The lower edge of the tendon of the external oblique is
attached to the superior anterior spinous process of the ilium,
and is there blended \yith the tendinous fascia, which extends
down the thigh.

From this process the edge of the tendon is extended, like
the chord of a bow, across the concavity formed by the os
ilium and os pubis, and is inserted into the pubis near its sym-
physis. As it proceeds from the spine of the ilium towards the
pubis, the edge is folded inwards, so that the membrane is
doubled. The portion which is turned inwards, (Gimbernat's
ligament,) is very small at its commencement, and continues
so for a great part of its extent ; but becomes much broader
within an inch of its termination. This broad extremity is
inserted into the small process of the pubis near the sym-
physis, and into a ridge which continues backward from the
process to the brim of the pelvis, so that the tendinous mem-
brane at this part is doubled ; the part which is turned back
being about an inch broad at the place of its insertion into the
pubis.

This doubling forms a partial sheath near the pubis for con-
taining the spermatic chord, and supports it for a short distance
on the inside of the abdominal ring.

ABDOMINAL MUSCLES. 329

The edge formed by the fold of the membrane is called
Poupart's ligament, and is very firm and strong ; owing to
the membrane being thicker at that place. The real ^dge, or
termination of the portion which is folded inwards, is arranged
in the following manner : the part which is nearest to the spine
of the ilium is continued into the cellular membrane, or the
fascia, which is between the internal oblique and transversalis
muscles, and the iliacus internus.

But the edge of that part of Poupart's ligament which is
inserted into the ridge of the pubis seems to form a portion of
an oval opening, which is occupied in part, but not completely,
by the crural vessels.

— The femoral artery is found at the outer margin of this oval
opening, see fig. 82. The femoral vein is placed on the inner
side of the artery ; on the inner side of the vein again is left a
roundish opening, the proper crural ring, occupied only by some
loose fat, lymphatic vessels and a small gland, through which
the viscera protrude in crural hernia. —

— This edge of Poupart's ligament, inserted into the ridge or
crest of the pubis is of a triangular shape, and is called Gim-
bernai's ligament. It is one of the seats of stricture in crural
hernia. The base of the triangle is towards the syrnphysis
pubis. —

A portion of the fascia lata of the thigh, which covers these
vessels, passes under this portion of the tendon, and is also
inserted into the ridge of the pubis ; so that when the intestines
protrude at this aperture, and are strangulated, this portion of
the fascia of the thigh must also compress them. — This
portion of the fascia lata femoris, is called the crescentic or
falciform portion of the fascia lata. The sharp edge at its
inner part, by which it is nearly continuous with Gimbernat's
ligament, and which is directed downwards and backwards, is
called Key's ligament or the femoral ligament; it is directly
above or in front of the crural ring — that space between the
crural vein and Gimbernat's ligament, included in the sheath
of the femoral vessels, and through which the viscera protrude
in crural hernia. —

28*

330 ABDOMINAL MUSCLES.

The fascia lata of the thigh is connected with the external
or lower edge of Poupart's ligament, in its whole extent : this
is called the sartorial portion.

— The fascia lata may here be considered as divided into two
layers : 1st, The sartorial. 2d, The pectineal which contin-
uous above and without, as seen in fig. 83, is reflected behind

Fig*83*

llie sheath of the vessels, and over the anterior surface of the
pectineus muscle up to the spine of the pubis. The sheath of
the femoral vessels is formed by an extension downwards of
the fascia transversalis and fascia iliaca for about an inch and
a half between these layers of the fascia lata.-— And there is

* A section of the structures which pass beneath the femoral arch. 1. Pou-
part's ligament. 2, 2. The upper or sartorial portion of the fascia lata, attached
along the margin of the crest of the ilium, and along Ponpart's ligament, as far
as the spine of the os pubis (3). 4. The pubic or pectineal portion of the fascia
lata, continuous at 3 with the iliac portion, and passing outwards behind the
sheath of the femoral vessels to its outer border at 5, where it divides into two
layers ; one is continuous with the sheath of the psoas (6) and iliacus (7) ; the
other (8) is lost upon the capsule of the hip-joint (9). 10. The femoral nerve,
enclosed in the sheath of the psoas and iliacus. 11. Gimbernat's ligament.
12. The femoral ring, within the femoral sheath. 13. The femoral vein. 14.
The femoral artery : the two vessels and the ring are surrounded by the femo-
ral sheath, and thin septa are sent between the anterior and posterior wall of
the sheath, dividing the artery from the vein, and the vein from the femoral
ting.

ABDOMINAL MUSCLES. 331

also a fascia (fascia superficialis abdominis) which covers the
whole tendon of the external oblique muscle, and passes from it
down upon the fascia of the thigh : which also connects the
tendon of the external oblique to the fascia of the thigh, and
serves to bind it down. From these connexions it is probable
that the tendon is in a very different situation before dissection,
from what it is afterwards ; as the division of these connexions,
necessarily made by the dissection, renders it much more loose
than it could have been while the parts were undivided. This
structure has latterly been called the crural arch. The fascia
which covers the tendon of the external oblique muscle, and
descends upon the thigh, can be examined very easily in anasar-
cous subjects ; as in them, the cellular membrane, which is
situated between this fascia and the tendon, is somewhat dis-
tended by the effused fluid.

To prepare Poupart's ligament or the crural arch, for exami-
nation, remove carefully the cellular membrane from the tendon
of the external oblique, and also from the fascia of the thigh,
taking care not to remove any part of the fascia which passes
under the tendon to be inserted into the os pubis. Then make
an incision in the tendon of the external oblique, about three
inches above Poupart's ligament, parallel to it, and nearly of
the same length ; make a second incision from the upper end
of this, to the junction of the aforesaid ligament with the supe-
rior anterior spine of the ilium ; and a third incision from the
lower end to the abdominal ring. Dissect this flap carefully
from the internal oblique, until the spermatic chord, the cre-
master muscle, and the lower origin of the internal oblique,
are perfectly uncovered. After examining the internal surface
of the tendon and its insertion at the pubis, the fascia of the
thigh may be dissected, so that its connexion with the folded
edge of the tendon, and its insertion into the pubis, may also be
examined.

The external oblique muscles compress the abdomen, and
therefore contribute to the evacuation of its contents : if the
diaphragm is in a passive state, they force it upwards, by
pressing the abdominal viscera against it ; and thus assist in

332 ABDOMINAL MUSCLES.

producing expiration and its various modifications of coughing,
sneezing, &c.

They bend the spine forwards, or approach the thorax to the
pelvis.

When one acts separately, it bends the trunk obliquely to

the side on which it is situated.

•
3. Obliquus Ascendens Inter nus,

Arises from the spine of the ilium the whole length between
the posterior and superior anterior spinous process ; from the
os sacrum and the three undermost lumbar vertebrae, by a
tendon, (fascia lumborum) common to it, to the serratus
posticus inferior muscle, and to the latissimus dorsi ; from
Poupart's ligament, at the middle of which it sends off the
beginning of the cremaster muscle ; the spermatic chord in the
male, or round ligament of the womb in the female, passes
under its thin edge, with the exception of a few detached
fibres.

Inserted into the cartilago-ensiformis, into the cartilages of
the seventh, and those of the false ribs ; but, at the upper part,
it is extremely thin, resembling a cellular membrane, and only
becomes fleshy at the cartilage of the tenth rib. Here its
tendon divides into two layers ; the anterior layer, with a great
portion of the inferior part of the posterior layer, joins the
tendon of the external oblique, and runs over the rectus to be
inserted into the whole length of the linea alba. The posterior
layer joins the tendon of the transversalis muscle as low as
half way between the umbilicus and os pubis ; but, below this
place, only a few fibres of the posterior layer are seen, and the
rest of it passes before the rectus muscle, and is inserted into
the linea alba ; so that the whole tendon of the external
oblique muscle, with the anterior layer of the internal oblique,
passes before the rectus muscle ; and the whole posterior
layer of the internal oblique, together with the whole tendon
of the transversalis muscle, excepting at the inferior part,
passes behind the rectus, and is inserted into the linea alba.
At its undermost part, it is inserted into the forepart of the os
pubis.

ABDOMINAL MUSCLES. 333

Use. To assist the former ; but it bends the trunk in the
reverse direction.

Fig. 84.*

3. Transversalis,

Arises, tendinous, but soon becoming fleshy, from the inner
or back part of the cartilages of the seven lower ribs, where
some of its fibres are continued with those of the diaphragm
and the intercostal muscles ; by a broad thin tendon, connected
to the transverse processes of the last vertebra of the back, and
the four superior vertebrae of the loins ; fleshy, from the whole
spine of the os ilium internally, and from the tendon of the
external oblique muscle where it intermixes with some fibres
of the internal oblique.

Inserted into the cartilago-ensiformis, and into the whole
length of the linea alba, excepting its lowermost part.

Use. To support and compress the abdominal viscera, and

* Transverse section of abdomen. — a, Division of the tendon of the internal
oblique into two layers, forming a sheath in which is contained the rectus muscle
b, External oblique, r, Internal oblique, d. Transversalis. et Between the
last rib and the crista of the ilia, the fibres of the transversalis, arise from a
tendinous layer, which is trifoliate in its origin, according to Todd. /, The
anterior division, arising from the roots of the transverse processes, and cover-
ing the quadratus lumborum muscle, h, g, The middle, which is weak, attached
to the apices of the transverse processes. The posterior is the fascia lum
borum.

334

ABDOMINAL MUSCLES.

Fig. 85.* it is so particularly well adapted

for the latter purpose, that it
might be called the proper con-
strictor of the abdomen.

The long muscle in the middle

is named

•

Rectus AbdominiSj

Arises, by two heads, from the
ligament of the cartilage which
joins the two ossa pubis to each
other; runs upwards the whole
length of, and parallel to the linea
alba, growing broader and thin-
ner as it ascends.

Inserted into the cartilages of
the three inferior true ribs, and
often intermixed with some fibres
of the pectoral muscle.

It is generally divided by three
tendinous intersections : the first is at the umbilicus ; the
second, where it runs over the cartilage of the seventh rib ;
and the third in the middle between these ; and there is
commonly a half intersection below the umbilicus. These
intersections (linea transversce) seldom penetrate through
the whole thickness of the muscle : they adhere firmly to the

* A lateral view of the trunk of 'the body, showing its muscles, and particu-
larly the transversalis abdominis. ] . The costal origin of the lattissimus dorsi
muscle. 2. The serratus magnus. 3. The upper part of the external oblique
muscle divided in the direction best calculated to show the muscles beneath
without interfering with its indigitations with the serratus magnus. 4. Two of
the external intercostal muscles. 5. Two of the internal intercostals. 6. The
transversalis muscle. 7. Its posterior aponeurosis. 8. Its anterior aponeurosis
forming the most posterior layer of the sheath of the rectus. 9. The lower part
of the left rectus with the aponeurosis of the transversalis passing in front.
10. The right rectus muscle. 11. The arched opening left between the. lower
border of the transversalis muscle and Poupart's ligament, through which the
spermatic cord and hernia pass. 12. The gluteus maximus, and medius, and
tensor vaginae femoris muscles invested by fascia lata.

ABDOMINAL MUSCLES. 335

anterior part of the sheath, but very slightly to the posterior
layer.*

Use. To compress the forepart, but more particularly the
lower part of the belly ; to bend the trunk forwards, or to raise
the pelvis. By its tendinous intersection, it is enabled to con-
tract at any of the intermediate spaces ; and, by its connexion
with the tendons of the other muscles, it is prevented from
changing place, and from rising into a prominent form when
in action.

The short muscle in the middle is named

Pyramidatis,

Arises along with the rectus ; and running upwards within
the same sheath, is

Inserted, by an acute termination, near half way between
the os pubis and umbilicus, into the linea alba and inner edge
of the rectus muscle.

As it is frequently wanting in both sides without any incon-
venience, its

Use seems to be, to assist the inferior part of the rectus.

Muscles about the male Organs of Generation.

The testicles are said to have a thin muscle common to both,
and one proper to each.

The common muscle is called the

Dartos.

This consists of muscular fibres blended with the cellular
membrane lining the scrotum ; and therefore this portion of

* To obtain an accurate idea of the arrangement of the tendons of the three
large pair of abdominal muscles, it will be necessary to raise or separate the
external oblique muscle and tendon from the internal oblique and its tendon, as
far as the linea semilunaris, and to separate the internal oblique in the same
manner from the transversalis ; and then to make an incision in the tendon of
the external oblique parallel to the linea alba, and about an inch and a half
from it, so as to bring the whole of the rectus muscle into view. The structure
of the sheath which contains the rectus can then be examined.

336 PERINEAL MUSCLES.

skin is capable of being corrugated and relaxed in a greater
degree than the skin in other places.

The muscle proper to each testicle is the

Cremaster.

Arises from the internal oblique, where a few fibres of that
muscle intermix with the tran^versalis, near the juncture of the
os ilium and pubis, over which part it passes, after having
pierced the ring of the externus obliquus ; and then it descends
upon the spermatic chord.

Inserted into the tunica vaginalis of the testicle, upon which
it spreads, and is insensibly lost.*

Use. To suspend and draw up the testicle, and to compress
it in the act of coition.

The penis has three pairs of muscles :

1. Erector Penis.

Arises, tendinous and fleshy, from the tuberosity of the os
ischium, and runs upwards, embracing the whole crus of the
penis

Inserted into the strong tendinous membrane that covers the
corpus cavernosum penis, nearly as far as the union of these
bodies.

Use. To compress the crura penis, by which the blood is
pushed from it into the forepart of the corpora cavernosa ; and

* M. J. Cloquet says, that the scattered fasciculi of this muscle are collected
after their distribution on the tuniea vaginalis, and run up on the inner side of
the chord, to be inserted into the spine of the pubis. He makes the inference
from this, that the cremaster is a kind of muscular loop, drawn down by the
descent of the testicle. I am satisfied that the muscle in robust subjects, fre-
quently exists, more or less, after the manner in which he speaks of it : but, in
the emaciated, it is very indistinct, as regards such an insertion. In the cases
where I have seen this insertion into the spine of the pubis, the quantity of
muscular fibre has been by no means so great there as at its origin. This ob-
servation of M. Cloquet's is ingenious and interesting, but it is well worthy of
consideration, that Mr. John Hunter's opinion, in his paper on the descent of
the testicle, is opposed to it, and on the following grounds : in the young ram,
and in several other animals, the cremaster muscle is formed before the testicle
descends from the abdomen into the scrotum, being reflected along the guber-
naculum testis upwards towards the loins. Mr. Hunter could not, it is true,
verify the same observation on the human subject, but he is disposed, from
analogy, to believe that something of the kind exists. — H.

PERINEAL MUSCLES,

337

the penis is by that means more Fig. 86.*

completely distended. The erec-
tores seem, likewise, to keep the
penis in its proper direction.

2. Accelerator Urince seu Ejac-
ulator Seminis.

Arises, fleshy, from the sphinc-
ter ani and membranous part of
the urethra ; and tendinous, from
the crus, nearly as far forwards
as the beginning of the corpus
cavernosum penis : the inferior
fibres run more transversely ; and
the superior descend in an ob-
lique direction.

Inserted into a line in the middle of the bulb where it joins
with its fellow, by which the bulb is completely enclosed.

Use. To drive the urine or semen forwards ; and, by grasping
the bulb of the urethra, to push the blood towards the corpus
cavernosum and the glans, by which these parts are distended.

3. Transversus Perinei,

Arises from the tough fatty membrane that covers the tube-
rosity of the os ischium ; from thence it runs transversely
inwards, and is

* Cremaster, from Sir A, Cooper's work. 0, Rectus muscle, b, Descending
portion of the fascia superticialis. c, The internal oblique, d. Conjoined ten-
dons, e, The descending fibres of oblique. /, Point of insertion into the pubis.
g, Ascending fibres, h, One of the reversed arches.

The formation of the cremaster, appears to be completed by the testicle in
its descent, as Scarpa, Cloquet, Cooper, Velpeau, and Todd admit. Prior to
the descent, the gubernaculnm testis occupies the inguinal canal, and is covered
by the fibres of the cremaster which divide inferiorly into three processes ac-
cording to Mr. Curling. — The outer process which is the largest running to be
inserted on Poupart's ligament, the middle one to the bottom of the scrotum,
where it joins the dartos, the internal one to the os pubis and the sheath of the
rectus muscle. The testis is drawn down by the successive action of these
muscular bands of the gubernaculum, the testis as stated by Mr. Curling is
drawn first into the inguinal canal, then through the external abdominal ring.
and finally down into the bottom of the scrotal pouch, the fibres of the cremas-
ter remaining subsequently as a muscular envelop surrounding the g'and and
the front of the cord.

29

338 MUSCLES OF THE ANUS.

Inserted into the accelerator urinae, and into that part of the
sphincter ani which covers the bulb. The place of junction of
these muscles is called the perineal point or centre.

Use. To dilate the bulb, and draw the perineum and verge of
the anus a little outwards and backwards.

There is often a fourth muscle, named

•

Transversus Perinei Alter,

Arises behind the former, runs more obliquely forwards, and is
Inserted into that part of the accelerator urinae which covers
the anterior part of the bulb of the urethra.
Use. To assist the former.

In the Medico-Chirurgical Transactions, James Wilson, Esq. F. R. S. gives
the following account of two small muscles of the membranous part of the
urethra, viz: Each muscle has a tendon which, at first, is round, but soon be-
comes flattened as it descends. It is affixed to the back part of the symphysis
pubis, about one-eighth of an inch above the lower edge of the cartilaginous
arch of the pubes, and nearly at the same distance, below the attachment of the
tendon of the bladder : to which, and to the tendon of the corresponding muscle,
it is connected by very loose cellular membrane. The tendon descends at first
in contact with, and parallel to, its fellow : it soon becomes broader, and sends
off fleshy fibres, which also increase in breadth, and, when near the upper sur-
face of the membranous part of the urethra, separate from those of the opposite
side, spread themselves on the side of the membranous part of the urethra
through its whole extent ; then fold themselves under it, and meet in a middle
tendinous line with similar fibres of the opposite side.

Its action seems to be to draw up the membranous part of the urethra, and
compress it against the inside of the cartilaginous arch of the pubes ; and also
to contract the circle round the membranous portion, so as to diminish and even
close up the passage of the urine.* It is known under the name of the muscle
of Wilson .f

* I have frequently dissected for this muscle, and in only two or three cases have been
able to satisfy myself of its having an existence distinct from that of the Levator Ani. My
friend, Mr. Shaw, who occupies a distinguished rank among the cultivators of anatomy in
London, admits of this muscle, but says there is much difficulty in distinguishing it from the
ligament of the urethra, meaning, I presume, its triangular ligament.— H.

f The vertical muscular fibres discovered by Mr. Wilson and a transverse band connected
•with it, described by Mr. Guthrie, and both together commonly considered now as forming
the proper compressor urethra muscle.— From repeated examination, I have no doubt of
their being properly entitled to this name. — The muscle of Guthrie arises by a tendinous
point from the ranus of the Ischium and passing transversely inwards, splits into two layers
which by junction with its fellow of the opposite side, embrace the upper and lower surface
of the membranous portion of the urethrae from the bulb to which it is connected as front
to the point of the mastale to which it is attached behind.— p.

MCSCLES OF THE ANUS. 339

Muscles of the Anus.

The anus has a single muscle, and one pair.
The single muscle is

Sphincter Ani.

Arises from the skin and fat that surrounds the verge of the
anus on both sides, nearly as far as the tuber of the os ischium ;
the fibres are gradually collected into an oval form, and surround
the extremity of the rectum.

Fig. 81*

Inserted, before, by a narrow point, into the perineum, accel-
eratores urinae, and transversi perinei ; behind, by an acute ter-
mination, into the extremity of the os coccygis.

Use. Shuts the passage through the anus into the rectum ;
pulls down the bulb of the urethra, by which it assists in ejecting
the urine and semen. — The sphincter ani is always in a con-
tracted state, except at the time of the evacuation of the faeces.
When the sphincter is in a healthy state, it may by made by an effort
of the will to contract more strongly, but it cannot be made to relax.

* The muscles of the perineum. 1. The acceleratores urinae muscles ; the
figure rests upon the corpus spongiosum penis. 2. The corpus cavernosum of
one side. 3. The erector penis of one side. 4. The transversus perinei of one
side. 5. The triangular space through which the deep perineal fascia is seen.
6. The sphincter ani ; its anterior extremity is cut off. 7. The levator ani of
the left side ; the deep space between the tuberosity of the ischium (8) and the
anus, is the ischio-rectal fossa ; the same fossa is seen upon the opposite side.
9. The spine of the ischium. 10. The left coccygeus muscle. The boundaries
of the perineum are well seen in this engraving.

340 MUSCLES OF THE ANUS.

— The irritation induced by the accumulation of faeces in the
rectum, causes it at first to contract more strongly, and the
contraction continues till it is overcome, by the increasing
effort of the muscular fibres of the rectum, and the action of
the diaphragm and abdominal muscles. It acts also as an anta-
gonist to the levator ani muscles. —

-V. B. The sphincter interhus of Albinus and Douglas, is
only that part of the cellular fibres of the muscular coat of the
rectum which surrounds its extremity.

Levator Ani:

Arises from the os pubis within the pelvis, as far up as the
upper edge of the foramen thyroideum, and joining of the
os pubis with the os ischium ; from the thin tendinous mem-
brane that covers the obturator internus and coccygeus muscle,
and from the spinous process of the os ischium : its fibres run
down like rays from a circumference to a centre.

Inserted into the sphincter ani, acceleratores urinse, and anterior
part of the two last bones of the os coccygis ; surrounds the
extremity of the rectum, neck of the bladder, prostate gland, and
part of the vesicula seminalis ; so that its fibres behind and
below the os coccygis joining it with its fellow, they together
very much resemble the shape of a funnel.

Use. To draw the rectum upwards after the evacuation of
the fasces, and to assist in shutting it ; to sustain the contents of
the pelvis, and to help in ejecting the semen, urine, and contents
of the rectum ; and, perhaps by pressing upon the veins, to
contribute greatly to the erection of the penis.

— The muscular funnel, formed by the levator ani muscles of
the two sides is antagonized by the action of the sphincter ani,
which, by its connexion with the coccyx and perineal centre
prevents its lower extremity from being drawn upwards.
— When the sphincter is inflamed, and a fluid effused among its
fibres, as is an occasional occurrence in the bowel complaint of
children, the sphincter loses its power, and the levator ani muscles,
unopposed, retract ; and thus by everting the lower margin of the
rectum, contribute mainly to the formation of prolapsus ani. —

PERINEAL MUSCLES OF THE FEMALE. 341

Muscles of the Female Organs of Generation.

The clitoris has one pair.

y
Erector Clitoridis,

Arises from the crus of the os ischium internally, and in its
ascent covers the crus of the clitoris as far up as the os pubis.

Inserted into the upper part of the crus and body of the
clitoris.

Use. Draws the clitoris downwards and backwards ; and
may serve to make the body of the clitoris more tense by
squeezing the blood into it from its crus.

The vagina has one pair.

Sphincter Vagina,

Arises from the sphincter ani, and from the posterior side of
the vagina, near the perineum ; from thence it runs up the
side of the vagina, near its external orifice, opposite to the
nymphcE and covers the corpus cavernosum vaginae.

Inserted into the crus and body or union of the crura
clitoridis.

Use. Contracts the mouth of the vagina, and compresses its
vascular plexus, called corpus cavernosum, or rete mirabik.

Transversus Perinei,

Arises, as in the male, from the fatty cellular membrane which
covers the tuberosity of the os ischium.

Inserted into the upper part of the sphincter ani, and into a
white hardish tough substance in the perineum, between the
lower part of the pudendum and anus.

Use. To sustain and keep the perineum in its proper place.

The anus, as in the male, has a single muscle, and one pair.

Sphincter Ani.

Arises, as in the male, from the skin and fat surrounding the
extremity of the rectum.

Inserted, above, in the white tough substance of the perineum
(jpcrincal centre ;) and below, into the point of the os coccygis.

Use. To shut the passage into the rectum ; and, by pulling

342

MUSCLES OF THE ABDOMINAL CAVITY.

down the perineum, to assist in contracting the mouth of the

Levator Ani,

Arises, as in the male, within the pelvis, and descends along
the inferior part of the vagina and rectum.

Inserted into the perineum^ sphincter ani, extremity of the
vagina and rectum.

Use. To raise the extremity of the rectum upwards, to
contract the inferior part of the rectum, and to assist in con-
tracting and supporting the vagina ; and, perhaps, by pressing
on the veins, to contribute to the distention of the cells of the
clitoris and corpus cavernosum of the vagina.

Muscles situated within the Cavity of the Abdomen.

Fig. 88.*

These consist of a single
muscle, and four pair.

Diaphragma.
This broad thin muscle,
" which makes a complete
septum between the tho-
c rax and abdomen, is con-
cave below and convex
above ; the middle of it on
each side reaching as high
within the thorax of the
skeleton as the fourth rib :
it is commonly divided
into two portions.
1. The superior or,

Greater Muscle of the Dia-
phragm.
Arises, by distinct fleshy

* Thorax of a male.— On the left side the muscles are removed ; on the right
ihey are left in situ, a, a, Cervical and lumbar parts of the spinal column, the
dorsal portion is concealed by the sternum, b. c, c, The true ribs, c', The false
ribs, d, The clavicle, e, Intercostal muscles. /, Last false rib, concealed by
the origin of a part of the greater muscle of the diaphragm, g, The arch

MUSCLES OF THE ABDOMINAL CAVITY. 343

fibres, from the cartilago-ensiformis, from the cartilages of the
seventh, and of all the inferior ribs on both sides. The fibres
from the cartilago-ensiformis, and from the seventh and eighth
ribs, run obliquely upwards and backwards ; from the ninth and
tenth, transversely inwards and upwards, and from the eleventh
and twelfth, obliquely upwards. From these different origins
the fibres run, like radii from the circumference to the centre of
a circle ; and are

Inserted into a cordiform tendon, of a considerable breadth,
which is situated in the middle of the diaphragm, and in which,
therefore, the fibres from opposite sides are interlaced. To-
wards the right side the tendon is perforated, by a triangular
hole, for the passage of the vena cava inferior ; and to the
upper convex part of it the pericardium and mediastinum are
connected.

The inferior, lesser muscle, or

Appendix of the Diaphragm,

Arises from the second, third and fourth lumbar vertebrae, by
eight heads, of which, two in the middle, commonly called its
crura are the longest, and begin tendinous. Between the crura,
the aorta and thoracic duct pass ; and on the outside of these,
the great sympathetic nerves and branches of the vena azygos
perforate the shorter heads. The muscular fibres run obliquely
upwards and forwards, and form in the middle two fleshy col-
umns, which decussate and leave an oval space between them
for the passage of the oesophagus and eighth pair of nerves.
Two bow shaped ligaments are formed on either side at the
lower border of this muscle, as seen in fig. 88.

Inserted, by strong fleshy fibres, into the posterior part of the
middle tendon.

Use. The diaphragm is the principal agent in respiration,
particularly in inspiration : for when it is in action, the fibres,
from their different attachments, endeavor to bring themselves

formed in the interior of the thorax by the diaphragm : the position of this arch
on the right side, is indicated by a dotted line. 7z, Columns, or crura of the
lesser muscles of the diaphragm, arising from the lumbar vertebrae, i, Leva-
tores costarum, longiores, and breviores.

I

344 MUSCLES OF THE ABDOMINAL CAVITY.

into a plain towards the middle tendon, by which the cavity
of the thorax is enlarged, particularly at the sides, where the
lungs are chiefly situated ; and as the lungs must always be
contiguous to the inside of the thorax and upper side of the

Fig. 89 *

diaphragm, the air rushes into them, in order to fill up the
increased space. This muscle is assisted by the two rows of

* The under or abdominal side of t*he diaphragm. J, 2, 3. The greater
muscle ; the figure 1 rests upon the central leaflet of the tendinous centre ; the
number 2 on the left or smallest leaflet ; and number 3 on the right leaflet. 4.
The thin fasciculus which arises from the ensiform cartilage ; a small triangular
space is left on either side of this fasciculus, which is closed only by the serous
membranes of the abdomen and chest. 5. The ligamentum arcuatum exiernum
of the left side. 6. The ligamentum arcuatum internum 7. A small arched
opening occasionally found, through which the lesser splanchnic nerve passes.
8. The right or larger tendon of the lesser muscle ; a muscular fasciculus from
this tendon curves to the left side of the greater muscle between the cesophagea!
and aortic openings. 9. The fourth lumbar vertebra. 10. The left or shorter
tendon of the lesser muscle. 11. The aortic opening occupied by the aorta,
which is cut short off. 12. A portion of the oesophagus issuing through the
cesophageal opening. 13. The opening for the inferior vena cava. in the tendi-
nous centre of the diaphragm. 14. The psoas magnus muscle passing beneath
the ligamentum arcuatum internum ; it has been removed on the opposite side
to show the arch more distinctly. 15. The quadratus lumborum passing be-
neath the ligamentum arcuatum externum ; this muscle has been removed on
the left side.

MUSCLES OF THE ABDOMINAL CAVITY. 345

intercostals, which elevate the ribs, and the cavity of the thorax
is more enlarged. In time of violent exercise, or whatever
cause drives the blood with unusual celerity towards the lungs,
the pectoral muscles, the serrati antici majores, the serrati pos-
tici superiores, and scaleni muscles, are brought into action.
These effect the lateral dilatation of the thorax. And in labo-
rious inspiration, the muscles which arise from the upper part
of the thorax, when the parts into which they are inserted are
fixed, likewise assist. In expiration, the diaphragm is relaxed
and pushed up by the pressure of the abdominal muscles upon
the viscera of the abdomen ; and at the same time that they
press it upwards, they also, together with the sterno-costales
and serrati postici inferiores, pull down the ribs, and are assist-
ed, in a powerful manner, by the elasticity of the cartilages
that join the ribs to the sternum ; by which the cavity of the
thorax is diminished, and the air suddenly pushed out of the
lungs : and, in laborious expiration, the quadrat! lumborum,
sacro-lumbales, and longissimi dorsi, concur in pulling down
the ribs. — The diaphragm, contributes the principal share to
the dilatation of the chest during inspiration. When relaxed,
the diaphragm is arched, and the top of the arch is nearly on
a horizontal level with the anterior portion of the fourth rib, as
seen in fig. 88, page 342. When contracted, the arch is flat-
tened, (though the cordiform tendon itself, is but little depress-
ed,) and the capacity of the thorax is increased, at the same
time that the abdominal viscera are pressed downwards, so as
to produce the protrusion of the abdomen observed during in-
spiration. The abdominal muscles and the diaphragm, usually
antagonize each other, by contracting alternately. Occasionally
they contract in unison, as in straining during defecation, parturi-
tion, &c., and compress the viscera and their contents, between
the two planes which they form, with such force as to give rise
at' times to hernial protrusions.

— In natural tranquil inspiration, the dilatation of the chest is
effected almost wholly by the diaphragm. —
The four pair are,

346 MUSCLES OF THE ABDOMINAL CAVITY.

1. Quadratus Lumborum.

Arises, somewhat broad, tendinous and fleshy, from the poste-
rior part of the spine of the os ilium.

Inserted into the transverse processes of all the vertebrae of the
loins, into the last rib near the spine, and by a small tendon into
the side of the last vertebra of the back.

Use. To move the loins to one side, pull down the last rib.
and, when both act, to bend the loins forwards.

2. Psoas Parvus.

Arises, fleshy, from the sides of the two upper vertebrae of
the loins, and sends off a small long tendon which ends thin and
flat, and is

Inserted into the brim of the pelvis, at the junction of the os
ilium and pubis.

Use. To assist the psoas magnus in bending the loins for-
wards ; and, in certain positions, to assist in raising the pelvis.

N. B. This muscle is very often wanting.

3. Psoas Magnus,

Arises, fleshy, from the side of the body and transverse pro-
cess of the last vertebra of the back ; and, in the same manner,
from those of the loins, by as many distinct slips. — At its
superior portion, this muscle is covered by a thin fibrous
expansion which is attached on the one hand to the points of
the transverse processes, and on the other to the bodies of the
upper lumbar vertebrae. This expansion, the arcus interior
of Senac and Haller (ligamentum arcuatum inter num), sepa-
rates the psoas from the diaphragm. On the outer side of
this is another aponeurotic arch, called ligamentum arcuatum
externum; it passes from the outer extremity of the former,
to the inferior margin of the last rib, embracing in its curve
below, the quadratus lumborum muscle. Both these arches
give origin on their upper margin to fibres of the lesser mus-
cle of the diaphragm, and serve to cut off more effectually
any communication between the thoracic and abdominal
cavities. —

MUSCLES WITHIN THE PELVIS. 347

Inserted, tendinous, into -the trochanter minor of the os
femoris ; and fleshy into that bone, a little below the same
trochanter.

Use. To bend the thigh forwards ; or, when the inferior
extremity is fixed, to assist in bending the body.

4. lliacus Interims.

Arises, fleshy, from the transverse process of the last vertebra
of the loins, from all the inner lip of the spine of the os ilium,
from the edge of that bone between its anterior spinous process
and the acetabulum, and from most of the hollow part of the
ilium. It joins with the psoas magnus, over the pubis, where
it begins to become tendinous ; and is

Inserted along with it on the trochanter minor.

Use. To assist the psoas in bending the thigh, and to bring
it directly forwards.

N. B. The insertion of the two last muscles should not be
traced till the muscles of the thigh are dissected.

Muscles situated within the Pelvis.
Of these there are two pair.

1. Obturator Internus,

Arises from more than one half of the internal circumference
of the foramen thyroideum, formed by the os pubis and ischium,
and from the upper part of the plane of the ischium, where it
joins the ilium. Its inner face is covered by a portion of the
levator ani ; and appears to be divided into a number of fascic-
uli, which unite, and form a roundish tendon, that passes out
of the pelvis, between the posterior sacro-ischiatic ligament and
tuberosity of the os ischium ; where it passes over the capsular
ligament of the thigh bone, it is enclosed as in a sheath, by the
gemini muscles.

Inserted, by a round tendon, into the large pit at the root of
the trochanter major.

Use. To roll the os femoris obliquely outwards.

N. B. The insertion of this muscle should not be traced
until the muscles of the thigh, to which it belongs, are dissected.

348 MUSCLES OF THE BACK.

2. Coccygeus.

Arises, tendinous and fleshy, from the spinous process of the
os ischium, and covers the inside of the posterior sacro-ischiatic
ligament ; from this narrow beginning, it gradually increases
to form a thin fleshy belly, interspersed with tendinous fibres.

Inserted into the extremity of the os sacrum, and nearly the
whole length of the os coccygis laterally.

Use. To support and move the os coccygis forwards, and to
tie it more firmly to the sacrum.

Muscles situated on the Posterior Part of the Truiik.

These may be divided into four layers and a single pair.
The first layer consists of two muscles, which cover almost
the whole posterior part of the trunk.

Trapezius sen Cucullaris,

Arises, by a strong round tendon, from the lower part of the
protuberance in the middle of the os occipitis behind ; and. by
a thin membranous tendon, which covers part of the
splenius and com plexus muscles from the rough curved line
that extends from the protuberance towards the mastoid
process of tire temporal bone ; runs down along the nape of
the neck, where it seems to arise from its fellow, and covers
the spinous processes of the superior vertebrae of the neck ; it
rises from the spinous processes of the two inferior cervical, and
from the spinous processes of all the vertebrae of the back :
adhering tendinous, to, its fellow, the whole length of its origin.
The junction of the tendons form a sort of elliptical expansion
on the back of the neck.

Inserted, fleshy, into the posterior half of the clavicle ;
tendinous and fleshy, into the acromion, and into almost all
the spine of the scapula.

Use. Moves the scapula according to the three different
directions of its fibres : for the upper descending fibres draw it
obliquely upwards ; the middle transverse straight fibres draw

MUSCLES OF THE BACK,

349

it directly backwards ; and the inferior ascending fibres draw it
obliquely downwards and backwards.

Fig. 90.*

* Muscles of the back ; the superficial being shown upon the right, and the
deeper seated on the left side. 1.- The trapezius muscle. 2. The tendinous
portion which with a corresponding" portion in the opposite muscle, forms the
tendinous ellipse on the back of the neck. 3. The acromion process and spine
of the scapula. 4. The latissimus dorsi muscle. 5. The deltoid. 6. The
muscles of the dorsum of the scapula, infra-spinatus, teres minor, and teres
major. 7. The external oblique muscle. 8. The gluteus medius. 9. The
glutei maximi. 10. The levator anguli scapulae. 11. The rhomboideus minor.
12. The rhomboideus major. 13. The splenius capitis ; the muscle immediately
above, and overlaid by the splenius, is the complexus. 14. The splenius colli,
only partially seen ; the common origin of the splenius is seen attached to the
spinous processes below the lower border of the rhomboideus major. 15. The
vertebral aponeurosis. 16. The serratus posticus inferior. 17. The supra-spi-
natus muscle. 18. The infra-spinatus. 19. The teres minor muscle. 20. The
teres major. 21. The long head of the triceps, passing between the teres minor
and major to the upper arm. 22. The serratus magnus, proceeding forwards
from its origin at the base of the scapula. 23. The internal oblique muscle.

30

350 MUSCLES OF THE BACK.

N. B. Where it is inseparably united to its fellow in the
nape of the neck, it is attached to the Ligamentum Nuchce, or
Colli. — This ligament is the representative of an important
elastic ligament in quadrupeds which by its peculiar properties
relieves the action of the muscles, in supporting the heavy
pendant head. The two trapezii taken together, have some
resemblance to the monk's cmvl hanging over the neck, hence
the name of cucullares given to them. When the trapezius
is dissected on both sides, the two muscles represent a trapezium
or diamond shaped quadrangle on the back of the shoulders.
The anterior border of each muscle, forms in the neck the pos-
terior boundary of the posterior triangle of the neck, so impor-
tant to be understood in the operation upon the subclavian artery
above the clavicle. —

2. Latissimus Dorsi,

Arises, by a broad thin tendon, from the posterior part of the
spine of the os ilium, from all the spinous processes of the os
sacrum and vertebrae of the loins, and from the seven inferior
ones of the vertebrae of the back ; also tendinous and fleshy,
from the extremities of the three or four inferior ribs, a little
beyond their cartilages, by as many distinct slips. The inferior
fibres ascend obliquely, and the superior run transversely, over
the inferior angle of the scapula, towards the axilla where they
are collected, twisted, and folded. — Sometimes a few addi-
tional fibres of the muscle, arise from the inferior angle of the
scapula. —

Inserted, by a strong thin tendon, into the inner edge of the
groove for lodging the tendon of the long head of the biceps.

Use. To pull the arm backwards and downwards, and to roll
the os humeri.

N. B. The insertion of this muscle should not be prosecuted
till the muscles of the os humeri, to which it belongs, are
dissected.

The second layer consists of three pair, two on the back, and
one on the neck.
On the back :

MUSCLES OF THE BACK. 351

' 1. Serratus Posticus Inferior,

Arises , by a broad thin tendon, in common with thatj3f the
latissimus dorsi, from the spinal process of the two inferior
vertebrae of the back, and from the three superior vertebrae of
the loins.

Inserted into the lower edge of the four inferior ribs, at a
little distance from their cartilages, by as many distinct fleshy
slips.

Use. To depress the ribs into which it is inserted.

2. Rhomboideus.

This muscle is divided into two portions.

1. Rhomboideus major, arises, tendinous, from the spinous
processes of the five superior vertebrae of the back.

Inserted into all the basis of the scapula below its spine.
Use. To draw the scapula obliquely upwards, and directly
inwards.

2. Rhomboideus minor, arises, tendinous, from the spinous
processes of the three inferior vertebrae of the neck, and from
the ligamentum nuchae.

Inserted into the base of the scapula, opposite to its spine.
Use. To assist the former.
On the neck :

3. Splenius,

Arises, tendinous, from the four superior spinous processes
of the vertebrae of the back : tendinous and fleshy, from the
five inferior of the neck, and adheres firmly to the ligamen-
tum nuchae. At the third vertebra of the neck, the splenii
recede from each other, so that part of the complexus muscle is
seen.

Inserted, by as many tendons, into the five superior transverse
processes of the vertebrae of the neck ; and tendinous and
fleshy, into the superior part of the mastoid process, and into the
os occipitis, where it joins with the root of that process.

Use. To bring the head and upper vertebrae of the neck

352 MUSCLES OF THE BACK.

backwards laterally : and, when both act, to pull the head
directly backwards.

N. B. Albinus divides this muscle into two, viz. That por-
tion which arises from the five inferior spinous processes of the
neck, and is inserted, into the mastoid process and os occipitis,
he calls splenius capitis ; and that portion which arises from
the third and fourth of the ttack, and is inserted into the five
superior transverse processes of the neck, is called by him
splenius collL

The single pair,

Serratus Superior Posticus,

Arises , by a broad thin tendon, from the spinous processes
of the three last vertebrae of the neck, and the two uppermost
of the back.

Inserted into the second, third, fourth, and fifth ribs, by as
many fleshy slips.

Use. To elevate the ribs, and dilate the thorax.

The third layer consists of three pair on the back, and three
on the neck.

Those on the back are,

1. Spinalis Dorsi,

Arises from the spinous processes of the two uppermost ver-
tebrae of the loins, and the three inferior of the back, by as
many tendons.

Inserted into the spinous processes of the nine uppermost
vertebrae of the back, except the first, by as many tendons.

Use. To erect and fix the vertebrae, and to assist in raising
the spine.

2. Longissimus Dorsi,

Arises, tendinous without, and fleshy within, from the side,
and all the spinous processes of the os sacrum ; from the poste-
rior spine of the os ilium ; from all the spinous processes, and
from the roots of the transverse processes of the vertebrae of the
loins.

MUSCLES OF THE BACK AND NECK. 353

Inserted into all the transverse processes of the vertebrae of
the back, chiefly by small double tendons ; also, by a tendinous
and fleshy slip, into the lower edge of all the ribs, except the
two inferior, at a little distance from their tubercles.

Use. To extend the vertebrae, and to raise and keep the trunk
of the body erect.

N. B. From the upper part of this muscle, there runs up a
round fleshy portion which joins with the cervicalis descendens.

3. Sacro-Lumbalis,

Arises, in common with the longissimus dorsi.

Inserted into all the ribs, where they begin to be curved
forwards, by as many long and thin tendons ; and,

From the upper part of the six or eight lower ribs, arise as
many bundles of thin fleshy fibres, which soon terminate in
the inner side of this muscle, and are named musculi ad sacro-
lumbalem accessorii.

Use. To pull the ribs down, and assist in erecting the trunk
of the body.

N. B. There is a fleshy slip which runs from the upper part
of this muscle into the fourth, fifth, and sixth transverse pro-
cesses of the vertebrae of the neck, by three distinct tendons :
it is named cervicalis descendens ; and its use is to turn the neck
obliquely backwards, and to one side.

On the neck are,

1. Complexus,

Arises from the transverse processes of the seven superior
vertebrae of the back, and four inferior of the neck, by as many
distinct tendinous origins ; in its ascent, it receives a fleshy slip
from the spinous process of the first vertebra of the back. From
these different origins it runs upwards, and is every where
intermixed with tendinous fibres.

Inserted, tendinous and fleshy, into the inferior edge of the
protuberance in the middle of the os occipitis, and into a part
of the curved line that runs forwards from that protuberance.
30*

354 MUSCLES OF THE BACK AND NECK.

Use. To draw the head backwards, and to one side, and
when both act, to draw the head directly backwards.

N. B. The long portion of this muscle that is situated next
the spinous processes, lies more loose, and has a roundish tendon
in the middle of it : for which reason Albinus calls it biventer

cervicis.

•

2. Trachelo-Mastoideusj

Arises from the transverse processes of the three uppermost
vertebrae of the back, and from the five lowermost of the neck,
(where it is connected to the transversalis cervicis,) by as many
thin tendons, which unite into a belly, and run up under the
splenius.

Inserted into the middle of the posterior side of the mastoid
process, by a thin tendon.

Use. To assist the complexus ; but it pulls the head more
to one side.

3. Levater Scapulae,

Arises, tendinous and fleshy, from the transverse processes
of the five superior vertebrae of the neck, by as many distinct
slips, which soon unite to form a muscle that runs downwards
and outwards.

Inserted, fleshy, into the superior angle of the scapula.

Use. To pull the scapula upwards and a little forwards.

The fourth layer consists of two pair* on the back, two on
the posterior part of the neck, four small pair situated immedi-
ately below the posterior part of the occiput, and three on the
side of the neck.

On the back are,

1. Scmi-Spinalis Dorsi,

Arises, from the transverse processes of the seventh, eighth,
ninth, and tenth vertebrae of the back, by as many distinct
tendons, which soon grow fleshy, and then become tendinous :
and are

Inserted into the spinous processes of all the vertebrae of

MUSCLES OF THE BACK AND NECK.

355

the back above the eighth, and into the two lowermost of the
neck, by as many tendons.

Use. To extend the spine obliquely backwards.

2. Multifidus Spina,
Arises from the side and spinous processes of the os sacrum,

Fig. 91*

and from the posterior part of the os
ilium, where it joins with the sacrum ;
from all the oblique and transverse
processes of the vertebra of the loins ;
from all the transverse processes of
the vertebrae of the back, and from
those of the neck, except the three
first, by as many distinct tendons,
which soon grow fleshy, run in an
oblique direction ; and are

Inserted, by distinct tendons, into all
the spinous processes of the vertebras
of the loins, of the back, and of the
neck, except the first.

Use. When the different portions
of this muscle act on one side, they
extend the back obliquely, or move it
laterally ; but if they act together on
both sides, they extend the vertebrae
backwards.

On the posterior part of the neck
are,

* Deep seated muscles of the back. 1. The common origin of the erector
spinae muscle. Under which term is included three muscles, the sacro-lumba-
jis, longissimus dorsi, and spinalis dorsi. 2. The sacro-lumbalis. 3. The
longissimus dorsi. 4. The spinalis dorsi. 5. The cervicalis ascendens. 6.
The transversalis colli. 7. Th.e trachelo-mastoideus. 8. The complexus. 9.
The transversalis colli, showing its origin. 10. The semispinalis dorsi. 11.
The semispinalis colli. 12. The rectus posticus minor. 13. The rectus posticus
major. 14. The obliquus superior. 15. The obliquus inferior. 16. The multi-
fidus spinae. 17. The levatores costarum. 18. Intertransversales. 19. The
quadratus lumborum.

356 MUSCLES OF THE BACK AND NECK.

1. Semi-Spinalis Colli,

Arises from the transverse processes of the uppermost six
vertebrae of the back, by as many distinct tendons ascending
obliquely under the com plexus.

Inserted into the spinous processes of all the vertebrae of
the neck, except the first and the last.

Use. To extend the neck obliquely backwards.

2. Transversalis Cotti,

Arises from the transverse processes of the five uppermost
vertebrae of the back, by as many tendinous and fleshy origins ;
runs between the trachelo mastoideus, and splenius colli and
cervicalis descendens.

Inserted into the transverse processes of all the cervical ver-
tebrae, except the first and the last.

Use. To turn the neck obliquely backwards, and a little to
one side.

Below the posterior part of the occiput are,

1. Rectus Capitis Posticus Major,

Arises, fleshy, from the external part of the spinous process
of the second vertebra of the neck, and grows broader in its
ascent, which is not straight, but obliquely outwards.

Inserted, tendinous and fleshy, into the os occipitis, near the
rectus capitis lateralis, and the insertion of the obliquus capitis
superior.

Use. To pull the head backwards, and to assist a little in its
rotation.

2. Rectis Capitis Posticus Minor.

Arises, by a narrow beginning, close to its fellow, from a
little protuberance in the middle of the back part of the first
vertebra of the neck, its outer edge being covered by the rectus
major.

Inserted, somewhat broad, into the sides of a dimple in the
os occipitis, near its foramen magnum.

Use. To assist the rectus major in moving the head back-
wards.

MUSCLES OF THE BACK AND NECK. 357

3. Obliquus Capitis Superior.

Arises from the transverse process of the first vertebra of the
neck.

Inserted, tendinous and fleshy, into the os occipitis behind
the back part of the mastoid portion of the temporal bone, and
under the insertion of the complexus muscle.

Use. To draw the head backwards.

4. Obliquus Capitis Inferior.

Arises, fleshy, from the spinous process of the second verte-
bra of the neck, its whole length ; and, forming a thick fleshy
belly, is

Inserted into the transverse process of the first vertebra of
the neck.

Use. To give a rotary motion to the head.

On the side of the neck are,

1. Scalenus Anticus,

Arises from the fourth, fifth, and sixth transverse processes of
the first vertebra of the neck, by as many tendons.

Inserted, tendinous and fleshy, into the upper side of the first
rib near its cartilage.

2. Scalenus Medius,

Arises from all the transverse processes of the vertebra of the
neck, by as many strong tendons ; the nerves to the superior
extremity pass between it and the former.

Inserted into the upper and outer part of the first rib, from its
root, to within the distance of an inch from its cartilage.

3. Scalenus Posticus,

Arises from the fifth and sixth transverse processes of the
vertebrae of the neck.

Inserted into the upper edge of the second rib, not far from
the spine.

Use of the three scaleni ; to bend the neck to one side ; or,

358 MUSCLES OF THE BACK AND NECK.

when the neck is fixed, to elevate the ribs, and to dilate the
thorax.

There are a number of small muscles situated between the
spinous and transverse processes of contiguous vertebrae ; which
are accordingly named,

1. Interfpinales Cotti.

The space between the spinous processes of the vertebrae of
the neck, most of which are bifurcated, is filled up with these
fleshy portions ; each of which

Arises, double, from the spinous process of the cervical
vertebra below, and ascends to be

Inserted, in the same manner, into the spinous process of the
vertebra above. They are five in number.

Use. To draw these processes nearer to each other.

2. Intertransversales Colli.

They begin from the transverse process of the first vertebra
of the back, and fill up the spaces between the transverse
processes of the vertebrae of the neck, which are likewise
bifurcated ; and, consequently, there are six distinct double
muscles, which

Arise from the inferior transverse process of each vertebra of
the neck, and first of the back, and are

Inserted into the transverse processes next above.

Use. To draw these processes towards each other, and turn
the neck a little to one side.

Interspinales Dor si et Lumborum, and the Intertransver-
sales Dorsi,

Are rather small tendons than muscles, serving to connect the
spinal and transverse processes.

Intertransversales Lumborum,

Are four distinct small bundles of flesh, which fill up the space
between the transverse processes of the vertebrae of the loins,
and serve to draw them towards each other.

MUSCLES OF THE SUPERIOR EXTREMITIES. 359

MUSCLES OF THE SUPERIOR EXTREMITIES.

THESE may be divided into the muscles that are situated on
the scapula, on the os humeri, on the cubit or forearm, and on
the hand.

Muscles situated on the Scapula.

These are called muscles of the os humeri ; and are three
behind, one along its inferior costa, two before, and one beneath
it.

Behind are,

1 . Supra-spinatus ,

Arises, fleshy, from all that part of the base of the scapula
that is above its spine ; also from the spine and superior costa ;
passes under the acromion, and adheres to the capsular ligament
of the os humeri.

Inserted, tendinous, into that part of the large protuberance
on the head of the os humeri, that is next the groove for lodging
the tendon of the long head of the biceps.

Use. To raise the arm upwards ; and, at the same time, to
pull the capsular ligament from between the bones, that it may
not be pinched.

2. Infra-spinatus,

Arises, fleshy, from all that part of the base of the scapula
that is between its spine and inferior angle ; and from the spine
as far as the cervix of the scapula. The fibres ascend and
descend obliquely towards a tendon in the middle of the mus-
cle, which runs forwards, and adheres to the capsular ligament.

Inserted, by a thick and short tendon, into the upper and
middle part of the large protuberance on the head of the os
humeri.

Use. To roll the humerus outwards : to assist in raising, and
in supporting it when raised ; and to pull the ligament from
between the bones.

360 MUSCLES SITUATED ON THE SCAPULA.

JV. J5. These two muscles are covered with a tendinous
membrane, from which a number of their fleshy fibres arise.
It serves besides to strengthen their actions, and keeps them
from swelling too much outwardly when in action.

3. Teres Minor,

Arises, fleshy, from all the* round edge of the inferior costa ol
the scapula, and runs forwards along the inferior edge of the
infra-spinatus muscle, and adheres to the ligament.

Inserted, tendinous, into the back part of the large protube-
rance on the head of the os humeri, a little behind and below
the termination of the last named muscle.

Use. To roll the humerus outwards, to draw the humerus
backwards ; and to prevent the ligament from being pinched
between the bones.

Along the inferior costa of the scapula is,

Teres Major,

Arises, fleshy, from the inferior angle of the scapula, and from
all that portion of its inferior costa that is rough and thicker
than the rest ; its fleshy fibres are continued over part of the
infra-spinatus muscle, to which they firmly adhere.

Inserted, by a broad, short, and thin tendon, into the ridge at
the inner side of the groove for lodging the tendon of the long
head of the biceps, along with the latissirnus dorsi.

Use. To roll the humerus inwards, and to draw it backwards
and downwards.

The two before the scapula are,

1. Deltoides,

Arises, fleshy, from all the posterior part of the clavicle
that the pectoralis major does not occupy ; tendinous and fleshy,
from the acromion, and lower margin of almost the whole
spine of the scapula opposite to the insertion of the cucullaris
muscle ; from the origins it runs in three different directions,
i. e. from the clavicle outwards and downwards ; from the

MUSCLES SITUATED ON THE SCAPULA. 361

spine of the scapula outwards, forwards, and downwards ; and
from the acromion, straight downwards ; and is composed of a
number of fasciculi, which form a strong fleshy muscle^ that
covers the anterior part of the joint of the os humeri.

Inserted, tendinous, into a rough protuberance in the outer
side of the os humeri, near its middle, where the fibres of this
muscle intermix with some part of the brachialis externus.

Use. To pull the arm directly outwards and upwards, and
a little forwards or backwards, according to the different direc-
tions of its fibres.

.

2. Coraco-Brachialis,

Arises, tendinous and fleshy, from the forepart of the coracoid
process of the scapula ; adhering in its descent, to the short
head of the biceps.

Inserted, tendinous and fleshy, about the middle of the
internal part of the os humeri, near the origin of the third
head of the triceps, called brachialis externus, where it sends
down a thin tendinous expansion to the internal condyle of the
os humeri.

Use. To raise the arm upwards and forwards.

N. B. There passes a nerve through this muscle, called
musculo cutaneus.

The one beneath the scapula is,

Subscapularis,

Arises, fleshy, from all the base of the scapula, internally,
and from its superior and inferior costae, being composed of a
number of tendinous and fleshy fasciculi, which make prints
on the bone ; they all join together, fill up the hollow of the
scapula, and pass over the joint, adhering to the capsular
ligament.

Inserted, tendinous, into the upper part of the internal protu-
berance at the head of the os humeri.

Use. To roll the humerus inwards, and to draw it to the side
of the body ; and to prevent the capsular ligament from being
pinched.

31

362

MUSCLES SITUATED ON THE OS HUMERI.

Muscles situated on the Os Humeri.
These are called

Muscles of the Cubit or Forearm.

They consist of two before, and two behind.

Before are,

•

Fig. 92 * 1. Biceps Flexor Cubiti,

Arises, by two heads. The first and
outermost called longus, begins tendinous
from the upper edge of the glenoid cavity
of the scapula, passes over the head of
the os humeri within the joint ; and, in
its descent without the joint, is enclosed in
a groove near the head of the os humeri,
by a membranous ligament that proceeds
from the capsular ligament and adjacent
tendons. The second or innermost head,
called brevis, arises tendinous and fleshy,
from the coracoid process of the scapula,
in common with the coraco-brachialis
muscle. A little below the middle of
the forepart of the os humeri, these heads
unite.

Inserted, by a strong roundish tendon,
into the tubercle on the upper end of the
radius internally.

Use. To turn the hand supine, and to bend the forearm.
.ZV. B. At the bending of the elbow, where it begins to grow
tendinous, it sends off an aponeurosis which covers all the
muscles on the inside of the forearm, and joins with another
tendinous membrane, which is sent off from the triceps ex-
tensor cubiti, covers all the muscles on the outside of the

* The muscles of the anterior aspect of the upper arm. 1. The coracoid
process of the scapula. 2. The coraco-clavicular ligament (trapezoid), passing
upwards to the scapular end of the clavicle. 3. The coraco-acromial ligament,
passing outwards to the acronaion. 4. The subscapularis muscle. 5. The
teres major. 6. The coraco-brachialis. 7. The biceps. 8. The upper end of
the radius. 9. The brachialis anticus. 10. The internal head of the triceps.

MUSCLES SITUATED ON THE OS HUMERI.

363

forearm, and a number of the fibres, from opposite sides,
'decussate each other. It serves to strengthen the muscles, by
keeping them from swelling too much outwardly, when in
action ; and a number of their fleshy fibres take their origin
from it.

2. Brachialis Interims, ."r fit*

Arises, fleshy, from the middle of the os humeri, at each side
of the insertion of the deltoid muscle, covering all the inferior
and forepart of this bone, runs over the joint and adheres firmly
to the ligament.

Fig. 93.* Inserted, by a strong tendon, into

the coronoid process of the ulna.

Use. To bend the forearm, and to
prevent the capsular ligament of the
joint from being pinched.
Behind, are

1. Triceps Extensor Cubiti,

Arises, by three heads ; the first call-
ed longus, somewhat broad and tendi-
nous, from the inferior costa of the
scapula, near its cervix. The second
head, called brevis, arises by an acute,
tendinous, and fleshy beginning, from
the back part of the os humeri, a little
below its head, outwardly. The third,
called brachiatis externus, arises by
an acute beginning, from the back part
of the os humeri. These three heads
unite lower than the insertion of the
teres major, and cover the whole posterior part of the humerus,
from which they receive addition in their descent.

* A posterior view of the arm, showing the triceps extensor cubiti muscle.
1. Its external head called brevis. 2. Its long or scapular head. 3. Its inter-
nal head, called in contradistinction with a muscle on the front of the arm,
brachialis externus. 4. The olecranon process of the ulna. 5. The radius. 6.
The capsular ligament of the shoulder joint.

364 MUSCLES ON THE ANTERIOR PART OF THE FOREARM.

Inserted into the upper and external part of the process oJ
the ulna, called olecranon, and partly into the condyles of the
os humeri, adhering firmly to the ligament.

Use. To extend the forearm.

2. Anconeus,

Arises, tendinous, from tfre posterior part of the external
condyle of the os humeri ; it soon grows fleshy, and is continued
from the third head of the triceps.

Inserted, fleshy, and thin into a ridge on the outer and pos-
terior edge of the ulna, being continued some way before the
olecranon, and covered with a tendinous membrane.

Use. To assist in extending the forearm.

Muscles situated on the Forearm.

%

These may be divided into three classes, viz.

1. The muscles which bend and extend the wrist, and of course the whole hand.

2. Those which bend and extend the fingers exclusively.

3. Those which act on the radius so as to roll it backwards and forwards on the
ulna ; which are called supinators and pronators.

The flexors both of the wrist and fingers, and the pronators, lie on the front of
the forearm. The extensors and the supinators on the back.

The flexors generally originate from the internal condyle of the os humeri, and
the parts adjacent to it ; the extensors from the external condyle of the same
bone, and the parts which are near it.

In the following description they are arranged in the order in which they occur
in the dissection of the arm ; beginning with those which originate with the
internal condyle, without regard to their particular functions.

Muscles on the anterior part of the Forearm.

1. Palmaris Longus,

Arises, tendinous, from the internal condyle of the os
humeri, soon grows fleshy, and, after a short progress sends
off a long slender tendon.

Inserted into the ligamentum carpi annulare, 'and into a
tendinous membrane that is expanded on the palm of the
hand, named aponeurosis palmaris ; which, above, begins
at the transverse or annular ligament of the wrist, and, below, is
fixed to the roots of the fingers.

MUSCLES ON THE ANTERIOR PART OF THE FOREARM.

365

Use. To bend the hand, and to stretch the membrane that
is expanded on the palm. ^

N. B. This muscle is sometimes wanting, but the aponeu-
rosis palmaris is always to be found.

2. Pronator Radii Teres,

Arises, fleshy, from the internal condyle of the os humeri,
Fig. 94.* and tendinous from the coronoid process of
the ulna.

Inserted, thin, tendinous, and fleshy, into
the middle of the posterior part of the radius.
Use. To roll the radius, together with the
hand, inwards,

3. Flexor Carpi Radialis,
Arises, tendinous and fleshy, from the
internal condyle of the os humeri, and from
the anterior part of the upper end of the
ulna, where it firmly adheres to the pronator
radii teres.

Inserted, by a flat tendon, into the fore
and upper part of the metacarpal bone that
sustains the forefinger, after running through
a fossa in the os trapezium.

Use. To bend the hand, and to assist in
its pronation.

4. Flexor Carpi Ulnaris,
Arises, tendinous, from the internal con-
dyle of the os humeri. It has, likewise, a
small fleshy beginning from the outer side

* Superficial layer of muscles of the fore-arm. 1. The lower part of the
biceps, with its tendon. 2. A part of the brachialis anticus, seen beneath the
biceps. 3. A part of the triceps. 4. The pronator radii teres. 5. The flexor
carpi radialis. 6. The palmaris longus. 7. One of the fasciculi of the flexor
sublimis digitorum ; the rest of the muscle is seen beneath the tendons of the
palmaris longus and flexor carpi radialis. 8. The flexor carpi ulnaris. 9. The
palmar fascia. 10. The palmaris brevis muscle. 11. The abductor pollicis
muscle. 12. One portion of the flexor brevis pollicis ; the leading line crosses
a part of the abductor pollicis. 13. The supinator longus muscle. 14. The
extensor ossis metacarpi, and extensor primi internodii pollicis, curving around
the lower border of the fore-arm.

31*

366 MUSCLES ON THE ANTERIOR PART OF THE FOREARM.

of the olecranon, between which, and the origin from the
condyle, there is a space left, through which the ulnar nerve
passes to the forearm ; 'and a number of its fleshy fibres arise
from the tendinous membrane that covers the forearm.

Fig. 95.* Inserted, by a short strong tendon, into

the os pisiforme. At a little distance from
its insertion, a small ligament is sent off to
the metacarpal bone that sustains the little
finger.

Use. To assist the former in bending the
arm.

5. Flexor Sublimis Perforatus,

Arises, tendinous and fleshy, from the
.internal condyle of the os humeri ; tendin-
ous from the coronoid process of the ulna,
near the edge of the cavity that receives the
head of the radius ; fleshy from the tubercle
of the radius ; and membranous and fleshy
from the middle of the forepart of the
radius, where the flexor pollicis longus
arises. Its fleshy belly sends off four round
tendons before it passes under the ligament
of the wrist.

Inserted into the anterior and upper part
of the second bone of each finger, being near
the extremity of the first bone, and divided
for the passage of the perforans.
Use. To bend the second joint or phalanx of the fingers.

6. Flexor Profundus Perforans,
Arises, fleshy, from the external side, and upper part of the

* The deep layer of muscles on the forearm, i. The internal lateral liga-
ment of the elbow joint. 2. The anterior ligament. 3. The orbicular ligament
of the head of the radius. 4. The flexor profundus digitorum muscle. 5. The
flexor longus pollicis. 6. The pronator quadratus. 7. The adductor pollicis
muscle. 8. The dorsal interosseous muscle of the middle finger, and palmar
interosseous of the ring finger. 9. The dorsal interosseous muscle of the ring
linger and palmar interosseous of the little finger.

MUSCLES ON THE BACK OF THE FOREARM. 367

ulna, for some way downwards, and from a large share of the
interosseous ligament. It splits into four tendons, a little before
it passes under the ligamentum carpi annulare ; and these pass
through the slits in the tendons of the flexor sublimis.

Inserted into the fore and upper part of the third or last bone
of all the four fingers.

Use. To bend the last joint of the fingers.

7. Flexor Longus Pollicis Manus,

Arises, by an acute fleshy beginning, from the upper part of
the radius, immediately below its tubercle, and is continued down
for some space on the forepart of this bone. It has likewise
generally another origin from the internal condyle of the os
humeri, which forms a distinct fleshy slip, that terminates near
the upper part of the origin from the radius.

Inserted into the last joint of the thumb, after having passed
its tendon under the ligament of the wrist.

Use. To bend the last joint of the thumb.*

8. Prenator Radii Qwdratiu,

Arises, broad, tendinous, and fleshy from the lower and inner
part of the ulna ; the fibres run transversely, to be

Inserted into the lower and anterior part of the radius, oppo-
site to its origin.

Use. To turn the radius, together with the hand, inwards.

Muscles of the External Side and Back of the Arm.
1 . Supinator Radii Longus,

Arises, by an acute and fleshy origin, from the external ridge
of the os humeri, above the external condyle, nearly as far up as
the middle of that bone.

* The thumb has but one flexor muscle on the front of the arm, although it
has three extensors on the back part. — No animal but man has a distinct
flexor lengus pollicis muscle. In the monkey even, its place is supplied by a
branch of the communis digitorum tendons ; man only can bring the thumb in
direct opposition to the fingers, and make the hand a perfect instrument of
prehension. — P.

368

MUSCLES ON THE BACK OF THE FOREARM.

Fig. 96.<

Inserted into the outer side of the infe-
rior extremity of the radius.

Use. To roll the radius outwards, and
consequently the palm of the hand up-
wards.

2. Extensor Carpi Radialis Longior,
Arises, broad, thin, and fleshy, immedi-
ately below the supinator radii longus, from
the lower part of the external ridge of the os
humeri, above its external condyle.

Inserted, by a round tendon, into the pos-
terior and upper part of the metacarpal bone
that sustains the fore-finger.

Use. To extend and bring the hand back-
wards.

3. Extensor Carpi Radialis Brevior,
Arises, tendinous, from the external con-
dyle of the os humeri, and from the ligament
that connects the radius to it, and runs along
the outside of the radius.

Inserted, by a round tendon, into the
upper and back part of the metacarpal bone
that sustains the middle finger.

Use. To assist the last mentioned muscle.

4. Extensor Carpi Ulnaris,
Arises, tendinous from the external condyle of the os humeri,

* The superficial layer of muscles on the posterior aspect of the fore-arm.

I. The lower part of the biceps. 2. Part of the brachialis anticus. 3. The
lower part of the triceps, inserted into the olecranon. 4. The supinaver longus,
5. The extensor carpi radialis longior. 6. The extensor carpi radialis brevier.
7. The tendons of insertion of these two muscles. 8. The extensor communis
digitorum. 9. The extensor minimi digiti. 10. The extensor carpi ulnaris.

II. The anconeus. 12. Part of the flexor carpi ulnaris. 13. The extensor ossis
metacarpi and extensor primi internodii muscle, lying together. 14. The
extensor secundi internodii ; its tendon is seen crossing the two tendons of the
extensor carpi radialis longior and brevior. 15. The posterior annular ligament.
The tendons of the common extensor are seen upon the back of the hand, and
their mode of distribution on the dorsum of the lingers.

MUSCLES ON THE BACK OF THE FOREARM. 369

and in its progress, fleshy, from the middle of ihe ulna, where
it passes over the ulna. Its round tendon is enclosed by a
membranous sheath, in a groove which is situated at the ex-
tremity of the ulna.

Inserted, by its round tendon, into the posterior and upper
part of the metacarpal bone that sustains the little finger.

Use. To assist the former in extending the hand.

f
)g, froi

5. Extensor Digitorum Communis,

Arises, by an acute, tendinous, and fleshy beginning, from
the external condyle of the os humeri, where it adheres to the
supinator radii brevis. Before it passes under the ligamentum
carpi annulare externum, it splits into four tendons ; some of
which may be divided into several smaller ; and about the fore-
part of the metacarpal bones they remit tendinous filaments to
each other.

Inserted into the posterior part of all the bones of the four
fingers, by a tendinous expansion.

Vse. To extend all the joints of the fingers.

6. Supinator Radii Brevis,

Arises, tendinous, from the external condyle of the os humeri ;
tendinous and fleshy, from the external and upper part of the
ulna, and adheres firmly to the ligament that joins these two
bones.

Inserted, into the head, neck, and tubercle of the radius, near
the insertion of the biceps, and into the ridge running from that
downwards and outwards.

Use. To roll the radius outwards, and so bring the hand
supine.

7. Indicator,

Arises, by an acute fleshy beginning, from the middle of the
posterior part of the ulna ; its tendon passes under the same
ligament with the extensor digitorum communis, with part of
which it is

Inserted into the posterior part of the fore-finger.

Use. To extend the fore-finger separately.

370 MUSCLES ON THE BACK OF THE FOREARM.

8. Extensor Ossis Metacarpi Pollicis Manus.
Arises, fleshy, from the middle and posterior part of the ulna,
immediately below the insertion of the anconeus muscle, from
Fig. 97.* the posterior part of the middle of the radius,
and from the interosseous ligament.

Inserted, generally by two tendons, into
the os trapezium, and upper back part of the
metacarpal bone of the thumb, and often
joins with the adductor pollicis.

Use. To extend the metacarpal bone of
the thumb, outwardly.

9. Extensor Primi Internodii, (Ext.

Major Pollicis Manus,)

Arises, fleshy, from the posterior part of
the ulna near the former muscle, and from
the interosseous ligament.

Inserted, tendinous, into the posterior part
of the first bone of the thumb ; and a part of
it may be traced as far as the second bone.

Use. To extend the first bone of the
thumb obliquely outwards.

10. Extensor Secundi Internodii, (Ext.

Minor Pollicis Manus,)

Arises, by an acute, tendinous, and fleshy
beginning, from the middle back part of the ulna, and from the
interosseous ligament ; its tendon runs through a small groove at
the inner and back part of the lower end of the radius.

Inserted into the last bone of the thumb.

Use. To extend the last joint of the thumb obliquely back-
wards.

* The deep layer of muscles on the posterior aspect of the fore-arm. 1. The
lower part of the humerus. 2. The olecranon. 3. The ulna. 4. The anconeus
muscle. 5. The supinator brevis muscle. 6. The extensor ossis metacarpi
pollicis. 7. The extensor primi internodii pollicis. 8. The extensor secundi
internodii pollicis. 9. The extensor indicis. 10. The first dorsal interosseous
muscle. The other three dorsal interossei are seen between the metacarpal
bones of their respective fingers.

MUSCLES ON THE PALM OF THE HAND. 371

Muscles on the Palm of the Hand,.

To obtain a full view of the muscles situated on the palm of the hand, it will
be necessary to remove the annular or transverse ligament, which is stretched
across from the projecting points of the pisiform and unciform bones on the
inside of the wrist to the scaphoid and trapezium on the outside j for the pur-
pose of retaining the tendons of the flexor muscles in their proper situation.
And also, to remove from the palm of the hand the aponeurosis palmaris,
which has been described with the palmaris longus muscle.

1. Palmaris Brevis.

Arises from the ligamentum carpi annulare, and the apon-
eurosis that is expanded on the palm of the hand.

Inserted, by small bundles of fleshy fibres, into the skin and
fat that cover the adductor minimi digiti, and into the os pisi-
forme.

Use. To assist in contracting the palm of the hand.

2. Abductor Pollicis Manus,

Arises, by a broad tendinous and fleshy beginning, from the
ligamentum carpi annulare, and from the os trapezium.

Inserted^ tendinous, into the outer side of the root of the
first phalanx of the thumb.

Use. To draw the thumb from the fingers.

3. Flexor Ossis Metacarpi Pollicis, or Opponens Pollicis,

Arises, fleshy, from the os trapezium and ligamentum carpi
annulare, lying under the adductor pollicis.

Inserted, tendinous and fleshy, into the under and anterior
part of the metacarpal bone of the thumb.

Use. To bring the thumb inwards, opposite to the other
finger.

4. Flexor Brevis Pollicis Manus,

Is divided into two portions by the tendon of the flexor
longus pollicis, and is placed beneath the adductor, and at the
side of the opponens. It is divided into two heads. The first
arises fleshy from the volar sides of the trapezium, trapezoides,
and from the contiguous part of the internal surface of the
annular ligament. The second head arises from the magnum,

372

MUSCLES ON THE PALM OF THE HAND.

unciforme, and from the base of the metacarpal bone of the
middle finger.

Inserted) by the first head into the outer sesamoid bone, and
by the second into the inner sesamoid bones. These bones
act the parts of patellae, by having a tendinous connexion with
the first phalanx of the thumb.

Use. To bend the first joirft of the thumb.

5. Adductor Potticis Manus,

Fig. 98.*

Arises, fleshy, from almost the
whole length of the metacarpal
bone that sustains the middle
finger ; from thence its fibres are
collected together.

Inserted, tendinous, into the
inner part of the root of the first
phalanx of the thumb.

Use. To pull the thumb to-
wards the fingers.

There are four small flexors,
called, from their form,

6. Lumbricales,
Which arise, thin and fleshy,
from the outside of the tendons
of the flexor profundus, a little
above the lower edge of the ligamentum carpi annulare.

* The muscles of the hand. *1. The annular ligament. 2, 2. The origin
and insertion of the abductor pollicis muscle ; the middle portion has been
removed. 3. The flexor ossis metacarpi, or opponens pollicis. 4. One portion
of the flexor brevis pollicis. 5. The deep portion of the flexor brevis pollicis.
6. The adductor pollicis. 7, 7. The lumbricales muscles, arising from the deep
flexor tendons, upon which the numbers are placed. The tendons of the flexor
sublimis have been removed from the palm of the hand. 8. One of the tendons
of the deep flexor, passing between the two terminal slips of the tendon of the
flexor sublimis to reach the last phalanx. 9. The tendon of the flexor longus
pollicis, passing between the two portions of the flexor brevis to the last pha-
lanx. 10. The abductor minimi digiti. 11. The flexor brevis minimi digiti.
The edge of the flexor ossis metacarpi, or adductor minimi digiti, is seen pro-
jecting beyond the inner border of the flexor brevis. 12. The prominence of
the pisiform bone. 13. The first dorsal interosseous muscle.

MUSCLES ON THE PALM OF THE HAND. 373

Inserted, by long slender tendons, into the outer sides of the
broad tendons of the interossei muscles, about the middle of the
first joint.

Use. To increase the flexion of the fingers while ;the long
flexors are in full action.

7. Adductor Metacarpi Minimi Digiti Manus,

Arises, fleshy from the thin edge of the os unciforme, and
from that part of the ligament of the wrist next to it.

Inserted, tendinous, into the inner side and anterior part of the
metacarpal bone of this finger.

Use. To bend and bring the metacarpal bone of this finger
towards the wrist.

8. Flexor Parvus Minimi Digiti,

Arises, fleshy, from the outer side of the os unciforme, and
from the ligament of the wrist which joins with that bone.

Inserted, by a roundish tendon, into the inner and anterior
part of the upper end of the first bone of this finger.

Use. To bend the little finger, and assist the adductor.

9. Abductor Minimi Digiti Manus.

Arises, fleshy, from the os pisiforme, and from that part of the
ligamentum carpi annulare next it.

Inserted, tendinous, into the inner side of the upper end of
the first bone of the little finger.

Use. To draw this finger from the rest.

The spaces between the metacarpal bones are occupied by
muscles, called, from their situation, interosseous. The four
following are to be seen on the palm of the hand.

Anterior Interosseous Muscles.

1. Prior Indicis.

Arises, tendinous and fleshy, from the upper and outer part of
the metacarpal bone that sustains the fore-finger.

Inserted into the outside of that part of the tendinous
32

374 MUSCLES ON THE BACK OF THE HAND.

expansion from the extensor digitorum communis, which covers
the posterior part of the fore-finger.

Use. To draw the fore-finger outwards towards the thumb,
and extend it obliquely.

2. Posterior Indicis.

Arises tendinous and fleshy f from the root and inner part of
the metacarpal bone that sustains the fore-finger.

Inserted into the inner side of the tendinous expansion which
is sent off from the extensor digitorum communis, along the
posterior part of the fore-finger.

Use. To extend the fore-finger obliquely, and to draw it
inwards.

3. Prior Annular is.

Arises, from the root of the outside of the metacarpal bone
that sustains the ring finger.

Inserted into the outside of the tendinous expansion of the
extensor digitorum communis which covers the ring finger.

Use. To extend and pull the ring finger towards the thumb.

4. Interosseous Auricularis,

Arises, from the root and outer side of the metacarpal bone
of the little finger ; and is

Inserted into the outside of the tendinous expansion of the
extensor digitorum communis, which covers the posterior part of
the little finger.

Use. To extend and draw the little finger outwards.

On the back of the hand three muscles of the same kind are
to be seen, which also appear on the palm.

Posterior Interosseous Muscles.

, 1. Prior Medii,

Arises, by two origins, from the root of the metacarpal bones
that sustain the fore and middle fingers externally, and next each
other : runs along the outside of the middle finger ; and, being
conspicuous on both sides of the hand, is

MUSCLES OF THE OS FEMOR1S. 375

Inserted into the outside of the tendinous expansion from the
extensor digitorum communis, which covers the posterior jpart of
the middle finger.

Use. To extend and to draw the middle finger outwards.

2. Posterior Medii,

Arises, by two origins, from the roots of the metacarpal bones
next each other, that sustain the middle and ring fingers.

Inserted into the inside of the tendinous expansion from the
extensor digitorum communis, which runs along the posterior part
of the middle finger.

Use. To extend and draw the middle finger inwards.

3. Posterior Annularis,

Arises, by two origins, from the roots of the metacarpal bones
that sustain the ring and little fingers, next each other.

Inserted into the inside of the tendon on the back of the ring
finger.

Use. To draw the ring finger inward.

The following muscle also appears on the back of the hand.

Adductor Indicis Manus,

Arises, from the os trapezium, and from the superior part and
inner side of the metacarpal bone of the thumb.

Inserted, by a short tendon, into the outer and back part of
the first bone of the fore finger.

Use. To bring the fore finger towards the thumb.

MUSCLES OF THE INFERIOR EXTREMITIES.

THESE may be divided into the muscles situated on the out-
side of the pelvis, on the thigh, on the leg, and on the foot.

The muscles on the outside of the pelvis, which are called
muscles of the thigh,

Are composed of one layer before and three layers behind.

The layer before consists of five muscles :

1. Psoas Magnus. ~) c

~ ir > See page 346, 347.

2. lliacus Internus. )

376 MUSCLES or THE os FEMORIS.

3. Pectinalis,

Arises, broad and fleshy, from the upper and anterior part of
the os pubis or pectinis, immediately above the foramen thy-
roideum.

Inserted into the anterior and upper part of the linea aspera
of the os femoris, a little belo^v the trochanter minor, by a flat
and short tendon.

Use. To bring the thigh upwards and inwards, and to give it a
degree of rotation outwards.

4. Triceps Adductor Femoris,

Under this appellation are comprehended three distinct
muscles :

a. Adductor Longus Femoris,

Arises, by a strong roundish tendon, from the upper and
anterior part of the os pubis, and from the symphysis pubis, on
the inner side of the pectinalis.

Inserted, tendinous, near the middle of the posterior part of the
linea aspera, being continued for some way down.

b. Adductor Brevis Femoris,

Arises, tendinous, from the os pubis near its joining with the
opposite os pubis, below and behind the former.

Inserted, tendinous and fleshy, into the inner and upper part
of the linea aspera, from a little below the trochanter minor, to
the beginning of the insertion of the adductor longus.

c. Adductor Magnus Femoris,

Arises, a little lower down than the former, near the symphysis
of the os pubis, tendinous and fleshy from the tuberosity of the
os ischium ; the fibres run outwards and downwards.

Inserted into almost the whole length of the linea aspera ;
into a ridge above the internal condyle of the os femoris ; and,
by a roundish long tendon, into the upper part of that condyle,

MUSCLES OF THE OS FEMORIS. 377

a little above which, the femoral artery takes a spiral turn
towards the ham, passing between this muscle and the boiy?.

Use of these three rrfuscles, or triceps. To bring the thigh
inwards and upwards, according to the different directions of
their fibres ; and, in some degree, to roll the thigh outwards.

5. Obturator Externus,

Arises, fleshy, from the lower part of the os pubis, and fore-
part of the inner crus of the ischium ; surrounds the foramen
thyroideum ; a number of its fibres, arising from the membrane
which fills up that foramen, are collected like rays towards a
centre, and pass outwards around the root of the back part of
the cervix of the os femoris.

Inserted, by a strong tendon, into the cavity at the inner and
back part of the root of the trochanter major, adhering in its
course to the capsular ligament of the thigh bone.

Use. To roll the thigh bone obliquely outwards, and to pre-
vent the capsular ligament from being pinched.

Behind are,

First layer,

Glutens Maximus,

Arises, fleshy, from the posterior part of the spine of the os
ilium, a little higher up than the joining of the ilium with the
os sacrum, from the whole external side of the os sacrum, be-
low the posterior spinous process of the os ilium ; from the
posterior sacro-ischiatic ligament, over which part of the in-
ferior edge of this muscle hangs in a folded manner, and from
the os coccygis. All the fleshy fibres run obliquely forwards,
and a little downwards, to form a thick broad muscle, which is
divided into a number of strong fasciculi. The upper part of
it covers almost the whole of the trochanter major, between
which and the tendon of this muscle there is a lar^e bursa mu-

O

cosa, and where it is inseparably joined to the broad tendon of
the tensor vagina femoris.

Inserted, by a strong, thick, and broad tendon, into the upper
and outer part of the linea aspera, which is continued from the
32*

378 MUSCLES OF THE OS FEMORIS.

troclianter major, for some way downwards, as far as the origin
of the short head of the biceps flexor cruris — and also into the
fascia femoris.

Use. To extend the thigh, by pulling it directly backwards,
and a little outwards.

Second layer,

Glutens Medius,

Arises, fleshy, from the anterior superior spinous process of
the os ilium, and from all the outer edge of the spine of the
ilium ; except its posterior part, where it arises from the dorsum
of that bone.

Inserted, by a broad tendon, into the outer and upper mar-
gin of the trochanter major.

Use. To draw the thigh bone outwards, and a little back-
wards ; to roll the thigh bone outwards, especially when it is
bended.

N. B. The anterior and upper part of this muscle is covered
by a tendinous membrane, from which a number of its fleshy
fibres arise, and which joins with the broad tendons of the
glutens rnaximus, tensor vagina femoris, and latissimus dorsi.

Third layer consists of four muscles.

1. Glutens Minimus.

Arises, fleshy, from a ridge that is continued from the superior
anterior spinous process of the os ilium, and from the middle
of the dorsum of that bone, as far back as its great niche.

Inserted, by a strong tendon, into the fore and upper part of
the trochanter major.

Use. To assist the former in pulling the thigh outwards and

backwards, and in rolling it.
i

2. Pyriformis.

Arises, within the pelvis, by three tendinous and fleshy ori-
gins, from the second, third, and fourth pieces of the os sacrum ;
from thence growing gradually narrower, it passes out of the

MUSCLES OF THE OS FEMORIS.

379

pelvis along with the posterior crural nerve, below the niche in
the posterior part of the os ilium, where it receives a few fleshy
fibres.

Inserted, by a roundish tendon, into the upper part of the
Fig. 99.* cavity, at the inner side of the

root of the trochanter major.

Use. To move the thigh a lit-
tle upwards, and roll it outwards.

3. Gemetti,

Arise, by two distinct origins ;
the superior from the spinous
process, and the inferior from
the tuberosity of the os ischium ;
also, from the posterior sacro-
ischiatic ligament. They are
both united by a tendinous fleshy
membrane, and form a purse for
the tendon of the obturator in-
ternus muscle, which was for-
merly described.
Inserted, tendinous and fleshy, into the cavity at the inner
side of the root of the trochanter major, on each side of the
tendon of the obturator internus, to which they firmly adhere.

Use. To roll the thigh outwards, and to preserve the tendon
of the obturator internus from being hurt by the hardness of
that part of the os ischium over which it passes ; also, to
hinder it from starting out of its place, while the muscle is in
action.

* The deep muscles of the gluteal region. 1. The external surface of the
ilium. 2. The posterior surface of the sacrum. 3. The posterior sacro-iliac
ligaments. 4. The tuberosity of the ischium. 5. The great or posterior sacro-
ischiatic ligament. 6. The lessor or anterior sacro-ischiatic ligament. 7. The
trochanter major. 8. The gluteus minimus. 9. The pyriformis. 10. The
gemellus superior. 11. The obturator internus muscle, passing out of the
lesser sacro-ischiatic foramen. 12. The gemellus inferior. 13. The quadratus
femoris. 14. The tipper part of the adductor magnus. lo. The vastns exfer-
nus. 16. The biceps. 17. The gracilis. 18. The semi-tendinosus.

380 MUSCLES OF THE THIGH.

4. Quadratus Femoris,

Arises, tendinous and fleshy, from the outside of the tuberosity
of the os ischium; and, running transversely, is

Inserted, fleshy, into a rough ridge, continued from the root
of the large trochanter to the root of the small one.

Use. To roll the thigh outwards.

Muscles situated on the Thigh.

These are called muscles of the leg ; and consist of one, on
the outside; two on the inside; four, before; and four, behind.

Previous to the description of the muscles that are situated
on the thigh and leg, it is necessary to take notice of a broad
tendinous fascia or sheath, (aponeurosis of the lower extremi-
ties^) which is sent off from the back and from the tendon of
the glutei and adjacent muscles.

It is a strong thick membrane on the outside of the thigh
and leg ; but, towards the inside of both, it gradually turns
thinner, and has rather the appearance of cellular substance
than a tendinous membrane. A little below the trochanter
major, it is firmly fixed to the linea aspera ; and, farther
down, to that part of the head of the tibia that is next the
fibula ; where it sends off the tendinous expansion along the
outside of the leg.

It serves to strengthen the action of the muscles, by keeping
them firm in their proper places while in action, particularly
the tendons that pass over the joints where this membrane is
thickest, and it gives origin to a number of. the fleshy fibres of
the muscles.

On the outside is,

Tensor Vagina Femoris,

Arises, by a narrow, tendinous, and fleshy beginning, from
the external part of the anterior superior spinous process of the
os ilium.

Inserted, a little below the trochanter major, into the inner
side of the membranous fascia which covers the outside of the
thigh.

MUSCLES OF THE THIGH.

381

Fig. 100.*

Use. To stretch the membranous
fascia, to assist in the adduction of
the thigh, and somewhat in its rota-
tion inwards.

On the inside are,

1 . Sartorius,

Arises, tendinous, from the anterior
superior spinous process of the os ilium,
soon grows fleshy, runs down for some
space upon the rectus, and going oblique-
ly inwards, it passes over the vastus in-
ternus, and, about the middle of the os
femoris, over part of the triceps ; it
runs down farther between the tendon
of the adductor magnus and that of the
gracilis muscles.

Inserted, by a broad and thin ten-
don, into the inner side of the tibia,
near the inferior part of its tubercle.

Use. To bend the leg obliquely in-
wards, or to bring one leg across the
other.

2. Gracilis,

Arises, by a thin tendon, from the os pubis, near the symphy-
sis of these two bones, soon grows fleshy, and, descending by
the inside of the thigh, is

Inserted, tendinous, into the tibia under the sartorius.

Use. To assist the sartorius.

Before are,

* The muscles of the anterior femoral region. 1. The crest of the ilium.
2. Its anterior superior spinous process. 3. The gluteus medius. 4. The ten-
sor vaginoe femoris ; its insertion into the fascia lata is shown inferiorly. 5,
The sartorius. 6. The rectus. 7. The vastus externus. 8. The vastus inter-
nus. 9. The patella. 10. The iliacus internus. 11. The psoas magnus.
12. The pectineus. 13. The adductor longus. 14. Part of the adductor mag-
nus. 15. The gracilis.

382 MUSCLES OF THE THIGH.

1. Rectus,

Arises, fleshy, from the inferior anterior spinous process of the
os ilium, and tendinous from the dorsum of the ilium, a little
above the acetabulum ; runs down over the anterior part of the
cervix of the os femoris ; the fibres not being straight, but
running down like the plumage of a feather obliquely outwards
and inwards, from a tendon in* the middle.

Inserted, tendinous, into the upper part of the patella, from
which a thin tendon runs down, on the forepart of this bone,
to terminate in a thick strong ligament, which is sent off from
the inferior part of the patella^ and inserted into the tubercle of
the tibia.

Use. To extend the leg, and, in a powerful manner, by the
intervention of the patella, like a pulley.

2. Vastus ExternuSj

Arises, broad, tendinous and fleshy, from the root of the
trochanter major, and upper part of the linea aspera ; its origin
being continued from near the insertion of the gluteus minimus,
the whole length of the linea aspera, by fleshy fibres which run
obliquely forwards to a middle tendon, where they terminate.

Inserted into a large share of the upper part of the patella ;
and part of it ends in an aponeurosis, which is continued down
to the leg, and in its passage is firmly fixed to the head of the
tibia.

Use. To extend the leg.

3. Vastus Interims,

Arises, tendinous and fleshy, from between the forepart of the
os femoris and root of the trochanter minor, and from almost
all the inside of the linea aspera, by fibres running obliquely
forwards and downwards.

Inserted, tendinous, into the upper and inside of the patella,
continuing fleshy lower than the vastus externus. Part of it
likewise ends in an aponeurosis continued down to the leg, and
fixed in its passage to the upper part of the tibia.

Use. To extend the leg.

MUSCLES OF THE THIGH,

383

Fig. 101.*

4. Cruralis,

Arises, fleshy, from between the two trochanters of the os
femoris, but nearer the lesser trochanter, and firmly adhering
to most of the forepart of the os femoris, and connected to both
vasti muscles.

Inserted, tendinous, into the upper
part of the patella, behind the rectus.

Use. To assist in the extension of
the leg.

N. B. These four muscles before,
being inserted into the patella, have
the same effect upon the leg as if they
were immediately inserted into it by
means of the strong tendon, or rather
ligament which is sent oft* from the
inferior part of the patella to the tibia.
Behind are,

1 . Semitendinosus,
Arises, tendinous and fleshy, in com-
mon with the long head of the biceps,
from the posterior part of the tubero-
sity of the os ischium ; and sending
down a long roundish tendon, which
ends flat, is

Inserted, into the inside of the ridge
of the tibia, a little below its tubercle.

Use. To bend the leg backwards
and a little inwards.

* The muscles of the posterior femoral and gluteal region. 1. The gluteus
medius. 2. The gluteus maximus. 3. The vastus externus covered in by
fascia lata. 4. The long head of the biceps. 5. Its short head. 6. The semi-
tendinosus. 7. The semi-membranosus. 8. The gracilis. 9. A part of the
inner border of the adductor magnus. 10. The edge of the sartorius. 11. The
popliteal space. 12. The gastrocnemius muscle: its two heads. The tendon
of the biceps forms the outer hamstring ; and the sartorius with the tendons of
the gracilis, semi-tendinosus, and semi-membranosus, the inner hamstring

•384 MUSCLES OF THE THIGH.

2. Semimembranosus,

Arises, tendinous, from the upper and posterior part of the
tuberosity of the os ischium ; sends down a broad flat tendon,
which ends in a fleshy belly, and, in its descent, runs at first
on the forepart of the biceps, and lower, between it and the

semitendinosus.

•

Inserted, tendinous, into the inner and back part of the head
of the tibia.

Use. To bend the leg, and bring it directly backward.

N. B. The two last form what is called the inner hamstring.

3. Biceps Flexor Cruris,

Arises by two distinct heads. The first, called longus, arises,
in common with the semitendinosus, from the upper and pos-
terior part of the tuberosity of the os ischium. The second,
called brevis, arises from the linea aspera, a little below the
termination of the gluteus maxirnus, by a fleshy acute begin-
ning, which soon grows broader as it descends to join with the
first head, a little above the external condyle of the os femoris.

Inserted, by a strong tendon, into the upper part of the head
of the fibula.

Use. To bend the leg.

JV. B. This muscle forms what is called the outer ham-
string; and between it and the inner, the nervus popliteus,
the arteria and vena poplitea, are situated.

4. Popliteus,

Arises, by a round tendon, from the lower and back part of
the external condyle of the os femoris, then runs over the liga-
ment that involves the joint; firmly adhering to it, and part of
the semilunar cartilage. As it runs over the joint, it becomes
fleshy, and the fibres run obliquely inwards, being covered
with a thin tendinous membrane.

Inserted, broad, thin and fleshy, into a ridge at the upper
and internal edge of the tibia, a little below its head.

Use. To assist in bending the leg, and to prevent the cap-

x I

MUSCLES ON THE FRONT OF THE LEG. 385

sular ligament from being pinched. After the leg is bent, this
muscle serves to roll it inwards.

Muscles situated on the Leg.

These muscles may be arranged in the two general classes of flexors and ex-
tensors of the foot, and flexors and extensors of the toes ; but several of them,
viz. the tibialis and the peronei, produce effects which are different from
flexion or extension. For the accommodation of the student of anatomy, they
may be studied in the order of their position as they lie on the front, on the
outside, and on the back of the leg.

Muscles on the Front of the Leg.

1. Tibialis Anticus.

Arises, tendinous and fleshy, from the middle of that process
of the tibia, to which the fibula is connected above ; then it
runs down fleshy on the outside of the tibia ; from which, and
the upper part of the interosseous ligament, it receives a num-
ber of distinct fleshy fibres ; near the extremity of the tibia, it
sends off a strong round tendon, which passes under part of the
ligamentum tarsi annulare near the malleolus internus.

Inserted, tendinous, into the inside of the os cuneiforme
internum, and posterior end of the metatarsal bone that sustains
the great toe.

Use. To bend the foot, by drawing it upwards, and, at the
same time, to turn the toes inwards.

2. Extensor Proprius Pollicis Pedis,

Arises, by an acute, tendinous, and fleshy beginning, some
way below the head and anterior part of the fibula, along
which it runs to near its lower extremity, connected to it by a
number of fleshy fibres, which descend obliquely towards a
tendon.

Inserted, tendinous, into the posterior part of the first and last
joint of the great toe.

Use. To extend the great toe.
33

386

MUSCLES ON THE FRONT OF THE LEG.

3. Extensor Longus Digitorum Pedis,

Arises, tendinous and fleshy, from the upper and outer part
of the head of the tibia, and from the head of the fibula where
Fig. 102.* it joins with the tibia, and from the

interosseous ligament; also from the
tendinous fascia, which covers the up-
per and outside of the leg by a number
of fleshy fibres ; and tendinous and
fleshy from the anterior spine of the
fibula, almost its whole length, where it
is inseparable from the peroneus tertius.
It splits into four round tendons, under
the ligamentum tarsi annulare.

Inserted, by a flat tendon, into the
root of the first joint of each of the four
small toes ; and is expanded over the
upper side of the toes, as far as the root
of the last joint.

Use. To extend all the joints of the
four small toes.

N. B. A portion of this muscle,
which is called

4. Peroneus Tertius,

Arises, from the middle of the fibula,
continues down to near its inferior ex-
tremity, and sends its fleshy fibres forwards to a tendon, which
passes under the annular ligament, and is

* The muscles of the anterior tibial region. 1. The extensor muscles inserted
into the patella. 2. The subcutaneous surface of the tibia. 3. The tibialis
anticus. 4. The extensor communis digitorum. 5. The extensor proprius
pollicis. 6. The peroneus tertius. 7. The peroneus longus. 8. The peroneus
brevis. 9, 9. The borders of the soleus muscle. 10. A part of the inner belly
of the gastrocnemius. 11. The extensor brevis digitorura ; the tendon in front
of this number is that of the peroneus tertius ; and that behind it, the tendon
of the peroneus brevis.

MUSCLES ON THE LEG. 387

Inserted, into the root of the metatarsal bone that sustains the
little toe.

Use. To assist in bending the foot.

Muscles on the outside of the Leg.

1. Peroneus Longus.

Arises, tendinous and fleshy, from the forepart of the head of
the peroneus, or fibula, the fibres running straight down ; also
from the upper and external part of the fibula, where it begins
to rise into a round edge ; as, also, from the hollow between that
and its anterior edge, as far down as to reach within a hand's
breadth of the ankle, by a number of fleshy fibres, which run
outwards towards a tendon, that subsequently becomes long and
round, and passes through a channel at the outer ankle, in the
back part of the inferior extremity of the fibula ; then being
reflected to the sinuosity of the os calcis, it runs along a
groove in the os cuboides, above the muscles in the sole of the^
foot.

Inserted, tendinous, into the outside of the root of the meta-
tarsal bone that sustains the great toe, and by°some tendinous
fibres into the os cuneiforme internum.

Use. To turn the foot outwards, and to extend it a little.

2. Peroneus Brevis,

Arises, by an acute fleshy beginning, from above the middle
of the external part of the fibula ; from the outer side of the
anterior spine of this bone ; as also from its round edge externally,
the fibres running obliquely outwards towards a tendon on its
external side : it sends off a round tendon which passes through
the groove at the outer ankle, being there included under the ,
same ligament with that of the preceding muscle ; and a little
farther, it runs through a particular one of its own.

Inserted, tendinous, into the root and external part of the
metatarsal bone that sustains the little toe.

Use. To assist the former in pulling the foot outwards, and
extending it a little.

MUSCLES ON THE LEG.

Muscles on the Back of the Leg.
1. Gastrocnemius Externus, seu Gemellus,

Arises, by two distinct heads. The first head arises from the
Fig. 103.* upper and back part of the internal condyle
of the os femoris, and from that bone, a little
above its condyle, by two distinct tendinous
origins. The second head arises tendinous
from the upper and back part of the exter-
nal condyle of the os femoris. A little be-
low the joint, their fleshy bellies unite in a
middle tendon ; and, below the middle of
the tibia, it sends off a broad thin tendon,
which joins a little above the extremity of
the tibia with the tendon of the following.

2. Soleus, seu Gastrocnemius Internus,
Arises by two origins. The first is from
the upper and back part of the head of the
fibula, continuing to receive many of its
fleshy fibres from the posterior part of that
bone for some space below its head. The
other origin begins from the posterior and
upper part of the middle of the tibia ; and
runs inwards along the inferior edge of the
popliteus towards the inner part of the tibia,
from which it receives fleshy fibres for some
way down. The flesh of this muscle,
covered by the tendon of the gemellus, runs down nearly as far
as the extremity of the tibia ; a little above which the tendons of

* The superficial muscles on the posterior surface of the leg. 1. Biceps
flexor cruris muscle, forming the outer hamstring. 2. The tendons forming
the inner hamstring, consisting of the tendons of the semitendinosus, semi-
membranosus, gracilis and sartorius. 3. The popliteal space. 4. The gastroc-
nemius muscle. 5, 5. The soleus muscle. 6. Tendo Achillis. 7. The posterior
tuberosity of the os calcis. 8. The tendons of the peroneus longus and brevis
muscles, passing behind the outer ankle. 9. The tendons of the deep layer of
muscles passing into the foot behind the inner ankle.

MUSCLES ON THE LEG.

389

both gastrocnemii unite, and form a strong round cord, which
is called tendo-Achillis.

Inserted into the upper and posterior part of the os caleis, by
Fig. 104.* the projection of which the tendo-Achillis is
placed at a considerable distance from the
tibia.

Use. To extend the foot, by bringing it
backwards and downwards.

3. Plantaris.

Arises, thin and fleshy, from the upper
and back part of the root of the external
condyle of the os femoris, near the interior
extremity of that bone, adhering to the liga-
. ment that involves the joint in its descent.
It passes along the second origin of the
soleus and under the gemellus, where it
sends off a long, slender, thin tendon, which
comes from between the great extensors,
where they join tendons ; then runs down
by the inside of the tendo-Achillis.

Inserted, into the inside of the posterior
part of the os caleis, below the tendo-
Achillis.

Use. To assist the former, and to pull the
capsular ligament of the knee from between
the bones. It seems likewise to assist in rolling the foot
forwards,

* The deep layer of muscles of the posterior libial region. 1. The lower
extremity of the femur. 2. The ligamentum posticum Winslowii. 3. The
tendon of the semi-membranosus muscle dividing into its three slips. 4. The
internal lateral ligament of the knee-joint. 5. The external lateral ligament.
0. The popliteus muscle. 7. The flexor longus digitorum. 8. The tibialis
posticus. 9. The flexor longus pollicis. 10. The peroneus longus muscle.
11. The peroneus brevis. 12. The tendo-Achillis divided at its insertion into
the os caleis. 13. The tendons of the tibialis posticus and flexor longus digito-
rum muscles, just as they are about to pass beneath the internal annular liga-
ment of the ankle ; the interval between the latter tendon and the tendon of
the flexor longus pollicis is occupied by the posterior tibial vessels and nerves.

33*

390 MUSCLES ON THE LEG.

4. Flexor Longus Digitorum Pcdis, Profundus, Perforans,

Arises, by an acute tendon, which soon becomes fleshy from
the back part of the tibia, some way below its head, near the
entry of the medullary artery ; which beginning, is continued
down the inner edge of this bone by short fleshy fibres, ending
in its tendon ; also by tendinous and fleshy fibres, from the outer
edge of the tibia, and between this double order of fibres, the
tibialis posticus muscle lies enclosed. Having passed under two
annular ligaments, it then passes through a sinuosity at the
inside of the os calcis ; and about the middle of the sole of the
foot, divides into four tendons, which passes through the slit?
of the perforatus ; and just before its division it receives a con-
siderable tendon from that of the flexor pollicis longus.

Inserted into the extremity of the last joint of the four lesser
toes.

Use. To bend the last joint of the toes.

5. Tibialis Posticus,

Arises, by a narrow fleshy beginning, from the fore and upper-
part of the tibia, just under the process which joins it to the
fibula ; then passing through a perforation in the upper part of
the interosseous ligament, it continues its origin from the back
part of the fibula next the tibia, and from near one half of the
upper part of the last named bone ; as also, from the interos-
seous ligament, the fibres running towards a middle tendon,
which sends off a round one that passes in a groove behind
the malleolus internus.

Inserted, tendinous, into the upper and inner part of the os
naviculare, being farther continued to the os cuneiforme inter-
num and medium ; besides it gives some tendinous filaments to
the os calcis, os cuboides, and to the root of the metatarsal bone
that sustains the middle toe.

Use. To extend the foot, and to turn the toes inwards.

6. Flexor Longus Pollicis Pedis,

Arises, by an acute, tendinous, and fleshy beginning, from
the posterior part of the fibula, some way below its head, being

MUSCLES ON THE SOLE OF THE FOOT. 391

continued down the same bone, almost to its inferior extremity,
by a double order of oblique fleshy fibres ; its tendon passes
under an annular ligament at the inner ankle.

Inserted, into the last joint of the great toe, and, generally,
sends a small tendon to the os calcis.

Use. To bend the last joint of this toe.

On the upper surface of the foot there is one muscle, viz.

Extensor Brevis Digitorum Pedis,

Arises, fleshy and tendinous, from the fore and upper part of
the os calcis ; and soon forms a fleshy belly, divisible into four
portions, which send off an equal number of tendons that pass
over the upper part of the foot, under the tendons of the for-
mer.

Inserted, by four slender tendons, into the tendinous expan-
sion from the extensor longus which covers the small toes, ex-
cept the little one ; also into the tendinous expansion from the
extensor pollicis, that covers the upper part of the great toe.

Use. To extend the toes.

Muscles on the Sole of the Foot.

On the sole of the foot there is a strong tendinous membrane called Aponturosis
Plantaris, which originates from the tuberosity of the os calcis, and proceeds
forward to the toes, increasing gradually in breadth.

It is divided into three portions. That in the middle is the largest ; it protects
and covers the short flexor muscles, and the tendons in the middle of the foot.
That on the outside, which covers the adductor and flexor of the little toe, it>
next in size. The internal portion, which covers the adductor of the great
toe, is the smallest.

The edges of these portions dip down so as to separate the muscles they cover
from each other. They are divided into five processes, corresponding with
the heads of the metatarsal bones ; each of these portions is divided into two
bands, which are inserted into each side of the head of each metatarsal bone,
and the tendons, nerves, and arteries pass between them.

Immediately under the middle portion of this aponeurosis are the common short
flexors of the toes, viz.

1. Flexor Brevis Digitorum Pedis Sublimis Perforatus,

Arises, by a narrow fleshy beginning, from the inferior and
posterior part of the protuberance of the os calcis, between
the adductors of the great and little toes, soon forms a thick

392

MUSCLES ON THE SOLE OF THE FOOT.

Fig. 105.*

fleshy belly, which sends off four tendons that split for the pas-
sage of the flexor longus.

Inserted into the second phalanx of
the four lesser toes. The tendon of the
little toe is often wanting.

Use. To bend the second joint of the
toes,

2. Flexor Digitorum Accessorim, seu,
Massa Carnea Jacobii Sylvii,

Arises, by a thin fleshy origin, from
most part of the sinuosity at the in-
side of the os calcis, which is continued
forwards, for some space on the same
bone ; also, by a thin tendinous begin-
ning, from before the tnberosity of the
os calcis, externally, and, soon becom-
ing all fleshy, is

Inserted into the tendon of the
flexor longus, just at its division into
four tendons.
Use. To assist the flexor longus.

3. Lumbricales Pcdis,

Arises, by four tendinous and fleshy beginnings, from the
tendon of the flexor profundus, just before its division, near
the insertion of the massa carnea.

Inserted, by four slender tendons, into the inside of the first
joint of the four lesser toes, and are lost in the tendinous ex-
pansion that is sent from the extensors to cover the upper part
of the toes.

* The first layer of muscles in the sole of the foot : this layer is exposed by
the removal of the plantar fascia. 1. The os calcis. 2. The posterior part of
the plantar fascia divided transversely. 3. The abductor pollicis. 4. The ab-
ductor minimi digiti. 5. The flexor brevis digitorum. 6. The tendon of the
flexor longus pollicis muscle. 7, 7. The lumbricales. On the second and third
toes, the tendons of the flexor longus digitorum are seen passing through the
bifurcation of the tendons of the flexor brevis digitorum.

MUSCLES ON THE SOLE OF THE FOOT. 393

Use. To increase the flexion of the toes, and to draw them
inwards.

On the inside of the foot, and under the common flexors, are
the muscles which are considered as exclusively appropriated
to the great toe, viz.

1. Abductor Pollicis

Arises, from the internal side of the tuberosity of the os
calcis, and from a ligament which extends from this tuberosity
to the sheath of the tendon of the tibialis posticus muscle, and
also from the internal and inferior side of the os navicu-
lare and cuneiforme internurn. It likewise arises from that
portion of the aponeurosis plantaris, which separates it from
the short flexor of the toes, and many of its fibres appear to be
connected with the ligaments which pass from the posterior to
the anterior bones of the foot : as it passes under the cuneiform
bone, a portion of its lower surface is tendinous.

It is inseparably connected to the flexor of the great toe, and
is inserted into the internal sesamoid •• bone, and the inferior
and internal part of the root of the first bones of the great toe.

This muscle not only separates the great toe from the other
toes, but it must increase the curvature, or arched form of the
foot.

2. Flexor Brevis Pollicis Pedis, «

Arises , tendinous, from the under and forepart of the os
calcis, where it joins with the os cuboides, from the os cunei-
forme externum, and is inseparably united with the abductor
and adductor pollicis.

Inserted, into the internal and external sesamoid bones, along
with the abductor and adductor pollicis, and into the root of
the first joint of the great toe.

Use. To bend the first joint.

3. Adductor Pollicis Pedis,

Arises, by a long thin tendon, from the os calcis, from the
os cuboides, from the os cuneiforme externum, and from the
root of the metatarsal bone of the second toe.

394

MUSCLES ON THE SOLE OF THE FOOT.

Fig. 106.* Inserted into the external os sesa-

moideum, and root of the inetatarsal
bone of the great toe.

Use. To bring this toe nearer the
rest.

Near the outer edge of the foot,
under the second portion of the aponeu-
rosis plantaris, are the muscles pecu-
liar to the little toe, viz.

1. Adductor Minimi Digiti Pedis.

Arises, tendinous and fleshy, from
the semicircular edge of a cavity on
the inferior part of the protuberance of
the os calcis, and from the root of the
metatarsal bone of the little toe.

Inserted into the root of the first
joint of the little toe externally.
Use. To draw the liyle toe outwards from the rest, and assist
in preserving the arched form of the foot.

2. Flexor Brevis Minimi Digiti Pedis,

Arises, tendinous, from the os cuboides, near the sulcus
or furrow for lodging the tendon of the peroneus longus ;
fleshy from the outside of the metatarsal bone that sustains the
little toe, below its protuberant part.

Inserted, into the anterior extremity of the metatarsal bone,
and root of the first joint of this toe.

Use. To bend this toe.

* The third and a part of the second layer of muscles of the sole of the foot. 1.
The divided edge of the plantar fascia. 2. The musculus accessorius. 3. The
tendon of the flexor longus digitorum, previously to its division. 4. The ten-
don of the flexor longus pollicis. 5. The flexor brevis pollicis. 6. The ad-
ductor pollicis. 7. The flexor brevis minimi digiti. 8. The transversus pedis.
9. Interossei muscles, plantar and dorsal. 10. A convex ridge formed by the
tendon of the peroneus longus muscle in its oblique course across the foot.

INTEROSSEOUS MUSCLES. 395

Between the metatarsal bones are four external and three internal interossei :
and one muscle which is common to all the metatarsal bones.

Interossei Pedis Externi, Bicipites.

1. Abductor Indicis Pedis ,

Arises, tendinous and fleshy, by two origins, from the root
of the inside of the metatarsal bone of the fore toe, from the
outside of the root of the metatarsal bone of the great toe, and
from the os cuneiforme internum.

Inserted, tendinous, into the inside of the root of the first
joint of the fore toe.

Use. To pull the fore toe inwards from the rest of the small
toes.

2. Adductor Indicis Pedis,

Arises, tendinous and fleshy, from the roots of the metatarsal
bones of the fore and second toe.

Inserted, tendinous, into the outside of the root of the first
joint of the fore toe.

Use. To pull the fore toe outwards towards the rest.

3. Adductor Medii Digiti Pedis,

Arises, tendinous and fleshy, from the roots of the metatarsal
bones of the second and third toes.

Inserted, tendinous, into the outside of the root of the first
joint of the second toe.

Use. To pull the second toe outwards.

4. Adductor Tertii Digiti Pedis,

Arises, tendinous and fleshy, from the roots of the metatarsal
bones of the third and little toe.

Inserted, tendinous, into the outside of the root of the first
joint of the third toe.

Use. To pull the third toe outwards.

396 INTEROSSEOUS MUSCLES.

Interossei Pedis Interni,

1. Abductor Medii Digiti Pedis,

Arises, tendinous and fleshy, from the inside of the root of
the metatarsal bone of the middle toe internally.

Inserted, tendinous, into the inside of the root of the first
joint of the middle toe.

Use. To pull the middle toe inwards.

2. Abductor Tertii Digiti Pedis,

Arises, tendinous and fleshy, from the inside and inferior
part of the root of the metatarsal bone of the third toe.

Inserted, tendinous, into the inside of the root of the first
joint of the third toe.

Usl. To pull the third toe inwards.

3. Abductor Minimi Digiti Pedis,

Arises, tendinous and fleshy, from the inside of the root of
the metatarsal bone of the little toe.

Inserted, tendinous, into the inside of the root of the first
joint of the little toe.

Use. To pull the little toe inwards.

The common muscle,

Transversalis Pedis,

Arises, tendinous, from the under part of the anterior
extremity of the metatarsal bone of the great toe, and from the
internal os sesamoideum of the first joint, adhering to the
adductor pollicis.

Inserted, tendinous, into the under and outer part of the
anterior extremity of the metatarsal bone of the little toe, and
ligament of the next toe.

Use, to contract the foot, by bringing the great toe and the
two outermost toes nearer each other.

MOTIONS OF THE SKELETON. 397

CHAPTER IX.

OBSERVATIONS ON THE MOTIONS OF THE SKELETON.

THE falling down of the body during life, when muscular
action is suspended, as well as the examination of the artificial
skeleton, evince that this machine is not constructed to preserve
the erect position of itself; but that, when unsupported, it bends
at the joints, and invariably falls forward.

It is retained in the erect position by the action of muscles :
and that the muscles should produce this effect, it is necessary
that they should have a fixed basis to act from.

This basis is the feet, and they are fixed to the ground by
the weight of the body.

To keep the body from falling, it is necessary that the centre
of gravity should be immediately over the centre of the common
basis.

All our movements, both in walking, standing, and rising
from our seats, are regulated by this principle ; and whenever
we move our body, so that the centre of gravity is changed,
we must change the position of the feet, that the centre of the
basis may be directly under it.

If this proposition were not almost self-evident, it might be
illustrated by several very easy experiments.

If a person stand against a wall with his heels and the back
parts of his legs and thighs in contact with it, and, in this situa-
tion, attempts to stoop forward, he will fall upon his face ; there
is no power in his muscles, or in any other part of the body,
when thus circumstanced, to prevent it ; but a small movement
forward of one foot, will enable him to stoop with ease by
altering the basis of the body.

When we sit in such a position that we cannot bring the
centre of gravity over the feet, the lower limbs are divested of
34

398 ADJUSTMENT OF THE CENTRE OF GRAVITY.

all power of elevating the body : this is always the case when
we sit with the thighs and legs at right angles with each other.
Bend the knees to an acute angle, so that the feet are placed
under the body, and we rise with ease.

When we wish to stoop forward without advancing one of
our feet, we acquire the power in a small degree, by placing
our hands behind us, to preserve the equilibrium.

Some old persons, whose spines curve forwards in conse-
quence of age, bend their lower limbs, so that the pelvis may
be projected backwards beyond the centre of the base of the
body, and form a counterpoise to the upper part of the trunk.

Bending the knees alone, without projecting the pelvis back-
wards, will not produce this effect ; for a person who stands
with his back to a wall will bend his knees without obtaining
this advantage, while the heels and back part of the pelvis are
in contact with the wall.

When we stand with the toes pointing directly forwards, the
base of the body is a square ; of which the feet are two of the
sides. As the positions of the feet are changed, the figure of
the base and its centre necessarily change also. When the feet
are placed one immediately before the other, the centre is be-
tween the toes of the one and the heel of the other. When
the position of the feet is such, that the toes point directly out-
wards, and the heels are opposite to each other, the centre of
the base is between the heels.

In these cases, when the situation of .the centre of the base is
changed, we immediately change the centre of gravity. Thus,
as we turn the toes outwards, the centre of the base moves
backwards, we, therefore, immediately make the body more
erect ; and by that means keep the centre of gravity over the
centre of the base.

We move the centre of gravity laterally, as well as back-
wards and forwards, in conformity to this principle.

Thus, when we raise one foot from the ground, the body
inclines so much in the opposite direction, that the centre of
gravity is directly over the other. If the spine is diseased in
one spot, and assumes a lateral curvature, placing the centre of

ADJUSTMENT OF THE CENTRE OF GRAVITY. 399

gravity on one side of the natural centre of the base ; another
curve is formed by a muscular action, in a sound part of the
spine, to counteract the first, and keep the centre of gravity in
its natural position.

The perception of a tendency to fall, when the centre of grav-
ity is in a wrong situation, first induces us to make efforts to
resist this tendency ; we learn by experience what these efforts
ought to be : and by habit we at length make them without
consciousness.

As the natural tendency of the skeleton, when we stand, is
to bend at the articulations, and, therefore, to fall forwards; the
muscles which have the principal effort in keeping the body
erect, must be the extensors.

Thus, the muscles on the back of the leg, and particularly
the soleus, keep the tibia erect : while the muscles on the front
of the thigh, the vasti and crureus, produce the same effect
upon the os femoris : the bones being kept steady by the occa-
sional counteraction of the antagonist muscles.

The whole lower limb is thus made erect by an exertion
which begins at the foot, while the foot is fixed to the ground
by the weight and pressure of the body above it.

The trunk of the body has a strong tendency to bend for-
ward at the articulations of the thigh bones and the ossa
innominata. This tendency is resisted by the muscles which
lie on the back part of the ossa femoris, and extend the trunk
on those bones, viz. the glutei maximi.

The muscles which arise from the tuberosity of the ischium,
and are inserted into the leg, the semitendinosus, semimembra-
nosus, and the long head of the biceps flexor cruris, have also
this effect.

The flexure of the thoracic and lumbar portions of the spine
is counteracted by the sacro-lumbalis, and longissimus dorsi,
which act from the sacrum and back parts of the pelvis. The
yellow ligaments, which are elastic, must also co-operate to
this effect : so that with regard to the spine, there is an additional
agent distinct from the muscular power.

Indeed, respecting the vertebral articulations in general, it

400 MUSCLES WHICH KEEP THE BODY ERECT.

may be observed, that the connexion of the bodies of the
vertebrae, by the intervertebral cartilaginous matter, and of the
plates behind, by the elastic ligament, renders these articulations
perfectly anomalous ; and very different in their principles from
the articulations in general.

In no part of the skeleton is this tendency to bend forward
more strongly perceived thac in the head. When we are
awake, and the muscles in a healthy situation, it is effectually
restrained, and the head kept erect, by the splenius and corn-
plexus, and other muscles, which act from the spine below,
upon the back part of the head and the vertebrae of the neck.

When we stand on one foot, some very different muscles are
called into action ; the tendency of the body is to fall sideways,
towards the foot which is raised from the ground. To coun-
teract this tendency the two larger peronei muscles, which are
situated on the outside of the leg, act from the foot, to keep the
leg erect. The vastus externus acts upon the same principle
from the leg upon the os femoris. The gluteus medius and
minimus, and the muscle of the fascia, act from the os femoris
upon the pelvis and trunk ; while the quadratus lumborum,
and those abdominal muscles which draw the spine to that side,
continue the operation : and so do likewise the muscles which
act on the same side of the neck and head.

In rising from a seat, the tibialis anticus acts very powerfully,
to keep the tibia erect, and prevent it from inclining backwards.
The two vasti, and the cruraeus, raise up the os femoris, while
the gluteus maximus, the sernitendinosus, and semimembra-
nosus, and the long head of the biceps, extend the trunk of the
body.

There are several modes of walking, which are different from
each other, in a small degree.

We may walk, for example, with the knee of the hind limb
straight or bent, as we bring it forward. This circumstance is
merely a matter of accommodation. But there are two essential
processes in walking, viz. 1. Projecting one foot forward, and
placing it on the ground while thus projected : and 2. Moving
the body over that foot.

MUSCLES EMPLOYED IN RISING FROM A SEAT. 401

The mode of projecting the foot requires no explanation;
but the manner of bringing it to the ground, when thus ad-
vanced ought to be noticed.

If, after standing with both feet on the same line, we move
one foot forwards, suppose the right foot, it cannot be applied
flat to the ground, unless we either incline the body forward or
move the pelvis on the left thigh, so that the right side may
present obliquely forward ; or lower the right side of the pelvis,
so that it may be nearer the ground.

When we incline the body forward, and thus bring the right
foot to the ground, we perform the second essential process in
walking, along with the first : for we move the body over the
fore foot. The muscles on the front part of the hind leg, and
particularly the tibialis anticus, seem to produce this effect, by
bending, or inclining forward, the tibia on the foot.

When the foot is brought to the ground by a rotation of the
pelvis, it is likewise the tibialis anticus, and the muscles on the
front of the hind leg, that move the body over it, or that begin
the motion.

The gastrocnemius and soleus, and the flexors of the toes,
particularly that of the great toe, occasionally co-operate with
great effect. By raising the heel, and thus lengthening the
hind limb, they push the body forward, and continue its
motion in that direction after the effect of the tibialis anticus
ceases. The length of the step appears, therefore, to require
this elevation of the heel, and depression of the toes ; but it
should be observed, that when we take long steps, we also turn
the pelvis partly round, presenting the side obliquely forward ;
and in this manner increase the anterior projection of the front leg.

Although the action of the gastrocnemius, &c., seems neces-
sary to walking with long steps, we can walk without their
operation. This is proved incontestably by the act of walking
on the heel : when the gastrocnemii and the flexors are so far
from acting, that they are in a state of extension. In this ope-
ration, the principal effort seems to be made by the tibialis
anticus, and the muscles on the front of the leg ; and the exten-
sor muscles on the front of the thigh.
34*

402 MOTIONS NECESSARY IN WALKING.

Notwithstanding these facts, the action of the gastrocnemius
and soleus is essential whenever we raise the heel from the
ground, while the weight of the body presses on the front part
of the foot ; and it then acts with a force which equals, if it
does not exceed, the weight of the body.

Jumping, at the first view of it, appears an extraordinary
operation ; but if a man wh<? lies on the ground, with his feet
against a wall, makes a muscular exertion, such as is necessary
for jumping, the nature of the operation is very intelligible. It
is a sudden extension of the feet and knees, and sometimes of
the trunk of the body. The stroke is made against the wall ;
but as that does not yield, the whole motion is impressed upon
the body ; which is projected from the wall horizontally in the
same way that in jumping, it is projected from the ground
vertically.

PART IV.

OF THE GENERAL INTEGUMENTS, OR OF THE CELLULAR
MEMBRANE, AND THE SKIN.*

CHAPTER X.

OF THE CELLULAR MEMBRANE.

THAT substance which is situated between the skin and the
muscles, which is insinuated between the different muscles,
and between the fibres which compose them ; which also con-
nects the different parts of the body to each other, is denomi-
nated the Cellular Membrane, or Tela Cellulosa.

As it extends over the whole of the body, and is most inti-
mately connected with the skin, it is considered as one of the
integuments, although it is found in great quantities in some
of the internal parts.

* The integuments of the body consist of the skin or dermoid tissue, and of
that portion of the common cellular tissue which is subcutaneous and connects
the skin to the subjacent parts. The cellular tissue is loose and elastic, and by
its means the skin is loosely connected to the muscles, and not forced to follow
the muscles rigidly in their contractions. In this way the roundness of the sur-
face and the smoothness of the skin, is in a great measure preserved. The skin
is directly continuous in the mouth, nares, urethra, vagina, anus, and external
auditory meatus, with the mucous membranes lining the interior of all the
cavities of the body. The continuation or conversion of one into the other at
these orifices, is so gradual as to be almost insensible, as will be more carefully
shown under the head of mucous membrane. For this reason, by many of
the French anatomists, the skin is called the external tegumentary membrane, and
the mucous membrane the internal tegumentary membrane. The basis or derma
of the two tissues being considered with some modification the same, the cuticle
analogous to the undried mucous of the latter membrane, the papilli and seba-
ceous glands of the skin, to the villi and follicles of the mucous tissue.

This division into two membranes is not new ; it may be traced to the time
of Galen, but we are indebted for its re -introduction to science, principally to
Bonn, and Bichat. The physiological and morbid sympathies of the two mem-
branes have been long known, as being more intimate, than that which exists
between any two thoroughly distinct tissues in the human body. — P.

404 THE CELLULAR MEMBRANE.

It appears to be composed of membranous laminae, exqui-
sitely fine and delicate in their structure, which are so con-
nected to each other that they compose cells or cavities of
various forms and sizes.

When these cavities are empty, this arrangement of the cel-
lular membrane is not apparent ; but when they are distended
by water or air it is very evident.

The laminae which pass from one contiguous part to another
are of different lengths, according to the motions performed by
the different parts ; thus, about the muscles and their tendons
they are of considerable length, and between the coats of the
eye they are very short.

In some places, these laminae are compressed together, and
form a dense membrane somewhat resembling tendon ; but
whenever they are separated from each other, they appear
pellucid, and extremely delicate.

The term cell and cellgerm being used by the latest writers
on anatomy in a very definite and restricted sense, the name
cellular tissue seems to be almost improper for a structure which
is ultimately composed of filaments, intricately interwoven, but
forming open spaces, and perfectly permeable as shown by the
easy transgress of fluids from one part of the body to another.
By cell is meant, a closed vesicle, containing a nucleus, whose
walls and contents may undergo various changes by the pro-
cesses of endosmosis and exosmosis, or which may remain as a
cell in the constitution of different tissues. These cells are the
primary offspring of the cellgerm, or cytoblast (a nucleus includ-
ing a nucleolus) being analogous to the blood globules or corpus-
cles which possess the faculty of producing their like, out of the
surrounding amorphous fluid or cytoblastema ; the vital fluids
containing the elements of all organic formation. Out of such a
cell-mass, all the organs in the embryo are developed, and we
may still observe similar transformations, in the processes of repro-
duction of the different organs. Cells, as such, compose the
simpler extra-vascular tissues, as the adipose and pigmentary
cells, the horny tissue with its various modifications in the epi-
dermis, hair, nails, horns, claws, hoofs, and the epithelium. In

THE CELLULAR MEMBRANE. 405

cartilage and bone a cellular structure also is visible as has been
shown already. By their transformation into solid or hollow
fibres, lamellae and membranes, these cells become the foijnda-
tion of all the other tissues. When cells pass into fibres, they
first become elongated, and generally in both directions ; their
walls, probably strengthened by the cytoblastema adhering
around them, become contiguous, stretch themselves farther,
and thus form connecting fibres between the several nuclei ;
these after having become granular, are resolved and disappear
altogether, and by interlacings the fibrous structure is achieved.
Out of such cellular fibres, the cellular tissue is composed ; they
are extremely fine and transparent, soft but tough, and appear
somewhat contractile, particularly in the subcutaneous cellular
tissue, which contain besides the serous fluid and fat belonging
to it, numerous vessels and nerves, and may be called a main
laboratory of the animal chemistry. The investing and uniting
cellular tissue is somewhat firmer ; this covers the surface of most
single organs and their constituent parts. Cellular substance
enters also into the composition of the parenchyma of the
organs, whose constituent parts it at the same time unites and
isolates.

—As the cellular tissue serves as the connecting medium of
other tissues, it might very properly be called the connecting
tissue. In the fetus, when all the parts are soft, and as yet
unformed, it presents the aspect of mucus, filling up the inter-
stices of the other nascent organs. Hence Bordeu and Meckel,
have denominated it the mucous tissue, and supposed that its
cellular and membranous structure, was produced mechanically
by the traction of surrounding air, or the infiltration of fluid.
The term mucous, however, is inappropriate and confusing,
and applicable only to the embryonic state of the organ ; it has
been proved by microscopical investigations to be erroneous
when the development of the tissue is complete.
— The ultimate elements of all cellular tissue are fibres, not
merely globules or lamellae. These primary fibres are among
the most minute constituent elements of the human body.
Their diameter, according to the microscopical measurements

406 THE CELLULAR MEMBRANE.

of Jordon, is the ^th part of an English line. They are
transparent, and yield gelatine on boiling, in which respect
they correspond with the primitive fibres of tendons. Trevira-
nus has recently asserted from microscopical observations, that
they are hollow cylinders, which terminate by one extremity
in the minute lymphatic vessels.* This, which possibly may
be the case, and is supportec^ in some measure the opinions of
Fohman and Schwann, wants confirmation from other observers.!
— These fibres of the cellular tissue, are united so as to form
lamellated membranes which cross each other in all directions,
and produce an irregular interlacement, constituting a series of
cells, which communicate together. The tissue thus formed,
might with propriety be called arealor or filamentous. It is
of a greyish aspect and highly elastic. This latter property
does not appear to depend upon any innate elasticity in the
ultimate filaments, but on the • sinuous disposition of these
filaments, and of the fasciculi into which they are collected. It
is continuous over the whole body ; hence the great extent to
which it may be affected by diffuse inflammation.
— In many parts of the body, as in the axilla, under the sub-
scapularis muscle, and between the free surfaces of muscles and
their sheaths the cellular tissue is very loose and extensible.
— In other situations it is much more condensed and firm, as
in the submucous, subserous, and subcutaneous cellular tissues.
— In the latter of these, especially in that part constituting the
superficial fascia, and also in the cutis itself, it approaches to the
fibrous tissues, both in density, and in the mode of arrangement
of its elementary filaments, and is therefore not unfrequently
named fibro-cellular tissue. —

These laminae, when in a healthy state, appear to have no
sensibility ; but so many nerves pass through them, that pain
is generally felt when incisions are made in the cellular mem-
brane.

No vessels can be seen in their composition when they are

* Mailer's Archives for 1834, p. 410.

f Vide Breschet, sur le Systeme Lymphatique, etc. Paris, 1836.

THE CELLULAR MEMBRANE. 407

free from disease, although many pass through them. On this
account they have been considered by some very respectable
physiologists as inorganic ; but there are good reasons fdf re-
garding this sentiment as erroneous.

If a portion of cellular membrane, in the living subject, be
brought into view by a surgical operation or a wound, and be
allowed to remain some time covered by an emolient cataplasm,
or a soft plaster, a complete change of color will gradually
take place ; it will become uniformly red, in consequence of the
great number of minute vessels into which blood has penetra-
ted during inflammation ; and granulations will form on its
surface.

These vessels must have existed previously in the sound
state of the membrane, and conveyed a transparent fluid ;
although no structure of this kind was visible. This single
fact therefore proves completely its organization.

In some parts of the body, this cellular membrane appears
to be moistened by a small quantity of tfluid, or halitus, in its
cells ; which seems merely sufficient to keep it soft and flexi-
ble. In other places it is loaded with fat.

There is great reason to believe that the fat is contained in
cavities which are somewhat different' from the ordinary cavi-
ties of the cellular membrane.

The cells or cavities which contain the moisture or halitus
communicate with each other, over the whole body. Thus,
air insinuated into the cellular membrane exterior to the pleura,
in consequence of a fractured rib, will be diffused over the
whole body ; and produce the disease called emphysema. In
a patient who is affected with that species of dropsy called
anasarca, a portion of the fluid will be effused in the head and
upper parts of the body, after he has passed a night in bed in
a horizontal position ; but after he has been in an erect position
for some time, the fluid will be accumulated in the legs and
feet, or most depending parts of the body, in consequence of
its gravity.

It is well known in dissecting-rooms, that the effused water

I

408 THE CELLULAR MEMBRANE.

may be completely discharged from anasarcous subjects, by
making incisions in the feet and placing the subject erect.

Blood effused in the cellular membrane is sometimes dis-
persed in the same way ; an ecchymosis often appears in the
eyelids in consequence of a contusion on the upper part of the
head ; and similar appearances occur in almost every part of
the body, in consequence of»effusion of blood at a distance from
them.

The fat or adipose matter is not diffused in this manner :
wherever it is first diffused, it remains, uninfluenced by gravi-
ty, or the ordinary pressure.

Fat is not observed in every part of the body ; it is never seen
in the cellular membrane of the eyelids ; of the penis ; of the
lungs ; of the parts within the cranium ; as well as of several
other places. The inconvenience which would result from the
accumulation of fat in these placer is very obvious : and it is
equally certain that the cellular membrane in them must be
different from that in which fat is produced.

From these peculiar circumstances, relative to the adeps, it
has been inferred^ that there was a peculiar apparatus for the
production and retension of fat, superadded to the cellular
membrane ; and some anatomists, with a view to precision,
have called the part containing fat, Adipose Membrane, and
the other part Reticular Membrane.* They state that in drop-
sical subjects, who are much emaciated, the membrane which
in a healthy state contained adeps, is more ligamentous than
the ordinary cellular membrane.

It seems to be proved, by reasoning, that there must be a
considerable difference between these different parts of the
cellular membrane : but it ought to be observed that those parts
of the omentum which are especially appropriated to the
production of adeps, do not exhibit any peculiarity of structure.

This adipose substance is distributed in unequal proportions
in different parts of the body. In corpulent persons there is a

* See remarks on the cellular membrane, &c., by Dr. W. Hunter, in the
London Medical Observations and Inquiries, vol. ii,

ADIPOSE TISSUE.

409

considerable quantity of it, immediately under the skin, and
especially under the skin of the abdomen.

It is also between the muscles, in the orbits of the eyes ; in
the omentum and mesentery ; in the joints and the bones ; as
well as about the kidneys, and heart also, in elderly persons.
In the foetus, and for some time after birth, it appears to be
confined to the parts immediately under the skin, but it soon
becomes more diffused. — The fat in the adipose tissue, is
unorganized, and at the common temperature of the human
body, is almost fluid. On the latter account it produces that
softness and smoothness of the exterior, particularly obvious in
obese individuals. Its use, probably, besides contributing to
the roundness and softness of the exterior, is in part to protect
the body against the extremities of heat and cold, in conse-
quence of its being a bad conductor of caloric. It may be
considered also, as a deposit of nutriment held in reserve, to be
dissolved and taken up again by the absorbents, in a protracted
fast, or when any wasting disease has impaired the functions of
nutrition. Adipose tissue, belongs to the most simple structures
of the body. It differs from cellular tissue even to the knife
and eye, by the toughness and coarseness of its web, and con-
sists of completely closed membranous cells containing the more
or less fluid fatty matter. They are affixed according to Mas-
cagni, each one to an artery and vein, the branches of these ves-
sels by which the fat is deposited, being distributed around the
cell. The fat after being deposited in the cells becomes more
consistent by absorption ; it is kept moist by a serous secretion
from the walls of the cell, which effectually prevents its transu-
dation into the neighboring tissues. If the fat be reabsorbed,
the cells which have no communication with each other, col-
lapse and vanish. The diameter of these vesicles or cells, in
man, vary from T£g to ^ of a line ; in some places as in the
spinal marrow, they are still smaller — from the ^ to ^ part
of a line. In our larger domestic animals, they are of much
coarser structure. —

It is observed by dissectors that there are no subjects, how-
35

410 CELLULAR TISSUE.

ever emaciated, who are entirely free from fat ; except those
who have been affected with anasarca.

The cellular membrane has been already observed to form
granulations very promptly ; and it has been asserted that the
granulations, which arise from all the different parts of the
body when wounded, originate from the cellular membrane in
those parts.

Whether this proposition be true or not, to the extent abo've
stated, it is a fact that granulations, in some instances, seem to
have a cellular structure ; as the following case will prove.

A patient, with a compound fracture of the leg, which was
attended with a large wound, covered with luxuriant granula-
tions, was attacked with an oedematous swelling of the limb,
which increased suddenly to a great degree. While this was
going on, the granulations on the surface of the wound tume-
fied with the limb ; and, upon examination, appeared some-
what pellucid, with an effused fluid indenting by pressure,
precisely as the skin was indented.

The cellular membrane appears to have a most intimate
connexion with the skin ; and cannot be completely separated
from it by dissection. It is said that in certain cases of disease
where it is reduced to a slough, while the texture of the skin
remains unchanged, as in some species of anthrax or carbuncle,
this separation may be completely effected. In such cases the
under surface of the skin will appear to be composed of pits
or excavations, which penetrate very deep into its substance,
and which were occupied by the cellular or adipose membrane
while it was in its natural condition.

THE SKIN. 411

CHAPTER XL

OF THE SKIN.

The skin is composed of three dissimilar lamina, which are denominated the
Cutis Vera, the Rete Mucosum, and the Cuticula.

Of the Cutis Vera.

THE innermost of the above-mentioned lamina is much more
substantial than the others, and therefore is called Cutis Vera.

It is an elastic, dense, and strong membrane ; which contains
in its texture a large proportion of fibres that appear to be
tendinous, and are woven together in an intricate manner.*

Blended with these fibres is an immense number of vessels
which enter into the texture of the skin ; these vessels do not
generally convey red blood, and therefore they are not very
visible ; yet they may be readily brought into view, by the
application of rubefacients during life ; and by fine injections, in
the dead subject. Their existence is also demonstrated in the
vigorous infant, at birth, by the universal redness of the skin,
which is observable at that time.

Nerves are also distributed to every part of the skin. They
can be traced to it very easily ; and as there is no part of the
skin into which the finest needle can be pushed without pain,
it is certain that their distribution must extend to every part.

It is highly probable that the processes of absorption and
exhalation are effected by small vessels which originate or
terminate on the surface of the skin, and of course form a part
of its texture.

* These fibres hold a middle station between ligamentous and common cel-
lular tissue, and are supposed to consist of the latter in a very compacted state.
The innermost layer of fibres is of a reddish hue, and belongs to the class of
contractile tissues. It is to the presence of this red fibro-cellular tissue, that the
shrinking and wrinkling of the skin, called goose flesh (cutis anservia) is due.
The meshes, which the fibres of the skin leave when woven together, allow of
the introduction of vessels and nerves to the papillae on the outer surfaces of
the cutis vera.— p.

412 CUTIS VERA.

The skin, thus constructed, extends over the whole of the
body, and is continued into those cavities which open upon the
surface, as the mouth, nose, &c., although its texture changes
immediately upon its reflection.

It varies in thickness in different parts ; thus, it is thicker on
the back than the front of the body. It is thin on the insides
of the arms and leg, where opposite surfaces touch each other.*

It is, in general, thinner in women than in men.

The elasticity of the skin is made evident by its yielding to
distention, and returning to its usual size ; as in pregnancy,
dropsy, &c. ; but it is particularly demonstrated in some cases
of parturition, when the skin of the perinaeum stretches im-
mensely, and, after labor, very quickly recovers its size.

The external surface of the skin is very generally divided
by superficial grooves or sulci, into small spaces of various
angular forms ; most commonly rhomboidal. On the palms of
the hands and soles of the feet, instead of these figures, we
perceive the whole surface composed of furrows and ridges?
which, in some places, are rectilineal, and, in others, oval and
spiral.

There are also a number of depressions or grooves which
seem formed to accommodate the various articulations, particu-
larly about the fingers and toes.

There are other furrows, occasioned by muscles, as those on
the forehead ; and some depend on the subjacent cellular mem-
brane.

On the external surface of the true skin, when the two
exterior laminae are removed, many papillae are to be seen.
They differ in size in different parts of the body ; they are
vascular, and, on the ends of the fingers, appear like villi, when
examined by a magnifying glass.

There are many perforations or pores to be seen on the skin
with the naked eye, which are probably the ducts of sebaceous
glands, and the passages which transmit hairs. Other pores,
different from either of these, are to be seen when magnifying
glasses are used ; as those on the fingers ; these probably are

* The thickness on the back, is about double what it is on the front of the
body.— p.

SEBACEOUS FOLLICLES. 413

the exhaling or absorbing pores, but their connexion with the
vessels which perform these functions has not yet been demon-
strated. ./

The internal surface of the skin, when carefully dissected
from the subjacent cellular membrane, in a subject of ordinary
corpulency, appears to have some adipose substance in its
texture ; but, as has been already mentioned, when the cellular
membrane is destroyed, these portions of adipose matter
disappear, and the surface of the skin appears pitted. It is
probable that this connexion of the cellular membrane and skin
may occasion that delicacy of skin which appears in some
hydropic patients.

In some places on the under surface of the skin are small
glands called miliary, from their resemblance to the millet seed ;
these glands are supposed to secrete a sebaceous matter, but
they are not so general as has been supposed.

They are sebaceous follicles or ducts, which open on the
external surface of the skin, and contain an oily substance,
which, sometimes, has the consistence of suet or tallow ; when-
these ducts are filled with sebaceous matter, their orifices are
often covered by a black substance, which accidentally adheres
to the surface of the matter, and forms very small black spots
in the skin. These often occur on the nose and ears, and may
be removed by pressing out the sebaceous substance, which
rises up in the form of small worms. Sometimes this secretion
accumulates in the ducts in such quantities, that it forms small
tumors in the skin.

Fig. 107. — Fig. 107, is a portion of skin cut vertically
from the nose of an old man, in order to show
the sebaceous follicles and their ducts, which are
magnified much beyond their natural size. They are found in
all parts of the body, with the exception of the palms of the
hands and soles of the feet ; but in many parts only become
visible to the naked eye, in diseased conditions of the skin.
They are most numerous in the face, behind the ears, and in
the arm-pits and groin. There is a strong analogy between
them and the follicles of mucous membranes.
35*

414

SEBACEOUS FOLLICLES.

Fig. 108. — Fig. 108, represents the orifices of the

sebaceous glands, as they are seen in
the nose, after it has been deprived of
its epidermis. Each follicle consists
of a depression or doubling in-
wards of the cutis vera, which be-
cornjes more vascular and thin where
it forms the walls of the follicle. The
sebaceous follicles, according to E.
Weber, are much larger than and en-
tirely distinct from those forming the
bulbs of the hairs. The latter, too,
are situated more deeply, being often
found in the subcutaneous cellular
tissue. They differ also, according to him, in their structure ;
each sebaceous follicle being composed of four or five com-
partments or cells agglomerated together. They are also
larger than those of the bulbs of the hairs ; the largest diameter
of a sebaceous gland, (the transverse,) observed by Dr. Weber,
was three-fourths of a line. —

Muscular fibres have been supposed by some persons to
exist in the skin, but such fibres have never been demonstrated
in it. The skin of the scrotum is often much contracted, but
the fibres which produce this effect are very visible in the
cellular membrane, and have a muscular appearance.

Although the skin is not muscular, it sometimes changes its
appearance in a surprising manner.

When the surface of the body is suddenly exposed to cold,
or when the chill of fever exists to a considerable degree, the
skin will contract very sensibly, and, at the same time, a great
number of conical papillae will project from its surface. This
constitutes the Cutis Anserini ; and is supposed to be produced
by a sudden contraction of the vessels in the skin, which forces
out their contents, and of course, diminishes its bulk ; while the
papillae do not contract in the same degree, and, therefore, are
somewhat projected. Vide, article, contractile tissue.

When the skin is free from disease, the two exterior laminae,

RETE MUCOSUM. 415

(Cuticula and Rete Mucosum,) may be separated from it com-
pletely, after maceration or putrefaction, and the surface will
appear smooth ; but, in an inflamed skin, a net-work of vessels
has been injected, which is considered, by Mr. Cruikshank,*
as an additional lamen. In this lamen, the pustules of small-
pox originate. When the skin is injected, they appear to be
formed at first by very small vessels, arranged in a radiated
manner, with a white uninjected substance in the centre,
which is supposed to be a slough, occasioned by the irritation
of the variolous matter. Mr. Cruikshank, after removing this
lamella, was able, by continued maceration of the same skin,
to separate another, which was also vascular. It is to be
observed that this skin had been preserved for some time in
spirits, and was macerated in putrid water a week during the
heat of summer, before the first lamella was removed.

The color of the healthy skin is invariably white, when all
the lamellae exterior to it are removed. This is the case not
only with the European, but with the blackest African, and the
people of all the intermediate colors.

The variety of colors in the human species depends upon the
lamella next to the cutis, which is now to be described.

Of the Rete Mucosum.

Immediately in contact with the external surface of the cutis
vera is a thin stratum, of a pulpy or mucilaginous consistence,
which appears to be spread uniformly over it, but cannot be
detached without deranging its own texture.f

It can be best examined after the cuticle is raised in a blister.
In this case it appears like a pulpy substance, spread upon a
membrane of a soft and delicate texture. This is the Rete or
Corpus Mucosum.

In this pulpy substance resides the pigmentum or coloring
matter, which gives the peculiar complexion to the different
races of men. The cutis vera is white, and the cuticle is nearly
transparent in them all ; but this substance is black in the negro ;

* See Experiment on Insensible Perspiration, &c. by "W". Cruikshank.
f It has been asserted that the rete mucosum of the scrotum can sometimes
be exhibited in a separate state.

416 RETE MUCOSUM.

copper-colored, yellow, or tawny, in many of the Asiatics ; and
yollow, with a tincture of red, in the aborigines of America ;
while it is transparent, or whitish, in the people of Europe and
their descendants.

It can therefore be best examined in the negroes ; and if it
be inspected immediately after the cuticle of a blister is removed,
it will appear as above described, with a black matter diffused
through it.

The particular structure of this substance has not been ascer-
tained, although anatomists have paid a good deal of attention
to it. It is generally believed by them that no vessels can be
injected in it ; but Dr. Baynham of Virginia, while he was
engaged in anatomical pursuits in London, made a preparation
which excited the attention of the British anatomists, on account
of its particular relation to this subject.

He injected one of the lower extremities, the os femoris of
which was diseased with an exostosis ; and with a view to an
examination of the lamina of the skin, he removed a portion of
it from the leg ; and after immersing it a few seconds in boiling
water, to thicken the lamina, he macerated it in cold water for
some days. Upon separating the cuticle, after this treatment,
he discovered a texture of vessels on the surface of the cutis
vera, which was distinct from the cutis itself. This has often
been mentioned as injection of the rete mucosum.

It is to be regretted that Dr. Baynham, who is particularly-
qualified to decide, has pot published his opinion on the sub-
ject. Mr. Cruikshank, to whom he afforded the most satisfac-
tory opportunity of examining his preparation, believes that
the aforesaid vessels were not a part of the rete mucosum ;
but that the rete mucosum was to be seen on the epidermis,
(being raised with it when it was separated from the cutis,)
while this texture remained on the surface of the cutis. He
considers these vessels as belonging to the additional lamellae
already mentioned, of which he says Dr. Baynham is the dis-
coverer.

There is therefore every reason to believe that there is a
texture of vessels, either in the ret 3 mucosum, or between the
cutis vera and the rete mucosum.

CHANGE OF COLOR. 417

After putrefaction, or maceration for a long time, the cuticle
separates readily from the cutis vera ; and the rete mueosum
sometimes adheres to the skin, and sometimes to the cuticle.
If the parts are much softened by putrefaction, the rete
mueosum can be washed away, like the pigmentum nigrum
of the eye ; leaving the cutis white, and the cuticle nearly
transparent.

In the negroes the black color of the rete mueosum is
greatly diminished, on the palms of the hands, and soles of the
feet, and under the nails ; but it is perceptible. It is said that
the black color does not appear in the cicatrices of the blacks.
This is the fact with respect to recent cicatrices ; but those of
long standing are often dark-colored, although not so black
as the original skin. The pits of the small-pox in their skins,
although white at first, become finally as dark as the original
surface.

In Europeans and their descendants the color of the rete
mueosum becomes darker, as they are more exposed to the air
and the rays of the sun ; and soon changes again to its original
fairness, by confinement to the house.

In negroes the skin loses some of its deep glossy black color
during the winter season of cold climates, and recovers it again

o

in summer.

The rete mueosum sometimes undergoes very important
changes ; there have been several instances in the United
States, where large portions of the skin of the African have
changed from black to white ; owing probably to an absorption
of the black pigment from the rete mueosum ; or, perhaps, to
an absorption of the rete mueosum itself.

There is now in Philadelphia a female, between thirty and
forty years of age, in whom this process is going on. One of
her parents was a negro and the other a mulatto ; and her
original complexion accorded with her origin. But a change
of color began during her childhood, in small spots, which
have gradually increased so much, that at this time the whole
of her body and limbs are nearly white, with the exception of
her hands and feet. A large proportion of her face is also white,

418 CHANGE OF COLOR.

and the remainder of it much lighter than it was originally.
At this time, some part of her face has an unnatural whiteness ;
but the skin of her forearms appears like that of a European in
a perfectly healthy state. This change of color is attended
with no unusual sensation ; so that if she did not see the altera-
tion, she would not suspect that her skin was any way different
now from what it had originally been. She does not appear
sensible that the white parts are more susceptible of irritation
from the rays of tbe sun than they were originally ; but they
are so mnch covered by her dress that the experiment has not
yet been fairly made.

The first appearance of a change is slight diminution of the
dark color ; this change goes on gradually, and then small
spots appear, which are perfectly white. They gradually
increase, and run into each other, and thus a large white spot
is formed.

In a former case, where this process had gone on to a great
extent, it is said that the black pigment was again deposited,
and the skin resumed its original blackness.

These circumstances in negroes have been considered as
great deviations from the ordinary course of nature, but a
process very analogous to it sometimes goes on in persons who
are white. Thus, there are some in whom the skin becomes
much browner than natural in some parts of the body, parti-
cularly on the arms ; and in these brown portions, spots are
formed which are much more white than the natural color of
the skin.

In such cases there appears to be a deposition of coloring
matter in the rete mucosum of the brown places ; while the
white spots are rendered more white than natural, either by an
absorption of the rete mucosum, or by a deposition of whiter
matter in it.

The color of the rete mucosum sometimes undergoes a
temporary change in particular places. Thus, at a certain
period of pregnancy, a dark circle forms round the nipple.

In some cases, where the peculiar whiteness occurs, the skin
becomes very susceptible of irritation from the rays of the sun ;

ALBINOES. 419

so as to be blistered, if exposed to them for a short time ; this
circumstance renders it probable that the coloring matter in
the rete mucosum of the blacks, was originally designed to
protect their skins from the very powerful rays of the sun to
which they are exposed.

There are some persons to be found, amongst most of the
different races of men, who are born with this peculiar whiteness
of the whole skin, which continues during life. In these
persons, the hair has a remarkably white color, and the eyes
are without the pigmentum nigrum. They appear to be in a
state of imperfection, and are unable to endure the ordinary
light of day. They are generally designated by the epithet of
Albinoes.

The texture which exists between the cutis vera and the
epidermis is probably the principal seat of several important
cutaneous diseases ; as the Scarlatina Pemphigus, &tc.* and
from what has been stated, there is good reason to believe
that the small-pox, also, commences in it. It is, therefore,
much to be wished that its structure was more precisely ascer-
tained.

— The variety of diseases which have their seat in the skin,
as well as the important functions which it exercises in health,
have led modern anatomists to believe that it was formed of
more than the three layers that Malpighi assigned it, and
induced them to investigate its structure with scrupulous care.
From the innate difficulties of the subject, its anatomy cannot
as yet, however, be considered as satisfactorily made out, for
its investigators have too frequently resorted to hypothesis,
when the means of demonstration failed them. The doctrines
of the learned and judicious Malpighi, which have been admi-
rably detailed above, were generally admitted by anatomists,

* In severe cases of the scarlatina, at the termination of the disease, large
portions of the cuticle are sometimes detached from the cutis, so that several
practitioners have seen the whole cuticle of the hand come off like a glove. As
the texture of the cutis does not appear to be altered in these cases, and the
cuticle is also unchanged, the cause of this separation must exist in the inter-
vening structure which connects them.

420 STRUCTURE OF THE SKIN.

till M. Gaultier,* a mere student of medicine, full of zeal and
candor published in 1813 his researches on the skin, which,
though imperfect in some respects, went far towards establishing
its real structure.

— The rete mucosum, which Malpighi considered a simple
coating of mucous, between the cutis vera and cuticle, a sort of
varnish covering the papillae, was considered by Bichat as
essentially formed of vessels, and divided by him into two
vascular layers, one over the other, in the outermost of which
was placed the coloring matter or pigment. But Gaultier,
from his observation of the skin of the negro, and Dutrochet
from that of quadrupeds, consider it composed of many distinct
parts. Gaultier selected for observation the skin of the heel of
a negro. where the cuticle is thickest, but which he thought
differed in no other respect from the skin in other parts of the
body.

— This figure is a magnified representation of a section of

the skin cut obliquely in regard
to its thickness, and transversely
to the lines formed by the
papillae. In this, according to
Gaultier, we see at 1 the lower
surface of the derm, or cutis vera. 2, The prominences or as-
perities of the derm, forming the papillae, each one with a
slight depression upon the top. 3, Immediately above these
and continuous with them we see a series of vascular fasci-
culi surmounting these prominences, called bloody pirn-

* Gaultier, whose opinions have been adopted in the main by Beclard, Blan-
din, Cloquet and others, would, if he had lived, most probably done much
towards simplifying and perfecting his views. Appointed army surgeon imme-
diately after his graduation, he fell a victim to the disasters of the Russian,
campaign. The investigation has, however, been taken up by Dutrochet who
extended it to the skins of quadrupeds, by several of the German and Italian
anatomists, and lastly by Breschet and Roussel de Vauzeme. The last have
made it a subject of elaborate microscopical research, not only in man, but in
the whale and many of the larger animals. The views of Gaultier thus modi-
fied and improved, are well deserving of study as the most satisfactory yet
given, though, from the doubt which is always attached to microscopical
observations, they must be looked upon rather as the probable than the proven
structure. — r.

ACCORDING TO GAULTIER. 421

Fig. 1 W.* pies, (bourgeons sanguins.) 3, The tunica albida

§& profunda, covering these papillae upon their top
ft and sides, and united to the upper surface of the
' derma, and composed entirely of white vessels,
(serous capillaries.) 4, Gemmules ; a sort of membrane so
named from its undulations, excavated on its internal face,
which covers in the tunica albida profunda. This is the seat of
the coloring matter of the skin, and each undulation receives
two of the bifid tops of the papillae, called bourgeons sanguins.
5, Tunica albida superficialis, which covers over the gemmules,
and is also formed entirely of white vessels. 6, The external face
of the skin, which is only the dried surface of the tunica albida
superficialis, or the proper epidermis. Gaultier considers four
of these layers as belonging to the rete mucosum ; the perpen-
dicular vascular fasciculi (bourgeons sanguins,) the gemmules
and the two white tunics.

Fig. lll.f — The first and second of these

four, correspond with the two
vascular layers which Bichat as-
signs to the rete mucosum ; and
the views of Gaultier differ from
this writer's in his adding two more tunics, tun. albid. profun-
da, and tun. albid. superficialis. But the vascular fasciculi,
as Dutrochet and Beclard have asserted, belong to the cutis
vera, and form a part of the proper papillary body ; and were
probably the parts injected by Baynham and Cruikshank —
thus leaving the rete mucosum formed of three layers. Thus
modified, Gaultier's researches have been adopted by many
writers.

— But there were not wanting others who entertained different
views. Gall believed the rete mucosum a nervous expansion

*Fig. 110, — Is a representation of the skin, and the basis of the papillae,
the latter surmounted by the vascular villi or fasciculi, (bourgeons sanguins.)
The space between these fasciculi is filled up, in the natural state of the parts,
according to Gaultier, with the tunica aibida profunda.

f Fig. Ill, — Is a representation of the derm, or cutis vera, with a line of
prominences on its upper surface, constituting the basis of the papillae.

36

422 • STRUCTURE OF THE SKIN

for the reception of tactile impressions; an opinion purely hypo-
thetical and erroneous ; Chaussier, that the skin was composed
of but two parts, the dermis and epidermis, and that
which had been called the rete mucosum was probably a
part of the dermis ; Blandin,* that the rete mucosum, consist-
ing of three layers according to Dutrochet placed between the
papillary bodies and the epidermis, had neither vessels or
nerves, was a product of secretion from the papillae, like the
epidermis, and formed in fact a second epidermis thicker and
softer than the external, and that it had no more vitality than
the hair and nails.

— -Breschet and Roussel de Vauzeme,f have in this uncertain
and imperfect state of our knowledge, endeavored with the
aid of the scalpel and the microscope, to determine positively
its structure. Their researches have been extended not only
to the skin of man, but to that of whales and others of the
cetaceae. The discoveries which they allege to have made are
surprising, and though their researches appear to have been
made with much labor and ingenuity, their confirmation
or overthrow must depend upon the investigation of others
equally familiar with the same instruments.
— But it must not be forgotten that such high magnifying
powers as they have used, expose the most wary and honest
observer to optical illusions. This cause led De la Torre, to
assert that the globules of the blood were annular.
— According to these writers, the skin consists of but two layers.
The derm, or cutis vera, and an external layer, which they call
indifferently epidermis, corneous matter, corneous tissue, or
epidermic layers. This external layer comprises the rete muco-
sum and epidermis of other writers, and they consider it composed
of the same substance, mucus, in a greater or less state of desic-
cation. It is, however, composed of many distinct parts, not
arranged in the form of layers. Fig. 112, represents an imagi-
nary scheme or plan, in which they have placed together the

* See Anat. Generale of Bichat, Paris, 1831.—

f Nouvelle recherches sur la structure de la peau, par G. H. Breschet and
Roussel de Vauzeme. — Paris, 1835. —

ACCORDING TO BRESCHET AND ROUSSEL DE VAUZEME. 423

constituent parts of the skin, the existence of which they had
proved separately under the microscope.

— Thus, a is the derm, b, The corneous or horny epiderrmic
matter, c, The vessels and nerves which go out from the der-
mis. d, Space filled up by their capillary branches, e, Ner-

Fig. 112.*

vous or tactile papillae. The diapnogenous, or sudoriferous
apparatus, composed of a glandular parenchyma,/, and of spi-
ral sudoriferous canals, g. The glandular or secretory organ is
inclosed in the substance of the skin, and the canals pass up
between the papillae and open obliquely on the surface of the
epidermis, constituting the microscopical orifices, from which
we see the sweat exuding on the palms of the hand, and soles
of the feet. A, The inhaling apparatus, or absorbent canals,
which resemble in many respects the lymphatic vessels : they
are situated in the corneous matter, or rete mucosum ; they are
seen to commence under the most superficial layer of the corne-
ous matter which forms the cuticle ; no mouths or orifices are
seen, and it is impossible to say, whether they commence in the
form of a cul de sac or not. They pass down between the papil-
lae, by the side of the sudoriferous canals, and communicate with

424 STRUCTURE OF THE SKIN

a net- work of vessels, which they believe to be lymphatics
mixed up with veins, spread upon the surface of the derm.*
it The organs which secrete the mucus, of which the rete mu-
cosum and cuticle is formed, or blennogenous apparatus ; this
consists of a glandular parenchyma situated in the thickness of
the derm, and of short excretory canals fr, which deposit the
mucous matter between the Abases of the papillae. The chro-
matogonous organs or glands, which secrete the coloring
matter or scales, run parallel with, and immediately below the
grooves on the surface, and between the papilli, which they
are also placed a little below. The ends of them, marked by
a collection of dots, can of course only be seen in the plan, in
consequence of their running parallel with the grooves, and
between the parallel ranges of papillae.

— They consist of a glandular parenchyma, receiving an abun-
dance of capillary vessels from the derm below, and possessing
excretory canals above, that throw upon the surface of the
derm, the coloring principle, which is mixed with the soft and
diffluent corneous or mucous matter, secreted by the blennog-
enous apparatus. From this mixture results the pretended
rete mucosum of Malpighi, and the epidermis or cuticle.
From this apparatus is also produced, they think, the horns,
scales, spines, bristles, hair, wool, hoofs, nails, etc. of different
animals. It is solidified in successive couches, to the right and
left, as seen in the section across the grooves, /; but in the
longitudinal section m, these layers present a series of straight
lines one above another like the leaves of a book.
— In consequence of this arrangement, the corneous matter,
when macerated, throws off layer after layer. The superior
face of the epidermis presents grooves, as represented at n,
which correspond to the interpapillary grooves of the derm,
o, Are the prominent ridges in the cuticle formed over the
papilla, separated by transverse grooves, p, at the bottom of
which are found the pores of the sudoriferous canals, e, Are

* The existence of these inhalent vessels, from some observations I have
made with a very powerful microscope, I should consider extremely doubtful. — P.

ACCORDING TO BRESCHET AND ROUSSEL DE VAUZEME. 425

the vessels and nerves which enter into, or go out from the derm.
d, An interval filled up by capillary filaments.

Of the Derm,

— The external surface of the derm, is lined by a very thin
adherent membrane, which is reflected over the tops of the
papillary bodies and forms their neurilema. The horny or
epidermic matter is secreted in the grooves between the papillae,
and is moulded around all the inequalities, the form of which is
exactly impressed on all the layers of the epidermis. In serpents,
the derm, has a singular arrangement ; it is elevated in imbri-
cated projections, covered by a thin layer of epidermis ; these
are called scales. In fishes, on the contrary, the surface of the
derm is smooth, and the scales are formed only of the horny
matter. The derm is a membrane, the fibres of which are
solidly interlaced together, with interstices for the passage of
vessels, nerves and canals, and in which are lodged many
organs, as has been shown in the plan, page 423.*

Of the Papillary Body, or JNeurothelic Apparatus.^

— This consists of a series of little prominences on the upper
surface of the derm, the cleft at the top into two portions, each of
which is composed of a bundle of nerves and vascular fila-
ments— the bourgeons sanguins of Gaultier. The form of each
papilla is that of a cone. The base is expanded in the upper
surface of the derm, and its two prominences or villi, termi-
nating in a rounded point, are received in the horny layers of
the epidermis, like a sword in its sheath, (see page 426.)
— The direction of the papilla is slightly oblique in the epider-

«

* The method adopted by these writers for microscopical examination of the
skin, was to take a piece of recent skin in which the vessels were distended by
cadaveric accumulation of blood, or filled with injection. A portion from the
heel is preferable. This is to be allowed partially to dry, and the thinnest pos-
sible transparent slice, cut off vertically. This is to be placed upon a piece of
moistened glass and examined under the microscope with the use of a lamp
and reflector. In this way they were able readily to see, and isolate with curved
cataract needles, all the vessels, nerves and glandula apparatus of the skin.— p.

f From ne.uron, nerve, and thtla, papilla. —

36*

426 STRUCTURE OF THE SKIN

mic layers, as seen in fig. 113.* The nerves are here seen
passing up into the papillae through the dermis ; the vascular
branches which accompany them are not here represented.
The papilla first gets a neurilema/ic covering from the upper
surface of the derm, and is there furnished with several layers
Fig. 113.f of the epidermic horny matter, which

cover it like a hood. This horny cov-
ering is particularly thick at the heel,
and serves to protect the papillae by the
deadening of shocks, and resisting the
pressure of the weight of the body.
The papillae are most numerous on the
palms of the hands and soles of the
feet, but are also scattered over other
parts of the body.J

Of the Sudoriferous or Diapnogenous
Apparatus.

— This consists of a gland, see fig. 112, p. 423, placed in the
substance of the dermis, near its inner surface, into which a
great many capillary vessels run, and of a spiral duct which
runs up through the horny layers and opens obliquely through
the outer epidermic crust by a slight depression or pore, on the

* According to these writers the nerves, as they pass up from the under sur-
face of the skin, becomes soft, flexuous, and capillary, and as they enter the
villi on the top of the papilli, lose their neurilema, and are expanded in the
form of pulp. They look upon the changes which the nerve undergoes, and
upon the derm, villi, and epidermic covering, as so many parts necessary to
constitute the perfect organ of touch : thereby assimilating it to the more com-
plicated organs of sight and hearing. — Loc. cit. p. 15, et seq. —

f Fig. 113, represents the apparatus which constitutes the organ of touch in
man. a, Nerve entering into the dermis, where it becomes capillary, b, Its
entry into the papilla, c, Neurilema furnished by the dermis. d, Proper envel-
op of the nerve, e, Corneus layers more or less thick, which form the organ of
protection to the nerve. The capillary blood-vessels which pass up with the
nerves are not here shown.

$ From their observations upon the papillae of the whale, these anatomists
are disposed to believe that the nervous fibrils terminate at the top of the villi,
by loops with one another, as Prevost and Dumas have shown them to do in
other parts of the body. —

ACCORDING TO BRESCHET AND ROUSSEL DE VAUZEME. 427

back of the epidermic ridges, formed over the papillary bodies.
These are the orifices from which the sweat exudes, and may
be readily seen with a single lens of moderate magnifying
power, on the palms of the hands, soles of the feet, nose, and
other portions of the body. The obliquity of the orifice, gives
it a valvular arrangement, like that of the ureters where they
enter the bladder. In consequence of this the valve closes the
orifice, when the epidermis is raised by cantharides, and the
duct is broken off, so that the pores are not generally visible ;
this has occasioned some anatomists, of great reputation, (J.
F. Meckel, Cruikshank, Blumenbach, etc.)* to deny altogether
the porosity of the epidermis, and to believe that the sweat
passed by exudation or exosmosis directly through its sub-
stance. In carefully elevating the cuticle from the subjacent
coats, these ducts are visible as very fine transparent elastic
filaments ; the spiral being converted into straight tubes by the
traction, and which W. Hunter, Bichat, and Chaussier, accord-
ing to these writers, mistook for the exhalent and absorbent
vessels.f Others supposed they were filaments of cellular
tissue, uniting the epidermis to the subjacent layer.J The
sudoriferous organs, which are exceedingly numerous, are
probably the only exhaling organs of the skin.

The Inhaling Apparatus.

— This is properly an appendage of the absorbent system ; and
may be seen, according to these anatomists, with a lens of
feeble magnifying power, or even with the naked eye, in rais-
ing the epidermis with proper precaution. They have not,
however, been enabled to make out their anatomy satisfactorily.

* Beclard was disposed to consider these pores as the orifices of the sebace-
ous glands, though he expresses himself doubtingly upon the subject, and says
that the rout by which the sweat traverses the epidermis is entirely unknown. — p.

f The existence of exhalent vessels, was a mere presumption of Bichat, and
has never been demonstrated. — p.

| Eichhorn has also observed these sudoriferous canals, and his description
of them corresponds in' many respects with that of Breschet. (Memoire sur
les exhalations que se font pour le peau, et sur la voies par lesquelles elles sont-
lieu ; par Henri Eichhorn.) Arch, de Meckel. — p.

428

STRUCTURE OF THE SKIN

They describe them, see fig. 112, as arising by isolated radicles
from the under part of the grooves of the epidermis, and not
opening to the surface ; the fluids which they take up getting
into their cavities by previous imbibition through the outer
cuticular covering. In passing downwards towards the derm,
they are in company with the sudoriferous ducts, and in the
substance of the derm, becomes continuous with the common
absorbent vessels.*

Fig. 114.f

Blennogenous Apparatus,

— Or organs that produce the mucous substance, which, in
its first soft condition, forms the mucous body, heretofore
known under the name of rete mucosum, and which, hardened
upon the surface constitutes the horny matter of the epidermis.

* The existence of these absorbent vessels immediately beneath the cuticle
and on the upper surface of the dermis, has been demonstrated by Tiedemann,
Fohman, and Lauth. Breschet asserts the discovery of an additional structure,
in his inhaling apparatus, arising in the corneous tissue.— p.

f Fig. 114. — a, Chromatogenous organ torn in two places, b and c, to show
the escape of the scales, and the thread-like vessels of which this organ is
composed, d, Its small excretory canals, torn in removing the corneous mat-
ter, e, Blennogenous or mucous gland, which throws its secretion above the
chromatogenous organ. /, Fluid state of the corneous matter, that is to say,
pigmentum or scales floating in the midst of mucus, (rete mucosum of Mal-
pighi.) £, Layers of corneous or horny matter stratified to the right and left,
more and more condensed, the nearer they approach the surface. Into the
mucous gland is seen running a sanguineous vessel, and round it are placed a
number of little whitish granules.

ACCORDING TO BRESCHET AND ROUSSEL DE VAUZEME. 429

To see these well with the microscope, it is necessary to have
a piece of fresh skin well injected with blood. There is then
to be seen at the base of the derm, little reddish glands, irregu-
lar on the surface and grooved by blood-vessels. They are
enveloped in cellular membrane and surrounded by a multi-
tude of minute adipose vesicles. From the top of each of these
glands as seen in fig. 114, passes up a duct, which opens on
the upper surface of the derm in the grooves between the pa-
pillae. Many capillary vessels adhere to the tube and the
gland, and a vessel of considerable size enters the base of the
latter. The mucous matter thrown on the surface of the derm
by these organs, quickly unites with a coloring matter, from
which results the different tints of the corneous or epidermic
substance, hair, nails, scales, feathers, etc. in man and other
animals. This coloring is formed by the

Cromatogenous* Apparatus, (see Jig. 114,)

— which is placed at right angles to the ducts of the mucous
glands, at the upper surface of the derm, and at the bottom of
the grooves. Its structure is parenchymatous or spongy. On
its under surface, it receives a great number of minute capillary
vessels, which is the outer limit of the vascular system, with the
exception of the vessels which pass up into the villi. On its
surface arises many short ducts, and which open in the grooves
between the papillae, to convey up the coloring matter in the
form of small granules to mix with the mucus.f When this
tissue is torn, a great many small filaments are seen (a,) from
which escape small scales or colorless corpuscles in great
quantities, (b, c.) This reservoir of scales is found in no other
part of the derm.

— At/*, is seen the fluid state of the corneous matter — that is
to say, the pigment of the scales floating in the midst of the
mucus. At g, couches of this matter, hardened and stratified,
to the right and left as they approach the surface, form the

* From x/>cj/m, color, and yewau, to create. — p.

f The coloring matter as is very obvious in the black, is now found to be
deposited in delicate hexahgedral cells which are called pigmentary cells. In the
choroid coat of the eye the cells are arranged in several layers over each other,
so as to form a pigmentary membrane, the surface appearing perfectly black.

430 OF THE CUTICLE.

coverings of the papillae, and which are thus secreted and
moulded around these organs.

— The whole of the corneous tissue of the skin, (included
usually under the terms of rete mucosum and epidermis,) is
formed according to these anatomists of the mingled products
of these mucous and coloring glands.*

The Cuticula or Epidermis,

has been examined with the greatest care by several of the
most successful anatomists ; but notwithstanding their labors,
the structure of this substance is by no means understood.

It appears to have some resemblance to the matter of the
nails, and of horn : but is rather more flexible, even after
allowing for the difference in thickness.

In those parts where it is thinnest it is semitransparent.

It is insensible, and no vessels can be seen in it.f

* In investigating this obscure and difficult part of anatomy, it has been
usual with observers to select the skin of the palms of the hands and soles of
the feet, as a type of the whole cutaneous system. There is, however, a
difference to be observed. In the palms and soles resides pre-eminently the
sense of touch. These parts are likewise destitute of hair, and the papillae
which are there very numerous and visible to the naked eye. are very sparsely
distributed and appear rudimental in other parts of the body. Much of the
discrepancy among anatomists in regard to the structure of the skin, appears
to be owing to whether they have made their researches mainly upon the palms
and soles, or upon the skin of other parts of the body. Chevalier* and Wallace,!
have described especially in the skin of the face, arms, and legs, a system of
epidermoid glands, seated in the rete mucosum, and so minute that the latter
counted one hundred of them in the one-twenty-fourth part of a square inch,
and which gave issue to the sweat. These appear to me, to correspond with
the diapnogenous apparatus of Breschet, as he represents them in the palms and
soles.

The opinion of Bichat, is therefore erroneous, that the sense of touch is only
more perfect in the hands than other portions, in consequence of the shape of
the parts, and the facility with which they may be applied round objects, and
that the skin of the abdomen substituted for that of the fingers, would have
constituted organs of touch. — p.

f In the early part of the last century, an anatomist by the name of St.
Andre, exhibited a preparation of the cuticle which appeared to be injected
with mercury. Ruysh declared the thing impossible, and invited him to an
investigation of the subject. This invitation was not accepted, and the affair
has been generally considered as a mistake or an imposition. — H.

* Lectures on the general structure of the human body, and on the anatomy and functions
of the skin, by J. Chevalier.

t Lectures on the structure of the skin, by W. Wallace, London Lancet, 1837.

OF THE CUTICLE. 431

It extends over the whole external surface of the body,
except the parts covered by the nails, and is accommodated to
the surface of the skin, by forming ridges or furrows, cotfes-
ponding to it.

It adheres most closely to the cutis ; and when abraded by
mechanical violence, the surface of the skin appears moistened
by effusion.

It is not certain that its mode of union with the skin is
perfectly understood ; the adhesion of these membranes to
each other is as uniform as that of two smooth surfaces glued
together, but it is generally said that the cuticle is attached to
the cutis by very numerous and fine filaments.

It has often been asserted that these filaments are the
exhaling and absorbing vessels, which pass through the cuticle,
to and from the skin. This sentiment appears very reasonable,
but no vessels that pass in this way can be injected.

There are innumerable processes which pass from the cuticle
to the skin. Many of these are the linings of the cavities which
contain the roots of the hairs ; but they are reported by micro-
scopical observers to be like the fingers of a glove, closed at
their extremities.

There are also many processes which contain a sebaceous
substance that may be pressed out of them in the form of
worms ; these are the ducts of sebaceous glands.

Besides these, there is an immense number of whitish fila-
ments, which are as fine as the most delicate thread of a spider's
web. These filaments can be best seen while the cuticle is
separating from the skin of the sole of the foot, as suggested by
Dr. William Hunter.* They are supposed to be vascular, but
they have never been injected.

When the cuticle is in its natural situation, in union with the
skin, there appears to be three species of foramina or pores, on
its external surface: viz. 1. Those formed by the passage of
the hairs ; and 2. Those which are the orifices of the ducts of
the sebaceous glands ; each of which has been already men-

* See the London Medical Observations and Inquiries, vol. ii, — n.

432 OF THE CUTICLE.

tioned. And 3. Such pores as exist on the ends of the fingers
and the inside of the hands.

It is said that these last are very visible, when magnified to
twice or thrice their original bulk, and drawings of them have
accordingly been made by Dr. Grew* and by Mr. Cruikshank.f
Small specks of fluid can be seen with the naked eye, in the
same situations, in warm weather, or when the ends of the
fingers are made turgid by a ligature. It is probable that they
are formed by the accumulation of fluid at these orifices.

The above described pores are situated on the ridges at the
ends of the fingers and not in the furrows ; and it is probable
that similar pores are distributed over the surface of the body.
, Notwithstanding the appearance of these foramina, when
the cuticle is in its natural situation, several of the most suc-
cessful investigators of the subject have declared that they could
not discover any pores or foramina in the cuticle, when it was
separated from the cutis.

The late Professor Meckel of Berlin, who was one of this
number, was induced to believe that the matter of exhalation,
and of absorption, soaked through the cuticle, as the vapor of
warm water passes through leather.f

In support of this doctrine he states that perspiration goes on
through the cuticle on the palms of the hands and soles of the
feet when it is very thick ; and observes, that if it were trans-
mitted by delicate vessels, the vessels in the feet must be torn
by the weight of the body, in persons who walk ; and those in
the hands would experience the same fate, in laborers, who work
with heavy hammers, &tc.

On the other hand, Mr. Cruikshank, who could likewise find
no pores in the separated cuticle, contends strenuously for their
existence notwithstanding ; and explains their non-appearance
by the following facts, among others ; viz. that no foramen will
appear in the separated cuticle, although it has been punctured
by a needle ; and that when the cuticle has been peeled off,

* In the Philosophical Transactions, vol. iii. Lowthrop's Abridgement.

f See his Experiments on Insensible Perspiration.

$ See Memoirs of the Royal Academy of Sciences of Berlin, vol. xiii. for 1757 .

CAUSES WHICH PRODUCE VESICATION. 433

from portions of the cutis on which were hairs which must
necessarily have perforated it, no foramina have appeared
in it.

M. Bichat took very different ground : he asserted that the
pores of the separated cuticle were to be seen distinctly, in
large numbers, by looking through it towards the light ; he also
believed that the course of the exhalent vessels, through the
cuticle, might be seen in the same manner; and that they
passed obliquely.

That the cuticle is pervious, is proved incontestably by the
functions of perspiration and sweating, as well as of absorption ;
but there are good reasons for believing that the perforations
of the cuticle have a peculiar structure ; and are not simple
foramina. Thus, when a vesicle is formed by the operation of
cantharides or any other process, if the cuticle is not lacerated,
it will confine the effused fluid for a considerable time, without
any appearance of its escape through these pores.

This fact, which is strongly opposed to the hypothesis of
Meckel, is explained by Cruikshpnk upon the supposition that
the pores of the skin are lined by processes of the cuticle, and
that when the cuticle is separated from the cutis, these pro-
cesses go with it, and act like valves in confining the fluid.

Bichat supposes the oblique vessels to produce the same
effect upon analogous principles ; and compares their situation
to that of the ureters, which pass obliquely between the coats of
the bladder.

This peculiar quality of the cuticle, in admitting of perspira-
tion and sweat, and also absorption, while it prevents evapo-
ration from the parts which it encloses, is of immense impor-
tance.

If a portion of skin be deprived of cuticle a short time before
death, by a blister for example, this portion will, in a few days,
become perfectly dry and hard, like horn ; while the other parts
of the skin of the subject, covered by the cuticle, retain their
moisture and flexibility.

It may, therefore, be admitted, that the use of the cuticle is
to keep the -skin soft and flexible, by confining its moisture, as
37

434 SEPARATION OF THE CUTICLE.

well as to defend it.* And it is probable tbat the sebaceous
matter is secreted for the purpose of preserving the cuticle in a
state of flexibility.

As the cuticle is capable of confining fluid, and resisting the
action of chemical agents, it is surprising that epispastics and
rubefacients should act through it, upon the skin, with so much
certainty as we find they do»; and that cantharides should pro-
duce vesications, when applied dry.

The thickness of the cuticle on every part of the body is
much increased by long continued pressure, forming corns and
excrescences of its own nature. By this cause also it is ren-
dered very thick on the palms of the hands and soles of the
feet ; although it is originally thicker there than in other parts.

It is said that, after long boiling, these thick portions of cuti-
cle may be separated into distinct lamina.

In the living subject, the cuticle, when immersed in warm
water, seems to absorb some of that fluid ; as is evinced by the
hands when they have been long in that situation ; and also by
those parts of the skin to which poultices have been applied.

Notwithstanding the uniform adhesion of the cuticle to the
cutis, it is observed, in the living subject, to be separated, and
formed into vesicles, by a variety of causes, viz.

1. Pinching of the skin, or violent mechanical irritation ; such
as laboring with hard instruments.

2. By the application of cantharides, and certain other sub-
stances which produce vesications. Sometimes these sub-
stances appear to inflame the skin ; but on other occasions the
vesication is produced while the skin appears unchanged in
color, and free from inflammation. The process appears dif-
ferent from that of simple inflammation ; for certain rubefa-
cients often inflame the skin considerably without vesicating or
blistering it.

3. Boiling heat will, very generally, produce vesication.

4. Certain diseased processes seem to occasion vesication in

* This property of the cuticle is rendered very apparent in attempting to dry
anatomical preparations with the skin on, in which the student will fail, unless
the cuticle is previously removed by maceration. — p.

CHEMICAL, QUALITIES OF THE CUTICLE. 435

a manner which is not well understood, viz. erysipelas, zona,
or shingles, pemphigus, and some other eruptions which have
no name. In erysipelas there is an obvious inflammation of
the skin ; but in some of the other diseases the vesication takes
place without the appearance of inflammation.

5. Vesications often appear when there is a tendency to
gangrene.

6. They also occur in some cases of simple fracture, where
there is considerable injury. In these cases the fluid effused is
often tinged with blood.

After death the cuticle is separated from the cutis :

1. By putrefaction; in which case large vesicles are some-
times formed.

2. By long continued maceration,

3. By boiling, and

4. By violent dry heat.

The cuticle appears to be least deranged when it is separated
by putrefaction and maceration : in these cases the internal
surface corresponds to the surface of the skin ; and the pro-
cesses which contain the hairs, as well as those which are the
ducts of the sebaceous glands, are particularly obvious.

The external surface of the cuticle varies in different places,
according to the surface of the skin. In some places it appears
scaly at times, and has therefore been supposed to consist
entirely of scales ; but in other parts, when examined atten-
tively, it appears like a half transparent concreted substance,
with a rough surface.

When the skin has continued dry for a long time, bran-like
scales can be rubbed off from it. These are probably com-
posed of the residuum of the secretion deposited on the skin,
and of a portion of the external surface of the cuticle. The
same substance appears upon the first washing of the skin, after
that process has been discontinued for any length of time.

Many speculations have arisen respecting the manner in which
the cuticle is originally formed, and reproduced ; but none of
these are perfectly satisfactory.

It is also a question whether the cuticle is endued with vitality,

436 CHEMICAL DUALITIES OF THE CUTICLE.

or is merely an inanimate unorganized concrete. No decisive
argument have been adduced in favor of its vitality ; and it
has already been stated, that neither nerves nor vessels can be
demonstrated in it.

It appears particularly calculated for protecting the skin
which it covers ; for it is insoluble in water, and resists the
action of several powerful Chemical agents. Thus, it is not
affected by immersion for a considerable time m the sulphuric
and muriatic acids ; although the nitric acid acts upon it.

It resists for a short time, but is at length dissolved, by the
pure fixed alkalies, and by lime.

It is supposed by the chemists to consist of albumen, in a
peculiar state of modification.

— Malpighi, was the first to discover, by the use of the
microscope, an intervening substance between the cuticular
covering, and the cutis vera, which he called the rete mucosum
or corpus reticulare. This he considered the seat of coloration
in the negro, and asserted the cuticle to be alike in all varieties
of the human race — that is, colorless. For a long period his
researches formed the basis of all the systematic treatises upon
the skin, and it is only within a recent period, as has before
been observed, that the study of the subject has been resumed.
— The cuticle of the black is now generally admitted to be of
an ashy color.* And Flourensf has shown, that the reticular
appearance of the rete mucosum is entirely an adventitious
circumstance. Malpighi first discovered his rete mucosum on

* Breschet has asserted that the color of the skin in different animals is
dependent upon the form of the scales of the epidermis, by which the light is
reflected.

Fig. 115. The larger cut represents, after this observer, the

scales of the epidermic or corneous matter of a
white man, diluted with water, and highly magni-
fied, in which are seen fragments of the sudoriferous
canals and inhalent vessels. The scales all have a
trapezoidal or lozenge shape. The smaller cut,
represents a single scale from the skin of a whale,
highly magnified. It is black at its summit, and
whitish at its pedicle of insertion. The skin of the whale is black, and these
writers assert, that in all animals with black skins, including negroes, the scales
of the epidermis, appear under the microscope of this shape or spatulate. — P.
f Annales des sciences naturelles, 1837. —

CHEMICAL QUALITIES OF THE CUTICLE. 437

the tongue of the ox, and subsequently under the epidermis of
the human hand, from which he drew his description. By
ebullition he softened the outer covering of the cutis vera,>6nd
then tearing off the epidermis, he saw a layer of soft substance
with holes in it like the meshes of a net. This was owing to
a laceration of the mucous layer: the part covering the apices
of the villi going off with the cuticle, while that between the
villi and the bases of the papillae adhered to the cutis vera.
By maceration in water, which is the surest and most success-
ful method of effecting a dissection in delicate parts, FJourens,
found in the same organs the cuticle to come off, leaving the
whole of the mucous body attached, which then presented none
of the reticular appearance. The cuticle arid mucous body
were both continuous layers, covering the papillae and forming
their sheaths. The sheaths formed by the latter body were
broken in Malpighi's preparation.

— The cuticular sheaths in the ox, were thin and delicate over
the fungiform or smaller papillae, but formed thick horny layers
over the larger which assist in the action of mastication.
— Albinus, repeating the experiments of Malpighi, corrected
his error, and in the beautiful designs of Ladmiral, has repre-
sented the mucous body as a continuous layer. Since then by
Bichat and others, the use of the term rete mucosum, has been
continued, not exactly in the original signification of Malpighi,
but under the belief that it contained a net-work of vessels.
Its foliated structure has been well established by Cruikshank,
Gaultier, and Flourens. It thus appears that the whole of
the anatomy of the skin, requires to be constructed anew.
Several of the German and French anatomists have applied
themselves to the task, among whom may especially be men-
tioned Weber* of Leipzig, and Breschet of Paris.f The views
of the latter, on account of his having treated the subject more
extensively than the rest, as well as from his high situation in
the school of Paris, have already been given. The physiology

* Arch, fur die Physiologic. —

f Nouvelles Recherches sur la Structure de la Peau, par G. W. Breschet et
Roussel de Vauzeme. Paris, 1835.—

37*

438 CHEMICAL DUALITIES OF THE CUTICLE.

of cuticle has received an entirely new aspect, from recent
observations, and especially from those of Henle.* He has
shown that with very few exceptions, all the free surfaces of
the body — not only the skin which has its cuticular covering —
but those of the serous cavities, the mucous passages,! the
blood-vessels, and the ducts of the glands, are invested by a
membrane, composed of one, or more layers of primary cells,
forming a delicate cuticle or epithelium. The epidermis,
cuticle, or external covering of the skin, when examined with
a powerful microscope, is seen to be composed of several layers
of cells, which 'are the consequence of an uninterrupted process
of exudation which has place upon the corion or true skin.
This exudation, though unorganized, retains some vital proper-
ties, and is a cytablastema ; that is, a basis structure, or soil/
from which new growths or developments take place. These
new growths are cytoblasts, or cell germs ; that is, cells or
vesicles, at first globular, afterwards lenticular and opaque,
(each one surrounding a central nucleus), which possess within
themselves the inherent principles of growth.^ The more
recently produced cells, which of course are those in contact
with the corion, are like all young cells, spherical in their
figure ; they become flattened as they develop themselves
and approach the surface ; so that when examined on a sec-
tion, they are found to have undergone changes of form from
that of a globular cell, provided with a nucleus, to that of
a flat scale, in which no trace of a nucleus appears, and which
lay, one over another, like so many layers of tiles or pavement.
The innermost layers are soft and cellular; the outer ones
become dried on the surface from exposure to the air, and fall
off in squamae or scales. — §

* Allgera. Anat., p. 260.

f Vide Gen. Anat. of Serous and Mucous Membr. Vol. 2.

f The cell germs, here and in other parts of the body, bear a general rela-
tion to the size of the blood globules of the same individual. This is a remarka-
ble fact, and somewhat in favor of the views of Dr. Barry, who states that it is
the blood disks that are transformed into these cell germs. — Phil. Trans. Part
11. 1840.

§ Henle, makes three varieties of epithelium or cuticle, 1st. The pavement-
ed sqnamous or tesselated epithelium, above described, found on the skin, serous

THE NAILS. 439

The Nails.

The roots of the nails appear to originate in a fold of the
cutis vera, from the epidermis which lines the fold ; but "ihe
bodies of the nails adhere firmly to the cutis on which they lie,
and appear to cover it, in the place of the cuticle. The papillae
of those parts of the cutis which are covered by the nails are
very conspicuous when the nails are removed. It has been
supposed that there was no rete mucosum between the nails and
cutis ; but this opinion is probably erroneous, as the black pig-
ment is perceptible under the nails of some negroes.

The nails can be separated from the cutis by all those pro-
cesses which separate the cuticle from it. When this is effected,
they remain connected with the cuticle, which appears to be
continued into them ; and on this account, as well as their
insensibility, and their resemblance to the horny excrescences of
the cuticle, they are considered as appendages of it.

The root is opaque, and appears white. The body is trans-
parent, and in health shows the florid color of the cutis which it
covers ; but the color of this portion of the cutis depends upon
the state of the circulation ; and becomes livid when the blood
is disoxygenated, or when the circulation ceases there ; and this
color also appears through the nails.

The nails are unquestionably organized, although their ultimate
structure is not known. They appear to be composed of lamellae,
and these lamellae of fibres. They grow rapidly, and when
they are not pared or worn away, they sometimes acquire an
immense size.

As a remarkable instance of this, it is related, that a nail of
the great toe was sent from Turin to the Academy of Sciences
at Paris, which measured four inches and a half in length.

The growth seems to take place altogether at the roots.

The nails, when chemically examined, appear to consist of

membranes, the lining membrane of the mouth, pharynx, oesophagus, and the
vagina and cervix uteri. 2d. The cylinder epithelium, found in the remainder
of the alimentary canal, the ducts of the glands, and a great part of the genito-
urinary apparatus of the male. 3. The ciloary epithelium, found in the respira-
tory organs, the lachrymal passages, Eustachian and Fallopian tubes, etc.
Vide the account of these organs,

440 THE NAILS.

a modification of albumen ; and thus resemble cuticle and horn
in their composition.

— The growth of the nails, forwards, is entirely from a fold
of the cutis vera, at its root, called, though not with exact pro-

priety, the matrix of the nail, as seen
iri fig. 116. It grows also in thickness
%>m the upper surface of the skin,
upon which the nail rests. In the
formation of a new nail the la-
men which starts from the matrix,
receives successive layers from be-
neath, as it approaches the extremity, the deepest seated of
which is the shortest. In this way the nail gets its thickness and
strength, and occasionally, where the deposition of new matter,
goes on more rapidly under the body of the nail than at the
matrix, the body is thrown up into unsightly rugosities. Its
development is exactly similar to that of the horns and hoofs of
animals. The striated appearances of the nail, is said to be
owing to the papillary prominences below, being arranged in con-
centric plicae. The white semicircular line at the root, is
called the lunula.

— The nails are not exactly analogous in structure to the cuticle,
in the ordinary acceptation of the term — to that part which is
raised up under a blister. The proper cuticle is that thin coating
which is scraped away and worn off near the root, and which
otherwise would cover the surface. . The nails consist of the
proper cuticle, and tunica albuginea superficialis and the gem-
mules of Gaultier — leaving interposed between them and the
cutis vera, the tunica albuginea profunda which is insensible, and
explains why it is that a splinter, or the blade of a small pair
of scissors, in the operation for onychia, may be run along
close on the under surface of the nail, without the production
of much pain. According to Breschet, the nail is formed like
the other parts of the horny coat exterior to the cutis vera, by
the glands for the secretion of the mucous and coloring matter ;
the products of which would be mixed up together, coloring the
substance of the nail, as we know is the case in regard to the
horns and hoofs of animals. —

THE HAIRS. 441

The Hairs

Originate from bulbs which are situated at the bottom of
pores or cavities in the skin. These pores appear to be Imed
by a production of the cuticle, and the extremities of the bulbs
project beyond them into the cellular membrape. In some
cases, where the cuticle is separated after putrefaction, it seems
that these lining processes of the cuticle come away completely,
and bring the hairs and roots with them ; but in other cases,
the cuticle separates from the cutis, and leaves the hairs in their
natural situation.*

When viewed in a microscope, the bulb appears half trans-
parent, and whitish ; and of a softer consistence than the hair
itself. The extremity of it is remarkably flexible, and some-
times much darker than the rest of the bulb. The hair does
not appear to extend completely to the end of the bulb. Neither
blood-vessels nor nerves have been traced to these bulbs,
although it is probable they extend there ; for the operation
of extracting hair by the roots is generally very painful ; and
blood sometimes appears in the pore from which the hair is
extracted.

The body of the hair appears to be composed of smaller
fibres, enclosed in a membrane which often is imperfect at the
extremity ; in consequence of which the fibres often separate
from each other, or split.

Within the hair is diffused the substance upon which its
color depends : this does not appear to be essential to the
structure, as in the advance of life the hair is so generally
without it, while its structure continues unchanged, although it
becomes less flexible.

The color of the hair appears to have some connexion with

* Dr. Dom. Nardo, of Padua, asserts that he has succeeded frequently upon
himself, in transplanting a hair with its bulb, from one of the pores of the head
into one of the pores of the chest ; which is done by enlarging the latter pore
with a needle, introducing the bulb into it with exactness, and exciting a slight
inflammation around it by friction. The planted hair takes root, grows, arid in
process of time, undergoes the usual changes, — becomes gray, and is shed. —
Giorn delV ltd. —

442 BULBS OF THE HAIRS.

the color of the rete mucosum, as it is so generally black
when the rete mucosum is dark colored.

The sudden change of color in consequence of fright or
grief, is a very rare occurrence indeed ; but Bichat relates
an instance which came under his observation, in which the
hair became perfectly white in one night, in consequence of
grief.

— The substance of the hair is of a corneous nature like the
epidermis. Each hair consists of two parts, a bulb or follicle,
and a stalk or hair proper.

— The follicle is ovoidal, and consists of two membranes. The
exterior is white, firm, and continuous with the cutis vera ; the
interior, which is thin, soft and reddish, appears to be continuous
with the corneous layers.

— The cavity of the follicle is filled up at the bottom with a
conical papilla, into which, according to Beclard, the nerves
and blood-vessels may be seen running below. Rudolphi and
Andral, have traced nerves into the whiskers of the seal ;
Shaw has done the same, and discovered that they were
branches of the fifth pair. The root of the hair possesses a coni-
cal cavity, in which is lodged the point of the papilla which
appears to secrete the matter of the hair, and cause its growth,
by the continuous deposition of new matter at its root, as takes
place in regard to the nails of man, and the horns of animals ;
this deposit of new matter in the fluid state, has been seen
between the hair and papilla. It is sometimes secreted in pro-
fusion, especially in the head ; and has appeared to me, by over-
flowing from the follicles, and drying in the form of scales, to
be the source of the dandriff.

— The epidermis is reflected from the mouth of the follicle, and
lost upon the surface of the hair.

— The hair, when examined with the microscope, appears to
be covered externally with small scales, and to be hollow inter-
nally. The latter, however, is as regards the human hair, an
optical illusion, as it is merely loose and porous or pith-like in
its central part. The stalks of hairs have neither vessels nor
nerves in their structure, and anatomists no longer admit

STRUCTURE OF THE HAIRS. 443

a fluid in their interior described by Bichat and others as the
marrow.*

— Around the orifices of the follicle, and in the substance o£/its
neck according to Gaultier, we find a number of minute
sebaceous glands, that secrete an unctuous fluid, which
imbues the hair and preserves its softness and pliability. The
hairs are hygrometrical, and increase in length and thickness
when exposed to humidity ; and are shortened again by dry heat.
— From the changes which take place in regard to the color
of the hair, there is reason to believe, that it is traversed by
some fluid. This passes along the hair by imbibition, from
the root upwards, in consequence of its hygrometrical nature,
passing up through the spongy or cellular tissue of which the
body of the hair appears to be formed. This fluid is
derived from the surface of the skin forming the papilla, and
is analogous to the fluid of the rete mucosum, and corresponds
more or less in color with that of the skin and iris.
— The hairs vary much in size, but appear all to be constructed
on the same plan. They have different names in different parts
of the body, as beard, whiskers, eyelashes, &c. The minute
hairs generally spread over the body, are called down or
duvette, and those which cover the scalp, in man, have particu-
larly appropriated to them the term of hair. In the white or
Caucasian variety of the human race, the hairs of the head are
very numerous, fine, long, and vary in color from white to
black : in the Mongolian they are straight, black and short :
in the Negro, black, fine, thick and crisped : in the Indian,
black, straight, fine and thick: and in the Malay, thick and
frizzled.

— Their size and number vary in regard to their color.
Withoff, has calculated that in a quarter of an inch square of
skin there are one hundred and forty-seven black hairs, one
hundred and sixty-two chestnut, and one hundred and eighty-
two, blond.
— The hairs are composed chemically, agreeably to Vauquelin,

4

* Note to Bichat, 4th edit. Paris. —

444 CHEMICAL COMPOSITION OF THE HAIRS.

chiefly of animal matter, of some concrete white, and some
black oily matter; iron, oxide of manganese, phosphate and
carbonate of lime, silex and sulphur. The change of color to
gray, is said to be owing to a preponderance in the formation
of the white oily substance, and the development of some
phosphate of magnesia.* The shape of the hairs vary in differ-
ent parts.

— From the large size of the nerves which enter the papilla?,
to which the hairs are attached, they become in many animals
delicate instruments of touch. The formation of the hair
depends upon the follicle ; while this remains healthy, though
the hair should be removed by its roots, it will again be repro-
duced.

— Boucheron in a recent work on the hair, says that in baldness
the bulbs are often only partially atrophied, a circumstance
which does not render hopeless the idea of their recovering
their original functions, and re-secreting the horny matter
which forms the hair, under the influence of certain stimuli.
— Round the bulbs of the larger hairs, are found some smaller
ones, which, as seen in extraction of the former in some cases
of tinea capitis, are sometimes developed to an unusual extent.
— It has also been frequently observed, that in many women
the almost imperceptible down of the face presents, after the
fortieth or fiftieth year of age, a great increase of development.
The bulbs of the hairs are obliquely and confusedly
implanted in the dermis — hence when one straggling white
hair is extracted from the head, the neighboring ones speedily
whiten in their turn from the disturbance and injury which their
bulbs have suffered.

— There are many hairs, which are developed so feebly that
they do not pass the epidermis, but roll and curve themselves
under it. From accidental circumstances the energy of the
bulbs of these hairs is sometimes so increased, that skin which
had been previously smooth, becomes hairy. Boucheron, attri-
butes the color of the hair to a peculiar animal oil, secreted

* C. P. Ollivier.

CHEMICAL COMPOSITION OF THE HAIRS. 445

by the bulbs, and varying consequently in its properties in
different individuals. It is to a change in the color of this oily
matter, arising from a variety of causes, which enfeeble' the
general system, as grief, intense study, &c., that is attributed the
whitening of the hair. —

The SKIN, constructed as above described, answers a fourfold purpose in the
animal economy. It is the organ of touch. It covers and protects the whole
structure. It is the outlet for a large proportion of the insensible perspira-
tion, and it performs to a certain extent absorption.

Many facts have been noticed by practitioners of medicine, which proves that
it has a connexion with the lungs and stomach, which is not yet explained by
anatomy.

As one of these, an effect of the urticaria or nettle-rash may be mentioned.
This eruption sometimes relieves completely the spasmodic croup; and in
other cases, nausea and vomiting.

Some children, when affected with this species of croup, are relieved by rubbing
the skin with harsh woolen cloth.

In some places, the urticaria and the affection of respiration are so much
regarded as symptoms of the same disease, that the term hives is used as the
name for each of them.

38

PART V.

OF THE NOSE, THE MOUTH, AND THE THROAT.
CHAPTER XII.

OF THE NOSE.

THE prominent part of the face, to which the word nose is
exclusively applied in ordinary language, is the anterior covering
of two cavities which contain the organ of smelling.

These cavities are formed principally by the upper maxillary
and palate bones ; and, therefore, to acquire a complete idea of
them, it is necessary to study these bones, as well as the os
ethmoides, the vomer, and the ossa spongiosa inferiora, which
are likewise concerned in their formation.

In addition to the description of these bones, in the account
of the bones of the head, it will be useful to study the descrip-
tion of the cavities of the nose which follows it, (see page 122.)

After thus acquiring a knowledge of the bony structure, the
student will be prepared for a description of the softer parts.

Of the External Nose.

The superior part of the nose is formed by the ossa nasi, and
the nasal processes of the upper maxillary bones, which have
been already described, (see pages 86-89) ; but the inferior
part, which is composed principally of cartilages, is much more
complex in its structure.

The orifice, formed by the upper maxillary and nasal bones,
is divided by a cartilaginous plate, which is the anterior and
inferior part of the septum, or partition between the two cavi-
ties of the nose. The anterior edge of this plate projects beyond
the orifice in the bones, and continues in the direction of the

OF THE NOSE.

447

suture between the ossa nasi. This edge forms an angle with
the lower edge of the same cartilage, which continues from it
in a horizontal direction, until it reaches the lower part df the
orifice of the nose, at the junction of the palatine processes of
the upper maxillary bones ; where a bony prominence is
formed, to which it is firmly united. The upper part of the
anterior edge of this cartilage, which is in contact with the ossa
nasi, is flat, and, is continued into two lateral portions that are
extended from it one on each side, and form a part of the nose :
these lateral portions are sometimes spoken of as distinct carti-
lages, (superior lateral?) but they are really continuations of
the middle portion or septum.

Below the lower edge of these late-
ral portions are situated the fibro carti-
lages which form the orifices of the
nose, or the nostrils. Of these, there is
one of considerable size, (inferior late-
ral,) and several small fragments, on
each side of the septum. Each of the
larger cartilages forms a portion of an
oval ring, which is placed obliquely on
the -side of the septum : so that the
extremity of the oval points downward
and forward, while the middle part of
the oval is directed upwards and back-
wards. The sides of this cartilage are
flat, and unequal irf breadth. The narrowest side is internal,
and projects lower down than the cartilaginous septum ; so that
it is applied to its fellow of the other nostril. The external
side is broader, and continues backward and upward to a con-
siderable distance.

* —a, b, Ossa nasi, which show above, the serrated surface by which they
are united to the os fronds, c, d, Superior lateral cartilage, e, Vertical carti-
laginous septum of the nose. /, /, Sesamoid cartilages, filling up part of the
vacuity here. gt I, Oval or inferior lateral cartilages, or cartilages of the alse
nasi ; below they are thin and curved so as to form the arch of the anterior
nares. h, i, k, Small square cartilages appended to the alae nasi and circum-
scribing the outer and back part of the nostrils, m, n, o, Same parts of the
right side.

448 OF THE NOSE.

The upper and posterior part of this oval ring is deficient ;
but the remainder of the nostril consists of several small pieces
of cartilage, (cartilages carres,) which are fixed in a ligamen-
tous membrane that is connected by each of its extremities to the
oval cartilage, and thus completes the orifice.

The anterior parts of the oval cartilage form the point of the
nose ; and the ligamentous portions, the alae or lateral parts of
the nostrils.

When the external integuments and muscles are removed
from the lower portion of the nose, so that the internal mem-
brane and these cartilages only remain, the internal membrane
will be found attached to the whole bony margin of each orifice,
and to each side of the whole anterior edge of the middle
cartilage, which projects beyond the bones. This membrane is
afterwards continued so as to line the oval cartilages and the
elastic membrane of the ala nasi, to the margin of the orifice of
the nostril.

The internal portions of the oval cartilages being situated
without the septum, and applied to each other, they form the
external edge of the partition between the nostrils, or the
columna nasi ; which is very movable upon the edge of the
middle cartilage.

The orifices of the nostrils, thus constructed, are dilated by
that portion of the muscle, called Levator Labii Superioris
Alceque Nasi, which is inserted into the alae nasi.

They are drawn down by the depressor labii superioris alsque
nasi. They are pressed against the septum and the nose by
the muscle called Compressor Narisy which has however an
opposite effect when its upper extremity is drawn upwards by
those fibres of the occipito frontalis, which descend upon the
nose, and are in contact with it.

The end of the nose is also occasionally drawn down, by
some muscular fibres which descend from it, on the septum of
the nose, to the orbicularis oris : they are considered as a por-
tion of this muscle by many anatomists, but were described by
Albinus as a separate muscle, and called Nasalis Labii

OF THE CAVITIES OF THE NOSE. 449

When inspiration takes place with great force, the alae nasi
would be pressed against the septum, if they were not drawn
out and dilated by some of the muscles above mentioned.

Of the Cavities of the Nose.

To the description of the osseous parts of the nasal cavities
in page 89, it ought now to be added, that the vacuity in the
anterior part of the osseous septum is filled up by a cartilaginous
plate, connected with the nasal lamella of the ethmoid bone
above, and with the vomer below. This plate sends off those
lateral portions already described, which form the cartilaginous
part of the bridge of the nose.

It should also be observed that at the back parts of these
cavities are two orifices called the Posterior Nares, (see
fig. 118, p. 454,) which are formed by the palate bones, the
vomer, and the body of the sphenoidal bone, and are somewhat
oval.

The nasal cavities, thus constructed, are lined by a peculiar
membrane, which is called pituitary from its secretion of mucus,
or Schneiderian after the anatomist who described it with ac-
curacy.*

This membrane is very thick and strong, and abounds with
so many blood-vessels, that in the living subject it is of a red
color. It adheres to the bones and septum of the nose like
the periosteum, but separates from them more easily. The
surface which adheres to the bones has some resemblance to
periosteum, while the other surface is soft, spongy, and rather
villous. Bichat seems to have considered this membrane as
formed of two lamina, viz. periosteum, and the proper mucous
membrane ; but he adds, that it is almost impossible to separate
them.

It has been supposed that many distinct glandular bodies
were to be seen in the structure of this membrane by examin-
ing the surface next to the bones ;f but this opinion is adopted

* Conrad Schneider, a German professor, in a large work, "De Catarrhis,"
published about 1660.
f See Winslow, Section X. No. 337.

38*

450 SCHNEIDERIAN MEMBRANE.

by very few of the anatomists of the present day. The texture
of the membrane appears to be uniform; and on its surface are
a great number of follicles of various sizes, from which flows
the mucus of the nose.

These follicles appear like pits, made by pushing a pin ob-
liquely into a surface which retains the form of the impression.
They can be seen very distinctly with a common magnifying
glass when the membrane is immersed in water, both on the
septum and on the opposite surface. They are scattered over
the membrane without order or regularity, except that in a few
places they occur so as to form lines of various lengths, from
half an inch to an inch. The largest of them are in the lower
parts of the cavities.

— The surface of this membrane when examined with the mi-
croscope, is found to be furnished with the ciliary epithelium,
consisting of minute projections or columns, thickly set with
fine cilia or fringes, which have a peculiar vibratile motion of
their own for carrying on fluids, not well understood. —

It may be presumed that the secretion of mucus is effected
here by vessels which are mere continuations of arteries spread
upon a surface analogous to the exhalents, and not convoluted
in circumscribed masses, as in the case of ordinary glands.

The arteries of this membrane are derived from various
sources : the most important of them is the nasal branch of the
internal maxillary, which passes into the nose through the
spheno-palatine foramen, and is therefore called the Spheno-
palatine Artery. It divides into several twigs, which are spent
upon the different parts of the surface of the nasal cavities.
Two of them are generally found on the septum of the nose :
one, which is small, passes forwards near the middle ; the other,
which is much larger, is near the lower part of it.

Two small arteries, called the anterior and posterior eth-
moidals, which are branches of the ophthalmic, enter the nose
by foramina of .the cribriform plate of the ethmoidal bone.
These arteries pass from the orbit to the cavity of the cranium,
and then through the cribriform plate to the nose. In addition
to these, there are some small arteries derived from the infra-

OLFACTORY NERVES. 451

orbital, the alveolar and the palatine, which extend to the
Schneiderian membrane; but they are not of much importance.

The veins of the nose correspond with the arteries. Tliose
which accompany the ethmoidal arteries open into the ocular
vein of the orbit, which terminates in the cavernous sinuses of
the head. The other veins ultimately terminate in the external
jugulars.

The nerves of the nose form an important part of the struc-
ture ; they are derived from several sources ; but the most
important branches are those of the olfactory.

The olfactory nerves form oblong bulbs, which lie on each
side of the crista gilli, on the depressed portions of the cribri-
form plate of the ethmoid bone, within the dura mater. These
bulbs are of a soft consistence, and resemble the cortical part of
the brain mixed with streaks of medullary matter. They send
off numerous filaments, which pass through the foramina of
the ethmoid bone, and receive a coat from the dura mater as
they pass through it.

These filaments are so arranged that they form two rows,
one running near to the septum, and the other to the surface of
the cellular part of the ethmoid bone, and the os turbinatum :
and in addition to these are some intermediate filaments.

When the Schneiderian membrane is peeled from the bones to
which it is attached, these nervous filaments are seen passing
from the foramina of the ethmoid bone to the attached surfaces :
one row passing upon that which covered the septum, and the
other to that of the opposite side ; while the intermediate fila-
ments take an anterior direction, but unite to the membrane as
soon as they come in contact with it.\^~

All of these can be traced downwards on the aforesaid surfaces
of the membrane for a considerable distance, when they grad-
ually sink into the substance of the membrane, and most pro-
bably terminate on the internal villous surface ; but they have
not been traced to their ultimate termination. They ramify so
that the branches form very acute angles with each other. On
the septum the different branches are arranged so as to form

452 SPHENO-PALATINE AND OTHER NERVES OF THE NOSE.

brushes, which lie in contact with each other. On the opposite
sides, the different ramifications unite, so as to form a plexus.

Dr. Soemmering has published some very elegant engravings
of the nose, representing one of his dissections, which appears
to have been uncommonly minute and successful.* These
represent the ramifications as becoming more expanded and
delicate in the progress towards their terminations, and as
observing a tortuous course, with very short meandering
flexures.

It is to be observed that the ramifications of the olfactory
nerve, thus arranged, do not extend to the bottom of the cavity.
On the external side, they are not traced lower than the lower
edge of the etbmoid, or of the superior spongy bone: and on
the septum, they do not extend to the bottom, although they
are lower than the opposite side. On the parts of the mem-
brane not occupied by the branches of the olfactory nerves,
several other nerves can be traced. The nasal twig of the
ophthalmic branch of the fifth pair, after passing from the orbit
into the cavity of the cranium, proceeds to the nasal cavity on
each side by a foramen of the cribriform plate ; and after send-
ing off some fibrillae, descends upon the anterior part of the
septum to the point of the nose. The spheno-palatine nerve,
which is derived from the second branch of the fifth pair, and
enters the nose by the spheno-palatine foramen, is spread upon
the lower part of the septum and of the opposite side of the
nose also, and transmits a branch through a canal in the fora-
men incisivum to the mouth. Several small branches also pass
to the nose from the palatine and other nerves; but those
already mentioned are the most important.

A question has been proposed, whether the olfactory nerve
is exclusively concerned in the function of smelling, or whether
the other nerves above mentioned are also concerned in it. It
seems probable that this function is exclusively performed by
the olfactory nerve, and that the other nerves are like the
ophthalmic branch of the fifth pair, with respect to the optic

* They are entitled, Icones Organorum Humanorum Olfactus.

EXTENT OF THE SCHNE1DER1AN MEMBRANE. 453

nerve. In proof of this, it is asserted that the sense of smelling
has entirely ceased in some cases, where the sensibility to
mechanical irritation of every kind has remained unchanged.
If the olfactory nerve alone is concerned in the function of
smelling it follows, that this function must be confined to the

O' '

upper parts of the nasal cavities ; but it ought to be remem-
bered, that the structure of the Schneiderian membrane, in the
lower parts of these cavities, appears exactly like that which
is above.

The surface of the nasal cavities and their septum, when
covered with the Schneiderian membrane, correspond with the
osseous surface formerly described. The membrane covers the
bones and cartilage of the septum, so as to make one uniform
regular surface. From the upper part of the septum, it is con-
tinued to the under side of the cribriform plate of the ethmoid,
and lines it ; the filaments of the olfactory nerve passing through
the foramina of that bone into the fibrous surface of the mem-
brane. It is continued from the septum, and from the cribri-
form plate, to the internal surface of the external nose, and
lines it. It is also continued backwards to the anterior surface
of the body of the sphenoidal bone ; and, passing through the
foramina or openings of the sphenoidal cells, it lines these
cavities completely ; but in these, as well as the other cavities,
its structure appears somewhat changed ; it becomes thinner
and less vascular.

At the above mentioned foramina, in some subjects, it forms
a plate or fold, which diminishes the aperture considerably.

From the upper surface of the nasal cavities, the membrane
is continued downwards over the surface opposite to the sep-
tum. On the upper flat surfaces of the cellular portions of the
ethmoid, it forms a smooth uniform surface. After passing over
the first turbinated bone, or that called after Morgagni, it is
reflected into the groove, or upper meatus immediately within
and under it ; the fold formed by the membrane, as it is reflect-
ed into the meatus, is rather larger than the bone : and the
edge of the fold therefore extends lower down than the edge
of the bone, and partly covers the meatus like a flap, consisting

454

EXTENT OF THE SCHNEIDERIAN MEMBRANE.

only of the double membrane. This fold generally continues
backwards as far as the spheno-maxillary foramen, which it
closes ; the periosteum, exterior to the foramen, passing through
H, and blending itself with the fibrous surface of the Schneide-
Fig. 118.*

* Fig. 118 — is a vertical section, exhibiting a profile view from the inside of
the cavities of the nostrils, mouth, and pharynx, a, The nose, b, Upper lip,
situated in front of the palatine arch, which runs horizontally backwards, and
divides the cavity of the mouth from the nasal fossae, c, The tongue, the base
of which is attached to the os hyoides d. e, The larynx, suspended from the os
hyoides, by the thyreo-hoid ligaments which are seen intervening ; it opens
backwards towards the pharynx. /, Trachea, g, Cuneiform process of the
occipital bone, united to the body of the sphenoid, and to which is chiefly
suspended the pharynx h, which is laid open (in order to show its shape and
position) by the removal of its right half, and is seen terminating below opposite
the cricoid cartilage in the ossophagus. i, Commencement of the resophagus.
7;, Section of the velum pendulum palatae, the lower point of which constitutes
the uvula; above this is seen the opening of the posterior nares, 7, into the
top part of the cavity of the pharynx ; below this are seen the two half arches
of the palate, o, Posterior half arch, r, Anterior half arch, the space or
cavity between these occupied by the tonsil gland or amygdala p. 7, Sublingual

DISTRIBUTION OF THE SCHNEIDERIAN MEMBRANE. 455

nan membrane within. Here the spheno-palatine nerves and
arteries join the membrane. Below this meatus, it extends
over the middle, (formerly called the upper,) turbinated bope,
and is reflected or folded inwards on the under side of this bone,
and continued into the middle meatus below it. In the middle
meatus, which is partly covered by the last mentioned turbina-
ted bone, there are two foramina ; one communicating with the
maxillary sinus, and the other with the anterior cells of the
ethmoid and the frontal sinuses. The aperture into the maxil-
lary sinuses is much less in the recent head, in which the
Schneiderian membrane lines the nose, than it is in the bare
bones. A portion of the aperture in the bones is closed by the
Schneiderian membrane, which is extended over it : the re-
mainder of the aperture is unclosed ; and through this foramen,
the membrane is reflected so as to line the whole cavity. As a
portion of the foramen is covered by the 'membrane, and this
portion, as well as the other parts of the cavity, is lined by the
membrane, it is obvious that at the place where the membrane
is extended over the foramen in the bone, it must be doubled ;
or, in other words, a part of the aperture of the maxillary sinus
is closed by a fold of the Schneiderian membrane.*

This aperture varies in size in different subjects, and is often
equal in diameter to a common quill. It is situated in the

gland, placed under the tongue, and communicating with the mouth by a small
duct, (ductus Bartholinus :) many small ducts from this gland, open into the
duct of the gland below, m, Sub- maxillary gland, situated below and behind
the preceding gland, n, Thyroid gland, s, Vertical section of the border of
the cervical vertebrae, to which the pharynx is attached by cellular tissue.
tj Spinal canal, u, Section of spinous processes and muscles of the neck.
v, Left nostril. TV, Bony palate, z, Trumpet-shaped orifice of the Eustachian
tube, y, Inferior turbinated bone, covered by the Schneiderian membrane.
z, Middle turbinated bone. 1, Superior turbinated bone, both covered with the
same membrane. 2, Superior meatus. 3, Middle meatus. 4, Inferior meatus.
5, Place of opening of the ductus ad nasum. 6, Frontal sinuses. 7, The
posterior nares. 8, Sphenoidal cell in the body of the sphenoid bone, showing
the orifice below, by which it communicates with the top of the pharynx ; above
is seen the sella turcica of the sphenoid bone.

* In the mucous membrane lining the cavities of the maxillary, sphenoid
and ethmoid bones, no one has yet detected any mucous follicles. The pouch
formed by the reflection of the membrane, seems itself to constitute a large
follicle, from which mucus is abundantly secreted. — r.

456 OBSERVATIONS RESPECTING THE NOSE.

middle of the meatus, and is covered by the middle turbinatedv
bone immediately above it, — a prominence of the cellular
structure of the ethmoid bone, which has a curved or semicir-
cular figure. Near this prominence, in the same meatus, a
groove terminates, which leads from the anterior ethmoid cells
and the frontal sinuses.

From the middle meati^s, the membrane proceeds over, the
inferior turbinated bone, and is reflected round and under it
into the lower meatus. It appears rather larger than the bone
which it covers ; and therefore the lower edge of the bone does
not extend so low as the lower edge of the membrane, which
of course is like a fold or plait. The membrane then continues
and lines the lower meatus : here it appears less full than it is
in the turbinated bone. In this meatus, near to its anterior
end, is the lower orifice of the lachrymal duct ; this is simply
lined by the Schneiderian membrane, which is continued into
it, and forms no plaits or folds that effect the orifice.

Orifice of the Eustachian Tube.

Immediately behind each of the nasal cavities, on the exter-
nal side, is the orifice of the Eustachian Tube. It has an oval
form, and is large enough to admit a very large quill. Its posi-
tion is oblique: the upper extremity being anterior to the other
parts of the aperture, and on a^ line with the middle meatus,
while the centre is benind the inferior turbinated bone. The
lower part of the oval is deficient. This tube is formed poste-
riorly by a cartilaginous plate. It is lined by the membrane
continued from the nose.

The cavities of the nose answer a twofold purpose in the animal economy ;
they afford a surface for the expansion of the olfactory nerves, and a passage
for the external air to the windpipe, in respiration.

The function of smelling appears to be dependent, to a certain degree, upon
respiration. It has been asserted that unless the air passes in a stream
through the nose, as in respiration, the perception of odor does not take
place ; that in persons who breathe through wounds and apertures in the
windpipe, the function of smelling is not performed. It is rather in confir-
mation of this proposition, that most persons, when they wish to have an
accurate perception of any odor, draw in air rapidly through the nose.

Although the ultimate termination of the olfactory nerves cannot be demon-
strated like those of the optic and auditory nerves, it is probable, from the

USES OF THE SINUSES OF THE NOSE. 457

appearance of the fibres, while they are distinguishable, that they are finally
arranged with great delicacy. It is certain that the impressions from whence
we derive the perceptions of many odors, must be very slight, as some
odorous bodies will impregnate the air of a large chamber for a great length
of time, without losing any sensible weight.

With respect to delicacy of structure and sensibility, it is probable that the nose
holds a middle rank between the eye or ear, and the tongue : and on this
account the mucus is necessary as a covering and defence of its surface.

It has been ascertained, by the investigations of chemists, that this mucus con-
tains the same ingredients as the tears already described, namely, animal
mucus and water ; and muriate of soda, and soda uncombined j phosphate of
lime, and phosphate of soda.

The animal mucus, which is a most important ingredient in the composition,
resembles the mucilage formed by some of the vegetable gums in several
particulars ; and differs from them in others.

The mucus of the nose, if it remain there long after it is secreted, becomes
much more viscid in consistence, and changes from a whitish color to one
which partakes more or less of the yellow. It is probable that an incipient
putrefaction may occasion these changes in it.

The use of the frontal, maxillary and other sinuses, communicating with the
nose, has been the subject of some inquiry. As there can be no stream of
air through them, and as the membrane lining them is neither so thick, villous
nor flexible as that lining the nose, it may be concluded, a priori, that they
are not concerned in the function of smelling. This opinion is strengthened
by the fact, that very young children, in whom these sinuses scarcely exist,
enjoy the sense of smelling in perfection. The following fact is also in sup-
port of it. The celebrated Desault attended a patient, in whom one of the
frontal sinuses was laid open by the destruction of the bone which covered it
anteriorly. This patient was able to breathe a short time through the sinus
when the mouth and nose were closed : at the request of Desault he breathed
in this manner when a cup of some aromatic liquor was held near the open-
ing of the sinus, and had not the least perception of odor. This experiment
was repeated several times.

Many physiologists believe that these sinuses have an effect in modulating the

39

458 OF THE MOUTH.

CHAPTER XIII.

OF THE MOUTH.

THE general cavity of the mouth is formed anteriorly and
laterally by the connexion of the lips and cheeks to the upper
and lower jaws ; so that the teeth and the alveoli of both jaws
may be considered as within the cavity. Above, it is bounded
principally by the palatine processes of the upper maxillary
and palate bones, and the soft palate, which continues back-
ward from them in the same direction.

Below, the cavity is completed by several muscles, which
proceed from almost the whole internal circumference of the
lower jaw, and, by their connexions with each other, with the
tongue and the os hyoides, form a floor or bottom to it. The
tongue is particularly connected to this surface, and may be
considered as resting upon and supported by it.

To acquire an idea of the parietes of this cavity, after
studying the upper and lower maxillary bones, the orbicularis
oris and the muscles connected with it, especially the buccina-
tor, ought to be examined ; and also the diagastricus, the
mylo-hyoideus, genio-hyoideus, and genio-hyoglossus. By
this it will appear that the lips and cheeks, and the basis or
floor of the mouth, are formed in a great measure by muscles.
Upon the internal surface of these muscles, a portion of cellular
and adipose substance is arranged, as well as glandular bodies
of different sizes ; and to these is attached the membrane which
lines the inside of the mouth.

This membrane passes from the skin of the face to the lips,
and the inside of the mouth ; and, although it is really a con-
tinuation of the skin, there is so great a change of structure that
it ought to be considered as a different membrane. At the
orifice of the lips it is extremely thin, and so vascular, that it

INTERNAL SURFACE OF THE MOUTH. GUMS. 459

produces the fine florid color which appears there in health.
It is covered by a cuticle, called by some anatomists, Epithe-
lium, which has a proportionate degree of delicacy, and carf be
separated like the cuticle in other parts. When this cuticle is
separated, the lips and the membrane of the mouth appear to
be covered with very fine villi, which are particularly apparent
in some preparations of the lips after injection and maceration.*

Under this membrane are many small glandular bodies of a
roundish form, called glandulae labiales, whose excretory ducts
pass through it to the inner surface of the mouth, for the pur-
pose of lubrifying it with their secretion, which is mingled with
the saliva.

The membrane which lines the inside of the lips and cheeks,
is somewhat different from that which forms the surface of the
orifice of the mouth : it is not so florid ; the blood-vessels in
its texture are larger, and not so numerous. This change,
however, takes place very gradually, in the progress of the
membrane, from the orifice of the lips to the back part of the
cheeks. Glandular bodies, like those of the lips, are situated
immediately exterior to this membrane of the cheeks, between
it and the muscles : their ducts open on its surface. These
glands are called Buccales.

This lining membrane is continued from the internal surface
of the lips and cheeks to the alveolar portions of the upper and
lower jaws, which are in the cavity of the mouth, and covers
them, adhering firmly to the periosteum.

The teeth appear to have passed through apertures in this
membrane, and are surrounded by it closely at their respective
necks.

The portion of membrane, which thus invests the jaws, con-
stitutes the gums ; which have now acquired a texture very
different from that of the membrane from which they were
continued. They are extremely firm and dense, and very
vascular. It is probable that their ultimate structure is not
perfectly understood.

* Ruysch had a fine preparation of this structure. See Thesaurus VII. Tab.
III. Fig. 5.

460 MEMBRANE LINING THE HARD OR BONY PALATE.

In the disease called scurvy, they tumefy and lose the firm-
ness of their texture : they acquire a livid color, and are much
disposed to hemorrhage.

From the alveoli of the upper jaw, the lining membrane is
continued upon the palatine processes of the upper maxillary
and palate bones, or the roof of the mouth.

The membrane of the palate is not quite so firm as" that of
the gums, and is also less florid : it adheres firmly to the peri-
osteum, and thus is closely fixed to the bones. There is gene-
rally a ridge on its surface, immediately under the suture be-
tween the two upper maxillary bones ; and some transverse
ridges are also to be seen upon it. On the internal surface of
this membrane, are small glandular bodies, whose ducts open on
the surface of the palate.

It is asserted, that this membrane has a limited degree of that
sensibility which is essential to the functions of tasting ; and
that if certain sapid substances are carefully applied to it, their
respective tastes will be perceived, although they have not been
in contact with the tongue.

The membrane is continued from the bones above mentioned
to the soft palate, or velum pendulum palati, which is situated
immediately behind them. This soft palate may be considered
as a continuation of the partition between the nose and mouth ;
it is attached to the posterior edge of the palatine processes of
the ossa palati, and to the pterygoid processes of the sphenoidal
bone. Its interior structure is muscular. The upper surface is
covered by the membrane of the nose, the lower surface by the
membrane which lines the mouth.

The muscles, which contribute to the composition of this
structure, are the circumflexi and the levatores palatii above,
and the constrictores isthmi faucium and palato-pharyngei below.
(See pages 318, 319.) Thus composed, the soft palate con-
stitutes the back part of the partition between the nose and
mouth. When viewed from before, with the mouth open, it
presents towards the tongue an arched surface, which continues
downwards on each side, until it comes nearly in contact with
the edges of that organ. On each of the lateral parts of this

SOFT PALATE. UVULA. 461

arch, are two pillars, or rather prominent ridges, which project
into the mouth. These ridges are at some distance from each
other below, and approach much nearer above, so that *hey
include a triangular space. They are called the lateral half
arches of the palate, (see fig. 118, p. 455.) Each of them is
formed by a plate or fold of the lining membrane of the mouth,
and contains one of the two last mentioned muscles ; the anterior,
the constrictor isthmii faucium ; the posterior, the palato-
pharyngeus. These muscles, of course, draw the palate down
toward the tongue when they contract.

From the centre of the arch, near its posterior edge, is sus-
pended the uvula, a conical body, which varies in length from
less than half an inch, to rather more than one inch. It is
connected by its basis to the palate; but its apex is loose and
pendulous. This body is covered by the lining membrane of
the mouth. It contains many small glands, and a muscle also,
the azygos uvulae, which arises from the posterior edge of the
ossa palati, at the suture which connects them to each other,
and, passing posteriorly upon the soft palate, extends from the
basis to the apex of the uvula, into which it is inserted. By
the action of this muscle, the length of the uvula can be very
much diminished : and when its contraction ceases, that body is
elongated.*

The pendulous part of the uvula can also be moved, in certain
cases, to either side.

It is commonly supposed, that the principal use of this little
organ is to modulate the voice ; but there are good reasons for
believing, that it has another object. It was remarked by
Fallopius, (and the observation has been confirmed by many
surgeons since his time,) that the uvula may be removed com-
pletely without occasioning any alteration of the voice, or any
difficulty of deglutition, if the soft palate be left entire.

The soft palate is so flexible, that it yields to the actions of
the levatores palati, which draw it up so as to close the posterior
nares completely.

* A careful dissection, shows two of these muscles. — p.
39*

462 THE TONGUE.

It also yields to the circumflexi or tensores, which stretch it so
as to do away its arched appearance.

It is therefore very properly called the Palatum Molle, or
soft palate. It is also frequently called the Velum Pendulum
Palati, from the position which it assumes.

The Tongue,

which is a very important part of this structure, is retained in
its position and connected with the parts adjoining it, by the
following arrangements.

The os hyoides, which, as its name imports, resembles the
Greek letter v, or half an oval, is situated rather below the
angles of the lower jaw, in the middle of the upper part of the
neck. It is retained in its position by the sterno-hyoidei
muscles, which connect it to the upper part of the sternum, by
the coraco, or omo-hyoidei, which pass to it obliquely from the
scapula ; by the thyro-hyoidei, which pass to it directly
upward from the thyroid cartilage, all of which connect it to
parts below. To these should be added the stylo-hyoidei, which
pass to it obliquely from behind and rather from above : the
mylo-hyoidei, which come rather anteriorly from the lateral
parts of the lower jaw; and the genio-hyoidei, which arises
from a situation directly anterior and superior to the chin.
When these muscles are at rest, the situation of the os hyoides
is, as above described, below the angles of the lower jaw :
when those, in one particular direction act, while the others
are passive, the bone may be moved upwards or downwards,
backwards or forwards, or to either side. This bone may be
considered as the basis of the tongue ; for the posterior extrem-
ity of that organ is attached to it, and of course the move-
ments of the bone must have an immediate effect upon those of
the tongue.

The tongue is a flat body of an oval figure, but subject to
considerable changes of form.

The posterior extremity, connected to the os hyoides, is com-
monly called its base ; the anterior extremity, which, when the
tongue is quiescent, is rather more acute, is called its apex.

The lower surface of the tongue is connected with a number

STRUCTURE OF THE TONGUE. 463

of muscles, which are continued into its substance. This con-
nexion is such, that the edges of the tongue are perfectly free
and unconnected ; and so is the anterior extremity for a con-
siderable distance from the apex towards the base.

The substance of the tongue consists principally- of muscu-
lar fibres intermixed with a delicate adipose substance. It is
connected to the os hyoides by the hyo-glossus muscle, and also
by some other muscular fibres, as well as by a dense mem-
branous substance, which appears to perform the part of a
ligament. This connexion is also strengthened by the con-
tinuance of the integuments from the tongue to the epiglottis
cartilage, to be hereafter described ; for that cartilage is attached
by ligaments to the os hyoides.

The tongue is thin at its commencement at the os hyoides ;
but it soon increases in thickness. The muscular fibres in its
composition have been considered as intrinsic, or belonging
wholly to its internal structure ; and extrinsic, or existing in
part outside of this structure. The lingualis muscles are
intrinsic (see page 316) : they are situated near the under sur-
face of the tongue, one on each side, separated from each other
by the genio-hyo-glossi muscles, and extending from the basis
of the tongue to its apex. These muscles can be easily traced as
above described : but there are also many fibres in the structure
of the tongue, which seem to pass in every direction, and of
course are different from those of the linguales muscles. To
these two sets of fibres are owing many of the immensely
varied motions of the different parts of the tongue.

— According to Gerdy, (whose researches on this subject
have been approved by Ribes and Breschet,) the structure of
the tongue consists of the mucous membrane forming its outer
coat, of a peculiar yellow lingual tissue ' which forms the liga-
ment by which it is attached to the os hyoides and is extended
along the middle line of the tongue to form a sort of raphe for
the attachment of the transverse muscular fibres, and of the
intrinsic and extrinsic muscles ; it is mixed up with some delicate
cellular and adipose tissue. The intrinsic muscles consist, 1st,
of a superficial lingual muscle ; 2d, of two deep-seated, all of

464 STRUCTURE OF THE TONGUE.

which are longitudinal ; 3d, of transverse muscular fibres,
reunited at the raphe, in the middle line of the tongue ; 4th, of
some vertical fibres which are inserted on the lower surface of
the mucous membrane. The ligament from the os hyoides
extended along the middle line of the tongue, Blandin calls the
lingual cartilage. The evidence in favor of its cartilaginous
nature, is not very satisfactory in man. The epidermis of the
tongue, which is much thicker than that of other portions of the
mouth, forms, according to Blandin, a sheath open at top, round
the sensitive papilla, which protects them when the tongue
acts as an instrument of mastication, and through which the
papillae protrude, to come fully in contact with the sapid sub-
stance when tumefied or erected by the gustatory excitement. —

In addition to these, are the extrinsic muscles, which origi-
nate from the neighboring parts, and are inserted and continued
into the substance of the tongue. See fig. 122.

Among the most important of the muscles, are those which
proceed from the chin, or the genio-hyo-glossi. They are in
contact with each other ; their fibres radiate from a central
point on the inside of the chin, and are inserted into the middle
of the lower surface of the tongue : the insertion commencing
at a short distance from its apex, and continuing to its base.

As the genio-hyo-glossi muscles have a considerable degree
of thickness, they add much to the bulk of the tongue in the
middle of the posterior parts of it.

The hyo-glossi and the stylo-glossi, being continued into the
posterior and lateral parts, contribute also to the bulk of these
parts.

The tongue, thus composed and connected, lies, when at
rest, on the mylo-hyoidei muscles ; and the space between it
and these muscles is divided into two lateral parts by the above
described genio-hyo-glossi. In the space above mentioned, is
a small salivary gland, of an irregular oval form ; the greatest
diameter of which extends from before backwards, and its
«dges present outwards and inwards. It has several excretory
ducts, the orifices of which form a line on each side of the
tongue. This gland is very prominent under the tongue ; and

PAPILLAE OF THE TONGUE. 465

when the tongue is raised it is particularly conspicuous : it is
called the Sublingual.

The lining membrane of the mouth continues from the inside
of the alveoli of the lower jaw, which it covers, over the sublin-
gual glands to the lower surface of the tongue. In this situa-
tion it is remarkably thin ; but, as it proceeds to the upper
surface of the tongue, its texture changes considerably, and on
this surface it constitutes the organ of taste.

The upper surface of the tongue, although it is continued
from the thin membrane above described, is formed by a
rough integument which consists, like the skin, of three lamina.
The cuticle is very thin ; and under it, the rete mucosum* is
thicker and softer than in other places.

The true skin here abounds with eminences of various sizes
and forms, all of which are denominated Papilla. The largest
of these are situated on the posterior part of the tongue, and
are so arranged that they form an angle rather acute, with its
point backwards. They are commonly nine in number : they
resemble an inverted cone, or are larger at their head than their
basis. They are situated in pits or depressions, to the bottoms
of which they are connected. In many of them there are
follicles, or perforations, which have occasioned them to be
regarded as glands. They are called Papilla Maxima, or
Capitata.

The papillae, next in size, are denominated fungiform by
some anatomists, and Media or Semilenticulares by others.
They are nearly cylindrical in form, with their upper extremi-
ties regularly rounded. They are scattered over the upper
surface of the tongue, in almost every part of it, at irregular
distances from each other.

The third class are called conoidal or villous. They are
very numerous, and occupy the greatest part of the surface of
the tongue. Although they are called conoidal, there is a great

* M. Bichat appears to have had doubts whether the real rete mucosum
existed here. He says that he could only perceive a decussation of vessels in
the intervals of the papillae, which, as he supposes, occasioned the florid color
of the tongue.

-466 PAPILLA OF THE TONGUE.

difference in their form ; many of them being irregularly angular
and serrated as well as conical.

Soemmering and other German anatomists consider the
smallest papillae as a fourth class, which they call the filiform:
these lie between the others.

It is probable that these papillae are essential parts of the
organ of taste ; and their structure is of course an interesting
object of inquiry.

The nerves of the tongue have been traced to the papillae,
and have been compared by some anatomists to the stalk of
the apple, while the papillae resembled the fruit ; but their
ultimate termination does not appear to have been ascer-
tained.*

— The papillae maximae or capitatae, are supplied, accor-
ding to Cloquet, by filaments from the glosso-pharyngeal
nerve, the fungiformes by filaments from the fifth. The
papillae maximae appear to consist only of a collection of
mucous follicles, which differ only from those of the soft palate
and lips, by standing out more in relief.

— The follicles of each papilla open occasionally upon the side;
several open by a common orifice at the top of the papilla,
which is often very visible to the naked eye, as a little reddish
point. Weber succeeded in injecting this orifice with mercury,
and found it led to a central cavity irregularly divided by septae
into cells, visible to the naked eye, having some resemblance
to, but much larger than those of the parotid. Other mucous
follicles of a simpler kind are spread over the whole surface of
the tongue between the smaller papillae. Some are mere
small pouches, opening by simple orifices, without canals.
Others are more complicated, and according to Weber, who
filled them with mercury, have ducts three or four lines in
length, which run down between the muscular fibres of the

* In the explanation of the plates, referred to in the following sentence,
Soemmering observes, that when the fibrillaB of the lingual nerve of the fifth
pair are traced to the papillae of the second class, they swell out into a conical
form ; and these nervous cones are in such close contact with each other, that
the point of the finest needle could not be insinuated into the papillae without
touching a nerve.

BLOOD-VESSELS OF THE TONGUE. 467

tongue, to terminate in little flattened sacs divided into several

cells, and having sometimes, a diameter of three lines.

— From all these follicles, comes that profusion of muoous

secretion, which we see covering the tongue in diseases.

— He describes the sebaceous glands of the skin as being

analogous in structure to these follicles, as well as those of the

trachea and of the inside of the lips and cheeks. —

Soemmering has lately published some elegant engraved
copies of drawings of these papillae, when they were magnified
twenty-five times ; from which it appears that a very large
number of vessels, particularly of arteries, exist in them.
These vessels are arranged in a serpentine direction, and are
prominent on the surface ; but they appear doubled, and the
most prominent part is the doubled end. — This arrangement
of vessels is perceptible on the sides of the tongue, as well as
on the papillae. —

Behind the large papillae is a foramen, first described by
Morgagni, and called by him Foramen Cwcum. It is the
orifice of a cavity which is not deep ; the excretory ducts of
several mucous glands open into it.

On the upper surface of the tongue, a groove is often to be
seen, which is called the linea mediana, and divides it into two
equal lateral parts.* Below, the lining membrane of the mouth,
as it is continued from the lower jaw to the tongue, forms a
plait, which acts as a ligament, and is called the frcenum lingua.
It is attached to the middle of the tongue, %at some distance
behind the apex. t

The tongue is well supplied with blood-vessels, which are
derived Irom the lingual branch of the external carotid on
each side. This artery passes from the external carotid,
upwards, inwards, and forwards, to the body of the tongue.
In this course it sends off several small arteries to the contig-
uous parts, and one which is spent about the epiglottis and the
adjoining parts, called the Dorsalis Lingua. About the
anterior edge of the hyo-glossus muscle, it divides into two

* This groove indicates the position of the middle raphe of Gerdy.

468 BLOOD-VESSELS OF THE TONGUE.

large branches: one of which, called the Sublingual^ passes
under the tongue between the genio-hyo-glossus and the sub-
lingual gland, and extends near to the symphysis of the upper
jaw ; sending branches to the sublingual gland, to the muscles
under the tongue, to the skin, and the lower lip. The other is
in the substance of the tongue, on the under side near the sur-
face, and extends to the apex.

The veins of this organ are not so regular as the arteries :
they communicate with the external jugular, and some of them
are always very conspicuous under the tongue : these are called
ranular.

It is to be observed, that the vessels on each side have but
little connexion with each other ; for those of one side may be
injected while the others continue empty.

The tongue is also well supplied with nerves, and derives
them from three different sources on each side, namely, from the
fifth, the eighth, and ninth pairs of the head.

The lingual portion of the third branch of the fifth pair pass-
ing under the tongue, enters its substance about the middle, and
forms many minute branches, which pass to the papillae of the
forepart of the tongue.

The glosso-pharyngeal portion of the eighth pair, sending off
several branches in its course, passes to the tongue near its basis,
and divides into many small branches, which are spent upon the
sides and middle of the root of the tongue, and also upon the
large papillae.

The ninth pair of nerves are principally appropriated to the
tongue. They pass on each side to the most fleshy part of it,
and after sending one branch to the mylo-hyoideus, and another
to communicate with the lingual branch of the fifth pair, they
are spent principally upon the genio-glossi, and linguales
muscles.

The tongue answers a threefold purpose. It is the princi-
pal organ of taste. It is a very important agent in the articu-
lation of words, and it assists in those operations upon our food,
which are performed in the mouth.

PAROTID GLAND. 469

The Salivary Glands.

The salivary glands have such an intimate connexion with
the mouth that they may be described with it.*

There are three principal glands on each side : the Parotid,
Submaxillary, and the SublinguaL They are of a whitish or
pale flesh color, and are composed of many small united masses
or lobuli, each of which sends a small excretory duct to join
similar ducts from the other lobuli, and thereby form the great
duct of the gland.

The Parotid is much larger than the other glands. It
occupies a large portion of the' vacuity between the mastoid
process and the posterior parts of the lower jaw. It extends
from the ear and the mastoid process over a portion of the
masseter muscle, and from the zygoma to the basis of the lower
jaw. Its name is supposed to be derived from two Greek
words which signify contiguity to the ear. It is of a firm con-
sistence. It receives branches from the external carotid artery
and from its facial branch.

From the anterior edge of this gland, rather above the middle,
the great duct proceeds anteriorly across the masseter muscle ;
and, after it has passed over, it bends inward through the adipose
matter of the cheek to the buccinator muscle, which it perforates
obliquely, and opens on the inside of the cheek opposite to the
interval between the second and third molar teeth of the upper
jaw. The aperture of the duct is rather less than the general
diameter of it, and this circumstance has the effect of a valve.
When the duct leaves the parotid, several small glandular
bodies called sociae parotidis, are often attached to it, and their
ducts communicate with it. The main duct is sometimes called
ductus stenoMyinus, after Steno, who first described it.

When the mouth is opened wide, as in gaping, there is often
a jet of saliva from it into the mouth.

The parotid gland furnishes the largest proportion of saliva.

It covers the nerve called Portio Dura, after it has emerged
from the foramen stylo-mastoideum.

* For a further account of glands, see General Anatomy of Glandular
System.

40

470 ULTIMATUM STRUCTURE OF THE SALIVARY GLANDS.

. «.

— This nerve after being covered a short distance by the
gland, enters its substance, and forms there the plexus called
pas anserinus, so as to leave a portion of the gland on the inner
face of the nerve. The external carotid artery likewise traverses
the gland and is situated rather more exteriorly than the nerve,
so as to leave about one-third of the gland on its inner face.
Branches from the artery* are sent off in various directions
as it traverses the gland, to the face, and to the structure of the
gland itself.

— The duct of Steno, is very feebly attached to the surrounding
parts, and is accompanied by many branches of the middle
division of the facial nerves, and some small arteries which
supply its walls ; it is covered only by the skin, some adipose
tissue, by some fibres of the platysma myoides, and the
zygomaticus major which crosses it obliquely. Its general
diameter is about a line ; and it is very distensible. It will be
found, according to the rule laid down by Dr. Physick,
under a line drawn from the lobe of the ear, to the tip of the
nose.

119. — The duct is composed of two coats, one,
external, white, fibrous, and resisting; the
other, internal, is a mucous membrane, con-
tinuous with the lining membrane of the
mouth, and appears to differ from it only in
being paler.

— Fig. 119, is a microscopical representation
of the structure of a portion of the parotid
gland of a young infant, after it had been
minutely injected with mercury from the duct of Steno, by E.
H. Weber, of Leipzic. The small figure, to the right, is the
natural size of the piece magnified, in which the salivary ducts
were filled with the fluid to their very terminations. A branch
of the salivary duct, is seen on the right margin of this figure,
ramifying like the branch of a tree. These ramifications never
anastomose together, and are of much greater size than the
capillary blood-vessels. Each ramification, at its termination,
resolves itself into cells densely compacted together, like a

THE SUBMAXILLARY GLAND. 471

bunch of grapes upon its stem, a, a, a. Some of the cells
open by a minute excretory tube directly into the salivary
duct. In other instances some of the ducts of the cells uffite
into a common tube, before entering the salivary duct. The
cells are not round, and vary among themselves in regard to
size.

— The- average diameter of these cells, measured by a micro-
meter, were found by Weber, to be the ^gth part of an inch,
which he finds to be three times greater than that of the most
delicate sanguineous vessels. The cellular structure of the
parotid, seems therefore to be very analogous to the cellular
structure of the lungs discovered by Soemmering and Reisseis-
sen, the cells of the lungs, however, being five or six times
larger than those of the parotid. The elaborate researches of
Weber and Muller, have shown also that this is the common
mode of termination of the excretory ducts in the different
glands of the body ; viz. that they terminate in closed cells,
upon which ramify the delicate secretory capillary vessels. —

The second gland is called the Submaxillary. It is much
smaller than the parotid, and rather round in form. It is
situated immediately within the angle of the lower jaw,
between it on the outside, and the tendon of the digastric
muscle and the ninth pair of nerves internally. Its posterior
extremity is connected by cellular membrane to the parotid
gland ; its anterior portion lies over a part of the mylo-hyoideus
muscle ; and from it proceeds the excretory duct, which is of
considerable length, and passes between the mylo-hyoideus
and genio-glossus muscles along the under and inner edge of
the sublingual gland. In this course the duct is sometimes
surrounded with small glandular bodies, which seem to be
appendices to the sublingual gland. It terminates under the
tongue, on the side of the fraenum linguae, by a small orifice
which sometimes forms a papilla.* (See fig. 118, p. 454.)

* Lassus informs us that Oribases, afterwards all the Arabians, and subse-
quently Guy De Chauliac, Lanfranc, Achillini, Berenger De Carpi, Charles
Etienne, Casserius and several others have given the description of these salivary
ducts ; notwithstanding which, Wharton, a physician of London, attributed to
himself the discovery of them on the bullock, in 1656. — u.

472 SUBLINGUAL GLAND.

The orifice is often smaller than the duct ; in consequence of
which, obstruction frequently occurs here, and produces the
disease called ranula.

The Sublingual gland, which has already been mentioned,
lies so that, when the tongue is turned up, it can be seen pro-
truding into the cavity of the mouth, and covered by the lining
membrane, which seems to keep it fixed in its place. It lies
upon the mylo-hyoideus, by the side of the genio-hyoideus ;
and is rather oval in form, and flat. Its greatest length is from
before backwards ; its position is rather oblique, one edge being
placed obliquely inwards and upwards, and the other outwards
and downwards. It has many short excretory ducts, which
open by orifices arranged in a line on each side : they are
discovered with difficulty on account of their small size, and
sometimes amount to eighteen or twenty in number. In some
few instances, this gland sends off a single duct, which com-
municates with the duct of the submaxillary gland.

— The duct of the Submaxillary gland is called the duct of
Wharton, (ductus Whartonionus) from an English anato-
mist who first described it. It is accompanied in nearly the
whole of its course by the lingual branch of the fifth pair of
nerves.

— The usual arrangement of the ducts of the sublingual
gland is as follows : six or eight run from the upper part of the
gland, to open by the side of the fraenum linguae. Five or six
others proceed from its sides to open separately in the mucous
membrane above the gland. Several open into the duct of
Wharton which runs by the side of the gland ; these most
frequently unite to form a single duct, called the duct of Bar-
tholinus, or duct of Rivinus. This I have frequently succeeded
in distending with mercury from the duct of Wharton.
— The structure and office of these salivary glands appear the
same, and not unfrequently a slight continuation of structure is
observed at the two extremities of the submaxillary gland. —

The salivary fluid secreted by these glands is inodorous,
insipid, and limpid, like water ; but much more viscid, and of
greater specific gravity. Water constitutes at least four-fifths

OBSERVATIONS ON THE TONGUE. 473

of its bulk ; and animal mucus one half of its solid contents.
It also contains some albumen ; and several saline substances ;
as the muriate of soda, and the phosphates of lime, of soda, and
of ammonia.

It is probable that this fluid possesses a solvent power with
respect to the articles of food.

There are small glandular bodies, situated between the
masseter and buccinator muscles, opposite to the last molar
tooth of the upper jaw, whose nature is not well understood :
they are called Glandula molares. They are believed to be
mere mucous glands.

The motions of the tongue are very intelligible to a person who has a prepara-
tion of the lower jaw before him, with the tongue in its natural situation, and
the muscles which influence it, properly dissected. Its complicated move-
ments will appear the necessary result of the action of those muscles upon it,
and the os hyoides ; and also upon the larynx, with which the os hyoides is
connected. The muscular fibres of the tongue itself are also to be taken
into this view, as they act a very important part.

Although the tongue appears very necessary, in a mechanical point of view, to
the articulation of many words, yet there are cases where it has been entirely
deficient, in which the parties thus affected, have been able to speak very well
in general, as well as to distinguish different tastes.*

The tongue is also a very delicate organ of touch. — We can perceive the form
of the teeth, and the state of the surface of the mouth, more accurately by
the application of the tongue than of the fingers.

On the three nerves which go to the tongue, it is generally supposed that the
lingual portion of the third branch of the fifth pair is most immediatety con-
cerned in the function of tasting, as it passes to the front part of the surface
of the tongue. The glosso-pharyngeal are probably concerned in the same
function on the posterior part, while the ninth pair of nerves seems principally
spent upon the muscular parts of the organ.

It is obvious that the tongue is most copiously supplied with nerves. This
probably accounts for the great facility of its motions, and the power of con-
tinuing them.

* There is a very interesting paper on this subject, in the Memoirs of the Academy of
Sciences for the year 1718, by Jussieu ; in which he describes the case of a female fifteen
years old, examined by himself, who was born without a tongue. In this paper he refers to
another case, described by Rolland, a surgeon of Saumur, of a boy nine years old, whose
tongue was destroyed by gangrene. In each of these cases the subject was able to articulate
very well, with the exception of a few letters ; and also enjoyed the sense of taste.

40*

474 OF THE THROAT.

CHAPTER XIV.

OF THE THROAT.

To avoid circumlocution, the word throat is used as a
general term to comprehend^ the structure which occurs behind
the nose and mouth, and above the ossophagus and trachea.
This structure consists,

1st. Of the parts immediately behind the mouth, which con-
stitutes the Isthmus of the Fauces :

2d. Of the parts which form the orifice of the windpipe, or
the Larynx ; — and

3d. Of the muscular bag, which forms the cavity behind the
nose and mouth, that terminates in the oesophagus or the
Pharynx.

Of the Isthmus oj the Fauces.

In the back part of the mouth, on each side, are to be seen
the two ridges or half arches, passing from the soft palate to
the root of the tongue, (see fig. 118, p. 454,) formed by plaits
of the mucous membrane, containing muscular fibres. The
anterior plait, which contains the muscle called Constrictor
Isthmi Faucium, passes directly from the side of the root of
the tongue to the palate, and terminates near the commence-
ment of the uvula. The posterior plait runs from the palate
obliquely downwards and backwards, as it contains the palato-
pharyngeus muscle, which passes from the palate to the upper
and posterior part of the thyroid cartilage.

In the triangular space between these ridges is situated a
glandular body, called the Tonsil or Amygdala.* This gland

* It is named amygdala, from its resemblance in form and appearance to an
almond covered by its shell. The exterior or adhering surface of the tonsil
gland is connected by the means of cellular tissue to the superior constrictor
muscle of the pharynx.

The internal carotid artery is situated behind and to the outer side of the
tonsil, and separated from it only by the constrictor muscle, and cellular tissue.

It has been wounded in opening abscesses of the tonsils, when the cutting
instrument has been inclined too much outwards and backwards. — r.

TONSILS. EPIGLOTTIS. 475

has an oval form, its longest diameter extending from above
downwards. * Its surface is rather convex, its natural color is
a pale red. On its surface are the large orifices of many cells
of considerable size, which exist throughout the gland. These
cells often communicate with each other, so that a probe can
be passed in at one orifice and out at the other.

Into these cells open many mucous ducts, which discharge
in part the mucus of the throat, for the purpose of lubricating
the surface, and facilitating the transmission of food.

— In its healthy state, the free surface of the tonsil glands,
are a little below the level of the two half arches of each side.
— But when their cells are distended by inflammation, or effaced
by granulations, as in tonsillitis, they sometimes project beyond
the half arches so as nearly or quite to meet in the middle
line. —

The epiglottis, or fifth cartilage of the larynx, is situated at
the root of the tongue, in the middle, between the tonsils. The
part which is in sight is partly oval in form, and of a whitish
color. Its position, as respects the tongue, is nearly perpen-
dicular, and its anterior surface rather convex.

The mucous membrane continued from the tongue over the
epiglottis is so arranged that it forms a plait, which extends
from the middle of the root of the tongue along the middle of
the anterior surface of the epiglottis, from its base upwards.

On each side of this plate or fraenum, at the junction of the
surfaces of the tongue and of the epiglottis there is often a de-
pression, in which small portions of food sometimes remain ;
and a small fraenum, similar to that above described, is sometimes
seen on the outside of each of these cavities.

The epiglottis is situated immediately before the opening
into the larynx.

The above described parts can be well ascertained in the
living subject, by a person who has a general knowledge of the
structure. Thus, looking into the mouth, with the tongue de-
pressed, the uvula and soft palate are in full view above, and
the epiglottis is very perceptible below ; while the two ridges

476 THE LARYNX.

or lateral half arches can be seen on each side, with the tonsil
between them.

Of the Larynx. f

— The larynx is situated immediately below the os hyoides,
and is continuous at its inferior part with the trachea, to which
it is attached, like a capital upon a column. It serves a double
purpose ; that of a tube for the introduction of air into the
lungs ; and that of a very complicated apparatus for the pro-
duction of the voice.

— It is composed of cartilages which form its frame-work, liga-
ments and synovial capsules which unite the cartilages together,
muscles to put them into motion, and an exquisitely sensitive
mucous membrane, that lines the whole of its interior. It is
larger and much more prominent in males than females, and
undergoes a rapid and remarkable degree of development,
both in regard to size and energy of function at the period of
puberty. —

In this structure are five cartilages, upon which its form and
strength depends, namely, the Cricoid, the Thyroid, the two
Arytenoid, and the Epiglottis. These cartilages are articulated
to each other, and are supplied with muscles by which certain
limited motions are effected.

The basis of the structure is a cartilaginous ring, called the
cricoid cartilage, and which may be considered as the com-
mencement of the windpipe.

It may be described as an irregular section of a tube : its
lower edge connected with the windpipe, being nearly hori-
zontal when the body is erect ; and the upper edge very oblique,
sloping from before, backwards and upwards ; in consequence
of this, it has but little depth, before, but is eight or nine lines
deep behind.

— In front, and upon each side of the middle line there is a
depression, in which arises the two crico-thyroid muscles. Upon
each side, and near its upper and outer surface, there is a
smooth convex facet, upon which is articulated, the corres-

CRICOID CARTILAGE. THYROID CARTILAGE. 477

ponding facet of the inferior cornua of the thyroid cartilage.
Posteriorly are two slight vertical depressions, to which are
attached the crico-arytenoidei postici muscles. Its internal fcrce
is covered by mucous membrane. Its superior border gives
attachment in front to the crico-thyroid membrane, on the sides
to the lateral crico-arytenoid muscles, and posteriorly presents
a little notch, limited by two convex facets upon which are
articulated the arytenoid cartilages. —

The Thyroid cartilage is a single plate, bent in such manner
that it forms an acute angle with two similar broad surfaces
on each side of it. It is so applied to the cricoid cartilage, that
the lower edge of the angular part is at a small distance above
the front part of that cartilage, and connected to it by ligamen-
tous membrane ; while its broad sides are applied to it later-
ally, and thus partially enclose it.

The upper edge of the angular part of the thyroid cartilage
forms a notch ; and the natural position of the cartilage is such,
that this part is very prominent in the neck ; it is called the
Pomum Adami.

Both the upper and lower edges of the thyroid cartilage
terminate posteriorly in processes, which are called Cornua.
The two uppermost are longest : they are joined by ligaments
to the extremities of the os hyoides. The lower and shorter
processes are fixed to the cricoid cartilage. The thyroid car-
tilage, therefore, partly rests upon the cricoid cartilage below,
and is attached to the os hyoides above. It is influenced by the
muscles which act upon the os hyoides, and also by some mus-
cles which are inserted into itself. It is moved obliquely
downwards and forwards in a slight degree upon the cricoid
cartilage, by a small muscle, the crico-thyroideus, which
arises from that cartilage and is inserted into it.

— The external lateral surface of the thyroid cartilage is
slightly concave, and across it, passes a small ridge obliquely
from above downwards, and from behind forwards, which
gives attachment above to the thyro-hyoid and below to the
sterno-hyoid muscles. The posterior or inside face of the
Pomum Adami presents an entering angle, where the two

478 ARYTENOID CARTILAGES.

symmetrical sides of the cartilage meet, and in which is
attached the thyro-arytenoid muscles, the pedicle of the epi-
glottis and one end of the vocal ligaments. The upper margin
of the cartilage presents a curved appearance like that of the
italic long /; a similar curvature is also observable on its pos-

terior margin. —

Fig. 120.* The ^Arytenoid cartilages are two small

bodies of a triangular or pyramidal form
anc^ slightty curved backward. They are
placed upon the upper and posterior edge
of the cricoid cartilage, near to each other ;
their upper ends, taken together, resem-
ble the mouth of a pitcher or ewer ; from
_ which circumstance their name is derived.

Their bases are broad ; and on their lower surfaces is a cavity,
which corresponds with the convex edge of the cricoid carti-
lage, to which they are applied. At these places, a regular
movable articulation is formed, by a capsular ligament between
each of these cartilages and the cricoid, in consequence of
which they can be inclined backward or forward, inward or
outward.

From the anterior part of each of these cartilages, near the
base, a tendinous cord passes forward, in a direction which is
horizontal when the body is erect, to the internal surface of the
angle of the thyroid. These ligaments are not perfectly parallel
to each other ; they are nearer before than behind. The
aperture between them is from two to five lines wide when the
muscles are not in action ; and this aperturef is the orifice of
the windpipe : for the exterior space, between these ligaments
and the circumference of the thyroid, is closed up by mem-

* Vertical section of the larynx, h, Os hyoides. t, Thyroid cartilages, c c,
Cricoid cartilage, a, Arytenoid cartilage, v, Ventricle of the larynx, bounded
below by the ligamenta vocales, and above by the superior ligaments of the
glottis, e, Epiglottis cartilage, g, Ligamentous attachment of the tongue to
the os hyoides. b, Trachea cut off at the third ring. The lining membrane is
left out in this section.

f It forms also the rima glottidis of the larynx.

EPIGLOTTIS. 479

brane and muscle. At a small distance above these ligaments
are two others, which also pass from the arytenoid to the thyroid
cartilages. They are not so tendinous aud distinct as -the
first mentioned, and cannot be drawn so tense by the
muscles of the arytenoid cartilages. They are also situated
at a greater distance from each other, and thus form a large
aperture.

On the external side of the upper extremity of each of the
arytenoid cartilages, and nearly in contact with it, is a small
cartilaginous body, not so large as a grain of wheat, and
nearly oval in form. These are connected firmly to the aryte-
noid cartilages, and are called their Appendices.* Being in the
margin of the aperture of the larynx, they have an effect upon
its form.

The arytenoid cartilages are the posterior parts of the larynx.
The Epiglottis, which has already been mentioned is the
anterior. When this cartilage is divested of its membrane,
it is oval in its upper extremity, and rather angular below,
terminating in a long narrow process, which is like the stalk of
a leaf.

It is firmly attached to the internal surface of the angular
part of the thyroid by this lower process ; and, being placed in
a perpendicular position, one of its broad surfaces is anterior —
towards the tongue, and the other posterior — towards the opening
of the windpipe.

It is attached to the os hyoides by dense cellular texture or
ligament, and to the tongue by those plaits of the membrane of
the mouth which have been already described.

It is elastic, but more flexible than the other cartilages ; being
somewhat different in its structure. Its surface is perforated by
the orifices of many mucous ducts.

There is a small space between the lower part of this carti-
lage, and the upper part of the thyroid and the ligamentous
membrane passing from it to the os hyoides. In this is a sub-
stance, which appears to consist of glandular and of adipose

* They are also called Cornicula Laryngis, Tubercles of Santorini. — p.

480 VENTRICLE OF GALEN OR MORGAGNI.

matter, (see fig. 120.) It is supposed that some of the orifices
on the lower part of the epiglottis communicate with this
substance.

— This substance is a collection of mucous glands, called
glandules epiglottidtz ; the ducts which arise from them are
twenty or thirty in number, and perforate the, epiglottis to throw
their mucus on the side of^the larynx. —

In the erect position of the body, the epiglottis is situated
rather higher up than the arytenoid cartilages, and at the dis-
tance of ten or twelve lines from them.

The mucous membrane which covers the epiglottis, is
reflected backwards from the base of the tongue, and is
extended from each side of it to the arytenoid cartilages, and
being continued into the cavity of the larynx, as well as upon
the general surface of the throat, it is necessarily doubled :
this doubling forms the lateral margins of the orifice of the
cavity of the larynx. In these folds of the membrane are seen
some very delicate muscular fibres, forming the Aryteno-epi-
glottideus muscle.

— The epiglottis maintains its vertical position, partly from
its own elasticity of structure, and partly from the folds of
mucous membrane, reflected to it from the tongue, which contain
some yellow elastic ligarnentous fibres. —

The membrane continues down the cavity of the larynx,
and, covering the upper ligaments, penetrates into the vacuity
between them and the lower ligaments, so as to form a cavity
on each side of the larynx, opening between the two ligaments,
which is called the Ventricle of MorgagnL The shape of
each cavity is oblong. Its greatest length extends from
behind forward, on each side of the opening into the windpipe
formed by the two lower or principal ligaments ; so that when
the larynx is removed from the subject, upon looking into it
from above, you perceive three apertures : one in the middle,
formed by the two lower ligaments ; and one on each side of
it, between the lower and upper ligament, which is the orifice
of the ventricle of Morgagn^.
— If a probe be passed* into this ventricle of the larynx, or ven-

VENTRICLE OF GALEN OR MORGAGNI RIMA GLOTTIDIS. 481

tricle of Morgagni, it will be found to pass much above the supe-
rior thyro-arytenoid ligament, into a prolongation of the cavity of
Fig. 121.* the ventricle, which extends as high as^the
upper margin of the thyroid cartilage, and
which has been called by Mr. Hilton, the
Sacculus Laryngis. It was pointed out
by Morgagni, and has been compared by
M. Cruvielhier, from its shape, to a Phry-
gian casque. — It is apt to escape observation
in the healthy state. When death has taken
place, from pulmonary emphysema, or lar-
yngeal phthisis, I have, on several occasions, found the sac so
large as to project considerably above the thyroid cartilage.
The ventricle and its sac, appear to be intended for the supply of
a lubricating secretion to the vocal chords, which are kept in
such constant action, during respiration and phonation. The sur-
face of the cavity, is studded with sixty or seventy small follicu-
lar glands, which are seated in the submucous tissjue, and give
to the mucous membrane, when dissected out, a rough appear-
ance. The greater part of these follicles is placed in the sac,
and the fluid which they form, is directed upon the rima glottidis,
by two small folds of mucous membrane, at the entrance of
the sacculus. —

The aperture between the two lower ligaments is called the
Rima Glottidis, or Chink of the Glottis; the upper aperture,
formed by4 the fold of the membrane and extending from the
epiglottis to the arytenoid cartilages, may be termed Glottis.

— The folds of the membrane forming the upper margin of
the glottis is loose and distensible, and is liable in laryngeal
inflammation to become oedematous and bag out so as to im-
pede respiration to a great extent, and even produce suffoca-
tion.—

If the windpipe is divided near the larynx, and the larynx
inverted, so that the rima glottidis may be examined from
below, the structure appears still more simple: it resembles a

* Front view of the larynx ; plan of its interior cavity, represented by the
lines a c, b b. /s, Superior ligaments of the glottis. U, Inferior ligaments.

41

482 GLOTTIS.

septum fixed abruptly in the windpipe, with an aperture in it
of the figure of the rima glottidis.

The anterior surface of the two arytenoid cartilages is con-
cave. This concavity is occupied in each by a glandular
substance, which lies between the cartilage and the lining
membrane ; and extends itself horizontally, covered by the
upper ligament of the glottis. The nature of these bodies is
not perfectly understood ; but they are supposed to secrete
mucus.*

The membrane which lines the cavity of the glottis being
continued from the mouth and throat, resembles the membranes
which invest those parts. In some places, where it is in close
contact with the cartilages, it appears united with the perichon-
drium, and acquires more firmness and density.

The general motions of the larynx are very intelligible to
those who are acquainted with the muscles which are con-
nected with the thyroid cartilage, and which move the os hy-
oides. They take place particularly in deglutition, and in
some modifications of the voice ; and also in vomiting.f

The motions of the particular cartilages on each other can
also be well understood, by attending to the origin and inser-
tion of the various small muscles connected with them. The
most important of these muscles are the crico-arytenoidei pos-
tici and laterales, the thyreo-arytenoidei, the arytenoidei obli-
qui, and the arytenoideus transversus. The effects of their
actions appear to be the dilating or contracting the rima glotti-
dis, and relaxing or extending the ligaments which form it.

The arteries of the larynx are derived from two sources,
namely, the superior thyroid, or laryngeal branch of the
external carotid, and the thyroid branch of the subclavian.

The nerves of the larynx also come to it in two very differ-
ent directions on each side. It receives two branches from the
par vagum ; one which leaves that nerve high up in the neck,
and is called the Superior Laryngeal branch ; and another

* They constitute the glandulce arytenoidea. — p.

•j- For an excellent exposition of the uses of the larynx, see Dunglison's
Physiology, 5th edition. —

VESSELS AND NERVES OF THE LARYNX. 483

which proceeds from it after it has passed into the cavity of the
thorax, and is called from its direction the Recurrent.

— According to M. Blandin, who has rather recently m#de
some research upon this subject, the superior laryngeal nerve,
is distributed chiefly to the mucous membrane and cryptae of
the larynx ; it likewise sends some filaments to the arytenoid
and crico-thyroid muscles, and others which anastomose with
the branches of the recurrent. The recurrent supplies all the
muscles of the larynx, with the exception of the crico-thyroid.
There is still among anatomists some difference of opinion in
regard to the distribution of these nerves. —

Muscles of the Larynx.

These are divided into extrinsic and intrinsic.
— The extrinsic muscles, which are attached by but one extre-
mity to the larynx, have been already described. They consist
of the sterno-hyoid, omo-hyoid, sterno-thyroid, and thyreo-
hyoid ; to which might indeed be added, all the muscles of the
supra-hyoid region, and those of the pharynx, which are
attached to the cricoid and thyroid cartilages. These, when
they act upon the organ, move the entire larynx.
— The intrinsic muscles, are attached by both extremities to
different parts of the larynx, and produce various movements
in the different pieces of which it is composed. There are ten,
viz., five pairs, and one single muscle which are called the
muscles of the chorda vocales, and rima glottidis. Those
which exist in pairs are the crico-thyroid, the crico-arytenoidei
postici, the crico-arytenoidei lateralis, the thyro-arytenoidei
and the arytenoidei obliqui. The single muscle is the aryte-
noideus transversus. The oblique and the transverse arytenoid
muscles consist, but of a few thin fibres with difficulty distin-
guished from each other and are spoken of by many anato-
mists, as a common muscle, called simply the arytenoid.
— There are three other minute muscles, which are called the
muscles of the epiglottis, viz. the thyro-epiglottideus, the
aryteno-epiglottideus superior, and another muscle lately
observed by Mr. Hilton, called aryteno-epiglottideus inferior.

484

MUSCLES OF THE LARYNX.

1 . Crico- Thyroideus,

Arises from the side and
forepart of the cricoid car-
tilage, running obliquely up-
wards.

Inserted by two portions:
the first, into the lower part of
the thyroid cartilage ; the se-
cond, into its inferior cornu.

Use. To pull forwards and
depress the thyroid, or to ele-
vate and draw backwards the
cricoid cartilage.

2. Crico- Arytanoideus Pos-

Arises, fleshy, from the back
part of the cricoid cartilage ; and is

Inserted into the posterior part of the base of the arytenoid
cartilage.

Use. To open the rima glottidis a little, and, by pulling back
the arytenoid cartilage, to stretch the ligament so as to make it
tense.

3. Crico- Arytanoideus Later alis,

Arises, fleshy, from the cricoid cartilage, laterally, where it
is covered by part of the thyroid, and is

* The styloid muscles and the muscles of the tongue. 1. A portion of the
temporal bone of the left side of the skull, including the styloid and mastoid
processes, and the meatus auditorius externus. 2, 2. The right side of the lower
jaw, divided at its symphysis ; the left side having been removed. 3. The
tongue. 4. The genio-hyoideus muscle. 5. The genio-hyo-glossus. 6. The
hyo-glossus muscle ; well seen at the base of the tongue. 7. Its portion con-
nected with the os hyoides. 8. The anterior fibres of the lingualis issuing from
between the hyo-glossus and genio-hyo-glossus. 9. The stylo-glossus muscle,
with a small portion of the stylo-maxillary ligament. 10. The stylo-hyoid.
11. The stylo-pharyngeus muscle. 12. The os hyoides. 13. The thyro-hyoi-
dean membrane. 14. The thyroid cartilage. 15. The thyro-hyoideus muscle
arising from the oblique line on the thyroid cartilage. 16. The cricoid cartilage.
17. The crico-thyroidean membrane, through which the operation of laryngo-
tomy is performed. 18. The trachea. 19. The commencement of the oesopha-
gus.

MUSCLES OF THE LARYNX.

485

Inserted into the side of the base of the arytenoid cartilage
near the former.

Use. To open the rima glottidis, by pulling the ligaments
from each other.

Fig. 123.*

4. Thyreo-Arytanoideus,

Arises from the under and back part of
the middle of the thyroid cartilage ; and,
running backwards and a little upwards,
alo.ig the side of the glottis, is

Inserted into the arytenoid cartilage,
higher up and farther forwards than the
crico-arytaenoideus lateralis.

Use. To pull the arytenoid cartilage
forwards nearer the middle of the thyroid,
and consequently to shorten and relax the
ligament of the larynx or glottis vera.

5. Arytanoideus Obliquus,

Arises from the base of one arytenoid cartilage ; and crossing
its fellow, is

Inserted near the tip of the other arytenoid cartilage.

Use. When both act they pull the arytenoid cartilages towards
each other.

N. B. One of these is very often wanting.

The single muscle is, the

Arytanoideus Transversus,

Arises from the side of one arytenoid cartilage, from near its
articulation with the cricoid to near its tip. The fibres run
straight across, and are

Inserted, in the same manner, into the other arytenoid car-
tilage.

* A posterior view of the larynx. 1. The thyroid cartilage. 2. One of its
ascending cornua. 3. One of the descending cornua. 4. 7. The cricoid carti-
lage. 5, 5. The arytenoid cartilages. 6. The arytenoideus muscle, consisting
of oblique and transverse fasciculi. 7. The crico-arytenoidei postici muscles.
8. The epiglottis.

41*

486 MUSCLES OF THE LARYNX.

Use. To shut the rima glottidis, by bringing these two carti-
lages, with the ligaments, nearer one another.

Fig. 124.* Besides these, there are a few separate
muscular fibres on each side ; which, from
their general direction, are named

1. Thyro-Epiglottideus,
Arises, *by a few pale separated fibres,

from the thyroid cartilage : and is
Inserted into the epiglottis laterally.
Use. To draw the epiglottis obliquely

downwards, or, when both act, directly

downwards ; and at the same time, it expands

that soft cartilage.

2. Aryt&no-Epiglottideus, superior.

Arises, by a number of small fibres, from the lateral and
upper part of the arytenoid cartilage ; and, running along the
outer side of the external rima, is

Inserted into the epiglottis along with the former.

Use. To pull that side of the epiglottis towards the external
rima ; or, when both act, to pull it close upon the glottis. It is
counteracted by the elasticity of the epiglottis.

3. Aryteno-Epiglottideus, inferior.

— This muscle may be exposed by raising the mucous mem-
brane immediately above the ventricle of the larynx. It arises
by a narrow and fibrous origin from the arytenoid cartilage,
just above the attachment of the chorda vocalis — and passing
forwards and a little upwards, expands over the upper half or
two-thirds of the sacculus laryngis, and is inserted by a broad
attachment into the side of the epiglottis. Its action according

* A side view of the larynx, one ala of the thyroid cartilage has been
removed. 1. The remaining ala of the thyroid cartilage. 2. One of the
arytenoid cartilages. 3. One of the cornicula laryngis. 4. The crycoid carti-
lage. 5. The crico-arytenoideus posticus muscle. 6. The crico-arytenoideus
lateralis. 7. The thyro-arytenoideus. 8. The crico-thyroidean membrane.
9. One half of the epiglottis. 10. The upper part of the trachea.

THE THYROID GLAND. 487

to Mr. Hilton, is to approximate the epiglottis and arytenoid
cartilage, to compress the subjacent glands which open into the
pouch of the larynx, to diminish the capacity of that cavity
and to change its form. —

The extreme irritability of the glottis is unequivocally demonstrated by the
cough, which is excited when a drop of water, or any other mild liquid, or a
crumb of bread enters it. Notwithstanding this, a flexible tube, or catheter,
has several times been passed into the windpipe through the rima glottidis,
and been endured by the patient a considerable time.

The cough, which occurs when these parts are irritated, does not appear to arise
exclusively from the irritation of the membrane within the glottis; for, if it
were so, mucilaginous substances, when swallowed slowly, could not suspend
it. Their effect in relieving cough is universally known ; and as they are
only applied to the surface exterior to the glottis, it is evident that the irrita-
tion of this surface must also produce coughing.

Several curious experiments have been made to determine the effect of dividing
the different nerves which go to the larynx ; by which it appears that the
recurrent branches supply parts which are essentially necessary to the forma-
tion of the voice ; whilst the laryngeal branches supply parts which merely
influence its modulation, or tone. See Mr. Haigton's Essay on this subject:
Memoirs of the Medical Society of London, vol. iii.

The Thyroid Gland, (see fig. 118, p. 454,)

May be described here, although a part of it is situated
below the larynx.

This body consists of two lobes, which are united at their
lower extremities by a portion which extends across the
anterior part of the windpipe. Each lobe generally rises
upwards and backwards from the second cartilaginous ring of
the windpipe over the cricoid cartilage and a portion of the
thyroid. It lies behind the sterno-hyoidei, and sterno-thyroidei
muscles. It is of a reddish-brown color, and appears to
consist of a granular substance ; but its ultimate structure is
not understood. It is plentifully supplied with blood, and
receives two arteries on each side : one from the laryngeal
branch* of the external carotid : and the other from the thyroid
branch of the subclavian.

Notwithstanding this large supply of blood, there is no

* The main branch from the external carotid, is now more commonly called
superior thyroid. — r.

488 THE THYROID GLAND.

proof that it performs any secretion : for although several
respectable anatomists haVe supposed that they discovered
excretory ducts passing to the windpipe, larynx, or tongue, it
is now generally agreed that such excretory ducts are not to be
found. Several instances, have, however, occurred, in which
air has been forced, by violent straining, from the windpipe into
the substance of this gland.

[There are two membranous expansions in the neck which
should be noticed in its dissection. The first, called Fascia
Superficialis, lies immediately beneath the skin, may be
considered as a continuation of the fascia superficialis abdomi-
nis, and is strongly connected to the base of the lower jaw,
being also spread over the parotid gland. It is not very
distinct in all subjects. The second is called the Fascia Pro-
funda Cervicis ; it extends from the larynx and thyroid gland
to the upper part of the sternum and first ribs ; the great ves-
sels, &,c. of the superior mediastinum are placed immediately
below it.]

— The thyroid gland, gets a thin capsular investment, from two
layers of the deep-seated cervical fascicf, (fascia profunda cer-
mcis) as seen in fig. 125.

— The same fascia likewise gives off layers, that form cellular
investments or tunics to the trachea, oesophagus, and to the
blood-vessels of the neck. Other processes pass off from it
which supply sheaths to the sterno-cleido mastoid and other
muscles of the neck. Between the sheaths of the different
muscles of the neck, dense processes of cellular tissue are con-
tinued, so as to give them all the appearance of being formed
as it were, from a common fascia. At the posterior part of the
neck they are thus indirectly connected with the ligamentum
nuchce. Though this for practical purposes is not considered
the best way for studying the fascia of the neck, it serves to give
an idea of the continuity of the cellular investments, which is so
common throughout the body. The accompanying cut and
explanation is taken from Wilson.

— The two lobes of the thyroid gland, when extended and
measured from side to side are together about three inches in

THE THYROID GLAND. 489

diameter. The lobes extend upwards on the sides of the larynx
and downwards on the oesophagus, and lie upon the inner face
of, and partly covering the primitive carotid artery and internal
jugular vein. That part of the gland which unites the lobes

Fig.

together, and is stretched across the trachea, covering the two
or three usually and sometimes the seven upper rings of the
trachea, is called the isthmus of the gland. From the upper
surface of the isthmus a process of the gland is usually seen

* A transverse section of the neck, showing the deep cervical fascia and its
numerous prolongations, forming sheaths for the different muscles of the neck,
the thyroid gland — trachea, O3sophagus and blood-vessels. As the figure is
symmetrical, the figures of reference are placed only on one side. I. The
platysma myoides. 2. The trapezius. 3. The ligamentum nuchae, from which
the fascia may be traced forwards beneath the trapezius, enclosing the other
muscles of the neck. 4. The point at which the fascia divides, to form a sheath
for the sterno-mastoid muscle (5). 6. The point of reunion of the two layers
of the sterno-mastoid sheath. 7. The^point^of union of the deep cervical fascia
of opposite sides of the neck. 8. Section of the sterno-hyoid. 9. Omo-hyoid
10. Sterno-thyroid. 11. The lateral lobe of the thyroid gland. 12. The
trachea. 13. The oasophagus. 14. The sheath containing the common carotid
artery, internal jugular vein, and pneumogastric nerve. 15. The longus colli.
The nerve in front of the sheath of this muscle is the sympathetic. 16. The
rectus anticus major. 17. Scalenus anticus. 18. Scalenus posticus. 19. The
splenius capitis. 20. Splenius colli. 21. Levator anguli scapulae. 22. Corn-
plexus. 23. Trachelo-mastoid. 24. Transversalis colli. 25. Cervicalis ascen-
dens. 26. The semi-spinalis colli. 27. The multifidus spinoe. 28. A vertical
vertebra. The transverse processes are seen to be traversed by the vertebral
artery and vein.

490 THE PHARYNX.

extending upwards, on the left side over the front surface of
the larynx, to be attached by ligamentous fibres to the os
hyoides. A small muscle called the levator glandule thyroideae,
has been described by Duverney, Soemmering and others, run-
ning down from the os hyoides in front of the larynx to the
upper part of the isthmus of the gland. According to Professor
Homer, its existence is verv. rare, with which opinion my own
more limited observation coincides.

— The lobes of the gland are composed of smaller lobules, and
the spongy structure of the latter, is filled with a yellowish and
somewhat oily fluid. Of the uses of this gland nothing positively
is known. Its importance in the system of the adult cannot
be great, as its removal by extirpation, which has been many
times practised, has not appeared to leave any functional lesion
in the economy. —

Of the Pharynx.

The pharynx is a large muscular bag, which forms the great
cavity behind the nose and mouth that terminates in the
oesophagus.

It has been compared to a funnel, of which the oesophagus
is the pipe ; but it differs from a funnel in this respect, that it is
incomplete in front, at the part occupied by the nose and mouth
and larynx.

It is connected above, to the cuneiform process of the
occipital bone, to the pterygoid processes of the sphenoidal,
and to both the upper and lower maxillary bones. It is in
contact with the cervical vertebrae behind ; and, opposite to the
cricoid cartilage, it terminates in the oesophagus.

If the pharynx and oesophagus be carefully dissected and
detached from the vertebrae, preserving the connexion of the
pharynx with the head, and the head then be separated from
the body, by dividing the articulation of the atlas and the os
occipitis, and cutting through the soft parts below the larynx,
the resemblance to a funnel will be very obvious.

In this situation, if an incision be made from above down-
wards through the whole extent of the posterior part of the

STRUCTURE OF THE PHARYNX. 491

pharynx, the communication of the nose, mouth, and windpipe,

with this cavity, will be seen from behind at one view.

The openings into the nose, or the posterior nares, appear

uppermost. Their figure is irregularly oval, or oblong ; they

are separated from each other by a thin partition, the vomer.

Immediately behind, on the external side of each of these orifices,

is the Eustachian tube. (See fig. 118, p. 454.)

The soft palate will appear extending from the lower

boundary of the posterior nares, obliquely backwards and

downwards, so as nearly to close the passage into the mouth.

The uvula hangs from it ; and, on each side of the uvula, the

edge of the palate is regularly concave.

Below the palate, in the isthmus of the fauces, are the

ridges or half arches, and the tonsils between them. The half

arch which presents first, in this view, runs obliquely downward

and backward, and not parallel to the other.

Close to the root of the tongue is the epiglottis erect ; and

immediately adjoining it, is an aperture large enough to admit

the end of a middle-sized finger. This aperture is widest at
the extremity next to the epiglottis, and rather narrower at the
other extremity : it is the glottis or opening of the windpipe.

When the larynx is elevated, the epiglottis can be readily
depressed so as to cover it completely.

The extremities of the arytenoid cartilages, and their
appendices, may be recognized at the posterior edge of the
glottis. At a short distance below this edge, the oesophagus
begins.

The Pharynx is composed of the membrane continued from
the nose and mouth internally, and of a stratum of muscular
fibres externally. The internal membrane is very soft and
flexible and perforated by many muciferous ducts. The
surface which it forms is rather rough, owing to the mucous
glands which it covers. It has a red color, but not so deep
as that of some other parts. It is connected to the muscular
stratum by a loose cellular membrane.

The muscular coat consists of three different portions, which
are considered as so many distinct muscles. They are called

492 CONSTRICTOR MUSCLES OF THE PHARYNX.

the superior, middle, and inferior constrictor muscles of the
pharynx.

The fibres of each of these muscles originate on 'each side,
and run in an oblique direction to meet in the middle, thus
forming the posterior external surface of the dissected pharynx.

The fibres of the upper muscles originate from the cuneiform
processes of the occipital bane, from the pterygoid processes of
the os sphenoides, and from the upper and lower jaws, near
the last dentes molares, on each side. They unite in a middle
line in the back of the pharynx.

The fibres of the middle muscles originate principally from
the lateral parts of the os hyoides, and from the ligaments
which connect that bone to the thyroid cartilage. The supe-
rior fibres run obliquely upwards, so as to cover a part of the
first mentioned muscle, and terminate in the cuneiform process
of the occipital bone ; while the other fibres unite with those of
the opposite side in the middle line.

The fibres of the lower muscles arise from the thyroid and
the cricoid cartilages, and terminate also in the middle line :
those which are superior, running obliquely upwards ; the
inferior, nearly in a transverse direction.

It is obvious, from the origin and insertion of these fibres,
that the pharynx must have the power of contracting its
dimensions in every respect ; and, particularly, that its diameter
may be lessened at any place, and that the whole may be
drawn upwards.

PART VI.
OF THE THORAX.

BEFORE the thorax is described, it will be in order to con-
sider the

Mamma ;

Or those glandular bodies situated on the anterior part of it,
which, in females, are destined to the secretion of milk.

These glands lie between the skin and the pectoral muscles,
and are attached to the surfaces of those muscles by cellular
membrane.

They are of a circular form ; and consist of a whitish firm
substance, divisible into small masses or lobes, which are com-
posed of smaller portions or lobuli. Between these glandular
portions, a great deal of adipose matter is so diffused, that it
constitutes a considerable part of the bulk of the mammae.

The gland, however, varies greatly in thickness in the same
person at different periods of life.

The mammae become much enlarged about the age of pu-
berty. They are also very large during pregnancy and lacta-
tion ; but after the period of child-bearing they diminish con-
siderably. They are supplied with blood by the external and
internal mammary arteries, the branches of which enter them
irregularly in several different places.

The veins correspond with the arteries.

From the small glandular portions that compose the mamma,
fine excretory tubes arise, which unite together and form the
great lactiferous ducts of the gland. These ducts proceed in a
42

494 MAMM2E.

radiated manner from the circumference to the centre, and
terminate on the surface of the nipple.*

They are commonly about fifteen in number, and vary con-
siderably in size : the largest of them being more than one-sixth
of an inch in diameter.f

Fig. 126.J

They can be very readily injected by the orifices of the nip-
ple from a pipe filled with mercury, in subjects who have died
during lactation or pregnancy ; but they are very small in sub-
jects of a different description.

It has been asserted by respectable anatomists, that these
ducts communicate freely with each other; but they do not
appear to do so ; each duct seems to be connected with its pro-
per branches only.<$>

* Described in the 10th century, by Charles Etienne, Vesalius and Posthius,
but their uses were unknown. — H.

f These ducts vary in number in different individuals, from fifteen to
twenty. — p.

$ Fig. 126, is a vertical section of the mammary gland of a young female
who died during lactation. The ducts were injected with wax, and two dissected
out their full length to their origin in the lobules of the gland. 2, 2, Base of
the nipple. 3, 3, 3, Lactiferous ducts cut off at the base of the nipple. 4, 4,
The top of the ducts exhibited their whole length. 5, 5, Sinuses formed by
these ducts at the base of the nipple. 6, 6, 6, 6, Branches of these ducts
running to the lobules. 7, 7, 7, 7, 7, The lobules separated from each other.
8, 8, The orifices of these ducts on the top of the nipple.

§ See Edinburgh Medical Commentaries, vol. i. p. 31. — A paper by Meckel.

LACTIFEROUS DUCTS. 495

Haller appears to have entertained the remarkable senti-
ment, that some of the ducts originate in the adipose matter
about the gland, as well as in the glandular substance.* >

The papilla, or nipple, in which these ducts terminate, is in
the centre of the mamma : it consists of a firm elastic substance,
and is nearly cylindrical in form. It is rendered tumid by
irritation, and by certain emotions.

— This power of erectibility of the nipple is due to the presence
of some contractile tissue in its composition analogous to the
dartus structure of the scrotum. There is now believed to be no
erectile tissue in its composition. —

The lactiferous ducts terminate upon its extremity. When
it is elongated they can freely discharge their contents ; but
when it contracts, this discharge is impeded. The skin imme-
diately around the nipple is of a bright red color in virgins of
mature age. In pregnant women it is sometimes almost black ;
and in women who have borne children it is often brownish.
It abounds with sebaceous glands, which form small eminences
on its surface.

— During gestation these follicles or glands are much increased
in size, so as to become in consequence of this enlargement, one
of the most certain signs of pregnancy. During suckling they
are still farther enlarged, so as to appear like small pimples
projecting from the skin, and serve by the increased secretion
they throw out, to defend the nipple and areola, from the
excoriating action of the saliva of the child. —

This gland exists in males, although it is very small. In
boys, soon after birth, it has often been known to tumefy, and
become very painful, in consequence of the secretion and accu-
mulation of a whitish fluid, which can be discharged by pres-
sure. It also sometimes swells and is painful, in males at the
age of puberty.

* Elementa Physiologiae, Tom. 7, Pars II. page 7. — In the adipose matter
about the gland, the lactiferous tubes (ducti gdlactophori) appear to communi-
cate with the absorbent vessels. In injecting the gland with mercury, I have
frequently found the metal to pass off from the ducts along the absorbent
vessels. — p.

496 LACTIFEROUS DUCTS.

There have been some instances in which it has secreted
milk in adult males ; and a few instances also in which it has
been affected with cancer, in the same sex.

The mamma is plentifully supplied with absorbent vessels,
which pass from it to the lymphatic glands in the axilla.

Its nerves are principally derived from the great plexus
formed by the nerves of the, arm.

— The skin covering the mammary gland, is exceedingly
thin, delicate and vascular, and that of the nipple and areola,
more delicate and sensitive than any other portion.
— Each lactiferous duct by its branching and convolutions,
forms a distinct lobule of the gland, and terminates in a series
of vascular granules* the ultimate caecal termination of the ducts
about the size of a millet seed, which are readily distinguished
from each other in individuals who have died during lactation.
The lobules of the gland vary in size, which, in subjects where
the subcutaneous matter is not abundant, gives a feeling of un-
evenness or roughness to the gland.
— There are no valves in the lactiferous tubes. —

* Histoire de la Generation, par Grimaud de Caux et Martin Saint- Ange,
4to. Paris, 1837.— p.

CAVITY OF THE THORAX. 497

CHAPTER XV.

OF THE GENERAL CAVITY OF THE THORAX.

Of the Form of the Cavity of the Thorax.

THE osseous structure of the thorax is described in page
155. The cavity is completed by the intercostal muscles, which
close the vacuities between the ribs ; and by the diaphragm,
which fill up the whole space included within its lower
margin.

If we except the apertures of the diaphragm, which are
completely occupied by the aorta, the vena cava, and the oeso-
phagus, &c., the only outlet of this cavity is above : it is formed
by the upper ribs, the first dorsal vertebra, and the sternum.
The figure of this aperture is between that of the circle and
the oval ; but it is made irregular by the vertebrae, and by the
upper edge of the sternum.

When the superior extremities and the muscles appropriated
to them are removed, the external figure of the thorax is coni-
cal ; but the cavity formed by it is considerably influenced by
the spine, which protrudes into it ; while the ribs, as they pro-
ceed from the spine, curve backwards, and thus increase the
prominency of the cavity.

The diaphragm has a great effect upon the figure of the
cavity of the thorax. It protrudes into it from below, with a
convexity of such form that it has been compared to an inver-
ted bowl ; so that although it arises from the lower margin of
the thorax, the central parts of it are nearly as high as the
fourth rib.

The position of the diaphragm is also oblique. The anterior
portion of its margin, being'connected to the seventh and eighth
ribs, is much higher than the posterior portion, which is.attached
to the eleventh and twelfth.

In consequence of the figure and position of the diaphragm,
42*

498 PLEURJE.

the form of the cavity of the thorax resembles that of the hoof
of the ox when its posterior part is presented forwards.

Of the Arrangement of the Pleura.

The thorax contains the two lungs and the heart, as well as
several very important parts of smaller size.

The lungs occupy the greatest part of the cavity ; ana to
each of them is appointed a complete sac, called Pleura, which
is so arranged that it covers the surface of the lungs, and is
continued from it to the contiguous surface of the thorax,
which it lines. After covering the lung, it is extended from it
to the spine posteriorly : so that in tracing the pleura in a
circular direction, if you begin at the sternum, it proceeds on
the inside of the ribs, to the spine ; at the spine it leaves the
surface of the thorax, and proceeds directly forwards towards
the sternum. In its course from the spine to the sternum, it soon
meets with the great branch of the windpipe and blood-vessels,
which go to the lung : it continues on these vessels and round
the lung until it arrives at the anterior side of the vessels, when
it again proceeds forwards until it arrives at the sternum. Each
sac being arranged in the same way, there is a part of each
extended from the spine to the sternum. These two laminae
form the great vertical septum of the thorax, called Medias-
tinum. They are situated at some distance from each other;
and the heart, with its investing membrane or pericardium, is
placed between them.

The pericardium is also a complete sac or bladder, which,
after covering perfectly the surface of the heart, is extended
from it so as to form a sac, which lies loose about it, and
appears to contain it. This loose portion adheres to those parts
of the laminae of the mediastinum, with which it is contiguous ;
and thus three chambers are formed within the cavity of the
thorax: one for each lung, and one for the heart.

The two laminae of the pleura, which constitute the mediasti-
num, are at different distances from each other, in different
places. At the upper part of the thorax, they approach each
other from the internal edges of the first ribs ; and as these

MEDIASTINUM. 499

include a space which is nearly circular, the vacuity between
these laminae is necessarily of that form, at its commencement
above.

Here, therefore, is a space between them above, (Superior
Mediastinum) which is occupied by the transverse vein that
carries the blood of the left subclavian and the left internal
jugular to the superior cava ; by the trachea ; by the oesopha-
gus ; and by the subclavian and carotid arteries, as they rise
from the curve of the aorta. This space is bounded below by
the above mentioned curve of the aorta.

The heart and pericardium are so placed that there is a
small distance between them and the sternum : in this space
the two laminae of the mediastinum are very near to each
other ; and cellular substance intervenes between them. This
portion of the mediastinum is called the Anterior Medias-
tinum.*

Posteriorly, the heart and pericardium are also at a small
distance from the spine ; and here the lamina of the mediasti-
num are at a greater distance from each other, and form a
long narrow cavity which extends down the thorax in front of
the vertebrae : this is called the Posterior Mediastinum. It
contains a considerable portion of the aorta as it descends from
its curve, the oesophagus, the thoracic duct, and the vena azygos.
The aorta is in contact with the left lamen, and can often be
seen, through it when the left lung is lifted up.
— The posterior and anterior mediastina are separated from
each other by the pericardium which encloses the heart. But as
the serous layers of the anterior, are reflected one on each side
of the pericardium, to meet the posterior mediastinum, it
appears to -me to render the study of this part more easy, to

* This mediastinum, being placed in front of the longitudinal diameter of
the pericardium is found at its lower part inclined to the left of the middle line.
The cellular tissue between its layers, communicates indirectly with the cellular
tissue on the outer side of the peritoneum, in the notch formed by the origin of
the greater muscle of the diaphragm, under the xiphoid appendix of the
sternum. By this channel, abscesses of the anterior mediastinum, may make
their way externally upon the abdomen. — p.

500 PREPARATION OF THE THORAX.

•

consider that embracing the pericardium as a middle medias-
tinum.

The oesophagus is in contact with the right lamen ; in its
progress downwards, it inclines to the left side and is advanced
before the aorta.

The vena azygos appears posterior to the oesophagus ; it
proceeds upwards until it is as high as the right branch of the
windpipe : here it bends forward, round that branch, and opens
into the superior cava, laefore that vein opens into the right
auricle.

The thoracic duct proceeds upwards from below, lying in the
space between the aorta and the vena azygos, until the begin-
ning of the curve of the aorta, when it inclines to the left, pro-
ceeding towards the place of its termination.

— The anterior and posterior mediastina are formed as is
shown above, by the layers of the pleura, between the sternum
and pericardium, and between the pericardium and spine.
But the pericardium does not extend the whole length of the
thoracic cavity ; it terminates about two inches short of the top
of the sternum, and at this part, there being nothing interposed
to divide the layers into an anterior and posterior portion, they
pass directly from the vertebrae to the sternum, and constitute
what is called the Superior Mediastinum. The two layers con-
stituting this, continuous below with the anterior and superior
mediastina, and each lining the upper margin of the first rib, so
as to form a conical pouch projecting a slight distance above
the middle of the clavicle, constitute a triangular cavity, the
base of which is upwards, and corresponds to the root of the
neck. This cavity contains the thymus gland, the arteria
innominata, the primitive carotid and subclavian of the left side,
the superior vena cava, the trachea, oesophagus, and par vagum
nerves.

— The sympathetic nerve is not contained in this mediastinum ;
it passes a little to the "outside of the posterior external angle
of it.—

The formation of the mediastinum, and the arrangement of the pleura, as well
as the connexion of these membranes with the parts contained in the thorax,

PREPARATION OF THE THORAX. 501

may be studied advantageously, after the subject has been prepared in the
manner now to be described.

Take away, from each side, the five ribs which are situated between the first
and last true ribs, by separating their cartilages from the sternum, alfd their
heads from the spine ; so that the great cavities of the thorax majf be laid
open.

The precise course of the mediastinum is thus rendered obvious; and the
sternum may now be divided with a saw throughout its whole length in the
same direction j so that the division of the bone may correspond with the
space between the lamina of the mediastinum.

Separate the portion of the sternum cautiously, so as to avoid lacerating the
lamina of mediastinum ; and to keep them separate, while the trachea is
dissected from the neck into the cavity of the thorax ; the great transverse
vein and the descending cava are dissected to the pericardium ; and the left
carotid artery, with the right subclavian and carotid, are dissected to the curve
of the aorta, taking care not to destroy the lamina of the mediastinum.

After this preparation the upper space between the lamina of the mediastinum
can be examined, and the relative situation of the trachea and the great
vessels in it can be understood. The anterior mediastinum can also be
studied : the root of each lung, or its connexion with the mediastinum, may
be seen perfectly ; and the precise situation of the lung, in its proper cavity,
may be well conceived.

After this, while the portions of the sternum are separated, the pericardium
may be opened, and the heart brought into view : the attachment of the
pericardium, and to the mediastinum, and to the diaphragm, may be seen
with advantage in this situation. The portions of the sternum may now be
detached from the ribs, with which they remain connected ; and further dis-
section may be performed to examine the posterior mediastinum and Us con-
tents, and the parts which constitute the roots of the lungs.

502 THE PERICARDIUM.

CHAPTER XVI.

-

OF THE HEART AND PERICARDIUM, AND THE GREAT VESSELS
CONNECTED WITH THE HEART.

Of the Pericardium.

THE heart is enclosed by a membranous sac, which, upon a
superficial view, seems only connected with its great vessels.

— The whole of the organ lays unattached in the cavity of
the sac, except, by the arteries and veins connected with its
base. The sac is in fact composed of two layers, one external
and fibrous, and one internal and serous ; the latter of these not
only lines the inner face of the outer membrane, but is reflected
like other serous membranes, over the roots of the vessels
placed in the pericardium, and over the whole of the outer sur-
face of the heart itself. This internal serous lining is very thin
and delicate, and can only be raised in small shreds, either
rom the outer layer of the pericardium, or from the heart ;
except at the base of the latter organ, where, in females, it is
usually, and in males, frequently, separated from the muscular
tissue, by some sub-serous fatty matter. —

If it were dissected from the heart, without laceration or
wounding, it would be an entire sac.

The pericardium, thus arranged, is placed between the two
lamina of the mediastinum, and adheres firmly to them where
they are contiguous to it ; it also adheres firmly to the dia-
phragm below, and thus preserves the heart in its proper
position.

The figure of the pericardium, when it is distended, is some-
what conical ; the base being on the diaphragm. The cavity
formed by it is larger than the heart after death, but it is
probable, that the heart nearly fills it during life ; for when this

THE PERICARDIUM. 503

organ is distended by injection, it often occupies the whole cavity
of the pericardium.

— The attachment of the pericardium to the diaphragm, is
exactly over the cordiform tendon of the latter. The French
anatomists have erroneously considered the fibrous layer of the
pericardium, as a mere reflection of the tendon upwards. By
separating them with a knife, we find, they are united by a
short cellular tissue, which is densest and strongest at the peri-
phery of their junction. The sides of the pericardium are
covered in part by the pleura, which gives the sac the appear-
ance of being formed by three tunics.

— Underneath the pleural lining, is found the phrenic nerve,
and in fat subjects, a good deal of adipose matter. —

The pericardium is composed of two lamina, the internal of
which covers the heart, as has been already described ; while
the external merely extends over the loose portion of the other,
and blends itself with the mediastinum, where that membrane
invests the great vessels.

— Its principal attachment or termination above, is upon the
arteries and veins entering the heart, (with the exception of the
vena cava inferior,) over which it sends tubular prolongations,
which gradually blend with their external coats. Between these
prolongations on the inside of the sac, hollow pouches are
necessarily left, which are called the cornua of the pericardium.
— The fibrous layer of the pericardium resembles in structure
and appearance, the dura mater of the brain.
— The arteries of the pericardium are very small ; they are de-
rived from the phrenic, bronchial, cesophageal, internal mam-
mary arteries, and from the aorta itself. Its veins terminate in
the vena azygos. Its nerves are few and small, and originate
from the cardiac plexus. — -

The internal surface of the pericardium is very smooth and
polished ; and in the living subject is constantly moistened with
a fluid which is probably effused from the exhalent vessels on
its surface.

The quantity of this fluid does not commonly exceed two
drachms ; but in cases of disease it sometimes amounts to

504 THE HEART.

many ounces.* It is naturally transparent, but slightly tinged
with red in children, and yellow in old persons. It is often
slightly tinged with red in persons who have died by violence.

Of the Heart.

The great organ of the circulation consists of muscular
fibres, which are so arranged that they give it a conical form,
and compose four distinct cavities within it.

Two of these cavities, which are called Auricles, receive the
contents of the veins ; the other two communicate with the
arteries, and are called Ventricles.

The auricles form the basis of the cone ; the ventricles the
body and apex.

The structure of the auricles is much less firm than that of
the ventricles, and consists of a smaller proportion of muscular
fibres. They appear like appendages of the heart, while the
ventricles compose the body of the viscus.

The ventricles are very thick, and are composed of muscular
fibres closely compacted.

The figure of the heart is not regularly conical ; for a portion
of it, extending from the apex to the base, is flattened ; and
in its natural position, this flat part of the surface is down-
wards.

It is placed obliquely in the body ; so that its base presents
backward and to the right, and its apex forward and to the
left.

Notwithstanding this obliquity, the terms right and left are
applied to the different sides of the heart, and to the different
auricles and ventricles ; although they might, with equal pro-
priety, be called anterior and posterior.

/ The two great veins called Vena Cavce, which bring the

blood from every part of the body, open into the right auricle

\ from above and below ; the right auricle opens into the right

* The pericardium has been so distended, by effusion in dropsy, that it has
formed a tumour, protruding on the neck from under the sternum. This
tumour had a strong pulsating motion. It disappeared completely when the
other hydropic symptoms were relieved.

RIGHT AURICLE.

505

ventricle; and from this ventricle arises the artery denomi-
nated Pulmonary, which passes to the lungs.

The Pulmonary veins, which bring back the bloody from
the lungs, open into the left auricle ; this auricle opens into the
left ventricle ; and from this ventricle proceeds the Aorta,
or great artery, which carries blood to every part of the
body.

The heart is preserved in its position, 1st, by the venae cavae
which are connected to all the parts with which they are con-
tiguous in their course ; 2d, by the vessels which pass between
it and the lungs, which are retained in a particular position by
the mediastinum ; 3d, by the aorta, which is attached to the
mediastinum in its course downwards, after making its great
curve ; and 4th, by the pericardium, which is attached to the
great vessels and to the mediastinum. By these different
modes the basis of the heart is fixed, while its body and apex
are perfectly free from attachment, and only contiguous to the
pericardium.

The external surface of the
heart, being formed by the serous
layer of the pericardium, is very
smooth : under this surface a
large quantity of fat is often
found.

The two auricles are contigu-
ous to each other at the base,
and are separated by a partition
which is common to both.

The Right Auricle originates
from the junction of the two
venae cavae. These veins are
U united at some distance behind

Fig.

* Longitudinal section of the heart, showing its cavities. *, Right ventri-
cle, c, Septum ventriculorum. d, Right auricle, e, Left auricle. /, Section
of the mitral valves, g, Section of tricuspid valves, h, Arch of aorta. A,
Descending aorta, i, i, Vena cava superior and inferior, k, k, Right and left
branches of the pulmonary artery. I, I, Pulmonary veins.
43

506

RIGHT AURICLE.

the right* ventricle, and are dilated anteriorly into a sac or
pouch, which is called the Sinus, and extends to the right ven-
tricle, to which it is united.f

The upper part of this pouch, or sinus, forms a point with
indented edges, which is detached from the ventricle, but lies
loose on the right side of the aorta. This point has some
resemblance to the ear of a. dog, from which circumstance the
whole cavity has been called auricle ; but by many persons
the cavity is considered as consisting of two portions : the
Auricle, strictly speaking ; and the Sinus Venosus, above
described : they however form but one cavity.

This portion of the heart, or Right Auricle, is of an irregular
oblong figure. In its posterior surface, it is indented ; for the
direction of the two cavae, at their junction, is not precisely the
same; but they form an angle, which causes this indentation.
The anterior portion of the auricle, or that which appears like
a pouch between the ventricle and the veins, is different in its
structure from the posterior part, which is strictly a portion of
the veins. It consists simply of muscular fibres, which are
arranged in fasciculi that cover the whole internal surface : this
is also the case with the point, or that part which is strictly
called auricle.

These fasciculi are denominated Musculi Pectinati, from
their resemblance to the teeth of a comb.

That part of the internal surface, which is formed by the
septum is smooth, and the whole is covered by a delicate mem-
brane.

On the surface of the septum, below the middle, is an oval
depression, which has a thick edge or margin: this is called
the Fossa Ovalis.^ In the foetal heart, it was the Foramen
Ovale, or aperture which forms the communication between
the two auricles.

* In this description the heart is supposed to be in its natural position.

•}• At the place of junction of these veins there is a projection, indistinctly
seen in man, but very manifest in some of the larger mammalia, called tuber-
culum Loweri. — P.

:£ The thick edge or margin is spoken of as the annulus ovalis. — P.

RIGHT AURICLE. 507

Near this fossa is a large semilunar plait, or valve, with its
points and concave edge uppermost, and convex edge down-
wards. It was described by Eustachius, and therefore, is
called the Valve of Eustachius.

— It commences at the lower surface of the opening of the
inferior vena cava, and runs forwards to terminate below the
fossa ovalis. It served in the foetus to obstruct the passage
of the venous blood from the right auricle into the right ven-
tricle, and to direct it in a great measure through the foramen
ovale. —

Anterior to this valve, and near the union of the auricle and
ventricle, is the orifice of the proper vein of the heart, or the
coronary vein. This orifice is covered by another semilunar
valve, which is sometimes reticulated.*

The aperture, which forms the communication between the
right auricle and right ventricle, is about an inch in diameter,
and is called ostium venosum. From its whole margin arises
a valvular ring, or duplicature of the membrane lining the
surface : this circular valve is divided into three angular por-
tions, which are called Valvula Tricuspides. From their
margins proceed a great number of fine tendinous threads,
which are connected to a number of distinct portions of mus-
cular substance, which arise from the ventricle.

The Right Ventricle, when examined separately from the
other parts of the heart, is rather triangular in its figure, It is
composed entirely of muscular fibres closely compacted ; and
is much thicker than the auricle, although not so thick as the
other ventricle. Its internal surface is composed of bundles or
columns of fleshy fibres, which are of various thickness and
length. Some of these columns (columna carne<z) arise from
the ventricle, and are connected with the tendinous threads,
(chorda tendinea?) which are attached to the margin of the
tricuspid valves : the direction of them is from the apex of the

* The orifice is called the foramen Thebesii, and the valve valvula Thebesii,
from the anatomist who first described them.

There are several other orifices in the neighborhood of the foramen of The-
besius, by which some of the lesser coronary veins discharge into the right
auricle. — p.

508

RIGHT VENTRICLE.

heart towards the base. Others of the columns arise from one
part of the surface of the ventricle, and are inserted into another
part. A third species are attached to the ventricle throughout
their whole length, forming ridges or eminences on it. The
columns of the two last described species are very numerous.
They present an elegant reticulated surface when the ventricle
is laid open, and appear also to occupy a considerable portion
of the cavity of the heart, which some of them run across in
every direction near the apex. They are all covered by a
membrane continued from the auricle and the tricuspid valves ;
but this membrane appears more delicate and transparent in
the ventricle than it is in the auricle.

— This is called the internal serous, or endo-cardial lining
membrane of the heart. On the right side it is continuous with
that of the veins and pulmonary artery, on the left with the
aorta and pulmonary veins. It is extremely thin, smooth, and
transparent, covers all the interior surface of the cavities of the
heart, and by being thrown into folds, with some fibrous matter
interposed between the layers to increase their strength, con-
stitutes the valves. —

A portion of the internal surface of the ventricle, which is to
the left, is much smoother and less fasciculated than the rest :
it leads to the orifice of the pulmonary artery, which arises
from it near the basis of the ventricle. This artery is very
conspicuous, externally, at the basis of the heart.

It is very evident, upon the first inspection of the heart, that
the valvulse tricuspides will permit the blood to flow from the
auricle to the ventricle ; but must rise and close the orifice, and
thereby prevent its passage back again, when the ventricle
contracts.

The use of the tendinous threads, which connect the valves
to the fleshy columns, is also very evident ; the valve is sup-
ported by this connexion, and prevented from yielding to the
pressure and opening a passage into the auricle. The blood,
therefore, upon the contraction of the ventricle, is necessarily
forced into the pulmonary artery ; the passage to which is now
perfectly free. In this artery the membrane lining the ventricle

LEFT AURICLE. 509

seems continued ; but immediately within the orifice of the
artery, it is formed into three semicircular folds, each of which
adheres to the surface of the artery by its circumference, while
the edge constituting its diameter is loose. In the middle of
this loose edge is a small firm tubercle, called Corpusculum
Arantii* which adds to the strength of the valve. Each of
these valves, by its connexion with the artery, forms a sac or
pocket, the orifice of which opens forward towards the course
of the artery, and the bottom of it presents towards the ventricle.
Blood will, therefore, pass from the ventricle in the artery, and
along it without filling these sacs ; and, on the contrary, in this
course, will compress them and keep them empty. If it moves
in the artery towards the heart, it will necessarily fill these
sacs, and press the semicircular portions, from the sides of the
artery, against each other ; by this means a partition or septum,
consisting of three portions, will, be formed between the
artery and the heart, which will always exist when the
artery compresses, (or acts upon,) its contents. It is demon-
strable, by injecting wax into the artery, in a retrogade
direction, that these valves do not form a flat septum, but one
which is convex towards the heart, and concave towards the
artery ; and that this convexity is composed of three distinct
parts, each of which is convex. At the place where these
valves are fixed, the artery bulges out when extended by a
retrogade injection. The enlargements thus produced are
called the Sinuses of Valsalva, after the anatomist who first
described them. The valves are called Semilunar — and,
although they are formed by a very thin membrane, they are
very strong.

The Left Auricle is situated on the left side of the basis of
the heart. It originates from the junction of the four pulmo-
nary veins ; two of which come from each side of the thorax,
and appear to form a large part of it. It is nearly of a cubic
form: but has also an angular portion, which constitutes the
proper auricle, that proceeds from the upper and left part of

* After Arantius, a professor at Bologna, who first described it.
43*

510 LEFT VENTRICLE.

the cavity, and is situated on the left side of the pulmonary
artery.

This auricle is lined by a small membrane, from which the
valves between it and the ventricle originate ; but it has no
fleshy columns or musculi pectinati, except in the angular pro-
cess properly called auricle.

These valves and the ^orifice communicating with the
ventricle, resemble those which have been already described
between the right auricle and ventricle : but with this differ-
ence, that the valvular ring is divided into two portions only,
instead of three which are called Valvula Mitrales.* The
tendinous threads, which are connected to the muscular
columns, are also attached to these valves, as in the case of the
right auricle.

These valves admit the passage of blood from the auricle into
the ventricle, but completely prevent its return when the
ventricle contracts. One of them is so situated that it covers
the mouth of the aorta while the blood is flowing into the ven-
tricle, and leaves that orifice open when the ventricle contracts,
and the passage to the auricle is closed.

The Left Ventricle is situated posteriorly, and to the left of
the Right Ventricle. Its figure is different, for it is rather coni-
cal, and it is also longer.

The internal surface of this ventricle resembles that of the
right ventricle : but the columnae carneae are stronger and
larger.

On the right side of this ventricle is the mouth of the aorta.
The surface of the ventricle near this opening is smooth and
polished, to facilitate the passage of the blood.

The mouth of the aorta is furnished with three semilunar
valves, after the manner of the pulmonary artery, but the
former are stronger ; the corpuscula Arantii are better developed
in them. Indeed, Mr. Hunter does not admit of their existence
in the pulmonary artery. The sinuses of Valsalva are about the
same size m both arteries.

* From a resemblance in shape to the mitre or bishop's cap. — P.

FIBRES OF THE HEART. 511

The cavity of this ventricle is supposed to be smaller than
that of the right : but the amount of the difference has not been
accurately ascertained. j

This ventricle must have much more force than the right, as
its parietes are so much thicker. Their thickness often exceeds
half an inch.

The difference in the strength of the two ventricles probably
corresponds with the difference between the extent of the pul-
monary artery and the aorta.

The thickness of the septum between the ventricles is thicker
than the sides of the parietes of the right ventricle, and less
thick than those of the left.

The muscular fibres of the heart are generally less florid
than those of the voluntary muscles ; they are also more
closely compacted together. The direction of many of them is
oblique or spiral ; but this general arrangement is very intricate :
it is such, however, that the cavities of the heart are lessened,
and probably completely obliterated, by the contraction of
these fibres.*

— The muscular fibres of the heart have been carefully stu-
died by Wolf and Malpighi, and more recently still, by Mr.
Searlef and M. Gerdy.J According to this latter anatomist,
there is a fibrous zone or girdle formed around each auricle
and arterial orifice of the heart, which zones are connected
with each other and with the valves. From these zones origi-
nate all the muscular fibres of the heart. Some which run
upwards and turn in every direction round the auricles, and
form loops, the extremities of which are inserted on the oppo-
site sides of the zone. Others which run downwards and em-
brace the ventricles, are also inserted on the opposite sides
of the same zone, or that which surrounds the orifices of the
aorta or pulmonary artery. The structure of the ventricular

* Mr. Home has given a precise description of the muscular fibres of the
heart in his Croonian Lecture. London Philosophical Transactions for 1795,
part I. page 215.

f Cyclopedia of Anntomy and Physiology. London. — Article — Fibres of
the heart, of which he has given a minute and lengthened description.

\ Journal Complementaire du Diet, des Scienc. Med. torn. ix. p. 97. —

512 CORONARY VESSELS.

fibres is most complicated. They are first superficially placed,
and as they make their spiral turns, sink deep into the sub-
stance of the heart, somewhat like the contours of a leaf of
paper rolled into the form of a cone. They consist of fibres
proper to each ventricle, and fibres common to both. The
former, after arising from the zone, turn spirally around the
axis of the ventricle, so as to form many times the figure of 8,
and coming upon the anterior face of the same side, terminate
upon the zone surrounding the arterial orifice. The fibres
common to the ventricles are of two kinds — superficial and
deep-seated. The superficial are divided into anterior and
posterior. The anterior arising from the anterior part of the arte-
rial and auricular zones, run obliquely downwards and to the
left, converging towards the apex of the heart ; these are rolled
around the axis of the left ventricle, and dip inwards to termi-
nate in, or form the columnae carnese. The superficial part of
this order of fibres, is common to both ventricles ; the deep-
seated part belongs to the left only. The posterior superficial
fibres arise behind from the auricular zones only, and run
downwards, so as to embrace the right border of the heart,
come in front of the heart and opposite to the septum ventri-
culorum, dip under the anterior superficial fibres, wind round
the axis of the right ventricle and terminate in its columnae
carnese. These also in part only, are common to both ven
tricles.

— The deep-seated fibres form the internal part of the walls of
the right ventricle. They arise from the fibrous zones of the
right side. The anterior portion of these fibres runs obliquely
downwards, and backwards to the septum ; the posterior and
internal, pass at once into the septum, roll themselves round the
left ventricle and are lost amidst the other fibres. Thus it
appears, that by removing the superficial layer of the common
stratum, the heart may be divided into lateral halves, each con-
sisting of two muscular sacs, an auricle and ventricle, adjoined
to those of the opposite side in the middle line. —

The external surface of the heart is covered by that portion
of the pericardium which adheres to it. Adipose matter is often

VESSELS AND NERVES OF THE HEART. 513

deposited between this membrane and the muscular surface;
being distributed irregularly in various places.

This membrane is continued from the surface of the ventricles
over that of the auricles. When it is dissected off from the
place of their junction, these surfaces appear very distinct from
each other.

The proper blood-vessels of the heart appear to be arranged
in conformity to the general laws of the circulation, and are
very conspicuous on the surface. There are two arteries
which arise from the aorta immediately after it leaves the heart,
so that their orifices are covered by two of the semilunar
valves. One of these passes from the aorta between the pulmo-
nary artery and the right auricle, and continues in a circular
course in the groove between the right auricle and the right
ventricle, and sends off its principal branches to the right side
of the heart.

The other artery of the heart passes between the pulmonary
artery and the left auricle. It divides into two branches ; one,
which is anterior, passes to a groove on the surface, corres-
ponding to the septum between the two ventricles, and con-
tinues on it to the apex of the heart, sending off branches in
its course ; another, which is posterior and circumflex, passes
between the left auricle and ventricle.

The great vein of the heart opens into the under side of the
right auricle, as has been already mentioned : the main trunk
of this vein passes for some distance between the left auricle
and ventricle.*

* It was asserted by Vicussens, at an early period in the last century, and
soon afterwards by Thebesius, a German Professor, that there were a number
of small orifices in the texture of the heart, which opened into the different
cavities on both sides of it.

This assertion of a fact so difficult to reconcile with the general principles of
the circulation, was received with great hesitation : and although it was con-
firmed by some very respectable anatomists of the last century, it was denied
by others. Some of the anatomists of the present day have denied the existence
of these orifices, and some others have neglected them entirely.

The subject was brought forward in the London Philosophical Transactions
of 1798, Part I. by a very respectable anatomist, Mr. Abernethy, who states
that he has often passed a coarse waxen injection from the proper arteries and

514 GREAT VESSELS OF THE HEART.

From the course of these different vessels round the basis of
the ventricles of the heart, they are generally called Coronary
Vessels : the arteries are denominated, from their position, Right
and Left Coronary.

The nerves of the heart come from the cardiac plexus, which
is composed of threads derived from the intercostal or great
sympathetic nerves, and the nerves of the eighth pair.

Of the Aorta, the Pulmonary Artery and Veins, and the
Venae, Cava ; at their commencement.

The two great arteries, which arise from the heart, commence
abruptly, and appear to be extremely different in their composi-
tion and structue from the heart.

They are composed of a substance, which has a whitish
color, and very dense texture, and is very elastic as well as
firm and strong.

When the pericardium is removed, these arteries appear to
proceed together from the upper part of the basis of the heart :
the pulmonary artery being placed to the left of the aorta with
the left auricle on the left side of it, and the right auricle on
the right side of the aorta. The pulmonary artery arises from
the most anterior and left part of the basis of the right ven-
tricle, and proceeds obliquely backwards and upwards ;
inclining gradually to the left side for about eighteen or
twenty lines ; when it divides into two branches which pass to
the two lungs.

The aorta arises from the left ventricle, under the origin of

veins of the heart into all the cavities of that organ, and particularly into the
Left Ventricle. But it mas only in subjects with diseased lungs that this was
practicable.

The existence of this communication between the coronary vessels and the
great cavities of the heart seems therefore to be proved. The easy demonstra-
tion of such subjects is ingeniously referred by Mr. Abernethy, to the obstruc-
tion of the circulation in the lungs ; and he regards the communication as a
provision enabling the coronary vessels to unload themselves, when the coronary
vein cannot discharge freely into the right* auricle.*

* This assertion of Mr. Abernethy 's, has not been confirmed by subsequent investigations,
except incases where the tissue of the heart was softened, and its vessels had been ruptured
by the force of the injection, p.

GREAT VESSELS OF THE HEART. 515

the pulmonary artery, and immediately proceeds to the right,
covered by that vessel, until it mounts up between it and the
right auricle : it then forms a great curve, or arch, which/ turns
backward and to the left, to a considerable distance beyond the
pulmonary artery. In this course, it crosses the right branch of
the pulmonary artery ; and, turning down in the angle between
it and the left branch, takes a position on the left side of the
spine.

Fig. 128.*

The course of this artery, from its commencement at the ven-
tricle, to the end of the great curve or arch, is extremely varied.
The uppermost part of the curve is in the bottom of the

* a, Left ventricle, b, Right ventricle, c, Right auricle. The left auricle
is seen above the left ventricle of the same side, d, Vena cava inferior, e,
Subclavian and jugular veins j those of the left side unite to form the vena
transversa ; those of the right, to form the vena innominata ; the junction of
these larger trunks, constitutes the vena cava superior or descendens. /, Left
carotid, g, Left subclavian artery, arising from the arch of the aorta, h, De-
scending aorta, z, k, Right subclavian, and right carotid, given off from the
arteria innominata, which is seen arising from the arch of the aorta. I, Pul-
monary artery, dividing into two branches, one for each lung — the left passing
in front of the descending aorta, the right, behind the aorta, where it begins to
form the curve, m, Vena cava superior, n, Aorta, o, Left pulmonary veins,
entering auricle of same side. The right pulmonary veins, are seen on the
opposite side, p, p, Lungs, t, Trachea. — p.

516 VEN^E CAVJE.

chamber formed by the separation of the lamina of the medias-
tinum when they join the first rib on each side.

From this part of the curve three large branches go off,
namely, one, which soon divides into the carotid and the sub-
clavian arteries of the right side ; a second, somewhat smaller,
which is the left carotid ; and a third, which is the left subclavian
artery.

When the heart and its great vessels are viewed from be-
hind, (after they have all been filled with injection ; and the
pericardium, mediastinum, and windpipe have been removed,)
the aorta appears first, descending behind the other vessels ; the
pulmonary artery then appears, dividing so as to form an obtuse
angle with its two great branches, each of which divides again
before it enters the lung to which it is destined.

Under the main trunk of the pulmonary artery is the left
auricle : its posterior surface is nearly of a square form, and
each of the pulmonary veins proceeds from one of its angles.
These veins ramify in the substance of the lungs, at a very
short distance from the auricle : the two uppermost of them are
situated rather anterior to the branches of the pulmonary
artery.

In this posterior view, the pulmonary vessels of the right side
cover a great part of the right auricle, as it is anterior to them.
The lower portion of the auricle, with the termination of the
inferior cava, is to be seen below them. Above them the supe-
rior cava appears ; and in that part of it which is immediately
above the right branch of the pulmonary artery, is the orifice of
the vena azygos.

In its natural situation in the thorax, the superior cava is
connected by cellular membrane to the right lamen of the
mediastinum, and is supported by it. At a small distance
below the upper edge of the sternum, it receives the trunk
formed by the left subclavian and internal jugular vein, which
passes obliquely across the sternum below its inner edge, in the
upper space between the lamina of the mediastinum.

THE TRACHEA. 517

CHAPTER XVII.

OF THE TRACHEA AND THE LUNGS.

ALTHOUGH the principal part of the windpipe is situated in
the neck above the cavity of the thorax, it is so intimately
connected with the lungs, that it is necessary to describe them
together.

Of the Trachea.

Trachea is the technical name for the windpipe, or the tube
which passes from the larynx to the lungs.

This tube begins at the lower edge of the cricoid cartilage,
and passes down the neck in front of the oesophagus as low as
the third dorsal vertebrae, when it divides into two branches
called Bronchia, one of which goes to the right and the other
to the left lung, in which they ramify very minutely.

— The right bronchium is larger than the left, in proportion
to the greater size of the right lung. It is also shorter and is
placed more in front, and is more horizontal than the left, in
consequence of the right lung being shorter in its vertical
diameter, and longer in its antero-posterior than the lung of
the left side. It enters near the centre of the root of the lung,
opposite to the fourth dorsal vertebra.

— The left bronchium enters the root of the left lung, opposite
the fifth dorsal vertebrae. The right bronchium is embraced
at its upper part by the vena azygos, the left by the arch of
the aorta. —

There is in the structure of the trachea, a number of flat cartil-
aginous rings placed at small distances from each other, the edges of
which are connected by membrane, so that they compose a tube.

These cartilaginous rings are not complete, for they do not
form more than three-fourths or four-fifths of a circle ; but their
ends are connected by a membrane which forms the posterior
part of the tube.

44

518 STRUCTURE OF THE TRACHEA AND BRONCHIA,

They are not alike in their size or form ; some of them are
rendered broader than others, by the union of two or three
rings with each other, as the uppermost. The lowermost also b
broad, and has a form which is accommodated to the bifurca-
tion of the tube where it forms the bronchia. Their number
varies in different persons, from fifteen to twenty.

These rings may be considered as forming a part of the first
proper coat of the trachea, which is composed of them, and of
an elastic membrane that occupies all the interstice between
them ; so that the cartilages may be regarded as fixed in this
membrane.

A similar arrangement of rings exists in the great branches
of the bronchia ; but after they ramify in the lungs, the carti-
lages are no longer in the form of rings : they are irregular in
their figures, and are so arranged in the membrane, that they
keep the tube completely open. These portions of cartilage do
not continue throughout the whole extent of the ramifications ;
for they become smaller, and finally disappear, while the mem-
branous tube continues without them, ramifying minutely, and
probably forming the air-cells of the lungs.
— At the orifices of the bronchial ramifications, the existence
of a semilunar cartilage has been pointed out by Prof. Horner,
forming rather more than half of their circumference, and
having its concave edge turned upwards. These cartilages
appear to be intended to keep the orifices open.* —

The small bronchial tubes after they become entirely membra-
nous are very elastic : the lungs are very elastic also ; and it is pro-
bable that their elasticity is derived from the membranous bronchiae.

On the inside of this coat of the trachea is an arrangement
of muscular fibres, which may be called a muscular coat. It is
best seen by pealing off or removing the internal coat, to be
next described.

On the membranous part of the trachea, where the cartilagi-
rous rings are deficient, these muscular fibres run evidently in
r. transverse direction : in the spaces between the cartilages

* Special Anatomy, by W. E. Horner, M. D. Prof. Anat. Univers. Penn-
sylvania.

STRUCTURE OF THE TRACHEA. AND BRONCHIA. 519

their direction is longitudinal. There is some reason to doubt
whether these longitudinal fibres are confined altogether to
the spaces between the cartilaginous rings, and attache^ only
to their edges, because there is a fleshy substance on the inter-
nal surface of the rings, which appears to be continued from
the spaces between them.

The internal coat of the trachea is a thin and delicate mem-
Fig. 129.* brane, perforated with an im-

mense number of small foramina,
which are the orifices of mucous
ducts.

On the surface of this mem-
brane there is an appearance of
longitudinal fibres which are not
distributed uniformly over it, but
,c run in fasciculi in some places,
and appear to be deficient in
others. These fasciculi are par-
ticularly conspicuous in the rami-
fications of the bronchia in the
lungs.

— TMany of the German anato-
mists have described these as
longitudinal muscular fibres, the
object of which is to shorten to some extent the air-passages
during their contraction, and to assist in loosening the mucus
and other matters which accumulate in their cavities. I have
examined them carefully in the ox and elephant, where
they are strongly marked ; they appeared to me to consist
only of longitudinal folds of mucous membrane, with a basis
of the fibrous contractile tissue. The same arrangement of
the circular fibres, and these peculiar longitudinal fibres, can
be traced with the microscope down the bronchia as far as

* Fig. 129, represents the larynx, trachea, and bronchia ; on one side is seen
the right lung ; on the left, the lung has been destroyed to show the ramification
of the bronchia, a, Larynx, b, Trachea, dividing into right and left bron-
chium ; the left is the smaller, longer, and inclined most downwards, c, Larger
divisions of the left bronchium ; e, the more minute, d, Right lung. — F.

520 THE LUNGS.

these can be distinctly opened. The contractibility of the pul-
monary tissue under the influence of galvanism observed by
Dr. C. J. B. Williams, seems to establish the muscularity of the
circular fibres. —

On the posterior membranous portion of the trachea, where
the cartilages are deficient, a considerable number of small
glandular bodies are placed, which are supposed to communicate
with the mucous ducts that open on the internal surface. If
these bodies are removed from the external surface of this
portion, and the muscular fibres are also removed from the
internal, a very thin membrane only remains, which is very
different from that which is left between the rings, when the
fleshy substance is removed from that situation.

The reason of the deficiency in the rings, at this posterior
part, is not very obvious.* It continues in the bronchia until
the form of their cartilages is changed in the lungs : if it were
only to accommodate the oesophagus, during the passage of
food, there would be no occasion for its extension to the
bronchia.

At the bifurcation of the trachea, and on the bronchia, are a
number of black colored bodies, which resemble the lymphatic
glands in form and texture. They continue on the ramifications
of the bronchia some distance into the substance of the lungs.
Their number is often very considerable ; and they vary in size
from three or four lines in diameter to eighteen or twenty. As
lymphatic vessels have been traced to and from them during
their course to the thoracic duct, they are considered as lym-
phatic glands.

Of the Lungs.

There are two of these organs : each of which occupies one
of the great cavities of the thorax.

When placed together, in their natural position, they resem-
ble the hoof of the ox, with its back part forward ; but they are

* Dr. Physick has advanced the opinion that it enables a person to expel the
mucus of the lungs by contracting the size of the trachea, and consequently
increasing the velocity or impetus of the air. — H.

ROOT OF THE LUNGS. 521

at such a distance from each other, and of such a figure, that
they allow the mediastinum and heart to intervene ; and they
cover every part of the heart anteriorly, except a small portion
at the apex.

Each lung fills completely the cavity in which it is placed,
and every part of its external surface is in contact with some
part of the internal surface of the cavity ; but when in a natural
and healthy state, it is not connected with any part except the
lamina of the mediastinum.

— The lower extremity or base of each lung, rests upon the
pleural lining of the diaphragm, and fills up the angle between
the diaphragm and the ribs ; the superior end projects upwards and
backwards along the first rib and above the level of the clavi-
cle, so as to be separated from the scalenus anticus muscle only
by the pleura. In laborious respiration, the elevation of the
apex of the lung is increased, and the motion it produces
becomes visible at the root of the neck. The external face of
each lung is convex, to suit the contour of the thoracic parietes.
The internal surface, and especially that of the left, is concave to
accommodate the heart and pericardium. The anterior edge
is thin and sinuous, and presents on the left side a deep notch
fitted to the shape of the heart, and a sort of lobular projection
which in part covers that organ during deep inspiration. —

One great branch of the trachea and of the pulmonary
artery passes from the mediastinum to each lung, and enters
it at a place which is rather nearer to the upper rib than to the
diaphragm, and much nearer to the spine than the sternum :
at this place also the pulmonary veins return from the lungs to
the heart.

These vessels are enclosed in a membrane, which is continued
over them from the mediastinum, and extended from then to the
lung. Thus covered they constitute what has been called the
Root of the Lung.

When their covering, derived from the mediastinum, is
removed, the situation of these vessels appears to be such
that the bronchia are posterior, the branches of the pulmonary
44*

522 COLOR OF THE LUNGS.

artery are rather above and before, and the veins below and
before them.

Each of these vessels ramifies before it enters into the
substance of the lungs : the bronchia and the branches of the
pulmonary artery send each a large branch downwards to the
inferior part of the lungs, from which the lower pulmonary
veins pass in a direction nearly horizontal. In general, each
of the smaller ramifications of the bronchia in the lungs is
attended by an artery and a vein.

Each lung is divided, by very deep fissures, into portions
which are called Lobes. The right lung is -composed of three
of these lobes, and the left lung of two. (See fig. 128, page
515.)

— Each of these lobes are subdivided into many smaller parts
called lobules, which are marked out on the surface of the lungs,
by various angular lines. The left bronchium divides into two
principal branches for the lobes of the left lung, and the right
into three for the lung of that side ; after which, a still further
subdivision takes place, so that a terminal bronchial branch is
sent to each lobule. —

The lungs are covered, as has been already stated, with the
reflected portion of the pleura continued from the mediastinum,
which is very delicate and almost transparent. They have,
therefore, a very smooth surface, which is kept moist by exuda-
tion from the arteries of the membrane.

a* The Color of the Lungs is different in different subjects.
In children they are of a light red color ; in adults they are
often of a light gray, owing to the deposition of a black pig-
ment in the substance immediately under the membranes
which form their external surface. Their color is often
formed by a mixture of red and black. In this case they are
more loaded with blood, and the vessels of the internal mem-
branes being distended with it, the red color is derived from
them.

The black pigment sometimes appears in round spots of three
or four lines in diameter : under the external membrane it is
often in much smaller portions, and sometimes is arranged in

STRUCTURE OF THE LUNGS. 523

lines in the interstices of the lobuli, to be hereafter mentioned.
It is also diffused in small quantities throughout the substance
of the lungs.

The sources of this substance, and the use of it, are unknown.

The lungs are of a soft spongy texture ; and, in animals that
have breathed, they have always a considerable quantity of
air in them.

They consist of cells, which communicate with the branches
of the trachea that ramify through them in every part. These
cells are extremely small, and the membranes which compose
them are so thin and delicate, that if they are all filled by an
injection of wax, thrown into the trachea, the whole cellular
part of the lung will appear like a mass of wax. If a corroded
preparation be made of a lung injected in this manner with
force, the wax will appear like a concretion.

These effects of injections prove that the membranes of
which the cells are formed are very thin ; and, of course, that
their volume is very small when compared with the capacity
of the cells.

In those corroded preparations, in which the ramifications of
the bronchia are detached from the wax of the cells, these
ramifications become extremely small indeed. — The cells above
alluded to are in fact but the ultimate termination of the last
branches of the bronchia in small dilated sacs, called the bron-
chial or pulmonary cells. —

If the lungs of the human subject, or of animals of similar
construction, be examined when they are inflated, their cellu-
lar structure will be very obvious, although their cells are so
small that they cannot commonly be distinguished by the naked
eye. Each of the extreme ramifications of the bronchia
appears to be surrounded by a portion of this cellular sub-
stance, which is gradually distended when air is blown into
the ramification.

This cellular substance is formed into small portions of
various angular figures, which are denominated Lobuli : these
can be separated to a considerable extent from each other.

524 STRUCTURE OF THE LUNGS.

They are covered by the proper coat of the lungs, which is
extremely delicate, and closely connected to the general cover-
ing derived from the pleurae. Between the lobuli, where they
are in contact with each other, there is a portion of common
cellular substance, which is easily distinguished through the
membrane covering the lungs. This is very distinct from the
cellular structure which coramunicates with the ramifications
of the bronchia, and contains air ; for it has no communica-
tion with the air, unless the proper coat of the lungs be rup-
tured. If a pipe be introduced by a puncture of the external
coat of the lungs, and this interstitial cellular membrane be
inflated, it will compress the lobuli. This cellular membrane
is always free from adipose matter : it may be easily examined
in the lungs of the bullock.

Upon the membranes which compose the air-cells, the pul-
monary artery and vein ramify most minutely ; and it seems
to have been proved by the united labors of chemists and
physiologists, that the great object of respiration is to effect a
chemical process between the atmospheric air, when taken into
the air-cells, and the blood which circulates in these vessels.

In addition to the blood-vessels which thus pass through the
substance of the lungs, there are several smaller arteries deno-
minated Bronchial, which arise either from the upper inter-
costal, or from the aorta itself; they pass upon the bronchia,
and are distributed to the substance of the lungs. The veins
which correspond with these arteries terminate ultimately in
the vena azygos.

The nerves of the lungs are small in proportion to the bulk
^ of these organs. They are derived principally from the par
vagurn and the great sympathetic nerves.

— They form one plexus on the front, and another on the
posterior surface of the bronchia, along which they are con-
ducted to the minutest subdivision of the latter in the substance
of the lungs. —

The elasticity of the air-cells of the lungs and of the ramifi-
cations of the bronchia which lead to them, is apparent in their

STRUCTURE OF THE LUNGS. 525

rapid contraction after distention, and by the force with which
they expel the air which is used to inflate them when taken out
of the thorax.

— The specific gravity of the lungs is not naturally less than
that of many other tissues. In a still-born child, sections of it
sink in water like a piece of muscle. But when its cells have
been once distended by air in respiration it becomes impossible
to extrude the air completely (unless the lung is subjected to
strong compression) and the lung floats upon the water and
appears to have the least specific gravity of all the animal tissues.
The lungs are endowed with a considerable degree of elasticity ;
this as before observed appears to be derived from the elastic
tissue of the bronchia which is spread universally through the
lungs. When distended the lungs have a constant tendency
either in or out of the body to return upon themselves and
expel the air.

— It will now be seen that the proper tissue of the lungs, the
parenchyma, or areolar tissue, is very complicated. It consists
of the cells of the bronchia for the reception of air, which are
formed internally of mucous membrane, and externally most
probably of a thin expansion of the yellow elastic ligamentous
layer of the bronchia ; of branches of the pulmonary arteries
and veins, which run over the outer surface of the cells, the for-
mer bringing the black blood, and the latterconveying it away
after it has been changed by the action of the air through the
walls of the cells ; of the bronchial arteries and veins for the
purpose of nutrition ; of absorbent vessels to remove the mole-
cules as they become effete ; of filaments of the sympathetic and
par vagtim nerves, which preside over the function of hematosis,
and put the lungs in connexion with the brain ; and lastly of
cellular tissue which unites the whole together. The mucous
membrane lining the trachea, bronchia, and air cells, when ex-
amined with the microscope, have been found lined with a colum-
nar epithelium, mounted with vibratile cilia of the same kind as
has been described covering the Schneiderian membrane. The
use of the cilia in these organs, it is believed, is that of aiding in
urging the secretions upwards towards the larynx.

526 THORAX OF THE FCETUS.

— Between the bronchial and pulmonary arteries and veins,
there is an intimate anastomosis so that either system of ves-
sels may be filled by forcing a fine injecting fluid through the
other. The cells of each lobule, according to Professor Homer,
Cloquet, and some other anatomists of distinction, communi-
cate laterally with each other. Reisseissen, Gerber, and other
microscopists, figure each on§ as a perfect cul de sac ; the
development of the lungs in the foetus resembling in its early
stages very closely that of the compound glands. The diame-
ter of these cells has been measured by Weber of Leipzig,*
by the aid of a micrometer attached with extreme care and
ingenuity to a microscope. According to him they are upon an
average about ^ part of an inch in diameter, which makes them
five or* six times larger than the cells of the parotid gland, and
fifteen or twenty times larger than the finest capillary blood-
vessels measured on a portion of skin which had been very
perfectly injected by Dr. Pockels of Brunswick. —

The Thorax of the Fcetus.

In the cavity between the lamina of the mediastinum, where
they approach each other from the first ribs, is situated, a sub-
stance which is denominated the

Thymus Gland.

This substance gradually diminishes after birth, so that
in the adult it is often not to be found ; and when it exists it is
changed in its texture, being much firmer, as well as greatly
diminished.

In the foetus it is of a pale red color; and during infancy
it has a yellowish tinge. It generally extends from the thyroid
gland, or a little below it, to the pericardium. From its supe-
rior portion two lateral processes are extended upwards : below,
it is formed into two lobes, which lie on the pericardium.

If an incision be made into its substance, a fluid can be

* Meckel's Archiv. fur Anat. and Physiol., 1830.—

THORACIC FASCIA. 527

pressed out, which has a whitish color, and coagulates upon the
addition of alcohol.

Although it is called a gland, no excretory duct has ever been
found connected with it.

— The thymus gland in the foetus at birth, extends from the
fourth rib, as high up as the thyroid gland. It rests upon the
pericardium below, and is separated from the arch of the aorta
and the great vessels, by a fascia, called by Sir A. Cooper; the
thoracic, which is composed of a dense layer of fibre-cellular
membrane, stretched between the concave margins of the first
rib of each side so as to pass horizontally across the upper open-

Fig. 130 *

ing of the thorax. It is connected below with the fibrous sac of
the pericardium, with the arch of the aorta which it in a measure
sustains and the great vessels that come off from it. Above,
it is connected with the sheath of the carotid, and the deep
cervical and tracheal fasciae. This fascia has an opening in

* A section of the thymus gland at the eighth month, showing its anatomy.
This figure is taken from one of Sir Astley Cooper's beautiful engravings. 1.
The cervical portions of the gland. The independence of the two lateral glands
is well marked. 2. Secretory cells seen upon the cut surface of the section ;
these are observed in all parts of the section. 3, 3. The pores or openings of
the secrelory cells and pouches ; they are seen covering the whole internal
surface of the great central cavity or reservoir. The continuity of the reservoir
in the lower or thoracic portion of the gland, with the cervical portion, is seen,
in the figure.

528 INTIMATE STRUCTURE OF THE THYMUS GLAND.

front, through which passes up the cervical portion of the
tbymus gland.

— The gland consists of two halves, connected in the middle
by cellular tissue only, which may properly be called a right
and left lobe. According to Sir A. Cooper, who has published
a beautiful monograph on the structure of this organ, the
gland grows gradually with the increasing growth of the foetus,
till the seventh month. During the ninth it is suddenly and
greatly increased in size, and at birth weighs two hundred
and forty grains. It continues to enlarge till the end of the
first year after birth, when it begins to diminish in size, and
by the period of puberty has almost entirely disappeared.
Each right and left lobe, is composed of lobules disposed in a
spiral form round a central cavity, which is called a reservoir.

The lobules are held together by dense cellular tissue, and,

the whole gland is surrounded by a coarse cellular capsule.
The lobules which make this a conglomerate gland are very
numerous, and vary in size from that of the head of a pin to a
common pea. In each lobule there is a small cavity or secre-
tory cell. Several of these cells open into a small pouch, and
this again into the central cavity or reservoir, which is lined by
a vascular mucous membrane.

— Each lobe of the gland may be carefully unraveled by
removing the coarse cellular capsule and vessels, and dissecting
away the firm cellular tissue that holds the lobules together ;
the reservoir then, which in its natural state is folded in a
serpentine manner upon itself, may be drawn out into a length-
ened tubular cord, around which the lobules are clustered in
a spiral manner, and resemble knots upon a cord, or a string
of beads. The reservoir, pouches, and cells, contain a white
fluid like chyle or cream, with a small admixture of red
globules. The use of this gland is not known. Sir A. Cooper,
is disposed to believe, in common with several of the older writers,
that the gland is designed to prepare a fluid from the blood of
the mother, well fitted for the growth and nourishment of the
foetus before its birth, and consequently, before chyle is formed
by it from food ; this process continuing for a short time after

THORAX OF THE FOETUS.

529

Fig.

birth — the quantity of fluid secreted from the thymus, gradu-
lly declining, as that of chylification becomes perfectly estab-
shed.— j

The arteries of this body are de-
rived from the thyroid branches of
the subclavians, from the internal
mammaries, and the vessels of the
pericardium and mediastinum. — The
veins terminate mainly in the left
vena innominata.

— The nerves are very minute, and
are chiefly from the plexus about the
internal mammary artery which comes
from the superior thoracic ganglion of
the sympathetic. The lymphatics ter-
minate at the common junction of the
other vessels of the kind, at the union
of the internal jugular and subclavian
veins. Sir A. Cooper has injected
them but once in the human foetus.
In the calf he found two large lym-
phatic ducts, see fig. 131, which com-
mence at the upper extremities of the
lobes, and pass downwards to termi-
nate at the junction of the jugular and
subclavian of each side. These ves-
sels he considers the absorbent ducts

of the glands — the thymic ducts which carry the fluid from

the reservoir of the thymus into the veins. —

The Heart,

And the great arteries which proceed from it, have some very
interesting peculiarities in the foetus.

* The course and termination of the " absorbent ducts " of the thymus of
the calf; from one of Sir Astley Cooper's preparations. 1. The two internal
jugular veins. 2. The superior vena cava. 3. The thoracic duct, dividing into
two branches, which re-unite previously to their termination in the root of the
left jugular vein. 4. The two thymic ducts ; that on the left side opens into
the thoracic duct, and that on the right into the root of the right jugular vein.

45

530 THE THORAX OF THE FffiTUS.

In the septum between the two auricles, is a foramen of suf-
ficient size to permit the passage of a large quill, which inclines
to the oval form, with its longest diameter vertical when the
body is erect. On the left side of the septum, a valve, formed
by the lining membranes, is connected to this foramen ; and
allows a free passage to a fluid moving from the right auricle
to the left ; but prevents the passage of a fluid from the left to
"the right. This structure is evidently calculated to allow some
of the blood which flows into the right auricle from the two
venae cavae to pass into the left auricle of the heart, instead of
going into the right ventricle. As the contents of the left
auricle pass into the left ventricle, and from thence into the
aorta, it is obvious that the blood which passes from the right
auricle into the* left through this foramen, must be transmitted
from the system of the vena cava to the system of the aorta,
without going through the lungs, as it must necessarily do in
subjects who do not enjoy the foetal structure.

— The valve, with which in the foetus the foramen ovale
is provided on the side of the left auricle, is of a semilunar
shape and called the valve of Botal ; it has a convex border,
adherent, and turned downwards ; and a concave border, free,
and turned upwards. The angles resulting from the union
of these borders are at birth attached to each side of the fora-
men about a quarter of an inch distant from each other. The
valve makes its appearance in the foetus at the third month of
intra-uterine existence, and gradually increases in size, so as
to more than cover the foramen at the period of birth. When
the child breaths and the lungs become filled with blood, the
fluid, entering the left auricle by the pulmonary veins, throws
down the valve against the septum auriculorum, to which its
free border usually becomes firmly united.

— Occasionally, however, the union of the parts is found so
incomplete, even in old persons, as to allow a probe or even
the handle of a scalpel to be passed obliquely through the
opening : the obliquity of the orifice being such, as usually to
enable it to act as a perfect valve. A communication of this
sort, of greater or less magnitude between the auricles, exists

THE THORAX OF THE FffiTUS. 531

in adults, according to Biot, in the ratio of one to four. But
judging from my own observations, the proportion of cases in
which the opening exists is by no means so great. Someftimes
the foramen is met with in adults so dilated as to be nearly an
inch in diameter. I have met with two cases of this sort in the
dissecting-room, both of which occurred in females between
twenty and thirty years of age. The nutritive functions
appeared to have been perfectly well performed in both these
subjects, judging from the state of the body ; the right auricle
and ventricle were dilated and hypertrophied so as to present
the same thickness of parietes as the corresponding parts of the
left side. The tricuspid valves, and the semilunar valves of the
pulmonary artery were thickened, and presented cartilaginous
concretions on their edges, in which the work of ossification had
just commenced. This thickening and ossification of the valves
in the normal formation of the heart is almost wholly peculiar
to the valves of the left side, and appears to be caused, as was
first suggested by Cruveilhier, by the force with which the blood
is dashed against the valves, in the forcible contractions of the
ventricle. —

The, Pulmonary Artery and the Aorta,

Have a communication in the foetus, which is very analogous
to the communication between the auricles of the heart.

From the pulmonary artery, where it divides into the two
great branches, another large branch continues in the direction
of the main trunk, until it joins the aorta ; with which vessel it
communicates at a small distance below the origin of the left sub-
clavian artery. In the young subject that has never respired,
it appears as if the pulmonary artery was continued into the
aorta, and sent off in its course a branch on each side, much
smaller than itself, to each lung. In subjects that have lived
a few days, these branches to the lungs are much larger ; and
then the main pulmonary artery appears to have divided into
three branches : one to each lung, and one to the aorta ; but
that which continues to the aorta is larger than either of the others.

532 GENERAL OBSERVATIONS.

In the course of time, however, this branch of the aorta is
contracted, so that no fluid passes through it ; and it has
the appearance of a ligament, in which state it remains.

The course of the blood from the right ventricle, through the
pulmonary artery to the aorta below its curve, is more direct
than that from the left ventricle to the same spot through the
aorta at its commencement. The column of blood in the aorta
below its curve is evidently propelled by the force of both
ventricles : and this circumstance, although it seems to pro-
ceed merely from the state of the foetal lungs, is particularly
calculated for the very extensive circulation which the foetus
carries on, by means of the umbilical arteries and vein in the
placenta.

The Lungs of the Fwtus

Differ greatly from those of the adult. They appear solid,
as if they were composed of the parenchymatous substance
which constitutes the matter of glands, rather than the light spongy
substance of the lungs of adults. They differ also in color from
the lungs of older subjects, being of a dull red.

They have greater specific gravity than water ; but if air be
once inspired, so much of it remains in them that they ever
afterwards float in the former fluid.

The nature of the process of respiration, and its effects upon the animal
economy, particularly upon the action of the heart, appear to be much better
understood at this time than they were before the discovery of the composition
of the atmosphere, by Dr. Priestley and Mr. Scheele. The publications upon
this subject, which have appeared since that period, namely, 1774, are there-
fore much more interesting to the student of medicine than those which
preceded them. Two of these publications ought to be particularly noticed
by him ; namely, an essay, by Dr. Edward Goodwyn, entitled, " The Con-
nexion of Life with Respiration ; " — and the " Physiological Researches of
M. Bichat upon Life and Death." Part Second.*

The general doctrines respecting the oxygenation or decarbonization of the blood
and the absolute necessity that it should take place to a certain degree in

* The student will derive much information respecting the publications on this subject,
prior to 1804, from Dr. Bostock's Essay on Respiration.— Since the publication of that essay
several interesting papers on respiration have appeared, namely, Two Memoirs by the late
Abbe Spallanzani ; " An Inquiry into the Changes induced on Atmospheric Air by the Ger-
mination of seeds," &c., by Ellis ; two very important communications by Messrs. Allen and
Pepys in the Transactions of the Royal Society of London for 1808 and 1809 ; and " Farther
Inquiries into the Changes induced on Atmospheric Air," also by Ellis.

CASES OF MALFORMATION. 533

order to preserve life, are confirmed by a number of cases of malformation
of the heart or the great vessels, in which the structure was such that a con-
siderable portion of venous blood passed from the right side of the heart to
the aorta, without going through the lungs. In these different cas^s, not-
withstanding the structure was somewhat varied, the symptoms produced
were very much alike j differing in the respective patients in degree only,
and not in kind.

The symptoms indicating this structure, are blue color of the face, (such as
generally accompanies suffocation,) extending more or less over the whole
body, and particularly apparent under the nails of the fingers and toes ;
anxiety about the region of the heart ; palpitation ; laborious respiration ;
sensations of great debility, (fee. : all of which are greatly aggravated by
muscular exertion. These effects have generally appeared to be proportioned
to the quantity of venous blood admitted into the aortic system.*

When these appearances take place immediately after birth, it is probable that
they depend entirely upon malformation of the heart or great vessels ; but
when they commence at a subsequent period, they are commonly the effect of
a diseased alteration in the lungs. They sometimes occur near the termina-
tion of fatal cases of pneumonia or catarrh ; but a different cause, which has
not latterly been suspected, appears to have produced them in the following
case, related by Dr. Marcet, in the first volume of the Edinburgh Medical
and Physical Journal.

The blue color occurred in a young woman, twenty-one years of age, in whom
it had never been observed before. It came on during an affection of the
breast, and was attended with great prostration of strength and difficulty of
breathing, as well as cough, oedema of the hands and feet, and several other
symptoms. About seven weeks after the commencement of these symptoms,
she died ; when it was ascertained by dissection, that there was no unnatural
communication whatever between the cavities of the heart, and that its valves were
all in a perfect and natural state. The lungs were free from tubercles, or any
other appearance of disease. Their substance seemed more compact than
usual, especially the left lung, although it did not sink in water; but they
adhered every where to the inner surface of the thorax, to the diaphragm and to
the pleura covering the pericardium. This case is the more remarkable, be-
cause numberless instances have occurred, in which very large portions of
the external surface of the lungs have been found, upon dissection, to adhere
to the internal surface of the thorax, without the occurrence of such symp-
toms during life.

It may be inferred, from a statement published by M. Dupuytren, in a volume
of the Proceedings of the National Institute of France, that the oxygenation
or decarbonation of the blood is much affected, in respiration, by an influence
exercised by the nerves which are appropriated to the lungs. From his
account it appears, that although the complete division of the eighth pair of
nerves produces death after some time ; yet in the horse, whose nerves are

* Cases of this kind are related in several of the periodical publications on medical sub-
jects. Two of them were described by Dr. William Hunter in the sixth volume of " Medical
Observations and Inquiries by a society of Physicians in London ; " one quoted by Dr.
Goodwyn, is in the Observationes Anatomicae of Sandifort ; and another by Dr. J. 8.
Dorsey, has been published in the first number of the New England Journal of Medicine and
Surgery.

45*

534 EFFECT OF VENOUS BLOOD ON THE HEART.

thus divided, life continues, and respiration goes on, from half an hour to
ten hours ; but his arterial blood is in a state of great disoxygenation or
carbonation during this time. This fact is more remarkable because venous
blood, contained in a bladder exposed to the open air will become oxygenated
or decarbonated.

It is also asserted in another Memoir, read to the National Institute by Dr. J. M.
Provencal ; that animals, in whom the eighth pair of nerves has been divided,
do not consume so much oxygen, or produce so much carbonic acid, by a
considerable degree, as they did before the division of these nerves ; and that
their temperature is considerably reduced.*

The effect, that venous blood occasions death, when it is admitted into the left
ventricle of the heart, and the aorta, is truly important. Dr. Goodwin
explained it by suggesting that this blood was not sufficiently stimulating to
produce the necessary excitement of the heart ; but on this occasion one of his
friends proposed to him the following question : Why does venous blood affect
the left side of the heart in this injurious manner, when it appears to exert no
noxious effects whatever on the right side of that organ ? His reply may be
seen in a note at the 82d page of his Essay, in the first edition. Bichat has
offered a solution which completely resolves this difficulty, viz. " The effect of
venous blood upon the heart is produced by the presence of this blood in the
proper, or coronary arteries of that organ, and not in its great cavities." For
the animation of the heart, like that of the other parts of the body, depends
upon the state of the blood in the arteries which penetrate its texture.f And
•while the heart acts, the blood of the coronary arteries will be the same with
that of the left ventricle. See Bichat's Researches, P. II. art. 6, $ 2.

The French anatomists at one time entertained some peculiar opinions respecting
the course of the blood in the fostus, which have a particular relation to the
subject last mentioned. Winslow, who paid great attention to the valve of
Eustachius in the right auricle of the heart, was of opinion, that this valve
was calculated for some important purpose in the foetal economy.! Although
his hypothesis respecting its particular use has not been retained by his
countrymen, many of them have adopted his general sentiment ; and among
others Sabatier. That learned anatomist believed that this valve, in the
foetal state, serves to direct the blood of the inferior cava, after its arrival in the
right auricle through the foramen ovale into the left auricle ; while the blood of
the upper cava passes directly into the right ventricle. His opinion seems to be
supported to a certain degree —

1. By the direction in which the two columns of blood enter the auricles
from the two venae cavae.

2. By the position of the Eustachian valve.

3. By the foraman ovale, when its valve is complete ; as the passage
through it from the right to the left, is at that time oblique, and from below
upwards.

* These Memoirs were republished in the Electic Repertory of Philadelphia for April and
October, 1811.

t It is probable that the contents of the great cavities of the heart have no more effect
upon its animation than the contents of the stomach and bowels have upon the animation
of those organs.

J See Memoirs of the Academy of Sciences for 1717 and 1725,

SENTIMENTS OF SABATIER, ETC. 535

The theory of Sabatier appears to be this :— the umbilical vein brings from the
placenta blood which has a quality essential to the animation of the foetus.
If there were no particular provision to the contrary, a large portion of this
blood, after passing from the umbilical vein by the inferior cava into^rhe right
auricle of the heart, would proceed by the right ventricle through the pulmo-
nary artery and arterial canal, into the aorta, below the origins of the carotid
and subclavian arteries ; and consequently none of it would pass to the head
and upper extremities, but a considerable part would return again by the
umbilical arteries to the placenta, without circulating through the body : while,
on the other hand, the blood which passed by .the carotid and subclavian
arteries to the head and upper extremities returning from them to the heart
by the superior cava, might pass from the right auricle to the left auricle and
ventricle and the aorta, and so to the head and upper extremities again,
without passing through the placenta. But by means of this valve, the blood
of the lower cava, and of course of the umbilical vein, is directed to the left
auricle and ventricle and the aorta, by which a considerable portion of it will
necessarily pass to the head and upper extremities ; while the blood which
returns from these parts by the superior cava, must consequently pass from
the right auricle into the right ventricle and pulmonary artery; from whence
a large portion of it will proceed through the arterial canal into the aorta
beyond the carotids and subclavians, and of this portion a considerable part
will go to the placenta by the umbilical arteries. Sabatier 'compares the
course of the blood in the foetus to the course of a fluid in a tube which has
the form of the numeral character 8.* If this doctrine be true, the progress
of the blood in the fostus and placenta is very analagous to that of the double
circulation of the adult ; the character 8 answering equally well in the
description of either subject.

According to Sabatier, the blood of the placenta takes this peculiar course
through the heart, in order that some of it may be carried to the head and
upper extremities. But an additional reason may be suggested, which appears
to be of great importance ; namely, the supplying of the coronary or proper
vessels of the heart, with some of the same blood.

The heart of the adult, as has been before stated, cannot act without its proper
or coronary arteries are supplied with arterial blood. The heart of the foetus
performs a more extensive circulation than that of the adult, and, therefore,
is probably in greater need of such blood. But unless the blood of the placenta
pass through the foramen ovale into the left auricle and ventricle, and so to the
aorta, it cannot enter the coronary arteries which originate at the commencement of
the aorta ; for the blood which flows from the right side of the heart through
the arterial canal, passes into the aorta at so great a distance from the orifices
of the coronary arteries, that it certainly cannot enter them.

The whole of this doctrine seems to be supported by a fact very familiar to
accoucheurs, viz. the occurrence of death in the foetus whenever the circula-
tion through the umbilical cord is suspended during fifteen or twenty min-
utes ; for as the placenta imparts to the foetal blood a quality essential to
life, some arrangement seems necessary to provide for the equal distribution

* See Sabatier's Paper on this subject, in the Memoirs of the Academy of Sciences, for
1774.

536 ^ USUAL CASES OF MALFORMATION.

of the blood which comes from this organ, and especially for carrying the
requisite proportion of it to the substance of the heart.

Life has existed for some time with a structure very different indeed from that
which is natural. In the series of elegant engravings relating to morbid
anatomy, published by Dr. Baillie, is the representation of a heart, in which
the venae cavae opened into the right auricle, and the pulmonary veins into
the left auricle, in the usual manner ; but the aorta arose entirely from the
right ventricle, and the pulmonary artery as completely from the left. The
canalis arteriosus, however, passed from the pulmonary artery to the aorta,
and the foramen ovale existed. In this case, it is evident, that the pulmonary
artery must have carried back to the lungs the arterial blood which came
from them by the pulmonary veins, with a small quantity of venous blood
that passed into the left auricle through the foramen ovale; and that the aorta
must have returned to the body the venous blood, which just before had been
brought from it by the venae cavae, with a small addition of arterial blood
that passed through the ductus arteriosus. Yet with this structure the child
lived two months after its birth.

A case, which had a strong resemblance to the foregoing, occurred in Philadel-
phia, and was examined by the author of this work. The venae cavae termi-
nated regularly in the right auricle, and the pulmonary veins in the same
regular manner in the left ; but the pulmonary artery arose from the left
ventricle, and the aorta from the right. There was no communication between
these vessels by a canalis arteriosus ; but a large opening existed in the septum
between the auricles.

It is very evident, that, in this case also the pulmonary artery must have
returned to the lungs the arterial blood as it came from them, and the aorta
must have carried back to the general system the venous blood brought to
the heart by the cavae j excepting only those portions of the arterial and
venous blood which must have flowed reciprocally from one auricle into the
other, and thus changed their respective situations.

The subject was about two years and a half old. The heart was nearly double
the natural size, and the foramen, or opening in the septum between the
auricles, was eight or nine lines in diameter. The pulmonary artery was
larger in proportion than the aorta or the heart.

With this organization, the child lived to the age above specified. His
countenance was generally rather livid ; and this color was always much
increased by the least irregularity of respiration. His nails were always
livid. He sometimes appeared placid, but more frequently in distress. He
never walked, and seldom, if ever, stood on his feet. When sitting on the
floor, he would sometimes push himself about the room; but this muscular
exertion always greatly affected his respiration. He attained the size
common to children of his age, and had generally a great appetite. For
some weeks before death his legs and feet were swelled.

It is probable that the protraction of life depended upon the mixture of the
blood in the two auricles ; and that they really were to be considered as one
cavity, in this case.

There seems reason to believe, that in adults of the common structure, there is
no passage of blood from one auricle to the other, when the foramen ovale

FORAMEN OVALE. 537

has remained open ; because in several persons in whom it was found by
dissection to have remained open, there were no appearances during life,
that indicated the presence of disoxygenaied blood in the aortic system. It
is probable, that the small size of the foramen ovale, the valvular structure
which generally exists there, and the complete occupation of the left auricle
by the blood flowing from the pulmonary veins, prevent the passage of blood
from the right auricle to the left, in such persons ; whereas in the case in
question, the opening between the auricles was very large indeed, and there
was no appearance of a valve about it.

Although it be admitted, that in adults with the foramen ovale pervious, there
is no transmission of blood from the right to the left auricle ; there is every
reason to believe, that this transmission goes on steadily in the foetus. To
the arguments derived from the structure and the nature of the case, it may
be added, that the pulmonary veins, in the foetal state, carry to the left auri-
cle a quantity of blood, not sufficient to fill it ; while the vense cavae carry to
the right auricle, not only the whole blood of the body, but of the umbilical
cord and placenta : some of which must flow into the unfilled left auricle,
when the right auricle becomes fully distended.

The question, how far the functions of the heart and lungs are dependent upon
the brain, is very important, and has often been agitated with great zeal. In
favor of the opinion that the motions of the heart are independent of the
brain, may be stated the numerous cases in which the brain has been deficient
in children, who have notwithstanding lived the full period of utero-gesta-
tion, and even a short time after birth, and have arrived at their full size,
with every appearance of perfect vigor and action in the heart. In support
of the doctrine, that the action of the heart is immediately dependent upon
the brain, it may be observed, that no organ of the body appears to be so
much influenced by passions and other mental affections as the heart. These
contradictory facts have occasioned this question to be considered as unde-
cided, if not incapable of solution ; although Cruikshank and Bichat* have
stated circumstances very favorable to the opinion that the motions of the
heart are independent of the brain.

This question seems now to be settled by the experiments of Dr. Legallois, a
physician of Paris, which prove, that in animals who have suffered decapi-
tation, the action of the heart does not cease as an immediate consequence
of the removal of the head ; but its cessation is an indirect effect, induced by
suspension of respiration. That respiration is immediately affected by
decapitation, and depends upon the influence of the brain transmitted
through the eighth pair of nerves. That the action of the heart will con-
tinue a long time after decapitation, if inflation of the lungs, or artificial
respiration, be performed; but, on the contrary, if the spinal marrow be de-
stroyed, the action of the heart ceases irrecoverably.

The inference from these experiments seems very conclusive, that the Spinal
marrow, and not the brain, is the source of the motions of the heart.

* See Cruikshank's Experiments on the Nerves and Spinal marrow of living Animals ;
London Philosophical Transactions for 1795. The eighth experiment has a particular relation
to this subject. Bichat's researches, part 2, article 9.

The Abbe Fontana has considered this subject in his Treatise on the Venom of the Viper,
vol. ii. page 194, English translation ; and also in some of his other works.

538 HUMBOLDT AND OTHERS ON LEGALLOls' PAPER.

It appears also by some of the experiments, that the power of motion in the
trunk of the body, is derived from the spinal marrow ; and that, when this
organ is partially destroyed, the parts which receive nerves from the destroy-
ed portion soon cease to live. By particular management of the spinal
marrow, one part of the body can be preserved alive for some time after the
other parts are dead.

These experiments of Dr. Legallois, commenced in 1806, or 1807, were com-
municated to the imperial Institute of France, in 1811. The committee of
that body, to whom they were referred, namely, Messrs. Humboldt, Halle,
and Percy, reported that the experiments had been repeated before them, at
three different meetings of several hours each ; and that, to allow themselves
sufficient time for reflection, they suffered an interval of a week to take place
between the meetings. The committee believe these experiments to have
proved,

1st. That the principle upon which all the movements of inspiration depend,
has its seat about that part of the medulla oblongata from which the nerves
of the eighth pair arise.

2nd. That the principle which animates each part of the trunk of the body,
is seated in that portion of the spinal marrow from which the nerves of
the part arise.

3d. That the source of the life and strength of the heart is also in the spinal
marrow ; not in any distinct portion, but in the whole of it.

4th. That the great sympathetic nerve is to be considered as originating in
the spinal marrow, and that the particular character of this nerve is to place
each of the parts to which it is distributed under the immediate influence of
the whole nervous power.

The interesting memoir of Dr. Legallois is confirmed to a certain degree by a
communication of B. C. Brodie to the Royal Society of London in 1810, in
which are detailed many very interesting experiments, which induced the
author to conclude,

That the influence of the brain is not directly necessary to the action of the
heart ; and

That when the brain is injured or removed, the action of the heart ceases
only because respiration is under its influence; and if, under these circum-
stances, respiration is artificially produced, the circulation will still continue.
These various experiments apply particularly to the cases in which the brain is
deficient, the effects of mental agitation on the heart are likewise reconcila-
ble to the theory which arises out of them. But they throw no light on the
question why the motions of the heart are so perfectly free from the influence
of the will : and although they seem to prove incostestably that the motion
of the heart is independent of the brain, it ought to be remembered that in
certain diseased states of the brain, where that organ appears to be com-
pressed, the action of the heart is often very irregular, and its contractions
less frequent than usual.

— For a later and more accurate account of the functions of respiration, the
reader is referred to Dunglison's " Human Physiology, 6th Ed., Phila.
1846.—

END OF VOL. I.